导流筒直径对气升式环流反应器流动的影响和放大研究

Study on Effect of Draft Tube Diameter on the Hydrodynamics and Scale-up in an Airlift Loop Reactor

使用欧拉-欧拉双流体模型考察了重油-氢气体系在温度703.15K和压力11 MPa下,导流筒直径对气升式环流反应器内气、液两相流动的影响和放大规律,为悬浮床工业装置提供理论指导。模拟结果表明,导流筒直径过大或者过小都会造成气含率和环流液速最大值沿径向出现一定偏移。当导流筒直径与反应器外筒直径之比(D_i/D_o)为0.70时,反应器内流动性能达到最佳。反应器体积较小时,D_i/D_o对反应器内流动改变不大;在放大过程中,整体气含率随着D_i/D_o增加先增加后趋于稳定,整体环流液速先增加后减小。对体积为23.03m^3的环流反应器来说,D_i/D_o为0.75时流动性能较好;当反应器体积进一步放大至109.42m^3和208.42m^3时,流动特性在D_i/D_o为0.70时更好;放大过程中D_i/D_o最优区间出现一定的"左移"现象。

Euler-Euler two flow model was applied to investigate the effects of nozzle diameter and nozzle position on the hydrodynamics in the airlift loop reactor to provide theoretical guidance for suspension bed industrial equipment with the oil-hydrogen system under the conditions of temperture 703. 15 K and pressure 11 MPa. The simulation results showed that there appeared a radial deviation for the maximum of gas holdup and liquid circulation velocity when the diversion tube diameter was too big or too small. The flow performance was better when the ratio of diversion tube diameter to reactor diameter （Di/D0 ） was 0.70. For small reactor volume, the flow characteristic changed little along with the change of Di/L）.. In the process of amplification, the overall gas holdup increased little after the first increase with the increase of L〉i/L〉0, while liquid circulation velocity showed a trend of decrease after first increase. For loop reactor volume of 23. 03 m3 , good floAv properties achieved at Di/D.of 0. 75 , Avhile the optimal Di/D.Avas 0. 70 for loop reactor volume of 109. 42 m3and 208. 42 m^3. The optimal interval of Di/Doappeared “the left” phenomenon in the amplification.