CN-122010355-A - CO based on seawater grading pretreatment and electrochemical coupling2Trapping system and method

CN122010355ACN 122010355 ACN122010355 ACN 122010355ACN-122010355-A

Abstract

The invention discloses a CO 2 capturing system and method based on seawater grading pretreatment and electrochemical coupling. The system comprises a seawater grading pretreatment unit, an electrochemical coupling trapping unit and a CO 2 separation and collection unit. The electrochemical coupling trapping unit adopts a three-compartment structure of anode compartment-middle compartment-cathode compartment, combines a cation exchange membrane and a proton exchange membrane, utilizes protons generated by an anode to migrate to the middle compartment to react with seawater carbonate to generate CO 2 , synchronously realizes cathodic hydrogen evolution and anodic oxygen evolution, and the CO 2 separation and collection unit collects high-purity CO 2 by a membrane separation and vacuum negative pressure technology. The invention solves the problem of in-situ digestion of deep open sea wind power, realizes the cooperative coupling of seawater purification, CO 2 trapping and green hydrogen preparation, reduces the synthesis cost of green fuel, and has remarkable environmental and economic benefits.

Inventors

YANG YAN
WU XIAOJIONG
GE CHUNLIANG
MAO XIAOYU
CHEN BIAO
YU FENGPING
DING DELONG
CHENG LUYING

Assignees

浙江浙能科技环保集团股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260401

Claims (10)

1. A CO 2 capture system based on seawater fractionation pretreatment and electrochemical coupling, comprising: A seawater fractionation pretreatment unit for providing an adapted feedstock for an electrochemical reaction, comprising: The device comprises a triple filter device and a reverse osmosis device, wherein the triple filter device is used for filtering raw seawater step by step, removing suspended matters and retaining carbonate, and an inlet of the reverse osmosis device is connected with an outlet of the triple filter device and is used for carrying out desalination pretreatment on part of the seawater subjected to triple filtration to produce desalinated seawater; The electrochemical coupling trapping unit comprises a middle compartment, a cathode compartment, an anode compartment, a catalyst, a solid electrolyte, a direct current voltage source and a membrane component for separating the compartments, wherein an inlet of the middle compartment is directly connected with an outlet of the triple filtering device and is used for introducing carbonate-rich seawater after triple filtering; The CO 2 separation and collection unit comprises a membrane separation device and a vacuum pump, wherein an inlet of the membrane separation device is communicated with an outlet of the middle compartment and is used for purifying generated CO 2 , and the vacuum pump is connected with an outlet of the membrane separation device and is used for providing negative pressure to collect purified CO 2 .
2. The CO 2 capturing system based on the seawater grading pretreatment and electrochemical coupling, which is disclosed in claim 1, is characterized in that the triple filtering device consists of a coarse filter, a middle filter and a fine filter which are sequentially connected in series, wherein the coarse filter is a cyclone filter with the particle size of 80-120 mu m and is used for removing suspended matters with the particle size of more than or equal to 80 mu m, the middle filter is a cyclone filter with the particle size of 20-40 mu m and is used for removing suspended matters with the particle size of more than or equal to 20 mu m, and the fine filter is a fine filter with the particle size of 3-7 mu m and is used for removing fine particles with the particle size of less than or equal to 7 mu m.
3. The CO 2 capturing system based on the seawater grading pretreatment and electrochemical coupling according to claim 1, wherein the cation exchange membrane allows cations to permeate and intercept anions and gases and prevents cross contamination of a cathode chamber and substances in an intermediate compartment, has high proton conductivity, ensures directional migration of protons generated by an anode to the intermediate compartment, and has the proton conductivity of more than or equal to 0.01S/cm at 25 ℃.
4. The CO 2 capturing system based on the seawater grading pretreatment and electrochemical coupling according to claim 2, wherein the suspended matter content of the seawater treated by the triple filtering device is less than or equal to 1 mg/L, and the carbonate retention rate is more than or equal to 95%.
5. The CO 2 capture system based on seawater fractionation pretreatment and electrochemical coupling as claimed in claim 2, wherein the desalination rate of the reverse osmosis device is not less than 99%.
6. The CO 2 capturing system based on the seawater grading pretreatment and electrochemical coupling according to claim 1, wherein the catalyst comprises a cathode catalyst arranged in a cathode chamber and an anode catalyst arranged in an anode chamber, wherein the cathode catalyst is a platinum-based catalyst or a nickel-based catalyst for promoting hydrogen evolution reaction, and the anode catalyst is an iridium-based catalyst or a ruthenium-based catalyst for promoting oxygen evolution reaction and proton generation.
7. The CO 2 capture system based on seawater fractionation pretreatment and electrochemical coupling according to claim 1, wherein the solid electrolyte is a strong cation exchange resin or inert ceramic particles, and the solid electrolyte is filled in the middle compartment, the cathode compartment and the anode compartment.
8. The CO 2 capturing system based on the seawater grading pretreatment and electrochemical coupling, which is disclosed in claim 1, is characterized in that the membrane separation device adopts a CO 2 selectively permeable membrane which is made of polyimide, polysulfone or ceramic, the retention rate of CO 2 is more than or equal to 98%, and the vacuum pump is a dry screw vacuum pump or a Roots vacuum pump, and the ultimate vacuum degree is less than or equal to 10 Pa.
9. A method of CO 2 capture using the system of any one of claims 1-8, comprising the steps of: s1, seawater grading pretreatment, namely filtering raw seawater sequentially through a triple filtering device, removing suspended matters and simultaneously retaining carbonate, and dividing the filtered seawater into two paths, namely directly conveying the first path to a middle compartment of an electrochemical coupling trapping unit, conveying the second path to a reverse osmosis device for desalination treatment to obtain desalted seawater, and conveying the desalted seawater to a cathode chamber and an anode chamber of the electrochemical coupling trapping unit respectively; S2, electrochemical coupling trapping, namely applying direct-current voltage to a cathode chamber and an anode chamber for electrolysis; Generating oxygen evolution reaction in the anode chamber to generate protons, wherein the protons migrate to the middle compartment through the proton exchange membrane; In the middle compartment, the migrated protons react with bicarbonate in the seawater to generate CO 2 gas; Generating hydrogen gas by hydrogen evolution reaction in the cathode chamber; S3, CO 2 is separated and collected, namely CO 2 -containing gas generated in the middle compartment is introduced into a membrane separation device for purification, and purified CO 2 is collected under negative pressure provided by a vacuum pump.
10. The method according to claim 9, wherein in step S3, the purity of the CO 2 purified by the membrane separation device is not less than 99%, the collection efficiency is not less than 90%, and the collected CO 2 and hydrogen can be synthesized into green fuel in situ.

