Refining and filtering system for polyacrylonitrile spinning solution

Abstract

The invention discloses a refining and filtering system for a polyacrylonitrile spinning solution, and belongs to the technical field of spinning solution filtering in the carbon fiber industry. The interior of the pipeline is polished to be Ra smaller than 0.4, and hot water or steam is introduced into the jacket for heat preservation; the static mixer is provided with a heat preservation jacket and is responsible for mixing and heating the stock solution; the filter cloth type or candlewick type filter is responsible for coarse filtration of the stock solution; the candlewick type or laminated filter is responsible for fine filtration of the stock solution; the pressure transmitter is responsible for detecting the pressure of the stock solution in the pipeline and the pressure difference before and after the filter; the temperature transmitter is responsible for monitoring the temperature of the stock solution; and the regulating valve is responsible for regulating the flow of the jacket heat source so as to regulate the temperature of the stock solution. The filtering mode of the polyacrylonitrile spinning solution can be optimized, impurities such as small gel in the spinning solution can be reduced to pass through the filter, high purification of the spinning solution is facilitated, and preparation of high-performance carbon fibers is greatly promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of spinning solution filtration in the carbon fiber industry, and in particular relates to a refining filtration system for polyacrylonitrile spinning solution. Background Art

[0002] During the polymerization process of the spinning solution, a small amount of gel is produced. These gel particles are large and small and elastic. They are easily affected by pressure and temperature and pass through the filter, affecting the high purification of the solution.

[0003] The presence of gel in the stock solution is an important reason for the generation of hairy and broken yarns during the spinning process. Therefore, the spinning stock solution needs to be filtered before spinning. The current filtration system only solves the problem of small gels by updating the filtration equipment, but does not pay enough attention to temperature and pressure, resulting in some small gels passing through the filter due to pressure or temperature, thus causing hairy and broken yarns.

[0004] The presence of gel also affects the performance of subsequent carbon fibers. Removing impurities such as gel in the spinning solution is also an important prerequisite for preparing high-performance PAN-based carbon fibers. Summary of the invention

[0005] The present invention mainly solves the technical problems existing in the above-mentioned prior art and provides a refining and filtering system for polyacrylonitrile spinning stock solution.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions: a refining filtration system for polyacrylonitrile spinning stock solution, comprising a static mixer 1, a static mixer 2 and a connecting pipe, a filter component 1 is arranged between the static mixer 1 and the static mixer 2, and a filter component 1 and a filter component 2 are arranged on both sides of the static mixer 2 respectively, the connecting pipe is used to connect the static mixer 1, the filter component 1, the static mixer 2 and the filter component 2, a temperature sensing component and a pressure sensing component are arranged on the connecting pipe, a regulating valve 1 is arranged on the static mixer 1, a regulating valve 2 is arranged on the static mixer 2, the static mixer 1, the static mixer 2, the filter component 1, the filter component 2 and the connecting pipe are all provided with an insulation jacket, and a heat source is arranged inside the insulation jacket.

[0007] Preferably, the filter assembly 1 includes filter 1 and filter 2, the liquid inlet ends of filter 1 and filter 2 are connected to static mixer 1 through a connecting pipe, and the liquid outlet ends of filter 1 and filter 2 are connected to static mixer 2 through a connecting pipe.

[0008] Preferably, the filter assembly 2 includes a filter 3 and a filter 4, and the liquid inlet ends of the filter 3 and the filter 4 are both connected to the static mixer 2 through a connecting pipe.

[0009] Preferably, the temperature sensing assembly includes temperature sensor 1, temperature sensor 2, temperature sensor 3 and temperature sensor 4, temperature sensor 1 is arranged on the connecting tube and close to the liquid inlet end of the filter 1, temperature sensor 2 is arranged on the connecting tube and close to the liquid inlet end of the filter 2, temperature sensor 3 is arranged on the connecting tube and close to the liquid inlet end of the filter 3, and temperature sensor 4 is arranged on the connecting tube and close to the liquid inlet end of the filter 4.

