U.S. patent application number 12/413920 was filed with the patent office on 2010-09-30 for combined heat and power cycle system.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Gabor Ast, Thomas Johannes Frey, Pierre Sebastien Huck, Herbert Kopecek.
Application Number | 20100242476 12/413920 |
Document ID | / |
Family ID | 42782439 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100242476 |
Kind Code |
A1 |
Ast; Gabor ; et al. |
September 30, 2010 |
COMBINED HEAT AND POWER CYCLE SYSTEM
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.
Inventors: |
Ast; Gabor; (Garching,
DE) ; Frey; Thomas Johannes; (Ingolstadt, DE)
; Huck; Pierre Sebastien; (Munich, DE) ; Kopecek;
Herbert; (Hallbergmoos, DE) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY;GLOBAL RESEARCH
ONE RESEARCH CIRCLE, BLDG. K1-3A59
NISKAYUNA
NY
12309
US
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
42782439 |
Appl. No.: |
12/413920 |
Filed: |
March 30, 2009 |
Current U.S.
Class: |
60/645 ;
60/670 |
Current CPC
Class: |
F01K 25/10 20130101;
F01K 23/065 20130101; Y02E 20/14 20130101; F01K 23/04 20130101 |
Class at
Publication: |
60/645 ;
60/670 |
International
Class: |
F01K 13/00 20060101
F01K013/00; F01K 23/06 20060101 F01K023/06 |
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 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 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.
Description
BACKGROUND
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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
[0007] 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.
[0008] 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.
[0009] 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
[0010] 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:
[0011] 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;
[0012] 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;
[0013] 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;
[0014] 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;
[0015] 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;
[0016] 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
[0017] 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
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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.
* * * * *