Waste gas treatment device and waste gas treatment method

Abstract

The present invention relates to a waste gas treatment device and a waste gas treatment method, wherein the waste gas treatment device comprises: an absorption tower (1), a tower bottom liquid circulation unit (2), and a gas circulation unit (3); the tower bottom liquid circulation unit (2) is respectively connected to a tower bottom liquid outlet (11) and a tower bottom liquid circulation inlet (12) on the absorption tower (1); the gas circulation unit (3) is respectively connected to a waste gas inlet (13) and a gas outlet (14) on the absorption tower (1). The absorption liquid enters the tower in layers, and the waste gas is fully contacted with the absorption liquid in the tower for absorption reaction through fillers, liquid collectors, and liquid distributors, thereby achieving a treatment effect, effectively eliminating the entrainment of waste gas mist, and ensuring that the treated gas meets the emission standards.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to a waste gas treatment device and a waste gas treatment method. Background Art

[0002] In the process of industrial production, a large amount of industrial waste gas is usually generated, which usually contains a large amount of harmful gases. If directly discharged into the atmosphere, it will seriously harm the atmospheric environment. For example, in the production process of polyvinyl alcohol, a large amount of acid gas is generated during the distillation and filtration process (such as pressing and discharging carbon powder, distillation residue slag, etc.). Since the distillation and filtration process adopts intermittent operation, the acid gas collection and treatment is difficult and the investment cost is high. It is necessary to design an effective waste gas collection and treatment device and method. Summary of the invention

[0003] The object of the present invention is to provide a waste gas treatment device and a waste gas treatment method for effectively treating waste gas.

[0004] To achieve the above-mentioned purpose, the present invention provides a waste gas treatment device, comprising: an absorption tower, a bottom liquid circulation unit, and a gas circulation unit;

[0005] The tower bottom liquid circulation unit is respectively connected to the tower bottom liquid outlet and the tower bottom liquid circulation inlet on the absorption tower;

[0006] The gas circulation unit is respectively connected to the waste gas inlet and the gas outlet on the absorption tower.

[0007] According to one aspect of the present invention, the absorption tower is further provided with an absorption liquid inlet for inputting absorption liquid, and along the vertical direction, the absorption liquid inlet is located between the exhaust gas inlet and the tower bottom liquid circulation inlet.

[0008] According to one aspect of the present invention, multiple packing layers are arranged inside the absorption tower along the vertical direction, and liquid collectors and liquid distributors are selectively arranged between the packing layers.

[0009] According to one aspect of the present invention, a demister is further provided inside the absorption tower in the vertical direction, and the demister is located above the packing layer, the liquid collector and the liquid distributor.

[0010] According to one aspect of the present invention, the packing layer is provided with six layers;

[0011] Inside the absorption tower, from top to bottom, there are respectively a first packing layer, a second packing layer, a third packing layer, a fourth packing layer, a fifth packing layer, and a sixth packing layer;

[0012] In the vertical direction, the exhaust gas inlet is located below the sixth packing layer, and the absorption liquid inlet is located between the fifth packing layer and the sixth packing layer.

[0013] According to one aspect of the present invention, the tower bottom liquid circulation inlet is provided with two;

[0014] In the vertical direction, the tower bottom liquid circulation inlet is arranged on the upper and lower sides of the first packing layer respectively.

[0015] According to one aspect of the present invention, the liquid collector is respectively arranged between the first packing layer and the second packing layer, between the second packing layer and the third packing layer, between the third packing layer and the fourth packing layer, and between the fourth packing layer and the fifth packing layer;

[0016] The liquid distributors are respectively arranged between the first packing layer and the second packing layer, between the second packing layer and the third packing layer, between the third packing layer and the fourth packing layer, and between the fourth packing layer and the fifth packing layer.

[0017] According to one aspect of the present invention, between adjacent packing layers, the liquid collector is located above the liquid distributor.

[0018] According to one aspect of the present invention, the packing layer uses BHS II type packing.

[0019] According to one aspect of the present invention, the demister is a wire mesh demister.

