Highly supercharged gas-turbine generating system

• US 20030182944A1
• Filed: 03/27/2003
• Published: 10/02/2003
• Est. Priority Date: 04/02/2002
• Status: Abandoned Application

• Current Assignee: Enhanced Turbine Output Holding
• Original Assignee: Enhanced Turbine Output Holding
• Inventors: Kopko, William L., Hoffman, John S.
• Application Number:
  US10/397,217
• Publication Number:
  US 20030182944A1
• Time in Patent Office: Days
• US Class Current: 60/772
• CPC Class Codes: F01K 23/10 with exhaust fluid of one cycle heating the fluid in another cycle F01K17/025 takes precedence
• CPC Class Codes: F02C 3/36 Open cycles
• CPC Class Codes: F02C 6/18 using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants using waste heat as source of energy for refrigeration plants F25B27/02; using the waste heat of a gasturbine for steam generation or in a steam cycle see F01K23/10
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02E 20/18 Integrated gasification combined cycle [IGCC], e.g. combined with carbon capture and storage [CCS]

Abstract

A highly supercharged gas-turbine generation system include a gas turbine power plant that is supercharged to a high inlet pressure, preferably over about 1.15 pressure ratio and preferably includes a transmission system with refrigerated transformers for increased output. The gas turbine power plant includes a precompressor that supercharges to a design pressure ratio of about 1.20 to 10, with a preferred pressure ratio of about 2. For high supercharging pressures, a pressure-reducer is located downstream of the gas turbine to maintain turbine outlet pressure that is close to the inlet pressure. The pressure-reducer is preferably an expander, but can alternatively be an orifice. A torque-limiting coupling on the shaft between the gas turbine and the generator prevents transient overload of the shaft. Capacity of the gas turbine plant is preferably controlled by varying supercharging pressure. The expander preferably has variable-pitch blades to allow efficient variation of turbine outlet pressure. For combined-cycle embodiments, a heat-recovery steam generator (HRSG) may be placed between the gas turbine and a downstream expander. For highest combined cycle output, a single-pressure steam system with high inlet temperature to the HRSG is preferred. The high temperature is preferably provided by supplemental firing between the gas turbine and the HRSG. An expander may be inserted between the supplemental firing and the HRSG to further improve cycle efficiency and to reduce pressure in the HRSG. For retrofit applications with limited supercharging, a refrigeration system for generator cooling may be added to increase generator output to match that available from the supercharged gas turbine.

Claims

1. A highly supercharged gas-turbine power-producing system comprising:

a. a gas turbine that comprises a compressor that receives an air stream from an inlet, compresses said air stream to provide pressurized air, a combustor that receives said pressurized air and supplies thermal energy to said pressurized air to produce a heated air stream, and a first expander that receives said heated air stream and is caused to rotate by said heated air stream, and a drive shaft that is connected to said compressor and rotated by rotation of said first expander, and

b. a supercharger that comprises a precompressor with a design pressure ratio greater than about 1.15 that supplies pre-pressurized air to the inlet of said gas turbine and thereby provides an increase in power output of said gas turbine relative to an air stream at atmospheric pressure.

2. The highly supercharged gas-turbine power-producing system of claim 1 further comprising a cooler that lowers the temperature of air leaving said precompressor to a value that is not lower than about the dewpoint temperature of air leaving the precompressor.

3. The highly supercharged gas-turbine power-producing system of claim 2 wherein the design pressure ratio of said precompressor is at least 1.20.

4. The highly supercharged gas-turbine power-producing system of claim 2 wherein said cooler does not add moisture to the air leaving the precompressor.

5. The highly supercharged gas-turbine power-producing system of claim 1 further comprising a pressure-reducing means located between an air stream outlet of said gas turbine and the atmosphere.

6. The highly supercharged gas-turbine power-producing system of claim 5 wherein said precompressor has a controllably variable output pressure.

7. The highly supercharged gas-turbine power-producing system of claim 6 wherein said pressure reducing means comprises an expander.

8. The highly supercharged gas-turbine power-producing system of claim 7 wherein said expander comprises a variable-pitch axial-flow expander.

9. The highly supercharged gas-turbine power-producing system of claim 6 wherein said pressure-reducing means comprises a damper with a variable flow area that provides a variable resistance to flow.

10. The highly supercharged gas-turbine power-producing system of claim 2 further comprising means for adjusting the cooling capacity of said cooler.

11. The highly supercharged gas-turbine power-producing system of claim 10 wherein said cooler supplies an air temperature to said gas turbine that is approximately constant.

