Abstract:
A refiner plate for refining lignocellulosic materials has an injector inlet having a substantially triangular protrusion. The substantially triangular protrusion may feed the incoming lignocellulosic material into the refining zone and may distribute the material around the refining zone.

Description:
CROSS RELATED PATENT APPLICATION 
       [0001]    This application claims the benefit of application Ser. No. 60/837,619, filed Aug. 15, 2006, which is incorporated in its entirety by reference. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    This disclosure generally relates to refiners and refiner plates for refining lignocellulosic materials, such as fibers and other substances containing cellulose and lignin. This disclosure generally relates to the inlet of a refiner plate, including refiner plates designed for use in disc refiners, conical refiners, and conical-disk refiners. 
         [0003]    In high consistency mechanical pulp refiners, lignocellulosic materials—such as wood fibers—are worked between two relatively rotating surfaces on which refiner plates are mounted. The plates typically have radial bars and grooves. The bars provide impacts or pressure pulses which separate and fibrillate the fibers, and the grooves enable feeding of the fibers between the refiner discs. Typically, each refiner plate has a radially inner inlet zone which is adapted for receiving wood chips, previously refined fiber, and/or other lignocellulosic material and at least one radially outer refining zone. 
         [0004]    The inlet zone generally feeds the incoming lignocellulosic material into the refining zone and distributes the material around the refining zone. In many conventional refiners, the inlet zone of the refiner plates generally either feeds well or distributes well. In feeding and distributing the lignocellulosic material, the refiner plate&#39;s inlet zone may perform an initial refining operation on the cellulosic material to reduce the size of the material. 
         [0005]    A conical-disk refiner, for example, may have good feeding ability in the first zone, occasionally referred to as the “flat zone,” as the centrifugal forces force the feed material along the gap created between two opposing refining plates. A second zone in a conical-disk refiner is the conical zone. In general, centrifugal forces normally project the feed material from the conical zone from the rotating element (which may be a smaller convex cone or plug) into the stationary element (which may be the larger concave element or shell). The feeding ability of the conical zone may not be as good as that of the flat zone. Accordingly, the conical zone may rely primarily on a forward flow of steam to promote forward movement of the pulp towards the refiner discharge which is typically located at the end of the conical zone or its larger diameter end. 
         [0006]    A conical-disk refiner may generally lack significant mechanical centrifugal forces forcing the feed material from the discharge of the flat zone into the conical zone. Due to the absence of sufficient motive forces, the feed material may stall at the junction of the first and second zones. Stalling may potentially cause feed instabilities and other difficulties in operating the refiner, especially at higher production rates. In general, features on some conventional refiner plate designs may throw the fiber against the stator conical zone but may apply insufficient mechanical forces to feed forward the fiber along the gap between the conical zone rotor and stator. 
         [0007]    An improved inlet section has been developed for refiners—such as conical, disk, and conical-disk refiners—and refiner plates for refining lignocellulosic material. In particular, an improved rotating element of a conical zone in a conical-disk refiner has been developed. The rotating element may improve feeding the lignocellulosic material forward from the junction of the flat and conical zones and may allow for a good distribution of the feed material around the rotating and stationary elements. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0008]    In one embodiment, the invention may be used in a conical-disk refiner for refining lignocellulosic material. In other embodiments, the invention may be used in a conical refiner or a disk refiner. 
         [0009]    In a conical-disk refiner, feeding the material from the junction of the flat and conical zones and into the conical zone may have certain design-related goals, one or more of which may be achieved in accordance with the present invention: 
         [0010]    (1) In general, the inlet to the rotor conical zone preferably should be relatively open to ease the feed into the conical zone. It is preferable that approximately two-thirds of the chord length of the inlet of the conical zone be open so that feed may easily enter the conical zone. 
         [0011]    (2) In general, the features at the inlet of the rotor conical zone preferably should impart a forward feeding mechanical force as the inlet contacts the feed material. 
