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Title: Steam Turbines

Author: Hubert E. Collins

Release date: January 2, 2009 [eBook #27687]
Most recently updated: January 4, 2021

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK STEAM
TURBINES ***

THE POWER PLANT LIBRARY

STEAM TURBINES

A B OOK O F I NS T RU CT I ON
F OR T HE ADJUS T ME N T AN D O P E R AT I ON OF
T HE P R I NC I PAL T YP E S OF T HI S
C L AS S OF P RI ME MOVE RS

c o mp i l e d an d wr i t t e n

by

HUBERT E. COLLINS

FIRST EDITION
S e c ond I mp r e s s i on

McGRAW-HILL BOOK COMPANY, Inc.
239 WEST 39TH STREET, NEW YORK
6 BOUVERIE STREET, LONDON, E. C.

Copyright, 1909, by the Hill Publishing Company

All rights reserved

TRANSCRIBER'S NOTES
The author of this book used the spellings "aline," "gage," and "hight" for
the conventional spellings "align," "gauge," and "height." As they are used
consistently and do not affect the sense, they have been left unchanged.
Some obvious typos and misspellings that do not affect the sense have been
silently corrected. The following substantive typographical errors have been
corrected: "being" to "bearing" (p. 68); "FIG. 50" to "FIG. 56" (p. 91), and
"Fig. 2" to "Fig. 73" (p. 159). Two other likely errors have been left as
queries: lead/load on p. 142 and beating/heating on p. 177. These five
changes are indentified by dotted red underlining with pop-up titles.

The numerous figures from the original are reproduced here as 16-level
grayscale images in .PNG format, scaled to no more than 512 pixels width
to fit a small window. When an image is enclosed in a broad gray border, it
is linked to a higher-resolution version; click to open it.

INTRODUCTION
This issue of the Power Handbook attempts to give a compact manual for
the engineer who feels the need of acquainting himself with steam turbines.
To accomplish this within the limits of space allowed, it has been necessary
to confine the work to the description of a few standard types, prepared
with the assistance of the builders. Following this the practical experience
of successful engineers, gathered from the columns of Power, is given. It is
hoped that the book will prove of value to all engineers handling turbines,
whether of the described types or not.
Hubert E. Collins.
New York, April, 1909.

CONTENTS
I. The Curtis Steam Turbine in Practice 1

II. Setting the Valves of the Curtis Turbine 31

III. Allis-Chalmers Steam Turbine 41

IV. Westinghouse-Parsons Turbine 58

V. Proper Method of Testing a Steam Turbine 112

VI. Testing a Steam Turbine 137

VII. Auxiliaries for Steam Turbines 154

VIII. Trouble with Steam Turbine Auxiliaries 172

I. THE CURTIS STEAM TURBINE IN
PRACTICE [1]
[1] Contributed to Power by Fred L. Johnson.

"Of the making of books there is no end." This seems especially true of
steam-turbine books, but the book which really appeals to the operating
engineer, the man who may have a turbine unloaded, set up, put in
operation, and the builders' representative out of reach before the man who
is to operate it fully realizes that he has a new type of prime mover on his
hands, with which he has little or no acquaintance, has not been written.
There has been much published, both descriptive and theoretical, about the
turbine, but so far as the writer knows, there is nothing in print that tells the
man on the job about the details of the turbine in plain language, and how to
handle these details when they need handling. The operating engineer does
not care why the moving buckets are made of a certain curvature, but he
does care about the distance between the moving bucket and the stationary
one, and he wants to know how to measure that distance, how to alter the
clearance, if necessary, to prevent rubbing. He doesn't care anything about
the area of the step-bearing, but he does want to know the way to get at the
bearing to take it down and put it up again, etc.

The lack of literature along this line is the writer's apology for what
follows. The Curtis 1500-kilowatt steam turbine will be taken first and
treated "from the ground up."
On entering a turbine plant on the ground floor, the attention is at once
attracted by a multiplicity of pumps, accumulators and piping. These are
called "auxiliaries" and will be passed for the present to be taken up later,
for though of standard types their use is comparatively new in power-plant
practice, and the engineer will find that more interruptions of service will
come from the auxiliaries than from the turbine itself.

B ui l de rs ' F o u n dat i o n P l an s I nc omp l e t e
It is impractical for the manufacturers to make complete foundation
drawings, as they are not familiar with the lay-out of pipes and the relative
position of other apparatus in the station. All that the manufacturers'
drawing is intended to do is to show the customer where it will be necessary
for him to locate his foundation bolts and opening for access to the step-
bearing.

FIG. 1

Fig. 1 shows the builders' foundation drawing, with the addition of
several horizontal and radial tubes introduced to give passage for the
various pipes which must go to the middle of the foundation. Entering
through the sides of the masonry they do not block the passage, which must
be as free as possible when any work is to be done on the step-bearing, or
lower guide-bearing. Entering the passage in the foundation, a large screw
is seen passing up through a circular block of cast iron with a 3/4-inch pipe
passing through it. This is the step-supporting screw. It supports the lower
half of the step-bearing, which in turn supports the entire revolving part of
the machine. It is used to hold the wheels at a proper hight in the casing,
and adjust the clearance between the moving and stationary buckets. The
large block which with its threaded bronze bushing forms the nut for the
screw is called the cover-plate, and is held to the base of the machine by
eight 1-1/2-inch cap-screws. On the upper side are two dowel-pins which
enter the lower step and keep it from turning. (See Figs. 2 and 3.)

FIG. 2

FIG. 3

The step-blocks are very common-looking chunks of cast iron, as will be
seen by reference to Fig. 4. The block with straight sides (the lower one in
the illustration) has the two dowel holes to match the pins spoken of, with a
hole through the center threaded for 3/4-inch pipe. The step-lubricant is
forced up through this hole and out between the raised edges in a film,
floating the rotating parts of the machine on a frictionless disk of oil or
water. The upper step-block has two dowel-pins, also a key which fits into a
slot across the bottom end of the shaft.

FIG. 4
The upper side of the top block is counterbored to fit the end of the shaft.
The counterbore centers the block. The dowel-pins steer the key into the
key-way across the end of the shaft, and the key compels the block to turn
with the shaft. There is also a threaded hole in the under side of the top
block. This is for the introduction of a screw which is used to pull the top
block off the end of the shaft. If taken off at all it must be pulled, for the

dowel-pins, key and counterbore are close fits. Two long bolts with threads
the whole length are used if it becomes necessary to take down the step or
other parts of the bottom of the machine. Two of the bolts holding the
cover-plate in place are removed, these long bolts put in their places and the
nuts screwed up against the plate to hold it while the remaining bolts are
removed.

H ow to L o we r S t e p -B e a ri ng s to E xa mi ne
T he m
Now, suppose it is intended to take down the step-bearings for examination.
The first thing to do is to provide some way of holding the shaft up in its
place while we take its regular support from under it. In some machines,
inside the base, there is what is called a "jacking ring." It is simply a loose
collar on the shaft, which covers the holes into which four plugs are
screwed. These are taken out and in their places are put four hexagonal-
headed screws provided for the purpose, which are screwed up. This brings
the ring against a shoulder on the shaft and then the cover-plate and step
may be taken down.
While all the machines have the same general appearance, there are
some differences in detail which may be interesting. One difference is due
to the sub-base which is used with the oil-lubricated step-bearings. This
style of machine has the jacking ring spoken of, while others have neither
sub-base nor jacking ring, and when necessary to take down the step a
different arrangement is used.

FIG. 5

A piece of iron that looks like a big horseshoe (Fig. 5) is used to hold the
shaft up. The flange that covers the entrance to the exhaust base is taken off
and a man goes in with the horseshoe-shaped shim and an electric light.
Other men take a long-handled wrench and turn up the step-screw until the
man inside the base can push the horseshoe shim between the shoulder on
the shaft and the guide-bearing casing. The men on the wrench then back
off and the horseshoe shim supports the weight of the machine. When the
shim is in place, or the jacking ring set up, whichever the case may be, the
cover-plate bolts may be taken out, the nuts on the long screws holding the
cover in place.
The 3/4-inch pipe which passes up through the step-screw is taken down
and, by means of the nuts on the long screws, the cover-plate is lowered
about 2 inches. Then through the hole in the step-screw a 3/4-inch rod with
threads on both ends is passed and screwed into the top step; then the cover-
plate is blocked so it cannot rise and, with a nut on the lower end of the 3/4-
inch rod, the top step is pulled down as far as it will come. The cover-plate
is let down by means of the two nuts, and the top step-block follows. When
it is lowered to a convenient hight it can be examined, and the lower end of
the shaft and guide-bearing will be exposed to view.

FIG. 6
The lower guide-bearing (Fig. 6) is simply a sleeve flanged at one end,
babbitted on the inside, and slightly tapered on the outside where it fits into
the base. The flange is held securely in the base by eight 3/4-inch cap-

screws. Between the cap-screw holes are eight holes tapped to 3/4-inch, and
when it is desired to take the bearing down the cap-screws are taken out of
the base and screwed into the threaded holes and used as jacks to force the
guide-bearing downward. Some provision should be made to prevent the
bearing from coming down "on the run," for being a taper fit it has only to
be moved about one-half inch to be free. Two bolts, about 8 inches long,
screwed into the holes that the cap-screws are taken from, answer nicely, as
a drop that distance will not do any harm, and the bearing can be lowered
by hand, although it weighs about 200 pounds.
The lower end of the shaft is covered by a removable bushing which is
easily inspected after the guide-bearing has been taken down. If it is
necessary to take off this bushing it is easily done by screwing four 5/8-inch
bolts, each about 2 feet long, into the tapped holes in the lower end of the
bushing, and then pulling it off with a jack. (See Fig. 7.)
Each pipe that enters the passage in the foundation should be connected
by two unions, one as close to the machine as possible and the other close
to the foundation. This allows the taking down of all piping in the passage
completely and quickly without disturbing either threads or lengths.

FIG. 7

S t u d y i ng t h e B l ue p r i n t s
Fig. 8 shows an elevation and part-sectional view of a 1500-kilowatt Curtis
steam turbine. If one should go into the exhaust base of one of these
turbines, all that could be seen would be the under side of the lower or
fourth-stage wheel, with a few threaded holes for the balancing plugs which
are sometimes used. The internal arrangement is clearly indicated by the
illustration, Fig. 8. It will be noticed that each of the four wheels has an
upper and a lower row of buckets and that there is a set of stationary
buckets for each wheel between the two rows of moving buckets. These
stationary buckets are called intermediates, and are counterparts of the
moving buckets. Their sole office is to redirect the steam which has passed
through the upper buckets into the lower ones at the proper angle.

FIG. 8. ELEVATION AND PART-SECTIONAL VIEW OF A 1500-

KILOWATT CURTIS TURBINE
The wheels are kept the proper distance apart by the length of hub, and
all are held together by the large nut on the shaft above the upper wheel.
Each wheel is in a separate chamber formed by the diaphragms which rest
on ledges on the inside of the wheel-case, their weight and steam pressure
on the upper side holding them firmly in place and making a steam-tight
joint where they rest. At the center, where the hubs pass through them, there
is provided a self-centering packing ring (Fig. 9), which is free to move
sidewise, but is prevented from turning, by suitable lugs. This packing is a
close running fit on the hubs of the wheel and is provided with grooves
(plainly shown in Fig. 9) which break up and diminish the leakage of steam
around each hub from one stage to the next lower. Each diaphragm, with the
exception of the top one, carries the expanding nozzles for the wheel
immediately below.

FIG. 9

The expanding nozzles and moving buckets constantly increase in size
and number from the top toward the bottom. This is because the steam
volume increases progressively from the admission to the exhaust and the
entire expansion is carried out in the separate sets of nozzles, very much as
if it were one continuous nozzle; but with this difference, not all of the
energy is taken out of the steam in any one set of nozzles. The idea is to
keep the velocity of the steam in each stage as nearly constant as possible.

The nozzles in the diaphragms and the intermediates do not, except in the
lowest stage, take up the entire circumference, but are proportioned to the
progressive expansion of steam as it descends toward the condenser.

C l e a ra nc e
While the machine is running it is imperative that there be no rubbing
contact between the revolving and stationary parts, and this is provided for
by the clearance between the rows of moving buckets and the intermediates.
Into each stage of the machine a 2-inch pipe hole is drilled and tapped.
Sometimes this opening is made directly opposite a row of moving buckets
as in Fig. 10, and sometimes it is made opposite the intermediate. When
opposite a row of buckets, it will allow one to see the amount of clearance
between the buckets and the intermediates, and between the buckets and the
nozzles. When drilled opposite the intermediates, the clearance is shown top
and bottom between the buckets and intermediates. (See Fig. 11.) This
clearance is not the same in all stages, but is greatest in the fourth stage and
least in the first. The clearances in each stage are nearly as follows: First
stage, 0.060 to 0.080; second stage, 0.080 to 0.100; third stage, 0.080 to
0.100; fourth stage, 0.080 to 0.200. These clearances are measured by what
are called clearance gages, which are simply taper slips of steel about 1/2-
inch wide accurately ground and graduated, like a jeweler's ring gage, by
marks about 1/2-inch apart; the difference in thickness of the gage is one-
thousandth of an inch from one mark to the next.

FIG. 10

FIG. 11
To determine whether the clearance is right, one of the 2-inch plugs is
taken out and some marking material, such as red lead or anything that
would be used on a surface plate or bearing to mark the high spots is rubbed

on the taper gage, and it is pushed into the gap between the buckets and
intermediates as far as it will go, and then pulled out, the marking on the
gage showing just how far in it went, and the nearest mark giving in
thousandths of an inch the clearance. This is noted, the marking spread
again, and the gage tried on the other side, the difference on the gage
showing whether the wheel is high or low. Whichever may be the case the
hight is corrected by the step-bearing screw. The wheels should be placed as
nearly in the middle of the clearance space as possible. By some operators
the clearance is adjusted while running, in the following manner: With the
machine running at full speed the step-bearing screw is turned until the
wheels are felt or heard to rub lightly. The screw is marked and then turned
in the opposite direction until the wheel rubs again. Another mark is made
on the screw and it is then turned back midway between the two marks.
Either method is safe if practiced by a skilful engineer. In measuring the
clearance by the first method, the gage should be used with care, as it is
possible by using too much pressure to swing the buckets and get readings
which could be misleading. To an inexperienced man the taper gages would
seem preferable. In the hands of a man who knows what he is doing and
how to do it, a tapered pine stick will give as satisfactory results as the most
elaborate set of hardened and ground clearance gages.

Referring back to Fig. 11, at A is shown one of the peep-holes opposite
the intermediate in the third stage wheel for the inspection of clearance. The
taper clearance gage is inserted through this hole both above and below the
intermediate, and the distance which it enters registers the clearance on that
side. This sketch also shows plainly how the shrouding on the buckets and
the intermediates extends beyond the sharp edges of the buckets, protecting
them from damage in case of slight rubbing. In a very few cases wheels
have been known to warp to such an extent from causes that were not
discovered until too late, that adjustment would not stop the rubbing. In
such cases the shrouding has been turned or faced off by a cutting-off tool
used through the peep-hole.

C a rb on P ac ki ng U se d
Where the shaft passes through the upper head of the wheel-case some
provision must be made to prevent steam from the first stage escaping. This
is provided for by carbon packing (Fig. 12), which consists of blocks of
carbon in sets in a packing case bolted to the top head of the wheel-case.
There are three sets of these blocks, and each set is made of two rings of
three segments each. One ring of segments breaks joints with its mate in the
case, and each set is separated from the others by a flange in the case in
which it is held. In some cases the packing is kept from turning by means of
a link, one end of which is fastened to the case and the other to the packing
holder. Sometimes light springs are used to hold the packing against the
shaft and in some the pressure of steam in the case does this. There is a
pipe, also shown in Fig. 12, leading from the main line to the packing case,
the pressure in the pipe being reduced. The space between the two upper
sets of rings is drained to the third stage by means of a three-way cock,
which keeps the balance between the atmosphere and packing-case
pressure. The carbon rings are fitted to the shaft with a slight clearance to
start with, and very soon get a smooth finish, which is not only practically
steam-tight but frictionless.

FIG. 12

The carbon ring shown in Fig. 12 is the older design. The segments are
held against the flat bearing surface of the case by spiral springs set in brass
ferrules. The circle is held together by a bronze strap screwed and drawn
together at the ends by springs. Still other springs press the straps against
the surface upon which the carbon bears, cutting off leaks through joints
and across horizontal surfaces of the carbon. The whole ring is prevented
from turning by a connecting-rod which engages a pin in the hole, like
those provided for the springs.

FIG. 13

FIG. 14

FIG. 15

FIG. 16

T h e S af e t y - s top
There are several designs of safety-stop or speed-limit devices used with
these turbines, the simplest being of the ring type shown in Fig. 13. This
consists of a flat ring placed around the shaft between the turbine and
generator. The ring-type emergencies are now all adjusted so that they
normally run concentric with the shaft, but weighted so that the center of
gravity is slightly displaced from the center. The centrifugal strain due to
this is balanced by helical springs. But when the speed increases the
centrifugal force moves the ring into an eccentric position, when it strikes a
trigger and releases a weight which, falling, closes the throttle and shuts off
the steam supply. The basic principle upon which all these stops are
designed is the same—the centrifugal force of a weight balanced by a
spring at normal speed. Figs. 14, 15, and 16 show three other types.

T h e M e c hani c al V alve -G e ar
Fig. 17 shows plainly the operation of the mechanical valve-gear. The
valves are located in the steam chests, which are bolted to the top of the
casing directly over the first sets of expansion nozzles. The chests, two in
number, are on opposite sides of the machine. The valve-stems extend
upward through ordinary stuffing-boxes, and are attached to the notched
cross-heads by means of a threaded end which is prevented from screwing
in or out by a compression nut on the lower end of the cross-head. Each
cross-head is actuated by a pair of reciprocating pawls, or dogs (shown
more plainly in the enlarged view, Fig. 18), one of which opens the valve
and the other closes it. The several pairs of pawls are hung on a common
shaft which receives a rocking motion from a crank driven from a worm
and worm-wheel by the turbine shaft. The cross-heads have notches milled
in the side in which the pawls engage to open or close the valve, this
engagement being determined by what are called shield-plates, A (Fig. 18),
which are controlled by the governor. These plates are set, one a little ahead
of the other, to obtain successive opening or closing of the valves. When

more steam is required the shield plate allows the proper pawl to fall into its
notch in the cross-head and lift the valve from its seat. If less steam is
wanted the shield-plate rises and allows the lower pawl to close the valve
on the down stroke.

FIG. 17

FIG. 18

The valves, as can easily be seen, are very simple affairs, the steam
pressure in the steam chest holding the valve either open or shut until it is
moved by the pawl on the rock-shaft. The amount of travel on the rock-
shaft is fixed by the design, but the proportionate travel above and below
the horizontal is controlled by the length of the connecting-rods from the
crank to the rock-shaft. There are besides the mechanical valve-gear the
electric and hydraulic, but these will be left for a future article.

T he G ove rn or
The speed of the machine is controlled by the automatic opening and
closing of the admission valves under the control of a governor (Fig. 19), of
the spring-weighted type attached directly to the top end of the turbine
shaft. The action of the governor depends on the balance of force exerted by
the spring, and the centrifugal effort of the rectangular-shaped weights at
the lower end; the moving weights acting through the knife-edge
suspension tend to pull down the lever against the resistance of the heavy
helical spring. The governor is provided with an auxiliary spring on the
outside of the governor dome for varying the speed while synchronizing.
The tension of the auxiliary spring is regulated by a small motor wired to
the switchboard. This spring should be used only to correct slight changes
in speed. Any marked change should be corrected by the use of the large
hexagonal nut in the upper plate of the governor frame. This nut is screwed
down to increase the speed, and upward to decrease it.

