AU2009227990A1

AU2009227990A1 - A device and method for utilising surplus cooling of water in a cooling tower

Info

Publication number: AU2009227990A1
Application number: AU2009227990A
Authority: AU
Inventors: Stephen Shelley
Original assignee: Creative Water Technology Ltd
Current assignee: Creative Water Technology Ltd
Priority date: 2008-03-28
Filing date: 2009-03-27
Publication date: 2009-10-01
Anticipated expiration: 2029-03-27
Also published as: WO2009117777A1; AU2009227990B2; CN102046254A; US20110011107A1

Description

WO 2009/117777 PCT/AU2009/000347 1 A DEVICE AND METHOD FOR UTILISING SURPLUS COOLING OF WATER IN A COOLING TOWER 5 The present invention relates to a device and method for utilizing surplus cooling of water in a cooling tower. More particularly, invention relates to a device and method for utilizing surplus cooling of water in a cooling tower to produce water and will herein be generally described in that context. However, it is to be appreciated that the invention may be readily adapted for use in 10 other applications. Cooling towers are often designed and configured to operate in adverse temperatures when the need for effective cooling performance is at its highest. Thus, when cooling towers operate in more favourable conditions, they tend to 15 cool the water passing therethrough to a temperature lower than that necessary. This results in excessive energy being used to cool water within the cooling tower and unnecessary loss of water. It would be desirable to be able to at least partially utilize the energy used to 20 excessively cool water in cooling towers and to recover the water that has been unnecessarily evaporated off. Further, given that the water recovered from the moist air stream will be somewhat cleaner than the water entering the cooling tower, it would also be 25 desirable to utilize any excessive cooling of water in cooling towers to produce clean water. The present invention aims to at least partially address these desirabilities. 30 According to a broad aspect of the present invention, there is provided a device for reclaiming water from moist air discharged from a cooling tower.

WO 2009/117777 PCT/AU2009/000347 2 The device includes a heat exchanger. The heat exchanger includes an air flow path extending between an air inlet port and an air outlet port, and a water flow path extending between a water inlet port and a water outlet port. 5 The heat exchanger is configured for, in use, mounting the air inlet port at least partially in a flow path of air discharged from the cooling tower to generate a flow of (at least initially) warm, moist air through the heat exchanger along the air flow path. The heat exchanger is also configured for fluidly connecting the water inlet port to the water cooled in the cooling tower, and fluidly connecting 10 the water outlet port to the water cooled in the cooling tower. The device includes a pump for pumping water about a water flow loop. The water flow loop extends from water cooled in the cooling tower, through the heat exchanger along the water flow path from the water inlet port to the water 15 outlet port, and from the water outlet port back to the water cooled in the cooling tower. The water reclaiming device would typically also include a control device provided for controlling the flow rate of water pumped about the water flow 20 loop by the pump. If included, the control device controls the flow rate of water pumped about the water flow loop and in a typical configuration would be at least partially dependent upon the temperature of water cooled in the cooling tower. 25 The water reclaiming device further includes a water collection device for mounting downstream of the air outlet port for collecting water condensed from moist air flowing along the air flow path. In a particularly preferred form, the control device includes a water temperature 30 sensor for mounting in the water cooled in the cooling tower. It is envisaged that the water temperature sensor would be configured for mounting in the water flow loop upstream of the water inlet port. However, it is to be appreciated that the temperature sensor may be mounted at any other location suitable for sensing the temperature of water cooled by the cooling tower.

