Direct air carbon capture system coupled with closed cooling tower fan

Abstract

A direct air carbon capture system coupled with a closed cooling tower fan comprises a direct air carbon capture device coupled with the closed cooling tower fan through a heat exchanger; a fan of the closed cooling tower is communicated with a gas path of the heat exchanger and is used for conveying wet and hot air in the closed cooling tower to the heat exchanger; the heat exchanger is used for cooling and dehumidifying wet and hot air, and the treated adsorption gas is conveyed to the direct air carbon capture device; the direct air carbon capture device comprises at least one group of adsorption-desorption towers and is used for carrying out direct carbon capture and thermal desorption on the adsorbed gas to obtain high-concentration CO2 gas. And other air conveying devices do not need to be additionally arranged to provide power, so that the energy consumption is reduced, the traditional treatment flow is optimized, the complexity of the system is reduced, and the cost is greatly reduced. The heat exchanger is adopted to treat wet and hot air, collected heat energy is used for providing energy for the CO2 thermal desorption process, waste heat utilization is achieved, and the energy utilization rate is increased.

Description

Technical Field

[0001] The present application relates to the field of CO2 capture technology, and in particular to a direct air carbon capture system coupled with a closed cooling tower fan. Background Art

[0002] Direct Air Capture is a new carbon reduction technology that captures carbon dioxide directly from the atmosphere through adsorption or absorbents. The captured high-concentration CO2 can be permanently sealed deep underground and can also be used to manufacture various chemical products. It has great potential and broad application prospects. Overseas, companies such as Climeworks, Carbon Engineering and Global Thermostat have achieved large-scale application of direct air carbon capture technology, with production capacity ranging from 1 ton to 4,000 tons per year; China is still in the pilot stage, and as carbon reduction technology urgently needs to develop rapidly, this technology and equipment still has the problem of high energy consumption caused by fans and desorption processes during use, which seriously weakens the intensity of carbon reduction.

[0003] Chinese patent CN116989535A discloses a heat pump driven direct air carbon capture system based on exhaust gas evaporative cooling, which consists of three parts: an evaporative cooling subsystem, a heat pump subsystem and a DAC subsystem. The equipment connection is complex, the stability is poor, the overall system maintenance is difficult, and the desorption and regeneration process consumes a lot of energy, especially when using high-temperature CO2 for purging.

[0004] CN117018805A mentions an energy-saving direct air carbon capture system coupled with compressed air energy storage. The system requires an additional air compression energy release subsystem, which increases the complexity and maintenance difficulty of the system. In addition, the system is restricted by air compression energy storage technology and is not very mature.

[0005] CN118274590A discloses a hydrogen production and direct air carbon capture system coupled with compressed air energy storage. The system has an additional compressed air energy storage subsystem. Although it improves energy utilization efficiency, the overall complexity of the system is significantly increased and the commercial prospects are unclear. Summary of the invention

[0006] In order to solve at least one of the above technical problems, a direct air carbon capture system coupled with a closed cooling tower fan is provided.

[0007] In a first aspect, an embodiment of the present application provides a direct air carbon capture system coupled to a closed cooling tower fan, comprising: a direct air carbon capture device and a heat exchanger, wherein the direct air carbon capture device is coupled to the closed cooling tower fan through the heat exchanger;

[0008] The fan of the closed cooling tower is connected to the air path of the heat exchanger, and is used to transport the hot and humid air in the closed cooling tower to the heat exchanger; the heat exchanger is used to cool and dehumidify the hot and humid air, and the adsorbed gas after treatment is transported to the direct air carbon capture device;

[0009] The direct air carbon capture device includes at least one set of adsorption-desorption towers, which are used to perform direct carbon capture and thermal desorption on the adsorbed gas to obtain high-concentration CO2 gas.

[0010] In combination with the first aspect of the present application, in an optional embodiment, the direct air carbon capture system also includes: at least two CO2 gas sensors and an automatic control device; one of the at least two CO2 gas sensors is used to collect the CO2 concentration signal in the air emitted by the at least one group of adsorption-desorption towers, and the other is used to collect the CO2 concentration signal of the high-concentration CO2 gas released by the at least one group of adsorption-desorption towers, and feed the concentration signal back to the automatic control device; the automatic control device performs closed-loop control on the fan of the closed cooling tower according to the CO2 concentration signal to improve the carbon capture efficiency.

