Device system and method for capturing CO2 in flue gas difficult to treat and coupling with synthesis of green chemicals

Abstract

The invention provides a device system and method for coupling CO2 capture of flue gas difficult to treat with green chemical synthesis. The device system comprises a first CO2 capture device, a first electrolytic cell, a second CO2 capture device, a heat exchange device, a second electrolytic cell and a green chemical synthesis device which are arranged in series, and the heat exchange device is circularly connected with the first CO2 trapping device through a heat exchange pipeline. The device system provided by the invention is provided with two sets of CO2 trapping devices and the electrolytic bath in series connection, so that efficient recycling of the trapped CO2 is realized while carbon trapping of various flue gases difficult to treat is achieved, and the device system is suitable for large-scale popularization and application.

Description

Device system and method for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, and more particularly to an apparatus system and method for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals. Background Technology

[0002] Monocyclic aromatic hydrocarbons (such as benzene and xylene) are important chemical products, mainly derived from coal and petroleum.

[0003] Considering the shortage of monocyclic aromatic hydrocarbon feedstocks, using carbon capture technology to capture green carbon dioxide from difficult-to-treat flue gas and coupling it with renewable energy-based hydrogen production to produce high-value-added green chemicals has a dual carbon reduction effect and has been recognized as the mainstream direction for the future, such as carbon dioxide hydrogenation to produce aromatics, methanol, olefins, etc.

[0004] CN117819550A discloses a carbon dioxide capture method. This method includes: spraying an alkaline solution through a spray structure to allow the alkaline solution flowing out of the spray structure to chemically react with carbon dioxide gas in the gas, thereby absorbing the carbon dioxide gas; buffering the solution after the chemical reaction with the carbon dioxide gas through a buffer structure, with the buffered solution flowing out through the spray structure; real-time monitoring of the hydroxide and / or carbonate concentrations in the solution within the buffer structure, and replenishing the buffer structure with alkaline solution or water according to the hydroxide and carbonate concentrations; if the detected hydroxide concentration is less than or equal to m and the carbonate concentration is n, controlling the circulation pump to stop operating, so that the solution buffered in the buffer structure enters an electrolysis device for electrolysis.

[0005] CN118615834A discloses a carbon dioxide capture and utilization system and a carbon dioxide capture and utilization method. The carbon dioxide capture and utilization system includes: an absorption tower with an inlet at the bottom, a liquid inlet at the top, an outlet at the top, and a liquid outlet at the bottom; the inlet is used to receive a carbon-containing mixed gas with a pressure of 0.3-5.0 MPa; the carbon-containing mixed gas includes carbon dioxide and other gases; the liquid inlet is used to receive water; the outlet is used to output water, and the water flows from top to bottom within the absorption tower; a pressure reducing and separation mechanism is located downstream of the outlet to receive carbon dioxide-rich water and to reduce and separate the carbon-rich water; a pressure reducing mechanism is located downstream of the pressure reducing and separation mechanism to reduce the pressure of the carbon-rich water; and a stripping tower, the upper part of which is connected to the pressure reducing mechanism to receive the depressurized carbon-rich water; the gas phase in the stripping tower is hydrogen, the liquid phase is water, and the top of the stripping tower is an outlet for outputting a mixture of hydrogen and carbon dioxide.

[0006] CN117797605A discloses a flue gas carbon dioxide capture system, the system comprising: a carbon dioxide capture tower for capturing carbon dioxide from flue gas; a lean-rich liquid heat exchanger for performing secondary heating of the rich liquid after carbon dioxide absorption; a regeneration tower for performing carbon dioxide desorption from the rich liquid to obtain carbon dioxide-containing regeneration gas and lean liquid; a steam compressor for performing heat exchange between the regeneration gas and condensate; and a boiler for separating condensate and carbon dioxide from the regeneration gas after heat exchange and sending the carbon dioxide to a compression liquefaction device; the compression liquefaction device is connected to one end of the boiler for storing carbon dioxide.

[0007] However, the aforementioned carbon dioxide capture devices and methods still suffer from low carbon dioxide capture efficiency and insufficient and inefficient utilization of the captured carbon dioxide. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a device system and method for capturing difficult-to-treat flue gas CO2 and coupling it with the synthesis of green chemicals. First, CO2 is captured by electrochemical methods, and then the captured liquid is electrolyzed to produce a mixed gas, thereby realizing the synthesis of green chemicals. This can serve as an important way to quickly realize the coupling of renewable energy with chemical production, improve the flexibility and efficiency of green chemical preparation, and is suitable for large-scale promotion and application.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a device system for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals. The device system includes a first CO2 capture device, a first electrolytic cell, a second CO2 capture device, a heat exchange device, a second electrolytic cell, and a green chemical synthesis device arranged in series.

[0011] The heat exchange device is circulatedly connected to the first CO2 capture device via a heat exchange pipe.

[0012] Difficult-to-treat flue gas contains acidic gases, inert gases, and dust impurities, making it difficult to effectively capture and utilize CO2 using conventional solution scrubbing methods. Since difficult-to-treat flue gas contains a large amount of CO2 (5-40%), developing CO2 capture methods for it is of great significance.

