Thermal cracking of hydrocarbon to ethylene etc. - using water with hydrogen and/or methane to increase yield and reduce coking (HUT 28.5.81)

摘要

In the thermal cracking of hydrocarbons to ethylene and other prods., the diluent is water with hydrogen and/or methane. The wt. ratio diluent/hydrocarbon is 0.25-0.50 for gaseous feedstocks and 0.5-1.2 for liq. feedstocks, and the wt. ratio (H2 and/or H2 equiv. of CH4)/hydrocarbon is 0.0025-0.0195. Pref. the wt. ratio H2/hydrocarbon is 0.004-0.01. The ethylene and propylene yields are higher than with water as the only diluent, the effects being greater if ethane and propane prod. are recycled for cracking either in a separate furnace or mixed with the hydrocarbon feed. The raffinates from C4, C5 and pyrolysis gasoline streams may also be recycled. The H2 may be added as the CH4 rich H2 stream sepd. from the cracker.