[0020] According to one aspect of the present invention, the bottom liquid circulation unit includes: a pump body, a first pipeline connected to the pump body inlet and the bottom liquid outlet, a first control pipeline connected to the pump body outlet, a second pipeline connected to the first control pipeline and the bottom liquid circulation inlet, and a third pipeline connected to the first control pipeline and the outside.

[0021] According to one aspect of the present invention, the gas circulation unit includes: an induced draft fan, a fourth pipeline connected to the induced draft fan inlet and the gas exhaust outlet, a fifth pipeline connected to the induced draft fan outlet and the exhaust gas inlet, and a second control pipeline connected to the induced draft fan outlet and the outside.

[0022] According to one aspect of the present invention, it also includes: a control device; the control device is used to monitor the bottom liquid index in the bottom liquid circulation unit and control the first control pipeline, to monitor the gas index in the pipeline of the gas circulation unit and control the second control pipeline, and to control the regulating valve at the absorption liquid inlet of the absorption tower.

[0023] To achieve the above object of the invention, the present invention provides a waste gas treatment method, comprising the following steps:

[0024] S1. The waste gas to be treated is introduced into the outside through the waste gas inlet on the absorption tower, and the fresh absorption liquid is introduced into the outside through the absorption liquid inlet on the absorption tower;

[0025] S2. The bottom liquid circulation unit and the gas circulation unit are started respectively, and when the amount of fresh absorption liquid introduced into the absorption tower reaches the preset requirement, the absorption liquid inlet is closed;

[0026] S3. The bottom liquid circulation unit pumps the bottom liquid to the upper end of the absorption tower, and the bottom liquid flows from top to bottom and contacts the exhaust gas flowing from bottom to top;

[0027] S4. The exhaust gas enters the gas circulation unit through the gas outlet, and the control device monitors whether the exhaust gas index meets the standard. If so, the second control pipeline is opened and the exhaust gas is discharged to the outside. Otherwise, the second control pipeline remains closed and the exhaust gas is re-input into the absorption tower through the fifth pipeline;

[0028] S5. The control device monitors whether the index of the bottom liquid meets the requirement of purifying the exhaust gas. If so, the first control pipeline is controlled to keep the second pipeline connected to the pump body. Otherwise, the first control pipeline is controlled to connect the third pipeline to the pump body to discharge the bottom liquid, and the absorption liquid inlet is opened to replenish fresh absorption liquid from the outside.

[0029] According to one aspect of the present invention, in step S5, in the step of discharging the bottom liquid, the bottom liquid is tested, and if the bottom liquid is qualified, it is input into a sewage treatment device, otherwise, the bottom liquid is input into a sedimentation tank for collection and treatment, and finally sent to a sewage treatment device.

[0030] According to one scheme of the present invention, the absorption liquid enters the tower in layers, and the waste gas is fully contacted and absorbed by the absorption liquid in the tower through the filler, liquid collector and liquid distributor, thereby achieving the treatment effect, effectively eliminating the entrainment of waste gas mist and ensuring that the treated gas meets the emission standards.

[0031] According to one scheme of the present invention, by setting the absorption liquid inlet above the exhaust gas inlet, while the absorption liquid and exhaust gas are input, the absorption liquid flows downward under the action of gravity, and the exhaust gas flows upward and contacts with the absorption liquid, thereby realizing one-time treatment of the exhaust gas by the absorption liquid. This arrangement is conducive to improving the efficiency of the present invention in purifying exhaust gas and avoiding the number of repeated cycles of exhaust gas.

[0032] According to one solution of the present invention, through the above-mentioned setting, a packing layer is set in the absorption tower so that the absorption liquid and the waste gas can be evenly distributed when encountering the packing layer, so that the waste gas and the absorption liquid can be more easily contacted in the packing layer, so that the absorption liquid can more fully and quickly absorb the harmful gases in the waste gas, thereby achieving the beneficial effect of purifying the waste gas. In addition, by setting a liquid collector and a liquid distributor, the contact time between the absorption liquid and the waste gas is longer, and the distribution of the absorption liquid is more uniform during the downward flow of the absorption liquid.

