US20100242476A1

US20100242476A1 - Combined heat and power cycle system

Info

Publication number: US20100242476A1
Application number: US12/413,920
Authority: US
Inventors: Gabor Ast; Thomas Johannes Frey; Pierre Sebastien Huck; Herbert Kopecek
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2009-03-30
Filing date: 2009-03-30
Publication date: 2010-09-30

Abstract

A combined heat and power cycle system includes a heat generation system having at least two separate heat sources having different temperatures. The combined heat and power cycle system includes a first rankine cycle system coupled to a first heat source among the at least two separate heat sources and configured to circulate a first working fluid. A 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 first and second working fluids are circulatable in heat exchange relationship through a 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. At least one heat exchanger is disposed at one or more locations in the first rankine cycle system, second rankine cycle system, or combinations thereof.

Description

BACKGROUND

The embodiments disclosed herein relate generally to the field of a combined heat and power cycle system and, more particularly, to a combined heat and power cycle system for recovering waste heat from a plurality of heat sources having different temperatures for heating purpose and generation of electricity.
Enormous amounts of waste heat are generated by a wide variety of industrial and commercial processes and operations. Example sources of waste heat include heat from space heating assemblies, steam boilers, engines, and cooling systems. When waste heat is low grade, such as waste heat having a temperature of heat below 840 degrees Fahrenheit, for example, conventional heat recovery systems do not operate with sufficient efficiency to make recovery of energy cost-effective. The net result is that vast quantities of waste heat are simply dumped into the atmosphere, ground, or water.
Some power generation systems provide better reliability and off-grid operation with alternate fuels such as biogas or landfill gas, with examples being gas turbines and combustion engines such as microturbines and reciprocating engines. Combustion engines may be used to generate electricity using fuels such as gasoline, natural gas, biogas, plant oil, and diesel fuel. However, atmospheric emissions such as nitrogen oxides and particulates may be emitted.
One method to generate electricity from the waste heat of a combustion engine without increasing the output of emissions is to apply a bottoming rankine cycle. A fundamental rankine cycle typically includes a turbo generator, an evaporator/boiler, a condenser, and a liquid pump. In another method to generate electricity from waste heat, single cycle system or two-cycle systems are used in heat recovery applications with waste heat sources of different temperature levels. Single-cycle configurations collect heat from the different waste heat locations in a serial arrangement of heat exchangers with an intermediate heating fluid. In two-cycle configurations, the hot heat source heats a high-boiling point liquid in a top loop, and the cold heat source heats a low-boiling point liquid in a separate bottom loop. In another conventional system provided to generate electricity from waste heat, a cascaded organic rankine cycle system for utilization of waste heat includes a pair of organic rankine cycle systems. The cycles are combined, and the respective organic working fluids are chosen such that the organic working fluid of the first organic rankine cycle is condensed at a condensation temperature that is above the boiling point of the organic working fluid of the second organic cycle.
Most of the conventional systems discussed above, are used to exclusively produce power. In other words, the conventional systems provide less flexibility in the ratio between power and heat produced.
There is a need for a combined heat and power cycle system that provides flexibility in the ratio between power and heat produced.

