磷矿颗粒流态化特性的实验研究

摘要

The fluidization characteristics of phosphate ore particles with sizes varying from 54 to 600 μm and densities of 2 252-2 665 kg/m3 were experimentally investigated in a fluidized bed of 1 m in height and 42 mm in interior diameter. The results indicate that the fluidization behaviors of phosphate ore particles strongly depend on their densities and mean sizes. The bed expansion ratio of the particles decreases with increasing mean sizes. The phosphate ore particles belonging to Geldart B can be fluidized smoothly. However, the particles in the mean size of 82 μm, belonging to Geldart A, are difficult to be fluidized, similar to the fluidization behavior of Geldart C. Large interparticle forces lead to plugging and channeling. The experimental values of minimum fluidization velocity were obtained by measuring the pressure drop across the bed. Several classical correlations were used to fit the experimental data of minimum fluidization velocity, and Thonglimp correlation for Geldart B agrees reasonably with the experimental data. A new correlation in explicit form was developed for better model of the minimum fluidization velocity.%在高1 m、内径42mm的流化床中,对粒径54-600 μm、密度2 252-2 665 kg/m3的磷矿颗粒的流态化特性进行实验研究.实验结果表明:磷矿颗粒粒径和密度对磷矿颗粒流态化行为有较大影响,床层膨胀比随着磷矿颗粒粒径的增大而逐渐减小.当磷矿颗粒属于Geldart B类颗粒时,流化较好；而当颗粒平均粒径为82 μm时,虽然属于A类颗粒,但由于颗粒间力较大,不易流化,出现柱塞状上升、沟流等不正常流化现象,表现出拟C类颗粒的流态化特性.通过测量床层压降,获得了磷矿颗粒的最小流化速度,并与不同的最小流化速度关联式的计算结果进行比较,计算结果显示Thonglimp关联式对B类颗粒更符合实验结果,并提出了适合磷矿颗粒的最小流化速度的关联式.