U.S. patent application number 11/243654 was filed with the patent office on 2007-10-25 for power recovery and energy conversion systems and methods of using same.
This patent application is currently assigned to TAS Ltd.. Invention is credited to John David Penton, Tom L. Pierson.
Application Number | 20070245733 11/243654 |
Document ID | / |
Family ID | 38618147 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070245733 |
Kind Code |
A1 |
Pierson; Tom L. ; et
al. |
October 25, 2007 |
POWER RECOVERY AND ENERGY CONVERSION SYSTEMS AND METHODS OF USING
SAME
Abstract
In various illustrative examples, the system may include heat
recovery heat exchangers, one or more turbines or expanders, a
desuperheater heat exchanger, a condenser heat exchanger, a
separator, an accumulator, and a liquid circulating pump, etc. In
one example, a bypass desuperheater control valve may be employed.
The system comprises a first heat exchanger adapted to receive a
heating stream from a heat source after passing through a second
heat exchanger and a second portion of a working fluid, wherein,
the second portion of working fluid is converted to a hot liquid
via heat transfer. An economizer heat exchanger that is adapted to
receive a first portion of the working fluid and the hot discharge
vapor from at least one turbine may also be provided. The first and
second portions of the working fluid are recombined in a first flow
mixer after passing through the economizer heat exchanger and first
heat exchanger, respectively. A second heat exchanger is provided
that receives the working fluid from the first flow mixer and a hot
heating stream from a heat source and convert the working fluid to
a hot vapor. The hot vapor from the second heat exchanger is
supplied to at least one turbine after passing through a separator
designed to insure no liquid enters the said at least one turbine
or expander. The hot, high pressure vapor is expanded in the
turbine to produce mechanical power on a shaft and is discharged as
a hot, low pressure vapor.
Inventors: |
Pierson; Tom L.; (Sugar
Land, TX) ; Penton; John David; (Pasadena,
TX) |
Correspondence
Address: |
WILLIAMS, MORGAN & AMERSON
10333 RICHMOND, SUITE 1100
HOUSTON
TX
77042
US
|
Assignee: |
TAS Ltd.
|
Family ID: |
38618147 |
Appl. No.: |
11/243654 |
Filed: |
October 5, 2005 |
Current U.S.
Class: |
60/651 ;
60/645 |
Current CPC
Class: |
F01K 25/08 20130101 |
Class at
Publication: |
060/651 ;
060/645 |
International
Class: |
F01K 13/00 20060101
F01K013/00; F01K 25/08 20060101 F01K025/08 |
Claims
1. A system, comprising: a flow divider adapted to receive a
working fluid and divide said working fluid into at least first and
second portions; a first heat exchanger adapted to receive a hot
heating stream from a heat source after said hot heating stream
passes through a second heat exchanger and said first portion of a
working fluid, wherein, when the first portion of said working
fluid is passed through the first heat exchanger, the first portion
of said working fluid is converted to a first hot liquid stream via
heat transfer with said hot heating stream from said heat source;
an economizer heat exchanger adapted to receive a hot vapor
discharged from at least one turbine and said second portion of
said working fluid, wherein, when the second portion of said
working fluid is passed through the economizer heat exchanger, the
second portion of said working fluid is converted to a second hot
liquid stream via heat transfer with said hot vapor discharged from
said at least one turbine; a first flow mixer adapted to receive at
least said first hot liquid stream and said second hot liquid
stream and discharge said at least first hot liquid stream and said
second hot liquid stream as a combined hot liquid working fluid; a
second heat exchanger adapted to receive a hot heating stream from
a heat source and said combined hot liquid working fluid, wherein,
when the combined hot liquid working fluid is passed through the
second heat exchanger, the combined hot liquid working fluid is
converted to a hot vapor via heat transfer with said hot heating
stream from said heat source; at least one separator adapted to
receive said hot vapor from said second heat exchanger and separate
said hot vapor into its liquid and gaseous phases for the purpose
of preventing liquid from entering said at least one turbine; at
least one liquid control valve to relieve said liquid from said at
least one separator, wherein said at least one turbine is adapted
to receive said hot vapor from said separator and produce
rotational, mechanical power at a shaft that is adapted to transmit
said power to at least one device adapted to receive said power; a
second flow mixer that is adapted to receive and combine said vapor
discharged from said at least one turbine after said vapor passes
through said economizer heat exchanger and a fluid from the
discharge of said liquid control valve into a single stream to be
condensed; a condenser heat exchanger that is adapted to receive
said single stream to be condensed and a cooling fluid, wherein the
temperature of said single stream to be condensed is reduced via
heat transfer with said cooling fluid; a liquid accumulator that is
adapted to receive said cooled working fluid, provide storage for
said cooled working fluid, and provide a surge volume for said
system; and, at least one pump that is adapted to circulate said
cooled working fluid to said first heat exchanger and said
economizer heat exchanger via said flow divider.
2. The system of claim 1 wherein said working fluid enters said
second heat exchanger as a supercritical liquid and via heat
transfer with the fluid from the heat source changes state from a
supercritical liquid to a supercritical vapor.
3. The system of claim 1 wherein said cooling fluid for said
condenser heat exchanger comprises at least one of a liquid and a
gas.
4. The system of claim 1 wherein said cooling fluid for said
condenser heat exchanger is a partially or fully vaporized liquid
as it passes through said condenser heat exchanger.
5. The system of claim 1 wherein said condenser heat exchanger is
adapted to condense the exhaust vapor from said at least one
turbine or expander to a liquid at a temperature between
approximately 0-250.degree. F.
6. The system of claim 1, wherein said working fluid is R-123 or
one of its derivatives and said fluid from said heat source has a
temperature of between approximately 450-1500.degree. F., the
maximum temperature of the working fluid is between approximately
363-700.degree. F., and wherein said pump is adapted to operate at
a discharge pressure greater than approximately 550 psia.
7. The system of claim 1, wherein said working fluid is R-134A or
one of its derivatives and said fluid from said heat source has a
temperature of between approximately 275-1500.degree. F., the
maximum temperature of the working fluid is between approximately
214-650.degree. F., and wherein said pump is adapted to operate at
a discharge pressure greater than approximately 600 psia.
8. The system of claim 1, wherein said working fluid is methyl
alcohol (methanol) or one of its derivatives and said fluid from
said heat source has a temperature of between approximately
500-2500.degree. F., the maximum temperature of the working fluid
is between approximately 463-963.degree. F., and wherein said pump
is adapted to operate at a discharge pressure greater than
approximately 1070 psia.
9. The system of claim 1, wherein said working fluid is bromine and
said fluid from said heat source has a temperature of between
approximately 500-2500.degree. F., the maximum temperature of the
working fluid is between approximately 592-1092.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 1500 psia.
10. The system of claim 1, wherein said working fluid is carbon
tetrachloride and said fluid from said heat source has a
temperature of between approximately 600-2500.degree. F., the
maximum temperature of the working fluid is between approximately
542-1042.degree. F., and wherein said pump is adapted to operate at
a discharge pressure greater than approximately 1000 psia.
11. The system of claim 1, wherein said working fluid is ethyl
alcohol or one of its derivatives and said fluid from said heat
source has a temperature of between approximately 500-2500.degree.
F., the maximum temperature of the working fluid is between
approximately 470-970.degree. F., and wherein said pump is adapted
to operate at a discharge pressure greater than approximately 920
psia.
12. The system of claim 1, wherein said working fluid is R-150A and
said fluid from said heat source has a temperature of between
approximately 500-2500.degree. F., the maximum temperature of the
working fluid is between approximately 482-982.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 730 psia.
13. The system of claim 1, wherein said working fluid is thiophene
and said fluid from said heat source has a temperature of between
approximately 600-2500.degree. F., the maximum temperature of the
working fluid is between approximately 583-1083.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 730 psia.
14. The system of claim 1, wherein said working fluid is a mixture
of hydrocarbons containing ten or fewer carbon atoms per molecule,
said fluid from said heat source has a temperature of between
approximately 400-2500.degree. F., the maximum temperature of the
working fluid is between approximately 400-1000.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 300 psia.
15. The system of claim 1, wherein said at least one turbine drives
at least one electrical generator to produce electrical power.
16. The system of claim 1, wherein said at least one turbine drives
at least one compressor.
17. The system of claim 1, wherein said at least one turbine drives
said at least one pump.
18. The system of claim 1, wherein said at least one turbine drives
at least one electrical generator to produce electrical power and
drives said at least one pump.
19. A system, comprising: a flow divider adapted to receive a
working fluid and divide said working fluid into at least three
portions; a first heat exchanger adapted to receive a hot heating
stream from a heat source after said hot heating stream passes
through a second heat exchanger and a first portion of a working
fluid, wherein, when the first portion of said working fluid is
passed through the first heat exchanger, the first portion of said
working fluid is converted to a first hot liquid stream via heat
transfer with said heating stream from said heat source; an
economizer heat exchanger adapted to receive a hot vapor discharged
from at least one turbine and a second portion of said working
fluid, wherein, when the second portion of said working fluid is
passed through the economizer heat exchanger, the second portion of
said working fluid is converted to a second hot liquid stream via
heat transfer from the heat contained in said hot vapor discharged
from at least one turbine; a bypass desuperheater liquid control
valve to regulate the flow of a third portion of said working fluid
to a second flow mixer or desuperheater; a first flow mixer adapted
to receive said first hot liquid stream and said second hot liquid
stream and discharge said first and second hot liquid streams as a
combined hot liquid working fluid stream; said second heat
exchanger being adapted to receive said hot heating stream from
said heat source and said combined hot liquid working fluid,
wherein, when the combined hot liquid working fluid is passed
through the second heat exchanger, the combined hot liquid working
fluid is converted to a vapor via heat transfer with said hot
heating stream from said heat source; at least one separator
adapted to receive said hot vapor from said second heat exchanger
and separate said hot vapor into its liquid and gaseous phases for
the purpose of preventing liquid from entering said at least one
turbine; at least one liquid control valve to relieve said liquid
from said at least one separator, wherein said at least one turbine
is adapted to receive said hot vapor and produce rotational,
mechanical power at a shaft that is adapted to transmit said power
to at least one device adapted to receive said power; a second flow
mixer that is adapted to receive and combine said vapor discharged
from said at least one turbine after said vapor passes through said
economizer heat exchanger, a fluid from the discharge of said
liquid control valve, and said third portion of the working fluid
from said bypass desuperheater liquid control valve into a single
stream to be condensed; a condenser heat exchanger that is adapted
to receive said single stream to be condensed and a cooling fluid,
wherein the temperature of said single stream to be condensed is
reduced via heat transfer with said cooling fluid; a liquid
accumulator that is adapted to receive said cooled working fluid,
provide storage for said cooled working fluid, and provide a surge
volume for said system; and, at least one pump that is adapted to
circulate said cooled working fluid to said first heat exchanger,
said economizer heat exchanger, and said second fluid mixer or
desuperheater via said bypass desuperheater liquid control valve
via said flow divider.
