Method and apparatus for direct capture of co2 from air using a cooling tower

Abstract

The application discloses a device for directly capturing CO2 in air by using a cooling tower, comprising a CO2 capturing module and an electrolytic CO2 releasing and capture liquid regeneration module; the CO2 capturing module comprises a circulating water cooling tower and a heat exchange system, the circulating water cooling tower is used for capturing CO2 in air, and the heat exchange system is a circulating water system serving the circulating water cooling tower; the electrolytic CO2 releasing and capture liquid regeneration module comprises a three-chamber electrolytic cell, an acidification chamber accessory assembly, a cathode chamber accessory assembly, an electrolyte input assembly, an external hydrogen inlet and outlet assembly and a power supply device. The device has the following advantages: on the basis of realizing the cooling circulating water function of the cooling tower, the existing circulating water cooling tower is directly used as an air contactor to realize direct air capture of CO2.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of directly capturing carbon dioxide in the air, in particular to a method and device for directly capturing CO2 in the air by using a cooling tower. BACKGROUND

[0002] Carbon capture and storage (CCUS) refers to removing CO2 from the atmosphere through various methods and storing it in the ground or other media to reduce its impact on climate change. The current main CO2 capture technology includes absorption and adsorption, which is basically aimed at power generation, steel, cement and other industries, and belongs to point source CO2 capture. When facing CO2 generated by mobile sources such as cars, planes and living organisms, this mode is not powerful enough. In essence, these existing capture methods are limited by factors such as location and process, and can only reduce the emission of point source CO2, and cannot effectively remove the CO2 already produced in the atmosphere, which belongs to the category of "carbon emission reduction".

[0003] Currently, developing new technologies to directly capture CO2 from the air (DAC) is an effective method to overcome the shortcomings of the traditional point source carbon capture mode, which is also a "carbon sink" mode different from "carbon emission reduction", and has important significance in reducing the concentration of CO2 in the global atmosphere. DAC can be used with other negative carbon emission technologies to reduce CO2 emissions from various sources, including mobile and dispersed emission sources.

[0004] Air contactor is one of the cores of direct air capture technology, and it is an important equipment to ensure CO2 capture. Compared with flue gas capture, the CO2 content in the air is lower, which means that the amount of CO2 contacted by the two is nearly 380 times different in the same time. Therefore, from the engineering point of view, in order to maintain a large amount of CO2 capture, the air contactor cannot be effectively controlled in volume and quantity. This large facility that needs to be built additionally consumes a lot of resources and has a long cost recovery period, which is one of the important reasons restricting the development of DAC technology.

[0005] Absorption is a technology that uses a chemical absorbent to absorb CO2 in the air into a liquid for processing and storage, and CO2 is fixed into a CO2-rich liquid in the absorbent aqueous solution. Subsequently, the CO2-rich liquid will enter the corresponding resolving device to release CO2. However, the current resolving process generally has some deficiencies, mainly in the aspect of energy consumption. Taking the mono-amine process as an example, the resolving CO2 needs to be carried out at 80-120 DEG C; and the process represented by potassium hydroxide and other inorganic alkali absorbents needs to go through a high-temperature calcination process to obtain CO2, and the calcination temperature is generally above 900 DEG C. In addition, both of these two typical processes need to build large-scale resolving equipment, such as a resolving tower, a calcium hydroxide (Ca(OH)2) precipitation process supporting facility, a calcining furnace, etc., which has a large floor area and high cost. SUMMARY

[0006] The technical problem solved by the present application is to provide a method and device for directly capturing CO2 in air by using a cooling tower to realize the following purposes:

[0007] 1. On the basis of realizing the cooling tower cooling circulating water function, the existing circulating water cooling tower is directly used as an air contactor to realize direct air capture CO2;

[0008] 2. The carbon dioxide can be captured and released at room temperature, and the capture liquid can be regenerated, which can avoid the problem that the conventional CO2 release method needs to be heated and conflicts with the basic function (cooling circulating water) of the circulating water cooling tower; and the capture reagent can be recycled, the cost investment of the reagent is maximized, and good economic benefits are obtained.

[0009] To solve the above technical problems, the present application adopts the following technical solutions:

[0010] The device for directly capturing CO2 in air by using a cooling tower comprises a CO2 capture module and an electrolytic CO2 release and capture liquid regeneration module;

[0011] The CO2 capture module comprises a circulating water cooling tower and a heat exchange system, and the circulating water cooling tower is used for capturing CO2 in air, and the heat exchange system is a circulating water system served by the circulating water cooling tower;

[0012] The electrolytic CO2 release and capture liquid regeneration module comprises a three-chamber electrolytic cell, an acidification chamber accessory assembly, a cathode chamber accessory assembly, an electrolyte input assembly, an external hydrogen inlet and outlet assembly and a power supply device;

[0013] The three-chamber electrolytic cell comprises an anode chamber, an acidification chamber and a cathode chamber, the inlet of the acidification chamber is connected with the electrolyte input assembly, and the power supply device is connected with the acidification chamber and the cathode chamber;

[0014] The acidification chamber accessory assembly comprises an acidification gas-liquid buffer tank, which is connected to the outlet of the acidification chamber through a first gas-liquid mixing pipeline and is connected to the inlet of the cathode chamber through a liquid outlet pipeline.

