Patent ID: 7718145

Claim:
A polyisocyanate production system comprising: a polyisocyanate producing unit for producing polyisocyanate by reacting carbonyl chloride with polyamine, a hydrogen chloride purifying unit to which hydrogen chloride produced secondarily in the polyisocyanate producing unit is supplied to purify the hydrogen chloride, a chlorine producing unit to which the hydrogen chloride purified in the hydrogen chloride purifying unit is supplied and in which the hydrogen chloride is oxidized to produce the chlorine, a hydrochloric acid producing unit to which the hydrogen chloride purified in the hydrogen chloride purifying unit is supplied and in which the hydrogen chloride is absorbed in water to produce a hydrochloric acid, a first adjusting unit for adjusting an amount of hydrogen chloride supplied from the hydrogen chloride purifying unit to the hydrochloric acid producing unit, a second adjusting unit for adjusting an amount of hydrogen chloride supplied from the hydrogen chloride purifying unit to the chlorine producing unit, and a control unit for controlling the second adjusting unit so that an amount of hydrogen chloride supplied from the hydrogen chloride purifying unit to the chlorine producing unit is kept constant and controlling the first adjusting unit so that an inner pressure of the hydrogen chloride purifying unit is kept constant, wherein the hydrogen chloride purifying unit is connected to the polyisocyanate producing unit on a supply side of the hydrogen chloride purifying unit and to the chlorine producing unit and the hydrochloric acid producing unit in parallel on a discharge side of the hydrogen chloride purifying unit.