Gas transfer between a central jet and a large two-dimensional gas-fluidized bed

Experimental study of gas mixing in a spout‐fluid bed

“…The actions of bubbles can promote gas mixing 15. After examining the effect of fluidizing gas flow rate on the gas mixing in a jetting fluidized bed, Gbordzoe et al14 indicated that when Q f / Q mf increases from 1.0 to 2.0, a profusion of fluidizing gas entered into the jet by convention, the dense phase in this case was well mixed, and bubbles appeared and were also entrained into the spout jet.…”

“…The gas mixing mechanism in spout‐fluid beds is complex and has not yet been fully elucidated, although the following discussion might be helpful. The previous investigation on jetting fluidized bed14 indicated that diffusive transport of tracer gas could be considered negligible compared with convective transport. Similar conclusions have been drawn by Yang et al12 Yang13 also investigated the gas interchange between the jet and the annular dense region of semicircular jetting fluidized beds in 3‐cm and 3‐m diameters.…”

“…Some previous investigations6, 12‐19 injected one nonactive gas tracer (such as helium, carbon dioxide, ozone, or argon) to study the gas mixing. For jetting fluidized beds, generally, tracer gas was injected into the jet (no tracer gas was injected into the fluidizing gas) to study gas transfer from the jet to the annular dense region, or tracer gas was injected into the fluidizing gas (no tracer gas was injected into the jet) to study gas transfer from the annular dense region to the jet region 12‐15. Gas transfer from the jet to the annular dense region and that from the annular dense region to the jet cannot be detected simultaneously.…”

“…A number of published studies in the literature12‐19 have reported valuable results of gas mixing in dense gas–particle flow systems. However, thus far there has been little information concerning the gas mixing in jetting fluidized beds and spout‐fluid beds; rather, most investigations16‐19 focused on circulating fluidized beds.…”

“…For jetting fluidized beds, Yang et al12, 13 investigated gas interchange between the jet and the annular dense region of the semicircular jetting fluidized bed, in diameters of 3 cm and 3 m, by injecting the helium tracer into the fluidizing gas (no tracer gas was injected into the jet) or by injecting the helium tracer into the jet (no tracer gas was injected into the fluidizing gas). Gbordzoe et al14 studied the gas mixing in a large two‐dimensional jetting fluidized bed using a V‐grid air distributor and ozone as a nonreactive tracer gas. The effect of the fluidizing gas flow rate on gas transfer from the jet into the dense phase was discussed; the velocity of the jet was kept constant, whereas the fluidizing gas velocity varied from u mf to 3.0 u mf .…”