CN117358037A - Carbon dioxide capturing method and system thereof - Google Patents

Abstract

The invention provides a carbon dioxide capturing method and a system thereof, wherein the method comprises the following steps: (1) Allowing the gas to be treated to pass through the membrane component and then enter an absorbent aqueous solution for carbon dioxide absorption treatment to obtain absorption liquid; (2) The absorption liquid is subjected to electrolytic treatment to obtain carbon dioxide, and the method not only can realize effective capture of the carbon dioxide and reduce secondary pollution, but also greatly reduces energy consumption.

Description

Carbon dioxide capture method and system

Technical field

The invention belongs to the technical field of carbon dioxide capture, and specifically relates to a carbon dioxide capture method and its system.

Background technique

Low-carbon emission reduction technologies are the focus of attention from industry and academia. Direct capture of CO ₂ (DAC) technology refers to the capture of carbon dioxide (CO ₂ ) from ambient air. This technology can effectively reduce the concentration of CO ₂ in the atmosphere and is an important technical path to achieve carbon neutrality.

Currently, DAC technology includes solvent method and adsorption method. The solvent method refers to using an alkaline solution to absorb CO ₂ in the air to produce carbonate precipitates, and then calcining and regenerating the generated carbonate precipitates. The solvent method often consumes a large amount of water, and the calcination regeneration temperature is often as high as 900°C, which consumes a lot of energy. The adsorption method refers to using adsorbents to absorb CO ₂ in the air. On the one hand, the adsorption capacity of common adsorbents is small. Based on the need to increase the adsorption capacity, the amount of adsorbent is often increased. However, too much adsorbent will cause the adsorption equipment to be too large. Although organic amine modified adsorbents Compared with other adsorbents, it has relatively excellent adsorption capacity, but the easy loss of organic amines often leads to secondary pollution of the environment. On the other hand, the solid-state characteristics of the adsorbent lead to poor fluidity, which in turn creates a certain degree of difficulty in its recovery and regeneration.

Contents of the invention

The invention provides a carbon dioxide capture method and a system thereof. The method uses a membrane absorption method to capture carbon dioxide in the gas to be treated, and then uses an electrochemical method to regenerate the carbon dioxide. This method can not only achieve effective capture of carbon dioxide, but also reduce Secondary pollution, greatly reducing energy consumption.

One aspect of the present invention provides a method for capturing carbon dioxide, which includes the following steps: (1) passing the gas to be treated through a membrane module and then entering an absorbent aqueous solution to absorb carbon dioxide to obtain an absorption liquid; (2) treating the absorption liquid Perform electrolysis to obtain carbon dioxide.

According to one embodiment of the present invention, the absorbent aqueous solution is an alkaline aqueous solution.

According to an embodiment of the present invention, the absorbent includes at least one of alkaline inorganic substances and nitrogen-containing organic substances; the nitrogen-containing organic substances include at least one of amino acid salts and organic alcohol amines.

According to an embodiment of the present invention, the mass concentration of the absorbent in the aqueous absorbent solution is 10wt%-60wt%.

According to an embodiment of the present invention, the gas-liquid ratio of the gas to be treated and the absorbent aqueous solution is (20m ³ -1000m ³ ): 1L.

According to an embodiment of the present invention, the pore diameter of the membrane is 0.2 μm or less, and the porosity is 30%-50%.

According to an embodiment of the present invention, the raw material composition of the membrane includes at least one of polypropylene, polytetrafluoroethylene, and polyvinylidene fluoride.

According to an embodiment of the present invention, the electrolysis conditions of the electrolysis treatment are: current density is 2mA/cm ² -3mA/cm ² and temperature is 50°C-80°C.

Another aspect of the present invention provides a carbon dioxide capture system for implementing the above carbon dioxide capture method, including: an absorption unit for absorbing carbon dioxide from the gas to be processed, and at least one membrane module is provided in the absorption unit , the gas phase inlet of the absorption unit is used to introduce the gas to be treated, and the liquid phase inlet of the absorption unit is used to introduce the absorbent aqueous solution; the regeneration unit is equipped with an electrolysis device for electrolyzing the absorption liquid. The regeneration unit The inlet is connected with the liquid phase outlet of the absorption unit.

