Classifications

• • 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
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
  • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
  • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
  • D21B1/30—Defibrating by other means
  • D21B1/32—Defibrating by other means of waste paper
• • 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
  • D21D5/023—Stationary screen-drums
  • D21D5/026—Stationary screen-drums with rotating cleaning foils
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/64—Paper recycling

Definitions

• the invention relates to a method for cleaning a pulp suspension containing contaminants, at least partially made of waste paper, with at least two closed sorters arranged in a row, in which the pulp suspension supplied via an inlet is sorted with a sieve by passing a flow of accepts through the respective sieve and the part retained by the sieve is discharged as a reject stream, the accepts and rejects streams being passed via a controllable valve immediately after the respective sorter and the rejects stream of a first sorter being led to the inlet of a second sorter without the interposition of a store.
• Fiber components that no longer contain any coarse contaminants can be drawn off as an accepted stream through the sieve in the sorter.
• the part rejected by the sieve mainly comes out of the sorter as a reject stream. Due to the increasing contamination of the waste paper, plaits and accumulations of plastic and other contaminants are increasingly forming in the inlet area in the area of the screen. This then leads to failures due to clogging and increased cleaning stoppages.
• the object of the invention is therefore to create a method with which it is possible to process paper raw materials with a high content of contaminants in an economical and operationally reliable manner.
• the object was achieved in that the valves of the reject flow of at least two sorters arranged in series are opened briefly and simultaneously to flush out accumulations of rejects from the sorters by means of the reject stream containing contaminants and fibers.
• valves of the reject flow should be reset to the value before the flushing after the reject accumulations have been flushed out.
• valves of the reject flow of the sorters following the first sorter in series are opened briefly and simultaneously. If the reject stream of several first sorters is fed to the inlet of a following, common second sorter, then the flushing out of accumulations of rejects from the first sorter should take place together with the second sorter with a time delay.
• valves of the reject flow of at least two sorters arranged in series are only used for a period of 2 to 5 s to be opened.
• valves of the material flow remain unchanged during the flushing out of reject accumulations.
• valves of the material flow of one or more sorters can also be advantageous to close the valves of the material flow of one or more sorters while the valves of the reject flow are opening by a predetermined value, preferably by up to 30%, in particular by a maximum of 20%.
• the sorter is designed as a pressure sorter and has a sieve element that is rotationally symmetrical about a sieve axis and divides the pressure sorter into an inlet space and an accepted material space, the inlet space with the suspension inlet and a reject outlet and the Accepts space is connected to an accept drain and a drum-like rotor with rotor blades is located in the inlet space, the axis of rotation of which corresponds to the sieve axis and which rotates relative to the sieve element.
• FIG. 1 a schematic cross section through a pressure sorter along the axis of rotation 19;
• FIGS. 2 and 3 different system schemes for presorting a stock preparation system of a paper machine.
• the closed sorters 2, 3, 4, 5 used here are designed as pressure sorters. However, at least individual sorters 2, 3, 4, 5 can also be designed as disk sorters, as described, for example, in DE 30 01 869 A1, ie with a disk-shaped sieve 7.
• pressure sorters 2, 3, 4, 5 have a screen 7 in the form of a cylindrical screen basket with a vertical screen axis 18, which divides the interior of the pressure sorter into an inlet space 12 and an accepted material space 13.
• the fiber suspension 1 is fed into the feed space 12 via a suspension feed 6.
• the pulp suspension 1 receives an angular momentum that sets it in a circumferential movement.
• a transport flow is generated.
• the part of the pulp suspension 1 rejected by the sieve 7 is conveyed as reject via the reject outlet 14 from the inlet space 12.
• a sieve scraper In order to prevent the openings of the sieve 7 from being clogged, a sieve scraper, known per se, is used, which moves relative to the sieve 7.
• This screen scraper is formed by a rotor 16 rotating in the screen 7 with rotor blades 17 attached thereto, the shape of which is only an example here.
• the rotor 16 has the shape of a cylindrical drum, the axis of rotation 19 coinciding with the sieve axis 18.
• a presorting system for cleaning a pulp suspension 1 that contains foreign matter and is formed at least partially from waste paper several closed sorters 2, 3, 4, 5 are arranged in series one behind the other.
• reject stream 9 of a sorter 2, 3, 4 is directed to the inlet 6 of a following sorter 4, 5.
• the accepts stream 8 passed through the corresponding screen 7 and the reject stream 9 rejected by the corresponding screen 7 are passed through a separate, controllable valve 10, 11.
• the flow rates of the sorter 2, 3, 4, 5 are set via these valves 10, 11.
• valves 10 of the material flow 8 remain unchanged.
• the system shown in FIG. 2 comprises, for example, only two sorters 2, 4 connected in series.
• the reject stream 9 of the first sorter 2 is directed to the inlet 6 of the second sorter 4 and the accepts streams 8 of both sorters 2, 4 are brought together.
• valves 11 of the reject streams 9 of both sorters 2, 4 containing contaminants and fibers are opened simultaneously over a period of 2 to 5 s.
• valves 11 of the reject streams 9 are then reset to the value before the flushing. Since there is no storage unit, for example a chute, between the first sorter 2 and the second sorter 4, the increased access of rejects can overload the second sorter 4.
• valve 11 of the reject flow 9 of the second sorter 4 is opened briefly and only this sorter 4 is flushed. Should further sorters 5 follow, this can be done analogously.
• the rinsing out of reject accumulations takes place with a time delay in the two rows of sorters 2, 3, 4, 5 connected one behind the other.
• valves 11 of the reject streams 9 containing contaminants and fibers in a first row of sorters 2, 4, 5 are opened simultaneously over a period of 2 to 5 s and then reset to the value before flushing.
• the second row of sorters 3, 4, 5 can be flushed out by simultaneously opening and then resetting the valves 11 of their reject streams 9 containing contaminants and fibers.

Landscapes

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=71738101

Family Applications (1)

Country Status (4)

Family Cites Families (8)

• 2019
  • 2019-09-20 DE DE102019125317.9A patent/DE102019125317A1/de active Pending
• 2020
  • 2020-07-14 EP EP20743613.0A patent/EP4031705A1/de active Pending
  • 2020-07-14 WO PCT/EP2020/069861 patent/WO2021052652A1/de unknown
  • 2020-07-14 CN CN202080065828.9A patent/CN114423899A/zh active Pending

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