Metering and dissolving device for polyacrylonitrile powder

Abstract

The application relates to a kind of polyacrylonitrile powder metering, dissolving device, belongs to the dissolving equipment technical field of polyacrylonitrile powder;Innovatively, weighing module is directly integrated below lug of double helix conical mixer, and double-loop metering system is formed with mass flow meter of conveying solvent, and through receiving total weight signal of powder of weighing module and instantaneous flow signal of flow meter of solvent, instantaneous flow and cumulative amount of powder can be calculated in real time, high-precision quantitative control to powder difficult to measure is realized, and the feeding ratio of powder and solvent is highly accurate and stable;A unique downward spraying solvent injection mode is designed: the nozzle is arranged above the powder feeding port and vertically downward spraying, so that the solvent uniformly covers the continuously moving and turbulent powder material in the form of mist, so that the instantaneous, bidirectional and three-dimensional contact between the solvent and the powder is realized, and the problems of local caking or uneven distribution of solvent are avoided, and the uniformity and dissolution efficiency of initial mixing are greatly improved.

Description

Technical Field

[0001] This utility model belongs to the technical field of polyacrylonitrile powder dissolution equipment, specifically relating to a metering and dissolution device for polyacrylonitrile powder. Background Technology

[0002] Carbon fiber is a high-strength, high-modulus, temperature-resistant, and corrosion-resistant fiber material widely used in aerospace, military, and civilian fields, making it an excellent material. The superior properties of carbon fiber are primarily determined by the precursor fiber. In the two-step precursor fiber production process, the dissolution of polyacrylonitrile powder is a crucial step, but also the most likely to introduce defects, significantly impacting the strength of the carbon fiber.

[0003] The current dissolving process involves a long conveying and weighing process, and involves many pieces of equipment, which is not simple enough. It is necessary to centralize some functions and reduce the conveying and weighing process and equipment.

[0004] Polyacrylonitrile powder tends to clump when dissolved with DMAc or DMSO. Once clumped, this powder becomes very difficult to dissolve and can only be removed by filtration, which undoubtedly increases the pressure on the filter. Some clumps even pass through the filter and into the spinning process, causing filament breakage and seriously affecting the stability of the precursor fiber production. Summary of the Invention

[0005] The present invention mainly addresses the technical problems existing in the prior art by providing a metering and dissolving device for polyacrylonitrile powder.

[0006] The above-mentioned technical problems of this utility model are mainly solved by the following technical solution: a metering and dissolving device for polyacrylonitrile powder, comprising a silo, a pneumatic diaphragm pump, a double helical cone mixer, a liquid storage tank, a centrifugal pump, a flow meter, a flow regulating valve, a pneumatic switching valve, a weighing module, and a control system panel. The double helical cone mixer has a powder inlet and a solvent inlet at its top center, and a nozzle at the end of the solvent inlet. The pneumatic diaphragm pump is located between the silo and the double helical cone mixer, and they are connected by a pipeline. The outlet of the pipeline is connected to the powder inlet of the double helical cone mixer. A solenoid valve is installed on the air source pipeline of the pneumatic diaphragm pump. The silo and the double helical cone mixer are both made of 304 or 316L stainless steel. Both the double helical cone mixer and the liquid storage tank are equipped with jackets, and the jackets are made of 316L stainless steel. The liquid storage tank is connected to the double helical cone mixer by a pipeline, and the outlet of the pipeline is connected to the solvent inlet of the double helical cone mixer.

[0007] Preferably, the flow meter, flow regulating valve, and pneumatic switching valve are installed on the pipeline between the liquid storage tank and the double spiral cone mixer; the centrifugal pump is located on the pipeline between the pneumatic switching valve and the liquid storage tank; the nozzle is located inside the double spiral cone mixer, pointing vertically downwards, and its installation height is higher than the powder inlet; the double spiral cone mixer includes four lugs, and the weighing module is located on the lower side of the four lugs.

[0008] Preferably, the pneumatic diaphragm pump is made of 304 or 316L stainless steel, and the solenoid valve on its air source pipeline is connected to the control system panel.

