System for producing polyvinyl chloride

Abstract

The utility model relates to a system for producing polyvinyl chloride, and belongs to the field of polyvinyl chloride production. The system for producing polyvinyl chloride comprises a storage configuration unit, a polymerization steam stripping unit, a vinyl chloride recovery unit, a polyvinyl chloride drying and packaging unit and a wastewater treatment unit, and the polymerization steam stripping unit is provided with a kettle top condenser for recovering vinyl chloride generated in each link in the system. Meanwhile, in the wastewater treatment unit, sewage and the like in the production process, ground sewage and the like jointly pass through a wastewater stripping tower and a wastewater stripping tower condenser, the unreacted vinyl chloride is condensed and recovered into the vinyl chloride recovery unit through steam stripping, and the unreacted vinyl chloride is recovered into the wastewater stripping tower condenser; and then the residual wastewater is treated by using the pretreatment reactor to remove pollutants and then is discharged, and in the wastewater treatment process, the vinyl chloride is recycled, so that the consumption of the vinyl chloride is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of polyvinyl chloride production, concretely relates to a system for producing polyvinyl chloride. BACKGROUND

[0002] The suspension polymerization method of polyvinyl chloride is the most widely used method for producing polyvinyl chloride at present, accounting for about 80% of the total PVC production. PVC resin produced by the suspension polymerization method has high purity and low impurity content, and has good electrical insulation and thermal stability. In the suspension polymerization method, monomers are suspended in water in the form of droplets, and free radical addition polymerization is carried out by an initiator and a stirrer to produce PVC particles. In order to ensure uniform dispersion of the particles, a suspension stabilizer and the like need to be added, and the temperature and pressure of the polymerization process need to be controlled.

[0003] CN110078851B discloses a polyvinyl chloride suspension polymerization method, comprising the steps of: a) adding a terminating agent to the polyvinyl chloride suspension polymerization system to terminate polymerization, centrifuging and purifying the water phase reaction mixture of the suspension polymerization to obtain a centrifugal mother liquor; b) recycling the centrifugal mother liquor as a reaction raw material back to the vinyl chloride suspension polymerization system for continuous polymerization; and c) repeating steps a) and b). In step a), the equivalent concentration of the polymerization inhibitor in the centrifugal mother liquor is controlled at 7.8 x 10 -6 N-3.1 x 10 - 5 N.

[0004] CN100491412C discloses an energy-saving type suspension method polyvinyl chloride drying method, which adopts a large air induction and small air blowing negative pressure operation process, and the power of the air induction fan is 2.5-3 times that of the air blowing fan. The drying bed is provided with spiral plates, flow-around columns, a group of conical guide plates and uniquely designed guide plates, so that the wet material flows smoothly and uniformly in the drying process, the input steam temperature is reduced from the past 140-160℃ to 110-120℃, and the drying time is shortened, which can save steam by 25-58% and electricity by 15%. It is an ideal suspension method polyvinyl chloride drying technology.

[0005] The process of producing polyvinyl chloride by the suspension method is mature, but a large amount of by-products and unreacted vinyl chloride and the like are produced in the polymerization process, which need to be recycled and reused by a post-treatment method to prevent pollution of the environment or harm to the safety of employees. In the existing recovery process of vinyl chloride, the vinyl chloride monomer needs to be recovered before the next reaction, which leads to an increase in the cycle of producing polyvinyl chloride, low production efficiency, and a complex method and equipment for recovering vinyl chloride, making it difficult for the workers to operate, and high production cost.

[0006] In summary, the process for preparing polyvinyl chloride by the suspension method has been widely used in industry, but the problems of recycling of unreacted vinyl chloride and by-product treatment in the preparation process have not been solved, the process of recycling and post-treatment is complex, the recycling process takes a long time, and the low production efficiency is still a problem to be solved. Utility model content

[0007] In view of the above problems, the utility model provides a system for producing polyvinyl chloride, through the condenser, the by-product and unreacted vinyl chloride in the reaction process are recycled, and the synthesis process of polyvinyl chloride is ensured to recycle vinyl chloride at the same time, the production efficiency is improved, the reaction cycle is shortened, and simultaneously, the utility model also increases the wastewater treatment system, in the treatment process of wastewater, vinyl chloride is recycled, the consumption of vinyl chloride is reduced, and the environmental protection of the system for producing polyvinyl chloride in the utility model is ensured.

[0008] The utility model provides a system for producing polyvinyl chloride, according to material transportation direction, the system includes storage configuration unit, polymerization stripping unit, vinyl chloride recovery unit, polyvinyl chloride drying and packaging unit and wastewater treatment unit;

[0009] The storage configuration unit includes desalted water tank, auxiliary agent storage tank, fresh vinyl chloride storage tank and recycled vinyl chloride storage tank;

[0010] The polymerization stripping unit includes polymerization kettle, kettle top condenser, discharge tank, stripping tower storage tank, polymerization heat exchanger, stripping tower, stripping tower condenser and mixing tank;

[0011] The vinyl chloride recovery unit includes recovery separator, compressor, primary condenser and secondary condenser;

[0012] The polyvinyl chloride drying and packaging unit includes centrifuge and drying bed;

[0013] The wastewater treatment unit includes condensation separator, water storage tank, wastewater heat exchanger, wastewater stripping tower, wastewater stripping tower condenser and pretreatment reactor.

[0014] Further, the polyvinyl chloride drying and packaging unit further includes cyclone separator and bag filter.

[0015] Further, the desalted water tank includes normal temperature desalted water tank, high temperature desalted water tank and low temperature desalted water tank;

[0016] The normal temperature desalted water tank, the high temperature desalted water tank and the low temperature desalted water tank are all provided with water inlet and water outlet;

[0017] Desalted water enters the water inlet of the normal temperature desalted water tank, the high temperature desalted water tank and the low temperature desalted water tank from the pipeline.

[0018] The low-temperature desalted water tank and the high-temperature desalted water tank are both provided with heat exchangers for cooling and heating the desalted water in the low-temperature desalted water tank and the high-temperature desalted water tank.

[0019] Further, the auxiliary agent storage tank is provided with an inlet and an outlet, and further provided with a stirring device.

[0020] Further, the fresh chloroethylene storage tank is provided with an inlet and an outlet.

[0021] Further, the recycled chloroethylene storage tank is provided with an inlet and an outlet.

[0022] Further, the polymerization kettle is provided with a hot desalted water inlet, a cold desalted water inlet, an inlet, an outlet, a gas phase outlet and a water outlet, the hot desalted water inlet of the polymerization kettle is connected with the water outlet of the normal-temperature desalted water tank and the high-temperature desalted water tank, the cold desalted water inlet of the polymerization kettle is connected with the water outlet of the low-temperature desalted water tank, the inlet of the polymerization kettle is connected with the outlet of the fresh chloroethylene storage tank and the recycled chloroethylene storage tank;

[0023] The polymerization kettle is provided with a stirring device;

[0024] The outer layer of the polymerization kettle is provided with a cooling water pipeline, and circulating cooling water is circulated in the cooling water pipeline.

[0025] Further, the kettle-top condenser is arranged on the top of the polymerization kettle for condensing the reaction materials in the polymerization kettle.

[0026] Further, the outlet tank is provided with an inlet, an outlet and a gas phase outlet, and further provided with a stirring device, and the inlet of the outlet tank is connected with the outlet of the polymerization kettle.

[0027] Further, the stripping tower storage tank is provided with an inlet, an outlet and a gas phase outlet, and further provided with a stirring device, and the inlet of the stripping tower storage tank is connected with the outlet of the outlet tank.

[0028] Further, the polymerization heat exchanger is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, and the cold material inlet of the polymerization heat exchanger is connected with the outlet of the stripping tower storage tank.

