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74th Street Power Plant
| Firmenname | 74th Street Power Plant |
| Ortssitz | New York (N.Y.) |
| Straße | 74th Street |
| Internet-Seite | http://mcnyblog.org/2012/06/12/construction-of-the-74th-street-power-station/ |
| Art des Unternehmens | Elektrizitätswerk |
| Anmerkungen | Gelegen am East River zwischen der 74th und 75th Street. Gebaut für die "Manhattan Elevated Railway Company" zur Versorgung der Hochbahnen im Bereich Second, Third, Sixth und Ninth Avenues. Gehört seit 1959 zu: "Consolidated Edison Co.-New York Inc.). Das Gebäude ist 200 x 500 ft. (61 x 150 m) groß (s.d.) |
| Quellenangaben | Annual electric generator report, 01.01.1997. Existing plants (Internet); http://www.ieeeghn.org [New York electr. handbook (1904) 247] |
| Hinweise | [New York electr. handbook (1904) 246]: Ansicht; 248: Innenansicht |
| Zeit |
Ereignis |
| 1899 |
Beginn der Erbauarbeiten |
| 11.10.1900 |
Zwei Schornsteine sind in halber Höhe fertig. Von den beiden anderen stehen die Sockel. |
| 20.06.1901 |
Der Aufbau der Maschinen beginnt |
| 1902 |
Das Werk ist voll in Betrieb |
| 20.02.1902 |
Die meisten Maschinen sind bereits aufgestellt. |
| 1911 |
Aufstellung einer 7.500-kW-Westinghouse-Dampfturbine mit Wechselstromgenerator |
| 1915 |
Es gibt Pläne für den Ersatz von vier der Original-Maschinen durch zwei Dampfturbosätze mit je 30.000 kW, bestehend aus einer Hochdruckturbine (n= 1500 U/min) und einer Niederdruckturbine (n= 750 U/min), jede treibt einen 10.000-kW-Generator. |
| 1917 |
Einrichtung einer Wechselstrom-Hochspannungsübertragung mit dem Kraftwerk in der 59th Street Station der "Interborough Rapid Transit Company" |
| 1918 |
Es wird eine ungewöhnliche Turbine (60 MW) aufgestellt. Der Dampf der Hochdruckstufe verzweigt sich in zwei Niederdruckstufen, jede Stufe gekuppelt mit einem 20-MW-Generator. |
| 1959 |
Übernahme durch die "Consolidated Edison Company". Das Werk setzt noch für einige Zeit die Versorgung mit 25 Hz zu den Unterwerken Nr. 21 (Brooklyn) und Nr. 26 (Queens) der IRT fort. |
| 1987 |
Die zwei Westinghouse-Turbinen T 9 und T 10 (60 Hz) gehen außer Betrieb |
| 1995 |
Das Werk produziert von 104 MW Leistung, aber nicht mehr für die Versorgung elektrischer Bahnen |
| 1999 |
Die Turbine T 11 (General Electric, 25 Hz) bleibt bis 1999 in Betrieb, da sie 25-Hz-Wechselstrom für die Signalanlagen der Untergrundbahnen der IRT und BMT liefert. Danach beginnt die "New York City Transit Authority" die Umstellung auf statische Umrichter. Sie diente auch als Vorschaltturbine von p= 1200 psi auf 150 bis 200 psi (84 at auf 10,5 bis 14 at) für die Fernwärmeversorgung. Der Überschußstrom wurde durch einen rotierenden Umrichter von 25 Hz in 60 Hz umgewandelt. |
| Produkt |
ab |
Bem. |
bis |
Bem. |
Kommentar |
| elektrische Energie |
1902 |
Beginn (voll in Betrieb) |
1996 |
[Ann. gener. report] |
Beginn: s.a. Inbetriebnahmejahre der Generatoren in Tabelle SYSADM.USA_EL_GEN |
Zeit = 1: Zeitpunkt unbekannt
| Zeit |
Bezug |
Abfolge |
andere Firma |
Kommentar |
| 1 |
Nebenwerk |
zuvor |
Consolidated Edison Co-New York Inc |
Zu EVU ... gehört Kraftwerk ... (in den USA) |
| ZEIT | 1904 |
| THEMA | Beschreibung |
| TEXT | The power station has a distinctively massive and symmetrical appearance, for the exterior walls, relieved by high arched windows, are carried around the entire building at a uniform height, thus preserving the unity of design. Below the windows, which are about twenty-five feet above the ground, the walls are faced with rough finished granite, and above this line moulded bricks are used. The roof is covered with red tile, with continuous monitor windows above engine and boiler rooms.
