US1091345A

US1091345A - Mixed-pressure turbine.

Info

Publication number: US1091345A
Application number: US78397713A
Authority: US
Inventors: Oscar Junggren
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1913-08-09
Filing date: 1913-08-09
Publication date: 1914-03-24
Anticipated expiration: 1931-03-24

Description

MIXES? liz fi s s n fi w t f lm: 1,091,345 Filed Aug. 9, 1913 PATENTED MAR. 24, 1914.

s Sheets-Sheet 1 Witnesses Inventor-2 Hi .7 T oeg Oscar- Ju Pen 9 0/ I Filed Aug. 9 1913 3 Sheets-Sheet 2- Witnesses:

I 17 His q tt r-neg.

.e r i nu em We s. 09 b JUNGGREN MIXED PRESSURE TURBINE ED MAR. 24, 1 914 Filed Aug 9 1915 PATENT s Sheets-She et 5 UNITED STATES PATEn'r oFF-icE.

oscA UNeenEn, or SCHENECTADY, NEW YORK, ASSIGNOR To GENERAL ELE'ciEic COMPANY, A coaromrron or NEwYonxf. v,

MixEn-PnEssUEE TURBINE.

' supply is sufficient to carry the load, any deficiency inthis respect bein made u by high pressure steam' admitteg after the low pressure throttle valve has become wide I open. In such systems it-is, of course, desirable to have the highest efficiency possible when the unit is run with low pressure steam as wellas whenit is supplied with high pressure fluid. Heretofore it has. been-- proposed for the sake of simplicity to use a portion of the. first bucket wheel for high pressuresteam and the remainder' for low pressure. While this is cheaper, it is not the most economical arrangementyas the buckets are designed necessarily for low 'pres sure operation and are not so efficient when supplied with high pressure steam. An-

other arrangement is to have one of the wheels equipped .with buckets properly designed for high pressure steam only, and allow this wheel to run idle when the machine is operating under low pressure. But this wheel is a detriment at such times owing to the rotation losses it entails due to rotating it in the low pressure steam. An-

other suggestion is'to make the high pressure part of the .unit quite independent 'o fthe low pressure part, but connect the high pressure stage with the condenser by a valve which opens automatically when the high pressure steam is. shut ofi, so that when the hi h pressureepd is running idle the wheel wil rotate in a vacuum with -minimum losses. The two parts of the turbine are conn'ected by a pass e controlledby-an automatic valvewhic opens when the high pressure-steam is admitted to'its stage, and permits said steam to. exhaust' nto the low pressure end of the turbine.

invention relates to' a mixed pressure turbine ofthis latte'r'class', biitI have sim- .p1i-fied theconstruction made the "machine more compact. LBI'OVISIOTI is made forv specification of Letters latent. Application filed August 9,

Patented Mar. 24, 1914.

Seria1No. veaerr.

keeping the high pressure stage ,o pen 'at all times to the condenser vacuumybut throu 11 a restricted passage which cuts down lea age losses when the high pressure end is operating provide a special set ofnozzles for receiving the exhaust from the high pressure end of themachine and directing it upon the buckets of-the first.stage ldw pressure wheels. I also. arrange for admitting the low pressure steam to these special nozzles in case of an extraordinary overload.

Two or'more automatic valves are used in the passagewhich conveys the exhaust from the high pressure wheel to the special low .p'ressurenozzles, andthese valves arearranged'to operate in parallel. In the accompanying drawings, Figure 1 is an end elevation,- partly in section, of a mixed pressure turbine embodying my improvements; Fig. 2 is a sect onal end eleivation' f taken on the line 2 2' o-f Fig. 3; F g.3 s a vertical longitudinal section,'and .Fig. 4 is an enlarged sectional View of one of the automatic 'check valves controlling the passage between the higlr pressure end and the low-pressure end of the unit..

