Hydrodynamics of bubbling fluidized bed for adsorption of CO 2 with KOH/K 2 CO 3

The aim of this study is to assess the performance of carbon dioxide (CO 2 ) capture in a bubbling fluidized bed using a proper adsorbent. A mixture of potassium hydroxide (KOH) and potassium carbonate (K 2 CO 3 ) adsorbents was used as bed materials, which provide proper kinetic and fluidization behaviours. The adsorbents consisted of two different mean particle sizes: size 1 is composed of K 2 CO 3 with mean particle size of 335 μm and KOH with mean particle size of 197 μm; whereas, size 2 contained the K 2 CO 3 with mean particle size of 605 μm and KOH with mean particle size of 197 μm. The weight fraction of KOH in both sizes was 0.3 g/g (30 mass%). The pressure fluctuations of the bed were measured and characterized in a time domain. The effects of several hydrodynamic parameters (i.e., superficial gas velocity, aspect ratio of bed, and particle size distribution of the adsorbent mixture) on CO 2 adsorption were investigated. The results showed that the larger bubbles caused an improvement in solid mixing in the bed and consequently enhanced the CO 2 capture capacity. Fluidization of the adsorbents mixture with narrower distribution (size 1) led to the formation of larger bubbles and an improvement of mixing in the bed. Therefore, size 1 adsorbent exhibited a higher CO 2 capture capacity compared to a wider distribution of (size 2) adsorbent. Furthermore, the bubble size is increased with an increase in the aspect ratio of the bed leading to a better mixing in the bed.