Air pollutant purification system and purification method

Abstract

The application provides an air pollutant purification system and purification method, relates to the field of air pollutant purification, and comprises a refrigeration assembly, an air circulation assembly, a desorption assembly and a discharge assembly. The liquid nitrogen refrigeration technology can be used to treat various gaseous pollutants, which is difficult to achieve by a single technology. The gaseous pollutants are frozen or liquefied by low temperature, and the efficient removal of various pollutants can be achieved in a short time. In addition, the air pollutant purification system comprises three working conditions of purification, desorption and discharge, the three working conditions are closely matched, a closed loop system is formed, and efficient purification of various air pollutants is achieved. The closed loop system ensures complete removal of pollutants and efficient operation of the system, and has high energy utilization efficiency and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of air pollutant purification, and more particularly to an air pollutant purification system and purification method. Background Technology

[0002] In indoor work and living areas, the widespread presence of paints, coatings, adhesives, rubber, and mechanical equipment, along with natural emissions from human respiration, results in a large amount of gaseous pollutants in the air, such as carbon dioxide, benzene compounds, hydrocarbons, formaldehyde, sulfur dioxide, and hydrogen sulfide. These air pollutants affect human health and necessitate air purification. In general situations, ventilation can be used for air purification. However, when the concentration of external air pollutants is high, or when the heat or humidity load is excessive, or in situations such as underground spaces where ventilation is difficult, the industry often employs a combination of multiple air purification technologies, such as adsorption with porous materials of different pore sizes, alkaline absorption, metal oxide catalysis, and photocatalysis.

[0003] The above solutions have the problem that a single technology can only handle a limited number of pollutants. To achieve the goal of purifying multiple air pollutants simultaneously, it is necessary to combine multiple technologies. Summary of the Invention

[0004] In view of this, the present invention proposes an air pollutant purification system and purification method to solve the problem that a single technology can only handle a limited number of pollutant types.

[0005] The technical solution of this invention is implemented as follows:

[0006] On one hand, the present invention provides an air pollutant purification system, comprising:

[0007] A refrigeration assembly includes a liquid nitrogen container and a freezing chamber. A heat exchange coil is installed in the freezing chamber. The liquid nitrogen container is connected to the inlet end of the heat exchange coil, and the outlet end of the heat exchange coil is connected to an exhaust assembly for discharging used nitrogen gas to the outside of the system through the exhaust assembly.

[0008] An air circulation assembly includes a blower, a return air duct network, a supply air duct network, and a regenerator. The return air duct network is connected to the air inlet of the freezing chamber through the regenerator, and is used to allow the air to be purified to enter the freezing chamber after passing through the regenerator for freezing or liquefying gaseous pollutants. The air outlet of the freezing chamber is connected to the supply air duct network through the regenerator. The blower is connected in series with the supply air duct network, and the supply air duct network is used to send the purified air back to the control area.

[0009] Desorption components are used to remove solid contaminants from the low-temperature surfaces of the regenerator and freezing chamber;

[0010] Emission components are used to discharge desorbed gaseous pollutants to the outside of the system.

[0011] Based on the above technical solution, preferably, the regenerator is provided with an air inlet channel and a first heat exchange channel, the return air duct network includes a return air duct, a return air inlet and a second electric shut-off valve, the inlet end of the return air duct is located in the return air zone and is connected to multiple return air inlets, the outlet end of the return air duct is connected to the inlet of the air inlet channel, the outlet of the air inlet channel is connected to the air inlet of the freezing chamber, and the second electric shut-off valve is provided on the return air duct;

[0012] The air supply network includes an air supply duct, a first electric shut-off valve, a flow meter, and air outlets. The inlet end of the air supply duct is connected to the outlet of the first heat exchange channel, and the inlet of the first heat exchange channel is connected to the air outlet of the freezing chamber. The outlet end of the air supply duct is located in the air supply area and is connected to multiple air outlets. The blower, the first electric shut-off valve, and the flow meter are sequentially arranged on the air supply duct along the air flow direction.

[0013] Based on the above technical solution, preferably, the exhaust assembly includes an exhaust pipe, an exhaust heater, a third electric shut-off valve and a fourth electric shut-off valve. One end of the exhaust pipe is connected to the outlet end of the heat exchange coil, and the other end is used to connect to the external environment of the system. The exhaust heater, the third electric shut-off valve and the fourth electric shut-off valve are all arranged sequentially on the exhaust pipe along the air flow direction of the exhaust pipe.

[0014] Based on the above technical solution, preferably, it also includes a precooling pipeline, which includes a first pipeline, a second pipeline, and a fifth electric shut-off valve. The regenerator is also provided with a second heat exchange channel. One end of the first pipeline is connected to the outlet end of the heat exchange coil, and the other end is connected to the inlet of the second heat exchange channel. The fifth electric shut-off valve is provided on the first pipeline. One end of the second pipeline is connected to the outlet of the second heat exchange channel, and the other end is connected to the exhaust pipeline between the third and fourth electric shut-off valves.

[0015] Based on the above technical solution, preferably, the desorption assembly includes a desorption heater, a desorption cross-pipe and a sixth electric shut-off valve, the two ends of the desorption cross-pipe are respectively connected to the return air pipeline and the supply air pipeline, and the desorption heater and the sixth electric shut-off valve are both installed on the desorption cross-pipe.

[0016] The emission assembly includes a purge pipeline, a nitrogen container, a seventh electric shut-off valve, a third pipeline, and an eighth electric shut-off valve. The nitrogen container is connected to the air supply pipeline between the blower and the regenerator via the purge pipeline. The seventh electric shut-off valve is installed on the purge pipeline. One end of the third pipeline is connected to the freezing chamber, and the other end is connected to the exhaust pipeline between the third and fourth electric shut-off valves. The eighth electric shut-off valve is installed on the third pipeline.

[0017] Based on the above technical solution, preferably, the liquid nitrogen container is connected to the inlet of the heat exchange coil via a vacuum insulated pipeline. An electric regulating valve is also installed on the vacuum insulated pipeline. A first temperature sensor is installed at the inlet of the return air pipeline, a second temperature sensor is installed at the air inlet of the freezing chamber, a third temperature sensor is installed at the air outlet of the freezing chamber, a fourth temperature sensor is installed inside the freezing chamber, a fifth temperature sensor is installed at the outlet of the heat exchange coil, and a sixth temperature sensor is installed at the inlet of the supply air pipeline. An incoming air pressure sensor and at least one incoming air pollutant concentration sensor are installed at the end of the return air pipeline near the regenerator. A return air pressure sensor and at least one reverse air pollutant concentration sensor are installed at the end of the supply air pipeline near the regenerator. A nitrogen concentration sensor is also installed on the third pipeline.

