High-efficiency alkali washing device for recovering monomers from polyvinyl chloride polymerization kettle by suspension method

Abstract

The utility model discloses a high-efficiency alkali washing device for a suspension method polyvinyl chloride polymeric kettle recovered monomer, belongs to the technical field of chemical production processes, and aims to solve the problems of equipment corrosion, product performance degradation and subsequent process efficiency reduction caused by low pH value of the recovered monomer. The device comprises a polymerization kettle, a foam catcher, an alkaline washing tower, a gas holder, a water separator, a recovery compressor, a primary condenser, a secondary condenser, a pressure swing adsorption device and a PLC (Programmable Logic Controller), the top of the polymerization kettle is connected with a foam catcher, the foam catcher is connected with an alkaline washing tower (matched with an alkaline liquor circulating tank and a circulating pump), the alkaline washing tower is connected with a gas cabinet and a water separator, the water separator is sequentially connected with a recovery compressor, a multi-stage condenser and a pressure swing adsorption device, and a PLC (Programmable Logic Controller) controls pressure and a valve. The device can stabilize the pH value of the recovered monomer at 6-9, reduces equipment corrosion, improves the monomer recovery rate, realizes automatic control, is environment-friendly and economical, and is suitable for monomer recovery in suspension method polyvinyl chloride production.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of chemical production process technology, specifically relates to a kind of high-efficiency caustic wash device of monomer recovery of suspension method polyvinyl chloride polymerization kettle. BACKGROUND

[0002] In the current suspension method polyvinyl chloride production process, mainly using polymerization kettle to add monomer, desalination water and various auxiliary materials and small material additives for reaction, and the polyvinyl chloride slurry of reaction completion is transported to subsequent stripping device by discharge pump, removes residual chloroethylene, and then enters drying system for drying air to send packaging.

[0003] In this production process, especially in the use of suspension polymerization process, part of monomer in polymerization kettle is not completely converted into polymer, but exists in the form of unreacted gaseous state in polymerization reaction mixture, and in stripping process, residual chloroethylene monomer is removed from PVC slurry efficiently. Since chloroethylene is a toxic and volatile organic compound, residual in PVC product not only affects the performance of product, but also poses a threat to the environment and human health, therefore, in order to improve monomer utilization, reduce raw material waste, reduce production cost and reduce environmental pollution, monomer recovery step in polymerization kettle and stripping tower becomes particularly important, and recovery system is usually set in polymerization device for recycling and utilization of chloroethylene.

[0004] During the operation of recovery system, chloroethylene PH value is low, and the reasons are mainly caused by the following factors. If the catalyst or initiator used in polymerization reaction is not completely neutralized or removed, it will leave acidic residues in the recovered monomer, resulting in low pH value; some monomers may have certain acidity, or acidic by-products may be generated during the reaction, which may affect the pH value of the recovered monomer; metal parts (such as iron, copper, etc.) of polymerization reaction equipment or recovery system may release metal ions due to corrosion, and these metal ions may react with water to generate acidic substances, thereby reducing the pH value; if the pH value of cooling water or cleaning water used is low, it may also affect the pH value of the recovered monomer; at the same time, low PH value of recovered monomer will have the following effects on continuous production:

[0005] 1. Low PH of recovered monomer will accelerate the corrosion of metal equipment and pipeline of recovery system, shorten the service life of equipment and increase the maintenance cost.

[0006] 2. If the acidic substances in the recovered monomer are not effectively removed, it may cause performance problems of new polymer product, such as color change, mechanical property decline, etc.

[0007] 3. Deviation of pH value from the optimal range may affect the efficiency of subsequent process, such as affecting the efficiency of initiator, reducing the speed and selectivity of polymerization reaction. The utility model discloses a content

[0008] The utility model discloses a content

[0009] In order to realize above-mentioned purpose, the utility model adopts technical scheme for:

[0010] A kind of high-efficiency caustic washing device of monomer recovery of suspension method polyvinyl chloride polymerizer, including polymerizer, the bottom of the polymerizer is equipped with valve F10 and pipeline C, the top of the polymerizer is connected with foam catcher by pipeline G1, the top of the foam catcher is connected with caustic washing tower by pipeline G3, the top of the caustic washing tower is connected with gas cabinet by pipeline G4, the gas cabinet is connected with water separator by pipeline G5, the water separator is connected with lye circulating tank by pipeline G11, the top of the lye circulating tank is equipped with pipeline J1 and valve F8, the bottom of the lye circulating tank is connected with caustic washing tower by pipeline J3, lye circulating pump is equipped on the pipeline J3, the bottom of the caustic washing tower is connected with lye circulating tank by pipeline J2, one side of the bottom of the lye circulating tank is equipped with pipeline J4, valve F11 is equipped on the pipeline J4.

