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CN-121990945-A - Recycling process of carbon fiber production waste liquid

CN121990945ACN 121990945 ACN121990945 ACN 121990945ACN-121990945-A

Abstract

The invention discloses a recycling process of waste liquid in carbon fiber production, which comprises (1) inputting waste liquid containing acrylonitrile and dimethyl sulfoxide into an acrylonitrile recovery tower, controlling pressure and temperature, separating the acrylonitrile and part of water from gas phase to tower top, wherein the bottom of the acrylonitrile recovery tower is dimethyl sulfoxide and water, (2) sequentially feeding the dimethyl sulfoxide and water at the bottom of the acrylonitrile recovery tower into a first-stage dehydration tower, a second-stage dehydration tower and a third-stage dehydration tower, discharging water from the top of the dehydration tower, purifying the dimethyl sulfoxide at the bottom of the tower step by step until the concentration reaches more than 99.5%, and (3) feeding the purified dimethyl sulfoxide into a rectifying tower, controlling pressure and temperature, feeding the dimethyl sulfoxide impurity at the bottom of the tower, discharging the dimethyl sulfoxide from the gas phase through the tower top, and obtaining pure dimethyl sulfoxide without impurities after condensation recovery. The process is efficient, environment-friendly, energy-saving and high in recovery rate of acrylonitrile and dimethyl sulfoxide.

Inventors

  • Cao Ranxi
  • SU HENGYUAN
  • GUAN FENG
  • SHI RONGBIN
  • DONG JIANYING
  • WANG YU
  • CHEN HAO
  • LI KAI
  • JIANG BO
  • WU XUEFENG
  • WANG WEI
  • WANG LICHEN
  • WANG PENG
  • XIAO JIAN

Assignees

  • 吉林碳谷碳纤维股份有限公司
  • 吉林化纤集团有限责任公司

Dates

Publication Date
20260508
Application Date
20241104

Claims (10)

  1. 1. The recycling process of the carbon fiber production waste liquid is characterized by comprising the following steps of: (1) Inputting waste liquid containing acrylonitrile and dimethyl sulfoxide into an acrylonitrile recovery tower, controlling the pressure and the temperature, separating the acrylonitrile and part of water from gas phase to the tower top, wherein the bottom of the tower is dimethyl sulfoxide and water; (2) The dimethyl sulfoxide and water at the bottom of the acrylonitrile recovery tower sequentially enter a first-stage dehydration tower, a second-stage dehydration tower and a third-stage dehydration tower, the water is discharged from the top of the dehydration tower, and the dimethyl sulfoxide at the bottom of the acrylonitrile recovery tower is purified step by step; (3) And (3) the purified dimethyl sulfoxide enters a rectifying tower, the pressure and the temperature are controlled, the dimethyl sulfoxide impurity is arranged at the bottom of the rectifying tower, the dimethyl sulfoxide forms a gas phase and is discharged through the top of the rectifying tower, and the pure dimethyl sulfoxide without the impurity is obtained after condensation and recovery.
  2. 2. The recycling process of carbon fiber production waste liquid according to claim 1, wherein in the step (1), the control pressure in the acrylonitrile recovery tower is-80 to-95 KPa, the temperature of the top of the tower is 40 ℃ to 50 ℃, the reflux temperature is 50 ℃ to 60 ℃, and the reflux ratio is 0.8 to 1.5.
  3. 3. The process for recycling waste liquid from carbon fiber production according to claim 1 or 2, wherein in the step (1), acrylonitrile and part of water form a gas phase to the top of the tower, are cooled into liquid, overflow into a layering device for layering, and the upper layer is acrylonitrile, and the lower layer is water, and then are recycled respectively.
  4. 4. The process for recycling waste liquid from carbon fiber production according to any one of claims 1 to 3, characterized in that in step (2), normal pressure operation is performed in the primary dehydration tower, the pressure is 1 to 20kpa, the temperature at the top of the tower is 88 to 98 ℃, the temperature at the bottom of the tower is 90 to 100 ℃, and the reflux ratio is 1 to 1.5; preferably, after the first-stage dehydration tower is used for purification, the concentration of dimethyl sulfoxide at the bottom of the tower reaches more than 40 percent.
  5. 5. The recycling process of carbon fiber production waste liquid according to any one of claims 1 to 4, wherein in the step (2), the pressure in the secondary dehydration tower is reduced, the pressure is-90 Kpa to-100 Kpa, the temperature at the top of the tower is 55 ℃ to 65 ℃, the temperature at the bottom of the tower is 65 ℃ to 70 ℃, and the reflux ratio is 0.8 to 1.3; preferably, after the purification by the secondary dehydration tower, the concentration of the dimethyl sulfoxide at the bottom of the tower reaches 65-75 percent.
  6. 6. The recycling process of carbon fiber production waste liquid according to any one of claims 1 to 5, wherein in the step (2), materials enter a first-stage dehydration tower after being preheated by a preheater, a heat source of the preheater is from steam condensate of a bottom heat exchanger, and a gas phase at the top of the first-stage dehydration tower flows through a reboiler of a second-stage dehydration tower to heat kettle liquid of the second-stage dehydration tower.
  7. 7. The recycling process of carbon fiber production waste liquid according to any one of claims 1 to 6, characterized in that in the step (2), the decompression operation is performed in a three-stage dehydration tower, the pressure is-90 Kpa to-100 Kpa, the temperature at the top of the tower is 40 ℃ to 50 ℃, the temperature at the bottom of the tower is 110 ℃ to 120 ℃, the reflux ratio is 0.8 to 1.3, and preferably, the concentration of dimethyl sulfoxide at the bottom of the tower reaches more than 99.5% after the purification by the three-stage dehydration tower.
  8. 8. The recycling process of carbon fiber production waste liquid according to any one of claims 1 to 7, wherein in the step (3), the pressure in the rectifying tower is reduced, the pressure is-90 Kpa to-100 Kpa, the temperature at the top of the tower is 90 ℃ to 100 ℃, and the temperature at the bottom of the tower is 99 ℃ to 105 ℃; preferably, after purification by a rectifying tower, the concentration of dimethyl sulfoxide reaches more than 99.97 percent.
  9. 9. The process for recycling waste liquid in carbon fiber production according to any one of claims 1 to 8, wherein in the step (1), the content of dimethyl sulfoxide in the waste liquid containing acrylonitrile and dimethyl sulfoxide is 10% -40%, and the content of acrylonitrile is 1% -2%.
  10. 10. The process for recycling waste liquid from carbon fiber production according to any one of claims 1 to 9, wherein the content of dimethyl sulfoxide in the sewage discharged from the recycling process is 100ppm or less and the content of acrylonitrile is 0ppm or less.

