WO2000073579A1 - Cylindre de criblage pour presse a vis - Google Patents

Cylindre de criblage pour presse a vis Download PDF

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Publication number
WO2000073579A1
WO2000073579A1 PCT/SE2000/001047 SE0001047W WO0073579A1 WO 2000073579 A1 WO2000073579 A1 WO 2000073579A1 SE 0001047 W SE0001047 W SE 0001047W WO 0073579 A1 WO0073579 A1 WO 0073579A1
Authority
WO
WIPO (PCT)
Prior art keywords
screen plate
screen
support
screen cylinder
support rings
Prior art date
Application number
PCT/SE2000/001047
Other languages
English (en)
Inventor
Lennart Bergkvist
Original Assignee
Kvaerner Pulping Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kvaerner Pulping Ab filed Critical Kvaerner Pulping Ab
Publication of WO2000073579A1 publication Critical patent/WO2000073579A1/fr

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/18—De-watering; Elimination of cooking or pulp-treating liquors from the pulp
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp
    • D21D5/16—Cylinders and plates for screens
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water

Definitions

  • the present invention relates to a cost- optimized screen cylinder for dewatering woodpulp suspensions in accordance with the pre-characterizing clause of Claim 1, and to a method for producing such a screen cylinder in accordance with Claim 12.
  • screw presses are used in certain applications for the purpose of increasing the dry substance content of the fibre pulp by means of dewatering. These screw presses are available in various designs.
  • a common feature of these is that a screw rotates in a cylinder consisting of a screen plate.
  • the cylinder is filled with a pulp suspension of a certain consistency.
  • water is pressed out of the pulp and removed through holes in the plate cylinder.
  • the perforated screen plate in the screen cylinder is exposed to high axial and radial forces.
  • Existing constructions of screen cylinders have hitherto been based on a thick screen plate (ca 12 mm) which, because of its thickness, is provided with double-bored holes, which is costly. Double boring
  • US-A-2, 355, 091 describes a known arrangement for treating and removing chemicals from fibre pulp.
  • the arrangement is associated with problems of the type indicated above.
  • the arrangement consists of a screw press in which a press screw is surrounded by a thick- walled, perforated cylindrical plate through which the liquid being removed is pressed out.
  • the thick-walled, perforated plate lies in a housing and is anchored in the housing by means of intermediate ribs. These ribs are placed symmetrically around the circumferential surface of the perforated plate and have the main purpose of separating the arrangement into sections A - D, the screen plate in each section being completely free between the ribs.
  • US-A-3, 943, 034 describes another screw press for dewatering and homogenizing pulp.
  • the arrangement consists of a perforated, hollow screw surrounded by a thick-walled screen drum.
  • the liquid being dewatered from the pulp can pass out through the screen drum and also in through the screw.
  • the screen drum surrounding the screw and the screw itself have a conical shape.
  • the housing surrounding the screen drum is divided into two sections and the screen drum is anchored in the housing. The specification does not say anything about the thickness of the screen plate.
  • the screen plate Judging from its structure, the screen plate is exposed to considerable forces, for which reason it ought to be made of sheet metal of considerable thickness, and is therefore expensive.
  • the screen plate surrounding the screw is placed in such a way that it passes through two compartments which are separate from each other. In one compartment, liquid passes out through the screen plate. In the other compartment, steam is added to the pulp and liquid passes out through the hollow, perforated screw. This division into two compartments presumably makes it considerably difficult to replace the screen plate.
  • US-A-4, 582, 568 moreover describes a screw press for controlling the water content of a fibre suspension.
  • the arrangement consists of two parts: a thickener and a pulp press of the screen type.
  • the thickener consists of a screw surrounded by a cylindrical, thick-walled screen plate which lies in a cylindrical outer housing. The water which leaves the pulp passes through the screen plate. The pulp is driven from the thickener onwards to the pulp press, which is made up of a conical screw surrounded by a screen plate.
  • the housing which surrounds the pulp press has a sloping floor so that the water leaving through the screen plate will be able to run off.
  • the screen plate is anchored in the surrounding housing. The thickness of the screen plate is not specified.
  • the object of the present invention is to make available a screen cylinder which eliminates or at least minimizes the abovementioned problems.
  • One aim of the invention is to make available a screen cylinder for dewatering pulp, and a method for producing the screen cylinder, which screen cylinder and method ensure complete functionality of the screen cylinder at less cost and permit economic production.
