| 摘要 |
PURPOSE: To eliminate choking of a filter, and obtain a high purity machining liquid by composing a device in such a way that amount of a concentrated liquid supplied to a pipeline per unit time is larger than penetrant eliminated from the filter. CONSTITUTION: A concentrated liquid is supplied by a second pump 16 from a middle container 6 to a thin film filter 17 to be circulated through a return pipeline 8 to the middle container 6. This thin film filter 17 has a cylindrical thin film 22, a concentration zone 23 is isolated from a penetration zone 24 by the thin film 22, it is enclosed by a cylindrical wall 25, and a penetrant is supplied from the thin film filter 17 through a feed pipe 20 to a tank 7. The thin film filter 17 is connected to a pipe 27 to supply mixture of water and air through a motor-operated valve 26 for return washing. A flow amount of the concentrated liquid flowing into the concentration zone 23 is set larger than amount of penetrant eliminated from the filter 17. Choking of the filter 17 is thus eliminated, and high purity machining liquid can be obtained. |
