Headspace Recycle Loop for Ethylene Oligomerization

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Solution Overview

Problem

Oligomerization processes in gas/liquid reactors face significant losses of unreacted ethylene due to breakthrough in the headspace, leading to reduced productivity and increased costs, as existing methods fail to effectively manage the gas phase and limit ethylene loss.

Innovation Solution

Implementing a headspace recycle loop that reintroduces gaseous fractions from the upper zone into the lower part of the liquid phase, optimizing ethylene dissolution and regulating reactor pressure, thereby reducing ethylene loss and enhancing the production of linear alpha-olefins like 1-butene, 1-hexene, and 1-octene.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the headspace is purged to remove gaseous compounds, then the selectivity for desired linear alpha-olefins is improved, but the loss of unreacted ethylene increases significantly

Engineering Contradiction:

Improveselectivity for linear alpha-olefinsVSAvoidloss of unreacted ethylene

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The invention converts the harmful loss of ethylene in the headspace purge into a beneficial resource by recycling the gaseous fraction back into the liquid phase. The ethylene that would otherwise be wasted is now reintroduced and dissolved in the liquid phase where it can participate in the oligomerization reaction, thereby improving both selectivity and reducing material loss.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention implements a recovery system for the gaseous fraction withdrawn from the headspace. Instead of discarding this fraction during purging operations, it is recovered and reintroduced into the liquid phase, allowing the unreacted ethylene to be recovered and reused in the reaction process.

Inventive Principle:

Principle #34Discarding and recovering

2Quantity of substance

If the amount of gaseous ethylene in the headspace is substantial, then the breakthrough phenomenon increases, but the productivity of the oligomerization process decreases

Engineering Contradiction:

Improveamount of gaseous ethyleneVSAvoidproductivity of oligomerization process

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The invention ensures continuous utilization of ethylene by recycling the gaseous fraction back into the liquid phase. This continuous action prevents ethylene from being lost during purging and ensures that the oligomerization reaction can proceed continuously with maximum conversion efficiency, thereby maintaining high productivity.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The invention implements a feedback loop where the gaseous fraction containing unreacted ethylene is monitored, withdrawn from the headspace, and reintroduced into the liquid phase. This feedback mechanism ensures that ethylene is continuously recovered and reused, optimizing the quantity of ethylene available for reaction and maintaining high productivity.

Inventive Principle:

Principle #23Feedback

3Length of stationary object

If the height of the liquid phase is reduced, then the contact time for ethylene dissolution decreases, but the breakthrough level increases

Engineering Contradiction:

Improveheight of liquid phaseVSAvoidbreakthrough level

Core Design Contradiction:

Length of stationary objectVSLoss of substance

Solution Approach 1:

The invention applies preliminary action by reintroducing the gaseous fraction into the liquid phase before it can be lost during purging. This preliminary recovery and reintroduction ensures that ethylene has another opportunity to dissolve and react, compensating for the reduced contact time caused by lower liquid phase height.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention converts the harmful effect of reduced dissolution time into a benefit by recycling the gaseous fraction. The ethylene that would have been lost due to insufficient contact time is now recovered and given another chance to dissolve and react, thereby reducing breakthrough levels despite the reduced liquid phase height.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 increases the saturation of dissolved ethylene, improving the oligomerization process's productivity and selectivity while maintaining low ethylene loss, irrespective of reactor dimensions, and allows for economic compensation of ethylene breakthrough.

Implementation Method 1

a step of recycling a gaseous fraction, withdrawn from the upper zone of the reaction chamber and introduced at the lower part of the reaction chamber, into the liquid fraction

Methodology Applied

Scientific EffectDissolution: Absorption (physical)

Implementation Method 2

a step of cooling the fraction withdrawn in step c) by passing said fraction into a heat exchanger

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS11786878B2Oligomerization process using a recycle of gaseous headspace

Publication Date: 2023.10.17 IFP ENERGIES NOUVELLES

AI summary

The present invention relates to an oligomerization process implemented in a gas/liquid reactor comprising a headspace recycle loop. The process more particularly relates to the oligomerization of ethylene to linear alpha-olefins such as 1-butene, 1-hexene, 1-octene or a mixture of linear alpha-olefins.