System for recycling and treating waste liquid in carbon fiber industry

Abstract

The utility model discloses a system for recycling and treating waste liquid in the carbon fiber industry. The system comprises a spinning dilute solvent pretreatment unit and a receipt solution pre-separation unit, the spinning dilute solvent pretreatment unit comprises at least one stage of dehydrating tower; the receipt solution pre-separation unit comprises a pretreatment tower TVII; the tower top of the pretreatment tower TVII leads to an acrylonitrile refining tower TVIII; the tower kettle of the last stage of dehydration tower and the tower kettle of the pretreatment tower TVII are both led to a core residue removal device, the discharge port of the core residue removal device is led to a deep dehydration tower TV, and the tower kettle of the deep dehydration tower TV is led to a DMSO refining tower TVI. According to the utility model, the carbon fiber receipt solution and the spinning dilute solvent are combined to obtain ultra-high-purity acrylonitrile, DMSO and process water, and the ultra-high-purity acrylonitrile, DMSO and process water can be returned to carbon fiber production for use.

Description

Technical Field

[0001] The utility model belongs to the field of chemical industry, relates to solvent recovery, and specifically relates to a system for resource-based combined treatment of waste liquid in the carbon fiber industry. Background Art

[0002] Carbon fiber is a high-strength, high-modulus fiber with a carbon content exceeding 90%. Its high-temperature resistance is the highest among all chemical fibers. Currently, the main products are polyacrylonitrile-based, asphalt-based, and viscose-based. Both the spinning and polymerization stages of nitrile-based carbon fibers require the use of organic solvents, of which DMSO (dimethyl sulfoxide) is the most commonly used solvent.

[0003] The wastewater generated by the carbon fiber spinning section is a dilute DMSO solvent, the main components of which are water and DMSO, as well as trace amounts of acrylonitrile, ammonia, methyl acrylate, polymers, tar, etc., with the DMSO content usually ranging from 8wt% to 55wt%. The return solution generated by the polymerization section (i.e., the monomer-containing solution generated by the carbon fiber polymerization section) contains acrylonitrile, DMSO, and water, with the acrylonitrile content usually ranging from 0.8wt% to 10.2wt%, the DMSO content usually ranging from 72wt% to 96wt%, and the water content usually ranging from 0.2wt% to 4.5wt%.

[0004] At present, the recovery of the DMSO dilute solvent produced in the spinning section of carbon fiber is usually limited to the recovery of DMSO. Not only is a large amount of water not recovered, but it also requires further biochemical treatment before it can be discharged, causing economic losses and environmental pressure. In addition, there is room for further reduction in the energy consumption of the recovery process of such wastewater. The return single solution produced in the polymerization section is usually directly returned to the polymerization section for use; however, with the upgrading of the carbon fiber production process, its purity can no longer meet the process requirements. If the return single solution is only simply separated, the acrylonitrile returned for use contains DMSO, and the DMSO contains acrylonitrile, which seriously affects the quality indicators of the returned use; if deep treatment is performed separately, it will incur large equipment costs and energy consumption.

[0005] In view of this, if the recycling of the two waste liquids in the carbon fiber industry can be achieved at the same time, it will produce considerable economic and environmental benefits. Utility Model Content

[0006] In response to the deficiencies in the above-mentioned prior art, the utility model provides a system for resource-based combined treatment of waste liquids from the carbon fiber industry, so as to realize the combined recovery of wastewater from the spinning section and return solution generated in the polymerization section in carbon fiber production, thereby obtaining high-purity DMSO, acrylonitrile and process water products.

[0007] The specific technical solutions are as follows:

[0008] The purpose of the utility model is to provide a system for resource-based combined treatment of waste liquid in the carbon fiber industry, which includes a spinning dilute solvent pretreatment unit and a return single solution pre-separation unit;

[0009] The spinning dilute solvent pretreatment unit includes at least one dehydration tower;

[0010] The return single solution pre-separation unit includes a pretreatment tower TVII; the top of the pretreatment tower TVII leads to the acrylonitrile refining tower TVIII;

[0011] The kettle of the last stage dehydration tower and the kettle of the pretreatment tower TVII are both led to the core dehydration device, the discharge port of the core dehydration device is led to the deep dehydration tower TV, and the kettle of the deep dehydration tower TV is led to the DMSO refining tower TVI;

[0012] The dehydration tower, deep dehydration tower TⅤ, DMSO refining tower TⅥ, pretreatment tower TⅦ and acrylonitrile refining tower TⅧ are all distillation towers;

[0013] The core residue removal device is used to remove heavy components such as polymers;

[0014] The pretreatment tower TVII is used for pre-separating DMSO and acrylonitrile.

