加压循环流化床气固流动特性冷态试验

摘要

The flow behaviors of silica sand with the mean diameter of 0.347 mm and the bulk density of 1 435 kg/m3 in the riser were investigated with different loop seals and different exits of the riser at pressure from 0.1 to 0.5 MPa on a cold-model experimental facility of pressurized circulating fluidized bed with the riser diameter of 300 mm and the height of 8 700 mm.The results show that at the elevated pressure,the apparent solid holdup is lower at the upper part and higher at the bottom part of the riser,the apparent solid holdup tend to an uniform distribution with the increase of the superficial air velocity.When the bed inventory and superficial air velocity are kept unchanged,the solid holdup at the upper part of the riser increases with the elevated pressure.Normal circulation process can be established with both the loop seals with the diameters of 150 mm and 200 nun,the solid holdup distribution in the riser can not be changed with the diameter variation of the loop seals.The apparent solid holdup at the top of the riser can be increased with an abrupt exit of the riser.%利用提升管直径为300 mm、高度为8 700 mm的加压循环流化床冷态试验台,以平均粒径为0.347 mm、堆积密度为1 435 kg/m3的石英砂为床料,考查不同压力(0.1～0.5 MPa)、不同返料器、提升管顶部凸头结构对提升管内气固流动特性的影响.结果表明:加压条件下,提升管内的表观颗粒体积分数呈上小下大分布,随表观气速的增加逐渐趋于均匀分布;床料量和表观气速一定的情况下,增加压力可显著增大提升管上部的表观颗粒体积分数;采用φ150和φ200返料器均可建立正常的物料循环过程,改变返料器的直径并未改变提升管内的表现颗粒体积分数分布;提升管顶部采用凸头结构可增大提升管顶部的表观颗粒体积分数.