EP3215672B1 - Procédé de fonctionnement d'un système de digesteur à deux cuves - Google Patents

Procédé de fonctionnement d'un système de digesteur à deux cuves Download PDF

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Publication number
EP3215672B1
EP3215672B1 EP15857624.9A EP15857624A EP3215672B1 EP 3215672 B1 EP3215672 B1 EP 3215672B1 EP 15857624 A EP15857624 A EP 15857624A EP 3215672 B1 EP3215672 B1 EP 3215672B1
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EP
European Patent Office
Prior art keywords
liquor
digester
cooking
vessel
impregnation
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German (de)
English (en)
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EP3215672A1 (fr
EP3215672A4 (fr
Inventor
Fredrik Wilgotson
Magnus Hägglund
Krister Olsson
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Valmet Technologies Oy
Valmet AB
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Valmet Oy
Valmet AB
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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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • 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
    • 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
    • D21C3/24—Continuous processes
    • 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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/0021—Introduction of various effluents, e.g. waste waters, into the pulping, recovery and regeneration cycle (closed-cycle)
    • D21C11/0028—Effluents derived from the washing or bleaching plants
    • 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
    • D21C7/00—Digesters
    • D21C7/14—Means for circulating the lye
    • 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
    • D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents

Definitions

  • the present invention concerns a method for the continuous cooking of cellulose according to the introduction to claim 1 with the aim of achieving improved washing and delignification at less losses in heat economy.
  • Compact CookingTM was the two vessel digester system further improved with the main objectives to increase yield and uniform cooking results.
  • Most dominant features in Compact Cooking was impregnation as well as cooking at high L/W ratios, enabling presence of high amount of alkali in kg per kg of wood, while reducing the concentrations of alkali, and less cooking circulations that often established an uneven alkali distribution over the cross section. This uneven alkali distribution was seen in the larger digesters developed at this time with capacities over 4000 ton pulp per day and with a digester diameter in excess of 6 meter or more.
  • Compact Cooking is more of an opposite to Lo-Solids cooking as the content of dissolved hemicellulose is kept high during the cook in order to increase yield as the hemicellulose starts to precipitate back on the pulp at final phases of cook.
  • Hemicelluose is a large part of the dissolved organic content, which in Lo-Solids cooking deliberately is kept low throughout the cook by multiple extractions of black liquor, and often the total organic content is kept below 100 g/l throughout the cook, which of course results in losses in yield.
  • ImpBin developed with CrossCirc TM .
  • This combination of an atmospheric impregnation vessel with substantial retention time, and a dedicated cooking vessel is the optimal design of the digester system.
  • the atmospheric impregnation vessel enable a thorough impregnation of comminuted cellulosic material with alkali all the way to the core of the comminuted cellulosic material, reducing the amount of rejects after cook to a minimum.
  • the comminuted cellulosic material are also steamed in the very same vessel by adding hot black liquor to the liquor level established in the ImpBin, allowing steam to flash off and into an established chip volume above liquor level.
  • the patent US7112256 is related to the CrossCirc features that the bulk volume of return liquor from the top separator is instead sent to this liquor level in ImpBin, and before that is instead hot black liquor added to start of transfer (instead of the top separator return liquor that was conventional practice). This improves heat economy as heating takes place towards cooking temperature in transfer to digester, and the residual heat in the top separator return liquor is allowed to flash off for steaming, while yet establishing a low impregnation temperature in black liquor after flashing.
  • FIG. 2 A more detailed process flow chart of a Compact Cooking G2, using an ImpBin and CrossCirc is shown in figure 2 .
  • the digester is simplified with only 2 screen sections, and in the first upper screen section is hot black liquor HBL 1 withdrawn at full cooking temperature. This HBL 1 is added to end of ImpBin and at start of transfer of the comminuted cellulosic material to raise the temperature in feed line TS FEED to top separator according to CrossCirc practice.
  • steaming comminuted cellulosic material being fed at ambient temperature directly to ImpBin requires quite different amount of steam if the comminuted cellulosic material are fed from an outside chip pile at ambient temperatures of -30 to -40°C, compared to feeding comminuted cellulosic material from an outside chip pile at ambient temperatures of +30 to +40°C.
  • the further heating is only done in cold seasons while no further heating is done in warm seasons.
  • the heating effect of the hot black liquor is first used to elevate the temperature in transfer towards cooking temperature without any heat losses, and the residual heat value in the liquor withdrawn in top separator is used to produce the necessary amount of steaming of the comminuted cellulosic material in ImpBin.
