JP7533112B2 - Ballast Water Treatment System - Google Patents

Description

The present invention relates to a ballast water treatment device equipped with an ultraviolet reactor.

When tankers and other ships set sail again for their destination after unloading their cargo of crude oil, they usually store water called ballast water in ballast tanks to balance the ship while it is sailing. These ships are equipped with ballast water treatment equipment that purifies the ballast water to prevent damage to the ecosystem caused by the injection and discharge of ballast water.

One type of ballast water treatment device is equipped with an ultraviolet reactor and kills microorganisms in the ballast water by irradiating them with ultraviolet light (see, for example, Patent Document 1).

JP 2014-227063 A

However, when using such a ballast water treatment device to purify and store ballast water and then discharge it, it is necessary to comply with discharge regulations set by organizations such as the International Maritime Organization (IMO) and the United States Coast Guard (USCG). In order to make such discharge regulations effective, the ballast water treatment device must obtain type approval from a designated organization with specifications that comply with the discharge regulations. However, there are multiple approval organizations that issue type approvals for the same discharge regulations (e.g., USCG discharge regulations), and it is also possible to obtain type approval for multiple specifications (operating modes) for the same discharge regulations.

However, even if a ballast water treatment system is type-approved and can operate in multiple operating modes, it is difficult to select an appropriate operating mode depending on the situation.

The present invention was made in consideration of these circumstances, and provides a ballast water treatment device that is capable of determining the appropriate operating mode when multiple operating modes are available.

According to the present invention, there is provided a ballast water treatment device that purifies circulating ballast water, the ballast water treatment device comprising: an ultraviolet reactor capable of adjusting the amount of ultraviolet irradiation; a control means for controlling the ballast water treatment device in one operating mode selected from a plurality of operating modes; a salinity measurement means for measuring the salinity of the circulating ballast water; and an allowable discharge time acquisition means for acquiring the allowable discharge time from when the ballast water after treatment by the ultraviolet reactor is stored in a ballast tank until when it is discharged, wherein each of the plurality of operating modes has a tank retention time set for which the treated ballast water must be held in the ballast tank, and the control means determines the appropriate operating mode based on the following (1) and/or (2) as judgment criteria.
(1) the salinity measured by the salinity measurement means; (2) a comparison between the allowable discharge time acquired by the allowable discharge time acquisition means and the tank retention time;

According to the present invention, by using the above (1) and/or (2) as the criteria for determining the appropriate operating mode, it becomes possible to operate the ballast water treatment device in an appropriate operating mode depending on the water area and the allowable discharge time.

The tank retention time is a time set to prevent the ballast water taken into the ballast tank from being discharged without completely destroying the microorganisms contained in the ballast water. Some of the operating modes that have been type approved as described above have tank retention times set for each water area, and the tank retention times differ for each operating mode. Therefore, in a certain water area, the allowable discharge time is longer than the tank retention time in a certain operating mode, so there is no problem, but in other operating modes, the allowable discharge time is shorter than the tank retention time, so the ballast water cannot be discharged at the desired timing. In this regard, the control means according to the present invention can prevent such problems from occurring by comparing the allowable discharge time acquired by the allowable discharge time acquisition means with the tank retention time in addition to information about the current water area.

Various embodiments of the present invention are illustrated below. The embodiments shown below can be combined with each other.

Preferably, the control means identifies the water area using (1) as a judgment criterion, the water area including a first water area and a second water area having a higher salinity than the first water area, and the control means determines an appropriate operating mode in the first water area using (2) as a judgment criterion.

Preferably, the system includes a flow rate adjusting means for adjusting the treatment flow rate of the circulating ballast water, and a transmittance acquiring means for acquiring the ultraviolet transmittance of the circulating ballast water, and the treatment flow rate and the ultraviolet irradiation amount of the ballast water are determined for each of the plurality of operation modes according to the ultraviolet transmittance, and the control means acquires the ultraviolet transmittance in each operation mode using the transmittance acquiring means, and controls the flow rate adjusting means and the ultraviolet reactor so that the treatment flow rate and the ultraviolet irradiation amount are determined for the determined operation mode.

Preferably, the control means determines the appropriate operation mode using the ultraviolet transmittance acquired from the transmittance acquisition means as a judgment criterion in addition to the judgment criteria (1) and/or (2).

Preferably, the plurality of operating modes include a first mode and a second mode, and the processing flow rate is set so that when the ultraviolet transmittance is equal to or greater than a predetermined value, the processing flow rate is greater in the first mode than in the second mode, and when the ultraviolet transmittance is less than the predetermined value, the processing flow rate is greater in the second mode than in the first mode.

