Conductive Plastic Layer for Flexible Pipe Temperature Control
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Solution Overview
Problem
Conventional flexible pipes face challenges in maintaining uniform temperature control and preventing precipitation of waxes and hydrates in crude oil at low temperatures, particularly in offshore applications, due to complex designs and heat loss issues.
Innovation Solution
A flexible pipe with a multilayer structure comprising an interior lining, inner and outer reinforcement layers, and a molded electrically conductive plastic layer, where the conductive layer is in contact with both reinforcement layers and can be heated by an electrical current, allowing targeted heating of specific sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If electrically conductive cables are used for heating the pipe (as described in WO 91/18231), then the pipe can be heated to prevent precipitation of waxes and hydrates, but the design becomes complicated and temperature control becomes irregular
Solution Approach 1:
The patent combines the heating function with the existing reinforcement layers by making them electrically conductive. The reinforcement layers, which are already structurally necessary, are modified to serve dual purposes: mechanical reinforcement and electrical heating. This eliminates the need for separate heating cables or elements, thereby simplifying the overall design while achieving uniform temperature control along the pipe length.
Solution Approach 2:
The reinforcement layers are designed to perform multiple functions simultaneously: providing mechanical strength and stability, and generating heat through electrical conduction. By integrating the heating function into the existing structural components, the patent reduces system complexity and avoids the need for additional dedicated heating elements.
2Temperature
If thermal insulation layers are added to prevent heat loss, then temperature stabilization is improved, but the pipe structure becomes more complex and less flexible
Solution Approach 1:
The heating system is designed to be self-regulating through the PTC effect. When the pipe reaches the desired temperature, the electrical resistance of the conductive plastic increases automatically, reducing the current and heat generation. This eliminates the need for complex external temperature control systems, sensors, and regulation mechanisms, thereby maintaining simplicity while achieving effective temperature stabilization.
3Reliability
If the pipe is heated to prevent precipitation of waxes and hydrates, then the transport function is maintained, but energy consumption increases
Solution Approach 1:
The PTC effect provides inherent feedback control: as the pipe temperature increases, the electrical resistance of the conductive plastic layer increases, automatically reducing the heating power. This negative feedback mechanism ensures that energy input is dynamically adjusted to match the actual heating needs, preventing excessive energy consumption while maintaining reliable transport function.
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 solution enables efficient and uniform heating of the pipe, preventing precipitation and thermal degradation, while maintaining mechanical stability and flexibility, without significant cost increases or complex designs.
Implementation Method 1
the molded electrical conductive plastic layer... can be heated by an electrical current
Data Source
AI summary
A flexible pipe of multilayer structure which comprises the following layers, from the inside to the outside: an interior lining; an inner reinforcement layer; a layer of molded electrically conductive plastic; an outer reinforcement layer; and an exterior sheath. The electrically conductive plastic layer is in electrical contact with the two reinforcement layers, and the two reinforcement layers can be connected to a source of electrical current. It is thus possible to achieve efficient heating of the pipe, and it can therefore be used for conveying oil in cold regions.