SO2 REMOVAL FROM HOT FLUE-GASES BY LIME SUSPENSION SPRAY IN A TUBE REACTOR

A laboratory-scale "dry" scrubbing tube reactor was constructed to handle synthetic flue gas with flow rates up to 7 m3/h. Hydrated lime suspended in fine droplets of water was sprayed countercurrently to the hot flue gases. Parametric tests of the effects of the stoichiometric ratio, reactor inlet and outlet temperatures, gas composition, and gas flow rate on the SO2 and Ca(OH)2 conversions were made. The SO2 conversion was generally in the range of 75-85%. A substantial part of the SO2 conversion takes place in the spray region due to the high density of droplets and particles, high turbulence, high droplet surface area, and droplet flow pattern in this region. Lowering the reactor temperature profile results in competing effects which lead to an optimal temperature for high conversion. The presence of oxygen in the gas mixture does not affect the SO2 conversion. The CO2 in the gas mixture competes with SO2 for reaction with Ca(OH)2 and results in the reduction of the SO2 conversion by about 5%.