TECHNICAL FIELD OF THE INVENTION

The invention relates to a water spray cooler and a method for cooling water according to the preambles of the independent claims presented below. The invention relates especially to a spray cooler to be located on the surface of the water.

PRIOR ART

Spray coolers are used for example for cooling industrial process waters and turbine waters of thermal power stations. A typical spray cooler located on the surface of the water comprises a frame and supported thereon a pump, a water guiding device and a power source, such as an electric motor. With the pump, water is brought to flow upwards towards the water turning device, such as a baffle, located above the surface of the water, through which device the water is sprayed back on the surface of the surrounding water. Generally, the spray cooler comprises floats for keeping it on the surface of the water.

Cooling of water is based on its evaporation during its flight in the air. Significant facts for the efficiency of the spray cooler are for example the size and the amount of the drops to be formed, the distance and velocity of the drops travelling in the air, the amount of water to be transferred and the amount of air, which is brought into contact with water. For example patent publication EP 2266683 A2 discloses a spray cooler, in which a propeller pump lifts water upwards in a pipe from below the surface of the water above the surface. After the upper end of the pipe, the water hits the lower surface of a horizontal and round and horizontally rotatable baffle, to which have been fastened blades in direction of the baffle radius. The baffle and the blades spray the water back on the surface of the water. Publication GB 1506548 discloses a cooler, in which water sprays diagonally upwards from a narrow slot. Small drops will not come out of the slot, so the coefficient of efficiency of the cooling remains low. A cooling fan is needed for intensifying the air flow.

The coefficient of efficiency of prior art solutions could be better, for example, all water to be pumped does not hit the baffle or the blades, the form, the direction and the size of the water spray are not optimal, and the water does not drop into drops having a suitable size. Many solutions have an insufficient air flow.

In a spray cooler, a very significant fact in improving the efficiency is that as large amount of dry air as possible can be moistened in the water spray. Air is typically moved several cubic meters per second, for example over 4 m ³ or over 6 m ³ per second. A surface aerator, which externally reminds a spray cooler, differs significantly from it regarding its operation principle, since very little air is needed in a surface aerator compared to a spray cooler. For example publications US 3669422 and GB 862761 disclose surface aerators and publication GB 964590 discloses a slurry handling device. These are not spray coolers, and they do not have properties typical for a cooler. Their solutions do not, for example, enable bringing large amounts of air in connection with the water spray.

OBJECT OF THE INVENTION

The object of the present invention is to reduce or even eliminate the above- mentioned problems appearing in prior art.

An object of the present invention is to achieve a reliable spray cooler, which is located on the surface of the water and operates more efficiently than before.

BRIEF DESCRIPTION OF THE INVENTION

In order to achieve, among others, the objects mentioned above, the water spray cooler and the method for cooling water and other objects of the invention are characterised by what is presented in the characterising parts of the enclosed independent claims.

The embodiment examples and advantages mentioned in this text apply, when applicable, both to the water spray cooler, method and other objects according to the invention, even though it is not always specifically mentioned.

A typical spray cooler to be arranged on the surface of the water comprises a frame and supported thereon

- a suction pipe, the lower end of which can be arranged below the surface of the water and the upper end above the surface of the water,

- a pump for bringing the water to flow into the lower end of the suction pipe and out of the upper end of the suction pipe, which pump comprises a propeller arranged to be rotatable around the mainly vertical axis,

- a centrifugal sprayer for generating a water spray away from the spray cooler, which centrifugal sprayer is located least mainly above the upper end of the suction pipe and rotatable around said axis, which centrifugal sprayer comprises an upwards expanding upper cone located on the axis and blades located on the downwards facing cone surface of the upper cone,

- a power source, such as an electric motor, which is arranged to rotate said axis and thus the propeller and the centrifugal sprayer.

The power source, such as an electric motor, is located above the upper cone and supported on the frame, for example on the floats, by legs. The legs or at least a part of the legs can be supported on the frame at the upper cone or below the upper cone.

