Method and system for carbon dioxide capture

Abstract

The method comprises the following steps: (1) feeding raw material gas carrying an adsorbent into an adsorption tower, and adsorbing carbon dioxide in the raw material gas by using the adsorbent to obtain a first mixture containing decarburized gas and the adsorbent to be regenerated; (2) feeding the first mixture into a first magnetic separator, carrying out gas-solid separation on the input first mixture under the action of an external magnetic field, discharging decarburized gas, and outputting an adsorbent to be regenerated; (3) feeding the to-be-regenerated adsorbent of the regeneration gas into a regeneration tower, and purging the to-be-regenerated adsorbent by using the regeneration gas to desorb carbon dioxide in the to-be-regenerated adsorbent so as to obtain a second mixture containing the carbon dioxide and the regenerated adsorbent; and (4) feeding the second mixture into a second magnetic separator, carrying out gas-solid separation on the second mixture under the action of an external magnetic field, and outputting a carbon dioxide product gas and a regenerated adsorbent. The method and the system are favorable for improving the capture efficiency of the carbon dioxide.

Description

Technical Field

[0001] The present invention belongs to the field of carbon dioxide capture, and in particular relates to a method and a system for carbon dioxide capture. Background Art

[0002] At present, carbon emission reduction has received unprecedented attention. The current carbon dioxide capture technologies include solvent absorption technology, adsorption technology and gas membrane technology. Among them, solvent absorption technology is the only technology that can achieve industrial application of million tons of CO2 / year capture. However, due to the use of chemical agents such as organic amines, solvent absorption technology requires heating and regeneration, which has certain environmental risks and high energy consumption. Gas membrane technology is relatively immature and has not yet achieved the application of 10,000 tons of CO2 / year capture. Adsorption technology is based on the physical adsorption process of CO2 by adsorption materials, does not involve chemical reactions and chemical agent consumption, has low theoretical energy consumption, is environmentally friendly, and has good application prospects. At present, fixed bed adsorption technology has a small number of pilot or industrial demonstrations in the field of CO2 capture, but fixed bed adsorption technology requires the installation of more adsorption towers, and each tower is in different working states at the same time to achieve continuous operation of the overall system, which makes its equipment investment and floor space both high; fluidized bed adsorption technology can solve the problems of fixed bed technology in equipment investment and floor space, and is an efficient and intensive adsorption technology with great application prospects in the field of CO2 capture.

[0003] CN115069066A discloses an adsorption fluidized bed carbon capture system and method using low-pressure turbine steam from a power plant, which uses the low-pressure turbine steam from a power plant as a heat source to desorb and regenerate the adsorbent adsorbed with CO2 in a bubbling fluidized bed; the gas-solid separation device used in the disclosed fluidized bed device is a cyclone separator, which belongs to the traditional gas-solid separation method, and its separation effect is directly related to the size of the solid phase particles. The smaller the particle size, the worse the separation effect. The carbon capture system disclosed in this patent uses steam as a regeneration heat source, and the regenerated product CO2 gas contains a lot of water vapor, and it needs to undergo refining operations such as dehydration to obtain a CO2 product gas with a higher purity.

[0004] The current carbon dioxide capture technology has complex equipment and requires post-processing after carbon dioxide capture, which is a cumbersome process. Summary of the invention

[0005] The first object of the present invention is to provide a method for capturing carbon dioxide, which has a simple process and helps to improve the capture efficiency of carbon dioxide;

[0006] The second object of the present invention is to provide a system for capturing carbon dioxide used in the aforementioned method, which has a simple structure, is easy to use, and helps to improve the capture efficiency of carbon dioxide.

[0007] To achieve the first object of the present invention, the following technical solutions are adopted:

[0008] A method for carbon dioxide capture, comprising:

[0009] (1) delivering the raw gas carrying the adsorbent to an adsorption tower, and using the adsorbent to adsorb carbon dioxide in the raw gas to obtain a first mixture comprising decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide; and the adsorbent is a magnetic adsorbent;

[0010] (2) sending the first mixed material obtained in step (1) to a first magnetic separator, performing gas-solid separation on the input first mixed material under the action of an external magnetic field, discharging decarbonized gas, and outputting the adsorbent to be regenerated;

[0011] (3) delivering the regeneration gas carrying the adsorbent to be regenerated obtained in step (2) to a regeneration tower, and using the regeneration gas to purge the adsorbent to be regenerated obtained in step (2) to desorb carbon dioxide therein, thereby obtaining a second mixed material comprising carbon dioxide and the regenerated adsorbent; the temperature of the regeneration gas is 120-300° C.;

[0012] (4) The second mixed material obtained in step (3) is sent to a second magnetic separator, and the second mixed material is subjected to gas-solid separation under the action of an external magnetic field, and carbon dioxide product gas and regenerated adsorbent are output. The method for capturing carbon dioxide of the present invention preferably further comprises step (5), wherein the regenerated adsorbent from the second magnetic separator is sent to step (1) for use as an adsorbent.

