A recovery system for high concentration n-methylisopropylamine exhaust gas

Abstract

The utility model discloses a kind of recovery treatment systems of high concentration N-methyl isopropylamine waste gas, including water absorption tower, acid absorption tower, dehumidifier, dry filter and adsorption bed connected in sequence, molecular sieve adsorbent is equipped in the adsorption bed.The utility model system simple structure, to high concentration N-methyl isopropylamine waste gas treatment effect is good, can be well recovered N-methyl isopropylamine, and treated waste gas can meet emission standard again, can be directly discharged.

Description

Technical Field

[0001] This utility model relates to a waste gas recovery and treatment system, specifically a waste gas recovery and treatment system for high-concentration N-methylisopropylamine waste gas. Background Technology

[0002] N-Methylisopropylamine is a raw material for the synthesis of herbicides, and it is generally added in excess during the herbicide synthesis process. N-Methylisopropylamine has a low boiling point (only 42.98 ℃) and is highly volatile. At 0 ℃, the saturation partial pressure of N-methylisopropylamine is 11.9 kPa, and the saturation concentration is 382.3 g / m³. Therefore, the synthesis process generates waste gas containing a high concentration of N-methylisopropylamine. N-Methylisopropylamine has certain recovery value; therefore, this waste gas needs to first recover the N-methylisopropylamine and then treat it to meet emission requirements before being released.

[0003] Currently, there is no existing technology for treating N-methylisopropylamine waste gas. CN202220931110.X discloses a multi-stage spray absorption device for dimethylamine waste gas, which mainly uses hydrochloric acid to absorb dimethylamine and employs a multi-stage circulating spray device for recovery. CN201520588053.X discloses a pentanediamine waste gas absorption and treatment device, which uses dilute acid to neutralize pentanediamine, with the resulting ammonium salt crystals as a byproduct. However, because N-methylisopropylamine has a high saturation partial pressure at room temperature, its saturation concentration can reach 382.3 g / m³. Even with a 99% absorption efficiency, the concentration of N-methylisopropylamine after water absorption treatment still reaches 3.82 g / m³, which cannot effectively achieve the goal of direct discharge after treatment.

[0004] In addition, existing technologies also include resin adsorption and RTO incineration for treating waste gas. Resin adsorption is difficult to regenerate, requires high energy consumption, and its adsorption performance declines after repeated use. Furthermore, resin adsorption has poor selectivity; hydrophobic resins may struggle to effectively adsorb the highly polar N-methylisopropylamine, and other VOCs in the waste gas may compete with N-methylisopropylamine for adsorption sites. Moreover, because N-methylisopropylamine has a low boiling point, it is prone to spontaneous desorption after resin adsorption in high-temperature environments (e.g., summer). RTO incineration requires high influent gas concentrations; if the N-methylisopropylamine concentration in the treated waste gas is high, it will combine with chlorine-containing acidic substances to form ammonium salts, clogging the heat storage ceramic. Utility Model Content

[0005] To address the shortcomings of existing technologies for treating high-concentration N-methylisopropylamine waste gas, this invention provides a high-concentration N-methylisopropylamine waste gas recovery and treatment system. This system specifically recovers N-methylisopropylamine from the waste gas, and the treated waste gas can be directly discharged in compliance with standards. The waste gas treatment cost is low, and it is easy to apply industrially.

[0006] The specific technical solution of this utility model is as follows: A high-concentration N-methylisopropylamine waste gas recovery and treatment system includes a water absorption tower, an acid absorption tower, a dehumidifier, a dry filter, and an adsorption bed connected in sequence. The adsorption bed consists of two sets: one for adsorption and the other for desorption. Each adsorption bed includes an inlet, an outlet, a desorption medium inlet, and a desorption medium outlet. During adsorption, the inlet of the adsorption bed is connected to the dry filter, and the outlet is connected to a chimney via a pipe. During desorption, the desorption medium inlet of the adsorption bed is connected to the cold-side outlet of a secondary heat exchanger, and the desorption medium outlet is connected to the cold-side inlet of a primary heat exchanger via a first pipe. The cold-side outlet of the primary heat exchanger is connected to the inlet of a catalytic combustion furnace. The exhaust port of the catalytic combustion furnace is connected to the hot-side inlet of the primary heat exchanger via a second pipe, and simultaneously connected to the hot-side inlet of the secondary heat exchanger via a third pipe. The hot-side outlet of the primary heat exchanger is connected to the third pipe via a fourth pipe.

