Segmented Polymer Seal for Cellulose Pulp Drum
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Solution Overview
Problem
Existing washing arrangements for cellulose pulp, such as drum washers and washing presses, face issues with polymer seals elongating and fracturing due to high tensile stresses, leading to potential damage and loss of sealing effectiveness, especially when the seals are subjected to heat and chemical exposure.
Innovation Solution
Incorporating a reinforcing arming element, like a thin steel band, within the polymer seal to counteract tensile stresses, attached via joints along the seal's longitudinal extension, which provides improved mechanical support and resistance to creep, heat, and chemical exposure, while maintaining flexibility and reducing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an overall end seal extending about the entire circumference of the rotary cylindrical element is used, then the sealing effectiveness is improved, but the seal elongates by creep and fractures due to significant tensile stresses
Solution Approach 1:
The seal is divided into multiple separate arc-shaped seal segments instead of a single continuous circumferential seal. Each segment spans only a portion of the circumference (e.g., 180-270 degrees) and is independently supported by the application means, eliminating the continuous tensile stress that causes creep and fracture in full-circumference seals while maintaining effective sealing at the drum end.
Solution Approach 2:
The problematic circumferential sealing function is extracted from the continuous seal structure. Instead of requiring a complete 360-degree seal, the invention uses discrete seal segments positioned only where sealing is necessary, removing the unnecessary portions that would create continuous tensile stress paths through the polymer material.
2Productivity
If the diameter of the drums or rolls is made relatively great, then the washing capacity is improved, but the seal length increases to 10-15 m, requiring significant force to hold the seal in place
Solution Approach 1:
The seal is divided into multiple separate arc-shaped seal segments instead of a single continuous circumferential seal. Each segment spans only a portion of the circumference (e.g., 180-270 degrees) and is independently supported by the application means, eliminating the continuous tensile stress that causes creep and fracture in full-circumference seals while maintaining effective sealing at the drum end.
3Reliability
If a polymer seal material with high friction coefficient is used, then the sealing contact is improved, but the force required to hold the seal in desired position increases significantly
Solution Approach 1:
The seal is divided into multiple separate arc-shaped seal segments instead of a single continuous circumferential seal. Each segment spans only a portion of the circumference (e.g., 180-270 degrees) and is independently supported by the application means, eliminating the continuous tensile stress that causes creep and fracture in full-circumference seals while maintaining effective sealing at the drum end.
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 reinforced seal design enhances the durability and longevity of the sealing mechanism by distributing tensile stresses effectively, reducing the risk of elongation and fracture, and maintaining effective contact with the rotary elements, thus ensuring consistent operation and extended lifespan.
Implementation Method 1
the tensile stresses arising in the seal at operation can be counteracted
Implementation Method 2
the seal gradually elongates by creep to fracture
Implementation Method 3
The polymer material in the seal should have a low friction coefficient
Implementation Method 4
The arming consists of an easily flexible material with a higher yield point than the polymer material in the seal
Data Source
Figure 1~3
Figure 4
AI summary
A washing arrangement for washing and dewatering cellulose pulp, comprising at least one rotary cylindrical element (5), against which the pulp is dewatered, and where a seal (1 ) is located in an end seal holder (4), so that the seal has a contact surface (6) against the rotary cylindrical element (5) and an application surface (7) placed against application means (8) located in a groove (9) in the end seal holder (4), where the seal has a longitudinal extension, which corresponds to the entire or at least a greater part of the circumference of the cylindrical element and is intended to seal against the end of the cylindrical element, and where the seal is a polymer ledge (2) provided with an arming element (3).