WO2017204736A1 - Charge d'alcali double pour imprégnation de copeau - Google Patents

Charge d'alcali double pour imprégnation de copeau Download PDF

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Publication number
WO2017204736A1
WO2017204736A1 PCT/SE2017/050555 SE2017050555W WO2017204736A1 WO 2017204736 A1 WO2017204736 A1 WO 2017204736A1 SE 2017050555 W SE2017050555 W SE 2017050555W WO 2017204736 A1 WO2017204736 A1 WO 2017204736A1
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WO
WIPO (PCT)
Prior art keywords
impregnation
liquor
alkali
withdrawal screen
charge
Prior art date
Application number
PCT/SE2017/050555
Other languages
English (en)
Inventor
Fredrik Wilgotson
Eduardo DEUD
Original Assignee
Valmet 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 Valmet Ab filed Critical Valmet Ab
Priority to CN201780031762.XA priority Critical patent/CN109312537A/zh
Priority to BR112018070795A priority patent/BR112018070795A2/pt
Priority to EP17803173.8A priority patent/EP3464714A4/fr
Priority to US16/302,851 priority patent/US20190194867A1/en
Publication of WO2017204736A1 publication Critical patent/WO2017204736A1/fr

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Classifications

    • 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
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D21C1/06—Pretreatment of the finely-divided materials before digesting with alkaline reacting compounds
    • 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
    • D21C7/00—Digesters
    • D21C7/06—Feeding devices
    • 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
    • D21C7/12—Devices for regulating or controlling

