WO2010000212A1 - Hybrid cooling tower - Google Patents

Abstract

The invention relates to a hybrid cooling tower of a hybrid cooling plant having a mixing chamber (7) with at least one mixing fixture (10) which is in the form of a truncated pyramid and which projects transversely into an ascending first air flow (F), which mixing fixture (10) supplies a second air flow (T) to the first air flow (F) and completely or predominantly has an open trapezoidal underside (11) and an open rectangular outlet side. An opening is arranged in at least one trapezoidal side wall of the mixing fixture (10). Vapor-free operation, but in particular low-vapor operation, of a hybrid cooling plant (1) can be enabled in this way.

Description

 Hybrid cooling tower

The invention relates to a hybrid cooling tower of a hybrid cooling system according to the features in the preamble of claim 1.

From DE 196 11 627 A1 a generic hybrid cooling tower is known. Such a hybrid cooling tower or hybrid cell or cell cooling tower, together with other identical "cells" usually part of a larger hybrid cooling system and combines a wet / dry cooling of water vapor. Hybrid cooling systems are used when pure wet cooling is out of the question. Reasons for this can be annoyances caused by visible swaths.

A hybrid cooling tower can be divided into four sections: wet section, dry section, mixing chamber and machine system. The machine system is located above the mixing chamber and comprises as an essential element a fan with associated drive unit. The fan draws cooling air from below into the mixing chamber. Below the mixing chamber is the wet end with a water distribution system. From below, therefore, a "wet" air stream is sucked. Side of the mixing chamber are heat exchangers, in particular finned tube bundles, through which the cooling water is passed. From this area, "dry" air is thus sucked in, which mixes in the mixing chamber with the "wet" air stream to form a vapor-free as possible exhaust air mixture.

The basic goal when designing a hybrid cooling tower is to minimize the amount of material used and minimize pressure loss the fan sizing to achieve the most effective, ie optimum mixing of the moist air with the dry air. Steam-free working hybrid or Zeilkühltürme, can be achieved according to previous knowledge only by means of additional fans for the dry part.

The Applicant has made numerous investigations on a typical design of a so-called cell or mixing chamber with the dimensions 15 m x 13 m. Both at the lower inlet for the moist air and at the inlet for the dry air, uniform, i. constant speed profiles, since studies have shown that this is realistic. Starting from DE 196 11 627 A1 it has been found that truncated pyramidal mixed installations in which a roof surface of the mixing installations is cross-slotted, ie has permanent openings, does not always lead to optimum mixing results. This is the case in particular in the case of the so-called back-to-back arrangement, in which mixing installations can protrude into a mixing chamber only from one side wall, since the adjacent mixing chambers are to some extent back-to-back.

The invention is thus based on the object of further developing a hybrid cooling tower in such a way that the most trouble-free operation is achieved, both in individual operation and in a back-to-back arrangement.

This object is achieved in the hybrid cooling tower according to the invention by the features of patent claim 1.

The invention is further developed by the features of the subclaims in an advantageous manner.

Essential in the hybrid cooling tower according to the invention is that at least one of the hitherto closed side walls of the mixing installation is provided with at least one opening. Experiments have shown that openings in the roof surface of the mixing installation to a very rapid and strong outflow the second, dry air flow, which can lead to an unsatisfactory mixing and thus undesirable formation of steam. In principle, although the opening of the roof surface leads to the reduction of pressure losses within the mixing chamber, however, the distance between the roof surface and the upper outlet end of the hybrid cooling system, ie the upper edge of a ring surrounding the fan (diffuser), too low for intensive mixing with that of below coming first air flow, which flows mainly laterally past the mixing installation. This leads to the undesirable formation of steam. This effect occurs essentially independently of the position of the opening in the roof surface, so that a swath-free operation is possible only under special climatic conditions, especially in summer operation. However, it has surprisingly been found that a low-swath and even a swath-free operation is possible if an opening is arranged in at least one of the trapezoidal side walls of the mixer assembly. The arrangement, shape and size of the opening has a decisive influence on the swath formation and can be determined exactly for each application.

An "opening" in the sense of the invention is any air-permeable area in the side wall, regardless of the size, shape or position. A "sidewall" is that part of the mixer which is bounded by the top, bottom and inlet and outlet sides. The side wall can be porous and therefore have a multiplicity of small openings / pores or even have only a single or even a larger opening.

