Carbon dioxide capture and conversion integrated process method

Abstract

The invention discloses a carbon dioxide capture and conversion integrated process method, and relates to the technical field of carbon dioxide capture and conversion. A waste heat index is obtained through calculation according to a waste heat intensity calculation formula, when the waste heat of cooling water is insufficient, the cooling water can only be used for producing hot water, when the waste heat of the cooling water is sufficient, the cooling water can be used for process preheating and production heat, when the waste heat of the cooling water is too sufficient, and the safety performance of equipment needs to be noticed. And meanwhile, waste heat can be used for process preheating and production heat. The barren liquor enters from the top of the absorption tower, the total number of layers of the nozzles used when the barren liquor is sprayed downwards is set as follows, and after a specific value is calculated, when the industrial nozzles spray out the barren liquor, spraying holes are opened from the innermost layer to the first layer in sequence. The barren liquor is in countercurrent contact with flue gas entering from the bottom of the absorption tower in a descending process to absorb carbon dioxide in the flue gas to become rich liquor, and is discharged from the lower part of the absorption tower to enter a downstream process.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture and conversion technology, and in particular to an integrated process method for carbon dioxide capture and conversion. Background Technology

[0002] Integrated carbon dioxide capture and conversion to methane is an integrated technology that combines the direct capture of carbon dioxide at the emission source with the subsequent conversion of carbon dioxide to methane via catalytic hydrogenation, forming a continuous closed-loop system. This technology not only enables the resource utilization of carbon dioxide to produce methane, which can be used as a clean fuel or chemical feedstock, but also helps reduce greenhouse gas emissions, making it an important pathway to achieving carbon cycling and energy storage.

[0003] The existing integrated carbon dioxide capture and conversion methods generally have the following problems: (1) It is impossible to assess the waste heat of cooling water, so it is impossible to effectively and accurately utilize the waste heat in cooling water, resulting in a waste of thermal energy; (2) It is impossible to accurately adjust the diffusion degree of lean liquid spraying according to the pressure of industrial flue gas, so it is impossible to improve the absorption efficiency of carbon dioxide in industrial flue gas. If the flue gas pressure is low, the flue gas spray distance is insufficient, and the diffusion degree of lean liquid spraying is too large. Before the lean liquid comes into countercurrent contact with the flue gas, it will be sprayed onto the inner wall of the absorption tank, thereby reducing the contact area between the lean liquid and the flue gas; (3) In the existing technology, a single stripping tower structure is generally used for methane production, which cannot fully remove oxygen in the by-products, which may cause catalyst failure, inability to carry out reduction reaction and high temperature explosion hazards. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated process for carbon dioxide capture and conversion, aiming to solve the technical problems existing in the prior art, such as how to accurately assess the residual heat in cooling water, how to accurately adjust the diffusion degree during lean liquid spraying to improve the absorption efficiency of carbon dioxide, and how to fully remove oxygen from by-products.

