Gas Turbine Fuel Nozzle Combustion Oscillation Containment
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Solution Overview
Problem
Premixed combustion in gas turbine combustors is prone to combustion oscillations, leading to high-cycle fatigue and potential damage to combustor components due to oscillation stress, with existing technologies failing to address the risk of scattering from broken fuel nozzle parts.
Innovation Solution
A fuel nozzle design for gas turbine combustors featuring a premixing fuel nozzle with a varying outside diameter, including a root portion, step portion, and distal end portion, where the root portion has a greater outside diameter than the diffusion combustion burner support, reducing stress concentration and preventing scattering of broken pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If premixed combustion is adopted to reduce NOx emissions, then NOx reduction is achieved, but combustion oscillation increases causing high-cycle fatigue and potential damage to combustor components
Solution Approach 1:
The patent applies beforehand cushioning by designing a containment structure (combustor component or shroud) with sufficient structural strength and rigidity to withstand and absorb the effects of combustion oscillation and potential fuel nozzle breakage before damage occurs. This preventive design approach ensures that even if the fuel nozzle breaks due to high-cycle fatigue from oscillation stress, the broken pieces cannot scatter downstream and damage other combustor components, thus cushioning against the harmful effects of combustion oscillation.
2Power
If fuel nozzle is subjected to oscillation stress from premixed combustion, then combustion oscillation occurs, but the fuel nozzle may break and scatter pieces downstream causing damage
Solution Approach 1:
The patent introduces an intermediary containment structure (combustor component or shroud) that acts as a barrier between the fuel nozzle and the downstream combustor components. This intermediary structure prevents direct interaction between broken fuel nozzle pieces and other combustor components, thereby eliminating the harmful effect of downstream scattering while allowing the combustion oscillation to occur.
3Ease of manufacture
If the fuel nozzle has a welded joint with the end flange, then assembly is simplified, but the welded part becomes a weak point susceptible to breakage under oscillation stress
Solution Approach 1:
The patent applies beforehand cushioning by designing a containment structure with sufficient structural strength to compensate for the potential weakness of the welded joint. The containment structure is designed to withstand the oscillation stress and prevent damage propagation, thereby cushioning against the vulnerability of the welded joint while maintaining the simplicity of assembly.
Data Source
Figure 1~2
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Figure 6~7
AI summary
A fuel nozzle for gas turbine combustor of the present invention includes a diffusion combustion burner 13 including a diffusion fuel nozzle 3, a premixing combustion burner 11 including a premixing fuel nozzle 1, an end flange 7 to which the diffusion combustion burner 13 and the premixing combustion burner 11 are mechanically joined, and a diffusion combustion burner support 12 which fixes the diffusion combustion burner 13 to the end flange 7 and is mounted around the premixing fuel nozzle 1 in a manner to cover a root portion 21 of the premixing fuel nozzle 1, the root portion 21 being a junction between the premixing fuel nozzle 1 and the end flange 7. An outside diameter of the premixing fuel nozzle 1 longitudinally varies in a manner to progressively increase toward the junction. A maximum diameter of the root portion 21 of the premixing fuel nozzle 1 is greater than an inside diameter of a hole 12a formed in the diffusion combustion burner support 12.