[0007] Furthermore, the first pipe is provided with a fresh air inlet, the cold side inlet of the secondary heat exchanger is used to introduce fresh air, and the hot side outlet of the secondary heat exchanger is connected to the chimney.

[0008] Furthermore, the adsorption bed is provided with a molecular sieve adsorbent.

[0009] Furthermore, the water absorption tower is equipped with a spraying device, and a water storage tank is connected to the bottom of the water absorption tower. The outlet of the water storage tank is connected to the spraying device through a pipe, and a water circulation pump is installed on the pipe.

[0010] Furthermore, the acid absorption tower is equipped with a spraying device, and an acid storage tank is connected to the bottom of the acid absorption tower. The outlet of the acid storage tank is connected to the spraying device through a pipe, and an acid circulation pump is installed on the pipe.

[0011] Furthermore, the spraying device is a spray head.

[0012] Furthermore, a blower is connected between the acid absorption tower and the dehumidifier.

[0013] Furthermore, the adsorption bed consists of two sets, one for adsorption and the other for desorption. The two sets of adsorption beds are used alternately, operating according to the principle of "one adsorption, one desorption".

[0014] Furthermore, a PID detector (photoionization gas detector) is installed on the pipe connecting the gas outlet of the adsorption bed to the chimney to detect the condition of the gas after adsorption.

[0015] Furthermore, a fan is installed on the pipe connecting the gas outlet of the adsorption bed to the chimney to discharge the adsorbed gas into the chimney.

[0016] Furthermore, a temperature and humidity sensor is installed at the outlet of the dehumidifier.

[0017] Furthermore, the filter medium in the dry filter is fiber, which has the characteristics of antistatic properties, flame retardancy, and large dust holding capacity. The dry filter is equipped with differential pressure monitoring. This differential pressure monitoring is mainly achieved through pressure sensors installed before and after the dry filter, at the air inlet and outlet ends. By monitoring the pressure difference before and after the dry filter, the filter's clogging status is reflected in real time, thereby determining whether the filter media needs to be replaced.

[0018] This utility model has the following beneficial effects: 1. This utility model addresses the challenge of N-methylisopropylamine having a high saturation partial pressure at room temperature and leaving a significant residue after water and acid absorption. By installing a dehumidifier, a dry filter, and an adsorption bed after the water and acid absorption towers, it ensures the full recovery and removal of N-methylisopropylamine. The gas discharged through the adsorption bed meets the standards for direct emission.

[0019] 2. This utility model employs two sets of adsorption beds, namely adsorption bed A and adsorption bed B, operating according to the principle of "one adsorption and one desorption". When adsorption bed A needs regeneration, adsorption stops and desorption is performed, and adsorption bed B is used for adsorption. Similarly, when adsorption bed B needs desorption, adsorption bed A is used for adsorption. The two sets of adsorption beds are switched in a cycle through valves, ensuring continuous and efficient waste gas treatment.

[0020] 3. The waste gas after desorption from the adsorption bed in this invention is incinerated in a catalytic combustion furnace. Under the catalysis of the catalyst, the organic matter in the waste gas is converted into carbon dioxide, water, and nitrogen at a relatively low temperature, without generating nitrogen oxides, thus exhibiting good environmental performance. Furthermore, heat exchangers are installed at the front and rear ends of the catalytic combustion furnace to ensure full heat recovery, reducing costs and energy consumption.

[0021] 4. The system of this utility model has a simple structure and a good effect on treating high-concentration N-methylisopropylamine waste gas. It can not only recover N-methylisopropylamine well, but also ensure that the treated waste gas meets the emission standards and can be directly discharged. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the high-concentration N-methylisopropylamine waste gas recovery and treatment system of this utility model.

[0023] 0. Reactor; 1. Water absorption tower; 2. Acid absorption tower; 3. Dehumidifier; 4. Dry filter; 5-a. Adsorption bed A; 5-b. Adsorption bed B; 6. Primary heat exchanger; 7. Catalytic combustion furnace; 8. Secondary heat exchanger; 9. Check valve; 10. Water storage tank; 11. Water circulation pump; 12. Acid storage tank; 13. Acid circulation pump; 14. Blower; 15. Desorption blower; 16. Main blower; 17. PID detector; 18. Chimney; 19. First pipe; 20. Second pipe; 21. Third pipe; 22. Fourth pipe; 23. Fresh air inlet; 24. Cold side inlet of secondary heat exchanger. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of the present utility model are only used to explain the relative positional relationship and movement of the components in a certain posture (as shown in the accompanying drawings). If the specific posture changes, the directional indicator will also change accordingly. In addition, the technical solutions of the various embodiments can be combined with each other, but it must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present utility model.

