GB2456153A

GB2456153A - Desalination method

Info

Publication number: GB2456153A
Application number: GB0800102A
Authority: GB
Inventors: Ian Stephen Bell
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-04
Filing date: 2008-01-04
Publication date: 2009-07-08
Also published as: GB0800102D0

Abstract

The present invention relates to a method and apparatus of producing water from a saline solution ie desalination of salt water to produce pure water. The method comprises the steps of: 1) rotating the saline solution 210 in order to create a surface on the saline solution due to centrifugal forces acting on the saline solution; 2) slidingly engaging a frictional element, such as a jet of air, with the surface 322 in order to generate heat within the surface due to the friction between the frictional element and the surface, to cause water to vapourise from the surface of the saline solution; 3) moving the vapourised water away from the surface; and 4) condensing the vapourised water into a liquid. The frictional forces are claimed to be generated by either air or a skid biased into engagement with the surface of the water. The evaporator further comprises a nozzle arranged to propel air at the surface of the liquid and a gas outlet arranged to remove the air with the entrained vapour. The nozzle pipe and the outlet pipe are arranged opposite one another. The air may additionally carry plastic granules which are entrained in the gas in order to increase the claimed frictional effects. Centrifugal forces acting upon the saline solution provides a surface which is sufficiently stable to enable the frictional element to rub up against and frictionally work upon the surface to generate the heat required without the surface disintegrating.

Description

A Method of Desalination and an Apparatus which implements the Method.

The present invention relates to a method and mechanism for producing water from a saline solution which is substantially free from saline, and more in particular, for producing drinkable water from sea water.

The surface of the earth generally comprises two components, namely land and sea.

Approximately 30% of the earth's surface is covered by land. Large areas of this land are capable of supporting vegetation. This due to the availability of reasonably pure water in these areas which is typically provided in the form of rain which falls onto the land. The fresh water in these areas also provides drinking water for animals and humans. However, other areas of land are devoid of such pure water and as such, are substantially devoid of vegetation or animals. These areas of land are typically uninhabited by humans due to the lack of water.

However, if reasonably pure water could be provided, much of this land could support vegetation andlor animals and therefore is more likely to be inhabited by humans.

The remaining 70% is covered by water. The majority of this water is located in oceans and seas which surround the land. The water contained within the oceans and seas contains salt, typically, sodium chlonde, dissolved within it, and is usually referred to as sea water. As such, this water is neither drinkable by most animals nor capable of supporting a large range of vegetation.

Large areas of the uninhabitable land is located near oceans and seas. Therefore, if the sea water in the adjacent oceans and seas could be processed in some manner to remove the salt content, reasonably pure water could be produced which could be used make the uninhabitable land habitable.

A number of solutions have been proposed by which reasonably pure water can be generated from sea water. However, the present invention is intended to provide an alternative method and apparatus to those already known.

Figure 1 shows a vertical cross section of an open beaker 100 containing a hot liquid 102. It is known that a beaker 100 of hot liquid 102, such as a cup of tea, cools down by emitting heat through the walls of the beaker 100. The cooling process is also aided by the evaporation 104 of the liquid 102, the water vapour 104 emanating from the surface 106 of the liquid 102. The rate at which the liquid 102 can be cooled can be increased by blowing air 108 across its surface 106 as shown in Figure 1. Air adjacent the surface becomes saturated with water vapour. By blowing air across the surface, it causes the existing water vapourlO4 adjacent the surface 106 to be moved away from the surface 106 to allow more water vapour to be generated. As such, the rate of evaporation is increased. As such, the rate at which vapourised water 104 is produced is dependent on the jet of air across the surface 106.

If the hot liquid 102 is a saline solution, the evaporation of water from the surface 106 provides a mechanism by which pure water can be obtained from the saline solution 102, the pure water being produced by the condensing of the water vapour 104. By blowing air 108 across the surface of the hot saline solution 102, the amount of water vapour 104 generated can be increased as the rate of evaporation is increased. As such, this provides a method of increasing the rate at which pure water can be obtained from the saline solution 102.

However, a problem with this method is that the rate at which vapour is produced is both a function of the temperature of the saline solution and the speed that the air is blown across the surface to aid evaporation.

Only a reasonable amount of vapour 104 is generated when the saline solution 102 is hot. This requires the whole of the saline solution 102 to be heated which requires a large amount of energy. If the saline solution 102 was at room temperature, though it would require no heating energy, only small amounts vapour 104 would be produced by evaporation. The ideal temperature of the saline solution 102 for evaporation is boiling point. However, at this temperature, the surface 106 of the solution 102 begins to disintegrate due to the water vapour 104 which would now be generated within the body of the saline solution 102, as well as at the surface 106, breaking through the surface 106 to enter into the air above it. As such, care has to be taken to ensure that boiling saline solution does not mix with the vapour.

The amount of vapour produced can be increased by increasing the speed of the air 108 blown across the surface 106. However, if the speed is too great, the surface 106 of the saline solution 102 disintegrates, potentially causing saline solution 102 to be blown out of the beaker 100 and mix with the vapour 104. As such, increasing the speed can only have a limited effect.

Once the surface 106 of the saline solution 102 begins to disintegrate (whether due to the saline solution 102 boiling or to excess speed of the air 108 blown across the surface 106), blowing air or increasing the speed of air 108 across the surface 106 will have a very limited effect on the amount of extra water vapour 104 produced whilst substantially increasing the amount of saline solution 102 splashed or sprayed from the surface 106.

However, it should be noted that the evaporation is not caused by heat energy generated by the frictional interaction between the air 108 and the surface 106 of the liquid as the strength of the air movement required for such heat generation would cause the surface 106 to completely disintegrate.

GB330805 discloses a centrifugal apparatus for effecting physical change. GB330805 discloses an improved evaporation apparatus over where the liquid to be treated is spread over a revolving cylinder by centrifugal force as a thin film while gases or vapours are caused to travel in intimate contact with the liquid under treatment. It does disclose the use of heat energy generated by the frictional interaction between the air and the surface the liquid to vapounse water in the saline solution.

US33090 16 discloses a system for separating water from salt water using centrifugal forces only. The saline solution is rotated at high speed. Fresh water weighs slightly less than salt water. As such, the fresh water rises to the surface of the rotating solution, the heavier salt solution migrating to the outer parts of the rotating solution due to the centrifugal forces action on it. This results in a concentrated saline solution away from the surface with substantially fresh water near the surface. These two layers can then be separated. A problem with this system is that the amount of force requiring to be applied to the saline solution is the order of 20,000G to 50,0000. This requires the saline solution to be rotated at extremely high speeds.

