Hybrid Staged Combustor for Turbine Engine NOx Reduction
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Solution Overview
Problem
Current turbine engine combustor designs face challenges in balancing NOx, nvPM, and CO2 emissions across various power operations, requiring improved fuel and air placement, stoichiometry, and residence time while maintaining performance and operability.
Innovation Solution
A hybrid staged combustor system incorporating radial and axial staging with a nested flame structure and auxiliary flame, utilizing multiple mixing assemblies to optimize fuel-air ratios and reduce NOx emissions, achieved through a combination of pilot, main, and auxiliary mixers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional combustor designs are used, then basic combustion function is maintained, but NOx emissions cannot be reduced below regulatory limits
Solution Approach 1:
The combustor is divided into multiple combustion zones (primary combustion zone with pilot mixer, secondary combustion zone with first main mixer, and tertiary combustion zone with second main mixer) arranged axially in sequence. Each zone has dedicated fuel injectors and mixers that operate independently, allowing staged combustion to progressively reduce NOx emissions while maintaining overall combustion efficiency
Solution Approach 2:
Different regions of the combustor are designed with distinct fuel-air ratio characteristics: the pilot mixer creates a fuel-rich primary zone for stable ignition, the first main mixer introduces a fuel-lean secondary zone for reduced NOx formation, and the second main mixer provides additional fuel-lean tertiary zone. This spatial variation in fuel-air ratio optimizes emissions control at different locations
2Object-generated harmful factors
If fuel-air ratio is optimized for low NOx emissions, then NOx reductions are achieved, but combustion efficiency and operability may be compromised
Solution Approach 1:
The pilot mixer establishes a stable fuel-rich primary combustion zone before the main combustion process begins. This preliminary combustion zone provides reliable ignition and flame stabilization, ensuring dependable combustor operation across all power settings before the fuel-lean zones engage for NOx reduction
Solution Approach 2:
The three combustion zones operate continuously and simultaneously, with the pilot mixer maintaining stable combustion, the first main mixer providing fuel-lean combustion for NOx reduction, and the second main mixer adding additional combustion. This continuous multi-zone operation ensures both combustion efficiency and emissions control are maintained throughout the entire mission cycle
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 hybrid staged combustor significantly reduces NOx emissions by up to 50% below regulatory limits, maintaining efficient combustion and operability across the entire mission cycle of a turbine engine.
Implementation Method 1
the pilot mixer operably injecting a pilot fuel-air mixture axially into a first combustion zone
Implementation Method 2
the first main mixer operably injecting a first main mixer fuel-air mixture radially into the first combustion zone
Implementation Method 3
the second main mixer operably injecting a second main mixer fuel-air mixture radially into a second combustion zone
Implementation Method 4
The hybrid staged combustor significantly reduces NOx emissions by up to 50% below regulatory limits, maintaining efficient combustion
Data Source
AI summary
A combustor for a turbine engine includes a combustion chamber including an outer liner and an inner liner, and an annular dome. A plurality of first mixing assemblies includes a pilot mixer and a first main mixer, the first mixing assemblies disposed through the annular dome. The pilot mixer injects a pilot mixer fuel-air mixture axially into a first combustion zone, and the first main mixer injects a first main mixer fuel-air mixture radially into the first combustion zone. A plurality of second mixing assemblies includes a second main mixer, the second mixing assemblies being axially aft of the plurality of first mixing assemblies. The second main mixer injects a second main mixer fuel-air mixture radially into a second combustion zone that is axially aft of, and separate from, the first combustion zone.