Refiner Bar Height Zoning for Wood Fiber Bundle Breakup
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Solution Overview
Problem
Existing disc-type refiners struggle with efficiently refining wood fibers and breaking up fiber bundles, leading to issues such as reduced tensile strength in paper products, clogging, and increased costs due to separate deflaking processes.
Innovation Solution
The use of refining members with refiner bars of varying heights and configurations, including second refiner bars with a reduced maximum height to break up fiber bundles, integrated within a single refiner to perform both refining and deflaking operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional disc-type refiners use uniform refiner bars for refining wood fibers, then the refining process can be performed, but fiber bundles are not effectively broken up leading to reduced tensile strength and clogging issues
Solution Approach 1:
The refiner bars are designed with varying heights along their length, creating different local zones with distinct functions. The taller bars perform intensive refining while the shorter bars provide gentler action for separating fiber bundles, allowing each local region to optimize its specific function rather than using uniform bars throughout
Solution Approach 2:
The refiner bar surface is segmented into multiple height levels, dividing the refining action into distinct zones. This segmentation allows the system to handle different stages of fiber processing (intensive refining vs. gentle separation) in sequence as fibers pass through the refiner gap
2Reliability
If separate deflaking equipment is used to break up fiber bundles, then fiber bundle separation can be achieved, but equipment complexity and processing costs increase
Solution Approach 1:
The refiner integrates multiple functions into a single device by combining intensive refining bars and deflaking bars within the same refiner gap. This merging eliminates the need for separate deflaking equipment, reducing overall system complexity while maintaining effective fiber bundle separation
Solution Approach 2:
The refiner system performs multiple functions simultaneously: the taller bars provide intensive refining while the shorter bars provide deflaking action. This multi-functionality allows a single refiner unit to replace what would traditionally require separate refining and deflaking equipment
3Manufacturing precision
If intensive refining is applied to all wood fibers, then fiber refinement is improved, but fiber bundles become more compact and difficult to separate
Solution Approach 1:
As fibers pass through the refiner gap, they experience periodic variation in refining intensity due to the alternating pattern of tall and short refiner bars. This periodic action allows fibers to receive intensive refining from tall bars followed by gentler separation action from short bars, preventing excessive compacting while maintaining refinement quality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the refining process by effectively breaking up fiber bundles and reducing the need for separate deflaking steps, improving the quality and efficiency of paper production while minimizing costs and equipment complexity.
Implementation Method 1
Each of the first and second refining members include a plurality of refiner bars separated by refiner grooves, in which the refiner bars define cutting surfaces for cutting the wood fibers. During operation, at least one of the first and second refining members is rotated relative to the other, in which rotation of the cutting surfaces of the refiner bars cut wood fibers being processed in the refiner.
Implementation Method 2
The second refiner bars have a longitudinal length from about 0.6 cm to about 10 cm, in which the second radially outward position is nearer to an outermost part of the refining body than the first radially outward position. The second maximum height is at least 0.35 mm less than the first maximum height. The first refiner bars are adapted to refine wood fibers, and the second refiner bars are adapted to break up fiber bundles.
Data Source
AI summary
A refining member comprising a refining body with a refining surface comprising first and second refiner bars separated by first and second refiner grooves, respectively. The first refiner bars extend from a radially inward position to a first radially outward position. The second refiner bars extend to a second radially outward position that is nearer to an outermost part of the refining body than the first radially outward position. The second refiner bars have a longitudinal length from about 0.6 cm to about 10 cm. The first and second refiner bars have a respective first and second maximum height extending upward from a floor of a respective, adjacent first or second refiner groove. The second maximum height is at least 0.35 mm less than the first maximum height. The first refiner bars are adapted to refine wood fibers and the second refiner bars are adapted to break up fiber bundles.