Drag coefficient and volume fraction of bubbles in a supercritical water fluidized bed

The supercritical water fluidized bed (SCWFB) is a recently introduced reactor for biomass gasification that does not release pollutants. Four groups of Geldart B-type quartz sands with different particle sizes were fluidized at a system pressure of 20–27 MPa and system temperature of 410–570 °C. A series of experiments were performed for determining the drag coefficient and volume fraction of bubbles. The effects of the particles’ size, superficial velocity, system pressure, and temperature on the drag coefficient and volume fraction are discussed. In addition, a correlation between experimental and computed values is demonstrated for both the drag coefficient and volume fraction in SCWFBs. The relative error of the correlation is within ±30%. The results of this study provide significant guidance for the scaling-up design of SCWFBs and for the development of supercritical water gasification technology.