The invention relates to a fluid cooling system, particularly for cooling towers, comprising a liquid distribution system.
Cooling towers and hence also fluid cooling systems for cooling towers are known per se in prior art so that separate documents need not be cited at this point.
Normally in fluid cooling systems, a liquid is moved past a gas, for the purpose of energy transfer and with the intention to cool either the liquid or the gas. Vice versa, the intention can also be to heat one of the two fluids that are moved past one another, while the principle structure of the fluid cooling system is the same. In this case, a fluid heating system is involved. To achieve a heat transfer between the two fluids which is as good as possible in either case, a liquid distribution system is regularly provided, by which the liquid is distributed as evenly as possible over the cross section of the system in the apparatus. If the liquid is not completely evaporated or volatilized within the system, the remaining liquid can be collected in a suitable collecting device.
Cooling towers are intended to cool a fluid such as a liquid. Though the fluid to be cooled is mostly water, also acid cooling towers are used, i.e. acid is cooled in the cooling tower using ambient air and also applying the principle of evaporation cooling. But also other liquids or gases can be cooled in a cooling tower. A further important embodiment are cooling systems or cooling towers in which as a process objective, air such as ambient air is cooled and/or humidified using water and also applying the principle of evaporation cooling.
In the following, one of the most commonly used cooling tower constructions will be described in more detail. These cooling towers cool liquids—very frequently water—using ambient air, and they preferably have cooling installations which are intended to improve the cooling-down of the water. On the other hand, cooling towers without cooling installations are used in order to avoid permanent soiling or clogging of these cooling installations if the liquids are soiled or in the case of considerable depositions during the cooling process.
The liquid to be cooled is sprayed above the cooling installations using a liquid distribution system and trickles along the cooling installations and downwards while following the force of gravity. Air flows through the cooling installations, e.g. in a counter flow to the liquid to be cooled, for the purpose of cooling. As a result of the contact of the liquid to be cooled with the cooling air within the cooling installations, the liquid to be cooled is cooled down as intended.
The above-described construction of a cooling tower which is also referred to as a natural draught cooling tower and which is known per se in prior art, is disclosed for example in DE 10 2006 005 114 A1.
In a different embodiment, the cooling installations in the cooling tower are replaced by a heat exchanger that is sprayed with water from a distribution system arranged above the heat exchanger. The heat of the fluid flowing through the heat exchanger is transferred to the cooler trickling water that trickles through the heat exchanger and flows around its outer surfaces. The ambient air introduced in the cooling tower absorbs the heat from the trickling water through evaporative cooling. Here the process objective is the efficient cooling of a fluid (water, steam, oil, cooling agents etc.) in a closed cooling circuit, without this internal fluid being contaminated or allowed to escape to the surrounding area. Such a prior art device is disclosed as an evaporative cooling tower in EP 0 687 878 B1.
It principally applies that the uniform distribution of the liquid has a positive effect on the achievable cooling. A more even admission of the liquid inside the cooling tower also reduces the pressure loss of the cooling air. Accordingly, the aim is to achieve a liquid distribution which is as even as possible.
Liquid distribution systems have become known in prior art which for the purpose of a distribution of the liquid which is as even as possible include so-called “plate-type nozzles”. Such “plate-type nozzles” are known for example from DE 690 04 554 T2.
In the embodiment according to DE 690 04 554 T2, a “plate-type nozzle” has a connecting pipe that is connected to a manifold of the liquid distribution system. If the system is used as intended, the liquid to be cooled freely flows/from the connecting pipe. Below the exit of the connecting pipe, in the height direction, a disc-like plate is arranged with a certain distance to the connecting pipe. Normally, this distance has to be 0.8 m to 1.2 m and thus is relatively large. If the system is used as intended, the liquid to be cooled leaves the connecting pipe and impinges on the plate (also referred to as “baffle plate”) of the “plate-type nozzle”.