Description

CO 2 capturing system and method based on seawater grading pretreatment and electrochemical coupling Technical Field The invention belongs to the technical fields of carbon capture and sequestration (CCUS), new energy consumption and seawater comprehensive utilization, and particularly relates to a CO 2 capture system and method based on seawater grading pretreatment and electrochemical coupling, which are particularly suitable for in-situ consumption scenes of deep sea wind power generation. Background Ocean is the largest carbon sink of the earth, storing about 93% of CO 2, eliminating 30% -40% of man-made carbon emissions each year, and is the core for maintaining global carbon balance. However, as the atmospheric CO 2 concentration rises, the acidification initiated by the ocean absorbing excess CO 2 is severely threatening the ocean ecosystem. The traditional carbon trapping technology is mainly aimed at point source emission, and is difficult to be directly applied to wide sea areas. In recent years, electrochemical-based seawater capture CO 2 technology has received attention. The technology utilizes electric energy to drive electrochemical reaction, extracts CO 2 from sea water, can relieve ocean acidification, protect ecology, and can effectively consume intermittent green power such as offshore wind power. Meanwhile, the process can produce hydrogen (H 2) and oxygen (O 2) as byproducts, provides raw materials for preparing green fuels such as methane and methanol, and has both environmental and economic benefits. However, the existing electrochemical seawater capture CO 2 technology faces many challenges in practical applications: (1) Seawater pretreatment is difficult, and seawater contains a large amount of suspended matters (sediment, microorganisms, scraps and the like) and dissolved salts. If the suspended matters are directly introduced into the electrochemical device, the suspended matters can block the electrode, block the flow channel, pollute and even damage the ion exchange membrane, so that the system efficiency is drastically reduced, and the operation and maintenance cost is high. The traditional single filtering mode is difficult to consider the filtering precision and the efficiency. (2) The reaction efficiency is low, the traditional single-chamber or double-chamber electrolytic cell is difficult to realize the efficient directional migration of protons, the generation rate of CO 2 is low, and the products are easy to cross-pollute. (3) The system integration level is low, the existing sea water pretreatment, electrochemical trapping and gas separation units are mostly independent modules, and the lack of integral optimization design leads to huge system volume and high energy consumption, and is difficult to be deployed on a deep-open sea platform with limited space. Therefore, the technical scheme of efficient, stable and economic seawater CO 2 trapping which can adapt to the quality of complex seawater, has high system integration level, can cooperatively produce high-purity hydrogen and CO 2 and is suitable for deep open sea wind power in-situ digestion scenes is urgently needed in the field. Disclosure of Invention Aiming at the problem, the invention provides a CO 2 capturing system and a method based on seawater grading pretreatment and electrochemical coupling, which are used for carrying out grading filtration and efficient CO 2 separation on seawater by constructing a cooperative system of seawater grading pretreatment-electrochemical coupling capturing-CO 2 separation and collection, so as to solve the problems of in-situ digestion of deep and open sea wind power and acidification of seawater and realize the dual targets of carbon reduction and seawater recycling. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: In one aspect, the invention provides a CO 2 capture system based on seawater fractionation pretreatment and electrochemical coupling, comprising: (1) The seawater grading pretreatment unit is used for providing an adaptive raw material for electrochemical reaction and comprises a triple filtration device and a reverse osmosis device, wherein the triple filtration device is used for filtering raw material seawater step by step, removing suspended matters to avoid blockage/corrosion of electrochemical device components and keeping carbonate in the seawater; (2) The electrochemical coupling trapping unit is a system core and comprises a middle compartment, a cathode compartment, an anode compartment, a catalyst, a solid electrolyte, a direct current voltage source and a membrane component for separating the compartments, wherein an inlet of the middle compartment is directly connected with an outlet of the triple filtering device and is used for introducing carbonate-rich seawater after triple filtering; (3) The CO 2 separation and collection unit comprises a membrane separation device and a vacuum pump, wherein a