According to an embodiment of the present invention, it also includes a separation unit for separating carbon dioxide, and the inlet of the separation unit is connected with the gas phase outlet of the regeneration unit; and/or it also includes a power supply to provide DC power to the cathode and anode of the electrolysis device.

The implementation of the present invention has at least the following beneficial effects:

The carbon dioxide capture method provided by the present invention uses a membrane absorption method to capture carbon dioxide in the gas to be treated, and then uses an electrochemical method to regenerate the carbon dioxide. In the membrane absorption method, the gas to be treated enters the absorbent aqueous solution after passing through the membrane module. The absorbent aqueous solution can capture the carbon dioxide in the gas to be treated. In addition, the membrane module is used as the separation interface between the gas and liquid phases, reducing the absorbent aqueous solution. The loss of absorbent aqueous solution avoids increased water consumption and secondary pollution due to the loss of absorbent aqueous solution. Using electrochemical method to treat the absorption liquid can not only regenerate carbon dioxide under mild conditions, but also electrolyze water to produce hydrogen, realize the co-production of carbon dioxide regeneration and hydrogen, reduce energy consumption, and increase the added value of products.

In addition, the carbon dioxide capture method provided by the present invention is simple and easy to operate, does not require harsh conditions such as high temperature, is low in cost, environmentally friendly, and is conducive to actual industrial production and application.

Description of the drawings

Figure 1 is a flow chart of the carbon dioxide capture method of this embodiment 1.

Detailed ways

The specific embodiments listed below only describe the principles and features of the present invention, and the examples are only used to explain the present invention and do not limit the scope of the present invention. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

It should be noted that in the description of the present invention, unless otherwise clearly stated and limited, the terms "set", "connected", "connected", etc. should be understood in a broad sense. For example, connection can be direct connection or connection. Indirect connections through intermediaries. For those of ordinary skill in the art, the above-mentioned specific meanings in the present invention can be understood in specific situations.

The invention provides a method for capturing carbon dioxide, which includes the following steps: (1) allowing the gas to be treated to pass through a membrane module and then enter an absorbent aqueous solution to absorb carbon dioxide to obtain an absorption liquid; (2) electrolyze the absorption liquid, Get carbon dioxide.

The carbon dioxide capture method provided by the present invention uses a membrane absorption method to capture carbon dioxide in the gas to be treated, and then uses an electrochemical method to regenerate the carbon dioxide. The above-mentioned membrane absorption method is a method that combines membrane and absorption methods. After the carbon dioxide in the gas to be treated passes through the membrane module, it enters the absorbent aqueous solution and reacts and is removed. The carbon dioxide enters the absorbent aqueous solution and reacts to form a carbon dioxide absorption liquid. , the electrolysis treatment of the absorption liquid can realize the recovery of carbon dioxide products under mild conditions.

The carbon dioxide capture method provided by the present invention is suitable for capturing carbon dioxide in gases containing carbon dioxide, and is especially suitable for capturing low-concentration carbon dioxide. For example, it can be used to capture carbon dioxide from the air, and can achieve large-scale carbon emission reduction. Air diffuses through the pores of the membrane and diffuses from the gas phase to the membrane-liquid interface. The carbon dioxide in the air reacts chemically with the absorbent aqueous solution, causing the concentration of carbon dioxide at the membrane-liquid interface to be almost zero. Driven by the concentration difference, the carbon dioxide further increases. It diffuses toward the side of the absorbent aqueous solution, reacts chemically with the absorbent aqueous solution, and is removed. The solubility of other components in the air (such as nitrogen and oxygen) in the absorbent aqueous solution is very low and hardly reacts with the absorbent aqueous solution. Therefore, other components in the air cannot pass through the membrane module without the driving effect of concentration difference. .

After research and analysis, the inventor believes that the membrane module can also serve as a separation interface between the gas and liquid phases, preventing leakage of the liquid phase and reducing energy consumption and secondary pollution. The absorbent aqueous solution is electrolyzed using an electrochemical method. The electrolysis recovery of carbon dioxide is accompanied by the production of hydrogen. As a clean and safe energy source, hydrogen effectively increases the added value and is conducive to large-scale promotion and application.

Normally, before the gas to be treated passes through the membrane module, the gas to be treated is also pretreated, mainly to remove moisture and particulate matter in the gas to be treated, effectively protecting the normal operation of subsequent membrane modules and preventing Affects the carbon dioxide capture effect. Pretreatment can include filtration, drying, etc.

