Refining elements

Refining elements for use in a disk refiner for disintegrating and refining lignocellulose-containing material is disclosed including a pair of opposed refining elements on opposed refining disks which are relatively rotatable with respect to each other, the first and second refining elements including inner, intermediate and outer refining zones including pluralities of alternating bars and grooves extending substantially radially therealong, in which the bars on the inner refining zones on both refining elements extend outwardly at an angle with respect to the radius of the refining elements in different directions, the bars in the intermediate refining zones on both refining elements extend radially outward at an angle of less than about 15.degree. with respect to the radius of the refining elements, and the bars in the outer refining zones on both refining elements extend radially outward at an angle with respect to the radius of the refining element in the same direction with respect thereto.

FIELD OF THE INVENTION 
The present invention relates to the disintegration and refining of 
lignocellulosic material, such as mechanical pulp (TMP, CTMP), reject 
pulp, recycled fiber pulp and the like in a disk refiner. More precisely, 
the present invention relates to refining elements for use in a refiner of 
this type. 
BACKGROUND OF THE INVENTION 
Known disk refiners comprise two opposed refining disks which rotate 
relative to each other, one or both of which are thus rotary. A plurality 
of refining elements are arranged on the refining disks, and include a 
pattern of bars and intermediate grooves. The refining disks are 
positioned so that the refining elements form a refining gap therebetween, 
through which the fiber material is intended to pass outwardly from 
within, whereby disintegration is carried out by the bars of the refining 
elements. These bars can be of various designs and, thus, may be 
continuous or discontinuous, and of uniform of varying height. In certain 
cases serrated bars can be used. 
The fiber material is first defibered in the refining gap between the 
refining surface, i.e., the fibers are freed, which takes place in the 
interior portion of the refining gap where the distance between the 
refining surfaces is the greatest. The refining gap narrows thereafter 
outwardly so that the desired working of the fiber material is obtained. 
Large amounts of energy are thus required to bring about this working The 
material concentration can be between about 3% and 50%, which implies that 
simultaneously large amounts of steam are generated from the water 
associated therewith. 
The refining surfaces are formed in different ways, depending on the 
desired degree of working, and thus on the desired pulp quality. The pulp 
quality is also affected by other factors, for example the size of the 
refining gap, the liquid content in the fiber material, feed, temperature, 
etc. 
The appearance of the refining surfaces is of great importance, especially 
with regard to the fiber length of the material so worked. With a 
substantially radial orientation of the bars on the refining surfaces, a 
large proportion of long and well fibrillated fibers is obtained in the 
pulp. This can be explained by the fact that the fiber material orients 
itself in the refining gap with the fiber in a direction substantially 
parallel to the far edges. In this manner, defibering and working take 
place by virtue of the fact that the fiber material substantially rolls 
between the bars on opposed refining surfaces whereby the fibers are freed 
and fibrillated along their entire length. This type of pulp obtains high 
strength, and is therefore particularly valuable for many applications 
such as for newsprint. The energy consumption during the manufacture of 
this type of pulp is relatively high. 
At an oblique orientation of the bars in relation to the radius, the 
proportion of long fibers in the pulp decreases, because in this case the 
bar edges exert a cutting effect on the fiber material. At the same time 
that the cutting effect increases, the fibrillation effect decreases. The 
strength properties of this pulp type are certainly lower, but the pulp is 
particularly suitable for use in the manufacture of fine paper qualities 
where forming, printability and opacity are appreciated. 
The bar angle is also of importance for feeding the material through the 
refining gap. When the bars are angled obliquely outward rearward with 
respect to the direction of rotation, an outward pumping action is 
obtained, while angling in the opposite direction yields a braking effect. 
The stay time of the material in the refining gap is thus affected by the 
angle of the bars. 
Known refining elements are specifically designed so as to produce desired 
properties in the pulp. This implies in many cases that compromises must 
be made with regard to the design of the refining surfaces in order to 
bring about a suitable balance between fibrillation and cutting of the 
fibers and, on the other hand, between feeding and braking. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, these and other objects have now 
been accomplished by 10 the provision of apparatus for use in a disk 
refiner for the disintegration and refining of lignocellulose-containing 
material which comprises a pair of refining disks rotatable relative to 
each other thereby providing a refining gap for the 
lignocellulose-containing material therebetween, the apparatus comprising 
a first refining element disposed on one of the pair of refining disks, 
and a second refining element disposed on the other of the pair of 
refining disks facing the first refining element, the first and second 
refining elements thereby defining corresponding radii, the first refining 
element including a plurality of refining zones disposed radially 
outwardly thereon, including an inner refining zone, and intermediate 
refining zone, and an outer refining zone, the second refining element 
including a plurality of refining zones disposed radially outwardly 
thereon and including an inner refining zone at a location corresponding 
to the inner refining zone on the first refining element, an intermediate 
refining zone at a location corresponding to the intermediate refining 
zone on the first refining element, and an outer refining zone at a 
location corresponding to the outer refining zone of the first refining 
element, each of the refining zones comprising a plurality of alternating 
bars and grooves extending substantially radially therealong, the bars on 
the inner refining zones on the first and second refining elements 
extending radially outward at an angle with respect to the radius of the 
refining elements in different directions with respect thereto whereby the 
bars lie in intersecting planes, the bars in the intermediate refining 
zones on the first and second refining elements extending radially outward 
at an angle of less than about 15.degree. with respect to the radius of 
the refining elements, and the bars on the outer refining zones on the 
first and second refining elements extending radially outward at an angle 
with respect to the radius of the refining elements in the same direction 
with respect thereto. 
In accordance with a preferred embodiment of the apparatus of the present 
invention, the bars on the inner refining zones on the first and second 
refining elements extend radially outward at an angle of between about 
10.degree. and 30.degree. with respect to the radius of the refining 
element. 
In accordance with another embodiment of the apparatus of the present 
invention, the bars on the outer refining zones on the first and second 
refining elements extend radially outward at an angle of between about 
10.degree. and 30.degree. with respect to the radius of the refining 
elements. 
In accordance with another embodiment of the apparatus of the present 
invention, the bars on the outer refining zones on the first and second 
refining elements are substantially parallel to each other. 
In accordance with another embodiment of the apparatus of the present 
invention, the plurality of alternating bars and grooves extending 
substantially radially along the first and second refining elements in 
each of the inner, intermediate and outer refining zones include a 
plurality of substantially parallel extending bars and grooves. In a 
preferred embodiment, each of the plurality of alternating bars and 
grooves in each of the inner, intermediate and outer refining zones 
includes a plurality of groups of the alternating bars and grooves. 
In accordance with another embodiment of the apparatus of the present 
invention, the plurality of bars in at least one of the inner, 
intermediate and outer refining zones on the first and second refining 
elements extends radially outward at an angle substantially corresponding 
to the radius of the refining elements. 
In accordance with the present invention, the refining elements can be 
formed so that they yield an optimum pulp and at the same time minimize 
the energy consumption. To this end, cooperating reining elements are 
formed with bars and grooves in a number of restricted zones located 
radially outside each other where each refining element comprises at least 
three such zones. According to the invention, the bars in an opposed inner 
zone on both refining elements are oblique in different directions in 
relation to the radius of the refining elements (preferably at an angle of 
between about 10.degree. and 30.degree.), so that the bars on opposed 
refining elements cross each other. The bars in an intermediate zone are 
substantially radial (preferably at an angle of &lt;15.degree., and most 
preferably of, &lt;10.degree.), and in an outer zone the bars form an angle 
with the radius in the range of between about 10.degree. and 30.degree. in 
the same direction. The bars on opposed refining elements can thus be 
substantially parallel to each other. 
The bars can be divided into several radial zones, each comprising one or 
more groups of bars, where the bars in each such group are substantially 
parallel to each other. Alternatively, the bars within one zone can form 
substantially the same angle with the radius. It is also possible to 
arrange the bars so that their angle with respect to the radius changes 
successively across the refining surface.

