New insight and experimental study of ineffective void in hydrodynamic performance of countercurrent-flow packing column

Extensive experimental research and hydrodynamic models have been proposed to guide the design of superior packings. However, most research has concentrated on the effective void (ε − H) of packing while ignoring the ineffective void (ε − H − H_L), which causes discrepancies in hydrodynamic performance compared to actual observations. This study evaluated the hydrodynamic performance under diverse conditions considering the liquid holdup (H), pressure drop (ΔP), and gas flooding velocity (u_f). A novel approach to hydrodynamic model construction is introduced by incorporating an ineffective void. The results indicate that at a constant hold-up area, liquid flow (L) and viscosity (μ) significantly influence liquid hold up, moderated by the gas velocity in the flooding area. The pressure drop rises as the viscosity, gas flow rate, and liquid flow rate increase. Notably, a considerable pressure drop initiates flooding at the bottom of the absorber. Elevated liquid flow rates and viscosities correlate with higher ineffective void values (H_L) in the packing column. At low gas flow rates, the gas flow rate marginally affects H_L values. However, after the flooding point was achieved, the values of H_L rapidly increased as the gas flow rate increased. Moreover, a linear relationship emerges between the liquid holdup and H_L, as evidenced by the consistent variation in the liquid holdup and the F-factor. Utilizing the ineffective void yields a more accurate fit for the experimental data, reducing the average absolute relative deviation to 10.2%, 7.4%, and 10.8%, respectively.