U.S. patent number RE46,316 [Application Number 14/712,363] was granted by the patent office on 2017-02-21 for multi-level organic rankine cycle power system.
This patent grant is currently assigned to ORMAT TECHNOLOGIES, INC.. The grantee listed for this patent is ORMAT TECHNOLOGIES, INC.. Invention is credited to Lucien Bronicki, Uri Kaplan, Josef Sinai.
United States Patent |
RE46,316 |
Kaplan , et al. |
February 21, 2017 |
Multi-level organic rankine cycle power system
Abstract
A waste heat recovery system includes a high pressure turbine
and a low pressure turbine, in which the high pressure turbine
receives high pressure working fluid vapor, the low pressure
turbine receives low pressure working fluid vapor and the high
pressure turbine also supplies low pressure working fluid vapor to
the low pressure turbine. A recuperator receives working fluid
vapor from the low pressure turbine. The recuperator produces
heated condensate, at least a portion of which is provided to a
high pressure vaporizer. The high pressure vaporizer is configured
to receive from a high temperature heat source and produces high
pressure working vapor used to power the high pressure turbine. The
remaining condensed fluid is provided to a low pressure vaporizer
which is configured to receive heat from a low-temperature heat
source, thereby producing low pressure working fluid vapor used to
power the low pressure turbine.
Inventors: |
Kaplan; Uri (Soreq,
IL), Sinai; Josef (Or-Yehuda, IL),
Bronicki; Lucien (Yavne, IL) |
Applicant: |
Name |
City |
State |
Country |
Type |
ORMAT TECHNOLOGIES, INC. |
Reno |
NV |
US |
|
|
Assignee: |
ORMAT TECHNOLOGIES, INC. (Reno,
NV)
|
Family
ID: |
1000002134393 |
Appl.
No.: |
14/712,363 |
Filed: |
May 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
11736331 |
Nov 22, 2011 |
8061139 |
|
|
Reissue of: |
12457477 |
Jun 11, 2009 |
8438849 |
May 14, 2013 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01K
23/065 (20130101); F01K 23/10 (20130101); F01K
25/08 (20130101); F01K 7/18 (20130101); F01K
25/08 (20130101); F22B 1/1807 (20130101); F01K
23/065 (20130101); F01K 7/025 (20130101); Y02E
20/16 (20130101); Y02E 20/16 (20130101) |
Current International
Class: |
F01K
7/34 (20060101); F01K 23/04 (20060101); F01K
23/06 (20060101); F22B 1/18 (20060101); F01K
25/08 (20060101); F01K 7/18 (20060101); F01K
7/02 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International Search Authority, International Search Report,
Publication No. WO 2010/143046 A3 (Published Apr. 7, 2011); Search
completed Dec. 26, 2010. cited by applicant .
International Search Authority, International Search Report,
Publication No. WO 2010/143046 (Published Dec. 16, 2010); Search
completed Dec. 26, 2010. cited by applicant.
|
Primary Examiner: Kaufman; Joseph
Attorney, Agent or Firm: Nath, Goldberg & Meyer Meyer;
Jerald L.
Parent Case Text
RELATED APPLICATIONS
This application is a Continuation-in-Part Application of U.S.
patent application Ser. No. 11/736,331 filed on Apr. 17, 2007, the
contents of which are hereby incorporated in their entirety.
Claims
What is claimed is:
1. A waste heat recovery system utilizing a working fluid
comprising: a high pressure vapor turbine receiving high pressure
working fluid vapor and producing power and low pressure working
fluid vapor; a low pressure vapor turbine receiving said low
pressure working fluid vapor and producing power and expanded
working fluid vapor; a recuperator receiving said expanded working
fluid vapor and producing heat-depleted expanded working fluid
vapor; a condenser receiving said heat-depleted expanded working
fluid vapor and producing condensate, said condensate recycled to
said recuperator to produce heated condensate and said
heat-depleted expanded working fluid vapor; a first vaporizer
receiving a first portion of said heated condensate and configured
to receive heat from a low-temperature heat source, thereby
producing low pressure working fluid vapor; and a second vaporizer
receiving a second portion of said heated condensate and configured
to receive heat from a high-temperature heat source, thereby
producing said high pressure working fluid vapor.
2. The waste heat recovery system according to claim 1 wherein said
first vaporizer receives heat from said low-temperature heat source
through a further working fluid and said first vaporizer produces
heat-depleted further working fluid along with said low pressure
working fluid vapor.
3. The waste heat recovery system according to claim 2 wherein said
further working fluid is cooling water.
4. The waste heat recovery system according to claim 1 wherein said
second vaporizer receives heat from said high-temperature heat
source through a heat transfer fluid and said second vaporizer
produces heat-depleted heat transfer fluid along with said high
pressure working fluid vapor.
5. The waste heat recovery system according to claim 4 wherein said
heat transfer fluid is selected from the group consisting of
exhaust gases, a thermal oil, and a synthetic heat transfer
fluid.
6. The waste heat recovery system according to claim 4 further
comprising a preheater receiving said second portion of said heated
condensate and said heat-depleted heat transfer fluid and producing
further heat-depleted heat transfer fluid and further heated
condensate, said further heated condensate supplied to second
vaporizer.
7. The waste heat recovery system according to claim 1 wherein said
working fluid is selected from the group consisting of water,
alcohol, butane, iso-butane, n-pentane, iso-pentane, hexane,
iso-hexane, and mixtures thereof.
8. The waste heat recovery system according to claim 1 wherein said
low pressure working fluid vapor from said high pressure turbine
and said low pressure working fluid vapor from said first vaporizer
are combined prior to being supplied to said low pressure vapor
turbine.
9. The waste heat recovery system according to claim 1 wherein said
low pressure working fluid vapor from said high pressure turbine
and said low pressure working fluid vapor from said first vaporizer
are combined in said low pressure vapor turbine.
10. A waste heat recovery system utilizing a working fluid
comprising: a high pressure vapor turbine receiving high pressure
working fluid vapor and producing power and low pressure working
fluid vapor; a low pressure vapor turbine receiving said low
pressure working fluid vapor and producing power and expanded
working fluid vapor; a recuperator receiving said expanded working
fluid vapor and producing heat-depleted expanded working fluid
vapor; a condenser receiving said heat-depleted expanded working
fluid vapor and producing condensate, a first portion of said
condensate recycled to said recuperator to produce heated
condensate and said heat-depleted expanded working fluid vapor; a
first vaporizer receiving a second portion of said condensate and
configured to receive heat from a low-temperature heat source,
thereby producing low pressure working fluid vapor; and a second
vaporizer receiving said heated condensate and configured to
receive heat from a high-temperature heat source, thereby producing
said high pressure working fluid vapor.
