Inert C6 Purge in Solution Polymerization Fractionation
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Solution Overview
Problem
Current solution polymerization processes face inefficiencies due to the accumulation of inert C6 components like isomers of hexane and hexene, which are not active in polymerization, leading to difficulties in polymer density control and increased energy consumption.
Innovation Solution
A process involving multiple separation steps, including flashing and fractionation, to separate and remove inert hydrocarbons, where a stream of solution is passed into a separator to create a liquid and vapor phase, with subsequent vapor streams being processed through multiple fractionators to isolate and purge inert C6 components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If unreacted monomer and comonomer are separated and recycled to the polymerisation process, then material efficiency is improved, but inert C6 components accumulate in the process
Solution Approach 1:
The separation process is divided into multiple sequential fractionation steps (first, second, and third fractionators) that segment the vapor stream into different components based on their boiling points, allowing selective removal of inert C6 components while recovering reactive monomers
Solution Approach 2:
The inert C6 components (isomers of hexane and hexene) are extracted and removed from the recycle stream through the third fractionator, preventing their accumulation in the polymerisation process while allowing the reactive components to be recycled
2Manufacturing precision
If multiple fractionation steps are added to remove inert C6 components, then polymer density control is improved, but device complexity increases
Solution Approach 1:
Each fractionator operates at different temperature and pressure parameters to separate components based on their unique boiling points, with the third fractionator specifically configured to remove inert C6 components at controlled conditions that optimize polymer density control
Solution Approach 2:
The fractionation system serves multiple functions: the first fractionator removes light ends, the second fractionator separates monomer from comonomer, and the third fractionator removes inert C6 components, with each unit performing a specific separation task that collectively achieves precise polymer density control
3Device complexity
If inert C6 components are not removed from the process, then process simplicity is maintained, but energy consumption increases
Solution Approach 1:
The inert C6 components are extracted and removed from the recycle stream through the third fractionator, preventing their accumulation that would otherwise require additional energy-intensive processing steps later in the process
Solution Approach 2:
The presence of inert C6 components, which would normally be harmful by accumulating and reducing process efficiency, is converted into a benefit by using their specific boiling point characteristics to enable efficient fractionation and separation, ultimately reducing overall energy consumption through optimized recycle stream composition
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 effectively removes inert C6 components, reducing energy consumption and operational costs, and allows for the potential reuse or further treatment of these components through isomerization or hydrogenation.
Implementation Method 1
passing a stream of a solution into a separator wherein a liquid phase comprising polymer and a vapour phase coexist
Implementation Method 2
passing at least a part of the vapour stream into a first fractionator; withdrawing a first overhead stream and a first bottom stream from the first fractionator
Data Source
AI summary
The present invention relates to a process for removing hydrocarbons comprising the steps of:(A) passing a stream of a solution into a separator wherein a liquid phase comprising polymer and a vapour phase coexist;(B) withdrawing a vapour stream and a concentrated solution stream from the separator;(C) passing at least a part of the vapour stream into a first fractionator;(D) withdrawing a first overhead stream and a first bottom stream from the first fractionator;(E) passing the first overhead stream to a second fractionator;(F) withdrawing a second overhead stream and a second bottom stream from the second fractionator;(G) passing the second overhead stream to a third fractionator;(H) withdrawing a third overhead stream and a third bottom stream from the third fractionator;characterised in that at least a part of the third bottom stream is withdrawn as a purge stream.