Waste gas adsorption and recovery system

Abstract

The waste gas adsorption and recovery system comprises a temperature and humidity adjusting device, a concentration buffer device and an adsorber which are connected in sequence, the adsorber comprises a first bed layer arranged close to the waste gas inlet and a second bed layer arranged close to the waste gas outlet; the first bed layer comprises an adsorption material with a porous structure and a first specific surface area, and the second bed layer comprises a microporous adsorption material with a second specific surface area; the first specific surface area is larger than the second specific surface area; the thickness of the first bed layer accounts for 50%-80% of the whole bed layer, and the thickness of the second bed layer accounts for 20%-50% of the whole bed layer. The adsorber is designed into two types of adsorption materials, the adsorption inlet side of the adsorber is made of a high-specific-surface porous structure adsorption material, and the adsorption outlet side of the adsorber is made of a small-specific-surface uniform microporous adsorption material. The bed thickness of each adsorption material can be adjusted, and the bed proportion of different materials can be adjusted according to the requirement of outlet concentration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial waste gas treatment, more particularly to a waste gas adsorption recovery system. BACKGROUND

[0002] The waste gas discharged in the drying and coating process of the printing industry, fiber industry, resin industry and other fields generally has a concentration of 2-10 g / m 3 , and needs to be treated for environmental protection. The common treatment technologies on the market mainly include incineration process and solvent recovery process. In the range of the inlet concentration of the waste gas, the adsorption recovery process is a more suitable solvent recovery technology, and the adsorption and desorption recovery process using nitrogen as the desorption medium does not produce waste water and secondary pollution; the recovered solvent has a lower water content and higher quality; and the application range is wider, so the adsorption and desorption recovery process has been widely applied in the market.

[0003] At the same time, the environmental protection requirements of the country are becoming more and more stringent, and local emission standards have been introduced in various places across the country. Many places require VOCs to meet 50-60 mg / m 3 , and individual characteristic pollutants to meet 20 mg / m 3 or below. The adsorption and desorption recovery process using nitrogen as the desorption medium needs to meet more stringent emission standards and has higher requirements for purification efficiency. At the same time, reducing the operating energy consumption and investment cost of the system is also the strong demand of enterprises.

[0004] For the nitrogen desorption process, the desorption hot nitrogen containing solvent is condensed and recovered by a condenser during desorption. However, the saturation concentration of the waste gas after condensation is generally high, and relying solely on condensation will cause a large amount of high-concentration solvent to remain in the activated carbon tank. If the activated carbon tank is adsorbed again, the residual solvent will be directly discharged into the atmosphere, resulting in an unqualified outlet concentration. The patents CN206444409U, CN111318128A and CN219897572U all propose corresponding solutions. Although the above patent solutions solve the problem of meeting the standards to some extent, there are still the following problems:

[0005] 1. The addition of a secondary activated carbon adsorption bed on the desorption pipeline not only complicates the process route and increases the investment cost, but also leads to low desorption recovery rate and high operating cost.

[0006] 2. The adsorption of a molecular sieve rotor in series after the original activated carbon adsorption tank, although the purification efficiency is higher and can meet higher emission standards, the molecular sieve rotor needs to be desorbed again, which increases the desorption energy consumption by 10%-20% and also increases the investment cost due to the additional equipment. SUMMARY

[0007] The application aims to provide a waste gas adsorption recovery system with simple process, high purification efficiency and low cost.

[0008] The application provides a waste gas adsorption recovery system, comprising:

[0009] The temperature and humidity adjusting device, the concentration buffering device and the adsorber are connected in sequence.

[0010] The adsorber comprises a first bed layer arranged close to the waste gas inlet and a second bed layer arranged close to the waste gas outlet; the first bed layer comprises a first adsorption material, and the second bed layer comprises a second adsorption material.

[0011] The first adsorption material is a porous structure adsorption material with a first specific surface area; and / or, the second adsorption material is a microporous adsorption material with a second specific surface area; the value of the first specific surface area is greater than the value of the second specific surface area.

