EP2992136A1 - Procédé et système pour le lavage de pâte cellulosique - Google Patents

Procédé et système pour le lavage de pâte cellulosique

Info

Publication number
EP2992136A1
EP2992136A1 EP14792129.0A EP14792129A EP2992136A1 EP 2992136 A1 EP2992136 A1 EP 2992136A1 EP 14792129 A EP14792129 A EP 14792129A EP 2992136 A1 EP2992136 A1 EP 2992136A1
Authority
EP
European Patent Office
Prior art keywords
washing
pulp
washing operation
processing surface
washing apparatus
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14792129.0A
Other languages
German (de)
English (en)
Other versions
EP2992136A4 (fr
Inventor
Anders HEDBLOM
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valmet Oy
Valmet AB
Original Assignee
Valmet Oy
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 Oy, Valmet AB filed Critical Valmet Oy
Publication of EP2992136A1 publication Critical patent/EP2992136A1/fr
Publication of EP2992136A4 publication Critical patent/EP2992136A4/fr
Withdrawn legal-status Critical Current

Links

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
    • 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
    • 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
    • D21C9/06—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents in filters ; Washing of concentrated pulp, e.g. pulp mats, on filtering surfaces
    • 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
    • D21C9/18—De-watering; Elimination of cooking or pulp-treating liquors from the pulp

