In this paper, a concise model for wet limestone-gypsum flue gas desulfurization system with spray tower has been presented, aiming at the prediction of the absorption height in a spray tower. The equations of droplet motion and mass balance were incorporated and developed to simulate the droplet movement, distribution and mass transfer of SO2 in the absorption section. The calculation results were in good agreement with the plant values of the absorption height. The influences of operating parameters on the absorption height were analyzed. The results show that absorption height declines with increasing liquid-gas ratio and pH value of the slurry, and increases with increasing droplet diameter, gas flow rate, gas temperature, inlet SO2 concentration and absorption efficiency, respectively. As the most sensitive parameter, the droplet diameter is crucial for the good prediction of absorption height This model can provide engineering guidance to design a spray tower absorber. (C) 2014 Elsevier B.V. All rights reserved.