In the prior art there is known a water purification arrangement from the British patent publication GB-894936. Said arrangement includes two chambers, between which a closed air circuit is realized by means of a fan. In the first chamber, air is humidified by raw water, such as sea water, and in the second chamber the air humidity is condensed into pure water. The first chamber is provided with a spreader device. Raw water is sprayed from the spreader device onto the heating pipes, the temperature of which is below the boiling point of water. The water is evaporated, and it is transported along the current of air to the second chamber, where the air humidity is in turn condensed back to water. The second chamber is provided with a second sprayer device, through which the already condensed water is sprayed into the chamber, on the cooling pipes located therein. The humidity of the current of air is condensed in the chamber, and it is collected from the chamber bottom.

A problem with the above described water purification arrangement is presented by heat losses. In principle, the inner surfaces of the walls of the first chamber have the same temperature as the surroundings of the chamber, in which case the water that was evaporated in the chamber is condensed when it meets the inner chamber wall.

This is the case at least when the temperature of the surroundings is relatively low, such as 10-20°C. In addition, the maintaining of the temperature on a suitable level in the first chamber requires a lot of energy. This type of water purification device functions inefficiently, if it functions at all. In cold environmental conditions, the operation of the purification device is doubtful.

Another problem with the above described water purification device is that raw water drops are not separated from the current of air between the first and second chamber. In order to ensure that the water to be condensed in the second chamber should be pure, raw water must not enter therein. When the sprayer device sprays raw water against the heating pipes in the first chamber, there also are created raw water drops, and part of them occurs in very small droplets, which proceed along with the current of air and get mixed in the pure water in the second chamber. As a

consequence, in practice the water purification device does not function as it is said to function: by means of it, sea water is not turned into fresh water, but into less salty water.

Yet another problem in the described water purification device is that the spreader device of the first chamber is rapidly blocked by water impurities and, in the case of sea water, by the salt contained therein. Known spreader devices generally comprise a sieve or screen with tiny perforations, through which the pressurized water is fed.

The tiny perforations in the sieve collect raw water impurities or salt, and do not let water through anymore. These kind of spreader devices should be cleaned very often, in case they are used in a water purification device for treating raw water.

This, however, is not functional. In practice said spreader devices cannot be used in water purification devices. Another alternative is that raw water is filtered by an effective filter before feeding it into the spreader device. A drawback of this arrangement is that the filter is an auxiliary device in the water purifying arrangement, and it also needs a lot of maintenance. In addition, the filter does not prevent the salt from sea water from entering the spreader device.

Yet another problem in the described water purification device is that raw water is heated in the first chamber by spraying it against heating pipes. Only by circulating raw water through the chamber, its temperature rises high enough in order to effectively evaporate the humidity into the air flowing through the chamber. A similar problem is also encountered in the second chamber, where the pure water in turn is cooled by spraying it against cooling pipes. The cooling of pure water takes place gradually, as it is circulated through the chamber. On the other hand, the humidity condensed from the air continuously emits heat to the second chamber, which means that the cooling may be even remarkably slowed down, which weakens the condensing process and further the whole output of the water purification device.

The object of the invention is to eliminate the drawbacks connected to known water purification methods and arrangements. Another object of the invention is to realize a novel method and arrangement for purifying water, said method and arrangement being suited in the treatment of many types of raw waters in various different usage environments.

Another object of the invention is to introduce a novel droplet separator for a water purification device. By means of the new droplet separator, tiny liquid droplets,

such as water droplets, can be effectively separated from a gas flow, such as an air flow.

Yet another object of the invention is to introduce a novel sprinkler device for a water purification device. By means of the new sprinkler device, the original liquid, such as water, can be made into a water jet that spreads in the surroundings in a fan- like shape and is at the same time effectively distributed in small droplets. A remarkable advantage of the sprinkler device is that the original liquid may contain various particles and even relatively large earth or mineral particles or other similar particles without blocking the device. Likewise, various different substances can be dissolved in the liquid without remarkably affecting the operation of the sprinkler device.

A method according to the invention for purifying water is characterized by what is set forth in claim 1. The dependent claims 2-8 illustrate preferred embodiments of the invention.

The method according to the invention for purifying water makes use of two chambers and a closed air circuit arranged therebetween, said method comprising the following steps: - a temperature difference is arranged between the chambers, so that the temperature in the first chamber is higher than the temperature in the second chamber, - raw water is sprayed in the first chamber, - a first air flow is brought in the first chamber and in contact with the sprayed raw water, - a humidified second air flow is conducted in the second chamber, and - at least part of the humidity of the second air flow is condensed in the second chamber and recovered as pure water, in which case the humidity content of the first air flow leaving the second chamber is reduced, - the first air flow is conducted from the second chamber to the first chamber, and - the above described steps are repeated.

In addition, according to the invention in the method: - raw water is heated outside the first chamber and sprayed essentially in small droplets into the first chamber, - the temperature difference between the chambers is maintained by thermally insulating at least one of the chambers, and - raw water drops are removed from the humidified second air flow before it enters the second chamber.