The use of friction to heat an object is known. Such use can be a benefit, for example, friction can be used in welding to generate the heat required to melt the material to be welded.

The molten material is then allowed to solidify to form the weld. Such use can be a problem.

When a space vehicle re-enters the earths atmosphere, its interaction with the atmosphere causes the outside of the space vehicle to heat up. This has resulted in the space shuttle, for example, having to be coated with specially formed tiles. However, the use of friction to heat the surface of a liquid is not known.

According to one aspect of the present invention, there is provided a method for producing water from a saline solution comprising the steps of: 1) rotatIng the saline solution in order to create a surface on the saline solution due to centrifugal forces acting on the saline solution; 2) slidingly engaging a frictional element with the surface in order to generate heat within the surface due to the friction between the frictional element and the surface to cause water to vapourise from the surface of the saline solution; 3) moving the vapourised water away from the surface; and 4) condensing the vapourised water into a liquid.

According to a second aspect of the present invention, there is provided an apparatus for producing water from a saline solution comprising: I) a vapourising unit which comprises: a rotatable housing which, when rotated, is capable of rotating a saline solution to hold it within the housing using centrifugal forces in order to produce a surface on the saline solution; a frictional element which is capable of slidingly engaging with the surface created on a saline solution when held by centrifugal forces within the rotatable housing, in order to generate heat within the surface, due to the friction between the frictional element and the surface, to cause water to vapourise from the surface of the saline solution; 2) a condensing unit to condense the vapourised water into a liquid; and 3) a conduction mechanism to move the vapourised water away from the surface of the saline solution to the condensing unit.

The key to the present invention is the unique way in which the water is evaporated from the saline solution. The surface of the saline solution is heated using the friction between the surface and the frictional element, when the frictional element is in sliding engagement with the surface. The centrifugal force acting upon the saline solution provides a surface which is sufficiently stable to enable the frictional element to rub up against and frictionally work upon the surface to generate the heat required without the surface disintegrating.

The frictional element may be a gas, such as air, or a solid, such as a mechanical skid.

However, it will be appreciated that it could be in the form of a liquid frictional element.

Furthermore, the frictional element can be any combination of a gas, a solid or a liquid.

Unlike the prior art examples, in the present invention, heat energy is not simply transferred from the frictional element to the liquid resulting in a temperature difference.

Instead, there is a frictional engagement between the surface of the saline solution and the frictional element to generate heat to vapounse the water, resulting in both getting hot.

A benefit of the present invention is that the interaction of the friction element and the solution is limited to the surface of the saline solution. The majority of the saline solution remains unaffected, other than having to be rotated. As such, it does not matter about the amount of saline solution needing to be rotated at any time nor is there a requirement to heat all or a large portion of the saline solution.

Another benefit of the present invention is that the water is vapounsed using a purely mechanical interaction. No separate heat source is required.

Energy is required to rotationally accelerate the saline solution to the correct speed. Not all of this energy however is lost as it is merely stored in the form of angular momentum.

Once the liquid is accelerated to the correct speed, the amount of energy required to maintain the speed is relatively small (dependent on the frictional losses).

A further benefit is that the salts within the saline solution would gravitate away from the surface due to being heavier than pure water. The surface would therefore have a reduced salinity, the reduction increasing as the centrifugal forces acting on the solution increases. If sufficient force is applied to the solution, the surface would be free from salt and therefore the frictional element would only interact with fresh water.

Whilst it is intended that invention should be implement using a frictional element and saline solution at ambient temperatures, it nevertheless still would operate with either either or both having a raised or reduced temperature.

Four embodiments of the invention will now be described with reference to accompanying drawings of which: Figure 1 shows a vertical cross section of an open beaker with a saline solution and which

forms prior art;

Figure 2 shows a perspective view of the desalination apparatus according to the first embodiment of the present invention; Figure 3 shows a vertical cross section of the air pump of the first embodiment of the invention; Figure 4 shows a lengthways vertical cross section of the vapourising unit; Figure 5 shows a cross sectional view of the vapourising unit in the direction of Arrows P in Figure 4; Figure 6 shows a cross sectional view of the vapounsing unit in the direction of Arrows N in Figure 4; Figure 7 shows a close up of the ends of the air inlet pipe and air outlet pipe; Figure 8 shows a vertical cross section of the condensing unit; Figure 9 shows a vertical cross section of the air pump of the second embodiment of the present invention; Figure 10 shows a close up of the ends of the air inlet pipe and air outlet pipe of the second embodiment of the present invention; Figure 11 shows a perspective view of the desalination apparatus according to the third embodiment of the present invention; Figure 12 shows a lengthways vertical cross section of the vapourising unit of the third embodiment of the present invention; Figure 13 shows a vertical cross section of the vapounsing unit in the direction of Arrows G in Figure 12; Figure 14 shows a cut away view of the barrel of the vapourising unit according to the first embodiment of the present invention; Figure 15 shows a sketch of a vertical cross section of a desalination apparatus according to the fourth embodiment of the invention with no saline solution within the barrel; Figure 16 shows a sketch of a vertical cross section of the desalination apparatus with saline solution within the barrel but with no air passing through the chamber; Figure 17 shows a sketch of a vertical cross section of the desalination mechanism with saline solution within the barrel and with air passing through the chamber; and Figure 18 shows a sketch of a vertical cross section of a part of the barrel 250 when rotated at different speeds.

Figures 2 to 8 and Figure 14 show the first embodiment of the present invention.

Referring to Figure 2, the desalination apparatus comprises a supply unit 200 which provides a supply of saline solution 210 which is to be desalinated, an air pump 202, a vapourising unit 204 and a condensing unit 206.

The supply unit 200 comprises a bucket 208 in which is located the saline solution 210. One end 212 of a hollow flexible pipe 214 connects to the base of the bucket 208 whilst the other end 216 connects to the vapourising unit 204. During the operation of the desalination apparatus, the saline solution 210 passes from the bucket 208 to the vapourising unit 204 through the pipe 214 under the effects of gravity due to the bucket 208 being located above the vapourising Unit 204. The rate of flow of the saline solution 210 into the vapourising unit 204 from the bucket 208 is controlled by the inner diameter of the pipe 214 and the height of the bucket 208 above the vapourising unit 204. It will be appreciated however that a control valve inserted into the hollow flexible pipe 214 could be utilised to control rate of flow of the saline solution 210. -The air pump 202 is connected to two flexible air pipes 218, 220. One end 222 of the first air pipe 218 connects to the air pump 202 whilst the other 224 end connects to the vapourising unit 204. One end 226 of the second air pipe 220 also connects to the air pump 202 whilst the other end 228 connects to the condensing unit 206. Dunng the operation of the desalination apparatus, the air pump 202 sucks air, through the second air pipe 220 from the condensing unit 206, into the air pump 202. The air pump 202 then blows the air at high speed and under great pressure through the first air pipe 218 from the air pump 202 to the vapourising unit 204.