In the present invention, the carbon dioxide in the gas to be treated passes through the membrane module and enters the absorbent aqueous solution to undergo a chemical reaction. The content of carbon dioxide in the reacted gas is greatly reduced, and an absorption liquid is generated. The pore diameter of the membrane is 0.2 μm or less, preferably 0.01 μm-0.1 μm, and the porosity is 30-50%.

The present invention does not limit the specific type of the absorbent aqueous solution. For example, in some embodiments, since carbon dioxide is an acid gas, alkaline or alkaline salt solutions can be preferably used as the absorbent aqueous solution for absorption. In order to ensure that the absorbent aqueous solution has strong reactivity with carbon dioxide and can absorb carbon dioxide with high selectivity, in some embodiments, the absorbent aqueous solution is an alkaline aqueous solution.

In the above embodiment, carbon dioxide reacts chemically with the absorbent aqueous solution to obtain an absorption liquid. The absorption liquid contains carbon-containing anions, such as carbonate ions or bicarbonate ions.

The above-mentioned absorbent can be a conventional carbon dioxide absorbent in this field. In order to further enhance the absorption capacity of the aqueous absorbent solution for carbon dioxide and to facilitate the subsequent electrolysis recovery of carbon dioxide, a water-soluble absorbent is usually selected. In the specific implementation process of the present invention, , you can first dissolve the absorbent in water and configure it into an aqueous absorbent solution. The mass concentration of the absorbent is 10wt%-60wt%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40% , 45%, 50%, 55%, 60% or any two of them.

In the above embodiment, the absorbent includes at least one of alkaline inorganic substances and nitrogen-containing organic substances, preferably a mixture of alkaline inorganic substances and nitrogen-containing organic substances, wherein the alkaline inorganic substances include potassium hydroxide and sodium hydroxide. At least one of the nitrogen-containing organic substances includes at least one of amino acid salts and organic alcohol amines, such as potassium glycinate, 2-amino-2-methyl-1-propanol (AMP), etc.

In the present invention, the flow rate of the gas to be treated and the flow rate of the absorbent solution can be adjusted to maintain a stable reaction between the gas and the liquid and achieve stable and effective capture of carbon dioxide in the gas. In some embodiments, the gas to be treated and the absorbent solution The gas-liquid ratio of the aqueous solution is (20m ³ -1000m ³ ): 1L. During the specific implementation of the present invention, the liquid flow rate of the absorbent aqueous solution can be controlled to 1L/h, and the gas flow rate of the gas to be treated can be controlled to 20m ³ / h-1000m ³ /h.

In the present invention, the membrane module can be a module composed of multiple membranes and a shell, in which a conventional microporous membrane can be used as a component of the membrane module. The micropores can allow carbon dioxide to pass through the membrane, and the gas can diffuse through the micropores of the membrane. , reacting with an aqueous absorbent solution that meets the above requirements, this process greatly reduces the concentration of carbon dioxide in the gas. In some embodiments, the pore size of the membrane is less than 0.2 μm, and the porosity is 30%-50%.

The membrane of the membrane module of the present invention can be purchased commercially or obtained by conventional methods. The present invention does not limit the membrane raw materials of the membrane module. It can be made from conventional polymer raw materials in this field. In order to avoid the water in the absorbent aqueous solution To enter the environment through a membrane, hydrophobic membrane materials can usually be used.

Under normal circumstances, the selection of membrane materials has a certain impact on the stability and service life of the membrane module. Sufficient mechanical strength, good thermal stability and chemical stability are factors to be considered when selecting membrane materials. Based on the cost and service life of the membrane, Considering properties such as hydrophobicity, in some embodiments, the raw material of the membrane includes at least one of polypropylene, polytetrafluoroethylene, and polyvinylidene fluoride.

In the specific implementation process of the present invention, the gas to be treated is usually introduced on the gas phase side of the membrane module, and the absorbent aqueous solution is introduced on the liquid phase side. The fluids on both sides of the membrane are independent of each other and do not contact each other. Carbon dioxide can escape from the membrane. The gas phase side of the module diffuses through the micropores, diffuses from the gas phase to the membrane-liquid interface, and chemically reacts with the absorbent aqueous solution on the liquid phase side of the membrane module to be removed.

