Numerical simulation of particulate removal efficiency in venturi scrubber

Abstract

Coal power plants are used extensively worldwide for electricity production due to its cheap rate. The major demerit is its adverse affect on the environment through emissions. The particulates and pollutant gases are the major ones, emitted by coal power plants. Venturi scrubber is one of those technologies that assist in simultaneous removal of particulates and toxic gases. To correctly understand and design these equipments, it is necessary to visualize the fluid dynamics inside these devices. In this regard, a numerical simulation is performed in ANSYS-CFX by using Eulerian-Lagrangian method to estimate particulate collection efficiency in the venturi scrubber. The collection efficiency is investigated at different gas and water mass flow rates. The potassium oxide (K2O) particles of one micron size with 2.35 g/cm3 density is used in simulation. Droplet diameter is also calculated in simulation by means of Cascade Atomization Breakup (CAB) model. Proper selection of breakup regime for droplet deformation in CAB model is determined by calculation of gas Weber and Ohnesorge number. Grade efficiency is calculated for throat gas velocity of 32 m/s with liquid to gas ratio of 7 l/m3. The affect of liquid to gas ratio at specific throat gas velocities on particulates removal efficiency and droplets diameter are also examined. The results shows that the increase in particulates removal efficiency occurred by increasing gas mass flow rate and liquid to gas ratio at particular gas velocities. The decrease in droplet size is observed during accession in liquid to gas ratio. Particulate removal efficiency of 99 % can be achieved at higher gas mass flow rates due to high inertial impaction parameter.