Structured Fabric Press Section for Tissue Bulk and Softness

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Solution Overview

Problem

Current papermaking technologies face challenges in achieving high-quality tissue paper with low production costs, particularly in terms of capital costs, energy consumption, and productivity, due to limitations in web dewatering and transfer processes in hybrid technologies like ATMOS and TAD processes.

Innovation Solution

A novel papermaking machine design incorporating a structuring fabric with a press section that combines the efficiency of Valmet's NTT process with the quality enhancements of TAD technology, featuring a gap former, dewatering fabric, structuring belt, and steam heated cylinder to improve bulk and softness while reducing energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional dry crepe or TAD processes are used, then tissue quality (softness, strength, absorbency) can be achieved, but capital cost and energy consumption increase

Engineering Contradiction:

Improvetissue qualityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent changes the physical parameters of the press section by introducing a structured fabric with specific geometric patterns (ridges and valleys) that modify the compression characteristics. This allows optimized dewatering under reduced energy input compared to conventional TAD processes, achieving tissue quality improvements without proportional energy increases

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The structured fabric incorporates porous regions that facilitate enhanced water drainage from the paper web during pressing. The porous structure allows water to be removed more efficiently at lower compression forces, reducing energy consumption while maintaining or improving tissue quality attributes

Inventive Principle:

Principle #31Porous materials

2Reliability

If TAD technology is used to enhance quality, then softness and bulk improve, but production rate decreases

Engineering Contradiction:

Improvetissue qualityVSAvoidproduction rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The press section is segmented into multiple zones with different structured fabrics, each optimized for specific functions (dewatering, shaping, drying). This segmentation allows parallel processing of different web sections, improving production rate while maintaining quality enhancements associated with TAD technology

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic control of press section parameters including variable compression forces and adjustable fabric configurations. This dynamic adaptation allows optimization of both quality attributes and production speed by adjusting process parameters in real-time based on web characteristics

Inventive Principle:

Principle #15Dynamics

3Use of energy by stationary object

If hybrid technologies like ATMOS are implemented, then energy efficiency improves, but web dewatering and transfer efficiency are limited

Engineering Contradiction:

Improveenergy efficiencyVSAvoiddewatering efficiency

Core Design Contradiction:

Use of energy by stationary objectVSProductivity

Solution Approach 1:

The structured fabric acts as an intermediary between the press roll and the paper web, providing a geometrically patterned surface that enhances capillary action and wick effect. This intermediary structure improves dewatering efficiency by facilitating water removal through the fabric's porous and grooved structure, overcoming limitations of direct contact pressing in hybrid technologies

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If press section intensity is increased to improve dewatering, then water removal improves, but capital cost and energy consumption increase

Engineering Contradiction:

Improvedewatering efficiencyVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by stationary object

Solution Approach 1:

The patent incorporates vacuum assistance in the press section to enhance dewatering. By applying negative pressure through the structured fabric, water is drawn out of the web more effectively without requiring proportionally higher mechanical compression forces, thereby improving dewatering efficiency while controlling energy consumption

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 enables the production of high-quality tissue paper with reduced capital costs and energy consumption, achieving higher production rates and improved web dewatering and transfer efficiency, thereby overcoming the limitations of existing hybrid technologies.

Implementation Method 1

a drying section for drying the partially dewatered paper web to form a dried web, the drying section comprising: (i) a second press element with the inside surface of the structuring fabric in contact with the second press element; (ii) a steam heated cylinder; and (iii) a second nip, formed between the structuring fabric in contact with the second press element and the steam heated cylinder, in which the partially dewatered paper web is pressed and transferred to the steam heated cylinder

Methodology Applied

Scientific EffectEvaporation: Evaporation