FIG. 19

T h e S tag e V alve s
Fig. 20 represents one of the several designs of stage valve, sometimes
called the overload valve, the office of which is to prevent too high pressure
in the first stage in case of a sudden overload, and to transfer a part of the
steam to a special set of expanding nozzles over the second-stage wheel.
This valve is balanced by a spring of adjustable tension, and is, or can be,
set to open and close within a very small predetermined range of first-stage

pressure. The valve is intended to open and close instantly, and to supply or
cut off steam from the second stage, without affecting the speed regulation
or economy of operation. If any leaking occurs past the valve it is taken
care of by a drip-pipe to the third stage.

FIG. 20

The steam which passes through the automatic stage valves and is
admitted to the extra set of nozzles above the second-stage wheel acts upon
this wheel just the same as the steam which passes through the regular
second-stage nozzles; i.e., all the steam which goes through the machine
tends to hasten its speed, or, more accurately, does work and maintains the
speed of the machine.

II. SETTING THE VALVES OF THE CURTIS
TURBINE [2]
[2] Contributed to Power by F. L. Johnson.

Under some conditions of service the stage valve in the Curtis turbine
will not do what it is designed to do. It is usually attached to the machine in
such manner that it will operate with, or a little behind, in the matter of
time, the sixth valve. The machine is intended to carry full load with only
the first bank of five valves in operation, with proper steam pressure and
vacuum. If the steam pressure is under 150 pounds, or the vacuum is less
than 28 inches, the sixth valve may operate at or near full load, and also
open the stage valve and allow steam to pass to the second-stage nozzles at
a much higher rate of speed than the steam which has already done some
work in the first-stage wheel. The tendency is to accelerate unduly the
speed of the machine. This is corrected by the governor, but the correction
is usually carried too far and the machine slows down. With the stage valve
in operation, at a critical point the regulation is uncertain and irregular, and
its use has to be abandoned. The excess first-stage pressure will then be
taken care of by the relief valve, which is an ordinary spring safety valve
(not pop) which allows the steam to blow into the atmosphere.
The mechanical valve-gear does not often get out of order, but
sometimes the unexpected happens. The shop man may not have properly
set up the nuts on the valve-stems; or may have fitted the distance bushings
between the shield plates too closely; the superheat of the steam may distort
the steam chest slightly and produce friction that will interfere with the
regulation. If any of the valve-stems should become loose in the cross-
heads they may screw themselves either in or out. If screwed out too far, the
valve-stem becomes too long and the pawl in descending will, after the
valve is seated, continue downward until it has broken something. If

screwed in, the cross-head will be too low for the upper pawl to engage and
the valve will not be opened. This second condition is not dangerous, but
should be corrected. The valve-stems should be made the right length, and
all check-nuts set up firmly. If for any purpose it becomes necessary to "set
the valves" on a 1500-kilowatt mechanical gear, the operator should
proceed in the following manner.

S e t t i ng t h e V alv e s of a 1500-K i l owat t
C urt i s T ur b i n e
We will consider what is known as the "mechanical" valve-gear, with two
sets of valves, one set of five valves being located on each side of the
machine.

FIG. 21

In setting the valves we should first "throw out" all pawls to avoid
breakage in case the rods are not already of proper length, holding the
pawls out by slipping the ends of the pawl springs over the points of the
pawls, as seen in Fig. 21. Then turn the machine slowly by hand until the
pawls on one set of valves are at their highest point of travel, then with the
valves wide open adjust the drive-rods, i.e., the rods extending from the
crank to the rock-shaft, so that there is 1/32 of an inch clearance (shown
dotted in Fig. 17, Chap. I) at the point of opening of the pawls when they
are "in." (See Fig. 22.) Then set up the check-nuts on the drive-rod. Turn the
machine slowly, until the pawls are at their lowest point of travel. Then,
with the valves closed, adjust each valve-stem to give 1/32 of an inch
clearance at the point of closing of the pawls when they are "in," securely
locking the check-nut as each valve is set. Repeat this operation on the
other side of the machine and we are ready to adjust the governor-rods.
(Valves cannot be set on both sides of the machine at the same time, as the
pawls will not be in the same relative position, due to the angularity of the
drive-rods.)

FIG. 22

Next, with the turbine running, and the synchronizing spring in mid-
position, adjust the governor-rods so that the turbine will run at the normal
speed of 900 revolutions per minute when working on the fifth valve, and
carrying full load. The governor-rods for the other side of the turbine
(controlling valves Nos. 6 to 10) should be so adjusted that the speed
change between the fifth and sixth valves will not be more than three or
four revolutions per minute.

The valves of these turbines are all set during the shop test and the rods
trammed with an 8-inch tram. Governors are adjusted for a speed range of 2
per cent. between no load and full load (1500 kilowatt), or 4 per cent.
between the mean speeds of the first and tenth valves (no load to full
overload capacity).

The rods which connect the governor with the valve-gear have ordinary
brass ends or heads and are adjusted by right-and-left threads and secured
by lock-nuts. They are free fits on the pins which pass through the heads,
and no friction is likely to occur which will interfere with the regulation,
but too close work on the shield-plate bushings, or a slight warping of the
steam chest, will often produce friction which will seriously impair the
regulation. If it is noticed that the shield-plate shaft has any tendency to
oscillate in unison with the rock-shaft which carries the pawls, it is a sure
indication that the shield-plates are not as free as they should be, and should
be attended to. The governor-rod should be disconnected, the pawls thrown
out and the pawl strings hooked over the ends.

The plates should then be rocked up and down by hand and the friction
at different points noted. The horizontal rod at the back of the valve-gear
may be loosened and the amount of end play of each individual shield-plate
noticed and compared with the bushings on the horizontal rod at the back
which binds the shield-plates together. If the plates separately are found to
be perfectly free they may be each one pushed hard over to the right or left
and wedged; then each bushing tried in the space between the tail-pieces of
the plates. It will probably be found that the bushings are not of the right
length, due to the alteration of the form of the steam chest by heat. It will
generally be found also that the bushings are too short, and that the length
can be corrected by very thin washers of sheet metal. It has been found in
some instances that the thin bands coming with sectional pipe covering
were of the right thickness.
After the length of the bushings is corrected the shield-plates may be
assembled, made fast and tested by rocking them up and down, searching
for signs of sticking. If none occurs, the work has been correctly done, and

there will be no trouble from poor regulation due to friction of the shield-
plates.

T he B af f l e r
The water which goes to the step-bearing passes through a baffler, the latest
type of which is shown by Fig. 23. It is a device for restricting the flow of
water or oil to the step- and guide-bearing. The amount of water necessary
to float the machine and lubricate the guide-bearing having been
determined by calculation and experiment, the plug is set at that point
which will give the desired flow. The plug is a square-threaded worm, the
length of which and the distance which it enters the barrel of the baffler
determining the amount of flow. The greater the number of turns which the
water must pass through in the worm the less will flow against the step-
pressure.

FIG. 23
The engineers who have settled upon the flow and the pressure decided
that a flow of from 4-1/2 to 5-1/2 gallons per minute and a step-pressure of
from 425 to 450 pounds is correct. These factors are so dependent upon
each other and upon the conditions of the step-bearing itself that they are
sometimes difficult to realize in every-day work; nor is it necessary. If the
machine turns freely with a lower pressure than that prescribed by the

engineers, there is no reason for raising this pressure; and there is only one
way of doing it without reducing the area of the step-bearing, and that is by
obstructing the flow of water in the step-bearing itself.
A very common method used is that of grinding. The machine is run at
about one-third speed and the step-water shut off for 15 or 20 seconds. This
causes grooves and ridges on the faces of the step-bearing blocks, due to
their grinding on each other, which obstruct the flow of water between the
faces and thus raises the pressure. It seems a brutal way of getting a
scientific result, if the result desired can be called scientific. The grooving
and cutting of the step-blocks will not do any harm, and in fact they will aid
in keeping the revolving parts of the machine turning about its mechanical
center.

The operating engineer will be very slow to see the utility of the baffler,
and when he learns, as he will sometime, that the turbine will operate
equally well with a plug out as with it in the baffler, he will be inclined to
remove the baffler. It is true that with one machine operating on its own
pump it is possible to run without the baffler, and it is also possible that in
some particular case two machines having identical step-bearing pressures
might be so operated. The baffler, however, serves a very important
function, as described more fully as follows: It tends to steady the flow
from the pump, to maintain a constant oil film as the pressure varies with
the load, and when several machines are operating on the same step-bearing
system it is the only means which fixes the flow to the different machines
and prevents one machine from robbing the others. Therefore, even if an
engineer felt inclined to remove the baffler he would be most liable to
regret taking such a step.

If the water supply should fail from any cause and the step-bearing
blocks rub together, no great amount of damage will result. The machine
will stop if operated long under these conditions, for if steam pressure is
maintained the machine will continue in operation until the buckets come
into contact, and if the step-blocks are not welded together the machine may
be started as soon as the water is obtained. If vibration occurs it will

probably be due to the rough treatment of the step-blocks, and may be cured
by homeopathic repeat-doses of grinding, say about 15 seconds each. If the
step-blocks are welded a new pair should be substituted and the damaged
ones refaced.

Some few experimental steps of spherical form, called "saucer" steps,
have been installed with success (see Fig. 24). They seem to aid the lower
guide-bearing in keeping the machine rotating about the mechanical center
and reduce the wear on the guide-bearing. In some instances, too, cast-iron
bushings have been substituted for bronze, with marked success. There
seems to be much less wear between cast-iron and babbitt metal than
between bronze and babbitt metal. The matter is really worth a thorough
investigation.

FIG. 24

III. ALLIS-CHALMERS COMPANY STEAM
TURBINE
In Fig. 25 may be seen the interior construction of the steam turbine built by
Allis-Chalmers Co., of Milwaukee, Wis., which is, in general, the same as
the well-known Parsons type. This is a plan view showing the rotor resting
in position in the lower half of its casing.

FIG. 25
Fig. 26 is a longitudinal cross-section cut of rotor and both lower and
upper casing. Referring to Fig. 26 the steam comes in from the steam-pipe
at C and passes through the main throttle or regulating valve D, which is a
balanced valve operated by the governor. Steam enters the cylinder through
the passage E.
Turning in the direction of the bearing A, it passes through alternate
stationary and revolving rows of blades, finally emerging at F and going out
by way of G to the condenser or to atmosphere. H, J, and K represent three
stages of blading. L, M, and Z are the balance pistons which counterbalance
the thrust on the stages H, J, and K. O and Q are equalizing pipes, and for
the low-pressure balance piston similar provision is made by means of
passages (not shown) through the body of the spindle.

FIG. 26
R indicates a small adjustable collar placed inside the housing of the
main bearing B to hold the spindle in a position where there will be such a
clearance between the rings of the balance pistons and those of the cylinder
as to reduce the leakage of steam to a minimum and at the same time
prevent actual contact under varying temperature.
At S and T are glands which provide a water seal against the inleakage of
air and the outleakage of steam. U represents the flexible coupling to the
generator. V is the overload or by-pass valve used for admitting steam to
intermediate stage of the turbine. W is the supplementary cylinder to
contain the low-pressure balance piston. X and Y are reference letters used
in text of this chapter to refer to equalizing of steam pressure on the low-
pressure stage of the turbine. The first point to study in this construction is
the arrangement of "dummies" L, M, and Z. These dummy rings serve as
baffles to prevent steam leakage past the pistons, and their contact at high
velocity means not only their own destruction, but also damage to or the
wrecking of surrounding parts. A simple but effective method of eliminating
this difficulty is found in the arrangement illustrated in this figure. The two
smaller balance pistons, L and M, are allowed to remain on the high-
pressure end; but the largest piston, Z, is placed upon the low-pressure end
of the rotor immediately behind the last ring of blades, and working inside
of the supplementary cylinder W. Being backed up by the body of the
spindle, there is ample stiffness to prevent warping. This balance piston,

which may also be plainly seen in Fig. 25, receives its steam pressure from
the same point as the piston M, but the steam pressure, equalized with that
on the third stage of the blading, X, is through holes in the webs of the
blade-carrying rings. Entrance to these holes is through the small annular
opening in the rotor, visible in Fig. 25 between the second and third barrels.
As, in consequence of varying temperatures, there is an appreciable
difference in the endwise expansion of the spindle and cylinder, the baffling
rings in the low-pressure balance piston are so made as to allow for this
difference. The high-pressure end of the spindle being held by the collar
bearing, the difference in expansion manifests itself at the low-pressure end.
The labyrinth packing of the high-pressure and intermediate pistons has a
small axial and large radial clearance, whereas the labyrinth packing of the
piston Z has, vice versa, a small radial and large axial clearance.
Elimination of causes of trouble with the low-pressure balance piston not
only makes it possible to reduce the diameter of the cylinder, and prevent
distortion, but enables the entire spindle to be run with sufficiently small
clearance to obviate any excessive leakage of steam.

D e ta i l o f B l ade C o ns t r uc t i o n
In this construction the blades are cut from drawn stock, so that at its root it
is of angular dovetail shape, while at its tip there is a projection. To hold the
roots of the blades firmly, a foundation ring is provided, as shown at A in
Fig. 27. This foundation ring is first formed to a circle of the proper
diameter, and then slots are cut in it. These slots are accurately spaced and
inclined to give the right pitch and angle to the blades (Fig. 28), and are of
dovetail shape to receive the roots of the blades. The tips of the blades are
substantially bound together and protected by means of a channel-shaped
shroud ring, illustrated in Fig. 31 and at B in Fig. 27. Fig. 31 shows the
cylinder blading separate, and Fig. 27 shows both with the shrouding. In
these, holes are punched to receive the projections on the tips of the blades,
which are rivetted over pneumatically.

FIG. 27
The foundation rings themselves are of dovetail shape in cross-section,
and, after receiving the roots of the blades, are inserted in dovetailed

grooves in the cylinder and rotor, where they are firmly held in place by
keypieces, as may be seen at C in Fig. 27. Each keypiece, when driven in
place, is upset into an undercut groove, indicated by D in Fig. 27, thereby
positively locking the whole structure together. Each separate blade is
firmly secured by the dovetail shape of the root, which is held between the
corresponding dovetailed slot in the foundation ring and the undercut side
of the groove.

FIG. 28
Fig. 29, from a photograph of blading fitted in a turbine, illustrates the
construction, besides showing the uniform spacing and angles of the blades.

FIG. 29

The obviously thin flanges of the shroud rings are purposely made in
that way, so that, in case of accidental contact between revolving and
stationary parts, they will wear away enough to prevent the blades from
being ripped out. This protection, however, is such that to rip them out a
whole half ring of blades must be sheared off at the roots. The strength of
the blading, therefore, depends not upon the strength of an individual blade,
but upon the combined shearing strength of an entire ring of blades.

FIG. 30

The blading is made up and inserted in half rings, and Fig. 30 shows two
rings of different sizes ready to be put in place. Fig. 31 shows a number of
rows of blading inserted in the cylinder of an Allis-Chalmers steam turbine,
and Fig. 32 gives view of blading in the same turbine after nearly three
years' running.

FIG. 31

FIG. 32

T he G ove rn or
Next in importance to the difference in blading and balance piston
construction, is the governing mechanism used with these machines. This
follows the well-known Hartung type, which has been brought into
prominence, heretofore largely in connection with hydraulic turbines; and
the governor, driven directly from the turbine shaft by means of cut gears
working in an oil bath, is required to operate the small, balanced oil relay-
valve only, while the two steam valves, main and by-pass (or overload), are
controlled by an oil pressure of about 20 pounds per square inch, acting

upon a piston of suitable size. In view of the fact that a turbine by-pass
valve opens only when the unit is required to develop overload, or the
vacuum fails, a good feature of this governing mechanism is that the valve
referred to can be kept constantly in motion, thereby preventing sticking in
an emergency, even though it be actually called into action only at long
intervals. Another feature of importance is that the oil supply to the
bearings, as well as that to the governor, can be interconnected so that the
governor will automatically shut off the steam if the oil supply fails and
endangers the bearings. This mechanism is also so proportioned that, while
responding quickly to variations in load, its sensitiveness is kept within
such bounds as to secure the best results in the parallel operation of
alternators. The governor can be adjusted for speed while the turbine is in
operation, thereby facilitating the synchronizing of alternators and dividing
the load as may be desired.

In order to provide for any possible accidental derangement of the main
governing mechanism, an entirely separate safety or over-speed governor is
furnished. This governor is driven directly by the turbine shaft without the
intervention of gearing, and is so arranged and adjusted that, if the turbine
should reach a predetermined speed above that for which the main governor
is set, the safety governor will come into action and trip a valve which
entirely shuts off the steam supply, bringing the turbine to a stop.

L ubr i cat i o n
Lubrication of the four bearings, which are of the self-adjusting, ball and
socket pattern, is effected by supplying an abundance of oil to the middle of
each bearing and allowing it to flow out at the ends. The oil is passed
through a tubular cooler, having water circulation, and pumped back to the
bearings. Fig. 33 shows the entire arrangement graphically and much more
clearly than can be explained in words. The oil is circulated by a pump
directly operated from the turbine, except where the power-house is
provided with a central oiling system. Particular stress is laid by the

builders upon the fact that it is not necessary to supply the bearings with oil
under pressure, but only at a head sufficient to enable it to run to and
through the bearings; this head never exceeding a few feet. With each
turbine is installed a separate direct-acting steam pump for circulating oil
for starting up. This will be referred to again under the head of operating.

FIG. 33

G e n e rator
The turbo-generator, which constitutes the electrical end of this unit, is
totally enclosed to provide for noiseless operation, and forced ventilation is
secured by means of a small fan carried by the shaft on each end of the
rotor. The air is taken in at the ends of the generator, passes through the fans
and is discharged over the end connections of the armature coils into the
bottom of the machine, whence it passes through the ventilating ducts of the
core to an opening at the top. The field core is, according to size, built up
either of steel disks, each in one piece, or of steel forgings, so as to give
high magnetic permeability and great strength. The coils are placed in radial
slots, thereby avoiding side pressure on the slot insulation and the complex

stresses resulting from centrifugal force, which, in these rotors, acts normal
to the flat surface of the strip windings.

O p e rat i o n
As practically no adjustments are necessary when these units are in
operation, the greater part of the attention required by them is involved in
starting up and shutting down, which may be described in detail as follows:
To Start Up

First, the auxiliary oil pump is set going, and this is speeded up until the
oil pressure shows a hight sufficient to lift the inlet valve and oil is flowing
steadily at the vents on all bearings. The oil pressure then shows about 20 to
25 pounds on the "Relay Oil" gage, and 2 to 4 pounds on the "Bearing Oil"
gage. Next the throttle is opened, without admitting sufficient steam to the
turbine to cause the spindle to turn, and it is seen that the steam exhausts
freely into the atmosphere, also that the high-pressure end of the turbine
expands freely in its guides. Water having been allowed to blow out through
the steam-chest drains, the drains are closed and steam is permitted to
continue flowing through the turbine not less than a half an hour (unless the
turbine is warm to start with, when this period may be reduced) still without
turning the spindle. After this it is advisable to shut off steam and let the
turbine stand ten minutes, so as to warm thoroughly, during which time the
governor parts may be oiled and any air which may have accumulated in the
oil cylinder above the inlet valve blown off. Then the throttle should be
opened sufficiently to start the turbine spindle to revolving very slowly and
the machine allowed to run in this way for five minutes.
Successive operations may be mentioned briefly as admitting water to
the oil cooler; bringing the turbine up to speed, at the same time slowing
down the auxiliary oil pump and watching that the oil pressures are kept up
by the rotary oil pump on the turbine; turning the water on to the glands
very gradually and, before putting on vacuum, making sure that there is just

enough water to seal these glands properly; and starting the vacuum
gradually just before putting on the load. These conditions having been
complied with, the operator next turns his attention to the generator, putting
on the field current, synchronizing carefully and building up the load on the
unit gradually.
The principal precautions to be observed are not to start without
warming up properly, to make sure that oil is flowing freely through the
bearings, that vacuum is not put on until the water glands seal, and to avoid
running on vacuum without load on the turbine.

