WO1995010658A1 - Sealing strip for dewatering device with press rolls - Google Patents

Sealing strip for dewatering device with press rolls Download PDF

Info

Publication number
WO1995010658A1
WO1995010658A1 PCT/SE1994/000877 SE9400877W WO9510658A1 WO 1995010658 A1 WO1995010658 A1 WO 1995010658A1 SE 9400877 W SE9400877 W SE 9400877W WO 9510658 A1 WO9510658 A1 WO 9510658A1
Authority
WO
WIPO (PCT)
Prior art keywords
rolls
roll
vat
steel strip
seals
Prior art date
Application number
PCT/SE1994/000877
Other languages
French (fr)
Inventor
Bert HÄGGSTRÖM
Ingemar Sundqvist
Original Assignee
Sunds Defibrator Industries 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 Sunds Defibrator Industries Ab filed Critical Sunds Defibrator Industries Ab
Priority to AU79514/94A priority Critical patent/AU7951494A/en
Publication of WO1995010658A1 publication Critical patent/WO1995010658A1/en
Priority to FI961615A priority patent/FI961615A0/en

Links

Classifications

    • 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
    • D21F1/74—Pulp catching, de-watering, or recovering; Re-use of pulp-water using cylinders
    • D21F1/76—Pulp catching, de-watering, or recovering; Re-use of pulp-water using cylinders with suction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/06—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums
    • B01D33/073—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums arranged for inward flow filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/35—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition
    • B01D33/37—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition in parallel connection
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
    • B01D33/72—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2201/00—Details relating to filtering apparatus
    • B01D2201/34—Seals or gaskets for filtering elements

Definitions

  • This invention relates to a press for dewatering material suspensions, possibly in connection with liquid treatment.
  • a press comprises two co-operating press rolls, which between them ⁇ selves form a roll nip.
  • the rolls are arranged in a vat, to which the material suspension, for example a pulp suspension, is supplied.
  • the rolls are formed with liquid-permeable shell surfaces, and the suspension is dewatered in that liquid by means of overpressure is pressed in through these surfaces.
  • the final dewatering to the desired dry matter content of the material takes place in the nip between the rolls.
  • the dry matter content there can be up to 35-55%.
  • the shell surface of the press rolls consists of a perforated metal sheet welded on a roll body.
  • the total open area shall be large at the same time as the apertures shall be small to prevent fibers from following along with the liquid through the apertures.
  • the press roll is provided with a wire cloth on the outside of the perforated shell sheet.
  • the wire allows liquid flow even along the shell surface. This implies, that the perforations can be given a greater size so as to yield a higher capacity without causing the risk of increased fiber passage.
  • the use of press rolls covered with wire has proved to be especially advantageous for mechanical pulp, which contains a greater amount of fine material.
  • the wire cloth, compared with a perforated metal sheet, implies that a smaller amount of fine material is allowed to pass through.
  • the rolls immersed in the vat are rotary on two parallel shafts, so that the vat encloses at least the lower half of the rolls.
  • the material suspension is supplied to the space between the rolls and vat. This space is sealed toward the ambient, so that an overpressure can be maintained in the vat in order thereby to fac ⁇ ilitate dewatering.
  • Seals are provided at the upper edge of the vat both, toward the end walls of the rolls and along the shell surf ⁇ aces of the rolls.
  • the seal at the end walls normally consists of an hydraulically applied plastic strip, and to the shell surface, norm ⁇ ally a bar is applied, mostly by hydrostatic pressure. Between the rolls, the nip and the pulp web passing through continuously serve as a seal toward the ambient.
  • doctor means are located, the object of which is to remove the dewatered pulp web from the rolls.
  • the doctor means norm ⁇ ally comprise a steel or plastic blade, which abuts obliquely the • .shell surface of the roll.
  • the pulp is thereafter removed by means of a con ⁇ veyor for subsequent processing steps.
  • Fig. 1 is a cross-section of a press according to the invention, and Fig. 2 shows a sealing device on an enlarged scale.
  • the device shown in Fig. 1 comprises two cylindric rotary liquid- -permeable press rolls 10, the shell surface of which consists of a perforated metal sheet welded on a roll body. On the outside of the perforated sheet, a wire cloth 11 is applied which preferably is made of plastic wires.
  • the rolls 10 are partially immersed in a vat 12 so that spaces 13 are formed between the rolls and vat. Said spaces 13 communicate with inlets 14 for the pulp suspension. Between the rolls 10, the spaces 13 contract to form a nip 15.
  • the spaces 13 are sealed toward the ambient by seals 16 toward the shell surfaces of the rolls 10, and by seals 17 applied to the end walls of the rolls,
  • the pulp web in the nip 15 acts as a seal between the rolls.
  • the seal 16 between the vat 12 and the shell surface of each of the rolls 10 consists of a flexible steel strip 21 extending along the entire length of the roll.
  • the steel strip 21 is attached in a holder 20 on the upper edge of the vat 12, in such a manner that the strip is directed inward to the roll 10 and bent so that its leading end abuts the rolls.
  • a blade 19 of flexible seal ⁇ ing material, preferably rubber, is located on that side of the steel strip 21 which is remote from the roll, so that the blade 19 raises together with the steel strip and extends all the way to the roll.
  • the ' leading end of the steel strip 21 extends past the leading end of the blade 19 and can be designed with a clearance.
  • the blade 19 has a length in axial direction exceeding the axial length of the steel strip 21 so as to form a seal to the seals 17 at the end walls of the roll in the vat corners.
  • the seal 16 Due to the design of the seal 16, overpressure can be maintained in the space 13 without causing the risk of deformation of or damage on the wire cloth.
  • the seal has a simple and effective design and can easily be installed and replaced, when required. Normally, the seal ⁇ ing blade 19 and the steel strip 21 are replaced.