Referring to Figure 3, the air pump 202 comprises a housing 236 connected to which at one end is an air inlet 230 and at the other end an air out let 232. The air inlet 230 is connected to the end 226 of the second air pipe 220; the air outlet 232 is connected to the end 222 of the first air pipe 218. An electric motor 234, having a drive spindle 238, is mounted via ribs 240 within housing 236. The longitudinal axis 242 of the spindle 238 extends towards the air inlet 230 and the air outlet 232. The electric motor 234 is connected to an electric power supply (not shown) using an electric cable 248 via an electric switch 246. The electric motor 234 can be switched on and off using the electric switch 246. Rigidly mounted on the spindle 238 of motor 234 is a fan 244.

When the motor 234 is activated using the electric switch 246, the spindle 238 rotates at high speed in the direction of Arrow Q. This results in the rapid rotation of the fan 244.

Rotation of the fan 244 draws in air from the air inlet 230 across the motor 234 and then blows it in the direction indicated by Arrows R through the air outlet 232.

It will be appreciated by the reader that there are numerous designs of air pump in the market and that any of these types of air pump can be utilised so long as they are capable of producing a jet of air which is of sufficient speed and pressure.

The air passing over the motor 234 aids in the cooling of the motor 234. This will inevitably result in an increase in the temperature of the air as it passes over the motor 234.

However, though the increase in the air temperature may be beneficial to the operation of this invention, it is not a requirement for its operation. Therefore, alternative designs of air pump where there is no increase in the temperature in the air as it passes through the pump can be used.

Refemng to Figure 2, 4, 5, 6 and 7, the vapourising unit 204 will now be described.

The vapoursing unit 204 comprises a barrel 250 rotatably mounted on a hollow rigid tubular pipe 252 via bearings 254 as best seen in Figure 4 which shows a lengthways vertical cross section of the vapourising unit 204. The barrel 250 has a uniform cross sectional shape along its length and which is of a circular tubular construction (as best seen in Figure 4). The barrel 250 has a longitudinal axis 258. The outer wall 256, which is of a uniform thickness, is located at a fixed radial distance from the longitudinal axis 258 of the barrel 250. Each end of the barrel 250 comprises a circular disk 260 which extends radially outwards from the longitudinal axis 258 to form an end wall. The outer periphery of the end walls connect to the end of the outer wall 256 in a sealed manner.

Each of the end walls 260 is mounted onto the hollow rigid tubular pipe 252 via the set of bearings 254 in order to enable the end walls 260, and thus the barrel 250 to freely rotate about the hollow rigid pipe 252. Each of the ends of the hollow rigid pipe 252 are fixed to a frame 262 in such a manner as to prevent any kind of movement.

A drive wheel 264 is rigidly connected to the one of the end walls 260 of the barrel 250, its axis being aligned with that of the longitudinal axis 258 of the barrel 250. Rotation of the drive wheel 264 results in rotation of the barrel 250. The drive wheel 264 connects to a rotary output drive 266 of a motor unit 268 via a drive belt 270. Rotation of the rotary output drive 266 results in rotation of the drive wheel 264. The motor unit 268 is rigidly connected to the frame 262 and comprises an electric motor (not shown) and a gear mechanism (not shown) connected between the motor and the rotary output drive 266 which increases the rotary speed of the output drive spindle of the motor to a suitable speed for the rotary output drive 266. The electric motor is powered from a mains power supply (not shown) and is activated using a switch 272.

A hole 274 is formed through one of the end walls 260 a predetermined radial distance from the outer periphery of the end wall 260.

Two apertures 276, 278 are formed through the side wall of the hollow rigid pipe 252 between the bearings 254 inside of the barrel 250.

S

A rigid water inlet pipe 280 passes through the first aperture 276 and extends radially away from the hollow rigid pipe 252 in an upward direction as shown in Figures 4 and 5.

Figure 5 shows a cross sectional view of the vapourising unit 204 in the direction of Arrows P in Figure 4. The rigid water inlet water pipe 280 is rigidly connected (not shown) to the hollow ngid pipe 252 at the point where it passes through the first aperture 276 so that it is prevented from moving. The hollow flexible pipe 214, which extends from the bucket 208, connects to the end of the rigid water inlet pipe 280 inside of the hollow rigid pipe 252. The other end 282 of the water inlet pipe 280 is curved so it points in a direction substantially parallel to the inner surface 284 of the Outer wall 256, in a tangential direction to the longitudinal axis 258.

A rigid air inlet pipe 286 and a rigid air outlet pipe 288 passes through the second aperture 278 and extend radially away from the hollow rigid pipe 252 in a generally upward direction as seen in Figures 4 and 6, at an acute angle relative to each other. Figure 6 shows a cross sectional view of the vapourising unit 204 in the direction of Arrows N in Figure 4.

Both air pipes 286, 288 are rigidly connected (not shown) to the hollow ngid pipe 252 at the point where they pass through the second aperture 278 so that they are prevented from moving. The end 224 first air pipe 218, which extends from the air pump 202, connects to the end of the rigid air inlet pipe 286 inside of the hollow rigid pipe 252. The other end 283 of the air inlet pipe 286 is curved so it points in a direction substantially parallel to the inner surface 284 of the outer wall 256, in a tangential direction to the longitudinal axis 258. An end of a vapour carrying pipe 290, which extends from the vapourising unit 204 to the condensing unit 206, connects to the end of the rigid air outlet pipe 288 inside of the hollow rigid pipe 252.

The other end 294 of the air outlet pipe 288 is curved so it points in a direction substantially parallel to the inner surface 284 of the outer wall 256, in a tangential direction to the longitudinal axis 258. However, the ends 283, 294 of the air inlet 286 and air outlet 288 pipes are arranged so that they point in the opposite direction to each other in order to face each other as best seen in Figure 6. This enables air blown out of the orifice of the curved end 283 of the air inlet pipe 286 to be generally directed towards the orifice of the curved end 294 of the air outlet pipe 288. The shape of the orifice of the curved end 283 of the air inlet pipe 286 is such so as to produce a narrow jet of air 296. The shape of the orifice of the curved end 294 of the air outlet pipe 288 is funnel shaped so that it is easily able to receive the narrow Jet of air 96 from the curved end 283 of the air inlet pipe together with any water vapour contained within it. Figure 7 shows a close up of the ends of the air inlet pipe 286 and air outlet pipe 288.

