Claims
- 1. In a steam turbine adapted to operate at less than a full load, apparatus for transferring between a full-arc admission mode and a partial-arc admission mode, comprising:
- a source of motive steam;
- a steam chest receiving said motive steam from said source, said steam chest including a plurality of valves each of which are connected to a respective nozzle chamber via turbine inlet piping and are set for a minimum admission of said motive steam into the turbine below 100%;
- bar lift means for actuating at least one pair of said valves;
- high-pressure means for actuating remaining ones of said plurality of valves;
- means for controlling said bar lift means and said high pressure means; and
- means for crosstying a flow of said motive steam through selected pairs of said nozzle chambers to achieve 50% minimum admission.
- 2. The apparatus according to claim 1, wherein said source comprises a nuclear reactor.
- 3. The apparatus according to claim 1, wherein said plurality of valves comprises four valves arranged within said steam chest in a single line.
- 4. The apparatus according to claim 3, wherein said crosstying means connect the turbine inlet piping of an outboard one of said plurality of valves with the turbine inlet piping of an inboard one of said plurality of valves.
- 5. The apparatus according to claim 4, wherein the turbine inlet piping of each said outboard valve is connected to the turbine inlet piping of its adjacent inboard valve.
- 6. The apparatus according to claim 1, wherein said plurality of valves comprises three valves arranged within said steam chest in a single line.
- 7. The apparatus according to claim 6, further comprising another steam chest.
- 8. The apparatus according to claim 7, wherein said crosstying means connect the turbine inlet piping of an inboard valve of each said steam chest to the turbine inlet piping of an outboard valve of said other steam chest.
- 9. The apparatus according to claim 1, wherein said crosstying means comprises:
- a pipe coupling each said selected pair; and
- a valve, in said pipe, controlling the admission of steam through said pipe.
- 10. The apparatus according to claim 9, wherein said valve is non-modulating.
- 11. The apparatus according to claim 9, wherein said valve is modulating.
- 12. A steam turbine, comprising:
- a casing including inlet means for receiving a flow of steam and means for exhausting said flow of steam;
- stator means mounted within said casing, said stator means including a stationary set of blades for directing said flow of steam;
- rotor means including a shaft having a rotatable set of blades mounted thereon adjacent to said stationary set of blades for receiving said flow of steam directed by said stator means and for transmitting work performed thereby to a load through said shaft; and
- steam chest means for regulating said flow of steam through said inlet means, said steam chest means comprising a plurality of valves each of which are connected to a respective nozzle chamber via turbine inlet piping and are set for a minimum admission of said flow of steam to said inlet means below 100%, bar lift means for actuating at least one pair of said valves, high pressure means for actuating remaining ones of said plurality of valves, and means for crosstying said flow of steam through selected pairs of said nozzle chambers whereby the turbine is adapted to be transferred between a full-arc admission mode and a partial-arc admission mode without excessive thermal stress.
- 13. The turbine according to claim 12, wherein said plurality of valves are linearly arranged within said steam chest means.
- 14. The turbine according to claim 12, wherein said steam chest means is formed integrally with said casing.
- 15. The turbine according to claim 12, wherein said steam chest means comprises a pair of steam chests each with three valves arranged in a single line.
- 16. The turbine according to claim 15, wherein said crosstying means connect the turbine inlet piping of an inboard valve of each said steam chest to the turbine inlet piping of an outboard valve of said other steam chest.
- 17. The turbine according to claim 12, wherein said plurality of valves comprises four valves arranged within said steam chest in a single line.
- 18. The turbine according to claim 17, wherein said plurality of valves comprises three valves arranged within said steam chest in a single line.
- 19. The turbine according to claim 18, wherein the turbine inlet piping of each said outboard valve is connected to the turbine inlet piping of its adjacent inboard
- 20. In a multistage steam turbine which includes a pair of steam chests each having a plurality of linearly arranged valves connected to respective nozzle chambers through turbine inlet pipes, a method of reducing thermal stress in the turbine during transfers between a full-arc admission mode and a partial-arc admission mode comprising the steps of:
- connecting selected pairs of the turbine inlet pipes of said valves by crosstie means including a pipe adapted to couple a flow of steam through the nozzle chambers corresponding to said selected pairs and a crosstie valve in said pipe;
- opening each said crosstie valve prior to the transfer to couple the flow of steam therethrough; and
- sequentially closing said crosstie valves to minimize a temperature change in the first stage of the turbine.
- 21. In a steam turbine having an integrally-mounted steam chest including a plurality of linearly-arranged valves each of which are connected to a respective nozzle chamber, each said nozzle chamber being separated from the next adjacent nozzle chamber by a ligament, apparatus for reducing a temperature differential across the ligaments during transfer of the turbine from a full-arc admission mode to a partial-arc admission mode, comprising:
- a manifold receiving a supply of steam;
- crosstie lines connected between said manifold and selected ones of said nozzle chambers; and
- a plurality of crosstie valves, each said valve installed within a respective one of said crosstie lines.
- 22. The apparatus according to claim 21, wherein said selected ones of said nozzle chambers comprise each said nozzle chamber inboard of the nozzle chambers corresponding to the outermost ones of said linearly arranged plurality of valves.
- 23. The apparatus according to claim 22, further comprising means for sequentially opening said crosstie valves.
- 24. In a steam turbine adapted to operate at less than a full load, the turbine receiving motive stea from a source, apparatus for transferring between a full-arc admission mode and a partial-arc admission mode, comprising:
- a steam chest receiving the motive steam, said steam chest including a plurality of valves each of which are connected to a respective nozzle chamber via turbine inlet piping and are set for a minimum admission of the motive steam into the turbine below 100%; and
- crosstie means connecting the turbine inlet piping of selected pairs of said nozzle chambers downstream of said valves. and adapted to couple a flow of steam through the nozzle chambers corresponding to said selected pairs.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S Ser. No. 107,735 filed Oct. 13, 1987.
US Referenced Citations (17)
Foreign Referenced Citations (3)
Number |
Date |
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366826 |
Jan 1923 |
DE2 |
485669 |
Nov 1917 |
FRX |
0046391 |
Mar 1984 |
JPX |
Continuation in Parts (1)
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Number |
Date |
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107735 |
Oct 1987 |
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