Device and method for separating chlorine from fumed silica tail gas

Abstract

The invention discloses a device and a method for separating chlorine from gas-phase white carbon black tail gas. The device comprises a fan, a plate type washing tower, an acid absorption tower, a membrane separation device and an alkali absorption tower group, the fan is used for sequentially conveying tail gas into the devices for circulation; the plate type washing tower is used for washing white carbon black in tail gas; the acid absorption tower is used for absorbing hydrogen chloride gas in the tail gas; chlorine and carbon dioxide mixed air in the tail gas can be separated through the membrane separation device; the alkali absorption tower group can respectively absorb chlorine to form a sodium hypochlorite solution and absorb the rest of mixed air to be discharged after reaching the standard, the device and the method for separating chlorine from the gas-phase white carbon black tail gas are provided, hydrogen chloride and chlorine in the tail gas generated in production of white carbon black from methyl trichlorosilane are separated, the tail gas is discharged after reaching the standard, and the production cost is reduced. The sewage generation amount is extremely small, and the sewage treatment cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas treatment, and in particular to a device and method for separating chlorine from gas-phase white carbon black tail gas. BACKGROUND

[0002] Gas-phase white carbon black is a widely used nanoscale powder material, and its production process is to use chlorosilane (monomethyltrichlorosilane or silicon tetrachloride) to produce nanoscale silicon dioxide powder through high-temperature hydrolysis by hydrogen-oxygen flame.

[0003] The chemical reaction carried out in the reaction furnace is as follows: Main reaction: CH3SiCl3(g) + 3O2(g) + 2H2(g) → SiO2(g) + 3HCl(g) + CO2(g) + 2H2O(g) Or SiCl4(g) + 2H2(g) + O2(g) = SiO2(s) + 4HCl(g); Side reaction: 4HCl(g) + O2(g) = 2H2O(g) + 2Cl2(g); Since this production process uses chlorosilane, hydrogen, and air as raw materials, a part of tail gas will be generated after the synthesis of gas-phase white carbon black, which mainly consists of carbon dioxide, nitrogen, oxygen, water vapor, hydrogen chloride, and chlorine, among which hydrogen chloride gas and chlorine are toxic and harmful gases and cannot be directly discharged.

[0004] There are multiple-stage tail gas absorption towers in the gas-phase white carbon black production device for treating chlorine and hydrogen chloride gas in the gas-phase white carbon black tail gas. When producing gas-phase white carbon black with silicon tetrachloride as raw material, the tail gas does not contain a large amount of carbon dioxide, and after acid absorption, the hydrogen chloride gas generates hydrochloric acid for sale, and after alkali absorption, the chlorine generates sodium hypochlorite with a concentration greater than 5% for sale. However, when producing gas-phase white carbon black with monomethyltrichlorosilane, the tail gas contains a large amount of carbon dioxide, and after acid absorption, the hydrogen chloride gas generates hydrochloric acid for sale, and after alkali absorption, the carbon dioxide and chlorine, because carbon dioxide participates in the reaction to generate sodium carbonate, make the generated sodium hypochlorite concentration less than 2%, which cannot meet the sales index and cannot be sold. The traditional method uses catalysts or hydrogen peroxide to react with low-concentration sodium hypochlorite solution to generate sodium chloride and oxygen, and then the wastewater containing sodium chloride and sodium carbonate is removed through a multiple-effect evaporation process, and the wastewater is sent to a wastewater treatment station.

[0005] The tail gas absorption method of traditional gas-phase white carbon black has the following problems when monomethyltrichlorosilane is used as raw material for production. 1. After tail gas absorption, carbon dioxide is also absorbed by lye, resulting in a low concentration of sodium hypochlorite solution formed after absorption of chlorine by lye, which cannot be sold; 2. The concentration of sodium hypochlorite solution formed after tail gas absorption is relatively low, and it needs to undergo catalytic treatment before entering multi-effect evaporation for desalination. The wastewater is sent to the sewage treatment station, which generates a lot of wastewater, high energy consumption, poor economic benefits, and great environmental pressure. Summary of the Invention

[0006] The present invention addresses the deficiencies in the prior art and provides a device and method for separating chlorine from gaseous silica tail gas. The device separates hydrogen chloride and chlorine from the tail gas produced by producing silica from monomethyltrichlorosilane, so that the tail gas meets emission standards, generates very little sewage, and greatly reduces sewage treatment costs.

