POWER PLANT FROM COAL PILE TO SHAFTS OF ENGINES AND TURBINES
From the minute and specific description in Chapter III, a clear idea
will have been obtained of the power house building and its adjuncts,
as well as of the features which not only go to make it an
architectural landmark, but which adapt it specifically for the vital
function that it is called upon to perform. We now come to a review
and detailed description of the power plant equipment in its general
relation to the building, and "follow the power through" from the coal
pile to the shafts of the engines or steam turbines attached to the
dynamos which generate current for power and for light.
[Sidenote: _Coal and Ash
Handling
Equipment_]
The elements of the coal handling equipment comprise a movable
electric hoisting tower with crushing and weighing apparatus--a system
of horizontal belt conveyors, with 30-inch belts, to carry the crushed
and weighed coal along the dock and thence by tunnel underground to
the southwest corner of the power house; a system of 30-inch belt
conveyors to elevate the coal a distance of 110 feet to the top of the
boiler house, at the rate of 250 tons per hour or more, if so desired,
and a system of 20-inch belt conveyors to distribute it horizontally
over the coal bunkers. These conveyors have automatic self reversing
trippers, which distribute the coal evenly in the bunkers. For
handling different grades of coal, distributing conveyors are arranged
underneath the bunkers for delivering the coal from a particular
bunker through gates to the downtake hoppers in front of the boilers,
as hereafter described.
The equipment for removing ashes from the boiler room basement and for
storing and delivering the ashes to barges, comprises the following
elements: A system of tracks, 24 inches gauge, extending under the
ash-hopper gates in the boiler-house cellar and extending to an
elevated storage bunker at the water front. The rolling stock consists
of 24 steel cars of 2 tons capacity, having gable bottoms and side
dumping doors. Each car has two four-wheel pivoted trucks with
springs. Motive power is supplied by an electric storage battery
locomotive. The cars deliver the ashes to an elevating belt conveyor,
which fills the ash bunker. This will contain 1,000 tons, and is built
of steel with a suspension bottom lined with concrete. For delivering
stored ashes to barges, a collecting belt extends longitudinally under
the pocket, being fed by eight gates. It delivers ashes to a loading
belt conveyor, the outboard end of which is hinged so as to vary the
height of delivery and to fold up inside the wharf line when not in
use.
The coal handling system in question was adopted because any serious
interruption of service would be of short duration, as any belt, or
part of the belt mechanism, could quickly be repaired or replaced. The
system also possessed advantages with respect to the automatic even
distribution of coal in the bunkers, by means of the self reversing
trippers. These derive their power from the conveying belts. Each
conveyor has a rotary cleaning brush to cleanse the belt before it
reaches the driving pulley and they are all driven by induction
motors.
The tower frame and boom are steel. The tower rolls on two rails along
the dock and is self-propelling. The lift is unusually short; for the
reason that the weighing apparatus is removed horizontally to one side
in a separate house, instead of lying vertically below the crusher.
This arrangement reduces by 40 per cent. the lift of the bucket, which
is of the clam-shell type of forty-four cubic feet capacity. The
motive power for operating the bucket is perhaps the most massive and
powerful ever installed for such service. The main hoist is directly
connected to a 200 horse-power motor with a special system of control.
The trolley engine for hauling the bucket along the boom is also
direct coupled to a multipolar motor.
The receiving hopper has a large throat, and a steel grizzly in it
which sorts out coal small enough for the stokers and bypasses it
around the crusher. The crusher is of the two-roll type, with
relieving springs, and is operated by a motor, which is also used for
propelling the tower. The coal is weighed in duplex two-ton hoppers.
Special attention has been given to providing for the comfort and
safety of the operators. The cabs have baywindow fronts, to enable the
men to have an unobstructed view of the bucket at all times without
peering through slots in the floor. Walks and hand lines are provided
on both sides of the boom for safe inspection. The running ropes pass
through hardwood slides, which cover the slots in the engine house
roof to exclude rain and snow.