[0029] Further, the stripping tower is provided with an inlet, an outlet and a gas phase outlet, the inlet of the stripping tower is connected with the cold material outlet of the polymerization heat exchanger, and the outlet of the stripping tower is connected with the hot material inlet of the polymerization heat exchanger.

[0030] Further, the stripping tower condenser is provided with a gas phase inlet and a liquid outlet, and the gas phase inlet of the stripping tower condenser is connected with the gas phase outlet of the stripping tower.

[0031] Further, the mixing tank is provided with a feeding port and a discharging port, and a stirring device is further arranged in the mixing tank, and the feeding port of the mixing tank is connected with the hot material outlet of the polymer heat exchanger.

[0032] Further, the recovery separator is provided with a feeding port and a discharging port, and the feeding port of the recovery separator is connected with the gas phase outlets of the polymer kettle, the discharging tank and the stripping tower storage tank.

[0033] Further, the compressor is provided with a feeding port and a discharging port, and the feeding port of the compressor is connected with the discharging port of the recovery separator.

[0034] Further, the primary condenser is provided with a feeding port, a discharging port and a gas phase outlet, the feeding port of the primary condenser is connected with the discharging port of the compressor, and the discharging port of the primary condenser is connected with the feeding port of the recovered vinyl chloride storage tank.

[0035] Further, the secondary condenser is provided with a feeding port, a discharging port and a gas phase outlet, the feeding port of the secondary condenser is connected with the gas phase outlet of the primary condenser, the discharging port of the secondary condenser is connected with the feeding port of the recovered vinyl chloride storage tank, and the gas phase outlet of the secondary condenser is connected with the tail gas treatment device.

[0036] Further, the centrifuge is provided with a feeding port, a discharging port and a waste water outlet, and the feeding port of the centrifuge is connected with the discharging port of the mixing tank.

[0037] Further, the drying bed is provided with a feeding port, a discharging port and a gas outlet, the feeding port of the drying bed is connected with the discharging port of the centrifuge, and the material discharged from the discharging port of the drying bed is packaged.

[0038] Further, the cyclone separator is provided with a feeding port and a discharging port, and the feeding port of the cyclone separator is connected with the gas outlet of the drying bed.

[0039] Further, the bag filter is provided with a feeding port and an air outlet, the feeding port of the bag filter is connected with the discharging port of the cyclone separator, and the air outlet of the bag filter is connected with the tail gas treatment device.

[0040] Further, the condensing separator is provided with a water inlet, a water outlet and a material outlet, the water inlet of the condensing separator is connected with the liquid outlet of the stripping tower condenser, and the material outlet of the condensing separator is connected with the feeding port of the recovery separator.

[0041] Further, the water storage tank is provided with a water inlet and a water outlet, the water inlet of the water storage tank is connected with the water outlet of the condensing separator, and the water inlet of the water storage tank is also connected with the wastewater outlet of the centrifugal machine and the water outlet of the polymerization kettle.

[0042] The water storage tank is also provided with flushing wastewater and ground wastewater generated in the system operation process.

[0043] Further, the wastewater heat exchanger is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, and the cold material inlet of the wastewater heat exchanger is connected with the water outlet of the water storage tank.

[0044] Further, the wastewater stripping tower is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the wastewater stripping tower is connected with the cold material outlet of the wastewater heat exchanger, and the discharge outlet of the wastewater stripping tower is connected with the hot material inlet of the wastewater heat exchanger.

[0045] Further, the wastewater stripping tower condenser is provided with a feed inlet and a discharge outlet, the feed inlet of the wastewater stripping tower condenser is connected with the gas phase outlet of the wastewater stripping tower, and the discharge outlet of the wastewater stripping tower condenser is connected with the feed inlet of the recovery separator.

[0046] Further, the pretreatment reactor is provided with a water inlet and a water outlet, the water inlet of the pretreatment reactor is connected with the hot material outlet of the wastewater heat exchanger, and the water outlet of the pretreatment reactor is connected with a wastewater treatment device.

[0047] The utility model discloses the beneficial effects of the following:

[0048] 1, the system for producing polyvinyl chloride in the utility model includes vinyl chloride recovery unit and wastewater treatment unit, still sets up condenser in polymerization stripping unit, and the vinyl chloride produced in each link in the system is recycled, and the recycled vinyl chloride enters vinyl chloride recovery unit condensation recovery, continues to enter the polymerization stripping unit and reacts, on the basis of preventing pollution after vinyl chloride emission, the utilization of vinyl chloride is improved, and the production cost is saved.

[0049] 2, in the preparation process of polyvinyl chloride, the wastewater generated still includes unreacted vinyl chloride or other pollutants, the wastewater stripping tower and wastewater stripping tower condenser are used to the wastewater in the wastewater treatment unit and ground sewage together, the unreacted vinyl chloride is condensed and recycled into vinyl chloride recovery unit first, then the remaining wastewater is discharged after removing pollutants using the pretreatment reactor, in the treatment process of wastewater, the consumption of vinyl chloride is reduced.

[0050] 3、The system for producing polyvinyl chloride in the utility model is a combination of separate devices, when any device is damaged during the reaction process, the system is easy to maintain and replace, and the heat in the utility model can be recycled through the heat exchanger, and the recycled heat is used for heating other systems, the system for producing polyvinyl chloride in the utility model has a smooth preparation process and does not need manual intervention, and is an automatic device, thereby ensuring the safety of personnel. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 It is a structure diagram of the system for producing polyvinyl chloride in the utility model;

[0052] The names of the various reference numerals in the drawing are as follows: 2, an additive storage tank; 3, a fresh chloroethylene storage tank; 4, a recycled chloroethylene storage tank; 5, a polymerization kettle; 6, a kettle top condenser; 7, a discharge tank; 8, a stripping tower storage tank; 9, a polymerization heat exchanger; 10, a stripping tower; 11, a stripping tower condenser; 12, a mixing tank; 13, a recycling separator; 14, a compressor; 15, a primary condenser; 16, a secondary condenser; 17, a centrifugal machine; 18, a drying bed; 19, a cyclone separator; 20, a bag filter; 21, a condensing separator; 22, a water storage tank; 23, a waste water heat exchanger; 24, a waste water stripping tower; 25, a waste water stripping tower condenser; 26, a pretreatment reactor; 101, a normal-temperature desalted water tank; 102, a high-temperature desalted water tank; 103, a low-temperature desalted water tank; A, a storage configuration unit; B, a polymerization stripping unit; C, a chloroethylene recycling unit; D, a polyvinyl chloride drying and packaging unit; E, a waste water treatment unit. DETAILED DESCRIPTION

[0053] The utility model is described in detail in connection with the following examples:

[0054] The system for producing polyvinyl chloride provided by the utility model recycles by-products and unreacted chloroethylene in the reaction process, greatly improves the utilization rate of chloroethylene, and improves the environmental protection of the system.

[0055] Example 1

[0056] The system for producing polyvinyl chloride provided by the utility model recycles by-products and unreacted chloroethylene in the reaction process, greatly improves the utilization rate of chloroethylene, and improves the environmental protection of the system.

[0057] The storage configuration unit A includes a desalted water tank, an additive storage tank 2, a fresh chloroethylene storage tank 3 and a recycled chloroethylene storage tank 4;

[0058] The polymerization stripping unit B includes polymerization kettle 5, kettle top condenser 6, discharge tank 7, stripping tower storage tank 8, polymerization heat exchanger 9, stripping tower 10, stripping tower condenser 11 and mixing tank 12;

[0059] The vinyl chloride recovery unit C includes recovery separator 13, compressor 14, first stage condenser 15 and second stage condenser 16;

[0060] The polyvinyl chloride drying and packaging unit D includes centrifuge 17 and drying bed 18;

[0061] The waste water treatment unit E includes condensing separator 21, water storage tank 22, waste water heat exchanger 23, waste water stripping tower 24, waste water stripping tower condenser 25 and pretreatment reactor 26.

