Wood Chipper Load Angle for Refining Energy Reduction
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Solution Overview
Problem
Current wood chipping technologies for pulp production face high energy consumption and high investment costs, with existing methods either increasing process complexity or not effectively reducing energy usage during the refining stage.
Innovation Solution
The use of wood chipping tools angled between 75° to 105°, preferably 80° to 100°, to direct compressive forces along the fibre direction, allowing for significant cracking and opening of the wood structure during chipping, thereby reducing energy consumption in subsequent refining stages without increasing chipping energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chipping tools with small load angles are used to minimize compression damage, then chip quality for chemical pulps is improved, but energy consumption during refining remains high
Solution Approach 1:
The invention changes the load angle parameter from conventional small angles (e.g., 3° clearance angle) to large angles (75°-105°). This parameter change fundamentally alters the chipping mechanism from minimizing compression to creating controlled compression that opens the wood structure, thereby reducing subsequent refining energy consumption by 20-40% while maintaining pulp quality
Solution Approach 2:
The invention converts the traditionally harmful compression damage into a beneficial pre-treatment effect. By intentionally applying large compressive forces during chipping at 75°-105° load angles, the wood structure is opened and prepared for easier defibration, transforming what was considered a defect into a useful pre-processing function that reduces energy consumption in later stages
2Use of energy by moving object
If compression screws or RT Pressafiner are used to compress chips before refining, then energy consumption during refining is reduced, but process complexity and capital costs increase
Solution Approach 1:
The invention extracts the compression function from separate dedicated equipment (compression screws, RT Pressafiner) and integrates it into the existing chipping process itself. By using the chipping tools at 75°-105° load angles, the compression and structural opening occurs during chipping, eliminating the need for additional compression equipment and reducing process complexity
Solution Approach 2:
The invention merges the compression function with the chipping operation. Instead of having separate chipping and compression stages, the large load angle chipping simultaneously performs cutting and compression/structural opening in one integrated process, thereby reducing capital costs and process complexity while achieving the same energy-saving effect
3Use of energy by moving object
If roll nip compression is used to compress chips, then energy consumption during refining is reduced, but chips are compressed at right angle to fibre direction which is less effective
Solution Approach 1:
The invention applies compression locally in the fibre direction through the chipping process itself, rather than applying generic compression in random or perpendicular directions. The 75°-105° load angle ensures compressive forces are directed along the fibre orientation, creating optimal structural opening where it is most needed for subsequent defibration
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 results in a substantial reduction of energy consumption during defibration and development of wood fibers, enhancing chemical impregnation and pulp production capacity without additional capital investments, while maintaining pulp quality.
Implementation Method 1
direct compressive forces along the fibre direction, allowing for significant cracking and opening of the wood structure during chipping
Implementation Method 2
significant cracking and opening of the wood structure
Data Source
AI summary
This patent application describes a method to produce wood chips with the intention of reducing the energy consumption in the subsequent process steps for pulp production. With the present method wood chipping is done in a wood chipper where the chipping tool (3) has an angle ? (4) within the interval of 75 ° to 105 ° between the fibre direction of the log and the side of the tool which faces the chip (2). Angles in this interval will cause an axially directed compression of the chip which will cause a cracking of the wood during chipping.