AU2010202837B2 - An apparatus for treatment of water - Google Patents

Abstract

S u m m a r y An apparatus (1) for treatment of water where the apparatus (1) includes a pressure exchanger (12), and where the pressure exchanger (12) comprises a pressure vessel (16) having a movable fluid barrier (18) inside, and where the fluid barrier (18) is col s lapsible. (Fig. 2) -30 32 36 28 18 16Q 20 22 38 ___ .--- 14 -26 12 32 36 28 16b 18 20 22 Figl 1

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): Lyng Composite AS Invention Title: AN APPARATUS FOR TREATMENT OF WATER The following statement is a full description of this invention, including the best method for performing it known to me/us: P84544.AU 1A AN APPARATUS FOR TREATMENT OF WATER There is provided an apparatus for treatment of water. More precisely, there is pro vided an apparatus for treatment of water where the apparatus includes a pressure s exchanger, and where the pressure exchanger comprises a pressure vessel having a movable fluid barrier inside. There is also provided a method of erecting the fluid bar rier in the pressure vessel. The treatment of water refers to processes where energy recuperation by use of pres sure exchangers are possible, typically so called reverse osmosis and pressure re 10 tarded osmosis. Reverse osmosis (RO) is a filtration method that removes many types of large mole cules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. Pressure retarded osmosis (PRO), is commonly used for a salinity gradient energy re 1s trieved from the difference in the salt concentration between for instance seawater and river water. Below, the invention is explained under reference to a reverse osmosis process for water desalination. Reverse osmosis is becoming widely used, particularly for desalination of water, but 20 also other purification of water and other substances. As a desalination process commonly requires a pressure fall over the membrane of 60 bar, the process is relatively energy intensive. Waste water from the desalination process, that is water with increased salinity, may still have a pressure of just some bar less than the supply pressure. It is normal to 2 have 40% efficiency on the process, and approximately 60% of the supplied water is leaving as waste water. A potential energy recovery in the region of 50% is thus achievable, and most reverse osmosis plats include a pressure exchanger that recoup energy inside the process. 5 In fig. 1 an apparatus for treatment of water, more precisely a reverse osmosis plant, is schematically shown. The principle for the pressure exchanger is that waste water of a relatively high pressure is flowing into a pressure vessel and forcing a fluid barrier along the pressure vessel in order to expel water to be treated from the pressure ves sel at a lower pressure. A booster pump is feeding this water into an osmosis cham 10 ber. As the necessary increase in pressure is relatively modest, the energy consump tion is much lower than is required for a feed pump that have to bring the pressure of the supply water up from ambient pressure to full treatment pressure. The apparatus in fig. 1 is explained in more detail in the detailed part of the description. The pressure vessels have to work with water having relatively high salinity and corro 1s sion is a problem. Even normal grades of stainless and acid resistant steel suffer from problems like crevice corrosion. Pressure vessels must thus be produced in relative expensive materials in order to last. Common pressure vessels are often produced as flanged pipes having a blind flange type of end cover. 20 It is considered feasible to use a preferably liner equipped composite pipes as pressure vessels. Such vessel have excellent corrosion resistance and are relative inexpensive. So far stress concentration problems at the flanged ends have lead to increased pro duction cost and unacceptable operational difficulties. The purpose of the invention is to overcome or reduce at lest one of the disadvantages 25 of the prior art. The purpose is achieved according to the invention by the features as disclosed in the description below and in the following patent claims. There is provided an apparatus for treatment of water where the apparatus includes a pressure exchanger, and where the pressure exchanger comprises a pressure vessel 30 having a movable fluid barrier inside, wherein the fluid barrier is collapsible. A collapsible fluid barrier renders it possible to utilise a lined composite pressure ves sel having bulbous end parties. It is well known that a bulbous end party on a pres- 3 sure vessel reduces stress concentration substantially compared to a flanged end party. The downside is that an entrance opening of a metal coupling at the bulbous end party is much smaller than the cross section of the pressure vessel. By using a collapsible fluid barrier, the fluid barrier may be moved into the pressure 5 vessel through the entrance opening in its collapsed or unassembled state. A pressure vessel for use in connection with the present invention may have a fluid tight inner liner with a wear resistant, relatively smooth finish. The liner may thus constitute the inner mantel of the pressure vessel. The fluid barrier may comprise an elastic part that is designed to reduce a gap to 10 wards the inside mantel of the pressure vessel. The elastic part may be radially positioned in the pressure vessel by a guide. The pur pose of the guide is to keep the elastic part centred and in correct working position in the pressure vessel as the fluid barrier is moved along in the pressure vessel. The guide may include at least one member that is movable in the radial direction of is the inner mantel. The member may for instance be movable between a retracted, pas sive position during insertion into the pressure vessel, and an expanded, active posi tion. The fluid barrier may include more than one part that is erectable inside the pressure vessel. The elastic part may be inflatable. 20 The elastic part includes at least one readable object. The position of the fluid barrier inside the pressure vessel may thus be determined. The readable object may be a magnet, a metal part or an electronic item such as an RFID device. A method for installing a collapsible fluid barrier in a pressure vessel having an en trance opening where the entrance opening is smaller than the inside cross section of 25 the pressure vessel may include: - providing a collapsible fluid barrier that complementary fit in a pressure vessel; - collapsing the fluid barrier; - insert the fluid barrier through the entrance opening into the pressure vessel; and - restoring the fluid barrier to its working state. 30 The method may include dismantling and reassembly of parts of the fluid barrier, or deflation and inflation of an elastic part.

