Production system capable of accurately regulating and controlling molecular weight and distribution of carbon fiber stock solution

Abstract

A production system capable of accurately regulating and controlling molecular weight and distribution of a carbon fiber stock solution comprises three preparation tanks and is characterized in that the output end of each preparation tank is correspondingly connected with an independent feeding tank, and a pipeline of the output end of each feeding tank is connected with a first feeding pump; belongs to the technical field of carbon fiber production equipment. The target molecular weight is obtained by changing the feeding amount and reaction conditions, controllability and spinnability are improved, and production of a target product is facilitated. Meanwhile, the solvent recovery system reduces material consumption and reduces the production cost of raw materials, and the RTO waste gas treatment system reduces environmental pollution and meets the requirement of green production. And the production stability and repeatability are improved through automatic control. In addition, use of a soluble metal catalyst is not involved, metal ion residues in a polymerization product are avoided, and the product has more advantages in the application fields of high-performance fibers, biomedical materials and electric devices.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber production equipment, and specifically relates to a production system capable of accurately regulating the molecular weight and distribution of carbon fiber stock solution. Background Art

[0002] Carbon fiber is a fibrous graphite material with a carbon content of more than 90% and high strength and high modulus. The quality of the polymer solution (molecular weight and its distribution) directly determines the quality of the raw fiber. The current mainstream process uses DMSO as solvent, acrylonitrile and its comonomers as raw materials, and AIBN as an initiator for intermittent preparation. As the reaction time goes by, the viscosity of the system gradually increases, resulting in the strengthening of the side reaction caused by chain transfer, which greatly reduces the molecular weight and distribution of the polymer solution, which will greatly affect the uniformity of the polymer solution and significantly reduce the mechanical properties of the material.

[0003] The present invention uses controlled living free radical polymerization (RDRP) technology to accurately control the molecular weight and molecular weight distribution of the polymer, and customize the molecular weight and distribution of the required polymer solution to meet the needs of products with different mechanical properties. Summary of the invention

[0004] The present invention mainly solves the technical problems existing in the above-mentioned prior art and provides a production system which can accurately control the molecular weight and distribution of carbon fiber stock solution.

[0005] The above technical problems of the present invention are mainly solved by the following technical solutions: a production system that can accurately control the molecular weight and distribution of carbon fiber stock solution, including three preparation tanks, characterized in that: a separate feed tank is connected to the output end of each preparation tank, and a first feed pump is connected to the pipeline at the output end of each feed tank, and a polymerization kettle is connected to the pipelines at the output ends of the three first feed pumps, a capping agent storage tank is connected to one side of the polymerization kettle, a first polymerization kettle material storage tank is connected to the pipeline at the output end of the polymerization kettle, a polymer mixer is connected to the pipeline at the output end of the first polymerization kettle material storage tank, a polymer discharge pump is connected to the pipeline between the first polymerization kettle material storage tank and the polymer mixer, a stripping tower is connected to the pipeline at the output end of the polymer mixer, a degassing tower is connected to the pipeline at the output end of the stripping tower, and the stripping tower and the degassing tower are connected to the pipeline at the output end of the stripping tower. A degassing tower discharge pump is connected to the pipeline between the degassing tower, a degassing discharge mixer is connected to the pipeline at the output end of the degassing tower, a first degassing tower discharge pump is connected to the pipeline between the degassing tower and the degassing discharge mixer, a second polymerization kettle material storage tank is connected to the pipeline at the output end of the degassing discharge mixer, a second degassing tower discharge pump is connected to the pipeline between the degassing discharge mixer and the second polymerization kettle material storage tank, a despinning polymer discharge pump is connected to the pipeline at the output end of the second polymerization kettle material storage tank, the pipeline at the output end of the despinning polymer discharge pump is connected to the despinning unit, a group of DMSO feed pipes are arranged on the top of the polymerization kettle, the output end of the DMSO feed pipe main pipeline is connected to a first cooler, a tail gas absorption tower is arranged on the pipeline at the output end of the first cooler, and the pipeline at the gas output end of the tail gas absorption tower is connected to the de-RTO unit.

[0006] Preferably, a de-singling tower reboiler is provided on one side of the de-singling tower, a branch pipe in the DMSO feed pipe is interconnected with the de-singling tower reboiler, one of the output ends of the de-singling tower reboiler is interconnected with the de-singling tower, the pipeline at the other output end is connected with a DMSO waste tank, the pipeline between the de-singling tower reboiler and the DMSO waste tank is connected with a de-singling tower reboiler discharge pump, the pipeline at the output end of the DMSO waste tank is connected with a waste DMSO discharge pump, and the pipeline at the output end of the waste DMSO discharge pump is connected to a DMSO removal recovery unit.