[0009] Preferably, the flow meter is a mass flow meter, and it is connected to the control system panel along with the flow regulating valve and the pneumatic switching valve.

[0010] Preferably, the jacket between the double helical cone mixer and the liquid storage tank is equipped with a hot water circulation system, which includes a circulation pipeline valve.

[0011] The beneficial effects of this utility model are:

[0012] The weighing module is innovatively integrated directly into the lower part of the support lug of the double spiral cone mixer, forming a dual-loop metering system with the mass flow meter for conveying solvent. The control panel receives the total powder weight signal from the weighing module and the instantaneous solvent flow signal from the flow meter, performs cross-calculation and compensation, and can calculate the instantaneous flow rate and cumulative amount of powder in real time. This achieves high-precision, closed-loop quantitative control of powders that are difficult to measure, ensuring a highly accurate and stable powder-to-solvent feeding ratio.

[0013] A unique downward spraying solvent injection method was designed: the nozzle is set above the powder inlet and sprays vertically downward, so that the solvent evenly covers the constantly moving and churning powder material in the form of a mist, realizing instantaneous, bidirectional, and three-dimensional contact between the solvent and the powder, avoiding the problems of local agglomeration or uneven solvent distribution, greatly improving the uniformity of initial mixing and dissolution efficiency, and optimizing the mixing process from a structural perspective. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] In the diagram: 1. Silo; 2. Pneumatic diaphragm pump; 3. Solenoid valve; 4. Double spiral cone mixer; 5. Nozzle; 6. Weighing module; 7. Liquid storage tank; 8. Centrifugal pump; 9. Pneumatic switch valve; 10. Flow meter; 11. Flow regulating valve; 13. Control system panel; 14. Circulation pipeline valve; 15. Solvent inlet; 16. Jacket; 17. Support lug; 18. Hot water circulation system; 19. Powder inlet. Detailed Implementation

[0016] The technical solution of this utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0017] Example: A metering and dissolving device for polyacrylonitrile powder, such as... Figure 1 As shown, the system includes a hopper 1, a pneumatic diaphragm pump 2, a double helical cone mixer 4, a liquid storage tank 7, a centrifugal pump 8, a flow meter 10, a flow regulating valve 11, a pneumatic switching valve 9, a weighing module 6, and a control system panel 13. The double helical cone mixer 4 has a powder inlet 19 and a solvent inlet 15 at its top center, with a nozzle 5 at the end of the solvent inlet 15. The pneumatic diaphragm pump 2 is located between the hopper 1 and the double helical cone mixer, connected by a pipeline. The pipeline outlet is connected to the double helical cone mixer. The powder inlet 19 of the mixer 4 is provided with a solenoid valve 3 on the air source pipeline of the pneumatic diaphragm pump 2. The material of the hopper 1 and the double helical cone mixer 4 is either 304 or 316L stainless steel. The double helical cone mixer 4 and the liquid storage tank 7 are both provided with jackets 16, and the material of the jackets 16 is 316L stainless steel. The liquid storage tank and the double helical cone mixer are connected by a pipeline, and the outlet of the pipeline is connected to the solvent inlet 15 of the double helical cone mixer 4.

[0018] The flow meter 10, flow regulating valve 11, and pneumatic switch valve 9 are installed on the pipeline between the liquid storage tank and the double spiral cone mixer. The centrifugal pump 8 is located on the pipeline between the pneumatic switch valve 9 and the liquid storage tank 7. The nozzle 5 is located inside the double spiral cone mixer 4, pointing vertically downwards, and its installation height is higher than the powder inlet. The double spiral cone mixer 4 includes four lugs 17, and the weighing module 6 is located on the lower side of the four lugs 17.

[0019] The pneumatic diaphragm pump 2 is made of 304 or 316L stainless steel, and the solenoid valve 3 on its air source pipeline is connected to the control system panel 13.

[0020] The flow meter 10 is a mass flow meter 10, and it, along with the flow regulating valve 11 and the pneumatic switching valve 9, are all connected to the control system panel 13.