I n O p e r at i o n
In operation all that is necessary is to watch the steam pressure at the
"Throttle" and "Inlet" gages, to see that neither this pressure nor the steam
temperature varies much; to keep the vacuum constant, as well as pressures
on the water glands and those indicated by the "Relay Oil" and "Bearing
Oil" gages; to take care that the temperatures of the oil flowing to and from
the bearings does not exceed 135 degrees Fahr. (at which temperature the
hand can comfortably grasp the copper oil-return pipes); to see that oil
flows freely at all vents on the bearings, and that the governor parts are
periodically oiled. So far as the generator is concerned, it is only essential to
follow the practice common in all electric power plant operation, which
need not be reviewed here.
Stopping the turbine is practically the reverse of starting, the successive
steps being as follows: starting the auxiliary oil pump, freeing it of water
and allowing it to run slowly; removing the load gradually; breaking the
vacuum when the load is almost zero, shutting off the condenser injection
and taking care that the steam exhausts freely into the atmosphere; shutting
off the gland water when the load and vacuum are off; pulling the automatic
stop to trip the valve and shut off steam and, as the speed of the turbine
decreases, speeding up the auxiliary oil pump to maintain pressure on the
bearings; then, when the turbine has stopped, shutting down the auxiliary

oil pump, turning off the cooling water, opening the steam chest drains and
slightly oiling the oil inlet valve-stem. During these operations the chief
particulars to be heeded are: not to shut off the steam before starting the
auxiliary oil pump nor before the vacuum is broken, and not to shut off the
gland water with vacuum on the turbine. The automatic stop should also
remain unhooked until the turbine is about to be started up again.

G e ne r al
Water used in the glands of the turbine must be free from scale-forming
impurities and should be delivered at the turbine under a steady pressure of
not less than 15 pounds. The pressure in the glands will vary from 4 to 10
pounds. This water may be warm. In the use of water for the cooling coils
and of oil for the lubricating system, nothing more is required than ordinary
good sense dictates. An absolutely pure mineral oil must be supplied, of a
non-foaming character, and it should be kept free through filtering from any
impurities.
The above refers particularly to Allis-Chalmers turbines of the type
ordinarily used for power service. For turbines built to be run non-
condensing, the part relating to vacuum does not, of course, apply.

IV. WESTINGHOUSE-PARSONS STEAM
TURBINE
While the steam turbine is simple in design and construction and does not
require constant tinkering and adjustment of valve gears or taking up of
wear in the running parts, it is like any other piece of fine machinery in that
it should receive intelligent and careful attention from the operator by
inspection of the working parts that are not at all times in plain view. Any
piece of machinery, no matter how simple and durable, if neglected or
abused will in time come to grief, and the higher the class of the machine
the more is this true.
Any engineer who is capable of running and intelligently taking care of a
reciprocating engine can run and take care of a turbine, but if he is to be
anything more than a starter and stopper, it is necessary that he should know
what is inside of the casing, what must be done and avoided to prevent
derangement, and to keep the machine in continued and efficient operation.
In the steam turbine the steam instead of being expanded against a piston
is made to expand against and to get up velocity in itself. The jet of steam is
then made to impinge against vanes or to react against the moving orifice
from which it issues, in either of which cases its velocity and energy are
more or less completely abstracted and appropriated by the revolving
member. The Parsons turbine utilizes a combination of these two methods.

FIG. 34
Fig. 34 is a sectional view of the standard Westinghouse-Parsons single-
flow turbine. A photograph of the rotor R R R is reproduced in Fig. 35,
while in Fig. 36 a section of the blading is shown upon a larger scale.
Between the rows of the blading upon the rotor extend similar rows of
stationary blades attached to the casing or stator. The steam entering at A
(Fig. 34), fills the circular space surrounding the rotor and passes first
through a row of stationary blades, 1 (Fig. 37), expanding from the initial
pressure P to the slightly lower pressure P1, and attaining by that expansion
a velocity with which it is directed upon the moving blade 2. In passing
through this row of blades it is further expanded from pressure P1 to P2 and
helps to push the moving blades along by the reaction of the force with
which it issues therefrom. Impinging upon the second row of stationary
blades 3, the direction of flow is diverted so as to make it impinge at a
favorable angle upon the second row of revolving blades 4, and the action is
continued until the steam is expanded to the pressure of the condenser or of
the medium into which the turbine finally exhausts. As the expansion
proceeds, the passages are made larger by increasing the length of the
blades and the diameter of the drums upon which they are carried in order
to accommodate the increasing volume.

FIG. 35

FIG. 36

FIG. 37

It is not necessary that the blades shall run close together, and the axial
clearance, that is the space lengthwise of the turbine between the revolving
and the stationary blades, varies from 1/8 to 1/2 inch; but in order that there
may not be excessive leakage over the tops of the blades, as shown, very
much exaggerated, in Fig. 38, the radial clearance, that is, the clearance
between the tops of the moving blades and the casing, and between the ends
of the stationary blades and the shell of the rotor, must be kept down to the
lowest practical amount, and varies, according to the size of the machine
and length of blade, from about 0.025 to 0.125 of an inch.

FIG. 38
In the passage A (Fig. 34) exists the initial pressure; in the passage B the
pressure after the steam has passed the first section or diameter of the rotor;
in the passage C after it has passed the second section. The pressure acting
upon the exposed faces of the rows of vanes would crowd the rotor to the
left. They are therefore balanced by pistons or "dummies" P P P revolving
with the shaft and exposing in the annular spaces B1 and C1 the same areas
as those of the blade sections which they are designed to balance. The same
pressure is maintained in B1 as in B, and in C1 as in C by connecting them
with equalizing pipes E E. The third equalizing pipe connects the back or
right-hand side of the largest dummy with the exhaust passage so that the
same pressure exists upon it as exists upon the exhaust end of the rotor.
These dummy pistons are shown at the near end of the rotor in Fig. 35.
They are grooved so as to form a labyrinth packing, the face of the casing
against which they run being grooved and brass strips inserted, as shown in
Fig. 39. The dummy pistons prevent leakage from A, B1 and C1 to the
condenser, and must, of course, run as closely as practicable to the rings in
the casing, the actual clearance being from about 0.005 to 0.015 of an inch,
again depending on the size of the machine.

FIG. 39
The axial adjustment is controlled by the device shown at T in Fig. 34
and on a larger scale in Fig. 40. The thrust bearing consists of two parts, T1
T2. Each consists of a cast-iron body in which are placed brass collars.
These collars fit into grooves C, turned in the shaft as shown. The halves of
the block are brought into position by means of screws S1 S2 acting on
levers L1 L2 and mounted in the bearing pedestal and cover. The screws are
provided with graduated heads which permit the respective halves of the
thrust bearing to be set within one one-thousandth of an inch.

FIG. 40
The upper screw S2 is set so that when the rotor exerts a light pressure
against it through the thrust block and lever the grooves in the balance
pistons are just unable to come in contact with the dummy strips in the
cylinder. The lower screw S1 is then adjusted to permit about 0.008 to 0.010
of an inch freedom for the collar between the grooves of the thrust bearing.
These bearings are carefully adjusted before the machine leaves the
shop, and to prevent either accidental or unauthorized changes of their
adjustment the adjusting screw heads are locked by the method shown in
Fig. 40. The screw cannot be revolved without sliding back the latch L3. To
do this the pin P4 must be withdrawn, for which purpose the bearing cover
must be removed.
In general this adjustment should not be changed except when there has
been some wear of the collars in the thrust bearing; nevertheless, it is a wise

precaution to go over the adjustment at intervals. The method of doing this
is as follows: The machine should have been in operation for some time so
as to be well and evenly heated and should be run at a reduced speed, say
10 per cent. of the normal, during the actual operation of making the
adjustment. Adjust the upper screw which, if tightened, would push the
spindle away from the thrust bearing toward the exhaust. Find a position for
this so that when the other screw is tightened the balance pistons can just be
heard to touch, and so the least change of position inward of the upper
screw will cause the contact to cease. To hear if the balance pistons are
touching, a short piece of hardwood should be placed against the cylinder
casing near the balance piston. If the ear is applied to the other end of the
piece of wood the contact of the balance pistons can be very easily detected.
The lower screw should then be loosened and the upper screw advanced
from five to fifteen one-thousandths, according to the machine, at which
position the latter may be considered to be set. The lower screw should then
be advanced until the under half of the thrust bearing pushes the rotor
against the other half of the thrust bearing, and from this position it should
be pushed back ten or more one-thousandths, to give freedom for the rotor
between the thrusts, and locked. A certain amount of care should be
exercised in setting the dummies, to avoid straining the parts and thus
obtain a false setting.
The object in view is to have the grooves of the balance pistons running
as close as possible to the collars in the cylinder, but without danger of their
coming in actual contact, and to allow as little freedom as possible in the
thrust bearing itself, but enough to be sure that it will not heat. The turbine
rotor itself has scarcely any end thrust, so that all the thrust bearing has to
do is to maintain the above-prescribed adjustment.
The blades are so gaged that at all loads the rotor has a very light but
positive thrust toward the running face of the dummy strips, thus
maintaining the proper clearance at the dummies as determined by the
setting of the proper screw adjustment.

M ai n B e ar i ngs
The bearings which support the rotor are shown at F F in Fig. 34 and in
detail in Fig. 41. The bearing proper consists of a brass tube B with proper
oil grooves. It has a dowel arm L which fits into a corresponding recess in
the bearing cover and which prevents the bearing from turning. On this tube
are three concentric tubes, C D E, each fitting over the other with some
clearance so that the shaft is free to move slightly in any direction. These
tubes are held in place by the nut F, and this nut, in turn, is held by the
small set-screw G. The bearing with the surrounding tubes is placed inside
of the cast-iron shell A, which rests in the bearing pedestal on the block and
liner H. The packing ring M prevents the leakage of oil past the bearing. Oil
enters the chamber at one end of the bearing at the top and passes through
the oil grooves, lubricating the journal, and then out into the reservoir under
the bearing. The oil also fills the clearance between the tubes and forms a
cushion, which dampens any tendency to vibration.

FIG. 41

The bearings, being supported by the blocks or "pads" H, are self-
alining. Under these pads are liners 5, 10, 20, and 50 thousandths in
thickness. By means of these liners the rotor may be set in its proper
running position relative to the stator. This operation is quite simple.
Remove the liners from under one bearing pad and place them under the
opposite pad until a blade touch is obtained by turning the rotor over by
hand. After a touch has been obtained on the top, bottom, and both sides,
the total radial blade clearance will be known to equal the thickness of the
liners transferred. The position of the rotor is then so adjusted that the radial
blade clearance is equalized when the turbine is at operating temperature.

On turbines running at 1800 revolutions per minute or under, a split
babbitted bearing is used, as shown in Figs. 42a and 42b. These bearings
are self-alining and have the same liner adjustment as the concentric-sleeve
bearings just described. Oil is supplied through a hole D in the lower liner
pad, and is carried to the oil groove F through the tubes E E. The oil flows
from the middle of this bearing to both ends instead of from one end to the
other, as in the other type.

FIG. 42A

FIG. 42B

P a cki ng G l a nds
Where the shaft passes through the casing at either end it issues from a
chamber in which there exists a vacuum. It is necessary to pack the shaft at
these points, therefore, against the atmospheric pressure, and this is done by
means of a water-gland packing W W (Fig. 34). Upon the shaft in Fig. 35,
just in front of the dummy pistons, will be seen a runner of this packing
gland, which runner is shown upon a larger scale and from a different
direction in Fig. 43. To get into the casing the air would have to enter the
guard at A (Fig. 44), pass over the projecting rings B, the function of which
is to throw off any water which may be creeping along the shaft by
centrifugal force into the surrounding space C, whence it escapes by the
drip pipe D, hence over the five rings of the labyrinth packing E and thence
over the top of the revolving blade wheel, it being apparent from Fig. 43
that there is no way for the air to pass by without going up over the top of
the blades; but water is admitted to the centrally grooved space through the
pipe shown, and is revolved with the wheel at such velocity that the
pressure due to centrifugal force exceeds that of the atmosphere, so that it is
impossible for the air to force the water aside and leak in over the tips of the
blades, while the action of the runner in throwing the water out would
relieve the pressure at the shafts and avoid the tendency of the water to leak
outward through the labyrinth packing either into the vacuum or the
atmosphere.

FIG. 43

FIG. 44

The water should come to the glands under a head of about 10 feet, or a
pressure of about 5 pounds, and be connected in such a way that this
pressure may be uninterruptedly maintained. Its temperature must be lower
than the temperature due to the vacuum within the turbine, or it will
evaporate readily and find its way into the turbine in the form of steam.

FIG. 45
In any case a small amount of the steaming water will pass by the gland
collars into the turbine, so that if the condensed steam is to be returned to
the boilers the water used in the glands must be of such character that it
may be safely used for feed water. But whether the water so used is to be
returned to the boilers or not it should never contain an excessive amount of
lime or solid matter, as a certain amount of evaporation is continually going

on in the glands which will result in the deposit of scale and require
frequent taking apart for cleaning.

FIG. 46
When there is an ample supply of good, clean water the glands may be
packed as in Fig. 45, the standpipe supplying the necessary head and the
supply valve being opened sufficiently to maintain a small stream at the
overflow. When water is expensive and the overflow must be avoided, a
small float may be used as in Fig. 46, the ordinary tank used by plumbers
for closets, etc., serving the purpose admirably.

When the same water that is supplied to the glands is used for the oil-
cooling coils, which will be described in detail later, the coils may be
attached to either of the above arrangements as shown in Fig. 47.

FIG. 47
When the only available supply of pure water is that for the boiler feed,
and the condensed steam is pumped directly back to the boiler, as shown in
Fig. 48, the delivery from the condensed-water pumps may be carried to an
elevation 10 feet above the axis of the glands, where a tank should be
provided of sufficient capacity that the water may have time to cool
considerably before being used. In most of these cases, if so desired, the oil-
cooling water may come from the circulating pumps of the condenser,
provided there is sufficient pressure to produce circulation, as is also shown
in Fig. 48.

FIG. 48
When the turbine is required to exhaust against a back pressure of one or
two pounds a slightly different arrangement of piping must be made. The
water in this case must be allowed to circulate through the glands in order
to keep the temperature below 212 degrees Fahrenheit. If this is not done
the water in the glands will absorb heat from the main castings of the
machine and will evaporate. This evaporation will make the glands appear
as though they were leaking badly. In reality it is nothing more than the
water in the glands boiling, but it is nevertheless equally objectionable. This
may be overcome by the arrangement shown in Fig. 49, where two
connections and valves are furnished at M and N, which drain away to any
suitable tank or sewer. These valves are open just enough to keep sufficient
circulation so that there is no evaporation going on, which is evidenced by

steam coming out as though the glands were leaking. These circulating
valves may be used with any of the arrangements above described.

FIG. 49

T he G ove rn or
On the right-hand end of the main shaft in Fig. 34 there will be seen a worm
gear driving the governor. This is shown on a larger scale at A (Fig. 50). At
the left of the worm gear is a bevel gear driving the spindle D of the
governor, and at the right an eccentric which gives a vibratory motion to the
lever F. The crank C upon the end of the shaft operates the oil pump. The
speed of the turbine is controlled by admitting the steam in puffs of greater
or less duration according to the load. The lever F, having its fulcrum in the
collar surrounding the shaft, operates with each vibration of the eccentric
the pilot valve. The valve is explained in detail later.

FIG. 50
This form of governor has been superseded by an improved type, but so
many have been made that it will be well to describe its construction and
adjustment. The two balls W W (Fig. 50) are mounted on the ends of bell
cranks N, which rest on knife edges. The other end of the bell cranks carry
rollers upon which rest a plate P, which serves as a support for the governor
spring S. They are also attached by links to a yoke and sleeve E which acts
as a fulcrum for the lever F. The governor is regulated by means of the
spring S resting on the plate P and compressed by a large nut G on the
upper end of the governor spindle, which nut turns on a threaded quill J,
held in place by the nut H on the end of the governor spindle and is held
tight by the lock-nut K. To change the compression of the spring and
thereby the speed of the turbine the lock-nut must first be loosened and the
hand-nut raised to lower the speed or lowered to raise the speed as the case
may be. This operation may be accomplished while the machine is either
running or at rest.
The plate P rests upon ball bearings so that by simply bringing pressure
to bear upon the hand-wheel, which is a part of the quill J, the spring and
lock-nut may be held at rest and adjusted while the rest of the turbine
remains unaffected. Another lever is mounted upon the yoke E on the pin
shown at I, the other end of which is fastened to the piston of a dash-pot so
as to dampen the governor against vibration. Under the yoke E will be
noticed a small trigger M which is used to hold the governor in the full-load
position when the turbine is at rest.
The throwing out of the weights elevates the sleeve E, carrying with it
the collar C, which is spanned by the lever F upon the shaft H. The later
turbines are provided with an improved form of governor operating on the
same principle, but embodying several important features. First, the spindle
sleeve is integral with the governor yoke, and the whole rotates about a
vertical stationary spindle, so that two motions are encountered—a rotary
motion and an up and down motion, according to the position taken by the
governor. This spiral motion almost entirely eliminates the effect of friction

of rest, and thereby enhances the sensitiveness of the governor. Second, the
governor weights move outward on a parallel motion opposed directly by
spring thrust, thus relieving the fulcrum entirely of spring thrust. Third, the
lay shaft driving the governor oil pump and reciprocator is located
underneath the main turbine shaft, so that the rotor may be readily removed
without in the least disturbing the governor adjustment.

T h e V alve -G e a r
The valve-gear is shown in section in Fig. 51, the main admission being
shown at V1 at the right, and the secondary V2 at the left of the steam inlet.
The pilot valve F receives a constant reciprocating motion from the
eccentric upon the layshaft of the turbine through the lever F (Fig. 50).
These reciprocations run from 150 to 180 per minute. The space beneath the
piston C is in communication with the large steam chest, where exists the
initial pressure through the port A; the admission of steam to the piston C
being controlled by a needle valve B. The pilot valve connects the port E,
leading from the space beneath the piston to an exhaust port I.

FIG. 51
When the pilot valve is closed, the pressures can accumulate beneath the
piston C and raise the main admission valve from its seat. When the pilot
valve opens, the pressure beneath the piston is relieved and it is seated by
the helical spring above. If the fulcrum E (Fig. 50) of the lever F were fixed
the admission would be of an equal and fixed duration. But if the governor
raises the fulcrum E, the pilot valve F (Fig. 51) will be lowered, changing
the relations of the openings with the working edges of the ports.

