Electrodialysis and CO2 capture systems

Abstract

To provide an electrodialysis system and a CO2 recovery system which reduce amine loss by electrodialysis, and increase an impurity removal amount and thereby maintain CO2 absorption efficiency of an absorbent.SOLUTION: An electrodialysis system is provided on a CO2 recovery system having an absorption part 10 for making absorbent containing an amine-based compound absorb at least a part of CO2 in a treated gas containing the CO2, and a regeneration part 12 for emitting the CO2 from the absorbent absorbing the CO2 in the absorption part, and includes a primary treatment unit 13 for performing electrodialysis between a treated absorbent 43B as at least a part of the absorbent emitting the CO2 in the regeneration part, and a first concentrated liquid, and discharging the treated absorption liquid as a primary treatment absorption liquid 43C subjected to the electrodialysis, and a secondary treatment unit 14A for subjecting the primary treatment absorption liquid discharged from the primary treatment unit to electrodialysis.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] Embodiments of the present invention relate to electrodialysis systems and CO2 capture systems. [Background technology]

[0002] Efforts to reduce greenhouse gas emissions are accelerating around the world. As a measure to reduce carbon dioxide (CO2) emissions, which have a large greenhouse effect, hydrogen and regenerative energy are being used. Carbon dioxide is expected to play a major role alongside renewable energy. e Capture, Utilization and Storage(CCUS) CCUS captures CO2 emitted from thermal power plants, steel mills, etc., and converts it into carbon dioxide. By utilizing or storing O2, CO2 emissions into the atmosphere are reduced.

[0003] One of the methods for capturing CO2 is a technology called chemical absorption. The CO2-containing exhaust gas discharged from steel mills and other facilities and amino group-containing compounds (hereinafter referred to as amine compounds) The CO2 is absorbed into the absorbing solution by contacting the In a CO2 capture system that uses chemical absorption, for example, exhaust gas is brought into contact with an absorbing solution. The absorption section absorbs the CO2 in the exhaust gas into the absorbing liquid, and the absorbing liquid that has absorbed the CO2 is heated. The regenerated absorbing liquid is then returned to the absorbing section to release CO2. The absorbent is reused by circulating it within the system between the absorption section and the regeneration section.

[0004] However, when absorbing CO2 in exhaust gas, in addition to NOx and SOx in the exhaust gas, carbon sulphide is also Carbonyl, hydrogen cyanide, thiocyanic acid, thiosulfuric acid, and other inorganic acids are present in the absorption liquid. Reacts with amine compounds to form heat stable amine salts (Heat Stable Amine Salts) In addition, when the absorption liquid is heated and regenerated, an impurity called HSAS is generated. In addition, the amine compounds react with heat or oxygen in exhaust gases to decompose, resulting in thermal stability. Amine salts are formed. When impurities such as heat-stable amine salts accumulate, This not only reduces the CO2 absorption efficiency of the absorption liquid, but also causes corrosion of the equipment. It is desirable to remove it from the harvested liquid.

[0005] As such a thermally stable amine salt removal technology, the CO2 recovery system process is A reclaimer is a device that takes part of the absorbing liquid flowing through the process. This equipment removes impurities while retaining the components necessary for the absorbent, and then returns it to the process. One of the reclaimers used in the chemical absorption process is the electrodialysis device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2015-139748 A [Patent Document 2] JP 2018-34126 A [Patent Document 3] International Publication No. 2014 / 077373 Summary of the Invention [Problem to be solved by the invention]

[0007] In the electrodialysis apparatus, for example, an ion exchange membrane is used to perform electrodialysis. Amine compounds (hereafter referred to as amines) permeate the ion exchange membrane, causing loss of amines. In addition, if impurities cannot be completely removed in one electrodialysis, Impurities remain in the absorption liquid, and it is returned to the process in a state where the CO2 absorption efficiency is reduced. do.

[0008] The problem to be solved by the present invention is to reduce the loss of amine due to electrodialysis and increase the amount of impurities removed. The electrodialysis system and CO2 recovery system maintain the CO2 absorption efficiency of the absorption solution by increasing the The objective of the present invention is to provide a collection system. [Means for solving the problem]

[0009] In order to solve the above problems, the electrodialysis system of the embodiment is The system is configured to treat at least a portion of the CO2 in the gas to be treated by treating the gas with an amine compound. An absorption section that absorbs the CO2 in an absorption liquid containing the CO2, and An electrodialysis system provided in a CO2 recovery system having a regeneration unit that releases O2. The absorbent to be treated is at least a part of the absorbent from which CO2 has been released in the regeneration section, and The absorbent is electrodialyzed against a concentrated liquid, and the absorbent is treated as a primary treated absorbent. a primary treatment unit for discharging the primary treatment absorbing liquid; and and a secondary treatment unit for electrodialyzing the [Brief description of the drawings]

[0010] [Figure 1] Schematic diagram of a CO2 capture system according to a first embodiment. [Diagram 2] Schematic diagram of a secondary treatment unit according to a first embodiment. [Diagram 3] Schematic diagram of a modified example of the CO2 capture system according to the first embodiment. [Figure 4] Schematic diagram of a CO2 capture system according to a second embodiment. [Diagram 5] Schematic diagram of a secondary treatment unit according to a second embodiment. [Figure 6] Schematic diagram of a modified example of the CO2 capture system according to the second embodiment. [Figure 7] Schematic diagram of a CO2 capture system according to a third embodiment. [Figure 8] Schematic diagram of a modified example of the CO2 capture system according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment for carrying out the invention will be described.

[0012] (First embodiment) FIG. 1 is a schematic diagram of a CO2 capture system according to a first embodiment. As shown in FIG. The CO2 capture system 1 includes an absorption section 10, a scrubbing section 11A, and a regeneration section 12. In the recovery system 1, CO2 in the exhaust gas (gas to be treated) 41 containing CO2 is absorbed. The absorbent is discharged between the absorption section 10 and the regeneration section 12 (hereinafter referred to as the inside of the system and the outside of the system). The gas to be treated 41 is circulated from the absorption section 10 to the regeneration section 12. The absorption liquid (rich absorption liquid) 42 that has absorbed CO2 is fed from the regeneration section 12 to the absorption section 1. At 0, some or almost all of the CO2 is removed from the rich absorption liquid 42 in the regeneration section 12 and regenerated. The dotted line in the figure indicates the concentrated liquid outside the system. The dashed line indicates the path of the absorbing liquid outside the system.