[0015] The cathode chamber accessory assembly comprises a cathode gas-liquid buffer tank, which is connected to the outlet of the cathode chamber through a second gas-liquid mixing pipeline and is connected to one inlet of the anode chamber through a gas conveying pipeline.

[0016] The external hydrogen inlet and outlet assembly comprises an external hydrogen inlet pipeline and a hydrogen outlet pipeline, wherein the external hydrogen inlet pipeline is connected to the inlet of the anode chamber, and the hydrogen outlet pipeline is connected to the outlet of the anode chamber.

[0017] Further, the circulating water cooling tower comprises a cooling tower body, which is internally provided with, from bottom to top, a water collecting pool, a filler layer, a spraying system and a fan, wherein the water collecting pool is arranged below the filler layer, and the spraying system is arranged above the filler layer; and the fan is arranged at the top air outlet of the tower body.

[0018] The cooling tower body is provided with a cooling tower air inlet, which is arranged between the spraying system and the water collecting pool.

[0019] The heat exchange system is connected to the spraying system and the water collecting pool through pipelines; and a delivery centrifugal pump is arranged on the pipeline between the heat exchange system and the water collecting pool.

[0020] Further, the acidification chamber is arranged between the cathode chamber and the anode chamber, a cathode chamber membrane electrode is arranged between the acidification chamber and the cathode chamber, and functions to reduce water to generate hydrogen and hydroxyl; and an anode chamber membrane electrode is arranged between the acidification chamber and the anode chamber, and functions to oxidize hydrogen to provide protons to the acidification chamber.

[0021] Further, the acidification gas-liquid buffer tank is connected to a gas discharge pipeline for delivering CO2, and a gas control valve is arranged on the gas discharge pipeline for adjusting gas output; and a first liquid control valve is arranged on the liquid outlet pipeline.

[0022] Further, the acidification chamber accessory assembly further comprises a first pressure detector, which is a pressure sensor and is used for monitoring the pressure in the acidification gas-liquid buffer tank and the acidification chamber; and the first pressure detector is arranged at the upper portion of the acidification gas-liquid buffer tank.

[0023] The first pressure detector is electrically connected to the gas control valve.

[0024] Further, the cathode gas-liquid buffer tank is connected to a regenerated liquid discharge pipeline, the regenerated liquid discharge pipeline is connected to a CO2 capture module, a second liquid control valve is arranged between the regenerated liquid discharge pipeline and the CO2 capture module; and a second pressure detector is arranged at the top of the cathode gas-liquid buffer tank.

[0025] Further, the electrolyte input assembly includes an electrolyte input pipeline connected to the inlet of the acidification chamber and the CO2 capture module, and the electrolyte input pipeline is provided with a flow meter, a liquid inlet valve, a centrifugal pump, and a PH detector.

[0026] The method for directly capturing CO2 in air by using a cooling tower includes a CO2 capture method and an electrolytic desorption CO2 and capture liquid regeneration method.

[0027] The CO2 capture method includes the following steps:

[0028] Step 1: Turn on the delivery centrifugal pump, and after the CO2 capture liquid flows through the heat exchange system, it is sprayed through the spraying system and flows from top to bottom through the filler layer under the action of gravity; at the same time, turn on the fan, and air enters the cooling tower body from the cooling tower inlet and flows from bottom to top through the filler layer;

[0029] Step 2: The air flow and the CO2 capture liquid flow are in full contact in the filler layer, and the CO2 in the air is captured; after repeating this process for 12-48 hours, the absorbent aqueous solution basically reaches a saturated state of capture;

[0030] Step 3: After the capture reaction process continues for 48 hours, 10 mL of samples are taken at 0, 2, 4, 6, 12, 24, 36, and 48 hours, respectively, and the pH and CO2 loading of the samples are measured by using a PH detector and an ion chromatograph, respectively; one of the CO2 loading and the PH value can be used to judge whether the absorbent aqueous solution is saturated.

[0031] According to different concentrations of the absorbent aqueous solution, the CO2 loading after saturation is different.

