Effect of flow patterns/regimes on CO2 capture using K2CO3 solid sorbent in fluidized bed/circulating fluidized bed

CO2 capture from flue gas using a potassium carbonate supported on alumina (K2CO3/Al2O3) solid sorbent was investigated in different flow patterns/regimes in fluidized bed/semi circulating fluidized bed made from glass reactor at low temperature 60 °C. The semi-circulating fluidized bed reactor has 0.025 m of inner diameter and 0.80 m of height. The CO2 capture capacity were measured in the presence of H2O for five different flow patterns/regimes including fixed bed, multiple bubbling, slugging, turbulent and fast fluidization. It can be found that the fixed bed and multiple-bubbling bed could adsorb all CO2 in flue gas (CO2 removal fraction = 1) during 17 min and 10 min, respectively. The slugging, turbulent and fast fluidization could not remove 100% of CO2 in feed gas. Maximum CO2 removal fractions for slugging, turbulent and fast fluidization were 0.98, 0.94 and 0.72, respectively. However, the turbulent regime provided the best CO2 capture capacity at about 90% of stoichiometric theoretical value. The CO2 capture capacity for the multiple-bubbling and fast fluidization regimes were lower with about 66–72% of stoichiometric theoretical value. The fixed bed and slugging regimes provided the poorest CO2 capture capacity at about 53–60% of stoichiometric theoretical value. From all the obtained results, the CO2 capture capacity of the sorbent changed dramatically depending on the flow patterns/regimes in fluidized bed/circulating fluidized bed.

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► The CO2 capture capacity depends on flow patterns/regime in fluidization systems.
► The CO2 removal breakthrough shape was different between the flow pattern/regimes.
► The fixed bed and slugging flow patters/regimes showed poor CO2 capture capacity.
► The turbulent fluidization regime provided most promising CO2 capture capacity.