A device and method for capturing carbon dioxide in MTO regenerated flue gas

Abstract

The application discloses a device for capturing carbon dioxide in MTO regenerated flue gas, which comprises a heat exchange zone, a dust removal and decarburization zone and a dust collection zone arranged in a shell from top to bottom; the upper part of the heat exchange zone is provided with a flue gas inlet, and the lower part is provided with a flue gas communication pipe which is communicated with the dust removal and decarburization zone; the dust removal and decarburization zone is divided into a rough gas zone and a clean gas zone; the lower part of the rough gas zone is an air inlet chamber, the upper part of the air inlet chamber is provided with a gas redistributor, the gas redistributor is provided with a gas redistribution port, and the upper part of the gas redistributor is provided with a ceramic membrane tube; a venturi tube is arranged in the clean gas zone, and the ceramic membrane tube is distributed below the venturi tube; the dust collection zone is provided with a dust hopper, a dust discharge valve and a dust discharge port, and the dust hopper is arranged below the air inlet chamber. The device can realize the dual effects of dust removal and decarburization, has simple process, compact arrangement and small floor space.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon capture, and in particular relates to a device and method for capturing carbon dioxide in MTO regeneration flue gas. Background Art

[0002] In recent years, global fossil fuel combustion has emitted tens of billions of tons of carbon dioxide annually, triggering a greenhouse effect that is increasingly impacting the human environment. With increasingly stringent environmental regulations and growing public awareness of environmental protection, the greenhouse effect caused by excessive carbon emissions has garnered widespread attention from society, making controlling and reducing atmospheric carbon dioxide levels a pressing global issue.

[0003] Carbon dioxide capture, utilization, and storage (CCUS) is an effective way to reduce carbon dioxide emissions and achieve economical and reliable recovery and comprehensive utilization of carbon dioxide. Carrying out relevant technology research and development is an important strategic choice for my country to meet the dual carbon goals. Carbon dioxide capture technology is the key to achieving CCUS and is also one of the important factors currently limiting the widespread application of CCUS. Traditional technologies mainly include pre-combustion capture, eutrophic combustion, and post-combustion capture. Post-combustion capture can be divided into physical adsorption, membrane separation, cryogenic distillation, and chemical absorption. The chemical absorption method utilizes the reversible reaction between the absorbent and carbon dioxide, that is, the absorbent absorbs carbon dioxide at a relatively low temperature (about 40°C), and the reaction product desorbs carbon dioxide at a high temperature (about 120°C). Organic amine aqueous solution is a commonly used chemical absorbent (Sun Luchang, Wang Zhengrong, Wu Chong, et al. Research on the design and operation optimization of a 10,000-ton carbon capture project in a coal-fired power plant [J]. Huadian Technology, 2021, 43(6):10). In recent years, most large-scale flue gas CO2 capture projects launched at home and abroad are based on chemical absorption technology. However, due to the large flue gas flow rate, low CO2 partial pressure, complex composition, including nitrogen oxides, sulfur oxides, dust, etc., the technology currently has high equipment investment costs, high operating energy consumption and serious solvent degradation, which greatly limits the promotion of this technology (Chen Jian, Luo Weiliang, Li Han. Research progress on thermodynamics and kinetics of organic amine absorption of CO2 [J]. Journal of Chemical Industry and Engineering, 2014, 65(1):10).

[0004] Methanol to olefins (MTO) is an important way to produce low-carbon olefins from non-petroleum resources and to utilize coal in a clean and efficient manner. However, modern coal chemical industry is an industry with high energy consumption, high water consumption and high emissions. Currently, energy conservation and carbon reduction are under great pressure. Due to the characteristics of easy deactivation of MTO reaction catalysts, in order to ensure the activity and selectivity of the catalyst, the deactivated catalyst needs to be sent to the regenerator for carbonization regeneration to restore the catalytic activity. The carbonization regeneration of MTO catalysts is mainly carried out by oxidizing and removing the carbon deposits on the molecular sieve at high temperatures (up to 660°C) with air or oxygen. This method not only increases carbon dioxide emissions, but also produces a large number of fine particulate matter that is difficult to separate (about 200mg / m 3 Particulate matter enters the subsequent waste heat boiler section along with the flue gas from the MTO regeneration unit, causing erosion and wear, leading to thinning of the lower connecting pipe wall, which could seriously endanger boiler operation. Furthermore, due to the high temperature and dust content of the flue gas from the MTO regeneration unit, the currently more mature chemical absorption method for carbon capture is economically and technically unsuitable.