20. The system of claim 19, wherein said working fluid enters said
second heat exchanger as a supercritical liquid and via heat
transfer with the fluid from the heat source changes state from a
supercritical liquid to a supercritical vapor.
21. The system of claim 19, wherein said cooling fluid for said
condenser heat exchanger comprises at least one of a liquid and a
gas.
22. The system of claim 19, wherein said cooling fluid for said
condenser heat exchanger is a partially or fully vaporized liquid
as it passes through said condenser heat exchanger.
23. The system of claim 19, wherein said condenser heat exchanger
is adapted to condense the exhaust vapor from said at least one
turbine or expander to a liquid at a temperature between
approximately 0-250.degree. F.
24. The system of claim 19, wherein said working fluid is R-123 or
one of its derivatives and said fluid from said heat source has a
temperature of between approximately 450-1500.degree. F., the
maximum temperature of the working fluid is between approximately
363-700.degree. F., and wherein said pump is adapted to operate at
a discharge pressure greater than approximately 550 psia.
25. The system of claim 19, wherein said working fluid is R-134A or
one of its derivatives and said fluid from said heat source has a
temperature of between approximately 275-1500.degree. F., the
maximum temperature of the working fluid is between approximately
214-650.degree. F., and wherein said pump is adapted to operate at
a discharge pressure greater than approximately 600 psia.
26. The system of claim 19, wherein said working fluid is methyl
alcohol (methanol) or one of its derivatives and said fluid from
said heat source has a temperature of between approximately
500-2500.degree. F., the maximum temperature of the working fluid
is between approximately 463-963.degree. F., and wherein said pump
is adapted to operate at a discharge pressure greater than
approximately 1070 psia.
27. The system of claim 19, wherein said working fluid is bromine
and said fluid from said heat source has a temperature of between
approximately 500-2500.degree. F., the maximum temperature of the
working fluid is between approximately 592-1092.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 1500 psia.
28. The system of claim 19, wherein said working fluid is carbon
tetrachloride and said fluid from said heat source has a
temperature of between approximately 600-2500.degree. F., the
maximum temperature of the working fluid is between approximately
542-1042.degree. F., and wherein said pump is adapted to operate at
a discharge pressure greater than approximately 1000 psia.
29. The system of claim 19, wherein said working fluid is ethyl
alcohol or one of its derivatives and said fluid from said heat
source has a temperature of between approximately 500-2500.degree.
F., the maximum temperature of the working fluid is between
approximately 470-970.degree. F., and wherein said pump is adapted
to operate at a discharge pressure greater than approximately 920
psia.
30. The system of claim 19, wherein said working fluid is R-150A
and said fluid from said heat source has a temperature of between
approximately 500-2500.degree. F., the maximum temperature of the
working fluid is between approximately 482-982.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 730 psia.
31. The system of claim 19, wherein said working fluid is thiophene
and said fluid from said heat source has a temperature of between
approximately 600-2500.degree. F., the maximum temperature of the
working fluid is between approximately 583-1083.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 730 psia.
32. The system of claim 19, wherein said working fluid is a mixture
of hydrocarbons containing ten or fewer carbon atoms per molecule,
said fluid from said heat source has a temperature of between
approximately 400-2500.degree. F., the maximum temperature of the
working fluid is between approximately 400-1000.degree. F., and
wherein said pump is adapted to operate at a discharge pressure
greater than approximately 300 psia.
33. The system of claim 19, wherein said at least one turbine
drives at least one electrical generator to produce electrical
power.
34. The system of claim 19, wherein said at least one turbine
drives at least one compressor.
35. The system of claim 19, wherein said at least one turbine
drives said at least one pump.
36. The system of claim 19, wherein said at least one turbine
drives at least one electrical generator to produce electrical
power and drives said at least one pump.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to heat recovery for
the purpose of electrical or mechanical power generation.
Specifically, the present invention is directed to various systems
and methods for the conversion of heat of any quality into
mechanical or electrical power.
[0003] 2. Description of the Related Art
[0004] In general, there is a constant drive to increase the
operating efficiency of heat and power recovery systems. By
increasing the efficiency of such systems, capital costs may be
reduced, more power may be generated and there may be a reduction
of possible adverse impacts on the environment, e.g., a reduction
in the amount of waste heat that must ultimately be absorbed by the
environment. In other industrial processes, an excess amount of
heat may be generated as a byproduct of the process. In many cases,
such waste heat is normally absorbed by the environment through the
use of waste heat rejection devices such as cooling towers.
[0005] There are several systems employed in various industries to
produce useful work from a heat source. Such systems may including
the following:
[0006] Heat Recovery Steam Generators (HRSG)--Typically, waste heat
from gas turbines or other, similar, high quality heat sources is
recovered using steam at multiple temperatures and pressures.
Multiple operating levels are required because the
temperature-enthalpy profile is not linear. That is, such prior art
systems involve isothermal (constant temperature) boiling as the
working fluid, i.e. water, is converted from a liquid to a vapor
state. Various embodiments of the present invention eliminate the
need for multiple levels and simplify the process while having the
capability to recover more heat and to economically recover heat
from a much lower quality heat source.
[0007] Rankine Cycle--The classic Rankine cycle is utilized in
conjunction with HRSGs to produce power. This process is complex
and requires either multiple steam turbines or a multistage steam
turbine, feed water heaters, steam drums, pumps, etc. The methods
and systems of the present invention are significantly less complex
while being more effective than systems employing the Rankine
cycle.
[0008] Organic Rankine Cycle--Similar to the classic Rankine cycle,
an Organic Rankine cycle utilizes a low temperature working fluid
such as isoButane or isoPentane in place of steam in the classic
cycle. The system remains complex and is highly inefficient at low
operating temperature differences.
[0009] Kalina Cycle--Dr. Kalina's cycle is a next generation
enhancement to the Rankine cycle utilizing a binary fluid mixture,
typically water and ammonia. Water and ammonia are utilized at
different concentrations in various portions of the process to
extend the temperature range potential of the cycle and to allow
higher efficiencies than are possible in the Rankine cycle. The
methods and systems of the present invention simplify the process
while having the capability to recover more heat and to recover
heat from a low quality heat source.
[0010] The system depicted in FIG. 5 is an example of a prior art
system for heat recovery. The system comprises two heat recovery
heat exchangers 120 and 121, two turbines (expanders) 122 and 124,
and a reheater heat exchanger 123. The prior art system may or may
not have a separate gas cooler 125 and condenser 126. The
subcritical working fluid 102 enter the first heat recovery heat
exchanger 120 at approximately the condensing temperature from a
condenser 126. The liquid 102 is heated via heat transfer with the
discharged hot fluid 114 from the reheater heat exchanger 123 and
is discharged as either a wet or dry vapor 103 after boiling either
partially or completely in heat recovery heat exchanger 120. The
working fluid 103 is further heated in the second heat recovery
heat exchanger 121 to a dry vapor 104 via heat transfer with the
hot heat source 112 and is supplied to the inlet of the first
turbine 122. In at least some cases, the vapor 104 is at a
temperature near or slightly above its critical temperature but
well below its critical pressure. The hot vapor 104 is expanded in
turbine 122 and exits as a hot vapor 105. The hot vapor 105 is
introduced into a reheater heat exchanger 123 where is heated
(reheated) by the hot heating fluid 113 discharged from the second
heat recovery heat exchanger 121 via heat transfer. The reheated
working fluid 106 is then supplied to the inlet of the second
turbine 124 wherein it is expanded and discharged as a hot,
typically dry and highly superheated, vapor 107. The discharged
vapor 107 from the second turbine 124 may or may not be cooled in a
gas cooler 125 before being condensed in a condenser heat exchanger
126.
[0011] In the prior art system of FIG. 5, the subcritical working
fluid 102 enter the first heat recovery heat exchanger 120 at
approximately the condensing temperature from a condenser 126. Said
liquid 102 is heated via heat transfer with the discharged hot
fluid 114 from the reheater heat exchanger 123 and is discharged as
either a wet or dry vapor 103 after boiling either partially or
completely in heat recovery heat exchanger 120. Said working fluid
103 is further heated in the second heat recovery heat exchanger
121 to a dry vapor 104 via heat transfer with the hot heat source
112 and is supplied to the inlet of the first turbine 122. In the
most preferred embodiment the vapor 104 is at a temperature near or
slightly above its critical temperature but well below its critical
pressure. The hot vapor 104 is expanded in turbine 122 and exits as
a hot vapor 105. Such hot vapor 105 is introduced into a reheater
heat exchanger 123 where is heated (reheated) by the hot heating
fluid 113 discharged from the second heat recovery heat exchanger
121 via heat transfer. The reheated working fluid 106 is then
supplied to the inlet of the second turbine 124 wherein it is
expanded and discharged as a hot, typically dry and highly
superheated, vapor 107. The discharged vapor 107 from the second
turbine 124 may or may not be cooled in a gas cooler 125 before
being condensed in a condenser heat exchanger 126.