[0013] The absorption liquid is an amine-based aqueous solution containing an amine compound (hereinafter referred to as an amine) and water. Preferred amines include, for example, monoethanolamine, 2-aminoethanolamine, Primary amines such as 2-methyl-1-propanol, diethanolamine, 2-methyl- Secondary amines such as ethylaminoethanol, triethanolamine, N-methyldiethylamine, Tertiary amines such as ethanolamine, ethylenediamine, triethylenediamine, diamine Polyethylene polyamines such as ethylene triamine, piperazines, piperidines, Cyclic amines such as pyrrolidines, polyamines such as xylylenediamine, methyl and amino acids such as amino carboxylic acids. These may be used alone or in combination. A mixture of two or more species can be used.

[0014] The absorbing liquid is usually used as an aqueous solution containing 10 to 70% by weight of these amines. In addition, the absorption liquid may contain a reaction promoter or other additives to improve the absorption performance of acid gases such as CO2. Nitrogen-containing compounds to prevent corrosion of plant equipment, anticorrosives to prevent foaming, and extinguishers to prevent foaming. Foaming agents, antioxidants to prevent deterioration of the absorption liquid, pH adjusters, and other compounds are added to the absorption Any suitable proportion may be contained within the range that does not impair the effect of the liquid.

[0015] In this embodiment, a part of the lean absorbent 43A is abraded during the supply to the absorbing section 10. The treated absorbent 43B is extracted and fed from the system to the primary treatment unit 13. In the treatment unit 13, impurities in the treated absorbing liquid 43B are removed, and the primary treated absorbing liquid 43C is This primary treatment absorbent 43C is returned to the lean absorbent 43A and mixed lean absorbent 43 E is supplied to the absorption section 10. In this embodiment, the absorption liquid is liquor 43A, treated absorbent 43B, primary treated absorbent 43C, and mixed lean absorbent 43E. This includes:

[0016] A typical example of the gas to be treated 41 is exhaust gas containing CO2, for example, from a thermal power plant. Combustion exhaust gases emitted from boilers and gas turbines, etc., and processes generated in steel plants The gas to be treated 41 is preferably pressurized by a blower or the like and cooled by a cooler. After being cooled by the above, the gas is supplied to the absorption section 10 from the lower part through the treated gas supply line L1. It is possible.

[0017] The absorption section 10 absorbs CO2 in the gas 41 to be treated using a mixed lean absorption gas supplied to the absorption section 10. The cleaning unit 11A cleans the CO2-removed flue gas 44 from which CO2 has been removed. The gas is washed with the cleaning solution 45A, and the absorbing solution entrained in the CO2-removed flue gas 44 is collected.

[0018] Here, the absorption section 10 preferably includes a packing material to increase the gas-liquid contact efficiency. A liquid distributor (not shown) may be provided above the absorption section 10. The lean absorbent 43E is dispersed and falls by the liquid distributor. The gas 41 flows from the lower part to the upper part of the absorbing section 10. When the natural gas 41 comes into contact with the mixed lean absorbing liquid 43E in a counterflow manner, the natural gas 41 is reacted with the mixed lean absorbing liquid 43E in a counterflow manner as represented by the following formula (1), for example: 2) occurs, and the thermally decomposable salt (R3NH2CO3) and the thermally stable amine salt ( R3NHX) is formed, and the CO2 in the gas to be treated 41 is absorbed in the mixed lean absorption liquid 43E. and is removed from the gas 41 to be treated.

[0019] The mixed lean absorbent 43E absorbs the CO2 in the gas 41 to be treated, and is converted into a rich absorbent 42 The rich absorbent 42 is stored in the lower part of the absorbing section 10. Organic acids produced by reactions with oxygen contained in the gas to be treated, SOx, NOx, and sulfur contained in the gas to be treated Carbonyl chloride, hydrogen cyanide, thiocyanic acid, thiosulfuric acid, and other inorganic acids are absorbed. The resulting heat stable amine salt is stored, where R is hydrogen, substituted or unsubstituted amine. The alkyl group may form a heterocycle. R3N+CO2+H2O → R3NH2CO3···(1) R3N+HX → R3NHX (2)

[0020] The CO2-removed flue gas 44 that has risen inside the absorbing section 10 is supplied to the cleaning section 11A. The cleaning unit 11A cleans the CO2-removed flue gas 44 with a cleaning liquid 45A. The amine entrained in the washing section 11A is collected. A liquid disperser (not shown) is provided above the washing section 11A. The cleaning liquid 45A supplied to the cleaning section 11A is dispersed and falls by a liquid disperser. When the CO2-removed exhaust gas 44 ascending in the cleaning section 11A comes into contact with the cleaning liquid 45A, The amine entrained in the CO2 removed flue gas 44 is collected in the washing liquid 45A.

[0021] The cleaning liquid 45A is stored in, for example, a cleaning liquid storage section (not shown) provided below the cleaning section 11A. The cleaning liquid is stored in the cleaning liquid storage section 11A, and the cleaning liquid is circulated by a cleaning liquid circulation line L2 that connects the cleaning liquid storage section 11A to the upper part of the cleaning section 11A. The liquid is then supplied again to the cleaning section 11A.

[0022] The cleaning solution 45A may be returned to the system for operational reasons. At the beginning of the transfer, it is preferable to use pure water, for example. Since it is a basic substance, the cleaning efficiency is higher when it is acidic, so for example, sulfuric acid It is also preferable to use

[0023] The CO2 removed exhaust gas 44 is purified in the cleaning section 11A and then passed through the cleaning section 11A as purified gas 46A. It is discharged from the top of 11A.

