Method for separating and recovery difluorochloromethane azeotropic hexafluoropropene

Abstract

A process for separating and recovering bifluoro-chloromethane-hexafluoropropene azeotrope includes such steps as passing said gas-state mixed azeotrope through gas separating membrane to obtain penetrated bifluoro-chloromethane gas and residual hexafluoropropene gas, condensing the residual gas, rectifying to obtain pure hexafluoropropene, recovering the mixed azeotrope from tower top, returning it along with said penetrated gas back to rectifying system in tetrafluoro ethene production apparatus, and rectifying separation to recover bifluoro-chloromethane.

Description

technical field [0001] The present invention relates to a novel separation and recovery method of difluorochloromethane-hexafluoropropylene azeotrope, more specifically, the preliminary separation of difluorochloromethane-hexafluoropropylene azeotrope through a special high-efficiency gas separation membrane, Destroy its azeotropic ratio, and then use rectification to recover difluorochloromethane (HCFC-22 or F-22) and hexafluoropropylene (HFP) respectively. Background technique [0002] Fluorine is the first element of the VII main group, with the largest electronegativity and small atomic radius. The van der Waals radius is 0.135nm, which is only slightly larger than the hydrogen atom's van der Waals radius of 0.12nm. Most of the hydrogen atoms in organic compounds can be replaced by fluorine atoms with similar volumes to form a large number of organic fluorine compounds. Due to the large electronegativity of fluorine, small atomic radius, low polarizability of fluorine-c...

AI Technical Summary

Problems solved by technology

[0021] 1. The process is complicated, there are many equipments, and the operation is troublesome

[0022] 2. The recovered product has poor purity and needs to be washed with water or absorbed by activated carbon to remove the extractant, resulting in new environmental pollution

[0023] 3. The extraction agent is lost during the operation, the low-priced extraction agent has a small processing capacity, and the high-efficiency extraction agent is expensive, which increases the operating cost

[0024] 4. Both the extractive distillation process and the extraction agent recovery process need to use frozen brine and steam, and the extraction agent needs to be pumped for circulation, which consumes a lot of energy

[0025] 5. The extraction and rectification process is a pressurized operation process. If the extraction agent used is flammable, it is easy to leak and cause a safety accident.

Images