Gas Turbine Fuel Flow Control for Combustion Dynamics
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Solution Overview
Problem
Gas turbine engines face issues with combustion dynamics and emissions due to varying pressure oscillations, leading to premature wear of hardware components, which existing technologies have not effectively addressed.
Innovation Solution
A system and method for controlling a gas turbine engine by measuring compressor inlet temperature and calculating turbine reference temperature to adjust fuel flow using a look-up table or baseline fuel schedule with a bias parameter, thereby minimizing combustion dynamics and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel flow is reduced to minimize NOx emissions, then emissions are improved, but combustion dynamics worsen causing pressure oscillations and hardware wear
Solution Approach 1:
The fuel flow control system dynamically adjusts fuel distribution across multiple circuits based on real-time operating conditions (compressor inlet temperature, turbine reference temperature). The system transitions from static fuel scheduling to dynamic control, modifying fuel splits between lean and rich circuits as engine conditions change, thereby simultaneously controlling emissions and preventing combustion dynamics issues
Solution Approach 2:
The system changes the parameter of fuel flow distribution by using temperature-dependent lookup tables to determine optimal fuel splits. By monitoring compressor inlet temperature and turbine reference temperature, the system selects appropriate fuel circuit configurations from pre-calculated tables, adjusting fuel parameters to maintain stable combustion while minimizing emissions across different operating ranges
2Object-generated harmful factors
If multiple fuel circuits are used to control emissions, then emissions are improved, but device complexity increases
Solution Approach 1:
The fuel delivery system is segmented into multiple independent fuel circuits (PM1, PM2, PM3, quaternary), each with its own control valve and fuel nozzles. This segmentation allows independent control of fuel flow to different combustor regions, enabling precise control of combustion chemistry to minimize NOx emissions while maintaining stable combustion through coordinated operation of the segmented circuits
Solution Approach 2:
The multiple fuel circuits serve multiple functions: they control NOx emissions through staged combustion, prevent combustion dynamics by maintaining appropriate fuel-air ratios, and adapt to different operating conditions. The same fuel circuit infrastructure handles both emissions control and combustion stability requirements, making the system multi-functional despite the apparent complexity
3Reliability
If fuel flow is increased to stabilize combustion, then combustion dynamics are improved, but NOx emissions worsen
Solution Approach 1:
Different fuel circuits provide different local combustion qualities within the combustor. Lean fuel circuits (PM1, PM2) provide stable combustion with lower local temperatures to reduce NOx, while rich fuel circuits (PM3, quaternary) provide additional fuel when needed for stability. Each circuit is positioned at specific locations in the combustor to create localized combustion zones with optimized fuel-air ratios, achieving both stability and low emissions through spatial distribution of combustion quality
Data Source
AI summary
Embodiments for controlling a gas turbine engine to minimize combustion dynamics and emissions are disclosed. Methods and an apparatus are provided for controlling the gas turbine engine where a compressor inlet temperature is measured and a turbine reference temperature is calculated in real-time and utilized to determine the most-efficient fuel splits and operating conditions for each of the fuel circuits. The fuel flow for the fuel circuits are then adjusted according to the identified fuel split.