US1063511A - Steam-turbine and governing mechanism therefor. - Google Patents

Description

y L. GUBELIO & G. FORNER.

STEAM TURBINE AND GOVERNING MECHANISM THEREFOR. .hgfLIGATION FILED MAY 24, 1912.

1,063,5 1 1 Patented June 3, 1913.

49 secondagg Low seconda Pr essurevalvg Regulator. I

ressurevalve II I Z Witnesses: In Vent-OPS? Ludwi Cubelic,

' Geor For-ner- Their aflttornsy UNITED STATES rATEN T OFFICE.

- LUDWIG CITBELIC, OF CHABLQTTENBUBG, AND GEO BG FOBNER, QF BERLIN, GERMANY,

ASSIGNORS TO densest. ELECTRIC COMPANY, A cdReoRA'rIoN or NEW ORK STEAM-TURBINE AND s vaamse MECHANISM THEREFOR- Specification 0: Letters Fateut.

Patented J line 3,1913. 1

Application filed m 24, 1912. Serial No. ceases.

connected to an exhaust steam system and to which live steam canbe supplied, and t0 the governing mechanism for such turbines.

The object of the invention is to improve their construction and operation.

Our invention is described and illustrated as carried out in a multi-stage turbine having a high ressure inlet and an exhaust conduit of suitable construction. In addition to this inlet, conduits for low pressure steam are rovided whichcom'munica'te with stages of t e turbine operating atdifiere'nt pressures and having diflferent dischar e or fipw areas for steam. As an exam le 0 this feature, two such conduits ares own; Inthe turbine, the cross-sectional area of the working passage increases from the first to the last stage to accommodate the increased volume of steam as the pressure decreases,

To state the matter in other Words, the nozzle and bucket areas increase from the "inietflk ward the exhaust; Under normal or low pressurepperating conditions, steam is admitted By a conduit to a pressure stage having a working passage whose ieross-sectio'naliarea is designed to receive and pass the necessary amount of steamto drive the maximum rated load, When the volume of low; pressure steam supply materially de-- -creases, it follows that said cross-sectional area will be too great for said volume and hence the steam will notbe utilized to its best advantage To obviate this, the supply of low pressure'steam to the particular stage above specified is cut off and said steam is admitted by'atiothei conduit toangther pressure stage nearer the high pressure'mlet andv having a working assage of smaller crosssectional area which corresponds more closely to. the theoretical area forthe given volume of steam. If under these conditions the supply.is inadequate to drive the load,

sure, is admitted to the inlet or high pressure stage of the turbine and thelatterwill then operate under mixed pressure conditions. Care should be exercisedin selecting the stage to which low pressure steam is admitted under mixed pressure conditions to see that the pressure of the fluid therein is low enough so that such steam as is received therein from the high pressure source will" Y not tend to flow into the conduit supplying steam from the low pressure source.

The various conduits referred to above are provided with suitable valves under the control of a governing mechanism that is adapted to open and close them at the proper times, as will appear later. From the foregoing, a charactefi'stic feature of ourinvention will be seen toreside in the fact that, when operating under mixed pressure'conditions, the ow pressure or exhaust steam is supplied to a stage of the fur bipe having a smaller se LiOIl of workingpassage than when'the turbine is opera-tiiig solely 'under. low pressure conditions.

In the accompanying drawing, illustrating' one embodiment of the invention, Figure 1 is a diagrammatic view ofa mixed pressure turbine and the governing mechanism therefor, and Fig. 2 is a detail view of a part ofone of the regulators.

1 "indicates a multi-stage turbine of-anv suitable construction and comprising a high 'pressure and a low pressure portion. The

high pressure portion is idle except when the turbine is operating onthe mixed pressure plan. The turbine is provided with a casing 2 and diaphragms 3 for dividing it into stages. In each stage is a bucket wheel 4, and in line with each rowof buckets and supported by a diaphragm is a nozzle 5. The initial orhigh pressure. stage is rovided with a nozzle 6, usually slightly divergent, to which high pressure steam is admitted by the conduit 7. The first stage wheel is made larger in diameter than' the others because the steamvelocity is higher and hence requires'a higher bucket speed if the best results are to be obtained. The exhaust from the turbine passes by conduit 8 to a suitable condenser. ow pressure steam, such as the exhaust from an engine, turbine or other apparatus enters the turbine at some suitable stage, as for example the third in an eight stage machine, by the conduit 9. This is the'normal operating condition or -re1aconduit communicating with the first described later,

stage on the exhaust side of its wheel. This is the condition when the turbine is operating on the mixed pressure plan, the conduit -9 then being closed.

