Coating waste gas continuous treatment system

Abstract

The utility model provides a coating waste gas continuous treatment system. The treatment system comprises a biodegradation treatment system, a gas-water separator, a molecular sieve adsorption catalytic purification system and a fan, the biodegradation treatment system can enable VOCs waste gas entering the bottom of the biodegradation tower and running from bottom to top to fully contact and react with biological bacteria liquid sprayed from top to bottom in a vaporific manner to obtain purified gas in which most VOCs are degraded and removed; and the molecular sieve adsorption catalytic purification system can further purify the gas to reach the emission standard. The biodegradation treatment system comprises a biodegradation tower, aeration equipment, a biological bacterial liquid circulating system and a filter material layer; the gas-water separator comprises a gas inlet chamber, a condensate chamber, a gas-water separation chamber, filter cotton and filler filter stone; the molecular sieve adsorption catalytic purification system comprises a molecular sieve adsorption bed and a catalytic combustion bed. According to the treatment system, the VOCs in the coating waste gas can be continuously and efficiently degraded on line, the treatment reaches the standard, and the requirement of continuous production and online degradation of the VOCs of an enterprise can be met.

Description

Technical Field

[0001] The utility model belongs to the technical field of coating waste gas treatment, and relates to a coating waste gas continuous treatment system. Background Art

[0002] Painting is a high-energy consumption and high-pollution link in the automotive manufacturing industry. The waste gas generated during the spraying process is mainly volatile organic compounds (VOCs). They include benzene, toluene and xylene, which are harmful to the human body; and the VOCs contained in water-based paints are mainly hydrocarbons, halogenated hydrocarbons, oxygen hydrocarbons and nitrogen hydrocarbons. With the increasing improvement and strengthening of national environmental protection laws and regulations and energy-saving and emission reduction measures, choosing the appropriate waste gas treatment method to reduce VOCs emissions is what every spraying company and environmental protection equipment company should do.

[0003] The exhaust gas in the painting workshop mainly comes from the volatilized paint mist and solvent gas from spraying. The main sources of exhaust gas generated during the painting process include:

[0004] 1. The main harmful components in the exhaust gas emitted by the paint spraying room are the organic solvents volatilized during the painting process, mainly including aromatic hydrocarbons, alcohol ethers and ester organic solvents;

[0005] 2. Exhaust gas from the airing room. The topcoat needs to be leveled and aired after spraying and before drying. During the drying process, the organic solvent evaporates. The composition of the exhaust gas emitted from the airing room is similar to that of the exhaust gas from the spray paint room, but it does not contain paint mist. The total concentration of organic waste gas is higher than that of the exhaust gas from the spray paint room, and is usually mixed with the exhaust gas from the spray paint room for centralized treatment.

[0006] 3. Paint mixing room and wastewater treatment room also have similar organic waste gas emissions;

[0007] 4. Oil fume exhaust gas from the drying room. The composition of the drying exhaust gas is relatively complex, including organic solvents, resin curing, thermal decomposition products, etc. Both electrophoretic coatings and mid-coat and topcoat drying will emit oil fume exhaust gas, but the composition and concentration vary greatly.

[0008] At present, the main treatment methods for organic waste gas from painting are RCO catalytic combustion method and RTO regenerative combustion method.

[0009] 1. RCO catalytic combustion method, working principle: first, some dust particles in the organic waste gas are removed by a dry filter, and then the organic waste gas that meets the adsorption conditions is sent to the activated carbon adsorption box for adsorption purification, and the purified clean gas is discharged into the atmosphere through the main exhaust fan. The adsorption device is equipped with a set of spare adsorption boxes. When the activated carbon is saturated with adsorption, it switches to the catalytic combustion desorption state through the control valve. The desorption regeneration system adopts online desorption regeneration or offline desorption regeneration, that is, the adsorption process is a continuous treatment process. When the spare adsorption device is put into use, the saturated adsorption box performs desorption work. After desorption, the activated carbon box is ready for the next cycle. The concentration of the desorbed organic matter is dozens of times higher than the original and is sent to the catalytic combustion chamber for catalytic combustion reaction. The reaction is carried out at 200-350°C on the catalyst surface to convert it into harmless water and carbon dioxide. Its disadvantages are: the waste gas treatment capacity is limited, and it is only suitable for the treatment of organic waste gas containing low-boiling point organic components and low ash content; when the waste gas contains sticky substances such as oil smoke, the activated carbon is not easy to desorb and the service life is shortened; the core unit catalyst (precious metal) is easily poisoned and fails; the replaced activated carbon is hazardous waste, causing secondary pollution.

[0010] 2. RTO regenerative combustion method has the following disadvantages: high one-time investment cost; high processing temperature (800-1100℃), high energy consumption, large amount of natural gas consumption, not suitable for processing high-concentration organic waste gas, many moving parts, frequent maintenance is required, and high equipment operation and maintenance cost; due to the high working temperature, high requirements for insulation and other hardware are also required.

[0011] In order to overcome the defects of RTO and RCO in the treatment of VOCs waste gas, such as high energy consumption and easy poisoning of catalysts, low-energy biofilm method, photolysis method, ozone decomposition method, biodegradation method, etc. have been developed. Biological degradation has the characteristics of low energy consumption, low cost, safety and environmental protection, but some current biological methods for degrading VOCs cannot meet the needs of coating waste gas treatment. Basically, they are auxiliary with organisms, or waste gas needs to be collected and then processed, which cannot meet the needs of enterprises for continuous production and online degradation of VOCs. For example, the device in patent 202320759284.7 can only handle very small air volumes. The method and device for treating difficult-to-degrade organic waste gas by combining low-temperature plasma with biology first need to collect gas and then degrade it; secondly, plasma equipment requires high-voltage power supply, which is dangerous; finally, the main function of the biological trickling filter, filter tower or washing tower used in this technology is to remove dust and deodorize, and cannot play a degradation role. The biological bacteria used in some other biological methods cannot efficiently degrade waste gas. Utility Model Content

[0012] The purpose of the utility model is to solve the problems existing in the background technology, overcome the shortcomings of the existing technology, and provide a continuous treatment system for painting waste gas which can continuously produce online and efficiently degrade VOCs in painting waste gas, meet the emission standards after treatment, and meet the needs of enterprises for continuous production and online degradation of VOCs.