[0015] The spinning solvent is DMSO produced in the carbon fiber spinning process, which is mainly composed of water and DMSO, and also contains trace amounts of acrylonitrile, ammonia, methyl acrylate, polymers, tar, etc. The DMSO content in the spinning solvent is 8wt% to 55wt%.

[0016] The return single solution refers to the monomer-containing solution produced in the carbon fiber polymerization process. The main components of the return single solution are acrylonitrile, DMSO, and water. The acrylonitrile content in the return single solution is generally 0.8wt% to 10.2wt%, the DMSO content is generally 72wt% to 96wt%, and the water content is generally 0.2wt% to 4.5wt%.

[0017] The utility model combines the spinning dilute solvent and the return single solution for recycling. When using the above system:

[0018] The spinning solvent enters the spinning solvent pretreatment unit for dehydration. A core dehydration system is located between the spinning solvent pretreatment unit and the deep dehydration tower (TV), removing heavy components such as polymers, tar, and residues. The residual heavy component liquid is discharged as hazardous waste. The dehydrated liquid proceeds to the deep dehydration tower (TV) for deep dehydration. The water content of the dehydrated DMSO product is controlled below 100 ppm. The bottom of the deep dehydration tower (TV) contains solvent with a qualified water content, which is then sent to the DMSO refining tower (TV) for deep refining, resulting in a high-purity DMSO product at the top of the tower.

[0019] The return solution is pumped to pretreatment tower TVII, where DMSO-free crude acrylonitrile is obtained at the top of the tower; crude DMSO is obtained in the bottom of the tower. The overhead material is sent to acrylonitrile refining tower TVIII for deep purification of acrylonitrile, where qualified acrylonitrile product is obtained in the bottom of the tower and can be returned to the carbon fiber polymerization section. The bottom of the tower is combined with the core residual removal device for spinning dilute solvent treatment to remove heavy substances, and high-purity DMSO product is obtained at the top of DMSO refining tower TVI.

[0020] Furthermore, the top of the acrylonitrile refining tower TⅧ is connected to the pretreatment tower TⅦ. After the crude acrylonitrile is deeply purified in the acrylonitrile refining tower TⅧ, a qualified gaseous product is obtained in the bottom of the tower, and the unqualified product at the top is returned to the pretreatment tower TⅦ for further treatment.

[0021] Furthermore, the spinning dilute solvent pretreatment unit includes a decontamination tower TI, a primary dehydration tower TII, a secondary dehydration tower TIII and a tertiary dehydration tower TIV in sequence according to the flow direction of the tower bottom material;

[0022] Wherein, the decontamination tower TI is a distillation tower used to remove water containing light components.

[0023] The spinning dilute solvent enters the decontamination tower TⅠ, and the wastewater containing light components and water is obtained at the top of the tower. This part of the wastewater is subjected to biochemical treatment. The feed liquid in the bottom of the decontamination tower TⅠ is a solvent containing a large amount of water, DMSO, and a trace amount of residue, which enters the dehydration towers at each level in sequence.

[0024] Furthermore, the top water outlets of the primary dehydration tower TII, the secondary dehydration tower TIII, and the tertiary dehydration tower TIV all lead to process water tanks. The water removed from the primary dehydration tower TII, the secondary dehydration tower TIII, and the tertiary dehydration tower TIV can be recycled as process water back to the carbon fiber spinning section.

[0025] More preferably, the process water tank leads to a carbon fiber spinning system.

[0026] Furthermore, the top outlet of the decontamination tower TI leads to a wastewater tank. The wastewater extracted from the top of the decontamination tower TI contains impurities and cannot be used as process water, so it enters the wastewater tank.