[0005] Patent CN202110740127.7 discloses an energy-saving process for capturing and recovering carbon dioxide from chimney exhaust. This process involves scrubbing and cooling high-temperature flue gas to 40°C-50°C before chemically capturing the carbon. During the CO2 capture and recovery process, multi-stage heat recovery and reuse are used to reduce energy consumption. However, the use of water spray to cool the high-temperature flue gas results in significant energy waste.

[0006] Patent ZL202110884249.3 reports a process for the complete recovery of carbon dioxide emitted from a catalytic cracking regeneration unit. This process circulates the flue gas from the catalytic cracking regeneration unit, enriching the carbon dioxide and making it easier to capture carbon dioxide. In addition, the process uses a carbon-based gas prepared by mixing the recycled flue gas and oxygen as a combustion-supporting gas, and carbon dioxide replaces nitrogen as a protective gas, avoiding the formation of nitrogen oxides during the combustion process and greatly reducing the cost of denitrification. However, the process is complex and cumbersome, with high control requirements, and the oxygen introduction system poses a major safety hazard, so its scalability is not high.

[0007] In summary, achieving near-zero emissions from MTO regeneration units requires the support of high-temperature CO2 capture technology, and a solution remains unproven. Given the high temperature and dust content of MTO regeneration unit flue gas, finding a multifunctional, synergistic system that can both remove dust from MTO regeneration unit flue gas and efficiently capture CO2 could potentially form an integrated technology for efficient dust removal and decarbonization of MTO regeneration unit flue gas. Summary of the Invention

[0008] Purpose of the invention: The purpose of the present invention is to address the deficiencies of the prior art and provide a device for capturing carbon dioxide in MTO regeneration flue gas that can simultaneously remove dust and carbon.

[0009] Another object of the present invention is to provide a method for capturing carbon dioxide in MTO regeneration flue gas with simultaneous dust and carbon removal.

[0010] Technical solution: The device for capturing carbon dioxide in MTO regeneration flue gas of the present invention comprises a heat exchange zone, a dust removal and decarbonization zone, and a dust collection zone which are sequentially arranged in a shell from top to bottom;

[0011] The upper part of the heat exchange zone is provided with an air inlet for regeneration flue gas, and the lower part is provided with a connecting pipe for regeneration flue gas connected to the dust removal and decarbonization zone. The regeneration flue gas flows into the dust removal and decarbonization zone after cooling down in the heat exchange zone.

[0012] The dust removal and decarbonization zone is divided into two parts, the lower part is the coarse air zone, and the upper part is the clean air zone. The lower part of the coarse air zone is an air inlet chamber connected to the connecting pipe, and a gas redistributor is provided above the air inlet chamber. The gas redistributor is provided with a gas redistribution port, and a ceramic membrane tube is provided above the gas redistributor; a Venturi tube is provided in the clean air zone, and the ceramic membrane tubes are multiple tubes distributed below the Venturi tube; after entering the air inlet chamber, the regenerated flue gas enters the ceramic membrane tube distribution area through the gas redistribution port for dust removal and decarbonization, and finally enters the Venturi tube of the clean air zone through the ceramic membrane tube; a regenerated flue gas outlet is provided at the upper part of the clean air zone, and the treated regenerated flue gas is discharged from the regenerated flue gas outlet;

[0013] The dust collecting area is provided with an ash collecting hopper, an ash discharging valve and an ash discharging port. The ash collecting hopper is arranged below the air inlet chamber. The dust falling from the dust removal and decarbonization area enters the ash collecting hopper and is discharged through the ash discharging valve and the ash discharging port.

[0014] In order to recycle the device, the device of the present invention also includes a back-blowing system, which includes a blowing gas inlet pipe, a pulse valve, a blowing pipe and a blowing head connected in sequence. The blowing pipe enters from the clean air zone, and the blowing head is arranged in the Venturi tube.

[0015] Furthermore, the device of the present invention also includes a regeneration system, which includes a regeneration gas inlet and a regeneration gas outlet. The regeneration gas inlet is arranged at the bottom of the air inlet chamber, and the regeneration gas outlet is arranged at the upper part of the clean air zone.

[0016] Preferably, the heat exchange zone is provided with a heat exchange coil and a baffle, and heat exchange is performed through cooling water.

