(286d) Generalized Flow Regimes for Fluidization and Fluid-Solid Vertical Transport

Flow patterns and flow regimes in gas-solids two-phase fluidization and vertical flow systems have attracted a great attention in the multiphase research community since 1940s. Wilhelm and Kwauk (1948) pioneered the bed expansion behaviour of fluidized beds and developed criteria for two types of fluidized bed flow patterns: particulate and aggregate fluidization. Kwauk further developed a generalized fluidization flow regime map in 1960s. Since 1970s, a number of flow regime maps have been proposed to distinguish different unique flow patterns. Although it has been commonly agreed that there exist distinct flow patterns in gas-solids fluidized beds and vertical transport lines, such as the bubbling and slugging fluidization and dilute phase transport based on extensive research from 1940s to 1960s. Controversies still exists on the existence of turbulent fluidization, which was first proposed in late 1960s, fast fluidization, which was first proposed in late 1970s. The transitions from low velocity fluidization to fast fluidization, dense suspension upflow and, most recently, turbulent flow, are still not well defined. Further work on this topic is warranted in order to develop a generalized flow regime diagram for the flow pattern identification. In this presentation, we try to examine the flow patterns in generalized gas-solids vertical fluidization and transport systems in hope that such an analysis will shade some light on the understanding of flow regimes and regime transitions.