ES396040A1 - Process for the purification of waste water from plants for the production of acrylonitrile - Google Patents

Abstract

Procedure for the purification of the residual waters of the facilities for the production of acrylonitrile, by means of oxidation in the gas phase of propylene and ammonia with oxygen with solid catalysts, which were used for the separation of acrylonitrile from gas mixtures that, in addition to acrylonitrile, contain acetonitrile, prussic acid, water, inert and organic compounds, and that is, totally or almost totally free of acrylonitrile, acetonitrile and prussic acid but that still contain volatile and toxic organic compounds, as well as high boiling point and resinous, characterized in that the residual water, in order to remove and destroy the toxic compounds, is treated in a distillation column with 7 to 20 distributor plates, which has been arranged after the lower end of a column for the separation of acetonitrile from the residual water, at temperatures between 100º and 125ºC and pressures between 0 and 2 atmospheres, with 0.4 to 1.0 tons of steam per ton of residual water that flows into the distillation column, if necessary after adding 0.005 to 0.2% by weight of an organic amine, then the foot outlet is fed to an evaporator and, in case given again, under the addition of an organic amine, it is evaporated, the vapors are used for heating the detoxification distillation column as well as the column for the separation of the acetonitrile from the washing water and, if appropriate after a Further biological purification is evacuated to a running water system, and the aqueous solution that is still in the liquid phase of the evaporator is extracted, containing from 1 to 60% by weight of high-boiling and resinous organic compounds. (Machine-translation by Google Translate, not legally binding)