[0025] Example 1 A system for recovering and treating high-concentration N-methylisopropylamine waste gas, such as... Figure 1As shown, the system includes a water absorption tower 1, an acid absorption tower 2, a dehumidifier 3, a dry filter 4, an adsorption bed, a heat exchanger, and a catalytic combustion furnace 7. The water absorption tower, acid absorption tower, dehumidifier, dry filter, and adsorption bed are connected in sequence. The lower part of the water absorption tower has an air inlet connected to the air outlet of the reaction vessel 0. Waste gas generated in the reaction vessel enters the water absorption tower through a one-way valve 9. The bottom of the water absorption tower has a liquid outlet connected to a water storage tank 10. The water storage tank initially contains water, which, after multiple cycles, becomes water-absorbing liquid. A spray device is installed inside the water absorption tower, preferably located at the top. The outlet of the water storage tank is connected to the spray device via a pipe. A water circulation pump 11 is installed on the pipe between the water storage tank and the spray device, pumping water or water-absorbing liquid from the water storage tank into the spray device. The water absorption tower has an outlet at the top, which is connected to the inlet of the acid absorption tower. The inlet of the acid absorption tower is located at its lower part. Like the water absorption tower, the acid absorption tower has a liquid outlet at the bottom, an internal spray device, and an outlet at the top. The spray device is preferably located at the top of the acid absorption tower. The liquid outlet of the acid absorption tower is connected to an acid storage tank 12. The acid storage tank is connected to the spray device via a pipeline, and an acid circulation pump 13 is installed on the pipeline. The acid solution in the acid storage tank is pumped into the spray device by the acid circulation pump. For example, the acid solution in the acid storage tank is a sulfuric acid solution, and the concentration of the sulfuric acid solution can be 10wt%~20wt%.

[0026] Furthermore, the spray devices in water absorption towers and acid absorption towers are used to spray water or acid into the absorption tower for the absorption of waste gas. The spray devices can be spray heads, nozzles, etc., and there can be multiple spray heads or nozzles.

[0027] The outlet of the acid absorption tower is connected to the inlet of the dehumidifier via a blower 14. The outlet of the dehumidifier is connected to the inlet of the dry filter, and the outlet of the dry filter is connected to the adsorption bed. Both the dehumidifier and the dry filter are commercially available products. The dehumidifier housing is made of 316L stainless steel or PP material to prevent corrosion and leakage. The dehumidifier is used to control the humidity and temperature of the exhaust gas. The filter media in the dry filter is fiber or other filter media, such as glass fiber. The dry filter is used to remove particulate matter that may be present in the exhaust gas. Through the selection of the filter media, the dry filter ensures a rejection efficiency of ≥95% for particles larger than 1 μm.

[0028] The adsorption bed consists of two sets, namely adsorption bed A and adsorption bed B. Adsorption beds A and B have identical structures, both containing molecular sieve adsorbents, such as zeolite molecular sieve adsorbents. The two sets of adsorption beds are used alternately, operating according to the principle of "one adsorption, one desorption". Each adsorption bed includes an inlet (for the waste gas to be adsorbed), an outlet (for the gas that has met the standards after adsorption treatment), a desorption medium inlet (for connecting the desorption medium during desorption), and a desorption medium outlet (for discharging the desorbed waste gas).

[0029] The primary heat exchanger 6 and the secondary heat exchanger 8 are used for heat exchange to reduce energy consumption. Both the primary and secondary heat exchangers include a hot-side inlet, a hot-side outlet, a cold-side inlet, and a cold-side outlet. The functions of each inlet and outlet of the primary heat exchanger are as follows: (1) Hot-side inlet: connected to the exhaust port of the catalytic combustion furnace, and connected to a portion of the high-temperature purified gas; (2) Hot-side outlet: the high-temperature purified gas is cooled down after releasing heat in the primary heat exchanger and is discharged here to mix with the high-temperature purified gas discharged from the catalytic combustion furnace and enter the secondary heat exchanger for heat exchange; (3) Cold-side inlet: connected to the mixture of high-concentration waste gas after desorption and fresh air; (4) Cold-side outlet: the mixture of high-concentration waste gas after desorption and fresh air is heated by heat exchange with the high-temperature purified gas and then discharged here to enter the catalytic combustion furnace. The functions of each inlet and outlet of the secondary heat exchanger are as follows: (1) Hot side inlet: Inlet for part of the high-temperature purified gas discharged from the catalytic combustion furnace and the purified gas that has been heated by the primary heat exchanger; (2) Hot side outlet: After the high-temperature purified gas releases heat in the secondary heat exchanger, it cools down and is discharged through the desorption fan 15 and discharged through the chimney; (3) Cold side inlet: Inlet for fresh air; (4) Cold side outlet: After the fresh air is preheated in the secondary heat exchanger, it is discharged through this outlet and enters the adsorption bed for desorption.

