Solid material comminution or disintegration – Apparatus – Cooperating comminuting surfaces
Reexamination Certificate
1999-07-19
2001-05-08
Butler, Rodney A. (Department: 3725)
Solid material comminution or disintegration
Apparatus
Cooperating comminuting surfaces
Reexamination Certificate
active
06227471
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for working lignocellulosic fibrous material in a refiner with opposed refining means rotating relative to each other, one of which is stationary and one rotary, provided with refining elements, which between themselves form a refining gap with a refining zone for working the material. More particularly, the present invention relates to such a device in which the lignocellulosic material is supplied through a central opening in the stationary refining means to a feed zone located radially inside the refining zone, and most particularly, to a feeding element for the material, which is intended to be placed directly outside a central feeding device on the rotary refining means. The feeding element according to the present invention can be used in a refiner for the manufacture of various types of mechanical pulps, such as refiner mechanical pulp (RMP), thermomechanical pulp (TMP), chemimechanical pulp (CMP) and chemi-thermomechanical pulp (CTMP). The starting material can be wood chips or more or less worked pulp.
BACKGROUND OF THE INVENTION
In connection with the above-referenced type of refiners, in the inner portion of the feed zone the effect of centrifugal force on the supplied material is low. For this reason, the material supplied through the opening in the stationary refining means is generally not fed sufficiently rapidly through the feed zone to the refining zone, which is located radially outward from the feed zone. As a result, the material can clog in the feed zone, which results in friction losses and non-uniform feed, which in turn leads to a deterioration in the pulp quality. In order to overcome these problems, mechanical feeding devices can be arranged in the feed zone.
However, even if the material is transported out through the feed zone by means of central feeding devices, problems can still arise when it enters the refining zone in the refining gap. The material can thus be subjected to braking forces and to an ineffective mechanical action, which causes heat development and results in the material not being adequately worked. This results in unnecessarily high energy consumption.
SUMMARY OF THE INVENTION
In accordance with the present invention, this and other objects have now been realized by the invention of a feeding element for use in connection with a refiner for lignocellulosic fibrous material including a stationary refining member, a rotary refining member mounted for rotation in juxtaposition with the stationary refining member thereby forming a refining gap therebetween, a feeder for feeding the lignocellulosic fibrous material centrally to a feed zone within the refining gap and a refining zone extending radially outward from the feed zone, the feeding element comprising a feeding member having an upper surface for mounting on the rotary refining member at a location outwardly displaced from and directly adjacent to the central location of the feed zone, the feeding member including at least one radial feed bar projecting from the upper surface of the feeding member, the at least one radial feed bar including a body portion and a projecting portion extending laterally from the body portion at a location displaced from the upper surface of the feeding member. Preferably, the body portion includes a first side and a second side, and the projecting portion extends laterally from both the first and second sides of the body portion.
In accordance with one embodiment of the feeding element of present invention, the feeding element includes a plurality of the radial feed bars, and wherein the projecting portions extending laterally from each of the plurality of radial feed bars are spaced from adjacent ones of the projecting portions.
In accordance with another embodiment of the feeding element of the present invention, the feeding element includes a plurality of the radial feed bars, and wherein the projecting portions extending laterally from each of the plurality of radial feed bars are connected to adjacent ones of the projecting portions to form bridges between the plurality of radial feed bars, thereby creating closed channels beneath the bridges.
In accordance with another embodiment of the feeding element of the present invention, the feeding element includes a plurality of the radial feed bars extending substantially over the entire upper surface of the feeding member.
In accordance with another embodiment of the feeding element of the present invention, the outer portion of the feeding element extending radially from the feeding member includes a plurality of radially projecting bars for working the lignocellulosic fibrous material.
In accordance with another embodiment of the feeding element of the present invention, the feeding element comprises an annular feeding element extending entirely around the rotary refining member.
The feeding element according to the present invention thereby offers a solution to the aforesaid problems, in that it brings about a continued effective feed of the material and at the same time its acceleration from the feed zone, as well as some distance into the refining gap. Due to such effective feeding, the energy consumption in the refiner is thereby reduced.
The refining element according to the present invention comprises at least one feeding bar in which the upper edge of each feeding bar projects out at least on one side of the bar. The feeding element is intended to be placed on the rotary refining means in the refining gap directly outside the central feeding device, which can be attached to the rotary refining means or be a separate screw feeder extending into the refining gap between the refining means. The feeding bar or bars of the feeding element can be angular in relation to the radius in order to bring about optimum feeding. Alternatively, the feeding bar or bars can be radial in order to allow reversible motion while at the same time maintaining the feeding of the lignocellulosic material. In a preferred embodiment, the upper edge of the feeding bar projects out symmetrically from both sides of the bar.
REFERENCES:
patent: 3902673 (1975-09-01), Berggren
patent: 3957214 (1976-05-01), Berggren
patent: 4220290 (1980-09-01), Johansson
patent: 4355767 (1982-10-01), Johansson et al.
patent: 5040736 (1991-08-01), Obitz
Butler Rodney A.
Lerner David Littenberg Krumholz & Mentlik LLP
Valmet Fibertech Aktiebolag
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