[0062] In the embodiment, the polyvinyl chloride drying and packaging unit D further includes cyclone separator 19 and bag filter 20;

[0063] The desalinated water tanks include normal temperature desalinated water tank 101, high temperature desalinated water tank 102 and low temperature desalinated water tank 103; the normal temperature desalinated water tank 101, the high temperature desalinated water tank 102 and the low temperature desalinated water tank 103 are provided with water inlet and water outlet; desalinated water enters the water inlets of the normal temperature desalinated water tank 101, the high temperature desalinated water tank 102 and the low temperature desalinated water tank 103 through pipelines; the low temperature desalinated water tank 103 and the high temperature desalinated water tank 102 are provided with heat exchangers for cooling and heating the desalinated water in the low temperature desalinated water tank 103 and the high temperature desalinated water tank 102;

[0064] The auxiliary agent storage tank 2 is provided with feed inlet and discharge outlet, and further provided with stirring device; the auxiliary agent in the auxiliary agent storage tank 2 includes initiator, dispersing agent and buffer; the initiator is t-butyl peroxy neodecanate and t-butyl peroxy neodecanate; the mass ratio of t-butyl peroxy neodecanate (BND) to polyvinyl chloride is 0.0003:1, and the mass ratio of t-butyl peroxy neodecanate (CND) to polyvinyl chloride is 0.0006:1; the dispersing agent is high alcoholysis degree polyvinyl alcohol (PVA-420H) and low alcoholysis degree polyvinyl alcohol (LM-10HD); the alcoholysis degree of the high alcoholysis degree polyvinyl alcohol is 78.5%, and the alcoholysis degree of the low alcoholysis degree polyvinyl alcohol is 40%; the mass ratio of the high alcoholysis degree polyvinyl alcohol to polyvinyl chloride is 0.0005:1, and the mass ratio of the low alcoholysis degree polyvinyl alcohol to polyvinyl chloride is 0.0002:1; the buffer is sodium bicarbonate, and the mass ratio of the sodium bicarbonate to the polyvinyl chloride is 0.0002:1;

[0065] The fresh vinyl chloride storage tank 3 is provided with feed inlet and discharge outlet;

[0066] The recovered vinyl chloride storage tank 4 is provided with a feed inlet and a discharge outlet;

[0067] The polymerization kettle 5 is provided with a hot desalted water inlet, a cold desalted water inlet, a feed inlet, a discharge outlet, a gas phase outlet and a water outlet, the hot desalted water inlet of the polymerization kettle 5 is connected with the water outlets of the normal temperature desalted water tank 101 and the high temperature desalted water tank 102, the cold desalted water inlet of the polymerization kettle 5 is connected with the water outlet of the low temperature desalted water tank 103, the feed inlet of the polymerization kettle 5 is connected with the discharge outlets of the fresh vinyl chloride storage tank 3 and the recovered vinyl chloride storage tank 4; the polymerization kettle 5 is provided with a stirring device; the outer layer of the polymerization kettle 5 is provided with a cooling water pipeline, and circulating cooling water is passed through the cooling water pipeline;

[0068] The kettle top condenser 6 is installed on the top of the polymerization kettle 5 to condense the materials reacted in the polymerization kettle 5;

[0069] The discharge tank 7 is provided with a feed inlet, a discharge outlet and a gas phase outlet, and the discharge tank 7 is also provided with a stirring device, and the feed inlet of the discharge tank 7 is connected with the discharge outlet of the polymerization kettle 5;

[0070] The stripping tower storage tank 8 is provided with a feed inlet, a discharge outlet and a gas phase outlet, and the stripping tower storage tank 8 is also provided with a stirring device, and the feed inlet of the stripping tower storage tank 8 is connected with the discharge outlet of the discharge tank 7;

[0071] The polymerization heat exchanger 9 is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, and the cold material inlet of the polymerization heat exchanger 9 is connected with the discharge outlet of the stripping tower storage tank 8;

[0072] The stripping tower 10 is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the stripping tower 10 is connected with the cold material outlet of the polymerization heat exchanger 9, and the discharge outlet of the stripping tower 10 is connected with the hot material inlet of the polymerization heat exchanger 9;

[0073] The stripping tower condenser 11 is provided with a gas phase inlet and a liquid outlet, and the gas phase inlet of the stripping tower condenser 11 is connected with the gas phase outlet of the stripping tower 10;

[0074] The mixing tank 12 is provided with a feed inlet and a discharge outlet, and the mixing tank 12 is also provided with a stirring device, and the feed inlet of the mixing tank 12 is connected with the hot material outlet of the polymerization heat exchanger 9;

[0075] The recovered separator 13 is provided with a feed inlet and a discharge outlet, and the feed inlet of the recovered separator 13 is connected with the gas phase outlets of the polymerization kettle 5, the discharge tank 7 and the stripping tower storage tank 8;

[0076] The compressor 14 is provided with an inlet and an outlet, and the inlet of the compressor 14 is connected with the outlet of the recovery separator 13;

[0077] The primary condenser 15 is provided with an inlet, an outlet and a gas phase outlet, the inlet of the primary condenser 15 is connected with the outlet of the compressor 14, and the outlet of the primary condenser 15 is connected with the inlet of the recovery vinyl chloride tank 4;

[0078] The secondary condenser 16 is provided with an inlet, an outlet and a gas phase outlet, the inlet of the secondary condenser 16 is connected with the gas phase outlet of the primary condenser 15, the outlet of the secondary condenser 16 is connected with the inlet of the recovery vinyl chloride tank 4, and the gas phase outlet of the secondary condenser 16 is connected with an exhaust treatment device;

[0079] The centrifuge 17 is provided with an inlet, an outlet and a waste water outlet, and the inlet of the centrifuge 17 is connected with the outlet of the mixing tank 12;

[0080] The drying bed 18 is provided with an inlet, an outlet and a gas outlet, and the inlet of the drying bed 18 is connected with the outlet of the centrifuge 17; the material is discharged from the outlet of the drying bed 18 and then packaged;

[0081] The cyclone separator 19 is provided with an inlet and an outlet, and the inlet of the cyclone separator 19 is connected with the gas outlet of the drying bed 18;

[0082] The bag filter 20 is provided with an inlet and an outlet, and the inlet of the bag filter 20 is connected with the outlet of the cyclone separator 19, and the outlet of the bag filter 20 is connected with an exhaust treatment device;

[0083] The condensing separator 21 is provided with a water inlet, a water outlet and a material outlet, and the water inlet of the condensing separator 21 is connected with the liquid outlet of the stripping column condenser 11, and the material outlet of the condensing separator 21 is connected with the inlet of the recovery separator 13;

[0084] Further, the water storage tank 22 is provided with a water inlet and a water outlet, the water inlet of the water storage tank 22 is connected with the water outlet of the condensing separator 21, and the water inlet of the water storage tank 22 is also connected with the waste water outlet of the centrifuge 17 and the water outlet of the polymerization kettle 5; the water storage tank 22 also contains flushing waste water and ground waste water during the system operation;

[0085] The waste water heat exchanger 23 is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, and the cold material inlet of the waste water heat exchanger 23 is connected with the water outlet of the water storage tank 22;

[0086] The wastewater stripping column 24 is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the wastewater stripping column 24 is connected with the cold material outlet of the wastewater heat exchanger 23, and the discharge outlet of the wastewater stripping column 24 is connected with the hot material inlet of the wastewater heat exchanger 23;

[0087] The wastewater stripping column condenser 25 is provided with a feed inlet and a discharge outlet, the feed inlet of the wastewater stripping column condenser 25 is connected with the gas phase outlet of the wastewater stripping column 24, and the discharge outlet of the wastewater stripping column condenser 25 is connected with the feed inlet of the recovery separator 13;

[0088] The pretreatment reactor 26 is provided with a water inlet and a water outlet, the water inlet of the pretreatment reactor 26 is connected with the hot material outlet of the wastewater heat exchanger 23, and the water outlet of the pretreatment reactor 26 is connected with a wastewater treatment device.

