AU2010212452A1

AU2010212452A1 - Desalination Unit

Info

Publication number: AU2010212452A1
Application number: AU2010212452A
Authority: AU
Inventors: Don Mcpherson; Brian Schulz
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-08-28
Filing date: 2010-08-19
Publication date: 2011-03-17

Description

DESALINATION UNIT TECHNICAL FIELD The present invention relates to a desalination unit particularly although not exclusively a self-contained reverse osmosis desalinisation unit for the 5 desalination of bore, sea and brackish water. BACKGROUND TO THE INVENTION The present invention relates to a desalination unit that can be used to desalinate bore, sea or brackish water. In addition to large scale desalination plants, smaller desalination units are often used in domestic 10 and small-scale industrial settings to provide clean water for a variety of purposes. These desalination units typically comprise a number of desalination membranes through which water flows thereby removing salt and other contaminants. In conventional desalination units, the membranes are 15 usually held horizontally and held in place by brackets. This can make the units unnecessarily bulky and also prone to damage during installation. SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a desalination unit comprising a plurality of desalination membranes provided 20 in a housing wherein the desalination membranes are coupled to each other and arranged to receive unclean water at an inlet and clean water at an outlet. Preferably, the desalination membranes are arranged in a substantially parallel orientation. Preferably, the desalination membranes are arranged 25 in a substantially vertical orientation. Preferably, the housing includes upper and lower retention means for supporting the desalination membranes in the substantially vertical orientation.

3 Preferably, each of the upper and lower retention means comprises a plate having a plurality of apertures provided therein, the upper and lower retention means being supported within the housing so as to be arranged substantially opposite and parallel to each other such to define respective 5 pairs of opposing apertures for retaining opposing ends of the desalination membranes therein. Preferably, adjacent desalination membranes are connected together by connection means for feeding water from one membrane to the next, the connection means being of arcuate construction. 10 Preferably, the desalination unit includes means arranged to receive a signal indicative of when the level of water in a remote storage tank below a minimum or above a maximum level and valve means operable in response to the signal to control the flow of water into the desalination means via the inlet. 15 Preferably, the desalination unit includes means for measuring waste water pressure and valve means operable to control the flow of waste water in response thereto. Preferably, the desalination unit includes means for providing a visual indication of the amount of waste water produced by the desalination unit. 20 Preferably, the desalination unit includes means monitoring the total dissolved solids in clean water produced by the desalination unit. In this specification, unless the context clearly indicates otherwise, the term "comprising" has the non-exclusive meaning of the word, in the sense of 25 "including at least" rather than the exclusive meaning in the sense of "consisting only of". The same applies with corresponding grammatical changes to other forms of the word such as "comprise", "comprises" and so on.

4 BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 5 Figure 1 is a front perspective of the housing of a desalination unit; Figure 2 is a rear perspective view of the housing of the desalination unit of Figure 1; Figure 3 is a block diagram of the components of a desalination unit of the invention; 10 Figure 4 is a front perspective view of a frame for mounting of components thereon within the housing of Figures 1 and 2; Figure 5 is a front perspective of the frame of Figure 4 with the desalination membranes mounted thereon; Figure 6 is a front perspective of the frame of Figure 4 with the pump and 15 instrumentation housings mounted thereon; and Figure 7 is a perspective view of the top of the frame of Figure 4 showing details of the connections between desalination membranes. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS A desalination unit 1 of the invention comprises a housing 2 having side 20 walls 3, 4, 5, 6 and a top panel 7. The housing 2 houses a frame 8 which supports the internal components and circuitry of the desalination unit 1 as will be described in further detail below. The front wall 3 includes apertures for mounting various instrument gauges - such as a display panel 9 for a computer 35, displays 10 of flow gauges 47, 50 and a display 11 for total 25 dissolved solids ("TDS") monitoring device 51 - flush with the front wall 3. Typically, the front wall 3 and the top panel 7 are made from 1mm thick powder coated zinc material. The other walls 4, 5, 6 are made of frosted 5 acrylic material, although it will be understood that other materials could be used. In the embodiment described herein, the housing 2 is approximately 730mm in width, 1525mm in height and a depth of 580mm. The frame 8 comprises four vertical posts 12 connected by sets of horizontal 5 cross posts or struts 13a, 13b, 13c to hold the vertical posts 12 in place. The frame 8 comprises four lower cross posts 13a towards the base of the vertical posts 12, four 13b at the top of the vertical posts 12 and four 13c provide midway between the base and the top, each set of four in a substantially horizontal rectangular arrangement. In this way the vertical 10 posts 12 are arranged to define a rectangular-shaped frame around which the housing 2 is fitted - and as illustrated schematically in Figure 4. Additional pairs of supporting cross posts 14a, 14b; 15a, 15b are provided in opposite vertical faces 16, 17 of the frame 8 to provide support for additional components as will be described in further detail below. The first 15 pair 14a, 14b of support posts is provided towards the upper portion of the frame 8 and the second pair 15a, 15b towards the bottom portion of the frame 8 as illustrated in Figure 3. Additional support posts 18 are provided at the base 19 of the frame 8. The additional support posts 18 are provided to support a pump 37 described in 20 further detail below. The frame 8 provides support for further components of the desalination unit 1. The desalination unit comprises a number of desalination membranes 20. In the embodiment described herein, there are ten desalination membranes 20, although other numbers can be used. The desalination membranes 20 25 can be any suitable desalination membrane such as those that operate using reverse osmosis. The use, operation and structure of desalination membranes is well known to persons skilled in the art and need not be described in any further detail herein, except as is relevant to the present invention. 30 The desalination membranes 20 are mounted within the frame 8 by means of upper and lower retention means 21, 22.