  • spent cooking liquor is withdrawn from end of digester, REC 2 , and preferably also from a withdrawal at liquor level in ImpBin, i.e. REC 1 , and sent further to evaporation plant ahead of final recovery in a recovery boiler.
  • FIG. 3 An essential feature of the atmospheric ImpBin system is shown in more detail in figure 3 .
  • the temperature profile established in the chip volume above liquor level, and above release point of the return liquor TS RET develop a hot zone (>100°C) where steaming of comminuted cellulosic material is obtained.
  • a transition zone is a cold buffer zone established at ambient temperature, i.e. the temperature which the comminuted cellulosic material has on entry to the ImpBin.
  • steam and condensable gases accumulates in condensate layers inside the chip volume and is prevented from escaping by the colder comminuted cellulosic material laying above the transition zone. Only air and some non-condensable gases passes through the cold chip volume and is vented off by a DNCG (Diluted Non Condensable Gas) system (as shown in figure 2 ).
  • DNCG Diluted Non Condensable Gas
  • ImpBin As colder comminuted cellulosic material are continuously fed into the ImpBin is this transition zone balanced with the amount of steam released in the chip volume, and the control of steam release is controlled by a temperature probe penetrating the chip volume (not shown). If the transition zone moves downwardly more return liquor TS RET is added or additional heating thereof, or alternatively using low pressure steam as a complementary steaming effect.
  • FIG. 4 shows in further detail the liquor routing in Compact Cooking G2.
  • the digester is operated with only 2 concurrent cooking zones, charging the white liquor WL to top of digester where it mixes well with the inflow of impregnated comminuted cellulosic material.
  • a L/W ratio of about 5 is established in first cooking zone and after this zone is hot partially spent cooking liquor, i.e. black liquor, withdrawn in a L/W ratio of about 3.
  • This hot black liquor is charged to start of transfer as shown in order to raise the temperature in the transport circulation where a L/W ratio of about 10-12 is established.
  • the top separator In the top separator is excess transport liquor withdrawn at a L/W ratio of about 6-8, and this transport liquor is sent to top of ImpBin to be released into the chip pile volume established above the liquor level, where steam is released.
  • the impregnation liquor for the ImpBin is established by the hot black liquor withdrawal which after mixing into the transport circulation for heating, is withdrawn in top separator and sent to top of ImpBin.
  • the black liquor is thus given an increased retention time in the cooking system as it is recirculated back to ImpBin and maintained in first cooking zone.
  • the increased retention time is beneficial for increasing yield, as the hemicellulose dissolved early in cooking need time and high alkali concentration for cleaving off end groups to such an extent that it precipitates back on the cellulose.
  • the effect of hemicellulose precipitation is dependent on the H-factor exposure of the dissolved hemicellulose.
  • the temperature established in the liquor level is about 100-102°C and the only heating subjected to the comminuted cellulosic material during impregnation is the heat release due to exothermic reactions, reaching about 110°C in bottom. This low temperature results in a minimal H-factor and neglectable alkali consumption due to delignification reactions.
  • the invention is all about a further improvement of the Compact Cooking G2 concept, where increased yield is one of the major objectives for the cooking concept.
  • the ImpBin concept used in Compact Cooking G2 is beneficial for recovery of heat value in cooking liquors and thus reducing heating costs, i.e. need for fresh steam.
  • total yield is high in a Compact Cooking G2 process, it has shown that the order of delignification in last phase of cooking is low, typically is the kappa number reduction in last half of cooking zone in the order of 15-20, while the kappa number reduction in first half is in the order of 60-100..
  • the carry over of COD in the digester blowline is in the range of 500-700 kg/adt.
  • the invention is an improvement of a method for cooking comminuted cellulosic material in which method is used a two vessel continuous digester system comprising a first atmospheric impregnation vessel and a second pressurized digester vessel, wherein the cellulosic material has a retention time of at least 40 minutes in the first impregnation vessel and at least 90 minutes in the second digester vessel, and where a liquor level of at least 15 meter is established in the first impregnation vessel, said method comprising following steps in sequence;
  • the invention is characterized in that in this context is an additional volume of at least 0.5 ton liquor/bdt wood of wash filtrate from a subsequent brown wash position after the digester added to the center of the digester vessel at the digester withdrawal screen after heating the wash filtrate to full digester temperature, said wash filtrate having a lignin content less than 50% of the lignin content in the black liquor withdrawn in the withdrawal screen, and finally withdrawing a corresponding amount of liquor as additional liquor also from the withdrawal screen in the impregnation vessel thus using the heat value of the heated wash filtrate first in transfer circulation and subsequently as hot impregnation liquor releasing more steam for chip steaming.
