Modelling of absorption of nitrous waste gases

Absorption of nitrogen oxides (NOX) is an important branch of waste gas treatment. Nitrogen oxides are present in the waste gases of a number of processes like fertilizer production, nitration of organic compounds or combustion processes in power plants. From the ecological and economic points of view it is desirable to combine the removal of nitrogen oxides from the waste gases with the production of an important intermediate product, namely nitric acid. NOX absorption into aqueous solutions (sour NOX absorption) is a very complex process due to the presence of simultaneous heat and mass transfer coupled with chemical reaction. Studies of this process which have been published up to now are based on rather simplified theoretical models. In this paper a computer aided tool is developed for the optimization and design of NOX absorption in countercurrent columns. This tool is founded on the rate-based approach and accounts for simultaneous heat and mass transfer in multicomponent systems combined with chemical reactions. This tool has been verified with industrial experimental data.