Cryogenic Tank Bottom Stress Mitigation via Elastic Intermediate Layer
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Solution Overview
Problem
In LNG tanks using rigid polyurethane foam for heat insulation, material differences can lead to step formations between foam and pearlite concrete, causing rapid deformation and localized bending stress on the bottom portion, potentially applying significant loads.
Innovation Solution
Incorporating an intermediate member with a cover portion between the outer and inner support portions, formed of elastic material, to mitigate deformation and distribute stress evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If rigid polyurethane foam is used for heat insulation in the support portion, then heat insulation performance is improved, but step parts are generated between foam and pearlite concrete due to material characteristic differences, causing rapid local deformation and significant load on the bottom portion
Solution Approach 1:
The patent introduces an intermediate member made of elastic material positioned between the rigid polyurethane foam and the pearlite concrete. This intermediary component absorbs the differential deformation caused by material characteristic differences, preventing step part formation and protecting the bottom portion from rapid local deformation and excessive loading.
Solution Approach 2:
The patent changes the material parameter of the support portion by incorporating an elastic material as an intermediate layer. This modifies the overall mechanical properties of the support structure, allowing it to accommodate thermal expansion and contraction differences between the foam and concrete without generating harmful stresses.
2Temperature
If rigid polyurethane foam is used for heat insulation, then heat insulation performance is improved, but the foam gradually precipitates (creep deformation) over time, generating step parts and applying significant load to the bottom portion
Solution Approach 1:
The patent applies beforehand cushioning by pre-installing the elastic intermediate member to compensate for future creep deformation of the rigid foam. This elastic layer acts as a buffer that absorbs the dimensional changes occurring over time, preventing step part formation and protecting the bottom portion throughout the tank's service life.
Solution Approach 2:
The elastic intermediate member serves as a mediator between the time-dependent foam material and the stable concrete structure. It accommodates the gradual precipiation of the foam without transferring harmful stresses to the bottom portion, thereby extending the operational lifespan of the tank.
3Manufacturing precision
If a step part is generated between support portions, then deformation is concentrated at the boundary, but the cover portion distributes this deformation to prevent rapid local deformation of the intermediate member and bottom portion
Solution Approach 1:
The patent employs a flexible elastic material as the cover portion that can deform to accommodate step parts while distributing stresses. This flexible layer conforms to the underlying irregularities in the support structure, preventing stress concentration and protecting the intermediate member and bottom portion from rapid local deformation.
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
Prevents significant loads from being applied to the bottom portion by gently deforming the intermediate member, reducing localized bending stress and extending the tank's operational lifespan.
Implementation Method 1
the inner support portion which is disposed to be adjacent to an inner side of the outer support portion, includes a heat insulating layer formed of an elastic material
Data Source
AI summary
A cryogenic liquid tank (1) includes a reservoir (5) that includes a bottom portion (5a, 5a1, or 5a2) and a side wall (5b), a support portion (4) that supports the reservoir (5), and an intermediate member (10) that is provided between the reservoir (5) and the support portion (4). The support portion (4) includes an outer support portion (4b) which supports the side wall (5b), and an inner support portion (4a) which is disposed to be adjacent to an inner side of the outer support portion (4b), includes a heat insulating layer formed of an elastic material, and supports the bottom portion (5a, 5a1, or 5a2) of the reservoir (5). A cover portion (9a, 9a1, or 15) covering a boundary between the outer support portion (4b) and the inner support portion (4a) is provided between the support portion (4) and the intermediate member (10).