Evaporation and recycling process of methanol water solution of sodium chloride

Abstract

The invention relates to an evaporation and recycling process of a methanol water solution of sodium chloride. The evaporation and recycling process sequentially comprises the following steps: (1) pre-heating a new raw solution for raising the temperature; (2) heating and evaporating the raw solution by utilizing fresh steam in a single-effect falling-film evaporator to form a single-effect concentrated solution, and evaporating methanol and moisture to generate single-effect steam; (3) in a double-effect falling-film evaporator, heating and evaporating the single-effect steam by utilizing the single-effect concentrated solution to obtain a double-effect concentrated solution, and generating double-effect steam; (4) in a three-effect forced circulating evaporation and crystallization unit, heating the double-effect concentrated solution by utilizing the double-effect steam to form three-effect crystal slurry, and generating three-effect steam; (5) enabling the three-effect crystal slurry to enter a three-effect hydrocyclone for concentrating and thickening, returning a light phase back to the three-effect forced circulating evaporation and crystallization unit for circulating, and conveying a heavy phase into a thick tank for concentrating and thickening; and (6) conveying the heavy phase of the thick tank into a centrifuge for separating, discharging sodium chloride crystals from a solid-phase outlet of the centrifuge, and conveying a mother solution into a mother solution tank. The process is low in energy consumption and can realize complete recycling of sodium chloride and methanol.

Description

technical field [0001] The invention relates to a methanol aqueous solution evaporation recovery process of sodium chloride, which can be applied to the treatment of methanol aqueous solution with high sodium chloride in the environmental protection industry and the recovery of methanol in the food and pharmaceutical industry, and belongs to the technical field of industrial water treatment. Background technique [0002] In the environmental protection and pharmaceutical industries, due to the diversity of the chemical industry, the solution components are becoming more and more complex, mostly with high salt content and high organic matter. The methanol aqueous solution of sodium chloride is usually recovered by rectification process. After separation by rectification, Methanol overflows, and sodium chloride remains in the tower kettle, and the tower kettle needs to be regularly drained. A part of methanol will be entrained in the raffinate, causing losses and reducing the ...

AI Technical Summary

Problems solved by technology

A part of methanol will be entrained in the raffinate, causing loss and reducing the recovery rate of methanol; at the same time, sodium chloride is not recycled, which increases the burden of subsequent treatment

In addition, distillation in the tower still requires a large amount of steam and high energy consumption

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