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Adding salt intermittent extraction rectification separation method of acetonitrile-water azeotropic mixture

A technology of extractive distillation and extractive distillation column, which is applied in the field of separation of acetonitrile-water azeotropic mixture, can solve the problems that have not been found in the data, and achieve the effect of flexible operation and low equipment investment

Inactive Publication Date: 2008-09-03
TIANJIN UNIV
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

There are many articles and patents related to the separation of the mixture, and there is no published information on the separation of acetonitrile-water azeotropic system plus salt extraction rectification

Method used

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  • Adding salt intermittent extraction rectification separation method of acetonitrile-water azeotropic mixture

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Embodiment 1

[0010] A batch extraction and rectification device is adopted, in which the diameter of the extraction and rectification tower is φ40mm, and theta mesh ring packing is installed inside. Drop into 500ml acetonitrile-water mixture (wherein acetonitrile 80%, water 20%, all are mass percentages) in heating kettle, the selected mixed extractant of test is the ethylene glycol solution of calcium chloride (containing calcium chloride 10%), open Heating the heat source of the kettle and the cold source of the condenser, the extractive distillation tower starts to run. When the rising steam in the extractive distillation tower rises to the extractant inlet, the extractant is added into the extractive distillation tower from the extractant inlet, and the extraction agent is controlled. The speed is 600ml / h, total reflux operation, when the temperature of the top of the extractive distillation column is 81.5-82°C, the acetonitrile content in the fraction is ≥99% and starts to discharge, t...

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Abstract

The invention provides a method of batch extractive distillation with salt for separating an acetonitrile-water azeotropic mixture. The method adopts the rectification column of an extractive distillation column, the rectification column has batch operation, glycol solution which contains calcium chloride is taken as extraction solvent, under the normal pressure, the infinite branch reflux operation is firstly carried out, then acetonitrile products, acetonitrile-water transition section fraction and dehydration are orderly withdrawn from the extractive distillation column under the operation conditions of different temperatures and reflux ratios, and then water-glycol transition section fraction is withdrawn under the decompression condition, finally, the glycol extraction solvent which contains the calcium chloride and is stored in a heating pot is pumped into an extraction solvent storage tank, and a new batch acetonitrile-water mixture as well as the acetonitrile-water transition section fraction and the water-glycol transition section fraction are loaded into the heating pot for carrying out the next batch extractive distillation and separation. The method has the advantages that the adopted extraction solvent destroys the acetonitrile-water azeotropic system, the acetonitrile products with high purity can be separated out, the single-tower operation is adopted, the operation is flexible, and the expenditure and the investment of the equipment are less.

Description

technical field [0001] The invention relates to a method for separating acetonitrile-water azeotropic mixture by intermittent extraction and rectification by adding salt, which belongs to the separation technology of acetonitrile-water azeotropic mixture. Background technique [0002] Extractive distillation with salt addition is a special distillation separation technology, which dissolves salt into a solvent to form a mixed extraction agent, which is suitable for the separation of azeotropic systems. The purpose of separation is achieved by continuously adding this mixed extractant to the top of the rectification tower to change the relative volatility between the original components. Salt-added extractive distillation combines the advantages of dissolved salt distillation and extractive distillation. It utilizes the salting-out effect to improve the solvent effect, reduce the solvent ratio, and keep the extractant easy to circulate and recover, which is convenient for ind...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D3/40C07C253/34C07C255/03
Inventor 崔现宝冯天扬张缨杨志才李扬
Owner TIANJIN UNIV