[0027] More preferably, the wastewater tank leads to a biochemical treatment system to treat the wastewater removed by the decontamination tower TI.

[0028] Furthermore, the overhead steam outlets of the decontamination tower TI, primary dehydration tower TII, and secondary dehydration tower TIII all flow to the next-stage distillation tower. To optimize energy utilization, the operating pressures of these towers are sequentially reduced, employing a downstream coupling process: steam generated at the top of tower TI heats the bottom of tower TII; steam generated at the top of tower TII heats the bottom of tower TIII; and steam generated at the top of tower TIII heats the bottom of tower TIV. It is important to note that the moisture content of the bottom of tower TIV must not be less than 5wt% to achieve this coupling process.

[0029] Furthermore, the spinning dilute solvent pretreatment unit includes a primary dehydration tower Tα and a secondary dehydration tower Tβ in sequence according to the flow direction of the tower bottom material; the tops of the primary dehydration tower Tα and the secondary dehydration tower Tβ are both connected to steam compressors, which pressurize the steam at the top of the towers and then couple themselves.

[0030] In the aforementioned spinning solvent pretreatment unit scheme, the process steam generated at the top of the primary dehydration tower Tα is pressurized by a steam compressor and then thermally auto-coupled. The compressor at the top of the primary dehydration tower Tα utilizes a high-flow, low-pressure ratio compressor. The process steam generated at the top of the secondary dehydration tower Tβ is pressurized by a steam compressor and then thermally auto-coupled. The compressor at the top of the secondary dehydration tower Tβ utilizes a low-flow, high-pressure ratio compressor, reducing power consumption. This significantly reduces power consumption while saving steam energy. It should be noted that the moisture content of the material in the bottom of the secondary dehydration tower Tβ must not be less than 5wt% to complete the above coupling operation.

[0031] Furthermore, the top of the first dehydration tower Tα is connected to two parallel steam compressors, and the top of the second dehydration tower Tβ is connected to two parallel steam compressor groups, wherein the steam compressor groups are multiple steam compressors connected in series. Each steam compressor group preferably has two steam compressors connected in series.

[0032] Since the operating flexibility of compressors is relatively low (generally 85% to 105%), single compression is usually considered in engineering. However, the solution of the present invention considers two parallel compressors or two parallel compressor groups for a tower system, and the operating flexibility can be optimized to 50% to 120%. The operation is more convenient and the flexibility is easier to adjust.

[0033] Furthermore, the top water outlets of the primary dehydration tower Tα and / or the secondary dehydration tower Tβ are connected to the process water tank. If the light components in the spinning solvent are very small, the water removed from the top of the two dehydration towers can be returned to the carbon fiber spinning system as process water.

[0034] Furthermore, the steam outlet at the top of the DMSO refining tower TVI is connected to the core desulfurization device. The steam generated at the top of the DMSO refining tower TVI is used to heat the core desulfurization device.

[0035] Wherein, the core debonding device is preferably a deweighting device.

[0036] Furthermore, the top water outlet of the deep dehydration tower TV leads to a process water tank or a biochemical treatment system. Depending on the process of the preceding polymerization stage, the dilute solvent solution may contain trace amounts of intermediate impurities. If these impurities are not removed and circulate within the system, they will gradually affect the product performance of the carbon fiber. The process water removed from the top of the deep dehydration tower TV has two destinations depending on the composition of the dilute solvent. If it contains intermediate impurities, this wastewater is sent to the biochemical system together with the wastewater from the decontamination tower TI. If the dilute solvent does not contain intermediate impurities, this process water can be returned to the carbon fiber spinning system for recycling.

[0037] Furthermore, the system for resource-based and combined treatment of waste liquid in the carbon fiber industry also includes a dilute solvent wastewater raw material tank for storing dilute solvent wastewater from the carbon fiber spinning section; the dilute solvent wastewater raw material tank leads to the spinning dilute solvent pretreatment unit.

[0038] Furthermore, the system for resource-based and combined treatment of waste liquid from the carbon fiber industry also includes a return single solution mother liquor tank for storing the return single solution from the carbon fiber polymerization section; the return single solution mother liquor tank leads to the pretreatment tower TⅦ.

