Floating Loading Arm Height Adjustment for LNG Transfer Stability
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Solution Overview
Problem
The challenge in maintaining a stable connection between a floating LNG FPSO and an LNG carrier due to excessive vertical relative movements caused by sea conditions, leading to difficulties in connecting the loading arm and potential impacts or loosening of the coupling.
Innovation Solution
A floating type structure equipped with a loading arm ascending and descending device, a connection pipe, and a drain pipe system that allows for height adjustment and fluid discharge, facilitating maintenance and pressure control through a single drain pipe, and enabling the release of couplings for repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the loading arm is connected to transfer LNG between floating vessels, then LNG transfer function is achieved, but excessive vertical relative movements due to sea conditions cause connection instability and coupling loosening
Solution Approach 1:
The loading arm is designed with dynamic adjustment capability through a height adjusting device that actively compensates for vertical relative movements between vessels. The loading arm can ascend and descend to maintain optimal connection height, adapting to changing sea conditions and vessel positions in real-time
Solution Approach 2:
A connection pipe with flexible coupling mechanism is introduced as an intermediary between the loading arm and the vessel manifold. This coupling allows for relative movement absorption while maintaining the LNG transfer connection, acting as a buffer against vertical displacement forces
2Reliability
If the loading arm height is adjusted to compensate for vertical movements, then connection stability is improved, but the complexity of the height adjusting device increases
Solution Approach 1:
The height adjusting device utilizes hydraulic cylinders to control the loading arm's vertical position. This pneumatic-hydraulic mechanism provides smooth, controlled movement with relatively simple actuation, avoiding complex mechanical linkages while achieving reliable height adjustment
Solution Approach 2:
The system changes the height parameter of the loading arm dynamically based on detected vertical displacement. By continuously adjusting this single parameter through a relatively simple actuator, the system achieves connection stability without requiring complex multi-parameter control mechanisms
3Reliability
If the cylinder is permanently coupled for continuous operation, then operational reliability is maintained, but maintenance and repair of the cylinder become difficult
Solution Approach 1:
The cylinder assembly is segmented into separable components with standardized coupling interfaces. The coupling mechanism between the cylinder and loading arm can be disconnected, allowing the cylinder to be removed as a separate unit for maintenance or replacement without dismantling the entire loading arm system
Solution Approach 2:
The coupling design incorporates preliminary alignment features and quick-connect mechanisms that facilitate rapid assembly and disassembly. Maintenance personnel can quickly couple or decouple the cylinder using pre-positioned alignment pins and locking mechanisms, minimizing downtime during maintenance operations
4Adaptability or versatility
If multiple drain pipes are installed for fluid discharge and pressure control, then functional completeness is achieved, but the device complexity and maintenance requirements increase
Solution Approach 1:
The drain pipe system is designed with multi-functional capability where a single integrated drain structure serves multiple purposes: discharging accumulated fluid from the hull, venting pressure from the plunger base, and providing access for maintenance. This universal drain component replaces what would otherwise require multiple separate pipes and valves
Solution Approach 2:
The drain function and pressure control function are merged into a single integrated drain pipe system. The drain pipe is configured to simultaneously handle fluid discharge from multiple sources and provide pressure equalization, combining several functions into one simplified structural element that reduces overall system complexity
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
The solution ensures a stable connection between the FPSO and carrier by compensating for height differences and allows for efficient fluid discharge and pressure management, simplifying maintenance and repair processes.
Implementation Method 1
a cylinder which connects the plunger to the plunger base and adjusts a height of the loading arm
Data Source
Figure 1
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AI summary
Provided herein is a loading structure. The floating type structure includes a loading arm, a plunger connected to the loading arm, a plunger base which is connected to a recess formed in the hull and into which the plunger is inserted, a cylinder which connects the plunger to the plunger base and adjust a height of the loading arm, and a cylinder cover including a first region in which an opening is formed and a second region in which an opening is not formed, connected to the cylinder through the opening, and inserted into a connection groove formed in the recess to couple the cylinder to the recess.