LNG Tank Loading Tower Pump Alignment for Sloshing Resistance
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Solution Overview
Problem
Existing LNG storage tanks on ships face mechanical strength issues due to sloshing phenomena, particularly when liquefied gas is used as fuel, as the filling level varies and equipment is subjected to significant forces, leading to inadequate performance of conventional loading/unloading towers.
Innovation Solution
A waterproof and thermally insulating tank design with a loading/unloading tower where the first pump and support foot are aligned transversely to reduce twisting or bending forces, and the pumps are positioned outside a triangular section defined by the masts, with sumps to house suction members, enhancing mechanical strength and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the loading/unloading tower uses a conventional tripod structure with pumps positioned inside the triangular section, then the device complexity is reduced and ease of manufacture is improved, but the mechanical strength and resistance to sloshing forces are insufficient
Solution Approach 1:
The pump is repositioned from inside the triangular section formed by the three masts to outside this section, changing the spatial arrangement dimension. This dimensional repositioning allows the pump to be located in a region less susceptible to sloshing forces while maintaining functional connectivity to the tank, thereby improving mechanical strength without fundamentally altering the tripod structure
Solution Approach 2:
The suction member is positioned in advance within a sump that is integrated into the tank bottom structure. This preliminary positioning ensures that the suction member is already in place to handle sloshing conditions before they occur, allowing the pump to draw liquid even when the tank is partially filled and sloshing forces are present
2Strength
If the pump is positioned inside the triangular section formed by the masts, then the device complexity is reduced, but the mechanical strength against sloshing forces deteriorates
Solution Approach 1:
The pump is relocated from the interior of the triangular section to the exterior, changing its positional dimension. This allows the pump to operate from a location that experiences reduced sloshing forces while maintaining its function through the strategically positioned suction member in the sump
Solution Approach 2:
The suction member acts as an intermediary between the pump (located outside the triangular section) and the liquid in the tank. It transmits the pumping function while being positioned in the sump to handle sloshing conditions, mediating between the pump's operational requirements and the tank's sloshing environment
3Adaptability or versatility
If the tank filling level varies over the entire filling range, then the adaptability to different operational needs is improved, but the mechanical strength against sloshing forces deteriorates
Solution Approach 1:
The suction member is preliminarily positioned in the sump at the bottom of the tank, ensuring it is ready to handle liquid withdrawal regardless of the filling level. This preliminary positioning allows the system to adapt to varying fill levels from heel to full while maintaining pump functionality and reducing sloshing impact
Solution Approach 2:
The sump structure automatically adapts to different filling levels by allowing the suction member to draw liquid from the lowest point of the tank. The system self-adjusts to varying operational conditions without requiring active control, maintaining functionality across the entire filling range while the pump remains positioned outside the triangular section
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a sealed and thermally insulating tank (1) for storing a fluid, the tank being held in a load-bearing structure (3) integrated into a ship, said ship having a longitudinal direction (x), the tank (1) comprising a loading/unloading tower (2) mounted to a ceiling wall (9) of the load-bearing structure (3), and the loading/unloading tower (2) comprising a first, a second and a third vertical mast (11, 12, 13) defining a prism having a triangular cross-section; the loading/unloading tower (2) holds at least a first pump (18, 20); the tank (1) has a support leg (31) which is secured to the load-bearing structure (3); the tank (1) has at least one sump (30), and the first pump (18, 20) is disposed outside the triangular prism and aligned with the support leg (31) in a first transverse plane (P1) which is orthogonal to the longitudinal direction (x) of the ship.