In the present invention, the gas-liquid flow direction may be the same or different. The flow direction of the gas to be treated and the flow direction of the absorbent aqueous solution may flow in the same direction along the membrane. The flow direction of the gas to be treated and the flow direction of the absorbent aqueous solution may be It flows in countercurrent along the membrane.

Normally, the regeneration of carbon dioxide is an endothermic reaction. The absorption liquid formed by absorbing carbon dioxide can regenerate carbon dioxide through the subsequent regeneration process. The aqueous absorbent solution can also be regenerated and reused.

The invention electrolyzes the absorption liquid, uses electrochemical methods to regenerate carbon dioxide, uses electrochemical principles to electrolyze the absorption liquid, can co-produce hydrogen, oxygen and carbon dioxide gas products, combines carbon dioxide regeneration and hydrogen energy production, and reduces Carbon dioxide regeneration energy consumption.

The electrolysis treatment process of the present invention can be carried out in an electrolysis device. The electrolysis device at least includes an electrolytic cell, a cathode area, and an anode area. The cathode area and anode area are both located in the electrolytic cell. The present invention does not make any changes to the electrode materials in the cathode area and anode area. The limit can be selected according to the actual situation. For example, it can be a transition metal oxide and its compound material, a metal alloy material, or a carbon-based composite material.

In the above electrolysis treatment, the absorption liquid is introduced into an electrolytic cell and energized for electrolysis treatment, and the voltage and current of the electrolysis treatment are controlled. During the electrolysis process, carbonate ions, bicarbonate ions and other carbon-containing anions and hydrogen are released into the absorption liquid. Oxygen ions lose electrons, generating a mixed gas of carbon dioxide and oxygen in the anode area, absorbing hydrogen ions in the liquid and gaining electrons, and generating hydrogen gas in the cathode area. After electrolysis treatment, the remaining solution in the electrolytic cell is the electrolysis residual liquid, which can be recycled as an absorbent aqueous solution.

In order to further improve the purity of the regenerated carbon dioxide product gas, it may also include performing low-temperature rectification on the mixed gas of carbon dioxide and oxygen generated in the anode area to achieve separation of carbon dioxide and oxygen, thereby obtaining high-purity carbon dioxide product gas.

In the present invention, a stable voltage is usually used to electrolyze the absorbing liquid to avoid voltage fluctuations and reduce the variation amplitude of the current. The present invention does not limit the voltage of the electrolysis treatment. In some embodiments, the electrolysis conditions of the electrolysis treatment are: the voltage is 1V-8V, such as 1V, 2V, 3V, 4V, 5V, 6V, 7V, 8V or any two of them. range of persons. When the voltage of the electrolysis treatment is low, the electrolysis rate is slow and the regeneration rate of carbon dioxide is slow; if the voltage is high, the electrolysis rate is fast and the regeneration rate of carbon dioxide is fast, making it difficult to collect. Therefore, the appropriate voltage for electrolysis treatment should be selected according to the actual situation.

In some embodiments, a stable current is usually used to electrolyze the absorbing liquid, and the current density of the electrolytic treatment is 2mA/cm ² -3mA/cm ² , such as 2.5mA/cm ² , 2.6mA/cm ² , 2.7mA/cm ² , 2.8mA/cm ² , 2.9mA/cm ² , 3mA/cm ² or a range consisting of any two of them. If the current of the electrolysis treatment is small, the electron flow is small, and the probability of electron transfer is reduced, which is not conducive to the regeneration of carbon dioxide; if the current is large, the plates are prone to heat, affecting the normal operation of the electrolysis device.

In order for the electrolysis treatment process to proceed normally, the temperature during the electrolysis treatment needs to be kept constant at 50°C-80°C. For example, a range consisting of 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or any two thereof. If the temperature is lower, it will cause the electrolysis rate to be slower, increase energy consumption, and affect the electrolysis efficiency; if the temperature is higher, it will cause the evaporation of the solution in the absorption liquid to increase, affecting the electrolysis effect of the absorption liquid.

In the specific implementation process of the present invention, the electrolytic cell can be preheated first, or the absorbing liquid can be preheated, and the preheated absorbing liquid is passed into the electrolytic cell to make the absorption between the anode region and the cathode region The liquid flows; when the space between the anode area and the cathode area in the electrolytic cell is filled with absorption liquid, electricity is applied to set the voltage between the anode area and the cathode area, and the absorption liquid is electrolyzed. It is conducive to the uniform electrolysis of the absorption liquid, is conducive to improving the recovery rate of carbon dioxide, and is conducive to large-scale treatment of the absorption liquid.

