阅读说明：本技术 智能海水冷却系统
(Intelligent seawater cooling system
) 是由 尹丹
S·沃纳
C·马丁
M·霍夫曼
D·麦金斯特里 于 2015-07-13 设计创作，主要内容包括：一种海水冷却系统,其包括：联接至换热器的第一侧和热负荷的第一流体冷却回路；第二流体冷却回路,其联接至换热器的第二侧且包括用于循环通过第二流体冷却回路的流体的泵；和操作性地连接至泵的控制器,其中,所述控制器配置成监测第一流体冷却回路中的实际温度且基于被监测的温度调节泵的速度以实现第一流体冷却回路中的预定温度。所述系统能够选择性地在多个操作模式依据中操作,其中,在第一操作模式中,泵完全基于热负荷的冷却需求操作,且在第二操作模式中,泵操作以维持高于预定压力的流体压力。(A seawater cooling system, comprising: a first fluid cooling circuit coupled to a first side of the heat exchanger and a thermal load; a second fluid cooling circuit coupled to a second side of the heat exchanger and including a pump for circulating fluid through the second fluid cooling circuit; and a controller operatively connected to the pump, wherein the controller is configured to monitor an actual temperature in the first fluid cooling circuit and adjust a speed of the pump based on the monitored temperature to achieve a predetermined temperature in the first fluid cooling circuit. The system is selectively operable in a plurality of operating modes, wherein in a first operating mode the pump operates entirely based on the cooling demand of the thermal load, and in a second operating mode the pump operates to maintain a fluid pressure above a predetermined pressure.)
1. A method for establishing operating parameters in a variable flowrate cooling system, comprising:
defining a pump parameter at a first controller in the system;
defining a system parameter at a first controller; and is
Automatically copying pump parameters and system parameters from a first controller to at least one other controller in the system.
2. The method of claim 1, wherein defining pump parameters comprises: the operator manually enters the pump parameters.
3. The method of claim 1, wherein pump parameters for a plurality of different pumps are stored in the first controller, and wherein defining the pump parameters comprises:
the operator specifying the type of pump connected to the first controller; and is
The first controller automatically loads pump parameters corresponding to the specified type of pump.
4. The method of claim 1, wherein pump parameters for a plurality of different pumps are stored in the first controller, and wherein defining the pump parameters comprises:
the first controller automatically identifying the type of pump connected to the first controller; and is
The first controller automatically loads pump parameters corresponding to the identified type of pump.
5. A method for establishing pump parameters in a controller of a variable flowrate cooling system, comprising:
storing in a controller pump parameters for a plurality of different types of pumps;
connecting the pump to a controller;
the controller automatically identifying a pump connected to the controller; and is
The controller automatically loads pump parameters corresponding to the identified pump.
6. A method for equalizing pump usage in a variable flowrate cooling system having a plurality of pumps, comprising:
monitoring a total operating time for each pump; and is
The use of the pumps is redistributed so that pumps with relatively low total operating time will be used more than pumps with relatively high total operating time.
7. The method of claim 6, wherein the re-dispensing of the pump comprises: the current primary pump is reallocated to backup pump operation and the current backup pump is reallocated to primary pump operation.
Technical Field
The present application relates generally to the field of seawater cooling systems, and more particularly to a system and method for controlling temperature in a fresh water cooling circuit by adjusting pump speed in a seawater cooling circuit thermally coupled to the fresh water cooling circuit.
Background
Large marine vessels are typically powered by large internal combustion engines that require constant cooling under various operating conditions, such as during high speed cruising, low speed operation near ports, and full speed operation to avoid inclement weather. Existing systems for achieving such cooling typically include one or more pumps that draw seawater into the onboard heat exchangers. The heat exchanger is used to cool a closed fresh water cooling circuit that flows through and cools the engine(s) of the ship and/or other various loads on the ship (e.g., air conditioning systems).
One drawback associated with existing seawater cooling systems, such as those described above, is that they are generally inefficient. In particular, the pumps used to draw seawater into such systems typically operate at a constant speed, regardless of the amount of seawater required to achieve adequate cooling of the associated engine. Thus, if the engine does not require a large amount of cooling, such as when the engine is idling or running at low speeds, or if the seawater drawn into the cooling system is very cold, the pump of the cooling system may provide more water than is necessary to achieve adequate cooling. In this case, the cooling system will be configured to divert some of the fresh water in the fresh water circuit directly to the discharge side of the heat exchanger where it mixes with the remaining fresh water flowing through and cooled by the heat exchanger. Thereby achieving the desired temperature in the fresh water circuit. However, such systems do not often require a sea water pump driven at a constant speed to provide the full cooling power (and therefore require water to be diverted into a fresh water circuit). Therefore, a part of the energy consumed to drive the pump is wasted. Therefore, there is a need for a more efficient seawater pump system for use in serving heat exchange systems for the marine industry.
