Process for recycling acetonitrile from wastewater by using clapboard tower through azeotropic distillation

Abstract

The invention relates to a process for recycling acetonitrile from wastewater by using a clapboard tower through azeotropic distillation. Trace high boiling point materials of acetonitrile, dichloromethane, silicon ethers and DMF (Dimethyl Formamide) in wastewater are recycled when azeotropic distillation is carried out by using a clapboard tower, continuous feed is carried out at a prefractionation section of the clapboard tower for azeotropic distillation, and overhead fractions enter a phase splitting tank to respectively obtain dichloromethane and water, enter a main tower side-draw of the clapboard tower to obtain acetonitrile, and enter a tower bottom to obtain the high boiling point materials of silicon ethers and the like. Components with higher purity are respectively obtained atthree positions of the tower top, the side-draw and the tower bottom of the clapboard tower in an azeotropic distillation manner by using a single-tower, and continuous production is realized. The process disclosed by the invention is especially suitable for processing low-concentration acetonitrile wastewater (acetonitrile mass concentration is not more than 50 percent); and the process can greatly reduce the energy consumption of the low-concentration acetonitrile wastewater during the treatment while ensuring the acetonitrile yield, and has remarkable practicability and economic benefit.

Description

technical field [0001] The invention relates to a process for recovering acetonitrile from waste water by azeotropic rectification using a partition tower, specifically using a partition tower to recover acetonitrile from waste water containing low-concentration acetonitrile, dichloromethane, DMF and silicon ether and other high-boiling substances. High purity acetonitrile is recovered. Background technique [0002] Wastewater in the chemical industry contains acetonitrile, dichloromethane, water, silicone ether, N, N-dimethylformamide (DMF) and other trace high-boiling substances, which belong to the multivariate azeotropic system and are difficult to separate. The original separation process adopts a multi-tower process, which requires large equipment investment and high energy consumption, and cannot meet the requirements of energy-saving and efficient chemical separation processes. [0003] The clapboard column is a fully thermally coupled rectification column. Its stru...

AI Technical Summary

Problems solved by technology

At present, the industrial wastewater containing acetonitrile is difficult to separate due to the existence of acetonitrile-water completely miscible binary azeotropic system (azeotropic composition 85%, water 15%, V/V, azeotropic point 76°C)

The traditional acetonitri

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