An FCC process comprising an enlarged riser section and a distributor in an elevated position and with an opening in its tip away from riser walls may reduce coke build-up along the interior walls of a riser. Catalytic mixing may be improved, which could reduce riser coking by increasing hydrocarbon contact with catalyst before contacting the riser wall. Increasing the distance between the introduction of the hydrocarbon and the riser wall may increase this likelihood for hydrocarbon-catalyst contact. Highly contaminated hydrocarbons cause greater coking than do normal hydrocarbons and this FCC process may be effective in decreasing riser coking on such heavy hydrocarbons.
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