US Patent 7811454 Displacement filter apparatus

A method and apparatus for filtering a slurry utilizing a displacement filtering principle. The filter apparatus desirably includes an inner filter and an outer filter. Both the inner and outer filters are preferably substantially annular in shape and positioned concentrically with respect to each other. A particulate collection volume is at least partially defined between the inner and outer filter. The method includes directing a flow of slurry into the particulate collection volume under sufficient pressure to force fluid within the particulate collection volume through one of the inner and outer filters and any particulate matter blocking a filtering surface of the inner and outer filters.