LNG Tank Sloshing Damping via Liquid-Filled Ball and Electromagnetic Dissipation
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Solution Overview
Problem
Existing solutions for reducing sloshing in large LNG storage tanks, such as base isolation, can increase sloshing wave height and aggravate liquid surface sloshing, compromising the safety of the storage tank structure.
Innovation Solution
A rebound composite electromagnetic energy dissipation device is installed inside the LNG storage tank, featuring a liquid-filled ball, steel strand, sealed support shell, gas spring, ball screws, horizontal pistons, and a vertical piston. This device utilizes the liquid-filled ball as a tuned liquid damper, with the steel strand, gas spring, and pistons working together to dissipate energy and reduce sloshing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base isolation is adopted to reduce seismic response of the storage tank structure, then the seismic response of the storage tank structure is reduced, but the sloshing wave height of the liquid is increased and the sloshing of the liquid surface is aggravated
Solution Approach 1:
The device segments the sloshing control function into two independent parts: base isolation for structural seismic response reduction, and the electromagnetic energy dissipation device with liquid-filled ball for sloshing wave height control. This segmentation allows each subsystem to optimize its function without interfering with the other, resolving the contradiction between structural safety and sloshing control.
Solution Approach 2:
The liquid-filled ball acts as an intermediary element that couples the structural motion with the liquid sloshing. It transfers and dissipates the energy from both the structural seismic motion and the liquid sloshing motion through electromagnetic damping, preventing the aggravation of sloshing that occurs with base isolation alone.
2Strength
If base isolation is used to protect the storage tank structure during earthquakes, then the structural safety is improved, but the liquid sloshing amplitude increases causing damage to pipe joints and accessories
Solution Approach 1:
The device converts the harmful liquid sloshing motion into beneficial energy dissipation. The liquid-filled ball moves with the sloshing liquid, and this motion is converted into electromagnetic energy dissipation through the damping mechanism, transforming the harmful sloshing energy into heat and other forms of dissipated energy, thereby reducing the sloshing amplitude and protecting pipe joints and accessories.
Solution Approach 2:
The invention replaces traditional mechanical damping mechanisms with an electromagnetic energy dissipation system. The liquid-filled ball coupled with electromagnetic damping provides a non-contact, wear-free, and highly efficient energy dissipation mechanism that effectively controls liquid sloshing amplitude without the limitations of mechanical friction and contact wear.
3Reliability
If a device is designed to reduce liquid sloshing wave height, then the safety of the storage tank structure is ensured, but the device complexity increases
Solution Approach 1:
The liquid-filled ball serves multiple functions simultaneously: it acts as a tuned liquid damper for sloshing control, a mass for electromagnetic coupling, and an energy dissipation element. This multi-functionality reduces the need for separate components, thereby simplifying the overall device structure while maintaining effective sloshing reduction capabilities.
Solution Approach 2:
The device utilizes parameter changes in the liquid-filled ball system, such as varying the ball mass, filling ratio, and electromagnetic damping coefficients, to optimize sloshing control performance. By adjusting these parameters, the device can be tuned to different sloshing conditions without requiring fundamental structural changes, thereby maintaining simplicity while ensuring safety.
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 device significantly reduces the liquid sloshing amplitude, thereby weakening the influence of liquid sloshing caused by earthquakes on the storage tank structure, enhancing the safety and integrity of the tank.
Implementation Method 1
The liquid-filled ball 1 is a sealed hollow ball filled with damping fluid, and the damping fluid should be a fluid with a lower density than the LNG stored liquid, occupying half the volume of the ball, so that the ball can float on the liquid surface of the LNG storage tank.
Implementation Method 2
The gas spring 4 is used for preventing the vertical piston 7 from leaving the vertical slideway to ensure normal operation of the device and provide an elastic restoring force for the liquid-filled ball 1.
Implementation Method 3
The ball screws 5 are located in the vertical slideway, the upper ends of the ball screws 5 are fixed on the lower bottom surface of the vertical piston 7, and the lower ends are fixed on the inner side of the bottom surface of the sealed support shell 3.
Implementation Method 4
A rebound composite electromagnetic energy dissipation device for reducing sloshing with a liquid-filled ball for a large LNG storage tank
Data Source
AI summary
The present invention relates to a rebound composite electromagnetic energy dissipation device for reducing sloshing with a liquid-filled ball for a large liquefied natural gas (LNG) storage tank. When the liquid surface sloshes around, the gas spring is pulled by the steel strand to produce vertical displacement and provide a restoring force, and the vertical displacement of the gas spring drives the fan blades on the sleeves of the ball screws at the bottom to rotate in the damping fluid, consuming energy. The present invention uses hydraulic transmission instead of mechanical transmission of traditional piston motion, and the horizontal pistons produce horizontal displacement in the case of pressure unbalance, thus increasing the flexibility of horizontal piston motion; magnets are arranged in the horizontal slideways and the horizontal pistons to intensify the motion of the horizontal pistons and the relative motion between the horizontal pistons and the interior.