GRAVEL BED DUST COLLECTOR

1501705 Filter apparatus for hot gas REXNORD INC 11 April 1975 [23 April 1974] 14926/75 Heading BIT Downward - flow filter beds of sand or other granular material in respective housings 3 are stacked vertically around common inlet and outlet ducts for raw and filtered gas and reverse flow gas supply and receiver ducts, respective valves connecting the upper and lower sides of each housing in parallel to all four ducts so that beds may be reverse flow cleaned individually or in pairs while other beds remain on forward flow. Reverse flow cleaning is accompanied by raking the beds (Fig. 2 not shown). The inlet duct 32 has a lower outlet valve (34) to discharge solids settling therein, and the reverse flow gas receiver duct or ducts 37 deliver the gas to cyclones 40, which return the gas to the inlet duct and discharge the solids to conveyor 35. The reverse flow supply duct 46 may be sandwiched between inlet and outlet ducts to warm reverse flow gas and avoid condensation. Filter bed housings could be helically spaced instead of being vertically stacked.