Acrylonitrile tail gas treatment system

Abstract

The utility model discloses an acrylonitrile tail gas treatment system which comprises an enhanced washing tower, a bio-trickling filter, a dehumidifier, ultraviolet photolysis oxidation equipment and activated carbon adsorption and desorption equipment which are sequentially connected, the enhanced washing tower is connected with a washing tower circulating spraying mechanism, and PP Pall ring packing is arranged in the enhanced washing tower; the bio-trickling filter is connected with the trickling filter circulating spraying mechanism, silk-woven filler is arranged in the bio-trickling filter, the trickling filter circulating spraying mechanism is connected with the dosing device, the dehumidifier comprises a surface cooling section and an electric heating section which are connected with the cooling tower, the ultraviolet photolysis oxidation equipment comprises an excimer ultraviolet lamp tube, the activated carbon adsorption and desorption equipment comprises an adsorption and desorption box, and an activated carbon bed layer is arranged in the adsorption and desorption box. The air inlet and outlet of the adsorption and desorption box are connected with the air inlet and outlet header pipe, the desorption port is connected with the backflow header pipe, and the backflow header pipe is connected with the system tail gas inlet pipe and the air inlet and outlet through the vacuum pump. According to the device, biological enhanced washing, biological trickling filtration, dehumidification, excimer photolysis oxidation and activated carbon adsorption and desorption are adopted, tail gas can be discharged after reaching the standard, and the device is efficient and environmentally friendly.

Description

Technical Field

[0001] The utility model relates to the technical field of tail gas treatment, in particular to an acrylonitrile tail gas treatment system. Background Art

[0002] In the prior art, the methods for treating acrylonitrile tail gas generally include high-temperature incineration, biological method, and catalytic incineration. The high-temperature incineration method consumes a lot of fuel and has high cost. The combustion will cause secondary pollution and poor environmental protection. The biological method has a small processing capacity and low efficiency, and has high requirements for tail gas concentration and absorption liquid. The catalytic incineration method has requirements for the calorific value and airflow distribution of the tail gas, is prone to local overheating, has a high failure rate of the device, and the tail gas treatment effect is unstable, and the treatment cost is also high. Utility Model Content

[0003] The utility model aims to solve the technical problems existing in the prior art and provides an acrylonitrile tail gas treatment system, which adopts the treatment process of "bio-enhanced washing + bio-trickling filtration + dehumidification + quasi-molecular photolysis oxidation + activated carbon adsorption and desorption" to ensure that the tail gas meets the emission standards and is highly efficient and environmentally friendly.

[0004] The technical scheme of the utility model is: an acrylonitrile tail gas treatment system, comprising an enhanced washing tower, a biological trickling filter, a dehumidifier, an ultraviolet light deoxidation device, and an activated carbon adsorption and desorption device connected in sequence, wherein the enhanced washing tower is provided with a PP ball ring filler, and the enhanced washing tower is connected with a washing tower circulation spraying mechanism; the biological trickling filter is provided with a silk filler, and the biological trickling filter is connected with a trickling filter circulation spraying mechanism, and the trickling filter circulation spraying mechanism is also connected with a dosing device; the dehumidifier comprises a surface cooling section and an electric heating section, and the surface cooling section is connected with a cooling tower for circulation The cooling water cools down and dehumidifies the wet exhaust gas, and the electric heating section is used to heat the exhaust gas for secondary dehumidification; the ultraviolet light deoxidation equipment includes a number of excimer ultraviolet lamps, and the activated carbon adsorption and desorption equipment includes an adsorption box and a desorption box, and the adsorption box and the desorption box are respectively provided with activated carbon beds, and the air inlets and outlets of the adsorption box and the desorption box are respectively connected to the air inlet main pipe and the air outlet main pipe, and the desorption ports of the adsorption box and the desorption box are respectively connected to the reflux main pipe, and the reflux main pipe is connected to the exhaust inlet pipe at the front end of the enhanced washing tower through a vacuum pump, and valves are respectively installed at each air inlet and outlet and each desorption port.

[0005] Furthermore, the PP ball ring packing described in the utility model is provided with multiple layers above and below; the washing tower circulating spray mechanism comprises a washing tower circulating liquid tank connected to the enhanced washing tower, and a washing tower spray pipe connected to the washing tower circulating liquid tank through a washing tower circulating pump; the washing tower spray pipe has multiple pipes, which are respectively arranged between two adjacent layers of PP ball ring packing, and are used for circulating and spraying the circulating liquid added with microbial surfactant in the washing tower circulating liquid tank.