Definitions

  • the present invention relates generally to the impregnation of wood chips during the manufacture of chemical pulp, and in particular to an atmospheric impregnation vessel receiving chips without preceding steam treatment and a method for the alkali charging in such an impregnation vessel, and even more particularly to an impregnation vessel and a method for double alkali charging in the atmospheric impregnation vessel.
  • wood chips were subjected to a steam pretreatment before being supplied to the actual cooking process.
  • the pretreatment comprised a first heating of the chips to a temperature of 70-100 °C using low-pressure steam followed by a second heating of the chips to a temperature of 110-120 °C using flash steam or live low-pressure steam.
  • the thoroughly steamed chips were then converted to a slurry in a chip chute before being fed to the cooking process.
  • the first heating, the second heating and the slurry formation took place in different, separate vessels.
  • wood acidity is released, and steam condensate formed during the steam pretreatment could reach pH levels around 4-5.
  • This patent document is an example of improvement in the standard practice using Valmet ImpBinTM impregnation systems.
  • ImpBinTM systems is conventionally the entire alkali charge for the chip impregnation charged at the same outlet height in a first upper central pipe, using the residual alkali in hot black liquor.
  • the system described in this patent document also discloses how a first withdrawal screen ensure withdrawal of most of the parasitic wood acidity released, and followed by a second withdrawal screen that recirculate the withdrawn impregnation liquor for adequate mixing of chips and impregnation liquor over the entire cross section, but then without most of the wood acidity already withdrawn from preceding withdrawal screen.
  • the withdrawal screens are arranged preferably arranged relatively close to the top of the impregnation vessel, in order to establish even alkali level for the remaining impregnation process that occurs at low temperature starting at 100 °C (due to atmospheric vessel), which requires long time for the alkali to penetrate into the core of the chips.
  • the recirculated impregnation liquor from the second withdrawal screen may be diluted with alkaline wash liquors. But the system becomes insensitive for changes in the process as the first withdrawal may establish conditions, i.e. low pH, that clog up the first withdrawal screen, and the second withdrawal and recirculation may establish non-ideal alkali level for the impregnation that takes place below the second withdrawal screen.
  • a general object of the present invention is therefore to reduce the operating costs associated with a chip impregnation process by enabling as low charge of alkali as possible during the impregnation. Yet an objective is to adapt the charging conditions towards minimal alkali charge in response to changes in wood material fed to process and amount of water brought in with the chips. The amount of water may change within an hour or shorter as it may depend upon from what part of a wood stack the chips are collected, and may change due to snow, rain or length of storage time for the chips.
  • a further obj ective is to adapt the charging conditions towards minimal alkali charge in response to changes in residual alkali level in the hot black liquor being fed to the impregnation.
  • the hot black liquor is withdrawn from a fixed position during the cook and in a continuous digester in a screen section in the digester where the residual alkali level is fairly steady during a normal cook.
  • the residual alkali level in the hot black liquor may change as the wood material may have differing lignin content that consumes alkali.
  • the cooking process changes due to increased or lowered production, that may require change in temperature and/or charge of alkali to the cook, the residual alkali level will fluctuate.
  • Another object is to lower the overall white liquor charge, to thereby reduce fuel consumption in a lime kiln.
  • a further object is to reduce the amount of residual alkali going to evaporation, which leads lower inorganic load in the recovery boiler.
  • a still further object is to provide a more even alkali profile in an impregnation vessel, thereby leading to an improved and, in particular, more homogenous pulp quality.
  • the inventive method for the impregnation of chips during the manufacture of chemical pulp is the method comprising the following steps: a) continuously feeding chips without preceding steam treatment to the top of an atmospheric impregnation vessel, from the bottom of which impregnated chips are fed out; b) charging a first charge of impregnation liquor comprising hot black liquor to the centre of the impregnation vessel via a first central pipe having an outlet located at the level of an upper withdrawal screen located close to the impregnation liquor level established in the impregnation vessel and releasing steam from the hot black liquor for steaming the chips located above the impregnation liquor level; c) withdrawing an amount of spent impregnation liquor from the impregnation vessel by the upper withdrawal screen and sending the spent impregnation fluid with its content of released wood acidity from chip steaming to recovery; d) measuring the alkali content in the spent impregnation liquor withdrawn by the upper withdrawal screen and comparing this measured alkali content with a target value for
  • Hot black liquor added in the central pipe may have differing residual content of alkali and the additional alkali charge corrects the alkali content.
  • the impregnation process will thus not be affected by changes in the latter cooking process producing the hot spent cooking liquor.