[0013] In the method for capturing carbon dioxide of the present invention, preferably, the microstructure of the adsorbent contains micropores with a pore size of less than 2 nm, and preferably, the proportion of micropores in the adsorbent is not less than 60v%.

[0014] In the method for capturing carbon dioxide of the present invention, preferably, the specific surface area of ​​the adsorbent is not less than 500 m 2 / g.

[0015] In the method for capturing carbon dioxide of the present invention, preferably, the regeneration gas is carbon dioxide.

[0016] In the method for capturing carbon dioxide of the present invention, preferably, the adsorption tower (2) is a fluidized bed adsorption tower; and / or the regeneration tower (5) is a fluidized bed regeneration tower.

[0017] In the method for capturing carbon dioxide of the present invention, preferably, in step (2), the adsorption conditions include: the adsorption temperature is 0-40°C, and / or the residence time is 4-60min; and / or in step (4), the regeneration conditions include: the regeneration temperature is 120-300°C, and / or the residence time is 4-60min.

[0018] In the method for capturing carbon dioxide of the present invention, preferably, in step (2), the strength of the applied magnetic field of the first magnetic separator is 0.05-0.5 T; and / or

[0019] In step (4), the strength of the external magnetic field of the second magnetic separator is 0.05-0.5T.

[0020] In the method for capturing carbon dioxide of the present invention, preferably, in step (1), the raw gas is a gas containing carbon dioxide, preferably nitrogen or oxygen containing carbon dioxide.

[0021] In order to achieve the second object of the present invention, a system for capturing carbon dioxide used in the above method is also provided.

[0022] Preferably, the system comprises an adsorption unit and a desorption unit;

[0023] The adsorption unit comprises a first induced draft fan, an adsorption tower and a first magnetic separator which are sequentially connected through pipelines; wherein,

[0024] The inlet end of the first induced draft fan is provided with a raw gas feed pipeline, and the outlet end is provided with an adsorbent feed pipeline, which is used to introduce the raw gas into the adsorption tower and guide the adsorbent to the adsorption tower together with the raw gas; the adsorbent is a magnetic adsorbent;

[0025] The adsorption tower is used to use the input adsorbent to adsorb carbon dioxide in the input raw gas to obtain a first mixture containing decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide;

[0026] The first magnetic separator is provided with an external magnetic field, and is used to perform gas-solid separation on the input first mixed material under the action of the external magnetic field, discharge decarbonized gas, and output the adsorbent to be regenerated;

[0027] The desorption unit comprises a second induced draft fan, a regeneration tower and a second magnetic separator which are sequentially connected through pipelines; wherein,

[0028] The inlet end of the second induced draft fan is provided with a regeneration gas feed pipeline, and the outlet end is also connected to the solid outlet of the first magnetic separator, so as to introduce the regeneration gas into the regeneration tower, and introduce the adsorbent to be regenerated from the first magnetic separator to the regeneration tower together with the regeneration gas; the temperature of the regeneration gas is 120-300°C;

[0029] The regeneration tower is used to purge the input adsorbent to be regenerated by using the input regeneration gas to desorb carbon dioxide therein to obtain a second mixed material containing carbon dioxide and the regenerated adsorbent;

[0030] The second magnetic separator is provided with an external magnetic field, which is used to perform gas-solid separation on the input second mixed material under the action of the external magnetic field, and output carbon dioxide product gas and regenerated adsorbent.

[0031] In the system of the present invention, preferably, the inlet end of the adsorbent feed pipeline is connected to the solid outlet of the second magnetic separator, so as to send the regenerated adsorbent from the second magnetic separator to the adsorption unit for recycling.

[0032] The beneficial effects of the present invention are:

[0033] (1) The method and system for capturing carbon dioxide of the present invention can continuously separate high-purity CO2 product gas from the raw gas, thereby capturing CO2 from the raw gas and purifying the raw gas into decarbonized gas with a very low CO2 content for discharge. The magnetic separation process is efficient and environmentally friendly, thus solving the difficulty of separating gas and powdered adsorption materials in a gas-solid mixed system.

[0034] (2) The method and system for capturing carbon dioxide of the present invention adopts a magnetic separation device to separate the adsorbent after adsorption and the adsorbent after regeneration from the gas, thereby improving the gas-solid separation efficiency and enabling the use of solid powder adsorbents with smaller particle sizes, such as magnetic powder adsorbents, in the adsorption tower and the regeneration tower, thereby improving the adsorption characteristics of the adsorbent. When the particle size of the adsorbent material is reduced, it is beneficial to increase the gas-solid mass transfer contact area and improve the efficiency of the CO2 desorption and adsorption process. It is also beneficial to reduce the fluidization velocity required for solid fluidization, reduce the requirements for the gas flow rate to achieve the fluidization state, reduce the power of the capture system dynamic equipment, and reduce energy consumption. In the regeneration stage, CO2 product gas with a certain temperature is used as the regeneration gas source, thereby avoiding the problems of a decrease in the CO2 concentration of the product gas caused by water vapor sweeping and agglomeration of the adsorbent material in the presence of water to reduce the fluidization effect, thereby improving the efficiency of the regeneration process. The present invention comprehensively improves the efficiency of the carbon dioxide capture process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a process flow chart and a structural schematic diagram of the method and system for capturing carbon dioxide in one embodiment of the present invention. DETAILED DESCRIPTION

[0036] The technical solution and its effects of the present invention are further described below in conjunction with the accompanying drawings and specific implementations. The following implementations are only used to illustrate the content of the present invention, and the invention is not limited to the following implementations or examples. Simple changes made to the present invention using the concept of the present invention are all within the scope of the protection claimed by the present invention.

