Pipe-in-Pipe Electrical Heating for Hydrocarbon Flow Assurance
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Solution Overview
Problem
Existing "pipe-in-pipe" systems for conveying hydrocarbons face challenges such as heat loss, mechanical complexity, and contamination-induced inefficiencies, particularly in marginal underwater reservoirs with long distances, high depths, and low temperatures, which can lead to pipeline clogging and reduced efficiency.
Innovation Solution
A system with a first pipeline, a second pipeline inside the first with an annular gap, an electrically conductive layer in the gap, an insulating layer, and a power source to apply an electrical potential difference, ensuring efficient heat transfer to the fluid while minimizing environmental losses and tolerance to contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If electrical cables are laid on the external surface of an internal pipeline coaxially arranged within an external pipeline for electrical traced heating, then thermal efficiency is improved, but mechanical complexity and installation costs increase
Solution Approach 1:
The patent merges the electrical heating function directly into the pipeline structure by making the external pipeline itself electrically conductive and using it as the heating element. This eliminates the need for separate electrical cables while maintaining effective heat transfer to the fluid, thus reducing mechanical complexity while preserving thermal efficiency.
2Device complexity
If direct electrical heating with open loop is used where current passes through conveying pipeline and cable, then mechanical simplicity is improved, but current losses increase due to galvanic contact with body of water
Solution Approach 1:
The patent extracts the cable component from the heating system and eliminates the galvanic contact path by having the current pass solely through the conveying pipeline itself. This removes the source of current losses while maintaining mechanical simplicity, as the pipeline serves dual purposes: fluid conveyance and electrical heating.
3Loss of energy
If pipe-in-pipe system with thermal insulation is used, then heat loss is reduced, but mechanical complexity and installation costs increase
Solution Approach 1:
The patent makes the external pipeline serve multiple functions: it acts as both the structural containment element and the electrical heating element. By applying electrical potential directly to this multi-functional pipeline, the system achieves effective heating without requiring separate insulation layers or additional heating components, thus reducing mechanical complexity while managing heat loss.
4Stability of the object's composition
If active heating system is used to maintain fluid temperature, then fluid thermodynamic range is maintained, but system complexity and energy consumption increase
Solution Approach 1:
The patent implements a self-service heating system where the conveying pipeline itself generates the heat needed to maintain fluid temperature. By passing electrical current through the pipeline, the system uses the pipeline's own structure to provide heating, eliminating the need for external heating devices, control systems, or additional energy infrastructure, thus reducing overall system complexity.
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 enhances thermal efficiency by directing heat generated by Joule effect primarily to the fluid-conveying pipeline, reduces mechanical complexity, and maintains system integrity despite contaminants, thus optimizing energy balance and operational reliability.
Implementation Method 1
the electrical current flowing through the electrically conductive layer and/or second pipeline generates heat by Joule effect
Implementation Method 2
The term 'active heating' indicates the systems that supply energy to the fluid, thus differentiating themselves from the passive systems that merely store energy inside the pipelines through thermal insulation
Data Source
AI summary
A system to convey a fluid, in particular a fluid containing hydrocarbons, has a first pipeline, which is made of an electrically conductive material and has an internal diameter; a second pipeline, which is made of an electrically conductive material, has an external diameter smaller than the internal diameter, and is placed inside the first pipeline at a distance from the first pipeline so as to form an annular gap between the first and second pipeline; an electrically conductive layer placed in the annular gap at a distance from the first pipeline; an electrically insulating layer placed between the second pipeline and the electrically conductive layer; and a power source to apply an electrical potential difference between the second pipeline and the electrically conductive layer.