System and method for recovering waste heat
View Patent ↗A waste heat recovery system includes at least two integrated rankine cycle systems coupled to at least two separate heat sources having different temperatures. The first rankine cycle system is coupled to a first heat source and configured to circulate a first working fluid. The second rankine cycle system is coupled to at least one second heat source and configured to circulate a second working fluid. The at least one second heat source includes a lower temperature heat source than the first heat source. The first and second working fluid are circulatable in heat exchange relationship through a cascading heat exchange unit for condensation of the first working fluid in the first rankine cycle system and evaporation of the second working fluid in the second rankine cycle system.
1. A waste heat recovery system including at least two integrated rankine cycle systems, the recovery system comprising:
a heat generation system comprising at least two separate heat sources having different temperatures;
a first rankine cycle system comprising a first expander, wherein the first rankine cycle system is coupled to a first heat source among the at least two separate heat sources and configured to circulate a first working fluid; wherein the first rankine system is configured to remove heat from the first heat source;
a second rankine cycle system comprising a second expander and a condenser; wherein the second rankine cycle system is coupled to at least one second heat source among the at least two separate heat sources and configured to circulate a second working fluid, the at least one second heat source comprising a lower temperature heat source than the first heat source, wherein the second rankine cycle system is configured to remove heat from the at least one second heat source;
a cascaded heat exchange unit, wherein the first and second working fluids are circulatable in heat exchange relationship through the cascaded heat exchange unit for condensation of the first working fluid in the first rankine cycle system and evaporation of the second working fluid in the second rankine cycle system;
a partial evaporator configured to partially evaporate the second working fluid before entering the cascaded heat exchange unit;
a pump situated between the condenser and the partial evaporator; and
a first control valve situated in a by-pass path between the condenser and the partial evaporator,
wherein the at least one second heat source is configured to partially evaporate the second working fluid before entering the cascaded heat exchange unit in a cycle of the second rankine cycle system.
2. The recovery system of claim 1 , wherein the first rankine cycle system further comprises an evaporator coupled to the first heat source, and wherein the first heat source comprises an engine exhaust unit.
3. The recovery system of claim 2 , wherein the evaporator is coupled to the engine exhaust unit via a thermal oil heat exchanger, an exhaust economizer, or combinations thereof.
4. The recovery system of claim 3 , wherein the first working fluid from the cascaded heat exchange unit is fed through the exhaust economizer.
5. The recovery system of claim 1 , wherein the first working fluid comprises steam.
6. The recovery system of claim 1 , wherein the first working fluid comprises a first organic working fluid.
7. The recovery system of claim 6 , wherein the first organic working fluid comprises cyclohexane, cyclopentane, thiophene, ketones, aromatics, or combinations thereof.
8. The recovery system of claim 1 , wherein the second expander comprises a radial type expander, an axial type expander, or an impulse type expander.
9. The recovery system of claim 1 , wherein the condenser is coupled to the at least one second heat source selected from a group comprising an oil heat exchanger, an engine jacket, a water jacket heat exchanger, a lower temperature intercooler, a higher temperature intercooler, or combinations thereof.
10. The recovery system of claim 9 , wherein the lower temperature intercooler and the higher temperature intercooler are provided respectively to an upstream side and a downstream side of the cascaded heat exchange unit.
11. The recovery system of claim 9 , wherein the condenser is coupled to the oil heat exchanger, the engine jacket, the water jacket heat exchanger, the engine jacket, the lower temperature intercooler, the higher temperature intercooler, or combinations thereof through the partial evaporator configured to partially evaporate the second working fluid before entering the cascaded heat exchange unit.
12. The recovery system 11 , further comprising a second control valve coupled between the partial evaporator and the condenser, and configured to control the flow of the second working fluid to the condenser during system ramp up and shut down conditions.
13. The recovery system 11 , further comprising a pressure reduction valve coupled between the partial evaporator and the condenser and configured to control the pressure of the second working fluid flowing from the partial evaporator to the condenser during system ramp up and shut down conditions.
14. The recovery system of claim 11 , further comprising a third control valve coupled between the partial evaporator and the cascaded heat exchange unit and configured to control the flow of the second working fluid from the partial evaporator to the cascaded heat exchange unit.
15. The recovery system of claim 11 , wherein the condenser is coupled to the oil heat exchanger, the partial evaporator, the water jacket heat exchanger, the engine jacket, the lower temperature intercooler, the higher temperature intercooler, or combinations thereof.
16. The recovery system of claim 1 , wherein the condenser is coupled to at least two second heat sources selected from a group comprising an oil heat exchanger, an engine jacket, a water jacket heat exchanger, a lower temperature intercooler, a higher temperature intercooler, or combinations thereof.