A thin circular metal disk 291 is rigidly attached to the hollow rigid pipe 252, between the two apertures 276, 278, and extends radially outwardly from the hollow rigid pipe 252. The function of the metal disk is to minimise the effect of the operation of the rigid water inlet pipe 280 on the operation of the rigid air inlet and outlet pipes 286, 288.

The condensing unit 206 will now be described with reference to Figure 8 and comprises a large container 300 having a lid 302 connected to the top of the container 300.

An end 304 of the vapour carrying pipe 290 passes through the lid 302 into the container 300.

The orifice of the end 304 of the vapour carrying pipe 290 points generally downwardly.

The end 228 of the second air pipe 220 which connects to the air pump 202 also extends through the lid 302 into the container 300. The end 228 is located away from the end 304 of the vapour carrying pipe 290 within the container and is separated using a gauze 306.

When the air pump 202 is operated, it sucks air out of the container 300, lowering the pressure within the container 300. This in turn causes air, together with any water vapour, to be sucked into the container 300 through the vapour carrying pipe 290 from the vapourising unit 204. The ends 228; 304 of the two pipes 220; 290 are separated both physically and by the gauze 306 to ensure that none of the air drawn through the vapour carrying pipe 290 is immediately drawn into the second air pipe 220 before it has had chance to deposit any water vapour contained within the air within the container 300. A small hole (not shown) is formed in the lid 302 of the container to prevent excessive pressure changes within the container 300.

The operation of the desalination apparatus will now be described.

The barrel 250 is rotatably driven at high speed by the motor unit 268 via the drive belt 270. The direction of rotation of the barrel 250 is indicated by Arrow M as can be seen in Figure 6.

The saline solution 210 is allowed to flow through the hollow flexible pipe 214 from the bucket 208 into the rotating barrel 250 via the inside the hollow rigid pipe 252, the hollow flexible pipe 214 passing through the bearings 254 as it does so. The saline solution passes from the flexible pipe 214 into and through the rigid water inlet pipe 280 and enters the barrel 250 close to the outer edge of the barrel 250 as best seen in Figure 5.

The rotation of the barrel 250 causes the saline solution 210 to rotate with the barrel 250, their rate of rotation being equal. Vanes (not shown) or similar such devices can be added to the inside of the barrel 250 to ensure that the saline solution 210 rotates with the barrel 250. As the saline solution 210 is rotating, the saline solution 210 locates to the radially outer edge of the inside of the barrel 250 due to centrifugal forces acting upon it, as shown in Figures 4, 5 and 6.

The depth 320 of the saline solution 210 within the barrel increases as more saline solution 210 enters the barrel 210 until the surface 322 of the saline solution reaches the hole 274 formed in the end wall 260 of the barrel 250. As the saline solution 210 continues to enter into the barrel 250, excess saline 210 solution will exit through the hole 274 under centrifugal force. As such, the depth 320 of the saline solution 210 remains constant with the position of its surface 322 remaining stationary relative to the inner surface 284 of the outer wall 256 of the barrel 250.

As the end 282 of the water inlet pipe 280 is curved, it directs the flow of the saline solution 210 in the same direction (Arrow M) of the rotation of the barrel 250 at an oblique angle to the surface 322 of the saline solution 210 already within the barrel 250. This minimises the amount of disturbance caused when the jet of saline solution 210 from the end 282 of the water inlet pipe 280 makes contact with the surface 322 of the saline solution 210 already located within the barrel 250.

The air pump 202 is activated using the electric switch 246. This causes the air pump 202 to drive air at high pressure and at great speed through the first air pipe 218. The air enters the rotating barrel 250 through the first air pipe 214 via the inside of the hollow rigid pipe 252, the first air pipe passing through the bearings 254 as it does so. The air passes from the first air pipe 218 into and through the rigid air inlet pipe 286 and enters the inside of the barrel 250 close to the surface 322 of the saline solution 210 as best seen in Figures 6 and 7.

The end 283 of the first inlet air pipe 286 is constructed to produce a narrow jet of air 296. The direction of the jet of air 296 is controlled by the curvature of the end 283 of the first air inlet pipe 286 so that it is directed towards the surface 322 of the saline solution 210 at an acute angle. The jet of air 296 engages with the surface 322 of the saline solution 210 and then is deflected away from it. The air outlet pipe 288 is positioned such that the deflected jet of air 296 enters into the orifice of the air outlet pipe 288, this entry being made easier by the fact that the end 294 of the air outlet pipe 288 is funnel shaped.

The jet of air 296 engages the surface 322 of the saline solution 210 along a circular path 324 which surrounds the axis of rotation 326 of the barrel 250. As the path 324 is circular, it is continuous, as best seen in Figure 14, which shows a cut away view of the barrel 250. The Continuous path 324 Is indicated by the track when visible in Figure 14 and by dashed lines when obscured by the outer wall 256 of the barrel 250. As such, the jet of air 296 engages with the same parts of the surface 322 on a repetitive basis.

As the jet of air 296 engages with the surface 322 of the saline solution 210, it frictionally rubs against the surface 322 generating heat within that part of the surface 322 due to the frictional interaction between the jet of air 296 and the surface 322. This heat causes the jet of air 296 and surface 322 of the saline solution 210 to increase in temperature. As the surface 322 heats up, the water within the saline solution 210, which forms the heated surface 322, or which is immediately adjacent to the heated surface 322, vapounses and enters the jet of air 296. The water vapour becomes entrained within the air flow and is removed away from the surface 322 by the moving jet of air 296. The air and entrained water vapour enter the air outlet pipe 288 due to movement of the jet of air. The air and entrained vapour is then drawn through the air outlet pipe 288, and then through the vapour carrying pipe 290 until it reaches the condensing unit 206 due to the suction force. The Suction force is caused by the air pump 202 drawing air out of the through the second air pipe 220, reducing the pressure within the condensing unit 206.

The salts within the saline solution 210 do not evaporate when the jet of air 296 frictionally engage with the surface 322 of the saline solution 210, but remains dissolved in the saline solution 210 in the barrel 250.