[0030] Furthermore, the air inlet of the adsorption bed is connected to a dry filter, and the air outlet is connected to the chimney 18 via a pipe to complete the adsorption process. The desorption medium inlet of the adsorption bed is connected to the cold-side outlet of the secondary heat exchanger, and the desorption medium outlet of the adsorption bed is connected to the cold-side inlet of the primary heat exchanger via a first pipe 19. A fresh air inlet 23 is provided on the first pipe. The cold-side outlet of the primary heat exchanger is connected to the inlet of the catalytic combustion furnace 7. The exhaust port of the catalytic combustion furnace is connected to the hot-side inlet of both the primary and secondary heat exchangers. The exhaust port is connected to the hot-side inlet of the primary heat exchanger via a second pipe 20, and to the hot-side inlet of the secondary heat exchanger via a third pipe 21. The hot-side outlet of the primary heat exchanger is connected to the third pipe via a fourth pipe 22. The cold-side inlet 24 of the secondary heat exchanger is used to introduce fresh air, and the hot-side outlet of the secondary heat exchanger is connected to the chimney. The adsorption bed, primary heat exchanger, secondary heat exchanger, and catalytic combustion furnace are connected to achieve desorption in the adsorption bed.

[0031] Furthermore, a PID detector 17 (photoionization gas detector) is installed on the pipe connecting the gas outlet of the adsorption bed to the chimney for VOCs concentration detection. The VOCs concentration of the adsorbed gas must meet the emission requirements in GB 16297-1996 Integrated Emission Standard for Air Pollutants.

[0032] Furthermore, a main fan 16 is installed on the pipe connecting the gas outlet of the adsorption bed to the chimney to discharge the adsorbed gas into the chimney.

[0033] Furthermore, the catalytic combustion furnace is heated by an internal electric heating system, with the combustion temperature controlled within the range of 250~400 ℃. The catalyst in the catalytic combustion furnace is a non-precious metal catalyst (copper, manganese oxides, etc.). The catalytic combustion furnace can be commercially available and can be customized in separate parts or skid-mounted as a whole, depending on the actual air volume. The catalytic combustion furnace generally consists of core structural components such as a shell (composed of a steel frame and insulation material), a preheating chamber, an electric heating system, and a catalytic reaction chamber (containing a catalyst bed). The catalyst in the combustion furnace is not in powder form, but is fixed on the catalyst bed in a regular structure, using a standard cordierite honeycomb carrier to support precious metals. The electric heating system is installed before the inlet of the catalytic reaction chamber, i.e., in the preheating chamber, and uses U-shaped or flange-type electric heating tubes.

[0034] Example 2 A high-concentration N-methylisopropylamine waste gas recovery and treatment system is described in the same way as in Example 1. Furthermore, a temperature and humidity sensor is installed at the dehumidifier outlet to monitor the humidity and temperature of the gas discharged from the dehumidifier. This dehumidifier is a refrigeration dehumidifier, consisting of a compressor, heat exchanger, fan, casing, and controller. Its working principle involves the fan drawing humid air into the machine, where it condenses into frost through the interaction of the refrigeration system (compressor, evaporator, and condenser). The system automatically heats up to defrost the frost, which then flows into a water tank, producing dry air for discharge. After dehumidification, the outlet air humidity (RH) is ≤60% and the outlet air temperature is ≤50℃. A differential pressure monitoring device is installed on the dry filter to monitor in real time whether the filter media needs to be replaced. The filter media needs to be replaced when the differential pressure is ≥500 Pa. The differential pressure monitoring system is mainly installed before and after the dry filter, using a pressure sensor (differential pressure sensor). This sensor is a commercially available, mature product that can monitor the pressure difference before and after the filter in real time and transmit the switch signal to the control system.

