US1792255A

US1792255A - Governing mechanism for turbine-driven sets

Info

Publication number: US1792255A
Application number: US400984A
Authority: US
Inventors: Reginald G Standerwick
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1929-10-19
Filing date: 1929-10-19
Publication date: 1931-02-10
Anticipated expiration: 1948-02-10
Also published as: GB366470A

Description

Feb. 10, 1931. R. G. STANDERWICK L792255 GOVERNING MECHANISM FOR TURBINE DRIVEN SETS Filed Oct. 19, 1929 Invento: Rec'vn ald G .Stand ePwLck.

'Patented Feb, 1o,l 1931 v` UNET rin-Grimm) G. `STANDnnWIoK,*er`ManetEncan,A raessaonusnrtrs,"iissrencn'fro GENERAL ntncrnic contaminan coRPonA'rron or NEWYQRK l Yetoviilnvine ranolhnrsia non 'r'unnnnnavnnsnrs Application fiieactoifls, 1929." sei-iai No. cass/1Q' v.The present inventionA relates to turbine driven sets, and especially to governing means for such sets.

The object of my invention"iskto'iprovide.V

an improved governing mechanism Vfor such sets, and for a consideration of what I believe to be novel and my invention, attention is directed to the VaccompanyingEdescription andthe claims appended thereto;

1c' Y One application Vof my invention is in conv nectlon with turbine driven centrifugal compressors, wherein the speed is governed by an operatingcondition other .thanthe speed of f the set, for example, the volumeiofluid supplied'to the compressor, the suction pressure,'

or the discharge pressure, and also by the y Y supply actuating iiuid for the' control mechtion .I vhave elected to illustrate specilically.V

' speed of the set, and in the present applicathis application of my invention. lIt Visto be' 2c understood,however, that this is only by Way of-.eXample and that my invention is not limited thereto "except wherek specifically so stated in the claims. In thedrawing; the-*figure is av diagram- 'matic' view of a turbine driven centrifugalk compressor provided. with a'governing mechanism embodying my'invention. f Y y vReferring to the drawing, 1'indicates"an elastic fluid turbine having an inlet conduit 2 andan exhaust conduit 3and 4 indicates a centrifugal compressor having an-i'nlet conduitI 5 and a discharge conduit 6.-

tur-vr bine compressor'I set is shown only diagrammatically and is to be taken as indicating any suitable type of turbine and 'of centrifugal compressor. Y L

In conduit 2 is Aa'valve means 7 forv controlling the admission fof elasticiuid 'to the. Valve means 7 has its stem 8 con-l nectfedto a piston 9 located inta cylinder 10;- the piston and-cylinder'ormingia'V part of ai turbine.

duid actuated motor; 11 is aspring lwhich acts on `piston 9r in Va direction 'to move itY downward to effect -closing of valvemeans 7 l f `Connected to the upper side ofgpiston 9 is a stem 12'which at-.itsl upper eiid"is;pivotally connected to a floating lever 13; Connected 'to Cylinder iobe'neau 'piston 9 Visa pipe 14f which leads toitheicasing: 15 of a pilot valve' structure:whiclcontrolsthe admission of abr iioating. lever 4:3;y

tuatino' fluid to and from the space. beneath I z: piston 95 In pilot Avalveing and is provided witha'nopening 17 which' vthrough a 'vertical driving ",shaftv26.-y Shaft.