[0013] The technical solution of the utility model is as follows:

[0014] The utility model discloses a continuous treatment system for coating waste gas, comprising a biodegradation treatment system, a gas-water separator, a molecular sieve adsorption catalytic purification system and a fan connected in sequence; the biodegradation treatment system can make the VOCs waste gas entering the bottom of the biodegradation tower and running from bottom to top fully contact and react with the biological bacteria liquid sprayed from top to bottom in a mist form, so as to obtain a first purified gas for degrading and removing most of the VOCs; the gas-water separator can remove moisture and impurities from the first purified gas, so as to obtain a second purified gas; the molecular sieve adsorption catalytic purification system can further adsorb and burn the second purified gas to purify it to meet the emission standards.

[0015] The biodegradation treatment system includes a biodegradation tower, a biological bacteria liquid circulation system, an aeration device and a filter material layer. The biodegradation tower is the main tower of the biodegradation treatment system, which is a closed horizontal tower with biological bacteria liquid at the bottom of the tower; the biological bacteria liquid circulation system includes a circulating water pump and a vertical spray pipe and a spray head connected to its outlet; the circulating water pump is arranged at the bottom of the biodegradation tower, and the spray head is arranged at the top of the biodegradation tower; the aeration device is an oxygen supply fan, which is located outside the biodegradation tower, and its outlet pipe is connected to the bottom of the tower to supply oxygen for the biological bacteria; the filter material layer is filled with porous filter material; the waste gas inlet and waste gas outlet are arranged on both sides of the biodegradation tower, the waste gas inlet is located at the top of one side of the tower, and the waste gas outlet is located at the top of the other side of the tower. A vertical air inlet channel is arranged near the exhaust gas inlet in the tower, and the exhaust gas enters the bottom of the tower through the air inlet channel; the rest of the middle and upper space in the tower is divided into multiple reaction chambers by multiple filter material layers arranged in parallel at vertical intervals, and each reaction chamber is equipped with a set of biological bacterial liquid circulation system including a circulating water pump and a vertical spray pipe and a spray head connected to its outlet, and the spray heads are symmetrically arranged at different heights on the vertical spray pipe; in each reaction chamber, the biological bacterial liquid at the bottom of the biodegradation tower passes through the circulating water pump and the vertical spray pipe connected to its outlet to reach the spray head at the top, and is atomized and sprayed from top to bottom, fully contacting and reacting with the exhaust gas running from bottom to top entering the bottom of the tower, and most of the VOCs in the exhaust gas are degraded by biological bacteria; then the exhaust gas absorbs water through the porous filter material of the filter material layer, comes out from the exhaust gas outlet, and enters the gas-water separator for gas-water separation.

[0016] Furthermore, the biodegradation treatment system also includes a demister; a wave plate demister is provided at the waste gas outlet of the biodegradation tower. The biological bacteria liquid at the bottom of the biodegradation tower is atomized by the circulating water pump and pipeline to the top of the spray head, and then contacts and reacts with the waste gas entering the tower, and most of the VOCs in the waste gas are degraded by the biological bacteria; then the waste gas absorbs water through the filter material layer (porous filter material), and then passes through the demister to demister, and then enters the gas-water separator for gas-water separation.

[0017] Furthermore, the biodegradation treatment system also includes a pH value control module, a temperature control module and a dissolved oxygen value control module, which automatically controls the pH value, temperature and dissolved oxygen value of the biodegradation tower through a PLC controller; a pH value sensor, a temperature sensor and a dissolved oxygen value sensor are provided in the biodegradation tower; the signal input end of the temperature controller is connected to the temperature sensor, and the signal output end is connected to the electric heater of the biodegradation tower; the signal input end of the pH value controller is connected to the pH value sensor, and the signal output end is connected to the acid and alkali tank; the signal input end of the dissolved oxygen controller is connected to the dissolved oxygen value sensor, and the signal output end is connected to the oxygen supply fan.

[0018] As a preferred embodiment of the present invention, the bacterial species in the biological bacterial liquid are one or both of Beyerlinckia LM-W and Brevmonas LM-R, which can capture, disperse and degrade the waste gas.

[0019] The biodegradation treatment system can be a plurality of biodegradation towers connected in series.

[0020] The gas-water separator includes an air inlet chamber, a condensation chamber and an air-water separation chamber; the air inlet chamber is separated from the air-water separation chamber; the condensation chamber is located below the air inlet chamber and the air-water separation chamber; the air inlet is located at the top of the air inlet chamber of the gas-water separator, and the air outlet is located at the top of the gas-water separation chamber; the upper part of the gas-water separation chamber is provided with filter cotton (PP wire mesh demister), and the lower part is provided with filler filter stone (fiber stone filter); after the gas enters the gas-water separator, it is filtered by the filter cotton (PP wire mesh demister) and the filler filter stone (fiber stone filter) and the moisture in the gas is removed. The function of the gas-water separator is to process the gas containing a small amount of condensate, realize condensate recovery or gas phase purification. The gas-water separator allows the gas phase and liquid phase mixed with each other to polymerize into strands, the droplets collide and coalesce, and the gas rises after the droplets are removed, thereby achieving the purpose of separation. Considering factors such as system resistance, this system adopts a wave plate demister + fiber stone filter + PP wire mesh demister to achieve the effect of gas-water separation.

[0021] Furthermore, a biological bacteria circulating water tank is provided between the gas-water separator and the biodegradation tower; the water outlet at the bottom of the gas-water separator is connected to the inlet of the biological bacteria circulating water tank, and the outlet of the biological bacteria circulating water tank is connected to the biodegradation tower. The water collected after the droplets of gas-water separation in the gas-water separator coalesce, which also contains a small amount of biological bacteria, can be returned to the biodegradation tower for recycling, or returned to the biological bacteria circulating water tank for the preparation of biological bacteria liquid; the biological bacteria circulating water tank is connected to the biodegradation tower.

