Fuel Nozzle Premix Plate for Uniform Mixing and Flame Stabilization
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Solution Overview
Problem
Current fuel nozzle assemblies for gas turbines face challenges in achieving uniform flow fields and flame stabilization, leading to increased NOx emissions due to high combustion gas temperatures, which are exacerbated by non-uniform mixing of fuel and air.
Innovation Solution
A fuel nozzle assembly with a premix chamber defined by arcuate inner and outer walls, an air flow divider, guide vanes with fuel ports, and a premix plate that extends radially and circumferentially, providing a plurality of passages for fluid flow, which ensures uniform mixing and flame stabilization by manipulating the flow characteristics and promoting complete premixing of the fuel-air mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional fuel nozzle assemblies are used, then fuel injection is simple, but flow field uniformity and flame stabilization are poor leading to high NOx emissions
Solution Approach 1:
The fuel nozzle assembly is segmented into multiple functional zones: a premixing zone with multiple injection points, a stabilization zone with a flame holder, and a combustion zone. This segmentation allows each zone to perform its specific function optimally, achieving uniform mixing and flame stabilization while controlling NOx emissions
Solution Approach 2:
A premixing chamber acts as an intermediary between fuel injection and combustion. This intermediate zone allows fuel and air to mix uniformly before entering the combustion zone, preventing direct combustion of rich mixtures that would generate high NOx emissions
2Temperature
If fuel and air are not pre-mixed uniformly, then injection is simple, but combustion gas temperature increases leading to higher NOx formation
Solution Approach 1:
Fuel and air are pre-mixed in a dedicated premixing chamber before combustion occurs. This preliminary mixing action ensures uniform composition of the combustible mixture, leading to more uniform combustion and lower peak temperatures that reduce NOx formation
Solution Approach 2:
The premixing process utilizes fluid dynamics principles where compressed air flows through the premixing chamber and mixes with injected fuel. The pneumatic flow patterns created by the chamber geometry and injection points ensure thorough mixing while controlling the temperature of the mixture before combustion
3Manufacturing precision
If a premix plate with passages is added, then fuel-air mixing is uniform, but device complexity increases
Solution Approach 1:
The premixing chamber integrates multiple functions into a single component: it serves as the mixing zone, houses the flame holder, and provides flow distribution. This merging of functions achieves uniform flow field characteristics without requiring separate components for each function, thereby limiting the increase in device 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
The solution effectively reduces NOx emissions by ensuring uniform fuel-air mixing and flame stability, thereby lowering combustion gas temperatures and improving emissions performance.
Implementation Method 1
The passages provide for fluid flow from the premix chamber through the premix plate
Implementation Method 2
ensures uniform mixing and flame stabilization by manipulating the flow characteristics and promoting complete premixing of the fuel-air mixture
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A fuel nozzle assembly (100) includes a premix chamber (114), an air flow divider (116) extending radially and axially within the premix chamber (114) between an inner wall (102) and an outer wall (104) and a plurality of guide vanes (122) disposed within the premix chamber (114). One or more of the guide vanes (122) includes a fuel port (130) in fluid communication with the flow divider (116). The fuel nozzle assembly (100) further includes a premix plate (110) that extends radially between the inner and outer walls (102), (104) and circumferentially between first and second side walls (106), (108) downstream from the fuel ports (130). The premix plate (110) includes an upstream side (142) axially spaced from a downstream side (144) and a plurality of passages (146) that provide for fluid flow from the premix chamber (114) through the premix plate (110).