[0012] The four largest weaknesses of the prior art system are a)
the vapor 107 discharged from the second turbine 124 is
significantly superheated and thereby the system of FIG. 5 fails to
recover a portion of the valuable heat, b) the system utilizes a
subcritical working fluid which limits the efficiency of the heat
recovery in the heat recovery heat exchangers 120 and 121 due to
the non-linearity of the temperature-enthalpy profile in said
exchangers, c) the system generates unnecessary entropy further
reducing its output in accordance with the Second Law of
Thermodynamics, and d) the complexity of the system having multiple
turbines and multiple heat recovery heat exchangers is reflected in
an increased cost of the system for a given capacity recovery heat
exchanger(s) are usually the largest costs in a system of the
type.
[0013] The following patents may be descriptive of various aspects
of the prior art: U.S. Pat. No. 5,557,936 to Drnevich; U.S. Pat.
No. 5,029,444 to Kalina; U.S. Pat. No. 5,440,882 to Kalina; U.S.
Pat. No. 5,095,708 to Kalina; U.S. Pat. No. 5,572,871 to Kalina;
Japanese Patent S53-132638A to Nakahara and Fujiwara; U.S. Pat. No.
6,195,997 to Lewis; U.S. Pat. No. 4,577,112 to Smith; U.S. Pat. No.
6,857,268 to Stinger and Mian; each of which are hereby
incorporated by reference.
[0014] In general, what is desired are systems and methods for
improving the efficiencies of various heat conversion and power
generation systems and systems and methods for utilizing waste heat
sources to improve operating efficiencies of various power and
industrial systems. The present invention is directed to various
systems and methods that may solve, or at least reduce, some or all
of the aforementioned problems.
SUMMARY OF THE INVENTION
[0015] The following presents a simplified summary of the invention
in order to provide a basic understanding of some aspects of the
invention. This summary is not an exhaustive overview of the
invention. It is not intended to identify key or critical elements
of the invention or to delineate the scope of the invention. Its
sole purpose is to present some concepts in a simplified form as a
prelude to the more detailed description that is discussed
later.
[0016] The present invention is generally directed to various
systems and methods for producing mechanical power from a heat
source. In various illustrative examples, the devices employed in
practicing the present invention may include at least two heat
recovery heat exchangers, at least one turbine or an expander, a
desuperheater heat exchanger, an economizer heat exchanger, a
condenser heat exchanger, an accumulator, a separator, and a liquid
circulating pump, etc.
[0017] In one illustrative embodiment, the system comprises a first
heat exchanger adapted to receive a heating stream from a heat
source after passing through a second heat exchanger and a second
portion of a working fluid, wherein, when the second portion of the
working fluid is passed through the first heat exchanger, the
second portion of working fluid is converted to a hot liquid via
heat transfer from the heat contained in the heating stream from
the heat source after passing through a second heat exchanger. The
system is further comprised of an economizer heat exchanger adapted
to receive a first portion of the working fluid and the hot
discharge vapor from at least one turbine. The first and second
portions of the working fluid are recombined in a first flow mixer
after passing through the economizer heat exchanger and first heat
exchanger, respectively. The system is further comprised of a
second heat exchanger adapted to receive the working fluid from the
first flow mixer and a hot heating stream from a heat source and
convert the working fluid to a hot vapor. The hot vapor from the
second heat exchanger is supplied to at least one turbine or
expander after passing through a separator designed to insure no
liquid enters said at least one turbine. The hot, high pressure
vapor is expanded in the turbine to produce mechanical power on a
shaft and is discharged as a hot, low pressure vapor. The hot vapor
is then routed back to the economizer heat exchanger and then to a
second flow mixer (which may function as a desuperheater in some
cases) where the hot vapor is mixed with the liquid discharged from
the separator. The system further comprises a condenser heat
exchanger that is adapted to receive the exhaust vapor from the
turbine after passing through the economizer heat exchanger and
mixing with the liquid from the separator and a cooling fluid
circulated by a cooling fluid pump. The system is further comprised
of an accumulator vessel to receive the condensed liquid from the
condenser and meter said condensate to a liquid working fluid
circulating pump that is adapted to circulate the working fluid to
a flow divider. The system is finally comprised of a flow divider
that is adapted to split the working fluid into at least two
portions, at least one that is supplied to an economizer heat
exchanger and at least one that is supplied to a first heat
exchanger.
[0018] In another illustrative embodiment, the system comprises a
first heat exchanger adapted to receive a heating stream from a
heat source after passing through a second heat exchanger and a
second portion of a working fluid, wherein, the second portion of
the working fluid is passed through the first heat exchanger, the
second portion of working fluid is converted to a hot liquid via
heat transfer from the heat contained in the heating stream from
the heat source after passing through a second heat exchanger. The
system is further comprised of an economizer heat exchanger adapted
to receive a first portion of the working fluid and the hot
discharge vapor from at least one turbine. The system is further
comprised of a second flow mixer or desuperheater adapted to
receive a third portion of the working fluid via a fluid bypass
control valve. The first and second portions of the working fluid
are recombined in a first flow mixer after passing through the
economizer heat exchanger and first heat exchanger, respectively.
The system is further comprised of a second heat exchanger adapted
to receive the working fluid from the first flow mixer and a hot
heating stream from a heat source and heat the working fluid to a
hot vapor via heat transfer. The hot vapor from the second heat
exchanger is supplied to at least one turbine or expander after
passing through a separator designed to insure no liquid enters
said at least one turbine or expander. The hot, high pressure vapor
is expanded in the turbine to produce mechanical power on a shaft
and is discharged as a hot, low pressure vapor. The hot vapor is
then routed back to the economizer heat exchanger and then to a
second flow mixer (which may function as a desuperheater) where the
hot vapor is mixed with the liquid discharged from the separator
and a third portion of the working fluid from the flow divider. The
system further comprises a condenser heat exchanger that is adapted
to receive the exhaust vapor from the turbine or expander after
passing through the economizer heat exchanger and mixing with the
liquids from the separator and the flow divider and a cooling fluid
circulated by a cooling fluid pump. The system is further comprised
of an accumulator vessel to receive the condensed liquid from the
condenser and meter said condensate to a liquid working fluid
circulating pump that is adapted to circulate the working fluid to
a flow divider. The system is finally comprised of a flow divider
that is adapted to split the working fluid into at least three
portions, at least one that is supplied to an economizer heat
exchanger, at least one supplied to a second flow mixer, and at
least one that is supplied to a first heat exchanger.
[0019] In yet another illustrative embodiment, the system comprises
a first heat exchanger adapted to receive a heating stream from a
heat source after passing through a second heat exchanger and a
second portion of a working fluid, wherein, when the second portion
of the working fluid is passed through the first heat exchanger,
the second portion of working fluid is converted to a hot liquid
via heat transfer from the heat contained in the heating stream
from the heat source after passing through a second heat exchanger.
The system is further comprised of an economizer heat exchanger
adapted to receive a first portion of the working fluid and the hot
discharge vapor from at least one turbine. The first and second
portions of the working fluid are recombined in a first flow mixer
after passing through the economizer heat exchanger and first heat
exchanger, respectively. The system is further comprised of a
second heat exchanger adapted to receive the working fluid from the
first flow mixer and a hot heating stream from a heat source and
convert the working fluid to a hot vapor. The hot vapor from the
second heat exchanger is supplied to at least one turbine or
expander after passing through a separator designed to insure no
liquid enters said at least one turbine or expander. The hot, high
pressure vapor is expanded in the turbine or expander to produce
mechanical power on a shaft and is discharged as a hot, low
pressure vapor. The hot vapor is then routed back to the economizer
heat exchanger and then to a second flow mixer where the hot vapor
is mixed with the liquid discharged from the separator. The system
further comprises a condenser heat exchanger that is adapted to
receive the exhaust vapor from the turbine or expander after
passing through the economizer heat exchanger and mixing with the
liquid from the separator and a gaseous cooling media such as air.
The system is further comprised of an accumulator vessel to receive
the condensed liquid from the condenser and meter said condensate
to a liquid working fluid circulating pump that is adapted to
circulate the working fluid to a flow divider. The system is
finally comprised of a flow divider that is adapted to split the
working fluid into at least two portions, at least one that is
supplied to an economizer heat exchanger and at least one that is
supplied to a first heat exchanger.
[0020] In a fourth illustrative embodiment, the system comprises a
first heat exchanger adapted to receive a heating stream from a
heat source after passing through a second heat exchanger and a
second portion of a working fluid, wherein, the second portion of
the working fluid is passed through the first heat exchanger, the
second portion of working fluid is converted to a hot liquid via
heat transfer from the heat contained in the heating stream from
the heat source after passing through a second heat exchanger. The
system is further comprised of an economizer heat exchanger adapted
to receive a first portion of the working fluid and the hot
discharge vapor from at least one turbine or one expander. The
system is further comprised of a second flow mixer adapted to
receive a third portion of the working fluid via a fluid bypass
control valve. The first and second portions of the working fluid
are recombined in a first flow mixer after passing through the
economizer heat exchanger and first heat exchanger, respectively.
The system is further comprised of a second heat exchanger adapted
to receive the working fluid from the first flow mixer and a hot
heating stream from a heat source and heat the working fluid to a
hot vapor via heat transfer. The hot vapor from the second heat
exchanger is supplied to at least one turbine after passing through
a separator designed to insure no liquid enters the said at least
one turbine or expander. The hot, high pressure vapor is expanded
in the turbine or expander to produce mechanical power on a shaft
and is discharged as a hot, low pressure vapor. The hot vapor is
then routed back to the economizer heat exchanger and then to a
second flow mixer where the hot vapor is mixed with the liquid
discharged from the separator and a third portion of the working
fluid from the flow divider. The system further comprises a
condenser heat exchanger that is adapted to receive the exhaust
vapor from the turbine or expander after passing through the
economizer heat exchanger and mixing with the liquids from the
separator and the flow divider and a gaseous cooling media such as
air. The system is further comprised of an accumulator vessel to
receive the condensed liquid from the condenser and meter said
condensate to a liquid working fluid circulating pump that is
adapted to circulate the working fluid to a flow divider. The
system is finally comprised of a flow divider that is adapted to
split the working fluid into at least three portions, at least one
that is supplied to an economizer heat exchanger, at least one
supplied to a second flow mixer, and at least one that is supplied
to a first heat exchanger.
