Influence of temperature on particle separation in granular bed filters

Abstract

The present study deals with the influence of temperature on the separation of fine dust particles in granular bed filters. Collection within the diffusion regime for particles smaller than 0.5 μm becomes more effective with increasing temperature. However, for larger particles subject to the influence of inertial forces, a drop in separation efficiency is to be expected due to increasing drag forces. With the aid of experimentally determined grade efficiencies at temperatures up to 800 °C, the influence of temperature and other important filtration parameters such as the filter medium's grain size or the filter face velocity, are quantitatively derived and discussed. Investigations concerning the long-term filter behavior have shown that the formation of a filter cake significantly improves separation efficiency. This not only depends upon the characteristics of the dust in question, but also is a function of the grain size of the filter medium and the filtration velocity. Under cake filtration conditions, high collection efficiencies may also be attained at temperatures up to 800 °C.