Cooling tower, particularly of the closed-circuit type

Abstract

 A cooling tower (1), particularly of the closed-circuit type, comprising a hollow body (2) provided with at least one first air intake (3), with at least one second air intake (4) and with at least one main opening (5), so as to form a first air passage circuit and a second air passage circuit which are delimited by the internal walls of the hollow body (2) and extend, respectively, between the first air intake (3) and the main opening (5) and between the second air intake (4) and the main opening (5).
At least one first heat exchanger (6) and at least one second heat exchanger (7) are accommodated respectively along the air passage circuits, are traversed by a fluid to be cooled, and are adapted to transfer heat, respectively, to a first air stream (8) and to a second air stream (9) which converge in the air passage circuits.
At the main opening (5), there are also fan means (14) which are adapted to generate the air streams (8, 9).
The cooling tower further comprises first means (12) for closing the first air intake (3) and second means (13) for closing the second air intake (4), which can be activated selectively to interrupt at least one of the air streams (8, 9).

Description

[0001] The present invention relates to a cooling tower, particularly of the closed-circuit type.

[0002] As is known, cooling towers are used for the cooling of refrigerant liquids that are adapted to cool particular utilities.

[0003] More precisely, the refrigerant liquid is cooled by way of a heat exchanger, generally provided by a tube nest, accommodated within the cooling tower, where it is struck by a flow of forced air taken from the external environment.

[0004] Depending on the characteristics of the air, i.e. depending on its temperature and on the temperature one desires to achieve inside the tube nest, the use is known of two types of heat exchangers using tubes.

[0005] If the temperature of the air is higher, which is the case in summer, it is preferable to use smooth tubes since, under these conditions, they offer the highest heat exchange yield.

[0006] The removal of heat from the liquid inside occurs by evaporation via wetting of the smooth-tube exchanger which is done by a flow of air, in counter-current, taken from the outside.

[0007] Differently, if the temperature of the air is lower, which is the case in the winter, it is preferable to use finned tubes since, under these conditions, they offer the highest heat exchange yield.

[0008] In order to provide a cooling tower that is adapted to function under any climatic conditions, evaporators have been devised that make it possible to lower the temperature of the air, thus enabling the use of heat exchangers with finned tubes also in the hotter and more humid months.

[0009] Such a solution, which obviously results in an increase both in operating costs and in the cost of producing the cooling tower, is however not sufficient to keep the yield of the cooling tower high.

[0010] The aim of the present invention is to provide a cooling tower, particularly of the closed-circuit type, which is adapted to be used both in summer climates and in winter climates, without suffering losses in yield of the heat exchanger or heat exchangers used.

[0011] Within this aim, an object of the present invention is to provide a cooling tower of simple architecture and, therefore, low cost, which is also, thanks to its particular implementation characteristics, capable of offering the widest guarantees of reliability and safety of use.

[0012] A further object of the present invention is to provide a cooling tower that can be easily implemented using elements and materials that are readily available on the market, and which, moreover, is competitive from a purely economical viewpoint with respect to the known art.

[0013] This aim and these and other objects which will become more apparent hereinafter are all achieved by a cooling tower, particularly of the closed-circuit type, comprising a hollow body provided with at least one first air intake, with at least one second air intake and with at least one main opening, so as to form a first air passage circuit and a second air passage circuit which are delimited by the internal walls of said hollow body and extend respectively between said at least one first air intake and said at least one main opening and between said at least one second air intake and said at least one main opening, at least one first heat exchanger and at least one second heat exchanger being accommodated respectively along said air passage circuits, which heat exchangers are traversed by a fluid to be cooled, and adapted to transfer heat respectively to a first air stream and to a second air stream which converge in said air passage circuits, at said at least one main opening fan means being provided which are adapted to generate said air streams, characterized in that it comprises first means for closing said at least one first air intake and second means for closing said at least one second air intake, which can be activated selectively to interrupt at least one of said air streams.

[0014] Further characteristics and advantages of the present invention will become more apparent from the detailed description of a preferred, but not exclusive, embodiment of a cooling tower, particularly of the closed-circuit type, which is illustrated for the purposes of non-limiting example in the accompanying drawings wherein:

Figure 1 is a front elevation view of the cooling tower, according to the present invention;

Figure 2 is a side elevation view of the cooling tower shown In Figure 1;

Figures 3 and 4 are two schematic side elevation views of the cooling tower shown in the previous figures, in two operating modes.

[0015] With reference to the figures, the cooling tower, particularly of the closed-circuit type, generally designated by the reference numeral 1, comprises a hollow body 2 which is provided for example by a box-like body that has a substantially longitudinal extension along a preferred direction and is provided with at least one first air intake 3, with at least one second air intake 4 and with at least one main opening 5, so as to form a first air passage circuit and a second air passage circuit which are delimited by the internal walls of the hollow body 2 and extend, respectively, between the first air intake 3 and the main opening 5 and between the second air intake 4 and the main opening 5.