The seating of the main admission valve is cushioned by the dashpot, the
piston of which is shown in section at G (Fig. 51). The valve may be
opened by hand by means of the lever K, to see if it is perfectly free.
The secondary valve is somewhat different in its action. Steam is
admitted to both sides of its actuating piston through the needle valves M
M, and the chamber from which this steam is taken is connected with the
under side of the main admission valve, so that no steam can reach the
actuating piston of the secondary valve until it has passed through the
primary valve. When the pilot valve is closed, the pressures equalize above

and below the piston N and the valve remains upon its seat. When the load
upon the turbine exceeds its rated capacity, the pilot valve moves upward so
as to connect the space above the piston with the exhaust L, relieving the
pressure upon the upper side and allowing the greater pressure below to
force the valve open, which admits steam to the secondary stage of the
turbine.
It would do no good to admit more steam to the first stage, for at the
rated capacity that stage is taking all the steam for which the blade area will
afford a passage. The port connecting the upper side of the piston N with
the exhaust may be permanently closed by means of the hand valve Q, to be
found on the side of the secondary pilot valve chest, thus cutting the
secondary valve entirely out of action. No dashpot is necessary on this
valve, the compression of the steam in the chamber W by the fall of the
piston being sufficient to avoid shock.
The timing of the secondary valve is adjusted by raising or lowering the
pilot valve by means of the adjustment provided. It should open soon
enough so that there will not be an appreciable drop in speed before the
valve comes into play. The economy of the machine will be impaired if the
valve is allowed to open too soon.

S a f e t y S top G o ve r no r
This device is mounted on the governor end of the turbine shaft, as shown
in Figs. 52 and 53. When the speed reaches a predetermined limit, the
plunger A, having its center of gravity slightly displaced from the center of
rotation of the shaft, is thrown radially outward and strikes the lever B. It
will easily be understood that when the plunger starts outward, the
resistance of spring C is rapidly overcome, since the centrifugal force
increases as the square of the radius, or in this case the eccentricity of the
center of gravity relative to the center of rotation. Hence, the lever is struck
a sharp blow. This releases the trip E on the outside of the governor casing,
and so opens the steam valve F, which releases steam from beneath the

actuating piston of a quick-closing throttle valve, located in the steam line.
Thus, within a period of usually less than one second, the steam is entirely
shut off from the turbine when the speed has exceeded 7 or 8 per cent of the
normal.

FIG. 52

FIG. 53

T h e O i l i ng S ys t e m
Mounted on the end of the bedplate is the oil pump, operated from the main
shaft of the turbine as previously stated. This may be of the plunger type
shown in Fig. 54, or upon the latest turbine, the rotary type shown in Fig.
55. Around the bedplate are located the oil-cooling coils, the oil strainer, the
oil reservoir and the oil pipings to the bearing.

FIG. 54
The oil reservoir, cooler, and piping are all outside the machine and
easily accessible for cleaning. Usually a corrugated-steel floor plate covers
all this apparatus, so that it will not be unsightly and accumulate dirt,

particularly when the turbine is installed, so that all this apparatus is below
the floor level; i.e., when the top of the bedplate comes flush with the floor
line. In cases where the turbine is set higher, a casing is usually built around
this material so that it can be easily removed, and forms a platform
alongside the machine.

FIG. 55

FIG. 56

The oil cooler, shown in Fig. 56, is of the counter-current type, the water
entering at A and leaving at B, oil entering at C (opening not shown) and
leaving at D. The coils are of seamless drawn copper, and attached to the
cover by coupling the nut. The water manifold F is divided into
compartments by transverse ribs, each compartment connecting the inlet of
each coil with the outlet of the preceding coil, thus placing all coils in
series. These coils are removable in one piece with the coverplate without
disturbing the rest of the oil piping.

B l ad i ng

FIG. 57
The blades are drawn from a rod consisting of a steel core coated with
copper so intimately connected with the other metal that when the bar is
drawn to the section required for the blading, the exterior coating drawn
with the rest of the bar forms a covering of uniform thickness as shown in
Fig. 57. The bar after being drawn through the correct section is cut into
suitable lengths punched as at A (Fig. 58), near the top of the blade, and has
a groove shown at B (Fig. 59), near the root, stamped in its concave face,
while the blade is being cut to length and punched. The blades are then set
into grooves cut into the rotor drum or the concave surface of the casing,
and spacing or packing pieces C (Fig. 59) placed between them. These
spacing pieces are of soft iron and of the form which is desired that the
passage between the blades shall take. The groove made upon the inner face
of the blade is sufficiently near to the root to be covered by this spacing
piece. When the groove has been filled the soft-iron pieces are calked or
spread so as to hold the blades firmly in place. A wire of comma section, as
shown at A (Fig. 59), is then strung through the punches near the outer ends
of the blades and upset or turned over as shown at the right in Fig. 58. This
upsetting is done by a tool which shears the tail of the comma at the proper
width between the blades. The bent-down portion on either side of the blade

holds it rigidly in position and the portion retained within the width of the
blade would retain the blade in its radial position should it become loosened
or broken off at the root. This comma lashing, as it is called, takes up a
small proportion only of the blade length or projection and makes a job
which is surprisingly stiff and rigid, and yet which yields in case of serious
disturbance rather than to maintain a contact which would result in its own
fusing or the destruction of some more important member.

FIG. 58

FIG. 59

S ta rt i ng U p t he T u rb i n e
When starting up the turbine for the first time, or after any extended period
of idleness, special care must be taken to see that everything is in good
condition and that all parts of the machine are clean and free from injury.
The oil piping should be thoroughly inspected and cleaned out if there is
any accumulation of dirt. The oil reservoirs must be very carefully wiped
out and minutely examined for the presence of any grit. (Avoid using cotton
waste for this, as a considerable quantity of lint is almost sure to be left
behind and this will clog up the oil passages in the bearings and strainer.)
The pilot valves should be removed from the barrel and wiped off, and
the barrels themselves cleaned out by pushing a soft cloth through them
with a piece of wood. In no case should any metal be used.
If the turbine has been in a place where there was dirt or where there has
been much dust blowing around, the bearings should be removed from the
spindle and taken apart and thoroughly cleaned. With care this can be done
without removing the spindle from the cylinder, by taking off the bearing
covers and very carefully lifting the weight of the spindle off the bearings,
then sliding back the bearings. It is best to lift the spindle by means of jacks

and a rope sling, as, if a crane is used, there is great danger of lifting the
spindle too high and thereby straining it or injuring the blades. After all the
parts have been carefully gone over and cleaned, the oil for the bearing
lubrication should be put into the reservoirs by pouring it into the governor
gear case G (Fig. 34). Enough oil should be put in so that when the
governor, gear case, and all the bearing-supply pipes are full, the supply to
the oil pump is well covered.
Special care should be taken so that no grit gets into the oil when
pouring it into the machine. Considerable trouble may be saved in this
respect by pouring the oil through cloth.
A very careful inspection of the steam piping is necessary before the
turbine is run. If possible it should be blown out by steam from the boilers
before it is finally connected to the turbine. Considerable annoyance may
result by neglecting this precaution, from particles of scale, red lead, gasket,
etc., out of the steam pipe, closing up the passages of the guide blades.
When starting up, always begin to revolve the spindle without vacuum
being on the turbine. After the spindle is turning slowly, bring the vacuum
up. The reason for this is, that when the turbine is standing still, the glands
do not pack and air in considerable quantity will rush through the glands
and down through the exhaust pipe. This sometimes has the effect of
unequal cooling. In case the turbine is used in conjunction with its own
separate condenser, the circulating pump may be started up, then the turbine
revolved, and afterward the air pump put in operation; then, last, put the
turbine up to speed. In cases, however, where the turbine exhausts into the
same condenser with other machinery and the condenser is therefore
already in operation, the valve between the turbine and the condenser
system should be kept closed until after the turbine is revolved, the turbine
in the meantime exhausting through the relief valve to atmosphere.
Care must always be taken to see that the turbine is properly warmed up
before being caused to revolve, but in cases where high superheat is
employed always revolve the turbine just as soon as it is moderately hot,
and before it has time to become exposed to superheat.

In the case of highly superheated steam, it is not undesirable to provide a
connection in the steam line by means of which the turbine may be started
up with saturated steam and the superheat gradually applied after the shaft
has been permitted to revolve.
For warming up, it is usual practice to set the governor on the trigger
(see Fig. 50) and open the throttle valve to allow the entrance of a small
amount of steam.
It is always well to let the turbine operate at a reduced speed for a time,
until there is assurance that the condenser and auxiliaries are in proper
working order, that the oil pump is working properly, and that there is no
sticking in the governor or the valve gear.
After the turbine is up to speed and on the governor, it is well to count
the speed by counting the strokes of the pump rod, as it is possible that the
adjustment of the governor may have become changed while the machine
has been idle. It is well at this time, while there is no load on the turbine, to
be sure that the governor controls the machine with the throttle wide open.
It might be that the main poppet valve has sustained some injury not evident
on inspection, or was leaking badly. Should there be some such defect, steps
should be taken to regrind the valve to its seat at the first opportunity.
On the larger machines an auxiliary oil pump is always furnished. This
should be used before starting up, so as to establish the oil circulation
before the turbine is revolved. After the turbine has reached speed, and the
main oil pump is found to be working properly, it should be possible to take
this pump out of service, and start it again only when the turbine is about to
be shut down.
If possible, the load should be thrown on gradually to obviate a sudden,
heavy demand upon the boiler, with its sometimes attendant priming and
rush of water into the steam pipe, which is very apt to take place if the load
is thrown on too suddenly. A slug of water will have the effect of slowing
down the turbine to a considerable extent, causing some annoyance. There
is not likely to be the danger of the damage that is almost sure to occur in

the reciprocating engine, but at the same time it is well to avoid this as
much as possible. A slug of water is obviously more dangerous when
superheated steam is being employed, owing to the extreme temperature
changes possible.

R unni ng
While the turbine is running, it should have a certain amount of careful
attention. This, of course, does not mean that the engineer must stand over it
every minute of the day, but he must frequently inspect such parts as the
lubricators, the oiling system, the water supply to the glands and the oil-
cooling coil, the pilot valve, etc. He must see that the oil is up in the
reservoir and showing in the gage glass provided for that purpose, and that
the oil is flowing freely through the bearings, by opening the pet cocks in
the top of the bearing covers. An ample supply of oil should always be in
the machine to keep the suction in the tank covered.

Care must be taken that the pump does not draw too much air. This can
usually be discovered by the bubbling up of the air in the governor case,
when more oil should be added.

It is well to note from time to time the temperature of the bearings, but
no alarm need be occasioned because they feel warm to the touch; in fact, a
bearing is all right as long as the hand can be borne upon it even
momentarily. The oil coming from the bearings should be preferably about
120 degrees Fahrenheit and never exceed 160 degrees.

It should generally be seen that the oil-cooling coil is effective in
keeping the oil cool. Sometimes the cooling water deposits mud on the
cooling surface, as well as the oil depositing a vaseline-like substance,
which interferes with the cooling effect. The bearing may become unduly
heated because of this, when the coil should be taken out at the first
opportunity and cleaned on the outside and blown out by steam on the
inside, if this latter is possible. If this does not reduce the temperature,

either the oil has been in use too long without being filtered, or the quality
of the oil is not good.

Should a bearing give trouble, the first symptom will be burning oil
which will smoke and give off dense white fumes which can be very readily
seen and smelled. However, trouble with the bearings is one of the most
unlikely things to be encountered, and, if it occurs, it is due to some radical
cause, such as the bearings being pinched by their caps, or grit and foreign
matter being allowed to get into the oil.

If a bearing gets hot, be assured that there is some very radical cause for
it which should be immediately discovered and removed. Never, under any
circumstances, imagine that you can nurse a bearing, that has heated, into
good behavior. Turbine bearings are either all right or all wrong. There are
no halfway measures.

The oil strainer should also be occasionally taken apart and thoroughly
cleaned, which operation may be performed, if necessary, while the turbine
is in operation. The screens should be cleaned by being removed from their
case and thoroughly blown out with steam. In the case of a new machine,
this may have to be done every two or three hours. In course of time, this
need only be repeated perhaps once a week. The amount of dirt found will
be an indication of the frequency with which this cleaning is necessary.
The proper water pressure, about five pounds per square inch, must be
maintained at the glands. Any failure of this will mean that there is some
big leak in the piping, or that the water is not flowing properly.

The pilot valve must be working freely, causing but little kick on the
governor, and should be lubricated from time to time with good oil.
Should it become necessary, while operating, to shut down the condenser
and change over to non-condensing operation, particular care should be
observed that the change is not made too suddenly to non-condensing, as all
the low-pressure sections of the turbine must be raised to a much higher
temperature. While this may not cause an accident, it is well to avoid the

stresses which necessarily result from the sudden change of temperature.
The same reasons, of course, do not hold good in changing from non-
condensing to condensing.

S h ut t i ng D own
When shutting down the turbine the load may be taken off before closing
the throttle; or, as in the case of a generator operating on an independent
load, the throttle may be closed first, allowing the load to act as a brake,
bringing the turbine to rest quickly. In most cases, however, the former
method will have to be used, as the turbine generally will have been
operating in parallel with one or more other generators. When this is the
case, partially close the throttle just before the load is to be thrown off, and
if the turbine is to run without load for some time, shut off the steam almost
entirely in order to prevent any chance of the turbine running away. There is
no danger of this unless the main valve has been damaged by the water
when wet steam has been used, or held open by some foreign substance,
when, in either case, there may be sufficient leakage to run the turbine
above speed, while running light. At the same time, danger is well guarded
against by the automatic stop valve, but it is always well to avoid a possible
danger. As soon as the throttle is shut, stop the condenser, or, in the case
where one condenser is used for two or more turbines, close the valve
between the turbine and the condenser. Also open the drains from the steam
strainer, etc. This will considerably reduce the time the turbine requires to
come to rest. Still more time may be saved by leaving the field current on
the generator.
Care should be taken, when the vacuum falls and the turbine slows
down, to see that the water is shut off from the glands for fear it may leak
out to such an extent as to let the water into the bearings and impair the
lubricating qualities of the oil.

I ns p e c t i o n
At regular intervals thorough inspection should be made of all parts of the
turbine. As often as it appears necessary from the temperature of the oil,
depending on the quality of the oil and the use of the turbine, remove the
oil-cooling coil and clean it both on the inside and outside as previously
directed; also clean out the chamber in which it is kept. Put in a fresh
supply of oil. This need not necessarily be new, but may be oil that has been
in use before but has been filtered. We recommend that an oil filter be kept
for this purpose. Entirely new oil need only be put into the turbine when the
old oil shows marked deterioration. With a first-class oil this will probably
be a very infrequent necessity, as some new oil has to be put in from time to
time to make up the losses from leakage and waste.

Clean out the oil strainer, blowing steam through the wire gauze to
remove any accumulation of dirt. Every six months to a year take off the
bearing covers, remove the bearings, and take them apart and clean out
thoroughly. Even the best oil will deposit more or less solid matter upon hot
surfaces in time, which will tend to prevent the free circulation of the oil
through the bearings and effectively stop the cushioning effect on the
bearings. Take apart the main and secondary valves and clean thoroughly,
seeing that all parts are in good working order. Clean and inspect the
governor and the valve-gear, wiping out any accumulation of oil and dirt
that may appear. Be sure to clean out the drains from the glands so that any
water that may pass out of them will run off freely and will not get into the
bearings.

At the end of the first three months, and after that about once a year, take
off the cylinder cover and remove the spindle. When the turbine is first
started up, there is very apt to be considerable foreign matter come over in
the steam, such as balls of red lead or small pieces of gasket too small to be
stopped by the strainer. These get into the guide blades in the cylinder and
quite effectively stop them up. Therefore, the blades should be gone over
very carefully, and any such additional accumulation removed. Examine the
glands and equilibrium ports for any dirt or broken parts. Particularly

examine the glands for any deposit of scale. All the scale should be chipped
off the gland parts, as, besides preventing the glands from properly packing,
this accumulation will cause mechanical contact and perhaps cause
vibration of the machine due to lack of freedom of the parts. The amount of
scale found after the first few inspections will be an indication of how
frequently the cleaning should be done. As is discussed later, any water that
is unsuitable for boiler feed should not be used in the glands.

In reassembling the spindle and cover, very great care must be taken that
no blades are damaged and that nothing gets into the blades. Nearly all the
damage that has been done to blades has resulted from carelessness in this
respect; in fact, it is impossible to be too careful. Particular care is also to be
taken in assembling all the parts and in handling them, as slight injury may
cause serious trouble. In no case should a damaged part be put back until
the injury has been repaired.

If for any reason damaged blades cannot be repaired at the time, they can
be easily removed and the turbine run again without them until it is
convenient to put in new ones; in fact, machines have been run at full load
with only three-quarters of the total number of blades. In such an event
remove the corresponding stationary blades as well as the moving blades,
so as not to disturb the balance of the end thrust.

C ond i t i o n s C onduc i ve to S ucc e s s f u l
O p e rat i o n
In the operation of the turbine and the conditions of the steam, both live and
exhaust play a very important part. It has been found by expensive
experimenting that moisture in the steam has a very decided effect on the
economy of operation; or considerably more so than in the case of the
reciprocating engine. In the latter engine, 2 per cent. of moisture will mean
very close to 2 per cent. increase in the amount of water supplied to the
engine for a given power. On the other hand, in the turbine 2 per cent.

moisture will cause an addition of more nearly 4 per cent. It is therefore
readily seen that the drier the entering steam, the better will be the
appearance of the coal bill.

By judicious use of first-class separators in connection with a suitable
draining system, such as the Holly system which returns the moisture
separated from the steam, back to the boilers, a high degree of quality may
be obtained at the turbine with practically no extra expense during
operation. Frequent attention should be given the separators and traps to
insure their proper operation. The quality of the steam may be determined
from time to time by the use of a throttling calorimeter. Dry steam, to a
great extent, depends upon the good and judicious design of steam piping.

Superheated steam is of great value where it can be produced
economically, as even a slight degree insures the benefits to be derived from
the use of dry steam. The higher superheats have been found to increase the
economy to a considerable extent.
When superheat of a high degree (100 degrees Fahrenheit or above) is
used special care must be exercised to prevent a sudden rise of the
superheat of any amount. The greatest source of trouble in this respect is
when a sudden demand is made for a large increase in the amount of steam
used by the engine, as when the turbine is started up and the superheater has
been in operation for some time before, the full load is suddenly thrown on.
It will be readily seen that with the turbine running light and the superheater
operating, there is a very small amount of steam passing through; in fact,
practically none, and this may become very highly heated in the
superheater, but loses nearly all its superheat in passing slowly to the
turbine; then, when a sudden demand is made, this very high temperature
steam is drawn into the turbine. This may usually be guarded against where
a separately fired superheater is used, by keeping the fire low until the load
comes on, or, in the case where the superheater is part of the boiler, by
either not starting up the superheater until after load comes on, or else
keeping the superheat down by mixing saturated steam with that which has
been superheated. After the plant has been started up there is little danger

from this source, but such precautions should be taken as seem best in the
particular cases.
Taking up the exhaust end of the turbine, we have a much more striking
departure from the conditions familiar in the reciprocating engine. Due to
the limits imposed upon the volume of the cylinder of the engine, any
increase in the vacuum over 23 or 24 inches, in the case, for instance, of a
compound-condensing engine, has very little, if any, effect on the economy
of the engine. With the turbine, on the other hand, any increase of vacuum,
even up to the highest limits, increases the economy to a very considerable
extent and, moreover, the higher the vacuum the greater will be the increase
in the economy for a given addition to the vacuum. Thus, raising the
vacuum from 27 to 28 inches has a greater effect than from 23 to 24 inches.
For this reason the engineer will readily perceive the great desirability of
maintaining the vacuum at the highest possible point consistent with the
satisfactory and economical operation of the condenser.

The exhaust pipe should always be carried downward to the condenser
when possible, to keep the water from backing up from the condenser into
the turbine. If the condenser must be located above the turbine, then the
pipe should be carried first downward and then upward in the U form, in the
manner of the familiar "entrainer," which will be found effectively to
prevent water getting back when the turbine is operating.