[0012] The thickness of the first bed layer accounts for 50% to 80% of the entire bed layer, and the thickness of the second bed layer accounts for 20% to 50% of the entire bed layer.

[0013] Optionally, a plurality of adsorbers are arranged in parallel.

[0014] Optionally, the bottom and the top of the adsorber are respectively provided with a nitrogen inlet and a displacement gas outlet, and the nitrogen inlet is provided with a heating device to heat the gas entering from the nitrogen inlet.

[0015] The waste gas adsorption recovery system further comprises a desorption unit and an oxygen concentration detector arranged at the displacement gas outlet.

[0016] The nitrogen inlet can be used to introduce nitrogen to purge the first bed layer and the second bed layer, so as to displace the gas containing oxygen and VOCs in the adsorber.

[0017] The displacement gas outlet is connected to the waste gas inlet through a pipeline, and the desorption unit is connected to the displacement gas outlet.

[0018] Optionally, the oxygen concentration detector comprises a first oxygen concentration detector and a second oxygen concentration detector arranged in series.

[0019] Optionally, the desorption unit comprises a heat exchanger with an adsorption structure, a condenser and a layered tank.

[0020] The hot inlet of the heat exchanger is connected to the displacement gas outlet, the gas enters the heat exchanger from the hot inlet, and then enters the condenser from the cold outlet of the heat exchanger to be condensed, and the condensed liquid enters the layered tank; the condensed gas flows back to the heat exchanger from the cold inlet of the heat exchanger, exchanges heat with the gas entering the heat exchanger from the hot inlet of the heat exchanger, and then flows back to the nitrogen inlet from the hot outlet of the heat exchanger.

[0021] Optionally, the condenser comprises a first condenser and a second condenser arranged in series on the cold outlet side of the heat exchanger.

[0022] Optionally, the first condenser uses circulating water as the condensing medium, and / or the second condenser uses chilled water as the condensing medium.

[0023] Optionally, the heat exchanger comprises a full-effect heat exchanger; the full-effect heat exchanger comprises a fixed-bed heat exchanger or a rotary structure heat exchanger coated with adsorbent material.

[0024] Optionally, the waste gas adsorption recovery system further comprises a desorption fan, the air inlet side of the desorption fan is connected with the hot outlet, the air outlet side of the desorption fan is connected with the air inlet side of the heating device, and the air outlet side of the heating device is connected with the nitrogen inlet.

[0025] Optionally, the concentration buffer device comprises a cylindrical concentration buffer adsorbent material or a flat concentration buffer adsorbent material, and the specific surface area of the concentration buffer adsorbent material is greater than or equal to 1200 m2 / g.

[0026] According to the technical content disclosed in the present application, the following beneficial effects are achieved:

[0027] The waste gas adsorption recovery system provided by the present application comprises a temperature and humidity adjusting device, a concentration buffer device and an adsorber connected in sequence; the temperature of the gas is adjusted to 30-40 DEG C in the temperature and humidity adjusting device, and then the mixed gas of the waste gas discharged from the workshop and the waste gas generated in the replacement and desorption process is balanced in the concentration buffer device, so that the concentration of the mixed gas is balanced within a certain range, and the outlet concentration of the treated gas is relatively stable. The mixed gas enters the adsorber for treatment, the adsorber comprises a first bed layer arranged near the waste gas inlet and a second bed layer arranged near the waste gas outlet; the first bed layer comprises a first adsorbent material, and the second bed layer comprises a second adsorbent material; the first adsorbent material is a porous structure adsorbent material with a first specific surface area, which mainly ensures the adsorption capacity of the adsorption process and ensures that the adsorption time meets the design requirements; the second adsorbent material is a microporous adsorbent material with a second specific surface area; the value of the first specific surface area is greater than the value of the second specific surface area, which mainly ensures the purification efficiency of the adsorption process and ensures that the outlet concentration meets the design emission standard. The thickness of the first bed layer accounts for 50%-80% of the entire bed layer, and the thickness of the second bed layer accounts for 20%-50% of the entire bed layer. The design of the bed layer structure mainly ensures that the high-concentration waste gas remaining after the desorption of the adsorber does not need to be additionally increased by a secondary adsorption bed or a molecular sieve rotary device, and the outlet concentration of the waste gas after being adsorbed by the adsorber can reach 5 mg / m 3 ~ 50 mg / m 3 The different heights of the first bed layer and the second bed layer can be adjusted to meet the requirements of different outlet concentrations.