WO 2009/117777 PCT/AU2009/000347 3 Thus, the water temperature sensor may be mounted directly within a cooled water collection basin or the like within the lower reaches of the cooling tower. In a preferred form, the water reclaiming device includes a flue. The flue 5 preferably includes an inlet for receiving warm, moist air discharged from the cooling tower and an outlet for discharging air into the air inlet port of the heat exchanger. The flue inlet may be configured for fitting to or about the cooling tower air outlet port; and the flue outlet may be configured for fitting to or about the air inlet port of the heat exchanger. 10 The water reclaiming device may further include an exhaust section for discharging or expelling air exiting the heat exchanger's air outlet port to the atmosphere. In this regard, the exhaust section may include an exhaust section inlet for fitting to or about the air outlet port of the heat exchanger, and 15 an air outlet for directing air exiting the exhaust section to the atmosphere. It is to be appreciated that the flue and exhaust section may be configured as an at least partially integrated unit, with the heat exchanger receivable in, fitted to or integrated with the at least partially integrated unit. 20 The air exiting the heat exchanger air outlet port need not be directed to or expelled to the atmosphere. Instead, this air (which has been cooled on passing through the heat exchanger) may be directed back through a cooling tower air inlet to assist in cooling the heated water entering the cooling tower. 25 In this regard, a return section for returning air exiting the air outlet port to an air inlet of the cooling tower may be provided. The flue and return section may be at least partially integrated. 30 Indeed, if desired, part of the cooled air exiting the heat exchanger may be directed to the atmosphere and part returned to the cooling tower (or directed elsewhere). An arrangement may be provided for altering the ratio of air directed to the atmosphere to air returned to the cooling tower. In this WO 2009/117777 PCT/AU2009/000347 4 arrangement, the flue, return section and exhaust section may be at least partially integrated. In a preferred form, in a configuration that includes a control device, the water 5 reclaiming device includes an interface. The interface may include a temperature selector for selecting a desired temperature of water cooled in the cooling tower. In this regard, the temperature selector may be operably connected to the pump to generate a flow rate of water about the water flow loop dependent upon, for example, any difference between the temperature of 10 water cooled in the cooling tower sensed by the temperature sensor and a desired temperature of water cooled in the cooling tower. If the temperature of water cooled in the cooling tower is lower than required (or desired) then some of the water cooled in the cooling tower may be directed through the heat exchanger to cool the warm, moist air exiting the cooling tower. This 15 condenses at least some of the moisture in the warm, moist air, thereby reclaiming water from the warm moist air. The pump may be powered by any suitable means such as, for example, an electrically powered pump. 20 The invention has, so far been generally described in terms of a water reclaiming device for use in reclaiming water from warm, moist air exiting a cooling tower. The device may be retro-fitted to existing cooling towers, or may be incorporated into new cooling towers. Thus, it is to be appreciated that the 25 invention also relates to a cooling tower including a water reclaiming device of the type broadly described above. The present invention also relates to a method of reclaiming relatively clean water from moist air discharged from a cooling tower. 30 The method includes directing air along an air flow path of a heat exchanger extending between an air inlet port and an air outlet port.

WO 2009/117777 PCT/AU2009/000347 5 The method further includes pumping water about a water flow loop extending from water cooled in the cooling tower, along a water flow path of the heat exchanger extending between a water inlet port and a water outlet port, and from the water outlet port back to the water cooled in the cooling tower. 5 The method also includes controlling the flow rate of water pumped about the water flow loop, at least partially dependent upon the temperature of water cooled in the cooling tower; and collecting water condensed from moist air flowing along the air flow path downstream of the air outlet port. 10 The method may include directing air downstream of the air outlet port to the atmosphere or back to an air inlet of the cooling tower. The air downstream of the air outlet port may also be part directed to the atmosphere and part directed to a cooling tower air inlet. 15 The method may include the step of manually inputting into a control device a desired temperature of water cooled in the cooling tower. This may be advantageous because it provides an operator with a means for manually altering the temperature of cooled water leaving the cooling tower and re 20 circulating about a building air-conditioning system. The method preferably further includes the control device controlling the flow rate of water pumped about the water flow loop. 25 It will be convenient to hereinafter describe a preferred embodiment of the invention with reference to the accompanying drawing. The particularity of the drawing is to be understood as not limiting the preceding broad description of the invention. 30 Figure 1 is a schematic side view of a device 10 for reclaiming water from warm, moist air discharged from a cooling tower in accordance with one embodiment of the present invention and illustrated in conjunction with a cooling tower.

