Reaction terminating system for rapidly injecting polymerization inhibitor into PVDF (Polyvinylidene Fluoride) polymerization kettle

Abstract

The utility model discloses a reaction termination system for quickly injecting a polymerization inhibitor into a PVDF (Polyvinylidene Fluoride) polymerization kettle, and belongs to the technical field of polyvinylidene fluoride. According to the technical scheme, the system comprises a controller, an emulsion polymerization kettle and a polymerization inhibitor tank, the emulsion polymerization kettle and the polymerization inhibitor tank are connected through a pipeline, the emulsion polymerization kettle is connected with a balance tank through a pipeline, and the emulsion polymerization kettle is further provided with a VDF feeding pipeline, an auxiliary feeding pipeline and a pure water feeding pipeline; the VDF feeding pipeline is provided with a flow sensor II, a regulating valve, a stop valve I, a switch control valve II and a pressure sensor I; a switch control valve III and a flow sensor II are arranged on the assistant feeding pipeline; the emulsion polymerization kettle is further provided with a PVDF resin outlet pipeline and an emptying pipeline, and a fourth switch control valve is arranged on the PVDF resin outlet pipeline. According to the utility model, the problem of major safety accidents such as fire and explosion caused by overtemperature and overpressure of the polymerization kettle due to continuous polymerization under the abnormal reaction working condition of the polymerization kettle can be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of polyvinylidene fluoride, and in particular relates to a system for rapidly injecting a polymerization inhibitor into a PVDF polymerization kettle to terminate the reaction. Background Art

[0002] The production process of hazardous chemical processes often involves flammable, explosive and toxic hazardous substances. The leakage of these hazardous substances can easily lead to serious environmental disasters and emergencies. At the same time, hazardous chemical production equipment is a complex system, and its production is mainly carried out under unfavorable conditions such as high temperature and high pressure, which can lead to serious safety problems such as explosions and toxic gas leaks. Therefore, strengthening the chemical industry is crucial to the safe management of the production of hazardous chemicals.

[0003] Polyvinylidene fluoride (PVDF) is a polymer formed by the polymerization of the monomer vinylidene fluoride (VDF). According to the polymerization reaction mechanism: VDF polymerization can be divided into bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization and other polymerization methods. In industrial production, suspension polymerization and emulsion polymerization are the main methods. The emulsion polymerization of VDF is actually a precipitation polymerization of a dilute aqueous solution. Its process includes: ① the mass transfer process of VDF monomer dissolving in the aqueous phase ② dilute aqueous solution polymerization; ③ the polymer product particles are insoluble in water and precipitate from the aqueous phase, and form a dispersion under the action of a dispersant. The emulsion polymerization method is used to prepare PVDF resin. In the polymerization system where emulsifiers, initiators, chain transfer agents, stabilizers, etc. are present, a certain polymerization pressure and polymerization temperature are maintained, and VDF monomers are continuously introduced for polymerization reaction. Emulsion polymerization can be carried out under certain polymerization temperature and faster polymerization speed conditions. The polymerization reaction rate is controlled steadily, the primary particle size is small, and the product quality is good. Chinese utility model patent CN217164365U discloses a reaction device for preparing PVDF, which includes a reaction tank, a feed pipe, a discharge port, a drive motor, a coupling, a stirring shaft and a stirring paddle; the feed pipe and the discharge port are connected on the reaction tank; the drive motor is fixedly arranged on the top of the reaction tank and is fixedly connected to the stirring shaft through a coupling; the stirring paddle is fixedly connected to the stirring shaft, the outlet of the feed pipe is arranged below the liquid surface of the reaction medium, and an interlayer is provided in the reaction tank to control the temperature in the reaction tank, which solves the problem that the temperature in the reaction process is easy to exceed the critical temperature of the VDF monomer and turn VDF into gas, can monitor and adjust the reaction temperature in real time, and improve the product quality and yield. However, in the polymerization process, there may be an excessive amount of initiator or an excessively high initiator concentration, which accelerates the reaction speed, increases the reaction temperature and reaction pressure very quickly, and thus produces a large amount of implosion, resulting in the implosion blocking the reactor venting device and the bursting disc port of the polymerization reactor out of control, thereby causing the product quality to be unqualified and causing major safety accidents. Utility Model Content

[0004] The utility model provides a system for rapidly injecting an inhibitor into a PVDF polymerization kettle to terminate the reaction, which can reduce the problem of major safety accidents such as fire and explosion caused by continued polymerization under abnormal reaction conditions of the polymerization kettle, thereby causing over-temperature and over-pressure of the polymerization kettle.