[0035] Furthermore, the recycling system of this utility model also includes an electrical control system, which is connected to the pressure sensor of the dry filter, the temperature and humidity sensor at the outlet of the dehumidifier, the electric heater in the heat exchanger, the PID gas detector, etc.

[0036] Example 3 The recovery and treatment systems of Examples 1 and 2 described above can be used for the recovery and treatment of high-concentration N-methylisopropylamine waste gas, which refers to waste gas with an N-methylisopropylamine concentration of 100 g / m³ or higher. Due to the high N-methylisopropylamine concentration in this waste gas, water or acid absorption alone cannot meet emission requirements. The operating procedure and process conditions of this utility model's recovery and treatment system for treating this type of waste gas are as follows: 1. The reactor is started, generating N-methylisopropylamine waste gas. This waste gas enters the bottom of the water absorption tower through a one-way valve. Simultaneously, the water circulation pump is started, pumping the water absorption liquid from the storage tank into the spray device. Through circulation by the water circulation pump, the N-methylisopropylamine in the waste gas is absorbed, achieving the effect of water absorption treatment. The treated waste gas then enters the acid absorption tower, which is equipped with a spray device. The acid absorption liquid can be sulfuric acid with a concentration of 10wt%~20wt%. The acid absorption liquid is circulated from the acid storage tank through the acid circulation pump and sprayed into the acid absorption tower by the spray device, achieving the effect of acid absorption treatment. Utilizing the water-soluble property of N-methylisopropylamine, the high-concentration N-methylisopropylamine waste gas generated by the reactor is treated by water absorption to recover N-methylisopropylamine. A primary acid absorption stage is set up after water absorption. If the primary water absorption stage breaks through, the acid absorption tower can prevent leakage of N-methylisopropylamine waste gas after the water absorption stage becomes saturated. After the absorbent liquid after water absorption becomes saturated, N-methylisopropylamine can be recovered by distillation.

[0037] The water absorption process requires controlling the liquid-to-gas ratio (the ratio of water circulation pump flow rate to inlet air flow rate, in L / m³). A liquid-to-gas ratio in the range of 5–20 L / m³ results in optimal water absorption. Similarly, the acid absorption process also requires controlling the liquid-to-gas ratio (the ratio of acid circulation pump flow rate to inlet air flow rate, in L / m³). A liquid-to-gas ratio in the range of 3–15 L / m³ results in optimal water absorption.

[0038] 2. After acid absorption treatment, the exhaust gas enters a dehumidifier via a blower for dehumidification. A temperature and humidity sensor is installed at the dehumidifier outlet to control the outlet humidity (RH) to ≤60% and the outlet temperature to ≤50℃. The dehumidified exhaust gas then enters a dry filter to filter out fine particulate matter. The outlet particle size of the dry filter is ≤10 mg / m³, ensuring a filter retention efficiency of ≥95% for particles larger than 1 μm. Particulate matter retention is achieved through a multi-stage filtration structure. Pressure sensors are installed at the inlet and outlet of the dry filter to monitor in real time whether the filter media needs replacement. The filter media must be replaced when the pressure difference is ≥500 Pa.

[0039] 3. Adsorption bed A and adsorption bed B operate alternately according to the principle of "one adsorption and one desorption". When the adsorption capacity of the zeolite molecular sieve in the adsorption bed drops to 80%, it needs to be regenerated by desorption.

[0040] Taking "A-bed adsorption, B-bed desorption" as an example, the adsorption process is as follows: the waste gas filtered by the dry filter enters the inlet of adsorption bed A, the VOCs in the waste gas are adsorbed in adsorption bed A, the purified gas is discharged from the outlet of adsorption bed A, and after passing the photoionization gas detector (PID gas detector), it is discharged from the chimney.

