Transition Duct Late Injection for Turbomachine Efficiency
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Solution Overview
Problem
Turbomachines face challenges in achieving efficient energy extraction and reducing NOx production due to high combustion gas temperatures, which promote flashback and increase nitrogen oxide formation, while lower temperatures lead to increased carbon monoxide and unburned hydrocarbons, especially when using ducts that shift hot gas flow.
Innovation Solution
The implementation of transition ducts with late injection features, which eliminate the need for first stage nozzles by utilizing tangential and radial components of the flow, and incorporate late injection assemblies to increase combustion gas temperatures without boosting NOx production, thereby enhancing thermodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If higher combustion gas temperatures are used, then thermodynamic efficiency is improved, but NOx production increases and flashback risk increases
Solution Approach 1:
Fuel is injected and combusted in the transition duct before the hot gas enters the combustor section, pre-heating the combustion gases and establishing a controlled burn pattern that prevents flashback while enabling higher downstream temperatures without proportional NOx increases
Solution Approach 2:
The combustion process is divided into two stages: initial combustion in the transition duct using injected fuel, and secondary combustion in the combustor section. This segmentation allows temperature control in different zones, achieving high efficiency while managing NOx formation in the main combustor
2Use of energy by moving object
If higher combustion gas temperatures are used, then thermodynamic efficiency is improved, but flashback risk increases
Solution Approach 1:
Fuel injection and combustion occur in the transition duct before the main combustor, creating a controlled flame pattern that stabilizes the flow and prevents flashback into the fuel supply system while enabling higher operating temperatures
Solution Approach 2:
The transition duct acts as an intermediary zone between the fuel injection system and the main combustor, providing a controlled environment for initial combustion that mediates between fuel supply and high-temperature operation, preventing direct flashback exposure
3Object-generated harmful factors
If lower combustion gas temperatures are used, then NOx production is reduced, but chemical reaction rates decrease, increasing carbon monoxide and unburned hydrocarbons
Solution Approach 1:
Combustion is segmented into an initial stage in the transition duct and a main stage in the combustor section, allowing complete combustion to occur in controlled zones at lower temperatures, reducing unburned hydrocarbons while maintaining low NOx production
Solution Approach 2:
The combustion process continues continuously from the transition duct through the combustor section, ensuring complete fuel consumption and minimizing unburned hydrocarbons and carbon monoxide even at lower operating temperatures
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 solution increases the efficiency and power output of turbomachines by eliminating pressure drops and first stage nozzles, while minimizing NOx production and improving combustion efficiency through targeted fuel injection downstream of initial combustion.
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
incorporate late injection assemblies to increase combustion gas temperatures without boosting NOx production
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 of the plurality of transition ducts 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 of the plurality of transition ducts 50 is offset from the inlet 52 along the longitudinal axis 90 and the tangential axis 92. The turbomachine 10 includes a support ring assembly downstream of the plurality of transition ducts 50 along a hot gas path 104, and a plurality of mechanical fasteners 200 connecting at least one transition duct 50 of the plurality of transition ducts 50 to the support ring assembly. The turbomachine 10 includes a late injection assembly 210 providing fluid communication for an injection fluid to flow into the interior 57 downstream of the inlet 52 of at least one transition duct 50 of the plurality of transition ducts 50.