[0005] To address the aforementioned technical problems, the present invention adopts the following technical solution: an integrated carbon dioxide capture and conversion process, comprising the following steps: Step S1: First, industrial flue gas is introduced into the flue gas inlet. The flue gas first passes through temperature and pressure sensors to detect its temperature and pressure. Then, the flue gas is cooled by a flue gas heat exchanger. The temperature of the flue gas heat exchanger is... The cooling water is circulated for cooling, reducing the temperature of the industrial flue gas to a certain level. ; Step S2: The cooled industrial flue gas then enters the Roots blower, where it is pressurized to the required pressure. The pressurized flue gas enters from the bottom of the absorption tower, and the lean liquid is sprayed downward from the top of the absorption tower and comes into countercurrent contact with the flue gas. The regular packing section set in the absorption tower will increase the contact area between the lean liquid and the flue gas, and improve the carbon dioxide absorption efficiency. The rich liquid that has absorbed carbon dioxide is discharged from the bottom of the absorption tower, and the flue gas tail gas is discharged from the top of the absorption tower. Step S3: The flue gas will enter the separator, where it will be separated into condensate and clean flue gas. The separated condensate will accumulate at the bottom of the separator and then flow into the condensate circulation pump. The condensate circulation pump will drive the condensate into the lean liquid and then follow the lean liquid into the absorption tower for recycling. Step S4: After step S3 is completed, the rich liquid that has absorbed carbon dioxide is pressurized by the rich liquid circulation pump and then exchanges heat with the lean and rich liquid heat exchanger to raise the temperature of the rich liquid. The final temperature after the temperature rise is... ; Step S5: The heated rich liquor enters the desorption and conversion tower. Through the action of the catalyst and the heating of the reboiler at the bottom of the desorption and conversion tower, carbon dioxide is desorbed from the rich liquor and partially converted into methane. Then, the mixed gas containing carbon dioxide, methane and lean liquor vapor is discharged from the top of the desorption and conversion tower into the separation chamber. The separation chamber then separates carbon dioxide, methane and lean liquor. The separated lean liquor then flows into the desorption and conversion tower through the lean liquor reflux pump. Step S6: The lean liquor remaining after analysis in the conversion tower will flow into the lean-rich liquor heat exchanger through the lean liquor circulation pump. Then the lean liquor will exchange heat with the rich liquor to realize the utilization of waste heat. Afterwards, the lean liquor will be cooled by the lean liquor cooler and flow into the upper end of the absorption tower, thereby realizing the recycling of the lean liquor.

[0006] Preferably, the temperature of the cooling water after heat exchange with the industrial flue gas is set to... When industrial flue gas is introduced into the flue gas inlet, the flue gas comes into contact with the gas mass flow meter. The gas mass flow meter then calculates the mass flow rate of the industrial flue gas using the thermal measurement principle. , The unit is kg / h. The industrial flue gas will then come into contact with a temperature detector at the flue gas inlet to measure the initial temperature of the industrial flue gas. ; The value is measured by a temperature detector; when cooling water enters the flue gas heat exchanger, it first comes into contact with the gas mass flow meter, which measures the mass flow rate of the cooling water as it flows in. , The unit is kg / h; then the waste heat index is calculated using the waste heat intensity calculation formula. The formula for calculating residual heat intensity is shown below: ; In the formula: Indicates the heat loss coefficient. The value range is from 0.85 to 0.95; min Indicates the lowest temperature at which waste heat can be utilized. min The value range is from 40℃ to 42℃; max Indicates the maximum tolerable temperature. max The value range is from 75℃ to 78℃; , , , The unit is ℃; The value range is from 24℃ to 28℃; This indicates the specific heat capacity of the flue gas. The value range is from 1.05 to 1.15. The unit is kilojoules per kilogram per degree Celsius; This indicates the specific heat capacity of cooling water. The value range is from 4.185 to 4.187. The unit is kilojoules per kilogram per degree Celsius; This represents the heat transfer efficiency coefficient. The value range is from 0.7 to 0.8; when When this occurs, it indicates that the flue gas heat exchanger is not working properly; when When the temperature is high, it indicates that the waste heat of the cooling water is insufficient and can only be used to produce hot water; when... When the temperature is high, it indicates that the residual heat of the cooling water is sufficient and can be used for process preheating and production heat; when... When this occurs, it indicates that the residual heat of the cooling water is too abundant, and attention should be paid to the safety performance of the equipment. At the same time, the residual heat can be used for process preheating and production heat.

[0007] Preferably, the temperature of the internal space of the separator is set to be ; The value is consistent with the temperature value of the external environment of the separator. The value is less than 36℃, and at the same time Greater than When the temperature is When industrial flue gas enters the separator, the water vapor in the industrial flue gas will come into contact with the inner wall of the separator and form condensate. The value ranges from 20 kPa to 50 kPa.

