The present invention concerns a cell layer for cooling towers, comprising a support structure, such as supporting beams, above said cell layer and cooling cells, which are suspended from said support structure. The present invention also concerns a cell layer installation and servicing device.

Industrial plants, such as steel mills, have increasingly begun using closed-circuit water cooling systems in which the same water is circulated inside the cooling sys- tem. Water heated by a process is cooled to a suitable temperature, filtered and re- turned into a cooling pipework. Cooling of the water to a suitable temperature takes place in cooling towers. A cooling system usually comprises several cooling towers.

Said cooling towers are often located on the roofs of industrial plants.

Figure 1 shows an exemplary cross sectional representation of the structure of a cooling tower according to the prior art. A cooling tower usually has a square shell 10 with large openings 12for air flow at the bottom edges of the walls of the tower.

Above said air flow openings is a layer of cells 14, which rest on a horizontal sup- port beam structure 16. Above the cell layer is an input pipework 18, along which water that is to be cooled is piped inside the cooling tower. At the top of the cooling tower is a large fan 20, which is propelled by a motor 22. The fan causes air inside the cooling tower to circulate continuously in such a way that air flows into the lower part of the cooling tower via the air flow openings in the walls of the cooling tower, from the lower part through the layer of cells into the upper part of the cool- ing tower, and from there the air exits from the tower via an exhaust opening 30 in the roof of the tower. Grates 32, which direct the flow of air into the tower, are lo- cated at the mouth of the air flow openings. Water that is to be cooled arrives inside the tower along a supply pipework, from which the water is sprayed through nozzles 28 onto the layer of cells. Gravity causes the water to flow through the layer of cells, where the water is cooled by means of said air flowing in the opposite direction.

Water that has passed through the layer of cooling cells flows into a collecting basin 24 located at the bottom of the tower, from which the water is piped out of the tower via an output pipe 26.

Said layer of cells is comprised of cooling cells 44, which are typically in the magni- tude of 500 mm * 500 mm * 2000 mm. The individual cells consist of corrugated nets placed side by side in a vertical position and connected to each other. Many dif- ferent types of nets are used in cooling cells, said nets differing in the type of corru-

gation and in the size and shape of the mesh. Cooling cells constructed from nets are usually made of plastic.

Instead of being constructed from nets, cooling cells may be constructed from thin, corrugated plastic sheets, or foils. Said foils are placed side by side in the direction of the corrugation in a vertical position and connected to each other in such a way that vertical channels are formed inside the cell. The walls of the foils are wrinkled, which slows the flow of water through the channels. Several different types of foils may be used in cooling cells, said foils differing in material, thickness and the shape of the corrugation. Cooling cells constructed from perforated tubes are also known, in which said tubes are connected to each other to form a single component. Said tubes are connected to each other in a vertical position or stacked crosswise to each other.

Said cooling cells are stacked on top of a support beam structure so as to form a continuous layer of cells 14 covering the entire cross section of the tower. Succes- sive layers of cooling cells are stacked crosswise to each other in such a way that their joints do not coincide with each other. This to prevent the formation of vertical channels between cells along which water may flow unhindered through the layer of cells. Usually at least three layers of cooling cells are stacked on top of each other, bringing the thickness of the layer of cells to approximately 1.5 m. Large cells as tall as the entire layer of cells are also known. Naturally, such cells are stacked in only one layer.

There are several disadvantages related to said cell layers 14 for cooling towers. Be- cause the cell layer is constructed by hand from several separate cooling cells, as- sembly of the layer of cells is slow. Servicing and maintenance of the cell layers is also difficult. Water that is to be cooled contains foreign particles, such as rolling scale and humus, which stick to the inside of the cells. Due to the thickness and structure of the cell layer, it is practically impossible to wash the cell layer while it is in place, for which reason the cell layer needs to be periodically dismantled for cleaning. Naturally, the cooling tower must be shut down during cleaning, which hinders cooling system operation. Often the foreign particles cause the cooling cells to stick to each other so tightly that it is impossible to loosen them from each other without breaking them. Cells made of plastic material do not withstand mechanical handling, and they crack easily, especially in freezing temperature. For this reason often the entire cell layer must be replaced, which is very expensive. Because there is no sensible use for clogged, broken cells, they must be brought to a waste disposal site. This, of course, causes additional expense.

