Process for separation of aqueous amine solutions by distillation

摘要

Distillative separation of aqueous amine solution includes performing distillation in distillation columns connected in series and operated at different pressures, partially condensing vapor leaving the column operating at higher pressure and using released heat to heat the bottom of column operating at lower pressure, feeding amine solution into a first of the columns, and removing purified amine as bottom product from a last column. Distillative separation of aqueous amine solution obtained from hydrogenation of nitroaromatic compounds includes performing distillation in at least two distillation columns (A, E) connected in series and operated at different pressures, where at least one distillation column is operated at higher absolute pressure at the column head of 2-20 bar and at least one distillation column is operated at lower absolute pressure at the column head of 0.1-10 bar; partially condensing vapor leaving the distillation column operating at higher pressure and heating the bottom of the distillation column operating at lower pressure with the heat released from the vapor; feeding amine solution into a first of the two distillation columns, and partially removing bottom product from the first distillation column and feeding it into the second distillation column; and removing purified amine as bottom product from a last distillation column.