WO2005068044A1

WO2005068044A1 - Archimedian separator

Info

Publication number: WO2005068044A1
Application number: PCT/AU2005/000027
Authority: WO
Inventors: Stephen Horvath
Original assignee: Star Scientific Pty Ltd
Priority date: 2004-01-15
Filing date: 2005-01-15
Publication date: 2005-07-28

Abstract

An apparatus for separating a feed solution into a product solution of decreased concentration and an exhaust waste solution of increased concentration. The apparatus comprises: (a) a supply source of feed solution of water having contaminants for separation, (b) a supply line for feeding the feed solution from the supply source to the apparatus; (c) means for driving the supply source into the apparatus under pressure; (d) at least one inlet line for delivery under pressure of the feed solution to at least one feed solution separator. The feed solution is passed at a predetermined velocity through a stationary spiral formed in the at least one feed solution separator, sufficient to generate a centrifugal force on the feed solution which induces separation of the feed solution into the product solution of decreased concentration and exhaust waste solution of increased concentration.

Description

A CHIMED1AN SEPARATOR

BACKGROUND

This invention relates to separation apparatuses and more particularly to desalination apparatuses and more particularly relates to a process and apparatus in which a. fluid such as but not limited to water may be purified by centrifugation. More particularly the present invention relates to an apparatus and method for separating immiscible liquids or solids from Hqutds by the application of a centrifugal force to the liquid. More particularly the invention further provides an apparatus in which a centrifugal separation force may be generated by introducing a high velocity fluid stream into a spiral cavity having decreasing cross-section to producing a continuously increasing velocity.

The invention provides a method of producing high quality potable water at a greatly reduced cost using an Archiτπediaπ desalination assembly to be described herein.

PRIOR ART

There is no optimum or universal process for deroineralisation of the various feed waters. Each so-called contaminated or modified feed water supply must be evaluated for its peculiarities and optimal process for purification for a specific end use. As established by the U.S. Public Health Service, water for human consumption should contain no more than 300 to 500 parts per million, of dissolved solids. To achieve that a secondary purification process may be introduced, using known technology in the fbπn of reverse osmosis or thermal desalination combined with selective chemical and ultra violet treatments depending on the contamination of the feed water. The partial or almost complete demineralization of sea, and brackish waters, geothermat brines, wastewaters, and industrial effluents to make fresh water suitable for human or animal consumption, diverse industrial uses, irrigation, recreation or aquifer recharge is broadly referred to as desalination.

Desalination is a process of removing dissolved salts notably sodium chloride, from seawater, bore water and brackish water to yield potable water for human. consumption, iπigaiion and industrial purposes. As the earth's population grows, the demands on water resources increase not only by domestic consumption, but also an associated agricultural and industrial, water demand. Concurrentiy, water resources are being depleted by declining water tables, by pollution of surface sources, and the ever increasing salinity of ground and river waters.

While the plants for desalination of seawater, bore and brackish water are becoming economically competitive compared with the cost of transporting fi-esh water over long distances, the capital investments of the desalting plants which consume large quantities of energy and require continπous maintenance reduce its feasibility. In the mid Ϊ970's, there were approximately 700 desalination plants with a capacity totalling about 250 million gallons per day located throughout the industrial world. The largest of these is in the Netherlands, having a capacity of 7.5 million gallons per day. In various facilities,, e.g. plants and marine structures, agricultural land_* in inland areas, islands and desert regions, it is difficult to obtain suitable water for industrial use, drinking water or agricultural water, and in many cases, it is necessary to transport water by ship or truck or to lay water supply pipelines. Some desalination plants use, a membrane or other types of desalination apparatus that necessarily consume a large amount of electric energy. Thermal or nuclear power plants reuse high-temperature waste heat to generate electricity from steam turbines. Many plants or other facilities having a waste heat source as stated above require de ineralized water or water having a low impurity content to operate. The technique of transporting such water by ship, land vehicle or pipelines suffers from the problem that the cost of transportation, the construction costs and maintenance and management costs are high Membranes or other types of desalination apparatus consume a large amount of electric energy, and this also contributes to high operation costs.

In order to efficiently desalinate saline or hard water, vacuum evaporation type desalination apparatuses in particular, those which use a flash system or a multiple-effect can system have been proposed. Conventional flash or multiple- efifect desalination aj∑patatuses suffer from the disadvantage that the amount of water used for cooling in condensers is large, and the amount of water discharged is correspondingly large, resulting in the need for a great amount of pump power.

In a flash system, if the difference in temperature between a heat source used and cooling water is small, efficiency becomes low. The conventional multtple- effect system suffers from the disadvantage that if a temperature difference between a heat source used and cooling water is small, it is impossible to increase the number of cans used to form a multiple-effect desalination apparatus. Accordingly, it is difficult to improve efficiency.

Because both the systems use a continuous operation mode, it is necessary to run a fluid transfer pump and a vacuum pump at all times consuming a large amount of power, reducing efficiency. A large capacity vacuum pump which consumes a large amount of power is required.

