LNG Inner Tank Support Structure for Ship Thermal Expansion
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Solution Overview
Problem
Conventional LNG storage tank structures for ships face stress concentration issues due to temperature changes, as they can only expand or contract in the lengthwise direction, limiting the dispersion of stress in the circumferential direction, which can lead to damage at fixed portions.
Innovation Solution
An inner tank supporting structure with a sliding main supporter, a fixing main supporter, and sub supporters that allow the inner tank to expand or contract in both lengthwise and circumferential directions, using elongated sliding grooves, round grooves, and buffering members to distribute stress evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the inner tank is fixed at both sides to the outer tank, then the structure is stable, but the inner tank cannot expand or contract in the circumferential direction, causing stress concentration
Solution Approach 1:
The supporting structure is divided into multiple independent supporters (first supporting member, second supporting member, third supporting member, fourth supporting member) distributed around the inner tank. Each supporter independently supports a portion of the inner tank, allowing localized movement while maintaining overall structural stability. This segmentation enables the tank to expand/contract circumferentially without concentrating stress at single fixed points.
Solution Approach 2:
The supporters are designed with dynamic characteristics that allow them to accommodate thermal expansion and contraction. The supporters can move relative to each other and to the outer tank, transitioning from a completely fixed static structure to a dynamic system that adapts to temperature changes. This dynamic capability prevents stress concentration while maintaining structural integrity.
2Ease of operation
If the sliding supporter has sliding grooves in the lengthwise direction, then the inner tank can move in the lengthwise direction, but the circumferential direction movement is restricted, limiting stress dispersion
Solution Approach 1:
The supporting structure provides movement freedom in multiple dimensions. In addition to the lengthwise direction movement enabled by sliding grooves, the structure allows circumferential direction movement through the arrangement of multiple supporters and their relative movement capabilities. This multi-dimensional movement capability enables comprehensive stress dispersion in all directions, resolving the limitation of single-direction movement.
3Strength
If both sides of the inner tank are fixed to the outer tank, then the structure is rigid, but the inner tank cannot contract or expand in the circumferential direction, limiting stress control
Solution Approach 1:
The supporting structure utilizes parameter changes related to thermal expansion and contraction. The supporters are designed to accommodate changes in the inner tank's dimensions due to temperature variations. By allowing controlled movement and deformation of the supporters, the structure adapts to thermal parameter changes while maintaining overall structural strength and rigidity.
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 design enables the inner tank to expand or contract freely in both directions, preventing stress concentration on fixed portions and ensuring safe operation during temperature changes.
Implementation Method 1
the inner tank 2 is contracted or expanded by a temperature change
Implementation Method 2
the inner tank 2 is contracted or expanded by a temperature change
Data Source
Figure 1~2
Figure 3a
Figure 3b
AI summary
The present invention relates to an inner tank supporting structure for an LNG storage tank for a ship, which does not restrict expansion or contraction of an inner tank in circumferential and lengthwise directions while the inner tank is expanded or contracted due to a temperature change caused by storage and discharge of LNG. The inner tank supporting structure for the LNG storage tank which has a cylindrical outer tank and a cylindrical inner tank, includes: a sliding main supporter mounted at one side of a bottom of the outer tank so as to fix the center of a bottom surface of the inner tank, the sliding main supporter having elongated sliding grooves formed in the lengthwise direction of the inner tank; a sliding main supporter mounted at the other side of the bottom of the outer tank so as to fix the center of the bottom surface of the inner tank, the sliding main supporter having round grooves; and a sub supporter mounted at the bottom of the outer tank so as to support the bottom surface of the inner tank, wherein the bottom surface of the inner tank is not fixed to the sub supporter.