[0013] The apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals, as described in this invention, is equipped with two CO2 capture devices and an electrolytic cell to achieve efficient capture of CO2 from difficult-to-treat flue gas. The captured liquid is then electrolyzed to obtain high-purity raw material gases such as CO2, CO, H2, and O2, which can be used for the synthesis of green chemicals. This achieves the simultaneous capture of CO2 and the preparation of green chemicals, fully leveraging the advantages of electrochemical methods for capturing green carbon sources. The extraction of chemical raw material gases from flue gas ensures a stable and reliable supply of raw materials for chemical production. Furthermore, the captured liquid in the capture device of this invention can be reused repeatedly; only water needs to be added to the captured liquid. The scale of the apparatus system can be modularly expanded according to actual project needs.

[0014] The apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals described in this invention is equipped with a heat exchange device, which can make full use of the waste heat in the difficult-to-treat flue gas, improve energy utilization, and increase the electrolytic conversion efficiency of the second electrolytic cell.

[0015] The green chemical synthesis apparatus described in this invention includes a monocyclic aromatic hydrocarbon synthesis apparatus or a methanol synthesis apparatus, wherein the monocyclic aromatic hydrocarbons include benzene, benzene homologues, and phenyl-substituted unsaturated hydrocarbons. This invention does not impose detailed limitations on the monocyclic aromatic hydrocarbon synthesis apparatus or the methanol synthesis apparatus; any existing apparatus capable of synthesizing monocyclic aromatic hydrocarbons or methanol can be used.

[0016] The first CO2 collection device of this invention is directly connected to the first electrolytic cell. The difficult-to-treat flue gas, after dust removal, directly enters the first CO2 collection device and comes into full contact with the solution, resulting in heat transfer, mass transfer, and chemical reactions. This process removes CO2, SO2, SO3, and NO from the difficult-to-treat flue gas. x Other soluble or reactive impurities are captured in the capture liquid. Due to heat transfer, the temperature of the first capture liquid in the first CO2 capture device rises from room temperature to the optimal electrolysis reaction temperature of 70-80°C in the first electrolytic cell, eliminating the need for an additional preheating system.

[0017] The first CO2 capture device and the first electrolytic cell of this invention prevent SO2, SO3, and NO from being captured. x By allowing acidic gases to enter the second electrolytic cell, the purity of the second mixed gas produced by the second electrolytic cell and the lifespan of the catalyst in the green chemical synthesis unit are prevented from being affected by reduction products (such as N2, NH3 and S), thus improving the purity of the mixed gas and the operational stability of the entire unit system.

[0018] The device system for capturing and coupling difficult-to-treat flue gas CO2 with the synthesis of green chemicals described in this invention can achieve efficient conversion and utilization of captured CO2 through electrolysis, with a conversion rate close to 100%. The gas obtained by electrolysis can be separated and mixed to obtain raw material gas with adjustable composition, which can be used for the synthesis of a variety of green chemicals.

[0019] If only the first CO2 capture device, the first electrolytic cell, and the green chemical synthesis device are connected in series, the first mixed gas generated in the anode chamber of the first electrolytic cell has a high impurity gas content and cannot be directly used for the synthesis of green chemicals.

[0020] Preferably, the first electrolytic cell is connected to the first CO2 collection device via a first collection liquid storage device.

[0021] Preferably, the second electrolytic cell is connected to the second CO2 collection device via a second collection liquid storage device.

[0022] The first and second electrolytic cells of this invention use green electricity as a power source, such as wind power, hydropower, photovoltaic power, biomass power, or ocean energy power.

[0023] Preferably, the anode chamber of the first electrolytic cell is connected to the second CO2 collection device.

[0024] Preferably, the cathode chamber of the first electrolytic cell is connected to the first gas separation device.

[0025] Preferably, the anode chamber of the second electrolytic cell is connected to the green chemical synthesis device via a second gas separation device.

[0026] Preferably, the cathode chamber of the second electrolytic cell is connected to the green chemical synthesis device via a first gas separation device.

[0027] Preferably, the green chemical synthesis device is connected to the green chemical storage device.

[0028] Secondly, the present invention also provides a method for capturing recalcitrant flue gas CO2 coupled with the synthesis of green chemicals, characterized in that the method is carried out using the apparatus system described in the first aspect for capturing recalcitrant flue gas CO2 coupled with the synthesis of green chemicals; the method includes:

[0029] Difficult-to-treat flue gas enters the first CO2 capture device and is captured to form the first capture liquid; the first capture liquid enters the first electrolytic cell to carry out the first electrolytic reaction, the anode chamber generates the first mixed gas, and the cathode chamber generates H2.

[0030] The first mixed gas enters the second CO2 capture device and is captured to form the second capture liquid; after the second capture liquid and the first capture liquid exchange heat in the heat exchange device, they enter the second electrolytic cell to carry out the second electrolytic reaction, where O2 is generated in the anode chamber and the second mixed gas is generated in the cathode chamber; the second mixed gas enters the green chemical synthesis device to carry out the reaction and synthesize green chemicals.

[0031] The method for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals, as described in this invention, is simple to operate and rationally designed. By performing two CO2 capture and electrolytic treatments on the difficult-to-treat flue gas, it achieves efficient capture and reuse of CO2 in the flue gas. This not only effectively reduces carbon emissions but also yields green, high-value chemicals, reducing resource input and achieving a dual carbon reduction effect. The O2 generated in the anode chamber after the second electrolysis reaction can be used in chemical catalysis reactions or in various medical fields. In the entire cycle, the solute in the capture solution is not consumed; only water is consumed. Periodic replenishment of water to the system ensures continuous operation. The operation is simple and low-cost.

