GB2122111A

GB2122111A - A rotatable sorter drum

Info

Publication number: GB2122111A
Application number: GB08312668A
Authority: GB
Inventors: Helmut Konecsny
Original assignee: JM Voith GmbH
Current assignee: JM Voith GmbH
Priority date: 1982-06-09
Filing date: 1983-05-09
Publication date: 1984-01-11
Also published as: DE3221788C1; FI832064L; FR2528330A1; SU1237086A3; FI832064A7; GB8312668D0; JPS58220890A; FI832064A0; GB2122111B

Abstract

A sorter drum is constructed with a perforated casing and is rotatable around a horizontal axis, for sorting waste paper fibrous suspension containing coarsely pulped waste paper loaded with all the coarse impurities from the waste paper bales, and has perforation sizes of more than 5 mm diameter. The suspension is introduced via one end wall of the sorter drum and the liquid waste is extracted via the other end wall, while the good pulp stock is drawn off through the perforations. The casing of the sorter drum has at least two different sets of perforations, the hole width of which differs by more than 2.5 mm, following one after the other in the axial direction, the drum section (2) with the finer perforations being disposed at the inlet and (4) of the sorter drum (1). <IMAGE>

Description

SPECIFICATION Rotatable sorter drum and waste paper processing plant incorporating such a drum The invention relates to a sorter drum constructed with a perforated casing and rotatable about a horizontal axis, for sorting waste paper fibrous suspension containing coarsely pulped waste paper loaded with all the coarse impurities from the bales of waste paper, with perforation sizes of more than 5 mm diameter, the introduction of-th.e.-suspension being.effected via one end wall of the sorter drum and the extraction of the liquid waste being effected via the other end wall, and the pulp stock being drawn off through. the perforations.

A-sorter drum of this kind was made known in German Patent Specification No. 25 47 896.

According to this, a fine fraction of a waste paper suspension is drawn off through the perforations in the circumferential wall of the drum and a coarse fraction is drawn off through the axial connection in the end wall of the drum lying opposite the inlet opening. However, in practice this only makes it possible to draw off predominantly liquid waste via the end wall of the drum, which by then has only a relatively low fibre content, while on the other hand there is also the danger that the good pulp stock drawn off through the circumferential wall of the drum will be relatively heavily soiled, since the hole width of the perforations has been made much too large.

Owing to the different qualities of waste paper which are introduced into the pulper which is generally connected in front of the sorter drum, it is not possible in practice to provide an appropriate adjustment to suit all instances. It is therefore the object of the invention to provide a drum which takes account of the aim of producing a good pulp stock which has been as well cleaned as possible, and also of keeping the loss of fibre at the liquid waste extraction point in the end wall of the drum as slow as possible.

This object is achieved in a sorter drum of the kind described in the introduction with the features in the characterising section of Patent Claim 1.

An advantageous development of the appliance according to the invention is set out in Claim 2, and an advantageous plant and application of such a sorter drum is set out in Claim 4.

In the following the invention is described with reference to one embodiment of strainer drum according to the invention as shown in the Figure of the accompanying drawing, which is a crosssection through the drum.

In the Figure, the inlet opening into the sorter drum is designated 4 and the outlet hole in the end wall thereof opposite the inlet hole is designated 5. The two sections of the drum which differ from each other with regard to the perforation of the drum casing are designated 2 and 3, the section 2 adjacent to the inlet hole 4 being the section with the finer perforations, i.e.

the lesser hole width. The hole width amount to between 7 and 12.5 mm in the more finely perforated section, and to between 10 and 30 mm in the other section. According to a sorter device described in "Wochenblatt fur Papierfabrikation" (Weekly News-sheet for Paper Making), 1981, pages 927 to 930, with a sorter drum similar to the invention, a hole width of 18 mm was provided throughout for the perforations in the strainer drum, with a pulp consistency of between 4 and 6%. Consequently, according to the invention a much finer hole width is used on the inlet side. It is also surprising that the desired favourable effect is produced according to the invention by arranging the section of the drum with the fine perforations on the inlet side of the drum and the other section of the drum on the liquid waste side.Until now, in all known sorter devices for processing waste paper the larger hole widths were provided right at the beginning and were gradually replaced by increasingly fine hole widths.

