An apparatus and method for slowing down the self-polymerization of vinyl chloride monomer

Abstract

The present invention provides a device and method for slowing down the self-polymerization of vinyl chloride monomer, which relates to the technical field of chlor-alkali industrial production, and includes a spherical tank, a heat exchanger and a waste water tank; the heat exchanger includes an upper head, a body and a lower head, and the body includes a shell and a number of heat exchange tubes arranged inside; the spherical tank is provided with a first monomer reflux outlet, a waste water discharge outlet and a first monomer reflux inlet. The first monomer reflux outlet is led into the shell through a first reflux pipeline, and the first monomer reflux inlet is communicated with the shell through a second reflux pipeline; a monomer transfer pump is arranged on the first reflux pipeline; the waste water discharge outlet is led into the heat exchange tubes through a first waste water pipeline, and the heat exchange tubes are connected with the waste water tank through a second waste water pipeline; the present invention uses the heat exchanger to exchange heat between the cooled waste water after gas-liquid separation passing through the tube side and the vinyl chloride monomer passing through the shell side, and realizes the temperature reduction of the reflux circulating vinyl chloride monomer through heat energy exchange.

Description

Technical Field

[0001] The invention relates to the technical field of chlor-alkali industrial production, and in particular to a device and method for slowing down the self-polymerization of vinyl chloride monomer. Background Art

[0002] In the PVC production process, the self-polymerization of vinyl chloride monomer (VCM) is not only the primary problem restricting the normal operation of the distillation system, but also often causes the self-polymerization of the VCM tank and the monomer pipeline under the conditions of high temperature, high tank pressure or poor water removal, which has a great impact on the normal production of the polymerization system and the quality of PVC resin products. Therefore, by slowing down and eliminating the self-polymerization of VCM, production efficiency can be improved, production costs can be reduced and product quality can be improved.

[0003] In order to slow down or prevent the self-polymerization of vinyl chloride monomer, methods such as reducing the water content and oxygen content in the vinyl chloride monomer, controlling the pH value, adding inhibitors, controlling the liquid level and temperature of the vinyl chloride monomer storage tank, and controlling the pressure of the vinyl chloride monomer pipeline are generally used. The existing technology only controls the water content of the vinyl chloride monomer by draining water from the bottom of the vinyl chloride spherical tank to the wastewater tank to slow down the self-polymerization of the vinyl chloride monomer. This method is a commonly used method for controlling the water content of the vinyl chloride monomer and is also a method for slowing down the self-polymerization of the vinyl chloride monomer.

[0004] The Chinese patent application number CN202022434442.0 discloses a device for reducing the self-polymerization of vinyl chloride monomer in a spherical tank, including a refined monomer cooler, a spherical tank and a drainage tank. The inlet of the bottom pipe side of the refined monomer cooler is fixedly connected with a refined monomer pipeline, the outlet of the top pipe side of the refined monomer cooler and the inlet of the bottom of the spherical tank are fixedly connected with a refined monomer inlet pipeline, the drainage outlet at the bottom of the spherical tank and the water inlet at the top of the drainage tank are fixedly connected with a drainage pipeline, the water outlet at the bottom of the drainage tank is fixedly connected with a sewage pipeline, and the air inlet in the middle of the drainage tank is fixedly connected with a low-pressure steam pipeline. The utility model reduces the temperature and pressure of the spherical tank by cooling the vinyl chloride monomer entering the spherical tank and automatically draining the spherical tank, and the spherical tank has a significant dehydration effect when standing, reducing the self-polymerization phenomenon. The wastewater discharged from the spherical tank contains about 50% vinyl chloride monomer. Vinyl chloride is a colorless, easily liquefied gas with a boiling point of -13.9°C, so it is easy to vaporize from the wastewater, and vaporization will take away a lot of heat. The reduction in temperature can also slow down the self-polymerization of vinyl chloride monomer. However, there is no direct connection between the drainage tank and the cooler of the above device, resulting in heat waste.