The building is 204 feet wide and extends 395 feet along 74th Street and 413 feet along 75th Street. Between the east wall and the dock, a space of eighty-five feet has been reserved by the city for the future construction of Exterior Street. The property purchased for the power station extends back from the west wall a sufficient distance so that the building may be extended to contain additional power equipment.
The foundations rest on bed rock, in which much excavation was required in order to arrive at a uniform level. The building is of brick and steel fireproof construction throughout. Combustible material has been avoided even in the window frames and sashes, which are of cast iron, and all doors and wooden office partitions are sheathed either with copper or galvanized iron.
A brick partition wall divides the engine room, which is ninety-three feet six inches wide, from the boiler
room, which is one hundred and four feet two inches wide.
The four stacks are each seventeen feet inside diameter and 278 feet high above the basement floor, and 267 feet above the grates of the lower boilers. The base of the stack is octagonal in shape to a point above the flue opening of the upper tier of boilers seventy-three feet from the basement floor. The walls of the base are five feet thick, with a lining of hollow fire brick supported on corbeled shelves ten feet apart to allow for
expansion.
The circular shaft is built of Custodis brick, which are perforated with one-inch square holes. These holes serve to reduce the weight of the brick and also provide dead air spaces, which decrease the amount of heat carried through the walls of the stack.
The power generating machinery has been arranged in eight distinct units, each unit consisting of one engine and condenser, four batteries of boilers, and one boiler feed pump. This arrangement lends itself most favorably to the construction of the building, as it allows uniform spacing and duplication of columns and beams. It also simplifies the piping, which is identical for the eight units, and provides, between each engine and its corresponding boilers, the most direct route for the steam.
The prime movers are eight Allis-Chalmers engines, each of 8,000 horse-power. Each of these engines has a straight shaft supported by two bearings with crank discs at each end and with the rotating element of the alternator located centrally. A high pressure cylinder, placed horizontally, and a low pressure cylinder, placed vertically, is attached to each crank disc, the connecting rods being attached side by side to one crank pin. The crank pin at one end is placed 135 degrees ahead of the crank pin at the other end of the shaft. During each revolution the shaft receives two impulses from each of the four cylinders, thus producing a very uniform rotative effect. The cylinders are forty-four and eighty-eight inches in diameter, respectively, with five-foot stroke and the normal speed is seventy-five revolutions a minute. Valves are of the Reynolds-Corliss automatic type and separate eccentrics are used for operating the valves on the high and low pressure cylinders. A ball governor, with an oil operated relay, controls the point of cut-off of the high and low pressure cylinders. The relay consists of a small cylinder with a piston connected to the engine valve gear. The ball governor is arranged so that its movement opens or closes valves which admit oil under pressure to the relay cylinder. The relay, therefore, serves to make the governing of the engine more sensitive, as the work of moving the engine valve gears is done by the oil piston. The variation in speed, when running in regular service, is guaranteed not to exceed three-fifths of one degree in one revolution.
The steam consumption, when developing 8,000 Brake Horse Power with 150 pounds steam, twenty-six inches vacuum, at seventy-five revolutions a minute, is guaranteed not to exceed thirteen pounds steam per indicated horse-power per hour.