[0007] Preferably, a de-singling tower condenser is connected to the pipe at the gas output end of the top of the de-singling tower, and two output pipes are arranged on the de-singling tower condenser, wherein the pipe at one output end is connected to a de-singling condensate tank, and the pipe at the output end of the de-singling condensate tank is connected to the inside of the de-singling tower condenser, and the pipe between the de-singling condensate tank and the de-singling tower condenser is connected to a de-singling condensate discharge pump, and the pipe at the other output end of the de-singling tower condenser is connected to a first ejector, and the pipe at the output end of the first ejector is connected to a DMSO tank for de-singling, and the pipe at the output end of the DMSO tank for de-singling is connected to a second cooler, and the pipe between the DMSO tank for de-singling and the second cooler is connected to a DMSO discharge pump for de-singling, and the pipe at the output end of the second cooler is connected to the first ejector.

[0008] Preferably, a deaeration tower condenser is connected to the pipeline at the gas output end of the deaeration tower top, two output end pipelines are arranged on the deaeration tower condenser, wherein the pipeline at one output end is connected to a deaeration condensate tank, the pipeline at the output end of the deaeration condensate tank is connected to the inside of the deaeration tower condenser, the pipeline between the deaeration condensate tank and the desingle tower condenser is connected to a deaeration condensate discharging pump, the pipeline at the other output end of the deaeration tower condenser is connected to a second ejector, the pipeline at the output end of the second ejector is connected to a DMSO tank for deaeration, the pipeline at the output end of the DMSO tank for deaeration is connected to the third cooler, the pipeline between the DMSO tank for deaeration and the third cooler is connected to a DMSO discharging pump for deaeration, the pipeline at the output end of the 3rd cooler is connected to the second ejector, and the pipeline at the liquid output end in the tail gas absorption tower is connected to the DMSO tank for deaeration.

[0009] Preferably, filters are provided at the ends of the two groups of DMSO feed pipes and on the pipes connecting the three first feed pumps to the polymerization kettle respectively.

[0010] Preferably, the polymerization kettle, the end-capping agent storage tank, the first polymer storage tank, the second polymer storage tank and the de-singling tower reboiler are injected with water vapor by means of an inner coil, the jackets of the preparation tank and the feed tank are injected with water vapor for heat exchange, and the other sides of the preparation tank, the feed tank, the polymerization kettle, the end-capping agent storage tank, the first polymer storage tank, the de-singling tower reboiler and the second polymer storage tank are provided with pipes for discharging condensed water, and nitrogen is injected into the interior of the preparation tank, the feed tank and the polymerization kettle for deoxygenation treatment, while being able to maintain a slight positive pressure inside the tank body in the range of 0.05kPa to 0.06kPa.

[0011] Preferably, a group of parallel pipes for flushing nitrogen are arranged on the first polymer storage tank, DMSO waste tank, depolymerization condensate tank, depolymerization DMSO tank, degassing condensate tank, degassing DMSO tank and the second polymer storage tank; the temperature inside the depolymerization tower is 60-80°C, and the pressure inside the tower is 0.2-1KPa; the temperature inside the degassing tower is 45-65°C, and the pressure inside the tower is 0.3-2KPa.

[0012] A production method capable of accurately regulating the molecular weight and distribution of carbon fiber stock solution, comprising the following steps:

[0013] Step 1: Add raw materials in proportion, add 14-19wt.% of itaconic acid (IA) to the first configuration tank, add 4-7wt.% of azobisisobutyronitrile (AIBN) to the second configuration tank, add 1-2wt.% of cyanoisopropyl dithiobenzoate (CPED) to the third configuration tank, and add 98-99wt.% of ethylene carbonate (EC) to each batch of ethylene carbonate (EC). Dimethyl sulfoxide (DMSO) is added as a solvent to the above three tanks.

[0014] Step 2: Prepare uniform itaconic acid solution, AIBN solution and CPED solution. In the steps, the feeding time for preparing itaconic acid solution is 20 to 40 minutes, the feeding time for preparing AIBN solution is 15 to 30 minutes, and the feeding time for preparing isopropyl cyanodithiobenzoate (CPED) solution is 20 to 40 minutes. The temperature in the above steps is 60 to 70°C, the stirring rate is 100 to 130 r / min, and stirring is performed for 20 to 40 hours after the feeding is completed. After the solution is prepared, it enters three feed tanks respectively, and the stirring speed in the feed tank is 60 to 80 r / min, and the raw materials are stirred all the time in the three feed tanks.

