Granular gas filter - with narrow annular beds stacked cleaned by double reverse impulses

摘要

Narrow annular filter beds, e.g. of No. 1/2 sand, are stacked vertically, with pref. slit perforated screen peripheral inlets at tops, and similar screen outlets at bottoms; to clean e.g. inert gases from steel or chemical processes, which are introduced to a chamber surrounding several such stacks, and after passing through beds exit from a chamber below a conical partition supporting stack bases. Beds are cleaned by double reversed jet impulses introduced axially to stacks, to produced a flow rate twice that required for fluidization; use of narrow beds overcomes problems of uneven bed depth, due to angle of repose of granular powder falling back to form bed after cleaning stage. To deal with particles, e.g. of TiO2, likely to clog bed, tops of beds may be sloped inwards at about 30 degrees to peripheral wall of stack.