FLNG Vessel Heading Control via Dynamic Positioning
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Solution Overview
Problem
Current single point mooring systems for FLNG vessels are expensive, complex, and lack effective heading control, relying on weather conditions and requiring thrusters or tug boats for orientation, which is inefficient and costly.
Innovation Solution
A dynamic positioning control system with thrusters and a computer processor that uses real-time environmental and hull integrity data to generate heading control signals, allowing the FLNG vessel to maintain a desired heading during LNG production, independent of weather conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single point mooring system is used to moor the FLNG vessel, then the vessel can remain moored at a station keeping point, but the system becomes extremely large, complex and expensive
Solution Approach 1:
The patent extracts the heading control function from the mooring system by introducing a separate dynamic positioning system with thrusters. This separates the mooring function (station keeping) from the orientation function (heading control), allowing the mooring system to be simpler while heading is controlled independently through thruster-based dynamic positioning
Solution Approach 2:
The dynamic positioning system serves multiple functions: it provides both station keeping capability and heading control. The thrusters are used to maintain the vessel at the station keeping point while also controlling the vessel's orientation, eliminating the need for a complex single point mooring system designed to handle both functions
2Ease of operation
If thrusters or tug boats are used to control the heading of the FLNG vessel, then heading control can be achieved, but the operation becomes inefficient and costly
Solution Approach 1:
The FLNG vessel is equipped with its own dynamic positioning system with thrusters that enable self-controlled heading adjustment. The vessel can autonomously control its own orientation without requiring external tug boats, improving operational efficiency and reducing costs while maintaining full heading control capability
Solution Approach 2:
The system incorporates real-time monitoring of hull integrity data and environmental conditions, with feedback loops that automatically adjust thruster operation to maintain optimal heading. This automated feedback control improves operational efficiency by eliminating the need for manual tug boat operations and continuous human intervention
3Strength
If the FLNG vessel is designed to weathervane around the single point mooring, then the vessel can withstand storm forces, but the heading is dependent on weather conditions
Solution Approach 1:
The system transitions from a static weathervaning configuration to a dynamic heading control system. Thrusters provide active, real-time adjustment of vessel orientation, allowing the heading to be dynamically controlled independent of weather conditions while maintaining the ability to withstand storm forces through proper orientation
4Ease of operation
If a spread mooring system is used, then weathervaning can be prevented, but the system is only viable in benign locations with highly directional weather
Solution Approach 1:
The patent replaces the mechanical spread mooring system with a dynamic positioning system using thrusters. This substitution allows heading control through mechanical propulsion rather than through the geometric constraints of a spread mooring arrangement, enabling operation in locations with non-directional or harsh weather patterns where spread mooring would not be viable
Data Source
AI summary
A system for offshore production of LNG from an FLNG vessel includes a floating LNG vessel including a hull and a deck, a topsides hydrocarbon processing facility installed at or above the deck of the hull of the FLNG vessel, an FLNG vessel cargo containment system including one or more insulated FLNG vessel cryogenic storage tanks installed within the hull of the FLNG vessel, a dynamic positioning control system operatively associated with a system of thrusters onboard the FLNG vessel where the dynamic positioning control system maintains the FLNG vessel at a desired heading around a station keeping point during LNG production operations, and a computer processor for receiving a set of real-time monitored environmental data.