[0010] Preferably, the pressure sensing component includes pressure sensor 1, pressure sensor 2, pressure sensor 3 and pressure sensor 4, pressure sensor 1 and pressure sensor 2 are respectively located at the two ends of filter component 1, and pressure sensor 3 and pressure sensor 4 are respectively located at the two ends of filter component 2.

[0011] Preferably, the connecting pipe, filter assembly 1 and filter assembly 2 are all made of 304 or 316L stainless steel, the internal polishing accuracy of the connecting pipe is Ra<0.4μm, and the internal polishing accuracy of the filter assembly 1 and filter assembly 2 is Ra≤0.4μm.

[0012] Preferably, the heat source in the thermal insulation jacket is hot water or steam.

[0013] Preferably, the temperature of the hot water in the insulation jackets of the static mixer 1 and the static mixer 2 is between 50° C. and 90° C., and the steam pressure is between 0.1 MPa and 0.3 MPa.

[0014] Preferably, the front-to-rear pressure difference of the filter assembly 1 and the filter assembly 2 is 0.05 MPa to 0.3 MPa.

[0015] The present invention has the beneficial effects:

[0016] Compared with the prior art, the present invention reduces impurities forced through the filter due to pressure and improves the purity of the raw liquid by limiting the pressure range of the raw liquid before filtration; the raw liquid passes through a static mixer before filtration, which can make the temperature of the raw liquid in the pipeline more uniform and prevent gel aggregation, so that all gels and the raw liquid can be uniformly sent to the filter, and all filter elements operate in the same state, preventing gel from aggregating in individual filter elements, thereby allowing part of the gel to pass through the filter; the raw liquid temperature at the inlet of the filter element can be adjusted, and different temperatures can be selected before filters with different filtration accuracies to achieve the best filtration effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the present invention;

[0018] Figure 2 It is a schematic diagram of the process of the present invention.

[0019] In the figure: 1. static mixer 1; 2. pressure sensor 1; 3. temperature sensor 1; 4. regulating valve 1; 5. filter 1; 6. filter 2; 7. temperature sensor 2; 8. pressure sensor 2; 9. static mixer 2; 10. pressure sensor 3; 11. temperature sensor 3; 12. regulating valve 2; 13. filter 3; 14. filter 4; 15. temperature sensor 4; 16. pressure sensor 4. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0021] The following are examples and the attached Figure 1-Figure 2 As shown in the structure, the technical solution of the present invention is further specifically described. The viscosity of the stock solution in the following embodiment is 50,000 cP to 100,000 cP, and the PLC described in the embodiment is a PLC controller external to the system of the present invention.

[0022] A refined filtration system for polyacrylonitrile spinning stock solution comprises a static mixer 1, a static mixer 2 9, a filter assembly 1 and a filter assembly 2, wherein the static mixer 1, the static mixer 2 9, the filter assembly 1 and the filter assembly 2 are connected through a connecting pipe; the filter assembly 1 and the filter assembly 2 are respectively located at the two ends of the static mixer 2 9, and the static mixer 1, the static mixer 2 9, the filter assembly 1, the filter assembly 2 and the connecting pipe are all provided with a thermal insulation jacket, and the heat source in the thermal insulation jacket is hot water or steam, the hot water temperature is 50°C to 90°C, and the steam pressure is 0.1MPa to 0.3MPa; a temperature sensing assembly and a pressure sensing assembly are provided on the connecting pipe, and a regulating valve 1 4 and a regulating valve 2 12 are respectively provided on the static mixer 1 and the static mixer 2 9; the connecting pipe, the filter assembly 1 and the filter assembly 2 are all made of 304 or 316L stainless steel, the internal polishing accuracy of the connecting pipe is Ra<0.4μm, and the internal polishing accuracy of the filter assembly 1 and the filter assembly 2 is Ra≤0.4μm.

[0023] The filter assembly 1 includes a filter 1 5 and a filter 2 6, the liquid inlet ends of the filter 1 5 and the filter 2 6 are connected to the static mixer 1 through a connecting pipe, and the liquid outlet ends of the filter 1 5 and the filter 2 6 are connected to the static mixer 2 9 through a connecting pipe. The filter assembly 2 includes a filter 3 13 and a filter 4 14, and the liquid inlet ends of the filter 3 13 and the filter 4 14 are connected to the static mixer 2 9 through a connecting pipe.

