The lighter components formed in the Hydrocracker Reaction Unit are separated from the remaining residuum in the Hydrocracker Fractionation Unit.
The separated liquid is routed to a fractionation section for splitting into naphtha, jet kerosene, gas oil and heavy residuum. The feed enters the atmospheric fractionator where the vapours flow up the tower and are progressively condensed and removed.
Gas oil and jet kerosene are removed as side cuts while the naphtha and gas exit the top of the tower into the overhead systems. Here the naphtha is condensed and a portion returned to the tower as reflux. The non-condensed vapour from the overhead systems and the naphtha are directed to the Gas Recovery Unit. The jet kerosene and gas oil streams are routed to the Gas Oil and Naphtha/Jet Hydrotreater for further processing.
The non-vapourized portion of the feed entering the fractionator flows down the tower where it is stripped of light ends and removed as a bottoms product.
The atmospheric fractionator bottoms are heated and fractionated, under sub-atmospheric conditions, into light and heavy vacuum gas oils and vacuum residuum. The gas oils are removed as side products, combined, and routed to the Gas Oil Hydrotreater. The residuum is routed to the Delayed Coking Unit for further cracking into lighter fractions.
Used with permission (© SAIT Polytechnic, MacPhail School of Energy, 2009)