11. The waste heat recovery system according to claim 10 wherein
said first vaporizer receives heat from said low-temperature heat
source through a first further working fluid and said first
vaporizer produces heat-depleted first further working fluid along
with said low pressure working fluid vapor.
12. The waste heat recovery system according to claim 11 wherein
said first further working fluid is cooling water.
13. The waste heat recovery system according to claim 10 wherein
said second vaporizer receives heat from said high-temperature heat
source through a heat transfer fluid and said second vaporizer
produces heat-depleted heat transfer fluid along with said high
pressure working fluid vapor.
14. The waste heat recovery system according to claim 13 wherein
said heat transfer fluid is selected from the group consisting of
exhaust gases, a thermal oil, and a synthetic heat transfer
fluid.
15. The waste heat recovery system according to claim 13 further
comprising a preheater receiving said heated condensate and said
heat-depleted heat transfer fluid and producing further
heat-depleted heat transfer fluid and further heated condensate,
said further heated condensate supplied to said second
vaporizer.
16. The waste heat recovery system according to claim 10 wherein
said working fluid is selected from the group consisting of water,
alcohol, butane, iso-butane, n-pentane, iso-pentane, hexane,
iso-hexane, and mixtures thereof.
17. The waste heat recovery system according to claim 10 wherein
said low pressure working fluid vapor from said high pressure
turbine and said low pressure working vapor from said first
vaporizer are combined prior to being supplied to said low pressure
vapor turbine.
18. A waste heat recovery system utilizing a working fluid
comprising: a high pressure vapor turbine receiving high pressure
working fluid vapor and producing power and expanded high pressure
working fluid vapor; a low pressure vapor turbine receiving low
pressure working fluid vapor and producing power and expanded low
pressure working fluid vapor; a condenser receiving said expanded
high pressure working fluid vapor and said expanded low pressure
working fluid vapor and producing condensate; a first vaporizer
receiving a first portion of said condensate and configured to
receive heat from a low-temperature heat source, thereby producing
said low pressure working fluid vapor; and a second vaporizer
receiving a second portion of said condensate and configured to
receive heat from a high-temperature heat source, thereby producing
said high pressure working fluid vapor.
19. The waste heat recovery system according to claim 18 wherein
said first vaporizer receives heat from said low-temperature heat
source through a further working fluid and said first vaporizer
produces heat-depleted further working fluid along with said low
pressure working fluid vapor.
20. The waste heat recovery system according to claim 19 wherein
said further working fluid is cooling water.
21. The waste heat recovery system according to claim 18 wherein
said second vaporizer receives heat from said high-temperature heat
source through a heat transfer fluid and said second vaporizer
produces heat-depleted heat transfer fluid along with said high
pressure working fluid vapor.
22. The waste heat recovery system according to claim 21 wherein
said heat transfer fluid is selected from the group consisting of
exhaust gases, a thermal oil, and a synthetic heat transfer
fluid.
23. The waste heat recovery system according to claim 21 further
comprising a preheater receiving said heated condensate and said
heat-depleted heat transfer fluid and producing further
heat-depleted heat transfer fluid and further heated condensate,
said further heated condensate supplied to said second
vaporizer.
24. The waste heat recovery system according to claim 18 wherein
said working fluid is selected from the group consisting of water,
alcohol, butane, iso-butane, n-pentane, iso-pentane, hexane,
iso-hexane, and mixtures thereof.
25. A waste heat recovery system utilizing a working fluid
comprising: a high pressure vapor turbine receiving high pressure
working fluid vapor and producing power and expanded high pressure
working fluid vapor; a recuperator receiving said expanded high
pressure working fluid vapor and producing heat-depleted expanded
high pressure working fluid vapor; a first condenser receiving said
heat-depleted expanded high pressure working fluid vapor and
producing first condensate, said first condensate recycled to said
recuperator to produce heated condensate and said heat-depleted
expanded high pressure working fluid vapor; a first vaporizer
receiving said heated condensate and configured to receive heat
from a high-temperature heat source, thereby producing said high
pressure working fluid vapor; a low pressure vapor turbine
receiving low pressure working fluid vapor and producing power and
expanded low pressure working fluid vapor; a second condenser
receiving said expanded low pressure working fluid vapor and
producing second condensate; a second vaporizer receiving said
second condensate and configured to receive heat from a
low-temperature heat source, thereby producing said low pressure
working fluid vapor; and a generator connected to said high
pressure vapor turbine and said low pressure vapor turbine for
producing power.
26. The waste heat recovery system according to claim 25 wherein
said second vaporizer receives heat from said low-temperature heat
source through a first further working fluid and said second
vaporizer produces heat-depleted first further working fluid along
with said low pressure working fluid vapor.
27. The waste heat recovery system according to claim 26 wherein
said first further working fluid is cooling water.
28. The waste heat recovery system according to claim 25 wherein
said first vaporizer receives heat from said high-temperature heat
source through a heat transfer fluid and said first vaporizer
produces heat-depleted heat transfer fluid along with said high
pressure working fluid vapor.
29. The waste heat recovery system according to claim 28 wherein
said heat transfer fluid is selected from the group consisting of
exhaust gases, a thermal oil, and a synthetic heat transfer
fluid.
30. The waste heat recovery system according to claim 28 further
comprising a preheater receiving said heated condensate and said
heat-depleted heat transfer fluid and producing further
heat-depleted heat transfer fluid and further heated condensate,
said further heated condensate supplied to said first
vaporizer.
31. The waste heat recovery system according to claim 25 wherein
said working fluid is selected from the group consisting of water,
alcohol, butane, iso-butane, n-pentane, iso-pentane, hexane,
iso-hexane, and mixtures thereof.
.Iadd.32. A waste heat recovery system utilizing a working fluid
comprising: a high pressure vapor turbine arranged to receive high
pressure working fluid vapor and to produce power and low pressure
working fluid vapor; a low pressure vapor turbine arranged to
receive said low pressure working fluid vapor and to produce power
and expanded working fluid vapor; a recuperator arranged to receive
said expanded working fluid vapor and to produce heat-depleted
expanded working fluid vapor; a condenser for receiving said
heat-depleted expanded working fluid vapor and producing
condensate, said condensate being recycled to said recuperator to
produce heated condensate and said heat-depleted expanded working
fluid vapor; a first vaporizer arranged to receive a portion of
said condensate and configured to receive heat from a
low-temperature heat source, thereby producing low pressure working
fluid vapor; a second vaporizer arranged to receive a further
portion of condensate and configured to receive heat from a
high-temperature heat source, thereby producing said high pressure
working fluid vapor..Iaddend.
