内构件对高密度提升管内气体混合行为的影响

在Φ18 6mm的提升管内 ,以空气和FCC颗粒为实验对象 ,采用气体稳态示踪技术对高密度提升管内气体混合规律研究的结果表明 :引入钝体的高密度提升管内 ,远离构件区域的气体在径向上的混合仍符合气体的拟均相二维扩散模型 ,颗粒的引入使得气体的径向扩散变差 .钝体的引入 ,使得床内流体产生强烈的绕流 ,径向分布变得均匀 .模拟结果表明 ,气体的径向扩散系数Er达到了 1.0× 10 ³cm² ·s^-1,比提升管 30cm² ·s^-1高出一个半量级 ,可很好地改善高密度提升管内气体的径向混合行为

EFFECT OF INTERNALS ON GAS DISPERSION IN HIGH DENSITY RISER

Experiment results of the effect of internals in high density circulating fluidized bed (HDCFB) on gas dispersion were reported in this paper .Gas dispersion behavior was investigated by using steady gas tracer (propylene) technique and FCC particles (particle density 1398 kg·m ^-3 , mean diameter 54 μm) for a 0.186 m ID,9.0 m high riser.Experiment results indicated that gas mixing could be well described by a two-dimensional dispersion model. Due to internals, fluid in HDCFB experienced violent roll flowing,and radial distribution of gas concentration was more uniform than in that free bed.The radial dispersion coefficient showed a value of 1000 cm ²·s ^-1 ,a one and a half order of magnitude larger than that in conventional HDCFB.