Polyvinyl chloride polymerizer feeding system

Abstract

This invention discloses a feeding system for a polyvinyl chloride (PVC) polymerization reactor, relating to the field of PVC production technology. The system includes: a polymerization reactor, a deionized water supply unit, an additive supply unit, and a distributor. The deionized water supply unit includes a deionized water tank and a deionized water pump connected to the tank outlet. The additive supply unit includes a dispersant pump, an initiator pump, and a pH agent pump, with their outlet pipelines connected in parallel. The distributor's inlet is connected to the outlet of the deionized water pump and the parallel outlet pipeline of the additive supply unit, respectively, for mixing materials. A feeding port is located at the top of the polymerization reactor, connected to the distributor's outlet. The deionized water output from the deionized water pump carries the dispersant, initiator, and pH agent from the distributor, and they all enter the polymerization reactor through the single feeding port at the top. This system simplifies the piping layout, shortens the feeding time, and improves safety.

Description

Technical Field

[0001] This invention relates to the field of polyvinyl chloride (PVC) production technology. Background Technology

[0002] Polyvinyl chloride (PVC) is an important general-purpose synthetic resin widely used in construction, pipe manufacturing, and packaging. In the suspension polymerization process of PVC, the feeding system of the polymerization reactor is a crucial factor determining production efficiency and product quality. Traditional feeding processes typically follow a fixed sequence: first, deionized water is added to the polymerization reactor as a continuous phase; then, dispersants, pH adjusters, initiators, and other additives are added sequentially; finally, vinyl chloride monomer is added, and the polymerization reaction is initiated by heating. During this process, the four raw and auxiliary materials—deionized water, dispersant, pH adjuster, and initiator—enter the polymerization reactor through their respective independent pipelines, with four independent inlets located at the top of the reactor. This parallel design with multiple pipelines and inlets is a long-standing standard configuration in the industry.

[0003] However, the aforementioned traditional feeding system has significant drawbacks in actual operation. First, because the four raw and auxiliary materials must be added sequentially through their respective pipelines, the entire feeding process is time-consuming, directly impacting the turnover efficiency of the polymerization reactor, reducing the equipment utilization rate of a single reactor, and thus limiting the increase in production capacity. Second, the four independent inlets at the top of the polymerization reactor mean that more valves, flanges, and connectors are required. According to risk assessment standards in the petrochemical industry, each flange connection point is a potential leak source. Too many pipe openings not only increase the complexity of daily maintenance but also significantly increase the risk of vinyl chloride monomer leakage. As a flammable and explosive substance, vinyl chloride leakage can easily cause fires or explosions, posing a serious threat to production safety.

[0004] Existing technologies have attempted some improvements. For example, Chinese patent CN102863570B discloses a feeding process for a 70 cubic meter polymerization reactor used to produce polyvinyl chloride (PVC). This process involves adding a buffer to the deionized water main, starting the deionized water feed pump to introduce room temperature water from the bottom of the reactor, and simultaneously starting the monomer feed pump to feed from the top of the reactor. Pre-weighed dispersant and initiator are also pumped from the weighing tank from the bottom of the reactor. This process uses cold water feeding, which saves energy to some extent, reduces pump requirements, and saves feeding time. However, this scheme still retains multiple feeding paths—deionized water from the bottom, monomer from the top, and dispersant and initiator from the bottom—requiring multiple feed ports at the top and bottom of the reactor. This multi-port feeding design does not substantially reduce the number of ports in the polymerization reactor, resulting in a large number of flange connection points and failing to effectively control the risk of vinyl chloride monomer leakage. Therefore, how to further simplify the feeding process, reduce the number of pipe openings at the top of the polymerization reactor, and reduce safety risks while improving feeding efficiency remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a polyvinyl chloride polymerization reactor feeding system.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0007] A polyvinyl chloride polymerization reactor feeding system includes: a polymerization reactor, a deionized water supply unit, an additive supply unit, and a distributor; The deionized water supply unit includes a deionized water tank and a deionized water pump connected to the outlet of the deionized water tank; The auxiliary agent supply unit includes a dispersant pump, an initiator pump, and a pH agent pump, and the outlet pipelines of the dispersant pump, initiator pump, and pH agent pump are connected in parallel. The inlet of the distributor is connected to the outlet of the deionized water pump and the parallel outlet pipeline of the additive supply unit, respectively, for mixing the dispersant, initiator and pH agent with the deionized water; The top of the polymerization reactor is provided with a feeding port, which is connected to the outlet of the distributor; The deionized water pump outputs deionized water that carries the dispersant, initiator, and pH agent from the distributor and enters the polymerization reactor together through the single feed port at the top of the polymerization reactor.