[0021] A hot water circulation system 18 is provided in the jacket 16 between the double helix cone mixer 4 and the liquid storage tank 7. The hot water circulation system 18 includes a circulation pipeline valve 14. The control system panel 13 issues a command to open the solenoid valve 3 on the air source pipeline of the pneumatic diaphragm pump 2. Compressed air drives the pneumatic diaphragm pump 2 to work, pumping the polyacrylonitrile powder in the silo 1 into the powder inlet 19 of the double helix cone mixer 4 through the pipeline.

[0022] The weighing module 6 monitors the total weight of the double-helix cone mixer 4 (including the internal materials) in real time and transmits the data to the control system panel 13. Based on the real-time weight increment, the control system panel 13 calculates the instantaneous feed rate and cumulative feed amount of the powder. This weight-based metering method overcomes the industry problem of inaccurate measurement by the direct flow meter 10 for powder.

[0023] Centrifugal pump 8 pumps the solvent out of liquid storage tank 7, which flows through mass flow meter 10 (measuring instantaneous flow), regulating valve (precisely regulating flow) and pneumatic switch valve 9 (responsible for starting and stopping);

[0024] The control system panel 13 receives the flow signal from the flow meter 10 and compares it with the calculated instantaneous flow rate of the powder. The control system panel 13 dynamically adjusts the opening of the regulating valve to make the solvent flow rate closely follow the change in the powder flow rate, ensuring that the two are always added to the double helical cone mixer 4 in strict accordance with the preset ratio, forming a closed-loop control.

[0025] The precisely metered solvent reaches the nozzle 5 through the pipeline and is sprayed into the double helical cone mixer 4 in a vertically downward mist. Since the height of the nozzle 5 is higher than the powder inlet, the solvent can evenly cover the powder that is being continuously turned up and thrown by the double helical blades and is in motion.

[0026] This combination of "spraying" and "mechanical turning" creates a huge contact area, achieving instantaneous and uniform mixing of solvent and powder. It effectively prevents powder from clumping when it comes into contact with liquid, greatly improving the initial dispersion effect and subsequent dissolution efficiency. The powder and solvent outlets are at a 90° angle to the cantilever of the double spiral, and each end is connected to a downward-facing elbow. Each has a rotary joint that can rotate with the cantilever. The solvent inlet 15 is connected to a nozzle 5 at its end, which is higher than the powder inlet 19. The top flange of the double spiral conical mixer 4 is connected to a cloth bag to expel internal gas.

[0027] Liquid storage tank 7 is continuously supplied with 30°C water in jacket 16. Centrifugal pump 8 is turned on, and circulation pipeline valve 14 is fully opened to maintain the tank temperature. Double spiral cone mixer 4 is supplied with 30°C water in jacket 16 for 30 minutes to preheat it. Then, on the control system's operating screen, the ratio of powder to solvent is entered as 1:4. The total powder amount is set to 400 kg, and the total solvent DMAc amount is set to 1600 kg. At this time, the stirring motor of double spiral cone mixer 4 is turned on, and the total amount data recorded by weighing module 6 is reset to "zero". Then, the start button on the operating screen is clicked, and the system starts.

[0028] Solenoid valve 3 and pneumatic switch valve 9 start automatically and simultaneously, the diaphragm pump begins feeding, and the solvent also begins feeding. At this time, the flow rate of powder and solvent will be displayed on the operation panel. The solvent flow rate is automatically adjusted by the regulating valve to make the ratio of powder to solvent flow rate 1:4. When the actual total amount of powder and solvent reaches the set total amount, feeding will stop immediately, solenoid valve 3 will close, the diaphragm pump will stop feeding, pneumatic switch valve 9 will close, and solvent feeding will stop.

[0029] After the motor of the double helical cone mixer 4 continued to run for 2-3 hours, a sample was taken for testing, and a polyacrylonitrile solution of 20±0.05% was obtained.

