高径比和底隙高度对内循环反应器性能的影响

Effects of height to diameter ratio and height of base slot on the performance of internal airlift loop reactors

建立了内循环反应器试验装置,综合研究了内循环反应器最重要的结构参数(高径比和底隙高度)对反应器主要性能参数(液体循环流速、总平均气含率、液体混合时间和体积氧传质系数)的影响。研究发现,表观气速存在一个不利于液体循环的过渡区,在该过渡区随表观气速增加,液体循环流速增大缓慢,甚至减小,但较高的底隙高度会减弱这种效应;在一定的表观气速和高径比下,随底隙高度增加,液体混合时间、总平均气含率先增大后减小;在一定的表观气速和底隙高度下,液体混合时间随着高径比增大而增大,体积氧传质系数、总平均气含率随高径比增加而减小。

An internal airlift loop reactor was built for study of the air-water two-phase system. The liquid circulation time and the mixing time were determined by the pulse conductivity method and the overall average gas holdup by the volume expansion approach. The effects of height to diameter ratio（Hr/D）and of the downeomer on liquid circulation velocity, overall average gas holdup, special mixing time, and mass transfer coefficient of dissolved oxygen were investigated. Anlysis of the data indicated that a special inteval of superficial gas velocity was existed, the increasing uperficial gas velocity is unfavourable to Liquid circulation in this inteval, a larger height of base slot would reduce this adverse effect. At specific superficial gas velocity and the height to diameter ratio the overall average gas holdup, liquid mixing time increased at first to the maximum,and then decreased gradually with the raise of the; At specific superficial gas velocity and height of base slot of the downcomer liquid mixing time increased with the raise of the height to diameter ratio（Hr/D）, mass transfer coefficient of dissolved oxygen and overall average gas holdup decreased gradually with increase of the height to diameter ratio（Hr/D）.