METHODS AND SYSTEMS FOR CO2 CONDENSATION

Abstract

In accordance with one aspect of the present invention, methods of condensing carbon dioxide (CO2) from a CO2 stream are provided. The method includes (i) compressing and cooling the CO2 stream to form a partially cooled CO2 stream, wherein the partially cooled CO2 stream is cooled to a first temperature. The method includes (ii) cooling the partially cooled CO2 stream to a second temperature by magneto-caloric cooling to form a cooled CO2 stream. The method further includes (iii) condensing at least a portion of CO2 in the cooled CO2 stream to form a condensed CO2 stream. Systems for condensing carbon dioxide (CO2) from a CO2 stream are also provided

Description

BACKGROUND

1. Technical Field

The present disclosure relates to methods and systems for carbon dioxide (CO₂) condensation using 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.

2. Discussion of Related Art

Power generating processes that are based on combustion of carbon containing fuel typically produce CO₂ 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 energy intensive.

Thus, there is a need for efficient methods and systems for condensation of CO₂. Further, there is a need for efficient methods and systems for condensation of CO₂ in intercooled compression and pumping trains.

BRIEF DESCRIPTION

In accordance with one aspect of the present invention, a method of condensing carbon dioxide (CO₂) from a CO₂ stream is provided. The method includes (i) compressing and cooling the CO₂ stream to form a partially cooled CO₂ stream, wherein the partially cooled CO₂ stream is cooled to a first temperature. The method includes (ii) cooling the partially cooled CO₂ stream to a second temperature by magneto-caloric cooling to form a cooled CO₂ stream. The method further includes (iii) condensing at least a portion of CO₂ in the cooled CO₂ stream at the second temperature to form a condensed CO₂ stream.

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 stage 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) cooling the first compressed CO₂ stream in a second cooling stage comprising a second heat 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 CO₂ 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.

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 (i) one or more compression stages configured to receive the CO₂ stream. The system further includes (ii) one or more cooling stages in fluid communication with the one or more compression stages, wherein a combination of the one or more compression 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 CO₂ 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 CO₂ from the cooled compressed CO₂ stream to form a condensed CO₂ stream.

Other embodiments, 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

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a flow chart for a method of CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 2 is a flow chart for a method of CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 3 is a block diagram of a system for CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 4 is a block diagram of a system for CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 5 is a block diagram of a system for CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 6 is a block diagram of a system for CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 7 is a block diagram of a system for CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 8 is a block diagram of a system for CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 9 is a block diagram of a system for CO₂ condensation from a CO₂ stream, in accordance with one embodiment of the invention.

FIG. 10 is a pressure versus temperature diagram for CO₂.

DETAILED DESCRIPTION

As discussed in detail below, embodiments of the present invention include methods and systems suitable for CO₂ condensation. As noted earlier, liquefying and pumping 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 magneto-caloric cooling system, an overall efficiency improvement of about 10 percent to about 15 percent may be possible using the methods and systems described herein.

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.

In the following specification and the claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

In one embodiment, as shown in FIGS. 1 and 3, a method 10 for condensing carbon dioxide from a CO₂ stream is provided. The term “CO₂ 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, gasoline, diesel fuel, coal, oil shale, fuel oil, tar sands, and combinations thereof. In some embodiments, the CO₂ stream includes a CO₂ stream emitted from a gas turbine. In particular embodiments, the CO₂ stream includes a CO₂ gas mixture emitted from a coal or natural gas-fired power plant.

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, unburnt 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.

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 CO₂ 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 5 mole percent.

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 FIGS. 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.

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 exemplary embodiment 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 be compressed to a pressure in a range from about 10 bar to about 60 bar 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.

In some embodiments, the CO₂ stream 101 may be cooled to a desired temperature by using one or more cooling stages, as indicated by 110 in FIG. 3. As indicated in FIG. 3, the cooling stage 110 may further include one or more heat exchangers, such as, 111, 112 and 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 only and the actual number of heat exchangers and their individual configuration may vary depending on the end result desired. In some embodiments, one or more of the heat exchangers may be cooled using a cooling medium. In 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 further include one or more intercoolers to cool the exhaust gas stream 101 without affecting the pressure.

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 configuration 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).

In some embodiments, the method further includes cooling the CO₂ stream 101 to a first temperature by expanding the CO₂ stream in one or more expanders 123, 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 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 by employing the expansion step, the overall duty of the magneto-caloric cooling step 12 may be reduced, as the inlet temperature of the partially-cooled CO₂ stream to the magneto-caloric step may be lower than that without an expansion step. In some embodiments, the work extracted in the expansion step may be further used for the magneto-caloric cooling step 12.