[0039] The present invention also provides a method for resource-based combined treatment of waste liquid from the carbon fiber industry using the above-mentioned system for resource-based combined treatment of waste liquid from the carbon fiber industry, which comprises the following steps:

[0040] S1. Carbon fiber spinning dilute solvent treatment: Carbon fiber spinning dilute solvent is fed from the spinning dilute solvent pretreatment unit and subjected to distillation and dehydration. The dehydrated material is removed from the core residue removal device to remove heavy components, then enters the deep dehydration tower TⅤ for dehydration, and then goes to the DMSO refining tower TⅥ for refining, and the DMSO product is obtained at the top of the tower;

[0041] S2. Treatment of return solution from carbon fiber polymerization section: the return solution enters pretreatment tower TⅦ for distillation and pre-separation, crude DMSO is obtained in the bottom of the tower, and crude acrylonitrile is obtained at the top of the tower; the crude DMSO enters the core deresidue device, and the heavy components are removed together with the material dehydrated by the spinning dilute solvent pretreatment unit in step S1; the crude acrylonitrile enters acrylonitrile refining tower TⅧ for refining, and the acrylonitrile product is obtained in the bottom of the tower.

[0042] Furthermore, in step S2: the top material of the acrylonitrile refining tower TⅧ is preferably returned to the pretreatment tower TⅦ for further treatment.

[0043] Furthermore, in step S1: the water discharged from the top outlet of the dehydration tower in the spinning dilute solvent pretreatment unit is preferably returned to the carbon fiber spinning section for recycling.

[0044] Furthermore, in step S2: the obtained acrylonitrile product is preferably returned to the carbon fiber polymerization section for recycling.

[0045] The beneficial effects of the utility model are as follows:

[0046] This utility model combines carbon fiber return solution with a spinning dilute solvent to produce ultra-high-purity acrylonitrile and DMSO. The DMSO has a purity of ≥99.995%, and the acrylonitrile has a purity of ≥99.5%. These can be returned to the carbon fiber polymerization process, resulting in a carbon fiber product with ultra-high quality indicators. This utility model also produces high-purity process water with a purity of ≥99.995%, which can be returned to the carbon fiber spinning process. This utility model utilizes a 6-tower, 6-effect solution or a 4-tower compressor solution, addressing the high energy consumption of non-compressor solutions for solvent recovery in the carbon fiber industry, while achieving low temperatures and energy consumption. The 6-tower, 6-effect solution consumes 36% less energy than conventional solutions. Based on DMSO as the product and a 25wt% DMSO dilute solvent concentration, the spinning dilute solvent recovery circuit consumes only 1.6 tons of steam per ton of product. The 4-tower compressor solution consumes even less energy. Based on DMSO as the product and a 25wt% DMSO dilute solvent concentration, the spinning dilute solvent recovery circuit consumes only 0.85 tons of steam per ton of product. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a schematic diagram of the system for resource-based combined treatment of waste liquid from the carbon fiber industry in Example 1;

[0048] Figure 2 This is a schematic diagram of the system for resource-based combined treatment of waste liquid from the carbon fiber industry in Example 2;

[0049] In the figure: 1. Decontamination tower TI; 2. Primary dehydration tower TII; 3. Secondary dehydration tower TIII; 4. Tertiary dehydration tower TIV; 5. Core residue removal device; 6. Deep dehydration tower TV; 7. DMSO refining tower TVI; 8. Process water tank; 9. Wastewater tank; 10. Dilute solvent wastewater raw material tank; 11. Return single solution mother liquor tank; 12. Pretreatment tower TVII; 13. Acrylonitrile refining tower TVIII; 14. Biochemical treatment system; 15. Carbon fiber spinning system; 16. Carbon fiber polymerization system; 17. Primary dehydration tower Tα; 18. Secondary dehydration tower Tβ; 19. Primary steam compressor; 20. Secondary steam compressor unit. DETAILED DESCRIPTION

[0050] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0051] Example 1

[0052] A system for resource-based and combined treatment of waste liquid from the carbon fiber industry, such as Figure 1 As shown, it includes a spinning dilute solvent pretreatment unit and a return solution pre-separation unit;

