Pilot-scale Validation of the Modeling of NOx Reactive Absorption Process Using Aqueous Solutions Containing Nitric Acid and Hydrogen Peroxide

Abstract

NOx are harmful pollutants emitted by many industries and must be removed before the gases are released into the atmosphere. Among the various techniques used for NOx removal, reactive absorption by hydrogen peroxide in a packed column has the advantage of being able to transform NOx into nitric acid which can be recycled and reused in the plants. This work aimed at modeling the NOx absorption by means of aqueous solutions of hydrogen peroxide and nitric acid, applied in a packed column operating under different representative conditions. The model established using the Aspen software considers the equilibrium and the kinetics of the reactions taking place both in the gas phase and in the liquid phase as well as the thermodynamic properties of the chemical (molecular and ionic) components estimated using the Electrolyte NRTL model. It allows predicting NOx absorption performances in terms of efficiency and selectivity. The model was validated by comparing simulation results with experimental ones obtained in a pilot-scale absorption column and published previously. The predicted values are in satisfactory agreement with the experimental data showing a deviation between 5 and 8%. Therefore, the model developed in this work could be advantageously used to design industrial-scale reactive NOx absorption columns.