Covestro Deutschland Ag

Covestro Intellectual Property Gmbh & Co. Kg

Yuguo Gai

Wolfgang Taube

Zhangyong Ming

Volker Michele

Joachim Zechlin

Qiang Wei

Thomas Bludowsky

Yiming Mao

The invention relates to a method for cleaning a phosgene-conducting apparatus by pressurization with ammonia gas to constant pressure. In this way, phosgene residues in the apparatus to be cleaned are decomposed effectively.

Method for cleaning phosgene-conducting apparatuses

A process for quenching, in a quenching zone, a gaseous reaction mixture that includes a diisocyanate, phosgene and hydrogen chloride that is obtained in a reaction zone upstream of the quenching zone by phosgenation of a diamine in the gas phase. The process includes injecting a deposit preventing liquid in a deposit preventing zone located between the reaction zone and the quenching zone by passing the deposit preventing liquid through spray nozzles for the deposit preventing liquid at the entrance to the deposit preventing zone. Each spray nozzle for the deposit preventing liquid sprays the deposit preventing liquid (i) onto a wall segment of the deposit preventing zone that is adjacent to said spray nozzle for the deposit preventing liquid to produce a film of the deposit preventing liquid flowing along the wall, and/or (ii) to areas in a cross-sectional plane of the deposit preventing zone before the entrance to the quenching zone.

Process for quenching a gaseous reaction mixture obtained in the gas phase phosgenation of diamines

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Shanghai, China

Yuguo Gai