Hydrogen Removal Between Polyolefin Reactors
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Solution Overview
Problem
In polyolefin production, the transfer of chain transfer agents like hydrogen from one polymerization reactor to another can hinder the production of high-molecular-weight polyolefins by maintaining undesirably high concentrations in subsequent reactors, affecting polymer properties and efficiency.
Innovation Solution
A polyolefin reactor system with two loop reactors in series, utilizing a separation system such as a hydrocyclone to remove chain transfer agents from the slurry transferred between reactors, ensuring a lower hydrogen content in the second reactor, thereby optimizing polymer properties and production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chain transfer agents are transferred from the first reactor to the second reactor, then polymer production continues without interruption, but the hydrogen content in the second reactor becomes undesirably high, affecting polymer properties
Solution Approach 1:
The patent applies the extraction principle by removing the chain transfer agent (hydrogen) from the slurry stream between reactors. A separation system extracts hydrogen from the slurry discharged from the first reactor before it enters the second reactor, preventing excessive hydrogen accumulation while maintaining continuous production. This resolves the contradiction by taking out the harmful substance (excessive hydrogen) that would otherwise accumulate and degrade polymer properties.
Solution Approach 2:
The patent changes the hydrogen concentration parameter in the slurry stream between reactors. By controlling the separation process, the hydrogen content is adjusted to optimal levels for the second reactor, ensuring desired polymer properties while maintaining production continuity. This parameter control resolves the contradiction between maintaining production flow and controlling substance quantity.
2Manufacturing precision
If a separation system is added between reactors to remove chain transfer agents, then polymer properties are optimized, but the device complexity increases
Solution Approach 1:
The patent introduces a separation system as an intermediary component between the first and second reactors. This mediator removes chain transfer agents from the slurry stream, enabling precise control over polymer properties in the second reactor. The intermediary system resolves the contradiction by providing the necessary separation function to achieve manufacturing precision while maintaining a modular, manageable system architecture.
3Productivity
If chain transfer agent concentration is maintained high in the second reactor, then polymerization rate increases, but molecular weight of the polymer decreases
Solution Approach 1:
The patent applies preliminary action by removing chain transfer agents from the slurry before it enters the second reactor. This pre-treatment ensures that the second reactor receives slurry with controlled, lower hydrogen content, which allows for optimal molecular weight development. The preliminary removal of chain transfer agents prevents excessive chain termination, thereby maintaining high molecular weight while still enabling continuous production.
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 the production of multimodal polyolefins with desired molecular weight distributions by reducing chain transfer agent carryover, enhancing polymer properties and reactor efficiency.
Implementation Method 1
the diluent separator is a hydrocyclone
Data Source
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AI summary
A system and method for polymerizing olefin in the presence of a chain transfer agent in a first reactor to form a first polyolefin, discharging from the first reactor a transfer slurry having the first polyolefin and the chain transfer agent, and processing the transfer slurry in a separator to remove chain transfer agent and to provide a fluff slurry having the first polyolefin and a lower content of chain transfer agent than in the transfer slurry. The system and method provide for feeding the fluff slurry to a second reactor, polymerizing olefin in the second reactor to form a second polyolefin, and discharging from the second reactor a slurry having the second polyolefin.