cooling tower

Abstract

In one aspect, a cooling tower system is provided that includes an evaporative heat exchanger, a sensor configured to detect a parameter of evaporative liquid distributed to the evaporative heat exchanger, and an evaporative liquid treatment system. The cooling tower system also includes a controller having a normal operating mode in which the controller operates the evaporative liquid treatment system to treat the evaporative liquid based at least in part on a determination of insufficient evaporative liquid quality based on the parameter of the evaporative liquid. The controller has a failsafe operating mode in which the controller changes operation of the cooling tower upon a determination that operation of the evaporative liquid treatment system cannot remedy the insufficient evaporative liquid quality.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 023,467, filed May 12, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to cooling towers, and more specifically, to control systems for cooling towers. Background Technology

[0004] Cooling towers typically distribute evaporative liquids, such as water, onto evaporative heat exchangers. Operating a cooling tower usually involves using water treatment specialists to design and implement its water treatment system. These systems typically require a variety of chemicals to control biological growth, corrosion, scaling, and fouling, as well as to minimize water usage. This can be expensive, time-consuming, and burdensome for small facilities with few or no on-site maintenance personnel, especially in areas with challenging water treatment requirements, such as large urban areas. Furthermore, cooling towers may continue operating in environments with high microbial content and / or corrosive water that could damage the tower or the environment, even when alarms are triggered, if any water quality parameter exceeds specified tolerance levels or the measuring sensor malfunctions. Summary of the Invention

[0005] In one aspect of this disclosure, a cooling tower system is provided, comprising a cooling tower and a controller operatively coupled to the cooling tower. The cooling tower includes an evaporative heat exchanger and is operable to distribute evaporative liquid onto the evaporative heat exchanger. The cooling tower includes sensors configured to detect parameters of the evaporative liquid and an evaporative liquid handling system.

[0006] In one embodiment, the cooling tower is an open-circuit direct evaporative cooling tower and the evaporative heat exchanger includes packing. The evaporating liquid includes process fluids received by the cooling tower from a building or industrial process. The process fluid can be water or a mixture of water (e.g., water and ethylene glycol). In another embodiment, the cooling tower is a closed-circuit indirect evaporative cooling tower and the evaporative heat exchanger includes an indirect evaporative heat exchanger comprising serpentine tubes, plates, and / or "fins" for receiving process fluids. As an example, the evaporating liquid in a closed-circuit indirect evaporative cooling tower can be water. The cooling tower distributes water to the indirect evaporative heat exchanger.

[0007] The controller has a normal operating mode in which the controller operates the evaporative liquid treatment system to treat the evaporative liquid when the evaporative liquid quality is determined to be deficient based at least in part on a parameter of the evaporative liquid. The controller also includes a failsafe operating mode in which the controller alters operation of the cooling tower when it is determined that operation of the evaporative liquid treatment system cannot remedy the evaporative liquid quality deficiency. In this way, the cooling tower system can continue to operate in a safe manner despite the evaporative liquid quality deficiency until the system is serviced. The controller operates the cooling tower in the failsafe operating mode to meet a requested cooling load while operating in a safe manner. If the cooling tower is unable to meet the requested cooling load, the controller operates the cooling tower in the failsafe operating mode to provide the maximum cooling capacity possible while still operating in a safe manner.

[0008] In one embodiment, the cooling tower can operate in multiple modes, including a wet mode and a dry mode. The controller allows the cooling tower to operate in the wet mode and the dry mode in the normal operating mode. The controller avoids operating the cooling tower in the wet mode in the failsafe operating mode. The cooling tower can therefore continue to operate in the dry mode to remove heat from the process fluid until the cooling tower is serviced and able to operate in the wet mode in a safe manner.

[0009] In some embodiments, the cooling tower can operate in a dry mode or an adiabatic mode. For example, the cooling tower can have an indirect heat exchanger including coils that receive the process fluid and an adiabatic cooler including an adiabatic pad and a water distribution system. The water distribution system distributes water onto the adiabatic pad to pre-cool air upstream of the coils. In the failsafe operating mode, the controller avoids operating the cooling tower in the adiabatic mode, but can operate the cooling tower in the dry mode.

[0010] Another embodiment of a cooling tower can operate in a dry mode, an adiabatic mode, or a wet mode. The controller avoids operating the cooling tower in the wet mode and the adiabatic mode in the failsafe operating mode. However, the controller can operate the cooling tower in the dry mode.

[0011] In another aspect of the disclosure, a cooling tower is provided that includes an evaporative heat exchanger configured to receive a process fluid and a fan assembly operable to induce an airflow relative to the evaporative heat exchanger. The cooling tower also includes an evaporative liquid distribution system that includes at least one outlet to distribute evaporative liquid onto the evaporative heat exchanger, a sump to collect evaporative liquid from the evaporative heat exchanger, and an evaporative liquid treatment system of the evaporative liquid distribution system. The evaporative liquid treatment system can include, for example, a makeup water supply and a UV lamp assembly operable to treat the makeup water. In one embodiment, the UV lamp assembly is installed in a heat exchange section of the cooling tower or in an evaporative liquid side loop. As another example, the evaporative liquid treatment system includes a chemical treatment system operable to add one or more chemicals to the evaporative liquid.

[0012] The cooling tower also includes a controller and an evaporative liquid sensor configured to detect an evaporative liquid parameter. The controller is configured to operate the evaporative liquid treatment system upon a determination of a deficiency in the quality of the evaporative liquid based at least in part on the evaporative liquid parameter. The controller is also configured to alter operation of the evaporative liquid distribution system to facilitate safe operation of the cooling tower upon a determination that the evaporative liquid treatment system is unable to remedy the deficiency in the quality of the evaporative liquid. Altering operation of the evaporative liquid distribution system allows the cooling tower to continue to operate until the condition that caused the deficiency in the quality of the evaporative liquid is resolved. The condition that caused the deficiency in the quality of the liquid can be, for example, a sensor failure of the cooling tower.

[0013] The disclosure also provides a method of operating a cooling tower. The method includes distributing an evaporative liquid onto an evaporative heat exchanger of the cooling tower and detecting a parameter of the evaporative liquid using a sensor of the cooling tower. The method also includes operating an evaporative liquid treatment system of the cooling tower upon a determination of a deficiency in the quality of the evaporative liquid based at least in part on the evaporative liquid parameter. In addition, the method includes altering operation of the cooling tower to facilitate safe operation of the cooling tower upon a determination that the evaporative liquid treatment system is unable to remedy the deficiency in the quality of the evaporative liquid. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is an elevational view of a cooling tower having an evaporative indirect heat exchanger according to an embodiment of the disclosure.

[0015] Figure 2 is an elevational view of a cooling tower having an evaporative indirect heat exchanger product according to another embodiment of the disclosure.

[0016] Figure 3A 、 Figure 3B and Figure 3C control logic diagram according to a normal mode of operation of a controller of a cooling tower is provided.

[0017] Figure 4A and Figure 4BA control logic diagram is provided according to a failsafe operating mode of a controller of a cooling tower.

[0018] Figure 5A and Figure 5B is a list of optional manual inputs according to examples described herein that a control system of a cooling tower can use in place of automatic sensors for some or all inputs or control points to make operational decisions. DETAILED DESCRIPTION

[0019] In one aspect of the disclosure, a cooling tower and related control system is provided. The control system monitors the condition of the evaporative liquid used by the cooling tower and can make operational changes to reduce the chance of microbial contamination, corrosion, and / or fouling under abnormal conditions while maintaining the cooling tower to operate effectively between water treatment and cooling tower service visits. The evaporative liquid can be water or, in some embodiments, a mixture of water and one or more other liquids such as liquid treatment chemicals. Parameters of the evaporative liquid used by the cooling tower are continuously monitored, including conductivity, biologically active material, biofilm, pH, drift, and float. The control system can also be configured to continuously monitor operating parameters of the cooling tower such as ambient temperature, water spray temperature, sump water level, spray pump operation, sump sweeper pump, side stream UV pump operation, and UV lamp intensity within the sump and / or side stream loop at the time of water makeup to provide inputs to the control algorithm of the control system. For the purposes of this disclosure, the term "cooling tower" refers to, but is not limited to, open circuit direct evaporative cooling towers, closed circuit evaporative liquid coolers, evaporative condensers, adiabatic coolers such as spray and / or mat units, adiabatic condensers, and related components.

