Introducing a thin permeation layer at the beginning of filtration, the governing differential equation for the filtration expressed in material coordinate derived in our previous papar (J. Soc. Powder Technol. Japan, Vol. 40, pp. 712-719) suggested that (i) the square of dry solid volume in a cake increases linearly with time, and (ii) there exists a similarity among the distributions of concentration, liquid pressure and liquid flow rate in the cake. In the present work, filtration experiments were carried out using four types of suspensions at low and high constant filtration pressures in order to examine the validity of (i) and (ii) as well as the consistency of the presented governing equation. As a result, the total solid volume and the wet to dry mass ratio of the cake were successfully predicted by the present model employing the average void ratio of the cake which was calculated theoretically, and (i) was found to hold for these suspensions. However, all of the filtration experiments showed that there was a time delay with a factor of 1.1 to 2.5 as those predicted by the present theory. The discrepancy may result from the viscous delay effect in thin cake layer near the filter medium, which was excluded in the present model. The effects of constitutive and permeation relation onto the distributions of concentration, liquid pressure and liquid flow rate in the cake were also presented.

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The average void ratio of cake is related to the compression resistance of the cake as well as the material balance during filtration. Filtration experiments with variable pressure showed that the dewatering effect is significant if the void ratio of the cake is larger than that of the feed suspension by a factor of, for example, four, and the effect is more pronounced with decreasing the permeation resistance. Furthermore, a simplified estimation method of filtrate volume for the variable pressure filtration is presented by employing the experiemental relationships between the pressure and the average void ratio and specific filtration resistance obtained in the constant pressure filtration and incorprating the mass conservation in the conventional filtration equation. The present method predicted the filtrate volumes of four types of suspensions with a relative error of 20 to 50%.

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Ceramic filters are commonly used to remove solid particles from high temperature gases. However it is still unknown whether or not hydrocarbons collected in ceramic filters are removed by pulse jet cleaning period. When a gas containing hydrocarbons is passed through ceramic filters, an increase in pressure drop is observed. We studied the collection and cleaning of hydrocarbons with boiling points of 470, 590 and 680K which were generated by the thermal decomposition of polystyrene. The mass of hydrocarbons collected on the unit surface area of ceramic filters (m_h) is related to the pressure drop (ΔP_f) with a correlation factor of 0.9, giving the regression equation, ΔP_f=50.7(m_h)²+887. The removal of hydrocarbons by pulse jet cleaning does not take place at 570K, but the they are completely removed by a heat treatment at above 720-780K for 7200s.

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