[0018] Secondly, the present invention also discloses an air pollutant purification method, which utilizes the air pollutant purification system described in the first aspect, comprising the following steps:

[0019] S1, Cooling stage: Low-temperature nitrogen gas from the liquid nitrogen container is introduced into the heat exchange coil of the freezing chamber to provide a low-temperature cold source for the entire purification system;

[0020] S2. Pre-cooling stage: After the blower starts, the air to be purified in the environment is drawn into the return air duct network and enters the system, is delivered to the regenerator, and then enters the freezing chamber to exchange heat with the heat exchange coil for cooling. The low-temperature air leaves the freezing chamber and enters the regenerator, which can cool the regenerator body and the incoming air. At the same time, the temperature of the return air itself rises, leaves the regenerator, enters the air supply duct network and is delivered to the air outlet, and returns to the environment. When the air temperature in the freezing chamber, the temperature of the regenerator body, the temperature of the return air and the temperature of the incoming air all drop to the rated operating point, the air purification stage begins.

[0021] S3, Air purification stage: Incoming air enters the freezing chamber and exchanges heat with the heat exchange coil to cool down. Gaseous pollutants in the air are liquefied and frozen on the surface of the heat exchange coil and in the freezing chamber, and the air is purified.

[0022] S4. After the air purification stage has reached a certain time, the heater and freezing chamber are heated by the desorption component to desorb the pollutants.

[0023] S5. After the pollutant desorption is completed, the desorbed air pollutants in the system are replaced by the emission components, and steps S1 to S4 are repeated.

[0024] Based on the above technical solution, preferably, when the inlet temperature of the freezing chamber is greater than 112K, the fourth electric shut-off valve is opened, and a portion of the low-temperature pre-cooled nitrogen is diverted through the fourth electric shut-off valve to the first pipeline and enters the regenerator to accelerate the cooling process of the regenerator; when the inlet temperature of the freezing chamber is less than or equal to 112K, the supply of low-temperature nitrogen to the regenerator by the pre-cooling pipeline is stopped through the fourth electric shut-off valve.

[0025] Based on the above technical solution, preferably, when the detected value of the incoming air pollutant concentration sensor is less than the set target value, the operating frequency of the blower is 10% of the rated air volume of the blower; when the detected value of the incoming air pollutant concentration sensor is less than 20% of the set target value, the operating frequency of the blower increases exponentially; when the detected value of the incoming air pollutant concentration sensor is greater than 20% of the set target value, the operating frequency of the blower increases linearly. When the detected value of the fifth temperature sensor is less than or equal to 97K, the opening degree of the electric regulating valve is 10% of the rated opening degree; when the detected value of the fifth temperature sensor is greater than 97K, the opening degree of the electric regulating valve increases linearly or exponentially.

[0026] Based on the above technical solution, preferably, when the pressure difference between the incoming and outgoing air increases to twice the initial value, or the CO2 concentration difference between the incoming and outgoing air decreases to less than 30%, it is determined that pollutant desorption is required; when the detection values ​​of the second, third, fourth, and sixth temperature sensors are all greater than the ambient temperature value, it is determined that pollutant desorption is complete, and the blower and desorption heater are turned off; when the nitrogen concentration detected by the nitrogen concentration sensor is greater than 99%, it is determined that pollutant emission is complete.

[0027] The present invention has the following advantages over the prior art:

[0028] (1) The air pollutant purification system disclosed in this invention utilizes liquid nitrogen freezing technology to treat various gaseous pollutants (such as CO2, benzene compounds, hydrocarbons, formaldehyde, etc.), which is difficult to achieve with a single technology. By freezing or liquefying gaseous pollutants at low temperatures, it can achieve efficient removal of multiple pollutants in a short time. Furthermore, this air pollutant purification system includes three operating modes: purification, desorption, and emission. These three modes work closely together to form a closed-loop system, achieving efficient purification of multiple air pollutants. The closed-loop system ensures complete removal of pollutants and efficient system operation, exhibiting extremely high energy utilization efficiency and environmental friendliness. This closed-loop system is particularly suitable for places with severe external pollution or limited ventilation, providing a comprehensive and effective solution for improving indoor air quality.

[0029] (2) The dual-channel design of the regenerator (air inlet channel and first heat exchange channel) can make full use of the heat exchange process of the gas, realize the pre-cooling of the unpurified air and the heat energy recovery of the purified air, greatly improve the energy-saving effect of the system and reduce the refrigeration burden of the freezing chamber.

[0030] (3) By installing an exhaust heater on the exhaust pipe, the low-temperature nitrogen discharged from the heat exchange coil can be heated in time to increase the temperature of nitrogen discharge, thereby avoiding condensation and icing at the discharge port due to temperature difference during the discharge process.

[0031] (4) By pre-cooling the return gas, the air entering the freezer chamber has already had its temperature lowered. This reduces the cooling load required by the freezer components, helps improve the freezing efficiency of air pollutants, and further enhances the system's purification effect. The pre-cooled airflow exchanges heat with low-temperature nitrogen as it passes through the regenerator, enabling the air to reach a lower temperature before entering the freezer chamber. This helps to freeze or liquefy gaseous pollutants more effectively, improves purification efficiency, and reduces the cooling load on the freezer components.

[0032] (5) The desorption and emission components provide an effective solution to the problem of pollutant condensation in low-temperature environments. The desorption component heats the air inside the closed pipeline system, converting condensed pollutants into a gaseous state through circulating heated air, thus preventing pollutants from freezing and accumulating in the freezing chamber and regenerator, which would affect purification efficiency. The emission component ensures that the desorbed gaseous pollutants can be safely discharged from the system, preventing secondary pollution. The overall design improves the long-term stability and energy efficiency of the system, reduces maintenance costs, and provides higher operational reliability and efficiency for air pollutant purification systems.

[0033] (6) By adding temperature, pressure, and concentration sensors and vacuum-insulated piping, the system's ability to monitor and regulate parameters such as temperature, pressure, and pollutant concentration in real time has been improved. The installation of these sensors enables the system to control the operation more precisely during cooling, desorption, and emission, avoiding unnecessary waste of cold source and improving the safety of pollutant emission and the stability of system operation.

[0034] (7) By adjusting the operating frequency of the blower based on pollutant concentration, the system can save energy when air pollution is low and respond quickly when pollutant concentration increases, ensuring purification effect. Furthermore, through precise control of liquid nitrogen flow rate by the fifth temperature sensor, the system can avoid energy waste while ensuring cooling effect, achieving a dynamic balance between energy saving and efficiency. Flexible adjustment of the blower frequency and the opening of the electric regulating valve enables the system to respond quickly to environmental changes and maintain the stability of the air purification and cooling process. This multi-variable collaborative control not only improves the system's automation level but also enhances its operational stability under different loads. (8) Through comprehensive monitoring of airflow pressure difference, CO2 concentration difference, and multi-point temperature sensor data, intelligent control of the pollutant desorption process is achieved. When the system detects conditions requiring desorption, it automatically starts the desorption process; after desorption and pollutant emission are completed, the system automatically shuts down related equipment to save energy. Through this multi-parameter, multi-condition joint control, the system can efficiently and safely complete pollutant desorption and emission, improving the overall operational stability and reliability. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the overall structure of the air pollutant purification system disclosed in this invention.