[0016] More precisely, the hollow body 2 comprises a first end portion 2a which forms the support base of the cooling tower 1 and, at its side walls, a plurality of first air intakes 3, and a second end portion 2b which forms, at its side walls and at its upper end face, respectively a plurality of second air intakes 4 and two main openings 5.

[0017] At least one first heat exchanger 6 and at least one second heat exchanger 7 are conveniently accommodated respectively along the aforementioned air passage circuits, are traversed by a fluid to be cooled, and are adapted to transfer heat, respectively, to a first air stream 8 and to a second air stream 9 which converge in the air passage circuits.

[0018] In the particular embodiment proposed, the first heat exchanger 6, which is schematically shown in the figures by a rectangle in dashed lines, is accommodated in the first end portion 2a and comprises a set of smooth tube nests which are adapted to transfer heat to the first air stream 8 during the humid climate season.

[0019] The second heat exchanger 7 is accommodated in the second end portion 2b and comprises a set of finned tube nests which are adapted to transfer heat to the second air stream 9 during the dry weather season.

[0020] Advantageously, such second heat exchanger 7 is substantially toroidal so as not to affect the first air stream 8, which passes centrally through it and bypasses it entirely.

[0021] According to the invention, there are first means 12 for closing the first air intakes 3 and second means 13 for closing the second air intakes 4 which can be activated selectively to interrupt at least one of the two air streams 8 and 9.

[0022] Advantageously, the closure means 12 and 13 are of the type with automatic activation and deactivation as a function of the difference in pressure between the internal environment of the hollow body 2 and the external environment of the hollow body 2.

[0023] The above-mentioned difference in pressure is made possible thanks to the presence, at the main openings 5, of fan means 14 adapted to generate the air streams 8 and 9.

[0024] More precisely, these fan means 14, which, for each main opening 5, comprise at least one axial fan 15 which is externally associated with the hollow body 2 at the corresponding main opening 5, are of the type with two-way operation so that, in a first operating mode thereof, the first air stream 8 is generated by the suction of air through the first air intakes 3 and exits from the hollow body 2 through the main openings 5 striking only the first heat exchanger 6 and so that, in a second operating mode of the fan means 14, the second air stream 9 is generated by the suction of air through the main openings 5 and exits from the hollow body 2 through the second air intakes 4 striking only the second heat exchanger 7.

[0025] In this way, as shown in Figures 3 and 4, the first closure means 12 can be activated by an increase in pressure within the hollow body 2 with respect to the pressure value of the external environment and can be deactivated by a reduction in pressure within the hollow body 2 with respect to the pressure value of the external environment.

[0026] In the same way, the second closure means 13 can be activated by a decrease in pressure within the hollow body 2 with respect to the pressure value of the external environment and deactivated by an increase in pressure within the hollow body 2 with respect to the pressure value of the external environment.

[0027] Advantageously, the closure means 12 and 13 comprise respectively lower and upper gates 16 and 17, which are normally closed due to the effect of the Earth's gravitational field.

[0028] In this way, in the absence of pressure differences between the internal environment of the hollow body 2 and its external environment, the gates 16 and 17 will remain closed due to their weight.

[0029] The cooling tower 1 is thus able to operate with both types of heat exchangers, by taking best advantage of the respective performance characteristics and routing the cooling fluid to be cooled, by way of an electronically controlled system, for example by way of a PLC (Programmable Logic Controller), to the exchanger considered the one performing best at the time.

[0030] In fact, the heat exchangers 6 and 7 are fed selectively by a single hydraulic system 18 so as to feed the first heat exchanger 6 if the first air stream 8 is generated and so as to feed the second heat exchanger 7 if the second air stream 9 is generated.

[0031] The temperature at which to "switch" from wet operation to dry operation and vice versa can be modified at will within the operating range of the cooling tower 1 in the two conditions.

[0032] More precisely, as shown in Figure 3, under conditions when the air has a high water content, i.e. during humid seasons, only the first heat exchanger 6 is fed and the axial fans 15 operate so as to suck air from within the hollow body 2 thus decreasing the inner pressure with respect to the external environment.

[0033] Such reduction in pressure consequently results in the opening of the lower gates 16 and in the closing of the upper gates 17, with formation of the first air stream 8 which strikes exclusively the first heat exchanger 6 so as to cool the fluid circulating therein.

[0034] Similarly, as shown in Figure 4, under conditions when the air has a low water content, i.e. during dry seasons, only the second heat exchanger 7 is fed and the axial fans 15 operate in the opposite direction with respect to the above description, so as to blow air inside the hollow body 2 thus increasing the inner pressure with respect to the external environment.

[0035] Such increase in pressure consequently results in the closing of the lower gates 16 and in the opening of the upper gates 17, with formation of the second air stream 9 which strikes exclusively the second heat exchanger 7 so as to cool the fluid circulating therein.