[0020] The control system includes a controller having a normal operating mode and a failsafe operating mode. During the normal operating mode, the controller can be configured to periodically automatically clean and then flush the water contacting components of the water tower and / or add water treatment to maintain the cooling tower evaporative liquid within specified tolerance levels to prevent microbial contamination and fouling while striving to conserve water and water treatment chemicals. However, if the evaporative liquid quality is determined to be unsuitable, one or more attempts can be made to automatically resolve the problem. If after a specified number of attempts to correct the evaporative liquid quality problem are performed and the measured evaporative liquid quality parameters remain within an unacceptable range, or if any sensor fails, the controller enters the failsafe mode. The number of attempts can be set by a user, such as three or five attempts, or can be set or adjusted by a remote computer, such as by a server computer that utilizes machine learning to determine the number of attempts based on the operation of similar cooling towers in similar geographic areas, as one example.

[0021] In some embodiments, the fail-safe operating mode can be configured to maintain the cooling tower and the surrounding area or environment in a safer condition until service personnel arrive. The fail-safe mode can involve operating the cooling tower fans, pumps, and other components to limit the possibility of biological contamination leaving the cooling tower in the event of component or sensor failure, or to take additional measures to improve operation as needed, including increasing cleaning and flush cycles, limiting fan speed, increasing water disinfection, or even removing water entirely for dry operation.

[0022] In one embodiment, the fail-safe operating mode such as by operating the cooling tower with cooling tower parameters such as sump pump on / off, pump speed, frequency of cleaning / flush cycles, and / or evaporative liquid treatment chemical usage, keeps the cooling tower from damaging itself. For example, the fail-safe operating mode can involve the controller avoiding running the pump without liquid and / or operating an unbalanced fan. In one example of this, the cooling tower can include a fan assembly with an electronic commutated (EC) motor. The EC motor has a motor controller configured to detect excessive vibration and send an alarm to the cooling tower's controller that the fan has a problem. The controller enters the fail-safe operating mode in response to receiving the alarm from the motor controller. In the fail-safe operating mode, the controller and fan motor controller cooperate to allow the fan to run up to a threshold speed that causes maximum allowed vibration. The controller and fan motor suppress the fan from running beyond the threshold speed. In some examples, the control logic includes a purge and flush cycle in which the cooling tower water is drained and then refilled and recirculated through the sump, water distribution system, and evaporative heat exchanger to sanitize the surfaces with fresh clean water. The purge and flush cycle can be run one or more times while attempting to remedy (or correct) the water quality issue and at the same time keep the cooling tower running. The purge and flush cycle can be configured to reduce the number of microorganisms and solids in the water, suppress solids and contaminants from laying on the bottom and sides of the sump, and limit the possibility of microbial contamination and fouling. Although the subject disclosure is applicable to all cooling towers, cooling towers that use an extremely low volume sump limit the amount of water used during the purge and flush cycle. For example, if the sump is sized to be less than half of the cooling tower footprint, then only half of the water is purged compared to previous cooling towers, which can significantly save water. In addition, in some examples, the control logic can include a dry out cycle that is occasionally run to dry out the water contact surfaces to further reduce the risk of microbial contamination. Removing water from the water contact surfaces kills the microorganisms on the water contact surfaces.

[0023] Figure 1An evaporative heat exchanger cooling tower 10 is shown. The cooling tower 10 has a spray pump 19, a fan motor 25, a fan assembly 26A including a fan 26 and the motor 25, and an evaporative liquid collector such as a water collection system 50. The cooling tower 10 also includes an indirect evaporative heat exchanger such as a serpentine tube heat exchanger 23, an evaporative liquid distribution system such as a water spray distribution system 22, a float remover or mist eliminator 28, water spray nozzles 24, and a sump such as a water spray sump 39. The water spray sump 39 is less than half the footprint of the cooling tower 10, which reduces the amount of water used by the cooling tower 10 when the cooling tower 10 is purged of water. In other embodiments, the sump can be any size up to and including the full size of the footprint of the cooling tower 10.

[0024] Process fluid enters the serpentine tube heat exchanger 23 through the connection 29 and header 30. After passing through the serpentine tube 33, the process fluid passes through the outlet header 32 and then to the connection 31 to exit the serpentine tube heat exchanger 23. In some cases, the flow of process fluid through the connections 29, 31 can be reversed. Specifically, the process fluid can enter the serpentine tube heat exchanger 23 through the connection 31 and exit the serpentine tube heat exchanger 23 through the connection 29.

[0025] During dry operation of the cooling tower 10, the spray pump 19 is turned off and the motor 25 rotates the fan 26 at a speed to achieve a set point required by, for example, an HVAC system, an industrial process system, and / or a user. The fan 26 draws air into the cooling tower 10 and pressurizes the dry chambers 36 and 37, which direct the air upward through the indirect heat exchanger 23 and out through the mist eliminator 28. The serpentine tube heat exchanger 23 shown is a serpentine tube heat exchanger well known in the industry, but the heat exchanger used by the cooling tower 10 can be any type of evaporative heat exchanger, including indirect heat exchangers such as tube and fin heat exchangers and / or plate heat exchangers, and / or direct heat exchangers such as packed heat exchangers.

[0026] During wet operation of the cooling tower 10, the spray pump 19 is on and pumps water from the sump 39 to the distribution pipe 22A and then out of the nozzles 24. As the water exits the nozzles 24, the evaporating water spray forms small water droplets and trickles down and through the indirect heat exchanger 23. The water evaporated during the heat exchange or drained through the sump drain valve 48 to maintain the solids content within acceptable limits is replaced by makeup water through the makeup supply 34A of the makeup float valve assembly 34. The sump drain valve 48 can have a partially open configuration that allows a limited flow of solids-laden water from the sump 39 to drain from the sump 39. The draining of the solids-laden water and the subsequent refilling of the sump 39 with makeup water through the makeup supply 34A acts to reduce the solids in the sump 39. The sump drain valve 48 can have a fully open configuration that allows a greater flow of water to exit the sump 39, and the fully open configuration of the sump drain valve 48 is used to purge the sump 39.

[0027] The cooling tower 10 can include a water level device that actuates a solenoid fill valve to maintain the water in the sump 39 at a set level. Air is drawn in by the fan 26, which is rotated by the motor 25. The speed of the motor 25 is determined by a requested system control set point. Once the water drips from the indirect heat exchanger 23, at least a portion of the water is collected by the water collector 50, and the water is directed away from the fan and toward the sump 39 by the baffle 12. Some of the water that falls from the left side of the indirect heat exchanger 23 falls directly down into the sump 39.

[0028] In the cooling tower 10, a portion of the air travels through the water collector 50 and through the baffle 12, forming a dry zone plenum 36 and a wet zone plenum 37. During wet operation of the cooling tower 10, there is a dry air zone in the plenum 36, and a wet zone is formed in the plenum 37. The combination of the water collector 50 and the sump wall 38 forms a smaller sump 39 that is typically at least half the size of the entire footprint of the cooling tower 10, which allows for easier management of the sump water from a biological and water waste perspective. Other cooling tower configurations, including examples of water collectors, are provided in U.S. Patent No. 10,677,543, which is incorporated herein by reference in its entirety.

[0029] Referring to Figure 2 A cooling tower 20 similar to the cooling tower 10 is provided, where like reference numerals indicate like parts. The cooling tower 20 has a control system 21 including various sensors and a controller 52 for operating the cooling tower 20. The cooling tower 20 includes an ambient temperature sensor 54 configured to sense the outdoor ambient air temperature and a water spray temperature sensor 54A configured to sense the temperature of the water in the water spray distribution system 22. Signals from the ambient temperature sensor 54 and the water spray temperature sensor 54A are sent to the controller 52 for evaluation. The functions of the controller 52 are described in Figures 3A-3C andFigures 4A-4B A logic block diagram of the system is shown in FIG. 1 and discussed further below.

[0030] Cooling tower 20 has an evaporative liquid treatment system 27 that includes a UV lamp 42A mounted on the make-up water line 34 that can be used to reduce the microbial content entering embodiment 20 from make-up line 34. A UV lamp intensity sensor 43A can be used to signal when the lamp is not running or is not running at the minimum allowed intensity and to sound an alarm that the UV lamp 42A needs cleaning or replacement. UV lamps mounted in the sump 39, below the mist eliminator 28, in the wet air zone 37 or in the water spray distribution system 22 can also be used.

[0031] In one embodiment, the evaporative liquid treatment system 27 includes a UV pump 41, a pH sensor 46, a UV lamp 42, a UV lamp sensor 43, a flow verification switch 41C and a conductivity sensor 45. The UV pump 41 is configured to draw side stream water from the sump 39, through the pH sensor 46, through the UV lamp 42, through the flow verification switch 44 and through the conductivity sensor 45 and then back to the sump 39. In another method, the pump 41 is determined to be running by using a differential pressure switch or sensor connected to the pump suction and pump discharge or by a current sensor. The UV side stream pump 41 will run continuously or intermittently to monitor the pH 46, conductivity level 45 and pass sump water 39 through the UV lamp 42 to reduce microbial contamination when water is present in the sump 39 as evidenced by the sump float sensor 47.

