This application is a U.S. national stage application of International App. No. PCT/FI2010/050194, filed Mar. 12, 2010, the disclosure of which is incorporated by reference herein, and claims priority on Finnish App. No. 20095283, filed Mar. 18, 2009, the disclosure of which is incorporated by reference herein.
Not applicable.
The invention relates to a refining surface of a refiner for a refiner intended for defibrating lignocellulose-containing material, which refining surface has a feed edge directed in the direction of the feed flow of the material to be refined and a discharge edge directed in the direction of the discharge flow of the refined material and which refining surface comprises at least one first blade bar and at least one second blade bar, between which there is a blade groove, the first and the second blade bars having a first end directed in the direction of the feed edge of the refining surface and a second end directed in the direction of the discharge edge of the refining surface; and that the refining surface comprises at least one third blade bar having a first end directed in the direction of the feed edge of the refining surface, and a second end directed in the direction of the discharge edge of the refining surface; and that the first end of the third blade bar has a guide surface rising from the direction of the feed edge of the refining surface in the direction of the discharge edge of the refining surface for guiding the lignocellulose-containing material to the upper surface of the third blade bar, the guide surface having a first end directed in the direction of the feed edge of the refining surface and a second end directed in the direction of the discharge edge of the refining surface.
Further, the invention relates to a blade segment of a refining surface for a refiner intended for defibrating lignocellulose-containing material, which blade segment is arrangeable to form a part of the refining surface of the refiner and which blade segment has a refining surface of the blade segment, the refining surface having a feed edge directed in the direction of the feed flow of the material to be refined and a discharge edge directed in the direction of the discharge flow of the refined material, and the refining surface of the blade segment comprising at least one first blade bar and at least one second blade bar, between which there is a blade groove, the first and the second blade bar having a first end directed in the direction of the feed edge of the refining surface and a second end directed in the direction of the discharge edge of the refining surface; and that the refining surface comprises at least one third blade bar having a first end directed in the direction of the feed edge of the refining surface and a second end directed in the direction of the discharge edge of the refining surface; and that the first end of the third blade bar has a guide surface rising from the direction of the feed edge of the refining surface in the direction of the discharge edge of the refining surface for guiding the lignocellulose-containing material to the upper surface of the third blade bar, the guide surface having a first end directed in the direction of the feed edge of the refining surface and a second end directed in the direction of the discharge edge of the refining surface.
Further, the invention relates to a refiner for defibrating lignocellulose-containing material.
Refiners used for manufacturing mechanical pulp typically comprise two or more refiner elements positioned oppositely and rotating relative to each other. The fixed, i.e. stationary, refiner element is called the stator of the refiner, the rotating or rotatable refiner element being called the rotor of the refiner. In disc refiners, the refiner elements are disc-like, and in cone refiners, the refiner elements are conical. In addition to disc refiners and cone refiners, there are also what are called disc-cone refiners, where disc-like refiner elements come first in the flow direction of the material to be defibrated, and after them the material to be defibrated is refined further between conical refiner elements. Furthermore, there are also cylindrical refiners, where both the stator and the rotor of the refiner are cylindrical refiner elements. The refining surfaces of the refiner elements are formed by blade bars, i.e. bars, and blade grooves, i.e. grooves, between them. The task of the blade bars is to defibrate the lignocellulosic material, and the task of the blade grooves is to transport both material to be defibrated and material already defibrated on the refining surface. In disc refiners, which represent the most common refiner type, the material to be refined is usually fed through an opening in the middle of the stator, i.e. on the inner periphery of the refining surface of the stator, to the space between the refining surfaces of the discs, i.e. to a blade gap. The refined material is discharged from the blade gap, from the outer periphery of the refining surfaces of the refiner discs, to be fed onwards in the pulp manufacturing process. The refining surfaces of the refiner discs may be either surfaces formed directly on the refiner discs, or they may be formed as separate blade segments positioned adjacent to each other in such a way that each blade segment forms a part of a continuous refining surface.