[0021] In all of the illustrative examples, the condenser heat
exchanger might be adapted to receive any one or a plurality of
cooling fluids such as water from a cooling tower; water from a
river or stream; water from a pond, lake, bay, or other freshwater
source; seawater from a bay, canal, channel, sea, ocean, or other
source; chilled water; fresh air; chilled air; a liquid process
stream, e.g. propane; a gaseous process stream, e.g. nitrogen; or
other heat sink such as a ground source cooling loop comprised of a
plurality of buried pipes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention may be understood by reference to the
following description taken in conjunction with the accompanying
drawings, in which like reference numerals identify like elements,
and in which:
[0023] FIG. 1 is a schematic diagram of one illustrative embodiment
of the present invention employing a working fluid circulating
pump, a flow divider, two heat recovery heat exchangers, an
economizer heat exchanger, a first flow mixer, a separator, a
turbine or expander, a liquid control valve, a second flow
mixer/desuperheater, a liquid cooled condenser heat exchanger, an
accumulator, a vent/charge valve, and a cooling liquid circulating
pump;
[0024] FIG. 2 is a schematic diagram of one illustrative embodiment
of the present invention employing a working fluid circulating
pump, a flow divider, two heat recovery heat exchangers, an
economizer heat exchanger, a first flow mixer, a separator, a
turbine or expander, a liquid control valve, a liquid desuperheater
feed bypass flow control valve, a second flow mixer/desuperheater,
a liquid cooled condenser heat exchanger, an accumulator, a
vent/charge valve, and a cooling liquid circulating pump;
[0025] FIG. 3 is a schematic diagram of one illustrative embodiment
of the present invention employing a working fluid circulating
pump, a flow divider, two heat recovery heat exchangers, an
economizer heat exchanger, a first flow mixer, a separator, a
turbine or expander, a liquid control valve, a second flow
mixer/desuperheater, a gas cooled condenser heat exchanger, an
accumulator, and a vent/charge valve;
[0026] FIG. 4 is a schematic diagram of one illustrative embodiment
of the present invention employing a working fluid circulating
pump, a flow divider, two heat recovery heat exchangers, an
economizer heat exchanger, a first flow mixer, a separator, a
turbine or expander, a liquid control valve, a liquid desuperheater
feed bypass flow control valve, a second flow mixer/desuperheater,
a gas cooled condenser heat exchanger, an accumulator, and a
vent/charge valve; and
[0027] FIG. 5 is a schematic diagram of one illustrative embodiment
of the prior art employed as an Organic Rankine Cycle with two
turbines or expanders and one reheat.
[0028] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0029] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0030] The present invention will now be described with reference
to the attached drawings which are included to describe and explain
illustrative examples of the present invention. The words and
phrases used herein should be understood and interpreted to have a
meaning consistent with the understanding of those words and
phrases by those skilled in the relevant art. No special definition
of a term or phrase, i.e., a definition that is different from the
ordinary and customary meaning as understood by those skilled in
the art, is intended to be implied by consistent usage of the term
or phrase herein. To the extent that a term or phrase is intended
to have a special meaning, i.e. a meaning other than that
understood by skilled artisans, such a special definition will be
expressly set forth in the specification in a definitional manner
that directly and unequivocally provides the special definition for
the term or phrase. Moreover, various streams or conditions may be
referred to with terms such as "hot," "cold," "cooled, "warm,"
etc., or other like terminology. Those skilled in the art will
recognize that such terms reflect conditions relative to another
process stream, not an absolute measurement of any particular
temperature.
[0031] The present invention is generally related to pending
allowed U.S. patent application Ser. No. 10/616,074, now U.S. Pat.
No. ______. That pending application is hereby incorporated by
reference in its entirety.
[0032] One illustrative embodiment of the present invention will
now be described with reference to FIG. 1. As shown therein, a high
pressure, liquid working fluid 2 enters a flow divider 26 and is
split into two portions 3,10. A first portion 3 of the working
fluid enters an economizer heat exchanger 27 adapted to receive a
hot vapor discharge 8 from a turbine or expander 31 and the first
portion 3 of the working fluid is heated via heat transfer with the
hot vapor 8 and exits as a hot liquid 4. For purposes of the
present application, the term "turbine" will be understood to
include both turbines and expanders or any device wherein useful
work is generated by expanding a high pressure gas within the
device. A second portion 10 of the working fluid enters a first
heat exchanger 37 that is adapted to receive a hot heating stream
20 from a heat source (via line 19) after passing through a second
heat exchanger 29. The second portion 10 of the working fluid is
heated via heat transfer with the hot heating stream 20 in the
first heat exchanger 37. The hot heating stream 20 discharges from
the first heat exchanger 37 as a cool vapor 21 that is near or
below its dew point. The second portion 10 of the working fluid
exits the first heat exchanger as a hot liquid 11. The hot liquid 4
and the hot liquid 11 are mixed in a first flow mixer 28 and
discharged as a combined hot liquid stream 5. The combined hot
liquid stream 5 is introduced into a second heat exchanger 29 that
is adapted to receive a heating stream 19 and exits as a
superheated vapor 6 due to heat transfer with a hot fluid, either a
gas, a liquid, or a two-phase mixture of gas and liquid entering at
19 and exiting at 20. The vapor 6 may be a subcritical or
supercritical vapor.
[0033] The heat exchangers 27, 29, and 37 may be any type of heat
exchanger capable of transferring heat from one fluid stream to
another fluid stream. For example, the heat exchangers 27, 29, and
37 may be shell-and-tube heat exchangers, a plate-fin-tube coil
type of exchangers, bare tube or finned tube bundles, welded plate
heat exchangers, etc. Thus, the present invention should not be
considered as limited to any particular type of heat exchanger
unless such limitations are expressly set forth in the appended
claims.
[0034] The source of the hot heating stream 19 for the second heat
exchanger 29 may either be a waste heat source (from any of a
variety of sources) or heat may intentionally be supplied to the
system, e.g. by a gas burner, a fuel oil burner, or the like. In
one illustrative embodiment, the source of the hot heating stream
19 for the second heat exchanger 29 is a waste heat source such as
the exhaust from an internal combustion engine (e.g. a
reciprocating diesel engine), a combustion gas turbine, a
compressor, or an industrial or manufacturing process. However, any
heat source of sufficient quantity and temperature may be utilized
if it can be obtained economically. In some cases, the first and
second heat exchangers 37, 29 may be referred to either as "waste
heat recovery heat exchangers," indicating that the source of the
heating stream 19 is from what would otherwise be a waste heat
source, although the present invention is not limited to such
situations, or "heat recovery heat exchangers" indicating that the
source of the heating stream 19 is from what would be any heat
source.
[0035] In one embodiment, the vapor 6 then enters a separator 30
that is designed to protect the turbine 31 from any liquid that
might be entrained in the vapor 6 and to separate the normally dry,
highly superheated vapor 6 into a dry vapor 7 and a liquid
component 12. The liquid component 12 is routed away from the
separator 30 via a liquid control valve 38 to prevent accumulation
of the liquid in the separator 30. The vapor 7 then enters the
turbine (expander) 31. The vapor 7 is expanded in the turbine
(expander) 31 and the design of the turbine 31 converts kinetic and
potential energy of the dry vapor 7 into mechanical energy in the
form of torque on an output shaft 32. Any type of commercially
available turbine suited for use in the systems described herein
may be employed, e.g. an expander, a turbo-expander, a power
turbine, etc. The shaft horsepower available on the shaft 32 of the
turbine 31 can be used to produce power by driving one or more
generators, compressors, pumps, or other mechanical devices, either
directly or indirectly. Several illustrative embodiments of how
such useful power may be used are described further in the
application. Additionally, as will be recognized by those skilled
in the art after a complete reading of the present application, a
plurality of turbines 31 or heat recovery heat exchangers 29 or 37
may be employed with the system depicted in FIG. 1.
[0036] The low pressure, high temperature discharge 8 from the
turbine 31 is routed to an economizer heat exchanger 27 that is
adapted to receive the first portion 3 of the liquid working fluid.
The economizer heat exchanger 27 cools the hot vapor 8 via heat
transfer with the first portion 3 of the liquid working fluid and
discharges the hot vapor as a cool vapor 9 at or near its dew
point. The cool vapor 9 is routed to a second flow mixer or
desuperheater 33 that is adapted to receive the cooled vapor 9 and
a hot incidental fluid 13 from the liquid control valve 38. The hot
incidental fluid 13, intermittently discharged during startup,
shutdown, or upset conditions may be either a liquid or a vapor
containing both a liquid and a gas and would not normally be a gas
exclusively. After the combination of the cooled vapor 9 and the
incidental fluid 13 in the second fluid mixer or desuperheater 33
the combined stream 14 is routed to a condenser heat exchanger 34
that is adapted to receive a cooling fluid 23. The condenser 34
condenses the slightly superheated to partially wet, low pressure
vapor 14 and condenses it to the liquid state using water,
seawater, or other liquid or boiling fluids 23 which might be
circulated by a low pressure liquid circulating pump 39 which
provides the necessary motive force to circulate the cooling fluid
from point 22 to point 24. The condenser 34 may be utilized to
condense the hot working fluid from a vapor 14 to a liquid 15 at a
temperature ranging from approximately 50-250.degree. F.
[0037] The condensed liquid 15 is introduced into an accumulator
drum 35. The drum 35 may serve several purposes, such as, for
example: (a) the design of the drum 35 ensures that the pump 25 has
sufficient head to avoid cavitation; (b) the design of the drum 35
ensures that the supply of liquid 18, 1 to the pump 25 is steady;
(c) the design of the drum 35 ensures that the pump 25 will not be
run dry; (d) the design of the drum 35 provides an opportunity to
evacuate any non-condensable vapors from the system through a vent
valve 36 via lines 16, 17; (e) the design of the drum 35 allows for
the introduction of process liquid into the system; and (f) the
design of the drum 35 allows for the introduction of makeup
quantities of the process liquid in the event that a small amount
of operating fluid is lost. The high pressure discharge 2 of the
pump 25 is fed to the first flow divider 26. The pump 25 may be any
type of commercially available pump sufficient to meet the pumping
requirements of the systems disclosed herein. In various
embodiments, the pump 25 may be sized such that the discharge
pressure of the working fluid ranges from approximately 300 psia to
1500 psia. In the most preferred embodiment, the selection of the
discharge pressure of the pump 25 is dependent on the critical
pressure of the working fluid 2 and should be approximately 5 psia
to 500 psia greater than the critical pressure of the working fluid
2 although pressures lower than the critical pressure may be
utilized with a reduction in the efficiency of the system.