[0011] In combination with the first aspect of the present application, in an optional embodiment, it also includes a water tank, which is connected to the heat exchanger through a water circulation pipeline and connected to the closed cooling tower through a water supply pipeline. The water tank is used to collect condensed water generated by dehumidification treatment from the heat exchanger and replenish it to the closed cooling tower.

[0012] In conjunction with the first aspect of the present application, in an optional embodiment, the heat exchanger includes a heat transfer medium for collecting heat energy of the hot and humid air;

[0013] The adsorption tower and the desorption tower of the at least one set of adsorption-desorption towers each include an adsorption bed, in which an adsorbent and a heat exchange pipeline are arranged; the heat exchange pipeline is connected to the heat exchanger through the heat transfer medium main pipeline;

[0014] The heat transfer medium enters the desorption tower in the at least one group of adsorption-desorption towers through the heat transfer medium main pipeline and the heat exchange pipeline to provide heat for the thermal desorption of CO2.

[0015] In combination with the first aspect of the present application, in an optional embodiment, the at least one group of adsorption-desorption towers is connected to the heat exchanger through a heat transfer medium reflux pipeline and a heat transfer medium reflux main pipeline, and the heat transfer medium flows out of the at least one group of adsorption-desorption towers and then flows back to the heat exchanger through the heat transfer medium reflux pipeline and the heat transfer medium reflux main pipeline.

[0016] In combination with the first aspect of the present application, in an optional embodiment, the at least one group of adsorption-desorption towers includes a first tower and a second tower, and the carbon dioxide adsorption process of the first tower and the second tower is carried out alternately, and / or the thermal desorption process of the first tower and the second tower is carried out alternately.

[0017] In combination with the first aspect of the present application, in an optional embodiment, the first tower is gas-circuit coupled with the heat exchanger through a first adsorption gas pipeline and an adsorption gas inlet pipeline, and the second tower is gas-circuit coupled with the heat exchanger through a second adsorption gas pipeline and the adsorption gas inlet pipeline, and the first adsorption gas pipeline and the second adsorption gas pipeline are respectively provided with a first adsorption gas valve and a second adsorption gas valve.

[0018] In combination with the first aspect of the present application, in an optional embodiment, the first tower is connected to the heat exchanger through a first heat exchange pipeline and a heat transfer medium main pipeline; the second tower is connected to the heat exchanger through a second heat exchange pipeline and the heat transfer medium main pipeline; and a first heat transfer medium valve and a second heat transfer medium valve are respectively provided on the first heat exchange pipeline and the second heat exchange pipeline.

[0019] In combination with the first aspect of the present application, in an optional embodiment, the first tower is connected to the heat exchanger through a first heat transfer medium return pipeline and the heat transfer medium main pipeline; the second tower is connected to the heat exchanger through a second heat transfer medium return pipeline and the heat transfer medium main pipeline; the first heat transfer medium return pipeline and the second heat transfer medium return pipeline are respectively provided with a first heat transfer medium return pipe valve and a second heat transfer medium return pipe valve.

[0020] In combination with the first aspect of the present application, in an optional embodiment, the direct air carbon capture device also includes a first vacuum pump, the first tower is connected to the first vacuum pump through a first high-concentration CO2 pipeline and a high-concentration CO2 main pipeline, and the second tower is connected to the first vacuum pump through a second high-concentration CO2 pipeline and a high-concentration CO2 main pipeline; the first high-concentration CO2 pipeline and the second high-concentration CO2 pipeline are respectively provided with a first high-concentration CO2 valve and a second high-concentration CO2 valve.

