Subsea Induction Heating With Counter-Current Flow Against Hydrate Blockage
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Solution Overview
Problem
Subsea hydrocarbon pipelines face issues with temperature-related blockages due to hydrate crystal and solid deposit formation, which existing heating solutions like trace heating and local heating stations are costly and bulky, and require continuous installation.
Innovation Solution
A subsea heating installation featuring a vertical pipeline section with an inner and outer tube, where the effluent circulates from bottom to top in an annular space and then counter-currently inside the inner tube, utilizing induction heating to maintain efficient heat transfer while preventing gas pocket overheating, reducing installation bulk and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If trace heating using electric cables is used to heat subsea pipelines, then the effluents can be maintained at a temperature above the critical threshold, but the installation and maintenance costs are significant and the installation must be continuous along the entire pipeline length
Solution Approach 1:
The heating system is divided into discrete heating stations positioned at specific locations along the pipeline rather than continuous heating cables. Each heating station is a self-contained unit that can be independently installed and maintained, segmenting the overall heating function into manageable sections.
Solution Approach 2:
The patent introduces an intermediary heating mechanism using induction heating coils that generate electromagnetic fields to heat the pipeline externally. This intermediary approach allows heating without direct contact with the effluent, enabling more flexible positioning and reducing the need for continuous installation along the entire pipeline length.
2Power
If local heating stations are used to heat subsea pipelines, then high thermal power can be injected with minimized pipeline length heated, but the weight and dimensions of the heating station increase considerably
Solution Approach 1:
The heating stations are designed to concentrate thermal power injection at specific localized positions along the pipeline where it is most needed. By positioning heating stations at strategic intervals rather than distributing heating continuously, the system achieves high thermal power delivery while minimizing the overall weight and dimensions of the heating infrastructure.
3Power
If the pipeline section is disposed along a substantially vertical direction with counter-current circulation, then heat exchange coefficients are enhanced and thermal power transfer is improved, but the risk of gas pocket overheating increases
Solution Approach 1:
The system employs dynamic control of the induction heating coils to adjust heating intensity based on real-time conditions. By making the heating process dynamic rather than static, the system can respond to changing flow conditions and prevent gas pocket overheating while maintaining enhanced heat exchange coefficients through vertical counter-current circulation.
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 configuration promotes a distributed flow pattern, enhancing heat exchange coefficients and allowing for high thermal power transfer, reducing pipeline length and installation bulk while preventing destructive overheating, thus maintaining efficient effluent circulation and preventing blockages.
Implementation Method 1
a system for heating by induction the outer tube disposed around the thermal insulation layer
Implementation Method 2
a thermal insulation layer disposed around the outer tube
Implementation Method 3
the inner tube opening at an upper end inside the outer tube and emerging at a lower end towards a discharge outlet for the multiphase effluent in order to allow counter-current circulation of the multiphase effluent from top to bottom inside the inner tube
Data Source
AI summary
A subsea installation for heating a multiphase effluent circulating inside a subsea shell, includes at least one pipeline section disposed along a vertical direction and has an inner tube, an outer tube disposed around the inner tube while being coaxial therewith, a thermal insulation layer, and a system for heating by induction the outer tube. The outer tube has at a lower end an intake aperture to allow circulation of the multiphase effluent from bottom to top in an annular space delimited between the outer tube and the inner tube. The inner tube opening is at an upper end inside the outer tube and emerges at a lower end towards a discharge outlet for the multiphase effluent to allow counter-current circulation of the multiphase effluent from top to bottom inside the inner tube.