Membrane method carbon capturing and curing method

Abstract

The invention provides a membrane-method carbon capture and solidification method. The membrane-method carbon capture and solidification method comprises a multivalent separation electrodialysis system, a cationic resin column, a bipolar membrane electrodialysis system, a carbon dioxide membrane enrichment device, an absorption tower, a pregnant solution pump, a desorption tower and four-compartment replacement electrodialysis. Alkali produced by bipolar membrane electrodialysis is used as absorption liquid, and acid produced by bipolar membrane electrodialysis is used as desorption liquid. According to the invention, the use cost of the adsorbent and the desorption agent is reduced, the internal balance of the agent system is realized, and meanwhile, the preparation of high-purity potassium bicarbonate can be realized by combining with four-compartment replacement electrodialysis. The system can be used for capturing and purifying carbon dioxide in atmosphere or industrial production and refining a potassium bicarbonate product, and compared with traditional carbon capture, absorption liquid and desorption liquid in the system can achieve circulation in the system, and zero emission is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon capture and carbon capture and utilization, and relates to membrane-based carbon capture and solidification, and particularly to a membrane-based carbon capture and solidification method for reducing the use cost of adsorbents and desorbents and achieving internal balance in the reagent system. Background Art

[0002] Currently, about 51 billion tons of greenhouse gases are emitted into the atmosphere globally every year. To avoid climate disasters, humans need to stop emitting greenhouse gases into the atmosphere and achieve zero emissions.

[0003] With the growth of industrialization and energy consumption, carbon emissions are constantly rising. More and more countries have elevated "carbon neutrality" to a national strategy and put forward the vision of a carbon-free future. The resulting carbon capture methods are mainly carbon capture and storage (CCS) or chemical absorption methods.

[0004] Patent Publication No. CN117815843A, an invention patent named a carbon capture system and its control method, proposes a carbon capture system and its control method. The carbon capture device includes an absorption tower, a rich liquid pump, and a desorption tower connected in sequence. The absorption tower captures carbon dioxide through an absorption liquid, and the desorption tower desorbs carbon dioxide through a desorption liquid, thereby achieving the capture and release of carbon dioxide. However, the defect of this patent is that a large amount of absorption liquid and desorption liquid need to be added, and the absorption liquid and desorption liquid consume each other, resulting in a high cost. Summary of the Invention

[0005] To solve the problems of the need to add a large amount of absorption liquid and desorption liquid, the mutual consumption of the absorption liquid and desorption liquid, and the high cost, the present invention provides a membrane-based carbon capture and solidification method. The membrane-based carbon capture and solidification of the present invention includes: a multi-valent separation electrodialysis system, a cation resin column, a bipolar membrane electrodialysis system, a carbon dioxide membrane enrichment device, an absorption tower, a rich liquid pump, a desorption tower, and a four-compartment displacement electrodialysis. The alkali produced by the bipolar membrane electrodialysis serves as the absorption liquid, and the acid produced serves as the desorption liquid. The present invention reduces the use cost of adsorbents and desorbents, achieves internal balance in the reagent system, and can also be combined with four-compartment displacement electrodialysis to produce high-purity potassium bicarbonate.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a membrane-based carbon capture and solidification method, and the method includes the following steps:

[0008] 1) Separating and concentrating seawater through a separation electrodialysis system to obtain concentrated water containing high-concentration monovalent ion chloride salts and fresh water containing multi-valent metal ions respectively;

[0009] 2) Passing the concentrated water obtained in step 1) through a cation resin column;

[0010] 3) The concentrated water obtained in step 2) is used to prepare acid solution and alkali solution by a bipolar membrane electrodialysis system;

[0011] 4) Separate carbon dioxide from other gases through an enrichment device to increase the concentration of carbon dioxide;

[0012] 5) Feed the carbon dioxide enriched in step 4) into an absorption tower device for carbon capture. The alkali solution obtained in step 3) is used as the absorption liquid to control the ventilation residence time to obtain a rich liquid;

[0013] 6) Pump the rich liquid obtained from the absorption tower device into a desorption tower device, and release carbon dioxide through the acid solution obtained in step 3) to obtain high-purity carbon dioxide gas;

[0014] Or step 6) is replaced by step 7);

[0015] 7) Pump the rich liquid obtained from the absorption tower device into a four-compartment displacement electrodialysis, and displace it with a potassium chloride solution to obtain a high-purity potassium bicarbonate solution.

