EP0308314B1 - Process for the ozone treatment of lignocellulosic materials, in particular paper pulps, and reactor for carrying out this process - Google Patents

Process for the ozone treatment of lignocellulosic materials, in particular paper pulps, and reactor for carrying out this process Download PDF

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Publication number
EP0308314B1
EP0308314B1 EP88402296A EP88402296A EP0308314B1 EP 0308314 B1 EP0308314 B1 EP 0308314B1 EP 88402296 A EP88402296 A EP 88402296A EP 88402296 A EP88402296 A EP 88402296A EP 0308314 B1 EP0308314 B1 EP 0308314B1
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Prior art keywords
ozone
enclosure
mechanical
reactor
carrier gas
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German (de)
French (fr)
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EP0308314A1 (en
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Christian Coste
Pierre Jan
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Suez International SAS
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Degremont SA
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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
    • 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
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
    • D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone

Definitions

  • the present invention relates to the treatment with ozone of lignocellulosic material and in particular of paper pulps of the chemico-thermo-mechanical, mechanical, thermo-mechanical type.
  • ozone has an action on lignocellulosic materials in general and in particular on lignin. This action, which leads to chemical degradation resulting in elimination of the wood structure, has been used for bleaching, in particular pulp.
  • ozonization has not made evident the favorable influence of ozone on the improvement of the paper qualities, in particular of the mechanical qualities of certain pulps, like that of so-called “thermo-mechanical”, “mechanical”, “chemico-thermo-mechanical” dough, that is to say dough obtained by grating logs in a humid environment on grinding stones, or by shredding chips previously softened with water or steam, with a slight chemical and / or heat treatment.
  • a process for bleaching chemical pulp with ozone of paper which consists in treating a pulp previously brought to a desired hygrometric state and to a surface state which is suitable for ensuring good contact between ozone and pulp.
  • Such a process is not entirely satisfactory, in particular as regards the mechanical properties of the material obtained when it is a question of pasta of the mechanical, thermo-mechanical or chemico-thermo-mechanical type.
  • the present invention proposes to provide a method of treatment with ozone, improved compared to the prior art and providing unexpected results which will be reported below.
  • an interface of maximum value is characterized in that the ozone concentration of the carrier gas is between 4 and 10% by mass relative to said carrier gas, and in that the amount of ozone introduced is between 2 and 8% by mass relative to the dry matter .
  • the material is treated before ozonation by any means whatsoever, so that its dryness is in a range between 20 and 50%.
  • the improvement of the paper qualities of the finished products obtained after treatment with ozone according to the process according to the invention also makes it possible to increase the productivity by a significant gain on the speed of manufacture of paper or cardboard, as well as by an increase. speeds of machines ensuring processing or final use, printing, for example.
  • the Applicant has also been able to demonstrate that, when the treatment with ozone is carried out in accordance with the process according to the invention, the compounds with aromatic structure which constitute the lignin framework are transformed into by-products no longer having the benzene function.
  • This transformation has the advantage of limiting the weight loss due to the disappearance of the lignin to a minimal value and of retaining an excellent yield by weight of the lignocellulosic materials thus treated.
  • a manufacture of paper pulp according to a conventional chemical process makes it possible to obtain an overall yield of the order of 45 to 60% while a manufacture of pulp according to a process according to the invention makes it possible to obtain a yield by weight of the order of 90% with an ozone level equal to 5% by mass relative to the material considered dry.
  • Ozone is produced from oxygen carried by a pipe (1) and introduced into a generator (2) electrically supplied at medium frequency and cooled with chilled water brought by a pipe (3) and evacuated by a pipe ( 4).
  • the characteristics of this generator are chosen so as to obtain high ozone concentrations of between 70 and 140 g / Nm3.
  • the highly concentrated ozone gas thus produced is sent via a pipe (5) to a reactor (6) constituted by an elongated enclosure slightly inclined to the horizontal in which the flow and mixing of the cellulosic material to be ozonated is ensured by a simple screw system (7) like Archimedes screw provided with a cleaning device (not shown) and ensuring a propulsion and a flow of the lignocellulosic material to be treated and favoring a continuous renewal of the material interface -gas.
  • the reactions of ozone on the lignocellulosic structures passing through a maximum depending on the height of the layer of material to be treated, the assembly is designed and adjusted so that the height of the layer of material being in the reactor remains weak and is advantageously around ten cm.
  • the ozonated gas is injected at several points (8) distributed over the length of the reactor by means of orifices provided in the part of the pipeline (5) located inside the reactor so as to ensure a radial flow of interest over the entire volume. reactive.
  • a conventional flow control device (not shown) allows this flow to be adjusted in each of the reaction zones defined by the injection points.
  • the introduction of lignocellulosic material into the reactor (6) takes place using a hopper (9) supplying a screw (10) of the plug type ensuring both the regulation of the rate of introduction of the material in the reaction vessel and the seal necessary to prevent leakage of ozonated gas to the atmosphere.
  • the extraction of the lignocellulosic material treated at the outlet of the reactor is carried out by means of a screw (11) also of the plug type ensuring both the regulation of the flow rate of the extracted product and the tightness necessary to prevent leakage of ozonated gas to the atmosphere.
  • the lignocellulosic material is brought, before its introduction into the ozonization reactor, by any means or any device suitable for a state of controlled dryness between 30 and 45% humidity.
  • the residence time of the lignocellulosic material necessary to obtain the desired paper qualities is adjusted by adjusting the speed of rotation of the screw (7) ensuring the progression of the material in the treatment enclosure.
  • the small quantity of ozone which has not reacted with the lignocellulosic material is extracted from the reactor by suction and directed by a pipe (12) to a unit (14) for ozone destruction by thermal means.
  • the breaking length represents the length in meters of a strip of uniform width thickness supposed to be suspended by one of its ends and breaking under the effect of its own weight.
  • the burst index is an index reflecting the force to be applied, by means of a device capable of exerting hydrostatic pressure on a paper sample to cause it to burst.

