Structuring Belt 3D Depressions for High Bulk Tissue Pressing
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Solution Overview
Problem
Conventional tissue papermaking machines using pressing techniques struggle to produce high bulk tissue paper with sufficient thickness and absorption capacity while maintaining machine runnability, often requiring multiple press nips and resulting in web breaks or low bulk quality.
Innovation Solution
A structuring belt with a three-dimensional surface featuring depressions that prevents compaction of the tissue web during pressing, allowing for higher bulk and dryness levels comparable to TAD techniques, achieved through a non-woven or woven clothing with a web-contacting surface comprising 20-80% voids or elevations, which reduces energy consumption and avoids the need for pre-drying processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional pressing techniques are used to dewater the tissue web, then dewatering efficiency is improved, but the tissue web bulk and thickness are reduced
Solution Approach 1:
The press felt is designed with controlled porosity and pore size distribution to enable efficient water removal while maintaining web bulk. The porous structure allows water to pass through while supporting the tissue web without excessive compression, resolving the contradiction between dewatering efficiency and bulk preservation.
Solution Approach 2:
The invention changes the physical parameters of the press felt (porosity, pore size, compressibility) to optimize the pressing process. By adjusting these parameters, the system achieves effective dewatering while minimizing web compression, thereby maintaining high bulk and thickness.
2Productivity
If multiple press nips are used to achieve sufficient dewatering, then dewatering completeness is improved, but web breaks and machine runnability problems increase
Solution Approach 1:
The invention changes the parameters of a single press nip (pressure distribution, dwell time, press felt properties) to achieve dewatering completeness that previously required multiple press nips. This optimization reduces the number of press nips needed while maintaining reliable machine operation and avoiding web breaks.
Solution Approach 2:
The press felt acts as an intermediary between the press roll and the tissue web, mediating the pressing action to distribute pressure uniformly and prevent web breaks. This allows for more aggressive dewatering in a single nip without compromising web integrity or machine runnability.
3Volume of moving object
If TAD technique is used to increase tissue web bulk, then bulk and thickness are improved, but energy consumption increases
Solution Approach 1:
The invention replaces the thermal energy-intensive TAD process with a mechanically optimized pressing system. By using a specifically designed press felt with controlled porosity and compressibility, the system achieves high bulk tissue paper through mechanical pressing alone, eliminating the need for additional thermal drying energy input.
Solution Approach 2:
The invention changes the pressing parameters (pressure, dwell time, press felt properties) to achieve bulk levels previously only attainable through TAD. This parameter optimization allows mechanical pressing to substitute for thermal processing, significantly reducing energy consumption while maintaining high bulk and thickness.
4Productivity
If uniform compression is applied in conventional press rolls, then dewatering efficiency is improved, but web bulk and softness are reduced
Solution Approach 1:
The invention changes the compression parameters by using a compressible press felt that distributes pressure uniformly across the web. This uniform pressure distribution achieves efficient dewatering while preventing localized over-compression that would reduce web bulk and softness, resolving the contradiction between dewatering efficiency and bulk preservation.
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
The solution enables the production of tissue paper with a bulk of 12-20 cm3/g at a lower energy cost, reducing drying capacity needs by 20-35% and enhancing absorption capacity and softness, while avoiding web breaks and improving machine runnability.
Implementation Method 1
the structuring layer has a web-carrying side with a surface for cooperating with the fibrous web, said surface having depressions forming a three-dimensional structure of the surface
Implementation Method 2
pressing in a press section of a tissue papermaking machine
Implementation Method 3
said surface having depressions forming a three-dimensional structure of the surface
Data Source
AI summary
A structuring layer of a structuring belt for structuring a wet fibrous web in a press section of a tissue papermaking machine for manufacturing high bulk tissue paper, the structuring layer having a web-carrying side with a surface for cooperating with the fibrous web, the surface having depressions distributed over the web-carrying side and forming a three-dimensional structure of the surface. The depressions altogether constitute 20-80% of the surface. Each depression has a dimension l of 0.25-2.5 mm in a first direction in the plane of the top surface area, a dimension b of 0.25-2.0 mm in a second direction in the plane of the top surface area, such directions being at right angles to each other, a mean depth d of 0.05-0.6 mm, and an area a as measured in the plane of the top surface area of 0.063-5.0 mm2.