This type of motive power was selected in preference to trolley
locomotives for moving the ash cars, owing to the rapid destruction of
overhead lines and rail bonds by the action of ashes and water. The
locomotive consists of two units, each of which has four driving
wheels, and carries its own motor and battery. The use of two units
allows the locomotive to round curves with very small overhangs, as
compared with a single-body locomotive. Curves of 12 feet radius can
be turned with ease. The gross weight of the locomotive is about five
tons, all of which is available for traction.
[Sidenote: _Coal
Downtakes_]
The coal from the coal bunkers is allowed to flow down into the boiler
room through two rows of downtakes, one on each side of the central
gangway or firing place. Each bunker has eight cast-iron outlets, four
on each side, and to these outlets are bolted gate valves for shutting
off the coal from the corresponding downtakes. From these gates the
downtakes lead to hoppers which are on the economizer floor, and from
these hoppers the lower sets of downtakes extend down to the boilers.
Just above the hoppers on the economizer floor the coal downtakes are
provided with valves and chutes to feed the coal, either into the
hopper or into the distributing flight conveyor alongside of it. These
distributing conveyors, one corresponding with each row of downtakes,
permits the feeding of coal from any bunker or bunkers to all the
boilers when desired. They are the ordinary type of flight conveyor,
capable of running in either direction and provided with gates in the
bottom of the trough for feeding into the several above mentioned
hoppers. In order to eliminate the stresses that would develop in a
conveyor of the full length of the building, the conveyors are of half
the entire length, with electric driving engines in the center of each
continuous line. The installation of this conveyor system, in
connection with the coal downtakes, makes it possible to carry a
high-grade coal in some of the bunkers for use during periods of heavy
load and a cheaper grade in other bunkers for the periods of light
load.
To provide means for shutting off the coal supply to each boiler, a
small hopper is placed just over each boiler, and the downtake feeding
into it is provided with a gate at its lower end. Two vertical
downtakes extend down from the boiler hopper to the boiler room floor
or to the stokers, as the case may be, and they are hinged just below
the boiler hopper to allow their being drawn up out of the way when
necessary to inspect the boiler tubes.
[Illustration: WEST END POWER HOUSE IN COURSE OF ERECTION]
Wherever the direction of flow of the coal is changed, poke holes are
provided in the downtakes to enable the firemen to break any arching
tendency of the coal in the downtakes. All parts of the downtakes are
of cast iron, except the vertical parts in front of the boilers, which
are of wrought-iron pipe. These vertical downtakes are 10 inches in
inside diameter, while all others are 14 inches in inside diameter.
[Sidenote: _Main Boiler
Room_]
The main boiler room is designed to receive ultimately seventy-two
safety water tube three drum boilers, each having 6,008 square feet of
effective heating surface, by which the aggregate heating surface of
the boiler room will be 432,576 square feet.
There are fifty-two boilers erected in pairs, or batteries, and
between each battery is a passageway five feet wide. The boilers are
designed for a working steam pressure of 225 pounds per square inch
and for a hydraulic test pressure of 300 pounds per square inch. Each
boiler is provided with twenty-one vertical water tube sections, and
each section is fourteen tubes high. The tubes are of lap welded,
charcoal iron, 4 inches in diameter and 18 feet long. The drums are 42
inches in diameter and 23 feet and 10 inches long. All parts are of
open-hearth steel; the shell plates are 9/16 of an inch thick and the
drum head plates 11/16 inch, and in this respect the thickness of
material employed is slightly in excess of standard practice. Another
advance on standard practice is in the riveting of the circular seams,
these being lap-jointed and double riveted. All longitudinal seams are
butt-strapped, inside and outside, and secured by six rows of rivets.
Manholes are only provided for the front heads, and each front head is
provided with a special heavy bronze pad, for making connection to the
stop and check feed water valve.
