EP0487793B1 - Procédé d'explosion pour la préparation de pâte à papier - Google Patents

Procédé d'explosion pour la préparation de pâte à papier Download PDF

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Publication number
EP0487793B1
EP0487793B1 EP19900312833 EP90312833A EP0487793B1 EP 0487793 B1 EP0487793 B1 EP 0487793B1 EP 19900312833 EP19900312833 EP 19900312833 EP 90312833 A EP90312833 A EP 90312833A EP 0487793 B1 EP0487793 B1 EP 0487793B1
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EP
European Patent Office
Prior art keywords
cooking
process according
chips
steam
pressure
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EP19900312833
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German (de)
English (en)
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EP0487793A1 (fr
Inventor
Bohuslav Vaclav Kokta
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    • 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/22—Other features of pulping processes
    • 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
    • D21B1/36—Explosive disintegration by sudden pressure reduction
    • 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
    • D21C3/022—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes in presence of S-containing compounds

Definitions

  • This invention relates to processes for the preparation of pulp for paper manufacture. More particularly, it relates to such processes which involve explosive decompression of wood fragments in the preparation of pulp.
  • S-pulping Steam Explosion Pulping Process
  • impregnation and cooking conditions were aimed at minimizing yield and brightness loss, optimizing resulting paper properties and decreasing specific refining energy.
  • the steam explosion pulping process consists of the chemical impregnation of chips, short duration saturated steam cooking at temperatures varying from about 180°C to 210°C, pressure release, refining and bleaching (if necessary).
  • the major problems accompanying previous processes using explosive decompression are believed to have been the degradation due to the oxidation of wood and acid hydrolysis leading to loss in brightness, deterioration of fibre and paper properties and loss of yield.
  • the approach adopted by this invention is therefore to attempt to curtail hydrolytic and oxidative wood degradation and thereby to protect against loss of yield, brightness and fibre strength.
  • the loss of fibre strength will be particularly great if the degree of polymerization of the cellulose falls below the critical value which is about 500-600. Hydrolytic degradation will also cause yield loss due mainly to degradation of hemi-cellulose.
  • the present invention provides a process in which additional energy saving and improved paper properties are obtained by pressurizing the reactor with inert gas before explosive decompression.
  • the process of this invention achieves a positive improvement in the strength of the paper that will be produced from the fibres by increasing the number of hydrophilic groups on the fibre surfaces thereby adding to the potential sites for hydrogen bonding.
  • the starting material will normally be chips in which the fibres are of a length suitable for paper making. Shavings could also be used but sawdust would be undesirable, except as a minor part of the total furnish, as the fibres are partially cut.
  • the chips would also, as is well known, be suitable in the sense of being free from bark and foreign matter.
  • impregnation is to protect the chips against oxidation during cooking and during transfer from the cooking vessel to the refiner. It is also an objective to provide a positive increase in strength by developing hydrophilic groups on the fibre surface during steam treatment. This will then provide additional sites for hydrogen bonding.
  • the preferred anti-oxidant is sodium sulphite, Na2SO3, which also forms hydrophilic groups, and which is available at a low cost. It is used to provide a concentration of absorbed chemical of about 1 to 15%. Concentrations below 4% would be used where brightness protection is unimportant and high strength is not required. Where, however, brightness is important the sodium sulphite should be at least 4%. If physical properties are important these will be improved by using a concentration of at least 4% sodium sulphite and will be further improved as the concentration is further increased towards 12%.
  • the concentration of the solution is preferably about the same as the percentage of chemical to be absorbed where there are equal quantities of chips and liquor.
  • EDTA ethylene diamine tetracetic acid
  • DTPA sodium diethylene triaminepentacetate
  • TPF sodium tripolyphosphate
  • complexing agents such as ethylene diamine tetracetic acid (EDTA), sodium diethylene triaminepentacetate (DTPA), sodium tripolyphosphate (TPF) and other complexing agents known in the art as being usable under alkaline conditions may be added to minimize the catalytic effect of metals such as iron on oxidative degradation.
  • a swelling agent to assist the antioxidant or hydrophilic agent in penetrating the wood and this contributes also to softening the chip.
  • Suitable swelling agents are sodium or potassium hydroxide or ammonium hydroxide or sodium carbonate or sodium bicarbonate which will contribute also to providing hydrophilic groups.
