Polymerization Reactor Draft Tube Helical Stirrer Mixing
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Solution Overview
Problem
Polymerization reactors face challenges in achieving efficient mixing, heat control, and maintaining a single phase during solution polymerization reactions, particularly due to high viscosity and the need for specific temperature and concentration gradients to optimize polymer properties.
Innovation Solution
A polymerization reactor design featuring a draft tube with a helical ribbon stirrer that creates distinct sections within the reactor, allowing for controlled flow and interconnection of components to achieve rapid homogenization, adjustable temperature and concentration gradients, and improved heat control, ensuring a single liquid phase and tailored polymer properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple separately driven mixing devices are used to achieve rapid mixing and homogeneity, then mixing efficiency is improved, but device complexity, costs, and downtime probability increase
Solution Approach 1:
The patent combines multiple mixing functions into a single integrated mixing device that performs both axial and radial mixing actions. This unified device replaces what would traditionally require multiple separate mixing devices, thereby reducing mechanical complexity while maintaining effective mixing performance through combined flow patterns.
Solution Approach 2:
The mixing device is designed to perform multiple mixing functions simultaneously - creating axial circulation for bulk mixing and radial flow for local homogeneity. This multi-functional approach allows one device to accomplish what would otherwise require several specialized devices, reducing overall system complexity.
2Temperature
If higher reactor temperature is used to maintain components above precipitation temperature, then mixing and heat removal is improved, but low molecular weight polymer formation increases
Solution Approach 1:
The patent creates distinct thermal zones within the reactor by using the draft tube and mixing device to establish localized circulation patterns. This allows different regions of the reactor to maintain different temperatures - the bulk can be kept at higher temperatures for good mixing and heat removal, while localized cooler zones prevent excessive polymer degradation and low molecular weight formation.
Solution Approach 2:
The reactor is segmented into different flow and thermal zones using the draft tube structure. The draft tube creates a separate circulation path that allows temperature stratification, enabling the system to maintain higher overall temperatures for mixing while creating controlled cooler regions where polymerization occurs without excessive heat exposure.
3Productivity
If conventional mixing devices are used to control flow patterns, then mixing is improved, but heat control capability is insufficient
Solution Approach 1:
The patent merges mixing function and heat transfer function into a single integrated system. The draft tube and mixing device work together to simultaneously achieve flow control for mixing and create thermal circulation patterns for heat removal, eliminating the need for separate heat control mechanisms.
Solution Approach 2:
The system uses fluid circulation patterns created by the mixing device within the draft tube to achieve heat transfer. The circulating fluid acts as a heat carrier, using hydraulic flow patterns to remove heat from the polymerization reaction zone, thereby combining mixing and heat control functions.
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 design enables rapid mixing, precise control of temperature and concentration gradients, and maintains a single phase, enhancing polymer homogeneity and properties, such as molecular weight distribution, while reducing complexity and costs by eliminating the need for separate mixing devices.
Implementation Method 1
a stirrer (12) comprising a top plate (13) located above the lower opening (11) of the draft tube (6), a stirrer blade (14) having a helical shape, which surrounds the draft tube (6)
Implementation Method 2
The advantages of such an assembly are that the mixing between higher temperature bulk solution and lower temperature reactants introduced into the reactor is enhanced
Implementation Method 3
Mixing can occur within the reactor already by convection of the differently heated parts of the polymerization components
Data Source
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AI summary
The present invention relates to a polymerization reactor assembly, comprising a reactor having a housing and an inner space, the reactor comprising at least one inlet, at least one outlet, a draft tube having a substantially cylindrical shape and an inner space, wherein the draft tube is located within the inner space of the reactor so that an upper opening and a lower opening of the draft tube are fluidly connected with the inner space of the reactor, and a stirrer comprising a top plate located above the lower opening of the draft tube, a stirrer blade having a helical shape, which surrounds the draft tube, wherein the axis of the draft tube and the axis of the stirrer blade are coinciding, the stirrer blade extending concentrically with respect to the draft tube and the housing of the reactor, and a bottom plate located below the lower opening of the draft tube, wherein the inner space of the reactor comprises sections A, B, C, and D, wherein section A is the space defined by the housing of the reactor and an upper surface of the top plate, section B is the space defined by the housing of the reactor, the draft tube, a lower surface of the top plate and an upper surface of the bottom plate, section C is the space defined by the housing of the reactor and a lower surface of the bottom plate, and section D is the inner space of the draft tube, wherein the top plate has at least one first opening fluidly connecting section A and section B, wherein the bottom plate has at least one first opening fluidly connecting section B and section C, wherein the bottom plate has at least one second opening fluidly connecting section C and section D, and wherein the stirrer is rotatable around the draft tube and inside the housing of the reactor. The present invention further relates to a process for polymerization of at least one alpha-olefin monomer using the above reactor assembly.