As for the advantages of the invention, the following can be maintained. By means of the method, there is realized a water purifying arrangement that is simple in structure and capable of automatically adjusting itself in balance, as long as there is a sufficient but relatively small temperature difference between the first and second chamber. The flow rate of the air flow circulating through the channels and chambers is set, for example according to measurements, at a suitable constant speed, whereafter there is little need to intervene in the process.

Raw water can be heated by various different methods, for instance by utilizing waste heat from other processes or by making use of solar energy. This is simple to realize, when the raw water is heated particularly outside the first chamber.

The temperature difference between the chambers is maintained, and at the same time thermal losses are minimized, by thermally insulating at least one of the chambers, preferably the first chamber. The advantage is that now the chamber temperature is raised near to the raw water temperature, and the humidity of the air flow passing through the first chamber is optimized. Without thermal insulation, thermal losses can be really large, and the output as pure water is not satisfactory. In case the temperature of the surroundings is relatively high, it is advantageous to thermally insulate also the second chamber or, as an alternative, only the second chamber. The aim is that the condensing of the water vapor brought into the second chamber by the air flow is enhanced by providing the second chamber with heat insulation, in which case the hot surroundings cannot raise the temperature in the second chamber. This kind of a situation can be encountered for instance near the equator and/or in hot desert areas. When at least one of the chambers is thermally insulated, a sufficient temperature difference between the chambers is maintained, irrespective of the temperature and/or temperature fluctuations of the surroundings.

It is important that raw water droplets are removed from the humidified second air flow before it enters the second chamber. Otherwise the obtained result is not necessarily pure water, but it may contain deposits of raw water.

In a preferred embodiment of the invention, raw water drops are removed from the humidified air flow in several functional steps before it arrives in the second chamber. One-step droplet removal is usually not enough for eliminating finely divided liquid mist, particularly water mist, but several successive droplet removal steps must be applied, which steps are preferably realized by means of several successive droplet separator units.

In a preferred embodiment of the invention for arranging the spraying of raw water in the first chamber, the raw water is first set in a rotary motion with respect to the axis, whereafter it is allowed to be discharged through an exhaust aperture parallel with the axis in a rotary and outwardly expanding, spiraling motion. Thus a water jet with tiny droplets is arranged to be discharged through the exhaust aperture, and the creation of said water jet is based on a centrifugal motion. Therefore the diameter of the exhaust aperture is not a critical factor for the creation of tiny droplets, but the aperture can be relatively large. In a preferred embodiment of the invention, the diameter of the exhaust aperture is arranged to be preferably within the range 10-30 mm. An advantage of this kind of a raw water spraying method is that generally the quality of the raw water does not cause problems in its application. The raw water may contain particles of various sizes, and the raw water can be salt water, such as sea water.

In a preferred embodiment of the invention, the spraying of the raw water is arranged to take place upwardly. An advantage of this arrangement is that the distribution of the jet in droplets is enhanced by gravity. Another advantage is that in that case the pressure of the raw water can in most cases be moderate and energy- efficient.

In a preferred embodiment of the invention, the first air flow is brought in the first chamber at the bottom part of said chamber, and the humidified second air flow is arranged to be exhausted through the top part of the first chamber. An advantage is that the air flow passes through water mist in the main proceeding direction of the water jet. In addition, the temperature in the top part of the chamber is higher than in the bottom part, in which case the humidity that is absorbed in the air flow cannot be condensed back into the raw water. This is a risk, in case the air flows in the opposite direction.

In an embodiment of the invention, the air flow is brought in the first chamber and in contact with the sprayed hot raw water in several successive steps. As an advantage, it can be ensured that the air flow entering from the first air duct is effectively heated and saturated by humidity in the first chamber.

In a preferred embodiment of the invention, the thermal losses of the humidified air flow are minimized by thermally insulating the passage of the air flow at least as far as the removal step of the raw water drops. As an advantage, the condensing of the humidity of the humidified second air flow already in the vicinity of the first chamber can be prevented, which means that the pure water output can be increased. Without thermal insulation, thermal losses can become really large, and consequently the humidity of the second air flow probably begins to be condensed, which is seen as a drop in the output.

An arrangement according to the invention for purifying water is characterized by what is set forth in claim 9. The dependent claims 10-29 describe preferred embodiments of the invention.

The arrangement according to the invention for purifying water comprises a first and second chamber, between which chambers there are arranged two air ducts and in one of the ducts a fan for providing for the circulation of air between the chambers, wherein a first air flow is conducted through the first air duct from the second chamber to the first chamber, and through the second air duct from the first chamber to the second chamber; between the chambers, there is arranged a temperature difference by heating means provided in connection with the first chamber and by cooling means provided in connection with the second chamber, so that the temperature of the first chamber is higher than the temperature of the second chamber; said first chamber is provided with raw water supply means for feeding raw water to the chamber for increasing the humidity of the first air flow fed therein, and the second chamber is provided with humidity condensing means for reducing the humidity of the second air flow fed therein and for producing purified water. According to the invention: - the heating means provided in connection with the first chamber are realized by means of a raw water heating device and a hot raw water sprinkler equipment, said sprinkler equipment being arranged to serve as raw water supply means, and said raw water heating device being located outside the first chamber, and the sprinkler equipment being located inside the chamber,

- at least one of the chambers is provided with heat insulation, and - the second air duct is provided with a droplet separator for separating and removing raw water drops from the second air flow.