The turbine illustrated is a horizontal I machine ofthe Curtis type. The shaft 1 passes through the casing 2 and is journaled in suitable pillow blocks 3, Fig. 3. A diaphragm 4 shuts ofl" one end of the casing from the downwardlyopening condenser exhaust conduit 5, forming a stage chamber for one or more bucket wheels 6, mounted on the shaft 1.1 Only one stage and one wheel are shown in thedrawingt'but it will be readily understood that the number of such stages and wheels is immaterial. High pressure steam is' supplied to this wheel by suitable nozzles 7\opening fromra steam chest 8 connected with the steam main 9, Fig. 1 The nozzles are controlled byJnoz- 'zle valves l 0,'which are operated by any suitable control mechanism. I have illustrated a familiar construct-ion, inpwh'ich each valve islifted byalever 11, operated Qby a cain on ashaft 12, which is geared to' arack 13 actuated a hydraulicmotor '14.

The pilot valve of;this motor isfcontrolled by the speed-responsive governor 15. .The opening in the'diaphragm 4: through which the shaft 1 passes is not packed, and

affords a restricted opening throughwhich' the condenser vacuum may work into the high pressurestage when the-high pressure a plurality .of such wheels. The low 24 being low pressure steam.

steam is shut off. When the high pressure steam is being used in this stage, a'small portion of the exhaust from the wheel 6 will escape aroundthe shaft directly into the condenser, but theamount of such leakage steam will not be serious owing to the re- 'stricted nature of the annular opening around the shaft. Mounted upon the shaft 1', also, are the low pressure bucket wheels 16, preferably each in its own stage, the four which are shown being merely illustrative of P sure steam is applied to .the first of these wheels through nozzles 1 7, Fig.3, which-receive steam fromthe'nearly annular chamber 18, Figs. 2 and 3, concentric 'with the shaft and communicating directly with the low pressure steamniain 19.. A butterfly T throttle valve 20 in said-main regulates the supply of low pressure steam and is in its .turn controlled by the motor 14: through the rack-2l',-Fi'g;.1, segment gear 22 and opera tive connditionbetween said gearand the spindle of said valve. The arrangement is such that the motor opensthe low pressure throttle valve wide, before be inning to open the high pressure nozzle va ves. -A handoperated double-beat stop valve 23 enables the attendant to shut off the low pressure steam at will. The last of the low pressure wheels exhausts into the condenser exhaust conduit 5.

In addition to the. nozzles 17 receiving low pressure steam from the-chamber '18, there is a set of nozzles24, Figs. 2 and 3, which deliver steam from the segmental chamber 25 .to the low pressure wheels. A hand-operated valve 26 controls a'port 27 between the

chambers

18 and 25 so that in case of an unusual. overload the low pressure steam can be admitted to the nozzles 24. Ordinarily,

however, the valve 26 will remain closed; the main pur.pose ofethe chamber 25 and nozzles to utilize the exhaust steam from the high pressure end of the turbine. After leavingthe wheel 6, the highpressure steam flows through a passage 28 to the chamber 25. In order -to give ample areawithout too great height, this passage is made quite wide, 50-

as shown best in Fig. 2. One ormore check valves are interposed. at a convenient point in said passage to revent any leakage of cm the first low pressure stage to the'high pressure end when the latter is not in use. Two such valves are shown, preferably arranged to be opened and r I closed positively by mechanism connected with the valve gear,of the high pressure wheel. Steam flows through these valves in parallel. The mechanism illustrated comprises ashaft 29 carrying cams 30 which act upon yokes31 attached to'the stems of the check valves. A pinion 32 on said shaft meshes with a rack 33 connected by a rod 34 of the low pressure end. B I these valves to be operated positively, I avoid all danger of their sticking to their seats or a pinion 36 011 the cam shaft 12. When the motor 14 actuates this latter shaft, the move- .ment is communicated to the cam shaft 29 and the

valves

37, 38 are opened. One of .these valves may contain a pilot valve 39 seated in an opening in the main valve and arranged to be lifted bythe cam 30 in advance of both the main valves. This affords a simple way of breaking the vacuum in the high pressure wheel chamber, since it takes far less energy to lift the pilot valve than it does tolift the entirecheck valve.

-When the turbine is running on low pressure steam, the condenser vacuum works through the unpacked shaft-bearing in the diaphragm 4 and into the high pressure end of the machine, so that the idle high pressure wheel runs in a vacuum with a minimum ofrotation losses. The check-valves.

37, 38 prevent this vacuum from being destroye'd' by' low pressure steam backing through the passage 28 from the first stage failing to work from any other cause.

