Note: Descriptions are shown in the official language in which they were submitted.
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METHODS AND SYSTEMS FOR CO2 CONDENSATION
BACKGROUND
TECHNICAL HELD
[WWII The present disclosure relates to methods and systems for carbon
dioxide (CO2) condensation iisirm magneto-caloric cooling. More particularly,
the
present disclosure relates to methods and systems for CO2 condensation in an
intercooled compression and pumping train using magneto-caloric cooling.
DISCUSSION OF RELATED ART
100021 Power generating .processes that are based on combustion of carbon
containing fuel typically produce CO" as a byproduct. It may be desirable to
capture
or otherwise separate the CO2 from the gas mixture to prevent the release of
CO2 into
the environment and/or to utilize CO2 in the power generation process or in
other
processes. It may be further desirable to liquefy/condense the separated CO2
to
facilitate transport and storage of the separated CO2. CO2 compression,
liquefaction
and pumping trains may be .used to liquefy CO2 for desired end-use
applications.
However, _methods for condensation/liquefaction of CO2 may be enemy intensive.
10003] Thus, there is a need for efficient methods and systems for
condensation of CO.?. Farther, there is a need for efficient methods and
systems for
condensation of CO2 in intercooled compression and pumpity, trains.
'BRIEF DESCRIPTION
100041 In accordance with one aspect of the present invention, a method
of
condensing carbon dioxide (COO from a CO2 stream is provided,. The method
includes (I) compressing and cooling the CO2 stream to form a partially cooled
CO.)
stream, wherein the partially cooled CO2 stream is cooled to a first
temperature. The
method includes (it) cooling the partially cooled CO2 stream to a second
temperature
by magneto-caloric cooling to ftwm a cooled CO2 stream. The method further
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includes (iii) condensing at least a portion of CO2 in the cooled CO2 stream
at the
second temperature to form a condensed CO2 stream.
[00051 In accordance
with another aspect of the present invention a method of
condensing carbon dioxide (CO2) from a CO2 stream is provided. The method
Includes (i) cooling the CO2 stream in a first cooling .staee comprising a
first heat
exchanger to form a first partially cooled CO2 stream. The method further
includes
(ii) compressing the first partially cooled CO2 stream .to form a .first
compressed CO2
stream. The .method further includes (iii) cooline the first compressed CO,
stream in
a second cooling stage comprising a second beat exchanger to form a second
partially
cooled CO2 stream. The method further includes (iv) compressing the second
partially cooled CO2 stream to .form a second compressed CO2 stream. The
method
further includes (v) cooling the second compressed CO? stream to a first
temperature
in a third cooling stage comprising a third heat exchanger to form a partially
cooled
CO2 stream. The method further includes (vi) cooling the partially cooled CO2
stream
to a second temperature by magneto-caloric cooling, to form a. cooled CO2
stream,
The method further includes (vii) condensing at least a portion of CO2 in the
cooled
CO2 stream at the second temperature to :form a condensed CO2 stream.
WW1 In accordance
with yet another aspect of the present invention, a
system for condensing carbon dioxide CO2)( from a CO2
stream is provided. The
system includes (.1) one or more compression stages configured to receive the
CO2
stream. The system further includes (JO one or more cooling stages in fluid
communication with the one or more compression stages, wherein a combination
of
the one or more compressive stages and the one or more cooling stages is
configured
to compress and cool the CO2 stream to a first temperature to form a partially-
cooled
CO2 stream. The system further includes (iii) a magneto-caloric cooling stage
configured to receive the partially-cooled C.02 stream and cool the partially-
cooled
CO2 stream to a second temperature to form a cooled CO2 stream. The system
further
includes (iv) a condensation stage configured to condense a .portion of CO2 in
the
cooled CO2 stream at the second temperature, thereby condensing CO, from the
cooled compressed CO2 stream to form a condensed CO2 stream.
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[00071 Other enibodiments, aspects, features, and advantages of the
invention
will become apparent to those of ordinary skill in the art from the following
detailed
description, the accompanying drawings, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
10008] These and other features, aspects, and advantages of the present
invention will become better understood when the thilowing, detailed
description is
read with reference to the accompanying drawings in which like characters
represent
like parts throughout the drawings, wherein:
100091 FIG .1 is a flow chart for a method of CO2 condensation from a CO2
stream, in accordance with one embodiment of the invention.
