Comparative Study of Sorbents for Spray Dry Scrubbing of SO 2 from Flue Gases

This study presents the findings of an investigation involving the absorption of SO from flue gases, using three different sorbents, in a spray dryer. Experimentation involved the evaluation of three sorbents, i.e., hydrated lime (Ca[OH] ), limestone (CaCO ), and trona (Na CO ·NaHCO ·2H O), and their relevant properties, for flue gas desulfurization by spray dry scrubbing. Experiments were conducted to explore the effects of spray characteristics in the spray drying scrubber on SO removal efficiency using the selected sorbents. The ranges of various operating parameters were considered, including the stoichiometric molar ratio of (1.0-2.5), the inlet gas phase temperature of (120-180 °C), and an inlet SO concentration of 1000 ppm. The use of trona gave better SO removal characteristics; a high SO removal efficiency of 94% was recorded at an inlet gas phase temperature of 120 °C and a stoichiometric molar ratio of 1.5. Under the same operating conditions, Ca[OH] and CaCO gave 82 and 76% SO removal efficiency, respectively. Analysis of the desulfurization products by X-ray fluorescence (XRF) and Fourier transform infrared (FTIR) spectroscopy revealed the presence of CaSO /Na SO , a product of the semidry desulfurization reaction. A significant proportion of unreacted sorbent was observed when Ca[OH] and CaCO sorbents were used at a stoichiometric ratio of 2.0. Trona also gave the highest degree of conversion (96%) at a stoichiometric molar ratio of 1.0. Ca[OH] and CaCO gave 63 and 59%, respectively, under the same operating conditions.