Patent ID: 7981374

Claim:
Hydrocarbon cracking apparatus comprising: (a) a reactor for pyrolyzing a hydrocarbon feedstock, the reactor having an outlet through which gaseous pyrolysis effluent can exit the reactor; (b) at least one primary heat exchanger connected to and downstream of the reactor outlet for cooling the gaseous effluent; (c) at least one secondary heat exchanger connected to and downstream of the at least one primary heat exchanger for further cooling said gaseous effluent, said at least one secondary heat exchanger having a heat exchange surface which is maintained, in use, at a temperature such that part of the gaseous effluent condenses to form a liquid coating on said surface, thereby cooling the remainder of the gaseous effluent to a temperature at which at least a portion of the tar, formed during pyrolysis, in said gaseous effluent, condenses, wherein said primary and secondary heat exchangers comprise heat exchange tubes and each heat exchange tube of said secondary heat exchanger has an internal diameter equal to or greater than that of each heat exchange tube of said primary heat exchanger; and (d) means for separating said condensed tar and said gaseous effluent.