Engine with combustion and expansion of the combustion gases within the combustor

• US 6,817,185 B2
• Filed: 09/30/2002
• Issued: 11/16/2004
• Est. Priority Date: 03/31/2000
• Status: Expired due to Fees

• Current Assignee: RWE Generation UK Plc (RWE AG)
• Original Assignee: RWE Generation UK Plc (RWE AG)
• Inventors: Abdallah, Hicham Salah, Richards, Roger, Coney, Michael Willboughby Essex
• Primary Examiner(s): Freay, Charles G.
• Application Number:
  US10/240,393
• Publication Number:
  US 20030049139A1
• Time in Patent Office: 778 Days
• Field of Search: 417/243, 607/72, 60/395.2, 60/395.3, 60/395.5, 60/391.2, 60/391.8, 60/395.11, 607/83, 607/74, 607/75, 606/18, 607/30
• US Class Current: 60/772
• CPC Class Codes: F02B 33/34 with rotary pumps with cell-type pressure exchangers or the like F02B33/42
• CPC Class Codes: F02B 33/443 Heating of charging air, e.g. for facilitating the starting
• CPC Class Codes: F02B 37/013 with exhaust-driven pumps arranged in series
• CPC Class Codes: F02B 37/04 Engines with exhaust drive and other drive of pumps, e.g. with exhaust-driven pump and mechanically-driven second pump
• CPC Class Codes: F02B 75/02 Engines characterised by their cycles, e.g. six-stroke
• CPC Class Codes: F02G 5/00 Profiting from waste heat of combustion engines, not otherwise provided for
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An engine comprising an isothermal air compressor (1) into which liquid is sprayed as the air is compressed. A combustion chamber (4) receives and expands the compressed air from which the liquid has been removed, to generate power. A precompressor (21, 27) compresses the air upstream of the isothermal compressor. The compressed air from the isothermal compressor receives heat from the exhaust gas from the combustion chamber in a primary heat exchanger (3). A secondary heat exchanger (31, 45) transfers heat recovered from a part of the engine to the compressed air from the isothermal compressor (1) upstream of the primary heat exchanger (3).

Claims

1. An engine comprising:

a positive displacement isothermal air compressor (1) provided with a liquid spray to spray liquid into the air as it is compressed so that the compression is substantially isothermal;

a combustion chamber (4) in which the compressed air is expanded to generate power;

means (7, 9, 11) to feed the compressed air from the isothermal compressor to the combustion chamber;

a separator (2) to remove liquid from the compressed air upstream of the combustion chamber;

a primary heat exchanger (3) for transferring heat from exhaust gas from the combustion chamber to compressed air upstream of the combustion chamber;

a precompressor (21, 27) to compress the air upstream of the isothermal compressor;

and means (30, 32) to feed the air from the precompressor to the isothermal compressor;

characterised by a secondary heat exchanger (31, 45) provided to transfer heat recovered from a part of the engine to the compressed air from the isothermal compressor (1) upstream of the primary heat exchanger (3).

2. An engine according to claim 1, wherein the heat for the secondary heat exchanger (45) is recovered from the combustion chamber (4).

3. An engine according to claim 1 or claim 2, wherein the heat for the secondary heat exchanger (31) is recovered from the air from the precompressor (21, 27).

4. An engine according to claim 2, wherein the secondary heat exchanger comprises a precompressor heat exchanger (31) and a combustion chamber heat exchanger (45) connected in parallel, and wherein the compressed air from the isothermal compressor is split into two streams (43, 44), one stream (43) being fed to the precompressor heat exchanger (31) to receive heat from air from the precompressor (21, 27), and the other stream (44) being fed to the combustion chamber heat exchanger (45) to receive heat from the combustion chamber (4);

the engine further comprising means to control the split of the flow of air from the isothermal compressor into the two streams.

5. An engine according to claims 1 and 2, arranged such that liquid (38, 41, 42) is added to the compressed air entering the secondary heat exchanger (31, 45) in a quantity which will be vaporized in the secondary heat exchanger.

6. An engine according to claim 5, wherein the secondary heat exchanger (31, 45) has a number of heat exchange elements carrying the compressed air, and wherein the liquid is directly injected into each element.