1 is a conceptual diagram showing a ballast water treatment device 10 according to one embodiment of the present invention and a state in which the ballast water treatment device is installed in a ballast system 1 of a ship. 2 is a block diagram showing the main configuration of the ballast water treatment device 10 of FIG. 1. 11 is a diagram showing tank retention times in a first mode M1 and a second mode M2. 11 is a graph showing the relationship between ultraviolet transmittance and processing flow rate defined in a first mode M1 and a second mode M2. 2 is a flowchart showing an algorithm for the ballast water treatment device 10 of FIG. 1 to determine an appropriate operating mode. 2 is a diagram showing a flow path during ballasting operation of the ballast device 1 of FIG. 1. 2 is a diagram showing the flow paths during de-ballast operation of the ballast device 1 of FIG. 1. FIG. 2 is a diagram showing a flow path during preliminary operation of the ballast device 1 of FIG. 1.

The following describes the embodiments of the present invention. The various features shown in the embodiments below can be combined with each other. In addition, each feature can be an invention independently.

1. Configuration of the ballast device 1 FIG. 1 is a schematic diagram showing a state in which a ballast water treatment device 10 as a liquid treatment device according to an embodiment of the present invention is introduced into a ballast device 1 of a ship. The ballast device 1 of the present application includes a ballast tank 2 and a ballast pump 3, and the ballast pump 3 injects and discharges ballast water into and from the ballast tank 2. The operation of taking in outside water such as seawater from a sea chest SC1 into the ship and injecting it into the multiple ballast tanks 2 is called a ballast operation, and the operation of discharging the ballast water stored in the ballast tank 2 from an outside discharge port SC2 is called a de-ballast operation. In addition, with regard to "ballast water" in this specification, all water taken into the ship is expressed as "ballast water", regardless of whether it is before being introduced (flowing into) the ballast tank 2 or after being discharged (flowing out) from the ballast tank 2. The ballast water taken into the ship includes seawater, fresh water, brackish water, and the like.

As shown in FIG. 1, the ballast device 1 includes lines La to Le that connect the various components and allow the ballast water to flow, and on-off valves Va to Vf that are provided on these lines. Here, "line" is a general term for lines such as flow paths, pathways, and pipelines through which fluids can flow.

To explain the connection relationship of each line in detail, line La is a line that connects the sea chest SC1 and the ballast pump 3, and has an on-off valve Va. Line Lb and line Lc are lines that connect the ballast pump 3 and the ballast tank 2. Since the ballast water treatment device 10 is disposed between the ballast pump 3 and the ballast tank 2, the upstream side of the ballast water treatment device 10 is called line Lb, and the downstream side of the ballast water treatment device 10 is called line Lc. Line Lb has an on-off valve Vb, and line Lc has on-off valves Vc and Vd. Lines La to Lc are collectively referred to as the ballast lines.

One end of line Ld is connected to line La between the on-off valve Va and the ballast pump 3, and the other end is connected to line Lc on the ballast tank 2 side of the on-off valve Vc. An on-off valve Ve is installed in line Ld. Line Ld is used during de-ballast operation and is also called the de-ballast line. One end of line Le is connected to line Lc between the ballast water treatment device 10 and the on-off valve Vc, and the other end is connected to the overboard discharge port SC2. An on-off valve Vf is installed in line Le.

The configuration of the ballast system 1 described above is merely one example of a ballast system into which the ballast water treatment device 10 according to the present invention can be installed, and the ballast water treatment device 10 described below can be applied to a ballast system of any configuration.

2. Configuration of the ballast water treatment device 10 Next, the configuration of the ballast water treatment device 10 will be described. The ballast water treatment device 10 is introduced to treat the ballast water taken into the ship and the ballast water discharged from the ship to reduce the content of microorganisms and foreign matter contained in the ballast water. As shown in Fig. 1, the ballast water treatment device 10 of this embodiment is provided between the ballast pump 3 and the ballast tank 2 (or the overboard discharge port SC2). Here, regarding the flow path of the ballast water treatment device 10, the connection part on the ballast pump 3 side connected to the line Lb is referred to as the upstream connection part P1, and the connection part on the ballast tank 2 side connected to the line Lc is referred to as the downstream connection part P2.

The ballast water treatment device 10 of this embodiment includes, as purification means, a filtration device 11 that filters the ballast water using a filter, and an ultraviolet reactor 12 that irradiates the ballast water with ultraviolet light to sterilize microorganisms. As shown in FIG. 2, the ballast water treatment device 10 also includes a flow meter 13, an ultraviolet sensor 14, an input device 15, a transmittance acquisition means 16, a salinity concentration measurement means 17, a determination result output means 18, and a control means 19. Note that any known configuration can be applied to the filtration device 11, and the filtration device 11 can also be omitted.

In addition, as shown in FIG. 1, the ballast water treatment device 10 includes a first line L1 to a fifth line L5 that connect the various components and allow the ballast water to flow, on-off valves V1 to V4 installed on these lines, and a flow control valve FCV as a flow control means.

