Removable Pilot Assembly for Gas Turbine Fuel Injector
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Solution Overview
Problem
Gas turbine engines face challenges in reducing NOx emissions while maintaining stable combustion, as existing fuel injectors with permanently attached pilot assemblies are difficult to maintain and replace due to high temperature damage, leading to potential lean blow-out and fuel/air leakage issues.
Innovation Solution
A fuel injector design with a removable pilot assembly, featuring a tubular configuration with concentric components and screw threads for easy coupling and decoupling, allowing for the replacement of damaged components without replacing the entire injector, thereby preventing fuel and air leakage and facilitating maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pilot assembly is permanently attached to the injector structure, then fuel and air leakage is prevented, but replacement of damaged pilot components becomes difficult in field environment
Solution Approach 1:
The pilot assembly is divided into separate components (pilot tube, pilot cap, sealing elements) that can be independently replaced. The pilot tube is removable from the injector body through threaded connections, allowing field replacement of damaged components without replacing the entire injector assembly, while maintaining sealing integrity through dedicated sealing elements at connection interfaces.
2Object-generated harmful factors
If the fuel content in the fuel-air mixture is reduced to meet NOx regulations, then NOx emissions are reduced, but the flame becomes unstable and may cause lean blow-out
Solution Approach 1:
The fuel injection system is segmented into a main fuel stream (lean premixed) and a pilot fuel stream (rich). The pilot fuel stream provides a stable combustion core that prevents lean blow-out while the main lean stream controls NOx emissions, allowing the system to meet emission regulations while maintaining flame stability.
3Reliability
If the entire fuel injector is replaced when pilot components are damaged, then reliable combustion is restored, but maintenance cost and time increase
Solution Approach 1:
The pilot assembly components are designed as removable and replaceable units. When the pilot tube or related components show signs of high-temperature damage, only these specific components need to be replaced rather than the entire injector, significantly reducing maintenance time and cost while restoring reliable combustion.
Solution Approach 2:
Damaged pilot components (pilot tube, pilot cap) can be discarded and replaced with new or refurbished components. The removable design allows these components to be individually recovered or replaced without wasting the rest of the functional injector assembly, optimizing resource utilization and reducing maintenance expenses.
Data Source
AI summary
A fuel injector for a gas turbine engine is disclosed. The fuel injector includes an injector housing having a longitudinal axis. The injector housing includes one or more fuel inlets, one or more fuel galleries annularly disposed about the longitudinal axis, and an air inlet. The fuel injector also includes a premix barrel having a proximal end and a distal end circumferentially disposed about the longitudinal axis. The premix barrel is fluidly coupled to the fuel galleries and the air inlet at the proximal end, and configured to mechanically couple to a combustor of the gas turbine engine at the distal end. The fuel injector also includes a pilot assembly disposed radially inwards of the premix barrel. The pilot assembly may include a first end and a second end. The second end is removably coupled to the injector housing, and the first end is proximate the distal end of the premix barrel. The pilot assembly is fluidly coupled to the fuel galleries, the air inlet, and the combustor.