7. An engine according to claim 6, arranged such that the liquid (38) is taken from the separator (2).

8. An engine according to claim 4, wherein liquid (41, 42) is supplied to each of the compressed air streams (43, 46, 44, 47) in the precompressor heat exchanger (31) and combustion chamber heat exchanger (45) respectively;

the engine further comprising means to control the flow of liquid to the precompressor and combustion chamber heat exchangers (31, 45).

9. An engine according to claim 8, wherein the two streams (46, 47) are combined (48) upstream of the primary heat exchanger (3).

10. An engine according to claim 2, comprising a coolant circuit (49) containing liquid which cools the combustion chamber (4) and transfers the heat in the secondary heat exchanger (45) to the compressed air.

11. An engine according to claim 10, wherein the liquid is pressurised.

12. An engine according to claim 10 or claim 11, wherein the coolant circuit (49) has a liquid pump (50) for driving the liquid around the circuit.

13. An engine according to claim 12, wherein the circuit (49) includes an auxiliary cooler (51) downstream of the secondary heat exchanger (45).

14. An engine according to claim 10, wherein the secondary heat exchanger (45) comprises a high temperature heat exchanger (45H) and a low temperature heat exchanger (45L), and the coolant circuit (49) comprises a high temperature circuit (49H) and a low temperature circuit (49L), the high temperature circuit having a high temperature pump (50H) arranged to circulate liquid past a relatively high temperature part (4H) of the combustion chamber and through the high temperature heat exchanger, the low temperature circuit having a low temperature pump (50L) arranged to circulate liquid past a relatively low temperature part (4L) of the combustion chamber and through the low temperature heat exchanger, and means (44L, 44H) to feed the compressed air from the separator (2) through the low temperature heat exchanger to receive heat and subsequently through the high temperature heat exchanger to receive further heat prior to entry into the primary heat exchanger (3).

15. An engine according to claim 14, further comprising means (42L, 42H) to add water into the compressed air in separate elements of the low temperature heat exchanger (45L) all of which liquid is evaporated in the low temperature heat exchanger, and in separate elements of the high temperature heat exchanger (45H) all of which liquid is evaporated in the high temperature heat exchanger.

16. An engine according to claim 10, wherein the coolant circuit comprises a main pump (50) for pumping liquid around a main circuit including the secondary heat exchanger (45), a low temperature circuit (49L) which is fed with liquid from the main circuit, a low temperature pump (50L) for pumping liquid around the low temperature circuit past a relatively low temperature part (4L) of the combustion chamber, a high temperature circuit (49H) which is fed with a bleed flow (56) of liquid from the low temperature circuit, a high temperature pump (50H) for pumping liquid around the high temperature circuit past a relatively high temperature part (4H) of the combustion chamber, and means (57) to feed a bleed flow of liquid from the high temperature circuit to the secondary heat exchanger (45).

17. An engine according to claim 1, wherein the precompressor is arranged to be driven only partially by exhaust gas from the combustion chamber.

18. An engine according to claim 17, wherein the precompressor (21, 27) is partially driven by power generated by the expansion of gases in the combustion chamber (4).

19. An engine according to claim 18, wherein a main crankshaft (13) is driven by the expansion of gases in the combustion chamber (4), the main crankshaft being used to drive the precompressor (21, 27).

20. An engine according to claim 17, wherein the precompressor (21, 27) is partially driven by a source (22) of external power.

21. An engine according to claim 20, wherein a heat source is provided to increase the temperature of the exhaust gas driving the precompressor (27).

22. An engine according to claim 21, wherein the heat source is a burner.

23. An engine according to any one of claims 17 to 20, wherein the precompressor comprises two compressors (21, 27) connected in series, one of which (27) is driven by exhaust gas, and the other of which (21) is not.

24. An engine according to claim 23, wherein the one compressor (27) has a higher compression ratio than the other (21) compressor and wherein heat is recovered downstream of the one compressor.

25. An engine according to claim 24, wherein the one compressor (27) has a compression ratio of at least twice that of the other (21).

26. An engine according to claim 23, wherein the other compressor (21) is a rotary compressor.

27. An engine according to claim 26, wherein the rotary compressor (21) is a single-stage centrifugal compressor.

28. An engine according to claim 23, wherein the other compressor (21) is driven by a variable speed motor (22).

29. An engine according to claim 23, wherein the other compressor (21) is a variable geometry compressor.

30. An engine according to claim 29, wherein the other compressor (21) has variable inlet guide vanes.

31. An engine according to claim 20, wherein an intercooler (24) is provided to cool the air between the two compressors (21, 27) of the precompressor.

