Angled Fuel Injection Nozzle for Gas Turbine Flashback Prevention
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Solution Overview
Problem
Gas turbines burning conventional hydrocarbon fuels produce high levels of NOx emissions due to the challenges of flame holding and flashback in premixed hydrogen or syngas combustion, which damages nozzle designs and increases NOx production.
Innovation Solution
A fuel/air mixing tube with a premixed direct injection nozzle design featuring fuel injection holes at an angle of 20 to 90 degrees and a recession distance 5 to 100 times the hole diameter, ensuring efficient mixing with low NOx emissions and resistance to flame holding and flashback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If premixed hydrogen or syngas combustion is used to control NOx emissions, then NOx emissions are reduced, but flame holding and flashback problems occur causing nozzle damage
Solution Approach 1:
The fuel injection holes are positioned at a recession distance of 5 to 100 times the hole diameter from the tube exit, creating a pre-mixed fuel-air mixture before the mixture reaches the combustion zone. This preliminary mixing occurs in a controlled manner that prevents flashback while maintaining low NOx emissions
Solution Approach 2:
The fuel injection holes are oriented at specific angles (20 to 90 degrees) relative to the tube axis, creating localized injection patterns that optimize mixing while preventing flame propagation back into the nozzle. The inner diameter is maintained at 4 to 12 times the fuel injection hole diameter to create appropriate flow characteristics
2Loss of energy
If fuel injection holes are positioned close to the exit end to reduce mixing length, then pressure loss is reduced, but flame holding and flashback become more likely
Solution Approach 1:
The recession distance is defined as a multiple of the fuel injection hole diameter (5 to 100 times), creating a scalable parameter that adapts to different nozzle designs. This parameter optimization balances the competing requirements of minimal pressure loss and sufficient flashback prevention for various fuel types and operating conditions
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 high gas turbine efficiency with low NOx emissions and durability by preventing flashback into the mixing tubes, allowing for effective combustion of high-hydrogen or syngas fuels without significant risk of flame holding or damage.
Implementation Method 1
Due to the high turbulent flame velocity and wide flammability range, premixed hydrogen fuel combustion nozzle design is challenged
Implementation Method 2
Diffusion hydrogen fuel combustion using direct fuel injection methods inherently generates high NOx
Implementation Method 3
A fuel/air mixing tube for use in a fuel/ air mixing tube bundle
Implementation Method 4
oxides of nitrogen, carbon monoxide, and unburned hydrocarbons. It is well known in the art that oxidation of molecular nitrogen in air breathing engines
Implementation Method 5
high temperature, high pressure combustion product or gas stream. Thereafter, combustor assembly 14 channels the combustion gas stream to turbine 30 which coverts thermal energy to mechanical
Data Source
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AI summary
A fuel/air mixing tube (130) for use in a fuel/air mixing tube bundle (121) is provided. The fuel/air mixing tube (130) includes an outer tube wall (201) extending axially along a tube axis between an inlet end (134) and an exit end (135), the outer tube wall (201) having a thickness extending between an inner tube surface (203) having a inner diameter and an outer tube surface (202) having an outer tube diameter. The tube (130) further includes at least one fuel injection hole having a fuel injection hole (142) diameter extending through the outer tube wall (201), the fuel injection hole (142) having an injection angle relative to the tube axis. The invention provides good fuel air mixing with low combustion generated NOx and low flow pressure loss translating to a high gas turbine efficiency, that is durable, and resistant to flame holding and flash back.