Eight barometric type jet condensers are installed with the condensing cones placed as near as possible to the discharge opening of each of the low pressure cylinders. Between the top of the cone and the cylinder opening, a special "Tee" is placed to allow for the atmospheric exhaust connection. The bottom of the cone is about thirty-four feet above extreme high water, and the discharge tube is carried to the bottom of the discharge tunnel, so that the end of the pipe is always submerged. The condensing water is supplied to each of the 8.000-H.P. engines by a centrifugal circulating pump direct-connected to a single cylinder engine, the exhaust of which is piped to the receiver of the main engine. In order to provide against a failure of any one of the centrifugal pumps, a duplex steam-driven pump, having a capacity of 7.500 gallons per minute, is installed and connected to a twenty-four-inch pipe running the entire length of the building, from which connections are made to the injection pipes of each condenser. The vacuum is equalized in the condensing chambers by the use of an equalizing pipe, twelve inches in diameter, which connects the exhaust pipes above the condensers. Dry air pumps are not required, as a high degree
of vacuum is obtained without their use. A motor-driven vacuum pump has, however, been installed with pipes connecting to the discharge of each of the centrifugal pumps, which serves to prime the pumps. The spray nozzle in the condensing chamber consists of an umbrella-shaped casting, through the center of which the injection water passes. A cone-shaped casting, supported in the centre of the injection pipe on a vertical spindle, causes the water to be distributed uniformly over the umbrella-shaped casting. The advantage of this form of spray nozzle is that there are no small openings to become clogged with foreign matter held in suspension in the injection water, and anything that can pass through the four-inch mesh screen will safely pass through the condenser. The cost of maintenance on this type of condenser is extremely low, as there are no valve seats, springs or tubes to get out of order. The degree of vacuum produced averages twenty-eight inches, about two inches less than the height of the barometer taken simultaneously. The water for condensing the steam is taken from the river through a tunnel built below the basement floor of the engine room along the 74th Street side. This tunnel is rectangular in section. 8 ft. 6 in. wide and 14 ft. 3 in deep. Parallel to this tunnel is a smaller tunnel, five feet wide and of the same depth,
which carries away the discharge w'ater from the condensers. At the river ends, these tunnels are separated eighty-five feet to prevent the warm water from the discharge tunnel returning through the intake tunnel. At the mouth of the intake tunnel, a set of double screens, with four-inch mesh, is built to prevent the passage of floating material into the tunnel. It is necessary to raise these screens at least once each day to remove the quantity of refuse which clings to the gratings.
The boiler equipment consists of sixty-four Babcock & Wilcox horizontal water tube boilers, each rated at 520 boiler horse-power at thirty pounds steam per H.P. per hour. Eight additional boilers of 600 B.H.P. each were recently installed and will be used for the boilers are placed on two floors with centre firing aisles which run longitudinally with the building. They arc built in batteries of two and are supported on the colums of the building independent of the brick walls and floors. Eight boilers, four on each floor, occupy the space opposite one engine unit and normally supply steam for this unit. Each boiler has 5,200 square feet of heating surface, and the mechanical stoker has ninety-four square feet of grate area. The normal steam pressure carried at the boilers is 165 pounds above atmosphere, but the boilers are built to safely carry 200 pounds. The actual evaporation of the boilers with coal having a heat value of 14,000 British thermal units per pound, and with feed water at an average temperature of 188°F, averages 9.18 pounds of water per pound of coal.
The Roney mechanical stokers, with which the boilers are fitted, are capable of burning either anthracite or bituminous coal, or a mixture of the two. The coal is delivered to the stokers through iron pipes from the coal bunkers at the top of the building and requires no manual handling. An economizer, for heating the feed water, is pro
vided for each set of two batteries of boilers in the original installation, making sixteen economizers in all. Each economizer is placed in the rear of its set of boilers, with a smoke flue betw^een the inner wall of the economizer and the rear wall of the boilers. This flue is provided with dampers, so that the flue gases may be led through the economizer or passed directly to the stack.
For the first three months in the year 1904, the average temperature of the water at the city water main was 34,8°F; the temperature at which it left the surge tank was 71,7°F, and the temperature on leaving the economizers was 182,3°F., showing an increase of 110,6°F, due to the use of the economizers.