[0011] Preferably, the top of the water separator is connected with recovery compressor by pipeline G6, the recovery compressor is connected with primary condenser and secondary condenser in series by pipeline G7 and pipeline G8, the bottom of the primary condenser and secondary condenser is connected with recovery monomer tank by pipeline G12, the bottom of the recovery monomer tank is equipped with pipeline and valve F7, the recovery monomer tank is connected with recovery monomer pump by pipeline G14, the liquid outlet of the recovery monomer pump is connected with polymerizer by pipeline G14, valve F4 is equipped on the pipeline G14.

[0012] Preferably, the bottom of the secondary condenser is connected with pressure swing adsorption by pipeline, the top of the pressure swing adsorption is connected with gas cabinet by pipeline G9, valve F9 is equipped on the pipeline G9, one side of the pressure swing adsorption is equipped with pipeline G10.

[0013] Preferably, pressure gauge P1 and pressure gauge P2 are respectively arranged on the gas phase outlet pipeline of the primary condenser and secondary condenser, the bottom of the primary condenser and secondary condenser is respectively equipped with pipeline, adjusting valve F5 and adjusting valve F6 are respectively arranged on the pipeline, the pressure gauge P1, pressure gauge P2, adjusting valve F5 and adjusting valve F6 are connected with PLC controller by signal.

[0014] Preferably, the top of the polymerization kettle is provided with a pressure gauge P, the pipeline G1 is sequentially provided with an adjusting valve F1 and a pressure gauge P3, the pipeline G1 is provided with a bypass pipeline G2, the pipeline G2 is sequentially provided with an adjusting valve F2 and a recovery vacuum pump, the outlet of the recovery vacuum pump is connected with the adjusting valve F1 of the pipeline G1 through a pipeline, and the adjusting valve F1, the adjusting valve F2, the pressure gauge P, the recovery pressure gauge P3 and the recovery vacuum pump are connected with a PLC controller through a signal connection.

[0015] Preferably, the bottom of the foam trap is connected with a foam pump through a pipeline, the foam pump is connected with a monomer tank through a pipeline G15, the bottom of the monomer tank is connected with a monomer pump through a pipeline G16, the outlet of the monomer pump is connected with a pipeline G18 through a pipeline G17, the end of the pipeline G18 is connected to the top of the polymerization kettle, and a valve F4 is arranged at the connection position of the pipeline G17 and the pipeline G18.

[0016] The polymeric kettle is a 108m³ vertical reaction kettle, is a core equipment for realizing efficient and controllable polymerization reaction, is equipped with temperature and pressure sensors and a corresponding control system on the kettle, and realizes real-time monitoring of reaction conditions, so that the safety and stability of the reaction process are ensured; monomers are added from the top of the polymerization kettle, a discharge port and an adjusting valve are arranged at the bottom, and a recovery pipeline is arranged at the top of the polymerization kettle.

[0017] The polymeric kettle is a 108m³ vertical reaction kettle, is a core equipment for realizing efficient and controllable polymerization reaction, is equipped with temperature and pressure sensors and a corresponding control system on the kettle, and realizes real-time monitoring of reaction conditions, so that the safety and stability of the reaction process are ensured; monomers are added from the top of the polymerization kettle, a discharge port and an adjusting valve are arranged at the bottom, and a recovery pipeline is arranged at the top of the polymerization kettle.

[0018] The polymeric kettle is a 108m³ vertical reaction kettle, is a core equipment for realizing efficient and controllable polymerization reaction, is equipped with temperature and pressure sensors and a corresponding control system on the kettle, and realizes real-time monitoring of reaction conditions, so that the safety and stability of the reaction process are ensured; monomers are added from the top of the polymerization kettle, a discharge port and an adjusting valve are arranged at the bottom, and a recovery pipeline is arranged at the top of the polymerization kettle.

