Side mounted fcc stripper with two-zone stripping

Abstract

A side-by-side reactor vessel and stripping vessel arrangement uses a rejection vessel to collect the catalyst from the bottom of a reactor vessel and eliminate stagnant layers of catalyst within the reactor vessel while increasing the efficiency of a stripper vessel located to the side of the reactor. Catalyst containing entrained and sorbed hydrocarbons pass from the bottom of a reactor vessel into the small diameter rejection vessel that provides a hydrocarbon rejection zone and uses a fresh stripping medium to maintain a dense fluidized bed from which entrained hydrocarbons are quickly disengaged from the catalyst and travel upward into the reactor vessel. Partially stripped catalyst flows through a passageway that extends horizontally to a stripping vessel that contains a conventional stripping zone. In the stripping vessel, catalyst counter-currently contacts additional stripping medium which removes sorbed hydrocarbons from the catalyst surface. Stripped catalyst is transferred from the stripper vessel to a regeneration zone and stripping gas is returned by the horizontally extending passageway to an upper section of the rejection zone where it recontacts incoming catalyst before passing upwardly into the reactor vessel. In addition to eliminating the stagnant layer of catalyst often associated with a side-by-side reactor and stripper arrangement, the invention also provides additional effective reactor length to accommodate longer cyclones and increases the efficiency of the stripping operation by providing quick disengagement of readily stripped hydrocarbons and additional contacting between the catalyst and stripping gas.