[0005] The invention patent application No. CN202020855873.1 discloses a distillation device for photocurable monomers, including a distillation column with a feed pipe connected to the top. A top spray head, a middle spray head and a reflux pipe are arranged successively from top to bottom. The gaseous monomers enter the distillation column through the feed pipe, are condensed into liquid phase by a condenser and enter a reflux tank. Part of it is transported to a finished product tank and part is refluxed to the top of the distillation column to achieve the reflux ratio of the distillation process. After being mixed with a quantitatively transported anaerobic inhibitor, it is sprayed through the top spray head to reduce the self-polymerization risk of the gaseous monomers in the upper part of the distillation column. At the same time, the liquid monomers containing a high concentration of inhibitor accumulate at the bottom of the distillation column and are transported to the middle spray head through the reflux pipe and sprayed to reduce the self-polymerization risk of the gaseous monomers in the middle and lower parts of the distillation column. However, this device does not consider the discharge of wastewater.

[0006] Therefore, it is necessary to provide a device and method that can reasonably utilize the discharged wastewater to reduce the temperature of the vinyl chloride monomers in the reflux cycle and slow down the self-polymerization of the vinyl chloride monomers in the spherical tank. Summary of the Invention

[0007] Based on the above problems, the purpose of the present invention is to provide a device and method for slowing down the self-polymerization of vinyl chloride monomers.

[0008] To achieve the above purpose, the present invention provides the following technical solutions:

[0009] A device for slowing down the self-polymerization of vinyl chloride monomers, including a spherical tank, a heat exchanger and a wastewater tank;

[0010] The heat exchanger includes a upper head, a body and a lower head that are hermetically connected to each other. The body includes a shell and a number of heat exchange tubes arranged inside; there is a certain gap between the shell and the heat exchange tubes;

[0011] The spherical tank is provided with a first monomer reflux outlet, a wastewater discharge outlet and a first monomer reflux inlet,

[0012] The first monomer reflux outlet leads into the shell through a first reflux pipe, and the first monomer reflux inlet is communicated with the shell through a second reflux pipe; a monomer transfer pump is provided on the first reflux pipe; the vinyl chloride monomers pumped out from the spherical tank enter the shell through the first reflux pipe, then flow through the inside of the body and return to the spherical tank through the second reflux pipe;

[0013] The wastewater discharge outlet leads into the heat exchange tubes through a first wastewater pipe, and the heat exchange tubes are connected to the wastewater tank through a second wastewater pipe; the wastewater discharged from the spherical tank enters the heat exchange tubes through the first wastewater pipe, the wastewater flows through the heat exchange tubes and then flows into the wastewater tank through the second wastewater pipe;

[0014] The top of the heat exchanger is provided with a first exhaust port, and the first exhaust port leads to a gas holder through a first exhaust pipeline. The vinyl chloride monomer vaporized during the process of wastewater flowing through the heat exchange tubes is led to the gas holder through the first exhaust pipeline for recovery.

[0015] Preferably, a second monomer reflux outlet and a second monomer reflux inlet are respectively provided above and below the shell, and the first monomer reflux outlet and the second monomer reflux inlet are connected through the first reflux pipeline; the second monomer reflux outlet and the first monomer reflux inlet are connected through the second reflux pipeline. There is a certain gap between the shell and the heat exchange tubes, and the vinyl chloride monomer pumped out from the spherical tank flows through the shell side inside the heat exchanger and then returns to the spherical tank.

[0016] Preferably, a wastewater inlet is provided on the upper head, and the wastewater discharge port is connected to the wastewater inlet through a first wastewater pipeline; a wastewater outlet is provided at the bottom of the lower head, and the wastewater outlet is connected to the wastewater tank through the second wastewater pipeline. The vinyl chloride monomer discharged from the spherical tank flows through the tube side inside the heat exchanger and then flows into the wastewater tank.

