Combustor Flow Conditioner Radial Swirl Fuel Mixing
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Solution Overview
Problem
Gas turbine combustors face challenges in achieving uniform fuel mixture distribution, leading to increased NOx emissions and thermal stresses due to high combustion temperatures, which are not adequately addressed by existing dual-fuel nozzle designs.
Innovation Solution
A combustor design featuring a tube bundle with a flow conditioner and an annular insert that imparts radial swirl to the working fluid and fuel, enhancing mixing efficiency and reducing the likelihood of flame holding or flashback, while allowing for a more thorough pre-mixing of gaseous and liquid fuels with the working fluid before combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a rich fuel/air mixture is provided in the combustion zone to increase combustion gas temperature, then thermodynamic efficiency improves, but nitrogen oxide emissions significantly increase
Solution Approach 1:
The combustor divides the combustion process into multiple zones with different air-fuel ratios. The combustion chamber receives a lean fuel/air mixture (lower emissions) while a separate post-combustion chamber adds fuel to maintain temperature (efficiency). This segmentation allows independent control of emissions and temperature, resolving the contradiction between improving thermodynamic efficiency and reducing nitrogen oxide emissions.
2Object-generated harmful factors
If a lean fuel/air mixture is provided to reduce nitrogen oxide emissions, then emissions decrease, but combustion temperature decreases reducing thermodynamic efficiency
Solution Approach 1:
The system performs preliminary combustion in the combustion chamber with a lean fuel/air mixture, establishing a controlled burn that reduces nitrogen oxide emissions. Then, additional fuel is introduced in the post-combustion chamber to restore and maintain the required combustion temperature for thermodynamic efficiency. This preliminary action sequence allows emissions control followed by temperature restoration.
3Quantity of substance
If existing dual-fuel nozzle designs are used for premixing fuel and air, then fuel injection is achieved, but uniformity of the fuel mixture is insufficient leading to increased NOx emissions and thermal stresses
Solution Approach 1:
The fuel injection system is segmented into multiple injection points and pathways. Liquid fuel is injected through atomizers in the combustion chamber, while gaseous fuel is injected through ports in the post-combustion chamber. This segmentation of fuel delivery allows precise control over fuel distribution and mixing, achieving the uniformity required to reduce NOx emissions and thermal stresses while maintaining adequate fuel injection quantities.
Solution Approach 2:
Different regions of the combustor receive different fuel types and injection characteristics. The combustion chamber receives liquid fuel through atomizers designed for fine dispersion, while the post-combustion chamber receives gaseous fuel through ports designed for even distribution. This local quality differentiation in fuel injection ensures optimal mixing uniformity in each zone, resolving the contradiction between achieving sufficient fuel injection and ensuring uniform mixture distribution.
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 improves the uniformity of the fuel mixture, reduces NOx emissions, and enhances combustion stability, allowing for a greater range of operability with less reactive fuels and minimizing the need for additives like water, while also reducing the weight and cost of the combustor.
Implementation Method 1
a flow conditioner that imparts radial swirl to the working fluid to enhance mixing of the working fluid and the fuel
Implementation Method 2
The tubes generally allow a gaseous and/or liquid fuel and a working fluid to thoroughly mix before entering a combustion chamber
Implementation Method 3
the fuel and the working fluid are mixed within the tube and the mixed fuel-working fluid mixture flows through the tube into the combustion zone
Data Source
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AI summary
A combustor includes a plurality of tubes (20) arranged in a tube bundle (22) and supported by at least one plate (24) that extends radially within the combustor, wherein each tube (20) includes an upstream end (34) axially separated from a downstream end and provides fluid communication through the tube bundle (22). A flow conditioner (18) extends upstream from the upstream end (34) of one or more of the plurality of tubes (20), and a radial passage (40) extends through the flow conditioner (18). A method for distributing fuel in a combustor including flowing a working fluid (16) through a flow conditioner (18) that extends from a tube (20) that is configured in a tube bundle (22) comprising a plurality of tubes (20) and that is supported by at least one plate (24). The flow conditioner (18) includes at least one radial passage (40) to impart radial swirl to the working fluid (16). Flowing a fuel through an annular insert (50) that is at least partially surrounded by the flow conditioner (18).