EP2112272A1 - Procédé et appareil pour le nettoyage intégré d'une installation de traitement de pâte à papier - Google Patents

Procédé et appareil pour le nettoyage intégré d'une installation de traitement de pâte à papier Download PDF

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Publication number
EP2112272A1
EP2112272A1 EP08155077A EP08155077A EP2112272A1 EP 2112272 A1 EP2112272 A1 EP 2112272A1 EP 08155077 A EP08155077 A EP 08155077A EP 08155077 A EP08155077 A EP 08155077A EP 2112272 A1 EP2112272 A1 EP 2112272A1
Authority
EP
European Patent Office
Prior art keywords
separator
rejected
plant
prior
liquid
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP08155077A
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German (de)
English (en)
Inventor
Francis Mondon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Industrial Technology and Services LLC
Original Assignee
Industrial Technology and Services LLC
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 Industrial Technology and Services LLC filed Critical Industrial Technology and Services LLC
Priority to EP08155077A priority Critical patent/EP2112272A1/fr
Priority to US12/386,913 priority patent/US20090272504A1/en
Publication of EP2112272A1 publication Critical patent/EP2112272A1/fr
Withdrawn legal-status Critical Current

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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
    • 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
    • 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

Definitions

  • the present invention relates to a method and apparatus for the integrated cleaning of a paper-pulp processing plant used primarily, but not exclusively, for the production of corrugated paper and cardboard
  • the invention is particularly concerned with the cleaning of a plant used for processing paper-pulp produced from recycled paper and cardboard.
  • an aqueous suspension containing cellulosic fibres, and optional fillers and additives is fed through pumps, screens and cleaners, which subject the stock to high shear forces
  • the resulting pulp is fed into a headbox which ejects the suspension onto a forming wire.
  • Water is drained from the suspension through the forming wire so that a wet web of paper is formed on the wire, and the web is further dewatered and dried in the drying section of the paper machine.
  • Drainage and retention aids are conventionally introduced at different points in the flow of the suspension in order to facilitate drainage and increase adsorption of fine particles such as fine fibres, fillers and additives onto the cellulose fibres so that they are retained with the fibres on the wire.
  • Examples of conventionally used drainage and retention aids include organic polymers, inorganic materials, and combinations thereof.
  • Recycled paper and cardboard can be used to produce pulp for use in the above process.
  • the pulp produced tends to have a higher content of anionic impurities, typically colloidal impurities, than wood pulp.
  • anionic colloids has an adverse effect on the paper production process.
  • the impurities are unable to attach themselves to the fibres of the pulp in the suspension, which are also anionically charged, and in time tend to accumulate in the equipment comprising the production cycle. This interferes with the production process in a negative way. Firstly, it decreases the quality of the paper produced, for example by producing holes, dark spots and a reduction in the mechanical resistance of the paper.
  • the aqueous suspension containing cellulosic fibres which is hereinafter referred to as the 'stock' is subjected to treatment in a plurality of different baths.
  • the rejected flows egressing from these baths are also treated to recover fibres that can be re-introduced into the stock in order to reduce undue wastage of material.
  • the recovered liquid is also recycled back into the plant at the beginning of the pulping process. It would, therefore, be advantageous for a cleaning arrangement to be incorporated into a conventional processing plant whereby these anionic colloids and other similar colloidal material can be removed from the plant as part of an integrated process.
  • the object of the present invention is to provide such a method and apparatus for the integrated cleaning of a paper-pulp processing plant in order to remove or substantially reduce the quantity of pollutants, specifically anionic colloids, from said plant.
  • integrated cleaning means that the cleaning process is integrated into the pulp processing process and operates continuously as the pulp processing is in operation rather than being a separate cleaning process that is carried out during downtime of the plant.
  • a method for the integrated cleaning of a paper-pulp processing plant including one or more high density cleaners comprising the steps of supplying the rejected flow from one of said high density cleaners to a screening centrifugal separator; screening out contaminants in the separator using a screen hole size of less than 3.5 mm; thickening any fibrous material accepted by the separator and returning same to stock being processed in the processing plant; and recovering liquid from any material rejected by the separator prior to disposing of said material.
  • the contaminants in the separator are screened using a screen hole size of approximately 2.5 mm. This ensures that colloidal pollutants are screened out of the liquid which is recovered from the separator prior to its return to the stock
  • a paper-pulp processing plant including one or more high density cleaners and incorporating apparatus for the integrated cleaning of same, said apparatus comprising a screening centrifugal separator set up to receive the rejected flow from one of said high density cleaners and adapted to screen out contaminants from the rejected flow using a screen hole size of less than 3.5 mm; a thickener for thickening any fibrous material accepted by the separator and returning same to stock being processed in the processing plant; and means for recovering liquid from any material rejected by the separator prior to disposal of said material.
  • the rejected flow from the final high density cleaner in a conventional pulp processing plant is subjected to a cleaning process prior to its reintroduction into the stock at the commencement of the process.
  • the cleaning process is, therefore, integrated into the pulp processing process as a whole.
  • the rejected flow from the final high density cleaner in a conventional pulp processing plant is subjected to a cleaning process as will now be described with reference to Fig. 1 .
  • the rejected flow 10 is supplied to a screening centrifugal separator 11 that preferably comprises a conventional 'Separplast' separator that has been modified as described below.
  • Separplast separators were designed to separate light contaminants such as plastics, polystyrene, hot melts and the like originating from recycled paper waste from stock. Conventionally, in a paper-pulp processing plant a Separplast separator is positioned after the pulper and the high density cleaner. The accepted flow is then recycled back to the pulper and the rejected flow is thickened for disposal They are not, however, designed to remove colloidal waste
  • Centrifugal separators operate by rotating a cylinder carrying rotor blades at high peripheral speed inside a perforated basket.
  • the rotor typically has an overall diameter of 997 mm.
