Generated system bottoming cycle

• US 6,539,720 B2
• Filed: 11/06/2001
• Issued: 04/01/2003
• Est. Priority Date: 11/06/2000
• Status: Expired due to Term

• Current Assignee: Capstone Turbine Corp.
• Original Assignee: Capstone Turbine Corp.
• Inventors: Calta, David, Treece, Bill, Willis, Jeff, Rouse, Gregory C.
• Primary Examiner(s): NGUYEN, HOANG M
• Application Number:
  US09/985,789
• Publication Number:
  US 20020066270A1
• Time in Patent Office: 511 Days
• Field of Search: 60/391.82, 606/51, 606/71
• US Class Current: 60/651
• 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: F01K 25/08 using special vapours
• 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

Abstract

A closed loop Rankine bottoming cycle including a heat exchanger coupled to an exhaust port of a first turbogenerator for heating a pressurized refrigerant into a gaseous phase, and a second turbogenerator (e.g., a turbo expander) coupled to the heat exchanger for expanding the gaseous phase so as to create power. Also included is a cooling mechanism coupled to an exhaust of the second turbogenerator for cooling the gaseous phase exhausted by the second turbogenerator into a liquid phase, and a pumping mechanism for pressurizing the liquid phase into the pressurized refrigerant heated by the heat exchanger. A computer program product and method for operating and synchronizing the generator included in the closed loop, so as to optimize the overall system efficiency is also included.

Claims

1. A closed loop Rankine bottoming cycle, comprising:

a heat exchanger coupled to an exhaust port of a first turbogenerator, and configured to heat a pressurized refrigerant into a gaseous phase, wherein the first turbogenerator is a variable speed Brayton cycle turbogenerator;

a second turbogenerator coupled to the heat exchanger, and configured to expand the gaseous phase so as to create power, wherein the second turbogenerator is a variable speed Rankine cycle turbogenerator;

a cooling mechanism coupled to an exhaust of the second turbogenerator, and configured to cool the gaseous phase exhausted by the second turbogenerator into a liquid phase; and

a pumping mechanism configured to pressurize the liquid phase into the pressurized refrigerant heated by the heat exchanger, wherein the pumping mechanism receives the liquid phase solely from the cooling mechanism and supplies the liquid phase to the heat exchanger.

2. The closed loop Rankine bottoming cycle according to claim 1, further comprising:

a heat sink coupled to the heat exchanger and configured to discharge excess heat output from the heat exchanger.

3. The closed loop Rankine bottoming cycle according to claim 1, wherein the first turbogenerator is a MICRO-TURBINE generator.

4. The closed loop Rankine bottoming cycle according to claim 1, wherein the second turbogenerator is a turbo expander comprising one of a radial turbine, an axial turbine, and a Pelton wheel turbine.

5. The closed loop Rankine bottoming cycle according to claim 4, wherein a rotating speed of a turbo expander shaft included in the turbo expander is configured to vary so as to optimize a performance of the turbo expander.

6. The closed loop Rankine bottoming cycle according to claim 4, wherein the turbo expander directly drives a permanent magnet generator.

7. The closed loop Rankine bottoming cycle according to claim 4, wherein the permanent magnet generator is integral with a turbine rotor shaft included in the turbo expander.

8. The closed loop Rankine bottoming cycle according to claim 4, wherein the permanent magnet generator is coupled with a turbine rotor shaft included in the turbo expander via a coupling mechanism.

9. The closed loop Rankine bottoming cycle according to claim 8, wherein the coupling mechanism comprises a CAPSTONE double diaphragm.

10. The closed loop Rankine bottoming cycle according to claim 4, wherein the turbo expander is hermetically sealed.

11. The closed loop Rankine bottoming cycle according to claim 4, wherein the pumping mechanism is mechanically driven by the turbo expander.

12. The closed loop Rankine bottoming cycle according to claim 1, wherein the pumping mechanism is electrically driven by an external electric power source.

13. The closed loop Rankine bottoming cycle according to claim 1, wherein the pumping mechanism comprises a CAPSTONE foil bearing compressor.

14. The closed loop Rankine bottoming cycle according to claim 1, wherein the first turbogenerator comprises a non-utility turbogenerator and the power created by the second turbogenerator feeds other devices collocated with the non-utility turbogenerator.

15. The closed loop Rankine bottoming cycle according to claim 1, further comprising:

a condenser control valve disposed between the cooling mechanism and an inlet of the pumping mechanism; and

a control mechanism configured to vary a condensing pressure in the cooling mechanism so as to also vary a dew point.

16. The closed loop Rankine bottoming cycle according to claim 15, wherein the control mechanism varies the condenser control valve, a speed of the pumping mechanism, and a speed of the second turbogenerator for optimal cycle efficiency.

17. The closed loop Rankine bottoming cycle according to claim 16, wherein the control mechanism comprises a computer program product.

