METHOD AND APPARATUS FOR DEWATERING A SUCTION PAPERMAKING ROLL

An air delivery device is provided for dewatering a suction roll in a paper machine by applying pressurized air to expel residual water or debris outwardly from through-holes. The air delivery device is positioned at a suitable circumferential position of the suction roll to prevent water carryover back to the suction box location. In one preferred embodiment, an internal blowbox is mounted near the inner surface of the suction roll for blowing out water from the suction roll holes to augment the natural centrifugal forces. The blowbox can be used as a standalone dewatering unit, or in conjunction with an external doctor blade or wipe. In another preferred embodiment, at least one air knife, air pipe or air shower is used for dewatering. In another preferred embodiment, at least one interior stationary air foil is used to generate a pressure pulse which creates outward air flow through the through-holes. In still another preferred embodiment, the blowbox may be provided with a self-loading structure for selectively loading it against the inner surface of the suction roll using variable air pressure control. All preferred embodiments can be used as standalone dewatering units, or in conjunction with an external doctor blade, external wipe or external air knife.