Definitions

  • the present invention relates to treatment of cellulose pulp and more specifically to a method and a system for washing of cellulose pulp.
  • Pulp washing is a key operation in the treatment of cellulose pulp. Washing is performed at several positions in the pulping line, such as after the digester, in the screening department, and following oxygen reactors and bleaching towers, in order to remove liquor (with chemicals, dirt, dissolved substances, etc) from the pulp.
  • a well-known washing apparatus is a twin-roll press of the general type disclosed in US Patent 3,980,518, for example.
  • a twin-roll press has two counter-rotating rolls with perforated outer surfaces. The incoming pulp is distributed lengthwise onto the respective roll. A web of pulp is formed on the respective roll and transported in the direction of rotation in a vat partially surrounding the rolls, until the so-called press nip between the rolls.
  • the twin-roll press uses the washing principles of displacement, where dirty liquid (liquor) in the pulp is replaced by cleaner wash liquid added to the vat, and pressing, where dirty liquid is pressed/squeezed out from the pulp, in particular at the press nip.
  • a washing apparatus like the twin-roll press for example, is associated with a limited performance. Sometimes two or more wash presses are arranged in series one after another in order to achieve a desired washing efficiency. However, washing apparatuses such as twin-roll presses are expensive and space-requiring machines. They also consume a lot of energy. Besides, introducing additional machines in the pulp mill is generally problematic.
  • An object of the invention is to provide an improved method for washing of cellulose pulp. Another object is to provide an efficient method for washing cellulose pulp, which is comparatively inexpensive and/or requires little space.
  • the present invention is based on the recognition that it is possible to achieve efficient washing by using one and the same washing apparatus for two (or more) non-simultaneous washing operations.
  • the washing operations are separated in time by means of an intermediate pulp storage, such that pulp is washed batch-wise in the washing apparatus, and stored in the intermediate pulp storage between the washing operations.
  • a method for washing of cellulose pulp comprising washing, in a first washing operation, the pulp for a first predetermined period of time using a washing apparatus with a movable permeable processing surface. Filtrate from the pulp passes through the processing surface as the pulp is transported together with the processing surface. The pulp washed in the first washing operation is received by an intermediate pulp storage connected to the washing apparatus and stored in the intermediate pulp storage. The pulp is then washed, in a second washing operation, for a second predetermined period of time using the washing apparatus, the pulp being received from the intermediate pulp storage and applied onto the processing surface of the washing apparatus, such that the pulp is washed again in the same washing space of the washing apparatus.
  • the washing and storing is preferably repeated such that the pulp is washed batch-wise using the intermediate pulp storage, each batch of pulp being washed in two separate washing operations, which occur in the same washing space of the same washing apparatus but are separate in time.
  • a system for washing cellulose pulp is provided.
  • a general view within the pulping industry is that one should always strive for a continuous pulp flow and stable conditions in the pulping line.
  • the invention proposes to interrupt the pulp flow and perform loop washing in a batch-wise manner. Surprisingly, the washing performance/result becomes satisfactory despite the discontinuous flow through the washing apparatus.
  • Two (or more) conventional washing apparatuses can be replaced with a larger washing apparatus and an intermediate pulp storage arranged according to the invention.
  • the washing apparatuses replaced may be arranged next to each other in the pulping line, or be from different parts of the pulping line associated with similar process conditions.
  • the invention also means that demands for increased washing efficiency can be handled without the need for an additional washing apparatus.
  • the proposed solution is comparatively inexpensive and consumes less energy than conventional washing with presses in series. It also requires less space in the pulp mill.
  • Fig. 1 is a schematic block diagram of a system for washing cellulose pulp according to an exemplifying embodiment of the invention
  • Fig. 2 is a schematic block diagram of a system for washing cellulose pulp according to another exemplifying embodiment of the invention
  • Fig. 3 is a schematic block diagram of a system for washing cellulose pulp according to still another exemplifying embodiment of the invention
  • Fig. 4 is a schematic cross-sectional view illustrating a twin-roll press which is used in an exemplifying embodiment of the invention.
  • Fig. 5 is a flow chart of a method for washing cellulose pulp according to an exemplifying embodiment of the invention.
  • Fig. 1 is a schematic block diagram of a system for washing cellulose pulp according to an exemplifying embodiment of the invention.
  • the illustrated system 100 includes a washing apparatus 10, an intermediate pulp storage 20, a first and a second process vessel 30, 40 connected to the washing apparatus 10, and a first and a second filtrate tank 51, 52.
  • a washing apparatus 10 When the system is in operation, there is a first washing operation I, where pulp from the first process vessel 30 is washed in the washing apparatus 10 during transport together with a movable permeable processing surface 11 (e.g. a rotatable surface, such as the perforated outer surface of a press roll 15), and then led to the intermediate pulp storage 20.
  • a subsequent second washing operation II pulp from the intermediate pulp storage 20 is washed in the same washing space of the same washing apparatus 10 as in the first washing operation I, and then output to the second process vessel 40.
  • filtrate passing through the permeable processing surface 11 is collected into the first filtrate tank 51.
  • filtrate passing through the permeable processing surface 11 is collected into the second filtrate tank 52.
  • filtrate from the second operation II is returned to the first washing operation I and used as washing liquid. Filtrate may also be used for dilution of the pulp.
  • the pulp is preferably washed batch-wise using the intermediate pulp storage 20, such that each batch of pulp is washed in two separate washing operations I, II, which occur in the same washing space of the same washing apparatus 10 but are separate in time.