Patent specification US 4678615 presents a cell layer that is suspended from a sup- port structure above said cell layer by rod-like suspension means. Said rod-like sus- pension means are permanently fastened to said support structure, so the same prob- lems are encountered during installation and maintenance as with cell layers that are stacked on a bottomside support structure.

The purpose of the present invention is to introduce a structurally new type of cell layer for cooling towers as well as a cell layer installation and servicing device, which reduces the hindrances and disadvantages associated with cell layers of the prior art.

A cell layer and a cell layer installation and servicing device according to the pre- sent invention is characterized by what is presented in the inventive claims. Certain advantageous embodiments of the present invention are presented in the dependent claims.

The cell layer support structure according to the present invention is located above the cell layer, and the cell layer is suspended from the support structure. The support structure advantageously consists of horizontal support beams made of steel or rein- forced concrete, supported at their ends by pillars or the outer shell of the cooling tower. The basic idea of the present invention is that cooling cells are assembled to form cell elements, which are essentially as high as the entire cell layer, and which are simply suspended in place side by side from the support structure during installation so as to form a uniform cell layer. The cell elements are suspended from the support structure in such a manner that they are movable and removable, so if necessary, they can be removed during servicing of the cell layer In one advantageous embodiment of the present invention, transport rails are affixed to the support structure and the cell elements are fitted with rollers by which the elements are suspended from the transport rails.

In another advantageous embodiment of the present invention, the walls of the cell elements are advantageously shaped into a sinusoidal or triangular shape. This pre- vents the formation of vertical flow channels through the cell layer.

One advantage of the present invention is that it speeds up cell layer installation.

Suspension of cell elements as tall as the entire cell layer is significantly quicker than manual stacking of several layers of cell elements. This results in a savings in installation costs.

Another advantage of the present invention is that it speeds up and facilitates servic- ing and washing of the cell layer, because individual cell elements can be easily re- moved for the duration of servicing and washing. This results in a savings in servic- ing costs.

Yet another advantage of the present invention is that it increases the degree of use of the cooling system, because time spent servicing the cell layer is shortened. The cooling tower does not necessarily need to be completely shut down while the cell layer is being serviced.

Yet another advantage of the present invention is that it is environmentally friendly, because, due to its easier servicing, the usable life of the cell layer is longer and the need to renew the cooling cells decreases.

The present invention is described in detail below, with reference to the enclosed drawings, in which Figure 1 presents an exemplary cross section of a cooling tower according to the prior art, Figure 2 presents an exemplary cross section of a cell layer for a cooling tower ac- cording to the present invention, Figures 3a, 3b, 3c and 3d present exemplary cross sections of advantageous em- bodiments of cell elements of a cell layer according to the present invention, Figures 4a and 4b present exemplary cross sections of a cell layer and a cell layer installation and servicing device according to the present invention, Figure 5 presents an exemplary cross section of an advantageous embodiment of a cell layer according to the present invention, Figure 6 presents an exemplary representation of a cell layer during the cleaning phase of cell elements, and Figure 7 presents an exemplary representation of an advantageous embodiment of a cell element of a cell layer according to the present invention.

Figure 1 is explained in conjunction with the description of the prior art.

