Fuel Nozzle Baffle Plate for Uniform Premixing
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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 combustible mixtures exiting the premix passage.
Innovation Solution
The fuel nozzle assembly incorporates a baffle plate with radially extending passages and a converging center body design, which creates a uniform fuel-air mixture and stabilizes the flame by maximizing the area for fuel-air flow through the baffle plate, reducing the likelihood of flame holding and enhancing premixing, thereby controlling NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional fuel nozzle assembly is used, then the structure is simple, but the flow field is non-uniform and flame stabilization is poor leading to high NOx emissions
Solution Approach 1:
The fuel nozzle assembly is divided into multiple functional components: a body with a premix passage for fuel-air mixing, and a separate baffle plate with radially extending passages for flow conditioning. This segmentation allows each component to be optimized independently - the premix passage for thorough mixing and the baffle plate for creating a uniform flow field, thereby reducing NOx emissions while maintaining manageable structural complexity
Solution Approach 2:
The baffle plate acts as an intermediary component between the premix passage and the combustion chamber. It receives the premixed fuel-air mixture and conditions it through its radially extending passages to create a uniform flow field before entering the combustion chamber. This intermediary structure stabilizes the flame and ensures complete combustion, preventing the formation of NOx emissions without requiring direct modification of the combustion chamber itself
2Object-generated harmful factors
If fuel and air are premixed in an annular passage, then emissions are reduced, but the flow field uniformity is poor causing flame holding issues
Solution Approach 1:
The baffle plate features radially extending passages that create locally optimized flow conditions. Each radial passage distributes the premixed fuel-air mixture uniformly in the radial direction, ensuring that every local region of the flow field receives a consistent mixture. This local quality control throughout the baffle plate structure achieves overall flow field uniformity, stabilizing the flame and preventing emissions without compromising the premixing benefit
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 a more uniform fuel-air mixture and stable flame, reducing NOx emissions by ensuring complete premixing and minimizing flame holding, thus improving the emissions performance of gas turbines.
Implementation Method 1
fuel is injected into a flow of compressed air within an annular flow or premix passage defined within the fuel nozzle assembly. The fuel and compressed air mixes within the annular passage
Implementation Method 2
a converging center body design, which creates a uniform fuel-air mixture and stabilizes the flame by maximizing the area for fuel-air flow through the baffle plate
Implementation Method 3
the heat capacity or thermal capacitance of excess air present in the air-rich or fuel-lean combustible mixture absorbs heat in the combustion chamber, thus reducing the temperature of the combustion gases, thereby decreasing or preventing the formation of NOx emissions
Data Source
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AI summary
A fuel nozzle assembly for use in a gas turbine includes a center body, an outer tube that at least partially surrounds the center body, a premix flow passage that is defined radially between the center body and the outer tube, and a plurality of fuel ports that is disposed between the center body and the outer tube within the premix flow passage. The fuel nozzle assembly also includes a baffle plate that extends radially outwardly from the center body to the outer tube across a downstream end portion of the fuel nozzle assembly. The baffle plate includes an upstream side that is axially spaced from a downstream side and a plurality of passages. The passages provide for fluid flow from the premix flow passage through the baffle plate.