US1799361A - Governing mechanism - Google Patents

Description

April 1931 w. B. FLANDERS 1,799,361

GOVERNI NG MECHAN I SM Filed Feb. 21, 1930 A WITNjSS INVENTOR Q4 Warren B. Flanders ATTORNEY Patented Apr. 7, 1931 UNITED STATES PATENT OFFICE WARREN B. FLANDEBS, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC 6; IvIAIl'UFIiCTURING COMPANY, A CORPOBA'IIQN OF PENNSYL- VANIA GOVERNING MECHANISM Application filed February 21, 1920.

35 or no load, for example, when operated as running standby for water power, must be kept at a safe temperature, that is, maintained at approximately the operating temperature, in order to be capable of quickly taking load.

In accordance with my invention, I provide a relatively small valve for admitting an amount of motive fluid just sufficient to maintain the turbine at a proper temperature, and I provide a governing mechanism which is set to close the valve when the speed of the turbine exceeds the normal range of speed of the power system to which the turbine is connected, and which, therefore, maintains the small valve fully open throughout the normal range of speed.

The above and other objects are effected by my invention, as will be apparent from the following description and claims, taken in connection with the accompanying drawings forming a part of this application, in which:

Fig. 1 is a diagrammatic view of a turbine' and generator unit having the governing mechanism applied thereto; and,

Fig. 2 is a sectional view showing the small admission valve and the main admission valve. 7

Referring now to the drawing more in detail, I show a turbine 10 connected. to a generator 11. The generator 11 is connected through a circuit breaker 12, to a power system 12, to which it is adapted to deliver electric power. The speed of the unit is con trolled by the frequency of the alternating Serial N'o. 430,314.

current in the power system 12, the generator 11 being preferably a synchronous generator. The turbine and generator unit 10-11 is intended to be operated a substantial portion of time as standby, that is, to be kept running without developing power, but to be ready instantaneously to take load.

In order to maintain proper and safe temperature conditions of the turbine while running standby, that is, to avoid excessive heating of the blading by friction with fluid in the casing and to maintain all parts of the turbine at approximately the operating temperature so as to avoid distortion when taking load, I provide a relatively small flow of motive fluid through the turbine while it is running standby.

Referring to Fig. 2, I show a main admission valve 13, controlling the admission of motive fluid to a group of nozzles 14. At 15, I show a relatively small valve which controls the admission of steam to a smaller group of nozzles, for example, the single nozzle 16. The valve 15 and the nozzle 16 are of such capacity as to admit a quantity of steam just suflicient to maintain the turbine at approximately its operating temperature. The nozzle 16 is preferably designed for an expansion ratio providing maximum efliciency when operating alone.

I? or operating the valves 13 and 15, I prole a governor mechanism indicated generby the numeral 17. I prefer to use a pressure governor, including a pump 18, having an impeller 19 mounted on the shaft of the turbine and providing a fluid pressure varying as the square of the speed of the turbine. The fluid pressure developed by the pump is conveyed through a conduit 20 to motor devices 21 and 22, which operate the valves 13 and 15, respectively. 7

Each motor'device comprises a cylinder 23 and a piston 24 disposed in the cylinder. The'piston 24 is connected to the valve 13 by means of a rod or stem 25, and it is biased in the direction for opening the valve by a spring 96 disposed between the piston and a spring holding member 27. The initial force or setting ot the spring may be varied by moving the spring holding member 27, for which purpose a hand wheel 28 is provided. The conduit 20 communicates with each cylinder 23 i on that side of the piston on which it acts to bias the piston in the direction for closing 5 the valve and in opposition to the force of the spring 26.

The motor device 21 i s so designed and aded that when the speed of the turbine is or above the minimum speed of the normal speed range, the fluid pressure developed by the pump 18 is suilicient to overcome the force of the spring 2'? and to "fully close the valve 13, and o begin opening this valve as soon as the pro ure drops below that corresponding to said minimum speed, or to a lower speed. The motor device 22, on the other hand, is

i d that the fluid pressure developed r r elow the maximum speed, ange of operating speed, is to overcome the force of the spring tin is valve 15 to be wide e 15 when the pres-- a spending to said peed, or to a somewhat higher speed.

The ope ation of the above described mechanism will now be apparent: Vii-thin the normal range of operating speed oi the power system 12, the fluit presso sure developed by the pump 18 is such as to eltect lete closing 01" the main valve 13 and c -'e odenin of the small valve 15.

An amount or" motive fluid just suliicient to maintain the turbine at a safe temperature is admitted. Should the speed of the turbine become excessive, however, due to any cause such as opening'o-f th circuit breaker 12, the flu d pressure developed by the pump 18 e1:- ceeds the pressure corresponding to the maximum normal speed and begins to'etlect closing of small valve 15, thereby preventing e2;- cessive speed of the turbine.

Should the speed of the turbine decrease below the minimum normal speed, the governing mechanism begins to open the main valve 13 of the turbine and the generator unit then begins to take a portion or" the load on the system 12.

From the above description, it will be seen that I have provided a governing mechanism whereby a quantity of steam just suflicient to maintain the turbine at a proper temperature is admitted during normal variations in speed, and whereby said admission may be restricted to prevent excessive speed of the turset forth in the appended claims.

While I have shown my invention in but What I claim is: I

1. The combination with a prime mover normally running standby and connected with another source of power which normally controls the speed thereof, of means for controlling the admission of motive fluid to the prime mover including a valve adapted to admit a relatively small amount of motive fluid for maintaining the prime mover at approximately its operating temperature while running standby, a second valve adapted to acmit a larger amount of motive fluid for carrying load, and means responsive to the speed of the prime mover for maintaining the first valve open and the second valve closed throughout a predetermined range of normal speed, said means acting to close the first valve in response to predetermined speed above said range and to open the second valve in response to predetermined speed below said range.

:2. The combination with a turbine and generator unit connected to a power system which normally controls the speed of the unit, said unit normally running standby, of means for controlling the admission of motive fluid to the turbine comprising a valve adapted to admit relatively small amount 01" motive fluid for maintaining the turbine at approximately its operating temperature while running standby, a second valve adapted to admit a larger amount of motive iiuid for carrying load, and means responsive to the speed oi the unit formaintaining the first valve substantially ll open and the second valve fully closed throughout a predetermined range or normal sneed, said means to close the first valve in response to predetermined speed above said range and to open the second valve in respon o to prece- VJARREN B. *FLANDEBS.

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