Segmented Flexible Seal for Rotary Preheater Wear Reduction
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Solution Overview
Problem
The existing flexible seals in rotary regenerative preheaters experience wear and fatigue due to sliding engagement with sector plates during start-up, leading to bypass leakage and premature failure, exacerbated by stress concentrations and oscillatory vibrations.
Innovation Solution
A seal assembly with a leaf assembly and supplemental leaf assembly, featuring a spacer and additional leaves secured by rivets or spot welds, which slidingly engage each other to accommodate movement and reduce vibrations, and wear-resistant materials are applied to extend the seal's life and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single flexible seal leaf is used, then the seal structure is simple, but the seal experiences wear and fatigue due to sliding engagement with sector plates during start-up
Solution Approach 1:
The seal is divided into multiple flexible seal leaves (first flexible seal leaf, second flexible seal leaf, third flexible seal leaf) instead of using a single seal leaf. Each leaf is secured to the diaphragm and engages with the sector plate surface independently, distributing the wear and stress across multiple components to improve durability while maintaining structural simplicity
Solution Approach 2:
The flexible seal leaves are designed to dynamically engage and disengage with the sector plate surface during operation. During start-up when the sector plate surface moves, the flexible leaves can slide and flex to accommodate the movement, reducing wear and fatigue compared to a rigid single-leaf design
2Reliability
If the seal engages the sector plate surface during start-up, then sealing is achieved, but sliding engagement causes wear and oscillatory vibration
Solution Approach 1:
The sealing function is distributed across multiple flexible seal leaves that can independently contact and slide along the sector plate surface. This segmentation reduces the wear concentration on any single leaf and dampens oscillatory vibrations through the distributed contact points
Solution Approach 2:
The seal uses thin flexible metal leaves that can conform to the sector plate surface while accommodating thermal expansion and movement during start-up. The flexibility of these thin leaves reduces impact and vibration during sliding engagement while maintaining effective sealing contact
3Ease of manufacture
If the seal is mounted on the diaphragm edge, then installation is simplified, but stress concentrations cause premature failure
Solution Approach 1:
The seal is mounted on the diaphragm edge but divided into multiple leaves secured by bolts, distributing the mounting stress across multiple attachment points. This segmentation reduces stress concentrations at any single bolt location while maintaining the simplified edge-mounting installation approach
Solution Approach 2:
The seal assembly combines multiple flexible metal leaves with bolt fasteners and spacing elements to create a composite structure. This composite design distributes mechanical stresses across different components and materials, preventing premature failure at the mounting location while keeping installation straightforward
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 new seal assembly significantly reduces vibrations and wear, extending the seal's life and performance by minimizing leakage and stress concentrations, with a 50% reduction in hot end radial seal gap at full load compared to prior art seals.
Implementation Method 1
A flexible seal assembly includes a first flexible seal leaf, a second flexible seal leaf, and a third flexible seal leaf. The third flexible seal leaf has a wear-resistant material on an outer surface that slidingly engages the sector plate surface during start-up conditions.
Data Source
AI summary
A seal assembly includes a leaf assembly and a supplemental leaf assembly. The leaf assembly includes a first leaf having a first base section. The first base section defines a first fastening area for securing the first leaf to a diaphragm of the preheater. The first leaf has a first elongate section extending away from the first base section and terminating at a first distal end thereof. The leaf assembly further includes a second leaf that engages a portion of the first leaf. The second leaf has a second base section. The second base section defines a second fastening area for securing the second leaf to the diaphragm. The second leaf has a second elongate section extending away from the second base section and terminating at a second distal end thereof. The supplemental leaf assembly is secured to the first leaf and slidingly engaging the second leaf.