[00101 FIG. 2 is a flow chart for a method of CO2 condensation from a CO2
stream, in accordance with one embodiment of the invention.
[00111 FIG. 3 is a block diagram of a system for CO2 condensation from a
CO2 stream, in accordance with one embodiment of the invention.
[00121 FIG, 4 is a block diagram of a system for CO2 condensation .from a
CO2 stream, in accordance with one embodiment of the invention.
10013] FIG. 5 is a block diagram of a system for CO2 condensation from a
CO2 stream, in accordance with one embodiment of the invention.
100141 FIG, 6 is a block diagram of a system for CO2 condensation from a.
CO2 stream, in accordance with one embodiment of the invention.
100151 FIG, 7 is a block diagram of a system for CO2 condensation from a.
CO2 stream, in accordance with one embodiment of the invention..
100161 FIG. 8 is a block diagram of a system for CO2 condensation from a.
CO2 stream, in accordance with one embodiment of the invention..
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[00171 FIG. 9 is a block diagram of a system for CO2 condensation from a
CO2 Stream, in accordance with one embodiment of the invention
[00181 FIG. 10 is a pressure versus temperature diagram for CO2.
DETAILED 'DESCRIPTION
[00191 As discussed in detail below, embodiments of the present invention
.include methods and systems suitable for CO2 condensation. As noted earlier,
liquefying and pum.pinti of CO2 may require high energy input For example, a
pressure of approximately 60 bar may be required to liquefy CO2 at 20 C. In
some
embodiments. an intermediate magnetic cooling step advantageously lowers the
CO2
temperature to less than 0 C. significantly reducing the required work of the
overall.
system, In some embodiments, depending on the coefficient of performance of
the
mauneto-ealoric coolinu system, an overall efficiency improvement of about 10
percent to about 15 percent may be possible using the methods and systems
described
herein.
100201 Approximating language, as used herein throughout the
specification
and claims, may be applied to modify any quantitative representation that
could
permissibly vary without resulting in a change .in the 'basic function to
which it is
related. Accordingly, a value modified by a term or terms, such as "about", is
not
limited to the precise value specified. In some instances, the approximating
language
may correspond .to the precision of an instrument for measuring the value.
1002-11 in the following specification and the claims, the singular forms
"a",
"an" and 'the" include plural referents unless the context clearly dictates
otherwise.
100221 In one embodiment, as shown in Figures 1 and 3, a method 10 for
condensing carbon dioxide from a CO2 stream is provided. The term "CO,
stream",
as used herein, refers to a stream of CO2 gas mixture emitted as a result of
the
processing of fuels, such as, natural gas, biomass, gzsoline, diesel fuel,
coal, oil shale,
fuel oil, tat sands, and combinations thereof In some embodiments, the CO2
stream
includes a CO2 stream emitted from a gas turbine. In particular embodiments,
the
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CO2 stream includes a CO2 gas mixture emitted from a coal or natural gas-fired
power
plant
[0023j In some embodiments, the CO2 stream further includes one more of
nitrogen, nitrogen dioxide, oxygen,. or water vapor. In some embodiments, the
CO2
stream further includes impurities or pollutants, examples of which include,
but are
not limited to, nitrogen, nitrogen oxides, sulfur oxides, carbon monoxide,
hydrogen
sulfide, imbumt hydrocarbons, particulate matter, and combinations thereof. In
particular embodiments, the CO2 stream is substantially free of the impurities
or
pollutants. In particular embodiments, the CO2 stream essentially includes
carbon
dioxide.
[0024j In some embodiments, the amount of impurities or pollutants in the
CO2 stream is less than about 50 mole percent. In some embodiments, the amount
of
impurities or pollutants in the CO2 stream is less than about 20 mole percent.
In some
embodiments, the amount of impurities or pollutants in the CO? stream is in a
range
from about 10 mole percent to about 20 mole percent. in some embodiments, the
amount of impurities or pollutants in the CO2 stream is less than about 3 mole
percent.