[0008] In this scheme, water from the deionized water tank is pumped to the distributor, while the dispersant pump, initiator pump, and pH agent pump also pump their respective additives to the distributor via parallel pipelines. Inside the distributor, the deionized water mixes with the three additives, and the flushing force of the deionized water carries the mixed material through a single feed port at the top of the polymerization reactor into the reactor. By connecting multiple additive pipelines in parallel to the distributor, only one feed port at the top of the reactor is needed to add all four materials, significantly simplifying the pipeline layout, shortening the feeding time, and improving the utilization rate of the polymerization reactor. Furthermore, the reduced number of top feed ports effectively lowers the risk of vinyl chloride monomer leakage.

[0009] Furthermore, the outlet pipelines of the dispersant pump, initiator pump, and pH agent pump are all equipped with auxiliary check valves; the outlet pipeline of the deionizer pump is equipped with a feed main check valve.

[0010] The above scheme involves installing auxiliary check valves on the outlet pipelines of the dispersant pump, initiator pump, and pH agent pump, and installing a feed main check valve on the outlet pipeline of the deionized water pump. When the pump stops working, the check valves automatically close to prevent material backflow.

[0011] Furthermore, the deionized water pump is linked and controlled with the dispersant pump, initiator pump, and pH agent pump to ensure that the injection of deionized water is synchronized with the injection of dispersant, initiator, and pH agent.

[0012] The above-described scheme utilizes a control system to simultaneously start or synchronously operate the deionized water pump, dispersant pump, initiator pump, and pH agent pump, achieving coordinated injection of deionized water and the three additives. The technical advantage of this scheme is that it ensures the additives are promptly flushed and carried away by the deionized water, preventing them from remaining or depositing in the distributor. Simultaneously, synchronous feeding further reduces the overall feeding time, improving production efficiency.

[0013] Furthermore, the distributor is provided with a main conveying line connected to the outlet of the decoupled water pump, and an additive feed line connected to the parallel outlet line of the additive supply unit. The outlet of the additive feed line flows into the main conveying line in a tangential inflow manner. The distributor is provided with a fusion chamber at its end. The main conveying line is spiral in shape and its end enters the fusion chamber. The end of the fusion chamber is connected to the feeding port through a pipe.

[0014] In the above scheme, deionized water enters the distributor via the main conveying line, while the various additives flow tangentially into the main conveying line through the additive feed line, forming a swirling flow to promote initial mixing. Subsequently, the mixture flows through the spiral conveying main line into the fusion chamber, where it achieves thorough mixing under the buffering effect of the spiral flow and the fusion chamber. The tangential flow and spiral flow channel enhance the turbulent mixing effect, improve the mixing uniformity of additives and deionized water, thereby helping to stabilize the polymerization reaction process and improve product quality.

[0015] Furthermore, the bottom end of the fusion chamber is provided with a sweeping port, which is connected to the deionizer water tank through a pumping pipe, and the sweeping port is provided with at least two individuals facing different directions.

[0016] The above method involves introducing deionized water through a pumping pipeline to purge the bottom of the fusion chamber from multiple angles. This effectively removes any additive residues that may have deposited at the bottom of the fusion chamber, preventing blockages caused by material accumulation or batch-to-batch cross-contamination. The multi-directional design also ensures thorough purging without blind spots, improving cleaning efficiency and system reliability.