Disclosure of Invention
In view of the foregoing, it would be advantageous to provide an intelligent seawater cooling system and method that provides improved efficiency and fuel savings over existing seawater cooling systems and methods.
An exemplary intelligent seawater cooling system according to the present application may include: a first fluid cooling circuit coupled to a first side of the heat exchanger and a thermal load; a second fluid cooling circuit coupled to a second side of the heat exchanger and including a pump for circulating fluid through the second fluid cooling circuit; and a controller operatively connected to the pump, wherein the controller is configured to monitor an actual temperature in the first fluid cooling circuit and adjust a speed of the pump based on the monitored temperature to achieve a predetermined temperature in the first fluid cooling circuit. The system is thereby selectively operable in one of a plurality of operating modes, wherein in a first operating mode the pump operates entirely based on the cooling demand of the thermal load, and in a second operating mode the pump operates to maintain a fluid pressure above a predetermined pressure.
A method for establishing operating parameters in a variable flowrate cooling system according to the present invention may comprise: pump parameters are defined at a first controller in the system, system parameters are defined at the first controller, and the pump parameters and the system parameters are automatically copied from the first controller to at least one other controller in the system.
A method for establishing pump parameters in a controller for a variable flow cooling system according to the present invention may comprise: storing pump parameters for a plurality of different types of pumps in a controller, connecting the pumps to the controller, the controller automatically identifying the pumps connected to the controller, and the controller automatically loading pump parameters corresponding to the identified pumps.
A method for equalizing pump usage in a variable flow cooling system having a plurality of pumps according to the present invention may include: the total operating time for each pump is monitored and the use of the pumps is redistributed so that pumps with relatively lower total operating times will be used more than pumps with relatively higher total operating times.
Drawings
Specific embodiments of the disclosed apparatus will now be described, by way of example, with reference to the accompanying drawings, in which:
fig. 1 is a schematic diagram illustrating an exemplary intelligent seawater cooling system according to the system.
Fig. 2 is a flow chart illustrating an exemplary method for operating the intelligent seawater cooling system illustrated in fig. 1 in accordance with the present application.
Fig. 3 is a flow chart illustrating an exemplary method for establishing parameters in the intelligent seawater cooling system illustrated in fig. 1 in accordance with the present application.
Fig. 4 is a flow chart illustrating an exemplary method for equalization pump usage in the intelligent seawater cooling system illustrated in fig. 1 in accordance with the present application.
Fig. 5 is a graph illustrating energy saving due to a reduction in pump speed.
Fig. 6 is a graph illustrating an exemplary means for determining whether to operate the system of the present application with 1 pump or 2 pumps.
Detailed Description
The intelligent seawater cooling system and method according to the present application will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the system and method are shown. The disclosed systems and methods may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbering represents like elements throughout.
Referring to FIG. 1, a schematic diagram of an exemplary intelligent seawater cooling system 10 (hereinafter "system 10") is shown. The system 10 may be mounted on any type of marine vessel or offshore platform having one or more engines 11 that require cooling. Although only a single engine 11 is shown in FIG. 1, it should be understood by those of ordinary skill in the art that engine 11 may represent multiple engines or various other loads on a vessel or platform that may be coupled to cooling system 10.
The system 10 may include a seawater cooling loop 12 and a fresh water cooling loop 14, the seawater cooling loop 12 and the fresh water cooling loop 14 being interconnected by a heat exchanger 15, as described further below. Although only a single heat exchanger 15 is shown in fig. 1, it is contemplated that the system 10 may alternatively include two or more heat exchangers for providing greater heat transfer between the seawater cooling loop 12 and the fresh water cooling loop 14 without departing from the present application.
The seawater cooling loop 12 of the system 10 may include a primary pump 16, a secondary pump 18, and a backup pump 20. The pumps 16-20 may be driven by respective variable frequency drives 22, 24, and 26 (hereinafter " VFDs 22, 24, and 26"). While the pumps 16-20 may be centrifugal pumps, it is contemplated that the system 10 may alternatively or additionally include various other types of pumps including, but not limited to, gear pumps, progressive cavity pumps, or multi-axis screw pumps, or other positive displacement or other non-positive displacement pumps.