As regards the advantages of an arrangement according to the invention, we refer to what was maintained above. Let it be briefly pointed out that the arrangement is simple in structure, secure in operation, insensitive to the fluctuations of raw water quality, independent of the temperature of the surroundings and self-adjusting, which means that it automatically searches an efficient functional balance, depending on the temperature difference between the chambers and the rate of the air flow.

An advantage of the invention is that the raw water heat sources can be easily chosen among the ones that are available.

Another advantage of the invention is that by means of thermal insulation, a relatively small but sufficient temperature difference can be maintained between the chambers, in order to make the air circulation absorb humidity in the first step and condense humidity in the second step.

An advantage of a preferred embodiment of the invention is that favorable conditions for the absorption of humidity in the air circulation can be maintained in the first chamber, because the chamber is thermally insulated.

An advantage of the invention is that by means of the droplet separator unit, tiny liquid droplets, particularly water droplets, are prevented from entering the second chamber, where they could pollute or in general spoil the pure water produced by the arrangement.

In a preferred embodiment of the invention, the droplet separator includes a number of successive droplet separator units. In the various embodiments of the invention, said units may include for example a droplet separator unit provided with a number of essentially vertical spiral channels, and/or a droplet separator unit comprising a rotary blade wheel rotating freely around its axis in the air flow, said blade wheel including a number of blades. The advantage of this embodiment of the invention is that by this method, droplet separation is made to function efficiently, and in practice the access of all small droplets in the second chamber is prevented.

In a preferred embodiment of the invention, the droplet separator includes at least two droplet separator units, the first droplet separator unit comprising a number of walls changing the direction of the air flow, and the second droplet separator unit comprising a number of essentially vertical spiral channels. The advantage in this kind of droplet separator is that there is utilized both the deviation of the direction of the straight air flow for driving the droplets against the walls, and centrifugal forces for making the droplets collide in the duct walls owing to said forces.

In a preferred embodiment of the invention, the raw water sprinkler equipment includes at least one first sprinkler device, comprising a tank space that is rotation symmetrical with respect to its lengthwise axis, narrowing from the first end towards the second end, said first end being provided with a tangentially oriented raw water feed aperture, and the second end being provided with an exhaust aperture arranged on the axis, through which exhaust aperture water is arranged to be discharged.

Thus, in the first sprinkler device, raw water is first set in a rotary motion with respect to the axis, and then it is allowed to be discharged through the exhaust aperture arranged on the axis, in a rotary, spiraling motion that is outwardly expanding. By means of the sprinkler device, there is realized a raw water spraying method that was introduced above and is described in claim 3. An advantage of this embodiment of the invention is that the diameter of the exhaust aperture is not a critical factor for the formation of tiny droplets. The exhaust aperture can be relatively large. In a preferred embodiment of the invention, the diameter of the exhaust aperture is preferably in the range 10-30 mm. An advantage of this kind of raw water spraying is that the raw water quality does generally not cause problems in the operation, as was already maintained above.

In a preferred embodiment of the invention, the raw water sprinkler equipment includes a number of sprinkler devices that are arranged in successive sub-chambers of the first chamber, said sub-chambers being mutually separated by walls, so that air can freely circulate past the wall edges and proceed through the first chamber.

Thus the air flow is brought in the first chamber and in contact with the sprayed hot raw water in several successive steps. The advantage of this embodiment is that the air flow passing through the first chamber is made to maximally absorb the humidity, i. e. there is achieved a relative humidity of nearly 100%. At the same time also the air flow temperature is raised so that it at least approaches the temperature of the hot raw water. It is pointed out that the air saturation humidity grows, the warmer the air is. Consequently, by means of these arrangements, the

water content of the air flow conducted from the first chamber to the second chamber is maximized.

In a preferred embodiment of the invention, the sprinkler device is arranged in the bottom part of the first chamber, so that the exhaust aperture is directed upwardly.

The advantage is that by this procedure, there is achieved a water jet film with tiny droplets that is well distributed in the first chamber.

In an embodiment of the invention, the outlet end of the first air duct is connected to the bottom part of the first chamber, and the inlet end of the second air duct is connected to the top part of the first chamber. This arrangement is particularly well suited to be used, when the sprinkler device is arranged in the bottom part of the first chamber, so that the exhaust aperture is directed upwardly. The advantage is that by this arrangement, the air flow is made to be exhausted through the hot end, i. e. the top part of the first chamber, in which case its humidity also is at its maximum value.

In a preferred embodiment of the invention, the cooling equipment provided in connection with the second chamber comprises a humidity condensing device that is arranged in the second chamber, and a cooling arrangement for cooling the condensing device.

Moreover, it is advantageous to realize the humidity condensing device so that it includes at least one second sprinkler device. The structure of the device can thus be similar to the structure of the above described first sprinkler device that is applied in the first chamber.

It also is advantageous that the cooling arrangement includes pure water recirculation means, by which pure water is fed to the second sprinkler device and recirculated via the chamber to the cooling device for maintaining the temperature of the pure water clearly lower than the temperature of the hot raw water.

