Phosgenation tail gas alkali destruction device and phosgenation tail gas alkali destruction method

Abstract

The invention belongs to the technical field of phosgenation reaction tail gas treatment, and particularly relates to a phosgenation tail gas alkali destruction device and a method thereof.The method comprises the following steps that an operator introduces tail gas into a falling film absorber, the falling film absorber absorbs hydrochloric acid in the tail gas, and first treatment gas is obtained; introducing the treated gas I into a catalytic hydrolysis tank, and destroying phosgene in the treated gas I by adopting a catalytic hydrolysis method to obtain treated gas II; the second treatment gas is introduced into a multi-stage alkali destroying tower, a 1%-10% dilute alkali solution is conveyed to the top of the alkali destroying tower through a conveying pump, and an inorganic salt solution and a third treatment gas are generated through an acid-base reaction; the inorganic salt solution is sent to a high-salinity wastewater treatment device for treatment, third treatment gas is sent to an incineration device for treatment, combustible gas such as unreacted carbon monoxide and organic matter is removed, and final gas is obtained and discharged to the outside. According to the scheme, the problem of waste caused by more generated high-salinity wastewater is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of phosgenation reaction tail gas treatment, and specifically relates to a phosgenation tail gas alkali destruction device and a method thereof. Background Art

[0002] Phosgene is an important raw material for chemical production, with a domestic production capacity of 1.5 million tons (1.16 million tons in 2008). It is widely used in industrial production such as pesticides, medicines, fuels, and polyurethanes, and has attracted much attention due to its high toxicity. In the chemical production process using phosgene as a raw material, phosgene tail gas containing phosgene will be generated. Due to different process control requirements in the production process, the content of phosgene tail gas generated is also different, generally between 10% and 50% (V / V). Phosgene tail gas needs to be treated before discharge to reduce pollution to the environment.

[0003] At present, there is a method for treating phosgenation reaction tail gas on the market with application number 201911412500.5, which comprises the following steps: passing the light reaction tail gas into a spray absorption tower with solvent A as absorbent, absorbing chlorine in the tail gas in the liquid phase, and desorbing the saturated solvent A to obtain separated chlorine; passing the remaining tail gas into a condensation tower to recover the organic solvent in the tail gas; passing the remaining tail gas into a spray absorption tower with solvent B as absorbent, absorbing hydrogen chloride in the tail gas in the liquid phase, and desorbing the saturated solvent B to obtain separated hydrogen chloride gas; passing the remaining tail gas into a spray absorption tower with catalyst C as absorbent, and hydrolyzing it into hydrogen chloride and carbon dioxide gas on the wetted catalyst surface; the present invention first absorbs the chlorine in the tail gas, then treats the organic solvent in the tail gas to avoid affecting the use of the catalyst, then treats the hydrogen chloride in the tail gas, and finally treats the phosgene, which has a good treatment effect on the tail gas.

[0004] But there is also a problem: this solution produces a lot of high-salt wastewater, resulting in waste.

[0005] At present, a light tail gas treatment device with announcement number CN211799878U on the market includes a hydrochloric acid absorption tower, a phosgene hydrolysis tower, a phosgene alkali washing tower and an alkali washing tank, wherein the upper ends of the hydrochloric acid absorption tower, the phosgene hydrolysis tower and the phosgene alkali washing tower are all connected with a demister, and the hydrochloric acid absorption tower, the phosgene hydrolysis tower and the phosgene alkali washing tower are all connected with a bed of fillers and a second bed of fillers through a filler support grid plate, and a first distributor is installed in the hydrochloric acid absorption tower below the demister. The light tail gas treatment device absorbs hydrogen chloride in the tail gas through the hydrochloric acid absorption tower, and then destroys the phosgene in the tail gas by the primary hydrolysis tower and the secondary hydrolysis tower, absorbs hydrogen chloride gas to become dilute hydrochloric acid, and the dilute hydrochloric acid is cooled by the hydrochloric acid absorption cooler and enters the hydrochloric acid absorption tower for countercurrent spraying, and finally makes qualified hydrochloric acid using waste gas to reduce costs, and after two-stage alkali washing in the alkali washing tower, the tail gas after alkali washing is discharged into the chimney through a fan to achieve pollution-free emission.