  • Other swelling agents that can be used and which may be desirable as auxiliary swelling agents for high density wood are zinc chloride, sodium chloride, sodium bromide, calcium isocyanate, Schweitzers solution, cupriethylenediamine (C.E.D.) tetraethylammonium hydroxide and dimethyldibenzylammonium hydroxide.
  • the concentration of swelling agent and conditions of swelling must be controlled in such a way as to avoid any dissolution of the hollocellulose.
  • the percentage of swelling agent in the impregnating solution will be in the range of about 1 to 4% depending on the agent and the conditions.
  • the impregnating solution must be alkaline and have enough free hydroxyl to be able to neutralize the liberated wood acids such as formic acid and acetic acid. Normally the starting pH is about 7.5 or higher and the final pH after steam cooking should be at least 6 or higher.
  • the time of impregnation at atmospheric pressure in holding tanks typically ranges from about 12 hours to 24 hours at a temperature of about 30°C to 60°C. Approximately equal weights of chips and of aqueous impregnating solution can be used. For industrial purposes, however, the time may be shortened to an hour or to minutes by impregnating with steam under pressure and at a higher temperature.
  • the pressure should be up to about 100kPa (1 atmosphere) extra pressure at a temperature of about 100°C to 110°C.
  • the impregnation may be carried out in the substantial absence of air, achieved by replacing air with saturated steam.
  • the chips should be compressed in advance of impregnation in solutions of the chemicals, sodium sulphite, or sodium sulphite and swelling agent and complexing agent DTPA etc., at a temperature of about 15-50°C. Under these conditions, penetration will be achieved in a shorter time, but penetration is what predominantly occurs. There is no significant cooking.
  • the impregnated chips are steam cooked at a high temperature and pressure.
  • the temperature of cooking should be within the range of about 180°C to 210°C and preferably within the range 190-200°C. These temperatures correspond with a pressure of about 1.0 MPa (10 atmospheres) for 180°C and about 1.57 MPa (15.5 atmospheres) for 200°C. It is these high pressures which make a very important contribution to ensuring excellent penetration of the chips by the cooking liquor.
  • the cooking may be preceded by steam flushing under low pressure steam at 100°C for a short period such as one minute.
  • steam flushing under low pressure steam at 100°C for a short period such as one minute.
  • This preliminary treatment is then followed by cooking for about 30 seconds to 6 minutes and preferably about 1 to 4 minutes.
  • the reactor After cooking, the reactor is pressurized immediately with an inert gas such as nitrogen.
  • an inert gas such as nitrogen.
  • the pressurisation conducted after cooking with saturated steam is accomplished in order to obtain optimum results as far as paper properties, yield and brightness are concerned.
  • the nitrogen temperature being well below the cooking temperature, is not likely to increase hydrolysis and decrease cooking yield.
  • the use of nitrogen pressure varying from about 2.5 MPa to 5.0 MPa (25 to 50 atm), contributes to even more efficient chip defibration in the subsequent step of pressure release.
  • the chips resulting from the explosive decompression are softened and partially defibrated.
  • Refining energies are usually low and can be expected to be in the range of 2.6 to 4 MJ/kg, hardwoods, CSF ⁇ 100 ml, which is considerably lower than that of conventional CMP and about 20% lower than that described in Kokta, CA-A-1 230 208 and US-A-4 798 651 (1989).
  • Explosion pulps have been prepared using vapor phase steam cooking of sulfite pretreated aspen wood chips. Pulps have been prepared with the same 90% yield by using cooking temperatures 190°C, 195°C and 200°C with cooking times 2 minutes, 1.5 minute and 1 minute respectively.
  • Cooking took place using saturated steam in a laboratory batch reactor built by Stake Tech. Co. Cooking was preceded by one minute steam flushing at atmospheric pressure. After cooking, the pressure was instantaneously released and chips which exploded into the release vessel were washed and cooled down with one litre of tap water, and subsequently refined after being stored in a cold room. The reported amount of steam used for cooking varied from 0.5 to 1 kg of steam for 1 kg of chips. Yield was measured as follows: exploded chips (75 g) were washed with one litre of tap water and subsequently defibrated for 90 seconds in a laboratory blender at 2% consistency. The pulp was washed again with one litre of water, dried at 105°C to constant weight and the resulting weights were compared with the initial weight of chips.
  • Paper sheets were prepared and tested according to standard CPPA testing methods on 1.2 g sheets. Brightness (Elrepho) was evaluated on sheets made with deionized water.
  • Bleaching was carried out using 4% of hydrogen peroxide.
  • the yield of nitrogen exploded pulps has not been decreased by more than 0.4% compared to ordinary exploded pulps.
  • the nitrogen explosion process seems to be very promising in the field of explosion pulping processes. It allows the preparation of very high yield pulps which are easy to refine; they can be easily bleached to more than 80% MgO brightness by single stage peroxide bleaching and their properties are superior to conventional CMP/CTMP with the same yield.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Paper (AREA)

Claims (10)

