Yankee Cylinder Coating Control for Tissue Web Transfer
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Solution Overview
Problem
Tissue web breakage during production in tissue machines due to high bulk content, particularly during transfer onto and take-off from the Yankee cylinder, is exacerbated by the narrow operating window required for adherence and release, which is influenced by the temperature profile and thickness of the Performance Enhancing Material (PEM) coating.
Innovation Solution
Implementing a moisture-controlled environment between the take-off and transfer positions on the Yankee cylinder with reduced relative humidity and enhanced evaporation rates to prevent the PEM coating from overheating, maintaining tackiness and reducing viscosity, thereby improving web transfer and take-off efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PEM coating is applied on the Yankee cylinder to improve transfer and take-off, then the adherence and release are improved, but the coating overheats and becomes glassy, reducing tackiness and increasing web breakage
Solution Approach 1:
The patent applies a cooling action before the PEM coating reaches the overheating stage by introducing a cooling zone with cooled air or coolant before the application position. This preliminary cooling prevents the coating from overheating and becoming glassy, maintaining its tackiness and improving web transfer reliability.
Solution Approach 2:
The patent introduces a cooling medium (cooled air or coolant) as an intermediary between the hot Yankee cylinder surface and the PEM coating. This intermediary absorbs excess heat from the coating, preventing direct thermal contact and avoiding the glassy state while maintaining the beneficial thermal properties for web transfer.
2Reliability
If the PEM coating thickness is increased to improve adherence, then the tackiness is improved, but the coating consumes more material and the operating window becomes narrower
Solution Approach 1:
The patent changes the temperature parameter of the PEM coating by introducing cooling before application. This temperature control allows for optimized coating thickness - thinner coatings can achieve adequate adherence when properly cooled, reducing PEM consumption while maintaining reliability. The cooling modifies the coating's physical state to enhance its adhesive properties without requiring excessive thickness.
3Productivity
If the Yankee cylinder speed is increased to improve productivity, then the production capacity increases, but the web breakage during transfer and take-off increases
Solution Approach 1:
The patent applies cooling before the PEM coating reaches the transfer position, preparing the coating in advance to maintain its tackiness at higher speeds. This preliminary cooling action enables the coating to withstand increased web speeds without losing adhesive properties, thereby supporting higher productivity while maintaining transfer reliability.
Solution Approach 2:
The patent modifies the temperature parameter of the PEM coating through cooling before application. This temperature control allows the coating to maintain optimal viscosity and tackiness at higher web speeds, enabling increased production capacity without compromising web transfer reliability. The cooled coating resists overheating that would otherwise occur at higher speeds.
4Reliability
If the PEM coating is applied to improve take-off, then the release is improved, but the coating viscosity changes and application becomes less even
Solution Approach 1:
The patent introduces cooling before the PEM coating application to prevent premature viscosity changes. By cooling the coating area before application, the coating maintains more consistent viscosity throughout the application process, resulting in more uniform coating thickness and better take-off performance.
Solution Approach 2:
The cooling medium acts as an intermediary that stabilizes the coating's physical properties during application. This intermediary prevents rapid viscosity changes that would occur on the hot Yankee surface, allowing for more even coating distribution and improving both uniformity and take-off reliability.
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 increases the operating window for successful transfer and take-off at higher speeds, reduces web breakage, and optimizes the application of the PEM coating, leading to more even diameter in the take-up roll and lower consumption of the PEM, thus enhancing production capacity and hygiene.
Implementation Method 1
cooling the surface of the Yankee cylinder in the moisture-controlled environment by increasing evaporation rate of water in or applied onto the Performance enhancing material
Data Source
AI summary
The invention relates to a method and system for improving the application of a coating on a Yankee cylinder (CR) in tissue paper machines. The invention implements a moisture-controlled environment (12) in an area of the exposed Yankee cylinder between the take-off position (TO) and ahead of the transfer position (TP) of the web, i.e. before and/or after the application of a coating with Performance Enhancing Material (PEM), wherein the cooling effect on the Yankee surface is increased by increased evaporation rate of water in the coating or water additionally applied onto the coating.