A polyvinyl caprolactam pH detection device

Abstract

The utility model provides a kind of polyvinyl hexanolactam pH value detection device, it includes reaction kettle, material sampling device and material conveying pipeline, reaction kettle has material outlet and material inlet, sampling device one end is inserted into reaction kettle through material outlet, sampling device other end is connected with the one end of material conveying pipeline, the other end of material conveying pipeline is connected with material inlet, pH value measurement structure is placed in detection buffer tank, material conveying pipeline sequentially transports the material to be detected that sampling device is taken out from reaction kettle to pressure relief buffer tank, detection buffer tank and pressurized buffer tank backflow to material inlet after.The utility model is through the three-stage design of pressure relief buffer tank, detection buffer tank, pressurized buffer tank, and pressure relief tank solves the security risk of high-pressure sampling, pressurized tank solves the risk of safe return, electrode is completely liberated from extreme working condition, prolongs its service life, and greatly reduces maintenance cost.

Description

Technical Field

[0001] This utility model relates to the field of chemical machinery technology, specifically to a polyvinyl caprolactam pH value detection device. Background Technology

[0002] In the synthesis of polyvinyl caprolactam, the pH value of the material inside the reactor is a key control parameter determining the degree of polymerization, product molecular weight distribution, and end-group structure. This cationic ring-opening polymerization reaction is highly pH sensitive, and the pH value of the internal material directly affects the reaction rate, product quality, and process safety. Traditional pH detection methods often employ offline sampling and analysis, i.e., extracting material samples from the reactor manually or mechanically, cooling and depressurizing them, and then transferring them to the laboratory for testing. However, this method has significant drawbacks: the detection results are severely delayed, failing to reflect real-time dynamic changes within the reactor, leading to untimely process control and easily causing problems such as reaction runaway and increased byproducts, especially affecting pH-sensitive polymerization, neutralization, and catalytic reactions.

[0003] In recent years, to address the limitations of offline detection, some companies have attempted to install online pH electrodes directly inside the reactor. However, this approach faces the following technical bottlenecks: 1. Insufficient environmental tolerance: The high temperature (often reaching 150~300℃), high pressure (several megapascals) and highly corrosive media environment inside the reactor will accelerate the aging of the electrode film and leakage of the reference liquid, resulting in a significant reduction in electrode life (usually less than 3 months) and a surge in maintenance costs. 2. Severe measurement interference: Vigorous stirring, bubbles or suspended particles can easily cause electrode surface contamination, measurement signal drift, and require frequent calibration or even shutdown for cleaning; 3. High safety risks: Directly exposed electrodes may cause material leakage due to seal failure, posing a significant safety hazard, especially in flammable and explosive systems.

[0004] Furthermore, while existing external circulation detection systems can partially alleviate the aforementioned problems, their complex piping designs (such as constant flow pumps and multi-stage valve assemblies) result in long response delays (typically exceeding 5 minutes), large dead volumes (residual materials affect subsequent batch production), and reliance on external cooling devices, significantly increasing energy consumption and floor space costs. To address these technical pain points, there is an urgent need to develop a pH detection system that balances real-time performance, reliability, and economy, ensuring process safety while overcoming electrode lifespan limitations and reducing maintenance costs to meet the pressing demands for efficient process control in fields such as fine chemicals and biopharmaceuticals. Therefore, existing technologies require further development. Utility Model Content

[0005] This invention provides a device for detecting the pH value of polyvinyl caprolactam, the specific implementation of which is as follows: A pH testing device for polyvinyl caprolactam includes a reaction vessel, a material sampling device, and a material conveying pipeline. The reaction vessel has a material outlet and a material inlet. One end of the sampling device is inserted into the reaction vessel through the material outlet, and the other end of the sampling device is connected to one end of the material conveying pipeline. The other end of the material conveying pipeline is connected to the material inlet. A pressure relief buffer tank, a detection flushing tank, and a pressure boosting buffer tank are sequentially arranged on the material conveying pipeline. A pH measuring structure is placed in the detection buffer tank. The material to be tested, taken from the reaction vessel by the sampling device, is sequentially transported to the pressure relief buffer tank, the detection flushing tank, and the pressure boosting buffer tank, and then returned to the material inlet.