Steam is admitted to the turbine by three valves, which for convenience may be designated a main low pressure valve 11, a secondary low pressure valve 12 and a high pressure valve 13. The main low pressure valve 11 is actuated by the main hydraulic motor comprising a piston 14 and a cylinder 15. Said motor is controlled in its action by a regulator .16 comprising a casing and a piston valve 17. This re lator may for convenience be termed a secondary regulator because it is subject to the control of another regulator to be described later.

It may also be designated by the term ressure regulator because it is moved y a fiuid, such as oil, under pressure, as distinguished from being moved positively bymechanicalmeans. The secondary low pressure valve is actuated by the secondary motor .18 comprising a cylinder 19 and two movable pistons 20 and 21. To the cylinder space between the pistons. fluid under pressure is admitted by the pipe 22. This pressure varies with the variations in pressure of the low pressure source and may be transmitted directly or indirectly. Above the piston 20 is a spring 23 that tends to raise it, and under the piston 21 is a spring 24 that tends to raise it. The piston rod 25 of the main motor is connected to the piston rod 26 of the secondary motor by the lever 27. The movements of the secon ary motor are controlled .by the secondary or pressure regulator 16. Therefore, it will be seen that said regulator serves a'double purpose, i, e., regulating the action of both the low pressure valves 11 and 12. The high pressure valve 13 is actuated by a motor 28 comprising a cylinder 29 and a piston 30. Its piston rod 31 is connected by a lever 32 to the piston valve of the primary regulator, to be said lever being also connected by a pivot 33 to .the lever 27 which unites the piston rods of the low pressure valve motors. The high pressure valve motor is regulated in its movements by the pri-- mary regulator 34 comprising a ported Casing 3.5, and the piston valve 36 which is connected-by a rod 37 and pivot to the lmrizon-tal lever '32. The piston valve is provided with specially formed piston opposite ends to heads 38, best shown in Fig. 2, which have serrations or notches 39 at 1 their permit fluid under pressure, such as oil, to flow -parts have been illustrated by different kinds to the .motor 28 under the control of the speed governor, as will appear'later. The primary regulator also controls the passage of fluid under valve motor pressure, lator 16. v

40 indicates a speed governor which is. driven by the shaft 41. The latter may indicate the main shaft of the turbine or a shaft driven thereby. The essential condition is to have the governor responsive to changes in speed of the turbine. To the sliding collar of the governor is pivotally attached a governor lever 42, the other end of said lever being pivotally attached to the rod 37, or what is the same thing, to the horizontal lever 32. Attached to the governorlever is a balanced pilot valve. 43 contained in a ported casing 44. Fluid under pressure, such as oil, is admitted to the casing by the conduit 45. Fluid is exhausted from the valve casing in the usual way.

For convenience, different positions of the such as oil, to the secondary reguof lines to show different operating conditions. In full lines is shown the relation of parts for exhaust or low pressure operation; in dotted lines is shown the relation of parts for mixed pressure operation, and in broken and dot-ted lines is shown the relation of parts for high pressure operation. Owing to the small size of the drawing, no attempt has been made to show the exact position of the parts but only the characteristic or general relation.

Considering first the low pressure operation:- if the available amount of steam decreases, the load remaining the same. there Will be a decrease in the speed of the tur-' bine and the governor will move the pilot valve 43 downward. Since the special piston 38 of the regulator 34 is provided at its upper and lower ends with serrations or notches 39, Fig. 2. oil under pressure will flow from the pilot valve through the pipe 46 and notches 39 and pipe 47 into the cylinder 29 below its piston and start the high pressure valve 13 in operation. The upward movement of the piston 30 raises the left hand end of the lever 32 about its pivot 33 asa fulcrum. This movement of the lever moves the .piston valve 36 of the primary regulator 34 upward so that oil under pressure can freely enter the cylinder 29 below the piston and move the same upward until the governor connections return the pilot valve to its neutral position, the one shown. Simultaneously with the movement of the piston 38, the small pistons 48 are raised so that oil under pressure is admitted to the under side of the piston 49 of the regulator 16 and said piston is moved .upward against the-stress of the compression spring 50, located at the upper end. The result of this is to" permit oil to exhaust from the under plston 14 of the low pressure side of the and to admit oil under pres sure to the upper side of said piston 14,

causing the main low pressure valve'll to 9 close to a greater or less degree. The

amount that it closes should roughly approximate the decrease in said supply so as to hold the pressure substantially constant. Assuming that the low pressure supply of steam further decreases, the load remaining the same on the turbine, the secondary regulator valve 17 will continue its upward movement until the pipe 51 is placed in communication with the exhaust port 52 in the casing of said secondary regulator 16. This relieves the pressure above the piston 20 of the secondary low pressure valve motor and said valve 12 opens to a ;reater or less de-. gree under the action of the spring 24. At

or about the time the valve 12 is opening,

, valve 11 is closed by the action of its motor.

