Impingement Dryer Edge Control Strip for Web Runnability
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Solution Overview
Problem
Impingement dryers face runnability issues due to air flows, leading to edge defects and web breaks, especially when using unsupported draw, as the hot air blowing can detach the paper web from the support fabric and cause inadequate drying of edge areas.
Innovation Solution
The implementation of movable edge control strips to control the effect of gas blowing and exhaust means along the machine direction edges of the impingement dryer, allowing for precise adjustment of air flows to prevent edge detachment and improve drying quality, even during unsupported draw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hot air is blown toward the paper web to dry it, then drying efficiency is improved, but air flows can lift the edge of the web off the support fabric causing edge defects and web breaks
Solution Approach 1:
The patent applies dynamics by making the blow surface movable in the machine direction. The blow surface can be adjusted to different positions to optimize the blowing effect for different web widths and to prevent edge lifting. This dynamic adjustment allows the system to adapt to changing conditions and maintain both high drying efficiency and reliable web runnability.
Solution Approach 2:
The patent changes the position parameter of the blow surface in the machine direction. By adjusting the blow surface position, the system can control the air flow distribution to match different web widths and prevent excessive blowing at the edges, thereby avoiding web detachment while maintaining effective drying.
2Area of stationary object
If the blow extends over the edge of the web, then drying coverage is improved, but the support fabric temperature can rise beyond safe limits
Solution Approach 1:
The movable blow surface allows dynamic adjustment of the blowing area. The system can extend the blow zone to cover edge areas for improved drying coverage while simultaneously adjusting the position to prevent excessive concentration of hot air on the support fabric, thereby controlling temperature within safe limits.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the blow surface position to control the spatial distribution of hot air. This allows optimization of the balance between drying coverage area and support fabric temperature exposure, preventing thermal damage while maintaining effective drying.
3Adaptability or versatility
If the web width is changed to accommodate different paper grades, then product versatility is improved, but the blows need to be readjusted to the correct area
Solution Approach 1:
The movable blow surface enables the system to adapt to different web widths dynamically. When web width changes due to paper grade variations, the blow surface can be repositioned to match the new web dimensions, eliminating the need for complex readjustment procedures and reducing operational complexity.
Solution Approach 2:
The patent applies parameter changes by allowing the blow surface position to be adjusted according to web width. This simple parameter adjustment enables the system to handle different paper grades and web widths without requiring complex system reconfiguration, thereby improving versatility while maintaining operational simplicity.
4Reliability
If a too narrow blow zone is used, then edge detachment is prevented, but insufficient drying occurs at the edge areas
Solution Approach 1:
The dynamic blow surface position adjustment allows the system to optimize the blow zone width for each specific web width. By extending the blow zone appropriately for different web dimensions, the system ensures sufficient edge drying while preventing detachment, achieving both reliable edge attachment and high edge drying quality simultaneously.
Solution Approach 2:
The patent utilizes parameter changes in blow surface position to control the effective blow zone width. This adjustment enables optimization of the balance between preventing edge detachment and ensuring adequate edge drying, allowing the system to adapt to different web widths and maintain optimal drying quality.
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 reduces runnability problems, minimizes edge defects, and enhances the drying quality of edge areas by ensuring controlled air flow distribution, thereby preventing web breaks and improving the overall drying process.
Implementation Method 1
The fibre web to be dried is supported with a support fabric... Hot gas, for example air, is blown from the blowing means toward the fibre web to be dried
Implementation Method 2
Hot gas, for example air, is blown from the blowing means toward the fibre web to be dried
Implementation Method 3
The gas is removed from the vicinity of the fibre web to the exhaust means... air exhaust means for removing air from the dryer
Data Source
Figure 1
Figure 2
Figure 3A~4B
AI summary
The invention relates to an impingement dryer (10, 20, 30) and a method for reducing runnability problems caused by gas flows in an impingement dryer (10, 20, 30) for a fibre web, which impingement dryer has gas blowing means (104) and gas exhaust means (105). In the method according to the invention the fibre web (50) to be dried is supported with a support fabric (51-53). The support fabric (51-53) and the fibre web (50) to be dried are moved in the machine direction inside the impingement dryer past the blowing means (104) and exhaust means (105). At the same time hot gas is blown from the blowing means (104) toward the fibre web (50) to be dried and gas is removed from the vicinity of the fibre web (50) to the exhaust means (105). At least one edge control strip (201) is moved in the machine direction edges (71) of the impingement dryer (10, 20, 30) in front of the blowing means (104) or the exhaust means (105) or both. With its aid a desired number of blowing means (104) or exhaust means (105) or both are covered and thus their effect is controlled.