[0024] On the other hand, the rich absorbing liquid 42 stored in the lower part of the absorbing section 10 is discharged from the lower part of the absorbing section 10. The rich absorbent supply line L3 is connected to the rich absorbent supply line L3 through the rich absorbent supply line L3. The pressure is increased by a pump (not shown), and the regenerated refrigerant in the regenerator 12 is passed through the heat exchanger 20. After heat exchange with the absorbing liquid 43A, the absorbing liquid is supplied to the regenerating section 12. By exchanging heat between the absorbing liquid 42 and the lean absorbing liquid 43A, the lean absorbing liquid 43A The rich absorbing solution 42 is heated by the rich absorbing solution 42. Conversely, the rich absorbing solution 42 is cooled by the rich absorbing solution 42. The lean absorbing liquid 43A is cooled. The heat exchanger 20 may be a plate heat exchanger, A known heat exchanger such as a shell-and-tube heat exchanger can be used.

[0025] The regeneration unit 12 releases CO2 from the rich absorbing solution 42 to make the rich absorbing solution 42 lean. The rich absorbent 42 is supplied to the regeneration section 12 and regenerated as the absorbent 43A. By heating with steam in a heater (not shown), the C contained in the rich absorption liquid 42 is O2 is desorbed, and some or almost all of the CO2 contained in the rich absorption liquid 42 is removed. The resulting lean absorbent is 43A.

[0026] At this time, the lean absorbing solution 43A generates water vapor and the remaining CO2 is converted into CO2 gas. The CO2 gas is simultaneously evaporated from the lean absorption liquid 43A and released as a gas (not shown). The CO2 gas and the water vapor are discharged to the regeneration section outlet line L4 at the top of the regeneration section 12. The regenerator outlet gas 47 containing water vapor is cooled by cooling water in the cooler 21, and the water vapor is condensed. The condensed water and CO2 gas are mixed in the regenerator outlet gas 47, which is then separated into gas and liquid. The CO2 gas 48 is separated from the condensed water 49 by the separator 22. The condensed water 49 is discharged from the top of the gas-liquid separator 22 to the outside. The condensed water is extracted from the condensed water condensate tank 11 and supplied to the upper part of the regeneration section 12 through a condensed water line L5.

[0027] The lean absorbent 43A stored in the lower part of the regeneration section 12 is The absorbent is discharged from the absorbent discharge line L6 and exchanges heat with the rich absorbent 42 in the heat exchanger 20. The lean absorbing solution 43A is then cooled in a cooler (not shown) and then The same is supplied to section 10.

[0028] An absorbent discharge line branched off from the lean absorbent discharge line L6 and connected to the primary treatment unit 14 A part of the lean absorbent 43A supplied to the absorbing section 10 is discharged through a discharge line L7. The absorbent is then supplied to the primary treatment unit 13 as the primary treatment absorbent 43B. A line L8 is provided, and the primary treatment absorption liquid 43C discharged from the primary treatment unit 13 is The primary treated absorbent is returned to the lean absorbent discharge line L6 through the primary treated absorbent return line L8, and the lean absorbent is discharged from the absorption section 1 The absorbent discharge line L7 is connected to the lean absorbent discharge line L6. The branching position may be either upstream or downstream of the cooler (not shown) in the flow direction of the absorption liquid. stomach.

[0029] The primary treatment unit 13 includes a primary treatment unit 13A, a secondary treatment unit 14A, and a concentrated liquid A concentrated liquid circulation line L9 is provided to connect the concentrated liquid tank 23 to the primary treatment liquid. The concentrated liquid 50A is supplied to the primary treatment unit 13, and the primary treatment liquid discharged from the primary treatment unit 13 is The concentrated solution 50B is supplied to the secondary treatment unit 14A. The secondary treatment concentrate 50C discharged from A is supplied to the concentrate tank 23.

[0030] The concentrated solution 50A may have an electrical resistance that allows electrodialysis, but it may also be used if an acid component is added in advance. If this is done, the amount of amine that has moved to concentrated solution 50A and exists as a cation will increase, The amount of amine recovered is increased, which is more preferable. Examples of the acid component include sulfuric acid, nitric acid, formic acid, and acetic acid. Acid, etc. can be used. In addition, if the concentrated liquid 50A is recycled, Since the acid components removed from 43B accumulate, add the acid components only at the beginning of operation, and then If no acid is added, it will be possible to reduce the amount of acid used.

[0031] When the acid content of the heat-stable amine salt of concentrated solution 50A reaches a specified concentration, discard it and replace it with new solution. It is also possible to continuously extract a portion of the concentrated liquid and supply fresh concentrated liquid. The concentrate is continuously fed and the acid component of the heat-stable amine salt in the concentrate is adjusted to a predetermined concentration. You can drive to.

[0032] The secondary treatment unit 14A is connected to a deionized water tank 24. A deionized water supply line L10 is connected to the secondary treatment unit 14A and the lean absorbent discharge. A secondary treated deionized water return line L11 is provided, which connects to the line L6. From the tank 24, deionized water 51A is supplied to the secondary treatment unit 14A. The secondary treated deionized water 51B discharged from the unit 14A is fed to the lean absorbent discharge line L The secondary treatment unit 14A is supplied to the absorption section 10 through a concentrated liquid circulation loop. Through the inlet L9, the concentrate 50A from the concentrate tank 23 and the concentrate 50B from the primary treatment unit 13 are The primary treated concentrate 50B is supplied from the above.

[0033] The primary treatment unit 13 receives the absorbent 43B to be treated from the absorbent withdrawal line L7 and The concentrated liquid 50A is supplied from the concentrated liquid circulation line L9, and the thermal stability of the absorbent 43B to be treated is improved. The primary treatment unit 13 is, for example, a cathode, an anode, and a cation exchanger. The ion exchange membrane includes an ion exchange membrane, an anion exchange membrane, and a bipolar membrane (all not shown).

[0034] As shown in FIG. 2, the secondary treatment unit 14A includes a cathode 25, an anode 26, and a cation exchanger. The cathode 25 is connected to the anode 26 via a bipolar membrane 27 and a bipolar membrane 28. , the cation exchange membrane 27, the bipolar membrane 28, and the cation exchange membrane 27 are arranged in this order.