[0028] Other features of the present application, its nature and advantages will become apparent from the following detailed description of the exemplary embodiments of the application, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0030] Figure 1 The figure is a schematic diagram of the exhaust gas adsorption recovery system of the present application. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present application will now be described in detail with reference to the figures. Note that the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments are not limiting to the scope of the present application unless otherwise specifically stated.

[0032] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way limiting to the scope of the application or its applications or uses.

[0033] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, such techniques, methods, and apparatus can be considered as part of the description of the present application.

[0034] In all of the examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not limiting. Thus, other examples of the exemplary embodiments can have different values.

[0035] It should be noted that like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it is not necessary to discuss it further in subsequent drawings.

[0036] Referring to Figure 1 The present application discloses an exhaust gas adsorption recovery system for treating plant exhaust gas P1 generated in a plant, which comprises an adsorption unit and a desorption unit. The adsorption unit is mainly used for adsorbing the plant exhaust gas generated in the plant, and the desorption unit is mainly used for desorbing the adsorber of the adsorption unit.

[0037] The adsorption unit comprises a temperature and humidity adjusting device 1, a concentration buffer device 2, an adsorption fan 3 and an adsorber connected in sequence, wherein the adsorber comprises a first adsorber TA and a second adsorber TB connected in parallel in the embodiment, the bottom of the first adsorber TA is provided with a nitrogen inlet 101 and a waste gas inlet 103, the top of the first adsorber TA is provided with a displacement gas outlet 102 and a waste gas outlet 104; the second adsorber TB has the same structure as the first adsorber TA and will not be described here; specifically, the workshop waste gas P1 is medium-high concentration waste gas from different industries, and the concentration range is generally 2-100 g / m 3 The workshop waste gas P1 first enters the temperature and humidity adjusting device 1, the temperature of the gas is adjusted to 30-40℃, and then enters the concentration buffer device 2, which is in the form of a cylinder or a flat panel and is internally provided with a microporous adsorbent with a high specific surface area, the specific surface area is ≥1200㎡ / g, the buffer device can balance the mixed gas of the workshop waste gas P1 discharged by the workshop and the desorption waste gas P3 generated in the displacement and desorption process to balance the oxygen, so as to balance the concentration of the mixed gas of the workshop waste gas P1 and the desorption waste gas P3 in a certain range, and ensure that the outlet concentration of the treated gas is relatively stable. The mixed gas is sent into the first adsorber TA and the second adsorber TB connected in parallel by the adsorption fan 3 for adsorption; it should be noted that according to the components, concentration and air volume of the waste gas, the adsorber can be provided as multiple adsorbers, and the working condition is continuous operation, and the number of adsorbers is at least two.

