Quantitative criteria for emulsion phase characterization and for the transition between particulate and bubbling fluidization

Formation and Measurement of the Porosities, Tensile Strengths, and Deformation Coefficients of Gasification Filter Cakes at Operating Temperatures and Pressures

“…l a Then, if the assumption that Nf has the same value for some other set of conditions is valid, af can be determined by the measurement of 4P7 under the latter set of conditions. Experiments by Kono and coworkers (Kono et al, 1987(Kono et al, , 1994(Kono et al, , 1995(Kono et al, , 1997Smith et al, 1996) with a variety of powders have shown that, indeed, this assumption often is an accurate one for many different conditions.…”

“…1. Intuitively, the number of layers in the powder along the direction of gas flow may be thought of (Kono et al, 1987(Kono et al, , 1994(Kono et al, , 1995(Kono et al, , 1997Smith et al, 1996) as the cake thickness divided by an effective particle diameter, d " :…”

“…Although increasing the gas flow through the powders of this and other (Kono et al, 1987(Kono et al, , 1994(Kono et al, , 1995(Kono et al, , 1997Smith et al, 1996) studies compresses the powder to a smaller thickness, reducing the flow rate (but in the same direction) does not cause the compressed powder to "rebound." As shown by Kono (Kono et al, 1987, 1994, 1995Smith et al, 1996), the coefficient for the deformation of the powder can be determined from measurements of the compressed-powder pressure drop and the loose-packed and compressed-powder thicknesses: Figure 2a is a plot, versus the filter cake porosity (t.), of the compressive pressure gradient on the cake (M,*/HC) caused by the gas flow through it during its formation.…”

“…During the past several years Kono and coworkers (Kono et al, 1987(Kono et al, , 1994(Kono et al, , 1995(Kono et al, , 1997Smith et al, 1996) have developed experimental methods and interpretational models that make it possible to form cake deposits under many of the conditions that obtain in large-scale hot-gas filtration vessels and to measure their porosities, permeabilities, tensile strengths, and deformation coefficients under these same operating conditions. In IGCC and PFBC filtration vessels with candle filters, hot gases and elutriatcd particles enter the filter vessel, the hot gases pass through the walls of the filters, filtered particles gradually build up cakes on the filters' outside walls, and these cakes then are removed (1998) by reversal of the direction of gas flow.…”

“…In IGCC and PFBC filtration vessels with candle filters, hot gases and elutriatcd particles enter the filter vessel, the hot gases pass through the walls of the filters, filtered particles gradually build up cakes on the filters' outside walls, and these cakes then are removed (1998) by reversal of the direction of gas flow. Phenomenologically, the method of Kono (Kono et al, 1987(Kono et al, , 1994(Kono et al, , 1995(Kono et al, , 1997Smith et al, 1996) closely mimics many of the mechanisms by which cakes form on filter surfaces and then are removed by reversal of the gas-flow direction. Moreover, this technique can form filter cakes and measure their porosities, permeabilities, tensile strengths, and deformation coefficients in a single laboratory apparatus and under conditions of gas flow rate, composition, temperature, and pressure that mimic those of large-scale industrial plants.…”