Return Pipe Pressure Control for Deep Sea Mining
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Solution Overview
Problem
Deep sea mining methods face challenges in controlling the return flow of slurry heavier than water, which can lead to vacuum formation and pipe collapse due to unbalanced hydrostatic pressure and friction losses, limiting flexibility and risking structural integrity in return pipes.
Innovation Solution
Implementing a method that generates an upward flow of excavated matter to a processing platform, where it is separated into valuable and non-valuable parts, and then controls the pressure in the return pipe using active and passive means such as restrictors, turbines, and pumps to manage the flow rate and prevent pipe collapse or cavitation, optimizing pipe capacity and energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hydrostatic pressure of the slurry column in the return pipe is higher than the sum of friction losses and water column pressure, then the slurry flows upward, but a high risk of vacuum at the top of the return pipe remains
Solution Approach 1:
A pressure monitoring system continuously measures the pressure at the top of the return pipe and provides feedback to the flow control system. When vacuum conditions are detected (pressure drops below a threshold), the system automatically adjusts the flow rate or activates compensation mechanisms to prevent pipe collapse, creating a closed-loop control system that responds to actual operating conditions.
Solution Approach 2:
The system implements preventive measures by monitoring pressure trends and adjusting operational parameters before vacuum conditions develop. Flow rate is controlled to maintain pressure above critical thresholds, and the system can pre-activate compensation mechanisms when pressure approaches dangerous levels, preventing vacuum formation rather than merely responding to it.
2Reliability
If active pressure control means are added to prevent vacuum and pipe collapse, then pipe integrity is maintained, but device complexity increases
Solution Approach 1:
The pressure control system is designed to operate autonomously using self-service principles. The monitoring system automatically detects pressure changes and triggers control actions without human intervention. The system uses its own operational data to self-regulate, eliminating the need for external control and reducing operational complexity while maintaining reliability.
Solution Approach 2:
The pressure control means are integrated into existing system components rather than being entirely separate additions. The flow control system serves multiple functions: it controls slurry flow rate for production purposes and simultaneously prevents vacuum formation by maintaining minimum pressure. This multi-functionality reduces overall system complexity by combining safety and production control in a single integrated 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 approach enhances the controllability of the return flow, maintains pipe integrity, and allows for flexible operation by actively managing vacuum conditions, particularly in free fall return pipes, thereby ensuring safe and efficient deep sea mining operations.
Implementation Method 1
If the hydrostatic pressure of the slurry column in the return pipe is higher than sum of the friction losses and the water column pressure, than a high risk of vacuum at top of return pipe remains
Implementation Method 2
If the hydrostatic pressure of the slurry column in the return pipe is higher than sum of the friction losses and the water column pressure
Implementation Method 3
controlling the pressure in the return pipe for avoiding collapse of the return pipe and/or cavitation in the return pipe
Data Source
AI summary
A method for deep sea mining includes generating an upward flow of valuable matter in a riser line from the bottom of a body of water to a matter processing platform; processing the matter at the processing platform; generating a return flow in a return pipe of a mixture of seawater and a non-valuable part of the matter from the processing platform towards the bottom of the body of water; and controlling the pressure in the return pipe for avoiding collapse of the return pipe and/or cavitation of the return pipe, in particular for avoiding collapse of or cavitation in an upper part of the return pipe.