[0030] Example 2

[0031] like Figure 1 As shown, in this embodiment of the invention, the liquid storage tank 7 is continuously supplied with water at 20°C through the jacket 16, the centrifugal pump 8 is turned on, and the circulation pipeline valve 14 is fully opened to maintain the temperature inside the tank. The double helical cone mixer 4 is supplied with water at 20°C through the jacket 16 for 30 minutes to preheat the double helical cone mixer 4. Then, the ratio of powder to solvent (9:41) is input on the control system's operating screen, the total powder amount is set to 360 kg, and the total amount of solvent DMAc is set to 1640 kg. At this time, the stirring motor of the double helical cone mixer 4 is turned on, and the total amount data recorded by the weighing module 6 is reset to "zero". Then, the start button on the operating screen is clicked, and the system starts.

[0032] Solenoid valve 3 and pneumatic switch valve 9 start automatically and simultaneously. The diaphragm pump starts feeding, and the solvent also starts feeding. At this time, the flow rate of powder and solvent will be displayed on the operation panel. The solvent flow rate is automatically adjusted by the regulating valve to make the ratio of powder to solvent flow rate 9:41. When the actual total amount of powder and solvent reaches the set total amount, feeding can be stopped. Solenoid valve 3 closes, which means the diaphragm pump stops feeding. Pneumatic switch valve 9 closes, which means the solvent stops feeding.

[0033] After the motor of the double helical cone mixer 4 continued to run for 2-3 hours, a sample was taken for testing, and a polyacrylonitrile solution of 18±0.05% was obtained.

[0034] Finally, it should be noted that the above embodiments are merely representative examples of this utility model. Obviously, this utility model is not limited to the above embodiments and can have many variations. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model should be considered to fall within the protection scope of this utility model.

Claims

1. A metering and dissolving device for polyacrylonitrile powder, comprising: The system comprises a silo (1), a pneumatic diaphragm pump (2), a double spiral cone mixer (4), a liquid storage tank (7), a centrifugal pump (8), a flow meter (10), a flow regulating valve (11), a pneumatic switch valve (9), a weighing module (6), and a control system panel (13). The double spiral cone mixer (4) has a powder inlet (19) and a solvent inlet (15) at its top center, with a nozzle (5) at the end of the solvent inlet (15). The pneumatic diaphragm pump (2) is located between the silo (1) and the double spiral cone mixer, connected by a pipe, with the pipe outlet connected to… The powder inlet (19) of the double spiral cone mixer (4) is connected to the air source pipeline of the pneumatic diaphragm pump (2). The material of the silo (1) and the double spiral cone mixer (4) is either 304 or 316L stainless steel. The double spiral cone mixer (4) and the liquid storage tank (7) are both equipped with jackets (16). The material of the jackets (16) is 316L stainless steel. The liquid storage tank (7) and the double spiral cone mixer are connected by a pipeline. The outlet of the pipeline is connected to the solvent inlet (15) of the double spiral cone mixer (4).

2. The metering and dissolving device for polyacrylonitrile powder according to claim 1, characterized in that: The flow meter (10), flow regulating valve (11) and pneumatic switch valve (9) are installed on the pipeline between the liquid storage tank (7) and the double spiral cone mixer. The centrifugal pump (8) is located on the pipeline between the pneumatic switch valve (9) and the liquid storage tank (7). The nozzle (5) is located inside the double spiral cone mixer (4), with its direction vertically downward and its installation height higher than the powder inlet. The double spiral cone mixer (4) includes four lugs (17), and the weighing module (6) is located on the lower side of the four lugs (17).

3. The metering and dissolving device for polyacrylonitrile powder according to claim 1, characterized in that: The pneumatic diaphragm pump (2) is made of 304 or 316L stainless steel, and the solenoid valve (3) on its air source pipeline is connected to the control system panel (13).

4. The metering and dissolving device for polyacrylonitrile powder according to claim 1, characterized in that: The flow meter (10) is a mass flow meter (10), and it, along with the flow regulating valve (11) and the pneumatic switching valve (9), are connected to the control system panel (13).

5. The metering and dissolving device for polyacrylonitrile powder according to claim 1, characterized in that: A hot water circulation system (18) is provided in the jacket (16) between the double helical cone mixer (4) and the liquid storage tank (7), and the hot water circulation system (18) includes a circulation pipeline valve (14).

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