The first line L1 is a line (bypass line) that bypasses the purification means (filter 11 and ultraviolet reactor 12) and connects the upstream connection part P1 and the downstream connection part P2, and has an on-off valve V1. The second line L2 is a line that connects the first line L1 and the filter 11, and has an on-off valve V2. The third line L3 is a line that connects the filter 11 and the ultraviolet reactor 12, and has an on-off valve V3. The fourth line L4 has one end connected to a position downstream of the connection position of the first line L1 with the second line L2 and upstream of the on-off valve V1, and the other end connected to a position downstream of the on-off valve V3 of the third line L3. The fourth line L4 has an on-off valve V4. The fifth line L5 has one end connected to the ultraviolet reactor 12 and the other end connected to a position downstream of the on-off valve V1 of the first line L1. The fifth line L5 is provided with a flow meter 13 and a flow control valve FCV whose opening can be adjusted (see also FIG. 2).

The ultraviolet reactor 12 is configured with multiple ultraviolet lamps 12a (see FIG. 2) arranged inside a treatment tank (not shown). The ultraviolet reactor 12 sterilizes microorganisms by irradiating the ballast water flowing through the treatment tank with ultraviolet light from the ultraviolet lamps 12a. The ultraviolet reactor 12 of this embodiment is capable of adjusting the intensity of the ultraviolet light irradiated to the ballast water by controlling the on/off and/or supply of power to each ultraviolet lamp 12a.

The flowmeter 13 measures the flow rate of ballast water flowing through the ultraviolet reactor 12. In this embodiment, the flowmeter 13 is provided on the fifth line L5, but it may be provided at another position on the flow path of the ballast water when the sterilization treatment is performed by the ultraviolet reactor 12. By adjusting the opening of the flowmeter 13 and the above-mentioned flow control valve FCV, it is possible to adjust the flow rate of ballast water flowing through the ballast water treatment device 10 (hereinafter referred to as the treatment flow rate).

The ultraviolet sensor 14 is installed in the ultraviolet reactor 12 and measures the illuminance of ultraviolet light from the ultraviolet lamp 12a through the ballast water. The ultraviolet irradiance, which is the amount of ultraviolet light irradiated per unit flow rate, is calculated from the flow rate of the ballast water measured by the flowmeter 13 and the illuminance of ultraviolet light measured by the ultraviolet sensor 14.

The input device 15 is a device that accepts various inputs from users such as crew members. Examples of the input device 15 include a mouse connected to an information processing device such as a personal computer, a display that allows input via a keyboard or touch panel, and even a voice input device. However, any device can be used as long as it is capable of receiving various inputs from the user. Here, the various inputs accepted from the user include information on the current position of the ship, information on the total amount of ballast water that needs to be stored, information on the ship's destination, information on the time from when the ship enters port until when it departs port, information on the (estimated) time from when the ship is at anchor until when it arrives at its destination port, etc.

The allowable discharge time from when the anchored ship leaves port until when it arrives at its destination port can be calculated, which is the allowable discharge time from when the treated ballast water is stored in the ballast tank 2 until when it is discharged. Therefore, the input device 15 of this embodiment functions as an allowable discharge time acquisition means for acquiring the allowable discharge time from when the treated ballast water is stored in the ballast tank 2 until when it is discharged. The allowable discharge time is important because, while it has little impact if the ship's travel time to the next port is long, if the travel time to the next port is short, a problem occurs in which the ballast water cannot be discharged at the port and cargo cannot be handled. The input device 15 is preferably installed in a ballast controller that controls the operation of the ballast device 1.

The transmittance acquisition means 16 acquires the ultraviolet transmittance of the ballast water flowing through the ultraviolet reactor 12. In this embodiment, the transmittance acquisition means 16 is a transmittance measurement sensor capable of measuring the ultraviolet transmittance of the ballast water. The transmittance measurement sensor does not need to be installed on the flow path of the ballast water in the ballast water treatment device 10, but is installed at any position on the ship where seawater can be easily taken in.

The salinity measuring means 17 measures the salinity of the ballast water flowing through the ballast water treatment device 10. In this embodiment, the salinity measuring means 17 is an electrical conductivity meter that measures the electrical conductivity of the ballast water. As shown in FIG. 1, the salinity measuring means 17 is provided, for example, in the first line L1 (bypass line). However, the salinity measuring means 17 does not need to be provided on the flow path of the ballast water in the ballast water treatment device 10, and the salinity measuring means 17 may be installed in any position that allows easy intake of seawater into the ship.

The salinity measuring means 17 is used to identify a water area determined by its salinity. Specific water areas include, for example, seawater, brackish water, and freshwater. In each of the operation modes M1 to M3 described below, a predetermined amount of ultraviolet radiation is set for each water area because the ultraviolet resistance of microorganisms varies depending on the water area. Then, the control means 19 identifies the water area from the salinity obtained by the salinity measuring means 17, and can perform purification processing with an appropriate amount of ultraviolet radiation depending on the water area.