4 The apparatus and method of the invention makes it possible to utilize bulbous com posite pipes as pressure vessels in water treatment plants. It is reasonable to expect a substantial reduction in cost and maintenance when composite vessels replace metal vessels. s Below, an example of a preferred embodiment of the apparatus and method is ex plained under reference to the enclosed drawings, where: Fig. 1 shows an apparatus for treatment of water; Fig. 2 shows in a larger scale a vertical section of a pressure vessel wherein a fluid barrier according to the present invention is positioned; 10 Fig. 3 shows in a larger scale a perspectivic view of the fluid barrier in fig. 2; Fig. 4 shows a vertical cross section of the fluid barrier in fig. 3; Fig. 5 shows a part of the fluid barrier in fig. 4 in collapsed form; Fig. 6 shows an elastic part of the fluid barrier in fig. 4 in its collapsed form; Fig. 7 shows some parts of the fluid barrier in fig. 4 during assembly; is Fig. 8 shows an elastic part of an alternative embodiment in its deflated form; Fig. 9 shows the elastic part of fig. 8 in its inflated form; Fig. 10 shows an end view of a fluid barrier in another alternative embodiment; and Fig. 11 shows a section X-X in fig. 10. On the drawings the reference number 1 denotes a water treatment plant working on 20 the principle of reversed osmosis for desalination of water. Water to be treated is feed into an osmosis chamber 2 under relatively high pressure by a feed pump 4 from a supply pipe 6. The osmosis chamber 2 is equipped with a membrane 8 that is designed to let pure water pass. The purified water is leaving the osmosis chamber 2 via a purified water pipe 10 at a relatively low pressure. Waste 25 water having a higher salinity than the supply water, is feed into a pressure exchanger 12 feed pipe 14. The pressure exchanger 12 is equipped with two pressure vessels 16, referred to as 16a and 16b in fig. 1, having a movable fluid barrier 18 inside. The purpose of the 5 fluid barrier 18 is to avoid mixing of fluids in the pressure vessel 16a, 16b. The reason for having two or more pressure vessels 16a 16b is that one pressure vessel 16a will be receiving waste water while the other pressure vessel 16b is discharging waste wa ter. The operation of the two pressure vessels 16a 16b is identical and items having s the same function are referred to by the same reference numeral. The feed pipe 14 is connected to a first end party 20 of the pressure vessel 16a via a feed valve 22. The first end party 20 is connected to a discharge pipe 24 via a dis charge valve 26. The supply pipe 6 is connected to a second end party 28 of the pressure vessel 16a io via a supply pipe branch 30 and a supply valve 32. The second end party 28 is con nected to a booster pump 34 via an outflow valve 36 and a booster pipe 38. The booster pump 34 is supplying the osmosis chamber 2. The operation of the water treatment plant above is well known to a person skilled in the art. It is sufficient to say that while the feed valve 22 and the outflow valve 36 are is open at one pressure vessel 16a allowing waste water to move the fluid barrier 18 along the pressure vessel 16a and thus supplying the booster pump 34 with water, the discharge valve 22 and the supply valve 32 are open at the other pressure vessel 16b, allowing supply water to move the fluid barrier 18 along the pressure vessel 16b and thus expelling waste water through the discharge pipe 24. 20 Referring to fig. 2, the pressure vessel 16 have a load carrying cylinder 40 with a bul bous first and second end party 20, 28 made of composite on a liner 42. The first and second end parties 20, 28 have each a metal coupling 44 that have an entrance open ing 45. The load carrying cylinder 40 and the first and second end parties 20, 28 may be made of composite material such as glass, carbon and aramide fibre in a matrix of 25 polyester or epoxy. The liner 42 may be produced from a suitable polymer such as cross-linked polypropylene or polyamide. Inside the pressure vessel 16 a movable fluid barrier 18 is positioned. In this preferred embodiment the fluid barrier 18 comprises a disk shaped flexible member 46 with a guide 48 that is designed to keep the flexible member 46 in its working position seal 30 ing against the liner 42. The guide 48 comprises a boss 50 on each side of the flexible member 46, see figs. 3 and 4. A number of elongated, movable members 52, here three in each boss 50, are positioned in separate slots 54. The slots 54 are equally spaced around a centre line 56 of the fluid barrier 18. Each movable member 52 is hinged about a pin 58 in the 6 boss 50. At its opposite end the movable member 52 is provided with a dual wheel 60 that is intended to roll against the liner 42 when in its working position. The wheel 60 has a shaft 62 that fits in a recess 64 in the movable member 52. A cylinder 66 fits in a central boring 68 in the boss 50. When in position in the boring 5 68 the cylinder abuts a flat 70 on the movable member 52 the position of the flat 70 relative to the pin 58 secure that the movable member 52 then is in its working posi tion. The cylinder 66 also fits in an central opening 72 of the flexible member 46. A central bolt 74 and a nut 76 are used for locking the two bosses 50 and the flexible member together. A number of readable objects 78 in the form of magnets are posi 10 tioned inside the flexible member 46 close to its outer periphery. These readable ob jects 78 may be read in order to determine the position of the fluid barrier in the pres sure vessel 16. The objects 46, 48, 50, 52 and 66 are parts that are erectable inside the pressure vessel 16. is When the fluid barrier 18 is to be inserted and positioned in the pressure vessel 16, a boss with the movable members 52 in its passive position, see fig. 5, is connected to a first tool 80 and inserted through the entrance opening 45 in the first end party 20. The cylinder 66 is connected to a second tool 82, inserted through the entrance open ing 45 in the second end party 28, and into the boring 68, see fig. 7. In doing so, the 20 movable members 52 are moved to its working position as described above. The second tool 82 is withdrawn, where after the flexible member 46 rolled to a roll, see fig. 6, and inserted through the entrance opening 45 of the second end party 28. The flexible member is inserted on the cylinder 66 through the opening 72. Thereafter the other boss 50 with collapsed movable members 52 is inserted by the 25 use of the second tool 82 and pushed on to the cylinder 66. The movable members 52 are then moved to their working position. After removing the tools 80 and 82, the bolt 74 are inserted and tightened. The fluid barrier 18 is then operational in the pressure vessel 16. In an alternative embodiment the fluid barrier 18 may have a flexible member 46 in 30 the form of an inflatable member 84. A valve 86 is used for inflating and deflating the member 84. A rubber like material may be used. When deflated, see fig. 8, the mem ber 84 may be inserted through one entrance opening 45 of the pressure vessel 16.