[0006] However, there are some problems: 1. The alkali washing tower of the device uses spraying for gas-liquid mixing, which is inefficient and slow in production. 2. If the gas-liquid mixing is done in the same way as the distillation tower, although the efficiency is high, it is easy to cause flooding. The existing method is to control the filter hole size of the tower plate to solve this problem. 3. Many inorganic salt particles are easily generated in the alkali washing tower, which are easy to clog the pipeline. The commonly used method is to filter with a filter screen, but the filter screen needs to be replaced every once in a while, and the alkali washing tower is not convenient to disassemble. Summary of the invention

[0007] The invention provides a phosgenation tail gas alkali destruction device and method thereof, which are used to solve the problem that the service life of a filter screen in an alkali destruction tower is short.

[0008] This solution provides a phosgenation tail gas alkali destruction device, including a catalytic hydrolysis box, an alkali destruction tower, a pH detector and a falling film absorber, wherein the falling film absorber, the catalytic hydrolysis box, the alkali destruction tower and the pH detector are connected in sequence;

[0009] The alkali destruction tower includes a cleaning mechanism. A tower plate is provided in the tower body. The cleaning mechanism includes an air intake plate, a filter plate and a cleaning brush. The air intake plate and the filter plate are fixedly connected at a certain angle. The air intake plate cooperates with the air inlet, and the filter plate cooperates with the liquid outlet. The connection between the air intake plate and the filter plate is rotatably connected to the tower body through a torque spring. The filter plate cooperates with the cleaning brush, and the cleaning brush is fixedly connected to the tower body.

[0010] The principle of this scheme is that the operator first passes the tail gas into the falling film absorber to remove the hydrochloric acid in the tail gas, and then passes the subsequent gas into the catalytic hydrolysis box to destroy the phosgene therein by catalytic hydrolysis. Then the subsequent gas is passed into the alkali destruction tower, and the gas is passed in from the air inlet. As the gas enters, the air inlet plate is pushed open, and at the same time, the filter plate is driven to rotate until the filter plate contacts and covers the liquid outlet, playing a role of filtering particles. At the same time, the liquid is passed in from the liquid inlet at the top of the tower, and the gas and liquid flow back and forth, increasing the contact area between the two, so that the reaction is maximized. The tower plate can slow down the falling speed of the liquid, so that the gas-liquid contact time is increased. When the tail gas treatment is completed, the device stops, and the air inlet plate returns to its original position under the action of the torque spring, and at the same time drives the filter plate to tilt, so that the filter plate contacts the brush needle of the cleaning brush, and the brush needle passes through the filter hole of the filter plate to clean the particles adhering to it, so that the staff does not need to dismantle the alkali destruction tower to replace the filter screen.

[0011] The gas in the alkali destruction tower, the carbon dioxide and hydrogen chloride therein react with sodium hydroxide to form inorganic salt solutions such as sodium carbonate, sodium chloride, and sodium bicarbonate. The PH value of the inorganic salt solution is tested by a PH detector, and it must reach the set value before it can be discharged. If it does not reach the set value, the staff needs to continue to send liquid into the alkali destruction tower to react and convert all harmful gases and carbon dioxide into dischargeable gases.

[0012] The beneficial effects of this solution are: 1. The device makes the gas and liquid fully contact by gas-liquid countercurrent, so that the reaction is more thorough and more efficient than the spray reaction. 2. The device prolongs the service life of the filter screen by the cleaning mechanism.

[0013] Furthermore, it also includes a liquid flooding prevention mechanism, which includes a connecting rod, a slide plate, a baffle plate and an insert plate. The tower plate is provided with a groove, the insert plate is slidably connected to the groove, the insert plate is fixedly connected to the slide plate, the baffle plate is fixedly connected to the tower body, the baffle plate is slidably connected to the slide plate, one end of the connecting rod is hinged to the slide plate, and the other end is hinged to the filter plate.