[0017] Preferably, a first reflux valve and a second reflux valve are sequentially arranged between the first reflux outlet and the monomer delivery pump, a third reflux valve and a fourth reflux valve are sequentially arranged between the monomer delivery pump and the second monomer reflux inlet, and a fifth reflux valve is arranged on the second reflux pipeline. The first reflux valve controls the flow rate and velocity of the liquid discharged from the spherical tank, and the second reflux valve is close to the monomer delivery valve. The third reflux valve and the fourth reflux valve control the flow rate and velocity of the vinyl chloride monomer pumped into the heat exchanger.

[0018] Preferably, a branch pipeline is further arranged on the first reflux pipeline, and the branch pipeline leads to a polymerization kettle. The vinyl chloride monomer pumped out from the spherical tank is divided into two parts in the first reflux pipeline. Most of them enter the polymerization kettle through the branch pipeline for polymerization reaction, and a small part flows into the heat exchanger to exchange heat with the wastewater in the heat exchanger and then returns to the spherical tank, which can slow down the occurrence of self-polymerization.

[0019] Preferably, the branch pipeline is arranged between the third reflux valve and the fourth reflux valve. The third reflux valve is before the branch pipeline and can control the diversion of the vinyl chloride monomer pumped out between the branch pipeline and the second reflux pipeline, and the fourth reflux valve controls the flow rate and velocity of the diverted vinyl chloride monomer entering the heat exchanger.

[0020] Preferably, a first drain valve and an automatic regulating valve are arranged on the first wastewater pipeline, and a second drain valve is arranged on the second wastewater pipeline. The automatic regulating valve can control the flow rate and velocity of the wastewater discharge and control the heat exchange degree.

[0021] Preferably, the wastewater tank leads to the polymerization wastewater stripping tower through the third wastewater pipeline, and a third drain valve is provided on the third wastewater pipeline. The wastewater in the wastewater tank finally enters the polymerization wastewater stripping tower for distillation to improve the wastewater recovery rate and utilization rate.

[0022] Preferably, a second exhaust port is provided at the top of the wastewater tank, and the second exhaust port is connected to the first exhaust pipeline through a second exhaust pipeline. There will also be a situation where vinyl chloride monomer vaporizes in the wastewater collected in the wastewater tank. The vaporized vinyl chloride monomer flows back through the second exhaust pipeline and the first exhaust pipeline and is jointly transported to the gas holder for recovery.

[0023] Preferably, a first exhaust valve and a second exhaust valve are respectively provided on the first exhaust pipeline and the second exhaust pipeline. The first exhaust valve and the second exhaust valve control the flow rate and velocity of the vaporized vinyl chloride monomer in the first exhaust pipeline and the second exhaust pipeline entering the gas holder.

[0024] A method for slowing down the self-polymerization of vinyl chloride monomer is also provided, including the following steps:

[0025] Step 1: The wastewater in the spherical tank is introduced into the heat exchange tubes of the heat exchanger through the first wastewater pipeline, flows through the heat exchange tubes, and the residual vinyl chloride monomer in the wastewater vaporizes, cooling the wastewater and the heat exchange tubes, and then flows into the wastewater tank through the second wastewater pipeline;

[0026] Step 2: The vinyl chloride monomer in the spherical tank is introduced into the body of the heat exchanger through a monomer transfer pump. The vinyl chloride monomer flows through the gap between the shell of the body and the heat exchange tubes, exchanges heat with the wastewater in the heat exchange tubes, and reduces the temperature of the vinyl chloride monomer;

[0027] Step 3: The cooled vinyl chloride monomer flows back to the spherical tank through the second reflux pipeline.

[0028] Preferably, in Step 1, when the wastewater flows through the heat exchange tubes, part of the vaporized residual vinyl chloride monomer is discharged into the gas holder, and the other part flows into the wastewater tank together with the wastewater.

[0029] Preferably, the vaporized residual vinyl chloride monomer in the wastewater tank is discharged into the gas holder, and the wastewater flows into the polymerization wastewater stripping tower.