[0038] The first adsorber TA includes a first bed TA1 arranged near the exhaust gas inlet 103 thereof and a second bed TA2 arranged near the exhaust gas outlet 104 thereof; the first bed TA1 includes a first adsorption material, and the second bed TA2 includes a second adsorption material; the first adsorption material is a porous structure adsorption material with a first specific surface area; the second adsorption material is a microporous adsorption material with a second specific surface area, and the microporous adsorption material has a pore size ranging from 0.1 nm to 1 nm; the value of the first specific surface area is greater than the value of the second specific surface area; the thickness of the first bed accounts for 50% to 80% of the entire bed, and the thickness of the second bed accounts for 20% to 50% of the entire bed; similarly, the second adsorber TB includes a third bed TB1 arranged near the exhaust gas inlet thereof and a fourth bed TB2 arranged near the exhaust gas outlet thereof; the third bed TB1 includes a third adsorption material, and the fourth bed TB2 includes a fourth adsorption material; the third adsorption material is a porous structure adsorption material with a third specific surface area, and the fourth adsorption material is a microporous adsorption material with a fourth specific surface area; the value of the third specific surface area is greater than the value of the fourth specific surface area; the thickness of the third bed accounts for 50% to 80% of the entire bed, and the thickness of the fourth bed accounts for 20% to 50% of the entire bed. Specifically, two types of adsorption materials are arranged in each adsorber, the TA1 and the TB1 are high specific surface porous structure adsorption materials, arranged at the inlet side of the adsorber, and the bed thickness accounts for 50% to 80% of the entire bed, mainly to ensure the adsorption capacity of the adsorption process and ensure that the adsorption time meets the design requirements. The TA2 and the TB2 are microporous adsorption materials with uniform small specific surface area, arranged at the outlet side of the adsorber, and the bed thickness accounts for 20% to 50% of the entire bed, mainly to ensure the purification efficiency of the adsorption process and ensure that the outlet concentration meets the design emission standard. The design of the bed structure is more important to ensure that the residual high-concentration exhaust gas after desorption of the adsorber does not need to additionally increase the secondary adsorption bed or the molecular sieve rotating device, and the outlet concentration of the exhaust gas P1 after adsorption by the adsorber can reach 5 to 50 mg / m 3 The different heights of the adsorption beds TA1 and TA2 can be adjusted to meet the requirements of different outlet concentrations.

[0039] The desorption unit comprises an oxygen concentration detector, a full-effect heat exchanger 4 as a heat exchanger, a primary condenser 5 and a secondary condenser 6 as condensers, a layered tank 7, a desorption fan 8 and an electric heater 9, wherein the oxygen concentration detector comprises a first oxygen concentration detector C1 and a second oxygen concentration detector C2 arranged in series. The desorption unit has the same connection mode as the first adsorber TA and the second adsorber TB, and therefore only the connection mode of the desorption unit and the first adsorber TA is described subsequently. The first oxygen concentration detector C1 and the second oxygen concentration detector C2 are connected in sequence on the displacement gas outlet 102, and the nitrogen inlet 101 can be connected to nitrogen to purge the first bed TA1 and the second bed TA2 in the first adsorber TA to displace the gas containing oxygen and VOCs in the adsorber; the gas discharged from the displacement gas outlet 102 is also connected to the waste gas inlet 103 through a pipeline. The hot inlet 201 of the full-effect heat exchanger 4 is connected to the displacement gas outlet 102, and the first oxygen concentration detector C1 and the second oxygen concentration detector C2 arranged in series are located between the displacement gas outlet 102 and the hot inlet 201 of the full-effect heat exchanger 4. After the gas enters the full-effect heat exchanger 4 from the hot inlet 201, it enters the condenser after being condensed by the cold outlet 202 of the full-effect heat exchanger 4, and the condensed liquid enters the layered tank 7; the condensed gas is returned to the full-effect heat exchanger 4 from the cold inlet 203 of the full-effect heat exchanger 4, exchanges heat with the gas P4 entering the full-effect heat exchanger 4 from the hot inlet of the full-effect heat exchanger 4, and then is returned to the nitrogen inlet 101 from the hot outlet 204 of the full-effect heat exchanger 4, specifically, the air inlet side of the desorption fan 8 is connected to the hot outlet 204, the air outlet side of the desorption fan 8 is connected to the air inlet side of the heating device 9, and the air outlet side of the heating device 9 is connected to the nitrogen inlet 101.