[0017] In order to reduce the heat loss of MTO regeneration flue gas, the outer wall of the shell is provided with an insulation layer, which can be made of common thermal insulation materials on the market, preferably a composite silicate insulation material layer with a thickness of 50 to 300 mm.

[0018] In order to protect the dust removal and decarbonization zone from being damaged by high temperature and to extend the service life of the device, the inner wall of the dust removal and decarbonization zone is built with refractory bricks.

[0019] The ceramic membrane tube of the present invention has a diameter of 100 to 300 mm, an operating temperature between 200 and 650°C, a dust removal efficiency of over 99.98%, and a carbon dioxide capture rate of over 85%. The ceramic membrane tube of the present invention uses a dust removal membrane as a carrier, utilizing the dust removal membrane's efficient dust filtration performance and the load-bearing capacity of its highly porous structure. By loading a high-efficiency carbon dioxide adsorbent within the ceramic dust removal membrane material, a ceramic membrane tube with dust removal and decarbonization functions is produced.

[0020] The ceramic membrane tube of the present invention is prepared according to the following steps:

[0021] a) Place the mullite, cordierite, corundum, silicon oxide or silicon carbide ceramic dust removal membrane tube in a 20% to 60% citric acid, oxalic acid or hydrochloric acid solution and heat it in a microwave or water bath at 45 to 100°C for 0.4 to 6 hours, then clean it with ultrasonic waves and dry it;

[0022] b) Calcium ferrite, an active component for carbon dioxide adsorption, is loaded into the pores of the ceramic dust removal membrane tube treated in a) above by a pressure impregnation method or a vacuum impregnation method, and then dried and calcined at 800-1400° C. for 1-6 hours to obtain a ceramic membrane tube.

[0023] The preparation method of the carbon dioxide adsorption active component calcium ferrite is as follows: ferric nitrate, calcium nitrate, C4H6O5 (malic acid) or C4H6O6 (tartaric acid) are dissolved in water and ethanol to form a solution, and then the pH value of the solution is adjusted to 7-9 with sodium hydroxide, ammonia water or ethylenediamine to obtain a calcium ferrite solution. The molar ratio of the raw materials in the solution is Fe: Ca: C4H6O5 / C4H6O6=1:(1.5-1):(2-6).

[0024] The method for capturing carbon dioxide from MTO regeneration flue gas using the device of the present invention comprises the following steps:

[0025] S1. Input the MTO regeneration flue gas with a temperature of 550-700℃ into the heat exchange zone for heat exchange, and the temperature drops to 350-450℃ after heat exchange;

[0026] S2. The MTO regeneration flue gas from the heat exchange area is transported to the air inlet chamber of the dust removal and decarbonization area. After being rectified by the gas redistributor, it enters the ceramic membrane tube distribution area through the gas redistribution port. The dust and carbon dioxide in the MTO regeneration flue gas are captured and processed by the inner and outer surfaces of the ceramic membrane tube. The treated gas is discharged from the outlet of the clean gas area through the Venturi tube into the subsequent section.

[0027] After the ceramic membrane tube is saturated with carbon dioxide, the ceramic membrane tube is regenerated. The steps for regenerating the ceramic membrane tube include:

[0028] S3. Use room temperature air or nitrogen as backflush gas, which enters the Venturi tube from the injection gas inlet pipe to backflush and clean the ceramic membrane tube arranged below the Venturi tube, and blow the dust accumulated on the surface of the ceramic membrane tube into the dust collecting hopper in the dust collecting area;

[0029] S4. Use carbon dioxide or nitrogen with a temperature of 550-650℃ as the regeneration gas, which enters from the regeneration gas inlet. Utilizing the principle of high-temperature desorption of carbon dioxide, the high-temperature regeneration gas passes through the ceramic membrane tube to desorb carbon dioxide and achieve ceramic membrane tube regeneration; the regeneration gas with desorbed carbon dioxide is discharged from the regeneration gas outlet and enters the subsequent process section.

