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EP1540073A1 - Procede de fabrication d'une pate mecanique ou chimico-mecanique et appareil associe - Google Patents

Procede de fabrication d'une pate mecanique ou chimico-mecanique et appareil associe

Info

Publication number
EP1540073A1
EP1540073A1 EP03761888A EP03761888A EP1540073A1 EP 1540073 A1 EP1540073 A1 EP 1540073A1 EP 03761888 A EP03761888 A EP 03761888A EP 03761888 A EP03761888 A EP 03761888A EP 1540073 A1 EP1540073 A1 EP 1540073A1
Authority
EP
European Patent Office
Prior art keywords
reject
refining
wood material
accept
defibrated
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Withdrawn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
EP03761888A
Other languages
German (de)
English (en)
Inventor
Börje SVENSSON
Lars-Ake Hammar
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.)
STFI Skogsindustrins Tekniska Forskningsinstitut AB
Original Assignee
STFI Skogsindustrins Tekniska Forskningsinstitut 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 STFI Skogsindustrins Tekniska Forskningsinstitut AB filed Critical STFI Skogsindustrins Tekniska Forskningsinstitut AB
Publication of EP1540073A1 publication Critical patent/EP1540073A1/fr
Withdrawn legal-status Critical Current

Links

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

Definitions

  • the invention relates to a method of manufacturing mechanical and chemi- mechanical pulp by disintegrating and treating wood material.
  • the invention also relates to an apparatus for manufacturing mechanical or chemi-mechanical pulp.
  • One object of the invention is to carry out the disintegration and refining of the pulp in such a manner, that the total energy consumption is substantially reduced, as will be described in the following.
  • thermo-mechanical pulp is conventionally manufactured with high consistency- technology (HC-technology).
  • TMP thermo-mechanical pulp
  • the refining process is often divided into two HC-refining steps with a total energy consumption of about 2000-2500 kWh/ton including reject refining.
  • As a rule 2/3 (1200-1700 kWh/ton) of the energy is consumed in the primary step and 1/3 (600-800 kWh/ton) in the secondary step.
  • US 6267841 Bl discloses a pulping process where the wood material after a primary refining step is treated with enzymes and is further treated in a secondary refining step. By using enzymes it is possible to use low-energy refining in both refining steps.
  • WO 8906717 Al discloses a method of making mechanical pulp. After a high- energy refining step of approximately 2000 kWh/ton the pulp is screened and the reject is further refined in two steps before its reunited with the rest of the pulp. During this process chemicals are added at different stages to further grind and improve the pulp quality.
  • a conventional process for making pulp for newspaper use comprises high- energy refining steps approximately using 2000-2500 kWh/t. This is to improve pulp properties and make sure that the shives are reduced to a satisfactory content. This is a high energy consumption and it is an object of this invention to substantially reduce it.
  • This invention relates to a new method and a new apparatus for removing the problems and drawbacks with known techniques according to the objects of the invention mentioned above.
  • the new method is characterized by the following steps:
  • wood material is defibrated in a first step with a low energy input and then
  • reject is screened from the accept (main part of the defibrated wood material) and then
  • a preferred embodiment of the method is further characterized by that the accept is refined after the screening.
  • Another preferred embodiment of the method is further characterized by that the refining of the accept is performed in a low consistency (LC) refining process.
  • LC low consistency
  • Another preferred embodiment of the method is further characterized by that the first step defibration is performed at a high rotation speed.
  • Another preferred embodiment of the method is further characterized by that the reject is refined in a high consistency process.
  • Another preferred embodiment of the method is further characterized by that the reject after refining is screened and possible remaining reject is fed back for further refining.
  • Another preferred embodiment of the method is further characterized by that the reject is mixed with the accept before this second screening step.
  • the new apparatus is characterized by a defibration device with a low energy input defibrating the wood material, a screening device separating reject from the accept, a reject refining device and a mixing stage, mixing the refined reject with the accept.
  • a preferred embodiment of the apparatus is further characterized by that it comprises a refiner stage refining the accept.
  • Another preferred embodiment of the apparatus is further characterized by that the accept refiner is refining at low consistency, 2-6%.
  • Another preferred embodiment of the apparatus is further characterized by that the reject refiner is refining at low consistency.