[0021] The direct air carbon capture system provided in the embodiment of the present application is cleverly designed for carbon capture of waste gas from steel mills. The direct air carbon capture device is coupled with a closed cooling tower that is essential in the steel production process. The fan of the closed cooling tower is used as a power source to transport the hot and humid air in the closed cooling tower to the direct air carbon capture device for carbon capture, thereby avoiding the system fan, wind power generation component or air energy storage system used in the prior art. There is no need to add other air delivery devices to provide power, which reduces energy consumption, optimizes the traditional processing flow, reduces the complexity of the system, and greatly reduces costs. The fan of the closed cooling tower is modified and an automatic control device is added to accurately adjust the air volume and wind speed of the fan according to the concentration of CO2, thereby improving the CO2 capture efficiency. At the same time, it does not affect the normal operation of the closed cooling tower, thus ensuring the stability of the operation of the entire system. By using a heat exchanger to treat the hot and humid air, the heat energy and moisture in the hot and humid air obtained after circulating cooling in a closed cooling tower are collected and recycled. On the one hand, the heat energy is used to provide energy for the CO2 thermal desorption process, realizing waste heat utilization and improving energy utilization; on the other hand, the water content in the captured air is reduced, thereby improving the CO2 adsorption efficiency, optimizing resource allocation, greatly reducing the energy consumption of the direct air carbon capture system, and improving energy efficiency.

[0022] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of a direct air carbon capture system according to an embodiment;

[0024] Figure 2 A schematic diagram of a direct air carbon capture system according to another embodiment. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] The present application embodiment provides a direct air carbon capture system 100 coupled to a closed cooling tower fan, referring to Figure 1 , comprising: a direct air carbon capture device 101 and a heat exchanger 5. The direct air carbon capture device 101 is coupled to a closed cooling tower fan 2 through the heat exchanger 5.

[0027] The closed cooling tower 1 adopts a closed cooling tower that is essential in the steel production process. It includes a fan 2, which is connected to the heat exchanger 5 gas path, and is used to transport the hot and humid air in the closed cooling tower 1 to the heat exchanger 5. The heat exchanger 5 is used to cool and dehumidify the hot and humid air to obtain adsorbed gas. The treated adsorbed gas is transported to the direct air carbon capture device. The heat exchanger 5 contains a heat transfer medium, which is used to exchange heat with the hot and humid air, cool it, and recover heat. The drop in the temperature of the hot and humid air causes the water vapor to condense to form liquid water, thereby achieving dehumidification and recovering the moisture therein.

[0028] The direct air carbon capture device includes at least one group of adsorption-desorption towers 9, 10, which are used to directly capture carbon from the adsorbed gas to obtain high-concentration CO2 gas. The adsorption tower and desorption tower of at least one group of adsorption-desorption towers both include adsorption beds 21, 22, and the adsorption beds are filled with adsorbents. Optionally, the adsorbent includes a solid physical adsorbent, such as activated carbon, molecular sieves, MOFs, etc. The adsorption tower can achieve direct carbon capture and thermal desorption of CO2 in the air. The principle of direct carbon capture is that the solid physical adsorbent utilizes the van der Waals force interaction between CO2 molecules and the adsorbent surface to adsorb CO2 onto the surface of the solid physical adsorbent, thereby achieving the separation of CO2 from other gases. The principle of thermal desorption is that the increase in temperature can enable the CO2 molecules adsorbed on the solid surface to obtain more energy, thereby detaching from the surface of the solid physical adsorbent.

[0029] The direct air carbon capture device also includes a first vacuum pump 11 connected to at least one set of adsorption-desorption towers 9, 10, for extracting the high-concentration CO2 after desorption.

[0030] The embodiment of the present application is cleverly designed for carbon capture of exhaust gas from steel mills. The direct air carbon capture device is coupled with a closed cooling tower that is essential in the steel production process. The fan 2 of the closed cooling tower is used as a power source to transport the hot and humid air in the closed cooling tower to the direct air carbon capture device for carbon capture. This avoids the system fan, wind power generation components or air energy storage system used in the prior art, and there is no need to add other air conveying devices to provide power, thereby reducing energy consumption, optimizing the traditional processing flow, reducing the complexity of the system, and greatly reducing costs.

[0031] The heat exchanger 5 is used to cool and dehumidify the hot and humid air discharged from the closed cooling tower 1, thereby improving the CO2 capture efficiency.

