Vinyl Chloride from EDC Pyrolysis by Tosoh Technology

Published January 1990

Tosoh Corporation of Japan has developed an improved technology for ethylene dichloride (EDC) pyrolysis to vinyl chloride (VCM) by making better use of the cracking furnace and energy recovery from the cracked gas. In the improved process, preheated purified liquid EDC is evaporated through heat exchange with the cracked gas before being sent to the furnace. The company claims that the improved technology allows a 5-10% increase in VCM production per pass without any increase in by-product formation or energy loss. The increase is the result of extra available surface in the furnace, which would have been used for the evaporation of EDC in one of the two conventional techniques. At present, either preheated liquid EDC or vaporized EDC is used as a feedstream to the pyrolysis furnace in commercial practice. In PEP Report 5C, a conventional process with vaporized EDC as feed stream was presented.

In this review, SRI evaluates the Tosoh process (a conventional process modified with the Tosoh technique for the recovery of potential heat from the cracked gas) and compares its economics with those of the conventional EDC pyrolysis process updated from PEP Report 5C. The SRI evaluation indicates that the Tosoh process requires less total fixed capital than does the conventional process. The saving is mainly from the reduction in off-site investment. Because of close differences in both capital investment and production costs, we conclude that the Tosoh process is essentially equivalent economically to the conventional process.