[0033] According to one solution of the present invention, a demister is provided to filter out the liquid in the gas before the gas is discharged from the absorption tower. This is beneficial to the extraction of gas by the gas circulation unit and also avoids the corrosion of the entire gas circulation unit by the liquid contained in the gas, thereby improving the operating stability and service life of the entire equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The figure schematically shows the structure of an exhaust gas treatment device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0037] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0038] like Figure 1As shown, according to one embodiment of the present invention, a waste gas treatment device of the present invention comprises: an absorption tower 1, a bottom liquid circulation unit 2, and a gas circulation unit 3. In this embodiment, the bottom liquid circulation unit 2 is respectively connected to the bottom liquid outlet 11 and the bottom liquid circulation inlet 12 on the absorption tower 1. In this embodiment, the gas circulation unit 3 is respectively connected to the waste gas inlet 13 and the gas outlet 14 on the absorption tower 1.

[0039] According to the present invention, by setting up an absorption tower to perform closed treatment of waste gas, leakage of polluting gas during waste gas treatment is avoided, which has a beneficial effect on improving the purification rate of waste gas and protecting the environment. In addition, by setting up the tower bottom liquid circulation unit 2, the tower bottom liquid can be continuously circulated, which can further improve the use efficiency of the tower bottom liquid, which is not only beneficial to purifying gas, but also reduces the output of waste liquid and reduces the material cost during waste gas treatment.

[0040] like Figure 1 As shown, according to one embodiment of the present invention, the absorption tower 1 is further provided with an absorption liquid inlet 15 for inputting absorption liquid, and along the vertical direction, the absorption liquid inlet 15 is located between the exhaust gas inlet 13 and the tower bottom liquid circulation inlet 12.

[0041] According to the present invention, by setting the absorption liquid inlet 15 above the exhaust gas inlet 13, while the absorption liquid and exhaust gas are input, the absorption liquid flows downward under the action of gravity, and the exhaust gas flows upward and contacts with the absorption liquid, thereby realizing one-time treatment of the exhaust gas by the absorption liquid. This arrangement is beneficial to improving the efficiency of the present invention in purifying exhaust gas and avoiding the number of repeated cycles of exhaust gas.

[0042] like Figure 1 As shown, according to one embodiment of the present invention, multiple packing layers 16 are arranged inside the absorption tower 1 in the vertical direction, and liquid collectors 17 and liquid distributors 18 are selectively arranged between the packing layers 16. In this embodiment, the liquid collectors 17 and liquid distributors 18 are selectively arranged between the packing layers 16, which means that the liquid collectors 17 and liquid distributors 18 can be arranged between any two adjacent packing layers 16 according to actual work needs. In this embodiment, the material of the packing layer 16 adopts BHS II type packing.

[0043] According to the present invention, through the above-mentioned setting, a packing layer is set in the absorption tower so that the absorption liquid and the waste gas can be evenly distributed when encountering the packing layer, so that the waste gas and the absorption liquid can be more easily contacted in the packing layer, so that the absorption liquid can more fully and quickly absorb the harmful gas in the waste gas, thereby achieving the beneficial effect of purifying the waste gas. In addition, by setting the liquid collector 17 and the liquid distributor 18, the contact time between the absorption liquid and the waste gas is longer, and the distribution of the absorption liquid is more uniform during the downward flow of the absorption liquid.

[0044] like Figure 1 As shown, according to one embodiment of the present invention, a demister 19 is further provided inside the absorption tower 1 in the vertical direction, and the demister 19 is located above the packing layer 16, the liquid collector 17 and the liquid distributor 18. In this embodiment, the gas outlet 14 is located at the top of the absorption tower 1, and the demister 19 is located below the gas outlet 14. In this embodiment, the demister 19 is a wire mesh demister. Preferably, the demister 19 can adopt a BHCW wire mesh demister.

[0045] According to the present invention, by setting up a demister 19, the liquid in the gas is filtered out before the gas is discharged from the absorption tower, which is beneficial to the extraction of gas by the gas circulation unit 3 and also avoids the corrosion of the entire gas circulation unit 3 by the liquid contained in the gas, thereby improving the operating stability and service life of the entire equipment.