[0007] To solve the above technical problems, the present invention is solved by the following technical solutions: a device for separating chlorine from gaseous silica tail gas, comprising a plate scrubber, an acid absorption tower, a membrane separation device and an alkali absorption tower group; The inlet of the plate-type scrubber is used to communicate with the tail gas; The plate-type washing tower is used to wash white carbon black in the tail gas; The acid absorption tower is used to absorb hydrogen chloride gas in the tail gas; The tail gas can be separated into chlorine and carbon dioxide mixed with air in the tail gas by passing through a membrane separation device; The alkali absorption tower group can absorb chlorine to form sodium hypochlorite solution, and absorb the remaining mixed air and then discharge it in compliance with the standards.

[0008] In the above solution, preferably, a plurality of inclined plates are provided in the plate-type washing tower, and the inclined plates have an inclination angle of 45°.

[0009] In the above scheme, preferably, dilute hydrochloric acid or water is passed through the acid absorption tower.

[0010] In the above solution, preferably, the membrane separation device includes a separation cylinder and a membrane group arranged in the center of the separation cylinder; The separation cylinder is provided with an air inlet at one end and an air outlet and a discharge pipe at the other end; The air inlet is connected to the acid absorption tower.

[0011] In the above solution, preferably, both ends of the separation cylinder are rotatably connected to the air inlet pipe and the three-way valve, and a separation chamber is provided between the wall of the separation cylinder and the membrane group; A plurality of exhaust holes are provided on the wall of the separation cylinder, and the exhaust holes are connected to the discharge pipe.

[0012] In the above solution, preferably, the separation cylinder is provided with an exhaust ring that matches the exhaust hole, the exhaust ring is provided with an exhaust groove, and the exhaust ring is provided with a discharge pipe that passes through the exhaust groove.

[0013] In the above scheme, preferably, the air inlet pipe and the three-way valve are fixed on the external frame, the separation cylinder is fixed with a transmission gear, the external frame is fixed with a drive motor, and the output shaft end of the drive motor is fixed with a drive gear meshing with the transmission gear.

[0014] In the above solution, preferably, the alkali absorption tower group includes a first alkali tower connected to the gas outlet and a second alkali tower connected to the discharge pipe, and sodium hydroxide solution is passed through the first alkali tower.

[0015] In the above scheme, preferably, a method for separating chlorine from fumed silica tail gas is used, and the method is as follows: S1: The gas phase silica tail gas is passed into the lower part of the plate scrubber, 30-32% concentration of hydrochloric acid is added from the upper part of the plate scrubber, and then circulated by pumping to remove a small amount of silica in the tail gas; S2: The tail gas from the top of the plate scrubber is introduced into the lower middle part of the acid absorption tower. 19-20% dilute hydrochloric acid or water enters from the upper part of the acid absorption tower to absorb the hydrogen chloride gas in the tail gas. The acid absorption tower pumps the gas back to the middle part of the acid absorption tower to circulate and absorb the hydrogen chloride gas. S3: The tail gas from the acid absorption tower is passed into the membrane separation device; The separated chlorine enters the first alkali tower, and the separated carbon dioxide mixed with air enters the second alkali tower for purification. The small amount of alkaline wastewater generated is sent to the sewage treatment station. The separated chlorine enters the lower middle part of the first alkali tower, and enters 16-18% sodium hydroxide solution from the upper part of the first alkali tower to absorb the chlorine. The alkali tower pump pumps the chlorine back to the middle part of the tower to circulate and absorb the chlorine gas. There are two sections of packing inside the alkali tower, and the circulating liquid contacts the chlorine gas in the packing layer of the alkali tower; after the concentration of the sodium hypochlorite solution reaches 6-8%, it is sent to the sodium hypochlorite solution storage tank.

[0016] In the above scheme, preferably, in step S2, there are two sections of packing inside the acid absorption tower, and the circulating liquid contacts the hydrogen chloride gas and liquid in the packing layer of the acid absorption tower, the temperature is controlled at 20-30°C, and the acid concentration reaches 30-32% before being sent to the hydrochloric acid storage tank.