An advantage of the above described embodiments is that the condensing device realized by means of sprinkler devices functions effectively; the pure water broken into tiny droplets, the temperature of which is clearly lower than the temperature of raw water, binds the humidity of the entering warm air flow. By means of the cooling device, the sprinkled pure water is particularly cooled directly, which enhances the keeping of the second chamber cool and the condensing of the humidity in the pure water.

In a preferred embodiment of the invention where the above described condensing means are applied, in connection with the second air duct there is provided a second droplet separator, which advantageously is realized of at least two droplet separator units. The advantage in this embodiment is that the aim is to recover all of the pure water. Another advantage is that the humidity content of the air flow leaving the second chamber is clearly reduced, and the air flow preferably contains neither remarkable quantities of humidity nor, owing to the droplet separator, tiny droplets of liquid, particularly water, which are returned to the second chamber to increase the output.

In a preferred embodiment of the invention, the second droplet separator includes a droplet separator unit provided with a number of essentially vertical spiral channels.

This droplet separator utilizes droplet separator units that are in structure similar to those arranged between the first and second chamber in the first droplet separator.

In a preferred embodiment of the invention, the fan is fitted in connection with the second air duct, and it is also arranged to serve as one of the droplet separator units.

In this case the fan is particularly a centrifugal fan. It is advantageous to combine two functions in one and the same device, as is the case in here.

According to a preferred embodiment of the invention, the droplet separator for separating liquid droplets from the gas flow includes at least one droplet separator unit comprising an essentially vertically rising, spiraling pipe, the inner space whereof forms a spiral channel. A gas flow, such as an air flow, containing liquid droplets, such as water droplets, is conducted into the separator unit through an inlet located at the bottom, and respectively out of the separator unit through an inlet located at the top. In a spiraling pipe, the air flow assumes a spiraling motion, so that the droplets are sprinkled against the outer pipe walls and trickle down and out of the air flow inlet aperture. An advantage of the droplet separator according to the invention is that it is simple in structure and effective in operation.

In a preferred embodiment of the invention, the pipe of the droplet separator unit is realized as a corrugated pipe. In that case also the inner surface of the pipe is corrugated and forms an uneven collision surface for the liquid droplets, which further enhances the capture of the liquid droplets.

According to a preferred embodiment of the invention, a sprinkler device for spraying liquid, such as water, particularly for spraying waste water and/or sea water, comprises a tank space that is rotation symmetrical with respect to its

lengthwise axis and narrowed from the first end towards the second end, said first end being provided with a tangentially oriented raw water feed aperture, and the second end being provided with an exhaust aperture arranged on the axis, through which exhaust aperture water is arranged to be discharged.

In a sprinkler device according to a preferred embodiment of the invention, liquid is first set in a rotary motion with respect to the axis, and then it is allowed to be discharged through the exhaust aperture arranged on the axis, in a rotary, spiraling motion that is outwardly expanding. Thus there is arranged a liquid jet with tiny droplets to be discharged through the exhaust aperture, the formation of which jet is based on the centrifugal motion. Therefore the diameter of the exhaust aperture is not a critical factor to the formation of tiny droplets, but the exhaust aperture can be relatively large. An advantage of this type of spraying of liquid, particularly water, is that the liquid quality does not generally cause problems in the application thereof. The liquid may contain particles of various sizes, as well as chemical liquid components, either one of which factors could fairly rapidly block a conventional sprinkler device.

In a preferred embodiment of the invention, the diameter of the exhaust aperture of the sprinkler device is preferably 10-30 mm. When the sprinkler device feed aperture is of the same order, it is obvious that at least particles with a diameter in the range of a few millimeters pass through the sprinkler device without disturbing its operation. Even if the ingredients contained in the liquid are precipitated and accumulated on the exhaust aperture edges, the aperture is not immediately blocked, but the flowing of the liquid through the aperture continues.

In a second preferred embodiment of the invention, the tank space is realized by a bottom element and a dome, where the bottom element constitutes a flat, cylindrical housing, in which the feed aperture and feed connection are tangentially fitted, and the dome forms the tank space proper, which dome is detachably connected, for example by threadings, to the bottom element. An advantage of this embodiment is that owing to its structure, the sprinkler device can be easily maintained and adjusted to the operating conditions. The dome provided with an exhaust aperture is detachable and can be replaced, depending on the usage application, by a dome with a suitable shape and an exhaust aperture with a suitable diameter.

In a third preferred embodiment of the invention, in the middle of the bottom element, there is a is rotation symmetrical conical projection, protruding towards the dome. The advantage of this application is that by means of the projection, there is

provided a clear annular proceeding route for the liquid immediately as it is fed in through the feed aperture of the sprinkler device. It is, however, pointed out that the projection is not necessary, and that for example when the liquid is water, it is conducted, owing to the tangential connection of the feed aperture, to an orbit around the axis, circulating the center axis and conforming to the inner wall of the tank space.

