Method and device for recycling by-product hydrochloric acid in methane fluorine compound production

Abstract

The invention discloses a method for recycling by-product hydrochloric acid in methane fluorine compound production. The method comprises the following steps: step one, extracting HF in mixed gas in fluoridation by using concentrated hydrochloric acid of which the mass concentration is 30 to 35 percent; step two, absorbing HCl in the extracted mixed gas through a falling film absorber, thus preparing the by-product hydrochloric acid; step three, carrying out water washing and alkali washing treatment on residual gas, and entering follow-up equipment, thus obtaining a methane fluorine compound. The method disclosed by the invention can be executed under normal temperature and normal pressure, the energy consumption is small, economy and effectiveness are realized, and the purity of the recycled hydrochloric acid is high.

Description

Technical field [0001] The invention relates to a method and a device for recovering hydrochloric acid, in particular to a method and a device for recovering by-product hydrochloric acid in the production of methane fluoride. Background technique [0002] The production of methane fluorine (fluorochlorine) substitutes generally takes methane chloride and hydrogen fluoride as raw materials, which are prepared through fluorination catalytic reaction in a reactor, and a large amount of hydrogen chloride by-products are produced at the same time. However, a part of hydrogen fluoride easily forms azeotropes with methane fluoride and is taken out of the reactor by the reaction gas. It is difficult to separate HF gas by conventional rectification methods, and it is generally necessary to remove HF gas before rectification. In order to separate the hydrogen chloride in the reaction gas, the current traditional processes at home and abroad mostly use the water washing process, that is, th...

AI Technical Summary

Problems solved by technology

Taking the difluoromethane plant with an annual output of 10,000 tons as an example, 45,000 tons of fluorine-containing hydrochloric acid (including HCL accounting for about 30%) will be produced every year, which will become waste acid because it cannot be used, causing great environmental pollution

At present, there is a relatively advanced dry separation method, that is, the difluoromethane reaction gas first passes through the initial distillation tower to separate hydrogen chloride, and basically does not produce a dilute solution of waste acid containing hydrogen fluoride, but the initial distillation tower increases equipment and energy consumption. Increased production cost of fluoromethane

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