Slug Catcher Surge Management via Segmented Vessel Design

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Solution Overview

Problem

Natural gas pipelines often experience surges due to pipeline pig operations, leading to large liquid and solid deposits in slug catchers, which can disrupt downstream equipment and processes, causing shutdowns and inefficiencies in gas and liquid hydrocarbon processing.

Innovation Solution

A method involving a slug catcher that separates gaseous hydrocarbons from liquids and solids, with a portion of the mixture directed to a separation vessel and, during surges, an additional portion sent to a surge vessel, allowing for uninterrupted supply of hydrocarbons and liquids to downstream processes, enabling smaller slug catcher designs and reduced operational costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the slug catcher is sized to receive large volumes of liquids and solids during pigging operations, then it can handle surge conditions, but it becomes much larger and more expensive

Engineering Contradiction:

Improveability to handle surge conditionsVSAvoidslug catcher volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The system is divided into two separate vessels: a slug catcher for normal operation and a surge vessel for surge conditions. This segmentation allows each vessel to be optimally sized for its specific function, avoiding the need for the slug catcher to be oversized for surge conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The surge vessel acts as an intermediary component between the slug catcher and downstream equipment. During surge conditions, it receives excess liquids and solids from the slug catcher, preventing them from reaching downstream equipment while allowing normal operation to continue.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the slug catcher is made larger to accommodate surge volumes, then surge handling capability improves, but the equipment cost increases

Engineering Contradiction:

Improvesurge handling capabilityVSAvoidequipment cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

By segmenting the reception function into two separate vessels, each vessel can be manufactured at optimal sizes and pressures, reducing overall equipment cost compared to a single oversized vessel designed for all conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The surge vessel serves as a cost-effective intermediary that handles surge conditions at lower pressure, reducing the pressure requirements and associated costs for the main slug catcher and downstream equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If pipeline pigs are used for cleaning operations, then pipeline maintenance is achieved, but large liquid slugs are generated that cause surges

Engineering Contradiction:

Improvepipeline cleaning capabilityVSAvoiddownstream equipment operation

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The surge vessel acts as a buffer or intermediary that absorbs the disruptive effect of liquid slugs generated during pigging operations, protecting downstream equipment from surge conditions while allowing cleaning operations to proceed.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surge vessel is positioned to receive liquid slugs before they can reach downstream equipment, cushioning the impact of surge conditions and preventing disruptions to downstream operations during and after pigging events.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

Ensures continuous supply of gaseous and liquid hydrocarbons to downstream processing units, prevents shutdowns, and allows for more economical slug catcher design by managing surges through a separate surge vessel, operating at lower pressure, thus maintaining operational efficiency and reducing the need for larger, more expensive equipment.

Implementation Method 1

separating at least a portion of the gaseous hydrocarbons from the rest of the fluid to leave a liquid mixture or a liquid/solid mixture

Methodology Applied

Scientific EffectPhase separation: Phase Change

Implementation Method 2

directing at least a portion of the liquid mixture or the liquid/solid mixture from the slug catcher to a surge vessel

Methodology Applied

Scientific EffectAccumulation:

Data Source

PatentUS7947121B2Method for receiving fluid from a natural gas pipeline

Publication Date: 2011.05.24 SHELL USA INC

AI summary

A method for receiving fluid from a natural gas pipeline, the fluid comprising gaseous hydrocarbons, liquid hydrocarbons, water and optionally solids, the method comprising: (a) in a slug catcher (10), receiving the fluid comprising gaseous hydrocarbons, liquid hydrocarbons, water and optionally solids from at least one pipeline (20a, 20b, 20c) (b) in the slug catcher (10), separating at least a portion of the gaseous hydrocarbons from the rest of the fluid to leave a liquid mixture or a liquid/solid mixture; (c) directing at least a portion of the liquid mixture or liquid/solid mixture to a separation vessel (14), preferably a three-phase separation vessel; and (d) in the event of a surge of liquids and optionally solids to the slug catcher (10), directing at least a portion of the liquid mixture or the liquid/solid mixture from the slug catcher (10) to a surge vessel (12).