The determination result output means 18 is for presenting to the user the appropriate operating mode determined by the determination unit 92 of the control means 19. As the determination result output means 18, for example, a display device such as a display is used. If the input device 15 is equipped with a display, it is also preferable to share this.

The control means 19 adjusts the flow rate of ballast water flowing through the ballast water treatment device 10 by controlling the opening and closing of the above-mentioned on-off valves Va to Vf, on-off valves V1 to V4, and flow control valve FCV. The control means 19 also adjusts the amount of ultraviolet light irradiated onto the ballast water by controlling the output of the ultraviolet lamp 12a of the ultraviolet reactor 12. The adjustment of the flow rate of ballast water by controlling the opening and closing of the flow control valve FCV and the adjustment of the amount of ultraviolet light irradiated onto the ballast water by controlling the output of the ultraviolet reactor 12 are performed in one operation mode selected from the first mode M1 to the third mode M3 described below. Specifically, as shown in FIG. 2, the control means 19 includes an information acquisition unit 90, a memory unit 91, a determination unit 92, and an operation control unit 93.

The information acquisition unit 90 acquires the flow rate of the ballast water flowing from the flowmeter 13, acquires various inputs from the crew entered into the input device 15, and acquires the ultraviolet transmittance of the ballast water from the transmittance acquisition means 16. The information acquisition unit 90 also acquires the salinity of the ballast water from the salinity measurement means 17.

The memory unit 91 has a function of storing various data. The memory unit 91 stores the processing flow rate and the amount of ultraviolet irradiation specified for each ultraviolet transmittance in each of the first mode M1 to the third mode M3. Note that the processing flow rate and the amount of ultraviolet irradiation specified for each ultraviolet transmittance in each operating mode differ depending on the water area. The memory unit 91 also stores the tank retention times T11 and T12 in the first mode M1 and the tank retention time T2 in the second mode M2, which will be described later.

The determination unit 92 determines an appropriate operating mode based on the information acquired by the information acquisition unit 90 and the information stored in the memory unit 91.

The operation control unit 93 controls the opening of the flow control valve FCV and the intensity of the ultraviolet lamp 12a of the ultraviolet reactor 12 in one of the operation modes, first mode M1 to third mode M3. This adjusts the treatment flow rate of the ballast water and the amount of ultraviolet light irradiated onto the ballast water.

The control means 19 of the above configuration can be specifically configured, for example, by an information processing device including a CPU, a memory (e.g., a flash memory), an input unit, and an output unit. Processing by each of the above-mentioned components of the control means 19 configured by the information processing device is performed by the CPU reading and executing a program stored in the memory. As the information processing device, for example, a personal computer, a PLC (programmable logic controller), or a microcomputer is used. However, some of the functions of the control means 19 may be configured to be executed on a cloud connected by any communication means.

3. Operation of the Ballast Water Treatment Device 10 The ballast water treatment device 10 of this embodiment has three operation modes, a first mode M1 to a third mode M3, as a plurality of operation modes. When performing a ballast water purification process in a ballasting operation, the ballast water treatment device 10 first determines an appropriate operation mode through a mode determination process, and then performs the purification process in the determined operation mode.

In each operation mode, the processing flow rate and UV irradiation amount are specified for each water body and for each UV transmittance, and the processing flow rate and UV irradiation amount for each UV transmittance are stored in the memory unit 91. The control means 19 controls the opening of the flow control valve FCV and the intensity of the UV lamp 12a of the UV reactor 12 so that the purification process is performed at the processing flow rate and UV irradiation amount specified for each operation mode. Note that in all operation modes, the processing flow rate is set to be higher as the UV transmittance is higher. This is because, even with the same output of the UV lamp 12a, the UV irradiation amount increases as the UV transmittance is higher.

<About each driving mode>
In the present embodiment, the first mode M1 and the second mode M2 are operation modes that comply with the emission regulations set by the United States Coast Guard (USCG). That is, the first mode M1 and the second mode M2 are both operation modes that have been type-approved by an agency designated by the United States Coast Guard (USCG). On the other hand, the third mode M3 is an operation mode that complies with the emission regulations set by the International Maritime Organization (IMO) and is an operation mode that has been type-approved by an agency designated by the International Maritime Organization (IMO). Therefore, when the ship is sailing to the United States or its nearby waters (hereinafter referred to as sea area A), the ship is operated in the first mode M1 or the second mode M2, and when the ship is not sailing to sea area A, the ship is operated in the third mode M3, thereby complying with each emission regulation.

In addition, the United States Coast Guard (USCG) discharge regulations stipulate that once stored, ballast water must not be discharged until a specified time has elapsed, and the time during which it must not be discharged is called the "tank retention time" or "holding time." Therefore, in first mode M1 and second mode M2, which are some of first mode M1 to third mode M3, the time from when the treated ballast water is stored in the ballast tank 2 until it is discharged (hereinafter referred to as the allowable discharge time) must be longer than the specified tank retention time. And if the allowable discharge time is shorter than the tank retention time, the ballast water cannot be discharged until the tank retention time has elapsed, even if the ship arrives at its destination port.

