Liquid Distribution inside a Wet Scrubber using Computational Fluid Dynamics with an Euler-Lagrangian Approach
The two-phase flow structure inside an industrial scale wet scrubber composed of an industrial Venturi scrubber (throat diameter = 0.43 m) and a washing column (internal diameter =1.75 m, height = 6.45 m) was numerically simulated using a RANS approach. Turbulence was modeled by a standard k-ε model, with the two phase interaction provided by a two-way coupled Euler-Lagrangian approach, implemented in ANSYS CFX 16.0. Droplet breakup due to deformation, known as secondary atomization, was accounted for by using a Cascade and Atomization Breakup (CAB) model, selected according to a previous study, whereas droplet distribution at the injection was assumed as a Rosin-Rammler distribution, with mean diameter estimated from hollow-cone atomizer studies. Grid dependency and time step choice were also accessed in previous studies. Simulations carried out for 5 kg/s gas flow rate and three different liquid flow rates in the washing column (2.8, 5.6 and 11.1 kg/s) indicated the effect of this variable on the liquid distribution profile throughout the equipment, which will be visualized in the figures of the paper. For lower liquid flow rates, liquid depleted regions were observed, which can reduce the gas cleaning efficiency. Higher liquid flow rates resulted in smaller droplets, which correspond to larger liquid-gas specific interface areas, a condition that favors mass transfer, and increase the collection efficiency of the scrubber.