In the present invention, the combined application of the above-mentioned membrane absorption method and the electrochemical method can realize large-scale capture of carbon dioxide, and is conducive to increasing the recovery rate of carbon dioxide and reducing energy consumption.

The present invention provides a carbon dioxide capture system for implementing the above carbon dioxide capture method, including:

The absorption unit is equipped with at least one membrane module for absorbing carbon dioxide from the gas to be treated. The gas phase inlet of the absorption unit is used to pass in the gas to be treated, and the liquid phase inlet of the absorption unit is used to pass the gas. into the absorbent aqueous solution;

The regeneration unit is equipped with an electrolysis device for electrolyzing the absorption liquid. The inlet of the regeneration unit is connected with the liquid phase outlet of the absorption unit.

In the present invention, the gas to be treated enters the gas phase side of the membrane module through the gas phase inlet of the absorption unit, and the absorbent aqueous solution enters the liquid phase side of the membrane module through the liquid phase inlet of the absorption unit. When the carbon dioxide capture method is implemented, the membrane module The membrane in the gas can separate the gas to be treated and the absorbent aqueous solution.

The above carbon dioxide capture system also includes a collection tank for gas to be treated, and the collection tank for gas to be treated is used to collect the gas to be treated. The collection tank of the gas to be treated is connected with the gas phase inlet of the absorption unit.

The carbon dioxide capture system also includes a pretreatment device. The pretreatment device is used to pretreat the gas to be treated. The inlet of the pretreatment device is connected to the outlet of the gas collection tank to be treated. The outlet of the pretreatment device is connected to the absorption unit. The gas phase inlets are connected.

In the present invention, when there are multiple membrane modules in the absorption unit, the multiple membrane modules are connected in series, that is, the gas phase outlet of the first membrane module is connected to the gas phase inlet of the second membrane module, and the gas phase outlet of the second membrane module is connected to the gas phase inlet of the second membrane module. The gas phase inlets of the three membrane modules are connected, and so on. Through the connection of multiple membrane modules, the gas to be treated is sequentially passed through the absorption unit composed of multiple membrane modules for absorption processing, so that multi-stage membrane absorption processing of the gas to be processed can be achieved.

In the above embodiment, the gas after absorption treatment is discharged through the gas phase outlet of the absorption unit, and the absorption liquid obtained after absorption treatment is discharged through the liquid phase outlet of the absorption unit.

In the present invention, the regeneration unit at least includes an electrolysis device. The electrolysis device is used to electrolyze the absorption liquid obtained after the membrane absorption treatment. The inlet of the electrolysis device is connected with the liquid phase outlet of the absorption unit. The absorption liquid can be introduced into the electrolytic cell of the electrolysis device through the inlet of the electrolysis device.

In the present invention, the electrolysis device includes a power supply, an electrolytic cell, a cathode area, and an anode area. The cathode area and the anode area are both located in the electrolytic cell. The cathode area and the anode area are respectively equipped with cathode plates and anode plates. The cathode and anode of the device provide DC power. The anode plate is connected to the positive pole of the power supply, and the cathode plate is connected to the negative pole of the power supply.

The above-mentioned electrolysis device is used to electrolyze the absorption liquid. Carbon-containing anions and hydroxide ions such as carbonate ions and bicarbonate ions in the absorption liquid lose electrons and generate a mixture of carbon dioxide and oxygen in the anode area. The absorption liquid The hydrogen ions in the cathode receive electrons and generate hydrogen gas in the cathode region.

In the present invention, in order to improve the regeneration purity of carbon dioxide, a separation unit can also be provided. The separation unit is connected to the gas phase outlet of the anode area of the regeneration unit and is used to separate carbon dioxide in the mixed gas. In the separation unit, cryogenic distillation can be used to separate carbon dioxide and oxygen.

In the above embodiment, a liquid storage device is also included. The liquid storage device is used to temporarily store the absorption liquid. When the amount of absorption liquid in the liquid storage device meets a certain volume, the absorption liquid flows to the electrolysis device.

