US1072929A - Governing mechanism for turbines. - Google Patents

Description

w. L. '11 EMMET. I GOVERNING "MECHANISM FOR- TURBINES. APPLICATION FILED AUG.5, 1909. RENEWED FEB. 16,}912'.

1,072,929, Patented Sept. 9, 1913.

I 1 I 2 SH'EETSSHEE T 1.

lnverit orz William LREImmeL,

W. L. R.-BMMET. GOVERNING MECHANISM PORTDRBINES. APPLICATION FILED AUGQS, 1909. RENEWED FEB.16

Patented Sept. 9,1913.

2 SHEETS-SKEBT 2 Inventbr':

Witnesses:

WilliamLR.EImmet,

" UNITED; sTaTEs PATENT OFFICE.

R. EMMET, OF SCHENECTAIDY. NEW YORK. ASSIGNOR TO GENERAL 1 ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

GOVERNING MECHANISM ron TURBINES.

Specification of Letters Patent.

Patented Sept. 9. 1 913.

Application filed August 5, 1909, Serial No. 511,280. Itenewed February 16, 1912. Serial No. 677,963.

certain new and useful Improvements in Governing Mechanisms for Turbines, of

which the following is a specification.

Mv invention-relates to the governing of turbines which receive and are driven'by the exhaust steam from one or more high pressure reciprocating engines or other low pressure source of supply. In such an arrangement it is undesirable to permit the pressure of 'the'steam entering the turbine to faltbelow atmospheric pressure because the air admitted to the. system by leakage under such conditions will impair the vacuum due to the condenser which is connected to the turbine.

The objectof my inventionis to provide a. governing mechanism which will' automatically. regulate. or shutoff the supply of steam to the turbine when the pressure of its source ofsupply falls below atmospheric pressure and which will, upon the restoration of the pressure of the source above that of the atmosphere, automatically operate to restore normal operati or admit steam from said source to the t1 rbine. For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and 1 the claims appended thereto. In the accompanying drawings which illustrate one of the embodiments of my invention, Figural is a vie-win end elevation of a low pressure turbine equipped with my improved governingmechanism; Fig. 2 is anenlarged view of the valve mechanism and the motor for actuating it, and Fig. 3 is a sectional view of a pressureresponsive device which, under certain conditions, prevents the speed governor from operating.

I have shown my'inveution in connection with the governing mechanism for turbines patented to Oscar Junggien on June 23, 1908, Patent No. 891.342, since it is well adapted for the purpose. but my invention 9 is not limited to this particular type of gov- "erning mechanism as it is of wider applica tion.

1 indicates a"lowpressure turbine of the Curtis multi-stage type, although turbines 55 of other types may be governed by my imstem is attached at its upper cud to the lever proved mechanism. Exhaust steam from a high pressure reciprocating engine or. other source of low pressure supply is admitted to the turbine by'the conduit 2 and. after acting onthe stationary and movable bnck- -ets therein. passesto the condenser by the exhaust pipe 3. 4. indicates a speed governor which is-drivcn by the main shaft of the turbine. This govcrnormay be of any usual or well-known construction. The movements of the governor due to a change in speed of the turbine shaft are imparted to the governor lever 53 which is pivotcdat 6. Motion between the governor weights and the lever is imparted by the rod 7. The

admission of motive fluid'to the turbine is controlled by the butterfly or throttle valve 8 shown in dotted lines in Fig. 2. This valve or regulator is actuated by a fluid pressure motor 9.. The motor maybe actuated by steam, air or. liquid under pressure. The movements of the motor piston are controlled by the pilot or balanced piston valve 10 which is provided with a stem 11. This 12 and the latter is connected by the link 13 to the governor lever 5. The relation of the parts issuch that the free end of the lever 5 moves downward under conditions of increasing speed and upwardly under conditions of decreasing speed. The piston rod 14 of the motor is connected to a sliding cross-head 15. Attached to the cross-head is a link 16. whose outer end is attached to the actuator 17 shown in dotted lines. The actuator 17 is loosely mounted on the spindle 18 of the butterfly valve or regulator.

Keyed to the spindle 18 is a. clevis 19. Pivotally supported by the clevis is a locking device 20 which is provided with a projec- .tionor-finger 21 that enters a correspondingly shaped notch'in the actuator. The extension spring 22 normally holds these parts in engagement. So lon as the finger '21 is in engagement with the slot or notch in the actuator, the movements of the motor piston to and fro will act to move the butterfly valve or regulator about its axis in a manner to increase or decrease the amount of steam supplied to the turbine, depend ing upon which way the piston moves. Loosely-mounted on the hub of the clevisis an arm 23 to the free end of which is attached a weight 24'. This weight is normally restrained from acting by the latch I 26'is an arm 27 that is connected by-the rod speed oftheturbine under load changes 25 which is/'1 ma -a, at" QGT- ttiv S Qm G station- I ary were ttachedto' ---the-'sp1ndle I 28 L to? tar-=1 lever 2941;; The: lever} 29 normally stands in the positionshown andais actu ated by the emergency governor 30 when by a predetermined amount, as 10 per cent. for example. When the emergency. governor v operates, it releases the weight arm 23 and as the latter moves about its axis, it strikes a roller 31 on the locking device carried by the clevis, which action withdraws the pin or projection 21 from the actuator. Con- 15 tinned movement of the arm in a downward direction imparts a hammer-like blow to the clevis Whichswings the butterfly valve about [its axis and causes the same to close. If it' be desired to trip the valve. byhand it can be done by pulling the chain 32 which will trip thelatch 25 and permit the weigh't to fall in the manner just described in connec tion with the emergency speed governor. It will thus .be seen that the butterfly valve or regulator performs two functions, 7;. e., that of' a throttle valve to regulate the ad mission of steam to the turbine, and that of a stopor emergency valve to shut' down the turbine quickly by cutting ofi' its -supply of steam when the speed becomes excessivef.'