[00251 In one embodiment, the method includes receiving a CO2 stream 101,
as indicated in Fig. 3, from a hydrocarbon processing, combustion,
gasification or a
similar power plant not shown). As indicated in Figures 1 and 3, at step 11,
the
method 10 includes compressing and cooling the CO2 stream 101 to form a
partially
cooled CO2 stream 201. In some embodiments, the CO2 stream 101 may be
compressed using or more compression stages 120. In some embodiments, the CO2
stream may be cooled using or more cooling stages 110.
[00261 In some embodiments, the CO2 stream 101 may be compressed to a
desired pressure by using one or more compression stages, as indicated by 120
in Fig.
3, As indicated in Fig. 3, the compression stage 120 may further include one
or more
compressors, such as, 121 and 122, in some embodiments, It should be noted
that in
Fig. 3, the two compressors 121 and 122 are shown as an exemplaty embodiment
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only and the actual number of compressors and their .individual configuration
may
vary depending on the end result desired. In one embodiment, the CO2 stream
101
may be compressed to a pressure and temperature desired for the magnetic
cooling
and condensation steps 12 and. 13, respectively. In some embodiments, the CO2
stream 101 may he compressed to a pressure in a range from about 10 bar to
about 60
her prior to the magnetic cooling step 12. In particular embodiments, the CO2
stream
101 may be compressed to a pressure in a range from about 20 bar to about 40
bar
prior to the magnetic cooling step 12.
[0027j In some embodiments, the CO2 stream 101 may be cooled to a desired
temperature by using one or more codling stages, as indicated by 110 in Fig.
3. As
indicated in Fin. 3, the cooling stage 110 may further include one or more
heat
exchangers, such as, III. 112 arid 113, in some embodiments. It should be
noted that
in Fig. 3, the three heat exchangers 111, 112, and 113 are shown as an
exemplary
embodiment (Ay and the actual number of heat exchangers and their individual.
configuration may Vary depending Oil the end result desired. In some
embodiments,.
one or more of the heat exchangers may be cooled using a warm medium, hi some
embodiments, one more of the heat exchangers may be cooled using cooling air,
cooling water, or 'both, as indicated by. 115 in Fig. 3. In some embodiments,
the
cooling stage may timber include one or more intercoolers to cool the exhaust
gas
stream 101 without affecting the pressure.
I9O2SJ it should be further noted that in Fig. 3, the configuration of
cooling
stage. 110 and compression stage 120 is shown as an exemplary embodiment only
and
the actual confi$,Turation may vary depending on the end result desired. For
example,
in some other embodiments, the method may include cooling the CO2 stream in a
heat
exchanger 111 prior to compressing the CO2 stream in a compressor 121 (not
shown).
[0029] In some embodiments, the method further includes cooling the CO)
stream 101 to a first temperature by expanding the CO2 stream in one Of more
expanders 12:3, as indicated in Fig, 8. In some embodiments the method
includes an
expansion step that decreases the pressure of the CO2 stream 101 from absolute
pressure levels greater than about 20 bar to pressure levels of around 20 bar,
thereby
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decreasing the temperature of the CO2 stream 101 to values lower than that may
be
.reached by air or water cooling. Without being bound any theory, it is
believed that
hy employing .the expansion step, the overall duty of the magneto-caloric
cooling step
12 may he reduced, as the inlet temperature of the partially-cooled CO2 stream
to the
magneto-ealoric step may be lower than that without an expansion step. in some
embodiments, the work extracted in the expansion step may be .fiather used for
the
magneto-caloric cooling step 1.2.
[0030] in one embodiment, the CO2 stream 101 may be cooled to a
temperature and pressure desired for the magnetic cooling and condensation
steps 1.2
and 13. In one embodiment, the method includes compressing and cooling the CO2
stream 101 to .tbrin a partially cooled CO2 stream 201, as indicated In Fig.
3. In one
embodiment, the .method further includes cooling the CO2 stream 101 to a first
temperature by expanding the CO2 stream in one or more expanders 123 to form
the
partially cooled CO2 stream 201, as indicated in Fig. S.
100311 In one embodiment, the method includes cooling the partially
cooled
CO2 stream 201 to a. first temperature. In some embodiments, the partially
cooled
CO2 stream 201 may be cooled to a temperature .in a range from about 5 degrees
Celsius to about 35 degrees Celsius, prior to the magnetic cooling step 12, in
.particular embodiments, the partially cooled CO2 stream .201 .may be cooled
to a
temperature in a range from about 1.0 degrees Celsius .to about 25 degrees
Celsius,
prior to the magnetic cooling step 12.
