| 摘要 |
A sand filter is provided where dirtied filter media, generally sand, is continuously withdrawn from the filter container and lifted to the top of a juxtaposed separate wash vessel outside the container. The dirty media cascades in zig-zag fashion across and down a series of vertically spaced inclined baffles in the wash vessel extending alternately from opposite sides of the vessel so that a thin, relatively wide media stream falls from one baffle down to the next. A wash liquid, normally clean filtrate from the sand filter container, enters an inlet port adjacent to the bottom of the wash vessel and due to the coaction of the spaced baffles forms vertically-oriented circular flow patterns or vortices in alternative clockwise and counter clockwise directions so that portions of the wash liquid flow are directed to flow along with and in the same direction i.e. co-current flow, as the downwardly progressing and cascading media stream falling from one baffle member to the next baffle member. During this co-current flow, dirt particles are displaced from the dirty media. The cleaned media is returned from the bottom of the wash vessel to the filter container for reuse and dirtied wash water is removed from the top of the wash vessel. |
