Permeable Belt Press for Extended Nip Dewatering
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Solution Overview
Problem
Conventional papermaking processes, such as through air drying (TAD), are inefficient and costly due to high operational expenses and poor moisture profiles, while existing dewatering methods like extended nip presses face limitations in air flow and pressure distribution, leading to suboptimal paper quality and increased energy consumption.
Innovation Solution
A permeable belt press system that uses a spiral link fabric with high tension and a structured fabric arrangement, allowing for extended nips and simultaneous air flow through the web, which enhances dewatering efficiency and maintains paper quality by distributing pressure effectively and promoting airflow for moisture removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a solid impermeable belt is used in extended nip press, then pressing dwell time is increased, but air flow through the paper web is prevented
Solution Approach 1:
The patent applies a porous belt material that allows air to pass through while maintaining the extended nip press function. The belt contains a network of pores or openings that enable air flow through the paper web during pressing, eliminating the harmful effect of air restriction while preserving the increased pressing dwell time benefit.
2Device complexity
If conventional wet pressing is used, then equipment simplicity is maintained, but dewatering efficiency is low
Solution Approach 1:
The patent segments the pressing process into multiple zones along the extended nip, with different pressure levels and air flow characteristics. This segmentation allows simultaneous mechanical pressing and air drying functions to occur in different sections, significantly improving dewatering efficiency while maintaining relatively simple equipment architecture.
Solution Approach 2:
The extended nip press system performs multiple functions simultaneously: mechanical pressing, air flow through the web, and combined drying. This multi-functionality increases dewatering efficiency without requiring separate dedicated equipment for each function, thus maintaining equipment simplicity.
3Manufacturing precision
If TAD system is used to improve web quality, then bulk and water holding capacity are enhanced, but operational costs and equipment expense increase significantly
Solution Approach 1:
The patent merges the dewatering and drying functions into a single extended nip press system that operates at the paper machine. By combining mechanical pressing with air flow through the porous belt, the system achieves TAD-like web quality improvement without requiring a separate, expensive TAD equipment line, thus reducing operational costs.
Solution Approach 2:
The porous belt acts as an intermediary that enables air to pass through the paper web during pressing, facilitating moisture removal and improving web quality. This intermediary mechanism achieves quality enhancement similar to TAD but through a more cost-effective integrated system rather than requiring extensive vacuum and heating infrastructure.
4Stress or pressure
If extended nip press with impermeable belt is used, then pressing pressure is distributed over longer area, but dewatering is limited to mechanical pressing only
Solution Approach 1:
The porous belt material enables air to flow through the paper web during the extended pressing operation. This adds a pneumatic dewatering mechanism to the existing mechanical pressing, overcoming the limitation of mechanical-only dewatering while maintaining the beneficial pressure distribution over the extended nip area.
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 permeable belt press system achieves higher dewatering efficiency, reducing energy costs and improving paper quality by allowing longer nips with lower peak pressures, reaching higher solids levels while maintaining TAD-like quality, and eliminating the need for extensive vacuum systems.
Implementation Method 1
A differential pressure field is provided between the first and the second surface, acting on the package of at least one upper and at least one lower fabric, and the paper web therebetween
Implementation Method 2
a permeable belt having a tension of at least approximately 30 KN/m applied thereto
Implementation Method 3
a fibrous web sheet is compressed at a press nip to the point where hydraulic pressure drives water out of the fibrous web
Data Source
AI summary
A permeable belt, a belt press including a roll having an exterior surface and the permeable belt, and a method of drying or pressing a web with the permeable belt. The permeable belt has a paper web facing side and is guided over a support surface. The permeable belt can have a tension of between approximately 20 kN/m and approximately 100 KN/m, a permeability value of between approximately 100 cfm and approximately 1200 cfm, a surface contact area of the paper web side that being between approximately 0.5% and approximately 90% when not under tension, and an open area of between approximately 1.0% and approximately 85%. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.