A nitrogen purging device for FEP polymerization reactor

Abstract

A nitrogen purging device for an FEP polymerization reactor, relating to the field of fluoropolymer production technology, achieves nitrogen substitution for monomers and optimizes the process through a specific gas distribution mechanism, solving the problems of monomer waste and safety risks during leak detection in the FEP polymerization reactor purging process. The device includes a nitrogen source connected by pipelines, a gas distribution mechanism, a polymerization reactor, a monomer supply source, and a vacuum pump. The gas distribution mechanism includes a distribution chamber; a vent pipe with a vent control valve at its bottom is also provided; the distribution chamber further includes multiple inlets and outlets, each connected to an on / off control valve; the nitrogen source and monomer supply source are connected to the inlets via inlet pipes; the outlets are connected to the vacuum pump via outlet pipes; the polymerization reactor is connected to the distribution chamber via reactor pipelines; and an online oxygen content monitor is installed on the polymerization reactor.

Description

Technical Field

[0001] This utility model relates to the field of fluoropolymer production technology, and in particular to a nitrogen purging device for an FEP polymerization reactor. Background Technology

[0002] In the production of FEP (perfluoroethylene propylene copolymer), the polymerization reaction is extremely sensitive to oxygen content. Therefore, before the reaction begins, the polymerization reactor and its connecting pipelines must be thoroughly purged and leak-checked to establish an absolutely oxygen-free safe reaction environment.

[0003] Currently, the replacement process commonly used in the industry has significant defects. Its standard procedure is as follows: First, the reactor is evacuated and replaced twice using a vacuum pump. The first replacement requires a large amount of expensive FEP monomer to replace the air in the reactor. Only after the second replacement and the oxygen content is initially qualified can the initial monomer be added for subsequent reactions.

[0004] Using high-value raw materials as a replacement medium is extremely uneconomical. Taking this device as an example, this step alone wastes about 2.16 tons of monomers per month, which translates to a direct economic loss of more than 40,000 yuan. In the long run, the production cost is high. In addition, the process is complicated, and the entire process of evacuation, filling, and sampling analysis is repeated, which seriously restricts the equipment utilization rate and production pace.

[0005] On the other hand, when performing regular nitrogen purging and leak detection on the polymerization reactor pipeline, the current method requires temporary connection of a hose from the compressor inlet. This operating mode has several drawbacks: First, the connection, disassembly, and storage of the hose consume a lot of manpower and time, resulting in low maintenance efficiency; second, frequent manual connection operations have poor stability and are prone to instantaneous leakage of high-pressure nitrogen due to loose connections, poor sealing, or operational errors. This not only poses serious safety risks such as suffocation and injury to on-site operators, but may also create hidden safety hazards due to incomplete leak detection. Therefore, the entire replacement and leak detection process has become a key bottleneck restricting the FEP unit from achieving cost reduction, efficiency improvement, and inherent safety enhancement. Utility Model Content

[0006] I. Technical problems to be solved This invention addresses the shortcomings of existing technologies by proposing a nitrogen purging device for FEP polymerization reactors. Through a specific gas distribution mechanism, it achieves nitrogen substitution for monomers and optimizes the process integration, thus solving the problems of monomer waste and safety risks during leak detection in the FEP polymerization reactor purging process.

[0007] II. Specific Technical Solutions A nitrogen purging device for an FEP polymerization reactor includes a nitrogen source connected by pipelines, a gas distribution mechanism, a polymerization reactor, a monomer supply source, and a vacuum pump. The gas distribution mechanism includes a distribution chamber; a venting pipeline is provided at the bottom of the distribution chamber, and a venting control valve is provided at the bottom of the venting pipeline; the distribution chamber also includes multiple gas inlets and outlets, and on / off control valves are connected to the gas inlets and outlets; the nitrogen source and the monomer supply source are connected to the gas inlets via gas inlet pipelines; the gas outlets are connected to the vacuum pump via gas outlet pipelines; the polymerization reactor is connected to the distribution chamber via reactor pipelines; and an online oxygen content monitor is installed on the polymerization reactor.

