Paper Web Fiber Orientation via Dielectric Barrier Discharge
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Solution Overview
Problem
Conventional papermaking processes struggle to achieve uniform fiber alignment and distribution, leading to anisotropic properties and flake formations in paper, which affect its strength, evenness, and appearance.
Innovation Solution
The method involves using dielectric barrier discharges to introduce pressure waves in the wet area of paper production, causing localized energy input to reorient and redistribute paper fibers, thereby improving their alignment and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional papermaking processes are used with standard wire arrangement and high wire speed, then production efficiency is maintained, but fiber alignment becomes anisotropic with predominant alignment along the wire running direction
Solution Approach 1:
The patent applies electrical discharges that generate pressure waves and vibrations in the wet fiber layer on the wire. These mechanical vibrations disrupt the unidirectional fiber alignment caused by high wire speed, redistributing fibers more uniformly in all directions while maintaining production efficiency.
Solution Approach 2:
The patent replaces conventional mechanical fiber redistribution methods with electrical discharges. The electrical energy generates pressure waves that act on the fiber suspension, achieving isotropic fiber alignment without altering the mechanical wire operation and maintaining productivity.
2Strength
If electrical discharges are applied to reorient fibers isotropically, then tear strength transverse to the paper web is improved, but process complexity increases
Solution Approach 1:
The patent introduces pressure waves as an intermediary between the electrical discharge and the fiber layer. The electrical discharges generate pressure waves that indirectly act on the fibers to reorient them, rather than directly applying electrical force to the fibers, which simplifies the interaction mechanism.
Solution Approach 2:
The patent changes the physical state and arrangement parameters of fibers through controlled electrical discharges. By adjusting discharge parameters such as voltage, frequency, and electrode configuration, the fiber orientation distribution is modified to improve transverse tear strength while managing process complexity.
3Speed
If conventional dewatering and fiber distribution methods are used, then production speed is maintained, but flake formations occur reducing paper evenness and appearance
Solution Approach 1:
The patent uses pressure waves generated by electrical discharges to create vibrations in the wet fiber layer during dewatering. These vibrations prevent fibers from settling into concentrated flakes, maintaining even distribution while allowing rapid dewatering and production speed.
Solution Approach 2:
The patent applies periodic electrical discharges that create oscillating pressure waves in the fiber suspension. This periodic action continuously disrupts emerging flake formations, maintaining uniform fiber distribution throughout the dewatering process at high production speeds.
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 enhances the quality of the paper by achieving more isotropic fiber alignment, reducing flake formations, and improving the paper's strength and evenness, allowing for higher quality production with lower waste.
Implementation Method 1
a change or influence on the formation, i.e. the fiber alignment and distribution in the paper, through a local effect of pressure waves, which are triggered by local electrical discharges
Implementation Method 2
local electrical discharges, in the wet area of paper production
Implementation Method 3
a plasma is used to generate radicals in a paper web. These radicals lead, on the one hand, to increased bond strength between the fibers
Implementation Method 4
a plasma is used to generate radicals in a paper web
Implementation Method 5
A finite, i.e. limited, elastic recovery of the fibers leads to the area of the discharge channel largely closing again, so that no holes caused by the discharges remain in the paper web
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3
AI summary
The invention relates to a method and a device for modifying the orientation of paper fibres (3) in a paper web, as well as to a paper machine which comprises such a device. A paper web which is still damp is formed by applying an aqueous suspension of paper fibres (3) onto a wire, and at least one electrical discharge is generated through this still-damp paper web, and/or generated such that it emanates from the surface of said paper web (9).