[0032] The electrolytic desorption CO2 and capture liquid regeneration method includes the following steps:

[0033] Step 4: The CO2-saturated capture liquid is delivered to the three-chamber electrolytic cell

[0034] When the PH detector detects that the pH is less than or equal to 9.40, the CO2-saturated capture liquid is sequentially delivered and filled into the acidification chamber and the cathode chamber, after the two chambers are filled, the saturated absorbent aqueous solution flows into the acidification gas-liquid buffer tank and passes through the liquid outlet thereof;

[0035] After the acidification chamber and the cathode chamber are filled with liquid, the liquid supply is temporarily stopped;

[0036] Step 5: Other gases in the anode chamber and the cathode gas-liquid buffer tank are discharged, and hydrogen gas is filled;

[0037] Step 6: Electrolytic reaction

[0038] After the hydrogen tank is filled, the valve between the cathode gas-liquid buffer tank and the CO2 capture module is closed, and the hydrogen supply is stopped. The power supply is turned on, and the electrolysis reaction begins. After 1-3 minutes of electrolysis, the electrolyte input assembly resumes electrolyte supply;

[0039] Step 6.1, anode chamber reaction

[0040] Oxidation reaction occurs in the anode chamber, and H2 is oxidized to generate protons;

[0041] The reaction is as follows:

[0042] H2-2e - →2H + ;

[0043] Step 6.2, acidification chamber reaction

[0044] Protons in the anode chamber pass through the anode membrane electrode into the acidification chamber and react with the capture solution saturated with carbon dioxide. The gas product is carbon dioxide, and the liquid product is the capture solution after releasing CO2;

[0045] The reaction products in the acidification chamber flow into the acidification gas-liquid buffer tank. When the pressure in the acidification gas-liquid buffer tank is ≥130 kPa, CO2 is output and collected. When the pressure is less than this value, CO2 output is stopped and the pressure is waited to rise. The capture solution after releasing CO2 enters the cathode chamber for regeneration;

[0046] The composition of the gas product is detected every 20 minutes after the reaction starts. As the reaction proceeds, the purity of CO2 gradually increases, and the final product CO2 purity is ≥98%;

[0047] Step 6.3, cathode chamber reaction

[0048] Reduction reaction occurs in the cathode chamber to generate hydroxide and hydrogen. Hydrogen is transported to the anode chamber for oxidation again, realizing the recycling of hydrogen. Hydroxide combines with the lean solution and reacts to achieve regeneration, obtaining regenerated capture solution with capture ability;

[0049] H2 and regenerated capture solution flow into the cathode gas-liquid buffer tank together. When the pressure in the cathode gas-liquid buffer tank is ≥130 kPa, hydrogen is transported to the anode chamber under the action of pressure;

[0050] The reduction reaction is as follows:

[0051] 4H2O+4e - →4OH - +2H2.

[0052] Further, the CO2 capture liquid is a buffer type capture liquid with pH=10.00, and the absorbent solution is formed by an absorbent and cooling tower circulating water, wherein the absorbent is a mixture of glycine, sodium hydroxide and sodium chloride; the concentration of the CO2 capture liquid is 1-3 mol / L; wherein the concentration of glycine is 0.25-3.00 mol / L; the concentration of sodium hydroxide is 0.15-1.50 mol / L; and the concentration of sodium chloride is 0.50 mol / L.

[0053] Further, in the case that the CO2 capture liquid is initially pH=10.00, the preferred absorbent solution ratio is specifically as follows:

[0054] The concentration of glycine is 3.00 mol / L, the concentration of sodium hydroxide is 1.50 mol / L, the concentration of sodium chloride is 0.50 mol / L, and the initial pH is 10.00; after the CO2 capture liquid captures carbon dioxide in the air to saturation, the pH is approximately 9.35, and the capture amount of CO2 is 0.47 mol / L.

[0055] Compared with the prior art, the above technical scheme has the following technical effects:

[0056] 1. On the basis of realizing the cooling tower circulating water cooling function, the existing circulating water cooling tower is directly used as an air contactor to realize direct air capture of CO2.

[0057] 2. The carbon dioxide is captured and released at normal temperature, and the electrochemical method is used to release CO2 at normal temperature, so that the problem of conflicting with the basic function (cooling circulating water) of the circulating water cooling tower caused by the need for repeated heating of water body in the conventional CO2 release method can be avoided, and the recycling of the capture reagent can be realized to maximize the reduction of reagent cost investment and achieve good economic benefits.

[0058] 3. The problem of hydrogen production at the cathode in the conventional electrolytic CO2 release technology is solved, so that the hydrogen is utilized at the anode to effectively reduce the safety hidden danger in the production process.

[0059] 4. The problem of low purity of carbon dioxide caused by the generation of oxygen at the anode chamber in the prior art is avoided, and the purity of CO2 can be greatly improved, and the purity of CO2 is ≥98%.

[0060] 5. The energy consumption is low, and the CO2 release efficiency is high, and the CO2 release efficiency is ≥95.

[0061] 6. Clean energy such as wind power generation, photovoltaic power generation and tidal power generation can be used, and good economic benefits can be achieved.

[0062] 7、The CO2 capture liquid has a low initial pH value under the premise of maintaining a high CO2 load, and can be applied to most scenes with strict pH restrictions. Meanwhile, the CO2 capture liquid is a sodium glycine buffer solution, which is green, efficient and non-toxic. The CO2 capture liquid is a buffer type capture liquid, which can maintain a low pH value and has a high CO2 load, and is suitable for the pH requirements of the normal operation of the cooling tower system. On the basis of ensuring the cooling function of the circulating water cooling tower, the circulating water cooling tower can be directly used as an air contactor to capture CO2 in the air. BRIEF DESCRIPTION OF DRAWINGS

[0063] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings required to be used in the specific embodiments or prior art description will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual proportion.

