Turbine Casing Manufacturing Using Segmented Inner Components
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Solution Overview
Problem
The manufacturing of turbine casings for supercritical CO2 turbines faces challenges in reducing thermal stress and improving reliability due to material limitations and manufacturing defects, particularly with austenitic heat-resistant steel, which can lead to leakage and fatigue issues.
Innovation Solution
A manufacturing method using ferritic heat-resistant steel for the outer casing and austenitic heat-resistant steel for the inner casing, where the inner casing is formed by forging or rolling multiple members assembled via welding, reducing thickness and thermal stress, and incorporating heat-insulating coatings or boards to manage thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If austenitic heat-resistant steel is used for the inner casing, then heat resistance is improved, but manufacturing defects and reliability deteriorate
Solution Approach 1:
The inner casing is divided into multiple members (first inner casing member, second inner casing member, etc.) that are assembled together. This segmentation allows each member to be manufactured with controlled thickness and fewer defects, while maintaining the overall heat resistance function of the inner casing structure.
Solution Approach 2:
Different regions of the inner casing have different thicknesses optimized for their specific functions. The first inner casing member has a first thickness and the second inner casing member has a second thickness, allowing local optimization of heat resistance and manufacturing quality in different areas.
2Strength
If the inner casing thickness is increased, then strength is improved, but thermal stress increases
Solution Approach 1:
The inner casing is segmented into multiple members with optimized thicknesses. This segmentation reduces the overall thickness required while maintaining strength through the assembled structure, thereby reducing thermal stress in the exhaust hood region.
Solution Approach 2:
The inner casing uses a composite structure of multiple members assembled together, combining the strengths of different sections while optimizing the overall thermal and mechanical performance to reduce thermal stress.
3Ease of manufacture
If the inner casing is made as a single piece, then manufacturing is simplified, but manufacturing defects increase
Solution Approach 1:
The inner casing is manufactured as multiple separate members that are subsequently assembled. This approach allows each member to be manufactured with smaller size and reduced complexity, minimizing manufacturing defects while maintaining ease of assembly through standardized joining processes.
Data Source
AI summary
There is provided a manufacturing method of a turbine casing capable of easily realizing improvement of reliability. A manufacturing method of a turbine casing according to an embodiment is a manufacturing method of a turbine casing which includes an outer casing formed of ferritic heat resistant steel and an inner casing disposed inside the outer casing and formed of austenitic heat resistant steel, and in which an exhaust hood to which a working medium after performing work in turbine stages is exhausted, is covered by the inner casing. Here, the inner casing is manufactured by using members produced by at least either forging or rolling.