[0032] The sump float sensor 47 can be a dual function sensor that also serves as a high water level float sensor to sense that the water is too high and is being wasted. The UV lamp intensity sensor 43 is used to signal when the lamp 42 is not running or is not running at the minimum required intensity and sends a status signal to the controller 52 to be evaluated.

[0033] The pH sensor 46 measures the pH of the sump water. The conductivity sensor 45 measures dissolved solids in the water in the sump 39, such as total dissolved solids. The controller 52 evaluates the conductivity level and the function of the conductivity sensor 45.

[0034] The spray pump flow switch 49 determines if the spray pump 19 is running and alarms the controller 52 of the status of the spray pump 19.

[0035] The floatage sensor 40 located above the mist eliminator 28 senses if the floatage is greater than a threshold or acceptable tolerance level and sends a signal to the control system 52 to be evaluated.

[0036] The plume sensor 55 located above the mist eliminator 28 senses if the plume is greater than an acceptable allowed level and sends a signal to the controller 52 to be evaluated.

[0037] Biofilm sensor 51 detects whether biofilm has formed in the collection tank 39. If biofilm is present, biofilm 51 sends a signal to controller 52 for evaluation. The biofilm sensor can be installed in other moist locations within the cooling tower 20.

[0038] The drain valve 48 of the water collection tank is controlled by the controller 52 and can be fully opened, fully closed, or partially opened as determined by the controller 52, as will be described later.

[0039] The electric emergency shut-off water supply valve 56 is set to open unless a high water level alarm from the water collection tank float sensor 47 detects that water is being wasted, and this situation is assessed by the controller 52.

[0040] Various sensors in cooling tower 20 send data to controller 52 indicating relevant sensed parameters. The sensors may perform edge processing, comparing the sensed parameters to thresholds, ranges, and / or tolerances, and sending data to controller 52 indicating whether the parameter is unacceptable (or acceptable). In other methods, one or more sensors transmit data indicating sensed parameters to controller 52, and controller 52 determines whether the parameter is unacceptable (or acceptable), such as whether the parameter is above / below a threshold, within / outside a range or tolerance, etc.

[0041] for Figure 2 The cooling tower 20 shown is illustrated with an evaporative cooling facility configured as a single inlet with forced ventilation and an indirect heat exchanger, but this should be understood as a non-limiting example. The fan system used can be any type of fan system that moves air through the unit, including but not limited to forced ventilation relative to the spray in a generally counter-current, cross-current, or parallel flow. As a non-limiting example, the fan system can also be a guided ventilation type oriented in a counter-current, parallel, or cross-current manner. For a particular application, the fan location and the direction of air intake and exhaust can differ, and the presented embodiment is not limited.

[0042] Furthermore, motor 25 can be directly connected to fan 26 as shown, or driven by a belt or gear mechanism. The process fluid direction can be reversed to optimize heat exchange and is not limited to the presented embodiment. It should also be understood that the number of loops and tube passes or rows within the indirect heat exchanger 23 is not a limitation on the presented embodiment.

[0043] Furthermore, it should be understood that the type of evaporative heat exchanger used in cooling tower 10 can be selected for specific applications. Although Figure 2 An indirect heat exchanger 23 is shown. This evaporative heat exchanger can also be a direct heat exchanger, such as one with cooling tower fill. The cooling fill may include, for example, a PVC sheet with raised features and / or blocks.

[0044] Accordingly, the cooling towers disclosed herein can utilize various types of evaporative heat exchangers, including but not limited to indirect, direct, a combination of indirect and direct, or adiabatic air coolers, fluid coolers, or condensers.

[0045] The controller 52 includes a processor 52A, a non-transitory computer-readable memory such as memory 52B, and a communication circuit 52C. The memory 52B includes computer-readable instructions such as source code to implement the logic of Figures 3A-3C and Figures 4A-4B The communication circuit 52C is capable of wired and / or wireless communication. In one embodiment, the communication circuit 52C includes a network interface that communicates with one or more networks such as a local wired network (e.g., Ethernet), a local wireless network (e.g., Wi-Fi), a wide area wireless network (e.g., a cellular network), and / or the Internet. Figures 3A-3C and Figures 4A-4B The control logic of and

[0046] The controller 52 has a normal operating mode 300 that utilizes the control logic of Figures 3A-3C and a fail-safe operating mode 400 that utilizes the control logic of Figures 4A-4B When all sensors and facilities are functioning properly and water quality parameters are within the tolerance of the allowable operating range, the controller 52 is in the normal operating mode 300. If an abnormal water condition occurs, such as a parameter of the water falling outside of the acceptable range, the controller 52 and / or a remote computing device determines that the evaporative liquid quality is insufficient. In the normal operating mode, the controller 52 will make several attempts to clear the abnormal condition. Attempts to correct the abnormal water condition can include, for example, a clear and flush cycle, a clean and sanitize cycle, or a combination thereof, as described below. If the measured water quality parameters remain outside of the acceptable range after a prescribed number of attempts to correct the water quality have been performed, or if any sensor fails, the controller 52 switches to the fail-safe mode.

[0047] The fail-safe mode keeps the cooling tower water and the environment in a safer state until service personnel arrive. If the readings of any of the sensors of the cooling tower 20 are not within an acceptable range, or are interpreted by the controller 52 to be in a fault condition, the controller 52 sends a notification such as an alarm to a remote computing device and the controller 52 switches to a fail-safe mode, which is described in further detail with reference to FIG. 4. The controller 52 can send the alarm to, for example, the HVAC system, a server computer, a service provider, and / or a user device. As some examples, the alarm can be in the form of an email, an application notification, and / or an SMS message.

[0048] In one embodiment, the controller 52 assigns different weights to different evaporative liquid parameters and resolves deviations in the evaporative liquid parameters differently. For example, the controller 52 can enter the fail-safe operating mode 400 in response to the controller 52 determining that the biofilm parameter exceeds a threshold. In contrast, the controller 52 can not enter the fail-safe operating mode 400 in response to the controller 52 determining that the pH of the evaporative liquid exceeds a threshold. Instead, the controller 52 communicates a warning about the elevated pH value to a remote device.

[0049] In some embodiments, the controller 52 takes an average of the readings of the sensors of the cooling tower 20 to ensure that the abnormal situation is real before making a decision. The controller 52 can employ historical data of the cooling tower 20 and / or other cooling towers to identify thresholds, ranges, and tolerances for determining whether a current parameter value is unacceptable using machine learning.

[0050] Alternatively or additionally, the controller 52 can compare different evaporative liquid parameters to determine a deficiency in a given evaporative liquid parameter. For example, before initiating the fail-safe operating mode 400 based on an elevated pH level parameter, the controller 52 can consider the elevated pH level parameter based on the biofilm parameter and the chlorine level parameter of the evaporative liquid. If fewer than all three parameters are outside of an acceptable tolerance, the controller 52 can determine that the evaporative liquid parameters are temporarily adequate. Similar readings that occur outside of the tolerance after a set period of time can be a reason for the controller 52 to initiate the fail-safe operating mode 400.

[0051] Referring now to Figures 3A-3C control logic is provided for the normal operating mode 300. The normal operating mode 300 includes the controller 52 receiving 302 a cooling request or call and initiating 304 a normal wet evaporation cycle. The controller 52 checks 306 whether the cooling tower 20 includes a sump heater. If there is a sump heater, then the evaporative facility can typically run wet regardless of the ambient temperature and continue operation 312. If there is no sump heater, then the controller 52 considers the ambient temperature sensed by the temperature sensor 54 at operation 306.

[0052] A customer or operator can input whether the cooling tower 20 can be allowed to operate in the freeze condition, such as via a user interface of an HVAC system operably coupled to the cooling tower 20. On some facilities, if the ambient temperature is below freezing (32 °F), the cooling tower 20 will not operate in the wet mode to eliminate the possibility of freezing, but will operate in the dry mode. When the cooling tower 20 does not have a sump heater and the ambient temperature is below a predetermined temperature, such as 40 °F, the controller 52 sends a low temperature alert 310 to a remote device, such as the HVAC system or a user smartphone. Alternatively or additionally, the controller 52 can monitor the temperature sensor 54A in the spray water line, and as long as the spray water temperature remains above a preset level (typically 45 to 50F), it is safe to operate the cooling tower in the wet mode.

[0053] Referring again to Figure 3A , the controller 52 monitors a wet timer at operation 312 to track how many hours the cooling tower 20 has been operating in the wet mode. One reason to track the time the cooling tower 20 has been operating in the wet mode is because the controller 52 is programmed so that at a selected time interval (a changeable parameter, typically after 24 hours of wet operation), the cooling tower 20 can be operated in a purge and flush cycle to reduce the risk of microbial contamination at a convenient time for the operator of the cooling tower 20.

