| 摘要 |
The invention provides a discharge roller for a vacuum belt filter, over which a filter cloth of the filter passes, the roller having a channelling means in the form of a plurality of longitudinally directed and circumferentially spaced-apart passages which are each in communication with a different segment of the cylindrical surface of the roller via suitable radially directed bores and an end valve for directing a discharge fluid to those passages which are in communication, at any particular time, with that portion of the cylindrical surface engaged by the filter cloth, such that there is flow of the discharge fluid in a reverse direction through the cloth to separate residue cake therefrom. In order to ensure contact between the filter cloth and the roller the roller may be driven or the cloth may be sucked against the roller, further passages and bores being provided which are selectively connected to a suction source by a further end valve, the passages being in communication with different segments of the cylindrical surface of the roller via the bores. A number of longitudinally directed, circumferentially spaced-apart channels may be provided in the cylindrical surface of the roller, for distributing the discharge fluid and the suction force. |