In the past, several processes for removing salt from water have been proposed, of these, distillation is the oldest and the most common desalination process employed. The principal previously known processes used may be summarised as follows:

Flash Desalination; Multiple-effect Multistage Flash Desalination; Vapour Reheat Flash Desalination; Multiple-effect Evaporation Vapour Compression Desalination; Solar Desalination; Humidificaπon. Solvent Extraction;

ElecUodialysis; Reverse Osmosis; Hydzate process; .Direct Freezing - Vapour Compression; Direct Freezing Secondary Refrigeration Exchange.

Thus, in the past a diversity of approaches were used for the separation of water from saline solutions. Thermal processes effect separation by means of phase changes and include distillation and freezing processes. In the membrane processes, one or more suitably designed organic membranes accomplish, the separation process. In a single membrane design, reverse osmosis pressure forces the fresh water through the membrane. In electrodialysis, a system using multiple membranes and direct current leads to formation of pure water and brine streams and drives the salt ions toward the electrodes through charge- selective membranes. In the ion exchange process, substances are added to exchange the ions in the solution or to precipitate the salts. There are also chemical processes, la the solvent extraction process, chemicals with greater affinity for water can remove the wastes from solutions.

As an alternative to the abovemeotioned processes _sin recent years several new .f approaches have been investigated, namely hydrocyclone, rotary vacuum distillation and desalination such as are disclosed in the following patents / patent applications which are incorporated by reference herein: WO 02/076622

Al, US5337899, US 6436298, US 2002/0189987, US 5534118, US 6500345 and UK 812,89.1, However, none of the processes described in those documents are able to reduce the initial investment cost or to diminish the continuous maintenance needed to maintain an economic operation. United States Patent 4,230,564 discloses a rotary reverse ultrafihtation osmosis apparatus ahd method having first and second rotors revolving in the same direction about a central axis. The first rotor revolves at a higher speed and has an impeller which serves as a feed pump for the feed fluid. The second rotor revolves at lower sf>eed and has a pressure vessel containing semi-permeable membranes which selectively permeate one component of a feed fluid, and has an integral diffuser casing for the feed pump. This arrangement reduces disc friction and diffiiser hydraulic losses compared to conventional centrifugal machinery with stationary casings. The membranes are arranged so that centrifuge action within the rotating membrane assembly inhibits fouling and concentration polarization by differential buoyancy effects. The impeller can be centrifugal type with an. externally surrounding diffuser, or it can be in an external impeller type enclosing a pitot tube pump type difluser. Concentrate fluid energy can be recovered by using tangentially disposed nozzles mounted on die second rotor to discharge fluid backwards. Permeate fluid energy can be recovered from permeate nozzles ejecting permeate fluid against an impulse turbine mounted on a third rotor journalled to rotate about the axis at a speed of about one-half of the speed of the second rotor. One disadvantage of this arrangement is that it has a complex system of moving components and is expensive to maintain and qperate.

In another example of a prior art system, United States Patent 4,333,832 discloses a rotating solution separation system, wherein salt water and other solutions are accelerated in a rotating structure and applied to a cannister containing reverse osmosis membrane material. The desalinated water is removed after passing through the large surface area concentration of membrane material in the cannister. The enriched brine is removed from the cannister at a point furthest from the axis of the rotating structure and returned to the vicinity of the axis to prevent the build up of dense material. The membrane material is configured in di cannister so that the flow is generally radial with respect to the axis of die rotating structure. This arrangement alsrø has the disadvantage that it is expensive to operate and to maintain due to the use of moving parts.

In an example of known reverse osmosis desalination, United States Patent 4,886,597 discloses a centrifugal reverse-osmosis desalination apparatus for removing salt from seawater. The apparatus operates on the principle of reverse- osmosis whereby a feed solution containing seawater is separated into a product solution of decreased salt concentration and an exhaust solution of increased concentration. An evacuated enclosure is included to reduce windage losses and power consumption. Reverse-osmosis is a high, pressure process, e.g., 800 ps in the case of desalination of seawater. Traditionally, there have been two techniques for developing this high pressure, namely, high pressure pumps and centrifuges. Althoiqjh a centrifuge ofifere theoretically higher efficiencies, commercial systems, almost without exception, have employed pumps. Practical difficulties have prevented widespread development of centrifugal reverse-osmosis desalination systems. One of these difficulties is the design of a membrane configuration suitable for a centrifuge. For example, U.S. Pat No. 3,669,879 proposes various means for deploying a reverse-osmosis membrane within a single cylindrical rotating pressure vessel.

U.S. Pat No. 4,333,832 by Siwecki et al employs, on the other hand, a number of smaller pressure -vessels located about the periphery of a rotating structure or rotor. Each vessel <:oniains a single cartridge of reverse-osmosis membrane material. This is a practical design but ft is feasible only for relatively targe rotor diameters.

