Ship Tank Mounting with Insulated Saddle for Thermal Stress Reduction
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Solution Overview
Problem
Existing designs for storing liquid gas, particularly cryogenic LNG, in ships face challenges with thermal stresses due to the high coefficient of thermal expansion of tank materials and the inefficient use of ship space, especially in bilobe tanks where thermal stresses arise at the highest point of the saddle, limiting their effectiveness at low temperatures.
Innovation Solution
A bi-top pressure tank design with a separated foundation and saddle, featuring a flat thermal insulating layer that allows relative movement in all directions, and strategically placed webs to absorb and distribute forces, ensuring the tank's stability and minimizing thermal stresses without relying on the ship's hull for support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a common saddle design for both tank halves is used in bilobe tanks, then the tank can be stored in the ship, but thermal stresses arise at the highest point of the saddle due to thermal shrinkage occurring towards the center of the saddle
Solution Approach 1:
The patent divides the tank into two separate halves, each with its own independent foundation and saddle system. This segmentation allows each half to independently accommodate thermal shrinkage without generating significant thermal stresses, while still maintaining overall tank stability through the connection between halves.
2Device complexity
If the foundation and saddle form a single structural unit, then the structure is simplified, but thermal stresses cannot be compensated in all directions including transverse to the longitudinal direction
Solution Approach 1:
The foundation and saddle are divided into separate components rather than forming a single structural unit. This allows independent movement and stress compensation in multiple directions, particularly enabling transverse thermal shrinkage compensation while maintaining longitudinal stability.
3Device complexity
If circular cylindrical tanks are used, then the tank structure is simple, but the ship space is not used as efficiently as with bilobe tanks
Solution Approach 1:
The patent employs bilobe tank geometry with curved surfaces that more efficiently conform to the ship's hull shape and utilize available space. The curved design allows better space utilization compared to circular cylindrical tanks while maintaining structural integrity through the segmented foundation and saddle system.
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 effectively reduces thermal stresses across all directions, ensuring the stability and safety of cryogenic liquid gas storage in bilobe tanks, particularly for LNG, by using pressure-resistant and shear-resistant insulating materials like compressed wood, allowing for efficient use of ship space and maintaining the ship's trim during temperature changes.
Implementation Method 1
the insulating layer is arranged between the saddle and the tank
Implementation Method 2
due to the temperatures themselves and also due to the higher thermal expansion coefficient of the tank material
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Disclosed is a device for mounting a tank in a ship (1). Said device comprises at least two foundations (4) which are fastened to the hull at a distance from each other in the longitudinal or transversal direction of the ship (1) and each of which supports one saddle (6) that is adapted to the shape of the tank (3) and is used for accommodating the tank (3). The inventive device further comprises an insulating layer (8) that is provided on each saddle (6) to thermally insulate the foundations (4) relative to the tank (3) as well as safety mechanisms (10; 12; 15) for mounting the tank (3) on the foundations (4), said safety mechanisms (10; 12; 15) allowing a relative movement between the tank (3) and at least one foundation (4) on the insulating layer (8) in the longitudinal direction of the tank. Each saddle (6) is fastened directly to the tank (3) and has a planar bottom face (7) while each foundation (4) has a planar top face (5), all bottom and top faces (7; 5) being parallel to one another. The insulating layer (8) is disposed between the bottom face (7) of the saddle (6) and the top face (5) of the associated foundation (4) while the safety mechanisms (10; 12; 15) allow a limited relative movement between each saddle (6) and the foundation (4) thereof on or in the insulating layer (8).