Fuel Injection Assembly with Slanted Premix Tubes
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Solution Overview
Problem
Traditional gas turbine combustors with axial fuel staging systems struggle to burn high levels of hydrogen or pure hydrogen without causing flashback or flame holding issues, leading to potential damage and high NOx emissions.
Innovation Solution
A fuel injection assembly for gas turbines that includes a fuel injector coupled to an outer sleeve and a boss configured to couple with a combustion liner, featuring a serpentine cooling passage and premix tubes with slanted injection axes, which effectively mixes hydrogen with air to prevent flashback and reduce NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional AFS fuel injectors are used to burn high levels of hydrogen or pure hydrogen, then hydrogen combustion can be achieved, but flashback or flame holding conditions occur causing damage to the injector
Solution Approach 1:
The patent applies preliminary action by pre-cooling the fuel/air mixture before it enters the combustion zone. The cooling passage is positioned to intercept the mixture upstream, reducing its temperature prior to combustion. This prevents the flame from migrating back toward the injector by ensuring the mixture temperature remains below the ignition threshold, thus eliminating flashback conditions while enabling hydrogen combustion.
Solution Approach 2:
The cooling passage acts as an intermediary element between the fuel delivery system and the combustion zone. It introduces a cooling medium (air or gas) that mediates the temperature of the fuel/air mixture, creating a thermal buffer that prevents direct contact between high-temperature flame and the injector components, thereby protecting the injector while allowing hydrogen combustion.
2Productivity
If traditional combustion systems are used for hydrogen burning, then fuel injection is achieved, but NOx emissions increase due to high temperature combustion
Solution Approach 1:
The patent applies parameter changes by modifying the temperature parameter of the fuel/air mixture through pre-cooling. By reducing the mixture temperature before combustion, the peak combustion temperature is lowered, which directly reduces thermal NOx formation. This allows efficient hydrogen combustion to proceed while controlling the temperature parameter to minimize harmful NOx emissions.
3Adaptability or versatility
If hydrogen is burned in traditional combustion systems, then alternative fuel utilization is achieved, but flame holding conditions cause severe damage to the injector
Solution Approach 1:
The patent applies preliminary anti-action by taking counter-measures before the harmful effect occurs. The cooling passage is positioned to pre-cool the mixture upstream, creating a temperature barrier that prevents flame migration toward the injector. This proactive cooling action counteracts the tendency of hydrogen flames to hold and migrate, eliminating the risk of flashback damage before it can occur.
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 enables safe and efficient combustion of hydrogen fuels by preventing flashback and significantly reducing NOx emissions, enhancing the durability and environmental performance of gas turbine combustors.
Implementation Method 1
The boss defines a serpentine cooling passage that extends from an inlet on the flange portion to an outlet on the interior surface
Implementation Method 2
premix tubes with slanted injection axes, which effectively mixes hydrogen with air to prevent flashback and reduce NOx emissions
Implementation Method 3
an AFS fuel injector located at a position downstream of the primary fuel nozzle injects fuel and air (or a second fuel/air mixture) as a cross-flow into a secondary combustion zone
Data Source
AI summary
Fuel injection assemblies and combustors are provided. A fuel injection assembly includes a boss that forms at least a portion of an annular wall. The annular wall defines a mixing channel that extends along a center axis. The fuel injection assembly further includes a fuel injector that has a radially outer wall and a radially inner wall that at least partially defines a fuel plenum. The fuel injector further includes a plurality of premix tubes that each extend along an injection axis from an inlet end on the radially outer wall through the fuel plenum to an outlet end, and wherein the injection axis is slanted towards the center axis of the mixing channel.