Gas Turbine Combustor Nozzle Design for Flashback Prevention
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Solution Overview
Problem
Conventional gas turbines experience flashback issues when using high-flaming rate fuels like hydrogen, where the flame generated in the combustion chamber flows backward, potentially damaging the nozzle.
Innovation Solution
The combustor design features nozzle assemblies with a decreasing and then increasing diameter shape, combined with a swirl effect from secondary compressed air, to prevent flashback by enhancing fuel-air mixing efficiency and maintaining a low fuel-air ratio at the nozzle outlet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional nozzle structure is used, then the fuel and compressed air can be mixed and supplied into the combustion chamber, but the flame generated in the combustion chamber may flow back forwards and cause flashback in the nozzle, damaging the nozzle
Solution Approach 1:
The nozzle geometry is modified by changing the diameter profile along its length. The nozzle has a decreasing diameter section followed by an increasing diameter section, creating a specific flow velocity distribution that prevents flame backflow while maintaining proper fuel-air mixing and combustion performance.
Solution Approach 2:
The patent utilizes fluid dynamics principles by designing the nozzle with varying cross-sectional area to create a venturi-like effect. The decreasing then increasing diameter configuration manipulates pressure and velocity distributions of the fuel-air mixture, generating a flow regime that resists flashback while ensuring stable combustion.
2Productivity
If the nozzle diameter is increased to improve fuel-air mixing, then mixing efficiency may improve, but the flame backflow risk increases
Solution Approach 1:
Rather than simply increasing the overall nozzle diameter, the patent changes the diameter distribution along the nozzle length. The decreasing then increasing profile creates localized velocity increases that enhance mixing while the overall geometry maintains flow directionality that prevents flashback.
Solution Approach 2:
The nozzle employs curved transitions in its diameter profile rather than abrupt changes. The smooth curved sections allow for gradual pressure and velocity adjustments, preventing flow separation and turbulence that could lead to flashback while maintaining effective mixing.
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
This design effectively prevents flashback by increasing fluid flow rate in the nozzle decreasing section and reducing the fuel-air ratio at the nozzle outlet, ensuring efficient combustion and protecting the nozzle from flame damage.
Implementation Method 1
the nozzles has a shape with a diameter decreasing and increasing toward the rear side thereof
Implementation Method 2
combusts an air-fuel mixture to generate combustion gas
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A combustor (100) includes an outer can (110) into which fuel is introduced, an outer head (111) disposed on a front side of the outer can, an inner can (120) disposed inside of the outer can and having a combustion chamber (112) in which a fuel-air mixture is combusted, and an inner head (121) disposed to mix the fuel and the compressed air and supply the mixture into the inner can. The inner head includes a head plate (122) covering a front side of the inner can, and nozzle assemblies (123) disposed to mix the fuel and the compressed air and supply the mixture rearwards. The nozzle assembly includes a nozzle head (124) into which fuel is introduced and nozzles (130). The nozzles each is coupled between the nozzle head and the head plate to mix the fuel and the compressed air and supply the mixture rearwards. The nozzles each has a shape with a diameter decreasing and increasing toward the rear side thereof.