[0030] Preferably, in Step 2, after the vinyl chloride monomer is introduced by the monomer transfer pump, it is divided into reflux vinyl chloride monomer and reaction vinyl chloride monomer. The reflux vinyl chloride monomer enters the body of the heat exchanger, and the reaction vinyl chloride monomer is introduced into the polymerization kettle.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] The device for preventing the self - polymerization of vinyl chloride monomer provided by the present invention mainly includes two parts: a reflux system and a waste discharge system. The vinyl chloride monomer pumped out from the spherical tank is introduced into the shell through the first reflux pipeline, then flows through the interior of the main body and returns to the spherical tank through the second reflux pipeline. At the same time, the wastewater discharged from the spherical tank is introduced into the heat exchange tube through the first wastewater pipeline. The wastewater flows through the heat exchange tube and then flows into the wastewater tank through the second wastewater pipeline. Or first, the waste discharge system is started to discharge the wastewater, and then the reflux system is started.

[0033] When the wastewater flows through the heat exchange tube, that is, through the tube side of the heat exchanger, the vinyl chloride monomer contained in the wastewater vaporizes, taking away a large amount of heat, which rapidly reduces the temperature of the wastewater in the heat exchange tube. When the vinyl chloride monomer fluid pumped out from the spherical tank passes through the shell side of the heat exchanger (i.e., the gap between the shell of the heat exchanger main body and the heat exchange tube), the vinyl chloride monomer contacts the heat exchange tube and exchanges heat with the low - temperature wastewater in the heat exchange tube, reducing the temperature of the vinyl chloride monomer in the shell side. Finally, it returns to the spherical tank through the second reflux pipeline, and the cooling of the reflux - circulating vinyl chloride monomer is achieved by heat energy exchange. By reflux, the circulating fluidity of the vinyl chloride monomer in the spherical tank is increased. At the same time, the heat - exchanged vinyl chloride monomer enters the spherical tank to reduce the temperature, further slowing down the self - polymerization of the vinyl chloride monomer. Therefore, the device and method provided by the present invention achieve the effect of slowing down the self - polymerization of vinyl chloride monomer in three aspects: draining water from the bottom of the spherical tank to the wastewater tank to control the water content of the vinyl chloride monomer in the spherical tank; increasing the circulating fluidity of the vinyl chloride monomer in the spherical tank; refluxing part of the vinyl chloride monomer to exchange heat with the wastewater to reduce the ambient temperature in the spherical tank. While slowing down the self - polymerization of vinyl chloride monomer, it can also effectively recycle the wastewater and maximize the heat effect of the wastewater. Brief Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of a device for slowing down the self - polymerization of vinyl chloride monomer according to the present invention;

[0035] Reference Signs:

[0036] 1 - spherical tank, 2 - heat exchanger, 201 - main body, 202 - lower head, 203 - upper head, 3 - wastewater tank,

[0037] 4 - first reflux pipeline, 5 - second reflux pipeline, 6 - first wastewater pipeline, 7 - second wastewater pipeline,

[0038] 8 - first exhaust pipeline, 9 - branch pipeline, 10 - polymerization wastewater stripping tower, 11 - gas holder, 12 - polymerization kettle,

[0039] 13 - monomer transfer pump, 14 - first reflux valve, 15 - second reflux valve, 16 - third reflux valve,

[0040] 17 - Fourth reflux valve, 18 - Fifth reflux valve, 19 - Second exhaust pipe, 20 - First drain valve,

[0041] 21 - Automatic regulating valve, 22 - Second drain valve, 23 - Third drain valve, 24 - First exhaust valve,

[0042] 25 - Second exhaust valve. Detailed implementation mode

[0043] To make the objectives and technical solutions of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention in combination with the embodiments of the present invention.

[0044] In the description of this application, it should be understood that the orientation or positional relationships indicated by the terms "length", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this application.

[0045] As Figure 1 shown, the present invention provides a device for slowing down the self - polymerization of vinyl chloride monomer,

[0046] including a spherical tank 1, a heat exchanger 2 and a waste water tank 3; the spherical tank 1 is a large - capacity, pressure - bearing spherical storage container, and a large amount of liquid containing vinyl chloride monomer is stored in the spherical tank 1.

