Allyl Chloride Production

The process under analysis comprises three major sections: (1) Chlorination; (2) Propylene Recovery; and (3) Product Treatment.

Chlorination. The liquid propylene is sent to an evaporator, being vaporized and preheated to the chlorination reaction temperature. It is then fed, along with chlorine, to an adiabatic reactor, where the chlorination reaction is carried out, producing allyl chloride and by-products.

Propylene Recovery. The reactor effluent is cooled and routed to the Prefractionator, where HCl and unreacted propylene are separated from chloropropenes, dichloropropenes, chloropropanes and heavier compounds. The Prefractionator overhead stream, containing HCl and propylene, is passed in countercurrent with demineralized water in the HCL Absorber, forming a hydrochloric acid solution with 32% purity that is stored. The off-gas, mostly propylene, is sent to Caustic Wash, which removes residual HCl. The washed propylene is compressed and routed to a decanter and dried by adsorption for water removal. Part of dried propylene is returned to the feed, and the remainder is recycled to the Prefractionator.

Product Treatment. The bottom stream from the Prefractionator, rich in Allyl Chloride, is directed to the Light-ends Column, which strips components lighter than Allyl Chloride, that are burned for fuel. The bottom product of this column is sent to the Purification Column, where Allyl Chloride is removed form the top, condensed and routed to storage, while its bottom is sent to Dichloropropene Column. This last distillation step separates dichlorides, collected from the top and sent to storage, from heavy components that are burned for fuel.