WO2007143798A1

WO2007143798A1 - Systems and methods for conserving water, cooling tower and heat exchanger

Info

Publication number: WO2007143798A1
Application number: PCT/AU2007/000850
Authority: WO
Inventors: Richard Hunwick
Original assignee: Richard Hunwick
Priority date: 2006-06-16
Filing date: 2007-06-18
Publication date: 2007-12-21
Also published as: AU2007260596A1

Abstract

The present disclosure relates to a method and system for conserving water. The method includes implementing a water conservation arrangement to reduce the amount of water consumed by an industrial facility for the purpose of cooling. In one embodiment, the industrial facility is an electrical power generation plant employing an evaporative cooling system and the step of implementing the water conservation arrangement includes additionally installing a dry cooling system.

Description

SYSTEMS AND METHODS FOR CONSERVING WATER, COOLING TOWER

AND HEAT EXCHANGER

Field of the Invention

The present invention relates to systems and methods for conserving water, particularly but not exclusively, to systems and methods for conserving water by reducing the amount of water consumed by large scale facilities, such as electrical power generation utilities. The present invention also relates to systems and methods for implementing cooling towers utilised by industrial facilities and also to heat exchangers which may be used with such cooling towers.

Background of the Invention

In thermal power generation stations (power plants), electrical energy is produced by a heat engine which transforms a thermal energy into rotational energy using a turbine or the like. In a common class of power plants, those based on the Rankine Cycle, the thermal energy is in the form of steam which has been generated by a boiler at typically 100-200 times atmospheric pressure or even higher, and which is subsequently used to turn rotor blades of the turbine as it expands through it for producing electrical energy.

To recover the water for re-use in the boilers, the exhausting steam, when fully expanded at a pressure typically 0.1 times atmospheric or even lower, is condensed back to its liquid state using a condenser. When steam condenses, it releases its latent heat through vaporisation. For condensation to proceed, this latent heat must pass from the condensing steam to some medium capable of accepting it; typically large volumes of water circulating through tubes in a condenser. In turn, this circulating cooling water is warmed, so it in turn must also be cooled to its original temperature if it is to be returned to the condenser in a state that it may perform its heat absorbing role once again.

Evaporative cooling towers are the most commonly used cooling systems due to the effectiveness of evaporation for cooling water irrespective of the ambient temperature. These are "closed loop" systems which reject the waste heat by evaporation or a portion of the circulating water into the atmosphere. The downside to evaporative cooling, however, is that a large amount of water can be lost through evaporation. For example, a large power plant employing evaporative cooling such as the Bayswater Power Station located in New South Wales, Australia, will lose around 30,000 Mega Litres of water annually due to evaporation alone

An alternative form of evaporative cooling involves rejecting the waste heat by discharging the warmed cooling water into a large body of water such as a lake or dam. The temperature of the lake or dam is thereby increased which can have effects on the ecology of the surrounding area. This temperature rise leads to increased evaporation, the main mechanism by which the water is cooled to allow its re-use as condenser cooling water. Water losses by evaporation are overall comparable to those from an evaporative cooling tower servicing the same size power generation unit. Large body cooling is only available where the power plant is situated in proximity to a suitable large body of water.

The water consumed by such large scale facilities as power plants is significant, hi New South Wales, for example, the amount of water lost by evaporation from the State's inland power plants is equivalent to around one seventh of the Sydney metropolitan area's total water consumption. Yet New South Wales is under a great deal of pressure to come up with water conservation measures and/or additional water supplies. There are similar pressures in other Australian States and in most other countries around the world.

In New South Wales, water is distributed to large scale water consumers, such as power plants, by a water authority (a government body in the case of New South Wales) which sells "water allocations" to the large scale water consumers. Often, these allocations are taken from dams which represent the bulk of water storage supply for nearby communities, hi New South Wales at least, these water allocations are still sold at a much lower than economic price for the provision of water (in fact, much lower than the cost price for the provision of water) and therefore there has been little incentive for the power plants to reduce their water consumption.

Heat exchangers have been utilised with dry cooling towers for cooling heated water which is outputted from a condenser coupled to a power generation plant ("power plant"). In such applications, a number of heat exchanger panels may be positioned to surround the base of the "dry" cooling tower. An airflow, which is created as a result of the chimney effect, or by means of fans, is drawn through the heat exchanger panels for cooling the heated water which passes through cooling tubes positioned within the heat exchanger panels. For large cooling towers (suited for major power plants), the total surface area of the heat exchanger panels appropriate for a major power plant may be around 15,000 square meters. The heat exchanger may have around 50,000 square meters of stainless steel tubing, and a great deal more area of aluminium sheet to provide the honeycomb extended surface for heat transfer. As might be expected, the cost of manufacturing these large scale heat exchanger panels is extremely high due to the material cost and high labour content required in assembling the heat exchanger internals.

It would be advantageous if there were provided system and method embodiments for economically reducing the amount of water which is consumed by industrial plants and the like which employ evaporative cooling systems. It would also be advantageous if there was provided a more cost effective and less labour intensive form of manufacturing heat exchanger embodiments, particularly heat exchangers which are utilised by dry cooling towers.

Summary of the Invention

Li accordance with a first aspect, the present invention provides a method of conserving water, including the steps of implementing a water conservation arrangement to reduce the amount of water consumed by an industrial facility for the purposes of cooling. hi one embodiment, the industrial facility is an electrical power generation plant (power plant) normally employing an evaporative cooling system. The invention is not limited to power plants, however, and may include other industrial facilities - A - which consume water for cooling purposes, such as chemical plants etc. The step of implementing a water conservation arrangement may include additionally installing a dry cooling system. In one embodiment, the dry cooling system is installed upstream of the evaporative cooling system. In an embodiment the method comprises the further step of providing a distribution arrangement for controlling a flow of fluid to and/or between the evaporative cooling system and dry cooling system, for cooling. In an embodiment the method comprises the further step of providing a harvesting arrangement for harvesting potential energy from the fluid when one of the dry cooling system and evaporative cooling system is partially or entirely bypassed using the distribution arrangement. The harvesting arrangement may comprise a turbine coupled to a generator. The distribution arrangement may comprise at least one adjustable valve. The fluid may be circulating water outputted from a condenser which cools the power generation plant. In one embodiment, the dry cooling system has a cooling capacity which is based on a desired evaporative loss in the evaporative cooling system. In an embodiment the dry cooling system has a cooling capacity which is equal to a desired reduction in evaporative loss in the evaporative cooling system, hi an embodiment, the reduction in evaporative loss is calculated by adding cooling capacity in the form of a dry cooling system, predicting an amount of heat which would be rejected by the dry cooling system and also by the evaporative cooling system using key climate data. hi an embodiment, only the dry cooling system is operational for cooling below a predefined ambient temperature. In an embodiment, the predefined ambient temperature is dependent on at least one of a cooling capacity of the dry cooling system and cooling capacity of the evaporative cooling system. hi accordance with an embodiment the method further includes the step of determining an amount of water conserved by implementing the water conservation arrangement and selling the amount of conserved water. In an embodiment the amount of conserved water is sold to other consumers, hi an embodiment the amount of conserved water is sold to a water controlling authority, hi an embodiment, the amount of conserved water is sold to one of the other consumers or water controlling authority at an economic price, hi an embodiment, for a power generation plant not already employing an evaporative cooling system, the step of determining the amount of conserved water includes predicting the amount of water which would be consumed if the power generation plant had employed an evaporative cooling system. In an embodiment, the step of including a dry cooling system includes installing a dry cooling tower having radiators for cooling the circulating water.

In accordance with a further aspect there is provided a system for conserving water including a water conservation arrangement implemented in an industrial facility, the water conservation arrangement being in the form of a dry cooling system implemented in addition to an existing evaporative cooling system.

In an embodiment the system further comprises a distribution arrangement for controlling a flow of fluid to and/or between the dry cooling system and evaporative cooling system. In an embodiment the system may also comprise a harvesting arrangement for harvesting potential energy from the fluid when the existing evaporative cooling system is partially or entirely bypassed using the distribution arrangement. In an embodiment the harvesting arrangement comprises a turbine coupled to a generator. In an embodiment the distribution arrangement comprises at least one adjustable valve. In an embodiment the dry cooling system is a dry cooling tower. In an embodiment the dry cooling tower is one of a mechanical-draft dry cooling tower and natural-draft dry cooling tower. In an embodiment the existing evaporative cooling system is at least one of an evaporative cooling tower and a body of water. In an embodiment the industrial facility is an electrical power generation plant including a condenser and wherein the dry cooling tower, when in use, is arranged to cool water outputted from the condenser before it is cooled by the existing evaporative cooling system. In an embodiment the dry cooling system has a dry cooling capacity based on a desired evaporative loss. In an embodiment the evaporative loss is determined in accordance with the method steps of determining key climate data applying to a location of the industrial facility, selecting a desired cooling capacity of the dry cooling system, predicting an amount of heat which would be rejected by the dry cooling system and evaporative cooling system based on the key climate data and cooling capacity of the dry cooling system, and based on the amount of heat which is rejected by the evaporative cooling system determining the evaporative loss. In accordance with a further aspect there is provided a method of constructing a cooling tower comprising the steps of fabricating an outer shell of the cooling tower out of a plurality of partitions to form an outer shell of the cooling tower. In an embodiment the plurality of partitions are formed of light-weight material. In an embodiment the light-weight material is steel or aluminium. In an embodiment the outer shell is fabricated through a jacking process. In an embodiment the outer shell is fabricated top down. In an embodiment the cooling tower is a natural-draft cooling tower. In an embodiment the method comprises the further step of installing heat exchangers around a base of the outer shell. In an embodiment the outer shell is constructed of a light-weight material. In an embodiment the light-weight material is aluminium or steel, hi an embodiment the light-weight material is coated with a weather-proof coating.

In accordance with a further aspect there is provided a method of selling water which is conserved by a water conservation arrangement implemented in an industrial facility to reduce the amount of water consumed for the purpose of cooling, comprising the steps of determining an amount of water conserved by implementing the water conservation arrangement and selling the amount of conserved water.

In accordance with a further aspect there is provided a method of calculating an amount of water which is conserved by implementing a water conservation arrangement in an industrial facility, the method comprising the steps of determining key climate data applying to a location of the industrial facility, selecting a desired cooling capacity of the dry cooling system, predicting an amount of heat which would be rejected by the dry cooling system and evaporative cooling system based on the key climate data and cooling capacity of the dry cooling system, and based on the amount of heat which is rejected by the evaporative cooling system determining the evaporative loss. In an embodiment the water controlling authority may be a state water controlled authority such as, for example, the water authority of New South Wales, or an equivalent authority in any country or state.

