Mixing-promoting spacer patterns for spiral-wound elements
Embodiments of the present invention provide for the deposition of spacing elements for spiral wound elements which promote mixing within the feed space during element operation thereby improving element performance and reducing concentration polarization and potential for biological fouling.
1. A membrane for use in a spiral wound permeable membrane system, comprising a membrane having spacing features deposited directly onto a surface of the membrane, wherein the spacing features are configured such that the features direct fluid flow along one or more tortuous paths, wherein the spacing features comprise a first plurality of spacing features that extend a first height above the surface of the membrane, and a second plurality of spacing features that extend a second height above the surface of the membrane, wherein the second height is less than the first height.
2. A membrane as in claim 1 , wherein the spacing features comprise a plurality of substantially parallel line segments disposed in an array wherein the line segments are oriented at an angle other than zero degrees to the direction of fluid flow in the permeable membrane system, the line segments are separated from each other by a first distance along a dimension perpendicular to the overall direction of fluid flow and by a second distance along a dimension parallel to the overall direction of fluid flow, and wherein the line segments are disposed to prevent fluid flow direct from inlet to outlet of the system.
3. A membrane as in claim 2 , wherein the line segments are 0.01″ to 0.03″ wide, 0.1″ to 0.3″ long, the first distance is 0.4″ to 0.7″, and the second distance is 0.4″ to 0.7″.
4. A membrane as in claim 3 , wherein the line segments are 0.02″ wide, 0.1875″ long, the first distance is 0.5625″, and the second distance is 0.5625″.
5. A membrane as in claim 1 , wherein the spacing features comprise a plurality of chevron shaped features, disposed in a two-dimensional array on the membrane, with each line of the array offset from adjacent lines such that fluid flowing between two chevrons in one line is turned by a chevron in a successive line.
6. A membrane as in claim 5 , wherein each feature is 0.01″ to 0.03″ in thickness, 0.08″ to 0.2″ in width, 0.1″ to 0.3″ in height, disposed with a gap of 0.4″ to 0.7″ between adjacent features in each line and line spaced 0.4″ to 0.7″ apart.
7. A membrane as in claim 6 , wherein each feature is 0.02″ in thickness, 0.0938″ in width, 0.1875″ in height, disposed with a gap of 0.5625″ between adjacent features in each line and line spaced 0.5625″ apart.
8. A membrane as in claim 1 , wherein the spacing features comprise a plurality of line segments, wherein a first subset of the line segments are oriented at a first angle to the direction from inlet to outlet, and wherein a second subset of the line segments are oriented at a second angle to the direction from inlet to outlet, and wherein the line segments are positioned such that fluid flow in a direction along a line segment in the first subset is redirected by a line segment in the second subset.
9. A membrane as in claim 8 , wherein the features are 0.01″ to 0.03″ in thickness, with equal length and height of 0.1″ to 0.3″.
10. A membrane as in claim 9 , wherein the first angle is 35° to 55° and the second angle is 125° to 145°.
11. A membrane as in claim 10 , wherein the features are separated by 0.4″ to 0.7″.
12. A membrane as in claim 11 , wherein the features are separated by 0.5625″.
13. A membrane as in claim 9 , wherein the first angle is 12.5° to 32.5° and the second angle is 147.5° to 167.5°.
14. A membrane as in claim 1 , wherein the features are separated by 0.19″ to 0.39″.
15. A membrane as in claim 1 , wherein the second height is no more than one half the first height.
16. A membrane as in claim 1 , wherein the spacing features are no more than 0.01″ in height.
17. A membrane as in claim 1 , wherein the spacing features are made of one or more of thermoplastics, reactive polymers, waxes, or resins; deposited directly onto the membrane surface.
18. A membrane as in claim 1 , wherein the spacing features are made of one or more of high-temperature thermoplastics, metals, or ceramics; formed apart from the membrane surface and then adhered to the membrane surface.
19. A permeable membrane system comprising a membrane as in claim 1 .
20. A method of treating water, comprising providing a permeable membrane system as in claim 19 , and passing water to be treated through the permeable membrane system.