[0006] Furthermore, the silk woven filler in the utility model is provided with multiple layers above and below, and each layer of the silk woven filler is filled with a roll-shaped body made of silk woven film, and the outer diameter of the roll-shaped body is the same as the inner diameter of the biological trickling filter.

[0007] Furthermore, the specific surface area of ​​the silk woven film in the utility model is 450m 2 / m 3 , Bulk density is 35kg / m 3 , the porosity is 96%.

[0008] Furthermore, the trickling tower circulating spray mechanism described in the utility model includes a trickling tower circulating liquid tank of the biological trickling tower and a trickling tower spray pipe connected to the trickling tower circulating liquid tank through a trickling tower circulating pump, and the trickling tower spray pipe has multiple pipes, which are respectively arranged between two adjacent layers of silk woven filler; the dosing device is connected to the trickling tower circulating liquid tank for adding alkali solution to adjust the pH.

[0009] Furthermore, a temporary water tank is provided between the surface cooling section and the cooling tower of the dehumidifier described in the utility model. The temporary water tank is connected to the dehumidifier through a dehumidification circulation pump. The hot water after heat exchange is temporarily stored in the temporary water tank and then pumped into the cooling tower for cooling. The cold water then enters the dehumidifier for circulation through the temporary water tank.

[0010] Furthermore, thermometers and hygrometers are respectively installed at the inlet and outlet of the dehumidifier described in the utility model.

[0011] Furthermore, the activated carbon bed layer in the utility model adopts columnar bamboo charcoal with a particle size of 3 to 4 mm, and pressure detectors are respectively provided at the air inlet and outlet of the adsorption box and the desorption box.

[0012] Furthermore, the main air outlet pipe in the utility model is connected to the exhaust device through a centrifugal fan.

[0013] Compared with the prior art, the utility model has the following advantages: the utility model adopts the treatment process of "biological enhanced washing + biological trickling filtration + dehumidification + excimer photolysis oxidation + activated carbon adsorption and desorption" to ensure that the exhaust gas meets the emission standards and is highly efficient and environmentally friendly; enhanced biological washing adds biodegradable surfactants to the circulating liquid on the basis of traditional water washing or alkaline washing, which can improve the enhanced washing effect; biological trickling filtration adopts a vertical trickling tower as the reactor type, and a porous filler is arranged in the tower, and a silk filler is selected, which has sufficient specific surface area to meet the needs of microbial growth. At the same time, due to its excellent biofilm performance and unique structural advantages, it has a smaller penetration resistance than other types of filter materials, and its strength is sufficient and not easy to collapse. Acid will be produced after growth and metabolism. The added alkali solution can adjust the pH so that the microorganisms can volatilize more effectively in a suitable pH environment. The dehumidifier adopts the principle of freezing and dehumidification, which can reduce the humidity of the exhaust gas for subsequent reactions. The added temporary water tank can effectively reduce the impact of fluctuations in the inlet temperature and humidity parameters on the operation of the cooling tower, ensuring the stable operation of the dehumidifier. The dehumidified exhaust gas is then treated by ultraviolet light deoxidation equipment and then enters the activated carbon adsorption and desorption equipment. Two carbon boxes are switched for use, one for adsorption and the other for desorption. The carbon box is equipped with a pressure difference indicator to facilitate judgment of whether the activated carbon is blocked or saturated with adsorption. The saturated activated carbon is regenerated by vacuum analysis, and the analyzed high-concentration gas is returned to the front end of the system for circulation treatment, which not only ensures efficient treatment of the exhaust gas, but also avoids polluting the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the system connection diagram of the utility model;

[0015] Figure 2 It is a schematic diagram of the specific structure of the activated carbon adsorption and desorption equipment described in the utility model.

[0016] Among them: 1. Enhanced washing tower; 2. Bio-trickling filter; 3. Dehumidifier; 4. Ultraviolet light deoxidation equipment; 5. Activated carbon adsorption and desorption equipment; 6. PP ball ring filler; 7. Washing tower circulating liquid tank; 8. Washing tower circulating pump; 9. Washing tower spray pipe; 10. Silk filler; 11. Trickling filter circulating liquid tank; 12. Trickling filter circulating pump; 13. Trickling filter spray pipe; 14. Dosing device; 15. Cooling tower; 16. Temporary water tank; 17. Dehumidification circulation pump; 18. Adsorption box; 19. Desorption box; 20. Air inlet main pipe; 21. Air outlet main pipe; 22. Reflux main pipe; 23. Vacuum pump; 24. Exhaust gas inlet pipe; 25. Centrifugal fan; 26. Exhaust device. DETAILED DESCRIPTION

[0017] The specific implementation of the utility model is described in detail below with reference to the accompanying drawings.