[0037] Figure 2 This is a schematic diagram of the air pollutant purification process disclosed in this invention;

[0038] Figure 3 This is a schematic diagram of the air pollutant desorption process disclosed in this invention;

[0039] Figure 4 This is a schematic diagram of the air pollutant emission process disclosed in this invention;

[0040] Figure label:

[0041] 1. Refrigeration assembly; 11. Liquid nitrogen container; 111. Vacuum insulated piping; 112. Electric regulating valve; 12. Freezing chamber; 13. Heat exchange coil; 14. Exhaust assembly; 141. Exhaust piping; 142. Exhaust heater; 143. Third electric shut-off valve; 144. Fourth electric shut-off valve;

[0042] 2. Air circulation assembly; 21. Supply fan; 22. Return air duct network; 221. Return air duct; 222. Return air outlet; 223. Second electric shut-off valve; 224. Return air outlet;

[0043] 23. Air supply duct network; 231. Air supply pipeline; 232. First electric shut-off valve; 233. Flow meter; 234. Air outlet; 24. Regenerator; 241. Air inlet channel; 242. First heat exchange channel; 243. Second heat exchange channel;

[0044] 3. Desorption assembly; 31. Desorption heater; 32. Desorption cross-pipe; 33. Sixth electric shut-off valve; 4. Discharge assembly; 41. Purge line; 42. Nitrogen container; 43. Seventh electric shut-off valve; 44. Third line; 45. Eighth electric shut-off valve; 5. Precooling line; 51. First line; 52. Second line; 53. Fifth electric shut-off valve;

[0045] T1, First temperature sensor; T2, Second temperature sensor; T3, Third temperature sensor; T4, Fourth temperature sensor; T5, Fifth temperature sensor; T6, Sixth temperature sensor; P1, Incoming air pressure sensor; P2, Return air pressure sensor; X1, Incoming air pollutant concentration sensor; X2, Pollutant concentration sensor; X3, Nitrogen concentration sensor. Detailed Implementation

[0046] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0047] like Figure 1 As shown, combined with Figure 2-4 This invention discloses an air pollutant purification system, including a refrigeration component 1, an air circulation component 2, a desorption component 3, and an emission component 4.

[0048] The refrigeration component 1 includes a liquid nitrogen container 11 and a freezing chamber 12. A heat exchange coil 13 is installed in the freezing chamber 12. The liquid nitrogen container 11 is connected to the inlet end of the heat exchange coil 13, and the outlet end of the heat exchange coil 13 is connected to the exhaust component 14 for discharging used nitrogen to the outside of the system through the exhaust component 14.

[0049] The liquid nitrogen container 11 provides a cryogenic cold source for the entire purification system. The liquid nitrogen in the container 11 is at a temperature of 77K (-196℃). The liquid nitrogen container 11 exists in a gas-liquid two-phase state, with liquid nitrogen at the bottom and nitrogen gas at the top. After absorbing heat, the liquid nitrogen continuously evaporates into nitrogen gas, providing a continuous supply of cryogenic nitrogen gas. The cryogenic nitrogen gas generated by the liquid nitrogen container is transported to the freezing chamber 12, maintaining the cryogenic state of the freezing chamber 12 to achieve the cryogenic liquefaction or freezing of air pollutants.

[0050] The medium inside the heat exchange coil 13 is low-temperature nitrogen gas supplied by the liquid nitrogen container 11, which can reduce the temperature of the space outside the heat exchange coil 13 (i.e. the main space of the freezing chamber 12) to close to -196°C. At this temperature, the pollutant components in the air entering the freezing chamber 12 are frozen or liquefied.

[0051] The exhaust assembly 14 is used to exhaust the used nitrogen to the outside of the system after heat exchange is completed in the freezing chamber 12.

[0052] The air circulation assembly 2 includes a blower 21, a return air duct 22, a supply air duct 23, and a regenerator 24. The return air duct 22 is connected to the air inlet of the freezing chamber 12 through the regenerator 24, and is used to allow the air to be purified to enter the freezing chamber 12 after passing through the regenerator 24 for freezing or liquefying gaseous pollutants. The air outlet of the freezing chamber 12 is connected to the supply air duct 23 through the regenerator 24. The blower 21 is connected in series with the supply air duct 23, and the supply air duct 23 is used to send the purified air back to the control area.

[0053] In this embodiment, the return air duct 22 draws in polluted air from the room and sends it into the system for purification. The regenerator 24 reduces energy loss during air circulation. Specifically, the regenerator 24 can pre-cool the return air and preheat the supply air, improving energy utilization. The supply fan 21 ensures airflow, guaranteeing that the purified air can return to the control area in a timely manner. The supply air duct 23 sends the purified air back to the work or living area, forming a closed-loop air circulation. Through the closed-loop air circulation system, the secondary entry of polluted air from outside the system is avoided, ensuring stable purification effect. The regenerator 24 improves energy efficiency, making the system operation more energy-efficient.

[0054] The desorption component is used to remove solid contaminants from the low-temperature surfaces of the regenerator 24 and the freezing chamber 12. In a low-temperature environment, contaminants will solidify on the heat exchange surface and need to be desorbed over time. The desorption component 3 ensures that these contaminants can be removed regularly to avoid excessive accumulation of contaminants in the system and affect heat exchange efficiency.

[0055] Emission component 4 is used to discharge desorbed gaseous pollutants to the outside of the system. The desorbed gaseous pollutants need to be safely discharged to prevent them from circulating within the system. Emission component 4 ensures that pollutants do not re-enter the room, avoiding secondary accumulation of pollutants within the system and ensuring stable system operation. The discharged gas can be further treated, such as through adsorption towers or catalytic reactions, to reduce environmental pollution.

[0056] The air pollutant purification system disclosed in this invention utilizes liquid nitrogen freezing technology to treat various gaseous pollutants (such as CO2, benzene compounds, hydrocarbons, formaldehyde, etc.), which is difficult to achieve with a single technology. By freezing or liquefying gaseous pollutants at low temperatures, it can achieve efficient removal of multiple pollutants in a short time. Furthermore, this air pollutant purification system includes three operating modes: purification, desorption, and emission. The sequential connection of these three modes forms a complete closed-loop system, achieving efficient purification of multiple air pollutants. The closed-loop system ensures complete removal of pollutants and efficient system operation, exhibiting extremely high energy utilization efficiency and environmental friendliness. This closed-loop system is particularly suitable for locations with severe external pollution or limited ventilation, providing a comprehensive and effective solution for improving indoor air quality.

