Gas Turbine Pilot Fuel Flow Tuning for Emissions and Stability
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Solution Overview
Problem
Gas turbine combustors face challenges in achieving low pollutant emissions while maintaining dynamic stability, particularly due to the complex interaction between fuel stages in two-stage pilots, which requires time-consuming and computationally intensive tuning to balance emissions and stability across varying conditions.
Innovation Solution
A method is introduced where the stage with a faster dynamic response is initially set to achieve a desired operating condition, followed by adjusting the second stage to maintain stability and reduce pollutant emissions, utilizing a controller to manage fuel flows through separate valves for each stage based on input signals from emission and dynamics sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a two-stage pilot is used to reduce pollutant emissions, then emissions are reduced, but the system becomes more complex and difficult to tune
Solution Approach 1:
The pilot fuel supply system is divided into two independently controllable stages: a first stage and a second stage. Each stage can be controlled separately through dedicated fuel supply valves, allowing independent optimization of emissions and stability characteristics. This segmentation enables the system to achieve low emissions while maintaining manageable complexity through modular control.
Solution Approach 2:
The system employs dynamic control of fuel flows to both stages based on real-time operating conditions. The controller adjusts fuel flow rates responsively to changing conditions such as load variations, ambient temperature, and combustion stability requirements. This dynamic adaptation allows the system to maintain optimal emissions and stability across varying operating ranges without requiring complex static tuning.
2Reliability
If manual tuning is performed during start-up, then initial emissions criteria are satisfied, but extended operation requires re-tuning due to variable conditions
Solution Approach 1:
The system incorporates sensors that continuously monitor combustion conditions and provide feedback to the controller. This feedback mechanism enables automatic adjustment of fuel flows to both stages in response to changing operating conditions such as ambient temperature, humidity, and load variations. The feedback-driven control maintains emissions compliance without requiring manual re-tuning during extended operation.
Solution Approach 2:
The controller dynamically changes operating parameters including fuel flow rates, air-to-fuel ratios, and stage-specific control variables in response to detected condition changes. By continuously adapting these parameters, the system maintains optimal combustion characteristics and emissions performance across varying operating conditions without manual intervention.
3Object-generated harmful factors
If fuel flow is adjusted to reduce emissions, then pollutant levels decrease, but dynamic stability may be compromised
Solution Approach 1:
By segmenting the fuel supply into two independently controllable stages, the system can selectively adjust fuel flow to each stage based on the specific operational requirement. When emissions reduction is prioritized, fuel flow to the second stage can be reduced while maintaining stable combustion in the first stage. This segmentation enables decoupled optimization of emissions and stability.
Solution Approach 2:
The system employs dynamic control strategies that adjust fuel flows to both stages based on real-time combustion stability monitoring. The controller can rapidly respond to stability concerns by adjusting fuel delivery, ensuring that emissions reduction measures do not compromise dynamic stability. This dynamic adaptation allows the system to maintain both low emissions and stable combustion across varying conditions.
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 quicker and more efficient tuning of fuel stages, maintaining stability while achieving desired emissions levels, even under changing conditions, by allowing for precise control of fuel fractions and dynamic adjustments to prevent instability.
Implementation Method 1
A staged gas turbine combustor pilot is described in United States patent 6,877,307 as having a premix stage wherein air and fuel are premixed prior to being combusted in a pilot combustion region
Implementation Method 2
a combustor for producing a hot gas by burning fuel in the presence of the compressed air produced by the compressor
Data Source
Figure 1~2
AI summary
A method and system for controlling combustion in a gas turbine combustor (18) includes adjusting an amount of a premix fuel portion (30) of a pilot fuel (28) provided to a premix burner stage (48) of a pilot (46) of the gas turbine combustor. The amount of the premix fuel portion is adjusted from a preset premix fuel portion amount to an adjusted premix fuel portion amount to achieve a desired first operating condition of the combustor. An amount of a diffusion fuel portion(34) of the pilot fuel provided to a diffusion burner stage (50) of the pilot is then-adjusted from a preset diffusion fuel portion amount to an adjusted diffusion fuel portion amount to achieve a desired second operating condition of the combustor.