Perforated Flash Separator Inlet for Olefin Copolymer Separation

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Solution Overview

Problem

Existing flash separators face challenges in achieving high separation efficiency of volatile gases from viscous olefin copolymers, particularly large molecules like comonomers, while minimizing droplet entrainment, which leads to fouling and increased maintenance costs.

Innovation Solution

A flash separator inlet with a perforated cylindrical wall featuring holes of 15 µm to 1500 µm size is used to distribute the reaction mixture, enhancing the separation efficiency by increasing the surface area and reducing droplet carry-over, thereby minimizing fouling and maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the polymer melt is fed directly into the flash separator, then the separation process is simple, but the mass transfer efficiency of volatile gases is insufficient and droplet entrainment increases

Engineering Contradiction:
Improvemass transfer efficiencyVSAvoidinlet structure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The inlet is segmented into multiple perforations distributed across its surface, creating multiple injection points that distribute the polymer melt into finer droplets. This segmentation increases the total surface area for mass transfer while preventing large droplet formation that would cause entrainment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The inlet functions as a porous structure with multiple perforations of varying sizes (15-1500 µm). This porous configuration allows the polymer melt to be distributed through numerous small openings, creating a fine dispersion of droplets that enhances mass transfer efficiency while minimizing droplet entrainment in the gas stream.

Inventive Principle:
Principle #31Porous materials

2Productivity

If smaller polymer droplets are used to enhance mass transfer, then the mass transfer rate increases, but the risk of droplet carry-over into the gas stream increases

Engineering Contradiction:
Improvemass transfer rateVSAvoiddroplet carry-over risk
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

Different regions of the inlet have different perforation sizes (15-1500 µm), creating local variations in droplet formation. This local quality differentiation allows optimization of droplet size distribution to achieve high mass transfer rates while preventing carry-over of the smallest, most entrainable droplets into the gas stream.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the physical parameters of the inlet structure by incorporating perforations of specific size ranges (15-1500 µm). This parameter modification controls the droplet formation process, creating an optimal distribution that balances mass transfer efficiency with droplet retention in the liquid phase.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If flash separators operate with viscous polymer solutions, then the separation process is straightforward, but fouling of downstream heat exchangers and compressors increases

Engineering Contradiction:
Improveseparation process simplicityVSAvoidfouling of downstream equipment
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The inlet structure performs preliminary action by distributing the polymer melt into fine droplets before the separation process begins. This pre-distribution reduces the likelihood of large droplet formation and carry-over, thereby preventing fouling of downstream heat exchangers and compressors while maintaining operational simplicity.

Inventive Principle:
Principle #10Preliminary action

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

The solution achieves improved separation efficiency with reduced droplet entrainment, minimizing heat exchanger and compressor blockages, and lowering cleaning and maintenance efforts in downstream processing units.

Implementation Method 1

The object is to increase the mass transfer of volatile gases from the viscous polymer melt

Methodology Applied
Scientific EffectMass transfer: Diffusion

Implementation Method 2

separating an olefin copolymer from volatile gases

Methodology Applied
Scientific EffectPhase change: Phase Change

Implementation Method 3

the pressure of the reaction mixture at the reactor outlet, is decreased from its operating value of about 1000 to 3000 bar to a value of 100 to 300 bar

Methodology Applied
Scientific EffectPressure reduction: Depressurisation

Implementation Method 4

The reaction mixture expansion caused by the let-down valve, results in a temperature increase of the outlet reaction stream (i.e., reverse Joule-Thompson effect)

Methodology Applied
Scientific EffectJoule-Thomson effect: Joule-Thomson Effect

Implementation Method 5

a stream of droplets falling downwards within the flash separator

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP3515955B1Method for separating hydrocarbons from polymer
Publication Date: 2023.01.04 BOREALIS AG
  • EP3515955B1 patent drawingFigure 1

AI summary

The present invention is directed to a process for separating an olefin copolymer from volatile gases using a flash separator. The flash separator can be used with a solution or high pressure process. The mass transport of volatile gases from the viscous polymer melt is increased.