This invention relates to a pressure exchanger, and more particularly, but not exclusively, to a pressure exchanger having improved efficiency and/or reduced production cost.
It is known to provide a pressure exchanger for use in reverse osmosis processes used within the water desalination industry, and in particular the seawater reverse osmosis desalination industry. For example, a rotary positive displacement pressure exchanger is disclosed in U.S. Pat. No. 7,251,557.
However, the applicant has identified that existing rotary positive displacement pressure exchangers are expensive, and are not suitable for use in applications with a relatively high proportion and size of particulate matter in the fluid flowing through the pressure exchanger.
Examples of the present invention seek to provide a pressure exchanger which overcomes or at least alleviates one or more disadvantages of previously proposed pressure exchangers.
In accordance with one aspect of the present invention, there is provided a pressure exchanger for transferring pressure from a high pressure fluid to a low pressure fluid, including a housing and a rotor arranged for rotation within the housing, the rotor having at least one passage extending generally axially through the rotor, the passage having a first opening at one end and a second opening at another end, the openings being mutually spaced along the length of the rotor, the housing having a plurality of ports at one axial portion for communication with the first passage opening and a plurality of ports at another axial portion for communication with the second passage opening, wherein the first passage opening is directed substantially radially, such that fluid is directed radially inwardly when entering the first passage opening and radially outwardly when exiting the first passage opening.
The first passage opening may be directed to have a tangential component as well as a radial component.
Preferably, the second passage opening is directed substantially radially such that fluid is directed radially inwardly when entering the second passage opening and radially outwardly when exiting the second passage opening.
In accordance with one aspect of the present invention, there is provided a pressure exchanger for transferring pressure from a high pressure fluid to a low pressure fluid, including a housing and a rotor arranged for rotation within the housing, the rotor having at least one passage extending generally axially through the rotor, the passage having a first opening at one end and a second opening at another end, the openings being mutually spaced along the length of the rotor, the housing having a first inlet and a first outlet located axially to correspond with the first passage opening, and a second inlet and second outlet located axially to correspond with the second passage opening, such that in one rotational position of the rotor the passage communicates with the first inlet and the second outlet, in another rotational position of the rotor the passage communicates with the second inlet and the first outlet, wherein the first passage opening is directed substantially radially such that in said one rotational position fluid is directed radially inwardly from the first inlet to the first passage opening, and in said other rotational position fluid is directed radially outwardly from the first passage opening to the first outlet.
Preferably, the second passage opening is directed substantially radially such that in said one rotational position fluid is directed radially outwardly from the second passage opening to the second outlet, and in said other rotational position fluid is directed radially inwardly from the second inlet to the second passage opening.
Preferably, the rotor has a plurality of like passages distributed radially about the axis of rotation. More preferably, the passages are distributed at equal radii and angular intervals about the axis of rotation.
Preferably, the or each passage is offset from a radial direction of the rotor such that the direction of entry and exit of the fluid (ie. a central line of the flow path) is spaced from the axis of rotation of the rotor. More preferably, the passage is curved inward of the openings to induce a change in direction of the fluid entering and exiting the passage, and the net reaction force from the changes in direction acts on a line of action that is offset from (does not intersect and is not parallel to) the axis to result in a torque driving rotation of the rotor. Even more preferably, the net reaction force acts in a plane perpendicular to the axis of rotation of the rotor. In other words, the direction of one or more passage openings includes a component of direction which is tangential relative to the rotor such that the central line of the flow path through each of said openings relative to the rotor is spaced apart from (does not intersect and is not parallel to) the axis of rotation of the rotor.
In one example, the inlets are arranged such that rotation of the rotor is driven by impulse of fluid entering the passage. Accordingly, rotation of the rotor is driven (or assisted) by the direction of flow of fluid entering the passage.
Preferably, the first inlet is opposite the first outlet, the second inlet is opposite the second outlet, and the passages are arranged in opposite pairs, whereby one side of the rotor transfers high pressure as the opposite side of the rotor transfers low pressure, the high pressure side biasing the rotor relative to the housing toward the low pressure side so as to assist in sealing of the openings at the low pressure side.
As an alternative the above may also be achieved with an odd number of passages which may assist to reduce resonance, noise and vibration that may occur with passages arranged in opposite pairs.
In a preferred example, the housing is made of a plurality of separate parts. More preferably, the housing includes two end caps, one end cap having the first inlet and first outlet, the other end cap having the second inlet and second outlet.
As an alternative, the inlets and outlets may be incorporated into the body of the housing with simple end plates closing each end of the housing.
Preferably, the first passage opening is oriented in a direction perpendicular to the axis of rotation of the rotor. Similarly, the second passage opening may also be oriented in a direction perpendicular to the axis of rotation of the rotor.