  1. Procédé pour produire de la pâte, comprenant :
    l'imprégnation de fragments de bois avec une solution capable de fournir des groupes hydrophiles et un antioxydant dans les fragments,
    la cuisson à la vapeur des fragments imprégnés dans un réacteur avec de la vapeur saturée à une pression superatmosphérique et à une température dans l'intervalle de 180° à 210°C,
    la décompression de façon explosive des fragments cuits, et
    le raffinage subséquent du produit pour fournir la pâte, caractérisé en ce qu'après la cuisson à la vapeur, le réacteur est de plus mis sous pression avec un gaz inerte à une température de 10 à 50°C avant ladite décompression explosive.
  2. Procédé selon la revendication 1 dans lequel le gaz inerte est l'azote.
  3. Procédé selon la revendication 2 dans lequel la pression d'azote est de 2,5 à 5,0 MPa (25 à 50 atmosphères).
  4. Procédé selon l'une quelconque des revendications 1 à 3 dans lequel l'étape d'imprégnation des fragments de bois est mise en oeuvre en l'absence substantielle d'air, atteinte en remplaçant l'air par de la vapeur saturée.
  5. Procédé selon l'une quelconque des revendications 1 à 4 dans lequel la solution utilisée pour imprégner les fragments de bois contient du sulfite de sodium.
  6. Procédé selon l'une quelconque des revendications 1 à 5 dans lequel la cuisson à la vapeur est effectuée à une température de 190°C à 200°C.
  7. Procédé selon l'une quelconque des revendications 1 à 6 dans lequel la cuisson à la vapeur est effectuée à une pression de 1,0 à 1,57 MPa (10 atmosphères à 15,5 atmosphères).
  8. Procédé selon l'une quelconque des revendications 1 à 7 dans lequel la cuisson à la vapeur est effectuée pendant une durée de 30 secondes à 6 minutes.
  9. Procédé selon l'une quelconque des revendications 1 à 8 dans lequel la mise sous pression supplémentaire est effectuée pendant une durée de 5 secondes à 2 minutes.
  10. Procédé selon l'une quelconque des revendications précédentes dans lequel la solution utilisée pour imprégner les fragments de bois contient du carbonate de sodium ou du bicarbonate de sodium.
EP19900312833 1990-11-26 1990-11-26 Procédé d'explosion pour la préparation de pâte à papier Expired - Lifetime EP0487793B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19900312833 EP0487793B1 (fr) 1990-11-26 1990-11-26 Procédé d'explosion pour la préparation de pâte à papier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19900312833 EP0487793B1 (fr) 1990-11-26 1990-11-26 Procédé d'explosion pour la préparation de pâte à papier

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EP0487793A1 EP0487793A1 (fr) 1992-06-03
EP0487793B1 true EP0487793B1 (fr) 1995-08-30

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EP19900312833 Expired - Lifetime EP0487793B1 (fr) 1990-11-26 1990-11-26 Procédé d'explosion pour la préparation de pâte à papier

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Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2037275A1 (fr) * 1991-02-28 1992-08-29 Bohuslav V. Kokta Procede de fabrication de pate a papier par cuisson a la vapeur suivie de detente explosive de celle-ci
US6413362B1 (en) 1999-11-24 2002-07-02 Kimberly-Clark Worldwide, Inc. Method of steam treating low yield papermaking fibers to produce a permanent curl
KR20010100017A (ko) 1998-12-30 2001-11-09 로날드 디. 맥크레이 화학물질을 첨가하는 증기 폭발 처리
WO2002081816A1 (fr) * 2001-04-06 2002-10-17 Gerischer Guenter Friedrich Ru Traitement de copeaux de bois
CA2638152C (fr) 2008-07-24 2013-07-16 Sunopta Bioprocess Inc. Methode et appareil permettant le traitement d'une charge d'alimentation cellulosique
CA2638157C (fr) 2008-07-24 2013-05-28 Sunopta Bioprocess Inc. Methode et appareil permettant le transport d'une charge d'alimentation cellulosique
CA2638150C (fr) 2008-07-24 2012-03-27 Sunopta Bioprocess Inc. Methode et appareil permettant le transport d'une charge d'alimentation cellulosique
CA2638159C (fr) 2008-07-24 2012-09-11 Sunopta Bioprocess Inc. Methode et appareil permettant le traitement d'une charge d'alimentation cellulosique
CA2638160C (fr) 2008-07-24 2015-02-17 Sunopta Bioprocess Inc. Methode et appareil permettant le transport d'une charge d'alimentation cellulosique
CA2650913C (fr) 2009-01-23 2013-10-15 Sunopta Bioprocess Inc. Methode et appareillage de transport de produits de depart cellulosiques
US8915644B2 (en) 2008-07-24 2014-12-23 Abengoa Bioenergy New Technologies, Llc. Method and apparatus for conveying a cellulosic feedstock
US9127325B2 (en) 2008-07-24 2015-09-08 Abengoa Bioenergy New Technologies, Llc. Method and apparatus for treating a cellulosic feedstock
CA2650919C (fr) 2009-01-23 2014-04-22 Sunopta Bioprocess Inc. Methode et installation de transport de produit de depart cellulosique
PL2467532T3 (pl) 2009-08-24 2014-11-28 Abengoa Bioenergy New Tech Llc Sposób wytwarzania etanolu i współproduktów z biomasy celulozowej
CN103362008A (zh) * 2012-04-01 2013-10-23 中国科学院过程工程研究所 一种以碱木质素为胶粘剂的汽爆秸秆生态板制备方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE434652B (sv) * 1977-04-27 1984-08-06 Commw Scient Ind Res Org Forfarande for explosionsdefibrering av cellulosafibrer fran vextmaterial samt utmatningsmunstycke for genomforande av forfarandet
CA1230208A (fr) * 1987-03-24 1987-12-15 Bohuslav V. Kokta Preparation de la pate a papier

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EP0487793A1 (fr) 1992-06-03

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