Referring now to the levers connected to the motor pistons and their action :-as the main low pressure valve 11 moves toward its seat, a. small movement only is imparted to the piston rod 37 of the primary regulator 34, because as the piston rod 25 moves downward the piston rod 26 of the secondary low pressure valve motor has moved upward, and hence the plvot 33 uniting thelerers 27 and 32 has only changed its position slightly. From this it will be seen that the under side of the piston 49 of the secondary regulator 16 is subjected to pressure from the regulator 34 during the mixed pressure operation and also during the high pressure operation. This relation is illustrated in broken and dotted lines. If the pressure or amount of the low pressure supply is increased, the speed of the turbine is increased, assuming the load to be constant for simplicity of description. The governor 40 then moves the pilot valve 43 upward and oil under pressure flows through the pipe 53, primary regulator 34 and pipe 54 to the upper side of the piston 30 of the high pressure valve motor, causing the valve 13 to move toward its closed position. By the downward movement of the valve 13, the rod 37 of the valve of the primary regulator is also moved down to its neutral position. This cuts off the piston 49 of the secondary regulator from the supply of oil under pressure and connects it to the exhaust through port 55. The spring 50 then moves the piston valve of the secondary regulator downward. This action permits oil under pressure to flow from the inlet port 5b to the upper side of the piston Z0 and cause the latter to move the secondary low pressure valve 12 toward its seat. As the rod 26 of the low pressure valve motor moves downward, it carries with it the right hand end of the lever 32 duel the connecting pivot 33. This movement of the lever 32 moves the valve rod 37 of the primary regulator downward slightly and with it the pilot valve 43. ThlS also places the lower side of piston let of the main low pressure valve 11 in communication with the pressure pipe 57 and its upper side with the exhaust through pipe 58, primary regulator 34 and pipe 53 and the valve opens. It

will thus be seen that just as soon as the 73 exhaust or low pressure steam has the necessary pressure or quantity to drive the load, a reconnection of the exhaust supply conduit 9 automatically takes place. If, with pure exhaust operation, the load on the turbine is reduced, the speed increases and the governor permits oil under pressure to flow through the pipe 53, notches 39 in piston 38 (Fig. 2) pipe 58 to. the upper side of piston 14, thereby closing the main low pressure valve 11 by the proper amount. This condition or relation of parts is indicated by the levers shown in full lines.

To recapitulate, the regulating mechanism is so devised that so long as the supply of low pressure steam is suttic-ient, the valves 12 and 13 remainolosed while the valve 11 regulates the admission of steam under the control of the speed governor. If, however, the speed falls below a certain predetermined limit and the valve 11 cannot supply the necessary amount of low pressure steam, then the regulating mechanism causes a change from low pressure to mixed pressura operation, closing valve 11- and openi .9.5 valves 12 and 13. As a result of this, suc low pressure steam as is available flows by the conduit 10 to the first, stage and is discharged by the nozzles or other devices to the second wheel. Since the discharge area of the working passage in this stage is smaller than that of any of the subsequent stages, it follows that a more favorable utilization of the steam will be obtained than would be the case if the exhaust steam always entered the turbine at the same place.

We have show two low pressure conduitsleading to different pressure stages in the turbine, and under ordinary conditions this is sufficient, but it is evident that a greater ,110 nu ber of connections can be made if desirgil. The governing mechanism can .also be applied to other types of turbines than the particular one illustrated and described herein.

In accordance with the provisions of the patent statutes, we have described the principle of operation of our invention, together with the apparatus which we now consider to represent the best embodiment thereof; .2120 x duits connected to the turbine at points intermediate the inlet and outlet where different pressures exist, and means responsive to an o crating condition of the turbine for cont olling the flow of low pressure fluid between the turbine and one or another of said conduits.

2. A turbine comprising relatively movable parts for extracting energy from an elastic fluid, and an exhaust outlet, in combination with conduits for supplying low pressure fluid to parts thereof ,which have different crosssectional areas of discharge, and means responsive to an operating condition ofthe turbine to change the admission from one of the conduits to another.

3. A turbine comprising high and low pressure portions, an inlet for the high pressure portion, an inlet for the low pressure portion, an exhaust, and a conduit which admits low pressure fluid to the high pressure portion under certain conditions.

4. A mixed pressure turbine, in combination with a conduit for supplying steam to a given stage for low pressure operation, a conduit for supplying low pressure steam to a stage of the turbine having a smaller crosssectional area of working passage than the one first named for mixed pressure operation, a conduit for admitting high pressure steam to a stage having a still smaller crosssectional area for mixed pressure operation, and means for controlling the conduits.