[Illustration: OPERATING ROOM SHOWING CONDENSERS--POWER HOUSE]
The setting of the boiler embodies several special features which are
new in boiler erection. The boilers are set higher up from the floor
than in standard practice, the center of the drums being 19 feet above
the floor line. This feature provides a higher combustion chamber, for
either hand-fired grates or automatic stokers; and for inclined grate
stokers the fire is carried well up above the supporting girders under
the side walls, so that these girders will not be heated by proximity
to the fire.
As regards the masonry setting, practically the entire inside surface
exposed to the hot gases is lined with a high grade of fire brick. The
back of the setting, where the rear cleaning is done, is provided with
a sliding floor plate, which is used when the upper tubes are being
cleaned. There is also a door at the floor line and another at a
higher level for light and ventilation when cleaning. Over the tubes
arrangements have been made for the reception of superheating
apparatus without changing the brickwork. Where the brick walls are
constructed, at each side of the building columns at the front,
cast-iron plates are erected to a height of 8 feet on each side of the
column. An air space is provided between each cast-iron plate and the
column, which is accessible for cleaning from the boiler front; the
object of the plates and air space being to prevent the transmission
of heat to the steel columns.
An additional feature of the boiler setting consists in the employment
of a soot hopper, back of each bridge wall, by which the soot can be
discharged into ash cars in the basement. The main ash hoppers are
constructed of 1/2-inch steel plate, the design being a double
inverted pyramid with an ash gate at each inverted apex. The hoppers
are well provided with stiffening angles and tees, and the capacity of
each is about 80 cubic feet.
In front of all the boilers is a continuous platform of open-work
cast-iron plates, laid on steel beams, the level of the platform being
8 feet above the main floor. The platform connects across the firing
area, opposite the walk between the batteries, and at these points
this platform is carried between the boiler settings. At the rear of
the northerly row of boilers the platform runs along the partition
wall, between the boiler house and operating room and at intervals
doorways are provided which open into the pump area. The level of the
platform is even with that of the main operating room floor, so that
it may be freely used by the water tenders and by the operating
engineers without being obstructed by the firemen or their tools. The
platform in front of the boilers will also be used for cleaning
purposes, and, in this respect, it will do away with the unsightly and
objectionable scaffolds usually employed for this work. The water
tenders will also be brought nearer to the water columns than when
operating on the main floor. The feed-water valves will be regulated
from the platform, as well as the speed of the boiler-feed pumps.
Following European practice, each boiler is provided with two water
columns, one on each outside drum, and each boiler will have one steam
gauge above the platform for the water tenders and one below the
platform for the firemen. The stop and check valves on each boiler
drum have been made specially heavy for the requirements of this power
house, and this special increase of weight has been applied to all the
several minor boiler fittings.
Hand-fired grates of the shaking pattern have been furnished for
thirty-six boilers, and for each of these grates a special lower front
has been constructed. These fronts are of sheet steel, and the coal
passes down to the floor through two steel buckstays which have been
enlarged for the purpose. There are three firing doors and the sill of
each door is 36 inches above the floor. The gate area of the
hand-fired grates is 100 square feet, being 8 feet deep by 12 feet 6
inches wide.
The twelve boilers, which will receive coal from the coal bunker
located between the fourth and fifth chimneys, have been furnished
with automatic stokers.
It is proposed to employ superheaters to the entire boiler plant.
The boiler-room ceiling has been made especially high, and in this
respect the room differs from most power houses of similar
construction. The distance from the floor to the ceiling is 35 feet,
and from the floor plates over the boilers to the ceiling is 13 feet.
Over each boiler is an opening to the economizer floor above, covered
with an iron grating. The height of the room, as well as the feature
of these openings, and the stairway wells and with the large extent of
window opening in the south wall, will make the room light and
especially well ventilated. Under these conditions the intense heat
usually encountered over boilers will largely be obviated.