[0015] Step 3: The liquids in the three feed tanks are respectively fed into the polymerization kettle through the first feed pump for polymerization reaction. The feeding time of dimethyl sulfoxide (DMSO) is 50 to 80 minutes, and the input ratio of dimethyl sulfoxide (DMSO) in each batch is 79 to 82 wt.%; the feeding time of acrylonitrile (AN) is 20 to 30 minutes, and the input ratio of acrylonitrile (AN) in each batch is 18 to 22 wt.%; the feeding time of itaconic acid (IA) solution is 15 to 30 minutes, and the input ratio of itaconic acid in each batch is 18 to 22 wt.%. The input ratio of (IA) is 0.4-0.6wt.%; the feeding time of each batch of cyanoisopropyl dithiobenzoate (CPED) solution is 15-30min, and the input ratio of cyanoisopropyl dithiobenzoate (CPED) is 0.3-0.4wt.%; the feeding time of each batch of azobisisobutyronitrile (AIBN) is 15-30min, and the input ratio of azobisisobutyronitrile (AIBN) solution is 0.2-0.3wt.%, and the polymerization is carried out in a polymerization kettle for 16-30 hours.

[0016] Step 4: After the polymerization is completed, open the end-capping agent storage tank, add the internal benzyl alcohol end-capping agent into the polymerization kettle to stop the internal polymerization reaction, the feeding time of the benzyl alcohol end-capping agent is 10 to 15 minutes, and the input amount of each batch of benzyl alcohol end-capping agent is 0.4 to 0.6 wt.% of the total mass.

[0017] Step 5: The polymer after polymerization is discharged into the first polymer storage tank at the bottom, and then sent to the single removal tower on one side for single removal treatment, and then sent to the degassing tower on one side for degassing treatment, and finally discharged into the second polymer storage tank for storage for use in the spinning unit.

[0018] The present invention has the following beneficial effects: The present invention obtains the target molecular weight by changing the feed amount and reaction conditions, thereby improving controllability and spinnability and facilitating the production of the target product. At the same time, the solvent recovery system reduces material consumption and reduces the production cost of raw materials, and the RTO waste gas treatment system reduces environmental pollution, meeting the requirements of green production. Automated control improves the stability and repeatability of production. In addition, the use of soluble metal catalysts is not involved, which avoids metal ion residues in the polymer product, and the product has more advantages in the application fields of high-performance fibers, biomedical materials, and electrical devices.

[0019] This patent adopts a DCS system, which realizes automation and precise control of the production process by real-time monitoring and control of key parameters in the production process, such as temperature, pressure, flow, etc. For example, a temperature sensor is arranged on the cooler, polymerization kettle and storage tank to obtain the internal temperature of the equipment. The control system is connected to the temperature sensor and is used to control the temperature control system according to the temperature obtained by the temperature sensor. A pressure sensor is arranged on the polymerization kettle and storage tank to obtain the internal pressure of the equipment. The control system is connected to the pressure sensor and is used to control the pressure system according to the pressure obtained by the pressure sensor. Through the integration and automatic control of the DCS system, production efficiency can be improved, manual intervention can be reduced, and product consistency and quality can be guaranteed. In addition, DCS can also monitor and manage the status of production equipment, prevent equipment failures, reduce downtime, and improve production continuity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of a process structure of the raw material monomer configuration of the present invention;

[0021] Figure 2 It is a schematic diagram of the process structure of the polymerization reaction of the present invention.