[0032] This invention can obtain second mixed gases with different compositions and concentrations by adjusting the voltage, current and other relevant reaction parameters of the second electrolysis reaction. It can also adjust the type of catalyst in the green chemical synthesis device to achieve the synthesis of different types of green chemicals.

[0033] Preferably, the difficult-to-treat flue gas includes any one or a combination of at least two of the following: coal-fired power plant flue gas, coke oven gas, electrolytic aluminum flue gas, or blast furnace gas, and the composition of each flue gas is as follows:

[0034] Flue gas from coal-fired power plants: N2: 50-77%, for example, it can be 50%, 60%, 65%, 70%, 75% or 77%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0035] O2: 2% to 10%, for example, it can be 2%, 3%, 5%, 8%, 9% or 10%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0036] CO2: 12% to 15%, for example, it can be 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0037] H2O: 4% to 12%, for example, it can be 4%, 5%, 7%, 8%, 9%, 10% or 12%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0038] SO2: 0.02% to 0.2%, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.13%, 0.15% or 0.2%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0039] SO3: 1 to 30 ppm, for example, it can be 1 ppm, 5 ppm, 10 ppm, 15 ppm, 18 ppm, 20 ppm or 30 ppm, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0040] NO X : 100 to 1500 ppm, for example, it can be 100 ppm, 300 ppm, 500 ppm, 800 ppm, 1000 ppm, 1300 ppm or 1500 ppm, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0041] Coke oven gas: H2: 40-80%, for example, it can be 40%, 45%, 50%, 55%, 70% or 80%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0042] CH4: 10-55%, for example, it can be 10%, 20%, 30%, 40%, 50% or 55%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0043] Electrolytic aluminum flue gas: Solid fluoride: 8-11 kg / T-Al, for example, it can be 8 kg / T-Al, 8.5 kg / T-Al, 9 kg / T-Al, 9.5 kg / T-Al, 10 kg / T-Al or 11 kg / T-Al, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] HF: 7~12Kg / T-Al, for example, it can be 7Kg / T-Al, 7.5Kg / T-Al, 8Kg / T-Al, 8.5Kg / T-Al, 10Kg / T-Al or 12Kg / T-Al, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] CO2: 900~1800Kg / T-Al, for example, it can be 900Kg / T-Al, 1220Kg / T-Al, 1340Kg / T-Al, 1570Kg / T-Al, 1690Kg / T-Al or 1800Kg / T-Al, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0046] CO: 280~330Kg / T-Al, for example, it can be 280Kg / T-Al, 285Kg / T-Al, 290Kg / T-Al, 295Kg / T-Al, 300Kg / T-Al or 330Kg / T-Al, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0047] SO2: 7.9~15Kg / T-Al, for example, it can be 7.9Kg / T-Al, 8Kg / T-Al, 10Kg / T-Al, 12Kg / T-Al, 14Kg / T-Al or 15Kg / T-Al, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0048] CF4 and C2F6: 0.1 to 0.2 kg / T-Al, for example, 0.1 kg / T-Al, 0.12 kg / T-Al, 0.15 kg / T-Al, 0.17 kg / T-Al, 0.19 kg / T-Al or 0.2 kg / T-Al, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] Blast furnace gas: CO: 20-28%, for example, it can be 20%, 23%, 25%, 27%, 27.5% or 28%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0050] CO2: 17-25%, for example, it can be 17%, 18%, 20%, 23%, 24% or 25%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0051] N2: 50-55%, for example, it can be 50%, 52%, 53%, 54%, 54.5% or 55%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0052] H2: 1 to 5%, for example, it can be 1%, 2%, 3%, 4%, 4.5% or 5%, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0053] Preferably, the temperature of the difficult-to-treat flue gas is 100-150°C, for example, it can be 100°C, 102°C, 110°C, 120°C, 130°C, 140°C or 150°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] Preferably, the first solution in the first CO2 capture device includes any one of NaOH solution, KOH solution, Na2CO3 solution or K2CO3 solution.

[0055] Preferably, the concentration of the first solution is 0.2 to 3.0 mol / L, for example, it can be 0.2 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 2.5 mol / L or 3.0 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0056] Preferably, the temperature of the first solution is 50 to 90°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C or 90°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the anode in the first electrolytic cell is made of any one of titanium, ruthenium, or iridium; and the cathode is made of any one of nickel, cobalt, iron, or ruthenium.

[0058] Preferably, the current density of the first electrolysis reaction is 200–500 mA / cm². 2 For example, it could be 200mA / cm 2 220mA / cm 2 250mA / cm 2 300mA / cm 2 400mA / cm 2 Or 500mA / cm 2 This applies to, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0059] Preferably, the temperature of the first electrolysis reaction is 50 to 90°C, for example, it can be 50°C, 60°C, 64°C, 70°C, 77°C, 80°C or 90°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] Preferably, the second solution in the second CO2 capturing device includes any one of NaOH solution, KOH solution, Na2CO3 solution or K2CO3 solution.

[0061] Preferably, the concentration of the second solution is 0.5 to 5.0 mol / L, for example, it can be 0.5 mol / L, 0.8 mol / L, 1 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0062] Because the present invention incorporates a second CO2 collection device and a second electrolytic cell, and the collection solution in the second CO2 collection device has a higher concentration, the circulation volume of the solution in the electrolytic cell and the collection device can be reduced.

