Experimental and modelling study of ammonia-based FGD scrubbers

In this work, we propose an experimental and modelling study to define the mass-transfer aspects of SO2 absorption in ammonia (NH3) aqueous solution, also accounting for the kinetics of the chemical reaction by determining the Enhancement factors (EL) of the reactive absorption. The Enhancement factor (EL) for the overall SO2 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-mth, nth-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 %.