Variable-Height Refiner Bars for Wood Fiber Deflaking
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Solution Overview
Problem
Existing disc-type refiners struggle with the formation of fiber bundles during the refining process, which can lead to issues such as reduced tensile strength in paper products, clogging of downstream components, and inefficient drainage, necessitating additional processing steps like deflaking in separate refiners, increasing cost and complexity.
Innovation Solution
The use of refining members with refiner bars of varying heights and configurations, including second refiner bars with reduced maximum height and sloped designs, to transition from refining to deflaking within a single refiner, allowing for simultaneous refining and deflaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional disc-type refiners with uniform refiner bars are used, then the refining process can be performed, but fiber bundles form during processing which reduces tensile strength and causes downstream clogging
Solution Approach 1:
The refiner bars are designed with varying heights along their length, creating different local refining intensities. Shorter refiner bars in certain zones reduce excessive cutting action that causes fiber bundling, while longer bars in other zones maintain effective refining. This local variation in bar height allows the system to perform refining without generating harmful fiber bundles.
Solution Approach 2:
The refiner surface is segmented into multiple zones with different bar height characteristics. The refiner bars are divided into first, second, third, and fourth bars with progressively different heights, creating distinct refining zones. This segmentation allows different portions of the refiner to perform different functions - some areas for intensive refining, others for gentler processing that prevents bundling.
2Object-generated harmful factors
If additional separate deflaking refiners are used to break up fiber bundles, then fiber quality improves, but processing cost and system complexity increase
Solution Approach 1:
The refining and deflaking functions are merged into a single refiner unit. By incorporating refiner bars of varying heights within one refiner, the system performs both refining (fiber separation) and deflaking (bundle breaking) operations simultaneously. This eliminates the need for separate deflaking refiners, reducing system complexity while maintaining fiber quality.
Solution Approach 2:
The single refiner unit is designed to perform multiple functions - both refining and deflaking. The varied refiner bar heights enable the same refiner to handle different processing needs: intensive refining in some zones and gentle deflaking in others, making the unit universal and eliminating the need for multiple specialized devices.
3Manufacturing precision
If intensive refining is applied to all areas, then fiber separation is improved, but fiber bundles are created requiring additional deflaking steps
Solution Approach 1:
Different zones of the refiner apply different refining intensities through varied bar heights. Areas requiring intensive fiber separation use longer refiner bars, while zones prone to bundling use shorter bars for gentler processing. This local quality variation ensures high fiber separation quality without creating excessive bundles.
Solution Approach 2:
The refiner bar height parameter is varied across different zones of the refiner surface. By changing this geometric parameter, the system adjusts the refining intensity locally - taller bars provide more cutting action for separation, while shorter bars reduce intensity to prevent bundling, thus controlling the harmful effects of intensive refining.
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
This approach effectively breaks up fiber bundles during refining, reducing the need for additional deflaking steps, enhancing the quality of paper products and simplifying the processing by integrating refining and deflaking functions in a single unit.
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 second refiner bars are adapted to break up fiber bundles.
Data Source
AI summary
A refining member for a pulp refiner comprising a refining body with a refining surface comprising refiner bars separated by refiner grooves and teeth. Each of the refiner bars extend from a radially inward position on the refining surface to a first radially outward position on the refining surface, and the teeth extend to a second radially outward position on the refining surface. The second radially outward position is nearer to an outermost part of the refining body than the first radially outward position. The refiner bars are adapted to refine wood fibers, and the teeth are adapted to break up fiber bundles.