| 摘要 |
<p>1463119 Pulping waste paper BELOIT CORP 12 March 1974 [22 March 1973] 10958/74 Heading D2A To recover substantially dry pulp from waste paper an amount of aqueous moisture and a liquid immiscible with water are added to the waste paper, the mixture is defibred at elevated temperature and pressure, then the aqueous moisture is removed from the fibres to a predetermined dryness by reducing the pressure to atmospheric and the immiscible liquid is removed substantially completely from the fibres. The immiscible liquid, preferably tetra- or tri-chlorethylene, protects the fibres and prevents dumping while the moisture breaks the bonds between fibres. As shown waste paper is supplied to a chamber 12 where it is subjected to a countercurrent of superheated steam 14 and a spray 15 before being passed through a rotary valve 16 into a pressurised mechanical defibrer 19 where preheated immiscible liquid is added on line 46 to bring the mixture to about 96% liquid, 2% water and 2% pulp. The mixture then passes to a separator 21 having a rotating tubular screen 22 divided internally by a stationary wall 27. Fibres pass around the outside of screen 22 to an outlet 31 while the immiscible liquid, carrying any contaminants, flows out through outlet 23 to be recycled and replaced by preheated fresh immiscible liquid on inlet 26. The mixture on line 31 is fed to a second pressurised defibrer 32 and thence to a demoisturing tank 35 at atmospheric pressure. Most of the water and some of the immiscible liquid evaporate off in the tank 35 to be recycled by system 35b. The remaining mixture is fed to a mechanical press 38 where the immiscible liquid is removed to be subsequently filtered at 44, heated at 45 and fed back to defibrer 19. Fibres from the press 38 are passed to a chamber 39 where they are subjected to a countercurrent of superheated steam to evaporate the remaining immiscible liquid substantially completely, and to control the dryness of the fibres.</p> |
