Evaporative Cooling for Fibrous Web Smoothing
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Solution Overview
Problem
Temperature control of fibrous webs in paper or cardboard production is challenging for optimal smoothing and rolling, leading to issues with volume-saving smoothing and surface quality.
Innovation Solution
Implementing evaporative cooling units before and after smoothing devices, with controlled steam application to maintain moisture levels and temperature stability, using cooling and heating to ensure the fibrous web's moisture content remains between 6 and 11% and temperature below 50°C, and employing heated rollers with different surface materials for effective smoothing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If evaporative cooling is used to cool the fibrous web, then the temperature is reduced effectively, but the moisture content decreases excessively
Solution Approach 1:
The patent changes the parameters of the cooling medium by introducing a water mist system that evaporates on contact with the hot web. This transforms the cooling mechanism from direct air cooling to evaporative cooling, where water vapor absorbs heat from the web while the water itself evaporates, achieving effective cooling with minimal moisture loss to the web.
Solution Approach 2:
The water mist acts as an intermediary substance between the hot fibrous web and the cooling air. The water droplets in the mist evaporate on contact with the web, transferring heat from the web to the evaporating water, thereby cooling the web without directly removing moisture from the web structure.
2Manufacturing precision
If the fibrous web is cooled to below 50°C before winding, then volume-preserving smoothing is achieved, but the cooling process becomes more complex
Solution Approach 1:
The system uses the web's own heat to drive the cooling process. The hot web itself provides the energy for evaporative cooling of the water mist, eliminating the need for external power sources or complex mechanical cooling systems. The web's thermal energy is converted into evaporative cooling action.
Solution Approach 2:
The patent replaces mechanical cooling systems (such as chilled air systems or water spray systems requiring pumps) with a passive evaporative cooling system. The water mist is introduced in a fine spray form and evaporates naturally on contact with the hot web, substituting complex mechanical cooling infrastructure with a simpler evaporative process.
3Quantity of substance
If steam is applied to moisten the fibrous web, then moisture content increases, but the heating effect is limited to the surface area
Solution Approach 1:
The steam injection system applies moisture and heat locally at the point of injection rather than uniformly across the entire web. The steam is introduced through nozzles positioned to target specific areas, creating localized zones of high moisture and heat that then diffuse into the surrounding web material, achieving controlled moisture distribution.
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 ensures volume-saving smoothing with improved surface quality and minimal line impairment during rolling, maintaining moisture and temperature stability for optimal web processing.
Implementation Method 1
the fibrous web is cooled by means of at least one cooling unit before the first and between the first and the further smoothing device... Evaporative cooling has proven to be an efficient cooling method
Implementation Method 2
When exposed to steam, condensation and heating occur on the exposed side of the fibrous web
Data Source
AI summary
The invention relates to a method for treating a fibrous web (1), in particular a paper or carton web in the end section of a machine for production thereof, which comprises a dryer section (2) for drying, a first smoothing device (3) for pre-smoothing, a coating device (9) for applying coating color, an additional smoothing device (4) and a rolling device (5) for winding the finished fibrous web (1), wherein the fibrous web (1) is guided through at least one cooling unit (6, 7, 10) having evaporation cooling between the drying section (2) and the rolling device (5). According to the invention, volume-protective smoothing and optimal rolling is enabled in that the fibrous web (1) is cooled by at least one cooling unit (6, 7, 10) in each case before the first (3) and between the first (3) and the additional smoothing device (4).