Water filter

Abstract

A filter arrangement includes: a chamber including a chamber inlet for unfiltered liquid, a chamber outlet for filtered liquid and a wall arranged to keep the unfiltered liquid and the filtered liquid separated, a filter element having a longitudinal extension arranged inside of the chamber, wherein the filter element includes a semi-permeable filtration wall including a folded filter arranged in a zig-zag configuration between an inner perforated cylinder and an outer perforated cylinder and an internally located back-washing arrangement. The back-washing arrangement includes: an elongated and hollow body having a longitudinal extension, which is substantially parallel to the longitudinal extension of the filter element, a mechanism configured to drive the body in a rotational and/or an axial movement, a plurality of nozzles arranged in fluid communication with a cavity inside of the body, the plurality of nozzles projecting laterally from the body such that a distal end of each of the plurality of nozzles is arranged in close proximity to the inner perforated cylinder and an outlet arranged in fluid communication with the cavity of the elongated and hollow body and wherein the plurality of nozzles are arranged parallel to each other along a straight line on the body such that they all project in the same direction.

Claims

1. A filter arrangement comprising: a chamber comprising a chamber inlet for unfiltered liquid, a chamber outlet for filtered liquid and a wall arranged to keep the unfiltered liquid and the filtered liquid separated; a filter element having a longitudinal extension arranged inside of said chamber, wherein said filter element comprises a semi-permeable filtration wall comprising a folded filter arranged in a zig-zag configuration between an inner perforated cylinder and an outer perforated cylinder; and an internally located back-washing arrangement; wherein said back-washing arrangement comprises: an elongated and hollow body having a longitudinal extension, which is substantially parallel to the longitudinal extension of the filter element; a mechanism configured to drive said body in a rotational and/or an axial movement; a plurality of nozzles, wherein each one of said plurality of nozzles comprises a channel having a channel width, and wherein each one of said channels of said plurality of said nozzles is arranged in fluid communication with a cavity inside of said body, said plurality of nozzles projecting laterally from said body such that a distal end of each of said plurality of nozzles is arranged in close proximity to said inner perforated cylinder; and an outlet arranged in fluid communication with said cavity of said elongated and hollow body; wherein said plurality of nozzles are arranged parallel to each other along a straight line on said body such that they all project in the same direction, wherein the distance between two adjacent nozzles at or adjacent proximal ends of said plurality of nozzles is equal to or less than said channel width at or adjacent the proximal ends of said nozzles, wherein the filter arrangement comprises a cap which covers the distal end of at least one of said plurality of nozzles.

2. The filter arrangement according to claim 1, wherein the distal end of at least one of said plurality of nozzles is arranged in close proximity or in contact with the inner perforated cylinder by keeping said nozzles under spring load such that the distal end of said nozzle will follow the surface of said inner perforated cylinder while the back-washing arrangement is rotated.

3. The filter arrangement according to claim 1, wherein said plurality of nozzles comprises 2-20 nozzles, or 5-15 nozzles, or 5-10 nozzles.

4. The filter arrangement according to claim 1, wherein said cap is common for all of said plurality of nozzles, covering each one of said distal ends.

5. The filter arrangement according to claim 1, wherein said cap comprises at least one opening which is arranged over an opening of one of said plurality of nozzles such that a liquid is allowed to flow into said nozzle from the opposite side of said filtration wall.

6. The filter arrangement according to claim 1, wherein said back-washing arrangement further comprises a balancing piece or a plurality of balancing pieces arranged on said elongated body, said balancing piece or said plurality of balancing pieces projecting laterally from said elongated body such that a distal end of said balancing piece or of each one of said plurality of balancing pieces is arranged in close proximity to said inner perforated cylinder.

7. The filter arrangement according to claim 6, wherein said balancing piece is a dummy, or wherein said plurality of balancing pieces is a plurality of dummies.

8. The filter arrangement according to claim 6, wherein said plurality of nozzles is a first plurality of nozzles and wherein said plurality of balancing pieces is a second plurality of nozzles in fluid communication with said cavity inside of said body; wherein said second plurality of nozzles are arranged parallel to each other along a straight line on said body such that they all project in the same direction.

9. The filter arrangement according to claim 1, wherein perforations of said folded filter have a size which is smaller than the perforations of said inner and outer perforated cylinder.