[0063] Preferably, the temperature of the second solution is 20 to 40°C, for example, it can be 20°C, 22°C, 25°C, 30°C, 35°C, 38°C or 40°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0064] Preferably, the anode in the second electrolytic cell is made of any one of nickel, titanium, ruthenium, or iridium; and the cathode is made of any one of silver, gold, or zinc.

[0065] The cathode in the second electrolytic cell is preferably made of any one of silver, gold or zinc, and is made of a different material than the cathode in the first electrolytic cell. It has better electrocatalytic CO2 reduction to syngas activity and good long-term operating stability.

[0066] Preferably, the current density of the second electrolysis reaction is 510–1200 mA / cm². 2 For example, it could be 510A / cm 2 630A / cm 2 750A / cm 2 860A / cm 2 900A / cm 2 Or 1200A / cm 2 This applies to, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0067] Preferably, the current density of the second electrolysis reaction is greater than that of the first electrolysis reaction, which can increase the CO2 processing capacity and reduce the electrode area and the size of the electrolysis cell, thus making the system more efficient and economical.

[0068] Preferably, the temperature of the second electrolysis reaction is 20 to 40°C, for example, it can be 20°C, 22°C, 25°C, 30°C, 35°C, 38°C or 40°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0069] Preferably, the temperature of the second electrolysis reaction is lower than that of the first electrolysis reaction, which is beneficial for operation and reduces electrolyte loss.

[0070] Preferably, the first mixed gas includes CO2 and O2.

[0071] Preferably, the purity of H2 generated in the cathode chamber of the first electrolytic cell is 99% or higher, for example, it can be 99.1%, 99.3%, 99.5%, 99.7%, 99.8% or 99.9%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0072] Preferably, the purity of O2 produced in the anode chamber of the second electrolytic cell is 99% or higher, for example, it can be 99.1%, 99.3%, 99.5%, 99.7%, 99.8% or 99.9%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0073] Preferably, the second gas mixture includes H2 and CO.

[0074] Preferably, the concentration of H2 in the second mixture is 5% to 90%, for example, it can be 5%, 10%, 20%, 40%, 80% or 90%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0075] As a preferred technical solution of the present invention, the method includes:

[0076] Difficult-to-treat flue gas at a temperature of 100-150°C enters the first CO2 capture device and is captured to form the first capture liquid; the first capture liquid enters the first electrolytic cell to carry out the first electrolytic reaction, the anode chamber generates the first mixed gas, and the cathode chamber generates H2 with a purity of more than 99%; the first mixed gas includes CO2 and O2.

[0077] The difficult-to-treat flue gas includes any one or a combination of at least two of the following: flue gas from coal-fired power plants, coke oven gas, electrolytic aluminum gas, or blast furnace gas. The composition of each flue gas is as follows:

[0078] Flue gas from coal-fired power plants: N2: 50-77%; O2: 2%-10%; CO2: 12%-15%; H2O: 4%-12%; SO2: 0.02%-0.2%; SO3: 1-30ppm; NO X : 100~1500ppm;

[0079] Coke oven gas: H2: 40-80%; CH4: 10-55%;

[0080] Electrolytic aluminum flue gas: Solid fluorides: 8-11 kg / T-Al; HF: 7-12 kg / T-Al; CO2: 900-1800 kg / T-Al; CO: 280-330 kg / T-Al; SO2: 7.9-15 kg / T-Al; CF4 and C2F6: 0.1-0.2 kg / T-Al;

[0081] Blast furnace gas: CO: 20-28%; CO2: 17-25%; N2: 50-55%; H2: 1-5%;

[0082] The first solution in the first CO2 capture device includes any one of NaOH solution, KOH solution, Na2CO3 solution or K2CO3 solution; the concentration of the first solution is 0.2 to 3.0 mol / L, and the temperature is 50 to 90℃;

[0083] The anode in the first electrolytic cell is made of any one of titanium, ruthenium, or iridium; the cathode is made of any one of nickel, cobalt, iron, or ruthenium; and the current density of the first electrolytic reaction is 200–500 mA / cm². 2 The temperature is 50–90℃;

[0084] The first mixed gas enters the second CO2 capture device and is captured to form the second capture liquid; after the second capture liquid and the first capture liquid exchange heat in the heat exchange device, they enter the second electrolytic cell to carry out the second electrolytic reaction, where the anode chamber produces O2 with a purity of more than 99%, and the cathode chamber produces the second mixed gas; the second mixed gas includes H2 and CO; the concentration of H2 in the second mixed gas is 5-90%;

[0085] The second mixed gas enters the green chemical synthesis unit to react and synthesize green chemicals;

[0086] The second solution in the second CO2 capture device includes any one of NaOH solution, KOH solution, Na2CO3 solution, or K2CO3 solution; the concentration of the second solution is 0.5–5.0 mol / L; and the temperature of the second solution is 20–40°C.

[0087] The anode in the second electrolytic cell is made of any one of nickel, titanium, ruthenium, or iridium; the cathode is made of any one of silver, gold, or zinc; and the current density of the second electrolytic reaction is 510–1200 mA / cm². 2 The temperature is 20–40℃.

[0088] Compared with the prior art, the present invention has at least the following beneficial effects:

[0089] (1) The device system and method for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals provided by the present invention can achieve the purpose of pre-capturing carbon from various difficult-to-treat flue gas sources, and at the same time can realize the efficient reuse of CO2 after capture; the solute in the capture liquid is not consumed in the entire cycle process, only water is consumed, and the continuous operation of the system can be achieved by periodically adding water to the system.