18. A method of operating a closed loop Rankine bottoming cycle, comprising:

heating a pressurizing refrigerant into a gaseous phase via a heat exchanger coupled to an exhaust port of a first turbogenerator, wherein the first turbogenerator is a variable speed Brayton cycle turbogenerator;

expanding the gaseous phase so as to create power via a second turbogenerator coupled to the heat exchanger;

cooling the gaseous phase exhausted by the second turbogenerator into a liquid phase via a cooling mechanism coupled to an exhaust of the second turbogenerator, wherein the second turbogenerator is a variable speed Rankine cycle turbogenerator; and

pressurizing the liquid phase into the pressurized refrigerant heated by the heat exchanger via a pumping mechanism, wherein the pumping mechanism receives the liquid phase solely from the cooling mechanism and supplies the liquid phase to the heat exchanger.

19. The method according to claim 18, further comprising:

discharging excess heat output from the heat exchanger via a heat sink coupled to the heat exchanger.

20. The method according to claim 18, wherein the first turbogenerator is a MICRO-TURBINE generator.

21. The method according to claim 18, wherein the second turbogenerator is a turbo expander comprising one of a radial turbine, an axial turbine, and a Pelton wheel turbine.

22. The method according to claim 21, further comprising:

varying a rotating speed of a turbo expander shaft included in the turbo expander so as to optimize a performance of the turbo expander.

23. The method according to claim 21, wherein the turbo expander directly drives a permanent magnet generator.

24. The method according to claim 21, wherein the permanent magnet generator is integral with a turbine rotor shaft included in the turbo expander.

25. The method according to claim 21, wherein the permanent magnet generator is coupled with a turbine rotor shaft included in the turbo expander via a coupling mechanism.

26. The method according to claim 25, wherein the coupling mechanism comprises a CAPSTONE double diaphragm.

27. The method according to claim 21, wherein the turbo expander is hermetically sealed.

28. The method according to claim 21, wherein the pumping mechanism is mechanically driven by the turbo expander.

29. The method according to claim 18, wherein the pumping mechanism is electrically driven by an external electric power source.

30. The method according to claim 18, wherein the pumping mechanism comprises a CAPSTONE foil bearing compressor.

31. The method according to claim 18, wherein the first turbogenerator comprises a non-utility turbogenerator and the power created by the second turbogenerator feeds other devices collocated with the non-utility turbogenerator.

32. The method according to claim 18, further comprising:

disposing a condenser control valve between the cooling mechanism and an inlet of the pumping mechanism; and

varying the condenser valve, via a control mechanism, so as to vary a condensing pressure in the cooling mechanism and also vary a dew point.

33. The method according to claim 32, wherein the control mechanism varies the condenser control valve, a speed of the pumping mechanism, and a speed of the second turbogenerator for optimal cycle efficiency.

34. The method according to claim 33, wherein the control mechanism comprises a computer program product.

35. A system of operating a closed loop Rankine bottoming cycle, comprising:

means for heating a pressurized refrigerant into a gaseous phase and being coupled to an exhaust port of a first turbogenerator, wherein the first turbogenerator is a variable speed Brayton cycle turbogenerator;

means for expanding the gaseous phase so as to create power and being coupled to the heat exchanger;

means for cooling the gaseous phase exhausted by a second turbogenerator into a liquid phase and being coupled to an exhaust of the second turbogenerator, wherein the second turbogenerator is a variable speed Rankine cycle turbogenerator; and

means for pressurizing the liquid phase into the pressurized refrigerant heated by the heating means, wherein the pressurizing means receives the liquid phase solely from the cooling means and supplies the liquid phase to the heating means.

36. The system according to claim 35, further comprising:

means for discharging excess heat output from the heating means and being coupled to the heating means.

37. The system according to claim 35, wherein the first turbogenerator is a MICRO-TURBINE generator.

38. The system according to claim 35, wherein the second turbogenerator is a turbo expander comprising one of a radial turbine, an axial turbine, and a Pelton wheel turbine.

39. The system according to claim 38, further comprising:

means for varying a rotating speed of a turbo expander shaft included in the turbo expander so as to optimize a performance of the turbo expander.

40. The system according to claim 38, wherein the turbo expander directly drives a permanent magnet generator.

41. The system according to claim 38, wherein the permanent magnet generator is integral with a turbine rotor shaft included in the turbo expander.

42. The system according to claim 38, wherein the permanent magnet generator is coupled with a turbine rotor shaft included in the turbo expander via a coupling means.

43. The system according to claim 42, wherein the coupling means comprises a CAPSTONE double diaphragm.

44. The system according to claim 38, wherein the turbo expander is hermetically sealed.

45. The system according to claim 38, wherein the pumping means is mechanically driven by the turbo expander.

46. The system according to claim 35, wherein the pumping means is electrically driven by an external electric power source.

47. The system according to claim 35, wherein the pumping means comprises a CAPSTONE foil bearing compressor.

48. The system according to claim 35, wherein the first turbogenerator comprises a non-utility turbogenerator and the power created by the second turbogenerator feeds other devices collocated with the non-utility turbogenerator.

49. The system according to claim 35, further comprising:

means for varying a condensing pressure in the cooling means so as to also vary a dew point.

50. The system according to claim 49, wherein the varying means varies a condenser control valve disposed between the cooling means and pumping means, a speed of the pumping means, and a speed of the second turbogenerator for optimal cycle efficiency.

51. The system according to claim 49, wherein the varying means comprises a computer program product.