[0057] In this embodiment, the regenerator 24 is provided with an air inlet channel 241 and a first heat exchange channel 242. The two ends of the air inlet channel 241 are connected to the inlet of the return air duct 221 and the air inlet of the freezing chamber 12, respectively, so that the air entering from the return air duct 221 enters the freezing chamber 12 through the air inlet channel 241. The first heat exchange channel 242 is connected to the air outlet of the freezing chamber 12 and the inlet of the air supply duct 231, so that the discharged cooling air undergoes heat exchange and enters the air supply duct network 23 after heat exchange.

[0058] The direct connection between the air intake channel 241 and the freezing chamber 12 ensures that the return air undergoes heat exchange before entering the freezing chamber 12, pre-cooling the return air and reducing the consumption of liquid nitrogen. The function of the first heat exchange channel 242 is to recover the cold energy of the low-temperature air discharged from the freezing chamber 12 to pre-cool the return air in the air intake channel 241, thereby reducing the energy demand of the freezing process and achieving significant overall energy-saving effect of the system.

[0059] The dual-channel design of the regenerator 24 (air inlet channel 241 and first heat exchange channel 242) can make full use of the heat exchange process of the gas to achieve pre-cooling of unpurified air and heat recovery of purified air, which greatly improves the energy-saving effect of the system and reduces the refrigeration burden of the freezing chamber 12.

[0060] The return air duct network 22 includes a return air duct 221, return air inlets 224, and a second electrically operated shut-off valve 223. The inlet end of the return air duct 221 is located in the return air zone and is connected to multiple return air inlets 224 for drawing in air from various parts of the room. The outlet end of the return air duct 221 is connected to the inlet of the air intake channel 241, and the outlet of the air intake channel 241 is connected to the air inlet of the freezing chamber 12. The second electrically operated shut-off valve 223 is installed on the return air duct 221.

[0061] In this embodiment, the return air duct 221 is used to collect air from the environment to be purified, and multiple return air inlets 224 ensure that air is drawn in from different areas, avoiding uneven air purification in certain areas. The second electric shut-off valve 223 is used to control whether air from the environment is drawn into the return air duct 221. When in air purification mode, the second electric shut-off valve 223 needs to be open; when in desorption mode and emission mode, the second electric shut-off valve 223 needs to be closed.

[0062] The air supply network 23 includes an air supply duct 231, a first electric shut-off valve 232, a flow meter 233, and air outlets 234. The inlet end of the air supply duct 231 is connected to the outlet of the first heat exchange channel 242, and the inlet of the first heat exchange channel 242 is connected to the air outlet of the freezing chamber 12. The outlet end of the air supply duct 231 is located in the air supply area and is connected to multiple air outlets 234. The design of multiple air outlets 234 allows the purified air to be evenly distributed throughout the indoor space. The blower 21, the first electric shut-off valve 232, and the flow meter 233 are sequentially arranged on the air supply duct 231 along the air flow direction. The first electric shut-off valve 232 is used to control the air flow in the air supply duct 231, and the flow meter 233 is used to monitor the air supply volume in real time.

[0063] In this implementation, the first electric shut-off valve 232 needs to be opened when the entire system is in purification mode, and closed when in desorption mode and discharge mode.

[0064] Based on the above technical solution, when low-temperature nitrogen is introduced into the heat exchange coil 13 and heats and freezes or liquefies the air pollutants introduced into the refrigeration chamber, the temperature of the low-temperature nitrogen will rise. At this time, this part of the nitrogen needs to be discharged in time to ensure that the liquid nitrogen container 11 can continuously introduce low-temperature nitrogen into the heat exchange coil 13. Since the temperature of the low-temperature nitrogen is low, the temperature will still be relatively low after heat exchange. If it is discharged directly at this time, it may cause icing or condensation at the discharge port, affecting the discharge of low-temperature nitrogen and affecting the safety of the system.

[0065] Therefore, this embodiment shows a preferred structural configuration of the exhaust assembly 14. Specifically, the exhaust assembly 14 includes an exhaust pipe 141, an exhaust heater 142, a third electric shut-off valve 143, and a fourth electric shut-off valve 144. One end of the exhaust pipe is connected to the outlet end of the heat exchange coil 13, and the other end is used to connect to the external environment of the system. The exhaust heater 142, the third electric shut-off valve 143, and the third electric shut-off valve 144 are all sequentially arranged on the exhaust pipe 141 along the air flow direction of the exhaust pipe 141.

[0066] In this embodiment, the exhaust heater 142 can heat the low-temperature nitrogen gas discharged from the heat exchange coil 13 in a timely manner, thereby increasing the temperature of the nitrogen gas discharge and avoiding condensation and icing at the discharge port due to temperature difference during the discharge process.

[0067] In this embodiment, the third electric shut-off valve 143 primarily controls the opening and closing of the exhaust pipe 141, while the fourth electric shut-off valve 144 controls the overall exhaust flow. During purification, both the third and fourth electric shut-off valves are open. During desorption and emission, the third electric shut-off valve 143 is closed, and the fourth electric shut-off valve 144 is open. Thus, during desorption and emission, the third electric shut-off valve 143 is closed, preventing the low-temperature nitrogen in the heat exchange coil 13 from being discharged through the emission assembly 4. However, during emission, the desorbed gaseous pollutants in the freezing chamber 12 can be introduced into the exhaust pipe 141, and with the fourth electric shut-off valve 144 open, the desorbed gaseous pollutants are discharged outside the system. These pollutants will not return to the system and can be treated by other gas treatment equipment, preventing environmental pollution.

[0068] As some preferred embodiments, a precooling line 5 is also included, which includes a first line 51, a second line 52 and a fifth electric shut-off valve 53.

[0069] In addition to the original air inlet channel 241 and the first heat exchange channel 242, the regenerator 24 also has a second heat exchange channel 243 for heat exchange with the low-temperature nitrogen in the pre-cooling pipeline 5. This design allows the regenerator 24 to handle two airflows of different temperatures simultaneously, achieving more efficient energy exchange.

[0070] One end of the first pipeline 51 is connected to the outlet end of the heat exchange coil 13, and the other end is connected to the inlet of the second heat exchange channel 243, which is responsible for introducing the low-temperature nitrogen gas discharged from the heat exchange coil 13 into the regenerator 24.

[0071] The fifth electric shut-off valve 53 is installed on the first pipeline 51 to control the timing and flow rate of cryogenic nitrogen flowing into the regenerator 24, ensuring the controllability of the cryogenic nitrogen recovery process.

[0072] One end of the second pipe 52 is connected to the outlet of the second heat exchange channel 243, and the other end is connected to the exhaust pipe 141 between the third electric shut-off valve 143 and the fourth electric shut-off valve 144. It is used to guide the low-temperature nitrogen gas passing through the regenerator 24 to the exhaust pipe 141 to realize the discharge of low-temperature nitrogen gas.