Abstract

Process for the ozone treatment of lignocellulosic material, especially of paper pulp, according to which the material is brought to the desired moisture content beforehand in order that the ozonation reaction may take place under optimum conditions, characterised in that the material brought to the desired moisture content is reduced to a sufficient state of division to ensure an interface of maximum value between the ozone-carrier gas and the fibrous solid and in that the said material is then subjected to ozonation by means of a carrier gas in which the ozone concentration is between 4 and 10% on a mass basis in relation to the said carrier gas. <IMAGE>

Description

La présente invention concerne le traitement par l'ozone de matériau ligno-cellulosique et notamment de pâtes à papier du type chimico-thermo-mécanique, mécanique, thermo-mécanique.The present invention relates to the treatment with ozone of lignocellulosic material and in particular of paper pulps of the chemico-thermo-mechanical, mechanical, thermo-mechanical type.

Il est connu que l'ozone a une action sur les matériaux lignocellulosiques en général et en particulier sur la lignine. Cette action, qui conduit à une dégradation chimique se traduisant par une élimination de la structure ligneuse, a été utilisée pour le blanchiment, en particulier de pâtes à papier.It is known that ozone has an action on lignocellulosic materials in general and in particular on lignin. This action, which leads to chemical degradation resulting in elimination of the wood structure, has been used for bleaching, in particular pulp.

On a constaté que le traitement des pâtes à papier par l'ozone, appliqué pendant la phase de raffinage, entraînait une réduction de l'énergie globale nécessaire à ce raffinage au prix cependant d'une augmentation de la durée de cette phase, donc du traitement, en raison de la lenteur de la réaction de l'ozone sur la pâte.It has been found that the treatment of paper pulps with ozone, applied during the refining phase, leads to a reduction in the overall energy required for this refining at the cost, however, of an increase in the duration of this phase, therefore of the processing, due to the slow reaction of ozone on the dough.

Par ailleurs, l'ozonation, telle qu'elle a été mise en oeuvre jusqu'à maintenant n'a pas rendu évidente l'influence favorable de l'ozone sur l'amélioration des qualités papetières, notamment des qualités mécaniques de certaines pâtes, comme celles des pâtes dites "thermo-mécaniques", "mécaniques", "chimico-thermo-mécaniques", c'est-à-dire des pâtes obtenues par râpage de rondins en milieu humide sur des meules, ou par déchiquetage de copeaux prèalablement ramollis à l'eau ou à la vapeur, avec un léger traitement chimique et/ou thermique.In addition, ozonization, as it has been implemented up to now, has not made evident the favorable influence of ozone on the improvement of the paper qualities, in particular of the mechanical qualities of certain pulps, like that of so-called "thermo-mechanical", "mechanical", "chemico-thermo-mechanical" dough, that is to say dough obtained by grating logs in a humid environment on grinding stones, or by shredding chips previously softened with water or steam, with a slight chemical and / or heat treatment.