  • Another preferred embodiment of the apparatus is further characterized by that it after the reject refiner comprises, devices for screening the reject and feeding possible remaining reject back to the reject refiner.
  • Figure 1 discloses a schematic view of the steps of the process according to the invention.
  • Figure 2 discloses a diagram showing tensile strength as a function of energy input per ton.
  • Fig. 1 a first embodiment of the process of the invention. A first
  • Step 1 of the process comprises a defibration step, preferably at a high speed (approximately 1500 rpm or higher), defibrating the wood material.
  • Defibration at high speed has proven to be very effective in reducing the amount of shives in the defibrated material.
  • This first defibration step is using a very low energy input of 400-900 kWh/t at high consistency as it has been shown that 65-95% of the wood material is aheady defibrated to fibers at this low energy input.
  • An alternative to high speed defibration is to use double-disc refiners. Two discs are then rotating in opposite directions. The rotating speed can then be kept lower with the same effect because of the relative movement of the discs.
  • Another conventional way of lowering the energy input is to increase the grinding gap.
  • a common practice to use a higher energy input in the defibration (primary refiner) with the purpose to decrease the shive content gives the result that already defibrated fibers are only to a small degree further treated. Most of this extra higher energy input is namely mostly consumed by decreasing residual content of shives. Because of the high content of already defibrated fibers achieved already at a very low energy input, further energy input in the the primary refiner does not lead to treatment of the defibrated fibers. The shives are bigger in size compared to the smaller size of defibrated fibers. Therefore, further energy input is consumed for the defibration of shives.
  • Step 2 of the process is a screening step where the shives are screened from the coarse defibrated pulp and thus become reject.
  • This screening can be performed in two steps to make sure that the capacity is sufficient to screen all the coarse defibrated pulp from shives.
  • the screening is performed after two steps of refining when the pulp contains only a few percent shives and after a substantial energy consumption.
  • the shives (reject) and the accept are treated separately. To treat the accept and reject separately makes it possible to adapt the treatment for the respective type and this results in a more energy effective process.
  • the accept is after Step 2 treated in a low consistency refiner 3.
  • the low consistency refining is preferably performed at an energy effort of about 200-400 kWh/ton at 85-95°C and at a pulp concentration of 2-6%.
  • the increased LC-refining temperature is due to more softening of the lignin. Because of the technology in low consistency refining with a smaller plate gap makes the process intensive and energy effective. This results in an intensive and very effective processing of the pulp.
  • a reliable measure of the low energy exploitation in conventional processes compared to the process of the present invention is the tensile index as a function of the energy input per ton.
  • the diagram in Fig. 2 shows in curve 1 (LEMP) how the tensile index of the process of the present invention shows a more or less linear character and therefore shows a favourable development of the tensile strength against energy consumption while curve 2 (Reference) representing the conventional processes very soon deviate from the linear curve due to akeady refined fibers remaining with the shives causing an excessive amount of energy to be needed to reach the same tensile strength.
  • the reject (shives) from Step 2 is processed in either a conventional HC-reject refiner 4 or a LC-refmer. It is preferred that this process takes place in a pressurized environment, e.g. 15-20% more than the atmospheric pressure. This is to achieve a more lenient processing due to softening of the lignin. It is further preferred if the reject pulp is screened again in a screening device 5 with a feed-back of possible remaining shives to the reject refining step. A hydrocyclone may be used to further separate remaining shives from the pulp. LC-processed accept and the reject are finally mixed at the end of the process 6. The different characteristics of the reject and accept can then by changing ingoing proportions be used to obtain pulps with desired properties blended into a desired mix.
  • the accept is after the LC-refining, led to the reject just after the reject refining 4 but before the screening 5.
  • the advantage of this alternative process is that an extra safety feature is added in that the accept will be screened once more together with the reject and the process is thus taking care of eventual deficiencies in earlier screening 2 and refining steps 3.
  • the total energy consumption of the process according to this invention can in an industrial application be 1000-1400 kWh/ton or even lower. With a conventional process the energy consumption varies from 2000 to 2500 kWh/ton. It is thus possible to reduce the energy consumption to 50% with the process according to this invention.