  • Washing space here refers to a space within the washing apparatus 10 where the pulp is transported on the processing surface 11 and washed or dewatered.
  • the washing space associated with washing operation I is the space within the washing apparatus 10 where the pulp is transported on the processing surface 11 during washing operation I
  • the washing space associated with washing operation II is where the pulp is transported on the processing surface 11 during washing operation II.
  • the washing space of washing operation I is the same as the washing space of washing operation II.
  • Washing space refers to a stationary space within the washing apparatus 10.
  • the processing surface 11, i.e. the permeable surface onto which pulp is applied, is identical in the first and second washing operation I, II.
  • the full axial length of the washing apparatus is used.
  • substantially the entire length of the press rolls 15 is used in each washing operation I, II.
  • the input area of the washing apparatus 10, where the pulp is distributed onto the processing surface 11, is substantially the same in washing operation I and II.
  • the output area of the washing apparatus 10, i.e. where the pulp is withdrawn from the processing surface 11, is substantially the same in washing operation I and II.
  • the input and output area, respectively, are stationary areas within the washing apparatus 10 and form the beginning and end of the washing space.
  • the intermediate pulp storage 20 is typically a tank/vessel with a storage volume exceeding the volume of pulp produced in the respective washing operation I, II.
  • the intermediate pulp storage 20 is dimensioned for storing the pulp between washing operation I and II.
  • the intermediate pulp storage 20 may be a pure pulp storage/buffer or, alternatively, function also as a processing tank/vessel with chemical addition, temperature control, dilution, or other processing of the pulp. Examples include a medium consistency (MC) tank, a high consistency (HC) tank, an acid stage (A), and a bleaching tower/reactor, e.g.
  • D chlorine dioxide
  • O oxygen
  • P peroxide
  • Q chelating agent treatment
  • EO alkali-oxygen
  • EOP alkali- oxygen-peroxide
  • the intermediate pulp storage 20 is external to the washing apparatus 10, i.e. a separate physical unit.
  • the pulp thus leaves the washing apparatus 10 between the washing of washing operation I and II, respectively.
  • the intermediate pulp storage 20 comprises two or more parallel tanks.
  • the process vessels 30, 40 are vessels/tanks in the pulping process (i.e. the pulping line) outputting or receiving pulp washed in accordance with the invention.
  • Each process vessel 30, 40 may be a processing tower/reactor/tank or, alternatively, a pure pulp storage. Examples include a blow tank (BT), an MC/HC tank, an A stage, and a bleaching tower/reactor, e.g. D, O, P, Q, EO, EOP.
  • the intermediate pulp storage 20 serves as a pulp buffer alternating between a filling mode, during the first washing operation I, and an emptying mode, during the second washing operation II.
  • the first and second process vessel 30, 40 are also arranged to alternate between an emptying mode and a filling mode, but the emptying mode is associated with the first washing operation I, and the filling mode is associated with the second washing operation II.
  • emptying mode does not necessarily mean that the vessel is completely empty after the washing operation.
  • process vessels 30, 40 there is often a minimum level of pulp required in the vessel for the overall process to run smoothly.
  • there is a flow of pulp into the first process vessel 30 also during emptying mode but the outgoing flow is larger.
  • valves 5 indicate that the flows of the first and second washing operation I, II are not continuous.
  • a pump 21 is also shown, arranged to output pulp from the intermediate pulp storage 20 during the second washing operation II.
  • the pulp can be diluted by an appropriate dilution means so that it can be pumped from the intermediate pulp storage 20.
  • the system of the invention may be implemented using conventional equipment, such as piping, valves, pumps, dilution screws etc. Details, such as where valves are needed and not, are routine measures for which no inventive skill is needed.
  • the first washing operation I takes place during a first predetermined period of time
  • the second washing operation II takes place during a second predetermined period of time.
  • These predetermined periods of time do not have to be fixed time intervals but could also, for example, be determined as the time it takes for a particular volume of pulp to pass through the washing apparatus 10.
  • a possible approach would be to determine the period of time based on at least one process parameter, e.g. such that the level of pulp in a particular process tank does not go beyond a maximum or minimum value.
  • the period of time could be determined based on process parameters indicating the pulp quality, degree of bleaching, system performance etc.
  • Various control strategies are possible.
  • the process conditions should preferably be about the same or similar in the first and second washing operation.
  • the processing should preferably be of a similar kind as the processing of the pulp in the process vessel 30 before the first washing operation I.
  • a high degree of chlorides means that the parts of the washing apparatus that come into contact with the pulp have to be of a resistant, expensive material.
  • Example combinations of intermediate pulp storages 20 and first and second process vessels 30, 40 in accordance with the invention are provided in Table 1.
  • Dl and D2 are chlorine dioxide stages, PI and P2 are peroxide stages, etc.
  • HC tanks may, depending on the application, be used as storage tanks instead of MC tanks.
  • Example 2 the first process vessel 30, the intermediate pulp storage 20, and the second process vessel 40 are pure storage tanks. In the other examples acid or bleaching chemicals are added to at least one of the first process vessel 30, the intermediate pulp storage 20, and the second process vessel 40.
  • two conventional washing machines each with production volume V
  • V may be replaced by a large washing machine with production volume V+V operated according to the invention.
  • the invention requires piping, valves etc. and in some cases an additional tank/vessel with an associated pump. Nevertheless, the proposed system leads to reduced costs, since a larger washing machine is much cheaper per produced volume of pulp than two smaller washing machines. Another important advantage is that less energy is consumed by the system of the invention than by conventional washing systems.
  • the first and second washing operation I, II is each run during a period of time of 0.03 to 2 hours.