Sixteen blowers are installed in the boiler room for the purpose of furnishing forced draft in case anthracite
coal is used. Each blower has a capacity of 57,000 cubic feet of air at a pressure of one ounce per square inch,
and is driven by a direct connected twenty-five horse-power induction motor. Eight pumps, each having a capacity of 360 gallons per minute, are installed in the centre aisle of the boiler room basement for supplying water to the boilers. Each pump consists of three single acting cylinders driven by gearing from a sixty-five horse-power, 500
volt, shunt-wound, motor. The steam piping is arranged in eight sections, each section connecting one engine with four batteries of boilers, two on the upper and two on the lower floor. The two batteries on each floor are connected to a short header, eighteen inches in diameter, and these headers are connected between adjacent sections by fourteen-inch equalizing pipes, bent at large radius. For each engine, a steam reservoir, thirty-six inches
in diameter and twenty-four feet long, is provided. The expansion and contraction is provided for by means of pipes with bends of large radius. The boiler feed piping is arranged on a ring system so that, in case of an accident to any portion of the piping, the boilers may be supplied by the duplicate connection. All of the valves used in both high and low pressure piping are made with adjustable wedge gates and with bronze seats.
The amount of coal required for the operation of the power station during the winter months is about 700 tons per day. This coal is brought to the power station dock in barges, from which the coal is unloaded by means of a ton-and-a-half clam-shell bucket operated by a hoisting engine. This bucket is elevated about fifty feet to the top of the coal tower, where the coal is discharged into crushers, which break it to a size suitable for use in the automatic stokers. The coal then drops into weighing hoppers, where it is weighed before going to the boilers. It is then elevated by means of conveyors to the top of the tower and is delivered into bucket conveyors which run the entire length of the boiler room, and these conveyors deliver to three separate coal bunkers built above the upper tier of boilers.
After the coal is burned, the ashes drop to the basement through rectangular cast iron pipes and, by opening valves at the lower ends of these pipes, the ashes are delivered into iron cars and an electric mining locomotive is used to pull these cars to a point at the east end of the building, where they are dumped into a hopper which loads the ashes into a line of bucket conveyors. These elevate and carry the ashes across the bridge to the tower containing ash storage bins. When a sufficient quatity of ashes has accumulated, these bins are emptied into barges which transport the ashes away. A movable coal tower, provided with belt conveyors, has recently been installed in addition to the apparatus already described. The movable tower obviates the necessity of moving the barge from time to time as coal is unloaded, thereby saving much time and labor.
The engine room is provided with an electric crane which is capable of handling the heaviest single piece of machinery installed. The crane has one fifty-ton and one fifteen-ton hoist.
The eight Westinghouse alternators at the 74th Street power station were, at the time of their erection, the largest engine-driven dynamos that had ever been built. The rated output of each alternator is 5.000 kW, but they are designed to carry an overload of fifty per cent, for two hours with a temperature rise not to exceed 55°C, and in service they are frequently loaded to this amount for short spaces of time. The accompanying diagram shows a representative load at the 74th Street power station, taken on January 18, 1904 on a cold day when, in addition to the power for moving cars, a considerable quantity of power was required for car heaters. The diagram indicates that, during rush hours, the eight alternators were delivering to the line from 40.000 to 47.000 kilowatts, and that, in addition from 5.000 to 6.000 kilowatts was being supplied by the Kingsbridge station of the Metropolitan Street Railway Company.
In order to meet the increasing demands for power caused by the rapidly increasing traffic, a 5.500-kilowatt
alternator, driven by a Parson's steam turbine, is soon to be installed at the 74th Street station, and additional
power will also be transmitted from the new Interborough power station at 58th Street, as soon as this station is in operation. Reference to the load diagram shows that, between the hours of four and six-thirty in the morning, the
load increased very rapidly from 5.000 to 40.000 kilowatts. Consideration of this quickly rising load was one of the determining factors in the choice of units of 5.000 kilowatts output. Even with units of this size, it is necessary to start one every twenty minutes in order to anticipate the morning load.