[0037] The present invention provides a method for capturing carbon dioxide, the method comprising:

[0038] (1) delivering the raw gas carrying the adsorbent to an adsorption tower, and using the adsorbent to adsorb carbon dioxide in the raw gas to obtain a first mixture comprising decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide; and the adsorbent is a magnetic adsorbent;

[0039] (2) sending the first mixed material obtained in step (1) to a first magnetic separator, performing gas-solid separation on the input first mixed material under the action of an external magnetic field, discharging decarbonized gas, and outputting the adsorbent to be regenerated;

[0040] (3) sending the regeneration gas carrying the adsorbent to be regenerated obtained in step (2) to a regeneration tower, and using the regeneration gas to purge the adsorbent to be regenerated obtained in step (2) to desorb carbon dioxide therein, thereby obtaining a second mixed material comprising carbon dioxide and the regenerated adsorbent; the temperature of the regeneration gas is 120-300° C., such as 140° C., 150° C., 160° C., 180° C., 200° C., 220° C., 240° C., 250° C., 260° C. and 280° C.;

[0041] (4) The second mixed material obtained in step (3) is sent to a second magnetic separator, and the gas-solid separation of the input second mixed material is performed under the action of an external magnetic field, and carbon dioxide product gas and regenerated adsorbent are output.

[0042] Those skilled in the art understand that the adsorbent, the adsorbent to be regenerated, and the regenerated adsorbent are transported through a solid transport device.

[0043] Those skilled in the art will appreciate that, in one embodiment, the adsorption tower is a fluidized bed adsorption tower; and / or the regeneration tower is a fluidized bed regeneration tower.

[0044] Those skilled in the art understand that decarbonized gas is the gas obtained by removing CO2 from the raw gas.

[0045] The present invention uses a magnetic adsorbent and a magnetic separation method to separate the adsorbent after adsorption and the adsorbent after regeneration from the gas, thereby improving the gas-solid separation efficiency, so that solid powder adsorbents with smaller particle sizes, such as magnetic powder adsorbents, can be used in the adsorption tower and the regeneration tower, thereby improving the adsorption characteristics of the adsorbent. After the particle size of the adsorbent material is reduced, it is beneficial to increase the gas-solid mass transfer contact area and improve the efficiency of the CO2 desorption and adsorption process. Secondly, it is beneficial to reduce the fluidization speed required for solid fluidization, reduce the requirements for gas flow rate to achieve the fluidization state, reduce the power of the capture system dynamic equipment, and reduce energy consumption. When the temperature of the regenerated gas is 120-300°C, the high temperature of the regenerated gas can be used to achieve the desorption of carbon dioxide on the adsorbent to be regenerated, thereby achieving the desorption of carbon dioxide and completing the regeneration of the adsorbent to be regenerated.

[0046] In one embodiment, in step (1), the raw gas is a gas containing carbon dioxide, preferably nitrogen or oxygen containing carbon dioxide.

[0047] In one embodiment, in step (1), the carbon dioxide content in the raw gas is 5-60v%, such as 10v%, 15v%, 20v%, 25v%, 30v%, 35v%, 40v%, 45v%, 50v% and 55v%.

[0048] In one embodiment, in step (1), the air volume of the raw gas is increased before the raw gas carries the adsorbent.

[0049] Those skilled in the art will appreciate that an induced draft fan may be used to increase the air volume.

[0050] In one embodiment, in step (1), the air volume of the raw gas after being lifted is assumed to be a CO2 mass flow rate calculated according to the CO2 concentration as L1 (L1 = volume flow rate * CO2 concentration * CO2 density), the mass flow rate of the adsorbent is L2, the ratio of L1 to L2 is a = L1 / L2, and the saturated adsorption capacity of the adsorbent for CO2 is V. It is preferred that the air volume of the raw gas is lifted to a / V = 20-95%, preferably 50-90%, such as 55%, 60%, 65%, 70%, 75%, 80%, 85% before carrying the adsorbent.

[0051] In one embodiment, in step (1), the saturated adsorption capacity of the adsorbent for CO2 is not less than 1.5%.

[0052] In one embodiment, in step (3), the regeneration gas is first increased in volume before carrying the adsorbent to be regenerated, preferably to a pressure not less than 30 kPaG, such as 31 kPaG, 32 kPaG, 33 kPaG, 34 kPaG, 35 kPaG and 40 kPaG.