12. The highly supercharged gas-turbine power-producing system of claim 2 wherein said cooler comprises a fogger.

13. The highly supercharged gas-turbine power-producing system of claim 5 wherein said pressure-reducing means comprises an orifice.

14. The highly supercharged gas-turbine power-producing system of claim 13 further comprising a bypass damper that allows exhaust gas to flow around said orifice with lower pressure drop and a controller that controls the operation of said precompressor and said means for bypassing exhaust gas so that when a lower power output is required, said controller opens said bypass damper and does not operate said precompressor and when increased power output is required said controller operates said precompressor and closes said bypass damper.

15. A gas-turbine power plant comprising:

a. a supercharging fan for providing a source of pressurized air;

b. a combustion turbine that comprises a compressor that receives said pressurized air from an inlet and further compresses said pressurized air, a combustor that provides thermal energy to said further pressurized air to heat said further pressurized air, and an expander that receives that heated air and is caused to rotate by said heated air;

c. an electric generator that is connected to an output shaft of said combustion turbine; and

d. a duct that connects said source of pressurized air to the inlet of said combustion turbine, which has a maximum cross-sectional area such that the average gas velocity through the maximum cross-section exceeds about 600 feet per minute.

16. The gas-turbine power plant of claim 15 further comprising a cooler that is enclosed in said duct.

17. The gas-turbine power plant of claim 16 wherein said cooler has a face that is located at an angle with respect to the plane of the cross section of said duct so as to reduce the face velocity of air through said cooler.

18. The gas-turbine power plant of claim 17 wherein said cooler has a wet surface and the face velocity of air through said cooler is selected to prevent liquid carryover from said cooler.

19. The gas-turbine power plant of claim 18 wherein said cooler is a heat pipe.

20. The gas-turbine power plant of claim 19 wherein said cooler is an indirect evaporative cooler.

21. A gas-turbine power plant comprising:

a. a heavy-duty combustion turbine that comprises a compressor and a first expander that share a common shaft which supplies a shaft output and which has an unsupercharged ISO rating of at least 50 MW and design firing temperature of at least about 2000°

F.,

b. a generator which receives said shaft output from said heavy-duty combustion turbine, and

c. pressure-reducing means located downstream of said first expander for maintaining outlet pressure of said first expander to a value the same or slightly less than inlet pressure of said compressor.

22. The gas-turbine power plant of claim 21 further comprising a precompressor that supplies pressurized air to the compressor of said gas turbine.

23. The gas-turbine power plant of claim 22 wherein said pressure-reducing means comprises a second expander that is on a shaft that is separate from said common shaft.

24. The gas-turbine power plant of claim 23 further comprising a shaft output from said second expander that is connected to an electromechanical transducer.

25. The gas-turbine power plant of claim 24 wherein said second expander drives said precompressor.

26. The gas-turbine power plant of claim 22 wherein said pressure-reducing means comprises an orifice.

27. A gas-turbine power plant comprising:

a. a compressor that produces a stream of high-pressure air,

b. a combustor that heats the high-pressure air stream to produce a stream of high-temperature, high-pressure gas,

c. an expander that expands the high-temperature, high-pressure gas stream to produce mechanical work that drives said compressor,

d. a heat-recovery steam generator that receives a high-temperature gas stream from said expander at a pressure that is at a intermediate pressure that is substantially above atmospheric and substantially below that of air exiting from said compressor, and

e. a second expander that receives a gas stream from said heat-recovery steam generator and expands it to a pressure that is approximately atmospheric.

28. The gas-turbine power plant of claim 27 further comprising a precompressor that supplies a pressurized air stream to said compressor.

29. The gas-turbine power plant of claim 28 further comprising a cooler that lowers the temperature of air before it enters said compressor.

30. The gas-turbine power plant of claim 29 wherein said cooler comprises a feedwater heater that warms water before it enters said heat-recovery steam generator.

31. The gas-turbine power plant of claim 30 wherein said cooler comprises a heat exchanger between an air stream upstream of said compressor and a gas stream entering said second expander.

32. The gas-turbine power plant of claim 29 wherein said cooler comprises means for evaporating water into the air before it enters said compressor.

33. A gas-turbine power plant comprising:

a. a combustion turbine that comprises a compressor, a combustor, and a first expander, and a shaft output that is connected to said first expander,

b. a generator connected to said shaft output,

c. a precompressor that pressurizes air to inlet of said combustion turbine, and

d. a torque-limiting device that is connected between the shaft output of said gas turbine and said generator so as to prevent transient overload of said shaft output.