         [0012]    (3) In general, the rotor inlet features preferably should promote distribution of the feed material around substantially the entire surface of the rotor conical zone. Concentrating the feed in small concentrated areas of the inlet preferably avoided. This preference for a conical rotor may be less important than in a flat zone refiner, because the conical rotor typically expels the pulp into the stationary element, thus generally forcing a distribution of the feed. 
         [0013]    (4) In general, the rotor inlet feature preferably should be designed to operate equally in both directions of rotation. Many users of this type of refiner may regularly change the operating direction of rotation. Changing the operating direction of rotation may extend the life of the refiner plates. 
         [0014]    An inlet of the rotor conical zone preferably should operate against any standard inlet of a stator conical zone plate. The inlet should preferably have one or more substantially triangular protrusions at the inlet section. The protrusions may extend over the base level of the plate (which is defined by the bottom of the grooves in the outer section) and may reach a level substantially similar to the height of the bars from the refining section. 
         [0015]    The substantially triangular shape of the protrusion is defined from an elevation view, where the base of the triangle is formed at the inlet of the rotor conical zone segment. The substantially triangular shape may also protrude a small amount beyond the inner portion of the base plate, preferably as much as the refiner geometry can allow without touching other surfaces is desired. The protrusion may reach into the gap separating the flat zone from the conical zone. The apex of the triangle may generally point radially outwards towards the outer periphery of the rotor conical zone segment. The sides of the triangles may create “forward feeding” surfaces that may generally impart a force vector on the feed material, helping propel the feed material forward towards the outer part of the conical zone. 
         [0016]    The base of the triangular section of the feeding protrusion preferably covers approximately one-third of the arc length of the segment (or approximately one-sixth when 2 protrusions are used). For example, the range for the protrusions may cover 20% to 45% of the arc length of the segment inlet, and all sub-ranges therebetween. The slope of the sides of the triangles relative to a centerline passing through the middle of the triangle and aligned from the inlet of the segment to the periphery of the segment may preferably be in the range of 20° to 75°, and more preferably between 30° and 60°, and all sub-ranges therebetween. The lower corners of the segment may be sharp or, alternatively, may be slightly rounded off in order to minimize the likelihood of being easily chipped off or damaged by contraries that can be found in the feed material. Preferably, there is a positively feeding vector in the part of the triangle that extends beyond the limit of the refiner segment itself to help propel the feed material from the junction of the flat and conical gaps and into the conical gap. The apex of the triangle is preferably rounded for preventing chipping off the sharp edge, but also because a rounded off tip may promote the distribution of the feed around the rotor surface. 
         [0017]    The substantially triangular protrusion may have a radius that may be substantially parallel with the base of the plate. Alternatively, the radius may not be substantially parallel with the base of the plate. The limit on the size of the radius is generally dictated only by practical constraints and considerations. 
         [0018]    For example, it is preferable to maintain the feed angle at the inlet of the triangle within the range of 15-75°, and it is preferable to maintain a strong enough construction to avoid a feeding element that is structurally weak and may break in the refiner. In addition, the draft angle, or the side angle on the triangles relative to the axis running from the center of the refiner disk and across the base plate, should preferably—though not necessarily—be as close to 0° as possible, subject to limitations inherent in the manufacturing process. If a negative draft angle can be achieved cost-efficiently in the manufacturing process (the casting process typically demands a positive draft angle, so additional machining or the use of mold cores may be necessary), the negative draft angle would be preferable because it would increase the positive feeding effect by reducing the tendency to throw material into the stator side. 
         [0019]    The substantially triangular protrusion may be approximately an equilateral triangle, an isosceles triangle, or a scalene triangle. The substantially triangular protrusion may have all acute angles, two acute angles and an obtuse angle, or two acute angles and a right angle. A substantially isosceles triangular protrusion is preferable due to its symmetry, which thus may permit reversal of the direction of rotation without substantially altering the refiner plate&#39;s performance. 
         [0020]    In other embodiments, the substantially triangular protrusion located in a refiner plate&#39;s inlet may be used in a conical refiner or a disk refiner. 