[0040] The desorption process includes: when a certain adsorber in the plurality of adsorbers arranged in parallel is saturated, the system enters the regeneration mode, first, nitrogen gas P2 is introduced from the nitrogen gas inlet 101 to displace and purge the adsorber (TA / TB), the gas P3 containing oxygen and VOCs displaced is returned to the temperature and humidity adjusting device 1 and then enters the adsorber (TA / TB) from the waste gas inlet 103 for further treatment, the first oxygen concentration detector C1 and the second oxygen concentration detector C2 monitor the oxygen concentration in the system, when the oxygen concentration reaches the target safety value (too high oxygen concentration will have an explosion risk), the heating device 9 is started to heat, the gas temperature after heating is generally 180-200℃, the gas is driven by the desorption fan 8 to enter the adsorber (TA / TB) to regenerate the adsorption material, the gas P4 containing a large amount of VOCs and a small amount of moisture desorbed first passes through the total heat exchanger 4 for heat exchange, then enters the first condenser 5 for condensation, the first condenser 5 uses circulating water for condensation, the condensation temperature is 35-40℃, the gas p5 after first-stage condensation enters the second condenser 6 for second-stage condensation, the second-stage condensation temperature is 5-10℃, the condensate after condensation enters the stratification tank 7 for stratification and temporary storage, it should be noted that the first condenser 5 uses circulating water as the condensing medium, and / or the second condenser 6 uses chilled water as the condensing medium; the gas P6 after second-stage condensation enters the total heat exchanger 5 to exchange heat with the gas P4 discharged from the displacement gas outlet 102. The total heat exchanger 4 is a heat exchanger coated with adsorption material, which can be designed as a fixed bed and provided with a valve for switching, or designed as a rotary type for switching and heat transfer between high and low temperatures. Its typical features are: ① the heat exchanger is a honeycomb corrugated structure, the heat exchange efficiency can reach more than 80-90%, compared with the traditional plate heat exchanger and shell-and-tube heat exchanger, the resistance is smaller and the heat exchange efficiency is higher, which can save more than 40% of the desorption energy consumption. ② The low-temperature gas P6 after condensation has the characteristics of low temperature, generally 5-10℃, and high VOCs concentration, which is the saturated concentration at this temperature, generally the concentration is high, according to different components, the concentration range is 10-100 g / m 3 , and the VOCs have a high partial pressure, therefore, after passing through the total heat exchanger 4, a part of the high-concentration VOCs can be adsorbed by the total heat exchanger 4, and the concentration of the gas P7 after adsorption is reduced to 1-10 g / m 3, and the temperature is raised to 100-160°C, and after being heated again by the heater 9, it is returned to the adsorber TA / TB for further desorption. Due to the adsorption of the full-effect heat exchanger 4, the concentration of the gas P7 is reduced, and thus the desorption efficiency is improved and the desorption time is shortened. At the same time, the other high-temperature side gas P4 is the desorbed gas with a higher temperature, generally 150-200°C, which is discharged from the displacement gas outlet 102, and thus the desorbed gas can desorb the organic substances adsorbed by the full-effect heat exchanger 4, and thus the concentration of the gas P5 is further improved, and the desorption condensation efficiency is further improved. The full-effect heat exchanger 4 can adopt a rotary structure, and the low-temperature and high-temperature heat and substances can be exchanged by continuous rotation. Alternatively, a fixed bed structure can be used, and the low-temperature and high-temperature heat and substances can be exchanged by continuously switching the valves. After the full-effect heat exchanger 4 is used, the desorption time is shortened from the original 6h to 1-2h, and the desorption time is greatly shortened.

[0041] After the desorption is completed, the bed needs to be cooled, at which time the electric heater 9 stops heating, and the first condenser 5 and the second condenser 6 are used for circulating cooling. When the gas P4 is reduced to the target temperature, generally 40-60°C, the high-concentration VOCs remaining in the desorption circulating pipeline system and the adsorber are reduced to a reduced concentration, generally <1g / m 3 , and when the next stage is switched to the adsorption stage, the pipeline system does not need to be separately replaced to meet the standard requirements. Specific embodiments:

[0043] A coating production drying process exhaust gas, the exhaust gas volume is 50000Nm3 / h, the solvent components are ethyl acetate, butyl acetate and dimethylbenzene, the total concentration of the exhaust gas is 6000mg / m 3 , the exhaust gas emission temperature is 60°C, the relative humidity is 20%, and the exhaust gas emission concentration after treatment is required to be <30mg / m 3 . After the exhaust gas is cooled by the surface cooling, the gas temperature is reduced to 40°C, and then the exhaust gas enters the adsorption buffer device and enters the composite adsorber for adsorption. Four adsorption boxes are designed, of which three boxes are used for adsorption and one box is used for regeneration. Two kinds of adsorption materials are arranged in each adsorber, the bed thickness of the adsorption inlet side accounts for 80% of the total bed thickness, and the bed thickness of the adsorption outlet side accounts for 20% of the total adsorption bed thickness.

[0044] The four boxes are repeatedly circulated and switched to realize the exchange of adsorption and regeneration, and the exhaust concentration of the adsorbed VOCs is <20mg / m 3 . The adsorption outlet is provided with an online monitoring system for real-time detection of the chimney emission concentration. When the emission concentration reaches the design target or the adsorption time of the adsorber reaches the design time, a certain adsorber is switched to the regeneration stage.

[0045] Before desorption, the adsorber and piping system are first purged with nitrogen. When the oxygen concentration is <6%, nitrogen purging is stopped, and the desorption pipeline is heated to 1800–200℃. The desorption outlet temperature ranges from 40 to 180℃. The temperature after the first-stage condensation is 40℃, and the temperature after the second-stage condensation is 10℃. The concentration after condensation is 10 g / m³. 3 The final desorption equilibrium concentration was 10 g / m³. 3 .

[0046] During the desorption process, the desorption air volume is 10000 m³ / h. 3 The all-effect heat exchanger adopts a rotary structure with a rotation speed of 20 r / h. When the desorbed gas P4 is 180℃, after passing through the all-effect heat exchanger 4, the temperature of gas P5 drops to below 45℃, greatly reducing the design load on the condenser. Simultaneously, the temperature of gas P6 is 10℃, and after passing through the all-effect heat exchanger 4, the temperature of gas P7 rises to 145℃, also significantly reducing the load on the heater. The normal desorption time is 2 hours. During the desorption process, a dual-selection oxygen concentration detector is used to replenish nitrogen in real time according to changes in oxygen concentration, strictly controlling the oxygen content to <6% to ensure the safety and stability of the system.

[0047] After desorption, the system was cooled down to 40°C, and the equilibrium concentration in the pipeline after cooling was <1 g / m³. 3 After cooling, the process transitions to the adsorption stage for re-adsorption. The four chambers are repeatedly switched in a cycle to achieve the exchange between adsorption and regeneration.

[0048] In summary, the waste gas adsorption and recovery system provided by this invention creatively eliminates the secondary transfer tank and the molecular sieve rotor at the rear end of the desorption process. The adsorber is designed with two types of adsorption materials: a high specific surface area porous adsorption material at the inlet to ensure the adsorption capacity and ensure the adsorption time meets design requirements; and a low specific surface area uniform microporous adsorption material at the outlet to ensure the purification efficiency and ensure the outlet concentration meets design emission standards. The bed thickness of each adsorption material is adjustable, and the bed ratio of different materials can be adjusted according to the required outlet concentration. This invention has a simple process and can achieve an outlet concentration of 5–50 mg / m³ after adsorption. 3The application of full-effect heat exchanger is proposed, the high-efficiency adsorption material is coated in the heat exchanger, not only the high and low temperature heat exchange can be carried out, but also the material transmission can be carried out, the energy saving is realized, and the desorption efficiency is improved. The design of rotary full-effect heat exchanger is proposed, the high and low temperature heat exchange can be quickly realized, the high-density corrugated structure is adopted for the heat exchanger material, under the same pressure drop condition, the efficiency of traditional plate heat exchanger and shell-and-tube heat exchanger is 60-70%, and the efficiency of the heat exchanger can reach 80-90%, and the desorption energy consumption can be saved by more than 40%. In the desorption process, the oxygen content concentration detector is selected, the nitrogen is supplemented in real time according to the change of oxygen concentration, the oxygen content is strictly controlled, and the safety and stability of the system are ensured.