[0041] The desorption process is a closed-loop heat recovery system. Fresh air first enters the cold-side inlet of the secondary heat exchanger, where it is heated to the desorption temperature by an internal electric heater. The heated, high-temperature air then enters the desorption medium inlet of adsorption bed B as the desorption medium. The high-temperature gas blows the adsorbent in the opposite direction (relative to the adsorption direction), removing the enriched pollutants and forming a high-concentration, low-volume desorbed waste gas. This waste gas exits from the desorption medium outlet of adsorption bed B, mixes with fresh air in the first pipe, enters the cold-side inlet of the primary heat exchanger, and exits from the cold-side outlet into the catalytic combustion furnace. In the catalytic combustion furnace, the air is heated to the catalytic combustion temperature, causing the VOCs in the waste gas to be catalytically combusted into harmless gases such as carbon dioxide, nitrogen, and water. A portion of the high-temperature harmless gas in the catalytic combustion furnace enters the hot-side inlet of the secondary heat exchanger to exchange heat with fresh air. The cooled harmless gas is then discharged into the chimney from the hot-side outlet of the secondary heat exchanger by the desorption fan. Another portion of the high-temperature harmless gas in the catalytic combustion furnace enters the hot-side inlet of the primary heat exchanger to exchange heat with the waste gas mixture in the primary heat exchanger, preheating the waste gas and reducing heating costs. The heated waste gas is then discharged into the catalytic combustion furnace from the cold-side outlet of the primary heat exchanger. The cooled harmless gas mixes with the high-temperature harmless gas entering the secondary heat exchanger and enters the secondary heat exchanger, thereby achieving desorption of adsorption bed B.

[0042] The desorption temperature is 120~140℃. The secondary heat exchanger has an internal electric heater. If the high-temperature, harmless gas discharged from the catalytic combustion furnace is insufficient to heat the air in the secondary heat exchanger to 120~140℃, the electric heater is needed to simultaneously heat the fresh air. Through the primary and secondary heat exchangers, heat is fully recovered, avoiding heat loss and reducing costs. The entire desorption time is controlled within 1-2 hours, and the adsorption bed can be reused after natural cooling.

[0043] When bed B adsorbs and bed A desorbs, adsorption bed B is connected to the dry filter according to the adsorption connection method, and adsorption bed A is connected to the primary heat exchanger and the secondary heat exchanger according to the desorption connection method.

Claims

1. A system for recovering and treating high-concentration N-methylisopropylamine waste gas, characterized in that: The system comprises a water absorption tower, an acid absorption tower, a dehumidifier, a dry filter, and an adsorption bed connected in sequence. The adsorption bed consists of two sets: one for adsorption and one for desorption. Each adsorption bed includes an air inlet, an air outlet, a desorption medium inlet, and a desorption medium outlet. During adsorption, the air inlet of the adsorption bed is connected to the dry filter, and the air outlet is connected to a chimney via a pipe. During desorption, the desorption medium inlet of the adsorption bed is connected to the cold-side outlet of the secondary heat exchanger, and the desorption medium outlet of the adsorption bed is connected to the cold-side inlet of the primary heat exchanger via a first pipe. The cold-side outlet of the primary heat exchanger is connected to the inlet of the catalytic combustion furnace. The exhaust port of the catalytic combustion furnace is connected to the hot-side inlet of the primary heat exchanger via a second pipe, and simultaneously, the exhaust port is connected to the hot-side inlet of the secondary heat exchanger via a third pipe. The hot-side outlet of the primary heat exchanger is connected to the third pipe via a fourth pipe.

2. The recycling system according to claim 1, characterized in that: The first pipe is provided with a fresh air inlet, the cold side inlet of the secondary heat exchanger is used to introduce fresh air, and the hot side outlet of the secondary heat exchanger is connected to the chimney.

3. The recycling system according to claim 1 or 2, characterized in that: The adsorption bed contains a molecular sieve adsorbent.

4. The recycling system according to claim 1, characterized in that: The water absorption tower is equipped with a spraying device. A water storage tank is connected to the bottom of the water absorption tower. The outlet of the water storage tank is connected to the spraying device through a pipe, and a water circulation pump is installed on the pipe.

5. The recycling system according to claim 1, characterized in that: The acid absorption tower is equipped with a spraying device, and an acid storage tank is connected to the bottom of the acid absorption tower. The outlet of the acid storage tank is connected to the spraying device through a pipe, and an acid circulation pump is installed on the pipe.

6. The recycling system according to claim 4 or 5, characterized in that: The spraying device is a nozzle.

7. The recycling system according to claim 1, characterized in that: A blower is connected between the acid absorption tower and the dehumidifier.

8. The recycling system according to claim 1, characterized in that: A temperature and humidity sensor is installed at the outlet of the dehumidifier.

9. The recycling system according to claim 1, characterized in that: Pressure sensors are installed at the inlet and outlet of the dry filter.

10. The recycling system according to claim 1, characterized in that: A photoionization gas detector is also installed on the pipe connecting the gas outlet of the adsorption bed to the chimney.

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