In one embodiment, the CO₂ stream 101 may be cooled to a temperature and pressure desired for the magnetic cooling and condensation steps 12 and 13. In one embodiment, the method includes compressing and cooling the CO₂ stream 101 to form 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. 8.

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 10 degrees Celsius to about 25 degrees Celsius, prior to the magnetic cooling step 12.

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 CO₂. In contrast, by cooling the CO₂ stream to a temperature in a range from about −25 degrees Celsius to about 0 degrees Celsius, lower pressure may be advantageously used for condensing CO₂ from the partially cooled CO₂ stream 201.

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 FIGS. 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.

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.

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).

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 U.S. patent application Ser. No. 12/392,115, filed on Feb. 25, 2009, and incorporated herein by reference in its entirety for any and all purposes, so long as not directly contradictory with the teachings herein.

In some embodiments, the heat at the hot heat exchanger may be delivered to the ambient environment. In some other embodiments, the heat 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.

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.

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.

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.

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 temperature, thereby condensing CO₂ from the cooled CO₂ stream to form a condensed CO₂ stream 302. 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 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 advantageously allows for condensation of CO₂ at a lower pressure, in some embodiments.

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 CO₂ stream 12 and condensing CO₂ from the cooled CO₂ stream 13 sequentially.

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 heat-generator itself forming a condensed CO₂ stream 302, as indicated in FIG. 3.

In some other embodiments, as indicated in FIG. 4, a cooled CO₂ stream 301 is generated from the partially cooled 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.

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 form the condensed CO₂ stream 302. In some embodiments, the method includes condensing 50 weight percent to about 90 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 99 weight percent of CO₂ in the CO₂ stream 101 to form the condensed CO₂ stream 302.

In 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 202) after the steps of magneto-caloric 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 101. 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 gas mixture.

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 embodiments, 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.

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 configured to be in flow communication (not shown) with the CO₂ stream 101.

In some embodiments, the method further includes circulating the condensed CO₂ stream 302 to one or more cooling stages used for cooling the CO₂ 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.

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 form a recuperated condensed CO₂ stream 501, as indicated in FIG. 5.

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.

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. In some embodiments, as noted earlier, the pressurized CO₂ stream 401 may be used for enhanced oil recovery, CO₂ storage, or CO₂ sequestration.

In some embodiments, a system 100 for condensing carbon dioxide (CO₂) from a CO₂ stream 101 is provided, as illustrated in FIGS. 3-9. In one embodiment, the system 100 includes one or more compression stages 120 configured to receive the CO₂ stream 101. The system 100 further includes one or more cooling stages 110 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 110 is configured to compress and cool the CO₂ stream 101 to a first temperature to form a partially-cooled CO₂ stream 201.

In one embodiment, the system 100 further includes a magneto-caloric cooling stage 200 configured to receive the partially-cooled CO₂ stream 201 and cool the partially-cooled CO₂ 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.

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 stream 301 to form a condensed CO₂ stream 302.

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.

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 FIGS. 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 CO₂ stream 101 in a first 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 121 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 CO₂ 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.

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-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 indicated in FIG. 3.

In one embodiment, the method includes, at step 27, condensing at least a portion of CO₂ in the cooled CO₂ stream at the second temperature, thereby condensing CO₂ 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 CO₂ stream 302, as indicated in FIG. 3.

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 pressurized CO₂ stream 401 may be used for enhanced oil recovery, CO₂ storage, or CO₂ sequestration.

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 CO₂ from the cooled CO₂ stream 301 condenses in the condenser 213 and forms a condensed CO₂ stream 302, as indicated in FIG. 4.

Turning now to FIG. 5, 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 loop 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 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. 5.

Turning now to FIG. 6, in one embodiment, a method and 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. 4, with the addition that the method further includes circulating a portion of the condensed CO₂ stream to the third heat exchanger 113 via a circulation loop 303. As noted earlier, in some embodiments, the recuperation of condensed CO₂ to the heat exchanger 113 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.

Turning now to FIG. 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 CO₂ stream 401 to the third heat exchanger 113 via a circulation loop 403. As noted earlier, in some embodiments, the recuperation of pressurized CO₂ stream 401 to the third heat exchanger 113 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. 7.

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 CO₂ 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 CO₂ 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.