[0073] By pre-cooling the return gas, the air entering the freezer chamber has already had its temperature lowered. This reduces the cooling load required by the refrigeration unit 1, helps improve the freezing efficiency of air pollutants, and further enhances the system's purification effect. The pre-cooled airflow exchanges heat with low-temperature nitrogen gas as it passes through the regenerator 24, enabling the air to reach an even lower temperature before entering the freezer chamber. This helps to freeze or liquefy gaseous pollutants more effectively, improving purification efficiency and reducing the cooling load on the refrigeration unit 1.

[0074] The system consumes a large amount of energy to generate low-temperature nitrogen during the freezing process. The cooling capacity of this low-temperature nitrogen is recovered through the pre-cooling pipeline 5, avoiding energy waste caused by direct discharge. By using the low-temperature nitrogen discharged from the freezer to pre-cool the air to be purified in the return flow, the cooling energy consumption required in the regenerator 24 can be reduced, thereby improving the overall energy utilization efficiency of the system.

[0075] Because the low-temperature nitrogen gas undergoes heat exchange in the regenerator 24, the exhaust gas is preheated by the return air in the regenerator 24 before being emitted. This not only increases the exhaust temperature and reduces the impact on the external environment, but also prevents condensation or icing during the emission process.

[0076] This embodiment shows a preferred structural configuration of the desorption assembly 3. Specifically, the desorption assembly 3 includes a desorption heater 31, a desorption cross-pipe 32, and a sixth electric shut-off valve 33. The two ends of the desorption cross-pipe 32 are connected to the return air duct 221 and the supply air duct 231, respectively. The desorption heater 31 and the sixth electric shut-off valve 33 are both mounted on the desorption cross-pipe 32.

[0077] In this embodiment, the desorption crosspipe 32 connects the return air duct 221 and the supply air duct 231, thus forming a closed pipeline system consisting of the desorption crosspipe 32, the return air duct 221, the freezing chamber 12, the supply air duct 231, and the blower 21. Opening the sixth electric shut-off valve 33 can open this closed pipeline system, establishing an internal circulation.

[0078] It is worth noting that when desorption is required, the first electric shut-off valve 232 and the second electric shut-off valve 223 need to be closed. In this way, the closed pipeline system will not be connected to the indoor environment, nor will it introduce the air to be purified.

[0079] The desorption heater 31 heats the air inside the closed piping system, while the blower 21 circulates the heated air within the system. This heated air then heats the contaminants condensed inside the freezing chamber 12 and the regenerator 24, causing them to transform into a gaseous state, thus achieving desorption. This process effectively prevents the long-term accumulation of contaminants, ensuring that they can be periodically removed and preventing any impact on system performance.

[0080] After the contaminants solidified inside the freezing chamber 12 and the regenerator 24 have been desorbed, it is necessary to discharge the gaseous contaminants in a timely manner in order to implement a new round of purification. In order to achieve the discharge of gaseous contaminants, this embodiment shows a preferred structural configuration of the discharge component 4.

[0081] Specifically, the emission assembly 4 includes a purge pipe 41, a nitrogen container 42, a seventh electric shut-off valve 43, a third pipe 44, and an eighth electric shut-off valve 45. The nitrogen container 42 is connected to the air supply pipe 231 located between the blower 21 and the regenerator 24 via the purge pipe 41. The seventh electric shut-off valve 43 is installed on the purge pipe 41. One end of the third pipe 44 is connected to the freezing chamber 12, and the other end is connected to the exhaust pipe 141 between the third electric shut-off valve 143 and the fourth electric shut-off valve 144. The eighth electric shut-off valve 45 is installed on the third pipe 44.

[0082] Using the above technical solution, under this working condition, the blower 21 is in the off state. At this time, both the seventh electric shut-off valve 43 and the eighth electric shut-off valve 45 are open, and nitrogen is continuously introduced into the air supply pipeline 231 through the nitrogen container 42. After the nitrogen mixes with the gaseous pollutants in the closed pipeline system, it is discharged into the external environment through the third pipeline 44 and the exhaust pipeline 141. This can be connected to other gas purification equipment for further treatment of gaseous pollutants.

[0083] The desorption assembly 3 and the emission assembly 4 provide an effective solution to the problem of pollutant condensation in low-temperature environments. The desorption assembly 3 heats the air inside the closed piping system, converting condensed pollutants into a gaseous state through circulating heated air, thus preventing pollutants from freezing and accumulating in the freezing chamber 12 and regenerator 24, which would affect purification efficiency. The emission assembly 4 ensures that the desorbed gaseous pollutants can be safely discharged from the system, preventing secondary pollution. The overall design improves the long-term stability and energy efficiency of the system, reduces maintenance costs, and provides higher operational reliability and efficiency for air pollutant purification systems.

[0084] In this embodiment, the liquid nitrogen container 11 is connected to the inlet of the heat exchange coil 13 via a vacuum-insulated pipeline 111, and an electric regulating valve 112 is also installed on the vacuum-insulated pipeline 111. The cryogenic nitrogen gas generated by the liquid nitrogen tank is transported to the freezing chamber 12 through the vacuum-insulated pipeline 111 (the pipeline wall has a vacuum insulation layer, which can reduce the loss of cold energy of the cryogenic nitrogen gas), maintaining the cryogenic state of the freezing chamber 12 to achieve cryogenic liquefaction or freezing of air pollutants. The electric regulating valve 112 is used to regulate the flow rate of cryogenic nitrogen gas from the liquid nitrogen container 11 into the freezing chamber 12.

[0085] A first temperature sensor T1 is installed at the inlet of the return air duct 221 to monitor the temperature of the incoming air to the regenerator 24. A second temperature sensor T2 is installed at the inlet of the freezing chamber 12 to monitor the inlet air temperature, and a third temperature sensor T3 is installed at the outlet of the freezing chamber 12 to monitor the outlet air temperature. A fourth temperature sensor T4 is installed inside the freezing chamber 12 to monitor the internal air temperature. A fifth temperature sensor T5 is installed at the outlet of the heat exchange coil 13 to monitor the temperature at which the low-temperature nitrogen leaves the freezing chamber 12. A sixth temperature sensor T6 is installed at the inlet of the supply air duct 231 to monitor the temperature of the return air to the regenerator 24.

[0086] The return air duct 221, near the regenerator 24, is equipped with an incoming air pressure sensor P1 and at least one incoming air pollutant concentration sensor X1. The supply air duct 231, near the regenerator 24, is equipped with a return air pressure sensor P2 and at least one reverse air pollutant concentration sensor X2. The incoming air pressure sensor P1 monitors the incoming air pressure to the regenerator 24, and the return air pressure sensor P2 monitors the return air pressure to the regenerator 24. The incoming air pollutant concentration sensor X1 monitors the concentration of a specific gaseous pollutant in the incoming air to the regenerator 24 (before purification), and the reverse air pollutant concentration sensor X2 monitors the concentration of a specific gaseous pollutant in the return air to the regenerator 24 (after purification).

