Multilobe LNG Tank Support System Managing Thermal Expansion
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Solution Overview
Problem
The challenge of supporting large LNG tanks on ships is exacerbated by the significant thermal expansion and contraction due to the low storage temperature of liquefied natural gas, which complicates their attachment to the ship's hull and requires innovative solutions to manage mechanical stress and stability.
Innovation Solution
A multilobe tank arrangement with a specific support system that allows for expansion and contraction in both lateral and longitudinal directions, utilizing multiple supports to prevent movement in specific directions and ensure the tank's stability, including a third and fourth support to prevent spinning, allowing for symmetric shrinkage and maintaining the center of gravity's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the tank is firmly attached to the ship's hull to ensure stability, then the tank's positional stability is improved, but the tank cannot accommodate thermal expansion and contraction, leading to mechanical stress and potential failure
Solution Approach 1:
The support system transitions from a static fixed attachment to a dynamic adjustable system. The supports are designed to allow movement in specific directions (longitudinal and lateral) while maintaining vertical support, enabling the tank to adapt its position dynamically in response to thermal expansion and contraction without compromising overall stability or causing mechanical stress.
Solution Approach 2:
The support system changes the physical parameters of the tank's positional constraints. By allowing movement in longitudinal and lateral directions while maintaining vertical support, the system changes the degrees of freedom of the tank, enabling it to accommodate dimensional changes due to thermal effects while remaining securely attached to the hull.
2Weight of moving object
If the tank is designed as a multilobe shape to reduce material usage and weight, then the tank's structural efficiency is improved, but the complexity of supporting and securing the tank increases
Solution Approach 1:
The multilobe tank is divided into multiple sections (at least three tank sections arranged in a row in the lateral direction), each supported by independent support structures. This segmentation allows each section to be supported individually, simplifying the overall support system while accommodating the complex multilobe geometry and reducing material usage through optimized structural design.
Solution Approach 2:
Different support configurations are applied to different sections of the multilobe tank based on their specific structural requirements. The support system provides localized support characteristics tailored to each tank section, allowing for optimized weight distribution and structural efficiency while maintaining overall tank integrity.
3Area of stationary object
If the tank sections are arranged in a row in the lateral direction to optimize space utilization, then the tank's space efficiency is improved, but the risk of tank sections moving relative to each other increases
Solution Approach 1:
Multiple support functions are combined into an integrated support system that simultaneously provides vertical support, prevents longitudinal movement, prevents lateral movement, and allows thermal expansion. The support structure integrates these multiple functions into a single cohesive system that maintains the relative positions of tank sections while accommodating thermal effects.
Solution Approach 2:
The support system acts as an intermediary between the tank sections and the ship's hull, providing a controlled interface that allows the tank to move thermally while maintaining secure attachment. The support structure mediates the interaction between the tank's thermal expansion and the hull's fixed structure, preventing direct transmission of stress while maintaining positional stability.
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 support system effectively manages thermal expansion and contraction, ensuring the tank's stability and secure attachment to the ship's hull, reducing the risk of mechanical failure and maintaining the tank's center of gravity, thus enhancing safety and operational efficiency.
Implementation Method 1
the dimensions of a tank that is in use and an empty tank that can be at a temperature of +30° C. can differ significantly from each other
Implementation Method 2
significant thermal expansion and contraction due to the low storage temperature of liquefied natural gas
Data Source
AI summary
An exemplary tank arrangement for storing liquefied natural gas includes a multilobe tank having at least three tank sections arranged in a row in a lateral direction, wherein each tank section is supported against a support surface with a first support allowing movement of the tank relative to the support surface in the longitudinal direction and with a second support, at least one of the second supports preventing movement of the tank relative to the support surface in the longitudinal direction. One tank section has a third support, which allows movement of the tank relative to the support surface in the longitudinal direction and prevents movement in the lateral direction. The first and second supports allow shrinkage and expansion of the tank in the lateral direction.