Modelling of the Lenzing SO2 recovery process and validation with plant data

Mass balances were performed for the recovery absorption stages of a magnesium bisulphite pulping process in order to obtain accurate basic data for further process simulation. Data for the main components (liquid flows, sulphur and magnesium oxide) were obtained at three different power levels of the downstream recovery boiler. Based on these results, single absorption stages were simulated with a commercial modelling package. The results of the mass balance and the results of the simulation of single absorption stages are compared. Furthermore, results simulated with the new model of the whole absorption recovery system are shown and problems, which appeared during the calculation runs, are described.