In order .to prevent overtra'v'el of the motor" or F hunting, an anti-hunting de vice is provided. .In the present illustra-- tion of my invention it comprises a bell 5 crank lever '35 which is supported by a pivot 36 carried by a fixed bracket or other support. One end-of thelever is'attached to. the cross-head by the pivot 37 while the other end is connected by the link 38 .to-.the horizontal lever'12.- The lever 12 is pivot ally'attached to the stem 11 of thepilot valve. Assuming that there is an increase. in speed of the turbine, the free end of the governor lever 5 is moved downwardly and witlrit-the rod 13 and right-hand end of lever 12, 'the pivot 39 acting as a fulcrum for said lever 12. This displaces the pilot valve and the motor piston starts moving toward the left, or in a direction to decrease 0 the opening of the Valve or'regulator' 8. Just as soonasthe piston starts moving Zhe cross-head moves the upper endof the bell-crank lever to the left which raises, the rod 38 and therefore the left-hand end of lever 12. While this latter operation is taking alacethepivot 40acts as a fulcrum for the everlQ. Asa result the pilot valve" 4 is ultimately restored to its initial or mid" position whereit closes the ports of the motor. In other words the" anti-hunting or follow-up device anticipates the action of the governor which can only change its direction of movement. when the speed changes. "'Without .a follow-up device the iwe il accomplished by making the diaphragm of sufiicient area to exert a terelativelyflarge a t ea assesses b andbelow the desiredispeetlfizi In operating alow pressure turbine con- "densing it is undesirable; to iullni t ,v steam to ,the -turbineat at pressure-below thatof 7 y I the atmosphere on, account of the fa ct'thatf the speed of the turbrne eficeeds 'th'e norlna-l air will leak-into the system through the joints in the low pressure pipingjand impair the; vacuum. To 'prevent ,thi s 'I: provide a pressure regulator which acts in a manner to prevent the .hutterflyvalve I or other type of governing .valve from .,admitting any steam through theconduiti2 solong as'the pressure at the' s ource of'supply is below atmosphere and which permits the g I sure conditions are restored." I V The pressure regulatormjthe present embodiment of my lnventlon' 1s constructed valve'to admit steam when the proper presas follows: Mounted on the guide for' the s5 upper end-of the pilotvalve of the'motor" or other support is a frame 41 which sup v ports a cupshaped casting 42. Covering 'the top of the casting is a diaphragm-43- which is held in place bye-ringer that is boltedtot e part 42; One side ofthje ,dia.-' phragm, injthls case the up'perfisfexppsed-td' atmospheric pressure andfthe other side," in

this case the under, is ekposedfto the pres. v sure.v of the steam exhausting f fromfthe engine or-thatin the exhaust headervyvhich supplies steam to the conduitl2; firms-communication is established by the pipe 45 which may be connected ia 't any convenient point in the piping system sodong it is between the point 'of exhaus'tfjof the. reciprocating engine and the butterfly valve, H The under side of the diaphragm;is-xattaclied to a rod 46 which passes through a suitablestu'fling box 47.. A compression springf'l-s acts on the-diaphragm against thepressure of the atmosphere and alsoassists in sup porting the weight of the rod a6v andlattached parts. The 'travel-of the rod. 4:6, due to"the actionof the diaphragmis sufficient when the latter is fully depressed'toamove' the pilot valve 10" to a position where 'it' will admit fiuidto the righthand end of the motor cylinder andi cause the piston f thereinrto move to the left andclose-the butterfly valve or regulatoli; In order :to accomplish this result the pressureregultii tor. must overcome the effect of the spee'd ,gove'rnor l on the pilot valvew-This can be force on the stem 11 Off":h WJPH t f-VHJV So long'as the. pressure conditions rem'airr-q sure onthe latter, Just asgisoong however as the pressure-of the; exhaust' from' the gine increases to that of'the atmosphere, the

admit an amount of steam suflicient to satisfy the load conditions of the turbine. It will thusbe seen that the butterfly valve or regulator has an additional function to the two already specified, 2'. e., that of shutting oil:- the supply of steam to the turbine without. however, disconnecting it from the actuating motor. As to the first two functions the regulator is responsive to speed changes and as to the last function,- to pressure changes. It will also be noted that the action of the emergency governor means on the butterfly valveor regulator is in no wa v allected by the diaphragm or pressure resp nsive means. The advantage of this resides in the. fact that under no condition can the turbine run away.

