METHOD FOR PROCESSING WASTEWATER AND EXHAUST GAS CONDENSATES FROM THE POLYMERIZATION OF VINYL ACETATE AND ETHYLENE IN AN AQUEOUS MEDIUM

摘要

A method for processing wastewater and exhaust gas condensates from the polymerization of vinyl acetate and ethylene and optionally other comonomers in an aqueous medium by suspension or emulsion polymerization employs relieving pressure after completion of the polymerization of the polymerization batch and discharging the polymer dispersion. During the relieving, the gaseous phase is removed by means of a compressor. Optionally, the gaseous phase occurring during stripping is removed by the compressor and cooled by one or more heat exchangers before entry into the compressor. The liquid phases occurring in the compressor and optionally in the heat exchanger are separated from the gaseous phase and the liquid phases are given to a rectification column, and separated into a vinyl acetate monomer phase and a wastewater phase, and the vinyl acetate monomer phase is resupplied to polymerization.

主权项

1. A method for processing wastewaters and waste-gas condensates from the polymerization of vinyl acetate and ethylene and optionally further comonomers in an aqueous medium, by the suspension or emulsion polymerization process under a pressure of 5 to 100 bar abs., in which, after the end of the polymerization, the polymerization batch is let down to a pressure of 0.1 to 5 bar abs., and is optionally treated with inert entraining gases (stripping) and the polymer dispersion is drained off, characterized in that
A) during letdown the gaseous phase is taken off by means of a compressor 5, B) the gaseous phase obtained during stripping is optionally taken off by means of the compressor 5 and, before entering the compressor, is cooled by means of one or more heat exchangers 8, and C) the liquid phases (7,11) obtained in the compressor 5 and optionally in the heat exchanger 8 are each separated from the gaseous phase, and D) are applied to a rectifying column 24, and are separated into a vinyl acetate monomer phase (34/44) and into a wastewater phase (25/29), and the vinyl acetate monomer phase is returned to the polymerization.