Prepn. of vinyl chloride from 1,2-di:chloroethane - by thermal decomposition, with cooling of effluent gas in three stages

摘要

Parent patent described the prepn. of vinyl chloride by thermal decomposition of 1,2-dichloroethane, where the effluent gas mixt. leaving the reactor is cooled indirectly by a liq. or gaseous coolant, and is then sepd. by distn. Cooling is in at least 2 stages, at an average rate per second of 1/10 of the temp., the deg. C, of entry into the indirect cooling zone, until the temp. is 220-120 deg. C. The heat given up to the coolant is used to heat the appts., and the decomposition gas mixt., opt. with a liq. condensate formed from it, is cooled (in)directly in at least 1 further stage. In this addn., the decomposition gas mixt. is cooled in the following stages: (1) indirect cooling to about 220 deg. C, (2) partly direct and partly indirect cooling to about 140 deg. C, with intermittent addn. of a liq. contg. mainly 1,2-dichloroethane (I), and (3) (in)direct cooling in at least 1 further stage, to the temp. of entry into the column in which HCl is sepd. from the thermal decomposition prods. The efficiency of the process is improved, and the interval between times of shutting down the plant for cleaning is lengthened. Formation of deposits on the walls during stage (2) is prevented or reduced.