The VFDs 22-26 may be operatively connected to the respective primary, secondary and backup pumps 28, 30, 32 via communication lines 40, 42, and 44. Various sensors and monitoring devices 35, 37, and 39 may be operatively mounted on the pumps 16, 18, and 20 and connected to the respective controllers 28, 30, and 32 via communication lines 34, 36, and 38, the sensors and monitoring devices 35, 37, and 39 including, but not limited to, vibration sensors, pressure sensors, bearing temperature sensors, leak sensors, and possibly other sensors. These sensors may be provided to monitor the health of pumps 16, 18, and 20, as described further below.
The controllers 28-32 may further be interconnected by a communication line 46. The communication line 46 may be transparent to other networks to provide supervisory communication capabilities. The controllers 28-32 may be configured to control the operation of the VFDs 22-26 (and thus the pumps 16-20) to regulate the flow of seawater to the heat exchanger 15, as described further below. The controllers 28-32 may be any suitable type of controller including, but not limited to, proportional-integral-derivative controllers (PIDs) and/or Programmable Logic Controllers (PLCs). The controllers 28-32 may include respective memory units and processors (not shown) that may be configured to receive and store data provided by the various sensors in the cooling system 10, to communicate data between the controllers and a network external to the system 10, and to store and execute software instructions for performing the method steps of the present application as described below.
The operator may establish a plurality of pump parameters at the controller 28, the VFD22, or other user interface. These pump parameters may include, but are not limited to, a reference speed, a reference efficiency, a reference flow, a reference head, a reference pressure, a speed limit, a suction pressure limit, a discharge pressure limit, a bearing temperature limit, and a vibration limit. These parameters may be provided by the pump manufacturer (such as in a reference manual) and may be input into the controller 28, the VFD22, or other user interface by an operator or external monitoring device via the communication line 46. Alternatively, it is contemplated that the controller 28, VFD22, or other user interface may be preprogrammed with pump parameters for a variety of different types of commercially available pumps, and the operator may simply specify the type of pump currently being used by the system 10 to load the corresponding set of parameters. It is also contemplated that the controller 28 or the VFD22 may be configured to automatically determine the type of pump connected in the system 10 and load the corresponding set of parameters without any operator input.
The operator may also establish a number of system parameters at the controller 28, the VFD22, or other user interface. These parameters may include, but are not limited to, fresh water temperature range, VFD motor speed range, minimum pressure level, fresh water flow, hydrothermal capacity coefficient, heat exchanger surface area, heat transfer coefficient, presence of 3-way valve, and ambient temperature limit.
The pump parameters and system parameters established at the controller 28 or the VFD22 may be copied to the other controllers 30 and 32 and/or the other VFDs 24 and 26, such as via transmission of corresponding data over the communication line 46. This copying of parameters may be performed automatically or upon entry of appropriate commands by an operator at the controller 28, VFD22, or other user interface. Thus, the operator need only enter parameters once at a single interface, rather than having to enter parameters at each of the controllers 28-32 and/or VFDs 22-26 as in other pump systems.
The communication lines 34-46 and the communication lines 81, 104 and 108 described below are illustrated as hard-wired connections. However, it should be understood that the communication lines 34-46, 91, 104 and 108 of the system 10 may be embodied by various wireless or hardwired connections. For example, the communication lines 34-46, 91, 104, and 108 may use Wi-Fi, Bluetooth, the Public Switched Telephone Network (PSTN), a satellite network system, a cellular network (e.g., Global System for Mobile communications (GSM) for SMS and packet voice communications), General Packet Radio Service (GPRS) for encapsulating data and voice communications, or a wired data network (e.g., Ethernet/Internet for TCP/IP, VOIP communications), among others.
The seawater cooling loop 12 may include various piping and piping system components ("pipes") 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70 for drawing water from the ocean 72 by pumps 16-20 and circulating the seawater through the seawater cooling loop 12 on the seawater side including the heat exchanger 15, as further described below. The pipes 50-70, as well as the pipes 84, 86, 88, 90, 92, 94, 95, 97, 99, and 101 of the fresh water cooling circuit 14 and the additional systems 103, 105, and 107 described below, may be any type of rigid or flexible conduit, pipe, tube, or pipe suitable for transporting seawater, and may be disposed on a vessel or platform in any configuration as appropriate for a particular application.
