At present time, the best combustion tecnology for burning the low grade coals in the fluidized bed combustion tecnology. In the fluidized bed combustion systems, which based on the combustion of coal particles in a fluidized space, the fundamental combustion and adsorbtion of SO2 and NOx can easily be realized. In the experimental studies, Kutahya Tuncbilek Lignite was used as fuel, silica sand and ash mixture was used as bed material, limestone from Goynilk was used as adsorbent. For the combustion system particle size of coal and limestone were calculated employing the cumulative method and optimum particle sizes for the system were determined. Adding limestone to the coal, effect of particle size on the emission behaviour was investigated. Separately optimum operating conditions were determined on the basis of pollutant emissions for different coal and adsorbent properties. These conditions are described as regions there the combustion performance is not hindered and there the efficiencies in combustion and SO2 adsorption are kept high.