  • a short washing cycle would be preferred or else the volume of pulp in the buffer(s) may be difficult to handle.
  • the filtrate handling is also facilitated by a short washing cycle.
  • a period of time of about 3-5 min per washing operation may for example be used.
  • the washing cycle cannot be too long, or else the retention time of the pulp will vary too much within the reactor.
  • a period of time of about 10- 30 min per washing operation may for example be used. Therefore, a preferred period of time for each washing operation is in the range of about 3 to 30 min.
  • the amount of washing liquid (not shown in drawings) added to the pulp on the processing surface 11 may be adapted to the respective washing operation I, II.
  • Another parameter, which may be adjusted, is the rotation speed of the movable permeable processing surface 11.
  • Another parameter, which may be adapted to the respective washing operation I, II is the amount of added dilution liquid, diluting the pulp to pumping consistency after the washing in the washing apparatus 10. Adapting these parameters (changing settings or intervals) may e.g. be appropriate if the pulp consistency is different in washing operation I and II.
  • washing apparatus 10 is illustrated as a twin-roll press, this is only an example.
  • Another washing apparatus such as a diffuser, a filter, a drum washer (e.g. drum displacement washer), or a different type of press (e.g. a wire press), may also be used in accordance with the invention.
  • the movable permeable processing surface 11 may comprise a perforated press roll or drum surface, a wire, or a screen of a diffuser.
  • Fig. 2 illustrates another exemplifying system of the invention with three washing operations I, II, III in the same washing apparatus.
  • This system 200 includes a second intermediate pulp storage 60 in addition to the intermediate pulp storage 20 of Fig. 1.
  • the second intermediate pulp storage 60 is connected to the washing apparatus 10.
  • the washed pulp is led to the second intermediate pulp storage 60, and in a third washing operation III, the pulp is for a third time washed on the processing surface 11 in the same washing space of the washing apparatus 10.
  • the third washing operation III is associated with a third predetermined period of time. What is said about the first and second predetermined periods of time above may be applied also on the third period of time.
  • the process conditions, such as pH and temperature, should preferably be about the same or similar in all three washing operations I, II, III.
  • filtrate tank 51, 52, 53 for each washing operation and filtrate may be used as washing liquid in a preceding washing operation.
  • the washing principles of Fig. 2 may be used to replace three conventional washing apparatuses with one single, larger washing apparatus. Basically, three washing machines with production volume V each, may be replaced by a single washing machine with production volume V+V+V, which means that the overall benefit is even larger than for the case with only two washing operations I, II.
  • Fig. 3 illustrates another exemplifying system 300 of the invention with two washing operations I, II in the same washing apparatus 10.
  • the washing apparatus 10 is connected to the intermediate pulp storage 20 via additional processing equipment 70, such that there is additional processing, such as bleaching, between the first washing in the washing apparatus 10 and the storing in the intermediate pulp storage 20.
  • the additional processing equipment 70 may for example include a bleaching tower with an associated washer and other associated equipment such as a pump, a dilution screw, etc. There is in such a case a pulp flow through the washer of the additional processing equipment 70 (i.e. the washer arranged after the bleaching tower) during both washing operations I, II.
  • the bleaching tower of the additional processing equipment 70 serves as an additional pulp buffer, arranged to alternate between a filling mode, during the first washing operation I, and an emptying mode, during the second washing operation II.
  • a washing apparatus may be shared between process stages, e.g. bleaching stages, that do not follow directly after each other in the pulping line.
  • the process conditions should preferably be about the same or similar in the first and second washing operation I, II.
  • Example 7 relates to a pulping line including the bleaching sequence DO EOP Dl D2 (generally with washing after each bleaching tower).
  • the DO and Dl stages share the same washing apparatus, operated according to the principles of the invention. In other words, washing is performed in one and the same washing apparatus 10 between the DO and EOP towers and between the Dl and D2 towers, respectively. Sharing a washing apparatus between two D- stages like in Example 7 has the advantage that the process conditions of the two washing operations I, II in the washing apparatus are very similar (same pH, etc.).
  • Example 8 relates to a pulping line including the bleaching sequence MC DO EO Dl (generally with washing after each pulp tower).
  • the MC tower may, depending on the application, be replaced by a HC tower.
  • the MC/HC tower and EO share the same washing apparatus, operated according to the principles of the invention.
  • existing vessels/tanks of the bleaching stages may be used and there is no need for introducing a new tank/vessel as pulp buffer.
  • Fig. 2 and 3 may be combined to a system with three washing operations I, II, III where the first and second washing operation I, II and/or the second and third washing operation II, III need not be performed directly after each other.
  • three washing machines from different parts of the pulping line and associated with production volume V each may in this way be replaced by a single washing machine with production volume V+V+V.
  • Fig. 4 is a schematic cross-sectional view of an example washing apparatus, a twin-roll press 10, of a preferred system according to the invention.
  • the twin roll press 10 comprises two cooperating cylindrical press rolls/drums 15.
  • the two press rolls 15 are arranged to rotate in opposite directions Dl during operation and each has a permeable outer surface 11, more specifically a perforated metal sheet.
  • the press rolls 15 are partially enclosed by a vat 16 (also known as trough) formed by guide surfaces, arranged at a distance from the perforated outer surface 11 of the respective press roll 15 so as to partially enclose the press roll in the circumferential direction.
  • vat 16 also known as trough
  • a pulp distribution device 12 is associated with each press roll 15.