Description

Recycling process of carbon fiber production waste liquid Technical Field The invention belongs to the field of fiber waste liquid recovery, and particularly relates to a recovery and utilization process of carbon fiber production waste liquid. Background The carbon fiber is a high-performance fiber with high strength and high modulus, the density is less than 1/4 of that of steel, the strength is 7-9 times that of steel, and the carbon fiber also has excellent performances of high temperature resistance, corrosion resistance, friction resistance, electric conduction, heat conduction and the like, and is widely applied to the fields of aerospace, national defense and military industry, new energy, automobile manufacturing, rail transit, medical treatment, sports goods and the like. The Polyacrylonitrile (PAN) -based carbon fiber is a carbon fiber material prepared by polymerizing PAN (AN) serving as a main raw material and then carrying out processes such as spinning, pre-oxidation, carbonization and the like, wherein the yield of the carbon fiber material is more than 90% of the total yield of the carbon fiber. The high-quality and high-performance precursor can be used for preparing the carbon fiber with excellent performance, and the PAN-based carbon fiber precursor preparation process flow mainly comprises two parts of polymerization and spinning. At present, a dimethyl sulfoxide one-step wet spinning process is adopted for preparing the precursor in domestic carbon fiber enterprises. In the production process of polyacrylonitrile carbon fiber precursor, in particular to a one-step production process of dimethyl sulfoxide, and waste liquid generated in the production process contains dimethyl sulfoxide and acrylonitrile. Acrylonitrile is a giant toxic compound, is slightly soluble in water, has extremely toxic effect on microorganisms, is one of high-toxic pollutants in environmental treatment, and is extremely easy to damage human health as well as destroy ecological balance of water. The dimethyl sulfoxide DMSO has stable chemical property and good biological permeability, is a common universal solvent, and has large dosage and easy loss in PAN fiber production. The toxicity of the acrylonitrile on microorganisms and the permeability of the dimethyl sulfoxide lead the organic wastewater produced by the carbon fiber to have large biological toxicity, poor biochemistry and slow degradation speed. And the adopted passive environmental protection treatment technologies such as biochemistry, degradation and the like have the problems of high treatment cost, difficult environmental protection emission and the like. The present invention has been made in view of this. Disclosure of Invention The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a recycling process of waste liquid in carbon fiber production. The recycling process can efficiently recycle the acrylonitrile and the dimethyl sulfoxide in the wastewater produced by the carbon fiber, the recovery rate of the acrylonitrile can reach 99.9 percent, the recovery rate of the dimethyl sulfoxide can reach 99.99 percent, the steam consumption in the whole process is low, the VOCS emission of the production waste gas reaches the national standard, the sewage emission can reach the municipal sewage treatment index requirement, and the recycling of the waste liquid is realized with high efficiency, environmental protection and energy conservation. In order to solve the technical problems, the invention adopts the basic conception of the technical scheme that: The invention provides a recycling process of carbon fiber production waste liquid, which comprises the following steps: (1) Inputting waste liquid containing acrylonitrile and dimethyl sulfoxide into an acrylonitrile recovery tower, controlling the pressure and the temperature, separating the acrylonitrile and part of water from gas phase to the tower top, wherein the bottom of the tower is dimethyl sulfoxide and water; (2) Sequentially feeding dimethyl sulfoxide and water at the bottom of the acrylonitrile recovery tower into a first-stage dehydration tower, a second-stage dehydration tower and a third-stage dehydration tower, discharging water from the top of the dehydration tower, and purifying the dimethyl sulfoxide at the bottom of the tower step by step until the concentration reaches more than 99.5%; (3) And (3) the purified dimethyl sulfoxide enters a rectifying tower, the pressure and the temperature are controlled, the dimethyl sulfoxide impurity is arranged at the bottom of the rectifying tower, the dimethyl sulfoxide forms a gas phase to be discharged through the top of the rectifying tower, and the pure dimethyl sulfoxide without impurity is obtained after condensation and recovery, wherein the purity is 99.97%. The waste liquid containing acrylonitrile and dimethyl sulfoxide mainly originates from recovered polymerization solvent and spi