Desalination aπangtsments have been proposed wherein a single solution is separated by means of a reverse-osmosis membrane, into two solutions; one of higher and one of lower concentration than the original solution. In another example of the prior art apparatuses, United States Patent 5,137,637 discloses a rotationjd high flux membrane device comprising a spiral wound membrane module for use in separating at least part of one component from a feed stream, the module comprising: a generalry-hoHow rotatable shaft having a means for supplying a feed stream; a means capable of rotating the shaft about its axis of rotation; two permselective membranes affixed to the shaft and spaced from each other by a permeate spacer to provide a first membrane channel therebetween; a feed spacer disposed about the exterior surfaces of the permselective membranes such that a second membrane channel is formed when the permselective membranes are spirally wrapped around the shaft in overlapping relationship one upon the other to form a compact membrane roll; a means for removal of a permeate stream from the first membrane channel to the exterior of the membrane module; and a means for removal of a retetitate stream from, the second membrane channel to the exterior of the membrane module.

The apparatus described in that patent is complex to operate an manufacture and has a large number of moving parts which require high maintenance. This makes the apparatus expensive to construct and maintain thereby reducing the overall economic efficiency of. the system. Also, the system requires membranes for separation of the unwanted effluent from the product and involves spinning of the membranes disposed about a shaft.

United States Patent 6,833,056 discloses a desalination method and desalination apparatus capable of obtaining fresh water siably at alleged low cost by utilizing low-temperature waste, wherein the desalination apparatus includes a heat exchanger cooperating with an evaporation can so as to subject a low- temperature waste h<jat and raw water in the evaporation can to heat exchange and generate water vapour in the evaporation can; a. condenser cooperates with a raw water tank so as to receive the water vapour from the evaporation can , cool the water vapour by subjecting the water vapour and raw water in the raw water tank to heat exchange and obtain distilled water, a distilled water tank for storing the distilled water ; vacuum means for evacuating the evaporation can and depressurizing the inside thereof so as to promote generation of water vapour in the evaporation can ; and raw water supply means for supplying raw water to the evaporation can.

United States Patent 6,132,613 discloses a Centrifugal reverse-osmosis desalination unit incorporating an annular membrane cartridge This invention relates to an apparatus for separating an original feed solution such as seawater into a product solution of decreased concentration (relatively fresh water) and an exhaust solution of increased concentration. The apparatus includes an annular reverse osmosis membrane means, contained in an annular pressure vessel that is housed in a rotor assembly. The rotor is arranged to spin on an axle and is located within an evacuated shroud. The apparatus further includes supply means for supplying the original feed solution to the reverse osmosis membrane, exhaust means at an outermost radius of the reverse osmosis membrane for removing the exhaust solution from the reverse osmosis membrane, product removal means at an innermost radius of the reverse osmosis membrane for removing the product solution from the reverse osmosis membrane and means for creating a pressure differential across die reverse osmosis membrane to separate the original feed solution into the product solution and the exhaust solution. The supply means and the exhaust means are relatively axially and radially spaced such that the feed solution travels along a combined radial and axial flow-path. It øiay be seen from the above examples of the prior art methods and apparatuses for desalination, that many employ complex structures which are expensive to construct, run and maintain. Also the known apparatuses employ moving parts such as single and contra spinning rotors which due to high maintenance contribute to overall inefficiency of the known systems. INVENTION

The present invention seeks to overcome the problems of the prior art apparatuses and methods for fluids separation and particularly though not limited to desalination by providing a process and associated apparatus which provides efficient and cost effective desalination, and with no moving parts. This invention provides an apparatus and method for separating immiscible liquids or solids from liquids by the application of a centrifugal force to the liquid usin a centrifugal separation force generated by introducing a high velocity fluid feed stream, into a separation unit including a spiral passage having decreasing cross-sectign for producing a continuously increasing velocity as the feed stream proceeds along the passage. Although the invention will primarily be -described with reference to its application to desahnation, it will be recognised that desalination is but one example of the application of the system and apparatus of the invention to be described herein. For instance the apparatus may be used in the separation of viscous liquids from, non or less viscous.

Throughout this specification, reference to a feed solution should be taken as a reference to a contaminated solution from which is to be separated contaminants" such as but not limited to sodium chloride. A reference to product is a reference to a solution having reduced contaminants or all contaminants removed. A reference to exhaust is a reference to a solution, havmg contaminants which is discharged from the desalinator.

To overcome, the restraints created by the processes mentioned above a new approach is needed, which is embodied in the description of the process and apparatus relating to the desalination of feed water for which the following are the objectives. It is one objective of the present invention to provide a process for separating a mixture of a less dense liquid and a more dense liquid component by the application of centrifugal force inside a stationary apparatus by introducing a high velocity fluid stream into a horizontal Archimedian . spiral like cavity having a decreasing cross-section thus generating a continuously increasing velocity..

It is still a further object of the present invention to apply the aforesaid arrangement for desalination of seawater, bore water and brackish water to irrigation water puril containing no more than 600 to SOOppm dissolved solids.

It is another objects of the present invention to provide a process and apparatus which will yield polable water for human consumption and which contains no more than 300 parts per million of dissolved solids.

It is yet another object of the present invention to provide a process and apparatus capable of supplying high purity industrial water.

Finally, it is another object of the present invention to provide a practical application of the Archimedian Desalinator, which will reduce if not eliminate the continuous maintenance needed to support an economic desalination operation. It is another object to provide a system and apparatus for desalination and to reduce the initial investment cost and provide a clean, environmentally friendly, cheap, dependable desalination operation. According to one a pect of the invention there is provided an apparatus for separating an original feed solution into a product solution of decreased contaminant concentration and an exhaust solution of increased concentration.

