Sump Structure Fixing Means for Thermal Contraction in Cryogenic Tanks
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Solution Overview
Problem
Fluid storage facilities for liquefied gases face mechanical stress issues due to thermal contraction of sump structures, which can reduce the operational life of the tanks, especially in offshore applications where the sump structure is fixed to the supporting structure.
Innovation Solution
A fluid storage facility design that includes a sump structure with a rigid container and a fixing means allowing relative movement in a transverse direction, preventing excessive mechanical stress by allowing thermal contraction while maintaining fixation to the supporting structure, using features like fixing lugs, anchoring devices, and perforated plates to facilitate movement and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sump structure is fixed rigidly to the supporting structure, then the sump structure is securely anchored, but thermal contraction during cryogenic fluid loading generates excessive mechanical stress that accelerates material fatigue and limits operational life
Solution Approach 1:
The fixing means is designed to allow dynamic relative movement between the sump structure and supporting structure in the transverse direction. This dynamic capability enables the fixing system to accommodate thermal contraction during cryogenic fluid loading while maintaining secure anchoring, thereby preventing excessive mechanical stress and material fatigue.
Solution Approach 2:
The fixing means allows change in the positional parameter between the sump structure and supporting structure. By permitting relative movement up to 5mm in the transverse direction, the system adapts to thermal expansion/contraction parameter changes without generating damaging stress, thus extending operational life while maintaining reliability.
2Duration of action of stationary object
If the sump structure is not fixed to the supporting structure, then thermal contraction stresses are avoided, but the sump structure cannot be properly anchored and fluid movement cannot be controlled in offshore applications
Solution Approach 1:
The fixing means provides a dynamic connection that maintains anchoring reliability while accommodating thermal movement. This dynamic fixation allows the sump structure to remain securely attached to the supporting structure for fluid control purposes, while simultaneously allowing relative movement to prevent thermal stress accumulation.
3Stress or pressure
If the fixing means allows relative movement to accommodate thermal contraction, then mechanical stress is reduced, but the fixing strength may be compromised
Solution Approach 1:
The fixing means employs a dynamic design that reduces mechanical stress through permitted relative movement while maintaining adequate fixing strength. The fixing system is engineered to provide sufficient anchoring force for normal operation and fluid control, while allowing controlled movement during thermal contraction to prevent stress concentration and material fatigue.
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
The solution extends the service life and reliability of the sump structure by accommodating thermal contraction without subjecting the fixing means to excessive mechanical stress, thereby enhancing the operational efficiency and durability of the storage facility.
Implementation Method 1
during the loading of the tank with a cryogenic fluid such as LNG, those elements of the tank directly in contact with the fluid, such as the sump structure, are subject to a strong temperature variation, which has the effect of contracting them thermally
Data Source
AI summary
The invention relates to a fluid storage facility, the storage facility comprising a supporting structure (1) and a tank, the tank having at least one tank bottom wall fixed to the supporting structure (1), wherein the bottom wall has a structure with multiple layers superimposed in a direction of thickness, including at least one sealing membrane and at least one thermal insulation barrier arranged between the sealing membrane and the supporting structure (1),wherein the bottom wall has a sump structure (9) having a rigid container (10, 11) comprising a side wall (12), the container (10, 11) being arranged through the thickness of the bottom wall, and the sump structure (9) comprising at least one fixing means (15) designed to fix the rigid container (11) to the supporting structure (1) at a fixing point,and wherein the at least one fixing means (15) is configured to allow the relative movement of the side wall (12) of the container (11) with respect to the supporting structure (1) in a transverse direction perpendicular to the side wall (12) at the fixing point of the container (11).