[0064] Figure 1 FIG. 1 is a structural schematic diagram of a device for directly capturing CO2 in the air by using a cooling tower in the present application. DETAILED DESCRIPTION

[0065] As shown in FIG. 1, the device for directly capturing CO2 in the air by using a cooling tower comprises a CO2 capture module and an electrolysis CO2 release and capture liquid regeneration module. Figure 1

[0066] The CO2 capture module comprises a circulating water cooling tower and a heat exchange system 7.

[0067] The circulating water cooling tower is used for capturing CO2 in the air, and comprises a cooling tower body 1, wherein a water collecting pool 2, a filler layer 3, a spraying system 4 and a fan 5 are arranged in the cooling tower body 1 from bottom to top. The water collecting pool 2 is arranged below the filler layer 3, and the spraying system 4 is arranged above the filler layer 3. The fan 5 is arranged at the top of the tower body.

[0068] A cooling tower air inlet is arranged on the cooling tower body 1, and is arranged between the spraying system and the water collecting pool. The filler layer has a good gas-liquid exchange function, which promotes carbon dioxide capture and circulating water cooling.

[0069] The heat exchange system 7 is a circulating water system served by the circulating water cooling tower. The cooling tower body 1 cools the circulating water in the heat exchange system. The heat exchange system 7 is connected with the spraying system 4 and the water collecting pool 2 through pipelines. A delivery centrifugal pump 6 is arranged on the pipeline between the heat exchange system 7 and the water collecting pool 2.

[0070] The electrolysis CO2 release and capture liquid regeneration module comprises a three-chamber electrolytic cell, an acidification chamber accessory assembly, a cathode chamber accessory assembly, an electrolyte input assembly, an external hydrogen inlet and outlet assembly and a power supply device.​

[0071] The three-chamber electrolytic cell comprises an anode chamber 12 for an anodic oxidation reaction, a cathode chamber 16 for a cathodic reduction reaction, and an acidification chamber 14 for a carbon dioxide releasing reaction. The acidification chamber 14 is arranged between the cathode chamber 16 and the anode chamber 12, a cathode chamber membrane electrode 15 is arranged between the acidification chamber 14 and the cathode chamber 16, and the cathode chamber membrane electrode 15 functions to reduce water to produce hydrogen and hydroxyl; an anode chamber membrane electrode 13 is arranged between the acidification chamber 14 and the anode chamber 12, and the anode chamber membrane electrode 13 functions to oxidize hydrogen to provide protons to the acidification chamber 14.

[0072] The inlet of the acidification chamber 14 is connected to an electrolyte input assembly, the outlet of the acidification chamber 14 and the inlet of the cathode chamber 16 are connected to an acidification chamber auxiliary assembly, and the outlet of the cathode chamber 16 is connected to a cathode chamber auxiliary assembly; the anode chamber 12 has two inlets, one of which is connected to the cathode chamber auxiliary assembly, and the other of which is connected to the gas inlet part of an external hydrogen inlet and outlet assembly, and the outlet of the anode chamber 12 is connected to the gas outlet part of the external hydrogen inlet and outlet assembly.

[0073] The acidification chamber auxiliary assembly separates the liquid products of the acidification chamber 14 and outputs the gas products, and further flows the liquid products into the cathode chamber 16 to fill it; the acidification chamber auxiliary assembly comprises an acidification gas-liquid buffer tank 17 and a first pressure detector 18; the acidification gas-liquid buffer tank 17 is used to separate the outflow products in the acidification chamber; the first pressure detector 18 is a pressure sensor used to monitor the pressure in the acidification gas-liquid buffer tank and the acidification chamber, and the first pressure detector 18 is arranged at the upper part of the acidification gas-liquid buffer tank 17.

[0074] The acidification gas-liquid buffer tank 17 is connected to the outlet of the acidification chamber 14 through a first gas-liquid mixing pipeline 31, and the acidification gas-liquid buffer tank 17 is connected to the inlet of the cathode chamber 16 through a liquid outlet pipeline 32, and the liquid outlet pipeline 32 is provided with a first liquid control valve 20.

[0075] The acidification gas-liquid buffer tank 17 is further connected to a gas discharge pipeline 33 for transporting CO2, and the gas discharge pipeline 33 is provided with a gas control valve 19 for adjusting the gas output.

[0076] The first pressure detector 18 is electrically connected to the gas control valve 19, used to monitor and adjust the pressure in the acidification gas-liquid buffer tank in real time, and control the output flow of the gas products; when the pressure in the acidification gas-liquid buffer tank is greater than or equal to 130 kPa, the gas control valve is opened to start transporting CO2, and when the pressure is less than the value, the gas control valve is closed to wait for the pressure to rise.