[0006] A pH testing device for polyvinyl caprolactam includes a reaction vessel, a material sampling device, and a material conveying pipeline. The reaction vessel has a material outlet and a material inlet. One end of the sampling device is inserted into the reaction vessel through the material outlet, and the other end of the sampling device is connected to one end of the material conveying pipeline, the other end of which is connected to the material inlet. A pressure relief buffer tank, a detection flushing tank, and a pressurization buffer tank are sequentially arranged on the material conveying pipeline. A pH measuring structure is placed in the detection buffer tank. The material conveying pipeline transports the material to be tested taken from the reaction vessel by the sampling device to the pressure relief buffer tank, the detection flushing tank, and the pressurization buffer tank in sequence, and then returns it to the material inlet. A pressure regulating device is connected to the pressure relief buffer tank to adjust the pressure inside the tank.

[0007] Furthermore, a heat dissipation device is installed on the material conveying pipeline between the sampling device and the pressure relief buffer tank.

[0008] Furthermore, a first valve for controlling the material flow rate is installed on the material conveying pipeline between the heat dissipation device and the pressure relief buffer tank.

[0009] Furthermore, a first pressurization pipeline for supplying pressurized gas into the reactor is connected to the material conveying pipeline between the sampling device and the heat dissipation device, and a second valve is provided on the pressurization pipeline.

[0010] Furthermore, the pressure regulating mechanism includes a vacuum pumping device, a second pressurizing pipeline for supplying pressurized gas into the pressure relief buffer tank, and an exhaust pipeline for maintaining the pressure inside the pressure relief buffer tank at atmospheric pressure. The pressure relief buffer tank is connected to the vacuum pumping device through a first pipeline, and a third valve, a fourth valve, and a fifth valve are respectively installed on the first pipeline, the second pressurizing pipeline, and the exhaust pipeline.

[0011] Furthermore, the pressurized buffer tank is connected to a third pressurized pipeline for supplying pressurized gas into the pressurized buffer tank, and a first gate valve is installed on the third pressurized pipeline.

[0012] Furthermore, the pH measurement structure is a pH electrode.

[0013] Furthermore, a first control valve is installed on the material conveying pipeline between the pressure relief buffer tank and the detection buffer tank, and a second control valve is installed on the material conveying pipeline between the detection flushing tank and the pressurization buffer tank.

[0014] Furthermore, the material sampling device is a bottom-insertion tube, and a second gate valve is provided at the connection between the bottom-insertion tube and the material conveying pipeline.

[0015] Furthermore, a third gate valve is installed on the material conveying pipeline between the pressure buffer tank and the material inlet.

[0016] Beneficial effects: 1. This utility model adopts a three-stage design of pressure relief buffer tank, detection buffer tank and pressurization buffer tank. The pressure relief tank solves the safety risks of high pressure sampling, and the pressurization tank solves the risk of safe return. It completely liberates the electrode from extreme working conditions, extends its service life and greatly reduces maintenance costs.

[0017] 2. This invention, by incorporating a heat dissipation device and a pressure relief buffer tank, cools and depressurizes high-temperature, high-pressure materials before they come into contact with the pH electrode, ensuring that the electrode always operates in a stable environment under mild, normal pressure. This fundamentally avoids problems such as membrane aging and reference solution leakage caused by direct exposure of the electrode to the extreme environment inside the reactor, significantly extending its service life from less than 3 months for traditional online installations, and substantially reducing electrode replacement frequency and maintenance costs.

[0018] 3. This utility model changes the traditional offline sampling and analysis lag mode by using bottom tube sampling and external circulation detection. It can reflect the dynamic changes of pH in the material inside the reactor in real time. This allows operators to adjust process parameters in a timely manner, effectively avoiding problems such as reaction runaway and increased by-products caused by untimely control, and improving product quality and reaction efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the polyvinyl caprolactam pH value detection device of this utility model; Figure 2 This is a schematic diagram of the reactor structure of this utility model.

[0020] The above figures include the following reference numerals: 1. Material sampling device; 2. Second gate valve; 3. Second valve; 4. Heat dissipation device; 5. Fifth valve; 6. Third valve; 7. Fourth valve; 8. Pressure relief buffer tank; 9. First valve; 10. First control valve; 11. pH value measurement structure; 12. Detection buffer tank; 13. Second control valve; 14. Pressurized buffer tank; 15. First gate valve; 16. Third gate valve; 17. Reactor. Detailed Implementation

[0021] The specific embodiments of this utility model are described below with reference to the accompanying drawings and examples: It should be noted that the structures, proportions, sizes, etc. shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0022] Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of implementation of this utility model.