Jta its broadest form the present invention comprises: an apparatus for separating a feed solution into a product solution, of decreased concentration and an exhaust waste solution of increased concentration, the apparatus comprising:

(a) a supply source of feed solution of water having contaminants for separation,

b) a supply line for feeding said feed solution from the supply source to said apparatus;

c) means for driving said supply source into said apparatus under pressure;

d) at least one inlet line for delivery under pressure of said feed, solution to at least one feed solution separator

wherein, said feed solution is passed at a predetermined velocity through a stationary spiral formed in said at least one feed solution separator, sufficient to generate a centrifugal force on said feed solution which induces separation of the feed solution into said product solution of decreased concentration and exhaust waste solution of increased concentration.

In another broad foπn the present invention comprises:

An apparatus for separating a feed solution into a product solution of decreased concentration and an exhaust waste solution of increased concentration, the apparatus comprising:

(a) a source of feed solution of water having contaminants for separation,

b) a supply line for feeding said feed solution from a supply source to said apparatus;

c), a pressure vessel

d) at least one inlet line for delivery of said feed solution to ihe pressure vessel under pressure; e) a desalinator retained on the pressure vessel and including a base, a cover and sealing means;

f support means for supporting said pressure vessel;

wherein said feed solution is passed through the desalinator via said pressure vessel with sufficient velocity to generate a centrifugal force on said solution which induces separation of the feed solution into said product solution of decreased concentration and exhaust waste solution of increased concentration.

Preferably the desalinator includes a bore which receives and retains -therein said pressure vessel. The desalinator further comprises a generally annular shaped main body and an internal horizontal spiral passage of gradually increasing radial extent which receives the feed solution. Preferably the spiral passage has a decreasing cross section along its length from the at least one inlet. Preferably, the decreasing cross section of the spiral passage produces a continuously increasing velocity of said feed solution as it travels along the spiral passage.

According to one embodiment the main body of the desalinator has a stepped centre core to which a plurality of ribs are attached. The bore of the desalinator enables said pressure- vessel and said desalinator to meet in slidable engagement anywhere along the length of the pressure vessel . According to a preferred embodiment, a working pressure of said pressure vessel is around half the design pressure of said pressure vessel.

The base of the desalinator has sufficient depth to provide said spiral passage as an Archimedian spiral wherein the spiral is represented in polar co ordinates by the formula r - a 9. The desalinator includes an exhaust port for discharging waste material separated from the feed solution. The desalinator also includes an exhaust port for discharge of feed solution with waste material, removed.

Preferably, the exhaust port for the waste material is oriented at a tangent to a circumference defined by one spiral of the spiral passage of the desalinator. According to a preferred embodiment the exhaust port for the discharge of the feed solution with waste removed is disposed at an outermost radial extent of the spiral passage. The support assembly includes support plates and the feed solution travels along a combined spiral and radial flow-path.

In a further broad form the present invention comprises:

a separator for use in a separating apparatus for separating a feed solution into a product solution of decreased concejn,tration and an exhaust waste solution f increased concentration, the apparatus comprising:

(a) a source of feed solution of water having contaminants for separation,

c). a pressure vessel

d) at least one inlet line for delivery of said feed solution to the pressure vessel under pressure;

the separator being retained on the pressure vessel and including: a base, a cover and sealing means;

a bore which receives and retains therein said pressure vessel; the separator further comprising;

a generally annuar shaped main body; and

having an internal horizontally disposed spiral passage of gradually increasing radial extent which receives said feed solution;

wherein said feed solution is passed through the separator via said pressure vessel with sufficient velocity to generate a centrifugal force on said solution which induces separation of the feed solution into said product solution of decreased concentratson and exhaust waste solution of increased concentration. In another broad form of a method aspect, the present invention comprises:

a method for desalination of salt water using an apparatus for separating a feed solution into a product solution of decreased concentration and an exhaust waste solution of increased concentration, the apparatus comprising;

c) means for driving said supply source into said apparatus under pressure;

d) at least one inlet line for deliveiy under pressure of said feed solution to at least one feed solution separator

the method comprising the steps of:

a) passing the feed solution at a predetermined velocity through a stationary spiral formed in said at least one feed solution separator,

b) allowing the feed .solution, to travel through the spiral generating a centrifugal force sufficient to induce a separation in the feed solution;

c) causing the product solution of decreased concentration to exit the spiral via an outlet;

d) causing the exhaust waste solution of increased concentration to exit the spirat via another outlet

According to a preferred embodiment the method comprises the further step of; providing a slit upstream of said outlets and adjusting the slit to ensure to allow separate discharge from the spiral of the product solution of decreased concentration and the exhaust waste solution of increased concentration. The slit may be adjusted to allow separate discharge from the spiral of the product solution of decreased concentration and the exhaust waste solution of increased concentration irrespective of the velocity of the feed solution through said spiral..

BRIΕF DESCRIPTION OF THE DRAWINGS.

