Air Dryer Profiling for Paper Web Moisture Control
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Solution Overview
Problem
Existing drying technologies for paper and board webs, such as infrared and air dryers, face challenges in achieving uniform moisture profiles, leading to runnability issues and high energy inefficiency, with infrared dryers being expensive and requiring frequent maintenance, and air dryers unable to correct transverse moisture defects effectively.
Innovation Solution
An air dryer arrangement with a profiling connection that supplies additional air into second air supply channels to alter the temperature and moisture profile of the web in the transverse direction, allowing for precise control of moisture profiling without increasing maintenance or investment costs, using energy-efficient thermal convection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If infrared dryers are used for drying paper webs, then drying can be performed contact-free with some moisture profiling capability, but the operation costs are high due to poor energy efficiency and expensive maintenance is required
Solution Approach 1:
The patent replaces infrared radiation-based drying with a mechanical air flow system that uses heated air convection. Instead of using infrared lamps or gas infrared emitters, the invention employs a network of air channels and blow nozzles that deliver heated air to the paper web surface, achieving drying through thermal convection rather than thermal radiation. This substitution dramatically improves energy efficiency while eliminating maintenance issues associated with infrared components
Solution Approach 2:
The invention uses a pneumatic system consisting of air channels, blow nozzles, and controlled air flow to deliver heated air to the paper web. The air dryer comprises a housing with first air channels for distributing heated air and second air channels with blow nozzles for targeted moisture profiling. This pneumatic approach enables precise control of air flow patterns and moisture removal while maintaining high energy efficiency
2Reliability
If infrared dryers are used for drying paper webs, then drying can be performed, but the temperature of the web may easily rise too high causing potential damage
Solution Approach 1:
The patent implements local quality control by dividing the drying system into multiple zones with independent air flow control. The air dryer comprises first air channels for general heating and second air channels with blow nozzles for localized moisture profiling. This allows different regions of the paper web to receive customized air flow and heating, preventing localized overheating while achieving uniform overall drying. The profiling capability enables precise temperature and moisture control in specific transverse zones
3Use of energy by moving object
If conventional air dryers are used for drying paper webs, then energy efficiency is high, but it has not been possible to use them for correcting moisture defects in the transversal direction of the web
Solution Approach 1:
The patent segments the air drying system into multiple independent air channels and blow nozzles distributed across the width of the paper web. The air dryer comprises first air channels for overall heating and second air channels with individually controllable blow nozzles for transverse moisture profiling. This segmentation allows each zone to be controlled independently, enabling precise correction of moisture defects in specific transverse regions while maintaining high energy efficiency through the air convection mechanism
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 effective equalization of moisture profiles with local variations of up to 0.5% moisture, reducing energy consumption, maintaining consistent pressure, and avoiding runnability problems while being cost-effective and simple to maintain.
Implementation Method 1
The operation of the air dryer is based on convection, i.e. on the transfer of heat via a medium. In an air dryer heated air is blown with blow nozzles toward the surface of the web in order to dry it.
Implementation Method 2
heated air is blown with blow nozzles toward the surface of the web in order to dry it
Implementation Method 3
In infrared dryers the web is dried in a contact-free manner by subjecting it to thermal radiation
Data Source
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AI summary
The invention relates to a drying arrangement and method for a moving web, such as a paper or board web. The arrangement comprises an air dryer (3, 3',3'',3'''), which comprises a first air supply channel (9), which defines a first direction and which extends in a transversal direction of the web to be dried from its first edge toward its second edge. The air dryer also comprises a number of second air supply channels (12), which are arranged in connection with the first air supply channel (9), and into which heated drying air is supplied from the first air supply channel (9), the second air supply channels (12) defining a second direction, which is perpendicular to the first direction and parallel to the travel direction of the web to be dried. The air dryer further comprises elongated blowing means (13, 13', 13''), each of which is arranged in connection with a plurality of second air supply channels (12) for supplying heated drying air from the second air supply channels (2) to the blowing means (13, 13', 13''), the blowing means (13, 13', 13'') being parallel to the first air supply channel (9). A profiling connection (7) has been arranged in connection with at least one, preferably several, second air supply channels (12) for supplying additional air into the second air supply channel (12) in order to change the moisture profile of the web in the transversal direction of the web.