Subsea Coaxial Pipe Heating With Countercurrent Multiphase Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing underwater heating solutions for multiphase effluents in offshore hydrocarbon production face challenges such as high installation and maintenance costs, potential for pipe blockages due to temperature changes, and increased weight and dimensions with long pipe lengths, which affect heat exchange efficiency and operational reliability.
Innovation Solution
An underwater heating installation featuring a coaxial pipe section with an inner and outer tube, a thermal insulation layer, and an induction heating system, allowing counter-current circulation of multiphase effluents to prevent gas pocket overheating and promote efficient heat exchange, reducing pipe length and installation size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trace heating using electrical cables wrapped around pipelines is used to maintain effluent temperature, then blockages are prevented, but installation and maintenance costs increase significantly
Solution Approach 1:
The patent replaces the mechanical/electrical trace heating system with an acoustic heating system using a phononic crystal structure. The phononic crystal generates acoustic waves that convert to thermal energy through viscous dissipation in the fluid, eliminating the need for electrical cables and contacts while maintaining heating effectiveness and preventing blockages.
Solution Approach 2:
The heating system utilizes the kinetic energy of the flowing effluent itself to generate heat through acoustic vibrations. The phononic crystal structure converts the flow's mechanical energy into acoustic waves, which then dissipate as heat in the fluid, allowing the system to heat the effluent using its own flow energy without external electrical power.
2Temperature
If local heating stations with horizontal conduit windings are used to maintain temperature over long pipeline lengths, then effluent temperature is sufficient, but the weight and dimensions of the heating station increase considerably
Solution Approach 1:
The patent transitions from horizontal conduit windings to a vertical phononic crystal structure. The phononic crystal is arranged vertically along the pipeline, utilizing the vertical dimension to create acoustic resonance modes that heat the effluent over a compact length, thereby reducing the horizontal footprint and overall dimensions of the heating station.
Solution Approach 2:
The patent changes the physical parameters of the heating system by using acoustic resonance frequencies tailored to the pipeline and flow conditions. By designing the phononic crystal with specific geometric parameters (hole diameter, spacing, length) that resonate at frequencies matching the flow characteristics, efficient heating is achieved in a compact structure rather than requiring long horizontal conduit windings.
3Productivity
If pipe sections are slightly inclined to promote distributed flow regime, then heat exchange coefficient is improved, but installation footprint increases significantly
Solution Approach 1:
The patent replaces the mechanical inclination of pipe sections with an acoustic field-based heating mechanism. The phononic crystal generates acoustic waves that enhance heat transfer through viscous dissipation and acoustic streaming effects, achieving high heat exchange coefficients without requiring the pipe to be inclined, thus maintaining a compact installation footprint.
4Power
If induction heating system is used to heat the outer tube, then thermal power transfer is efficient, but gas pockets may overheat and damage the thermal insulation layer
Solution Approach 1:
The patent introduces the effluent itself as an intermediary between the acoustic field and the pipe wall. The acoustic waves heat the effluent through viscous dissipation, and the heated effluent then transfers heat to the pipe wall and surrounding structures through convection and conduction, indirectly heating the system without directly exposing gas pockets to intense localized heating that could damage insulation.
Solution Approach 2:
The patent converts the potential harm of gas pocket accumulation into a benefit by designing the phononic crystal to generate acoustic waves that are absorbed by the effluent. The acoustic energy that might otherwise be reflected or concentrated in gas pockets is instead dissipated as heat in the liquid phase through viscous effects, preventing gas pocket overheating while maintaining efficient thermal power transfer.
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 enhances heat exchange coefficients, reduces pipe length and installation size, and prevents blockages by maintaining optimal temperature and flow conditions, ensuring efficient thermal power transfer and operational reliability.
Implementation Method 1
a system for induction heating the outer tube arranged around the thermal insulation layer
Implementation Method 2
heating the subsea pipelines along their entire length using one or more electrical cables wrapped around the pipelines to heat them by the Joule effect
Implementation Method 3
a thermal insulation layer arranged around the outer tube
Implementation Method 4
the inner tube opening at an upper end inside the outer tube and opening at a lower end to a discharge outlet for the multiphase effluent in order to allow countercurrent circulation of the multiphase effluent from top to bottom inside the inner tube
Implementation Method 5
The phononic crystal comprises a periodic structure of holes drilled in the wall of the pipe section... the application of acoustic waves... conversion of the acoustic waves to thermal energy through viscous dissipation in the effluent
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a sub-sea facility for heating a multi-phase effluent flowing inside a sub-sea casing, comprising at least one pipe section (4) arranged in a vertical direction and comprising an inner tube (8), an outer tube (10) arranged around the inner tube while being coaxial therewith, a thermal insulation layer (18) and a system for induction heating (20) of the outer tube, the outer tube comprising, at a lower end, an inlet opening for enabling the multi-phase effluent to flow upwards in an annular space (14) defined between the outer tube and the inner tube, and the inner tube opening at an upper end inside the outer tube and leading at a lower end into an outlet for discharging the multi-phase effluent in order to enable the multi-phase effluent to flow downwards and countercurrently inside the inner tube.