U.S. patent application number 11/237948 was filed with the patent office on 2007-10-18 for integration of igcc plant with superconducting power island.
Invention is credited to James William Bray, Richard Anthony Depuy, James Michael Fogarty, Albert Eugene Steinbach, John Arthur Urbahn.
Application Number | 20070240451 11/237948 |
Document ID | / |
Family ID | 38603547 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070240451 |
Kind Code |
A1 |
Fogarty; James Michael ; et
al. |
October 18, 2007 |
Integration of IGCC plant with superconducting power island
Abstract
A cooling system for high temperature superconductor equipment
comprising a cryocooler in heat exchange relationship with the high
temperature superconductor equipment, and an air separation unit in
heat exchange relationship with the cryocooler, the system arranged
such that heat from the high temperature superconductor equipment
is rejected to said air separation unit via the cryocooler.
Inventors: |
Fogarty; James Michael;
(Schenectady, NY) ; Steinbach; Albert Eugene;
(Schenectady, NY) ; Bray; James William;
(Niskayuna, NY) ; Urbahn; John Arthur; (Saratoga
Springs, NY) ; Depuy; Richard Anthony; (Burnt Hills,
NY) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Family ID: |
38603547 |
Appl. No.: |
11/237948 |
Filed: |
September 29, 2005 |
Current U.S.
Class: |
62/643 ;
62/259.2 |
Current CPC
Class: |
F25J 3/04612 20130101;
F25J 3/04563 20130101; F25J 3/04521 20130101; F25J 2245/42
20130101; F25J 3/04545 20130101; F25B 9/06 20130101; F25B 9/002
20130101; F25B 9/14 20130101; F25J 2270/912 20130101; F25J 2260/44
20130101 |
Class at
Publication: |
062/643 ;
062/259.2 |
International
Class: |
F25D 23/12 20060101
F25D023/12; F25J 3/00 20060101 F25J003/00 |
Goverment Interests
[0001] This invention was made with Government support under
contract number DE-FC36-02GO11100 awarded by U.S. Department of
Energy. The Government has certain rights in the invention.
Claims
1. A cooling system for high temperature superconductor equipment
comprising a cryocooler in heat exchange relationship with the high
temperature superconductor equipment; and an air separation unit in
heat exchange relationship with said cryocooler, said system
arranged such that heat from said high temperature superconductor
equipment is transferred to said air separation unit via said
cryocooler.
2. The cooling system of claim 1, wherein said cryocooler includes
a first heat exchanger and wherein a cryogenic fluid utilized in
said air separation unit passes in heat exchange relationship with
gaseous fluid from said high temperature superconductor equipment
in said first heat exchanger.
3. The cooling system of claim 2, wherein said air separation unit
includes a second heat exchanger, and wherein said cryogenic fluid
passes in heat exchange relationship with said gaseous fluid in
said second heat exchanger.
4. The cooling system of claim 2, wherein said gaseous fluid is
compressed in a compressor upstream of said first heat exchanger
and expanded in an expansion turbine downstream of said fuel heat
exchanger.
5. The cooling system of claim 1 in combination with an integrated
gasification combined cycle power plant, and wherein said air
separation unit is arranged to supply oxygen to said integrated
gasification combined cycle power plant.
6. The cooling system of claim 1 wherein said cryocooler operates
in a Reverse Brayton cooling cycle.
7. The cooling system of claim 1, wherein a first, closed cooling
circuit loop extends between said high temperature superconductor
equipment and said first heat exchanger; a second closed cooling
circuit loop extends between said first heat exchanger and a second
heat exchanger in said air separation unit, and a third closed
cooling circuit loop extends between said second heat exchanger and
said air separation unit.
8. The cooling system of claim 7 wherein said first closed cooling
circuit loop circulates a cooling fluid from a group comprising
gaseous helium, liquid or gaseous neon and liquid or gaseous
nitrogen.
9. The cooling system of claim 8 wherein said second closed cooling
circuit circulates liquid or gaseous nitrogen.
10. The cooling system of claim 9 wherein said third cooling
circuit circulates liquid or gaseous nitrogen, or liquid air.
11. The cooling system of claim 1 wherein said cryocooler operates
in a Gifford-McMahon-cooling cycle.
12. The cooling system of claim 11 wherein cryogenic cooling fluid
from said air separation unit is connected in parallel to first and
second heat exchangers, said first heat exchanger also receiving
coolant from said high temperature superconductor equipment and
said second heat exchanger also receiving coolant from said
cryocooler.
13. The cooling system of claim 12 including a third counterflow
heat exchanger arranged to receive said coolant from said high
temperature superconductor equipment upstream of said first heat
exchanger, with a compressor between said first and third heat
exchangers.