[0089] The embodiment also provides a method for preparing polyvinyl chloride by using the system for producing polyvinyl chloride, comprising the following steps:

[0090] Step 1, material storage configuration

[0091] Desalted water enters the normal-temperature desalted water tank 101, the high-temperature desalted water tank 102 and the low-temperature desalted water tank 103 through a pipeline, a heat exchanger with a temperature of 0.3 MPa and 180℃ is used to heat the desalted water in the high-temperature desalted water tank 102, and a heat exchanger is used to cool the desalted water in the low-temperature desalted water tank 103, so as to obtain high-temperature desalted water with a temperature of 90℃ and low-temperature desalted water with a temperature of 23℃, and the temperature of the normal-temperature desalted water in the normal-temperature desalted water tank 101 is 30℃;

[0092] Step 2, polymer stripping

[0093] In the polymerization kettle 5, a layer of oleophobic hydrophilic polymer with a spraying thickness of 2.5 nm is sprayed by using a steam method, 49.5 m 3 Fresh chloroethylene enters the polymerization kettle 5 from the fresh chloroethylene storage tank 3, and at the same time, 58.41 m 3 / min of the normal-temperature desalted water, the high-temperature desalted water and the low-temperature desalted water are added at a rate of 5 m 3, to the reaction starting temperature is 56.8℃, and the auxiliary tank 2 in the auxiliary together into the polymerizer 5, stirring at 90r / min, the reaction time is 240min, the reaction process continuously through the low temperature desalted water to the polymerizer 5 is cooled and sealed, the polymerizer 5 outer layer of cooling water pipeline through 30℃ circulating water to the polymerizer 5 is cooled, the reaction process in the polymerizer 5 material due to temperature rise and evaporation, evaporated material encounter the polymerizer 5 top of the kettle top condenser 6 condensation, again fall into the polymerizer 5 repeatedly reaction, the reaction process produces unreacted vinyl chloride and other impurities gas from the polymerizer 5 into the recovery separator 13, the polymerizer 5 in the waste water into the water storage tank 22;

[0094] The material in the polymerizer 5 after the reaction generated into the discharge tank 7, in the discharge tank 7 generated part of the unreacted vinyl chloride into the recovery separator 13, the material from the discharge tank 7 into the stripping tower storage tank 8, the material in the stripping tower storage tank 8 by polymer heat exchanger 9 into the absorption of heat after entering the stripping tower 10 stripping, the stripping tower 10 top temperature is 95℃, the bottom temperature is 105℃, in the stripping tower 10, part of the unreacted vinyl chloride via stripping tower condenser 11 into the condensation separator 21, and the stripping of the material from the stripping tower 10 bottom into the polymer heat exchanger 9 heat recovery, again into the mixing tank 12;

[0095] Step 3, vinyl chloride recovery

[0096] The vinyl chloride in the recovery separator 13 is compressed into the first condenser 15 by the compressor 14. The liquid vinyl chloride condensed in the first condenser 15 enters the recovered vinyl chloride storage tank 4, and the gas that is not condensed enters the second condenser 16 for condensation. The liquid vinyl chloride condensed in the second condenser 16 enters the recovered vinyl chloride storage tank 4, and the gas that is not condensed is discharged after removing pollutants in the tail gas treatment device. The vinyl chloride in the recovered vinyl chloride storage tank 4 enters the polymerizer 5 with the vinyl chloride in the fresh vinyl chloride tank 3;

[0097] Step 4, PVC recovery and packaging

[0098] The material in the mixing tank 12 is separated by centrifuge 17, and the solid material enters the drying bed 18. After drying at 95℃ in the drying bed 18, PVC is obtained. The PVC output from the drying bed 18 is packaged, and the liquid water produced in the centrifuge 17 enters the water storage tank 22. The gas material dried in the drying bed 18 is sequentially introduced into the cyclone separator 19 and the bag filter 20 for separation;

[0099] Step 5, waste water treatment

[0100] The condensed liquid in the condensing separator 21 enters the water storage tank 22, and the gaseous vinyl chloride enters the recovery separator 13. The water storage tank 22 contains waste water from the polymerization kettle 5, waste water from washing the floor during production, and waste liquid from the centrifuge 17. All the waste water in the water storage tank 22 is stripped in the waste water stripping column 24 after absorbing heat via the waste water heat exchanger 23. The overhead temperature of the waste water stripping column is 75°C, and the bottom temperature is 85°C. The stripped material enters the pretreatment reactor 26 after recovering heat from the waste water heat exchanger 23, and then enters the waste water treatment device. The gas produced in the waste water stripping column 24 is condensed in the waste water stripping column condenser 25 and then enters the recovery separator 13.

[0101] In this embodiment, the pH value of the waste water is 7.4, the COD is 439 mg / L, the BOD is 174 mg / L, and the SS is 82 mg / L.

[0102] The PVC has a viscosity number of 110 ml / g, an impurity particle number of 14, a volatile content of 0.29%, and an apparent density of 0.485 g / ml.

[0103] Embodiment 2

[0104] The system for producing PVC provided in this embodiment includes a storage and configuration unit A, a polymerization and stripping unit B, a vinyl chloride recovery unit C, a PVC drying and packaging unit D, and a waste water treatment unit E, according to the direction of material transportation.

[0105] The storage and configuration unit A includes a desalted water tank, an additive storage tank 2, a fresh vinyl chloride storage tank 3, and a recovered vinyl chloride storage tank 4.

[0106] The polymerization and stripping unit B includes a polymerization kettle 5, a kettle top condenser 6, a discharge tank 7, a stripping column storage tank 8, a polymerization heat exchanger 9, a stripping column 10, a stripping column condenser 11, and a mixing tank 12.

[0107] The vinyl chloride recovery unit C includes a recovery separator 13, a compressor 14, a primary condenser 15, and a secondary condenser 16.

[0108] The PVC drying and packaging unit D includes a centrifuge 17 and a drying bed 18.

[0109] The waste water treatment unit E includes a condensing separator 21, a water storage tank 22, a waste water heat exchanger 23, a waste water stripping column 24, a waste water stripping column condenser 25, and a pretreatment reactor 26.

[0110] In this embodiment, the PVC drying and packaging unit D also includes a cyclone separator 19 and a bag filter 20.

[0111] The desalted water tank comprises a normal-temperature desalted water tank 101, a high-temperature desalted water tank 102 and a low-temperature desalted water tank 103; the normal-temperature desalted water tank 101, the high-temperature desalted water tank 102 and the low-temperature desalted water tank 103 are provided with water inlets and water outlets; desalted water enters the normal-temperature desalted water tank 101, the high-temperature desalted water tank 102 and the low-temperature desalted water tank 103 through the water inlets; the low-temperature desalted water tank 103 and the high-temperature desalted water tank 102 are provided with heat exchangers for cooling and heating the desalted water in the low-temperature desalted water tank 103 and the high-temperature desalted water tank 102;

[0112] The auxiliary agent storage tank 2 is provided with a feeding port and a discharging port, and is further provided with a stirring device; the auxiliary agent in the auxiliary agent storage tank 2 comprises an initiator, a dispersing agent and a buffer agent; the initiator is t-butyl peroxyneodecanoate and t-butyl peroxyneodecanoate; the mass ratio of the t-butyl peroxyneodecanoate (BND) to polyvinyl chloride is 0.0003:1, and the mass ratio of the t-butyl peroxyneodecanoate (CND) to polyvinyl chloride is 0.0006:1; the dispersing agent is high-alcoholysis-degree polyvinyl alcohol (PVA-420H) and low-alcoholysis-degree polyvinyl alcohol (LM-10HD); the alcoholysis degree of the high-alcoholysis-degree polyvinyl alcohol is 81.5%, and the alcoholysis degree of the low-alcoholysis-degree polyvinyl alcohol is 45%; the mass ratio of the high-alcoholysis-degree polyvinyl alcohol to polyvinyl chloride is 0.0005:1, and the mass ratio of the low-alcoholysis-degree polyvinyl alcohol to polyvinyl chloride is 0.0002:1; the buffer agent is sodium bicarbonate, and the mass ratio of the sodium bicarbonate to polyvinyl chloride is 0.0002:1;

