| 摘要 |
A filter element 18 for use in a precoat filtering device, e.g. a condensate polisher, comprises a perforated tubular core 82 e.g. of stainless steel having an open area of 20%, covered with at least two layers 84, 86 of filter material, preferably wound strand layers. The outermost layer 86 can retain finer particles than the innermost layer 84. The innermost layer 84 serves to increase the filtering area of the outermost layer and evenly distributes backwash water. A third layer of intermediate particle retention ability may separate the layers 84 and 86. In a condensate polishing plant a plurality of elements 18 are precoated with an ion exchange resin and used to remove dissolved and undissolved impurities from boiler feed water. <IMAGE> |
