Gas Turbine Compressor Air Extraction Control via Bypass Valve
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current control systems for regulating compressor air extraction in gas turbines fail to adequately address rapid variations in desired turbine cooling air and compressor discharge pressure ratios, leading to inefficient operation and potential shutdowns due to immediate changes in pressure ratios.
Innovation Solution
A method and system that control the position of a bypass valve to adjust the flow of compressed air from a high pressure stage, bypassing an ejector, and combining it with air from a low pressure stage to maintain a desired pressure ratio, allowing for rapid adjustments in response to ambient conditions and preventing pressure ratio spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air is extracted from the compressor to provide turbine cooling air, then the turbine cooling requirement is met, but the compressor performance deteriorates due to reduced air flow
Solution Approach 1:
The invention divides the compressor air extraction into multiple stages (e.g., extracting air from both the high-pressure compressor and the compressor outlet). By segmenting the extraction points, the system can provide sufficient cooling air to the turbine while minimizing the impact on overall compressor performance, as air is taken from different pressure zones rather than a single point
Solution Approach 2:
The control system dynamically adjusts the extraction parameters (flow rate, pressure, temperature) based on ambient conditions and turbine cooling requirements. By changing these parameters in response to varying conditions, the system optimizes the balance between providing adequate turbine cooling and maintaining compressor productivity
2Manufacturing precision
If the ejector is sized for standard ambient conditions, then the design requirement is met, but the system cannot adapt to daily ambient temperature and pressure variations
Solution Approach 1:
The invention introduces dynamic control elements (regulatory valves, control systems) that allow the ejector system to adapt its operation to varying ambient conditions. The regulatory valve adjusts the flow of bypass air depending on ambient conditions, enabling the system to maintain proper cooling air pressure and temperature despite changes in ambient temperature and pressure
Solution Approach 2:
The control system continuously monitors ambient conditions and adjusts the bypass valve position and ninth stage air addition accordingly. This feedback mechanism ensures that the ejector system adapts to daily ambient variations, maintaining optimal turbine cooling air parameters while preventing compressor performance degradation
3Measurement precision
If the control system turns on or off the valve providing ninth stage compressor air to the ejector, then the pressure ratio control is improved, but immediate changes in cooling air to compressor discharge pressure ratio occur causing instability
Solution Approach 1:
The control system anticipates the immediate changes in pressure ratio that will occur when the ninth stage air valve is switched, and takes preliminary action by adjusting the bypass valve position in advance or concurrently. This preliminary adjustment of the bypass flow prevents destabilizing spikes in the cooling air to compressor discharge pressure ratio
Solution Approach 2:
The bypass air flow acts as an intermediary that mediates between the ninth stage air addition and the final cooling air pressure ratio. By adjusting the bypass flow, the system smooths out immediate changes and prevents destabilizing effects on the pressure ratio
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 ensures that the actual pressure ratio of turbine cooling air approaches the desired set point, reducing the risk of shutdowns and maintaining efficient compressor performance by quickly adjusting to changes in ambient conditions.
Implementation Method 1
An ejector has been used to combine air from different stages of a compressor to provide turbine cooling air. The extracted air from the thirteenth stage of the compressor, for example, may be at a pressure and temperature too great for the desired turbine cooling air. By employing an ejector, the low pressure and temperature air extracted from the ninth stage of a compressor is mixed with the high pressure and temperature air extracted from the thirteenth stage to provide an airflow at an intermediate pressure and temperature substantially matching the pressure and temperature required to cool the turbine stage.
Data Source
AI summary
A method for controlling the generation of turbine cooling air from air extracted from a compressor of a gas turbine including: extracting compressed air from a low pressure and a high pressure stage of the compressor; adding in an ejector the compressed air from the low pressure stage to the air from the high pressure stage and discharging the combined air as turbine cooling air; bypassing the ejector with a bypass portion of the extracted compressed air from the high pressure stage; in response to turning on the flow of extracted compressed air from the low pressure stage, changing a set point for an actual pressure ratio that includes a pressure of the turbine cooling air, and adjusting the bypass flow in response to the changed set point to cause the actual pressure ratio to approach the changed set point.