The external armature frame of the alternator is forty-two feet high, and is made in six sections bolted together. This frame is bored to receive the laminated steel plates which form the armature core. The winding is three-phase, and, at the normal output of 5,000 kilowatts at 11,000 volts with non-inductive load, the current per phase is 263 amperes. The normal speed is seventy-five revolutions a minute, and the current generated has 3.000 alternations per minute, or twenty-five cycles per second. The armature winding consists of insulated copper bars placed in partially
closed slots, there being four slots per phase per pole and three bars in each slot. The insulation of the armature winding was subjected to a test of 25.000 volts alternating for thirty minutes before each machine was accepted by the purchaser. The forty field poles are built up of laminated steel plates secured to the periphery of the steel plate fly wheel, and the outside diameter of the poles is thirty-two feet. The fly wheel effect of this rotating element is 370.000 pounds at 11.7 feet radius. The field windings consist of copper straps wound on edge, one layer deep, with insulating material cemented between the turns. Copper wedges are driven into place between adjacent pole tips after the coils have been put on. These copper wedges serve to hold the coils in place and also act as a magnetic damper to check any tendency toward variation in angular velocity. The exciting current required in the field coils when the armature is delivering full rated output, is 225 amperes at 200 volts. A field rheostat, with motor driven face plate, is provided with each alternator for regulating the potential. The insulation of the field
coils is designed to withstand a test of 2,500 volts, alternating, for one minute.
The electrical efficiency of the alternator, determined by shop tests, is 96,68 per cent, at half load, 97,97 per
cent, at full load, and 98,15 per cent, at 25 per cent, overload.
Four exciter generators are installed for supplying current to the alternator fields. Each generator is of 250 kilowatts output, or 1,000 amperes at 250 volts. Each generator is direct connected to a 300-H.P. tandem compound engine. The exhaust of these engines is piped to two motor-driven jet condensers.
The switching apparatus is placed on two galleries running longitudinally witli the building and built against the partition wall between the engine and boiler rooms. The upper gallery is used for feeder switches and compartments containing the group bus bars, to which the substation feeders are connected. On the gallery below are built the alternator oil switches, and, in the double floor of this gallery, runways are constructed with brick partitions for the main bus bars. The instrument panels are also placed on this gallery at a point near the centre of the building, and the exciter and auxiliary switchboards are located at either side, so as to be near the operator on the same gallery. A third gallery, built below these two galleries, is used for the accommodation of the feeder cables. The General Electric Form "H"' oil switch is used throughout, and, even under the most severe conditions in service, has
opened 11.000 volt circuits without trouble of any kind. The current from each alternator passes through a
500-ampere oil switch which is provided with an overload time-limit relay operating at the end of three seconds at about three times full load current. This oil switch is also provided with a reverse current time-limit relay which operates in three seconds at six-tenths full load current. From this oil switch connections are made to two
similar oil switches, without automatic relays, which are connected respectively to the two sets of main bus bars.
These bus bars consist of stranded copper cable of 1.000.000 circular mils section, insulated with 9/32 of an inch of rubber compound containing thirty per cent, fine Para. These cables are supported on porcelain insulators which are tested to 40,000 volts. Each cable is installed in a brick runway constructed under the floor of the switchboard gallery. A removable floor of two-inch slate is placed above these bus bars. The feeder cables for each substation are provided with a group bus bar placed on the upper switch gallery.
For supplying current to each group bus bar, two 800-ampere oil switches, without relays, are installed, each being connected to one of the two main bus bars. For each feeder cable, a 300-ampere oil switch is installed. This is provided with an overload time-limit relay set to operate at 300 amperes in about two seconds. Space is provided on the gallery for six feeder oil switches for each substation, these switches being all connected to the corresponding group bus bar. In all these oil switches each phase of the circuit is isolated in a brick compartment, each compartment containing two brass cylinders partially filled with oil. A copper rod runs through a stuffing box at the top of each cylinder and makes contact below the surface of the oil, so that, whenever a switch is opened, each phase is opened at two different points. An electric motor is employed to operate the switch, this motor being controlled by a miniature switch on the controlling board. The oil switch is very quick in its action, as the upward
or downward movement is accomplished by means of compression springs, while the motor serves to follow up and compress these springs for the next movement of the switch.