         [0021]    A refiner plate has been developed for refining lignocellulosic material. The refiner plate comprises a refining zone and an inlet zone. The inlet zone comprises at least one substantially triangular protrusion having three angles. Preferably, each of the angles at the base of the triangle is between 15° and 75°. The refiner plate may be a rotor or stator plate in any refiner for refining lignocellulosic material, including, for example, a conical-disk refiner, a disk refiner, or a conical refiner. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is an illustration of a conical-disk refiner showing the refiner plates for the flat section and the conical section. 
           [0023]      FIGS. 2A-C  are illustrations of a prior art refiner plate for the conical section of a conical-disk refiner. 
           [0024]      FIGS. 3A-C  are illustrations of an embodiment of a refiner plate having a triangular injector inlet in a conical-disk refiner. 
           [0025]      FIG. 4  is an illustration of another embodiment of a refiner plate having a triangular injector inlet. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]      FIG. 1  illustrates a partial cross-sectional view of the configuration of refiner plates in a conical-disk refiner. There are two refining sections: conical section  102  and flat section  104 . There is a gap  106  between conical section  102  and flat section  104  where the feed transitions from one refining zone to the next. Conical section  102  contains a rotor plate  108  and a stator plate  110 . Flat section  104  similarly has a rotor plate  112  and a stator plate  114 . 
         [0027]    In general terms, lignocellulosic material enters the flat section at entrance  116 . From there, the lignocellulosic material enters refining zone  118 . Refining zone  118  contains a pattern of bars and grooves, which provide impacts or pressure pulses to facilitate separation and fibrillation of the fibers. As the lignocellulosic material is worked between the plates, steam may be generated. 
         [0028]    From refining zone  118 , the lignocellulosic material flows through the gap  106  to the injector inlet  120  of rotor plate  108  in conical section  102 . The feed zone forces the lignocellulosic material forward and distributes the material amongst the refining section  122 , which contains a pattern of bars and grooves to provide impacts or pressure pulses to facilitate separation and fibrillation of the fibers. After being worked between the rotor  108  and stator  110  in refining zone  122 , the refined lignocellulosic material exits at exit  124 . 
         [0029]      FIGS. 2A ,  2 B, and  2 C show a prior art configuration of an inlet in a rotor plate in a conical section of a conical-disk refiner.  FIG. 2A  shows a cross-sectional view of A-A of  FIG. 2B .  FIG. 2C  shows a cross-sectional view of C-C of  FIG. 2B . In these figures, the same items share the same numbers. 
         [0030]    In  FIG. 2A , the lignocellulosic material flows from the gap  206  to the injector inlet  220  of rotor plate  208 . The feed zone forces the lignocellulosic material forward and distributes the material amongst the refining section  222 , which contains a pattern of bars and grooves to provide impacts or pressure pulses to facilitate separation and fibrillation of the fibers. After being worked between the rotor  208  and stator  210  in refining zone  222 , the refined lignocellulosic material exits at exit  224 . 
         [0031]      FIG. 2B  shows an overview of a prior art configuration of an inlet in a rotor plate in a conical section of a conical-disk refiner. The inlet protrusions  220  have an approximately square base with a triangular portion pointed toward refining section  222 . The inlet protrusions  220  cause frictional forces  230 .  FIG. 2C  shows inlet protrusions  220  and frictional forces  230  and centrifugal forces  232 . Although it is believed that the frictional and centrifugal forces, as shown in  FIGS. 2B and 2C , are more or less accurate, they are shown for illustrative purposes only. 
         [0032]      FIGS. 3A ,  3 B, and  3 C show an embodiment of an inlet having a substantially triangular protrusion in a rotor plate in a conical section of a conical-disk refiner. Although shown in an embodiment related to the conical section of a conical-disk refiner, an inlet having a substantially triangular protrusion may be employed in a flat section of a conical-disk refiner, in a disk refiner, or in a conical refiner. Similarly, an inlet having a substantially triangular protrusion may be employed in either a rotor plate or a stator plate, even though depicted with respect to a rotor plate in the conical section of a conical-disk refiner. 
