Subsea Riser Induction Heating for Wax and Hydrate Control
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Solution Overview
Problem
Hydrocarbons transported in subsea pipelines and risers can solidify at low temperatures due to cooling by seawater, leading to issues like hydrate and wax formation, and existing heating systems often require separate configurations for risers and pipelines, with potential corrosion and inefficiencies in power supply.
Innovation Solution
A riser heating system using alternating currents in riser cables for induction heating and direct electric heating of the pipeline, with adjustable frequency and cable positioning to optimize heating based on temperature and environmental conditions, allowing simultaneous power supply to subsea loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate DEH systems are provided for riser and pipeline, then heating coverage is complete, but device complexity increases
Solution Approach 1:
The patent combines the riser heating system and pipeline heating system into a single integrated DEH system. The power supply unit provides electric current that flows through both the riser and pipeline sequentially, eliminating the need for separate heating systems while maintaining complete heating coverage for both components.
Solution Approach 2:
The integrated heating system performs multiple functions: it heats the riser during hydrocarbon transport and can also heat the pipeline when idle. The single power supply and control system serve dual purposes, making the system more versatile and reducing overall complexity despite the multi-functional requirement.
2Productivity
If electric current is guided through steel pipeline for direct electric heating, then heating efficiency improves, but corrosion risk increases
Solution Approach 1:
The patent introduces an intermediary layer or protective coating on the steel pipeline surface before applying the electric current for direct electric heating. This intermediary layer allows efficient heat transfer while protecting the steel from direct exposure to corrosive effects of the electric current and seawater environment.
Solution Approach 2:
The system incorporates corrosion protection measures that are self-regulating or self-healing. For example, the heating system can detect and respond to corrosion-prone areas by adjusting current distribution, or the protective coating is designed to self-repair minor damages, thereby maintaining heating efficiency while continuously protecting against corrosion.
3Device complexity
If heating system is designed for riser only, then system simplicity is maintained, but heating coverage is insufficient
Solution Approach 1:
The heating system is designed with dynamic switching capability that allows it to adapt between different operational modes. When the riser is in use, the system dynamically switches to heat the riser; when the riser is idle, it dynamically switches to heat the pipeline. This dynamic adaptability maintains system simplicity while ensuring comprehensive heating coverage as needed.
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 adjusts heating power to meet varying temperature needs along the riser and pipeline, reducing corrosion risk and enhancing efficiency by integrating induction and direct electric heating methods.
Implementation Method 1
The heat is generated in the riser steel pipe is due to the varying magnetic fields generated by the alternating currents in the riser cables.
Implementation Method 2
power supply configured to supply electric alternating currents in the first and second riser cables, thereby inducing heat in the riser steel pipe
Implementation Method 3
the same current will heat the pipeline with direct electric heating
Data Source
Figure 1
Figure 2~5
Figure 6~7
AI summary
A riser heating system arranged for heating a hydrocarbon-conducting riser (1) that comprises a riser steel pipe (2) and that extends from a surface structure (5) towards the seabed (3). The system comprises an electric power supply (13) comprising a first output line (15a) and a second output line (15b), a first riser cable (17n, 17a) connected to the first output line (15a) and a second riser cable (17b) connected to the second output line (15b). The first and second riser cables (17n, 17a, 17b) extend along the riser steel pipe (2). The power supply (13) is configured to supply electric alternating currents in the first and second riser cables (17n, 17a, 17b), thereby inducing heat in the riser steel pipe (2).