  • a further embodiment of the inventive method is fresh alkaline liquor charged to the two vessel digester system in a total charge of 160-190 (HW) and 190-230 (SW) kg alkali/bdt wood (EA as NaOH) in at least 3 process positions, wherein a first charge is added to the top of the digester in an amount exceeding 60% of the total charge of fresh alkaline liquor, and a second charge to the hot impregnation liquor and a third charge to the wash filtrate added to the center of the digester vessel at the digester withdrawal screen.
  • HW 160-190
  • SW 190-230
  • EA alkali/bdt wood
  • the inventive method is the amount of fresh alkaline liquor charged to the wash filtrate charged to a cooking circulation recirculating a part of the liquor withdrawn from the digester withdrawal screen to the center of the digester vessel. This enforced circulation could improve radial distribution of the modified cooking liquor ahead of the final cooking zone.
  • the inventive is also the amount of fresh alkaline liquor charged to the hot impregnation liquor corresponding to at least 10% of the total charge of fresh alkaline liquor, wherein the charge is sufficient to establish a final residual alkali level in the impregnation vessel over 8 g/l (as NaOH), and preferably above 15 g/l.
  • a charge control could guarantee that sufficient amount of alkali is present during the entire impregnation, safeguarding that the alkali diffusion into the comminuted cellulosic material continues during the entire residence time in the impregnation vessel.
  • the wash filtrate from a subsequent brown wash position after the digester obtained from a pressurized wash, maintaining the pressure of the wash filtrate before addition to digester. If the wash filtrate is kept pressurized the temperature may be equal to or exceed the corresponding amount of spent impregnation liquid that is withdrawn from the impregnation vessel, improving heat economy of the two vessel system.
  • the wash filtrate from a subsequent brown wash position after the digester obtained from a pressurized wash maintaining the temperature of the wash filtrate before addition to digester above 100°C, and preferably in the range 100-110°C.
  • the wash filtrate could preferably be obtained from a subsequent brown wash position immediately after the digester, preferably in a pressure diffuser.
  • the wash filtrate from a subsequent brown wash position after the digester may alternatively be obtained from a wash after an oxygen delignification stage, maintaining the temperature of the wash filtrate before heating and addition to digester in the range 85-95°C or above.
  • Such a high temperature wash filtrate may still be beneficial for reducing the heat losses, as the temperature loss is only 5-15°C higher temperature in liquor withdrawn from the impregnation vessel than the wash filtrate added to digester.
  • liquor-to-wood / L/W ratio used, meaning the total amount of liquid in ton per ton of bone dry wood (bdt).
  • the example use a minimum charge of an additional volume of wash liquor of at least 0.5 in L/W, in order to indicate the minimum order of liquor charged.
  • the invention may be applied with increasing volumes up to a L/W ratio up to 2, or even more of the added liquor volume charged as wash liquor and then passed on through the system via first transport circulation and finally to impregnation vessel.
  • This cleaner wash liquor WL is heated in a heat exchanger HE to full cooking temperature before addition.
  • the wash liquor is preferably a wash liquor from a subsequent brown wash position, either from a wash directly after the digester or a wash after pre-bleaching or oxygen delignification, where the wash liquor still is alkaline.
  • the temperature of the wash liquor from a brown wash position is typically in the order of 90-110°C, and in the lower range if the washing is done in wash machines collecting the wash filtrate in atmospheric filtrate tanks, and in the upper range if the washing is done in wash machines keeping the wash filtrate pressurized.
  • the COD content in such brown wash positions is typically in the order of 30-80 g/l filtrate, which could be compared with the COD content of the mid screen withdrawal in digester which typically may be about 200 g/l, and thus higher COD content at end of cooking zone and before the bottom wash.
  • a corresponding additional amount of black liquor i.e. in a L/W ratio of at least 0.5, is withdrawn from the withdrawal screen and sent to start of transfer.
  • This additional amount of hot black liquor will elevate the temperature in the transport circulation, as the part of the hot black liquor in the transport liquor increases.
