US-12616939-B2 - Variable velocity patterns in cross-flow filtration

US12616939B2US 12616939 B2US12616939 B2US 12616939B2US-12616939-B2

Abstract

Embodiments of the present invention provide methods and apparatuses that can alter flow characteristics within the feed channel of a cross-flow filtration element by employing a varying geometry of the feed spacer at a fixed channel height.

Inventors

Rodney E Herrington
Kevin Roderick
Stephen Aulbach
Jay Kendall Weingardt
Jay Collin Weingardt
Nelson Longmire

Assignees

AQUA MEMBRANES, INC.

Dates

Publication Date: 20260505
Application Date: 20210702

Claims (5)

1 . A membrane sheet for use in a laminated composition, wherein the membrane sheet has an active surface configured to provide selective fluid separation, wherein the membrane sheet has feed spacing features disposed thereon, wherein a portion of the membrane occupied by the feed spacing features varies from a first end of the membrane sheet to an opposite end of the membrane sheet, from a first edge of the membrane sheet to a second edge of the membrane sheet, or both; wherein each feed spacing feature extends from near the first edge of the membrane sheet to near the second edge of the membrane sheet, and has a width that is greater near the first edge of the membrane sheet than near the second edge of the membrane sheet.
2 . The membrane sheet of claim 1 , wherein the feed spacing features are separated by a distance measured parallel to the first edge, where the distance is greater in a region near the first end of the membrane sheet than in a region near the second end of the membrane sheet.
3 . The membrane sheet of claim 1 , further comprising: (a) a permeate carrier; (b) wherein the membrane sheet is disposed such that the surface of the membrane sheet opposite the active surface is in contact with the permeate carrier, the membrane sheet and the permeate carrier together forming a laminated composition.
4 . A spiral wound element, comprising a collection tube and a laminated composition as in claim 3 , spirally wound around the collection tube such that the permeate carrier is in fluid communication with the collection tube.
5 . A method of treating water, comprising providing a spiral wound element as in claim 4 , supplying feed water to the spiral wound element such that feed water is in contact with the active surface of the membrane sheet, and collecting treated water from the collection tube.

Description

TECHNICAL FIELD The subject invention relates to a membrane system utilized for the separation of fluid components, specifically cross-flow and spiral-wound membrane elements. BACKGROUND ART In cross-flow filtration, a feed fluid flows through a filter and is released at the other end, while some portion of the fluid is removed by filtration through a membrane surface which is parallel to the direction of fluid flow. Various forms of cross-flow filtration exist including plate-and-frame, cassette, hollow-fiber, or spiral wound systems. Plate-and-frame, cassette, and spiral-wound filtration modules often rely on stacked membrane layers which provide spacing between adjacent layers of filtration membrane and the present invention is applicable to such systems. Spiral-wound membrane filtration elements are known in the art and comprise a laminated structure having of a membrane sheet sealed to or around a porous permeate carrier which creates a path for removal, longitudinally to the axis of the center tube, of the fluid passing through the membrane to a central tube, while this laminated structure is wrapped spirally around the central tube and spaced from itself with a porous feed spacer to allow axial flow of the fluid through the element. Traditionally, a feed spacer is used to allow flow of the feed water, some portion of which will pass through the membrane, into the spiral wound element and allow reject water to exit the element in a direction parallel to the center tube and axial to the element construction. Improvements to the design of spiral wound elements have been disclosed in U.S. Pat. No. 6,632,357 to Barger et al, U.S. Pat. No. 7,311,831 to Bradford et al, and patents in Australia (2014223490) and Japan (6499089) entitled “Improved Spiral Wound Element Construction” to Herrington et al which replaces the feed spacer with islands or protrusions either printed, deposited or embossed directly onto the inside or outside surface of the membrane. US patent application PCT/WO2018190937A1 entitled “Graded spacers for filtration wound elements” to Roderick, et al, describe the use of height graded spacer features which are used to alter feed flow characteristics in a spiral wound element. DESCRIPTION OF INVENTION Embodiments of the present invention provide methods and apparatuses that can alter flow characteristics within the feed channel of a cross-flow filtration element by employing a varying geometry of the feed spacer at a fixed channel height. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a spiral wound membrane element. FIG. 2 is an exploded view of a partially assembled spiral wound membrane element. FIG. 3 is a view of a spiral-wound element before rolling with a printed flow control spacer which increases uniformly in width from the feed inlet to the concentrate outlet, occluding about 20% of the cross-flow area at the outlet. FIG. 4 is a view of a spiral-wound element before rolling with a printed flow control spacer which increases uniformly in width from the feed inlet to the concentrate outlet, occluding approximately 50% of the cross-flow area at the outlet. FIG. 5 is a view of a spiral-wound element before rolling with a printed flow control spacer which increases in a stepwise manner in width from the feed inlet to the concentrate outlet, occluding approximately 20% of the cross-flow area at the outlet. FIG. 6 is a view of a spiral-wound element before rolling with a printed flow control spacer consisting of lines which increase in number from the feed inlet to the concentrate outlet. FIG. 7 is a view of a spiral-wound element before rolling with a printed flow control spacer which increases uniformly in width from the feed inlet to the concentrate outlet which also contains uniformly distributed feed spacer features. FIG. 8 is a view of a spiral-wound element before rolling with an array of printed flow control spacers comprising an array of round spacing features which increase in size from the feed inlet to the concentrate outlet. FIG. 9 is a view of a spiral-wound element before rolling with an array of printed flow control spacers comprising an array of round spacing features which increase in size from the feed inlet to the concentrate outlet, and also increase in size from the distal end to the center tube. MODES FOR CARRYING OUT THE INVENTION AND INDUSTRIAL APPLICABILITY The feed spacer in a spiral wound filtration element is required to maintain a channel for feed fluid to flow through, but the spacer design also impacts local flow velocities, turbulence, stagnation zones and other fluid flow conditions. Extruded mesh feed spacers have been used traditionally in membrane manufacture due to their ease of integration in the production process, but by the nature of their design many of their hydrodynamic characteristics are dependent on the thickness of the spacer. Printed feed spacers allow for unique design characteristics unobtainable with conventional extrud