  • the pulp distribution device 12 is arranged at the upper portion of the press roll 15 for distribution of pulp onto the perforated roll surface 11. It comprises an elongated housing 18, extending lengthwise along a substantial portion of the press roll 15, and is connected to the vat 16. During operation, pulp enters the pulp distribution device 12 via its inlet, which for example can be arranged at the middle of the twin-roll press 10 as seen in the longitudinal direction.
  • the pulp is distributed in the longitudinal direction and output through the outlet 13 to form a pulp web on the perforated roll surface 11.
  • the pulp web is transported, guided by the vat 16, in the direction of rotation Dl to be pressed in a nip (also known as pinch) 17 where the distance between the press rolls 15 is smallest.
  • the press rolls 15 may comprise axial filtrate channels (not shown) which receive the filtrate that passes through the perforated roll surface 11, and transport it towards the ends of the press rolls 15, where it is output. Washing liquid may e.g. be supplied to the pulp web in the vat 16.
  • the pulp is output by means of a discharge screw 19.
  • the washing space is defined by the perforated roll surface 11 and the vat 16, and basically encloses the portion of the perforated roll surface 11 where there, during operation, is a pulp web.
  • the washing space is thus stationary, although the perforated roll surface 11 is moving.
  • Fig. 4 two press rolls 15 are arranged next to each other, with the rotation centers in the same horizontal plane.
  • the invention is also suitable for washing and/or dewatering apparatuses where, for example, the rolls are differently arranged, or only one perforated roll is used, as well as for another apparatus where pulp is dewatered on a movable permeable surface.
  • One example system of the invention includes a twin roll press 10 with a non-converging vat 16, i.e. a vat which is parallel or diverging from the position where pulp is applied onto the press roll 15 until the press nip 17.
  • the non-converging vat 16 makes the system of the invention less sensitive to varying process conditions, such as varying pulp consistency and flow.
  • Another advantageous system of the invention includes a twin roll press 10 with means for adjustment of the distance between the press rolls 15 in response to varying operating conditions of the respective washing operations I, II, III.
  • the press nip 17 is preferably automatically varied during operation, between the washing operations I, II, III and preferably also during each washing operation. By means of nip control, the washing in the twin-roll press 10 becomes more efficient and the press 10 becomes less sensitive to varying load.
  • Still another advantageous system of the invention includes a twin roll press 10, the press rolls 15 of which have a diameter in the range of 0.8-3m, preferably 1.5-3m and a length in the range of 1.2-1 lm, preferably 4-1 lm.
  • a twin roll press 10 the production volume can be maintained although the press is arranged to handle two different washing operations.
  • Two conventional presses 10, each with production volume V may be replaced by a large press with production volume V+V operated according to the invention.
  • Still another advantageous system of the invention includes a washing apparatus having an open pulp distribution device, such as the pulp distribution device 12 illustrated in Fig. 4.
  • the pulp distribution device 12 comprises a rotatable distribution means 14 arranged to distribute pulp onto the movable permeable processing surface 11 and an outlet 13 which opens towards the pulp web, which, during operation, is formed on the permeable processing surface 11.
  • the outlet 13 has a length that corresponds to the width of the pulp web and the rotatable distribution means 14 is arranged to distribute the pulp along essentially the entire length of the outlet 13. There are no flow-restricting elements between the rotatable distribution means 14 and the permeable processing surface 11 in Fig. 4.
  • the outlet 13 of an open pulp distribution device 12 is open in the sense that no wall or other essential flow-restricting element is arranged in the outlet opening.
  • the open outlet 13 provides for a free flow of pulp from the pulp distribution device 12 towards the permeable processing surface 11.
  • the open pulp distribution device 12 can with advantage be of the type specified in Swedish patent SE 532 366, in particular with regard to the position of the rotatable distribution means 14. Such a device provides both distribution and forming of the pulp onto the press roll 15.
  • the open design of the pulp distribution device 12 makes the system of the invention capable of handling varying process conditions, such as varying pulp consistency and flow.
  • An open pulp distribution device 12 can be used in a twin roll press 10 but it may also be used to apply pulp onto the movable permeable processing surface 11 of another washing apparatus 10 operated according to the invention.
  • Fig. 5 is a flow chart of a method for washing cellulose pulp according to an exemplifying embodiment of the invention.
  • step SI pulp is washed in a first washing operation I using a washing apparatus 10 with a movable permeable processing surface 11.
  • the input consistency of the pulp is preferably in the range of 2-13%.
  • step S2 Chemicals may be added to the pulp in the intermediate pulp storage 20.
  • step S3 asks if the washing operation I is completed, i.e. if a predetermined condition determining the time of the washing operation I is fulfilled. If no, the process returns to step S I .
  • step S4 the settings of the washing apparatus 10, or of its associated equipment such as valves, dilution means, etc., may in step S4 (optional) be adjusted to suit the next washing operation.
  • the amount of washing liquid may for example be changed.
  • step S5 stored pulp is washed in a second washing operation II using the same washing apparatus 10 with the movable permeable processing surface 11.
  • the input consistency of the pulp is preferably in the range of 2-13%.
  • step S6 asks if the washing operation II is completed. If no, the process returns to step S5. If yes, the settings of the washing apparatus 10 may in step S7 (optional) be adjusted to suit the next washing operation. The process then returns to step SI .
  • the washing and storing steps SI, S2, S5 are preferably repeated such that the pulp is washed batch-wise using the intermediate pulp storage 20, each batch of pulp being washed in two separate washing operations I, II, which occur in the same washing space of the same washing apparatus 10 but are separate in time.
  • step S4 may for example comprise adjusting at least one parameter of: a flow of added washing liquid, a rotation speed, a flow of added dilution liquid, and a distance between press rolls 15.
  • the invention is not restricted to the illustrated embodiments, but covers also equivalents to the disclosed features and may be varied within the scope of the claims.