  • the excess transport liquor withdrawn from top separator but now at an increased volume in a L/W ratio of at least 0.5 of the increase.
  • ImpBin withdrawal screen is also the withdrawal volume increased at an increased volume in a L/W ratio of at least 0.5. This modification leaves the cooking process otherwise unaffected as to liqour-to-wood ratios during impregnation or cooking, maintaining the advantages of the Compact Cooking G2 process.
  • a cooking circulation CC be installed, that promotes an enhanced radial distribution of the new cooking liquor.
  • a cooking circulation normally includes also a pump (not shown).
  • the amount of fresh alkaline liquor charged to the wash filtrate is charged to a cooking circulation recirculating a part of the liquor withdrawn from the digester withdrawal screen to the center of the digester vessel at the height position of the digester withdrawal screen (as shown in figure 5 ), or alternatively is charged to a cooking circulation recirculating a part of the liquor withdrawn from a wash withdrawal screen (the lowermost screen shown in figure 5 ) to the center of the digester vessel at the height position of the digester withdrawal screen.
  • ImpBin the extra amount of steam flashed off in the ImpBin will reduce the need for adding extra steam, i.e. LP-steam, to top of ImpBin.
  • This reduction of steam addition match the need for heating the wash liquor in heater HE, so in aspects of heat economy the change is not increasing steam consumption.
  • ImpBin screen In the boundary limits of the two vessel system is an additional volume of wash liquor added to the digester and the corresponding amount of recovery withdrawal increase is done from ImpBin screen. If these volumes are identical and the temperature in the ImpBin withdrawal is about 100°C, then no increased cost of steam is caused in the two vessel digester system if the wash liquor has the same temperature, i.e. 100°C, before heating. For each degree of temperature increase in wash liquor is the steam economy improved as less fresh steam (LP steam) needs to be added to ImpBin top as a result or if the steam to the ImpBin is enough the hot black liquor will be used to increase the temperature of the transfer circulation and the MP-steam demand on the digester top to reach cooking temperature will reduce.
  • LP steam fresh steam
  • the COD content in mid-point withdrawal at some 200 g/l. If no dilution of the cooking liquor and addition of alkali is made at this position the COD content will increase further during the final cooking zone.
  • the first phase of the cook is performed with high level of dissolved organic content, primarily hemicellulose and lignin in almost equal proportions, but then the final phase is modified slightly, decreasing the concentration of lignin and optionally increasing the alkali concentration for the final phase of the cook.
  • This modification of the cooking liquor improves delignification, such the typical low order of delignification that could be obtained in final delignification, reaching a kappa reduction in the order of 15-20 units, may be increased by at least 5-10 units.
  • the COD level in pulp typically about 900 kg per bdt pulp (not wood), while after a modification of the cooking liquor the COD level may be reduced to below 650 kg. This improves bleachability, as less bleaching chemicals are needed to reach the desired brightness.
  • FIG 6 a preferred brown wash in form of a pressure diffuser washing the pulp coming directly from the blow line of the digester.
  • This system installation follow the DiConn TM concept sold by Valmet, where the filtrate obtained from the pressured diffuser is kept pressurized making it possible to maintain the temperature of the wash filtrate above 100°C.
  • the wash filtrate from the pressure diffuser collected in an atmospheric filtrate tank that will flash off any heat value above boiling point.

