Refiner Segment Openings for Steam Flow and Material Retention
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Solution Overview
Problem
Existing refiner designs experience feed variations and steam flow issues during the refining process, leading to non-uniform material flow, reduced production capacity, and increased energy consumption due to the obstruction of steam by dams, which causes blockages and instability in the refining gap.
Innovation Solution
The refiner segment design features bars and dams with strategically placed openings at the borders between refining zones, allowing back-streaming steam to flow inward while preventing unprocessed material from escaping, and allows for individual adjustment of bar and groove angles and widths for each zone to optimize energy consumption and fiber quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dams are inserted in the grooves to prevent unprocessed material from passing out, then material retention is improved, but steam flow is obstructed causing feed variations and instability
Solution Approach 1:
The refiner segment is divided into multiple refining zones with different bar configurations. Each zone can be independently optimized for its specific function (coarse refining, fine refining, pitch removal), allowing simultaneous achievement of material retention and steam flow management without requiring dams that obstruct steam
Solution Approach 2:
Different zones of the refiner segment have different bar patterns, angles, and groove configurations tailored to local requirements. The inner zone has coarser bars for initial refining while outer zones have finer bars for quality refinement, enabling zone-specific optimization of both material retention and steam flow characteristics
2Productivity
If dams are used to guide material to refining space, then refining efficiency is improved, but steam flow is disturbed causing blockages and energy increase
Solution Approach 1:
The harmful function of dams (steam obstruction) is removed entirely. Instead, the patent uses strategically designed bar configurations and groove patterns that naturally guide material to the refining space between refiner discs without requiring dams, thereby eliminating steam flow disturbance and associated energy penalties
Solution Approach 2:
The bar-groove structure serves as an intermediary that performs dual functions: guiding material flow to the refining gap while simultaneously providing steam flow paths through the grooves. This eliminates the need for separate dams and resolves the conflict between material guidance and steam flow
3Speed
If bar angles are increased to enhance feeding effect, then material transport is improved, but steam flow control is reduced
Solution Approach 1:
The bar angles are varied dynamically across different zones rather than being uniform. Inner zones have larger bar angles for aggressive material transport, while outer zones have smaller angles for refined control. This zoned angular variation allows simultaneous optimization of material transport speed and steam flow control in different regions
Solution Approach 2:
Multiple parameters (bar angle, bar width, groove width, groove depth) are varied across different zones to achieve zone-specific optimization. The bar angle parameter is specifically changed from inner to outer zones to balance material transport requirements with steam flow management needs in each region
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 reduces feed conflicts and turbulence, prevents pitch build-up, and enhances the stability of the refining gap, leading to improved specific energy consumption, fiber quality, and extended segment lifetime without compromising defibration capability.
Implementation Method 1
The material is then forced by the centrifugal force towards the circumference of the discs to emerge in the refining space/gap
Implementation Method 2
The openings are configured to allow back-streaming steam to flow along the bars and dams and pass through the openings towards the inner edge of the refiner segment
Data Source
Figure 1~2
Figure 3a~3b
Figure 4
AI summary
A refiner segment (4) for a refiner (1) comprises refining zones (Z(x)) and is provided with a pattern of bars (10) arranged at a respective pumping feeding angle (β(x)) within a respective refining zone (Z(x)), and intermediate grooves (11) between the bars (10), and dams (12) extending between the bars (10) and protruding above the surface of the grooves (11). The dams are arranged at least at the ends of at least some of the bars (10) at the borders between the refining zones (Z(x)) such that openings (13) are formed at the borders between the refining zones (Z(x)), radially outside of the dams (12), where the openings (13) are arranged such that a respective angle (γ(x)) is formed between an imaginary line connecting the openings (13) at a radially inner border of a respective refining zone (Z(x)) and a line which is perpendicular to a radius (r) of the refiner segment (4), where the angle (γ(x)) is directed towards the inner edge of the refiner segment (4), thereby allowing steam (8) to pass through the openings (13) and flow towards an inner edge (41) of the refiner segment (4).