Cross-machine Direction Actuators for Press Felt Moisture Control
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Solution Overview
Problem
Current papermaking machinery lacks effective cross-machine direction control of press felts, which affects the moisture content and quality of the paper sheet, leading to inefficiencies in water absorption and energy usage.
Innovation Solution
A system and method that measures the moisture content of the paper sheet, adjusts the water absorption efficiency of press felts by spraying water or removing it through vacuum in specific zones, optimizing the moisture profile across the machine direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If actuators add steam in various zones across the sheet to increase temperature and facilitate water removal, then water removal efficiency is improved, but sheet bulk is reduced
Solution Approach 1:
The press felt is divided into multiple independent actuatable zones across the machine direction, allowing each zone to have different water removal characteristics. This enables localized control of water removal efficiency without uniformly affecting the entire sheet, thereby maintaining sheet bulk in zones where it is not needed to be reduced.
Solution Approach 2:
The press felt is segmented into discrete actuatable zones that can be controlled independently. This segmentation allows selective water removal in specific zones while preserving bulk in other zones, resolving the contradiction between overall water removal efficiency and sheet bulk maintenance.
2Manufacturing precision
If water is sprayed on the sheet in zones to affect cross-machine direction moisture content, then moisture uniformity is improved, but energy efficiency deteriorates and paper quality variation increases
Solution Approach 1:
Water is sprayed on the press felt before the sheet contacts it, pre-conditioning the press felt zones with appropriate moisture levels. This preliminary action allows the press felt to transfer the correct amount of moisture to the sheet during pressing, achieving moisture uniformity without requiring subsequent energy-intensive water spraying on the sheet itself.
Solution Approach 2:
The press felt serves as an intermediary medium between the water supply system and the paper sheet. Instead of spraying water directly on the sheet, the system sprays water on the press felt, which then acts as a controlled moisture transfer medium to the sheet, improving energy efficiency and reducing paper quality variation.
3Device complexity
If all actions on the press felt are performed in the machine direction, then press felt processing is simplified, but cross-machine direction sheet quality control is insufficient
Solution Approach 1:
The press felt is divided into multiple actuatable zones in the cross-machine direction, allowing independent control of each zone. This segmentation enables precise cross-machine direction quality control while maintaining relatively simple processing through modular zone control rather than complex continuous adjustment.
Solution Approach 2:
Different zones of the press felt in the cross-machine direction are given different water application characteristics to match the specific quality requirements of different sheet zones. This local quality approach enables precise cross-machine direction control without requiring complex global processing systems.
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
Enhances water absorption efficiency of press felts, reduces energy consumption, and improves moisture uniformity of the paper sheet by dynamically managing water absorption and removal processes.
Implementation Method 1
providing a water-spraying device to spray water on the press felt, selecting one or more zones on the press felt in which to spray water
Implementation Method 2
a vacuum device for removing water from the press felt by suction can be provided
Data Source
AI summary
A method for affecting moisture content of a sheet of paper includes providing a moisture measuring device disposed in a papermaking machine to measure the moisture content of a sheet of paper and create a moisture profile of the sheet of paper, determining the moisture profile of the sheet of paper, and providing a water-spraying device to spray water on a press felt that contacts the sheet of paper during manufacturing. The method further includes selecting one or more zones on the press felt on which to spray water based on the moisture profile of the sheet of paper, and acting on the press felt by spraying water in the one or more selected zones on the press felt to affect the moisture content of the sheet of paper that contacts the press felt after the water has been sprayed.