Diffusion Fuel Nozzle with Exhaust Gas Recirculation
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Solution Overview
Problem
Gas turbine engines face challenges in controlling premix flames, leading to instability and increased exhaust emissions, and they consume large amounts of air with significant exhaust gas wastage, which is not efficiently utilized.
Innovation Solution
A system employing diffusion combustion with separate injection of fuel and oxidant streams into a turbine combustor, utilizing exhaust gas recirculation to create a diffusion flame, allowing for independent control of fuel, oxidant, and diluent flows to achieve stoichiometric combustion and reduce emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If premix combustion is used in gas turbine engines, then combustion efficiency is improved, but flame stability deteriorates and exhaust emissions increase
Solution Approach 1:
The fuel injection system is segmented into multiple separate fuel nozzles that inject fuel at different locations and angles into the combustor. This segmentation allows the fuel to mix with exhaust gas in a controlled manner, creating stable diffusion flames while maintaining combustion efficiency. The separate nozzle arrangement prevents premature mixing and flame instability associated with conventional premix systems.
Solution Approach 2:
Exhaust gas is introduced as an intermediary substance between the fuel and primary oxidant (air). This exhaust gas acts as a diluent that moderates the combustion process, providing thermal inertia that stabilizes the flame while reducing peak temperatures that lead to NOx emissions. The exhaust gas recirculation system serves as the intermediary mechanism.
2Power
If large amounts of air are consumed as oxidant, then combustion power is improved, but exhaust gas wastage increases
Solution Approach 1:
Instead of discarding exhaust gas to the atmosphere, the system recovers and recirculates it back to the combustor. The exhaust gas is recovered from the turbine outlet and redirected through recirculation piping to mix with fuel at the fuel nozzles, where it serves as a diluent and thermal buffer. This recovery process eliminates wastage and improves overall system efficiency.
Solution Approach 2:
The exhaust gas serves multiple functions simultaneously: it acts as a diluent to control combustion temperature, provides thermal inertia for flame stability, reduces NOx emissions, and is recycled to improve overall system efficiency. This multi-functionality maximizes the utility of the exhaust stream rather than treating it as waste.
3Object-generated harmful factors
If exhaust gas recirculation is increased, then emissions are reduced, but combustion temperature control becomes more difficult
Solution Approach 1:
The system incorporates feedback control mechanisms where exhaust gas recirculation rates are adjusted based on measured combustion parameters and emissions levels. Sensors monitor flame stability and temperature, and the control system modulates the recirculation flow to maintain optimal combustion conditions. This feedback loop makes high levels of exhaust recirculation easier to control.
Solution Approach 2:
The exhaust gas recirculation system is designed to be dynamically adjustable, allowing the recirculation ratio to be varied in response to changing operating conditions. The fuel nozzle design and recirculation piping enable rapid adjustment of exhaust gas flow rates to maintain stable combustion across different load conditions, making high recirculation levels operationally manageable.
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 enhances flame stability, increases CO2 production, and allows for greater exhaust gas recirculation, reducing emissions and improving energy recovery by using the exhaust gas as a diluent to control temperature and emissions.
Implementation Method 1
a first diffusion fuel nozzle, wherein the first diffusion fuel nozzle has first and second passages that separately inject respective first and second flows into a chamber of the turbine combustor to produce a diffusion flame
Implementation Method 2
an exhaust gas compressor, wherein the exhaust gas compressor is configured to compress and route an exhaust gas from the turbine to the turbine combustor along an exhaust recirculation path
Implementation Method 3
a turbine driven by combustion products from the diffusion flame in the turbine combustor
Data Source
AI summary
A system is provided with a turbine combustor having a first diffusion fuel nozzle, wherein the first diffusion fuel nozzle has first and second passages that separately inject respective first and second flows into a chamber of the turbine combustor to produce a diffusion flame. The first flow includes a first fuel and a first diluent, and the second flow includes a first oxidant. The system includes a turbine driven by combustion products from the diffusion flame in the turbine combustor. The system also includes an exhaust gas compressor, wherein the exhaust gas compressor is configured to compress and route an exhaust gas from the turbine to the turbine combustor along an exhaust recirculation path.