1. Technical Field
The present invention relates to the field of desalination, and more particularly, to a vertical desalination element.
2. Discussion of Related Art
Current desalination plants at industrial scales use horizontal pressure vessels fitted with relatively small membrane elements. Scaling up desalination plants demands using larger membrane elements.
WIPO publication No. 2009087642, which is incorporated herein by reference in its entirety, discloses a desalination system with vertical elements.
Embodiments of the present invention provide a desalination element comprising: a vertical pressure vessel (PV) having a vertical axis, an upper end and a lower end; a plurality of membrane elements operable within the vertical PV; and a loading mechanism arranged to allow loading the membrane elements into the vertical PV, wherein the vertical arrangement of the membrane elements and the vertical PV is usable to enhance air bubble percolation, to increase construction efficiency and to allow handling heavy membrane elements.
These, additional, and/or other aspects and/or advantages of the present invention are: set forth in the detailed description which follows; possibly inferable from the detailed description; and/or learnable by practice of the present invention.
The present invention will be more readily understood from the detailed description of embodiments thereof made in conjunction with the accompanying drawings of which:
Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is applicable to other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
For a better understanding of the invention, the usages of the following terms in the present disclosure are defined in a non-limiting manner:
The term “pressure vessel (PV)” as used herein in this application, is defined as a closed container designed to hold liquids at a high pressure.
The term “membrane element” as used herein in this application, is defined as a mechanically supported semi-permeable membrane(s) constructed to function within a pressure vessel.
As desalination systems utilize larger and larger membrane elements, handling of single membrane elements becomes ever more cumbersome. Additionally, the membrane elements become ever more valuable and thus necessitate individual handling. Orienting the PVs vertically is a promising way to approach these challenges, and the current invention solves the problem of loading the membrane elements into the vertical PVs.
Desalination element 100 may comprise vertical PV 110 having a vertical axis 115, an upper end 119 and a lower end 111. Desalination element 100 further comprises loading mechanism 200 arranged to allow loading membrane elements 90 (operable within vertical PV 110) into vertical PV 110. The vertical arrangement of membrane elements 90 and vertical PV 100 allows using heavy membrane elements 90 and enhances their operability.
Loading mechanism 200 may be arranged to allow loading membrane elements 90 into vertical PV 110 by defining a first end of vertical PV 110 as an insertion opening and a first membrane element 90A to be inserted; inserting membrane elements 90 into the insertion opening, beginning with first membrane element 90A such as to define a last membrane element 90Z; and covering upper end 119 with an upper cover (not shown) and lower end 111 with a lower cover 230, the covers comprising sealing means and pipe interfaces, to yield an operable desalination element 100. Lower cover 230 may comprise openings for adapter and connectors enabling the functionality of PV 110. These openings are not always illustrated, for simplicity.
Loading mechanism 200 may be arranged to load membrane elements 90 into vertical PV 110 singly and sequentially, or groupwise and interconnected. Single loading has the advantages of handling one membrane element 90 at a time (the order of handling is denoted in the following description by 90A being the first membrane element, 90B the second membrane element and 90Z the last membrane element to be loaded), yet has the disadvantage of a sequentially recurring procedure taken for each PV 110. Groupwise loading has the advantage of a single action loading, yet requires a preparation process of connecting membrane elements 90.
Membrane elements 90 may be loaded onto a covered lower end 111, i.e., with lower cover 230 in place or usable during loading, or membrane elements 90 may be loaded onto a temporary support 190, that may support membrane elements 90 during their loading, and then allow inserting lower cover 230 therethrough and removing temporary support 190 from lower end 111 of PV 110.
Some of these possibilities are illustrated in
In the following diagrams, three loading methods are illustrated for loading membrane elements 90 singly and sequentially (101): using a holder 150 (102,
Loading methods 102, 104 utilize lower end 111 as the insertion opening, while loading methods 103, and the groupwise loading 107, 108, 109, 113 utilize upper end 119 as the insertion opening.
Loading mechanism 200 may comprise holder 150 positioned coaxially above vertical PV 110 and arranged to: extend through vertical PV 110 along its axis 115 (
Holder 150 may be arranged to connect to membrane element 90 by inflating inflatable member 155 within inner conduit 91 in membrane element 90, and detach membrane element 90 by deflating inflatable member 155. Connecting to additional element 90 may be carried out after detaching from connected membrane elements 90, i.e. sequentially.
Holder 150 with inflatable member 155 may be used in the following manner to load membrane elements 90 into vertical PV 110: first membrane element 90A may be positioned below vertical PV 110 (
Inflatable member 155 may then be inflated to affix second membrane element 90B, and holder 150 may heave first and second membrane element 90A, 90B by inflatable member 155 (
Inflatable member 155 may comprise a rubber balloon with attached inflating and deflating means, and may be structured and formed such as to optimally hold membrane element 90 by its inner conduit 91 without damaging or deforming membrane element 90. Inflatable member 155 may be further designed to enable supporting several membrane elements 90 upon lower membrane element 90A that is held by inflatable member 155.