. The machine operates primarily as a low pressure turbine, but in case of an increase of load beyond the capacity of the low pressure end, the motor 14 opens the high pressure valves, and the high pressure wheel suppl'ements the low pressure end, turning its exhaust also through the low pressure wheels and thusincreasing their torque.

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 desire to 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 by Letters Patent of the United States, 1s:

1. 'A mixed pressure turbine having a high pressure end and a low pressure end, and provided with a restricte constantlyopen passage between the condenser and thea passage for conveying the exhaust steam from the former to the latter, a check valve arranging in said passage, and a restricted constantlyopen passage connectingthe high pressure end with the condenser.

3. A mixed pressure turbine having a high pressure wheel-and nozzles, valve gear controlling the admission of high pressure steam to said nozzles, low pressure wheels and nozzles therefor, means for supplying with a second rack 35 which is in mesh low pressure steam t0 a portion of said noz- I zles, and means for conveying to the re--;

mainder of saidnozzles the exhaust steam 5. A 'mixed pressure.

' 6. A mixed low pressure nozzles, and operative connecs from the high pressure wheel.

4. A mixed pressure turbine havmg a high pressure w eel and nozzles, valve gear controlling .the admission of high pressure high pressure wheel and nozzles, valve gear controlling the admission of high pressure.

steam tosaid nozzles, low pressure wheels and nozzles therefor, means for supplying low pressure steamito a portion of said nozzles, a passage conveying to the remainder of said no'zz es theexhaust steam from the high pressure wheel, and one or more check valves in said passage opening toward said low pressure nozzles. V a turbine having a high pressure/wheel and nozzles, valve gear controllingthe v admission. of high pressure steam to said nozzles, low pressure wheels and nozzles therefor, means for supplying low pressure steam to a portion of said nozzles, a passage for conveying to the remainder of said nozzles the exhaust steam from the high pressure wheel, one or more check valves in said passage opening toward said low pressure nozzles, and means for ositively operating said valves when said "gh pressurevalve gear goes into operation.

ressure turbine having a high pressure w eel and nozzles, valve gear controlling the admission of high pressure steam to said nozzles, -low pressure wheels and nozzles therefor, means for supplying low pressure steam to a portion of said nozzles, ,a passage for conveying to the remainder of said nozzles'the exhaust steam from the high pressure wheel, one or. more check valves in sa d passage opening toward said tions between said valve gear.

7 A mixed pressure turbine having a yalves and high pressure high pressure wheel and nozzles,- valvegear controlling the admission of high pressure steam to said-nozzles, low pressure .wheels and nozzles therefor, mea ns for supplying.

low pressure steam to a portion of said nozzles, a passage for conveying to the remainder ofsaid nozzles the exhaust steam from high pressure valves.

8. A mixed pressure turbine having a' steam to said nozzles, low pressure wheels andnozzles .therefor, means for supplying low pressure steam to a portion of said nozzles, a wide. passage for conveylng to the remainder of said nozzles the exhaust steam from the high pressure whe'el,.and two or more check valves operating in parallel to control said passage.

.' 9. A mixed plressure turbine having a w eel and nozzles, low pressure wheels and nozzles, means for supplying low pressure nozzles, and means for admltting low pressure steam to the remainder of said nozzles at will.

10. A mixed pressure turbine having a highpressure end and a low pressure end,

means for supplying low pressure steam to v a portion of the low pressure nozzles, a pas; sage conveying the exhaust from the high pressure end to the remainder of said low pressure nozzles, one or more check valves 1n said assage, and a' hand valve for admitting-t elow pressure steam to said passage. 11. A mixed pressure turbine having a horizontal casing comprisinga condenser exhaust conduit, 3, highpressure stage chamher at one side of said conduit, low pressure stages at the other side of said conduit and discharging thereinto, a shaft extending through saidconduit and stages, and a restricted constantly-open annular passage.

around said shaft between said conduit said high pressure stage.

In wltncss whereof, I my hand this 8th day 'of August, 1913.

Q-SCAB JUN GGREN.

and

Witnesses: v BENJAMIN} B. HULL,- Hanan Onronn.

have hereunto set