Variable Backflow Margin Control for Gas Turbine Cavity Pressures
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Solution Overview
Problem
Conventional gas turbine systems face performance losses due to inefficient cooling and purge air flow management, where the constant BFM pressure ratio fails to account for variations over the life cycle of components, leading to suboptimal operation and potential hot gas ingestion.
Innovation Solution
A method and system that dynamically adjust the BFM pressure ratio based on fired hours and starts, using a scalar to modify the pressure ratio and control bleed air flow to maintain optimal cavity pressures, thereby ensuring efficient cooling and preventing hot gas ingestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant BFM pressure ratio is used to control cooling air flow, then the system operation is simple, but the performance is suboptimal because it does not account for variations over component life cycle
Solution Approach 1:
The patent applies dynamics by transitioning from a constant BFM pressure ratio to a variable pressure ratio that changes over time based on component life cycle. The system dynamically adjusts the pressure ratio using a scalar value that increases with fired hours and starts, allowing optimal performance at different stages of component life while maintaining manageable control complexity through automated adjustments.
2Reliability
If more cooling air is extracted from the compressor to maintain adequate BFM, then component reliability is improved, but compressor efficiency decreases due to increased work investment
Solution Approach 1:
The patent applies parameter changes by modifying the BFM pressure ratio parameter over time based on component aging. The scalar value, which increases with fired hours and starts, adjusts the pressure ratio to match the actual BFM requirements at different life stages. This ensures sufficient cooling air for reliability when needed while minimizing unnecessary air extraction and associated compressor work during early life stages.
3Reliability
If the BFM pressure ratio is increased to prevent hot gas ingestion, then component safety is improved, but cooling effectiveness may be compromised
Solution Approach 1:
The patent applies feedback by using the scalar value, which is based on monitored parameters such as fired hours and starts, to dynamically adjust the BFM pressure ratio. This feedback mechanism ensures that the pressure ratio is optimized based on actual component conditions and aging, maintaining adequate BFM for hot gas prevention while avoiding excessive pressure ratios that would compromise cooling effectiveness.
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 gas turbine performance by adapting to the life cycle conditions of components, improving efficiency and reliability, and reducing the risk of hot gas ingestion, leading to better operational performance and extended component lifespan.
Implementation Method 1
A cooling fluid such as air is provided to the turbine vanes, blades, and shrouds to maintain the temperatures of those components at appropriate levels
Implementation Method 2
The axial location or stage where the air is bled from the compressor is determined by the pressure required by the component or system to be serviced by that air
Implementation Method 3
the air used for cooling turbine components typically discharges from orifices or gaps in those components. That cooling air mixes with the combustion gases in the turbine
Data Source
AI summary
A system and method for controlling the performance of a gas turbine system is provided. A backflow margin pressure ratio for a component is determined. A modified backflow margin pressure ratio for the component is calculated based on the number of fired hours and starts. Bleed air along a first flow path is controlled based on the modified backflow margin pressure ratio.