[0113] The fresh chloroethylene storage tank 3 is provided with a feeding port and a discharging port;

[0114] The recycled chloroethylene storage tank 4 is provided with a feeding port and a discharging port;

[0115] The polymerization kettle 5 is provided with a hot desalted water inlet, a cold desalted water inlet, a feeding port, a discharging port, a gas phase outlet and a water outlet; the hot desalted water inlet of the polymerization kettle 5 is connected with the water outlets of the normal-temperature desalted water tank 101 and the high-temperature desalted water tank 102; the cold desalted water inlet of the polymerization kettle 5 is connected with the water outlet of the low-temperature desalted water tank 103; the feeding port of the polymerization kettle 5 is connected with the discharging ports of the fresh chloroethylene storage tank 3 and the recycled chloroethylene storage tank 4; the polymerization kettle 5 is provided with a stirring device; the outer layer of the polymerization kettle 5 is provided with a cooling water pipeline, and circulating cooling water flows through the cooling water pipeline;

[0116] The kettle top condenser 6 is arranged on the top of the polymerization kettle 5, and condenses the materials reacted in the polymerization kettle 5;

[0117] The discharge tank 7 is provided with a feed port, a discharge port and a gas phase outlet, and a stirring device is also provided in the discharge tank 7. The feed port of the discharge tank 7 is connected to the discharge port of the polymerization kettle 5;

[0118] The stripping tower storage tank 8 is provided with a feed port, a discharge port and a gas phase outlet. The stripping tower storage tank 8 is also provided with a stirring device. The feed port of the stripping tower storage tank 8 is connected to the discharge port of the discharge tank 7;

[0119] The polymerization heat exchanger 9 is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, and the cold material inlet of the polymerization heat exchanger 9 is connected to the discharge port of the stripping tower storage tank 8;

[0120] The stripping tower 10 is provided with a feed port, a discharge port and a gas phase outlet. The feed port of the stripping tower 10 is connected to the cold material outlet of the polymerization heat exchanger 9, and the discharge port of the stripping tower 10 is connected to the hot material inlet of the polymerization heat exchanger 9;

[0121] The stripping tower condenser 11 is provided with a gas phase inlet and a liquid outlet, and the gas phase inlet of the stripping tower condenser 11 is connected to the gas phase outlet of the stripping tower 10;

[0122] The mixing tank 12 is provided with a feed port and a discharge port, and a stirring device is also provided in the mixing tank 12. The feed port of the mixing tank 12 is connected to the hot material outlet of the polymerization heat exchanger 9;

[0123] The recovery separator 13 is provided with a feed port and a discharge port, and the feed port of the recovery separator 13 is connected to the discharge tank 7 of the polymerization kettle 5 and the gas phase outlet of the stripping tower storage tank 8;

[0124] The compressor 14 is provided with a feed port and a discharge port, and the feed port of the compressor 14 is connected to the discharge port of the recovery separator 13;

[0125] The primary condenser 15 is provided with a feed port, a discharge port and a gas phase outlet. The feed port of the primary condenser 15 is connected to the discharge port of the compressor 14, and the discharge port of the primary condenser 15 is connected to the feed port of the recovered vinyl chloride storage tank 4;

[0126] The secondary condenser 16 is provided with a feed port, a discharge port and a gas phase outlet. The feed port of the secondary condenser 16 is connected to the gas phase outlet of the primary condenser 15, the discharge port of the secondary condenser 16 is connected to the feed port of the recovered vinyl chloride storage tank 4, and the gas phase outlet of the secondary condenser 16 is connected to the tail gas treatment device;

[0127] The centrifuge 17 is provided with a feed inlet, a discharge outlet and a waste water outlet, the feed inlet of the centrifuge 17 is connected with the discharge outlet of the mixing tank 12;

[0128] The drying bed 18 is provided with a feed inlet, a discharge outlet and a gas outlet, the feed inlet of the drying bed 18 is connected with the discharge outlet of the centrifuge 17; the material is discharged from the discharge outlet of the drying bed 18 and then packaged;

[0129] The cyclone separator 19 is provided with a feed inlet and a discharge outlet, the feed inlet of the cyclone separator 19 is connected with the gas outlet of the drying bed 18;

[0130] The bag filter 20 is provided with a feed inlet and a gas outlet, the feed inlet of the bag filter 20 is connected with the discharge outlet of the cyclone separator 19, and the gas outlet of the bag filter 20 is connected with the tail gas treatment device;

[0131] The condensing separator 21 is provided with a water inlet, a water outlet and a material outlet, the water inlet of the condensing separator 21 is connected with the liquid outlet of the stripping tower condenser 11, and the material outlet of the condensing separator 21 is connected with the feed inlet of the recovery separator 13;

[0132] Further, the water storage tank 22 is provided with a water inlet and a water outlet, the water inlet of the water storage tank 22 is connected with the water outlet of the condensing separator 21, and the water inlet of the water storage tank 22 is also connected with the waste water outlet of the centrifuge 17 and the water outlet of the polymerization kettle 5; the water storage tank 22 also contains flushing waste water and ground waste water in the system working process;

[0133] The waste water heat exchanger 23 is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, the cold material inlet of the waste water heat exchanger 23 is connected with the water outlet of the water storage tank 22;

[0134] The waste water stripping tower 24 is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the waste water stripping tower 24 is connected with the cold material outlet of the waste water heat exchanger 23, and the discharge outlet of the waste water stripping tower 24 is connected with the hot material inlet of the waste water heat exchanger 23;

[0135] The waste water stripping tower condenser 25 is provided with a feed inlet and a discharge outlet, the feed inlet of the waste water stripping tower condenser 25 is connected with the gas phase outlet of the waste water stripping tower 24, and the discharge outlet of the waste water stripping tower condenser 25 is connected with the feed inlet of the recovery separator 13;

[0136] The pretreatment reactor 26 is provided with a water inlet and a water outlet, the water inlet of the pretreatment reactor 26 is connected with the hot material outlet of the wastewater heat exchanger 23, and the water outlet of the pretreatment reactor 26 is connected with a wastewater treatment device.