[0090] (2) The device system for capturing CO2 in difficult-to-treat flue gas coupled with the synthesis of green chemicals provided by the present invention can significantly improve the purity of the mixed gas generated by electrolysis and extend the service life of the catalyst in the synthesis of green chemicals by setting up two sets of CO2 capture devices and electrolytic cells.

[0091] (3) The apparatus system and method for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals provided by the present invention uses CO2 from difficult-to-treat flue gas as raw material, which not only effectively reduces carbon emissions, but also obtains green high-value chemicals, reduces the consumption of mineral resources, and achieves a dual carbon reduction effect; the gas generated by electrolysis can also be used in chemical catalysis, medical and other fields. Attached Figure Description

[0092] Figure 1 is a schematic diagram of the apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals in Embodiment 1 of the present invention.

[0093] In the diagram: 1-First CO2 capture device; 2-First conveying device; 3-Second conveying device; 4-First power source; 5-First electrolytic cell; 6-First capture liquid storage device; 7-First valve; 8-Second CO2 capture device; 9-Heat exchange device; 10-Third conveying device; 11-Fourth conveying device; 12-Second power source; 13-Second electrolytic cell; 14-Second capture liquid storage device; 15-Second gas separation device; 16-First gas separation device; 17-Second valve; 18-Third valve; 19-Fourth valve; 20-Fifth valve; 21-Sixth valve; 22-Seventh valve; 23-Green chemical synthesis device; 24-Green chemical storage device. Detailed Implementation

[0094] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0095] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0096] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0097] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0098] Those skilled in the art should understand that the present invention necessarily includes the necessary pipelines, conventional valves and general pump equipment for achieving process integrity, but the above content is not the main inventive point of the present invention. Those skilled in the art can add layouts based on process flow and equipment structure selection, and the present invention does not make any special requirements or specific limitations in this regard.

[0099] Example 1

[0100] This embodiment provides a device system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals, as shown in Figure 1.

[0101] The device system includes a first CO2 capture device 1, a first electrolytic cell 5, a second CO2 capture device 8, a heat exchange device 9, a second electrolytic cell 13, and a green chemical synthesis device 23, which are connected in series.

[0102] The heat exchange device 9 is circulatedly connected to the first CO2 capture device 1 via a heat exchange pipe.

[0103] A third conveying device 10 is provided between the heat exchange device 9 and the second electrolytic cell 13.

[0104] A first conveying device 2 is provided between the first CO2 capture device 1 and the first electrolytic cell 5.

[0105] The first electrolytic cell 5 is connected to the first CO2 capturing device 1 via the first capturing liquid storage device 6; a second conveying device 3 is provided between the first capturing liquid storage device 6 and the first CO2 capturing device 1.

[0106] The first electrolytic cell 5 uses a first power supply 4; the second electrolytic cell 13 uses a second power supply 12.

[0107] The second electrolytic cell 13 is connected to the second CO2 collection device 8 via the second collection liquid storage device 14 and the fourth conveying device 11.

[0108] The anode chamber of the first electrolytic cell 5 is connected to the second CO2 collection device 8 via the first valve 7;

[0109] The cathode chamber of the first electrolytic cell 5 is connected to the first gas separation device 16.

[0110] The anode chamber of the second electrolytic cell 13 is connected to the green chemical synthesis device 23 via the second gas separation device 15; a fourth valve 19 is provided between the second gas separation device 15 and the green chemical synthesis device 23; a sixth valve 21 is provided between the fourth valve 19 and the green chemical synthesis device 23; the second gas separation device 15 is connected to the second valve 17.

[0111] The cathode chamber of the second electrolytic cell 13 is connected to the green chemical synthesis device 23 via the first gas separation device 16; a fifth valve 20 is provided between the first gas separation device 16 and the green chemical synthesis device 23; a seventh valve 22 is provided between the fifth valve 20 and the green chemical synthesis device 23; the first gas separation device 16 is connected to the third valve 18.

[0112] The green chemical synthesis device 23 is connected to the green chemical storage device 24.

[0113] Example 2

[0114] This embodiment provides a method for capturing CO2 from flue gas of a coal-fired power plant and coupling it with the synthesis of green chemicals. The method is carried out using the apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals as described in Example 1.

[0115] The temperature of the flue gas from the coal-fired power plant is 125℃, and the pressure is close to atmospheric pressure. The composition of the flue gas from this coal-fired power plant is shown in Table 1.

[0116] Table 1

[0117] IngredientsN2O2CO2H2OSO2SO3NOX Content: 77% 4-5% 12-15% 4-12% 0.02-0.2% 1-30 ppm 100-1500 ppm surface

[0118] The method includes:

[0119] Flue gas from a coal-fired power plant enters the first CO2 capture device and is captured to form the first capture liquid; the first capture liquid enters the first electrolytic cell to carry out the first electrolytic reaction, the anode chamber generates the first mixed gas, and the cathode chamber generates H2 with a purity of 99.5%; the first mixed gas includes CO2 and O2;

[0120] The first solution in the first CO2 capture device is a NaOH solution; the concentration of the first solution is 0.8 mol / L, and the temperature is 80℃.