  • a further aim of the invention is to make available a screen cylinder whose screen plate is easier to replace upon servicing. According to the invention, this is achieved by means of the features specified in the characterizing clause of Claim 1.
  • An important advantage of the invention is that the screen plate can be made very thin, which permits low costs for materials and easier working and also eliminates the need for double-bored holes.
  • the great advantage in terms of maintenance of the screen cylinder is that the whole structure together with support rings can be re-used. When the screen plate is worn, it can be removed and replaced, while the actual frame can be used again as a support for the new screen plate. This makes replacement and maintenance of the screen press much less expensive.
  • Fig. 1 is a perspective view of a screen cylinder
  • Fig. 2 is a coaxial view of a support ring
  • Fig. 3 is a perspective view of a spacer
  • Fig. 4 shows a detail from Fig. 1, with the support rings supporting a screen plate
  • Fig. 5 shows a dewatering arrangement with screen plates according to the prior art
  • Fig. 6 shows an alternative screen cylinder in divided form
  • Fig. 7 shows a detailed view of the connection element 71a from Figure 6
  • Fig. 8 shows a side view of the connection element shown in Figures 6 and 7.
  • the field of application of the invention is that of arrangements for dewatering woodpulp suspensions in accordance with Figure 5, comprising a displacement screw 2 arranged inside a screen cylinder.
  • the screen cylinder comprises, in a conventional manner, a number of sections with screen cylinders 1 which are combined to give the necessary dewatering length.
  • the woodpulp suspension is introduced via the inlet 3 and, under displacement of the rotating screw 2, liquid is pressed out radially through the screen plates for onward delivery to the liquid outlet 5.
  • the dewatered woodpulp suspension is obtained at the outlet 4.
  • a final dewatering is carried out at very high pressure.
  • a screen cylinder is designated generally by 1.
  • the screen cylinder 1 comprises a screen plate 20 in the form of a cylinder.
  • Support rings 30 lie on the screen plate 20.
  • the support rings 30 enclose the screen cylinder 1 about its circumferential surface.
  • the support rings 30 are held axially apart by means of spacers 50.
  • the support rings 30 are anchored in the end rings 60 by means of bars 40 which run coaxial with the screen cylinder 1, and by means of spacers 50 and corresponding holes in each support ring 30.
  • the external diameter of the bars is generally between 13 mm and 21 mm.
  • the bars are preferably hollow with an internal diameter generally of between 12 mm and 20 mm.
  • the screen plate 20 consists of a sheet of suitable metal, preferably stainless steel, provided with single-bored circular holes 21.
  • the screen plate 20 has a thickness of 2 to 6 mm. It is welded together along a weld seam 22 which runs axially along the screen cylinder 1.
  • a screen plate 20 forms a screen cylinder unit which can have a length of between 1 m and 2 m.
  • the screen cylinder 1 generally has an internal diameter (d) of between 0.7 m and 1.5 m, preferably 0.25 m to 2 m.
  • the support rings 30 are preferably laser-cut sheet metal rings for the purpose of achieving high precision.
  • the thickness of the support rings 30 is generally between 3 mm and 8 mm.
  • Formed in these support rings 30 there are a number of holes 31 which are spaced along the entire ring 30 at a mutual spacing of between 100 mm and 400 mm.
  • the internal diameter of the support ring 30 constitutes the size of the screen cylinder.
  • the height (h) of the support ring is between 50 mm and 100 mm.
  • the support rings 30 are arranged in a row about the circumferential surface of the screen cylinder 1.
  • the support rings 30 are separated from each other (by spacers 50) with a spacing of between 30 mm and 150 mm.
  • the number of support rings 30 per metre of screen cylinder is 5 - 35, preferably 10 - 25, and most preferably 15 - 20. In this way, it is possible to use a very thin screen plate which is unsupported across a relatively short distance between two adjacent support rings .
  • Fig. 3 shows the spacers 50 which consist of cylinders with a circular hole 51.
  • the spacer 50 has an internal diameter which is greater than the said bar 40 and an external diameter which is greater than the hole 31 in the support ring 30.
  • the internal diameter of the spacer 50 is the external diameter of the bar 40 plus 1 mm.
  • the internal diameter of the spacer 50 is generally between 14 mm and 22 mm.
  • the spacers 50 are preferably made of stainless steel and preferably have a thickness of at least 2 mm.
  • the bar 40 consists of a pipe or a rod and is preferably made of stainless steel, for example 2333, 2343 or duplex.
  • the bar 40 runs through the holes 31 in the support rings 30 and through the holes 51 in the spacers 50.