The seawater cooling loop 12 may further include a discharge valve 89 disposed intermediate the conduits 68 and 70 and connected to the main controller 28 via a communication line 91. It is conceivable that the discharge valves 89 can also be connected to the secondary controller 30 and/or the backup controller 32, since these controllers can automatically recognize the connected discharge valves 89 and can automatically distribute information about the connection of the discharge valves 89 to one another via the communication line 46. The bleed valve 89 may be adjustably opened and closed to vary the operating characteristics (e.g., pressure) of the pumps 16-20, as further described below. In one non-limiting exemplary embodiment, the exhaust valve 89 is a throttle valve.
The fresh water cooling circuit 14 of the system 10 may be a closed fluid circuit including a fluid pump 80 and various conduits and components 84, 86, 88, 90, 92, and 94 for continuously pumping and transporting fresh water through the heat exchanger 15 and the engine 11 to cool the engine 11, as further described below. The fresh water cooling circuit 14 may also include a three-way valve 102, the three-way valve 102 being connected to the main controller 28 via a communication line 104 to controllably bypass a prescribed amount of water in the fresh water cooling circuit 14 from the heat exchanger 15, as described further below.
The temperature in the fresh water cooling loop 14 may be measured and monitored by the main controller 28 to facilitate various control operations of the cooling system 10. Such temperature measurement may be performed by a resistance temperature detector 106 (hereinafter "RTD 106") or other temperature measurement device operatively connected to the fresh water cooling circuit 14. Although RTD106 is illustrated in fig. 1 as measuring the temperature of fresh water cooling circuit 14 on the inlet side of engine 11, it is contemplated that RTD106 may alternatively or additionally measure the temperature of fresh water cooling circuit 14 on the outlet side of engine 11. RTD106 may be connected to host controller 28 via communication line 108, or alternatively RTD106 may be an integrated onboard component of host controller 28. It is contemplated that RTD106 may also be connected to secondary controller 30 and/or backup controller 32 because these controllers may automatically identify connected RTD106 and may automatically distribute information regarding the connection of RTD106 to each other via communication lines 46.
The seawater cooling loop 12 may additionally provide seawater to various other systems of the vessel or platform for assisting in the operation of such systems. For example, seawater from the seawater cooling loop 12 may be provided to one or more of the fire suppression system 103, the ballast control system 105, and/or the seawater diversion system 107 on an as-needed basis. Although not shown, other seawater-operated systems that may receive seawater from the seawater cooling loop 12 in a similar manner include, but are not limited to, sewage blowdown, deck cleaning, air conditioning, and fresh water generation.
In the exemplary system 10 illustrated in fig. 1, seawater may be provided to the system 103 and 107 via conduits 95, 97, 99, and 101, which may be connected to the seawater cooling loop 12 at, for example, conduit 66. The conduits 95-101 may be provided with various manual or automatic control valves (not shown) for introducing the flow of seawater into the system 103 and 107 in a desired manner. Of course, it will be appreciated that if seawater is supplied to the system 103-107, the flow of seawater through the heat exchanger 15 will be reduced, which may cause the temperature in the fresh water cooling loop 14 to rise unless the operation of the pumps 16-20 is modified. Thus, the pumps 16-20 may be controlled in a manner that compensates for the seawater used by the system 103 and 107, as will be described in greater detail below.
It is contemplated that system 10 may monitor the total amount of time each of pumps 16-20 has been operating and may redistribute the operation of pumps 16-20 in a manner that equalizes or attempts to equalize the operating time of pumps 16-20. For example, if the primary pump 16 has recorded 100 hours of operation, the secondary pump 18 has recorded 50 hours of operation, and the backup pump has recorded only 5 hours of operation, the system 10 may reallocate the primary pump 16 for backup pump operation and may reallocate the backup pump 20 for primary pump operation. Thus, pumps 18 and 20 may continue to accumulate active operating time while pump 16 maintains a substantially idle speed. Thus, by equalizing the operating times of the pumps 16-20, the pumps 16-20 may be caused to wear at a substantially uniform rate and may therefore be maintained or replaced according to a uniform schedule.
The equalization procedure described above may be performed automatically, such as according to a predetermined schedule. For example, when one of the pumps 16-20 accumulates a predetermined (e.g., operator defined) amount of operating time since the last reassignment, an equalization procedure may be performed and the role of the pump 16-20 may be reassigned as needed for equalized use. The equalization program may also be manually turned on at the operator's discretion, such as by entering an appropriate command at an operator interface.