[0046] like Figure 1 As shown, according to one embodiment of the present invention, the packing layer 16 is provided with six layers. In this embodiment, inside the absorption tower 1, from top to bottom, there are the first packing layer 161, the second packing layer 162, the third packing layer 163, the fourth packing layer 164, the fifth packing layer 165, and the sixth packing layer 166. In this embodiment, in the vertical direction, the exhaust gas inlet 13 is located below the sixth packing layer 166, and the absorption liquid inlet 15 is located between the fifth packing layer 165 and the sixth packing layer 166. Through the above arrangement, the exhaust gas and the fresh absorption liquid are mixed and contacted in the sixth packing layer 166 to achieve the effect of purifying the exhaust gas once.

[0047] like Figure 1 As shown, according to one embodiment of the present invention, two bottom liquid circulation inlets 12 are provided. In this embodiment, along the vertical direction, the bottom liquid circulation inlets 12 are arranged on the upper and lower sides of the first packing layer 161 respectively.

[0048] According to the present invention, by providing multiple bottom liquid circulation inlets 12, the circulating bottom liquid (i.e., formed by the fresh absorption liquid contacting the waste gas) can contact the waste gas at different positions, thereby achieving the effect of step-by-step purification of the waste gas. In particular, since the purification effect of the bottom liquid is lower than that of the fresh absorption liquid, the arrangement of multiple bottom liquid circulation inlets 12 can achieve the best purification effect of the bottom liquid, so that the qualified rate of the waste gas passing through the present invention is higher, the number of cycles of the waste gas is reduced, and the purification efficiency of the entire device is improved.

[0049] like Figure 1 As shown, according to one embodiment of the present invention, the liquid collector 17 is respectively arranged between the first packing layer 161 and the second packing layer 162, between the second packing layer 162 and the third packing layer 163, between the third packing layer 163 and the fourth packing layer 164, and between the fourth packing layer 164 and the fifth packing layer 165. In this embodiment, the liquid distributor 18 is respectively arranged between the first packing layer 161 and the second packing layer 162, between the second packing layer 162 and the third packing layer 163, between the third packing layer 163 and the fourth packing layer 164, and between the fourth packing layer 164 and the fifth packing layer 165. In this embodiment, between adjacent packing layers 16, the liquid collector 17 is located above the liquid distributor 18.

[0050] According to the present invention, through the above-mentioned setting, the liquid collector 17 is selectively set between adjacent packing layers so that the liquid passing through the packing layer can be gathered, so that the gas reaching the upper packing layer has a pre-washing effect, and then the pre-washed gas can be further absorbed by the liquid in the packing layer after entering the packing layer, so that the waste gas treatment process of the present invention is more sufficient and the purification efficiency is higher. In addition, by setting the liquid distributor 18, the liquid in the liquid collector 17 can be evenly distributed in the next packing layer, so that the liquid in the packing layer is evenly distributed, thereby achieving the effect of full contact with the gas and improving the purification efficiency.

[0051] like Figure 1 As shown, according to one embodiment of the present invention, in order to make the bottom liquid in the first packing layer 161 evenly distributed, a liquid distributor 18 can be optionally arranged above the first packing layer 161 to evenly distribute the bottom liquid outflowing from the bottom liquid circulation inlet 12 in the first packing layer 161, so that the contact between the gas in the first packing layer 161 and the bottom liquid is sufficient.

[0052] like Figure 1As shown, according to one embodiment of the present invention, in order to facilitate the inspection and maintenance of the absorption tower of the present invention, a plurality of inspection ports 20 are provided on the tower body of the absorption tower. In the vertical direction, the inspection ports 20 can be provided between the demister 19 and the packing layer, between adjacent packing layers, and between the packing layer and the tower bottom. The unique design of the inspection ports makes the maintenance and inspection of the acid gas treatment device more qualified and convenient.

[0053] like Figure 1 As shown, according to one embodiment of the present invention, the bottom liquid circulation unit 2 includes: a pump body 21, a first pipeline 22 connected to the inlet of the pump body 21 and the bottom liquid outlet 11, a first control pipeline 23 connected to the outlet of the pump body 21, a second pipeline 24 connected to the first control pipeline 23 and the bottom liquid circulation inlet 12, and a third pipeline 25 connected to the first control pipeline 23 and the outside.

