| 摘要 |
624,924. Filtering apparatus. SERVICES INDUSTRIELS DE GENEVA. Nov. 11, 1946, No. 33480. Convention date, June 17. [Class 46] [Also in Group X] The apparatus comprises a tank in which is placed a slab of porous substance of which the upper face is flat and smooth and on which the granular filter mass lies, while its lower face comprises separate cells, the slab being supported by a watertight floor forming a closure for the cells and being traversed by waste-flow tubes opening into the cells and by tubes opening into cavities in the, lower surface of the slab, which latter tubes serve for escape of gas during cleaning of the apparatus. In a tank 1 is disposed a slab 2 of porous concrete made up of contiguous units 4, each of which defines a cell 5 on its undersurface, each cell having a regular series of circular depressions 6. The slab 2 is supported on a watertight false bottom also made up of units 8, which is, in turn, supported on ledges 11. Hollow pipes 14 extend from the upper surface of the false bottom into the lower part of a collector chamber 18, and pipes 12, packed with porous concrete 13, lead from the depressions 6 into the upper part of the chamber 18. A layer of loose material 15 is supported by the slab 2. Means for ensuring watertightness are provided between the edges 7 of the units 4 and the false bottom, and between the upper parts of the adjacent faces of the units 8; also between the outermost units 8 and the wall . 1 and ledge 11. Liquid to be filtered is distributed evenly over the sand 15 and percolates through the porous slab 2 and pipes 12 and 14, reaching the chamber 18 mostly by the pipes 14. For cleaning the bed 15, the outlet 17 is closed and unfiltered liquid is withdrawn from the bed 15. Compressed air is then supplied to the chamber 18, and rises first through the porous concrete 13 in the pipes 12 and then through the slab 2 to agitate the bed 15. Then filtrate is supplied under pressure to the chamber 18 and passes up the pipes 14 into the cells 5, through the slab 2 and into the mass 15, the air continuing to pass up the pipes 12. When the required level is reached in the region above the mass 15, the intake of air is stopped, and after a short period during which the mass 15 settles, the pipes 16 are opened and the backwash liquid siphoned off, the siphoning operation drawing more liquid through the bed. The operation is stopped when the cleansing liquid is limpid. The filter mass 15 may consist of any granular substance hard enough to resist wear due to regeneration. The particle diameter may be in the range 0.5mm. to 1.2mm., but the variation from the chosen diameter should not exceed Π15 per cent. |
