Onset of slugging fluidization in supercritical water fluidized bed

The supercritical-water fluidized bed (SCWFB) is a reactor for coal and biomass gasification without pollutant emission. We carried out a series of experiments in a SCWFB, and a dual-capacitance probe measurement system was applied to measure the hydrodynamics of slugs, such as the slug frequency, chord length, and rising velocity. Four groups of Geldart-B particles with different mean diameters were fluidized by supercritical water with a system pressure of 20–27 MPa and at 410–570 °C. The minimum slugging Reynolds number increases logarithmically with Archimedes number and a predicting correlation of the minimum slugging fluidization velocity in the SCWFB is presented: Re_ms=32908.84lnAr^0.55+260376.65−410361.90. The relative error of the above correlation was within ±15% and the averaged relative error was 7.5%. The effect of operating conditions on the minimum slugging fluidization velocity is discussed. This research provides useful guidance for scaling-up design and for determining the optimum range of operating conditions in the SCWFB.