In addition to making provisions for the air to escape from the upper
part of the boiler room, arrangements have been provided for allowing
the air to enter at the bottom. This inflow of air will take place
through the southerly row of basement windows, which extend above the
boiler room floor, and through the wrought-iron open-work floor
construction extending along in the rear of the northerly row of
boilers.
A noteworthy feature of the boiler room is the 10-ton hand-power
crane, which travels along in the central aisle through the entire
length of the structure. This crane is used for erection and for heavy
repair, and its use has greatly assisted the speedy assembling of the
boiler plant.
[Sidenote: _Blowers and
Air Ducts_]
In order to burn the finer grades of anthracite coal in sufficient
quantities to obtain boiler rating with the hand-fired grates, and in
order to secure a large excess over boiler rating with other coals, a
system of blowers and air ducts has been provided in the basement
under the boilers. One blower is selected for every three boilers,
with arrangements for supplying all six boilers from one blower.
The blowers are 11 feet high above the floor and 5 feet 6 inches wide
at the floor line. Each blower is direct-connected to a two crank
7-1/2 x 13 x 6-1/2-inch upright, automatic, compound, steam engine of
the self-enclosed type, and is to provide a sufficient amount of air
to burn 10,000 pounds of combustible per hour with 2 inches of water
pressure in the ash pits.
[Sidenote: _Smoke Flues
and
Economizers_]
The smoke flue and economizer construction throughout the building is
of uniform design, or, in other words, the smoke flue and economizer
system for one chimney is identical with that for every other chimney.
In each case, the system is symmetrically arranged about its
respective chimney, as can be seen by reference to the plans.
The twelve boilers for each chimney are each provided with two round
smoke uptakes, which carry the products of combustion upward to the
main smoke flue system on the economizer floor. A main smoke flue is
provided for each group of three boilers, and each pair of main smoke
flues join together on the center line of the chimney, where in each
case one common flue carries the gases into the side of the chimney.
The two common flues last mentioned enter at opposite sides of the
chimney. The main flues are arranged and fitted with dampers, so that
the gases can pass directly to the chimney, or else they can be
diverted through the economizers and thence reach the chimney.
The uptakes from each boiler are constructed of 3/8-inch plate and
each is lined with radial hollow brick 4 inches thick. Each is
provided with a damper which operates on a shaft turning in roller
bearings. The uptakes rest on iron beams at the bottom, and at the
top, where they join the main flue, means are provided to take up
expansion and contraction.
The main flue, which rests on the economizer floor, is what might be
called a steel box, constructed of 3/8-inch plate, 6 feet 4 inches
wide and 13 feet high. The bottom is lined with brick laid flat and
the sides with brick walls 8 inches thick, and the top is formed of
brick arches sprung between.
[Sidenote: _Steam Piping_]
The sectional plan adopted for the power house has made a uniform and
simple arrangement of steam piping possible, with the piping for each
section, except that of the turbine bay, identical with that for every
other section. Starting with the six boilers for one main engine, the
steam piping may be described as follows: A cross-over pipe is erected
on each boiler, by means of which and a combination of valves and
fittings the steam may be passed through the superheater. In the
delivery from each boiler there is a quick-closing 9-inch valve, which
can be closed from the boiler room floor by hand or from a distant
point individually or in groups of six. Risers with 9-inch
wrought-iron goose necks connect each boiler to the steam main, where
9-inch angle valves are inserted in each boiler connection. These
valves can be closed from the platform over the boilers, and are
grouped three over one set of three boilers and three over the
opposite set.
The main from the six boilers is carried directly across the boiler
house in a straight line to a point in the pipe area where it rises to
connect to the two 14-inch steam downtakes to the engine throttles. At
this point the steam can also be led downward to a manifold to which
the compensating tie lines are connected. These compensating lines are
run lengthwise through the power house for the purpose of joining the
systems together, as desired. The two downtakes to the engine
throttles drop to the basement, where each, through a goose neck,
delivers into a receiver and separating tank and from the tank through
a second goose neck into the corresponding throttle.