[0032] In a possible implementation of the present application, the direct air carbon capture system also includes: at least two CO2 gas sensors 13 and an automatic control device 3. One of the at least two CO2 gas sensors is used to collect the CO2 concentration signal in the air discharged from at least one group of adsorption-desorption towers, and the other is used to collect the CO2 concentration signal of the high-concentration CO2 gas released by the at least one group of adsorption-desorption towers, and feed the above concentration signal back to the automatic control device 3. The automatic control device 3 performs closed-loop control on the fan 2 of the closed cooling tower 1 according to the CO2 concentration signal to improve the carbon capture efficiency. Each tower includes an exhaust pipeline and a high-concentration CO2 pipeline, which are respectively used to discharge air after CO2 adsorption and high-concentration CO2 released by thermal desorption. At least two CO2 gas sensors are arranged at the end of the first vacuum pump 13 and the end of the exhaust pipeline, and are respectively used to collect CO2 concentration signals in the exhaust air and high-concentration CO2 gas.

[0033] The automatic control device 3 adjusts the air volume and wind speed of the fan according to the collected CO2 concentration signal to control the contact time between the hot and humid air and the heat exchanger 5, thereby controlling the temperature and humidity of the adsorbed gas within an appropriate range, thereby improving the carbon capture efficiency, that is, the ability to adsorb CO2. Optionally, the automatic control device 3 automatically adjusts the air volume and wind speed of the fan after comparing the collected CO2 concentration with the optimal value range.

[0034] In the above embodiment, the closed cooling tower fan 2 is modified and an automatic control device 3 is added to adjust the air volume, wind speed and other conditions of the fan according to the CO2 concentration. The CO2 capture efficiency is improved as much as possible without affecting the normal operation of the closed cooling tower, thereby ensuring the stability of the operation of the entire system.

[0035] In a possible implementation of the present application, the direct air carbon capture system also includes a water tank 6, which is connected to the heat exchanger 5 through a water circulation pipeline 45 and is connected to the closed cooling tower 1 through a water supply pipeline 27. The water tank 6 is used to collect condensed water generated by the dehumidification treatment from the heat exchanger 5 and replenish it to the closed cooling tower 1.

[0036] The heat exchanger 5 includes a heat transfer medium for collecting heat energy of hot and humid air. The adsorption tower 9 and the desorption tower 10 of at least one set of adsorption-desorption towers each include an adsorption bed 21, 22, in which an adsorbent and at least one heat exchange pipeline 28, 29 are arranged; at least one heat exchange pipeline is connected to the heat exchanger 5 through a heat transfer medium main pipeline 30. The heat transfer medium enters the desorption tower in at least one set of adsorption-desorption towers through the heat transfer medium main pipeline 30 and at least one heat exchange pipeline to provide heat for the thermal desorption of CO2.

[0037] At least one set of adsorption-desorption towers 9, 10 is connected to the heat exchanger 5 through at least one heat transfer medium return pipeline 31, 32 and a heat transfer medium return main pipeline 33. After the heat transfer medium flows out of at least one set of adsorption-desorption towers, it flows back to the heat exchanger 5 through at least one heat transfer medium return pipeline 31, 32 and a heat transfer medium return main pipeline 33. In this way, the recycling of the heat transfer medium is achieved.

[0038] By using a heat exchanger 5 to process the hot and humid air, the heat energy and moisture in the hot and humid air obtained after circulating cooling in a closed cooling tower are collected and recycled. On the one hand, the heat energy is used to provide energy for the CO2 thermal desorption process, thereby realizing the utilization of waste heat and improving the energy utilization rate; on the other hand, the water content in the captured air is reduced, thereby improving the CO2 adsorption efficiency, optimizing resource allocation, greatly reducing the energy consumption of the direct air carbon capture system, and improving energy efficiency.

[0039] In addition, the coupling of the direct air carbon capture system with the closed cooling tower fan in the steel production process is a carbon emission reduction technology for steel mills. This application can achieve energy conservation, emission reduction, cost reduction and efficiency improvement in the steel industry, and has broad market demand and application prospects.

[0040] refer to Figure 2 In a possible embodiment of the present application, at least one group of adsorption-desorption towers includes a first tower 9 and a second tower 10, and the carbon dioxide adsorption process of the first tower 9 and the second tower 10 is performed alternately, and / or the thermal desorption process of the first tower and the second tower is performed alternately. That is, when the first tower 9 is in the CO2 adsorption stage, the second tower 10 is in the thermal desorption regeneration stage, and when the first tower 9 is in the thermal desorption regeneration stage, the second tower 10 is in the CO2 adsorption stage. In this way, the working efficiency of the direct air carbon capture system is improved.

