| 摘要 |
Backflushing with internally mounted pistons (146, 46) and cylinders (42, 142) is provided in a pulp treating vertical vessel (11) such as a paper pulp thickener, diffuser, or displacement bleacher. First and second sets of screens (23, 25) are mounted on a supporting arm/conduit (16-20) within the vertical vessel, the first screens (23) mounted directly to the arms and the second screens (25) mounted on top of the first screens. A first cylinder (42) is connected at one open end (43) to the conduit and at the other open end (44) is exposed to the pulp within the vessel. A second cylinder (142) is mounted so that it is concentric with the first cylinder and both ends are in operative communication with the liquid conduit. A piston is mounted within each cylinder by a common vertically extending piston rod (47) which connects them. The pistons and cylinders have different effective diameters. Relative movement between the pistons and cylinders is effected periodically in order to force liquid from within the cylinders into the conduit and ultimately out the screens to provide backflushing of the screens, which prevents clogging.
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