5. A mixed pressure turbine having a high pressure inlet and an exhaust outlet, in combination with low pressure conduits connected to regions of diflerent pressure therein, high and low pressure valves, and governing means organized and arranged to cause one of the low pressure valves to close and another to open when the supply of fluid from the low pressure source changes.

6. A mixed pressure turbine having a high pressure inlet and an exhaust outlet, in combination with low pressure conduits connected to regions of different pressure therein, high and low pressure valves, means for actuating the valves, and governing means organized-and arranged to cause one of the means to close a low pressure valve and open another as the supply of low pressure fluid changes.

7. A turbine having an inlet and an exhaust outlet, in combination with a high pressure valve, low pressure conduits connected to regions of difl'erent pressure in the turbine, valves for the conduits, a speed governor, a primary regulator controlled by the governor that directly controls the high pressure valve, and a secondary regulator forthe low pressure valves that is controlled by the primary regulator.

8. A turbine having an inlet and an exhaust outlet, in combination with a high pressure valve, low pressure conduits connected to regions of different pressure in the turbine, valves for the conduits, motors for actuating the valves, a speed governor, a primary regulator controlled by the governor which directly one of the valve motors, and a secondary regulator that controls another valve motor and is itself'controlled by the primary regulator.

9. A turbine having conduits admitting low pressure fluid thereto and an exhaust outlet, valves for the conduits, and a goerning mechanism organized and arranged to shut off the flow of fluid through one of the conduits and admit it by another when the pressure of the low.pressure source of supply decreases.

10. A turbine having conduits low pressurefluid thereto and an exhaust outlet, valves for the conduits, a speed governor, connections between the valves and the governor for modifying the action thereof, and a regulating means that is controlled by the governor and is also connected to said V-llPS.

11. A mixed pressure turbine having a high pressureinlet and an exhaust outlet with a working passage between, conduits that receive low pressure fluid from the same source and discharge it into regions in 'the turbine having different cross-sectional areasof working passage, valves for the inlet and the-low pressure conduits, and governing controls the action of I admitting mechanism arranged to open the valve in the low pressure conduit leading to the region having the smaller area of working passage when the high pressure valve is opened.

12. A multi-stage turbine that is provided with high and low pressure inlets and an ex haust outlet, and normally operates as a low pressure turbine, valve means for shifting the point of admission of the low pressure fluid from a low pressure stage to one of higher pressure as the fluid from the low pressure source decreases in amount, a valve for admitting live steam to the inlet to supplement the low pressure supply, a speed governor, and actuating means for the several valves that are controlled by the governor.

13. In culmination, a steam turbine divided into a plurality of stages, a conduitadmitting high pressure motive fluid to the turbine, conduits admitting low pressure motive fluid to stages of the turbine of different pressures, and valve mechanism for controlling the passage of fluidthrough said conduits.

14. In a multi-stage turbine operating on the mixed pressure plan, a conduit admitting high pressure fluid, low pressure fluid to sta es of difi'erent ressures, and valve means for opening the igh pressure conduit, closing one of the low pressure conduits and opening another for mixed pressure operation.

15. In combination, a multi-stage turbine operating on the mixed pressure inn and Comprising a stage that utilizes high pressure fluid only, one or more stages that nor-- mally utilize low pressure but which utilize high pressure fluid only when the turbine is operating on the mixed pressure plan, and stages that normally utilize low pressure fluid but which utilize both low and high pressure fluid when the turbine is" operating on the mixed pressure plan.

16. In combination, a multi-stag'e turbine operating on the mixed pressure plan and comprising a stage that utilizes high pressure fluid only, one or more stages that normally utilize low pressure but which utilize high pressure fluid only when the turbine is operating on the mixed pressure plan, stages that normally utilize low pressure fluid but which utilize both low and high pressure fluid when the turbine is operating on the mixed pressure plan, and valve means for connecting and disconnecting said stages with the sources of low and high pressure fluid.

17. In a multistage turbine operating on the mixed pressure plan, a condult admitting high pressure fluid, conduits admitting low pressure fluid to stages of difi'erent' pressures, valves controlling the passage of fluid through the high and low pressure conduits and means for simultaneously opening the high pressure conduit and closing one of the low pressure conduits and opening another for operating the turbine on the mixed pressure plan, and a governor for said valves.

In Witness whereof, we have hereunto set our hands this 4th day of May, 1912.

LUDVVIG CUBELIC. GEORG FORNER, \Vitnesses:

O'r'ro SCHMIDT, FRIEDRICH GANZERT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 6.?

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