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Claims (9)

  1. Procédé de cuisson de matière cellulosique triturée, dans ledit procédé on utilise un système de lessiveur continu à deux cuves comprenant une première cuve d'imprégnation atmosphérique et une seconde cuve d'imprégnation atmosphérique, dans lequel la matière cellulosique présente un temps de rétention d'au moins 40 minutes dans la première cuve d'imprégnation et d'au moins 90 minutes dans la seconde cuve d'imprégnation, et dans lequel un niveau de liqueur d'au moins 15 mètres est établit dans la première cuve d'imprégnation, ledit procédé comprenant les étapes suivantes en séquence consistant à ;
    - alimenter la matière cellulosique triturée maintenue à température ambiante à la première cuve d'imprégnation établissant un niveau de matière cellulosique au moins 4 mètres au-dessus d'un niveau de liqueur établit dans la cuve d'imprégnation ;
    - ajouter une liqueur chaude d'imprégnation à une température au-dessus du point d'ébullition à une position située à l'intérieur du volume de matière cellulosique au-dessus du niveau de liqueur, de telle sorte qu'une vapeur est libérée dans le volume de matière cellulosique destiné à la vaporisation, et dans lequel la liqueur chaude d'imprégnation à pression libérée assume une température correspondant au point d'ébullition au niveau de la liqueur établit dans la cuve d'imprégnation ;
    - la cuve d'imprégnation ayant un tamis au niveau de la liqueur et dans lequel le tamis retire au moins 1 à 2 tonnes de liqueur/bois anhydre de la liqueur d'imprégnation, ladite liqueur contenant au moins une partie de l'acidité du bois libérée pendant la vaporisation dans le volume du copeau au-dessus du niveau de la liqueur ;
    - la matière cellulosique est imprégnée de la liqueur d'imprégnation à pression libérée pendant le temps de rétention dans la cuve d'imprégnation,
    - pendant l'alimentation de matière triturée imprégnée provenant de la cuve d'imprégnation, on ajoute de la liqueur noire à une température de cuisson complète de telle sorte que la température de la suspension de transport de matière triturée au lessiveur est accrue d'au moins 10 °C ;
    - dans la partie supérieure du lessiveur on trouve au moins 4 tonnes de liqueur/bois anhydre de la suspension de transport retirée et utilisée comme la liqueur chaude d'imprégnation à la cuve d'imprégnation ;
    - et qu'une température de lessiveur complète dans l'intervalle compris entre 130 et 170 °C est établie dans une zone de cuisson dans le lessiveur utilisant au moins 80 % du temps de rétention totale dudit lessiveur en tant que zone de cuisson ;
    - ledit lessiveur ayant un tamis de lessiveur au milieu de la zone de cuisson au niveau d'une position dans le lessiveur correspondant de 35 à 60 % du temps de rétention totale dans le lessiveur, et dans lequel le tamis de cuisson retire au moins 2,5 tonnes de liqueur/bois anhydre établissant une première partie de la zone de cuisson avec un rapport L/W élevé et une seconde partie de la zone de cuisson avec un rapport L/W faible, dont la liqueur retirée est chargée pendant l'alimentation de matière triturée imprégnée depuis la cuve d'imprégnation comme liqueur noire est chargée pendant l'alimentation de matière triturée imprégnée provenant de la cuve d'imprégnation en tant que liqueur noire à température de cuisson complète caractérisé en ce qu'un volume supplémentaire d'au moins 0,5 tonne de liqueur/bois anhydre de filtrat de lavage à partir d'une position de lavage marron après que le lessiveur soit ajouté au centre de la cuve du lessiveur au niveau du tamis de lessiveur après le chauffage du filtrat de lavage à une température de lessiveur complète, ledit filtrat de lavage ayant une teneur en lignine inférieure à 50 % de la teneur en lignine dans la liqueur noire retirée dans le tamis,
    et finalement retirer une quantité correspondante de liqueur en tant que liqueur supplémentaire également provenant du tamis dans la cuve d'imprégnation utilisant ainsi la valeur calorifique du filtrat de lavage chauffé en premier dans la circulation de transfert et ensuite en tant que liqueur chaude d'imprégnation libérant plus de vapeur de la vaporisation de copeau.
  2. Procédé de cuisson de matière cellulosique triturée selon la revendication 1, caractérisé en ce qu'une liqueur alcaline fraiche est chargée sur le système de lessiveur à deux cuves en une charge totale comprise entre 160 et 190 (HW), entre 190 et 230 (SW) kg d'alcali/bois anhydre (EA en tant que NaOH) dans au moins 3 positions de traitement, dans lequel une première charge est ajoutée à la partie supérieure du lessiveur en une quantité dépassant 60 % de la charge totale de liqueur alcaline fraiche, et une deuxième charge sur la liqueur chaude d'imprégnation et une troisième charge sur le filtrat de lavage ajouté au centre de la cuve de lessiveur au niveau du tamis de lessiveur.
  3. Procédé de cuisson de matière cellulosique triturée selon la revendication 2, caractérisé en ce que la quantité de liqueur alcaline fraîche chargée sur le filtrat de lavage ajouté au centre de la cuve du lessiveur au niveau du tamis de lessiveur correspond à au moins 10 % de la charge totale de liqueur alcaline fraîche, dans lequel la charge est suffisante pour établir un niveau d'alcali dans la zone de cuisson de plus de 10 g/l, en tant que NaOH), et préférablement supérieur à 15 g/l.
