Hydrodynamics of Bubbling Fluidization

Dynamically structured fluidization: Oscillating the gas flow and other opportunities to intensify gas-solid fluidized bed operation

“…Designing a fluidized bed involves compromises between vigorous mixing and sufficient contact time, by optimizing bubble size and velocity [16]. While the bubble dynamics are scale-dependent and hard to predict [17], there are various ways to alter the overall hydrodynamics to improve particular processes [18,19]. These include altering the interparticle forces by adding flowconditioning particles [20,21], liquid binders [22,23], adsorption of gas and changes to the operating conditions [24,25].…”

Structured bubbling in layered gas‐fluidized beds subject to vibration: A CFD‐DEM study

“…Gas‐solids bubbling fluidized beds are widely used in many industrial processes, such as coal combustion, 1 biomass gasification, 2 pharmaceutical production, 3 polymer recycling, 4 and carbon capture 5 . The overall performance of gas‐solids bubbling fluidized beds largely depends on the bubble dynamics 6 . Rising gas bubbles in fluidized beds can promote particle mixing and therefore improve heat transport properties.…”

“…Very recently, Guo et al 20 found that vibrating gas fluidized beds at a resonant frequency can create similar bubbling structures as by pulsed gas flow, and the use of vibration can produce a more ordered structure, particularly as system size is increased. Since bubble motion is directly tied to overall gas and particle motion, 6 structuring bubbling effectively structures particle mixing and gas‐solids contact. Furthermore, when the system width is changed, the structured bubbling pattern as well as characteristic bubble size and bubble distance remain unchanged, 11,20 opening opportunities to address key issues in scaling up gas‐solids bubbling fluidized beds.…”

Comparison of Two-Fluid Model Simulations of Freely Bubbling Three-Dimensional Gas-Fluidized Beds with Magnetic Resonance Imaging Results

“…4 Despite several prior efforts, difficulties in characterizing bubbles experimentally and using modeling, as well as recent new developments for experiments 5−7 and modeling, 8,9 make it such that investigating bubbling fluidized beds is still an active area of study. 3 Computational modeling has become a powerful tool for characterizing fluidized beds in recent years due to (i) providing insights into the salient physics needed to capture fluidization dynamics, (ii) providing detailed insights into aspects that are difficult to measure, such as forces on particles 9 and gas flow, 10 and (iii) characterization of fluidized beds usually at lower cost than experiments. Because dynamics in fluidized beds occur on length scales from microns to meters and milliseconds to hours, multiscale modeling approaches are used to characterize these dynamics.…”

“…Gas–solid fluidized beds are used in a variety of industries, often in a flow regime in which gaseous voids, or bubbles, rise through suspended granular particles. Despite the similarity in shape and dynamics of bubbles in fluidized beds to those in conventional liquids, gaseous voids in fluidized beds do not form due to surface tension, and thus their dynamics have been of scientific interest for decades. , Similarly, since bubbles provide a main mechanism for particle conveyance and mixing in fluidized beds while also providing a mechanism for gas bypassing particles, characterization of bubble behavior has been of immense interest to engineers for decades . Despite several prior efforts, difficulties in characterizing bubbles experimentally and using modeling, as well as recent new developments for experiments − and modeling, , make it such that investigating bubbling fluidized beds is still an active area of study …”