Once the air and entrained vapour enter into the condensing unit 206, they slow and cool down allowing the water vapour to condense into water 328. The end of the vapour carrying pipe 290 in the condensing unit 206 is located away from the end 228 of the second air pipe 220 and on the opposite side of a gauze 306. The gauze 306 inside the condensing unit 206 prevents the condensed water 328 from being sucked Out of the condensing unit 206.

If the water vapour within the entrained air condenses within the vapour carrying pipe 290, it will still be sucked into the condensing unit 206 due to the low pressure within the condensing unit 206 caused by the air pump 202 drawing air out of the condensing unit206.

The water 328 is substantially free form salt which remains dissolved in the saline solution 210 in the barrel 250.

As saline solution 210 is constantly being fed into the barrel 250 and any excess is constantly exiting the barrel 250 through the hole 274, the salinity of the saline solution 210 within the barrel 250 remains reasonably constant. This prevents the creation and build up of solid salts due to the increase in the salinity of the solution which would otherwise be caused by the evaporation process within the barrel 250.

The rate of rotation of the barrel 250 is such as to provide a surface 322 which remains relatively smooth and does not disintegrate when the jet of air 296 engages it.

It will be appreciated by the reader that the barrel 250 could be rotated using a hand crank and suitable gearing to generate the correct speeds. The dimensions of the barrel 250 can be reduced to enable a person to be able to rotate it manually.

Furthermore, it will be appreciated by the reader that the number of pairs of air inlet pipes 286 and out let pipes 288 can be used within a single barrel 250 as indicated by the dashed lines 330 in Figure 6. These can be located on the same path 324 on the surface 322 of the saline solution 210, as shown. Alternatively, they could be arranged so that they are on adjacent parallel paths.

Though the temperature of the air passing into the barrel 250 can be increased from that of the ambient temperature to improve the performance of the desalination apparatus, it will be appreciated that, in order to keep the construction simple and minimise the expenditure of energy, the air is forced into the vapourising unit 204 at the ambient air temperature. Similarly, the temperature of the saline solution 210 can be raised from that of the ambient temperature. However, in order to avoid any heating apparatus in the vapourising unit 204, it is left at the ambient temperature. However, if the temperature of the jet of air 296 and/or saline solution 210 were raised (so long as the saline solution 210 is not boiling as this would result in the break up of the surface 322 of the saline solution 210), water can still be vapourised from the surface of the saline solution 210 by frictionally engaging the surface 322 with the jet of air 296.

A second embodiment of the present invention will now be described with reference to Figures 9 and 10. The second embodiment is similar to that of the first embodiment. Where the same features are present in the second embodiment which are present in the first embodiment, the same reference numbers have been used.

The second embodiment is essentially the same as the first embodiment except for the addition of solid particles 350, such as plastic granules, to the air flow, the solid particles becoming entrained in the air flow and being blasted towards the surface 322 of the saline solution 210 with the jet of air 296. This increases the amount of heat generated when the jet of air 296 and entrained particles 350 frictionally contact the surface 322 of the saline solution 210 when compared to that when it is just the jet of air 296 alone.

Refernng to Figure 9, the air pump 202 used in the second embodiment is very similar to that used in the first embodiment. However, the air pump 202 in the second embodiment further comprises a funnel 352 attached to the side of the housing 236. The funnel 352 comprises a main chamber 354 in which is located plastic granules 350. The funnel 352 has a tubular passageway 356 which connects the main chamber 354 and the internal space 358 of the housing 236. The point where the tubular passageway meets with the space 358 within the housing 236 is down stream of the fan 244. The funnel 352 is located above the housing 236 so that the plastic granules 350 pass from the main chamber 354 of the funnel 352 through the passageway 356 and into the internal space 358 within the housing 236 due to gravity. The rate at which the plastic granules 350 enter the internal space 358 within the housing 236 is controlled by the diameter of the tubular passageway 356. However, it will be appreciated that a valve or metering device could be utilised to control the flow.

The rest of the desalination apparatus in the second embodiment is the same as that used in the first embodiment.

The operation of the second embodiment will now be descnbed. The second embodiment operates in the same manner as the first embodiment except for the addtrion of the plastic granules 350 into the air flow. When the pump is activated, the plastic granules 350 are allowed to fall into the internal space 358 within the housing 236 of the air pump 202.

The plastic granules 350 become entrained with the air which is being propelled by the rotating fan 244. The air and entrained granules travel at high speed and under pressure through the air outlet 232 and then through the first air pipe 218.

The air and entrained plastic granules 350 are propelled through the first air pipe 218 inside of the barrel 250 of the vapourising unit 204 (which is the same design as the first embodiment), then through the air inlet pipe 286, and then projected from the end 283 of the air inlet pipe in the form of a jet of air 296 with entrained plastic granules 350 towards the surface 322 of the saline solution 210. The jet of air 296 and plastic granules 350 impact on the surface 322 of the saline solution 210 and then deflect into the end 294 of the air outlet pipe 288. As the air 296 and granules 350 make contact with the surface 322, they frictionally rub against the surface 322 creating heat within the surface 322. The heat creates water vapour from the surface 322 of the saline solution 210 which is then entrained within the air and enters the end 294 of the air outlet pipe 288 with the jet of air 296 and plastic granules 350. The air, entrained plastic granules and water vapour then pass through the vapour carrying pipe 290 to the condensing unit 204 (which is the same design as the first embodiment), where the water vapour is condensed and resultant water 328 collected. The plastic granules 350 will be also caught within the condensing unit 206. These can then be filtered out of the condensed water 328.

The second embodiment descnbes the use of plastic granules 350. These are less dense than saline solution and as such would float on its surface if left within the barrel 250.

However, it will be appreciated that granules of material denser that the saline solution 210 may be used, such as sand.

A third embodiment of the present invention will now be described with reference to Figures 11 to 13. The third embodiment is similar to that of the first embodiment. Where the same features are present in the third embodiment are present in the first embodiment, the same reference numbers have been used.

In the third embodiment, instead of frictionally engaging the surface 322 of the saline solution 210 either with a jet of air 296, as described in the first embodiment, or with a jet of air 296 and plastic granules 350, as in the second embodiment, a skid 500 is used to frictionally engage with the surface 322 of the saline solution. The skid 500 is biased against and rubs along the rotating surface 322, the skid 500 frictionally engaging with the surface 322 to generate heat within the surface 322 to cause water in the surface 322 to vapourise.