In accordance with still a further aspect of the present invention there is provided a cooling tower comprising an outer shell supported by a space frame lattice. In an embodiment, the outer shell is formed from a plurality of partitions. In an embodiment, the outer shell is formed from metal. In an embodiment, the metal is aluminium. In an embodiment the metal is steel which has been coated with a weather- resistant coating.

In an embodiment, the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement. The support rod members may be coupled together by a coupling arrangement which may comprise a plurality of coupling elements which are arranged to receive the support rod members. In an embodiment, the coupling elements may be formed from sheet metal. In an embodiment the sheet metal is aluminium, hi an embodiment the sheet metal is steel which has been coated with a weather-resistant coating.

In a particular embodiment, the cooling tower is formed about an existing cooling tower. In one embodiment, the cooling tower concentrically surrounds the existing cooling tower. In one embodiment, the cooling tower co-axially surrounds the existing cooling tower. In an embodiment, the cooling tower is a dry cooling tower and the existing cooling tower is an evaporative cooling tower. In accordance with an embodiment, the space frame lattice may be braced to the existing cooling tower. In an embodiment, the cooling tower is arranged to cool a flow of water before it is passed to the existing cooling tower for cooling. In an embodiment, a void is located in the cooling tower for allowing air flow to the existing cooling tower. The void may extend along a base of the cooling tower.

In accordance with a further aspect there is provided a cooling arrangement for an industrial facility comprising a cooling tower which is formed about an existing cooling tower, hi an embodiment, an outer shell of the cooling tower is formed from metal. The metal may be aluminium, hi an embodiment the metal is steel which has been coated with a weather-resistant coating.

In one embodiment, the cooling tower concentrically surrounds the existing cooling tower. In one embodiment, the cooling tower co-axially surrounds the existing cooling tower. In an embodiment, the cooling tower is a dry cooling tower and the existing cooling tower is an evaporative cooling tower. The cooling tower may be supported by a space frame lattice. The space frame lattice may be braced to the existing cooling tower. In an embodiment, the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement. The support rod members may be coupled together by coupling arrangements. Each coupling arrangement may comprise a plurality of coupling elements which are arranged to receive the support rod members. In an embodiment, the cooling arrangement further comprises a circulating water distribution arrangement for controlling a flow of circulating water to and/or between the towers. In an embodiment the cooling arrangement also comprises a harvesting arrangement for harvesting potential energy from the circulating water when one of the towers is partially or entirely bypassed using the circulating water distribution arrangement. In an embodiment the harvesting arrangement comprises a turbine coupled to a generator. In an embodiment the circulating water distribution arrangement comprises at least one adjustable valve. In an embodiment the cooling tower is arranged to cool a flow of water before it is passed to the existing cooling tower for cooling. In an embodiment, a void is located in the cooling tower for allowing air flow to the existing cooling tower. The void may extend along a base of the cooling tower.

In accordance with a further aspect, there is provided an industrial facility incorporating a water conservation arrangement to reduce the amount of water consumed by an industrial facility for the purpose of cooling, the water conservation arrangement comprising a dry cooling tower which is formed about, and upstream, of an existing cooling tower, hi an embodiment the dry cooling tower concentrically surrounds the existing cooling tower. An outer shell of the dry cooling tower may be formed from metal. The metal may be aluminium, hi an embodiment the metal is steel which has been coated with a weather-resistant coating. In an embodiment, the dry cooling tower is supported by a space frame lattice. The space frame lattice may be braced to the existing cooling tower. The space frame lattice may comprise a plurality of support rod members coupled together in a tetrahedral arrangement. The support rod members may be coupled together by coupling arrangements. In an embodiment, each coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members. In an embodiment, the cooling arrangement further comprises a circulating water distribution arrangement for controlling a flow of circulating water to and/or between the towers. In an embodiment the cooling arrangement also comprises a harvesting arrangement for harvesting potential energy from the circulating water when one of the towers is partially or entirely bypassed using the circulating water distribution arrangement. In an embodiment the harvesting arrangement comprises a turbine coupled to a generator. In an embodiment the circulating water distribution arrangement comprises at least one adjustable valve. A void may be located in the cooling tower for allowing air flow to the existing cooling tower. The void may extend along a base of the cooling tower.

In accordance with a further aspect there is provided a space frame lattice, when in use, arranged to secure a cooling tower to an existing cooling tower. The space frame lattice may comprise a plurality of support rod members coupled together in a tetrahedral arrangement. The support rod members may be coupled together by coupling arrangements. In an embodiment, each coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members. In accordance with a further aspect there is provided a coupling element arranged to couple a support rod member to a coupling arrangement within a space frame lattice, the coupling element comprising a base which is arranged to be coupled to other coupling elements within the coupling arrangement and further comprising a receiving arrangement which, when in use, extends outwardly from the base to receive the support member. The base and receiving member may be of one-piece construction formed from a piece of sheet metal. In an embodiment the sheet metal is steel which has been coated with a weather-resistant coating. In an embodiment, the base defines a generally planar triangular shape. In one embodiment, the side walls of the base are of equal length, hi an embodiment, the receiving arrangement comprises three generally rectangular elements, each rectangular element extending from a separate side wall of the base. The rectangular elements may extend outwardly from each side wall in a plane orthogonal to the base. Each rectangular element may further comprise a triangular tab extending from a distal end thereof, the triangular tabs arranged to bend inwardly to enclose a cavity which is formed as the rectangular elements extend from the base. In an embodiment the support member comprises a hollow tube having triangular ends which are arranged to either fit over the rectangular elements or within the cavity defined thereby. A securing arrangement may be provided on the receiving arrangement for securing the support member to the coupling element. hi accordance with a further aspect there is provided a coupling arrangement for coupling a plurality of support members together within a space frame lattice, the coupling arrangement comprising a plurality of coupling elements, each coupling element comprising a base which is arranged to be coupled to other coupling elements within the coupling arrangement and further comprising a receiving arrangement which, when in use, extends outwardly from the base to receive one of the support rod members, the coupling elements fixedly coupled together in a predetermined configuration. hi accordance with a further embodiment there is provided a coupling arrangement for coupling a plurality of support members together within a space frame lattice, the coupling arrangement comprising four coupling elements, each coupling element comprising a triangular base and a receiving arrangement which, when in use, extends outwardly from the base to receive one of the support rod members, the coupling elements being fixedly coupled together such that an enclosed generally tetrahedral cavity is formed by their bases. In an embodiment the coupling elements are welded together.

In accordance with a further aspect there is provided a method of constructing a cooling tower, the method including the steps of fabricating an outer shell of the cooling tower and supporting the outer shell with a space frame lattice. The outer shell may be formed from a plurality of partitions. The outer shell may be formed from metal. The metal may be aluminium, hi an embodiment the metal is steel which has been coated with a weather-resistant coating. The space frame lattice may comprise a plurality of support rod members coupled together in a tetrahedral arrangement. In an embodiment, the support rod members are coupled together by a coupling arrangement. In one embodiment, the coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members. The coupling elements may be formed from sheet metal, hi an embodiment the sheet metal is aluminium. In an embodiment, the sheet metal is malleable steel, hi one embodiment, the cooling tower is formed about an existing cooling tower. In an embodiment, the cooling tower concentrically surrounds the existing cooling tower, hi one embodiment, the cooling tower co-axially surrounds the existing cooling tower. The cooling tower may be a dry cooling tower and the existing cooling tower may be an evaporative cooling tower. The space frame lattice may be braced to the existing cooling tower, hi an embodiment, the cooling tower is arranged to cool a flow of water before it is passed to the existing cooling tower for cooling. In an embodiment, the method further comprises the step of providing a void in the cooling tower for allowing air flow to the existing cooling tower. The void may extend along a base of the cooling tower.

In accordance with a further aspect there is provided a method of constructing a cooling arrangement for an industrial facility, the method comprising the steps of forming a cooling tower about an existing cooling tower, hi an embodiment, an outer shell of the cooling tower is formed from metal. The metal may be aluminium. The cooling tower may be formed to concentrically surround the existing cooling tower, hi one embodiment, the cooling tower co-axially surrounds the existing cooling tower In an embodiment, the cooling tower is a dry cooling tower and the existing cooling tower is an evaporative cooling tower. In an embodiment the cooling tower is supported by a space frame lattice. In an embodiment the space frame lattice is braced to the existing cooling tower. In one embodiment the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement. In an embodiment, the method comprises the further step of providing a circulating water distribution arrangement for controlling a flow of circulating water to and/or between the towers. In an embodiment the method comprises the further step of providing a harvesting arrangement for harvesting potential energy from the circulating water when one of the towers is partially or entirely bypassed using the circulating water distribution arrangement, hi an embodiment the harvesting arrangement comprises a turbine coupled to a generator. In an embodiment the circulating water distribution arrangement comprises at least one adjustable valve. The method may further comprise the steps of cutting out a former from a piece of sheet metal and bending the former to produce the base and receiving means.

In accordance with a further aspect there is provided a method of manufacturing a coupling arrangement for coupling a plurality of support members together within a space frame lattice, the method comprising the steps of joining a plurality of coupling elements in accordance with the above-mentioned aspect, wherein the coupling elements are cut from a piece of sheet material.