[0024] The temperature sensing assembly includes temperature sensor 1 3, temperature sensor 2 7, temperature sensor 3 11 and temperature sensor 4 15. Temperature sensor 1 3 is arranged on the connecting pipe and close to the liquid inlet end of the filter 1 5, temperature sensor 2 7 is arranged on the connecting pipe and close to the liquid inlet end of the filter 2 6, temperature sensor 3 11 is arranged on the connecting pipe and close to the liquid inlet end of the filter 3 13, and temperature sensor 4 15 is arranged on the connecting pipe and close to the liquid inlet end of the filter 4 14.

[0025] The pressure sensing component includes pressure sensor 1 2, pressure sensor 2 8, pressure sensor 3 10 and pressure sensor 4 16. Pressure sensor 1 2 and pressure sensor 2 8 are respectively located at the two ends of the filter component 1, and pressure sensor 3 10 and pressure sensor 4 16 are respectively located at the two ends of the filter component 2.

[0026] The following is a detailed description of the working process and principle of a polyacrylonitrile spinning solution refining and filtration system according to the present invention through multiple embodiments.

[0027] Example 1: Please refer to Figure 1 and Figure 2 , a refined filtration system for polyacrylonitrile spinning stock solution, the stock solution from the upstream side, with a viscosity of 70,000 cP, is transported to a static mixer-1, the jacket of the static mixer-1 is heated with water at 70°C, the jacket outlet is connected to a regulating valve-4, the temperature sensor-3 is set at 50°C, and is interlocked with the regulating valve-4 through PLC control, the regulating valve-4 adjusts the valve opening in real time to maintain the temperature of the temperature sensor-3 stable at 50°C, the filtration accuracy of the filter-5 is 5μm, the pressure sensor-2 and the pressure sensor-28 display the pressure value in real time, and the difference PDI1 between the pressure sensor-2 and the pressure sensor-28 is calculated and displayed through the PLC. The pressure sensor-2 does not exceed 0.8MPa, and the PDI1 does not exceed 0.3MPa.

[0028] When the pressure or differential pressure exceeds the set value, the standby filter 26 should be opened, and the two filters filter at the same time. After the standby filter 26 is stable, the filter 15 is cut off in time, and the temperature sensor 13 is switched to the temperature sensor 27 and the regulating valve 14 is interlocked for control.

[0029] The jacket of static mixer 2 9 is heated to 80℃, the outlet of the jacket is connected to regulating valve 2 12, the temperature sensor 3 11 is set to 55℃, and is interlocked with regulating valve 2 12 through PLC control. Regulating valve 2 12 adjusts the valve opening in real time to maintain the temperature of temperature sensor 3 11 stable at 55℃, the filtration accuracy of filter 3 13 is 2μm, pressure sensor 3 10 and pressure sensor 4 16 display the pressure value on the display in real time, and the difference PDI2 between pressure sensor 3 10 and pressure sensor 4 16 is calculated and displayed through PLC. Pressure sensor 3 10 does not exceed 0.8MPa, and PDI2 does not exceed 0.3MPa.

[0030] When the pressure or pressure difference exceeds the set value, the backup filter four 14 should be opened, and the two filters should filter at the same time. After the filter four 14 is stable, the filter three 13 is cut off in time, and the temperature sensor three 11 is switched to the temperature sensor four 15 and the regulating valve two 12 are interlocked for control.

[0031] Example 2: Reference Figure 1 and Figure 2 , a polyacrylonitrile spinning stock solution refining and filtering system as described in Example 1 is used, the stock solution from the upstream side has a viscosity of 50,000 cP and is transported to the static mixer-1, the jacket of the static mixer-1 is heated to 60°C, the jacket outlet is connected to the regulating valve-4, the temperature sensor-3 is set to 45°C, and is interlocked with the regulating valve-4 through PLC control, the regulating valve-4 adjusts the valve opening in real time to maintain the temperature of the temperature sensor-3 stable at 45°C, the filtration accuracy of the filter-5 is 5μm, the pressure sensor-2 and the pressure sensor-28 display the pressure value in real time, and the difference PDI1 between the pressure sensor-2 and the pressure sensor-28 is calculated and displayed through the PLC. The pressure sensor-2 does not exceed 0.8MPa, and the PDI1 does not exceed 0.3MPa.

