阅读说明：本技术 压载水处理系统以及具备该系统的船舶 (Ballast water treatment system and ship provided with same ) 是由 荻须俊辅 于 2019-04-25 设计创作，主要内容包括：压载水处理系统具有：压载水处理机(12),对注水到压载水舱的压载水进行电解而净化；造水机(16),由海水制造淡水；盐水罐(26),回收并贮存通过造水机(16)制造淡水时产生的高浓度盐水；盐水供给配管(39),将盐水罐(26)内的高浓度盐水向压载水处理机(12)供给；以及取水管(15),将船外水向压载水处理机(12)供给,在将淡水区域以及咸淡水区域中的船外水向压载水舱注水时,将盐水罐(26)内的高浓度盐水向压载水处理机(12)供给。(The ballast water treatment system comprises: a ballast water treatment machine (12) for electrolyzing and purifying the ballast water injected into the ballast water tank; a fresh water generator (16) for generating fresh water from seawater; a brine tank (26) that recovers and stores high-concentration brine generated when fresh water is produced by the water producing machine (16); a brine supply pipe (39) for supplying the high-concentration brine in the brine tank (26) to the ballast water treatment machine (12); and a water intake pipe (15) for supplying the ballast water treatment machine (12) with the overboard water, and for supplying the ballast water treatment machine (12) with the high-concentration brine in the brine tank (26) when the ballast water tank is filled with the overboard water in the fresh water area and the brackish fresh water area.)

1. A ballast water treatment system comprising:

a ballast water treatment machine for electrolyzing and purifying the ballast water injected into the ballast water tank;

a fresh water generator for generating fresh water from seawater;

a brine tank recovering and storing high concentration brine generated when fresh water is produced by the fresh water generator;

a brine supply pipe for supplying the high-concentration brine in the brine tank to the ballast water treatment machine;

a water intake pipe for supplying the ballast water to the ballast water treatment machine; and

and a pump for supplying the high-concentration brine in the brine tank to the ballast water treatment machine when the ballast water tank is filled with overboard water as ballast water.

2. The ballast water treatment system according to claim 1,

a bypass pipe is provided in the brine recovery pipe, the brine recovery pipe connecting the brine outlet of the fresh water generator and the brine inlet of the brine tank,

a thickener is provided in the bypass pipe, and increases a salt concentration of the high-concentration brine discharged from the brine outlet.

3. The ballast water treatment system according to claim 1 or 2,

the ballast water treatment system comprises:

an injection pipe for injecting overboard water into the brine supply pipe; and

a flow rate adjuster for adjusting the flow rate of the extra-marine water injected into the brine supply pipe through the injection pipe,

the concentration of the high-concentration brine supplied from the brine supply pipe to the ballast water treatment machine is adjusted by the overboard water.

4. The ballast water treatment system according to any one of claims 1 to 3,

the ballast water treatment system comprises:

a flow rate sensor that detects a flow rate of the overboard water supplied to the ballast water treatment machine through the intake pipe; and

and a control means for controlling the flow rate of the high-concentration brine supplied from the brine tank to the ballast water treatment machine based on the flow rate of the overboard water detected by the flow rate sensor.

5. The ballast water treatment system according to claim 4,

the ballast water treatment system comprises:

an injection pipe for injecting overboard water into the brine supply pipe; and

a flow rate adjuster for adjusting the flow rate of the extra-marine water injected into the brine supply pipe through the injection pipe,

the control means controls the flow rate adjuster to adjust a mixing ratio of the overboard water supplied to the brine supply pipe and the high concentration brine discharged from the brine tank, based on a flow rate of the overboard water supplied to the ballast water treatment machine and a salinity of the high concentration brine.

6. A ballast water treatment method comprises the following steps:

electrolyzing and purifying the ballast water injected into the ballast water tank by a ballast water processor;

producing fresh water from seawater by a fresh water generator;

storing high-concentration brine generated when fresh water is produced by the fresh water generator in a brine tank; and

when the ballast water tank is filled with overboard water as ballast water, the high-concentration brine in the brine tank is supplied to the ballast water treatment machine.

7. The ballast water treatment method according to claim 6,

the ballast water treatment method comprises the following steps: the salinity of the high-concentration brine supplied from the fresh water generator to the brine tank is increased by a concentrator.

8. The ballast water treatment method according to claim 6 or 7,

the ballast water treatment method comprises the following steps: the high-concentration brine supplied from the brine tank to the ballast water treatment machine is injected into the overboard water, and the flow rate of the overboard water injected into the high-concentration brine is adjusted by a flow rate adjuster.

9. A marine vessel having:

a hull provided with a ballast water treatment machine for electrolyzing and purifying ballast water injected into a ballast water tank;

the water generator is arranged on the ship body and used for generating fresh water from seawater;

a brine tank provided in the hull, recovering and storing high-concentration brine generated when fresh water is produced by the fresh water generator;

a brine supply pipe provided in the hull and configured to supply the high-concentration brine in the brine tank to the ballast water treatment machine;

a water intake pipe provided in the hull and configured to supply the ballast water to the ballast water treatment machine; and

and a pump provided in the hull, for supplying the high-concentration brine in the brine tank to the ballast water treatment machine when the ballast water tank is filled with the overboard water as the ballast water.

Technical Field

The present invention relates to a ballast water treatment technique for purifying ballast water and a ship provided with the technique.

