Crescent Former Dewatering for Tissue Bulk
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Solution Overview
Problem
Conventional tissue paper production methods using Crescent formers face challenges in achieving high-quality paper due to energy costs and the negative impact of pressing on the paper web's bulk, as they require expensive TAD machines and result in substantial energy losses and quality degradation.
Innovation Solution
A method where the fibrous pulp web is guided over a suction roll with the forming wire and felt immediately after the forming roll, applying gentle dewatering without pressing belts, using hot fluid for enhanced dewatering, and transferring to a Yankee with a shoe press roll, allowing for increased dryness and fiber resistance to mechanical pressing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pressing is applied to increase dryness content before Yankee transfer, then the necessary dryness content is achieved, but the paper web loses bulk and quality deteriorates
Solution Approach 1:
The patent replaces mechanical pressing with a combination of centrifugal dewatering in the Crescent former and thermal drying on the Yankee. The forming section uses centrifugal force to achieve higher dryness content, eliminating or reducing the need for mechanical presses that would compress and reduce bulk.
Solution Approach 2:
The patent performs dewatering in the forming section before the web reaches the Yankee, achieving a higher initial dryness content. This preliminary dewatering action reduces the moisture burden on subsequent drying stages and eliminates the need for aggressive pressing that would harm bulk.
2Quantity of substance
If conventional pressing and drying processes are used, then the necessary dryness is achieved, but substantial energy costs are incurred
Solution Approach 1:
The patent replaces energy-intensive thermal drying with mechanical centrifugal dewatering in the Crescent former. By achieving higher dryness content through centrifugal force before Yankee transfer, the required drying time and energy consumption are substantially reduced.
Solution Approach 2:
The Crescent former utilizes the motion of the machine itself to generate centrifugal force for dewatering, rather than requiring separate high-energy drying systems. The forming section performs dewatering as part of its normal operation, reducing overall energy requirements.
3Manufacturing precision
If TAD machines are used to produce high-quality paper, then product quality is excellent, but the purchase cost and energy costs are much higher
Solution Approach 1:
The patent merges the dewatering function into the Crescent former forming section, combining what would traditionally be separate operations. This integration achieves high-quality results using conventional tissue machine infrastructure, avoiding the need for expensive TAD machine installations.
Solution Approach 2:
The patent changes the operating parameters of the Crescent former to achieve higher dryness content and improved web quality. By optimizing centrifugal force, forming section configuration, and Yankee transfer timing, high-quality paper can be produced on conventional machines rather than requiring specialized TAD equipment.
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 approach increases the dryness of the fibrous pulp web to over 30% before reaching the Yankee, maintaining bulk and reducing energy costs by eliminating the need for additional drying steps, while improving dewatering efficiency and fiber resistance.
Implementation Method 1
the fibrous pulp web is guided over a suction roll together with the forming wire and the felt immediately after the forming roll and is further dewatered there
Implementation Method 2
the fibrous pulp suspension is dewatered by centrifugal force in the area of a forming roll
Implementation Method 3
a hot fluid flows through the fibrous pulp web, for example hot air at a temperature of more than 150° C., in particular more than 200° C., preferably more than 250° C.
Implementation Method 4
finally pressed mechanically because no further dewatering by vacuum is possible on the wet felt. The dryness increased to approximately 40% in this process. It is followed by thermal drying on the Yankee.
Data Source
AI summary
A method for producing a fibrous material web, particularly for producing a tissue or hygienic paper web, in which a fibrous suspension is dewatered in a crescent former to obtain a fibrous material web, and dried on a Yankee. After the crescent former, the fibrous material web is guided along with the forming screen and felt over a suction roller downstream of the forming roller. A device for carrying out the method for producing a fibrous material web.