Impact of column geometry and internals on gas and particle flows in a fluidized bed with downward solids circulation: Effect of lateral injection profile and baffles

Abstract

This paper investigates how solids flow in a circulating fluidized bed can be modified by adding baffles and modifying gas injection locations, and how these changes suggest strategies for a reduction of liquid carryunder in the stripper in Fluid Cokers™. A Computer-Aided Radioactive Particle Tracking (CARPT) method was used with a pilot unit operated at room temperature with the same flux of recirculating coke particles as in the commercial unit. The lateral bitumen injections, and their impact on superficial gas velocity were simulated with 5 banks of 8 lateral gas injectors. In cokers, wet agglomerates that trapped injected bitumen carry unreacted liquid to the stripper. Radioactive simulated agglomerates were tracked to obtain formation-to-stripper time distribution profiles, for each lateral injection jet. Two methods were investigated to reduce liquid carryunder: the addition of a ring baffle and redistribution of liquid between banks. Experiments showed that carryunder can be reduced by either redirecting the bitumen feed from the lowest injection bank to higher banks, or adding a ring baffle with flux tubes in between the lowest and second-lowest injection banks. Combining both methods does not provide additional improvement.