Papermaking assembly fibre suspension headbox has throttle control of dilution mechanism in outer margin

摘要

A papermaking assembly has a headbox that receives a supply of fibrous suspension and water that is introduced via an inlet to a line of mixer chambers (28) in which the consistency of the ingredients is individually regulated. The mixer chambers (12) discharge to a dilution chamber (16), followed by vortex generator channels (20) and a jet outlet (22). The volumetric suspension flow is individually regulated as required by a throttle (36) in the dilution chamber outer margin (38). The flow in the outer margin (38) is separate from the remainder of the dilution chamber. The throttle varies the local pressure loss in the range of 300 to 2,000 mbar. Flow control in the outer margin harmonizes the fibre orientation in the outer paper margin with that of the centre section.