Double-Shell Tank Partition Wall for Liquefied Gas Carrier
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Solution Overview
Problem
The existing double-shell tank designs for liquefied gas carriers face challenges in reducing heat entry through the outer ring, partition wall, and inner ring while maintaining sufficient strength at their joints, particularly due to thermal contraction of the inner shell.
Innovation Solution
A double-shell tank configuration with a cylindrical partition wall of varying thickness, where the middle portion is thinner than the end portions, and the outer circumferential surface is recessed inward, reducing heat entry and allowing for S-shaped deformation to manage thermal contraction stresses, thus maintaining joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the partition wall is made thinner to reduce heat entry, then thermal insulation performance is improved, but joint strength between the partition wall and rings deteriorates
Solution Approach 1:
The partition wall employs variable thickness design where the middle portion is thinner to reduce heat conduction, while the upper and lower end portions are thicker to ensure sufficient joint strength with the inner and outer rings. This local differentiation of thickness allows simultaneous optimization of thermal insulation performance and structural integrity at different locations of the partition wall.
2Loss of energy
If the inner shell is allowed to thermally contract, then thermal insulation is maintained, but stress on pipes and shell structure increases
Solution Approach 1:
The bellows structure is incorporated in the outer shell dome to provide dynamic adaptability. When the inner shell contracts thermally, the bellows can deform elastically to accommodate the dimensional change, converting the rigid constraint into a flexible connection that absorbs thermal stress without transmitting excessive force to the pipes and shell structure.
Solution Approach 2:
The bellows changes its physical state from a rigid cylindrical structure to a flexible, deformable structure that can expand and contract. This parameter change in structural rigidity allows the outer shell to adapt to the thermal contraction of the inner shell, reducing stress concentration while maintaining the vacuum insulation layer's integrity.
3Loss of energy
If the second vacuum space is partitioned into upper and lower spaces, then heat entry is reduced, but device complexity increases
Solution Approach 1:
The partition wall serves multiple functions simultaneously: it divides the second vacuum space into upper and lower portions to reduce heat conduction paths, provides structural support by connecting the inner and outer rings, and accommodates variable thickness design for optimized thermal and mechanical performance. This multi-functionality reduces the need for additional separate components.
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 effectively reduces heat entry through the outer ring, partition wall, and inner ring while preserving the structural integrity of the joints, enhancing the thermal insulation and mechanical stability of the double-shell tank.
Implementation Method 1
a vacuum thermal insulation layer is formed between an inner shell and an outer shell
Implementation Method 2
The space between the inner shell main part and the outer shell main part is a first vacuum space, and the space between the inner shell dome and the outer shell dome is a second vacuum space
Implementation Method 3
When the liquefied gas is fed into the inner shell, thermal contraction of the inner shell occurs
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A double-shell tank includes: an inner shell including an inner shell main part and an inner shell dome; an inner shell manhole; an outer shell including an outer shell main part and an outer shell dome, the outer shell main part surrounding the inner shell main part with a first vacuum space formed between the outer shell main part and the inner shell main part, the outer shell dome surrounding the inner shell dome with a second vacuum space formed between the outer shell dome and the inner shell dome; an outer shell manhole; a bellows incorporated in the outer shell dome, such that the bellows divides the outer shell dome into a lower fixed portion and an upper movable portion; an inner ring fixed to the inner shell dome in the second vacuum space; an outer ring fixed to the movable portion of the outer shell dome in the second vacuum space, the outer ring being positioned below the inner ring; and a cylindrical partition wall that couples the inner ring and the outer ring, and partitions off the second vacuum space into an upper vacuum space and a lower vacuum space. A middle portion of the partition wall is less thick than both end portions of the partition wall.