C o nde ns e r s
As has been previously pointed out, the successful and satisfactory
operation of the turbine depends very largely on the condenser. With the
reciprocating engine, if the condenser will give 25 inches vacuum, it is
considered fairly good, and it is allowed to run along by itself until the
vacuum drops to somewhere below 20 inches, when it is completely gone
over, and in many cases practically rebuilt and the vacuum brought back to
the original 25 inches. It has been seen that this sort of practice will never
do in the case of the turbine condenser and, unless the vacuum can be

regularly maintained at 27 or 28 inches, the condenser is not doing as well
as it ought to do, or it is not of the proper type, unless perhaps the
temperature and the quantity of cooling water available render a higher
vacuum unattainable.
On account of the great purity of the condensed steam from the turbine
and its peculiar availability for boiler feed (there being no oil of any kind
mixed with it to injure the boilers), the surface condenser is very desirable
in connection with the turbine. It further recommends itself by reason of the
high vacuum obtainable.

Where a condenser system capable of the highest vacuum is installed,
the need of utilizing it to its utmost capacity can hardly be emphasized too
strongly. A high vacuum will, of course, mean special care and attention,
and continual vigilance for air leaks in the exhaust piping, which will,
however, be fully paid for by the great increase in economy.

It must not be inferred that a high vacuum is essential to successful
operation of this type of turbine, for excellent performance both in the
matter of steam consumption and operation is obtained with inferior
vacuum. The choice of a condenser, however, is a matter of special
engineering, and is hardly within the province of this article.

Oils
There are several oils on the market that are suitable for the purpose of the
turbine oiling system, but great care must be exercised in their selection. In
the first place, the oil must be pure mineral, unadulterated with either
animal or vegetable oils, and must have been washed free from acid.
Certain brands of oil require the use of sulphuric acid in their manufacture
and are very apt to contain varying degrees of free acid in the finished
product. A sample from one lot may have almost no acid, while that from
another lot may contain a dangerous amount.

Mineral oils that have been adulterated, when heated up, will partially
decompose, forming acid. These oils may be very good lubricants when
first put into use, but after awhile they lose all their good qualities and
become very harmful to the machine by eating the journals in which they
are used. These oils must be very carefully avoided in the turbine, as the
cheapness of their first cost will in no way pay for the damage they may do.
A very good and simple way to test for such adulterations is to take up a
quantity of the oil in a test tube with a solution of borax and water. If there
is any animal or vegetable adulterant present it will appear as a white milk-
like emulsion which will separate out when allowed to stand. The pure
mineral oil will appear at the top as a clear liquid and the excess of the
borax solution at the bottom, the emulsion being in between. A number of
oils also contains a considerable amount of paraffin which is deposited in
the oil-cooling coil, preventing the oil from being cooled properly, and in
the pipes and bearings, choking the oil passages and preventing the proper
circulation of the oil and cushioning effect in the bearing tubes. This is not
entirely a prohibitive drawback, the chief objection being that it necessitates
quite frequently cleaning the cooling coil, and the oil piping and bearings.

Some high-class mineral oils of high viscosity are inclined to emulsify
with water, which emulsion appears as a jelly-like substance. It might be
added that high-grade oils having a high viscosity might not be the most
suitable for turbine use.
Since the consumption of oil in a turbine is so very small, being
practically due only to leakage or spilling, the price paid for it should
therefore be of secondary importance, the prime consideration being its
suitability for the purpose.

In some cases a central gravity system will be employed, instead of the
oil system furnished with the turbine, which, of course, will be a special
consideration.
For large installations a central gravity oiling system has much to
recommend it, but as it performs such an important function in the power
plant, and its failure would be the cause of so much damage, every detail in

connection with it should be most carefully thought out, and designed with
a view that under no combination of circumstances would it be possible for
the system to become inoperative. One of the great advantages of such a
system is that it can be designed to contain very large quantities of oil in the
settling tanks; thus the oil will have quite a long rest between the times of
its being used in the turbine, which seems to be very helpful in extending
the life of the oil. Where the oil can have a long rest for settling, an inferior
grade of oil may be used, providing, however, that it is absolutely free of
acid.

V. PROPER METHOD OF TESTING A
STEAM TURBINE [3]

[3] Contributed to Power by Thomas Franklin.

The condensing arrangements of a turbine are perhaps mainly
instrumental in determining the method of test. The condensed steam alone,
issuing from a turbine having, for example, a barometric or jet condenser,
cannot be directly measured or weighed, unless by meter, and these at
present are not sufficiently accurate to warrant their use for test purposes, if
anything more than approximate results are desired. The steam consumed
can, in such a case, only be arrived at by measuring the amount of
condensing water (which ultimately mingles with the condensed steam),
and subtracting this quantity from the condenser's total outflow.
Consequently, in the case of turbines equipped with barometric or jet
condensers, it is often thought sufficient to rely upon the measurement
taken of the boiler feed, and the boiler's initial and final contents. Turbines
equipped with surface-condensing plants offer better facilities for accurate
steam-consumption calculations than those plants in which the condensed
exhaust steam and the circulating water come into actual contact, it being
necessary with this type simply to pump the condensed steam into a
weighing or measuring tank.
In the case of a single-flow turbine of the Parsons type, the covers
should be taken off and every row of blades carefully examined for
deposits, mechanical irregularities, deflection from the true radial and
vertical positions, etc. The blade clearances also should be gaged all around
the circumference, to insure this clearance being an average working
minimum. On no account should a test be proceeded with when any doubt
exists as to the clearance dimensions.

FIG. 60

The dummy rings of a turbine, namely, those rings which prevent
excessive leakage past the balancing pistons at the high-pressure end,
should have especial attention before a test. A diagrammatic sketch of a
turbine cylinder and spindle is shown in Fig. 60, for the benefit of those
unfamiliar with the subject. In this A is the cylinder or casing, B the spindle
or rotor, and C the blades. The balancing pistons, D, E, and F, the pressure
upon which counterbalances the axial thrust upon the three-bladed stages,
are grooved, the brass dummy rings G G in the cylinder being alined within
a few thousandths of an inch of the grooved walls, as indicated. After these
rings have been turned (the turning being done after the rings have been
calked in the cylinder), it is necessary to insure that each ring is perfectly
bedded to its respective grooved wall so that when running the several
small clearances between the groove walls and rings are equal. A capital
method of thus bedding the dummy rings is to grind them down with a flour
of emery or carborundum, while the turbine spindle is slowly revolving
under steam. Under these conditions the operation is performed under a
high temperature, and any slight permanent warp the rings may take is thus
accounted for. The turbine thrust-block, which maintains the spindle in
correct position relatively to the spindle, may also be ground with
advantage in a similar manner.

The dummy rings are shown on a large scale in Fig. 61, and their
preliminary inspection may be made in the following manner:

The spindle has been set and the dummy rings C are consequently within
a few thousandths of an inch of the walls d of the spindle dummy grooves
D. The clearances allowed can be gaged by a feeler placed between a ring
and the groove wall. Before a test the spindle should be turned slowly
around, the feelers being kept in position. By this means any mechanical
flaws or irregularities in the groove walls may be detected.

FIG. 61

It has sometimes been found that the groove walls, under the combined
action of superheated steam and friction, in cases where actual running
contact has occurred, have worn very considerably, the wear taking the
form of a rapid crumbling away. It is possible, however, that such
deterioration may be due solely to the quality of the steel from which the
spindle is forged. Good low-percentage carbon-annealed steel ought to

withstand considerable friction; at all events the wear under any conditions
should be uniform. If the surfaces of both rings and grooves be found in bad
condition, they should be re-ground, if not sufficiently worn to warrant
skimming up with a tool.

As the question of dummy leakage is of very considerable importance
during a test, it may not be inadvisable to describe the manner of setting the
spindle and cylinder relatively to one another to insure minimum leakage,
and the methods of noting their conduct during a prolonged run. In Fig. 62,
showing the spindle, B is the thrust (made in halves), the rings O of which
fit into the grooved thrust-rings C in the spindle. Two lugs D are cast on
each half of the thrust-block. The inside faces of these lugs are machined,
and in them fit the ball ends of the levers E, the latter being fulcrumed at F
in the thrust-bearing cover. The screws G, working in bushes, also fit into
the thrust-bearing cover, and are capable of pushing against the ends of the
levers E and thus adjusting the separate halves of the block in opposite
directions.

FIG. 62

The top half of the turbine cylinder having been lifted off, the spindle is
set relatively to the bottom half by means of the lower thrust-block screw
G. This screw is then locked in position and the top half of the cover then
lowered into place. With this method great care must necessarily be
exercised when lowering the top cover; otherwise the brass dummy rings
may be damaged.

A safer method is to set the dummy rings in the center of the grooves of
the spindle, and then to lower the cover, with less possibility of contact.
There being usually plenty of side clearance between the blades of a
turbine, it may be deemed quite safe to lock the thrust-block in its position,

by screwing the screws G up lightly, and then to turn on steam and begin
running slowly.

Next, the spindle may be very carefully and gradually worked in the
required direction, namely, in that direction which will tend to bring the
dummy rings and groove walls into contact, until actual but very light
contact takes place. The slightest noise made by the rubbing parts inside the
turbine can be detected by placing one end of a metal rod onto the casing in
vicinity of the dummy pistons, and letting the other end press hard against
the ear. Contact between the dummy rings and spindle being thus
demonstrated, the spindle must be moved back by the screws, but only by
the slightest amount possible. The merest fraction of a turn is enough to
break the contact, which is all that is required. In performing this operation
it is important, during the axial movements of the spindle, to adjust the
halves of the thrust-block so that there can exist no possible play which
would leave the spindle free to move axially and probably vibrate badly.

After ascertaining the condition of the dummy rings, attention might
next be turned to the thrust-block, which must not on any account be
tightened up too much. It is sufficient to say that the actual requirements are
such as will enable a very thin film of oil to circulate between each wall of
the spindle thrust-grooves and the brass thrust-blocks ring. In other words,
there should be no actual pressure, irrespective of that exerted by the
spindle when running, upon the thrust-block rings, due to the separate
halves having been nipped too tightly. The results upon a test of
considerable friction between the spindle and thrust-rings are obvious.

The considerations outlined regarding balancing pistons and dummy
rings can be dispensed with in connection with impulse turbines of the De
Laval and Rateau types, and also with double-flow turbines of a type which
does not possess any dummies. The same general considerations respecting
blade conditions and thrust-blocks are applicable, especially to the latter
type. With pure so-called impulse turbines, where the blade clearances are
comparatively large, the preliminary blade inspection should be devoted to
the mechanical condition of the blade edges and passages. As the steam

velocities of these types are usually higher, the importance of minimizing
the skin friction and eliminating the possibility of eddies is great.

Although steam leakage through the valves of a turbine may not
materially affect its steam consumption, unless it be the leakage through the
overload valve during a run on normal full load, a thorough examination of
all valves is advocated for many reasons. In a turbine the main steam-inlet
valve is usually operated automatically from the governor; and whether it
be of the pulsating type, admitting the steam in blasts, or of the non-
pulsating throttling type, it is equally essential to obtain the least possible
friction between all moving and stationary parts. Similar remarks apply to
the main governor, and any sensitive transmitting mechanism connecting it
with any of the turbine valves. If a safety or "runaway" governor is
possessed by the machine to be tested, this should invariably be tried under
the requisite conditions before proceeding farther. The object of this
governor being automatically to shut off all steam from the turbine, should
the latter through any cause rise above the normal speed, it is often set to
operate at about 12 to 15 per cent. above the normal. Thus, a turbine
revolving at about 3000 revolutions per minute would be closed down at,
say, 3500, which would be within the limit of "safe" speed.

I mp orta n c e o f O i l i n g S ys t e m an d W at e r
S e rvi ce
The oil question, being important, should be solved in the early stages
previously, if possible, to any official or unofficial consumption tests.
Whether the oil be supplied to the turbine bearings by a self-contained
system having the oil stored in the turbine bedplate or by gravity from a
separate oil source, does not affect the question in its present aspect. The
necessary points to investigate are four in number, and may be headed as
follows:
(a) Examination of pipes and partitions for oil leakage.

(b) Determination of volume of oil flowing through each bearing per unit of
time.
(c) Examination for signs of water in oil.
(d) Determination of temperature rise between inlet and outlet of oil
bearings.
The turbine supplied with oil by the gravity or any other separate system
holds an advantage over the ordinary self-contained machine, inasmuch as
the oil pipes conveying oil into and from the bearings can be easily
approached and, if necessary, repaired. On the other hand, the machine
possessing its own oil tank, cooling chamber and pump is somewhat at a
disadvantage in this respect, as a part of the system is necessarily hidden
from view, and, further, it is not easily accessible. The leakage taking place
in any system, if there be any, must, however, be detected and stopped.

Fig. 63 is given to illustrate a danger peculiar to the self-contained oil
system, in which the oil and oil-cooling chambers are situated adjacently in
the turbine bedplate. One end of the bedplate only is shown; B is a cast-iron
partition dividing the oil chamber C from the oil-cooling chamber D.
Castings of this kind have sometimes a tendency to sponginess and the
trouble consequent upon this weakness would take the form of leakage
between the two chambers. Of course this is only a special case, and the
conditions named are hardly likely to exist in every similarly designed
plant. The capacity of oil, and especially of hot oil, to percolate through the
most minute pores is well known. Consequently, in advocating extreme
caution when dealing with oil leakage, no apology is needed.

FIG. 63

It may be stated without fear of contradiction that the oil in a self-
contained system, namely, a system in which the oil, stored in a reservoir
near or underneath the turbine, passes only through that one turbine's
bearings, and immediately back to the storage compartment, deteriorates
more rapidly than when circulating around an "entire" system, such as the
gravity or other analogous system. In the latter, the oil tanks are usually
placed a considerable distance from the turbine or turbines, with the oil-
cooling arrangements in fairly close proximity. The total length of the oil
circuit is thus considerably increased, incidentally increasing the relative
cooling capacity of the whole plant, and thereby reducing the loss of oil by
vaporization.

The amount of oil passing through the bearings can be ascertained
accurately by measurement. With a system such as the gravity it is only
necessary to run the turbine up to speed, turn on the oil, and then, over a
period, calculate the volume of oil used by measuring the fall of level in the
storage tank and multiplying by its known cross-sectional area. In those
cases where the return oil, after passing through the bearings, is delivered
back into the same tank from which it is extracted, it is of course necessary,
during the period of test, to divert this return into a separate temporary

receptacle. Where the system possesses two tanks, one delivery and one
return (a superior arrangement), this additional work is unnecessary. The
same method can be applied to individual turbines pumping their own oil
from a tank in the bedplate; the return oil, as previously described, being
temporarily prevented from running back to the supply.

The causes of excessive oil consumption by bearings are many. There is
an economical mean velocity at which the oil must flow along the revolving
spindle; also an economical mean pressure, the latter diminishing from the
center of the bearing toward the ends. The aim of the economist must
therefore be in the direction of adjusting these quantities correctly in
relation to a minimum supply of oil per bearing; and the principal factors
capable of variation to attain certain requirements are the several bearing
clearances measured as annular orifices, and the bearing diameters.
It is not always an easy matter to detect the presence of water in an oil
system, and this difficulty is increased in large circuits, as the water, when
the oil is not flowing, generally filters to the lowest members and pipes of
the system, where it cannot usually be seen. A considerable quantity of
water in any system, however, indicates its presence by small globular
deposits on bearings and spindles, and in the worst cases the water can
clearly be seen in a small sample tapped from the oil mains. There is only
one effective method of ridding the oil of this water, and this is by allowing
the whole mass of oil in the system to remain quiescent for a few days, after
which the water, which falls to the lowest parts, can be drained off. A
simple method of clearing out the system is to pump all the oil the whole
circuit contains through the filters, and thence to a tank from which all
water can be taken off. One of the ordinary supply tanks used in the gravity
system will serve this purpose, should a temporary tank not be at hand. If
necessary, the headers and auxiliary pipes of the system can be cleaned out
before circulating the oil again, but as this is rather a large undertaking, it
need only be resorted to in serious cases.

FIG. 64
It is seldom possible to discover the correct and permanent temperature
rise of the circulating oil in a turbine within the limited time usually alloted
for a test. After a continuous run of one hundred hours it is possible that the
temperature at the bearing outlets may be lower than it was after the
machine had run for, say, only twenty hours. As a matter of fact an oil-
temperature curve plotted from periodical readings taken over a continuous
run of considerable length usually reaches a maximum early, afterward
falling to a temperature about which the fluctuations are only slight during
the remainder of the run. Fig. 64 illustrates an oil-temperature curve plotted
from readings taken over a period of twenty-four hours. In this case the oil
system was of the gravity description, the capacity of the turbine being
about 6000 kilowatts. The bearings were of the ordinary white-metal
spherical type. Over extended runs of hundreds and even thousands of
hours, the above deductions may be scarcely applicable. Running without
break for so long, a small turbine circulating its own lubricant would
possibly require a renewal of the oil before the run was completed, in the
main owing to excessive temperature rise and consequent deterioration of
the quality of the oil. Under these conditions the probabilities are that

several temperature fluctuations might occur before the final maximum, and
more or less constant, temperature was reached. In this connection,
however, the results obtained are to a very large extent determined by the
general mechanical design and construction of the oiling system and
turbine. A reference to Fig. 63 again reveals at once a weakness in that
design, namely, the unnecessarily close proximity in which the oil and
water tanks are placed.

FIG. 65

A design of thermometer cup suitable for oil thermometers is given in
Fig. 65 in which A is an end view of the turbine bedplate, B is a turbine
bearing and C and D are the inlet and outlet pipes, respectively. The

thermometer fittings, which are placed as near the bearing as is practicable,
are made in the form of an angular tee fitting, the oil pipes being screwed
into its ends. The construction of the oil cup and tee piece is shown in the
detail at the left where A is the steel tee piece, into which is screwed the
brass thermometer cup B. The hollow bottom portion of this cup is less than
1/16 of an inch in thickness. The top portion of the bored hole is enlarged as
shown, and into this, around the thermometer, is placed a non-conducting
material. The cup itself is generally filled with a thin oil of good
conductance.

Allied to the oil system of a turbine plant is the water service, of
comparatively little importance in connection with single self-contained
units of small capacity, where the entire service simply consists of a few
coils and pipes, but of the first consideration in large installations having
numerous separate units supplied by oil and water from an exterior source.
The largest turbine units are often supplied with water for cooling the
bearings and other parts liable to attain high temperature. Although the
water used for cooling the bearings indirectly supplements the action taking
place in the separate oil coolers, it is of necessity a separate auxiliary
service in itself, and the complexity of the system is thus added to. A
carefully constructed water service, however, is hardly likely to give trouble
of a mechanical nature. The more serious deficiencies usually arise from
conditions inherent to the design, and as such must be approached.

S p e c i a l T u r b i n e F e at ur e s to be I nqu i r e d i nto
Before leaving the prime mover itself, and proceeding to the auxiliary plant
inspection, it may be well to instance a few special features relating to the
general conduct of a turbine, which it is the duty of a tester to inquire into.
There are certain specified qualifications which a machine must hold when
running under its commercial conditions, among these being lack of
vibration of both turbine and machinery driven, be it generator or fan, the
satisfactory running of auxiliary turbine parts directly driven from the

turbine spindle, minimum friction between the driving mediums, such as
worm-wheels, pumps, fans, etc., slight irregularities of construction, often
resulting in heated parts and excessive friction and wear, and must therefore
be detected and righted before the final test. Furthermore, those features of
design—and they are not infrequent in many machines of recent
development—which, in practice, do not fulfil theoretical expectations,
must be re-designed upon lines of practical consistency. The experienced
tester's opinion is often at this point invaluable. To illustrate the foregoing,
Figs. 66, 67, and 68 are given, representing, respectively, three distinct
phases in the evolution of a turbine part, namely, the coupling. Briefly, an
ordinary coupling connecting a driving and a driven shaft becomes
obstinate when the two separate spindles which it connects are not truly
alined. The desire of turbine manufacturers has consequently been to design
a flexible coupling, capable of accommodating a certain want of alinement
between the two spindles without in any way affecting the smooth running
of the whole unit.