The liquid jet which vertically impinges on the baffle plate is split up into strands, films and drops in a highly irregular fashion. The torn-open and split-up liquid volume is directed in an arc shape to all sides by the baffle plate. Film-like umbrellas are formed which achieve a relatively large spray range of several meters distance. But vast areas below these umbrellas remain dry.
Since cooling towers normally require a plurality of such plate-type nozzles for distributing the liquid and since these nozzles are arranged with a small distance of e.g. 1 m from each other within the grid, an overlapping of the spray patterns of adjacent plate-type nozzles is achieved. This overlapping reduces the very bad liquid distribution of the individual plate-type nozzles. Up to present, the results obtained by these distribution systems and the accompanying cooling actions (cooling data) have been deemed acceptable. But what remains is the general problem of insufficient evenness of the liquid distribution over the entire cross section of the cooling tower.
Furthermore, so-called “swirl nozzles” are known in prior art, e.g. in DE 78 23 070 U1. A “swirl nozzle” is a nozzle equipped with a swirling device and the swirling device can be designed in the form of a swirl plate, swirl vane, swirl pin and/or the like. The “swirl nozzle” known from DE 78 23 070 U1 has a swirling device in the form of a pin. This pin is centrally arranged inside the nozzle chamber and is centrally aligned with the exit opening so that the nozzle chamber, the swirl pin and the exit opening lie on a common axis. The purpose of the pin is to give the liquid expelled from the “swirl nozzle” a substantially conical profile.
“Swirl nozzles” and accordingly also the nozzle which is pre-known from DE 78 23 070 U1 have the disadvantage that the nozzles become easily clogged due to dirt. For this reason, “swirl nozzles” require regular and frequent inspection and cleaning, which is labor-intensive and thus expensive. Moreover, the swirling devices of “swirl nozzles”, if used as intended, cause a high pressure loss, so that correspondingly high initial pressures are required. The pumping energy, the larger pump construction size etc. which are involved, clearly increase the cost of the entire system. This is the reason why such swirl nozzles are not employed above all in power plants but also in chemical plants and steel mills, which are characteristic of huge volumes of circulated water and huge overall cooling systems.
Although “plate-type nozzles” as known in prior art have proved and tested in everyday practical use, there is a need for improvement. For example, the “plate-type nozzles” known in prior art do not render a satisfying water distribution. A further drawback is that a relatively large spray height is required, i.e. a relatively large spacing between the “plate-type nozzles” and the cooling installations or heat exchangers.
Based on the above, it is an object of the invention to further develop a fluid cooling system of the above-described type in such a way that a liquid distribution is achieved which is as even as possible while avoiding the above-described drawbacks.
To solve this object, the invention proposes a fluid cooling system, particularly for cooling towers, comprising a liquid distribution system having a plurality of distributor pipes connected to a feed pipe and equipped with tangentially attached full cone nozzles, each full cone nozzle comprising a nozzle housing that provides a rotation-symmetrically configured nozzle chamber, a connecting piece ending into the nozzle chamber, a nozzle mouth that is located downstream of the nozzle chamber and defines an outlet port, and a housing lid for the nozzle chamber, wherein the housing lid supports extensions on the inside thereof facing the nozzle chamber that project into the nozzle chamber, wherein the connecting piece is aligned at right angles to the rotational vertical axis of the nozzle chamber and offset therefrom, and wherein the outlet port is directed to the connecting piece and offset with respect to the rotational vertical axis of the nozzle chamber.
The fluid cooling system according to the invention is characterized by a specially designed liquid distribution system. This liquid distribution system comprises a plurality of distributor pipes. These are connected to a common main distribution passage that is fed by a feed pipe. The distributor pipes are preferably aligned with an equal distance to one another.
The distributor pipes are equipped with full cone nozzles tangentially attached to the distributor pipes. Each full cone nozzle has a nozzle housing that defines a nozzle chamber that is designed rotation-symmetrically and cylindrically with respect to its cross section.