The system 10 may be operated in a number of different operator selectable modes, such as modes that may be selected via an operator interface (not shown), where each operating mode may be indicative of a particular minimum system pressure to be maintained by the system 10. For example, the first mode of operation may be a "no threshold" or similar designated mode that, if selected, would cause the system 10 to operate the pumps 16-20 without regard to any predetermined or specified minimum system pressure. In other words, the system 10 will operate the pumps 16-20 based solely on the cooling needs of the engine 11. For example, if any seawater operating system (e.g., ballast control system 105) draws seawater from seawater cooling loop 12, the flow of seawater through heat exchanger 15 will be reduced, thereby reducing the amount of cooling in fresh water cooling loop 14. Thus, the temperature of the water in the fresh water cooling circuit 14 may increase. As described above, the primary controller 28 may then determine that the monitored fresh water temperature exceeds or is about to exceed the predetermined temperature level, and the primary controller 28 may respond by increasing the speed of the VFD22, and may issue commands to the secondary controller 30 to increase the speed of the VFD 24. Thus, the corresponding primary pump 16 and/or secondary pump 18 are driven faster and the flow of seawater through the seawater cooling circuit 12 is increased. Thereby providing greater cooling at the heat exchanger 15 and the temperature in the fresh water cooling circuit 14 is therefore reduced. Thus, by driving the pumps 16-20 only as needed to meet contemporaneous demand, a sufficient amount of seawater can be supplied for cooling the engine 11 and for operating the marine operating system of the vessel in a pure "on-demand" fashion, thereby optimizing the efficiency of the system 10. This is to be contrasted with conventional seawater cooling systems that maintain a minimum system pressure (i.e., a minimum seawater pressure that has been determined to be required for operating some or all of the seawater operating systems of the ship) constant regardless of contemporaneous system demand.
The second selectable operating mode may be a "minimum threshold" or similar designated mode that, if selected, may allow the operator to manually enter the minimum threshold and thereafter cause the system 10 to operate the pumps 16-20 in a manner that maintains the system pressure of the vessel above the manually specified threshold. The minimum threshold may be a value below the minimum system pressure (described above), but this provides some constant maintenance amount of seawater pressure in the vessel's system. The system pressure of the vessel may be monitored by sensors integral with the vessel and independent of the system 10, and may be communicated to the system 10 via a communication line, such as communication line 46. The "minimum threshold" mode may be applicable to the following cases: the system operator is not accustomed to operating the system 10 in a purely on-demand manner (as in the "no threshold" mode described above) but still wants to achieve a higher level of system efficiency compared to conventional seawater cooling systems that constantly maintain a minimum system pressure. After the system operator becomes accustomed to the on-demand performance of the system 10, the operator may lower or completely remove the minimum threshold. This flexibility provides the system operator with the option of meeting the needs of their application.
A third optional mode of operation may be a "minimum system pressure" or similar designated mode that, if selected, will cause the system 10 to operate the pumps 16-20 in a manner that maintains the system pressure of the vessel above a predetermined (e.g., pre-calculated) minimum system pressure for the vessel. As described above, the minimum system pressure may be the minimum seawater pressure that has been determined to be required for operating some or all of the seawater operating systems of the vessel. Likewise, the system pressure of the vessel may be monitored by sensors integral with the vessel and independent of the system 10, and may be communicated to the system 10 via a communication line. The "minimum system pressure" mode may be applicable to the following cases: the system operator is not accustomed to operating the system 10 in a purely on-demand manner (the "no threshold" mode described above) or to maintaining a system pressure that is less than the minimum system pressure (the "minimum threshold" mode described above).
It will be appreciated that the above-described modes of operation provide flexibility to the system 10 to adapt to various system operator preferences without having to reconfigure system components prior to installation. Additionally, if the operator's preferences change over time, such as if the operator begins to hesitate to operate the system 10 at a pressure less than the minimum system pressure, the operator may seamlessly switch between operating modes and gradually transition to pure on-demand operation as his/her level of habit increases.
Referring to FIG. 2, a flowchart of a general exemplary method for operating the system 10 according to the present application is shown. The method will be described in connection with the schematic diagram of the system 10 shown in fig. 1. Unless otherwise indicated, the described methods may be performed in whole or in part by the controllers 28-32, such as by executing various software algorithms with their processors.
In step 200, the system 10 may be started, such as by an operator making an appropriate selection in an operator interface (not shown) of the system 10. When activated, the operator may be prompted to select an operating mode that may indicate a minimum system pressure to be maintained by the system 10. For example, the operator may be prompted to select one of the "no threshold," "minimum threshold," or "minimum system pressure" operating modes described above.