2G drives also'a pump 27 which is utilized to anism. Pump 27 may be ot any suitable type,j

. or'example,` itmay be a gear pump." Its* suc'-v tion inlet `isi indicated at l.28 .and its [discharge conduit isindicated at 29,-the'latterfbeing provided with a suitable relief valve 29a. 'Y It 'islocated in a tankr30 whichrepresents the oily tank `of thel turbine. Pump '27 VVmay be,"

for examplmthe pump which supplieslubri-- cant to the turbine and compressor bearings. f Connected to discharge lpipe 29 is a pipe 31' I valve sleevelQy -i I IPilot valve sleeve- 16 is'pivotally connected .K b'yia link" '32'Y to vlever v13'. The right-.hand yend of lever 13 is p'ivotally connected'to a rod the lower end of which is connected to a pisfr ton 34 located in a cylinder`l35. 1n cylinder 35 is a springi36 which acts in a direction to' 1 force piston A'34: downward toward 'the bottom ofcylinder V35. Piston 34'au'd cylinder' `'form a part of a fluid actuatedinotor to which:

actuating fluid is supplied by alpipeV 37, the flow of luidrto pipe37`being controlled by a pilot valve structure comprising a pilot valve casing 38 in 4which'islocated'tlie casing-'15 is a fbushing or y sleeve-316 Whichis 'adapted to'slide in the cas"` y Y communicates with p1pe14,a`n admission portA y which leads tothe Vinlet port 18ct the'pilot pilot valves y? Y 39 and40. Piloty valve 39 controls the admis# 'i sion of'actuating fluid supplied through a pipe 41, and pilot valve @controls t'lieldis; chargev of actuating fluid from' pipe 37 P ilotfv andare pivotally connected by a linlg 2 to a yvalves 39 and L10 are connected to each other 'lhe'iriglitdiand Iend ci vice is shown as being'av suction re`spons'ive-; device, the specific embodiment of the invention illustrated being one wherein the turbineV 1,

" is controlled in terms of the suctionpressure':

The device is shown'as comprisinga casing in which is located an inverted bell 51, the

Vedges of which areY located in .an annular chamber 52 in which is a .Sealing liquid 53. The un'der side of the be'll is subjected' to the pressure in .the suction'condnit 5 a pipe 54.

The outer side of the bell is subjected to atv mosphericr pressure through the open-ing 55.

" The bell'51' isconne'cted bv a stem 56 to the left-hand end-of lever 48. lllhewidtli lof regnlationof the suctionrespon'sive device, that is, the pressurechangefor change in load as controlled by the pressure responsive device,

l isy cont-rolled by an adjustable spring 57 located-between lever'48and an arm 48a.V By

moving spring 57 toward the fulcrum point.. of lever48 the widthfof regulation is narrowed, andy by moving it vfrom the Vfulcrum point `the width ot regulation is broadL ened.y The springmay be adjusted by means ofthe `openings shown in lever 48 and arm 48a. At 58 is an-adjustable weight for setting thefl'evice for'the desired: suction4 pressure.

vThe operation i'sas'follows: i ,ssume that the turbine is running an( thatthe desired suction pressure obtains in'v theconduit 5. Under' these circumstances, the various parts' of ythe control mechanism` willbe in equilibrium, occupying the positions shown in the drawing. The admission of elastic iluid to 'the turbine is controlled directly by speed governor 23', which" tends to hold the turbine at a certain speed. It'

the speed tends to increase, due'` to, for-example, variations 1n driving force caused' by Vvariations in the initial pressure of the elastic fluid, variations in back pressure o'r-,variations in extraction in the case of an estrac tion turbine, speed governor 23 willl move" pilot valves 20 and 21 downward slightly, whereupon pilot valve 21 will uncover somewhat the discharge port 19, permitting fluid pressure to escape from. beneath pi'ston9.A