7 When inflated, the member 84 will resume its shape, here spherical, as shown in fig. 9. In yet an alternative embodiment the fluid barrier 18 includes a central disc 88 and four segments 90, see figs 10 and 11. Each of the disc 88 and the segments 90 are s small enough to pass through the entrance openings 45. After insertion into the pres sure vessel 16, each of the segments 90 are fixed to the disc 88 by screws 92 to form a piston like fluid barrier 18. The items 88, 90 are erectable inside the pressure vessel 16. It is to be understood that, if any prior art publication is referred to herein, such refer 10 ence does not constitute an admission that the publiction forms a part of the common general knowledge in the art, in Australia or any other country. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implica tion, the word "comprise" or variations such as "comprises" or "comprising" is used in is an inclusive sense, i.e. to specify the presence of the stated features but not to pre clude the presence or addition of further features in various embodiments of the in vention.

Claims (10)

1. An apparatus (1) for treatment of water where the apparatus (1) includes a pressure exchanger (12), and where the pressure exchanger (12) comprises a pressure vessel (16) having an axially movable fluid barrier (18) inside, 5 c h a r a c t e r i z e d b y that the axially fluid barrier (18) is collapsi ble.

2. An apparatus according to claim 1, c h a r a c t e r i z e d b y that the axially movable fluid barrier (18) comprises a flexible member (48) that is designed reduce a gap towards an inside mantel of the pressure vessels (16). 10

3. A device according to claim 2, c h a r a c t e r i z e d b y that the axially movable flexible member (48) is radially positioned in the pressure vessel (16) by a guide (48).

4. A device according to claim 3, c h a r a c t e r i z e d b y that the guide (48) includes at least one member (52) that is movable towards the inner 15 mantel of the pressure vessel (16).

5. A device according to claim 1, c h a r a c t e r i z e d b y that the axially movable fluid barrier (18) includes more than one part (46, 48, 50, 52, 66, 88, 90) that is erectable inside the pressure vessel (16).

6. A device according to claim 2, c h a r a c t e r i z e d b y that the 20 flexible member (46) is inflatable.

7. A device according to claim 2, c h a r a c t e r i z e d b y that the flexible member (48) includes at least one readable object (78).

8. A method for installing a collapsible, axially movable fluid barrier (18) according to claim 1 in a pressure vessel (16) having an entrance opening (45) where the 25 entrance opening (45) is smaller than the inside cross section of the pressure vessel (16), c h a r a c t e r i z e d b y that the method includes: - providing a collapsible fluid barrier (18) that complementary fits in a pressure vessel (16); - collapsing the axially movable fluid barrier (18); 30 - insert the axially movable fluid barrier (18) through the entrance opening (45) into the pressure vessel (16); and - restore the axially movable fluid barrier (18) to its working state. 9

9. A device according to claim 8, c h a r a c t e r i z e d b y that the method includes dismantling and reassembly of parts (46, 48, 50, 52, 66, 88, 90).

10. A device according to claim 8, c h a r a c t e r i z e d b y that the 5 method includes deflation and inflation of an flexible member (46).