On connaît (voir document FR-A-1 441 787) un procédé de blanchiment à l'ozone de pâtes à papier de type chimique qui consiste à traiter une pâte préalablement amenée à un état hygrométrique voulu et à un état de surface propre à assurer un bon contact entre l'ozone et la pâte à papier. Un tel procédé ne donne pas entière satisfaction, notamment en ce qui concerne les propriétés mécaniques du matériau obtenu lorsqu'il s'agit de pâtes du type mécanique, thermo-mécanique ou chimico-thermo-mécanique.A process is known (see document FR-A-1 441 787) for bleaching chemical pulp with ozone of paper which consists in treating a pulp previously brought to a desired hygrometric state and to a surface state which is suitable for ensuring good contact between ozone and pulp. Such a process is not entirely satisfactory, in particular as regards the mechanical properties of the material obtained when it is a question of pasta of the mechanical, thermo-mechanical or chemico-thermo-mechanical type.

La présente invention se propose d'apporter un procédé de traitement par l'ozone, amélioré par rapport à l'état antérieur de la technique et procurant des résultats inattendus dont il sera fait état ci-après.The present invention proposes to provide a method of treatment with ozone, improved compared to the prior art and providing unexpected results which will be reported below.

Le procédé suivant l'invention, pour le traitement de pates à papier du type chimico-thermo-mécanique, mécanique, thermo-mécanique, en vue d'en accroître les qualités mécaniques, suivant lequel la pâte à papier amenée à un état de siccité se situant dans une plage comprise entre 20 et 50 % d'humidité, est réduite à un état de division suffisant pour amener entre elle et le gaz vecteur d'ozone à l'action duquel elle est soumise, une interface de valeur maximale est caractérisé en ce que la concentration en ozone du gaz vecteur se situe entre 4 et 10 % en masse par rapport audit gaz vecteur, et en ce que la quantité d'ozone introduite se situe entre 2 et 8 % en masse par rapport à la matière sèche.The process according to the invention, for the treatment of paper pulps of the chemico-thermo-mechanical, mechanical, thermo-mechanical type, with a view to increasing their mechanical qualities, according to which the paper pulp brought to a dry state lying in a range between 20 and 50% humidity, is reduced to a state of division sufficient to bring between it and the ozone carrier gas to which it is subjected, an interface of maximum value is characterized in that the ozone concentration of the carrier gas is between 4 and 10% by mass relative to said carrier gas, and in that the amount of ozone introduced is between 2 and 8% by mass relative to the dry matter .

La demanderesse a constaté qu'en opérant conformément au procédé défini ci-dessus, on obtenait des résultats surprenants en ce qui concerne non seulement la diminution de la durée de réaction mais également et surtout des améliorations significatives des qualités mécaniques du matériau obtenu, en particulier de la longueur de rupture et de l'indice d'éclatement des pâtes à papier, en particulier des pâtes du type chimico-thermo-mécanique, mécanique, thermo-mécanique.The Applicant has found that by operating in accordance with the process defined above, surprising results were obtained as regards not only the reduction in the reaction time but also and above all significant improvements in the mechanical qualities of the material obtained, in particular the breaking length and the burst index of the paper pulps, in particular of the chemical-thermo-mechanical, mechanical, thermo-mechanical type.

Conformément à l'invention, le matériau est traité avant l'ozonation par tout moyen quelconque, de façon à ce que sa siccité se situe dans une plage comprise entre 20 et 50 %.According to the invention, the material is treated before ozonation by any means whatsoever, so that its dryness is in a range between 20 and 50%.

Le procédé suivant l'invention permet en particulier d'atteindre les résultats, particulièrement intéressants, suivants :

  • les temps de réaction conduisant à l'obtention d'améliorations significatives des qualités des matériaux traités sont de 10 à 30 fois plus faibles que ceux réalisés avec les procédés connus, ce qui permet d'obtenir les réactions voulues avec des durées allant de quelques secondes à une centaine de secondes.
  • les caractéristiques mécaniques du matériau traité (longueur de rupture, résistance à l'éclatement) présentent des gains pouvant atteindre 50 à 60 % par rapport aux valeurs initiales, en fonction des tau d'ozone appliqués. Ces gains considérables permettent d'améliorer les qualités du produit fini, papier ou carton de toute nature, et permettent de la même façon de réduire substantiellement les quantités des pâtes chimiques entrant dans la composition finale des mélanges destinés à la fabrication de papier présentant des qualités particulières.
The process according to the invention makes it possible in particular to achieve the following particularly advantageous results:
  • the reaction times leading to obtaining significant improvements in the qualities of the treated materials are 10 to 30 times lower than those achieved with known methods, which makes it possible to obtain the desired reactions with durations ranging from a few seconds a hundred seconds.
  • the mechanical characteristics of the treated material (rupture length, bursting strength) show gains of up to 50 to 60% compared to the initial values, depending on the tau of ozone applied. These considerable gains make it possible to improve the qualities of the finished product, paper or cardboard of all kinds, and in the same way make it possible to substantially reduce the quantities of chemical pulps entering into the final composition of the mixtures intended for the manufacture of paper having qualities particular.