[0038] In the illustrative embodiment depicted in FIG. 1, the
working fluid enters the first heat recovery heat exchanger 37 and
the economizer heat exchanger 27 as a cool, high pressure liquid
and, after being recombined, leaves as a hot liquid 5. The working
fluid 5 then enters the second heat recovery heat exchanger 29 and
leaves as a superheated vapor 6. The high pressure, superheated
vapor 6 is then expanded through a turbine 31 to produce mechanical
power after passing through a separator 30 and split into a dry
vapor 7 and a liquid 12. The vapor 8 exiting the turbine 31 is at
low pressure and in the superheated state and the vapor 8 is passed
through the economizer heat exchanger 27 and the second fluid mixer
33. In some applications, the second fluid mixer 33 may function as
a desuperheater. After the second fluid mixer 33, the vapor is then
introduced into the condenser heat exchanger 34 which may be water
cooled, air cooled, evaporatively cooled, or used as a heat source
for district heating, domestic hot water, or similar heating load.
The condensed low pressure liquid 15 is fed to the suction of a
pump 25 via drum 35 and is pumped to the high pressure required for
the first heat recovery heat exchanger 37 and the economizer heat
exchanger 27.
[0039] The present invention may employ a single component working
fluid that may be comprised of, for example, ammonia (NH3), bromine
(Br2), carbon tetrachloride (CCl4), ethyl alcohol or ethanol
(CH3CH2OH, C2H6O), furan (C4H4O), hexafluorobenzene or
perfluorobenzene (C6F6), hydrazine (N2H4), methyl alcohol or
methanol (CH3OH), monochlorobenzene or chlorobenzene or
chlorobenzol or benzine chloride (C6H5Cl), n-pentane or normal
pentane (nC5), i-hexane or isohexane (iC5), pyridene or azabenzene
(C5H5N), refrigerant 11 or freon 11 or CFC-11 or R-11 or
trichlorofluoromethane (CCl3F), refrigerant 12 or freon 12 or R-12
or dichlorodifluoromethane (CCl2F2), refrigerant 21 or freon 21 or
CFC-21 or R-21 (CHCl2F), refrigerant 30 or freon 30 or CFC-30 or
R-30 or dichloromethane or methylene chloride or methylene
dichloride (CH2Cl2), refrigerant 115 or freon 115 or CFC-115 or
R-115 or chloropentafluoroethane or monochloropentafluoroethane,
refrigerant 123 or freon 123 or HCFC-123 or R-123 or 2,2
dichloro-1,1,1-trifluoroethane, refrigerant 123a or freon 123a or
HCFC-123a or R-123a or 1,2-dichloro-1,1,2-trifluoroethane,
refrigerant 123b1 or freon 123b1 or HCFC-123b1 or R-123b1 or
halothane or 2-bromo-2-chloro-1,1,1-trifluoroethane, refrigerant
134A or freon 134A or HFC-134A or R-134A or
1,1,1,2-tetrafluoroethane, refrigerant 150A or freon 150A or
CFC-150A or R-150A or dichloroethane or ethylene dichloride
(CH3CHCl2), thiophene (C4H4S), toluene or methylbenzene or
phenylmethane or toluol (C7H8), water (H2O), etc. In some
applications, the working fluid may be comprised of multiple
components. For example, one or more of the compounds identified
above may be combined or with a hydrocarbon fluid, e.g. isobutene,
etc. Further, several simple hydrocarbons compounds may be combined
such as isopentane, toluene, and hexane to create a working fluid.
In the context of the present application, reference may be made to
the use of methyl alcohol or methanol as the working fluid and to
provide certain illustrative examples. However, after a complete
reading of the present application, those skilled in the art will
recognize that the present invention is not limited to any
particular type of working fluid or refrigerant. Thus, the present
invention should not be considered as limited to any particular
working fluid unless such limitations are clearly set forth in the
appended claims.
[0040] In the present invention, as the working fluid 5 passes
through the second heat recovery heat exchanger 29, it changes from
a liquid state to a vapor state in a non-isothermal process using
an approximately linear temperature-enthalpy profile, i.e., the
slope of the temperature-enthalpy curve does not change
significantly even though the working fluid changes state from a
subcooled liquid to a superheated vapor. The slope of the
temperature-enthalpy graph may vary depending upon the application.
Moreover, the temperature-enthalpy profile may not be linear over
the entire range of the curve.
[0041] The temperature-enthalpy profile of the working fluid of the
present invention is fundamentally different from other systems.
For example, a temperature-enthalpy profile for a typical Rankine
cycle undergoes one or more essentially isothermal (constant
temperature) boiling processes as the working fluid changes from a
liquid state to a vapor state. Other systems, such as a Kalina
cycle, may exhibit a more non-isothermal conversion of the working
fluid from a liquid state to a vapor state, but such systems employ
binary component working fluids, such as ammonia and water.
[0042] The non-isothermal process used in practicing aspects of the
present invention is very beneficial in that it provides a greater
heat capacity that may be recaptured when the vapor is cooled back
to a liquid. That is, due to the higher temperatures involved in
such a non-isothermal process, the working fluid, in the
superheated vapor state, contains much more useable heat energy
that may be recaptured and used for a variety of purposes. Further,
the nearly linear temperature-enthalpy profile allows the exiting
temperature of the (waste) heat source to approach more closely to
the working fluid temperature 2,10 entering the first heat recovery
heat exchanger 37.
[0043] By way of example, with reference to FIG. 1, in one
illustrative embodiment where the working fluid is methyl alcohol
or methanol, the temperature of the working fluid at point 2 may be
between approximately 50-250.degree. F. at approximately 1120 psia
to 1220 psia at the discharge of the pump 25. The working fluid at
point 15 may be at a pressure of approximately 1 psia to 92 psia at
the discharge of the condenser 34 (see FIG. 1) for a system
pressure ratio of between approximately between twelve to one
(12:1) and one thousand two hundred and twenty to one (1220:1). In
one particularly illustrative embodiment, the pressure ratio would
be as large as practical. The temperature of the methanol working
fluid 6 at the exit of the heat exchanger 29 may be approximately
500-1000.degree. F. or more. The temperature of the methanol
working fluid 8 at the exit of the turbine 31 may be between
approximately 90.degree. F. (at a pressure of approximately 3 psia)
and 670.degree. F. (at a pressure of approximately 92 psia). The
temperature of the methanol working fluid 8 at the exit of the
turbine 31 may be superheated by between approximately 10.degree.
F. (at a pressure of approximately 8 psia when the vapor 7 entering
the turbine 31 is at 650.degree. F.) and approximately 415.degree.
F. (at a pressure of 92 psia when the vapor 7 entering the turbine
31 is at 1000.degree. F.). The amount of superheat at 8 is
functionally related to the pressure ratio of the system, the
efficiency of the turbine 31, the thermodynamic properties of the
working fluid, the degree of superheat at 7 entering the turbine
31, the flow ratio of the streams 3,10 exiting the flow divider 26,
and the hot heating stream discharge temperature 21. In one
particularly illustrative embodiment of the present invention, the
temperature of the working fluid at point 8 exiting the turbine 31
will be selected, along with other parameters, to produce a
condenser 34 inlet temperature as close as possible to the dew
point of the working fluid 14 at the conditions entering the
condenser 34. The present embodiment will allow large amounts of
superheat at 7 and at 8 and still remain more efficient than
previous, related art.
[0044] In another illustrative embodiment where the working fluid
is bromine, the temperature of the working fluid at point 2 may be
between approximately 50-250.degree. F. at approximately 1540 psia
at the discharge of the pump 25. The working fluid at point 15 may
be at a pressure of approximately 11 psia at the discharge of the
condenser 34 for a system pressure ratio of approximately one
hundred and forty to one (140:1). The temperature of the bromine
working fluid 6 at the exit of the heat exchanger 29 may be
approximately 650-1000.degree. F. The temperature of the bromine
working fluid 8 at the exit of the turbine 31 may be approximately
130.degree. F. at a pressure of approximately 13 psia.
[0045] In another illustrative embodiment where the working fluid
is carbon tetrachloride, the temperature of the working fluid at
point 2 may be between approximately 50-250.degree. F. at
approximately 690 psia at the discharge of the pump 25. The working
fluid at point 15 may be at a pressure of approximately 6 psia at
the discharge of the condenser 34 for a system pressure ratio of
approximately one hundred thirty to one (130:1). The temperature of
the carbon tetrachloride working fluid 6 at the exit of the heat
exchanger 29 may be approximately 550-770.degree. F. The
temperature of the carbon tetrachloride working fluid 8 at the exit
of the turbine 31 may be approximately 155-400.degree. F. at a
pressure of approximately 8 psia.
[0046] In another illustrative embodiment where the working fluid
is ethyl alcohol or ethanol, the temperature of the working fluid
at point 2 may be between approximately 50-250.degree. F. at
approximately 1000 psia at the discharge of the pump 25. The
working fluid at point 15 may be at a pressure of approximately 4
psia at the discharge of the condenser 34 for a system pressure
ratio of approximately two hundred and fifty to one (250:1). The
temperature of the ethyl alcohol or ethanol working fluid 6 at the
exit of the heat exchanger 29 may be approximately 500-800.degree.
F. The temperature of the ethyl alcohol or ethanol working fluid 8
at the exit of the turbine 31 may be approximately 135-400.degree.
F. at a pressure of approximately 6 psia.
[0047] In another illustrative embodiment where the working fluid
is R-150A, the temperature of the working fluid at point 2 may be
between approximately 50-250.degree. F. at approximately 770 psia
at the discharge of the pump 25. The working fluid at point 15 may
be at a pressure of approximately 11 psia at the discharge of the
condenser 34 for a system pressure ratio of approximately seventy
to one (70:1). The temperature of the R-150A working fluid 6 at the
exit of the heat exchanger 29 may be approximately 500-705.degree.