[0053] In one embodiment, the method further comprises a step (5), wherein the regenerated adsorbent obtained in the step (3) is sent to the step (1) for use as an adsorbent, thereby realizing recycling of the adsorbent.

[0054] In one embodiment, the adsorbent has a particle size of 0.1-100 μm, such as 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm and 90 μm.

[0055] In one embodiment, the microstructure of the adsorbent contains micropores with a pore size of less than 2 nm, such as 1.5 nm, 1 nm and 0.5 nm; preferably, the proportion of micropores in the adsorbent is not less than 60v%, such as 61v%, 62v%, 63v%, 64v%, 65v%, 66v%, 67v%, 68v%, 69v%, 70v%, 80v% and 90v%.

[0056] Those skilled in the art understand that the proportion of micropores in the adsorbent refers to the volume ratio of micropores to all pores in the adsorbent.

[0057] In one embodiment, the specific surface area of ​​the adsorbent is not less than 500 m 2 / g, for example 510m 2 / g, 520m 2 / g, 530m 2 / g, 540m 2 / g, 550m 2 / g, 560m 2 / g, 570m 2 / g, 580m 2 / g, 590m 2 / g、600m 2 / g.

[0058] In one embodiment, the adsorbent includes activated carbon loaded or bonded with magnetic Fe3O4, wherein the mass percentage of magnetic Fe3O4 is 30-70%, such as 35%, 40%, 45%, 50%, 55%, 60% and 65%.

[0059] In one embodiment, the regeneration gas is carbon dioxide.

[0060] In the present invention, CO2 product gas with a certain temperature is used as the regeneration gas source in the regeneration step, which avoids the problems of CO2 concentration decrease in the product gas caused by water vapor sweep and agglomeration of adsorbent materials in water conditions that reduces the fluidization effect, thereby improving the efficiency of the regeneration process.

[0061] In one embodiment, in step (2), the adsorption conditions include: the adsorption temperature is 0-40°C, such as 5°C, 10°C, 15°C, 20°C, 25°C, 30°C and 35°C; and / or the residence time is 4-60min, such as 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min and 55min.

[0062] In one embodiment, in step (4), the regeneration conditions include: a regeneration temperature of 120-300°C, such as 140°C, 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, 260°C and 280°C; and / or a residence time of 4-60min, such as 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min and 55min.

[0063] In one embodiment, in step (2), the strength of the external magnetic field of the first magnetic separator is 0.05-0.5T, such as 0.1T, 0.15T, 0.2T, 0.25T, 0.3T, 0.35T, 0.4T and 0.45T.

[0064] In one embodiment, in step (4), the strength of the external magnetic field of the second magnetic separator is 0.05-0.5T, such as 0.1T, 0.15T, 0.2T, 0.25T, 0.3T, 0.35T, 0.4T and 0.45T.

[0065] The present invention also provides a system for capturing carbon dioxide used in the above method, such as Figure 1 As shown, the system includes an adsorption unit and a desorption unit;

[0066] The adsorption unit comprises a first induced draft fan 1, an adsorption tower 2 and a first magnetic separator 3 which are sequentially connected through pipelines; wherein:

[0067] The inlet end of the first induced draft fan 1 is provided with a raw gas feed pipeline 11, and the outlet end is provided with an adsorbent feed pipeline 12, which is used to introduce the raw gas into the adsorption tower 2 and guide the adsorbent to the adsorption tower 2 together with the raw gas; the adsorbent is a magnetic adsorbent;

[0068] The adsorption tower 2 is used to adsorb carbon dioxide in the input raw gas using the input adsorbent to obtain a first mixture containing decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide;

[0069] The first magnetic separator 3 is provided with an external magnetic field, which is used to perform gas-solid separation on the input first mixed material under the action of the external magnetic field, discharge the decarbonized gas, and output the adsorbent to be regenerated;

[0070] The desorption unit comprises a second induced draft fan 4, a regeneration tower and a second magnetic separator 6 which are sequentially connected through pipelines; wherein,

[0071] The inlet end of the second induced draft fan 4 is provided with a regeneration gas feed pipeline 41, and the outlet end is also connected to the solid outlet of the first magnetic separator 3, for introducing regeneration gas into the regeneration tower, and introducing the adsorbent to be regenerated from the first magnetic separator 3 to the regeneration tower together with the regeneration gas; the temperature of the regeneration gas is 120-300°C;

[0072] The regeneration tower is used to purge the input adsorbent to be regenerated by using the input regeneration gas to desorb carbon dioxide therein to obtain a second mixed material containing carbon dioxide and the regenerated adsorbent;

[0073] The second magnetic separator 6 is provided with an external magnetic field, and is used to perform gas-solid separation on the input second mixed material under the action of the external magnetic field, and output carbon dioxide product gas and regenerated adsorbent.

[0074] In one embodiment, the inlet end of the adsorbent feed pipeline 12 is connected to the solid outlet of the second magnetic separator 6 for sending the regenerated adsorbent from the second magnetic separator 6 to the adsorption unit for recycling.