In the above embodiment, a gas storage tank is also included. The gas storage tank is used to temporarily contain the gas generated by electrolysis, including a hydrogen gas storage tank and a mixed gas gas storage tank. The mixed gas storage tank is connected to the anode area of the electrolysis device, and the hydrogen gas storage tank is connected to the cathode area of the electrolysis device.

In the specific implementation process of the present invention, a lean liquid tank may also be included. The electrolysis residual liquid is discharged from the liquid phase outlet of the electrolysis device and can flow to the lean liquid tank. The lean liquid tank can be connected to the liquid inlet of the membrane module, so that the electrolysis residual liquid The liquid can be returned to the absorption unit for recycling.

It should be noted that the connection in the present invention can be pipe connection.

In order to control the gas flow and liquid flow, the carbon dioxide capture system of the present invention can also include a flow control device. The flow control device includes a gas flow control device and a liquid flow control device, wherein the gas flow control device is located at the rear end of the pretreatment device. , the back end of the gas flow control device is connected to the gas phase inlet of the absorption unit.

In the above embodiment, the valve can be set to adjust and control the flow control device in real time based on the data obtained through monitoring.

The carbon dioxide capture system of the present invention may also include a gas component analysis device, which is provided in the gas phase outlet section of the absorption unit and is used to analyze the components of the exhaust gas at the gas phase outlet.

In the present invention, the above carbon dioxide capture system is used to implement the carbon dioxide capture method. The specific process steps are as follows:

Step 1: The gas to be treated is pretreated by the pretreatment device;

Step 2: Make the pretreated gas obtained in Step 1 adjust the flow rate through the gas flow control device and then send it to the gas phase side of the membrane module through the gas phase inlet of the absorption unit, and send the absorbent aqueous solution into the membrane through the liquid phase inlet of the absorption unit. On the liquid phase side of the component, the two phases absorb carbon dioxide in a parallel counter-current manner. After the absorption treatment, the absorption liquid and the absorbed gas are obtained;

Step 3: The absorption liquid obtained after the reaction flows out from the liquid phase outlet of the absorption unit, and the tail gas after absorption treatment flows out from the gas phase outlet of the absorption unit. The tail gas is analyzed for its components, and the tail gas is discharged into the atmosphere after being tested to meet the standards;

Step 4: Let the absorption liquid enter the electrolysis device of the regeneration unit for electrolysis treatment. Use a gas collection tank to collect the gas in the cathode area and anode area of the electrolysis unit. In the anode area, use a gas storage tank to collect the mixed gas of carbon dioxide and oxygen. At the cathode, Hydrogen is collected in the area; a lean liquid tank is used to collect the electrolysis residual liquid after electrolysis treatment.

In the above embodiment, the gas to be treated and the absorbent aqueous solution can be introduced into the absorption unit by means of pump pressure.

In order to further improve the purity of carbon dioxide, the present invention also includes performing low-temperature rectification on the mixed gas collected in step 4, and utilizing the different boiling points of carbon dioxide and oxygen to achieve separation of carbon dioxide and oxygen. Through low-temperature distillation, carbon dioxide products with a purity of over 99% can be obtained.

The carbon dioxide capture system provided by the invention has a simple structure, is convenient and quick to use, and can be used to capture carbon dioxide in the gas to be processed. It is especially suitable for capturing carbon dioxide in the air, further reducing the carbon dioxide content in the air, and achieving large-scale carbon emission reduction. . In addition, the treatment system is also equipped with a regeneration unit. The regeneration unit can be used in conjunction with the electrolytic hydrogen production process, which can significantly reduce the energy consumption of carbon dioxide regeneration. It will also reduce the operating cost of the carbon dioxide capture system, which is conducive to large-scale promotion and application. .

In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the implementation of the present invention. examples, not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1

The carbon dioxide capture system of this embodiment includes:

The absorption unit is used to absorb carbon dioxide from the gas to be treated. The absorption unit is provided with at least one membrane module. The gas phase inlet of the absorption unit is used to introduce the gas to be processed, and the liquid phase inlet of the absorption unit is used to introduce the absorbent. Aqueous solution, in which the raw material of the membrane in the membrane module is polypropylene, the pore size of the membrane is 0.1 μm, and the porosity is 30%;

A regeneration unit. An electrolysis device is provided in the regeneration unit for electrolyzing the absorption liquid. The inlet of the regeneration unit is connected with the liquid phase outlet of the absorption unit;

A separation unit is used to separate carbon dioxide, and the inlet of the separation unit is connected with the gas phase outlet of the regeneration unit;

Power supply, which provides DC power to the cathode and anode of the electrolysis device.