[0019] The foam trap is mainly used to remove excess foam or vinyl chloride droplets suspended in the gas generated during the recovery process of vinyl chloride to maintain the stability of the process and improve the quality of the product. It is usually made of porous materials such as metal wire mesh, fiber membrane or ceramic, etc. These materials have a certain pore structure. When the gas containing foam or droplets passes through the trap, the foam or droplets are hit and adhered to the surface of the trap or intercepted in the pores due to the effects of inertia, diffusion force and surface tension. In the area where the gas flow slows down, the droplets settle and coalesce into larger droplets due to gravity and deposit at the bottom of the trap. The foam trap is provided with a liquid level meter and a foam pump at the bottom to pump the deposited liquid phase vinyl chloride monomer to the monomer tank for reuse.

[0020] A pipeline is connected to the caustic washing tower at the outlet of the foam trap. The caustic washing tower is mainly used to remove acidic gases and impurities carried by the recovered vinyl chloride. Through chemical neutralization reaction, the PH value of the recovered vinyl chloride monomer is controlled between 6-9. The caustic washing tower is sequentially provided with an air inlet, a packing layer, a spraying layer, a demisting layer and a top outlet from bottom to top.

[0021] The air inlet of the caustic washing tower is the position where the recovered vinyl chloride enters the tower, which is set at the bottom of the tower. The packing layer needs to be designed, such as Raschig ring, Pall ring, etc., to increase the gas-liquid contact area and promote the mass transfer process. The spraying layer is provided with nozzles for uniformly spraying alkali solution onto the packing layer to ensure that the alkali solution and the recovered vinyl chloride gas are in full contact and reaction. The demisting layer recovers the liquid droplets carried by the recovered vinyl chloride through a demister (such as a wire mesh demister) to prevent the alkali solution from being discharged with the gas and keep the recovered vinyl chloride gas clean. The top outlet of the caustic washing tower facilitates the discharge of the purified vinyl chloride gas therefrom. The caustic washing tower is designed to operate at a pressure of 0.1-0.5 MPa, which can be adjusted by the outlet pressure of the polymerization kettle recovery regulating valve and the recovery vacuum pump.

[0022] The caustic washing tower is provided with an alkali solution circulating tank. An alkali solution pipeline and valve are provided at the top of the alkali solution circulating tank, and an alkali solution circulating pump is provided at the bottom of the alkali solution circulating tank. The alkali solution in the circulating tank is pumped to the top of the caustic washing tower, flows into the alkali solution circulating tank from the bottom after spraying, and is recycled. The alkali solution circulating tank needs to be provided with a gas phase balance pipe at the top of the caustic washing tower to facilitate normal alkali washing circulation. Through the contact reaction of the recovered vinyl chloride gas and the alkali solution, the PH value of the vinyl chloride at the outlet of the caustic washing tower can be stabilized between 6-9. The design requires that the concentration of the alkali solution be 5%-15%, and the alkali concentration be less than 5% to replace the alkali solution.

[0023] The alkali washing tower top outlet is connected to a recovery gas tank by a pipeline. The gas tank is a wet single-section gas tank. The vinyl chloride gas tank is used as an intermediate storage device to balance the difference between the vinyl chloride recovery amount and the subsequent recovery compressor suction amount. When the recovery amount exceeds the compressor suction amount, the gas tank liquid level rises. When the recovery compressor suction amount is greater than the recovery amount, the gas tank liquid level drops, thereby ensuring the continuity and stability of the production process.

[0024] The vinyl chloride gas tank is a wet gas tank, which results in a higher moisture content of the recovered vinyl chloride at the outlet. A moisture separator is provided after the recovery gas tank is connected by a pipeline. The main function of the moisture separator is to separate and remove moisture from the vinyl chloride gas stream to ensure gas dryness, ensure the moisture content of the recovered vinyl chloride monomer, and improve the use efficiency of the gas and the overall reliability of the system.

