Multi-Staged Turbine Combustor for Low NOx Emissions
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Solution Overview
Problem
Current turbine engine combustor designs face challenges in balancing low fuel burn, CO2 emissions, and NOx emissions across various power operations, requiring improved fuel and air placement, stoichiometry, and residence time while maintaining operability and reducing NOx formation.
Innovation Solution
A multi-staged combustor design incorporating radial and axial staging with a main combustion chamber and a secondary combustion chamber, featuring angled mixing assemblies and swirlers to create recirculation zones, which injects combustion gases from the secondary chamber into the main chamber for improved mixing and reduced NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional combustor design is used, then the engine can maintain simple structure and ease of manufacture, but it cannot achieve sufficient NOx reduction below CAEP/11 regulations
Solution Approach 1:
The combustor is divided into multiple distinct zones including a primary combustion zone with fuel-rich mixture and a secondary combustion zone with fuel-lean mixture. This segmentation allows different regions to perform specialized functions: the primary zone generates heat while the secondary zone completes combustion with excess air to minimize NOx formation, thereby resolving the contradiction between emission reduction and structural simplicity.
Solution Approach 2:
Different regions of the combustor are designed with locally optimized characteristics: the primary combustion zone uses a fuel-rich mixture (equivalence ratio greater than 1.0) to promote complete fuel oxidation, while the secondary combustion zone uses a fuel-lean mixture (equivalence ratio less than 1.0) with excess air to reduce peak temperatures and suppress NOx formation. This local differentiation enables the combustor to achieve low NOx emissions without requiring complex external control systems.
2Productivity
If fuel-air mixing is optimized for complete combustion, then combustion efficiency improves, but residence time increases leading to higher NOx formation
Solution Approach 1:
The combustion process is segmented into two sequential stages: first, the primary combustion zone rapidly oxidizes fuel in a fuel-rich environment to achieve high combustion efficiency and release most of the energy; second, the secondary combustion zone introduces excess air to complete the oxidation of remaining fuel and combustion products. This segmentation allows the system to achieve both high combustion efficiency and low NOx emissions by avoiding prolonged exposure of fuel to high temperatures with excess air present.
Solution Approach 2:
The primary combustion zone performs the preliminary combustion action by oxidizing the majority of fuel under fuel-rich conditions before the secondary zone introduces excess air. This preliminary combustion reduces the fuel load and temperature before the final combustion stage, preventing the formation of thermal NOx that would occur if excess air were present throughout the entire combustion process.
3Loss of substance
If fuel-rich mixture is used to improve combustion efficiency, then fuel burn reduces, but incomplete combustion increases CO and unburned hydrocarbon emissions
Solution Approach 1:
The combustor segments the combustion process into a primary zone with fuel-rich mixture for efficient fuel oxidation and a secondary zone with fuel-lean mixture for complete combustion. The primary zone's fuel-rich conditions promote rapid heat release and fuel consumption, while the secondary zone's excess air ensures complete oxidation of any remaining fuel, CO, and unburned hydrocarbons, thereby achieving both low fuel burn and low harmful emissions.
Solution Approach 2:
The combustion process continues uninterrupted from the primary zone through the secondary zone, with the secondary zone acting as a continuation of the combustion process rather than a separate stage. This continuous combustion action ensures that any incomplete combustion products from the primary zone are fully oxidized in the secondary zone, eliminating CO and unburned hydrocarbon emissions while maintaining the fuel efficiency benefits of the initial fuel-rich combustion.
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 multi-staged combustor achieves significant NOx reduction (at least 50% below CAEP/11 regulations) by optimizing fuel-air ratios and residence times, enhancing combustion efficiency and operability across the entire mission cycle of a turbine engine.
Implementation Method 1
A turbine engine includes a multi-staged combustor with a main combustion chamber and a secondary combustion chamber... the pilot mixer injecting a pilot mixer fuel-air mixture into the main combustion chamber... the main mixer injecting a main mixer fuel-air mixture into the secondary combustion chamber... to produce combustion gases
Implementation Method 2
A turbine engine includes a multi-staged combustor with a main combustion chamber and a secondary combustion chamber... featuring angled mixing assemblies and swirlers to create recirculation zones, which injects combustion gases from the secondary chamber into the main chamber for improved mixing
Data Source
AI summary
A turbine engine includes a combustor having a main combustion chamber, an annular dome positioned at a first angle α with respect to a longitudinal centerline axis of the combustor, and a secondary combustion chamber. The secondary combustion chamber is defined by a portion of the annular dome and an aft wall positioned at a second angle β with respect to the longitudinal centerline axis. A pilot mixer is disposed through the annular dome and injects a pilot mixer fuel-air mixture at a pilot mixer fuel-air mixture angle into the main combustion chamber and generates a first recirculation zone. A main mixer is disposed through the aft wall or the annular dome at the secondary combustion chamber. The main mixer injects a main mixer fuel-air mixture at a main mixer fuel-air mixture angle into the secondary combustion chamber to produce combustion gases and generates a second recirculation zone.