Usually, dams connecting two adjacent blade bars to each other are positioned at the bottom of the blade grooves of the refining surfaces of both the stator and the rotor of the refiner. The task of the dams is to guide material to be refined and material already refined to the space between the blade bars of opposite refining surfaces to be further refined. Since the dams guide the material to be refined to the space between opposite blade bars, refining the material can be promoted thanks to the dams. Simultaneously, however, the dams cause the steam flow taking the material to be refined onwards in the blade grooves to decrease, and prevent passage of the material to be refined and the material already refined on the refining surface by restricting the cross-sectional flow area of the blade grooves. This, in turn, leads to blockages on the refining surface, which then results in a decrease in the production capacity of the refiner, non-uniformity of the quality of the refined material and an increase in the energy consumed for the refining.
An object of this invention is to provide a refining surface of a novel type for a refiner.
The refining surface according to the invention is characterized in that said guide surface is arranged, in the direction of travel of the first blade bar and the second blade bar, at least partly between the first blade bar and the second blade bar, between the first blade bar and an imaginary extension of the second blade bar, between an imaginary extension of the first blade bar and the second blade bar, or between imaginary extensions of both the first blade bar and the second blade bar; and that a first side edge and a second side edge of the third blade bar are, at the same time, in contact with side edges of the first blade bar and the second blade bar, with the side edge of the first blade bar and an imaginary extension of the side edge of the second blade bar, with an imaginary extension of the side edge of the first blade bar and the side edge of the second blade bar, or with the imaginary extensions of the side edges of both the first blade bar and the second blade bar.
The blade segment according to the invention is characterized in that said guide surface is arranged, in the direction of travel of the first blade bar and the second blade bar, at least partly between the first blade bar and the second blade bar, between the first blade bar and an imaginary extension of the second blade bar, between an imaginary extension of the first blade bar and the second blade bar, or between the imaginary extensions of both the first blade bar and the second blade bar; and that a first side edge and a second side edge of the third blade bar are, at the same time, in contact with side edges of the first blade bar and the second blade bar, with the side edge of the first blade bar and an imaginary extension of the side edge of the second blade bar, with an imaginary extension of the side edge of the first blade bar and the side edge of the second blade bar, or with the imaginary extensions of the side edges of both the first blade bar and the second blade bar.
The refining surface of a refiner for defibrating lignocellulose-containing material comprises a feed edge directed in the direction of the feed flow of the material to be refined, and a discharge edge directed in the direction of the discharge flow of the refined material. The refining surface further comprises at least one first blade bar and at least one second blade bar, between which there is a blade groove, the first and the second blade bar comprising a first end directed in the direction of the feed edge of the refining surface, and a second end directed in the direction of the discharge edge of the refining surface. The refining surface further comprises at least one third blade bar having a first end directed in the direction of the feed edge of the refining surface and a second end directed in the direction of the discharge edge of the refining surface, the first end of the third blade bar having a guide surface rising from the direction of the feed edge of the refining surface towards the direction of the discharge edge of the refining surface for guiding lignocellulose-containing material to the upper surface of the third blade bar, which guide surface has a first end directed in the direction of the feed edge of the refining surface and a second end directed in the direction of the discharge edge of the refining surface. Said guide surface is further arranged, in the direction of travel of the first blade bar and the second blade bar, at least partly between the first blade bar and the second blade bar, between the first blade bar and an imaginary extension of the second blade bar, between an imaginary extension of the first blade bar and the second blade bar, or between imaginary extensions of both the first blade bar and the second blade bar. Further, a first side edge and a second side edge of the third blade bar are, at the same time, in contact with the side edges of the first blade bar and the second blade bar, with the side edge of the first blade bar and an imaginary extension of the side edge of the second blade bar, with an imaginary extension of the side edge of the first blade bar and the side edge of the second blade bar, or with imaginary extensions of both the first blade bar and the second blade bar.
Positioning the blade bars according to the above allows such a refining surface to be provided which has no actual dams but in which the material under refining can be guided by the effect of the guide surface to the blade gap of the refiner, while the steam generated in the refining and travelling in the blade grooves and pushing, at the same time, the material under refining onwards is still capable of travelling partly past the guide surface from the blade groove between the first and the second blade bar into the blade grooves adjacent to the third blade bar. Thus, the flow of both the material to be refined and the steam is facilitated, whereby less energy goes to waste and blockages in the blade grooves are decreased.
Some embodiments of the invention are disclosed in greater detail in the attached drawings.
For the sake of clarity, the figures show some embodiments of the invention simplified. Similar parts are denoted with the same reference numerals in the figures.