In a fourth preferred embodiment of the invention, the tank space of the sprinkler device is hemispherical in shape. In general, the shape of the tank space is, at least in the vicinity of the exhaust aperture, conical and narrowing from the tank space diameter. In cross-section, the tank space can be straight or curved, so that said lines are mutually approaching and thus meet the exhaust aperture. In practice, it has been found out that a hemisphere is a functional and production-technically profitable shape.

In a fifth preferred embodiment of the invention, the edge of the sprinkler device exhaust aperture is provided with a number of projections and/or recesses that are arranged in the opening direction of the aperture. As was already maintained above, the liquid is allowed to be discharged through an exhaust aperture arranged on the axis, in a spiraling and outwardly expanding motion. In some cases the liquid tends to be discharged in a thin, gauze-like film from the exhaust aperture. This can now be avoided by breaking the edge line of the exhaust aperture by suitable small projections or respective recesses. By this procedure it is ensured that the liquid jet discharged from the exhaust aperture has tiny droplets.

The invention and its further advantages are described in more detail below with reference to the appended drawings, where figure 1 is a schematical illustration of an arrangement according to the invention, figure 2 is a cross-sectional illustration of a droplet separator, figure 3A is a cross-sectional illustration of a droplet separator unit or a corresponding droplet separator, and figure 3B illustrates the cross-section of a second droplet separator unit or a corresponding droplet separator pipe, figure 4A is a cross-sectional illustration of a sprinkler device,

figure 4B is a top-view illustration of a sprinkler device, with the dome removed, and figure 4C is a top-view illustration of a sprinkler device, figure 5A is a cross-sectional illustration of the exhaust aperture of another sprinkler device, and figure 5B is a top-view illustration of said exhaust aperture, figure 6 is a schematical illustration of the droplet separator and fan provided in connection with the second air duct, and figure 7 is a schematical illustration of the sub-chambers of the first chamber, provided with sprinkler devices.

Like numbers for like parts are used in the drawings.

An arrangement for purifying water according to the invention is schematically illustrated in figure 1. There are shown the first and second chamber 1,2, between which there are arranged two air ducts, a first and second air duct 3,4 and a fan 5 for providing the circulation of air between the chambers. Through the first air duct 3, a first air flow Al is conducted from the second chamber 2 to the first chamber 1, and through the second air duct 4 from the first chamber 1 to the second chamber 2.

Between the chambers 1,2 there is arranged a temperature difference AT. By the heating means 18,6 provided in connection with the first chamber 1, the chamber temperature is set at the first temperature Tl. The cooling equipment 7,71 provided in connection with the second chamber is in turn used for setting its temperature at the second temperature T2, so that the temperature of the first chamber 1 is higher, T, > T2, than the temperature of the second chamber 2, and that the temperature difference therebetween is AT.

The first chamber 1 includes raw water supply means for feeding raw water RW to the chamber 1 in order to increase the humidity of the first air flow Al fed therein.

The second chamber 2 is provided with humidity condensing means for reducing the humidity of the second air flow A2 fed therein and for producing purified water W.

The heating means provided in connection with the first chamber 1 are realized by a raw water RW heating device 18 and hot raw water RW1 sprinkler equipment 6.

The sprinkler equipment 6 is arranged to serve as the supply means for raw water

RW. The raw water heating device 18 is located outside the first chamber 1, and the sprinkler equipment 6 is located inside the chamber.

At least one of the chambers 1, 2, in this embodiment the first chamber 1, is surrounded by heat insulation 16; 16a. Thus the thermal losses from the chamber 1 are minimized. As an alternative, the second chamber 2, or even both chambers 1, 2, can be provided with heat insulation, such as a heat insulation layer 16; 16b. The heat insulation layer 16; 16a, 16b is realized for example by polyurethane foam or the like. Thus the temperature difference between the chambers can be maintained on a desired level irrespective of the temperature and/or temperature fluctuations of the surroundings.

The second air duct 4 includes a droplet separator 8 for separating and removing raw water droplets from the second air flow A2.

The first chamber 1 includes a sprinkler equipment 6 serving as raw water supply means. Thereby hot raw water RW is fed in small droplets RW1 to the chamber 1 for humidifying the air flow passing therethrough. The sprinkler equipment 6 preferably includes a sprinkler device 60; 60a. The second chamber 2 is provided with air humidity condensing means, such as a condensing device 7. By means of said means 60,7, in the first step the temperature and humidity content of the air circulating between the chambers 1,2 is raised by the hot raw water RW; RW1 and the water vapor evaporated therefrom, and then in the second step the temperature and humidity are reduced in conditions that are cooler with respect to the raw water temperature, and turned back into water, particularly into pure water W1, by means of said condensing means.

The first chamber 1 of the purification chamber includes a first sprinkler device 60; 60a, by which raw water (temperature T, is about 60-80°C) is first sprayed, i. e. rendered in a relatively small droplet size. The dry and relatively cool air flow (temperature advantageously in the range 20-40°C) is conducted from the outlet end 3b of the first air duct 3 to said chamber 1, particularly to its bottom part la, through the sprinkled hot raw water RW1 and further out of the chamber, particularly through its top part lb, to the inlet end 4a of the second air duct 4. The air flow leaving the chamber 1 is remarkably warmer owing to the raw water temperature, and its relative humidity is increased (for roughly 70-90%).