[0075] Those skilled in the art understand that the adsorbent, the adsorbent to be regenerated, and the regenerated adsorbent are transported by a solid conveying device. For example, in one embodiment, the solid outlet of the first magnetic separator 3 is provided with a solid conveying device; in one embodiment, the solid outlet of the second magnetic separator (5) is provided with a solid conveying device; in one embodiment, the inlet of the adsorbent feed pipeline 12 is provided with a solid conveying device.

[0076] Use Figure 1 The process flow of carbon dioxide capture in the system shown is as follows Figure 1 As shown:

[0077] (1) The raw gas is sent to the first induced draft fan 1 through the raw gas feed pipeline 11 to increase the air volume, and the adsorbent is sent to the outlet pipeline of the first induced draft fan 1 through the adsorbent feed pipeline 12. The raw gas with increased air volume is sent to the adsorption tower 2 together with the adsorbent, and the adsorbent is used to adsorb carbon dioxide in the raw gas to obtain a first mixed material containing decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide; the adsorbent is a magnetic adsorbent;

[0078] (2) sending the first mixed material obtained in step (1) to a first magnetic separator 3, performing gas-solid separation on the input first mixed material under the action of an external magnetic field, discharging decarbonized gas, and outputting the adsorbent to be regenerated;

[0079] (3) The regenerated gas is sent to the second induced draft fan 4 through the regenerated gas feed pipeline 41 to increase the air volume, and the adsorbent to be regenerated obtained in step (2) is sent to the outlet pipeline of the second induced draft fan 4. The regenerated gas with increased air volume carries the adsorbent to be regenerated to the regeneration tower 5, and the adsorbent to be regenerated obtained in step (2) is purged by the regenerated gas to desorb carbon dioxide therein, thereby obtaining a second mixed material comprising carbon dioxide and the regenerated adsorbent;

[0080] (4) sending the second mixed material obtained in step (3) to a second magnetic separator 6, performing gas-solid separation on the input second mixed material under the action of an external magnetic field, and outputting carbon dioxide product gas and regenerated adsorbent;

[0081] (5) The regenerated adsorbent obtained in step (4) is sent to step (1) for use as an adsorbent.

[0082] The method and system for capturing carbon dioxide of the present invention can continuously separate high-purity CO2 product gas from the raw gas, thereby capturing CO2 from the raw gas and purifying the raw gas into decarbonized gas with a very low CO2 content for discharge. The magnetic separation process is efficient and environmentally friendly, thereby solving the difficulty of separating gas and powder adsorption materials in a gas-solid mixed system.

[0083] The present invention is further illustrated by the following specific examples.

[0084] Example 1 (S1)

[0085] According to Figure 1 The process flow and system of the method shown are used to capture carbon dioxide, as follows:

[0086] (1) Raw gas (volume flow rate is 1000Nm 3 / h) is sent to the first induced draft fan 1 through the raw gas feed pipeline 11 to increase the air volume, and the raw gas with increased air volume is sent to the adsorption tower 2 together with the adsorbent, and the adsorbent is used to adsorb carbon dioxide in the raw gas to obtain a first mixed material containing decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide; wherein,

[0087] The raw gas contains 15v% CO2, and the rest is nitrogen;

[0088] Assuming that the air volume of the raw gas after the lifting is calculated according to the CO2 concentration, the CO2 mass flow rate is L1=295kg / h, the mass flow rate of the adsorbent is L2=6000kg / h, the ratio of L1 to L2 is a=L1 / L2=4.9%, and the saturated adsorption capacity of the adsorbent for CO2 is V=6%, then the ratio of the CO2 mass flow rate in the raw gas to the adsorbent mass flow rate accounts for a / V=81.7% of the saturated adsorption capacity of the adsorbent;

[0089] The adsorbent is a magnetic adsorbent solid powder (the magnetic adsorbent solid powder is activated carbon loaded with magnetic Fe3O4, and the mass percentage of magnetic Fe3O4 is 50%), with a particle size of 1 μm and a specific surface area of ​​520 m 2 / g, its microstructure contains micropores with a pore size of less than 2nm, and the proportion of micropores in the adsorbent is 62v%;

[0090] The adsorption tower 2 is a fluidized bed adsorption tower, and the adsorption conditions include: adsorption temperature is 20°C and residence time is 15min;

[0091] (2) The first mixed material obtained in step (1) is sent to the first magnetic separator 3, where the first mixed material is subjected to gas-solid separation under the action of an external magnetic field, and decarbonized gas (flow rate is 847 Nm 3 / h, where the CO2 content is 1.5%), outputting the adsorbent to be regenerated; wherein,

[0092] The strength of the applied magnetic field of the first magnetic separator is 0.25T;