[0022] The molecular sieve adsorption catalytic purification system comprises a molecular sieve adsorption bed and a catalytic combustion bed (i.e., a catalytic oxidation furnace or a catalytic combustion furnace); the molecular sieve adsorption beds are multiple and connected in parallel; the air inlet of the molecular sieve adsorption catalytic purification system is respectively connected with the inlet of each molecular sieve adsorption bed; the air outlet of the molecular sieve adsorption catalytic purification system is respectively connected with the outlet of each molecular sieve adsorption bed; an adsorption air valve is provided at the inlet of each molecular sieve adsorption bed, and a desorption air valve is provided at the outlet; the inlet of the catalytic combustion bed is respectively connected with the outlet of each molecular sieve adsorption bed; the outlet of the catalytic combustion bed is connected with the air outlet of the molecular sieve adsorption catalytic purification system; the catalytic combustion bed is provided with an electric heater and a catalyst; the outlet of the catalytic combustion bed is connected with the air outlet of the molecular sieve adsorption catalytic purification system; the air outlet of the molecular sieve adsorption catalytic purification system is connected with the inlet of the fan, and the outlet of the fan is connected with the chimney; the exhaust gas dehumidified by the gas-water separator is discharged in compliance with the emission standards after molecular sieve adsorption and catalytic combustion.

[0023] Furthermore, the molecular sieve adsorption catalytic purification system also includes a preheater and a heat exchanger; the desorption air valve, preheater, and catalytic combustion bed are connected in sequence to form a desorption-catalytic combustion system; the catalytic combustion bed outlet is connected to the fan inlet through the heat exchanger, and the fan outlet is connected to the chimney.

[0024] After the waste gas dehumidified by the gas-water separator enters the molecular sieve adsorption catalytic purification system, it first enters the molecular sieve adsorption bed for adsorption. After the saturated molecular sieve is desorbed by hot air and catalytically burned, the organic waste gas adsorbed on it is burned to generate CO2 and H2O, which are purified and discharged into the atmosphere in compliance with the standards. The molecular sieve regains its adsorption capacity and is recycled.

[0025] The molecular sieve adsorption catalytic purification system adopts a molecular sieve adsorption + hot air desorption - catalytic combustion process, and the main equipment of the system is a molecular sieve adsorption bed and a catalytic combustion bed.

[0026] (I) Molecular sieve adsorption, molecular sieve adsorption bed

[0027] (1) Principle of adsorption of zeolite molecular sieve: The adsorption of zeolite molecular sieve is a physical change process. The main reason for adsorption is a "surface force" generated by the molecular gravity acting on the solid surface. When the fluid flows through, some molecules in the fluid collide with the adsorbent surface due to irregular motion, resulting in molecular concentration on the surface, which reduces the number of such molecules in the fluid and achieves the purpose of separation and removal. Since adsorption does not cause chemical changes, as long as the molecules concentrated on the surface are driven away, the zeolite molecular sieve will have adsorption capacity again. This process is the reverse process of adsorption, called analysis or regeneration. Since the pore size of zeolite molecular sieve is uniform, only when the molecular dynamic diameter is smaller than the pore size of zeolite molecular sieve can it easily enter the crystal cavity and be adsorbed. Therefore, zeolite molecular sieve is like a sieve for gas and liquid molecules, and whether it is adsorbed depends on the size of the molecule. Since the crystal cavity of zeolite molecular sieve also has strong polarity, it can have a strong effect on the zeolite molecular sieve surface with molecules containing polar groups, or induce polarization of polarizable molecules to produce strong adsorption. The characteristic that polar or easily polarizable molecules are easily adsorbed by polar zeolite molecular sieves reflects another adsorption selectivity of zeolite molecular sieves.

[0028] (2) Characteristics of zeolite molecular sieve: Zeolite molecular sieve adsorption uses physical adsorption to adsorb VOCs into the molecular sieve, and then increases the temperature to allow the VOCs to escape, completing the entire process of adsorption and desorption. The adsorption of zeolite molecular sieve is mainly selective adsorption, which uses the molecular shape and size of the adsorbate, as well as the molecular polarity and unsaturation to perform selective adsorption.

[0029] (3) Characteristics of zeolite molecular sieves: There are many types of zeolite molecular sieves. They have the characteristics of screening molecules by forming a pore and cavity system of molecular size (usually 0.3nm to 2.0nm) through the connection of silicon-oxygen tetrahedrons or aluminum-oxygen tetrahedrons through oxygen bridge bonds. Oxygen rings are connected through oxygen bridges to form a polyhedron with a three-dimensional space. The polyhedron has a hollow cage, and the cage structure is the skeleton structure of the molecular sieve. Cages of different structures are then connected to each other through oxygen bridges to form molecular sieves of various structures.

[0030] (4) Adjusting adsorption capacity: The performance of molecular sieves can be optimized by changing the ratio of silica and alumina, and the adsorption capacity of molecular sieves can be adjusted. High-silicon zeolite molecular sieves significantly change their hydrophobicity and also change their temperature resistance. The adaptability to VOCs working conditions has been expanded. The impact of high humidity environment and ambient temperature changes on the adsorption concentration effect is reduced. There are ions (sodium, potassium, calcium, etc.) in the structure of zeolite crystals. Through the exchange of cations, the pore size can be changed, thereby achieving more efficient adsorption of target pollutants.

[0031] (5) Safety: Zeolite material itself is a non-combustible substance, which provides greater assurance of safety in application.

[0032] (II) Catalytic purification and catalytic combustion bed

[0033] After the adsorption saturated molecular sieve is desorbed by hot air and catalytically burned, the VOCs in the organic waste gas adsorbed on it are burned to generate CO2 and H2O. The organic waste gas is purified and meets the standards and can be discharged into the atmosphere; the molecular sieve regains its adsorption capacity and is recycled.

[0034] Molecular sieve adsorption catalytic purification is a typical gas-solid phase catalytic reaction, and its essence is the deep oxidation with the participation of active oxygen. In the catalytic purification process, the role of the catalyst is to reduce the activation energy. At the same time, the catalyst surface has an adsorption effect, which makes the reactant molecules enriched on the surface, increases the reaction rate, and accelerates the reaction; with the help of the catalyst, the organic waste gas can be flamelessly burned at a lower ignition temperature, and oxidized and decomposed into CO2 and H2O, while releasing a large amount of heat energy, thereby achieving the method of removing harmful substances in the waste gas.

[0035] In the process of catalytic purification of exhaust gas, the exhaust gas is sent to the heat exchanger through the pipeline by the fan, and the exhaust gas is heated to the starting temperature required for catalytic combustion. The preheated exhaust gas passes through the catalyst layer to burn. Due to the effect of the catalyst, the starting temperature of the exhaust gas combustion in the catalytic combustion method is about 250-300℃, which is much lower than the combustion temperature of the direct combustion method of 650-800℃. The high-temperature gas enters the heat exchanger again, is cooled by heat exchange, and finally discharged into the atmosphere at a lower temperature through the fan.