[0016] As a preferred embodiment of the present invention, in step 1), the separation electrodialysis system is a multi-valent separation electrodialysis system; the initial fresh water chamber is added with the salt concentration of the extracted seawater of 2-3.5%, the concentrated water is added with pure water, and finally the fresh water is reduced to 1-1.5%, and the concentrated water is increased to 8-15%.

[0017] As a preferred embodiment of the present invention, in step 2), for the cation resin column, the resin filled is one of DOWEX D262, POLY-SPHER 550, Purolite S-960, Zheng Guang, Su Qing 402, Lan Xiao 500 or Kehai Si CH-93. The content of the feed multi-valent metal ions is 10-30 ppm, the column passing flow rate is 5-25 m / h, and the pH is 4-10.

[0018] As a preferred embodiment of the present invention, in step 3), the bipolar membrane electrodialysis system successively includes a positive electrode plate, a polar membrane spacer, a polar membrane, a spacer, a bipolar membrane, a spacer, an anion exchange membrane, a spacer, a cation exchange membrane, a spacer, a bipolar membrane, a spacer, an anion exchange membrane, a spacer, a cation exchange membrane, a spacer,... bipolar membrane, spacer, cation exchange membrane, spacer, polar membrane, polar membrane spacer and a negative electrode plate; wherein, the bipolar membrane, the anion exchange membrane and the cation exchange membrane together form a unit. The bipolar membrane and the anion exchange membrane form an acid chamber, the anion exchange membrane and the cation exchange membrane form a material chamber, the cation exchange membrane and the bipolar membrane form an alkali chamber, the polar membrane and the electrode plate form a polar water chamber. The material chamber, the acid chamber, the alkali chamber and the polar water chamber are independent of each other, and the operating temperature is 0-35°C.

[0019] As a preferred embodiment of the present invention, the material chamber contains the concentrated water obtained in step 2), and the electrode chamber contains an alkali solution with a concentration of 2-4%.

[0020] As a preferred embodiment of the present invention, in step 4), the enrichment device includes a gas pressurization device and a carbon capture membrane module; wherein, the carbon capture membrane module includes an air inlet, a permeate outlet, and a retentate outlet, the inlet CO2 concentration is 0.03-30%, the parameters of the gas pressurization device are 30-80 bar, and the carbon capture membrane is a polymer membrane.

[0021] As a preferred embodiment of the present invention, the inlet CO2 concentration is 5-30%.

[0022] As a preferred embodiment of the present invention, in step 5), the absorption tower device includes an air inlet, an aeration device, a plurality of serially connected absorption towers, a pH monitoring system, a carbon dioxide monitoring system, and an exhaust outlet.

[0023] As a preferred embodiment of the present invention, in step 6), the desorption tower device includes an acid addition valve, a hydraulic stirring device, a pH monitoring system, a carbon dioxide monitoring system, and an exhaust outlet, the desorbing liquid is the acid liquid obtained in step 3), and the pH at the end point of complete CO2 desorption is 3-4.

[0024] As a preferred embodiment of the present invention, in step 7), the four-compartment displacement electrodialysis device successively includes a positive electrode plate, an electrode membrane spacer, an electrode membrane, a spacer, an anion exchange membrane 1, a spacer, a cation exchange membrane 1, a spacer, an anion exchange membrane 2, a spacer, a cation exchange membrane 2, a spacer, an anion exchange membrane 1, a spacer, a cation exchange membrane 1, a spacer,... anion exchange membrane 2, a spacer, a cation exchange membrane 2, a spacer, an electrode membrane, an electrode membrane spacer, and a negative electrode plate; wherein, the anion exchange membrane 1, the cation exchange membrane 1, the anion exchange membrane 2, and the cation exchange membrane 2 together form a unit, the anion exchange membrane 1 and the cation exchange membrane 1 form a dilute chamber 1, the cation exchange membrane 1 and the anion exchange membrane 2 form a concentrated chamber 1, the anion exchange membrane 2 and the cation exchange membrane 2 form a dilute chamber 2, the cation exchange membrane 2 and the anion exchange membrane 1 form a concentrated chamber 2, and the electrode membrane and the electrode plate form an electrode chamber.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) The present invention can be used for the capture and purification of carbon dioxide in the atmosphere or industrial production, as well as the refining of potassium bicarbonate products. Compared with traditional carbon capture, both the absorption liquid and the desorbing liquid in the system can be recycled within the system, achieving zero emissions.