It is considered to be very advantageous if the at least one opening extends to the bottom. In a sense, this is a groove in the side wall which is open towards the underside of the mixing installation.

Furthermore, it has proved to be advantageous if at least one opening extends to the outlet side. Such an opening could to a certain extent be referred to as a horizontal slot. However, it is considered favorable if the opening not only to the exit side, but at the same time to the bottom - A -

is open. This does not mean that the entire side wall of the mixing installation should be open. Only a portion of the side wall, which is smaller than the side wall should be recessed at the outlet end of the mixing installation. This may for example also be an opening which has a lower height than the side wall. In principle, however, it is also conceivable that the opening is just as high as the side wall, i. extends from the bottom to the roof surface. In other words, at least one side wall can be made shorter than the roof surface.

In an advantageous development, a first opening is arranged at a distance from the inlet side which is greater than 60% of the length of the mixed installation measured between inlet side and outlet side. This first opening is thus preferably closer to the exit end than to the entry sides of the mixing installation.

In addition, a second opening of smaller cross section may be arranged in the side wall opposite the first opening. This second opening should be at least a factor of 2 smaller than the cross section of the first opening. The position of the second opening also has a great influence on the swathing.

Either the first opening and the second opening may be located immediately opposite, i. are in equal distance ranges from the entrance side. Alternatively, the second opening may be staggered to the first opening, i. that the openings are not directly opposite, so that their distance ranges, as measured from the inlet side, do not overlap.

In the hybrid cooling tower according to the invention, it should be noted that in a back-to-back arrangement, only one chamber wall of the mixing chamber can be provided with mixing internals. In this case, it is considered expedient according to a second embodiment, if two mixing internals are arranged side by side on a chamber wall of the mixing chamber, which extend over the entire width of the chamber wall. The first one lateral opening of the mixing internals is to be arranged in the adjacent side walls of the mixing internals, wherein the second opening is arranged in the outer side walls. The larger openings are therefore located in the central region of the mixing chamber and lead here to an intensive mixing of the first and second air flow. Only a smaller partial air flow is discharged via the respective outer side walls via the second openings. This design of the mixing internals is a very good compromise between freedom from swath and pressure losses, especially in a back-to-back arrangement of the mixing chambers.

In addition, in the adjacent sidewalls, i. the inner side walls with the first larger opening each have a further opening, the so-called third opening are arranged, the cross-sectional area, however, should be smaller by a factor of 2 - 10 than the cross-sectional area of the first opening. The first opening is closer to the exit side than this third opening.

The swathing is not only dependent on the location, size and geometry of the openings, but also on the other geometry of the truncated pyramid-shaped Mischeinbaus and in particular on the thermodynamic boundary conditions, such. As the speed and the pulse current density of the fluids. It is considered expedient if the height of the pyramid circumscribing the flow channel of the truncated pyramid-shaped mixing installation corresponds to the distance of the opposite chamber walls of the mixing chamber. So that the pressure losses do not become too high, the length of the mixed installation measured in the horizontal direction should correspond within a range of 55% -85% of the height of the pyramid, which is also measured in the horizontal direction. In other words, the mixing installation extends over 55% - 85% of the length of the mixing chamber, since the height of the pyramid should correspond to the distance of the chamber walls of the mixing chamber. Although the installation of two mixing internals leads to a higher manufacturing and material costs, than the installation of a single mixing installation, however, brings a single mixed installation with closed roof surface relatively high pressure losses, so that when using only a single mixing installation, this only about 55% - 75 % of the height of the mixing installation descriptive pyramid should extend. The tendency here is to the lower limits. In the case of two mixed installations arranged next to each other, their length should be within a range of 70% - 80% of the height of the circumscribing pyramid.

With porous sidewalls, up to 50% of the area of the sidewall may be formed by openings / pores. The openings / pores may be distributed homogeneously or inhomogeneously.

It is also possible that the bottom is not fully open, but closed at the entrance to about 1/4 - 1/3, i. air-impermeable to move the mixing with the moist air further into the indirect area of the mixing chamber. The underside should predominantly, i. be mostly open.

