On-line Drying Hollow Fiber Membranes Two-Stage Process
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Solution Overview
Problem
Existing processes for drying permselective hollow fiber membranes often result in uneven pore size distribution and reduced selectivity, which are critical for applications like hemodialysis and hemofiltration.
Innovation Solution
A continuous two-stage drying and tempering treatment process for hollow fiber membranes, involving initial drying at temperatures between 210 to 280°C for 1 to 4 seconds, followed by tempering at 180 to 200°C for 2 to 5 seconds, to achieve a narrow pore size distribution and high selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single-stage drying is used, then the drying process is simple and fast, but the pore size distribution is wide and selectivity is reduced
Solution Approach 1:
The drying process is divided into two distinct stages: a first drying stage at higher temperature (200-300°C) to rapidly remove bulk moisture, followed by a second drying stage at lower temperature (100-200°C) to refine the pore structure. This segmentation allows each stage to optimize for its specific function, achieving both high productivity and narrow pore size distribution.
Solution Approach 2:
The two drying stages are implemented in continuous sequence without interruption, maintaining the membrane in a controlled environment throughout the process. This continuous action ensures that the pore structure development is uninterrupted and consistently produces narrow pore size distribution while maintaining high drying efficiency.
2Productivity
If high temperature drying is used, then drying efficiency is high, but pore structure uniformity deteriorates
Solution Approach 1:
The temperature profile is segmented into two zones: the first drying stage uses high temperature (200-300°C) for rapid moisture removal with high drying efficiency, while the second drying stage uses lower temperature (100-200°C) to stabilize and uniformize the pore structure. This temporal segmentation of temperature conditions resolves the contradiction between drying efficiency and pore structure uniformity.
Solution Approach 2:
The temperature parameter is dynamically changed throughout the drying process. The process starts with high temperature to maximize drying efficiency, then transitions to lower temperature to refine and uniformize the pore structure. This parameter change strategy allows the system to achieve both high productivity and stable pore structure composition.
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
The two-stage drying and tempering process effectively narrows the pore size distribution and enhances the selectivity of the hollow fiber membranes, improving their performance in applications such as hemodialysis and hemofiltration.
Implementation Method 1
The devices comprise a plurality of rollers having a hot surface
Implementation Method 2
A continuous two-stage drying and tempering treatment process for hollow fiber membranes
Data Source
AI summary
The present invention relates to a continuous process for preparing permselective hollow fiber membranes being suitable e.g. for hemodialysis, hemodiafiltration and hemofiltration of blood which comprises a two-stage drying and tempering treatment of the hollow fiber membranes. According to a further aspect, the invention relates to a continuous process for drying permselective hollow fiber membranes on-line. The invention also relates to devices for on-line drying of permselective hollow fiber membranes.