[0077] The cathode chamber accessory assembly is used for inputting hydrogen into the anode chamber and discharging the regeneration liquid into the CO2 capture module. The cathode chamber accessory assembly comprises a cathode gas-liquid buffer tank 21 and a second pressure detector 22. The cathode gas-liquid buffer tank 21 is used for separating the cathode chamber 16 outflow product. The second pressure detector 22 is a pressure sensor used for monitoring the pressure in the cathode gas-liquid buffer tank 21 and the anode chamber 12. The second pressure detector 22 is arranged at the top of the cathode gas-liquid buffer tank 21.

[0078] The cathode gas-liquid buffer tank 21 is connected with the outlet of the cathode chamber 16 through a second gas-liquid mixing pipeline 34. The cathode gas-liquid buffer tank 21 is connected with an inlet of the anode chamber 12 through a gas conveying pipeline 35. The cathode gas-liquid buffer tank 21 is connected with a regeneration liquid discharge pipeline 36. The second liquid control valve 24 is arranged on the regeneration liquid discharge pipeline 36.

[0079] The electrolyte input assembly comprises an electrolyte input pipeline 37 connected with the inlet of the acidification chamber 14 and the CO2 capture module. The electrolyte input pipeline 37 is provided with a flow meter 11, an inlet valve 10, a centrifugal pump 9 and a pH detector 8. The pH detector 8 is arranged between the water collecting pool 2 and the centrifugal pump 9 and used for detecting the pH of the absorbent water solution to determine whether it reaches the saturation state. The inlet valve and the flow meter are electrically connected and used for synchronously controlling the liquid input and the flow.

[0080] The external hydrogen input and output assembly comprises an external hydrogen input pipeline 39 and a hydrogen output pipeline 38. The external hydrogen input pipeline 39 is connected with the inlet of the anode chamber 12. The hydrogen output pipeline 38 is connected with the outlet of the anode chamber 12. The external hydrogen input pipeline 39 is provided with a gas flow meter and an inlet valve 26 used for adjusting the external hydrogen input flow and controlling the external hydrogen input, respectively. The hydrogen output pipeline 38 is provided with an outlet valve 23.

[0081] Before the three-chamber electrolytic cell starts the electrolysis reaction to release CO2, the external hydrogen input and output assembly inputs hydrogen and discharges other gases in the anode chamber to make it full of hydrogen.

[0082] The power supply device comprises a power converter and a power system. The power converter is used for converting alternating current into direct current. The power system includes, but is not limited to, wind power, photovoltaic power, tidal power, nuclear power and conventional power. The power converter is connected with the power system and the cathode chamber 16 and the anode chamber 12.

[0083] The method for directly capturing CO2 in air by using a cooling tower comprises a CO2 capture method and an electrolytic desorption CO2 and capture liquid regeneration method.

[0084] The CO2 capture method comprises the following steps:

[0085] Step 1, open the delivery centrifugal pump, after the CO2 capture liquid flows through the heat exchange system, it is sprayed through the spraying system, and flows from top to bottom through the filler layer under the action of gravity; at the same time, open the fan, and air enters the cooling tower body from the cooling tower inlet and flows from bottom to top through the filler layer.

[0086] Step 2, the air flow and the CO2 capture liquid flow are fully contacted in the filler layer to capture CO2 in the air; after repeating the process for 12-48 hours, the absorbent aqueous solution has basically reached the capture saturation state.

[0087] Step 3, after the capture reaction process continues for 48 hours, 10 mL of samples are taken at 0, 2, 4, 6, 12, 24, 36, and 48 hours, respectively, and the pH and CO2 load of the samples are measured by using a pH detector and an ion chromatograph, respectively; one of the CO2 load and the pH value satisfies to judge that the absorbent aqueous solution is saturated.

[0088] According to the different concentrations of the absorbent aqueous solution, the CO2 load after saturation is different.

[0089] The electrolytic desorption CO2 and capture liquid regeneration method comprises the following steps:

[0090] Step 4, the CO2 saturated capture liquid is transported to the electrolytic cell

[0091] When the pH detector detects that the pH is less than or equal to 9.40, the liquid inlet valve on the electrolyte input pipeline is opened, and the CO2 saturated capture liquid (rich liquid) is transported and filled into the acidification chamber and the cathode chamber in turn by the centrifugal pump, after the two chambers are filled, the saturated absorbent aqueous solution flows into the acidification gas-liquid buffer tank and passes over the liquid outlet thereof;

[0092] After the acidification chamber and the cathode chamber are filled with liquid, the liquid inlet valve on the electrolyte input pipeline is closed, and the liquid supply is suspended.

[0093] Step 5, other gases in the anode chamber and the cathode gas-liquid buffer tank are discharged, and hydrogen gas is filled;

[0094] Step 5.1, open the gas inlet valve on the external hydrogen gas input pipeline to input external hydrogen gas into the anode chamber, fill the anode chamber with hydrogen gas, open the gas outlet valve on the hydrogen gas output pipeline, and discharge the excess hydrogen gas from the outlet connected thereto; the process lasts for 1-10 minutes.