[0005] The technical solution of the utility model is:

[0006] A system for rapidly injecting an inhibitor into a PVDF polymerization kettle to terminate the reaction comprises a controller and an emulsion polymerization kettle and an inhibitor tank connected by pipelines, wherein the emulsion polymerization kettle is connected to a balancing tank by pipelines, and the emulsion polymerization kettle is also provided with a VDF feeding pipeline, an auxiliary agent feeding pipeline and a pure water feeding pipeline; the pure water feeding pipeline is provided with a flow sensor 1 and a switch control valve 1, and the flow sensor 1 and the switch control valve 1 are both electrically connected to the controller; the VDF feeding pipeline is provided with a flow sensor 2, a regulating valve, a cut-off valve 1, a switch control valve 2 and a pressure sensor 1, and the flow sensor 2, a regulating valve, a cut-off valve 1, a switch control valve 2 and a pressure sensor 1 are provided Sensor 1 is electrically connected to the controller; a switch control valve 3 and a flow sensor 2 are provided on the additive feed pipeline, and the switch control valve 3 and the flow sensor 2 are electrically connected to the controller; the emulsion polymerization kettle is also provided with a PVDF resin outlet pipeline and a vent pipeline, and a switch control valve 4 is provided on the PVDF resin outlet pipeline; the inhibitor tank is connected to a pressure sensor 2, and the pressure sensor 2 is electrically connected to the controller. The inhibitor tank is also connected to a high-pressure nitrogen cylinder through a nitrogen input pipeline, and the pressure is 13MPa. A high-pressure nitrogen cylinder gas source valve is provided on the nitrogen input pipeline, and the high-pressure nitrogen cylinder gas source valve is electrically connected to the controller.

[0007] Preferably, a pure water filter is provided on the pure water feed pipeline.

[0008] Preferably, a vent cut-off valve is provided on the vent pipeline.

[0009] Preferably, a polymerization inhibitor discharge valve is provided on the pipeline between the emulsion polymerization kettle and the polymerization inhibitor tank, and the polymerization inhibitor discharge valve is electrically connected to the controller.

[0010] Preferably, one end of the additive feeding pipeline away from the emulsion polymerization kettle is connected to the additive barrel, and an additive pump is arranged on the additive feeding pipeline.

[0011] Preferably, a pressure sensor three is also provided on the additive feed pipeline, and the pressure sensor three is electrically connected to the controller.

[0012] Compared with the prior art, the utility model has the following beneficial effects:

[0013] 1. The utility model can reduce the problem that polymerization continues to occur under abnormal reaction conditions of the polymerization kettle, thereby causing over-temperature and over-pressure of the polymerization kettle, resulting in major safety accidents such as fire and explosion.

[0014] 2. The conventional system method of injecting inhibitors by pumps has been eliminated, and the machine can no longer be used due to unexpected situations caused by mechanical problems;

[0015] 3. The inlet of the inhibitor tank is connected to a 13MPa high-pressure nitrogen cylinder to respond to emergencies at any time and reduce the safety accident rate;

[0016] 4. The inhibitor discharge valve is connected to the SIS system. When the pressure or temperature of the emulsion polymerization kettle is too high, the interlock closes the shut-off valve 1 (VDF feed shut-off valve), the interlock opens the vent shut-off valve, the interlock automatically opens the 13MPa high-pressure nitrogen cylinder gas source valve, and the inhibitor discharge valve is automatically opened to quickly add the inhibitor to prevent the reaction. Compared with the conventional system connected to the inhibitor pump, the required pump flow is too small and the pressure is high, the response time is long, and the power supply used is a first-level load that needs to be kept in a normally open state, which increases equipment investment and power consumption. The high-pressure nitrogen cylinder can quickly add inhibitors, which is safe and fast, reduces equipment investment and power consumption, and shortens the response time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the utility model.

