Press Roll Sensor Network for Tissue Web Monitoring
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Solution Overview
Problem
Monitoring pressure and temperature profiles in the nip of Yankee drying cylinders during tissue paper production is challenging due to deformations caused by operational influences, leading to uneven moisture and thickness issues in the fibrous web, which can result in web breaks and unsatisfactory product quality.
Innovation Solution
The implementation of pressure and/or temperature sensors spaced differently across the cross-machine direction of the press roll, with fiber Bragg gratings on optical waveguides arranged to optimize deformation measurement, ensuring close monitoring of critical edge areas and providing a dense sensor network for accurate data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure and temperature sensors are uniformly distributed across the press roll, then the sensor network is simple to implement, but the monitoring precision in critical edge areas is insufficient
Solution Approach 1:
The patent applies local quality by implementing non-uniform sensor distribution where sensors in peripheral regions (edge areas) are spaced more closely together than sensors in central regions. This creates locally optimized monitoring density matched to the specific needs of different roll areas, with higher precision in edge regions where deformations are most critical.
2Measurement precision
If fiber Bragg gratings are arranged at large angles with the circumferential direction, then the sensor coverage area is increased, but the deformation measurement accuracy decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the angular orientation parameter of fiber Bragg gratings relative to the circumferential direction. The gratings are arranged at specific angles that balance measurement accuracy with coverage requirements, ensuring optimal deformation detection capability while maintaining adequate spatial coverage of the press roll surface.
3Measurement precision
If sensors are arranged to closely monitor peripheral regions, then edge area monitoring precision is improved, but the overall device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the press roll surface into distinct zones (central and peripheral regions) and applying different sensor densities to each zone. This segmented approach allows high-precision monitoring in critical edge areas while using lower density in less critical central areas, thereby managing overall system complexity.
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 solution enables continuous and accurate monitoring of pressure and temperature conditions in the nip, preventing overpressing and ensuring consistent web thickness, thus improving the quality and uniformity of the fibrous web production.
Implementation Method 1
Fiber Bragg gratings are optical interference filters arranged in optical waveguides, which are written into the optical waveguide by means of a laser, for example. Wavelengths that are within the specified filter bandwidth around λ B are reflected.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a machine (1) for producing and/or processing a fiber web (2), in particular a tissue web, comprising a press roll (6) and a counter roll (3), which forms a roll gap (7) together with the press roll (6) and the lateral surface of which has a contour that runs in the machine transverse direction. The contour changes during the operation of the machine (1) in comparison to when the machine (1) is at rest. The press roll (6) has a roll core (9) and a roll cover (10) which surrounds the roll core (9). Multiple pressure and/or temperature sensors (11) are arranged in the roll cover (10) and/or between the roll core (9) and the roll cover (10). The pressure and/or temperature sensors (11) are arranged at different distances from one another in the machine transverse direction of the press roll (6) at least in some regions.