[0027] 2) The present invention can capture and purify CO2 to ensure the quality of downstream processes.

[0028] 3) The fresh water produced by the multi-valent separation electrodialysis system of the present invention can be further desalinated to reduce the load of the seawater desalination process.

[0029] 4) The rich solution obtained by the present invention can produce a more valuable potassium bicarbonate product through displacement electrodialysis with potassium chloride.

[0030] 5) The present invention reduces the use cost of the adsorbent desorbent and realizes the balance within the medicament system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a schematic diagram of the multi-valent rectifying electrodialysis of the present invention.

[0033] Figure 2 It is a schematic diagram of the bipolar membrane electrodialysis of the present invention.

[0034] Figure 3 It is a schematic diagram of the carbon capture membrane of the present invention.

[0035] Figure 4 It is a schematic diagram of the four-compartment displacement electrodialysis of the present invention.

[0036] Figure 5 It is a flow chart of Embodiment 1 of the present invention.

[0037] Figure 6 It is a flow chart of Embodiment 2 of the present invention.

[0038] Figure 7 It is a device diagram of Embodiment 1 of the present invention.

[0039] Figure 8 It is a device diagram of Embodiment 2 of the present invention.

[0040] In the figure, 1. A multi-valent separation electrodialysis system; 2. A concentrated brine lift pump; 3. A resin tank; 4. An impurity-removing brine lift pump; 5. A bipolar membrane electrodialysis system; 6. An absorption tower device; 7. A pressurizing device; 8. A membrane capture device; 9. A desorption pump; 10. A rich solution pump; 11. A desorption tower device; 12. A four-compartment displacement electrodialysis system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] Based on the defects that the existing carbon capture methods require a large amount of addition of absorbent and desorbent, and the absorbent and desorbent consume each other and the cost is relatively high, the present invention provides a membrane-based carbon capture and solidification method. The system used in the present invention includes a membrane-based carbon capture and solidification, including: a multi-valent separation electrodialysis system, a cation resin column, a bipolar membrane electrodialysis system, a carbon dioxide membrane enrichment device, an absorption tower, a rich liquid pump, a desorption tower, and / or a four-compartment displacement electrodialysis. The alkali produced by the bipolar membrane electrodialysis is used as the absorbent, and the acid produced is used as the desorbent.

[0043] That is, the method of the present invention can desorb the rich liquid obtained through the above system to separately collect carbon dioxide gas with a relatively high purity, or the rich liquid obtained through the above system can be displaced with a potassium chloride solution to obtain a high-purity potassium bicarbonate solution.

[0044] Therefore, the membrane-based carbon capture and solidification method of the present invention includes the following steps:

[0045] 1) Separate and concentrate seawater through a separation electrodialysis system to obtain concentrated water containing a high concentration of monovalent ion chloride salts and fresh water containing multi-valent metal ions respectively;

[0046] 2) Pass the concentrated water obtained in step 1) through a cation resin column;

[0047] 3) Prepare acid solution and alkali solution from the concentrated water obtained in step 2) using a bipolar membrane electrodialysis system;

[0048] 4) Separate carbon dioxide from other gases through an enrichment device to increase the concentration of carbon dioxide;

[0049] 5) Feed the carbon dioxide enriched in step 4) into an absorption tower device for carbon capture, and use the alkali solution obtained in step 3) as the absorbent to control the ventilation residence time to obtain rich liquid;

[0050] 6) Pump the rich liquid obtained from the absorption tower device into a desorption tower device, and release carbon dioxide using the acid solution obtained in step 3) to obtain high-purity carbon dioxide gas;

[0051] Or step 6) is replaced by step 7);

[0052] 7) Pump the rich liquid obtained from the absorption tower device into a four-compartment displacement electrodialysis, and displace it with a potassium chloride solution to obtain a high-purity potassium bicarbonate solution.