[0008] Implementation principle and working principle: This solution incorporates a gas distribution mechanism with a central distribution chamber. This mechanism connects the nitrogen and monomer supply sources in parallel to the same system and, through valve control, forms a flexibly switchable gas path with the vacuum pump and polymerization reactor. An online oxygen content monitor is used to monitor the replacement effect in real time, while a venting pipeline is used to remove residual gas from the distribution mechanism before operation, preventing cross-contamination. By integrating the nitrogen path into the system, inexpensive nitrogen can be used instead of expensive monomer for the initial evacuation and replacement. When the polymerization reactor completes subsequent feeding, opening the venting control valve ensures that even if the upstream valve leaks, the high-pressure monomer will be safely released to the atmosphere through the venting pipeline instead of entering the nitrogen network, completely eliminating this major safety hazard. The integrated gas path and online oxygen content monitoring improve production efficiency and reduce labor intensity.

[0009] Preferably, a check valve is installed on the inlet pipe connecting the nitrogen source and the corresponding inlet. The advantage of this preferred option is that by adding a check valve to the nitrogen pipe, its one-way flow characteristic serves as a safety redundancy, preventing monomers or other media in the polymerization reactor from flowing back into the nitrogen source pipe under abnormal conditions, thus further strengthening the safety barrier of the system.

[0010] Preferably, the system also includes a controller; the signal input terminal of the controller is electrically connected to the online oxygen content monitor; the output terminal of the controller is electrically connected to the evacuation control valve and the on / off control valve, respectively. The beneficial effect of this preferred embodiment is that by introducing the controller, a closed-loop control circuit is formed with the online oxygen content monitor and each control valve, realizing automated control. The system can automatically control the opening and closing of the valves according to the real-time oxygen content data, and automatically complete the "evacuation-nitrogen filling" cycle until it meets the requirements. This greatly reduces human intervention, avoids human error, ensures the consistency of process execution, and further improves production efficiency and safety.

[0011] Preferably, pressure gauges are installed on both the inlet and outlet pipes, and the pressure gauges are electrically connected to the signal input terminal of the controller. The controller is configured to output a leakage alarm signal based on the pressure difference between the inlet and outlet of the same pipe. The advantages of this preferred embodiment are that by installing pressure gauges on the pipes and having the controller calculate and compare the pressure difference between the inlet and outlet of the same pipe in real time, the frequency of traditional pressure holding and leak detection operations is reduced. The controller can monitor the pipe sealing in real time, and immediately issue an alarm if the pressure difference is abnormal. This achieves a leap from periodic shutdown for leak detection to online real-time monitoring, improving equipment reliability and safety, and avoiding potential production interruptions.

[0012] Preferably, the online oxygen content monitor is a multi-point online monitor, wherein at least one measuring point of the multi-point online monitor is configured to measure the oxygen content in the inlet pipeline corresponding to the polymerization reactor. The beneficial effect of this preferred option is that it upgrades the online oxygen content monitor to a multi-point online monitor, extending the monitoring points from the reactor body to the critical inlet pipeline. When the system oxygen content is unqualified, by comparing the data from different measuring points, it is possible to quickly determine whether the problem stems from the reactor's own sealing or from insufficient purity of the nitrogen used for replacement or pipeline leakage, greatly shortening the troubleshooting time.

[0013] Preferably, a gas storage tank and a dryer are sequentially connected to the nitrogen source's inlet pipeline. The advantage of this preferred embodiment is that by adding a gas storage tank and a dryer sequentially to the nitrogen source pipeline, the gas storage tank can buffer pressure fluctuations and ensure a stable nitrogen supply; the dryer can remove moisture from the nitrogen, preventing moisture from entering the polymerization reactor and affecting the quality of the FEP product, such as causing defects like bubbles. This improves the stability of the entire process system and the consistency of the final product's quality.