Consequently, the first chamber 1 is the heating and humidifying chamber of the air flow. In the second air duct 4, the humid and warm air flow is first arranged to pass through the droplet separator 8, whereafter it is conducted to the second chamber 2.

The droplet separator 8 prevents the raw water drops from proceeding along with the air flow to the second chamber 2. In the second chamber 2, the humid and warm air flow coming from the outlet of the second air duct 4 is conducted to humidity condensing means, such as a condensing device 7, where the air flow is cooled off (to a temperature T2 that is roughly 20-40°C), and as a consequence, the water vapor contained therein is condensed into pure water Wl. Now the temperature difference AT = Tl-T2 between the chambers 1,2 is within the range 20-60°C.

Raw water RW is heated outside the chamber 1. Heating can be realized for instance in a separate raw water tank 14 or in a corresponding tank by means of a heating device, such as a heat exchanger 18, connected thereto, for example by utilizing the waste heat from a power plant, a power tool or the like, or for instance by utilizing solar energy. The required raw water RW temperature is roughly 50- 80°C, which means that many different kinds of heat sources can be utilized, depending on the size and capacity of the equipment. From the tank 14, the hot raw water RW is transferred, along the inlet pipe 14a, at a suitable pressure, for example by means of a pump 15, to a sprinkler device 60; 60a and to the chamber 1 in tiny raw water droplets RW1. The raw water collected at the bottom of the chamber 1 is conducted to the outlet pipe 14b and further back to the tank 14.

It is advantageous to arrange a continuous, replacing supply of raw water RW, or a periodic washing and simultaneous raw water addition to the tank 14. For this purpose, the tank 14 is provided with a supply and exhaust pipe 14c, 14d. In this way for example the accumulation of salt in the tank is prevented, when the employed raw water is sea water.

From the point of view of the operation of the water purification arrangement, it is important that at least one of the chambers 1,2, preferably the first chamber 1, is provided with heat insulation 16. Depending on the conditions, it can also be appropriate to provide both the tank 14 as well as the inlet and outlet pipes 14a, 14b with a suitable heat insulation 17.

The cooling equipment provided in connection with the second chamber 2 comprise a humidity condensing device 7 serving as the humidity condensing means and being arranged in the second chamber 2, and a cooling arrangement 71,90 for cooling the condensing device 7. The humidity condensing device 7 includes a second sprinkler device 60; 60b. The second sprinkler device 60b can be similar as the first sprinkler device 60, but it can also be realized by means of conventional nozzles, one or several, provided with small perforations. The cooling arrangement

90 includes pure water W recirculation means 72a, 72b, 73, whereby pure water W is fed n the second sprinkler device 60; 60b and recirculated via the chamber 2 to the cooling device 90 for maintaining the pure water temperature clearly lower in comparison with the hot raw water temperature.

The pure water recirculation means 71 include inlet and outlet pipes 72a, 72b, and a pump 73 in the inlet pipe 72a. The cooling device 90 is connected to the inlet and outlet pipes 72a, 72b outside the second chamber 2. The cooling device 90 is advantageously a heat exchanger that is immersed in a suitable cooling tank 72.

Through the inlet pipe 72a, by means of the pump 73, pure water W is fed from the cooling device 90 to the sprinkler device 60b, and then it is sprayed in tiny droplets Wl to the second chamber 2, whereafter the water is collected from the bottom of the chamber 2 to the outlet pipe 72b and fed to the cooling device 90. Pure water is transferred in the sprinkler device 60b, the recirculation means 71 and the cooling device 90, but the quantity is relatively small depending, however, on the size of the equipment. The cooling tank 72 is for example the sea, the temperature whereof can be for instance 25-30°C. Thus it is clearly lower than the temperature of the hot raw water RW1 in the chamber 1 and the temperature of the humid air flow entering the second chamber 2. When necessary, the cooling arrangement, particularly the recirculation means 71, can be thermally insulated, in case for example the temperature of the surroundings is relatively high or in case it at least temporarily rises relatively high.

As an alternative, the condensing device 7 can be realized by another known method, for example as a pipework that is arranged to pass through the second chamber 2, provided with suitable cooling, such as water or air cooling. An air flow is conducted through the pipework from the second air duct 3, so that the humidity is, owing to the low temperature, condensed in the pipework, from where is conducted out. It is pointed out that in the second chamber 2, there is treated pure water, which means that unlike in the first chamber 1, the corrosive factors of waste or salt water are not present. Therefore the treatment of the air flow, the humidity contained therein and the water is on the pure water side clearly simpler, and many different kinds of known condensing means can be utilized.

In the described embodiment, condensed pure excess water W2 is recovered for example from the bottom of the second chamber 2 by conducting it out through an overflow pipe 21. From the second chamber 2, the cooled air flow that has lost most of its humidity is conducted to the first air duct 3 and to a second droplet separator 9 arranged at the first end 3a thereof, and further via a fan 5, such as an axial and/or

centrifugal fan, to the first chamber 1. Thus the water purification arrangement has a closed air circuit, arranged to transfer humidity from the first chamber 1 and emit it in the second chamber 2.