[0030] Beneficial effects: (1) The preparation device of the present invention is suitable for capturing and separating carbon dioxide from high-temperature flue gas (MTO regeneration flue gas) of a methanol to olefin (MTO) regeneration device. By utilizing the dust removal and decarbonization characteristics of a specially made ceramic membrane tube, carbon dioxide in the MTO regeneration flue gas can be captured, thereby reducing carbon dioxide emissions; and dust removal is performed simultaneously, which has a dual effect. (2) The device of the present invention removes dust from high-temperature flue gas, thereby preventing erosion and wear of subsequent equipment by dust in the gas, thereby saving subsequent equipment maintenance costs. (3) The device of the present invention has a compact layout and a small footprint, which solves a series of problems in the traditional process, such as a long process flow, a large equipment footprint, and poisoning and abrasion of decarbonization adsorbents caused by factors such as dust and alkali metals, which are caused by separate steps of dust removal and decarbonization. It can maximize the service life of the ceramic membrane tube and reduce the decarbonization cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the overall structure of the device of the present invention.

[0032] Figure 2 for Figure 1 Cross-sectional view in the AA direction.

[0033] Figure 3 for Figure 1 Cross-sectional view in the BB direction.

[0034] In the figure: 1. Shell; 2. Heat exchange zone; 3. Dust removal and decarbonization zone; 4. Dust collection zone; 5. Regeneration flue gas inlet; 6. Regeneration flue gas outlet; 7. Connecting pipe; 8. Regeneration gas inlet; 9. Regeneration gas outlet; 10. Backflush system; 11. Cooling water inlet; 12. Cooling water outlet; 21. Heat exchange coil; 22. Baffle; 31. Raw gas zone; 32. Clean gas zone; 33. Venturi tube; 34. Ceramic membrane tube; 35. Gas redistributor; 36. Air inlet chamber; 41. Ash hopper; 42. Ash discharge valve; 43. Ash discharge port; 101. Blowing gas inlet pipe; 102. Pulse valve; 103. Blowing pipe; 104. Blowing head; 361. Gas redistribution port. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the embodiments.

[0036] Example 1: A device for capturing carbon dioxide in MTO regeneration flue gas comprises a heat exchange zone 2, a dust removal and decarbonization zone 3 and a dust collection zone 4 arranged in sequence from top to bottom in a shell 1; the outer wall of the shell is provided with a composite silicate insulation layer with a thickness of 150 mm.

[0037] The heat exchange zone 2 is provided with a heat exchange coil 21 and a baffle 22, and cooling water flows in from the cooling water inlet 11 and flows out from the cooling water outlet 12; the upper part of the heat exchange zone 2 is provided with an air inlet 5 for regenerated flue gas, and the lower part is provided with a connecting pipe 7 for regenerated flue gas connected to the dust removal and decarbonization zone 3. The regenerated flue gas flows into the dust removal and decarbonization zone 3 after being cooled by the heat exchange zone 2.

[0038] The dust removal and decarbonization zone 3 is divided into two parts, the lower part is the coarse air zone 31, and the upper part is the clean air zone 32. The lower part of the coarse air zone 31 is an air inlet chamber 36 connected to the connecting pipe 7. A gas redistributor 35 is provided above the air inlet chamber 36. The gas redistributor 35 is provided with a gas redistribution port 361. A ceramic membrane tube 34 is provided above the gas redistributor 35; a Venturi tube 33 is provided in the clean air zone 32, and the ceramic membrane tube 34 is distributed as multiple tubes below the Venturi tube 33; the regenerated flue gas enters the air inlet chamber 36, is rectified by the gas redistributor 35, and enters the distribution area of ​​the ceramic membrane tube 34 through the gas redistribution port 361 for dust removal and decarbonization, and finally enters the Venturi tube 33 of the clean air zone through the ceramic membrane tube 34; a regenerated flue gas outlet 6 is provided at the upper part of the clean air zone 32, and the treated regenerated flue gas is discharged from the regenerated flue gas outlet 6. The inner wall of the dust removal and decarbonization zone 3 is built with refractory bricks.

[0039] The dust collecting area 4 is provided with an ash collecting hopper 41, an ash discharging valve 42 and an ash discharging port 43. The ash collecting hopper 41 is arranged below the air inlet chamber 36. The dust falling from the dust removal and decarbonization area 3 enters the ash collecting hopper 41 and is discharged through the ash discharging valve 42 and the ash discharging port 43.

[0040] The back-blowing system 10 is arranged in the clean air zone, and the back-blowing system 10 includes a blowing gas inlet pipe 101, a pulse valve 102, a blowing pipe 103 and a blowing head 104 connected in sequence. The blowing pipe 103 enters from the clean air zone 32, and the blowing head 104 is arranged in the Venturi tube 33.