WO 2009/117777 PCT/AU2009/000347 6 Referring to Figure 1, the device 10 includes a heat exchanger 16 configured as a condenser for condensing the warm, moist air 12 discharged from a cooling tower 14 through a cooling tower air outlet 15. The heat exchanger 16 includes an air flow path 18 extending between an air inlet port 20 and an air 5 outlet port 22, and a water flow path 24 extending between a water inlet port 26 and a water outlet port 28. The water reclaiming device 10 includes a flue 30. The flue 30 includes an inlet 32 for receiving the warm, moist air 12 discharged from the cooling tower 14 10 and an outlet 34 for discharging the warm, moist air 12 into the heat exchanger air inlet port 20. In this respect, the flue inlet 32 is fitted to or about the cooling tower air outlet 15; and the outlet 34 is fitted to or about the air inlet port 20 of the heat exchanger 16. 15 This arrangement directs warm, moist air 12 discharged from the cooling tower 14 through outlet 15 through the heat exchanger 16 along the air flow path 18, where at least some of the moisture in the warm, moist air is condensed. The water inlet port 26 of the heat exchanger 16 is fluidly connected to the 20 water 36 at the bottom of the cooling tower 14, which has been cooled in the cooling tower 14. The water outlet port 28 of the heat exchanger 16 is, likewise, fluidly connected to the water cooled at the bottom of the cooling tower 14. A water flow loop 29 (shown in dashed line format) is thus, defined extending from water 36 cooled in the cooling tower 14, to the water inlet port 25 26, through the heat exchanger 16 along the water flow path 24 from the water inlet port 26 to the water outlet port 28, and from the water outlet port 28 back to the water 36 cooled in the cooling tower 14. The cooled water passing through the heat exchanger 16 along the water flow 30 path 24 cools the warm, moist air flowing along the air flow path 18, such that at least some of the moisture in the air is condensed in the air flow path 18.

WO 2009/117777 PCT/AU2009/000347 7 The device 10 includes a pump 38 for pumping water about the water flow loop 29. The pump 10 may be powered by any suitable means and in the illustrated embodiment is an electrically powered pump. 5 An exhaust section 40 is provided for discharging or expelling air exiting the air outlet port 22 to the atmosphere. The exhaust section 40 includes an inlet 41 for fitting to (or about) the air outlet port 22 of the heat exchanger 16, and an air outlet 43 for directing air exiting the exhaust section 40 to the atmosphere. 10 A lower portion of the exhaust section 40 includes a water collection device in the form of a receptacle 42 (also mounted downstream of the air outlet port 22) for collecting clean water condensed from the warm, moist air 12 passing through the heat exchanger 16. Water collected in the receptacle 42 may be used for any desired purpose. In the illustrated embodiment, water collected in 15 the receptacle 42 is removed via a pipe 44. It is to be appreciated that the water collected in the receptacle is likely to be significantly cleaner than the water entering the cooling tower. It is to be appreciated that the flue 30 and exhaust section 40 may be an at 20 least partially integrated unit, with the heat exchanger 16 receivable in, fitted to or integrated with the at least partially integrated unit. A control device 46 is provided for controlling the flow rate of water pumped about the water flow loop 29 by the pump 38. The control device 46 controls 25 the flow rate of water pumped about the water flow loop 29 at least partially dependent upon the temperature of water 36 cooled in the cooling tower 14. The control device 46 enables any surplus cooling of water in the cooling tower 14 to be used to condense at least some of the moisture from the hot, moist air 12 exiting the cooling tower 14. In this regard, some of the excessively cooled 30 water in the cooling tower 14 is circulated through the heat exchanger 16, whereupon it is heated (during the process of cooling the warm, moist air 12) and then returned to the water 36 cooled in the cooling tower 14. The control device includes a thermostat (not illustrated).

WO 2009/117777 PCT/AU2009/000347 8 The control device 46 (or, more particularly, the thermostat) includes a water temperature sensor 48 for mounting in the water cooled 36 in the cooling tower 14. The sensor 48 is illustrated as being mounted in the water flow loop 29 upstream of the water inlet port 26. However, it is to be appreciated that the 5 sensor 48 may be mounted at any other location suitable for sensing the temperature of water 36 cooled by the cooling tower 14, such as directly within the bottom of the cooling tower 14. The thermostat is operably connected to the sensor 48. 10 The control device 46 includes an operator or automated interface 50. The interface 50 includes a temperature selector for manually selecting a desired temperature of water 36 cooled in the cooling tower 14. The control device 46 regulates the temperature of the water 36 in the bottom of the cooling tower 14. In this regard, the temperature selector is operably connected to the pump 15 38 to generate a flowrate of water about the water flow loop 29 dependent upon, for example, any difference between the temperature of water 36 cooled in the cooling tower 14 sensed by the temperature sensor 48 and the desired temperature of water 36 cooled in the cooling tower 14. If the temperature of water 36 cooled in the cooling tower 14 is lower than required (or desired) then 20 water 36 cooled in the cooling tower 14 is directed through the heat exchanger 16 to cool the warm, moist air 12 exiting the cooling tower 14 to condense at least some of the warm, moist air 12 in order to reclaim water from the warm moist air. The water is heated on passing through the heat exchanger 16 and is returned to the water 36 at an elevated temperature. The overall rise in the 25 temperature of the water 36 will be dependent, in part, on the flow rate of water about the water flow loop 29 generated by the control device 46 and pump 38. Although not illustrated, the air exiting the heat exchanger air outlet port 22 need not be directed to or expelled to the atmosphere. Instead, this air (which 30 has been cooled on passing through the heat exchanger 16) may be directed back to the cooling tower 14 via a cooling tower air inlet (not illustrated) to assist in cooling the heated water entering the cooling tower 14. In this regard, a return section (not illustrated) for returning air exiting the air outlet port 22 to an air inlet of the cooling tower 14 may be provided.