DETAILED DESCRIPTION 
The refining surfaces of the cooperating refining elements shown in the 
Figures, are divided into three zones, where each zone comprises a portion 
of the radial extension of the refining surface. These include an inner 
zone A, an intermediate zone B, and an outer zone C. Each zone is provided 
with bars forming an angle with the radius of the refining element. The 
bars are arranged in a pattern which tightens (with the spacing between 
the bars decreasing) radially outward from one zone to another. 
The angle in the inner zone A is between about 10.degree. and 30.degree. 
with respect to the radius. When the refining elements are used in a 
refiner, the bars are angled for outward feed. In zone A it is desired 
that feeding take place at the same time as an initial defibering of the 
material is desired. The refining elements are formed so that the distance 
between opposed refining elements in the refiner in inner zone A is of 
such a size that neither cutting nor fibrillation takes place to a 
significant degree. 
The angle in the intermediate zone B is less than about 15.degree., and 
preferably less than about 10.degree. C., in relation to the radius. The 
bars, thus, shall be substantially radial. The distance between opposed 
refining elements in this zone is sorter, and a certain working of the 
fibers thus takes place therein. The angle of the bars in this case 
implies a balancing between feeding and working. 
In the outer zone C the final working of the fibers takes place. The angle 
of the bars in relation to the radius can in this case vary between about 
10.degree. and 30.degree., and the bars on opposed refining elements are 
directed in the same direction in relation to the radius. The bars in this 
case can be substantially parallel. In view thereof, the fibrillation 
effectively increases and the cutting effectively decreases, while at the 
same time the stay or residence time is extended due to the fact that the 
bars on one refining element counteract the feed. 
All of the above, taken together, results in effective working, such that a 
desired pulp quality can be obtained at a lower energy input. Full size 
tests, for example, have shown that the engine load could be lowered from 
10.5 MW to 9 MW, while maintaining pulp quality. 
The bars in each zone A, B and, C can form one or more groups in which the 
bars within each group are mutually parallel to each other. 
Instead of dividing the refining surface into three radial zones, more 
zones can be arranged. It is also possible to change the bar angle 
successively along the refining surface. The bars can thus be either 
straight or arched. 
Although the invention herein has been described with reference to 
particular embodiments, it is to be understood that these embodiments are 
merely illustrative of the principles and applications of the present 
invention. It is therefore to be understood that numerous modifications 
may be made to the illustrative embodiments and that other arrangements 
may be devised without departing from the spirit and scope of the present 
invention as defined by the appended claims.