100321 As noted earlier, in the absence of an additional magnetic cooling
step,
CO2 in the partially cooled CO2 stream 201 is typically liquefied at a
temperature in a
range from about 20 degrees Celsius to about 25 degrees Celsius. The
condensation
temperature is determined by the temperature of the cooling medium, which can
be
cooling water or air. As shown in Fig. 10, at a condensation temperature in a
range
from about 20 degrees Celsius to about 25 degrees Celsius, an Absolute
pressure of
approximately 60 bar is required to liquefy C07. In contrast, by cooling the
CO2
stream to a. temperature in a range from about -25 degrees Celsius to about 0
degrees
248568
Celsius, lower pressure may be advantageously used for condensing CO2 from the
partially cooled CO2 stream 201.
[0033] In one embodiment, the method further includes, at step 12,
cooling the
partially cooled CO2 stream 201 to a second temperature by magneto-caloric
cooling
to form a cooled CO2 stream 302, as indicated in Figures 1 and 3. In one
embodiment, the method includes cooling the partially-cooled CO2 stream 201
using a
magneto-caloric cooling stage 200, as indicated in Fig. 3.
[0034] In some embodiments, a magneto-caloric cooling stage 200
includes a
heat exchanger 212 and an external magneto-caloric cooling device 211. In some
embodiments, the magneto-caloric cooling device 211 is configured to provide
cooling to the heat exchanger 212, as shown in Fig. 3.
[0035] In one embodiment, the magneto-caloric cooling device 211
includes a
cold and a hot heat exchanger, a permanent magnet assembly or an induction
coil
magnet assembly, a regenerator of magneto-caloric material, and a heat
transfer fluid
cycle. In one embodiment, the heat transfer fluid is pumped through the
regenerator
and the heat exchanger by a fluid pump (not shown).
[0036] In one embodiment, the magneto-caloric cooling devices works on
an
active magnetic regeneration cycle (AMR) and provides cooling power to a heat
transfer fluid by sequential magnetization and demagnetization of the magneto-
caloric
regenerator with flow reversal heat transfer flow. In some embodiments, the
sequential magnetization and demagnetization of the magneto-caloric
regenerator may
be provided for by a rotary set-up where the regenerator passes through a bore
of the
magnet system. In some other embodiments, the sequential magnetization and
demagnetization of the magneto-caloric regenerator may be provided for by a
reciprocating linear device. An exemplary magnet assembly and magneto-caloric
cooling device are described in US Patent Application Publication No.
2010/0212327 Al.
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[00371 In some embodiments, the heat at the hot heat exchanger may be
delivered to the ambient environment. In some other embodiments, the heal at
the hot
heat exchanger may be delivered to the return flow of the condensed and
liquefied
CO2 after the pumping of the liquid CO2, as described herein later.
[00381 As noted earlier, the magneto-caloric cooling stage further
includes a
heat exchanger 212, wherein the magneto-caloric cooling device 211 is
configured to
provide cooling to the heat exchanger 212. In one embodiment-, the heat
exchanger
212 is in fluid communication with the one or more cooling stages 110 and the
one or
more compression stages 120. In one embodiment, the heat exchanger 212 is in
fluid
communication with the partially cooled CO2 stream 201 generated after the
compression and cooling step 11.
100391 In some embodiments, the magneto-caloric cooling device 211 is
configured to provide cooling to the heat exchanger 212 such that the
partially cooled
CO2 stream 201 is cooled to the second temperature. In one embodiment, the
second
temperature is in a range of from about 0 degrees Celsius to about-25 degrees
Celsius.
In one embodiment, the second temperature is in a range of from about 5
degrees
Celsius to about-20 degrees Celsius. As noted earlier, the step 13 of cooling
the
partially-cooled CO2 stream in the magneto-caloric cooling stage results in a
cooled
CO2 stream.
[00401 In some embodiments, the magneto-caloric cooling device 211 is
configured to provide cooling to the heat exchanger 212 such that the
partially cooled
CO2 stream 201 is cooled to the second temperature, such that CO2 condenses
from
the cooled CO2 stream. As noted earlier, the method includes compressing the
CO2
stream 101 to a pressure in a range from about 20 bar to about 40 bar, in some
embodiments. As indicated in Fig. 10, at a pressure level of 40 bar, the CO2
condenses at a temperature of 5 C. Further, as indicated in Fig. 10, at a
pressure level
of 20 bar, the CO2 condenses at a temperature of -20 C.
