SO2 REMOVAL WITH COAL SCRUBBING

This project is based on an effective removal of sulfur dioxide from flue gas with coal as the scrubbing medium instead of lime, which is used in the conventional FGD processes. A laboratory study proves that coal scrubbing is an innovative technology that can be implemented into a commercial process in place of the conventional lime scrubbing flue gas desulfurization process. SO{sub 2} was removed from a gas stream using an apparatus, which consisted of a 1-liter stirred reactor immersed in a thermostated oil bath. The reactor contained 60 g of 35-65 mesh coal in 600 ml of water. The apparatus also had 2 bubblers connected to the outlet of the reactor, each containing 1500 ml of 1 molar NaOH solution. The flow rate of the gas was 30 ml/sec, temperature was varied from 21 C to 73 C. Oxygen concentration ranged from 3 to 20% while SO{sub 2} concentration, from 500 to 2000 ppm. SO{sub 2} recovery was determined by analyzing SO{sub 2} concentration in the liquid samples taken from the bubblers. The samples taken from the reactor were analyzed for iron concentrations, which were then used to calculate fractions of coal pyrite leached. It was found that SO{sub 2} removal was highly temperature sensitive, giving 13.1% recovery at 21 C and 99.2% recovery at 73 C after 4 hours. The removal of SO{sub 2} was accomplished by the catalysis of iron that was produced by leaching of coal pyrite with combination of SO{sub 2} and O{sub 2}. This leaching reaction was found to be controlled by chemical reaction with apparent activation energy of 11.6 kcal/mole. SO{sub 2} removal increased with increasing O{sub 2} concentration up to 10% and leveled off upon further increase. The effect of SO{sub 2} concentration on its removal was minimal