Figure 2 presents an exemplary vertical cross section of a cooling tower containing a cell layer 14 according to the present invention. In the present invention, said cell

layer is comprised of individual cell elements 36, which are essentially as tall as the entire cell layer. In the present invention, support beams 16 that support the cell layer are located above the cell layer. Said support beams, which advantageously are steel or reinforced concrete beams, essentially extend over the entire cell layer in- side the cooling tower. The support beams are supported at their ends by pillars or the outer shell 10 of the cooling tower. Transport rails 38 are fastened to the bottom surface of the support beams crosswise to the direction of said support beams. Said transport rails are advantageously metal profiles with a C-shaped cross section, which are fastened to the support beams in such a way that a slot along one side of said profile faces downward. Cell elements 36 are suspended from the transport rails in adjacent rows in such a way that they form a cell layer 14 covering the entire cross sectional area of the cooling tower.

Figures 3a and 3b present an exemplary representation of cell elements 36 according to the present invention, suspended from transport rails 38. Said cell elements are viewed from the front in figure 3a and from the side in figure 3b. In figure 3b the transport rail 38 is presented as a partial cross sectional view. The cell elements comprise a lower support 40, an upper support 42 and a cooling cell 44 in between.

The cooling cell is constructed from known corrugated net-like sheets or corrugated foils, a suitable number of which are placed side by side or on top of each other and fastened to each other to form one bale-like component. The material of the nets or foils of the cooling cell may be plastic, a composite material or advantageously metal. In one advantageous embodiment of the present invention the cooling cell is constructed of net-like sheets made by cutting and stretching metal sheets. Said metal net is advantageously made of galvanized, stainless or acid-resistant steel.

Said net may also be made of copper or aluminum, for example. A net made from metal material is significantly more durable than a net made from plastic material, so said metal net is suitable for an application where the cell layer needs to be cleaned often and applications where installation and/or servicing needs to be done in freezing temperatures. The upper support and lower support are advantageously sheet-like or stiff net-like components containing holes that allow water to flow through them. Two rod-like vertical means of suspension 46, which pass through the cell element, are fastened at their first end to the lower support 40. Said means of suspension are advantageously metal rods or cables.

Roller assemblies 48 comprised of four rollers are fastened to the second end of said means of suspension. Said roller assembly is advantageously the type of roller as- sembly commonly used on metal sliding doors, where the body of the roller assem-

bly is fitted with four nylon-surfaced rollers equipped with permanently lubricated ball bearings. Said roller assembly is placed inside a transport rail in such a way that the rollers rest on the horizontal surfaces 50 of the transport rail and the means of suspension 46 passes through a slot 52 between said horizontal surfaces. The size of the roller assembly allows it to fit inside the support rail 38 and move inside the rail.

The roller assembly allows a cell element fastened to the transport rail to be moved by pushing or pulling, whereby said cell element moves along the rail to a desired position. The number of means of suspension used in a cell element depends on the size and weight of said element. Advantageously there are at least two means of suspension with roller assemblies affixed to their ends for each cell element.

Said cell elements are as tall as a complete cell layer 14, advantageously 1.5-2 me- ters. The width and length of the cell elements may be suitably chosen according to the size of the cooling tower or circumstances related to work and installation. Ad- vantageously the width of the elements is in the magnitude of 0.3-0.5 meters, and the length is in the magnitude of 1.5-2.5 meters. The side walls of the cell ele- ments are formed into a triangular shape. The shape of the walls of the cell elements is essentially the same in all the elements, so no significant gap is left between ele- ments that are placed side by side.

Figures 3c and 3d present certain advantageous embodiments of a cell element ac- cording to the present invention. In figure 3c the surface of the side walls of the element are straight, but they are skewed with respect to the vertical direction. In figure 3d the side walls of the element are sinusoidal. The shape of the side walls can be suitably chosen; it is only essential that a vertical channel is not formed be- tween adjacent cell elements that would allow cooling water to flow unhindered through the cell layer. The shape of the walls of cell elements located at the edge of the cell layer can be straight to allow them to fit snugly against the wall of the outer shell of the cooling tower. Small overhangs may also be installed on the walls of the cooling tower to guide water that is being cooled away from the edge of the cell layer. In that case the gap between the cell elements at the edge of the cell layer and the wall of the cooling tower does not need to be closed throughout, in which case all the elements of the cell layer can be of the same shape. Using identically shaped cell elements allows free placement of the cell elements in any position in the cell layer and allows the position of individual elements to be changed.

