Continuous Spinning Solution Mixing via Multiple Screw Extruder
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Solution Overview
Problem
The conventional batch process for preparing spinning solutions for dialysis membranes is time-consuming and inflexible, requiring extended mixing times and preventing rapid changes in solution composition during membrane production.
Innovation Solution
A continuous process using a multiple screw extruder to mix hydrophobic and hydrophilic polymers with a solvent and optional non-solvent, forming a homogeneous spinning solution, allowing for rapid production and flexibility in composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional batch process is used to prepare spinning solutions, then the mixing can be performed in a simple vessel, but the processing time is extended to 2-3 hours and rapid composition changes are prevented
Solution Approach 1:
The patent implements a continuous processing system where polymer granules, solvent, and additives are continuously fed into an extruder that maintains constant mixing and processing. This eliminates the batch-to-batch interruptions and extends the useful action continuously, reducing total processing time from hours to minutes while maintaining homogeneous mixing through continuous mechanical action in the extruder zones.
Solution Approach 2:
The extruder system allows dynamic adjustment of processing parameters including screw speed, temperature zones, and feed rates during operation. This enables rapid composition changes by simply adjusting the feed composition or processing conditions without waiting for batch completion, providing real-time flexibility that static batch vessels cannot achieve.
2Adaptability or versatility
If a batch process is used, then equipment simplicity is maintained, but flexibility to change solution composition is lost
Solution Approach 1:
The continuous process segments the mixing function across multiple extruder zones with different temperature and shear conditions, allowing different components to be introduced at different stages. This segmentation enables flexible composition control while distributing the complexity across standardized extruder components rather than requiring a completely new complex system.
Solution Approach 2:
The extruder serves multiple functions simultaneously: feeding, melting, mixing, degassing, and pumping the spinning solution. This multi-functionality consolidates what would otherwise require multiple separate pieces of equipment into a single device, making the increased adaptability achievable without proportionally increasing overall system complexity.
3Productivity
If multiple separate units are used for mixing and degassing, then each unit can be optimized for its specific function, but the overall process time is extended
Solution Approach 1:
The patent merges mixing and degassing functions into a single integrated extruder system. The extruder combines mechanical mixing zones with vacuum degassing zones in sequence, allowing both functions to be performed continuously in one device rather than requiring separate batch mixing vessels followed by separate degassing units, thereby reducing total process time while maintaining functional optimization.
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 fast and flexible production of spinning solutions for dialysis membranes, reducing processing time and enabling real-time adjustments to solution composition, resulting in a homogeneous and efficient output.
Implementation Method 1
DE 4027888 A1 discloses a process for the continuous dissolution of gelatine wherein gelatine powder and a solvent are continuously fed to a screw extruder and mixed by applying shear force at elevated temperature and pressure
Implementation Method 2
DE 4027888 A1 discloses a process for the continuous dissolution of gelatine wherein gelatine powder and a solvent are continuously fed to a screw extruder and mixed by applying shear force at elevated temperature and pressure
Implementation Method 3
DE 4027888 A1 discloses a process for the continuous dissolution of gelatine wherein gelatine powder and a solvent are continuously fed to a screw extruder and mixed by applying shear force at elevated temperature and pressure
Data Source
AI summary
The present disclosure relates to a continuous process for preparing a spinning solution for dialysis membranes which involves a multiple screw extruder.