[0017] Furthermore, the diameter of the fusion cavity is increased at the connection point with the main conveying line through a reducing joint, the corner of the pipe leading from the fusion cavity to the feeding port is rounded, and the inner wall of the distributor is coated with a polytetrafluoroethylene non-stick coating combined with mirror polishing.

[0018] The above solution involves using a reducing joint at the inlet of the fusion chamber to increase the diameter, thereby reducing flow velocity and promoting mixing; rounded corners at the outlet pipe reduce flow resistance; and a polytetrafluoroethylene (PTFE) anti-stick coating is applied to the inner wall of the distributor, followed by mirror polishing. The reducing diameter design extends the residence time of materials in the fusion chamber to enhance mixing, while the rounded corners reduce material adhesion and retention. The anti-stick coating combined with mirror polishing effectively prevents additive adhesion, reducing cleaning frequency and maintenance difficulty.

[0019] Furthermore, a safety valve interface is provided on one side of the fusion cavity. The safety valve interface has a built-in pressure sensor, which is electrically connected to an alarm. The safety valve interface is connected to an accident handling system.

[0020] The above solution utilizes a built-in pressure sensor to monitor the internal pressure in real time. When the pressure exceeds a set threshold, an alarm is triggered to alert the operator, and the overpressured material is simultaneously discharged into the emergency response system through a safety valve. This achieves online monitoring of the distributor's internal pressure and automatic response to abnormal operating conditions, effectively preventing overpressure accidents caused by pipeline blockage or valve malfunction.

[0021] Furthermore, the distributor is surrounded by a jacketed insulation layer, and circulating insulation liquid is circulated inside the jacketed insulation layer.

[0022] The above scheme maintains a stable temperature of the material in the distributor through heat exchange, preventing changes in the viscosity of the additives or crystallization due to changes in ambient temperature, and ensuring that the material is always in a suitable flow state.

[0023] Furthermore, a liquid level sensor is provided inside the fusion chamber, and the liquid level sensor is linked and controlled with the deionizer pump, the dispersant pump, the initiator pump, and the pH agent pump.

[0024] Through the above scheme, the liquid level sensor in the fusion chamber detects the material liquid level in real time and transmits the signal to the control system. When the liquid level is abnormal (such as too high or too low), the control system automatically adjusts the operating status of the deionizer pump and each auxiliary agent pump. The technical effect of this scheme is to prevent overflow or cavitation of the fusion chamber caused by pump flow imbalance, ensuring the continuity and stability of the feeding process.

[0025] The beneficial effects of this invention are as follows: 1. This invention features a simple structure. Water from the deionized water tank is pumped to the distributor via a deionized water pump. Simultaneously, the dispersant pump, initiator pump, and pH agent pump also pump their respective additives to the distributor via parallel pipelines. Inside the distributor, the deionized water and the three additives combine, and the flushing force of the deionized water carries the mixed material through a single feed port at the top of the polymerization reactor into the reactor. By connecting multiple additive pipelines in parallel to the distributor, only one feed port at the top of the reactor is needed to add all four materials, significantly simplifying the pipeline layout, shortening the feeding time, and improving the utilization rate of the polymerization reactor. Furthermore, the reduced number of top feed ports effectively lowers the risk of vinyl chloride monomer leakage. 2. The built-in pressure sensor monitors the internal pressure in real time. When the pressure exceeds the set threshold, an alarm is triggered to warn the operator. Simultaneously, the overpressured material is discharged into the accident handling system through the safety valve interface. This achieves online monitoring of the distributor's internal pressure and automatic response to abnormal operating conditions, effectively preventing overpressure accidents caused by pipeline blockage or valve failure. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a structural diagram of the distributor part of the present invention; Reference numerals: 1. Deionizer tank; 2. Deionizer pump; 3. Feed main check valve; 4. Distributor; 5. Polymerization reactor; 6. Dispersant pump; 7. Initiator pump; 8. pH pump; 9. Additive check valve; 10. Main conveying line; 11. Additive feed line; 12. Fusion chamber; 13. Feed port; 14. Purging port; 15. Safety valve interface; 16. Pressure sensor; 17. Alarm; 18. Jacketed insulation layer; 19. Liquid level sensor. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] Example 1 like Figure 1 As shown in the figure, this embodiment discloses a polyvinyl chloride (PVC) polymerization reactor feeding system, which aims to solve the problems of low feeding efficiency, poor equipment utilization, and high risk of vinyl chloride monomer leakage caused by multiple pipelines and feeding ports 13 in the traditional PVC polymerization reactor feeding process. At the same time, it realizes the uniform mixing and stable delivery of deionized water and various additives, ensuring the continuity and safety of the polymerization reaction.