L'amélioration des qualités papetières des produits finis obtenue après traitement par l'ozone selon le procédé suivant l'invention, permet également d'augmenter la productivité par un gain sensible sur la vitesse de fabrication des papiers ou cartons, ainsi que par une augmentation des vitesses des machines assurant la transformation ou l'utilisation finale, imprimerie, par exemple.The improvement of the paper qualities of the finished products obtained after treatment with ozone according to the process according to the invention also makes it possible to increase the productivity by a significant gain on the speed of manufacture of paper or cardboard, as well as by an increase. speeds of machines ensuring processing or final use, printing, for example.

La demanderesse a également pu mettre en évidence que, lorsque le traitement par l'ozone s'effectue conformément au procédé suivant l'invention, les composés à structure aromatique qui constituent l'ossature de la lignine sont transformés en sous-produits ne présentant plus la fonction benzénique.The Applicant has also been able to demonstrate that, when the treatment with ozone is carried out in accordance with the process according to the invention, the compounds with aromatic structure which constitute the lignin framework are transformed into by-products no longer having the benzene function.

Cette transformation a pour avantage de limiter la perte de poids due à la disparition de la lignine à une valeur minime et de conserver un excellent rendement en poids des matériaux ligno-cellulosiques ainsi traités. A titre d'exemple non limitatif, une fabrication de pâte à papier selon un procédé chimique classique permet d'obtenir un rendement global de l'ordre de 45 à 60 % alors qu'une fabrication de pâte selon un procédé conforme à l'invention permet d'obtenir un rendement en poids de l'ordre de 90 % avec un taux d'ozone égal à 5 % en masse par rapport au matériau considéré sec.This transformation has the advantage of limiting the weight loss due to the disappearance of the lignin to a minimal value and of retaining an excellent yield by weight of the lignocellulosic materials thus treated. By way of nonlimiting example, a manufacture of paper pulp according to a conventional chemical process makes it possible to obtain an overall yield of the order of 45 to 60% while a manufacture of pulp according to a process according to the invention makes it possible to obtain a yield by weight of the order of 90% with an ozone level equal to 5% by mass relative to the material considered dry.

Grâce au procédé suivant l'invention, il est possible d'obtenir des pâtes à papier dont les qualités papetières, comme par exemple, la longueur de rupture ou l'indice d'éclatement sont voisines de celles des pâtes obtenues par transformation chimique classique avec l'avantage d'un rendement en poids nettement favorable.Thanks to the process according to the invention, it is possible to obtain paper pulps whose paper qualities, such as for example, the length of break or the burst index are close to those of pulps obtained by conventional chemical transformation with the advantage of a clearly favorable weight yield.

Le procédé suivant l'invention peut être mis en oeuvre au moyen d'un réacteur dont on a décrit ci-après uniquement à titre d'exemple non limitatif, une forme possible de réalisation, cette description étant faite en référence au dessin annexé qui montre schématiquement une installation comportant un tel réacteur.The process according to the invention can be implemented by means of a reactor which has been described below solely by way of nonlimiting example, a possible embodiment, this description being given with reference to the appended drawing which shows schematically an installation comprising such a reactor.

L'ozone est produit à partir d'oxygène véhiculé par une canalisation (1) et introduit dans un générateur (2) alimenté électriquement en moyenne fréquence et refroidi à l'eau réfrigérfée amenée par une canalisation (3) et évacuée par une canalisation (4). Les caractéristiques de ce générateur sont choisies de façon à obtenir de fortes concentrations en ozone comprises entre 70 et 140 g/Nm3.Ozone is produced from oxygen carried by a pipe (1) and introduced into a generator (2) electrically supplied at medium frequency and cooled with chilled water brought by a pipe (3) and evacuated by a pipe ( 4). The characteristics of this generator are chosen so as to obtain high ozone concentrations of between 70 and 140 g / Nm3.

