Hydrocracking Process - continued

After the hydrocarbon stream leaves the first stage, it is cooled and liquefied and run through a hydrocarbon separator “C”. In this process, hydrogen does not liquefy and rises through the high pressure separator C into the suction side of a compressor “B”. The hydrogen is recycled to the feedstock by the compressor. The liquid flows down into the low pressure separator D. From this separator, the liquid is charged to a fractionator.

The fractionator bottoms are again mixed with a preheated hydrogen stream and charged to the second stage. Since this material has already been subjected to some hydrogenation, cracking, and reforming in the first stage, the operations of the second stage are more severe (higher temperatures and pressures). A large amount of hydrocracking takes place in the second stage. The products from the second stage are mixed with the products from the first stage and the cycle continues.