大小二成分系Spout-Fluid Bedの流動特性 [in Japanese] Hydrodynamic Behavior in Spout-Fluid Beds of Binary Mixtures of Particles [in Japanese]
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大小二成分粒子群からなるSpout-Fluid Bedの流動特性を調べ, 大粒子単一粒子群の場合と比較した.中央ノズルからのガス流量と分散板からの補助ガス流量の割合によって, Spouting with aeration (SA) とSpouting with fluidization (SF) の2つの流動パターンが認められた.小粒子割合の増加に伴って, SA領域を形成するための操作領域は狭くなった.またSF領域を形成するための最小ガス速度の推算式を得た.<BR>次に, 大小二成分系のSA領域に対して, 最小のSA状態における層内圧力損失が補助ガス流量の増加で増加した.また全ガス流量一定で, アニュラス部通過ガス流速が補助ガス流量の増加によって増加した.なおそれらの値は, 大粒子単一系の場合より小さくなった.さらに全ガス流量一定で, 粒子循環速度が補助ガス流量の増加によって増加し, 平均スパウト径とファウンテン高さは減少し, それらの値は, 大粒子単一系の場合とほぼ同じ値であった.
The objectives of this study are to investigate the basic fluid characteristics for spout-fluid beds of binary mixtures of particles, and to compare the hydrodynamics with that of coarse particles only.<BR>As results, two patterns of flow in spout-fluid beds, that is, spouting with aeration (SA) and spouting with fluidization (SF), were mapped as the regions depending on the relative values of the central and auxiliary gas flow rates. The operation regions for SA were reduced by the increase of the ratio of fine particles. Also, a correlation for predicting the minimum SF velocity was presented.<BR>It was found that the overall bed pressure drop under minimum SA condition increased linearly and also the gas velocity through the annulus increased, as the proportion of the auxiliary flow rate to a fixed total gas flow rate was increased for operation in the SA region of binary mixtures. The values as described above were smaller than those in the case of using coarse particles only. Moreover, the particle circulation rate increased and also both the average spout diameter and the fountain height decreased, as the proportion of the auxiliary flow rate to a fixed total gas flow rate was increased.
- Chemical engineering
Chemical engineering 23(1), 59-66, 1997-01-10
The Society of Chemical Engineers, Japan