[0032] When the pressure or differential pressure exceeds the set value, the standby filter 26 should be opened, and the two filters filter at the same time. After the standby filter 26 is stable, the filter 15 is cut off in time, and the temperature sensor 13 is switched to the temperature sensor 27 and the regulating valve 14 is interlocked for control.

[0033] The jacket of static mixer 2 9 is connected to hot water at 70℃, the outlet of the jacket is connected to regulating valve 2 12, the temperature sensor 3 11 is set to 50℃, and is interlocked with regulating valve 2 12 through PLC control. Regulating valve 2 12 adjusts the valve opening in real time to maintain the temperature of temperature sensor 3 11 stable at 50℃, the filtration accuracy of filter 3 13 is 2μm, pressure sensor 3 10 and pressure sensor 4 16 display the pressure value on the display in real time, and the difference PDI2 between pressure sensor 3 10 and pressure sensor 4 16 is calculated and displayed through PLC. Pressure sensor 3 10 cannot exceed 0.8MPa, and PDI2 cannot exceed 0.3MPa.

[0034] When the pressure or pressure difference exceeds the set value, the spare filter four 14 should be opened, and the two filters filter at the same time. After the spare filter four 14 is stable, the filter three 13 is cut off in time, and the temperature sensor three 11 is switched to the temperature sensor four 15 and the regulating valve two 12 are interlocked for control.

[0035] Example 3: Reference Figure 1 and Figure 2 , a polyacrylonitrile spinning stock solution refining and filtering system as described in Example 1 is used, the stock solution from the upstream side has a viscosity of 100,000 cP and is transported to the static mixer-1, the jacket of the static mixer-1 passes 0.2MPa steam, the jacket outlet is connected to the regulating valve-4, the temperature sensor-3 is set to 80°C, and is interlocked with the regulating valve-4 through PLC control, the regulating valve-4 adjusts the valve opening in real time to maintain the temperature of the temperature sensor-3 stable at 80°C, the filtration accuracy of the filter-5 is 5μm, the pressure sensor-2 and the pressure sensor-28 display the pressure value in real time, and the difference PDI1 between the pressure sensor-2 and the pressure sensor-28 is calculated and displayed through the PLC. The pressure sensor-2 cannot exceed 0.8MPa, and the PDI1 cannot exceed 0.3MPa.

[0036] When the pressure or differential pressure exceeds the set value, the standby filter 26 should be opened, and the two filters filter at the same time. After the standby filter 26 is stable, the filter 15 is cut off in time, and the temperature sensor 13 is switched to the temperature sensor 27 and the regulating valve 14 is interlocked for control.

[0037] The jacket of static mixer 2 9 is passed with steam at 0.2MPa, the jacket outlet is connected to regulating valve 2 12, the temperature sensor 3 11 is set at 80℃, and is interlocked with regulating valve 2 12 through PLC control. Regulating valve 2 12 adjusts the valve opening in real time to maintain the temperature of temperature sensor 3 11 stable at 80℃, the filtration accuracy of filter 3 13 is 2μm, pressure sensor 3 10 and pressure sensor 4 16 display the pressure value on the display in real time, and the difference PDI2 between pressure sensor 3 10 and pressure sensor 4 16 is calculated and displayed through PLC. Pressure sensor 3 10 does not exceed 0.8MPa, and PDI2 does not exceed 0.3MPa.

[0038] When the pressure or differential pressure exceeds the set value, the spare filter four 14 should be opened, and the two filters should filter at the same time. After the spare filter four 14 is stable, the filter three 13 should be cut off in time, and the temperature sensor three 11 should be switched to the temperature sensor four 15 and the regulating valve two 12 for interlocking control. Finally, it should be pointed out that the above embodiments are only more representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments, and there can be many variations. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention should be considered to fall within the protection scope of the present invention.

