Pocket Ventilator for Offset Drying Cylinders
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Solution Overview
Problem
Traditional ventilation systems struggle to effectively ventilate offset pocket spaces in papermaking machines due to reduced felt support length and natural air currents, leading to decreased air flow and drying efficiency.
Innovation Solution
A device with an elongated body and multiple plenum chambers is used to create a negative pressure zone between the first drying cylinder and the first cleft, and a positive pressure zone between the third cleft and the second cleft, utilizing blowing holes and air outlets to direct hot dry air over the felt, ensuring efficient air penetration and balancing air flow within the pocket space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the felt roll is positioned intermediate the axis of rotation of adjacent drying cylinders, then the paper web is repetitively unsupported, but moving the felt roll axis backwards towards the wet end increases the length of unsupported paper web
Solution Approach 1:
The pocket ventilator device acts as an intermediary element positioned within the offset pocket space to manage air flow and pressure zones, indirectly supporting the paper web by creating controlled atmospheric conditions that prevent rupture while allowing the felt roll to maintain its offset position
2Quantity of substance
If traditional ventilation systems are used in offset pocket spaces, then air flow is reduced due to natural air currents, but increasing ventilation intensity would disrupt the natural air current balance
Solution Approach 1:
The ventilation system is segmented into multiple functional zones within the pocket ventilator device: a first air outlet for creating negative pressure zones, a second air outlet for creating positive pressure zones, and a third air outlet for supplemental ventilation. This segmentation allows independent control of different air flow patterns without requiring a completely complex system
Solution Approach 2:
Different regions of the pocket space are given different air flow characteristics: the first air outlet creates a negative pressure zone in one region, the second air outlet creates a positive pressure zone in another region, and the third air outlet provides supplemental flow. This local differentiation allows the system to work with natural air currents rather than against them uniformly throughout the entire pocket space
3Productivity
If heated air is injected at numerous locations to promote moisture removal, then drying efficiency increases, but the complexity of the ventilation network increases
Solution Approach 1:
Multiple air outlets are merged into a single integrated pocket ventilator device that is positioned within the offset pocket space. This consolidation allows the device to provide heated air at multiple locations (first, second, and third air outlets) while maintaining a single, manageable unit rather than requiring separate ventilation systems at each location
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 enhances air flow and humidity reduction in offset pocket spaces, maximizing water evaporation and maintaining paper web stability by promoting continuous contact with the felt, thereby increasing the overall drying capacity and reducing sheet instability.
Implementation Method 1
a first air outlet (52) from which a first air stream is directed on the surface of the felt between the first drying cylinder (20a) and the first cleft (34); the first air stream being in a direction which is substantially opposite a running direction of the felt
Implementation Method 2
the first air stream being in a direction which is substantially opposite a running direction of the felt; wherein the first air stream establishes a negative pressure zone between the first drying cylinder and the first cleft
Implementation Method 3
a series of blowing holes (71) provided in the second wall and supplying hot dry air over the surface of the felt between the third cleft (36) and the second cleft (32); wherein the series of blowing holes supplying hot dry air creates a positive pressure zone between the third cleft and the second cleft
Implementation Method 4
promoting water evaporation from the humid components, particularly the paper web (14)
Implementation Method 5
supplying hot dry air over the surface of the felt
Implementation Method 6
natural air currents generated in the pocket space by the moving paper web and felt, as well as the rotation of the drying cylinders and the felt rolls
Data Source
AI summary
A system and a method for ventilating an offset pocket space located in a drying section of a papermaking machine, the offset pocket space being situated between three axially parallel drying cylinders over which a paper web consecutively runs, a first and a third of the drying cylinders being vertically spaced from a second of the drying cylinders, the method comprising creating a positive pressure zone between the body and the felt between the third cleft and the second cleft.