[0035] The cation exchange membrane and the cation exchange membrane 27 are configured to pass cations and anions. A polymer membrane with cation exchange groups that can block the passage of cations is used. The exchange membrane 27 may be, for example, a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, or a sulfate ester. A membrane made of a polymer having one or more of a phosphate ester group or a phosphate ester group can be used. Specifically, examples of suitable cation exchange membranes include Neocepta CMX and Neocepta CMB (manufactured by NEOSEPTA CMB Co., Ltd.). Astom Corporation, product name: Selemion CMV, Selemion CMD, Selemion CSO, Selemion Known cation exchange membranes such as Mion CMF (product name, manufactured by AGC Engineering Co., Ltd.) can be used.

[0036] An anion exchange membrane is capable of passing anions and blocking the passage of cations. The anion exchange membrane 28 is, for example, a polymer membrane having an anion exchange group. The strong basic group of the quaternary ammonium group is a primary amino group, a secondary amino group, a tertiary amino group, A membrane made of a polymer having a weakly basic functional group such as a group can be used. Specifically, the anion exchange membrane is Neocepta AMX or Neocepta AHA (Corporation Astom, product name: Selemion AMV, Selemion AMT, Selemion DSV, Selemion Mion ASV, Selemion AHO (product name, manufactured by AGC Engineering Co., Ltd.) Any known anion exchange membrane can be used.

[0037] The bipolar membrane and the bipolar membrane 28 are formed by stacking an anion exchange membrane and a cation exchange membrane. The anode side is an anion exchange membrane and the cathode side is a cation exchange membrane. When a voltage equal to or higher than the theoretical decomposition voltage of water is applied in the presence of water, the water is converted into hydrogen ions. The bipolar membrane can be electrolyzed to hydroxide ions. Use a known bipolar membrane such as NeoSepta BPU (product name, manufactured by Astom Corporation) can be done.

[0038] In the primary treatment unit 13, when a voltage is applied to the cathode and the anode, the absorbent liquid 43 to be treated The anions, which are the acidic components of the heat-stable amine salt in B, are attracted to the anode side and move to the concentrated solution 50A side. By moving the filter, the acidic components of the heat-stable amine salt are removed from the absorbent 43B to be treated.

[0039] The secondary treatment unit 14A is supplied with deionized water 51A from the deionized water tank 24. At the same time, the primary treatment concentrate 50B discharged from the primary treatment unit 13 is supplied to the septic tank 11. Here, the deionized water 51A and the primary treatment concentrate 50B are passed through a cation exchange membrane 27 and a buffer. In the region partitioned by the bipolar membrane 28, the electrodes are alternately arranged in this order from the cathode 25 to the anode 26. The device is supplied to be placed in a position such that

[0040] The secondary treatment unit 14A is supplied with concentrated liquid 50A from a concentrated liquid tank 23. Alternatively, the concentrated liquid may be supplied from a separate concentrated liquid tank (not shown). By using the tank, the type and concentration of the concentrated liquid will be different from that of concentrated liquid 50A. can be done.

[0041] In the secondary treatment unit 14A, when a voltage is applied to the cathode 25 and the anode 26, the concentrated liquid The amine cations in 50A and the primary treatment concentrate 50B are attracted to the cathode 25, The concentrated solution 50A and the first-processed concentrated solution 50B are mixed with the ionized water 51A. In unit 13, amines that have migrated from the absorbent 43B to the concentrated liquid 50A are included. Therefore, in the secondary treatment unit 14A, the concentrated liquid 50A and the primary treatment concentrated liquid 5 The amine in 0B is recovered by moving to the deionized water 51A side.

[0042] The secondary treatment concentrate 50C from which the amines have been removed in the secondary treatment unit 14A is circulated as a concentrate. The amine is recovered from the secondary treatment deionization process and fed to the concentrate tank 23 through the loop line L9. The lean water 51B is supplied to the absorbing section 10 through a lean absorbent discharge line L6.

[0043] In addition, a higher voltage is applied to the secondary treatment unit 14A than to the primary treatment unit 13. This allows recovery of amines from the primary treatment concentrate 50B, which has a relatively low amine concentration. It can be collected.

[0044] In addition, the primary treatment unit 13 is provided with a device for adjusting the conductivity of the absorbent 43B or the concentrated liquid 50A. The secondary treatment unit 14A may be provided with a conductivity measuring section (not shown) for measuring the conductivity. A conductivity measuring unit (not shown) for measuring the conductivity of the treated concentrated liquid 50B may be provided. Based on the measured electrical conductivity, the absorbed liquid 43B to be treated, the concentrated liquid 50A, or the primary treated concentrated liquid 50B is selected. Alternatively, the supply of the power may be controlled.

[0045] In this manner, according to the present embodiment, a part of the lean absorbent 43A is treated as the absorbent 43B. The suction gas is then extracted and fed to the primary treatment unit 13. The acidic components in the collected liquid 43B are removed by transferring them to the concentrated liquid 50A. The primary treatment concentrate 50B discharged from the primary treatment unit 13 is fed to the secondary treatment unit 1 In the secondary treatment unit 14A, the concentrate 50A and the primary treatment concentrate 50 are fed to the secondary treatment unit 14B. The amine in B is recovered by transfer into deionized water 51A.

[0046] By adopting such a configuration, the ammonia transferred to the concentrated liquid 50A in the primary treatment unit 13 is The amines can be recovered in the secondary treatment unit 14A. This reduces the amine loss in system 1, thereby maintaining the CO2 capture efficiency. can be done.

[0047] As a modification of the CO2 capture system 1 according to this embodiment, as shown in FIG. The auxiliary cleaning section 11B is further provided downstream in the flow direction of the cleaning section 11A, and the concentrated liquid circulation line The pipe L9 may be connected to the auxiliary washing section 11B. The concentrate 50A or the secondary treatment concentrate The liquid 50C is supplied to the auxiliary cleaning section 11B as the cleaning liquid 45B, and the cleaning liquid 50C is supplied to the auxiliary cleaning section 11B from the cleaning section 11A. The purified gas 46A supplied to the 11B is further washed with the washing liquid 45B. The purified gas 46B is discharged from the upper part of the auxiliary cleaning section 11B. The auxiliary cleaning section 11B is configured as follows: , may be the same as the cleaning section 11A.