  • the rejected flow enters the separator 11 at the top from a constant level box 12 which regulates the flow and is provided with an on/off valve (not shown). Within the separator 11 the flow passes down through the rotor blades and the basket where it is deflaked and screened.
  • Lateral sprinklers spray clarified washing water onto the basket to lubricate the zone between the basket and the rotors and to prevent clogging 'Accepted' fibrous material passes through the basket laterally along flowpath 13 while rejects are caught and, after being washed by flushing water that minimizes their fibre content, are conveyed to a strainer to separate them from the water.
  • the rejects exit from the lower part of the separator along the flowpath 14.
  • the basket has a screen hole diameter between 3.5 and 6 mm dependent on the degree of cleaning required.
  • the screen hole diameter of the basket is reduced to less than 3.5 mm and preferably to around 2.5 mm in order to separate out the colloidal pollutants that it is desired to catch. Reduction of the screen hole diameter can reduce flow through the basket and, therefore, regulation of the flow by the constant level box 12 and its consistency is important Sufficient water must be provided to lubricate the zone between the basket and the rotors. This is achieved by increasing the pressure of the clarified water sprayed onto the basket from a pressure of around 1.5 bar in a conventional Separplast machine to a pressure of around 4 bar.
  • the nozzles of the sprinklers spraying this water are also increased in size from a diameter of around 1 mm to around 2 mm.
  • the diameter of the rotor is increased from around 997mm to around 999 mm. All of these changes have the effect of improving the output of the separator 11 by reducing clogging of the basket
  • the pressure of the flushing water used to wash the rejects is increased from around 2 bar in a conventional separator 11 to around 6 bar in the separator 11 of the present invention. This increased quantity of flushing water reduces to a minimum the presence of usable fibres in the rejects. All of the washing and flushing water is recovered and reintroduced into the initial pulping bath so that any usable fibres mixed with the water are reintroduced into the process and are not lost
  • the accepted flow passing along flowpath 13 can be reintroduced into the stock being processed in the main processing apparatus, preferably at an initial part of the cycle However, before reintroduction it is preferably thickened to prevent undue dilution of the stock.
  • the thickening is preferably carried out using an inclined screw thickener 15 which receives the accepted flow from the Separplast machine 11
  • Such a thickener 15 has a slow mechanical movement which drains the liquid from the fibres using gravity so that the fibres are effectively 'squeezed' together There is, therefore, a reduction in volume of the fibrous material passing through the machine as it rises through the machine from its lower inlet to an upper outlet 16.
  • Liquid draining from the stock is filtered prior to egressing from the thickener 15 via a bottom outlet 17.
  • the increase in fibre density of the accepted flow is from around 1.5% to between 4% and 5% prior to its reintroduction into the stock via a screening bath 18.
  • the liquid egressing from the outlet 17 is also reintroduced into the process at the initial pulping stage.
  • the screw thickener 15 is also modified to increase the quantity of fine usable fibres in the accepted flow that would otherwise be lost in the liquid draining from the fibrous material rising through the thickener 15.
  • These modifications involve altering the filters which are used to filter the liquid egressing from the outlet 17 so that the size of the filter holes is reduced from a diameter of 2.0 mm to a diameter of 1.25 mm.
  • the speed of rotation of the screw within the thickener 15 is reduced by approximately 20% over the speed in a conventional screw thickener of this type. This reduces the fibre content of the filtered liquid egressing from the outlet 17 from approximately 600 parts per million to around 200 parts per million.
  • the rejects in the flowpath 14 are also treated to separate them from the liquid with which they are mixed on egress from the Separplast 11. Disposal of the solid or colloidal rejects is typically by incineration or dumping and in both cases it is necessary to reduce the liquid content of the rejects so that they are around 70% dry. To this end the material in the flowpath 14 is firstly fed to a second inclined screw thickener 19. As the feed to the screw thickener 19 may be intermittent, a feeding tank (not shown) may be interposed in the flowpath 14 to feed the thickener 19 to dampen or even out the flow thereto and to supply material to the thickener 19 with a fibre density of around 2%.
  • the screw thickener 19 is adapted differently from the thickener 15 as it has to deal with larger solid waste and with the colloidal reject material.
  • the filters which are used to filter the liquid egressing from the outlet are increased in size from a diameter of 2.0 mm to a diameter of around 2.5 mm.
  • the speed of rotation of the screw within the thickener 15 is increased by approximately 15% over the speed of a conventional screw thickener of this type.
  • the compactor press 20 is provided with a large inlet hopper 22 (shown in Fig. 1 ) that is located directly beneath the outlet from the screw thickener 19. This is important because the hopper 22 must store the output from the thickener 19 whilst material already within the press 20 is compacted, the press 20 operating in a batch mode whereas the thickener 19 acts continuously.
  • material, marked A from the hopper 22 falls into compression chamber 23 wherein it is acted on by a hydraulic ram 24 and pushed upwards into an upwardly curving channel 25 at one side of the press 20
  • This action causes a first compaction of the material and the resulting released liquid, marked B , drains out of press 20 through a bottom, self-cleaning grill 26 and into a sump (not shown)
  • This liquid can then be screened and recycled back into the main pulp processing process, as indicated above
  • the inclination of the channel 25 upwards also encourages liquid held within the material in the channel 25 to drain out through the grill 26.
  • the ram 24 reciprocates within the chamber 23 with a pressure of around 21 kg/cm 2 so that on each stroke, more material A can be admitted to the chamber 23 from the hopper 22.
  • the material which is pushed upwards into the channel 25 by the ram 24 is eventually pushed upwards against a spring-loaded, top-hinged door 27 located at the top of the channel 25 as further material is pushed into the bottom of the channel 25 by the ram 24
  • the spring loading 28 applied to the door 27 is adjustable so that the degree of compaction achieved within the press 20 can be varied as required and is typically equal to a constant force of around 44,000 kg.
  • the upward pressure of material within the channel 25 overcomes the spring loading 28 and the material, marked C , is ejected through the door 27 and out of the press 20 so that it can fall into the bin 21
  • the contents of the bin 21 can then be directly disposed of by either dumping or incineration.
  • the compacted material in the bin 21 comprises plastic, pieces of wood, and the colloidal pollutants that would otherwise cause problems within the equipment of the pulp processing plant as described above.
  • the integrated cleaning arrangement of the present invention enables these pollutants to be efficiently and cost effectively removed from the process with the following consequent advantages:-