[0008] Preferably, during the process of spraying lean liquor downwards from the top of the absorption tower, the lean liquor is sprayed through an industrial nozzle with multiple concentric spray holes. The spray holes on the industrial nozzle are arranged circumferentially, and simultaneously, the spray holes form a radial pattern along the industrial nozzle. Layer upon layer; industrial nozzles are designed based on the number of layers. The nozzles come in three sizes: large, medium, and small. The large nozzle has a different number of spray rings. The value is 25, which represents the number of rings in the nozzle. The value is 15, which represents the number of rings in the small nozzle. The value is 5; when the industrial flue gas flow rate is less than half of the daily average flow rate, a small nozzle is used; when the industrial flue gas flow rate is greater than or equal to half of the daily average flow rate and less than or equal to twice the daily average flow rate, a medium nozzle is used; when the industrial flue gas flow rate is greater than twice the daily average flow rate, a large nozzle is used.

[0009] Preferably, the total number of nozzle rings used when spraying lean liquid downwards is set to... for; The calculation formula is as follows: ; In the formula: Indicates rounding down; Indicates the growth coefficient. The value of is an odd number greater than or equal to 1 and less than or equal to 5; when calculated... After the specific values ​​are determined, when the industrial nozzle sprays lean liquid, it will open the nozzle from the innermost ring, sequentially opening up to the next ring. Layer upon layer; in the future Substitute into When performing calculations in the formula, only substitute... The value.

[0010] Preferably, the rich solution circulation pump adopts a dual-pump design, consisting of a working pump and a standby pump; when pressurizing the rich solution, the rich solution circulation pump needs to increase the pressure of the rich solution to a certain level. , The value range is from 200 kPa to 400 kPa; The value range is from 80℃ to 90℃.

[0011] Preferably, when the desorption and conversion tower is working, the interior of the desorption and conversion tower is under atmospheric pressure; multiple reaction plates are arranged inside the desorption tower from top to bottom; when the rich liquid flows down inside the desorption tower, the reaction plates will slow down the flow rate of the solution, thereby increasing the degree of reaction; the reaction plates are also filled with catalyst; a bottom solution is provided at the bottom of the desorption and conversion tower, which contains catalyst and lean liquid.

[0012] Preferably, the desorption and conversion tower adopts a dual-tower design, consisting of a primary conversion tower and a secondary conversion tower. The primary conversion tower is responsible for desorbing all the carbon dioxide in the rich solution and partially converting it into methane. The secondary conversion tower desorbs the oxygen-containing components absorbed in the solution. The oxygen-evolved solution becomes a lean solution and is discharged into the absorption tower for recycling through a lean solution circulation pump. The reboiler is used for heating and heat preservation of the bottom solution.

[0013] The beneficial effects of this invention compared with the prior art are: (1) the waste heat index is then calculated using the waste heat intensity calculation formula. ,when When the temperature is high, it indicates that the waste heat of the cooling water is insufficient and can only be used to produce hot water; when... When the temperature is high, it indicates that the residual heat of the cooling water is sufficient and can be used for process preheating and production heat; when... When this occurs, it indicates that the residual heat of the cooling water is too abundant, and attention should be paid to the safety performance of the equipment. At the same time, the residual heat can be used for process preheating and production heat. (2) Industrial nozzles are based on the number of ring layers. The nozzles come in three sizes: large, medium, and small. The large nozzle has a different number of spray rings. The value is 25, which represents the number of rings in the nozzle. The value is 15, which represents the number of rings in the small nozzle. The value is 5; when the inflow of industrial flue gas is less than half of the daily average inflow, small nozzles are used in the industrial spray; when the inflow of industrial flue gas is greater than or equal to half of the daily average inflow and less than or equal to twice the daily average inflow, medium nozzles are used in the industrial spray; when the inflow of industrial flue gas is greater than twice the daily average inflow, large nozzles are used in the industrial spray. (3) The lean liquid enters from the top of the absorption tower. Let the total number of nozzle rings used when spraying the lean liquid downwards be 5. When calculated After the specific values ​​are determined, when the industrial nozzle sprays lean liquid, it will open the nozzle from the innermost ring, sequentially opening up to the next ring. Layer upon layer; the rich liquid mainly contains ammonium carbonate, ammonium bicarbonate, physically dissolved carbon dioxide, physically dissolved nitrogen and physically dissolved oxygen. (4) During the descent process, the lean liquid comes into countercurrent contact with the flue gas entering from the bottom of the absorber and absorbs the carbon dioxide in the flue gas to become rich liquid, which is then discharged from the bottom of the absorber and enters the downstream process. Attached Figure Description

[0014] Figure 1 This is a flowchart of the integrated carbon dioxide capture and conversion process of the present invention.

