CFD Study on Scale-Up of a Nonstaggered Circular Slotted Plate Air-Pulsed Column: Insights into Axial Dispersion

A 2D axisymmetric CFD model is developed to estimate the continuous-phase Peclet number (Pe) in a pulsed nonstaggered circular slotted plate column (PNCSPC). An Euler–Euler two-fluid monodispersed model is used. The standard (mixture level) k−ε model is used to model the turbulence. The coupled species transport equation is used to evaluate Pe in the continuous phase. The model is validated using the reported experimental data on Pe in a pulsed disc and doughnut column (PDDC) with an average absolute relative error (AARE) of 2.64%. Thereafter, the model is used to predict the effect of different operating parameters, namely continuous, dispersed, and pulsing velocities, on Pe in a PNCSPC. An increase in the pulsing velocity from 0.0222 to 0.0389 m/s reduces Pe from 9.08 to 8.81 (a reduction of 2.97%). An increase in the continuous-phase velocity from 0.0031 to 0.0067 m/s reduces Pe from 9.09 to 8.9 (a drop of 2.1%). Similarly, Pe decreases from 9.08 to 8.96 (a drop of 1.32%) as the dispersed-phase velocity is increased from 0.0042 to 0.0075 m/s. Furthermore, a one-on-one comparison of Pe of PNCSPC and PDDC is also reported. Under similar conditions, Pe in PDDC is 14.64% lower vis-à-vis PNCSPC. Finally, the model is used to study the effect of scale-up of PNCSPC on dispersed-phase holdup and Pe. Two scale-up approaches, keeping the number of slots constant and keeping the slot width constant, are evaluated. The second approach (constant slot width) is found to be better as Pe values are ∼36.9% higher than the first approach (constant number of slots).