高通量循环流化床上升管气固流动特性实验研究

Experimental Study on Gas-solid Flow Characteristic in High-flux Circulating Fluidized Bed Riser

以直径0.06m、高5m的高通量循环床提升管中气固两相流大量试验数据为基础,考察在高颗粒循环量和较高气体表观流速下,平均粒径为140μm、密度为2700kg/m3的GeldartB类颗粒气固流动特性。试验发现,截面平均颗粒浓度分布总体上为下浓上稀,并随操作气速的增大而减小,悬浮上升流动结构区域随着颗粒循环速率的增大而向上延伸。滑移因子、截面平均颗粒浓度与无量纲滑移速度之间存在显著相关性。此外,床层总压降和截面平均颗粒浓度随固气质量比的增加而增加,在上升管下部截面平均颗粒浓度受固气质量比的影响比上部大。

The gas-solid flow characteristics under high-flux and high superficial gas velocity were investigated with the experimental data of pressure gradients of gas-solid two-phase flow in high-flux CFB riser with diameter of 60 mm and height of 5 000 mm. Geldart group B- particles with mean diameter of 140μm and density of 2700kg/m3 were used as bed materials. It was found that the apparent solids holdups decrease with the increase of axial height of riser, and it decreased with increasing superficial gas velocity. The increase of solids mass flux results in the upward extend of dense suspension upflow （DSU） structure. There were significant correlations between the dimensionless apparent slip velocity, apparent solids holdup and slip factor. The riser total pressure drop and apparent solids holdup increase with the solids-to-air mass flow ratio, and there is greater effect of solids-to-air mass flow ratio on apparent solids holdups in lower part of riser.