F. The temperature of the R-150A working fluid 8 at the exit of the
turbine 31 may be approximately 155-400.degree. F. at a pressure of
approximately 13 psia.
[0048] In another illustrative embodiment where the working fluid
is thiophene, the temperature of the working fluid at point 2 may
be between approximately 50-250.degree. F. at approximately 900
psia at the discharge of the pump 25. The working fluid at point 15
may be at a pressure of approximately 4.5 psia at the discharge of
the condenser 34 for a system pressure ratio of approximately two
hundred to one (200:1). The temperature of the thiophene working
fluid 6 at the exit of the heat exchanger 29 may be approximately
600-730.degree. F. The temperature of the thiophene working fluid 8
at the exit of the turbine 31 may be approximately 220-400.degree.
F. at a pressure of approximately 6.5 psia.
[0049] In another illustrative embodiment where the working fluid
is a mixture of hydrocarbon compounds, the temperature of the
working fluid at point 2 may be between approximately
50-250.degree. F. at approximately 576 psia at the discharge of the
pump 25. The working fluid at point 15 may be at a pressure of
approximately 36 psia at the discharge of the condenser 34 for a
system pressure ratio of approximately sixteen to one (16:1). The
temperature of the mixture of hydrocarbon compounds working fluid 6
at the exit of the heat exchanger 29 may be approximately
520-655.degree. F. The temperature of the mixture of hydrocarbon
compounds working fluid 8 at the exit of the turbine 31 may be
approximately 375-550.degree. F. at a pressure of approximately 38
psia. For this illustrative example, the mixture of hydrocarbons on
a molar basis is approximately 10% propane, 10% isobutane, 10%
isopentane, 20% hexane, 20% heptane, 10% octane, 10% nonane, and
10% decane. This mixture is one of an infinite number of possible
mixtures that might be selected to suit specific needs of a
particular embodiment and is in no way representative of the only
or best solution.
[0050] The methods and systems described herein may be most
effective for pressure ratios greater than three to one (3:1) and
the pressure ratio is determined by the physical characteristics of
the working fluid being utilized. The specific embodiments of this
invention significantly improve the efficiency of the specific
embodiments of this invention over the previous inventions of the
prior art and of this specific art to allow usage at almost any
pressure ratio. The specific selection of the low cycle pressure is
determined by the condensing pressure of the working fluid and will
be, typically, the saturation pressure of the working fluid at
between approximately 0-250.degree. F., depending on the cooling
medium or condenser heat exchanger type and the ambient temperature
or ultimate heat sink temperature. The specific selection of the
high cycle pressure is determined by the thermodynamic properties
of the working fluid plus a margin, as a minimum, and by cycle
efficiency, pump power consumption, and maximum component design
pressures as a maximum.
[0051] In another illustrative embodiment of the present invention
a system substantially similar to FIG. 1 will now be described with
reference to FIG. 2. As shown therein, a high pressure, liquid
working fluid 2 enters a flow divider 26 and is split into three
portions 3,10,40. A first portion 3 of the working fluid enters the
economizer heat exchanger 27 that is adapted to receive the hot
vapor discharge 8 from the turbine 31 wherein the working fluid 3
is heated via heat transfer with the hot vapor 8 and exits as a hot
liquid 4. A second portion 10 of the working fluid enters the first
heat exchanger 37 that is adapted to receive the hot heating stream
20 from the heat source (via line 19) after passing through a
second heat exchanger 29, wherein the working fluid 10 is heated to
a hot liquid 11 via heat transfer with the hot heating stream 20,
that ultimately discharges from the first heat exchanger 37 as a
cool vapor 21 near or below its dew point. A third portion 40 of
the working fluid is routed to a second fluid mixer 33 (which may
function as a desuperheater in some cases) that is adapted to
receive a portion of the working fluid 42, a cool vapor 9 from the
economizer heat exchanger 27, and the incidental liquid 13 from the
separator 30. The hot liquid 4 and the hot liquid 11 are mixed in a
first flow mixer 28 and discharged as a combined hot liquid stream
5. The combined hot liquid stream 5 is introduced into the second
heat exchanger 29 that is adapted to receive the heating stream 19
and exits as a superheated vapor 6 due to heat transfer with a hot
fluid, either a gas, a liquid, or a two-phase mixture of gas and
liquid entering at 19 and exiting at 20. The vapor 6 may be a
subcritical or supercritical vapor.
[0052] The heat exchangers 27, 29, and 37 may be any type of heat
exchanger capable of transferring heat from one fluid stream to
another fluid stream. For example, the heat exchangers 27, 29, and
37 may be shell-and-tube heat exchangers, a plate-fin-tube coil
type of exchangers, bare tube or finned tube bundles, welded plate
heat exchangers, etc. Thus, the present invention should not be
considered as limited to any particular type of heat exchanger
unless such limitations are expressly set forth in the appended
claims.
[0053] The source of the hot heating stream 19 for the second heat
exchanger 29 may either be a waste heat source (from any of a
variety of sources) or heat may intentionally be supplied to the
system, e.g. by a gas burner, a fuel oil burner, or the like. In
one illustrative embodiment, the source of the hot heating stream
19 for the second heat exchanger 29 is a waste heat source such as
the exhaust from an internal combustion engine (e.g. a
reciprocating diesel engine), a combustion gas turbine, a
compressor, or an industrial or manufacturing process. However, any
heat source of sufficient quantity and temperature may be utilized
if it can be obtained economically. In some cases, the first and
second heat exchangers 37, 29 may be referred to either as "waste
heat recovery heat exchangers," indicating that the source of the
heating stream 19 is from what would otherwise be a waste heat
source, although the present invention is not limited to such
situations, or "heat recovery heat exchangers" indicating that the
source of the heating stream 19 is from what would be any heat
source.
[0054] In one embodiment, the vapor 6 then enters the separator 30
that is designed to protect the turbine 31 from any liquid that
might be in the vapor 6 and to separate the normally dry, highly
superheated vapor 6 into a dry vapor 7 and a liquid component 12.
The liquid component 12 is routed away from the separator 30 via a
liquid control valve 38 to prevent accumulation of the liquid in
the separator 30. The vapor 7 then enters the turbine (expander)
31. The vapor 7 is expanded in the turbine (expander) 31 and the
design of the turbine 31 converts kinetic and potential energy of
the dry vapor 7 into mechanical energy in the form of torque on an
output shaft 32. Any type of commercially available turbine suited
for use in the systems described herein may be employed, e.g. an
expander, a turbo-expander, a power turbine, etc. The shaft
horsepower available on the shaft 32 of the turbine 31 can be used
to produce power by driving one or more generators, compressors,
pumps, or other mechanical devices, either directly or indirectly.
Several illustrative embodiments of how such useful power may be
used are described further in the application. Additionally, as
will be recognized by those skilled in the art after a complete
reading of the present application, a plurality of turbines 31 or
heat recovery heat exchangers 29 or 37 may be employed with the
system depicted in FIG. 2.
[0055] The low pressure, high temperature discharge 8 from the
turbine 31 is routed to the economizer heat exchanger 27 that is
adapted to receive the first portion 3 of the liquid working fluid.
The economizer heat exchanger 27 cools the hot vapor 8 via heat
transfer with the first portion 3 of the liquid working fluid and
discharges the hot vapor as a cool vapor 9 at or near its dew
point. The cool vapor 9 is routed to a second fluid mixer or
desuperheater 33 that is adapted to receive the cooled vapor 9, a
hot incidental fluid 13 from the liquid control valve 38, and a
portion of the cool, liquid working fluid 42 after the liquid flows
through a liquid bypass control valve 41 and a line 40. The hot
incidental fluid 13, intermittently discharged during startup,
shutdown, or upset conditions may be either a liquid or a vapor
containing both a liquid and a gas and would not normally be a gas
exclusively. After the combination of the cooled vapor 9, the
incidental fluid 13, and the working fluid 42 in the second fluid
mixer or desuperheater 33 the combined stream 14 is routed to a
condenser heat exchanger 34 that is adapted to receive a cooling
fluid 23. The condenser 34 condenses the slightly superheated to
partially wet, low pressure vapor 14 to the liquid state using
water, seawater, or other liquid or boiling fluids 23 which might
be circulated by a low pressure liquid circulating pump 39 which
provides the necessary motive force to circulate the cooling fluid
from point 22 to point 24. The condenser 34 may be utilized to
condense the hot working fluid from a vapor 14 to a liquid 15 at a
temperature ranging from approximately 0-250.degree. F.
[0056] The condensed liquid 15 is introduced into an accumulator
drum 35. The drum 35 may serve several purposes, such as, for
example: (a) the design of the drum 35 ensures that the pump 25 has
sufficient head to avoid cavitation; (b) the design of the drum 35
ensures that the supply of liquid 18, 1 to the pump 25 is steady;
(c) the design of the drum 35 ensures that the pump 25 will not be
run dry; (d) the design of the drum 35 provides an opportunity to
evacuate any non-condensable vapors from the system through a vent
valve 36 via lines 16, 17; (e) the design of the drum 35 allows for
the introduction of process liquid into the system; and (f) the
design of the drum 35 allows for the introduction of makeup
quantities of process liquid in the event that a small amount of
operating fluid is lost. The high pressure discharge 2 of the pump
25 is fed to the first flow divider 26. The pump 25 may be any type
of commercially available pump sufficient to meet the pumping
requirements of the systems disclosed herein. In various
embodiments, the pump 25 may be sized such that the discharge
pressure of the working fluid ranges from approximately 300 psia to
1500 psia. In one particularly illustrative embodiment, the
selection of the discharge pressure of the pump 25 is dependent on
the critical pressure of the working fluid 2 and should be
approximately 5 psia to 500 psia greater than the critical pressure
of the working fluid 2 although pressures lower than the critical
pressure may be utilized with a reduction in the efficiency of the
system.
