Variable Guide Roller and Steam Blow Box for Press Section Web Transfer
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Solution Overview
Problem
Existing press sections in machines producing fibrous webs, such as paper or cardboard, face challenges with web adhesion and dewatering performance at high machine speeds and high basis weights, leading to unreliable web travel and suboptimal dewatering.
Innovation Solution
The press section incorporates a variable guide roller and a steam blow box that can be positioned to adjust the guided path length and steam application, ensuring reliable web transfer and enhanced dewatering by using a steam blow box that moves in conjunction with the guide roller, maintaining web stability and preventing condensation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed guided path is used before the second press nip, then the structure is simple, but the adaptability to different web types and machine speeds is limited
Solution Approach 1:
The guide roller is designed to be movable rather than fixed, allowing it to adjust its position along the belt path. This enables the guided path length to be dynamically changed according to different web types and machine speeds, providing adaptability while maintaining a relatively simple overall structure.
Solution Approach 2:
The invention changes the parameter of guided path length by moving the guide roller to different positions. This parameter adjustment allows the system to adapt to various operating conditions (different web types, basis weights, and machine speeds) without requiring a completely different structural design.
2Reliability
If the guided path is made longer to provide more space for steam blow box, then steam application is improved, but web travel reliability decreases due to extended distance
Solution Approach 1:
The guide roller can be positioned dynamically to optimize the balance between guided path length and steam blow box space. By adjusting the guide roller position, the system can achieve reliable web travel while providing sufficient space for effective steam application, depending on the specific operating conditions.
3Reliability
If steam blow box is arranged above the fibrous web, then steam application is effective, but condensation water drips and impairs the web
Solution Approach 1:
Instead of arranging the steam blow box above the web (which causes condensation water to drip down and damage the web), the invention positions the steam blow box below the web. The steam is blown upward through the web, achieving effective steam application for dewatering while preventing condensation water from contacting and damaging the web.
Solution Approach 2:
The steam blow box acts as an intermediary device that delivers steam to the web from below. This intermediary positioning allows steam to penetrate the web effectively for dewatering while the web itself serves as a barrier preventing condensation water from reaching and damaging the web surface.
4Reliability
If the upper press belt bridges a long distance between vacuum assisted guide roller and guided path, then web transfer is reliable, but steam blow box installation space is insufficient
Solution Approach 1:
The guide roller position can be dynamically adjusted to optimize the balance between web transfer reliability and steam blow box installation space. By moving the guide roller, the system can achieve both reliable web transfer and sufficient space for steam blow box installation, depending on the specific operational requirements.
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 configuration improves web travel reliability and dewatering performance, allowing for flexible operation across various web types and machine speeds with increased dry content and reduced risk of web lift-off, while maintaining belt path geometry and extending press nip compaction pressure for efficient water removal.
Implementation Method 1
A suction device in the form of a vacuum assisted guide roller or a suction box of the bottom felt which is arranged at the point of separation serves to hold the fibrous web at the point of separation on the bottom felt.
Implementation Method 2
The dry content of the web and thus the dewatering performance of the press section can be substantially increased by applying steam to the steam blow box.
Implementation Method 3
a press section in a machine for producing a fibrous web, in particular a paper, cardboard or tissue web, having two press nips, positioned one after the other in direction of web travel and respectively formed by two press elements
Data Source
AI summary
A press section which includes first and second press nips and at least one separate continuously revolving press belt which is routed around each press element of each press nip over a plurality of guide rollers. An upper press belt is led away from the fibrous web after the first press nip. Thereafter the fibrous web is transferred from a lower press belt of the first press nip to an upper press belt of the second press nip. The upper press belt of the second press nip wraps around a vacuum assisted guide roller. Thereafter the lower press belt of the second press nip is brought into contact with the fibrous web via a guide roller, after which the fibrous web travels to the second press nip via a guided path jointly with the two opposite upper and lower press belts of the second press nip.