[0018] Example:

[0019] The accompanying drawings show a specific implementation of an acrylonitrile tail gas treatment system of the utility model, as shown in FIG. Figure 1 It mainly includes an enhanced washing tower 1, a biological trickling filter 2, a dehumidifier 3, an ultraviolet light deoxidation device 4, and an activated carbon adsorption and desorption device 5 which are connected in sequence.

[0020] A three-layer PP ball ring packing 6 is arranged in the enhanced washing tower 1, and a washing tower circulating spray mechanism is connected to the enhanced washing tower 1. The washing tower circulating spray mechanism comprises a washing tower circulating liquid tank 7 connected to the enhanced washing tower 1, and a washing tower spray pipe 9 connected to the washing tower circulating liquid tank 7 through a washing tower circulating pump 8. The washing tower spray pipe 9 has two pipes, which are respectively arranged between two adjacent layers of PP ball ring packing 6, and are used for circulating and spraying the circulating liquid in the washing tower circulating liquid tank 7 to which a microbial surfactant is added.

[0021] Enhanced biological washing can improve the enhanced washing effect by adding biodegradable surfactants to the circulating liquid. The circulating liquid is sent to the tower through the washing tower circulating pump 8, and the tail gas enters from the bottom of the tower and contacts the circulating liquid in reverse. The concentration of the circulating liquid gradually increases during the spraying process, and it can be discharged regularly, and fresh water and reagents can be added.

[0022] The bio-trickling filter 2 is provided with three layers of silk packing 10, each layer of silk packing 10 is made of a silk film rolled body, the outer diameter of the rolled body is the same as the inner diameter of the bio-trickling filter 2, so that the airflow can pass through the silk packing 10 without dead corners or short flow. The specific surface area of ​​the silk film is 450m 2 / m 3 , Bulk density is 35kg / m 3 , the porosity is 96%, which has sufficient specific surface area to meet the needs of microbial growth. At the same time, due to its excellent biofilm performance and unique structural advantages, it has smaller penetration resistance than other types of filter media, and its strength is sufficient and not easy to collapse.

[0023] The biological trickling filter 2 is connected to a trickling filter circulating spray mechanism, which includes a trickling filter circulating liquid tank 11 of the biological trickling filter 2 and a trickling filter spray pipe 13 connected to the trickling filter circulating liquid tank 11 through a trickling filter circulating pump 12. The trickling filter spray pipe 13 has two pipes, which are respectively arranged between two adjacent layers of silk woven packing 10. The circulating liquid is delivered to the tower through the trickling filter circulating pump 12, and the tail gas enters from the bottom of the tower and contacts the circulating liquid in reverse direction.

[0024] The trickling tower circulating liquid tank 11 is also connected to a dosing device 14, which is used to add alkali solution. Microorganisms will produce acid after growth and metabolism. The added alkali solution can adjust the pH so that the microorganisms can volatilize more effectively in a suitable pH environment.

[0025] After effective biofilm formation, microorganisms grow on the surface of the silk filler 10. Excessive biofilm proliferation can easily cause the biofilm to thicken, resulting in blockage of the filler pores, and further trigger the deep microorganisms to change from aerobic bacteria to facultative anaerobic bacteria or even anaerobic bacteria, which deteriorates the system. Therefore, high-porosity fillers and appropriate spraying and flushing help control the proliferation of microorganisms and avoid adverse consequences caused by excessive proliferation. After environmental conditions change, some microorganisms will die, and some can continue to survive. The surviving microorganisms can develop into dominant bacteria after a short period of reproduction. The biological trickling filter 2 of this system can withstand shock loads. When the concentration of pollutants increases, the treatment effect decreases in a short period of time, but it can return to normal quickly.

[0026] The dehumidifier 3 includes a surface cooling section and an electric heating section. The surface cooling section is connected to the cooling tower 15 through a temporary water tank 16. The temporary water tank 16 is connected to the dehumidifier 3 through a dehumidification circulation pump 17. After the humid exhaust gas enters the dehumidifier 3, it is first cooled and dehumidified by the surface cooling section, and then heated by the electric heating section for secondary dehumidification. The cooling tower 15 provides circulating cooling water for the surface cooling section. The hot water after heat exchange in the surface cooling section is temporarily stored in the temporary water tank 16 and then pumped into the cooling tower 15 for cooling. The cold water then enters the dehumidifier 3 through the temporary water tank 16 for circulation.