[0057] In the illustrative embodiment depicted in FIG. 2, the
working fluid enters the first heat recovery heat exchanger 37 and
the economizer heat exchanger 27 as a cool, high pressure liquid
and leaves as a hot liquid 5. The working fluid 5 then enters the
second heat recovery heat exchanger 29 and leaves as a superheated
vapor 6. The high pressure, superheated vapor 6 is then expanded
through a turbine 31 to produce mechanical power after passing
through a separator 30 and split into a dry vapor 7 and a liquid
12. The vapor 8 exiting the turbine 31 is at low pressure and in
the superheated state, and it is passed through the economizer heat
exchanger 27 and the second fluid mixer 33. After the second fluid
mixer 33, vapor is then introduced into the condenser heat
exchanger 34 which may be water cooled, air cooled, evaporatively
cooled, or used as a heat source for district heating, domestic hot
water, or similar heating load. The condensed low pressure liquid
15 is fed to the suction of a pump 25 via a drum 35 and is pumped
to the high pressure required for the first heat recovery heat
exchanger 37, the economizer heat exchanger 27 and the liquid
bypass valve 41.
[0058] As described above, the present invention may employ a
single component working fluid that may be comprised of any of the
previously mentioned or similar fluids. After a complete reading of
the present application, those skilled in the art will recognize
that the present invention is not limited to any particular type of
working fluid or refrigerant. Thus, the present invention should
not be considered as limited to any particular working fluid unless
such limitations are clearly set forth in the appended claims.
[0059] In another illustrative embodiment of the present invention
a system substantially similar to FIG. 1 will now be described with
reference to FIG. 3. As shown therein, a high pressure, liquid
working fluid 2 enters the flow divider 26 and is split into two
portions 3,10. A first portion 3 of the working fluid enters the
economizer heat exchanger 27 that is adapted to receive a hot vapor
discharge 8 from the turbine 31, wherein the working fluid 3 is
heated via heat transfer with the hot vapor 8 and exits as a hot
liquid 4. A second portion 10 of the working fluid enters the first
heat exchanger 37 that is adapted to receive the hot heating stream
20 from a heat source after passing through a second heat exchanger
29, wherein the working fluid 10 is heated to a hot liquid 11 via
heat transfer with the hot heating stream 20, that ultimately
discharges as a cool vapor 21 near or below its dew point. The hot
liquid 4 and the hot liquid 11 are mixed in the first flow mixer 28
and discharged as a combined hot liquid stream 5. The combined hot
liquid stream 5 is introduced into the second heat exchanger 29
that is adapted to receive the heating stream 19 and exits as a
superheated vapor 6 due to heat transfer with a hot fluid, either a
gas, a liquid, or a two-phase mixture of gas and liquid entering at
19 and exiting at 20. The vapor 6 may be a subcritical or
supercritical vapor.
[0060] The heat exchangers 27, 29, and 37 may be any type of heat
exchanger capable of transferring heat from one fluid stream to
another fluid stream. For example, the heat exchangers 27, 29, and
37 may be shell-and-tube heat exchangers, a plate-fin-tube coil
type of exchangers, bare tube or finned tube bundles, welded plate
heat exchangers, etc. Thus, the present invention should not be
considered as limited to any particular type of heat exchanger
unless such limitations are expressly set forth in the appended
claims.
[0061] The source of the hot heating stream 19 for the second heat
exchanger 29 may either be a waste heat source (from any of a
variety of sources) or heat may intentionally be supplied to the
system, e.g. by a gas burner, a fuel oil burner, or the like. In
one illustrative embodiment, the source of the hot heating stream
19 for the second heat exchanger 29 is a waste heat source such as
the exhaust from an internal combustion engine (e.g. a
reciprocating diesel engine), a combustion gas turbine, a
compressor, or an industrial or manufacturing process. However, any
heat source of sufficient quantity and temperature may be utilized
if it can be obtained economically. In some cases, the first and
second heat exchangers 37, 29 may be referred to either as "waste
heat recovery heat exchangers," indicating that the source of the
heating stream 19 is from what would otherwise be a waste heat
source, although the present invention is not limited to such
situations, or "heat recovery heat exchangers" indicating that the
source of the heating stream 19 is from what would be any heat
source.
[0062] In one embodiment, the vapor 6 then enters the separator 30
that is designed to protect the turbine 31 from any liquid that
might be in the vapor 6 and to separate the normally dry, highly
superheated vapor 6 into a dry vapor 7 and a liquid component 12.
The liquid component 12 is routed away from the separator 30 via
the liquid control valve 38 to prevent accumulation of the liquid
in the separator 30. The vapor 7 then enters the turbine (expander)
31. The vapor 7 is expanded in the turbine (expander) 31 and the
design of the turbine 31 converts kinetic and potential energy of
the dry vapor 7 into mechanical energy in the form of torque on an
output shaft 32. Any type of commercially available turbine suited
for use in the systems described herein may be employed, e.g. an
expander, a turbo-expander, a power turbine, etc. The shaft
horsepower available on the shaft 32 of the turbine 31 can be used
to produce power by driving one or more generators, compressors,
pumps, or other mechanical devices, either directly or indirectly.
Several illustrative embodiments of how such useful power may be
used are described further in the application. Additionally, as
will be recognized by those skilled in the art after a complete
reading of the present application, a plurality of turbines 31 or
heat recovery heat exchangers 29 or 37 may be employed with the
system depicted in FIG. 3.
[0063] The low pressure, high temperature discharge 8 from the
turbine 31 is routed to an economizer heat exchanger 27 adapted to
receive a first portion 3 of the liquid working fluid. The
economizer heat exchanger 27 cools the hot vapor 8 via heat
transfer with the first portion 3 of the liquid working fluid and
discharges the hot vapor as a cool vapor 9 at or near its dew
point. The cool vapor 9 is routed to a second fluid mixer or
desuperheater 33 that is adapted to receive the cooled vapor 9 and
a hot incidental fluid 13 from the liquid control valve 38. The hot
incidental fluid 13, intermittently discharged during startup,
shutdown, or upset conditions may be either a liquid or a vapor
containing both a liquid and a gas and would not normally be a gas
exclusively. After the combination of the cooled vapor 9 and the
incidental fluid 13 in the second fluid mixer or desuperheater 33
the combined stream 14 is routed to a condenser heat exchanger 43
adapted to be gas cooled. The condenser 43 condenses the slightly
superheated to partially wet, low pressure vapor 14 to the liquid
state using air, nitrogen, hydrogen, or other gas. The condenser 43
may be utilized to condense the hot working fluid from a vapor 14
to a liquid 15 at a temperature ranging from approximately
0-250.degree. F.
[0064] The condensed liquid 15 is introduced into an accumulator
drum 35. The drum 35 may serve several purposes, such as, for
example: (a) the design of the drum 35 ensures that the pump 25 has
sufficient head to avoid cavitation; (b) the design of the drum 35
ensures that the supply of liquid 18, 1 to the pump 25 is steady;
(c) the design of the drum 35 ensures that the pump 25 will not be
run dry; (d) the design of the drum 35 provides an opportunity to
evacuate any non-condensable vapors from the system through a vent
valve 36 via lines 16, 17; (e) the design of the drum 35 allows for
the introduction of process liquid into the system; and (f) the
design of the drum 35 allows for the introduction of makeup
quantities of liquid in the event that a small amount of operating
fluid is lost. The high pressure discharge 2 of the pump 25 is fed
to the first flow divider 26. The pump 25 may be any type of
commercially available pump sufficient to meet the pumping
requirements of the systems disclosed herein. In various
embodiments, the pump 25 may be sized such that the discharge
pressure of the working fluid ranges from approximately 300 psia to
1500 psia. In the most preferred embodiment, the selection of the
discharge pressure of the pump 25 is dependent on the critical
pressure of the working fluid 2 and should be approximately 5 psia
to 500 psia greater than the critical pressure of the working fluid
2 although pressures lower than the critical pressure may be
utilized with a reduction in the efficiency of the system.
[0065] In the illustrative embodiment depicted in FIG. 3, the
working fluid (3, 10) enters the first heat recovery heat exchanger
37 and the economizer heat exchanger 27 as a cool, high pressure
liquid and leaves (after being combined) as a hot liquid 5. The
working fluid 5 then enters the second heat recovery heat exchanger
29 and leaves as a superheated vapor 6. The high pressure,
superheated vapor 6 is then expanded through a turbine 31 to
produce mechanical power after passing through a separator 30 and
split into a dry vapor 7 and a liquid 12. The vapor 8 exiting the
turbine 31 is at low pressure and in the superheated state and is
passed through the economizer heat exchanger 27 and the second
fluid mixer 33. Thereafter, this vapor is then introduced into the
condenser heat exchanger 43 that is adapted to be gas cooled. The
condensed low pressure liquid 15 is fed to the suction of a pump 25
via a drum 35 and is pumped to the high pressure required for the
first heat recovery heat exchanger 37 and the economizer heat
exchanger 27.
[0066] After a complete reading of the present application, those
skilled in the art will recognize that the present invention is not
limited to any particular type of working fluid or refrigerant.
Thus, the present invention should not be considered as limited to
any particular working fluid unless such limitations are clearly
set forth in the appended claims.
[0067] In another illustrative embodiment of the present invention
a system substantially similar to FIG. 2 will now be described with
reference to FIG. 4. As shown therein, a high pressure, liquid
working fluid 2 enters a flow divider 26 and is split into three
portions 3,10,40. A first portion 3 of the working fluid enters the
economizer heat exchanger 27 that is adapted to receive a hot vapor
discharge 8 from a turbine 31, wherein the working fluid 3 is
heated via heat transfer with the hot vapor 8 and exits as a hot
liquid 4. A second portion 10 of the working fluid enters the first
heat exchanger 37 that is adapted to receive the hot heating stream
20 from the heat source 19 after passing through a second heat
exchanger 29, wherein the working fluid 10 is heated to a hot
liquid via heat transfer with the hot heating stream 20, that
ultimately discharges from the first heat exchanger 37 as a cool
vapor 21 near or below its dew point. A third portion 40 of the
working fluid is routed to a second fluid mixer 33 that is adapted
to receive a portion 40 of the working fluid 42, a cool vapor 9
from the economizer heat exchanger 27, and an incidental liquid 13
from the separator 30. The hot liquid 4 and the hot liquid 11 are
mixed in a first flow mixer 28 and discharged as a combined hot
liquid stream 5. The combined hot liquid stream 5 is introduced
into the second heat exchanger 29 that is adapted to receive the
heating stream 19 and exits as a superheated vapor 6 due to heat
transfer with a hot fluid, either a gas, a liquid, or a two-phase
mixture of gas and liquid entering at 19 and exiting at 20. The
vapor 6 may be a subcritical or supercritical vapor.
