Tapered Fiber Separation Membrane Element for Clogging Resistance
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Solution Overview
Problem
Existing separation membrane elements face challenges in balancing the reduction of flow resistance in the supply-side channel with the suppression of concentration polarization, while also preventing clogging of the supply water inflow end surface and the internal channel.
Innovation Solution
The separation membrane element incorporates a supply-side channel member with a net shape, featuring fibrous rows that intersect sterically to form intersections. The fibrous objects have tapered fibers with a large diameter portion and a small diameter portion, and a thread that is thinner at the central portion than at the large diameter portion, optimizing the supply-side channel area ratio and reducing flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the supply-side channel member is decreased to reduce concentration polarization layer thickness, then concentration polarization is suppressed, but fouling substances clog the supply-side channel and pressure loss increases
Solution Approach 1:
The supply-side channel member incorporates fibrous objects with different diameter characteristics at different locations: larger diameter portions near intersections to prevent clogging, and thinner central portions to maintain low flow resistance. This local variation in fiber diameter optimizes both anti-clogging performance and flow characteristics.
Solution Approach 2:
The supply-side channel member is constructed as a porous net-like structure comprising fibrous objects arranged in fibrous rows. This porous configuration allows fluid passage while providing mechanical support, balancing the needs for low flow resistance and resistance to clogging by fouling substances.
2Productivity
If the thickness of the supply-side channel member is decreased to improve separation performance, then concentration polarization is reduced, but the element requires more power and suffers damage
Solution Approach 1:
The invention optimizes the supply-side channel area ratio parameter to within 45-65% by controlling the arrangement and dimensions of fibrous objects. This parameter optimization achieves the right balance between maintaining adequate flow area (reducing pressure loss and power consumption) and providing sufficient structural support (preventing element damage).
3Loss of energy
If the supply-side channel area ratio is optimized to reduce flow resistance, then pressure loss decreases, but concentration polarization may increase
Solution Approach 1:
The fibrous objects exhibit local quality variations with larger diameters at intersection portions and smaller diameters at central portions. This creates a gradient structure that locally optimizes flow characteristics - larger intersections maintain open flow paths reducing pressure loss, while thinner central sections allow closer spacing to membranes reducing concentration polarization.
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 design effectively lowers concentration polarization and differential pressure increase due to clogging, enhancing the operational stability of the separation membrane element. It also increases the area of membranes packed per element, leading to higher water production rates and reduced risk of membrane damage.
Implementation Method 1
a supply-side channel area ratio is in a range of 45% to 65%, wherein the supply-side channel area ratio in % is given by A1/A2×100
Implementation Method 2
Separation membranes used for the separation method using a separation membrane element are classified, according to the hole diameter and separation function, into a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, and a forward osmosis membrane
Implementation Method 3
A reduction in element performance due to such concentration polarization can be suppressed by, for example, decreasing the thickness of a concentration polarization layer formed on the membrane surface
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(c)
AI summary
A separation membrane element according to the present invention comprises a water collecting tube, a separation membrane, a supply-side channel member, and a permeation-side channel member. The supply-side channel member has a net shape in which a plurality of fibrous rows X formed from a fibrous substance A, and a plurality of fibrous rows Y formed from a fibrous substance B, three-dimensionally intersect each other to form intersection points. The fibrous substance A and/or the fibrous substance B has a large diameter section and a small diameter section along a longitudinal direction, and in a longitudinal cross-section along the longitudinal direction, the fibrous substance A and/or the fibrous substance B is constituted by threads for which a center section between intersection point parts of the fibrous rows X and the fibrous rows Y has a smaller diameter than the large diameter section. The area percentage of the supply-side channel is 45-65%, and when observed in the thickness direction from the plane of the supply-side channel member, fibers between an arbitrary intersection point and an adjacent intersection point are tapered fibers for which the diameter expands in a tapered shape from one intersection point towards the other intersection point.