[0137] The embodiment also provides a method for preparing polyvinyl chloride by using the system for producing polyvinyl chloride, comprising the following steps:

[0138] Step 1, material storage configuration

[0139] Desalted water enters a normal-temperature desalted water tank 101, a high-temperature desalted water tank 102 and a low-temperature desalted water tank 103 through a pipeline, a heat exchanger with a pressure of 0.4 MPa and a temperature of 200 DEG C is used to heat the desalted water in the high-temperature desalted water tank 102, and a heat exchanger is used to cool the desalted water in the low-temperature desalted water tank 103, so that high-temperature desalted water with a temperature of 95 DEG C and low-temperature desalted water with a temperature of 25 DEG C are obtained, and the temperature of the normal-temperature desalted water in the normal-temperature desalted water tank 101 is 35 DEG C;

[0140] Step 2, polymerization stripping

[0141] In the polymerization kettle 5, a layer of oil-repellent and water-repellent polymer with a spraying thickness of 1 nm is sprayed by using a steam method, 49.5 m 3 Fresh chloroethylene enters the polymerization kettle 5 from a fresh chloroethylene storage tank 3, at the same time, 57 m 3 / min of the normal-temperature desalted water, the high-temperature desalted water and the low-temperature desalted water are added into the polymerization kettle 5 at a rate of 5 m 3 / min, the reaction starting temperature is 56.8 DEG C, and the auxiliary agent in the auxiliary agent storage tank 2 enters the polymerization kettle 5 together, the reaction is carried out under stirring at 120 r / min, the reaction time is 280 min, the low-temperature desalted water is continuously used to cool and seal the polymerization kettle 5 during the reaction, 40 DEG C circulating water in the cooling water pipeline outside the polymerization kettle 5 is used to cool the polymerization kettle 5, and the materials in the polymerization kettle 5 evaporate due to temperature rise during the reaction, the evaporated materials are condensed by a kettle top condenser 6 at the top of the polymerization kettle 5, and then fall back into the polymerization kettle 5 to repeatedly react, the unreacted chloroethylene and other impurity gases generated during the reaction enter a recovery separator 13 from the polymerization kettle 5, and the wastewater in the polymerization kettle 5 is discharged into a water storage tank 22;

[0142] The material produced after the reaction in the polymerizer 5 enters the discharge tank 7, and part of the unreacted vinyl chloride produced in the discharge tank 7 enters the recovery separator 13. The material in the discharge tank 7 enters the stripping tower storage tank 8, and the material in the stripping tower storage tank 8 enters the polymerization heat exchanger 9, absorbs heat, and then enters the stripping tower 10 for stripping. The overhead temperature of the stripping tower 10 is 90°C, and the bottom temperature is 100°C. In the stripping tower 10, part of the unreacted vinyl chloride is produced and enters the condensation separator 21 through the stripping tower condenser 11, and the stripped material enters the polymerization heat exchanger 9 from the bottom of the stripping tower 10 to recover heat and then enters the mixing tank 12.

[0143] Step 3, vinyl chloride recovery

[0144] The vinyl chloride in the recovery separator 13 is compressed by the compressor 14 and enters the primary condenser 15. The liquid vinyl chloride condensed in the primary condenser 15 enters the recovered vinyl chloride storage tank 4, and the gas that is not condensed enters the secondary condenser 16 for condensation. The liquid vinyl chloride condensed in the secondary condenser 16 enters the recovered vinyl chloride storage tank 4, and the gas that is not condensed is removed after being treated by the tail gas treatment device and then discharged. The vinyl chloride in the recovered vinyl chloride storage tank 4 enters the polymerizer 5 with the vinyl chloride in the fresh vinyl chloride tank 3.

[0145] Step 4, PVC recovery and packaging

[0146] The material in the mixing tank 12 is separated by the centrifuge 17, and the solid material enters the drying bed 18. After drying at 100°C in the drying bed 18, PVC is obtained. The PVC output from the drying bed 18 is packaged, and the liquid water produced in the centrifuge 17 enters the water storage tank 22. The gaseous material dried in the drying bed 18 is sequentially introduced into the cyclone separator 19 and the bag filter 20 for separation.

[0147] Step 5, wastewater treatment

[0148] The liquid condensed in the condensation separator 21 enters the water storage tank 22, and the gaseous vinyl chloride enters the recovery separator 13. The water storage tank 22 includes the wastewater from the polymerizer 5, the wastewater from the floor washing during production, and the wastewater from the centrifuge 17. All the wastewater in the water storage tank 22 is heated by the wastewater heat exchanger 23 and then enters the wastewater stripping tower 24 for stripping. The overhead temperature of the wastewater stripping tower is 75°C, and the bottom temperature is 85°C. The stripped material is heated by the wastewater heat exchanger 23 and then enters the pretreatment reactor 26 and then enters the wastewater treatment device. The gas produced in the wastewater stripping tower 24 is condensed by the wastewater stripping tower condenser 25 and then enters the recovery separator 13.

[0149] In this embodiment, the pH value of the wastewater is 7.1, the COD is 408 mg / L, the BOD is 160 mg / L, and the SS is 90 mg / L.

[0150] The polyvinyl chloride has a viscosity number of 108 ml / g, an impurity particle number of 14, a volatile content of 0.31%, and an apparent density of 0.48 g / ml.

[0151] Embodiment 3

[0152] The system for producing polyvinyl chloride comprises a storage and configuration unit A, a polymerization and stripping unit B, a vinyl chloride recovery unit C, a polyvinyl chloride drying and packaging unit D, and a wastewater treatment unit E according to the direction of material transportation.

[0153] The storage and configuration unit A comprises a desalted water tank, an additive storage tank 2, a fresh vinyl chloride storage tank 3, and a recovered vinyl chloride storage tank 4.

[0154] The polymerization and stripping unit B comprises a polymerization kettle 5, a kettle top condenser 6, a discharge tank 7, a stripping tower storage tank 8, a polymerization heat exchanger 9, a stripping tower 10, a stripping tower condenser 11, and a mixing tank 12.

[0155] The vinyl chloride recovery unit C comprises a recovery separator 13, a compressor 14, a first-stage condenser 15, and a second-stage condenser 16.

[0156] The polyvinyl chloride drying and packaging unit D comprises a centrifuge 17 and a drying bed 18.

[0157] The wastewater treatment unit E comprises a condensation separator 21, a water storage tank 22, a wastewater heat exchanger 23, a wastewater stripping tower 24, a wastewater stripping tower condenser 25, and a pretreatment reactor 26.

[0158] In this embodiment, the polyvinyl chloride drying and packaging unit D further comprises a cyclone separator 19 and a bag filter 20.

[0159] The desalted water tank comprises a normal-temperature desalted water tank 101, a high-temperature desalted water tank 102, and a low-temperature desalted water tank 103. The normal-temperature desalted water tank 101, the high-temperature desalted water tank 102, and the low-temperature desalted water tank 103 are each provided with a water inlet and a water outlet. Desalted water enters the water inlets of the normal-temperature desalted water tank 101, the high-temperature desalted water tank 102, and the low-temperature desalted water tank 103 through pipelines. The low-temperature desalted water tank 103 and the high-temperature desalted water tank 102 are each provided with a heat exchanger for cooling and heating the desalted water in the low-temperature desalted water tank 103 and the high-temperature desalted water tank 102.

[0160] The auxiliary agent storage tank 2 is provided with a feeding port and a discharging port, and is also provided with a stirring device; the auxiliary agent in the auxiliary agent storage tank 2 includes an initiator, a dispersing agent and a buffer; the initiator is t-butyl peroxyneodecanoate and t-butyl peroxyneodecanoate; the mass ratio of the t-butyl peroxyneodecanoate (BND) to polyvinyl chloride is 0.0007:1, and the mass ratio of the t-butyl peroxyneodecanoate (CND) to polyvinyl chloride is 0.0011:1; the dispersing agent is high-alcoholysis-degree polyvinyl alcohol (PVA-420H) and low-alcoholysis-degree polyvinyl alcohol (LM-10HD); the alcoholysis degree of the high-alcoholysis-degree polyvinyl alcohol is 78.5%, and the alcoholysis degree of the low-alcoholysis-degree polyvinyl alcohol is 40%; the mass ratio of the high-alcoholysis-degree polyvinyl alcohol to polyvinyl chloride is 0.001:1, and the mass ratio of the low-alcoholysis-degree polyvinyl alcohol to polyvinyl chloride is 0.0006:1; the buffer is sodium bicarbonate, and the mass ratio of the sodium bicarbonate to the polyvinyl chloride is 0.0005:1;

[0161] The fresh chloroethylene storage tank 3 is provided with a feeding port and a discharging port;

[0162] The recycled chloroethylene storage tank 4 is provided with a feeding port and a discharging port;