The present invention will be described in more detail with reference to a ϊ 0 preferred but πon limiting embodiment and with reference to the accompanying illustrations. Attention is now directed to Figures 1 to 4, which display various features characterising a preferred embodiment of the invention; wherein; Figure I ^' shows an elevation view of an apparatus for desalination according to T 5 a preferred embodiment; Figure 2 shows a top plan view of the apparatus of figure 1 ; Figure 3 shows an exposed view of the Archimedian spiral slit and seal arrangement according to a preferred embodiment ; and Figure 4 shows a schematic layout of a desalination assembly according to a 20 preferred embodiment

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

25 Referring to figure 1 there is shown an elevation view of an apparatus t for use in a desalination assembly according to a preferred embodimen Apparatus 1 comprises a pressure vessel 2 having a first end 3 and second end 4. Second end 4 terminates in a support assembly 5 which comprises a prefabricated cylindrical support 6 retained by base plate 7 which is preferably festened to a

30 ground surface or platform 8 via fastener 9 which engages jock washer 10. It will be appreciated by peisons skilled in the art that multiple fasteners 9 may be used according to load resisting requirements on apparatus 1. Preferably fasteners 9 are bolts. Support assembly S includes reinforcing flanges 11 and 12 which are attached to base plate 7 which is preferably circular and to which is attached the flange^ 1,1. and 12. Flanges 11 and 12 are preferably tapered inwards from the base plate 7 and upwardly and provide stability to apparatus J.,

Assembly 5 includes a cylindrical location sleeve 13 which receives and retains therein pressure vessel 2, Tapered flanges 11 and 12 are attached to and retain location sleeve 13 which is preferably a headed bush like component having a circular flat upper surface thus providing a suitable location for pressure vessel 2 and separation/desalination unit 14 . The support assembly 5 may be made from mild steel provided that it is protected against corrosion.

The cylindrical location sleeve .13 also provides means of support for pressure vessel 2 which will preferably be cylindrical. Cylindrical pressure vessel 2 includes torispherical end caps 15 and 16 and is manufactured in accordance with prescribed pressure vessel standards. Pressure vessel 2 will contain the highly pressurised feed solution (such as seawater, bore water or brackish water) so the design pressure of vessel 2 should be about twice the working pressure needed to accomplish the required maximum (increasing) velocity of the feed solution. The vessel 2 is continuously pressurised and the internal design of the vessel \& such that it reduces, if not eliminates, turbulence of feed water during the continuous operation.

The pressure vessel 2 comprises a feed water inlet assembly 20 comprising inlet pipe 21 and attachment locking connector 22. Locking connector 22 is preferably a stainless steel HY-Lok male connector located in the centre of the pressure vessel 2 which will ensure an outstanding lock-tight connection for the stainless steel feed water inlet pipe 21. Adjacent to the feed water inlet assembly

20 is a HY-Pro high pressure relief valve 23 preferably having a cracking pressure within the range of 1550-5150 kPa, The valve 23 material is preferably stainless steel with a Viton seal The relief valve 23 is preset to the maximum allowable pressure and upon reaching the said pressure it will bleed to atmosphere via a bleed pipe 24 which is preferably stainless steel The HY- Pro relief valve 23 is the preferred valve, however, any suitable valve which can withstand the harsh pressures and environment may be used. Pressure vessel 2 further comprises an output line or feed pipe 25 which preferably engages and co operates with a stainless steel HY-Lok male connecto 26. To maintain, near uniform back- pressure the feed pipe output 25 must be marginally smaller than the feed water input line 21. Pressure vessel 2 also includes a stainless steel drain plug 27.

As mentioned before the pressure vessel is manufactured according to a prescribed Standard, with the preferred material of construction stainless steel 316. However, any suitable material may be used provided it is capable of withstanding the erosion caused by the feed water (seawater, bore water or brackish water).

Referring to figure 2 there is shown a top view of the apparatus of figure I with corresponding numbering. The pressure vessel 2 comprises a feed water inlet assembly 20 comprising inlet pipe 21 and attachment locking connector 22.

Locking connector 22 is preferably a stainless steel HY-Lok male connector located in the centre of the pressure vessel 2 which will ensure an outstanding lock-tight connection for the stainless steel feed water inlet pipe 21. Adjacent to the feed water inlet assembly 20 is HY-Pro high pressure relief valve item 23 .

As indicated, the valve 23 material is preferably stainless steel with a Viton seaL The relief valve 23 is preset to the maximum, allowable pressure and upon reaching the said pressure it will bleed to atmosphere via bleed pipe 24 which is preferably stainless steel. The HY-Pro relief valve 23 is the preferred valve_> however, any suitable valve which can withstand the harsh pressures and environment may be used. Output line 25 preferably consists of a stainless steel HY-Lok male connector 26.

Referring to figure 3 there is shown desalination unit 14 which includes an Arehimedian spiral 28 and is typified by having no moving parts. The desalination unit 14 comprises three main components, namely desalinator base X 29, desalinator cap item 30 and the seal 31 ( see figure 1 ) .