[0030] This PVC polymerization reactor feeding system mainly consists of a polymerization reactor 5, a deionized water supply unit, an additive supply unit, and a distributor 4. These units work together to achieve simultaneous single-port feeding of four materials. The specific structure and operation are as follows: The deionized water supply unit includes a deionized water tank 1 and a deionized water pump 2. The inlet of the deionized water pump 2 is connected to the outlet of the deionized water tank 1, providing power for the delivery of deionized water. The additive supply unit consists of a dispersant pump 6, an initiator pump 7, and a pH agent pump 8. The outlet pipelines of the dispersant pump 6, initiator pump 7, and pH agent pump 8 are connected in parallel, allowing the three additives to be simultaneously delivered to the subsequent distributor 4. Each of the dispersant pump 6, initiator pump 7, and pH agent pump 8 has a separate additive check valve 9 on its outlet pipeline, and a corresponding feed main check valve 3 is installed on the outlet pipeline of the deionized water pump 2. All check valves automatically close when the pumps stop working, effectively preventing material backflow from the polymerization reactor 5 into the pipelines, avoiding material contamination and abnormal pipeline pressure.

[0031] As the core component for material mixing, the distributor 4 has its inlet connected to the outlet of the deionizer pump 2 and the parallel outlet pipeline of the additive supply unit, respectively. The outlet of the distributor 4 is connected to the only feeding port 13 opened at the top of the polymerization reactor 5, so as to realize the single-port feeding of the mixed materials into the reactor. The distributor 4 integrates a main conveying line 10 and an additive feed line 11. The main conveying line 10 is seamlessly connected to the outlet of the deionized water pump 2, while the additive feed line 11 is connected to the parallel outlet line of the additive supply unit. The outlet of the additive feed line 11 flows tangentially into the main conveying line 10, allowing the additive to form a swirling flow with the deionized water upon entry, achieving initial mixing. The main conveying line 10 is designed as a spiral, with its end leading to the fusion chamber 12 at the end of the distributor 4. The fusion chamber 12 provides ample mixing and buffering space for the material, and its end is connected to the feed port 13 of the polymerization reactor 5 via a pipe. The spiral-shaped main conveying line 10 extends the material mixing path, enhances the turbulent mixing effect, and allows the deionized water and the three additives to be uniformly fused before entering the polymerization reactor 5.

[0032] To achieve intelligent linkage and stable operation of the system, the deionized water pump 2, dispersant pump 6, initiator pump 7, and pH agent pump 8 adopt a linkage control method. The control system can simultaneously start multiple pumps or operate synchronously according to a preset sequence, ensuring that the injection of deionized water and the injection of the three additives are synchronized. This allows the additives to be promptly flushed and carried away by the deionized water, preventing them from accumulating and settling in the distributor 4, and further reducing the feeding time. A level sensor 19 is also installed in the fusion chamber 12. This level sensor 19 forms a linkage control system with the deionized water pump 2 and each additive pump. The level sensor 19 can detect the material level in the fusion chamber 12 in real time. When abnormal conditions such as excessively high or low levels are detected, a signal is transmitted to the control system, which automatically adjusts the operating rate of each pump to prevent overflow or cavitation in the fusion chamber 12, ensuring the continuity of the feeding process.