[0095] Step 5.2, open the second liquid control valve between the cathode gas-liquid buffer tank and the CO2 capture module, close the gas outlet valve on the hydrogen gas output pipeline, and hydrogen gas will enter the cathode gas-liquid buffer tank to discharge other gases in the cathode gas-liquid buffer tank, and the process lasts for 1-10 minutes.

[0096] The cathode gas-liquid buffer tank has a certain amount of electrolyte in the process of inputting hydrogen, and the electrolyte level of the part is higher than the outlet of the cathode gas-liquid buffer tank, so as to prevent hydrogen from overflowing from the outlet.

[0097] Step 6, electrolysis reaction

[0098] After the hydrogen is filled, the second liquid control valve between the cathode gas-liquid buffer tank and the CO2 capture module, and the inlet valve on the external hydrogen input pipeline are closed; the power supply is turned on, and the electrolysis reaction starts; after electrolysis for 1-3 minutes, the valve on the electrolyte input assembly is opened, and the electrolyte supply is restored.

[0099] Step 6.1, anode chamber reaction

[0100] The anode chamber generates an oxidation reaction, and H2 is oxidized to generate protons;

[0101] The reaction formula is as follows:

[0102] H2-2e - →2H + ;

[0103] Step 6.2 acidification chamber reaction (release CO2)

[0104] The protons in the anode chamber enter the acidification chamber through the anode membrane electrode, and react with the capture liquid saturated with carbon dioxide, the gas product is carbon dioxide, and the liquid product is the capture liquid after releasing CO2;

[0105] The reaction products of the acidification chamber flow into the acidification gas-liquid buffer tank, when the pressure in the acidification gas-liquid buffer tank is greater than or equal to 130 kPa, the gas control valve on the gas discharge pipeline is opened, CO2 is output and collected, when the pressure is less than the value, the gas control valve is closed and waits for the pressure to rise, and the capture liquid after releasing CO2 enters the cathode chamber for regeneration.

[0106] The gas product composition is detected every 20 minutes after the reaction starts, and the purity of CO2 gradually increases with the progress of the reaction, and the final product CO2 purity is greater than or equal to 98%.

[0107] Step 6.3 cathode chamber reaction (capture liquid regeneration)

[0108] The reduction reaction occurs in the cathode chamber to generate hydroxide and hydrogen, the hydrogen is transmitted to the anode chamber to be oxidized again, realizing the recycling of hydrogen; the hydroxide combines with the lean liquid and reacts to realize regeneration, obtaining regenerated capture liquid with capture ability;

[0109] H2 and the regenerated capture liquid flow into the cathode gas-liquid buffer tank together, when the pressure in the cathode gas-liquid buffer tank is greater than or equal to 130 kPa, the hydrogen is transported to the anode chamber under the action of pressure.

[0110] The reduction reaction formula is as follows:

[0111] 4H2O + 4e - → 4OH - + 2H2.

[0112] The electrolysis reaction parameters are as follows: the electrolysis reaction is carried out at room temperature; the current density is 100-2000 mA / cm2, and the cell voltage (electrolysis voltage) ranges from 0.3 to 30.0 V.

[0113] Preferably, the electrolysis voltage is about 5.0 V at a current density of 125 mA / cm2, and the hydraulic retention time is 2 min, at which value CO2 is released at nearly 100% and the energy consumption is low.

[0114] Further, the object of CO2 capture is carbon dioxide in the air, and the concentration of carbon dioxide in the air is about 420 ppm; the initial pH value of the CO2 capture liquid is 7-10, and the optimal pH is 10, which can simultaneously consider carbon dioxide capture and cooling tower operation, and the effect is best. The pH value of the CO2 capture liquid is dynamically adjusted according to the requirements of the cooling tower;

[0115] The temperature of the capture liquid is 23-43℃ (cooling tower circulating water working temperature interval).

[0116] Further, the CO2 capture liquid is a buffer type capture liquid, pH=10.00, which is specifically an absorbent solution formed by an absorbent and cooling tower circulating water; wherein the absorbent is a mixture of glycine, sodium hydroxide and sodium chloride; the concentration of the CO2 capture liquid is 1-3 mol / L; wherein the concentration of glycine is 0.25-3.00 mol / L; the concentration of sodium hydroxide is 0.15-1.50 mol / L; and the concentration of sodium chloride is 0.50 mol / L. In the case of initial pH=10.00, the proportions can be flexibly matched.

[0117] In the case of initial pH=10.00, the preferred absorbent solution proportion matching is as follows:

[0118] The concentration of glycine is 3.00 mol / L, the concentration of sodium hydroxide is 1.50 mol / L, the concentration of sodium chloride is 0.50 mol / L, and the initial pH is 10.00. At this time, after the CO2 capture liquid captures carbon dioxide in the air to saturation, the pH is about 9.35, and the capture amount of CO2 is 0.47 mol / L.

