Investigations on fluid dynamics of binary particles in a dual fluidized bed reactor system for enhanced calcium looping gasification process

This paper studies the mixing and movement of char in a dual fluidized bed for an enhanced calcium looping gasification process. The gasifier is a compact fluidized bed, consisting of a lower bubbling fluidized bed and an upper riser. The solid recirculation flux can be controlled by three loop seals. Quartz sand was used as a calcium-based sorbent and Chinese rice as the char. No flotsam behavior was observed in the bubbling fluidized bed. Experimental results reveal that the higher fluidization rate in the gasifier and the larger solid recirculation flux promoted char mixing. An increasing system char concentration decreased char mixing but led to higher char concentrations in the recirculation stream. The char holdup in the upper riser was primarily dependent on the fluidization rate in the gasifier. High solid recirculation flux with a low fluidization rate in the gasifier would benefit hot rig operation.