Variable-Curvature Forming Roll for Early Fiber Web Dewatering
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Solution Overview
Problem
Existing fiber web production methods face challenges in achieving high-quality end-products with efficient water removal while minimizing energy consumption and utilizing cost-effective raw materials without compromising strength properties.
Innovation Solution
Incorporating a variable-curvature roll as the first water removal means in the forming unit, allowing for low flow rates and high headbox consistency, which significantly reduces energy consumption and enhances water removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional water removal means are used in the forming unit, then water removal capacity is achieved, but energy consumption increases and product quality may be compromised
Solution Approach 1:
The variable-curvature roll is positioned as the first water removal means in the forming unit, performing preliminary dewatering on the fiber suspension immediately after it leaves the headbox. This preliminary action removes a significant portion of water before the web enters the main forming section, reducing the energy burden on subsequent dewatering devices while maintaining overall water removal capacity
Solution Approach 2:
The variable-curvature roll changes its curvature radius during operation to optimize dewatering performance. By varying the curvature parameter, the roll can adapt to different fiber suspension conditions and achieve effective water removal at lower energy consumption compared to fixed-curvature rolls or conventional dewatering devices
2Use of energy by moving object
If high flow rates are used in the headbox, then fiber web production speed is maintained, but energy consumption increases
Solution Approach 1:
The variable-curvature roll performs preliminary dewatering before the fiber web enters the main forming section, allowing the headbox to operate at lower flow rates. By removing water early in the process, the system can reduce headbox flow rate and associated energy consumption while still achieving the required production speed through efficient subsequent dewatering stages
3Productivity
If multiple water removal devices are arranged in sequence, then water removal efficiency is improved, but device complexity increases
Solution Approach 1:
The variable-curvature roll serves multiple functions: it acts as the first water removal means, performs preliminary dewatering, and can be adjusted to handle different fiber suspension conditions. This multi-functionality reduces the need for additional specialized devices, simplifying the overall forming unit structure while maintaining high water removal efficiency
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 method achieves substantial energy savings and effective water removal with reduced energy needs, maintaining product quality and strength properties, and enabling the use of cost-effective raw materials.
Implementation Method 1
increasing dewatering pressure is applied to the stock suspension travelling between the wires on said at least one curvilinear dewatering zone, which increasing dewatering pressure is dependent on a tension of the wires and a radius of curvature of said at least one curvilinear dewatering zone
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a method for forming a fiber web (W) in a forming section comprising a headbox (30) and a forming unit (110), in which method fiber suspension is fed from the headbox (30) to the forming unit (110) comprising at least a twin-wire part comprising a bottom wire (10) and a top wire (20). In the method water is removed from the fiber suspension in the beginning of the forming unit (110) by at least one variable-curvature roll (15; 15A, 15B) comprising a belt loop (53), which variable-curvature roll (15; 15A, 15B) has at least two partial curves such that the radius of curvature of a first partial curve in the first zone (A1) is bigger than the radius of curvature of a second partial curve in the second zone (A2) following the first partial curve in the travel direction of the belt loop (53).). The invention also relates to a forming section for forming a fiber web (W), which forming section comprises a headbox (30) and a forming unit (110) comprising at least a twin-wire part comprising a bottom wire (10) and a top wire (20). In the beginning of the forming unit (110) at least one variable-curvature roll (15; 15A, 15B) comprising a belt loop (53), which variable-curvature roll (15; 15A, 15B) has at least two partial curves such that the radius of curvature of a first partial curve in the first zone (A1) is bigger than the radius of curvature of a second partial curve in the second zone (A2) following the first partial curve in the travel direction of the belt loop (53).