[0047] The heat exchanger 2 includes a upper head 203, a body 201 and a lower head 202 which are hermetically connected to each other. The connections between the upper head 203 and the body 201 and between the lower head 202 and the body 201 are both sealed to ensure that the fluid will not leak. The body 201 includes a shell and a number of heat exchange tubes arranged inside; the heat exchange tubes are generally arranged evenly, there is a certain gap between adjacent two heat exchange tubes, or the outer walls of all the heat exchange tubes are tangent to each other and closely connected together; there is a certain gap between the shell and the heat exchange tubes for the fluid to flow through.

[0048] The bottom of the spherical tank 1 is provided with a first monomer reflux outlet, a waste water discharge outlet and a first monomer reflux inlet, where the waste water discharge outlet is located directly below the spherical tank 1, and the first monomer reflux outlet and the first monomer reflux inlet are respectively arranged on both sides or the same side of the waste water discharge outlet.

[0049] Above and below the said housing are respectively provided with a second monomer reflux outlet and a second monomer reflux inlet, the second monomer reflux outlet and the second monomer reflux inlet lead to the interior of the housing of the heat exchanger 2, and the first monomer reflux outlet is connected to the second monomer reflux inlet through a first reflux pipeline 4; the second monomer reflux outlet is connected to the first monomer reflux inlet through a second reflux pipeline. There is a certain gap between the housing and the heat exchange tubes, and a monomer transfer pump 13 is provided on the first reflux pipeline 4; the monomer transfer pump 13 can transfer vinyl chloride monomer in the spherical tank 1, and the concentration of vinyl chloride monomer at the outlet of the monomer transfer pump 13 is extremely high, which can reach more than 99.99%. A first reflux valve 14 and a second reflux valve 15 are successively provided between the first reflux outlet and the monomer transfer pump 13, a third reflux valve 16 and a fourth reflux valve 17 are successively provided between the monomer transfer pump 13 and the second monomer reflux inlet, and a fifth reflux valve 18 is provided on the second reflux pipeline 5. The first reflux valve 14 controls the flow rate and velocity of the liquid discharged from the spherical tank 1, and the second reflux valve 15 is close to the monomer transfer valve; the third reflux valve 16 and the fourth reflux valve 17 control the flow rate and velocity of the pumped vinyl chloride monomer entering the heat exchanger 2; the fifth reflux valve 18 can control the flow rate and velocity of the vinyl chloride monomer after heat exchange inside the heat exchanger 2 entering the spherical tank 1. The vinyl chloride monomer pumped out from the spherical tank 1 is introduced into the housing through the first reflux pipeline 4, and then flows through the interior of the body 201. Specifically, after flowing through the shell side inside the heat exchanger 2 (i.e., the gap between the housing and the heat exchange tubes), it then returns to the spherical tank 1 through the second reflux pipeline 5. With the help of the monomer transfer pump 13, partial monomer circulation is completed without adding a new piece of equipment.

[0050] A waste water inlet is provided on the said upper head 203, and the waste water discharge outlet is connected to the waste water inlet through a first waste water pipeline 6; a waste water outlet is provided at the bottom of the lower head 202, and the waste water outlet is connected to the waste water tank 3 through the second waste water pipeline 7. A first drain valve 20 and an automatic regulating valve 21 are provided on the first waste water pipeline 6, and a second drain valve 22 is provided on the second waste water pipeline 7. The automatic regulating valve 21 can control the flow rate and velocity of the discharged waste water, and the second drain valve 22 controls the flow rate and velocity of the waste water entering the waste water tank 3 from the heat exchanger 2. The vinyl chloride monomer discharged from the spherical tank 1 flows through the tube side inside the heat exchanger 2 and then flows into the waste water tank 3; the waste water discharged from the spherical tank 1 is introduced into the heat exchange tubes through the first waste water pipeline 6, and the waste water flows through the heat exchange tubes and then flows into the waste water tank 3 through the second waste water pipeline 7.