WO 2009/117777 PCT/AU2009/000347 9 The flue 30 and return section (not illustrated) may be at least partially integrated. 5 If desired, part of the cooled air exiting the heat exchanger 16 may be directed to the atmosphere and part of the cooled air returned to the cooling tower 14. An arrangement may be provided for altering the ratio of air directed to the atmosphere to air returned to the cooling tower. In such an arrangement, the flue 30, return section and exhaust section 40 may be at least partially 10 integrated. The device 10 may be retro-fitted to existing cooling towers, or may be incorporated into new cooling towers. Thus, it is to be appreciated that the invention relates not only to the device 10, but also to a cooling tower (for 15 example, cooling tower 14) including a device 10 of the type broadly described above. The device provides at least two possible modes of operation. First, the control device 46 may be manually set at installation to pre-select a desired 20 temperature (or range of temperatures) of cooled water 36 in the cooling tower. The control device may automatically factor in extraneous factors such as the ambient air temperature, so as to adjust the temperature of the water 36 in line with changes in ambient temperature. In this way, the control device 46 enables the building's air-conditioning unit to operate at a satisfactory level of 25 performance for a given ambient air temperature. A second mode of operation may include use of the interface 50 to select a desired (temporary or permanent) temperature of the cooled water 36. The device 10 is configured such that, in use, it directs warm, moist air along 30 the air flow path 18 of the heat exchanger 16 extending between the air inlet port 20 and the air outlet port 22. If the temperature of water 36 cooled in the cooling tower 14 is as desired then no water will flow about the water flow loop 29.

WO 2009/117777 PCT/AU2009/000347 10 If, however, the temperature of water 36 cooled in the cooling tower 14 is lower than required (or desired) then the control device 46 activates the pump 38 so as to pump a portion of the water 36 cooled in the cooling tower 14 about the 5 water flow loop 29 extending from water 36 cooled in the cooling tower 14, along the water flow path 24 of the heat exchanger 16 and back to the water 36 cooled in the cooling tower 14. The cooled water entering the heat exchanger 16 causes the warm, moist air 12 to cool, such that at least some of the moisture in the warm, moist air 12 condenses to produce clean water, 10 which flows from the heat exchanger 16 for collection to be utilized for any desired purpose. The (now) heated water flowing about the water flow loop 29 is returned from the heat exchanger to the water 36 in the bottom of the cooling tower 14 to 15 produce an overall increase in the temperature of the water 36. This process continues until such time as the temperature of the water 36 in the bottom of the cooling tower 14 is increased to the desired level. It is to be appreciated that the control device 46 controls the flow rate of water 20 pumped about the water flow loop 29 dependent upon the difference between the actual temperature of the water 36 in the bottom of the cooling tower 14 compared to the desired temperature of the water. In this way, the control device 46 regulates the flow rate of the water generated by the pump 38 to, in turn, regulate to temperature of the water 36. Any flow rate of water about the 25 water flow loop 29 causes cooling of the moist air stream. Cooling this air has the tendency to cause moisture within the warm, moist air 12 flowing through the heat exchanger 16 to condense, and be collected downstream of the air outlet port 22 in the receptacle 42. 30 Again, the device 10 may include a means for directing air downstream of the air outlet port 22 to the atmosphere or back to an air inlet of the cooling tower 14. The air downstream of the air outlet port 22 may also be part directed to the atmosphere and part directed to a cooling tower air inlet.