         [0033]      FIG. 3A  shows a cross-sectional view of A-A of  FIG. 3B .  FIG. 3C  shows a cross-sectional view of C-C of  FIG. 3B . In these figures, the same items share the same numbers. 
         [0034]    In  FIG. 3A , the lignocellulosic material flows from the gap  306  to the injector inlet  320  of rotor plate  308 . The feed zone forces the lignocellulosic material forward and distributes the material amongst the refining section  322 , which contains a pattern of bars and grooves to provide impacts or pressure pulses to facilitate separation and fibrillation of the fibers. The precise pattern of bars and grooves is unimportant to the present invention, and any conventional or nonconventional pattern is sufficient, so long as commercially practical and/or technically feasible. After being worked between the rotor  308  and stator  310  in refining zone  322 , the refined lignocellulosic material exits at exit  324 . 
         [0035]      FIG. 3B  shows an overview of an embodiment configuration of an inlet having a substantially triangular protrusion in a rotor plate in a conical section of a conical-disk refiner. As shown, there are a refining zone  322  and an inlet zone containing the substantially triangular inlet protrusion  320 . The substantially triangular inlet protrusion  320  has a base  360 , side  362 , and side  364 . In alternative embodiments, there are two or more substantially triangular inlet protrusions on the refiner plate. 
         [0036]    Preferably, the base  360  and the sides  362  and  364  are substantially straight as depicted in the embodiment shown in  FIG. 3B , although greater amounts of deviation from substantially straight are permitted in other embodiments. For example, they may be individually or collectively arcuate, jagged, or some other curvilinear form. As shown, the base  360  preferably extends beyond plate&#39;s base  370 , although the base  360  may terminate in the same plane of the termination of base  370 . Alternatively in a separate embodiment, base  370  may extend beyond base  360  of the substantially triangular protrusion. In  FIG. 3B , the base  360  is substantially parallel to the base  370 . In other embodiments, the base  360  is not substantially parallel to the base  370 . 
         [0037]    In an embodiment, the base of the triangular section of the feeding protrusion may preferably cover approximately one-third of the arc length of the segment (or approximately one-sixth when two protrusions are present). For example, the range for the total length of bases for all protrusions may cover 20 to 45%, preferably 25 to 40%, and more preferably 30-35% of the arc length of the segment inlet, and all sub-ranges therebetween. 
         [0038]    As shown in  FIG. 3B , the substantially triangular shape has three angles: angle  350 , angle  352 , and angle  354 . These angles correspond to the three corners of the substantially triangular shape. As shown in  FIG. 3B , angles  350  and  352  are approximately equivalent, forming an approximately isosceles triangular protrusion. In other embodiments, the substantially triangular protrusion  320  may be a substantially equilateral triangular protrusion or a substantially scalene triangular protrusion. One of angles  350 ,  352 , and  354  may approximately be a right angle. 
         [0039]    Preferably, angles  352  and  350  are between 15° and 75°, more preferably between 30° and 60°, and even more preferably between 40° and 50°, and all sub-ranges therebetween. As shown in  FIG. 3B , the corners corresponding to each of angles  350 ,  352 , and  354  are preferably substantially rounded. It is believed that rounding the corners minimizes the likelihood of being chipped or damaged by contraries in the feed material. In other embodiments, the angles are not substantially rounded. 
         [0040]    Preferably, the feed angle at the inlet of the triangle is within the range of 15-75°, and it is preferable to maintain a strong enough construction to avoid a feeding element that is structurally weak and may break in the refiner. In addition, the draft angle, or the side angle on the triangles relative to the axis running from the center of the refiner disk and across the base plate should preferably—though not necessarily—be as close to 0° as possible, subject to limitations inherent in the manufacturing process. In fact, a negative draft angle is preferable because it would increase the positive feeding effect by reducing the tendency to throw material into the stator side. 
