Subsea Compressor Anti-Surge Control via Magnetic Bearing Data
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Solution Overview
Problem
Subsea gas compressors with active magnetic bearings face challenges in rapidly responding to flow reductions, leading to potential surge conditions due to delayed signal pathways and reaction times in anti-surge control systems, which can result in overheating, vibration, and damage.
Innovation Solution
Implementing an anti-surge control method that uses active magnetic bearing controller data, such as rotor position and magnetic flux, to determine a force representing value and switch the anti-surge valve open when exceeding a threshold, ensuring rapid transition to anti-surge mode, with an anti-surge valve switching actuator overriding traditional control systems for immediate action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional anti-surge control systems are used with subsea compressors, then the system structure is simple and easy to implement, but the response time is delayed due to long signal pathways, leading to potential surge conditions
Solution Approach 1:
The patent merges the anti-surge control functionality with the existing active magnetic bearing controller. The magnetic bearing controller, which already exists for rotor support, is enhanced to also perform anti-surge control by monitoring rotor position and calculating axial force, eliminating the need for separate sensors and control pathways.
Solution Approach 2:
The active magnetic bearing controller is designed to serve multiple functions: both rotor positioning/support and anti-surge control. This multi-functional approach allows the same hardware and control system to address both rotor stability and surge prevention, reducing overall system complexity while improving response speed.
2Loss of time
If traditional pressure and flow sensors are used for anti-surge control, then the control system is straightforward, but the signal pathways are long and response is delayed
Solution Approach 1:
The patent extracts the anti-surge control functionality from the traditional sensor-based system and integrates it directly into the magnetic bearing controller. This eliminates the need for separate pressure and flow sensors and their associated signal pathways, reducing both response time and system complexity.
Solution Approach 2:
The rotor position signal from the magnetic bearing system serves as an intermediary parameter that indirectly indicates surge conditions. By monitoring changes in rotor position and calculating axial force, the system detects surge tendencies without requiring direct pressure or flow measurements, enabling faster response.
3Productivity
If the anti-surge valve is controlled by traditional control systems, then the control logic is simple, but the valve switching is not rapid enough to prevent surge
Solution Approach 1:
The patent combines the anti-surge valve control function with the magnetic bearing control system. The same controller that manages rotor positioning also triggers the anti-surge valve based on rotor position analysis, enabling rapid valve switching through the existing fast-response magnetic control infrastructure.
Solution Approach 2:
The system performs preliminary analysis of rotor position data to detect surge tendencies before they develop into full surge conditions. By continuously monitoring axial force variations and predicting surge risk, the system can trigger the anti-surge valve in advance, preventing surge rather than responding to it after occurrence.
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 solution enables fast and redundant anti-surge control, preventing compressor surge by rapidly adjusting the anti-surge valve, reducing the risk of damage from surge conditions and maintaining stable operation in subsea environments.
Implementation Method 1
a compressor rotor supported by active magnetic bearings for contact-free rotation
Implementation Method 2
A valve normally closed in the recycle line is arranged to be shifted into open state in case of insufficient flow, switching the compressor from normal operation into what can be called an anti-surge operational mode
Data Source
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AI summary
A subsea compression system and method is disclosed, the compression system arranged to be switched from normal operation into an anti-surge operational mode. The compression system comprises a compressor rotor (3) supported for contact-free rotation by active magnetic bearings (20, 21, 22), an active magnetic bearing (AMB) controller (24) to maintain the position of the compressor rotor (3) relative to non- rotating parts of the compressor, an anti-surge valve (25) normally closed in a recycle line (26) setting a compressor outlet (10) in flow connection with a compressor inlet (9) in an open state of the anti-surge valve, wherein the active magnetic bearing controller (24) is operatively connected to the anti-surge valve (25). The method comprises determining, using AMB control data, a value representing a force acting on the compressor rotor from the process load, comparing the force representing value to a threshold value indicative of a surge condition, and in response to the force representing value exceeding the threshold value switching the anti- surge valve into the open state.