提升管与气-固环流床层耦合反应器颗粒相循环比的模型及预测

引言Geldart A类颗粒气-固环流技术是一种利用气-液环流原理,并结合气-固聚式流化体系特点而开发的一种新型流态化技术1],具有气固接触效率高、传质传热性能好等优点,被广泛用于石油炼制领域中的催化裂化汽提器、提升管出口粗旋快分的预汽提器、外取热器、石油焦燃烧器和降烯烃反应器等装备中2]。

Model prediction for particles circulation flux ratio in coupled reactor with riser and gas-solids loop fluidized bed

A mathematical model predicting particles flux ratio between internal circulation and external circulation processed in a coupled reactor with gas-solids loop fluidized bed was established.In a wide range of operating conditions, particles circulation flux ratio was predicted, and the particles circulation ratio n_p=20 was determined as a criterion to analyze the particles mixing behavior in internal and external loops.The results showed that the calculated values basically agreed with experimental data, and the average relative error approached 15.35%.Particles circulation ratio increased with increasing superficial gas velocity in the draft tube, however decreased with increasing particles external circulation flux and opening rate of a lotus-shaped distributor, with the change in two stages, first fast and then slow.The transition points were U_g,d=0.50 m·s^-1, G_s,r=110 kg·m^-2·s^-1, and α=10% respectively.Under the operating conditions of riser superficial gas velocity U_g,r=10—21.17 m·s^-1, draft tube superficial gas velocity U_g,d=0.57—1.50 m·s^-1, particles external circulation flux G_s,r ≥110 kg·m^-2·s^-1, and distributor open rate α≥10%, the particles complete mixing status in the riser and the gas-solids loop bed reactor could be avoided.