[0015] Figure 2 This is a schematic diagram of the core equipment of the present invention.

[0016] In the diagram: 1-Flue gas heat exchanger; 2-Separating tank; 3-Roots blower; 4-Absorber; 5-Rich liquor circulation pump; 6-Rich and lean liquor heat exchanger; 7-Analysis conversion tower; 8-Reboiler; 9-Condensate circulation pump; 10-Lean liquor cooler; 11-Lean liquor circulation pump; 12-Separating chamber; 13-Lean liquor reflux pump. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0019] Figure 1 and Figure 2 This is a preferred embodiment of the present invention.

[0020] Figure 1 A flowchart of the integrated carbon dioxide capture and conversion process of the present invention is provided, including the following steps: Step S1: First, industrial flue gas is introduced into the flue gas inlet. The flue gas first passes through temperature and pressure sensors to detect its temperature and pressure. Then, the flue gas passes through flue gas heat exchanger 1 for cooling. Flue gas heat exchanger 1 uses a temperature of... The cooling water is circulated for cooling, reducing the temperature of the industrial flue gas to a certain level. ; Step S2: The cooled industrial flue gas then enters the Roots blower 3, where it is pressurized to the required pressure. The pressurized flue gas enters from the bottom of the absorption tower 4, and the lean liquid is sprayed downward from the top of the absorption tower 4 and comes into countercurrent contact with the flue gas. The regular packing section set in the absorption tower 4 will increase the contact area between the lean liquid and the flue gas, and improve the carbon dioxide absorption efficiency. The rich liquid that has absorbed carbon dioxide is discharged from the bottom of the absorption tower 4, and the flue gas tail gas is discharged from the top of the absorption tower 4. Step S3: The flue gas will enter the separator 2, and then be separated into condensate and clean flue gas in the separator 2. The separated condensate will accumulate at the bottom of the separator 2, and then flow from the bottom of the separator 2 into the condensate circulation pump 9. The condensate circulation pump 9 will drive the condensate to be incorporated into the lean liquid, and then follow the lean liquid into the absorption tower 4 for recycling. Step S4: After step S3 is completed, the rich liquid that has absorbed carbon dioxide is pressurized by the rich liquid circulation pump 5 and then exchanges heat with the lean and rich liquid heat exchanger 6 to raise the temperature of the rich liquid. The final temperature after the temperature rise is... ; Step S5: The heated rich liquor enters the desorption and conversion tower 7. Through the action of the catalyst and the heating of the reboiler 8 at the bottom of the desorption and conversion tower 7, carbon dioxide is desorbed from the rich liquor and partially converted into methane. Then, the mixed gas containing carbon dioxide, methane and lean liquor vapor is discharged from the top of the desorption and conversion tower 7 into the separation chamber 12. The separation chamber 12 then separates carbon dioxide, methane and lean liquor. The separated lean liquor then flows into the desorption and conversion tower 7 through the lean liquor reflux pump 13. Step S6: The lean liquor remaining in the analysis and conversion tower 7 after analysis will flow into the lean and rich liquor heat exchanger 6 through the lean liquor circulation pump 11. Then the lean liquor will exchange heat with the rich liquor to realize the utilization of waste heat. Afterwards, the lean liquor will be cooled by the lean liquor cooler 10 and flow into the upper end of the absorption tower 4, thereby realizing the recycling of the lean liquor.

