Polyolefin Production With Concentrated Slurry and Parallel Reactors
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Solution Overview
Problem
Existing multistage polymerization processes for alpha-olefin polymers face challenges such as catalyst residence time limitations, reduced productivity, high monomer loss, and limited flexibility in polymer design due to inefficient transfer of polymer intermediates between reactors.
Innovation Solution
A process involving a slurry reactor followed by two gas phase reactors, where polymer slurry is concentrated and split into streams for parallel polymerization, allowing for higher solid concentrations and reduced catalyst residence time, thereby enhancing productivity and flexibility in polymer design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymer slurry is transferred from slurry reactor to gas phase reactor, then polymerization continues in gas phase, but catalyst residence time increases and productivity decreases
Solution Approach 1:
The process segments the polymerization into distinct stages: slurry phase polymerization in a first reactor, followed by gas phase polymerization in a second reactor. The polymer slurry from the first reactor is separated into a polymer-rich phase and a monomer-rich phase, with only the polymer-rich phase being transferred to the second reactor. This segmentation prevents catalyst carryover and extends effective catalyst residence time while maintaining high productivity.
2Adaptability or versatility
If polymer slurry is transferred between reactors, then multistage polymerization is achieved, but monomer loss increases due to inefficient transfer
Solution Approach 1:
The process extracts and separates the monomer-rich phase from the polymer slurry before transfer to the next reactor stage. By removing the monomer-containing fluid phase through separation equipment (such as decanters, centrifuges, or filters), the system minimizes monomer loss during transfer while still achieving the desired multistage polymerization and polymer design flexibility.
3Productivity
If solid concentration in polymer slurry is increased, then productivity improves, but transfer efficiency between reactors decreases
Solution Approach 1:
The process applies local quality by creating two distinct phases with different properties: a polymer-rich phase with high solid concentration for productivity, and a monomer-rich fluid phase for easy transfer. By separating these phases before reactor transfer, the system achieves both high production rates and efficient transfer between reactors, as only the polymer-rich phase needs to be transferred at high concentration.
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 process achieves higher production rates, reduces monomer loss, and enables the production of multimodal polymers with tailored properties by operating gas phase reactors in parallel, ensuring stable operation and efficient transfer of reactants.
Implementation Method 1
concentrating at least a part of the polymer slurry by removing a part of the fluid phase
Implementation Method 2
diluting at least a part of the polymer slurry by adding a part of fluid phase
Implementation Method 3
transfer of the polymer slurry from said first reactor to said second and/or third gas phase reactor
Data Source
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AI summary
The present invention relates to a process and apparatus for producing alpha-olefin polymers in the presence of a polymerization catalyst in a continuously operated multistage polymerisation sequence, the process comprising the steps of (a) polymerizing an alpha-olefin monomer and optionally one or more alpha-olefin co-monomers in a slurry reactor in the presence of a hydrocarbon diluent or liquid monomer in a slurry phase to obtain an alpha-olefin polymer, the slurry phase having a first concentration of solids, (b) continuously withdrawing from the slurry reactor a polymer slurry containing polymer and a fluid phase, (c) concentrating at least a part of the polymer slurry by removing a part of the fluid phase to provide a 1st product stream comprising a concentrated slurry having a second solids concentration, which is higher than the first solids concentration, and a 2nd product stream mainly comprising the fluid phase, (d) polymerizing said 1st product stream in the presence of alpha-olefin monomers and optionally one or more alpha-olefin co-monomers in a first gas phase reactor (GPR1) arranged downstream of said slurry reactor to obtain a 1st alpha-olefin product stream, (e) polymerizing a 3rd product stream, withdrawn from said slurry reactor, in the presence of alpha-olefin monomers and optionally one or more alpha-olefin co-monomers in a second gas phase reactor (GPR2) to obtain a 2nd alpha-olefin product stream.