[0041] The regeneration system includes a regeneration gas inlet 8 and a regeneration gas outlet 9 . The regeneration gas inlet is arranged at the bottom of the air inlet chamber 36 , and the regeneration gas outlet 9 is arranged at the upper part of the clean gas zone 32 .

[0042] The ceramic membrane tube 34 is prepared according to the following steps:

[0043] a) The cordierite ceramic dust removal membrane tube was placed in a 45% citric acid solution and microwave-heated at 90°C for 3 h, then ultrasonically cleaned and dried;

[0044] b) by pressure impregnation method of the carbon dioxide adsorption active component calcium ferrite loaded on the above a) in the dust removal membrane tube treated ceramic dust removal membrane pores, and then dried, calcined at 1300 ℃ 2h to obtain a ceramic membrane tube 34;

[0045] The preparation method of the active component calcium ferrite is as follows: using ferric nitrate (Fe(NO3)3·9H2O) as an iron source and calcium nitrate (Ca(NO3)2·4H2O) as a calcium source, dissolving ferric nitrate, calcium nitrate, and C4H6O5 (malic acid) in water and ethanol to form a solution, and then adjusting the pH value of the solution to 7.5 with sodium hydroxide, ammonia water, or ethylenediamine to obtain a calcium ferrite solution. The molar ratio of the raw materials in the solution is Fe: Ca: C4H6O5=1:1:4.

[0046] Example 2: A method for capturing carbon dioxide from MTO regeneration flue gas using the device of Example 1 comprises the following steps:

[0047] S1, heat exchange: the MTO regeneration flue gas with a temperature of about 650℃ (dust content 200mg / Nm 3 , carbon dioxide content 13.8%) is input into the heat exchange zone for heat exchange, and the temperature drops to about 400℃ after heat exchange;

[0048] S2. Decarbonization and dust removal: The MTO regeneration flue gas from the heat exchange area is transported to the air inlet chamber of the dust removal and decarbonization area, and enters the ceramic membrane tube distribution area after being rectified by the gas redistributor. The dust and carbon dioxide in the MTO regeneration flue gas are captured and processed by the inner and outer surfaces of the ceramic membrane tube. The treated gas (dust content is about 5mg / Nm 3 , carbon dioxide content 2.4%) is discharged from the outlet of the clean gas zone through the Venturi tube into the subsequent process section;

[0049] S3. Dust cleaning: Using room temperature air as back-blowing gas, it enters the venturi tube from the injection gas inlet pipe, and back-blows the ceramic membrane tube arranged below the venturi tube to clean the dust accumulated on the surface of the ceramic membrane tube into the dust collecting hopper in the dust collecting area. The dust is then discharged out of the device through the ash discharge valve 42 and the ash discharge port 43.

[0050] S4. Regeneration: Carbon dioxide or nitrogen at a temperature of 600°C is used as the regeneration gas, which enters from the regeneration gas inlet and desorbs carbon dioxide through the ceramic membrane tube to achieve regeneration of the ceramic membrane tube; the regeneration gas with desorbed carbon dioxide is discharged from the regeneration gas outlet and enters the subsequent process section.

