Patent ID: 7780843

Claim:
A method for cooling and recovering energy from tar precursor-containing gaseous effluent from hydrocarbon pyrolysis, the method comprising: (a) passing said gaseous effluent obtained by steam cracking feeds that are heavier than naphthas, through at least one dry-wall quench exchanger in the absence of added liquid quench to provide, by indirect heat exchange, a cooled effluent consisting of gas above the temperature at which said tar precursor initially condenses; (b) passing the cooled effluent from (a) through at least one wet-wall quench exchanger comprising a tube having a process side and a shell side, said process side being covered with a substantially continuous liquid film, to provide a gaseous effluent stream of reduced tar content below 287° C. (550° F.), and below the temperature at which said tar precursor initially condenses, the at least one wet-wall quench exchanger further comprising an inlet transition piece comprising thermally insulating material.