Low-concentration dimethylformamide wastewater recovery system and method

Abstract

The invention discloses a low-concentration dimethylformamide wastewater recovery system and method. The system comprises a refining tower, an impurity removal tower, a raw material preheater and a feeding preheater, the refining tower is provided with an intermediate boiler, a refining tower reboiler, a compressor, a refining tower condenser, a refining tower reflux tank and a reflux pump; and the impurity removal tower is provided with an impurity removal tower reboiler, an impurity removal tower condenser and an impurity removal tower reflux tank. The method disclosed by the invention is energy-saving, free of secondary pollution, capable of removing DMF decomposition impurity dimethylamine, and suitable for recycling and reusing low-concentration DMF wastewater in membrane production.According to the method, the 90wt% discharge amount of DMF wastewater in the membrane production process can be reduced, and the content of dimethylamine in the recycled water is lower than 20ppm. TheDMF recovery rate is greater than 99wt%, the purity of the recovered DMF is greater than or equal to 99.5 wt%, the requirements of national standard DMF industrial solvents in China are met, the equipment investment is less, and meanwhile, the energy-saving requirement is met.

Description

technical field [0001] The invention relates to the technical field of waste water recovery and treatment, in particular to a low-concentration dimethylformamide waste water recovery system and method. Background technique [0002] A relatively advanced production process in membrane production is a wet process in which DMF is used as a solvent. During the production process, a large amount of DMF is used, and a large amount of low-concentration DMF-containing wastewater is produced in the later stage. DMF has a high market price and is toxic, so it needs to be treated in an environmentally friendly manner. In order to meet the economic and social benefits of the enterprise, it is necessary to develop an efficient low-concentration DMF wastewater recovery and wastewater reuse process, recycle DMF in the wastewater, remove impurities generated during the recovery process, make the wastewater meet the reuse requirements, and at the same time realize the recycling of industrial...

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Problems solved by technology

However, the extractant will cause secondary pollution to the water phase, and the recovered water cannot be reused in the membrane production process, which is not suitable for the production and application of nanofiltration membranes.

[0005] Due to the lack of impurity removal equipment, the currently implemented industrial DMF wastewater recovery technology without secondary pollution has a high content of DMF decomposition product dimethylamine in water. At the same time, it adopts multi-tower separation, which requires high equipment investment and energy consumption, and is not suitable for nanofiltration membranes. Recovery and reuse of DMF wastewater in production

At present, the DMF wastewater of the nanofiltration membrane production unit is directly treated as industrial sewage, without recycling and reuse

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