| 摘要 |
Drop-back of solids into the drum pool of a rotary microscreen is reduced by applying a limited gas pressure differential across an unsubmerged portion of the screen cloth. The pressure is not for the purpose of increasing the driving force, DELTA H, of the liquid passing through the cloth. For purposes of this disclosure, DELTA H is the pressure differential existing across the screen below the surface of both the drum pool and tank pool. In fact, assuming other factors remain equal, application of a gas pressure differential to an unsubmerged portion of the screen cloth, with consequent reduction in drum pool suspended solids concentration, will normally reduce DELTA H even though the gas pressure also acts on the surface of the drum pool. More significantly, the invention enables operation of a microscreen unit at increased flow capacity at a given DELTA H. Whatever pressure is applied, there will be some reduction of torque, bearing load and wear at any given DELTA H.
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