Patent GB-1112366-A (GB)
Title: Process for the purification of crude vinyl chloride
Inventor: ROLAND KLAUS
IPC: C07C17/38
Filed: 1965-10-07
Abstract: Hydrogen chloride is removed from crude vinyl chloride by absorption in dilute hydrochloric acid.  The concentrated hydrochloric acid formed may be removed and used to treat acetylene or acetylene/ethylene mixtures to form more vinyl chloride, the dilute acid from this process being returned and used to absorb more hydrogen chloride impurity.  Alternatively the concentrated acid may be partly removed and water added in its place.  In either case the absorption apparatus is cooled by direct contact with a stream of evaporating crude vinyl chloride passing to the absorption apparatus. In the Fig. (not shown), a stream of acetylene enters heat exchanger 2 at 1 where it is cooled with brine to about 0 DEG  C., condensed water being removed. The stream is then washed with 39% hydrochloric acid at - 10 DEG  C. in tower 3 before passing to mixing chamber 6 where further hydrogen chloride is added, and thence to reactor 8. The effluent stream is washed and cooled in tower 9 to approximately 25 DEG  C. by contact with concentrated hydrochloric acid which has been cooled with brine in heat exchanger 10.  The stream is then washed in tower 11 with dilute hydrochloric acid passed by pipe 5 from tower 3, liquid vinyl chloride being added at 13 and concentrated hydrochloric acid being removed by pipe 12 for recycling to tower 3.  The stream is then further washed with dilute hydrochloric acid in tower 14, the concentration of the acid being kept at 10-20% by bleeding off acid at 16 and adding water at 15. The last traces of acid are removed in tower 17 by washing with potassium carbonate solution before the stream leaves at 18 for such further processing as high pressure distillation. Liquid vinyl chloride for column 11 is preferably of the same composition as the crude stream and may be obtained from the distillation column.ALSO:Hydrogen chloride is removed from crude vinyl chloride by absorption in dilute hydrochloric acid.  The concentrated hydrochloric acid formed may be removed and used to treat acetylene or acetylene/ethylene mixtures to form more vinyl chloride, the dilute acid from this process being returned and used to absorb more hydrogen chloride impurity. Alternatively the concentrated acid may be partly removed and water added in its place.  In either case the absorption apparatus is cooled by direct contact with a stream of evaporating crude vinyl chloride passing to the absorption apparatus.  In the Figure (not shown), a stream of acetylene enters heat exchanger 2 at 1 where it is cooled with brine to about 0 DEG C., condensed water being removed. The stream is then washed with 39% hydrochloric acid at -10 DEG C. in tower 3 before passing to mixing chamber 6 where further hydrogen chloride is added, and thence to reactor 8.  The effluent stream is washed and cooled in tower 9 to approximately 25 DEG C. by contact with concentrated hydrochloric acid which has been cooled with brine in heat exchanger 10.  The stream is then washed in tower 11 with dilute hydrochloric acid passed by pipe 5 from tower 3, liquid vinyl chloride being added at 13 and concentrated hydrochloric acid being removed by pipe 12 for recycling to tower 3.  The stream is then further washed with dilute hydrochloric acid in tower 14, the concentration of the acid being kept at 10-20% by bleeding off acid at 16 and adding water at 15.  The last traces of acid are removed in tower 17 by washing with potassium carbonate solution before the stream leaves at 18 for such further processing as high pressure distillation. Liquid vinyl chloride for column 11 is preferably of the same composition as the crude stream and may be obtained from the distillation column.