In the described embodiment of the invention, figure 2a, the droplet separator 8 arranged in the second air duct 4 comprises a number of successive droplet separator units 81,82, 83. The droplet separator 8 includes is at least two droplet separator units, of which the first droplet separator unit 81 comprises a number of walls 81 a changing the direction of the air flow, and the second droplet separator unit 82 comprises a number of essentially vertical spiral channels 82a. As a complement for the droplet separator 8, and for securing the operation, even a third droplet separator unit 83 can be added, comprising a blade wheel rotating freely around its axis in the air flow, provided with a number of blades. The two first droplet separator units 81,82 are used for separating relatively large droplets from the air flow, and the latter droplet separator 83 utilizing centrifugal forces is used for eliminating droplet mist by driving it onto the separator walls, from where it trickles as liquid back to the first chamber or directly to a raw water store or the like.

The second droplet separator unit or a corresponding droplet separator 82 comprises one (cf. figure 3A) or advantageously a number (cf. figure 2) of essentially vertical spiral channels 82a, fitted in a suitable housing 820. Each droplet separator unit 82 is arranged so that its inlet aperture 821a is placed low and its outlet aperture 821b is placed high. When there are used several droplet separator units 82, they are arranged adjacently, as is illustrated in figure 2. The inlet apertures 821a are connected to the side of the first chamber 1 in a common inlet chamber 822a, and the outlet apertures are arranged in a common outlet chamber 822b. In the embodiment of figure 2, the inlet chamber 822a is connected to the outlet aperture of the first droplet separator unit 81, and respectively the outlet chamber 822b is connected to the inlet aperture of the third droplet separator unit 83.

The spiral channel 82a of the second droplet separator unit 82 or a corresponding droplet separator is realized of pipe 821 that is wound in a spiraling fashion around an elongate, straight center axis A-A, as can be seen especially in figure 3A. In an embodiment, the pipe 821 is realized of a straight and smooth pipe. The employed pipe material can be a suitable neutral and wear-resistant plastic, or as an alternative, for instance stainless steel, even.

In the second droplet separator unit 82, the centrifugal forces affect the air flow proceeding in the spiral channel 82a, and particularly the relatively heavy water droplets contained therein, in which case the droplets collide in the channel walls and trickle in the channel downwards to a suitable collection vessel, or along the pipe to a raw water store.

In a preferred embodiment of the second droplet separator unit 83 the spiral channel 82a is realized as corrugated pipe, as is illustrated in the cross-section shown in figure 3B. Now the inner pipe wall is provided with undulating bulges 823 and valleys 824 alternating in succession in the lengthwise direction of the pipe, said bulges and valleys enhancing the purification of the air flow, proceeding in a spiraling motion in the spiral channel 82a, of water droplets.

It is practical to provide the droplet separator 8 arranged in the second air duct 4 by heat insulation 84. Likewise, for avoiding thermal losses, it is recommendable to provide at least the outlet end 4a of the second air duct 4 between the first chamber 1 and the droplet separator 8 by heat insulation 85.

A preferred embodiment of the sprinkler device 60; 60a, 60b that is applied for spraying raw water at least in the first chamber 1 is illustrated in figures 4A, 4B, 4C, and another preferred embodiment is illustrated in figures 5A and 5B.

The sprinkler device 60 comprises a tank space 61, in connection with which there is provided a feed aperture 62 and an exhaust aperture 63. The tank space 61 is formed of a space that is narrowed from the first end 61a to the second end 61b and is rotation symmetrical in relation to the axis B-B. In the first end 61 a of the tank space 61, on the axis B-B, there is tangentially arranged a feed aperture 62 directed towards the tank space. In the second end 61b of the tank space 61, on the axis B-B, there is in turn centrally arranged an exhaust aperture 63, which is round.

In the sprinkler device 60, raw water is fed in through the feed aperture 62 (cf. the arrow) at a suitable pressure, and the water is respectively arranged to be discharged through the exhaust aperture 63. Owing to the tangential feed direction, the water obtains a rotary motion in the tank space and is forced, maintaining its motion, out through the exhaust aperture 63, breaking into small droplets in the process. An advantage of the sprinkler device is that the exhaust aperture 63 is relatively large, wherefore it is not easily blocked. Blocking is the danger with most sprinkler devices, because the raw water can be salt water, such as sea water, or some other

kind of polluted water not fit for household water, possibly containing various different pollution, earth or other particles of different sizes.

The diameter D of the exhaust aperture 63 of the sprinkler device 60 is preferably 10-30 mm. The diameter K of the sprinkler device 60 can be for example in the range 100-200 mm, and the height h for example 70-150 mm.

In a preferred embodiment of the sprinkler device 60, the tank space 61 is realized of a bottom element 65 and a dome 66. The bottom element 65 is a low and flat, cylindrical housing, in which the feed aperture 62 and the corresponding connection is tangentially fitted in the rotary object forming the bottom element in the axis B- B. At the same time, inside the housing of the bottom element 65, there is created a cylindrical space that is arranged to receive the water coming from the feed aperture 62, so that the water is set in a rotary motion. It is pointed out that any control blades or the like are not used, and owing to the nature of the raw water, they could not be used in any case. Inside it, the dome 66 forms the tank space 61 proper. The dome 66 is connected detachably, for instance by threadings, to the bottom element 65.