The hybrid cooling tower according to the invention makes it possible, even at low outside temperatures, to achieve low-loss operation and, with optimum design, also to operate without swirling, without the need for additional fans in the lateral area of the mixing chamber. In summer mode, i. At higher outside temperatures, a much lower formation of steam is generally to be expected than in winter operation. In order to reduce the pressure losses in summer operation, it can be provided in the development according to the invention that at least one closable roof opening is incorporated into the trapezoidal roof surface. Theoretically, it is even possible to open the roof surface completely or at least in very large parts at very high outside temperatures in order to minimize the pressure losses.

In principle, it is also possible within the scope of the invention to adapt the openings in the side walls, ie in the form and / or position and / or size change, by being arranged on the openings adjustable elements. The adaptation can preferably take place during operation.

The invention will be explained in more detail with reference to schematic embodiments shown in the drawings. Show it:

Figure 1 shows a schematic, vertical cross-section of a hybrid cooling tower with a truncated pyramid mixing installation;

FIGS. 2a-d show a first embodiment of two mixing internals;

FIGS. 3a-d show a further embodiment of two mixing internals and FIGS

FIGS. 4a-d show a third embodiment of a mixing installation.

Figure 1 shows a hybrid cooling tower 1, in which hot water is cooled on the one hand in direct exchange and on the other hand in the indirect exchange with cooling air K. The rectangularly formed in horizontal cross section hybrid cooling tower 1 has in a lower height range lateral inlet openings 2, via which cooling air K enters the hybrid cooling tower 1. The cooling air K is sucked in via a fan 3, which is arranged in the upper region of the hybrid cooling tower 1 below a diffuser 4. The passing through the inlet opening 2 in the hybrid cooling tower 1 cooling air K flows through wet cooling elements 5, which are incorporated in a horizontal plane in the hybrid cooling tower 1. In the area of the wet cooling elements 5, the cooling air K absorbs moisture through direct contact with the water to be cooled, so that a moist first air flow F rises upwards from the wet cooling elements 5. In a height range above the wet cooling elements 5, a further inlet opening 8 for cooling air K is provided. On the outside of the inlet opening 8 dry cooling elements 9 are arranged in a vertical configuration. The dry air stream T emerging from the dry cooling elements 9 is channeled through mixing internals 10 and introduced into the central region of the mixing chamber 7 above the wet cooling elements 5. The mixing installation 10 is configured in the shape of a truncated pyramid, as will be explained below with reference to FIGS. 2 to 4. The Mischeinbau 10 is in this embodiment, on its underside 11 completely open, so that the first, humid air flow F can already mix within the mixing fitting 10 with the dry air flow T. The mixed air streams exit through the diffuser 4 from the hybrid cooling system 1.

It can be seen that a pyramid 12 circumscribing the truncated pyramidal mixing installation 10 has a height which corresponds to the distance between the chamber wall 6 which is the right in the image plane and the chamber wall 13 which is left in the image plane. The mixer 10 itself has a shorter length, which is in a range of 55% - 85% of the height of the pyramid 12 and the distance of the chamber walls 6, 13.

FIG. 2 shows a first embodiment of truncated pyramid-shaped mixing internals 14a, 14b, which are arranged next to one another in the mixing chamber /. The mixing internals 14a and 14b have the same width, length and height. Their side walls 18 are, however, configured in mirror image. The mixer 14a has due to the truncated pyramidal configuration a closed trapezoidal roof surface 15, an open, rectangular exit side 16 and an open, trapezoidal bottom 17. This also applies to the mixing installation 14b. However, each trapezoidal outer side walls 18 and inner, facing side walls 19 are provided with openings. The side walls 19 have an opening 20 at the exit end, which is open to both the outlet side 16 and the bottom 17. In this embodiment, the mixing internals 14a, 14b have a total length L of 10.5 m at a height H of the relevant for the cross-section pyramid 12 of 15 m (Figure 2b). In FIG. 2c, it can be seen that the outlet-side opening 20 in the inner side wall 19 is located in the front quarter of the mixing insert 14a, 14b. Specifically, in this embodiment, it starts at a distance A of 8 m, measured from the inlet side 21 of the mixing internals 14a, 14b. In the opposite, outer side wall 18 is another opening 22, which may be referred to as a second opening. In this embodiment, the second opening 22 at a distance A1 of 7 m, measured from the inlet side 21 and terminates at a distance A2 of 8 m. The openings 20, 22 are thus not directly opposite, but are arranged offset to one another. The second opening 22 is also open to the underside 17 of the mixing fixtures 14a, 14b and extends to the roof surface 15. However, the cross-sectional area of the second opening 22 is substantially smaller than the cross-sectional area of the first opening 20 so that clear from the second opening 22 less air exits than from the first opening 20. On the inlet side 21, the inlet opening is 3.40 m high and 5.90 m wide. The cross section is reduced to the exit side 16 to about 1.77 m in width and about 1 m in height. There are exactly two mixing internals 14a, 14b arranged on a mixing chamber wall. The mixing internals 14a, 14b extend over the entire width of a mixing chamber wall.

