I AUSTRALIA - V FB RICE & CO Patent and Trade Mark Attorneys Patents Act 1990 IF Technologies Pty Ltd COMPLETE SPECIFICATION Invention Title: Evaporation inhibitor application The invention is described in the following statement: 2 The present disclosure relates generally to improvements in the field of evaporation inhibitor application and, more particularly to an evaporation inhibitor application system. The presently disclosed system has been developed primarily for controlling 5 evaporation rate in water storage reservoirs. However, it will be appreciated that the present disclosure may also find application in controlling evaporation rate on any water surface. Examples of other applications include controlling evaporation from sewage/wastewater treatment ponds, tailings dams (mining), natural water bodies and open channels, both natural and constructed (such as irrigation water distribution 10 channels). The loss of water from reservoirs through evaporation is a significant problem. To address this problem, it is known that application of an evaporation inhibiting material over the surface of a reservoir can suppress evaporation. Examples of known 15 materials which will generate an evaporation inhibiting layer include, but are not limited to the monolayer forming chemicals hexadecanol and octadecanol. Performance of a monolayer on a reservoir relies on, amongst other factors, the monolayer staying in position and not being degraded. However, many monolayer forming materials are susceptible to degradation by virtue of being consumed by 20 microbes in the water in the reservoir or by volatisation. Also, monolayers are often blown out of position on the reservoir surface by wind, which results in significant portions of the reservoir surface being exposed and, thereby, reduction or loss of evaporation suppression. Known monolayer application systems dispense monolayer chemicals in 25 predetermined dosage amounts and at predetermined time intervals. Accordingly, monolayer chemical is dispensed regardless of prevailing weather conditions and regardless of the present condition of the monolayer on the water storage reservoir. As a result, monolayer chemicals can be applied when there is no need to do so, resulting in wastage, or can be withheld until the predetermined time interval has passed, 30 resulting in sub-optimal evaporation control. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the 35 field relevant to the present invention as it existed before the priority date of each claim of this application.
3 Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 5 In a broad aspect, the present disclosure provides a system for applying an evaporation inhibitor to a reservoir, the system comprising: an array of applicators positioned at spaced apart locations around the reservoir for applying the evaporation inhibitor; 10 a coordinator unit for receiving information on the environment surrounding the applicators and controlling operation of the applicators based on the information. Each applicator may include an onboard controller controlled by the coordinator unit. The array of applicators may include shore-based applicators and buoyant applicators. The buoyant applicators may be anchored to control their position on the 15 reservoir. The buoyant applicators may be anchored by a deadweight attached to a tensioned self-adjusting mooring line, with a submerged buoy providing a resistant force to tension the mooring line. Each of the applicators may include a solar panel and a battery for storing energy generated by the solar panel. Each applicator may include a hopper for storing a quantity of evaporation inhibitor. The hopper may have a capacity 20 of greater than 5L, greater than IOL, or greater than 20L. The evaporation inhibitor may be stored in liquid, granular solid, or tablet form and may be combined with reservoir water inside the hopper/applicator prior to dispensing. Each applicator may include a pump powered by the battery for dispensing the evaporation inhibitor. Each buoyant applicator may comprise a housing connected to one or more floats, with weather 25 sensitive components of the applicator being located inside the housing. Each of the applicators may be independently controllable by the coordinator unit via the respective controller. The information on the environment surrounding the applicators may include weather information from a weather monitoring station and/or reservoir water condition information from a reservoir water condition monitoring 30 device. The coordinator unit may control the applicators in real-time based on prevailing weather conditions as indicated by the weather monitoring station and/or on reservoir water condition information indicated by the reservoir water condition monitoring device. The coordinator unit may control a rate and frequency of evaporation inhibitor application from each applicator. The coordinator unit may 35 analyse the weather information from the weather station and/or reservoir water condition information from the reservoir water condition monitoring device, apply 4 algorithms to the weather information and/or water condition information, and apply decision support rules to calculate an instantaneous evaporator inhibitor application rate for each applicator. The coordinator unit may be adapted to adjust the evaporation inhibitor application rate of each applicator to adjust for one or more of the applicators 5 being inoperative, such as due to having a flat battery or being empty of evaporation inhibitor. The coordinator unit may record a timestamp and duration of each application of evaporation inhibitor performed by each applicator. The coordinator unit may communicate with the applicators and/or weather station and/or water condition monitoring device wirelessly. 