REFINER PLATE TO PREVENT GROOVES PLUGGING
A refiner plate includes at least one refining zone including a first plurality of refining bars and a plurality of grooves. At least one groove of the plurality of grooves has a first width between adjacent refining bars of the first plurality of refining bars at an inlet of the at least one refining zone narrower than a second width along a remaining portion of the at least one groove. At least one of the adjacent refining bars of the first plurality of refining bars has a widened portion in a circumferential direction of the refiner plate at an inlet portion of the at least one refining zone.
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This application claims the benefit of U.S. Provisional Application No. 63/449,735, filed Mar. 3, 2023, the content of which is hereby incorporated herein by reference in its entirety.
BACKGROUNDUnless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to being prior art by inclusion in this section.
In the refining of lignocellulosic materials, there is often a need to apply low intensity refining energy to furnishes (e.g., stock). Refining is generally achieved by using refiner plate designs featuring arrays of substantially parallel bars and grooves, and the intensity of the refining energy is defined by the inverse of the number of bars. Low intensity refining is achieved with a large number of bars on the refiner plates. In all applications, and especially in low consistency refining where usually 3.0-5.5% of the stock is fiber, and the rest is water, there is a point at which the probability of plugging the grooves with unseparated particles such as wood chips, wood particles, paper flakes, etc., fiber bundles or contaminants such as pieces of plastic, metal, stones, etc. (especially in recycled grades) becomes substantial.
The plugging point is primarily related to the groove width in comparison to the size of larger particles. Generally, if the particles are similar sized or slightly wider than the grooves, there is a probability that they will be forced into the inlets of the grooves via centrifugal forces and/or flow pattern of the incoming stock through the plates. If the size differential and compressibility of the particles is a match, those particles will stop in the grooves, wedge themselves solidly, and plug the grooves. This will gradually restrict the flow capacity of the refiner as more grooves become plugged over time. The plugging effect causes a significant loss of lifetime for the refiner plates, and often forces a mill to make unplanned maintenance stops to replace the refiner plates.
Refiner plate designs typically use bars of constant width, or sometimes bars having a tapered width-either with bars narrower at the inlet of a zone, or alternatively wider at the inlet of a zone. Some designs feature bars that change width between zones, for example, getting wider in zones with a lower bar density, but the bar widths are substantially constant, such as shown in
One way to prevent plugging is to use refiner plate having wider grooves, but this causes the refining intensity to increase and results in poor fiber development. Flaring groove widths (width narrowest at inlet of bar refining section and gradually increasing towards the periphery) offer some improvement in plugging reduction since particles that can squeeze through the inlet should be able to move forward in a groove that gets wider along its length. Unfortunately, this benefit is limited by two aspects: first, the rate of groove width increase is generally very slow which does not provide the required plugging prevention—those grooves are often observed to be plugged; and second, flaring grooves generally result in a loss of number of bar crossings for the stock compared to parallel bar designs—this goes against the desired target of increasing bar crossings.
There is a need for a refiner plate design that provides grooves that are narrower than a size normally allowed by the raw material without increased plugging tendencies, thereby reliably maintaining the flow capacity of a refiner throughout the lifetime of the refiner plates and permitting application of low intensity refining to the furnish in order to maximize the development of its properties.
Aspects and features of the various embodiments will be more apparent by describing examples with reference to the accompanying drawings, in which:
While certain embodiments are described, these embodiments are presented by way of example only, and are not intended to limit the scope of protection. The apparatuses, methods, and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the example methods and systems described herein may be made without departing from the scope of protection.
Aspects of the present disclosure can provide particle size filtering at the inlets of refiner plate grooves. Providing filtering at the groove inlets may prevent particles likely to plug from entering the grooves. Any particles that pass the groove inlet are unlikely to get stuck in the groove past the entry point. The particle size filtering inlet may be applied at the inlet of any zone that may have a tendency to plug based on the groove width and the incoming stock conditions. For example, the particle size filtering can be applied at the inlet (e.g., the inner end) of all the refining zones of a refiner plate, at the inlet of less than all the refining zones of a refiner plate, or at the inlet of only one zone of the refiner plate.
According to aspects of the present disclosure, inlet filtering may be accomplished by forming narrowed grooves using refining bars that are wider at the inlet of a refining zone than along the remaining length of the groove. The widened refining bars may be formed by widening the bar as a step, a chamfer, a curved profile, or a combination of those configurations. Widened portions of a bar may be formed on one side of the bar only or may be distributed evenly or unevenly between the two sides of the bar. The widened portion may be short, thereby preventing the widened portion from becoming the location where particles can be trapped. If a particle can squeeze through the narrowed groove inlet created by the widened bars, then the particle should be free to continue flowing along the remainder of the groove.
