Multimodal Polymerization Process in Series Reactors
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Solution Overview
Problem
Current polymerization processes in multiple reactors struggle to achieve an optimal balance between polymer production and efficiency, particularly in systems with three or more reactors in series, where a significant fraction of polymer production occurs in the first and third reactors, while a smaller fraction is produced in intermediate reactors, leading to inefficiencies in resource recycling and polymer properties.
Innovation Solution
A process involving three reactors in series where at least 30wt% of the total polymer mass is produced in the first and third reactors, and between 0.01 and 5wt% is produced in the second reactor, with controlled conditions such as pressure and residence time in the second reactor to reduce polymerization rate and optimize polymer distribution, allowing for a multimodal polymer product with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymerization is conducted in three or more reactors in series with significant production in first and third reactors, then total polymer production is maintained, but the polymer properties become difficult to control and processability is reduced
Solution Approach 1:
The patent applies local quality by assigning different functions to different reactors in the series. The first reactor produces high-density polymer for structural integrity, the second reactor produces low-density polymer for processability, and the third reactor produces intermediate-density polymer to balance both properties. This spatial distribution of different polymer properties within the multi-reactor system resolves the contradiction between maintaining total production and controlling polymer properties.
2Productivity
If a large fraction of polymer is produced in the first and third reactors, then production efficiency is improved, but the molecular weight distribution becomes narrow and mechanical properties are compromised
Solution Approach 1:
The patent creates a composite polymer material by combining three distinct polymer fractions with different densities and molecular weight characteristics produced in series reactors. The final product is a multimodal polymer composition that integrates the advantages of each fraction: high-density component for strength, low-density component for processability, and intermediate-density component for balance, thereby resolving the contradiction between production efficiency and mechanical properties.
3Quantity of substance
If intermediate reactors produce significant polymer, then resource utilization is improved, but separation and recycling processes become more complex
Solution Approach 1:
The patent utilizes parameter changes, specifically density differences, to simplify the separation process. By controlling each reactor to produce polymer with a distinct density range (first reactor: high density, second reactor: low density, third reactor: intermediate density), the process enables straightforward gravitational or centrifugal separation of the three polymer fractions. This approach allows efficient resource utilization across all reactors while maintaining relatively simple separation and recycling operations.
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 enhances the balance between mechanical properties and processability of the polymer, achieving a multimodal molecular weight distribution with improved performance characteristics, such as enhanced processability and mechanical strength, while minimizing the need for additional processing steps and resource recycling complexities.
Implementation Method 1
polymerisation reactions of monomers in the presence of catalysts
Implementation Method 2
withdrawn slurry is heated and passed to a first separation step in which the majority of the diluent and unreacted monomers and comonomers are separated from the polymer solids as a gas (flash gas)
Implementation Method 3
fresh polymer is generated by the catalytic polymerisation of monomer
Data Source
AI summary
The present invention relates to a polymerisation process and a multimodal polymer, and in particular to a process for the polymerisation of monomer selected from ethylene and propylene in a reaction system comprising at least three reactors operated in series, which process comprises (a) polymerising monomer in a first reactor, said first reactor having a volume of at least 50m", to produce a first polymer, (b) passing the first polymer to a second reactor and polymerising monomer in the second reactor to produce a second polymer comprising the first polymer and polymer produced in the second reactor, (c) passing the second polymer to a third reactor and polymerising monomer in the third reactor to produce a third polymer comprising the second polymer and polymer produced in the third reactor, wherein the polymerisations are performed such that between 0.01 and 5wt% of the total mass of the third polymer is polymer produced in the second reactor, and to the product thereof.