Loading mechanism 200 may comprise telescopic piston 120 positioned coaxially below vertical PV 110 (FIGS. 3A-3F—support with lower cover 230 as lower fastener 245, FIGS. 3G-3L—support with a temporary cover 231, and covering lower end 111 with lower cover 230 as in
Temporary support 190 may be connected to lower end 111 and arranged to support membrane elements 90 (
Telescopic piston 120 may be connected to first membrane element 90A by lower cover 230, such that securing first membrane element 90A comprises the covering of lower end 111. Lower cover 230 may be configured to move through PV 110, and to allow connection to and departure from telescopic piston 120.
Loading mechanism 200 may further comprise temporary support 190 (
Loading mechanism 200 may be arranged to load membrane elements 90 into vertical PV 110 singly and sequentially through lower end (
Temporary support 190 may comprise retractable holders 192, with a retraction mechanism as illustrated in
Multiple retractable holders 192 may be held within a frame comprising an upper basis 193, a lower basis 206 with supporting elements 203 attached thereupon. The movement of retractable holders 192 may be achieved by an upper plate 204 and a lower plate 205 having guiding slits in which positioning pins 194 may move. Guiding slits 207 in lower plate 205 are radial and permit a radial movement of positioning pins 194 (and of retractable holders 192). Guiding slits 201 in upper plate 204 are diagonal and permit a diagonal movement, i.e. having a radial and a tangential component, of positioning pins 194 (and of retractable holders 192). Upper plate 204 is moveable, and is arranged to allow external control of the positions of retractable holders 192. In this way, turning upper plate 204 allows inserting membrane elements and supporting loaded membrane elements (e.g. as illustrated in
A permanent lower cover 230 as lower fastener 245 may be inserted through temporary support 190 in a similar manner to the loading of membrane elements 90, and be fixated into indentations or grooves in lower end 111. Temporary support 190 may be permanently connected or part of lower end 111 of vertical PV 110. Alternatively, after connecting permanent cover 195, retractable holder 190 may be removed and used on other vertical PVs 110.
Loading mechanism 200 may comprise a horizontal frame 210 (
Loading mechanism 200 may further comprise a crane 250 arranged to heave interconnected membrane elements 90 by upper connector 240 (
Interconnected membrane elements 90 may be fastened to horizontal frame 210 during or after their connecting. Interconnected membrane elements 90 may unfastened from horizontal frame 210 and then be lifted by crane 250 from horizontal frame 210, or crane 250 may lift horizontal frame 210 with interconnected membrane elements 90 to a vertical position and then interconnected membrane elements 90 may be unfastened from horizontal frame 210. Alternatively, horizontal frame 210 with interconnected membrane elements 90 may be brought to a vertical position by means other than crane 250, then crane 250 may be connected to upper connector 240, interconnected membrane elements 90 released from frame 210 and inserted into vertical PV 110.
Lower cover 230 may comprise two parts: a first part 236 designed to close PV 110 and to support membrane elements 90, and a second part 235 connectable to first part 236 and designed as an adapter for connecting pipes to PV 110 (
Second part 235 may be arranged to temporarily connect to releasable fastener 237. Second part 235 together with releasable fastener 237 may be connected to shaft 220 as lower fastener 245 (
Second part 235 and releasable fastener 237 may be configured to allow releasing releasable fastener 237 from second part 235, and releasable fastener 237 may be designed to allow its removal through conduit 91 with shaft 220 from PV 110. While operating together as lower fastener 245, second part 235 and releasable fastener 237 may support membrane elements 90, wherein the actual load of the membrane elements is sustained by second part 235, and releasable fastener 237 connects second part 235 to shaft 220.
Second part 235 and releasable fastener 237 may be shaped to allow disconnection upon rotation 239 of shaft 220. For example, releasable fastener 237 may engage second part 235 with protrusions 218 of releasable fastener 237 fitting into notches 217 in second part 235. Protrusions 218 and notches 217 may cover only a part of the perimeter of second part 235 and of releasable fastener 237, such as to allow release of releasable fastener 237 by rotational movement 239 applied to shaft 220 to which it is connected. Second part 235 stays in place and operates as an adaptor, while releasable fastener 237 is removed with shaft 220.
Lower fastener 245 may comprise inflatable member 155 connected to holder 150 and arranged to connect to or affix interconnected membrane elements 90 by inflation within inner conduit 91 in at least one of interconnected membrane elements 90 (
Inflatable member 155 may be connected to holder 150 and/or to shaft 220 and used to position interconnected membrane elements 90 onto the permanent lower cover 230 (
Lower fastener 245 may be the permanent lower cover 230 of lower end 111, or temporarily hold the lower membrane element 90 until the grouped membrane elements 90 are set into vertical PV 110. In the temporary version, membrane elements 90 may be inserted into vertical PV 110 with a covered lower end 111, and lower cover 230 may be configured to release the lower membrane element 90, e.g. by turning or by mechanical or electric activation from the upper end of shaft 220, to allow withdrawal of shaft 220 without lower cover 230 after setting membrane elements 90 thereupon.
