Liquefied Gas Tank Insulation Structure for Thermal Stress and Sloshing
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Solution Overview
Problem
Existing liquefied gas storage tanks face challenges in minimizing thermal stress and pressure stress due to low temperatures and sloshing, while maintaining mechanical strength and thermal insulation, particularly in the secondary insulating wall.
Innovation Solution
The design optimizes the cross-sectional shape of the primary barrier with varying curvature radii and thicknesses for the primary and secondary insulating walls, using a mixed metal and non-metal secondary barrier, and incorporates an auxiliary barrier to connect adjacent main barriers, ensuring the primary insulating wall thickness is similar to the secondary, enhancing thermal insulation and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the primary insulating wall is increased to reduce thermal stress, then thermal insulation performance is improved, but the mechanical strength and resistance to sloshing loads are compromised
Solution Approach 1:
The patent employs a composite insulating wall structure combining multiple materials with different properties: rigid insulating material (for thermal insulation), flexible insulating material (for stress absorption), and reinforcement elements (for mechanical strength). This composite approach allows the wall to simultaneously achieve thermal insulation performance and mechanical strength, resolving the contradiction between thickness-based thermal stress reduction and sloshing load resistance.
Solution Approach 2:
The patent applies different material properties to different regions of the insulating wall based on local stress distribution. The rigid insulating material is positioned in regions requiring thermal insulation, while flexible insulating material and reinforcement elements are strategically placed in areas subjected to high mechanical stress from sloshing. This localized optimization allows the wall to achieve both thermal and mechanical performance without uniformly increasing thickness.
2Strength
If the thickness of the secondary insulating wall is increased to maintain mechanical strength, then structural integrity is improved, but the thermal insulation performance and reduction of low-temperature burden are compromised
Solution Approach 1:
The secondary insulating wall uses a composite structure with rigid insulating material providing thermal insulation and flexible insulating material providing mechanical compliance. The flexible material absorbs thermal contraction stresses while the rigid material maintains insulation performance, allowing the wall to achieve both mechanical strength and thermal insulation without excessive thickness.
Solution Approach 2:
The patent optimizes the thickness parameters of different insulating wall layers based on their specific functions. The primary insulating wall has greater thickness for thermal insulation, while the secondary insulating wall has optimized thickness for mechanical strength and thermal insulation balance. This parameter optimization resolves the contradiction by assigning different thickness requirements to different functional layers.
3Temperature
If the cross-sectional shape of the primary barrier is optimized to minimize thermal stress, then thermal insulation is improved, but the complexity of manufacturing and installation is increased
Solution Approach 1:
The primary barrier is divided into multiple segments with standardized cross-sectional shapes. Each segment can be manufactured independently using standard moldings, then assembled together to form the complete barrier structure. This segmentation maintains the optimized cross-sectional shape for thermal stress reduction while simplifying manufacturing and installation through modular assembly.
Solution Approach 2:
The patent employs curved cross-sectional shapes in the primary barrier design, particularly in the curved portion mentioned in the technical problem. These curved geometries distribute thermal stress more evenly compared to sharp corners, reducing stress concentration. The curved shapes are achieved through standardized moldings that can be easily manufactured and assembled, balancing thermal stress reduction with manufacturing feasibility.
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 minimizes thermal and pressure stresses, maintains mechanical strength, prevents brittle fracture, and improves thermal insulation performance, reducing man-hours in installation by using a non-adhesive elastic material and cleat structure for fixing the secondary insulating wall.
Implementation Method 1
a primary insulating wall in which a primary plywood and a primary insulating material are sequentially disposed to the outside of the primary barrier; a secondary barrier provided on the outside of the primary insulating wall; and a secondary insulating wall in which a secondary insulating material and a secondary plywood are sequentially disposed in a stack to the outside of the secondary barrier
Data Source
AI summary
The present disclosure relates to a liquefied gas storage tank and a ship including the same. A liquefied gas storage tank according to the present disclosure is a liquefied gas storage tank for storing a cryogenic material and includes a primary barrier made of metal to form an accommodating space for accommodating a cryogenic material; a primary insulating wall in which a primary plywood and a primary insulating material are sequentially disposed to the outside of the primary barrier; a secondary barrier provided on the outside of the primary insulating wall; and a secondary insulating wall in which a secondary insulating material and a secondary plywood are sequentially disposed in a stack to the outside of the secondary barrier, wherein the secondary barrier includes a main barrier provided on top of each secondary insulating wall constituting a unit element; and an auxiliary barrier connecting the adjacent main barriers to each other, the secondary barrier is formed of a mixed material of a metal and a non-metal, and the primary insulating wall has a thickness of 66% to 166% of that of the secondary insulating wall in order to lower a thermal stress.