内循环气升式反应器的操作特性与流体力学研究

Study on operation characteristics and fluid dynamics of internal loop air-lift reactor

气升式反应器在化工和环境等领域有着广泛的应用,准确预测反应器内气液两相流动与传质行为对于反应器的设计与放大十分重要。论文通过建立稳态条件下内循环气升式反应器内的气液两相流动模型,实现对循环液速vL、气含率εG与气相循环比β等重要流体力学参数的求解。当提升管高度分别为2和6 m时,模型参数c0取0.65,模型计算的反应器内的vL与εG值与实验结果的相对平均误差小于6.2%。在此基础上,进一步考察了提升管高度H对平均循环液速和平均气含率的影响规律。模拟结果表明,随着提升管高度的增加,循环推动力增加,循环液速上升,平均气含率略有下降。下降管和提升管内气含率比α与反应器尺寸和表观气速等操作条件相关,取值范围为0.72~0.80。

Air-lift reactors are widely used in the field of chemical and environment engineering,and it is of vital significance to accurately predict air-liquid two phase circulation and mass transfer behavior.In this study,a gas-liquid two phase flow model of internal loop air-lift reactor under steady state was proposed to calculate a series of fluid dynamic parameters,including circulation velocity vL,gas holdupεG,and ratio of gas circulationβ.Circulation velocity vL and gas holdupεG was obtained via experiments in risers of 2 m and 6 m long and when the model parameter c0 was 0.65,the relative average error between model calculation and experimental results for vL andεG was less than 6.2%.The influence law of riser height on liquid circulation velocity and gas holdup was investigated.The results showed that with the increase of riser height,the circulating driving force increases,the circulating liquid velocity increased,and the average gas holdup decreased slightly.It was found that the ratio of gas holdup in the downcomer and riser related to operation parameters,such as reactor’s size an apparent gas velocity,and varied between 0.72 and 0.80.