[0014] When the alkali destruction tower is flooded, the gas at the bottom cannot pass through the liquid above, which increases the pressure below and reduces the flow rate of the gas into the air inlet, causing the air inlet plate to slowly move back due to the action of the torque spring, and at the same time causing the filter plate to start moving, the filter plate drives the connecting rod to move, the connecting rod drives the slide plate to move, and the slide plate drives the insert plate to pull out. The insert plate is a thin plate with filter holes. Pulling out the insert plate makes the tower plate longer and the filter holes more, making it easier for the liquid to fall. At the same time, the gap between the downcomer plate and the slide plate becomes larger, allowing the liquid to have more space to pass through the gas, solving the problem of flooding. When the air pressure in the tower returns to normal, the air flow rate at the air inlet returns to normal, the air inlet plate is pushed to the limit position again, and the filter plate also covers the liquid outlet to filter out impurities.

[0015] Furthermore, it also includes a high-salt wastewater treatment device, and the liquid outlet is connected to the high-salt wastewater treatment device. The high-salt wastewater treatment device can effectively utilize the high-salt wastewater to prevent waste.

[0016] Furthermore, the invention also comprises an incineration device, and the gas outlet is connected to the incineration device. Some carbon monoxide and organic gas still remain in the gas, which can be removed by incineration.

[0017] Furthermore, the catalytic hydrolysis box includes a box body, a nozzle and a permeable membrane. The box body is provided with a water flow port, an air flow port and an exhaust port. The nozzle is connected to the water flow port. The permeable membrane is provided with a plurality of nozzles. The nozzle cooperates with the permeable membrane. The air flow port is aligned with the permeable membrane. The permeable membrane is provided with a catalyst. The water flow port starts to flow in. The nozzle is located between the two permeable membranes. The nozzle sprays water and sprinkles the water on the catalyst in the permeable membrane. When the gas enters from the air flow port, the gas will impact the permeable membrane and pass through the permeable membrane to contact the catalyst and react. This mechanism makes the catalytic reaction more thorough.

[0018] Furthermore, it also includes a phosgene detection device, one end of which is connected to the exhaust port, and the other end of which is connected to the air inlet. The phosgene detection device is provided with a reflux end, and the reflux end is connected to the air flow port.

[0019] The phosgene detection device can check whether the gas coming out of the catalytic hydrolysis box contains phosgene to prevent the phosgene from being not treated cleanly. If it contains phosgene, the phosgene will return to the gas flow outlet from the reflux end for catalytic hydrolysis again. If it does not contain phosgene, it will be directed to the alkali destruction tower from the other end.

[0020] Furthermore, the alkali destruction towers are provided with three, the first gas outlet of the first alkali destruction tower is connected to the gas inlet of the second alkali destruction tower, the second gas outlet of the second alkali destruction tower is connected to the third gas inlet of the third alkali destruction tower, the first liquid outlet of the first alkali destruction tower is connected to the liquid inlet of the second alkali destruction tower, the second liquid outlet of the second alkali destruction tower is connected to the third liquid inlet of the third alkali destruction tower, the third liquid outlet is connected to the high-salt wastewater treatment device, and the third gas outlet is connected to the incineration device. The three alkali destruction towers react layer by layer to make the reaction more thorough.

[0021] This scheme provides a method for phosgenation tail gas alkali destruction, comprising the following steps:

[0022] Step S10: passing the tail gas into a falling film absorber, and the falling film absorber absorbs the hydrochloric acid in the tail gas to obtain a treated gas 1;

[0023] Step S20: passing the treated gas 1 into a catalytic hydrolysis box to destroy the phosgene therein by catalytic hydrolysis to obtain treated gas 2;

[0024] Step S30: passing the treated gas 2 into a multi-stage alkali destruction tower, delivering a 1%-10% dilute alkali solution to the top of the alkali destruction tower through a delivery pump, and automatically introducing the alkali solution into an alkali wastewater tank after the alkali solution pH value drops to 7.5-10 after online monitoring, and then being delivered to a high-salt wastewater treatment device to generate an inorganic salt solution and treated gas 3 through an acid-base reaction;

[0025] Step S40: Send the inorganic salt solution to a high-salt wastewater treatment device for treatment, and send the treated gas to an incineration device for treatment to remove unreacted carbon monoxide and combustible gases such as organic matter to obtain the final gas, which is discharged to the outside.