[0054] like Figure 1 As shown, according to one embodiment of the present invention, the gas circulation unit 3 includes: an induced draft fan 31, a fourth pipeline 32 connected to the inlet of the induced draft fan 31 and the gas exhaust port 14, a fifth pipeline 33 connected to the outlet of the induced draft fan 31 and the exhaust gas inlet 13, and a second control pipeline 34 connected to the outlet of the induced draft fan 31 and the outside.

[0055] like Figure 1 As shown, according to one embodiment of the present invention, it also includes: a control device; the control device is used to monitor the bottom liquid index in the bottom liquid circulation unit 2 and control the first control pipeline 23, to monitor the gas index in the pipeline of the gas circulation unit 3 and control the second control pipeline 34, and to control the regulating valve of the absorption liquid inlet 15 of the absorption tower 1.

[0056] According to one embodiment of the present invention, a waste gas treatment method of the present invention comprises the following steps:

[0057] S1. The waste gas to be treated is introduced into the outside through the waste gas inlet 13 on the absorption tower 1, and the fresh absorption liquid is introduced into the outside through the absorption liquid inlet 15 on the absorption tower 1;

[0058] S2. The bottom liquid circulation unit 2 and the gas circulation unit 3 are started respectively, and when the amount of fresh absorption liquid introduced into the absorption tower 1 reaches the preset requirement, the absorption liquid inlet 15 is closed;

[0059] S3. The bottom liquid circulation unit 2 pumps the bottom liquid to the upper end of the absorption tower 1, and the bottom liquid flows from top to bottom and contacts the exhaust gas flowing from bottom to top;

[0060] S4. The waste gas enters the gas circulation unit 3 through the gas outlet 14, and the control device monitors whether the waste gas index meets the standard. If so, the second control pipeline 34 is opened and the waste gas is discharged to the outside. Otherwise, the second control pipeline 34 remains closed, and the waste gas is re-input into the absorption tower 1 through the fifth pipeline 33;

[0061] S5. The control device monitors whether the indicators of the bottom liquid meet the requirements for purifying the exhaust gas. If so, the first control pipeline 23 is controlled to keep the second pipeline 24 connected to the pump body 21. Otherwise, the first control pipeline 23 is controlled to connect the third pipeline 25 to the pump body 21 to discharge the bottom liquid, and the absorption liquid inlet 15 is opened to replenish fresh absorption liquid from the outside.

[0062] like Figure 1 As shown, according to one embodiment of the present invention, in step S5, in the step of discharging the bottom liquid, the bottom liquid is tested, and if the bottom liquid is qualified, it is input into the sewage treatment device, otherwise, the bottom liquid is input into the sedimentation tank for sedimentation treatment, and some weakly acidic sewage is already in the sedimentation tank, which is neutralized with the alkaline bottom liquid and finally sent to the sewage treatment device.

[0063] To further illustrate the present invention, the method of the present invention is further described in conjunction with specific embodiments.

[0064] Waste gas (acid gas generated when discharging slag from the slag outlet of the distillation operation process and acid gas generated when unloading carbon powder from the filter chamber) is input into the absorption tower 1 from the waste gas inlet 13, and the waste gas contacts the absorption liquid (alkaline solution) input from the absorption liquid inlet 15 from bottom to top. At the same time, the tower bottom liquid circulation unit 2 makes the tower bottom liquid (alkali liquid) contact the waste gas from top to bottom in the packing layer 16, and performs acid-base neutralization reaction and absorption at the same time. After absorption, the acid concentration of the rising gas is getting lower and lower, and the concentration of the tower bottom liquid (alkali liquid) is also getting lower and lower. When the gas reaches the upper part of the tower, it is dehumidified again by the demister 19 (high-efficiency plastic wire mesh demister) and enters the induced draft fan 31. The induced draft fan 31 continuously extracts the non-condensable gas (purified waste gas) after absorption, and monitors it through the online pH meter. After passing (pH=7), it is directly vented from the second control pipeline 34. If it fails, the gas is recycled. The induced draft fan 31 adopts the DCS system variable frequency control, and the liquid descending in the tower falls into the tower bottom. The tower bottom liquid is recycled through the pump body 21. In this embodiment, when it is detected that the pH value of the tower bottom liquid is not enough for waste gas purification, fresh alkali liquid is introduced from the absorption liquid inlet 15, and the alkali liquid is continuously replenished to ensure that the pH value of the absorption liquid in the tower is alkaline. By controlling the pH value of the circulating liquid, the tower bottom liquid is continuously circulated, neutralized, and discharged regularly according to the pH value. The gas fully absorbed at the top of the tower is discharged into the atmosphere after being qualified by the pH online monitoring, and the unqualified gas is recycled and absorbed. The tower liquid level is controlled by 20-60% according to the situation. When the pH value of the absorption liquid in the tower is ≤11, the tower bottom liquid can be discharged. Depending on the detection situation, if the pH value of the absorption liquid is neutral, it is discharged to the sewage treatment system. If it is weakly alkaline, it is discharged into the sedimentation tank. When the pH value of the absorption liquid is >11, it is strictly forbidden to discharge the absorption liquid under normal circumstances.

