Influence of particles on mass transfer performance for CO2 absorption using K2CO3 solution in a random θ-ring packed column

Abstract

The buildup of uncaptured fly ash particles from wet flue gas desulfurization (WFGD) system in post-combustion CO2 capture processes is an important issue in existing coal-fired power plants. A self-designed lab-scale packed column filled with θ-ring packing was used to investigate the influence of fly ash particles on the volumetric overall mass-transfer coefficient KGav using K2CO3 absorbent. The affecting laws of fly ash particles on the KGav were discussed under different operating conditions such as the solution temperature, the liquid-gas ratio L/G and the concentration of fly ash particles. The results showed that the effect of two types of fly ash particles on the outlet CO2 concentration mainly occurred at the early period of the experimental process, while the effect extent of the Inner Mongolia ash was larger than Nanjing ash. The solution temperature and the liquid-gas ratio had a significant role in promoting the KGav, but the presence of fly ash particles in K2CO3 solution markedly reduced the KGav. The influence of fly ash particles on the KGav was independent of its chemical compositions, but was related to the operating parameters. With the solution temperature increasing, the influence of fly ash particles on the KGav was weakened but, conversely, was increased with the liquid-gas ratio increasing. Change range of the KGav was smaller and finally reached a stable state as the fly ash particles concentration increases. The analysis results indicated that the influence of the ash particles was realized via changing the initial distribution of the absorption solution.