Variable Compressor Extraction for Turbine Turn Down
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Solution Overview
Problem
Combustion turbine engines face challenges in maintaining high combustor exit temperatures during load reduction, leading to increased carbon-monoxide (CO) and unburned hydrocarbon (UHC) emissions, which are prohibited by regulatory agencies.
Innovation Solution
The implementation of variable compressor extraction flows using variable orifices controlled by operating characteristics, allowing for bypassing of compressor air around the primary combustion zone and reintroduction of extraction air to maintain suitable fuel/air ratios and reduce emissions during load rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the turbine load decreases, then the power output is reduced, but the combustor exit temperature drops below the lower limit causing increased CO and UHC emissions
Solution Approach 1:
The patent implements variable compressor air extraction that dynamically adjusts extraction flow based on turbine load conditions. During turn-down, the extraction flow is increased to maintain suitable fuel/air ratios in the combustor, preventing incomplete combustion and controlling CO/UHC emissions while allowing power output to be reduced.
Solution Approach 2:
The system changes the extraction air flow parameter from the compressor during turn-down operations. By increasing the extraction flow, the system maintains appropriate combustor conditions (fuel/air ratio) that prevent incomplete combustion, thereby controlling harmful emissions while enabling reduced power output.
2Object-generated harmful factors
If compressor air is extracted and bypassed around the combustor, then the fuel/air ratio is maintained for low emissions, but the system complexity increases with variable orifices and control mechanisms
Solution Approach 1:
The compressor extraction system serves multiple functions: it provides cooling air to the turbine, maintains combustor pressure, and controls fuel/air ratios for emissions management. By making the extraction flow variable, the single extraction system accomplishes multiple objectives across different operating conditions without requiring separate control systems.
Solution Approach 2:
The control system uses feedback from combustor exit temperature and emission levels to automatically adjust the extraction orifice positioning. The system self-regulates the extraction flow to maintain optimal combustor conditions, reducing the need for external intervention and simplifying overall system operation.
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 effectively maintains low CO and UHC emission levels and improves the turbine's turn down capability and fuel efficiency by adjusting compressor extraction flows to maintain combustor exit temperatures.
Implementation Method 1
combustion turbine engines burn a hydrocarbon-air mixture in a combustor assembly and generate a combustion gas stream
Data Source
AI summary
Systems and methods for controlling compressor (105) extraction air flows from a compressor (105) of a turbine system (100) during engine turn down are provided. In one embodiment, a method for controlling compressor (105) extraction air flows from a compressor (105) of a turbine system (100) during turn down includes a control unit (130) monitoring one or more operating parameters of a turbine system (100) associated with an exit temperature of a combustor (110) of the turbine system (100). The method further includes the control unit (130) detecting one or more operating parameters meeting or exceeding a threshold associated with a decrease in the exit temperature of the combustor (110). In response to detecting one or more operating parameter meeting or exceeding the threshold, a control signal is transmitted to at least one variable orifice (125) located in the turbine system (100) causing at least one variable orifice (125) to alter at least one extraction air flow from the compressor (105).