[0087] A nitrogen concentration sensor is also installed on the third pipeline 44 to monitor the nitrogen concentration emitted under emission conditions.

[0088] By adding temperature, pressure, and concentration sensors, as well as vacuum-insulated piping 111, the system's ability to monitor and regulate parameters such as temperature, pressure, and pollutant concentration in real time has been improved. The inclusion of these sensors allows for more precise control of the system during cooling, desorption, and emission processes, avoiding unnecessary waste of cold energy and enhancing the safety of pollutant emissions and the stability of system operation.

[0089] This invention discloses a method for purifying air pollutants, comprising the following steps:

[0090] S1, Cooling stage: Low-temperature nitrogen gas in liquid nitrogen container 11 is introduced into heat exchange coil 13 of freezing chamber 12 to provide a low-temperature cold source for the entire purification system;

[0091] S2, Pre-cooling stage: After the blower 21 is started, the air to be purified in the environment is drawn into the return air duct network 22 and enters the system, is delivered to the regenerator 24, and then enters the freezing chamber 12 to exchange heat with the heat exchange coil 13 for cooling. The low temperature air leaves the freezing chamber 12 and enters the regenerator 24, which can cool the regenerator 24 body and the incoming air. At the same time, the temperature of the return air itself rises, leaves the regenerator 24, enters the air supply duct network 23 and is delivered to the air outlet 234, and returns to the environment. When the air temperature in the freezing chamber 12, the temperature of the regenerator body, the temperature of the return air and the temperature of the incoming air all drop to the rated operating point, the air purification stage begins.

[0092] S3, Air purification stage: Incoming air enters the freezing chamber 12 and exchanges heat with the heat exchange coil 13 to cool down. Gaseous pollutants in the air are liquefied and frozen on the surface of the heat exchange coil 13 and inside the freezing chamber 12, and the air is purified.

[0093] S4. After the air purification stage has reached a certain time, the heater and freezing chamber 12 are heated by the desorption component 3 to desorb the pollutants.

[0094] S5. After the pollutant desorption is completed, the desorbed air pollutants in the system are replaced by the emission component 4, and steps S1 to S4 are repeated.

[0095] In some specific embodiments, when the inlet temperature of the freezing chamber 12 is greater than 112K, the fourth electric shut-off valve 144 is opened, and a portion of the low-temperature pre-cooled nitrogen gas is diverted through the fourth electric shut-off valve 144 to the first pipeline 51 and enters the regenerator 24 to accelerate the cooling process of the regenerator 24; when the inlet temperature of the freezing chamber 12 is less than or equal to 112K, the supply of low-temperature nitrogen gas from the pre-cooling pipeline 5 to the regenerator 24 is stopped with respect to the fourth electric shut-off valve 144.

[0096] When the inlet air temperature of the freezing chamber 12 exceeds 112K, it means that the air temperature entering the freezing chamber 12 is relatively high. At this time, the system opens the fourth electric shut-off valve 144, allowing some low-temperature nitrogen to enter the first pipeline 51 through the fourth electric shut-off valve 144 and flow to the regenerator 24. After the low-temperature pre-cooled nitrogen enters the regenerator 24, the temperature of the return air can be quickly reduced through heat exchange. Through the pre-cooling of the return gas, the air entering the freezing chamber has been pre-cooled. This reduces the cooling load required by the refrigeration component 1, helps to improve the freezing efficiency of air pollutants, and further improves the purification effect of the system. The pre-cooled airflow exchanges heat with the low-temperature nitrogen when passing through the regenerator 24, which enables the air to reach a lower temperature before entering the freezing chamber, which helps to freeze or liquefy gaseous pollutants more effectively, improves purification efficiency, and reduces the cooling load of the refrigeration component 1.

[0097] When the inlet air temperature of the freezing chamber 12 drops to 112K or lower, it means that the system temperature has reached a relatively ideal cooling state, and no additional pre-cooling nitrogen is needed to cool the regenerator 24. The system will then close the fourth electric shut-off valve 144, stopping the supply of low-temperature nitrogen to the regenerator 24. This automated control mechanism not only improves the system's operating efficiency but also avoids unnecessary energy consumption, enhancing the overall energy-saving effect of the system.

[0098] In this embodiment, the fourth electric shut-off valve 144 provides the system with automated temperature regulation capabilities, allowing for flexible adjustment of the pre-cooled nitrogen flow rate based on the actual inlet temperature of the freezing chamber 12. This not only helps maintain system temperature stability but also effectively improves the operating efficiency of the purification system.

[0099] When the value detected by the incoming air pollutant concentration sensor X1 is less than the set target value, the operating frequency of the blower 21 is 10% of the rated air volume of the blower 21. This means that when the air pollutant concentration is low, the system only needs to operate with a very low air volume. Because there are fewer pollutants, the load on the purification system is lighter, which helps to save energy.

[0100] When the pollutant concentration sensor X1 detects a value less than 20% of the set target value, the operating frequency of the blower 21 increases exponentially. At this point, the system recognizes that the pollutant concentration is in a low range, and the frequency of the blower 21 increases exponentially to gradually increase airflow and meet the needs of treating light pollution. This exponential growth mode allows the system to maintain low energy consumption in the initial stage while rapidly increasing airflow capacity as pollutant concentration increases.

[0101] When the incoming air pollutant concentration sensor X1 detects a value greater than 20% of the set target value, the operating frequency of the blower 21 increases linearly. At this point, the air pollutant concentration exceeds a certain range of the preset target value, meaning the air purification load increases. The system needs to linearly increase the frequency of the blower 21 to ensure a larger airflow to handle higher concentrations of pollutants. This linear increase adjustment method offers greater controllability and is suitable for maintaining system stability under higher loads.

[0102] When the detected value of the fifth temperature sensor T5 is less than or equal to 97K, the opening degree of the electric regulating valve 112 is 10% of the rated opening degree. The fifth temperature sensor T5 is responsible for monitoring the temperature at the outlet of the heat exchange coil 13. When the temperature drops to 97K or lower, the system determines that the cooling effect has reached the expected level. Therefore, the opening degree of the electric regulating valve 112 is set to 10%, which helps to reduce the flow rate of liquid nitrogen, thereby avoiding overcooling and saving energy.

[0103] When the reading of the fifth temperature sensor T5 exceeds 97K, the opening of the electric regulating valve 112 increases linearly or exponentially. Specifically, when the temperature exceeds 97K, the system considers the cooling effect insufficient and needs to increase the flow rate of liquid nitrogen to further reduce the temperature. The opening of the regulating valve will increase linearly or exponentially according to the demand; the choice of growth method depends on the actual temperature rise of the system. If rapid cooling is required, an exponential growth method may be used; if only a small temperature increase is required, a linear growth method may be used for smooth control.