In the middle of the bottom element 65 of the sprinkler device 60, there is a rotation symmetrical conical projection 67 protruding towards the dome 66 and the exhaust aperture 63. Said projection is not, however, necessary for the operation of the sprinkler device. It is only used for ensuring that the incoming raw water starts to rotate irrespective of the impurities and particles contained therein, when the raw water is fed in through the feed aperture 62.

The tank space 61 and also the dome 66 of the sprinkler device 60 are hemispherical in shape. It has been empirically found as an advantageous tank shape. Also other geometrical shapes, such as a straight conical shape, or intermediate shapes between conical and spherical, are possible. The requirement is that the tank is narrowed towards the exhaust aperture, in which case also the speed of the water flow set in a rotary motion is increased.

The edge 63a of the exhaust aperture 63 of the sprinkler device 60 can be a straight edge parallel with the axis B-B. However, it is advantageous to bevel the edge 63a of the exhaust aperture, so that it is opened outwardly. By means of the spread angle a, the fan-like spreading of the water jet emitted from the exhaust aperture 63 can be at least somewhat adjusted in the desired way; the larger the spread angle a, the wider the fan of the water jet.

In a preferred embodiment, the edge 63a of the exhaust aperture 63 of the sprinkler device 60 is provided with a number of grooves 64 and/or recesses. These are arranged to proceed in the lengthwise direction of the aperture 63, i. e. in the opening direction, and they deviate from the direction of the axis B-B for the measure of the spread angle a, as can be seen in figure 5A. By means of the grooves 64 and/or corresponding recesses, the water discharged through the exhaust aperture 63 is disturbed by the shape of the edge 63a, so that the emitted film of water is broken and distributed in even tinier droplets. This is the primary purpose of the sprinkler device 60 when used in connection with a water purification device and particularly the chamber 1 according to the invention.

As was maintained above, in the description of the water purifying arrangement according to the invention, in an embodiment of the invention the air flow that has been cooled off in the second chamber 2 and lost most of its humidity is conducted to the first air duct 3 and to the second droplet separator 9 arranged in the first end thereof. Thus, in connection with the first air duct 3, there is provided a second droplet separator 9. This is advantageously arranged, in the proceeding direction of the air flow, before the fan 5. The second droplet separator is advantageously realized of at least two droplet separator units 91,92, as is illustrated in figure 6.

It is advantageous that the second droplet separator 9 has a droplet separator unit 91, provided with a number of essentially vertical spiral channels 91 a. Accordingly, this droplet separator unit 91 corresponds in structure to the second droplet separator unit 82 applied in connection with the first droplet separator 8 and described above.

All that was said referring to it, also applies to the droplet separator unit 91 of the first duct.

It also is advantageous that the fan 5 that is fitted in connection with the first air duct 3 also is arranged to serve as one of the droplet separator units 92 of the droplet separator 9.

In the second droplet separator 9, figure 6, the inlet chamber 911 of the first droplet separator 91 is connected to the outlet end 3a of the first air duct 3, which in turn is connected to the second chamber 2. The first droplet separator 91 includes a number of adjacent spiral channels 91a that lead from the inlet chamber 911 to the intermediate chamber 912. The spiral channels 91a are fitted in a suitable load- bearing housing 92. The intermediate chamber 912 is in turn connected to the suction side of the axial fan 5, so that air proceeds, urged by the blades of the blade wheel 94, further to the outlet chamber 913 and to the first duct 3, particularly to the

inlet end 3b thereof, leading to the first chamber 1. The pure water droplets are stopped in the first step on the walls of the spiral channels 9 la and in the second step, beaten by the blade wheel 94, against the duct wall surrounding the blade wheel. In both cases, pure water is preferably recovered by conducting it for instance back to the second chamber 2.

In a water purifying arrangement according to the invention, figure 7, the first chamber 1 is divided by walls into sub-chambers 11,12, 13, which are, however, mutually connected. The sub-chambers 11,12, 13 are separated by walls 111, 112, so that air can circulate past the edges of the walls and proceed through the first chamber 1 from the first air duct 3; 3b to the second air duct 4; 4a. The air ducts 3; 3b, 4; 4a are preferably connected to the opposite end walls of the chamber 1. Also in this embodiment, the chamber 1 is provided by heat insulation 16. The raw water sprinkler equipment 6 comprises a number of sprinkler devices 60; 601,602, 603.

They are arranged in the successive sub-chambers 11,12, 13 of the first chamber.

The sprinkler devices 60; 601,602, 603 are connected, via the pump, to the raw water tank in similar fashion as in the embodiment of figure 1. By this arrangement it is ensured that the air flow entering the first air duct 3; 3b is efficiently heated and saturated by humidity.

In a water purifying arrangement according to the invention, the second chamber 2 is divided by walls into sub-chambers, and can be provided with a number of sprinkler devices 60b. In that case the second chamber 2 would essentially correspond to the structure of the first chamber 1 illustrated in figure 7.

The invention is not restricted to the above described embodiments only, but many modifications are possible within the scope of the inventive idea defined in the appended claims.