Gas Turbine Combustor Staging for Lower NOx Emissions
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Solution Overview
Problem
Existing combustion systems in gas turbine engines face challenges in minimizing the time combustion gases spend at peak temperatures, leading to excessive nitrogen oxide (NOx) emissions due to the exponential relationship between temperature and NOx generation.
Innovation Solution
A bundled tube fuel nozzle assembly is used within a combustion liner, followed by downstream fuel injectors, creating distinct combustion zones with varying temperatures and lengths to optimize combustion time and 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 combustor is divided into multiple combustion zones with different temperature levels. The first combustion zone operates at higher temperature for efficient work production, while the second combustion zone operates at lower temperature to minimize NOx formation. This segmentation allows the system to achieve both optimal power output and reduced emissions by spatially separating the combustion processes.
2Power
If combustion zone length is extended to sustain high temperature, then work production is optimized, but time at peak temperature increases leading to more NOx
Solution Approach 1:
The combustion process is segmented into two distinct zones: a first combustion zone that is shorter in length and operates at higher temperature for rapid energy release, and a second combustion zone that is longer in length but operates at lower temperature. This segmentation reduces the total time combustion gases spend at peak temperatures while still achieving optimal work production through the combined effect of both zones.
Solution Approach 2:
The combustion process utilizes periodic or staged action by sequentially activating different fuel nozzles and burners. The first stage combustion provides initial high-temperature energy release, followed by the second stage combustion at reduced temperature. This staged approach minimizes the duration of peak temperature exposure while maintaining effective work production throughout the combustor length.
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 method minimizes the time combustion gases spend at high temperatures, resulting in a significant decrease in nitrogen oxide emissions by ensuring a laminar flow and quick combustion, thus enhancing the efficiency and reducing NOx production.
Implementation Method 1
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; 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
Data Source
Figure 1~2
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AI summary
A method for operating a combustor (14) includes firing a bundled tube fuel nozzle assembly (100) within a combustion liner (36) of the combustor (14) to generate combustion gases (26) at a first temperature within a first combustion zone length (92). The method further includes firing a fuel injector (60) downstream from the bundled tube fuel nozzle assembly (100) within the combustion liner (36) of the combustor (14) to generate combustion gases (26) at a second temperature within a second combustion zone length (94). The first combustion zone length (92) is less than the second combustion zone length (94). The combustion gases (26) travel through the first combustion zone length (92) in a first time period and through the second combustion zone length (94) in a second time period. The second time period is less than the first time period.