[0018] In the figure, 1, emulsion polymerization kettle; 2, inhibitor tank; 201, pressure sensor 2; 3, balance tank; 4, VDF feed pipeline; 401, flow sensor 2; 402, regulating valve; 403, cut-off valve 1; 404, switch control valve 2; 405, pressure sensor 1; 5, additive feed pipeline; 501, switch control valve 3; 502, flow sensor 2; 503, additive barrel; 504, additive pump; 505, pressure sensor 3; 6, pure water feed pipeline; 601, flow sensor 1; 602, switch control valve 1; 603, pure water filter; 7, PVDF resin outlet pipeline; 701, switch control valve 4; 8, vent pipeline; 801, vent cut-off valve; 10, nitrogen input pipeline; 11, high-pressure nitrogen cylinder; 1101, high-pressure nitrogen cylinder gas source valve; 12, inhibitor discharge valve. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0020] Example 1

[0021] like Figure 1 As shown, a system for rapidly injecting an inhibitor into a PVDF polymerization kettle to terminate the reaction comprises a controller and an emulsion polymerization kettle 1 and an inhibitor tank 2 connected by pipelines, the emulsion polymerization kettle is connected to a balance tank 3 by pipelines, the emulsion polymerization kettle 1 is also provided with a VDF feed pipeline 4, an auxiliary agent feed pipeline 5 and a pure water feed pipeline 6; an inhibitor discharge valve 12 is provided on the pipeline between the emulsion polymerization kettle 1 and the inhibitor tank 2, and the inhibitor discharge valve 12 is electrically connected to the controller;

[0022] The pure water feed pipeline 6 is provided with a flow sensor 601 and a switch control valve 602, both of which are electrically connected to the controller, and a pure water filter 603 is provided on the pure water feed pipeline 6;

[0023] The VDF feed pipeline 4 is provided with a flow sensor 2 401, a regulating valve 402, a cut-off valve 1 403, a switch control valve 2 404 and a pressure sensor 1 405, and the flow sensor 2 401, the regulating valve 402, the cut-off valve 1 403, the switch control valve 2 404 and the pressure sensor 1 405 are all electrically connected to the controller;

[0024] The additive feed pipeline 5 is provided with a switch control valve 3 501 and a flow sensor 2 502, and the switch control valve 3 501 and the flow sensor 2 502 are both electrically connected to the controller. The end of the additive feed pipeline 5 away from the emulsion polymerization kettle 1 is connected to the additive barrel 503, and the additive feed pipeline 5 is provided with an additive pump 504. The additive feed pipeline 5 is also provided with a pressure sensor 3 505, and the pressure sensor 3 505 is electrically connected to the controller.

[0025] The emulsion polymerization reactor 1 is also provided with a PVDF resin outlet pipeline 7 and a vent pipeline 8. The PVDF resin outlet pipeline 7 is provided with a switch control valve 701, and the vent pipeline 8 is provided with a vent cut-off valve 801;

[0026] The inhibitor tank 2 is connected to a pressure sensor 201, which is electrically connected to the controller. The inhibitor tank 2 is also connected to a high-pressure nitrogen cylinder 11 through a nitrogen input pipeline 10. A high-pressure nitrogen cylinder gas source valve 1101 is provided on the nitrogen input pipeline 10, and the high-pressure nitrogen cylinder gas source valve 1101 is electrically connected to the controller.