[0053] See Figure 1 , for the multi-valent separation electrodialysis system used in the present invention, the initial fresh water chamber is added with the extracted seawater salt concentration of 2 - 3.5%, and pure water is added to the concentrated water. Finally, the fresh water is reduced to 1 - 1.5%, and the concentrated water is increased to 8 - 15%.

[0054] Single-stage multi-valent separation electrodialysis can also be used according to the usage conditions, or a multi-stage multi-valent separation electrodialysis device can be used to concentrate seawater. The single-stage multi-valent ion interception efficiency is 85 - 95%, and the multi-stage interception efficiency can reach 97 - 100%.

[0055] During use, direct current is given to the system. Under the condition of electric drive, the cations in the fresh water chamber migrate towards the negative electrode. When passing through a multi-valent ion exchange membrane, according to its selective permeability to ions, monovalent ions pass through for purification, and multi-valent ions such as magnesium ions and calcium ions are selectively blocked, thereby realizing the refinement and concentration of salt. According to actual needs, through multi-stage system blocking, the required purified monovalent metal ion salt solution is finally obtained.

[0056] For the cation resin column used in the present invention, the resin filled can be selected from one of DOWEX D262, POLY-SPHER 550, Purolite S-960, Zheng Guang, Su Qing 402, Lan Xiao 500 or KeHaiSi CH-93. The content of multi-valent metal ions in the feed is 10 - 30 ppm, the flow rate through the column is 5 - 25 m / h, and the pH is 4 - 10.

[0057] See Figure 2 , the bipolar membrane electrodialysis system used in the present invention successively includes a positive electrode plate, a polar membrane spacer, a polar membrane, a spacer, a bipolar membrane, a spacer, an anion exchange membrane, a spacer, a cation exchange membrane, a spacer, a bipolar membrane, a spacer, an anion exchange membrane,

[0058] a spacer, a cation exchange membrane, a spacer,... a bipolar membrane, a spacer, a cation exchange membrane, a spacer, a polar membrane, a polar membrane spacer and a negative electrode plate; wherein, the bipolar membrane, the anion exchange membrane and the cation exchange membrane together constitute a unit. The bipolar membrane and the anion exchange membrane constitute an acid chamber, the anion exchange membrane and the cation exchange membrane constitute a material chamber, the cation exchange membrane and the bipolar membrane constitute an alkali chamber, and the polar membrane and the electrode plate constitute a polar water chamber. The material chamber is the high-concentration salt solution obtained in step 2), and the polar water chamber is a 2 - 4% alkali solution, which can use sodium hydroxide. The material chamber, the acid chamber, the alkali chamber and the polar water chamber are independent of each other, and the operating temperature is 0 - 35°C. The supporting equipment includes circulating cooling water and a filter.

[0059] During use, direct current is given to the system, and the bipolar membrane can convert H2O into H + and OH -, and are respectively transferred to the cathode side and the anode side of the membrane. Under the condition of electric drive, the monovalent metal cations in the material chamber pass through the cation exchange membrane and combine with the OH⁻ generated on the cathode side of the bipolar membrane to form an alkali; the anions pass through the anion exchange membrane and simultaneously combine with the H⁺ generated on the anode side of the bipolar membrane to form an acid.

[0060] See Figure 3 , the carbon dioxide enrichment device used in the present invention includes a gas pressurization device and a carbon capture membrane module. The carbon capture membrane module includes an air inlet, a permeate outlet, and a retentate outlet. The inlet CO₂ concentration is 0.03 - 30%, the parameter selection range of the gas pressurization device is 30 - 80 bar, and the carbon capture membrane is a polymer membrane. Its membrane manufacturers include: DuPont, Asahi Glass of Japan, Dow Chemical of the United States, Celanese of France, SK Innovation of South Korea, and Nanjing Yangtze River Delta Membrane Technology Research Institute of China.