[0025] The moisture separator and the alkali liquor circulating tank are provided with a high height difference. The field height of the moisture separator is higher than the top of the alkali liquor circulating tank. A U-shaped liquid seal pipe is provided at the bottom of the moisture separator to flow the water collected in the moisture separator to the alkali liquor circulating tank by gravity settling.

[0026] A recovery compressor is provided at the outlet of the moisture separator. The vinyl chloride gas is sucked and compressed into a smaller volume by compression. During this process, the vinyl chloride gas molecules are forced to approach each other, and the pressure and temperature of the vinyl chloride gas rise. The purpose of compression is to increase the pressure of the vinyl chloride gas to make it easy to liquefy and prepare for the subsequent condensation recovery. The outlet pressure of the recovery compressor is designed to be 0.4-0.6 MPa. This pressure can be achieved by a two-stage condenser outlet pressure transmitter interlocking circulating water and a 5°C water regulating valve.

[0027] The recovery compressor is designed to use a water ring compressor. The water ring compressor has the advantages of simple structure, reliable operation, easy maintenance, environmental protection, no oil, and strong adaptability. The water ring compressor is used to compress the vinyl chloride gas phase from the moisture separator, which is convenient for subsequent condensation recovery.

[0028] A first-stage condenser and a second-stage condenser are provided in sequence at the outlet of the recovery compressor. The condenser is a shell-and-tube heat exchanger. The high-temperature and high-pressure vinyl chloride at the outlet of the compressor passes through the tube side of the first-stage condenser and the second-stage condenser in sequence. The vinyl chloride monomer is condensed by circulating water and 5°C water flowing through the shell side of the first-stage condenser and the second-stage condenser. The condensed liquid flows into the recovery monomer tank through the bottom of the first-stage condenser and the second-stage condenser. After the uncondensed gas is adsorbed by the pressure swing adsorption device, the vinyl chloride is recovered to the gas tank for reuse, and the inert gas is discharged through the pressure swing adsorption discharge port.

[0029] The pressure swing adsorption is based on the difference in adsorption capacity of different gas components by the adsorbent and the change in this adsorption capacity with pressure. An adsorbent with high affinity for vinyl chloride is loaded in the adsorption tower. Vinyl chloride is sent back to the gas tank for reuse by desorption, and the unadsorbed inert gas is discharged to meet the standard.

[0030] The bottom of the monomer recovery tank is provided with a precipitator, which facilitates the settlement of trace moisture in the monomer and discharges the trace moisture to a sewage treatment system at regular intervals by manual operation. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a structure schematic view of the utility model;

[0032] In the figure: 1-polymerization kettle; 2-recovery vacuum pump; 3-foam catcher; 4-foam pump; 5-monomer tank; 6-monomer pump; 7-gas cabinet; 8-alkali washing tower; 9-alkali liquor circulating pump; 10-alkali liquor circulating tank; 11-water separator; 12-recovery compressor; 13-first-stage condenser; 14-second-stage condenser; 15-pressure swing adsorption; 16-recovery monomer tank; 17-recovery monomer pump; 18-PLC controller. DETAILED DESCRIPTION

[0033] The utility model will be further described in connection with the drawings and specific embodiments:

[0034] As Figure 1 shown in a kind of high-efficiency alkali washing device of monomer recovery of suspension method polyvinyl chloride polymerization kettle, including polymerization kettle 1, the bottom of polymerization kettle 1 is equipped with valve F10 and pipeline C, the top of polymerization kettle 1 is connected with foam catcher 3 by pipeline G1, the top of foam catcher 3 is connected with alkali washing tower 8 by pipeline G3, the top of alkali washing tower 8 is connected with gas cabinet 7 by pipeline G4, gas cabinet 7 is connected with water separator 11 by pipeline G5, water separator 11 is connected with alkali liquor circulating tank 10 by pipeline G11, the top of alkali liquor circulating tank 10 is equipped with pipeline J1 and valve F8, the bottom of alkali liquor circulating tank 10 is connected with alkali washing tower 8 by pipeline J3, alkali liquor circulating pump 9 is equipped on pipeline J3, the bottom of alkali washing tower 8 is connected with alkali liquor circulating tank 10 by pipeline J2, the bottom of alkali liquor circulating tank 10 is equipped with pipeline J4 on one side, valve F11 is equipped on pipeline J4. The alkali washing tower 8 is designed with alkali liquor circulating tank 10, alkali liquor circulating tank 10 top is provided with alkali preparation pipeline J1 and valve F8, alkali liquor circulating pump 9 is arranged at the bottom of alkali liquor circulating tank 10, and the alkali liquor in the circulating tank is pumped to the top of alkali washing tower 8 by pipeline J3, after spraying, the alkali liquor flows into alkali liquor circulating tank 10 from the bottom of the tower by pipeline J2 for recycling, and the alkali concentration is required to be 5%-15%, and fresh alkali liquor is replaced when the alkali concentration is less than 5%, which can be discharged from pipeline J2 and valve F11 at the bottom of alkali liquor circulating tank and then replaced with fresh alkali liquor. The above operation can ensure that the PH value of vinyl chloride at the outlet of alkali washing tower 8 is stable between 6-9.