.Iadd.33. A waste heat recovery system utilizing a working fluid
according to claim 1, wherein the system is arranged such that all
of said condensate produced in said condenser is recycled to said
recuperator, said portion of said condensate received by said first
vaporizer and said further portion of said condensate received by
second vaporizer being supplied from said recuperator as heated
condensate..Iaddend.
.Iadd.34. A waste heat recovery system utilizing a working fluid
according to claim 1, wherein the system is arranged such that
portion of said condensate produced in said condenser is recycled
to said recuperator, said portion of said condensate received by
said first vaporizer being supplied from said condenser, while said
further portion of said condensate received by second vaporizer
being supplied from said recuperator as heated
condensate..Iaddend.
.Iadd.35. The waste heat recovery system according to claim 1
wherein said first vaporizer is arranged to receive heat from said
low-temperature heat source through a first further working fluid
and said first vaporizer is configured to produce heat-depleted
first further working fluid along with said low pressure working
fluid vapor..Iaddend.
.Iadd.36. The waste heat recovery system according to claim 35
wherein said first further working fluid is cooling
water..Iaddend.
.Iadd.37. The waste heat recovery system according to claim 32
wherein said second vaporizer is arranged to receive heat from said
high-temperature heat source through a heat transfer fluid and said
second vaporizer produces heat-depleted heat transfer fluid along
with said high pressure working fluid vapor..Iaddend.
Description
BACKGROUND
1. Field
This disclosure relates generally to the field of power generation
using waste heat. More particularly, the disclosure relates to a
system and method for recovering waste heat from a plurality of
heat sources having different temperatures for generation of
electricity.
2. Background
Significant amounts of waste heat are generated by a wide variety
of industrial and commercial processes and operations. Example of
sources of waste heat include heat from space heating assemblies,
steam boilers, engines, and cooling systems. In general, waste heat
is discharged into the environment, or occasionally used as a low
grade heat source for space heating and the like.
In a typical system based on the waste heat of an internal
combustion engine or other fuel-based heat source, the original
source of heat (the engine) discharges heat in the form of exhaust
and discharges an additional amount of heat in the form of
mechanical cooling (engine cooling).
One method to generate electricity from the waste heat of a
combustion engine is to apply a bottoming Rankine cycle. A Rankine
cycle engine typically includes a water-based system including a
turbo generator, an evaporator/boiler and a condenser; however,
water based steam Rankine cycles are unattractive for low
temperature waste heat systems due to high cost and low efficiency.
The performance of an organic Rankine cycle (ORC) is limited by
constraints of the working fluid circulated within the ORC. Any
pure chemical used as a working fluid may be optimal for a specific
limited range of cycle temperatures and pressures. It is therefore
difficult to maximize the power output of a single fluid ORC for a
system with waste heat sources of different temperature levels. The
working fluid is a thermodynamic medium which functions as a
working fluid in the system.
Externally Fired Gas Turbine (EGFT)/combined cycle systems have
been described in the literature for a number of years. Such
systems include a compressor for compressing ambient air, an
indirect contact heat exchanger in which combustible products,
e.g., gas and/or fuel vapors, hereinafter referred to as
"combustible gases", are burned to heat the compressed air, and a
turbine in which the heated compressed air is expanded driving a
generator that produces electricity. Heat contained in the turbine
exhaust is used to vaporize water that is converted into steam in a
separate water-based, closed Rankine cycle power plant, the steam
being expanded in a steam turbine in the power plant for driving a
generator that produces additional electricity.
Organic Rankine Cycle power plants have been proposed for operation
together with such systems, see for example U.S. Pat. Nos.
5,687,570, 5,799,490, 6,167,706 and 6,497,090, the disclosures of
which are hereby incorporated by reference. In these patents, while
an Organic Rankine Cycle power plant is described which produces
power as a bottoming cycle to a steam turbine power cycle operated
by a gas turbine power unit, an Organic Rankine cycle is also
described which produces power from an intercooler of a compressor
of a gas turbine power unit, see for example FIGS. 5A, 6, 7, 8, 9
and 9A of the above patents. Furthermore, in these patents, while
Externally Fired Gas Turbine (EFGT) combined cycle systems are
described, combined cycle power plant systems are described with
include gas turbines that can be directly fired as well, see for
example FIGS. 8, 9, 9A.
EFGT systems have been proposed for use with low calorific, unclean
gaseous fuels as well as with hot gaseous fuels. Solid fuels are
more difficult to incorporate into EFGT systems because of the
problems associated with ash and noxious gases produced during the
combustion process.
SUMMARY
The present disclosure is directed to a waste heat recovery system
utilizing a working fluid comprising: a high pressure vapor turbine
receiving high pressure working fluid vapor and producing power and
low pressure working fluid vapor; a low pressure vapor turbine
receiving said low pressure working fluid vapor and producing power
and expanded working fluid vapor; a recuperator receiving said
expanded working fluid vapor and producing heat-depleted expanded
working fluid vapor; a condenser receiving said heat-depleted
expanded working fluid vapor and producing condensate, said
condensate recycled to said recuperator to produce heated
condensate and said heat-depleted expanded working fluid vapor; a
first vaporizer receiving a first portion of said heated condensate
and configured to receive heat from a low-temperature heat source,
thereby producing low pressure working fluid vapor; and a second
vaporizer receiving a second portion of said heated condensate and
configured to receive heat from a high-temperature heat source,
thereby producing said high pressure working fluid vapor.
Another aspect of the present disclosure is directed to a waste
heat recovery system utilizing a working fluid comprising: a high
pressure vapor turbine receiving high pressure working fluid vapor
and producing power and low pressure working fluid vapor; a low
pressure vapor turbine receiving said low pressure working fluid
vapor and producing power and expanded working fluid vapor; a
recuperator receiving said expanded working fluid vapor and
producing heat-depleted expanded working fluid vapor; a condenser
receiving said heat-depleted expanded working fluid vapor and
producing condensate, a first portion of said condensate recycled
to said recuperator to produce heated condensate and said
heat-depleted expanded working fluid vapor; a first vaporizer
receiving a second portion of said condensate and configured to
receive heat from a low-temperature heat source, thereby producing
low pressure working fluid vapor; and a second vaporizer receiving
said heated condensate and configured to receive heat from a
high-temperature heat source, thereby producing said high pressure
working fluid vapor.