A 110-volt storage battery supplies current for the operation of the oil switch motors and the circuits to these motors are so arranged that the current is automatically cut off the motors at the end of each operation.
Two indicating lamps, placed on the operating board, are provided for each oil switch and are wired to contacts on the switch so that a red light indicates that the switch is closed, while a green light indicates the switch
open. The operating switches for controlling the alternator oil switches are placed on a controlling board and are
arranged with miniature bus bars which indicate to the operator, diagramatically, the connections of the circuits. A similar controlling board is provided for operating the feeder oil switches. On the instrument panels, each alternator is provided with three horizontal, edgewise ammeters, one voltmeter, one indicating wattmeter, one power factor indicator, and one recording wattmeter. A synchronism indicator is placed on the instrument board and connections are made to this indicator by means of synchronizing plugs and receptacles. In synchronizing an alternator with others already in operation, the indicator pointer moves either to the right or to the left, indicating thereby whether the alternator is running too fast or too slow. When the proper speed has been reached, the pointer is stationary. The oil switch is closed just before the pointer approaches the central position, for, at this time, the speed of the alternator which is about to go into service is approximately the same as the speed of the other machines and the alternations are also in synchronism. The use of this indicator greatly simplifies the
operation of synchronizing and is found to be preferable to the use of synchronizing lamps.
Each feeder cable is provided with three ammeters, one for each phase, placed on the instrument board of
the power station. For supplying 500-volt, direct current to the lights and auxiliary motors in the power station, three 800 kilowatt, six phase, rotary converters are installed. The coal and ash handling machinery, boiler feed pumps, exciter condensers, and crane are operated by current from these converters. The engine room is lighted by 1,500 sixteen candle-power incandescent lamps fastened to the columns and to the under side of the roof trusses. The lamps are of the 130-volt railway type, connected four in series. For the general illumination of the boiler room, arc lamps, supplied with 500-volt direct current, are provided, supplemented by incandescent lamps around the gauge glasses and boiler feed pumps.
The men employed in the operation of the power station may be classified as follows:
Superintendence and office force 14
Chemist 1
Men employed on electrical apparatus:
Switchboard attendants 9
Dynamo tenders and cleaners 18
Electrical repairmen 7
Summe: 34
Men employed on engines:
Steam engineers and assistant engineers 17
Oilers, wipers and oil system attendants 53
Machinists and helpers 20
Steam fitters and helpers 7
Blacksmith and helper 2
Summe: 99
Men employed in boiler room:
Boiler room engineers and attendants 20
Boilermaker, helper and cleaners 19
Stoker operators and assistants 57
Coal handling machinery attendants 13
Ash handling machinery attendants 10
Pump men 9
Mason and helper 2
Summe: 130
Laborers and foreman 16
Janitors and doormen 6
Total 300
In the operation of the power station the proportion of expense is divided as follows :
Operating expenses 92,25 %
Maintenance expenses 7,75 %
The operating expenses are divided as follows:
Coal, at $3.15 per gross ton 71 %
Labor and miscellaneous expenses 20,88 %
Water 7,7 %
Oil, waste, rags and grease 0,42 %
The following figures are given to show a comparison between the cost of operation during the summer and
winter months. Comparing the watt hours per ton-mile, it will be seen that during the winter months the
power required is about twenty-two per cent, greater than that required during the summer months, the difference being due almost entirely to the use of electric heaters on the cars:
Summer Months [Average for July, Aug., Sept. 1903] (Winter Months [Average for Jan., Febr. March]):
Average kWh (net) per day delivered 431.197 (595.996)
Average lbs. coal per kWh (net) 2,649 (2,610)
Average lbs. water per kWh (net) 23,21 (24,17)
Average lbs. water per lb. coal 9,00 (9,27)
Average kWh (net) per car mile 2,566 (3,35)
Average Wh (net) per ton mile 100,13 (122,68)
Average kW per car from maximum fifteen-minute readings 28,99 (39,04). |
| QUELLE | [New York electr. handbook (1904) 247-262] |
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