[0121] The anode in the first electrolytic cell is a titanium plate; the cathode comprises nickel foam; the current density of the first electrolytic reaction is 300 mA / cm². 2 The temperature is 80℃;

[0122] The first mixed gas enters the second CO2 capture device and is captured to form the second capture liquid; after the second capture liquid and the first capture liquid exchange heat in the heat exchange device, they enter the second electrolytic cell to carry out the second electrolytic reaction. The anode chamber produces O2 with a purity of 99.8%, and the cathode chamber produces the second mixed gas; the second mixed gas includes H2 and CO; the concentration of H2 in the second mixed gas is 85.7%;

[0123] The second mixed gas enters the green chemical synthesis unit to react and synthesize the green chemical monocyclic aromatic hydrocarbon;

[0124] The second solution in the second CO2 capture device is a KOH solution; the concentration of the second solution is 1.0 mol / L; the temperature of the second solution is 30℃.

[0125] The anode in the second electrolytic cell is nickel; the cathode is silver; and the current density of the second electrolytic reaction is 550 mA / cm². 2 The temperature is 30℃.

[0126] The method described in this embodiment is for a 300MW coal-fired power plant, which produces up to 180 tons of CO2 in its flue gas per hour. Based on 4000 hours of annual operation, the annual CO2 emissions reach as high as 720,000 tons, providing ample raw materials for the preparation of high-value chemicals. Taking an annual production of 15 tons of monocyclic aromatic hydrocarbons as an example, the coal-fired power plant only needs to capture 200 tons of pure CO2 annually, with an annual flue gas treatment capacity of approximately 848,000 m³. 3 Approximately 102,000 m³ of CO2 was recovered. 3 .

[0127] The anode of the second electrolytic cell can produce 508.7 tons of O2, and the cathode electrolysis can produce about 181.8 tons of syngas, of which the amount of CO is 127.3 tons and the amount of H2 is 54.5 tons.

[0128] Example 3

[0129] This embodiment provides a method for capturing CO2 from coke oven gas and coupling it with the synthesis of green chemicals. The method is carried out using the apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals as described in Example 1.

[0130] Coke oven gas consists of 56% H2 and 27% CH4, as well as small amounts of CO, CO2, N2, O2 and other hydrocarbons. The flue gas temperature after coke oven gas combustion is 100℃.

[0131] The method includes:

[0132] The flue gas after coke oven gas combustion enters the first CO2 capture device and is captured to form the first capture liquid; the first capture liquid enters the first electrolytic cell to carry out the first electrolytic reaction, the anode chamber generates the first mixed gas, and the cathode chamber generates H2 with a purity of 99%; the first mixed gas includes CO2 and O2.

[0133] The first solution in the first CO2 capture device is a NaOH solution; the concentration of the first solution is 1.5 mol / L, and the temperature is 60℃.

[0134] The anode in the first electrolytic cell is made of ruthenium; the cathode is made of iron; and the current density of the first electrolytic reaction is 250 mA / cm². 2 The temperature is 60℃;

[0135] The first mixed gas enters the second CO2 capture device and is captured to form the second capture liquid; after the second capture liquid and the first capture liquid exchange heat in the heat exchange device, they enter the second electrolytic cell to carry out the second electrolytic reaction, where the anode chamber produces O2 with a purity of 99% and the cathode chamber produces the second mixed gas; the second mixed gas includes H2 and CO; the concentration of H2 in the second mixed gas is 85.7%;

[0136] The second mixed gas enters the green chemical synthesis unit to react and synthesize the green chemical monocyclic aromatic hydrocarbon;

[0137] The second solution in the second CO2 capture device includes a NaOH solution; the concentration of the second solution is 1.2 mol / L; the temperature of the second solution is 40°C.

[0138] The anode in the second electrolytic cell is made of titanium; the cathode is made of gold; and the current density of the second electrolytic reaction is 800 mA / cm².2 The temperature is 40℃.

[0139] This embodiment takes the annual capture of 100 tons of pure CO2 from the flue gas after coke oven gas combustion as an example, with an annual flue gas treatment capacity of approximately 350,000 m³. 3 Approximately 51,000 m³ of CO2 was recovered. 3 .

[0140] The anode of the second electrolytic cell can produce 254.7 tons of O2, and the cathode electrolysis can produce about 90.9 tons of syngas, of which the amount of CO is 63.6 tons and the amount of H2 is 27.3 tons. It can also produce about 7.2 tons of monocyclic aromatic hydrocarbons.

[0141] Example 4

[0142] This embodiment provides a method for capturing CO2 from electrolytic aluminum flue gas and coupling it with the synthesis of green chemicals. The method is carried out using the apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals as described in Example 1.

[0143] The main components of the electrolytic aluminum flue gas are: solid fluorides: 8-11 kg / T-Al; HF: 7-12 kg / T-Al; CO2: 900-1800 kg / T-Al; CO: 280-330 kg / T-Al; SO2: 7.9-15 kg / T-Al; CF4 and C2F6: 0.1-0.2 kg / T-Al.

[0144] The method includes:

[0145] The aluminum electrolysis flue gas enters the first CO2 capture device and is captured to form the first capture liquid; the first capture liquid enters the first electrolytic cell to carry out the first electrolysis reaction, the anode chamber generates the first mixed gas, and the cathode chamber generates H2 with a purity of 99.2%; the first mixed gas includes CO2 and O2;

[0146] The first solution in the first CO2 capture device is a K2CO3 solution; the concentration of the first solution is 1.2 mol / L, and the temperature is 80℃.

