This work presents the numerical results on reduction of sulfur emission from combustion of heavy oil in a combustion chamber. One of the most practical methods for sulfur emission reduction is flue gas desulfurization (FGD). In this study various FGD absorbers have been studied by means of numerical simulations. The flow is assumed turbulent two-phase flow while gas is the continuous and droplets form the dispersed phase. Heavy oil with considerable sulfur contents has been used as the fuel. The results show that, the Na-based absorbers are more efficient than the calcium-based absorbers. In addition, it is found that the efficiency of Sodium bicarbonate (NaHCO_3) is about 96% while the efficiency of calcium oxide (CaO) is about 74%. The efficiency of the Na-based absorbers is higher than the Ca-based absorbers due to the low density of Na-based absorbers. The low density of Na-based absorbers leads to a better dispersion of the absorber particles. The second reason for higher efficiency Na-based absorber is lower activation energy compared with Ca-based absorber. In addition, the mixing of Na-based absorbers dominates the mixing of the Ca-based absorbers. Thus, the reaction efficiency and kinetics of Na-based absorbers dominate in the same conditions with Ca-based absorbers.