Referring to Figure 11, the desalination apparatus is similar in design to that disclosed in the first embodiment. However, the first air pipe 218 has been removed. The rigid air inlet pipe 286 inside of the vapourising unit 204 has also been removed. In its place there is a rigid post 502 attached to the side of the hollow rigid tubular pipe 252 which projects radially from the side of the hollow rigid tubular pipe 252 towards the surface 322 of the saline solution.

Pivotally mounted onto the end of the post 502 is a skid 500. The skid comprises an engagement surface 504. The skid 500 is also connected to the post 502 via a spring 506 which biases the engagement surface 504 of the skid 500 away from the hollow tubular 252 pipe 252 towards the surface 322 of the saline solution 210.

In use, saline solution is provided in the barrel 250 in the same manner as the first embodiment of the present invention. The barrel 250 is rotated which in turn causes the saline solution 210 to rotate. The skid 500 is biased towards the saline solution by the spring 506 so that the engagement surface 504 slidingly engages with the surface 322 of the saline solution 210 along a continuous path 324 of the surface 322. The friction between the engaging surface 504 and the surface 322 of the saline solution 210 results in heat being generated in the surface 322 which in turn causes water in or the near to that part of the surface 322 to vapourise. The vapourised water is then sucked out of the barrel 250 through the air outlet pipe 288 and then through the vapour carrying pipe 290, into the condensing unit 206, by the low pressure in the condensing unit 204. The low pressure is caused by the air pump 202 drawing air out of the condensing unit 206 via the pipe 220.

The rate of rotation of the saline solution is such to prevent the spring 506 pushing the engaging surface 504 through the surface 322 of the saline solution 210. The strength of the spring 506 is chosen to maximise the frictional interaction between the engaging surface 504 and the surface 322 of the saline solution 210. Similarly, the physical characteristics of the engaging surface 504 are also chosen to maximise the frictional interaction between the engaging surface 504 and the surface 322 of the saline solution 210.

It will be appreciated that the engaging surface 504 of the skid 500 should slide in a consistent manner over the surface 322 of the saline solution 210, there being minimal pivoting movement of the skid 500 on the post 502. In order to achieve this, it may be desirable to also add a dampening mechanism to reduce any pivotal oscillation of the skid 500 on the post 502.

It will further be appreciated by the reader that a skid 500 as described in the third embodiment could be used in combination with a jet of air 296 as described in the first embodiment.

A fourth embodiment of the present invention will now be described with reference to Figures 15 to 18. The fourth embodiment is similar to that of the first embodiment. Where the same features are present in the fourth embodiment that are present in the first embodiment, the same reference numbers have been used.

Figure 15 shows the desalination mechanism according to the fourth embodiment of the present invention without any saline solution 210 located within it.

Referring to Figure 15, the desalination mechanism comprises an air pump 202, a vapourising unit 204 and a condensing unit 206.

The air pump is similar in construction to the air pump 202 in the first embodiment and as such, its design is self explanatory when seen in Figure 15. However, it will be appreciated that any suitable air pump could be used. Similarly, the condensing unit 206 is similar in construction to the condensing unit 206 in the first embodiment and as such its design is self explanatory when seen in Figure 15. However, it will be appreciated that any suitable condensing unit could be used.

The vapourisng unit 204 comprises a rotatable barrel 250. The front (forward end) of the vapourising unit 204 is on the right as shown in Figure 15. The barrel 250 is circular in cross section along its length. However, the diameter alters as shown in Figure 15.

The barrel 250 comprises a forward section 402 and a rear section 406. The barrel 250 is mounted on the air pump 202 via a first set of bearings 408 and is mounted on the condensing unit 206 via a second set of bearings 410. The barrel 250 can rotate about the longitudinal axis 414 of the vapourising unit 204 on the bearings 408; 410 but is prevented from sliding axially backwards and forwards. Seals (not shown) are provided adjacent the bearing 408; 410 so that air, water vapour and/or saline solution 210 can not leave the vapoursing unit 204 via the beanngs 408, 410.

The shape of the barrel 250 is such so as to produce of an annular trough 416, the opening of which faces radially inwards towards the longitudinal axis 414 of the vapourising unit 204. The barrel 250 is rotationally driven via a motor (not shown). When the vapourisng unit 204 is in use, the motor rotates the barrel 250 at predetermined rotational speeds which are capable of being adjusted to suite the particular situation.

Located within the barrel 250 symmetrically about the longitudinal axis 414 of the vapourising unit 204, is an air baffle 418 of circular cross section. The central part air baffle 418 is of a uniform size in cross section along the majority of its length. However, the ends 420, 424 of the air baffle 418 taper to a point as shown in Figure 15. The front end 420 (referred to as the nose) of the air baffle 418 projects into a space 422 surrounded by the front section 402 of the barrel 250. The rear end 424 (referred to as the tail) projects into a space 444 surrounded by the rear section 406 of the barrel 250. Struts 425 support the air baffle 418 and hold it stationary within the barrel 250.

A toroidal chamber 434 is formed by the inner wall 426 of the annular trough 416 and the central part (between the nose 420 and the tail 424) of the outer wall 428 of the air baffle 418. An entry funnel 430 is located forward of the nose 420 of the air baffle 418 which is attached to the inner wall of the housing 236 of the air pump 202. The air pump 202 drives air into the toroidal chamber 434 via the entry funnel 430.

Figure 16 shows the desalination mechanism with saline solution 210 located within it (but with no air passing through the mechanism).

Referring to Figure 16, in use, the barrel 250 is rotatingly driven by the motor. The saline solution 210 is fed into the annular trough 416 via a passageway (not shown) in the air pump 202 which passes through the space 431 surrounding the entry funnel 430. As the barrel 250 is rotating, it causes the saline solution 210 to rotate with it. As the saline solution 210 is rotating, it is forced radially outwardly, away from the longitudinal axis 414 of the barrel 250, against the base of the annular trough 416 due to centrifugal forces, as best seen in Figure 16.

A surface 322 is formed on the saline solution 210 which faces radially inwardly towards the longitudinal axis 414 of the barrel 250. A small gap 446 is formed between the surface 322 of the saline solution 210 and the air baffle 418. The gap 446 results in a passageway being created within the toroidal chamber 434 which allows air to pass through the barrel 250.

The mechanism by which saline solution 210 is fed into the annular trough 416 has not be shown as there are many ways by which saline solution can be fed into the annular trough 416 which will be readily appreciated by an engineer.

Furthermore, in addition to feeding saline solution into the trough 416, it is desirable to constantly remove saline solution 210 from the annular trough 416. If no saline solution is removed, there will be either an excess of saline solution 210 or a build of salts within the trough 416 as water is evaporated, which salts would require to be removed. By constantly removing saline solution, the salt is prevented from solidifying, thus ensunng that there is no build up of crystalised salts within the trough 416. A hole 433 is formed through the wall of the barrel 250 through which saline solution 210 can exit the barrel 250.