[0014] The beneficial effects of this utility model are as follows: 1. This solution fundamentally solves the core problem of waste of original process monomers by completely replacing expensive monomers with inexpensive nitrogen for the first replacement; the direct economic benefits are significant. Taking the current scale as an example, it can save about RMB 43,200 per month; at the same time, the integrated gas path design eliminates the cumbersome manual connection process, greatly improves the efficiency of replacement and leak detection operations, and shortens the production preparation time.

[0015] 2. The solution, through the physical design of "always open venting pipeline", fundamentally eliminates the risk of high-pressure cells entering the nitrogen pipeline network; the added check valve forms a second safety barrier to prevent media backflow; and the automatic alarm function based on real-time pressure monitoring transforms the traditional passive shutdown and leak detection into active online monitoring, constructing a preventive safety system that comprehensively reduces safety risks.

[0016] 3. By integrating an online oxygen analyzer and controller, automated closed-loop control of the replacement process is achieved, avoiding human error and ensuring the accuracy and consistency of process execution. The multi-point monitoring function can not only quickly locate the leak source, but also work in conjunction with a stable dry nitrogen source to ensure that the reaction environment is always in the optimal state of being anhydrous and oxygen-free, thereby stabilizing and improving the quality of the final product. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the nitrogen purging device for the FEP polymerization reactor of this utility model.

[0018] Explanation of reference numerals in the attached figures: 1. Nitrogen source, 2. Gas distribution mechanism, 201. Distribution chamber, 202. Exhaust pipe, 2020. Exhaust control valve, 203. Inlet, 2030. Check valve, 2031. Outlet, 204. Outlet pipe, 2040. On / off control valve, 205. Polymerization reactor, 3. Online oxygen content monitor, 301. Monomer supply source, 4. Vacuum pump, 5. Controller, 6. Pressure gauge, 7. Gas storage tank, 8. Dryer. Detailed Implementation

[0019] The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings, so that the advantages and features of this utility model can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0020] like Figure 1 As shown: The present invention provides a nitrogen purging device for an FEP polymerization reactor, which mainly includes a nitrogen source 1, a gas distribution mechanism 2, a polymerization reactor 3, a monomer supply source 4, and a vacuum pump 5 connected by pipelines.

[0021] During implementation, the gas distribution mechanism 2 is the hub of the entire system, and it has a distribution chamber 201 inside. At the bottom of the distribution chamber 201, there is a vent pipe 202, and a vent control valve 2020 is installed on the pipe. This vent pipe 202 is kept open during the polymerization reaction as a safe discharge port, ensuring that even if the upstream valve leaks, the high-pressure monomer in the polymerization reactor 3 will be directly discharged to the atmosphere and will not flow back into the nitrogen pipeline, thereby eliminating this safety hazard.

[0022] The distribution chamber 201 is also equipped with multiple air inlets 203 and air outlets 204, each of which is connected to an on / off control valve 205 to control the on / off of the gas path. The nitrogen source 1 and the unit supply source 4 are respectively connected to the corresponding air inlets 203 through the air inlet pipe 2030. In particular, a check valve 2031, a gas storage tank 7 and a dryer 8 are connected in series on the air inlet pipe 2030 of the nitrogen source 1. The check valve 2031 can effectively prevent any medium from flowing back into the nitrogen source 1. The gas storage tank 7 is used to stabilize the gas supply pressure. The dryer 8 is used to ensure that the nitrogen entering the system is dry and to prevent moisture from affecting product quality.

[0023] Specifically, the outlet 204 of the distribution chamber 201 is connected to the vacuum pump 5 through the outlet pipe 2040; the polymerization reactor 3 is connected to the distribution chamber 201 through the reactor pipe, thus forming a complete evacuation path of "vacuum pump 5, gas distribution mechanism 2, polymerization reactor 3"; an online oxygen content monitor 301 is installed on the polymerization reactor 3. In this embodiment, the monitor is a multi-point online monitor. One measuring point monitors the gas inside the polymerization reactor 3, and the other measuring point is configured to measure the oxygen content of the nitrogen inlet pipe 2030, so as to quickly locate the source of the problem when the oxygen content is unqualified.

