| 摘要 |
1,174,147. Vinyl chloride. INSTITUT FUR CHEMIEANLAGEN. 11 Aug., 1967, No. 37022/67. Heading C2C. Vinyl chloride is purified by removing therefrom hydrogen chloride and high boiling impurities by subjecting crude vinyl chloride in vapour form to (a) a washing step in which it is contacted with water or hydrochloric acid and optionally a neutralization step in which any remaining hydrogen chloride is removed, e.g. by contact with alkali, and (b) a distillation step in which vinyl chloride and low-boiling impurities are separated from high-boiling impurities, the steps being combined partly or wholly by contacting the crude vinyl chloride during step (a), at least during the washing step, with a countercurrent flow of liquid vinyl chloride enriched with high-boiling impurities obtained as reflux in step (b). In Fig. 1, crude vinyl chloride supplied at 1 is washed in absorption tower 2, scrubbed with alkali in neutralization tower 7 and fractionated in column 6, condensed vinyl chloride being supplied thereto by line 12 and the vinyl chloride containing high boiling impurities being returned from the bottom of column 6 to the top of tower 2. Alternatively (Fig. 2, not shown), the reflux from the fractionation may be returned to the absorption tower via the neutralization tower or (Fig. 3, not shown) the absorption and fractionation may be effected in a single tower. The hydrochloric acid obtained as effluent from the washing stage may be used for drying acetylene or other hydrocarbons used in the production of vinyl chloride. |