[0021] The working principle of this invention is as follows: First, industrial flue gas is introduced into the flue gas inlet. The flue gas then passes through temperature and pressure sensors to detect its temperature and pressure. Subsequently, the flue gas is cooled by a flue gas heat exchanger 1, which operates at a temperature of [temperature value missing]. The cooling water is circulated for cooling, reducing the temperature of the industrial flue gas to a certain level. The cooled industrial flue gas then enters the Roots blower 3, where it is pressurized to a certain pressure. The pressurized flue gas enters from the bottom of absorption tower 4, while the lean liquor is sprayed downwards from the top of absorption tower 4 and comes into countercurrent contact with the flue gas. The structured packing section in absorption tower 4 increases the contact area between the lean liquor and the flue gas, improving the carbon dioxide absorption efficiency. The rich liquor, which has absorbed carbon dioxide, is discharged from the bottom of absorption tower 4, while the flue gas exhaust is discharged from the top of absorption tower 4. The flue gas exhaust enters the separator 2, where it is separated into condensate and clean flue gas. The separated condensate accumulates at the bottom of separator 2 and then flows into condensate circulation pump 9. Condensate circulation pump 9 carries the condensate into the lean liquor, which then follows the lean liquor into absorption tower 4 for recycling. Subsequently, the rich liquor, which has absorbed carbon dioxide, is pressurized by rich liquor circulation pump 5 and exchanges heat with the lean-rich liquor heat exchanger 6, raising the temperature of the rich liquor. The final temperature after heating is [temperature missing]. The heated rich liquor enters the desorption and conversion tower 7. Through the action of the catalyst and the heating of the reboiler 8 at the bottom of the desorption and conversion tower 7, carbon dioxide is desorbed from the rich liquor and partially converted into methane. Then, the mixed gas containing carbon dioxide, methane and lean liquor vapor is discharged from the top of the desorption and conversion tower 7 into the separation chamber 12. The separation chamber 12 then separates the carbon dioxide and methane from the lean liquor. The separated lean liquor then flows into the desorption and conversion tower 7 through the lean liquor reflux pump 13. The lean liquor remaining in the desorption and conversion tower 7 after desorption flows into the lean-rich liquor heat exchanger 6 through the lean liquor circulation pump 11. Then, the lean liquor exchanges heat with the rich liquor to realize the utilization of waste heat. Then, the lean liquor is cooled by the lean liquor cooler 10 and flows into the upper end of the absorption tower 4, thereby realizing the recycling of the lean liquor.

[0022] Furthermore, let the temperature of the cooling water after heat exchange with the industrial flue gas be... When industrial flue gas is introduced into the flue gas inlet, the flue gas comes into contact with the gas mass flow meter. The gas mass flow meter then calculates the mass flow rate of the industrial flue gas using the thermal measurement principle. , The unit is kg / h. The industrial flue gas will then come into contact with a temperature detector at the flue gas inlet to measure the initial temperature of the industrial flue gas. ; The value is measured by a temperature detector; when cooling water enters the flue gas heat exchanger 1, it first comes into contact with the gas mass flow meter, which measures the mass flow rate of the cooling water as it flows in. , The unit is kg / h; then the waste heat index is calculated using the waste heat intensity calculation formula. The formula for calculating residual heat intensity is as follows: ; In the formula: Indicates the heat loss coefficient. The value range is from 0.85 to 0.95; min Indicates the lowest temperature at which waste heat can be utilized. min The value range is from 40℃ to 42℃; max Indicates the maximum tolerable temperature. max The value range is from 75℃ to 78℃; , , , The unit is ℃; The value range is from 24℃ to 28℃; This indicates the specific heat capacity of the flue gas. The value range is from 1.05 to 1.15. The unit is kilojoules per kilogram per degree Celsius; This indicates the specific heat capacity of cooling water. The value range is from 4.185 to 4.187. The unit is kilojoules per kilogram per degree Celsius; This represents the heat transfer efficiency coefficient. The value range is from 0.7 to 0.8; when When this occurs, it indicates that flue gas heat exchanger 1 is not working properly; when When the temperature is high, it indicates that the waste heat of the cooling water is insufficient and can only be used to produce hot water; when... When the temperature is high, it indicates that the residual heat of the cooling water is sufficient and can be used for process preheating and production heat; when... When this occurs, it indicates that the waste heat from the cooling water is too abundant, requiring attention to the equipment's safety performance. Simultaneously, the waste heat can be used for process preheating and production heating. The value is 25℃. The value is 120℃. The value is 60℃. The value is 0.75. The value range is 0.9. min The value is 40℃. max The value is 75℃. The value is 1.05 kJ per kilogram per degree Celsius. The value is 4.185 kJ per kilogram per degree Celsius. and When the ratio is 2, The calculated result is 47.58℃, and the waste heat index is... The calculation result is 0.5092, indicating that the waste heat of the cooling water can only be used to produce hot water at this time.