[0048] The concentrated liquid circulation line L9 is connected to the cleaning section 11A, and the concentrated liquid 50A and the primary treatment concentrated liquid 50B or the secondary treatment concentrate 50C may be supplied to the cleaning section 11A as the cleaning liquid 45B. .

[0049] By adopting such a configuration, in addition to the effect of this embodiment, the auxiliary cleaning section 11B The amines entrained in the purified gas 46A are then collected by the cleaning liquid 45B. The amine loss in the CO2 capture system 1 can be reduced, so the CO2 capture efficiency can be maintained. It is possible.

[0050] Second embodiment FIG. 4 is a schematic diagram of a CO2 capture system according to the second embodiment. The same reference numerals are used for the same parts, and detailed explanations are omitted. The difference is in the configuration of the secondary processing unit 14B.

[0051] In this embodiment, a part of the lean absorbent 43A is mixed with the absorbent to be treated while being supplied to the absorbing section 10. The collected liquid is extracted as collected liquid 43B and is supplied to the primary treatment unit 13 from the system. In the unit 13, impurities in the treated absorbing liquid 43B are removed, and the treated absorbing liquid becomes a primary treated absorbing liquid 43C. A part of this primary treatment absorbing liquid 43C is treated as the primary treatment absorbing liquid in the secondary treatment unit 14B described later. Impurities are further removed from the collected liquid 43C, which is then returned to the system as the secondary treatment absorbent 43D. The absorbent 43A is mixed with the primary treatment absorbent 43C and the secondary treatment absorbent 43D to form a mixed leach. The absorbent is supplied to the absorbing section 10 as the absorbing liquid 43E. Lean absorbent 43A, treated absorbent 43B, primary treated absorbent 43C, secondary treated absorbent 4 3D, and mixed lean absorbent 43E.

[0052] As shown in FIG. 4, the CO2 capture system 1 according to this embodiment includes a lean absorbent discharge line. An absorbent extraction line L7 is provided which branches off from the inlet L6 and is connected to the primary treatment unit 14. A part of the lean absorbing liquid 43A supplied to the absorbing section 10 is treated as the absorbing liquid 43B. , which are supplied to the primary processing unit 13.

[0053] In addition, a primary treatment absorbing liquid supply system is provided to connect the primary treatment unit 13 and the secondary treatment unit 14B. A supply line L12 is provided, and the primary treatment absorbent 43C discharged from the primary treatment unit 13 is A part of the absorbent is supplied to the secondary treatment unit 14B through the primary treatment absorbent supply line L12. The other part passes through the primary treatment absorbent return line L8 to the lean absorbent discharge line L6. The lean absorbent is then returned to the absorber 10 and fed to the secondary treatment unit 14B. A secondary treatment absorbent return line L13 is provided to connect the line L6 to the secondary treatment unit. The secondary treatment absorbent 43D discharged from 14B passes through the secondary treatment absorbent return line L13. The absorbent is discharged from the line L7, which is connected to the line L6 for drawing out the lean absorbent. The position where the absorbent discharge line L6 branches off is the same as the position of the cooler (not shown) in the flow direction of the absorbent. ) may be located either upstream or downstream.

[0054] The primary treatment unit 13 includes a primary treatment unit 13B, a secondary treatment unit 14B, and a concentrated liquid A concentrated liquid circulation line L9 is provided to connect the concentrated liquid tank 23 to the primary treatment liquid. The concentrated liquid 50A is supplied to the primary treatment unit 13, and the primary treatment liquid discharged from the primary treatment unit 13 is The concentrated solution 50B is supplied to the concentrated solution tank 23. The concentrated solution tank 23 is then fed to the secondary treatment The concentrated liquid 50A is supplied to the secondary treatment unit 14B, and the secondary treatment unit 14B discharges the concentrated liquid 50A. The post-treatment concentrate 50C is supplied to the concentrate tank 23.

[0055] The secondary treatment unit 14B is connected to the primary treatment unit 13. A primary treatment absorbent supply line L12 and a secondary treatment unit 14B and a lean absorbent A secondary treatment absorbing liquid return line L13 is provided, which connects to the discharge line L6. From the unit 13, a part of the primary treatment absorbing liquid 43C is supplied to the secondary treatment unit 14B. The secondary treatment absorbent 43D discharged from the secondary treatment unit 14B is discharged through the lean absorbent discharge line. The mixed lean absorbent 43E is supplied to the absorption section 10 through the inlet L6. The treatment unit 14B receives the concentrated liquid from the concentrated liquid tank 23 through a concentrated liquid circulation line L9. 50A is supplied.

[0056] As shown in FIG. 5, the secondary treatment unit 14B includes a cathode 25, an anode 26, and a bipolar The cathode 25 is connected to the anode 26 via a membrane 28 and an anion exchange membrane 29. , anion exchange membrane 29, bipolar membrane 28, and anion exchange membrane 29 are arranged in this order.

[0057] The anion exchange membrane 29 is capable of passing anions and blocking the passage of cations. A polymer membrane having an anion exchange group is used. For example, the strong basic group of the quaternary ammonium group is a primary amino group, a secondary amino group, a tertiary ammonium group, A membrane made of a polymer having a weakly basic functional group such as an amino group can be used. Specifically, the new anion exchange membranes are Neocepta AMX and Neocepta AHA (Stock Astom Co., Ltd., product name); Selemion AMV, Selemion AMT, Selemion DSV, Selemion ASV, Selemion AHO (product name, manufactured by AGC Engineering Co., Ltd.) Any known anion exchange membrane can be used.

[0058] In the primary treatment unit 13, when a voltage is applied to the cathode and the anode, the absorbent liquid 43 to be treated The anions, which are the acidic components of the heat-stable amine salt in B, are attracted to the anode side and move to the concentrated solution 50A side. By moving the filter, the acidic components of the heat-stable amine salt are removed from the absorbent 43B to be treated.

[0059] The secondary treatment unit 14B receives the primary treatment absorption liquid 4 discharged from the primary treatment unit 13. 3C is supplied, and concentrated liquid 50A is supplied from the concentrated liquid tank 23. The primary treatment absorption liquid 43C and the concentrated liquid 50A are passed through the bipolar membrane 28 and the anion exchange membrane 2 9, the electrodes are arranged alternately from the cathode 25 to the anode 26 in this order. are supplied to.

