Characteristic times for limestone particle dissolution in the production of gypsum from the wet flue gas desulphurisation process

Limestone dissolution plays a relevant role in determiningthe quality of the gypsum that can be obtained as abyproduct of the wet limestone flue gas desulfurizationprocess. In this work, the dissolution of limestone in anaqueous solution of SO:! is experimentally studied. Thedissolution rate in a fixed-bed reactor is measured atdifferent sulfur strengths of the solution and liquid-solidrelative velocities. The results are interpreted using amodel based on the film theory. It is shown that thethickness of the liquid film, and therefore the Sherwoodnumber, is a function of the Reynolds number, and acorrelation is proposed for this dependence. Using thecorrelation and the theoretical model proposed, someresults are obtained for the shrinking of a sphericallimestone particle as a function of time.