Transition Duct Late Injection Combustion Efficiency
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Solution Overview
Problem
Turbomachines face challenges with high combustion gas temperatures leading to flashback, flame holding, and increased NOX production, while lower temperatures result in carbon monoxide and unburned hydrocarbon production, and existing late injection assemblies weaken the transition ducts due to multiple passages.
Innovation Solution
The use of transition ducts with late injection features, including annular arrays and impingement sleeves, that eliminate the need for first stage nozzles by shifting the hot gas flow radially and tangentially, and incorporate a late injection assembly with a ring-shaped structure for improved combustion and structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple passages are added to the transition duct wall for late injection, then combustion efficiency is improved, but structural strength and component lifetime are reduced
Solution Approach 1:
The patent integrates the late injection assembly with the transition duct by forming the injection passages directly within the transition duct structure itself, merging two previously separate components. This eliminates the need for separate injection assemblies that would require additional passages through the duct wall, thereby maintaining structural strength while enabling late injection functionality for improved combustion efficiency
Solution Approach 2:
The transition duct is designed to serve multiple functions: it acts as both the flow passage structure and the late injection assembly housing. The transition duct incorporates fuel injection passages, air mixing passages, and ignition features within its structure, allowing a single component to perform multiple functions that previously required separate assemblies, thus avoiding strength reduction while achieving improved combustion
2Productivity
If combustion gas temperature is increased to improve thermodynamic efficiency, then efficiency improves, but flashback and flame holding occur causing fuel nozzle damage
Solution Approach 1:
The patent introduces late injection of fuel and air further downstream in the combustion chamber where the flow conditions are more favorable. This preliminary positioning of the injection point ensures that fuel is introduced at a location where flashback and flame holding are minimized, allowing high combustion gas temperatures to be maintained without damaging the fuel nozzles
Solution Approach 2:
The transition duct with its integrated late injection assembly acts as an intermediary structure that enables controlled fuel injection downstream. This intermediary mechanism allows the system to achieve high thermodynamic efficiency through elevated combustion temperatures while preventing direct exposure of fuel nozzles to harmful flashback and flame holding conditions
3Shape
If first stage nozzles are used to shift hot gas flow, then flow shifting is achieved, but pressure drops increase reducing efficiency
Solution Approach 1:
The patent removes the first stage nozzles from the system and replaces them with a transition duct that has integrated flow shifting capabilities. By extracting the separate nozzle component and integrating its function into the transition duct structure, the design eliminates the pressure drops associated with traditional first stage nozzles while still achieving the necessary flow direction control
Solution Approach 2:
The transition duct is designed to combine multiple functions: it serves as the structural passage, the flow shifting mechanism, and the late injection assembly housing. By merging the flow direction control function into the transition duct itself rather than using separate first stage nozzles, the design achieves flow shifting without the associated pressure losses
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 enhances the efficiency and power output of turbomachines by eliminating first stage nozzles, reducing pressure drops, and improving combustion efficiency while maintaining structural integrity through the use of ceramic materials and floating interfaces.
Implementation Method 1
ducts for combustor sections have been introduced that, while flowing the hot gas longitudinally therethrough, additionally shift the flow radially and/or tangentially such that the flow has various angular components
Implementation Method 2
Each tube comprises a radially directed air inlet through which a portion of the compressed main air flows into the tube and mixes with fuel to produce an injection fluid
Implementation Method 3
The air is then flowed from the compressor section to the combustor section, where it is mixed with fuel and combusted, generating a hot gas flow
Implementation Method 4
The hot gas flow is provided to the turbine section, which utilizes the hot gas flow by extracting energy from it to power the compressor, an electrical generator, and other various loads
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A turbomachine 10 includes a plurality of transition ducts 50 disposed in a generally annular array. Each transition duct 50 includes an inlet 52, an outlet 54, and a passage 56 defining an interior 57 and extending between the inlet 52 and the outlet 54 and defining a longitudinal axis 90, a radial axis 94, and a tangential axis 92. The outlet 54 of each transition duct 50 is offset from the inlet 52 along the longitudinal axis 90 and the tangential axis 92. Each transition duct 50 further includes an upstream portion 170 and a downstream portion 172. The turbomachine 10 further includes a late injection assembly 250 disposed between the upstream portion 170 and the downstream portion 172 of a transition duct 50 and which provides fluid communication for an injection fluid to flow into the interior 57 downstream of the inlet 52 of the transition duct 50. The late injection assembly 250 includes a late injection ring 252.