[0051] The flow pattern of the above wastewater in the heat exchanger 2 is from top to bottom; in addition, the wastewater inlet and the wastewater outlet can also be respectively arranged on the lower head 202 and the upper head 203, and the actual direction of the wastewater flowing through the heat exchange tubes can also be from bottom to top. Therefore, the direction of the wastewater flowing through the heat exchange tubes can be selected from two modes: from top to bottom or from bottom to top according to the positions of the wastewater inlet and the wastewater outlet.

[0052] When the wastewater flows through the heat exchange tubes, that is, through the tube side of the heat exchanger 2 (i.e., flows through the heat exchange tubes), the vinyl chloride monomer contained in the wastewater vaporizes, taking away a large amount of heat, and rapidly reducing the temperature of the wastewater in the heat exchange tubes. When the vinyl chloride monomer fluid pumped out from the spherical tank 1 passes through the shell side of the heat exchanger 2 (i.e., flows through the gap between the shell of the main body 201 of the heat exchanger 2 and the heat exchange tubes), the vinyl chloride monomer contacts the heat exchange tubes and exchanges heat with the low-temperature wastewater in the heat exchange tubes, reducing the temperature of the vinyl chloride monomer in the shell side, and finally returning to the spherical tank 1 through the second return pipeline 5, realizing the cooling of the recycled vinyl chloride monomer by heat energy exchange. By recycling, the circulating fluidity of the vinyl chloride monomer in the spherical tank 1 is increased, and at the same time, the vinyl chloride monomer after heat exchange enters the spherical tank 1 to reduce the internal environmental temperature of the spherical tank 1, further slowing down the self-polymerization of the vinyl chloride monomer.

[0053] A first exhaust port is provided at the top of the heat exchanger 2, and the first exhaust port leads to the gas holder 11 through a first exhaust pipeline 8. A first exhaust valve 24 is provided on the first exhaust pipeline 8, and the vinyl chloride monomer vaporized during the process of the wastewater flowing through the heat exchange tubes can be led to the gas holder 11 through the first exhaust pipeline 8 for recovery. A second exhaust port is provided at the top of the wastewater tank 3, and the second exhaust port is communicated with the first exhaust pipeline 8 through a second exhaust pipeline 19. A second exhaust valve 25 is provided on the second exhaust pipeline 19. There will also be a situation where the vinyl chloride monomer vaporizes in the wastewater collected in the wastewater tank 3. The vaporized vinyl chloride monomer flows back through the second exhaust pipeline 19 and the first exhaust pipeline 8 and is jointly transported to the gas holder 11 for recovery. The first exhaust valve 24 and the second exhaust valve 25 control the flow rate and velocity of the vaporized vinyl chloride monomer entering the gas holder 11 in the first exhaust pipeline 8 and the second exhaust pipeline 19.

[0054] The wastewater tank 3 leads to the polymer wastewater stripping tower 10 through a third wastewater pipeline, and a third drain valve 23 is provided on the third wastewater pipeline. The wastewater in the wastewater tank 3 finally enters the polymer wastewater stripping tower 10 for stripping to improve the wastewater recovery rate and utilization rate. While slowing down the self-polymerization of the vinyl chloride monomer, the wastewater can also be effectively recycled, maximizing the heat effect of the wastewater.

[0055] A branch pipeline 9 is also provided on the first reflux pipeline 4, and this branch pipeline leads to the subsequent main reaction stage, and the branch pipeline 9 leads to the polymerization kettle 12. The vinyl chloride monomer pumped out from the spherical tank 1 is divided into two parts in the first reflux pipeline 4. The vast majority of it enters the polymerization kettle 12 through the branch pipeline 9 for polymerization reaction, and a small part flows into the heat exchanger 2. Through the shell side of the heat exchanger 2, it exchanges heat with the cooled wastewater passing through the tube side, thereby reducing the temperature of the reflux vinyl chloride monomer. And it is refluxed to the spherical tank 1 again through the heat exchanger 2, causing the average temperature in the spherical tank 1 to drop, strengthening the circulating flow of the vinyl chloride monomer at the bottom of the spherical tank 1, thereby slowing down the self-polymerization of the vinyl chloride monomer, being beneficial to improving the quality of vinyl chloride products, delaying the blockage of equipment pipelines and reducing the system resistance, etc.

