| 摘要 |
An appts. for the countercurrent washing of a granular filter bed consists of a pipe at the end of which is a ball valve, in the space above the bed, within the filter chamber. Above the filter chamber is a chamber where filtrate accumulates, open at the top and operating at a constant level during normal filtration by gravity. This filtrate chamber is fed by a pipe connected to the space below the filter bed. Water to be filtered enters froma fed tank through a pipe entering the copper part of the filter chamber. Filtrate leaves through a rising pipe connecting the space below the filter bed to the discharge. As the bed becomes choked with sediment, the static pressure in the filter chamber increases. The ball valve is forced away from its seating and the pressure in the filter chamber falls, allowing water to flow from the filtrate chamber to the space below the filter bed and into the upper part of the filter chamber, passing upwards through the bed and cleaning it. the pressure redn. may be brought about by a float valve. The apps. is simpler and costs less than existing appts. The ball can be replaced by another one with different lifting force from different granular filter beds. |