17. The recovery system of claim 1 , wherein the condenser is coupled to a group of heat sources selected from a group comprising an oil heat exchanger, an engine jacket, a water jacket heat exchanger, a lower temperature intercooler, a higher temperature intercooler, or combinations thereof.
18. The recovery system of claim 1 , wherein the control valve is operable to control the flow of the second working fluid entering the partial evaporator.
19. The recovery system of claim 1 , wherein the cascaded heat exchange unit is coupled to the second expander via a higher temperature intercooler configured to complete evaporation or to heat the second working fluid to a substantially higher temperature before entering the second expander.
20. The recovery system of claim 1 , wherein the second working fluid comprises a second organic working fluid.
21. The recovery system of claim 20 , wherein the second organic working fluid comprises propane, butane, pentafluoro-propane, pentafluoro-butane, pentafluoro-polyether, oil, or combinations thereof.
22. The recovery system of claim 1 , wherein the first expander and the second expander are coupled to a generator unit.
23. The recovery system of claim 1 , wherein the first expander and the second expander are coupled a first generator unit and a second generator unit respectively.
24. The recovery system of claim 1 , wherein the second rankine cycle system is configured to remove heat from the first heat source.
25. The recovery system of claim 1 , wherein the heat generation system comprises a combustion engine.
26. A waste heat recovery system including at least two integrated organic rankine cycle systems, the recovery system comprising:
a combustion engine comprising one heat source having an engine exhaust unit; and at least one other heat source selected from a group comprising an oil heat exchanger, an engine jacket, a water jacket heat exchanger, a lower temperature intercooler, a higher temperature intercooler, or combinations thereof;
a first organic rankine cycle system comprising a first expander, wherein the first organic rankine cycle system is coupled to the engine exhaust unit and configured to circulate a first organic working fluid; wherein the first organic rankine system is configured to remove heat from the engine exhaust unit;
a second organic rankine cycle system comprising a second expander and a condenser; wherein the second organic rankine cycle system is coupled to the at least one other heat source selected from the group comprising the oil heat exchanger, the engine jacket, the water jacket heat exchanger, the lower temperature intercooler, the higher temperature intercooler, or combinations thereof; and configured to circulate a second organic working fluid, the one heat source comprising a higher temperature heat source than the at least one other heat source, wherein the second organic rankine cycle system is configured to remove heat from the at least one other heat source;
a cascaded heat exchange unit, wherein the first and second organic working fluids are circulatable in heat exchange relationship through the cascaded heat exchange unit for condensation of the first organic working fluid in the first organic rankine cycle system and evaporation of the second organic working fluid in the second organic rankine cycle system;
a partial evaporator configured to partially evaporate the second working fluid before entering the cascaded heat exchange unit;
a pump situated between the condenser and the partial evaporator; and
a first control valve situated in a by-pass path between the condenser and the partial evaporator,
wherein the at least one other heat source is configured to partially evaporate the second organic working fluid before entering the cascaded heat exchange unit in a cycle of the second rankine cycle system.
27. The recovery system of claim 26 , wherein the first organic rankine cycle system further comprises an evaporator coupled to the engine exhaust unit.
28. The recovery system of claim 27 , wherein the evaporator is coupled to the engine exhaust unit via a thermal oil heat exchanger, an exhaust economizer, or combinations thereof.
29. The recovery system of claim 28 , wherein the first organic working fluid from the cascaded heat exchange unit is fed through the exhaust economizer.
30. The recovery system of claim 26 , wherein the condenser is coupled to the at least one other heat source selected from the group comprising the oil heat exchanger, the engine jacket, the water jacket heat exchanger, the lower temperature intercooler, the higher temperature intercooler, or combinations thereof.
31. The recovery system of claim 30 , wherein the lower temperature intercooler and the higher temperature intercooler are provided respectively to an upstream side and a downstream side of the cascaded heat exchange unit.
32. The recovery system of claim 26 , wherein the condenser is coupled to at least two other heat sources selected from the group comprising the oil heat exchanger, the engine jacket, the water jacket heat exchanger, the lower temperature intercooler, the higher temperature intercooler, or combinations thereof.
33. The recovery system of claim 26 , wherein the condenser is coupled to a group of other heat sources selected from the group comprising the oil heat exchanger, the engine jacket, the water jacket heat exchanger, the lower temperature intercooler, the higher temperature intercooler, or combinations thereof.
34. The recovery system of claim 26 , further comprising a partial evaporator; wherein the condenser is coupled to the oil heat exchanger, the engine jacket, the water jacket heat exchanger, the engine jacket, the lower temperature intercooler, the higher temperature intercooler, or combinations thereof through the partial evaporator.