不同颗粒流化床层中挡板受力特性对比

Comparison of force characteristics in two fluidized beds with different particles

颗粒性质对流化床内气固流动特性具有重要的影响,不同颗粒床层内气固流动特性的不同也将引起床层中内构件受力特性的变化。采用在测试挡板表面粘贴应变计的方法,系统对比测量了一个斜片挡板在FCC颗粒（Geldart A）和石英砂颗粒（Geldart B）两种流化床内受力特性的差异,并系统比较了操作参数变化时挡板在两种颗粒床层中受力特性变化规律的差异。结果表明,在相同的操作条件下,挡板在B类颗粒床层中受力载荷的均方根值大小约是A类颗粒床层中的2~3倍;除挡板安装在靠近分布器位置外,总体来讲,在两种颗粒的床层中,挡板所受载荷强度都随表观气速的增大而增大。但是,在两种颗粒床层中,挡板安装高度变化对挡板受力特性影响差异较大,在B类颗粒床层中所受载荷强度随着安装高度增大而增大,而在A类颗粒床层中所受载荷强度随安装高度增大呈现先减小后增大的趋势。此外,挡板倾角度θ在75°-90°之间变化时,挡板所受载荷强度在两种颗粒流化床中均随着挡板倾角增大呈现急剧下降的趋势,而当θ=0°-75°时,B类颗粒床层中挡板所受载荷强度随挡板倾角增大略有下降,而A类颗粒床层中挡板所受载荷强度变化并不十分明显。

Particle properties have significant effect on gas/solids flow characteristics, which results in significantly different force characteristics exerted in the internals immersed in fluidized beds of different particles. In this study, the dynamic force in a tested slat immersed in fluidized bed was measured by adhering strain gauges on its surface. The force characteristics of the slat were systematically compared in two beds of FCC catalyst particles（Geldart A） and silica sand particles（Geldart B）. The experimental results showed that the RMS load density acting on the slat in the bed of Geldart B particles was about 2—3 times higher than in the bed of Geldart A particles. Except installed near the bottom distributor, the measured load density on the slat increased with increasing superficial gas velocity in both beds. However, the effect of the installation height of the slat indicated great difference in the two beds. The measured load density on the slat increased with increasing installation height in the bed with Geldart B particles, while it decreased firstly and then increased with increasing installation height in the Geldart A particles bed. At θ =75ο—90ο, the measured load densities decreased sharply with increasing inclination angle in both beds. However, at θ =0ο—75ο, the measured load density decreased slightly with increasing inclination angle in the bed of Geldart B particles, while there was no obvious change in the bed of Geldart A particles.