14. The cooling system of claim 13 wherein said coolant from said
high temperature superconductor equipment flows back through said
third counterflow heat exchanger downstream of said first heat
exchanger.
15. The cooling system of claim 1 wherein cryogenic fluid cooled in
said air separation unit is passed through said cyrocooler and
directly to said high temperature superconductor equipment and
returned to the air separation unit.
16. The cooling system of claim 15 wherein said cyrocooler includes
a pump and flow controller for supplying the cryogenic fluid to the
high temperature superconductor equipment.
17. A cooling system for high temperature superconductor equipment
comprising a cryocooler in heat exchange relationship with the high
temperature superconductor equipment; and an air separation unit in
heat exchange relationship with said cryocooler, said system
arranged such that heat from said high temperature superconductor
equipment is transferred to said air separation unit via said
cryocooler; wherein said cryocooler includes a first heat exchanger
and wherein a cryogenic fluid utilized in said air separation unit
passes in heat exchange relationship with gaseous helium or neon
from said high temperature superconductor equipment in said first
heat exchanger; wherein said air separation unit includes a second
heat exchanger, and wherein said cryogenic fluid passes in heat
exchange relationship with said gaseous helium or neon in said
second heat exchanger; and further wherein said gaseous helium or
neon is compressed in a compressor upstream of said first heat
exchanger and expanded in an expansion turbine downstream of said
first heat exchanger.
18. A method of cooling high temperature superconductor equipment
comprising: (a) integrating cooling hardware of the high
temperature superconductor equipment with an air separation unit of
an integrated gasification combined-cycle power plant; and (b)
transferring heat from the high temperature superconductor
equipment to fluid in the air separation unit.
19. The method of claim 18 wherein said cooling hardware comprises
a cryocooler and wherein (b) is carried out with said cryocooler
operably connected between said high temperature superconductor
equipment and said air separation unit.
20. The method of claim 19 wherein fluid in said air separation
unit is between 63.degree. and 90.degree. K.
Description
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to the cooling of equipment
utilizing superconductors and more specifically, to the linking of
a cyrocooler for high temperature superconductors with an air
separation unit in a power generation plant.
[0003] One of the fundamental problems presented by various
equipment that utilize superconductors is that the superconductors
must be kept within a strict cryogenic temperature range so that
the superconductors remain in a superconducting state. If, for
example, the temperature is increased above the critical range even
briefly, heat is generated within the superconducting wire that
could cause further increases in temperature and perhaps lead to
equipment failure.
[0004] Cryocoolers capable of cooling at temperatures between 4.2 K
and 77 K have long been available. However, it is insufficient to
simply achieve the operating temperature range. The cryocooler must
also be capable of removing heat for a given application (its
cooling capacity in watts). In this regard, removing 10 watts at 30
K is much easier than removing 500 watts at the same temperature.
Moreover, depending on the thermodynamic cycle being used, a 500
watt heat load could be merely difficult or practically impossible
to remove.
[0005] Users of power equipment expect that equipment to be
extremely reliable. Typical allowances for unreliability for a
complete turbine-generator limit the generator to only eight hours
downtime each year. Each component within the generator must be
even more reliable so that the entire generator achieves the stated
goal. As applied to a cryocooler, the reliability budget for the
equipment forces the use of redundant systems and equipment that
allows online maintenance to avoid unnecessary downtime. As a
result, reliability brings both complexity and cost to the
cryocooler.
[0006] It is now generally known that superconducting equipment can
be used in power stations. The equipment presently includes power
cables, transformers, generators, fault current limiters and the
like. Given that each of these components employs superconducting
materials at some cryogenic temperature, and that production of
coolants at cryogenic temperatures can be expensive and perhaps
unreliable, a means is desired whereby cooling capacity at
temperatures between, for example, liquid helium and liquid
nitrogen is readily available at an economical cost.
BRIEF DESCRIPTION OF THE INVENTION
[0007] In an exemplary embodiment of this invention, a cryocooler
for high temperature superconductors (HTS) is used that links into
the basic process for creating relatively pure oxygen in an
integrated gasification combined cycle (IGCC) power plant.