A further aspect of the present subject matter is drawn to a waste
heat recovery system utilizing a working fluid comprising: a high
pressure vapor turbine receiving high pressure working fluid vapor
and producing power and expanded high pressure working fluid vapor;
a low pressure vapor turbine receiving low pressure working fluid
vapor and producing power and expanded low pressure working fluid
vapor; a condenser receiving said expanded high pressure working
fluid vapor and said expanded low pressure working fluid vapor and
producing condensate; a first vaporizer receiving a first portion
of said condensate and configured to receive heat from a
low-temperature heat source, thereby producing said low pressure
working fluid vapor; and a second vaporizer receiving a second
portion of said condensate and configured to receive heat from a
high-temperature heat source, thereby producing said high pressure
working fluid vapor.
A still further aspect of the present disclosure is directed to a
waste heat recovery system utilizing a working fluid comprising: a
high pressure vapor turbine receiving high pressure working fluid
vapor and producing power and expanded high pressure working fluid
vapor; a recuperator receiving said expanded high pressure working
fluid vapor and producing heat-depleted expanded high pressure
working fluid vapor; a first condenser receiving said heat-depleted
expanded high pressure working fluid vapor and producing first
condensate, said first condensate recycled to said recuperator to
produce heated condensate and said heat-depleted expanded high
pressure working fluid vapor; a first vaporizer receiving said
heated condensate and configured to receive heat from a
high-temperature heat source, thereby producing said high pressure
working fluid vapor; a low pressure vapor turbine receiving low
pressure working fluid vapor and producing power and expanded low
pressure working fluid vapor; a second condenser receiving said
expanded low pressure working fluid vapor and producing second
condensate; a second vaporizer receiving said second condensate and
configured to receive heat from a low-temperature heat source,
thereby producing said low pressure working fluid vapor; and a
generator connected to said high pressure vapor turbine and said
low pressure vapor turbine for producing power.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic diagram showing the operation of a system
with two turbines and two vaporizers.
FIG. 2 is a schematic diagram showing the operation of a system in
which condensate is directly charged to a low pressure
vaporizer.
FIG. 3 is a schematic diagram showing the operation of a system in
which using a common condenser receiving working fluid from two
turbines.
FIG. 4 is a schematic diagram showing the operation of a system in
which two turbines operate with independent fluid circuits.
FIG. 5 is a graph depicting temperature drop across a dual turbine
system.
It is noted that like reference numerals in the various figures
refer to similar components found within the figures.
DETAILED DESCRIPTION
Overview
The present technique provides an ability to extract waste heat
from two sources. Typically, these would be two related sources,
such as the coolant in a cooling jacket used for engine cooling,
heat discharged from an intercooler, or direct engine exhaust;
however, it is also possible to use the technique with two
unrelated heat sources.
An organic Rankine Cycle power system having two vaporizers and two
pressure level turbine system is used as a prime mover for driving
an electric generator. Two sources of waste heat are used with each
one of the two sources providing the heat for a respective one of
the two vaporizers.
By using the second heat source, e.g. cooling jacket water of an
internal combustion engine, and/or heated fluid from an intercooler
of turbo-charged or a turbo-charger of an internal combustion
engine or diesel engine, or gas engine, etc. as a heat source for
the second vaporizer, better heat source to heat user match is
achieved.
Recuperator Output Directed to High and Low Pressure Circuits
FIG. 1 is a schematic diagram showing the operation of a system
with two turbines and two vaporizers. In the configuration of FIG.
1, one vaporizer utilizes high-temperature heat from the exhaust
gases of an internal combustion engine, e.g. a diesel engine, gas
engine, etc., directly or by using heat transfer fluid. A second,
low-pressure vaporizer utilizes lower heat present, for example, in
the cooling water of the internal combustion engine and/or heated
fluid from a turbo-charger of an internal combustion engine.
Depicted are high pressure and low pressure vapor turbines 111,
112, connected via common drivetrain 115 to a single generator 117.
It is also contemplated that common drivetrain 115 connects the
high pressure and low pressure vapor turbines 111, 112 to multiple
generators. Also depicted are high pressure vaporizer 121,
preheater 125, low pressure vaporizer 131, recuperator 135,
condenser 137 and pump 141.
High pressure vaporizer 121 receives heat from a heat transfer
fluid such as, for example, a thermal oil, indicated at 151, and
transfers the heat to a working fluid, thereby producing a high
pressure working fluid vapor. Alternatively, high pressure
vaporizer 121 can receive heat directly from a heat source, such as
heat from exhaust gas of an internal combustion engine. High
pressure working fluid vapor from high pressure vaporizer 121 is
used to drive high pressure vapor turbine 111. The exhaust or
discharge from high pressure vapor turbine 111 is a low pressure
working fluid vapor and may be combined with other low pressure
working fluid vapor, as will be described, and used to drive low
pressure vapor turbine 112.
The working fluid vapor is used to drive high pressure vapor and
low pressure vapor turbines 111, 112. Examples of suitable working
fluids include, without limitation, water, an alcohol, ethane,
propane, butane, iso-butane, n-pentane, iso-pentane, hexane,
iso-hexane, and mixtures thereof, as well as a synthetic alkylated
aromatic heat transfer fluid, for example, the alkyl substituted
aromatic fluid Therminol LT (the commercial name of the Solutia
Company of Belgium), a mixture of isomers of an alkylated aromatic
fluid (Dowtherm J, registered trademark of The Dow Chemical
Company, USA) as described in U.S. Pat. No. 6,960,839, the
disclosure of which is incorporated by reference. In addition, also
one highly branched, heavy iso-paraffin hydrocarbon, or a mixture
of two or more of such hydrocarbons present as the major component
(i.e., at least 50% by volume) in the working fluid are included as
a non-limiting example of the working fluid. An exemplary class of
such an iso-paraffin includes 8 to 20, alternatively 9 to 20,
carbon atom-containing hydrocarbons having at least one methyl
radical (CH.sub.3) arranged to achieve a highly stable compound.
Furthermore, the branched iso-paraffins are highly branched,
meaning that they have 3-20 methyl groups attached to tertiary or
quaternary carbon atoms as described in U.S. Pat. No. 7,225,621,
the disclosure of which is incorporated by reference. In a further
aspect, the last mentioned example of working fluid comprises an
iso-paraffin selected from the group consisting of iso-dodecane or
2,2,4,6,6-pentamethylheptane, iso-eicosane or
2,2,4,4,6,6,8,10,10-nonamethylundecane, iso-hexadecane or
2,2,4,4,6,8,8-heptamethylnonane, iso-nonane or 2,2,4,4
tetramethylpentane, or alternatively iso-octane or 2,2,4
trimethylpentane and a mixture of two or more of these
compounds.
The heat transfer fluid or exhaust gas discharged from high
pressure vaporizer 121 is optionally passed through preheater 125.