Le gaz ozoné à forte concentration ainsi produit est envoyé par une canalisation (5) dans un réacteur (6) constitué par une enceinte de forme allongée légèrement inclinée sur l'horizontale dans laquelle l'écoulement et le brassage du matériau cellulosique à ozoner sont assurés par un système de vis simple (7) genre vis d'Archimède muni d'un dispositif de débourrage (non représenté) et assurant une propulsion et un écoulement du matériau ligno-cellulosique à traiter et favorisant un renouvellement continu de l'interface matériau-gaz. Les réactions de l'ozone sur les structures ligno-cellulosiques passant par un maximum en fonction de la hauteur de la couche de matériau à traiter, l'ensemble est conçu et réglé de façon à ce que la hauteur de la couche de matériau se trouvant dans le réacteur reste faible et se situe avantageusement aux environs d'une dizaine de cm.The highly concentrated ozone gas thus produced is sent via a pipe (5) to a reactor (6) constituted by an elongated enclosure slightly inclined to the horizontal in which the flow and mixing of the cellulosic material to be ozonated is ensured by a simple screw system (7) like Archimedes screw provided with a cleaning device (not shown) and ensuring a propulsion and a flow of the lignocellulosic material to be treated and favoring a continuous renewal of the material interface -gas. The reactions of ozone on the lignocellulosic structures passing through a maximum depending on the height of the layer of material to be treated, the assembly is designed and adjusted so that the height of the layer of material being in the reactor remains weak and is advantageously around ten cm.

Le gaz ozoné est injecté en plusieurs points (8) répartis sur la longueur du réacteur grâce à des orifices ménagés dans la partie de la canalisation (5) située à l'intérieur du réacteur de manière à assurer un flux radial intéressant la totalité du volume réactionnel. Un dispositif de régulation de débit classique (non représenté) permet d'ajuster ce débit dans chacune des zones réactionnelles définies par les points d'injection.The ozonated gas is injected at several points (8) distributed over the length of the reactor by means of orifices provided in the part of the pipeline (5) located inside the reactor so as to ensure a radial flow of interest over the entire volume. reactive. A conventional flow control device (not shown) allows this flow to be adjusted in each of the reaction zones defined by the injection points.

L'introduction du matériau ligno-cellulosique dans le réacteur (6) s'opère à l'aide d'une trémie (9) alimentant une vis (10) de type bouchon assurant à la fois la régulation du débit d'introduction du matériau dans l'enceinte réactionnelle et l'étanchéité nécessaire pour éviter les fuites de gaz ozoné à l'atmosphère.The introduction of lignocellulosic material into the reactor (6) takes place using a hopper (9) supplying a screw (10) of the plug type ensuring both the regulation of the rate of introduction of the material in the reaction vessel and the seal necessary to prevent leakage of ozonated gas to the atmosphere.

De la même façon, l'extraction du matériau ligno-cellulosique traité en sortie de réacteur est réalisée par l'intermédiaire d'une vis (11) également de type bouchon assurant à la fois la régulation du débit du produit extrait et l'étanchéité nécessaire pour éviter les fuites de gaz ozoné à l'atmosphère.In the same way, the extraction of the lignocellulosic material treated at the outlet of the reactor is carried out by means of a screw (11) also of the plug type ensuring both the regulation of the flow rate of the extracted product and the tightness necessary to prevent leakage of ozonated gas to the atmosphere.

Le matériau ligno-cellulosiqu est amené, avant son introduction dans le réacteur d'ozonation, par tout moyen ou dispositif quelconque convenable à un état de siccité contrôlée se situant entre 30 et 45 % d'humidité. Le temps de séjour du matériau ligno-cellulosique nécessaire à l'obtention des qualités papetières souhaitées est ajusté par règlage de la vitesse de rotation de la vis (7) assurant la progression du matériau dans l'enceinte de traitement.The lignocellulosic material is brought, before its introduction into the ozonization reactor, by any means or any device suitable for a state of controlled dryness between 30 and 45% humidity. The residence time of the lignocellulosic material necessary to obtain the desired paper qualities is adjusted by adjusting the speed of rotation of the screw (7) ensuring the progression of the material in the treatment enclosure.

La faible quantité d'ozone n'ayant pas réagi avec le matériau ligno-cellulosique est extraite du réacteur par aspiration et dirigée par une canalisation (12) vers une unité (14) de destruction d'ozone par voie thermique.The small quantity of ozone which has not reacted with the lignocellulosic material is extracted from the reactor by suction and directed by a pipe (12) to a unit (14) for ozone destruction by thermal means.

La réaction de l'ozone sur les structures ligneuses en phase semi-humide (siccité du matériau comprise entre 20 et 50 % , conformément à l'invention) étant, comme l'a constaté la demanderesse, de type très fortement exothermique un circuit de refroidissement (13) est installé dans l'enveloppe du réacteur de façon à contrôler et à limiter l'élévation de température dans l'enceinte réactionnelle. Dans ces conditions, la température reste inférieure à 50 ° C en tous les points du réacteur ce qui limite la réaction d'auto-décomposition de l'ozone et permet d'avoir une consommation d'ozone ajustée à la seule stoechiométrie de la réaction de transformation de la lignine.The reaction of ozone on woody structures in the semi-humid phase (dryness of the material between 20 and 50%, in accordance with the invention) being, as the applicant has observed, of a very strongly exothermic type a circuit of cooling (13) is installed in the reactor casing so as to control and limit the temperature rise in the reaction enclosure. Under these conditions, the temperature remains below 50 ° C. at all points of the reactor, which limits the self-decomposition reaction of the ozone and makes it possible to have an ozone consumption adjusted to the only stoichiometry of the reaction. lignin processing.