In accordance with above-mentioned embodiments of the present invention, a cooling tower's outer shell may be constructed to surround and effectively enclose a power stations' existing natural-draft evaporative cooling tower. Embodiments of the present invention provide a light-weight rigid structure which may be erected quickly in the field either bottom up (i.e. with the use of cranes) or top-down (by using a fleet of jacks to raise the completed portion of the tower), or a combination of the two. Embodiments of the present invention apply to both concentric and stand-alone towers.

hi accordance with a further aspect of the present invention, there is provided a method of manufacturing a heat exchanger from a plurality of sheets, the method comprising the steps of forming holes in the sheets and stacking the sheets together such that the holes are in registration to provide passages for the flow of fluid for heat exchange. In an embodiment the step of forming holes comprises making slits in the sheets and stretching the sheets to expand the slits to form the holes. In an embodiment the slits are made by making cuts in the sheets. In an embodiment the method comprises the further step of drawing at least one partition which separates adjacently located holes on the sheets and further stretching the sheets to form inwardly tapered fins which extend between the adjacently located holes for heat transfer. In an embodiment the step of drawing comprises deep-drawing the partition, hi an embodiment the method comprises the further step of forming secondary holes in the sheets, such that when the sheets are stacked together the secondary holes are in registration to provide at least one secondary passage for receiving a securing device for fixedly securing the sheets together, hi an embodiment the step of forming secondary holes comprises making secondary slits in the sheets and stretching the sheets to form the secondary holes. In an embodiment the securing device is further arranged to compress the sheets. In an embodiment the securing device is one or more tie rod(s). In an embodiment an inside face of the passages is coated with a sealant to prevent leakage of fluid from between the stacked sheets. In an embodiment the sheets are metal sheets, hi an embodiment the sheets are made from deformable aluminium, copper or thermally conductive plastics. In accordance with a still further aspect there is provided a heat exchanger which is formed from a plurality of sheets which are stacked together, the sheets comprising holes such that when the sheets are stacked together the holes are in registration to form passages for the flow of fluid for heat exchange. In an embodiment the holes are formed from making slits in the sheets and stretching the sheets to form the holes, hi an embodiment the heat exchanger further comprises inwardly tapered fins which extend between the adjacently located holes on each sheet, the fins being formed by drawing at least one partition which separates the adjacently located holes on the sheets and further stretching the sheets to form inwardly tapered fins which extend between the adjacently located holes for heat transfer. In an embodiment each sheet comprises secondary holes, such that when the sheets are stacked together the secondary holes are in registration to provide a secondary passage for receiving a securing device which compresses the sheets. In an embodiment the secondary holes are formed from making secondary slits in the sheets and stretching the sheets to form the secondary holes. In an embodiment the securing device comprises one or more tie rod(s). In an embodiment an inside face of the passages is coated with a sealant to prevent leakage of fluid from between the stacked sheets. In an embodiment the sheets are metal sheets. In an embodiment the sheets are made from deformable aluminium, copper or thermally conductive plastics.

Brief Description of the Drawings

Features and advantages of the present invention will become apparent from the following description of embodiments thereof, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagram of the cooling system for the generating units at the Bayswater Power Station located in New South Wales, Australia which employs natural-draft evaporative towers for cooling;

Fig. 2 is a schematic diagram of a water conservation arrangement according to an embodiment of the present invention, which is proposed for the Bayswater Power Station depicted in Fig. 1 ;

Figs. 3(a), 3(b) & 3(c) show alternative embodiments for retro-fitting water conservation arrangements to an evaporative cooling tower-based system;

Figs. 4(a) and 4(b) show alternative embodiments for retro-fitting water conservation arrangements to a lake cooled evaporative system;

Fig. 5 is a flow diagram showing method steps for calculating the amount of water which is conserved by implementing a water conservation arrangement in an industrial facility , in accordance with an embodiment of the present invention;

Figs. 6(a) and 6(b) show a screen shot of an Excel model and Assumptions table, respectively, which may be used in accordance with an embodiment of the present invention, to calculate the evaporative loss for the Bayswater Power Station employing the water conservation apparatus of Fig. 2; and Figs. 7(a) through 7(i) depict a method of constructing a cooling tower in accordance with an embodiment of the present invention.

Fig. 8 is a schematic view of a cooling arrangement implemented for a power station employing a pre-existing evaporative tower, in accordance with an embodiment of the present invention;

Fig. 9 is a cut-away schematic diagram of a cooling arrangement in accordance with an embodiment of the present invention;

Fig. 10 is a top view of the cooling arrangement of Fig. 9; Fig. 11 is a front view of a coupling arrangement (connected to a plurality of support members) for a lattice support structure which is used to brace an outside cooling tower of the cooling arrangement to an inside cooling tower of the cooling arrangement, in accordance with an embodiment of the present invention;

Fig. 12 shows a section of sheet metal having a plurality of stamped-out sections (or formers) which form the individual coupling elements of the coupling arrangement of Fig. 11.

Fig. 13 is a top view of detached coupling elements;

Fig. 14 is a schematic view of a cooling arrangement in accordance with an alternative embodiment of the present invention. Fig. 15 is a flow diagram showing steps for manufacturing a heat exchanger in accordance with an embodiment of the present invention;

Fig. 16 is a top view of a section of sheet metal which has been slotted for forming holes, in accordance with an embodiment of the present invention;

Fig. 17 shows the sheet of Fig. 15 after being stretched to yield the holes through which water will eventually flow;

Fig. 18 shows the sheet of Fig. 16 after deep-drawing and further stretching;

Fig. 19 is a sectional view along a part of the axis E-E of Fig. 18, after a plurality of sheets have been stacked to form fluid passages, in accordance with an embodiment of the present invention.

Detailed Description of the Preferred Embodiment

In accordance with embodiments of the present invention, water savings are achieved by retro-fitting existing power stations with water conservation arrangements, in this case dry cooling systems, or building new power stations with similar water conservation arrangements. In the following description, models of actual power stations in New South Wales, Australia, are used for the purposes of illustration. It will be appreciated, however, that the present invention may be applied to any power plant relying upon evaporative cooling, and is not limited to those discussed here.

Before describing embodiments of the present invention, the "evaporative only" cooling system for the Bayswater Power Station located in New South Wales, Australia, will be described with reference to Fig. 1.

The cooling system 100 comprises a shell and tube condenser 102 for converting exhaust steam outputted from a heat engine (not shown) to liquid form. The steam is passed over circulating water tubes 104 running through the shell 106 of the condenser 102. The resulting condensate is collected in a sump 108 located at the bottom of the condenser 102. The condensate is pumped back to the heat engine via pipe 111 and condensate extraction pump 113, for converting back to steam. A cooling arrangement in the form of a natural-draft evaporative cooling tower 112 (hereinafter "evaporative tower 112") is provided to cool the water which runs through the circulating water tubes (hereinafter "circulating water") and which connects to the circulating water tubes, via pipe 110. The evaporative tower 112 has a cooling capacity of approximately 900 MegaWatts thermal (MWt) and is made from reinforced concrete. The evaporative tower 112 includes a bank of water sprays 114 which expel the circulating water through an upward flow of ambient air 116 passing through the evaporative tower 112. In the process, approximately two per cent of the circulating water is lost through evaporation to the atmosphere; while the remaining circulating water (now cooled because of the heat removed by the proportion converted to water vapour) is collected at the evaporative tower basin 118. Make-up water is added to the collected circulating water, via pipe 120, before being returned to the condenser 102. It has been determined that the Bayswater Power Station loses through evaporation to the atmosphere approximately 30 Giga litres of water annually.

Fig. 2 is a schematic illustration of a water conservation arrangement which is proposed for the Bayswater Power Plant, in accordance with an embodiment of the present invention. According to this embodiment, the water conservation arrangement is retro-fitted to the existing evaporative tower 112 and is in the form of a natural-draft dry cooling tower 202 (hereinafter "dry tower 202"). In this embodiment, the dry tower 202 is installed up-stream of the existing evaporative tower 112. In consideration of the cooling capacity of the existing evaporate tower 112 and climate data for the Bayswater region, a cooling capacity of 20 MWt/Deg C has been selected for each dry tower 202. Heat exchanger elements in the form of a radiator bank 204 employing stainless steel or other corrosion-resistant material tubing expanded into aluminium fins or sheets are connected to the circulating water tubes 104, via pipe 108. The radiator bank 204 surrounds the base of the dry tower's outer wall 206 and is arranged to reject waste heat from the circulating water by sensible heat transfer to air flowing upwardly through the dry tower 202, as a result of the chimney effect. Advantageously, the dry tower 202 is arranged to reject a substantial amount of the waste heat from the circulating water before it reaches the evaporative tower 112. Consequently, less waste heat needs to be rejected by the evaporative tower 112, which results in less water being lost through evaporation to the atmosphere and a reduction in the amount of water consumed by the industrial plant. The Applicant has found that by incorporating four dry towers 202 (one for each of the four generating units) having a total cooling plant capacity of 80 MWt/Deg C into the existing Bayswater cooling system, the amount of water which is consumed by the power plant because of evaporative losses may be reduced by approximately 18 Giga litres of water, more than halving the power plant's annual water consumption.

Figs. 3(a) and 3(b) show alternate embodiments for implementing the water conservation arrangement of Fig. 2. In Fig. 3(a), the conservation arrangement is in the form of a natural-draft dry cooling tower 302 connected up-stream of the evaporative tower 112; while in Fig. 3(b) the conservation arrangement is in the form of a mechanical-draft (or fan assisted) dry cooling tower 304. Also shown in these Figures is a distribution arrangement in the form of a pump 306 and valves Vl, V2 & V3, for controlling the distribution of circulating water to and/or between the cooling towers. The pump 306 and valves Vl to V3 may be remotely controlled to pump and distribute circulating water into the conservation arrangement 302. hi general operation, valves Vl & V2 would be open, and valve V3 would be closed, forcing all of the circulating water to pass through the dry tower before entering the evaporative tower 112. A booster pump 306 (shown in dotted outline) may be provided to boost the pressure of the circulating water if the dry tower is located a considerable distance from the evaporative tower 112, or due to site-specific characteristics affecting the flow of circulating water through the dry cooling tower's radiator bank 204. hi the described embodiment, valves Vl & V2 may each represent many valves installed in parallel. By closing individual valves in Vl and V2 while leaving the remainder of the valves open, partial bypassing of sections of the dry tower (e.g. for maintenance) may be achieved. By opening valve V3 and closing valves Vl and V2 entirely, the dry cooling tower may be bypassed altogether.

Conditions may arise, for example in cold weather, when the dry cooling capacity of the dry tower is capable of meeting most, if not all, of the total cooling load. As the cooling system is ordinarily designed to account for a 12 to 15 metres water gauge drop across the evaporative tower 112 (ie as a result of the circulating water passing through distribution headers and sprays, through the packing and into the cooled water sump), a harvesting arrangement in the form of a head-recovery turbine 316 and generator 318 may be provided to recover some of the potential energy represented by this fall (see Fig. 3(c)). When it is desired to bypass the evaporative cooling tower, Valves Vl, V2 and V4 are opened, allowing water to pass through the dry tower 302 and into the head-recovery hydraulic turbine 316 and generator 318, to generate electricity.

In an alternate embodiment (not shown), the cooling system may comprise two circulating water pumps 312 installed in parallel, each arranged to take a predetermined percentage of the total capacity, thus allowing for partial operation of the evaporative cooling tower 112. In this configuration, the system may additionally comprise two head-recovery turbines and two valves V4 (e.g. one per turbine).