[0023] Furthermore, let the temperature of the internal space of the separator 2 be... ; The value is consistent with the temperature value of the external environment of the separator 2. The value is less than 36℃, and at the same time Greater than When the temperature is When industrial flue gas enters the separator 2, the water vapor in the industrial flue gas will come into contact with the inner wall of the separator 2 and form condensate. The value ranges from 20 kPa to 50 kPa.

[0024] Furthermore, during the process of the lean liquor being sprayed downwards from the top of the absorption tower 4, the lean liquor is sprayed through an industrial nozzle with multiple concentric rings of nozzles. The nozzles on the industrial nozzle are arranged circumferentially, and simultaneously, the nozzles form a radial pattern along the industrial nozzle. Layer upon layer; industrial nozzles are designed based on the number of layers. The nozzles come in three sizes: large, medium, and small. The large nozzle has a different number of spray rings. The value is 25, which represents the number of rings in the nozzle. The value is 15, which represents the number of rings in the small nozzle. The value is 5; when the industrial flue gas flow rate is less than half of the daily average flow rate, a small nozzle is used; when the industrial flue gas flow rate is greater than or equal to half of the daily average flow rate and less than or equal to twice the daily average flow rate, a medium nozzle is used; when the industrial flue gas flow rate is greater than twice the daily average flow rate, a large nozzle is used.

[0025] Furthermore, let the total number of nozzle rings used when spraying the lean solution downwards be... ; The calculation formula is as follows: ; In the formula: Indicates rounding down; Indicates the growth coefficient. The value of is an odd number greater than or equal to 1 and less than or equal to 5; when calculated... After the specific values ​​are determined, when the industrial nozzle sprays lean liquid, it will open the nozzle from the innermost ring, sequentially opening up to the next ring. Layer upon layer; in the future Substitute into When performing calculations in the formula, only substitute... The value; when The value is 24 kPa. The value is 5. When the value is 1, The calculation result is 1; when The value is 40 kPa. The value is 25. When the value is 1, The calculation result is 15; when The value is 40 kPa. The value is 25. When the value is 3, The calculation result is 6; when The value is 50 kPa. The value is 15. When the value is 1, The calculated result is 15.

[0026] Furthermore, the rich solution circulation pump 5 adopts a dual-pump design, consisting of a working pump and a standby pump; when pressurizing the rich solution, the rich solution circulation pump 5 needs to increase the pressure of the rich solution to a certain level. , The value range is from 200 kPa to 400 kPa; The value range is from 80℃ to 90℃.

[0027] Furthermore, when the stripping conversion tower 7 is working, the interior of the stripping conversion tower 7 is under atmospheric pressure; multiple reaction plates are arranged inside the stripping tower from top to bottom; when the rich liquid flows down inside the stripping tower, the reaction plates will slow down the flow rate of the solution, thereby increasing the degree of reaction; the reaction plates are also filled with catalyst; a bottom solution is set at the bottom of the stripping conversion tower 7, which contains catalyst and lean liquid.

[0028] Furthermore, the analysis and conversion tower 7 adopts a dual-tower design, consisting of a primary conversion tower and a secondary conversion tower. The primary conversion tower is responsible for completely analyzing the carbon dioxide in the rich solution and partially converting it into methane. The secondary conversion tower analyzes the oxygen-containing components absorbed in the solution. The oxygen-evolved solution becomes a lean solution and is discharged into the absorption tower 4 for recycling via the lean solution circulation pump 11. The reboiler 8 is used for heating and heat preservation of the bottom solution.

[0029] This invention is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort are within the protection scope of this invention.