[0036] In practice it has been found that the cooling tower, particularly of the closed-circuit type, solves the drawbacks of the known art by being capable of operating in an extremely efficient manner and with high yields with any level of humidity in the air.

[0037] More precisely, thanks to the implementation characteristics of the cooling tower according to the invention, it is possible to take best advantage of the two types of heat exchangers with which it is provided, i.e. those with smooth tubes and those with finned tubes, under the conditions in which they work best: by evaporation in summer (hot, drier climate, reference parameter being the wet bulb air temperature) using smooth tubes, by air in winter (cold, more humid climate, reference parameter being the dry bulb air temperature) using finned tubes with a larger surface.

[0038] The invention, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

[0039] Moreover, all the details may be substituted by other, technically equivalent elements.

[0040] In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements.

[0041] The disclosures in Italian Patent Application No. MI2012A001686 from which this application claims priority are incorporated herein by reference.

[0042] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A cooling tower (1), particularly of the closed-circuit type, comprising a hollow body (2) provided with at least one first air intake (3), with at least one second air intake (4) and with at least one main opening (5), so as to form a first air passage circuit and a second air passage circuit which are delimited by the internal walls of said hollow body (2) and extend respectively between said at least one first air intake (3) and said at least one main opening (5) and between said at least one second air intake (4) and said at least one main opening (5), at least one first heat exchanger (6) and at least one second heat exchanger (7) being accommodated respectively along said air passage circuits, being traversed by a fluid to be cooled, and being adapted to transfer heat respectively to a first air stream (8) and to a second air stream (9) which converge in said air passage circuits, at said at least one main opening (5) fan means (14) being provided which are adapted to generate said air streams (8, 9), characterized in that it comprises first means (12) for closing said at least one first air intake (3) and second means (13) for closing said at least one second air intake (4), which can be activated selectively to interrupt at least one of said air streams (8, 9).

2. The cooling tower (1) according to the preceding claim, characterized in that said closure means (12, 13) are of the type with automatic activation and deactivation as a function of the difference in pressure between the internal environment of said hollow body (2) and the external environment of said hollow body (2).

3. The cooling tower (1) according to claims 1 or 2, characterized in that said fan means (14) are of the type with two-way operation, so that in a first operating mode thereof said first air stream (8) is generated by the suction of air through said at least one first air intake (3) and exits from said hollow body (2) through said at least one main opening (5), striking said at least one first heat exchanger (6), and so that in a second operating mode of said fan means said second air stream (9) is generated by the suction of air through said at least one main opening (5) and exits from said hollow body (2) through said at least one second air intake (4), striking said at least one second heat exchanger (7), said first closure means (12) being able to be activated by an increase in pressure within said hollow body (2) with respect to the pressure value of said external environment and being able to be deactivated by a reduction in pressure within said hollow body (2) with respect to the pressure value of said external environment, said second closure means (13) being able to be activated by a reduction in pressure within said hollow body (2) with respect to the pressure value of said external environment and being able to be deactivated by an increase in pressure within said hollow body (2) with respect to the pressure value of said external environment.

4. The cooling tower (1) according to one or more of the preceding claims, characterized in that said closure means (12, 13) comprise gates (16, 17) which are normally closed due to the effect of the Earth's gravitational field.

5. The cooling tower (1), according to one or more of the preceding claims, characterized in that said heat exchangers (6, 7) are fed selectively by a single hydraulic system (18) so as to feed said at least one first heat exchanger (6) if said first air stream (8) is generated and so as to feed said at least one second heat exchanger (7) if said second air stream (9) is generated.

6. The cooling tower (1) according to one or more of the preceding claims, characterized in that said hollow body (2) has a longitudinal extension along a preferred direction and comprises a first end portion (2a) which forms, at its side walls, a plurality of first air intakes (3) and a second end portion (2b) which forms, at its side walls and at its upper end face, respectively a plurality of second air intakes (4) and said at least one main opening (5), said at least one first heat exchanger (6) being accommodated in said first end portion (2a) and said at least one second heat exchanger (7) being accommodated in said second end portion (2b).

7. The cooling tower (1) according to one or more of the preceding claims, characterized in that said at least one second heat exchanger (7) is substantially toroidal so as not to affect said first air stream (8).

8. The cooling tower (1) according to one or more of the preceding claims, characterized in that said fan means (14) comprise at least one axial fan (15) which is associated externally with said hollow body (2) at said at least one main opening (5).

9. The cooling tower (1) according to one or more of the preceding claims, characterized in that said at least one first heat exchanger (6) comprises a set of smooth tube nests which are adapted to transfer heat to said first air stream (8) during the humid weather season.

10. The cooling tower (1) according to one or more of the preceding claims, characterized in that said at least one second heat exchanger (7) comprises a set of finned tube nests which are adapted to transfer heat to said second air stream (9) during the dry weather season.

Drawing