[0026] This method greatly improves the exhaust gas treatment efficiency and also reduces the output of high-salt wastewater.

[0027] Furthermore, the dilute alkali solution in step S30 is a 3.5%-4% sodium hydroxide solution, which reacts more thoroughly with the tail gas.

[0028] Furthermore, the alkali solution is directly discharged after the online monitoring pH value of 7.5-7.8 in step S30. The wastewater discharge per ton of product of the whole company is reduced from about 1 ton before implementation to about 0.38 ton, with significant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a structural diagram of a phosgenation tail gas alkali destruction device during operation.

[0030] Figure 2 This is a structural diagram of a phosgenation tail gas alkali destruction device with the alkali destruction tower not in operation.

[0031] Figure 3 The present invention is a structural diagram of the operation of an alkali destruction tower of a phosgenation tail gas alkali destruction device.

[0032] The accompanying drawings in the specification include: 1. catalytic hydrolysis box; 101. nozzle; 102. catalyst; 103. permeable membrane; 104. water flow outlet; 2. reflux end; 3. through end; 4. first alkali destruction tower; 401. first air outlet; 402. first liquid inlet; 403. tower plate; 404. baffle; 405. slide plate; 406. insert plate; 407. air inlet plate; 408. cleaning brush; 409. connecting rod; 410. filter plate; 411. first First air inlet; 412, downcomer plate; 413, first liquid outlet; 5, second alkali destruction tower; 501, second air outlet; 502, second liquid inlet; 503, second air inlet; 504, second liquid outlet; 6, third alkali destruction tower; 601, third air outlet; 602, third liquid inlet; 603, third air inlet; 604, third liquid outlet; 7, falling film absorber; 8, phosgene detection device; 9, waste gas incineration device; 10, alkali wastewater tank. DETAILED DESCRIPTION

[0033] Basically as attached Figure 1 , Figure 2 As shown:

[0034] This solution provides a phosgenation tail gas alkali destruction device, comprising a catalytic hydrolysis box 1, a phosgene detection device 8, an alkali destruction tower, a pH detector and a falling film absorber 7, wherein the falling film absorber 7, the catalytic hydrolysis box 1, the phosgene detection device 8, the first alkali destruction tower 4, the second alkali destruction tower 5, the third alkali destruction tower 6, and the pH detector are connected in sequence;

[0035] The alkali destruction tower includes a cleaning mechanism, a tower body, a tower plate 403 and a downcomer plate 412. The tower plate 403 is fixedly connected to the tower body, and the tower plate 403 is fixedly connected to the downcomer plate 412. The tower body is provided with an air outlet, a liquid inlet, an air inlet and a liquid outlet. The cleaning mechanism includes an air inlet plate 407, a filter plate 410 and a cleaning brush 408. The air inlet plate 407 is fixedly connected to the filter plate 410 at a certain angle. The connection between the air inlet plate 407 and the filter plate 410 is rotatably connected to the tower body through a torque spring. When no gas enters from the air inlet, the air inlet plate 407 covers the air inlet under the action of the torque spring, so that the air inlet is closed, and the filter plate 410 passes through the brush needle of the cleaning brush 408. When gas is introduced, the gas rotates the air inlet plate 407, and at the same time drives the filter plate 410 to rotate, so that the filter plate 410 covers the liquid outlet, forming a filter screen effect. The cleaning brush 408 is fixedly connected to the tower body. It also includes a high-salt wastewater treatment device, the liquid outlet is connected to the high-salt wastewater treatment device. It also includes a waste gas incineration device 9, the gas outlet is connected to the waste gas incineration device 9.