[0068] The heat exchangers 27, 29, and 37 may be any type of heat
exchanger capable of transferring heat from one fluid stream to
another fluid stream. For example, the heat exchangers 27, 29, and
37 may be shell-and-tube heat exchangers, a plate-fin-tube coil
type of exchangers, bare tube or finned tube bundles, welded plate
heat exchangers, etc. Thus, the present invention should not be
considered as limited to any particular type of heat exchanger
unless such limitations are expressly set forth in the appended
claims.
[0069] The source of the hot heating stream 19 for the second heat
exchanger 29 may either be a waste heat source (from any of a
variety of sources) or heat may intentionally be supplied to the
system, e.g. by a gas burner, a fuel oil burner, or the like. In
one illustrative embodiment, the source of the hot heating stream
19 for the second heat exchanger 29 is a waste heat source such as
the exhaust from an internal combustion engine (e.g. a
reciprocating diesel engine), a combustion gas turbine, a
compressor, or an industrial or manufacturing process. However, any
heat source of sufficient quantity and temperature may be utilized
if it can be obtained economically. In some cases, the first and
second heat exchangers 37, 29 may be referred to either as "waste
heat recovery heat exchangers," indicating that the source of the
heating stream 19 is from what would otherwise be a waste heat
source, although the present invention is not limited to such
situations, or "heat recovery heat exchangers" indicating that the
source of the heating stream 19 is from what would be any heat
source.
[0070] In one embodiment, the vapor 6 then enters the separator 30
that is designed to protect the turbine 31 from any liquid that
might be in the vapor 6 and to separate the normally dry, highly
superheated vapor 6 into a dry vapor 7 and a liquid component 12.
The liquid component 12 is routed away from the separator via a
liquid control valve 38 to prevent accumulation of the liquid in
the separator 30. The vapor 7 then enters the turbine (expander)
31. The vapor 7 is expanded in the turbine (expander) 31 and the
design of the turbine 31 converts kinetic and potential energy of
the dry vapor 7 into mechanical energy in the form of torque on an
output shaft 32. Any type of commercially available turbine suited
for use in the systems described herein may be employed, e.g. an
expander, a turbo-expander, a power turbine, etc. The shaft
horsepower available on the shaft 32 of the turbine 31 can be used
to produce power by driving one or more generators, compressors,
pumps, or other mechanical devices, either directly or indirectly.
Several illustrative embodiments of how such useful power may be
used are described further in the application. Additionally, as
will be recognized by those skilled in the art after a complete
reading of the present application, a plurality of turbines 31 or
heat recovery heat exchangers 29 or 37 may be employed with the
system depicted in FIG. 4.
[0071] The low pressure, high temperature discharge 8 from the
turbine 31 is routed to an economizer heat exchanger 27 that is
adapted to receive the first portion 3 of the liquid working fluid.
The economizer heat exchanger 27 cools the hot vapor 8 via heat
transfer with the first portion 3 of the liquid working fluid and
discharges the hot vapor as a cool vapor 9 at or near its dew
point. The cool vapor 9 is routed to a second fluid mixer 33 that
is adapted to receive the cooled vapor 9, a hot incidental fluid 13
from the liquid control valve 38, and a portion of the cool, liquid
working fluid 42 after the liquid flows through a liquid bypass
control valve 41 and a line 40. The hot incidental fluid 13,
intermittently discharged during startup, shutdown, or upset
conditions may be either a liquid or a vapor containing both a
liquid and a gas and would not normally be a gas exclusively. After
the combination of the cooled vapor 9, the incidental fluid 13, and
the working fluid 42 in the second fluid mixer or desuperheater 33
the combined stream 14 is routed to a condenser heat exchanger 43
that is adapted to be gas cooled. The condenser 43 condenses the
slightly superheated to partially wet, low pressure vapor 14 and
condenses it to the liquid state using air, nitrogen, hydrogen, or
other gas. The condenser 43 may be utilized to condense the hot
working fluid from a vapor 14 to a liquid 15 at a temperature
ranging from approximately 0-250.degree. F.
[0072] The condensed liquid 15 is introduced into an accumulator
drum 35. The drum 35 may serve several purposes, such as, for
example: (a) the design of the drum 35 ensures that the pump 25 has
sufficient head to avoid cavitation; (b) the design of the drum 35
ensures that the supply of liquid 18, 1 to the pump 25 is steady;
(c) the design of the drum 35 ensures that the pump 25 will not be
run dry; (d) the design of the drum 35 provides an opportunity to
evacuate any non-condensable vapors from the system through a vent
valve 36 via lines 16, 17; (e) the design of the drum 35 allows for
the introduction of process liquid into the system; and (f) the
design of the drum 35 allows for the introduction of makeup
quantities of process liquid in the event that a small amount of
operating fluid is lost. The high pressure discharge 2 of the pump
25 is fed to the first flow divider 26. The pump 25 may be any type
of commercially available pump sufficient to meet the pumping
requirements of the systems disclosed herein. In various
embodiments, the pump 25 may be sized such that the discharge
pressure of the working fluid ranges from approximately 300 psia to
1500 psia. In one particularly illustrative embodiment, the
selection of the discharge pressure of the pump 25 is dependent on
the critical pressure of the working fluid 2 and should be
approximately 5 psia to 500 psia greater than the critical pressure
of the working fluid 2 although pressures lower than the critical
pressure may be utilized with a reduction in the efficiency of the
system.
[0073] In the illustrative embodiment depicted in FIG. 4, the
working fluid enters the first heat recovery heat exchanger 37 and
the economizer heat exchanger 27 as a cool, high pressure liquid
and leaves as a hot liquid 5. The working fluid 5 then enters the
second heat recovery heat exchanger 29 and leaves as a superheated
vapor 6. The high pressure, superheated vapor 6 is then expanded
through a turbine 31 to produce mechanical power after passing
through a separator 30 and split into a dry vapor 7 and a liquid
12. The vapor 8 exiting the turbine 31 is at low pressure and in
the superheated state and it is passed through the economizer heat
exchanger 27 and the second fluid mixer 33. After the second fluid
mixer 33, this vapor is then introduced into the condenser heat
exchanger 43. The condensed low pressure liquid 15 is fed to the
suction of a pump 25 via a drum 35 and is pumped to the high
pressure required for the first heat recovery heat exchanger 37,
the economizer heat exchanger 27 and the liquid bypass valve
41.
[0074] As described above, the present invention may employ a
single component working fluid that may be comprised of any of the
previously mentioned or similar fluids. After a complete reading of
the present application, those skilled in the art will recognize
that the present invention is not limited to any particular type of
working fluid or refrigerant. Thus, the present invention should
not be considered as limited to any particular working fluid unless
such limitations are clearly set forth in the appended claims.
[0075] In one specific embodiment of the present invention, the
mechanical power available at the output shaft of the turbine may
be utilized directly or through a gearbox to provide mechanical
work to drive an electrical power generator to produce electrical
power either as a constant voltage and constant frequency AC source
or as a DC source which might be rectified to produce AC power at a
constant voltage and constant frequency.
[0076] In another specific embodiment, the mechanical power
available at the output shaft of the turbine may be utilized
directly or through a gearbox to provide mechanical work to drive
any combination of mechanical devices such as a compressor, a pump,
a wheel, a propeller, a conveyer, a fan, a gear, or any other
mechanical device(s) requiring or accepting mechanical power input.
Moreover, the present invention is not restricted to stationary
devices, as it may be utilized in or on an automobile, a ship, an
aircraft, a spacecraft, a train, or other non-stationary
vessel.
[0077] A specific byproduct of the method of the present invention
is an effective and dramatic reduction in the emissions of both
pollutants and greenhouse gases. This method may not require any
fuel nor does it generate any pollutants or greenhouse gases or any
other gases as byproducts. Any process to which this method may be
applied, such as a gas turbine or a diesel engine, will generate
significantly more power with no increase in fuel consumption or
pollution. The effect of this method is a net reduction in the
specific pollution generation rate on a mass per power produced
basis.
[0078] The present invention is generally directed to various
systems and methods for producing mechanical power from a heat
source. In various illustrative examples, the devices employed in
practicing the present invention may include heat recovery heat
exchangers, turbines or expanders, an economizer heat exchanger, a
desuperheater heat exchanger, a condenser heat exchanger, an
accumulator, a separator, and a liquid circulating pump, etc. In
one illustrative embodiment, the system comprises heat exchangers
adapted to receive a fluid from a heat source and a working fluid,
wherein, when the working fluid is passed through the first heat
exchanger, the working fluid is converted to a vapor via heat
transfer from the heat contained in the fluid from the heat source,
at least one turbine adapted to receive the vapor, and an
economizer heat exchanger adapted to receive exhaust vapor from the
turbine and a portion of the working fluid, wherein a temperature
of the working fluid is adapted to be increased via heat transfer
with the exhaust vapor from the turbine prior to the introduction
of the working fluid into the second heat exchangers. The system
further comprises a condenser heat exchanger that is adapted to
receive the exhaust vapor from the turbine after the exhaust vapor
has passed through the economizer heat exchanger and a cooling
fluid, wherein a temperature of the exhaust vapor is reduced via
heat transfer with the cooling fluid, and a pump that is adapted to
circulate the working fluid to the first and second heat exchanger
and the economizer heat exchanger.
[0079] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. For example, the process steps
set forth above may be performed in a different order. Furthermore,
no limitations are intended to the details of construction or
design herein shown, other than as described in the claims below.
It is therefore evident that the particular embodiments disclosed
above may be altered or modified and all such variations are
considered within the scope and spirit of the invention.
Accordingly, the protection sought herein is as set forth in the
claims below.
* * * * *