Claims

1. An integrated process for carbon dioxide capture and conversion, characterized in that, Includes the following steps: Step S1: First, industrial flue gas is introduced into the flue gas inlet. At this time, the industrial flue gas will first pass through the temperature sensor and pressure sensor to detect the temperature and pressure of the industrial flue gas. Then, the industrial flue gas is cooled by the flue gas heat exchanger (1). The flue gas heat exchanger (1) adopts a temperature of The cooling water is circulated for cooling, reducing the temperature of the industrial flue gas to a certain level. ; Step S2: The cooled industrial flue gas then enters the Roots blower (3), and the Roots blower (3) pressurizes the flue gas to the required pressure. Pressurized flue gas enters from the bottom of the absorption tower (4), lean liquid is sprayed downward from the top of the absorption tower (4) and comes into countercurrent contact with the flue gas. The regular packing section set in the absorption tower (4) will increase the contact area between the lean liquid and the flue gas, improve the carbon dioxide absorption efficiency, and the rich liquid that has absorbed carbon dioxide is discharged from the bottom of the absorption tower (4), and the flue gas tail gas is discharged from the top of the absorption tower (4). Step S3: The flue gas will enter the separator (2), and then be separated into condensate and clean flue gas in the separator (2). The separated condensate will accumulate at the bottom of the separator (2), and then flow from the bottom of the separator (2) into the condensate circulation pump (9). The condensate circulation pump (9) will drive the condensate into the lean liquid, and then follow the lean liquid into the absorption tower (4) for recycling. Step S4: After step S3 is completed, the rich liquid that has absorbed carbon dioxide is pressurized by the rich liquid circulation pump (5) and then exchanged with the lean and rich liquid heat exchanger (6) to raise the temperature of the rich liquid. The final temperature after the temperature rise is ; Step S5: The heated rich liquid will enter the desorption and conversion tower (7). Through the action of the catalyst and the heating of the reboiler (8) at the bottom of the desorption and conversion tower (7), carbon dioxide will be desorbed from the rich liquid and partially converted into methane. Then, the mixed gas containing carbon dioxide, methane and lean liquid vapor will be discharged from the top of the desorption and conversion tower (7) into the separation chamber (12). Then, the separation chamber (12) will separate carbon dioxide, methane and lean liquid. Then, the separated lean liquid will flow into the desorption and conversion tower (7) through the lean liquid reflux pump (13). Step S6: The lean liquid remaining in the conversion tower (7) after analysis will flow into the lean and rich liquid heat exchanger (6) through the lean liquid circulation pump (11). Then the lean liquid will exchange heat with the rich liquid to realize the utilization of waste heat. Afterwards, the lean liquid will be cooled by the lean liquid cooler (10) and flow into the upper end of the absorption tower (4) to realize the recycling of the lean liquid.

2. The integrated carbon dioxide capture and conversion process as described in claim 1, characterized in that: Assume the temperature of the cooling water after heat exchange with the industrial flue gas is... When industrial flue gas is introduced into the flue gas inlet, the flue gas comes into contact with the gas mass flow meter. The gas mass flow meter then calculates the mass flow rate of the industrial flue gas using the thermal measurement principle. , The unit is kg / h. The industrial flue gas will then come into contact with a temperature detector at the flue gas inlet to measure the initial temperature of the industrial flue gas. ; The value is obtained by a temperature detector; when the cooling water enters the flue gas heat exchanger (1), it will first come into contact with the gas mass flow meter, and the gas mass flow meter will measure the mass flow rate of the cooling water when it flows in. , The unit is kg / h; then the waste heat index is calculated using the waste heat intensity calculation formula. The formula for calculating residual heat intensity is as follows: ； In the formula: Indicates the heat loss coefficient. The value range is from 0.85 to 0.95; min Indicates the lowest temperature at which waste heat can be utilized. min The value range is from 40℃ to 42℃; max Indicates the maximum tolerable temperature. max The value range is from 75℃ to 78℃; , , , The unit is ℃; The value range is from 24℃ to 28℃; This indicates the specific heat capacity of the flue gas. The value range is from 1.05 to 1.

15. The unit is kilojoules per kilogram per degree Celsius; This indicates the specific heat capacity of cooling water. The value range is from 4.185 to 4.

