Permeable Belt Press System for Tissue Dewatering
Solution Overview
Problem
Conventional tissue paper manufacturing processes, particularly those using the TAD system, face inefficiencies in dewatering and high operational costs due to limited permeability and high energy consumption, resulting in suboptimal web quality and increased costs.
Innovation Solution
A permeable belt press system with a spiral link fabric is used, allowing for extended nip lengths and airflow through the web, reducing peak pressures and enhancing dewatering efficiency by applying tension and air flow simultaneously, which increases the solids content of the paper web to 35% or more while maintaining high quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional wet pressing method is used, then the paper web is compressed to dewater, but only a small portion of the press roll circumference is utilized, resulting in limited productivity
Solution Approach 1:
The patent transforms the static press nip into a dynamic extended nip press system where a flexible permeable belt replaces the rigid press roll surface. This allows the press nip to be extended along the belt length while maintaining flexibility and permeability, enabling a much longer pressing zone that utilizes a larger portion of the press roll circumference for dewatering operations
Solution Approach 2:
The invention extends the pressing operation from a traditional point-contact or line-contact press nip into a distributed area press nip along the extended belt length. This dimensional extension allows multiple zones of the belt to simultaneously engage in dewatering, significantly increasing the effective pressing utilization and productivity
2Duration of action of moving object
If an impermeable belt is used for extended nip pressing, then the pressing dwell time is increased, but the flow of drying fluid through the paper web is prevented
Solution Approach 1:
The patent employs a flexible permeable belt made of porous or mesh-like material that allows drying fluid (air) to pass through it and the paper web simultaneously. This permeable structure maintains the extended pressing dwell time while enabling continuous air flow for drying, resolving the contradiction between prolonged mechanical pressing and drying fluid penetration
Solution Approach 2:
The flexible permeable belt performs multiple functions simultaneously: it provides the mechanical pressing force for dewatering, allows air flow through its permeable structure for drying, and maintains the extended nip geometry. This multi-functionality enables both extended pressing dwell time and continuous drying fluid flow without compromise
3Stress or pressure
If a solid press roll is used, then high pressure is applied for dewatering, but the peak pressure causes excessive compression and reduces web quality
Solution Approach 1:
The patent segments the pressing pressure application along the extended belt length, distributing the total dewatering load across multiple zones rather than concentrating it at a single point. This segmentation allows lower peak pressures to achieve the same overall dewatering effect, preventing excessive compression and preserving web quality while maintaining effective pressure for water removal
4Manufacturing precision
If the TAD system is used for drying, then web quality is improved with higher bulk, but the operational costs and energy consumption increase significantly
Solution Approach 1:
The patent merges the dewatering and drying operations into a single integrated extended nip press system. By combining mechanical pressing with simultaneous air flow through the permeable belt, the system achieves both water removal and drying in one step, eliminating the need for separate high-energy TAD drying operations while maintaining web quality and bulk characteristics
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 system achieves higher web solids content and improved quality with reduced operational costs by extending the press nip and incorporating airflow, enabling more efficient dewatering and reducing the need for extensive vacuum systems.
Implementation Method 1
a fibrous web sheet is compressed at a press nip to the point where hydraulic pressure drives water out of the fibrous web
Implementation Method 2
The belt and the structured fabric are permeable. The belt can be a spiral link fabric and can be a permeable ENP belt in order to promote vacuum and pressing dewatering simultaneously
Implementation Method 3
The belt can be a spiral link fabric and can be a permeable ENP belt in order to promote vacuum and pressing dewatering simultaneously
Data Source
AI summary
A forming fabric for an ATMOS system or a TAD machine. The forming fabric includes a permeability value of between approximately 100 cfm and approximately 1200 cfm, a paper surface contact area of between approximately 0.5% and approximately 90% when not under pressure and tension, and an open area of between approximately 1.0% and approximately 90%. A belt press for a paper machine can utilize the forming fabric. 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.