Gas Turbine Combustor Pilot Fuel Split for Transient Stability
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Solution Overview
Problem
Existing methods for controlling combustion in gas turbine engines fail to adequately address combustion instability and emissions during transient conditions, leading to increased harmful emissions, temperature fluctuations, and structural integrity issues.
Innovation Solution
A method that dynamically adjusts the pilot fuel split during transient conditions by using a look-up table to generate a transient split offset, which is applied to the pilot fuel split based on engine conditions, maintaining total fuel quantity and reducing the pilot fuel split gradually to stabilize combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pilot fuel split is conventionally scheduled dependent on engine load, then the combustion system operates efficiently at steady state, but combustion instability occurs during transient conditions leading to increased emissions and temperature fluctuations
Solution Approach 1:
The patent implements dynamic adjustment of the pilot fuel split by applying a transient split offset that varies with engine load changes. Unlike conventional static scheduling, the offset is calculated based on the difference between current and previous load values, enabling the system to adapt pilot fuel delivery in real-time during transient conditions. This dynamic approach maintains combustion stability while minimizing emissions across varying operating conditions.
Solution Approach 2:
The control system uses feedback from load monitoring to adjust the pilot fuel split. The Engine Control Unit continuously monitors engine load and calculates the transient split offset based on load changes, creating a closed-loop control mechanism. This feedback-driven approach allows the system to respond to transient conditions and correct combustion instability before it leads to harmful emissions.
2Reliability
If the pilot fuel split is increased to stabilize combustion during transients, then combustion stability improves, but emissions increase due to richer burning
Solution Approach 1:
The patent changes the parameter of pilot fuel split dynamically by introducing a transient split offset that is applied to the scheduled pilot fuel split. The offset is calculated based on engine load changes and is adjusted continuously during transient conditions. This parameter change allows the system to maintain combustion stability with minimal increase in emissions by optimizing the pilot-to-main fuel ratio in real-time rather than using a fixed rich mixture.
3Reliability
If the pilot fuel split is rapidly adjusted during transient conditions, then combustion stability is quickly restored, but pressure fluctuations increase causing structural stress
Solution Approach 1:
The system dynamically adjusts the pilot fuel split with controlled responsiveness to load changes. The transient split offset is calculated based on the magnitude of load change, allowing rapid adjustment when needed while smoothing adjustments during smaller transients. This dynamic control strategy restores combustion stability quickly while minimizing pressure fluctuations and associated structural stress.
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
Reduces combustion instability and flame failure during transient load changes, maintaining stable combustion and minimizing emissions, thereby enhancing engine reliability and reducing emissions during recovery from transient events.
Implementation Method 1
The pilot flame has a lower air to fuel ratio and burns in a richer flame. The pilot flame is more stable than the main flame and helps to stabilise the main flame.
Implementation Method 2
The main flame has a relatively high air to fuel ratio and is a lean burn flame giving good efficiency and low emissions.
Data Source
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AI summary
A method of controlling a combustor of a gas turbine engine is disclosed. The method comprising the steps supplying a total fuel quantity to the combustor dependent on a load of the gas turbine engine, the total fuel quantity is split into a pilot fuel quantity and a main fuel quantity via a pilot fuel split, monitoring at least one signal of at least one condition of the gas turbine engine, generating a steady state value of the at least one signal indicative of a steady state of the gas turbine engine, detecting a change in the at least one signal from the steady-state value. When the change in the at least one signal from the steady state value exceeds a predetermined limit, the method applies the steps generating a transient split offset for the pilot fuel split from a look-up table and applying the transient split offset to the pilot fuel split while maintaining the total fuel quantity being supplied at any point in time.