[0023] According to an embodiment of this utility model, a polyvinyl caprolactam pH value detection device is provided, such as... Figure 1The system includes a reaction vessel 17, a material sampling device 1, and a material conveying pipeline. The reaction vessel 17 has a material outlet and a material inlet. One end of the material sampling device 1 is inserted into the reaction vessel 17 through the material outlet, and the other end of the material sampling device 1 is connected to one end of the material conveying pipeline. The other end of the material conveying pipeline is connected to the material inlet. A pressure relief buffer tank 8, a detection buffer tank 12, and a pressurization buffer tank 14 are sequentially arranged on the material conveying pipeline. A pH measuring structure 11 is placed in the detection buffer tank 12. The material conveying pipeline transports the material to be tested taken from the reaction vessel 17 by the material sampling device 1 to the pressure relief buffer tank 8, the detection buffer tank 12, and the pressurization buffer tank 14 in sequence, and then returns it to the material inlet. A pressure regulating device is connected to the pressure relief buffer tank 8 to regulate the pressure inside the pressure relief buffer tank 8. This application uses a material sampling device 1, with one end inserted into the reaction vessel 17 through the material outlet. The other end of the sampling device 1 is connected to one end of the material conveying pipeline, and the other end of the material conveying pipeline is connected to the material inlet, ensuring the continuity and representativeness of the sampling process. Subsequently, the material is conveyed through the material conveying pipeline to the pressure relief buffer tank 8. This step aims to reduce the impact of the high pressure inside the reaction vessel 17 on subsequent testing and prevent damage to the pH measurement structure 11. Afterward, the material flows smoothly into the detection buffer tank 12, where the pH measurement structure 11 can accurately measure the pH value of the sample without direct exposure to the extreme environment of the reaction vessel 17, significantly extending the service life of the measurement structure. Finally, the tested material is returned to the reaction vessel 17 through the pressure boosting buffer tank 14. The pressure boosting buffer tank 14 is set to maintain the same or slightly higher pressure as the reaction vessel 17, ensuring smooth material return and preventing the intrusion of external contaminants. The entire process achieves rapid, real-time detection of the material's pH value, improving operational safety and accuracy, reducing production costs, and has significant application value for process control in industries such as fine chemicals and biopharmaceuticals. This technical solution not only simplifies the testing process but also reduces the risk of cross-contamination from material residues, providing strong support for optimizing production processes and improving product quality.

[0024] A heat dissipation device 4 is installed on the material conveying pipeline between the material sampling device 1 and the pressure relief buffer tank 8. The heat dissipation device 4 is a heat dissipation pipe, which adopts a spiral heat dissipation method. If the temperature of the material in the reactor 17 is too high, it will damage the pH measuring structure 11. To avoid damage to the pH measuring structure 11, a heat dissipation pipe is installed. During installation, the number of spiral turns of the heat dissipation pipe is adjusted according to the temperature of the material in the reactor 17.

[0025] A first valve 9 is installed on the material conveying pipeline between the heat dissipation device 4 and the pressure relief buffer tank 8 to control the material flow rate. The first valve 9 regulates the material flow rate to ensure that the material flows at the optimal speed and avoids inaccurate measurements due to excessive flow rate.

[0026] The material conveying pipeline between the material sampling device 1 and the heat dissipation device 4 is connected to a first pressurizing pipeline that supplies pressurized gas to the reactor 17. A second valve 3 is installed on this pressurizing pipeline. The first pressurizing pipeline transports gas, which can propel the material smoothly out of the reactor 17, ensuring continuous and representative sampling, especially under high pressure or high viscosity conditions. The second valve 3 provides precise control of the pressurized gas, preventing over-pressurization that could damage the equipment or cause material leakage, thus enhancing the safety and reliability of the system. By pressurizing the reactor 17 with gas, the use of mechanical pumps is reduced, lowering system complexity and energy consumption, while also preventing external contamination.

[0027] The pressure regulating device includes a vacuuming device, a second pressurizing pipeline that supplies pressurized gas to the pressure relief buffer tank 8, and an exhaust pipeline that maintains the pressure inside the pressure relief buffer tank 8 at atmospheric pressure. The pressure relief buffer tank 8 is connected to the vacuuming device via a first pipeline. A third valve 6, a fourth valve 7, and a fifth valve 5 are respectively installed on the first pipeline, the second pressurizing pipeline, and the exhaust pipeline. The pressure regulating device enables flexible control of the pressure inside the pressure relief buffer tank 8 (vacuuming, pressurizing, or maintaining atmospheric pressure), ensuring a smooth pressure transition within the tank, reducing pressure damage to the pH electrode. Precise valve control improves the system's adaptability to pressure fluctuations in the reactor 17. Maintaining a pressure balance environment is beneficial for the stable operation of the pH electrode, extending its service life, while simplifying the operation process and reducing maintenance frequency. After the pressure relief buffer tank 8 is evacuated or maintained at atmospheric pressure, a certain amount of gas (such as nitrogen) is added to the pressure relief buffer tank 8 via the second pressurizing pipeline to facilitate the evacuation of material from the pressure relief buffer tank 8.