The tank retention time is different between the first mode M1 and the second mode M2. In the first mode M1, the tank retention time is also different between the freshwater/brackish water area as the first water area and the seawater area as the second water area (on the other hand, in the second mode M2, the tank retention time is the same regardless of the water area). Here, as shown in FIG. 3, the tank retention time in the freshwater/brackish water area in the first mode M1 is T11, the tank retention time in the seawater area in the first mode M1 is T12, and the tank retention time in the second mode M2 is T2. These tank retention times T11 and T12 in the first mode M1 and the tank retention time T2 in the second mode M2 are stored in the memory unit 91. In this embodiment, the tank retention time T11 in the brackish/freshwater area in the first mode M1 is longer than the tank retention time T12 in the seawater area in the same mode (T11>T12). In addition, the tank retention time T2 in the second mode M2 is shorter than the tank retention time T12 in the seawater area in the first mode M1 (T12>T2). However, compared to the difference between the tank retention time T11 in the brackish/freshwater area in the first mode M1 and the tank retention time T12 in the seawater area in the same mode (the difference between T11 and T12), the difference between the tank retention time T12 in the seawater area in the first mode M1 and the tank retention time T2 in the second mode M2 is small.

In addition, as shown in FIG. 4, when comparing the first mode M1 and the second mode M2, the processing flow rate is set to be higher in the first mode M1 than in the second mode M2 when the ultraviolet transmittance is equal to or greater than the predetermined value Ux, and the processing flow rate is set to be higher in the second mode M2 than in the first mode M1 when the ultraviolet transmittance is less than the predetermined value Ux. In other words, the predetermined value Ux of the ultraviolet transmittance is the value at which the processing flow rates of the first mode M1 and the second mode M2 switch between large and small. Note that the processing flow rates corresponding to the ultraviolet transmittances of the first mode M1 and the second mode M2 are different in freshwater/brackish water and seawater (the processing flow rate is higher in seawater). However, the relationship between the UV transmittance and the processing flow rate in the first mode M1 and the second mode M2 shown in FIG. 4, and the fact that the processing flow rate in the first mode M1 and the second mode M2 switches between large and small at a predetermined value Ux, are the same in both freshwater/brackish water and seawater (FIG. 4 is a conceptual diagram, and the predetermined value Ux at which the processing flow rate of the UV transmittance switches does not need to be the same in freshwater/brackish water and seawater).

Below, an example of an algorithm for determining an appropriate operating mode will be described with reference to FIG. 5. The mode determination process is started when a crew member or other person requests a mode determination, or when the ship enters port.

<Mode Determination Process>
In the mode determination process, first, in step S1, the information acquisition unit 90 of the control means 19 acquires information on the next destination of the ship inputted to the input device 15. Here, the memory unit 91 stores information on whether the port of the destination belongs to sea area A, and the determination unit 92 determines whether the destination belongs to sea area A or not based on the inputted information on the destination of the ship and this information. If the destination is not sea area A, the determination unit 92 determines that the appropriate operating mode is the third mode M3, and ends the mode determination process. If the destination is sea area A, the process proceeds to the next step S2. It is also possible to configure the input device 15 to directly input whether the destination belongs to sea area A or not.

Next, in step S2, the information acquisition unit 90 acquires the salinity of the circulating ballast water measured by the salinity measurement means 17. The determination unit 92 identifies the current water area from the salinity acquired by the information acquisition unit 90, and determines whether the current water area is a seawater area. If the current water area is a seawater area, the determination unit 92 skips the next step S3 and proceeds to step S4. On the other hand, if the current water area is not a seawater area, that is, if the current water area is a brackish water area or a freshwater area, the determination unit 92 proceeds to the next step S3.

Next, in step S3, the information acquisition unit 90 acquires the allowable discharge time input to the input device 15. The information acquisition unit 90 also reads out the tank retention time T11 of the first mode M1 in brackish/freshwater areas (longer than the tank retention time T2 of the second mode M2) from the memory unit 91. If the allowable discharge time is shorter than the tank retention time T11 of the first mode M1, that is, if operation in the first mode M1 would require ballast water to be retained for longer than the allowable discharge time, the determination unit 92 determines that the appropriate operating mode is the second mode M2, which has a shorter tank retention time, and ends the mode determination process. If the allowable discharge time is longer than the tank retention time T11 of the first mode M1, the process proceeds to the next step S4.