187. The unit is kilojoules per kilogram per degree Celsius; This represents the heat transfer efficiency coefficient. The value range is from 0.7 to 0.8; when When this occurs, it indicates that the flue gas heat exchanger (1) is not working properly; when When the temperature is high, it indicates that the waste heat of the cooling water is insufficient and can only be used to produce hot water; when... When the temperature is high, it indicates that the residual heat of the cooling water is sufficient and can be used for process preheating and production heat; when... When this occurs, it indicates that the residual heat of the cooling water is too abundant, and attention should be paid to the safety performance of the equipment. At the same time, the residual heat can be used for process preheating and production heat.

3. The integrated carbon dioxide capture and conversion process as described in claim 2, characterized in that: Let the temperature of the internal space of the separator (2) be... ; The value is consistent with the temperature value of the external environment of the separator (2). The value is less than 36℃, and at the same time Greater than When the temperature is When industrial flue gas enters the separator (2), the water vapor in the industrial flue gas will come into contact with the inner wall of the separator (2) and form condensate; The value ranges from 20 kPa to 50 kPa.

4. The integrated carbon dioxide capture and conversion process as described in claim 3, characterized in that: During the process of the lean liquor being sprayed downwards from the top of the absorption tower (4), the lean liquor is sprayed through an industrial nozzle with multiple concentric spray holes. The spray holes on the industrial nozzle are arranged in a circumferential direction, and at the same time, the spray holes are arranged in a radial direction along the industrial nozzle to form a total of Layer upon layer; industrial nozzles are designed based on the number of layers. The nozzles come in three sizes: large, medium, and small. The large nozzle has a different number of spray rings. The value is 25, which represents the number of rings in the nozzle. The value is 15, which represents the number of rings in the small nozzle. The value is 5; when the industrial flue gas flow rate is less than half of the daily average flow rate, a small nozzle is used; when the industrial flue gas flow rate is greater than or equal to half of the daily average flow rate and less than or equal to twice the daily average flow rate, a medium nozzle is used; when the industrial flue gas flow rate is greater than twice the daily average flow rate, a large nozzle is used.

5. The integrated carbon dioxide capture and conversion process as described in claim 4, characterized in that: Let the total number of nozzle rings used when spraying lean liquid downwards be . ; The calculation formula is as follows: ； In the formula: Indicates rounding down; Indicates the growth coefficient. The value of is an odd number greater than or equal to 1 and less than or equal to 5; when calculated... After the specific values ​​are determined, when the industrial nozzle sprays lean liquid, it will open the nozzle from the innermost ring, sequentially opening up to the next ring. Layer upon layer; in the future Substitute into When performing calculations in the formula, only substitute... The value.

6. The integrated carbon dioxide capture and conversion process as described in claim 5, characterized in that: The rich liquid circulation pump (5) adopts a dual-pump design, consisting of a working pump and a standby pump; when pressurizing the rich liquid, the rich liquid circulation pump (5) needs to increase the pressure of the rich liquid to the required pressure. , The value range is from 200 kPa to 400 kPa; The value range is from 80℃ to 90℃.

7. The integrated carbon dioxide capture and conversion process as described in claim 6, characterized in that: When the desorption conversion tower (7) is working, the interior of the desorption conversion tower (7) is under normal pressure; multiple reaction plates are arranged inside the desorption tower from top to bottom; when the rich liquid flows down inside the desorption tower, the reaction plates will slow down the flow rate of the solution, thereby increasing the degree of reaction; the reaction plates are also filled with catalyst; a bottom solution is arranged at the bottom of the desorption conversion tower (7), which contains catalyst and lean liquid.

8. A carbon dioxide capture and conversion integrated process method based on claim 7, characterized in that: The analysis and conversion tower (7) adopts a dual-tower design, which is divided into a primary conversion tower and a secondary conversion tower. The primary conversion tower is responsible for analyzing all the carbon dioxide in the rich solution and partially converting it into methane. The secondary conversion tower analyzes the oxygen-containing components absorbed in the solution. The oxygen-evolved solution becomes a lean solution and is discharged into the absorption tower (4) for recycling through the lean solution circulation pump (11). The reboiler (8) is used for heating and heat preservation of the bottom solution.

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