The lignocellulose-containing material to be defibrated is fed via an opening 7 in the middle of the second refining surface 2 to the refiner mouth between the refining surfaces 1 and 2, where it is defibrated and refined. The lignocellulose-containing material to be defibrated may be fed to a refiner mouth also via openings in the second refining surface 2, not shown for the sake of clarity. The defibrated lingocellulose-containing material is discharged from the outer edge of the blade gap 10 between the refining surfaces 3 and 4 to the inside of a refiner chamber 8 and further out of the refiner chamber 8 along a discharge channel 9.
The lignocellulose-containing material to be defibrated is fed via an opening 7 in the middle of the second refining surface 2 into the conical refiner mouth between the refining surfaces 1 and 2, where it is defibrated and refined. The defibrated lignocellulose-containg material is discharged from the outer edge of the refiner mouth between the refiner elements 3 and 4 to the inside of the refiner chamber 8 and further out of the refiner chamber 8 along a discharge channel 9.
In addition to disc refiners and cone refiners, there are also what are called disc-cone refiners where disc-like refiner elements come first in the flow direction of the material to be defibrated, after which the material to be defibrated is further refined between conical refiner elements. Furthermore, there are also cylindrical refiners where both the stator and the rotor of the refiner are cylindrical refiner elements. The general structural and operating principle of the different refiners are known as such to a person skilled in the art, so they will not be described in more detail in this context.
The refining surface 16 of the blade segment 11 according to
The refining surface 16 according to
The new blade bar 14′″, i.e. the third blade bar 14′″, starting from between two adjacent blade bars, i.e. between the first blade bar 14′ and the second blade bar 14″, can be positioned relative to its guide surface 21 in many different ways in the direction of travel of the first blade bar 14′ and the second blade bar 14″. In the embodiment of
What is called “open staggering” of the blade bars 14, i.e. staggering where there is a slot 22 on both sides of the guide surface 21 of the third blade bar 14′″, as described above, can be used for instance when refining chips in inner refining surface zones, i.e. refining surface zones closer to the feed of the material to be refined. In this area, blade bars need not be densely positioned because the material to be refined is still in relatively large pieces. What is important, however, is to guarantee unrestricted flow of the material to be refined farther into the blade gap, which is promoted by open staggering as the structure facilitating the flow of steam.
Changing the staggering depth of the blade bars 14, i.e. how far the first end 14a of the third blade bar 14′″ extends to the space between the first blade bar 14′ and the second blade bar 14″, and the angle of elevation of the guide surface 21 at the first end 14a of the blade bar 14 allows the size of the slots 22 between the ends of the blade bars 14 and thus the steam flows on the refining surface 16 to be affected. The angle of elevation of the guide surface 21 relative to the upper surface 14c of the blade bar 14 may vary between 20 and 55 degrees, for example, preferably between 30 and 45 degrees. The smaller the angle of elevation of the guide surface 21 is, the larger part of the steam flow travelling in the blade groove moves into the blade grooves adjacent to the blade bar. In the portion on the side of the feed edge of the refining surface, a gentler angle of elevation can be used for the guide surface, and in the refining surface zones following it, i.e. in zones performing more intense refining, it is preferable to use a steeper angle of elevation of the guide surface. A gentle angle of elevation of the guide surface combined with closed or nearly closed staggering of the blade bars, which is described in the following, in zones that perform more intense refining takes too much volume and may lead to steam flowing problems.
Further, deviating from
In refiner applications where a lot of steam is generated in the blade gap 10 of the refiner, the first end 14a of the third blade bar 14′″ may be arranged relative to the second ends 14b of the first blade bar 14′ and the second blade bar 14″ in such a way that the slots 22 between the ends of the blade bars become relatively large, as a result of which the flow of steam past the guide surface 21 of the third blade bar 14′″ is boosted. Thus, the first end 21a of the guide surface 21 of the third blade bar 14′″ can be positioned, in the direction of travel of the first blade bar 14′ and the second blade bar 14″, at the point where the first blade bar 14′ and the second blade bar 14″ end or even at a point which is, in the direction of travel of the first blade bar 14′ and the second blade bar 14″, at a distance from the second ends 14b of the first 14′ and the second 14″ blade bar, whereby the third blade bar 14′″ is arranged between imaginary extensions of both the first blade bar 14′ and the second blade bar 14″ in the direction of travel of the first 14′ and the second blade bar 14″. Hence, the direction of travel of the first blade bar 14′ and the second blade bar 14″ means the direction of the tangent of the first blade bar 14′ and the second blade bar 14″ at the second end 14b of the first blade bar 14′ and the second blade bar 14″.