[0049] Please note that the technical features of the above embodiments can be combined arbitrarily, and in order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered that it is within the scope of the present application. The above embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as the limitation of the patent scope of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

[0050] The above is the preferred embodiment of the present application, it should be pointed out that, for ordinary skilled in the art, without departing from the principle of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. An exhaust gas adsorption recovery system characterized by comprising: The system comprises: a temperature and humidity adjusting device, a concentration buffering device and an adsorber connected in sequence; the adsorber comprises a first bed layer arranged near an exhaust gas inlet and a second bed layer arranged near an exhaust gas outlet; the first bed layer comprises a first adsorption material, and the second bed layer comprises a second adsorption material; the first adsorption material is a porous structure adsorption material with a first specific surface area; and / or, the second adsorption material is a microporous adsorption material with a second specific surface area; the value of the first specific surface area is greater than the value of the second specific surface area; the thickness of the first bed layer accounts for 50% to 80% of the entire bed layer, and the thickness of the second bed layer accounts for 20% to 50% of the entire bed layer.

2. The exhaust adsorption recovery system according to claim 1, characterized by A plurality of adsorbers are arranged in parallel.

3. The exhaust gas adsorption recovery system according to claim 1 or 2, characterized in that: a nitrogen gas inlet and a displacement gas outlet are arranged at the bottom and the top of the adsorber respectively, and the nitrogen gas inlet is provided with a heating device to heat the gas entering from the nitrogen gas inlet; the exhaust gas adsorption recovery system further comprises a desorption unit and an oxygen concentration detector arranged at the displacement gas outlet; the nitrogen gas inlet can be used to blow the first bed layer and the second bed layer to displace the gas containing oxygen and VOCs in the adsorber; the displacement gas outlet is connected to the exhaust gas inlet through a pipeline, and the desorption unit is connected to the displacement gas outlet.

4. The exhaust adsorption recovery system according to claim 3, characterized by The oxygen concentration detector comprises a first oxygen concentration detector and a second oxygen concentration detector arranged in sequence.

5. The exhaust gas adsorption recovery system according to claim 3, characterized in that: the desorption unit comprises a heat exchanger with an adsorption structure, a condenser and a layered tank; the hot inlet of the heat exchanger is connected to the displacement gas outlet, the gas entering from the hot inlet enters the heat exchanger, then enters the condenser from the cold outlet of the heat exchanger, and then the condensed liquid enters the layered tank; the condensed gas flows back to the heat exchanger from the cold inlet of the heat exchanger, exchanges heat with the gas entering the heat exchanger from the hot inlet of the heat exchanger, and then flows back to the nitrogen gas inlet from the hot outlet of the heat exchanger.

6. The exhaust adsorption recovery system according to claim 5, wherein The condenser comprises a first condenser and a second condenser arranged in sequence at the side of the cold outlet of the heat exchanger.

7. The exhaust gas adsorption recovery system according to claim 6, characterized in that: the first condenser uses circulating water as the condensing medium, and / or the second condenser uses chilled water as the condensing medium.

8. The exhaust adsorption recovery system according to claim 5, wherein The heat exchanger comprises a full-effect heat exchanger; the full-effect heat exchanger comprises a fixed bed heat exchanger or a rotary structure heat exchanger coated with an adsorption material.

9. The exhaust gas adsorption recovery system according to claim 5, characterized in that: the exhaust gas adsorption recovery system further comprises a desorption fan, the air inlet side of the desorption fan is connected to the hot outlet, the air outlet side of the desorption fan is connected to the air inlet side of the heating device, and the air outlet side of the heating device is connected to the nitrogen gas inlet.

10. The exhaust gas adsorption recovery system according to claim 1 or 2, characterized in that: The concentration buffering device comprises a cylindrical concentration buffering adsorption material or a flat concentration buffering adsorption material, and the specific surface of the concentration buffering adsorption material is greater than or equal to 1200 m2 / g.

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