[0147] The anode in the first electrolytic cell is made of titanium; the cathode is made of ruthenium; and the current density of the first electrolytic reaction is 230 mA / cm². 2 The temperature is 80℃;

[0148] The first mixed gas enters the second CO2 capture device and is captured to form the second capture liquid; after the second capture liquid and the first capture liquid exchange heat in the heat exchange device, they enter the second electrolytic cell to carry out the second electrolysis reaction, producing a mixed gas of CO2 and O2 in the anode chamber and a second mixed gas in the cathode chamber; the second mixed gas includes H2 and CO; the concentration of H2 in the second mixed gas is 77.8%;

[0149] The second mixed gas enters the green chemical synthesis unit to react and synthesize the green chemical methanol;

[0150] The second solution in the second CO2 capture device is a KOH solution; the concentration of the second solution is 1.2 mol / L; the temperature of the second solution is 35℃.

[0151] The anode in the second electrolytic cell is iridium; the cathode is silver; and the current density of the second electrolytic reaction is 950 mA / cm². 2 The temperature is 35℃.

[0152] This embodiment takes the annual capture of 100 tons of pure CO2 from electrolytic aluminum flue gas as an example, with an annual flue gas treatment capacity of approximately 350,000 m³. 3 Approximately 51,000 m³ of CO2 was recovered. 3 .

[0153] In this embodiment, the electrolyte in the second electrolyzer is nearly saturated with CO2, and CO2 will be generated during the electrolysis process. Anodic electrolysis in the second electrolyzer yields 14.3 tons of CO2 and 140 tons of O2, while cathodic electrolysis produces approximately 68 tons of syngas, including 54.5 tons of CO and 13.6 tons of H2, which can be used to produce approximately 65 tons of methanol.

[0154] Example 5

[0155] This embodiment provides a method for capturing CO2 from blast furnace gas and coupling it with the synthesis of green chemicals. The method is carried out using the apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals as described in Example 1.

[0156] The composition of blast furnace gas is 20-28% CO, 17-25% CO2, 50-55% N2 and 1-5% H2.

[0157] The method includes:

[0158] Blast furnace gas enters the first CO2 capture device and is captured to form the first capture liquid; the first capture liquid enters the first electrolytic cell to carry out the first electrolytic reaction, the anode chamber generates the first mixed gas, and the cathode chamber generates H2 with a purity of 99.1%; the first mixed gas includes CO2 and O2;

[0159] The first solution in the first CO2 capture device is a KOH solution; the concentration of the first solution is 0.4 mol / L, and the temperature is 80℃.

[0160] The anode in the first electrolytic cell is made of titanium; the cathode is made of nickel; and the current density of the first electrolytic reaction is 300 mA / cm². 2 The temperature is 80℃;

[0161] The first mixed gas enters the second CO2 capture device and is captured to form the second capture liquid; after the second capture liquid and the first capture liquid exchange heat in the heat exchange device, they enter the second electrolytic cell to carry out the second electrolytic reaction. The anode chamber produces O2 with a purity of 99.5%, and the cathode chamber produces the second mixed gas; the second mixed gas includes H2 and CO; the concentration of H2 in the second mixed gas is 85.7%;

[0162] The second mixed gas enters the green chemical synthesis unit to react and synthesize the green chemical monocyclic aromatic hydrocarbon;

[0163] The second solution in the second CO2 capture device includes a KOH solution; the concentration of the second solution is 1 mol / L; and the temperature of the second solution is 20°C.

[0164] The anode in the second electrolytic cell is made of nickel; the cathode is made of zinc; and the current density of the second electrolytic reaction is 1100 mA / cm². 2 The temperature is 20℃.

[0165] This example uses the capture of 150 tons of pure CO2 from blast furnace gas annually as an example, with an annual blast furnace gas processing capacity of approximately 382,000 m³. 3 Approximately 76,000 m³ of CO2 was recovered. 3 .

[0166] The second electrolytic cell can produce 381.8 tons of O2 at the anode and about 136.4 tons of syngas at the cathode, of which 95.5 tons are CO and 40.9 tons are H2. It can also produce about 10.9 tons of monocyclic aromatic hydrocarbons.

[0167] Comparative Example 1

[0168] This comparative example provides a device system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals. Except for the absence of a second CO2 capture device, a heat exchange device, and a second electrolytic cell, the device system is the same as that in Example 1.

[0169] This comparative example also provides a method for capturing CO2 from flue gas of a coal-fired power plant and coupling it with the synthesis of green chemicals. The method is carried out using the above-mentioned apparatus system for capturing CO2 from difficult-to-treat flue gas and coupling it with the synthesis of green chemicals. Except for directly feeding the first mixed gas generated in the anode chamber of the first electrolytic cell and the H2 generated in the cathode chamber into the green chemical synthesis apparatus, the method is the same as in Example 2.

[0170] The method described in this comparative example is for a 300MW coal-fired power plant, which produces up to 180 tons of CO2 per hour in its flue gas. Based on 4000 hours of annual utilization, the annual CO2 emissions reach as high as 720,000 tons, providing ample raw materials for the preparation of high-value chemicals. Taking an annual production of 15 tons of monocyclic aromatic hydrocarbons as an example, a coal-fired power plant would need to capture 800 tons of CO2 annually, requiring an annual flue gas treatment capacity of approximately 3.392 million m³. 3 Approximately 408,000 m³ of CO2 was recovered. 3 .

[0171] In this comparative example, the purity of CO2 in the first mixed gas produced in the anode chamber of the first electrolytic cell is only 60%, and it needs to be separated before entering the green chemical synthesis device. The purity of H2 produced in the cathode chamber is 99%. The separated CO2 and H2 produced in the cathode chamber are used as raw materials for the monocyclic aromatic hydrocarbon synthesis reaction. The yield of monocyclic aromatic hydrocarbons obtained is low at 6%, and the presence of impurities in the gas will affect the service life of the catalyst used in the monocyclic aromatic hydrocarbon synthesis.

