Gas Turbine Partial Load Efficiency via Three-Degree Control
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Solution Overview
Problem
Gas turbine engines exhibit low efficiency and high emissions during part-load operations, particularly NOx emissions, due to the challenges in controlling airflow and thermal distortions in existing control methods.
Innovation Solution
Implementing a method that controls a gas turbine engine with three degrees of freedom: modifying the bleed flow rate of the compressor upstream of the discharge, adjusting the number of operating burners through annular combustor staging, and regulating the nozzle guide vanes to control the enthalpy drop between high and low pressure turbines, thereby optimizing air mass flow rate and flame temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If compressor bleed control is used to manage part load operation, then airflow control is achieved, but work loss increases due to dissipating compressed air
Solution Approach 1:
The combustion system is segmented into multiple independently controllable burners arranged in stages. This allows selective activation of burners based on load requirements, enabling precise control of the combustion process and airflow distribution without wasting compressed air through bleed valves.
Solution Approach 2:
The invention changes the control parameter from bleed flow rate to burner staging configuration. By adjusting which burners are active and their individual fuel/air ratios, the system achieves airflow control while maintaining energy efficiency, avoiding the work loss inherent in traditional bleed control methods.
2Object-generated harmful factors
If combustor staging is used to control part load operation, then emissions are reduced, but thermal distortions occur on hot gas path components
Solution Approach 1:
Different burners are configured with different local characteristics including varying fuel/air ratios and combustion intensities. This local quality differentiation allows the system to achieve low emissions in active burners while distributing thermal loads across multiple burners, preventing excessive thermal distortions on hot gas path components.
Solution Approach 2:
The combustor staging system dynamically adjusts which burners are active and their individual operating parameters based on real-time load conditions. This dynamic control enables the system to maintain optimal temperature distribution and minimize thermal distortions while achieving low emissions across varying operating conditions.
3Ease of operation
If traditional two-degree-of-freedom control is used, then part load operation is manageable, but efficiency remains low
Solution Approach 1:
The invention adds a third degree of freedom to the control system by introducing nozzle guide vane (NGV) positioning control. This additional dimension allows independent adjustment of the air mass flow rate through the turbine, enabling the system to optimize efficiency across the entire operating range while maintaining ease of part load operation through coordinated control of all three parameters.
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 partial load efficiency and reduces emissions by allowing for more precise control of gas turbine parameters, limiting work loss and thermal distortions, and achieving high efficiency across varying load ranges.
Implementation Method 1
a bleed that extracts a fraction of the flow rate of fluid of the compressor at a compressor stage more upstream of the discharge, to limit the loss of work
Implementation Method 2
a nozzle guide vane (NGV) control, in which the change in enthalpy drop between the high and low pressure turbine is modified, allowing for air mass flow rate regulation
Implementation Method 3
burners, an high pressure turbine and a low pressure turbine
Data Source
AI summary
A method for improving partial load efficiency in a gas turbine engine including a compressor, burners, a high pressure turbine and a low pressure turbine; including the step of operating the gas turbine engine by regulating at least: air mass flow rate and flame temperature; regulation is carried out by controlling at least: the air mass flow rate supplied to the combustion chamber from the compressor, and the number of operating burners, and the change in enthalpy drop between the high and low pressure turbine to control the air mass flow rate.