The fibrous suspension produced from the waste paper is supplied to the sorter drum via a chute 42, for example, from a pulper. The sorter drum rotates around a horizontal axis and is mounted for this purpose via rails 6 on runner 7 which are shown in dashes. The drive is effected via a spur gear wheel 47 by means of a motor 48, via a pinion 49 and an intermediate gear wheel 50, to reduce the high rotary speed of the motor.

A mating wheel 1 5 which is set up above the drum on the front rail 6 accommodates the bending moment produced by the drum and its contents. This means in fact that the drum needs to be supported at only one of its ends. On the inside the drum has ribs 11 with a rolling effect; these are parallel to its axis of rotation and convey the waste paper suspension continuously upwards, thus causing the sump layer located at the bottom of the drum to be broken up.The swash plate 12 which is made in the form of an obliquely disposed ring and acts as a partition between the two sections 2 and 3 of the drum has a damming effect on the suspension in the first section 2 of the drum, and the transfer of the suspension into the section 3 of the drum is effected in that the suspension supplied by the rolling rib 11 directly in the vicinity of the swash plate 12 overcomes the barrier created by the swash plate in the setting shown.

Different consistencies can now be set up in the two drum sections; more specifically, it is possible to operate in the first section 2 of the drum with a lower consistency than in the second section 3 of the drum. Due to the relatively finer perforations in the section 2 of the drum a relatively well-cleaned pulp stock is strained into the appropriate compartment 1 3 of the trough 30 disposed beneath the strainer drum. Owing to the larger hole width of the perforations, a pulp stock is obtained in the compartment 1 9 of the trough which appertains to the section 3 of the drum which is still very heavily loaded with specks, and which must be processed further in the overall process in suitably effective sorter devices or combined pulper/sorter devices which effect appropriate de-specking.The pulp drawn off here can also be sent through a device which has become known specifically as a de-specking device. On the other hand, the pulp stock drawn off from the compartment 13 needs only be processed in sorter devices or in combined sorter/pulper devices in which de-specking is carried out at most only to a very limited extent.

Naturally, this consequently results in the optimum use of the processing plant developed for the various purposes.

The liquid required to dilute the waste paper suspension in the strainer drum is supplied through the distributor pipe 14 equipped with spray holes 1 6, outside the casing of the drum.

However, similar distributor pipes could also be provided inside the sorter drum. The liquid waste rejected out via the liquid waste end is carried away by means of a conveyor belt 51 mounted on rollers 52. Here, guide plates 53 prevent the liquid waste from falling off the sides. If the consistency of the liquid waste should be too thin, then naturally the conveyor belt 51 would have to be replaced by a trough out of which the suspension could then be pumped. The removal of the liquid waste is facilitated due to the fact that the axis of rotation of the drum is disposed sloping slightly down towards the liquid waste end.

Claims

1. A sorter drum constructed with a perforated casing and rotatable about a horizontal axis, for sorting waste paper fibrous suspension containing coarsely pulped waste paper loaded with all the coarse impurities from the bales of waste paper, with perforation sizes of more than 5 mm diameter, the introduction of the suspension being effected via one end wall of the sorter drum and the extraction of the liquid waste being effected via the other end wall, and the pulp stock being drawn off through the perforations, characterised by at least two different sets of perforations, the hole width of which differs by more than 2.5 mm, following one after the other in the axial direction, the section of the drum with the finer perforations being disposed at the inlet end of the sorter drum.

2. A sorter drum according to Claim 1, characterised in that the perforations in the first section of the drum with the smaller hole size have hole widths between 7 and 12.5 mm, and the perforations in the other section of the drum have hole widths betweeri 10 and 30 mm.

3. A sorter drum constructed, arranged and adapted for use substantially as hereinbefore described with reference to the Figure of the accompanying drawing.

4. A processing plant for waste paper of the kind using a sorter drum which is constructed with a perforated casing and can be rotated about a horizontal axis, characterised in that the strainer drum is as claimed in Claim 1, 2 or 3, in that the waste paper is pulped in a pulper to a consistency of more than 8% and is first diluted in the drum section with the finer perforations and then is cleansed of the coarse material in the adjoining drum section, and in that the waste paper suspension subjected to preliminary cleaning in the first and second sections of the drum is processed further separately in strainer-sorter devices, the pulp stock from the first section of the drum being processed in at least one strainersorter device with sorter bars or blades rotating along a rotationally symmetrical strainer basket, without a significant de-specking effect, and the pulp stock from the subsequent drum section being processed in at least one strainer-sorter device with turbulent flow occasioned by a rotor, with a strong de-specking effect.