Fluidisation behaviour and wall effects of cohesive hydrotalcite powder in a micro-fluidised bed
Awad Alamri, Jonathan McDonough, Vladimir Živković
Abstract
Hydrotalcites are a promising candidate for capturing CO2, but their strong inter-particle forces produce significant agglomeration and poor fluidisation quality in micro-fluidised bed technology. Therefore, in this study we performed detailed hydrodynamic experiments using the pressure drop characterisation approach to identify viable MFBR designs and operating conditions for these Geldart C powders. Our results show that a simple combination of pre-sieving the particles to remove the fines (retaining sizes of >53 μm; density of 2 g/cm3) and pre-fluidisation drastically improved the fluidisation quality. Here the pressure overshoot prior to fluidisation and slugging behaviour were minimised. Additionally, mixing a secondary inert Geldart A particle to the hydrotalcite powder (silica; 93 ± 10 μm; density of 2.65 g/cm3) also reduced the presence of slugging and pressure overshoot. These treatments were valid in three 3D-printed MFBRs (bed diameters of Dt = 10–15 mm) at all bed heights tested (Hs/Dt = 1–3).