  • the remaining impregnation liquor below the upper withdrawal screen may be adjusted by controlled addition of alkali into the recirculation, guaranteeing that the proper alkali concentration is established for the entire impregnation time below the lower withdrawal screen.
  • steps a) to h) also improves the impregnation process as:
  • the impregnation process becomes insensitive of differing cellulose material being added, that differs in wood acidity release.
  • the impregnation process becomes insensitive of differing water content in the cellulose material being added, that may differ due to natural moisture change during storage, or due to increased introduction of snow and ice with the cellulose material during cold climate operation and using conventional open storage of the cellulose material in piles.
  • Each ton of water added with the cellulose material tend to affect the pH level during wood acidity release.
  • the first charge of impregnation liquor comprising additional charge of alkaline liquor with an alkali concentration higher than the residual alkali concentration of the hot black liquor.
  • alkaline liquors from different part of the pulp mill may be used, such as: alkaline wash filtrate from digester wash or pulp bleaching wash, weak liquor from caustization, and green liquor from caustization.
  • the additional charge of alkaline liquor comprise white liquor and wherein the amount of white liquor added into the first charge of impregnation liquor is regulated to achieve the target value for the alkali content withdrawn by the upper withdrawal screen.
  • White liquor as the source having highest alkali concentration may be used as this requires less charge in volume. This white liquor may also be substituted by oxidised white liquor.
  • the second charge of impregnation liquor comprising additional charge of alkaline liquor with an alkali concentration higher than the residual alkali concentration in the impregnation liquor withdrawn by the lower withdrawal screen.
  • the alkaline liquor may comprise white liquor or any liquor with higher alkali concentration than the impregnation liquor withdrawn by the lower withdrawal screen and wherein the amount of alkaline liquor added into the second charge of impregnation liquor is regulated to achieve the target value for the alkali content below the lower withdrawal screen.
  • the alkali content established in the impregnation liquor by said second charge of impregnation liquor be measured in the flow of impregnation liquor withdrawn from the lower withdrawal screen.
  • the alkali content of the liquor withdrawn is the same as that remaining in the chips close to the wall of the impregnation vessel, and is thus the alkali content also immediately below the lower withdrawal screen. But applying a sensor in the withdrawal pipe is the best application of a sensor.
  • the alkali content established in the impregnation liquor by said second charge of impregnation liquor be measured in, or at an outlet of the impregnation vessel at a distance below the lower withdrawal screen.
  • Such measurements may be made by a sensor in or at the outlet from the impregnation vessel or a sensor in a liquor withdrawal line in the very bottom of the impregnation vessel.
  • a sensor in or at the outlet from the impregnation vessel or a sensor in a liquor withdrawal line in the very bottom of the impregnation vessel Such a positioning of a sensor could effectively monitor that the pH has been kept sufficiently high throughout the entire impregnation stage.
  • inventive method may also essentially all of the liquor withdrawn by the lower withdrawal screen be collected in a second collection volume and thereafter returned to the impregnation vessel via a pipe connected to the second collection volume and the second central pipe. This would strengthen the radial equalization flow that is established between the outlet of the second central pipe and the lower withdrawal screen, establishing an even alkali profile also over the entire cross section (from centre to wall) of the impregnation vessel.
  • inventive atmospheric impregnation vessel for the impregnation of chips during the manufacture of chemical pulp comprises:
  • an upper withdrawal screen arranged at a first level in a vessel wall of the impregnation vessel
  • a first central pipe connected in one end to a source supplying hot black liquor and having an outlet at the other end located at the first level of the upper withdrawal screen; a pipe connected in one end to an alkali source and with an outlet connected in the other end to the first central pipe and provided with a first regulating valve for regulating an additional charge of alkali into the first charge of impregnation liquor charged to the impregnation vessel via the first central pipe;
  • a second central pipe connected in one end to the lower withdrawal screen and with an outlet arranged at the level of the lower withdrawal screen.
  • Said design further comprising: one pipe connected in one end to an alkali source and with an outlet connected in the other end to the first central pipe and provided with a first regulating valve for regulating an additional charge of alkali into the first charge of impregnation liquor charged to the impregnation vessel via the first central pipe;
  • FIG. 1 is schematic illustration of the upper portion of an impregnation vessel for the impregnation of wood chips during the manufacture of chemical pulp;
  • Fig. 2 is schematic illustration of an alternative liquor routing in the upper portion of an impregnation vessel for the impregnation of wood chips during the manufacture of chemical pulp.
  • the impregnation vessel 1 comprises an essentially cylindrical vessel wall 2, in which a first withdrawal screen 3 is arranged at a first level and in which a second withdrawal screen 4 is arranged at a second level below the first level. Since the first level is above the second level, the first withdrawal screen 3 is also referred to as the upper withdrawal screen 3, while the second withdrawal screen 4 is alternatively referred to as the lower withdrawal screen 4. Liquor withdrawn by the upper withdrawal screen 3 is collected in a first collection volume 5 arranged in the vessel wall 2, while liquor withdrawn by the lower withdrawal screen 4 is collected in a second collection volume 6.