[0104] By adjusting the operating frequency of the blower 21 based on pollutant concentration, the system can save energy when air pollution is low and respond quickly when pollutant concentration increases, ensuring purification effectiveness. Furthermore, through precise control of the liquid nitrogen flow rate by the fifth temperature sensor T5, the system can avoid energy waste while ensuring cooling effectiveness, achieving a dynamic balance between energy saving and efficiency. Flexible adjustment of the blower 21 frequency and the opening of the electric regulating valve 112 enables the system to respond quickly to environmental changes and maintain the stability of the air purification and cooling process. This multi-variable collaborative control not only improves the system's automation level but also enhances its operational stability under different loads.

[0105] The control of the blower 21 and the electric regulating valve 112 maximizes system energy efficiency through dual monitoring of air pollutant concentration and temperature, employing flexible linear or exponential adjustment strategies. When air pollutant concentration is low or cooling reaches an ideal state, the system automatically reduces energy consumption. Conversely, when the load increases or the temperature rises, the system can quickly adjust to ensure air purification and cooling efficiency. This control strategy ensures both efficient system operation and rational energy utilization.

[0106] The control logic for starting the desorption operation is as follows: when the pressure difference between the incoming and outgoing air increases to twice the initial value, or the CO2 concentration difference between the incoming and outgoing air decreases to less than 30%, it is determined that pollutant desorption is required.

[0107] Specifically, when the pressure difference between the incoming and outgoing air increases to twice the initial value, it indicates that the amount of pollutants condensed inside the freezing chamber 12 and / or the regenerator 24 is large, the heat exchange channel of the regenerator 24 or the freezing chamber 12 is severely blocked, resulting in increased airflow resistance, and pollutant desorption is required.

[0108] When the CO2 concentration difference between the incoming and returning air decreases to less than 30%, it indicates a severe decline in pollutant purification efficiency, necessitating pollutant desorption.

[0109] The logic for determining the completion of desorption is as follows: when the detection values ​​of the second temperature sensor T2, the third temperature sensor T3, the fourth temperature sensor T4, and the sixth temperature sensor T6 are all greater than the detection value of the first temperature sensor T1 minus 3K, it is determined that the pollutant desorption is complete, and the blower 21 and the desorption heater 31 are turned off.

[0110] Specifically, the detection value of the first temperature sensor T1 is subtracted by 3K as a reference value. If the temperatures of the second temperature sensor T2, the third temperature sensor T3, the fourth temperature sensor T4, and the sixth temperature sensor T6 are all higher than this reference value, it indicates that the desorption heater 31 has heated the air in the closed circulation pipeline system to a sufficient temperature so that the solid pollutants can be completely vaporized and effectively desorbed.

[0111] The logic for determining the completion of the emission control is as follows: when the nitrogen concentration detected by the nitrogen concentration sensor X3 is greater than 99%, it is determined that the pollutant emission is complete. This indicates that the system has completely discharged the desorbed gaseous pollutants using nitrogen, and the main component of the remaining air is nitrogen. This high concentration of nitrogen is used to confirm that the pollutants have been completely discharged.

[0112] By comprehensively monitoring airflow pressure difference, CO2 concentration difference, and data from multiple temperature sensors, intelligent control of the pollutant desorption process is achieved. When the system detects conditions requiring desorption, it automatically initiates the desorption process; after desorption and pollutant emission are completed, the system automatically shuts down relevant equipment to save energy. Through this multi-parameter, multi-condition joint control, the system can efficiently and safely complete pollutant desorption and emission, improving the overall operational stability and reliability.

[0113] Compared to traditional purification technologies based on porous adsorbents, catalysts, etc., which can generally only treat pollutants of specific objects, the purification system and method disclosed in this invention adopts low-temperature freezing to achieve simultaneous liquefaction and freezing purification of multiple pollutants.

[0114] This invention enables automated continuous operation. By setting three operating conditions and configuring a series of electric shut-off valves and electric regulating valves 112, automated operation can be achieved with the support of control logic.

[0115] This invention eliminates the need for frequent filter or catalyst replacements; replenishment is only required when liquid nitrogen or nitrogen gas is depleted. Conventional air purification methods rely on adsorbents, filter media, or catalysts with limited lifespans, necessitating frequent replacements. This invention utilizes cryogenic freezing to capture air pollutants, avoiding the need for filter and catalyst replacements. Furthermore, replenishment is only required when liquid nitrogen or nitrogen gas is insufficient; both liquid nitrogen and nitrogen gas are readily available and inexpensive industrial products.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An air pollutant purification system, characterized in that, include: The refrigeration assembly (1) includes a liquid nitrogen container (11) and a freezing chamber (12). A heat exchange coil (13) is provided in the freezing chamber (12). The liquid nitrogen container (11) is connected to the inlet end of the heat exchange coil (13). The outlet end of the heat exchange coil (13) is connected to an exhaust assembly (14) for discharging used nitrogen gas to the outside of the system through the exhaust assembly (14). The air circulation assembly (2) includes a blower (21), a return air duct (22), a supply air duct (23), and a regenerator (24). The return air duct (22) is connected to the air inlet of the freezing chamber (12) through the regenerator (24) to allow the air to be purified to enter the freezing chamber (12) after passing through the regenerator (24) for freezing or liquefying gaseous pollutants. The air outlet of the freezing chamber (12) is connected to the supply air duct (23) through the regenerator (24). The blower (21) is connected in series with the supply air duct (23). The supply air duct (23) is used to send the purified air back to the control area. Desorption assembly (3) is used to remove solid contaminants from the low-temperature surfaces of the regenerator (24) and the freezing chamber (12); The emission component (4) is used to discharge the desorbed gaseous pollutants to the outside of the system.

2. The air pollutant purification system as described in claim 1, characterized in that: The regenerator (24) is provided with an air inlet channel (241) and a first heat exchange channel (242). The return air duct network (22) includes a return air duct (221), a return air outlet (224) and a second electric shut-off valve (223). The inlet end of the return air duct (221) is located in the return air zone and is connected to multiple return air outlets (224). The outlet end of the return air duct (221) is connected to the inlet of the air inlet channel (241). The outlet of the air inlet channel (241) is connected to the air inlet of the freezing chamber (12). The second electric shut-off valve (223) is provided on the return air duct (221). The air supply network (23) includes an air supply duct (231), a first electric shut-off valve (232), a flow meter (233), and an air outlet (234). The inlet end of the air supply duct (231) is connected to the outlet of the first heat exchange channel (242). The inlet of the first heat exchange channel (242) is connected to the air outlet of the freezing chamber (12). The outlet end of the air supply duct (231) is located in the air supply area and is connected to multiple air outlets (234). The blower (21), the first electric shut-off valve (232), and the flow meter (233) are sequentially arranged on the air supply duct (231) along the air flow direction of the air supply duct (231).

