Olefin Polymerization Reactor Feed Zoning for Broader MWD Control
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Solution Overview
Problem
Existing methods for controlling molecular weight distribution and comonomer composition distribution in polymerization processes add complexity and cost, and existing polymerization reactors do not adequately broaden these distributions to achieve desired characteristics in melt and orientation processability.
Innovation Solution
A reactor configuration with a first and second inlet for introducing streams of reactants, allowing control of gradients in temperature and component concentrations within the reactor to modify polymer properties, enabling narrower or broader molecular weight and comonomer composition distributions without altering the reactor assembly or catalyst composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If series or parallel reactors are used to broaden molecular weight distribution, then the molecular weight distribution breadth is improved, but the process complexity and costs increase
Solution Approach 1:
The patent segments the polymerization process by introducing a second stream at a specific location within the reactor, creating distinct reaction zones with different conditions. This allows different molecular weight fractions to be formed in different zones, achieving broad MWD without using multiple reactors
Solution Approach 2:
The patent adds a spatial dimension to the polymerization process by introducing a second feed stream at a specific location within the reactor. This creates a gradient along the reactor length, allowing continuous variation of reaction conditions and thus broadening MWD in a single reactor
2Productivity
If metallocene catalysts are used, then the polymerization efficiency is improved, but the molecular weight distribution and comonomer composition distribution become too narrow
Solution Approach 1:
The patent applies local quality by creating different reaction conditions at different locations within the reactor. The second stream introduction creates zones with varying monomer, comonomer, and catalyst concentrations, allowing different polymer characteristics to form in different zones while using a single metallocene catalyst system
Solution Approach 2:
The patent changes reaction parameters (concentration, temperature) along the reactor length by introducing a second stream. This creates gradients in monomer, comonomer, and catalyst concentrations, allowing the same catalyst to produce a broad MWD and CCD through parameter variation rather than catalyst modification
3Stability of the object's composition
If the reactor mixing behavior is changed to broaden molecular weight distribution, then the molecular weight distribution breadth is improved, but the mixing behavior is difficult to control without modifying reactor design
Solution Approach 1:
The patent performs preliminary action by introducing the second stream at a specifically designed location within the reactor before the main reaction zone. This creates controlled gradients and mixing patterns that broaden MWD without requiring modification of the overall reactor design or assembly
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 allows for precise adjustment of molecular weight and comonomer composition distributions, enhancing melt and orientation processability by modifying reaction conditions within the reactor, thus improving polymer properties.
Implementation Method 1
manipulating gradients of concentration and temperature within the reactor
Implementation Method 2
manipulating gradients of concentration and temperature within the reactor
Implementation Method 3
polymerizing a polymer from the reaction mixture
Data Source
AI summary
A reactor for the polymerization of olefins comprising a first inlet for introducing a first stream comprising monomer(s), catalyst(s) and optionally hydrogen, solvent or comonomer(s) and/or mixtures thereof, at least one outlet for withdrawing a product stream, characterized in that the reactor further comprises at least one second inlet for introducing a second stream comprising monomer(s), catalyst(s) and optionally hydrogen, solvent or comonomer(s) and/or mixtures thereof; and a process for polymerizing olefins in a reactor according to the present invention, comprising the steps of introducing monomer(s), catalyst(s), and optionally hydrogen, solvent or comonomer(s) and/or mixtures thereof as the first stream via the first inlet into the reactor forming a reaction mixture; polymerizing a polymer from the reaction mixture; withdrawing the product stream via the at least one outlet from the reactor; characterized in that the process comprises a further step of introducing a second stream comprising monomer(s), catalyst(s), and optionally hydrogen, solvent or comonomer(s) and/or mixtures thereof into the reactor via the at least one second inlet into the reactor.