10 The weather station may be associated with sensors for measuring one or more local weather variables selected from the group consisting of: evaporative demand, air temperature, solar radiation, relative humidity, surface water temperature of the reservoir relative to ambient air temperature, wind speed and direction, rainfall and rainfall rate. In this group, evaporative demand determines if evaporation inhibitor 15 application is economically justified; wind speed and direction influences the speed at which evaporation inhibitor is removed from the water surface and the direction it is pushed, hence the required replenishment/re-application rate to be applied at an up wind shore; relative temperature adjacent to the reservoir water surface affects vertical stability of the reservoir water surface layers, which impacts the performance of the 20 evaporation inhibitor; and rainfall causes degradation of a film of evaporation inhibitor on the reservoir water surface and also disperses the film via mixing into the water body, which decreases coverage. The coordinator unit may receive rainfall information from the weather station at a frequency of less than 30 minutes, less than 15 minutes, or around I minute. If rainfall is detected, the weather station is adapted to send an 25 immediate signal to the coordinator unit. The coordinator unit may receive information on other local weather variables from the weather station at intervals of less than 1 hour, less than 30 minutes, or around 15 minutes. The weather station may communicate with the sensors wirelessly. The weather station may measure the one or more local weather variables at intervals of less than 24 hour intervals, less than 3 hour 30 intervals, less than I hour intervals, less than 15 minute intervals, or at around 1 minute intervals. A water level meter for measuring a water level in the reservoir may be associated with the coordinator unit. The water level meter may comprise a seepage and evaporation meter. The coordinator unit may receive water level information from 35 the water level meter at intervals of less than 12 hours, less than 6 hours, or around 1 hour. The water level meter may measure the water level in the reservoir at less than 24 5 hour intervals, less than 3 hour intervals, less than 1 hour intervals, less than 15 minute intervals, or at around 1 minute intervals. Evaporation inhibitor dosing decisions may be determined by a set of hierarchical rules in the form of an algorithm for real-time calculation of optimal 5 dosage rate. The decision to apply evaporation inhibitor may be determined by the following steps: Step 1: The wind speed and direction being continuously checked to determine the rate and direction of film drift and hence the amount of water surface covered by a layer of the evaporation inhibitor. When coverage of the evaporation inhibitor drops below a set 10 minimum, dosing decisions may be effected. Step 2: Determine if evaporation rate is sufficiently high enough to justify application of evaporation inhibitor. If evaporation rate is not high enough, then stop. Step 3: Determine if there is a storm event with high winds and/or rainfall expected and when it is predicted to reach the water storage reservoir. This information may be 15 assessed in relation to the evaporation rate to determine if it is economically justified to apply evaporation inhibitor before the storm event begins. If evaporation inhibitor application is justified, or there is no storm event predicted, the next decision may be effected. Step 4: If rainfall is detected wait (i.e. do not proceed to Step 5) until rain has stopped; 20 then loop back to Step 2 and continue. However, if no rainfall is detected, then move to the next decision. Step 5: Check if wind speed is below a nominated threshold value, then determine a required application rate of evaporation inhibitor, with regard to expected drift of evaporation inhibitor on the reservoir water surface due to the wind, to maintain an 25 effective cover of evaporation inhibitor on the surface of the reservoir. Step 6: Check wind direction to determine an expected direction of drift of evaporation inhibitor on the reservoir water surface due to the wind. This information may be used to inform which applicators to use to apply evaporation inhibitor based on prevailing wind direction. Once evaporation inhibitor has been applied based on prevailing wind 30 direction by the appropriate applicators, the dosing decisions process may loop back to Step 1 and repeat. An embodiment of a system for applying an evaporation inhibitor to a reservoir according to the present disclosure will now be described, by way of example only, 35 with reference to the accompanying drawings, in which: 6 Fig. I is a schematic view of an embodiment of a system for applying an evaporation inhibitor to a reservoir according to the present disclosure; Fig. 2 is a schematic view of an embodiment of an evaporation inhibitor applicator for use in the system of Fig. 1; 5 Fig. 3 is a top perspective view of an embodiment of an evaporation inhibitor applicator for use in the system of Fig. 1; Fig. 4 is a bottom perspective view of the applicator of Fig. 3; Fig. 5 is an internal view of the applicator of Fig. 3; Fig. 6 is a schematic view of a mooring arrangement for the applicator of Fig. 3; 10 Fig. 7 shows an embodiment of an arrangement for shore-based applicators; and Fig. 8 is a