The effect of vertical internal baffles on the particle mixing and graindrying characteristics in a batch fluidized bed column is investigated. Experimental work wascarried out in a 3m high rectangular fluidized bed d...The effect of vertical internal baffles on the particle mixing and graindrying characteristics in a batch fluidized bed column is investigated. Experimental work wascarried out in a 3m high rectangular fluidized bed dryer of cross sectional area of 0.15 m x 0.61 mat different operating conditions using paddy, a group D particle, as the fluidizing material. Theresults of the study showed that the fluidized bed dryer system with vertical internal baffles gavebetter particle mixing effect in the bed of particles than that without vertical internal baffles.This is due to the fact that the vertical internal baffle act as gas bubble breakers by breaking upthe large gas bubbles into smaller ones. The smaller bubbles cause a more vigorous mixing in the bedof particles before finally erupting at the bed surface. This improves the contacting efficiencyand enhanced the heat and mass transfer of the fluidized bed system. Thus a higher drying rate wasobtained in the falling rate period because the higher contacting efficiency increases theevaporation rate at the particle surface. However, the drying rate in the diffusion region showslittle improvement because the moisture diffusivity does not depend on the contacting efficiency.The fluidized bed dryer with vertical internal baffles could therefore be used in the initial rapiddrying stage in a two stage drying strategy for paddy. The insertion of vertical internal bafflesinto a fluidized bed system improves the processing of Group D particles in a fluidized bed systemespecially if the system is large in scale.展开更多
文摘The effect of vertical internal baffles on the particle mixing and graindrying characteristics in a batch fluidized bed column is investigated. Experimental work wascarried out in a 3m high rectangular fluidized bed dryer of cross sectional area of 0.15 m x 0.61 mat different operating conditions using paddy, a group D particle, as the fluidizing material. Theresults of the study showed that the fluidized bed dryer system with vertical internal baffles gavebetter particle mixing effect in the bed of particles than that without vertical internal baffles.This is due to the fact that the vertical internal baffle act as gas bubble breakers by breaking upthe large gas bubbles into smaller ones. The smaller bubbles cause a more vigorous mixing in the bedof particles before finally erupting at the bed surface. This improves the contacting efficiencyand enhanced the heat and mass transfer of the fluidized bed system. Thus a higher drying rate wasobtained in the falling rate period because the higher contacting efficiency increases theevaporation rate at the particle surface. However, the drying rate in the diffusion region showslittle improvement because the moisture diffusivity does not depend on the contacting efficiency.The fluidized bed dryer with vertical internal baffles could therefore be used in the initial rapiddrying stage in a two stage drying strategy for paddy. The insertion of vertical internal bafflesinto a fluidized bed system improves the processing of Group D particles in a fluidized bed systemespecially if the system is large in scale.
