Spiral Membrane Element Deformation Control
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Solution Overview
Problem
Conventional spiral membrane elements with thinner composite semi-permeable membranes experience deformation-induced decreases in rejection, limiting their effective membrane area and permeate flow rate due to the use of low-pressure permeation-side flow path materials.
Innovation Solution
A spiral membrane element design featuring a composite semi-permeable membrane with a porous support of 80-100 µm thickness and a permeation-side flow path material made of reinforced tricot knit fabric with continuous linear grooves of 0.05-0.40 mm width, which enhances membrane stability and resistance to deformation, thereby maintaining high rejection and permeate flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a thinner composite semi-permeable membrane is used to increase the effective membrane area, then the membrane area increases, but the membrane deformation increases causing rejection decrease
Solution Approach 1:
The support structure is segmented into multiple rigid spacers positioned at intervals along the membrane element. These spacers divide the membrane into supported segments, preventing overall deformation while maintaining large membrane area. The segmentation allows the thin membrane to be stabilized at multiple points without requiring a thick continuous support structure.
Solution Approach 2:
Rigid spacers act as intermediary elements between the thin composite semi-permeable membrane and the permeate collection system. These spacers provide mechanical support and maintain the membrane's structural integrity, preventing deformation-induced rejection decrease while allowing the membrane to remain thin for increased effective area.
2Device complexity
If a conventional permeation-side flow path material is used for low-pressure applications, then the structure is simpler, but the membrane deformation increases
Solution Approach 1:
The rigid spacers change the mechanical parameters of the membrane support system by introducing high-stiffness elements at strategic positions. This parameter change provides sufficient structural support to prevent membrane deformation without requiring a complete redesign of the flow path material, thus maintaining relative structural simplicity while improving membrane stability.
3Area of stationary object
If the membrane thickness is reduced to increase effective area, then the membrane area increases, but the pressure loss increases
Solution Approach 1:
The solution moves from a two-dimensional planar support approach to a three-dimensional structured support system using rigid spacers. These spacers create vertical support structures that maintain membrane flatness and reduce flow path resistance, thereby decreasing pressure loss while allowing the membrane to be thinner for increased effective area.
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 design increases the effective membrane area and permeate flow rate while preventing deformation-induced rejection decreases, improving treatment efficiency and throughput in water desalination and wastewater treatment processes.
Implementation Method 1
a membrane method using a composite semi-permeable membrane has been found to be effective for such water treatment
Implementation Method 2
A permeated liquid 8 also passes through the composite semi-permeable membranes 2 during the process of allowing the supplied liquid 7 to flow along the supply-side flow path material 6
Data Source
Figure 1
Figure 2A~2I
Figure 3
AI summary
The purpose of the present invention is to provide a spiral membrane element in which the effective membrane area of a composite semi-permeable membrane can be increased and any decrease in rejection rate due to deformation of the composite semi-permeable membrane is less likely to occur. The spiral membrane element is provided with: a laminate including a permeation-side flow path material 3, a supply-side flow path material 6, and a composite semi-permeable membrane 2 having a separation function layer on a surface of a porous support; a perforated central tube 5 around which the laminate is wound; and a sealing member 21 for preventing mixing between the supply-side flow path and a permeation-side flow path, the spiral membrane element being characterized in that the thickness of the porous support of the composite semi-permeable membrane 2 is 80 µm to 100 µm, the permeation-side flow path material 3 is formed from a tricot knit fabric, and the width of a groove that continues in a straight line is 0.05 mm to 0.40 mm.