For introducing water into the nozzle, a connecting piece is provided which is preferably formed as one piece with the nozzle housing. The connecting piece ends tangentially in the nozzle chamber and the latter is aligned at right angles to the rotational vertical axis of the nozzle chamber and offset therefrom. Accordingly, a water jet which is introduced tangentially through the connecting pipe, enters the nozzle chamber off-center and at right angles to the vertically downwardly arranged outlet opening. As a result, a rotational or swirling movement is produced, and this without the use of a swirling insert or the like that blocks or constricts the liquid flow.
The nozzle construction accordingly has continuously large and free flow cross-sectional areas for the liquid flow, thus avoiding any considerable contamination or even clogging of the nozzles during many years of continuous duty in the industry. The operational problems that have been mentioned lead to a significant loss of performance and even to a complete failure of the cooling system, which is precisely avoided by the configuration according to the invention.
Due to the arrangement of the connecting pipe at right angles to and offset from the rotational vertical axis of the nozzle chamber, the water which is tangentially introduced into the nozzle housing through the connecting pipe is subject to a rotational movement, is redirected by 90° and leaves the nozzle chamber through the nozzle mouth adjoining the nozzle chamber in the flow direction and defining an outlet opening while performing a rotational or swirling movement that is produced due to the above-described design.
The lid of the nozzle housing opposite to the nozzle mouth closes the nozzle chamber toward the upper side. The lid area can also be integrally formed with the nozzle housing. The lid preferably seals against the housing body which is formed in a corresponding manner on its upper rim, via a bayonet joint or an inserted O-ring.
The housing lid has extensions, also called attachments, which project inwardly into the nozzle chamber and which are tangent to the liquid tangentially flowing into the nozzle chamber in a suitable manner from above. The rotation-symmetrical liquid flow produced in the nozzle chamber is thus induced to produce a full cone flow at the time of leaving the nozzle mouth. The full cone flow is advantageous with respect to the evenness of the liquid distribution produced by the nozzle.
The attachments of the housing lid are uniformly and regularly spaced to each other with a distance of e.g. 20 mm. This avoids clogging of the intermediate spaces. The lid can be easily detached, cleaned and attached again and thus constitutes a highly practical construction detail. Preferably, the attachments have a triangular cross section, which assists the above-described swirl effect.
The particular advantage of the design according to the invention resides in the fact that an even distribution of the water is accompanied by only a small pressure loss, so that the liquid distribution systems operates with a low energy loss.
For producing a water swirl, prior art cone nozzles comprise a swirl blade, swirl plate or a similar swirling device. Such a swirling device has the drawback of involving pressure losses, so that correspondingly high input pressures are required for achieving a desired output pressure. This is not required with regard to the liquid distribution system according to the invention. The same is operated within a range of only 0.04 bar to 0.3 bar above normal pressure—preferably at very low 0.1 bar—and can thus be called a low-pressure distributing system.
Moreover, the fluid cooling system according to the invention is beneficial in as much as it allows an even distribution of the liquid to be achieved, i.e. a spray distribution that is uniform over the entire spray pattern. As a result of the even distribution which is achieved by the system according to the invention, the admission of water to the cooling tower can be uniform, thus advantageously enabling the desired uniform and highly effective cooling of the liquid distributed by the system according to the invention.
The design according to the invention further has the advantage of a comparatively low construction height. For example, the design according to the invention allows an arrangement of the full cone nozzles at a spray height of 400 mm to 800 mm, preferably 500 mm to 700 mm above the cross-sectional area to be sprayed. Thus a construction of the entire fluid cooling system is achieved which is more compact compared to prior art.
Further, in this connection it is provided for the distributor pipes of the fluid distribution system to be aligned to each other with an equal distance and that the tangential full cone nozzles attached to them are mutually positioned with the same distances as the distributor pipes. This advantageously creates a raster or grid of mutually equally spaced nozzles in both axis directions. The nozzles thus achieve a very uniform distribution of liquid in their core areas. In the rim areas, the spray patterns of the respective adjacent nozzles overlap to form an overall spray pattern which is made as even as possible thus making sure that the cross section of the cooling tower is sprinkled as evenly as possible. For obtaining an optimized cooling result, it is provided that the cone nozzles produce a spray cone diameter of 500 mm to 1200 mm, preferably 700 mm to 900 mm. Accordingly, to obtain spray results which are as even as possible, the grid structure formed by the nozzle and distributor pipe arrangement should be designed in such a manner that adjacent nozzles have a distance to each other of approx 700 mm to 900 in both axis directions.