  • the impregnation vessel 1 comprises further a first central pipe 7 having an outlet 8, which in the embodiment shown Fig. 1 is arranged slightly above the first level of the first withdrawal screen 3.
  • the outlet 8 could, however, be arranged slightly below the first level of the first withdrawal screen 3, or be arranged at the same level as the first level of the first withdrawal screen 3.
  • the exact position of an outlet of a first central pipe relative the level of a first withdrawal screen is not crucial to successfully exploit the advantages of the present invention, and it suffices that an outlet of a first central pipe is located at approximately the level of a first or upper withdrawal screen.
  • the impregnation vessel 1 comprises further a second central pipe 9 having an outlet 10, which in Fig. 1 is arranged slightly above the second level of the second withdrawal screen 4, but - as for the outlet 8 of the first central pipe 7 - it is sufficient that the outlet 10 is located at approximately the second level of the second withdrawal screen 4.
  • a single first central pipe like first central pipe 7, which ends at the level of an upper withdrawal screen
  • several central pipes with smaller dimensions can be used, or the outlet of a first central pipe, like outlet 8 of first central pipe 7, can be split into several outlets, to obtain a better distribution of the heat added via the first impregnation liquor and also to reduce the alkali gradient due to neutralization reactions taking place during the radial displacement of the impregnation liquor.
  • a second central pipe 9, which ends at the level of a lower withdrawal screen can be replaced with several central pipes with smaller dimensions, or the outlet of a second central pipe, like outlet 10 of second central pipe 9, can be split into several outlets.
  • spent liquor withdrawn by the upper withdrawal screen 3 and collected in the first collection volume 5 is sent to evaporation for recovery REC, which in Fig. 1 takes place via a pipe 11, which is in liquor communication with the upper withdrawal screen 3 via the first collection volume 5.
  • the liquor withdrawn by the lower withdrawal screen 4 and collected in the second collection volume 6 is fed into a pipe 12, which is in liquor communication with the lower withdrawal screen 4 via the second collection volume 6.
  • the liquor withdrawn by the lower withdrawal screen 4 and led into the pipe 12 is not sent to recovery, instead the pipe 12 is connected to the second central pipe 9, and the liquor contained in the pipe 12 is thus returned into the impregnation vessel 1 (as is indicated by a dashed line in Fig. 1).
  • the system comprising the lower withdrawal screen 4, the pipe 12 and the second central pipe 9 with its outlet 10 is therefore arranged mainly for circulation of liquor, and preferably no liquor withdrawn by the lower withdrawal screen 4 is sent to recovery, although it is within the scope of the present invention that a minor portion of the liquor withdrawn by the lower withdrawal screen 4 may be sent to recovery.
  • the magnitude of the circulation flow created by the withdrawal of liquor via the second withdrawal screen 4 and the return of this withdrawn liquor via the pipe 12 and the second central pipe 9 to the impregnation vessel 1 should preferably be large enough to theoretically replace the amount of free liquor per tonne wood.
  • the impregnation liquor added to the chips via the first central pipe 7 can be a mixture of black liquor and white liquor.
  • the amount of residual effective alkali in the black liquor can be about 10-30 g/1 (as EA NaOH), while the amount of effective alkali in the white liquor can be about 100-120 g/1 (as EA NaOH).
  • the black liquor is charged via a first charging pipe 13, which, via a first regulating valve 14, is connected to the first central pipe 7, while the white liquor is charged via a second charging pipe 15, which via a second regulating valve 16, is connected to the first central pipe 7.
  • a second charging pipe can be connected to a first charging pipe such that there is only one charging pipe directly connected to a first central pipe.
  • the amount of residual alkali in the spent liquor that is withdrawn by the upper withdrawal screen 3 can be low, and can be as low as about 3-5 g/1. This could happen due to a number of reasons, such as a) excessive amount of water is brought in with the chips, that lowers alkali concentration; b) the wood acidity release can be larger than normal due to changes in the wood; c) or the residual alkali level in the hot black liquor can be lower than normal due to changed conditions in the cooking zone.
  • the sufficient alkali content in the withdrawn liquor can be at about 8 g/1, but the exact alkali concentration may differ ⁇ 2 g/1 depending upon the type of wood material being impregnated.
  • the amount of alkali in the liquor withdrawn by the upper withdrawal screen 3 can be measured by standard equipment and methods, and the amount of white liquor charged via the second charging pipe 15 is, via the second regulating valve 16, controlled to achieve a target value for the alkali residual in the liquor fed into the pipe 11 and going to evaporation. That is, if the amount alkali in the liquor withdrawn by the first withdrawal screen 3 is higher than a target value, less white liquor is charged to the central pipe 7, and if the amount of alkali residual is lower than a target value, more white liquor is charged to the central pipe 7.
  • the system can have a fix target value, e.g.
