Batch Falling Strand Devolatilizer Design Method
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Solution Overview
Problem
Current devolatilization technologies, such as thin-film evaporators and devolatilizing extruders, are costly, inefficient, and unsuitable for small and medium enterprises due to high equipment and operating costs, mechanical complexity, and viscosity limitations, lacking a systematic scale-up design approach that integrates fluid mechanics, heat transfer, and mass transfer principles effectively.
Innovation Solution
A design method for batch falling strand devolatilizers that integrates a liquid-phase diffusion film or pool equation with a mass balance equation to optimize devolatilization efficiency, reducing costs and mechanical complexity by using batch or quasi-continuous processes with recycles, eliminating the need for entraining agents and mechanical rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thin-film evaporators or devolatilizing extruders are used, then devolatilization can be performed, but equipment cost and operating cost are high
Solution Approach 1:
The invention extracts and eliminates the mechanical rotation component from traditional devolatilizing extruders, using only static mixing elements and vacuum application. This removes the need for complex mechanical drive systems, significantly reducing equipment cost and maintenance requirements while maintaining devolatilization capability through the static mixing and vacuum removal process
Solution Approach 2:
The invention uses simple, replaceable static mixing elements instead of expensive, complex mechanical extruder components. These static elements can be easily manufactured and replaced if needed, reducing overall equipment investment and making the system more accessible to small and medium enterprises
2Productivity
If devolatilizing extruders with mechanical rotation are used, then mixing and devolatilization can be performed, but device complexity increases
Solution Approach 1:
The invention removes the mechanical rotation system entirely, retaining only the static mixing elements and vacuum system. This extraction of the mechanical component dramatically simplifies the device structure while maintaining productivity through the combined action of static mixing and vacuum-driven volatile removal
Solution Approach 2:
The invention replaces the mechanical rotation mixing system with a static mixing system driven by vacuum flow. The mixing action is achieved through the geometry of static elements that create turbulence and mixing as material passes through, substituting mechanical energy with vacuum-driven flow energy
3Reliability
If devolatilizing extruders are used, then devolatilization can be performed, but operating cost increases
Solution Approach 1:
By removing the mechanical rotation system, the invention eliminates the energy consumption associated with driving motors and mechanical mixers. The only energy input required is for the vacuum system, significantly reducing operating costs while maintaining devolatilization efficiency through the vacuum-driven process
Solution Approach 2:
The static mixing elements are designed to create self-mixing flow patterns that require no external energy input beyond the vacuum drive. The system uses the vacuum flow itself to create mixing action, making the process energy-efficient and reducing continuous operating costs
4Device complexity
If batch falling strand devolatilizer is designed without scale-up method, then simple structure can be maintained, but devolatilization efficiency is insufficient
Solution Approach 1:
The invention provides scale-up methods based on dimensionless numbers (Reynolds number, Froude number, Weber number) that allow systematic adjustment of operating parameters such as vacuum level, flow rate, and mixing element geometry. This enables efficient devolatilization across different scales while maintaining the simple batch falling strand structure
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 method simplifies the devolatilization process, reduces defective products, increases yield, and achieves high devolatilization efficiency by optimizing backmixing parameters and recycles, making it more cost-effective and adaptable for various polymer viscosities without the need for mechanical rotation or entraining agents.
Implementation Method 1
the polymer trickle falls by gravity into a vacuum
Implementation Method 2
falls by gravity into a vacuum
Implementation Method 3
devolatilization efficiency
Implementation Method 4
integrates a liquid-phase diffusion film or pool equation with a mass balance equation
Data Source
AI summary
A design method of batch falling strand devolatilizers is disclosed. The method includes following steps. Firstly, construct a database that contains data of batch falling strand devolatilizer vs. devolatilization of at least one kind of polymer. Then data in the database is substituted into a mass balance difference equation to get a backmixing parameter. When the backmixing parameter is zero or is approaching zero, a liquid diffusion stage efficiency equation having a film equation or a pool equation is integrated with the mass balance difference equation to get a devolatilization process efficiency equation. By optimizing of a theoretical value of the backmixing parameter, a theoretical value of the process efficiency from calculation of the devolatilization process efficiency equation approaches the value of the process efficiency. Then the theoretical value of the backmixing parameter is substituted into the devolatilization process efficiency equation for performing volume design of the batch falling strand devolatilizer.