[0028] The pressurized buffer tank 14 is connected to a third pressurized pipeline for supplying pressurized gas into the tank. A first gate valve 15 is installed on this third pressurized pipeline. The third pressurized pipeline allows adjustment of the pressure inside the pressurized buffer tank 14 to balance or slightly exceed the pressure inside the reactor 17, ensuring smooth material reflux and preventing obstruction or backflow. The first gate valve 15 provides reliable pressure control, enhancing the system's sealing and safety, and preventing gas leakage or pressure imbalance.

[0029] The pH measuring structure 11 is a pH electrode. Protected by the buffer tank, the electrode is protected from direct exposure to high temperatures, high pressures, and corrosive media, significantly extending its service life and reducing replacement costs and maintenance frequency. The pH electrode is located above the buffer tank and uses a quick-connect design. This quick-connect design facilitates rapid disassembly, cleaning, and calibration, reducing downtime and improving operational efficiency.

[0030] A first control valve 10 is installed on the material conveying pipeline between the pressure relief buffer tank 8 and the detection buffer tank 12, and a second control valve 13 is installed on the material conveying pipeline between the detection buffer tank 12 and the pressurization buffer tank 14. The first control valve 10 and the second control valve 13 allow independent control of the material flow between the buffer tanks, ensuring sufficient residence time for accurate measurement in the detection buffer tank 12 and improving data reliability. Isolation via control valves reduces pressure interference and material mixing between the tanks, preventing measurement signal drift.

[0031] like Figure 2 The material sampling device 1 is a bottom-insertion tube, and a second gate valve 2 is installed at the connection between the bottom-insertion tube and the material conveying pipeline. The bottom-insertion tube is located in the middle layer of the reactor and is fixed to the reactor wall by a tripod. It can take samples of the reaction liquid for testing at any time during stirring operation. The bottom-insertion tube takes samples from the middle layer of the reactor 17, ensuring the representativeness and uniformity of the samples, avoiding deviations in surface or bottom materials, and improving the accuracy of testing. The second gate valve 2 provides a reliable shut-off function to prevent material leakage or backflow, enhancing the sealing and safety of the system.

[0032] A third gate valve 16 is installed at the pipeline connection between the pressurized buffer tank 14 and the reactor 17. The third gate valve 16 is installed on the final pipeline returning from the pressurized buffer tank 14 to the reactor 17, serving as a reliable mechanical isolation point. When maintenance, cleaning, or component replacement of the entire pH detection circuit (including the buffer tank, pipelines, valves, etc.) is required, this third gate valve 16 can be closed to completely isolate the detection system from the high-pressure, high-temperature reactor 17. This ensures the safety of maintenance personnel and prevents material leakage from the reactor.

[0033] Taking the detection of pH of materials in polyvinyl caprolactam reactor 17 as an example, the specific working process of this invention is as follows: The device has just completed the previous cycle, and all valves are in the closed state, ready for a new round of testing.

[0034] Open the second valve 3 on the first pressurization pipeline and all valves on the material conveying pipeline. The first pressurization pipeline supplies a portion of the gas into the material conveying pipeline, ensuring all material returns to the reactor 17. Close all valves. Open the second gate valve 2, allowing the material in the reactor 17 to begin entering the bottom tube under internal pressure. After the material flows out, open the first valve 9 to control the flow rate of the material into the heat dissipation device 4 (e.g., a spiral heat dissipation tube). Here, the high-temperature material is rapidly cooled to near room temperature to protect downstream equipment and the pH electrode. If the pressure inside the reactor 17 is insufficient or the material is viscous, the second valve 3 can be briefly opened to inject a small amount of inert gas (e.g., nitrogen) into the reactor 17 through the first pressurization pipeline to assist in pushing the material out. The cooled material flows into the pressure relief buffer tank 8. At this time, the pressure inside the tank is released to atmospheric or safe pressure by operating the pressure regulating device: open the fifth valve 5 to release the high pressure inside the tank through the exhaust pipeline; or open the third valve 6 to connect the vacuum device to accelerate pressure relief and material inflow. After depressurization is complete, close valves 5 and 6. If necessary, open valve 7 to introduce a small amount of nitrogen to force the material in depressurization buffer tank 8 into detection buffer tank 12. Once the material level in depressurization buffer tank 8 is confirmed to be at a certain level, open control valve 10, allowing the material to flow into detection buffer tank 12. At this time, the pH electrode installed on the tank measures the pH value of the material in a stable and mild environment and transmits the data to the control system in real time.

