Gas Turbine Combustor Primary Zone Control for Emissions Stability
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Solution Overview
Problem
Gas turbine engines face varying emissions of NOx, CO, and UHC due to changes in compressor inlet conditions, as the primary zone temperature in the combustor fluctuates with compressor inlet temperature, pressure, and fuel-air ratio, leading to inconsistent pollutant formation.
Innovation Solution
A method and system that control the primary zone control parameter in the combustor to maintain a constant value over a range of compressor inlet air temperatures, determining the turbine entry temperature based on a predetermined relationship, and adjusting engine operating parameters to ensure consistent emissions by using a controller and sensors to manage compressor intake air flow, delivery air pressure, fuel flow, and air-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a flat (constant) Turbine Entry Temperature (TET) rating line is used over the range of compressor inlet temperature conditions, then the Turbine Entry Temperature remains constant, but the primary zone temperature varies with compressor inlet conditions leading to varying emissions
Solution Approach 1:
The invention changes the control parameter from constant TET to constant primary zone temperature (Tpz). By controlling Tpz to remain substantially constant across varying compressor inlet temperatures, the combustion conditions are stabilized, which directly reduces the variation in emissions. This is achieved by adjusting fuel flow rate and air-fuel ratio based on sensed T1 conditions.
Solution Approach 2:
The system uses feedback control by sensing the compressor inlet temperature (T1) and using this information to adjust the fuel flow rate and air-fuel ratio. This closed-loop control ensures that the primary zone temperature remains constant despite changes in ambient conditions, thereby stabilizing emissions.
2Ease of operation
If primary zone temperature is allowed to vary with compressor inlet conditions, then the system operates simply, but emissions of NOx, CO, and UHC vary consistently
Solution Approach 1:
The invention introduces active control of the primary zone temperature parameter, changing it from a passive variable to an actively maintained constant. This is done by adjusting fuel flow and air-fuel ratio based on sensed inlet temperature conditions, thereby achieving consistent emissions while maintaining operational simplicity through automated control.
3Object-generated harmful factors
If fuel flow rate and air-fuel ratio are adjusted to maintain constant primary zone temperature, then emissions are stabilized, but the control system complexity increases
Solution Approach 1:
The control system uses feedback from temperature sensors to automatically adjust fuel flow rate and air-fuel ratio. This closed-loop control stabilizes primary zone temperature and emissions without requiring complex manual intervention. The system continuously senses T1, compares it to target conditions, and adjusts parameters accordingly.
Solution Approach 2:
The system performs self-regulation by using its own sensed temperature data to automatically adjust its operating parameters. The control system serves itself by using feedback to maintain optimal combustion conditions without external intervention, thereby stabilizing emissions through automated means.
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 stabilizes emissions of NOx, CO, and UHC across varying compressor inlet conditions, optimizing their control and reducing the risk of exceeding prescribed limits, especially at temperature extremes, thereby enhancing environmental and operational efficiency.
Implementation Method 1
a combustor for burning fuel with at least some of the compressed air
Implementation Method 2
a turbine for extracting energy from the resultant accelerated combustion product
Implementation Method 3
a compressor for compression of air
Data Source
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AI summary
A method of controlling a combustion system of a gas turbine engine (10). The gas turbine engine (10) has a combustor (28) with a primary combustion zone (110), of which a condition in the primary combustion zone (110) is defined by a primary zone control parameter. The method comprises controlling the primary zone control parameter (PZCP) to be substantially constant value over a range of values of compressor inlet air temperature (T1).