Examples of suitable heat transfer fluids include, without
limitation, thermal oil, synthetic heat transfer fluid, or mixtures
thereof. When preheater 125 is engaged, high pressure vaporizer 121
can function as a superheater for the high pressure vaporized
working fluid that is provided to high pressure vapor turbine
111.
Preheater 125 receives heat depleted heat transfer fluid or exhaust
discharged from high pressure vaporizer 121 and produces further
heat-depleted heat transfer fluid and preheated working fluid. The
working fluid is passed to preheater 125 for producing preheated
working fluid prior to passing through high pressure vaporizer 121,
and consequently the extraction of heat from the heat transfer oil
or exhaust is increased and high pressure working fluid vapor is
produced.
Low pressure vaporizer 131 receives heat from a further working
fluid such as, for example, engine jacket coolant and/or heated
fluid from an intercooler of a turbocharger of the engine, which is
generally at a lower temperature than the exhaust gas. While it is
possible that the total heat output from this heat source may be
close to or exceed that of the internal combustion engine exhaust,
the heat source for low pressure vaporizer is considered to be a
lower grade heat source due to the lower temperature.
Turbine 112 is a low pressure vapor turbine. The system uses a
common working fluid for high pressure vapor and low pressure vapor
turbines 111 and 112, which permits mixing of fluids used to drive
the turbines 111 and 112. Low pressure vapor turbine 112 receives
its low pressure working fluid vapor from the discharge of high
pressure vapor turbine 112 and the output from low pressure
vaporizer 131. This permits low pressure vapor turbine 112 to be
optimized to efficiently extract power from the outflow from high
pressure vaporizer 121, while taking into consideration that the
energy from its discharge can be extracted by low pressure vapor
turbine 112, making it in effect a two stage turbine but with the
additional boost obtained from the outflow of low pressure
vaporizer 131.
Low pressure vapor turbine 112 provides expanded working fluid to
recuperator 135. A recuperator is a special purpose counter-flow
heat exchanger used to recover waste heat from exhaust vapors. The
outflow of low pressure vapor turbine 112 is directed to
recuperator 135 where the working fluid passes a heat extraction
circuit, thereby forming heat-depleted expanded working fluid
vapor. The heat-depleted expanded working fluid vapor is fed to
condenser 137 to produce condensate. In the hot pass side, heat is
extracted from the expanded working fluid vapor and transferred to
a cold pass side (internal to recuperator 135; not separately
depicted). The condensate from condenser 137 is fed to pump 141,
and is then supplied to recuperator 135, where the working fluid
condensate passes the cold pass side and receives the heat which
had been extracted from the expanded working fluid vapor in the hot
pass side thereby producing heated condensate. Recuperator 135 is
used to extract heat from the outflow of low pressure vapor turbine
112, prior to condensing in condenser 137 and then discharges the
heat back into the fluid supplied by pump 141.
A first portion of the heated condensate is fed to low pressure
vaporizer 131 and a second portion is fed to high pressure
vaporizer 121 possibly using a booster pump. This results in the
return of the working fluid back to high pressure vaporizer 121 and
high pressure turbine 111.
While FIG. 1 depicts the low pressure working fluid vapor from high
pressure vapor turbine 111 being combined with low pressure working
fluid vapor from low pressure vaporizer 131 prior to being fed to
low pressure vapor turbine 112, it is also contemplated that the
low pressure working fluid vapor from each source is combined at
the inlet of low pressure vapor turbine 112.
Recuperator Output Directed to High Pressure Circuit
FIG. 2 is a schematic diagram showing the operation of a system in
which condensate is directly charged to a low pressure vaporizer.
As is the case with the configuration of FIG. 1, the system
includes a high pressure side and a low pressure side. Most of the
components are similar to those of the configuration of FIG. 1.
Depicted are high pressure and low pressure turbines 211, 212,
connected via common drivetrain 215 to a single generator 217. It
is also contemplated that common drivetrain 215 connects the high
pressure and low pressure vapor turbines 211, 212 to multiple
generators. Also depicted are high pressure vaporizer 221,
preheater 225, low pressure vaporizer 231, recuperator 235,
condenser 237 and pump 241. As is the case with the configuration
of FIG. 1, high pressure vaporizer 221 receives heat from a heat
transfer fluid such as, for example, a thermal oil, indicated at
251, which transfers the heat to a working fluid vapor, or directly
from a heat source, such as heat from exhaust gas of an internal
combustion engine.
The working fluid vapor is used to drive high pressure vapor and
low pressure vapor turbines 211, 212. Examples of suitable working
fluids include, without limitation, water, an alcohol, ethane,
propane, butane, iso-butane, n-pentane, iso-pentane, hexane,
iso-hexane, and mixtures thereof, as well as a synthetic alkylated
aromatic heat transfer fluid, for example, the alkyl substituted
aromatic fluid Therminol LT (the commercial name of the Solutia
Company of Belgium), a mixture of isomers of an alkylated aromatic
fluid (Dowtherm J, registered trademark of The Dow Chemical
Company, USA) as described in U.S. Pat. No. 6,960,839, the
disclosure of which is incorporated by reference. In addition, also
one highly branched, heavy iso-paraffin hydrocarbon, or a mixture
of two or more of such hydrocarbons present as the major component
(i.e., at least 50% by volume) in the working fluid are included as
a non-limiting example of the working fluid. An exemplary class of
such an iso-paraffin includes 8 to 20, alternatively 9 to 20,
carbon atom-containing hydrocarbons having at least one methyl
radical (CH.sub.3) arranged to achieve a highly stable compound.
Furthermore; the branched iso-paraffins are highly branched,
meaning that they have 3-20 methyl groups attached to tertiary or
quaternary carbon atoms as described in U.S. Pat. No. 7,225,621,
the disclosure of which is incorporated by reference. In a further
aspect, the last mentioned example of working fluid comprises an
iso-paraffin selected from the group consisting of iso-dodecane or
2,2,4,6,6-pentamethylheptane, iso-eicosane or
2,2,4,4,6,6,8,10,10-nonamethylundecane, iso-hexadecane or
2,2,4,4,6,8,8-heptamethylnonane, iso-nonane or 2,2,4,4
tetramethylpentane, or alternatively iso-octane or 2,2,4
trimethylpentane and a mixture of two or more of these
compounds.
The working fluid vapor is at high pressure and is fed from high
pressure vaporizer 221 and used to drive high pressure turbine 211.
The heat transfer fluid or exhaust gas discharged from high
pressure vaporizer 221 is optionally passed through preheater 225.
When preheater 225 is employed, high pressure vaporizer 221 can
function as a superheater to superheat the high pressure working
fluid vapor that is provided to high pressure vapor turbine
211.