The invention is described, by way of non-limiting example only, with reference to the accompanying drawings in which:
The rotor 14 has a plurality of passages 18 extending generally axially through the rotor 14. Each passage 18 has a first opening 20 (see
In the example shown, the second passage openings 22 are also directed substantially radially such that fluid is directed radially inwardly when entering the second passage openings 22, and radially outwardly when exiting the second passage openings 22. Similarly, as shown in
Advantageously, by virtue of the first and second passage openings 20, 22 being directed substantially radially, the applicant has determined that it is possible to provide improved sealing between inlets and outlets of the pressure exchanger 10, with potentially greater tolerances and lower manufacturing costs, as well as inducing torque by virtue of the tangential component so as to drive the rotor 14.
With reference to
Accordingly, the rotor 14 rotates slidingly and sealingly within a sleeve 40 of the housing 12. The passages 18 within the rotor 14 connect the high pressure inlet 32 to the high pressure outlet 38 and the low pressure inlet 36 to the low pressure outlet 34. As the rotor rotates, fluid entering the high pressure inlet 32 fills the passages 18 connecting the high pressure inlet 32 and the high pressure outlet 38, pushing fluid that was in these passages 18 out through the high pressure outlet 38. As the rotor 14 rotates, the fluid is firstly sealed in these passages 18 by the close fit between the outer surface of the rotor 14 and the inner surface of the sleeve 40. As the rotor 14 continues to rotate, these passages 18 then connect the low pressure inlet 36 to the low pressure outlet 34. Fluid entering the low pressure inlet 36 fills these passages 18, pushing the fluid that was in these passages 18 out through the low pressure outlet 34. As the rotor 14 continues to rotate, the passages 18 are again sealed by the close fit between the outer circumferential surface 24 of the rotor and the inner surface of the sleeve 40. Finally, as the rotor 14 continues to rotate, having completed one revolution, the passages 18 in question again connect the high pressure inlet 32 to the high pressure outlet 38 and the above described process repeats itself indefinitely. This process occurs continuously for the many passages 18 in the rotor 14. Each passage 18 may be provided with a diaphragm or sliding seal to eliminate contact between the two fluids.
It will be understood by those skilled in the art that various methods may be used for fixing and sealing components of the housing 12 relative to other components of the housing 12 and lie within the scope of the present invention.
The pressure exchanger 10 may include thrust bearings (hydrodynamic or otherwise) to support the weight and/or hydrodynamic thrust of the rotor in axial directions.
If the fluid flow rates into the high pressure inlet 32 and the low pressure inlet 36 are equal (ignoring additional flow associated with leakage), the effect of the pressure exchanger 10 is that fluid flowing into the low pressure inlet 36 flows out the high pressure outlet 38 at increased pressure. Accordingly, there is an exchange of pressure from the high pressure fluid to the low pressure fluid.
With reference to
The high pressure inlet 32 and low pressure inlet 36 may be configured such that rotation of the rotor 14 is driven (or assisted) by the direction of flow of fluid entering the passages 18, in addition to the torque resulting from the change in direction of fluid in the passages.
As shown in the exploded views in
In one form the unbalanced pressure forces are resisted by hydrodynamic pressure forces in the close fit between the outer surface of the rotor 14 and the inner surface of the sleeve 40 which effectively acts as a hydrodynamic journal bearing.
Although the passage openings 20, 22 are shown in the drawings as being oriented in a direction perpendicular to the axis 42 of rotation of the rotor 14, it will be understood by those skilled in the art that the passage openings 20, 22 may be directed at other angles having a radial component while still falling within the scope of the present invention.
It will also be understood by those skilled in the art that integer multiples of the number of ports described in the preferred embodiments lie within the scope of the present invention and may be used to balance or mitigate unbalanced pressure forces.
Advantageously, examples of the present invention may provide a torque sufficient to drive the rotor 14 using only fluid forces, and may obviate the need for any mechanically or electrically powered rotation of the rotor 14.
It is foreseen that examples of a pressure exchanger in accordance with the present invention may be suitable for use in Dissolved Air Flotation, (and other lower water pressure applications), as well as in higher pressure applications such as seawater reverse osmosis desalination and brackish water reverse osmosis desalination.
Although the end caps 26, 28 (plates) shown in the alternative housing design have a screwed fit within the body of the housing (the housing ring 30), it will be understood that other means may be used for fastening the end caps 26, 28 to the housing ring 30. For example, in alternatives, this could be achieved with a ‘ring’ of bolts (as is the case with a blank flange), or many other possible means of maintaining the required fit.
With reference to
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.
Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge, in the field of endeavour to which this specification relates.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/AU2010/001573 | 11/23/2010 | WO | 00 | 6/25/2012 |
Number | Date | Country | |
---|---|---|---|
61264041 | Nov 2009 | US |