Ethylene Recovery via Absorption at Moderate Temperatures

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Solution Overview

Problem

The production of polyethylene is hindered by significant energy costs and capital expenditures due to the need for high-purity feedstocks and inefficient processes for recovering unreacted ethylene from polymerization reactions, which often require multiple distillation columns and cryogenic temperatures.

Innovation Solution

A process involving the separation of a light gas stream from the polymerization product stream, followed by contact with an absorption solvent system at temperatures between 40°F to 110°F, where unreacted ethylene is absorbed and subsequently recovered, allowing for its reuse in the polymerization reactor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple distillation columns and cryogenic temperatures are used to purify feedstock, then high purity ethylene is obtained, but energy consumption and capital costs increase significantly

Engineering Contradiction:

Improvefeedstock purityVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the temperature parameter from cryogenic ranges to ambient or mildly elevated temperatures (40°F to 110°F) for the absorption process, eliminating the need for expensive cryogenic equipment while achieving effective ethylene recovery and purification

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an absorption solvent as an intermediary substance that selectively absorbs ethylene from the gas stream at moderate temperatures, replacing the need for direct cryogenic distillation and associated high energy consumption

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If multiple distillation columns are operated to separate light gases, then high purity monomers are produced, but capital expenditures and infrastructure requirements increase

Engineering Contradiction:

Improvemonomer purityVSAvoidnumber of distillation columns

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts ethylene selectively from the light gas stream using an absorption solvent, removing the need for multiple distillation columns and complex separation infrastructure while achieving the required purity for polymerization feedstock

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent operates the absorption process at temperatures of 40°F to 110°F, which are significantly higher than cryogenic temperatures, thereby simplifying equipment requirements and reducing capital expenditures while maintaining effective separation

Inventive Principle:

Principle #35Parameter changes

3Loss of substance

If conventional purification processes are used to recover unreacted monomers, then feedstock is reclaimed, but energy costs and operational complexity increase

Engineering Contradiction:

Improveunreacted monomer recoveryVSAvoidoperational energy costs

Core Design Contradiction:

Loss of substanceVSUse of energy by moving object

Solution Approach 1:

The patent employs an absorption solvent as a mediator that selectively binds to unreacted ethylene in the recycle stream at moderate temperatures, enabling efficient recovery and reuse of monomers without the high energy costs of conventional thermal separation processes

Inventive Principle:

Principle #24Intermediary (Mediator)

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 process enhances the efficiency of polyethylene production by reducing energy consumption and capital costs associated with feedstock purification, while effectively recycling unreacted ethylene, thereby improving overall production efficiency and reducing waste.

Implementation Method 1

contacting the light gas stream with an absorption solvent system, wherein the contacting the light gas stream with the absorption solvent system occurs at a temperature in a range of from about 40° F. to about 110° F., wherein at least a portion of the unreacted ethylene from the light gas stream is absorbed by the absorption solvent system

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS9580370B2Ethylene recovery by absorption

Publication Date: 2017.02.28 CHEVRON PHILLIPS CHEMICAL COMPANY LP

AI summary

A process for recovery of ethylene from a polymerization product stream of a polyethylene production system, comprising separating a light gas stream from the polymerization product stream, wherein the light gas stream comprises ethane and unreacted ethylene, contacting the light gas stream with an absorption solvent system, wherein the contacting the light gas stream with the absorption solvent system occurs at a temperature in a range of from about 40° F. to about 110° F., wherein at least a portion of the unreacted ethylene from the light gas stream is absorbed by the absorption solvent system, and recovering unreacted ethylene from the absorption solvent system to yield recovered ethylene.