Refining Segment Deflector Arrangement for Pulp Flow Distribution
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Solution Overview
Problem
In disc-type refiner apparatuses, the transition from less dense to denser bar patterns leads to uneven fibrous material flow, causing excessive wear on fine refining bars due to concentration of flow, particularly in board pulp processing where pattern density changes are significant.
Innovation Solution
The introduction of a deflector arrangement on coarse bars, protruding from the bar surface facing the rotational direction, directs the fibrous material flow away from the bar surface, spreading it more evenly over the transition region between different bar pattern densities, reducing wear on fine bars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bar pattern density increases from the first portion to the second portion in radial direction, then the refining effectiveness is improved, but the wear concentration on fine bars increases due to flow following the coarse bar sides
Solution Approach 1:
The deflector arrangement acts as an intermediary element between the coarse bars of the first portion and the fine bars of the second portion. It intercepts the fibrous material flow that would otherwise follow the coarse bar sides and redirect it towards the fine bars, distributing the flow more evenly across the transition region and reducing wear concentration on any single fine bar.
Solution Approach 2:
The deflector arrangement is specifically positioned at the transition region where the bar pattern density changes. It provides localized flow redirection only where needed - at the interface between coarse and fine bars - without affecting the refining effectiveness in either the first or second portion independently. This localized intervention addresses the wear problem without compromising overall refining performance.
2Productivity
If the bar pattern density changes significantly between portions, then the refining capability is improved, but the flow concentration on fine bars in front of coarse bar ends increases causing excessive wear
Solution Approach 1:
The deflector arrangement is positioned upstream in the flow path, before the fibrous material reaches the fine bars. It preliminarily redirects the flow direction at the transition region, preventing the concentration effect from occurring in the first place rather than trying to mitigate it after the fact. This preliminary intervention preserves fine bar service life while maintaining refining capability.
3Use of energy by moving object
If the refining segment structure is made thinner to reduce weight, then the energy consumption is reduced, but the frequency of replacement increases due to higher wear on fine bars
Solution Approach 1:
The deflector arrangement converts the potentially harmful flow concentration effect into a beneficial even distribution pattern. By redirecting the flow that would naturally concentrate on fine bars, it transforms a wear-causing mechanism into a flow-distributing mechanism, allowing the use of thinner, more energy-efficient structures without the penalty of frequent replacements.
Data Source
Figure 1
Figure 2~4
AI summary
A refining segment (24), intended for refiners of disc-type for working fibrous material, comprises a first portion (40) having a first pattern of coarse bars (44) and a second portion (42) having a second pattern of fine bars (46). The second portion (42) is positioned outside the first portion (40). The second pattern has a higher density of bars (46) than the first pattern. The refining segment (24) further comprises a deflector arrangement (50), protruding from a bar surface (43) of the coarse bar (44). The bar surface (43) is the one facing the rotational direction (60). The deflector arrangement (50) has a deflector surface (52) directing a flow of fibrous material away from the bar surface (43). Also, a refining apparatus has two opposing rotatable refining discs, separated by a refiner gap. At least one of the two refining discs comprises the above described patterns and deflector arrangements.