[0053] The spinning dilute solvent pretreatment unit includes a decontamination tower TⅠ1, a primary dehydration tower TⅡ2, a secondary dehydration tower TⅢ3 and a tertiary dehydration tower TⅣ4 in sequence according to the flow direction of the tower bottom material;

[0054] The return single solution pre-separation unit includes a pretreatment tower TVII12; the top of the pretreatment tower TVII12 leads to the acrylonitrile refining tower TVIII13; the top of the acrylonitrile refining tower TVIII13 leads to the pretreatment tower TVII12;

[0055] The bottom of the tertiary dehydration tower TIV4 and the bottom of the pretreatment tower TVII12 are both connected to the core dehydration device 5, the discharge port of the core dehydration device 5 is connected to the deep dehydration tower TV6, and the bottom of the deep dehydration tower TV6 is connected to the DMSO refining tower TVI7;

[0056] The decontamination tower TⅠ1, the primary dehydration tower TⅡ2, the secondary dehydration tower TⅢ3, the tertiary dehydration tower TⅣ4, the deep dehydration tower TⅤ6, the DMSO refining tower TⅥ7, the pretreatment tower TⅦ12 and the acrylonitrile refining tower TⅧ13 are all distillation towers;

[0057] The decontamination tower TⅠ1 is used to remove water containing light components;

[0058] The core residue removal device 5 is a de-heaving device for removing heavy components;

[0059] The pretreatment tower TVII12 is used to pre-separate DMSO and acrylonitrile;

[0060] The top outlet of the decontamination tower TⅠ1 leads to the wastewater tank 9; the wastewater tank 9 leads to the biochemical treatment system 11;

[0061] The top water outlets of the first dehydration tower TⅡ2, the second dehydration tower TⅢ3 and the third dehydration tower TⅣ4 all lead to the process water tank 8; the top water outlet of the deep dehydration tower TⅤ6 leads to the process water tank 8; the process water tank 8 leads to the carbon fiber spinning system 15;

[0062] The system for resource-based combined treatment of waste liquid in the carbon fiber industry also includes a dilute solvent wastewater raw material tank 10, which leads to a decontamination tower TⅠ1;

[0063] The system for resource-based combined treatment of waste liquid from the carbon fiber industry also includes a return single solution mother liquid tank 11, which leads to a pretreatment tower TⅦ12;

[0064] The top steam outlets of the decontamination tower TⅠ1, the first-stage dehydration tower TⅡ2, and the second-stage dehydration tower TⅢ3 are all connected to the next-stage distillation tower;

[0065] The top steam outlet of the DMSO refining tower TVI7 leads to the core desulfurization device 5.

[0066] The above-mentioned system for resource-based combined treatment of carbon fiber industry waste liquid is used to resource-based combined treatment of carbon fiber industry waste liquid, wherein the carbon fiber industry waste liquid includes a spinning dilute solvent and a return single solution; wherein, in the carbon fiber industry waste liquid: the DMSO content is 15.1wt%; wherein, in the return single solution: the acrylonitrile content is 6.2wt%, the DMSO content is 92wt%, and the water content is 1.8wt%.

[0067] The specific steps are as follows:

[0068] S1. Carbon fiber spinning dilute solvent treatment:

[0069] The spinning dilute solvent enters the dilute solvent wastewater raw material tank 10, and the spinning dilute solvent in the dilute solvent wastewater raw material tank 10 is fed from the decontamination tower TⅠ1. After distillation, the wastewater containing impurities is discharged from the top outlet of the tower and input into the wastewater tank 9. The wastewater in the wastewater tank 9 is transported to the biochemical treatment system 11 for further biochemical treatment; the bottom liquid of the decontamination tower TⅠ1 enters the primary dehydration tower TⅡ2, the secondary dehydration tower TⅢ3 and the tertiary dehydration tower TⅣ4 in turn for distillation and dehydration. The water removed from the primary dehydration tower TⅡ2, the secondary dehydration tower TⅢ3 and the tertiary dehydration tower TⅣ4 is extracted from the top outlet of the tower and input into the process water tank 8, and then transported to the process water tank 8. The water is sent to the carbon fiber spinning system 15 as process water; the bottom liquid of the tertiary dehydration tower TIV4 is transported to the core dehydration device 5 to remove heavy components, and the removed residual liquid (heavy boiling material) is discharged as hazardous waste; the liquid after dehydration is transported to the deep dehydration tower TV6 for deep distillation and dehydration; the bottom material of the deep dehydration tower TV6 enters the DMSO refining tower TVI7 for refining, and the DMSO product is obtained at the top of the tower, and the heavy boiling material of the bottom of the tower is discharged; the water removed from the deep dehydration tower TV6 has no intermediate impurities, is extracted from the top of the tower and input into the process water tank 8, and then transported to the carbon fiber spinning system 15 as process water;

