Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B9/00—Presses specially adapted for particular purposes
  • B30B9/02—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material
  • B30B9/20—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using rotary pressing members, other than worms or screws, e.g. rollers, rings, discs
• • 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

Definitions

• the present invention relates to a roll body for a press roll for dewatering pulp, comprising a central drum and several frame rings, to which at least one perforated roll plate is intended to be attached, the frame rings being distributed along the length of the central drum, and to a roll press comprising at least one press roll provided with said roll body.
• a roll press When producing cellulose-based products, a roll press is frequently pre- sent for dewatering the cellulose-based pulp.
• the pulp is passed between two cooperating press rolls in a roll press, the press rolls having a perforated envelope surface, whereby the envelope surface is permeable to water pressed out of the pulp, and is pressed in the press nip between the press rolls, whereby water is pressed out of the pulp.
• a roll press for dewatering pulp is disclosed in SE 505 539, e.g., where the central axes of the press rolls are lying in substantially the same horizontal plane, and the pulp is passing the press nip between the press rolls in a vertical direction, from below upwards.
• SE 519 753 describes a sealing of a press roll in a roll press having two co-operating press rolls for dewatering material suspensions.
• the above mentioned roll presses have in common that their roll bodies have a conventional structure, where the roll body comprises a longitudinal central drum, which can comprise a drum or an inner drum covered with a covering plate, or the like.
• the central drum is provided with several supporting ribs arranged longitudinally along the longitudinal axis of the central drum and evenly distributed along the circumference of the central drum. The purpose of these supporting ribs is to strengthen the structure, and also to provide channels which axially guide liquid pressed out of the pulp to the ends of the press roll.
• the liquid which after the press nip flows back through the roll plate and dilutes the pressed pulp especially for roll presses where the pulp is passed through the press nip between two press rolls in a vertical direction from below upwards, such as in SE 505 539, and also regarding the lower press roll for roll presses, where the pulp is passed in a substantially horizontal direction through the press nip between an upper and a lower press roll, the central axes of which are lying in different horizontal planes.
• the result of this rewetting is that the resulting dryness of the pressed pulp from the roll press is lower, and that the pulp is contaminated by lye or liquid previously pressed out.
• prior art roll bodies a drawback to prior art roll bodies is that this passage of liquid downwards in a vertical direction, inside the perforated roll plate, is limited due to the longitudinal supporting ribs, whereby the reduction of the rewetting is not effective enough.
• the construction of prior art roll bodies is complicated and consists of several construction articles, which results in a complicated manufac- turing of the roll body, involving several welding and shrinking steps, and consequently, also a complicated manufacturing of the press roll, and a high manufacturing cost due to this.
• the object of the present invention is thus to provide a roll body which pro- vides a press roll having a minimized rewetting, and which is less complicated and less expensive to manufacture compared to conventional roll bodies, especially for roll presses where the pulp is passing the press nip between two press rolls in a vertical direction from below upwards, and regarding the lower press roll of a roll press where the pulp is passing the press nip between an upper and a lower press roll in a substantial horizontal direction. Further, the purpose is to provide a roll press which achieves a minimized rewetting and which is also less complicated and less expensive to manufacture compared to conventional roll presses.
• a roll body of the kind defined in the preamble of claim 1 and a roll press of the kind defined in the preamble of claim 7, where a roll body comprises the special features that each frame ring is attached directly to the central drum, and is provided with at least one recess, whereby a passage in the axial direction is provided for the transport of liquid to the ends of the roll body. If the central drum comprises a covering sheet, naturally, each frame ring is attached to the covering sheet.
• a press roll is provided, having minimized rewet- ting since the construction makes it possible to omit the supporting ribs, whereby the fall downwards of expressed liquid, inside the perforated roll plates, no longer is restricted by said supporting ribs, especially for roll presses where the cellulose- based pulp is passing the press nip between two press rolls in a vertical direction, from below upwards, and regarding the lower press roll of roll presses where the pulp is passing the press nip between an upper and a lower press roll, in a sub- stantial horizontal direction.
• a roll press having a minimized rewetting is provided.
• the roll body of the present invention is also less complicated in its construction, and has fewer construction articles, which results in fewer manufacturing steps, which in turn results in lower manufacturing costs of the roll body, the press roll and, consequently, also of the roll press.
• each recess is adjacent to the central drum, which results in that liquid pressed out of the pulp is more easily transported in the axial direction, and thereby further reduces the rewetting.