[0036] Before the organic waste gas is introduced into the catalytic combustion device (catalytic combustion bed), the waste gas is first preheated by a preheater, and then the waste gas is heated by an electric heater in the catalytic combustion bed (i.e., catalytic oxidation furnace) to raise the waste gas temperature to about 250-300°C. Under the action of the catalyst, the thermal reaction generates harmless H2O and CO2. At this time, no electric heating is required, and the high-concentration organic waste gas is treated by self-balance. A large amount of heat is released after combustion, and a heat exchanger can be used to recycle the high-temperature exhaust gas to reduce preheating energy consumption. The above process can be fully automatically operated through the PLC system control cabinet.

[0037] Due to the large air volume of 200,000 m3 / h, this solution uses two molecular sieve exhaust gas purification systems, with a single processing capacity of 100,000 m3 / h; a single set of 5 uses and one desorption process, a single set of filtration area of ​​28.8m2, filtration adsorption wind speed: 0.97m / s; the molecular sieve filling thickness is 0.6m, effective adsorption time: 0.62s, two sets of purification systems are arranged in parallel, and the two systems run at the same time, so as to meet the processing capacity of 200,000 m3 per hour; that is, the system is equipped with six adsorption boxes, five for adsorption and one for desorption or standby. During the painting work, adsorption boxes A, B / C / D / E are turned on and run (adsorption box F is desorbing or on standby). When adsorption box A reaches saturation, the adsorption-desorption program is automatically switched: adsorption box A stops air intake and enters the desorption program, while adsorption box B starts air intake and enters the adsorption program.

[0038] Under the operation of the desorption-catalytic combustion system, the molecular sieve in the adsorption box A desorbs organic gas from the molecular sieve, is burned and decomposed by the catalytic combustion bed, and finally regenerates the molecular sieve to regain its adsorption capacity. The working process of the desorption-catalytic combustion system is: open the desorption air valve, the desorbed gas enters the catalytic combustion bed for catalytic oxidation combustion, the gas after combustion has been purified to meet the standards, and finally enters the chimney through the fan to be discharged into the atmosphere.

[0039] Automatic adsorption-desorption is controlled by a PLC controller. The signal input end of the PLC controller is connected to a pressure difference sensor arranged on the exhaust gas pipeline, and the signal output end is connected to an adsorption air valve and a desorption air valve respectively.

[0040] The working principle of molecular sieve adsorption and desorption-catalytic combustion is to combine molecular sieve adsorption and catalytic combustion. The function of molecular sieve adsorption and desorption is to concentrate low-concentration exhaust gas into high-concentration exhaust gas. If the low-concentration exhaust gas with large air volume is directly catalytically combusted, the energy consumption (power consumption) will be very large and the efficiency will be too low. Therefore, the exhaust gas is first adsorbed by molecular sieve. When the molecular sieve reaches a certain saturation, high-temperature desorption is performed. The desorbed exhaust gas is then sent to the catalytic combustion furnace for high-temperature oxidation and decomposition. At the same time, the high temperature generated cannot be wasted. The heat exchanger can be used for heat exchange and heat recovery. The recovered heat is reused and sent to the molecular sieve module for desorption again, so as to cycle. The high-temperature air of the catalytic combustion furnace is used to heat the molecular sieve. The high-concentration organic matter adsorbed in the pore size of the molecular sieve reaches the boiling point and will be separated from the molecular sieve. The desorbed high-concentration exhaust gas is sent to the catalytic combustion furnace for high-temperature oxidation. Under the ignition temperature condition of 250℃~300℃, high-concentration exhaust gas is converted into carbon dioxide and water through oxidation reaction through the action of catalyst. This is a high-temperature chemical reaction rather than open flame combustion. The exhaust gas after oxidation and decomposition meets the emission standards.

[0041] The specific working process of the molecular sieve adsorption catalytic purification system is as follows: after the exhaust gas dehumidified by the gas-water separator enters the molecular sieve adsorption catalytic purification system, it first enters the molecular sieve adsorption bed for adsorption. At this time, a small amount of VOCs (content of about 8%) in the exhaust gas is adsorbed on the molecular sieve, and the remaining 92% of the clean gas that meets the standard is sent to the chimney through the suction fan to be discharged into the atmosphere. Then, the adsorption saturated molecular sieve adsorption bed is desorbed by hot air (the hot air is the high-temperature air after combustion from the catalytic combustion bed), and the VOCs (concentrated VOCs) adsorbed on the molecular sieve are desorbed from the molecular sieve, and together with the hot air, they form high-concentration organic waste gas, and enter the catalytic combustion bed (catalytic oxidation furnace) through the desorption air valve for catalytic oxidation combustion. After the VOCs in the exhaust gas are burned, CO2 and H2O are generated (that is, the purification meets the standard). The exhaust gas that meets the standard is finally sent to the chimney through the suction fan to be discharged into the atmosphere. The desorbed exhaust gas is first preheated in a preheater, and then heated to 250-300°C by an electric heater in a catalytic combustion bed. It is burned under the action of a catalyst and then discharged into the atmosphere.

[0042] The beneficial effects of the utility model are as follows:

[0043] The utility model provides a continuous treatment system for coating waste gas, which can effectively treat VOCs in coating waste gas, the biological bacterial liquid can be recycled, and the treated waste gas can meet the emission standards, solving the problems of difficult gas-liquid mixing and difficult waste gas capture and degradation. The utility model has the following characteristics: high performance, high reliability, easy operation, low risk, no use of natural gas throughout the process, carbon emission reduction, controllable normal temperature, cost reduction and efficiency improvement, green and environmental protection; can efficiently degrade VOCs in coating waste gas, can meet emission standards after treatment, can continuously capture and degrade coating waste gas online, and meet the requirements of continuous production of enterprises; low energy consumption, low cost, safety and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] By referring to the following description of the drawings, and with a more comprehensive understanding of the present invention, other purposes and results of the present invention will become more clear and easy to understand. In the drawings:

[0045] Figure 1 It is a schematic diagram of the overall structure of the continuous treatment system for painting waste gas of the present utility model.

[0046] Figure 2 This is the process flow chart of the molecular sieve adsorption catalytic purification system.