[0022] In the figure: 1, preparation tank; 101, feed tank; 102, first feed pump; 103, filter; 2, polymerization kettle; 201, end-capping agent storage tank; 3, first polymer storage tank; 4, polymer discharge pump; 5, polymer mixer; 6, depolymerization tower reboiler; 7, depolymerization tower; 8, depolymerization tower discharge pump; 9, depolymerization tower condenser; 10, first ejector; 11, second cooler; 12, degassing tower; 13, first degassing tower discharge pump; 14, degassing tower condenser; 15, first cooler; 16, second ejector; 17, tail gas absorption tower; 18, third cooler Cooling device; 19, discharge pump of reboiler of degassing tower; 110, DMSO waste tank; 111, waste DMSO discharge pump; 112, degassing condensate tank; 113, degassing condensate discharge pump; 114, DMSO tank for degassing; 115, DMSO discharge pump for degassing; 116, degassing discharge mixer; 117, discharge pump of second degassing tower; 118, degassing condensate tank; 119, degassing condensate discharge pump; 120, degassing DMSO tank; 121, degassing DMSO discharge pump; 122, second polymer storage tank; 123, despinning polymer discharge pump. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0024] Embodiment: A production system capable of precisely controlling the molecular weight and distribution of carbon fiber stock solution, such as Figure 1-Figure 2As shown, it comprises three preparation tanks 1, each of which has a separate feed tank 101 connected to its output end, each of which has a first feed pump 102 connected to its output end pipeline, a polymerization kettle 2 connected to its output end pipeline, a blocking agent storage tank 201 connected to one side of the polymerization kettle 2, a first polymerization kettle material storage tank 3 connected to its output end pipeline, a connecting pipe for balancing the pressure between the polymerization kettle 2 and the first polymerization kettle material storage tank 3 is connected externally between the polymerization kettle 2 and the first polymerization kettle material storage tank 3, and the first polymerization kettle material storage tank 3 is connected to its output end pipeline. The pipeline at the output end of the combined still material storage tank 3 is connected to a polymer mixer 5, the pipeline between the first polymerization still material storage tank 3 and the polymer mixer 5 is connected to a polymer discharge pump 4, the pipeline at the output end of the polymer mixer 5 is connected to a stripping tower 7, the pipeline at the output end of the stripping tower 7 is connected to a degassing tower 12, the pipeline between the stripping tower 7 and the degassing tower 12 is connected to a stripping tower discharge pump 8, the pipeline at the output end of the degassing tower 12 is connected to a degassing discharge mixer 116, and the pipeline between the degassing tower 12 and the degassing discharge mixer 116 is connected to the polymer mixer 5. The first degassing tower discharge pump 13 is connected to the top, the pipeline at the output end of the degassing discharge mixer 116 is connected to the second polymerization kettle material storage tank 122, the pipeline between the degassing discharge mixer 116 and the second polymerization kettle material storage tank 122 is connected to the second degassing tower discharge pump 117, the pipeline at the output end of the second polymerization kettle material storage tank 122 is connected to the despinning polymer discharge pump 1234, and the pipeline at the output end of the despinning polymer discharge pump 1234 is connected to the despinning unit. A group of DMSO feed pipe, the output end of the DMSO feed pipe main pipeline is connected to the first cooler 15, the pipeline at the output end of the first cooler 15 is provided with a tail gas absorber 17, the pipeline at the gas output end of the tail gas absorber 17 is connected to the RTO removal unit, and a group of parallel pipelines for flushing nitrogen are arranged on the first polymer storage tank 3, the DMSO waste tank 110, the depolymerization condensate tank 112, the depolymerization DMSO tank 114, the degassing condensate tank 118, the degassing DMSO tank 120 and the second polymer storage tank 122. At the same time, the corresponding steps are:

[0025] 1. Water vapor is injected into the jackets of three preparation tanks 1 to perform heat exchange treatment, then itaconic acid (IA) and dimethyl sulfoxide (DMSO) are added to the first preparation tank to prepare a 14-19 wt. % IA-DMSO solution, azobisisobutyronitrile (AIBN) and dimethyl sulfoxide (DMSO) are added to the second preparation tank to prepare a 4-7 wt. % AIBN-DMSO solution, cyanoisopropyl dithiobenzoate (CPED) and dimethyl sulfoxide (DMSO) are added to the third preparation tank, and ethylene carbonate (EC) is added at the same time. The activity of CPED can be stimulated. The two can be used together to make the reaction smoother, and polymers with ideal molecular weight and molecular weight distribution can be better prepared to make 1-2wt.% CPED-ED solutions. The solutions prepared in the above three configuration tanks are injected into the corresponding feed tanks 101 below. When the configuration tanks and the feed tanks 101 are reacting, nitrogen is injected into the inside for deoxygenation treatment. Finally, they are injected into the polymerization kettle 2 through the corresponding first feed pumps 102. A group of feed tanks 101 for storing raw materials are arranged between the configuration tank 1 and the polymerization kettle 2, and the raw materials are stirred at a speed of 60-80r / min inside.

[0026] 2. When the raw materials in the three feed tanks 101 are injected into the polymerization kettle 2, water vapor is injected into the interior, and the internal temperature is heated to 60-80° C. in coordination with the internal coil, and acrylonitrile (AN) solution and dimethyl sulfoxide (DMSO) solution are injected at the same time to carry out polymerization reaction. During the polymerization reaction, nitrogen is injected into the polymerization kettle 2 for deoxygenation treatment, and stirring is carried out at the same time. The stirring speed is 120 r / min. When the polymerization in the polymerization kettle 2 is completed after waiting for 16-30 hours for the polymerization to be completed, benzyl alcohol capping agent is injected into the polymerization kettle 2 through the capping agent storage tank 201 on one side to stop the internal polymerization reaction.