[0070] The operating pressures of the decontamination tower TⅠ1, the primary dehydration tower TⅡ2, the secondary dehydration tower TⅢ3, and the tertiary dehydration tower TⅣ4 are sequentially reduced, using a downstream coupling process. Specifically, the steam generated at the top of the decontamination tower TⅠ1 heats the kettle of the primary dehydration tower TⅡ2; the steam generated at the top of the primary dehydration tower TⅡ2 heats the kettle of the secondary dehydration tower TⅢ3; and the steam generated at the top of the secondary dehydration tower TⅢ3 heats the kettle of the tertiary dehydration tower TⅣ4. The steam generated at the top of the DMSO refining tower TⅥ7 heats the core dehydration device 5.

[0071] Among them: the top temperature of the decontamination tower TⅠ1 is 129℃, and the bottom temperature is 130℃; the top temperature of the first-stage dehydration tower TⅡ2 is 124℃, and the bottom temperature is 125℃; the top temperature of the second-stage dehydration tower TⅢ3 is 117℃, and the bottom temperature is 119℃; the top temperature of the tertiary dehydration tower TⅣ4 is 60℃, and the bottom temperature is 110℃; the top temperature of the deep dehydration tower TⅤ6 is 55℃, and the bottom temperature is 130℃; the top temperature of the DMSO refining tower TⅥ7 is 128℃, and the bottom temperature is 130℃.

[0072] S2. Carbon fiber polymerization section return single solution treatment:

[0073] The return single solution enters the return single solution mother liquor tank 11, and the return single solution in the return single solution mother liquor tank 11 enters the pretreatment tower TⅦ12 for distillation and pre-separation, and the crude DMSO product is obtained in the tower bottom, and the crude acrylonitrile product is obtained at the tower top; the crude DMSO product enters the core decomposition device 5, and is removed together with the material in the tower bottom of the tertiary dehydration tower TⅣ4 in step S1 to remove the heavy components, and then is deeply dehydrated and refined together; the crude acrylonitrile product enters the acrylonitrile refining tower TⅧ13 for refining, and the acrylonitrile product is obtained in the tower bottom, and the acrylonitrile product is recycled to the carbon fiber polymerization system 16; the material at the top of the acrylonitrile refining tower TⅧ13 returns to the pretreatment tower TⅦ12 for further treatment.

[0074] Among them: the top temperature of the pretreatment tower TⅦ12 is 50°C, the bottom temperature is 130°C, and the operating pressure is 40kPa; the top temperature of the acrylonitrile refining tower TⅧ13 is 50°C, the bottom temperature is 60°C, and the operating pressure is 40kPa.

[0075] The product indicators obtained by the above method are shown in Table 1:

[0076] Table 1 Example 1 Resource-based combined treatment of carbon fiber industry waste liquid to obtain product purity

[0077] product DMSO Acrylonitrile process water purity 99.997％ 99.65％ 99.996％

[0078] Example 2

[0079] A system for resource-based and combined treatment of waste liquid from the carbon fiber industry, such as Figure 2 As shown, referring to Example 1, the difference from Example 1 is:

[0080] The spinning dilute solvent pretreatment unit includes a first-level dehydration tower Tα17 and a second-level dehydration tower Tβ18 in sequence according to the flow direction of the material in the tower bottom; the tops of the first-level dehydration tower Tα17 and the second-level dehydration tower Tβ18 are both connected to steam compressors, which pressurize the steam at the top of the tower and then couple themselves; specifically, the top of the first-level dehydration tower Tα17 is connected to two parallel first-level steam compressors 19, and the top of the second-level dehydration tower Tβ18 is connected to two groups of parallel second-level steam compressor units 20, and each group of second-level steam compressor units 20 consists of two steam compressors connected in series; the first-level steam compressor 19 is a large-flow, low-pressure ratio compressor, and the steam compressor in the second-level steam compressor unit 20 is a small-flow, high-pressure ratio compressor.