[0027] A measured amount of inhibitor is added to the inhibitor tank 2 in advance, the inlet of the inhibitor tank 2 is connected to a 13MPa high-pressure nitrogen cylinder 11, and the outlet is connected to the emulsion polymerization kettle 1. VDF, reaction aids and pure water from a diaphragm compressor are introduced into the emulsion polymerization kettle 1, and the temperature and pressure of the reaction system are monitored. When the pressure or temperature in the emulsion polymerization kettle 1 is too high, the shut-off valve 403 (VDF feed shut-off valve) is closed by interlock, the venting shut-off valve is opened by interlock, the gas source valve of the 13MPa high-pressure nitrogen cylinder is automatically opened by interlock, and the inhibitor discharge valve is automatically opened, so that the inhibitor is quickly added to prevent the reaction from proceeding and reduce the reaction risk.

[0028] Although the present invention is described in detail by referring to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person skilled in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A system for rapidly injecting inhibitor into a PVDF polymerization reactor to terminate the reaction, characterized in that: The invention comprises a controller and an emulsion polymerization kettle (1) and an inhibitor tank (2) connected by pipelines, wherein the emulsion polymerization kettle is connected to a balance tank (3) by pipelines, and the emulsion polymerization kettle (1) is also provided with a VDF feed pipeline (4), an auxiliary agent feed pipeline (5) and a pure water feed pipeline (6); The pure water feed pipeline (6) is provided with a flow sensor 1 (601) and a switch control valve 1 (602), and the flow sensor 1 (601) and the switch control valve 1 (602) are both electrically connected to the controller; The VDF feed pipeline (4) is provided with a flow sensor 2 (401), a regulating valve (402), a shut-off valve 1 (403), a switch control valve 2 (404) and a pressure sensor 1 (405), and the flow sensor 2 (401), the regulating valve (402), the shut-off valve 1 (403), the switch control valve 2 (404) and the pressure sensor 1 (405) are all electrically connected to the controller; The auxiliary agent feeding pipeline (5) is provided with a switch control valve 3 (501) and a flow sensor 2 (502), and the switch control valve 3 (501) and the flow sensor 2 (502) are both electrically connected to the controller; The emulsion polymerization kettle (1) is also provided with a PVDF resin outlet pipeline (7) and a venting pipeline (8), and the PVDF resin outlet pipeline (7) is provided with a switch control valve four (701); The polymerization inhibitor tank (2) is connected to a second pressure sensor (201), which is electrically connected to a controller. The polymerization inhibitor tank (2) is also connected to a high-pressure nitrogen cylinder (11) via a nitrogen input pipeline (10), and a high-pressure nitrogen cylinder gas source valve (1101) is provided on the nitrogen input pipeline (10), which is electrically connected to the controller.

2. The system for terminating the reaction of the PVDF polymerization kettle by rapidly injecting an inhibitor as claimed in claim 1, characterized in that: A pure water filter (603) is provided on the pure water feed pipeline (6).

3. The system for terminating the reaction of the PVDF polymerization kettle by rapidly injecting an inhibitor as claimed in claim 1, characterized in that: The venting pipeline (8) is provided with a venting shut-off valve (801).

4. The system for terminating the reaction of the PVDF polymerization kettle by rapidly injecting an inhibitor as claimed in claim 1, characterized in that: A polymerization inhibitor discharge valve (12) is arranged on the pipeline between the emulsion polymerization kettle (1) and the polymerization inhibitor tank (2), and the polymerization inhibitor discharge valve (12) is electrically connected to the controller.

5. The system for terminating the reaction of the PVDF polymerization kettle by rapidly injecting an inhibitor as claimed in claim 1, characterized in that: One end of the auxiliary agent feeding pipeline (5) away from the emulsion polymerization kettle (1) is connected to the auxiliary agent barrel (503), and an auxiliary agent pump (504) is arranged on the auxiliary agent feeding pipeline (5).

6. The system for terminating the reaction of the PVDF polymerization kettle by rapidly injecting an inhibitor as claimed in claim 1, characterized in that: A pressure sensor 3 (505) is also provided on the auxiliary agent feeding pipeline (5), and the pressure sensor 3 (505) is electrically connected to the controller.

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