Spring 11 will thereupon force Vpiston 9down` ward closing somewhat the valve means 7. Then piston 9 moves--downwardiit carries with it the lefthand end oifloating lever- ,13,

therebylowering-pilot valvesl-ee've 16 to' bring it to a position wherein port 19 is' again covered by thel pilot valve 21, lever 13 turning on stem 3821s apivot.; This forms a'usua-l Atia'llyconstant.'rV v i Assume now that V; the Y suction pressure nr conduit '5i1nc`reases`, which'means1 that zvalvearrangement-of follow up connection for the fluid actuated motor. If the speed tends to decrease, pilot valves 20 and 21 are moved upward slightly, the pilot valve 20 uncoverf ingadmission port 18, whereby fluid pressure is admitted through pipe 14 to cylinder V10 beneath Vpiston 9, raising' the' piston somewhatV and effecting opening movement of valve means, 7 to increase the admission of elastic'iuid to the' turbine. When' piston 9 moves upward, it Yturns. lever -18in a direction to lift pilot valve-r sleeve 16 to a position,whereinfthe admission port 18 is again. covered by the. pilot valve 20, thus restoring the Vparts totheir former positions; r ItI 1 will thus; be seen-@that` the speed governor is inimmediaiecontrol oii-thervalve v means 7 and tends to hold-thespeedsubstam'f means mustibefopenedl somewhatzto increase thel speedftheyturbineisog to bring the suction pressure baciato lthe desired value;

The increased suctionjprssme facting on' the and 'throughllink' 47 lowering the letfhandf end `ofv lever 43,Y and hence .thev pilot' valves'` 395and140. When

pilotvalves

39 and 40 are lowered, pilot valvek 40 uncovers,l the: discharge-pont in pilotlvaflfve casing 38,' permit# ting` actuating fluid' to escape from thet under side of p'is'tonA 34.11 4Spring Blthereupon moves piston 34 'down'ward,L loweringilthev righthand endsrofl levers v13 and* 45. `lhelowering of the right-hand endI of lever 18 moves pilot valve sleeve 16 downward, thus bring admissiony portV 18 outvr of' linev with piloti. valve' 20 so that f actuating fluid `is admitted' through j pipe'14 to the cy'linderl()l of the fluidv actuatedA motor,` Piston 9: is Athereupon moved'g upward' against theaction of spring 11, 'opening the valvemeans7 whereby the speed of the turbinexwillbe increased: The increasedv turbinespeed causes "the'weights of speed' governor 2Bft move outward, thereby lowering 'thepilot 'valves`f20 and' 21 to bring them again into linewitli ports-18and 19; The turbine now operates'at the increased speed, which increased speed is such as to restore the' suction pressure torthe desired value. VWhen vpiston 9 :movesv upward it lifts thefleftlhand 'end'.oflever 131 the saine turning on stein 33" als a pivot. :"lfhi'sy moveliient raises' slightly the prlot valve'sl'eevej 16 in ai direction'to restore 'itto'i-ts'f former position wherein port 18`is-covered by the' pilot'valve 20. However, the travel-:of piston 9is1sosmallconpared to thetr'avel of 'piston 34 that this' restoring a'c- .tion is negligible'. The turning ofA lever 45' fon its pivot. with the downward movement ofl piston 34, raises the right-hand end yof `lever'.'4 8,'V 'thereby restoring pilot valves and f 40 .totheir former positions,l wherein meantpilot valve covers the-discharge port of pilot valve casing 3 8. In case the suction pressure varies in the opposite direction, a similar operation occurs except in the opposite sense, the valvemeans 7 being then moved Vtoward closed position to decrease the speed of turbine l and vbring the suction pressure .back to its normal value.

lVitli the above described arrangement, it

u will be seen that the suction responsive clevice does not act directly on the valve means of the turbine, but acts on it indirectly through the intermediary of the pilot valve which is controlled by the'speed governor.