BRIEF DESCRIPTION

In accordance with one exemplary embodiment disclosed herein, a combined heat and power cycle system including at least two integrated rankine cycle systems is provided. The combined heat and power cycle system includes a heat generation system comprising at least two separate heat sources having different temperatures. The combined heat and power cycle system includes a first rankine cycle system coupled to a first heat source among the at least two separate heat sources and configured to circulate a first working fluid. The first rankine system is configured to remove heat from the first heat source. A 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 includes a lower temperature heat source than the first heat source. The second rankine cycle system is configured to remove heat from the at least one second heat source. The first and second working fluids are circulatable in heat exchange relationship through a 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. At least one heat exchanger is disposed at one or more locations in the first rankine cycle system, second rankine cycle system, or combinations thereof. The first working fluid, second working fluid, or combinations thereof are circulatable in heat exchange relationship with a third fluid through the at least one heat exchanger for heating the third fluid.
In accordance with one exemplary embodiment disclosed herein, a combined heat and power cycle system including at least two integrated organic rankine cycle system is provided. The combined heat and power cycle system includes a combustion engine having an engine exhaust unit; and at least another heat source selected from a group comprising an oil heat exchanger, engine jacket, water jacket heat exchanger, lower temperature intercooler, higher temperature intercooler, or combinations thereof. The combined heat and power cycle system includes a first organic rankine cycle system coupled to the engine exhaust unit and configured to circulate a first organic working fluid. A second organic rankine cycle system is coupled to at least one other heat source selected from the group comprising the oil heat exchanger, engine jacket, water jacket heat exchanger, lower temperature intercooler, higher temperature intercooler, or combinations thereof, and configured to circulate a second organic working fluid. The one heat source includes a lower temperature heat source than at least one other heat source. The second organic rankine cycle system is configured to remove heat from the at least one other heat source. The first and second organic working fluids are circulatable in heat exchange relationship through a 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. At least one heat exchanger is disposed at one or more locations in the first rankine cycle system, second rankine cycle system, or combinations thereof. The first working fluid, second working fluid, or combinations thereof, are circulatable in heat exchange relationship with the third fluid through the at least one heat exchanger for heating the the third fluid.
In accordance with one exemplary embodiment disclosed herein, a combined heat and power cycle system including at least two integrated rankine cycle systems is provided. The combined heat and power cycle system includes a heat generation system comprising at least two separate heat sources having different temperatures. The combined heat and power cycle system includes a first rankine cycle system coupled to a first heat source among the at least two separate heat sources and configured to circulate a first working fluid. The first rankine system is configured to remove heat from the first heat source. A 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 includes a lower temperature heat source than the first heat source. The second rankine cycle system is configured to remove heat from the at least one second heat source. The first and second working fluids are circulatable in heat exchange relationship through a 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. The second rankine cycle is configured to partially evaporate the second working fluid before entering the cascaded heat exchange unit. At least one heat exchanger is disposed at one or more locations in the first rankine cycle system, second rankine cycle system, or combinations thereof. The first working fluid, second working fluid, or combinations thereof are circulatable in heat exchange relationship with a third fluid through the at least one heat exchanger for heating the third fluid.

DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatical representation of a combined heat and power cycle system having two integrated organic rankine cycle systems in accordance with an exemplary embodiment disclosed herein;

FIG. 2 is a diagrammatical representation of a combined heat and power cycle system having two integrated organic rankine cycle systems in accordance with another exemplary embodiment disclosed herein;

FIG. 3 is a diagrammatical representation of a combined heat and power cycle system having two integrated organic rankine cycle systems in accordance with yet another exemplary embodiment disclosed herein;

FIG. 4 is a diagrammatical representation of a bottom cycle of a combined heat and power cycle system in accordance with an exemplary embodiment disclosed herein;

FIG. 5 is a diagrammatical representation of a combined heat and power cycle system having two integrated organic rankine cycle systems in accordance with yet another exemplary embodiment disclosed herein;

FIG. 6 is a diagrammatical representation of a bottom cycle of a combined heat and power cycle system in accordance with an exemplary embodiment disclosed herein; and

FIG. 7 is a diagrammatical representation of a bottom cycle of a combined heat and power cycle system in accordance with an exemplary embodiment disclosed herein.