10. The filter arrangement according to claim 1, wherein said filter element is a first filter element, wherein said filter arrangement comprises additional filter elements having the same or corresponding features as said first filter element.

11. A method for back-washing a filter arrangement according to claim 1, wherein said method comprises the steps of: creating a pressure difference between said chamber and the inside of each one of said plurality of nozzles such that a liquid is caused to flow in a reverse direction through the filter where each one of said plurality of nozzles are located; and moving said body rotationally and/or axially.

12. The method according to claim 11, wherein said step of creating a pressure difference is initiated when there is a pressure-drop over said filter of 0.2-1 bar, or 0.3-0.8 bar, or 0.4-0.6 bar.

13. A filter arrangement comprising: a chamber comprising a chamber inlet for unfiltered liquid, a chamber outlet for filtered liquid and a wall arranged to keep the unfiltered liquid and the filtered liquid separated; a filter element having a longitudinal extension arranged inside of said chamber, wherein said filter element comprises a semi-permeable filtration wall comprising a folded filter arranged in a zig-zag configuration between an inner perforated cylinder and an outer perforated cylinder; and an internally located back-washing arrangement; wherein said back-washing arrangement comprises: an elongated and hollow body having a longitudinal extension, which is substantially parallel to the longitudinal extension of the filter element; a mechanism configured to drive said body in a rotational and/or an axial movement; a plurality of nozzles, wherein each one of said plurality of nozzles comprises a channel having a channel minimum width, and wherein each one of said channels of said plurality of said nozzles is arranged in fluid communication with a cavity inside of said body, said plurality of nozzles projecting laterally from said body such that a distal end of each of said plurality of nozzles is arranged in close proximity to said inner perforated cylinder; and an outlet arranged in fluid communication with said cavity of said elongated and hollow body; wherein said plurality of nozzles are arranged parallel to each other along a straight line on said body such that they all project in the same direction, wherein the distance between two adjacent nozzles at or adjacent proximal ends of said plurality of nozzles is equal to or less than said channel minimum width, wherein the filter arrangement comprises a cap which covers the distal end of at least one of said plurality of nozzles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above objects, as well as additional objects, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of embodiments of the present invention, when taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1a shows a schematic view of filter arrangement in accordance with at least one example embodiment of the invention;

(3) FIG. 1b shows a schematic, perspective and cross-sectional view of the filter arrangement in accordance with at least one example embodiment of the invention;

(4) FIG. 2a shows a schematic view of a filter element in accordance with at least one example embodiment of the invention;

(5) FIG. 2b shows a schematic and cross-sectional view of a filter element in accordance with at least one example embodiment of the invention;

(6) FIGS. 3a-b shows schematic views of a back-washing arrangement in accordance with at least one example embodiment of the invention;

(7) FIG. 4a shows a schematic view of a cap in accordance with at least one example embodiment of the invention;

(8) FIG. 4b shows a schematic, cross-sectional view of a cap in accordance with at least one example embodiment of the invention;

(9) FIGS. 5a-c show cross-sectional views of a filter element in accordance with at least one example embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(10) In the present detailed description, embodiments of the present invention will be discussed with reference to the accompanying figures. It should be noted that this by no means limits the scope of the invention, which is also applicable in other circumstances for instance with other types or variants of filter arrangements encompassed by the scope of the claims than the embodiments shown in the appended drawings. Further, that specific features are mentioned in connection to an embodiment of the invention does not mean that those features cannot be used to an advantage together with other embodiments of the invention.

(11) FIGS. 1a and 1b shows a filter arrangement 1. The filter arrangement 1 in FIG. 1 is adapted for filtration of ballast water. The filter arrangement 1 comprises a chamber 12, a filter element 2 and a back-washing arrangement 3. The chamber 12 comprises a chamber inlet 14 for unfiltered water, a chamber outlet 16 for filtered water, a wall 18, an intake section 120 and a filter section 122. The filter element 2 comprises a semi-permeable filtration wall 22 comprising an inner perforated cylinder 26, an outer perforated cylinder 28 and a folded filter 24 (not visible in FIG. 1). Further, the filter element comprises end parts 220a, b. The back-washing arrangement 3 comprises an elongated and hollow body 32, a plurality of nozzles 34, a balancing piece 340 and a mechanism configured to drive said body 32 in a rotational and/or an axial movement. Here, the plurality of nozzles 34 comprises eight nozzles. The back-washing arrangement further comprises a cap 38 covering the distal ends 36 of each of said plurality of nozzles 34. The cap 38 in FIG. 1 is common for all of the plurality of nozzles 34 and comprises eight openings. In addition, the back-washing arrangement further comprises an outlet 320 arranged in fluid communication with said cavity of said elongated and hollow body.

