Refining Surface Blade Groove Geometry for Lignocellulose Flow
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Solution Overview
Problem
Conventional refiners for defibrating lignocellulose-containing materials face inefficiencies in material movement between refining surfaces, leading to blockages, decreased production capacity, and non-uniformity in refined material quality due to dams that restrict steam flow and cross-sectional flow area.
Innovation Solution
The refining surface features blade grooves with a substantially continuous change in depth from the blade bar's upper surface, where the distance of the bottom of the second blade groove deviates from the first blade groove by the same distance from the feed edge, promoting dynamic material movement and reducing the need for conventional dams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dams are positioned at the bottom of blade grooves to guide material between blade bars, then material guidance and refining effect are improved, but steam flow and material passage are restricted leading to blockages and decreased production capacity
Solution Approach 1:
The invention removes dams from the blade groove structure entirely. Instead of using dams to guide material, the patent relies on the natural geometry of the blade grooves and the relative motion between rotor and stator to achieve material guidance and refining, thereby eliminating the flow restriction problem caused by dams
Solution Approach 2:
Instead of using dams to force material through restricted passages, the invention inverts the approach by creating open blade grooves that naturally guide material through their geometry. The material flow is promoted by the continuous change in groove depth rather than by restrictive barriers
2Reliability
If dams are used to guide material to blade gap space, then refining effect is promoted, but cross-sectional flow area is restricted causing non-uniformity in refined material quality
Solution Approach 1:
The invention extracts dams from the system and replaces them with blade grooves having continuously changing depth. This open groove structure provides uniform material distribution across the refining surface without creating localized restrictions that would cause quality non-uniformity
Solution Approach 2:
The blade grooves are designed with locally varying depth characteristics along their length, with the depth changing continuously to optimize material flow and refining at different positions. This local variation in groove geometry ensures uniform refining effect across the entire surface
3Reliability
If dams restrict steam flow in blade grooves, then material guidance is improved, but energy consumption increases due to reduced flow efficiency
Solution Approach 1:
By removing dams entirely, the invention eliminates the flow restriction that caused energy losses. The open blade groove structure allows steam and material to flow freely while still achieving effective guidance through the groove geometry and rotor-stator interaction
Solution Approach 2:
The invention utilizes fluid dynamics principles where steam flow patterns and material suspension are optimized through the blade groove geometry. The continuously varying groove depth creates efficient flow patterns that reduce energy consumption while maintaining effective material guidance
Data Source
AI summary
A refining surface (1, 2) of a refiner for defibrating lignocellulose-containing material has a feed edge (14) and a discharge edge (15) and has a first blade groove (17a) and a second blade groove (17b), with a blade bar (16) therebetween. A distance (D, D17a, D17b) of the bottom (18) of the first blade groove (17a) and the second blade groove (17b) from an upper surface (16a) of the blade bar (16) is arranged, at least in a part, to change substantially continuously in a direction of travel (A) of the blade grooves. The distance of the bottom of the second blade groove from the upper surface of the blade bar deviates from the distance of the bottom of the first blade groove from the upper surface of the blade bar at substantially the same distance (SD) from the feed edge of the refining surface.