Experimental and modelling study of ammonia-based FGD scrubbers

• The ammonia-based absorption is characterized by a very fast gas–liquid reaction; • The absorption rate is correctly described by a pseudo second-order kinetic equation; • The kinetic model is able to predict absorption column data from the literature. In this work, we propose an experimental and modelling study to define the mass-transfer aspects of SO 2 absorption in ammonia (NH 3 ) aqueous solution, also accounting for the kinetics of the chemical reaction by determining the Enhancement factors (E L ) of the reactive absorption. The Enhancement factor (E L ) for the overall SO 2 chemical absorption reaction is evaluated in a falling-film absorber under different experimental conditions and it is correlated to the Hatta number (Ha) by means of the Danckwerts equation (a pseudo-m th , n th -order non-reversible reaction kinetic), valid for very fast gas–liquid reactions, and finding the model parameters from best fitting of the experimental data. Finally, the ammonia-based FGD model consisting of the combined use of the Danckwerts equation with mass transfer coefficients and thermodynamic equilibrium correlations is used to predict the performance of reactive absorption in a lab-scale packed column whose data are reported in the literature, providing a maximum error prediction of ±25 %.