34. A gas-turbine power plant comprising:

a. a gas turbine,

b. a precompressor,

c. a generator with an input shaft that receives power from said gas turbine and an output shaft that drives said precompressor, and

d. a first clutch that drivingly connects said output shaft from said generator to said precompressor so that said clutch engages to drive said precompressor when supercharging is required and said clutch disengages to allow operation of said gas turbine without said precompressor when supercharging is not required.

35. The gas-turbine power plant of claim 34 further comprising a speed reducer between said precompressor and said the shaft output from said generator.

36. The gas-turbine power plant of claim 35 further comprising a bypass damper that allows air to flow around said precompressor when supercharging is not required.

37. The gas-turbine power plant of claim 36 further comprising a brake that prevents rotation of said precompressor when supercharging is not required.

38. The gas-turbine power plant of claim 36 wherein said precompressor comprises at least two compressor stages with a first stage connected to said output shaft from said generator by means of said first clutch and a second stage is connected to an output shaft from said first stage by a second clutch so that when a lower supercharging pressure is required said first clutch is engaged to drive said first compressor stage and when a higher supercharging pressure is required said second clutch engages so as to drive said second compressor stage.

39. The gas turbine power plant of claim 34 wherein said precompressor is a radial-flow device.

40. A combined-cycle power plant comprising:

a. a gas turbine,

b. a precompressor that supplies pressurized air to said gas turbine,

c. a steam cycle that comprises a heat-recovery steam generator receives hot gas from said gas turbine, and

d. a duct burner with a design firing temperature of at least about 1400°

F. that is located between said gas turbine and said steam cycle and that heats said hot gas from said gas turbine.

41. The combined-cycle power plant of claim 40 wherein said steam cycle is a single-pressure steam cycle.

42. The combined-cycle power plant of claim 41 wherein said the design firing temperature of said duct burner is at least about 1800°

F.

43. The combined-cycle power plant of claim 42 further comprising an expander that is located between said duct burner and said heat-recovery steam generator.

44. The combined-cycle power plant of claim 42 further comprising an expander that located downstream of said heat-recovery steam generator.

45. The combined-cycle power plant of claim 40 further comprising means for varying pressure output of said precompressor so as to vary the output of said power plant.

46. A method of enhancing output of a gas turbine power plant comprising:

a. pressurizing an air stream to a pressure ratio greater than about 1.15,

b. cooling said air stream to a temperature that is above about the dewpoint temperature of said air stream, and

c. supplying said cooled, pressurized air stream to the inlet of a gas turbine.

47. The method of claim 46 further wherein said cooling results in a temperature that is above about the dewpoint temperature of the air.

48. The method of claim 46 wherein said pressure ratio for pressurizing said air stream is above about 1.5.

49. The method of claim 48 further comprising the step of providing a pressure drop between said gas turbine and the atmosphere.

50. The method of claim 49 wherein said pressure drop is provided by an expander.

51. The method of claim 49 wherein said pressure drop is provided by an orifice.

52. An electrical power-producing system comprising:

a. an alternating-current power producer that comprises a winding that is wrapped around a magnetic core;

b. means for producing a changing magnetic field through said magnetic core,

c. refrigeration means for cooling a refrigerant to a temperature below the ambient wet-bulb temperature by evaporating said refrigerant,

d. a first fluid circuit comprising a first fluid that circulates in a substantially closed loop through said alternating-current power producer, a pumping means for circulating said first fluid through said circuit, and said refrigeration means, and

e. a non-refrigerating cooling means for providing cooling for said first fluid without operation of said refrigeration means;

wherein said means for producing induces an alternating current in said winding of said alternating-current power producer and said refrigeration means cools said closed fluid loop which cools said alternating-current power producer and thereby increases the power output capability of said power producer, and said non-refrigerating cooling means provides auxiliary cooling when said refrigeration means is not operating.

53. The electrical power-producing system of claim 52 wherein said alternating-current power producer is a generator.

54. The electrical power-producing system of claim 52 wherein said alternating-current power producer is a transformer.

55. The electrical power-producing system method of claim 52 wherein said refrigeration means comprises a chiller.

56. The electrical power-producing system method of claim 55 wherein said nonrefrigerating cooling means comprises a heat exchanger between said first fluid and a unrefrigerated fluid and means for moving said unrefrigerated fluid through said heat exchanger.