Other operational alternatives may be possible with this arrangement of pumps, valves and harvesting arrangements. For example, to achieve parallel operation of the towers 302, 112, some of the valves Vl and V2 would be closed, and some of the valves V3 & V4 would be open. For example, were there to be two valves each at^'Vl, V2 and V3, it is possible to have one of each of the two valves at each of Vl, V2 and V3 open, the other closed. The system may also include two booster pumps (not shown) installed directly after valve Vl for further increasing the head-end pressure of the dry tower 302. In one configuration, one of these booster pumps would be on (the pumps associated with the valves open at Vl) and the other switched off (the pump associated with the valves closed at Vl) to allow some of the total circulating water flow to pass through the dry cooling tower 302. In general, with the arrangement of pumps, valves and head-recovery hydraulic turbines shown, it becomes possible to have 0 to 100% of the circulating water passing through either of the evaporative tower 112 and dry tower 302. Figs. 4(a) and 4(b) show the water conservation arrangements of

Figs. 3(a) and 3(b) retro-fitted to an existing lake evaporative cooling system 402.

A method of calculating the amount of water which is conserved using the water conservation arrangement proposed for the Bayswater power station (illustrated in Fig.- 2), will now be described with reference to the flow chart 500 shown in Fig. 5, model 600 shown in Fig. 6(a) and assumptions table shown in Fig. 6(b).

The first step in calculating the amount of water which is conserved by implementing the water conservation arrangement 202 (ie the dry tower 202) is to input the key climate data of the system (step 502). The key climate data is shown in column A (Fig. 6(a)) as a range of ambient temperatures which the power plant is likely to experience throughout the year. Also at step 502, the probability that each of the ambient temperatures will be exceeded is determined (based on historical data) and is shown in column B.

At step 504, the percentage time that the corresponding ambient temperature (to the degree) is experienced is calculated and input into column C. As would be expected, Column C shows that over time temperatures closer to the annual average are experienced rather than the extremes.

The next step 506 in calculating the amount of water which is conserved, involves calculating the low-pressure ("LP") turbine exhaust temperature that would occur for each ambient temperature specified were the total cooling burden to be taken by a dry cooling tower of the capacity (in MWt/Deg C) (see cell D69 of the

"Assumptions Table" shown in Fig. 6(b)). The LP turbine exhaust temperature is shown in column D and is derived by adding the ambient temperature to the Initial Temperature Difference ("ITD") (ie the difference between the ambient temperature and the temperature of the steam exhausting - under vacuum - from the LP turbine) that would be achieved with the cooling plant capacity listed in the Assumptions table. It can be seen from column D, that the LP turbine exhaust temperature becomes quite high as the ambient temperature rises. This means that the exhausting steam expansion is reduced and total power output falls which is a significant problem, given that typically power demand is highest during these periods. Therefore at step 508 the maximum desired temperature (or controlled low-pressure temperature) of the exhausting steam is determined and listed for each ambient temperature. This data is shown in Column E of the model 600. The reason why this data is not the same for each ambient temperature is because the power station operators will typically want to be able to adjust the temperature of the LP turbine exhaust to maximize output across the year while still minimising water losses through evaporation.

At step 510, the effective "temperature driving force" between the LP turbine exhaust steam and the ambient air is calculated and inputted in column F. The calculation involves subtracting the ambient temperature from the controlled low- pressure exhaust steam temperature, correcting for the condenser approach temperature which is a measure of the difference between the temperature of the condensing steam on the circulating water tubes 207 leaving the LP turbine and the warmed circulating water exiting the condenser.

Step 512 involves calculating how much (as a percentage) of the total cooling load the specified (by assumptions as listed in the Assumptions Table) dry tower 202 will take on. This data is shown in column G and is a ratio of the data shown in Column F to the dry tower ITD which is shown in the Assumptions Table. If, however, the dry tower 202 has the capacity in theory to take on more than the total cooling load (which is possible if a very large dry tower 202 is installed), an underlying algorithm will cause this column to show 100% and all of the system cooling will be performed by the dry tower 202 to minimise evaporative loss. Similarly, the percentage load taken by the evaporative tower 112 is also derived by subtracting the values in column G from 100%. This data is shown in column H.

At step 514, the safe minimum capacity of the evaporative tower 112 is determined and input in column I. A problem arises in that natural-draft evaporative towers must rej ect a minimum amount of heat if a stable natural draft of air is to be established. As mentioned above, if a large capacity dry tower were installed, the evaporative tower 112 would be turned off entirely once ambient temperatures fell below the applicable Fig. for the total cooling load to be taken by the dry tower. Clearly, this problem would not occur if a lake or mechanical-draft system were being used for evaporative cooling. In this case, the minimum evaporative tower capacity is shown as 20%.

At step 516, the proportionate evaporative tower 112 and dry tower 202 duties are calculated after this correction has been made as per columns J and K of the table 600. The model asks whether, in the absence of any restrictions on the minimum duty to be borne by the evaporative cooling tower at the ambient temperature in question, this proportion would be below this safe minimum, here assumed (as listed in the Assumptions table and also in Column I of the table 600) to be 20% of the total cooling load. If the answer is in the affirmative, a figure of 20% is inserted in column J in the table 600 for that temperature.

Step 518 involves calculating how much of the cooling duty is taken on by the dry tower 202 (see column L) and evaporative tower 112 (column M) for a particular ambient temperature. The numbers in the cells are the result of calculations involving multiplying the probability of a particular ambient temperature (column C) by the respective relative evaporative-tower and dry-tower duties (columns J & K respectively). By summing the data shown in these columns it is possible to determine the total percentage of waste heat which is rejected by the respective towers.

At step 520, the amount of waste heat in units of GigaWatts thermal (GWt) which is rejected by the dry tower 202 and evaporative tower 112 at each of the temperatures shown in Column A over the course of a year is calculated by multiplying the cooling duty of the respective towers by the amount of waste heat which is expelled into the cooling system (in this case a total of 3,463 GWt when all four units of the Bayswater Power Station are operating at their rated capacities). This data is shown in columns N and O. The sum of each column represents the proportion of total waste heat rejected by the towers 112, 202 in an average year, assuming that the power station operates at its rated capacity 100% of the time (ie has a 100% Capacity Factor - "CF") At step 522, the amount of evaporation (or in other words, the amount of water consumed by the power plant) occurring at a particular ambient temperature can be determined. This calculation involves multiplying the figure in Column O by a factor corresponding to the amount of water that would be evaporated in a cooling tower such as at Bayswater for each unit of heat energy rejected by it. This factor takes into consideration that not all heat is lost by evaporation: some (roughly 20% on average over the course of a year) is lost by direct heating of ambient air by the warm water being sprayed through it. It needs to be noted that this factor is smaller in the case of cooling by large water bodies such as at the Liddell Power Station, located in New South Wales, Australia, since there is a third mechanism by which heat may be lost from such a body in addition to evaporation and direct heating of ambient air in contact with the surface of the lake: black body radiation. Hence, it is necessary to enter the appropriate percentage figure for the proportion of heat lost by evaporation in the Assumptions Table, which is taken to be 80% for evaporative cooling towers, and 70% in the case of large bodies of water such as cooling lakes as used at Liddell Power Station (these are conservative estimates).

By summing the data in column P, it is possible to determine the total annual evaporative water loss experienced in the power plant for a specified climate and dry tower cooling capacity 202, assuming that the power station operates at is rated capacity 100% of the time (ie has a 100% Capacity Factor - "CF"). As no power station would typically operate at its rated capacity 100% of the time, the sum of the data in column P can be multiplied by an "Effective Capacity Factor" to give the expected annual evaporative loss (step 524). According to this embodiment, by implementing the water conservation arrangement the expected annual evaporative loss is calculated to be 13.9 Giga Litres, which represents an annual saving of over 19 Giga Litres (or 58%) of water, in comparison with the existing Bayswater Power Plant employing evaporative only cooling as illustrated in Fig. 1.

hi accordance with a further aspect, an embodiment of the present invention relates to a method of selling the amount of water which is conserved by implementing the water conservation arrangement. For illustrative purposes, the method will again be described with reference to the proposed water conservation arrangement for the Bayswater power plant shown in Fig. 2. hi an embodiment, the method comprises calculating the amount of water which has been conserved by implementing the water conservation arrangement and selling the amount of conserved water. Using the model 600, it was found that by implementing a water conservation arrangement in the form of a dry tower having a dry cooling capacity of 80MWt/Deg C, the total annual water consumption of the system was reduced by 19 Giga Litres. A number of different alternatives for selling the amount of conserved water will now be described.

hi one embodiment, a third party would build, own and operate the water dry tower 202. With minimal operating costs, it may be possible to produce a supply of water (ie as a result of the amount of water conserved by implementing the dry tower 202) at a price which is well below that of building a new dam, desalination plant or other water supply, for generating a comparable supply of water. According to this embodiment, the third party may pay the power plant a small amount of money for water they don't consume, or alternatively, such payments may go the other way depending on the economics of the situation and the distribution of benefits (which for the power station may be substantial as a consequence of their reduced requirements for water handling and treatment). Also, as all capital costs associated with building the dry tower 202 would be incurred by the third party, the power station would not have to outlay any of their own capital. According to this embodiment, the third party may then sell the water conserved back to the water authority (which allocates the water to the power station) for a mutually agreed amount. In one embodiment, the agreed amount (per litre of water) is less than the amount paid by the power station for the initial allocation. In an alternate embodiment, the third party may "on sell" the amount of water which is conserved to other parties, such as other industrial facilities, at a rate which is less than that charged by the water authority. Other possible contractual arrangements include the power station owning and operating the dry cooling tower, and sell surplus water to third parties, or water authorities, either government-owned or private, could own and operate the tower.

In yet another aspect an embodiment of the present invention relates to a method of constructing a cooling tower by fabricating an outer shell of the cooling tower from a light-weight material, which will hereafter be described with reference to Figs. 7(a) through 7(h). The cooling tower may be used with the water conservation arrangements described above. For example, it may form part of the dry cooling system, being in the form of a natural-draft dry cooling tower with radiator panels. According to this embodiment, the cooling tower is in the form of a natural-draft dry cooling tower and the light-weight metal is Colorbond ™ clad structural steel. Advantageously, the cooling tower may be erected by traditional construction methods employing cranes (bottom-up construction) or it may be erected "top down" in an arrangement that serves to minimise the amount of time that construction operations and personnel need to work high above ground level.