[0056] The branch pipeline 9 is arranged between the third reflux valve 16 and the fourth reflux valve 17. The third reflux valve 16 is before the branch pipeline 9 and can control the diversion of the pumped-out vinyl chloride monomer between the branch pipeline 9 and the second reflux pipeline 5. The fourth reflux valve 17 controls the flow rate and velocity of the diverted vinyl chloride monomer entering the heat exchanger 2. The third reflux valve 16 and the fourth reflux valve 17 can control the amount of the refluxed vinyl chloride monomer.

[0057] The present invention also provides a method for slowing down the self-polymerization of vinyl chloride monomer, including the following steps:

[0058] Step 1: The wastewater in the spherical tank 1 is introduced into the heat exchange tubes of the heat exchanger 2 through the first wastewater pipeline 6, flows through the heat exchange tubes, the residual vinyl chloride monomer in the wastewater vaporizes, cooling the wastewater and the heat exchange tubes, and then flows into the wastewater tank 3 through the second wastewater pipeline 7; when the wastewater flows through the heat exchange tubes, a part of the vaporized residual vinyl chloride monomer is discharged into the gas holder 11, and the other part flows into the wastewater tank 3 together with the wastewater. The vaporized residual vinyl chloride monomer in the wastewater tank 3 is discharged into the gas holder 11, and the wastewater flows into the polymer wastewater stripping tower 10.

[0059] Step 2: The vinyl chloride monomer in the spherical tank 1 is introduced into the body 201 of the heat exchanger 2 through the monomer delivery pump 13. After the vinyl chloride monomer is introduced through the monomer delivery pump 13, it is divided into two parts: reflux vinyl chloride monomer and reaction vinyl chloride monomer. The reflux vinyl chloride monomer enters the body 201 of the heat exchanger 2 and flows through the gap between the shell of the body 201 and the heat exchange tubes, exchanging heat with the wastewater in the heat exchange tubes to reduce the temperature of the vinyl chloride monomer; the reaction vinyl chloride monomer is introduced into the polymerization kettle 12.

[0060] Step 3: The cooled vinyl chloride monomer is refluxed to the spherical tank 1 through the second reflux pipeline 5.

[0061] The device for preventing the self-polymerization of vinyl chloride monomer provided by the present invention can be divided into two parts: a reflux system and a waste discharge system. The vinyl chloride monomer pumped out from the spherical tank 1 is introduced into the housing through the first reflux pipeline 4, then flows through the interior of the body 201 and returns to the spherical tank 1 through the second reflux pipeline 5. At the same time, the wastewater discharged from the spherical tank 1 is introduced into the heat exchange tube through the first wastewater pipeline 6. The wastewater flows through the heat exchange tube and then flows into the wastewater tank 3 through the second wastewater pipeline 7, or the waste discharge system is first started to discharge the wastewater, and then the reflux system is started. The slowing effect of the self-polymerization of vinyl chloride monomer is achieved in three aspects: draining the water at the bottom of the spherical tank 1 to the wastewater tank 3 to control the water content of the vinyl chloride monomer in the spherical tank 1; increasing the circulating flow of the vinyl chloride monomer in the spherical tank 1; and refluxing part of the vinyl chloride monomer to exchange heat with the wastewater to reduce the ambient temperature in the spherical tank 1.

[0062] The above is only a partial embodiment of the present invention, and its description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these obvious replacement forms all belong to the protection scope of the present invention.