[0017] The beneficial effects of the present invention are as follows: the present invention provides a device and method for separating chlorine from gaseous silica tail gas, wherein hydrogen chloride and chlorine in the tail gas of silica produced by monomethyltrichlorosilane are separated, the tail gas is discharged in compliance with standards, the hydrogen chloride is absorbed with water or dilute acid to form 30-32% hydrochloric acid, meeting the standards of industrial hydrochloric acid, the separated chlorine is absorbed with alkali liquor to form a sodium hypochlorite solution of more than 5%, meeting the standards of sodium hypochlorite solution, and then sold, a very small amount of chlorine is absorbed with alkali liquor and then treated with sewage, the amount of sewage generated is extremely small, and the sewage treatment cost is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention provides a schematic structural diagram of a device for separating chlorine from gaseous silica tail gas.

[0019] Figure 2 Schematic diagram of the membrane separation device of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1-Figure 2 .

[0021] A device for separating chlorine from fumed silica tail gas comprises a blower 1, a plate scrubber 2, an acid absorption tower 3, a membrane separation device 4, and an alkali absorption tower group 5. The blower 1 is used to sequentially convey the tail gas to each of the above devices for circulation. Specifically, the blower 1 first conveys the tail gas containing hydrogen chloride gas, chlorine, carbon dioxide, water vapor, and air to the plate scrubber 2.

[0022] The plate washing tower 2 is connected to the acid absorption tower 3 through a pipeline. The tail gas discharged from the acid absorption tower 3 is connected to the membrane separation device 4 through a pipeline. The membrane separation device 4 includes an outlet 404 and a discharge pipe 902. The outlet pipe 404 is connected to the first alkali tower 501 through a pipeline. The discharge pipe 902 is connected to the second alkali tower 502 through a pipeline.

[0023] The plate scrubber 2 is used to scrub white carbon black from the tail gas. Several inclined plates 201 are provided in the plate scrubber 2. The inclined plates 201 are inclined at a 45° angle. Hydrochloric acid with a concentration of 30-32% is added to the top of the plate scrubber 2 and then circulated by a pump for scrubbing to remove a small amount of white carbon black from the tail gas. The provision of the inclined plates 201 prevents the washed white carbon black from being deposited on the plates. After scrubbing, the gas enters the acid absorption tower 3, which is used to absorb hydrogen chloride gas in the tail gas.

[0024] Dilute hydrochloric acid or water is passed through the acid absorption tower 3. After the mixed gas containing hydrogen chloride gas enters the acid absorption tower 3, the hydrogen chloride gas in the tail gas is absorbed and eventually absorbed into 30-32% hydrochloric acid for sale. After the gas is absorbed by the acid absorption tower 3, the remaining mixed gas containing carbon dioxide, chlorine, and air enters the membrane separation device 4 for separation. The membrane separation device 4 can separate the mixed gas into two discharge paths, one path is chlorine, and the other path is a mixed gas of carbon dioxide and air.

[0025] The two gases separated by the membrane separation device 4 enter the alkali absorption tower group 5 for absorption. Specifically, the alkali absorption tower group 5 can absorb chlorine to form sodium hypochlorite solution and absorb the remaining mixed air before discharge in compliance with standards. The alkali absorption tower group 5 includes a first alkali tower 501 and a second alkali tower 502. Sodium hydroxide solution is passed through the first alkali tower 501. The chlorine gas passing through the membrane separation device 4 enters the first alkali tower 501 for absorption. 16-18% sodium hydroxide solution is passed through the first alkali tower 501, so that the chlorine gas and the sodium hydroxide solution are absorbed and mixed to form sodium hypochlorite solution. Finally, after the solution concentration reaches 6-8%, it is sent to the sodium hypochlorite solution storage tank.

[0026] The second alkali tower 502 is used to absorb the second gas separated by the membrane separation device 4, that is, the mixed gas of carbon dioxide and air. After entering the second alkali tower 502, it is absorbed and mixed with the alkali liquid inside to form alkaline wastewater for discharge, so that it can achieve standard discharge.

