Multiple reflux stream hydrocarbon recovery process

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Solution Overview

Problem

Existing cryogenic processes for recovering ethane and heavier hydrocarbon components from gas streams are limited by the maximum recovery achievable with current reflux stream configurations, and there is a need for processes that can efficiently transition between high throughput and high recovery modes while minimizing operating and capital costs.

Innovation Solution

A system and method that allows flexible operation by switching between using residue gas and feed gas as reflux to a demethanizer tower, enabling high ethane recovery or high throughput modes through controlled valve positioning and heat exchanger configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single tower with reflux stream from hydrocarbon gas feed stream is used, then the process structure is simple, but the maximum recovery of ethane is limited

Engineering Contradiction:

Improveprocess structureVSAvoidethane recovery

Core Design Contradiction:

Device complexityVSQuantity of substance

Solution Approach 1:

The single tower is segmented into multiple towers (demethanizer, deethanizer, depropanizer) with intermediate condensers and reboilers. This segmentation allows each tower to perform a specific separation function, thereby increasing ethane recovery while maintaining manageable process complexity through functional decomposition.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The process transitions from a single-dimensional (one tower) to a multi-dimensional configuration by adding towers at different heights, intermediate condensers, and reboilers. This spatial and functional dimensionality increase enables multiple reflux streams and feed points, significantly improving ethane recovery capability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If cryogenic processes are used to achieve high recovery rates of ethane and heavier components, then recovery efficiency is improved, but operating and capital costs increase

Engineering Contradiction:

Improveethane recovery rateVSAvoidoperating and capital costs

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

Multiple towers are merged into an integrated system where the overhead of one tower serves as feed or reflux for another. The intermediate condensers and reboilers merge thermal energy streams, allowing heat recovery and reducing overall energy consumption while achieving high ethane recovery rates.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system implements feedback loops where overhead streams are condensed and returned as reflux to previous towers. This feedback mechanism optimizes separation efficiency and reduces energy losses by recycling thermal energy within the system, thereby lowering operating costs while maintaining high recovery rates.

Inventive Principle:

Principle #23Feedback

3Quantity of substance

If the process is designed for high recovery mode, then ethane recovery is maximized, but throughput is reduced

Engineering Contradiction:

Improveethane recoveryVSAvoidthroughput

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The process design incorporates dynamic capabilities through multiple feed points and adjustable reflux ratios. Operators can dynamically adjust the configuration to switch between high recovery mode (using residue gas as reflux) and high throughput mode (using feed gas as reflux), allowing the system to adapt to varying market demands and optimize both recovery and productivity as needed.

Inventive Principle:

Principle #15Dynamics

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

Enables efficient recovery of ethane and heavier hydrocarbons with flexibility to adapt to market demands, increasing throughput by 20% while maintaining high ethane recovery, and optimizing operational efficiency with minimal capital investment.

Implementation Method 1

A first heat exchanger may be provided for cooling the first feed stream, and a second heat exchanger may be provided for cooling the second feed stream

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

A separator may be provided for separating the cooled first and second feed streams into a first vapor stream and a first liquid stream

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 3

The demethanizer tower may separate the feed streams into a demethanizer overheads stream and a demethanizer bottoms stream

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 4

One or more compressors may be provided for compressing the demethanizer overheads stream to form a residue gas stream

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS20260002729A1Multiple reflux stream hydrocarbon recovery process

Publication Date: 2026.01.01 LUMMUS TECHNOLOGY INC

AI summary

Systems herein separate an inlet gas stream containing methane, C2 components, C3 components and optionally heavier hydrocarbons into a volatile gas fraction containing methane and a less volatile hydrocarbon fraction containing C2+ components. The system may include piping, valving, and controls configured to flexibly allow the system to operate in a high ethane recovery mode, a high throughput mode, or in some embodiments, a high propane recovery mode.