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

Abstract

L'invention porte sur un procédé et un système pour le lavage de pâte cellulosique. La pâte est lavée deux fois dans le même espace de lavage d'un appareil de lavage (10) doté d'une surface de traitement perméable amovible (11), le filtrat issue de la pâte passe à travers la surface de traitement alors que la pâte est transportée avec la surface de traitement. Il y a un stockage de pâte intermédiaire (20) raccordé à l'appareil de lavage (10) et conçu pour stocker la pâte entre les deux opérations de lavage (I, II).
EP14792129.0A 2013-05-03 2014-04-25 Procédé et système pour le lavage de pâte cellulosique Withdrawn EP2992136A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE1300319A SE537925C2 (sv) 2013-05-03 2013-05-03 Metod och system för tvättning av cellulosamassa
PCT/SE2014/050510 WO2014178780A1 (fr) 2013-05-03 2014-04-25 Procédé et système pour le lavage de pâte cellulosique

Publications (2)

Publication Number Publication Date
EP2992136A1 true EP2992136A1 (fr) 2016-03-09
EP2992136A4 EP2992136A4 (fr) 2016-12-21

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP14792129.0A Withdrawn EP2992136A4 (fr) 2013-05-03 2014-04-25 Procédé et système pour le lavage de pâte cellulosique

Country Status (4)

Country Link
EP (1) EP2992136A4 (fr)
CN (1) CN105189859A (fr)
SE (1) SE537925C2 (fr)
WO (1) WO2014178780A1 (fr)

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FI83841C (fi) * 1989-04-07 1991-09-10 Salomans Oy Foerfarande foer kontinuerligt utbyte av vaetskan i en suspension av ett fibroest eller finkornigt material.
US5275024A (en) * 1992-05-04 1994-01-04 The Black Clawson Company Paper pulp washing
US6006554A (en) * 1998-06-03 1999-12-28 Beloit Technologies, Inc. Two stage counter current drum washer
FI122775B (fi) * 2004-09-07 2012-06-29 Andritz Oy Laite ja menetelmä massan käsittelemiseksi
FI20041518A (fi) * 2004-11-25 2006-05-26 Andritz Oy Menetelmä ja laite meesan käsittelemiseksi
SE0602268L (sv) * 2006-10-27 2008-04-15 Metso Paper Inc Tvättpress innefattande separation av filtrat
WO2008147311A1 (fr) * 2007-05-25 2008-12-04 Metso Paper, Inc. Système de lavage et d'essorage de la pâte à papier cellulosique

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Publication number Publication date
WO2014178780A1 (fr) 2014-11-06
SE537925C2 (sv) 2015-11-24
SE1300319A1 (sv) 2014-11-04
CN105189859A (zh) 2015-12-23
EP2992136A4 (fr) 2016-12-21

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