Mitsui Chemicals, Inc.

Takao Naito

Masaaki Sasaki

Takashi Yamaguchi

Takuya Saeki

Hirofumi Takahashi

Kouichirou Terada

Kouji Maeba

Fumiaki Hirata

Masato Saruwatari

Tsugio Imaizumi

A polyisocyanate production method that can allow effective use of hydrogen chloride produced secondarily in a polyisocyanate production process, while allowing reduction of environmental burdens, and a polyisocyanate production system for performing the polyisocyanate production method. After chlorine is allowed to react with carbon monoxide to produce carbonyl chloride in a carbonyl chloride producing reactor, the carbonyl chloride produced in the carbonyl chloride producing reactor is allowed to react with polyamine in an isocyanate producing reactor to produce polyisocyanate. Then, after hydrochloric gas produced secondarily in the isocyanate producing reactor is purified in a hydrogen chloride purifying column, the purified hydrochloric gas is oxidized in a hydrogen chloride oxidizing reactor to produce chlorine. Thereafter, the chlorine thus produced is supplied to the carbonyl chloride producing reactor from a chlorine resupply line, so that it is allowed to react with carbon monoxide to produce carbonyl chloride.

Polyisocyanate production method and polyisocyanate production system

A polyisocyanate production system is provided that can stably produce chlorine from hydrogen chloride produced secondarily while reacting stably between carbonyl chloride and polyamine and can perform an effective treatment of the hydrochloric gas produced secondarily. A hydrochloric gas control unitcontrols a flow-rate control valveto keep constant an amount of hydrogen chloride supplied from a hydrogen chloride purifying tankto a hydrogen chloride oxidation reactorvia a second hydrochloric-gas connection lineto be constant, and also controls a pressure control valvebased on an inner pressure of the hydrogen chloride purifying tankinput from a pressure sensorto discharge the hydrochloric gas from the hydrogen chloride purifying tankto the hydrogen chloride absorbing columnvia a first hydrochloric-gas connection line, so as to keep an inner pressure of the hydrogen chloride purifying tankto be constant.

Polyisocyanate production system and gas treatment apparatus

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Kamisu, Japan

Takao Naito