FIELD OF THE INVENTION
[0001] The invention consists of a rotor improving the performances of a spray nozzle for
water to be cooled in a cooling tower, since it allows an unform distribution of the
water coming out from the nozzle outlet on the inner section of the tower and in particular
on the upper surface of the heat exchange element normally contained in a cooling
tower in order to increase the water/air contact surface and then the cooling efficiency.
PRIOR ART
[0002] A cooling tower is a particular cooling plant used in numerous fields of technics
and industry (thermoelectric, petrochemical etc.) to dissipate the heat present in
the cooling water.
[0003] In the cooling towers the water to be cooled is sprayed on the tower top and during
its falling it meets an air stream to which it transfers a heat quantity by partially
vaporizing.
[0004] Said air stream may be generated by one or more sucking fans placed on the tower
top and/or by one or more blowing fans placed on the cooling tower bottom, or this
air stream could be generated by the natural draught due to air density differences.
[0005] The evaporation allows to cool the water to a temperature lower than the air inlet
temperature. In order to increase the air/water contact surface, and then the cooling
tower efficiency, the tower casing is at least partially filled with one or more layers
of a "honeycomb" material (or of another equivalent material) which foresees an upper
chamber where a plurality of spray nozzles are placed and a lower chamber where a
sink for collecting the cooled water is placed.
[0006] Coooling towers provided with spray nozzles having means suitable for more uniformly
distribute water which has to be cooled on the whole inner section of the tower are
known in the art.
[0007] In a possible embodiment (e.g. as described in US-A-5 143 657) said distributing
means comprises at least a disk-shaped mobile element, showing a plurality of fins
on both sides, which is rotated by the water to be cooled coming out from the nozzle
and urging the fins present on one side; in this case the centrifugal force spreads
out said water on a larger surface. Said known distributing elements are quite expensive
and complicated since for instance the mobile element is kept by means of a fixed
element receiving a part of the water to be cooled through a hole placed in the center
of the mobile element. In this case, a part of the water urging the fixed element
is further dispersed and the balance is deviated towards the fins present on the other
side of the mobile element; these fins spread out the coming water by means of the
centrifugal force.
[0008] The fixed element is kept in its housing by a tension rod passing through the hole
present in the mobile element and it is fixed to a stand present in the inner side
of the spray nozzle. Said stand and the relative fixing means to the nozzle must be
strong enough to bear the action of the water which has to be cooled coming out from
the nozzle and they reduce the nozzle free section and the hole section present on
the mobile element.
[0009] According to a further embodiment of the known distributing means (easier to realise
than the previously described embodiment), the water to be cooled coming from the
nozzle passes through the hole present on the mobile element and urges a slightly
curved plate (which constitutes the fixed element) which deviates it towards the fins
present on the correspondent side of the mobile element, said fins rotating the mobile
element which spreads out the water to be cooled by centrifugal force.
[0010] By using the known distributing elements which perform an essentially radial distribution,
the water to be cooled can not properly wet the part of the heat exchange element
immediately underlying each nozzle; in this case, around a third of the surface affected
by each spray nozzle is wet by the water to be cooled in an inadequate manner.
[0011] Moreover, the mobile element of the known distributing elements can be stopped by
foreign bodies and/or by scales of the mineral salt normally present in the water
for industrial purposes used as cooling water in the plant comprising the cooling
tower, said foreign bodies and/or scale being removable only by cutting off the cooling
tower and disassambling the distributing elements.
[0012] An object of the present invention is a rotor suitable for a spray nozzle for cooling
tower which allows to overcome the foresaid drawbacks shown by the known distributing
means.
SUMMARY OF THE INVENTION
[0013] Object of the present invention is a rotor for a spray nozzle working in a cooling
tower which is substantially conically shaped and has its vertex directed towards
the outlet section of the spray nozzle.
[0014] The water coming out from the outlet section urges a multiplicity of fins realized
on the rotor surface causing the rotation of the rotor itself around a pin fixed to
the external wall of the nozzle.
[0015] In the main body of the rotor, starting from the external edge, one or more cavities
are provided, which are equidistant, and have a profile equal to the one of the fins.
Each cavity is realised on a part of the rotor main body comprised between two adjacent
fins.
LIST OF FIGURES
[0016] The invention will be better understood with reference to a non-limiting embodiment
shown in the enclosed drawings, where :
- Figure 1 shows a top view of a rotor according to the present invention;
- Figure 2 shows a cross-section along plane A-A of Figure 1 of the above rotor ;
- Figure 3 shows a lateral view of the rotor shown in Figure 2 mounted on a stand projecting
from the nozzle supporting it from the top;
- Figure 4 shows a lateral view of the rotor shown in Figure 2 mounted on a stand able
to support it from the bottom.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] Figure 1 shows a top view of the rotor according to the present invention, whereas
Figure 2 shows a cross-section along a plane A-A of the above rotor. In said Figures
it is possible to see the hub 1 showing a through hole 2 receiving a pin 9 (Figures
3 and 4) which constitutes the rotor rotation axis and eight fins 3, equidistant each
other, shaped as arcs of circunference till the rotor edge.