The widened portions 110a, 110b may narrow the groove 140 between the widened portions 110a, 110b of the refining bars 100a, 100b at the inlet of a refining zone thereby restricting the size of a particle entering the groove 140. Since the groove 140 becomes wider between the narrow portions 120a, 120b of the widened refining bars 100a, 100b, any particle having a size that can pass between the widened portions 110a, 110b of the refining bars 100a, 100b at the inlet of a refining zone is unlikely to become trapped as it moves along the groove 140. The widened portions 110a, 110b of the refining bars 100a, 100b may include ramps 150a, 150b or other structures configured to deflect larger particles unable to pass through the inlet towards and into the refining gap between the refiner plates.
The wide portions 260a, 260b of the refining bars 250a, 250b may have an increased width of approximately 0.2-1.5 mm over the width of the narrow portions 255a, 255b of the refiner bars 250a, 250b. The wide portions 260a, 260b of the refining bars 250a, 250b may narrow the groove 270 at the inlet 210 of the refining zone 220 by 5-30% of the groove width between the narrow portions 255a, 255b of the refining bars 250a, 250b.
The refining bar configuration of the present disclosure can result in a narrow groove 270 between wide portions 260 of adjacent refining bars 250 at the inlet 210 of the refining zone 220 and a wide groove 275 that is wider than the narrow groove 270 extending from the transition portions 265 substantially the remaining length of the adjacent refining bars 250. In some implementations, all the refining bars may have wide portions that narrow the grooves between the wide portions of adjacent refining bars at the inlet of a refining zone. In some implementations, less than all the refining bars may have wide portions that narrow the grooves between the wide portions and adjacent refiner bars without widened portions at the inlet of a refining zone. In some implementations, all the refining zones may include refining bars having wide portions at the inlet. In some implementations, less than all the refining zones may include refining bar having wide portions at the inlet.
Particles larger than the narrow groove 270 between the wide portion 260 of the refining bar 250 may be deflected by ramps 280 or chamfers on the wide portions 260 towards and into the refining gap between opposing refiner plates where they will be separated into smaller particles.
The transition portion of the refining bar may be formed in a variety of different shapes.
The refining bar 330 illustrated in
The refining bar 350 illustrated in
In some implementations, the transition portion of the refining bars may be provided on a chamfer or ramp that faces the inlet of the refiner plate.
In
In some implementations, the refining bars that face the inlet of the refiner plate may have a chamfer or ramp. The chamfer or ramp may deflect any material that is fed towards the restrictive inlet of the refining zone towards the refining gap in between the opposing refining discs.
The chamfers or ramps can reduce the potential to trap particles at the inlet of the given refining zone that may cause restriction of flow into the grooves between the refining bars and through the refiner. Other configurations of chamfers or ramps may be provided without departing from the scope of the present disclosure.
Widening the refining bars at a fixed radial position can cause a flow restriction due to a drop in available volume at a given radial location. According to aspects of the present disclosure, the radial location of the refining zone inlet may be distributed relative to the center of the refining disk and arranged at an angle relative to a radial arc running across the refiner plate segment. The refining zone inlet may be arranged in a sawtooth pattern, a chevron pattern, a scattered transition, etc. The positioning of the refining bar ends may follow a curved line, a straight line, or a combination.
Alternatively, the length of individual refining bars at the refining zone inlet may be alternated to prevent radial flow restriction.
As illustrated in
Widening of the refining bars in a circumferential direction of a refiner plate or refiner plate segment at the inlet of a refining zone can apply where the start of one refining zone is not connected to a previous refining zone, but it can also apply where two or more refining zones are connected via a number of bars, dams, links, or any other means.
Referring to
It should be appreciated that the examples of
In some implementations, a restrictive refining zone inlet may be provided by alternating a standard refining bar and a widened refining bar.
The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the protection. For example, the example apparatuses, methods, and systems disclosed herein can be applied to single disc, double disc, counter-rotating, flat, conical, cylindrical or any other type of refining equipment, running at low, medium, or high consistency. Also, the features and attributes of the specific example implementations disclosed above may be combined in different ways to form additional implementations, all of which fall within the scope of the present disclosure.
Although the present disclosure provides certain example embodiments and applications, other embodiments that are apparent to those of ordinary skill in the art, including embodiments which do not provide all of the features and advantages set forth herein, are also within the scope of this disclosure. Accordingly, the scope of the present disclosure is intended to be defined only by reference to the appended claims.
Claims
1. A refiner plate, comprising:
- at least one refining zone including a first plurality of refining bars and a plurality of grooves;
- at least one groove of the plurality of grooves having a first width between adjacent refining bars of the first plurality of refining bars at an inlet of the at least one refining zone narrower than a second width along a remaining portion of the at least one groove; and
- at least one of the adjacent refining bars of the first plurality of refining bars having a widened portion in a circumferential direction of the refiner plate at an inlet portion of the at least one refining zone.