[0041] The first tower 9 includes a first adsorption bed 21 and a first heat exchange pipeline 28. The second tower 10 includes a second adsorption bed 22 and a second heat exchange pipeline 29. The first tower 9 is gas-circuit coupled with the heat exchanger through the first adsorption gas pipeline and the adsorption gas inlet pipeline, and the second tower 10 is gas-circuit coupled with the heat exchanger 5 through the second adsorption gas pipeline 41 and the adsorption gas inlet pipeline 39. The first adsorption gas pipeline 40 and the second adsorption gas pipeline 41 are respectively provided with a first adsorption gas valve 55 and a second adsorption gas valve 56.

[0042] The first tower 9 is connected to the heat exchanger 5 through the first heat exchange pipeline 28 and the heat transfer medium main pipeline 30. The second tower 10 is connected to the heat exchanger 5 through the second heat exchange pipeline 29 and the heat transfer medium main pipeline 30. The first heat exchange pipeline 28 and the second heat exchange pipeline 29 are respectively provided with a first heat transfer medium valve 57 and a second heat transfer medium valve 58. The first tower 9 is connected to the heat exchanger 5 through the first heat transfer medium return pipeline 31 and the heat transfer medium main pipeline 30. The second tower 10 is connected to the heat exchanger 5 through the second heat transfer medium return pipeline 32 and the heat transfer medium main pipeline 30. A second vacuum pump 7 is provided on the heat transfer medium main pipeline 30 for providing power for the circulation of the heat transfer medium. The first heat transfer medium return pipeline 31 and the second heat transfer medium return pipeline 32 are respectively provided with a first heat transfer medium return pipe valve 53 and a second heat transfer medium return pipe valve 54.

[0043] The heat exchanger 5 is connected to the humid hot air outlet pipeline 62 through the humid hot air inlet pipeline 38, and is used to receive the humid hot air discharged by the fan 2. The heat exchanger 5 is connected to the adsorption gas pipeline 40 of the first tower 9 and the adsorption gas pipeline 41 of the second tower 10 through the adsorption gas inlet pipeline 39, respectively, and is used to transmit the adsorption gas formed by the treatment of the humid hot air to the first tower 9 or the second tower 10. The heat exchanger 5 contains a heat transfer medium inside, and a heat exchanger insulation layer 19 is arranged outside the heat exchanger 5. The heat transfer medium pipeline insulation layer 20 is arranged outside the heat transfer medium main pipeline 30, the first heat exchange pipeline 28 and the second heat exchange pipeline 29. The heat transfer medium flows out of the heat exchanger 5, passes through the first heat exchange pipeline 28 or the second heat exchange pipeline 29, and then flows back to the heat exchanger 5 through the first heat transfer medium return pipeline 31 or the second heat transfer medium return pipeline 32, thereby realizing the recycling of the heat transfer medium. The heat exchanger 5 outputs the condensed water formed after the dehumidification process to the water tank 6 through the water return pipe 45, so as to realize the recycling of the condensed water.

[0044] The direct air carbon capture device 101 further includes a first vacuum pump 11, and the first tower is connected to the first vacuum pump 11 through a first high-concentration CO2 pipeline 42 and a high-concentration CO2 main pipeline 44. The second tower 10 is connected to the first vacuum pump 11 through a second high-concentration CO2 pipeline 43 and a high-concentration CO2 main pipeline 44. The first high-concentration CO2 pipeline 42 and the second high-concentration CO2 pipeline 43 are respectively provided with a first high-concentration CO2 valve 59 and a second high-concentration CO2 valve 60.

