A CONCENTRATOR PRESS

Abstract: A concentrator press includes a pair of rotatble press rolls (1) which coact with one another. The press rolls have apertured or perforated mantle surfaces (5) for removing liquid from a liquid-drenched material (3) to be concentrated and advanced between the press rolls. A part of the peripheral surface (5) of each press roll (1), including at least those regions in which the press roll acts on material undergoing concentration, is surrounded by a respective endless filter-cloth web (6, 7) which also runs around at least one direction changing roller (10; 10, 17, 18) at a distance from its associated press roll (1) and the still not concentrated, liquid-drenched material (3). The filter-cloth webs (6, 7) extend generally parallel with each other downstream of the press nip, to a concentrated material delivery station (15, 16).

Description: A CONCENTRATOR PRESS The present invention relates to a concentrator press of the kind which comprises a pair rotatably drivable press rolls which are arranged for mutual coaction and which have apertured or perforated mantle surfaces for removing liquid from a liq¬ uid-saturated material to be concentrated and advanced between the press rolls, wherein each of the press rolls is embraced around a part of its periphery, including at least the region in which the roll acts on the material undergoing concentra¬ tion, by an endless filter-cloth web which also runs around at least one web direction changing roller located at a distance from its associated press roll and the not yet concentrated liquid-drenched material. Concentrator presses of the aforesaid kind are known from SU-A- 561 765 and are used to increase the dry solid contents of liq- uid-particle or liquid-fibre suspensions or liquid-rich parti¬ cle pulps or fibre pulps, such as for de-watering cellulose pulps, for instance. A large total hole area in the apertured or perforated mantle surfaces of the press rolls is therefore desirable from the aspect of capacity. The size of the perfora¬ tions in the mantle surfaces of the rolls can be increased, with subsequent improvement in the permeability of the rolls, by using filter-cloth webs that prevent the undesirable passage of particles or fibres, provided that this increase m the size of the holes does not impair the support afforded to the filter cloth. In the case of the press described m SU-A-561 765, the filter-cloth webs move downwards and away from one another af- ter passing through the press nip and the concentrated material falls down into an underlying material transporter. This diver¬ gence of the webs downstream of the press nip results in a de¬ crease in the degree of compression or compaction of the mate¬ rial and there is an undesirable tendency for moisture or liq- uid that has already been pressed from the material oeing drawn back from the interior of the press rolls by suction. The ooπect of the present invention is to provide a novel and advantageous arrangement with which the aforesaid drawbacks are avoided to at least a substantial extent. With the intention of solving the aforesaid problems, it is proposed in accordance with the present invention that in a concentrator press of the kind defined in the introduction, the filter-cloth webs are caused to run generally parallel with one another downstream of the press nip, up to a concentrated mate- rial delivery station. This arrangement avoids re-wettmg of the concentrated material to a large extent. Further improve¬ ments are achieved in this respect in accordance with a pre¬ ferred embodiment of the invention in which the mutually paral¬ lel web sections extend upwards from the press rolls. Prefera- bly, the upper parts of the mutually parallel web sections are curved so as to deliver the concentrated material to one side of the press. This further reduces the risk of re-wetting the concentrated material and the material is obtained in the form of a coherent web of generally uniform thickness which can be subjected to a subsequent additional concentration stage for instance, in a simple and rational manner. Other characteristic features of the invention and advantages afforded thereby will be evident from the dependent Claims and also from the following description of preferred embodiments of the invention given by way of example only. Figs. 1 and 2 are schematic vertical cross-section views of a first and a second embodiment of an inventive concentrator press respectively. Those components and features that find mutual correspondence in the two Figures have been designated w th the same reference signs. The concentrator press illustrated in Fig. 1 includes two press rolls 1 which are partially submerged in a trough 2, which in the illustrated case is assumed to contain a pulp sus- pension 3 that is to be concentrated or de-watered. The pulp suspension is delivered through an inlet 4 with the aid of a delivery pump, not shown. The press rolls 1 typically include perforated or apertured mantle surfaces 5 and are each partially embraced in the aper¬ tured region thereof by a respective individual endless filter¬ cloth web 6, 7, e.g. a wire cloth of suitable plastic material. As evident from Fig. 1, at least those parts of the mantle sur- faces 5 of the rolls 1 that are immersed in the pulp suspension are surrounded by an associated filter-cloth web. The roll trunnions are journalled in the trough end walls, where at least one trunnion 8 of each press roll is tubular and con¬ nected to a pump or some other subpressure source (not shown) for the purpose of removing liquid that has entered the inte¬ rior of the rolls 1. Seals 9 act on the sides of the press rolls 1 remote from the press nip between the rolls 1 in a re¬ gion where the roll mantle surfaces are covered by an associ¬ ated filter-cloth web 6, 7. Although not shown, corresponding seals seal against the end surfaces of the rolls 1, so as to close the trough 2 and enable a overpressure to be conveniently maintained in the trough and therewith assist removal of liquid from the pulp suspension 3 in the trough 2 and into the inte¬ rior of the rolls 1. Each of the filter-cloth webs 6, 7 partially surrounding the rolls 1 runs around a web direction changing or guide roller 10. The filter-cloth webs move upwards from the roll nip to the guide rollers 10 essentially parallel with one another in the direction of the arrows 11. The reference numeral 12 identifies web stretching or tensioning rollers that can be brought into abutment with the webs 6, 7, whereas the reference numeral 13 identifies spray nozzles with which the webs are sprayed clean. When the concentrator press shown in Fig. 1 is working, the press rolls 1 are rotated in mutually opposite directions so that the mutually parallel sections of the webs 6, 7 will move upwards at the same time as the pulp suspension is delivered to the trough 2 under an overpressure and a subpressure s gener¬ ated in the interior of the rolls 1. The suspension is there- with drawn by suction towards those areas of the roll mantle surface that are embraced by the filter-cloth webs and immersed in the trough 2 and transported to and through the roll nip and de-watered therein, wherewith water departs through the hollow trunnions 8. The de-watered pulp 14 is transported upwards be- tween the mutually parallel web sections to a delivery station in which guide scrapers 15 lead the concentrated pulp into a material transporter 16 situated above the press rolls 1 at a distance therefrom. At least one press roll may be movable to¬ wards and away from the other so as to enable the size of the press nip to be adjusted, and the filter-cloth webs 6, 7 may be provided with conventional web restraining means (not shown) for preventing lateral movement of the webs. The embodiment illustrated in Fig. 2 corresponds essentially to the Fig. 1 embodiment and will therefore be described below solely with respect to the differences in the Fig. 2 embodi¬ ment. In the Fig. 2 embodiment, the filter-cloth guide roller 10 is also movable in a vertical direction to enable tension in the web 6 to be adjusted. Two direction changing rollers 17, 18 and a guide roller 19 are provided for the web 7, whereby the web sections moving parallel with one another are curved to the left in the Figure, such as to deliver the concentrated pulp 14 in the form of a coherent web of generally uniform thickness to one side of the press. In this case, one of the direction changing rollers 17, 18 is also movable generally horizontally for adjusting the tension in the web 7. The invention is not restricted to the aforedescribed and il ¬ lustrated exemplifying embodiments and can be implemented in any desired manner that lies within the scope of the inventive concept as defined in the following Claims.

