| 摘要 |
1,222,394. Upward flow filtering beds. COMPAGNIE DES EAUX ET DE L'OZONE. 13 Feb., 1968 [16 Feb., 1967], No. 7122/68. Heading BID. Water is filtered by upward flow through a bed comprising layers of gravel and sand of upwardly decreasing particle size (exemplified), and the bed is periodically backwashed by a body of filtered water maintained above the bed and of approximately equal volume thereto. During filtration, the pressure drop across the bed is kept constant, and the volumetric flow rate declines as the bed clogs. To maintain a constant overall flow rate, several beds in different stages of clogging may operate in parallel. The prior art refers to upward flow filtration wherein the pressure is increased to maintain constant flow rate until the retained solids are suddenly released from the bed into the filtrate stream. |