flow chart of decision support rules for the system of Fig. 1. Referring to the drawings, there is shown a system 10 for applying an evaporation inhibitor to a reservoir 100. The system comprises an array of shore-based 15 12 and buoyant evaporation inhibitor applicators 14 positioned at spaced apart locations around the reservoir. A weather monitoring station 16 is associated with the applicators via a coordinator unit 18, which receives weather information from the weather monitoring station 16 and controls operation of the applicators 12, 14 based on information on the environment surrounding the applicators 12, 14, including the 20 weather information from the weather monitoring station 16. However, the coordinator unit 18 also controls operation of the applicators 12, 14 based on information from a reservoir water condition monitoring device 19. The water condition monitoring device may, for example, supply the coordinator unit 18 with information on the reservoir water temperature and/or evaporation rate. 25 The coordinator unit 18 includes a circuit board with a microprocessor and/or microcontroller, a radio modem, a data modem for remote communications and a LCD display for inputs. Each applicator 12, 14 includes an onboard controller 20 controlled by the coordinator unit 18 via wireless communication with the coordinator unit. The controller 20 also includes a circuit board 20a with a microprocessor and/or 30 microcontroller 20b, a radio modem 20c, and a LCD display and external computer interface. As shown in Fig. 6, each of the buoyant applicators 14 are anchored to control their position on the reservoir. The buoyant applicators 14 are anchored by a 20kg deadweight 22 attached to a tensioned self-adjusting mooring line 24, with a submerged 35 buoy, in the form of a fully-sealed empty 20L container 26, providing a resistant force to tension the mooring line 24.
7 As shown in Figs. 2-5, each of the applicators 12, 14 includes a lOW polycrystalline solar panel assembly 28 and a sealed lead-acid battery 30 for storing energy generated by the solar panel. Each applicator 12, 14 also includes a polypropylene hopper 32 for storing a quantity of liquid, granular or tablet form 5 evaporation inhibitor. When a liquid form evaporation inhibitor, such as cetyl alcohol or stearyl alcohol, is used, a hopper 32 with a capacity of greater than 20L is provided. Each applicator 12, 14 includes a 12V peristaltic metering pump 34 powered by the battery 30 for dispensing the evaporation inhibitor from the hopper 32 into the reservoir under the control of the coordinator unit 18 via the controller 20. The battery 30 10 supplies a IOV voltage to the pump 34, with the voltage being regulated by voltage regulators 36. Each buoyant applicator 14 comprises a sheet-metal or plastic housing 38 around which is provided several foam floats 40, with weather sensitive components of the applicator 14, such as the controller 20, being located inside the housing 38. The 15 housing 38 includes a hinged lid 42 to facilitate easy access to internal components of the applicator 14 for servicing, replacement, repair, or modification. An inlet for a fill line 43 for topping up the amount of evaporation inhibitor in the hopper 32 is also located inside the housing 38. The shore-based applicators 12 may have a similar housing 38, with the floats being omitted, or may be of alternative design according to 20 the evaporation inhibiting material being dispensed. An embodiment of an arrangement for the shore-based applicators 12 is shown in Fig. 7. This arrangement includes a reservoir 12a, piping 12b, pump 12c, pressure sensors 12d, directional solenoid valve 12e, pressure relief valves 12f, floating platform 12g, diaphragm valve 12g, nozzle 12h and floating platform 12i. The arrangement may 25 be modified as required dependant on the specific evaporation inhibiting material being dispensed. Each of the applicators 12, 14 is independently wirelessly controllable by the coordinator unit 18 via the respective controller 20. The coordinator unit 18 controls the applicators 12, 14 in real-time based on prevailing weather conditions as indicated 30 by the weather monitoring station 16. The coordinator unit 18 controls a rate and frequency of evaporation inhibitor application from each applicator 12, 14 via the associated pump 34. The coordinator unit 18 analyses the weather information from the weather station 16, applies algorithms to the weather information and applies decision support rules to calculate an instantaneous evaporator inhibitor application rate for each 35 applicator 12, 14. The decision support rules are discussed in more detail below with reference to Fig. 8. The coordinator unit 18 is adapted to adjust the evaporation 8 inhibitor application rate of each applicator 12, 14 to adjust for one or more of the applicators being inoperative, such as due to having a flat battery 30 or being empty of evaporation inhibitor. The coordinator unit 18 records a timestamp and duration of each application of evaporation inhibitor performed by each applicator 12, 14 to verify each 5 application of evaporation inhibitor and facilitate determining storage reservoir volume. The weather station 16 is associated with sensors for measuring local weather variables including: evaporative demand (i.e. the combination of solar radiation, humidity deficit and wind speed), air temperature, relative humidity, surface water temperature of the reservoir relative to ambient air temperature, wind speed and 10 direction, rainfall and rainfall rate. Evaporative demand determines if evaporation inhibitor