[0060] In the secondary treatment unit 14B, when a voltage is applied to the cathode 25 and the anode 26, The anions, which are the acidic components of the heat-stable amine salts in the absorbent 43C, are attracted to the anode 26 and concentrated. The primary treatment absorbent 43C is the absorbent that has been removed in the primary treatment unit 13. Therefore, in the secondary treatment unit 14B, The anions, which are the acidic components of the heat-stable amine salts in the primary treatment absorption liquid 43C, are transferred to the concentrated liquid 50A. Remove it by moving it.

[0061] The secondary treatment absorbent 43D from which the acidic components have been removed in the secondary treatment unit 14B is The secondary treatment concentrate from which the acidic components have been recovered is supplied to the absorption section 10 through the collected liquid discharge line L6. The concentrate 50C is supplied to the concentrate tank 23 through the concentrate circulation line L9.

[0062] In addition, a higher voltage is applied to the secondary treatment unit 14B than to the primary treatment unit 13. This will remove the acidity from the primary treatment absorbent 43C, which has a relatively low acidity concentration. It can be removed.

[0063] In addition, the primary treatment unit 13 is provided with a device for adjusting the conductivity of the absorbent 43B or the concentrated liquid 50A. The secondary treatment unit 14B may be provided with a conductivity measuring section (not shown) for measuring the conductivity. A conductivity measuring unit (not shown) is provided for measuring the conductivity of the treated absorbent 43C or the concentrated liquid 50A. Based on the measured conductivity, the absorbed liquid 43B to be treated, the concentrated liquid 50A, or one of the The system may be configured to control whether or not the subsequently treated absorbing liquid 43C is supplied.

[0064] In this manner, according to the present embodiment, a part of the lean absorbent 43A is treated as the absorbent 43B. The suction gas is then extracted and fed to the primary treatment unit 13. The acidic components in the collected liquid 43B are removed by transferring them to the concentrated liquid 50A. The primary treatment absorbing liquid 43C discharged from the primary treatment unit 13 is fed to the secondary treatment unit 1 In the secondary treatment unit 14B, the acidic content in the primary treatment absorption liquid 43C is converted into concentrated The liquid is removed by transferring it to the shrinkage liquid 50A.

[0065] By adopting such a configuration, the primary treatment unit 13 cannot remove the primary treatment The acidic components in the absorbing solution 43C can be removed in the secondary treatment unit 14B. This increases the amount of impurities removed in the CO2 capture system 1. Recovery efficiency can be maintained.

[0066] As a modification of the CO2 capture system 1 according to this embodiment, as shown in FIG. The auxiliary cleaning section 11B is further provided downstream in the flow direction of the cleaning section 11A, and the concentrated liquid circulation line The pipe L9 may be connected to the auxiliary cleaning section 11B. 0B, or the secondary treatment concentrated liquid 50C is supplied to the auxiliary washing section 11B as the washing liquid 45B, The purified gas 46A supplied from the purification section 11A to the auxiliary cleaning section 11B is purified by the cleaning liquid 45B. The cleaned purge gas 46B is discharged from the upper part of the auxiliary cleaning section 11B. The configuration of the auxiliary cleaning section 11B may be similar to that of the cleaning section 11A.

[0067] The concentrated liquid circulation line L9 is connected to the cleaning section 11A, and the concentrated liquid 50A and the primary treatment concentrated liquid 50B, or the secondary treatment concentrated liquid 50C may be supplied to the washing section 11A as the washing liquid 45B. stomach.

[0068] By adopting such a configuration, in addition to the effect of this embodiment, the auxiliary cleaning section 11B The amines entrained in the purified gas 46A are then collected by the cleaning liquid 45B. Since the amine loss in the CO2 capture system 1 can be reduced, the CO2 capture efficiency can be maintained. can be done.

[0069] Third embodiment 7 is a schematic diagram of a CO2 capture system according to a third embodiment. The same parts are denoted by the same reference numerals, and detailed explanations are omitted. The main difference from the above embodiment is that the present embodiment includes a secondary processing unit 14A and a secondary processing unit 14B. And so.

[0070] In this embodiment, a part of the lean absorbent 43A is mixed with the absorbent to be treated while being supplied to the absorbing section 10. The collected liquid is extracted as collected liquid 43B and is supplied to the primary treatment unit 13 from the system. In the unit 13, impurities in the treated absorbing liquid 43B are removed, and the treated absorbing liquid becomes a primary treated absorbing liquid 43C. A part of this primary treatment absorbing liquid 43C is treated as the primary treatment absorbing liquid in the secondary treatment unit 14B described later. Impurities are further removed from the collected liquid 43C, which is then returned to the system as the secondary treatment absorbent 43D. The absorbent 43A, the primary treatment absorbent 43C, and the secondary treatment absorbent 43D are mixed together to form a mixed liquid. The absorbent is supplied to the absorbent section 10 as the absorbent 43E. These are lean absorbent 43A, treated absorbent 43B, primary treated absorbent 43C, secondary treated absorbent 43D, and mixed lean absorbent 43E.

[0071] As shown in FIG. 7, the CO2 capture system 1 according to this embodiment includes a lean absorbent discharge line. An absorbent extraction line L7 is provided which branches off from the inlet L6 and is connected to the primary treatment unit 14. A part of the lean absorbing liquid 43A supplied to the absorbing section 10 is treated as the absorbing liquid 43B. , which are supplied to the primary processing unit 13.

