Separation equipment and separation process for HF (Hydrogen Fluoride) in difluoromethane reaction gas

Abstract

The invention discloses separation equipment for HF (Hydrogen Fluoride) in a difluoromethane reaction gas. The equipment comprises an HF absorption tower, a falling film absorber, a water scrubber, an alkali scrubber and circulating pumps arranged on the water scrubber and the alkali scrubber. The invention further discloses a separation process for HF in the difluoromethane reaction gas. The separation process comprises the following steps: introducing the difluoromethane reaction gas which flows through a reflux tower into the HF absorption tower, feeding 98wt% concentrated sulfuric acid in an elevated tank through the tower top of the HF absorption tower, and feeding a mixed gas absorbed by the HF absorption tower into the falling film absorber; then feeding the mixed gas into the water scrubber, circulating until the hydrochloric acid concentration is about 32%, and collecting; and recycling concentrated sulfuric acid in a tower kettle of the HF absorption tower to an anhydrous hydrogen fluoride production device. The HF absorption tower for removing HF is simple in structure, operates at a normal temperature and pressure, and is low in energy consumption; concentrated sulfuric acid, which contains a certain amount of HF and is obtained by the HF absorption tower, is fed into the anhydrous hydrogen fluoride production device so as to be reused, so that wastes of raw materials are reduced; the hydrochloric acid obtained by the process is high in quality, the fluorine ion content is not more than 50ppm, and the environment pollution is reduced.

Description

Technical field [0001] The invention relates to a separation equipment for HF in difluoromethane reaction gas. [0002] The invention also relates to a HF separation process, in particular to a method for separating HF contained in the reaction gas during the process of preparing difluoromethane by dichloromethane fluorination to obtain high-quality difluoromethane and hydrochloric acid. Background technique [0003] Difluoromethane production uses dichloromethane and hydrogen fluoride as raw materials, and is prepared by fluorination catalytic reaction in a reactor, and at the same time produces a large amount of hydrogen chloride by-products. 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, the reaction product is washed with water and alkali eluted to remove hydrogen chloride, and then dehydrated and rectified to obtain high-purity difluoromethane. However, in the ...

AI Technical Summary

Problems solved by technology

However, in the reaction gas, due to the azeotrope of difluoromethane and hydrogen fluoride, the reaction gas inevitably brings out a part of hydrogen fluoride, accounting for 2-3% (wt), so the hydrochloric acid obtained by washing contains more fluorine ions and becomes waste acid

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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