Segmented Combustor Layout for Low-NOx Turbomachines
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Solution Overview
Problem
Existing combustion systems face challenges in sustaining high working temperatures while minimizing the time combustion gases spend at peak temperatures, leading to excessive nitrogen oxide (NOx) emissions.
Innovation Solution
A combustor design featuring a bundled tube fuel nozzle assembly and multiple fuel injectors, which create distinct combustion zones with optimized lengths and temperatures to minimize the duration of high-temperature exposure, utilizing a non-swirling, laminar flow of fuel-air mixtures to reduce NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high working temperature is sustained from combustion chamber to combustor exit, then optimal work production in turbine is achieved, but nitrogen oxide emissions increase exponentially
Solution Approach 1:
The combustion zone is divided into multiple segments with different fuel injection points (upstream, mid, and downstream injectors) and distinct combustion zones. This segmentation allows different portions of the combustion process to occur at different locations and time durations, reducing the overall time combustion gases spend at peak temperatures while maintaining sufficient energy for turbine work.
Solution Approach 2:
Fuel is injected in periodic pulses through multiple injectors rather than continuously in a single zone. The controlled pulsing of fuel injection creates periodic combustion events that limit the duration of high-temperature exposure, thereby reducing NOx formation while still delivering adequate thermal energy to the turbine.
2Power
If combustion zone length is extended to sustain high temperature, then turbine work output improves, but time at peak temperature increases and NOx emissions worsen
Solution Approach 1:
The combustion process is segmented into multiple zones along the combustor length, with each zone contributing to the overall energy release. This allows the combustion to be distributed over space rather than concentrated in a single extended zone, reducing the time gases spend at peak temperatures while maintaining total energy output for turbine work.
Solution Approach 2:
Fuel is pre-mixed with air in controlled ratios before injection into the combustion zone. This preliminary mixing ensures efficient and rapid combustion that completes in shorter duration, reducing time at peak temperature while still achieving the necessary energy release for turbine work production.
3Object-generated harmful factors
If multiple fuel injectors are added to create distinct combustion zones, then NOx emissions are reduced through minimized high-temperature exposure time, but device complexity increases
Solution Approach 1:
The combustor is segmented into multiple combustion zones with separate fuel injectors for each zone. This segmentation enables independent control of fuel injection timing and location, allowing optimization of each zone to minimize high-temperature residence time and reduce NOx emissions while maintaining a manageable overall structure through modular design.
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 achieves a significant decrease in NOx emissions by shortening combustion zone lengths and reducing the time combustion gases spend at high temperatures, enhancing operational efficiency and emissions control.
Implementation Method 1
The mixed working fluid and fuel are ignited at a generally upstream portion of the combustor, i.e. within the combustion chamber, to generate a working turbine operating temperature
Implementation Method 2
utilizing a non-swirling, laminar flow of fuel-air mixtures to reduce NOx emissions
Data Source
AI summary
Combustors, gas turbines, and associated methods of operation are provided. A method for operating a combustor includes firing a bundled tube fuel nozzle assembly within a combustion liner of the combustor to generate combustion gases at a first temperature within a first combustion zone length. The method further includes firing a fuel injector downstream from the bundled tube fuel nozzle assembly within the combustion liner of the combustor to generate combustion gases at a second temperature within a second combustion zone length. The first combustion zone length is less than the second combustion zone length. The combustion gases travel through the first combustion zone length in a first time period and through the second combustion zone length in a second time period. The second time period is less than the first time period.