In step S2, if the current water area is seawater, step S3 is skipped and the process proceeds to step S4 because the difference between the tank retention time T12 in seawater in the first mode M1 and the tank retention time T2 in the second mode M2 is small. In other words, even if the first mode M1, which has a long tank retention time, is selected, ballast water can be discharged after waiting for several hours, and in seawater, there is little benefit to executing step S3, which determines the operating mode using the tank retention time as a determination criterion. In particular, if the tank retention time T12 in seawater in the first mode M1 is equal to or less than the standard sailing time of the ship, the tank retention time T12 will have elapsed by the time the ballast water is discharged, and there is no need to execute step S3.

On the other hand, when the water area is a freshwater or brackish water area, there is a large difference between the tank retention time T11 in the first mode M1 and the tank retention time T2 in the second mode M2 (T11 >> T2). Therefore, if the first mode M1 is selected when the allowable discharge time is short, even when the ship arrives at the next port, it will not be able to discharge ballast water for a long time, making it impossible to carry out cargo handling. Therefore, it is particularly preferable to execute step S3 when the water area is a freshwater or brackish water area.

Next, in step S4, the information acquisition unit 90 acquires the ultraviolet transmittance of the ballast water taken at the current location from the transmittance acquisition means 16. The determination unit 92 compares the ultraviolet transmittance acquired from the transmittance acquisition means 16 with a predetermined value Ux at which the processing flow rate in the current water area is switched between the first mode M1 and the second mode M2 (see FIG. 4). If the ultraviolet transmittance is equal to or greater than the predetermined value Ux in the current water area, the determination unit 92 determines that the appropriate operating mode is the first mode M1, which has a high processing flow rate in this range (see FIG. 4), and ends the mode determination process. On the other hand, if the ultraviolet transmittance is less than the predetermined value Ux in the current water area, the determination unit 92 determines that the appropriate operating mode is the second mode M2, which has a high processing flow rate in this range (see FIG. 4), and ends the mode determination process.

After it is determined that one of the modes is an appropriate operation mode by steps S1 to S4 of the mode determination process described above, the control means 19 presents the determined appropriate operation mode to a user such as a crew member through the determination result output means 18. The user refers to the determination result presented by the determination result output means 18 and selects which operation mode to actually perform the ballasting operation, and inputs the operation mode to be performed through the input device 15. The operation control unit 93 of the control means 19 starts the ballasting operation described below according to the input operation mode. It is also possible to configure the system so that the determined appropriate operation mode is not displayed on the display means, but is automatically selected and the ballasting operation is started. In addition, the determination result output means 18 may display not only the determination result determined to be appropriate, but also, for example, the difference between the allowable discharge time in step S3 and the tank retention time in each operation mode M1, M2, and the difference in the processing flow rate in step S4. In this case, if the difference between the allowable discharge time and the tank retention time or the difference in the processing flow rate for each operation mode is small, the user can select an operation mode other than the operation mode determined to be appropriate based on other conditions other than those described above.

<Purification process>
Next, the purification process according to the determined operation mode will be described. Each operation of the purification process is controlled by the control means 19, but some or all of the operations can also be performed manually by the crew.

Figure 6 is a diagram showing the flow path of ballast water during ballast operation by the ballast device 1. Lines La to Lc shown in thick lines are the flow paths through which ballast water flows, and during this operation, the on-off valves Va to Vd of the ballast device 1 are opened, and the other on-off valves Ve and Vf are closed. At this time, in the ballast water treatment device 10, the operation control unit 93 of the control means 19 controls the on-off valves V2 and V3 and the flow control valve FCV to be opened, and the on-off valves V1 and V4 to be closed. As a result, the ballast water flows through a part of the first line L1, the second line L2, the third line L3, and the fifth line L5, and flows through the filtration device 11 and the ultraviolet reactor 12. At this time, the operation control unit 93 also outputs a start command for these filtration device 11 and the ultraviolet reactor 12. The operation control unit 93 controls the opening of the flow control valve FCV and the intensity of the ultraviolet lamp 12a to adjust the treatment flow rate of the ballast water and the amount of ultraviolet radiation applied to the ballast water to values specified in the operation mode selected in the mode determination process. Through such control, the ballast water is purified by flowing through the filtration device 11 and the ultraviolet reactor 12, and is stored in the ballast tank 2.

Figure 7 is a diagram showing the flow path during the de-ballast operation of the ballast device 1. A part of line La, line Lb, a part of line Lc, line Ld, and line Le shown by thick lines are the flow paths through which ballast water flows during the de-ballast operation. During this operation, the on-off valves Vb, Vd to Vf are opened, and the other on-off valves Va and Vc are closed. At this time, in the ballast water treatment device 10, the operation control unit 93 of the control means 19 controls to open the on-off valve V4 and the flow control valve FCV, and to close the on-off valves V1 to V3. As a result, the ballast water flows through a part of the first line L1, the fourth line L4, a part of the third line L3, and the fifth line L5, bypasses the filtration device 11, and flows only through the ultraviolet reactor 12. The operation control unit 93 also outputs a start-up command for the ultraviolet reactor 12. By flowing the ballast water stored in the ballast tank 2 through the ultraviolet reactor 12, it is possible to purify microorganisms and foreign matter that have proliferated during storage. The ballast water discharged overboard is not filtered by the filter 11 because the ballast water in the ballast tank 2 is filtered once during ballasting operation.