The speed of rotation of the barrel 250 together with the saline solution 210 can be made to be sufficiently fast that the effects of gravity on the position saline solution 210, and hence the position of the surface 322, within the annular trough 416, are negligent.

An exit vent 442 is formed behind the tail 424 of the air baffle through which a mixture of air and vapourised water generated from the saline solution 210 is able to exit the barrel 250 and enter the condensing unit 206.

When the barrel 250 is rotating with no air is passing through it, the surface 332 of the saline solution 210 remains substantially flat as shown in Figure 16. The gap 446 between the surface 332 of the saline solution 210 and the air baffle 418 remains relatively small.

However, when the air pump 202 is running, air is forced under pressure, to enter the barrel 250 through the entry funnel 430. Figure 17 shows the barrel 250 with saline solution 210 located within it and with air (Arrows K) passing through the barrel 250.

The airflow (which is equivalent to the jet of air 296 in the first embodiment), indicated by the Arrows K in Figure 17, engages with the nose 420 of the air baffle 418 where is directed radially outwardly as it passes into the chamber 434 formed by the barrel 250 and the air baffle 418. At this point, the air passes through the chamber 434 by passing through the passageway formed by the gap 446 between the surface 322 of the saline solution 210 and the air baffle 418 and then exits through the exit vent 442 into the condensing unit 406.

As the air passes through the passageway formed by the gap 446, it is further compressed due to the restriction caused by the narrowness of the gap 446. The amount of frictional contact between the air and the surface 322 of the saline solution is dependent on the amount of compression of the air. This can increase the pressure and temperature of the air as it passes through the passageway. The air flows across the surface 332 of the saline solution 210 in a direction substantially parallel to the surface 322 of the saline solution 210, and in frictional contact with the surface 322. Water vapour is generated by the heat caused by the friction between the surface 322 of the saline solution 210 and the air passing over the surface 322 of the saline solution 210, as the air passes through the gap 446. The water vapour emanates from the surface 322 and mixes with the air passing through the gap 446. The mixture of air and vapourised water then passes through the exit vent 442 into the condensing unit 406. The salt dissolved within the saline solution 210 remains within the saline solution 210 located within the annular trough 416.

Once the air and vapounsed water have exited the barrel 250 and entered the condensing unit 206, the water vapor is condensed.

The centrifugal forces acting on the rotating saline solution 210 will seek to keep the surface 322 of the saline solution 210 flat, as shown in Figure 16. However, due to the pressure of the air passing through the gap 446, the surface 322 will become displaced radially outwardly, as best shown in Figure 17, as the saline solution 210 is caused to move against the centrifugal force acting upon it. As such, the gap 446 widens. Figure 18 shows an enlarged view of the barrel 250 with saline solution 210 and with air passing through the gap 446. In order to reduce the width of the gap 446, the rate of rotation of the middle barrel 250 and saline solution 210 can be increased. This will increase the centrifugal forces acting on the saline solution 322 which will reduce the effects of the pressure of the air passing through the gap 446 on the surface 322, thus resulting in the surface 332 becoming flatter and the gap 446 becoming smaller, as indicated by the dashed line 448 in Figure 18.

Therefore, by controlling the rate of rotation of the barrel 250, and hence the saline solution 210, the size of the gap 446 can be controlled. By controlling the size of the gap 446, the temperature and pressure of the air passing through the gap 446 can be controlled. This will in turn control how much friction there is between the air and the surface 322 of the saline solution 210, thus the amount of heat generated, which in turn determines how much water vapour is created, which is then entrained within the air.

The size of the centrifugal forces acting on the saline solution 210 need to be kept at a level which prevents the saline solution 210 from simply being blown out of the chamber 434 and to maintain a surface 322 on the saline solution 210.

It will be appreciated that the size of the gap 446 can also be controlled in a second manner. The size of the gap 446 is also dependent on the amount of saline solution 210 located within the annular trough 416. By increasing or decreasing the volume of saline solution 210, the size of the gap 446 can be altered. This will provide further control in addition to the rate of rotation of the barrel 250.

It will also be appreciated that sufficient saline solution 210 could be introduced into the annular trough 416 so that there is no gap 446 until air commences passing through the barrel 250 in order to create a gap 446.

It will be further appreciated that a system for desalinating a saline solution can be constructed using a multiple of any of the four embodiments in succession, the condensed solution from one being fed into the next one, to improve the purity of the water subsequently produced.

Claims

Claims A method for producing water from a saline solution 210 comprising the steps of: 1) rotating the saline solution 210 in order to create a surface 322 on the saline solution 210 due to centrifugal forces acting on the saline solution 210; 2) slidingly engaging a frictional element 296; 504; 350 with the surface 322 in order to generate heat within the surface 322 due to the fnction between the frictional element 296; 504; 504 and the surface 322, to cause water to vapourise from the surface 322 of the saline solution 210; 3) moving the vapourised water away from the surface 322; and 4) condensing the vapourised water into a liquid.

2 A method as claimed in claim 1 wherein the frictional element 296; 504 slidingly engages the surface 322 along a continuous path 324.

3 A method as claimed in either of the previous claims wherein the saline solution 210 is rotated at such a rate that the surface 322 of the saline solution 210 is prevented from disintegrating as the frictional element slidingly engages the surface 322 of the saline solution 210.

4 A method as claimed in any one of the previous claims wherein the vapourised water is moved away from the surface 322 by being entrained within a flow of gas 296 which is then directed away from the surface 322.

A method as claimed in any one of the previous claims wherein the vapourised water is moved away from the surface 322 by being sucked or blown away from the surface 322.

6 A method as claimed in any one of the previous claims wherein all or part of the frictional element comprises a jet of gas 296.

7 A method as claimed in claim 6 wherein the gas is air.

8 A method as claimed in either of claims 6 or 7 wherein the jet of gas contains solid particles 350 entrained within it.

9 A method as claimed in any of claims 6, 7 or 8 wherein the direction of the jet of gas 296 is opposite to that of the direction of travel of the saline solution 210.

A method of desalination as claimed in any one of claims 6 to 9 wherein the jet of gas 296 shdingly engages the surface 322 of the rotating saline solution 210 in a direction substantially parallel to the surface 322.

11 A method as claimed in any one of claims 6 to 10 wherein the jet of gas 296 slidingly engages with the surface 322 at high speed.