WO 2009/117777 PCT/AU2009/000347 11 It is to be appreciated that the device 10 may be used in conjunction with or integrated into a cooling tower of any practical type and need not be of the cooling tower 14 type illustrated. 5 It is to be appreciated that the specific design of the heat exchanger 16 may be altered from that broadly described herein. Advantageously, the device 10 enables the at least partial utilization of energy used to excessively cool water in cooling towers. Moreover the device 10 10 enables this energy to be utilised to produce clean, fresh water, which may be used for any suitable purpose. The invention has been described in terms of the device 10 being used in conjunction with a cooling tower 14. However, the device 10 may be used with 15 any other arrangement in which it may be desired to utilize energy used to excessively cool water or any other fluid. Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the construction and arrangement of the parts 20 previously described without departing from the spirit or ambit of this invention.

Claims

1. A device for reclaiming water from moist air discharged from a cooling tower, the device including: 5 a heat exchanger including an air flow path extending between an air inlet port and an air outlet port, and a water flow path extending between a water inlet port and a water outlet port; the heat exchanger configured for, in use: mounting the air inlet port at least partially in a flow path of air 10 discharged from the cooling tower to generate a flow of moist air through the heat exchanger along the air flow path; fluidly connecting the water inlet port to the water cooled in the cooling tower; and fluidly connecting the water outlet port to the water cooled in the cooling tower; 15 a pump for pumping water about a water flow loop extending from water cooled in the cooling tower, through the heat exchanger along the water flow path from the water inlet port to the water outlet port, and from the water outlet port back to the water cooled in the cooling tower;and a water collection device for mounting downstream of the air outlet port 20 for collecting water condensed from moist air flowing along the air flow path.

2. A device according to claim 1, including a control device for controlling the flow rate of water pumped about the water flow loop by the pump, the control device controlling the flow rate of water pumped about the water flow 25 loop at least partially dependent upon the temperature of water cooled in the cooling tower;

3. A device according to claim 2, wherein the control device includes a water temperature sensor for mounting in the water cooled in the cooling 30 tower.

4. A device according to claim 3, wherein the water temperature sensor is configured for mounting in cooled water stored within the cooling tower, or in the water flow loop upstream of the water inlet port. WO 2009/117777 PCT/AU2009/000347 13

5. A device according to any one of the preceding claims, including a flue, the flue including an inlet for receiving air discharged from the cooling tower and an outlet for discharging air into the air inlet port of the heat exchanger. 5

6. A device according to any one of the preceding claims, including an exhaust section for discharging air exiting the air outlet port to the atmosphere.

7. A device when dependent directly or indirectly on claims 5 and 6, wherein the flue and exhaust section are at least partially integrated. 10

8. A device according to any one of the preceding claims, including a return section for returning air exiting the air outlet port to an air inlet of the cooling tower. 15

9. A device when dependent directly or indirectly on claims 5 and 8, wherein the flue and return section are at least partially integrated.

10. A device according to any one of the preceding claims when dependent directly or indirectly on claim 3, including an interface, the interface including a 20 temperature selector for selecting a desired temperature of water cooled in the cooling tower, the temperature selector operably connected to the pump to generate a flow rate of water about the water flow loop dependent upon any difference between the temperature of water cooled in the cooling tower sensed by the temperature sensor and a desired temperature of water cooled 25 in the cooling tower.

11. A device according to any one of the preceding claims, wherein the pump is an electrically operated pump. 30

12. A cooling tower including a device according to any one of the preceding claims.

13. A method of reclaiming water from moist air discharged from a cooling tower, the method including: WO 2009/117777 PCT/AU2009/000347 14 directing air along an air flow path of a heat exchanger extending between an air inlet port and an air outlet port; pumping water about a water flow loop extending from water cooled in the cooling tower, along a water flow path of the heat exchanger extending 5 between a water inlet port and a water outlet port, and from the water outlet port back to the water cooled in the cooling tower; and collecting water downstream of the air outlet port condensed from moist air flowing along the air flow path. 10

14. A method according to claim 13, including controlling the flow rate of water pumped about the water flow loop at least partially dependent upon the temperature of water cooled in the cooling tower.

15. A method according to claim 13 or 14, including directing air 15 downstream of the air outlet port to the atmosphere

16. A method according to claim 13, 14 or 15, including directing air downstream of the air outlet port to a cooling tower air inlet. 20

17. A method according to any one of claims 13 to 16, including the step of inputting into a control device a desired temperature of water cooled in the cooling tower.

18. A method according to claim 17, wherein the flow rate of water pumped 25 about the water flow loop is controlled by the control device.

19. A device substantially as herein described and illustrated.

20. A cooling tower and device substantially as herein described and 30 illustrated.

21. A method of using a device substantially as herein described and illustrated.