The desalinator base 29 consists of a hollow disc shaped main body 33 having a stepped bush like centre core 34 to which a number of ribs 35 are joined, thus supporting and strengthening the base 29. The bore 37 of tile centre core 34 of desalination, unit 14 allows a slide fit with the pressure vessel item 2 thus providing a suitable vertical location for the Archimedian spiral desalination assembly which is held relatively solid by a number of socket set screws 32. The smooth upper surface of the disc shaped body 33 must be perpendicular to the protruding part of the centre core which is partially threaded to matoh lock nut 38 ( see figure 1) . The disc has Sufficient depth to embody the Archimedian spiral like cavity 36 whic is a special spiral, represented in polar co-ordinates by r = a 0. The spiral, may be described as tfie locus of a point moving with uniform velocity along the radius vector, while the radius yector also moves about with constant angular velocity. The evolute of this spiral approaches asymptotically to a circle with radius a. Accordingly, if sufficient back pressure is maintained to develop the high velocity needed to force the feed water along a highly polished Archimedian spiral like cavity 36 with a continuously increasing velocity the centrifugal force will manifest itself. It is known that because of the polarity of solid salt, water can easily dissolve it. For example, when an NaCl (Sodium chloride) salt, is dissolved into water, it is separated into its component ions, Na-t- and CI- because of the water polarity. These ions move away from the salt crystal and fit into the gaps of the H2 chains. Therefore, the contaminated H2O chains density will increase, thus separation by centrifugal force will become feasible. In brief, the Archimedian spiral desalination assembly will act as a centrifuge, an apparatus which uses the centrifugal effect to separate solids from liquids, liquids from other liquids. Thus it is capable of desalinating sea water, bore or brackish water as stated above.

In the construction of the spiral cavity the pitch minus the breadth of spiral cavity 36 will leave a solid separation wall having sufficient width to embody a spiral like groove 39 which contains the separation seal. 31 (see Figure 1). The separated spiral cavity 36 begins close to di centre core 34 as shown by figure 3 and progressing in the direction of the arrow 40 spirally and radially to an outermost cavity 36* where an adjustable slit 41 is constructed which will induce the separation, of the potable water from the brine. The position, of the slit

41 relative to the cross section of the cavity 36 controls the purity of the potable water. The purity is maintained by the continuously decreasing cross-section of the spiral cavity which maintains the increasing velocity.

The velocity of the iluid stream flowing in cavity 36 to 36* increases up to the leading ( upstream) edge of slit 41 , At leading edge 41a of slit 41 a separation occurs between the product and exhaust, waste. The exhaust is urged by centrifugal force against a radially outermost wall 36b of cavity 36 creating an essentially vertical division between the product and the waste. When the separation occurs th« pressure locally decreases and the separated exhaust brine will exit the desalinator 14 device via an exhaust port 43. The bulk of the feed water introduced into the desalinator 14 which is potable following the separation, will depart the device through an outlet 42. The brine exhaust port

43 is connected to stainless steel pipe 44 preferably _*via a l4Y-Lok male connector He 45 (see Figure 2). Figure 2 also exhibits the potable water outlet

42 which terminates in a suitable stainless steel outlet pipe 46 which consists of an HY-Lok male connector 47 . To maintain a leak tight separation between the cavities 36 to 36a formed by the Archimedian spiral, a suitable sealing element such as but not limited to a Nitrile cord is employed to form seal 31 disposed in spiral groove 39 which may be vulcanised or cold joined with Cyaooacrylate. The pressure needed to compress the seal. 31 is derived by the desalinator cap 30 which is fastened in position by use of a number of drilled and tapped holes 49 as shown by Figure 3 and suitable bolts 50 which are secured block nuts 51.

The construction of the desalinator cap 30 comprises a hollow disc shaped main body 52 having a bush like centre core 53 to which a number of ribs 54 are joined and extend radially (see Figure 1). The bore 37 of the centre core _.34 is slidably fitted on thet stepped bush centre core of the base 29 of desalinator 14, The smooth surface of the cap 30 is perpendicular to the bore of the centre core and provides a close fit to desalinator base 29, A number of equally spaced holes located opposite the drilled and tapped holes as well as the lock nut 38 will maintain the pressure and the position of base 29 relative to cap 30 and desalinator 14 relative to pressure vessel 2. The feed water outlet 25 from pressure vessel 2 provides an inlet to desalinator 14 through the disc shaped main body cover 30 directly opposite to die beginning of the Archimedian spiral cavity 36 in base 29 nd connected via a stainless steel HY-Lok male connector 55 ( see figure 2). Feed water travels in outlet pipe 25 in the direction of arrow S6. The preferred material for the desalinator base 29 and the desalinator cap 30 is stainless steel 31.6, however, any suitable material including industrial ceramic may be used provided it is capable of withstanding the potential erosion caused by the various feed waters which may pass through the assembly 1. The desalinator base 29 and cap 30 respectively will preferably rest on support assembly 5 which includes an Ertalyte buffer which is placed in between the support iissembly 5 and the desalinator base 29 , Figure 4 shows a schematic layout of a system including desalination assembly 1 incorporated into a desalination unit according to a preferred embodiment. The construction of the Archimedian Desalinator assembly 1 has been previously described so it remains to describe how the assembly 1 may be incorporated into a desalination system, according to one non limiting embodiment. Figure 4 shows a system from start to finish in which potable water is produced from a feed ater supply. The schematic diagram of the desalination process must be read as an example and it is to be understood that various alterations, modifications and or additions may be incorporated into the construction and arrangements of parts without departing from the spirit or scope of the inventioα. A feed water supply indicated by arrow 60 i$ introduced into manually operated stainless steel gate valve 61 located in feed line 62- A low pressure feed water 60 is screened to protect, a vertical multistage centrifugal pump item 63. Pump 63 is an enetgy efficient high performance multi-stage pump activated by a control computer <?4 via the controller 65.