DETAILED DESCRIPTION

As discussed in detail below, embodiments of the present invention provide a combined heat and power cycle system having at least two integrated rankine cycle systems coupled to at least two separate heat sources respectively 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 second heat source includes a lower temperature heat source than the first heat source. The combined heat and power cycle system also includes a cascaded heat exchange unit. The first and second working fluids are circulated in heat exchange relationship 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. In accordance with the exemplary embodiments of the present invention, the combined heat and power cycle system includes one or more heat exchangers disposed at one or more locations in the first rankine cycle system, second rankine cycle system, or combinations thereof for heating a third fluid to be used for a particular locality. In some embodiments, the third fluid comprises water, water mixed with anti-corrosive agent, or water mixed with anti-freezing agent. The provision of additional heat exchangers for heating purpose enables flexible heat extraction and power generation. Although the combined heat and power cycle system in the exemplary embodiments of FIGS. 1-9 is described with reference to combustion engines, the system is also applicable to other heat generation systems such as gas turbines, geothermal, solar thermal, industrial and residential heat sources, or the like.
As a preliminary matter, the definition of the term “or” for the purpose of the following discussion and the appended claims is intended to be an inclusive “or.” That is, the term “or” is not intended to differentiate between two mutually exclusive alternatives. Rather, the term “or” when employed as a conjunction between two elements is defined as including one element by itself, the other element itself, and combinations and permutations of the elements. For example, a discussion or recitation employing the terminology “A” or “B” includes: “A” by itself, “B” by itself, and any combination thereof, such as “AB” and “BA.” Furthermore, it is of note that the present discussion relates to exemplary embodiments, and the appended claims should not be limited to the embodiments discussed.
Referring to FIG. 1, a combined heat and power cycle system 10 is illustrated in accordance with an exemplary embodiment of the present invention. The illustrated combined heat and power cycle system 10 includes a first organic rankine cycle system 12 (top cycle) and a second organic rankine cycle system 14 (bottom cycle). A first organic working fluid is circulated through the first organic rankine cycle system 12. The first organic working fluid may include cyclohexane, cyclopentane, thiophene, ketones, aromatics, or combinations thereof. The first organic rankine cycle system 12 includes an evaporator 16 coupled to a first heat source 18, for example an exhaust unit of a heat generation system 19 (for example, an engine). In one example, the temperature of the exhaust unit of the engine may be in the temperature range of 400 to 500 degrees Celsius. The evaporator 16 receives heat from the exhaust gas generated from the first heat source 18 and generates a first organic working fluid vapor. The first organic working fluid vapor is passed through a first expander 20 to drive a first generator unit 22. After passing through the first expander 20, the first organic working fluid vapor at a relatively lower pressure and lower temperature is passed through the cascaded heat exchange unit 24. The first organic working fluid vapor is condensed into a liquid, which is then pumped via a pump 26 to the evaporator 16. The cycle may then be repeated.
The cascaded heat exchange unit 24 is used both as a condenser for the first organic rankine cycle system 12 and as an evaporator for the second organic rankine cycle system 14. A second organic working fluid is circulated through the second organic rankine cycle system 14. The second organic working fluid may include propane, butane, pentafluoro-propane, pentafluoro-butane, pentafluoro-polyether, oil, or combinations thereof. It should be noted herein that list of first and second organic working fluids are not inclusive and other organic working fluids applicable to organic rankine cycles are also envisaged. In certain other exemplary embodiments, the first or second organic working fluid includes a binary fluid. The binary fluid may include cyclohexane-propane, cyclohexane-butane, cyclopentane-butane, or cyclopentane-pentafluoropropane, for example. Cascaded heat exchange unit 24 may be coupled to any one or more of a plurality of second heat sources such as an intercooler 28, an oil heat exchanger 30, and a cooling water jacket heat exchanger 32 being coupled either in series or parallel. Such second heat sources are also typically coupled to the engine. It should be noted herein that the second heat source includes a lower temperature heat source than the first heat source. It should be noted that in other exemplary embodiments, first and second heat sources may include other multiple low-grade heat sources such as gas turbines with intercoolers. The cascaded heat exchange unit 24 receives heat from the first organic working fluid and generates a second organic working fluid vapor. The second organic working fluid vapor is passed through a second expander 34 to drive a second generator unit 36. In certain other exemplary embodiments, the first expander 20 and the second expander 34 are coupled to a single generator unit.
In an exemplary embodiment, neither of the first and second organic working fluids are expanded below the atmospheric pressure, and the boiling point temperature of the first organic working fluid is below the average temperature of the second heat source. After passing through the second expander 34, the second organic working fluid vapor at lower pressure and lower temperature is passed through a condenser 38. The second organic working fluid vapor is condensed into a liquid, which is then pumped via a pump 40 to the second heat sources. In the illustrated embodiment, the second organic working fluid is pumped sequentially via the intercooler 28, the oil heat exchanger 30, and the cooling water jacket heat exchanger 32. The cycle may then be repeated.
