LNG Transfer System Mobile Chassis Selective Inerting
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Solution Overview
Problem
Current LNG transfer systems between ships are inefficient due to lengthy inerting and cooling processes, which prolong the connection and preparation phases before actual transfer can commence, especially since the entire length of flexible ducts on the supplier ship needs to be inerted and cooled, leading to suboptimal transfer conditions.
Innovation Solution
A transfer system featuring a hoisting device, a mobile chassis, and ducts for LNG and inert gas, with on-board pipes and valves that allow for selective inerting and cooling, enabling the system to remain ready for use during inerting and reducing the need for extensive duct inerting, thus streamlining the pre-transfer operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire length of flexible ducts on the supplier ship is inerted, then safety during LNG transfer is improved, but the time required for pre-transfer operations increases significantly
Solution Approach 1:
The duct system is divided into two segments: rigid ducts connected to storage tanks and flexible ducts connected to the mobile chassis. Inerting is applied selectively to the rigid ducts only, while the flexible ducts are excluded from the inerting process. This segmentation allows safety-critical areas to be protected while avoiding the time-consuming inerting of the entire duct length.
Solution Approach 2:
Different parts of the duct system are treated differently regarding inerting. The rigid ducts connected to LNG storage tanks are inerted to ensure safety, while the flexible ducts are kept non-inerted to reduce preparation time. This local differentiation of quality (inerted vs. non-inerted zones) resolves the contradiction between safety and time efficiency.
2Reliability
If LNG is circulated in the ducts of the supplier ship to maintain temperature, then LNG transfer conditions are improved, but the ducts must be cooled after inerting, extending the preparation time
Solution Approach 1:
The rigid ducts are inerted in advance before the flexible ducts are connected to the client ship. This preliminary inerting allows the temperature management process to proceed independently without the constraint of subsequent cooling requirements, as the flexible ducts (which would require cooling) are not inerted in the first place.
Solution Approach 2:
The duct system is segmented such that only rigid ducts are inerted, while flexible ducts remain outside the inerted zone. This eliminates the need for cooling the flexible ducts after inerting, as they were never subjected to inert gas treatment. The segmentation allows temperature management and inerting to be decoupled.
3Productivity
If the mobile chassis supports the on-board pipes and allows selective inerting, then the complexity of the system increases, but the overall transfer process becomes more efficient
Solution Approach 1:
The mobile chassis serves multiple functions: it supports the on-board pipes, enables selective inerting by positioning the flexible ducts outside the inerted zone, and facilitates connection to the client ship. This multi-functionality justifies the increased structural complexity by delivering multiple benefits simultaneously.
Solution Approach 2:
The mobile chassis acts as an intermediary between the rigid duct system and the flexible duct system. It provides the interface that allows selective inerting while maintaining operational flexibility, mediating between the safety requirements of the rigid ducts and the efficiency requirements of the flexible ducts.
Data Source
AI summary
A system for transferring liquid natural gas from a ship to a facility, the transfer system comprising: a hoisting device which is designed to be secured on the deck of the ship; a mobile chassis, which is supported by the hoisting device; a first on-board pipe, for transferring liquid natural gas from the ship to the facility, said first on-board pipe being supported by the mobile chassis; and a second on-board pipe for the transport of inert gas, said second on-board pipe being supported by the mobile chassis comprising a first connection element which is associated with the second duct, and being connected to the first on-board pipe between the valve and the second connection element of the first on-board pipe.