According to a further feature of the invention, the full cone nozzles have an inner side surface roughness of 1 μm to 12 μm, preferably 5 μm to 10 μm. Tests have shown that a certain surface roughness contributes to maintaining the preferred rotation-symmetrical liquid flow, in order to prevent the spray angle from becoming too small and in order to make the distribution of the liquid as even as possible. Particularly good results with respect to the evenness and spray range could be obtained with an inner side surface roughness of approx 10 μm. To respectively obtain a particular surface roughness, it can be provided for the injection mold to be correspondingly pretreated for the manufacturing of the cone nozzles, e.g. by sand blasting.
All in all, the invention proposes a fluid cooling system which thanks to its design achieves a more even distribution of the liquid, which directly results in an improved performance of the entire cooling tower. As a result of the more uniform distribution of the water, the cooling installations or heat exchangers arranged below the liquid distribution system in the direction of gravitation are sprinkled more uniformly, which leads to a more efficient heat and material exchange with the cooling air that is passed through the cooling installations in a counter flow pattern.
According to a further feature of the invention, the full cone nozzles are arranged on the respective distributor pipes with the interposition of a respective adapter. The adapter is designed as a connecting piece having a shoulder with locking tabs on the side of the distributor pipe. Preferably, the connection contour of the shoulder matches the preferred pipe diameters of the associated distributor pipe. For receiving the adapter at the respective grid position, the distributor pipe is provided with a drill hole to be drilled with a relatively narrow tolerance (plus-tolerance).
Further, the adapter is preferably made of a plastic material, e.g. polypropylene, which can be reinforced with glass fibers for reasons of stability. To achieve sufficient elasticity of the locking tabs, the glass fiber moiety must not be chosen to be excessively high. Thus a form-fit connection of the adapter to the associated distributor pipe is obtained.
On the other side, the adapter which is here provided with an internal thread, is screwed to the external thread of the connecting pipe of the full cone nozzle. As a result, a connection of the full cone nozzle to the associated distributor pipe is provided on both sides which is liquid-tight, pressure-proof, positionally secure and durable. Undesired leakages, possible difficulties in mounting and demounting in the case of repairs as well as positionally insecure connections of full cone nozzles on the one side and distributor pipes on the other side can be avoided in this way.
For the arrangement of a full cone nozzle on a distributor pipe as intended, the adapter is inserted in the associated opening of the distributor pipe in a first assembly step. On the side of the distributor pipe, the adapter has locking tabs. The same plunge into the mounting hole formed in the distributor pipe and become locked by an undercut on the distributor pipe wall. On the side of the cone nozzle, the connecting pipe of the cone nozzle is inserted in the adapter and screw-fitted. As a result of this screw-fitting, the locking tabs of the adapter are widened, i.e. radially urged apart, thus providing for a secure support of the adapter with respect to the distributor pipe and hence of the full cone nozzle with respect to the distributor pipe. The contour of the shoulder matches the pipe diameter of the distributor pipe, so that the shoulder snuggles against the outer surface of the distributor pipe in a form-fit fashion.
