Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Patent
1997-04-14
1999-02-09
Hastings, Karen M
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
100118, 100120, 210401, 162323, 1623581, B01D 3352
Patent
active
058689036
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for dewatering and/or washing suspensions, especially fibre stock suspensions, with two dewatering rolls rotating in opposite directions, where at least a further two guide rolls, especially press rolls, are provided and an endless woven wire or filter belt runs over each combination of one dewatering roll and one further guide roll, by which arrangement the suspension to be dewatered and/or washed is carried in the gap between the two belts and dewatered.
The devices already known have, in some cases, only two dewatering rolls rotating in opposite directions or are so-called twin wire dewatering units in which additional guide rolls and suitable wire or filter belts for dewatering are provided in addition to the dewatering rolls. Furthermore, the converging wire or filter belts run horizontally in most of these devices. Such devices can be used advantageously for dewatering, especially dewatering of fibre stock suspensions, blat have no facility for washing the suspension. If the suspension sometimes has to be washed and at other times is required without being washed for different application, large scale adjustments or modifications have to be made when using the devices already known.
EP-A-0 454 989 describes a vertical former with various form elements, where the suspension is injected into the gap between the belts. The first dewatering takes place in the roll gap or slot.
EP A-0 311 834 describes a dewatering device where sludge, fruits and vegetables or waste of pressed fruits or vegetables are dewatered by dewatering cogwheels. Here the material to be dewatered is fed through a chute arranged above the cogwheels, and falls onto the cogwheels and the belts. The belts are driven around the respective cogwheel, a deflecting roll and a (belt) dewatering roll. Important for this document is that the belts are driven together only on a short distance to reduce the wear.
U.S. Pat. No. 3,915,865 describes a dewatering device where the sludge is first led along a horizontal path while being dewatered by gravity. Then the belts are deflected by press rolls and guided together to a vertical gap from top to bottom.
SUMMARY OF THE INVENTION
The aim of the invention is to create a universally applicable device for dewatering and also for washing suspensions if necessary.
The invention is thus characterised by the two belts forming a vertical gap or slot and by a device to guide the web being mounted in the region of this vertical gap, which device can take the form of a guide roll or a guide or sliding plate. Arranging the gap vertically on the one hand avoids any re-wetting of the material that has already been dried and on the other hand, a high throughput can be achieved on a very small floor area. By including a device to guide the web, formed by the dewatered material in the vertical slot, such as a guide roll or a guide or sliding plate, for example, the belts in the region of the vertical gap are maintained under suitable pressure, thus guaranteeing the required dewatering effect.
A favourable further development of the invention is characterised by curved guiding plates or jackets being mounted over the width of both dewatering rolls to form an adjustable, narrowing gap between the guiding plates or jackets and the wire or filter belts, especially endless woven wire or filter belts, which run over the surface of the dewatering rolls and then over the further guide rolls. These curved guiding plates are mounted on swivel bearings and can be divided, if necessary, into at least two sections, each with an adjustable inlet gap between the guiding plate and the roll surface. The inclusion of guiding plates allows the pressure on the suspension to be increased continuously in a particularly favourable way and thus permits sufficient dewatering. If the guiding plates are mounted on swivel bearings, this pressure can he varied and adjusted accordingly. The division of the guiding plates into several sections allows washing liquid to be fed in at
REFERENCES:
patent: 3832282 (1974-08-01), Parker
patent: 3839143 (1974-10-01), Suckow
patent: 3915865 (1975-10-01), Hajietal
patent: 3980518 (1976-09-01), Ljung et al.
patent: 4543161 (1985-09-01), Fujimoto
Mausser Wilhelm
Petschauer Franz
Sbaschnigg Johann
Andritz-Patentverwaltungs-Gesellschaft m.b.H.
Hastings Karen M
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