[0072] In addition, a primary treatment absorbing liquid supply system is provided to connect the primary treatment unit 13 and the secondary treatment unit 14B. A supply line L12 is provided, and the primary treatment absorbent 43C discharged from the primary treatment unit 13 is A portion of the absorbent is supplied to the secondary treatment unit 14B through the primary treatment absorbent supply line 12. The other part is returned to the lean absorbent discharge line L6 through the primary treatment absorbent return line L8. The secondary treatment unit 14B and the lean absorbent discharge line are connected to the absorption section 10. A secondary treatment absorbent return line L13 is provided to connect the secondary treatment unit 1 The secondary treatment absorbent 43D discharged from 4B passes through the secondary treatment absorbent return line L13. The lean absorbent is supplied to the lean absorbent discharge line L6. The position where the absorbent discharge line L6 branches off is a cooler (not shown) in the flow direction of the absorbent. It may be on the upstream side or downstream side of the

[0073] The primary processing unit 13 includes a primary processing unit 13A, a secondary processing unit 14A, and a secondary processing unit 14B. A concentrated liquid circulation line L9 is provided to connect the treatment unit 14B and the concentrated liquid tank 23. The concentrated liquid 50A is supplied from the concentrated liquid tank 23 to the primary treatment unit 13. The primary treatment concentrate 50B discharged from 13 is supplied to the secondary treatment unit 14A. The secondary treatment concentrate 50C discharged from the secondary treatment unit 14A is stored in the concentrate tank 23. Then, the concentrated liquid 50A is supplied from the concentrated liquid tank 23 to the secondary treatment unit 14B. The secondary treatment concentrate 50C discharged from the secondary treatment unit 14B is fed to the concentrate tank 2 3.

[0074] The secondary treatment unit 14A is connected to a deionized water tank 24. A deionized water supply line L10 is connected to the secondary treatment unit 14A and the lean absorbent discharge. A secondary treated deionized water return line L11 is provided, which connects to the line L6. From the tank 24, deionized water 51A is supplied to the secondary treatment unit 14A. The secondary treated deionized water 51B discharged from the unit 14A is fed to the lean absorbent discharge line L The secondary treatment unit 14A is supplied to the absorption section 10 through a concentrated liquid circulation loop. Through the inlet L9, the concentrate 50A from the concentrate tank 23 and the concentrate 50B from the primary treatment unit 13 are The primary treated concentrate 50B is supplied from the above.

[0075] The secondary treatment unit 14B is connected to the primary treatment unit 13. A primary treatment absorbent supply line L12 and a secondary treatment unit 14B and a lean absorbent A secondary treatment absorbing liquid return line L13 is provided, which connects to the discharge line L6. From the unit 13, a part of the primary treatment absorbing liquid 43C is supplied to the secondary treatment unit 14B. The secondary treatment absorbent 43D discharged from the secondary treatment unit 14B is discharged through the lean absorbent discharge line. The mixed lean absorbent 43E is supplied to the absorption section 10 through the inlet L6. The treatment unit 14B receives the concentrated liquid from the concentrated liquid tank 23 through a concentrated liquid circulation line L9. 50A is supplied.

[0076] The secondary treatment concentrate 50C from which the amines have been removed in the secondary treatment unit 14A is circulated as a concentrate. The amine is recovered from the secondary treatment deionization process and fed to the concentrate tank 23 through the loop line L9. The lean water 51B is supplied to the absorbing section 10 through a lean absorbent discharge line L6.

[0077] The secondary treatment absorbent 43D from which the acidic components have been removed in the secondary treatment unit 14B is The secondary treatment concentrate from which the acidic components have been recovered is supplied to the absorption section 10 through the collected liquid discharge line L6. The concentrate 50C is supplied to the concentrate tank 23 through the concentrate circulation line L9.

[0078] In addition, a higher voltage is applied to the secondary treatment unit 14A than to the primary treatment unit 13. This allows recovery of amines from the primary treatment concentrate 50B, which has a relatively low amine concentration. It can be collected.

[0079] In addition, a higher voltage is applied to the secondary treatment unit 14B than to the primary treatment unit 13. This will remove the acidity from the primary treatment absorbent 43C, which has a relatively low acidity concentration. It can be removed.

[0080] In addition, the primary treatment unit 13 is provided with a device for adjusting the conductivity of the absorbent 43B or the concentrated liquid 50A. The secondary treatment unit 14A may be provided with a conductivity measuring section (not shown) for measuring the conductivity. A conductivity measuring unit (not shown) for measuring the conductivity of the treated concentrated liquid 50B may be provided. The treatment unit 14B includes a conductive pipe for measuring the conductivity of the primary treatment absorption liquid 43C or the concentrated liquid 50A. Based on the measured conductivity, the absorbed liquid 43 to be treated is B, concentrated liquid 50A, primary treated concentrated liquid 50B, or primary treated absorbent liquid 43C is supplied. It may be configured to control the same.

[0081] In this manner, according to the present embodiment, a part of the lean absorbent 43A is treated as the absorbent 43B. The suction gas is then extracted and fed to the primary treatment unit 13. The acidic components in the collected liquid 43B are removed by transferring them to the concentrated liquid 50A. The primary treatment concentrate 50B discharged from the primary treatment unit 13 is fed to the secondary treatment unit 1 In the secondary treatment unit 14A, the concentrate 50A and the primary treatment concentrate 50 are fed to the secondary treatment unit 14B. The amine in B is recovered by transfer into deionized water 51A.

[0082] In addition, the concentrated liquid 50A and the primary treatment absorption liquid 43C discharged from the primary treatment unit 13 The secondary treatment unit 14B supplies the primary treatment absorbent 4 The acidic components in 3C are removed by transferring them to concentrated solution 50A.

[0083] By adopting such a configuration, the ammonia transferred to the concentrated liquid 50A in the primary treatment unit 13 is The amine can be recovered in the secondary treatment unit 14A. The acidic components in the primary treatment absorbent 43C that could not be removed by the secondary treatment unit 14B are removed by the secondary treatment unit 14B. Therefore, reducing the amine loss in the CO2 capture system 1 In addition, the amount of impurities removed can be increased, so the CO2 capture efficiency can be maintained. This can be done.

[0084] As a modification of the CO2 capture system 1 according to this embodiment, as shown in FIG. The auxiliary cleaning section 11B is further provided downstream in the flow direction of the cleaning section 11A, and the concentrated liquid circulation line The pipe L9 may be connected to the auxiliary cleaning section 11B. 0B, or the secondary treatment concentrated liquid 50C is supplied to the auxiliary washing section 11B as the washing liquid 45B, The purified gas 46A supplied from the purification section 11A to the auxiliary cleaning section 11B is purified by the cleaning liquid 45B. The cleaned purge gas 46B is discharged from the upper part of the auxiliary cleaning section 11B. The configuration of the auxiliary cleaning section 11B may be similar to that of the cleaning section 11A.

