Kinetic behavior of potassium bicarbonate crystallization in a carbonate-based CO₂ absorption process

A carbonate-based CO₂ absorption process is currently under development that involves crystallizing potassium bicarbonate from a potassium carbonate/bicarbonate solution to form slurry used for stripping CO₂ at high pressure. Kinetics of the bicarbonate crystallization process was investigated using a laboratory mixed suspension, mixed product removal (MSMPR) reactor. Effects of the mean residence time, agitation speed, relative supersaturation level, crystallization temperature, and suspension density on nucleation and growth rates of the bicarbonate crystals were quantified. The observed crystal population density distribution featured a size-dependent growth pattern. A three-parameter kinetic model was used for bicarbonate crystallization, and model parameters were determined by fitting the experimental data. Crystallization kinetics was applied to perform a preliminary analysis of the crystallizer design for the carbonate-based CO₂ capture process.