A quick-closing valve appears at the point where the 17-inch pipe
divides into the two 14-inch downtakes and a similar valve is provided
at the point where the main connects to the manifold. The first valve
will close the steam to the engine and the second will control the
flow of steam to and from the manifold. These valves can be operated
by hand from a platform located on the wall inside the engine room, or
they can be closed from a distant point by hydraulic apparatus. In the
event of accident the piping to any engine can be quickly cut out or
that system of piping can quickly be disconnected from the
compensating system.
The pipe area containing, as mentioned, the various valves described,
together with the manifolds and compensating pipes, is divided by
means of cross-walls into sections corresponding to each pair of main
engines. Each section is thus separated from those adjoining, so that
any escape of steam in one section can be localized and, by means of
the quick-closing valves, the piping for the corresponding pair of
main engines can be disconnected from the rest of the power house.
[Illustration: VIEW FROM TOP OF CHIMNEY SHOWING WATER FRONTAGE--POWER
HOUSE]
All cast iron used in the fittings is called air-furnace iron, which
is a semi-steel and tougher than ordinary iron. All line and bent pipe
is of wrought iron, and the flanges are loose and made of wrought
steel. The shell of the pipe is bent over the face of the flange. All
the joints in the main steam line, above 2-1/2 inches in size, are
ground joints, metal to metal, no gaskets being used.
Unlike the flanges ordinarily used in this country, special extra
strong proportions have been adopted, and it may be said that all
flanges and bolts used are 50 per cent. heavier than the so-called
extra heavy proportions used in this country.
[Sidenote: _Water Piping_]
The feed water will enter the building at three points, the largest
water service being 12 inches in diameter, which enters the structure
at its southeast corner. The water first passes through fish traps
and thence through meters, and from them to the main reservoir tanks,
arranged along the center of the boiler house basement. The water is
allowed to flow into each tank by means of an automatic float valve.
The water will be partly heated in these reservoir tanks by means of
hot water discharged from high-pressure steam traps. In this way the
heat contained in the drainage from the high-pressure steam is, for
the most part, returned to the boilers. From the reservoir tanks the
water is conducted to the feed-water pumps, by which it is discharged
through feed-water heaters where it is further heated by the exhaust
steam from the condensing and feed-water pumps. From the feed-water
heaters the water will be carried direct to the boilers; or through
the economizer system to be further heated by the waste gases from the
boilers.
[Illustration: PORTION OF MAIN STEAM PIPING IN PIPE AREA]
Like the steam-pipe system, the feed-water piping is laid out on the
sectional plan, the piping for the several sections being identical,
except for the connections from the street service to the reservoir
tanks. The feed-water piping is constructed wholly of cast iron,
except the piping above the floor line to the boilers, which is of
extra heavy semi-annealed brass with extra heavy cast-iron fittings.
[Sidenote: _Engine and
Turbine
Equipment_]
The engine and turbine equipment under contract embraces nine 8,000 to
11,000 horse power main engines, direct-connected to 5,000 kilowatt
generators, three steam turbines, direct-connected to 1,875 kilowatt
lighting generators and two 400 horse power engines, direct-connected
to 250 kilowatt exciter generators.
[Sidenote: _Main Engines_]
The main engines are similar in type to those installed in the 74th
Street power house of the Manhattan Division of the Interborough Rapid
Transit Company, i. e., each consists of two component compound
engines, both connected to a common shaft, with the generator placed
between the two component engines. The type of engine is now well
known and will not be described in detail, but as a comparison of
various dimensions and features of the Manhattan and Rapid Transit
engines may be of interest, the accompanying tabulation is submitted:
Manhattan. Rapid Transit.