Fig. 7(a) shows one embodiment of such top-down construction. As shown, there is shown a concrete foundation 602 and jacking arrangement for fabricating an outer shell of the cooling tower. The jacking arrangement is in the form of jacking columns 604, jacking frame 607 and working frame 608. hi accordance with this embodiment, the jacking columns are 60 meters tall. A top ring 606 of the cooling tower formed of re-enforced metal is constructed at ground level surrounding the jacking frame 607. In Fig. 7(b), the top ring 606 is attached to the jacking frame 607 by wire cables 609 and jacking commences to lift the top ring 606 off the concrete foundation 602. As the top ring 606 is lifted, a circular outer shell 610 formed of the light-weight structural steel is attached and fabricated beneath. Fabrication of the outer shell 610 continues until the jacking frame 607 has reached the top of the jacking columns 604. hi Fig. 7(c) a reinforcement ring 612 is integrated into the outer shell 610 to take its weight via supports (not shown) to the ground. Once the weight has been taken by the supports, the jacking frame is detached from the top ring 606 and reattached, at ground level, to the reinforcement ring 612 which now becomes the new "lifting point" (see Fig. 7(d)). The jacking frame 607 is raised as before and fabrication of the outer shell 610 continues, hi Fig. 7(f), cable stays 614 are installed for stabilising the outer shell 610 while the jacking frame is detached and re- attached to the next reinforcement ring. Jacking continues until the outer shell 610 has reached the required height (in this instance 200 meters tall). In Fig. 6(g) the outer shell 610 is anchored to the concrete foundation 602 and the jacking columns 604 and frames 607 removed, hi Fig. 7(h), heat exchangers 618 are installed for cooling the circulating water expelled from the condenser, hi accordance with this embodiment, the natural- draft cooling tower can be entirely constructed within 12 meters of the ground due to the jacking process. Further, the cost of constructing the cooling tower may be significantly less than conventional towers made of concrete.

It should be appreciated that the specific structure of the water conservation arrangement is not limited to that which is discussed in the preferred embodiment. For example, the water conservation arrangement may be implemented as a mechanical- draft cooling tower or Heller Cooling system for cooling the circulating before it reaches the evaporative system, hi one embodiment, a number of dry cooling towers may be implemented up-stream of an existing evaporative cooling system, for reducing the amount of evaporative loss.

It is also envisaged that the water conservation arrangement may be suitable for industrial facilities other those which are disclosed in the preferred embodiment. For example, the water conservation arrangement may be implemented for chemical plants, nuclear reactors and the like. It is also envisaged that the water conservation arrangements may be implemented on a smaller scale for commercial cooling applications.

CONSTRUCTION OF COOLING TOWERS

In the following description embodiments of the present invention are described in the context of a cooling arrangement for a thermal power generation plant, for the purposes of illustration. It will be appreciated, however, that the cooling arrangement of present invention may be implemented for any industrial facility which requires cooling, and is not limited to those embodiments discussed herein.

With reference to Fig. 8, a power plant (not shown) includes a condenser 704 for condensing steam exhausting from a turbine 705, into a liquid state. To achieve this, the exhausting steam is passed over a series of circulating water tubes 706 through which water circulates, which run through a shell 708 of the condenser 704. The resulting condensate is collected in a sump 710 which is located at the bottom of the condenser 704. The condensate may be pumped back to the power plant using a pump 709, for converting back to steam. For condensation to continue, the latent heat which is passed from the exhausting steam to the circulating water must be removed through some form of cooling. For cooling the circulating water there is provided a natural-draft dry cooling tower 714 ("dry tower 714") implemented "up-stream" of a pre-existing evaporative cooling tower 716 ("evaporative tower 716"). The basic premise of implementing a dry cooling tower to a pre-existing evaporative tower for the purpose of conserving water has been proposed in a patent application entitled "Systems and

Methods for Conserving Water" by Richard Hunwick, filed on 16 June 2006, which is herein incorporated by reference.

In accordance with an embodiment of the present invention, the cooling arrangement 712 is in the form of a dry tower 714 which is retro-fitted to surround the existing evaporative cooling tower 716, as illustrated in Figs. 8 to 10.

To allow air to pass through to the evaporative tower 716, a vent 720 is provided which substantially extends around a base 722 of the dry tower 714. In accordance with this embodiment, the vent 720 includes adjustable fins (not shown) which can be adjustably opened or closed to control a flow of air which is allowed to pass through to the evaporative tower 716. Also in accordance with this embodiment, the dry tower 714 is arranged to concentrically surround the evaporative tower 716 (see Fig. 10), to facilitate a uniform flow of air to pass between the two.

To separate air inflowing to the evaporative tower 716, from air inflowing through the cooling radiator panels 718 (which are located directly above the vent 720 for effecting cooling in the dry tower 714), the cooling arrangement 712 further includes a divider 723 (see particularly Fig. 9). The divider 723 ensures that only true ambient air is allowed to pass through to the evaporative tower 716 for efficiency.

The particular structure and configuration of the dry tower 714 will now be described. It will be appreciated that the dry tower 714 may be implemented in a standalone configuration and not only to surround a pre-existing tower as illustrated in the Figures. In an embodiment, the outer shell 724 is formed from a lightweight steel or aluminium which is coated with a corrosion-resistant paint. The outer shell 724 serves to separate the warmer buoyant air captured within the dry tower 714, from ambient air. The outer shell 724 is supported by a space frame lattice in the form of a lattice support structure 726 which, in Fig. 9, is shown as the cross-hatched section which runs adjacent to the outer shell 724 of the dry tower 714.

In a stand-alone configuration, the lattice support structure 726 is arranged to brace the outer shell 724 of the dry tower 714 to a structural steel frame 728 which is located inside the dry tower's outer shell 724. When retro-fitted to an existing tower, as illustrated in the Figures, the structural steel frame 728 may also brace to an outer shell 730 of the inner tower, i.e. evaporative tower 716.

The lattice support structure 726 is made up of a plurality of support rod members 732 in the form of high strength hollow steel tubes 732 (cold formed) which are coupled together in tetrahedral configuration by a plurality of coupling arrangements 736. One such coupling arrangement 736 is shown in Fig. 10. It can be seen that the coupling arrangement 736 is made up of a plurality of coupling elements 738, 740, 742, 734 joined together in a tetrahedral fashion for receiving the support rod members 732. According to this embodiment, four coupling elements 738, 740, 742, 734 are welded together in a tetrahedral configuration to make up the coupling arrangement 736. In this embodiment, the support rod members 732 are two metres long. The manufacture of each of the individual coupling elements which make up the coupling arrangement will now be described with particular reference to Figures 12 & 13, in accordance with an embodiment of the present invention. The coupling elements 738, 740, 742, 734 are stamped out of a continuous length of steel coil sheet 744. As shown in Fig. 12, due to the particular shape of the coupling elements 738, 740, 742, 734 there is essentially no material wastage in such a process, apart from at the edges of the sheet 744. In Fig. 13, the coupling elements 738, 740, 742, 734 are separated from the sheet 744 and bolt holes 746 are punched to accommodate bolts which will be used for securing the support rod members 732. The coupling elements 738, 740, 742, 734 each comprise a base 748 which, according to this embodiment, is shaped in the form of an equilateral triangle, and a receiving arrangement in the form of rectangular side tabs 750, 752, 754 extending outwardly and in a plane orthogonal to the equilateral base 748. Triangular end pieces 758, 760, 762 extend from the outermost end of the rectangular side tabs 750, 752, 754. Either during or after separation from the sheet 744, the rectangular side tabs 750, 752, 754 of each coupling element 738, 740, 742, 734 are bent along the dotted lines, such that their side edges 756 are in contact with those of the adjacent rectangular side tab.

Again, either before or after separation, nuts (not shown) of a suitable size are tack welded behind each bolt hole 746; these nuts are located inside the coupling element once assembled. As mentioned previously, in accordance with this embodiment the coupling arrangement 736 comprises four coupling elements 738, 740, 742, 734 which are welded together along the side edges of the triangular base 748 such that when coupled together, the triangular bases 748 define a generally tetrahedral cavity which is enclosed by the four coupling elements 738, 740, 742, 734.

Where it is determined that a coupling element would define an inner or outer surface of the lattice support structure 726, the coupling element may be closed off by bending the triangular end pieces 758, 760, 762 inwards by 90 degrees. Closing off the coupling elements and welding along the meeting side edges further strengthens the coupling elements and prevents birds and other animals from nesting inside them. The coupling arrangements 736 may be pickled and hot dipped galvanized for corrosion protection.

Prior to assembly, the ends of the support rod members 732 are crimped or otherwise formed into a triangular cross section in end view. From the perspective of either end, the triangle formed at the far end of the support member would be rotated 60 degrees relative to the triangle formed at the near end. Two or more holes are punched or drilled in each of the three triangular faces, close to the end of the support rod member, for registration with the holes 746 punched in the coupling elements 738, 740, 742, 734, once assembled. With some measure of slack, the support rod members 732 are linked into the overall tetrahedral structure of the lattice support structure 726 by means of the coupling arrangements 736.

A method of assembling the dry tower's outer shell 724 and installing the lattice support structure 726 will now be described in accordance with an embodiment of the present invention. At ground level, support rod members 732 are set upright into a concrete foundation. The length of the support rod member 732 and their spacing and layout is chosen based on the dimensions of the tower's outer shell 724. According to this embodiment the height of the outer shell 724 is 175 meters (which is sufficient to generate a suitable air flow for cooling the circulating water) and the support rod members are two meters long. Coupling arrangements 736 are inserted into the triangular ends of the vertical support rod members 732. Support rod members 732 which are intended to become diagonal struts are fitted onto the coupling arrangements 736 and loosely bolted into position using the nuts which are tacked onto the coupling elements 738, 740, 742, 734. Another layer of coupling arrangements 736 is then placed over the support rod members 732 and bolts fitted and tightened to form a tight, built-in structure. Once secured in place, construction of the dry tower's outer shell 724 begins. At an inner wall 725 of the outer shell 724, instead of fitting support rod members 732 onto the nearest coupling element 736, horizontal girts are attached by bolting. These girts have snap on fittings which snap onto clips which are provided on an inner wall 725 of the outer shell 724. Erection of the outer shell 724 and lattice support structure 726 continues and the next layer of vertical support rod members 732 is inserted into the upward facing coupling elements of the coupling arrangements 736. The process is repeated, including adding girts and erecting the outer shell 724 until it is reaches the desired height (i.e. 175 meters). In accordance with this method, the dry tower's outer shell 724 can be built both bottom up and top down, as well as where substantial partitions or blocks of the outer shell 724 are assembled away from the dry tower 714 and positioned in place by cranes or the like.