The embodiment of Figure 3 differs from that of Figure 2 in terms of the location, arrangement and number of openings. For components that remain the same, the reference numbers already introduced in FIGS. 1 and 2 are used.

The illustrated mixing internals 23a, 23b have, in addition to the first opening 20 in the inner side wall 19, a further opening 24, which may be referred to as a third opening with respect to the respective mixing installation 23a, 23b. This third opening 24 is also configured slit-shaped, as is the second opening 22 in the side wall 18. In order to enable low-soreness operation, the openings 20, 22, 24 have been positioned relative to one another in a particular manner. The exit-side opening 20 is configured the same as in the embodiment of Figure 2, but has a greater width B1 of, in this embodiment, 4 m. In this case, however, it should also be considered that the mixing internals 23a, 23b are significantly longer than in the embodiment of FIG. 2. Assuming a pyramid height H of 15 m, the mixing structures 23a, 23b have a length L of 12 m. They thus extend over 80% of the height H of the pyramid 12. The second opening 22 has been moved further towards the exit side 16 in comparison with the first embodiment and is now directly opposite the first opening 20. The second opening 22 has a width B2 of 1.5 m and is located at a distance A2 of 8.50 m, measured from the inlet side 21. The third opening 24 is again significantly narrower with a width B3 of 0.50 m. It is located at a distance A3 of 5 m measured from the inlet side 21st

The embodiment of Figure 4 provides for only a single mixing insert 25 instead of two juxtaposed mixed internals. This is twice as wide for it. Specifically, the mixing installation 25 is provided for installation in a mixing chamber 7, in which the height H of the pyramid 12 is again 15 m, corresponding to the distance of the mixing chamber walls. The width of such a mixing chamber 7 is 13 m as large as the width of the illustrated mixing installation 25. In this type of mixing installation 25, it is not necessary to make the side walls 18, 19 different. It is therefore in each side wall 18, 19 only one opening 20 is provided. The opening 20 is open to the bottom 17 of the mixing fitting 25 and extends slit-shaped to the roof surface 15. It is located at a distance A4 of 8 m, measured from the inlet side 21 and has a width of 2 m, so that they in one Distance A5 of 10 m, measured from the inlet side 21 ends.

In this embodiment, the Mischeinbau 25 has a length L of 10.50 m according to the embodiment of Figure 1, which corresponds to a value of 70% of the height H of the pyramid 12.

By way of example, a closable roof opening 26 is arranged in the trapezoidal roof surface 15 of the mixed installation 25. The roof opening 26 is shown in dashed line and can be opened during summer operation to reduce the pressure loss. In winter operation, the roof opening 26 is at least partially, but preferably completely closed. The roof opening 26 shown is pure in size and arrangement to understand by way of example. In principle, further roof openings in the roof surface 15 can be provided. In principle, the invention also does not exclude the possibility of opening the entire roof surface 15 in summer operation, for example by means of a Venetian blind arrangement. The embodiments of the roof opening 26 also apply to the embodiments of Figures 2 and 3.

