Curved Bar Refiner Plate for Counter-Rotating Mechanical Pulping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mechanical pulping processes face inefficiencies due to high friction between wood chips and refiner plates, leading to low energy efficiency, reduced pulp strength, increased wear on refiner plates, and shorter operational life, despite efforts to reduce the operating gap between plates.
Innovation Solution
Designing refiner plates with a curved and jagged outer section that increases retention time of wood chips in the peripheral refining zone, allowing for a larger operating gap while maintaining high energy efficiency and fiber quality, and extending the life of refiner plates by concentrating energy input towards the periphery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the operating gap between refiner plates is reduced to improve energy efficiency, then energy efficiency improves, but refiner plate wear increases and operational life decreases
Solution Approach 1:
The refiner plate surface is divided into different zones with distinct bar configurations. The peripheral zone features curved bars with larger radii and optimized spacing specifically designed for high-velocity operation, while inner zones have different configurations. This local differentiation allows the peripheral region to maintain high energy efficiency without subjecting the entire plate to the wear conditions of reduced gap operation.
Solution Approach 2:
The refiner plate is segmented into multiple functional zones: an inner zone with straight bars for initial compression, a transition zone with gradually curving bars, and an outer peripheral zone with fully curved bars. This segmentation allows each zone to operate optimally at its specific radial position, enabling the peripheral zone to achieve high energy efficiency while the overall plate structure maintains durability through appropriate gap management in different regions.
2Use of energy by moving object
If the operating gap between refiner plates is reduced to improve energy efficiency, then energy efficiency improves, but fiber cutting increases and pulp strength decreases
Solution Approach 1:
Different bar configurations are applied to different radial zones of the refiner plate. The peripheral zone uses curved bars with optimized geometry that generate high compression and shear forces suitable for fiber separation without excessive cutting, while inner zones use configurations more suited for initial chip breakdown. This local optimization allows energy-efficient operation in the peripheral zone without compromising overall pulp quality.
Solution Approach 2:
The curved bar design in the peripheral zone creates dynamic compression and release cycles as material passes through the refining gap. The curvature allows for varying compression forces during the rotation cycle, providing intensive refining action during high-velocity peripheral operation while maintaining fiber integrity through controlled release phases that prevent excessive cutting.
3Use of energy by moving object
If the operating gap between refiner plates is reduced to improve energy efficiency, then energy efficiency improves, but friction increases and wear rate increases
Solution Approach 1:
The peripheral zone of the refiner plate features curved bars with specific spacing and geometry optimized for high-velocity operation with reduced friction. The curvature and spacing create a flow pattern that reduces direct rubbing and sliding friction between wood chips and plate surface, enabling energy-efficient operation without the excessive wear that would result from simply reducing the gap across the entire plate surface.
4Use of energy by moving object
If the fiber pad thickness is reduced to improve compression rate and energy efficiency, then energy efficiency improves, but refiner plate wear increases
Solution Approach 1:
The curved bar configuration in the peripheral zone creates a localized compression zone that achieves high compression rates without requiring a uniformly thin fiber pad across the entire plate. The curvature concentrates the refining action in specific areas where it is most effective, maintaining energy efficiency while reducing overall friction and wear compared to a uniform thin-pad configuration.
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 enhances energy efficiency, reduces energy consumption, preserves fiber length, and extends the operational life of refiner plates by increasing retention time and applying high compression rates without reducing the operating gap, resulting in high-quality pulp production.
Implementation Method 1
The refiner plates generally feature a pattern of bars and grooves, as well as dams, which together provide a repeated compression and shear actions on the lingo-cellulosic fiber material
Implementation Method 2
The refiner plates generally feature a pattern of bars and grooves, as well as dams, which together provide a repeated compression and shear actions on the lingo-cellulosic fiber material
Implementation Method 3
raw material, typically wood or other lignocellulosic material (collectively referred to as wood chips), is fed through the middle of one of a refiners discs and propelled outwards by a strong centrifugal force created by the rotation of one or both rotor discs
Implementation Method 4
In the mechanical pulping process, a large amount of friction occurs, such as between the wood chips and the refiner plates. This friction reduces the energy efficiency of the process
Data Source
AI summary
A refining plate segment for a mechanical refiner of lignocellulosic material including: a refining surface on a substrate, wherein the refining surface faces a refining surface of an opposing refiner plate, the refining surface including bars and grooves between the bars, wherein an angle of each bar with respect to a radial line corresponding to the bar increases at least 15 degrees along a radially outward direction, and the angle is a holdback angle in a range of 10 to 45 degrees at the periphery of the refining surface, and wherein the bars each include a leading sidewall having an irregular surface, wherein the irregular surface includes protrusions extending outwardly from the sidewall towards a sidewall on an adjacent bar and the irregular surface extends from at or near the outer periphery of the refining surface extends radially inwardly along the bars without reaching an inlet of the refining surface.