[00411 In one embodiment, the method further includes, at step 13,
condensing at least a portion of CO2 in the cooled CO2 stream at the second
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temperature, thereby condensing CO2 from the cooled CO? stream to form a
condensed CO2 stream 302. In one embodiment, the method includes condensing at
least a portion of CO, in the cooled CO? stream at a pressure in a range of
from about
20 bar to about 60 bar. In one embodiment, the method includes condensing at
least a
portion of CO2 in the cooled CO2 stream at a pressure in a .range of from
about 20 bar
to about 40 bar. Accordingly, the method of the present invention
adyantageously
allows for condensation of CO2 at a lower pressure, in some embodiments.
[0042] In some embodiments, the method includes performing the steps of
cooling the partially cooled CO2 streaM to form a cooled CO2 stream 12 and
condensing CO2 from the cooled CO2 stream 13 simultaneously. In some other
embodiments, the method includes performing the steps of cooling the
partially:
cooled CO2 stream to form a cooled CO.) stream 12 and condensing CO2 from the
cooled CO2 stream 13 sequentially.
10043] As indicated in Fig. 3, in some embodiments, a cooled CO2 stream
may be generated from the partially cooled CO2 stream 201 in the heat
exchanger
212. In such embodiments, a. portion of CO2 from the cooled. CO2 stream
condenses
.in the heangenerator itself forming a. condensed CO) stream 302, as indicated
in Fig,
3,
[00441 In some other embodiments, as indicated in Fig, 4, a cooled CO2
stream 30.1 is generated from the partially coo-led CO2 stream 201 in the heat
exchanger 212. The method further includes transferring the cooled CO2 stream
301
to a. condenser 213, as indicated in Fig. 4, In such embodiments, a portion of
CO2
from the cooled CO2 stream 301 condenses in the, condenser 213 and :forms a
condensed CO2 stream 302, as indicated in Fig. 4.
[0045] in some embodiments, the method. includes condensing at: least
about
95 weight percent of CO2 in the CO2 stream 101 to form the condensed CO2
stream
302. in some embodiments, the method includes condensing at least about 90
weight
.percent of CO2 in the. CO2 stream 101 to fonn the condensed CO2 stream 302.
In
some embodiments, the method includes condensing 50 weight percent: to about
90
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weight percent of CO?, in the CO2 stream 101 to form the condensed CO2 stream
302.
In some. embodiments, the method includes condensing at least about 99 weight
percent of CO2 in the CO2 stream 101 to form the condensed CO2 stream 302.
100461 hi some embodiments, as noted earlier, the CO2 stream 101 further
includes one or more components in addition to carbon dioxide. In some
embodiments, the method further optionally includes generating a lean stream
(indicated by dotted arrow 2.02) after the steps of mail.neto-calorie cooling
(step 12)
and CO2 condensation (step 13). The term "lean stream" 202. refers to a stream
in
which the CO2 content is lower than that of the CO2 content in the CO2 stream
En,
in some embodiments, as noted earlier, almost all of the CO2 in the CO2 stream
is
condensed in the step 13. In such embodiments, the lean CO2 stream is
substantially
free of CO2. In some other embodiments, as noted. earlier, a portion of the
CO2
stream may not condense in the step 13 and the lean stream may include -
uncondensed
CO2 as mixture
100471 In some embodiments, the lean stream 202 may- include one or more
non-condensable components, which may not condense in the step 13. In some
embodiments, the lean stream 202 may include one or more liquid components. in
such enibodiments, the lean stream may be further configured to be in fluid
communication with a liquid-gas separator. In some embodiments, the lean
stream
202 may include one or more of nitrogen, oxygen, or sulfur dioxide.
100481 In some embodiments, the method may further include dehumidifying
the CO2 stream 101 before step .11.. In some embodiments, the method may
further
include dehumidifying the partially cooled CO2 stream 201 after step 11 and
before
step 12. In some embodiments, the system 100 may further include a
dehumidifier
configured to be in flow- communication (not shown) with the CO2 stream 101.
in
some embodiments, the system 100 may further include a. dehumidifier
confieured to
be in flow communication (not shown) with the CO2 stream 101.
