Double-Shell Tank Dome Alignment for Liquefied Gas
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Solution Overview
Problem
In double-shell tanks used for transporting and storing liquefied gases, the thermal contraction of the inner shell due to low-temperature gases causes potential thermal stress when the positions of the inner and outer domes and manholes are not properly aligned, leading to the risk of pipe contact and heat ingress.
Innovation Solution
A horizontal type cylindrical double-shell tank design where the inner shell dome is provided with an inner manhole and the outer shell dome with a corresponding outer manhole, with an annular blocking member dividing the vacuum space to restrict dome and manhole positions, preventing thermal stress and allowing for efficient inspection of internal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner shell dome and outer shell dome are fixed at different positions to accommodate pipe penetration, then pipe installation is facilitated, but thermal stress occurs in the inner shell due to thermal contraction
Solution Approach 1:
The patent aligns the inner shell dome and outer shell dome at the same axial position, creating a coaxial arrangement. This positional alignment in the radial dimension allows pipes to penetrate both shells at corresponding points without causing thermal stress, while still facilitating pipe installation through the aligned openings.
Solution Approach 2:
The patent introduces asymmetry in the dome positioning by aligning the inner and outer domes at the same axial location, breaking the conventional symmetric arrangement where domes are positioned independently. This asymmetric alignment resolves the thermal stress issue while maintaining pipe penetration capability.
2Device complexity
If the inner shell dome and outer shell dome are positioned independently to facilitate pipe penetration, then pipe routing is simplified, but the distance between domes changes causing pipe contact
Solution Approach 1:
By aligning the inner and outer domes at the same axial position, the patent creates a consistent radial reference. This allows pipes to be routed through both shells at corresponding angular positions, simplifying pipe routing while maintaining a fixed radial distance that prevents pipe contact.
Solution Approach 2:
The patent creates an equipotential arrangement by positioning the inner and outer domes at the same axial level, establishing a reference plane that ensures consistent spacing. This equipotential positioning prevents differential movement that could cause pipe contact while facilitating straightforward pipe routing.
3Ease of operation
If manholes are positioned away from domes to allow inspection, then internal device inspection is enabled, but heat ingress increases due to larger open areas
Solution Approach 1:
The patent merges the location of the inner shell manhole and outer shell manhole to the same axial position on the domes. This combined positioning allows inspection access while minimizing the total open area exposed to heat, as the manholes are concentrated at one location rather than distributed across larger surface areas.
Solution Approach 2:
The patent applies local quality by positioning manholes specifically on the dome structures rather than on the cylindrical shell portions. This localized placement on the domed surfaces minimizes the heat transfer area while still providing adequate inspection access to internal 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 restricts the positions of the inner and outer domes and manholes without causing thermal stress, enabling efficient inspection and reducing the volume of vacuum space that needs to be re-established, while minimizing heat ingress through the use of thermal-insulating materials and inert gas enclosures.
Implementation Method 1
an outer shell forming a vacuum space as a thermal insulating layer between the inner shell and the outer shell
Implementation Method 2
the outer shell forms a vacuum space as a thermal insulating layer
Implementation Method 3
when the liquefied gas is fed into the inner shell, thermal contraction of the inner shell occurs
Data Source
Figure 1
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AI summary
A horizontal type cylindrical double-shell tank (2) includes an inner shell (3) and an outer shell (4). The inner shell (3) includes an inner shell main part (31) storing a liquefied gas and an inner shell dome (32) protruding from the inner shell main part (31). The outer shell (4) forms a vacuum space (20) between the inner shell (3) and the outer shell (4), and includes an outer shell main part (41) surrounding the inner shell main part (31) and an outer shell dome (42) surrounding the inner shell dome (32). The inner shell dome (32) is provided with an inner shell manhole (30). The outer shell dome (42) is provided with an outer shell manhole (40) at a position corresponding to a position of the inner shell manhole (30).