(12) The inlet for water 14 is arranged in fluid communication with the intake section 120 and the outlet for filtered water is arranged in fluid communication with the filter section 122. The wall 18 is arranged between said intake section 120 and said filter section 122 to keep unfiltered water in the intake section 120 separated from filtered water, i.e. water which has passed through the filter wall 22, in the filter section 122. In other words, the wall 18 hinders dirty, unfiltered water to contaminate clean, filtered water.

(13) The filter element 2 is in the form of a cylinder which has a longitudinal extension. Moreover, the filter element 2 is arranged inside of the filter chamber 122. The folded filter 24 is arranged in a zig-zag configuration around the circumference of the filter element 2 and between the inner and the outer perforated cylinders 26,28.

(14) The back-washing arrangement 3 is arranged inside of the filter element 2. The body 32 has a longitudinal extension which is substantially parallel to the longitudinal extension of the filter element 2. The plurality of nozzles 34 is projecting laterally from the body 32 such that a distal end of each of said plurality of nozzles 34 are arranged in close proximity to said inner perforated cylinder 26. Moreover, the plurality of nozzles 34 are arranged parallel to each other along a straight line on said body 32 such that they all project in the same direction and such that each one of said plurality of nozzles 34 is arranged in contact with another one of said plurality of nozzles 34. Each one of the plurality of nozzles 34 is arranged in fluid communication with a cavity inside of said body 32.

(15) The plurality of nozzles is arranged in close proximity to the inner perforated cylinder 26 by a spring 342 such that each one of the plurality of nozzles 34 is under spring load and thereby pressed against the inner perforated cylinder 26. By keeping the nozzles under spring load they can stay in close proximity or in contact with the inner perforated cylinder 26 even though the surface of the cylinder is not completely flat.

(16) The openings 380 (see FIG. 4a, b) of the cap 38 is arranged over an opening of each one of said plurality of nozzles 34 such that a liquid is allowed to flow into said nozzle from the opposite side of said filter wall 22. The cap 38 is arranged to hinder unfiltered water from inside the filter element 2 to enter the nozzle while allowing for filtered, clean water to enter the plurality of nozzles 34 from the outside of said filter element 22.

(17) Two coordinate systems are presented in FIG. 1, an orthogonal coordinate system comprising x, y, z-axis and a cylindrical coordinate system comprising z, r, -axis. In both coordinate system is the longest extension or the central axis of the filter element 2 and the longest extension of elongated body 32 of the back-washing arrangement 3 parallel to the z-direction. The direction in which each one of the plurality of nozzles 34 projects laterally from the elongated body 32 of the back-washing arrangement 3 is parallel to the r-axis of the cylindrical coordinate system and the x-axis of the orthogonal coordinate system is. In addition, there is an angular -axis in the cylindrical coordinate system describing the position of the nozzles 34 during rotation. In the cylindrical coordinate system, the r- and -coordinates are the same for all of the plurality of nozzles 34 whereas each one of the plurality of nozzles 34 have an individual z-coordinate. In the orthogonal coordinate system, the x- and y-coordinates may be the same for all of the plurality of nozzles 34 whereas each one of the plurality of nozzles 34 have an individual z-coordinate.

(18) FIGS. 2a and 2b shows a filter element of a filter arrangement, such as said filter element 2 of said filter arrangement 1 shown in FIG. 1.

(19) FIG. 2a shows the inner and the outer perforated cylinders 26, 28 as well as the end parts 220a, b covering the gap between said inner and outer perforated cylinder 26, 28 at the ends of the filter wall 22. Hence, the folded filter between the inner and the outer perforated cylinders 26, 28 is not visible in FIG. 2. The perforations of said inner and outer perforated cylinders 26,28 are larger than the perforations of said folded filter.

(20) FIG. 2b shows a cross-section of the filter wall 22. Here, it is visible that the folded filter 24 is arranged in a zig-zag manner between the inner and the outer perforated cylinders 26, 28, along the circumferential direction.

