Gas Turbine Lance Injector Thermal Expansion Management
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Solution Overview
Problem
Lance injectors for gas turbines face issues due to thermal expansion of components, leading to mechanical stress, fitting loss, and potential obstruction of fuel passages, which affects machine efficiency and pollutant emissions.
Innovation Solution
A lance injector design featuring a guiding bushing and elastic contrast device that allows axial sliding of the inner tubular body, coupled with sealing rings to prevent leakage and misalignment, reducing thermal stress and fitting loss by limiting contact points and maintaining a fluid-tight seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid connections are used between tubular bodies, then structural strength is improved, but thermal stress and fitting loss worsen due to differential thermal expansion
Solution Approach 1:
The patent applies the dynamics principle by transforming the rigid static connection between tubular bodies into a dynamic system that allows relative movement. The guiding bushing enables the inner tubular body to slide axially relative to the outer tubular body, accommodating differential thermal expansion while maintaining structural integrity. This dynamic adaptation prevents fitting loss caused by thermal stress.
Solution Approach 2:
The guiding bushing acts as an intermediary element between the inner and outer tubular bodies. It mediates the interaction by providing a controlled interface that allows relative movement while maintaining alignment and preventing uncontrolled separation or misalignment that would lead to fitting loss.
2Reliability
If sliding mechanism is introduced to accommodate thermal expansion, then fitting loss is reduced, but sealing difficulty worsens due to relative movement between components
Solution Approach 1:
The patent employs flexible sealing rings made of elastomeric material that can deform and adapt to the relative movement between tubular bodies. These flexible sealing elements maintain the fluid-tight seal while accommodating the axial sliding motion required to prevent fitting loss from thermal expansion.
Solution Approach 2:
The sealing rings serve as intermediary elements between the guiding bushing and tubular bodies, facilitating the sliding motion while preventing fluid leakage. They mediate the interaction by providing a compliant interface that maintains sealing despite relative movement.
3Reliability
If multiple sealing points are used to prevent leakage, then sealing reliability is improved, but device complexity worsens
Solution Approach 1:
The patent uses flexible sealing rings that can maintain reliable sealing across the sliding interface with a single continuous sealing element rather than multiple discrete sealing points. The flexibility of the elastomeric material allows it to conform to the interface and maintain sealing reliability while simplifying the overall sealing system design.
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
The design effectively mitigates thermal expansion-induced stress, preventing fitting loss and maintaining efficient fuel injection, thus enhancing machine efficiency and reducing the risk of combustion irregularities and emissions.
Implementation Method 1
a guiding bushing and elastic contrast device that allows axial sliding of the inner tubular body
Implementation Method 2
sealing rings to prevent leakage and misalignment, reducing thermal stress and fitting loss by limiting contact points and maintaining a fluid-tight seal
Implementation Method 3
a plurality of coaxial tubular bodies, at one end of which a terminal equipped with a nozzle is fitted. The tubular bodies define between them at least one delivery line between an inlet and the nozzle
Data Source
Figure 1
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Figure 4
AI summary
A lance injector for injecting fuel into a combustion chamber (2) of a gas turbine comprises: a coaxial first tubular body (15) and second tubular body (16); a nozzle (20) connected to respective first ends (15a, 16a) of the first tubular body (15) and of the second tubular body (16); a guiding bushing (30) fitted on the first tubular body (15) so as to allow the relative axial sliding of the first tubular body (15) with respect to the second tubular body (16) due to expansion and contraction; and sealing members (27) between the first tubular body (15) and the guiding bushing (30). The sealing members are defined by at least two sealing rings (38) and the first tubular body (15) and the guiding bushing (30) are separated by an annular gap, except at the sealing rings (38).