The cascaded organic rankine cycle system facilitates heat recovery over a temperature range that is too large for a single organic rankine cycle system to accommodate efficiently. In one embodiment, the intercooler 28, the oil heat exchanger 30, and the cooling water jacket heat exchanger 32 are coupled along a single cooling loop in which the second organic working fluid is heated and partially evaporated. The illustrated layout of the second heat sources facilitates effective heat removal from the plurality of lower temperature engine heat sources. This increases the effectiveness of the cooling systems and provides effective conversion of waste heat into electricity. In another exemplary embodiment of the present invention, the heat generation system may include a gas turbine system. Steam may be circulated through the top cycle and the second organic working fluid may be circulated through the bottom cycle. Steam is condensed and passed in heat exchange relationship with the second organic working fluid through the cascaded heat exchange unit 24.
In the illustrated embodiment, one or more first heat exchangers 41 are disposed at a location 42 between the intercooler 28 and the oil heat exchanger 30, or at a location 44 between the oil heat exchanger 30 and the cooling water jacket heat exchanger 32, or at a location 46 between the cooling water jacket heat exchanger 32 and the cascaded heat exchange unit 24 of the second organic rankine cycle system 14. The first heat exchanger 41 may also be disposed at a location 48 between the cascaded heat exchange unit 24 and the second expander 34, or at a location 50 between the expander 34 and the condenser 38. The second organic working fluid is circulated in heat exchange relationship with water, or water mixed with anti-corrosive agent, or water mixed with anti-freezing agent (third fluid) through the first heat exchanger 41, for heating the water, for example water supplied to a particular locality. One or more second heat exchangers 52 are disposed at a location 54 between the evaporator 16 and first expander 20, or at a location 56 between the first expander 20 and the cascaded heat exchange unit 24 of the first organic rankine cycle system 12. The first organic working fluid is circulated in heat exchange relationship with water through the second heat exchanger 52, for heating the water. In the illustrated embodiment, valves may be provided to the first and second rankine cycle systems 12, 14 to divert the flow of the first and second organic working fluid through the second and first heat exchangers 52, 41 respectively. It should be noted herein that even though water is mentioned, other fluids are also envisaged.
During winter season, both the heat exchangers 41, 52 may be operated. When more heat is needed for heating the water, heat is extracted from the engine cooling system and transferred to the second organic working fluid. Heat is then extracted from the second organic working fluid via the first heat exchanger 41 for heating the water. Also, heat may be extracted from the first organic fluid via the second heat exchanger 52 for heating the water. During spring or autumn season, either one of heat exchangers 41, 52 may be active. During summer season, neither of the heat exchangers 41, 52 are active.
In certain embodiments, when the first heat exchanger 41 disposed at any one of the locations 42, 44, 46, and 48 upstream of the expander 34 is in active state, the second organic rankine cycle system 14 may not be used to generate power. In certain other embodiments, when the first heat exchanger 41 disposed at a location 50 downstream of the expander 34 is in active state, the second organic rankine cycle system 14 may be used to generate power.
In some embodiments, when the second heat exchanger 52 disposed at a location 54 upstream of the expander 20 is in active state, the first organic rankine cycle system 12 may not be used to generate power. In certain other embodiments, when the second heat exchanger 52 disposed at a location 56 downstream of the expander 20 is in active state, the first organic rankine cycle system 12 may be used to generate power. In some embodiments, when the second heat exchanger 52 is not active, heat is input from the first organic rankine cycle system 12 to the second organic rankine cycle system 14. All such permutations and combinations are envisaged, thus facilitating higher power to heat ratio flexibility.
Referring to FIG. 2, a combined heat and power cycle system 10 is illustrated in accordance with another exemplary embodiment of the present invention. As discussed above, the illustrated combined heat and power cycle system 10 includes the first organic rankine cycle system 12 and the second organic rankine cycle system 14. In the illustrated embodiment, the first organic rankine cycle system 12 includes the evaporator 16 coupled to the first heat source 18, i.e. the exhaust unit of the engine, via a thermal oil heat exchanger 58. In the illustrated embodiment, the thermal oil heat exchanger 58 is a shell and tube type heat exchanger. The thermal oil heat exchanger 58 is used to heat thermal oil to a relatively higher temperature using exhaust gas of the engine. The evaporator 16 receives heat from the thermal oil and generates a first organic working fluid vapor. The thermal oil is then pumped back from the evaporator 16 to the thermal oil heat exchanger 58 using a pump 60.
In the illustrated embodiment, the cascaded heat exchange unit 24 is coupled to a plurality of second heat sources such as the intercooler 28, the oil heat exchanger 30, and an engine jacket 62 via a partial evaporator 64. The partial evaporator 64 receives heat from a cooling water loop that collects heat from the oil heat exchanger 30, the engine jacket 62, and the intercooler 28 and generates a partially evaporated second organic working fluid two-phase stream. The second organic working fluid stream is passed through the cascaded heat exchange unit 24 for complete evaporation or even superheating of the second organic working fluid. The fluid in the cooling water loop is pumped via a pump 66 to the oil heat exchanger 30, before being supplied to the engine jacket, 62, and the intercooler 28 before it enters the partial evaporator 64.