The horizontal cross-section of the legs is longitudinal at the upper cone in the direction of the water spray. In other words, in the direction of the spray, the cross-section is wider, i.e. longer than in the adversarial direction of the water spray, i.e. in the transversal direction in relation to the water spray. Thus, the cross-section of a leg can be said to be asymmetrical, for example so that the other side of the cross-section is longer than the other. One way of describing the invention is that the horizontal cross-sections of the legs are as small as possible in a perpendicular direction in relation to the water spray. The cross-section of the leg can be longitudinal, for example mainly rectangular, for example plate-like or oval-shaped. The cross-section of the leg can be a triangle, the angle or the short side of which is towards the water spray. The leg can be made of metal, such as steel plate or metal bar. The leg can be made of a pipe, for example of a pipe having an oval-shaped cross-section. The legs can, for example, be made of flat bar iron, the thin side of which is towards the spray. Thus, the legs cover only a small part of the water spray thereby intensifying the cooling.

Generally, the spray cooler comprises floats for keeping it on the surface of the water. The spray cooler is generally supported on its place for example by chains or wire cables. It is also possible to support the spray cooler to an appropriate height with some kind of a support arrangement.

A typical method according to the invention for cooling water with a spray cooler arranged on the surface of the water comprises at least the following steps:

- suction pipe is kept in water, so that the lower end of the suction pipe is below the surface of the water and the upper end is above the surface of the water,

water is pumped into the lower end of the suction pipe upwards in the suction pipe and out of the upper end of the suction pipe, with a pump, which comprises a propeller rotating around the mainly vertical axis,

- water is guided from the upper end of the suction pipe towards the centrifugal sprayer located above the upper end of the suction pipe, which centrifugal sprayer is rotated around said axis and thus a water spray is generated away from the spray cooler. The centrifugal sprayer comprises an upwards expanding upper cone located on the axis and blades located on the surface of the upper cone, wherein in the method water is guided to the blades of the upper cone along the upwards expanding cone surface of the upper cone,

- rotational power of the axis, i.e. the pump propeller, and of the centrifugal sprayer is generated with the same power source, such as an electric motor, connected to the axis. The power source is supported on the frame above the upper cone with legs.

The horizontal cross-section of the legs is at the upper cone longitudinal in the direction of the water spray, wherein in the method

- water spray is guided pass the legs in the longitudinal direction of their horizontal cross-section.

One big advantage of the invention is the intensification of dropping and thus cooling. The form of the upper cone keeps the water flowing upwards from the suction pipe near the surface of the cone, whereby only a small part of the water can flow pass the blades. Thus, the structures located above the water, i.e. the upper cone with its blades, sprays the water coming from below effectively into drops, which spray 360° around the cooler. The spray formed by the drops is easy to be guided diagonally upwards to the sides with the aid of the cone surface and the blades. If desired, it is possible to guide even all the water diagonally upwards, for example 10— 60 degrees upwards from the horizontal plane. Thus, the spraying routes of the drops can be made to form a large cross-section in the vertical direction. The large amount of drops sucks a large amount of dry air with it from above the device. The structure according to the invention is easy to be made open, so that it allows the water to spray to all directions around the device and on the other hand enables the flowing of large amount of air. When the drops and the air meet, water is evaporated and the temperature of the drops and thus of the entire water spray sinks effectively.

It is important for the spray cooler, that the water spray takes a huge amount of dryer air with it from above the cooler and guides it to the sides. The structure of the device tries to guide dryer air from above the device so as to be in connection with the water. The legs according to the invention located on the way of the water spray are placed in relation to the water spray so, that they form a cross-section as small as possible towards the spray. An increase of efficiency of the cooling of even tens of percent has been surprisingly achieved in the tests, when legs having a circular or quadratic cross-section are formed in their cross-section asymmetrically so, that the shortest side of the cross-section is towards the spray, although the cross-sectional area of the legs was kept substantially the same. In a device according to the invention the water spray can spray freely and the blind spots in the water spray caused by the legs remain small. For example, with the legs according to the prior art having a circular cross-section, a blind spot of over 30% can be caused to the spray by the legs. It seems, that the drops bouncing from the legs weaken the entire spray also where no blind spots are formed.

