Hydrocracking Process - continued

The figure provided here illustrates a schematic diagram for a two-stage hydrocracking process.

The term "fresh gas" at the top of the figure indicates fresh hydrogen. Notice that fresh feed (lower left hand corner) passes through a heat exchanger and then mixes with preheated hydrogen, before being routed into the first stage reactor. In this reactor, catalysts convert sulfur and nitrogen compounds to hydrogen sulfide and ammonia. Limited hydrocracking also occurs. In this context the term “hydrocracking” indicates breaking of larger hydrocarbon molecules into smaller molecules in presence of hydrogen.

In the first stage only a limited amount of hydrocracking takes place. The stream “A” indicates injection of fresh hydrogen as quench gas – needed to control the reaction.