[0036] It also includes a liquid overflow prevention mechanism, which includes a connecting rod 409, a slide plate 405, a baffle 404 and an insert plate 406. The tower plate 403 is provided with a groove, the insert plate 406 is slidably connected to the groove, the insert plate 406 is fixedly connected to the slide plate 405, the baffle 404 is fixedly connected to the tower body, the baffle 404 is slidably connected to the slide plate 405, one end of the connecting rod 409 is hinged to the slide plate 405, and the other end is hinged to the filter plate 410.

[0037] The catalytic hydrolysis box 1 includes a box body, a nozzle 101 and a permeable membrane 103. The box body is provided with a water flow port 104, an air flow port and an exhaust port. The nozzle 101 is connected to the water flow port 104. There are 5 permeable membranes 103 and 3 nozzles 101. The permeable membrane 103 is fixed on the box body from top to bottom to form a barrier-like barrier. The nozzle 101 is located between the two permeable membranes 103. The inner layer of the permeable membrane 103 is filled with a catalyst 102, and the air flow port is aligned with the permeable membrane 103.

[0038] It also includes a phosgene detection device, one end of the phosgene detection device 8 is connected to the exhaust port, and the other end is connected to the air inlet. The phosgene detection device 8 is provided with a reflux end 2, and the reflux end 2 is connected to the air flow port.

[0039] There are three alkali destruction towers. The first gas outlet 401 of the first alkali destruction tower 4 is connected to the gas inlet of the second alkali destruction tower 5, the second gas outlet 501 of the second alkali destruction tower 5 is connected to the third gas inlet 603 of the third alkali destruction tower 6, the first liquid outlet 413 of the first alkali destruction tower 4 is connected to the liquid inlet of the second alkali destruction tower 5, the second liquid outlet 504 of the second alkali destruction tower 5 is connected to the third liquid inlet 602 of the third alkali destruction tower 6, the third liquid outlet 604 is connected to the high-salt wastewater treatment device, and the third gas outlet 601 is connected to the waste gas incineration device 9.

[0040] During the specific operation, the operator first passes the exhaust gas into the falling film absorber 7 to remove the hydrochloric acid in the exhaust gas, and then passes the subsequent gas into the catalytic hydrolysis box 1. The water flow port 104 starts to take in water. The nozzle 101 is located between the two permeable membranes 103. The nozzle 101 sprays water and sprinkles the water on the catalyst 102 in the permeable membrane 103. When the gas is passed in from the air flow port, the gas will impact the permeable membrane 103, and pass through the permeable membrane 103 to contact the catalyst 102, and react. The catalytic hydrolysis method destroys the phosgene therein. This mechanism makes the catalytic reaction more thorough.

[0041] Then the gas coming out enters the phosgene detection device 8, which can check whether the gas coming out of the catalytic hydrolysis box 1 contains phosgene to prevent the phosgene from being not treated cleanly. If it contains phosgene, the phosgene returns to the gas flow outlet from the reflux end 2 for catalytic hydrolysis again. If it does not contain phosgene, it passes through the through end 3 to the first alkali destruction tower 4.

[0042] Then the gas is passed into the first alkali destruction tower 4, and the gas is passed in from the first air inlet 411. As the gas enters, the air inlet plate 407 is pushed open, and the filter plate 410 is driven to rotate until the filter plate 410 contacts and covers the liquid outlet, playing a role of filtering particles. At the same time, the liquid is passed in from the first liquid inlet 402 at the top of the tower, and the gas and liquid flow back and forth, increasing the contact area between the two, so that the reaction is maximized. The tower plate 403 can slow down the liquid falling speed, so that the gas-liquid contact time is increased. When the tail gas treatment is completed, the device stops, and the air inlet plate 407 returns to its original position under the action of the torque spring, and the filter plate 410 is tilted up at the same time, so that the filter plate 410 contacts the brush needle of the cleaning brush 408, and the brush needle passes through the filter hole of the filter plate 410 to clean the particles adhering to it, so that the staff does not need to dismantle the alkali destruction tower to replace the filter.