Figures 4a and 4b present exemplary cross sections of a cooling tower equipped with a cell layer 14 according to the present invention and an installation and servic- ing device 51 according to the present invention. Said device is located on the out-

side of the cooling tower and used to install and service the cell layer. Figure 4a pre- sents a vertical cross section of a cooling tower and figure 4b presents a horizontal cross section of a cooling tower viewed from section A-A. Installation of a cell layer according to the present invention is started at the edge of the cell layer by first in- stalling cell elements 36 onto a first transport rail 38 located next to the outer shell 10. The cell elements are installed simply by pushing them into place from the end of the transport rail in such a way that the roller assemblies 48 of the elements are positioned inside the transport rail. When the cell elements of said first transport rail have been installed, the elements of the next rail are installed, and this procedure is repeated until all the elements of the cell layer are installed. The elements may also be installed in a different order. For example, installation may be started at the cen- termost rails and continued toward both edges, or installation may be started at both edges at the same time.

An installation and servicing device 51 for installing and servicing cell elements is located on one side of the cooling tower. The device includes a trough-like drainage basin 54 resting on a base, such as the roof of an industrial plant, and a support framework 56 constructed of horizontal beams and vertical pillars. Said drainage basin advantageously is a construction component built on site from reinforced con- crete. Said drainage basin may be a separate component or advantageously it may be a part of the cooling tower's collecting basin 24. Service rails 58 oriented in the lon- gitudinal direction of the drainage basin and essentially of the same length as said drainage basin, are fastened to the support framework. Said service rails are advan- tageously made of the same metal profile as the transport rails 38. One or several service carriages 60, which are movable in the direction of the service rails, are fas- tened to the service rails. Said service carriages, which are short rail-like compo- nents slightly longer than a cell element, are fastened to the service rails by means of a sliding fastening mechanism. Advantageously the service carriages are suspended from the service rails by means of roller assemblies 68. The service carriages can be moved along the service rails to a desired position above the drainage basin.

In one advantageous embodiment of the installation and servicing device the service carriage 60 includes a winch 62 with which the carriage can be lowered to allow a cell element 36 to be fastened to the service carriage. The winch includes an axle 63 fitted at one end to the service carriage by means of bearings. Cables 61 are wound around the axle, with the first ends of the cables fastened to the axle and the second ends fastened to the roller assemblies 68. As the axle rotates, the cable is wound

around the axle, raising the service carriage. Correspondingly, rotating the axle in the opposite direction lowers the carriage.

When cell elements 36 are being installed, the service carriage 60 is lowered by means of the winch 62 to a suitable working height and a cell element is fastened to the service carriage. Thereafter the service carriage is raised to the level of the transport rails 38 and moved as accurately as possible in line with the end of a transport rail. The cell element can now be installed in place simply by pushing or pulling it, whereupon it slides by means of the wheel assembly 48 from the service carriage to the transport rail. The installation and servicing device shown in figures 4a and 4b is only on one side of the cooling tower, but naturally such a device can be constructed on both sides of the tower. If the cooling system consists of several cooling towers, the installation and servicing device can be advantageously located between adjacent cooling towers. In that case the same device can be used to install and service the cell elements of both towers.

The wall of the outer shell 10 of the cooling tower situated against the installation and servicing device 51 contains sliding doors 53 at the location of the cell layer 14, which are opened during installation and servicing. It is not necessary to open the entire wall at once, but rather the sliding doors can be opened just at the place where cell elements are being installed or serviced. The wall of the cooling tower does not necessarily require sliding doors, but instead the wall can be constructed in such a way that it is easy to dismantle. In that case the wall is opened for servicing by dis- mantling sufficiently large openings in the facing and then closing the openings af- ter the servicing of the layer is completed.

