Light Oil Reflux in Heavies Removal Columns Without Gas Compression

Solution Overview

Problem

The existing heavies removal system in the LNG Optimized Cascade Process faces increased operating and capital expenditures due to higher lean reflux rates required for processing leaner natural gas feeds, leading to increased natural gas flow and compression needs.

Innovation Solution

The implementation of a light oil reflux stream, either C4-C5 or external condensate, reduces the need for gas compression and enhances separation efficiency in the heavies removal column, allowing for leaner feed processing without the need for reflux gas compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If lean reflux rate is increased to remove C6+ components from leaner natural gas feeds, then heavies removal efficiency is improved, but operating and capital expenditures increase due to increased natural gas flow to compressors

Engineering Contradiction:

Improveheavies removal efficiencyVSAvoidoperating and capital expenditures

Core Design Contradiction:

Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The patent changes the physical state parameter of the reflux stream from gaseous to liquid by condensing it before reintroduction to the heavies removal column. This parameter change eliminates the need for compression of the reflux stream, thereby reducing energy consumption and operating costs while maintaining the required reflux rate for effective C6+ component removal.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical compression system with a thermal condensation system. Instead of using compressors to pressurize the reflux gas stream, the invention uses heat exchangers to condense the reflux stream into liquid form, which then flows back to the column by gravity or pressure differential, eliminating the need for reflux stream compression.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If lean reflux rate is increased to maintain separation performance, then heavies removal capability is improved, but device complexity increases due to additional compression equipment

Engineering Contradiction:

Improveseparation performanceVSAvoidcompression equipment

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the physical state parameter of the reflux stream from gaseous to liquid by condensing it before reintroduction to the heavies removal column. This parameter change eliminates the need for compression of the reflux stream, thereby reducing energy consumption and operating costs while maintaining the required reflux rate for effective C6+ component removal.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical compression system with a thermal condensation system. Instead of using compressors to pressurize the reflux gas stream, the invention uses heat exchangers to condense the reflux stream into liquid form, which then flows back to the column by gravity or pressure differential, eliminating the need for reflux stream compression.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly reduces operational expenditures by over 80% and increases separation efficiency, enabling the processing of very lean gas feeds with minimal energy usage and storage requirements.

Implementation Method 1

The implementation of a light oil reflux stream, either C4-C5 or external condensate, reduces the need for gas compression and enhances separation efficiency in the heavies removal column

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 2

the debutanizer column overhead lights go to a flash drum where flash drum bottoms is pumped through a heat exchanger as a light oil reflux input to the heavies removal column

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS11713423B2Light oil reflux heavies removal process

Publication Date: 2023.08.01 CONOCOPHILLIPS CO

AI summary

The invention relates to various nonlimiting embodiments that include methods, apparatuses or systems for processing natural gas comprising a heavies removal column processing natural gas and light oil reflux. The overhead stream goes to heavies treated natural gas storage. The heavies removal column reboiler bottoms stream product is input to a debutanizer column. The debutanizer column overhead lights are input to a flash drum where the bottoms is pumped through a heat exchanger as a light oil reflux input to the heavies removal column, while the debutanizer reboiler bottoms product is stored as stabilized condensate. Alternatively, debutanizer column overhead lights are sent to heavies treated gas storage and the bottoms stream product goes to a depentanizer column, the overhead lights are pumped through a heat exchanger as a light oil reflux input to the heavies removal column, while the depentanizer reboiler bottoms product is stabilized condensate.