Recycling method of waste solvent in automobile industry

Abstract

The invention belongs to the technical field of solvent recycling, and particularly discloses a method for recycling an automobile industry waste solvent. The method comprises the following steps: (1)simple distillation: distilling the waste solvent by adopting a distilling apparatus, and obtaining liquid comprising xylene and n-butyl acetate; (2) magnetization: pumping the liquid obtained in step (1) into a closed magnetizing tube to be circularly magnetized; (3) extraction rectification: extracting the liquid treated in the step (2) by using N-methyl pyrrolidone as an extraction agent by virtue of an extraction rectification tower with 40 to 80 theoretical tower plates, and obtaining an xylene solution and a residual solution; and (4) intermittent rectification: treating the residual solution in an intermittent rectification manner, wherein the rectification parameters are set as follows: the consumption of cooling circulating water: 48 to 60 m<3> / h; the steam pressure: 0.5 to 0.7 MPa; the steam consumption: 0.3 to 0.5 t / h; and power load of the apparatus: 45 to 50 KW. By adopting the method, the waste solvent can be distilled for multiple times, and the waste solvent can be effectively recycled.

Description

technical field [0001] The invention belongs to the technical field of solvent recovery, and in particular relates to a method for recovering waste solvent in the automobile industry. Background technique [0002] There are many parts in the automobile manufacturing process that need to be painted, and some waste solvents will be produced during the painting operation, such as gun cleaning water, banana water, thinner and other organic solvents produced by cleaning spray guns. These used organic solvents have many kinds of organic impurities, and the purity is reduced. Generally, they are sold as waste oil, or processed by "dilution method", "incineration method" and "vacuum distillation method". Waste solvents are not allowed to be discharged directly and must be treated, because most of the waste organic solvents are highly toxic, flammable, explosive, corrosive, volatile or reactive, and are extremely harmful to the environment and human health. Classified as a Class I h...

AI Technical Summary

Problems solved by technology

[0003] The current conventional treatment method is to use distillation to recover solvents, but the waste solvents in the automotive industry contain resins, solid particles, etc. As the concentration of solids increases during distillation, the viscosity increases, and continued distillation will become gelatinous. Distillation cannot continue and it is very difficult to discharge the residue from the device

These waste solvents cannot be completely recovered by conventional methods, and the distillation residues have to be incinerated as waste oil. During the incineration process, a large amount of carbon dioxide and smoke are emitted into the atmosphere, which not only wastes petroleum resources but also pollutes the environment.

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