Method for realizing hydrochloric acid closed cycle and precluding mercury pollution in polychloroethylene production

Abstract

The invention discloses a method for realizing a closed circuit of hydrogen hydride and hydrochloric acid in the polyvinyl chloride production to eliminate mercury pollution. The method is capable of maintaining the water balance of a hydrogen chloride absorption and desorption system to avoid hydrochloric acid containing mercury from being expelled from the system. The hydrogen chloride absorption process which is a process of low temperature absorption by section respectively adopts cycling hydrochloric acid and process water to wash process gas containing the hydrogen chloride. The desorption is carried out through single-section tower type desorption indirect heating; and the desorbed hydrogen chloride returns to a vinyl chloride synthesization system, and the thin hydrochloric acid returns to an absorption system. Therefore, the consumption of the hydrogen chloride can be reduced, the acidic water pollution caused by the hydrogen chloride can be avoided, and the environmental pollution caused by the mercury can be eliminated. Mercury-free condensed hydrochloric acid produced by a condenser arranged at a gas outlet of a desorption tower can be sold as byproduct hydrochloric acid.

Description

Technical field [0001] The present invention relates to the polyvinyl chloride industry in the chemical industry. The invention is a method for realizing the closed circulation of hydrogen chloride and hydrochloric acid in the production of polyvinyl chloride to prevent mercury pollution. The invention can effectively maintain the hydrogen chloride absorption and desorption system in operation The water balance can prevent mercury-containing hydrochloric acid from being discharged from the system, and can effectively recover excess hydrogen chloride in the synthesis process of vinyl chloride monomer, so that it can be returned to the process system to reduce hydrogen chloride consumption, avoid acidic water pollution caused by hydrogen chloride, and especially eliminate chlorine Reduce the pollution caused by mercury to the environment, and realize the recycling and recycling of polluted substances. Background technique [0002] At present, the calcium carbide method is wide...

AI Technical Summary

Problems solved by technology

[0003] In the existing vinyl chloride production plant, there are following technological defects: in order to remove excessive hydrogen chloride in the crude vinyl chloride, in production practice, the single-stage absorption process that all adopts, the first method is to adopt foam pickling tower, this The method is an adiabatic absorption process, and the heat of dissolution of hydrogen chloride cannot be discharged from the absorption system in time, so that the operating temperature of the foam pickling tower system rises and the process conditions for hydrogen chloride absorption deteriorate.

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