Method for completely removing acidic substances in crude vinyl chloride gas

Abstract

The invention relates to a method for completely removing acidic substances in crude vinyl chloride gas. A device comprises two parts including hydrogen chloride absorption and double-tower alkali washing; a technological flow comprises the following steps: conveying the crude vinyl chloride gas into a hydrogen chloride combined absorption tower; carrying out two grades of absorption through dilute hydrochloric acid and concentrated hydrochloric acid respectively, and then conveying the crude vinyl chloride gas into a dilute hydrochloric acid tower to finish whole absorption of hydrogen chloride in the dilute hydrochloric acid tower; conveying the crude vinyl chloride gas ejected out from the dilute hydrochloric acid tower into an alkali washing tower I; washing the crude vinyl chloride gas by utilizing alkali liquid in the alkali washing tower I; then conveying the crude vinyl chloride gas into an alkali washing tower II; then washing the crude vinyl chloride gas by utilizing high-concentration alkali liquid so as to ensure that the acidic substances in the crude vinyl chloride gas are completely removed. According to the method provided by the invention, the acidic substances inthe crude vinyl chloride gas from a converter can be completely absorbed to form hydrochloric acid with the concentration of 29 to 31 weight percent, so that the loss of the vinyl chloride is reducedand damages to subsequent treatment equipment are reduced; the consumption of alkali and fresh water can be reduced through two-grade alkali washing, the amount of discharged wastewater can also be reduced and pollution to the environment is extremely alleviated.

Description

Technical field: [0001] The invention relates to a method for removing acidic substances in mixed gas produced by calcium carbide acetylene hydrochlorination, in particular to a method for completely removing acidic substances in crude vinyl chloride gas, belonging to the technical field of gas purification. Background technique: [0002] Polyvinyl chloride (PVC) has excellent comprehensive properties and is one of the five general-purpose synthetic resins, widely used in various fields of the national economy. In the past 10 years, my country's PVC production capacity has increased rapidly, and by the end of 2012, the production capacity had reached 24 million tons, accounting for about half of the world's total production capacity. In view of the resource characteristics of rich coal and poor oil in our country, most domestic PVC manufacturers use the calcium carbide method to produce vinyl chloride. The main reaction is that acetylene and hydrogen chloride are catalyzed b...

AI Technical Summary

Problems solved by technology

[0008] The purpose of the present invention is to overcome the shortcoming of prior art, provide a kind of method of completely removing the acidic substance in the crude vinyl chloride gas, to completely remove acidic substances such as remaining hydrogen chloride and carbon dioxide in the crude vinyl chloride gas that the converter comes out, solve Common problems in PVC production enterprises such as high loss of vinyl chloride VCM, waste of lye, and equipment corrosion

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