[0054] The configuration of the unit is to allow the purge and flush cycle without wasting a large amount of water. While the flush cycle can be used for evaporative heat exchange facilities of any size, it is advantageous for some applications to have the sump as small as possible. The sump can be less than half the size of the footprint of the cooling tower to minimize the amount of water used.

[0055] Referring to Figure 2 , the sump 39 is smaller than the footprint of the unit as shown by the wall 38, for example, less than half the size. The purpose of the purge and flush cycle is to treat accumulated solids, debris, contaminants, microorganisms, and biofilm to help keep the tower sump floor and walls clean and reduce microbial contamination. When the controller 52 is in the normal operating mode 300, the controller 52 can perform the purge and flush cycle once a day (or after 24 hours of wet operation). When the controller 52 is operating in the failed safe operating mode 400, the controller 52 will run the purge and flush cycle more frequently because when operating in the failed safe operating mode, the controller 52 has determined that there is an abnormal condition that cannot be corrected in the normal operating mode and the controller 52 has sent a notification that the unit needs service. More details about the operation of the failed safe operating mode are discussed below.

[0056] Referring again to Figure 3AOnce the wet mode is initiated, the controller 52 turns on the makeup water at operation 312 and starts a fill timer. The controller 52 determines 314 whether the sump water has reached a minimum water level as detected by the sump float sensor within a certain period as determined by the fill timer, and if the sump 39 is not filled within a maximum allowable fill time, which can be an adjustable parameter, the controller 52 sends 316 a low sump water alarm. The controller 52 refrains from operating the cooling tower 20 in the wet mode and waits for the makeup assembly to be repaired and the alarm to be reset. However, if the sump float detects that the sump water level is sufficiently high, the controller 52 energizes the misting pump 19 at operation 318 and the misting pump start timer is energized. After the misting pump time period ends, the controller 52 checks 320 whether the sump water has reached a predetermined water level based on the sump float sensor 47. If at operation 320 the sump water has exceeded the predetermined maximum water level, the controller 52 sends 322 a high sump water level alarm.

[0057] The controller 52 determines 324 whether the misting pump 19 is on. This determination 324 can include, for example, checking whether the misting pump switch detects water flowing down the misting pump 19. If the misting pump switch 49 (see Figure 2 ) does not detect water flow, the controller 52 sends 326 a misting pump alarm. In one embodiment, the controller 52 cannot operate in the normal operating mode 300 after one or more alarm communications (e.g., sent 310, 316, 322, 326) until the alarm is cleared and the problem is repaired. The controller 52 operates the cooling tower 20 in the dry mode until the problem is repaired.

[0058] Once the controller 52 determines that the misting pump 19 is running, the controller 52 starts the UV pump 41 at operation 328 and waits for a predetermined time period, such as ten seconds. At the end of the time period, the controller 52 determines 330 whether the UV pump 41 is running, such as by checking whether the UV pump switch detects water flow through the UV side stream circuit 97. If the controller 52 determines 330 that the UV pump is not running, the controller 52 sends 332 a UV pump alarm, turns off the UV lamp, and enters the fail-safe operating mode 400.

[0059] Note that there are different ways to prove that the spray pump or UV pump is pumping, such as a flow switch, a differential pressure switch, and / or a current sensor. Also note that once the sump float switch determines that there is water in the sump 39, in one embodiment, the UV pump will always run to continuously reduce the microbial content in the sump water until the float switch detects a low water level or no water in the sump. This also allows continuous monitoring of all water quality parameters. Once the UV pump flow switch 41C detects water flow in the side stream water loop, the controller 52 checks 334 the intensity sensor of the UV lamp. If the UV lamp loses intensity more than a minimum effective value (e.g., 8%), which means that the lamp needs to be cleaned or is not working properly, the controller 52 sends 336 a UV bulb replacement alert and the controller 52 changes from the normal operating mode 300 to the fail-safe operating mode 400.

[0060] Referring again to Figure 3B , generally, once the controller 52 determines at operation 334 that the UV lamp intensity is acceptable, the controller 52 checks 338 whether the conductivity sensor 51 is operational. If the conductivity sensor 51 is not operational, the controller 52 sends 340 a conductivity alert and enters a fail-safe mode.

[0061] If the conductivity sensor 51 is operational, the controller 52 determines 342 whether the conductivity of the sump water is greater than a predetermined level, such as 1,000 micromhos per centimeter. The conductivity levels used at operations 342 and 346 can be programmed into the controller 52 by the user. Because as water evaporates, the solids contained in the water are left behind, the cooling tower discharge is used to keep the level of dissolved solids within an acceptable range. The evaporative liquid treatment system 27 of the cooling tower 20 can include a chemical treatment system 99 that is primarily responsible for discharging water from the sump 39 in addition to adding chemicals to the water. The chemical treatment system 99 can add solid or liquid chemicals to the water. Example chemicals include chlorine, bromine, halogen tablets, corrosion inhibitors, scale inhibitors, and / or non-oxidizing biocides. The chemical treatment system 99 can include, for example, a floating feeder and / or a brominator with a separate recirculation pump.

[0062] If the discharge function of the chemical treatment system 99 is not operating correctly, the controller 52 in the normal mode operates as a backup control and discharges water from the sump 39 as needed. This helps ensure that the cooling tower can continue to operate without the solids getting out of control until the next service visit. Thus, as an example, the chemical treatment system 99 can turn on the discharge at 1,000 micromhos per centimeter and turn off the discharge at, for example, 800 micromhos per centimeter. This difference can help ensure that a small amount of water is discharged and that makeup water replaces the water that was discharged. Of course, these values can be changed to suit the needs of the installation.

[0063] Continuing the example, the backup conductivity setpoint of controller 52 is set to open the drain at 1200 microsiemens per centimeter and to close the drain at 1000 microsiemens per centimeter, and the next setpoint is set to open at 1500 microsiemens per centimeter and to close at 1000 microsiemens per centimeter. Thus, when controller 52 sees the conductivity of the water cross the 1200 conductivity point, in the normal operating mode, controller 52 performs 344 a drain operation by opening the sump drain valve 48 for a calibrated period of time to prevent the spray pump from shutting down. The open drain valve 48 drains water from the sump 39, and the make-up float valve assembly 34 will automatically fill the sump. Alternatively or additionally, controller 52 can decide to open the drain valve 48 to drain water based on load and / or time of day. In one embodiment, the drain valve 48 can be proportionally controlled to allow a small amount of water to be drained, or a separate drain valve (not shown) can be installed, for example.

[0064] If the conductivity of the water drops below 1,000 microsiemens per centimeter during the normal operating mode, the drain valve 48 will close and controller 52 allows the chemical treatment system 99 to control the drain provided by the sump drain valve 48. However, if the conductivity value continues to rise near the second controller high setpoint, 1500 in this example, in the normal operating mode, controller 52 takes control of the sump drain valve 48 and initiates 348 a purge flush cycle 384 that purges or drains all of the sump water and then refills the sump with water. The purge and flush cycle 384 should immediately bring the solids content below the 1,000 setting, with appropriate differential at each setpoint.

[0065] It should be noted that in some embodiments, the cooling tower 20 includes a sump sweeper system that includes a pump and piping. The sump sweeper system can be run as part of the purge and flush cycle 384 to help agitate the solids and any bioactivity that is to be purged from the cooling tower. If the conductivity is still high after a set amount of purging and flushing, a high conductivity alarm is sent and controller 52 switches to the fail-safe operating mode 400, which will be described below. Also, at operation 338 there is feedback from the conductivity sensor itself. If the feedback is that the conductivity sensor has failed or is not working, a conductivity sensor failure alarm is sent and controller 52 changes the operation of the unit from the normal operating mode to the fail-safe operating mode.

[0066] Referring again to Figure 3B Once the conductivity is within acceptable limits, controller 52 determines 350 whether the biofilm sensor 51 is operational. If not, controller 52 sends 352 a biofilm alarm and enters the fail-safe mode.