Claims

1. An apparatus for slowing down the self - polymerization of vinyl chloride monomer, characterized in that: It includes a spherical tank, a heat exchanger and a waste water tank; the heat exchanger includes a top head, a body and a bottom head which are hermetically connected to each other, and the body includes a shell and a number of heat exchange tubes arranged inside; The spherical tank is provided with a first monomer reflux outlet, a waste water discharge outlet and a first monomer reflux inlet, The first monomer reflux outlet leads into the shell through a first reflux pipeline, and the first monomer reflux inlet is communicated with the shell through a second reflux pipeline; a monomer transfer pump is provided on the first reflux pipeline; the waste water discharge outlet leads into the heat exchange tubes through a first waste water pipeline, and the heat exchange tubes are connected to the waste water tank through a second waste water pipeline; A first exhaust port is provided at the top of the heat exchanger, and the first exhaust port leads to a gas holder through a first exhaust pipeline; a second monomer reflux outlet and a second monomer reflux inlet are respectively provided above and below the shell, and the first monomer reflux outlet is connected to the second monomer reflux inlet through the first reflux pipeline; the second monomer reflux outlet is connected to the first monomer reflux inlet through the second reflux pipeline; A waste water inlet is provided on the top head, and the waste water discharge outlet is connected to the waste water inlet through a first waste water pipeline; a waste water outlet is provided at the bottom of the bottom head, and the waste water outlet is connected to the waste water tank through the second waste water pipeline; a first reflux valve and a second reflux valve are successively provided between the first monomer reflux outlet and the monomer transfer pump, a third reflux valve and a fourth reflux valve are successively provided between the monomer transfer pump and the second monomer reflux inlet, and a fifth reflux valve is provided on the second reflux pipeline.

2. A device for slowing down the self-polymerization of vinyl chloride monomer according to claim 1, characterized in that: A branch pipeline is further provided on the first reflux pipeline, and the branch pipeline leads to a polymerization kettle; the branch pipeline is arranged between the third reflux valve and the fourth reflux valve.

3. A device for slowing down the self-polymerization of vinyl chloride monomer according to claim 1, characterized in that: A first drain valve and an automatic regulating valve are provided on the first waste water pipeline, and a second drain valve is provided on the second waste water pipeline.

4. A device for slowing down the self-polymerization of vinyl chloride monomer according to claim 1, characterized in that: The waste water tank leads to a polymerization waste water stripping tower through a third waste water pipeline, and a third drain valve is provided on the third waste water pipeline; A second exhaust port is provided at the top of the waste water tank, and the second exhaust port is connected to the first exhaust pipeline through a second exhaust pipeline.

5. The device for slowing down the self-polymerization of vinyl chloride monomer according to claim 4, characterized in that: A first exhaust valve and a second exhaust valve are respectively provided on the first exhaust pipeline and the second exhaust pipeline.

6. A method for slowing down the self-polymerization of vinyl chloride monomer, characterized in that: It includes the following steps: Step 1: The waste water in the spherical tank is led into the heat exchange tubes of the heat exchanger through a first waste water pipeline, flows through the heat exchange tubes, the residual vinyl chloride monomer in the waste water vaporizes, cools the waste water and the heat exchange tubes, and then flows into the waste water tank through a second waste water pipeline; Step 2: The vinyl chloride monomer in the spherical tank is introduced into the main body of the heat exchanger through a monomer transfer pump. Part of the vinyl chloride monomer flows through the gap between the housing of the main body and the heat exchange tubes, exchanges heat with the wastewater in the heat exchange tubes, and reduces the temperature of the vinyl chloride monomer. Step 3: The cooled vinyl chloride monomer flows back to the spherical tank through a second reflux pipeline.

7. A method for slowing down the self-polymerization of vinyl chloride monomer according to claim 6, wherein: In Step 1, when the wastewater flows through the heat exchange tubes, part of the residual vinyl chloride monomer after vaporization is discharged into the gas holder, and the other part flows into the wastewater tank together with the wastewater.

8. A method for slowing down the self-polymerization of vinyl chloride monomer according to claim 6, characterized in that: In Step 2, after the vinyl chloride monomer is introduced by the monomer transfer pump, it is divided into reflux vinyl chloride monomer and reaction vinyl chloride monomer. The reflux vinyl chloride monomer enters the main body of the heat exchanger, and the reaction vinyl chloride monomer is introduced into the polymerization kettle.

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