Au moyen d'un réacteur tel que celui qui vient d'être décrit on a obtenu les résultats consignés dans le tableau suivant : Caractéristiques Traitement classsique à l'ozone Traitement suivant d'invention Siccité du matériau ( % ) 40 40 Taux d'ozone (Pourcentage massique par rapport à la matière sèche) 5 5 Concentration en ozone dans l'oxygène (Pourcentage massique) 2 6 Température du réacteur ( °C ) 85 °C environ 35 °C Temps de contact (Durée de la réaction) (Secondes) 1 200 40 Caractéristiques papetières du matériau brut : L = Longueur de rupture (m) 4 500 4 500 I = Indice d'éclatement 20 20 Gains : - Durée de la réaction 30 fois plus courte - Longueur de rupture ( % ) ÷ 15 ÷ 50 - Indice d'éclatement ( % ) ÷ 15 ÷ 60 By means of a reactor such as that which has just been described, the results given in the following table have been obtained: Characteristics Classic ozone treatment Next invention treatment Material dryness (%) 40 40 Ozone level (percentage by mass relative to dry matter) 5 5 Ozone concentration in oxygen (mass percentage) 2 6 Reactor temperature (° C) 85 ° C about 35 ° C Contact time (reaction time) (seconds) 1,200 40 Paper characteristics of the raw material: L = Break length (m) 4,500 4,500 I = Burst index 20 20 Earnings : - Duration of the reaction 30 times shorter - Break length (%) ÷ 15 ÷ 50 - Burst index (%) ÷ 15 ÷ 60

La longueur de rupture représente la longueur en mètre d'une bande d'épaisseur largeur uniformes supposée suspendue par une de ses extrémités et se rompant sous l'effet de son propre poids.
L'indice d'éclatement est un indice rendant compte de l'effort devant être appliqué, par l'intermédiaire d'un dispositif susceptible d'exercer une pression hydrostatique à un échantillon de papier pour provoquer son éclatement Ce tableau montre de façon éloquente les avantages que présente l'invention notamment en ce qui concerne la durée de la réaction (temps de contact) et les caractéristiques papetières du produit traité.The breaking length represents the length in meters of a strip of uniform width thickness supposed to be suspended by one of its ends and breaking under the effect of its own weight.
The burst index is an index reflecting the force to be applied, by means of a device capable of exerting hydrostatic pressure on a paper sample to cause it to burst. This table eloquently shows the advantages of the invention, in particular with regard to the duration of the reaction (contact time) and the paper characteristics of the product treated.

Cependant, le type de réacteur décrit et représenté n'est pas le seul qui puisse être utilisé.However, the type of reactor described and shown is not the only one that can be used.

On peut également utiliser pour la mise en oeuvre du procédé suivant l'invention des réacteurs de conceptions diverses, et telles que définies ci-après.

  • Réacteur de type tunnel à lit mobile dans lequel le matériau à traiter en couche de faible épaisseur est transporté mécaniquement et traversé par le gaz de traitement dont le flux est réparti sur toute la surface du lit pour homogénéiser l'attaque du matériau par le gaz de traitement;
  • Réacteur dont l'enceinte en forme de corps de révolution avantageusement cylindrique et animée d'un mouvement de rotation autour de son axe, l'enceinte étant munie au moins d'un dispositif provoquant une turbulence de manière à perturber l'écoulement dans l'enceinte du matériau à traiter ;
  • Réacteur dont l'enceinte est verticale et comporte une pluralité de soles inclinées pour permettre un écoulement gravitaire du matériau solide avec utilisation de bras racleurs pour réaliser un brassage mécanique, le gaz ozoné circulant dans le même sens ou à contre-courant de l'écoulement du matériau à traiter.
It is also possible to use, for implementing the process according to the invention, reactors of various designs, and as defined below.
  • Movable bed tunnel type reactor in which the material to be treated in a thin layer is mechanically transported and traversed by the treatment gas, the flow of which is distributed over the entire surface of the bed to homogenize the attack of the material by the treatment;
  • Reactor whose enclosure in the form of an advantageously cylindrical body of revolution and which rotates about its axis, the enclosure being provided with at least one device causing turbulence so as to disturb the flow in the enclosure of the material to be treated;
  • Reactor whose enclosure is vertical and has a plurality of inclined soles to allow gravity flow of the solid material with the use of scraper arms to effect mechanical mixing, the ozonated gas circulating in the same direction or against the current of the flow of the material to be treated.

