Prediction of uncatalysed calcium bisulphite oxidation under operating conditions relevant to wet flue gas desulphurization plants

Wet limestone scrubbing is the most common flue gas desulphurization (FGD) process. In this process, oxidation of calcium bisulphite plays a major role both by determining the dewatering properties of the obtained sludge and the production of gypsum of high quality. In order to contribute to the simulation of the wet limestone FGD process, in the present paper a comprehensive model for isothermal gas-liquid stirred tank reactors has been used. Based on the assumption that the reactions are zeroth order with respect to gaseous reactants, the model requires appropriate physico-chemical parameters which are taken from the literature. The model was used to quantitatively interpret some literature experimental data concerning uncatalysed calcium bisulphite oxidation performed in a continuous stirred tank reactor. In particular, the model is capable of confidently predicting the transition from chemically to mass transfer controlled regime occurring when changing the operating conditions.