[0061] The carbon dioxide enrichment device can be composed of a combination of multiple-stage gas pressurization devices and carbon capture membrane modules. For example: a first-stage gas pressurization device, a first-stage carbon capture membrane module, a second-stage gas pressurization device, and a second-stage carbon capture membrane module together constitute the carbon dioxide enrichment device.

[0062] The inlet CO₂ concentration includes 5 - 30%, the enriched CO₂ purity can reach 70 - 95%, and the recovery rate can reach 65 - 90%.

[0063] During use, a gas containing CO₂ is pressurized by the gas pressurization device and then enters the carbon capture membrane module. The selected polymer membrane has selective permeability to CO₂. The gas intercepted except for CO₂ is discharged through the retentate outlet or enters the next-stage carbon capture membrane module, and the permeated CO₂ is collected through the permeate outlet. When the inlet CO₂ concentration is lower than 10%, the permeate can be mixed with the front-end inlet gas and enter the carbon capture membrane module to improve the carbon capture efficiency of the membrane module and increase the captured CO₂ concentration. When the set threshold is reached in this system, it can be introduced into the absorption tower.

[0064] The absorption tower device used in the present invention includes an air inlet, an aeration device, 1 - n series-connected absorption towers, a pH monitoring system, a carbon dioxide monitoring system, and an exhaust outlet.

[0065] During use, the alkali produced in the above step 3) is stored in the absorption tower as the absorbent solution. The CO₂ captured in step (4) is introduced through the air inlet. The aeration equipment can make CO₂ fully contact and react with the absorbent solution to form carbonates or bicarbonates. The operation mode of multiple absorption towers connected in series is adopted to achieve carbon fixation, and the absorption saturation pH is controlled at 7 - 9.

[0066] The desorption tower device used in the present invention includes an acid addition valve, a hydraulic stirring device, a pH monitoring system, a carbon dioxide monitoring system, and an exhaust outlet. The desorbing solution is the acid produced in step (3), and the end pH of complete CO₂ desorption is 3 - 4.

[0067] In use, the rich liquid in the absorption tower is pumped into the desorption tower by a rich liquid pump. According to the amount of CO2 to be desorbed as needed, the acid addition valve is adjusted, and sufficient reaction is carried out through hydraulic stirring. The desorbed pure CO2 is collected and stored, and the brine after desorption can be made into acid and alkali for reuse through step (3).

[0068] The four-compartment displacement electrodialysis device used in the present invention includes: a positive electrode plate, a polar membrane spacer, a polar membrane, a spacer, an anion exchange membrane 1, a spacer, a cation exchange membrane 1, a spacer, an anion exchange membrane 2, a spacer, a cation exchange membrane 2, a spacer, an anion exchange membrane 1, a spacer, a cation exchange membrane 1, a spacer,... an anion exchange membrane 2, a spacer, a cation exchange membrane 2, a spacer, a polar membrane, a polar membrane spacer, and a negative electrode plate; the anion exchange membrane 1, the cation exchange membrane 1, the anion exchange membrane 2, and the cation exchange membrane 2 together form a unit. The anion exchange membrane 1 and the cation exchange membrane 1 form a dilute chamber 1, the cation exchange membrane 1 and the anion exchange membrane 2 form a concentrated chamber 1, the anion exchange membrane 2 and the cation exchange membrane 2 form a dilute chamber 2, the cation exchange membrane 2 and the anion exchange membrane 1 form a concentrated chamber 2, and the polar membrane and the electrode plate form a polar water chamber.

[0069] In use, the rich liquid, i.e., sodium bicarbonate solution, is introduced into the dilute chamber 1, and potassium chloride solution is introduced into the dilute chamber 2. Sodium chloride solution is produced in the concentrated chamber 1, and potassium bicarbonate solution is produced in the concentrated chamber 2.

[0070] Example 1

[0071] See Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 7 , this example provides the capture of CO2 in the gas produced by coal chemical industry by using the above-mentioned membrane method for carbon capture and solidification. The composition of the flue gas is shown in Table 2.

