Double-Shell Tank Heat Penetration Reduction
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Solution Overview
Problem
Liquefied hydrogen carrier ships face significant heat penetration from the floor surface into the tank due to the tubular skirt support structure, which is not effectively insulated.
Innovation Solution
A double-shell tank design with a spherical inner shell and an outer shell, supported by tubular skirts where the second support member rises from the inner surface of the outer shell at a different location, increasing the heat penetration route and using materials with lower heat conductivity in specific portions of the support members to hinder heat transfer, and filling the space between the shells with boil-off gas or insulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single tubular skirt support structure is used to support the tank, then the structural simplicity and ease of manufacture are improved, but heat penetration from the floor surface into the tank increases significantly
Solution Approach 1:
The single support structure is divided into two separate tubular skirts: a first support member rising from the floor surface to support the outer shell, and a second support member rising from the inner surface of the outer shell to support the inner shell. This segmentation creates multiple heat penetration routes that are harder to insulate effectively, thereby reducing overall heat transfer to the liquefied gas.
Solution Approach 2:
A heat insulator is introduced as an intermediary material in the space between the inner and outer shells, specifically in the region where the support members are located. This heat insulator acts as a thermal barrier that reduces heat transfer from the outer shell to the inner shell, thereby protecting the liquefied gas from heat penetration.
2Object-affected harmful factors
If the tank is entirely covered by an insulating layer, then heat insulation is improved, but the structural complexity increases
Solution Approach 1:
Instead of uniformly covering the entire tank with insulating material, the heat insulator is strategically placed only in the space between the inner and outer shells at the support member locations. This localized insulation approach addresses the specific heat penetration pathways without requiring complete coverage, thereby reducing structural 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
This configuration significantly reduces heat penetration from the floor surface into the tank by lengthening the heat transfer path and utilizing materials with lower heat conductivity, thereby maintaining the temperature of the liquefied gas effectively.
Implementation Method 1
the length of the heat penetration route can be increased by an amount corresponding to the distance between the portions of the first and second support members that extend along the outer shell. As such, the heat penetration from the floor surface into the double-shell tank can be reduced.
Implementation Method 2
the second support member may include an upper portion made of the same material as the inner shell, a lower portion made of the same material as the outer shell, and a middle portion made of a material having a lower heat conductivity than the materials of the inner and outer shells. In this configuration, the second support member can easily be joined to the inner and outer shells, and heat transfer through the second support member can be hindered by the middle portion of the second support member.
Data Source
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AI summary
A liquefied gas storage structure includes a double-shell tank 2 including a spherical inner shell 3 storing a liquefied gas and an outer shell 4 enclosing the inner shell 3. The liquefied gas storage structure further includes a first support member 6 rising from a floor surface 11a and supporting the outer shell 4 and a second support member 5 rising from an inner surface of the outer shell 4 at a location different from that of the first support member 6, the second support member 5 supporting the inner shell 3.