application is economically justified; wind speed and direction influences the speed at which evaporation inhibitor is removed from the water surface and the direction it is pushed, hence the required replenishment/re-application rate to be applied at an up-wind shore; relative temperature adjacent to the reservoir water surface affects 15 vertical stability of the reservoir water surface layers, which impacts the performance of the evaporation inhibitor; and rainfall causes degradation of a film of evaporation inhibitor on the reservoir water surface and also disperses the film via mixing into the water body, which decreases coverage. The weather station 16 automatically averages logged weather information 20 daily, hourly, every fifteen minutes and every minute. The weather station 16 has a wireless integrator for interrogating, downloading and sending the required weather information to the coordinator unit 18. An onboard controller is programmed to interrogate the weather station 16 every minute for rainfall, and if rainfall is detected a warning is immediately sent to the coordinator unit 18. For all other climatic data, the 25 weather station 16 is interrogated only every fifteen minutes. This data is then sent to the coordinator unit 18 for analysis. A seepage and evaporation meter 44 wirelessly associated with the coordinator unit 18 is provided for measuring a water level in the reservoir 100. Changes in water depth are recorded every minute and averaged over fifteen minute intervals. This 30 averaged data is then sent to the coordinator unit 18 every hour for analysis. Evaporation inhibitor dosing decisions made by the system 10 are determined by a set of hierarchical rules in the form of an algorithm for real-time calculation of optimal dosage rate. As shown in Fig. 8, the decision to apply evaporation inhibitor is determined by the following steps: 35 Step 1: The wind speed and direction being continuously checked to determine the rate and direction of film drift and hence the amount of the reservoir's water 9 surface covered by a layer of the evaporation inhibitor. When coverage of the evaporation inhibitor drops below a set minimum, dosing decisions are effected. Step 2: Determine if evaporation rate is sufficiently high enough to justify application of evaporation inhibitor. If evaporation rate is not high enough, then 5 stop. Step 3: Determine if there is a storm event with high winds and/or rainfall expected and when it is predicted to reach the water storage reservoir. This information is then assessed in relation to the evaporation rate to determine if it is economically justified to apply evaporation inhibitor before the storm event 10 begins. If evaporation inhibitor application is justified, or there is no storm event predicted, the next decision is effected. Step 4: If rainfall is detected wait (i.e. do not proceed to Step 5) until rain has stopped; then loop back to Step 2 and continue. However, if no rainfall is detected, then move to the next decision. 15 Step 5: Check if wind speed is below a nominated threshold value, then determine a required application rate of evaporation inhibitor, with regard to expected drift of evaporation inhibitor on the reservoir water surface due to the wind, to maintain an effective cover of evaporation inhibitor on the surface of the reservoir. 20 Step 6: Check wind direction to determine an expected direction of drift of evaporation inhibitor on the reservoir water surface due to the wind. This information is then used to inform which applicators to use to apply evaporation inhibitor based on prevailing wind direction. Once evaporation inhibitor has been applied based on prevailing wind direction by the appropriate applicators, 25 the dosing decisions process loop back to Step I and repeat. It will be appreciated that the illustrated system 10 provides significant advantages over the prior art by ensuring that evaporation inhibitor is only applied when necessary, thereby reducing wastage. Moreover, the system 10 ensures that 30 evaporation inhibitor is applied on-demand, thereby more effectively suppressing evaporation compared to prior art systems, which dose at predetermined intervals regardless of demand.
10 It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the specific embodiments described above, with reference to the drawings, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all 5 respects as illustrative and not restrictive. Examples of possible modifications include, but are not limited to: e the buoyant applicators 14 including a propulsion system for repositioning of the applicators 14 on the reservoir 100. In such alternative embodiments, the buoyant applicators 14 may include a Global Positioning System in 10 wireless communication with the coordinator unit 18, such that the coordinator unit may control the propulsion system to reposition the applicators 14 and/or take account of the current positions of the applicators when making dosing decisions; e the weather monitoring station may include sensors for sensing weather 15 variables adjacent the applicators 12, 14 or may use more remote sensors and/or historical weather data, or data from a combination of such sources of weather information; e the applicators 12, 14 may apply a material other than an evaporation inhibitor; and/or 20 0 the positions of the floating actuators 14 may be controlled by a containment grid extending over the reservoir 100 rather than by the tethering arrangement shown in Fig. 6. Such a containment grid may also assist in controlling movement of the evaporation inhibiting layer due to wind.