Preheater 225 receives heat depleted heat transfer fluid or exhaust
discharged from high pressure vaporizer 221 and produces further
heat-depleted heat transfer fluid and preheated working fluid.
Examples of suitable heat transfer fluids include, without
limitation, thermal oil, synthetic heat transfer fluid, or mixtures
thereof. The working fluid is optionally passed to preheater 225
prior to passing through high pressure vaporizer 221, which
increases the extraction of heat from the heat transfer fluid or
exhaust and forms the high pressure working fluid vapor.
As in the case with the configuration of FIG. 1, high pressure
turbine 211 produces low pressure working fluid vapor which is
combined with other low pressure fluid vapor and used to drive low
pressure vapor turbine 212. Low pressure vaporizer 231 receives
heat from a lower temperature heat source such as from engine
jacket coolant and/or an intercooler of a turbo-charger of the
engine and produces low pressure working fluid vapor. The low
pressure working fluid vapor is fed to low pressure vapor turbine
212.
Turbine 212 is a low pressure turbine. As is the case with the
configuration of FIG. 1, the system uses a common working fluid for
high pressure vapor and low pressure vapor turbines 211 and 212,
which permits mixing of fluids used to drive the turbines 211 and
212. Low pressure vapor turbine 212 receives its expanded working
fluid vapor from the discharge of high pressure vapor turbine 211
and the output from low pressure vaporizer 231. This permits high
pressure vapor turbine 211 to be optimized to efficiently extract
power from the outflow from high pressure vaporizer 221, while
taking into consideration that the energy from its discharge can be
extracted at low pressure vapor turbine 212, making it in effect a
two stage turbine but with the additional boost obtained from the
outflow of low pressure vaporizer 231.
Low pressure vapor turbine 212 receives heat from a further working
fluid such as, for example, engine jacket coolant or heated fluid
from an intercooler of a turbo-charger and produces expanded
working fluid vapor which is fed to a hot pass side of recuperator
235, thereby producing heat-depleted expanded working fluid vapor.
The heat-depleted expanded working fluid vapor from recuperator 235
is fed to condenser 237, whereby working fluid condensate is
produced. The working fluid condensate from condenser 237 is fed to
pump 241, and a first portion is then directed to recuperator 235,
where the working fluid condensate passes the cold pass side and
receives the heat which had previously been extracted from the
expanded working fluid vapor in the hot pass side to produce heated
condensate. Recuperator 235 is used to extract heat from the
expanded working fluid vapor of low pressure vapor turbine 212,
prior to condensing in condenser 237.
The heated condensate from recuperator 235 is fed to high pressure
vaporizer 231 and to preheater 225 using possibly a booster pump
242. This results in the return of the high pressure working fluid
vapor back to high pressure vaporizer 221 and high pressure vapor
turbine 211. Low pressure vaporizer 231 receives a second portion
of the condensate from condenser 237 and consequentially it is not
provided with fluid from the cold pass side of recuperator 235.
This balances the distribution of the working fluid condensate
between the high pressure and low pressure sides and also maximizes
the distribution of heat to the high pressure side of the system.
This also optimizes the heat extraction capability of the system
because the temperature difference between the source heat and the
working fluid to be heated by the source heat is matched at the
high pressure side and at the low pressure side.
As is the case with the configuration of FIG. 1, in the
configuration of FIG. 2, the vaporizer utilizing the higher
temperature heat source also provides a superheating function, to
superheat the working fluid present in the vaporizer.
The use of two heat sources having different temperatures is
thereby achieved in a more efficient manner. The heat from the two
sources is input into two different vaporizers to drive a two
pressure level organic Rankine cycle turbine system connected to
the single electric generator 217, or optionally to multiple
generators.
Condenser Output Directed to High Pressure Circuit
FIG. 3 is a schematic diagram showing the operation of a system in
which using a common condenser receiving working fluid from two
turbines. As is the case with the configuration of FIGS. 1 and 2,
the system includes a high pressure side 301 and a low pressure
side 302.
Depicted are high pressure and low pressure turbines 311, 312,
connected via common drivetrain 315 to a single generator 317. It
is also contemplated that common drivetrain 315 connects the high
pressure and low pressure vapor turbines 311, 312 to multiple
generators. Also depicted are high pressure vaporizer 321,
preheater 325, low pressure vaporizer 331, and a common condenser
335. Two pumps 343, 345 are depicted. As is the case with the
configuration of FIGS. 1 and 2, high pressure vaporizer 321
receives heat from a heat transfer fluid such as, for example, a
thermal oil, indicated at 351, which transfers the heat to a
working fluid vapor, or directly from a heat source, such as heat
from exhaust gas of an internal combustion engine.
The working fluid vapor is used to drive high pressure vapor and
low pressure vapor turbines 311, 312. Examples of suitable working
fluids include, without limitation, water, an alcohol, ethane,
propane, butane, iso-butane, n-pentane, iso-pentane, hexane,
iso-hexane, and mixtures thereof, as well as a synthetic alkylated
aromatic heat transfer fluid, for example, the alkyl substituted
aromatic fluid Therminol LT (the commercial name of the Solutia
Company of Belgium), a mixture of isomers of an alkylated aromatic
fluid (Dowtherm J; registered trademark of The Dow Chemical
Company, USA) as described in U.S. Pat. No. 6,960,839, the
disclosure of which is incorporated by reference. In addition, also
one highly branched, heavy iso-paraffin hydrocarbon, or a mixture
of two or more of such hydrocarbons present as the major component
(i.e., at least 50% by volume) in the working fluid are included as
a non-limiting example of the working fluid. An exemplary class of
such an iso-paraffin includes 8 to 20, alternatively 9 to 20,
carbon atom-containing hydrocarbons having at least one methyl
radical (CH.sub.3) arranged to achieve a highly stable compound.
Furthermore, the branched iso-paraffins are highly branched,
meaning that they have 3-20 methyl groups attached to tertiary or
quaternary carbon atoms as described in U.S. Pat. No. 7,225,621,
the disclosure of which is incorporated by reference. In a further
aspect, the last mentioned example of working fluid comprises an
iso-paraffin selected from the group consisting of iso-dodecane or
2,2,4,6,6-pentamethylheptane, iso-eicosane or
2,2,4,4,6,6,8,10,10-nonamethylundecane, iso-hexadecane or
2,2,4,4,6,8,8-heptamethylnonane, iso-nonane or 2,2,4,4
tetramethylpentane, or alternatively iso-octane or 2,2,4
trimethylpentane and a mixture of two or more of these
compounds.