[0067] If the biofilm sensor 51 is operable, the controller 52 determines 354 whether any bioactivity or any biofilm is forming in the sump 39. If bioactivity or biofilm is detected, the controller 52 in the normal operating mode initiates 356 a cleaning and flushing cycle 384 that runs to clean the bioactivity or biofilm in the sump water by flushing the sump 39 and associated water contact components. Alternatively or in addition to the cleaning flush cycle 384, the controller 52 can direct an emergency supply of shock chemicals to the cooling tower sump. As an example, if the chemical treatment system 99 provides chlorine or other chemicals to control bacterial growth and the chemicals are depleted or their system fails to add chemicals, the controller 52 in the normal operating mode 300 can act as a back-up system to reduce the risk of microbial contamination by adding emergency chemicals to clean and disinfect in the cooling tower sump 39, or can purify and flush the sump water containing components, or both, until service personnel arrive to fix the abnormal condition. It should be noted that after multiple cleaning and flushing cycles, and after an emergency supply of chemicals is added, if bioactivity or biofilm is still detected, a biofilm alarm is sent and the controller 52 changes from the normal operating mode 300 to the failsafe operating mode 400. Also, at operation 350 there is feedback from the bioactivity and / or biofilm sensor itself. If the feedback is that the sensor has failed or is not working, a biofilm sensor alarm is sent and the controller 52 changes from the normal operating mode 300 to the failsafe operating mode 400.

[0068] Referring again to Figure 3C Once no bioactivity or biofilm above an acceptable set point level is detected, the controller 52 next checks 358 whether the pH sensor 39B is operable. If not, the controller 52 sends 360 a pH sensor alarm and enters the failsafe operating mode 400.

[0069] If the pH sensor 39B is operable, the controller 52 determines 362 whether the pH value in the water is acceptable, such as within a predetermined range. If the pH value is not acceptable, the controller 52 can add emergency back-up chemicals and / or activate 364 a cleaning and flushing cycle 386 depending on the quality of the makeup water and manual input.

[0070] For example, if the incoming makeup water is not within acceptable limits for pH and chemicals need to be added to control the pH level, the manual input recognized by the controller 52 at operation 386 causes the controller 52 to direct the chemical treatment system 99 to add chemicals at operation 396 instead of performing a cleaning and flushing operation 388 to control the pH. Thus, during the normal operating mode, the controller 52 will act as a back-up to the way the chemical treatment system 99 will maintain the pH level.

[0071] If a certain number of purge and flush cycles or addition of chemicals are attempted during the normal operating mode in an attempt to bring the cooling tower water back into an acceptable pH range, the controller 52 sends a pH alarm and activates the fail-safe operating mode 400. Additionally, there is feedback at operation 358 from the pH sensor itself. It should be appreciated that in some embodiments, the unacceptable pH parameter is not sufficient by itself to cause the controller 52 to enter the fail-safe operating mode 400. If the feedback is that the pH sensor has failed or is not working, a pH sensor alarm is sent and the controller 52 changes the controller 52 from the normal operating mode 300 to the fail-safe operating mode 400 at operation 360.

[0072] Reference is made to Figure 3Cfrom the drift sensor 40 and determines 366 whether the drift sensor 40 is functioning properly. The drift sensor 40 is configured to detect whether there is an unacceptable amount of drift. Drift is defined as water droplets or aerosols exiting the cooling tower 20. Since most cooling towers are designed to have minimal amounts of drift, drift can occur in some abnormal situations, such as in extreme wind conditions, when the cooling tower fill is damaged, the cooling tower eliminator is damaged or displaced, or when the water distribution nozzles are displaced or broken. Although these situations are rare, this application describes techniques for controlling the cooling tower 20 during these abnormal situations to limit drift while keeping the cooling tower 20 operational. If the drift sensor 40 detects an unacceptable amount of drift, the controller 52 in normal operating mode will attempt to lower the drift rate to reduce the risk of microbiological contamination of the environment. If the drift rate is not within proper limits and the level of biological activity or biofilm content is also high, the controller 52 can shut down the cooling tower according to manual input until service is performed to prevent microbiological contamination of the surrounding environment. If drift is detected to be too high in normal operating mode, the controller 52 will attempt to correct or lower the drift rate if this is a preference input in the manual data. The controller 52 can also switch to lower fan speeds, shut down the unit, or switch to dry operation according to manual input and system requirements. For example, in a multiple cooling tower installation, if one cooling tower has a drift problem and the other cooling towers can handle the load, it can be decided to shut down the cooling tower and require service. However, if the customer needs to continue operating the cooling tower until service personnel arrive, the controller 52 will decide to lower the fan speed to a level where drift is not known to occur, typically 50% of fan speed, and the controller 52 sends 372 a drift alarm and changes the operation of the unit from normal operating mode to fail-safe operating mode. In addition, there is feedback from the drift sensor 40 itself. If the controller 52 determines 366 that the drift sensor 40 has failed or is not working, the controller 52 changes the operation of the unit from normal operating mode to fail-safe operating mode 400 and sends a drift sensor alarm at operation 368.

[0073] Reference is made to Figure 2The plume sensor 55 is configured to detect, 373, the presence of an unacceptable rate of plume leaving the cooling tower, as some customers might expect. In some applications, plumes are undesirable because they can be interpreted as unsafe conditions; for example, plumes might obstruct visibility at an airport, freeze, or strike surrounding buildings or structures. Therefore, some cooling tower customers request that plumes be limited or completely avoided. Cooling towers used in these applications are typically equipped to reduce plumes. If the plume sensor 55 detects, 373, that the plume is too high, the controller 52 will change unit operating parameters to reduce or eliminate the plume, such as adding heat from waste heat sources or other heat sources. If an unacceptable amount of plume is still detected after adjustments, the controller 52 sends a 375 plume alarm and changes the controller 52 from normal operating mode to fail-safe operating mode. Additionally, there is feedback from the plume sensor 55 itself. If the controller 52 determines that the plume sensor 55 has malfunctioned or is not working, the controller 52 changes from the normal operation mode 300 to the fail-safe operation mode 400 and sends a plume sensor alarm.

[0074] After completing a safety check of the water system in the collection tank and the operation of the cooling tower, controller 52 checks whether cooling tower 20 has exceeded the wet timer setpoint, which is typically set to 8 to 24 wet operating hours under normal conditions. If cooling tower 20 has exceeded the manually input wet operating time period, controller 52 initiates purge and flushing cycle 384. Purge and flushing cycle 384 can be manually set according to user input (see [link to relevant documentation]). Figure 5A and Figure 5B ).

[0075] If no treatment chemicals are added at operation 386, the purge and flush cycle 384 includes controller 52 guiding operation 388. Figure 3B). Operation 388 includes turning off the spray pump, turning off the UV pump, turning off the UV lamp, turning off the makeup water valve 56, turning off the fan motor 25, turning on the sump drain valve 48, and turning on the drain 41 A associated with the UV lamp 42. Operation 388 also includes waiting for a first predetermined time period, such as 30 seconds, and then turning off the drain. Next, the makeup water valve 56 is turned on and the spray pump 19, the UV pump 41, and the sump cleaner pump 39A (if equipped) are turned on. The controller runs a purge cycle and waits for a second predetermined time period, such as 30 seconds, and then initiates a clean cycle again, which includes turning off the spray pump, turning off the UV pump, turning off the UV lamp, turning off the makeup water valve 56, turning off the fan motor 25, turning on the sump drain valve 48, and turning on the drain 41 A associated with the UV lamp 42. The controller 52 waits for a third predetermined time period, such as 30 seconds, and then turns off the sump drain valve 48 and the UV pump drain 41 A. The makeup water valve 56 is turned on and the sump pump 19, the UV pump 41, and the sump cleaner pump 39A are turned on. In some embodiments, the sump cleaner pump 39 is connected to a filter or cyclone separator that has their own purge cycle that can be controlled by the controller 52. Operation 388 ends with the initiation of the operation of the fan 26 and the wet operation of the cooling tower 20.

[0076] If after running the clean and purge cycle 384, any of the conductivity, biofilm, or pH levels are not as determined at operations 390, 392, 394, then one or more alarms are sent and the controller 52 changes from the normal operation mode 300 to the fail-safe operation mode 400 at operations 391, 393, 395. After the clean and purge cycle 384, the controller 52 also looks at the dry run timer and will initiate 380 the dry cycle 382 when the duration of the dry run timer is higher than the manually entered dry run timer time period. The purpose of the dry cycle is to clean the sump water and operate the fan 26 so that the sump 39 is dry for a manually entered specified time period to inhibit microbial contamination, as many microorganisms will die once dry. Once the dry cycle 322 is complete, the system cycles back to the beginning of the normal operation mode 300.

[0077] Another feature of the control logic of the normal operating mode 300 is the ability of the controller 52 to detect when an abnormal condition exists, send an appropriate alarm, and switch from the normal operating mode 300 to the fail-safe operating mode 400. The controller 52 continuously monitors the cooling tower water quality parameters including, but not limited to, at least one of the following: conductivity levels, biological activity or presence of biofilm, pH levels, excessive drift, and cooling tower float. The controller 52 also continuously monitors the following: ambient temperature, spray water temperature, sump water level, spray pump operation, UV pump operation, UV lamp intensity on the make-up and / or bypass loops, conductivity sensors, biofilm detection sensors, pH level sensors, drift sensors, and float detection sensors.