Further features and advantages of the invention will become apparent form the following description with reference to the drawings wherein it is shown by:
a a detailed view according to the detail IIIa-IIIa in
The fluid cooling system 27 has a liquid distribution system 28 on the one side and, as an example, cooling installations 20 on the other side. In the height direction 29 the liquid distribution system 28 is arranged above the cooling installations 20 or above a cross-sectional area 38 to which a liquid is to be applied in a uniform fashion, as shown in the illustration according to
The liquid distribution system 28 includes a plurality of distributor pipes 24 that are connected to a common feed pipe 23 on the side of the liquid. Preferably, the distributor pipes 24 are equally aligned with respect to each other, which can be seen particularly in the illustrations according to the
Through the cooling tower 19, ambient air is supplied as cooling medium by an axial fan 37 arranged for suction corresponding to the arrows 21 from the bottom to the top with respect to the drawing plane of
The liquid, for example water, to be cooled by means of the cooling tower 19 is introduced into the feed pipe 23 through a supply passage 22. From there the liquid reaches the distributor pipes 24 that are equipped with tangentially attached full cone nozzles 1 for the escape of liquid, which can be seen especially in the detailed view in
The hot water 25 which is evenly distributed via the cooling installations 20 trickles through the same, in the present case in a counter flow to the cooling air 21 that is transported from the bottom to the top. As a result of the trickling water contacting the cooling air, this cooling process, which is implemented using a special cooling tower design, is called an open cooling circuit.
The water thus cooled drips off the cooling installations 20 and is collected in the water collecting tub 39 and from there passed on to the facilities to be cooled.
Furthermore, the cooling tower embodiment which is illustrated herein as an example includes sound absorbers 40 and 41 at the air inlets and at the air outlets.
The particular features of the fluid cooling system 27 according to the invention are the uniform spray distribution caused by the liquid distribution system 28 simultaneously with energy savings which are due to the low pressure loss inside the fluid cooling system 27 and the sturdiness of the system during many years of operation (low maintenance and low repair). Compared to conventional cooling facilities, the fluid cooling system of the invention is characterized by its generally improved efficiency. A further advantage is that full cone nozzles are used in connection with the fluid cooling system 27 according to the invention which enable an operation without using flow constricting swirl plates, vortex generators and the like, whereby the nozzles are normally prevented from clogging. This avoids the loss of performance repeatedly observed in the cooling tower due to a more or less serious clogging of the water distribution nozzles, which may even result in a complete failure of the cooling tower.
A full cone nozzle 1 as used in connection with a fluid cooling system 27 according to the invention is shown in more detail in the
As shown in
The nozzle housing 2 provides a nozzle chamber 5. A connecting piece 4, which is preferably formed as one piece with the nozzle housing 2 and as an injection-molded plastic part, e.g. of glass fiber-reinforced polypropylene, leads into the connecting piece 4. Similarly, also the lid 3 preferably is an injection-molded plastic part. The connecting piece 4 provides a thread 11 that serves for the connection of the connecting piece 4 to a distributor pipe 24 for supplying water. To provide for a tight sealing between a distributor pipe 24 (not shown in
The nozzle chamber 5 is designed in a rotation-symmetrical fashion, as can be seen particularly in the illustrations according to the
The arrangement of the connecting piece 4 at right angles to and offset from the axis of rotation 9 provides that water which is introduced through the connecting piece 4 and through the inlet opening 17 into the nozzle chamber 5 is set into a swirling, i.e. rotational movement about the rotational vertical axis 9 of the nozzle chamber 5. This factual connection can be seen particularly in the illustration according to the
Water which is present in the nozzle chamber 5 leaves the nozzle 1 through the outlet port 15 provided by the nozzle mouth 6. This factual connection can be seen particularly in the illustration according to the
A tapering 8 adjoins the nozzle chamber 5 in the flow direction. The tapering passes into a nozzle neck 7 which is finally joined by the nozzle mouth 6. As can be seen particularly in the illustration according to
As can be seen particularly in the illustration according to
As can be seen particularly in the illustration according to
The nozzle chamber 5, which leads in a funnel-like fashion into the nozzle neck 7 via tapering 8, takes up the water which on the intended use is introduced into the nozzle 1 through the connecting piece 4. Due to the above-described embodiment, the water which is introduced into the nozzle chamber 5 through the connecting piece 4 is supplied to the nozzle chamber on the circumferentially inner side, which results in a rotational movement or swirling movement of the water in the form of a vortex, namely in the right sense with respect to the drawing plane according to
For closing the nozzle housing 2 that is open toward the top, for example with reference to the drawing plane according to
For secure closing, the nozzle housing 2 has on its upper side a locking ring 16 that is formed as one piece with the nozzle housing. This locking ring 16 provides recesses that can be engaged by locking parts 18 of the lid 3 in the fashion of a bayonet joint. Moreover, a groove for receiving the O-ring is worked in the rim of the nozzle housing 2 which forms the locking ring 16. After inserting the O-ring 12 and twisting the lid 3 with respect to the nozzle housing 2, the locking parts 18 formed on the lid 3 grip behind correspondingly formed ramps on the locking ring 16, whereby the lid 3 is tightly and securely pressed against the nozzle housing 2.