[0093] (3) The regenerated gas is sent to the second induced draft fan 4 through the regenerated gas feed pipeline 41 to increase the air volume to a pressure of 30 kPaG, and the adsorbent to be regenerated (mass flow rate of 6000 kg / h) obtained in step (2) is sent to the outlet pipeline of the second induced draft fan 4. The regenerated gas with increased air volume is sent to the regeneration tower 5 together with the adsorbent to be regenerated, and the adsorbent to be regenerated obtained in step (2) is purged with the regenerated gas to desorb carbon dioxide therein, thereby obtaining a second mixed material comprising carbon dioxide and the regenerated adsorbent; wherein:

[0094] The regeneration gas is heated CO2, and its flow rate is 400Nm 3 / h, CO2 concentration is 90%, temperature is 160℃;

[0095] The regeneration tower is a fluidized bed regeneration tower, and the regeneration conditions include: the regeneration temperature is 160°C, and the residence time is 10 minutes;

[0096] (4) The second mixed material obtained in step (3) is sent to the second magnetic separator 6, where the gas-solid separation of the input second mixed material is carried out under the action of an external magnetic field, and the carbon dioxide product gas (with a flow rate of 553 Nm3 / h, CO2 concentration is 90%) and regenerated adsorbent; the net value of carbon dioxide product gas obtained in this process is 153Nm 3 / h, purity is 90%; among which,

[0097] The strength of the applied magnetic field of the second magnetic separator is 0.25T;

[0098] (5) The regenerated adsorbent obtained in step (4) is sent to step (1) for recycling as adsorbent.

[0099] result:

[0100] In step (2), the flow rate of the discharged decarbonized gas is 847 Nm 3 / h, of which the content of CO2 is 1.5%;

[0101] In step (4), the flow rate of the output carbon dioxide product gas is 553Nm 3 / h, and the CO2 content is 90%; the net value of the carbon dioxide product gas obtained in this process is 153Nm 3 / h, purity is 90%;

[0102] By cyclically operating steps (1) to (5) in Example 1, it is possible to continuously separate high-purity CO2 product gas from the raw gas, and at the same time, the raw gas is purified to be discharged as decarbonized gas with a very low CO2 content; the overall system has a CO2 capture rate of 91.5% in the raw gas, and the purity of the obtained CO2 product gas is 90%.

[0103] Embodiment 2 (S2)

[0104] Carbon dioxide is captured according to the method and system of Example 1 (S1), which differs from Example 1 (S1) only in the following ways:

[0105] In step (1), the volume flow rate of the raw gas is 1000 Nm 3 / h; the raw gas contains 5v% CO2, the rest is nitrogen;

[0106] L1 = 98 kg / h, L2 = 6125 kg / h, a = 1.6%, the saturated adsorption capacity of the adsorbent for CO2 is V = 8%, then the ratio of the mass flow rate of CO2 in the feed gas to the mass flow rate of the adsorbent accounts for a / V = 20% of the saturated adsorption capacity of the adsorbent;

[0107] The particle size of the adsorbent is 0.5 μm and the specific surface area is 700 m 2 / g, its microstructure contains micropores with a pore size of less than 2nm, and the proportion of micropores in the adsorbent is 70v%;

[0108] The adsorption conditions of the adsorption tower 2 include: adsorption temperature of 0°C and residence time of 60min;

[0109] In step (2), the strength of the external magnetic field of the first magnetic separator is 0.35 T;

[0110] In step (3), the regenerated gas is sent to the second induced draft fan 4 through the regenerated gas feed pipeline 41 to increase the air volume to a pressure of 35 kPaG; the adsorbent to be regenerated obtained in step (2) has a mass flow rate of 6125 kg / h;

[0111] The regeneration gas is heated CO2, and its flow rate is 400Nm 3 / h, CO2 concentration is 90%, temperature is 120℃;

[0112] The regeneration tower is a fluidized bed regeneration tower, and the regeneration conditions include: the regeneration temperature is 120°C, and the residence time is 60min;

[0113] In step (4), the strength of the external magnetic field of the second magnetic separator is 0.25 T;

[0114] (5) The regenerated adsorbent obtained in step (4) is sent to step (1) for recycling as adsorbent.

[0115] result:

[0116] In step (2), the flow rate of the discharged decarbonized gas is 950 Nm 3 / h, of which the content of CO2 is 0.5%;

[0117] In step (4), the flow rate of the output carbon dioxide product gas is 450Nm 3 / h, and the CO2 content is 90%; the net value of the carbon dioxide product gas obtained in this process is 50Nm 3 / h, purity is 90%;

[0118] By cyclically operating steps (1) to (5) in Example 2, it is possible to continuously separate high-purity CO2 product gas from the raw gas, and at the same time, the raw gas is purified to be discharged as decarbonized gas with a very low CO2 content; the overall system has a CO2 capture rate of 90.5% in the raw gas, and the purity of the obtained CO2 product gas is 90%.