6 The upper retention means 21 comprises a plate 23 having two outer flanges 24 and a central flange 25 defining first and second channels 26, 27. The flanges 24, 25 strengthen the retention means 21, 22 so that they can hold the desalination membranes 20 without buckling. The upper and 5 lower retention means 21, 22 are arranged so as to be opposite to and substantially parallel to each other - as shown in Figure 5. The lower retention means 22 is constructed in the same way. Both of the upper and lower retention means 21, 22 have a plurality of circular apertures 28 provided along the lengths of the first and second 10 channels 26, 27. In the embodiment described herein, there are ten apertures 28: five in the first channel 26 and five in the second channel 27. The upper retention means 21 is supported in the frame 8 between the first upper pair of cross posts 14a, 14b and the lower retention means 22 is supported in the frame 8 between the second, lower pair of cross posts 15a, 15 15b with the respective first and channels 26, 27 facing each other and the apertures 28 are arranged so as to be substantially opposite each other such that one aperture in the upper retention means 21 and an opposite respective aperture in the lower retention means 22 defines a respective pair of circular apertures. 20 Opposing ends 29a, 29b of each desalination membrane 20 are received into respective opposing apertures in one of the respective pairs of circular apertures 28 so that the desalination membranes 20 are supported in a substantially vertical orientation and parallel to each other with regard to the frame 8 by the upper and lower retention means 21, 22 - as illustrated 25 in Figure 5. In the embodiment described herein ten desalination membranes 20 are supported by the frame 8 and the upper and lower retention means 21, 22 in this way - illustrated schematically in Figure 5.