[0119] The CO2 capture liquid has low initial pH value under the premise of maintaining high CO2 load, can be applied to most scenes with strict pH limitation, meanwhile, the capture liquid is sodium glycine buffer solution, green and efficient, non-toxic, the CO2 capture liquid is buffer type capture liquid, which can maintain low pH and high CO2 load at the same time, is suitable for the pH requirement of the normal operation of the cooling tower system, and can directly use the circulating water cooling tower as an air contactor to capture CO2 in the air on the basis of guaranteeing the cooling function of the circulating water of the cooling tower.

[0120] The description of the application is given for the purpose of exemplification and description, and is not exhaustive or limiting to the application disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are chosen and described in order to best explain the principles of the application and its practical application, and to enable others skilled in the art to understand the application for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A device for directly capturing CO2 from the air using a cooling tower, characterized in that: Includes a CO2 capture module and an electrolytic CO2 release and capture liquid regeneration module; The CO2 capture module includes a circulating water cooling tower and a heat exchange system (7). The circulating water cooling tower is used to capture CO2 in the air, and the heat exchange system (7) is the circulating water system served by the circulating water cooling tower. The electrolytic CO2 release and capture liquid regeneration module includes a three-chamber electrolytic cell, an acidification chamber auxiliary component, a cathode chamber auxiliary component, an electrolyte input component, an external hydrogen inlet / outlet component, and a power supply device. The three-chamber electrolytic cell includes an anode chamber (12), an acidification chamber (14), and a cathode chamber (16). The inlet of the acidification chamber (14) is connected to an electrolyte input assembly, and the power supply is connected to the acidification chamber (14) and the cathode chamber (16). The acidification chamber auxiliary components include an acidification gas-liquid buffer tank (17), which is connected to the outlet of the acidification chamber (14) through a first gas-liquid mixing pipeline (31) and is connected to the inlet of the cathode chamber (16) through a liquid outlet pipeline (32). The cathode chamber accessory assembly includes a cathode gas-liquid buffer tank (21), which is connected to the outlet of the cathode chamber (16) via a second gas-liquid mixing pipeline (34); the cathode gas-liquid buffer tank (21) is connected to an inlet of the anode chamber (12) via a gas delivery pipeline (35); The external hydrogen inlet / outlet assembly includes an external hydrogen inlet pipe (39) and a hydrogen outlet pipe (38). The external hydrogen inlet pipe (39) is connected to the inlet of the anode chamber (12), and the hydrogen outlet pipe (38) is connected to the outlet of the anode chamber (12). The acidification chamber (14) is located between the cathode chamber (16) and the anode chamber (12). A cathode chamber membrane electrode (15) is provided between the acidification chamber (14) and the cathode chamber (16). The cathode chamber membrane electrode (15) functions to reduce water and generate hydrogen and hydroxide ions. An anode chamber membrane electrode (13) is provided between the acidification chamber (14) and the anode chamber (12). The anode chamber membrane electrode (13) functions to oxidize hydrogen and provide protons to the acidification chamber (14).

2. The device for directly capturing CO2 from the air using a cooling tower as described in claim 1, characterized in that: The circulating water cooling tower includes a cooling tower body (1), and inside the cooling tower body (1) from bottom to top are a water collection tank (2), a packing layer (3), a spray system (4) and a fan (5). The water collection tank (2) is located below the packing layer (3), and the spray system (4) is located above the packing layer (3). The fan (5) is located at the air outlet at the top of the tower body. The cooling tower body (1) is provided with a cooling tower air inlet, which is located between the spray system and the water collection pool; The heat exchange system (7) is connected to the spray system (4) and the water collection tank (2) through pipes; a centrifugal pump (6) is installed on the pipe between the heat exchange system (7) and the water collection tank (2).

3. The device for directly capturing CO2 from the air using a cooling tower as described in claim 1, characterized in that: The acidified gas-liquid buffer tank (17) is connected to a gas discharge pipeline (33) for transporting CO2. A gas control valve (19) is provided on the gas discharge pipeline (33) for regulating gas output. A first liquid control valve (20) is provided on the liquid discharge pipeline (32).

4. The device for directly capturing CO2 from the air using a cooling tower as described in claim 3, characterized in that: The acidification chamber auxiliary components also include a first pressure detector (18), which is a pressure sensor used to monitor the pressure in the acidification gas-liquid buffer tank and the connected acidification chamber. The first pressure detector (18) is located on the upper part of the acidification gas-liquid buffer tank (17). The first pressure detector (18) is connected to the gas control valve (19) in a circuit.

5. The device for directly capturing CO2 from the air using a cooling tower as described in claim 1, characterized in that: The cathode gas-liquid buffer tank (21) is connected to a regenerated liquid discharge pipeline (36), which is connected to a CO2 capture module. A second liquid control valve (24) is provided between the regenerated liquid discharge pipeline (36) and the CO2 capture module. A second pressure detector (22) is provided on the top of the cathode gas-liquid buffer tank (21).

6. The device for directly capturing CO2 from the air using a cooling tower as described in claim 1, characterized in that: The electrolyte input assembly includes an electrolyte input pipeline (37), which is connected to the inlet of the acidification chamber (14) and the CO2 capture module. The electrolyte input pipeline (37) is equipped with a flow meter (11), an inlet valve (10), a centrifugal pump (9) and a pH meter (8).