In other words, thesuction responsive de.- vice operates to varyV the setting of the pilot valve sleeve 16, and for every position of the pilot valve sleeve within its range of move,- ment, there is a definite corresponding Vturbine speed. Valve means 7 is ythus always under the direct control of its-speedY governor. Heretofordin connection with apparatus l of this type, it has been the practice in regulating it to have the ysuction responsive deviceact directly on the valve gear, the speed governor being Vset fora speed higher than normal speed and serving as apre-emergency Y governor, or to have the suction responsive device act` on the synchronizing speed ad- *l justing spring of the governor; Byjmyiinproved construction, wherein the suctionlref sponsive device acts on a pilot valve sleeve, I obtain improved operating lcharacteristics in that the governor is more sensitive, ac-

'1 curate and prompt.. Movement of the pilot ly on the pilot valve sleeve, the governing ismore stable because a quicker' action is olo- In addition vto the foregoing, im-y portant results are obtained also because distained.

turbances in speed which may be caused by variations in initial pressure of the actuat-k ing fluid, variations in back pressure on the turbine, or, in the case of extraction turbines, variations in amounts of extracted steam, are arrested immediately by the action of the speed governor rather than allowing the speed to wanderand disturb the suction pressure at the intake of the compressor. If the valve means is moved directly by the action` of the suction governor or similar device, a tendency for unstable action is set up, due to the fact that considerable time must necessarily elapse for theY suction pressure to change materially, and especially is this true Where, as is usually the case, the capacity 'f of the `suction line isvery great.

patent statutes, ,f I have, described the principle oi; operation of' my invention, together ith the.. apparatus whichglnow consider to represent the best embedimentithereofbut paratus shown is only illustrative and, that the -invention.may bevca-rried; o uti by ..other by' Letters forpositioning the valve means, apilot valve claim as newandidesire to; secure v Patentof the United States t .f fl-recombination a.turbine.drie/eni-Set,V Valvefmeans- Controlling vthe adm'ssoaof Velastic Vfluid to the set, a fluid actuated motorV structure "compris'ing'a' casingffa sleeve 'in' the casing, and a pilot valve in the sleeve, said sleevehaving openings controlled by thejpilot valve for controlling the supply of actuating fluid to said motor, a speed governor connected tosaid pilot valve, and meansjcone trolled by an operating conditionofsaidset Y other than 'its-speed forpositioning said pilot valve sleeve to vary the speed ofthe set, theV set being normally under control vofsaid speed 2. In combination,a turbine driven set valve `means controlling the admission ofk elastic fluid to the set, a fluid actuated motor for positioning the valve means, a pilot-valve structure comprising a casing, a sleeve in the' casing, and a pilot valvein the sleeve, said sleeve having openings controlled by the pilot valve for controlling-the supply ofactuating fluid to said motor, a lspeed governor connected to said pilot valve, a fluid actuated motor connected to saidsleeve, and. a pilot valve controlled by an operatingcondition of the set other Vthan its speed `for controlling the admission of actuating fluid -to said last named liuidfactuated motor for positioning'y said sleeve to vary the speed of the set, the'set being normally underv control of said speed governor. l

3. In combination, a turbine driven set, valvelmeans controllingV the admission of elastic fluid to the set,a fluid actuated motor for positioning the valve means, a pilot-valve structure comprising a casing, a sleeve in the casing, and a -pilotvalve in the sleeve, said` sleeve having openings controlled by the pilot valve for controlling the supply of actuating fluid to said motor, va speed governor connected to said pilot valve, f and means con- -Vtrolled by a pressure appurtenant to an operating condition of the' driven machine'for po-' izo sitioning said pilot valve sleeve to vary thel i kspeed of the set, the set being normally under:

control of said speed governor. f

4. v'In combination, a turbine .driven set, valve means, controlling thel admission of elastic fluid to the set, a lluid actuated motor v`for positioningthe valve means, a pilot-valve lstructure comprising 'oppositely" movable members having openings Which control the lasrv isov , owof actuating u'df to sa'dfui'd' actuated mOtOLa-speedgOVernOr connected' to one of said .anembes 4'to' move *it `n response lto changes in speed-forleeoting adjustment ofk sadvalve means,-arndmeans controlled by an operating-condition offfthe set other than its speed connected to theot-her fof said `menioers tof-move` it response 'to cl-langesnsad operating condition to effect adjustment ofsad Km' valve means,*the'set`^beng normally `under Y