Subsea Riser Backflushing Valve for Slurry Flow Restoration

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Solution Overview

Problem

Subsea mining operations face costly downtime due to clogging and reduced flow in riser transfer pipes caused by large or irregularly shaped particles and adhesion of material in the slurry during the transfer of material from the sea floor to the surface vessel.

Innovation Solution

A subsea slurry lift pump system with a riser transfer pipe and backflush valve that uses seawater to clear blockages by selectively allowing fluid communication between the slurry inlet line and seawater supply line, enabling backflushing of the riser transfer pipe to restore flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If material is pumped through the riser transfer pipe during subsea mining operations, then material can be transferred from the sea floor to the surface vessel, but the riser transfer pipe can become clogged by large or irregularly shaped particles and adhesion of material

Engineering Contradiction:

Improvematerial transfer capabilityVSAvoidriser transfer pipe flow continuity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The backflush valve is pre-positioned and connected to the seawater supply line, allowing rapid initiation of backflushing operations when clogging is detected. The system prepares the backflushing capability in advance rather than requiring assembly or activation during emergency situations, enabling quick response to maintain flow continuity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Seawater acts as an intermediary flushing medium that is introduced through the backflush valve to clear blockages in the riser transfer pipe. The seawater temporarily displaces and washes away the clogging material, restoring flow without requiring physical intervention or system disassembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the riser transfer pipe becomes clogged, then material flow is reduced or stopped, but clearing the pipe requires costly downtime and operational interruption

Engineering Contradiction:

Improveriser transfer pipe flow continuityVSAvoidoperational downtime for pipe clearing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs self-clearing of the riser transfer pipe through the backflush valve mechanism. When clogging occurs, the system can autonomously initiate backflushing by opening the backflush valve and introducing seawater to clear the blockage, eliminating the need for external intervention or manual clearing operations that would cause extended downtime.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The backflush valve enables continuous operation by allowing rapid clearing of blockages without shutting down the material transfer system. The ability to quickly restore flow through backflushing maintains uninterrupted material transfer operations, minimizing operational downtime and keeping the production system continuously active.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If a backflush valve and seawater supply line are added to the pump system, then the riser transfer pipe can be backflushed to clear blockages, but the device complexity increases

Engineering Contradiction:

Improveriser transfer pipe clearabilityVSAvoidpump system component count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The backflush valve utilizes the existing seawater supply infrastructure already present in subsea mining operations. By connecting to the existing seawater supply line that serves other system functions, the backflush capability is achieved without requiring a separate dedicated water source, thereby minimizing the increase in system complexity while adding the valuable pipe clearing function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 system effectively prevents and clears blockages in the riser transfer pipe, ensuring continuous operation by maintaining adequate slurry flow through the use of seawater backflushing, thereby reducing downtime and operational costs.

Implementation Method 1

a backflush valve between the slurry inlet line and the seawater supply line to selectively allow fluid communication between the slurry inlet line and the seawater supply line so that seawater can enter the slurry inlet line and riser transfer pipe to backflush the riser transfer pipe

Methodology Applied

Scientific EffectFluid communication:

Implementation Method 2

a lift pump in communication with the riser and the subsea production tool to pump the material collected on the sea floor to the vessel via the riser

Methodology Applied

Scientific EffectPumping: Pump

Data Source

PatentUS10400421B2Systems and methods for backflushing a riser transfer pipe

Publication Date: 2019.09.03 HYDRIL USA DISTRIBUTION LLC

AI summary

A method of pumping material from a sea floor to a vessel on a sea surface, including the steps of collecting material from the sea floor using a production tool, connecting the production tool to the vessel with a riser including a riser transfer pipe, and pumping the material from the production tool to the vessel using a subsea slurry lift pump positioned between the production tool and the vessel and attached to the production tool by the riser transfer pipe. The method further includes backflushing the riser transfer pipe by running seawater through the slurry lift pump into the riser transfer pipe toward the production tool.