[0163] The polymerization kettle 5 is provided with a hot desalted water inlet, a cold desalted water inlet, a feeding port, a discharging port, a gas phase outlet and a water outlet, the hot desalted water inlet of the polymerization kettle 5 is connected with the water outlets of the normal-temperature desalted water tank 101 and the high-temperature desalted water tank 102, the cold desalted water inlet of the polymerization kettle 5 is connected with the water outlet of the low-temperature desalted water tank 103, and the feeding port of the polymerization kettle 5 is connected with the discharging ports of the fresh chloroethylene storage tank 3 and the recycled chloroethylene storage tank 4; the polymerization kettle 5 is provided with a stirring device; the outer layer of the polymerization kettle 5 is provided with a cooling water pipeline, and circulating cooling water is circulated in the cooling water pipeline;

[0164] The kettle top condenser 6 is installed on the top of the polymerization kettle 5, and condenses the materials reacted in the polymerization kettle 5;

[0165] The discharging tank 7 is provided with a feeding port, a discharging port and a gas phase outlet, and is also provided with a stirring device, and the feeding port of the discharging tank 7 is connected with the discharging port of the polymerization kettle 5;

[0166] The stripping tower storage tank 8 is provided with a feeding port, a discharging port and a gas phase outlet, and is also provided with a stirring device, and the feeding port of the stripping tower storage tank 8 is connected with the discharging port of the discharging tank 7;

[0167] The polymerization heat exchanger 9 is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, and the cold material inlet of the polymerization heat exchanger 9 is connected with the discharging port of the stripping tower storage tank 8.

[0168] The stripping column 10 is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the stripping column 10 is connected with the cold material outlet of the polymerization heat exchanger 9, and the discharge outlet of the stripping column 10 is connected with the hot material inlet of the polymerization heat exchanger 9;

[0169] The stripping column condenser 11 is provided with a gas phase inlet and a liquid outlet, the gas phase inlet of the stripping column condenser 11 is connected with the gas phase outlet of the stripping column 10;

[0170] The mixing tank 12 is provided with a feed inlet and a discharge outlet, and is further provided with a stirring device, the feed inlet of the mixing tank 12 is connected with the hot material outlet of the polymerization heat exchanger 9;

[0171] The recovery separator 13 is provided with a feed inlet and a discharge outlet, the feed inlet of the recovery separator 13 is connected with the gas phase outlets of the polymerization kettle 5, the discharge tank 7 and the stripping column storage tank 8;

[0172] The compressor 14 is provided with a feed inlet and a discharge outlet, the feed inlet of the compressor 14 is connected with the discharge outlet of the recovery separator 13;

[0173] The primary condenser 15 is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the primary condenser 15 is connected with the discharge outlet of the compressor 14, and the discharge outlet of the primary condenser 15 is connected with the feed inlet of the recovered chloroethylene storage tank 4;

[0174] The secondary condenser 16 is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the secondary condenser 16 is connected with the gas phase outlet of the primary condenser 15, the discharge outlet of the secondary condenser 16 is connected with the feed inlet of the recovered chloroethylene storage tank 4, and the gas phase outlet of the secondary condenser 16 is connected with a tail gas treatment device;

[0175] The centrifuge 17 is provided with a feed inlet, a discharge outlet and a waste water outlet, the feed inlet of the centrifuge 17 is connected with the discharge outlet of the mixing tank 12;

[0176] The drying bed 18 is provided with a feed inlet, a discharge outlet and a gas outlet, the feed inlet of the drying bed 18 is connected with the discharge outlet of the centrifuge 17, and the material is discharged from the discharge outlet of the drying bed 18 for packaging;

[0177] The cyclone separator 19 is provided with a feed inlet and a discharge outlet, the feed inlet of the cyclone separator 19 is connected with the gas outlet of the drying bed 18;

[0178] The bag filter 20 is provided with a feed inlet and a gas outlet, the feed inlet of the bag filter 20 is connected with the discharge outlet of the cyclone separator 19, and the gas outlet of the bag filter 20 is connected with the tail gas treatment device;

[0179] The condensing separator 21 is provided with a water inlet, a water outlet and a material outlet, the water inlet of the condensing separator 21 is connected with the liquid outlet of the stripping tower condenser 11, and the material outlet of the condensing separator 21 is connected with the feed inlet of the recovery separator 13;

[0180] Further, the water storage tank 22 is provided with a water inlet and a water outlet, the water inlet of the water storage tank 22 is connected with the water outlet of the condensing separator 21, and the water inlet of the water storage tank 22 is also connected with the waste water outlet of the centrifuge 17 and the water outlet of the polymerization kettle 5; the water storage tank 22 is also filled with flushing waste water and ground waste water in the system working process;

[0181] The waste water heat exchanger 23 is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, the cold material inlet of the waste water heat exchanger 23 is connected with the water outlet of the water storage tank 22;

[0182] The waste water stripping tower 24 is provided with a feed inlet, a discharge outlet and a gas phase outlet, the feed inlet of the waste water stripping tower 24 is connected with the cold material outlet of the waste water heat exchanger 23, and the discharge outlet of the waste water stripping tower 24 is connected with the hot material inlet of the waste water heat exchanger 23;

[0183] The waste water stripping tower condenser 25 is provided with a feed inlet and a discharge outlet, the feed inlet of the waste water stripping tower condenser 25 is connected with the gas phase outlet of the waste water stripping tower 24, and the discharge outlet of the waste water stripping tower condenser 25 is connected with the feed inlet of the recovery separator 13;

[0184] The pretreatment reactor 26 is provided with a water inlet and a water outlet, the water inlet of the pretreatment reactor 26 is connected with the hot material outlet of the waste water heat exchanger 23, and the water outlet of the pretreatment reactor 26 is connected with a waste water treatment device.

[0185] The embodiment also provides a method for preparing polyvinyl chloride by using the system for producing polyvinyl chloride, comprising the following steps:

[0186] Step 1, material storage configuration

[0187] Desalted water from the pipeline into the normal temperature desalted water tank 101, high temperature desalted water tank 102 and low temperature desalted water tank 103, using 0.4 MPa, 180 ℃ heat exchanger for the heating of desalted water in the high temperature desalted water tank 102, and heat exchanger for the cooling of desalted water in the low temperature desalted water tank 103, get 95 ℃ high temperature desalted water and 25 ℃ low temperature desalted water, the temperature of the normal temperature desalted water tank 101 in the normal temperature desalted water is 30 ℃;

[0188] Step 2, polymerization stripping

[0189] In the polymerization kettle 5 using steam method spraying thickness of 3 nm of a layer of oil-repellent hydrophilic polymer, 49.5 m 3 Fresh vinyl chloride from fresh vinyl chloride storage tank 3 into the polymerization kettle 5, while, 5 m 3 / min rate of normal temperature desalted water, high temperature desalted water and low temperature desalted water 59.4 m 3 , to the reaction starting temperature is 56.8 ℃, and the auxiliary storage tank 2 in the auxiliary together into the polymerization kettle 5, stirring at 90 r / min, the reaction time is 300 min, the reaction process continues to pass the low temperature desalted water to the polymerization kettle 5 cooling and sealing, the polymerization kettle 5 outer cooling water pipeline in the polymerization kettle 5 cooling with 30 ℃ circulating water, the material in the polymerization kettle 5 due to temperature rise and evaporation, evaporation of the material into the kettle top condenser 6 on the top of the polymerization kettle 5 condensation, and fall back into the polymerization kettle 5 repeatedly for reaction, the reaction process produces unreacted vinyl chloride and other impurities gas from the polymerization kettle 5 into the recovery separator 13, the waste water in the polymerization kettle 5 into the water storage tank 22;

[0190] The material in the polymerization kettle 5 after the reaction into the discharge tank 7, in the discharge tank 7 generated part of the unreacted vinyl chloride into the recovery separator 13, the material from the discharge tank 7 into the stripping tower storage tank 8, the material in the stripping tower storage tank 8 by polymerization heat exchanger 9 into the absorption of heat into the stripping tower 10 stripping, the stripping tower 10 top temperature is 95 ℃, the bottom temperature is 105 ℃, in the stripping tower 10, part of the unreacted vinyl chloride generated by the stripping tower condenser 11 into the condensation separator 21, and the stripping of the material from the bottom of the stripping tower 10 into the polymerization heat exchanger 9 heat recovery, and then into the mixing tank 12;

[0191] Step 3, vinyl chloride recovery

[0192] The vinyl chloride in the recovery separator 13 is compressed by the compressor 14 and enters the first condenser 15. The condensed liquid vinyl chloride enters the recovery vinyl chloride tank 4, and the gas that is not condensed enters the second condenser 16. The condensed liquid vinyl chloride enters the recovery vinyl chloride tank 4, and the gas that is not condensed enters the tail gas treatment device to remove pollutants and is discharged. The vinyl chloride in the recovery vinyl chloride tank 4 enters the polymerization kettle 5 with the vinyl chloride in the fresh vinyl chloride tank 3.

