Steam Turbine Pressure Control via Bypass Valves
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Solution Overview
Problem
Current steam turbine pressure control systems in combined cycle plants are complex, prone to human error, and require high installation, testing, and maintenance costs, making them inefficient and unreliable, especially in dynamic operating conditions such as frequent shutdowns and varying load requests.
Innovation Solution
A control device with a bypass system that regulates steam flow and pressure across multiple sections of the steam turbine, using a sliding pressure control mechanism and multiple valve configurations to adapt to different operating conditions, allowing for automated pressure management based on real-time measurements and plant status signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional steam turbine pressure control systems are used, then pressure control functionality is provided, but the system complexity increases and reliability decreases due to human error and operational complexity
Solution Approach 1:
The control device automatically detects plant operating conditions through sensors and status signals, selects appropriate operating modes, and adjusts valve positions without human intervention. The system serves itself by autonomously managing pressure control based on real-time measurements of steam flow rates, pressures, and gas turbine loads, eliminating the need for manual operator decisions and reducing human error.
Solution Approach 2:
The control device continuously receives feedback from sensors measuring steam flow rates, pressures, and plant status signals. Based on this feedback, the system dynamically adjusts the positions of control valves to maintain optimal pressure conditions. The feedback loop enables automatic adaptation to changing operating conditions, improving both reliability and responsiveness.
2Ease of manufacture
If traditional pressure control systems are used, then basic pressure regulation is achieved, but installation, testing, and maintenance costs increase along with operational complexity
Solution Approach 1:
The control device is designed to handle multiple operating modes (single gas turbine, dual gas turbines, startup, shutdown, load rejection) through a single integrated system. The same control device manages both pressure regulation and mode selection, eliminating the need for separate specialized systems for different operating conditions. This multi-functionality reduces overall system complexity while maintaining comprehensive control capabilities.
Solution Approach 2:
The control device combines previously separate functions into a unified system: mode selection, pressure setpoint determination, and valve control are merged into one integrated control unit. This consolidation simplifies installation and maintenance by reducing the number of separate components and interfaces, while the modular architecture allows for easier troubleshooting and repair.
3Productivity
If manual operation and preparation procedures are used, then operators can manage plant operations, but error risks increase and productivity decreases due to time-consuming procedures
Solution Approach 1:
The control device automatically performs all pressure control operations without requiring manual operator intervention. The system autonomously monitors plant conditions, selects appropriate operating modes, calculates optimal pressure setpoints, and adjusts valve positions in real-time. This automation eliminates time-consuming manual procedures and reduces the risk of human error while improving operational efficiency.
Solution Approach 2:
The control device pre-determines optimal pressure setpoints and control strategies based on detected plant conditions before actual pressure adjustments are needed. The system proactively prepares control actions by analyzing current operating parameters and predicting required adjustments, enabling smooth and timely pressure regulation without waiting for manual operator assessment and decision-making.
4Adaptability or versatility
If fixed pressure control methods are used, then simple control logic is maintained, but adaptability to varying load requests and operating conditions deteriorates
Solution Approach 1:
The control device dynamically adapts its control strategy based on real-time plant operating conditions. The system automatically transitions between different operating modes (single gas turbine, dual gas turbines, startup, shutdown, load rejection) and adjusts pressure setpoints dynamically according to steam flow rates and gas turbine loads. This dynamic behavior enables the system to adapt to varying load requests while maintaining relatively simple control logic through automated mode selection.
Solution Approach 2:
The control device changes control parameters (pressure setpoints, valve positions) based on detected operating conditions. The system adjusts the setpoint pressure values dynamically according to the operating mode and current plant parameters such as steam flow rates and gas turbine loads. This parameter adaptation enables versatile operation across different conditions without requiring complex control algorithms, as the system simply selects appropriate pre-defined parameter sets based on current state.
Data Source
AI summary
A control device of a steam turbine of a combined cycle plant includes an acquisition module (13), for acquiring measures of operative quantities (QHP1, QHP2, PHP) of a combined cycle plant (1) including a steam turbine (5) and a first and second steam feeding systems (100, 101). The device further includes a plurality of calculation modules (47-56, 47'-56'), configured for determining, according to corresponding control modes: a pressure set point (PHPCV) for a high-pressure inlet valve (25); a pressure set point (PIPCV) for an intermediate-pressure inlet valve (30) of the steam turbine (5); and pressure set points (PHPBP1, PHPBP2, PIPBP1, PIPBP2) for high-pressure bypass valves (28a, 28b) and intermediate-pressure bypass valves (33a, 33b). Furthermore, a supervisor module (45) is configured to detect an operating condition of the plant (1) on the basis of operative quantities (QHP1, QHP2, PHP) acquired by the acquisition module (13) and selectively activate one of the calculation modules (47-56, 47'-56') in response to the detected operating condition.