As illustrated especially in the
The attachments 14 in the lid bottom are uniformly and regularly spaced by relatively large distances to each other, in order to avoid clogging of the intermediate spaces. The lid as a whole is easy mounting and easy cleaning.
On its inner side, the nozzle housing 2 preferably has a particular surface roughness. This additionally improves the evenness of the spray pattern. In this connection, a surface roughness of approx 10 μm is preferred.
For arranging a nozzle 1 on a distributor pipe 24, an adapter 30 as shown in different views in the
The adapter 30 is formed in the manner of a connecting ring 31. On the side of the distributor pipe it has a shoulder 32 carrying locking tabs 33. In the finally mounted state, the adapter 30 engages with its shoulder 32 in a mounting hole that is provided on the side of the distributor pipe and that has to be manufactured with a tolerance, the adapter 30 becoming locked against the distributor pipe by means of the locking tabs 33 carried by the shoulder 32. Preferably, the adapter is equipped with a connection contour 35 matching the preferred pipe diameters of the associated distributor pipe 24. On the other side, the adapter, which is here provided with an internal thread, is screwed to the external thread 11 of the connecting pipe of the full cone nozzle. Thus a liquid-tight, pressure-resistant, positionally secure and durable connection of the full cone nozzle to the associated distributor pipe is obtained on both sides.
For arranging a full cone nozzle 1 on a distributor pipe 24, the adapter 30 has to be inserted first in the opening of the distributor pipe 24 until it locks in the groove 34 that is provided for this purpose, namely in such a way that the locking tabs 33 project through the opening and into the interior of the distributor pipe 24. Then the nozzle is to be inserted and screwed into the adapter 30 on the other side thereof, until the locking tabs 30 become expanded, i.e. until a radial expansion of the locking tabs 33 takes place. To achieve this, the locking tabs 33 are provided with a ramp 36 on the inner side of the adapter 30. The connecting piece 4 of the associated full cone nozzle 1 peripherally moves up and against this ramp, which results in the above-described radial expansion of the locking tabs 33.
Preferably, the groove 34 has a first groove section 34.1 and a second groove section 34.2. The second groove section 34.2 is formed more deeply than the first groove section 31.1. In the mounted state, the locking tabs 33 of the adapter 30 are supported by the groove section 34.1 of the groove 34, so that a force-transmitting connection between the distributor pipe 24 on the one side and the adapter 30 on the other side is established. In this respect, the groove section 34.1 can also be referred to as a retaining groove or retaining section for the adapter 30.
To assist the radial expansion of the locking tabs on the intended use, the foot sections of the locking tabs 33 include the second groove section 34.2, as plotted as an example in
In the pivoted state, i.e. in the radially expanded state, the locking tabs 33 grip behind the opening formed in the distributor pipe 24, thus producing a force-fit connection that enables a tight and positionally secure arrangement of the full cone nozzle 1 on the associated distributor pipe 24.
The distance of the cone nozzles 1 to the cooling installations 20, i.e. the spray height H and the spray cone diameter D, have to be adjusted to each other so that the final result is an optimized spray distribution, i.e. an even admission of the liquid to be cooled to the cooling installations 20.
Number | Date | Country | Kind |
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20 2008 007 932.2 | Jun 2008 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2009/004270 | 6/13/2009 | WO | 00 | 3/11/2011 |