In this work the simulation of a wet Rue gas desulfurization (FGD) unit with spray tower of a power plant is presented aiming at an efficient follow-up and the optimization of the FGD system operation The dynamic model developed to simulate the performance of the system has been validated with operation data collected over a long period of time All the partaking physical and chemical processes like the limestone dissolution the crystallization of calcium sulfite and gypsum and the oxidation of sulfite ions have been taken Into account for the development of the simulation model while the gas absorption by the liquid droplets was based on the two-film theory The effect of the mean diameter of the slurry droplets on the performance of the system was examined as it was used as an index factor of the normal operation of the system The operation limits of the system were investigated on the basis of the model developed It is concluded that the model is capable of simulating the system for significantly different SO2 loads and that the absorption rate of SO2 is strongly affected by the liquid dispersion in the tower (C) 2010 Elsevier B V All rights reserved