Hydrocracker Reaction Unit
This unit employs a suspended or "ebuliated catalyst-bed" technology which
allows onstream addition and withdrawal of catalyst and eliminates the need for shutdown
for catalyst changeout and maintains uniform catalyst activity. The catalyst is maintained
in a fluidized state by the upward velocity of the feed. This turbulence provides
uniform heat distribution and efficient contact on the catalyst between the residuum and
hydrogen.
Atmospheric residuum from the Crude Unit is preheated
in a fired heater and mixed with a hydrogen rich gas stream. This preheated mixture enters
the expanded bed of catalyst where cracking of the residuum occurs. The hydrogen
reacts with the cracked compounds, forming a partially desulphurized, demetallized,
denitrified and hydrogen-saturated product. Hydrocracking yields full range boiling
products, converting approximately 60 percent volume of the initial vacuum residuum to
lighter fractions.
The reaction products and excess hydrogen pass through a series of flashing and cooling
stages to separate the vapour from the liquid. The flashing vapours are stripped of
hydrogen sulphide in an amine absorber and the hydrogen rich stream is recycled to the
reactors. A purge gas stream maintains recycle gas purity and is routed to a
Pressure Swing Adsorption (PSA) Unit for hydrogen recovery.
The separated liquid is routed to the Hydrocracker Fractionation Unit for splitting
into naphtha, jet kerosene, gas oil and heavy residuum.