The pump 63 preferably will operate with constant flow and pressure. However, the pressure requirements of the desalinator assembly 1 will vary depending on the salinity concentration of the feed water 60 which is continuously monitored by a salinity transducer 66. The minimum pressure needed to desalinate the feed water 60 is fixed. Where the salinity of the feed water increases, the control computer 64 will via the controller 65 energise an actuator 67 incorporating an integral bonnet needle valve 68. The motorised actuator 67 provides an external closed feedback control and compensates for variation in flow and pressure. The control computer 64 is pre- programmed to a required feed pressure to match the feed water salinity. Upon reaching the preset pressure level, a pressure transducer 69 will transmit a signal to computer 64 , which in turn will stop and maintain the actuator 67 in the required position for feedback control. Tf the salinity of the feed water changes, the control computer will automatically reset the pressure. Furthermore, the control computer 64 is programmed to monitor the highest permissible salinity level of the potable water which is checked by a salinity transducer 70. If the salinity level is higher than prescribed, the control computer 64 will render the system inoperative until the operating parameters are recalibrated. The system further comprises an electromagnetic flowmeter 71 ensuring continuous accuracy ajnd providing a means to record output of the Archimedian Desalinator assembly l.

The centrifugal force exerted by the rotating mass and the increasing velocity of the feed water, is derived by the feed pressure used in the process. The outward force on the particles Mating about the axis, which by Newton's Third Law is equal and opposite and as such has a magnitude equal to and a direction opposite to the centripetal force. Therefore, the reaction force exerted by the centrifugal force, which is Mw R in a direction away from the centre of rotation is capable of separating heavy particles, a more dense liquid and a less dense liquid components by a carefully constructed adjustable slit 41 located tangential to an outmost diameter on the Archimedian spiral cavity 36a.

By the application f the described process in a stationary apparatus feed water such as seawater, bore water or brackish water can be desalinated to provide irrigation water with purity of 600 to SOOppm.

In order to highlight the practical application of the process and apparatus, attention should be directed to the simplicity of the Archimedian Desalinator construction. As stated previously the apparatus contains no moving parts thus continuous maintenance is eliminated and an economic operation is assured. To highlight its economy the following example is provided, tf the electrical input of the Desalinator is 15kw its output is 400,000 litres per day which may be increased or decreased at will.

The assembly may according to one embodiment, be set up as a multiple tiered apparatus in which, there are multiple separation or desalination stations in series or parallel and which allows treatment of one or multiple supply streams concurrently or selectively individually.

While the invention has been described concerning specific embodiments thereof and in a specific use, various modifications thereof will occur to those skilled in the art without departing from the spirit and scope of the invention as set forth herein. The terms and expressions employed in the specification are used as terms of description and not of limitations, and are not intended to exclude any equivalents of the features shown and described or portions thereof Nevertheless, it is recognized that various modifications are possible within the scope of the claims to the invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An apparatus for separating a feed solution into a product solution of decreased concentration and an exhaust waste solution of increased concentration, the apparatus comprising;

b) a supply line for feeding said feed solution from the supply source to said apparatus;-

c) means for driving said supply source into said apparatus under pressure;

d) at least one inlet line for deliveiy under pressure of said feed solution to at least one feed solution separator?

wherein, said feed solution is passed at a predetermined velocity through a stationary spiral formed in said at least one feed solution separator, sufficient to generate a centrifugid force on said feed solution which induces separation of the feed solution into said product solution of decreased concentration and exhaust waste solution of increased concentration.

2 An apparatus according to claim 1 wherein the feed solution travels from a first proximal end of the spiral in communication with the inlet to a second distal end of die spiral in communication including at least one outlet

3 An apparatus according to claim 2 wherein the spiral passage which receives said feed solution m the at least one separator is horizontal and of gradually increasing radial extent

4 An apparatus according to claim 3 wherein the spiral defines a cavity haing varied cross section along its length.

5 An apparatus according to claim 4 wherein the spiral cavity has a decreasing cross-section along its length. 6 An apparatus according to claim 5 wherein, the cross section of the spiral cavity decreases along its length from the at least one inlet to the at least one outlet

7 An apparatus according to claim 6 wherein the decreasing cross section of the spiral passage produces a continuously increasing velocity of said feed solution as it travels along the spiral passage.

8 An apparatus according to claim 7 wherein said pressure of the feed solution is induced through a pressure vessel in communication with said at least one separator.

9 An apparatus according to claim 8 wherein, the at least one separator is retained on the pressure vessel.

10 An apparatus according to_^ claim 9 wherein; die assembly comprises one separator which functions as a desalinator.

1.1. An. apparatus according to claim 10 wherein the desalinator includes a generally annuar shaped main body comprising a base, a cover and sealing means,

12 An apparatus according to claim 11 wherein the spiral cavity in the desalinator is defined by a spiral groove in the base and an opposing surface on the cover.

