循环床提升管内轴向压力梯度和物料浓度的分布特性

摘要

Based on the pressure data at different heights in a 3.6m-high CFB riser,the variation of axial pressure gradient in the riser was analyzed;and through making use of the differential pressure method,the axial distribution characters of material concentration in the riser were discussed to show that both superficial gas velocity and material's particle size can influence the pressure gradient and material concentration;the pressure gradient decreases gradually along the riser and the axial material concentration unevenly distributes;the increase of superficial gas velocity can reduce both variation of pressure gradient in the riser and uneven distribution of material concentration as well as the total pressure drop consumed by the material particles' motion;regarding the fine particles,they have even pressure gradient and concentration in the riser and the overall pressure drop they consumed in the motion is relatively smaller.%以3.6m高循环床提升管内轴向不同高度测点的压力数据为基础,分析了管内轴向压力梯度的变化规律,并通过压差法对提升管内轴向物料浓度的分布特性进行了研究,得出了表观气速和物料颗粒粒径的变化对二者的影响.结果显示,提升管内轴向压力梯度沿管上升方向逐渐减小,物料浓度在轴向方向上呈上疏下密的不均匀分布趋势.增加表观气速,可以减小管内上下压力梯度的差异,改善颗粒浓度分布的不均匀程度,减小颗粒流动过程中消耗的总压降.而相对于粗大粒径颗粒,细小颗粒在提升管内流动时轴向压力梯度和浓度分布都更加均匀,整个流动过程所造成气体的总压降也相对更小.