[0027] 3. The polymer after the reaction is transported to the first polymer storage tank 3 through the polymer discharge pump 4, and then enters the polymer mixer 5 to fully mix the materials. The mixed materials enter the stripping tower 7 to remove the unreacted acrylonitrile. The temperature in the stripping tower 7 is 60-80°C, and the pressure in the tower is 0.2-1KPa. In the stripping step, it is necessary to control the vacuum degree to reduce the boiling point of the monomer, so that the monomer can be more easily volatilized from the polymerization liquid, thereby achieving effective removal. At this time, a stripping tower condenser 9 is connected to one side of the stripping tower 7, and a stripping condensate tank 112 for storing the condensed liquid is connected to the bottom of the stripping tower condenser 9, which cooperates with the stripping condensate discharge pump 113 at the bottom to The liquid is circulated between the de-monomer condensate tank 112 and the de-monomer tower condenser 9. One side of the de-monomer tower condenser 9 is interconnected with the first ejector 10. Since the injection fluid velocity is particularly high, the pressure energy is converted into velocity energy, so that the pressure in the suction zone is reduced to generate a vacuum. The non-condensable gas in the de-monomer tower condenser 9 is sucked into the first ejector 10. At the same time, the second cooler 11 interconnected with the first ejector 10 can cool the temperature of DMSO to ensure the normal operation of the first ejector 10. After completing the suction process, the DMSO in the ejector enters the DMSO tank for storage of DMSO, and is transported and circulated by the de-monomer DMSO discharge pump 115, thereby achieving the effect of continuous vacuum generation. Through the above principle, the vacuum ejector unit maintains the stable pressure at the top of the vacuum tower during carbon fiber production to ensure the uniformity of the polymerization stock solution. Nitrogen is injected into the interior of the de-monomer condensate tank 112 and the de-monomer DMSO tank 114 for de-monomerization to perform deoxygenation treatment. During the de-monomerization process, a de-monomerization tower reboiler 6 is connected on one side, and one end of the de-monomerization tower reboiler is connected to a DMSO injection pipe to replenish new DMSO solution into the de-monomerization tower 7. At the same time, the waste DMSO generated in the de-monomerization tower reboiler 6 is injected into the DMSO waste tank 110, and finally the DMSO is sent to the DMSO recovery unit through the waste DMSO discharge pump 111.

[0028] 4. After the degassing of the polymerized liquid is completed, it enters the degassing tower 12 through the discharge pump of the degassing tower 12. In the degassing step, it is necessary to control the vacuum degree to reduce the boiling point of the monomer. The gas in the bubbles is easier to escape under low pressure environment to avoid bubbles causing broken wires or affecting product performance in subsequent processes. The temperature in the degassing tower 12 is 45-65°C, and the pressure in the tower is 0.3-2KPa. At this time, a degassing tower condenser 14 is connected to one side of the degassing tower 12. The bottom of the degassing tower condenser 14 is connected to a degassing condensate tank 118 for storing the condensed liquid. The degassing condensate discharge pump at the bottom is used to store the liquid in the degassing condensate tank 118 and the degassing tower condenser. 14, one side of the degassing tower condenser 14 is interconnected with the second ejector 16. Since the velocity of the jet fluid is particularly high, the pressure energy is converted into velocity energy, so that the pressure in the suction zone is reduced to generate vacuum, and the non-condensable gas in the degassing tower condenser 14 is sucked into the second ejector 16. At the same time, the third cooler 18 interconnected with the second ejector 16 can cool the temperature of DMSO to ensure the normal operation of the second ejector 16. After the DMSO in the ejector completes the suction process, it enters the DMSO tank for storage of DMSO, and is transported and recycled by the degassing DMSO discharge pump 121, thereby achieving the effect of continuous vacuum generation. Through the above principle, the vacuum ejector unit maintains the stability of the top pressure of the degassing tower 12 in the production of carbon fiber, ensures the uniformity of the polymerization stock solution, and nitrogen is injected into the degassing condensate tank 118 and the degassing DMSO tank 120 for deoxygenation. After the bubbles in the polymer are removed, it enters the degassing discharge mixer 116 through the first degassing tower discharge pump 13. After mixing, it is transported to the second polymer storage tank 122 through the second degassing tower discharge pump 17. The spinning polymer discharge pump 123 transports the mixed polymer solution to the spinning unit.

[0029] A DMSO supplement system is provided in the stripping tower 7, comprising:

[0030] A de-singling tower reboiler 6 is provided on one side of the de-singling tower 7, a branch pipe in the DMSO feed pipe is interconnected with the de-singling tower reboiler 6, one of the output ends of the de-singling tower reboiler 6 is interconnected with the de-singling tower 7, and the pipeline at the other output end is connected to a DMSO waste tank 110, and the pipeline between the de-singling tower reboiler 6 and the DMSO waste tank 110 is connected to a de-singling tower reboiler discharge pump 19, and the pipeline at the output end of the DMSO waste tank 110 is connected to a waste DMSO discharge pump 111, and the pipeline at the output end of the waste DMSO discharge pump 111 is connected to a DMSO removal recovery unit.