Claims (5)

  1. Process for the ozone treatment of paper pulps, of the chemico-thermo-mechanical, mechanical, or thermo-mechanical type, for the purpose of improving their mechanical properties, according to which the paper pulp brought to a dryness state in a range lying between 20 and 50% humidity is reduced to a sufficiently divided state for creating an interface of maximum value between it and the carrier gas for the ozone, to the action of which it is subjected, characterized in that the ozone concentration in the carrier gas lies between 4 and 10% by mass relative to said carrier gas, and in that the quantity of ozone introduced lies between 2 and 8% by mass relative to the dry material.
  2. Reactor for carrying out the process according to Claim 1, of the type constituted of an enclosure having the shape of a body of revolution, into which are introduced the ozone-containing gas and the paper pulp, comprising means for the introduction of the pulp and its discharge after reaction, characterized in that the feed pipe (5) for the ozone-containing gas into the enclosure (6) has a plurality of orifices (8), through which the ozone-containing gas is injected into the enclosure, in such a way as to ensure a radial flow affecting the entirety of the reaction volume, and in that said enclosure (6) is provided with means (7) for maintaining the material to be treated in a thin layer and which assure a continuous renewal of the interface between material and treatment gas.
  3. Reactor according to Claim 2, characterized in that the enclosure is vertical and comprises a plurality of inclined floors for allowing a gravitational flow of the solid material, scraper arms being provided for performing a mechanical stirring and the ozone-containing treatment gas circulating in the same direction or in contra-current to the flow of the material to be treated.
  4. Reactor according to Claim 2, characterized in that the layer of material to be treated is situated there in a thickness of about 10 centimetres.
  5. Reactor according to Claim 2, characterized in that the enclosure (6) is inclined to the horizontal.
EP88402296A 1987-09-17 1988-09-12 Process for the ozone treatment of lignocellulosic materials, in particular paper pulps, and reactor for carrying out this process Expired - Lifetime EP0308314B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88402296T ATE82340T1 (en) 1987-09-17 1988-09-12 PROCESS FOR THE OZONE TREATMENT OF LIGNOCELLULOSIC MATERIALS, ESPECIALLY PAPER PULP, AND REACTOR FOR CARRYING OUT THE PROCESS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8712890A FR2620744A1 (en) 1987-09-17 1987-09-17 PROCESS FOR THE OZONE TREATMENT OF LIGNO-CELLULOSIC MATERIALS, IN PARTICULAR PAPER PULP AND REACTOR FOR THE IMPLEMENTATION OF SAID METHOD
FR8712890 1987-09-17

Publications (2)

Publication Number Publication Date
EP0308314A1 EP0308314A1 (en) 1989-03-22
EP0308314B1 true EP0308314B1 (en) 1992-11-11

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EP88402296A Expired - Lifetime EP0308314B1 (en) 1987-09-17 1988-09-12 Process for the ozone treatment of lignocellulosic materials, in particular paper pulps, and reactor for carrying out this process

Country Status (10)

Country Link
EP (1) EP0308314B1 (en)
JP (1) JP2731822B2 (en)
AT (1) ATE82340T1 (en)
BR (1) BR8804806A (en)
CA (1) CA1314664C (en)
DE (2) DE308314T1 (en)
ES (1) ES2035339T3 (en)
FI (1) FI93867C (en)
FR (1) FR2620744A1 (en)
NO (1) NO174781C (en)

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US5164044A (en) 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5164043A (en) 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5188708A (en) 1989-02-15 1993-02-23 Union Camp Patent Holding, Inc. Process for high consistency oxygen delignification followed by ozone relignification
US5554259A (en) 1993-10-01 1996-09-10 Union Camp Patent Holdings, Inc. Reduction of salt scale precipitation by control of process stream Ph and salt concentration