[0043] When the alkali destruction tower is flooded, the bottom gas cannot pass through the upper liquid, which increases the pressure below, and reduces the flow rate of the gas into the air inlet, causing the air inlet plate 407 to slowly move back due to the action of the torque spring, and at the same time causing the filter plate 410 to start moving, the filter plate 410 drives the connecting rod 409 to move, the connecting rod 409 drives the slide plate 405 to move, and the slide plate 405 drives the insertion plate 406 to pull out. The insertion plate 406 is a thin plate with filter holes. The pulling out of the insertion plate 406 makes the tower plate 403 longer and the filter holes more, making it easier for the liquid to fall, and at the same time, the gap between the downcomer plate 412 and the slide plate 405 becomes larger, so that the liquid has more space to pass through the gas, solving the problem of flooding. When the air pressure in the tower returns to normal, the air inlet air flow rate returns to normal, the air inlet plate 407 is pushed to the limit position again, and the filter plate 410 also covers the liquid outlet to filter out impurities.

[0044] The gas of the first alkali destruction tower 4 is led to the second air inlet 503 of the second alkali destruction tower 5, and the liquid of the first alkali destruction tower 4 is led to the second liquid inlet 502 of the second alkali destruction tower 5 for secondary reaction, and the gas of the second alkali destruction tower 5 is led to the third air inlet 603 of the third alkali destruction tower 6, and the liquid of the second alkali destruction tower 5 is led to the third liquid inlet 602 of the third alkali destruction tower 6 for tertiary reaction, and the three alkali destruction towers react layer by layer to make the reaction more thorough. Then there are still some carbon monoxide and organic gases remaining in the gas coming out of the third alkali destruction tower 6, which can be removed by burning through the waste gas incineration device 9. The high-salt wastewater coming out of the third alkali destruction tower 6 can be effectively utilized by the high-salt wastewater treatment device to prevent waste.

[0045] This scheme also provides a method for phosgenation tail gas alkali destruction, comprising the following steps:

[0046] Step S10: passing the tail gas into the falling film absorber 7, the falling film absorber 7 absorbs the hydrochloric acid in the tail gas to obtain a treated gas 1;

[0047] Step S20: passing the treated gas 1 into the catalytic hydrolysis box 1, destroying the phosgene therein by catalytic hydrolysis to obtain the treated gas 2;

[0048] Step S30: passing the treated gas 2 into a multi-stage alkali destruction tower, and delivering a 3.5%-4% dilute alkali solution to the top of the alkali destruction tower through a delivery pump. After the pH value of the alkali solution is monitored online and drops to 7.5-7.8, it is automatically introduced into the alkali wastewater tank 10 to be delivered to the high-salt wastewater treatment device to generate an inorganic salt solution and treated gas 3 through an acid-base reaction;

[0049] Step S40: Send the inorganic salt solution to the high-salt wastewater treatment device for treatment, and send the treated gas 3 to the waste gas incineration device 9 for treatment to remove unreacted carbon monoxide and combustible gases such as organic matter to obtain the final gas, which is discharged to the outside.

[0050] This method greatly improves the efficiency of tail gas treatment and reduces the output of high-salt wastewater. At the same time, the sodium hydroxide solution at this concentration reacts more thoroughly with the tail gas. According to statistics, the company's wastewater discharge per ton of product has been reduced from about 1 ton before implementation to about 0.38 tons, with significant results.

[0051] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A phosgenation tail gas alkali destruction device, comprising a catalytic hydrolysis box (1), It is characterized in that It also includes an alkali destruction tower, a pH detector and a falling film absorber, wherein the falling film absorber, the catalytic hydrolysis box (1), the alkali destruction tower and the pH detector are connected in sequence; The alkali destruction tower comprises a cleaning mechanism. A tower plate (403) is provided in the tower body. The cleaning mechanism comprises an air intake plate (407), a filter plate (410) and a cleaning brush (408). The air intake plate (407) is fixedly connected to the filter plate (410). The air intake plate (407) cooperates with the air inlet. The filter plate (410) cooperates with the liquid outlet. The connection between the air intake plate (407) and the filter plate (410) is rotatably connected to the tower body through a torque spring. The filter plate (410) cooperates with the cleaning brush (408). The cleaning brush (408) is fixedly connected to the tower body.