7 Figure 3 is a schematic flow diagram illustrating the features of the desalination unit 1 and how bore water flows through the desalination unit 1 to provide fresh water at its outlet. Bore (or other unclean) water is fed into the desalination unit 1 via an inlet 5 30. The inlet 30 receives the water via an infeed line 31 connected to the bore pump 32. The use of bore pumps is well known to persons skilled in the art and need not be described in any further detail herein. From the inlet 30, the bore water is fed through the desalination unit 1 and in particular through a number of constituent features connected by 10 pipework 33 as will be described in further detail below. Typically, the pipework 33 is a combination of 25mm PVC materials and plastic plumbing fittings - as is well known to persons skilled in the art. From the inlet 30 the bore water passes to a pump 37 via an inlet solenoid 34 and an inlet transducer 38. The inlet solenoid 34 is operable to open and close to 15 control the flow of bore water as will be described in further detail below. The inlet solenoid 34 is coupled to a computer 35 and is arranged to receive control signals from the computer 35 to open and close the inlet solenoid 34 as required. The inlet transducer 34 (and indeed all the transducers provided within the desalination unit 1) is provided to measure water 20 pressure: low pressure indicating that filters may be blocked and need replacing/cleaning. Primary filters are filters provided external to the unit to filter water prior to it entering the unit. The computer 35 is coupled to a storage tank 36 for storing fresh water from the desalination unit 1 therein. The computer 35 monitors the level of 25 water stored in the storage tank 36 by any suitable sensor means (not shown) and when the amount of water stored in the storage tank 36 falls below a predetermined amount, the computer 35 is operable to determine that water is required to be produced by the desalination unit 1 and provides a signal to the inlet solenoid 34 to open and feed bore water 30 through the desalination unit 1. Any suitable solenoid or other valve means can be used. The operation of computers to provide the functionality described herein is well known to persons skilled in the art and need not be 8 described in any further detail herein, except as is relevant to the present invention. The computer 35 can be programmed using any suitable programming language and using any suitable operating system. A similar process could be used when the level in the storage tank 36 reaches a 5 maximum level to close the inlet solenoid 34. The pump 37 is operable to increase the water pressure to around 1800 KPa to enable the desalination membranes 20 to operate appropriately. From the pump 37 the high pressure water is passed to the desalination membranes 20 via a shut off valve 55 and a transducer 39. The shut off 10 valve 55 allows the amount of water being supplied to be regulated. The shut off valve 55 and the transducer 39 are both coupled to the computer 35 for the control and operation thereof. The bore water is thus passed under high pressure to the desalination membranes 20. As the water is passed through each desalination membrane 20, the 15 desalination membrane 20 separates out minerals and contaminants from the water, with the clean, fresh water passing through the desalination membrane 20 to freshwater outlets 40. The desalination membranes 20 operate using reverse osmosis. Any suitable desalination membrane 20 can be used. The operation of such membranes is well known to persons skilled 20 in the art and need not be described in any further detail herein. One example of a suitable membrane are those manufactured under the brand name CSM@ by Woongjin Chemical Company Ltd. As bore water enters a desalination membrane 20 at membrane inlet 45 it is filtered by the process of reverse osmosis with clean water being fed to 25 the respective freshwater outlet 40 of the desalination membrane 20. Waste water is fed to a waste water outlet 41; unfiltered water is then passed onto the next desalination membrane 20 via membrane outlet 46. The membrane inlets 45 to the desalination membranes 20 are via a larger red high pressure hose, and the outlets are from a clearer, thinner 12mm 30 poly tubing, generally situated in the centre of the top of the desalination membrane 20. Different numbers of membranes 20 are used for specific requirements. The number required is evaluated on the salinity level of the 9 bore water. If the number of membranes 20 required is odd, (as shown in Figure 3) then the initial entry of bore water to the desalination membrane 20 will be at the base of the desalination membrane 20, and the final outlets 41, 42 from the last desalination membrane 20 of the fresh water 5 and waste water, will be from the top of the desalination membrane 20. Should an even number of desalination membranes 20 be used, then the first and last inlets and outlets of the treated water will both be from the bottom of the respective membrane 20. Each waste water outlet 41 is connected to a waste water transducer 43 10 and shut off valve 44 (of which only one is shown in Figure 3, for clarity). The waste water transducer 43 is operable to measure the water pressure at this point and to feed this measurement to the computer 35. Data about the water pressure is sent to the computer 35 which is operable to control the shut off valve 44 in response. For clarity, the connections to the 15 computer 35 are not illustrated in Figure 3. The last shut off valve 44 allows back pressure to be placed on the water flow enabling a balance of the measure of waste water being produced to the measure of fresh water being produced, as is well known in the art Figure 7 is a schematic illustration of the connection 42 between adjacent 20 desalination membranes connecting the membrane outlet 46 of one desalination unit 20 to the membrane inlet 45 of the adjacent desalination membrane 2. As illustrated in Figure 7, the connection 42 is a semi-circular pipe made of 316 stainless steel. This semi-circular, arcuate, construction avoids loss of energy and reduction in pressure as the water moves from 25 one desalination membrane 20 to the next as happens in conventional right angled connections between desalination membranes. All of the waste water outlets 41 are connected to a waste water flow gauge 47 and from there to a waste water reservoir 48. The waste water is fed out of the desalination unit 1 to the waste water reservoir 48 in suitable 30 pipework through aperture 56 in the housing 2. The waste water flow gauge 47 operates as water flows through it in a known way using a floating 10 pin (not shown). This provides a visual indication via the respective display 10 of how much waste water is being generated during production. Similarly, the freshwater outlets 40 are coupled to a freshwater flow gauge 50 and from there to the storage tank 36. The freshwater is fed out of the 5 desalination unit 1to the storage tank 36 in suitable pipework through aperture 54 in the housing 2. The freshwater flow gauge 50 also operates as water flows through it in a known way using a floating pin (not shown). This provides a visual indication via the respective display 10 of how much freshwater is being generated during production. 10 Both the incoming bore water coming from the bore water inlet 30 and fresh water from the freshwater outlet 40 are sampled by a TDS ("total dissolved solids") monitoring device 51 to determine the quality of the freshwater outlet from the membranes 20. The TDS monitoring device 51 monitors the salinity level of the initial bore water being fed into the system 15 as well as the final salinity level of the water leaving, after it has been treated. There is no specific percentage reduction level being sought: the number of desalination membranes 20 are installed in the desalination unit 1 to bring the final result somewhere between 60-160 ppm. Should the TDS monitoring device 51 pick up that the levels are too high, 20 then additional membranes 20 need to be installed in the desalination unit 1. Any suitable TDS monitor can be used. A dosing pump (not shown) is provided that is a small pumping unit that siphons outside the unit 1 and is provided on the rear wall 5. Dosing pumps are known in the art. The dosing pump siphons from a container (not 25 shown) provided nearby the unit. While in operation it siphons a couple of milliliters each minute of an anti-scalent solution housed in a container nearby. This anti-scalent solution is added to the bore water before it passes through the membranes 20, inhibiting any prospective calcium, iron or silica build up in the membranes.