The working fluid vapor is at high pressure and is fed from high
pressure vaporizer 321 to high pressure turbine 311. High pressure
vapor turbine 311 produces power and expanded high pressure working
fluid vapor, which is fed to common condenser 337.
The heat transfer fluid or exhaust gas discharged from high
pressure vaporizer 321 is optionally passed through preheater 325.
Examples of suitable heat transfer fluids include, without
limitation, thermal oil, synthetic heat transfer fluid, or mixtures
thereof When preheater 325 is used, high pressure vaporizer 321
functions as a superheater to superheat the high pressure working
fluid vapor that is provided to high pressure turbine 311.
Preheater 325 receives heat depleted heat transfer fluid or exhaust
discharged from high pressure vaporizer 321 and produces further
heat-depleted heat transfer fluid and preheated working fluid. The
working fluid is passed to preheater 325 prior to passing through
high pressure vaporizer 321, which increases the extraction of heat
from the heat transfer fluid or exhaust and forms the high pressure
working fluid vapor.
In this configuration, the expanded high pressure working fluid
vapor from high pressure vapor turbine 311 is provided directly to
the common condenser 335 without the use of a recuperator.
Turbine 312 is a low pressure turbine and receives low pressure
working fluid vapor from low pressure vaporizer 331. Low pressure
vapor turbine 312 produces expanded low pressure working fluid
vapor that is fed directly to common condenser 335. Low pressure
vaporizer 331 receives heat from a lower temperature heat source
such as from engine jacket coolant and/or heated fluid from an
intercooler of a turbo-charger of the engine and produces low
pressure working fluid vapor that is fed to low pressure vapor
turbine 312. In this example, low pressure vaporizer 331 includes a
preheater, depicted as integral with vaporizer 331.
As is the case with the configuration of FIGS. 1 and 2, the system
uses a common working fluid for high pressure vapor and low
pressure vapor turbines 311 and 312, which permits mixing of fluids
used to drive the turbines 311 and 312. In this configuration, low
pressure vapor turbine 312 receives the low pressure working fluid
vapor from the output of low pressure vaporizer 331, but does not
receive the discharge from high pressure vapor turbine 311, which
instead goes directly to the condenser 335. This permits low
pressure vapor turbine 312 to be optimized to efficiently extract
power from the outflow from low pressure vaporizer 331 and to
receive the low pressure working fluid vapor independent of the
discharge of high pressure vapor turbine 311.
Condenser 335 receives the expanded high pressure working fluid
vapor and the expanded low pressure working fluid vapor and
produces condensate. The condensate is directed to pump 341. A
first portion of the condensate is pumped to low pressure vaporizer
331. A second portion of the condensate is pumped to a second
booster pump, 342. The second portion of condensate is then fed to
high pressure vaporizer 321, optionally via preheater 325. Pump 342
provides the working fluid to preheater 325 at an increased
pressure above that provided to low pressure vaporizer 331. The use
of two pumps 341, 342 permits a desired balance to be achieved
between the high pressure side 301 and low pressure side 302.
Similar results can be achieved with one pump 341 by providing a
restrictor or throttle valve in the connection between pump 342 and
low pressure vaporizer 331. If the flow of fluid to low pressure
vaporizer 331 is adequately restricted, then pump 342 can be
eliminated.
As is the case with the configuration of FIGS. 1 and 2, in the
configuration of FIG. 3, the vaporizer utilizing the higher
temperature heat source can also provide a superheating function,
to superheat the working fluid present in the vaporizer when the
preheater is present.
The use of two heat sources having different temperatures is
thereby achieved in a more efficient manner. The heat from the two
sources is input into two different vaporizers to drive a two
pressure level organic Rankine cycle turbine system connected to
the single electric generator 317 or to multiple generators.
Separate High Pressure and Low Pressure Circuits
FIG. 4 is a schematic diagram showing the operation of a system in
which fluid circuits associated with two turbines are separate. As
is the case with the configuration of FIGS. 1-3, the system
includes a high pressure side 401 and a low pressure side 402.
Depicted are high pressure and low pressure turbines 411, 412,
connected via common drivetrain 415 to a single generator 417. It
is also contemplated that common drivetrain 415 connects the high
pressure and low pressure vapor turbines 411, 412 to multiple
generators. Also depicted are high pressure vaporizer 421,
preheater 425 and a low pressure vaporizer 431. The system uses
separate condensers 432, 434, a single recuperator 435 and two
pumps 447, 449. As is the case with the configuration of FIGS. 1
and 2, high pressure vaporizer 421 receives heat from a heat
transfer fluid such as, for example, a thermal oil, which transfers
the heat to a working fluid vapor, or directly from a heat source,
such as heat from exhaust gas of an internal combustion engine.
The working fluid vapor is used to drive high pressure vapor
turbine 411. Examples of suitable working fluids include, without
limitation, water, an alcohol, ethane, propane, butane, iso-butane,
n-pentane, iso-pentane, hexane, iso-hexane, and mixtures thereof,
as well as a synthetic alkylated aromatic heat transfer fluid, for
example, the alkyl substituted aromatic fluid Therminol LT (the
commercial name of the Solutia Company of Belgium), a mixture of
isomers of an alkylated aromatic fluid (Dowtherm J, registered
trademark of The Dow Chemical Company, USA) as described in U.S.
Pat. No. 6,960,839, the disclosure of which is incorporated by
reference. In addition, also one highly branched, heavy
iso-paraffin hydrocarbon, or a mixture of two or more of such
hydrocarbons present as the major component (i.e., at least 50% by
volume) in the working fluid are included as a non-limiting example
of the working fluid. An exemplary class of such an iso-paraffin
includes 8 to 20, alternatively 9 to 20, carbon atom-containing
hydrocarbons having at least one methyl radical (CH.sub.3) arranged
to achieve a highly stable compound. Furthermore, the branched
iso-paraffins are highly branched, meaning that they have 3-20
methyl groups attached to tertiary or quaternary carbon atoms as
described in U.S. Pat. No. 7,225,621, the disclosure of which is
incorporated by reference. In a further aspect, the last mentioned
example of working fluid comprises an iso-paraffin selected from
the group consisting of iso-dodecane or
2,2,4,6,6-pentamethylheptane, iso-eicosane or
2,2,4,4,6,6,8,10,10-nonamethylundecane, iso-hexadecane or
2,2,4,4,6,8,8-heptamethylnonane, iso-nonane or 2,2,4,4
tetramethylpentane, or alternatively iso-octane or 2,2,4
trimethylpentane and a mixture of two or more of these
compounds.
Non-limiting examples of the working fluid of the low pressure
turbine cycle are water, alcohol, ethane, propane, butane,
iso-butane, n-pentane, iso-pentane, hexane, iso-hexane and mixtures
thereof.
