Machine for washing fibrous suspensions

Abstract

A machine (1, 100) for washing fibrous suspensions (S), composed by cellulose fibres and pollutant agents, comprising: a frame (2); a pair of cylindrical drums (3, 4); a flexible belt (5) provided with through holes (6); conveying means (7) able to carry the fibrous suspension (S) at the zone (8) of incipient contact between the flexible belt (5) and the first drum (3); driving means (9) able to put in rotation at least one of the drums (3); collecting means (10) of the liquid and pollutant agents and collecting means (11) of the cellulose fibres. The conveying means (7) comprise: a head box (12) disposed below the flexible belt (5) and upstream the first drum (3), said head box (12) comprising a conveying conduit (13) of the fibrous suspension (S) provided with an outlet mouth (14) transversally disposed with respect to the flexible belt (5); a flow conveyor (15), disposed between the head box (12) and the first drum (3), comprising a laminar body (16) provided with an inlet edge (16a), disposed downstream the outlet mouth (14), and with an outlet edge (16b), disposed immediately upstream the contact line of the flexible belt (5) with the first drum (3).

Description

technical field [0001] The present invention relates to a machine for washing cellulose fibers used in papermaking. Background technique [0002] It is known that in the papermaking process different cellulosic fiber raw materials are used and their characteristics must be carefully selected, since these characteristics are decisive factors in determining the quality of the paper produced. [0003] In particular, the cellulose fibers must be separated from the pollutant particles present in it, this separation being particularly important when the feed material is such as waste paper or the like. [0004] This separation is accomplished by means of special machines for washing the fibrous suspension, however, in various embodiments, all machines essentially consist of a pair of drums, at least one of which is a driven drum, A flexible drive belt provided with through holes is wound over the drum in the form of an endless loop. [0005] The pair of drums includes a grooved ...

AI Technical Summary

Problems solved by technology

[0017] It is obvious that said fiber loss involves a loss of raw material with the consequence of increased costs

[0018] Another recognized drawback is due to the fact that due to the turbulent movement of the fiber suspension between the flexible belt and the drum, the shortest cellulose fibers tend to pass through the holes of the belt, even in the immediate vicinity of the belt and the drum. The same is true for the area downstream of the line of contact between cylinders, which further contributes to the loss of material

[0019] Another drawback is due to the fact that on machines of known type it is not possible to vary the velocity and thickness characteristics of the fluid exiting the headbox without changing the pressure above the headbox and thus the throughput

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