The Dual Drive Stirred Tank Experimental Study Of Coal Slurry Flue Gas Desulfurization

Coal slurry flue gas desulphurization (FGD) is based on aqueous catalytic oxidation. SO2 is removed from flue gas through the reaction, and the content of sulfur in coal pyrite is reduced at the same time. In this study, a double stirred tank is used as the main laboratory equipment, the simulated flue gas is mixed with SO2, N2 and O2 according to a certain proportion, different gas and liquid phase conditions are studied for the influence on coal slurry FGD and leaching rate of pyrite in aqueous.When the gas velocity varied from 2.5ml/s to 5.7ml/s, the average SO2 absorption rate, leaching rate of iron and the apparent rate constant enhanced as the gas velocity increased. But as the retention time in the reactor became shorter when the gas velocity increased, the SO2 removal efficiency decreased. When the SO2 concentration varied from 800×10-6 to 3500×10-6, the average SO2 absorption rate and leaching rate of iron enhanced as the SO2 concentration increased. While the the apparent rate constant became bigger as the SO2 concentration increased when the SO2 concentration below 1500×10-6, and the change became slightly when the SO2 concentration above 1500×10-6. The SO2 removal efficiency decreased as the SO2 concentration increased when the other conditions were the same. When the O2 concentration varied from 3% to 20%, the average SO2 absorption rate became faster as the O2 concentration increased, and the apparent rate constant increased when the O2 concentration was low, while when the O2 concentration reached a higher level,the apparent rate constant changed not obviously.The SO2 removal efficiency increased when the O2 concentration increased.When the temperature varied from 25℃to 6℃, the average SO2 absorption rate decreased slightly as the temperature increased, but the leaching rate of iron and the apparent rate constant increased obviously when the temperature was higher. When the liquid-solid ratio varied from 10:1 to 80:1, the average SO2 absorption rate decreased as the liquid-solid ratio increased, the leaching rate of iron and the apparent rate constant increased as the liquid-solid ratio increased. When the particle size of coal varied from 65μm to 150μm, the smaller particle size is benefit for the leaching rate of iron and the apparent rate constant. The SO2 removal efficiency was better when the particle size of coal was smaller. The leaching form of the coal pyrite fits the shrinking core model well.