Direct Electric Heating Pipeline Ice Plug Prevention
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Solution Overview
Problem
Direct electric heating for pipelines is excessively expensive and complex, especially for deep or thermally isolated pipelines, where traditional methods for hydrate and ice removal are ineffective due to high costs and equipment demands.
Innovation Solution
A method and system for direct electric heating that heats the pipeline to a temperature above the ice melting point but below the hydrate melting point, using a surface vessel to deliver power through a riser cable and DEO-cables connected to the pipeline, focusing on melting a thin ice layer near the pipeline wall to increase permeability and facilitate chemical injection and depressurization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct electric heating is applied to pipelines at large depth or with high thermal isolation, then hydrate and ice plugs are prevented, but the cost and system complexity become excessively high
Solution Approach 1:
The patent applies local quality by heating only the pipeline wall and adjacent fluid layer rather than the entire pipeline contents. The heating cables are mounted on the pipeline exterior, creating a localized thermal zone that prevents ice plug formation at the wall-fluid interface where it initiates, without requiring heating of the bulk fluid throughout the pipeline.
Solution Approach 2:
The patent employs partial action by providing just enough heating to maintain the pipeline wall and adjacent fluid above the ice formation temperature. This partial heating approach is sufficient to prevent plug formation at the critical wall interface, avoiding the excessive energy consumption and system complexity that would result from heating the entire pipeline volume.
2Productivity
If traditional chemical injection methods are used for deep water pipelines, then hydrate plugs can be removed, but the equipment demands and operational difficulty increase significantly
Solution Approach 1:
The patent applies preliminary action by preventing ice plug formation in the first place through continuous localized heating of the pipeline wall and adjacent fluid. This preventive approach eliminates the need for complex plug removal operations, making the system easier to operate compared to traditional chemical injection methods that require specialized equipment for deep water applications.
3Productivity
If full pipeline heating is applied to melt ice plugs, then flow is restored, but energy consumption and system complexity become excessive
Solution Approach 1:
The patent uses local quality by concentrating heating only at the pipeline wall and adjacent fluid layer where ice formation occurs. This localized heating approach restores flow by preventing ice plug formation at the wall-fluid interface without requiring energy-intensive heating of the entire pipeline contents, thus reducing overall energy consumption.
Solution Approach 2:
The patent extracts the heating function from the bulk pipeline fluid and applies it only to the critical wall-fluid interface zone. This extraction of the heating function to a specific location eliminates the need for full pipeline heating, significantly reducing energy consumption while maintaining flow restoration capability.
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
Significantly reduces costs and complexity by allowing partial ice melting near the pipeline wall, enabling chemical injection and depressurization methods to remove plugs, ensuring pipeline flow and preventing future plug formation during shutdowns.
Implementation Method 1
Direct electric heating (DEO) is based on the fundamental principle that electric current in a metallic conductor generates heat due to ohmic loss
Implementation Method 2
the heating takes place to a temperature above the melting point for ice, but below the melting point for hydrates
Data Source
AI summary
Method and system for direct electric heating of a pipeline to contribute to removal or hindrance of plugs of ice and optionally hydrates, distinguished in that heating takes place to a temperature above the ice melting point, but below the hydrate melting point.