[0035] After measurement, the second control valve 13 is opened, allowing the measured material to flow into the pressure buffer tank 14 by gravity. The second control valve 13 is closed, and then the first gate valve 15 is slowly opened, injecting inert gas into the pressure buffer tank 14 through the third pressurization pipeline, raising its internal pressure to approximately equal to or slightly higher than the pressure in the reactor 17. The third gate valve 16 is then slowly opened. Because the pressure in the pressure buffer tank 14 is equal to or slightly higher than that in the reactor 17, the material is smoothly pumped back into the reactor 17, completing a full detection cycle. After all the material has been returned, the third gate valve 16 and the first gate valve 15 are closed sequentially. The system returns to its initial state, ready for the next test. The entire process, through the orderly opening and closing of valves, achieves automatic sampling, cooling, depressurization, detection, and return of materials, enabling rapid, safe, and accurate real-time pH monitoring.

[0036] Many other changes and modifications can be made without departing from the concept and scope of this utility model. It should be understood that this utility model is not limited to the specific embodiments, and the scope of this utility model is defined by the appended claims.

Claims

1. A pH value detection device for polyvinyl caprolactam, characterized in that, The system includes a reaction vessel, a material sampling device, and a material conveying pipeline. The reaction vessel has a material outlet and a material inlet. One end of the sampling device is inserted into the reaction vessel through the material outlet, and the other end of the sampling device is connected to one end of the material conveying pipeline, which is connected to the other end of the material conveying pipeline. A pressure relief buffer tank, a detection buffer tank, and a pressurization buffer tank are sequentially arranged on the material conveying pipeline. A pH measuring device is placed in the detection buffer tank. The material conveying pipeline transports the material to be tested taken from the reaction vessel by the sampling device to the pressure relief buffer tank, the detection buffer tank, and the pressurization buffer tank in sequence, and then returns it to the material inlet. A pressure regulating device is connected to the pressure relief buffer tank to adjust the pressure inside the tank.

2. The polyvinyl caprolactam pH detection device according to claim 1, characterized in that, A heat dissipation device is installed on the material conveying pipeline between the sampling device and the pressure relief buffer tank.

3. The polyvinyl caprolactam pH detection device according to claim 2, characterized in that, A first valve for controlling the material flow is installed on the material conveying pipeline between the heat dissipation device and the pressure relief buffer tank.

4. The polyvinyl caprolactam pH detection device according to claim 2, characterized in that, The material conveying pipeline between the sampling device and the heat dissipation device is connected to a first pressurizing pipeline for conveying pressurized gas into the reactor, and a second valve is installed on the pressurizing pipeline.

5. The polyvinyl caprolactam pH detection device according to claim 1, characterized in that, The pressure regulating device includes a vacuum pumping device, a second pressurizing pipeline for supplying pressurized gas into the pressure relief buffer tank, and an exhaust pipeline for maintaining the pressure inside the pressure relief buffer tank at atmospheric pressure. The pressure relief buffer tank is connected to the vacuum pumping device through a first pipeline. A third valve, a fourth valve, and a fifth valve are respectively installed on the first pipeline, the second pressurizing pipeline, and the exhaust pipeline.

6. The polyvinyl caprolactam pH detection device according to claim 1, characterized in that, The pressurized buffer tank is connected to a third pressurized pipeline that supplies pressurized gas into the pressurized buffer tank, and a first gate valve is installed on the third pressurized pipeline.

7. The polyvinyl caprolactam pH detection device according to claim 1, characterized in that, The pH measurement structure is a pH electrode.

8. The polyvinyl caprolactam pH detection device according to claim 1, characterized in that, A first control valve is installed on the material conveying pipeline between the pressure relief buffer tank and the detection buffer tank, and a second control valve is installed on the material conveying pipeline between the detection flushing tank and the pressure buffer tank.

9. The polyvinyl caprolactam pH detection device according to claim 1, characterized in that, The material sampling device is a bottom-insertion tube, and a second gate valve is provided at the connection between the bottom-insertion tube and the material conveying pipeline.

10. The polyvinyl caprolactam pH detection device according to claim 1, characterized in that, A third gate valve is installed on the material conveying pipeline between the pressurized buffer tank and the material inlet.

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