Solid material comminution or disintegration – Apparatus – Cooperating comminuting surfaces
Patent
1998-06-17
2000-03-28
Fiorilla, Christopher A.
Solid material comminution or disintegration
Apparatus
Cooperating comminuting surfaces
241296, 162234, B02C 704, B02C 110
Patent
active
060420367
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to refining elements for use in refiners with flat or conical refining surfaces. More particularly, the present invention relates to the type of refiner used for working and refining lignocellulosic fiber material of both low and high material concentration.
BACKGROUND OF THE INVENTION
Refiners having flat refining surfaces generally comprise two refining discs, which rotate relative to each other and which have opposed refining surfaces. In this manner, one refining disc can be rotatable and the other stationary, or both refining discs can be rotatable in opposite directions. The refining surfaces generally consist of refining elements located on each refining disc. These refining elements are provided with a pattern of bars and intermediate grooves. Between the opposed refining elements a refiner gap is formed, through which the material is intended to pass outwardly while simultaneously being worked by the bars of the refining elements.
Refiners with conical refining surfaces comprise a rotor with a conical refining surface which is surrounded by a stator with an opposed conical refining surface. The angle of inclination to the rotor axis is generally less than 45.degree., preferably 10-30.degree.. The refining surfaces consist of refining elements located on the rotor and stator, respectively. These refining elements are provided with a pattern of bars and intermediate grooves. Between the opposed refining elements a refiner gap is formed, through which the material is intended to pass from the end with the smallest diameter to the end with the largest diameter, while simultaneously being worked by the bars of the refining elements.
The bars on the refining elements can be straight or angled, and the bar-groove ratio can be varied for achieving different refining results. The feed through the refiner gap is affected strongly by centrifugal forces. With increasing diameter in the direction of feed, the centrifugal force, and thus the feed force, also increases. The difference in diameter between the inlet and outlet of the refiner gap implies that the space for the material in the refiner gap can vary by up to 50% between the inlet and outlet portion of the refiner gap. These conditions limit the total capacity, and can cause problems with non-uniform quality of the refined material. Furthermore, there will also be a reduction in the total production due to wear of the bars on the refining elements.
One object of the present invention is to eliminate these problems by about a uniform feed through the entire refiner gap.
SUMMARY OF THE INVENTION
In accordance with the present invention, a more uniform material flow through the refiner gap can be obtained by forming the inlet portion of the refining elements more open and angular downstream of the direction of flow of the pulp therein. In this manner the refining result as well as the production therein can be improved. Indeed, an increase of capacity of from 20 to 25% can now be obtained.
In accordance with the present invention, these and other objects have now been accomplished by the discovery of a refining element for use in a refiner for lignocellulosic material comprising first and second relatively rotatable refining surfaces separated by a refining gap therebetween defining a refining path having an inlet having a first diameter and an outlet having a second diameter, the first diameter being less than the second diameter, a refining element comprising a refining surface including a plurality of raised bars alternating with a plurality of grooves, the plurality of raised bars at said inlet of said refining path having a first spacing and forming a first angle with respect to a radius or generatrix defining the refining path and a plurality of raised bars at the outlet of the refining path having a second spacing and forming a second angle with respect to the radius or generatrix, the first angle being between about 50.degree. and 85.degree. and the second angle being between about -25.de
REFERENCES:
patent: 100537 (1870-03-01), Loy
patent: 3974971 (1976-08-01), Reinhall
patent: 4023737 (1977-05-01), Leider et al.
patent: 5181664 (1993-01-01), Kohler
patent: 5362003 (1994-11-01), Virving
Bergquist Peter
Hawen Anders
Virving Nils
Fiorilla Christopher A.
Sunds Defibrator Industries AB
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