Bubble deformation characteristics and the effect on particle removal efficiency in wet scrubbers

Single-bubble formation and rise are fundamental to the prediction of decontamination factors (DF) under the complex hydrodynamics of bubble flow and the gas–liquid flow pattern. However, bubbles in the water for particle control are not always perfectly spherical or ellipsoidal. To date, studies of bubble washing for particle removal have mainly focused on models with simple spherical and ellipsoidal shapes or the impact of operating parameters on removal efficiency. No attempt has been reported in the literature to determine the effect of bubble shape on particle removal efficiency. An investigation of the influence of bubble deformation during the bubble rising period was carried out using a high-speed camera and image analysis techniques to study the bubble shape. The experimental results show that the deformation of a bubble is directly correlated with its rising velocity, rising tail, equivalent radius and residence time. These parameters are generally estimated using ideal values, which are crucial for the accuracy of efficiency calculation model results. SPARC-90 code is an important scrubbing modelling tool developed for prediction of bubble hydrodynamics and the corresponding aerosol retention behavior. The potential for particle removal with a single rising deformed bubble was recently determined using a prototype of the SPARC-90 code with the experimental results. The results of SPARC-90 calculations with various equivalent diameters obtained in this experiment have provided more accurate decontamination factors compared to those obtained with a round bubble and a default bubble diameter.