[0031] The vacuum system of the stripping tower 7 includes:

[0032] The pipeline at the gas output end of the top of the de-singling tower 7 is connected to the de-singling tower condenser 9, and two output end pipelines are arranged on the de-singling tower condenser 9, one of the output end pipelines is connected to the de-singling condensate tank 112, and the pipeline at the output end of the de-singling condensate tank 112 is connected to the inside of the de-singling tower condenser 9, and the pipeline between the de-singling condensate tank 112 and the de-singling tower condenser 9 is connected to the de-singling condensate discharge pump 113, and the pipeline at the other output end of the de-singling tower condenser 9 is connected to the first ejector 10, and the first ejector 10 outputs The pipeline at the outlet end is connected to a DMSO tank 114 for removing single atoms, the pipeline at the output end of the DMSO tank 114 for removing single atoms is connected to a second cooler 11, the pipeline between the DMSO tank 114 for removing single atoms and the second cooler 11 is connected to a DMSO discharge pump 115 for removing single atoms, the pipeline at the output end of the second cooler 11 is connected to the first injector 10, and filters 103 are arranged on the ends of the two groups of DMSO feed pipes and the pipelines connecting the three first feed pumps 102 to the polymerization kettle 2 respectively.

[0033] Wherein the vacuum system of degassing tower 12 comprises:

[0034] A degassing tower condenser 14 is connected to the pipeline at the gas output end of the top of the degassing tower 12, and two output end pipelines are arranged on the condensation of the degassing tower 12, wherein a degassing condensate tank 118 is connected to the pipeline at one output end, and a pipeline at the output end of the degassing condensate tank 118 is connected to the inside of the degassing tower condenser 14, and a degassing condensate discharge pump 119 is connected to the pipeline between the degassing condensate tank 118 and the degassing tower condenser 14, and a second ejector 16 is connected to the pipeline at the other output end of the degassing tower condenser 14, and a degassing DMSO tank 120 is connected to the pipeline at the output end of the second ejector 16, and a third cooler 18 is connected to the pipeline at the output end of the degassing DMSO tank 120, and a degassing DMSO discharge pump 121 is connected to the pipeline between the degassing DMSO tank 120 and the third cooler 18, and the pipeline at the output end of the third cooler 18 is connected to the second ejector 16, and the pipeline at the liquid output end in the tail gas absorption tower 17 is connected to the degassing DMSO tank 120.

[0035] The molecular weight of the stock solution is measured by gel chromatography. First, dissolve the polyacrylonitrile sample in an appropriate solvent, turn on and preheat the gel chromatograph, including the high-pressure pump, chromatographic column and detector. Ensure that the flow rate is stable and adjusted to a range suitable for GPC analysis, usually not exceeding 1.0mL / min. Inject the sample solution into the chromatography system, and the molecular weight distribution of polyacrylonitrile can be obtained through the chromatogram, including parameters such as number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (Mw / Mn).

[0036] The conversion rate of the polymer was determined by the thin film method. The spinning solution sample was weighed by the reduction method, and spread into a uniform continuous film on a glass plate with a glass rod. The film was placed in an enamel basin filled with distilled water. After the film was formed, it was taken out and washed with distilled water in a beaker until it was neutral. It was wrung dry without losing any fragments. It was folded and placed on a watch glass, dried for 4 hours and weighed. The conversion rate was calculated based on the mass of the dry film, the mass of the spinning solution and the mass of the monomer feed. The following results were obtained from the analysis and detection:

[0037] Table 1 shows the results of the analysis of the original solution at different polymerization reaction times.

[0038]

[0039] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are 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 belong to the protection scope of the present invention.