In the illustrated embodiment, one or more first heat exchangers 41 are disposed at a location 68 between the pump 66 and the oil heat exchanger 30, or at a location 70 between the oil heat exchanger 30 and the engine jacket 62, or at a location 72 between the engine jacket 62 and the intercooler 28, or at a location 74 between the intercooler 28 and the partial evaporator 64 of the second organic rankine cycle system 14. The cooling water is circulated in heat exchange relationship with water to be heated through the first heat exchanger 41, for heating purpose. In an alternate embodiment, the first heat exchanger 41 may also be disposed at a location 76 between the partial evaporator 64 and the cascaded heat exchange unit 24. In such an embodiment, the second organic working fluid is circulated in heat exchange relationship with water through the first heat exchanger 41.
One or more second heat exchangers 52 are disposed at a location 78 between the pump 60 and the thermal oil heat exchanger 58, or at a location 80 between the thermal oil heat exchanger 58 and the evaporator 16 of the first organic rankine cycle system 12. The thermal oil is circulated in heat exchange relationship with water through the second heat exchanger 52, for heating the water.
In certain embodiments, when the first heat exchanger 41 disposed at any one of the locations 68, 70, 72, 74 in the cooling loop is in active state, no heat may be input from the cooling loop to the second organic working fluid. In certain other embodiments, when the first heat exchanger 41 disposed at a location 76 downstream of the partial evaporator 64 is in active state, the second rankine cycle system 14 may not be used to generate power.
In some embodiments, when the second heat exchanger 52 disposed at any one of the locations 78, 80 in thermal oil loop is in active state, no heat may be input from the thermal oil loop to the first organic working fluid, and the first organic rankine cycle system 12 may not be used to generate power.
Referring to FIG. 3, a combined heat and power cycle system 10 is illustrated in accordance with another exemplary embodiment of the present invention. In the illustrated embodiment, the cascaded heat exchange unit 24 is coupled to a plurality of second heat sources such as the intercooler 28, the oil heat exchanger 30, and the water jacket heat exchanger 32. In the illustrated embodiment, the second organic working fluid is sequentially passed through the lower temperature intercooler 28, the oil heat exchanger 30, and the water jacket heat exchanger 32 before entering the cascading heat exchange unit 24. The second heat sources are used to preheat or partially vaporize the second organic working fluid entering the cascading heat exchange unit. In the illustrated embodiment, the intercooler 28 is a lower temperature intercooler. The cascaded heat exchange unit 24 receives heat from the first organic working fluid and generates a second organic working fluid vapor. The second organic working fluid vapor is passed through a higher temperature intercooler 82 to the second expander 34 to drive the second generator unit 36. In the illustrated embodiment, the lower temperature intercooler 28 performs preheating of the second organic working fluid flowing to the cascaded heat exchange unit 24. The higher temperature intercooler 82 provided downstream of the cascaded heat exchange unit 24 is used to heat the second organic working fluid exiting from the cascaded heat exchange unit 24 to a relatively higher temperature, to complete evaporation or to superheat the second organic working fluid.
In the illustrated embodiment, the first heat exchanger 41 may be disposed at a location 84 between the cascaded heat exchange unit 24 and the high temperature intercooler 82, or a location 86 between the high temperature intercooler 82 and the second expander 34. In certain embodiments, when the first heat exchanger 41 disposed at any one of the locations 84, 86 upstream of the second expander 34 is in active state, the second organic rankine cycle system 14 may not be used to generate power.
Referring to FIG. 4, the second organic rankine cycle system 14 (bottom cycle) of the combined heat and power cycle system 10 is illustrated in accordance with an exemplary embodiment of the present invention. In the illustrated embodiment, the cascaded heat exchange unit 24 is coupled to a plurality of second heat sources such as the intercooler 28, the oil heat exchanger 30, and the water jacket heat exchanger 32. The second heat sources are used to preheat or partially vaporize the second organic working fluid entering the cascading heat exchange unit 24. The cascaded heat exchange unit 24 receives heat from the first organic working fluid and generates a second organic working fluid vapor. In the illustrated embodiment, the second organic working fluid vapor is passed in heat exchange relationship with the engine exhaust gas (generated from the engine exhaust unit 18) via a heat exchanger 94. The heat exchanger 94 provided downstream of the cascaded heat exchange unit 24 is used to heat the second organic working fluid exiting from the cascaded heat exchange unit 24 to a relatively higher temperature, to complete evaporation or to superheat the second organic working fluid. In certain other exemplary embodiments, the heat exchanger 94 may be provided to the upstream side of the cascaded heat exchange unit 24.
In the illustrated embodiment, the first heat exchanger 41 may be disposed at a location 88 between the cascaded heat exchange unit 24 and the heat exchanger 94, or a location 90 between the heat exchanger 94 and the second expander 34. In certain embodiments, when the first heat exchanger 41 disposed at the location 88 upstream of the heat exchanger 94 is in active state, the second organic rankine cycle system 14 may still be used to generate power. In certain other embodiments, when the first heat exchanger 41 disposed at the location 90 downstream of the heat exchanger 94 is in active state, the second organic rankine cycle system 14 may not be used to generate power.
