Headbox for distributing pulp suspension and additives

摘要

A headbox for a paper machine which mixes suspension and additives to achieve a selected basis weight cross direction profile and fiber orientation cross direction profile in paper produced from the machine. The headbox has sections across its width. Each section is supplied with a first stream QH of one suspension component, a second stream QL of a second suspension component. A valve regulates the total suspension flow QM as well as the ratio between the first and second streams. An additive stream Qad for each section communicates into the combined suspension flow. A valve regulates the additive stream for achieving the selected profiles. Various places along the suspension flow path are indicated as inlets for the additive stream. The headbox has a microturbulence generator for generating turbulence in the suspension passing through it. There may be lamellae within the headbox which somewhat separate the entry flow into the headbox. That version of the headbox has separated entrance flows with different additives at different layers. The invention further concerns a method of use of the headbox which results from the structure described above. <IMAGE>