[0078] If one or more of the above-mentioned sensors fail or after attempting to bring the water quality back into an acceptable operating range, such as after adding chemicals or activating a prescribed number of water purge and flush cycles 460, the controller 52 operates in the fail-safe operating mode 400 (see FIG. 4). During the purge and flush cycle operation 464, the cooling tower water is purged and then refilled with clean water, and then the sump, water distribution system, and evaporative heat exchanger are flushed. In some embodiments, after the water has been purged, the chemical treatment system 99 adds chemicals to the newly filled sump water to aid in cleaning, flushing, and disinfecting the components that come into contact with the water. In one embodiment, the fail-safe operating mode 400 increases the frequency of the purge and flush cycles 464 compared to the purge and flush cycles 384 during the normal operating mode 300 to keep the water quality parameters safe until the cooling tower 20 is properly serviced and the alarm is reset.

[0079] For example, in some prior art cooling towers that use a conductivity sensor, the conductivity sensor measures the solids content in the water and the cooling tower opens a drain until the conductivity sensor reads an acceptable value. However, if after a period of time the conductivity does not drop below an acceptable value, or if the solids content continues to rise, a service alarm is opened, but there is no provision to continue to operate the tower under safer conditions until service is complete. To address this problem, and to prevent the solids from running to a level that produces extreme heat exchanger fouling and loss of cooling tower capacity, Figures 3A-3C and Figures 4A-4B The cooling tower 20 and control logic in the Figure 5A and Figure 5Bincludes instructions to shut down the cooling tower 20 in this case. The cooling tower water will then be drained and the cooling tower 20 shut down until service personnel service the cooling tower 20 and reissue the alarm.

[0080] As another example, in some prior art cooling towers that use a pH sensor, the sensor will measure the pH and add chemicals to attempt to maintain a suitable pH level. However, if after a period of time the pH does not reach an acceptable value, there is nothing prescribed to continue to operate the tower under safer conditions until service is completed, other than to open a service alarm. To address this problem and prevent the cooling tower from operating at extremely unsafe and potentially corrosive pH levels, Figures 3A-3C and Figures 4A-4B The cooling tower 20 and control logic in Figure 5A and Figure 5B includes instructions to shut down the cooling tower 20 in this case. The cooling tower water will then be drained and the cooling tower 20 shut down until service personnel service the cooling tower 20 and reissue the alarm.

[0081] In another example of the benefits provided by the cooling tower 20, a contractor can from time to time add very strong acids to the water basin in an attempt to descale the indirect heat exchanger. However, if not managed properly, the cooling tower water can be left at a very corrosive pH level. In this extreme abnormal condition, the controller 52 can be configured to continue to invoke the purge and flush cycles in an attempt to correct the situation, and after a certain number of purge and flush cycle attempts, if the pH level remains outside of safe operating conditions, the controller 52 will send a pH alarm and activate the fail-safe mode. In one approach, the manual input 500 (see Figure 5A and Figure 5B includes instructions to shut down the cooling tower 20 in this case. The cooling tower water will then be drained and the cooling tower 20 shut down until service personnel service the cooling tower 20 and reissue the alarm.

[0082] As another example, in some existing cooling tower applications, the side flow of water from the catch basin with UV lamps is used, or the UV lamps are installed in the water supply line or catch basin, or both. As long as the UV lamps are clean and operating at acceptable intensity levels, they will continue to kill bacteria. However, if the UV lamps become dirty or malfunction, there is no provision for continuing to operate the cooling tower under safer conditions until maintenance is completed, except for issuing a maintenance alarm. To address this issue and reduce microbial contamination, when the UV lamps are not working or require cleaning, [further measures should be taken]. Figures 3A-3C and Figures 4A-4B In the cooling tower 20 and control logic, controller 52 switches to fail-safe operation mode. In fail-safe operation mode, the water collection tank 39 can be cleaned and flushed at a much higher rate and / or antimicrobial chemicals can be added to reduce the chance of microbial contamination until the cooling tower 20 is repaired and the alarm is reset.

[0083] In some embodiments, a user may provide water quality parameters to the controller 52 using a user interface of the cooling tower 20 or a remote device communicating with it. Water quality parameters may include cooling tower conductivity, pH, biological activity, biofilm, suspended matter, and plume. Water quality parameters can be determined through manual instrument testing. Manual input can be considered in the control logic in the same way as water quality parameters are autonomously collected by sensors of the cooling tower 20. Figures 3A-3C and Figures 4A-4B One advantage of the control logic is that it keeps the cooling tower 20 and the environment safe by first attempting to automatically clean the water collection tank 39, and then switching to fail-safe operation mode 400 once any problems that cannot be fixed in normal operation mode 300 are detected.

[0084] As another example, in existing cooling tower applications, the water supply valve or solenoid filler valve may occasionally remain fully open, resulting in excessive water waste. While some existing cooling towers are equipped with high water level alarms, no water-saving measures are specified. In normal operating mode 300 and fail-safe operating mode 400, if a high water level is detected and depends on manual input 500, although alarms are sent at operations 322 and 422, water supply to the cooling tower 20 is also shut off via a separate electrically operated emergency water valve 56. If this configuration is used, dry operation will still be permitted, but with the potential to save water, which would otherwise be continuously discharged from the collection tank 39 via the cooling tower overflow valve.

[0085] like Figure 3AAs shown, during the cleaning and flushing cycle 384, the water supply is shut off, the spray pump 19 is shut off, the UV lamps 42, 42A and UV pump 41 are shut off, the sump drain valve 48 is open, and the UV pump drain pipe 41A is open, allowing all water in the cooling tower 20 to be removed. In operation 388, the controller 52 sets a timer using a time period (e.g., 30 seconds) determined by the controller 52 or input by the user to allow water to be completely drained from the cooling tower. Then, the sump drain valve 48 and the UV pump drain pipe 41A are closed, and the water supply is reopened, allowing clean water to fill the sump 39 and associated piping system. Once a minimum water level is detected in the sump 39, such as when the controller 52 detects that the water supply float valve assembly 34 is closed, the spray pump and UV pump are reopened, allowing clean water to circulate to scrub and clean the surfaces within the sump and the water contact surfaces of the spray distribution system 22 and the serpentine heat exchanger 23, which helps to remove any solids, debris, contaminants and microorganisms that may have accumulated. In another embodiment, the controller 52 detects the minimum water level via an electronic water level sensor.

[0086] In one embodiment, the cooling tower 20 may be equipped with a two-speed or variable-speed spray pump 19. The controller 52 operates the spray pump 19 at a low speed for water recirculation during the wet evaporation mode of the cooling tower 20, and operates it at a high speed during purging and flushing cycles 384, 460. This allows for higher water flow rates and greater scrubbing action during purging and flushing cycles 384, 460. If configured this way, the fan 25 typically stops or operates at a low speed to limit the occurrence of floating debris when the spray pump 19 is running at high speed to flush water-contact components.

[0087] After cleaning and rinsing cycles 384 and 460, water can be used immediately if the water quality is detected to be within acceptable limits or after running for a few minutes. If the water quality is still not within acceptable limits, the water is cleaned again, and the process is restarted. The number of cleaning and rinsing cycles 384 and 460 in the rinsing cycle mode is an adjustable parameter that can be manually set according to environmental conditions and the quality of the makeup water.

[0088] Another feature of the control logic of the normal operating mode 300 is the ability to continue to operate the cooling tower 20 in the wet evaporation mode during the cleaning and flushing cycle 384. This operability is set by a manual input so if the user has selected to keep the cooling tower 20 running during the cleaning and flushing cycle 384, the normal operating mode 300 will keep the fan 25 running because it is important to maintain the liquid set point. When the serpentine heat exchanger 23 begins to dry out, the cleaning and flushing cycle 384 is terminated and the water reservoir is refilled. Stopping the cleaning and flushing cycle 384 after a period of time and before the serpentine heat exchanger 23 is completely dry prevents the evaporation heat exchanger 23 from becoming contaminated. This period of time can be input by the user or determined by the controller 52. The period of time is based on the configuration of the cooling tower 20 and the time required to refill the water reservoir 39.

[0089] Referring now to FIG. 4, the controller 52 failsafe operating mode 400 is activated when any sensor is found to be faulty or when any measured and controlled water quality parameter is outside of the acceptable range and attempts to correct them during the normal operating mode 300 have failed. One purpose of the failsafe operating mode is to keep the cooling tower 20 and the environment safe during the abnormal condition until maintenance is performed on the cooling tower 20.

