Tubular Polymerization Reactor with Rotatable Scraper for Molecular Weight Control
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Solution Overview
Problem
Existing reactors face difficulties in monitoring and controlling reaction conditions for continuous polymerization, particularly in setting desired molecular weight distribution, and struggle with incomplete or inhomogeneous product withdrawal, especially with viscoelastic materials like synthetic rubbers.
Innovation Solution
A tubular reactor design with a rotatable scraper or wiper mechanism and stators to enhance mixing and heat transfer, allowing for controlled residence time and molecular weight distribution by influencing reaction conditions through adjustable scraper angles, outlet configurations, and axial velocities, which also prevents polymer deposit formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a tubular reactor housing is used for continuous polymerization, then the reactor structure is simple and heat transfer is efficient, but the reaction conditions cannot be monitored and influenced with sufficient precision, particularly molecular weight distribution control
Solution Approach 1:
The patent introduces a rotatable scraper or wiper mechanism with adjustable angles and positions within the tubular reactor. This dynamic element allows continuous adjustment of the residence time distribution of the polymerization reaction mixture, enabling precise control of molecular weight distribution while maintaining the simplicity of the tubular reactor structure. The scraper's rotation speed and angle can be varied to optimize reaction conditions differentially along the reactor length.
2Temperature
If a heat exchanger with scraper blades is used, then heat transfer is improved, but product withdrawal becomes incomplete or inhomogeneous, especially for viscoelastic materials
Solution Approach 1:
The patent divides the reactor into multiple zones with different scraper configurations. Each zone has scrapers with specific angles and positions optimized for local conditions. The outlet is designed with a specific configuration that works in conjunction with the segmented scraper system to ensure complete and homogeneous product withdrawal. This segmentation allows the heat exchanger to maintain efficient heat transfer while the distributed scraper system ensures uniform product removal throughout the reactor.
3Temperature
If scraper blades contact the reactor housing interior to prevent polymer deposits, then heat transfer efficiency is maintained, but mechanical forces on scrapers increase, reducing their lifetime
Solution Approach 1:
The patent employs scrapers with adjustable angles and positions that can be dynamically optimized. The scraper blades are designed to contact the reactor housing at specific angles (e.g., 30-60 degrees) that balance effective polymer deposit removal with reduced mechanical wear. The rotatable nature of the scrapers allows them to be repositioned or have their angles adjusted during operation, extending their service life while maintaining heat transfer efficiency by preventing polymer buildup on the reactor walls.
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
Enables more precise control over reaction conditions, prevents polymer deposit formation, and ensures homogeneous product withdrawal, achieving a desired molecular weight distribution with reduced scatter and improved heat transfer efficiency.
Implementation Method 1
the scraper or wiper has at least one scraper or wiper blade to run along an interior side of the reactor housing
Implementation Method 2
For the purposes of the invention, an eccentric shaft is, for example, a shaft which has a cage mounted so as to be rotatable about the geometric central axis of the reactor
Implementation Method 3
good heat transfer is ensured from the reaction medium through the reactor housing to the cooling medium
Data Source
AI summary
The present invention relates to a reactor (10) and a process for continuous polymerization, where the reactor (10) has an essentially tubular reactor housing (16). The reactor housing (16) has a drive (38) which runs along the geometric central axis (12) in the flow direction (22) and is configured as a central shaft. A rotatably arranged scraper or wiper (36) is provided within the reactor housing (16); the scraper or wiper (36) has at least one scraper or wiper blade (42) to run along an interior side (44) of the reactor housing (16). The rotational movement of the scraper or wiper (36) results in radial mixing of a stream within the reactor housing (16) which dominates gravity effects and, by virtue of shaping of the scrapers or wipers, optionally makes plug flow or a loop flow or backflow within the reactor (10) or else via an additional external pumped circulation system (23) possible. This allows the reaction conditions in the axial direction of the reactor housing (16) to be predicted and individually suitable reaction conditions to be set and controlled along the reactor housing, so that, in particular, a desired molecular weight distribution can be set.