57. The electrical power-producing system of claim 56 wherein said unrefrigerated fluid is ambient air and said means for moving said unrefrigerated fluid comprises a fan.

58. The electrical power-producing system of claim 56 further comprising a cooling tower and wherein said unrefrigerated fluid is water that is cooled in said cooling tower and said means for moving said unrefrigerated fluid comprises a pump.

59. The electrical power-producing system of claim 56 wherein said heat exchanger is located in said first fluid circuit in series flow arrangement with said refrigeration means.

60. The electrical power-producing system of claim 52 further comprising transmission means between said power producer and an electrical load for transmitting electrical power produced by said power producer to said electrical load.

61. A method for enhancing output of a gas-turbine power plant that comprises a combustion turbine that drives an electric generator, said method comprising the steps of:

pressurizing and cooling inlet air to said combustion turbine;

cooling a fluid to a temperature that is substantially below the turbine inlet air temperature; and

supplying said cooled fluid to said generator so that the capacity of the cooled generator matches the available power output of said combustion turbine.

62. The method of claim 61 wherein said fluid is cooled to a temperature that is below about the wet-bulb temperature of the turbine inlet air.

63. The method of claim 61 wherein said fluid is cooled using a refrigeration system.

64. A gas-turbine power plant comprising:

a. a gas turbine,

b. a generator that is driven by said gas turbine,

c. a supercharging fan that supplies pressurized air to said gas turbine, and

d. a refrigeration system that supplies fluid at a temperature that is below the inlet air to said gas turbine for cooling said generator.

65. A power generation and distribution system comprising:

a. a highly supercharged gas turbine power plant having a design pressure ratio of greater than 1.15;

b. a transformer for receiving electrical power produced by said power plant and modifying a voltage level of said electrical power;

c. a refrigeration system for cooling said transformer; and

d. a controller that modulates the output of said gas turbine power plant in response to changes in system demand, by controlling operation of said refrigeration system and by controlling supercharging of said gas turbine power plant.

66. A highly supercharged gas-turbine power-producing system comprising:

a. a gas turbine that comprises a compressor that receives an air stream from an inlet, compresses said air stream to provide pressurized air, a combustor that receives said pressurized air and supplies thermal energy to said pressurized air to produce a heated air stream, and a first expander that receives said heated air stream and is caused to rotate by said heated air stream, and a drive shaft that is connected to said compressor and rotated by rotation of said first expander,

b. a supercharger that comprises a precompressor with a design pressure ratio greater than about 1.15 that supplies pre-pressurized air to the inlet of said gas turbine and thereby provides an increase in power output of said gas turbine relative to an air stream at atmospheric pressure;

c. a duct that connects said precompressor to the inlet of said gas turbine, which has a maximum cross-sectional area such that the average gas velocity through the maximum cross-section exceeds about 600 feet per minute;

d. a heat-recovery steam generator that receives a high-temperature gas stream from said first expander at a pressure that is at a intermediate pressure that is substantially above atmospheric and substantially below that of air exiting from said compressor, and

e. a second expander that receives a gas stream from said heat-recovery steam generator and expands it to a pressure that is approximately atmospheric.

67. A power-generation and transmission system comprising:

a. at least one gas turbine

b. a precompressor that supplies air pressurized to a pressure ratio greater than about 1.20 to said gas turbine

c. an electric generator that is driven by said gas turbine

d. an electrical power transmission system that comprises a high-voltage power line that receives alternating-current power from said generator and transmits a transformer that supplies electrical power at a reduced voltage to an electrical load.

68. The power-generation and transmission system of claim 67 wherein said pressure ratio of said precompressor is greater than about 1.5.

69. The power-generation and transmission system of claim 68 further comprising a controller that activates operation of said precompressor and said gas turbine in response to increased electrical load on the transmission system.

70. A gas turbine that is suitable for operating with a high level of supercharging comprising:

a. a compressor that pressurizes a stream of air,

b. an expander that extracts work from expanding hot, high-pressure gas to a lower pressure and drive said compressor,

c. an output shaft that is driven by said expander

d. a generator that is mechanically connected to said output shaft

e. a combustor with a design output that is substantially greater than that required to provide a design firing temperature at sea-level barometric pressure and a turbine inlet air temperature of −

40°

F.

71. The gas turbine of claim 70 wherein the design power output limit of said output shaft is substantially greater than the rated unsupercharged power output of said gas turbine at sea-level barometric pressure and an inlet air temperature of −

40°

F.