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BR-112021000922-B1 - FILTER SCREEN AND METHOD FOR PURIFYING FEED WATER

BR112021000922B1BR 112021000922 B1BR112021000922 B1BR 112021000922B1BR-112021000922-B1

Abstract

FILTER SCREEN AND METHOD FOR PURIFYING FEED WATER. This refers to a filter screen having a plurality of slits, each slit having a longer main geometric axis A1 of length L, and each slit having a second geometric axis A2 perpendicular to A1 of length W, wherein the distance between adjacent slits in the direction of geometric axes A2 is XP; wherein XP is greater than W; wherein the distance between adjacent slits in the direction of geometric axes A1 is YP; wherein L is 800 micrometers or less and XP is 350 micrometers or less, or wherein L is 1600 micrometers or less and XP is 180 micrometers or less. A method for filtering feed water using such a filter screen is also provided.

Inventors

  • Abhishek Shrivastava
  • SCOTT T. BURR
  • Piyush Soni
  • LAURA J. DIETSCHE
  • SANTHOSH K. RAMALINGAM

Assignees

  • DDP SPECIALTY ELECTRONIC MATERIALS US, LLC

Dates

Publication Date
20260317
Application Date
20190710
Priority Date
20180727

Claims (13)

  1. 1. Filter screen (1) having a plurality of slits (2), wherein each slit (2) has a longer principal geometric axis A1 having a length L and each slit (2) has a second geometric axis A2 that is perpendicular to A1 and has a length W, wherein the slits (2) are arranged so that all geometric axes A1 are parallel to each other; the slits (2) are arranged in a plurality of rows, wherein the distance between the central points of adjacent slits in the direction of the geometric axes A2 is XP; wherein XP is greater than W; the slits (2) are arranged in a plurality of columns, wherein the distance between the nearest circumference points of adjacent slits in the direction of the geometric axes A1 is YP; wherein L is 1600 micrometers or less; wherein XP is 350 micrometers or less, characterized by the fact that W is from 10 μm to 50 μm, and wherein the filter has a curved surface.
  2. 2. Filter screen (1) according to claim 1, characterized in that L is 650 μm or less.
  3. 3. Filter screen (1) according to claim 1, characterized in that XP is 200 μm or less.
  4. 4. Filter screen (1) according to claim 1, characterized in that L is 800 μm or less and XP is 350 micrometers or less.
  5. 5. Filter screen (1) according to claim 1, characterized in that L is 1600 micrometers or less and XP is 180 μm or less.
  6. 6. Method for purifying feed water wherein the feed water comprises solid particles (5) from 5 μm to 100 μm in diameter, characterized in that the method comprises passing the feed water through the surface of the filter screen (1) as defined in claim 1, wherein the feed water passes over the surface of the filter screen (1) at a velocity Vt, wherein some part of the feed water passes through the slits (2) at a velocity Vr, and wherein the quotient Vt/Vr is from 1 to 100.
  7. 7. Method according to claim 4, characterized in that the quotient Vt/Vr is from 5 to 50.
  8. 8. Method according to claim 4, characterized in that the feed water comprises particles (5) of 10 μm to 25 μm in diameter.
  9. 9. Filter screen (1) according to claim 1, characterized in that L is 1,200 μm or less.
  10. 10. Filter screen (1) according to claim 1, characterized in that XP is 150 μm or less.
  11. 11. Filter screen (1) according to claim 1, characterized in that the curved surface is bounded by the upper and lower surfaces.
  12. 12. Filter screen (1) according to claim 1, characterized in that the slit (2) has a shape along the Z-axis that is substantially uniform.
  13. 13. Filter screen (1) according to claim 1, characterized in that 90% or more of the slits (2) have W, which has a W/Wav ratio of 0.8 to 1.2, wherein Wav is the average width of the slits (2) in that screen.

Description

[001] It is often desirable to purify water that contains undesirable particles. A useful method for removing undesirable particles is cross-flow filtration, in which water passes through the surface of a filter medium. A portion of the water passes through the filter medium and is eventually collected as the permeate, which is accumulated as purified water. Large particles fail to pass through the filter medium and remain in the water that passes over the surface of the filter medium. The water that does not pass through the filter medium continues through the surface of the filter medium, carrying the remaining large undesirable particles and is eventually collected as the retentate. [002] In some types of cross-flow filtration, the filter medium is a membrane that has a regular arrangement of parallel slits. Water flows across the surface of the membrane in a direction perpendicular to the long dimension of the slits. Water and particles that are much smaller than the smallest dimension of the slit pass through the slit. Particles that are much larger than the smallest dimension of the slit are rejected; that is, they remain in the retentate. Under some circumstances, since water and particles flow through the slits, some particles that are slightly smaller than the slits are also rejected; that is, they fail to enter the slits and are retained in the retentate. [003] It is desirable that as many particles as possible remain unretentate, so that the permeate is as pure as possible. In the past, increasing the rejection of small particles by increasing the speed at which water flows over the membrane surface has been considered. This approach requires undesirably high energy consumption and creates undesirable wear on the membrane. Alternatively, manufacturing membranes with smaller slits has been considered in the past. Such membranes are difficult to manufacture and reduce filter productivity. [004] It is desirable to provide a membrane with a size and slot arrangement that improves the filtration process. It is desirable to provide a size and slot arrangement that improves the membrane's ability to reject particles with the smallest possible diameter, preferably without the need for high-speed water flow over the membrane surface and/or without the need to reduce the width of the slots. It is desirable to provide filtration conditions that improve the membrane's ability to reject particles of the smallest possible diameter. [005] A statement of invention follows. [006] A first aspect of the present invention is a filter screen having a plurality of slits, each slit having a longer principal geometric axis A1 having a length L and each slit having a second geometric axis A2 that is perpendicular to A1 and having a length W, wherein the slits are arranged so that all geometric axes A1 are parallel to each other; the slits are arranged in a plurality of rows, wherein, within each row, the geometric axes A2 are collinear; wherein the distance between the central points of adjacent slits in the direction of the geometric axes A2 is XP; wherein XP is greater than W; the slits are arranged in a plurality of columns, wherein, within each column, the geometric axes A1 are collinear; wherein the distance between the nearest points on the circumference of adjacent slits in the direction of the geometric axes A1 is YP; wherein L is 800 micrometers or less; where XP is 350 micrometers or less. [007] A second aspect of the present invention is a method for purifying feed water, wherein the feed water comprises solid particles from 5 μm to 100 μm in diameter, wherein the method comprises passing the feed water through the surface of the filter screen of the first aspect, wherein the feed water passes over the surface of the filter screen at a velocity Vt, wherein some part of the feed water passes through the slits at a velocity Vr, and wherein the quotient Vt/Vr is from 1 to 100. [008] A third aspect of the present invention is a filter screen having a plurality of slits, each slit having a longer principal geometric axis A1 having a length L and each slit having a second geometric axis A2 that is perpendicular to A1 and has a length W, wherein the slits are arranged so that all geometric axes A1 are parallel to each other; the slits are arranged in a plurality of rows, wherein, within each row, the geometric axes A2 are collinear; wherein the distance between the central points of adjacent slits in the direction of the geometric axes A2 is XP; wherein XP is greater than W; the slits are arranged in a plurality of columns, wherein, within each column, the geometric axes A1 are collinear; wherein the distance between the nearest points on the circumference of adjacent slits in the direction of the geometric axes A1 is YP; wherein L is 1,600 micrometers or less; where XP is 180 micrometers or less. [009] A fourth aspect of the present invention is a method for purifying feed water, wherein the feed water comprises sol