(21) FIG. 3a shows the back-washing arrangement 3 of FIG. 1. In FIG. 3 it is seen that the back-washing arrangement further comprises a connector scanner 302, a drive pipe 306 comprising internal splines 304, a first entering guide 308 and a second entering guide 310. When mounted in the filter arrangement 1, and when in use, the internal splines 304 may be connected to external splines of a shaft of the motor (not visible in FIG. 3) which rotates said back-wash arrangement.

(22) FIG. 3b shows a back-washing arrangement 3 having the same functionality as the back-washing 3 arrangement described above in connection with FIGS. 1a, b and 3a. The back-washing arrangement 3 comprises two pluralities of nozzles 134a, b which are arranged on opposite sides of the elongated body 132. As the back-washing arrangement 3 of FIG. 3b is in large the same as the back-washing arrangement 3 of FIGS. 1 and 3a, focus on the description related to FIG. 3b will be on the differences compared to the support structure 1 of FIG. 1. In FIG. 3b, the same reference numerals as in FIGS. 1 and 3a, but with an extra 1 in front of the number, is used for corresponding features, where a is added to indicate the first plurality of nozzles and where b is added to indicate the second plurality of nozzles.

(23) The two pluralities of nozzles 134a, b is arranged offside to each other in the z-direction such that a center point of an opening of a nozzle in said second plurality of nozzles 134b is arranged between the respective center point of two nozzles in said first plurality of nozzles 134a. In FIG. 3b, a center point of an opening of a nozzle in the second plurality of nozzles 134b is arranged at a distance which is half the distance between two center point or respective openings of two nozzles in the first plurality of nozzles.

(24) FIG. 4 shows the cap 38 which may cover the distal end of at least one of the plurality of nozzles 34 seen in FIG. 1 and FIG. 3. FIG. 4a shows a top view of a cap which is designed for covering eight nozzles. Hence, the cap is designed for covering all of the plurality of nozzles 34 of the back-washing arrangement 3 of FIG. 1 and FIG. 3. FIG. 4b shows a cross-sectional view along the line a-a of the cap 38.

(25) The cap 38 comprises eight openings 380 which openings allow for water or any other liquid to enter the nozzles from the opposite side of the filter wall 22. Hence, during back-washing of the filter element 2 water will flow in a reverse direction through the filter wall 22 and subsequently through the opening 380 of the cap 38 and into the nozzle. The cap 38 further comprises cap walls 382a, b, which may hinder dirty water from inside of said filter element 2 to flow into the nozzles.

(26) FIG. 5a shows a cross-sectional view of a filter element. The filter element may for example be the filter element 2 shown in FIG. 1. Inside of the filter element 2 the back-washing arrangement 3 is arranged. The back-washing arrangement 3 comprises one plurality of nozzles 34. The balancing piece, i.e. the dummy, is not visible in this cross-sectional view. The filter element shown in FIG. 5a, may also be another filter element in which a back-washing arrangement 3 does not comprise any balancing piece.

(27) FIG. 5b shows a cross-sectional view of a filter element 2 having the same functionality as the filter element 2 as described above in connection to FIGS. 1 and 2. Arranged inside of the filter element 2 there is a back-washing arrangement 3 having the same functionality as the back-washing 3 arrangement described above in connection with FIGS. 1 and 3. The back-washing arrangement 3 comprises two pluralities of nozzles 134a,b which are arranged on opposite sides of the elongated body 132. The angle formed between the two pluralities of nozzles 134a, b is 180.

(28) FIG. 5c shows a cross-sectional view of a filter element 2 having the same functionality as the filter elements 2 and 2 as described above in connection to FIGS. 1 and 2. Arranged inside of the filter element 2 there is a back-washing arrangement 3 which may for example be the back-washing arrangement 3 in FIG. 3b. The back-washing arrangement 3 comprises three pluralities of nozzles 1034a, b, c. The angles formed between each of the pluralities of nozzles 1034a, b, c is 120.

(29) The skilled person realizes that a number of modifications of the embodiments described herein are possible without departing from the scope of the invention, which is defined in the appended claims. For instance, there may be further pluralities of nozzles arranged on the elongated body or the nozzles may be arranged in close proximity to the inner perforated cylinder by other means than springs.