[0035] The top of the water separator 11 is connected with a recovery compressor 12 through a pipeline G6, the recovery compressor 12 is connected with a first-stage condenser 13 and a second-stage condenser 14 through a pipeline G7 and a pipeline G8 in series, the bottom of the first-stage condenser 13 and the second-stage condenser 14 is connected with a recovery monomer tank 16 through a pipeline G12, the bottom of the recovery monomer tank 16 is provided with a pipeline and a valve F7, a drain pipeline is arranged at the bottom of the recovery monomer tank, and the recovery monomer tank is drained regularly by opening the valve F7. The recovery monomer tank 16 is connected with a recovery monomer pump 17 through a pipeline G14, the liquid outlet of the recovery monomer pump 17 is connected with the polymerizer 1 through the pipeline G14, and the pipeline G14 is provided with a valve F4.

[0036] The bottom of the second-stage condenser 14 is connected with a pressure swing adsorption 15 through a pipeline, the top of the pressure swing adsorption 15 is connected with the gas tank 7 through a pipeline G9, the pipeline G9 is provided with a valve F9, and one side of the pressure swing adsorption 15 is provided with a pipeline G10.

[0037] Pressure gauges P1 and P2 are arranged on the gas phase outlet pipelines of the first-stage condenser 13 and the second-stage condenser 14 respectively, the bottoms of the first-stage condenser 13 and the second-stage condenser 14 are respectively provided with pipelines, the pipelines are respectively provided with regulating valves F5 and F6, and the pressure gauges P1, P2, the regulating valves F5 and F6 are connected with a PLC controller 18 through signals. The outlet of the gas tank 7 is connected to the inlet of the water separator 11 through a pipeline G5, and the bottom of the water separator 6 is connected to the alkali liquor circulating tank 10 through a pipeline G11 after being connected to a U-shaped liquid seal. The outlet of the water separator 11 is connected to the inlet of the recovery compressor 12 through a pipeline G6, the outlet of the recovery compressor 12 is sequentially connected to the pipeline of the first-stage condenser 13 and the second-stage condenser 14 through pipelines G7 and G8, pressure gauges P1 and P2 are arranged on the gas phase outlet pipelines of the first-stage condenser 13 and the second-stage condenser 14 respectively, and the PLC controller 18 is connected with P1, P2, a circulating water regulating valve F5 and a 5°C water regulating valve F6 to set interlocking (interlocking two), and the system automatically adjusts the opening degrees of the valves F5 and F6 to control the recovery system pressure to be stable at 0.4Mpa-0.6Mpa.

[0038] The top of the polymerizer 1 is provided with a pressure gauge P, the pipeline G1 is sequentially provided with a regulating valve F1 and a pressure gauge P3, a bypass pipeline G2 is arranged on the pipeline G1, the pipeline G2 is sequentially provided with a regulating valve F2 and a recovery vacuum pump 2, and the liquid outlet of the recovery vacuum pump 2 is connected to the position of the regulating valve F1 of the pipeline G1 through a pipeline. The regulating valve F1, the regulating valve F2, the pressure gauge P, the recovery pressure gauge P3 and the recovery vacuum pump 2 are connected with the PLC controller 18 through signals. The regulating valves F1 and F2, the pressure gauges P and P3 and the recovery vacuum pump 2 are set to be interlocked through the PLC controller 18, and the interlocking logic is as follows:

[0039] 1. The recovered pressure gauge P3 is connected with the regulating valve F1 and the regulating valve F2 by the PLC controller 18, and the operation pressure of the caustic washing tower is controlled by the regulating valve switch to be 0.1-0.5 MPa.

