Turbocompressor Startup Control via Antisurge Valve Management
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Solution Overview
Problem
The existing startup procedures for turbocompressors require high shaft power, leading to slower startup times and potential driver overload, especially due to unknown surge limit curves at low rotational speeds and the need to maintain the antisurge valve fully open until valid pressure and flow sensor signals are achieved.
Innovation Solution
The antisurge valve is maintained fully open until predetermined signal strengths are realized from pressure and flow sensors, then ramped closed at a controlled rate to minimize energy consumption and avoid the surge region, with the control system managing the compressor's operating point to ensure safe startup, regardless of the antisurge controller's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the antisurge valve is maintained fully open during startup, then surge is avoided and safe operation is ensured, but high shaft power is required and startup time increases
Solution Approach 1:
The control system performs preliminary actions by monitoring pressure and flow sensor signals before fully opening the antisurge valve. The valve is opened only after valid sensor signals are confirmed, and is ramped closed after a predetermined time period, reducing unnecessary power consumption while maintaining surge protection during the critical startup phase
Solution Approach 2:
The antisurge valve transition from static fully-open position to dynamic controlled operation. The valve is ramped closed after a predetermined time period based on real-time sensor feedback, allowing the system to adapt valve position to actual operating conditions and reduce power consumption as startup progresses
2Reliability
If the antisurge valve is maintained fully open until minimum operating speed is reached, then surge is avoided, but driver overload may occur and startup becomes slower
Solution Approach 1:
The control system implements preliminary timing-based control by ramping the antisurge valve closed after a predetermined time period from startup initiation, rather than waiting for minimum operating speed. This preliminary action reduces startup time while the control system continues to monitor operating conditions to ensure surge avoidance
Solution Approach 2:
The control system uses feedback from pressure and flow sensors to monitor the compressor operating point during startup. The antisurge valve is controlled based on real-time feedback to maintain the operating point away from the surge limit, enabling faster startup while ensuring surge avoidance
3Power
If the antisurge valve is ramped closed after predetermined time, then energy consumption is minimized and startup time reduced, but surge limit curve uncertainty at low speeds remains
Solution Approach 1:
The control system continuously monitors the compressor operating point using feedback from pressure and flow sensors during the startup phase. This real-time feedback enables the system to detect approaching surge conditions and adjust the antisurge valve accordingly, compensating for the lack of known surge limit curve data at low rotational speeds
Solution Approach 2:
The control system performs preliminary monitoring and control actions during startup before the antisurge valve is ramped closed. By establishing baseline operating characteristics and validating sensor signals during this preliminary phase, the system builds necessary information about compressor behavior at low speeds while minimizing energy consumption
Data Source
AI summary
A control method and apparatus for startup of turbocompressors to avoid overpowering a driver of the turbocompressor. In a first embodiment, the control system monitors input signals from transmitters of various control inputs. When the input signals exceed threshold values, the control system begins to close the antisurge valve. In a second embodiment, the antisurge valve begins to close after a predetermined time measured from the time startup is initiated. In both embodiments, the antisurge valve continues to ramp closed until the compressor has reached its operating zone, or until the compressor's operating point reaches a surge control line, at which point the antisurge valve is manipulated to keep the compressor from surging.