[0033] To address the issues of material residue, flow resistance, temperature stability, and safety protection in distributor 4, this system incorporates multiple optimized designs: At least two sweeping ports 14 facing different directions are located at the bottom of the fusion chamber 12. These ports 14 are connected to the deionizer water tank 1 via a pumping pipeline. After feeding, the deionizer water tank 1 can supply deionizer water to the sweeping ports 14, achieving multi-angle, dead-angle-free sweeping of the bottom of the fusion chamber 12, thoroughly removing additive residues and preventing material accumulation, blockage, or batch-to-batch cross-contamination. The connection between the fusion chamber 12 and the main conveying line 10 uses a reducing joint to increase the diameter, reducing the material flow rate into the fusion chamber 12 and extending the material residence time to enhance mixing. The corner of the pipe leading from the fusion chamber 12 to the feeding port 13 is rounded to effectively reduce material flow resistance and prevent material from adhering to the wall at the corner. All inner walls of distributor 4 are treated with a polytetrafluoroethylene anti-stick coating combined with mirror polishing, providing dual protection against additive adhesion through both material and structural means, reducing equipment cleaning frequency and maintenance difficulty.

[0034] The distributor 4 is surrounded by a jacketed insulation layer 18, through which circulating insulation liquid can be introduced. This insulation layer maintains a stable internal temperature for the distributor 4 through heat exchange, preventing changes in additive viscosity and crystallization due to ambient temperature variations. This ensures the material remains in a suitable flow state, guaranteeing effective mixing and conveying. A safety valve interface 15 is also provided on one side of the fusion chamber 12. A pressure sensor 16 is built into the safety valve interface 15, electrically connected to an alarm 17. The safety valve interface 15 is also connected to the workshop accident handling system. The pressure sensor 16 monitors the material pressure within the fusion chamber 12 in real time. When the pressure exceeds a set threshold, the alarm 17 is immediately triggered to warn the operator. Simultaneously, the safety valve interface 15 automatically opens, discharging the overpressured material into the accident handling system, thus achieving overpressure relief and effectively preventing overpressure rupture and material leakage accidents caused by pipeline blockage or valve malfunction.

[0035] The overall workflow of the polyvinyl chloride (PVC) polymerization reactor feeding system is as follows: The control system is started, and the deionized water pump 2, dispersant pump 6, initiator pump 7, and pH agent pump 8 operate synchronously. The deionized water in the deionized water tank 1 is pumped by the deionized water pump 2 to the main conveying line 10 of the distributor 4. The dispersant, initiator, and pH agent are pumped by their respective pump bodies and parallel pipelines to the auxiliary agent feed line 11 of the distributor 4. The auxiliary agents flow tangentially into the main conveying line 10 and form a swirling flow with the deionized water. After being intensified by the spiral conveying line 10, they enter the fusion chamber 12, where they are fully and uniformly fused. The level sensor 19 and pressure sensor 16 in the fusion chamber 12 monitor the operating parameters in real time to ensure that the material level and pressure are within the normal range. The mixed material then enters the interior of the polymerization reactor 5 through the single feeding port 13 at the top of the reactor, completing the feeding process. After the feeding is completed, all pumps stop working, and all kinds of check valves automatically close to prevent material backflow. At the same time, the deionized water tank 1 delivers deionized water to the purging port 14 of the fusion chamber 12 to purge and clean the fusion chamber 12 in all directions and remove material residue.

[0036] The PVC polymerization reactor feeding system in this embodiment, through pipeline integration and optimized design of distributor 4, changes the traditional multi-port feeding to single-port feeding, greatly simplifying the pipeline layout, reducing flange sealing points, and effectively reducing the risk of PVC monomer leakage. At the same time, it realizes the synchronous delivery and uniform mixing of deionized water and three additives, significantly shortening the feeding time and improving the equipment utilization rate of polymerization reactor 5. The design of various check valves, sensors, insulation layers and safety pressure relief structures further ensures the stability, safety and reliability of system operation, effectively improving the efficiency and product quality of PVC polymerization production.