7. A method for directly capturing CO2 from the air using a cooling tower, characterized in that: The method is based on the apparatus for directly capturing CO2 in the air using a cooling tower as described in claim 2, and includes a CO2 capture method and an electrolytic desorption method for CO2 and a method for regenerating the capture liquid. CO2 capture methods include the following steps: Step 1: Turn on the centrifugal pump. After the CO2 collection liquid flows through the heat exchange system, it is sprayed by the spray system and flows from top to bottom through the packing layer under the action of gravity. At the same time, turn on the fan. Air enters the cooling tower body from the air inlet and flows from bottom to top through the packing layer. Step 2: The air stream and the CO2 capturing liquid stream come into full contact with the packing layer to capture CO2 in the air; after repeating this process for 12-48 hours, the absorbent aqueous solution will be basically saturated with CO2. Step 3: Continue the capture reaction process for 48 hours, and take 10 mL samples at 0, 2, 4, 6, 12, 24, 36, and 48 hours respectively. Use a pH meter and ion chromatograph to determine the pH and CO2 loading of the samples respectively. If either the CO2 loading or the pH value is satisfied, the absorbent aqueous solution can be judged to be saturated. The CO2 loading after saturation varies depending on the concentration of the absorbent aqueous solution. The electrolytic desorption of CO2 and regeneration of the collecting solution include the following steps: Step 4: Transfer the carbon dioxide-saturated collection solution to the three-chamber electrolytic cell. When the pH meter detects that pH ≤ 9.40, the carbon dioxide-saturated capture solution is sequentially transported and filled into the acidification chamber and the cathode chamber. After the two chambers are filled, the saturated absorbent aqueous solution flows into the acidification gas-liquid buffer tank and covers its outlet. Once the acidification chamber and cathode chamber are filled with liquid, the liquid supply is stopped. Step 5: Expel other gases from the anode chamber and cathode gas-liquid buffer tank, and fill with hydrogen. Step 6, Electrolysis reaction After the hydrogen is filled, close the valve between the cathode gas-liquid buffer tank and the CO2 capture module, stop the hydrogen supply, turn on the power, and the electrolysis reaction begins. After electrolysis for 1-3 minutes, the electrolyte input component resumes the electrolyte supply. Step 6.1, Anode Chamber Reaction An oxidation reaction occurs in the anode chamber, where H2 is oxidized to produce protons; The reaction formula is as follows: ； Step 6.2 Acidification chamber reaction Protons in the anode chamber enter the acidification chamber through the anode membrane electrode and react with the carbon dioxide-saturated trapping solution. The gaseous product is carbon dioxide, and the liquid product is the trapping solution after the release of CO2. The reaction products in the acidification chamber flow into the acidification gas-liquid buffer tank. When the pressure in the acidification gas-liquid buffer tank is ≥130kPa, CO2 is output and collected. When the pressure is less than this value, CO2 output is stopped and the pressure is allowed to rise. The collected liquid after releasing CO2 enters the cathode chamber for regeneration. The composition of the gaseous products was measured every 20 minutes after the reaction started. As the reaction proceeded, the purity of CO2 gradually increased, and the purity of the final product CO2 was ≥98%. Step 6.3 Cathode Chamber Reaction A reduction reaction occurs in the cathode chamber to generate hydroxide ions and hydrogen gas. The hydrogen gas is then transported to the anode chamber to be oxidized again, thus achieving the recycling of hydrogen gas. The hydroxide ions combine with the lean solution and react to achieve regeneration, resulting in a regenerated collection solution with collection capabilities. H2 and the regenerated collection liquid flow into the cathode gas-liquid buffer tank through the pipeline. When the pressure in the cathode gas-liquid buffer tank is ≥130kPa, hydrogen is transported to the anode chamber under pressure. The reduction reaction equation is as follows: 。 8. The method for directly capturing CO2 from the air using a cooling tower as described in claim 7, characterized in that: The CO2 capture solution is a buffered capture solution with a pH of 10.

00. It is formed by an absorbent and cooling tower circulating water, wherein the absorbent is a mixture of glycine, sodium hydroxide, and sodium chloride. The concentration of the CO2 capture solution is 1-3 mol / L; wherein the concentration of glycine is 0.25-3.00 mol / L; the concentration of sodium hydroxide is 0.15-1.50 mol / L; and the concentration of sodium chloride is 0.50 mol / L.

9. The method for directly capturing CO2 from the air using a cooling tower as described in claim 8, characterized in that: The specific ratio of the absorbent solution in the CO2 capturing solution, with an initial pH of 10.00, is as follows: The concentration of glycine was 3.00 mol / L, the concentration of sodium hydroxide was 1.50 mol / L, the concentration of sodium chloride was 0.50 mol / L, and the initial pH was 10.

00. After the CO2 capturing solution captured carbon dioxide from the air to saturation, the pH was ≈9.35, and the CO2 capturing capacity was 0.47 mol / L.

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