1:00491 In some embodiments, the method further includes circulating the
condensed CO, stream 302 to one or more cooling stages used for cooling the
CO2
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stream. As indicated in Fig. 5, the method further includes circulating the
condensed
CO2 stream to a heat exchanger 113 via a circulation loop 303. In such
embodiments,
the method further includes a recuperation step where the condensed CO2
stream. is
circulated back to further cool the partially cooled CO2 stream .201 before
the
magneto-caloric cooling step 12, in some embodiments, the recuperation step
may
increase the efficiency of the magneto-caloric step.
100501 In some embodiments, the recuperation of condensed CO2 stream to
the heat exchanger 113 may result in cooling of the partially cooled CO2
stream 201
below the temperature required for condensation of CO2. In some embodiments,
the
method may further include condensing the CO2 in the partially cooled CO2
stream
201 to fonn a recuperated condensed stream 501, as indicated in Fig. 5.
[00511 in some embodiments, the method further includes increasing a
pressure of the condensed CO2 stream 302 using a pump 300, as indicated in
Fig, 3.
In embodiments including a recuperation step, the method may further include
increasing a pressure of the recuperated condensed CO2 stream 501 using a pump
300,
as indicated in Fig. 5. In some embodiments, the method includes increasing a
pressure of the condensed CO2 stream 302 or the recuperated condensed CO2
stream
502 to a pressure desired for CO2 sequestration or end-use. in some
embodiments, the
method includes increasing a pressure of the condensed CO2 stream 302 or the
recuperated condensed CO2 stream 502 to a pressure in a range from about 150
bar to
about 180 bar.
190521 In some embodiments, the method further includes generating a
pressurized CO2 stream 401 after the pumping step. In some embodiments, the
method further includes generating a supercritical CO2 stream 401 after the
pumping
step. hi some embodiments, as noted earlier, the pressurized CO2 stream 401
may be
used for enhanced oil recover, CO2 storage, or CO2 sequestration.
[00531 In some embodiments, a system 100 for condensing carbon dioxide
(CO2) from a CO2 stream 101 is provided, as illustrated in Figures 3-9. In one
embodiment, the system 100 includes one or more compression stages 120
configured
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to receive the CO. stream 101. The system 100 further includes one or more
cooling
stages 1.10 in fluid communication with the one or more compression. stages
120. in
one embodiment, a combination of the one or more compression. stages 120 and
the
one or more cooling stages 1 10 is configured to compress and cool the CO2
stream
10-i to a -first temperature to form a. partially-cooled CO2 stream 201.
[00541 In one embodiment, the system 100 further includes a magneto-
caloric
cooling stage IX) configured to receive the partially-cooled CO2 stream 201
and cool.
the partially-cooled CO-, stream 201 to a. second temperature to form a cooled
CO2
stream 301. As noted earlier, the magneto-caloric cooling stage 200 further
includes a
heat exchanger 212. Wherein the magneto-caloric cooling device 211 is
configured to
provide cooling to the heat exchanger 212. In one embodiment, the heat
exchanger
212 is in fluid communication with the one or more cooling stages 110 and the
one or
more compression stages 120.
10055] As noted earlier, in some embodiments, the heat exchanger 212 is
configured to condense a portion of CO2 in the partially cooled CO2 stream 201
to
form the condensed CO2 stream 302. In some other embodiments, the system 100
further includes a condensation stage 213 configured to condense a portion of
CO2 in
the cooled CO2 stream 301 at the second temperature, thereby condensing CO2
from
the cooled CO2 strewn 301 to form a condensed CO2 stream. 302.
[00561 In some embodiments, the system 100 further includes a pump 300
configured to receive the condensed CO2 stream 302 and increase the .pressure
of the
condensed CO2 stream 302. In some embodiments, the system further includes a.
circulation loop 303 configured to circulate a portion of the condensed CO2
stream
302 to the one or more cooling stages 110.