• the recess of each frame ring is axially aligned with the recess of the adjacent frame ring, whereby an axially continuous passage through the frame rings is provided, which further facilitates the transportation of liquid in the axial direction.
• each frame ring is provided with several recesses distributed along the circumference of the frame ring. By this, the transportation of liquid in the axial direction is made yet more effective.
• the roll body of at least one of the press rolls comprises the further special features mentioned in any of the claims 2 to 6.
• the roll press is arranged to pass the pulp between the two press rolls in a vertical direction from below upwards, where the roll body of both press rolls comprises the special features mentioned in any of the claims 1 to 6.
• said two press rolls form a lower press roll and an up- per press roll, respectively, of the roll press, where the roll body of the lower press roll comprises the special features mentioned in any of the claims 1 to 6.
• the central axis of the upper press roll is lying in a horizontal plane above the horizontal plane in which the central axis of the lower press roll lies, whereby the pulp is fed more horizontally than vertically between the press rolls.
• This roll press can also comprise a conveying belt for the pulp, which runs between the press rolls.
• Fig. 1 is a schematic cut-away view of a conventional press roll having a conventional roll body
• Fig. 2 is a schematic partial sectional view of a conventional roll body
• Fig. 3 is a schematic partial sectional view of an embodiment of a roll body according to the present invention
• Fig. 4 is a schematic partial top view of the frame rings of the roll body of
• Fig. 5 is a sectional view of an embodiment of the roll press according to the present invention.
• Fig. 1 shows in section a conventional press roll comprising a conventional roll body.
• the roll body comprises a longitudinal central drum 1 , to the ends of which attachment means 2 are attached for the pivotal mounting in a roll press.
• To the envelope surface of the central drum 1 several longitudinal supporting ribs 3 are attached by welding.
• Several flat bars 4 are welded to several frame rings 5 at the inside of said frame rings 5, so that the frame rings 5 are positioned in succession with a suitable distance apart and distributed along a distance corresponding to the length of the central drum 1.
• the flat bars 4 are extending transversely to the frame rings 5 at their inside, and form, together with the frame rings 5, a kind of "cage".
• Fig. 2 shows a partial sectional view of a conventional press roll, illustrating in more detail the attachment of the frame rings 2.5 to the central drum 2.1 , by means of the longitudinal supporting ribs 2.3 and the flat bars 2.4.
• Fig. 3 shows a partial sectional view of an embodiment of a roll body ac- cording to the present invention.
• Several frame rings 7 are attached directly to the central drum 8 of the roll body, and each frame ring 7 is provided with several through holes/recesses 9.1 , 9.2, 9.3 distributed over the circumference of the frame ring 7, which provide a passage in the axial direction for the transport of liquid to the ends of the roll body.
• the extension of the frame rings 7 in the radial di- rection is considerably greater compared to conventional frame rings, which in the roll body according to the present invention results in an effective "height of fall" of the expressed liquid after the passage through the perforated roll plate, due to the absence of the conventional supporting ribs.
• Fig. 4 shows a schematic partial top view of the frame rings of the roll body of Fig. 3.
• Each frame ring 7, 7.1 , 7.2, 7.3, 7.4 is attached to an adjacent frame ring 7, 7.1 , 7.2, 7.3, 7.4 by means of several welded intermediate members 11.1 , 11.2, 11.3, 11.4 to provide a rigid construction.
• the frame rings can be fixed in relation to each other in any other way, by screw joint reinforcement, shrinking etc., for example.
• Fig. 5 shows an embodiment of the roll press according to the present invention, comprising a first press roll 12 and a second press roll 13, the longitudinal central axes of which are lying in substantially the same horizontal plane, each press roll comprising a roll body according to the present invention, where respec- tive frame ring 14, 15 is attached directly to respective central drum 16, 17.
• Perforated roll plates 18, 19 are abutting against the frame rings 14, 15.
• the pulp 20 is fed in through an inlet 21 and pressed up towards a press nip 22 between the first and the second press roll 12, 13, the rotation of which is indicated by vertically pointing arrows, the pulp 20 being dewatered and further pressed vertically upwards.
• the liquid pressed out of the pulp 20 in the press nip 22, which has permeated through the holes of the roll plates 18, 19, can more easily fall downwards compared to conventional roll presses, whereby the rewetting is effectively reduced.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)
• Rolls And Other Rotary Bodies (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

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ID=34075258

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (3)

• 2004
  • 2004-12-22 SE SE0403129A patent/SE528002E/sv not_active IP Right Cessation
• 2005
  • 2005-11-17 CA CA2589534A patent/CA2589534C/en not_active Expired - Fee Related
  • 2005-11-17 WO PCT/SE2005/001732 patent/WO2006068569A1/en active Application Filing
  • 2005-11-17 EP EP05803702A patent/EP1831456B1/en not_active Not-in-force

Patent Citations (3)

Non-Patent Citations (1)

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