[0024] To further enhance automation, the system also includes a controller (such as a PLC or DCS). The controller's signal input is electrically connected to the online oxygen content monitor 301. Pressure gauges 6 are installed on the critical inlet and outlet pipelines 2030, transmitting signals to the controller. The controller's output is electrically connected to the vent control valve 2020 and all on / off control valves 205. The controller is programmed to automatically execute the replacement process based on feedback from the online oxygen content monitor 301. Simultaneously, it can calculate the pressure difference across the same pipeline in real time; if this difference exceeds a preset threshold, it indicates a leak and outputs an alarm signal.

[0025] The workflow of this utility model is as follows: Nitrogen purging stage: Start vacuum pump 5, open the on / off control valve 205 connecting the polymerization reactor 3 and vacuum pump 5, close other valves, and evacuate the polymerization reactor 3; after evacuating to absolute pressure, close the valve of vacuum pump 5, open the on / off control valve 205 of the nitrogen pipeline, and fill the polymerization reactor 3 with nitrogen to a slightly positive pressure; the controller automatically repeats this evacuation-nitrogen filling cycle according to the data of the online oxygen content monitor 301 until the oxygen content is qualified.

[0026] Monomer feeding stage: After the oxygen content is qualified, the polymerization reactor 3 is evacuated again; then the vacuum valve is closed, the valve of the monomer supply pipeline is opened, and the initial monomer is fed into the reactor.

[0027] Safe operating status: After entering the polymerization reaction stage, the vent control valve 2020 remains open, forming a permanent safe venting channel to ensure inherent safety; it should be noted that nitrogen source 1 and monomer supply source 4 can be steel cylinders storing the corresponding gases.

[0028] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims.

Claims

1. A nitrogen purging device for an FEP polymerization reactor, comprising a nitrogen source (1) connected by a pipeline, a gas distribution mechanism (2), a polymerization reactor (3), a monomer supply source (4), and a vacuum pump (5); characterized in that: The gas distribution mechanism (2) includes a distribution chamber (201); a venting pipe (202) is provided at the bottom of the distribution chamber (201), and a venting control valve (2020) is provided at the bottom of the venting pipe (202); the distribution chamber (201) also includes multiple air inlets (203) and air outlets (204), and on / off control valves (205) are connected to the air inlets (203) and air outlets (204); the nitrogen source (1) and the monomer supply source (4) are connected to the air inlets (203) through the air inlet pipe (2030); the air outlet (204) is connected to the vacuum pump (5) through the air outlet pipe (2040); the polymerization reactor (3) is connected to the distribution chamber (201) through the reactor pipe; and an online oxygen content monitor (301) is provided on the polymerization reactor (3).

2. The nitrogen purging device for the FEP polymerization reactor according to claim 1, characterized in that: A check valve (2031) is provided on the air inlet pipe (2030) that connects the nitrogen source (1) to the corresponding air inlet (203).

3. The nitrogen purging device for the FEP polymerization reactor according to claim 1, characterized in that: It also includes a controller; the signal input terminal of the controller is electrically connected to the online oxygen content monitor (301); the output terminal of the controller is electrically connected to the venting control valve (2020) and the on / off control valve (205) respectively.

4. The nitrogen purging device for the FEP polymerization reactor according to claim 3, characterized in that: Pressure gauges (6) are installed on both the intake pipe (2030) and the outlet pipe (2040), and the pressure gauges (6) are electrically connected to the signal input terminal of the controller; the controller is configured to output a leakage alarm signal based on the pressure difference between the intake and outlet ends of the same pipe.

5. The nitrogen purging device for the FEP polymerization reactor according to claim 3, characterized in that: The oxygen content online monitoring instrument (301) is a multi-point online monitoring instrument, and at least one measuring point of the multi-point online monitoring instrument is configured to measure the oxygen content of the gas inlet pipe (2030) corresponding to the polymerization reactor (3).

6. The nitrogen purging device for the FEP polymerization reactor according to claim 1, characterized in that: The nitrogen source (1) is connected in sequence to the air inlet pipe (2030) with a gas storage tank (7) and a dryer (8).

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