With reference to Fig. 14, there is shown an embodiment of a cooling arrangement which incorporates a circulating water distribution arrangement in the form of a collection of valves Vl, V2, V3 & V4, for controlling the distribution of circulating water to the towers 714, 716. hi general operation, valves Vl & V2 would be open, and valves V3 & V4 would be closed, forcing all of the circulating water to pass through the dry tower 714 before entering the evaporative tower 716. In the described embodiment, valves Vl & V2 may each represent many valves installed in parallel. By closing individual valves in Vl and V2 while leaving the remainder of the valves open, partial bypassing of sections of the dry cooling tower 714 (e.g. for maintenance) maybe achieved. By opening valve V3 and closing valves Vl and V2 entirely, the dry tower 714 may be bypassed altogether.

Conditions may arise, for example in cold weather, when the dry cooling capacity of the dry tower 714 is capable of meeting most, if not all, of the total cooling load. As the arrangement 712 is ordinarily designed to account for a 12 to 15 metres water gauge drop across the evaporative tower 716 (ie as a result of the circulating water passing through the distribution headers and sprays, through the packing and into the cooled water sump), a harvesting arrangement in the form of a head-recovery turbine 717 and generator 719 is provided to recover some of the potential energy represented by this fall. When it is desired to bypass the evaporative cooling tower, Valves Vl, V2 and V4 are opened, allowing water to pass through the dry tower 714 and into the head-recovery hydraulic turbine 717 and generator 719, to generate electricity.

In an alternate embodiment (not shown), the cooling arrangement 712 may comprise two circulating water pumps 721 installed in parallel, each arranged to take a predetermined percentage of the total capacity, thus allowing for partial operation of the evaporative cooling tower 716. In this configuration, the arrangement 712 may additionally comprise two head-recovery turbines and two valves V4 (e.g. one per turbine).

Other operational alternatives may be possible with this arrangement of pumps, valves and harvesting arrangements. For example, to achieve parallel operation of the towers 714, 716, some of the valves Vl and V2 would be closed, and some of the valves V3 & V4 would be open. For example, were there to be two valves each at Vl, V2 and V3, it is possible to have one of each of the two valves at each of Vl, V2 and V3 open, the other closed. The arrangement 712 may also include two booster pumps (not shown) installed directly after valve Vl for increasing the head-end pressure of the dry tower 714. In one configuration, one of these booster pumps would be on (the pumps associated with the valves open at Vl) and the other switched off (the pump associated with the valves closed at Vl) to allow some of the total circulating water flow to pass through the dry cooling tower 714. In general, with the arrangement of pumps, valves and head-recovery hydraulic turbines shown, it becomes possible to have 0 to 100% of the circulating water passing through either of the evaporative tower 716 and dry tower 714.

In the embodiment described above, the receiving arrangement of the coupling element comprised rectangular side tabs extending outwardly and in a plane orthogonal to the equilateral base and which generally defined a rectangular cross-section once assembled. It is envisaged, however, that the receiving arrangement may also be shaped/cut so as to form generally circular cross-sections (for example, similar to "Downee fittings") thereby avoiding the need for crimping ends of the support rod members.

CONSTRUCTION OF HEAT EXCHANGER

In the following description, the present invention has been described in the context of a heat exchanger panel for a natural-draft or mechanical-draft cooling tower, for the purposes of illustration. It will be appreciated, however, that the heat exchanger panels of the present invention may be implemented for any application which requires cooling or transfer of heat energy to or from the ambient air, and is not limited to those embodiments discussed herein. It should also be appreciated that the specified dimensions have been chosen to suit an embodiment of a particular application and again should in no way be seen as limiting the present invention.

A method of forming a heat exchanger panel in accordance with an embodiment of the present invention will now be described with reference to the flow diagram of Fig. 15 and various elevational views and sectional views shown in Figs. 16 to 19. It is noted that Figs. 16 to 19 are not to scale, and only serve to conceptually illustrate the method of forming a heat exchanger panel in accordance with an embodiment of the present invention. According to the described embodiment, the raw sheet material which is used to form the heat exchanger panel is Aluminium sheet or coil having a width of 1.2 metres and thickness of approximately 2mm. The alloy is chosen for its formability and resistance to creep below a particular threshold, depending on the dimensions of the heat exchanger panel. With reference to Fig. 15, the method begins at step 802, where a coil of Aluminium sheet material is unwound and slotted. A plan view of a 150mm wide section of the unwound sheet 814 is shown in Fig. 16. According to this embodiment a slitting device (not shown) is positioned above the unwound sheet 814 and operates to make a series of longer horizontal slits 816 and shorter horizontal slits 818 which run the length of the sheet 814. According to this embodiment, the longer horizontal slits are 60mm wide, while the shorter horizontal slits 818 are 50mm wide. Although not visible in Fig. 16, the illustrated slit pattern is repeated across the full width of the unwound sheet 814.

At step 804, the unwound sheet 814 is stretched in a longitudinal direction (i.e. in line with the motion of the sheet) using a suitable stretching device, to yield the profile which is shown in Fig. 17. As a result of the stretching process, the longer horizontal slits 816 stretch open to form elongate hexagonal holes 822 which will eventually form a passage through which circulating water will flow. Located between the elongate hexagonal holes 822 are a series of secondary holes in the form of generally regular hexagonal holes 824 which are formed from the shorter horizontal slits 818, as a result of stretching the unwound sheet 814.

The next step in the process (step 806), is to form the fins for the air-side heat transfer surface. This step involves drawing the partitions 826 which are located between each adjacent elongate hexagonal hole 822, using a press or other suitable drawing apparatus. In accordance with this embodiment, the partitions 826 between the adjacent elongate hexagonal holes 822 are deep-drawn vertically in a downwards direction (i.e. "into the paper"). The unwound sheet 814 is then further stretched to form thinned tapered fins 828 which extend between each adjacent elongate hexagonal hole 822, as shown in plan view in Fig. 18. As a result of the further stretching, the generally regular hexagonal holes 824 also stretch in a longitudinal direction to form elongate octagonal holes 830.

In step 808, the unwound sheet 814 is cut, using a suitable cutting tool or machine, into individual sheet elements of a desired length and width. In accordance with this embodiment, the selected width is 150mm so as to include two horizontally opposing elongate hexagonal holes 822. The left-most elongate hexagonal holes 822 shown in Fig. 18 will eventually form an "up pass" for circulating water which will pass through the heat exchanger, while the right-most elongate hexagonal holes 822 will form the "down pass". The length of each sheet element is 2.5 meters and includes a plurality of both "up pass" and "down pass" elongate hexagonal holes 822 running the length thereof. It should readily be appreciated, however, that the selected length and width of the individual sheet elements may be chosen to incorporate as many or as little elongate hexagonal holes 822 as is required for the particular application.

Once the individual sheet elements have been cut out of the unwound sheet 814, they are stacked on top of each other such that each of the "up pass" and "down pass" elongate hexagonal holes 822 are in registration with the corresponding "up pass" and "down pass" elongate hexagonal holes 822 of the adjacent sheet elements (step 810). In step 812, a securing device is coupled through the elongate octagonal holes 830 to compress and secure the individual sheet elements together, thereby forming a heat exchanger panel. According to this embodiment, the securing device is in the form of tie rods which pass through the elongate octagonal holes 830 (which are also in registration) and act to tightly compress the individual sheet elements together.

Fig. 19 is a part sectional view along the axis E-E of Fig. 18, showing a plurality of stacked and compressed sheet elements. As shown, the plurality of "up pass" and "down pass" elongate hexagonal holes 822, when stacked, form a plurality of passages or bores 830 which may carry a flow of circulating water through the heat exchanger panel for cooling. Heat is transferred from the circulating water to an airflow which passes through the thinned tapered fins 828 which extend outwardly from each of the elongate hexagonal holes 226. When used in a cooling tower configuration, operating water pressures within the heat exchanger panel would typically not exceed more than two to four Bar gauge.

The heat exchanger panels may be coupled to other heat exchanger panels by piping, where a greater level of cooling is required. For example, an average size cooling tower may employ 300 heat exchanger panels which are coupled together to suitably cool the circulating water outputted from a condenser which is coupled to a power plant. For such applications, each heat exchanger panel may be roughly 20 meters long and comprise 10,000 stacked sheet elements, for achieving a desired level of cooling.

hi an embodiment, the inside surface (water side surface) of the passages 830 is coated with a suitable sealant for preventing leakage of circulating from between the compressed individual sheet elements. For cooling tower applications, the sealant may also be resilient to the brackish (dissolved salts up to 3000 ppm mostly Na, Ca and Mg bicarbonates, chlorides and sulphates) circulating cooling water which will pass through the bores. In the embodiment described above the individual sheet elements were made from aluminium sheet, however it is envisaged that the heat exchanger could equally be formed of other convenient material which is not subject to breaking during a forming process including, for example, deformable steel, copper or titanium. In another embodiment it is envisaged that the sheet may be made of a thermally conductive plastics material.

A reference herein to a prior art document is not an admission that the document forms part of the common general knowledge in the art in Australia.

hi the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method of conserving water including the steps of implementing a water conservation arrangement to reduce the amount of water consumed by an industrial facility for the purpose of cooling.

2. A method as claimed in claim 1, wherein the industrial facility is an electrical power generation plant employing an evaporative cooling system and wherein the step of implementing a water conservation arrangement includes additionally installing a dry cooling system.

3. A method as claimed in claim 2, comprising the further step of installing the dry cooling system upstream of the evaporative cooling system.

4. A method as claimed in claim 3, comprising the further step of providing a distribution arrangement for controlling a flow of fluid to and/or between the evaporative cooling system and dry cooling system, for cooling.

5. A method as claimed in claim 4, comprising the further step of providing a harvesting arrangement for harvesting potential energy from the fluid when one of the dry cooling system and evaporative cooling system is partially or entirely bypassed using the distribution arrangement.

6. A method as claimed in claim 5, wherein the harvesting arrangement comprises a turbine coupled to a generator.

7. A method as claimed in any one of claims 4 to 6, wherein the distribution arrangement comprises at least one adjustable valve.

