سال انتشار: ۱۳۸۶
محل انتشار: پنجمین کنگره بین المللی مهندسی شیمی
تعداد صفحات: ۸
Behin – Department of Chemical Engineering, Faculty of Eng., Razi University, Kermanshah, IRAN
Kompany – Department of Chemical Engineering, Faculty of Eng., Razi University, Kermanshah, IRAN
The liquid mixing time, circulation time, and circulation velocity in the riser and two downcomers of a modified airlift loop reactor with double draft tubes were investigated. The mixing parameters found with using tracer technique in a column of 18.5cm in diameter, 90cm in height, and two concentric draft tubes of 14 and 8.5cm in diameter and 82cm in height respectively. The tracer injection method and impulse response was used to find the mixing parameters. The mixing times decreased with superficial gas velocity, with a power correlation. The exponent values were -0.194, -0.197 and -0.164 for riser, inner and outer downcomers respectively, which shows the lower values of mixing time for double draft-tube configuration compared to conventional ALR. The mixing parameters and circulation velocity are compared for different part of the column. For all injections points, the similar results were achieved in all sections. An ascending trend of circulation velocity with the increase of superficial gas velocity was seen. The circulation velocity in riser, inner and outer downcomers varied with an exponent of 0.235, 0.145, and 0.177 with superficial gas velocity respectively. The liquid circulation velocity in the outer downcomer showed higher values, because of higher wall effects and losses, than the inner one.