流動層内の濃厚ならびに希薄領域における粒子ホ-ルドアップおよび層と垂直挿入管壁間の伝熱係数

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The local weight-mean diameter, the local holdup of solid particles and the heat transfer coefficient between a bed and a vertically inserted tube wall were measured in a 12 cm I.D. fluidized bed using FCC particles with a broad size distribution. The weight-mean diameter of FCC particles was 65 μm and the minimum fluidization velocity was about 0.25 cm/sec.<BR>In a dilute zone which is formed above a bubbling dense zone, the local weight-mean diameter and the local holdup of particles decrease with distance from the upper surface of the dense zone and increase with increasing gas velocity. At a gas velocity of 50 cm/sec there is no notable difference in the weight-mean diameter of particles throughout the bed, but a longitudinal holdup distribution of particles still exists.<BR>The heat transfer coefficient is a function of holdup of particles, weight-mean diameter of particles, gas velocity and physical properties of gas and solid, and is independent of tube diameter.<BR>An empirical equation for the heat transfer coefficient is obtained.
社団法人化学工学会の論文