Lean Pre-Nozzle Fuel Injection Combustor Design
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Solution Overview
Problem
Gas turbine engines face challenges in achieving efficient combustion while minimizing nitrogen oxide (NOx) emissions and avoiding issues like flame holding, flashback, and auto-ignition, particularly when using highly reactive fuels.
Innovation Solution
A combustor design featuring a lean pre-nozzle fuel injection system and a premixing annulus between the fuel nozzles and the injection system for improved fuel-air premixing, which includes aerodynamically shaped fuel injectors and a flared premixing annulus to enhance mixing and reduce the risk of flame holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If premixing fuel and air upstream of fuel nozzles is used to reduce NOx emissions, then NOx emissions are reduced, but flame holding and flashback issues occur
Solution Approach 1:
The fuel injection system is segmented into multiple stages: a lean pre-nozzle injection system that injects fuel into the premixing annulus, and separate fuel nozzles positioned downstream. This segmentation allows controlled fuel injection at different locations, preventing flame holding in the premixing region while maintaining effective premixing for NOx reduction.
Solution Approach 2:
The premixing annulus serves as an intermediary region between the lean pre-nozzle injection system and the fuel nozzles. It provides a controlled environment for fuel-air mixing while physically separating the injection zones, preventing direct contact between injected fuel and potential flame sources, thus avoiding flashback and flame holding issues.
2Productivity
If highly reactive fuels are used to improve combustion efficiency, then combustion efficiency increases, but flame holding and auto-ignition risks increase
Solution Approach 1:
The lean pre-nozzle injection system performs preliminary fuel injection into the premixing annulus before the main combustion zone. This preliminary action allows highly reactive fuels to be introduced in a controlled, lean mixture state, preventing premature auto-ignition while maintaining combustion efficiency when the mixture reaches the combustion zone.
Solution Approach 2:
The system changes the fuel mixture parameters by creating a lean mixture in the premixing annulus before combustion. This parameter change (reducing fuel concentration) prevents auto-ignition of highly reactive fuels while maintaining combustion efficiency, as the lean mixture requires higher temperatures to ignite, preventing premature combustion.
3Stability of the object's composition
If multiple fuel nozzles are used to improve mixing, then fuel-air mixing improves, but device complexity increases
Solution Approach 1:
The lean pre-nozzle injection system and the fuel nozzles are merged into a coordinated system where the premixing annulus serves as a common mixing region. This merging allows multiple fuel injection points to work together synergistically, improving overall mixing quality while sharing common structural elements that reduce overall system complexity.
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 reduces NOx emissions, minimizes pressure drop, and increases fuel flexibility, including the use of highly reactive fuels, while maintaining emissions below regulatory levels and preventing operational issues like flame holding and auto-ignition.
Implementation Method 1
a lean pre-nozzle fuel injection system positioned upstream of the fuel nozzles, and a premixing annulus positioned between the fuel nozzles and the lean pre-nozzle fuel injection system to premix the flow of fuel and the flow of air
Data Source
AI summary
The present application provides for a combustor for combusting a flow of fuel and a flow of air. The combustor may include a number of fuel nozzles, a lean pre-nozzle fuel injection system positioned upstream of the fuel nozzles, and a premixing annulus positioned between the fuel nozzles and the lean pre-nozzle fuel injection system to premix the flow of fuel and the flow of air.