CFD modeling of droplet dispersion in a Venturi scrubber

Abstract

A modified two-dimensional mathematical model was developed to simulate droplet dispersion through a cylindrical Venturi scrubber based on Eulerian approach. Droplet concentration distribution was evaluated using the equation of mass balance of droplets. The velocity field of gas flow was determined using k– ɛ turbulence model. Droplet velocity distribution was calculated by means of the equations derived using momentum balance of droplets. Gas eddy diffusivity which has already been determined based on constant Peclet number in the previous models was calculated using turbulent characteristic velocity and length. Fathikalajahi et al. approach was applied to calculate eddy diffusivity of droplets (Fathikalajahi et al., 1995 [7]). The mean diameter of generated droplets was determined by Boll's correlation (Boll et al., 1974 [16]). Rosin–Rammler distribution function was used to take into account the distribution of droplet size. In order to verify the results of the new model a set of experiments was performed on a pilot-scale cylindrical Venturi scrubber with axial liquid injection. During these experiments, the flow rates of liquid droplets were measured at several points of throat section end from center line to the wall. The comparison between the results and experimental data showed that the droplet concentration distribution predicted using the present model were in better agreement with experimental data than that predicted using the previous models which were based on constant Peclet number. Also it was concluded the distribution parameter of Rosin–Rammler function, n RR , could not be considered as a constant parameter and it depended on the L/ G (gas to liquid flow rate ratio) and V g0 (gas throat velocity).