[0081] The top water outlets of the first dehydration tower Tα17 and the second dehydration tower Tβ18 are both connected to the process water tank 8;

[0082] The top water outlet of the deep dehydration tower TV6 can lead to the process water tank 8 and the waste water tank 9 respectively.

[0083] Other technical features are the same as those of the system in Example 1.

[0084] The above-mentioned system for resource-based combined treatment of carbon fiber industry waste liquid is used to resource-based combined treatment of carbon fiber industry waste liquid, wherein the carbon fiber industry waste liquid includes a spinning dilute solvent and a return single solution; wherein, in the carbon fiber industry waste liquid: the DMSO content is 15.1wt%; wherein, in the return single solution: the acrylonitrile content is 6.2wt%, the DMSO content is 92wt%, and the water content is 1.8wt%.

[0085] S1. Carbon fiber spinning dilute solvent treatment:

[0086] The spinning dilute solvent enters the dilute solvent wastewater raw material tank 10, and the spinning dilute solvent in the dilute solvent wastewater raw material tank 10 is fed from the primary dehydration tower Tα17. After distillation and dehydration, the bottom liquid of the primary dehydration tower Tα17 enters the secondary dehydration tower Tβ18 for distillation and dehydration. The water removed from the primary dehydration tower Tα17 and the secondary dehydration tower Tβ18 is extracted from the tower top extraction port and input into the process water tank 8, and then transported to the carbon fiber spinning system 15 as process water; the bottom liquid of the secondary dehydration tower Tβ18 is transported to the nuclear The core dehydration device 5 removes heavy components, and the removed residual liquid (heavy boiling products) is discharged as hazardous waste; the liquid after dehydration is transported to the deep dehydration tower TV6 for deep distillation and dehydration; the bottom material of the deep dehydration tower TV6 enters the DMSO refining tower TVI7 for refining, and the DMSO product is obtained at the top of the tower, and the heavy boiling products in the bottom of the tower are discharged; the water removed from the deep dehydration tower TV6 has no intermediate impurities, and is extracted from the top of the tower and input into the process water tank 8, and then transported to the carbon fiber spinning system 15 as process water;

[0087] The process steam generated at the top of the first-stage dehydration tower Tα17 is pressurized by the first-stage steam compressor 19 and then thermally autocoupled; the process steam generated at the top of the second-stage dehydration tower Tβ18 is pressurized by the second-stage steam compressor unit 20 and then thermally autocoupled; the steam generated at the top of the DMSO refining tower TⅥ7 is used to heat the core deresidue device 5.

[0088] Among them: the top temperature of the first-level dehydration tower Tα17 is 105℃, and the bottom temperature is 110℃; the top temperature of the second-level dehydration tower Tβ18 is 106℃, and the bottom temperature is 130℃; the top temperature of the deep dehydration tower TⅤ6 is 45℃, and the bottom temperature is 129.9℃; the top temperature of the DMSO refining tower TⅥ7 is 129℃, and the bottom temperature is 130℃.

[0089] S2. Carbon fiber polymerization section return single solution treatment:

[0090] The return single solution enters the return single solution mother liquor tank 11, and the return single solution in the return single solution mother liquor tank 11 enters the pretreatment tower TⅦ12 for distillation and pre-separation, and the crude DMSO product is obtained in the tower bottom, and the crude acrylonitrile product is obtained at the tower top; the crude DMSO product enters the core decomposition device 5, and is removed together with the heavy components together with the tower bottom material of the secondary dehydration tower Tβ18 in step S1, and then deeply dehydrated and refined together; the crude acrylonitrile product enters the acrylonitrile refining tower TⅧ13 for refining, and the acrylonitrile product is obtained in the tower bottom, and the acrylonitrile product is recycled to the carbon fiber polymerization system 16; the top material of the acrylonitrile refining tower TⅧ13 returns to the pretreatment tower TⅦ12 for further treatment.