[0040] 2. In the recovery process of the polymerizer, when the pressure P of the polymerizer 1 is less than 0.2 MPa, the recovery pipeline regulating valve F1 is closed, the recovery vacuum pump 2 inlet regulating valve F2 is opened, and the recovery vacuum pump 2 is started to operate; when the pressure P of the polymerizer is equal to-60 Kpa, the recovery vacuum pump 2 stops operating, the recovery pipeline G1 regulating valve F1 and the recovery vacuum pump 2 inlet regulating valve F2 are closed, and the recovery is completed; a plurality of polymerizers can set the recovery pipeline related instruments to be connected with the PLC control system and the recovery vacuum pump 2.

[0041] The bottom of the foam trap 3 is connected with the foam pump 4 through a pipeline, the foam pump 4 is connected with the monomer tank 5 through a pipeline G15, the bottom of the monomer tank 5 is connected with the monomer pump 6 through a pipeline G16, the liquid outlet of the monomer pump 6 is connected with the pipeline G18 through a pipeline G17, and the end of the pipeline G18 is connected to the top of the polymerizer 1; a valve F4 is arranged at the connection position of the pipeline G17 and the pipeline G18. The pipeline G1 is connected to the foam trap 3, and the liquid phase chloroethylene deposited at the bottom of the foam trap 3 is transported to the monomer tank 5 through the foam pump 5 and the pipeline G15, the bottom outlet of the monomer tank 5 is connected to the monomer pump 6 through the pipeline G16, the outlet of the monomer pump 6 is provided with the pipeline G17, and the chloroethylene is sent to the polymerizer monomer feeding pipeline G18 through the regulating valve F3. The pipeline G3 of the foam trap 3 is connected to the feeding inlet of the caustic washing tower 8, and the top outlet of the caustic washing tower 8 is connected to the gas tank 7 through the pipeline G4 and the valve F10.

[0042] The uncondensed gas at the gas phase outlet of the secondary condenser 14 is transported to the pressure swing adsorption system 15 through a pipeline, the adsorbed chloroethylene gas phase is transported to the gas tank 7 inlet through the pipeline G9 and the valve F9 and is combined with the pipeline G4, the chloroethylene is recycled, and the unadsorbed inert gas is discharged through the pipeline G10.

[0043] The utility model realizes the following operation method:

[0044] 1. All the system related valves are opened, nitrogen is connected to the system for pressure test and leakage test, and the pressure test is qualified at 1.0 MPa.

[0045] 2. The system is replaced by nitrogen, and the oxygen content is required to be less than or equal to 0.2% through multi-point sampling.

[0046] 3. The valve F8 is opened to configure the lye in the lye circulation tank 10 through the pipeline J1, and the lye concentration is required to be 5%-15%, and the liquid level is controlled to be 70%-80%.

[0047] 4, open the alkali circulating pump 9 to establish the alkali washing tower 8 and the alkali circulating tank 10 between the circulation.

[0048] 5, after the polymerization kettle began to discharge, the valve F10 was opened, and the polymerization kettle recovery chain was put into use.

[0049] 6, when the gas tank 7 liquid level is 65%, open the recovery compressor 12 to run, control the compressor pressure control chain to use, and open the pressure swing adsorption device to run.

[0050] 7, when the foam trap 3 liquid level is 60%, open the foam pump 4 to transport the liquid monomer to the monomer tank 5.

[0051] 8, observe the liquid level of the recovery monomer tank 16, and open the recovery monomer pump 17 in time to add the monomer in the recovery monomer tank 16 to other polymerization kettles to be fed.

[0052] 9, detect the pH value of the chloroethylene outlet of the alkali tower in time, regularly drain the bottom of the recovery monomer tank 16, and detect the pressure swing adsorption air index in time.

[0053] By using the above technical invention and operation, a high-efficiency alkali washing process for the recovery monomer of the suspension method polyvinyl chloride polymerization kettle can be realized, which can effectively prevent the problems in the above background.