[0045] A first carbon dioxide gas sensor 13 is provided at the end of the first vacuum pump 11, which is used to collect the high-concentration CO2 concentration signal discharged from the first tower 9 and the second tower 10, and to provide CO2 concentration signal feedback. The first tower 9 and the second tower 10 also include a first exhaust pipeline 63 and a second exhaust pipeline 64, which are used to discharge the air after carbon capture treatment. The first exhaust pipeline 63 and the second exhaust pipeline 64 are connected to the exhaust main pipeline 65. A second carbon dioxide gas sensor 8 is provided at the end of the exhaust main pipeline 65, which is used to collect the CO2 concentration in the air discharged from the first exhaust pipeline 63 and the second exhaust pipeline 64, and to provide CO2 concentration signal feedback. 46 and 47 respectively represent the CO2 concentration feedback signals obtained by the first carbon dioxide gas sensor 13 and the second carbon dioxide gas sensor 8. 12 represents high-concentration CO2 gas. By using two carbon dioxide gas sensors to monitor the concentration of the product - high-concentration CO2 gas, and the concentration of CO2 in the exhaust pipeline, the accuracy of CO2 concentration measurement is improved, the control accuracy of the fan is improved, and the carbon capture efficiency is further improved.

[0046] Figure 2 The detailed structure of the closed cooling tower 1 is shown, including: a fan 2, a dehydrator 14, a spray head 15, a spray water pipeline 24, a water circulation pipeline 23, a spray water tank 16, an overflow pipeline 25, a water supply pipeline 27, a dry cold air inlet 34, an air inlet 18, a hot water inlet 35, a cold water outlet 36, a spray water 61, a liquid pump 4, a drain pipe valve 48, an overflow pipe valve 49, a drain pipe 26, a water supply pipe valve 50, a water supply port 17, a cold water outlet 36, a humid hot air outlet pipeline 62, an exhaust pipe 37, and an exhaust pipe valve 51.

[0047] The dehydration plate 14 recovers the spray water to the spray water tank 16. After the hot and humid air passes through the heat exchanger 5, the heat and water are recovered. The heat recovery principle is heat exchange, which is used in the thermal desorption process; the water recovery principle is that the temperature drops and the water vapor condenses to form liquid water. The condensed water is stored in the water tank 6 and supplied to the spray water tank 16 through the water supply pipe 27 and the water supply port 17. The hot water enters the water circulation pipe 23 through the hot water inlet 34, flows out from the cold water outlet 36 after being cooled by the spray water 61, and continues to be used in the steel production process.

[0048] The working process of the direct air carbon capture system of the embodiment of the present application is as follows:

[0049] When the closed cooling tower 1 is working, the fan 2 drives the dry cold air from the outside to enter the closed cooling tower 1 from the dry cold air inlet 34, and interacts with the spray water 61 sprayed from the spray head 15. The spray water 61 is accelerated to evaporate and dissipate heat, and the heat and humidity of the dry cold air are increased. The formed humid hot air is sent out by the fan 2 through the dehydration plate 14. The exhausted humid hot air reaches the heat exchanger 5 through the humid hot air outlet pipeline 62 and the humid hot air inlet pipeline 38. The humid hot air inlet pipeline 38 is provided with a humid hot air inlet pipeline valve 52.

[0050] The carbon capture process and the desorption regeneration process are described by taking the first tower 9 in the adsorption stage and the second tower 10 in the thermal desorption stage as an example. First, the first adsorbed gas valve 55, the second heat transfer medium valve 58, the second high-concentration CO2 valve 60 and the second heat transfer medium return pipe valve 54 are placed in an open state, and the second adsorbed gas valve 56, the first heat transfer medium valve 57, the first high-concentration CO2 valve 59 and the first heat transfer medium return pipe valve 53 are closed. The adsorbed gas is sent to the first tower for CO2 capture, and the captured air is discharged through the first exhaust pipe 63. At the same time, the heat transfer medium enters the second tower 10 through the second heat exchange pipe 29 to provide the necessary heat for CO2 desorption. The heat transfer medium is finally recovered to the heat exchanger 5 through the second heat transfer medium return pipe 32 for recycling. After the CO2 desorption is completed, it is extracted by the vacuum pump 11 to obtain high-concentration CO2.

[0051] The first carbon dioxide gas sensor 13 disposed at the end of the first vacuum pump 11 and the second carbon dioxide gas sensor 8 disposed at the end of the exhaust main pipeline 65 monitor the concentration of the high-concentration CO2 product and provide a front-end feedback signal to the automatic control device 3. The automatic control device 3 adjusts the air volume and wind speed of the fan according to the concentration signal of the collected high-concentration CO2 gas to control the contact time between the humid hot air and the heat exchanger 5, thereby controlling the temperature and humidity of the adsorbed gas, and further improving the CO2 capture efficiency as much as possible without affecting the normal operation of the closed cooling tower 1, so that the concentration of the adsorbed CO2 product reaches the desired state, and the stability of the CO2 capture efficiency is achieved.