Turning now to FIG. 9, 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. 8, with the addition that the third cooling 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 CO₂ stream 107 below the temperature required for condensation of CO₂. In some embodiments, the method may further include condensing the CO₂ in the fourth partially cooled CO₂ stream 107 to form a recuperated condensed CO₂ stream 501, as indicated in FIG. 9.

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.

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.

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 is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A method of condensing carbon dioxide (CO2) from a CO2 stream, comprising: (i) compressing and cooling the CO2 stream to form a partially cooled CO2 stream, wherein the partially cooled CO2 stream is cooled to a first temperature;(ii) cooling the partially cooled CO2 stream to a second temperature by magneto-caloric cooling to form a cooled CO2 stream; and(iii) condensing at least a portion of CO2 in the cooled CO2 stream to form a condensed CO2 stream.

2. The method of claim 1, wherein step (iii) comprises 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 60 bar.

3. The method of claim 1, wherein step (iii) comprises 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.

4. The method of claim 1, wherein the first temperature is in a range of from about 5 degrees Celsius to about 35 degrees Celsius

5. The method of claim 1, wherein the second temperature is in a range of from about 0 degrees Celsius to about −25 degrees Celsius

6. The method of claim 1, wherein step (i) comprises cooling the CO2 stream using one or more cooling stages comprising one or more heat exchangers.

7. The method of claim 1, further comprising circulating a portion of the condensed CO2 stream to one or more cooling stages used for cooling the CO2 stream.

8. The method of claim 1, wherein step (i) comprises cooling the CO2 stream to the first temperature by expanding the CO2 stream in one or more expanders.

9. The method of claim 1, wherein step (ii) comprises cooling the partially-cooled CO2 stream using a rotary magneto-caloric cooling device.

10. The method of claim 1, further comprising increasing a pressure of the condensed CO2 stream using a pump to form a pressurized CO2 stream.

11. A method of condensing carbon dioxide (CO2) from a CO2 stream, comprising: (i) cooling the CO2 stream in a first cooling stage comprising a first heat exchanger to form a first partially cooled CO2 stream;(ii) compressing the first partially cooled CO2 stream to form a first compressed CO2 stream;(iii) cooling the first compressed CO2 stream in a second cooling stage comprising a second heat exchanger to form a second partially cooled CO2 stream;(iv) compressing the second partially cooled CO2 stream to form a second compressed CO2 stream;(v) cooling the second compressed CO2 stream to a first temperature in a third cooling stage comprising a third heat exchanger to form a partially cooled CO2 stream;(vi) cooling the partially cooled CO2 stream to a second temperature by magneto-caloric cooling to form a cooled CO2 stream; and(vii) condensing at least a portion of CO2 in the cooled CO2 stream at the second temperature, thereby condensing CO2 from the cooled CO2 stream to form a condensed CO2 stream.

12. The method of claim 11, further comprising circulating a portion of the condensed CO2 stream to the third heat exchanger.

13. The method of claim 11, wherein the third cooling stage further comprises an expander, and step (v) further comprises cooling the CO2 stream to a first temperature by expanding the second compressed CO2 stream in the expander.

14. The method of claim 13, wherein the third cooling stage further comprises a fourth heat exchanger, and the method further comprises circulating a portion of the condensed CO2 stream to the fourth heat exchanger.

15. A system for condensing carbon dioxide (CO2) from a CO2 stream, comprising: (i) one or more compression stages configured to receive the CO2 stream;(ii) one or more cooling stages in fluid communication with the one or more compression stages, wherein a combination of the one or more compression 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;(iii) a magento-caloric cooling stage configured to receive the partially-cooled CO2 stream and cool the partially-cooled CO2 stream to a second temperature to form a cooled CO2 stream; and(iv) a condensation stage configured to condense a portion of CO2 in the cooled CO2 stream at the second temperature, thereby condensing CO2 from the cooled CO2 stream to form a condensed CO2 stream.

16. The system of claim 15, wherein the magneto-caloric cooling stage comprises a magneto-caloric cooling device and a heat exchanger, wherein the heat exchanger is in fluid communication with the one or more cooling stages and the one or more compression stages.

17. The system of claim 15, further comprising a pump configured to receive the condensed CO2 stream and increase the pressure of the condensed CO2 stream.

18. The system of claim 15, wherein the one or more cooling stages further comprises an expander.

19. The system of claim 15, wherein the one or more cooling stages comprises one or more heat exchangers configured to cool the CO2 stream using air, water, or combinations thereof.

20. The system of claim 15, further comprising a circulation loop configured to circulate a portion of the condensed CO2 stream to the one or more cooling stages.