FIG. 66

Fig. 67
In Fig. 66 A is the turbine spindle end and B the generator spindle end,
which it is required to drive. It will be seen from the cross-sectional end

view that both spindle ends are squared, the coupling C, with a square hole
running through it, fitting accurately over both spindle ends as shown.
Obviously the fit between the coupling and spindle in this case must be
close, otherwise considerable wear would take place; and equally obvious is
the fact than any want of alinement between the two spindles A and B will
be accompanied by a severe strain upon the coupling, and incidentally by
many other troubles of operation of which this inability of the coupling to
accommodate itself to a little want of alinement is the inherent cause.
Looking at the coupling illustrated in Fig. 67, it will be seen that
something here is much better adapted to dealing with troubles of
alinement. The turbine and generator spindles A and B, respectively, are
coned at the ends, and upon these tapered portions are shrunk circular heads
C and D having teeth upon their outer circumferences. Made in halves, and
fitting over the heads, is a sleeve-piece, with teeth cut into its inner bored
face. The teeth of the heads and sleeve are proportioned correctly to
withstand, without strain, the greatest pressure liable to be thrown upon
them. There is practically no play between the teeth, but there exists a small
annular clearance between the periphery of the heads and the inside bore of
the sleeve, which allows a slight lack of alinement to exist between the two
spindles, without any strain whatever being felt by the coupling sleeve E.
The nuts F and G prevent any lateral movement of the coupling heads C
and D. For all practical requirements this type of coupling is satisfactory, as
the clearances allowed between sliding sleeve and coupling heads can
always be made sufficient to accommodate a considerable want of
alinement, far beyond anything which is likely to occur in actual practice.
Perhaps the only feature against it is its lack of simplicity of construction
and corresponding costliness.

FIG. 68
The type illustrated in Fig. 68 is a distinct advance upon either of the
two previous examples, because, theoretically at least, it is capable of
successfully accommodating almost any amount of spindle movement. The
turbine and generator spindle ends, A and B, have toothed heads C and D
shrunk upon them, the heads being secured by the nuts E and F. The teeth
in this case are cut in the enlarged ends as shown. A sleeve G, made in
halves, fits over the heads, and the teeth cut in each half engage with those
of their respective heads. All the teeth and teeth faces are cut radially, and a
little side play is allowed.

T h e C onde ns e r
To some extent, as previously remarked, the condenser and condensing
arrangements are instrumental in determining the lines upon which a test
ought to be carried out. In general, the local features of a plant restrict the
tester more or less in the application of his general methods. A thorough
inspection, including some preliminary tests if necessary, is as essential to
the good conduct of the condensing plant as to the turbine above it. It may
be interesting to outline the usual course this inspection takes, and to draw
attention to a few of the special features of different plants. For this purpose
a type of vertical condenser is depicted in Fig. 69. Its general principle will
be gathered from the following description:

Exhaust steam from the turbine flows down the pipe T and enters the
condenser at the top as shown, where it at once comes into contact with the
water tubes in W. These tubes fill an annular area, the central un-tubed
portion below the baffle cap B forming the vapor chamber. The condensed
steam falls upon the bottom tube-plate P and is carried away by the pipe S
leading to the water pump H. The Y pipe E terminating above the level of
the water in the condenser enters the dry-air pump section pipe A. Cold
circulating water enters the condenser at the bottom, through the pipe I, and
entering the water chamber X proceeds upward through the tubes into the
top-water chamber Y, and from there out of the condenser through the exit
pipe. It will be observed that the vapor extracted through the plate P passes
on its journey out of the condenser through the cooling chamber D
surrounded by the cold circulating water. This, of course, is a very
advantageous feature. At R is the condenser relief, at U the relief valve for
the water chambers.

FIG. 69
A new condenser, especially if it embody new and untried features,
generally requires a little time and patience ere the best results can be
obtained from it. Perhaps the quickest and most satisfactory method of
getting at the weak points of this portion of a plant is to test the various
elements individually before applying a strict load test. Thus, in dealing
with a condenser similar to that illustrated in Fig. 69, the careful tester

would probably make, in addition to a thorough mechanical examination,
three or four individual vacuum and water tests. A brief description of these
will be given. The water test, the purpose of which is to discover any
leakage from the tubes, tube-plates, water pipes, etc., into portions of the
steam or air chambers, should be made first.

W at e r T e s t s of C onde ns e r
The condenser is first thoroughly dried out, particular care being given to
the outside of the tubes and the bottom tube-plate P. Water is then
circulated through the tubes and chambers for an hour or two, after which
the pumps are stopped, all water is allowed to drain out and a careful
examination is made inside. Any water leaking from the tubes above the
bottom baffle-plate will ultimately be deposited upon that plate. It is
essential to stop this leakage if there be any, otherwise the condensed steam
measured during the consumption test will be increased to the extent of the
leakage. A slight leakage in a large condenser will obviously not affect the
results to any serious extent. The safest course to adopt when a leak is
discovered and it is found inopportune to effect immediate repair is to
measure the actual volume of leakage over a specified period, and the
quantity then being known it can be subtracted from the volume of the
condensed steam at the end of the consumption test.
It is equally essential that no leakage shall occur between the bottom
tube-plate P and the tube ends. The soundness of the tube joints, and the
joint at the periphery of the tube-plate can be tested by well covering the
plate with water, the water chamber W and cooling chamber having been
previously emptied, and observing the under side of the plate. It must be
admitted that the practice of measuring the extent of a water leak over a
period, and afterward with this knowledge adjusting the obtained quantities,
is not always satisfactory. On no account should any test be made with
considerable water leakage inside the condenser. The above method,
however, is perhaps the most reliable to be followed, if during its conduct

the conditions of temperature in the condenser are made as near to the
normal test temperature as possible. There are many condensers using salt
water in their tubes, and in these cases it would seem natural to turn to some
analytical method of detecting the amount of saline and foreign matter
leaking into the condensed steam. Unless, however, only approximate
results are required, such methods are not advocated. There are many
reasons why they cannot be relied upon for accurate results, among these
being the variation in the percentage of saline matter in the sea-water, the
varying temperature of the condenser tubes through which the water flows,
and the uncertainty of such analysis, especially where the percentage
leakage of pure saline matter is comparatively small.

T h e V ac uu m T e s t
Having convinced himself of the satisfactory conduct of the condenser
under the foregoing simple preparatory water tests, the tester may safely
pass to considerations of vacuum. There exists a good old-fashioned
method of discovering the points of leakage in a vacuum chamber, namely,
that of applying the flame of a candle to all seams and other vulnerable
spots, which in the location of big leaks is extremely valuable. Assuming
that the turbine joints and glands have been found capable of preventing
any inleak of air, with only a small absolute pressure of steam or air inside
it, and, further, an extremely important condition, with the turbine casing at
high and low temperatures, separately, a vacuum test can be conducted on
the condenser alone.
This test consists of three operations. In the first place a high vacuum is
obtained by means of the air pump, upon the attainment of which
communication with everything else is closed, and results noted. The
second operation consists in repeating the above with the water circulating
through the condenser tubes, the results in this case also being carefully
tabulated. Before conducting the third test, the condensers must be
thoroughly warmed throughout, by running the turbine for a short time if

necessary, and after closing communication with everything, allowing the
vacuum to slowly fall.
A careful consideration and comparison of the foregoing tests will reveal
the capabilities of the condenser in the aspect in which it is being
considered, and will suggest where necessary the desirable steps to be
taken.

VI. TESTING A STEAM TURBINE [4]
[4] Contributed to Power by Thomas Franklin.

S p e ci a l A u x i l i a ry P l a nt f or C ons ump t i o n
Test
There are one or two points of importance in the conduct of a test on a
turbine and these will be briefly touched upon. Fig. 70 illustrates the
general arrangement of the special auxiliary plant necessary for carrying
through a consumption test, when the turbine exhaust passes through a
surface condenser. The condensed steam, after leaving the condenser,
passes along the pipe A to the pump, and is then forced along the pipe B
(leading under ordinary circumstances to the hot-well), through the main
water valve C directly to the measuring tanks. To enter these the water has
to pass through the valves D and E, while the valves F and G are for
quickly emptying the tanks when necessary, being of a larger bore than the
inlet valves. The inlet pipes H I are placed directly above the outlet valves,
and thus, when required, before any measurements are taken, the water can
flow directly through the outlet valves, the pipes terminating only a short
distance above them, away to an auxiliary tank or directly to the hot-well.
Levers K and L fulcrumed at J and J are connected to the valve spindles by
auxiliary levers. The valve arrangement is such that by pulling down the
lever K the inlet valve D is opened and the inlet valve E is closed. Again, by
pulling down the lever L the outlet valve F is closed, while the outlet valve
G is also simultaneously closed.

FIG. 70

During a consumption test the valves are operated in the following
manner: The lever K is pulled down, which opens the inlet valve to the first
tank and closes that to the second. The bottom lever L, however, is lifted,
which for the time being opens the outlet valve F, and incidentally opens
the valve G; the latter valve can; however, for the moment be neglected.
When the turbine is started, and the condensed steam begins to accumulate
in the condenser, the water is pumped along the pipes and, both the inlet
and outlet valves on the first tank being open, passes through, without any
being deposited in the tank, to the drain. This may be continued until all
conditions are right for a consumption test and, the time being carefully
noted, lever L is quickly pulled down and the valves F and G closed. The
first tank now gradually fills, and after a definite period, say fifteen
minutes, the lever K is pushed up, thus diverting the flow into the second
tank. While the latter is filling, the water in the first tank is measured, and
the tank emptied by a large sluice valve, not shown.

The operation of alternately filling, measuring, and emptying the two
measuring tanks is thus carried on until the predetermined time of duration
of test has expired, when the total water as measured in the tanks, and
representing the amount of steam condensed during that time, is easily
found by adding together the quantities given at each individual
measurement.
All that are necessary to insure successful results from a plant similar to
this are care and accuracy in its operation and construction. Undoubtedly in
most cases it is preferable to weigh the condensed steam instead of
measuring the volume passed, and from that to calculate the weight. If
dependence is being placed upon the volumetric method, it is advisable to
lengthen the duration of the test considerably, and if possible to measure the
feed-water evaporated at the same time. Such a course, however, would
necessitate little change, and none of a radical nature, from the arrangement
described. Where, however, the measuring method is adopted, the all-
important feature, requiring on the tester's part careful personal
investigation, is the graduation of the tanks. It facilitates this operation very
considerably when the receptacles are graduated upon a weight scale. That
is to say, whether or not a vertical scale showing the actual hight of water
be placed inside the tank, it is advisable to have a separate scale indicating
at once to the attendant the actual contents, by weight, of the tank at any
time. It is the tester's duty to himself to check the graduation of this latter
scale by weighing the water with which he performs the operation of
checking.

Apart from the foregoing, there is little to be said about the measuring
apparatus. As has been stated, accuracy of result depends in this connection,
as in all others, upon careful supervision and sound and accurate
construction, and this the tester can only positively insure by exhaustive
inspection in the one case and careful deliberation in the conduct of the
other.
It will be readily understood that the procedure—and this implies some
limitations—of a test is to an extent controlled by the conditions, or

particular environment of the moment. This is strictly true, and as a
consequence it is often impossible, in a maker's works, for example, to
obtain every condition, coinciding with those specified, which are to be had
on the site of final operation only. For this reason it would appear best to
reserve the final and crucial test of a machine, which test usually in the
operating sense restricts a prime mover in certain directions with regard to
its auxiliary plant, etc., until the machine has been finally erected on its site.
Obviously, unless a machine had become more or less standardized, a
preliminary consumption test would be necessary, but once this primary
qualification respecting consumption had been satisfactorily settled, there
appears to be no reason why exhaustive tests in other directions should not
all be carried out upon the site, where the conditions for them are so much
more favorable.
When the steam consumption of a steam turbine is so much higher than
the guaranteed quantity, it usually takes little less than a reconstruction to
put things right. The minor qualifications of a machine, however, which can
be examined into and tested with greater ease, and usually at considerably
less expense, upon the site, and consequently under specified conditions,
may be advantageously left over until that site is reached, where it is
obvious that any shortcomings and general deficiency in performance will
be more quickly detected and diagnosed.

T e s t L o a d s f r o m t he T e s t e r ' s V i e w - p o i n t
Before proceeding to describe the points of actual interest in the
consumption test, a few considerations respecting test loads will be dealt
with from the tester's point of view. Here again we often find ourselves
restricted, to an extent, by the surrounding conditions. The very first
considerations, when undertaking to carry out a consumption test, should be
devoted to obtaining the steadiest possible lead. It may be, and is in many
cases, that circumstances are such as to allow a steady electrical load to be
obtained at almost any time. On the other hand an electrical load of any

description is sometimes not procurable at all, without the installation of a
special plant for the purpose. In such cases a mechanical friction load, as,
for example, that obtained by the water brake, is sometimes available, or
can easily be procured. Whereas, however, this type of load may be
satisfactory for small machines, it is usually quite impossible for use with
large units, of, say, 5000 kilowatts and upward. It is seldom, however, that
turbines are made in large sizes for directly driving anything but electrical
plants, although there is every possibility of direct mechanical driving
between large steam turbines and plants of various descriptions, shortly
coming into vogue, so that usually there exist some facilities for obtaining
an electrical load at both the maker's works and upon the site of operation.
One consideration of importance is worth inquiring into, and this has
relation to the largest turbo-generators supplied for power-station and like
purposes. Obviously, the testing of, say, a 7000-kilowatt alternator by any
standard electrical-testing method must entail considerable expense, if such
a test is to be carried out in the maker's works. Nor would this expense be
materially decreased by transferring the operations to the power-station, and
there erecting the necessary electrical plant for obtaining a water load, or
any other installation of sufficient capacity to carry the required load
according to the rated full capacity of the machine.

Assuming, then, that there exist no permanent facilities at either end,
namely the maker's works and the power station, for adequately procuring a
steady electrical-testing load of sufficient capacity, there still remains, in
this instance, an alternative source of power which is usually sufficiently
elastic to serve all purposes, and this is of course the total variable load
procurable from the station bus-bars. It is conceivable that one out of a
number of machines running in parallel might carry a perfectly steady load,
the latter being a fraction of a total varying quantity, leaving the remaining
machines to receive and deal with all fluctuations which might occur. Even
in the event of there being only two machines, it is possible to maintain the
load on one of them comparatively steady, though the percentage variation
in load on either side of the normal would in the latter case be greater than
in the previous one. This is accomplished by governor regulation after the

machines have been paralleled. For example, assuming three turbo-
alternators of similar make and capacity to be running in parallel, each
machine carrying exactly one-third of the total distributed load, it is fair to
regard the governor condition, allowing for slight mechanical disparities of
construction, of all three machines as being similar; and even in the case of
three machines of different capacity and construction, the governor
conditions when the machines are paralleled are more or less relatively and
permanently fixed in relation to one another. In other words, while the
variation in load on each machine is the same, the relative variation in the
governor condition must be constant.

By a previously mentioned system of governor regulation, however, it is
possible, considering again for a moment the case of three machines in
parallel, by decreasing the sensitiveness of one governor only, to
accommodate nearly all the total variation in load by means of the two
remaining machines, the unresponsiveness of the one governor to change in
speed maintaining the load on that machine fairly constant. By this method,
at any rate, the variation in load on any one machine can be minimized
down to, say, 3 per cent, either side of the normal full load.
There is another and more positive method by which a perfectly steady
load can be maintained upon one machine of several running in parallel.
This may be carried out as follows: Suppose, in a station having a total
capacity of 20,000 kilowatts, there are three machines, two of 6000
kilowatts each, and one of 8000 kilowatts, and it is desired to carry out a
steady full-load test upon one of the 6000 kilowatts units. Assuming that the
test is to be of six hours' duration, and that the conditions of load
fluctuations upon the station are well known, the first step to take is to
select a period for the test during which the total load upon all machines is
not likely to fall below, say, 8000 kilowatts. The tension upon the governor
spring of the turbine to be tested must then be adjusted so that the machine
on each peak load is taxed to its utmost normal capacity; and even when the
station load falls to its minimum, the load from the particular machine shall
not be released sufficiently to allow it to fall below 6000 kilowatts. Under
these conditions, then, it may be assumed that although the load on the test

machine will vary, it cannot fall below 6000 kilowatts. Therefore, all that
remains to be done to insure a perfectly steady load equal to the normal full
load of the machine, or 6000 kilowatts, is to fix the main throttle or
governing valve in such a position that the steam passing through at
constant pressure is just capable of sustaining full speed under the load
required. When this method is adopted, it is desirable to fix a simple hight-
adjusting and locking mechanism to the governing-valve spindle. The load
as read on the indicating wattmeter can then be very accurately varied until
correct, and farther varied, if necessary, should any change occur in the
general conditions which might either directly or indirectly bring about a
change of load.

P r e pa r i n g t he T urbi ne f or T e s t i n g
All preliminary labors connected with a test being satisfactorily disposed of,
it only remains to place the turbines under the required conditions, and to
then proceed with the test. For the benefit of those inexperienced in the
operation of large turbines, we will assume that such a machine is about to
be started for the purpose outlined.

It is always advisable to make a strict practice of getting all the auxiliary
plant under way before starting up the turbine. In handling a turbine plant
the several operations might be carried through in the following order:
(1) Circulating oil through all bearings and oil chambers.[5]
(2) Starting of condenser circulating-water pumps, and continuous
circulation of circulating water through the tubes of condenser.
(3) Starting of pump delivering condensed steam from the condenser hot-
well to weighing tanks.
(4) Starting of air pump, vacuum being raised as high as possible within
condenser.

(5) Sealing of turbine glands, whether of liquid or steam type, no
adjustment of the quantity of sealing fluid being necessary, however, at this
point.
(6) Adjustment of valves on and leading to the water-weighing tanks.
(7) Opening of main exhaust valve or valves between turbine and
condenser.
(8) Starting up of turbine and slowly running to speed.
(9) Application of load, and adjustment of gland-sealing steam.
[5] In a self-contained system, where the oil pump is usually driven from the turbine
spindle, this would of course be impossible. In the gravity and allied systems, however, it
should always be the first operation performed. The tests for oil consumption, described
previously, having been carried out, it is assumed that suitable means have been adopted
to restrict the total oil flow through the bearings to a minimum quantity.

The running to speed of large turbo-alternators requires considerable
care, and should always be done slowly; that is to say the rate of
acceleration should be slow. It is well known that the vibration of a heavy
unit is accompanied by a synchronous or non-synchronous vibration of the
foundation upon which it rests. The nearest approach to perfect
synchronism between unit and foundation is obtained by a gradual rise in
speed. A machine run up to speed too quickly might, after passing the
critical speed, settle down with little visible vibration, but at a later time,
even hours after, suddenly begin vibrating violently from no apparent cause.
The chances of this occurring are minimized by slow and careful running to
speed.
Whether the machine being tested is one of a number running in parallel,
or a single unit running on a steady water load, the latter should in all cases
be thrown on gradually until full load is reached. A preliminary run of two
or three hours—whenever possible—should then be made, during which
ample opportunity is afforded for regulating the conditions in accordance
with test requirements. The tester will do well during the last hour of this
trial run to station his recorders at their several posts and, for a short time at
least, to have a complete set of readings taken at the correct test intervals.

