Premixed Burner Cross-Section Reduction for Flashback Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current gas turbine burners face challenges in achieving high efficiency while minimizing NOx emissions and life cycle costs, particularly when operating with high reactivity fuels, as they require high turbine inlet temperatures and struggle with flashback and thermo acoustic pulsations.
Innovation Solution
A premixed burner design with an injection device featuring a streamlined body and vortex generators for rapid fuel-air mixing, where the cross-sectional area is reduced downstream to increase flow velocity, allowing for efficient mixing and flame stabilization without significant pressure drop, suitable for both annular and can-annular combustors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the cross-sectional area is reduced downstream to increase flow velocity, then rapid fuel-air mixing is achieved, but burner pressure drop increases
Solution Approach 1:
The burner is divided into distinct sections: a first section with a first cross-sectional area for fuel injection and mixing, and a second section with a second cross-sectional area for combustion. This segmentation allows each section to be optimized independently - the first section promotes rapid mixing through appropriate geometry while the second section manages pressure drop and combustion efficiency
Solution Approach 2:
Different cross-sectional areas are provided in different locations along the burner. The first cross-sectional area at the fuel injection zone promotes rapid mixing and high flow velocity, while the second cross-sectional area downstream supports combustion with lower pressure drop. This local variation in geometry optimizes both mixing speed and pressure characteristics
2Productivity
If high turbine inlet temperature is used to achieve high efficiency, then productivity increases, but NOx emissions increase
Solution Approach 1:
Fuel and air are mixed preliminarily in the first section of the burner before combustion occurs. This pre-mixing ensures complete combustion and optimal air-fuel ratio, which prevents incomplete combustion products and reduces thermal NOx formation. The mixing zone is designed to achieve rapid mixing, ensuring that combustion occurs efficiently at high temperatures without excessive NOx
Solution Approach 2:
The burner geometry parameters (cross-sectional areas, lengths, vortex generator angles) are optimized to control the mixing process. By adjusting these parameters, the residence time of fuel-air mixture is controlled, and mixing quality is enhanced, allowing high temperature operation with reduced NOx emissions through better combustion chemistry control
3Productivity
If high reactivity fuels are burned to increase energy density, then productivity increases, but flashback and thermo acoustic pulsations occur
Solution Approach 1:
The burner performs preliminary mixing of fuel and air in a controlled environment before the mixture enters the combustion zone. This pre-mixing ensures that highly reactive fuels like hydrogen or synthetic gases are properly diluted and prepared, preventing flashback into the burner and reducing thermo-acoustic pulsations. The mixing zone acts as a buffer that stabilizes the combustion process
Solution Approach 2:
The burner design incorporates geometric features (cross-sectional area variations, vortex generators) that create a cushioning effect in the mixing zone. This cushioning absorbs the high reactivity of the fuel-air mixture, preventing premature ignition and flashback. The residence time in the mixing zone is optimized to allow controlled mixing without creating conditions for thermo-acoustic instability
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 rapid fuel-air mixing with lower residence times, accommodating highly reactive fuels and high inlet temperatures while maintaining low NOx emissions and preventing flashback, thus enhancing operational flexibility and efficiency.
Implementation Method 1
at and/or downstream of said body the cross-sectional area is reduced, such that the first cross-sectional area is larger than the second cross-sectional area. This reduction of the cross-section typically leads to an increase of the flow velocity along this flow path
Implementation Method 2
The design preferably features aerodynamically facilitated axial fuel injection with mixing enhancement via small sized vortex generators
Implementation Method 3
a part of the fuel is combusted. After expanding at the high-pressure turbine stage, the remaining fuel is added and combusted
Data Source
Figure 1~2
Figure 3a~3e
Figure 3f~3g
AI summary
The disclosure relates to a burner (1) for a single combustion chamber or first combustion chamber of a gas turbine, with an injection device (7) for the introduction of at least one gaseous and/or liquid fuel into the burner (1), wherein the injection device (7) has at least one body (22) which is arranged in the burner (1) with at least one nozzle (15) for introducing the at least one fuel into the burner (1), wherein the at least one body (22) is located in a first section (18) of the burner (1) with a first cross-sectional area at a leading edge of the at least one body (22) with reference to a main flow direction (14) prevailing in the burner (1), wherein downstream of said body (22) a mixing zone (2) is located with a second cross-sectional area, and at and/or downstream of said body (22) the cross-sectional area is reduced, such that the first cross-sectional area is larger than the second cross-sectional area.