Low Temperature Liquid Tank Inner Support Height Design
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Solution Overview
Problem
Low temperature liquid tanks using water- or cyclopentane-foamed heat insulation face issues with creep, leading to a gradual sinking of the upper surface of the support portion, causing a level difference and increased bending stress on the bottom portion, which may require large-scale maintenance.
Innovation Solution
A low temperature liquid tank design with an inner support portion having a heat insulation that creeps under load, where the initial height of its upper surface is set to keep maximum bending stress on the bottom plates within allowable limits, using a rigid plastic foam and a height setting plate, and optionally chamfering the outer support portion's edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water- or cyclopentane-foamed heat insulation is used in the support portion, then cold insulating performance is improved, but rigidity deteriorates causing creep and sinking of the upper surface
Solution Approach 1:
The patent changes the physical parameters of the heat insulation material by specifying precise density ranges (20-80 kg/m³ for rigid plastic foam, 10-50 kg/m³ for foamed glass) and thickness parameters to achieve the optimal balance between thermal insulation performance and mechanical rigidity, preventing creep while maintaining cold insulating properties
Solution Approach 2:
The patent employs composite material structures by combining different types of heat insulation materials (rigid plastic foam and/or foamed glass) with concrete in the support portion, creating a composite system that leverages the thermal insulation properties of foam materials while utilizing the high rigidity of concrete to prevent creep and surface sinking
2Stability of the object's composition
If the initial height of the inner support portion is increased to compensate for creep, then the level difference is reduced, but bending stress on the bottom plates increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the expected creep amount based on heat insulation material properties and tank load, then setting the initial height of the inner support portion accordingly before the tank enters service, ensuring that the upper surface maintains an appropriate level relationship with the outer support portion throughout the service life without excessive bending stress
Solution Approach 2:
The patent utilizes parameter changes by establishing specific mathematical relationships between the initial height of the inner support portion, the thickness of heat insulation, and the allowable bending stress of bottom plates, allowing optimization of the initial height parameter to balance level stability and stress control
3Strength
If foam glass is used instead of water- or cyclopentane-foamed heat insulation, then rigidity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by specifying density ranges and thickness parameters for different heat insulation materials, allowing selection of more manufacturable materials like rigid plastic foam with appropriate density control, thereby reducing manufacturing complexity while maintaining the necessary rigidity through optimized parameters
Solution Approach 2:
The patent considers using more cost-effective and easier to manufacture materials (rigid plastic foam, water- or cyclopentane-foamed heat insulation) with controlled density and thickness parameters, accepting that these materials may require more frequent monitoring or replacement compared to durable foam glass, thus prioritizing ease of manufacture and cost-effectiveness
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 prevents excessive load on the bottom portion by managing the height difference between inner and outer support surfaces, ensuring the bending stress remains within safe limits, thus reducing the need for large-scale maintenance during the tank's service life.
Implementation Method 1
an inner support portion (12) disposed inside the outer support portion (11) and having a heat insulation (4b1) in which creep occurs when a load is applied to the heat insulation (4b1)
Data Source
AI summary
A low temperature liquid tank includes: a storage tank having a bottom portion obtained by joining a plurality of bottom plates; and a support portion supporting the bottom portion. The support portion includes: an outer support portion supporting a margin of the storage tank; and an inner support portion disposed inside the outer support portion and having a heat insulation in which creep occurs when a load is applied. An initial height of an upper surface of the inner support portion is set so that, during a service life of the low temperature liquid tank, maximum bending stress applied to the bottom plates due to a difference between a height of the upper surface of the inner support portion and a height of an upper surface of the outer support portion remains equal to or smaller than an allowable bending stress of the bottom plates.