Landscapes

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

Abstract

La présente invention concerne un procédé qui permet de fabriquer une pâte mécanique ou chimico-mécanique par désintégration et traitement du bois. Dans une première étape, le bois est défibré avec un faible apport d'énergie par rapport aux processus traditionnels. Ensuite on trie le rebut du bois défibré. On raffine alors le rebut séparément et on le mélange à nouveau avec le reste du bois défibré afin d'obtenir un produit de pâte final. L'invention se rapporte également à un appareil qui permet de fabriquer une pâte mécanique ou chimico-mécanique par désintégration et traitement d'une matière à base de bois. L'appareil comprend un dispositif de défibrage (1) à faible apport d'énergie, un dispositif de tri (2) qui sépare le rebut de la partie principale du bois défibré, un dispositif de raffinage de rebut (4) et un dispositif (6) qui mélange le rebut raffiné avec le reste de la matière à base de bois. Un objet de l'invention est de permettre la désintégration et le raffinage de la pâte d'une manière telle que la consommation d'énergie totale est sensiblement réduite par rapport aux procédés traditionnels. Un autre objet de l'invention est d'offrir un procédé et un appareil qui permettent de maîtriser facilement, par le choix des apports d'énergie, les caractéristiques du produit final en régulant les propriétés du bois défibré tout au long du processus.
EP03761888A 2002-07-01 2003-07-01 Procede de fabrication d'une pate mecanique ou chimico-mecanique et appareil associe Withdrawn EP1540073A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE0202032A SE0202032D0 (sv) 2002-07-01 2002-07-01 Metod för tillverkning av mekanisk eller kemi-mekanisk massa och en anordning för tillverkning av densamma
SE0202032 2002-07-01
PCT/SE2003/001146 WO2004003288A1 (fr) 2002-07-01 2003-07-01 Procede de fabrication d'une pate mecanique ou chimico-mecanique et appareil associe

Publications (1)

Publication Number Publication Date
EP1540073A1 true EP1540073A1 (fr) 2005-06-15

Family

ID=20288382

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03761888A Withdrawn EP1540073A1 (fr) 2002-07-01 2003-07-01 Procede de fabrication d'une pate mecanique ou chimico-mecanique et appareil associe

Country Status (5)

Country Link
EP (1) EP1540073A1 (fr)
AU (1) AU2003243114A1 (fr)
CA (1) CA2491533A1 (fr)
SE (1) SE0202032D0 (fr)
WO (1) WO2004003288A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI121311B (fi) 2005-05-03 2010-09-30 M Real Oyj Menetelmä paperin- ja kartonginvalmistukseen soveltuvan mekaanisen massan valmistamiseksi
DE102007036379A1 (de) * 2007-07-31 2009-02-05 Voith Patent Gmbh Verfahren zum Herstellen von Feinstoff aus Faserstoff-Rejekts
CA2824076A1 (fr) 2012-08-21 2014-02-21 University Of New Brunswick Systeme et procede de recuperation des rejets dans le procede de fabrication de pate au bisulfite

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE459924B (sv) * 1988-01-22 1989-08-21 Sunds Defibrator Saett foer framstaellning av mekanisk massa
SE513140C2 (sv) * 1998-11-19 2000-07-10 Valmet Fibertech Ab Förfarande för framställning av uppgraderad tidningspappersmassa till SC/LWC kvalitet

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2004003288A1 *

Also Published As

Publication number Publication date
WO2004003288A1 (fr) 2004-01-08
CA2491533A1 (fr) 2004-01-08
SE0202032D0 (sv) 2002-07-01
AU2003243114A1 (en) 2004-01-19

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