I have referred to the diaphragm as being subjected on one side to the pressure of the source of supply to the turbine and on the other side to atmospheric pressure. Under certain conditions I may subject the diae phragm to a pressure above that-of th atmospherc, which pressure acts in opposition to that of the source of-svpplv. uch an arrangement will be useful where. the pressure of the smll'CO of supply from the engine or 'other apparatus is above atmosphere ,and

yet it is desired to prevent steam belowthe predetermined pressure from entering the turbine.

In accordance with the provisions of the patent statutes. I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I dcsireto have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

. What I claim as new and desire to secure .byjLetters Patent of the United States is,

1. A governing mechanism for a turbine including a regulator and a speed governor for controlling the action of the regulator, with a means-responsive to the pressurecf the source of-supply of the turbine which when said pressure falls below a certain value overpowers the'governor and causes the regulator to close.

2. In a turbine governing mechanism, the combination 'of a regulator, a. governor means for varying the position of the regulator in accordance' with 'load changes on the turbine, at second governor 'means for diseonnectingthe first'from the regulator and closing the latter suddenly under conditions of excess speed, and a pressure responsive device which under certain conditions assumes control of the regulator to the exclusion of the first governor means.

3. In a governing mechanism. the combination of a regulator, a motor for actuating it, a controller for the motor. a speed governor that actuates the controller. and a pressure responsive means which under certain conditions ovcrpowcrs the governor and acting on the controller causes the motor to move the regulator.

4. In a governing mechanism. the conr bination of a regulator. a means including a speed governor for actuating the regulator in response to .load changes. and a means subjected to the pressure of the source of supply on one side and to a predetermined pressure on the other. which under certain pressure conditions overpowcrs the governor and moves the regulator.

5. In a governing mechanism. the combination of a regulator. a means including a speed governor for actuating the regulator in response to load changes, a diaphragm subjected on one side to atmospheric pressure and on the other side to that of the source of-supply of the apparatus being governed, and a means for transmitting the motion of the diaphragm to and overpowering the governor.

(3. In a governing mechanism. the combination of a regulator, a motor for operating the regulator, a pilot'valve for the motor, a speed governor controlling the action of the pilot valve under normal. conditions, and a pressure responsive device which under certain COIIdltIOIlS ttIkES the control of the pilot valve away from the governorand causes it to admit fluid to the motor in a direction to close the regulator.

T. In a governing mechanism, the combination of a regulator, a motor for operating the regulator, a pilot valve for the motor, a. speed governor controlling the action of the pilot valve under normal conditions, a diaphragm exposed on one side to apredetermined pressure and on the other side to that of the source of supply, and a means for transmitting the movements of the diaphragm to the pilot valve;

8. In a governing mechanism, the combination of a regulator, a speed governor which normally controls the action of the regulator, a second speed governor which. .under abnormal speed conditions closes the valve suddenly and this irrespective. of the first goveinor, and a means responsive toabnormal pressure conditions whi'clrcloses the regulator and holds it closed until the predetermined. pressure conditions are reestablished.

. 9. A governing mechanism for a turbine utilizing low-pressure steam from a suitable source of supply whichincludes a. regulator ,Imeansand aspeed governormechanism for controllingthe"'action of the regulator .vmeal'is, with a 1 device responsive" to' the pressure of the steam, and means for transmit- 1 sureio f' the {low-pressure steam" from sa-id- 1: ting tl'leiac tion of the device to affect the governor mechanism sothat when the pressource of supply falls below a'predetermined value said device assumes. control of the gregulator'means to'the exclusion of the speed '21 governormechanism.

110 In a governing mechanism for turbines' utilizing steam'fi'om a suitable source of supply, .the combination of a. valve for 15:

fegulat'ing the-ad-n'iission of steam to the tur- .'bine,'a speed governor, a motor for operating the valve, a pilot valve for the motor,

a leverpivotally connected intermediate its I 1 ends. tothe stem ofthepilot valve, a con- 10f the lever,.a connection between the other end ofthe leverand the movable member of nction between the governor and one endthe motor, and :t'device responsive to the pressure of the {steam from said supply with-said means to'modifv-its action on the valve mechamsm when, the pressure falls .below a predetermined value, Y

which moves -the pivotal: eonneot-ion between 25 tor regulating the admission ofsteain-from' the source to the turbine, speed responsive means for controlling the valve mechanism, 35

and a device responsive to the pressure of steam supply that "is normally out of engagelnent with the speed responsive means but is automatically movedinto engagement 'In'witness whereof, I have hereunto set my hand this 3rd day of August, 1909.

. WILLIAM L. R. "EMMETQ- lVitnesses:-- i

BENJAMIN B. HULL, MARGARET E. WOOLLEY.

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