GB1576009A

GB1576009A - Packings for cooling towers biological filters

Info

Publication number: GB1576009A
Application number: GB7749/76A
Authority: GB
Original assignee: DAVENPORT ENG CO Ltd
Current assignee: DAVENPORT ENG CO Ltd
Priority date: 1976-02-27
Filing date: 1976-02-27
Publication date: 1980-10-01
Also published as: BE851853A

Description

(54) IMPROVEMENTS RELATING TO PACKING FOR COOLING TOWERS, BIOLOGICAL FILTERS (71) We, THE DAVENPORT ENGINEER ING COMPANY LIMITED, a British Company, of 72 Harris Street, Bradford, West Yorkshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to packings for water cooling and like towers such as are used for transferring heat and/or evaporation between liquids and gases. It also relates to packings for biological oxidation of organic pollutants in water-borne wastes.

The particular type of packing with which this invention is concerned, is built up from plastics packing sheets, formed to shapes which result, when a sheet is assembled face to face with another sheet or sheets, in the forming of a plurality of channels through which the liquids and gases can pass, the channels having a high specific surface area.

The sheets are arranged in the tower on edge, and they may be placed separately or they may be grouped by some mechanical arrange' meat 'before placement. Preferably, however, a number of sheets are bonded together to" form a rigid module of convenient and handleable size. The modules are visually of rectangular shape and are laid in close formation in-layers, the lowest layer lying across the beams of a supporting structure. Succeeding'layers may be turned 90 degrees with respect to the next layer underneath to improve the stability of the arrangement and also to improve 'liquid and air distribution. The supporting structure should be as open and simple as possible for reasons of economy, and to allow unrestricted flows of liquid and gas.

Unfortunately, the plastics commonly used for this purpose have poor mechanical strength properties, 'and particular at-tention must be given to the support of the' packing 'and to the provision of adequate crushing strength in the lower packing layers. Generally this results in the provision of a closely spaced support system and, particularly in the case of biological filters, to the use of increased material thickness in the lower layers.

The object of the present invention is to provide a more economical solution in which the basic advantages of the thin plastics sheet formations of modules are retained, whereas the requirements for added strength are fulfilled by the introduction of other material of superior mechanical properties.

According to one aspect of the invention therefore, there is provided a packing for a cooling tower or a biological filter having a packing supporting structure comprising spaced apart beams, said packing comprising a plurality of super imposed layers of sheets, the sheets in each layer being arranged on edges in face-to-face relationship and the sheets in at least the bottom layer comprising packing sheets of plastics material interspersed with reinforcing sheets of material different from that of the packing sheets, each of said reinforcing sheets bearing on and extending across the beams of the supporting structure and transferring part of the load of the packing to the beams. The sheets of the or a lower layer may be arranged at right angles to, and comprise more reinforcing sheets than, the sheets of the or an upper layer.

Preferably the sheets of at least the bottom layer are secured together in modular groups, each group comprising at least one reinforcing sheet.

According to a further aspect of the invention there is provided a module of sheets for incorporation into a packing for a cool ing-tower or biological filter as aforesaid, the sheets being secured together in face-toface relationship and comprising a plurality of packing sheets of plastics material and at least one reinforcing sheet of material different from that of the packing Sheets, said at-least one reinforcing sheet being capable, when bearing on and extending across spaced apart beams of a packing supporting structure, of transferring part of the load of the packing to the beams.

Preferably the reinforcing sheets extend throughout their length at least to the full depth of the adjacent packing sheets. The reinforcing sheets may be of non-plastics material and may comprise asbestos cement.

Flat sheets are preferred for maximum reinforcing effect and for minimum disturbance to the function of the plastics packing sheets. They will be of a material having superior mechanical properties to those of the packing sheets, particularly in resisting the crushing load of the super imposed layers of packing. Asbestos cement and reinforced polyester are two appropriate materials, but others may be found to be satisfactory.

Instead of using flat reinforcing sheets, they may be corrugated or of other crosssectional form to give them additional strength in edgewise compression.

When the direction of the sheets changes through 90 degrees in alternate layers, crossover points are produced by which the loading is transferred from each layer of packing, and hence via the reinforcing sheets to the final support system. The spacing of the reinforcing sheets can be reduced to provide an increased number of crossover points in the lower packing layers and to provide increased bending resistance in the bottom layer, so that the spacing apart of the supporting members may be increased. Applications and embodiments of the invention will now be described by way of example and with reference to the accompanying drawings of which: Figure 1 is a perspective view of part of a cooling tower packing system; Figure 2 is a perspective view of part of a biological filter packing system; and Figure 3 is a section (part cut-away) of a packing module.

Figure 1 illustrates a suitable arrangement for a cooling tower The reinforcing sheets 1 are placed between the modules 2 of a plurality of face-to-face packing sheets in the bottom layer 3 which receive extra support at the centre of the span, by an arrangement of dowels or rods 4 passed through the lower parts of the reinforcing sheets, directly below the modules. Thereby the reinforcing sheets serve to transfer part of the load of the packing to the beam members 5 of the supporting structure. It is essential that the components in the bottom laver be assembled tightly, in order that full lateral restraint to the reinforcing sheets is obtained. Improved stability of the construction will be obtained if the reinforcing sheets are bonded, either mechanically or with a suitable adhesive, to one or both sides of the plastics packing modules.

