Two-Step Distillation for Ethylene Separation from Ethane

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Solution Overview

Problem

Current processes for separating ethylene from unconverted ethane and light components in ethane oxidative dehydrogenation (ODH) effluent are inefficient in terms of energy demand and capital expenditure.

Innovation Solution

A two-step distillation process where ethylene and light components are first separated from unconverted ethane at a lower top column pressure, followed by a second distillation at a higher pressure to separate ethylene from light components, reducing energy consumption and maintaining high purity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single distillation step is used to separate ethylene from unconverted ethane and light components, then the separation process is simpler, but the energy demand and capital expenditure increase

Engineering Contradiction:
Improveseparation process complexityVSAvoidenergy demand
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The separation process is divided into two distinct distillation steps: first separating ethylene and light components from unconverted ethane, then separating ethylene from light components. This segmentation reduces energy demand and capital expenditure compared to a single comprehensive distillation step.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If traditional distillation methods are used for separating ethylene, ethane and light components, then the separation is achieved, but the total energy consumption is high

Engineering Contradiction:
Improveseparation purityVSAvoidtotal energy consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The process utilizes changes in pressure parameters between the two distillation steps. The first distillation operates at one pressure condition to separate ethylene and light components from ethane, while the second distillation operates at a different pressure to separate ethylene from light components. This parameter optimization reduces total energy consumption while maintaining high separation purity.

Inventive Principle:
Principle #35Parameter changes

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 results in a more energy-efficient process with lower energy demand and higher purity of ethylene and ethane, as demonstrated by the Examples, which show reduced total energy needed for separation compared to traditional methods.

Implementation Method 1

in a first distillation step ethylene and light components are separated from unconverted ethane and in a later, second distillation step ethylene is separated from light components

Methodology Applied
Scientific EffectDistillation: Distillation

Data Source

PatentEP3873876B1Production of ethylene by oxidative dehydrogenation of ethane
Publication Date: 2023.09.27 SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV
  • EP3873876B1 patent drawingFigure 1
  • EP3873876B1 patent drawingFigure 2

AI summary

The invention relates to a process for the production of ethylene by oxidative dehydrogenation of ethane, comprising: a) subjecting a stream comprising ethane to oxidative dehydrogenation conditions, resulting in a stream comprising ethylene, unconverted ethane and light components; b) subjecting ethylene, unconverted ethane and light components from the stream resulting from step a) to distillation, resulting in a stream comprising ethylene and light components and a stream comprising unconverted ethane; c) optionally recycling unconverted ethane from the stream comprising unconverted ethane resulting from step b) to step a); and d) subjecting ethylene and light components from the stream comprising ethylene and light components resulting from step b) to distillation at a top column pressure which is higher than the top column pressure in step b), resulting in a stream comprising light components and a stream comprising ethylene.