The model of desorption of SO2 from sodium sulfite/bisulfite solution verified experimentally is given. The model consists of equations which describe the performance of a packed column working with a boiler and a condenser. The model analysis of the system is given over the wide range of operating parameters. The relation between two basic quantities describing the energy requirements of the system (SO2 content in a gas leaving the column) and the solvent regeneration (concentration of sodium sulfite leaving the boiler) is analysed.