[0072] See Figure 5 and Figure 7 , the system used in this example includes a polyvalent separation electrodialysis system 1, a concentrated brine lift pump 2, a resin tank 3, an impurity removal brine lift pump 4, a bipolar membrane electrodialysis system 5, an absorption tower device 6, a pressurizing device 7, a membrane capture device 8, a desorption pump 9, a rich liquid pump 10, and a desorption tower device 11.

[0073] The concentrated brine lift pump 2 pumps the concentrated brine obtained from a polyvalent separation electrodialysis system 1 into the resin tank 3, and then pumps it into the bipolar membrane electrodialysis system 5 through the impurity removal brine lift pump 4. The obtained alkali solution enters the absorption tower device 6, and the obtained acid solution is pumped into the desorption tower device 11 through the desorption pump 9.

[0074] The gas containing CO2 pressurized by the pressurizing device 7 enters the membrane capture device 8, and the enriched gas enters the absorption tower device 6 to react with the lye. The rich liquid obtained from the reaction is pumped into the desorption tower device 11 by the rich liquid pump 10 and reacts with the acid solution, so that carbon dioxide is released, and high-purity carbon dioxide gas is collected.

[0075] A two-stage multi-valent electrodialysis system is used to concentrate the monovalent metal salts in seawater to produce a 10% mixed salt solution. Design parameters: the partial pressure of one membrane is 0.5V, and the current density is 400 - 600 A / m 2 , and the operating temperature is 0 - 35°C. The cation composition of the concentrated water in the two-stage multi-valent separation electrodialysis is shown in Table 1.

[0076] After the above-mentioned 10% salt solution is treated by resin, 2N acid and 2N base are produced by bipolar membrane electrodialysis. The acid is used as the desorbing liquid, and the base is used as the absorbing liquid. Through first-stage gas pressurization of 80 bar and second-stage gas pressurization of 50 bar, the second-stage carbon capture membrane group captures and purifies CO2 in the atmosphere to 25%. The purity and recovery rate of the product gas CO2 can reach 80% and 78.7% respectively. The above-mentioned produced gas is absorbed by the absorption tower, the pH at the absorption end point is 8.5, and carbonates, bicarbonates, and hydroxides coexist in the system.

[0077] Table 1. Cation composition of concentrated water in two-stage multi-valent separation electrodialysis

[0078]

[0079] Table 2. Flue gas composition

[0080] <![CDATA[N2]]> <![CDATA[CO2]]> <![CDATA[H2O]]> <![CDATA[O2]]> <![CDATA[SO2]]> <![CDATA[NO x > 74％ 16％ 5％ 3.6％ 0.8％ 0.6％

[0081] Example 2

[0082] See Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 6 And Figure 8 , this example provides the capture of CO2 in methanol production by using the above-mentioned membrane-based carbon capture and solidification method. The composition of the coal gasification gas is shown in Table 3.

[0083] See Figure 6 And Figure 8 , the system adopted in this example includes a multi-valent separation electrodialysis system 1, a concentrated brine lift pump 2, a resin tank 3, an impurity-removing brine lift pump 4, a bipolar membrane electrodialysis system 5, an absorption tower device 6, a pressurizing device 7, a membrane capture device 8, a desorption pump 9, a rich liquid pump 10, and a four-compartment displacement electrodialysis system 12.

[0084] The concentrated brine lift pump 2 pumps the concentrated brine obtained from a multi-valent separation electrodialysis system 1 into a resin tank 3, and then pumps it into a bipolar membrane electrodialysis system 5 through an impurity-removing brine lift pump 4. The obtained lye enters an absorption tower device 6.

[0085] The gas containing CO2 pressurized by a pressurizing device 7 enters a membrane capture device 8. The enriched gas enters the absorption tower device 6 to react with the lye. The obtained rich liquid is pumped into a four-compartment displacement electrodialysis system 12 through a rich liquid pump 10 to react with a potassium chloride solution, and high-purity potassium bicarbonate solution is obtained by displacement. Sodium chloride can be recycled to the bipolar membrane electrodialysis system 5.