Diameter of high-pressure cylinders, inches, 44 42
Diameter of low-pressure cylinders, inches, 88 86
Stroke, inches, 60 60
Speed, revolutions per minute, 75 75
Steam pressure at throttle, pounds, 150 175
Indicated horse power at best efficiency, 7,500 7,500
Diameter of low-pressure piston rods, inches, 8 10
Diameter of high-pressure piston rods, inches, 8 10
Diameter of crank pin, inches, 18 20
Length of crank pin, inches, 18 18
Double Ported Single Ported
Type of Low-Pressure Valves. Corliss Corliss
Type of High-Pressure Valves. Corliss Poppet Type
Diameter of shaft in journals, inches, 34 34
Length of journals, inches, 60 60
Diameter of shaft in hub of revolving
element, inches 37-1/16 37-1/16
The guarantees under which the main engines are being furnished, and
which will govern their acceptance by the purchaser, are in substance
as follows: First. The engine will be capable of operating
continuously when indicating 11,000 horse power with 175 lbs. of steam
pressure, a speed of 75 revolutions and a 26-inch vacuum without
normal wear, jar, noise, or other objectionable results. Second. It
will be suitably proportioned to withstand in a serviceable manner all
sudden fluctuations of load as are usual and incidental to the
generation of electrical energy for railway purposes. Third. It will
be capable of operating with an atmospheric exhaust with two pounds
back pressure at the low pressure cylinders, and when so operating,
will fulfill all the operating requirements, except as to economy and
capacity. Fourth. It will be proportioned so that when occasion shall
require it can be operated with a steam pressure at the throttles of
200 pounds above atmospheric pressure under the before mentioned
conditions of the speed and vacuum. Fifth. It will be proportioned so
that it can be operated with steam pressure at the throttle of 200
pounds above atmospheric pressure under the before mentioned condition
as to speed when exhausting in the atmosphere. Sixth. The engine will
operate successfully with a steam pressure at the throttle of 175
pounds above atmosphere, should the temperature of the steam be
maintained at the throttle at from 450 to 500 degrees Fahr. Seventh.
It will not require more than 12-1/4 pounds of dry steam per indicated
horse power per hour, when indicating 7,500 horse power at 75
revolutions per minute, when the vacuum of 26 inches at the low
pressure cylinders, with a steam pressure at the throttle of 175
pounds and with saturated steam at the normal temperature due to its
pressure. The guarantee includes all of the steam used by the engine
or by the jackets or reheater.
The new features contained within the engine construction are
principally: First, the novel construction of the high-pressure
cylinders, by which only a small strain is transmitted through the
valve chamber between the cylinder and the slide-surface casting.
This is accomplished by employing heavy bolts, which bolt the shell of
the cylinder casting to the slide-surface casting, said bolts being
carried past and outside the valve chamber. Second, the use of poppet
valves, which are operated in a very simple manner from a wrist plate
on the side of the cylinder, the connections from the valves to the
wrist plate and the connections from the wrist plate to the eccentric
being similar to the parts usually employed for the operation of
Corliss valves.
Unlike the Manhattan engines, the main steam pipes are carried to the
high-pressure cylinders under the floor and not above it. Another
modification consists in the use of an adjustable strap for the
crank-pin boxes instead of the marine style of construction at the
crank-pin end of the connecting rod.
The weight of the revolving field is about 335,000 pounds, which gives
a flywheel effect of about 350,000 pounds at a radius of gyration of
11 feet, and with this flywheel inertia the engine is designed so that
any point on the revolving element shall not, in operation, lag behind
nor forge ahead of the position that it would have if the speed were
absolutely uniform, by an amount greater than one-eighth of a natural
degree.
