Optimization of a wet flue gas desulfurization scrubber through mathematical modeling of limestone dissolution experiments

Dissolution rates of two very pure limestone samples were measured experimentally by means of the pH-stat method under conditions where mechanical stirring did not affect the rates considerably. The experimental results were modeled mathematically by considering the surface areas of the particles changing dynamically through the reaction; moreover, a surface factor was introduced in order to account for the nonsphericity of the particles. The surface areas were measured by means of gas adsorption and by particle size distribution (laser diffraction). Liquid-phase concentrations were measured by inductively coupled plasma optical emission spectrometry, and surface compositions were measured by X-ray spectroscopy. Furthermore, scanning electron microscope images of the samples are presented. Subsequently, an optimization model of a scrubber was developed by using the intrinsic parameters of the samples, which were determined experimentally. The optimization results indicate that up to 34–50% of the power required for milling can be saved by milling to a coarser particle size than the commonly used size of 44 μm, depending on the sample type. The present model of the lab-scale experimental study and the optimization model can be employed to estimate the actual impact that using different types of raw material would have in the operation of a wet flue gas desulfurization scrubber.