  • the bar 40 is fixed at each end to an end ring 60 via a threaded connection or a welded connection.
  • Fig. 1 shows the end ring 60, which preferably consists of a ring of the same material, i.e. stainless steel. It has an internal diameter adapted to the screen plate 20.
  • the end ring 60 preferably has a thickness of between 10 mm and 30 mm.
  • bolt holes 61 which are placed uniformly about the entire end ring. The distance between the bolt holes 61 on the end ring 60 is between 100 mm and 250 mm.
  • the bars 40 passing through the support rings 30 are fixed in these holes 61.
  • the bars 40 are fixed in the end rings 60 by screws or are fixed by welding.
  • Figure 4 shows an enlarged detail from Figure 1, with the support rings 30 arranged on the outside of the assembled screen plate 20.
  • the bars 40 pass through all the support rings, and the spacers 50 are arranged coaxially on the bars.
  • the spacers ensure that the support rings 30 are situated at a suitable distance from each other and that the screen plate thereby has the necessary support in the radial direction from the screen cylinder.
  • the screen plate 20 has been provided with double bores 21a and 21b, with a slightly larger bore size arranged furthest from the woodpulp suspension which is to be dewatered (the woodpulp suspension is conveyed underneath the screen plate in Figure 4) .
  • each individual screen section can be built up with unsupported areas between the end rings 60.
  • the support rings do not require any radially external support if the screen plate and support rings are suitably dimensioned.
  • the production of the screen cylinder 1 is illustrated on the basis of two different methods. Both of these methods for producing the screen cylinder 1 are divided into a number of stages.
  • the screen plate 20 is welded together, after which the screen plate 20 is shrunk radially, for example by cooling or local buckling, or, alternatively, the support rings are heated.
  • Support rings 30 are arranged on the outside of the screen plate 20, after which the screen plate 20 is expanded to engage them. This engagement can be obtained by the heated support ring structure being cooled, or by the locally deformed screen plate being allowed to resume its original shape in the radial direction.
  • Welding can be effected between support rings and screen plate before removal of a mandrel underpinning the screen plate .
  • the support arrangement 10 is pre-assembled, after which the screen plate is rolled up.
  • the rolled-up screen plate 20 is inserted into the hollow space in the free support arrangement 10, after which the screen plate 20 is expanded until support rings 30 of the support arrangement 10 bear against the entire circumferential surface of the fully expanded screen plate 20.
  • the screen plate 20 is then joined together by means of welding.
  • Figure 6 shows an alternative embodiment with a divided screen cylinder according to the invention, which facilitates repairs and replacement of individual screen cylinders in paper pulp dewatering constructions made up of a number of screen cylinders.
  • connection element 71 comprising a flat iron member 34a, 34b is welded into place 37 on both sides of a dividing plane 32 in each support ring half 30a, 30b.
  • the screen plate halves 20a, 20b are also welded in each support ring half 30a, 30b with intermittent welds 70 of suitable number on the dividing plane.
  • the screen plate halves are held together by a bolt and nut connection 35, 36 through the flat iron members 34a, 34b, preferably between every second support ring, as is shown in Figure 8.
  • the flat iron members can preferably be centred by means of a round rod 33 which is clamped securely between V-shaped grooves in the flat iron member.
  • each screen plate is arranged in the shrunk state on pre-assembled support rings, after which the screen plate is expanded against the support ring, followed by application of an intermittent weld 70 in association with the dividing plane 32.
  • the invention is not limited to the above embodiments, and instead it can be varied within the scope of the attached patent claims.
  • the bars can be made of different materials and with different geometrical cross sections. They can be solid or hollow.
  • the spacers can be integrated with the bars or can consist of separate elements which are fixed to the said bars.
  • the screen plate can of course be provided with holes other than by single boring.
  • the support ring can, for example, have bevels inwards towards the surface bearing against the screen plate in order, if so required, to reduce the bearing surface against the screen plate, which could be an obstacle for the liquid flowing out through the screen.
  • the attachment of the bars in the end rings can of course also be varied in a number of different ways. They can be fixed by welding or by screws. It will also be appreciated that a finished screw press according to the invention can consist of one or more combined screen sections, and not all the sections need necessarily be designed according to the invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)

