Controlling density of slurry at paper machine head-box - using devices to regulate the amt. of fibre in suspension before being deposited on the wire

摘要

In a process to control the density of slurry at the headbox of a paper machine, the concn. of the suspension is altered by removing that part which is not average. Working on the principle that the feed pipes, sluices, or flat surfaces separate the slurry into layers of relative density and some clean water, according to the fibre length, a method is proposed to release only average suspension in the slurry. The higher, or lower density material is sepd. at the early stages, and re-introduced gradually, or at a different stage. The sepn. and re-use of different concentrations is initiated by sound waves in the head box. Subsequently the sepn. and re-direction may be attained by centrifugal action, for example by rotation or by turbulence. The higher concn. suspension will require an addn. of water to it, as the previously sepd. water was drained off. The concn. may, however, be raised to reduce the time of water extn. at later stages, in order to produce a better quality paper. ADVANTAGE - The suspension of fibres which is finally deposited on the wire results in the correct thickness of paper across the total width, which may be up to 10 metres.