The embodiment according to
In such “oblique staggering”, it is possible to stagger the blade bars relative to each other also in such a way that the first end 21a of the guide surface 21 of the third blade bar 14′″ may be positioned, in the direction of travel of the first blade bar 14′ or the second blade bar 14″, at the point where the first blade bar 14′ or the second blade bar 14″ ends, or even at a point which is, in the direction of travel of the first blade bar 14′ or the second blade bar 14″, at a distance from the second end 14b of the first 14′ or the second 14″ blade bar, whereby the third blade bar is arranged, at least over part of its length, either between the first blade bar 14′ and an imaginary extension of the second blade bar 14″ or between an imaginary extension of the first blade bar 14′ and the second blade bar 14″ in the direction of travel of the first 14′ and the second blade bar 14″. Thus, the direction of travel of the first blade bar 14′ or of the second blade bar 14′ means the tangential direction of the first blade bar 14′ or the second blade bar 14″ at the second end 14b of the first blade bar 14′ or the second blade bar 14″.
When it is desirable to achieve the most efficient refining possible, that half of the third blade bar 14′″ where the slot 22 is smaller or where there is no slot 22 at all may be positioned, in the case of a rotating refining surface, i.e. the rotor of the refiner, in an opposite direction relative to the direction of rotation of the rotor, i.e. farther behind in the direction of rotation. In the case of a stationary refining surface, i.e. the stator of the refiner, that half of the third blade bar 14′″ where the slot 22 is smaller or where there is no slot 22 at all may be positioned in the same direction with the rotation direction of the rotor, i.e. on that side of the blade bar which is the last one to meet the rotor. Thus, that half of the guide surface 21 of the third blade bar 14′″ where the slot 22 is smaller or where there is no slot at all lifts material under refining more efficiently from the blade groove into the blade gap between the refining surfaces. Simultaneously, on that side of the guide surface 21 of the third blade bar 14′″ where the slot 22 is larger, the steam can flow more freely from one blade groove to another.
In the case of the refining surface of a stator, a phenomenon characteristic of stators, i.e. the back flow of steam in a given area on the refining surface of the stator, may be taken into account when arranging the blade bars relative to each other. This back flow of steam may be taken into account by staggering the blade bars relative to each other and setting the angle of elevation of the guide surface of the blade bar such that the steam cannot flow on the refining surface back from the slots between the blade bars but that it turns upwards thanks to a wall 14d at the second end 14b of the blade bar. Such a solution implemented on the refining surface of the stator makes it possible to further boost the refining.
Blade segments 11 may be used to form a part of the refining surface of the refiner in such a way that the feed edge 12 of the blade segment 11 corresponds to the feed edge of the whole refining surface and that the discharge edge 13 of the blade segment 11 corresponds to the discharge edge of the whole refining surface, whereby the blade bars 14 and the blade grooves 15, which are at the same distance from the feed edge 12 of the refining surface, belong to the same refining surface zone. However, the blade segments 11 may be used to form only a part of one refining surface zone of the refining surface, i.e. a part of the first 17, the second 18, the third 19 or the fourth 20 refining surface zone of the refining surface, shown in an exemplary manner in
In the figures, various embodiments are shown by using the refining surface of a blade segment as an example but all of the various embodiments may also be applied to a refining surface implemented as a continuous refining surface structure.
In some cases, features disclosed in the description may be used as such, irrespective of other features. On the other hand, features disclosed in the description may, if required, be combined to form various combinations.
The drawings and the related description are only intended to illustrate the idea of the invention. Details of the invention may vary within the scope of the claims.
The structures of the blade bars 14 shown in the figures are straight but the blade bars 14 could also have a curved longitudinal structure. Further, the blade bars may be arranged to be either pumping or feeding blade bars, i.e. blade bars promoting the passage of the material to be refined on the refining surface, or retaining blade bars, i.e. blade bars restricting the passage of the material to be refined on the refining surface, or a combination thereof.
