THEORETICAL PREDICTION OF STATIC LIQUID HOLDUP IN TRICKLE-BED REACTORS AND COMPARISON WITH EXPERIMENTAL RESULTS

Liquid holdup is an important performance parameter for designing and operating a trickle bed reactor. So far, no theoretically sound prediction for static holdup is available. In this work, the fundamental principles of thermodynamics and hydrostatics were used to establish a theoretical model A third-order ordinary differential equation was formulated for an axisymmetric liquid pendular ring at contacting points between spherical particles. A thermodynamic criterion of minimum internal energy is proposed to select the unique and most probable amount of liquid held in a single pendular ring. Averaged over the orientation of the pendular rings and the volume of the trickle bed, its static liquid holdup can be predicted. The measurements of static holdup was determined by subtracting the dynamic holdup (by drainage method) from the total holdup (by tracer experiments). The theoretical prediction compared quite satisfactorily with the experimental data.