Claims

1. A production system capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution, comprising three preparation tanks (1), characterized in that: A group of feed pipes for DMSO feeding are connected to the tops of the three preparation tanks (1), and a separate feed tank (101) is connected to the output end of each preparation tank (1), and a first feed pump (102) is connected to the pipeline at the output end of each feed tank (101). The pipelines at the output ends of the three first feed pumps (102) are connected to a polymerization kettle (2), and a capping agent storage tank (201) is connected to one side of the polymerization kettle (2). The pipeline at the output end of the polymerization kettle (2) is connected to the first polymerization kettle (102). A reactor material storage tank (3), a polymer mixer (5) is connected to the pipeline at the output end of the first polymerization reactor material storage tank (3), a polymer discharge pump (4) is connected to the pipeline between the first polymerization reactor material storage tank (3) and the polymer mixer (5), a single-removal tower (7) is connected to the pipeline at the output end of the polymer mixer (5), a degassing tower (12) is connected to the pipeline at the output end of the single-removal tower (7), a degassing tower (12) is connected to the pipeline between the single-removal tower (7) and the degassing tower (12), and a single-removal tower discharge pump (8) is connected to the degassing tower (1 2) a degassing discharging mixer (116) is connected to the pipeline at the output end, a first degassing tower discharging pump (13) is connected to the pipeline between the degassing tower (12) and the degassing discharging mixer (116), a second polymerizer storage tank (122) is connected to the pipeline at the output end of the degassing discharging mixer (116), a second degassing tower discharging pump (117) is connected to the pipeline between the degassing discharging mixer (116) and the second polymerizer storage tank (122), and a second degassing tower discharging pump (117) is connected to the pipeline at the output end of the second polymerizer storage tank (122). A despinning polymer discharge pump (123) is connected to the top, and the pipeline at the output end of the despinning polymer discharge pump (123) is connected to the despinning unit. Another group of DMSO feed pipes are arranged on the top of the polymerization kettle (2), the despinning tower (7) and the degassing tower (12). The output end of the DMSO feed pipe main pipeline is connected to a first cooler (15). A tail gas absorption tower (17) is arranged on the pipeline at the output end of the first cooler (15), and the pipeline at the gas output end of the tail gas absorption tower (17) is connected to the de-RTO unit.

2. A production system capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution according to claim 1, characterized in that: A de-DMSO tower reboiler (6) is provided on one side of the de-DMSO tower (7); a branch pipe in the DMSO feed pipe is interconnected with the de-DMSO tower reboiler (6); one of the output ends of the de-DMSO tower reboiler (6) is interconnected with the de-DMSO tower (7); a pipeline at the other output end is connected to a DMSO waste tank (110); a de-DMSO tower reboiler discharge pump (19) is connected to the pipeline between the de-DMSO tower reboiler (6) and the DMSO waste tank (110); a waste DMSO discharge pump (111) is connected to the pipeline at the output end of the DMSO waste tank (110); and a pipeline at the output end of the waste DMSO discharge pump (111) is connected to a DMSO recovery unit.

3. A production system capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution according to claim 1, characterized in that: The pipeline at the gas output end of the top of the de-singling tower (7) is connected to a de-singling tower condenser (9), and the de-singling tower condenser (9) is provided with two output end pipelines, one of which is connected to a de-singling condensate tank (112), and the pipeline at the output end of the de-singling condensate tank (112) is connected to the inside of the de-singling tower condenser (9), and the pipeline between the de-singling condensate tank (112) and the de-singling tower condenser (9) is connected to a de-singling condensate discharge pump (113), and the other of the de-singling tower condenser (9) is connected to a de-singling condensate tank (112). A first injector (10) is connected to the pipeline at the output end, a DMSO tank (114) for removing single molecules is connected to the pipeline at the output end of the first injector (10), a second cooler (11) is connected to the pipeline at the output end of the DMSO tank (114) for removing single molecules, a DMSO discharge pump (115) for removing single molecules is connected to the pipeline between the DMSO tank (114) for removing single molecules and the second cooler (11), and the pipeline at the output end of the second cooler (11) is connected to the first injector (10).

4. A production system capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution according to claim 1, characterized in that: The pipeline at the gas output end of the top of the degassing tower (12) is connected to a degassing tower condenser (14); the degassing tower (12) condenser is provided with two output end pipelines, one of the output end pipelines is connected to a degassing condensate tank (118); the pipeline at the output end of the degassing condensate tank (118) is connected to the inside of the degassing tower condenser (14); the pipeline between the degassing condensate tank (118) and the degassing tower condenser (14) is connected to a degassing condensate discharge pump (119); the pipeline at the other output end of the degassing tower condenser (14) is connected to a second ejector (119); 6), the pipeline at the output end of the second ejector (16) is connected to a DMSO tank (120) for degassing, the pipeline at the output end of the DMSO tank (120) for degassing is connected to a third cooler (18), the pipeline between the DMSO tank (120) for degassing and the third cooler (18) is connected to a DMSO discharge pump (121) for degassing, the pipeline at the output end of the third cooler (18) is connected to the second ejector (16), and the pipeline at the liquid output end of the tail gas absorption tower (17) is connected to the DMSO tank (120) for degassing.

