USRE13772E - mrxed pressxe t txebine - Google Patents

Description

O. JUNGGREN. MIXED PRESSURE TUR mE.

Reissued 11113 14, 1914.

A'PPLIOATION FILED JUNE 5. 191%.

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Reissued July 14, 1914 APPLIUATION FILED JUNE 5, 1914.

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MIXED PRESSURE TURBINE.

XPPLIUATION FILED JUNE 5,1914.

Reissued July 14. 1914.

pressure throttle valve has'become wide wheel to run idle when themachine is open To all whom it may) concern:

.(lGfiClBIlC in this resaeet bein made u b D .tate in a vacuunrwith minimum losses. The

v, UNITED strains PATENT or uon.

oscAn JUN GBEN, or scnENnoTAnY,.NEw YORK, ASSIGNOR T0. GENERAL nnneraxo COMPANY, A CORPORATION on NEW roan.

Specification of Reissued Letters Patent. Rgiigg d July 14, 1914 Original Ila 1,091,345, dated March 24, 1914, Serial fie. 733,977. Applicationf or reissue filed. June 5, 1914.

Serial No.

Be it known, that I, OSCAR JUNGGREN, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Mixed-Pressure Turbines, of which the following is a specification.

This invention relates to elastic fluid turbines'and especially to those of the .mixed pressure type wherein provision is made for utilizing low pressure steam so long as the supply 'issutficient to carry the load, any

high pressuresteam admitted after the low open. In such systemsit is, of course, dea sir-able tohave the highest eflieiency possible when the unit-is run with low pressure steam as well when'it is supplied with high pressure fluid. Hereto'lore it has been pro-- posed for the sake of simplicity to use a portion of the first bucket wheel for high pres.

sure. lVhile this is cheaper, it is not the mt'ast economical arrangement, as the buckets are designed necessarily for low pressure operation" and are not so eflicient when sup plied 'with high pressure steam. Another arrangement is to have one of the wheels equipped with buckets properly designed for high pressure steam only, and allow this ating 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. Another suggestion is to make the high pressure part of the unit quite independentof the 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 off, so that when the high ressure en'd is running idle the wheel wil ro-.

two parts of the turbine are connected 5 a.

passage controlled by an automatic vs. vewhich opens when the high pressure steam is admitted-to its stage,jand permits said steam to exhaust into the low pressure. end of the turbine. y

My inventionrelates to a mixed pressure turbine of this latter class, but I have sim- "low pressure end of the unit.

plified the construction and made the ma-,

it upon the buckets of the first stage low I pressure wheels. I also arrange for admltting the low pressure steam to these special nozzles in case of an extraordinary overload. Two or more automatic valves are used-in the passage which conveys the exha'ust from the high pressure wheel to the special low pressure nozzles; and these valves are arranged to operate in parallel. In the accompanying drawings, l lgure 1 is an end elevation, partly in section of a mixed pressure turbine embodying my improvements; Fig. 2 is a sectional end elevation, taken on the line 22 of Fig.3; Fig. 3

is a vertical longitudinalsection, and Fig. l is an enlarged sectional view of one of the automatic check valves controlling the passage between the high pressure end and the The'turbine illustrated is a horizontal; ma

chine of the Curtis type. The shaft 1 passes from the downwardly-opening condenser e25 haust conduit forming astage chamber for one or more bucket wheels 6 mounted on the shaft 1. Only one stage and one wheel are shown in the drawing, 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 openi11g' from a'zste am chest- 8 connected with the steam 'inain' 9, Fig. l. The nozzles are controlled by nozzle valves 10, which are operated by any suitablecontrol mechanism. I have illustrated a. familiar construction, in which each valve is liftedeby a lever 11,0perated by a'camf' on a shaft12, whiph is geared to a racki13 actuated by a liydraillic motor 14. The pilot 1 valve of this motor is controlled by the speed-responsive governor l5.

The opening in the diaphragm 4 through which the shaft 1 passes is not packed, and affords a restricted opening through which the condenser vacuum may work into the high pressure stage when the high pressure 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 escapearound the 1 shaft directly into the condenser, but the amount of such leakage steamwill not be serious owing to the restricted 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 a plurality of such wheels. The low pressure steam is applied to the first of these wheels through nozzles 17, Fig. .3, which receive steam from the nearly annular chamber 18, Figs. 2 and 3, concentric with the shaft and communicating directly with the low pressure steam main 19. -A butterfly 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 21,'Fig. 1, segment gear 22 and operativ connections between said gear and the spin is of said valve. The arrangement is such that the motor opens the low pressure throttle valve wide, before beginning to open the high pressurenozzlc valves. A hand-operated 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. i