[0027] In this embodiment, when the membrane separation device 4 separates a mixed gas containing carbon dioxide, chlorine, and a small amount of air, if the carbon dioxide content is high, the separation speed of carbon dioxide when penetrating the membrane is not fast enough. Therefore, carbon dioxide is easily mixed with the chlorine and enters the chlorine channel. As a result, after the chlorine passes into the first alkali tower 501, carbonate alkali impurities (such as sodium carbonate) are generated. This affects the quality of the subsequent sodium hypochlorite solution. Therefore, the membrane separation device 4 needs to be further improved to improve its separation efficiency and separation quality.

[0028] The membrane separation device 4 adopts a cross-flow separation method, that is, the mixed gas flows parallel to the membrane surface, carbon dioxide passes through the membrane, and chlorine continues to flow along the membrane surface. This is the existing technology of the cross-flow separation method in membrane separation and will not be described in detail here.

[0029] like Figure 2 As shown, the membrane separation device 4 includes a separation cylinder 401 and a membrane group 402 arranged at the center of the separation cylinder 401. The separation cylinder 401 is provided with an air inlet 403 at one end and an air outlet 404 at the other end. A separation chamber 405 is provided between the cylinder wall of the separation cylinder 401 and the membrane group 402. After the mixed gas enters the membrane group 402 through the air inlet 403, the chlorine flows horizontally to the right along the membrane group 402 and is discharged at the air outlet 404. The carbon dioxide radially penetrates the membrane group 402 during the process of flowing to the right along the membrane group 402 and enters the separation chamber 405. A plurality of exhaust holes 406 are provided on the cylinder wall of the separation cylinder 401. The carbon dioxide bombs entering the separation chamber 405 are discharged through the exhaust holes 406, thereby achieving separation of the mixed gas.

[0030] The separation cylinder 401 is connected with the air inlet pipe 6 and the three-way valve 7 at two ends respectively, and the air inlet pipe 6 and the three-way valve 7 are fixed on the external frame, and the two ends of the separation cylinder 401 are rotatably arranged on the air inlet pipe 6 and the three-way valve 7, and a rotating sealing structure is arranged between the separation cylinder 401 and the air inlet pipe 6, so that the mixed gas in the air inlet pipe 6 can be sealed into the air inlet 403 while the separation cylinder 401 rotates.

[0031] The driving gear 801 is arranged on the output shaft end of the driving motor 8, and the driving motor 8 is a servo motor, which transmits power to the transmission gear 407 to rotate the separation cylinder 401 relative to the air inlet pipe 6, and after the separation cylinder 401 rotates, the carbon dioxide entering the membrane group 402 generates centrifugal force by the rotation of the separation cylinder 401, accelerates the radial penetration of the membrane group 402, and quickly enters the separation cavity 405, prevents the carbon dioxide from accumulating on the surface of the membrane group 402 and being difficult to be quickly removed, and affects the separation efficiency of the membrane group 402, and by increasing the rotating speed of the separation cylinder 401, the separation speed of the carbon dioxide can be increased.

[0032] The external frame is provided with an exhaust ring 9 matched with the exhaust hole 406, the exhaust ring 9 is sleeved on the separation cylinder 401, and a Y-shaped sealing ring is arranged between the exhaust ring 9 and the outer wall of the separation cylinder 401, and the inner wall of the exhaust ring 9 is provided with an exhaust groove 901 matched with the exhaust hole 406, the exhaust ring 9 is provided with an exhaust pipe 902 penetrating the exhaust groove 901, and the exhaust pipe 902 is connected with the second alkali tower 502, so that the separated carbon dioxide gas is introduced into the second alkali tower 502 for absorption treatment.

[0033] The three-way valve 7 is an electromagnetic three-way valve, which includes a first valve pipe 701 connected with the air outlet 404 of the separation cylinder 401, and a second valve pipe 703 and a third valve pipe 704 connected with the first valve pipe 701 through a valve core 702, and the valve core 702 can be "L-shaped" or "T-shaped", which is a prior art of the three-way valve, and will not be described in detail here.

[0034] When the first valve pipe 701 and the second valve pipe 703 are communicated, the chlorine gas separated by the membrane separation device 4 is discharged through the second valve pipe 703 and enters the first alkali tower 501 for treatment; after rotating the valve core 702, the first valve pipe 701 and the third valve pipe 704 are communicated, at this time, the chlorine gas is discharged through the third valve pipe 704.