In an embodiment, the legs are at the spray sufficiently far away, for example in a distance of over 15 cm, or over 30 cm, or over 45 cm, or over 60 cm, from the upper cone and its blades. Thus, the legs cover only a small part of the water spray thereby further intensifying the cooling. From an appropriate distance, the sprays also prevent the legs from getting dirty, i.e. wash the legs.

In an embodiment, the horizontal cross-sections of the legs are according to the invention longitudinal along the height of the entire upper cone or along the height of the entire water spray. In other words, the legs are in such position, that the horizontal cross-sections of the legs are as small as possible along the height of the entire water spray in the perpendicular direction in relation to the water spray. The water spray is thus guided along its entire height pass the legs in the longitudinal direction of the horizontal cross-section.

In an embodiment, a bladeless section has been arranged on the axis between the pump propeller and the upper cone. The bladeless section allows a free flow of the water efficiently inside the suction pipe thus intensifying also dropping and cooling. In an embodiment, an upwards expanding intermediate cone has been arranged on the axis between the pump propeller and the upper cone. When water is guided upwards in the suction pipe in a controlled manner along the surface of the intermediate cone before guiding the water to the upper cone, the dropping and cooling are intensified.

The diameter of the lower end of the intermediate cone is typically smaller than the diameter of the propeller pump. In an embodiment, the lower end of the intermediate cone has approximately the same diameter as the propeller hub. In an embodiment, the diameter of the upper end of the intermediate cone is smaller than or equal to the diameter of the lower end of the upper cone. A controlled extension of the diameter of the cone surface from the pump propeller towards the upper cone intensifies the operation of the device.

In an embodiment, the spray cooler comprises an upwards expanding guiding cone arranged in the upper end of the upper cone, the diameter of the upper edge of which guiding cone is larger than the diameter of the upper edge of the upper cone. Thus, that part of the water, which bypasses the cone surface and the blades, can be guided diagonally upwards away from the spray cooler along the surface of the guiding cone.

In some embodiments, two or more cones, i.e. an upper cone and a guiding cone or an upper cone and an intermediate cone or an upper cone, guiding cone and an intermediate cone are one and the same piece.

In an embodiment, the angle, by which the cone expands upwards, changes along the course of the cone. In an embodiment, in the connection point of the adjacent cones, the extension angle changes sharply, in other embodiments the extension angle changes in the connection point gradually, i.e. in a rounded manner. In an embodiment, the guiding cone expands upwards more sharply than the upper cone.

In an embodiment, the upper edge of the guiding cone and/or the edge of one or more blades is serrated or notched. The serration and/or the notching have an impact on the dropping and on the shape of the water spray to be formed. This way, the dropping and the water spray and thus the cooling can be controlled as desired by adjusting the form of the edge to conform any situation. In some embodiments, the cooling is intensified by guiding the water flowing along the surface of the upper cone with blades, which are in relation to the flow direction of the water substantially inclined, curved or in different directions in relation to each other. Thus, the water spray expands effectively and vertically as desired. If a blade is inclined, so that the lower edge and the upper edge of the same blade are not at the same vertical imaginary plane travelling through the axis, it guides the water spray to a different direction than a vertical blade, i.e. a blade located in the direction of water flowing upwards from below from the suction pipe, would do. In an embodiment, the blades are in different positions to each other, so that the angle between the blades and said imaginary vertical plane varies, whereby the different blades direct water sprays in a different way. In an embodiment, one or more blades are curved, whereby one and the same blade directs the water spray in several directions. Also the distance, which the water travels from the spray cooler, and thus the energy consumption, can be impacted by inclined and/or curved blades. In an embodiment, the blades are inclined or curved backwards, i.e. so that the lower edge of the blade travels in the rotational direction of the upper cone of ahead the upper edge of the blade. This improves the efficiency of the device and enables an effective direction of the water spray diagonally upwards. In an embodiment, the efficiency of the cooler is steplessly guided by guiding the efficiency of the electric motor with a frequency transformer. In an embodiment, there are more blades in the upper cone than there are propeller blades in the lower propeller. This way, it is ensured that the water spray is formed efficiently. There can be, for example 2— 5 or 3— 4 propeller blades in the lower propeller. The upper cone can have for example more than 3 blades, more than 4, more than 6, or 3—12, 4—10, 6— 8 or 6—10 blades.