Referring to FIG. 5, a combined heat and power cycle system 10 is illustrated in accordance with an exemplary embodiment of the present invention. In the illustrated embodiment, the first organic rankine cycle system 12 includes the evaporator 16 coupled to the first heat source, i.e. the exhaust unit of the engine, via a thermal oil heat exchanger 58 and an exhaust economizer 92. The thermal oil is then pumped back from the evaporator 16 to the thermal oil heat exchanger 58 using a pump 60. A drying valve 94 is provided between the evaporator 16 and the first expander 20 and is configured to remove traces of moisture from the first organic fluid vapor exiting the evaporator 16. In the illustrated embodiment, the condensed liquid (i.e. first organic working fluid) from the cascaded heat exchange unit 24 is pumped via the pump 26 to the exhaust economizer 92. The condensed liquid is heated prior to being supplied to the evaporator 16.
In the illustrated embodiment, the cascaded heat exchange unit 24 is coupled to a plurality of second heat sources such as the lower temperature intercooler 28, the oil heat exchanger 30, the water jacket heat exchanger 32, and the higher temperature intercooler 82. The cascaded heat exchange unit 24 receives heat from the first organic working fluid and generates a second organic working fluid vapor. The heat sources disclosed herein may be coupled in series or parallel. The relative positions of the heat sources may also be varied depending upon the requirement. In the illustrated embodiment, the second organic working fluid is passed through the lower temperature intercooler 28, the oil heat exchanger 30, the water jacket heat exchanger 32, and the higher temperature intercooler 82 before entering the cascaded heat exchange unit 24.
In the illustrated embodiment, the first heat exchanger 41 may be disposed at a location 96 between the oil heat exchanger 30 and the water jacket heat exchanger 32, or a location 98 between the oil heat exchanger 30 and the higher temperature intercooler 82. In certain embodiments, when the first heat exchanger 41 disposed at any one of the locations 96, 98 is in active state, the second organic rankine cycle system 14 may not be used to generate power.
Referring to FIG. 6, the second organic rankine cycle system 14 (bottom cycle) of the combined heat and power cycle system 10 is illustrated in accordance with an exemplary embodiment of the present invention. The cascaded heat exchange unit 24 is coupled to a plurality of second heat sources such as the lower temperature intercooler 28, the oil heat exchanger 30, the water jacket heat exchanger 32, the engine jacket 62, and the higher temperature intercooler 82. A pump 100 is provided to circulate cooling water between the jacket heat exchanger 32 and the engine jacket 62. In the illustrated embodiment, the second organic working fluid is passed sequentially through the lower temperature intercooler 28, the oil heat exchanger 30, the water jacket heat exchanger 32 and the higher temperature intercooler 82 before entering the cascading heat exchange unit 24.
In the illustrated embodiment, the first heat exchanger 41 may be disposed at a location 102 between the pump 100 and the engine jacket 62, or a location 104 between the engine jacket 62 and the water jacket heat exchanger 32. Alternately, the first heat exchanger 41 may be disposed at a location 106 between the water jacket heat exchanger 32 and the higher temperature intercooler 82, or a location 108 between the higher temperature intercooler 82 and the cascaded heat exchange unit 24.
In certain embodiments, when the first heat exchanger 41 disposed at any one of the locations 102, 104 in the cooling loop is in active state, no heat may be input from the cooling loop to the second organic working fluid and the second organic rankine cycle system 14 may still be used to generate power. In certain other embodiments, when the first heat exchanger 41 disposed at any one of the locations 106, 108 upstream of the cascaded heat exchange unit 24 is in active state, the second organic rankine cycle system 14 may not be used to generate power.
Referring to FIG. 7, the second organic rankine cycle system 14 (bottom cycle) of the combined heat and power cycle system 10 is illustrated in accordance with an exemplary embodiment of the present invention. The cascaded heat exchange unit 24 is coupled to a plurality of second heat sources such as the oil heat exchanger 30, the engine jacket 62, and the intercooler 28. The cascaded heat exchange unit 24 receives heat from the first organic working fluid and generates a second organic working fluid vapor. In the illustrated embodiment, the intercooler 28, the oil heat exchanger 30, and the engine jacket 44 performs preheating or partial vaporization of the second organic working fluid flowing to the cascaded heat exchange unit 24.
In the illustrated embodiment, the first heat exchanger 41 may be disposed at a location 110 between the oil heat exchanger 30 and the engine jacket 62, or a location 112 between the engine jacket 62 and the intercooler 28, or a location 114 between the intercooler 28, and the cascaded heat exchange unit 24. In certain embodiments, when the first heat exchanger 41 disposed at any one of the locations 110, 112, 114 is in active state, the second organic rankine cycle system 14 may still be used to generate power.
It should be noted herein that with reference to FIGS. 1-7, the activation of the first and second heat exchangers 41, 52, and the first and second organic rankine cycle systems 12, 14 are exemplary embodiments. It should also be noted that the activation criterior may be varied depending the application such as amount of power and heat required. In one embodiment, when power requirement is more and heat requirement is less, both the first and second heat exchangers 41, 52 may be deactivated and both the first and second rankine cycle systems 12, 14 are activated to generate power. In another embodiment, either one of the first and second heat exchangers 41, 52 may be activated, and both the first and second rankine cycle systems 12, 14 are activated to generate power. In such a more specific embodiment, one of the rankine cycle system may be operated at part-load. In another embodiment, when the heat requirement is more and power requirement is less, both the first and second heat exchangers 41, 52 may be activated and either one of the first and second rankine cycle systems 12, 14 are activated to generate power. All such permutations and combinations are envisaged. All the embodiments discussed herein facilitate flexible generation of heat and power. When the power requirement is more, less heat is extracted. When power requirement is less, more heat is generated.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