[0052] The first tower 9 and the second tower 10 are used alternately, that is, when the second tower 10 is in the adsorption stage, the first tower 9 is in the thermal desorption stage. At this time, the first adsorption gas valve 55, the second heat transfer medium valve 58, the second high concentration CO2 valve 60 and the second heat transfer medium return pipe valve 54 are closed, and the second adsorption gas valve 56, the first heat transfer medium valve 57, the first high concentration CO2 valve 59 and the first heat transfer medium return pipe valve 53 are opened. In this way, the carbon capture efficiency of the system is improved.

[0053] When the solid physical adsorbent and the heat transfer medium are replaced regularly, the moist hot air inlet pipe valve 52 is closed and the exhaust pipe valve 51 is opened to cut off the coupling between the heat exchanger 5 and the closed cooling tower to avoid interference with the closed cooling tower and the steel production process.

[0054] Optionally, the automatic control device 3 uses a PLC controller. The carbon dioxide gas sensor 13 uses an infrared carbon dioxide gas sensor. Solid physical adsorbents include but are not limited to activated carbon, molecular sieves, MOFs, and the like.

[0055] The embodiment of the present application recycles the heat energy of the humid hot air for the thermal desorption of CO2 and the regeneration of the adsorbent, and recycles the moisture of the humid hot air for the replenishment of the spray water tank 16 of the closed cooling tower, thereby improving the resource utilization rate. The present application couples the fan of the closed cooling tower, which is essential in the steel production process, and the fan of the closed cooling tower delivers air to the capture module to provide power support. There is no need to add other air delivery devices, which simplifies the system and reduces costs. It can replace the fan of the original DAC system, realize the simplification of the system, and reduce the cost and complexity of system equipment. The embodiment of the present application solves the problems of the prior art that the desorption and regeneration process requires additional power and heat, and recycles and utilizes the energy in the humid hot air output by the fan, provides heat for the desorption and regeneration process, and realizes heat transfer through heat exchange. During the heat transfer process, the temperature is reduced and the water vapor in the air condenses to form liquid water to realize water reflux replenishment, optimize resource allocation, improve resource utilization, and reduce system energy consumption and increase economic value.

[0056] The existing technology has not yet developed a low-cost, low-energy, and high-efficiency direct air carbon capture technology specifically for steel companies. This method is coupled with the fan of the closed cooling tower, which is essential in the steel production process. It is a CCUS technology for energy conservation, emission reduction, cost reduction, and efficiency improvement for steel plants, and has strong market targeting. The high-concentration CO2 obtained can be used later, with good economic benefits. In addition, the annual carbon emissions of steel companies account for as much as 16% nationwide, and its market demand and application prospects are broad.

[0057] The carbon capture capacity of the system can be calculated using the following formula:

[0058] Carbon capture amount = carbon capture efficiency ╳ atmospheric carbon dioxide concentration ╳ system processing capacity ╳ time

[0059] The CO2 concentration in the air of a steel plant is set to 0.5%, and the air volume of the closed cooling tower fan is 50,000-100,000 m 3 / h, where the carbon capture efficiency is determined by the type and performance of the adsorbent and is affected by operating conditions such as temperature, pressure and humidity. Here, 90% is taken for estimation. According to the above formula, the system can capture about 3850-7700 tons of CO2 per year.

[0060] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A direct air carbon capture system coupled to a closed cooling tower fan, characterized in that: include: a direct air carbon capture device and a heat exchanger, the direct air carbon capture device being coupled to a closed cooling tower fan via the heat exchanger; The fan of the closed cooling tower is in gas communication with the heat exchanger, and is used to transport the hot and humid air in the closed cooling tower to the heat exchanger; The heat exchanger is used to cool and dehumidify the hot and humid air, and the treated adsorbed gas is transported to the direct air carbon capture device; The direct air carbon capture device includes at least one set of adsorption-desorption towers for directly capturing carbon from the adsorbed gas and performing thermal desorption to obtain high-concentration CO2 gas.