[0057] With the foregoing in .mind, systems and methods .for condensing
CO2
from a CO2 stream, according to some exemplary embodiments of the invention,
are
further described herein. Turning now to Figures 2 and 3, in one embodiment, a
.method 20 of condensing carbon dioxide from a. CO2 stream 101 is provided. In
one
embodiment, the method includes, at step 21, cooling the CO? stream 101 in a
first
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cooling stage including a first heat exchanger 111 to fOrm a first partially
cooled CO2
stream 102. In one embodiment, the method includes, at step 22, compressing
the
first partially cooled CO2 stream 102 in a first compressor 1.21 to form a
first
compressed CO2. stream 103. In one embodiment, the method includes, at step
23,
cooling the first compressed CO2 stream 103 in a second cooling stage
including a
second heat exchanger 112 to form a second partially cooled CO-.. stream 104.
In one
embodiment, the method includes, at step 24, compressing the second partially
cooled
CO2 stream 104 in a second compressor 122 to form a second compressed CO2
stream
105. In one embodiment, the method includes, at step 25, cooling the second
compressed CO2 stream 105 to a first temperature in a third cooling stage
comprising
a third heat exchanger 113 to form a partially cooled CO2 stream 201 õ
[005S1 In one embodiment, the method 20 includes, at step 26, cooling the
partially cooled CO2 stream 201 to a second temperature by magneto-caloric
cooling
using a magneto-caloric cooling stage 200 to form a cooled CO2 stream (not
shown).
In some embodiments, a magneto-calorie cooling stage 200 includes a heat
exchanger
212 and an external magneto-caloric cooling device 211. In some embodiments,
the
magneto-caloric cooling device 211 is configured to provide cooling to the
heat
exchanger 212, as indicated in
[00591 In one embodiment, the .method includes, at step 27, condensing at
least a portion of CO) in the cooled CO2 stream at the second temperature,
thereby
condensing CO? from the cooled CO2 stream to form a condensed CO2 stream 302.
As noted earlier, in some embodiments, a cooled CO2 stream is generated from
the
partially cooled CO2 stream 201 in the heat exchanger 212. In such
embodiments, a
portion of CO2 from the cooled CO2 stream condenses in the heat-generator
itself
forming a condensed CO, stream 302, as indicated in Fig. 3.
[00601 In some embodiments, the method further includes increasing a
pressure of the condensed CO2 stream 302 using a pump 300, as indicated in
Fig. 3.
In some embodiments, the method further includes generating a pressurized CO2
stream 401 after the pumping step. In some embodiments, as noted earlier, the
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pressurized CO2 stream 401 .may be used for enhanced oil recovery. CO2
storage, or
CO2 sequestration,.
[0061 J Turning now to Fig. 4,, in one embodiment, a method and a system
for
condensing CO2 from a CO2 stream 101 is .provided. The method and system is
similar to the system and method illustrated in Fig, 3, with the addition that
the
method further includes transferring, the cooled CO2 stream 301 to a condenser
213, as
indicated in Fig. 4. In such embodiments, a portion of CO? from the cooled CO2
stream 301 condenses in the condenser 213 and forms a condensed CO2 stream
302,
as indicated in Fig. 4,
[0062] Turning now to Fig. & in one embodiment, a method and a system for
condensing CO2 from a CO2 stream 101 is provided. The method and system is
similar to the system and method illustrated in Fig. 3, with the addition that
the
method further includes circulating a portion of the condensed CO2 stream 302
to the
third heat exchanger 113 via a circulation ioop 303. As noted earlier, in some
embodiments,, the recuperation of condensed CO2 stream to the heat exchanger
113
may result in cooling of the second compressed CO2 stream .105 below the
temperature required for condensation of CO?. In some embodiments, the method
may further include condensing the CO? in the second compressed CO2 stream 105
to
form a recuperated condensed CO2 stream 501, as indicated in Fig. 5.
[0063 Turning now to Fig. 6, in one embodiment, a method and .sy stem
for
condensing CO2 from a CO-, stream 101 is .provided. The method and system is
similar to the system and method illustrated in Fig. 4, with the addition that
the
method limber includes circulating a portion of the condensed CO2 stream to
the third
heat exchanger 1.13 via a circulation loop 301 As noted earlier, in some
embodiments, the recuperation of condensed CO2 to the heat exchanger 11.3 may
result in cooling of the second compressed CO2 stream 105 below the
temperature
required for condensation of CO2. In some embodiments, the method may further
include condensing the CO2 in the second compressed CO2 stream 105 to form a
recuperated condensed CO2 stream 501, as indicated in 'Fig. 6.