[Sidenote: _Turbo-Generators_]
Arrangements have been made for the erection of four turbo generators,
but only three have been ordered. They are of the multiple expansion
parallel flow type, consisting of two turbines arranged tandem
compound. When operating at full load each of the two turbines,
comprising one unit, will develop approximately equal power for direct
connection to an alternator giving 7,200 alternations per minute at
11,000 volts and at a speed of 1,200 revolutions per minute. Each unit
will have a normal output of 1,700 electrical horse power with a steam
pressure of 175 pounds at the throttle and a vacuum in the exhaust
pipe of 27 inches, measured by a mercury column and referred to a
barometric pressure of 30 inches. The turbine is guaranteed to operate
satisfactorily with steam superheated to 450 degrees Fahrenheit. The
economy guaranteed under the foregoing conditions as to initial and
terminal pressure and speed is as follows: Full load of 1,250
kilowatts, 15.7 pounds of steam per electrical horse-power hour;
three-quarter load, 937-1/2 kilowatts, 16.6 pounds per electrical
horse-power hour; one-half load, 625 kilowatts, 18.3 pounds; and
one-quarter load, 312-1/2 kilowatts, 23.2 pounds. When operating under
the conditions of speed and steam pressure mentioned, but with a
pressure in the exhaust pipe of 27 inches vacuum by mercury column
(referred to 30 inches barometer), and with steam at the throttle
superheated 75 degrees Fahrenheit above the temperature of saturated
steam at that pressure, the guaranteed steam consumption is as
follows: Full load, 1,250 kilowatts, 13.8 pounds per electrical
horse-power hour; three-quarter load, 937-1/2 kilowatts, 14.6 pounds;
one-half load, 625 kilowatts, 16.2 pounds; and one-quarter load,
312-1/2 kilowatts, 20.8 pounds.
[Sidenote: _Exciter
Engines_]
The two exciter engines are each direct connected to a 250 kilowatt
direct current generator. Each engine is a vertical quarter-crank
compound engine with a 17-inch high pressure cylinder and a 27-inch
low-pressure cylinder with a common 24-inch stroke. The engines will
be non-condensing, for the reason that extreme reliability is desired
at the expense of some economy. They will operate at best efficiency
when indicating 400 horse power at a speed of 150 revolutions per
minute with a steam pressure of 175 pounds at the throttle. Each
engine will have a maximum of 600 indicated horse power.
[Sidenote: _Condensing
Equipment_]
Each engine unit is supplied with its own condenser equipment,
consisting of two barometric condensing chambers, each attached as
closely as possible to its respective low-pressure cylinder. For each
engine also is provided a vertical circulating pump along with a
vacuum pump and, for the sake of flexibility, the pumps are cross
connected with those of other engines and can be used interchangeably.
The circulating pumps are vertical, cross compound pumping engines
with outside packed plungers. Their foundations are upon the basement
floor level and the steam cylinders extend above the engine-room
floor; the starting valves and control of speed is therefore entirely
under the supervision of the engineer. Each pump has a normal capacity
of 10,000,000 gallons of water per day, so that the total pumping
capacity of all the pumps is 120,000,000 gallons per day. While the
head against which these pumps will be required to work, when assisted
by the vacuum in the condenser, is much less than the total lift from
low tide water to the entrance into the condensing chambers, they are
so designed as to be ready to deliver the full quantity the full
height, if for any reason the assistance of the vacuum should be lost
or not available at times of starting up. A temporary overload can but
reduce the vacuum only for a short time and the fluctuations of the
tide, or even a complete loss of vacuum cannot interfere with the
constant supply of water, the governor simply admitting to the
cylinders the proper amount of steam to do the work. The high-pressure
steam cylinder is 10 inches in diameter and the low-pressure is 20
inches; the two double-acting water plungers are each 20 inches in
diameter, and the stroke is 30 inches for all. The water ends are
composition fitted for salt water and have valve decks and plungers
entirely of that material.
[Illustration: COAL UNLOADING TOWER ON WEST 58TH STREET PIER]
The dry vacuum pumps are of the vertical form, and each is located
alongside of the corresponding circulating pump. The steam cylinders
also project above the engine-room floor. The vacuum cylinder is
immediately below the steam cylinder and has a valve that is
mechanically operated by an eccentric on the shaft. These pumps are of
the close-clearance type, and, while controlled by a governor, can be
changed in speed while running to any determined rate.