[0037] It should be noted that the connection relationships of components not specifically mentioned in this application are all assumed to be based on existing technology. Since they do not involve the inventive point and are commonly used in existing technology, the structural connection relationships are not described in detail.

Claims

1. A feeding system for a polyvinyl chloride polymerization reactor, characterized in that, include: Polymerization reactor (5), deionized water supply unit, additive supply unit, distributor (4); The deionized water supply unit includes a deionized water tank (1) and a deionized water pump (2) connected to the outlet of the deionized water tank (1); The auxiliary agent supply unit includes a dispersant pump (6), an initiator pump (7), and a pH agent pump (8), and the outlet pipelines of the dispersant pump (6), the initiator pump (7), and the pH agent pump (8) are connected in parallel; The inlet of the distributor (4) is connected to the outlet of the deionized water pump (2) and the parallel outlet pipeline of the additive supply unit, respectively, for mixing the dispersant, initiator and pH agent with the deionized water; The top of the polymerization reactor (5) is provided with a feeding port (13), which is connected to the outlet of the distributor (4); The deionized water output by the deionized water pump (2) carries the dispersant, initiator and pH agent from the distributor (4) and enters the interior of the polymerization reactor (5) together through the only feed port (13) at the top of the polymerization reactor (5).

2. The polyvinyl chloride polymerization reactor feeding system according to claim 1, characterized in that, The outlet pipelines of the dispersant pump (6), the initiator pump (7) and the pH pump (8) are all equipped with auxiliary check valves (9); the outlet pipeline of the deionizer pump (2) is equipped with a feed main check valve (3).

3. The polyvinyl chloride polymerization reactor feeding system according to claim 1, characterized in that, The deionized water pump (2) is linked with the dispersant pump (6), initiator pump (7) and pH agent pump (8) to ensure that the injection of deionized water is synchronized with the injection of dispersant, initiator and pH agent.

4. The polyvinyl chloride polymerization reactor feeding system according to claim 1, characterized in that, The distributor (4) is provided with a main conveying line (10) connected to the outlet of the decoupled water pump (2), and an auxiliary feed line (11) connected to the parallel outlet line of the auxiliary supply unit. The outlet of the auxiliary feed line (11) flows into the main conveying line (10) in a tangential inflow manner. The distributor (4) is provided with a fusion chamber (12) at its end. The main conveying line (10) is spiral in shape and its end enters the fusion chamber (12). The end of the fusion chamber (12) is connected to the feed port (13) through a pipe.

5. The polyvinyl chloride polymerization reactor feeding system according to claim 4, characterized in that, The bottom end of the fusion chamber (12) is provided with a sweeping port (14), which is connected to the deionizer water tank (1) through a pumping pipe. The sweeping port (14) is provided with at least two individuals facing different directions.

6. The polyvinyl chloride polymerization reactor feeding system according to claim 4, characterized in that, The diameter of the fusion cavity (12) is increased by a reducing joint at the connection point with the main conveying line (10). The corner of the pipe from the fusion cavity (12) to the feeding port (13) is rounded. The inner wall of the distributor (4) is coated with a polytetrafluoroethylene non-stick coating and mirror polishing.

7. The polyvinyl chloride polymerization reactor feeding system according to claim 6, characterized in that, The fusion chamber (12) is provided with a safety valve interface (15) on one side. The safety valve interface (15) has a built-in pressure sensor (16) and the pressure sensor (16) is electrically connected to an alarm (17). The safety valve interface (15) is connected to an accident handling system.

8. The polyvinyl chloride polymerization reactor feeding system according to claim 4, characterized in that, The distributor (4) is surrounded by a jacketed insulation layer (18), and circulating insulation liquid is introduced into the jacketed insulation layer (18).

9. The polyvinyl chloride polymerization reactor feeding system according to claim 4, characterized in that, The fusion chamber (12) is equipped with a liquid level sensor (19), which is linked and controlled with the deionizer pump (2), the dispersant pump (6), the initiator pump (7), and the pH agent pump (8).

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