Abstract

A device for dewatering material suspensions, possibly in connection with liquid treatment. The device comprises two cylindric rotary liquid-permeable press rolls (10), the shell surface of which is covered with wire cloth (11). The press rolls are located in a vat (12) partially enclosing the rolls, which between themselves form a nip (15). Seals (16, 17) are provided in the vat (12), so that an airtight space (13) is formed between the rolls (10) and vat (12). The seals (16) along the shell surfaces of the rolls (10) consist of a flexible steel strip (21) attached on the upper edge of the vat (12) and extending inward to the shell surface of each roll (10). The steel strip (21) is bent in the rotation direction of the roll, so that its leading end abuts the roll.

Description

Sealing strip for dewatering device with press rolls.
This invention relates to a press for dewatering material suspensions, possibly in connection with liquid treatment.
A press comprises two co-operating press rolls, which between them¬ selves form a roll nip. The rolls are arranged in a vat, to which the material suspension, for example a pulp suspension, is supplied. The rolls are formed with liquid-permeable shell surfaces, and the suspension is dewatered in that liquid by means of overpressure is pressed in through these surfaces. The final dewatering to the desired dry matter content of the material takes place in the nip between the rolls. The dry matter content there can be up to 35-55%.
The shell surface of the press rolls consists of a perforated metal sheet welded on a roll body. In order to achieve high capacity, the total open area shall be large at the same time as the apertures shall be small to prevent fibers from following along with the liquid through the apertures. For solving these problems, the press roll is provided with a wire cloth on the outside of the perforated shell sheet. The wire allows liquid flow even along the shell surface. This implies, that the perforations can be given a greater size so as to yield a higher capacity without causing the risk of increased fiber passage. The use of press rolls covered with wire has proved to be especially advantageous for mechanical pulp, which contains a greater amount of fine material. The wire cloth, compared with a perforated metal sheet, implies that a smaller amount of fine material is allowed to pass through.
The rolls immersed in the vat are rotary on two parallel shafts, so that the vat encloses at least the lower half of the rolls. The material suspension is supplied to the space between the rolls and vat. This space is sealed toward the ambient, so that an overpressure can be maintained in the vat in order thereby to fac¬ ilitate dewatering. Seals are provided at the upper edge of the vat both, toward the end walls of the rolls and along the shell surf¬ aces of the rolls. The seal at the end walls normally consists of an hydraulically applied plastic strip, and to the shell surface, norm¬ ally a bar is applied, mostly by hydrostatic pressure. Between the rolls, the nip and the pulp web passing through continuously serve as a seal toward the ambient.
After the nip, doctor means are located, the object of which is to remove the dewatered pulp web from the rolls. The doctor means norm¬ ally comprise a steel or plastic blade, which abuts obliquely the •.shell surface of the roll. The pulp is thereafter removed by means of a con¬ veyor for subsequent processing steps.
It was found that the use of sealing bars of the type normally used at press rolls with shell surfaces of perforated metal sheet is not at all suitable at press rolls covered with wire cloth. There is a great risk that the wire cloth gets wedged and deformed and that at the same time the efficiency decreases.
The present invention offers a solution for the aforesaid problems. The characterizing features of the invention are apparent from the attached claims.
The invention is described in greater detail in the following, with reference to an embodiment thereof shown in the accompanying drawing, in which
Fig. 1 is a cross-section of a press according to the invention, and Fig. 2 shows a sealing device on an enlarged scale.
The device shown in Fig. 1 comprises two cylindric rotary liquid- -permeable press rolls 10, the shell surface of which consists of a perforated metal sheet welded on a roll body. On the outside of the perforated sheet, a wire cloth 11 is applied which preferably is made of plastic wires. The rolls 10 are partially immersed in a vat 12 so that spaces 13 are formed between the rolls and vat. Said spaces 13 communicate with inlets 14 for the pulp suspension. Between the rolls 10, the spaces 13 contract to form a nip 15.
The spaces 13 are sealed toward the ambient by seals 16 toward the shell surfaces of the rolls 10, and by seals 17 applied to the end walls of the rolls, The pulp web in the nip 15 acts as a seal between the rolls.
After the nip 15, doctor means 18 are located to remove the pulp web coming from the nip 15. The seal 16 between the vat 12 and the shell surface of each of the rolls 10 consists of a flexible steel strip 21 extending along the entire length of the roll. The steel strip 21 is attached in a holder 20 on the upper edge of the vat 12, in such a manner that the strip is directed inward to the roll 10 and bent so that its leading end abuts the rolls. A blade 19 of flexible seal¬ ing material, preferably rubber, is located on that side of the steel strip 21 which is remote from the roll, so that the blade 19 raises together with the steel strip and extends all the way to the roll. The' leading end of the steel strip 21 extends past the leading end of the blade 19 and can be designed with a clearance. The blade 19 has a length in axial direction exceeding the axial length of the steel strip 21 so as to form a seal to the seals 17 at the end walls of the roll in the vat corners.
Due to the design of the seal 16, overpressure can be maintained in the space 13 without causing the risk of deformation of or damage on the wire cloth. The seal has a simple and effective design and can easily be installed and replaced, when required. Normally, the seal¬ ing blade 19 and the steel strip 21 are replaced.
The invention, of course, is not restricted to the embodiment shown and described, but can be varied within the scope of the invention idea.

