Patent ID: 7749372

Claim:
A method for treating gaseous effluent from a hydrocarbon pyrolysis unit, the method comprising: (a) cooling the gaseous effluent at least to a temperature at which tar, formed by reaction among constituents of the effluent, condenses; (b) passing the mixed gaseous and liquid effluent from (a) through at least one tar knock-out drum, where the condensed tar separates from the gaseous effluent; (c) cooling the gaseous effluent from (b) to less than 100° C. to condense a hydrocarbon fraction having a boiling point range between about 150° C. to about 540° C. from said effluent; (d) separating C 2 to C 4 olefins from the hydrocarbon fraction condensed in (c) without a primary fractionation tower; and then (e) distilling said separated hydrocarbon fraction so as to separate a pyrolysis gasoline fraction having a boiling point range between about 150° C. to about 230° C.