提升管反应器不同喷嘴角度的气固流动特性研究

在大型循环流化床冷态模拟试验装置上对喷嘴与提升管竖直方向的不同夹角进行了考察。对3种不同夹角结构下的颗粒浓度轴径向分布、瞬时颗粒浓度信号以及概率密度进行了分析研究,结果表明:在预提升段和输送段3种结构并无明显差别,颗粒浓度以及瞬时信号波动的差别主要集中在喷嘴上方附近区域;相比于传统等径提升管而言,变径提升管内床层颗粒浓度增加,颗粒浓度分布更加均匀,颗粒浓度梯度减小,有利于气固两相的混合与接触;在变径提升管内,随着喷嘴角度的增大,气体在整个截面上的扩散速度增加,径向分布更加均匀,气固分离现象得到了有效抑制,气固湍动剧烈,接触效率较高。

STUDY ON GAS-SOLID FLOW CHARACTERISTICS IN RISER REACTOR WITH DIFFERENT NOZZLE ANGLES

The effect of angles between nozzle and riser in vertical direction on the flow properties was investigated in a large CFB cold simulation test device. The axial and radial distributions of particle concentration，instantaneous particle concentration signal and probability density analysis in three angles cases were investigated. The results showed that in the pre-lift section and the conveying section，no significant difference between the three cases was found，and the difference existed mainly in the vicinity zone above the nozzle; compared with the traditional equal-diameter riser，the solid-holdup of the bed in the variable-diameter riser increased，the particle distribution was more uniform, but the particle concentration gradient reduced，which is beneficial to the mixing and contact of the gas-solid two phases. As the nozzle angle increased，the diffusion velocity of the gas increased over the entire section，the radial distribution was more uniform，the gas-solid separation phenomenon was effectively suppressed，the gas-solid turbulence was more severe，resulting in more effective contact in the variable-diameter riser.