A Review of Mixing and Segregation in Fluidized Beds
Ben Freireich, PhD
Particulate Solid Research, Inc. (PSRI)
Solids mixing in a fluidized bed is efficient. The act of fluid passing through a bed of suspended solids as bubbles or other macro-voids. All of which tends to transport and mix the solids well. Combined with the inherent high heat capacity of most solids, this mixing translates to the very high rates of heat transfer; a key feature of fluidized bed applications. Therefore, mixing and segregation challenges in fluidized beds are typically not of significant concern. However, shifting commodity prices, environmental trends, and other technological advances have led to the development of several fluidized bed technologies that incorporate mixtures of two or more fluidized solids (e.g. catalyst, reactant, heat transfer media, fuel, or any combination thereof). Due to their functional requirements or raw material source, these components may have markedly different sizes, shapes, densities, etc. In fact, several technologies require simultaneous fluidization of components spanning several Geldart groups; which individually have very different fluidization behavior.
In this presentation a review of existing knowledge as it pertains to fluidization of mixtures will be presented. The review will provide a summary of existing knowledge as well as gaps available for future investigation.
Ben Freireich is the Technical Director at Particulate Solid Research, Inc. (PSRI) and previously a Research Scientist in Engineering Sciences at The Dow Chemical Company in the Solids Processing Lab. He obtained his PhD in Mechanical Engineering from Purdue University studying manufacturing processes involving solid materials (particles, powders, etc).
At PSRI, Ben guides member and contract research efforts executed by the technical staff. PSRI is a consortium-based research company with member companies across the globe that applies and generates fundamental research in the area particle technology with focus on fluidized systems. At Dow he was involved in many products and processes, with expertise on powder flowability, fluidization, size enlargement, attrition, and other areas of solids processing.
Ben has over 20 publications and over 350 citations, sits on the Executive Committee of the AIChE Particle Technology Forum, is the Chair of ASTM D18.24 sub-committee on Characterization of Bulk Solids and Powders, and was recently named one of AIChE’s 35 under 35 for 2017. He lives in Chicago, IL and has four children.