This more particularly applies to the electrical water, superheat and vacuum
readings. In the case of a turbo-alternator the steadiness obtainable in the
electrical load may determine the frequency of readings taken, both
electrical and otherwise. On a perfectly steady water-tank load, for
example, it may be sufficiently adequate to read all wattmeters, voltmeters,
and ammeters from standard instruments at from one- to two-minute
intervals. Readings at half-minute intervals, however, should be taken with
a varying load, even when the variation is only slight.
The water-measurement readings may of course be taken at any suitable
intervals, the time being to an extent determined by the size of the
measuring tanks or the capacity of the weighing machine or machines.
When designing the measuring apparatus, the object should be to minimize,
within economical and practical range, the total number of weighings or
measurements necessary. Consequently, no strict time of interval between
individual weighings or measurements can be given in this case. It may be
said, however, that it is not desirable to take these at anything less than five-
minute intervals. Under ordinary circumstances a three- to five-minute
interval is sufficient in the case of all steam-pressure, vacuum—including
mercurial columns and barometer—superheat and temperature readings.

G l a n d a nd H ot -W e l l R e gul at i on
There are two highly important features requiring more or less constant
attention throughout a test, namely the gland and hot-well regulation. For
the present purpose we may assume that the glands are supplied with either
steam or water for sealing them. All steam supplied to the turbine obviously
goes to swell the hot-well contents, and to thus increase the total steam
consumption. The ordinary steam gland is in reality a pressure gland. At
both ends of the turbine casing is an annular chamber, surrounding the
turbine spindle at the point where it projects through the casing. A number
of brass rings on either side of this chamber encircle the spindle, with only a
very fine running clearance between the latter and themselves. Steam enters

the gland chamber at a slight pressure, and, when a vacuum exists inside the
turbine casing, tends to flow inward. The pressure, however, inside the
gland is increased until it exceeds that of the atmosphere outside, and by
maintaining it at this pressure it is obvious that no air can possibly enter the
turbine through the glands, to destroy the vacuum. The above principle
must be borne in mind during a test upon a turbine having steam-fed glands.
Perhaps the best course to follow—in view of the economy of gland steam
consumption necessary—is as follows:

During the preliminary non-test run, full steam is turned into both glands
while the vacuum is being raised, and maintained until full load has been on
the turbine for some little time. The vacuum will by this time have probably
reached its maximum, and perhaps fallen to a point slightly lower, at which
hight it may be expected to remain, other conditions also remaining
constant. The gland steam must now be gradually turned off until the
amount of steam vapor issuing from the glands is almost imperceptible.
This should not lower the vacuum in the slightest degree. By gradual
degrees the gland steam can be still farther cut down, until no steam vapor
at all can be discerned issuing from the gland boxes. This reduction should
be continued until a point is reached at which the vacuum is affected, when
it must be stopped and the amount of steam flowing to the gland again
increased very slightly, just enough to bring the vacuum again to its original
hight. The steam now passing into the glands is the minimum required
under the conditions, and should be maintained as nearly constant as
possible throughout the test. Practically all steam entering the glands is
drawn into the turbine, and thence to the condenser, and under the
circumstances it may be assumed the increase in steam consumption arising
from this source is also a minimum.
There is one mechanical feature which has an important bearing upon
the foregoing question, and which it is one of the tester's duties to
investigate. This is illustrated in Fig. 71, which shows a turbine spindle
projecting through the casing. The gland box is let into the casing as shown.
Brass rings A calked into the gland box encircle the shaft on either side of
the annular steam space S. As the clearance between the turbine spindle and

the rings A is in a measure instrumental in determining the amount of steam
required to maintain a required pressure inside the chamber, it is obvious
that this clearance should be minimum. An unnecessarily large clearance
means a proportionally large increase in gland steam consumption and vice
versa.

FIG. 71

When the turbine glands are sealed with water, all water leakage which
takes place into the turbine, and ultimately to the condenser hot-well, must
be measured and subtracted from the hot-well contents at the end of a test.

The foregoing remarks would not apply to those cases in which the
gland supply is drawn from and returned to the hot-well, or a pipe leading
from the hot-well. Then no correction would be necessary, as all water used
for gland purposes might be assumed as being taken from the measuring
tanks and returned again in time for same or next weighing or measurement.

G e n e r al C on s i de r at i ons
There are a few principal elementary points which it is necessary always to
keep in mind during the conduct of a test. Among these are the effects of
variation in vacuum, superheat, initial steam pressure, and, as already
indicated, in load. There exist many rules for determining the corrections
necessitated by this variation. For example, it is often assumed that 9
degrees Fahrenheit, excess or otherwise, above or below that specified,
represents an increase or reduction in efficiency of about 1 per cent. It is
probable that the percentage increase or decrease in steam consumption, in
the case of superheat, can be more reliably calculated than in other cases,
as, for example, vacuum; but the increase cannot be said to be due solely to
the variation in superheat. In other words, the individuality of the particular
turbine being tested always contributes something, however small this
something may be, to the results obtained.
These remarks are particularly applicable where vacuum is concerned.
Here again rules exist, one of these being that every additional inch of
vacuum increases the economy of the turbine by something slightly under
half a pound of steam per kilowatt-hour. But a moment's consideration
convinces one of the utter unreliability of such rules for general application.
It is, for instance, well known that many machines, when under test, have
demonstrated that the total increase in the water rate is very far from
constant. A machine tested, for example, gave approximately the following
results, the object of the test being to discover the total increase in the water
rate per inch decrease in vacuum:
From 27 inches to 26 inches, 4.5 per cent.

From 26.2 inches to 24.5 inches, 2.5 per cent.

This illustrates to what an extent the ratio of increase can vary, and it
must be borne in mind that it is very probable that the variation is different
in different types and sizes of machines.

There can exist, therefore, no empirical rules of a reliable nature upon
which the tester can base his deductions. The only way calculated to give
satisfaction is to conduct a series of preliminary tests upon the turbine
undergoing observation, and from these to deduce all information of the
nature required, which can be permanently recorded in a set of curves for
reference during the final official tests.
In conclusion, it must be admitted that many published tests outlining
the performances of certain makes of turbine are unreliable. To determine
honestly the capabilities of any machine in the direction of steam economy
is an operation requiring time, and unbiased and accurate supervision. By
means of such assets as "floating quantities," short tests during
exceptionally favorable conditions, and disregard of the vital necessity of
running a test under the proper specified conditions, it is comparatively
easy to obtain results apparently highly satisfactory, but which under other
conditions might be just the reverse. These considerations are, however,
unworthy of the tester proper.

VII. AUXILIARIES FOR STEAM
TURBINES [6]
[6] Contributed to Power by Thomas Franklin.

T h e J e t C onde n s e r
The jet condenser illustrated in Fig. 72 is singularly well adapted for the
turbine installation. As the type has not been so widely adopted as the more
common forms of jet condenser and the surface types, it may prove of
interest to describe briefly its general construction and a few of its special
features in relation to tests.

FIG. 72

Referring to the figure, C is the main condenser body. Exhaust steam
enters at the left-hand side through the pipe E, condensing water issuing
through the pipe D at the opposite side. Passing through the short conical
pipe P, the condensing water enters the cylindrical chamber W and falls
directly upon the spraying cone S. The hight of this spraying cone is
determined by the tension upon the spring T, below the piston R, the latter
being connected to the cone by a spindle L. An increase of the water

pressure inside the chamber W will thus compress the spring, and the
spraying cone being consequently lowered increases the aperture between it
and the sloping lower wall of the chamber W, allowing a greater volume of
water to be sprayed. The piston R incidentally prevents water entering the
top vapor chamber V. From the foregoing it can be seen that this condenser
is of the contra-flow type, the entering steam coming immediately into
contact with the sprayed water. The perforated diaphragm plate F allows the
vapor to rise into the chamber V, from which it is drawn through the pipe A
to the air pump. A relief valve U prevents an excessive accumulation of
pressure in the vapor chamber, this valve being obviously of delicate
construction, capable of opening upon a very slight increase of the internal
pressure over that of the atmosphere. Condensed steam and circulating
water are together carried down the pipe B to the well Z, from which a
portion may be carried off as feed water, and the remainder cooled and
passed through the condenser again. Under any circumstances, whether the
air pump is working or not, a certain percentage of the vapor in the
condenser is always carried down the pipe B, and this action alone creates a
partial vacuum, thus rendering the work of the air pump easier. As a matter
of fact, a fairly high vacuum can be maintained with the air pump closed
down, and only the indirect pumping action of the falling water operating to
rarify the contents of the condenser body. It is customary to place the
condenser forty or more feet above the circulating-water pump, the latter
usually being a few feet below the turbine.

F e at u r e s D e man di ng A t t e nt i on
When operating a condenser of this type, the most important features
requiring preliminary inspection and regulation while running are:
(a) Circulating-water regulation.
(b) Freedom of all mechanical parts of spraying mechanism.
(c) Relief-valve regulation.

(d) Water-cooling arrangements.
The tester will, however, devote his attention to a practical survey of the
condenser and its auxiliaries, before running operations commence.

A preliminary vacuum test ought to be conducted upon the condenser
body, and the exhaust piping between the condenser and turbine. To
accomplish this the circulating-water pipe D can be filled with water to the
condenser level. The relief valve should also be water-sealed. Any existing
leakage can thus be located and stopped.

Having made the condenser as tight as possible within practical limits,
vacuum might be again raised and, with the same parts sealed, allowed to
fall slowly for, say, ten minutes. A similar test over an equal period may
then be conducted with the relief valve not water-sealed. A comparison of
the times taken for an equal fall of vacuum in inches, under the different
conditions, during the above two tests, will reveal the extent of the leakage
taking place through the relief valve. It seems superfluous to add that the
fall of vacuum in both the foregoing tests must not be accelerated in any
way, but must be a result simply of the slight inevitable leakage which is to
be found in every system.
On a comparatively steady load, and with consequently only small
fluctuation in the volume of steam to be condensed, the conditions are most
favorable for regulating the amount of circulating water necessary.
Naturally, an excess of water above the required minimum will not affect
the pressure conditions inside the condenser. It does, however, increase the
quantity of water to be handled from the hot-well, and incidentally lowers
the temperature there, which, whether the feed-water pass through
economizers or otherwise, is not advisable from an economical standpoint.
Thus there is an economical minimum of circulating water to be aimed at,
and, as previously stated, it can best be arrived at by running the turbine
under normal load and adjusting the flow of the circulating water by
regulating the main valve and the tension upon the spring T. Under
abnormal conditions, the breakdown of an air pump, or the sudden
springing of a bad leak, for instance, the amount of circulating water can be

increased by a farther opening of the main valve if necessary, and a
relaxation of the spring tension by hand; or, the spring tension might be
automatically changed immediately upon the vacuum falling.
The absolute freedom of all moving parts of the spraying mechanism
should be one of the tester's first assurances. To facilitate this, it is
customary to construct the parts, with the exception of the springs, of brass
or some other non-corrosive metal. The spraying cone must be thoroughly
clean in every channel, to insure a well-distributed stream of water. Nor is it
less important that careful attention be given to the setting and operation of
the relief valve, as will be seen later. The obvious object of such a valve is
to prevent the internal condenser pressure ever being maintained much
higher than the atmospheric pressure. A number of carefully designed
rubber flap valves, or one large one, have been found to act successfully for
this purpose, although a balanced valve of more substantial construction
would appear to be more desirable.

I mp o rta n c e of R e l i e f V a lv e s
The question of relief valves in turbine installations is an important one, and
it seems desirable at this point to draw attention to another necessary relief
valve and its function, namely the turbine atmospheric valve. As generally
understood, this is placed between the turbine and condenser, and, should
the pressure in the latter, owing to any cause, rise above that of the
atmosphere, it opens automatically and allows the exhaust steam to flow
through it into the atmosphere, or into another condenser.

A general diagrammatic arrangement of a steam turbine, condenser, and
exhaust piping is shown in Fig. 73. Connected to the exhaust pipe B, near to
the condenser, is the automatic atmospheric valve D, from which leads the
exhaust piping E to the atmosphere. The turbine relief valve is shown at F,
and the condenser relief valve at G. The main exhaust valve between
turbine and condenser is seen at H. We have here three separate relief
valves: one, F, to prevent excessive pressure in the turbine: the second, D,

an atmospheric valve opening a path to the air, and, in addition to
preventing excessive pressure accumulating, also helping to keep the
temperature of the condenser body and tubes low; the third, the condenser
relief valve G, which in itself ought to be capable of exhausting all steam
from the turbine, should occasion demand it.

FIG. 73
Assuming a plant of this description to be operating favorably, the
conditions would of necessity be as follows: The valves F, D, and G, all
closed; the valve H open. Suppose that, owing to sudden loss of circulating
water, the vacuum fell to zero. The condenser would at once fill with steam,
a slight pressure would be set up, and whichever of the three valves
happened to be set to blow off at the lowest pressure would do so. Now it is
desirable that the first valve to open under such circumstances should be the
atmospheric valve D. This being so, the condenser would remain full of
steam at atmospheric pressure until the attendant had had time to close the
main hand-or motor-operated exhaust valve H, which he would naturally do
before attempting to regain the circulation of the condensing water. Again,

assume the installation to be running under the initial conditions, with the
atmospheric valve D and all remaining valves except H closed.

Suppose the vacuum again fell to zero from a similar cause, and, further,
suppose the atmospheric valve D failed to operate automatically. The only
valves now capable of passing the exhaust steam are the turbine and
condenser relief valves F and G. Inasmuch as the pressures at exhaust in the
turbine proper, on varying load, vary over a considerably greater range than
the small fairly constant absolute pressures inside the condenser, it is
obviously necessary to allow for this factor in the respective setting of these
two relief valves. In other words, the obvious deduction is to set the turbine
relief valve to blow off at a higher pressure than the condenser relief valve,
even when considering the question with respect to condensing conditions
only. In this second hypothetical case, then, with a closed and disabled
atmospheric valve, the exhaust must take place through the condenser, until
the turbine can be shut down, or the circulating water regained without the
former course being found necessary.

There is one other remote case which may be assumed, namely, the
simultaneous refusal of both atmospheric and condenser relief valves to
open, upon the vacuum inside the condenser being entirely lost. The
exhaust would then be blown through the turbine relief valve F, until the
plant could be closed down.

Although the conditions just cited are highly improbable in actual
practice, it can at once be seen that to insure the safety of the condenser,
absolutely, the turbine relief valve must be set to open at a comparatively
low pressure, say 40 pounds by gage, or thereabouts. To set it much lower
than this would create a possibility of its leaking when the turbine was
making a non-condensing run, and when the pressure at the turbine exhaust
end is often above that of the atmosphere. From every point of view,
therefore, it is advisable to make a minute examination of all relief valves in
a system, and before a test to insure that these valves are all set to open at
their correct relative pressures.

It must be admitted that the practice of placing a large relief valve upon
a condenser in addition to the atmospheric exhausting valve is by no means
common. The latter valve, where surface condensing is adopted, is often
thought sufficient, working in conjunction with a quickly operated main
exhaust valve. Similarly, with a barometric condenser as that illustrated in
Fig. 72, the atmospheric exhaust valve D (seen in Fig. 73) is sometimes
dispensed with. This course is, however, objectionable, for upon a loss of
vacuum in the turbine, all exhaust steam must pass through the condenser
body, or the entire plant be closed down until the vacuum is regained. The
simple construction of the barometric condenser, however, is in such an
event much to its advantage, and the passage of the hot steam right through
it is not likely to seriously warp or strain any of its parts, as might probably
happen in the case of a surface condenser.
The question of the advisability of thus adding to a plant can only be
fairly decided when all conditions, operating and otherwise, are fully
known. For example, if we assume a large turbine to be operating on a
greatly varying load, and exhausting into a condenser, as that in Fig. 72,
and, further, having an adequate stand-by to back it up, one's obvious
recommendation would be to equip the installation with both a condenser
relief valve and an atmospheric valve, in addition, of course, to the main
exhaust valve, which is always placed between the atmospheric valve and
condenser. There are still other considerations, such as water supply,
condition of circulating water, style of pump, etc., which must all
necessarily have an obvious bearing upon the settlement of this question; so
that generalization is somewhat out of place, the final design in all cases
depending solely upon general principles and local conditions.

O t he r N e ce s s ary F e at ur e s of a T e s t
In connection with the condenser, of any type, and its auxiliaries, there
remain a few necessary examinations and operations to be conducted, if it is
desired to obtain the very best results during the test. It will be sufficient to

just outline them, the method of procedure being well known, and the
requirement of any strict routine being unnecessary. These include:
(1) A thorough examination of the air-pump, and, if possible, an equally
careful examination of diagrams taken from it when running on full load.
Also careful examination of the piping, and of any other connections
between the air pump and condenser, or other auxiliaries. It will be well in
this examination to note the general "lay" of the air pipes, length, hight to
which they rise above condenser and air pump, facilities for drainage, etc.,
as this information may prove valuable in determining the course necessary
to rectify deficiencies which may later be found to exist.
(2) In a surface condenser, inspection of the pumps delivering condensed
steam to the measuring tanks or hot-well; inspection of piping between the
condenser and the pump, and also between the pump and measuring tanks.
If these pumps are of the centrifugal type it is essential to insure, for the
purposes of a steam-consumption test, as much regularity of delivery as
possible.
(3) In the case of a consumption test upon a turbine exhausting into a
barometric condenser, and where the steam consumed is being measured by
the evaporation in the boiler over the test period, time must be devoted to
the feed-pipes between the feed-water measuring meter or tank and the
boilers. Under conditions similar to those operating in a plant such as that
shown in Fig. 72, the necessary boiler feed might be drawn from the hot-
well, the remainder of the hot-well contents probably being pumped
through water coolers, or towers, for circulating through the condenser.
With the very best system, it is possible for a slight quantity of oil to leak
into the exhaust steam, and thence to the hot-well. In its passage, say along
wooden conduits, to the measuring tank or meter, this water would probably
pass through a number of filters. The efficiency of these must be thoroughly
insured. It is unusual, in those cases where a simple turbine steam-
consumption test is being carried out, and not an efficiency test of a
complete plant, to pass the measured feed-water through economizers.
Should the latter course, owing to special conditions, become necessary, a
careful examination of all economizer pipes would be necessary.

(4) The very careful examination of all thermometer pockets, steam- and
temperature-gage holes, etc., as to cleanliness, non-accumulation of scale,
etc.

S p e ci a l A uxi l i ar i e s N e ce s s a ry
Having outlined the points of interest and importance in connection with the
more permanent features of a plant, we arrive at the preparation and fitting
of those special auxiliaries necessary to carry on the test.

FIG. 74
It is customary, when carrying out a first test, upon both prime mover
and auxiliaries, to place every important stage in the expansion in
communication with a gage, so that the various pressures may be recorded
and later compared with the figures of actual requirement. To do this, in the
case of the turbine, it is necessary to bore holes in the cover leading to the
various expansion chambers, and into each of these holes to screw a short

length of steam pipe, having preferably a loop in its length, to the other end
of which the gage is attached. Fig. 74 illustrates, diagrammatically, a
complete turbine installation, and shows the various points along the course
taken by the steam at which it is desirable to place pressure gages. The
figure does not show the high-pressure steam pipe, nor any of the turbine
valves. With regard to these, it will be desirable to place a steam gage in the
pipe, immediately before the main stop-valve, and another immediately
after it. Any fall of pressure between the two sides of the valve can thus be
detected. To illustrate this clearly, Fig. 75 is given, showing the valves of a
turbine, and the position of the gages connected to them. The two gages E
and F on either side of the main stop-valve A are also shown. The steam
after passing through the valve, which, in the case of small turbines, is
hand-operated, goes in turn through the automatic stop-valve B, the
function of which is to automatically shut steam off should the turbine
attain a predetermined speed above the normal, the steam strainer C, and
finally through the governing valve D into the turbine. As shown, gages G
and H are also fitted on either side of the strainer, and these, in conjunction
with gages E and F, will enable any fall in pressure between the first two
valves and the governing valve to be found. Up to the governing-valve inlet
no throttling of the steam ought to take place under normal conditions, i.e.,
with all valves open, and consequently any fall in pressure between the
steam inlet and this point must be the result of internal wire-drawing. By
placing the gages as shown, the extent to which this wire-drawing affects
the pressures obtainable can be discovered.

