Turbine Casing Screw Fastening Ferritic Austenitic Steel
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Solution Overview
Problem
The existing supercritical CO2 turbine systems face challenges in maintaining structural stability and reliability at the connection between ferritic and austenitic heat-resistant steel components, leading to potential cracking and increased manufacturing costs due to differences in chemical composition, expansion coefficients, and temperature stability, making it difficult to achieve long-term structural integrity and efficient power generation.
Innovation Solution
The use of screws to fasten the exhaust pipe made of austenitic heat-resistant steel to a ferritic heat-resistant steel pipe barrel part in the turbine casing, eliminating the need for welding and reducing manufacturing complexity, thereby enhancing structural stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to connect exhaust pipe (austenitic steel) to pipe barrel part (ferritic steel), then structural connection is achieved, but structural stability and reliability deteriorate due to material incompatibility
Solution Approach 1:
A transition piece made of ferritic heat-resistant steel is introduced as an intermediary component between the austenitic exhaust pipe and the ferritic pipe barrel part. This transition piece has a first connection portion that connects to the exhaust pipe and a second connection portion that connects to the pipe barrel part, thereby avoiding direct welding between incompatible austenitic and ferritic steels and preventing cracking at the weld joint.
2Ease of manufacture
If welding is used to connect different steel types, then connection is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The connection structure is segmented into three distinct parts: the austenitic exhaust pipe, the ferritic transition piece, and the ferritic pipe barrel part. Each component can be manufactured independently using appropriate materials and processes, and then assembled together through simpler connection methods such as flange connections or mechanical fastening, rather than requiring complex multi-material welding procedures.
3Ease of operation
If direct connection between exhaust pipe and pipe barrel part is made, then assembly is simple, but structural instability occurs at high temperatures
Solution Approach 1:
The transition piece acts as a thermal and structural intermediary that is compatible with both the exhaust pipe and pipe barrel part. It provides a stable connection interface that can accommodate thermal expansion and contraction at high temperatures without causing structural instability, while still maintaining a relatively simple assembly process.
Data Source
AI summary
There is provided a turbine casing capable of easily realizing improvement of reliability regarding a connection with an exhaust pipe. A turbine casing according to an embodiment includes an exhaust pipe connecting part formed of ferritic heat resistant steel, to which an exhaust pipe formed of austenitic heat resistant steel is connected. Here, the exhaust pipe connecting part and the exhaust pipe are fastened by using screws.