Tapered Spiral-Wound Cross-Flow Filter Element
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Solution Overview
Problem
Spiral-wound cross-flow filter elements with pleated and welded membranes experience reduced retentate fluid velocity due to increased permeate flux, leading to fouling and decreased operational life, as the constant area for feed/retentate flow results in decreased fluid velocity, which is less effective at dislodging retentate materials.
Innovation Solution
The use of tapered pleated and spiral-wound cross-flow filter elements, where each leaf's inlet edge is longer than the outlet edge, creates a decreasing area for feed/retentate flow, maintaining fluid velocity and preventing fouling while maintaining high permeate flux capacity by compensating for permeate flux-induced volumetric flowrate decreases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the filter element is designed with pleated and welded membranes to increase permeate flux capacity, then the permeate flux rate is improved, but the retentate fluid velocity decreases leading to fouling and reduced operational life
Solution Approach 1:
The filter element employs different geometric characteristics at different locations: the pleated membrane provides high flux capacity while the tapered configuration (decreasing area from inlet to outlet) maintains retentate velocity. This local differentiation allows each region to optimize for its specific function - the pleats maximize permeate production while the taper prevents fouling by maintaining cleaning velocity throughout the element length.
Solution Approach 2:
The invention changes the geometric parameter of the flow channel area along the length of the filter element. By tapering the element so that the cross-sectional area for retentate flow decreases from inlet to outlet, the linear velocity of the retentate is maintained constant or increased despite the decreasing volumetric flow rate. This parameter change (area reduction) compensates for the volume loss to permeate and prevents velocity degradation that would cause fouling.
2Device complexity
If the filter element maintains a constant area for feed/retentate flow, then the structural design is simplified, but the fluid velocity decreases due to permeate flux-induced volumetric flowrate decreases, resulting in fouling
Solution Approach 1:
The invention changes the geometric parameter of the flow channel area along the length of the filter element. By tapering the element so that the cross-sectional area for retentate flow decreases from inlet to outlet, the linear velocity of the retentate is maintained constant or increased despite the decreasing volumetric flow rate. This parameter change (area reduction) compensates for the volume loss to permeate and prevents velocity degradation that would cause fouling.
3Reliability
If the filter element is designed with tapered pleated and spiral-wound structure, then the fluid velocity is maintained and fouling is prevented, but the manufacturing complexity increases
Solution Approach 1:
The filter element is constructed by spiral-winding pleated membrane sheets around a permeate collection tube. This segmentation approach allows the tapered geometry to be achieved through repeated winding of pre-pleated membrane segments, rather than requiring complex monolithic tapering. The modular nature of spiral winding simplifies manufacturing while achieving the desired tapered configuration for velocity maintenance.
Solution Approach 2:
The spiral-wound configuration inherently creates a curved, three-dimensional tapered structure that maintains the required geometry through its winding pattern. This curved construction method is more manufacturable than attempting to create sharp angular tapers, as the spiral winding naturally produces smooth transitions and can be fabricated using standard卷绕 (winding) equipment.
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 tapered design maintains effective membrane cleaning and fouling prevention while sustaining increased permeate flux rates, ensuring longer operational life and industrial usability by controlling fluid velocity and pressure differences across the filtration membrane.
Implementation Method 1
Particles, solutes, or other materials which are smaller than the filtration membrane pore size pass through the membrane as filtrate in the portion of the feed fluid that forms the permeate stream
Implementation Method 2
In cross-flow filtration, the feed fluid to be filtered flows in a direction generally parallel to the surface of a semi-permeable membrane - i.e., tangentially to the filtration membrane
Implementation Method 3
the tangential motion of the bulk fluid across the filtration membrane can mechanically dislodge retentate materials from the membrane surface
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Pleated, tapered, and spiral-wound cross-flow filter elements (100) are described. The filter elements have pleated and tapered membrane leaves (110). The pleated and tapered membrane leaves maintain retentate fluid velocity in high permeate flux applications.