Segmented Gas Duct Linings for Thermal Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas ducts in gas turbines are prone to cracking due to stress accumulation and thermal stresses, and they have limited maintenance and repair accessibility.
Innovation Solution
The gas duct is segmented into independent metal sheets with a mounting structure that allows for stress-free thermal expansion, using radial support struts with linings and fastening screws or stud bolts for easy assembly and disassembly, ensuring that each segment can expand freely and reducing thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the gas duct is constructed by welding preformed parts together to form closed halves, then a closed flow duct is achieved, but stress accumulation and susceptibility to cracks occur due to large inherent welding stresses and high thermal stresses
Solution Approach 1:
The gas duct is divided into multiple segments that are detachably fastened together using support struts with lining segments. This segmentation eliminates the need for continuous welding, allowing each segment to be independently installed and removed, thereby reducing stress accumulation and crack susceptibility while maintaining closed flow duct integrity.
Solution Approach 2:
The support struts are designed with a degree of freedom that allows them to pivot or adjust position, enabling dynamic adaptation to thermal expansion and contraction of the lining segments. This dynamic capability reduces thermal stress accumulation compared to rigid welded connections.
2Stability of the object's composition
If the gas duct is constructed by welding preformed parts together, then a closed flow duct is achieved, but severe vibrations in combination with low natural frequencies occur
Solution Approach 1:
The gas duct is divided into multiple segments that are detachably fastened together using support struts with lining segments. This segmentation eliminates the need for continuous welding, allowing each segment to be independently installed and removed, thereby reducing stress accumulation and crack susceptibility while maintaining closed flow duct integrity.
Solution Approach 2:
The support struts are designed with a degree of freedom that allows them to pivot or adjust position, enabling dynamic adaptation to thermal expansion and contraction of the lining segments. This dynamic capability reduces thermal stress accumulation compared to rigid welded connections.
3Stability of the object's composition
If the gas duct is constructed by welding preformed parts together, then a closed flow duct is achieved, but poor scope for maintenance and repair results
Solution Approach 1:
The gas duct is divided into multiple segments that are detachably fastened together using support struts with lining segments. This segmentation eliminates the need for continuous welding, allowing each segment to be independently installed and removed, thereby reducing stress accumulation and crack susceptibility while maintaining closed flow duct integrity.
Solution Approach 2:
The lining segments can be individually removed and replaced without disassembling the entire gas duct structure. This allows for easy maintenance and repair of specific worn or damaged segments while the remaining segments continue to function, significantly improving maintenance accessibility compared to welded constructions.
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 design enhances maintenance accessibility and minimizes thermal stresses, reducing the risk of cracking and improving the overall durability of the gas duct.
Implementation Method 1
the support struts, the outer casing and the inner casing are equipped in each case with a heat-resistant lining for protection against the hot exhaust gases
Implementation Method 2
an individual entirely stress-free, or almost stress-free, thermal expansion of the individual segments in an expansion plane is possible
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention refers to a gas duct (17) for a gas turbine, which gas duct (17) is formed by a concentric inner casing (19) and an outer casing (18) which concentrically encompasses the inner casing (19) at a distance, and through which the exhaust gases from the gas turbine discharge to the outside, wherein the inner casing (19) and the outer casing (18) are interconnected by means of a multiplicity of radial support struts (20), and wherein the support struts (20), the outer casing (18) and the inner casing (19) are equipped in each case with a heat-resistant lining (19a or 20a) for protection against the hot exhaust gases. Easy accessibility and an extensive reduction of thermal stresses is achieved by the linings of the support struts (20), of the outer casing (18) and of the inner casing (19) being divided in each case into a plurality of separate segments (19a, 20a) which are fastened on a support structure in such a way that an individual thermal expansion of the individual segments is possible.