5. The production system capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution according to claim 1, characterized in that: Filters (103) are provided at the ends of the two groups of DMSO feed pipes and on the pipes connecting the three first feed pumps (102) and the polymerization kettle (2) respectively.

6. A production system capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution according to claim 2, characterized in that: The polymerization kettle (2), the end-capping agent storage tank (201), the first polymer storage tank (3), the second polymer storage tank (122) and the depolymerization tower reboiler (6) are injected with water vapor through an inner coil, and the jackets of the preparation tank (1) and the feed tank (101) are injected with water vapor for heat exchange, and the other side of the preparation tank (1), the feed tank (101), the polymerization kettle (2), the end-capping agent storage tank (201), the first polymer storage tank (3), the depolymerization tower reboiler (6) and the second polymer storage tank (122) are provided with pipes for discharging condensed water, and nitrogen is injected into the interior of the preparation tank (1), the feed tank (101) and the polymerization kettle (2) for deoxygenation treatment, while maintaining a slight positive pressure inside the tank body in the range of 0.05 kPa to 0.06 kPa.

7. A production system capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution according to claim 1, 2, 3 or 4, characterized in that: A group of parallel pipes for flushing nitrogen are arranged on the first polymer storage tank (3), the DMSO waste tank (110), the depolymerization condensate tank (112), the depolymerization DMSO tank (114), the degassing condensate tank (118), the degassing DMSO tank (120) and the second polymer storage tank (122). The temperature in the depolymerization tower (7) is 60-80°C and the pressure in the tower is 0.2-1 KPa. The temperature in the degassing tower (12) is 45-65°C and the pressure in the tower is 0.3-2 KPa.

8. A production method capable of accurately controlling the molecular weight and distribution of carbon fiber stock solution, the steps comprising: Step 1: Add raw materials in proportion, add 14-19 wt.% of itaconic acid (IA) to the first configuration tank, add 4-7 wt.% of azobisisobutyronitrile (AIBN) to the second configuration tank, add 1-2 wt.% of cyanoisopropyl dithiobenzoate (CPED) to the third configuration tank, and add 98-99 wt.% of ethylene carbonate (EC) to the third configuration tank. Dimethyl sulfoxide (DMSO) is added as a solvent to the three tanks. Step 2: Prepare uniform itaconic acid solution, AIBN solution and CPED solution. In the steps, the feeding time for preparing the itaconic acid solution is 20-40 min, the feeding time for preparing the AIBN solution is 15-30 min, and the feeding time for preparing the dithiobenzoic acid cyanoisopropyl ester (CPED) solution is 20-40 min. The temperature in the above steps is 60-70 °C, the stirring rate is 100-130 r / min, and stirring is performed for 20-40 h after the feeding is completed. After the solution is prepared, it enters three feed tanks (101) respectively, and the stirring speed in the feed tank (101) is 60-80 r / min. The raw materials are stirred in the three feed tanks (101); Step 3: The liquids in the three feed tanks (101) are respectively fed into the polymerization kettle (2) through the first feed pump (102) for polymerization reaction. The feeding time of dimethyl sulfoxide (DMSO) is 50-80 min, and the input ratio of dimethyl sulfoxide (DMSO) in each batch is 79-82 wt.%; the feeding time of acrylonitrile (AN) is 20-30 min, and the input ratio of acrylonitrile (AN) in each batch is 18-22 wt.%; the feeding time of itaconic acid (IA) solution is 15-30 min, and the input ratio of itaconic acid (IA) in each batch is 0.4-0.6 wt.%; the feeding time of cyanoisopropyl dithiobenzoate (CPED) solution in each batch is 15-30 min, and the input ratio of cyanoisopropyl dithiobenzoate (CPED) is 0.3-0.4 wt.%; the feeding time of azobisisobutyronitrile (AIBN) in each batch is 15-30 min. min, the input ratio of azobisisobutyronitrile (AIBN) solution is 0.2-0.3 wt.%, and the polymerization is carried out in the polymerization reactor (2) for 16-30 hours; Step 4: After the polymerization is completed, the end-capping agent storage tank (201) is opened, and the benzyl alcohol end-capping agent inside is added to the polymerization kettle (2) to stop the internal polymerization reaction. The feeding time of the benzyl alcohol end-capping agent is 10-15 min, and the input amount of each batch of benzyl alcohol end-capping agent is 0.4-0.6 wt.% of the total mass; Step 5: The polymer after polymerization is discharged into the first polymer storage tank (3) at the bottom, and then sent to the single removal tower (7) on one side for single removal treatment, and then sent to the degassing tower (12) on one side for degassing treatment, and finally discharged into the second polymer storage tank (122) for storage for use in the spinning unit.

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