Patent ID: 9061922
Filing Date: 2015-06-23
Classification: B01D,C02F,C08F,C08J

Abstract:
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 a 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 a first gaseous phase is taken off, and is optionally treated with inert entraining gases (stripping) and the polymer dispersion and a second gaseous phase is drained off, wherein A) during letdown the first gaseous phase is taken off by means of a compressor, B) the second gaseous phase optionally obtained during stripping is taken off by means of the compressor and, before entering the compressor, is cooled by means of one or more heat exchangers, and C) liquid phases obtained in the compressor and optionally in the heat exchanger are each separated from at least one of the first and second gaseous phases, and D) the liquid phases are applied to a rectifying column, and are separated into a vinyl acetate monomer phase and into a wastewater phase, and the vinyl acetate monomer phase is returned to the polymerization, wherein the wastewater obtained as bottom product in the rectifying column is purified further, and for that purpose is partially vaporized in a vaporizer, and the wastewater stream which remains after partial vaporization is removed.