Once the system 10 has been started and the operating mode has been designated, the primary and secondary controllers 28 and 30 may command the VFDs 22 and 24 to begin driving the at least one pump 16 and 18 in step 210 of the exemplary method. Thus, pumps 16 and 18 may begin to draw seawater from ocean 72, pass it through conduits 52 and 54, pumps 16 and 18, conduits 58-66, heat exchanger 15, and finally return to ocean 72 through conduits 68 and 70. As the seawater flows through the heat exchanger 15, it may cool the fresh water in the fresh water cooling circuit 14 that also flows through the heat exchanger 15. The cooled fresh water then flows through the engine 11 and cools the engine 11.
In step 220 of the exemplary method, main controller 28 may monitor the temperature of the fresh water in fresh water cooling loop 14 via RTD 106. Accordingly, the main controller 28 may determine whether the fresh water is at a temperature required to provide adequate cooling for the engine 11, such as by comparing the monitored temperature to a predetermined temperature range. For example, the desired temperature level of the fresh water at the discharge of the heat exchanger may be 35 degrees Celsius, and the temperature range may be +/-3 degrees Celsius.
If the primary controller 28 determines in step 220 that the monitored temperature of the fresh water exceeds or is about to exceed the predetermined temperature level, the primary controller 28 may increase the speed of the VFD22 and may issue a command to the secondary controller 30 to increase the speed of the VFD 24 in step 230 of the exemplary method. Thus, the corresponding primary pump 16 and/or secondary pump 18 are driven faster and the flow of seawater through the seawater cooling loop 12 is increased. Thereby, greater cooling is provided at the heat exchanger 15 and thus the temperature in the fresh water cooling circuit 14 is reduced. The main controller 28 can additionally command the three-way valve 102 to adjust its position and thereby the amount of fresh water in the fresh water cooling circuit 14 through the heat exchanger 15 to achieve optimal cooling of the fresh water.
Conversely, if the primary controller 28 determines in step 220 that the monitored fresh water temperature is below or is about to be below the predetermined temperature level, the primary controller 28 may decrease the speed of the VFD22 and may issue a command to the secondary controller 30 to, for example, decrease the speed of the VFD 24 in step 240 of the exemplary method. Thus, the respective primary and secondary pumps 16, 18 are driven more slowly, reducing the flow of seawater through the seawater cooling loop 12. Thus, less cooling is provided at the heat exchanger 15 and, therefore, the temperature in the fresh water cooling circuit 14 is increased. The main controller 28 may additionally direct the three-way valve 102 to adjust its position such that some or all of the fresh water in the fresh water cooling circuit 14 is diverted to bypass the heat exchanger 15 to further reduce the cooling of the fresh water.
Regardless of how little cooling may be required by the engine 11, if the "minimum threshold" mode or the "minimum system pressure" mode is selected in step 200 above, both pumps 16 and 18 will be driven at a speed that does not allow the system pressure of the vessel being monitored to be below the predetermined minimum system pressure or the specified minimum threshold (described above), respectively. Thus, a certain minimum level of seawater pressure may be maintained throughout the system of the vessel for supplying seawater to the seawater operating system.
If the "no threshold" mode is selected in step 200, the system 10 will not operate according to any predetermined or specified minimum system pressure, but will then operate as described above only in response to the cooling requirements of the engine 11 to ensure that a sufficient amount of seawater is pumped in an as-needed manner to provide engine cooling and to supply the seawater operating system.
In certain situations, such as if the system 10 is operating in particularly cooled water and/or if the engine 11 is idling, it may be desirable to reduce the flow of seawater in the seawater cooling loop 12 below that which can be achieved by reducing the pump speed while maintaining stable operation of the pumps 16 and 18. In other words, no matter how small a flow is required in the seawater cooling circuit 12, it may be necessary to operate the pumps 16 and 18 at a minimum safe operating speed to avoid, for example, cavitation or damage to the pumps 16 and 18. If the primary controller 28 determines that such a low flow rate of seawater is desirable, then in step 250 the primary controller 28 may reduce the speed of the VFD22 to drive the primary pump 16 at or near the minimum safe operating speed, may direct the secondary controller to reduce the speed of the VFD 24 to drive (or shut off) the secondary pump 18 at or near the minimum safe operating speed, and may further direct the partial closure of the discharge valve 89 to maintain the desired minimum system discharge pressure. Thus, by partially closing the discharge valve 89, the flow in the seawater cooling loop 12 may be limited/reduced without further reducing the operating speed of the pumps 16 and 18, and the minimum required system pressure may be maintained. Thus, the pumps 16 and 18 can be operated above the minimum safe operating speed of the pumps 16 and 18 while achieving the low flow rates required in the seawater cooling loop 12. The bleed valve 89 may be controlled in a similar manner to maintain the system pressure of the vessel above a predetermined or specified system pressure (i.e., if the "minimum system pressure" mode or the "specified pressure" mode is selected in step 200).