FIG. 75

On varying and even on normal and steady full load, the steam is more
or less reduced in pressure after passing through the governing valve D; a
gage I must consequently be placed between the valve, preferably on the
valve itself, and the turbine. Returning to Fig. 74, the gages shown are A, B,
C, D, and E, connected to the first, second, third, fourth, and fifth
expansions; also F in the turbine and exhaust space, where there are no
blades, G in the exhaust pipe immediately before the main exhaust valve E
(see Fig. 73), and H connected to the condenser. On condensing full load it
is probable that A, B, and C will all register pressures above the atmosphere,
while gages D, E, F, and G will register pressures below the atmosphere,
being for this purpose vacuum gages. On the other hand, with a varying
load, and consequently varying initial pressures, one or two of the gages
may register pressure at one moment and vacuum at another. It will
therefore be necessary to place at these points compound gages capable of
registering both pressure and vacuum. With the pressures in the various
stages constantly varying, however, a gage is not by any means the most
reliable instrument for recording such variations. The constant swinging of
the finger not only renders accurate reading at any particular moment both
difficult and, to an extent, unreliable, but, in addition, the accompanying
sudden changes of condition, both of temperature and pressure, occurring
inside the gage tube, in a comparatively short time permanently warp this
part, and thus altogether destroy the accuracy of the gage. It is well known
that even with the best steel-tube gages, registering comparatively steady
pressures, this warping of the tube inevitably takes place. The quicker
deterioration of such gage tubes, when the gage is registering quickly
changing pressures, can therefore readily be conceived, and for this reason
alone it is desirable to have all gages, whatever the conditions under which
they work, carefully tested and adjusted at short intervals. If it is desired to
obtain reliable registration of the several pressures in the different
expansions of a turbine running on a varying load, it would therefore seem
advisable to obtain these by some type of external spring gage (an ordinary
indicator has been found to serve well for this purpose) which the sudden
internal variations in pressure and temperature cannot deleteriously affect.

In view of the great importance he must attach to his gage readings, the
tester would do well to test and calibrate and adjust where necessary all the
gages he intends using during a test. This he can do with a standard gage-
testing outfit. By this means only can he have full confidence in the
accuracy of his results.

In like manner it is his duty personally to supervise the connecting and
arrangement of the gages, and the preliminary testing for leakage which can
be carried out simultaneously with the vacuum test made upon the turbine
casing.

W he r e T h e r mome t e r s a re R e q ui r e d
Equally important with the foregoing is the necessity of calibrating and
testing of all thermometers used during a test. Where possible it is advisable
to place new thermometers which have been previously tested at all points
of high temperature. Briefly running them over, the points at which it is
necessary to place thermometers in the entire system of the steam and
condensing plant are as follows:
(1) A thermometer in the steam pipe on the boiler, where the pipe leaves the
superheater.
(2) In the steam pipe immediately in front of the main stop-valve, near point
E in Fig. 75.
(3) In the main governing valve body (see I, Fig. 75) on the inlet side.
(4) In the main governing valve body on the turbine side, which will
register temperatures of steam after it has passed through the valve.
(5) In the steam-turbine high-pressure chamber, giving the temperature of
the steam before it has passed through any blades.
(6) In the exhaust chamber, giving the temperature of steam on leaving the
last row of blades.
(7) In the exhaust pipe near the condenser.

(8) In the condenser body.
(9) In the circulating-water inlet pipe close to the condenser.
(10) In the circulating-water outlet pipe close to the condenser.
(11) In the air-pump suction pipe close to the condenser.
(12) In the air-pump suction pipe close to the air pump.
It is not advisable to place at those vital points, the readings at which
directly or indirectly affect the consumption, two thermometers, say one
ordinary chemical thermometer and one thermometer of the gage type, thus
eliminating the possibility of any doubt which might exist were only one
thermometer placed there.
There is no apparent reason why one should attempt to take a series of
temperature readings during a consumption test on varying load. The
temperatures registered under a steady load test can be obtained with great
reliability, but on a varying load, with constantly changing temperatures at
all points, this is impossible. This is, of course, owing to the natural
sluggishness of the temperature-recording instruments, of whatever class
they belong to, in responding to changes of condition. As a matter of fact,
the possibility of obtaining correctly the entire conditions in a system
running under greatly varying loads is very doubtful indeed, and
consequently great reliance cannot be placed upon figures obtained under
such conditions.
A few simple calculations will reveal to the tester his special
requirements in the direction of measuring tanks, piping, etc., for his steam
consumption test. Thus, assuming the turbine to be tested to be of 3000
kilowatt capacity normal load, with a guaranteed steam consumption of,
say, 14.5 pounds per kilowatt-hour, he calculates the total water rate per
hour, which in this case would be 43,500 pounds, and designs his weighing
or measuring tanks to cope with that amount, allowing, of course, a
marginal tank volume for overload requirements.

VIII. TROUBLES WITH STEAM TURBINE
AUXILIARIES [7]
[7] Contributed to Power by Walter B. Gump.

The case about to be described concerns a steam plant in which there
were seven cross-compound condensing Corliss engines, and two Curtis
steam turbines. The latter were each of 1500-kilowatt capacity, and were
connected to surface condensers, dry-vacuum pumps, centrifugal, hot-well
and circulating pumps, respectively. In the illustration (Fig. 76), the original
lay-out of piping is shown in full lines. Being originally a reciprocating
plant it was difficult to make the allotted space for the turbines suitable for
their proper installation. The trouble which followed was a perfectly natural
result of the failure to meet the requirements of a turbine plant, and the
description herein given is but one example of a great many where the
executive head of a concern insists upon controlling the situation without
regard to engineering advice or common sense.

FIG. 76. TURBINE AUXILIARIES AND PIPING

C i r cu l at i n g P u mp F ai l s to M e e t G ua ra n t e e
Observing the plan view, it will be seen that the condensers for both
turbines receive their supply of cooling water from the same supply pipe;
that is, the pipes, both suction and discharge, leading to No. 1 condenser are
simply branches from No. 2, which was installed first without consideration
for a second unit. When No. 1 was installed there was a row of columns
from the basement floor to the main floor extending in a plane which came
directly in front of the condenser. The column P shown in the plan was so
located as to prevent a direct connection between the centrifugal circulating
pump and the condenser inlet. The centrifugal pump was direct-connected
to a vertical high-speed engine, and the coupling is shown at E in the
elevation.

Every possible plan was contemplated to accommodate the engine and
pump without removing any of the columns, and the arrangement shown
was finally adopted, leaving the column P in its former place by employing
an S-connection from the pump to the condenser. It should be stated that the
pump was purchased under a guarantee to deliver 6000 gallons per minute
under a head of 50 feet, with an impeller velocity of 285 revolutions per
minute. The vertical engine to which the pump was connected proved to be
utterly unfit for running at a speed beyond 225 to 230 revolutions per
minute, and in addition the S-bend would obviously reduce the capacity,
even at the proper speed of the impeller.

Besides these factors there was another feature even more serious. It was
found that when No. 2 unit was operating No. 1 could not get as great a
quantity of circulating water as when No. 2 was shut down. This was
because No. 2 was drawing most of the water, and No. 1 received only that
which No. 2 could not pull from the suction pipe A. This will be clear from
the fact that the suction and discharge pipes for No. 1 were only 16 inches,
while those of No. 2 were 20 inches and 16 inches, respectively. The
condenser for No. 2 had 1000 square feet less cooling surface than No. 1,
which had 6000 square feet and was supplied with cooling water by means
of two centrifugal pumps of smaller capacity than for No. 1 and arranged in
parallel. These were each driven by an electric motor, and were termed
"The Siamese Twins," due to the way in which they were connected.
The load factor of the plant ranged from 0.22 to 0.30, the load being
almost entirely lighting, so that for the winter season the load factor reached
the latter figure. The day load was, therefore, light and not sufficient to give
one turbine more than from one-fourth to one-third its rated capacity. Under
these conditions No. 1 unit was able to operate much more satisfactorily
than when fully loaded, because of the fact that the cooling water was more
effective. This was, of course, all used by No. 1 unit when No. 2 was not
operating. At best, however, it was found that the vacuum could not be
made to exceed 24 inches, and during the peak, with the two turbines
running, the vacuum would often drop to 12 inches. A vacuum of 16 inches
or 18 inches on the peak was considered good.

A n I nve s t i gat i o n
Severe criticism "rained" heavily upon the engineer in charge, and
complaints were made in reference to the high oil consumption. An
investigation on the company's part followed, and the firm which furnished
the centrifugal pump and engine was next in order to receive complaints.
Repeated efforts were made to increase the speed of the vertical engine to
285 revolutions per minute, but such a speed proved detrimental to the
engine, and a lower speed of about 225 revolutions per minute had to be
adopted.
A thorough test on the pump to ascertain its delivery at various speeds
was the next move, and a notched weir, such as is shown in the elevation,
was employed. The test was made on No. 2 cooling tower, not shown in the
sketch, and showed that barely 3000 gallons per minute were being
delivered to the cooling tower. While the firm furnishing the pump was
willing to concede that the pump might not be doing all it should, attention
was called to the fact that there might be some other conditions in
connection with the system which were responsible for the losses. Notable
among these was the hydraulic friction, and when this feature of the case
was presented, the company did not seem at all anxious to investigate the
matter further; obviously on account of facing a possible necessity for new
piping or other apparatus which might cost something.
Approximately 34 feet was the static head of water to be pumped over
No. 2 cooling tower. Pressure gages were connected to the suction,
discharge, and condenser inlet, as shown at G, G' and G'' respectively.
When No. 1 unit was operating alone the gage G showed practically zero,
indicating no vacuum in the suction pipe. Observing the same gage when
No. 2 unit was running, a vacuum as high as 2 pounds was indicated,
showing that No. 2 was drawing more than its share of cooling water from
the main A and hence the circulating pump for No. 1 was fighting for all it
received. Gage G' indicated a pressure of 21 pounds, while G'' indicated
18.5 pounds, showing a difference of 2.5 pounds pressure lost in the S-
bend. This is equivalent to a loss of head of nearly 6 feet, 0.43 pound per

foot head being the constant employed. The total head against which the
pump worked was therefore

G' + G = 21 + 2,
or
23
—— = 53
0.43
feet approximately. Since the static head was 34 feet, the head lost in
friction was evidently
53-34 = 19

feet, or
1900
—— = 36
53

per cent., approximately.

S up p ly o f C ool i ng W at e r L i mi t e d
In addition to this the supply of cooling water was limited, the vacuum
being extremely low at just the time when efficient operation should be had.
The natural result occurred, which was this: As the load on the turbine
increased, the amount of steam issuing into the condenser increased,
beating the circulating water to a temperature which the cooling tower (not
in the best condition) was unable to decrease to any great extent. The
vacuum gradually dropped off, which indicated that the condenser was
being filled with vapor, and in a short time the small centrifugal tail-pump
lost its prime, becoming "vapor bound," and the vacuum further decreased.
The steam which had condensed would not go into the tail-pump because of

the tendency of the dry-pump to maintain a vacuum. When a certain point
was reached the dry-vacuum pump started to draw water in its cylinder, and
the unit had to be shut down immediately.

V a p o r - bo un d P ump s
As the circulating water gradually rose in temperature the circulating pump
also became "vapor bound," so that the unit would be tied up for the rest of
the night, as this pump could not be made to draw hot water. The reason for
this condition may be explained in the following way. When the circulating
pump was operating and there was a suction of 2 pounds indicated at G, the
water was not flowing to the pump of its own accord, but was being pulled
through by force. This water would flow through the pump until a point was
reached when the water became hot enough to be converted into vapor, this
occurring at a point where the pressure was sufficiently reduced to cause the
water to boil. Naturally this point was in the suction pipe and vapor was
thus maintained behind the pump as long as it was operating. In this case
the pump was merely maintaining a partial vacuum, but not drawing water.
After the vacuum was once lost, by reason of the facts given, it could not be
regained, as the circulating water, piping and condenser required a
considerable period of time in which to cool.
Before any radical changes were made it was decided that a man should
crawl in the suction pipe A, and remove such sand, dirt, or any other
obstacles as were believed to cause the friction. After this had been done
and considerable sand had been removed, tests were resumed with
practically the same results as before. The investigation was continued and
the dry-vacuum pumps were overhauled, as they had been damaged by
water in the cylinders, and furthermore needed re-boring. In short, the
auxiliaries were restored to the best condition that could be brought about
by the individual improvement of each piece of apparatus. As this was not
the seat of the trouble, however, the remedy failed to effect a "cure." It was
demonstrated that the steam consumption of the turbines was greatly

increased due to priming of the boilers, as well as condensation in the
turbine casing; hence, the ills above mentioned were aggravated.

C h a nge s i n P i p i ng
After a great deal of argument from the chief engineer, and the firm which
furnished the pump, both making a strong plea for a change in the piping,
the company accepted the inevitable, and the dotted portion shows the
present layout. The elbow M was removed, and a tee put in its place to
which the piping D was connected. The circulating pump was removed to
the position shown, and a direct connection substituted for the S-bend. The
discharge pipe C was carried from No. 1 unit separately, as shown in the
elevation, and terminated at No. 1 cooling tower instead of No. 2, which
shortened the distance about 60 feet, the total length of pipe (one way) from
No. 1 unit being originally 250 feet. In this way the condensing equipment
was made practically separate for each turbine, as it should have been in the
first place.
With the new piping a vacuum of 24 inches on the peak could be
reached. While this is far from an efficient value, yet it is better than the
former figure. The failure to reach a vacuum of 28 inches or better is due
primarily to a lack of cooling water, but an improvement in this regard
could be made by reconstructing the cooling towers, which at present do not
offer the proper amount of cooling surface. The screens used were heavy
galvanized wire of about 3/16-inch mesh, which became coated in a short
time, and must be thoroughly cleaned to permit the water to drop through
them. The supply of cooling water was taken from a 30-inch pipe line
several miles long and fed from a spring. The amount of water varied
considerably and was at times quite insufficient for the load on the plant.
Instead of meeting this condition with the best apparatus possible, a chain
of difficulties were added to it, with the results given.

INDEX
Acceleration, rate of, 147
Adjustment, axial, 65
making, 66
Air-pump, examining, 163
Allis-Chalmers Co. steam turbine, 41
Auxiliaries, 2, 154
special, 165
Auxiliary plant for consumption test, 137
spring on governor dome, 28
Axial adjustment, 65

Baffler, 36
functions, 39
Bearings, main, 69
Blades, construction details, 44
inspecting, 104
Blading, Allis-Chalmers turbine, 48
Westinghouse-Parsons turbine, 59, 92
Blueprints, studying, 11
Buckets, moving, 14
stationary, 14
Bushings, 36

Carbon packing, 19
ring, 20
Central gravity oiling system, 111
Circulating pump fails to meet guarantee, 172
Clearance, 15, 150
adjusting, 18
between moving and stationary buckets, 4
gages, 17
measuring, 18
radial, 63
Comma lashing, 95
Condensers, 108, 131
jet, 154
Conditions for successful operation, 105
Cooling water supply limited, 177
Coupling, 127
Cover-plate, 4
-plate, lowering, 9
Curtis turbine, 11
turbine in practice, 1
setting valves, 31, 32

De Laval turbines, 118
Draining system, 105
Dummy leakage, 115
pistons, 63, 65
rings, 43, 113, 114

Equalizing pipes, 64
Exhaust end of turbine, 107
pipe, 107
Expanding nozzles, 14

Feed-pipes, 164
Flow, rate, 38
Foundation drawings, 2
rings, 44, 46
Fourth-stage wheel, 14
Franklin, Thomas, 112, 137, 154

Gages, calibrating and adjusting, 169
clearance, 17
for test work, 165
Generator, 53
Glands, examination for scale, 104
packing, 71, 77
regulation, 148
Governor, Allis-Chalmers turbine, 48
Curtis turbine, 27, 31
improved, Westinghouse-Parsons turbine, 83
-rods, adjusting, 35
safety-stop, 86
Westinghouse-Parsons turbine, 80
Grinding, 38
Guide-bearing, lower, 9
Gump, Walter B., 172

Holly draining system, 106
Horseshoe shim, 8
Hot-well regulation, 148

Inspection, 103
Intermediate, 14

Jacking ring, 8
Jet condenser, 154
Johnson, Fred L., 1, 31

Leakage, 118
Load variation, 144
Lower guide-bearing, 9
Lubrication, 51

Measuring tanks, 171
Mechanical valve-gear, 32

Nozzles, expanding, 14

Oil, 57, 103, 109
amount passing through bearings, 122
consumption, high, 175
detecting water in, 122
pressure, 122
-temperature curve, 123
Oil, testing, 110
velocity of flow, 122

Oiling, 87
system, importance, 119
Operation, Allis-Chalmers turbine, 54, 55
successful, 105
Operations in handling turbine plant, 146
Overload valve, 28

Packing, carbon, 19
glands, 71
ring, self-centering, 14
Parsons type of turbine, 41
Passage in foundation, 2
Peep-holes, 15, 18
Piping, 171
changing, 179
inspection, 164
Pressure, 63
gages, 166
in glands, 57
Pump, circulating, fails to meet guarantee, 172
inspection, 164

Radial clearance, 63
Rateau turbines, 118
Relief valves, 31
valves, importance, 159
Ring, carbon, 20
Rotor, Westinghouse-Parsons turbine, 59

Running, 99

Safety-stop, 22
-stop governor, 86
Saucer steps, 39
Screw, step-bearing, 18
step-supporting, 4
Separators, 105
Setting spindle and cylinder for minimum leakage, 115
valves in Curtis turbine, 31, 32
Shaft, holding up while removing support, 8
Shield-plate, 26, 36
Shim, horseshoe, 8
Shroud rings, 44, 46
Shrouding on buckets and intermediates, 18
Shutting down, 101
Special turbine features, 127
Spindle, lifting, 96
removing, 104
Spraying mechanism, 158
Stage valves, 28, 31
Starting up, 54, 95
Step-bearing, lowering to examine, 8
-bearing screw, 18
-blocks, 4
-lubricant, 4
-pressure, 38
-supporting screw, 4

-water, flow, 38
Stopping turbine, 56
Sub-base, 8
Superheated steam, 105

Test loads, 141
necessary features, 163
Testing oil, 110
preparing turbine for, 145
steam turbine, 112, 137, 152
Thermometer, calibrating and testing, 169
oil, 125
Thrust-block, 118
Top block, 4
Troubles with steam turbine auxiliaries, 172
Turbine features, special, 127

Vacuum, 152
raising, 107
test, 135
Valve-gear, 83
-gear, mechanical, 22, 32
operation during consumption test, 138
overload, 28
relief, 31
importance, 159
setting in Curtis turbine, 31, 32
stage, 28,31

Vapor bound pumps, 178

Water, cooling, limited, 177
in oil, detecting, 122
-measurement readings, 148
pressure, 101
service, 126
importance, 119
tests of condenser, 133
used in glands, 57, 76
Westinghouse-Parsons steam turbine, 58
Wheels, 14
lower or fourth-stage, 14
position, 18

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