Helically Wound Hollow Fiber Membrane Module Design
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Solution Overview
Problem
Existing hollow fiber membrane modules for gas separation and dehydration face issues with maldistribution of sweep gas and structural integrity due to uniform fiber length requirements and wind angle constraints, leading to performance losses and increased costs.
Innovation Solution
A helically wound hollow fiber membrane module design that allows for significant variation in fiber length and increases the wind angle near the tubesheet region, reducing the fiber bundle diameter and packing fraction, which improves gas penetration and structural integrity without requiring uniform fiber lengths or embedding impervious wraps in the tubesheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform fiber length is used in helically wound membrane modules, then manufacturing and assembly is simplified, but sweep gas maldistribution occurs and performance is reduced
Solution Approach 1:
The patent applies local quality by allowing fiber length to vary in different regions of the module. Fibers near the tubesheet are shorter while fibers in the active region maintain optimal length for performance. This regional variation resolves the contradiction by optimizing local flow distribution without compromising overall manufacturing feasibility.
Solution Approach 2:
The patent introduces dynamic fiber length configuration where the effective fiber length varies along the axial direction of the module. This dynamic approach allows the module to adapt sweep gas flow distribution dynamically, improving performance while maintaining reasonable manufacturing processes through controlled fiber placement.
2Reliability
If impervious wraps are embedded in the tubesheet to seal fiber bundles, then gas leakage is prevented, but tubesheet structural integrity is reduced
Solution Approach 1:
The patent extracts the impervious wrap from the tubesheet interior and relocates it to the exterior surface or eliminates it entirely by using alternative sealing methods at the fiber bundle periphery. This removal prevents the wrap from creating discontinuities that weaken the tubesheet, while sealing effectiveness is maintained through the alternative configuration.
Solution Approach 2:
The patent introduces an intermediary sealing mechanism that does not require embedding impervious material in the tubesheet. This could be a peripheral seal, clamp, or bonding method that achieves the same sealing function without compromising the tubesheet's structural continuity and strength.
3Strength
If fiber bundle diameter is reduced in the tubesheet region, then structural integrity improves, but fiber packing density decreases
Solution Approach 1:
The patent segments the fiber bundle into different radial zones with different packing densities. The inner region near the tubesheet has reduced density to preserve structural integrity, while the outer active region maintains high packing density for optimal performance. This segmentation resolves the contradiction by allowing both regions to operate at their optimal densities.
Solution Approach 2:
The patent applies local quality by creating a radial gradient in fiber packing density. The packing fraction varies from lower values near the tubesheet (where structural integrity is prioritized) to higher values in the active region (where mass transfer performance is prioritized). This spatially varying quality resolves the contradiction between structural and performance requirements.
4Ease of operation
If wind angle is increased near the tubesheet, then gas penetration and structural integrity improve, but fiber length uniformity is compromised
Solution Approach 1:
The patent introduces a dynamic wind angle profile that varies along the axial length of the module. The wind angle is increased in the tubesheet region to improve gas penetration and structural integrity, then transitions to a standard angle in the active region. This dynamic variation is achieved through controlled fiber placement during manufacturing, balancing structural and operational requirements.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the fiber bundle with a specific wind angle profile before module assembly. The fibers are arranged with increased wind angle near the tubesheet during the winding process, ensuring optimal gas penetration and structural integrity are built-in from the start, while maintaining controllable manufacturing precision through established winding techniques.
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 module design maintains performance with varying fiber lengths and enhances structural integrity and gas penetration, reducing costs and operational losses associated with maldistribution and pressure drops.
Implementation Method 1
moisture diffuses across the water permeable membranes to the shell side of the module
Implementation Method 2
moisture diffuses across the water permeable membranes
Implementation Method 3
a dry gas is injected on the shell side of the module to sweep away the water vapor that has permeated
Data Source
Figure 1~3
Figure 2~3A
Figure 4
AI summary
A helically wound hollow membrane module having a core.with a plurality of helically wound layers of semi-permeable hollow fibers wound on the core. The fiber wind angle with respect to any one layer of fibers may be essentially constant along the axial length of the module, except in one or both end or tubesheet regions, where the wind angle may be increased, in at least some of the layers relative to the essentially constant wind angle, to produce an area of decreasing diameter.