Kinetics of CO<sub>2</sub> Absorption in Concentrated K<sub>2</sub>CO<sub>3</sub>/PZ Mixture Using a Wetted-Wall Column

Using a K<sub>2</sub>CO<sub>3</sub>/piperazine (PZ) mixture as a typical phase-change absorbent has promising applicability for carbon dioxide (CO<sub>2</sub>) capture in coal-fired power plants that would contribute to low energy consumption for solvent regeneration. In this study, the reaction rate of CO<sub>2</sub> with a concentrated K<sub>2</sub>CO<sub>3</sub>/PZ mixture was measured in a wetted-wall column. At a CO<sub>2</sub> loading close to saturation absorption, correlative physical parameters were calculated. The effects of operating conditions, including gas flow rate, slurry flow rate, PZ concentration, CO<sub>2</sub> loading, K<sub>2</sub>CO<sub>3</sub> mass fraction, and temperature, on the absorption rate of CO<sub>2</sub> were investigated. The results showed that the absorption rate was sensitive to the effects of the gas flow rate and CO<sub>2</sub> loading. The PZ concentration and K<sub>2</sub>CO<sub>3</sub> mass fraction also substantially influenced the CO<sub>2</sub> absorption rate. However, minor changes in the CO<sub>2</sub> absorption rate were observed when the slurry flow rate and temperature were increased. On the basis of a pseudo-first-order model, the absorption rate determined in this study was found to be controlled by mass transfer in both the gas film and the liquid film. The results can serve as a useful reference for designing CO<sub>2</sub> removal systems using K<sub>2</sub>CO<sub>3</sub>/PZ mixtures.