[0047] The accompanying drawings are marked as follows: 1. Biodegradation treatment system, 2. Circulating water pump, 3. Sprinkler head, 4. Filter material layer, 5. Defogger, 6. Gas-water separator, 7. Fiber stone filter, 8. PP wire mesh demister, 9. Molecular sieve adsorption catalytic purification system, 10. Molecular sieve adsorption bed, 11. Desorption air valve, 12. Adsorption air valve, 13. Catalytic combustion bed, 15. Fan, 16. Aeration equipment, 17. Waste gas inlet, 18. Waste gas outlet, 19. Biological bacteria circulating water tank, 20. Biodegradation tower, 21. Flame arrester, 22. Air filter, 23. Draft fan, 24. Hot air inlet, 25. Purified air outlet, 26. Condensate chamber, 27. Air intake chamber, 28. Gas-water separation chamber. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution and key points of the present invention, the present invention is described in detail below with reference to the accompanying drawings and embodiments, but is not intended to limit the protection scope of the present invention.

[0049] In the description of the present application, it should be noted that the terms "inside", "outside", "upper", "lower", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or the directions or positional relationships in which the product of the application is usually placed when in use. These directions are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0050] In the description of this application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediary medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] Example 1

[0052] See also Figure 1As shown: This embodiment is a continuous treatment system for coating waste gas, comprising a biodegradation treatment system 1, a gas-water separation system (gas-water separator 6), a molecular sieve adsorption catalytic purification system 9 and a fan 15 connected in sequence. The biodegradation treatment system 1 can make the VOCs waste gas entering the bottom of the biodegradation tower from bottom to top fully contact and react with the biological bacterial liquid sprayed from top to bottom in a mist form, so as to obtain a first purified gas that degrades and removes most of the VOCs; the gas-water separator 6 can remove moisture and impurities from the first purified gas to obtain a second purified gas; the molecular sieve adsorption catalytic purification system 9 can further adsorb and burn the second purified gas to purify it to meet the emission standards.

[0053] like Figure 1As shown, the biodegradation treatment system 1 includes a biodegradation tower 20 (bioreactor tower), a filter material layer 4, a spray head 3, a circulating water pump 2, an aeration device 16 (oxygen supply fan), and a demister 5. The biodegradation tower 20 is the main tower of the biodegradation treatment system. It is a closed horizontal tower with biological bacterial liquid at the bottom of the tower; the circulating water pump 2 is arranged at the bottom of the biodegradation tower, and the spray head 3 is arranged at the top of the biodegradation tower. The circulating water pump 2 and the vertical spray pipe connected to its outlet and the spray head 3 constitute a biological bacterial liquid circulation system. The aeration device 16 is an oxygen supply fan, which is located outside the biodegradation tower, and its outlet pipe is connected to the bottom of the tower to provide oxygen for the biological bacterial liquid at the bottom of the tower. The filler of the filter layer 4 is a porous filter material, which has good corrosion resistance to acids and alkalis, and has the characteristics of large specific surface area, low density, low thermal conductivity, low relative density, high porosity, high adsorption rate, etc. It has the characteristics of catalyst (including carrier), adsorbent (decolorization), heat preservation, insulation, etc., and has good effects on water absorption and waste gas treatment. A waste gas inlet 17 and a waste gas outlet 18 are arranged on both sides of the biodegradation tower 20. The waste gas inlet 17 is located at the top of one side of the tower, and the waste gas outlet 18 is located at the top of the other side of the tower. A vertical air inlet channel is arranged near the waste gas inlet 17 in the tower, and the waste gas enters the bottom of the tower through the air inlet channel. The remaining middle and upper space in the tower is divided into multiple reaction chambers by multiple filter material layers 4 arranged in parallel at vertical intervals. Each reaction chamber is equipped with a set of biological bacterial liquid circulation system (including a circulating water pump 2 and a vertical spray pipe and a spray head 3 connected to its outlet), and the spray heads 3 are symmetrically arranged at different heights on the vertical spray pipe. A corrugated plate demister 5 is provided at the waste gas outlet 18 of the biodegradation tower 20. In each reaction chamber, the biological bacteria liquid at the bottom of the biodegradation tower 20 reaches the spray head 3 at the top through the vertical spray pipe connected to the outlet of the circulating water pump 2, and is sprayed from top to bottom after being atomized, and fully contacts and reacts with the waste gas entering the bottom of the tower and running from bottom to top (the painting waste gas enters the bioreaction tower 20 from the waste gas inlet 17 on the left side through the air duct of the original blower in the painting workshop and runs from bottom to top, and fully contacts and reacts with the biological bacteria liquid sprayed from top to bottom by the spray head 3 through the circulating pump 2 in the tower. The bioreaction tower 20 is designed as such a horizontal tower, and the contact reaction is more complete and the degradation efficiency is higher). Most of the VOCs in the waste gas are degraded by the biological bacteria; thereafter, the waste gas absorbs water through the filter material layer 4, and then passes through the demister 5 for defogger, and leaves the biological adsorption and degradation system 1 from the waste gas outlet 18 and the air outlet pipe on the top right, and enters the gas-water separator 6.

[0054] The bacterial species in the biological bacterial liquid are one or both of Beyerlinckia LM-W and Brevimonas LM-R, which can capture, disperse and degrade the waste gas.

[0055] The biodegradation treatment system 1 is provided with a pH value control module, a temperature control module and a dissolved oxygen value control module, and the pH value, temperature and dissolved oxygen value of the biodegradation tower are automatically controlled by a PLC controller; a pH value sensor, a temperature sensor and a dissolved oxygen value sensor are provided in the biodegradation tower 20; the signal input end of the temperature controller is connected to the temperature sensor, and the signal output end is connected to the electric heater of the biodegradation tower; the signal input end of the pH value controller is connected to the pH value sensor, and the signal output end is connected to the acid-base tank; the signal input end of the dissolved oxygen controller is connected to the dissolved oxygen value sensor, and the signal output end is connected to the oxygen supply fan. The temperature, pH value and dissolved oxygen of the biodegradation tower are automatically controlled by the PLC controller.

