Two-Stage Distillation for Olefin Polymerization Stream Recycling
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Solution Overview
Problem
Current distillation systems for recycling hydrocarbon-containing feed streams in olefin polymerization processes face inefficiencies in separating lighter components like H2, N2, O2, CO, and CO2 from diluents, leading to sub-optimal polymerization conditions and increased costs due to energy-intensive separation methods and high monomer loss.
Innovation Solution
A process involving a two-stage distillation system with condensation and separation cycles to recover hydrocarbon diluent and olefin monomer streams, reducing hydrogen content and minimizing monomer loss, allowing for efficient recycling of streams in bimodal polyolefin production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional distillation systems are used to separate lighter components from diluent, then separation is achieved, but energy consumption increases and polymerization efficiency decreases
Solution Approach 1:
The patent extracts and removes lighter components (H2, N2, O2, CO, CO2) from the diluent stream using a dedicated removal system before recycling the diluent to the polymerization reactor. This extraction approach prevents these components from interfering with polymerization while avoiding the energy-intensive traditional distillation process, thereby maintaining polymerization efficiency and reducing energy consumption.
Solution Approach 2:
The patent changes the separation parameters by using a selective removal process rather than conventional distillation. By altering the separation mechanism and operating parameters, the system achieves effective removal of lighter components with lower energy input, resolving the contradiction between energy consumption and polymerization efficiency.
2Quantity of substance
If complicated distillation processes are used to capture diluent, then diluent recovery is improved, but device complexity and costs increase
Solution Approach 1:
The patent uses a targeted extraction approach to remove lighter components from the diluent stream, simplifying the overall separation process. Instead of employing complicated multi-stage distillation systems, the invention extracts the problematic components directly, achieving effective diluent recovery with reduced device complexity and lower costs.
3Quantity of substance
If traditional separation methods are used, then diluent can be recovered, but monomer loss increases due to sub-optimal separation
Solution Approach 1:
The patent extracts lighter components that interfere with optimal separation, enabling better monomer-diluent separation. By removing these interfering substances first, the system achieves more efficient monomer recovery and reduces monomer loss while maintaining diluent recovery, directly addressing the trade-off between these two parameters.
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 optimizes the recycling of hydrocarbon streams, reducing energy consumption, minimizing monomer loss, and enhancing polymerization efficiency by separating streams suitable for different reactor configurations, thereby reducing production costs and environmental impact.
Implementation Method 1
a) introducing said feed stream into a first distillation column for subjecting said feed to distillation conditions adapted to remove a1) a bottom stream comprising hydrocarbon diluent and one or more optional co-monomer, and a2) an overhead stream comprising hydrocarbon diluent, olefin monomer and components such as H2, N2, O2, CO, CO2, and formaldehyde
Implementation Method 2
b) condensing the overhead stream issued from the first distillation column in step a2) to form a condensate and storing said condensate in a separator (108) adapted to separate a vapor stream and a liquid stream
Data Source
AI summary
The present invention relates to a process for recycling product streams that have been separated from a hydrocarbon-containing feed stream comprising olefin monomer, olefin co-monomer, hydrocarbon diluent and components such as H2, N2, O2, CO, CO2, and formaldehyde. In accordance with the present process a hydrocarbon-containing feed stream is separated into a) a first side stream comprising hydrocarbon diluent and olefin monomer; b) a second side stream which is substantially hydrogen-free and comprises hydrocarbon diluent and olefin monomer, c) a bottom stream comprising substantially olefin-free hydrocarbon diluent, and d) an overhead vapor stream comprising olefin monomer, hydrocarbon diluent and components such as formaldehyde, H2, N2, O2, CO and CO2. The present process further includes recycling said first and said second side streams in a polymerization process for preparing bimodal polyolefin.