Seafloor Mining Riser Dynamics and Weather Disconnection
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Solution Overview
Problem
Existing seafloor mining systems are impractical in areas with large wave height fluctuations and cyclonic weather due to riser sensitivity and dynamic loading issues, particularly in transferring ore from mining support vessels to barges.
Innovation Solution
A system featuring a dynamically suspended subsea pump with a vertical riser anchored to the seafloor, using air to lift ore through the riser, and a flexible link hose for connecting the mining machine to the transport vessel, allowing for quick disconnection during adverse weather and relocation of the mining equipment, along with an air lift system as an alternative for ore transportation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vertically suspended riser is used to transport ore from the seafloor to the surface vessel, then ore transportation is enabled, but the system becomes sensitive to wave height fluctuations and cyclonic weather causing high dynamic loading
Solution Approach 1:
The riser is designed as a dynamically suspended system that can move and adapt to wave motions rather than being rigidly fixed. The system allows controlled movement at the surface connection point, enabling the riser to absorb and dissipate wave-induced stresses through dynamic response rather than static resistance, thereby reducing peak dynamic loading while maintaining operational reliability
Solution Approach 2:
The system changes operational parameters by allowing the riser configuration to vary with sea conditions. During adverse weather, the surface connection geometry and tension parameters are adjusted to optimize stress distribution, transforming the riser from a rigid structural element to an adaptable component that maintains functionality across varying seastates
2Productivity
If ore transfer between mining support vessel and barge is performed offshore, then ore can be transported to processing facilities, but the transfer operation becomes infeasible during large wave height fluctuations
Solution Approach 1:
The ore transfer operation is extracted from the offshore environment and performed onshore at a processing facility. The direct vertical riser connection delivers ore continuously to the vessel, eliminating the need for separate transfer operations between offshore vessels that would be disrupted by wave height fluctuations, thereby maintaining productivity while improving adaptability to adverse weather
Solution Approach 2:
The vertical riser system acts as an intermediary that directly connects the seafloor mining operation to the surface vessel, enabling continuous ore delivery without requiring intermediate transfer operations. This eliminates the vulnerable offshore-to-barge transfer step that would be infeasible during large waves, as the riser system itself is designed to accommodate such conditions
3Duration of action of moving object
If the mining system operates continuously in cyclone-prone locations, then production time increases, but the system experiences excessive dynamic loading and potential failure
Solution Approach 1:
The system operates in periodic cycles, alternating between active mining operations during benign weather and maintenance/repositioning phases during adverse weather events. This periodic operation pattern allows the system to accumulate production time over extended periods while avoiding excessive dynamic loading by shutting down or adjusting operations during cyclonic conditions, thereby preserving structural integrity
Solution Approach 2:
The system incorporates pre-positioning and preparatory measures before adverse weather arrives, such as securing the riser system, adjusting tension, and preparing for potential shutdown. These beforehand cushioning actions reduce the impact of extreme weather events on structural integrity, enabling the system to withstand or recover from cyclonic conditions while maintaining overall operational duration
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
Enables efficient ore extraction and transportation in challenging seastates by reducing dynamic loading, increasing production time, and eliminating the need for offshore ore transfer between vessels, while maintaining system integrity during storms.
Implementation Method 1
A lifting system may be in the form of a subsea pump. The subsea pump is normally located adjacent a bottom of the vertical riser.
Implementation Method 2
An alternative lifting system may use air to lift the ore through the vertical riser. The air may be pumped into the vertical riser.
Data Source
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AI summary
A system for seafloor mining comprising a vertical riser anchored to the seafloor; a mining machine to deliver seafloor ore to the vertical riser; a lifting system to pass the ore through the vertical riser; and a transport vessel removably connected to the vertical riser to receive ore from the vertical riser.