Claims

Claims
1. A device for dewatering material suspensions, possibly in connection with liquid treatment, comprising two cylindric rotary liquid permeable press rolls (10), the shell surface of which is covered with wire cloth (11), and where the press rolls are located in a vat (12), which partially encloses the rolls, where the rolls (10) between themselves form a nip (15), and seals (16,17) are provided in the vat (11) so that an airtight space (13) is formed between the rolls (10) and vat (12) c h a r a c t e r i z e d i n that the seals (16) along the shell surfaces of the rolls (10) consist of a flexible steel strip (12), which is attached at the upper edge of the vat (12) and extends inward to the shell surface of each roll (10), which steel strip (21) is bent in the rotation direction of the roll so that its leading end abuts the roll, and a flexible blade (19) located on that side of the steel strip (21) which is remote from the roll, so that it is bent together with the steel strip (21) and extends all the way to the roll, the leading end of the steel strip (21) extending past the leading end of the blade (19) .
2. A device as defined in claim 1, c h a r a c t e r i s e z i n that the leading end of the steel strip (21) is formed with a clearance.
3. ' A device as defined in claim 1 or 2, c h a r a c t e r i z e d i n that the blade (19) has a length in axial direction of the roll (10) exceeding the axial length of the steel strip (21), so that the blade (19) seals toward seals (17) at the end walls of the roll (10) in the corners of the vat (12) .
PCT/SE1994/000877 1993-10-14 1994-09-23 Sealing strip for dewatering device with press rolls WO1995010658A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU79514/94A AU7951494A (en) 1993-10-14 1994-09-23 Sealing strip for dewatering device with press rolls
FI961615A FI961615A0 (en) 1993-10-14 1996-04-12 Sealing tape for dewatering mechanism with press rollers

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9303381A SE503010C2 (en) 1993-10-14 1993-10-14 Seal for dewatering device with press rolls
SE9303381-9 1993-10-14

Publications (1)

Publication Number Publication Date
WO1995010658A1 true WO1995010658A1 (en) 1995-04-20

Family

ID=20391427

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1994/000877 WO1995010658A1 (en) 1993-10-14 1994-09-23 Sealing strip for dewatering device with press rolls

Country Status (4)

Country Link
AU (1) AU7951494A (en)
FI (1) FI961615A0 (en)
SE (1) SE503010C2 (en)
WO (1) WO1995010658A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5970862A (en) * 1997-06-09 1999-10-26 Sunds Defibrator Industries Ab Seal in a roll press
WO2000079039A1 (en) * 1999-06-18 2000-12-28 Kvaerner Pulping Ab Sealing arrangement for a pulp dewatering arrangement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE0102811L (en) * 2001-08-23 2003-04-24 Metso Paper Inc Seal on press rolls

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3772144A (en) * 1971-04-14 1973-11-13 Improved Machinery Inc Apparatus and method for thickening and washing suspensions containing fibrous material
US3980518A (en) * 1974-03-04 1976-09-14 Sunds Aktiebolag Device for liquid-treating a running fiber web, including an arc-shaped duct

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3772144A (en) * 1971-04-14 1973-11-13 Improved Machinery Inc Apparatus and method for thickening and washing suspensions containing fibrous material
US3980518A (en) * 1974-03-04 1976-09-14 Sunds Aktiebolag Device for liquid-treating a running fiber web, including an arc-shaped duct

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5970862A (en) * 1997-06-09 1999-10-26 Sunds Defibrator Industries Ab Seal in a roll press
WO2000079039A1 (en) * 1999-06-18 2000-12-28 Kvaerner Pulping Ab Sealing arrangement for a pulp dewatering arrangement

Also Published As

Publication number Publication date
AU7951494A (en) 1995-05-04
FI961615A (en) 1996-04-12
FI961615A0 (en) 1996-04-12
SE9303381D0 (en) 1993-10-14
SE9303381L (en) 1995-04-15
SE503010C2 (en) 1996-03-11

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