Claims

1. A high-efficiency alkaline washing device for recovering monomers in a suspension polymerization reactor of polyvinyl chloride, comprising a polymerization reactor, characterized in that: The bottom of the polymerization kettle (1) is provided with valve F10 and pipeline C, the top of the polymerization kettle (1) is connected with foam catcher (3) through pipeline G1, the top of the foam catcher (3) is connected with caustic washing tower (8) through pipeline G3, the top of the caustic washing tower (8) is connected with gas tank (7) through pipeline G4, the gas tank (7) is connected with water separator (11) through pipeline G5, the water separator (11) is connected with caustic soda circulating tank (10) through pipeline G11, the top of the caustic soda circulating tank (10) is provided with pipeline J1 and valve F8, the bottom of the caustic soda circulating tank (10) is connected with caustic washing tower (8) through pipeline J3, the pipeline J3 is provided with caustic soda circulating pump (9), the bottom of the caustic washing tower (8) is connected with caustic soda circulating tank (10) through pipeline J2, one side of the bottom of the caustic soda circulating tank (10) is provided with pipeline J4, and the pipeline J4 is provided with valve F11.

2. The efficient caustic washing device for recovering monomers from a suspension process PVC polymerization reactor according to claim 1, characterized in that: The top of the water separator (11) is connected with recovery compressor (12) through pipeline G6, the recovery compressor (12) is connected with primary condenser (13) and secondary condenser (14) through pipeline G7 and pipeline G8 in series, the bottom of the primary condenser (13) and the secondary condenser (14) is connected with recovery monomer tank (16) through pipeline G12, the bottom of the recovery monomer tank (16) is provided with pipeline and valve F7, the recovery monomer tank (16) is connected with recovery monomer pump (17) through pipeline G14, the liquid outlet of the recovery monomer pump (17) is connected with polymerization kettle (1) through pipeline G14, and the pipeline G14 is provided with valve F4.

3. The efficient caustic washing device for recovering monomers from a suspension process PVC polymerization reactor according to claim 2, characterized in that: The bottom of the secondary condenser (14) is connected with pressure swing adsorption (15) through pipeline, the top of the pressure swing adsorption (15) is connected with gas tank (7) through pipeline G9, the pipeline G9 is provided with valve F9, and one side of the pressure swing adsorption (15) is provided with pipeline G10.

4. The efficient caustic washing device for recovering monomers of a suspension process PVC polymerization kettle according to claim 2, characterized in that: Pressure gauges P1 and P2 are arranged on the gas phase outlet pipelines of the primary condenser (13) and the secondary condenser (14) respectively, pipelines are arranged at the bottoms of the primary condenser (13) and the secondary condenser (14) respectively, adjusting valves F5 and F6 are arranged on the pipelines respectively, and the pressure gauges P1, P2, adjusting valves F5 and F6 are connected with PLC controller 18 through signals.

5. The efficient caustic washing device for recovering monomers from a suspension process PVC polymerization reactor according to claim 1, characterized in that: The top of the polymerization kettle (1) is provided with pressure gauge P, adjusting valve F1 and pressure gauge P3 are arranged on the pipeline G1 in sequence, bypass pipeline G2 is arranged on the pipeline G1, adjusting valve F2 and recovery vacuum pump (2) are arranged on the bypass pipeline G2 in sequence, the liquid outlet of the recovery vacuum pump (2) is connected with the position behind adjusting valve F1 of the pipeline G1 through a pipeline, adjusting valves F1 and F2, pressure gauges P and P3 and recovery vacuum pump (2) are connected with PLC controller (18) through signals.

6. The efficient caustic washing device for recovering monomers from a suspension process PVC polymerization reactor according to claim 1, characterized in that: The bottom of the foam trap (3) is connected with a foam pump (4) through a pipeline, the foam pump (4) is connected with a monomer tank (5) through a pipeline G15, the bottom of the monomer tank (5) is connected with a monomer pump (6) through a pipeline G16, the liquid outlet of the monomer pump (6) is connected with a pipeline G18 through a pipeline G17, the end of the pipeline G18 is connected to the top of the polymerizer (1), and a valve F4 is arranged at the connection position of the pipeline G17 and the pipeline G18.

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