[0086] A secondary multi-valent electrodialysis system is used to concentrate monovalent metal salts in seawater to produce a 15% mixed salt solution. Design parameters: membrane partial pressure 0.5V per sheet, current density 400 - 600A / m 2 , and the operating temperature is 0 - 35°C.

[0087] After the above-mentioned 15% salt solution is treated by resin, 2N acid and 2N base are produced by bipolar membrane electrodialysis. The acid is used as the desorbing liquid, and the base is used as the absorbing liquid. By pressurizing the gas at 60 bar in the first stage and 30 bar in the second stage, the secondary carbon capture membrane module captures and purifies CO2 in the atmosphere to 40%. The purity and recovery rate of the product gas CO2 can reach 92% and 90% respectively. The above-mentioned produced gas is absorbed by an absorption tower, and the pH at the absorption end is 8. Design parameters of bipolar membrane electrodialysis: 2V per pair, current density 800A / m 2 , and the operating temperature is 0 - 35°C. The rich liquid of the absorption tower is fed into a four-compartment displacement electrodialysis, and the operating temperature is 0 - 35°C. Design parameters of the four-compartment displacement electrodialysis: 1V per pair, current density 400A / m 2 .

[0088] Table 3. Composition of coal gasification gas

[0089] <![CDATA[CO+H2]]> <![CDATA[CO2]]> <![CDATA[CH4]]> <![CDATA[N2]]> 70％ 25％ 3％ 2％

[0090] It can be seen that in the present invention, monovalent sea salt is extracted by multi-valent separation electrodialysis, converted into acid and base by a bipolar membrane, CO2 is captured and purified by a carbon capture membrane module, the produced base is used for absorption, and the produced acid is used for desorption to obtain pure CO2. The desorbed salt solution can be used to produce acid and base again by a bipolar membrane. Each system can meet the in-vivo cycle, realizing carbon capture and zero discharge of wastewater.

[0091] At the same time, the produced rich liquid can also be subjected to displacement electrodialysis with potassium chloride to produce potassium bicarbonate with an application market. The concentrated water 2 sodium chloride after displacement can be recycled to the front-end bipolar membrane system to make acid and base, and product production can be carried out according to requirements. Resources can be recycled to the front-end process.

[0092] The above are only the preferred embodiments of the present invention, and do not impose any formal or substantial limitations on the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as within the protection scope of the present invention. Any slight changes, modifications, and equivalent variations made by those skilled in the art who are familiar with this specialty without departing from the spirit and scope of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any changes, modifications, and evolutions made to the above embodiments based on the substantial technology of the present invention are still within the scope of the technical solutions of the present invention.

Claims

1. A membrane-based carbon capture and solidification method, characterized in that, The method comprises the following steps: 1) Separating and concentrating seawater through a separation electrodialysis system to obtain concentrated water containing high-concentration monovalent ion chloride salts and fresh water containing polyvalent metal ions; 2) passing the concentrated water obtained in step 1) through a cationic resin column; 3) The concentrated water obtained in step 2) is used to prepare acid solution and alkali solution using a bipolar membrane electrodialysis system; 4) Separate carbon dioxide from other gases through an enrichment device to increase the concentration of carbon dioxide; 5) feeding the carbon dioxide enriched in step 4) into an absorption tower device for carbon capture, and using the alkaline solution obtained in step 3) as an absorption liquid to control the ventilation residence time to obtain a rich solution; 6) The rich liquid obtained from the absorption tower device is pumped into the desorption tower device, and the acid solution obtained in step 3) releases carbon dioxide to obtain high-purity carbon dioxide gas; Alternatively, step 6) is replaced by step 7); 7) The rich liquid obtained from the absorption tower device is pumped into the four-compartment displacement electrodialysis, and is replaced with the potassium chloride solution to obtain a high-purity potassium bicarbonate solution.

2. The membrane-based carbon capture and solidification method according to claim 1, wherein In step 1), the separation electrodialysis system is a multivalent separation electrodialysis system; the initial fresh water chamber is added with extracted seawater with a salt concentration of 2-3.5%, and pure water is added to the concentrated water until the final fresh water concentration is reduced to 1-1.5%, and the concentrated water concentration is increased to 8-15%.

