Gas Turbine Combustor Air Introduction Passages Ignition
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Solution Overview
Problem
Gas turbine combustors face challenges in improving starting ignition characteristics and flame propagation while reducing NOx emissions during premixed combustion, as the fuel-air mixture tends to homogenize, leading to decreased ignition and flame propagation efficiency.
Innovation Solution
The combustor design includes a burner with a mixing chamber wall featuring axially and circumferentially offset air introduction passages that direct fuel and air flows towards the spark plug and cross-fire tubes, enhancing fuel concentration and mixing, thereby improving ignition and flame propagation characteristics, and reducing NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel and air are mixed in the mixing chamber to achieve premixed combustion for NOx reduction, then NOx emissions are reduced, but the fuel concentration becomes homogenized which decreases ignition and flame propagation characteristics
Solution Approach 1:
The patent introduces a specific air introduction passage that is axially and circumferentially offset from other passages, creating localized variations in fuel concentration within the mixing chamber. This offset passage directs combustion air and fuel jet flows toward the spark plug and cross-fire tube, ensuring high fuel concentration at ignition critical areas while maintaining overall premixed combustion for NOx reduction.
Solution Approach 2:
The air introduction system is segmented into multiple passages with different orientations and positions. The specific offset air introduction passage is separated from other passages to independently control fuel-air mixing characteristics, allowing different regions of the mixing chamber to have different fuel concentrations optimized for their specific functions.
2Reliability
If fuel concentration is increased to improve ignition characteristics, then starting ignition characteristics improve, but NOx emissions increase due to less effective premixed combustion
Solution Approach 1:
The offset air introduction passage creates a localized high fuel concentration zone at the spark plug and cross-fire tube regions, improving ignition characteristics without requiring overall fuel concentration increase. This localized enrichment maintains effective premixed combustion in other regions, keeping NOx emissions low.
3Productivity
If multiple air introduction passages are added to improve mixing, then fuel-air mixing is accelerated, but device complexity increases
Solution Approach 1:
The mixing chamber wall is segmented into multiple air introduction passages, each serving specific functions. The passages are arranged in different rows (first row and second row) with different orientations, allowing efficient fuel-air mixing through structured segmentation rather than random complexity.
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 design accelerates fuel-air mixing, improves ignition and flame propagation, and reduces NOx emissions by creating a higher fuel concentration at critical areas, leading to better starting ignition characteristics and extended operational load ranges for the gas turbine.
Implementation Method 1
a plurality of air introduction passages installed in the mixing chamber wall each for introducing combustion air, along with the fuel from the fuel nozzle, into the mixing chamber
Implementation Method 2
mixing of the fuel and air in the air introduction passages and in the mixing chamber is accelerated
Implementation Method 3
at least one specific air introduction passage among the air introduction passages is formed in axially and circumferentially offset form such that flows of the combustion air and fuel jetted from the specific air introduction passages into the mixing chamber are directed towards at least one of the spark plug or the cross-fire tube
Implementation Method 4
a spark plug for igniting the mixture
Implementation Method 5
a cross-fire tube for propagating between the combustors a flame formed by the combustion of the mixture
Implementation Method 6
combustion gases resulting from combustion of a fuel-air mixture
Data Source
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AI summary
In a gas turbine combustor, mixing of a fuel and air is accelerated in a mixing chamber of a burner as well as in air introduction passages provided in a wall of the mixing chamber, whereby NOx emissions from premixed combustion are reduced while at the same time, ignition characteristics and flame propagation characteristics improve. The gas turbine combustor includes a plurality of combustors 10, a spark plug 13, and a cross-fire tube 15 that propagates a flame between the combustors 10. Each combustor 10 includes the burner 30 equipped with a fuel nozzle and the mixing chamber wall 32 forming the mixing chamber 31. A plurality of air introduction holes 35, 36 for introducing combustion air, along with the fuel from the fuel nozzle, into the mixing chamber 31, are provided in the mixing chamber wall 32. The combustion air and fuel jetted from the air introduction hole 35 into the mixing chamber 31 are mixed in the form of a mixture "m1" , "m2" and directed towards the spark plug 13 and the cross-fire tube 15.