32. An engine according to claim 1, wherein an air pre-cooler (33) is provided to cool the air between the precompressor (21, 27) and the isothermal compressor (1).

33. An engine according to claim 1, wherein a spray of water is provided to cool the air prior to its entry into the isothermal compressor (1).

34. An engine according to claim 1, wherein the positive displacement isothermal compressor (1) is a reciprocating compressor in which a piston reciprocates in a cylinder to compress the air.

35. An engine according to claim 1, further comprising a storage chamber (60), means (61) to feed the compresses air from the isothermal compressor (1) to the storage chamber, means (61) to feed compressed air from the storage chamber to the combustion chamber (4), and a valve system (62, 63, 64) for selectively feeding compressed air from the isothermal compressor either to the storage chamber or to the combustion chamber, and for selectively feeding compressed air from the storage chamber to the combustion chamber.

36. An engine according to claim 35, wherein the isothermal compressor (1) and combustion chamber (4) are connected by a drive shaft (65) and wherein a motor/generator (68) is coupled to the shaft between a pair of clutches (66,67).

37. An engine according to claim 35 or claim 36, wherein a generator (71) is provided which is driven by exhaust gas from the engine and an independent power supply (22) is provided for the precompressor.

38. An engine according to claim 1, further comprising means to recover heat from a part of the engine and use the heat for a purpose external to the engine.

39. An engine according to claim 38, further comprising means to control the relative amounts of the power and heat for external use generated by the engine.

40. An engine according to claim 1, further comprising a bypass line (48A) transporting a proportion of the compressed air and/or the exhaust gas past the primary heat exchanger (4), and a by pass valve (48B) for controlling the flow through the bypass line.

41. An engine according to claim 1, wherein heat is recovered in the secondary heat exchanger from the exhaust gas from the combustion chamber (4).

42. An engine according to claim 38, wherein heat for the secondary heat exchanger is recovered from the exhaust gas (55) downstream of the precompressor.

43. An engine according to claim 38, wherein the primary heat exchanger (4) includes a number of flow paths connected to an external heating circuit.

44. A method of generating power, the method comprising compressing air in a positive displacement compressor (1);

spraying liquid into the compressor as the air is compressed so that the compression is substantially isothermal;

removing liquid from the compressed air;

feeding the compressed air to a combustion chamber (4);

injecting fuel;

combusting the fuel and expanding the combustion gases in the combustion chamber to generate power; and

feeding the exhaust gas from the combustion chamber to a primary heat exchanger (3) to heat the compressed air upstream of the combustion chamber;

characterized by recovering heat from a part of the engine and transferring this heat to the compressed air from the isothermal compressor upstream of the primary heat exchanger.

45. A method according to claim 44, further comprising the step of compressing the air in a precompressor (27, 29) upstream of the positive displacement compressor (1), and wherein the step of recovering heat comprises recovering heat from the precompressor in a precompressor heat exchanger (31) and recovering heat from the combustion chamber (4) in a combustion chamber heat exchanger (45).

46. A method according to claim 45, further comprising the steps of splitting the air from the positive displacement compressor (1) into two streams (43, 44) and feeding one stream (43) to the precompressor heat exchanger (31) and the other stream (44) to the combustion chamber heat exchanger (45), and controlling the split of the air into the two streams.

47. A method according to claim 46, further comprising controlling the fraction of air directed to each stream by means of a look-up table which specifies the required air split as a function of the various inlet conditions to the precompressor heat exchanger (31) and combustion chamber heat exchanger.

48. A method according to claim 46 or 47, further comprising the step of supplying liquid to each of the two streams (43, 44) upstream of the respective heat exchangers (31, 45) and controlling the amount of liquid supplied to each stream.

49. A method according to claim 48, further comprising the steps of monitoring the temperature differential between the incoming and outgoing streams at the hot end of each of the precompressor and combustion chamber heat exchangers (31, 45), and controlling the water flow to each of the heat exchangers so as maintain the temperature differential at a desired level.