Mechanistic Modeling of Granular Bed Filters for the Removal of Particulate Matter from High-Temperature, High-Pressure Gas Streams: A Critical Assessment

摘要

In several coal conversion processes involving the generation of electrical power from coal, it is necessary to remove the particulate matter from flue gases at high temperatures and pressures. Several variants of granular bed filters involving fixed beds, moving beds, intermittently moving beds, and fluidized beds are being examined to accomplish this goal. This report deals with the review and critical assessment of the mathematical models which have been developed to date to describe the filtration efficiency and pressure drop across such filters. It is hoped that a reliable model will fulfill the basic needs of engineering design and scale-up. Further, the areas in which the future research and development work should be directed are identified in the light of available literature. The particulate removal from a dust-laden gas stream in a granular bed filter takes place by a combination of several collection mechanisms. These are: gravitational settling, interception, impaction, Brownian diffusion, and external field effect. The mechanistic details and the corresponding controlling parameters for all these processes are identified and outlined. Various semitheoretical expressions and models developed for collection efficiency for clean bed filtration and for deposition on the filter cake formed by the collection of dust particles are reviewed and discussed. Similar efforts dealing with the filter pressure drop are also described. (ERA citation 06:002301)