Claims: CLAIMS 1. A concentrator press comprising a pair of rotatably driv¬ able press rolls (1) which are arranged for mutual coaction and which have apertured or perforated mantle surfaces (5) for re¬ moving liquid from a liquid-drenched material (3) to be concen¬ trated and advanced between the press rolls, wherein each of the press rolls (1) is embraced around a part of its periphery (5) , including at least the region where they act on the mate- rial undergoing concentration, by an endless filter-cloth web (6, 7) which also runs around at least one web direction chang¬ ing roller (10; 10, 17, 18) located at a distance from an asso¬ ciated press roll (1) and the still not concentrated liquid- drenched material (3) , characterized in that the filter-cloth webs (6, 7) downstream of the press nip run generally parallel with each other to a concentrated material delivery station (15, 16) . 2. A press according to Claim 1, characterized in that the mu- tually parallel running web sections extend upwards from the press rolls (1) . 3. A press according to Claim 2, characterized in that the mu¬ tually parallel running web sections function to deliver the concentrated material (14) to a material transporter (15) situ¬ ated above the press rolls (1) . 4. A press according to Claim 3, characterized in that the up¬ per parts of the mutually parallel running web sections are curved so as to deliver the concentrated material (14) to one side of the press. 5. A press according to any one of Claims 1-4, characterized in that each endless filter-cloth web (6, 7) coacts with a re- spective web-tensionmg roller (12) . 6. A press according to any one of Claims 1-5, characterized by means (13) for washing the filter-cloth webs (6, 7) in those regions in which the webs are out of contact with concentrated material or material to be concentrated. 7. A press according to any one of Claims 1-6, characterized in that the press rolls (1) are provided with means (8) for conducting liquid away from said rolls, said means preferably being connected to a source of subpressure. 8. A press according to any one of Claims 1-7, characterized in that the press rolls are partially immersed into a trough (2) having an inlet (4) for material to be concentrated. 9. A press according to Claim 8, characterized in that the in¬ terior of the trough (2) is sealed against the atmosphere and is placed under overpressure.

Inventors: HODEN EBBE, HODEN, EBBE
Applicants: HODEN EBBE, SUNDS DEFIBRATOR IND AB, HODEN, EBBE, SUNDS DEFIBRATOR INDUSTRIES AB
Application year: 1996
Main classification: B01D33
IPC codes: B01D33, B30B9, D21C9, D21F1