By continuously monitoring the temperature in the fresh water cooling circuit 14 and adjusting the pump speed and flow in the seawater cooling circuit 12 in the manner described above, the pumps 16 and 18 can be driven only as fast as is necessary to provide the amount of cooling required at the heat exchanger 15 and/or to maintain a predetermined or specified minimum system pressure. Thus, the system 10 may operate more efficiently and may provide significant fuel savings over conventional seawater cooling systems that drive a seawater pump at a constant speed despite temperature variations. This efficiency improvement is illustrated in the graph of fig. 5. It will be understood by those of ordinary skill in the art that the pump power "P" is proportional to the cube of the pump speed "n" and the flow rate "Q" is proportional to the pump speed "n". Thus, while the disclosed system 10 is low due to the lower cooling requirements from the engineRather than running the pump at maximum speed and simply dumping the excess flow split or through the recirculation loop, significant energy savings can be achieved. For example, if Q is the rated seawater flow Q opt50% of their rated speed, then pumps 16, 18 need only operate at 50% of their rated speed to provide Q opt50% of the total. This reduction in speed results in an 87.5% reduction in power "P" compared to prior art systems that operate the pumps 16, 18 at a constant maximum speed.
In step 260 of the exemplary method, the main controller 28 may determine whether the system 10 should operate in the 1-pump mode or the 2-pump mode in order to achieve the desired efficiency and more energy savings. In other words, it may be more efficient to drive only one of the pumps 16 or 18 without driving the other pump under certain circumstances (e.g., if minimal cooling is required). Alternatively, it may be more efficient and/or necessary to drive both pumps 16 and 18 at a lower speed. The master controller 28 may make this determination by comparing the operating speeds of the pumps 16 and 18 to a predetermined "switch point". "switching Point" Q/Q operated by 1-Pump or 2-PumpoptThis can result in a more efficient system. For example, if the system 10 is operating in the 2-pump mode and both pumps 16 and 18 are driven at less than a predetermined efficiency point, the main controller 28 may deactivate the secondary pump 18 and operate only the primary pump 16. Efficiency Q/Q while the 1-pump is runningoptWill increase, resulting in a more efficient system than 2-pump operation. Conversely, if the system 10 is operating in a 1-pump mode of operation (e.g., running only the primary pump 16) and the primary pump 16 is being driven at greater than a predetermined efficiency point, the primary controller 28 may activate the secondary pump 18.
As shown in FIG. 6, the switch point (between one and two pump operations) may be based on the actual flow "Q" and the optimal flow range "Q" of the system 10opt"is determined by comparison. According to an exemplary curve, Q/Q when operating with a single pumpoptAbove 127%, the system may switch to two pump operation to achieve the most efficient operation. Likewise, Q/Q when operating with two pumpsoptFalling below 74%, the system may switch to single pump operation. At the same time, the discharge valve is controlled so as to always remain as desiredMinimum system discharge pressure.
In step 270 of the exemplary method, the primary controller 28, the secondary controller 30, and the standby controller 32 may periodically transmit data packets to one another, such as via the communication line 46. These data packets may include information regarding the critical operating state or "health" of the various controllers 28-32, including the respective pumps 16-20 and VFDs 22-26. If it is determined that one of the controllers 28-32 has stopped operating properly or is tending to indicate a direction of a recent or future failure, or if its communication line has failed or is inactive, the role of that controller may be reassigned to another controller. For example, if it is determined that the sub-controller 30 has properly ceased operation, the duties of the sub-controller 30 may be reassigned to the standby controller 32. Alternatively, if it is determined that the primary controller 28 has properly ceased operation, the duties of the primary controller 28 may be reassigned to the secondary controller 30 and the duties of the secondary controller 30 may be reassigned to the backup controller 32. Thus, system 10 is provided with a level of automatic redundancy that allows system 10 to continue normal operation even after a component failure occurs. If a stopped or problematic controller is trimmed and/or restored to operational status and back in operation, then information will be broadcast over the communication line to the other controllers, and the standby controller will automatically stop operation of its pump and will be in standby mode to provide future demand for its standby role.
Referring to FIG. 3, a flow chart illustrating an exemplary method for inputting operating parameters into the system 10 in accordance with the present application is illustrated.