A pumping blade bar means a blade bar which produces for a pulp particle to be refined both a speed component in the circumferential direction of the refining surface, i.e. in the direction of the perpendicular of the blade segment radius, and a speed component in the direction of the refining surface radius, directed from the feed edge of the refining surface towards the discharge edge of the refining surface. A retaining blade bar means a blade bar which produces for a pulp particle to be refined both a speed component in the circumferential direction of the refining surface, i.e. in the direction of the perpendicular of the blade segment radius, and a speed component in the direction of the refining surface radius, directed from the discharge edge of the refining surface towards the feed edge of the refining surface. For example, when the blade surface of
The blade segment of
With selection of the blade bar angles it is possible to have an influence on how much energy the blade arrangement consumes and what the change in the refining degree achieved with the refining is like. An intensely pumping blade solution leads to a short retention time of the material in the blade gap, whereby the refining consumes little energy. Thus, uniform refining treatment is achieved for the material to be refined but the change in the refining degree remains relatively small. With a blade solution that pumps less, the material remains longer in the blade gap, whereby the energy consumption of the refining is greater, and a greater change in the refining degree is achieved. If an intensely retaining blade solution is used, the retention time of the refining is long, resulting in high energy consumption. Thus, a great change in the refining degree is achieved on average but the refining degree of the refined material may be non-uniform, comprising material refined to a great extent and material refined to a small extent.
Further, in all embodiments according to
As noted above, in the embodiments according to
Further, when the guide surface 21 of the third blade bar 14′″ is arranged, in the direction of travel of the first blade bar 14′ and the second blade bar 14″, between the first blade bar 14′ and an imaginary extension of the second blade bar 14″, as schematically shown in
Also when the guide surface 21 of the third blade bar 14′″ is arranged, in the direction of travel of the first blade bar 14′ and the second blade bar 14″, between an imaginary extension of the first blade bar 14′ and the second blade bar 14″, as schematically shown in
Further, when the guide surface 21 of the third blade bar 14′″ is arranged, in the direction of travel of the first blade bar 14′ and the second blade bar 14″, between imaginary extensions of the first blade bar 14′ and the second blade bar 14″, as schematically shown in
The side edges 23a, 23b of the third blade bar 14′″ being in contact with the side edges 24, 25 of the first blade bar 14′ and/or the second blade bar 14′ or with imaginary extensions thereof thus means herein that the third blade bar 14′″ is at least over some longitudinal portion thereof or over the whole longitudinal portion thereof as wide as that blade groove 15 or an imaginary extension of that blade groove 15 which is terminated by the third blade bar 14′″. The side edges 23a, 23b of the third blade bar 14′″ can be in contact with side edges 24, 25 of the first blade bar 14′ and/or the second blade bar 14′ or imaginary extensions thereof only by the lower part of the blade bars 14′, 14″, 14′″ or over the whole height thereof, depending on the desired proportion of control for the flow of the material to be refined and the steam generated during the refining, for example.
The larger the portion over which the side edges 23a, 23b of the third blade bar 14′″ are in contact with the side edges 24, 25 of the first blade bar 14′ and the second blade bar 14″ in the elevational direction, the higher proportion of the material travelling in the blade gap can be guided preferably into the blade gap. However, it is preferable for the solution that although in contact with the side edges 24, 25 of the first blade bar 14′ and the second blade bar 14″, the side edges 23a, 23b of the third blade bar 14′″ do not completely shut off the passage of steam, at least not into one of the adjacent grooves. This has been implemented in the solution in such a way that the side edges 23a, 23b of the third blade bar are in contact with the side edges of the first blade bar 14′ and the second blade bar 14″ only by the lower part, or in such a way that the guide surface 21 of the third blade bar 14′″ is not yet in its full height at the point of the second end 14b of the first blade bar 14′ and/or the second blade bar 14″, or in such a way that at least one of the side edges 23a, 23b of the third blade bar 14′″ is in contact with only the imaginary extension 24a, 25a of the side edge of the first blade bar 14′ or the second blade bar 14″.
Number | Date | Country | Kind |
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20095283 | Mar 2009 | FI | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FI2010/050194 | 3/12/2010 | WO | 00 | 9/15/2011 |
Publishing Document | Publishing Date | Country | Kind |
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WO2010/106225 | 9/23/2010 | WO | A |
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Entry |
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International Search Report for PCT/FI2010/050194. |
Written Opinion of the International Searching Authority for PCT/FI2010/050194. |
Number | Date | Country | |
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20120006924 A1 | Jan 2012 | US |