The carbon dioxide capture method of this embodiment is carried out in the above-mentioned treatment system, as shown in the flow chart in Figure 1, including:

The air is passed into the gas phase side of the membrane module through the gas phase inlet of the absorption unit at a flow rate of ^1000m3 /h, and the 60wt% KOH solution is passed into the liquid phase of the membrane module through the liquid phase inlet of the absorption unit at a flow rate of 1L/h. On one side, carbon dioxide is absorbed and treated to obtain an absorption liquid;

The absorption liquid enters the electrolysis device of the regeneration unit through pipeline b. The temperature is controlled to 50°C and the current density is 2mA/cm ² to perform electrolysis treatment. The mixed gas of carbon dioxide and oxygen is collected in the anode area of the electrolysis device and is collected at the cathode. Pure hydrogen is collected in the zone, and the molar content of carbon dioxide in the mixed gas is analyzed to be 66.7%; the residual liquid after electrolysis can be returned to the absorption unit of the membrane module through pipeline a for recycling;

The mixed gas is passed into the separation unit, pressurized to 2MPa, then cooled to -15°C and entered into a low-temperature rectification tower for low-temperature rectification to obtain a carbon dioxide product gas with a concentration of more than 99%.

Example 2

The carbon dioxide capture system of this embodiment includes:

The absorption unit is used to absorb carbon dioxide from the gas to be treated. The absorption unit is provided with at least one membrane module. The gas phase inlet of the absorption unit is used to introduce the gas to be processed, and the liquid phase inlet of the absorption unit is used to introduce the absorbent. Aqueous solution, in which the raw material of the membrane in the membrane module is polytetrafluoroethylene, the pore size of the membrane is 0.05 μm, and the porosity is 40%;

A regeneration unit. An electrolysis device is provided in the regeneration unit for electrolyzing the absorption liquid. The inlet of the regeneration unit is connected with the liquid phase outlet of the absorption unit;

A separation unit is used to separate carbon dioxide, and the inlet of the separation unit is connected with the gas phase outlet of the regeneration unit;

Power supply, which provides DC power to the cathode and anode of the electrolysis device.

The carbon dioxide capture method of this embodiment is carried out in the above-mentioned treatment system, as shown in the flow chart in Figure 1, including:

Let air flow into the gas phase side of the membrane module through the gas phase inlet of the absorption unit at a flow rate of 100m ³ /h, and at the same time, 35% 2-amino-2-methyl-1-propanol (AMP) solution is added at 1L/h. The flow is passed through the liquid phase inlet of the absorption unit into the liquid phase side of the membrane module, where carbon dioxide is absorbed and processed to obtain the absorption liquid;

The absorption liquid enters the electrolysis device of the regeneration unit through pipeline b. The temperature is controlled to 60°C and the current density is 2.5mA/cm ² . Electrolysis is performed. The mixed gas of carbon dioxide and oxygen is collected in the anode area of the electrolysis device. Pure hydrogen is collected in the cathode area, and the molar content of carbon dioxide in the mixed gas is analyzed to be 66.7%; the residual liquid after electrolysis can be returned to the absorption unit of the membrane module through pipeline a for recycling;

The mixed gas is passed into the separation unit, pressurized to 2MPa, then cooled to -15°C and entered into a low-temperature rectification tower for low-temperature rectification to obtain a carbon dioxide product gas with a concentration of more than 99%.

Example 3

The carbon dioxide capture system of this embodiment includes:

The absorption unit is used to absorb carbon dioxide from the gas to be treated. The absorption unit is provided with at least one membrane module. The gas phase inlet of the absorption unit is used to introduce the gas to be processed, and the liquid phase inlet of the absorption unit is used to introduce the absorbent. Aqueous solution, in which the raw material of the membrane in the membrane module is polyvinylidene fluoride, the pore size of the membrane is 0.01 μm, and the porosity is 50%;

A regeneration unit. An electrolysis device is provided in the regeneration unit for electrolyzing the absorption liquid. The inlet of the regeneration unit is connected with the liquid phase outlet of the absorption unit;

A separation unit is used to separate carbon dioxide, and the inlet of the separation unit is connected with the gas phase outlet of the regeneration unit;

Power supply, which provides DC power to the cathode and anode of the electrolysis device.