In a first step 300 of the exemplary method, an operator may establish a plurality of pump parameters at the controller 28, the VFD22, or other user interface. As described above, these pump parameters may include, but are not limited to, a reference speed, a reference efficiency, a reference flow, a reference head, a reference pressure, a speed limit, a suction pressure limit, a discharge pressure limit, a bearing temperature limit, and a vibration limit. These parameters may be provided by the pump manufacturer (such as in a reference manual) and may be manually entered into the controller 28, VFD22, or other user interface by an operator or by an external monitoring device via the communication line 46 in step 310 a. Alternatively, it is contemplated that the controller 28, VFD22, or other user interface may be preprogrammed with pump parameters as described above for a variety of different types of commercial pumps, and the operator may simply specify the type of pump currently being used by the system 10 in step 310b to load the corresponding set of parameters. In another contemplated embodiment, the controller 28 or the VFD22 may be configured as indicated in step 310c to automatically determine the type of pump connected in the system 10 and automatically load the corresponding set of parameters without any operator input.
In step 320 of the exemplary method, the operator may establish a plurality of system parameters at the controller 28, the VFD22, or other user interface. These parameters may include, but are not limited to, fresh water temperature ranges, VFD motor speed ranges, minimum pressure levels, fresh water flow, hydrothermal capacity coefficients, heat exchanger surface area, heat transfer coefficients, presence of three-way valves, and ambient temperature limits.
In step 330 of the exemplary method, the pump parameters and system parameters established in the previous steps may be copied to the other controllers 30 and 32 and/or other VFDs 24 and 26, such as via transmission of corresponding data over the communication line 46. This copying of parameters may be performed automatically or upon entry of an appropriate command by an operator at the controller 28, VFD22, or other user interface. Thus, the operator need only enter parameters once at a single interface, rather than having to enter parameters at each of the controllers 28-32 and/or VFDs 22-26 as in other pump systems.
Referring to FIG. 4, a flow chart illustrating an exemplary method for use of the pumps 16-20 of the equalization system 10 according to the present application is shown.
In step 400 of the exemplary method, system 10 may monitor the total amount of time each of pumps 16-20 has been operating. In step 410, the system 10 may determine whether one of the pumps 16-20 has operated for longer than a specified amount of time for at least one of the other pumps 16-20. In step 420, the system 10 may redistribute the operation of the pumps 16-20 in a manner that equalizes or attempts to equalize the operating time of the pumps 16-20. For example, if the primary pump 16 has recorded 100 hours of operation, the secondary pump 18 has recorded 50 hours of operation, and the backup pump has recorded only 5 hours of operation, the system 10 may reallocate the primary pump 16 for backup pump operation and may reallocate the backup pump 20 for primary pump operation. Thus, pumps 16 and 20 may continue to accumulate active operating time while pump 16 remains substantially idle. Thus, by equalizing the operating times of the pumps 16-20, the pumps 16-20 may be caused to wear at a substantially uniform rate and may therefore be repaired or replaced according to a uniform schedule.
The equalization procedure described above may be performed automatically, such as according to a predetermined schedule. For example, when one of the pumps 16-20 accumulates a predetermined (e.g., operator defined) amount of operating time since the last reassignment, an equalization procedure may be performed and the roles of the pumps 16-20 may be reassigned as needed for equalized use. The equalization program may also be manually initiated at the operator's discretion, such as by entering an appropriate command at an operator interface.
The term "computer" as used herein may include any processor-based or microprocessor-based system including systems using microcontrollers, Reduced Instruction Set Circuits (RISC), Application Specific Integrated Circuits (ASICs), logic circuits, and any other circuit or processor capable of executing the functions described herein. The above examples are exemplary only, and are thus not intended to limit in any way the definition and/or meaning of the term "computer".
The computer system executes a set of instructions stored in one or more memory elements in order to process input data. The storage elements may also store data or other information as desired or needed. The memory element may be in the form of an information source or a physical memory element within the processor.
The set of instructions may include various commands that direct a computer, which is a processing machine, to perform specific operations, such as the methods and processes of embodiments of the present invention. The set of instructions may be in the form of a software program. The software may be in various forms, such as system software or application software. Further, the software may be in the form of a collection of separate programs, a program module within a larger program, or a portion of a program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by a processing machine may be in response to a user command, or in response to the results of a previous processing, or in response to a request by another processing machine.
The term "software" as used herein includes any computer program stored in memory for execution by a computer, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are exemplary only, and are thus not limiting as to the types of memory usable for storage of a computer program.
