Gas Turbine Combustor Local Fuel Injection Ignition
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Solution Overview
Problem
Gas turbine combustors face challenges in reducing NOx emissions and achieving efficient ignition, particularly during low-output operations, due to irregular fuel distribution and the complexity of igniter mechanisms, which increase weight and cost.
Innovation Solution
The combustor incorporates a hybrid fuel injection system with pilot and main nozzles for diffusion and premixed combustion modes, respectively, and includes a local fuel injection port to create a combustible fuel mixture zone near the igniter, ensuring reliable ignition with reduced NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffusion combustion system is used with irregular fuel distribution, then ignition performance is improved, but NOx emissions increase due to high-temperature regions
Solution Approach 1:
The patent applies local quality by creating a rich fuel mixture zone specifically in the vicinity of the igniter through local fuel injection, while the rest of the combustor operates with lean premixed combustion. This localized rich zone ensures reliable ignition without requiring irregular fuel distribution throughout the entire combustor, thereby reducing NOx emissions in other regions.
Solution Approach 2:
The patent uses preliminary action by pre-mixing fuel and air in a lean mixture before combustion, then locally enriching the mixture near the igniter just before ignition occurs. This allows the system to start with uniform lean mixing (low NOx potential) and only create rich conditions where and when needed for ignition.
2Object-generated harmful factors
If a lean premixed combustion system is used with uniform fuel distribution, then NOx emissions are reduced, but combustion stability deteriorates during low-output operations
Solution Approach 1:
The patent maintains lean premixed combustion throughout most of the combustor for low NOx emissions, but introduces a localized rich fuel injection zone near the igniter. This local enrichment provides the necessary combustion stability during low-output operations without compromising the overall lean burn regime that reduces NOx emissions.
Solution Approach 2:
The patent segments the combustor into two functional zones: a lean premixed combustion zone for low NOx emissions and a local rich fuel injection zone near the igniter for combustion stability. This segmentation allows each zone to optimize its function independently.
3Reliability
If complex igniter mechanisms are used to improve ignition reliability, then ignition performance is enhanced, but device weight and cost increase
Solution Approach 1:
The patent makes the fuel injection system self-serving for ignition purposes by creating a rich fuel mixture zone automatically in the vicinity of the igniter through the local fuel injection port. This eliminates the need for complex igniter mechanisms to move or adjust, as the fuel preparation is handled autonomously by the injection system.
Solution Approach 2:
The patent introduces a local fuel injection port as an intermediary between the main fuel injection system and the igniter. This intermediary creates the necessary rich fuel zone near the igniter, simplifying the igniter's task and allowing it to be a simpler, more reliable device.
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
This solution enhances ignition performance and reduces NOx emissions by stabilizing flames and optimizing fuel distribution, while simplifying the igniter mechanism to reduce weight and cost.
Implementation Method 1
The fuel delivered by the diffusion fuel nozzle is diffused and mixed into part of the air flowed into the combustor
Implementation Method 2
The combustible fuel mixture zone is ignited by the igniter
Data Source
AI summary
A gas turbine combustor burns a fuel mixture at a high combustion efficiency and a low NOx emission, is simple in construction and exercises improved ignition performance, and an ignition method can efficiently igniting a fuel mixture in the gas turbine combustor. A gas turbine combustor provided with fuel nozzles each having a pilot fuel injection nozzle and a main fuel injection nozzle, and fuel nozzles each having a pilot fuel injection nozzle and a main fuel injection nozzle. The fuel nozzle disposed close to an igniter is provided with a local fuel injection port through which fuel is jetted out from a predetermined position in an air passage in the main fuel injection nozzle to create a combustible fuel mixture zone in the vicinity of the igniter at least while the igniter is in an ignition operation.