The carbon dioxide capture method of this embodiment is carried out in the above-mentioned treatment system, as shown in the flow chart in Figure 1, including:

The air is passed into the gas phase side of the membrane module through the gas phase inlet of the absorption unit at a flow rate of ^20m3 /h, and at the same time, a 10wt% potassium glycinate solution is passed into the liquid phase of the membrane module through the liquid phase inlet of the absorption unit at a flow rate of 1L/h. On the phase side, carbon dioxide is absorbed and treated to obtain an absorption liquid;

The absorption liquid enters the electrolysis device of the regeneration unit through pipeline b. The temperature is controlled to 80°C and the current density is 3mA/cm ² to perform electrolysis treatment. The mixed gas of carbon dioxide and oxygen is collected in the anode area of the electrolysis device and is collected at the cathode. Pure hydrogen is collected in the zone, and the molar content of carbon dioxide in the mixed gas is analyzed to be 66.7%; the residual liquid after electrolysis can be returned to the absorption unit of the membrane module through pipeline a for recycling;

The mixed gas is passed into the separation unit, pressurized to 2MPa, then cooled to -15°C and entered into a low-temperature rectification tower for low-temperature rectification to obtain a carbon dioxide product gas with a concentration of more than 99%.

The carbon dioxide capture method and system provided by the present invention can effectively capture and recover carbon dioxide in the gas to be processed, can be used in conjunction with the electrolytic hydrogen production process, significantly reduce energy consumption and operating costs, and are conducive to large-scale promotion and application.

The preferred embodiments and experimental verifications of the present invention are described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, any technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention and on the basis of the prior art should be within the scope of protection determined by the claims.

Claims (10)

1. A carbon dioxide capture method, characterized in that it includes the following steps: (1) The gas to be treated passes through the membrane module and then enters the absorbent aqueous solution to absorb carbon dioxide to obtain an absorption liquid; (2) Perform electrolysis treatment on the absorption liquid to obtain carbon dioxide. 2. The carbon dioxide capture method according to claim 1, characterized in that the absorbent aqueous solution is an alkaline aqueous solution. 3. The method of capturing carbon dioxide according to claim 1, wherein the absorbent includes at least one of alkaline inorganic substances and nitrogen-containing organic substances; The nitrogen-containing organic matter includes at least one of amino acid salts and organic alcohol amines. 4. The carbon dioxide capture method according to any one of claims 1 to 3, characterized in that the mass concentration of the absorbent in the absorbent aqueous solution is 10wt%-60wt%. 5. The carbon dioxide capture method according to any one of claims 1 ^to 4, characterized in that the gas-liquid ratio of the gas to be treated and the absorbent aqueous solution is ( ^20m3-1000m3 ): 1L. 6. The carbon dioxide capture method according to any one of claims 1-5, characterized in that the pore diameter of the membrane is 0.2 μm or less, and the porosity is 30%-50%. 7. The carbon dioxide capture method according to any one of claims 1 to 6, characterized in that the raw material of the membrane includes at least one of polypropylene, polytetrafluoroethylene, and polyvinylidene fluoride. 8. The carbon dioxide capture method according to any one of claims 1 to 7, characterized in that the electrolysis conditions of the electrolysis treatment are: current density is 2mA/cm ² -3mA/cm ² , and temperature is 50°C - 80℃. 9. A carbon dioxide capture system, characterized in that it is used to implement the carbon dioxide capture method according to any one of claims 1 to 8, including: The absorption unit is used for absorbing carbon dioxide from the gas to be processed. At least one membrane module is provided in the absorption unit. The gas phase inlet of the absorption unit is used to introduce the gas to be processed. The liquid phase inlet of the absorption unit is used for To pass in the absorbent aqueous solution; A regeneration unit is provided with an electrolysis device for electrolyzing the absorption liquid. The inlet of the regeneration unit is connected to the liquid phase outlet of the absorption unit. 10. The system according to claim 9, further comprising a separation unit for separating carbon dioxide, the inlet of the separation unit being connected to the gas phase outlet of the regeneration unit; and/or, A power supply is also included to provide direct current power to the cathode and anode of the electrolysis device.