[0172] In summary, the apparatus system and method for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals provided by this invention employs two sets of CO2 capture devices and an electrolytic cell, achieving efficient capture of CO2 from difficult-to-treat flue gas. Furthermore, the capture liquid is electrolyzed to obtain raw material gas with higher purity, which is suitable for the synthesis of green chemicals. The green chemicals prepared have high purity and high yield, resulting in significant economic benefits.

[0173] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0174] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A device system for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals, characterized in that, The device system includes a first CO2 capture device, a first electrolytic cell, a second CO2 capture device, a heat exchange device, a second electrolytic cell, and a green chemical synthesis device arranged in series; the heat exchange device is circulatedly connected to the first CO2 capture device via heat exchange pipes.

2. The device system according to claim 1, characterized in that, The first electrolytic cell is connected to the first CO2 capturing device via a first capturing liquid storage device; preferably, the second electrolytic cell is connected to the second CO2 capturing device via a second capturing liquid storage device.

3. The device system according to claim 1 or 2, characterized in that, The anode chamber of the first electrolytic cell is connected to the second CO2 capture device; preferably, the cathode chamber of the first electrolytic cell is connected to the first gas separation device.

4. The apparatus system according to any one of claims 1 to 3, characterized in that, The anode chamber of the second electrolytic cell is connected to the green chemical synthesis device via a second gas separation device; preferably, the cathode chamber of the second electrolytic cell is connected to the green chemical synthesis device via a first gas separation device.

5. The apparatus system according to any one of claims 1 to 4, characterized in that, The green chemical synthesis unit is connected to the green chemical storage unit.

6. A method for capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals, characterized in that, The method employs the apparatus system described in any one of claims 1 to 5, which involves capturing CO2 from difficult-to-treat flue gas coupled with the synthesis of green chemicals. The method includes: capturing difficult-to-treat flue gas in a first CO2 capture device to form a first capture liquid; the first capture liquid entering a first electrolytic cell for a first electrolytic reaction, generating a first mixed gas in the anode chamber and H2 in the cathode chamber; the first mixed gas entering a second CO2 capture device for capture to form a second capture liquid; the second capture liquid exchanging heat with the first capture liquid in a heat exchanger entering a second electrolytic cell for a second electrolytic reaction, generating O2 in the anode chamber and a second mixed gas in the cathode chamber; and the second mixed gas entering a green chemical synthesis device for reaction to synthesize green chemicals.

7. The method according to claim 6, characterized in that, The difficult-to-treat flue gas includes any one or a combination of at least two of the following: coal-fired power plant flue gas, coke oven gas, electrolytic aluminum flue gas, or blast furnace gas. The composition of each flue gas is as follows: Coal-fired power plant flue gas: N2: 50–77%; O2: 2%–10%; CO2: 12%–15%; H2O: 4%–12%; SO2: 0.02%–0.2%; SO3: 1–30 ppm; NO… X : 100-1500ppm; coke oven gas: H2: 40-80%; CH4: 10-55%; electrolytic aluminum flue gas: solid fluorides: 8-11Kg / T-Al; HF: 7-12Kg / T-Al; CO2: 900-1800Kg / T-Al; CO: 280-330Kg / T-Al; SO2: 7.9-15Kg / T-Al; CF4 and C2F6: 0.1-0.2Kg / T-Al; blast furnace gas: CO: 20-28%; CO2: 17-25%; N2: 50-55%; H2: 1-5%; preferably, the temperature of the difficult-to-treat flue gas is 100-150℃.

8. The method according to claim 6 or 7, characterized in that, The first solution in the first CO2 capture device includes any one of NaOH solution, KOH solution, Na2CO3 solution, or K2CO3 solution; preferably, the concentration of the first solution is 0.2–3.0 mol / L; preferably, the temperature of the first solution is 50–90°C; preferably, the anode material in the first electrolytic cell includes any one of titanium, ruthenium, or iridium; the cathode material includes any one of nickel, cobalt, iron, or ruthenium; preferably, the current density of the first electrolysis reaction is 200–500 mA / cm². 2 Preferably, the temperature of the first electrolysis reaction is 50–90°C.

9. The method according to any one of claims 6 to 8, characterized in that, The second solution in the second CO2 capture device includes any one of NaOH solution, KOH solution, Na2CO3 solution, or K2CO3 solution; preferably, the concentration of the second solution is 0.5–5.0 mol / L; preferably, the temperature of the second solution is 20–40°C; preferably, the anode material in the second electrolytic cell includes any one of nickel, titanium, ruthenium, or iridium; the cathode material includes any one of silver, gold, or zinc; preferably, the current density of the second electrolysis reaction is 510–1200 mA / cm². 2 Preferably, the temperature of the second electrolysis reaction is 20–40°C.

10. The method according to any one of claims 6 to 9, characterized in that, The first mixed gas includes CO2 and O2; preferably, the purity of H2 generated in the cathode chamber of the first electrolytic cell is 99% or higher; preferably, the purity of O2 generated in the anode chamber of the second electrolytic cell is 99% or higher; preferably, the second mixed gas includes H2 and CO; preferably, the concentration of H2 in the second mixed gas is 5-90%.

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