[0119] Embodiment 3 (S3)

[0120] Carbon dioxide is captured according to the method and system of Example 1 (S1), which differs from Example 1 (S1) only in the following ways:

[0121] In step (1), the volume flow rate of the raw gas is 1000 Nm 3 / h; the raw gas contains 60v% CO2 and the rest is oxygen;

[0122] L1 = 1180 kg / h, L2 = 12421 kg / h, a = 9.5%, the saturated adsorption capacity of the adsorbent for CO2 is V = 10%, then the ratio of the mass flow rate of CO2 in the feed gas to the mass flow rate of the adsorbent accounts for a / V = 95% of the saturated adsorption capacity of the adsorbent;

[0123] The particle size of the adsorbent is 2 μm and the specific surface area is 800 m 2 / g, its microstructure contains micropores with a pore size of less than 2nm, and the proportion of micropores in the adsorbent is 75v%;

[0124] The adsorption conditions of the adsorption tower 2 include: adsorption temperature of 40°C and residence time of 4 minutes;

[0125] In step (2), the strength of the external magnetic field of the first magnetic separator is 0.1 T;

[0126] In step (3), the regenerated gas is sent to the second induced draft fan 4 through the regenerated gas feed pipeline 41 to increase the air volume to a pressure of 40 kPaG; the adsorbent to be regenerated obtained in step (2) has a mass flow rate of 12421 kg / h;

[0127] The regeneration gas is heated CO2, and its flow rate is 1200Nm 3 / h, CO2 concentration is 95%, temperature is 120℃;

[0128] The regeneration tower is a fluidized bed regeneration tower, and the regeneration conditions include: the regeneration temperature is 300°C, and the residence time is 4 minutes;

[0129] In step (4), the strength of the external magnetic field of the second magnetic separator is 0.1 T;

[0130] (5) The regenerated adsorbent obtained in step (4) is sent to step (1) for recycling as adsorbent.

[0131] result:

[0132] In step (2), the flow rate of the discharged decarbonized gas is 412 Nm 3 / h, where the content of CO2 is 10%;

[0133] In step (4), the flow rate of the output carbon dioxide product gas is 1288Nm 3 / h, and the CO2 content is 95%; the net value of the carbon dioxide product gas obtained in this process is 588Nm 3 / h, purity is 95%;

[0134] By cyclically operating steps (1) to (5) in Example 3, it is possible to continuously separate high-purity CO2 product gas from the raw gas, and at the same time, the raw gas is purified to be discharged as decarbonized gas with a very low CO2 content; the overall system has a CO2 capture rate of 93.1% in the raw gas, and the purity of the obtained CO2 product gas is 95%.

[0135] Embodiment 4 (S4)

[0136] Carbon dioxide is captured according to the method and system of Example 1 (S1), which differs from Example 1 (S1) only in the following ways:

[0137] In step (1), a=3%, the saturated adsorption capacity of the adsorbent for CO2 is V=6%, then the ratio of the mass flow rate of CO2 in the feed gas to the mass flow rate of the adsorbent is a / V=50% of the saturated adsorption capacity of the adsorbent.

[0138] result:

[0139] In step (2), the flow rate of the discharged decarbonized gas is 833 Nm 3 / h, where the content of CO2 is 1%;

[0140] In step (4), the flow rate of the output carbon dioxide product gas is 567Nm 3 / h, and the CO2 content is 88.5%; the net value of the carbon dioxide product gas obtained in this process is 167Nm 3 / h, purity is 85%;

[0141] By cyclically operating steps (1) to (5) in Example 4, it is possible to continuously separate high-purity CO2 product gas from the raw gas, and at the same time, the raw gas is purified to be discharged as decarbonized gas with a very low CO2 content; the overall system has a CO2 capture rate of 94% in the raw gas, and the purity of the obtained CO2 product gas is 85%.

[0142] Embodiment 5 (S5)

[0143] Carbon dioxide is captured according to the method and system of Example 1 (S1), which differs from Example 1 (S1) only in the following ways:

[0144] In step (1), a=5.4%, the saturated adsorption capacity of the adsorbent for CO2 is V=6%, and the ratio of the mass flow rate of CO2 in the feed gas to the mass flow rate of the adsorbent is a / V=90% of the saturated adsorption capacity of the adsorbent.

[0145] result:

[0146] In step (2), the flow rate of the discharged decarbonized gas is 862Nm 3 / h, of which the CO2 content is 2.5%;

[0147] In step (4), the flow rate of the output carbon dioxide product gas is 538Nm 3 / h, and the CO2 content is 90.8%; the net value of the carbon dioxide product gas obtained in this process is 138Nm 3 / h, purity is 93%;

[0148] By cyclically operating steps (1) to (5) in Example 5, it is possible to continuously separate high-purity CO2 product gas from the raw gas, and at the same time, the raw gas is purified to be discharged as decarbonized gas with a very low CO2 content; the overall system has a CO2 capture rate of 85.6% in the raw gas, and the purity of the obtained CO2 product gas is 93%.

[0149] According to Examples 1-5, the method and system for capturing carbon dioxide of the present invention can continuously separate high-purity CO2 product gas from the raw gas, thereby capturing CO2 from the raw gas, while purifying the raw gas into decarbonized gas with a very low CO2 content for discharge. The magnetic separation process is efficient and environmentally friendly, thereby solving the problem of separation of gas and powder adsorption materials in a gas-solid mixed system.