[0027] The dehumidifier adopts the principle of freezing and dehumidification, which can reduce the humidity of the exhaust gas for subsequent reaction. The added temporary storage water tank 16 can effectively reduce the impact of the fluctuation of the inlet air temperature and humidity parameters on the operation of the cooling tower 15, ensuring the stable operation of the dehumidifier 3.

[0028] Thermometers and hygrometers are installed at the inlet and outlet of the dehumidifier 3, respectively, so that the operation of the equipment can be observed in real time.

[0029] The ultraviolet light deoxidation device 4 includes a number of excimer ultraviolet lamps. The wavelength of the conventional low-pressure mercury lamps on the market is 185 or 254nm. The excimer ultraviolet lamps of the utility model can emit light with a wavelength of 172nm, which has high energy and can break molecular bonds of higher energy levels, thus achieving better waste gas treatment effects. The dehumidified tail gas is treated by the ultraviolet light deoxidation device 4 and then enters the activated carbon adsorption and desorption device 5.

[0030] The activated carbon adsorption and desorption equipment 5 includes an adsorption box 18 and a desorption box 19, which are switched to use, one for adsorption and the other for desorption. The adsorption box 18 and the desorption box 19 are respectively provided with an activated carbon bed layer, and the activated carbon bed layer uses columnar bamboo charcoal with a particle size of 3 to 4 mm, which has the advantages of high strength, large specific surface area, high adsorption capacity, fast adsorption speed, developed pore structure, and pore size lower than coal-based carbon, and is suitable for adsorbing small molecular weight organic matter. When the tail gas passes through the activated carbon bed layer, the organic pollutants are adsorbed by the microporous structure in the activated carbon, and the clean gas passes through the bed layer and is discharged.

[0031] In this embodiment, combined with Figure 2The adsorption box 18 has an air inlet 201A at the bottom, an air outlet 101A at the top, and a desorption port 301A in the middle. The desorption box 19 has an air inlet 201B at the bottom, an air outlet 101B at the top, and a desorption port 301B in the middle. Pressure detectors are provided at the air inlet 201A, the air outlet 101A, the air inlet 201B, and the air outlet 101B, respectively, to determine whether the activated carbon is blocked or adsorption saturated according to the pressure difference.

[0032] The air inlet 201A and the air inlet 201B are connected to the air inlet main 20, the air outlet 101A and the air outlet 101B are connected to the air outlet main 21, the desorption port 301A and the desorption port 301B are connected to the reflux main 22, and the reflux main 22 is connected to the tail gas inlet pipe 24 at the front end of the enhanced washing tower 1 through the vacuum pump 23. Valves are installed at each air inlet and outlet and each desorption port. When the adsorption box 18 is adsorbing and the desorption box 19 is desorbing, the air inlet 201A and the air outlet 101A are opened, the desorption port 301A is closed, and the gas in the air inlet manifold 20 enters the adsorption box 18, and the clean gas is discharged from the air outlet manifold 21; at this time, the air inlet 201B and the air outlet 101B of the desorption box 19 are closed, and the exhaust gas does not pass through the desorption box 19. The desorption port 301B is opened, and the vacuum pump 23 is working. The air in the desorption box 19 is pumped away through the reflux manifold 22. After the vacuum pump 23 pumps for a certain period of time, the desorption regeneration of the adsorbed saturated activated carbon is completed, and the extracted high-concentration gas returns to the tail gas inlet pipe 24 at the front end of the system for cyclic treatment. In the next round of work, the valve is switched, and the desorption box 19 is used for adsorption, and the adsorption box 18 is used for desorption again, so as to achieve efficient treatment of the tail gas.

[0033] The air outlet main pipe 21 is also connected to an exhaust device 26 via a centrifugal fan 25. The exhaust device 26 is an exhaust chimney or an exhaust pipe.

[0034] Of course, the above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot be used to limit the protection scope of the utility model. Any modifications made according to the spirit of the main technical solution of the utility model should be included in the protection scope of the utility model.

