Loop Reactor Elbow Design for Continuous Polymerization
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Solution Overview
Problem
The use of multiple settling legs in loop reactors for olefin polymerization leads to inefficiencies due to batch product recovery, interference with slurry circulation, frequent maintenance needs, and increased footprint, which reduces production efficiency and increases costs.
Innovation Solution
A loop reactor system with vertical and elbow sections configured to maintain a high Dean number and circulation velocity, allowing for continuous slurry withdrawal and reduced reactor footprint, incorporating continuous take-off assemblies to enhance production efficiency and reduce land use and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple settling legs are used for product recovery, then production capacity is increased, but batch operation interference with slurry circulation occurs
Solution Approach 1:
The patent replaces batch settling leg operation with continuous product withdrawal through a continuous take-off assembly. The slurry flows continuously through the loop reactor and is continuously withdrawn at a designated point, eliminating the periodic interruption caused by batch settling operations while maintaining high production capacity.
Solution Approach 2:
The patent extracts the product withdrawal function from the settling leg system and implements it through a dedicated continuous take-off assembly. This separates the circulation function (maintained in the loop reactor) from the product recovery function (performed at the take-off point), allowing both to operate optimally without interference.
2Productivity
If multiple settling legs are used, then more polymer can be recovered, but valve mechanisms require frequent seal-off and maintenance
Solution Approach 1:
The patent removes the complex valve mechanisms from the product recovery system by replacing settling legs with a continuous take-off assembly. This eliminates the need for frequent valve seal-off operations while maintaining efficient polymer recovery through continuous flow withdrawal.
Solution Approach 2:
The continuous take-off assembly enables uninterrupted product withdrawal without the periodic valve operations required by settling legs. The system maintains continuous slurry flow and continuous product recovery, eliminating the cyclical valve opening/closing operations that compromise seal integrity.
3Productivity
If loop reactor size is increased for higher capacity, then production volume increases, but settling legs cannot be increased in size and more legs are needed
Solution Approach 1:
The continuous take-off assembly serves as a universal product withdrawal mechanism that scales with reactor size. Instead of adding more settling legs as reactor capacity increases, the same continuous withdrawal principle applies to larger reactors, maintaining simplicity while accommodating higher production volumes.
Solution Approach 2:
The continuous take-off system provides a scalable solution where product withdrawal rate can be increased with reactor size without adding discrete settling leg units. The continuous flow nature allows proportional scaling of production capacity with reactor volume while maintaining the same fundamental withdrawal mechanism.
4Quantity of substance
If settling legs are used for product recovery, then polymer can be concentrated, but reactor footprint increases and land cost increases
Solution Approach 1:
The patent transitions from horizontal settling leg arrangements (increasing footprint) to a vertical loop reactor configuration with continuous take-off. The loop reactor utilizes vertical space and continuous flow dynamics to achieve concentration without requiring additional horizontal land area for multiple settling leg units.
Solution Approach 2:
The continuous take-off assembly concentrates polymer through continuous withdrawal and settling in a controlled manner, eliminating the need for multiple discrete settling legs that would increase footprint. The continuous operation allows efficient concentration within the compact loop reactor configuration.
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 configuration improves production efficiency by maintaining high slurry concentration and flow rate, reducing reactor footprint, and lowering capital costs while maintaining high processing capacity.
Implementation Method 1
at least one elbow section having an internal diameter (d) and a radius (Rc) of an inner curvature, wherein the at least one elbow section is configured to maintain a Dean number (Dn) of the slurry flowing therein to be higher than 3,000,000
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A reactor system containing one or more loop reactors for olefin polymerization is provided. The loop reactors include vertical sections, elbow sections, and/or horizontal sections connected into one or more loop reaction zones to polymerize an olefin monomer in the presence of a liquid diluent into a slurry comprising particles of a polyolefin polymer. The reactor system footprint is reduced to increase production efficiency and save cost, while maintaining a high processing capacity. In one embodiment a horizontal length (LH) of at least one horizontal section is greatly reduced with maintained processing capacity. In another embodiment, at least one elbow section of the reactor system is configured to maintain a Dean number (Dn) of the slurry flowing therein to be higher than 3,000,000.