[0193] Step 4, PVC recovery packaging

[0194] The material in the mixing tank 12 is centrifuged by the centrifuge 17. The solid material enters the drying bed 18, and the PVC is obtained after drying at 95°C in the drying bed 18. The PVC is packaged after being output from the drying bed 18. The liquid water produced in the centrifuge 17 enters the water storage tank 22. The gaseous material dried in the drying bed 18 is sequentially introduced into the cyclone separator 19 and the bag filter 20 for separation.

[0195] Step 5, waste water treatment

[0196] The liquid condensed in the condensation separator 21 enters the water storage tank 22, and the gaseous vinyl chloride enters the recovery separator 13. The water storage tank 22 includes the waste water in the polymerization kettle 5, the waste water for flushing the floor during production, and the waste liquid in the centrifuge 17. All the waste water in the water storage tank 22 is heated by the waste water heat exchanger 23 and then enters the waste water stripping tower 24 for stripping. The overhead temperature of the waste water stripping tower is 70°C, and the bottom temperature is 80°C. The stripped material is heated by the waste water heat exchanger 23 and then enters the pretreatment reactor 26, and then enters the waste water treatment device. The gas produced in the waste water stripping tower 24 is condensed by the waste water stripping tower condenser 25 and then enters the recovery separator 13.

[0197] In this embodiment, the pH value of the waste water is 6.6, the COD is 452 mg / L, the BOD is 191 mg / L, and the SS is 88 mg / L.

[0198] The PVC has a viscosity number of 116 ml / g, an impurity particle number of 15, a volatile content of 0.37%, and an apparent density of 0.489 g / ml.

[0199] Table 1 shows the properties of the waste water and PVC in Examples 1-3.

[0200]

[0201] The system for producing polyvinyl chloride has wide application range, low cost and high market prospect.

[0202] The above is only the preferred embodiment of the present application, and is not intended to limit the present application in any other form, and any modification or equivalent change made according to the technical essence of the present application still falls within the scope of the present application.

Claims

1. A system for producing polyvinyl chloride, characterized by, According to the material transportation direction, the system comprises a storage configuration unit (A), a polymerization stripping unit (B), a vinyl chloride recovery unit (C), a PVC drying and packaging unit (D) and a wastewater treatment unit (E); The storage configuration unit (A) comprises a desalted water tank, an additive storage tank (2), a fresh vinyl chloride storage tank (3) and a recovered vinyl chloride storage tank (4); The polymerization stripping unit (B) comprises a polymerization kettle (5), a kettle top condenser (6), a discharge tank (7), a stripping tower storage tank (8), a polymerization heat exchanger (9), a stripping tower (10), a stripping tower condenser (11) and a mixing tank (12); The vinyl chloride recovery unit (C) comprises a recovery separator (13), a compressor (14), a first-stage condenser (15) and a second-stage condenser (16); The PVC drying and packaging unit (D) comprises a centrifugal machine (17) and a drying bed (18); The wastewater treatment unit (E) comprises a condensation separator (21), a water storage tank (22), a wastewater heat exchanger (23), a wastewater stripping tower (24), a wastewater stripping tower condenser (25) and a pretreatment reactor (26).

2. The system of claim 1, wherein, The PVC drying and packaging unit (D) further comprises a cyclone separator (19) and a bag filter (20).

3. The system of claim 1, wherein, The desalted water tank comprises a normal-temperature desalted water tank (101), a high-temperature desalted water tank (102) and a low-temperature desalted water tank (103); The normal-temperature desalted water tank (101), the high-temperature desalted water tank (102) and the low-temperature desalted water tank (103) are each provided with a water inlet and a water outlet; Desalted water enters the water inlets of the normal-temperature desalted water tank (101), the high-temperature desalted water tank (102) and the low-temperature desalted water tank (103) through pipelines; The low-temperature desalted water tank (103) and the high-temperature desalted water tank (102) are each provided with a heat exchanger for cooling and heating the desalted water in the low-temperature desalted water tank (103) and the high-temperature desalted water tank (102).

4. The system of claim 3, wherein, The polymerization kettle (5) is provided with a hot desalted water inlet, a cold desalted water inlet, a feed inlet, a discharge outlet, a gas phase outlet and a water outlet, the hot desalted water inlet of the polymerization kettle (5) is connected with the water outlets of the normal-temperature desalted water tank (101) and the high-temperature desalted water tank (102), the cold desalted water inlet of the polymerization kettle (5) is connected with the water outlet of the low-temperature desalted water tank (103), and the feed inlet of the polymerization kettle (5) is connected with the discharge outlets of the fresh vinyl chloride storage tank (3) and the recovered vinyl chloride storage tank (4); The polymerization kettle (5) is provided with a stirring device; The polymerization kettle (5) is provided with a cooling water pipeline outside, and circulating cooling water flows through the cooling water pipeline.

5. The system of claim 1, wherein, The recovery separator (13) is provided with a feed inlet and a discharge outlet, and the feed inlet of the recovery separator (13) is connected with the gas phase outlets of the polymerization kettle (5), the discharge tank (7) and the stripping tower storage tank (8).

6. The system of claim 1, wherein, The secondary condenser (16) is provided with an inlet, an outlet and a gas phase outlet, the inlet of the secondary condenser (16) is connected with the gas phase outlet of the primary condenser (15), the outlet of the secondary condenser (16) is connected with the inlet of the recovered vinyl chloride storage tank (4), and the gas phase outlet of the secondary condenser (16) is connected with an exhaust treatment device.

7. The system of claim 1, wherein, The water storage tank (22) is provided with a water inlet and a water outlet, the water inlet of the water storage tank (22) is connected with the water outlet of the condensing separator (21), and the water inlet of the water storage tank (22) is also connected with the wastewater outlet of the centrifugal machine (17) and the water outlet of the polymerization kettle (5). The water storage tank (22) is also filled with flushing wastewater and ground wastewater during system operation.

8. The system of claim 1, wherein, The wastewater heat exchanger (23) is provided with a cold material inlet, a cold material outlet, a hot material inlet and a hot material outlet, and the cold material inlet of the wastewater heat exchanger (23) is connected with the water outlet of the water storage tank (22).

9. The system of claim 1, wherein, The wastewater stripping tower condenser (25) is provided with an inlet and an outlet, the inlet of the wastewater stripping tower condenser (25) is connected with the gas phase outlet of the wastewater stripping tower (24), and the outlet of the wastewater stripping tower condenser (25) is connected with the inlet of the recovered separator (13).

10. The system of claim 1, wherein, The pretreatment reactor (26) is provided with a water inlet and a water outlet, the water inlet of the pretreatment reactor (26) is connected with the hot material outlet of the wastewater heat exchanger (23), and the water outlet of the pretreatment reactor (26) is connected with a wastewater treatment device.

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