Combustion Injector Assembly for NOx Reduction
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Solution Overview
Problem
Existing distributed combustion systems face challenges in reducing NOx emissions due to high flame temperatures, which can be attributed to insufficient mixing of reactants with cross-flow combustion products before ignition, and inefficiencies in utilizing cooling air, as well as limitations in manufacturing complex geometries for ducting arrangements.
Innovation Solution
The implementation of injector assemblies that generate a shielding air flow to delay ignition of reactants, allowing for enhanced co-flow mixing and utilization of recaptured cooling air to form this shielding flow, combined with the use of 3D Printing/Additive Manufacturing technologies for cost-effective and precise fabrication of complex ducting arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If distributed combustion system is used to reduce NOx emissions, then NOx emissions are reduced, but flame temperature becomes too high
Solution Approach 1:
The system performs preliminary mixing of reactants with cross-flow combustion products before ignition occurs. The injector assemblies are positioned downstream to allow reactants to mix with cooler combustion products ahead of time, pre-conditioning the mixture to reduce peak flame temperature when ignition occurs.
Solution Approach 2:
Cooling air is introduced as an intermediary substance between the reactants and the hot combustion zone. This cooling air acts as a thermal buffer that absorbs excess heat and reduces flame temperature, while still allowing the combustion process to proceed effectively for NOx reduction.
2Temperature
If cooling air is used extensively to reduce flame temperature, then flame temperature is reduced, but cooling air consumption increases
Solution Approach 1:
The system recovers and reuses cooling air that would otherwise be discarded. The cooling air is introduced downstream where it can serve dual purposes: cooling the combustion zone and then being utilized as part of the combustion process itself, thereby reducing the total amount of cooling air needed from external sources.
Solution Approach 2:
The combustion system uses its own exhaust gases and internal cooling air to regulate its temperature rather than requiring extensive external cooling. The system self-regulates by utilizing its own flow resources to maintain optimal temperature levels, reducing dependence on additional cooling air supply.
3Strength
If complex ducting arrangements are manufactured using traditional methods, then structural integrity is maintained, but manufacturing cost and complexity increase
Solution Approach 1:
The patent employs additive manufacturing technology to produce the ducting arrangements, representing a fundamental change in the manufacturing parameter from traditional subtractive or formative methods. This manufacturing approach reduces cost and complexity while maintaining structural integrity through precise material deposition and controlled building processes.
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 approach reduces NOx emissions by lowering flame temperature, increases the liftoff distance of the flame, and enhances combustion efficiency while maintaining low NOx levels at high turbine inlet temperatures, and allows for stable operation with reduced cooling air consumption.
Implementation Method 1
enhanced co-flow mixing before the hot cross-flow of combustion products can ignite the flow of reactants
Implementation Method 2
This shielding effect causes an ignition delay to the flow of reactants injected into the combustion stage
Implementation Method 3
utilization of recaptured cooling air to form this shielding flow
Implementation Method 4
fuel is mixed with air and ignited to generate hot combustion products that define working gases. The working gases are directed to a turbine section where they drive the rotation of a turbine rotor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A combustion system in a combustion turbine engine is provided. The system may include a combustor wall (40) fluidly coupled to receive a cross-flow of combustion products (21). The combustor wall (40) may include a plurality of cooling air conduits (46). An injector assembly (12) may be in fluid communication with the cooling fluid conduits (46) to receive cooling fluid that passes through the cooling fluid conduits. Injector assembly (12) includes means for injecting (24, 25, 26) a flow of the cooling fluid (22) into the combustion stage. The flow of the cooling fluid may be arranged to condition interaction of a flow of reactants (19) injected to admix with the cross-flow of combustion products.