[0056] like Figure 1 As shown, the gas-water separator 6 includes an air inlet, an air inlet chamber 27, a condensation chamber 26, an air-water separation chamber 28 and an air outlet which are connected in sequence; the air inlet chamber 27 is separated from the air-water separation chamber 28; the condensation chamber 26 is located below the air inlet chamber 27 and the air-water separation chamber 28; the air inlet is located at the top of the air inlet chamber 27 on the left side of the gas-water separator 6, and the air outlet is located at the top of the air-water separation chamber 28 on the right side. The air-water separation chamber 28 includes filter cotton (PP wire mesh demister 8) and filler (fiber stone filter 7); the upper part of the air-water separation chamber 28 is provided with a multi-layer PP wire mesh demister 8, and the lower part is provided with a fiber stone filter 7; the gas enters the air inlet chamber 27 of the gas-water separator 6 from the top on the left side, and then enters the air-water separation chamber 28 from the bottom to the top from the bottom, first passes through the fiber stone filter 7 for the first water removal, and then passes through the PP wire mesh demister 8 for the second water removal, and the water after the air-water separation, that is, the condensate, falls into the condensation chamber 26. After the gas enters the gas-water separator, it is filtered through two filters, namely, the filler filter stone (fiber stone filter) and the filter cotton (PP wire mesh demister), and the moisture in the gas is removed. The function of the gas-water separator is to process the gas containing a small amount of condensate to achieve condensate recovery or gas phase purification. The gas-water separator allows the mixed gas and liquid phases to aggregate into strands, the droplets collide and coalesce, and the gas rises after the droplets are removed, thereby achieving the purpose of separation. Considering factors such as system resistance, this system uses a wave plate demister + fiber stone filter + PP wire mesh demister to achieve the effect of gas-water separation.

[0057] A biological bacteria circulating water tank 19 is provided between the gas-water separator 6 and the biodegradation tower 20; the water outlet at the bottom of the gas-water separator 6 is connected to the inlet of the biological bacteria circulating water tank 19, and the outlet of the biological bacteria circulating water tank 19 is connected to the biodegradation tower 20. The water collected after the droplets of gas-water separation in the gas-water separator 6 coalesce, which also contains a small amount of biological bacteria, can be returned to the biodegradation tower for return water utilization, and can be returned to the biological bacteria circulating water tank for the preparation of biological bacteria liquid.

[0058] like Figure 2As shown, the molecular sieve adsorption catalytic purification system 9 includes an air inlet, a molecular sieve adsorption bed 10, a catalytic combustion bed 13 (catalytic oxidation furnace) and an air outlet connected in sequence, and also includes a preheater and a heat exchanger; the molecular sieve adsorption beds 10 are multiple and connected in parallel; the air inlet of the molecular sieve adsorption catalytic purification system 9 is respectively connected to the inlet of each molecular sieve adsorption bed 10; the air outlet of the molecular sieve adsorption catalytic purification system 9 is respectively connected to the outlet of each molecular sieve adsorption bed 10; an adsorption air valve 12 is provided at the bottom inlet of each molecular sieve adsorption bed 10, and a desorption air valve 11 is provided at the bottom outlet; the inlet of the catalytic combustion bed 13 is respectively connected to the outlet of each molecular sieve adsorption bed 10; the outlet of the catalytic combustion bed 13 is connected to the air outlet of the molecular sieve adsorption catalytic purification system 9; the catalytic combustion bed 13 is provided with an electric heater and a catalyst; the desorption air valve 11, the preheater, and the catalytic combustion bed 13 are connected in sequence to form a desorption-catalytic combustion system; the outlet of the catalytic combustion bed 13 is connected to the fan 15 through a heat exchanger, and the fan 15 is connected to the chimney. An induced draft fan 23 is provided on the outlet pipe of the catalytic combustion bed 13, and the outlet of the induced draft fan 23 is respectively connected to the hot air inlet 24 on the top of each molecular sieve adsorption bed 10; the purified air outlet 25 on the top of each molecular sieve adsorption bed 10 is connected to the fan 15. A flame arrester 21 is respectively provided on the inlet and outlet pipes of the catalytic combustion bed 13. An air filter 22 is provided at the fresh air inlet of the molecular sieve adsorption catalytic purification system 9. A differential pressure sensor is provided on the exhaust gas pipeline. Automatic adsorption-desorption is controlled by a PLC controller. The signal input end of the PLC controller is connected to the differential pressure sensor provided on the exhaust gas pipeline, and the signal output end is respectively connected to the adsorption air valve 12 and the desorption air valve 11.

[0059] The working process of the molecular sieve adsorption catalytic purification system 9 is as follows: the coating waste gas after dehumidification by the gas-water separator enters the molecular sieve adsorption catalytic purification system 9, and first enters the molecular sieve adsorption bed 10 for adsorption through the adsorption air valve 12. At this time, a small amount of VOCs (content of about 8%) in the waste gas is adsorbed on the molecular sieve, and the remaining 92% of the clean gas that meets the standard is sent to the chimney through the fan 15 to be discharged into the atmosphere. Then, the adsorption saturated molecular sieve adsorption bed is desorbed by hot air (the hot air is the high-temperature air from the outlet of the catalytic combustion bed), and the VOCs (concentrated VOCs) adsorbed on the molecular sieve are desorbed from the molecular sieve, and together with the hot air, a high-concentration organic waste gas is formed, and it enters the catalytic oxidation furnace 13 (i.e., the catalytic combustion bed) through the desorption air valve 11 for catalytic oxidation combustion. After the VOCs in the waste gas are burned, CO2 and H2O are generated (i.e., the purification meets the standard). The waste gas that meets the standard is finally sent to the chimney through the fan 15 (suction fan) to be discharged into the atmosphere.

[0060] In the project of the continuous treatment system of coating waste gas in this embodiment, the biodegradation treatment system 1 is provided with a spray layer, a demisting layer, a stainless steel water spray system, a set of temperature sensing systems, a set of pressure difference sensing systems, a set of wind speed sensing systems, a set of air inlet particle concentration meters, a set of air inlet temperature sensing systems, a set of circulating water tank temperature sensing systems, a set of biological bacteria automatic dosing systems, a set of circulating water pipeline circulating water monitoring systems and a set of automatic water replenishment systems. The gas-water separator equipment structure is a multi-layer composite structure; the gas-water separation system is provided with a set of pressure difference transmission system, a set of temperature sensing system and a set of particle concentration meters, and the filter layer has multiple channels. There are two sets of molecular sieve adsorption catalytic purification systems, each set has 5 molecular sieve adsorption boxes (molecular sieve adsorption beds) and 1 catalytic combustion furnace (catalytic combustion bed), 1 set of pressure difference sensing systems, and 14 sets of temperature sensing systems. Each set of molecular sieve adsorption catalytic purification system 9 is provided with two sets of emergency explosion unloading devices and two sets of system fire arresting devices (flame arresters 21), and is also provided with an emergency fire sprinkler system.

