Numerical Simulation of Spray Towers

Spray absorbers are widely used to remove SO2 from flue gases of large coal-fired power-plants or garbage incinerators. In such scrubbers the SO2 is absorbed by a suspension of water and limestone. The suspension is dispersed by nozzles to obtain a large interfacial area. There exists a great diversity of designs for spray scrubbers. Towers with cylindrical or square cross section are used. The inlet gas stream is directed radially or tangentially inward and is transported in counter-current or co-current motion with respect to the spray droplets. The nozzles are arranged at different spray bank levels. Full cone or hollow cone sprays with various opening angles can be applied. In the experimental investigation radial gas velocity profiles where measured by Laser Doppler anemometry (LDA) at single phase flow and two phase flow operation. It is demonstrated that the CFD simulation in a design optimisation procedure effectively can be used to correct gas and spray maldistribution effects. This goal is reached by altering the nozzle array configuration and combining nozzles with different spray characteristics.