1. A combined heat and power cycle system including at least two integrated rankine cycle systems, the combined heat and power cycle system comprising:

a heat generation system comprising at least two separate heat sources having different temperatures;

a first rankine cycle system 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 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; and

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; and

at least one heat exchanger disposed at one or more locations in the first rankine cycle system; second rankine system, or combinations thereof; wherein the first working fluid, second working fluid, or combinations thereof are circulatable in heat exchange relationship with a third fluid through the at least one heat exchanger for heating the third fluid.

2. The combined heat and power cycle system of claim 1, wherein the third fluid comprises water, or water mixed with anti-corrosive agent, or water mixed with anit-freezing agent.

3. The combined heat and power cycle system of claim 1, wherein the second working fluid comprises a second organic working fluid.

4. The combined heat and power cycle system of claim 1, wherein the second organic working fluid comprises propane, butane, pentafluoro-propane, pentafluoro-butane, pentafluoro-polyether, oil, or combinations thereof.

5. The combined heat and power cycle system of claim 1, wherein the second rankine cycle system comprises a condenser 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.

6. The combined heat and power cycle system of claim 5, wherein the one or more locations in the second rankine cycle system comprises one or more locations between the plurality of second heat sources.

7. The combined heat and power cycle system of claim 5, wherein the one or more locations in the second rankine cycle system comprises a location between the at least one second heat source and the cascaded heat exchange unit.

8. The combined heat and power cycle system of claim 5, wherein the one or more locations in the second rankine cycle system comprises a location between the cascaded heat exchange unit and an expander.

9. The combined heat and power cycle system of claim 5, wherein the one or more locations in the second rankine cycle system comprises a location between an expander and the condenser.

10. The combined heat and power cycle system of claim 5, 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 combined heat and power cycle system of claim 10, wherein the one or more locations in the second rankine cycle system comprises a location between the cascaded heat exchange unit and the high temperature intercooler.

12. The combined heat and power cycle system of claim 9, wherein the one or more locations in the second rankine cycle system comprises a location between the high temperature intercooler and an expander.