         [0041]    In  FIG. 3B , angle  354  corresponds to the apex of the substantially triangular shape  320 . In some embodiments, the apex may protrude, either substantially or not, into the refining zone. As shown in  FIG. 3B , the apex does not protrude into refining zone  322 . 
         [0042]    As shown in  FIG. 3B , the substantially triangular inlet protrusion  320  causes frictional forces  330 .  FIG. 3C  shows the substantially triangular inlet protrusion  320  and frictional forces  330  and centrifugal forces  332 . Although it is believed that the frictional and centrifugal forces, as shown in  FIGS. 3B and 3C , are more or less accurate, they are shown for illustrative purposes only. However, it should be noted that the present invention is not limited to the direction or magnitude of any particular frictional or centrifugal force. 
         [0043]      FIG. 3C  depicts a pattern of bars  380  and grooves  382 . The top  366  of the substantially triangular protrusion is depicted as taller than the grooves. In other embodiments, the top  366  may be substantially the same height as bars  380  (or some subset of bars  380 ). In yet further embodiments, the top  366  may be shorter than bars  380  (or some subset of bars  380 ). 
         [0044]    As shown in  FIG. 3C , the substantially triangular protrusion  320  has a substantially rectangular cross-section formed by top  366  and sides  368  with rounded corners. In other embodiments, the substantially triangular protrusion  320  has a substantially trapezoidal—either isosceles or not—cross-section. In yet further embodiments, the substantially triangular protrusion does not have rounded corners. 
         [0045]      FIG. 4  shows another embodiment of an inlet of a refiner plate having a substantially triangular protrusion. The refiner plate&#39;s feed zone forces the lignocellulosic material forward and distributes the material amongst the refining section  422 , which contains a pattern of bars and grooves to provide impacts or pressure pulses to facilitate separation and fibrillation of the fibers. Some of the refining bars are labeled as  480 . The precise pattern of bars and grooves is unimportant to the present invention, and any conventional or nonconventional pattern is sufficient, so long as commercially practical and/or technically feasible. In the embodiment shown in  FIG. 4 , the bars  480  are substantially parallel, and the inlets of the bars are arcuate from the centerline of the plate to the left and right edges of the plate. Whether the inlets of the bars  480  form an arc or some other configuration is generally a design choice based on operational considerations, such as composition of the lignocellulosic material, refiner capacity, refiner type, etc. 
         [0046]    As shown in the embodiment of  FIG. 4 , the substantially triangular protrusion  420  has three sides: base  460 , side  462 , and side  464 . Base  460 , which is substantially straight, protrudes beyond the plate&#39;s base  470 . In other embodiments, base  460  is not substantially straight. For example, the base of the substantially triangular protrusion may be arcuate, jagged, or some other curvilinear form. Sides  462  and  464  are generally arcuate, though they also may be substantially straight, jagged or some other curvilinear form. Furthermore, sides  462  and  464  may form an arc that bows outwardly from the center of the substantially triangular protrusion, rather than inwardly as depicted. 
         [0047]    Side  462  and base  460  meet at corner  490 . As shown, corner  490  is slightly rounded, although it may be more or less rounded in other embodiments. As depicted in this embodiment, the substantially triangular protrusion has an apex  494  that protrudes into refining zone  422 . Furthermore, apex  494  does not form a corner; rather, apex  494  transitions into multiple refining bars: refining bar  496  and refining bar  498 . In other embodiments, apex  494  transitions into a single refining bar or into more than two refining bars. 
         [0048]    The transition, if any, from the substantially triangular protrusion into a refining bar may be relatively smooth or disjointed. That is, the surface of the refining bars  496  and  498  may not be in substantially the same plane as the surface of the substantially triangular protrusion  420 . And if they are not in the same plane, the transition between the refining bars and the substantially triangular protrusion may be gradual or sudden. 
         [0049]    Although  FIG. 4  depicts a single substantially triangular protrusion  420 , a single refiner plate may contain multiple substantially triangular protrusions in accordance with other embodiments 
         [0050]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.