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[00641 Turning now to Fie. 7, in one embodiment, a method and a system
for
condensing CO2 from a CO2 stream 101 is -provided. The method and system is
similar to the system and method illustrated in Fig. 3, with the addition that
the
method further includes circulating a portion of the pressurized CO., stream
401 to the
third heat exchanaer 113 via a. circulation loop 403. As noted earlier, in
some
embodiments, the recuperation of pressurized CO2 stream 401 to the third heat
exchanger 1.1.3 may result in cooling of the second compressed CO, stream 1.05
below
the temperature required for condensation of CO2. in some embodiments, the
method
may further include condensing the CO2 in the second compressed CO2 stream 105
to
form a recuperated condensed CO2 stream 501, as indicated in Fig. 7.
[00651 'Turning now to Fig. 8, in one embodiment, a method and a system
for
condensing CO2 from a CO2 stream 101 is illustrated. The method and system is
similar to the system and method illustrated in Fig. 3, with the addition that
the
method further includes forming a. third partially cooled CO, stream 106 in
the third
heat exchanger 113. The method further includes cooling the third partially
cooled
CO2 stream 106 to a first temperature 'by expanding the. third partially
cooled CO,
stream 106 in one or more expanders 123, before the magneto-caloric cooling
step, to
form the partially-cooled CO2 stream 201, as indicated in Fig. 8.
[00661 Turning now to Fig. 9, in one embodiment, a method. and a system
for
condensing CO2 from a CO2 stream 10.1 is illustrated. The method and gystem is
similarto the system and method illustrated in Fig. 8, with the addition that
the third
tooling stage further comprises a fourth heat exchanger 114, and the method
further
includes circulating a portion of the pressurized CO2 stream 401 to the
.fourth heat
exchanger 114 via, a. circulation loop 403. The method further includes
forming a
fourth partially cooled CO2 stream 107 after the expansion step and
transferring the
fourth partially cooled CO2 stream 107 to the fourth heat exchanger 114. As
noted
earlier, in some embodiments, -the recuperation of pressurized CO2 stream 401
to the
fourth heat exchanger 114 may result in cooling of the fourth partially cooled
CO-,
stream 107 below the temperature required for condensation of CO2. In some
embodiments, the method. may further include condensing the CO2 in the fourth
248568
partially cooled CO2 stream 107 to form a recuperated condensed CO2 stream
501, as
indicated in Fig. 9.
[0067] As noted earlier, some embodiments of the invention
advantageously
allow for cooling of the supercritical CO2 to lower temperatures and
subsequent
condensation at lower pressures than those available through conventional
cooling
methods, such as, vapor compression. Without being bound by any theory, it is
believed that compression of supercritical CO2 may be less efficient than
pumping
liquid CO2. Thus, in some embodiments, the method reduces the penalty on the
less-
efficient CO2 compression step. In some embodiments, the method may reduce the
overall penalty for CO2 liquefaction and pumping by improving the efficiency
of the
compression and pumping system. In some embodiments, the magneto-caloric
cooling stage may reduce the penalty by more than 10%. In some embodiments,
the
magneto-caloric cooling stage may reduce the penalty by more than 20%. In some
embodiments, the overall plant efficiency may be improved by using one or more
of
the method embodiments, described herein.
[0068] Further, some embodiments of the invention advantageously allow
for
improved range of operability of CO2 compression and liquefaction systems. In
conventional CO2 compression and liquefaction systems, the ambient temperature
of
the cooling air or cooling water may limit the range of operability.
Supercritical CO2
may not liquefy at temperatures greater than about 32 C, the critical
temperature of
CO2. Thus, when ambient temperatures are above 30 C, liquefaction of CO2 may
be
difficult without additional external cooling. In some embodiments, the
magnetic
cooling step may advantageously allow cooling of CO2 to the subcritical range,
thereby enabling the operability of the compression and liquefaction systems
under
any ambient conditions.
[0069] This written description uses examples to disclose the
invention,
including the best mode, and also to enable any person skilled in the art to
practice the
invention, including making and using any devices or systems and performing
any
incorporated methods. The patentable scope of the invention may include other
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248568
examples that occur to those skilled in the art in view of the description.
Such other
examples are intended to be within the scope of the invention.
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