Rotating Lower Turbine Shell for Gas Engine Maintenance
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Solution Overview
Problem
The removal and reinstallation of the lower inner turbine shell in gas turbine engines pose significant challenges due to its location and precision of installation, complicating complete inspections and maintenance, especially when trying to access components like rotor wheels and buckets without fully disassembling the turbine section.
Innovation Solution
A method and system that involves using a counterweight to replace the upper inner shell, combined with a thrust collar locator and roller assemblies to rotate the lower inner shell from a lower position to an upper position, allowing for its removal and reinstallation, while maintaining axial alignment and using a drive system and braking unit for controlled rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lower inner turbine shell is removed for complete inspection, then access to all rotor components is improved, but the complexity of removal and reinstallation increases significantly
Solution Approach 1:
The turbine shell assembly is divided into multiple segments: outer shell, upper inner shell, and lower inner shell. This segmentation allows the lower inner shell to be independently removed and repositioned without requiring complete disassembly of the entire turbine section, thereby improving access to rotor components while reducing operational complexity
Solution Approach 2:
The lower inner shell is repositioned from its original lower position to an upper position above the rotor assembly. This dimensional change in positioning allows inspection personnel to access rotor components from the upper side, avoiding the complexity of removing the entire shell assembly while still achieving complete inspection capability
2Strength
If the lower inner shell remains in place, then structural integrity is maintained, but access to rotor components in the lower half is complicated
Solution Approach 1:
The inner shell is segmented into upper and lower portions that can be independently manipulated. The lower inner shell can be selectively removed and repositioned while the upper shell and outer shell remain in place, maintaining overall structural integrity while providing access to rotor components
Solution Approach 2:
A support structure acts as an intermediary element to hold the lower inner shell in the repositioned upper location. This intermediary support system allows the shell to be moved from the lower position without compromising structural integrity, while enabling access to rotor components that would otherwise be blocked
3Manufacturing precision
If precision installation of the lower shell is ensured, then alignment accuracy is improved, but the difficulty of precise reinstallation increases
Solution Approach 1:
Alignment features and positioning mechanisms are pre-configured on the lower inner shell and corresponding mounting surfaces before the shell is removed. These preliminary positioning elements guide the reinstallation process, ensuring that when the shell is repositioned and reinstalled, precise alignment is automatically achieved without requiring complex realignment procedures
Solution Approach 2:
Complex mechanical alignment procedures are replaced with self-aligning features such as tapered surfaces, keyed connections, or guided rails that automatically ensure proper alignment during reinstallation. This substitution reduces the skill level and equipment needed for precise reinstallation while maintaining high alignment accuracy
Data Source
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AI summary
A method and system adapted for removing one or more shells from an assembly of multiple annular shells (14, 16, 18, 20), for example, turbine shells of a gas turbine engine (10). The method includes removing an upper shell (14, 18) positioned in an upper position relative to a lower shell (16, 20) of the assembly of multiple annular shells, and then positioning and securing a counterweight (22) in the upper position and securing the counterweight (22) to the lower shell as a replacement for the upper shell in the upper position. The counterweight (22) and the lower shell (16, 20) are then rotated in unison until the lower shell is in the upper position and the counterweight (22) is in a lower position previously occupied by the lower shell. Thereafter, the lower shell (16, 20) can be removed from the assembly.