  • the alkali charged via the third charging pipe 17 is preferably in the form of white liquor; and from one point of view, the present invention provides an impregnation vessel and a method by which the total amount of white liquor needed for an effective impregnation of chips in an impregnation vessel is charged in two steps, at a first level and at a second level, with the constraint that the alkali content in the liquor withdrawn at the periphery of the first level should be kept low but above a minimum level, and that the alkali content in the impregnation liquor below the second level should be sufficiently high for the entire impregnation process.
  • the charge of alkali to the bulk part of impregnation that takes place below the second level can be kept at a minimum as only a small part is needed for any remaining neutralisation of wood acidity, and the consumption of alkali due to delignification reactions is insignificant as temperatures are about 100 °C.
  • the objective for the impregnation is to allow alkaline impregnation liquor to penetrate the chips into the core thereof, without consuming alkali during penetration due to delignification reactions. This lead to well impregnated chips and reduction of reject volumes after cook, i.e. uncooked chip fragments.
  • a liquor-to-wood ratio of about 4-7 can be established, while the liquor-to-wood ratio in a zone between first withdrawal screen 3 and second withdrawal screen 4 can be about 3-5, and a liquor-to-wood ratio of about 3-6 can be established at a level below the second withdrawal screen 4.
  • the liquor-to-wood ratio at the level of the first withdrawal screen 3 is higher than the liquor-to-wood ratio in the zone between first withdrawal screen 3 and second withdrawal screen 4, more spent liquor should be withdrawn by first withdrawal screen 3 and sent to recovery via pipe 11; and if the liquor-to-wood ratio in the zone between first withdrawal screen 3 and second withdrawal screen 4 is less than the liquor-to-wood ratio at the level below the second withdrawal screen 4, more white liquor should be added to the chips content via the third charging pipe 17 and the second central pipe 9.
  • the inventions essentially relate to an atmospheric impregnation vessel and a method by which the total alkali charge to the chips content passing through the impregnation vessel is split into two steps such that the alkali is charged to the impregnation vessel and the chips content therein at two different levels.
  • the advantages provided by the present invention are best exploited when the alkali content in the spent liquor withdrawn by a first withdrawal screen at an upper level is measured and compared with a target value for the alkali content, such that the amount of alkali charged via a first central pipe at the level of this first withdrawal screen can be adjusted, e.g. iteratively adjusted, and tuned until the target value is reached.
  • such measurements can be done on-line with sensors SI and S2, e.g. with the measurement apparatuses AM300TM and Kemotron, which both are based on conductivity measurements, and are marketed and sold by the company Valmet AB.
  • the sensors may be connected to a local control unit CPU or the mill control system DCS.
  • measurements of the alkali content in the liquor withdrawn by a first withdrawal screen can alternatively by made off-line in a laboratory, for example such that samples of withdrawn liquor extracted in positions XI and X2 are sent to a laboratory for analysis at a regular basis, e.g., daily or according to the normal shift frequency.
  • Fig. 2 also disclose and alternative liquor routing where the liquor withdrawn from first screen 3 is connected with a branch to the liquor withdrawn from the second screen 4, and the balancing of liquor flows may be controlled by pumps PI and P2. As PI is connected close to pipe 11 the bulk volume sent to recovery will be that from screen 3, while the bulk volume sent to the central pipe 9 will be that from screen 4.
  • Such connection with a branch enable temporary changes in withdrawal volumes from individual withdrawal screens, while keeping the total withdrawal volumes constant.
  • the invention provides a possibility to split the alkali charge (mainly in the form of white liquor) into two charges, which already provides significant advantages when it comes to, for example, the alkali losses to extraction and the overall alkali profile in the impregnation vessel.
  • an estimate of the amount of alkali charged at an upper level via a first central pipe can be estimated based on wood consumption as tested in laboratory, for example based on the chip retention time at the level of the upper withdrawal screen and the radial liquor flow from the center of the impregnation vessel to the wall thereof, while the rest of the alkali needed for the further impregnation of the chips content is charged via a second central pipe at lower level, i.e. at the level of a lower withdrawal screen.
  • the invention provides for an optimum use of alkaline liquor.
  • ImpBinTM systems has the supply of hot black liquor been given an alkali level that by margin would be sufficient to keep the pH in the first withdrawal above precipitation level, and the residual alkali level for the remaining impregnation below the second withdrawal also above a minimum level.
  • the entire cooking system typically has the entire cooking system been designed such that the positioning of a withdrawal screen in the cooking zone assures a certain residual alkali level that satisfy the requirements, and with no additional charging of alkaline liquors into the hot black liquor or the recirculated impregnation liquor in the lower circulation. Adding additional alkaline liquors to impregnation has often only been considered when the digester system in steady state operation clog up the first withdrawal screen or if the impregnation of the chips does not reach the target.

