Patent ID: 7544832
Filing Date: 2009-06-09
Classification: B01D,C07C

Abstract:
1. A method for preparation of diisocyanates with at least one distillation column and/or at least one vessel and at least one circulation evaporator, wherein the distillation column and/or the vessel are connected to the circulation evaporator via connecting elements which feed liquid from a bottom part of the distillation column and/or the vessel to the circulation evaporator below a lower tube sheet of the circulation evaporator, said method further comprises completely or partly feeding liquid (i) from a tray or from a stacked packing bed or from a dumped packing bed or from a liquid collector of the distillation column to the circulation evaporator below a lower tube sheet of the circulation evaporator, or (ii) as a feed stream external to the distillation column and/or the vessel to the circulation evaporator below a lower tube sheet of the circulation evaporator.