[0035] The third valve tube 704 is connected to the detection unit 10, which includes a detection box 11. A detection membrane 12 is provided in the detection box 11. The detection membrane 12 is arranged across the middle of the detection box 11. The upper end of the detection box 11 is connected to the third valve tube 704, and the lower end is provided with a discharge port 13. The detection membrane 12 is also a separation membrane, which adopts a dead-end flow separation method. That is, when chlorine enters the detection box 11 through the third valve tube 704, the chlorine contacts the detection membrane 12 perpendicularly. Then, the carbon dioxide mixed in the chlorine vertically penetrates the membrane surface and enters the box below. The chlorine flows parallel to the membrane and is discharged to the secondary port 14 on the right side of the detection box 11. The secondary port 14 is connected to the first alkali tower 501, so that the detected chlorine is discharged into the first alkali tower 501 for treatment.

[0036] A detector 15 is provided below the detection box 11. The detector 15 is a carbon dioxide concentration detector. The detector 15 is connected to the drive motor 8 through a controller. The detector 15 is located below the detection membrane 12. The carbon dioxide gas passing through the detection membrane 12 enters the detection range of the detector 15, so that the carbon dioxide concentration passing through the detection membrane 12 is measured by the detector 15 and fed back to the controller. Then, the controller controls the speed of the drive motor 8 according to the carbon dioxide concentration. The higher the carbon dioxide concentration detected by the controller, the faster the drive motor 8 drives the separation cylinder 401 to rotate, thereby increasing the centrifugal force of the carbon dioxide passing through the membrane group 402 and increasing its flow speed to the separation chamber 405; the detected carbon dioxide enters the second alkali tower 502 through the discharge port 13 for treatment.

[0037] Under normal conditions, the first valve tube 701 and the second valve tube 703 on the three-way valve 7 are in a connected state, thereby performing batch processing on the separated gas. When testing is required, the three-way valve 7 is opened at a fixed time, the valve core 702 is rotated, and the first valve tube 701 and the third valve tube 704 are connected. At this time, chlorine mixed with a certain amount of carbon dioxide enters the detection box 11 and is separated by a dead-end flow separation method. After the gas encounters the detection membrane 12, the carbon dioxide passes through the membrane and enters the detection box below, so that the detector 15 detects the carbon dioxide content, and the chlorine is discharged to the secondary port 14 arranged parallel to the detection membrane 12.

[0038] Because the dead-end flow separation method has a very high separation ability, the detection membrane 12 is prone to clogging. Therefore, in this embodiment, a continuously drivable detection membrane is provided. Specifically, a membrane roll 121 is rotatably provided on the outer wall of one side of the detection box 11, and a collection roll 122 is rotatably provided on the other side. The membrane roll 121 passes one end of the detection membrane 12 across the detection box 11 and is fixed to the collection roll 122 on the other side. When the collection roll 122 rotates, the new detection membrane 12 can be pulled from left to right to replace the old membrane.

[0039] The collecting roll 122 includes a reel 123, a one-way bearing 124 is provided between the reel 123 and the collecting roll 122, a rotating rod 125 is provided on the valve core 702 for driving the valve core 702 to rotate, and a synchronous wheel 126 is provided on the rotating rod 125, and the reel 123 is connected to the synchronous wheel 126 through a synchronous belt 127, so that after the valve core 702 rotates once, the reel 123 is driven to rotate, and the collecting roll 122 is further rotated by a certain angle through the one-way bearing 124, and the used detection film 12 placed in the detection box 11 is pulled out and replaced with a new detection film 12, that is, the three-way valve 7 is opened once, and the detection film 12 can be replaced once. When the valve core 702 of the three-way valve 7 is reset, the collecting roll 122 is in a stationary state due to the action of the one-way bearing 124, and the reel 123 rotates a certain angle relative to the collecting roll 122 to reset.

[0040] In this embodiment, the chlorine gas discharged from the gas outlet 404 can be checked regularly or at fixed times by the detection unit 10. By checking the composition of the carbon dioxide therein, the rotation speed of the separation barrel 401 can be adjusted in time to adapt it to the concentration of carbon dioxide in the separation barrel 401, and separation can be performed in time to prevent it from adhering to the membrane group 402 and affecting the separation speed and separation quality of the mixed gas.

