We often use a rotary kiln with a ring weir. But there have been few studies on how the ring weir affects the hold-up ratio and the time τ required for the material to pass through it.
In this paper, the author assumes that the advancing movement of the material is due to the rotation of the kiln, and on this hypothesis the velocity of the moving material in any section is represented by the equation:-
The inltuence of the height of the ring weir on the hold-up ratio in any section and that on the time required for the material to go through the kiln are also discussed.

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F.M. Tiller¹⁾, using a consolidometer, got the functional relation of the cake porosity (ε) to the pressure on cake-solid (P_s), and, applying this functional relation to the case of filter cakes, obtained indirectly the liquid pressure distribution curves.
We, however, measured directly the liquid pressure distribution during actual constant pressure filtration, to investigate how the distribution varied with the filtrate volume (V), the concentration of the slurry (s) and the filtration pressure (P_o). We used chiefly the slurries for ignition plugs, and a kieselguhr slurry as well. The liquid pressure was measured with the air-sealed glass capillary manometers as shown in Fig. 1.
As the result, we got Figs. 7 & 13, from which we obtained
(1)
and
ν_??_0.48, for the ignition plug slurries within the range of P_o=5.05-0.965kg/cm²
ν_??_0.83, for the kieselguhr slurry.
The value ν might be taken as a measure of the so-called incompressibility of the cake, and it seemed that ν was nearly independent of any of V, s and P_o within the range of our filtration pressure experiments.
The thickness of the cake (L) increased linearly with the filtrate volume (V), which proved the m-value to be coincident with the m-value obtained by the method described in our former report²⁾.

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Tiller¹⁾ calculated the p_x-distribution curve within filter-cakes in constant pressure filtration, assuming that the flow of water through filter-cakes was equal to that through the compressed bed in permeability tests. He also assumed that (k·S₀²) of the filter-cakes was constant. But, according to Grace³⁾, Michaels, etc.⁴⁾, (k·S₀²) varied with porosity, ε, remarkably.
So we made compression-permeability experiments, using the ignition-plug slurries, and applied the experimental data to plotting the p_x-distribution curve, without assuming (k·S₀²) to be constant.
We compared the newly derived p_x-distribution curve with the one obtained from direct measurements of p_x within cakes. We also calculated average porosity of filtercakes, ε_av, from the experimental data, and compared it with the average cake porosity, X, in constant pressure filtration.
As shown in Table 7 and Fig. 10, ε_av & X were always coincident, but two kinds of p_x-distribution curves mentioned above did not coincide, as shown in Fig. 11 & 12.

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