Each of the succeeding layers 6, 7 and 8 is arranged at 90 degrees to the layer below.

Whereas the problem in cooling towers is generally concerned with bending resistance of the packing between the supporting members, together with bearing strength at the supports, there is, in the case of biological packing, the additional problem of adequate crushing strength to resist the weight of the biological growth which develops on the packing surfaces and the weight of the water held by this growth.

Figure 2 illustrates how the compressive strength of the modules can be varied to correspond with the change of loading with depth within the packing.

In the lowest layers 100, where the load is maximum and the load-bearing beams 9 are widely spaced, the modules 11 which are typically 600 X 600 X 1200 mm in dimension, have reinforcing sheets 12 at 200 mm intervals. The next higher layer 13 in which the modules 14 are at 90 degrees to those in layer 10, is not required to bear such a great load and moreover is itself supported on the load bearing edges of the reinforcing sheets of the lowest layer 10, and it is found adequate to arrange that the spacing of the reinforcing sheets 12 is 300 mm. The next highest layer 15 comprises modules of un-reinforced modules of plastics packing sheets according to the known art.

Figure 3 shows a section of a packing module (part cut-away) such as is used in the arrangement of Figure 1. It comprises a plurality of plastics packing sheets 20, each formed with corrugations 21, the corrugations being inclined to the vertical in opposite directions in adjacent sheets. The sheets typically measure 2500 x 300 mm and the module is 300 mm thick.

At one face of the module is a reinforcing sheet 22 of which the upper edge is aligned with the upper edge of the sheets 20. The reinforcing sheet is, however, 400 mm wide and projects below the lower edge of the plastics sheet 20. The downward projection of sheet 22 is provided with a hole 23 for the passage of a supporting dowel, and it may be notched at its ends (not shown) to accommodate a supporting beam. The reinforcing sheet is a 6 mm thick flat sheet of asbestos cement, and is attached by any suitable means to the adjacent plastics packing sheet.

In other embodiments the reinforcing sheet may be of a different material, may be shaped in its horizontal cross-section and may be located within the module. The module may have different dimensions and may comprise more than one reinforcing sheet.

Whilst it is convenient to use packing sheets pre-assembled into modules for packing towers and filters, it may be desirable in some circumstances to assemble the packing and reinforcing sheets in situ. In this connection it may be useful to provide a reinforcing sheet secured to one packing sheet or between two packing sheets for use in assembling packings.

WHAT WE CLAIM IS: 1. A packing for a cooling tower or a biological filter having a packing supporting structure comprising spaced apart beams, said packing comprising a plurality of super imposed layers of sheets, the sheets in each layer being arranged on edges in face-to-face relationship and the sheets in at least the bottom layer comprising packing sheets of plastics material interspersed with reinforcing sheets of material different from that of the packing sheets, each of said reinforcing sheets bearing on and extending across the beams of the supporting structure and transferring part of the load of the packing to the beams.

2. A packing according to Claim 1 wherein the sheets of the or a lower layer are arranged at right angles to, and comprise more reinforcing sheets than, the sheets of the or an upper layer.

3. A packing according to Claim 1 or Claim 2 wherein the sheets of at least the bottom layer are secured together in modular groups, each group comprising at least one reinforcing sheet.

4. A module of sheets for incorporation into a packing for a cooling tower or biological filter according to any one of the preceding claims, the sheets being secured together in face-to-face relationship and comprising a plurality of packing sheets of plastics material and at least one reinforcing sheet of material different from that of the packing sheets, said at least one reinforcing sheet being capable, when bearing on and extending across spaced apart beams of a packing supporting structure, of transferring part of the load of the packing to the beams.

5. A packing according to any of Claims 1-3 or a module according to Claim 4 wherein the reinforcing sheets extend throughout their length at least to the full depth of the adjacent packing sheets.

6. A packing or module according to Claim 5 wherein the reinforcing sheets are of non-plastics material.

7. A packing or module according to Claim 6 wherein the reinforcing sheets are of asbestos cement.

8. A packing for a cooling tower or a biological filter having a packing supporting structure comprising spaced apart beams, substantially as described with reference to the drawings.

9. A module of sheets for incorporation into a packing according to Claim 8 substantially as described with reference to the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Whilst it is convenient to use packing sheets pre-assembled into modules for packing towers and filters, it may be desirable in some circumstances to assemble the packing and reinforcing sheets in situ. In this connection it may be useful to provide a reinforcing sheet secured to one packing sheet or between two packing sheets for use in assembling packings. WHAT WE CLAIM IS:

1. A packing for a cooling tower or a biological filter having a packing supporting structure comprising spaced apart beams, said packing comprising a plurality of super imposed layers of sheets, the sheets in each layer being arranged on edges in face-to-face relationship and the sheets in at least the bottom layer comprising packing sheets of plastics material interspersed with reinforcing sheets of material different from that of the packing sheets, each of said reinforcing sheets bearing on and extending across the beams of the supporting structure and transferring part of the load of the packing to the beams.