4. Effects As described above, the ballast water treatment device 10 of this embodiment includes the salinity concentration measuring means 17 and the input device 15 as the allowable discharge time acquiring means, and the control means 19 determines an appropriate operation mode based on a comparison of (1) the salinity measured by the salinity concentration measuring means 17 and (2) the allowable discharge time acquired by the input device 15 and the tank retention time as a determination criterion. This makes it possible to operate the ballast water treatment device 10 in an appropriate operation mode according to the situation.

Specifically, in step S2, the control means 19 of the ballast water treatment device 10 identifies the water area from the salinity measured by the salinity measurement means 17. Then, in steps S2 and S3, if the water area is a freshwater area or a brackish water area, the allowable discharge time acquired by the input device 15 is compared with the tank retention time T11 of the first mode M1 in the brackish water/freshwater area read from the memory unit 91, and the comparison result is used as the criterion for determining the operation mode. On the other hand, if the water area is a seawater area, such a comparison is not performed and the comparison result is not used as the criterion for determining the operation mode. In summary, the control means 19 identifies the brackish water/freshwater area and the seawater area using the above (1) as the criterion, and determines the appropriate operation mode only in the brackish water/freshwater area using the above (2) as the criterion. This makes it possible to avoid a situation in which ballast water cannot be discharged for a long period of time even at the next port in a freshwater or brackish water area where the tank retention time is long. On the other hand, in a seawater area where the tank retention time is short, the influence of the tank retention time is not large. Therefore, by determining the operation mode based on other conditions, specifically, the ultraviolet transmittance in step S4, it is possible to determine that the operation mode with a high treatment flow rate is the appropriate operation mode depending on the ultraviolet transmittance of the ballast water being treated, making it possible to quickly complete the ballasting operation.

5. Modifications The present invention can also be implemented in the following aspects.

In the above embodiment, a transmittance measurement sensor disposed at a location separate from the ultraviolet reactor 12 was used as the transmittance acquisition means 16 for acquiring the transmittance of the ballast water. However, instead of installing a transmittance measurement sensor as the transmittance acquisition means 16, it is also possible to have the control means 19 calculate the ultraviolet transmittance during preliminary operation (see FIG. 8) in which the ballast water is discharged without being stored in the ballast tank 2. Specifically, during preliminary operation, the ultraviolet lamp 12a is turned on and the intensity of the ultraviolet lamp 12a is measured by the ultraviolet sensor 14. This makes it possible to have the control means 19 calculate the ultraviolet transmittance from the intensity of the ultraviolet lamp 12a and the illuminance of the ultraviolet light measured by the ultraviolet sensor 14.

In the above embodiment, as shown in FIG. 5, the mode determination process has four steps, S1 to S4. However, the mode determination process may not have one or more of these steps S1 to S4. For example, if there is no difference in the processing flow rate for each UV transmittance between the first mode M1 and the second mode M2, step S4 may not be included. In this case, if the allowable discharge time in step S3 is also longer than the tank retention time for each operation mode M1, M2, operation may be performed in either mode. In such a case, it is preferable to notify the user, such as a crew member, by the determination result output means 18 and to accept the operation mode to be executed from the user by the input device 15.

In the above embodiment, the tank retention time of the first mode M1 differs between the freshwater/brackish water area as the first water area and the seawater area as the second water area (T11, T12). However, the tank retention time of the first mode M1 may differ between the three water areas, i.e., the freshwater area, the brackish water area, and the seawater area. In this case, the lower the salinity of the water area, the more resistant microorganisms are to ultraviolet light, so the tank retention time of the freshwater area is the longest, and the tank retention time of the seawater area is the shortest. In this case, the first water area is the freshwater area, the second water area is the brackish water area and the seawater area, and the allowable discharge time acquired by the input device 15 (allowable discharge time acquisition means) is compared with the tank retention time of each operation mode in the freshwater area only in the freshwater area to determine the operation mode (execute the above-mentioned step S3). Even with this configuration, it is possible to avoid a situation in which ballast water cannot be discharged for a long period of time in the freshwater area where the tank retention time is long, while determining an appropriate operation mode based on other conditions in the brackish water area and the seawater area. Furthermore, even if water areas are divided into four or more areas based on salinity, the same effect can be achieved by performing step S3 described above only in some of the water areas with low salinity.