[0018] The fins 3 have constant height and thickness and are connected to the rotor hub
1, which therefore is shaped as a cone gradually transformed into a multiplicity of
identical curvilinear arms.
[0019] The eight fins 3 divided the main body 4 of the rotor in eight parts, in each of
them, starting from the rotor external edge, a cavity is provided. The eight cavities
may be grouped in two groups of four cavities 5, 6, 7, 8 of different depth, uniformly
disposed on the rotor; in this case, two identical cavities appear perfectly symmetric
as regards the rotor hub 1.
[0020] The water coming out from the rotor outlet urges and rotates the rotor, generating
a distribution cone which may be schematically decomposed into four concentric parts,
each part being created by the water passing through the cavities of each series which
are decreasingly deep, and into a fifth outer part concentric with the other ones
created by the water which completely follows the fins 3 and is dispersed more distant
from the nozzle by the centrifugal force. In particular, the water flowing through
the deeper cavities 8 goes out the rotor action creating the central part of the distributing
cone which wets the part underlying the nozzle, preventing the serious drawback of
the known distributing devices.
[0021] Accordingly, a rotor according to the present invention works correctly even if no
cavity is provided in some of the parts in which it is divided by the fins 3 whereas
it is necessary (or at least suitable) that at least a fin is present between two
contiguous cavities: it is therefore necessary (or at least suitable) that the number
of cavity realized in the rotor main body 4 is equal or at least not higher than the
number of the fins 3.
[0022] A rotor according to the invention has also the advantage to be self-cleaning, since
the action of the water jet, the absence of mobile parts around the rotor and the
fact that the fins 3 are gradually linked to the hub 1 assure that a foreign body
present in the water to be cooled does not stop on the rotor and that the rotor itself
can not be stopped by scales of mineral salts normally present in the cooling water.
[0023] Figure 3 shows a lateral view of the rotor, where the rotation hub 9 is constituted
by the terminal portion of a stand 10 (or it is fixed in any manner to said stand
10) which is cantileverly fixed to the external wall of the nozzle 11 and which supports
the rotor from the top.
[0024] To deviate the water flow and to prevent the settlement of scale in the seat for
the rotor hub 9, a protection cap 12 is provided above the rotor; furthermore, on
the hub 9 washers 13, 14 are provided, these last ones being in a material having
suitable frictional resistence and preferably of self-lubricating kind.
[0025] The stand 10, fixed out from the nozzle 11, does not need fixing means particularly
strong, does not reduce the outlet section of the nozzle 11 and does not interfere
with the free water flowing from the nozzle itself.
[0026] The Figure 4 shows a lateral sectional view of the rotor whose rotation hub 9 is
supported by a stand 15 bearing the rotor from the bottom; the main body 4 of the
rotor protects the seat of rotor receiving the hub 9 against foreign bodies and/or
scale.
[0027] On the contact surface between the stand 15 and the rotor it is suitable to use washers
13, 14 in a material having a suitable frictional resistence and being preferably
self-lubrificant. The cap 16 makes easier the water flowing along the main body 4
of the rotor; in this case, the stand is less stressed.
[0028] The rotor formerly described only as non-limiting example includes eight fins and
two series of four cavities, however, without going out from the scope of the present
invention, a skilled person may modify said rotor by realizing a different number
of fins 3 and/or series of cavities and/or cavities for each series (anyway the number
of the cavities must be equal or at least not higher than the fins number) and by
including any further modification and improvement suggested by the normal experience
and by the natural progress of the technics.
1. Rotor for spray nozzle for cooling tower, characterized in that it is substantially
conically shaped with the vertex directed towards the outlet section of said nozzle
(11), in that a plurality of fins (3) is present on its surface urged by the water
going out from said outlet section, the action of said water on said fins (3) rotating
said rotor around a pin (9) fixed to the external wall of said nozzle (11) and in
that in the main body (4) of said rotor there are, starting from the external edge,
at least a series of cavities (5-8) of different depth, equidistant each other, whose
profile is similar to the fins (3) one, each of said cavities (5-8) being realized
in a part of said main body (4) of said rotor comprised between two adjacent fins
(3).
2. Rotor according to claim 1, characterized in that said fins (3) having constant section
and constant height are arc-shaped.
3. Rotor according claim 1, characterized in that it comprises eight fins (3) and two
series of cavities, each of them comprising four cavities (5, 6, 7, 8) of different
depth.
4. Rotor according claim 1, characterized in that it is supported from the top by said
rotation pin (9) fixed to a stand (10) cantileverly fixed to the external wall of
said nozzle (11).
5. Rotor according claim 1, characterized in that it is supported from the bottom by
said rotation pin (9) carried by supporting means (15) fixed to the external wall
of said nozzle (11).
6. Rotor according claim 1, characterized in that the number of said cavities is not
higher than the number of said fins (3).