  4. Procédé de cuisson de matière cellulosique triturée selon la revendication 3, caractérisé en ce que la quantité de liqueur alcaline fraîche chargée sur le filtrat de lavage est chargée à une circulation de cuisson remettant en circulation une partie de la liqueur retirée du tamis de lessiveur au centre de la cuve de lessiveur au niveau de la position de hauteur du tamis de lessiveur, ou alternativement est chargée sur une circulation de cuisson remettant en circulation une partie de la liqueur retirée depuis un tamis de lavage vers le centre de la cuve de lessiveur au niveau de la position de hauteur du tamis de lessiveur.
  5. Procédé de cuisson de matière cellulosique triturée selon la revendication 3, caractérisé en ce que la quantité de liqueur alcaline fraîche chargée sur la liqueur chaude d'imprégnation correspond à au moins 10 % de la charge totale de la liqueur alcaline fraîche, dans lequel la charge suffisante pour établir un niveau final d'alcali résiduel dans la cuve d'imprégnation de plus de 8 g/l (en tant que NaOH), et préférablement supérieur à 15 g/l.
  6. Procédé de cuisson de matière cellulosique triturée selon la revendication 1, caractérisé en ce que le filtrat de lavage à partir d'une position ultérieure de lavage marron après que le lessiveur soit obtenu à partir d'un lavage pressurisé, maintenant la pression du filtrat de lavage avant l'addition au lessiveur.
  7. Procédé de cuisson de matière cellulosique triturée selon la revendication 6, caractérisé en ce que le filtrat de lavage à partir d'une position ultérieure de lavage marron après que le lessiveur soit obtenu à partir d'un lavage pressurisé, maintenant la température du filtrat de lavage avant l'addition au lessiveur au-dessus de 100 °C, et de préférence dans la plage comprise entre 100 et 110 °C.
  8. Procédé de cuisson de matière cellulosique triturée selon la revendication 7, caractérisé en ce que le filtrat de lavage est obtenu à partir d'une position ultérieure de lavage marron immédiatement après le lessiveur, de préférence dans un diffuseur de pression.
  9. Procédé de cuisson de matière cellulosique triturée selon la revendication 1, caractérisé en ce que le filtrat de lavage à partir d'une position ultérieure de lavage marron après que le lessiveur soit obtenu à partir d'un lavage après une étape de délignification d'oxygène, maintenant la température du filtrat de lavage avant le chauffage et l'addition au lessiveur dans la plage comprise entre 85 et 95 °C ou plus.
EP15857624.9A 2014-11-07 2015-11-04 Procédé de fonctionnement d'un système de digesteur à deux cuves Active EP3215672B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE1451340A SE538452C2 (en) 2014-11-07 2014-11-07 Method for operating a two vessel digester system
PCT/SE2015/051161 WO2016072919A1 (fr) 2014-11-07 2015-11-04 Procédé de fonctionnement d'un système de digesteur à deux cuves

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CL (1) CL2017001066A1 (fr)
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WO2017204736A1 (fr) * 2016-05-27 2017-11-30 Valmet Ab Charge d'alcali double pour imprégnation de copeau

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US5536366A (en) * 1993-05-04 1996-07-16 Ahlstrom Machinery Inc. Digester system for implementing low dissolved solids profiling
US5522958A (en) * 1994-07-18 1996-06-04 Pulp And Paper Research Institute Of Canada Two-stage kraft cooking
SE9802844D0 (sv) * 1998-08-24 1998-08-24 Kvaerner Pulping Tech Method for continuous cooking of lignocellulosic fibre material
FI990127A0 (fi) * 1999-01-22 1999-01-22 Ahlstrom Machinery Oy Menetelmä massan käsittelemiseksi
SE0200185L (sv) * 2002-01-24 2002-12-10 Kvaerner Pulping Tech Förfarande för att öka värmeekonomin i kokarsystemet vid kontinuerlig kokning
FI123023B (fi) * 2009-09-01 2012-10-15 Andritz Oy Menetelmä ja laitteisto suovan erottamiseksi

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BR112017009620A2 (pt) 2017-12-19
EP3215672A1 (fr) 2017-09-13
SE538452C2 (en) 2016-07-05
EP3215672A4 (fr) 2018-05-02
SE1451340A1 (sv) 2016-05-08
WO2016072919A1 (fr) 2016-05-12
CL2017001066A1 (es) 2017-12-29
BR112017009620B1 (pt) 2022-04-12

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