[Sidenote: _Exhaust
Piping_]
From each atmospheric exhaust valve, which is direct-connected to the
condensing chamber at each low-pressure cylinder, is run downward a
30-inch riveted-steel exhaust pipe. At a point just under the
engine-room floor the exhaust pipe is carried horizontally around the
engine foundations, the two from each pair of engines uniting in a
40-inch riser to the roof. This riser is between the pair of engines
and back of the high-pressure cylinder, thus passing through the
so-called pipe area, where it also receives exhaust steam from the
pump auxiliaries. At the roof the 40-inch riser is run into a 48-inch
stand pipe. This is capped with an exhaust head, the top of which is
35 feet above the roof.
All the exhaust piping 30 inches in diameter and over is
longitudinally riveted steel with cast-iron flanges riveted on to it.
Expansion joints are provided where necessary to relieve the piping
from the strains due to expansion and contraction, and where the
joints are located near the engine and generator they are of
corrugated copper. The expansion joints in the 40-inch risers above
the pipe area are ordinarily packed slip joints.
The exhaust piping from the auxiliaries is carried directly up into
the pipe area, where it is connected with a feed-water heater, with
means for by-passing the latter. Beyond the heater it joins the
40-inch riser to the roof. The feed-water heaters are three-pass,
vertical, water-tube heaters, designed for a working water pressure of
225 pounds per square inch.
The design of the atmospheric relief valve received special
consideration. A lever is provided to assist the valve to close, while
a dash pot prevents a too quick action in either direction.
[Sidenote: _Compressed
Air_]
The power house will be provided with a system for supplying
compressed air to various points about the structure for cleaning
electrical machinery and for such other purposes as may arise. It will
also be used for operating whistles employed for signaling. The air is
supplied to reservoir tanks by two vertical, two-stage,
electric-driven air compressors.
[Sidenote: _Oil System_]
For the lubrication of the engines an extensive oil distributing and
filtering system is provided. Filtered oil will be supplied under
pressure from elevated storage tanks, with a piping system leading to
all the various journals. The piping to the engines is constructed on
a duplicate, or crib, system, by which the supply of oil cannot be
interrupted by a break in any one pipe. The oil on leaving the engines
is conducted to the filtering tanks. A pumping equipment then
redelivers the oil to the elevated storage tanks.
All piping carrying filtered oil is of brass and fittings are inserted
at proper pipes to facilitate cleaning. The immediate installation
includes two oil filtering tanks at the easterly end of the power
house, but the completed plant contemplates the addition of two extra
filtering tanks at the westerly end of the structure.
[Sidenote: _Cranes, Shops,
Etc._]
The power house is provided with the following traveling cranes: For
the operating room: One 60-ton electric traveling crane and one 25-ton
electric traveling crane. For the area over the oil switches: one
10-ton hand-operated crane. For the center aisle of the boiler room:
one 10-ton hand-operated crane. The span of both of the electric
cranes is 74 feet 4 inches and both cranes operate over the entire
length of the structure.
The 60-ton crane has two trolleys, each with a lifting capacity, for
regular load, of 50 tons. Each trolley is also provided with an
auxiliary hoist of 10 tons capacity. When loaded, the crane can
operate at the following speeds: Bridge, 200 feet per minute;
trolley, 100 feet per minute; main hoist, 10 feet per minute; and
auxiliary hoist, 30 feet per minute. The 25-ton crane is provided with
one trolley, having a lifting capacity, for regular load, of 25 tons,
together with auxiliary hoist of 5 tons. When loaded, the crane can
operate at the following speeds: bridge, 250 feet per minute; trolley,
100 feet per minute; main hoist, 12 feet per minute; and auxiliary
hoist, 28 feet per minute.
The power house is provided with an extensive tool equipment for a
repair and machine shop, which is located on the main gallery at the
northerly side of the operating room.
[Illustration: 5,000 K. W. ALTERNATOR--MAIN POWER HOUSE]