System and method for improving quality of recovered caprolactam and improving recovery process

Abstract

The invention relates to the field of polymerization, in particular to a system and a method for improving the quality of recovered caprolactam and improving a recovery process. The system is additionally arranged on a depolymerization substance evaporation pipeline from a depolymerization tower to a water pre-removal tower, and comprises washing equipment, chemical treatment equipment and filtering separation equipment which are connected in sequence. Depolymers evaporated from the depolymerization tower firstly enter the washing equipment to be washed, cooled and collected, then enter the chemical treatment equipment to be subjected to oxidation-reduction treatment on phosphoric acid and oligomers in washing liquid, finally enter the filtering separation equipment, are subjected to yellow removal, impurity removal and metal ion separation and then return to the water pre-removal tower. According to the invention, phosphoric acid and oligomer are fully solved, waste is turned into wealth, and pipeline equipment of a pre-dehydration and rectification system is not blocked by phosphate and oligomer any more; the quality of the recycled CPL finished product is greatly improved, the index UV value and PN value of the recycled CPL finished product can be greatly improved and become stable, the color is slightly yellow and disappears, the content of impurities and metal ions is greatly reduced, and the pH value becomes more stable and easier to control.

Description

technical field [0001] The invention relates to the field of polymerization, in particular to a system and method for improving the quality of recovered caprolactam and improving the recovery process. Background technique [0002] At present, the extraction water recovery system of the polyamide 6 polymerization plant generally adopts the Gemma recovery process, and the specific process is as follows (such as figure 1 Shown): The extraction water in the polymerization section is collected in the extraction water storage tank 1', and the extraction water in the storage tank (aqueous solution containing 10% caprolactam CPL) is pumped to the three-effect evaporation system 2', heated and evaporated to concentrate to 85% The CPL solution is sent to the low-element separation tower 3' and separated by heat medium (HMS), CPL and water vapor are evaporated to the pre-water removal tower 4', and the low-element body is pumped to the depolymerization tower 5 through the low-element b...

AI Technical Summary

Problems solved by technology

[0009] The technical problem to be solved by the present invention is to provide a system and method for improving the quality of recovered caprolactam and improving the recovery process, improve the quality of recovered CPL, reduce the amount of rectification slag discharge, and solve the problems of pre-water removal and rectification pipeline equipment blockage Problem, dispose of the phosphoric acid and oligomers evaporated from the depolymerization tower

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