Submarine Duct Cable Installation Using Exit-Port Suction
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Solution Overview
Problem
Existing methods for installing elongated elements, such as cables or fibers, into submarine ducts require high entry pressures, which can lead to buckling issues due to the need for propelling fluids to generate drag forces along the full length, especially in long distances, making it difficult to introduce the elements without damaging equipment.
Innovation Solution
A method involving an immerged suction pump at the exit port to create a suction pressure drop that is lower than the hydrostatic pressure, allowing the elongated element to be easily introduced into the duct without a pressure chamber, by applying a pressure drop at the exit port, thus reducing the required entry pressure and preventing cavitation or void generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If propelling fluid is introduced into the duct under high pressure to generate drag forces along the full length of the elongated element, then the elongated element can be propelled into the duct, but the required entry pressure becomes excessively high (tens or hundreds of bar) for very long distances, causing the elongated element to buckle and making installation impossible
Solution Approach 1:
Instead of applying pressure at the entry port to propel the elongated element forward, the invention applies suction (negative pressure) at the exit port to pull the element through the duct. This inversion of the pressure application location allows the elongated element to be installed without experiencing the buckling forces that occur when high entry pressure is applied, while still achieving the necessary propelling force through the fluid drag generated by the suction flow.
2Ease of operation
If high entry pressure is applied to propel the elongated element into the duct, then installation can be achieved, but the elongated element cannot be pushed into the pressure chamber without buckling
Solution Approach 1:
The invention inverts the conventional approach by applying suction at the exit port rather than pressure at the entry port. This allows the elongated element to be gently introduced into the entry port without buckling, as the suction force is applied gradually through the fluid medium rather than as a direct compressive force on the element.
Solution Approach 2:
The propelling fluid acts as an intermediary between the suction pump and the elongated element. The suction pump creates a pressure drop in the fluid, which generates drag forces on the element through fluid-structure interaction. This intermediary fluid transmission allows force application without direct mechanical contact that would cause buckling.
3Force
If suction pressure drop applied by the immerged suction pump is greater than hydrostatic pressure at the exit port location, then stronger propelling force can be generated, but bubbles or voids are generated inside the duct
Solution Approach 1:
The invention carefully controls the suction pressure drop parameter to remain below the hydrostatic pressure threshold. This parameter optimization ensures that the pressure inside the duct remains positive throughout the installation process, preventing cavitation and bubble formation, while still generating sufficient propelling force through the controlled pressure gradient in the propelling fluid.
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 the installation of elongated elements into submarine ducts of varying lengths and depths with reduced pressure requirements, avoiding buckling and equipment damage, while maintaining a positive pressure inside the duct to prevent bubbles or voids, allowing for simpler and more efficient installation processes.
Implementation Method 1
the immerged suction pump being operated at a predetermined suction pressure drop of propelling liquid between the immerged suction pump inlet and the immerged suction pump outlet
Implementation Method 2
make use of a propelling fluid, to generate drag forces along all the length of the elongated element
Implementation Method 3
the predetermined suction pressure drop applied to propelling liquid is smaller than a hydrostatic pressure outside the duct at the location of the immerged suction pump
Data Source
AI summary
Method for installing an elongated element, in a submarine duct, the submarine duct having an entry port and an exit port located in outer liquid (OL) at a second depth,the method comprising the steps of:introducing the elongated element into the entry port,introducing propelling liquid (PL) into the entry port,characterized in that the method comprises a step of sucking propelling liquid (PL) out of the exit port of the duct with an immerged suction pump being operated at a predetermined suction pressure drop (ΔPpump) of propelling liquid (PL) so that the predetermined suction pressure drop (ΔPpump) applied to propelling liquid (PL) is smaller than a hydrostatic pressure (Phydro) of the outer liquid (OL) at the second depth.