The high pressure working fluid vapor is fed from high pressure
vaporizer 421 and used to drive high pressure vapor turbine 411.
The heat transfer fluid or exhaust gas discharged from high
pressure vaporizer 421 is optionally passed through preheater 425.
When preheater 425 is used, high pressure vaporizer 421 functions
as a superheater for the high pressure vaporized working fluid that
is provided to high pressure vapor turbine 411.
Preheater 425 receives heat depleted heat transfer fluid or exhaust
discharged from high pressure vaporizer 421 and produces further
heat-depleted heat transfer fluid and preheated working fluid.
Examples of suitable heat transfer fluids include, without
limitation, thermal oil, synthetic heat transfer fluid, or mixtures
thereof The working fluid is passed to preheater 425 prior to
passing through high pressure vaporizer 421, which increases the
extraction of heat from the heat transfer oil or exhaust and forms
the high pressure working fluid vapor.
In this configuration, the fluid circuits for the high pressure
side 401 and the low pressure side 402 are separate, although
turbines 411, 412 are optionally connected via the common
drivetrain 415 as mentioned above.
Turbine 411 is a high pressure turbine, and receives the high
pressure working fluid vapor from high pressure vaporizer 421. High
pressure vapor turbine produces power via generator 417 and also
expanded high pressure working fluid vapor.
Expanded high pressure working fluid vapor from high pressure vapor
turbine 411 is directed to recuperator 435 where the working fluid
passes through a heat extraction circuit (internal to recuperator
435; not separately depicted) forming heat-depleted expanded high
pressure working fluid vapor. The heat-depleted expanded high
pressure working fluid vapor is then fed to a first condenser 432.
In the hot pass side, heat is extracted from the expanded high
pressure working fluid vapor and transferred to a cold pass side
(internal to recuperator 435; not separately depicted). Condenser
432 produces a first condensate, which is fed to pump 442, and is
then supplied to recuperator 435. The first condensate passes the
cold pass side of recuperator 435 and receives the heat which had
been extracted from the expanded high pressure working fluid vapor
in the hot pass side, thereby producing heated condensate.
Recuperator 435 is used to extract heat from the outflow of high
pressure turbine 411, prior to condensing in condenser 432 and then
discharges the heat back into the fluid supplied by pump 442. The
heated condensate is then fed to high pressure vaporizer 421,
optionally via preheater 425.
Turbine 412 is a low pressure vapor turbine and receives low
pressure working fluid vapor from low pressure vaporizer 431. Low
pressure vaporizer 431 receives heat from a lower temperature heat
source such as from engine jacket coolant and/or heated fluid from
an intercooler of a turbo-charger of the engine. In this example,
low pressure vaporizer 431 favorably includes a preheater, depicted
for example as integral with vaporizer 431.
Low pressure vapor turbine 412 produces power and expanded low
pressure working fluid vapor. The expanded low pressure working
fluid vapor is provided to second condenser 434, which produces a
second condensate. The second condensate of condenser 434 is
directed to pump 441, and the output from pump 441 is directed to
low pressure vaporizer 431 for supplying second condensate to this
vaporizer. While a recuperator is not shown on the low pressure
side 402, it is possible to use a recuperator on the low pressure
side 402 as well.
As indicated above, high pressure side 401 and low pressure side
402 are connected by generator 417, which is connected by a common
drive train to both high pressure vapor turbine 411 and low
pressure vapor turbine 412.
The system in this example does not require the use of a common
working fluid for high pressure vapor and low pressure vapor
turbines 411 and 412. This permits turbines 411 and 412 to be
optimized to efficiently extract power according the thermal
characteristics of their respective heat sources. Despite the
separate working fluid circuits for turbines 411 and 412, the use
of two heat sources having different temperatures is thereby
achieved in a more efficient manner. The heat from the two sources
is input into two different vaporizers to drive a two pressure
level organic Rankine cycle turbine system connected to the single
electric generator 417 or to multiple generators.
Energy Conversion
FIG. 5 is a graph depicting an example of the temperature drop
across a dual turbine system for a system such as depicted in FIGS.
1 and 2. This depiction is for explanation only and does not
represent actual results or actual calculations. The temperatures
are those of the heat source and are represented by steep line 511
and shallow line 512. On the left side of the graph, steep line 511
indicates a temperature drop through high pressure vaporizer 121
(FIG. 1) or 221 (FIG. 2). The temperature drop is represented as a
drop from 275.degree. C. to 100.degree. C. Shallow line 512 on the
right side of the graph depicts a lesser temperature drop through
low pressure vaporizer 131 (FIG. 1) or 231 (FIG. 2). The
temperature drop is represented as a drop from 95.degree. C. to
85.degree. C. A turbine optimized for extracting energy
corresponding to steep line 511 would have vaporizer-preheater
design parameters depicted by line 513 while a turbine optimized
for extracting energy corresponding to shallow line 512 would have
vaporizer-preheater design parameters depicted by line 514.
The temperature drops for FIGS. 3 and 4 would be similar, even
though there is no serial fluid connection between turbines 311 and
312 (FIG. 3). or turbines 411 and 412 (FIG. 4).
In this depiction, the energy extracted from heat source depicted
by steep line 511 is 3.4 MW, and the energy extracted heat source
depicted by shallow line 512 is 1.9 MW. As can be seen, the amount
of energy from the heat source to shallow line 512 (1.9 MW) is
proportionally greater than the amount extracted corresponding to
steep line 511, as compared to the differences in temperature
drops. This would result from a larger amount of heat being
extracted corresponding to shallow line 512, and generally
corresponds to a larger volume of fluid flowing through low
pressure turbine 112 (FIG. 1) or 212 (FIG. 2).
Scalability
The system is scalable, in that more than two vaporizers and
turbines can be used. One example would be the use of an
intercooler of a turbo-charger to provide a low level heat source.
The low level heat source can be used to preheat the working fluid
supplied to one of the other vaporizers, or can be used to drive a
separate turbine. To the extent that the working fluid is able to
extract heat from the intercooler, the additional heat exchange
enhances the efficiency of the turbocharger.
While the above description refers to an engine jacket coolant
and/or the intercooler of a supercharger or turbocharger of an
internal combustion engine, it is contemplated that the present
subject matter can also be carried out wherein the low pressure
vaporizer receives heat from heated fluid from an intercooler of a
compressor of a gas turbine.
It will be understood that many additional changes in the details,
materials, steps and arrangement of parts, which have been herein
described and illustrated to explain the nature of the subject
matter, may be made by those skilled in the art within the
principle and scope of the invention as expressed in the appended
claims.
* * * * *