Claims

1. An acrylonitrile tail gas treatment system, characterized in that: The invention comprises an enhanced washing tower (1), a biological trickling filter (2), a dehumidifier (3), an ultraviolet light deoxidation device (4), and an activated carbon adsorption and desorption device (5) which are connected in sequence. The enhanced washing tower (1) is provided with a PP ball ring filler (6), and the enhanced washing tower (1) is connected to a washing tower circulation spraying mechanism; the biological trickling filter (2) is provided with a silk filler (10), and the biological trickling filter (2) is connected to a trickling filter circulation spraying mechanism, and the trickling filter circulation spraying mechanism is also connected to a dosing device (14); the dehumidifier (3) comprises a surface cooling section and an electric heating section, the surface cooling section is connected to a cooling tower (15) for circulating cooling water to cool and dehumidify the humid tail gas, and the electric heating section is used to add The hot tail gas is subjected to secondary dehumidification; the ultraviolet light deoxidation device (4) comprises a plurality of excimer ultraviolet lamps, and the activated carbon adsorption and desorption device (5) comprises an adsorption box (18) and a desorption box (19), wherein the adsorption box (18) and the desorption box (19) are respectively provided with activated carbon beds, the air inlets and outlets of the adsorption box (18) and the desorption box (19) are respectively connected to an air inlet main pipe (20) and an air outlet main pipe (21), and the desorption ports of the adsorption box (18) and the desorption box (19) are respectively connected to a reflux main pipe (22), and the reflux main pipe (22) is connected to an exhaust gas inlet pipe (24) at the front end of the enhanced washing tower (1) via a vacuum pump (23), and valves are respectively installed at each air inlet and outlet and each desorption port.

2. The acrylonitrile tail gas treatment system according to claim 1, characterized in that: The PP ball ring packing (6) is provided with multiple layers above and below; the washing tower circulation spraying mechanism comprises a washing tower circulation liquid tank (7) connected to the enhanced washing tower (1), and a washing tower spraying pipe (9) connected to the washing tower circulation liquid tank (7) via a washing tower circulation pump (8); the washing tower spraying pipe (9) has a plurality of pipes, which are respectively provided between two adjacent layers of the PP ball ring packing (6) and are used for circulating and spraying the circulating liquid added with the microbial surfactant in the washing tower circulation liquid tank (7).

3. The acrylonitrile tail gas treatment system according to claim 1, characterized in that: The woven silk filler (10) is provided with multiple layers above and below, and each layer of the woven silk filler (10) is filled with a roll-shaped body made of a woven silk film, and the outer diameter of the roll-shaped body is the same as the inner diameter of the biological trickling filter (2).

4. The acrylonitrile tail gas treatment system according to claim 3, characterized in that: The specific surface area of ​​the silk film is 450 m 2 / m 3 , Bulk density is 35kg / m 3 , the porosity is 96%.

5. The acrylonitrile tail gas treatment system according to claim 3, characterized in that: The trickling tower circulation spray mechanism comprises a trickling tower circulation liquid tank (11) connected to the biological trickling tower (2), a trickling tower spray pipe (13) connected to the trickling tower circulation liquid tank (11) via a trickling tower circulation pump (12), the trickling tower spray pipe (13) having a plurality of pipes, each of which is arranged between two adjacent layers of silk woven fillers (10); the dosing device (14) is connected to the trickling tower circulation liquid tank (11) and is used for adding alkali solution to adjust pH.

6. The acrylonitrile tail gas treatment system according to claim 1, characterized in that: A temporary water tank (16) is provided between the surface cooling section of the dehumidifier (3) and the cooling tower (15). The temporary water tank (16) is connected to the dehumidifier (3) via a dehumidification circulation pump (17). The hot water after heat exchange is temporarily stored in the temporary water tank (16) and then pumped into the cooling tower (15) for cooling. The cooling water then enters the dehumidifier (3) for circulation via the temporary water tank (16).

7. The acrylonitrile tail gas treatment system according to claim 1, characterized in that: The inlet and outlet of the dehumidifier (3) are respectively equipped with thermometers and hygrometers.

8. The acrylonitrile tail gas treatment system according to claim 1, characterized in that: The activated carbon bed layer uses columnar bamboo charcoal with a particle size of 3 to 4 mm. Pressure detectors are respectively provided at the air inlets and outlets of the adsorption box (18) and the desorption box (19).

9. The acrylonitrile tail gas treatment system according to claim 1, characterized in that: The main air outlet pipe (21) is connected to an exhaust device (26) via a centrifugal fan (25).

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