8. A method as claimed in any one of claims 4 to 7, wherein the fluid is circulating water outputted from a condenser which cools the power generation plant.

9. A method as claimed in any one of claims 2 to 8, wherein the dry cooling system has a cooling capacity based on a desired evaporative loss in the evaporative cooling system.

10. A method as claimed in claim 9, wherein the dry cooling system has a cooling capacity which is equal to a desired reduction in evaporative loss in the evaporative cooling system, the reduction in evaporative loss being calculated by predicting an amount of heat which would be rejected by the dry cooling system and also by the evaporative cooling system using key climate data

11. A method as claimed in any one of claims 4 to 10, wherein only the dry cooling system is operational for cooling below a predefined ambient temperature.

12. A method as claimed in claim 11, wherein the predefined ambient temperature is dependent on at least one of a cooling capacity of the dry cooling system and cooling capacity of the evaporative cooling system.

13. A method as claimed in any one of the preceding claims, comprising the further the step of determining an amount of water conserved by implementing the water conservation arrangement and selling the amount of conserved water.

14. A method as claimed in claim 13, wherein the amount of conserved water is sold to other consumers.

15. A method as claimed in claim 13, wherein the amount of conserved water is sold to a water controlling authority.

16. A method as claimed in claims 14 or 15, wherein the amount of conserved water is sold to one of the other consumers or water controlling authority at an economic price.

17. A method as claimed in any one of claims 13 to 16, wherein for a power generation plant not already employing an evaporative cooling system, the step of determining the amount of conserved water includes predicting the amount of water which would be consumed if the power generation plant had employed an evaporative cooling system.

18. A system for conserving water including a water conservation arrangement implemented in an industrial facility, the water conservation arrangement being in the form of a dry cooling system implemented in addition to an existing evaporative cooling system.

19. A system as claimed in claim 18, further comprising a distribution arrangement for controlling a flow of fluid to and/or between the dry cooling system and existing evaporative cooling system.

20. A system as claimed in claim 19, further comprising a harvesting arrangement for harvesting potential energy from the fluid when one of the dry cooling system and existing evaporative cooling system is partially or entirely bypassed using the distribution arrangement.

21. A system as claimed in claim 20, wherein the harvesting arrangement comprises a turbine coupled to a generator.

22. A system as claimed in any one of claims 18 to 21, wherein the distribution arrangement comprises at least one adjustable valve.

23. A system as claimed in any one of claims 18 to 22, wherein the dry cooling system is a dry cooling tower.

24. A system as claimed in claim 23, wherein the dry cooling tower is one of a mechanical-draft dry cooling tower and natural-draft dry cooling tower.

25. A system as claimed in any one of claims 18 to 24, wherein the existing evaporative cooling system is at least one of an evaporative cooling tower and a body of water.

26. A system as claimed in any one of claims 18 to 25, wherein the industrial facility is an electrical power generation plant including a condenser and wherein the dry cooling tower, when in use, is arranged to cool water outputted from the condenser before it is cooled by the existing evaporative cooling system.

27. A system as claimed in any one of claims 18 to 26, wherein the dry cooling system has a dry cooling capacity based on a desired evaporative loss.

28. A system as claimed in claim 27, wherein the evaporative loss is determined in accordance with the method steps of determining key climate data applying to a location of the industrial facility, selecting a desired cooling capacity of the dry cooling system, predicting an amount of heat which would be rejected by the dry cooling system and evaporative cooling system based on the key climate data and cooling capacity of the dry cooling system, and based on the amount of heat which is rejected by the evaporative cooling system determining the evaporative loss.

29. A method of constructing a cooling tower comprising the steps of fabricating an outer shell of the cooling tower out of a plurality of partitions.

30. A method of constructing a cooling tower as claimed in claim 29, wherein the plurality of partitions are formed of light-weight material.

31. A method as claimed in claim 30, wherein the light-weight material is steel or aluminium.

32. A method of constructing a cooling tower as claimed in any one of claims 29 to 31, comprising the further step of fabricating the outer shell through a jacking process.

33. A method of constructing a cooling tower as claimed in claim 32, wherein the outer shell is fabricated top down.

34. A method as claimed in any one of claims 29 to 33, wherein the cooling tower is a natural-draft cooling tower.

35. A method as claimed in claim 34, comprising the further step of installing heat exchangers around a base of the natural-draft cooling tower's outer shell.

36. A cooling tower comprising an outer shell which is constructed of a light- weight material.

37. A cooling tower as claimed in claim 36, wherein the light-weight material is aluminium or steel.

38. A method of selling water which is conserved by a water conservation arrangement implemented in an industrial facility to reduce the amount of water consumed for the purpose of cooling, comprising the steps of determining an amount of water conserved by implementing the water conservation arrangement and selling the amount of conserved water.

39. A computer program including instructions for controlling a computing apparatus to implement a method in accordance with claim 10.

40. A computer program including instructions for controlling a computing apparatus to implement a method in accordance with claim 39.

41. A computer readable medium providing a computer program in accordance with claim 39.

42. A computer readable medium providing a computer program in accordance with claim 40.

43. A cooling tower comprising an outer shell supported by a space frame lattice.

44. A cooling tower as claimed in claim 43, wherein the outer shell is formed from a plurality of partitions.

45. A cooling tower in accordance with either of claims 43 or 44, wherein the outer shell is formed from metal.

46. A cooling tower in accordance with claim 45, wherein the metal is aluminium.

47. A cooling tower in accordance with any of the preceding claims 43 to 46, wherein the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement.

48. A cooling tower in accordance with claim 47, wherein the support rod members are coupled together by a coupling arrangement.

49. A cooling tower in accordance with claim 48, wherein the coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members.

50. A cooling tower in accordance with claim 49, wherein the coupling elements are formed from sheet metal.

51. A cooling tower in accordance with claim 50, wherein the sheet metal is steel.

52. A cooling tower in accordance with any one of the preceding claims 43 to 51, wherein the cooling tower is formed about an existing cooling tower.

53. A cooling tower in accordance with claim 52, wherein the cooling tower concentrically surrounds the existing cooling tower.

54. A cooling tower in accordance with claims 52 or 53, wherein the cooling tower is a dry cooling tower and the existing cooling tower is an evaporative cooling tower.

55. A cooling tower in accordance with claims 52 or 53, wherein the space frame lattice is braced to the existing cooling tower.

56. A cooling tower in accordance with any one of claims 52 to 55, wherein the cooling tower is arranged to cool a flow of water before it is passed to the existing cooling tower for cooling.

57. A cooling tower in accordance with any one of claims 52 to 56, wherein a void is located in the cooling tower for allowing air flow to the existing cooling tower.

58. A cooling tower in accordance with claim 57, wherein the void extends along a base of the cooling tower.

59. A cooling arrangement for an industrial facility comprising a cooling tower which is formed about an existing cooling tower.

60. A cooling arrangement as claimed in claim 59, wherein an outer shell of the cooling tower is formed from metal.

61. A cooling arrangement as claimed in claim 60, wherein the metal is aluminium.

62. A cooling arrangement in accordance with any one of claims 59 to 61, wherein the cooling tower concentrically surrounds the existing cooling tower.

63. A cooling arrangement as claimed in claim 62, wherein the cooling tower co- axially surrounds the existing cooling tower.

64. A cooling arrangement in accordance with any one of claims 59 or 63, wherein the cooling tower is a dry cooling tower and the existing cooling tower is an evaporative cooling tower.

65. A cooling arrangement in accordance with any one of claims 59 to 64, wherein the cooling tower is supported by a space frame lattice.

66. A cooling arrangement in accordance with claim 65, wherein the space frame lattice is braced to the existing cooling tower.

67. A cooling arrangement in accordance with any one of claims 65 or 66, wherein the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement.

68. A cooling arrangement in accordance with claim 67, wherein the support rod members are coupled together by coupling arrangements.

69. A cooling arrangement in accordance with claim 68, wherein each coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members.

70. A cooling arrangement in accordance with any one of claims 59 to 69, further comprising a circulating water distribution arrangement for controlling a flow of circulating water to and/or between the towers.

71. A cooling arrangement in accordance with claim 70, further comprising a harvesting arrangement for harvesting potential energy from the circulating water when one of the towers is partially or entirely bypassed using the circulating water distribution arrangement.

72. A cooling arrangement in accordance with claim 71, wherein the harvesting arrangement comprises a turbine coupled to a generator.

73. A cooling arrangement in accordance with any one of claims 70 to 72, wherein the circulating water distribution arrangement comprises at least one adjustable valve.

74. A cooling arrangement in accordance with any one of claims 59 to 73, wherein a void is located in the cooling tower for allowing air flow to the existing cooling tower.

75. A cooling arrangement in accordance with claim 71, wherein the void extends along a base of the cooling tower.

76. An industrial facility incorporating a water conservation arrangement to reduce the amount of water consumed by an industrial facility for the purpose of cooling, the water conservation arrangement comprising a dry cooling tower which is formed about, and upstream, of an existing cooling tower.

77. An industrial facility in accordance with claim 76, wherein the dry cooling tower concentrically surrounds the existing cooling tower.

78. An industrial facility in accordance with claim 77, wherein the dry cooling tower co-axially surrounds the existing cooling tower.

79. An industrial facility in accordance with any one of claims 76 to 78, wherein an outer shell of the dry cooling tower is formed from metal.

80. An industrial facility in accordance with claim 79, wherein the metal is aluminium.

81. An industrial facility in accordance with any one of claims 76 to 80, wherein the dry cooling tower is supported by a space frame lattice.

82. An industrial facility in accordance with claim 81, wherein the space frame lattice is braced to the existing cooling tower.

83. An industrial facility in accordance with any one of claims 81 or 82, wherein the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement.

84. An industrial facility in accordance with claim 83, wherein the support rod members are coupled together by coupling arrangements.

85. An industrial facility in accordance with claim 84, wherein each coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members.

86. A cooling arrangement in accordance with any one of claims 76 to 85, further comprising a circulating water distribution arrangement for controlling a flow of circulating water to and/or between the towers.

87. A cooling arrangement in accordance with claim 86, further comprising a harvesting arrangement for harvesting potential energy from the circulating water when one of the towers is partially or entirely bypassed using the circulating water distribution arrangement.

88. A cooling arrangement in accordance with claim 87, wherein the harvesting arrangement comprises a turbine coupled to a generator.