Abstract

La présente invention se rapporte à un cylindre de criblage (1) conçu pour l'essorage d'une pâte à papier et à un procédé de fabrication de ce cylindre de criblage. Ce cylindre comporte une plaque de criblage (20) conçue pour envelopper une vis rotative qui force le liquide à traverser ladite plaque de criblage (20). Cette dernière est entourée par des anneaux de support (30) assemblés à des éléments de support (40) disposés parallèlement à l'axe du cylindre de criblage, lesdits anneaux de support (30) étant maintenus à distance les uns des autres au moyen de dispositifs écarteurs (50). L'invention permet l'utilisation d'une plaque de criblage mince (20) présentant une épaisseur comprise entre 1 et 6 mm, et de préférence entre 2 et 4 mm.
PCT/SE2000/001047 1999-05-26 2000-05-24 Cylindre de criblage pour presse a vis WO2000073579A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9901935-8 1999-05-26
SE9901935A SE515902C2 (sv) 1999-05-26 1999-05-26 Silcylinder till skruvpress och förfarande för att tillverka silcylindern

Publications (1)

Publication Number Publication Date
WO2000073579A1 true WO2000073579A1 (fr) 2000-12-07

Family

ID=20415765

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2000/001047 WO2000073579A1 (fr) 1999-05-26 2000-05-24 Cylindre de criblage pour presse a vis

Country Status (2)

Country Link
SE (1) SE515902C2 (fr)
WO (1) WO2000073579A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006130089A1 (fr) * 2005-06-03 2006-12-07 Metso Paper, Inc. Dispositif de traitement de la pate a papier dans un appareil de lavage equipe d'une cage d'armature
US8297445B2 (en) 2007-11-14 2012-10-30 Filtration Fibrewall Inc. Screen basket
US8469198B2 (en) 2005-05-09 2013-06-25 Kadant Canada Corp. Screen basket with replaceable profiled bars
CN105780574A (zh) * 2016-04-05 2016-07-20 李理 一种螺旋挤浆机的筛鼓制动装置
CN114164698A (zh) * 2021-12-14 2022-03-11 江苏金沃机械有限公司 具有非圆三防滑键结构的Half式非啮合双螺旋挤浆机

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1717604A (en) * 1927-10-04 1929-06-18 Anton J Haug Process and machine for thickening pulp
US2750855A (en) * 1951-12-20 1956-06-19 Elbert C Lathrop Dewatering of pulp
US4582568A (en) * 1983-09-15 1986-04-15 Beloit Corporation Apparatus for controlling the consistency of a pulp suspension
US4954249A (en) * 1988-06-10 1990-09-04 Beloit Corporation Wave screen plate

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1717604A (en) * 1927-10-04 1929-06-18 Anton J Haug Process and machine for thickening pulp
US2750855A (en) * 1951-12-20 1956-06-19 Elbert C Lathrop Dewatering of pulp
US4582568A (en) * 1983-09-15 1986-04-15 Beloit Corporation Apparatus for controlling the consistency of a pulp suspension
US4954249A (en) * 1988-06-10 1990-09-04 Beloit Corporation Wave screen plate

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8469198B2 (en) 2005-05-09 2013-06-25 Kadant Canada Corp. Screen basket with replaceable profiled bars
WO2006130089A1 (fr) * 2005-06-03 2006-12-07 Metso Paper, Inc. Dispositif de traitement de la pate a papier dans un appareil de lavage equipe d'une cage d'armature
US8556087B2 (en) 2005-06-03 2013-10-15 Metso Paper, Inc. Arrangement for the treatment of cellulose pulp in a washing apparatus arranged with a reinforcing frame
US8297445B2 (en) 2007-11-14 2012-10-30 Filtration Fibrewall Inc. Screen basket
CN105780574A (zh) * 2016-04-05 2016-07-20 李理 一种螺旋挤浆机的筛鼓制动装置
CN114164698A (zh) * 2021-12-14 2022-03-11 江苏金沃机械有限公司 具有非圆三防滑键结构的Half式非啮合双螺旋挤浆机

Also Published As

Publication number Publication date
SE515902C2 (sv) 2001-10-29
SE9901935L (sv) 2000-11-27
SE9901935D0 (sv) 1999-05-26

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