Membrane Separation Device with Bidirectional Flow for Fouling Prevention
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Solution Overview
Problem
Spiral-wound membrane elements in separation devices face fouling issues, particularly at the front end due to high permeation flux and osmotic pressure, leading to reduced performance and difficulty in removing deposited foulants, especially when pretreatment is insufficient.
Innovation Solution
A membrane separation device with a configuration that allows the stream-to-be-treated to be fed in both forward and reverse directions, using a cylindrical pressure vessel with anti-telescoping plates and sealing materials to facilitate movement of separation membrane elements, and a mechanism to switch flow direction between subunits, ensuring balanced membrane use and effective fouling prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a stream-to-be-treated is fed to a spiral-wound membrane element in a single direction, then the membrane structure provides uniform channel distribution, but foulants deposit on the front end surface leading to fouling and reduced performance
Solution Approach 1:
The patent enables bidirectional feeding of the stream-to-be-treated through the spiral-wound membrane element by providing sealing members at both end surfaces. The flow direction can be reversed periodically to prevent foulant accumulation at the front end, thereby resolving the contradiction between maintaining uniform channel distribution and preventing fouling.
Solution Approach 2:
The patent implements periodic reversal of the feed direction through the membrane element. By alternating the flow direction at regular intervals, foulants that would normally accumulate at the front end are prevented from depositing, while the uniform channel distribution is maintained during each feeding phase.
2Productivity
If multiple separation membrane elements are disposed in series in a single pressure vessel, then treatment capacity is increased, but fouling occurs dominantly in the front end region of the first element due to high permeation flux and osmotic pressure
Solution Approach 1:
The patent allows reversal of the feed direction through the series-connected membrane elements. By periodically reversing the flow, the front end region that experiences high fouling tendency can be flushed by changing the flow direction, thereby maintaining treatment capacity while reducing fouling accumulation.
Solution Approach 2:
The patent changes the operational parameter of flow direction periodically. By reversing the feed direction, the hydraulic conditions at the front end region are altered, preventing fouling while maintaining the series configuration for high productivity.
3Stability of the object's composition
If conventional sealing materials are used in a cylindrical pressure vessel, then the membrane elements are constrained in one direction, but they cannot move substantially in either direction for bidirectional feeding
Solution Approach 1:
The patent introduces movable sealing members that can accommodate bidirectional movement of the membrane elements. The sealing members are designed to maintain sealing effectiveness while allowing the membrane elements to move substantially in either direction within the pressure vessel, enabling flexible feed direction switching.
Solution Approach 2:
The patent divides the sealing function into multiple sealing members positioned at different locations. This segmentation allows each sealing member to handle specific directional constraints while collectively enabling bidirectional movement capability of the membrane elements.
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 configuration allows for efficient membrane separation while reducing fouling and maintenance time, ensuring the separation membranes operate at full performance with balanced use and effective fouling prevention.
Implementation Method 1
a solution containing a solute such as salt is allowed to permeate the reverse osmosis membrane at a pressure above the osmotic pressure of the solution
Implementation Method 2
reverse osmosis membrane, a nanofiltration membrane, an ultrafiltration membrane, a microfiltration membrane
Implementation Method 3
a backwashing process in which pressure is applied onto the permeate side of a membrane to move the permeate water backward toward the raw water side of the membrane
Data Source
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AI summary
The use of the separation membranes is allowed to be balanced, and a membrane separation process is allowed to be efficiently carried out while effectively preventing fouling, even if a subunit is constituted by separation membrane unit components that use spiral-wound membrane elements. A membrane separation device comprising a separation membrane unit A that comprises a separation membrane unit component 8, feed stream side lines F1 and F2, and a permeate stream line P, and a unit for feeding a stream-to-be-treated, wherein a stream-to-be-treated sealing material is provided in the perimeter of an anti-telescoping plate of the separation membrane element, wherein the separation membrane elements can be moved within a cylindrical pressure vessel substantially in either direction, wherein the separation membrane unit is configured to feed the stream-to-be-treated through one of the feed stream side lines F1 and F2 and to discharge the concentrate stream through the other of the feed stream side lines, and wherein the separation membrane unit includes a mechanism that can switch the flow between the feed stream side lines.