89. A cooling arrangement in accordance with any one of claims 86 to 88, wherein the circulating water distribution arrangement comprises at least one adjustable valve.

90. An industrial facility in accordance with any one of claims 76 to 89, wherein a void is located in the cooling tower for allowing air flow to the existing cooling tower.

91. An industrial facility in accordance with claim 90, wherein the void extends along a base of the cooling tower.

92. A space frame lattice, when in use, arranged to secure a cooling tower to an existing cooling tower.

93. A space frame lattice in accordance with claim 92, the space frame lattice comprising a plurality of support rod members coupled together in a tetrahedral arrangement.

94. An industrial facility in accordance with claim 93, wherein the support rod members are coupled together by coupling arrangements.

95. An industrial facility as claimed in claim 94, wherein each coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members.

96. A coupling element arranged to couple a support rod member to a coupling arrangement within a space frame lattice, the coupling element comprising a base which is arranged to be coupled to other coupling elements within the coupling arrangement and further comprising a receiving arrangement which, when in use, extends outwardly from the base to receive the support member.

97. A coupling element in accordance with claim 96, wherein the base and receiving member are of one-piece construction formed from a piece of sheet metal.

98. A coupling element in accordance with either one of claims 96 or 97, wherein the base defines a generally planar triangular shape.

99. A coupling element in accordance with claim 98, wherein the side walls of the base are of equal length.

100. A coupling element in accordance with claim 99, wherein the receiving arrangement comprises three generally rectangular elements, each rectangular element extending from a separate side wall of the base.

101. A coupling element in accordance with claim 100, wherein the rectangular elements extend outwardly from each side wall in a plane orthogonal to the base.

102. A coupling element in accordance with claim 101, wherein each rectangular element further comprises a triangular tab extending from a distal end thereof, the triangular tabs arranged to bend inwardly to enclose a cavity which is formed as the rectangular elements extend from the base.

103. A coupling element in accordance with any one of claims 96 to 102, wherein the support member comprises a hollow tube having triangular ends which are arranged to either fit over the rectangular elements or within the cavity defined thereby.

104. A coupling element in accordance with any one of claims 96 to 103, wherein a securing arrangement is provided on the receiving arrangement for securing the support member to the coupling element.

105. A coupling arrangement for coupling a plurality of support members together within a space frame lattice, the coupling arrangement comprising a plurality of coupling elements, each coupling element comprising a base which is arranged to be coupled to other coupling elements within the coupling arrangement and further comprising a receiving arrangement which, when in use, extends outwardly from the base to receive one of the support rod members, the coupling elements fixedly coupled together in a predetermined configuration.

106. A coupling arrangement for coupling a plurality of support members together within a space frame lattice, the coupling arrangement comprising four coupling elements, each coupling element comprising a triangular base and a receiving arrangement which, when in use, extends outwardly from the triangular base to receive one of the support rod members, the coupling elements being fixedly coupled together such that an enclosed generally tetrahedral cavity is formed by their bases.

107. A coupling arrangement in accordance with either of claims 106 or 107, wherein the coupling elements are welded together.

108. A method of constructing a cooling tower, the method including the steps of fabricating an outer shell of the cooling tower and supporting the outer shell with a space frame lattice.

109. A method of constructing a cooling tower in accordance with claim 108, comprising the further step of forming the outer shell from a plurality of partitions.

110. A method of constructing a cooling tower in accordance with either of claims 108 or 109, wherein the outer shell is formed from metal.

111. A method of constructing a cooling tower in accordance with claim 110, wherein the metal is aluminium.

112. A method of constructing a cooling tower in accordance with any one of claims 108 to 111, wherein the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement.

113. A method of constructing a cooling tower in accordance with claim 112, comprising the further step of coupling the support rod members together using a coupling arrangement.

114. A method of constructing a cooling tower in accordance with claim 113, wherein the coupling arrangement comprises a plurality of coupling elements which are arranged to receive the support rod members.

115. A method of constructing a cooling tower in accordance with claim 114, wherein the coupling elements are formed from sheet metal.

116. A method of constructing a cooling tower in accordance with claim 115, wherein the sheet metal is aluminium.

117. A method of constructing a cooling tower in accordance with any one of claims 108 to 116, comprising the further step of forming the cooling about an existing cooling tower.

118. A method of constructing a cooling tower in accordance with claim 117, comprising the further step of forming the cooling tower to concentrically surround the existing cooling tower.

119. A method of constructing a cooling tower in accordance with claim 118, comprising the further step of forming the cooling tower to co-axially surround the existing cooling tower.

120. A method of constructing a cooling tower in accordance with any one of claims 117 to 119, wherein the cooling tower is a dry cooling tower and the existing cooling tower is an evaporative cooling tower.

121. A method of constructing a cooling tower in accordance with any one of claims 117 to 120, comprising the further step of bracing the existing cooling tower to a space frame lattice.

122. A method of constructing a cooling tower in accordance with any one of claims 117 to 121, comprising the further step of providing a circulating water distribution arrangement for controlling a flow of circulating water to and/or between the towers.

123. A method of constructing a cooling tower in accordance with claim 122, comprising the further step of providing a harvesting arrangement for harvesting potential energy from the circulating water when one of the towers is partially or entirely bypassed using the circulating water distribution arrangement.

124. A method of constructing a cooling tower in accordance with claim 123, wherein the harvesting arrangement comprises a turbine coupled to a generator.

125. A method of constructing a cooling tower in accordance with any one of claims 122 to 124, wherein the circulating water distribution arrangement comprises at least one adjustable valve.

126. A method of constructing a cooling tower in accordance with any one of claims 117 to 125, comprising the further step of providing a void in the cooling tower for allowing air flow to the existing cooling tower.

127. A method of constructing a cooling tower in accordance with claim 126, wherein the void extends along a base of the cooling tower.

128. A method of constructing a cooling arrangement for an industrial facility, the method comprising the steps of forming a cooling tower about an existing cooling tower.

129. A method of constructing a cooling arrangement as claimed in claim 128, comprising the further step of forming an outer shell of the cooling tower from metal.

130. A method of constructing a cooling arrangement as claimed in claim 129, wherein the metal is aluminium.

131. A method of constructing a cooling arrangement in accordance with any one of claims 128 to 130, comprising the further step of forming the cooling to concentrically surround the existing cooling tower.

132. A method of constructing a cooling arrangement in accordance with any one of claims 128 to 131, wherein the cooling tower is a dry cooling tower and the existing cooling tower is an evaporative cooling tower.

133. A method of constructing a cooling arrangement in accordance with any one of claims 128 to 132, comprising the further step of supporting the cooling tower using a space frame lattice.

134. A cooling arrangement in accordance with claim 133, comprising the further step of bracing the cooling tower to the existing cooling tower using the space frame lattice.

135. A cooling arrangement in accordance with any one of claims 133 or 134, wherein the space frame lattice comprises a plurality of support rod members coupled together in a tetrahedral arrangement.

136. A method of manufacturing a coupling element in accordance with any one of claims 96 to 103, the method comprising the steps of cutting out a former from a piece of sheet metal and bending the former to produce the base and receiving means.

137. A method of manufacturing a coupling arrangement for coupling a plurality of support members together within a space frame lattice, the method comprising the steps of joining a plurality of coupling elements as claimed in any one of claims 96 to 104, the coupling elements being been cut from a piece of sheet material.

138. A method of manufacturing a heat exchanger from a plurality of sheets, the method comprising the steps of forming holes in the sheets and stacking the sheets together such that the holes are in registration to provide passages for the flow of fluid for heat exchange.

139. A method as claimed in claim 138, wherein the step of forming holes comprises making slits in the sheets and stretching the sheets to form the holes.

140. A method as claimed in claim 139, further comprising the step of drawing at least one partition which separates adjacently located holes on the sheets and further stretching the sheets to form inwardly tapered fins which extend between the adjacently located holes for heat transfer.

141. A method as claimed in claim 140, wherein the step of drawing comprises deep-drawing the partition.

142. A method as claimed in any one of the preceding claims 138 to 141, wherein the method comprises the further step of forming secondary holes in the sheets, such that when the sheets are stacked together the secondary holes are in registration to provide at least one secondary passage for receiving a securing device for fixedly securing the sheets together.

143. A method as claimed in claim 142, wherein the step of forming secondary holes comprises making secondary slits in the sheets and stretching the sheets to form the secondary holes.

144. A method as claimed in claim 143, wherein the securing device is further arranged to compress the sheets.

145. A method as claimed in claim 144, wherein the securing device comprises one or more tie rod(s).

146. A method as claimed in any one of the preceding claims 138 to 145, wherein an inside face of the passages is coated with a sealant to prevent leakage of fluid from between the stacked sheets.

147. A method as claimed in any one of the preceding claims 138 to 146, wherein the sheets are metal sheets.

148. A method as claimed in claim 147, wherein the sheets are made from deformable aluminium or copper.

149. A method as claimed in claim 147, wherein the sheets are made from thermally conductive plastics.

150. A heat exchanger which is formed from a plurality of sheets which are stacked together, the sheets comprising holes such that when the sheets are stacked together the holes are in registration to form passages for the flow of fluid for heat exchange.

151. A heat exchanger as claimed in claim 150, wherein the holes are formed from making slits in the sheets and stretching the sheets to form the holes.

152. A heat exchanger as claimed in claim 151, further comprising inwardly tapered fins which extend between the adjacently located holes on each sheet, the fins being formed by drawing at least one partition which separates the adjacently located holes on the sheets and further stretching the sheets to form inwardly tapered fins which extend between the adjacently located holes for heat transfer.

153. A heat exchanger as claimed in any one of claims 150 to 152, wherein each sheet comprises secondary holes, such that when the sheets are stacked together the secondary holes are in registration to provide a secondary passage for receiving a securing device which compresses the sheets.

154. A heat exchanger as claimed in claim 153, wherein the secondary holes are formed from making secondary slits in the sheets and stretching the sheets to form the secondary holes.

155. A heat exchanger as claimed in claim 154, wherein the securing device comprises one or more tie rod(s).

156. A heat exchanger as claimed in any one of the preceding claims 150 to 155, wherein an inside face of the passages is coated with a sealant to prevent leakage of fluid from between the stacked sheets.

157. A heat exchanger as claimed in any one of claims 150 to 156, wherein the sheets are metal sheets.

158. A heat exchanger as claimed in claim 157, wherein the sheets are made from deformable aluminium, copper or thermally conductive plastics.