[0065] In this embodiment, the component of the absorption liquid is a sodium hydroxide aqueous solution or a sodium acetate aqueous solution.

[0066] The above contents are merely examples of specific solutions of the present invention. For devices and structures not described in detail therein, it should be understood that they can be implemented by adopting general devices and general methods available in the art.

[0067] The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A waste gas treatment device, characterized in that: include: Absorption tower (1), bottom liquid circulation unit (2), gas circulation unit (3); The bottom liquid circulation unit (2) is respectively connected to the bottom liquid outlet (11) and the bottom liquid circulation inlet (12) on the absorption tower (1); The gas circulation unit (3) is respectively connected to the waste gas inlet (13) and the gas outlet (14) on the absorption tower (1); the gas circulation unit (3) comprises an induced draft fan (31); The absorption tower (1) is provided with six packing layers (16) inside, wherein, from top to bottom, they are respectively a first packing layer (161), a second packing layer (162), a third packing layer (163), a fourth packing layer (164), a fifth packing layer (165), and a sixth packing layer (166); A liquid collector (17) is provided between the first packing layer (161) and the second packing layer (162), between the second packing layer (162) and the third packing layer (163), between the third packing layer (163) and the fourth packing layer (164), and between the fourth packing layer (164) and the fifth packing layer (165), respectively; A liquid distributor (18) is provided between the first packing layer (161) and the second packing layer (162), between the second packing layer (162) and the third packing layer (163), between the third packing layer (163) and the fourth packing layer (164), and between the fourth packing layer (164) and the fifth packing layer (165), respectively; between adjacent packing layers (16), the liquid collector (17) is located above the liquid distributor (18); the packing layer (16) uses BHS II type packing; The absorption tower (1) is further provided with an absorption liquid inlet (15) for inputting absorption liquid, and in the vertical direction, the exhaust gas inlet (13) is located below the sixth packing layer (166), and the absorption liquid inlet (15) is located between the fifth packing layer (165) and the sixth packing layer (166); Two bottom liquid circulation inlets (12) are provided; along the vertical direction, the bottom liquid circulation inlets (12) are arranged on the upper and lower sides of the first packing layer (161) respectively; The gas circulation unit (3) comprises: a fourth pipeline (32) connected to the inlet of the induced draft fan (31) and the gas outlet (14), a fifth pipeline (33) connected to the outlet of the induced draft fan (31) and the exhaust gas inlet (13), and a second control pipeline (34) connected to the outlet of the induced draft fan (31) and the outside; The waste gas is waste gas containing acid gas, and the waste gas is acid gas generated when slag is discharged from the slag discharge port of the distillation operation process and acid gas generated when carbon powder is unloaded from the filter chamber; the absorption liquid is a sodium hydroxide aqueous solution or a sodium acetate aqueous solution; the waste gas is input into the absorption tower (1) from the waste gas inlet (13), and the waste gas contacts with the alkaline absorption liquid input from the absorption liquid inlet (15) from bottom to top to undergo acid-base neutralization reaction and is absorbed at the same time to form purified waste gas at the upper part of the absorption tower (1), and the induced draft fan (31) provides suction force to allow the purified waste gas to enter the gas circulation unit (3), and when the online pH meter monitors that the pH is 7 and is qualified, the qualified gas is discharged, and if it is unqualified, the purified waste gas is recycled back to the absorption tower (1); The tower bottom liquid circulation unit (2) comprises: a pump body (21), a first pipeline (22) connected to the pump body (21) inlet and the tower bottom liquid outlet (11), a first control pipeline (23) connected to the pump body (21) outlet, a second pipeline (24) connected to the first control pipeline (23) and the tower bottom liquid circulation inlet (12), and a third pipeline (25) connected to the first control pipeline (23) and the outside; The control device further comprises: a control device; the control device is used to monitor the bottom liquid index in the bottom liquid circulation unit (2) and control the first control pipeline (23); the control device monitors whether the bottom liquid index meets the requirements for purifying the exhaust gas; if so, the control device controls the first control pipeline (23) to keep the second pipeline (24) connected to the pump body (21); otherwise, the control device controls the first control pipeline (23) to connect the third pipeline (25) to the pump body (21) to discharge the bottom liquid, and opens the absorption liquid inlet (15) to add fresh absorption liquid from the outside to ensure that the pH value of the absorption liquid in the tower is alkaline; in the step of discharging the bottom liquid, the tower liquid level is controlled at 20-60%, and the bottom liquid is tested. When the pH value of the absorption liquid in the tower is ≤11, the bottom liquid can be discharged. If the bottom liquid meets the requirements and has a neutral pH, it is fed into a sewage treatment device; otherwise, the bottom liquid is fed into a sedimentation tank containing some weakly acidic sewage for collection, sedimentation, neutralization treatment, and then sent to the sewage treatment device; The control device further comprises: a regulating valve for monitoring gas indicators in the pipeline of the gas circulation unit (3) and controlling the second control pipeline (34), and for controlling the absorption liquid inlet (15) of the absorption tower (1).