[0041] A method for separating chlorine from fumed silica tail gas, the method is as follows: S1: The fumed silica production tail gas containing hydrogen chloride, chlorine, carbon dioxide, air and a small amount of silica is introduced into the lower middle part of a plate-type scrubber 2 through a blower 1. 30-32% hydrochloric acid is added from the upper part of the plate-type scrubber 2, and then circulated by a pump to remove a small amount of silica in the tail gas. The plate-type scrubber 2 is provided with inclined plates at an angle of 45 degrees to prevent the washed silica from being deposited on the plates. S2: The tail gas from the top of the plate scrubber 2 is passed into the lower middle part of the acid absorption tower 3. 19-20% dilute hydrochloric acid or water enters the upper part of the acid absorption tower 3 to absorb the hydrogen chloride gas in the tail gas. The acid absorption tower 3 pumps back to the middle part of the acid absorption tower 3 to circulate and absorb the hydrogen chloride gas. There are two sections of packing inside the acid absorption tower 3. The circulating liquid contacts the hydrogen chloride gas and liquid in the packing layer of the acid absorption tower 3. The temperature is controlled at 20-30°C, the flow rate of dilute hydrochloric acid is controlled at 1.5m³ / h, and the flow rate of circulating liquid is controlled at 30m³ / h. After the acid concentration reaches 30-32%, it is sent to the hydrochloric acid storage tank. S3: The tail gas from the acid absorption tower 3 is passed into the membrane separation device 4. The different sizes of chlorine and carbon dioxide molecules are used to effectively separate them in the membrane, thereby separating the chlorine and carbon dioxide mixed air; S4: In S4, the separated chlorine enters the first alkali tower 501, the separated carbon dioxide and air enter the second alkali tower 502 for purification, and a small amount of alkaline wastewater produced is discharged to the wastewater treatment station; S5: In S4, the separated chlorine enters the lower part of the first alkali tower 501, 16-18% sodium hydroxide solution enters the upper part of the first alkali tower 501 to absorb chlorine, the alkali tower is pumped back to the middle part of the tower to circulate and absorb chlorine gas, and there are two sections of fillers in the alkali tower. The circulating liquid contacts chlorine gas and liquid in the filler layer of the alkali tower; the flow rate of the sodium hydroxide solution is controlled at 0.8 m³ / h, the flow rate of the circulating liquid is controlled at 20 m³ / h, and the concentration of the sodium hypochlorite solution reaches 6-8% before being sent to the sodium hypochlorite solution storage tank.

[0042] The fan, the acid absorption tower, the membrane separation device and the alkali absorption tower group in the embodiment form a tail gas absorption system, hydrogen chloride gas in the gas phase carbon black tail gas is absorbed to form hydrochloric acid for sale or to enter a hydrochloric acid analysis system of trichlorosilane for analysis, and dilute hydrochloric acid is returned to the acid absorption tower for absorption. The membrane separation device is used to separate chlorine and carbon dioxide, the separated chlorine is absorbed by alkali to form 6-8% sodium hypochlorite solution for sale. The tail gas meets the discharge standard. The method in the embodiment separates and recovers chlorine in the gas phase carbon black tail gas produced by monomethyl chlorosilane, and no large amount of wastewater is generated.

[0043] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A device for separating chlorine from fumed silica tail gas, characterized by: It includes a plate-type washing tower (2), an acid absorption tower (3), a membrane separation device (4) and an alkali absorption tower group (5); The inlet of the plate-type scrubber (2) is used to communicate with the tail gas; The plate-type washing tower (2) is used to wash white carbon black in the tail gas; The acid absorption tower (3) is used to absorb hydrogen chloride gas in the tail gas; The tail gas passes through a membrane separation device (4) to separate the chlorine and carbon dioxide mixed with air in the tail gas; The alkali absorption tower group (5) can absorb the chlorine gas to form a sodium hypochlorite solution, and absorb the remaining mixed air to meet the discharge standards.

