| abstract |
Removal of water from a fibre suspension, in particular cellulose pulp in a static thickner which essentially does not comprise moving parts. The clogging of the perforations in the screen sufaces (14,15,28,30,38,40,74,75,88,90) is reduced by dimensioning these perforations and the flow channels (13,33,37,76,87) in such a way that the pulp flows in the channels (13,33,37,76,87) as a plug flow, that is, the internal friction of the pulp is greater than the surface friction between the pulp and the screen surface (14,15,28,30,38,40,74,75,88,90). The process and apparatus (52,62) may be applied whenever a dilute pulp must be thickened, e.g. during pulp bleaching or refining of rejects. |