[0008] Coal gasification processes convert solid coal into
synthetic gas, primarily CO and H.sub.2. Typically, O.sub.2 is used
as the oxidizing medium. In an 1GCC plant, a cryogenic air
separation unit (ASU) is often used to provide pure oxygen to the
gasification reactor, often using or supplemented by,
post-compression air bleed from the gas turbine. The ASU typically
produces nitrogen and oxygen in the range of 63-90 K, depending on
the point within the cycle being considered, and at mass flow rates
that are very high compared to the cooling requirements of HTS
equipment. The typical cryocooler for HTS applications operates
between room temperature (25.degree. C.) and the HTS operating
temperature which may be between 30 K and 77 K. For example, in a
generator, the HTS field winding may operate at 30 K while in an
underground power cable, the HTS wires could be bathed in liquid
nitrogen at 77 K. The key technology in known cryocoolers is the
transfer of heat from the very cold cryogenic region to ambient air
or other heat sinks at room temperature.
[0009] In accordance with this invention, however, the HTS
cryocooler is modified so that the thermodynamic cycle operates
between the desired HTS wire temperature and a heat sink much
closer in temperature to the wire compared to room temperature.
This is done by linking the cryocooler into the air separation
process, reducing the complexity and capital cost of the cryocooler
without sacrificing operating reliability.
[0010] Compared to existing cryocoolers that operate between an
ambient temperature of 25.degree. C. and a working temperature of
30 K, the heat sink for the cryocooler in the example embodiment is
approximately 77 K. The reduction in the "apparent" ambient
temperature allows the cryocooler to be simpler, less expensive and
more reliable. In addition, it consumes less power, thereby
improving the efficiency advantage of the HTS equipment.
[0011] In one exemplary embodiment, the cryocooler is based on a
Reverse Brayton cooling cycle. Specifically, cold fluid from the
ASU enters a reservoir available to the cryocooler and cools a
separate fluid circulating between the cryogenic reservoir and a
recuperative heat exchanger in the cryocooler. A separate fluid
circulates between the recuperative heat exchanger and the HTS
equipment. By rejecting heat from the HTS equipment to the
cryogenic reservoir at a temperature of 63-90 K, instead of to a
traditional heat sink at room temperature, i.e., 25.degree. C. (or
298 K), the complexity of the cryocooler can be reduced along with
capital cost.
[0012] In a second exemplary embodiment, the ASU may be linked with
an otherwise conventional Gifford-McMahon (GM) cryocooler. In this
embodiment, a pair of auxiliary heat exchangers is inserted in the
links from the GM cryocoder compressors. One side of these heat
exchangers is fed from the compressor and the other side from
nitrogen lines from the ASU.
[0013] In a third exemplary embodiment, nitrogen (gaseous or
liquid) or liquefied air, which is to a large extent a by-product
of the ASU cycle, is simply supplied as the primary coolant to the
HTS equipment. The connection between the ASU and HTS equipment can
be through insulated piping or via dewars (in the case of liquid
coolants) that are filled by the ASU and moved as needed to the HTS
equipment.
[0014] Accordingly, in one aspect, the present invention relates to
a cooling system for high temperature superconductor equipment
comprising a cryocooler in heat exchange relationship with the high
temperature superconductor equipment, and an air separation unit in
heat exchange relationship with the cryocooler, said system
arranged such that heat from the high temperature superconductor
equipment is transferred to said air separation unit via the
cryocooler.
[0015] In another aspect, the invention relates to a cooling system
for high temperature superconductor equipment comprising a
cryocooler in heat exchange relationship with the high temperature
superconductor equipment, and an air separation unit in heat
exchange relationship with the cryocooler, the system arranged such
that heat from the high temperature superconductor equipment is
transferred to the air separation unit via the cryocooler, wherein
the cryocooler includes a first heat exchanger and wherein a
cryogenic fluid utilized in the air separation unit passes in heat
exchange relationship with gaseous helium or neon from the high
temperature superconductor equipment in the first heat exchanger,
wherein the air separation unit includes a second heat exchanger,
and wherein the cryogenic fluid passes in heat exchange
relationship with said gaseous helium or neon in the second heat
exchanger, and further wherein the gaseous helium or neon is
compressed in a compressor upstream of the first heat exchanger and
expanded in an expansion turbine downstream of the first heat
exchanger.
[0016] In still another aspect, the invention relates to a method
of cooling high temperature superconductor equipment comprising (a)
integrating cooling hardware of the high temperature superconductor
equipment with an air separation unit of an integrated gasification
combined-cycle power plant, and (b) transferring heat from the high
temperature superconductor equipment to fluid in the air separation
unit.