2. The exhaust gas treatment device according to claim 1, characterized in that: In the vertical direction, a demister (19) is also provided inside the absorption tower (1), and the demister (19) is located above the packing layer (16), the liquid collector (17) and the liquid distributor (18).

3. The exhaust gas treatment device according to claim 2, characterized in that: The demister (19) is a wire mesh demister.

4. A method for treating waste gas using the waste gas treatment device according to any one of claims 1 to 3, comprising the following steps: S1. introducing the waste gas to be treated from the outside through the waste gas inlet (13) on the absorption tower (1), and introducing the fresh absorption liquid from the outside through the absorption liquid inlet (15) on the absorption tower (1); S2. The bottom liquid circulation unit (2) and the gas circulation unit (3) are started respectively, and when the amount of fresh absorption liquid introduced into the absorption tower (1) reaches a preset requirement, the absorption liquid inlet (15) is closed; S3. The bottom liquid circulation unit (2) pumps the bottom liquid to the upper end of the absorption tower (1), and the bottom liquid flows from top to bottom and contacts the exhaust gas flowing from bottom to top; S4. The waste gas enters the gas circulation unit (3) through the gas outlet (14), and the control device monitors whether the indicators of the waste gas meet the standards. If so, the second control pipeline (34) is opened and the waste gas is discharged to the outside. Otherwise, the second control pipeline (34) remains closed and the waste gas is re-input into the absorption tower (1) through the fifth pipeline (33); S5. The control device monitors whether the index of the tower bottom liquid meets the requirements for purifying the exhaust gas. If so, the control device controls the first control pipeline (23) to keep the second pipeline (24) connected to the pump body (21). Otherwise, the control device controls the first control pipeline (23) to connect the third pipeline (25) to the pump body (21) to discharge the tower bottom liquid, and opens the absorption liquid inlet (15) to replenish fresh absorption liquid from the outside. In step S5, in the step of discharging the bottom liquid, the bottom liquid is tested, and if the bottom liquid is qualified, it is input into a sewage treatment device, otherwise, the bottom liquid is input into a sedimentation tank for collection and treatment, and finally sent to a sewage treatment device.

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