[0051] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to it in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A device for capturing carbon dioxide in MTO regeneration flue gas, characterized in that It comprises a heat exchange zone (2), a dust removal and decarbonization zone (3), and a dust collection zone (4) which are sequentially arranged in the shell (1) from top to bottom; The upper portion of the heat exchange zone (2) is provided with an air inlet (5) for regeneration flue gas, and the lower portion is provided with a connecting pipe (7) for regeneration flue gas connected to the dust removal and decarbonization zone (3). The regeneration flue gas flows into the dust removal and decarbonization zone (3) after cooling through the heat exchange zone (2). The dust removal and decarbonization zone (3) is divided into two parts, the lower part is a coarse gas zone (31), and the upper part is a clean gas zone (32). The lower part of the coarse gas zone (31) is an air inlet chamber (36) connected to the connecting pipe (7). A gas redistributor (35) is provided above the air inlet chamber (36). A gas redistributor port (361) is provided on the gas redistributor (35). A ceramic membrane tube (34) is provided above the gas redistributor (35). A Venturi is provided in the clean gas zone (32). Tube (33), the ceramic membrane tube (34) is a plurality of tubes distributed below the Venturi tube (33); the regeneration flue gas enters the air inlet chamber (36), is rectified by the gas redistributor (35), and then enters the distribution area of ​​the ceramic membrane tube (34) through the gas redistribution port (361) for dust removal and decarbonization, and finally enters the Venturi tube (33) of the clean air zone through the ceramic membrane tube (34); the upper part of the clean air zone (32) is provided with a regeneration flue gas outlet (6), and the treated regeneration flue gas is discharged from the regeneration flue gas outlet (6); The dust collecting area (4) is provided with an ash collecting hopper (41), an ash discharging valve (42) and an ash discharging port (43); the ash collecting hopper (41) is provided below the air inlet chamber (36); dust falling from the dust removal and decarbonization area (3) enters the ash collecting hopper (41) and is discharged through the ash discharging valve (42) and the ash discharging port (43); The back-blowing system (10) further comprises a back-blowing system (10), the back-blowing system (10) comprising a blow gas inlet pipe (101), a pulse valve (102), a blow pipe (103), and a blow head (104) connected in sequence, the blow pipe (103) entering from the clean gas zone (32), and the blow head (104) being arranged in the venturi tube (33); The regeneration system further comprises a regeneration gas inlet (8) and a regeneration gas outlet (9), wherein the regeneration gas inlet is arranged at the bottom of the gas inlet chamber (36), and the regeneration gas outlet (9) is arranged at the upper part of the clean gas zone (32); The heat exchange zone (2) is provided with a heat exchange coil (21) and a baffle (22); The outer wall of the shell (1) is provided with a thermal insulation layer, which is a composite silicate thermal insulation material layer with a thickness of 50 to 300 mm; The inner wall of the dust removal and decarbonization zone (3) is built with refractory bricks; The ceramic membrane tube (34) is prepared according to the following steps: a) Place the mullite, cordierite, corundum, silicon oxide or silicon carbide ceramic dust removal membrane tube in a 20% to 60% citric acid, oxalic acid or hydrochloric acid solution and heat it in a microwave or water bath at 45 to 100°C for 0.4 to 6 hours, then clean it with ultrasonic waves and dry it; b) The carbon dioxide adsorption active component calcium ferrite is loaded into the pores of the ceramic dust removal membrane tube treated in a) above by a pressure impregnation method or a vacuum impregnation method, and then dried and calcined at 800 to 1400° C. for 1 to 8 hours to obtain a ceramic membrane tube (34).

2. The device for capturing carbon dioxide in MTO regeneration flue gas according to claim 1, characterized in that: The preparation method of the calcium ferrite comprises: dissolving ferric nitrate, calcium nitrate, C4H6O5 or C4H6O6 in water and ethanol to prepare a solution, and then adjusting the pH value of the solution to 7-9 with sodium hydroxide, ammonia water or ethylenediamine to obtain a calcium ferrite solution, wherein the molar ratio of the raw materials in the solution is Fe: Ca: C4H6O5 / C4H6O6=1:(1.5-1):(2-6).

3. The method for capturing carbon dioxide in MTO regeneration flue gas according to claim 1 or 2, characterized in that The steps include: S1. Input the MTO regeneration flue gas with a temperature of 550-700℃ into the heat exchange zone for heat exchange, and the temperature drops to 350-450℃ after heat exchange; S2. The MTO regeneration flue gas from the heat exchange area is transported to the air inlet chamber of the dust removal and decarbonization area, and enters the ceramic membrane tube distribution area after rectification by the gas redistributor. The dust and carbon dioxide in the MTO regeneration flue gas are captured and processed by the inner and outer surfaces of the ceramic membrane tube. The treated gas is discharged from the outlet of the clean gas area through the Venturi tube into the subsequent section.

4. The method for capturing carbon dioxide in MTO regeneration flue gas according to claim 3, characterized in that: After S1 and S2, the ceramic membrane tube is also regenerated: S3. Use room temperature air or nitrogen as backflush gas, which enters the Venturi tube from the injection gas inlet pipe to backflush and clean the ceramic membrane tube arranged below the Venturi tube, and blow the dust accumulated on the surface of the ceramic membrane tube into the dust collecting hopper in the dust collecting area; S4. Use carbon dioxide or nitrogen with a temperature of 550-650℃ as the regeneration gas, enter from the regeneration gas inlet, desorb carbon dioxide through the ceramic membrane tube to achieve ceramic membrane tube regeneration; the regeneration gas with desorbed carbon dioxide is discharged from the regeneration gas outlet and enters the subsequent process section.

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