[0017] The invention will now be described in connection with the
drawings identified below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic diagram of a Reverse Brayton-type
cryocooler connected between a cryogenic reservoir of an air
separation unit in an IGCC plant and equipment utilizing high
temperature superconductors in accordance with a first exemplary
embodiment;
[0019] FIG. 2 is a schematic diagram of a Gifford-McMahon cycle
cryocooler connected between an air separation unit in an IGCC
plant and equipment utilizing high temperature superconductors in
accordance with a second exemplary embodiment; and
[0020] FIG. 3 is a schematic diagram of an arrangement where the
equipment utilizing high temperature superconductors is cooled
directly by fluid from an air separation unit in accordance with a
third exemplary embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The exemplary embodiments describe different arrangements
for using a cryocooler for high temperature superconductors that
links into the basic process for creating relatively pure oxygen in
an IGCC power plant. FIG. 1 illustrates an arrangement 10 utilizing
a Reverse Brayton cooling cycle cryocooler. This arrangement
includes an otherwise conventional cryocooler 12 fluidly connected
to a cryogenic reservoir 14 of an air separation unit (ASU) 16 that
is incorporated into an IGCC plant 17 and that supplies pure oxygen
(02) thereto. In this arrangement, cold fluid enters the reservoir
14 via line 18 and exits through the reservoir 14 via line 20 for
return to the ASU. The fluid in this circuit (AB) is typically
liquid nitrogen or liquid air at a temperature of between 63-92 K.
The fluid in line 20 is slightly higher in temperature than in line
A because of the heat rejected (i.e., transferred) from the
cryocooler to the ASU, and at a slightly lower pressure because of
the pressure losses within the reservoir 14.
[0022] By means of a separate circuit (CD), fluid cooled in the
reservoir 14 enters a heat exchanger 22 in the cryocooler 12 via
line 24 and flow controller 25, and returns to the reservoir 14 via
line 26. The fluid in line 24 is at a temperature slightly greater
than the temperatures in line 18 or 20, but less than the fluid
temperature in line 26. The fluid in this circuit could also be
liquid nitrogen but the circuits AB and CD are separate and
discreet circuits. A separate cooling loop (EF) in the cryocooler
12 cools the HTS equipment 28, with cooling fluid from the heat
exchanger 22 expanded in the turbine 30 via line 32 and returned to
the heat exchanger via line 34. A valve 36 in line 38 upstream of
the HTS equipment 28 provides an optional bypass in the event flow
to the HTS needs to be adjusted. In this way, the heat generated in
the cryocooler 12 by the HTS equipment can be rejected to the cool
fluid in the ASU rather than to a relatively high (room)
temperature heatsink.
[0023] FIG. 2 illustrates a second embodiment including an
arrangement 40 where an air separation unit 42 for an IGCC plant 45
is linked to a Gifford-McMahon (GM) cryocooler 44 used to cool the
HTS equipment 46. More specifically, liquid nitrogen (or LN.sub.2)
or liquid air from the ASU 42 is circulated to a first auxiliary
heat exchanger 50 via line 48 and flow controller 49, and returned
to the ASU via line 52. Approximately half of the cold liquid in
line 48 is diverted to a parallel, second auxiliary heat exchanger
54 via line 56 and returned to the ASU via lines 58 and 52.
[0024] The cryogenic fluid to be cooled (gaseous helium, hydrogen,
liquid nitrogen or liquid neon) leaves the HTS 46 via line 60 and
is circulated through a counterflow heat exchanger 62 and a
compressor 64 before passing through the first auxiliary heat
exchanger 50 via line 66, and back through the counterflow heat
exchanger 62. An injection valve 68 permits some bleed off of fluid
from line 70 before the fluid passes in heat exchange relationship
with the GM cryocooler refrigerator 72. From here, the fluid
returns to the HTS equipment 46.
[0025] A separate closed loop is also established between the
cryocooler 44 and the second auxiliary heat exchanger 54.
Specifically, fluid from the cryocooler refrigerator 72 flows via
line 74 through the cryocooler compressor 76 and then through the
exchanger 54 before returning to the cryocooler refrigerator 72 via
line 78. With this arrangement, heat from the HTS equipment 46 and
cryocooler 44 is rejected to the ASU 42, again gaining the benefit
of using the cooler heat sink of the ASU.
[0026] FIG. 3 discloses still another arrangement where heat from
the HTS is rejected to the ASU. Here, nitrogen (liquid or gaseous)
or liquid air from the ASU 80 for an IGCC plant 81 is supplied as
the primary coolant to the HTS equipment 82. More specifically,
liquid N.sub.2, for example, flows out of the ASU 80 via line 84
through a pump and flow controller 86 in the otherwise conventional
cryocooler 88 and into the HTS equipment via line 90. The liquid is
returned to the ASU via line 92. This arrangement is particularly
useful where the HTS equipment also uses liquid for cooling, and
little effect is seen on the ASU where the liquid is returned at a
slightly higher temperature.
[0027] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims. For
example, a pulse-tube refrigerator or Sterling-cycle refrigerator
may also be employed as the cryocooler in the described system.
* * * * *