Catalyst Support Joint Positioning for Thermal Stress Reduction
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Solution Overview
Problem
Catalyst supports with large holes in catalytic devices experience nonuniform thermal stress and low stiffness, leading to deformation and potential damage at brazed areas due to thermal strain, especially near the center where catalyst activation increases temperature.
Innovation Solution
A catalytic device design featuring a catalyst support formed by stacked and rolled metal leaf-shaped flat and corrugated plates with holes, where the joint areas between the plates and the outer cylinder are strategically located away from the central high-temperature region to reduce the impact of thermal stress, increasing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large holes are provided in the flat plate and corrugated plate to form the catalyst support, then exhaust gas flow and catalyst contact are improved, but thermal stress becomes nonuniform and thermal strain is produced leading to deformation
Solution Approach 1:
The joint areas between flat plates and corrugated plates are strategically positioned in upstream regions with lower thermal stress, creating local quality differences in the structure. This allows the catalyst support to maintain structural integrity in high-stress areas while preserving flow efficiency through appropriately sized holes in less stressed regions.
Solution Approach 2:
The catalyst support is segmented into multiple flat plates and corrugated plates joined together, with joint areas distributed in specific regions. This segmentation allows different parts of the structure to handle thermal stress differently, with upstream joint areas experiencing less stress than downstream areas, thereby preventing overall deformation.
2Productivity
If the catalyst support has holes, then exhaust gas can pass through and contact the catalyst, but the stiffness of the plate is reduced making it more prone to deformation
Solution Approach 1:
Corrugated plates with curved wave patterns are used instead of completely flat plates. The curvature provides structural rigidity and resistance to deformation while still allowing holes to be formed for exhaust gas flow. The corrugated structure maintains stiffness better than flat plates with the same hole configuration.
Solution Approach 2:
The catalyst support uses a composite structure combining flat plates and corrugated plates joined together. This composite construction provides enhanced stiffness and structural integrity compared to single-plate designs, allowing adequate hole size for catalyst contact while maintaining resistance to thermal deformation.
3Strength
If brazing is performed near the center where catalyst temperature is high, then the catalyst support is fixed securely, but the brazed part and surrounding area may be damaged due to thermal strain
Solution Approach 1:
The joint areas are extracted from the high-temperature central region and repositioned in upstream areas where thermal stress is lower. This separation removes the vulnerable brazed joints from the most severe thermal environment, preventing damage while maintaining secure fixation of the catalyst support structure.
Solution Approach 2:
The flat plates and corrugated plates are joined together in upstream areas before the exhaust gas reaches the high-temperature catalyst activation zone. This preliminary joining action occurs in a lower thermal stress environment, ensuring joint integrity before the structure is subjected to high temperatures and thermal strain.
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 design enhances the durability of the catalyst support by distributing thermal stress more evenly and preventing damage from brazing, while maintaining efficient exhaust gas cleanup through turbulent flow generation and increased contact with the catalyst.
Implementation Method 1
When heat is applied to a catalyst support by exhaust gas, thermal stress is generated in the catalyst support
Implementation Method 2
the thermal stress becomes nonuniform and thermal strain is produced
Implementation Method 3
because a catalyst becomes activated and the temperature of the catalyst increases near the center in the flow direction of the exhaust gas
Implementation Method 4
the temperature of the catalyst increases near the center in the flow direction of the exhaust gas
Implementation Method 5
If the members near the center are brazed and fixed, a brazed part and an area around the brazed part may be damaged
Data Source
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AI summary
A catalytic device that can increase the durability of a catalyst support with holes is provided. A flat plate (52) and a corrugated plate (54) have a plurality of holes (64), a joint area between the flat plate (52) and the corrugated plate (54) is provided in a first upstream area (70) including one end (42a) of a catalyst support (42), and a joint area between the catalyst support (42) and an outer cylinder (44) is provided in a second upstream area (72) that includes the first upstream area (70) and is wider than the first upstream area (70) in the direction of an axis.