[0061] Example 2

[0062] The continuous treatment system for coating waste gas in the present embodiment is basically the same as the continuous treatment system for coating waste gas described in Example 1, except that: there are two sets of molecular sieve adsorption catalytic purification systems, each set is equipped with three molecular sieve adsorption boxes (molecular sieve adsorption beds), and a total of six molecular sieve adsorption boxes are equipped, five for adsorption and one for desorption or standby.

[0063] A method for treating painting waste gas using the painting waste gas continuous treatment system described in Example 2 is as follows:

[0064] The coating waste gas generated by the coating workshop (VOCs concentration is 200mg / m 3 —1800 mg / m 3 ) enters the biodegradation treatment system through the exhaust main pipe, and the large air volume and low concentration of VOCs pass through the biodegradation tower. The gas enters the tower from bottom to top, and the biological bacteria liquid fully contacts the gas in the tower from top to bottom. Under the action of the biological bacteria liquid, the organic matter in the exhaust gas is repeatedly captured and enters the liquid phase. Under the action of microbial assimilation and co-metabolism, the VOCs gas in the liquid phase is converted into microbial entities, CO2 and water; after the adsorbed gas passes through the gas-water separator, the water in the gas is separated and then returned to the biodegradation tower for reuse; the remaining extremely low concentration gas (the VOCs content is about 8%, and the VOCs concentration does not meet the emission standards) enters the molecular sieve adsorption catalytic purification system for further degradation and purification. The purified gas (the VOCs concentration is less than 60mg / m 3 Meet the emission standards) and be discharged into the atmosphere through the chimney.

[0065] The painting waste gas first enters the biodegradation tower. The painting waste gas passes through the original blower in the painting workshop through the air duct and enters the bottom of the bioreactor tower 20 from the waste gas inlet 17 on the left side, and then runs from bottom to top. It fully contacts and reacts with the biological bacteria liquid sprayed from top to bottom through the circulation pump 2 into the spray head 3 in the tower (this way, the contact reaction is more complete and the degradation efficiency is higher). Most of the VOCs in the waste gas are degraded by biological bacteria; then, the waste gas enters the gas-water separator to remove the water mist, and the water in the gas is separated and then returned to the biodegradation tower for reuse; after that, the waste gas enters the molecular sieve adsorption catalytic purification system, and after further purification by molecular sieve adsorption + desorption-catalytic combustion, it meets the emission standards.

[0066] The working process of the molecular sieve adsorption catalytic purification system 9 is as follows:

[0067] The waste gas after dehumidification by the gas-water separator first enters the molecular sieve adsorption bed 10 for adsorption. After the saturated molecular sieve is desorbed by hot air and catalytically burned, the organic waste gas adsorbed thereon is burned to generate CO2 and H2O, which are then sent into the chimney through the fan 15 (suction fan) to be discharged into the atmosphere after purification meets the standards; the molecular sieve regains its adsorption capacity and is recycled.

[0068] The desorbed exhaust gas is first preheated by a preheater, and then heated to 250-300°C by an electric heater in the catalytic combustion bed. It is burned under the action of a catalyst, and the gas after combustion meets the emission standards. The molecular sieve adsorption catalytic purification system has 5 molecular sieve adsorption beds, 4 of which are working. When one of them is saturated, the molecular sieve adsorption bed is stopped and the fifth molecular sieve adsorption bed is started. The stopped molecular sieve adsorption bed starts to desorb hot air, opens the desorption air valve 11, and the desorbed gas enters the catalytic oxidation furnace 13 (i.e., the catalytic combustion bed) for catalytic oxidation combustion. The gas after combustion treatment has been purified to meet the standards, and finally enters the chimney through the fan 15 to be discharged into the atmosphere.

[0069] The high-temperature air of the catalytic combustion bed is used to heat the molecular sieve. The high-concentration organic matter adsorbed in the pores of the molecular sieve reaches the boiling point and then leaves the molecular sieve. The desorbed high-concentration exhaust gas is sent to the catalytic combustion bed for high-temperature oxidation. The high-temperature oxidation temperature of the catalytic combustion bed is 250℃~300℃.

[0070] Due to the large air volume of 200,000 m3 / h, this scheme adopts two molecular sieve adsorption catalytic purification systems, with a single processing capacity of 100,000 m3 / h; a single set of 5 uses and one desorption process, a single set of filtration area of ​​28.8m2, filtration adsorption wind speed: 0.97m / s; the molecular sieve filling thickness is 0.6m, effective adsorption time: 0.62s, two sets of purification systems are arranged in parallel, and the two systems run at the same time, so as to meet the processing capacity of 200,000 m3 per hour; that is, the system is equipped with six molecular sieve adsorption boxes, five adsorption and one desorption or standby. During the painting work, adsorption boxes A, B / C / D / E are turned on and run (adsorption box F is desorption or standby). When adsorption box A reaches saturation, it automatically switches to the adsorption-desorption program: adsorption box A stops air intake and enters the desorption program, while adsorption box B starts air intake and enters the adsorption program.

[0071] Automatic adsorption-desorption is controlled by a PLC controller. The signal input end of the PLC controller is connected to a pressure difference sensor provided on the exhaust gas pipeline, and the signal output end is connected to the adsorption air valve 12 and the desorption air valve 11 respectively.

[0072] The bacterial species in the biological bacterial liquid used in the biodegradation treatment system are one or both of Beyerlinckia LM-W and Brevimonas LM-R, which can capture, disperse and degrade the waste gas.

[0073] The microbial liquid of the biodegradation treatment system 1 can be fully mixed with the VOC air waste gas, and the liquid-gas contact time reaches more than 3S, which can achieve the removal and purification of VOCs; the gas-water separator 6 can remove moisture and impurities in the air, improve the dryness and cleanliness of the air and reduce wind resistance, while extending the life of the molecular sieve in the subsequent molecular sieve adsorption catalytic purification system 9 and reducing the subsequent reaction time.

[0074] An automatic detection system is installed in the biodegradation tower to regularly detect the pH value, dissolved oxygen, TDS and other parameters of the bacterial liquid to ensure that all parameters are within the optimal range. The temperature, pH value and dissolved oxygen of the biodegradation tower are automatically controlled by the PLC controller. In order to ensure the temperature of the biodegradation treatment system, after the overall equipment is put into place, the external building is insulated and the roof is equipped with solar panels to reduce energy consumption. This measure is a one-time investment, saving energy and reducing costs. The treatment efficiency (degradation efficiency) of the biodegradation tower reaches 75-90%.

