Flow dynamics and contact efficiency in a novel fast-turbulent fluidized bed with ring-feeder internals

• Fast-turbulent fluidized bed (FTFB) riser with expanding section and ring-feeder was investigated.
• Two types of ring-feeder (mixed and vortex) were used to improve gas–solid contact efficiency.
• Two probability peaks of solid fraction signals existed in FTFB riser with vortex ring-feeder.
• Ring-feeder structure affected flow dynamics and gas–solid contact efficiency in FTFB risers.

The flow dynamics in a novel fast-turbulent fluidized bed (FTFB) with middle-upper expanding structure and two different ring-feeder internals (mixed and vortex ring-feeder) were studied to achieve a reduction in gasoline olefin production. Compared with a conventional circulating fluidized bed, the novel FTFB displayed unique characteristics and advantages. A higher solids holdup and more uniform solids holdup distribution existed in the diameter-expanding region, especially for the FTFB with vortex ring-feeder structure. A probability density distribution analysis indicated that the novel fluidized bed could reduce gas–solids segregation and enhance gas–solids interaction. A constant carbon dioxide tracer system was used to simulate the reactant gas distribution. The gas–solids contact efficiency was defined according to the solid dispersibility and the amount of gas covering the solid surface. Novel FTFB risers, especially those with vortex ring-feeders, have a much higher gas–solids contact efficiency than that of traditional risers.

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