13. The combined heat and power cycle system of claim 5, wherein the at least one second heat source is configured to partially evaporate the second working fluid before entering the cascaded heat exchange unit.

14. The combined heat and power cycle system of claim 5, 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 configured to partially evaporate the second working fluid before entering the cascaded heat exchange unit.

15. The combined heat and power cycle system of claim 14, wherein the one or more locations in the second rankine cycle system comprises one or more locations between the partial evaporator and 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.

16. The combined heat and power cycle system of claim 14, wherein the one or more locations in the second rankine cycle system comprises a location between the partial evaporator and the cascaded heat exchange unit.

17. The combined heat and power cycle system of claim 1, wherein the second rankine cycle system is configured to remove heat from the first heat source through a third heat exchanger.

18. The combined heat and power cycle system of claim 17, wherein the one or more locations in the second rankine cycle system comprises a location between the cascaded heat exchange unit and the third heat exchanger.

19. The combined heat and power cycle system of claim 17, wherein the one or more locations in the second rankine cycle system comprises a location between the third heat exchanger and an expander.

20. The combined heat and power cycle system of claim 1, wherein the first working fluid comprises steam.

21. The combined heat and power cycle system of claim 1, wherein the first working fluid comprises a first organic working fluid.

22. The combined heat and power cycle system of claim 1, wherein the first organic working fluid comprises cyclohexane, cyclopentane, thiophene, ketones, aromatics, or combinations thereof.

23. The combined heat and power cycle system of claim 1, wherein one or more locations in the first rankine cycle system comprises a location between an evaporator and an expander.

24. The combined heat and power cycle system of claim 1, wherein one or more locations in the first rankine cycle system comprises a location between an expander and the cascaded heat exchange unit.

25. The combined heat and power cycle system of claim 1, wherein the at least one heat exchanger is selectively activated and deactivated depending on the amount of heat required for heating the third fluid.

26. The combined heat and power cycle system of claim 1, wherein the first rankine cycle system and the second rankine cycle system are selectively activated and deactivated depending on the amount of power required.

27. A combined heat and power cycle system including at least two integrated organic rankine cycle systems, the combined heat and power cycle system comprising:

a combustion engine comprising one heat source comprising 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 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 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; and

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; and

at least one heat exchanger disposed at one or more locations in the first rankine cycle system; second rankine cycle system, or combinations thereof, wherein the first working fluid, second working fluid, or combinations thereof are circulatable in heat exchange relationship with a third fluid through the at least one heat exchanger for heating the third fluid.

28. The combined heat and power cycle system of claim 27, wherein the third fluid comprises water, or water mixed with anti-corrosive agent, or water mixed with anti-freezing agent.

29. The combined heat and power cycle system of claim 27, wherein the first organic rankine cycle system further comprises an evaporator coupled to the engine exhaust unit.

30. The combined heat and power cycle system of claim 29, wherein the evaporator is coupled to the engine exhaust unit through a thermal oil heat exchanger, an exhaust economizer, or combinations thereof.

31. The combined heat and power cycle system of claim 27, wherein the one or more locations in the first rankine cycle system comprises one or more locations between the evaporator and the thermal oil heat exchanger, the exhaust economizer, or combinations thereof.

32. The combined heat and power cycle system of claim 27, wherein the second rankine cycle system comprises a condenser 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.

33. The combined heat and power cycle system of claim 27, wherein the at least one heat exchanger is selectively activated and deactivated depending on the amount of heat required for heating the third fluid.

34. The combined heat and power cycle system of claim 27, wherein the first organic rankine cycle system and the second organic rankine cycle system are selectively activated and deactivated depending on the amount of power required.

35. A combined heat and power cycle system including at least two integrated rankine cycle systems, the combined heat and power cycle system comprising:

a second rankine cycle system 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; and

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; wherein the second rankine cycle is configured to preheat and/or partially evaporate the second working fluid before entering the cascaded heat exchange unit;

at least one heat exchanger disposed at one or more locations in the first rankine cycle system; second rankine cycle system, or combinations thereof; wherein the first working fluid, second working fluid, or combinations thereof are circulatable in heat exchange relationship with a third fluid through the at least one heat exchanger for heating the third fluid.

36. The combined heat and power cycle system of claim 36, wherein the third fluid comprises water, or water mixed with anit-corrosive agent, or water mixed with anti-freezing agent.