The uses of the spray cooler according to the invention can be for example cooling of industrial process waters and turbine waters of thermal power stations. BRIEF DESCRIPTION OF THE FIGURES

The invention is described in more detail below with reference to the enclosed schematic drawing, in which

Figure 1 shows a cross-section of a spray cooler seen from the side,

Figure 2 shows a spray cooler seen from the side,

Figure 3 shows a spray cooler seen from above,

Figure 4 shows a horizontal cross-section of the upper cone,

Figures 5a— 5c show blades of the centrifugal sprayer,

Figure 6a— 6c show centrifugal sprayers,

Figure 7 shows a centrifugal sprayer,

Figure 8 shows another spray cooler seen from above.

DETAILED DESCRIPTION OF THE EXAMPLES OF THE FIGURES

For some parts corresponding to each other, same reference numerals are used in different examples for the sake of clarity.

In Figure 1 is shown a spray cooler 1 according to the invention, which has a frame 2 and supported thereon a suction pipe 3, propeller pump 4, centrifugal sprayer 5 and an electric motor 6. The electric motor rotates the vertical axis 7 and thus also the propeller pump 4 and the centrifugal sprayer 5, which are attached to the axis 7. The spray cooler 1 floats in water, for example in a process water basin of an industrial plant. The lower end 8 of the vertical suction pipe is below the surface of the water 9 and the upper end 10 is above the surface of the water or approximately on the same plane with it. The pump propeller 1 1 is inside the suction pipe. The propeller 1 1 has a hub 28 and propeller blades 29. The centrifugal sprayer 5 is located above the upper 10 end of the suction pipe. In the centrifugal sprayer 5 there is an upwards expanding upper cone 12 located on the axis 7 and blades 14 located on the downwards facing cone surface 13 of the upper cone. A guiding cone 15 expanding more sharply upwards than the upper cone has been attached to the upper edge of the upper cone. An upwards expanding intermediate cone 30 is located between the upper cone 12 and the propeller 1 1 . The frame 2 comprises the floats 16 and the legs 17, which keep the electric motor above the device and are supported on their lower end to the float. In Figure 1 , there are also shown a frequency transformer 18, with which the efficiency of the electric motor is guided, and a current conductor 19.

The operational principle of the spray cooler 1 can be seen i.a. in the examples of Figures 2 and 3. The electric motor 6 rotates the axis 7 and along with it the propeller 1 1 of the propeller pump 4 located below the surface of the water 9 and the centrifugal sprayer 5 located above the surface of the water 9. When rotating, the propeller 1 1 lifts water upwards in the suction pipe 3. Above the surface of the water 9 there is a rotating upper cone 12 of the centrifugal sprayer 5, and on the lower surface of the upper cone there are centrifugal blades 13, on which the water hits. The guiding cone 15 guides the part of the water bypassing the upper cone 12 and the blades 13 diagonally upwards in a controlled manner. The structure above the water, i.e. the upper cone 12, the blades 13 and the guiding cone 15, sprays the water flowing from below into drops, which spray as a water spray 20 horizontally 360°, i.e. to all directions around the spray cooler 1 . A large amount of drops and an open structure of the spray cooler 1 enable the water spray 20 to take a large amount of dry air 21 with it from above the spray cooler. When the drops and the air meet, water is evaporated and the temperature of the drops and thus of the entire spray sinks effectively, since the evaporation binds a lot of energy. Significant factors for an efficient cooling are i.a. spraying a large amount of water, spraying the water into drops, sufficient velocity of the drops, sufficiently long spraying route of the drops, large cross-section of the water spray. The water flow to be pumped into the cooler is illustrated by arrows 22 and the rotation direction of the axis 7 in the Figure by arrow 23.