12 A method of desalination as claimed in any one of claims 6 to 11 wherein jet of gas 296 is under high pressure as it slidingly engages with the surface 322.

13 A method as claimed in any one of claims 6 to 12 wherein the method further comprises the step of generating a restnctive passageway through which the jet of gas 296 passes, which is bounded at least in part by the surface 322 of the saline solution 210, the jet of gas 296 slidingly engaging with the surface 322 of the saline solution 210 when it passes through the restrictive passage way to cause water from the surface 322 of the saline solution to vaporize and mix with the jet of gas 296, the jet of gas 296 being compressed as it passes through the restrictive passageway, the compression being dependent on the dimensions of the restrictive passageway, the friction between the jet of gas 296 and the surface 322 being dependent on the amount of compression.

14 A method as claimed in claim 13 wherein at least part of the dimensions of the restrictive passageway is altered by the changing the shape and/or position of the surface 322 of the saline solution 210 within the passageway.

A method as claimed in claim 14 wherein the shape and/or position of the surface 322 is altered by altering the amount of centrifugal force acting on the saline solution 210.

16 A method as claimed in any one of the previous claims wherein the method further comprises the step of continuously removing and replenishing the saline solution 210 to prevent the generation of solid salts.

17 A method as claimed in any of the previous claims wherein all or part of the frictional element is part 504 of a mechanical skid 500.

18 A method as claimed in claim 17 wherein the skid 500 is biased towards the surface 322 of the saline solution 210.

19 An apparatus for producing water from a saline solution comprising: 1) a vapourising unit 204 which comprises: a rotable housing 250 which, when rotated, is capable of rotating a saline solution 210 to hold the saline solution 210 within the housing 250 using centnfugal forces in order to produce a surface 322 on the saline solution 210; a frictional element 296; 504; 350 which is capable of slidingly engaging with the surface 322 created on a saline solution 210 when held by centrifugal forces within the rotable housing 250, in order to generate heat within the surface 322, due to the friction between the frictional element 296; 350; 504 and the surface 322, to cause water to vapourise from the surface 322 of the saline solution 210; 2) a condensing unit 206 to condense the vapourised water into a liquid; and 3) a conduction mechanism 202 to move the vapourised water away from the surface 322 of the saline solution 210 to the condensing unit 206.

An apparatus as claimed in claim 19 wherein the frictional element 296;350;504 can be positioned relative to the surface 322 of the saline solution so that it slidingly engages the surface 322 along a continuous path 324 on the surface 322.

21 An apparatus as claimed in either of claims 19 or 20 wherein the housing 250 is capable of being rotated at a such a rate that the surface322 of a saline solution 210, when held in the rotating housing, is prevented from disintegrating as the frictional element 296; 350; 504 shdingly engages with the surface 322.

22 An apparatus as claimed in any of claims 19 to 21 wherein the conduction mechanism comprises a gas pump 202 to generate a gas flow which is used to move the vapourised water away from the surface 322 to the condensing unit 206.

23 An apparatus as claimed in claim 22 wherein the vapourised water is moved away from the surface 322 by being entrained within the flow of gas generated by the gas pump 202 which flow is then directed away from the surface 322 24 An apparatus as claimed in any one claims 19 to 23 wherein the conduction mechanism comprises a gas pump 202 to blow and/or suck the vapourised water away from the surface 322.

An apparatus as claimed in any one of claims 19 to 24 wherein all or part of the frictional element comprises a jet of gas 296 generated by a gas pump 202.

26 An apparatus as claimed in claim 25 wherein the gas is air.

27 An apparatus as claimed in either of claims 25 or 26 wherein there is provided a supply mechanism 352 which is capable supplying solid particles 350 to the jet of gas 296, part or all of the frictional element comprising the jet of gas 296 with entrained solid particles 350.

28 An apparatus wherein the same gas pump as claimed in claims 22 to 24 also generates the jet of gas 296 which as acts a frictional element as claimed in claims 25 or 26.

29 An apparatus as claimed in any one of claims 25 to 28 wherein the vapourising unit comprises a directing mechanism 283 which directs the jet of gas 296 in a direction opposite to that of the direction of travel of the saline solution 210 when held in the rotating housing 250.

An apparatus as claimed in any one of claims 25 to 29 wherein the jet of gas 296 slidingly engages the surface 322 of the rotating saline solution 210 in a direction substantially parallel to the surface 322.

31 An apparatus as claimed in any one of claims 25 to 30 wherein the jet of gas 296 is moved at high speed relative to the surface 322.

32 An apparatus as claimed in any one of claims 25 to 31 wherein the jet of gas 296 is under high pressure as it slidingly engages with the surface 322.

36 An apparatus as claimed in any one of claims 25 to 35 wherein the housing 250 comprises at least one wall 428 which is arranged so that it forms a restrictive passageway with a saline solution 210, when held by the housing 250, which passageway is bounded at least in part by the surface 322 of the saline solution 210, through which the jet of gas 296 passes, the jet of gas 296 slidingly engaging with the surface 322 of the saline solution 210 when it passes through the restrictive passage way to cause water from the surface 322 of the saline solution 210 to vaporize and mix with the jet of gas 296, the jet of gas 296 being compressed as it passes through the restrictive passageway, the compression being dependent on the dimensions of the restrictive passageway, the friction between the jet of gas 296 and the surface 322 being dependent on the amount of compression.

37 An apparatus as claimed in claim 36 wherein at least part of the dimensions of the restrictive passageway can be altered by changing the shape and/or position of the surface 322 of the saline solution 210 within the passageway.

38 An apparatus as claimed in claim 37 wherein the shape and/or position of the surface 322 of a saline solution, when held in the housing, is altered by altering the amount of centrifugal force acting on the saline solution 210.

39 An apparatus as claimed in any one of claims 19 to 38 wherein all or part of the frictional element is a part 504 of a mechanical skid 500.

An apparatus claimed in claim 39 wherein the skid 500 is biased towards the surface 322 of the saline solution 210.

41 An apparatus as claimed in any one of claims 19 to 40 wherein there is provided a saline solution supply system 200 and saline solution disposal system 274 which continuously remove and replenish the saline solution 210 in the housing 250 to prevent the generation of solid salts.

42 An apparatus which utilises, at least in part, any of the methods as claimed in any one of claims ito 18.

43 An desalination system comprising at least two of any of the apparatuses as claimed in any one of claims 19 to 41 arranged sequentially, wherein the out put of one mechanism is fed into the input of the next, and/or in parallel.