进气喷嘴位置对循环流化床反应器循环量的影响

EFFECT OF INLET NOZZLE POSITION ON SOLID FLUX IN CIRCULATING FLUIDIZED BED REACTOR

在高10.6m、内径100mm的循环流化床冷态模拟实验装置上研究了底部预提升气以及喷嘴进气量对循环流化床反应器循环量的影响,对比了3种不同喷嘴位置结构下系统循环量的变化情况以及提升管底部和喷嘴附近气固流动行为的差异,描述了预提升段内气体分布及流动结构。结果表明:预提升气和喷嘴进气是颗粒向上输送的重要推动力,随着喷嘴进气口高度的提高,预提升气对颗粒循环速率的作用效果愈加明显;对于喷嘴进气口位置最低的结构,其系统循环量、喷嘴附近颗粒浓度以及气固接触状况均优于其它结构;在提升管底部,气体多次形成逆流接触,内循环流动和局部涡流作用有效促进了颗粒沿径向混合,有利于颗粒循环量的提高。

Circulating fluidization,as an efficient and bubble-free contacting technology for gas and solid,is the research frontier of fluidization techniques.By a cold simulation apparatus with a riser of 10.6 mheight and inner diameter of 100 mm,the effect of volume of pre-lifting gas as well as inlet jet gas on solid flux in circulating fluidized bed was studied.Especially,a comparative study of the solid flux with inlet nozzle at different positions as well as the difference of gas-solid flow behavior between region in the bottom and adjacent to nozzles was conducted.The gas distribution and flow structures in pre-lifting section in riser were described.The results show that pre-lifting gas and jet injection gas are the two important driving forces in pushing particles upward in riser.With the increase of jet inlet height,the effect of pre-lifting gas on solid flux becomes more obvious;the lower nozzle position shows the better performance in overall solid flux,solid holdup as well as gas-solid contact in nozzle region;Multiple gas countercurrent contact along with internal circulation flow as well as local vortex in bottom region of riser promote effectively the radial particle mixing and solid flux.