Process and device for distilling polymerization-prone compounds

Abstract

In a process for distilling polymerization-prone compounds from liquid mixtures of matter which, apart from the readily polymerizable compound, also contain other components and also polymerization inhibitors, the evaporator is operated in forced circulation and at a pressure which makes possible superheating of the liquid with respect to its boiling point at the pressure within the distillation column. This is achieved by transporting the superheated liquid against a flow restrictor, e.g. an orifice plate. The liquid which is expanded and partially evaporated on passage through the flow restrictor is returned to the distillation column. In this manner the formation of an open vapour space in the evaporator circuit after heating downstream of the heat exchanger is avoided in that, in the design of the evaporator of the prior art, formation of polymer deposits frequently occurs.

Description

technical field [0001] The present invention relates to a process for the distillation treatment of mixtures of substances comprising readily polymerizable compounds. In particular, the invention relates to the distillation purification of acrylic acid or methacrylic acid. The invention also relates to equipment for carrying out the process according to the invention. Background technique [0002] Acrylic acid and its esters are increasingly used throughout the world and mainly in the production of polymers. As explained in Ullmann's Encyclopedia of Industrial Chemistry (Sixth Edition, electronic distribution 1998), under the key words "acrylic acid and esters", most commercially used acrylic acid is produced by Produced by the selective oxidation of propylene, it also represents the starting material for acrolein. The selective oxidation of propylene is carried out in the gas phase as a heterogeneously catalyzed reaction using air as oxidant. The acrylic acid is first s...

AI Technical Summary

Problems solved by technology

However, when applying this teaching, problems arise, especially during start and stop operations, since the then required linear evaporation rate cannot or can no longer be maintained

Furthermore, the integral formation of the evaporator and condenser further reduces the available working volume for rectification and thus reduces the production capacity of the distillation column

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