2. The direct air carbon capture system according to claim 1, characterized in that Also includes: At least two CO2 gas sensors and an automatic control device; one of the at least two CO2 gas sensors is used to collect the CO2 concentration signal in the air discharged from the at least one group of adsorption-desorption towers, and the other is used to collect the CO2 concentration signal of the high-concentration CO2 gas released by the at least one group of adsorption-desorption towers, and feed the concentration signal back to the automatic control device; the automatic control device performs closed-loop control on the fan of the closed cooling tower according to the CO2 concentration signal to improve the carbon capture efficiency.

3. The direct air carbon capture system according to claim 1 or 2, characterized in that: It also includes a water tank, which is connected to the heat exchanger through a water circulation pipeline and connected to the closed cooling tower through a water supply pipeline. The water tank is used to collect condensed water generated by dehumidification treatment from the heat exchanger and replenish it to the closed cooling tower.

4. The direct air carbon capture system according to claim 1 or 2, characterized in that: The heat exchanger includes a heat transfer medium for collecting heat energy of the hot and humid air; The adsorption tower and the desorption tower of the at least one set of adsorption-desorption towers both include an adsorption bed, in which an adsorbent and a heat exchange pipeline are arranged; The heat exchange pipeline is connected to the heat exchanger through the heat transfer medium main pipeline; The heat transfer medium enters the desorption tower in the at least one group of adsorption-desorption towers through the heat transfer medium main pipeline and the heat exchange pipeline to provide heat for the thermal desorption of CO2.

5. The direct air carbon capture system according to claim 4, characterized in that: The at least one group of adsorption-desorption towers is connected to the heat exchanger through a heat transfer medium reflux pipeline and a heat transfer medium reflux main pipeline. After the heat transfer medium flows out of the at least one group of adsorption-desorption towers, it flows back to the heat exchanger through the heat transfer medium reflux pipeline and the heat transfer medium reflux main pipeline.

6. The direct air carbon capture system according to claim 1, characterized in that The at least one group of adsorption-desorption towers comprises a first tower and a second tower, and the carbon dioxide adsorption process of the first tower and the second tower are performed alternately, and / or the thermal desorption process of the first tower and the second tower are performed alternately.

7. The direct air carbon capture system according to claim 6, characterized in that The first tower is gas-circuit coupled with the heat exchanger through a first adsorption gas pipeline and an adsorption gas inlet pipeline, and the second tower is gas-circuit coupled with the heat exchanger through a second adsorption gas pipeline and the adsorption gas inlet pipeline. The first adsorption gas pipeline and the second adsorption gas pipeline are respectively provided with a first adsorption gas valve and a second adsorption gas valve.

8. The direct air carbon capture system according to claim 6, characterized in that The first tower is connected to the heat exchanger through a first heat exchange pipeline and a heat transfer medium main pipeline; the second tower is connected to the heat exchanger through a second heat exchange pipeline and the heat transfer medium main pipeline; a first heat transfer medium valve and a second heat transfer medium valve are respectively provided on the first heat exchange pipeline and the second heat exchange pipeline.

9. The direct air carbon capture system according to claim 8, characterized in that The first tower is connected to the heat exchanger through a first heat transfer medium return pipeline and the heat transfer medium main pipeline; the second tower is connected to the heat exchanger through a second heat transfer medium return pipeline and the heat transfer medium main pipeline; the first heat transfer medium return pipeline and the second heat transfer medium return pipeline are respectively provided with a first heat transfer medium return pipe valve and a second heat transfer medium return pipe valve.

10. The direct air carbon capture system according to claim 6, characterized in that The direct air carbon capture device also includes a first vacuum pump, the first tower is connected to the first vacuum pump through a first high-concentration CO2 pipeline and a high-concentration CO2 main pipeline, and the second tower is connected to the first vacuum pump through a second high-concentration CO2 pipeline and a high-concentration CO2 main pipeline; the first high-concentration CO2 pipeline and the second high-concentration CO2 pipeline are respectively provided with a first high-concentration CO2 valve and a second high-concentration CO2 valve.

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