3. The air pollutant purification system as described in claim 2, characterized in that: The exhaust assembly (14) includes an exhaust pipe (141), an exhaust heater (142), a third electric shut-off valve (143), and a fourth electric shut-off valve (144). One end of the exhaust pipe is connected to the outlet end of the heat exchange coil (13), and the other end is used to connect to the external environment of the system. The exhaust heater (142), the third electric shut-off valve (143), and the third electric shut-off valve (144) are all arranged sequentially on the exhaust pipe (141) along the air flow direction of the exhaust pipe (141).

4. The air pollutant purification system as described in claim 3, characterized in that: It also includes a precooling pipeline (5), which includes a first pipeline (51), a second pipeline (52) and a fifth electric shut-off valve (53). The regenerator (24) is also provided with a second heat exchange channel (243). One end of the first pipeline (51) is connected to the outlet end of the heat exchange coil (13), and the other end is connected to the inlet of the second heat exchange channel (243). The fifth electric shut-off valve (53) is installed on the first pipeline (51). One end of the second pipeline (52) is connected to the outlet of the second heat exchange channel (243), and the other end is connected to the exhaust pipeline (141) between the third electric shut-off valve (143) and the fourth electric shut-off valve (144).

5. The air pollutant purification system as described in claim 4, characterized in that: The desorption assembly (3) includes a desorption heater (31), a desorption cross pipe (32), and a sixth electric shut-off valve (33). The two ends of the desorption cross pipe (32) are connected to the return air pipe (221) and the supply air pipe (231) respectively. The desorption heater (31) and the sixth electric shut-off valve (33) are both installed on the desorption cross pipe (32). The emission assembly (4) includes a purge pipe (41), a nitrogen container (42), a seventh electric shut-off valve (43), a third pipe (44), and an eighth electric shut-off valve (45). The nitrogen container (42) is connected to the air supply pipe (231) between the blower (21) and the regenerator (24) via the purge pipe (41). The seventh electric shut-off valve (43) is installed on the purge pipe (41). One end of the third pipe (44) is connected to the freezing chamber (12), and the other end is connected to the exhaust pipe (141) between the third electric shut-off valve (143) and the fourth electric shut-off valve (144). The eighth electric shut-off valve (45) is installed on the third pipe (44).

6. The air pollutant purification system as described in claim 5, characterized in that: The liquid nitrogen container (11) is connected to the inlet of the heat exchange coil (13) through a vacuum insulated pipe (111). An electric regulating valve (112) is also installed on the vacuum insulated pipe (111). A first temperature sensor (T1) is installed at the inlet of the return air pipe (221). A second temperature sensor (T2) is installed at the air inlet of the freezing chamber (12). A third temperature sensor (T3) is installed at the air outlet of the freezing chamber (12). A fourth temperature sensor (T4) is installed inside the freezing chamber (12). A fifth temperature sensor (T5) is installed at the outlet of the heat exchange coil (13). A sixth temperature sensor (T6) is installed at the inlet of the air supply pipe (231). The return air duct (221) is equipped with an incoming air pressure sensor (P1) and at least one incoming air pollutant concentration sensor (X1) at one end near the regenerator (24), the supply air duct (231) is equipped with a return air pressure sensor (P2) and at least one reverse air pollutant concentration sensor (X2) at one end near the regenerator (24), and a nitrogen concentration sensor (X4) is also installed on the third duct (44).

7. A method for purifying air pollutants, which utilizes the air pollutant purification system as described in claim 6, characterized in that, The steps include the following: S1, Cooling stage: Low-temperature nitrogen gas in liquid nitrogen container (11) is introduced into the heat exchange coil (13) of the freezing chamber (12) to provide a low-temperature cold source for the entire purification system; S2, Pre-cooling stage: After the blower (21) is started, the air to be purified in the environment is drawn into the return air duct (22) and enters the system, is transported to the regenerator (24), and then enters the freezing chamber (12) to exchange heat with the heat exchange coil (13) for cooling. The low temperature air leaves the freezing chamber (12) and enters the regenerator (24), which can cool the regenerator (24) body and the incoming air. At the same time, the temperature of the return air itself rises, leaves the regenerator (24), enters the air supply duct (23) and is transported to the air outlet (234) and returns to the environment. When the air temperature in the freezing chamber (12), the temperature of the regenerator body, the temperature of the return air and the temperature of the incoming air are all reduced to the rated operating point, the air purification stage is entered. S3, Air purification stage: The incoming air enters the freezing chamber (12) and exchanges heat with the heat exchange coil (13) to cool down. The gaseous pollutants in the air are liquefied and frozen on the surface of the heat exchange coil (13) and inside the freezing chamber (12), and the air is purified. S4. After the air purification stage has reached a certain time, the heater and freezing chamber (12) are heated by the desorption component (3) to desorb the pollutants. S5. After the pollutant desorption is completed, the air pollutants desorbed in the system are replaced by the emission component (4), and steps S1 to S4 are repeated.

8. The air pollutant purification method as described in claim 7, characterized in that: When the inlet temperature of the freezing chamber (12) is greater than 112K, the fourth electric shut-off valve (144) is opened, and a portion of the low-temperature precooled nitrogen is diverted through the fourth electric shut-off valve (144) to the first pipeline (51) and enters the regenerator (24) to accelerate the cooling process of the regenerator (24); when the inlet temperature of the freezing chamber (12) is less than or equal to 112K, the supply of low-temperature nitrogen from the precooling pipeline (5) to the regenerator (24) is stopped with respect to the fourth electric shut-off valve (144).

9. The air pollutant purification method as described in claim 7, characterized in that: When the incoming air pollutant concentration sensor (X1) detects a value less than the set target value, the operating frequency of the blower (21) is 10% of the rated air volume of the blower (21). When the incoming air pollutant concentration sensor (X1) detects a value less than 20% of the set target value, the operating frequency of the blower (21) increases exponentially. When the incoming air pollutant concentration sensor (X1) detects a value greater than 20% of the set target value, the operating frequency of the blower (21) increases linearly. When the detection value of the fifth temperature sensor (T5) is less than or equal to 97K, the opening degree of the electric regulating valve (112) is 10% of the rated opening degree. When the detection value of the fifth temperature sensor (T5) is greater than 97K, the opening degree of the electric regulating valve (112) increases linearly or exponentially.

10. The air pollutant purification method as described in claim 7, characterized in that: When the pressure difference between the incoming and outgoing air increases to twice the initial value, or the CO2 concentration difference between the incoming and outgoing air decreases to less than 30%, it is determined that pollutant desorption is required. When the detection values ​​of the second temperature sensor (T2), the third temperature sensor (T3), the fourth temperature sensor (T4), and the sixth temperature sensor (T6) are all greater than the detection value of the first temperature sensor (T1) minus 3K, it is determined that the pollutant desorption is completed, and the blower (21) and the desorption heater (31) are turned off. When the nitrogen concentration detected by the nitrogen concentration sensor (X4) is greater than 99%, it is determined that the pollutant emission is completed.

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