Cold Flow Reactor Hydrate Management Process
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Solution Overview
Problem
Current flow assurance strategies for subsea hydrocarbon pipelines, such as continuous chemical injection or pipeline heating, are impractical and uneconomic for long pipelines, leading to gradual constriction and pressure drop due to hydrate deposition on pipe walls during the cold flow process.
Innovation Solution
A process involving two cold flow reactors with heat exchangers and static mixers, where one reactor is always operational to form a hydrate slurry while the other is remediated by removing hydrate or hydrocarbon-based solids through chemical introduction or surface heating, and the remediated stream is recycled to prevent blockages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous chemical injection or pipeline heating is used to prevent hydrate and wax formation, then hydrate and wax deposition is prevented, but the cost and practicality become unacceptable for long pipelines
Solution Approach 1:
The pipeline is divided into multiple segments with individual flow assurance systems. Each segment can be independently controlled and maintained, allowing the system to handle long pipeline distances without requiring a single complex continuous intervention system across the entire pipeline length.
Solution Approach 2:
Instead of continuous chemical injection or heating, the system uses periodic pigging operations to clear hydrate and wax deposits. Intermittent maintenance activities are performed on pipeline segments to remove accumulated solids, replacing the need for continuous prevention measures.
2Device complexity
If cold flow process is used to transport hydrocarbons in long subsea pipelines, then chemical injection and heating costs are reduced, but hydrate deposition on pipe walls causes gradual constriction and pressure drop
Solution Approach 1:
The cold flow process operates continuously without chemical injection, but periodic pigging operations are implemented to remove hydrate deposits that accumulate on pipe walls over time. This maintains flow area and pressure characteristics while keeping the system simple.
Solution Approach 2:
Hydrate deposits that form on pipe walls during cold flow are periodically removed using pigs that travel through the pipeline. The removed hydrates are discarded or potentially recovered, preventing gradual constriction of flow area while maintaining the simplicity of the cold flow process.
3Productivity
If hydrates are allowed to form as a flowable slurry in cold flow process, then continuous flow is maintained, but hydrate film deposition on pipe walls and mixer surfaces causes gradual constriction
Solution Approach 1:
The hydrate slurry flows continuously through the pipeline, but periodic pigging operations are used to remove hydrate films that deposit on pipe walls and mixer surfaces. This maintains continuous flow productivity while preventing gradual flow area constriction.
Solution Approach 2:
Pigs serve as intermediary devices that travel through the pipeline to remove hydrate deposits. These mechanical cleaners act as mediators between the flowing hydrate slurry and the pipe walls, preventing the slurry from directly causing constriction through film deposition.
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 approach maintains continuous flow by preventing substantial hydrate and wax deposition, reducing pressure drops, and ensuring the cold flow process's effectiveness in long subsea pipelines.
Implementation Method 1
cooling the portion of the hydrocarbon stream directed to the first cold flow reactor to a temperature less than the hydrate formation temperature
Implementation Method 2
each cold flow reactor comprising a heat exchanger and at least one static mixer
Implementation Method 3
hydrates are removed by introducing chemicals into the lesser portion of the hydrocarbon stream
Implementation Method 4
hydrates are removed by heating the external surfaces of the second cold flow reactor
Data Source
AI summary
A process for managing hydrates and hydrocarbon-based solids in a hydrocarbon stream. The process includes: introducing the hydrocarbon stream into an inlet of a system comprising at least a first cold flow reactor and a second cold flow reactor, each cold flow reactor comprising a heat exchanger and at least one static mixer; directing at least a portion of the hydrocarbon stream to the first cold flow reactor; cooling the portion of the hydrocarbon stream directed to the first cold flow reactor to a temperature less than the hydrate formation temperature, the temperature effective to substantially complete hydrate formation upon exiting the system to form a hydrate and hydrocarbon-based solids managed hydrocarbon stream; directing a lesser portion of the hydrocarbon stream to the second cold flow reactor; and remediating the second cold flow reactor by removing hydrate or hydrocarbon-based solids formed on internal surfaces of the second cold flow reactor. A remediable system for managing hydrates and hydrocarbon-based solids in a hydrocarbon stream is also described.