ll A facility to flush the desalination unit 1 is provided by connecting the storage tank 36 to the pipework 33 connected to the bore water inlet 33 via a flush feedline 49. The system is flushed at the end of every production cycle. A flush line solenoid 52 is provided to regulate the flow along the 5 flush feedline 49. The flush line solenoid 52 is connected to the computer 35 which is operable to send signals to the solenoid 52 to operate the solenoid 52 as required. Figure 6 illustrates how the frame 8 supports the pump 37, computer 35, TDS monitoring device 51 and flow gauges 47, 50. As illustrated in detail in 10 Figure 6, the flow gauges 47, 50 are held in place on the frame 8 using side angle brackets 53 so that it can be held in place flush with the front panel of the desalination unit 1. The TDS monitoring device 51 can be held in place using angled plates 54 and double-sided tape. The computer 35 can be mounted using side mounted brackets 55: again illustrated in the Figure 6 15 detail. The computer, pump, transducers, solenoids and valves are connected to an appropriate power source (not shown). Such connections are well known to persons skilled in the art and need not be described in any further detail herein. 20 Although the invention is described above with reference to specific embodiments, it will be appreciated by those skilled in the art that it is not limited to those embodiments, but may be embodied in many other forms.

Claims

1. A desalination unit comprising a plurality of desalination membranes provided in a housing wherein the desalination membranes are coupled to each other and arranged to receive unclean water at an inlet and 5 clean water at an outlet.

2. A desalination unit according to claim 1, wherein the desalination membranes are arranged in a substantially parallel orientation.

3. A desalination unit according to claim 1, wherein the desalination membranes are arranged in a substantially vertical orientation. 10

4. A desalination unit according to claim 1 or claim 2, wherein the housing includes upper and lower retention means for supporting the desalination membranes in the substantially vertical orientation.

5. A desalination unit according to claim 4, wherein each of the upper and lower retention means comprises a plate having a plurality of 15 apertures provided therein, the upper and lower retention means being supported within the housing so as to be arranged substantially opposite and parallel to each other so as to define respective pairs of opposing apertures for retaining opposing ends of the desalination membranes therein. 20

6. A desalination unit according to any preceding claim, wherein adjacent desalination membranes are connected together by connection means for feeding water from one membrane to the next, the connection means being of arcuate construction.

7. A desalination unit according to any preceding claim including means 25 arranged to receive a signal indicative of when the level of water in a remote storage tank below a minimum or above a maximum level and valve means operable in response to the signal to control the flow of water into the desalination means via the inlet. 13

8. A desalination unit according to any preceding claim, and further comprising means for measuring waste water pressure and valve means operable to control the flow of waste water in response thereto.

9. A desalination unit according to any preceding claims comprising 5 means for providing a visual indication of the amount of waste water produced by the desalination unit.

10. A desalination unit according to any preceding claim comprising means monitoring the total dissolved solids in clean water produced by the desalination unit. 10

11. A desalination unit in accordance with Figures 1 to 7.