Claims

1. A method for capturing carbon dioxide, characterized in that: The method comprises: (1) delivering the raw gas carrying the adsorbent to an adsorption tower, and using the adsorbent to adsorb carbon dioxide in the raw gas to obtain a first mixture comprising decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide; and the adsorbent is a magnetic adsorbent; (2) sending the first mixed material obtained in step (1) to a first magnetic separator, performing gas-solid separation on the input first mixed material under the action of an external magnetic field, discharging decarbonized gas, and outputting the adsorbent to be regenerated; (3) delivering the regeneration gas carrying the adsorbent to be regenerated obtained in step (2) to a regeneration tower, and using the regeneration gas to purge the adsorbent to be regenerated obtained in step (2) to desorb carbon dioxide therein, thereby obtaining a second mixed material comprising carbon dioxide and the regenerated adsorbent; the temperature of the regeneration gas is 120-300° C.; (4) The second mixed material obtained in step (3) is sent to a second magnetic separator, and the gas-solid separation of the input second mixed material is performed under the action of an external magnetic field, and carbon dioxide product gas and regenerated adsorbent are output.

2. The method according to claim 1, characterized in that The method further comprises a step (5) of sending the regenerated adsorbent from the second magnetic separator to the step (1) for use as an adsorbent.

3. The method according to claim 1 or 2, characterized in that: The microstructure of the adsorbent contains micropores with a pore size of less than 2 nm, and preferably the proportion of micropores in the adsorbent is not less than 60v%; and / or The specific surface area of ​​the adsorbent is not less than 500m 2 / g.

4. The method according to any one of claims 1 to 3, characterized in that The regeneration gas is carbon dioxide.

5. The method according to any one of claims 1 to 4, characterized in that The adsorption tower (2) is a fluidized bed adsorption tower; and / or The regeneration tower (5) is a fluidized bed regeneration tower.

6. The method according to any one of claims 1 to 5, characterized in that In step (2), the adsorption conditions include: adsorption temperature of 0-40°C, and / or residence time of 4-60 min; and / or In step (4), the regeneration conditions include: a regeneration temperature of 120-300° C., and / or a residence time of 4-60 min.

7. The method according to any one of claims 1 to 6, characterized in that In step (2), the strength of the applied magnetic field of the first magnetic separator is 0.05-0.5T; and / or In step (4), the strength of the external magnetic field of the second magnetic separator is 0.05-0.5T.

8. The method according to any one of claims 1 to 7, characterized in that In step (1), the raw gas is a gas containing carbon dioxide, preferably nitrogen or oxygen containing carbon dioxide.

9. A system for capturing carbon dioxide used in the method according to any one of claims 1 to 8, characterized in that: The system includes an adsorption unit and a desorption unit; The adsorption unit comprises a first induced draft fan (1), an adsorption tower (2) and a first magnetic separator (3) which are sequentially connected via pipelines; wherein: The inlet end of the first induced draft fan (1) is provided with a raw gas feed pipeline (11), and the outlet end is provided with an adsorbent feed pipeline (12), which is used to introduce the raw gas into the adsorption tower (2) and to guide the adsorbent to the adsorption tower (2) together with the raw gas; the adsorbent is a magnetic adsorbent; The adsorption tower (2) is used to use the input adsorbent to adsorb carbon dioxide in the input raw gas to obtain a first mixed material containing decarbonized gas and the adsorbent to be regenerated; the adsorbent to be regenerated is an adsorbent adsorbing carbon dioxide; The first magnetic separator (3) is provided with an external magnetic field, and is used to perform gas-solid separation on the input first mixed material under the action of the external magnetic field, discharge decarbonized gas, and output adsorbent to be regenerated; The desorption unit comprises a second induced draft fan (4), a regeneration tower (5) and a second magnetic separator (6) which are sequentially connected via pipelines; wherein: The inlet end of the second induced draft fan (4) is provided with a regeneration gas feed pipeline (41), and the outlet end is also connected to the solid outlet of the first magnetic separator (3), so as to introduce the regeneration gas into the regeneration tower (5), and introduce the adsorbent to be regenerated from the first magnetic separator (3) to the regeneration tower (5) together with the regeneration gas; the temperature of the regeneration gas is 120-300°C; The regeneration tower (5) is used to use the input regeneration gas to purge the input adsorbent to be regenerated, so as to desorb the carbon dioxide therein, and obtain a second mixed material containing carbon dioxide and the regenerated adsorbent; The second magnetic separator (6) is provided with an external magnetic field, and is used to perform gas-solid separation on the input second mixed material under the action of the external magnetic field, and output carbon dioxide product gas and regenerated adsorbent.

10. The system according to claim 9, characterized in that: The inlet end of the adsorbent feed pipeline (12) is connected to the solid outlet of the second magnetic separator (6) for sending the regenerated adsorbent from the second magnetic separator (6) to the adsorption unit for recycling.

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