The same principle is used in servicing and cleaning the cell layer of the cooling tower as is used in installing the cell layer. During cleaning, the wall or sliding doors 53 of the outer shell of the cooling tower are opened and the cell elements 36 are transferred from the transport rails 38 to the service carriage 60 over the drain- age basin. The cell elements are washed with, for example, a pressurized washer while they are suspended over the drainage basin, after which they are transferred back inside the cooling tower. Dirty waste water and particles produced when wash- ing the elements drip into the drainage basin 54. Said particles can be easily re- moved from the drainage basin to prevent them from reentering the cooling water circulation.

Figure 5 presents an exemplary representation of an advantageous embodiment of a cell layer 14 according to the present invention. The cell elements can be cleaned

one at a time or several elements can be cleaned at once. In the advantageous em- bodiment of the present invention presented in figure 5, there is an"extra"empty transport rail 38 at the edge of the cell layer. Cleaning of cell elements 36 is started from the second transport rail next to said first empty transport rail, one cell element at a time. After cleaning, each celL element is transferred to the first transport rail.

When the cell elements of the second transport rail have been cleaned, the elements of the third rail are cleaned next, after which they are transferred to the empty sec- ond transport rail. This procedure is repeated until all the elements of the cell layer have been cleaned and the empty transport rail has thus"migrated"to the opposite edge of the cell layer. Only one service carriage is needed when cell elements are cleaned one at a time. Hinged overhangs 66 fastened to the outer shell 10 at the edges of the cell layer are lowered to cover the empty transport rails. Said overhangs prevent water that is being cooled from flowing through the cell layer 14 at the loca- tion of the empty transport rail.

Figure 6 presents an exemplary representation of another advantageous embodiment of the present invention. In this embodiment the installation and servicing device in- cludes several service carriages 60, and all the elements of one transport rail 38 are transferred at one time onto service carriages over the drainage basin 54 for clean- ing. A movable overhang 64 can be installed over the empty transport rail to prevent the water that is being cooled from flowing through the cell layer at the location of the cell elements that are being serviced. The movable overhang is a sheet-like component slightly wider than an individual cell element and with a downward slope toward its edges. The movable overhang includes a roller assembly 70 by which it is suspended from the transport rail. After cleaning, the overhang is re- moved and the cell elements are moved back into their own place. All the cell ele- ments are cleaned in like manner. Due to the movable overhang, cooling tower op- eration does not necessarily need to be shut down completely while cell elements are being cleaned. Naturally, if the cooling tower is shut down during servicing, movable overhangs are not needed.

After cleaning, a cell element can either be returned to the transport rail in its origi- nal position or its position in the cell layer can be changed. This change can be done, for example, if it is noticed that elements in a certain position in the cell layer become clogged or broken more quickly than average. Individual broken cell ele- ments can easily be replaced with new ones in conjunction with cell layer servicing and cleaning.

Figure 7 presents an exemplary representation of yet another advantageous em- bodiment of cell elements of a cell layer according to the present invention. In this embodiment the cell elements do not include a rod-like means of suspension 46 or a lower support 40, but instead a cooling cell 44 is suspended directly from a sheet- like upper support 42. The cooling cell is advantageously constructed from nets or foils placed side by side and fastened by one edge to the upper support. The nets or foils do not necessarily need to be fastened to each other. The nets or foils are formed into a sinusoidal or other shape to produce a desired non-vertical shape in the side walls of the cell element.

Certain advantageous embodiments of a cell layer and a cell layer installation and servicing device according to the present invention are described above. The present invention is not limited to the embodiments described above, but rather the inven- tive idea can be applied in a number of ways to the extent allowed by the enclosed claims.