| 摘要 |
<p>Water or other liquid to which a coagulation reagent has been added is introduced into a decantation zone at a rate of flow which is sinusoidally modulated; sediment is formed in the zone, and a portion of it is removed and re-injected into the zone at a rate of flow which is also sinusoidally modulated, but not in the same phase as the water flow. Preferably the phase difference is p /2. The cycle of operations thereby produced consists of four stages: a working stage, during which a sludge bed (for upward flow of liquid therethrough) is formed; an expansion stage, during which some treated liquid and some sludge are removed separately from the apparatus; a further working stage, during which further sludge is formed by agglomeration of particles; and a compression stage, during which heavy particles from the sludge bed descend into, and are segregated in, concentrators which constitute quiescent zones; (it is from these concentrators that sludge is removed during the expansion stage). To enable smooth operation to be established, the flow-controlling devices are duplicated, one set of devices working in opposite phase to the other. Operation and control The liquid and sludge are moved in "feed" devices by compressed air provided by a continuously-operating compressor, and the sinusoidal effect is produced by permitting some of this air to leak to the atmosphere through escape valves which are progressively opened and closed. The opening and closing are performed by rotary mechanism whose direction of rotation is periodically and automatically reversed. Connection of the feed devices to either the compressed air supply or the escape valves is governed by remote-controlled valves operated electrically in sequence by a cam-and-contact unit driven by the above-mentioned rotary mechanism. A control desk is provided. The time-period of a complete sinusoidal variation, the flow amplitude (i.e., difference between maximum and minimum flow rate) and the phase difference between liquid flow and sludge flow, may all be varied.</p> |