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Abstract

L'invention concerne un procédé et une cuve d'imprégnation, dans lesquels le volume en vrac de liqueur d'imprégnation ajoutée se présente sous la forme de liqueur noire chaude ayant une teneur en alcali résiduel. La liqueur noire chaude est ajoutée dans un tuyau central supérieur acheminant la liqueur noire chaude en tant que liqueur d'imprégnation et une vapeur d'extinction pour chasser l'air du matériau de cellulose réduit. Pendant ce premier traitement à la vapeur, l'acidité de bois libérée par le matériau et la liqueur d'imprégnation usée ayant une teneur en acidité de bois sont retirées d'un tamis de retrait supérieur pour être récupérées, un tamis de retrait inférieur fait recirculer la liqueur d'imprégnation restante vers un second tuyau central inférieur afin d'égaliser la teneur en alcali bien avant le temps de rétention restant dans la cuve d'imprégnation. Selon l'invention, un alcali supplémentaire est ajouté à la liqueur noire chaude et la liqueur d'imprégnation en recirculation, respectivement, selon le niveau d'alcali établi dans la liqueur retirée du tamis de retrait supérieur et le niveau d'alcali établi en dessous du tamis de retrait inférieur.
PCT/SE2017/050555 2016-05-27 2017-05-23 Charge d'alcali double pour imprégnation de copeau WO2017204736A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN201780031762.XA CN109312537A (zh) 2016-05-27 2017-05-23 用于料片浸渍的双重碱加料
BR112018070795A BR112018070795A2 (pt) 2016-05-27 2017-05-23 método para a impregnação de lascas durante a fabricação de polpa química, e, vaso de impregnação atmosférico
EP17803173.8A EP3464714A4 (fr) 2016-05-27 2017-05-23 Charge d'alcali double pour imprégnation de copeau
US16/302,851 US20190194867A1 (en) 2016-05-27 2017-05-23 Double alkali charging for chip impregnation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE1650742-8 2016-05-27
SE1650742 2016-05-27

Publications (1)

Publication Number Publication Date
WO2017204736A1 true WO2017204736A1 (fr) 2017-11-30

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PCT/SE2017/050555 WO2017204736A1 (fr) 2016-05-27 2017-05-23 Charge d'alcali double pour imprégnation de copeau

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US (1) US20190194867A1 (fr)
EP (1) EP3464714A4 (fr)
CN (1) CN109312537A (fr)
BR (1) BR112018070795A2 (fr)
WO (1) WO2017204736A1 (fr)

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WO2020104730A1 (fr) * 2018-11-22 2020-05-28 Andritz Oy Agencement pour l'installation de capteurs de surveillance d'un récipient de traitement pour matériau lignocelllulosique

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Publication number Priority date Publication date Assignee Title
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EP3464714A4 (fr) 2019-12-25
BR112018070795A2 (pt) 2019-02-05
US20190194867A1 (en) 2019-06-27
EP3464714A1 (fr) 2019-04-10
CN109312537A (zh) 2019-02-05

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