GB1338518A - Method and apparatus for making a continuous web of fibrous particles - Google Patents

Abstract

1338518 Paper-making A AHLSTROM OSAKEYHTIO 15 June 1971 [15 June 1970] 28076/71 Heading D2A A paper web is produced by forcing a liquid suspension of fibres of high concentration, viz 1% to 6%, through a succession of constrictions and deflecting the suspension after each constriction to create a turbulent flow, the constrictions being interconnected such that the flow is directed through successively smaller constrictions with the flow from all but the smallest constrictions being directed to a plurality of smaller subsequent constrictions, the smallest constrictions having a size small enough to prevent an imaginary spherical body whose diameter is more than three times the mean fibre length from passing through the constrictions, whereby the eddy size and vorticity in the suspension respectively decreases and increases, and subsequently allowing the turbulence to decay so that a continuous matrix of fibres is formed which is deposited as a web. The suspension is fed to a distribution chamber 19 having outlets 15 opening into circular cavities 16 each provided with outlets 18 which lead to a common divided chamber 13 leading to an outlet channel 12 having an outlet slice 23. The smallest dimension of the channel 12 does not exceed twice the mean fibre length. In another embodiment, Figs. 1 to 5 (not shown), the suspension is fed to a unit comprising a pipe having a constriction at one end leading to a cavity having a wall facing the constriction and having radially extending outlets which lead in cascade manner to similar successively disposed units. An inlet for fresh water for use when starting may be disposed in the wall facing the constriction in each unit. The outlet channel has diverging walls to allow expansion of the matrix which may be deposited on a wire, direct onto a press felt, between two felts or directly to a press. The fibres are 1 to 5 mm. long and 30 to 50 Á.m. wide.