Lower fastener 245 may comprise an extended nut 234 configured to go through an opening 247 in lower cover 230, or in a modified lower cover 233 (
Interconnected membrane elements 90 may be lifted by crane 250 (
Lower cover 230 may be a modified lower cover 233 having an opening 247 larger than the opening in lower cover 230, and an adapter 244 that may be connected to opening 247 to provide an interface with external product water pipes (
Temporary support 190 may be arranged to be removably connected to lower end 111, support loaded membrane elements 90, and allow connecting lower cover 230 to lower end 111, to replace temporary support 190.
Lower fastener 245 may be a nut 243, and interconnected membrane elements 90 may be inserted into vertical PV 110 by crane 250 (
Temporary support 190 may comprise retractable holders 192, with a retraction mechanism as illustrated in
Multiple retractable holders 192 may be held within a frame comprising an upper basis 193, a lower basis 206 with supporting elements 203 attached thereupon. The movement of retractable holders 192 may be achieved by an upper plate 204 and a lower plate 205 having guiding slits in which positioning pins 194 may move. Guiding slits 207 in lower plate 205 are radial and permit a radial movement of positioning pins 194 (and of retractable holders 192). Guiding slits 201 in upper plate 204 are diagonal and permit a diagonal movement, i.e. having a radial and a tangential component, of positioning pins 194 (and of retractable holders 192). Upper plate 204 is moveable, and is arranged to allow external control of the positions of retractable holders 192. In this way, turning upper plate 204 allows inserting membrane elements and supporting loaded membrane elements (e.g. as illustrated in
A permanent lower cover 230 may be inserted through temporary support 190 in a similar manner to the loading of membrane elements 90, and be fixated into indentations or grooves in lower end 111. Temporary support 190 may be permanently connected or part of lower end 111 of vertical PV 110. Alternatively, after connecting permanent cover 195, retractable holder 190 may be removed and used on other vertical PVs 110.
The first end may be an upper end of the vertical PV, and the second end may be a lower end of the vertical PV. The membrane elements may be inserted into the insertion opening (stage 320) singly and sequentially. The membrane elements may be supported (stage 321) on their downwards insertion by a device extending through the lower end and through the vertical PV or by a device extending through the upper end and through the vertical PV.
Method 300 may further comprise interconnecting at least some of the membrane elements before their insertion (stage 315), such that the membrane elements are inserted (stage 320) groupwise.
The first end may be a lower end of the vertical PV, and the second end may be an upper end of the vertical PV. The membrane elements may be inserted into the insertion opening (stage 320) singly and sequentially.
The membrane elements may be pushed upwards by a device extending through the lower end and through the vertical PV (stage 323).
The membrane elements may be pulled upwards by a device extending through the upper end and through the vertical PV (stage 324).
The membrane elements may be pushed upwards and temporarily supported at the lower end (stage 325).
Supporting the membrane elements (stage 321) may be carried out by connecting an accessorial appliance to the first membrane element either externally or internally at a cavity in the first membrane element.
Advantageously, the columnar arrangement of membrane elements 90 in vertical PVs 110 generates loads on membrane elements 90 which result in: (i) a limitation of the movement of membrane elements 90 upon changes in a flow of the feed water, as during initiation and stopping of the desalination process, (ii) a tolerance to thermal expansion and contraction of membrane elements 90, (iii) both (i) and (ii) allow disposing of the need to apply and replace spacers between membrane elements 90 (shimming) and avoid damage to sealing elements associated with membrane elements 90; and (iv) an efficient and full evacuation of foam produced during cleaning membrane elements 90, which may otherwise damage membrane elements 90 or require long time to evacuate.
The loading methods 300 and mechanisms 200 presented here allow to use heavy membrane elements 90 to benefit from these advantages, and further enhance their operability by generating the ability to replace individual membrane elements 90 that are find defective. It is only with the disclosed loading mechanisms 200 that handling large membrane elements 90 in an industrially acceptable scale becomes feasible.
In the above description, an embodiment is an example or implementation of the invention. The various appearances of “one embodiment”, “an embodiment” or “some embodiments” do not necessarily all refer to the same embodiments.
Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment.
Furthermore, it is to be understood that the invention can be carried out or practiced in various ways and that the invention can be implemented in embodiments other than the ones outlined in the description above.
The invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described.
Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined.
While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments. Other possible variations, modifications, and applications are also within the scope of the invention. Accordingly, the scope of the invention should not be limited by what has thus far been described, but by the appended claims and their legal equivalents.
This application claims the benefit of U.S. Provisional Patent Application 61/225,948 filed on Jul. 16, 2009, which is incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB10/53228 | 7/15/2010 | WO | 00 | 1/16/2012 |
Number | Date | Country | |
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61225948 | Jul 2009 | US |