In addition to the nozzles 17 receiving low pressure steam from the chamber 18, there is a set of nozzles 2i, Figs. 2 and 3. which deliver steam from the segu'icntal 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 :ullnitted to the nozzles 24. Ordinarily, however, the valve 26 will remain closed; the main purpose of the chamber- 25 and nozzles 24 being to utilize the exhaust steam from the high pressure end ofthc turbine. After leaving the wheel 6, the high pressure steam flows through a passagc'28 to the chamber In order to give ample area without too great height, this passage is made quite wide, as shown best in Fig. 2. One or more check valves are interposed at atconvcnient point in said passage to prevent any leakage of low pressure steam from the first low pressure stage to the high pressure end when the latter is not in use. Two such valves ar shown, preferably arranged to be opened and closed positively by hechanisin connected with the valve gear of the high pressure wheel, Steam ;lloivs through these valves in parallel. The mechanism illustrated comprises a shaft 29 carrying earns 39 which act upon yokes 31 attached to the stems of the check valves. A pinion 32 on said shaftmeshes with a rack 33 connected by a rod 34 with second rack 35 which is in mesh with a pinion 36 on the cam shaft 12. When the motor 14 'aetuates this latter shaft, the movement is communicated to the camshaft .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 by the cam 30 in advance of both the main valves. This af fords 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 to lift the entire check 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 pres: sure wheel runs in a vacuum with a minimum of rotation losses. The check- valves 37, 38 prevent this vacuum from being destroyed by low pressure, steam backing through the passage 28 from the first stage of the low pressure end. By arranging these valves to be operated positively, I avoid all. danger of their sticking to their seats or. failing to work from any other cause.

The machine operatesprimarily as a low pressure turbine, but in. case of an increase of load beyond the capacity of the low pressure end, the motor lei Opens the high pres sure valves, and the high pressure wheel supplements the low pressure end, turning its exhaust also through the low pressure wheels and :thus iucrcasiim their torque.

In accordance with the provisions of the patent statutes, 1 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.

hat I claim as new and desire to secure by Letters Patent of the United States, is

'l. A mixed pressure turbine having a high pressure end and a low pressure OIl(l,ZH.1Ll provided with a restricted constantly-open passage between the condenser and the high n'cssure stage. for establishing a vacuum in the high pressure end when the machine running on low pressure steam.

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 low pressure steam to a portion of said nozzles, and means for conveying to the remainder of said nozzlesthe exhaust steam from thehigh pressure Wheel.

4. 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 low pressure steam to a portion of said nozzles, a passage for conveying to the remain der of said nozzles the exhaust steam from the high pressure Wheel, and one or more check valves in. said passage opening toward said low pressure nozzles.

5. 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 10v: 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 positively operating said valves when said high pressure valve ear goes into operation.

6. A mixed press re turbine having a high pressure Wheel and nozzles, valve gear 0 ntrolling 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 pressureljv'vheel, one'or more check valves in said passage opening toward said low pressure nozzles, and operative connections between said valves and the high pressure valve gear.

7. A mixed pressure turbine having a high pressure wheel and nezz'les, valve gear controlling the admission oifj high pressure steam to said nozzles, low pressure Wheels and nozzles therefdg', 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 pressurewheel, one or more check valves in said passage opening toward said low pressure nozzles, and a pilot valve seated in an opening in one of said check valves.

8. 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 low pressure steam to a portion of said nozzles, a Wide passage for conveying to the rcmainder' of said nozzles the exhaust st am from the high pressure heel, and two or more check valves operating in parallel to control said passage.

9. A mixed pressure turbine having a high pressure wheel and nozzles, low pressure Wheels and nozzles, means for supplying low pressure steam to a portion of said low pressure nozzles, and means for admitting low pressure steam to the remainder of said nozzles at will.

10. A mixed pressure turbine having a high pressure end and a 10W pressure end, means for supplying low pressure steam to a portion of the lou pressure nozzles, a passage conveying the exhaust from the high pressure end to the remainder of said low pressure nozzles, one or more check valves in said passage, and a hand valve for admit ting the low pressure steam to said passage.

11. A mixed pressure turbine having a horizontal casing comprising a condenser exhaust conduit, a high pressure stage chamher at one side of said conduit, low pressure stages at the other side of said conduit and 9 0 discharging thereinto, a shaft extending through said conduit and stages, and a re-. stricted constantly open annular passage around said shaft between said conduit and said high pressure stage.

In'wltness whereof, I have hereunto set my hand this 8th day of August, 1913.

OSCAR J UNGGREN.

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