A solvent recovery system for dmf salty wastewater

Abstract

The invention discloses a solvent recovering system for DMF (Dimethyl Formamide) saliferous wastewater. An evaporating and rectifying system is formed through combining a plurality of evaporators and rectifying towers, and a reboiler, a cooling system, a reflux system, a negative pressure system and a salt yielding system are disposed correspondingly; the recovering system disclosed by the invention is adopted to treat the DMF saliferous wastewater; top steam of the rectifying tower of a corresponding previous effect serves as a heat source of the evaporator of the rectifying tower of a corresponding next effect through setting the operating pressure of the rectifying tower of each effect, so as to use the condensation heat energy of steam of the corresponding previous effect; and the system disclosed by the invention combines the evaporators and the rectifying towers, so that the problem of tower blockage during the rectification of the DMF saliferous wastewater can be solved, the process is simple, the energy consumption is low, and high-purity salt and a DMF product can be obtained. The volume of steam consumed by the solvent recovering system for the DMF saliferous wastewater, disclosed by the invention, is 40-65% that of steam consumed during ordinary single-tower rectification.

Description

technical field [0001] The invention relates to a solvent recovery system for DMF salty wastewater. Background technique [0002] DMF, also known as N,N-dimethylformamide, is a colorless and transparent liquid that is miscible with water, alcohols, esters, ketones, ethers, unsaturated hydrocarbons and aromatic hydrocarbons, and is called a "universal solvent". , Widely used in petrochemical, organic synthesis, pharmaceutical, artificial leather and other fields, so a large amount of DMF wastewater will be produced in the chemical production process. At present, in industrial production, rectification is often used for high-concentration DMF wastewater, and multi-effect distillation is often used for low-concentration DMF wastewater. DMF is easily decomposed into formic acid and dimethylamine when heated under acidic or alkaline conditions. The existence of formic acid and dimethylamine will seriously affect the quality of DMF products and cause serious corrosion to equipmen...

AI Technical Summary

Problems solved by technology

DMF is easily decomposed into formic acid and dimethylamine when heated under acidic or alkaline conditions. The existence of formic acid and dimethylamine will seriously affect the quality of DMF products and cause serious corrosion to equipment

Therefore, before treating DMF wastewater, acid or alkali is often used to neutralize DMF wastewater into neutrality, and then follow-up treatment will produce salt during the neutralization process. For the treatment of low-concentration salt-containing DMF wastewater, rectification is used. method can lead to problems such as distillation column blockage

[0003] Patent CN200510061857.5 discloses a three-effect recovery method containing DMF wastewater, and patent CN201310304564.X discloses a four-effect rectification recovery method containing DMF wastewater. Although these methods greatly save the recovery energy consumption of DMF wastewater, but The tower plugging problem of salt in DMF wastewater is not considered

Patent CN200820120577.6 discloses a treatment device before rectification of DMF recovered liquid, and patent CN201320014613.1 discloses a DMF wastewater recovery residue evaporator. These patents consider the problem of tower blockage of salt in DMF wastewater, but the pretreatment And the post-processing process is cumbersome, and the investment and energy consumption of industrial equipment are relatively large

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