| 摘要 |
<p>Gas diffusion elements, formed of a body of solid particles which have been shaped, pressed and rendered coherent by bonding or nintering in a compacted form having pores, are disclosed. Said elements include a peripheral, annular zone of relatively small proportions having lesser permeability, greater density or lesser height lesser permeability, greater density or lesser element. In accordacne with the invention, a boundary zone is provided adjacent to and inwardly of the peripheral zone, in which boundary zone there is a progresive increase, continous ration of the element, in the direction metric compression ratio of the element, in the direction of the peripheral zone, or towards a vertical surface which is near the periphery of the element. Such element may provide improved gas, e.g. oxygen transfer efficiency and therefore holds promise of improving the efficiency and economics of gas transfer processes, such as for instance treatment of sewage or other waste water with air, oxygen and/or ozone.</p> |