3. A membrane-based carbon capture and solidification method according to claim 1, characterized in that, In step 2), the cationic resin column is filled with one of DOWEX D262, POLY-SPHER 550, Purolite S-960, Zhengguang, Suqing 402, Lanxiao 500 or Kehaisi CH-93, the feed polyvalent metal ion content is 10-30 ppm, the column flow rate is 5-25 m / h, and the pH is 4-10.

4. A membrane-based carbon capture and solidification method according to claim 1, characterized in that, In step 3), the bipolar membrane electrodialysis system comprises, in sequence, a positive electrode plate, a polar membrane separator, a polar membrane, a grid, a bipolar membrane, a grid, an anion exchange membrane, a grid, a cation exchange membrane, a grid, a bipolar membrane, a grid, an anion exchange membrane, a grid, a cation exchange membrane, a grid, ... a bipolar membrane, a grid, a cation exchange membrane, a grid, a polar membrane, a polar membrane grid and a negative electrode plate; wherein, the bipolar membrane, the anion exchange membrane and the cation exchange membrane together constitute a unit, the bipolar membrane and the anion exchange membrane constitute an acid chamber, the anion exchange membrane and the cation exchange membrane constitute a material chamber, the cation exchange membrane and the bipolar membrane constitute an alkali chamber, the polar membrane and the polar plate constitute a polar water chamber, the material chamber, the acid chamber, the alkali chamber and the polar water chamber are independent of each other, and the operating temperature is 0-35°C.

5. A membrane-based carbon capture and solidification method according to claim 4, characterized in that The material chamber contains the concentrated water obtained in step 2), and the polar water chamber contains an alkaline solution with a concentration of 2-4%.

6. The membrane-based carbon capture and solidification method according to claim 1, characterized in that, In step 4), the enrichment device includes a gas pressurizing device and a carbon capture membrane group; wherein the carbon capture membrane group includes an air inlet, a permeate outlet and a retained air outlet, the inlet CO2 concentration is 0.03-30%, the gas pressurizing device parameters are 30-80 bar, and the carbon capture membrane is a polymer membrane.

7. A membrane-based carbon capture and solidification method according to claim 6, characterized in that, The intake CO2 concentration is 5-30%.

8. A membrane-based carbon capture and solidification method according to claim 1, characterized in that In step 5), the absorption tower device includes an air inlet, an aeration device, multiple absorption towers connected in series, a pH monitoring system, a carbon dioxide monitoring system and an exhaust port.

9. A membrane-based carbon capture and solidification method according to claim 1, characterized in that In step 6), the desorption tower device includes an acid addition valve, a hydraulic stirring device, a pH monitoring system, a carbon dioxide monitoring system and an exhaust port. The desorbing liquid is the acid liquid obtained in step 3), and the pH at the end point of complete CO2 desorption is 3-4.

10. A membrane-based carbon capture and solidification method according to claim 1, characterized in that, In step 7), the four-compartment displacement electrodialysis device successively includes a positive electrode plate, a polar membrane spacer, a polar membrane, a spacer, an anion exchange membrane 1, a spacer, a cation exchange membrane 1, a spacer, an anion exchange membrane 2, a spacer, a cation exchange membrane 2, a spacer, an anion exchange membrane 1, a spacer, a cation exchange membrane 1, a spacer,... anion exchange membrane 2, a spacer, a cation exchange membrane 2, a spacer, a polar membrane, a polar membrane spacer and a negative electrode plate; among them, the anion exchange membrane 1, the cation exchange membrane 1, the anion exchange membrane 2, and the cation exchange membrane 2 together constitute a unit. The anion exchange membrane 1 and the cation exchange membrane 1 form a dilute chamber 1, the cation exchange membrane 1 and the anion exchange membrane 2 form a concentrated chamber 1, the anion exchange membrane 2 and the cation exchange membrane 2 form a dilute chamber 2, the cation exchange membrane 2 and the anion exchange membrane 1 form a concentrated chamber 2, and the polar membrane and the electrode plate form a polar water chamber.

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