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US5472572A (en) * 1990-10-26 1995-12-05 Union Camp Patent Holding, Inc. Reactor for bleaching high consistency pulp with ozone
US5409570A (en) * 1989-02-15 1995-04-25 Union Camp Patent Holding, Inc. Process for ozone bleaching of oxygen delignified pulp while conveying the pulp through a reaction zone
US5181989A (en) * 1990-10-26 1993-01-26 Union Camp Patent Holdings, Inc. Reactor for bleaching high consistency pulp with ozone
US5211811A (en) * 1989-02-15 1993-05-18 Union Camp Patent Holding, Inc. Process for high consistency oxygen delignification of alkaline treated pulp followed by ozone delignification
FI89516B (en) * 1989-05-10 1993-06-30 Ahlstroem Oy Foerfarande Foer blekning av cellulosamassa med Otson
AT395180B (en) * 1989-08-16 1992-10-12 Andritz Ag Maschf METHOD FOR CRUSHING MATERIALS AND SYSTEM FOR IMPLEMENTING IT
US5441603A (en) * 1990-05-17 1995-08-15 Union Camp Patent Holding, Inc. Method for chelation of pulp prior to ozone delignification
US5174861A (en) * 1990-10-26 1992-12-29 Union Camp Patent Holdings, Inc. Method of bleaching high consistency pulp with ozone
US5520783A (en) * 1990-10-26 1996-05-28 Union Camp Patent Holding, Inc. Apparatus for bleaching high consistency pulp with ozone
EP0492040A1 (en) * 1990-12-21 1992-07-01 Kamyr, Inc. Tumbling ozone reactor for paper pulp
EP0492039A1 (en) * 1990-12-27 1992-07-01 Kamyr, Inc. Pneumatic reactor ozone bleaching of paper pulp
US5087326A (en) * 1991-02-20 1992-02-11 Union Camp Patent Holding, Inc. Rotating pulp bleaching reactor having inner and outer shells and lifting means on the interior surface of the inner shell
US5411633A (en) * 1991-04-30 1995-05-02 Kamyr, Inc. Medium consistency pulp ozone bleaching
DE69221385T2 (en) * 1991-05-24 1997-12-11 Union Camp Patent Holding Two-stage pulp bleaching reactor and method for bleaching with ozone
FI925558A (en) * 1992-04-22 1993-10-23 Ahlstroem Oy FOERFARANDE OCH ANORDNING FOER BLEKNING AV MASSA
US5387317A (en) * 1993-01-28 1995-02-07 The Mead Corporation Oxygen/ozone/peracetic aicd delignification and bleaching of cellulosic pulps
US5810973A (en) * 1993-09-21 1998-09-22 Beloit Technologies, Inc. Apparatus for producing small particles from high consistency wood pulp
WO1996005365A1 (en) * 1994-08-11 1996-02-22 Beloit Technologies, Inc. Means for gas-sealingly conveying shredded pulp
US5944952A (en) * 1995-07-26 1999-08-31 Beloit Technologies, Inc. Method for bleaching high consistency pulp with a gaseous bleaching reagent
US6077396A (en) * 1997-05-16 2000-06-20 Lariviere; Christopher J. Apparatus for fluffing and contacting high consistancy wood pulp with a gaseous bleaching reagent
US6174409B1 (en) 1997-09-19 2001-01-16 American Air Liquide Inc. Method to improve final bleached pulp strength properties by adjusting the CI02:03 ration within a single (D/Z) stage of the bleaching process
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FR2811320B1 (en) * 2000-07-06 2002-08-23 Adir NOVEL ALPHA CRYSTALLINE FORM OF TERT-BUTYLAMINE SALT OF PERINDOPRIL, PREPARATION METHOD THEREOF AND PHARMACEUTICAL COMPOSITIONS CONTAINING THE SAME

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FR2609067B1 (en) * 1986-12-31 1990-06-15 Beghin Say Sa PROCESS FOR THE OZONE TREATMENT OF A CELLULOSIC PASTE

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5188708A (en) 1989-02-15 1993-02-23 Union Camp Patent Holding, Inc. Process for high consistency oxygen delignification followed by ozone relignification
US5164044A (en) 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5164043A (en) 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5554259A (en) 1993-10-01 1996-09-10 Union Camp Patent Holdings, Inc. Reduction of salt scale precipitation by control of process stream Ph and salt concentration
US5693184A (en) 1993-10-01 1997-12-02 Union Camp Patent Holding, Inc. Reduction of salt scale precipitation by control of process stream pH and salt concentration

Also Published As

Publication number Publication date
FI93867C (en) 1995-06-12
EP0308314A1 (en) 1989-03-22
NO174781C (en) 1994-07-06
NO884128D0 (en) 1988-09-16
BR8804806A (en) 1989-04-25
FI884267A0 (en) 1988-09-16
NO884128L (en) 1989-03-20
JP2731822B2 (en) 1998-03-25
DE3875893D1 (en) 1992-12-17
JPH0197290A (en) 1989-04-14
FI884267A (en) 1989-03-18
DE3875893T2 (en) 1993-03-18
ATE82340T1 (en) 1992-11-15
DE308314T1 (en) 1989-10-05
FI93867B (en) 1995-02-28
NO174781B (en) 1994-03-28
CA1314664C (en) 1993-03-23
ES2035339T3 (en) 1993-04-16
FR2620744A1 (en) 1989-03-24

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