[0090] Depending on the manual inputs provided to the controller 52, during the failsafe operating mode, the cooling tower 20 can continue to run, can operate with limited capability, can run in a dry mode (if so equipped) or can be shut down.

[0091] Referring again to FIG. 4, once the controller 52 has determined that the failsafe operating mode is required, at call 402 cooling, and more specifically, when the cooling tower 20 needs to run in the wet evaporation state, the controller 52 initiates 404 the failsafe mode wet cycle and checks 406 to see if there is a reservoir heater. If there is a reservoir heater, the evaporation equipment can typically run wet regardless of the ambient temperature, but this is a manual input depending on the cooling tower configuration. If there is no reservoir heater, the controller 52 considers the ambient temperature sensed by the temperature sensor 54.

[0092] If the ambient temperature is below freezing and there is no reservoir heater, the controller 52 sends 410 a low temperature alarm and keeps the cooling tower 20 from running in the wet evaporation mode to eradicate the possibility of freezing. Another option is to monitor the temperature sensor 54A in the spray or outlet water pipe and as long as the water temperature remains above a preset level, typically 45°F to 50°F, it is safe to operate the cooling tower 20 in the wet evaporation mode.

[0093] Referring again to FIG. 4, once the controller 52 will allow the cooling tower to operate in the wet mode, the controller 52 performs operation 412, which includes the controller 52 monitoring a wet timer to track the time that the cooling tower 20 has been operating in the wet evaporative mode. The controller 52 tracks the time that the cooling tower 20 has been operating in the wet evaporative mode because the controller 52 runs purge and flush cycles at selected time intervals (variable parameter), typically after 4 hours of wet operation in the fail-safe operating mode. The purge and flush cycles will occur more frequently in the fail-safe operating mode than in the normal operating mode to keep the cooling tower and the environment safe until maintenance can be performed on the cooling tower 20.

[0094] In operation 412, the makeup water is turned on and a fill timer is started. If the controller 52 determines 414 that the sump water has not reached the minimum level within the time period set by the fill timer, a low water level alarm is sent 416 and the controller 52 waits for the makeup assembly to be repaired. If the controller 52 determines 414 that the water level is high enough by closing the makeup float valve assembly 34, the mist pump 19 is turned on and a mist pump start timer 318 is started.

[0095] After the mist pump time period ends, the controller 52 determines 320 whether the water level exceeds the maximum water level by the sump float sensor 47 and determines 324 whether the mist pump 19 is on by, for example, the mist pump switch. If the water level is too high or the mist pump 19 is not working, the controller 52 sends 322, 326 the corresponding alarms. In the fail-safe operating mode, the wet evaporative operation of the cooling tower 20 can not be allowed until any alarms are cleared and the related components are repaired, according to manual input 500.

[0096] If the controller 52 determines 324 that the spray pump 19 is on, the controller 52 turns on the UV pump 330 and starts a UV timer to measure the UV time period, such as 10 seconds. Once the UV time period is over, the controller 52 determines 330 if the UV pump 41 is running, such as by a UV flow switch. If the UV flow switch does not detect water flowing from the UV pump 41, the controller 52 sends 432 a UV pump alarm and the UV light 42A is turned off to prevent the loop from overheating due to lack of flow. Various methods can be used to detect that the spray pump 19 and UV pump 41 are pumping, such as flow switches, differential pressure switches, and / or current sensors. Once the sump float sensor 47 determines that there is water in the sump 39, the UV pump can run continuously until the sump float sensor 47 detects that there is no water in the sump 39. This allows for continuous monitoring of some or all of the water quality parameters. If the UV pump flow switch 41C detects water flow in the side stream water loop, the controller 52 checks the intensity sensor 43 of the UV light 42. If the loss of intensity of the UV light 42 exceeds a minimum effective value, which means that the UV light 42 needs cleaning or is not working, the controller 52 sends 436 a UV light alarm.

[0097] In the fail-safe operating mode, the controller 52 in one embodiment performs an operation 438 in which the controller 52 ignores data from the conductivity, biofilm, and / or pH sensors, as in the fail-safe operating mode 400 the controller 52 has requested a service call by sending an alarm and the fail-safe operating mode 400 purges and flushes water much more frequently than the normal operating mode 300. In FIG. 4, the fail-safe operating mode is shown as not considering data from these sensors, but the ability of the controller 52 to not consider data from the conductivity, biofilm, and pH sensors is manually entered by the user.

[0098] Next the controller 52 receives feedback from the float sensor 40 and determines 440 if the float sensor 40 is running. If the feedback is that the float sensor has failed or is not working, the controller 52 sends 442 a float sensor alarm and can adjust the fan speed at operation 442, such as by limiting the speed of the fan 25 to 50% of the maximum fan speed.

[0099] If the drift sensor 40 is running, the controller 52 determines 444 whether the measured drift is above a threshold. The drift sensor 40 detects whether an unsafe amount of drift exists to reduce the risk of microbial contamination of the surrounding environment, which includes water droplets or water vapor exiting the cooling tower 20. If the drift is determined 444 to be above an acceptable parameter and depending on the biological activity parameter sensed by the biological activity sensor, the controller 52 sends 446 a drift sensor alarm and can adjust the fan speed at operation 446. The controller 52 can adjust the fan speed to a level where drift is known to be within tolerance, or the controller can shut off the fan or operate in a dry mode according to customer manual input and the controller 52.

[0100] After completing the safety checks on the sump water system and the cooling tower operation of operations 408, 414, 420, 424, 430, 434, 440, and 444, the controller 52 determines 448 whether the cooling tower 20 has been running longer than a wet timer set point, which can be set to four wet hours of operation as an example in the fail-safe operation mode 400. If the unit has been running for a time that exceeds the wet timer set point, the controller 52 will initiate 450 a purge and flush cycle 460. After the purge and flush cycle 460, the controller 520 also determines 448 whether the dry run timer has exceeded a dry run timer set point and the controller 520 will initiate 454 a dry cycle 456 when the dry run timer has exceeded the dry run timer set point. The dry cycle 456 includes an operation 457 to purge the sump of water and run the fan so that the sump 39 dries for a specified amount of time, further attempting to suppress microbial contamination. Once the dry cycle 456 is complete, the fail-safe operation mode 400 loops back to the beginning of the process. The number of dry cycles allowed can be a manual input provided by the user.

[0101] As with the purge and flush cycle 384, the controller 52 can determine 462 whether to instruct the chemical treatment system 99 to add chemicals at operation 396 instead of performing the purge and flush operation 388 when starting the purge and flush cycle 460. The operation 462 can include the controller 52 making a decision based on the current unacceptable water parameters and manual input. For example, if the pH of the water is outside of a first tolerance (resulting in the initiation of the fail-safe operation mode 400) but still within a second tolerance, the controller 52 can determine 462 to add water treatment chemicals at operation 466 instead of performing the purge and flush operation 464 of operation 464.

[0102] While the normal operating mode 300 and the failure protection operating mode 400 are discussed above as specific sequences of operations, it should be understood that the order of operations can be changed, operations can be combined or separated, and various operations can be added or omitted as needed for a particular application. As one example of this, the control logic of the modes 300, 400 can utilize two or more related evaporative liquid parameters to make a given determination. For example, the normal operating mode 300 can have an operation in which if the pH is greater than 10 and the total dissolved solids is outside of a predetermined range, the controller 52 initiates the failure protection operating mode 400. The same operation in the normal operating mode 300 can further specify that if the pH is less than 10 and the total dissolved solids is outside of a predetermined range, the controller 52 remains in the normal operating mode for a set period of time to wait and see if normal operation of the cooling tower can remedy the out-of-range total dissolved solids parameter.

[0103] As noted above, in some embodiments, the controller 52 can utilize various manual inputs as part of the control logic implemented in the normal operating mode 300 and the failure protection operating mode 400. Figure 5A and Figure 5B An example manual input 500 is provided that can be used as part of the control logic. The manual input 500 can include, for example:

[0104] Is there a sump heater?

[0105] What is the minimum ambient temperature for wet operation?

[0106] Is the cooling tower operable in dry mode?

[0107] Is the system operated in dry mode below freezing ambient temperatures?

[0108] What is the minimum allowable spray temperature for wet operation?

[0109] Is there a UV system installed on the makeup water?

[0110] Is there a UV system installed in the tower?

[0111] Is there a UV system installed in the side stream?

[0112] Is the water supply shut off when there is a high water level alarm?

[0113] In the failure protection mode, is there a tendency to more frequently purge and flush regardless of water quality sensors?

[0114] Is the water quality monitored off-site and is this information input into the controller?

[0115] Is the water treatment system controlled by the controller?

[0116] Does the controller need to operate the blowdown when the conductivity is too high?

[0117] What is the conductivity value for the water treatment system?

[0118] What is the conductivity value for the controller to take over the blowdown control?