13 An apparams according to claim 12 wherein, a spiral sealing means is disposed adjacent said spiral cavity such that in cross section the seal separates adjacent passages of said spiral cavity,

14 An p aratus according to claim 13 wherein, the desalinator includes a ceniral bore which receives and retains therein said pressure vesseL 15 An apparatus according to claim 14 wherein, the main body of the desalinator has a stepped centre core to which a plurality of ribs are attached.

1 An apparatus according to claim 15 wherein, the central bore of the desalinator enables said pressure vessel and said desalinator to meet in slidable engagement anywhere along the length of the pressure vessel .

17 An apparatus according to claim 16 wherein the base of the desalinator has sufficient depth to provide said spiral cavity as an Archimedian spiral.

18 An apparatus according to claim 17 wherein the spiral cavity is represented in polar co ordinates by the formula r = a©where r is th e radius, a is the cross sectional area of the cavity and θ is an angle subtended from a centre of the desalinator.

19 An apparatus according to claim 18 wherein the desalinator includes an exhaust port for discharging waste material separated from the feed solution.

20 An apparatus according to claim 19 wherein the desalinator includes an exhaust port for discharge of feed solution with waste material removed.

21 An apparatus according to claim 20 wherein the exhaust port for die waste material is oriented at a tangent to a circumference of said desalinator taken at any radial distance from the centre of the desalinator,

22 An apparatus according to claim 21 wherein the exhaust port for the discharge of the feed solution with waste removed is disposed at an outermost radial extent of the spiral passage.

23 An apparatus according to claim 22 wherein said feed solution travels along a combined spiral and radial flow-path. 24 An. apparatus according to claim 23 further comprising support means for supporting said pressure vessel.

25 An apparatus according to claim 24 wherein the support assembly includes support plates.

26 An apparatus according to claim 25 wherein a working pressure of said pressure vessel is around half the design pressure of said pressure vessel,

27 An apparatus according to any of the foregoing claims wherein, a divi ing slit is disposed at or near said outlet to said spiral to fecili ate discharge of product from one said outlets and waste exhaust from a second outlet.

28 An apparatus according to claim 27 wherein the slit is adjustable to ensure separation just prior to discharge of product solution and exhaust solution.

29 A separator for use in a separating apparatus for separating a feed solution into a product solution of decreased concentration and an exhaust waste solution of increased concentration, the apparatus comprising:

(a) a source of feed solution of water having contaminants for separation,

c). a pressure vessel

d) at least one inlet 1 irte for delivery of said feed solution to die pressure vessel under pressure?

the separator being retained on the pressure vessel and including: a base,, a cover and sealing means;

a bore which receives and retains therein said pressure vessel; the separator further comprising; a generally annuar s aped main body; and

having an internal horizontally disposed spiral passage of gradually increasing radial, extent which receives said feed solution;

wherein said feed solution is passed through the separator via said pressure vessel with sufficient velocity to generate a centrifugal force on said solution which induces separation of the feed solution into said product solution of decreased concentration and exhaust waste solution of increased concentration.

30 A separator according to claim 29 wherein, the separator is a desalinator having a spiral cavity with, varied cross section along its length. 31 A desalinator according to claim 30 wherein, the spiral passage has a decreasing cross-section along its length.

3 A desalinator according to claim 31 wherein, the cross section of the spiral cavity decreases along its length from the at least one inlet.

33 A desalinator according to claim 32 wherein tfte decreasing cross section of the spiral passage produces a continuously increasing velocity of said feed solution as it travels along the spiral passage.

34 A desalinator according to claim 33 wherein a slit is provided upstream of first and second outlets, the first said outlet allowing the product solution of decreased concentration to exit the spiral and the second outlet allowing the exhaust waste solution of increased concentration to exit the spiral;

35 A desalinator according to claim 34 wherein the slit is adjustable to allow separate discharge from the spiral of the product solution of decreased concentration and the exhaust waste solution of increased concentration.

36 A method for desalination of salt water using an apparatus for separating a feed solution into a product solution of decreased concentration and an exhaust waste solution of increased concentration, the apparatus comprising:

b) a supply line for feeding said feed solution from me supply source to said apparatus;

c) means for driving said supply source into said apparatus under pressure;

the method comprising the steps of:

b) allowing the feed solution to travel through the spiral generating a centrifugal force sufficient to induce a separation in the feed solution;

c) causing the product solution of decreased concentration to exit the spiral via an outiet;

d) causing the exhaust waste solution of increased concentration to exit the spiral via another ou1 let

37 A method according to claim 36 comprising die further step of providing a slit upstream of said outlets and adjusting the slit to ensure to allow separate discharge from the spiral of the product solution of decreased concentration and the exhaust waste solution of increased concentration. 38 A method according to claim 37 wherein; the slit is adjustable to allow separate discharge from the spiral of the product solution of decreased concentration and the exhaust waste solution of increased concentration irrespective of the v ocity of the feed solution through said spiral..