鼓泡流化床内颗粒速度分布的研究

在内径0.185m 的鼓泡床内,采用PV-5A型速度仪考察不同表观气速下两种粒径GeldartB类物料(玻璃微珠)在不同轴向位置颗粒速度径向分布规律。结果表明,在床层底部颗粒速度分布与分布器设计密切相关,而远离分布器的上部区颗粒速度主要受气泡行为影响,表现为中心区域大而边壁附近小,且随着表观气速的增大这种趋势变的更加明显;同时在这两个区域之间存在一个过渡区,该区域内分布器的影响明显减弱,导致颗粒速度的径向分布逐渐趋于一定的规律;而在相同轴向位置处颗粒速度变化幅值的影响会随着表观气速的增大变得剧烈。

Particle Velocity Distribution in the Bubbling Fluidized Bed

Radial velocity distributions of two kinds of glass beads, belonging to Geldart type B classification, were investigated at different axial sections in the bubbling fluidized bed with an inner diameter of 0. 185 m under different superficial gas velocities. Local particle velocities were measured by using the PV--5A fiber--optical probe. The experimental results indicate that the radial distribution of particle velocities in the bed bottom zone is irregular, where the design of the distributor is dominated. When the axial section is far from the distributor, the particle velocities are higher in the center than those near the wall within the bed, which becomes obvious with increasing superficial gas velocity. Meanwhile, there exists a transitional zone between the above two zones, where the effect of the distributor tends to be weakened. This leads that the radial distribution of particle velocities is regular. Moreover, the amplitude of particle velocity at the same axial position changes sharply with an increase of superficial gas velocity.