Solid material comminution or disintegration – Apparatus – Cooperating comminuting surfaces
Patent
1996-11-08
1997-12-09
Husar, John M.
Solid material comminution or disintegration
Apparatus
Cooperating comminuting surfaces
241296, 241297, B02C 712
Patent
active
056951361
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the disintegration and refining of lignocellulosic material in a disk refiner. More particularly, the present invention relates to a refining element for use in a refiner of that type.
BACKGROUND OF THE INVENTION
A disk refiner comprises two opposed refining discs, which are generally rotatable relative to each other, and where one or both of the disks are rotary. A plurality of refining elements arranged on the face of these refining disks form a pattern of bars and intermediate grooves. The refining disks are positioned so that the refining elements form a refining gap between the two refining disks, through which the fiber material is intended to pass outwardly from within. In this manner the disintegration of the lignocellulosic material is carried out by the bars of the refining elements.
The refining elements in the inner radial portion of the refining gap are generally formed with bars of a greater coarseness in order to carry out an initial disintegration, and to feed the material outwardly to the outer portion of the refining gap, where the disintegration and refining itself take place.
The refining of the material requires a large energy input, which is supplied by the rotation of the rotary refining disk or disks. The greatest portion of the energy is transformed to heat, as a result of which large amounts of steam are generated due to the water content in the material. The steam, substantially all of which is generated in the refining gap, has high pressure and flows both outwardly and inwardly in the refining gap.
To disintegrate and refine the fiber material by the bars of the refining elements, it is necessary in most cases to provide flow restrictions, or so-called dams, in the grooves between the bars. In this manner, the material is forced to move upwardly out of the grooves and to be worked between the bars in the refining gap. Unworked material is thus prevented from passing outwardly through the refining gap. These dams, however, obstruct the generated steam, which thereby disturbs the material flow, and has a negative effect on the capacity and operational stability of the refiner.
The aforesaid problems can be reduced by the present invention, which also offers additional advantages with regard to the quality of the refined material. According to the invention, co-operating refining elements on opposed refining disks are provided with radial zones, in which the bars are arranged in a denser or sparser relationship.
SUMMARY OF THE INVENTION
In accordance with the present invention, these and other objects have now been realized by the invention of apparatus for refining lignocellulose-containing material in a disk refiner comprising a pair of opposed relatively rotatable refining disks defining a refining gap for the lignocellulose-containing material therebetween. The apparatus includes a pair of refining disks including at least one refining disk comprising a refining disk surface including an inner refining zone section and an outer refining zone section disposed radially outwardly with respect to the inner refining zone section, the outer refining zone section including a first refining zone, a second refining zone disposed outwardly with respect to the first refining zone, and a third refining zone disposed outwardly with respect to the second refining zone, each of the first, second and third refining zones including a plurality of radially extending bars separated by a corresponding plurality of radially extending grooves, with the ratio of the bars to the grooves defining a bar density for each of the refining zones, the second refining zone having a first predetermined bar density and each of the first and third refining zones having a second predetermined bar density which is different from the first predetermined bar density. In a preferred embodiment, the second predetermined bar density is greater than the first predetermined bar density. In another embodiment, the second predetermined bar density is less than
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Obitz Lars
Rohden Lennart
Husar John M.
Sunds Defibrator Industries AB
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