2. A phosgenation tail gas alkali destruction device according to claim 1, It is characterized in that The invention also includes a liquid flooding prevention mechanism, which includes a connecting rod (409), a slide plate (405), a baffle plate (404) and an insert plate (406); the tower plate (403) is provided with a groove; the insert plate (406) is slidably connected to the groove; the insert plate (406) is fixedly connected to the slide plate (405); the baffle plate (404) is fixedly connected to the tower body; the baffle plate (404) is slidably connected to the slide plate (405); one end of the connecting rod (409) is hingedly connected to the slide plate (405); and the other end is hingedly connected to the filter plate (410).

3. A phosgenation tail gas alkali destruction device according to claim 1, It is characterized in that It also includes a high-salt wastewater treatment device, and the liquid outlet is connected to the high-salt wastewater treatment device.

4. A phosgenation tail gas alkali destruction device according to claim 1, It is characterized in that It also includes an incineration device, and the gas outlet is connected to the incineration device.

5. The phosgenation tail gas alkali destruction device according to claim 1, It is characterized in that The catalytic hydrolysis box (1) comprises a box body, a nozzle (101) and a permeable membrane (103); the box body is provided with a water flow port (104), an air flow port and an exhaust port; the nozzle (101) is connected to the water flow port (104); a plurality of permeable membranes (103) are provided; the nozzle (101) cooperates with the permeable membrane (103); the air flow port is aligned with the permeable membrane (103); and a catalyst (102) is provided in the permeable membrane (103).

6. The phosgenation tail gas alkali destruction device according to claim 1, It is characterized in that It also comprises a phosgene detection device, one end of which is connected to the exhaust port, and the other end of which is connected to the air inlet. The phosgene detection device is provided with a reflux end (2), and the reflux end (2) is connected to the air flow port.

7. A phosgenation tail gas alkali destruction device according to claim 4, It is characterized in that The alkali destruction towers are provided with three, the first gas outlet (401) of the first alkali destruction tower (4) is connected to the gas inlet of the second alkali destruction tower (5), the second gas outlet (501) of the second alkali destruction tower (5) is connected to the third gas inlet (603) of the third alkali destruction tower (6), the first liquid outlet (413) of the first alkali destruction tower (4) is connected to the liquid inlet of the second alkali destruction tower (5), the second liquid outlet (504) of the second alkali destruction tower (5) is connected to the third liquid inlet (602) of the third alkali destruction tower (6), the third liquid outlet (604) is connected to a high-salt wastewater treatment device, and the third gas outlet (601) is connected to an incineration device.

8. A method for destroying phosgenation tail gas with alkali, It is characterized in that The following steps are involved: step S10: passing the tail gas into a falling film absorber, which absorbs hydrochloric acid in the tail gas to obtain a treated gas 1; Step S20: passing the treated gas 1 into the catalytic hydrolysis box (1) to destroy the phosgene therein by catalytic hydrolysis to obtain treated gas 2; Step S30: passing the treated gas 2 into a multi-stage alkali destruction tower, delivering a 1%-10% dilute alkali solution to the top of the alkali destruction tower through a delivery pump, and automatically introducing the alkali solution into an alkali wastewater tank after the alkali solution pH value drops to 7.5-10 after online monitoring, and then being delivered to a high-salt wastewater treatment device to generate an inorganic salt solution and treated gas 3 through an acid-base reaction; Step S40: Send the inorganic salt solution to a high-salt wastewater treatment device for treatment, and send the treated gas to an incineration device for treatment to remove unreacted carbon monoxide and organic combustible gases to obtain final gas, which is discharged to the outside.

9. A method for alkali destruction of phosgenation tail gas according to claim 8, It is characterized in that The dilute alkaline solution in step S30 is a 3.5%-4% sodium hydroxide solution.

10. A method for alkali destruction of phosgenation tail gas according to claim 8, It is characterized in that In the step S30, the alkali solution is directly discharged after the pH value of the alkali solution is monitored online at 7.5-7.8.

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