Gas Turbine Combustor Tapered Nozzle Flashback Prevention
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Solution Overview
Problem
Gas turbine combustors face challenges in reducing NOx emissions when using hydrogen-containing fuels, particularly due to high combustion velocities and flashback risks, which can lead to reliability issues and inefficient power generation.
Innovation Solution
A gas turbine combustor design featuring an air hole plate with concentrically arranged air holes and fuel nozzles with tapered shapes to enhance mixing and prevent flashback, including a fuel nozzle inner wall with a tapered shape extending outward and an air hole with a tapered shape to increase air flow velocity and reduce low flow velocity regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diffusion combustion type is used, then combustion stability is ensured and flashback is prevented, but NOx emissions are increased due to high-temperature flame formation
Solution Approach 1:
The invention changes the physical parameters of the combustion process by introducing a pre-mixing stage where fuel and air are mixed before combustion. This creates a lean premixed combustion mode that lowers flame temperature and reduces NOx emissions while maintaining combustion stability through controlled mixing ratios and turbulence management.
Solution Approach 2:
The invention performs preliminary mixing of fuel and air in a pre-mixer before they enter the combustion chamber. This pre-mixing action allows the combustion to occur in a leaner, more controlled manner, preventing the formation of high-temperature zones that produce NOx while ensuring stable combustion through uniform mixture distribution.
2Object-generated harmful factors
If premixed combustion type is used, then NOx emissions are reduced through lean combustion, but flashback and auto ignition risks increase with hydrogen-containing fuels
Solution Approach 1:
The invention applies different structural characteristics to different regions of the combustor. The pre-mixer has a specific length-to-diameter ratio and internal structure optimized for mixing, while the combustion chamber has features optimized for stable flame anchoring. This local optimization allows lean premixed combustion without flashback by creating appropriate flow conditions in each zone.
Solution Approach 2:
The invention transitions from a simple single-chamber design to a two-stage system with distinct pre-mixing and combustion zones. This dimensional separation allows independent optimization of mixing and combustion processes, enabling lean premixed combustion while preventing flashback through proper zone separation and flow control.
3Productivity
If turbine inlet temperature is increased, then power generation efficiency is improved, but NOx emissions are increased
Solution Approach 1:
The invention changes the combustion mode from diffusion or simple premixed combustion to lean premixed combustion with controlled turbulence. This parameter change allows the combustion process to operate at higher temperatures for improved efficiency while maintaining lean mixture ratios that suppress NOx formation through lower peak flame temperatures.
4Object-generated harmful factors
If hydrogen-containing fuels are used, then CO2 emissions are reduced, but combustion velocity increases causing flashback risks
Solution Approach 1:
The invention creates specific local flow conditions in the pre-mixer and combustion chamber that are optimized for hydrogen-containing fuels. The pre-mixer length and diameter are configured to provide adequate mixing time while maintaining sufficient flow velocity to prevent flashback. The combustion chamber includes features that anchor the flame and create turbulence that stabilizes combustion without allowing flashback upstream.
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 effectively reduces NOx emissions, improves reliability, and stabilizes combustion, ensuring efficient operation with hydrogen-containing fuels by preventing flashback and maintaining flame stability away from critical components.
Implementation Method 1
fuel nozzles with tapered shapes to enhance mixing and prevent flashback
Implementation Method 2
an air hole with a tapered shape to increase air flow velocity and reduce low flow velocity regions
Implementation Method 3
a combustion chamber which burns a fuel and air
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention provides a gas turbine combustor (3) which reduces NOx emissions for a hydrogen containing fuel, is improved in reliability and realizes stable operation. The gas turbine combustor of the present invention includes a combustion chamber (5) which burns a fuel and air, an air hole plate (20) which is located on an upstream side of the combustion chamber and has air holes (21) which are concentrically arranged plurally in line and plurally in number, and fuel nozzles (22) which are arranged plurally in line and plurally in number, and a fuel nozzle inner wall has a fuel nozzle tapered shape which extends in an outer circumferential direction on a leading end part of the fuel nozzle.