[0075] In summary, the continuous treatment system for painting waste gas described in Example 1 and Example 2 of the utility model can continuously produce online and efficiently degrade VOCs in painting waste gas, and the emission can meet the standards after treatment. In addition, it has low energy consumption, low carbon emission reduction, cost reduction and efficiency improvement, safety and environmental protection, and can meet the needs of enterprises for continuous production and online degradation of VOCs.

[0076] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A continuous treatment system for coating waste gas, characterized in that: It comprises a biodegradation treatment system, a gas-water separator, a molecular sieve adsorption catalytic purification system and a fan connected in sequence; the biodegradation treatment system can make the VOCs waste gas entering the bottom of the biodegradation tower and running from bottom to top fully contact and react with the biological bacteria liquid sprayed from top to bottom in a mist form to obtain a first purified gas that degrades and removes most of the VOCs; the gas-water separator can remove moisture and impurities from the first purified gas to obtain a second purified gas; the molecular sieve adsorption catalytic purification system can further adsorb and burn the second purified gas to purify it to meet the emission standards.

2. A continuous treatment system for coating waste gas according to claim 1, characterized in that: The biodegradation treatment system comprises a biodegradation tower, an aeration device, a biological bacterial liquid circulation system and a filter material layer; the biodegradation tower is a closed horizontal tower, and the bottom of the tower is filled with biological bacterial liquid; the aeration device is an oxygen supply fan, which is located outside the biodegradation tower, and its outlet pipe is connected to the bottom of the tower to supply oxygen to the biological bacteria; the biological bacterial liquid circulation system comprises a circulating water pump and a vertical spray pipe and a spray head connected to its outlet; the circulating water pump is arranged at the bottom of the biodegradation tower, and the spray head is arranged at the top of the biodegradation tower; waste gas is arranged on both sides of the biodegradation tower The tower has an inlet and an exhaust gas outlet, the exhaust gas inlet is located at the top of one side of the tower, and the exhaust gas outlet is located at the top of the other side of the tower; the filter material layer is filled with porous filter material; a vertical air inlet channel is arranged near the exhaust gas inlet in the tower, and the exhaust gas enters the bottom of the tower through the air inlet channel; the remaining middle and upper space in the tower is divided into multiple reaction chambers by multiple filter material layers arranged in parallel at vertical intervals, and each reaction chamber is equipped with a set of biological bacteria liquid circulation system including a circulating water pump and a vertical spray pipe and a spray head connected to its outlet, and the spray heads are symmetrically arranged at different heights on the vertical spray pipe.

3. A continuous painting waste gas treatment system according to claim 2, characterized in that: The bacterial species in the biological bacterial liquid are one or both of Beyerlinckia LM-W and Brevimonas LM-R.

4. A continuous painting waste gas treatment system according to claim 2 or 3, characterized in that: The gas-water separator comprises an air inlet chamber, a condensation chamber and an air-water separation chamber; the air inlet chamber is separated from the air-water separation chamber; the condensation chamber is located below the air inlet chamber and the air-water separation chamber; the air inlet is located at the top of the air inlet chamber of the gas-water separator, and the air outlet is located at the top of the air-water separation chamber; filter cotton is provided at the upper part of the air-water separation chamber, and filler filter stones are provided at the lower part.

5. A continuous painting waste gas treatment system according to claim 2 or 3, characterized in that: The molecular sieve adsorption catalytic purification system comprises a molecular sieve adsorption bed and a catalytic combustion bed; the molecular sieve adsorption beds are multiple and connected in parallel; the air inlet of the molecular sieve adsorption catalytic purification system is respectively connected with the inlet of each molecular sieve adsorption bed; the air outlet of the molecular sieve adsorption catalytic purification system is respectively connected with the outlet of each molecular sieve adsorption bed; an adsorption air valve is provided at the inlet of each molecular sieve adsorption bed, and a desorption air valve is provided at the outlet; the inlet of the catalytic combustion bed is respectively connected with the outlet of each molecular sieve adsorption bed; the outlet of the catalytic combustion bed is connected with the air outlet of the molecular sieve adsorption catalytic purification system; the catalytic combustion bed is provided with an electric heater and a catalyst; and the air outlet of the molecular sieve adsorption catalytic purification system is connected with a fan.

6. A continuous painting waste gas treatment system according to claim 4, characterized in that: The biodegradation treatment system also includes a demister, and a wave plate type demister is arranged at the exhaust gas outlet of the biodegradation tower; the filter cotton is a PP wire mesh demister, and the filler filter stone is a fiber stone filter.

7. A continuous painting waste gas treatment system according to claim 2 or 3, characterized in that: The biodegradation treatment system also includes a pH value control module, a temperature control module and a dissolved oxygen value control module, which automatically controls the pH value, temperature and dissolved oxygen value of the biodegradation tower through a PLC controller; a pH value sensor, a temperature sensor and a dissolved oxygen value sensor are arranged in the biodegradation tower; the signal input end of the temperature controller is connected to the temperature sensor, and the signal output end is connected to the electric heater of the biodegradation tower; the signal input end of the pH value controller is connected to the pH value sensor, and the signal output end is connected to the acid-base tank; the signal input end of the dissolved oxygen controller is connected to the dissolved oxygen value sensor, and the signal output end is connected to the oxygen supply fan.

8. A continuous painting waste gas treatment system according to claim 2 or 3, characterized in that: The molecular sieve adsorption catalytic purification system also includes a preheater and a heat exchanger; the desorption air valve, the preheater and the catalytic combustion bed are connected in sequence; and the outlet of the catalytic combustion bed is connected to the inlet of the fan via the heat exchanger.

9. A continuous painting waste gas treatment system according to claim 4, characterized in that: A biological bacteria circulating water tank is arranged between the gas-water separator and the biodegradation tower; the water outlet at the bottom of the gas-water separator is connected to the inlet of the biological bacteria circulating water tank, and the outlet of the biological bacteria circulating water tank is connected to the biodegradation tower.

10. A continuous painting waste gas treatment system according to claim 5, characterized in that: The molecular sieve adsorption catalytic purification system controls automatic adsorption-desorption through a PLC controller, the signal input end of the PLC controller is connected to a pressure difference sensor arranged on the exhaust gas pipeline, and the signal output end is connected to the adsorption air valve and the desorption air valve respectively.

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