The CFD simulation based on the Eulerian-Eulerian model has been utilized to a small-scale Flue Gas Desulfurization (FGD) tower with perforated sieve trays. Most of the relevant studies have focused on the flow structures without the consideration of the chemical effects. In order to study the interactions between the flow structure and chemical reaction, the species transport equations of the chemical reactions have been implemented in the present study.& para;& para;The numerical investigation of this study includes the liquid phase distributions, streamlines of the gas phase, chemical source term, and mass fraction of SO2 gas. The complex vortical structure due to the implement of the sieve trays results in a sufficient large two-phase contact area. It also increases the number of times that the gas phase interacts with the liquid layer above the sieve trays and enhances flow mixing between regions of intense and weak chemical reactions. Correspondingly, the sieve trays can improve the SO2 removal efficiency. This study can help to carry out the numerical based optimal design of the full-scale tower in the future. (C) 2017 Elsevier Ltd. All rights reserved.