[0091] Among them: the top temperature of the pretreatment tower TⅦ12 is 50°C, the bottom temperature is 130°C, and the operating pressure is 40kPa; the top temperature of the acrylonitrile refining tower TⅧ13 is 50°C, the bottom temperature is 60°C, and the operating pressure is 40kPa.

[0092] The product indicators obtained by the above method are shown in Table 2:

[0093] Table 2 Purity of products obtained from resource-based combined treatment of waste liquid from the carbon fiber industry in Example 2

[0094] product DMSO Acrylonitrile process water purity 99.996％ 99.6％ 99.997％

[0095] Energy consumption of the above method: Taking DMSO as the product, the energy consumption of the spinning dilute solvent recovery line is 1.11 tons of steam / product.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for resource-based combined treatment of wastewater from the carbon fiber industry, characterized in that: It includes a spinning dilute solvent pretreatment unit and a return solution pre-separation unit; The spinning dilute solvent pretreatment unit includes at least one dehydration tower; The return single solution pre-separation unit includes a pretreatment tower TⅦ (12); the top of the pretreatment tower TⅦ (12) leads to an acrylonitrile refining tower TⅧ (13); The bottom of the last stage dehydration tower and the bottom of the pretreatment tower TⅦ (12) are both connected to the core dehydration device (5), the discharge port of the core dehydration device (5) is connected to the deep dehydration tower TⅤ (6), and the bottom of the deep dehydration tower TⅤ (6) is connected to the DMSO refining tower TⅥ (7); The dehydration tower, deep dehydration tower TⅤ (6), DMSO refining tower TⅥ (7), pretreatment tower TⅦ (12) and acrylonitrile refining tower TⅧ (13) are all distillation towers; The core removal device (5) is used to remove heavy components; The pretreatment tower TVII (12) is used for pre-separating DMSO from acrylonitrile.

2. The system for resource-based combined treatment of waste liquid from the carbon fiber industry according to claim 1 is characterized in that: The top of the acrylonitrile refining tower TⅧ (13) leads to the pretreatment tower TⅦ (12).

3. The system for resource-recovery and combined treatment of waste liquid from the carbon fiber industry according to claim 1 or 2, characterized in that: The spinning dilute solvent pretreatment unit includes a decontamination tower TⅠ (1), a primary dehydration tower TⅡ (2), a secondary dehydration tower TⅢ (3) and a tertiary dehydration tower TⅣ (4) in sequence according to the flow direction of the tower bottom material; Wherein, the decontamination tower TI (1) is a distillation tower for removing water containing light components.

4. The system for resource-recovery and combined treatment of waste liquid from the carbon fiber industry according to claim 3 is characterized in that: The top steam outlets of the decontamination tower TI (1), the first-stage dehydration tower TII (2), and the second-stage dehydration tower TIII (3) all lead to the next-stage distillation tower.

5. The system for resource-recovery and combined treatment of waste liquid from the carbon fiber industry according to claim 1 or 2, characterized in that: The spinning dilute solvent pretreatment unit includes a primary dehydration tower Tα (17) and a secondary dehydration tower Tβ (18) in sequence according to the flow direction of the tower bottom material; the tops of the primary dehydration tower Tα (17) and the secondary dehydration tower Tβ (18) are both connected to steam compressors, which pressurize the steam at the top of the towers and then couple themselves.

6. The system for resource-recovery and combined treatment of waste liquid from the carbon fiber industry according to claim 5 is characterized in that: The top of the first-stage dehydration tower Tα (17) is connected to two parallel steam compressors, and the top of the second-stage dehydration tower Tβ (18) is connected to two parallel steam compressor groups, wherein the steam compressor groups are several steam compressors connected in series.

7. The system for resource-recovery and combined treatment of waste liquid from the carbon fiber industry according to claim 1 or 2, characterized in that: The top steam outlet of the DMSO refining tower TVI (7) leads to the core decontamination device (5).

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