[0119] What is the minimum effective UV lamp intensity?

[0120] What is the minimum acceptable level of bioactivity or biofilm and the difference?

[0121] Is it preferable to continue running the unit or to shut down in the event of an abnormal condition?

[0122] Is the cooling tower equipped with a backup biocide?

[0123] Is it more preferable to add chemicals than to purge and flush cycles during abnormal bioactivity conditions?

[0124] What is the number of purge and flush cycles before activating the fail-safe mode?

[0125] What is the appropriate pH value and the difference?

[0126] Is the cooling tower equipped with pH control chemicals?

[0127] What is the pH level of the makeup water?

[0128] Is it more preferable to add chemicals than to purge and flush cycles during abnormal pH conditions?

[0129] What is the maximum acceptable limit of drift?

[0130] Is it preferable to reduce the fan speed or to shut down the tower during unacceptable drift conditions?

[0131] What is the maximum acceptable rate of plume?

[0132] Is it preferable to operate the plume elimination system, reduce the fan speed, or shut down the tower during unacceptable plume conditions?

[0133] What is the number of flush cycles during normal operating mode?

[0134] What is the number of flush cycles during fail-safe operating mode?

[0135] Is the unit equipped with a high-speed pump to assist in the flushing operation?

[0136] Is a dry cycle required and at what frequency?

[0137] Draining the sump when there is no demand for cooling?

[0138] Unless otherwise stated herein or clearly contradicted by context, the use of singular terms will be taken to include the plural. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms. The phrase "at least one of" is intended to be interpreted in the disjunctive sense. For example, the phrase "at least one of A and B" is intended to encompass A, B, or A and B.

[0139] While particular embodiments of the present application have been illustrated and described, it would be understood by those skilled in the art that various changes and modifications can be made and equivalents can be substituted for elements without departing from the scope of the present application. For example, while the control logic of the normal and fail-safe operating modes 300, 400 is described with reference to the cooling tower 20, it should be understood that some or all of the normal and fail-safe operating modes 300, 400 can be implemented by the control system of the cooling tower 10.

Claims

1. A cooling tower, comprising: An evaporative heat exchanger configured to receive process fluid; A fan assembly operable to generate airflow relative to the evaporative heat exchanger; An evaporative liquid distribution system includes at least one outlet for distributing evaporative liquid to an evaporative heat exchanger and a collection tank for collecting the evaporative liquid from the evaporative heat exchanger. Evaporated liquid distribution system; Evaporated liquid handling system; An evaporating liquid sensor for an evaporating liquid distribution system is configured to detect evaporating liquid parameters; A controller, operably coupled to the fan assembly and the evaporative liquid distribution system, is configured to: The evaporating liquid handling system is operated when the evaporating liquid quality is determined to be insufficient, at least in part based on evaporating liquid parameters; and When it is determined that the evaporative liquid treatment system cannot remedy the insufficient quality of the evaporative liquid, the operation of the evaporative liquid distribution system is modified to ensure the safe operation of the cooling tower.

2. The cooling tower according to claim 1, characterized in that, The controller is configured to operate the cooling tower in wet and dry modes. In wet mode, the controller causes the evaporative liquid distribution system to distribute evaporative liquid to the evaporative heat exchanger; in dry mode, the controller restricts the evaporative liquid distribution system from distributing evaporative liquid to the evaporative heat exchanger. The controller is configured to alter the operation of the evaporative liquid distribution system, including avoiding operation of the cooling tower in wet mode when it is determined that the evaporative liquid handling system cannot remedy insufficient evaporative liquid quality.

3. The cooling tower according to claim 1, characterized in that, The controller is configured to operate the cooling tower in dry mode, wet mode, and adiabatic mode; and The controller is configured to alter the operation of the evaporative liquid distribution system when it is determined that the evaporative liquid handling system cannot remedy insufficient evaporative liquid quality, including the controller avoiding operation of the cooling tower in the wet mode and the adiabatic mode.

4. The cooling tower according to claim 1, characterized in that, The evaporative liquid handling system is operable to remove evaporative liquid and provide fresh evaporative liquid; and The controller is configured to operate the evaporating liquid treatment system when it is determined that the quality of the evaporating liquid is insufficient, including removing the evaporating liquid and providing new evaporating liquid.

5. The cooling tower according to claim 1, characterized in that, The controller is configured to periodically purge the evaporated liquid from the evaporating liquid handling system and provide fresh evaporating liquid; and The controller is configured to alter the operation of the evaporating liquid distribution system, including increasing the frequency at which the evaporating liquid distribution system removes evaporating liquid and provides new evaporating liquid.

6. The cooling tower according to claim 1, characterized in that, The controller is configured to operate the evaporative liquid treatment system, including at least one of the following: opening the make-up liquid supply valve, opening the drain valve, running the purge and flushing cycle, and adding treatment chemicals to the evaporative liquid; and The controller is configured to alter the operation of the evaporating liquid distribution system, including at least one of the following: shutting off the spray pump, adjusting the operation of the fan assembly, running a cleaning and flushing cycle, and adding treatment chemicals to the evaporating liquid.

7. The cooling tower according to claim 1, characterized in that, The sensor includes at least one of a conductivity sensor, a biofilm sensor, and a pH sensor; The parameters include at least one of conductivity, biofilm, and pH. The controller is configured to disregard at least one of the conductivity parameter, biofilm parameter, and pH parameter after the controller changes the operation of the evaporative liquid distribution system.

8. The cooling tower according to claim 1, characterized in that, The determination that the evaporative liquid treatment system cannot resolve the insufficient quality of the evaporative liquid is based at least in part on the predetermined number of times the controller operates the evaporative liquid treatment system within a predetermined time period.

9. The cooling tower according to claim 1, characterized in that, The evaporative liquid treatment system is unable to resolve insufficient evaporative liquid quality, at least in part, because the parameters of the evaporative liquid exceed the threshold for a predetermined period of time.

10. The cooling tower according to claim 1, characterized in that, After the controller operates the evaporative liquid handling system, the sensors can be used to detect evaporative liquid parameters; and The determination that the evaporating liquid treatment system cannot solve the problem of insufficient evaporating liquid quality is based at least in part on the evaporating liquid parameters after the controller operates the evaporating liquid treatment system.

11. The cooling tower according to claim 1, characterized in that, The controller is configured to detect a fault in at least one component of the evaporative liquid distribution system; and The inability of the evaporative liquid distribution system to resolve insufficient liquid quality is determined to be at least in part due to a failure of at least one component of the evaporative liquid distribution system.

12. The cooling tower according to claim 1, characterized in that, The evaporative liquid distribution system includes a spray pump; and The controller is configured to alter the operation of the evaporative liquid distribution system, including keeping the spray pump off.

13. The cooling tower according to claim 1, characterized in that, The controller includes communication circuitry; The controller is configured to send a notification to a remote computing device via a communication circuit when it is determined that the evaporating liquid treatment system cannot remedy the insufficient evaporating liquid quality; and The controller maintains the change to the evaporating liquid distribution system until it receives a response to the notification.

14. The cooling tower according to claim 1, characterized in that, Evaporated liquid handling system: includes: Circular loop; A pump operable to guide the evaporated liquid through the circulation loop; and An ultraviolet lamp treatment system is configured to treat the evaporating liquid in a circulating system.

15. The cooling tower according to claim 1, characterized in that, The evaporative liquid handling system includes: Replenish fluid supply; and The ultraviolet lamp treatment system is configured to treat the supplemental liquid supplied by the supplemental liquid supply.

16. The cooling tower according to claim 1, characterized in that, The evaporating liquid treatment system includes a chemical treatment system configured to add chemical treatment to the evaporating liquid.

17. The cooling tower according to claim 1, characterized in that, The parameters of the evaporated liquid include at least one of the following: temperature; Electrical conductivity; Bioactive materials; Biomembranes; pH level; Feather Stream; and Floating objects.

18. The cooling tower of claim 1, further comprising at least one operating parameter sensor configured to detect operating parameters, said operating parameters including at least one of the following: Ambient temperature; Water level in the collection tank; Spray pump operation; Water collection tank cleaner pump; Side-flow UV pump operation; The intensity of the UV lamps in the water supply path; and The determination of insufficient evaporated liquid quality is based at least in part on the evaporated liquid parameters and operating parameters.

19. The cooling tower of claim 1, further comprising a collector for collecting at least a portion of the evaporated liquid from the evaporative heat exchanger and directing the evaporated liquid to a collection tank; and The fan assembly is located below the collector.

20. The cooling tower according to claim 1, further comprising an external structure; The indirect heat exchanger is located in the external structure; The external structure occupies space; and The water collection tank occupies less than half the space of the external structure.

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