[0085] The concentrated liquid circulation line L9 is connected to the cleaning section 11A, and the concentrated liquid 50A and the primary treatment concentrated liquid 50B, or the secondary treatment concentrated liquid 50C may be supplied to the washing section 11A as the washing liquid 45B. stomach.

[0086] By adopting such a configuration, in addition to the effect of this embodiment, the auxiliary cleaning section 11B The amines entrained in the purified gas 46A are then collected by the cleaning liquid 45B. The amine loss in the CO2 capture system 1 can be reduced, so the CO2 capture efficiency can be maintained. It is possible.

[0087] Although several embodiments of the present invention have been described above, these embodiments are presented as examples. These novel embodiments are provided for illustrative purposes only and are not intended to limit the scope of the invention. , and can be implemented in various other forms, without departing from the spirit of the invention. Various omissions, substitutions, and modifications can be made. The scope of the invention and its equivalents as described in the claims are included in the scope and spirit of the disclosure. Included in. [Explanation of symbols]

[0088] 1: CO2 capture system, 10: absorption section, 11A: cleaning section, 11B: auxiliary cleaning section, 12: Regeneration section, 13: primary treatment unit, 14A, 14B: secondary treatment unit, 20: heat exchanger , 21: cooler, 22: gas-liquid separator, 23: concentrated liquid tank, 24: deionized water tank, 2 5: cathode, 26: anode, 27: cation exchange membrane, 28: bipolar membrane, 29: anion exchange membrane Membrane, 41: gas to be treated, 42: rich absorbing liquid, 43A: lean absorbing liquid, 43B: gas to be treated Absorbent, 43C: Primary treatment absorbent, 43D: Secondary treatment absorbent, 43E: Mixed lean absorbent , 44: CO2 removal exhaust gas, 45A, 45B: cleaning liquid, 46A, 45B: purified gas, 47 : Regeneration section outlet gas, 48: CO2 gas, 49: Concentrated water, 50A: Concentrated liquid, 50B: Primary treatment 50C: Secondary treatment concentrate, 51A: Deionized water, 51B: Secondary treatment deionized water L1: treated gas supply line, L2: cleaning liquid circulation line, L3: rich absorbing liquid supply line L1: Regeneration unit outlet line, L2: Condensate line, L3: Lean absorbent discharge line, L4: Regeneration unit outlet line, L5: Condensate line, L6: Lean absorbent discharge line, L 7: Absorbent extraction line, L8: Primary treatment absorbent return line, L9: Concentrated liquid circulation line L10: deionized water supply line, L11: secondary treated deionized water return line, L12: Secondary treatment absorbent supply line, L13: Secondary treatment absorbent return line.

Claims

1. CO ２ At least a part of the CO in the gas to be treated ２ an absorbing section for absorbing the CO ２ The CO ２ and a regeneration unit that releases CO ２ An electrodialysis system provided in a recovery system, The regeneration unit ２ a primary treatment unit which performs electrodialysis between a treated absorption liquid, which is at least a part of the absorption liquid from which the above-mentioned has been released, and a first concentrated liquid, and discharges the treated absorption liquid as an electrodialyzed primary-treated absorption liquid; a secondary treatment unit for electrodialyzing the primary treatment absorption liquid discharged from the primary treatment unit; Equipped with the secondary treatment unit comprises an anion exchange membrane; an electrodialysis system for removing acidic components in the primary treated absorbent by performing electrodialysis between the primary treated absorbent and a second concentrated liquid;

2. 2. The electrodialysis system according to claim 1, wherein the first concentrate used in the primary treatment unit and the second concentrate used in the secondary treatment unit contain an acid component and have different concentrations of the acid component.

3. CO ２ At least a part of the CO in the gas to be treated ２ an absorbing section for absorbing the CO ２ The CO ２ and a regeneration unit that releases CO ２ An electrodialysis system provided in a recovery system, The regeneration unit ２ a primary treatment unit which performs electrodialysis between a treatment liquid, which is at least a part of the absorption liquid from which the aforesaid absorbent has been released, and a first concentrate, and discharges the first concentrate as an electrodialyzed primary treatment concentrate; a secondary treatment unit for electrodialyzing the primary treatment concentrate discharged from the primary treatment unit; Equipped with the secondary treatment unit comprises a cation exchange membrane; an electrodialysis system for recovering amines in the primary treatment concentrate by electrodialysis between the primary treatment concentrate and deionized water;

4. The primary processing unit includes: A bipolar membrane; An anion exchange membrane; A cation exchange membrane; 4. The electrodialysis system according to claim 1, further comprising a first concentrate for transferring acidic components in the absorption liquid to be treated to the first concentrate for removal.

5. The primary processing unit includes: The electrodialysis system according to claim 1 or 3, further comprising a first conductivity measuring unit for measuring the conductivity of the absorption liquid to be treated or the first concentrated liquid.

6. The secondary processing unit includes: The electrodialysis system according to claim 1 or 3, further comprising a second conductivity measuring unit for measuring the conductivity of the first treatment absorption liquid or the first treatment concentrated liquid.

7. 2. The electrodialysis system according to claim 1, wherein the concentrated liquid is an aqueous solution containing an acidic component.

8. 4. The electrodialysis system according to claim 1, wherein a higher voltage is applied to the secondary treatment unit than to the primary treatment unit.

9. CO ２ At least a part of the CO in the gas to be treated ２ an absorbing section for absorbing the above-mentioned in an absorbing liquid containing an amine compound; The CO ２ The CO ２ A regenerating unit that releases the The electrodialysis system according to claim 1 or 3, In the regeneration section, ２ At least a portion of the absorption liquid from which CO has been released is supplied to the electrodialysis system. ２ Collection system.

10. CO discharged from the absorption section ２ Further comprising a cleaning unit for cleaning the removed exhaust gas, 10. The CO purifying apparatus according to claim 9, wherein at least a portion of the concentrated liquid discharged from the electrodialysis system is supplied to the cleaning section. ２ Collection system.

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