In the above embodiment, there are two operating modes that comply with the discharge regulations set by the United States Coast Guard (USCG), i.e., operating modes with a set tank retention time, the first mode M1 and the second mode M2. However, there may be three or more operating modes that comply with the discharge regulations set by the United States Coast Guard (USCG). In this case, too, the control means 19 determines the appropriate operating mode based on the comparison of the salinity measured by the salinity measurement means 17 and the allowable discharge time acquired by the input device 15 with the tank retention time as a judgment criterion, thereby making it possible to operate the ballast water treatment device 10 in an appropriate operating mode according to the situation.

In the above embodiment, the operation mode was determined based on the salinity concentration, the allowable discharge time compared to the tank retention time, and the ultraviolet transmittance as the criteria. However, the operation mode may be determined based on other conditions. For example, if the lower limit of the ultraviolet transmittance that can be processed differs depending on the operation mode, the appropriate operation mode may be determined based on the comparison of the ultraviolet transmittance of the ballast water with the lower limit in each operation mode as a criterion. In addition, if the power consumption differs depending on the operation mode, the appropriate operation mode may be determined based on the power consumption as a criterion. Furthermore, if the processing flow rate for each ultraviolet transmittance differs depending on the operation mode, the appropriate operation mode may be determined based on the comparison of the allowable processing time that can be spent on the ballast operation obtained from the crew, etc. with the required processing time calculated from the processing flow rate in each operation mode as a criterion.

1: Ballast device 2: Ballast tank 3: Ballast pump 10: Ballast water treatment device 11: Filtration device 12: Ultraviolet reactor 12a: Ultraviolet lamp 13: Flow meter 14: Ultraviolet sensor 15: Input device (allowable discharge time acquisition means)
16: Permeability acquisition means 17: Salinity concentration measurement means 18: Judgment result output means 19: Control means 90: Information acquisition unit 91: Memory unit 92: Judgment unit 93: Operation control unit A: Sea area FCV: Flow rate control valve L1: First line L2: Second line L3: Third line L4: Fourth line L5: Fifth line La to Le: Line M1: First mode M2: Second mode M3: Third mode P1: Upstream connection part P2: Downstream connection parts S1 to S4: Step SC1: Sea chest SC2: Overboard discharge outlet T11, T12, T2: Tank retention time Ux: Predetermined permeability V1 to V4: On-off valves Va to Vf: On-off valves

Claims (5)

A ballast water treatment device that purifies and treats circulating ballast water,
an ultraviolet reactor capable of adjusting the amount of ultraviolet irradiation;
A control means for controlling the ballast water treatment device in one operation mode selected from a plurality of operation modes;
A salinity measuring means for measuring the salinity of the ballast water flowing through the vessel;
and an allowable discharge time acquisition means for acquiring an allowable discharge time from when the ballast water treated by the ultraviolet reactor is stored in the ballast tank until when the ballast water is discharged,
For each of the plurality of operation modes, a treatment flow rate and an ultraviolet irradiation amount are specified for each water area and for each ultraviolet transmittance, and a tank retention time for which the treated ballast water must be retained in the ballast tank is set,
The control means identifies a water area based on the salinity measured by the salinity measurement means,
The control means further determines, when the permissible discharge time acquired by the permissible discharge time acquisition means is shorter than the tank retention time of an operating mode among the plurality of operating modes that has the longest tank retention time, that the operating mode with the shortest tank retention time is an appropriate operating mode. The ballast water treatment device according to claim 1 ,
The water area includes a first water area and a second water area having a higher salinity than the first water area,
The control means, in the first water area, when the permissible discharge time acquired by the permissible discharge time acquisition means is shorter than the tank retention time of an operating mode among the plurality of operating modes having the longest tank retention time, determines that the operating mode having the shortest tank retention time is an appropriate operating mode . The ballast water treatment device according to claim 1 or 2,
The ballast water is then passed through the passage of ultraviolet light.
The control means, when the permissible discharge time acquired by the permissible discharge time acquisition means is the same as or longer than the tank retention time of the operating mode having the longest tank retention time among the multiple operating modes, determines an appropriate operating mode using the ultraviolet transmittance acquired from the transmittance acquisition means as a judgment criterion. The ballast water treatment device according to claim 1 or 2,
A flow rate adjusting means for adjusting the treatment flow rate of the circulating ballast water;
and a transmittance acquisition means for acquiring an ultraviolet transmittance of the circulating ballast water ,
The control means acquires the ultraviolet transmittance using the transmittance acquisition means in each operating mode, and controls the flow rate adjustment means and the ultraviolet reactor so as to achieve the treatment flow rate and the ultraviolet irradiation amount determined in the determined operating mode. The ballast water treatment device according to claim 4,
The plurality of operation modes includes a first mode and a second mode,
When the ultraviolet ray transmittance is equal to or greater than a predetermined value, the processing flow rate in the first mode is greater than that in the second mode,
The ballast water treatment device, wherein the treatment flow rate in the second mode is set to be higher than that in the first mode when the ultraviolet transmittance is less than the predetermined value.