Comparative Study of Sorbents for Spray Dry Scrubbing of SO₂ from Flue Gases

This study presents the findings of an investigationinvolvingthe absorption of SO2 from flue gases, using three differentsorbents, in a spray dryer. Experimentation involved the evaluationof three sorbents, i.e., hydrated lime (Ca[OH](2)), limestone(CaCO3), and trona (Na2CO3 & BULL;NaHCO3 & BULL;2H(2)O), and their relevant properties, forflue gas desulfurization by spray dry scrubbing. Experiments wereconducted to explore the effects of spray characteristics in the spraydrying scrubber on SO2 removal efficiency using the selectedsorbents. The ranges of various operating parameters were considered,including the stoichiometric molar ratio of (1.0-2.5), theinlet gas phase temperature of (120-180 & DEG;C), and an inletSO(2) concentration of 1000 ppm. The use of trona gave betterSO(2) removal characteristics; a high SO2 removalefficiency of 94% was recorded at an inlet gas phase temperature of120 & DEG;C and a stoichiometric molar ratio of 1.5. Under the sameoperating conditions, Ca[OH](2) and CaCO3 gave82 and 76% SO2 removal efficiency, respectively. Analysisof the desulfurization products by X-ray fluorescence (XRF) and Fouriertransform infrared (FTIR) spectroscopy revealed the presence of CaSO3/Na2SO3, a product of the semidry desulfurizationreaction. A significant proportion of unreacted sorbent was observedwhen Ca[OH](2) and CaCO3 sorbents were used ata stoichiometric ratio of 2.0. Trona also gave the highest degreeof conversion (96%) at a stoichiometric molar ratio of 1.0. Ca[OH](2) and CaCO3 gave 63 and 59%, respectively, underthe same operating conditions.