In the example of Figure 3 there are drawn an imaginary circle 24 formed by the water spray, horizontal cross-sections of four legs 17 and a circular float 16, in the opening located in the middle of which the rest of the device is located. The outer diameter of the float can be for example 1— 2 meters. The legs 17 located in front of the water spray 20 prevent the water spray 20 at their location. In order to reduce this blind spot effect the legs are formed longitudinal in their cross-section. Due to the rotational movement of the axis 7 and the upper cone 12 of the centrifugal sprayer the water spray 20 is not directed away from the centre of the device at the legs 17 in the direction of the radius of the circle 24. Therefore, the legs 17 are placed diagonally in the manner illustrated in Figure 3, so that the longitudinal direction of the cross-section of the leg is at an angle of approximately 45 degrees in relation to the direction of the above-mentioned radius. This direction of the leg can be set to conform each situation, for example to 30—60 degrees.

Figure 4 shows an example of the horizontal cross-section of the upper cone 12. The blades 14 located on the surface 13 of the upper cone 12 are at an angle of approximately 45 degrees in relation to the direction of the horizontal tangent of the surface 13. In the embodiments of the invention, this angle can be for example 10— 90 degrees or 30— 60 degrees. Blades arranged in different position in relation to the surface of the upper cone can be located on the same upper cone. The smaller the angle is, the smaller is the resistance of the water and the energy consumption. The magnitude of the angle impacts the direction of the water spray to be formed and to the efficiency of dropping. Arrow 23 describes the rotational direction of the upper cone, arrow 26 describes the movement of the water on the surface 13 of the upper cone and arrows 20 describe the water spray to be formed. The blade 14 according to the invention can be variable in its angle in relation to the tangent of the surface 13 of the upper cone for example so, that in the lower end of the blade the blade is in the direction of the tangent, but for example in its upper edge in the angle of 30— 60 degrees or approximately 45 degrees in relation to the horizontal tangent of the surface 13.

Figures 5a— 5c show some examples of the blades 14 of the centrifugal sprayer 5 and Figures 6a— 6c show corresponding blades 14 at the upper cone 12 seen from the side. Arrows 31 have been drawn to Figure 5a to describe the flow direction hitting the blade 14. The blades 14 can be for example vertical seen from the side (Figs 5a and 6a), inclined backwards (Figs 5b and 6b) or curved or otherwise variable in their angles (Figs 5c and 6c). The same upper cone 12 can have blades 14 being in different positions and/or having different shapes. With the different positions and shapes of the blades, different shapes of water sprays and different kind of dropping are achieved.

Figure 7 shows an example of the centrifugal sprayer 5, in which recesses or a serration 27 have been formed to the edges of the blades 14 and the guiding cone 15. Thus, the water flow can be effectively sprayed into drops, whereby the cooling is intensified. The dropping can also be intensified by forming grooves to the surface of the blades and/or the guiding cone.

In the example of Figure 8A is shown a spray cooler 1 according to the invention as seen from above. The spray cooler 1 corresponds in its structure mainly to the example of Figures 1— 3. An electric motor 6, to which four legs 17 supporting it have been fastened, is seen in the middle of the circular float 16. The legs 17 are made of flat steel and mounted so that the water spray 20 spraying from the middle of the device 1 is restricted as little as possible. The upper ends 40 of the legs have two legs. But along the lower mainly vertical section 41 in front of the water spray, the legs 17 consist of one thin steel plate, the horizontal cross- section of which is longitudinal in the direction of the water spray 20. On the outer edge of the float 16 there are lugs 42 for anchoring the device. Since the lower mainly vertical section of the entire leg has a flat form, the horizontal cross- section of the leg 17 is longitudinal in the direction of the water spray along the entire height of the water spray 20. It is not intended to limit the scope of the invention to the examples mentioned in the application, but the scope is defined by the independent claims.