A four-quadrant flow regime map for two-phase liquid-solids and gas-solids fluidization systems

Previous flow regime mapping work in both gas-solids (GS) and liquid-solids (LS) fluidization systems were carefully reviewed. A set of complete four-quadrant flow regime maps that unifies all the operating modes in both the GS and LS fluidization systems was proposed. The flow directions of the fluid and particle velocities were used as the abscissa and ordinate of the proposed four-quadrant regime map. All the fluidization systems then can be divided into four groups: cocurrent upward (Quadrant I) and downward (Quadrant III), counter-current fluid-down and solids-up (Quadrant II) and fluid-up and solids-down (Quadrant IV) in the regime map. The relative density between the particle and fluid was also selected as a parameter to differentiate operations of GS downer and LS inverse fluidized bed in Quadrant III. The transitions to and the limits of the flow regimes were discussed in detail. Some new flow regimes such as the GS circulating turbulent fluidization and the LS conventional circulating fluidization regimes were also outlined in the proposed regime map.