MODEL OF OXYGEN ABSORPTION INTO CALCIUM SULFITE SOLUTIONS

Wet limestone scrubbing is the most common flue gas desulfurization pr ocess, and in this process sulfite oxidation plays a major role determ ining the dewatering properties of the sludge produced and leading to the production of gypsum of high quality. A literature analysis showed that the results obtained for sulfite oxidation under homogeneous con ditions are relatively easily interpreted, while the results relative to heterogeneous reaction conditions (i.e. conditions in which gaseous oxygen and a sulfurous solution are brought in contact) are much more difficult to interpret, owing to the interaction between mass transfe r and chemical reaction, In this work a model is proposed to describe the interaction between oxygen absorption and the oxidation reaction u nder heterogeneous conditions, which takes into account the peculiar c haracteristics of absorption with zero order reaction, A kinetic equat ion of order zero in dissolved O-2,3/2 in HSO3- and 3/2 in the catalys t concentration was used to match experimental results presented in th e literature and model results, Integration of the model equations led to evaluation of the oxygen absorption rate as a function of the cata lyst concentration together with the concentration profiles in the liq uid film for the different species. (C) 1997 Elsevier Science S.A.