Gas Turbine Casing Division for Reduced Flange Force
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Solution Overview
Problem
Conventional gas turbines face challenges in reducing the force acting on divided casings due to high-pressure fluids, leading to larger flanges and potential size limitations during transportation and maintenance.
Innovation Solution
The divided portion is relocated from the combustor casing to a downstream portion of the turbine unit chamber, where the pressure is lower, allowing for a downsized flange and reduced force on the casing, and the load coupling cover is designed to be detachable without requiring access to the combustor chamber for maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the divided portion is formed in the combustor casing, then the casing can be divided for assembly and transportation, but the force acting on the divided portion becomes large due to high-pressure fluid
Solution Approach 1:
The casing is divided into multiple portions with flanges for assembly, but the division is strategically placed in the turbine unit chamber rather than the combustor casing to reduce force on the divided portion
Solution Approach 2:
The divided portion is specifically located in the turbine unit chamber where the fluid pressure is lower, creating a local region with different pressure characteristics compared to the combustor casing
2Strength
If the flange at the divided portion is made large to withstand high force, then the structural strength is improved, but the overall size of the casing increases beyond transportation limits
Solution Approach 1:
The divided portion is positioned in the turbine unit chamber where lower fluid pressure allows for a smaller flange size while maintaining sufficient strength, thereby keeping the overall casing size within transportation limits
3Ease of repair
If maintenance requires access to the combustor chamber, then thorough maintenance can be performed, but the maintenance time and manpower increase
Solution Approach 1:
The load coupling cover is designed to be detachable from the outside of the combustor chamber, allowing the combustor to be extracted and maintained without requiring workers to enter the combustor chamber, thereby reducing maintenance time and manpower
Data Source
Figure 1
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AI summary
A gas turbine 1 includes a combustor chamber 36 that houses a combustor unit 30 configured to include a combustor 39 that burns fuel to generate combustion gas for rotating a rotor 50, a turbine unit chamber that houses a turbine-unit rotor blade and a disk that rotate upon reception of the combustion gas, a combustor casing 31 that forms the combustor chamber 36, and a casing 60 that is configured to include the combustor casing 31 in which a divided portion on a surface orthogonal to a rotation axis RL of the rotor 50 is not formed in the combustor casing 31, but is formed in a portion on a downstream side of flow of the combustion gas lower than the combustor casing 31.