Claims

1. A refining and filtering system for polyacrylonitrile spinning solution, characterized in that: The invention comprises a static mixer 1 (1), a static mixer 2 (9) and a connecting pipe, wherein a filter assembly 1 is arranged between the static mixer 1 (1) and the static mixer 2 (9), and filter assembly 1 and filter assembly 2 are arranged on both sides of the static mixer 2 (9), respectively, and the connecting pipe is used to connect the static mixer 1 (1), the filter assembly 1, the static mixer 2 (9) and the filter assembly 2, and the connecting pipe is provided with a temperature sensing assembly and a pressure sensing assembly, the static mixer 1 (1) is provided with a regulating valve 1 (4), the static mixer 2 (9) is provided with a regulating valve 2 (12), and the static mixer 1 (1), the static mixer 2 (9), the filter assembly 1, the filter assembly 2 and the connecting pipe are all provided with a heat insulation jacket, and a heat source is arranged in the heat insulation jacket.

2. A polyacrylonitrile spinning solution refining and filtration system according to claim 1, characterized in that: The filter assembly 1 comprises a filter 1 (5) and a filter 2 (6), wherein the liquid inlet ends of the filter 1 (5) and the filter 2 (6) are both connected to the static mixer 1 (1) through a connecting pipe, and the liquid outlet ends of the filter 1 (5) and the filter 2 (6) are both connected to the static mixer 2 (9) through a connecting pipe.

3. A refining and filtering system for polyacrylonitrile spinning solution according to claim 2, characterized in that: The filter assembly 2 comprises a filter 3 (13) and a filter 4 (14), and the liquid inlet ends of the filter 3 (13) and the filter 4 (14) are both connected to the static mixer 2 (9) through a connecting pipe.

4. A polyacrylonitrile spinning solution refining and filtering system according to claim 3, characterized in that: The temperature sensing assembly comprises a temperature sensor 1 (3), a temperature sensor 2 (7), a temperature sensor 3 (11) and a temperature sensor 4 (15), wherein the temperature sensor 1 (3) is arranged on the connecting pipe and close to the liquid inlet end of the filter 1 (5), the temperature sensor 2 (7) is arranged on the connecting pipe and close to the liquid inlet end of the filter 2 (6), the temperature sensor 3 (11) is arranged on the connecting pipe and close to the liquid inlet end of the filter 3 (13), and the temperature sensor 4 (15) is arranged on the connecting pipe and close to the liquid inlet end of the filter 4 (14).

5. The system for refining and filtering polyacrylonitrile spinning solution according to claim 1, characterized in that: The pressure sensing component comprises pressure sensor one (2), pressure sensor two (8), pressure sensor three (10) and pressure sensor four (16). Pressure sensor one (2) and pressure sensor two (8) are respectively located at two ends of filter component one, and pressure sensor three (10) and pressure sensor four (16) are respectively located at two ends of filter component two.

6. The system for refining and filtering polyacrylonitrile spinning solution according to claim 1, characterized in that: The connecting pipe, filter assembly 1 and filter assembly 2 are all made of 304 or 316L stainless steel. The internal polishing accuracy of the connecting pipe is Ra<0.4μm, and the internal polishing accuracy of the filter assembly 1 and filter assembly 2 is Ra≤0.4μm.

7. The system for refining and filtering polyacrylonitrile spinning solution according to claim 1, characterized in that: The heat source in the thermal insulation jacket is hot water or steam.

8. The system for refining and filtering polyacrylonitrile spinning solution according to claim 7, characterized in that: The temperature of the hot water in the heat-insulating jackets of the static mixer 1 (1) and the static mixer 2 (9) is between 50°C and 90°C, and the steam pressure is between 0.1MPa and 0.3MPa.

9. The system for refining and filtering polyacrylonitrile spinning solution according to claim 1, characterized in that: The front and rear pressure differences of the filter assembly 1 and the filter assembly 2 are both 0.05MPa to 0.3MPa.

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