Variable Height Refiner Bars for Pulp Deflaking

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Solution Overview

Problem

Conventional pulp refiners require separate deflaking processes to break up fiber bundles, increasing complexity and cost, and can degrade pulp properties when processing different slurries.

Innovation Solution

A pulp refiner design with refining members featuring refiner bars of varying heights, where the first bars refine wood fibers and the second bars, with a minimum height difference, break up fiber bundles within a single refiner, transitioning from refining to deflaking zones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate deflaking processes are used to break up fiber bundles, then fiber bundles are effectively broken, but process complexity and cost increase

Engineering Contradiction:

Improveprocess complexityVSAvoidnumber of processing units

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent combines refining and deflaking functions into a single refiner unit by incorporating two different refiner bar configurations: first refiner bars with a first height for refining, and second refiner bars with a second height (at least 0.35mm less than the first height) for deflaking. This merging eliminates the need for separate deflaking processes and reduces overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The refiner member is designed with multi-functionality by including both refining and deflaking capabilities in one unit. The first refiner bars perform traditional refining operations, while the second refiner bars with reduced height perform deflaking operations, allowing a single device to execute multiple processing functions that traditionally required separate equipment.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If conventional refiners process different slurries, then production flexibility is maintained, but pulp properties are degraded

Engineering Contradiction:

Improvepulp qualityVSAvoidpulp property consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The refiner member applies local quality by having different refiner bar heights in specific zones: the first refiner bars (taller) are positioned for refining operations, while the second refiner bars (shorter by at least 0.35mm) are positioned for deflaking operations. This spatial differentiation of bar heights allows the system to process different slurry types while maintaining consistent pulp properties through zone-specific processing.

Inventive Principle:

Principle #3Local quality

3Productivity

If refiner bars have varying heights, then both refining and deflaking occur in single unit, but manufacturing complexity increases

Engineering Contradiction:

Improveprocessing efficiencyVSAvoidrefiner bar configuration

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The refiner member is segmented into different functional zones with distinct refiner bar heights. The first refiner bars with the first height handle refining, while the second refiner bars with the second height (at least 0.35mm less) handle deflaking. This segmentation of the refiner surface into zones with different bar heights enables simultaneous refining and deflaking operations, improving productivity despite increased manufacturing complexity.

Inventive Principle:

Principle #1Segmentation

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 design enables efficient refinement and deflaking within a single unit, reducing process complexity and maintaining pulp quality by controlling the gap between refiner bars to manage refining and deflaking forces effectively.

Implementation Method 1

rotation of the cutting surfaces of the refiner bars cut wood fibers being processed in the refiner

Methodology Applied

Scientific EffectMechanical shearing: Shear Stress

Implementation Method 2

The second height is a minimum height of the second refiner bars and is spaced apart from the second radially inward position, with the second height being at least about 0.35 mm less than the first height

Methodology Applied

Scientific EffectMechanical force differential: Force

Data Source

PatentUS20240295076A1Apparatus and method for processing wood fibers

Publication Date: 2024.09.05 INT PAPER CO

AI summary

A refining member including a refining body with a refining surface including first and second refiner bars separated by first and second refiner grooves. The first and second refiner bars extend from respective first and second radially inward positions to respective first and second radially outward positions. The first and second refiner bars have a respective first and second height extending upward from a floor of a respective, adjacent first or second refiner groove. The second height is a minimum height of the second refiner bars and is spaced apart from the second radially inward position, with the second height being at least about 0.35 mm less than the first height. The first refiner bars are adapted to refine wood fibers and the second refiner bars are adapted to break up fiber bundles.