Page 27 - Fluid Catalytic Cracking Handbook
P. 27
Process Description 11
Pivot
Cyclone Dipleg
Restraint
PLAN
Pivot
Cyclone Dipleg*
Restraint
ELEVATION
Figure 1-8. Typical trickle valve (courtesy of Emtrol Corporation),
Stripping Section
As the spent catalyst falls into the stripper, hydrocarbons are adsorbed
on the catalyst surface, hydrocarbon vapors fill the catalyst pores, and
the vapors entrained with the catalyst also fall into the stripper.
Stripping steam, at a rate of 2 to 5 Ibs per 1,000 lbs (2 kg to 5 kg
per 1,000 kg,) is primarily used to remove the entrained hydrocarbons
between catalyst particles. Stripping steam does not address hydro-
carbon desorption and hydrocarbons filling the catalyst pores. How-
ever, reactions continue to occur in the stripper. These reactions are