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
EP08155077A 2008-04-24 2008-04-24 Procédé et appareil pour le nettoyage intégré d'une installation de traitement de pâte à papier Withdrawn EP2112272A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP08155077A EP2112272A1 (fr) 2008-04-24 2008-04-24 Procédé et appareil pour le nettoyage intégré d'une installation de traitement de pâte à papier
US12/386,913 US20090272504A1 (en) 2008-04-24 2009-04-24 Method and apparatus for the integrated cleaning of a paper-pulp processing plant

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP08155077A EP2112272A1 (fr) 2008-04-24 2008-04-24 Procédé et appareil pour le nettoyage intégré d'une installation de traitement de pâte à papier

Publications (1)

Publication Number Publication Date
EP2112272A1 true EP2112272A1 (fr) 2009-10-28

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EP08155077A Withdrawn EP2112272A1 (fr) 2008-04-24 2008-04-24 Procédé et appareil pour le nettoyage intégré d'une installation de traitement de pâte à papier

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US (1) US20090272504A1 (fr)
EP (1) EP2112272A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2360313A1 (fr) 2010-02-22 2011-08-24 Industrial Technology & Services LLC Procédé et appareil pour le nettoyage intégré dans une installation de traitement de pâte à papier

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110904719A (zh) * 2019-11-14 2020-03-24 东莞顺裕纸业有限公司 改进碎浆的使用废纸再造瓦楞纸的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3937279C1 (en) * 1989-11-09 1991-04-18 J.M. Voith Gmbh, 7920 Heidenheim, De Multistage hydrocyclone for mfg. cellulose suspensions - has several parallel hydrocyclone cleaners which operate with specified consistency of suspension
US5622600A (en) * 1993-09-09 1997-04-22 Marcal Paper Mills, Inc. Dyed particulate or granular materials from recycled paper and process for making the materials
WO2005056914A2 (fr) * 2003-12-15 2005-06-23 Nordland Papier Gmbh Procede et dispositif de traitement d'une matiere fibreuse

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1155310B (it) * 1982-04-19 1987-01-28 Jean Marie Clement Procedimento per il trattamento di riciclaggio di carta stampata da macero

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3937279C1 (en) * 1989-11-09 1991-04-18 J.M. Voith Gmbh, 7920 Heidenheim, De Multistage hydrocyclone for mfg. cellulose suspensions - has several parallel hydrocyclone cleaners which operate with specified consistency of suspension
US5622600A (en) * 1993-09-09 1997-04-22 Marcal Paper Mills, Inc. Dyed particulate or granular materials from recycled paper and process for making the materials
WO2005056914A2 (fr) * 2003-12-15 2005-06-23 Nordland Papier Gmbh Procede et dispositif de traitement d'une matiere fibreuse

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2360313A1 (fr) 2010-02-22 2011-08-24 Industrial Technology & Services LLC Procédé et appareil pour le nettoyage intégré dans une installation de traitement de pâte à papier

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