Staged Fuel and Air Injection for Gas Turbine Combustion
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Solution Overview
Problem
Conventional gas turbine combustion systems face limitations in achieving higher firing temperatures while maintaining low NOx emissions and efficient performance, due to the sensitivity of NOx emissions to operating temperatures and combustion characteristics, which restricts further efficiency gains.
Innovation Solution
The implementation of a staged injection system that axially injects air and fuel downstream in the combustion system, reducing reactant residence time at high temperatures and utilizing advanced fuel nozzle designs and premixing technologies to manage NOx levels, along with optimized airflow and cooling strategies to minimize pressure drops and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher operating temperatures are used to improve engine efficiency, then engine efficiency is improved, but NOx emissions increase
Solution Approach 1:
The combustion process is segmented into multiple zones with different temperature levels. A first combustion zone operates at a higher temperature to improve efficiency, while a second combustion zone operates at a lower temperature to limit NOx formation. This spatial segmentation allows the system to achieve high efficiency without excessive emissions.
Solution Approach 2:
Different regions of the combustion system are assigned different thermal characteristics. The primary combustion zone near the fuel injector operates at high temperature for efficient combustion, while downstream regions operate at lower temperatures to control NOx emissions. This local differentiation of thermal conditions resolves the contradiction between efficiency and emissions.
2Temperature
If more compressor air is directed to axially staged injectors to enable higher firing temperatures, then firing temperature is increased, but aerodynamic pressure losses increase
Solution Approach 1:
The air supply system is segmented into multiple pathways: one pathway directs air to the primary injector for high-temperature combustion, while another pathway directs air to downstream staged injectors for lower-temperature combustion. This segmentation allows efficient use of compressor air while minimizing pressure losses by matching air delivery to specific combustion zone requirements.
3Productivity
If higher firing temperatures are implemented, then engine efficiency is improved, but cooling requirements increase
Solution Approach 1:
The combustion system is segmented into high-temperature and low-temperature zones, reducing the overall volume of hot gases that require cooling. The lower operating temperature in the second combustion zone directly reduces the thermal load on cooling systems, thereby decreasing the quantity of cooling air needed while maintaining high efficiency in the primary zone.
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 allows for increased firing temperatures and improved engine efficiency while maintaining acceptable NOx emission levels, by reducing NOx formation through shorter reactant residence times and optimizing airflow and cooling, thus overcoming the limitations of conventional systems.
Implementation Method 1
reducing reactant residence time at high temperatures
Implementation Method 2
utilizing advanced fuel nozzle designs and premixing technologies to manage NOx levels
Implementation Method 3
new heat transfer technologies for cooling hot gas path components
Data Source
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AI summary
A gas turbine that includes: a combustor 13 coupled to a turbine 12 that together define a working fluid flowpath 37; a compressor discharge cavity 44; a staged injector 51; stator blade airfoils 17 extending between inboard and outboard sidewalls; and a first and second coolant flowpath. The first coolant flowpath includes: an intake section connected to the compressor discharge cavity and a downstream port formed through the inboard sidewall; an outtake section including a downstream port connected to the staged injector and an upstream port formed through the outboard sidewall; and a cooling circuit through the airfoil. The second coolant flowpath includes: an intake section connected to the compressor discharge cavity 44 and a downstream port formed through the outboard sidewall; an outtake section that comprises a downstream port connected to the staged injector and an upstream port formed through the inboard sidewall; and a cooling circuit through the airfoil.