LNG process for variable pipeline gas composition

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Solution Overview

Problem

LNG facilities face instability due to wide variability in feed gas compositions, leading to frequent process upsets and inefficiencies, particularly when processing pipeline gas, as existing systems struggle to manage high levels of heavy hydrocarbons and require frequent adjustments in operating setpoints.

Innovation Solution

A system with a heavies removal unit and a purge/recovery line that adjusts the rate of purging undesirable components into a methane recycle stream, stabilizing the LNG process across a wide range of compositions by recycling heavy components and reducing the need for flaring or fueling, allowing for a single set of operating conditions for 80% of the feed range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the feed gas composition varies widely, then the facility can process diverse pipeline gas, but the liquefaction process becomes unstable and requires frequent adjustments

Engineering Contradiction:

Improvefeed gas composition rangeVSAvoidliquefaction process stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system dynamically adjusts the purging rate of heavy components from the heavies removal column based on feed composition variations. By making the purging rate variable rather than fixed, the system can adapt to different feed compositions while maintaining stable distillation column operation and consistent LNG product quality

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses composition analysis of the feed gas to determine the appropriate purging rate. This feedback mechanism allows the control system to respond to composition changes and adjust operating parameters accordingly, maintaining process stability despite variable feed conditions

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If the purging rate of heavy components is increased, then the concentration of heavy components in the distillation column is controlled, but methane is lost in the purge stream

Engineering Contradiction:

Improveheavy component concentration controlVSAvoidmethane loss

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The system optimizes the purging rate parameter based on feed composition to achieve the minimum necessary purging for heavy component control. By carefully adjusting this parameter, the system maintains precise concentration control in the distillation column while minimizing methane loss in the purge stream

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the facility operates with frequent setpoint adjustments, then it can handle variable feed composition, but operational complexity and intervention requirements increase

Engineering Contradiction:

Improvefeed composition variability handlingVSAvoidoperator intervention frequency

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The system automatically adjusts the purging rate based on feed composition analysis without requiring manual intervention. The control system self-regulates to maintain stable operation across variable feed conditions, reducing the need for operator adjustments and simplifying operation

Inventive Principle:

Principle #25Self-service

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

The system provides stable and efficient LNG processing with minimal operator intervention, conserving refrigeration horsepower, and allowing for a wider range of compositions to be processed without the need for frequent adjustments, thereby improving operational stability and reducing waste.

Implementation Method 1

A natural gas feed is introduced into a heavies removal unit, wherein the heavies removal system includes a heavies removal column and a distillation column

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 2

One or more heavy components of the natural gas feed is purged from the heavies removal column to a methane recycle stream via the purge/recovery line

Methodology Applied

Scientific EffectGas flow transfer:

Data Source

PatentUS20220364005A1LNG process for variable pipeline gas composition

Publication Date: 2022.11.17 CONOCOPHILLIPS CO

AI summary

The invention relates to a system, method and apparatus for processing natural gas in an LNG facility. A natural gas feed is introduced into a heavies removal unit. The heavies removal system includes a heavies removal column and a distillation column. The heavies removal column and the distillation column are connected via a purge/recovery line. One or more components of the natural gas feed is purged from the heavies removal column to the distillation column via the purge/recovery line to obtain a specified concentration or concentration range of heavy components feeding into the distillation column.