CHARACTERISTIC TIMES FOR LIMESTONE PARTICLE DISSOLUTION IN THE PRODUCTION OF GYPSUM FROM THE WET FLUE-GAS DESULFURIZATION PROCESS

Limestone dissolution plays a relevant role in determining the quality of the gypsum that can be obtained as a byproduct of the wet limestone flue gas desulfurization process. In this work, the dissolution of limestone in an aqueous solution of SO2 is experimentally studied. The dissolution rate in a fixed-bed reactor is measured at different sulfur strengths of the solution and liquid-solid relative velocities. The results are interpreted using a model based on the film theory. It is shown that the thickness of the liquid film, and therefore the Sherwood number, is a function of the Reynolds number, and a correlation is proposed for this dependence. Using the correlation and the theoretical model proposed, some results are obtained for the shrinking of a spherical limestone particle as a function of time.