REFERENCE CHARACTERS:

1 - hybrid cooling tower

2 - inlet opening 3 - fan

4 - diffuser

5 - wet cooling element

6 - chamber wall 7 - mixing chamber

8 - entrance opening

9 - Dry cooling element 10 - Mixed installation

11 - Bottom

12 - pyramid

13 - chamber wall 14a - mixed installation 14b - mixed installation

15 - roof area

16 - Exit side 17 - Bottom

18 - side wall

19 - side wall

20 - first opening

21 - Entrance side

22 - second opening 23a - mixed installation 23b - mixed installation

24 - third opening

25 - mixed installation

26 - roof opening A1 distance

A2 distance

A3 distance

A4 distance

A5 distance

B1 - distance

B2 distance

B3 distance

H-height v.12

L - length

K- cooling air

F - first airflow (moist air)

T - second airflow (dry air)

Claims

claims A hybrid cooling tower of a hybrid cooling system, comprising a mixing chamber (7) with at least one in a rising first air stream (F) transversely projecting truncated pyramidal Mischeinbau (10, 14a, 14b, 23a, 23b, 25), which supplies the first air flow, a second air flow and which has a completely or predominantly open trapezoidal underside (11, 17) and an open rectangular outlet side (16), characterized in that in at least one trapezoidal side wall (18, 19) of the mixing insert (10, 14a, 14b, 23a, 23b, 25) at least one opening (20, 22, 24) is arranged. 2. hybrid cooling tower according to claim 1, characterized in that extending the at least one opening (20, 22, 24) to the bottom (17). 3. hybrid cooling tower according to claim 1 or 2, characterized in that extending the at least one opening (20) to the outlet side (16). 4. hybrid cooling tower according to one of claims 1 to 3, characterized in that a first opening (20) at a distance from the inlet side (21) is arranged, which is greater than 60% of the inlet side (21) and outlet side (16) measured length (L) of the mixing fixture (10, 14a, 14b, 23a, 23b, 25). 5. hybrid cooling tower according to claim 4, characterized in that a second opening (22) of smaller cross-section in the first opening (20) opposite side wall (18) is arranged. 6. hybrid cooling tower according to claim 5, characterized in that the cross section of the second opening (22) is smaller by at least a factor of 2 than the cross section of the first opening (20). 7. hybrid cooling tower according to claim 5 or 6, characterized in that the first opening (20) and second opening (22) are arranged directly opposite one another. 8. hybrid cooling tower according to claim 5 or 6, characterized in that the second opening (22) to the first opening (20) is arranged offset. 9. hybrid cooling tower according to one of claims 1 to 8, characterized in that on a chamber wall (6) of the mixing chamber (7) two mixing internals (10, 14 a, 14 b, 23 a, 23 b) are arranged side by side, wherein the first opening (20) in the adjacent side walls (19) of the mixing internals (10, 14a, 14b, 23a, 23b) and the second opening (22) in the outer side walls (18). 10. hybrid cooling tower according to claim 9, characterized in that in each of the adjacent side walls (19) at least one third opening (24) is arranged. 11. hybrid cooling tower according to claim 10, characterized in that the cross-sectional area of the third opening (24) by a factor of 2 to 10 is smaller than the cross-sectional area of the first opening (20). 12. hybrid cooling tower according to one of claims 1 to 11, characterized in that the height (H) of the flow cross-section of the truncated pyramidal mixing insert (10, 14 a, 14 b, 23 a, 23 b) circumscribing pyramid (12) the distance of opposite chamber walls (6, 13 ) corresponds to the mixing chamber (7). 13. hybrid cooling tower according to claim 12, characterized in that the length (L) of the mixing insert (10, 14a, 14b, 23a, 23b) in a range of 55% to 85% of the height (H) of the pyramid (12). 14. Hybrid cooling tower according to one of claims 1 to 13, characterized in that in the mixing chamber (7) a single, over the Whole width of a chamber wall (6) extending Mischeinbau (25) is arranged, whose length (L) in a range of 55% to 75% of the height (H) of the circumscribing pyramid (12). 15. hybrid cooling tower according to claim 12, characterized in that in a mixing chamber (7) with two Mischeinbauten (14a, 14b, 23a, 23b), the length (L) of the Mischeinbauten (14a, 14b, 23a, 23b) in a range of 70 % to 80% of the height (H) corresponds to the circumscribing pyramids (12). 16. hybrid cooling tower according to one of claims 1 to 14, characterized in that in a trapezoidal roof surface (15) of a Mischeinbaus (10, 14a, 14b, 23a, 23b, 25), at least one closable roof opening (26) is arranged. 17. Hybrid cooling tower according to one of claims 1 to 16, characterized in that the side wall (18, 19) is at least partially porous. 18. hybrid cooling tower according to one of claims 1 to 17, characterized in that a maximum of 50% of the side wall (18, 19) of openings (20, 22, 24) are formed.