2. The device for separating chlorine from fumed silica tail gas according to claim 1, characterized in that: A plurality of inclined plates (201) are provided in the plate-type washing tower (2), and the inclined plates (201) have an inclination angle of 45°.

3. The device for separating chlorine from fumed silica tail gas according to claim 1, characterized in that: Dilute hydrochloric acid or water is passed through the acid absorption tower (3).

4. The device for separating chlorine from fumed silica tail gas according to claim 1, characterized in that: The membrane separation device (4) comprises a separation cylinder (401) and a membrane group (402) arranged at the center of the separation cylinder (401); The separation cylinder (401) is provided with an air inlet (403) at one end and an air outlet (404) and a discharge pipe (902) at the other end; The air inlet (403) is connected to the acid absorption tower (3).

5. The device for separating chlorine from fumed silica tail gas according to claim 4, characterized in that: The two ends of the separation cylinder (401) are rotatably connected to the air inlet pipe (6) and the three-way valve (7), and a separation chamber (405) is provided between the cylinder wall of the separation cylinder (401) and the membrane group (402); A plurality of exhaust holes (406) are provided on the wall of the separation cylinder (401), and the exhaust holes (406) are connected to the discharge pipe (902).

6. The device for separating chlorine from fumed silica tail gas according to claim 5, characterized in that: The separation cylinder (401) is sleeved with an exhaust ring (9) that matches the exhaust hole (406), an exhaust groove (901) is provided in the exhaust ring (9), and a discharge pipe (902) that is connected to the exhaust groove (901) is provided on the exhaust ring (9).

7. The device for separating chlorine from fumed silica tail gas according to claim 5, characterized in that: The air inlet pipe (6) and the three-way valve (7) are fixed on the external frame, the separation cylinder (401) is fixedly provided with a transmission gear (407), and the external frame is fixedly provided with a drive motor (8), and the output shaft end of the drive motor (8) is fixedly provided with a drive gear 801 that meshes with the transmission gear (407).

8. The device for separating chlorine from fumed silica tail gas according to claim 4, characterized in that: The alkali absorption tower group (5) comprises a first alkali tower (501) connected to the gas outlet (404) and a second alkali tower (502) connected to the discharge pipe (902), wherein a sodium hydroxide solution flows into the first alkali tower (501).

9. A method for separating chlorine using the device for separating chlorine from fumed silica tail gas as claimed in claim 8, characterized in that: The method is as follows: S1: The gas phase silica tail gas is introduced into the lower middle part of the plate washing tower (2), 30-32% concentration hydrochloric acid is added from the upper part of the plate washing tower (2), and then circulated by pumping to remove a small amount of silica in the tail gas; S2: The tail gas from the top of the plate scrubber (2) is introduced into the middle and lower part of the acid absorption tower (3), and 19-20% dilute hydrochloric acid or water enters from the upper part of the acid absorption tower (3) to absorb the hydrogen chloride gas in the tail gas. The acid absorption tower (3) pumps the gas back to the middle part of the acid absorption tower (3) to circulate and absorb the hydrogen chloride gas; S3: passing the tail gas from the acid absorption tower (3) into the membrane separation device (4); The separated chlorine enters the first alkali tower (501), and the separated carbon dioxide mixed with air enters the second alkali tower (502) for purification. The small amount of alkaline wastewater generated is sent to the sewage treatment station; The separated chlorine enters the lower middle part of the first alkali tower (501), and enters the 16-18% sodium hydroxide solution from the upper part of the first alkali tower (501) to absorb the chlorine. The alkali tower pump pumps the chlorine back to the middle part of the tower to circulate and absorb the chlorine gas. There are two sections of packing inside the alkali tower, and the circulating liquid contacts the chlorine gas in the packing layer of the alkali tower. After the concentration of the sodium hypochlorite solution reaches 6-8%, it is sent to the sodium hypochlorite solution storage tank.

10. A method for separating chlorine from fumed silica tail gas according to claim 9, characterized in that: In step S2, there are two sections of packing inside the acid absorption tower (3). The circulating liquid contacts the hydrogen chloride gas and liquid in the packing layer of the acid absorption tower (3). The temperature is controlled at 20-30°C. After the acid concentration reaches 30-32%, it is sent to the hydrochloric acid storage tank.

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