2. The refiner plate of claim 1, wherein the at least one of the adjacent refining bars has a third width at the inlet portion of the at least one refining zone wider than a fourth width of a remaining portion of the at least one of the adjacent refining bars.
3. The refiner plate of claim 2, wherein the at least one adjacent refining bar comprises a transition portion configured to transition a width of the at least one adjacent refining bar between the third width of the at least one adjacent refining bar and the fourth width of the remaining portion of the at least one adjacent refining bar.
4. The refiner plate of claim 3, wherein at least one side of the at least one adjacent refiner bar has a transition portion comprising one of a chamfer, a radius, or a step.
5. The refiner plate of claim 3, wherein both sides of the at least one adjacent refiner bar have a transition portion comprising one or a combination of a chamfer, a radius, or a step.
6. The refiner plate of claim 3, wherein the transition portion comprises an extended widened portion in a radial direction and a chamfer on both sides of the at least one refining bar.
7. The refiner plate of claim 1, wherein at least part of the widened portion of the at least one adjacent refining bar comprises a ramp rising at an angle from a substrate towards a top of the at least one refining bar.
8. The refiner plate of claim 1, wherein the at least one refining zone comprises a second plurality of refining bars, each refining bar of the second plurality of refining bars having a third width of the widened portion at the inlet portion of the at least one refining zone greater than a fourth width of the remaining portion of each of the second plurality of refining bars,
- wherein the widened portion has a first width at the inlet portion of the at least one refining zone greater than a second width in the circumferential direction of the refiner plate of a remaining portion of the at least one refining bar.
9. The refiner plate of claim 1, wherein the inlet portion of the at least one refining zone comprises a distributed refining zone inlet transition.
10. The refiner plate of claim 1, wherein widened portions of the first plurality of refining bars are staggered in a radial direction at the inlet portion of the at least one refining zone such that adjacent refiner bars have different radial distances from an inner circumference of the refiner plate to inner ends of the adjacent refiner bars.
11. The refiner plate of claim 1, wherein the refiner plate is a one-piece ring or a one-piece cone.
12. A refiner plate, comprising:
- a plurality of refiner plate segments, each refiner plate segment having: at least one refining zone including a first plurality of refining bars and a plurality of grooves; at least one groove of the plurality of grooves having a first width between adjacent refining bars of the first plurality of refining bars at an inlet of the at least one refining zone narrower than a second width along a remaining portion of the at least one groove; and at least one of the adjacent refining bars of the first plurality of refining bars having a widened portion in a circumferential direction of the refiner plate at an inlet portion of the at least one refining zone.
13. The refiner plate of claim 12, wherein the at least one of the adjacent refining bars has a third width at the inlet portion of the at least one refining zone wider than a fourth width of a remaining portion of the at least one of the adjacent refining bars.
14. The refiner plate of claim 13, wherein the at least one adjacent refining bar comprises a transition portion configured to transition a width of the at least one adjacent refining bar between the third width of the at least one adjacent refining bar and the fourth width of the remaining portion of the at least one adjacent refining bar.
15. The refiner plate of claim 14, wherein at least one side of the at least one adjacent refiner bar has a transition portion comprising one of a chamfer, a radius, or a step.
16. The refiner plate of claim 14, wherein both sides of the at least one adjacent refiner bar have a transition portion comprising one or a combination of a chamfer, a radius, or a step.
17. The refiner plate of claim 14, wherein the transition portion comprises an extended widened portion in a radial direction and a chamfer on both sides of the at least one refining bar.
18. The refiner plate of claim 12, wherein at least part of the widened portion of the at least one adjacent refining bar comprises a ramp rising at an angle from a substrate towards a top of the at least one refining bar.
19. The refiner plate of claim 12, wherein the at least one refining zone comprises a second plurality of refining bars, each refining bar of the second plurality of refining bars having a third width of the widened portion at the inlet portion of the at least one refining zone greater than a fourth width of the remaining portion of each of the second plurality of refining bars.
20. The refiner plate of claim 19, wherein widened portions of the second plurality of refining bars are staggered or distributed in a radial direction at the inlet portion of the at least one refining zone.
21. The refiner plate of claim 12, wherein the inlet portion of the at least one refining zone comprises a distributed refining zone inlet transition.
22. The refiner plate of claim 12, wherein the plurality of refiner plate segments form a ring or a cone.
Type: Application
Filed: Jan 10, 2024
Publication Date: Sep 5, 2024
Applicant: ANDRITZ INC. (Alpharetta, GA)
Inventor: Luc Gingras (Harrogate)
Application Number: 18/409,748