Background

In ships such as crude oil tankers and cargo carriers, seawater at ports is loaded into ballast tanks when the ships are left empty to stabilize the ship body. The seawater charged into the ballast water tank as a counterweight of the ship is discharged overboard at the port where the cargo is loaded. Ballast water, which is seawater filled in a ballast tank, contains aquatic organisms, bacteria, microorganisms, and the like, and if the ballast water is directly discharged at a port where cargo is loaded, there is a risk that the aquatic organisms contained in the ballast water may act as foreign species at the port and affect an ecosystem.

Therefore, in order to purify the ballast water taken from the outside of the ship, the ballast water is sent to a filter, and organisms and garbage generally larger than about 50 μm are removed as foreign matter, and further, the organisms that cannot be removed by the filter are subjected to a killing treatment. Thus, the purified seawater is filled into the ballast tank.

In order to remove aquatic organisms and the like contained in seawater, a technique of electrolyzing seawater has been developed. When a bactericide is generated by electrolysis of seawater and aquatic organisms and the like are killed by the bactericide, seawater can be purified. As described in patent documents 1 and 2, there are mainly full-scale electrolysis and side-stream electrolysis as treatment methods for a ballast water treatment machine that electrolyzes seawater to produce a bactericide. The total electrolysis method is a direct electrolysis method in which seawater filled in a ballast tank is completely electrolyzed by injecting water into the ballast tank. The side-stream electrolysis method is an indirect electrolysis method in which only a part of seawater injected into a ballast tank is electrolyzed to produce a bactericide, and the bactericide is quantitatively put into the ballast water.

The ballast water treatment apparatus described in patent document 1 includes a sea water intake line for injecting ballast water taken from the outside of a ship into a ballast water tank, and the ballast water branched from the sea water intake line is electrolyzed in an electrolysis module. When the ballast water is electrolyzed, sodium chloride and water, which are main components of the seawater, are decomposed into chlorine, sodium hydroxide and hydrogen, respectively, and the chlorine and the sodium hydroxide chemically react to generate sodium hypochlorite. The sodium hypochlorite is mixed with the ballast water delivered to the ballast water tank to purify the ballast water, and the purified ballast water is injected into the ballast water tank.

The treatment apparatus described in patent document 2 includes a line for guiding ballast water obtained from the outside of the ship to an electrolytic tank and a line for injecting water into a ballast water tank, and mixes an oxidizing agent such as sodium hypochlorite, which can be obtained using chlorine ions generated in the electrolytic tank, with the ballast water flowing into the ballast water tank.

Documents of the prior art

Patent document

Patent document 1: japanese patent publication No. 2011-528982

Patent document 2: japanese patent laid-open publication No. 2016-209876

Disclosure of Invention

Technical problem to be solved by the invention

Since chlorine cannot be generated without electrolyzing seawater, even if water outside the ship is taken as ballast water in a fresh water area such as a river, the ballast water does not contain salt and cannot be purified. Further, even if ballast water is taken from the outside of the ship in a brackish water area where fresh water and seawater are mixed, as in the estuary part, the ballast water cannot be efficiently purified because of low salt concentration. The salt concentration of the fresh water is less than 0.05 percent, the salt concentration of the seawater is more than 3.0 percent, and the salt concentration of the brackish water is 0.05 to 3.0 percent.

Therefore, when the overboard water obtained in the fresh water area or the brackish water area is used as the ballast water, in order to effectively perform the purification treatment by the electrolytic ballast treatment machine, the seawater may be taken in when the ship is underway in the seawater area and stored in advance as the seed seawater in a seed seawater tank or a part of the ballast tank.

When injecting the extra-ship water having a low salt concentration in the brackish or fresh water region as ballast water into the ballast tank, the ballast water can be purified by electrolyzing and mixing seed seawater such as a seed seawater tank into the ballast water. However, if the seed seawater is stored in this way, the amount of cargo to be loaded is reduced by at least the weight of the seed seawater, and the cargo transportation efficiency is lowered.

As another method, a large amount of salt is stored in a ship in advance, and when extra-ship water having a low salt concentration is injected into a ballast water tank, salt is put into the extra-ship water injected into an electrolysis unit, and the generated salt water is electrolyzed to generate chlorine. In order to generate chlorine in this manner, it is necessary to store a large amount of salt in a bag and mix salt with fresh water or the like to produce brine, which increases the workload and cost of passengers for the ballast water purification treatment.

The purpose of the present invention is to effectively purify overboard water obtained in a fresh water area or a brackish water area and inject the water into a ballast tank while minimizing the reduction in the load of cargo.

Means for solving the technical problem

The ballast water treatment system of the present invention comprises: a ballast water treatment machine for electrolyzing and purifying the ballast water injected into the ballast water tank; a fresh water generator for generating fresh water from seawater; a brine tank recovering and storing high concentration brine generated when fresh water is produced by the fresh water generator; a brine supply pipe for supplying the high-concentration brine in the brine tank to the ballast water treatment machine; a water intake pipe for supplying the ballast water to the ballast water treatment machine; and a pump for supplying the high-concentration brine in the brine tank to the ballast water treatment machine when the ballast water tank is filled with overboard water as ballast water.

The ballast water treatment method of the present invention comprises the steps of: electrolyzing and purifying the ballast water injected into the ballast water tank by a ballast water processor; producing fresh water from seawater by a fresh water generator; storing high-concentration brine generated when fresh water is produced by the fresh water generator in a brine tank; and supplying the high-concentration brine in the brine tank to the ballast water treatment machine when the ballast water tank is filled with overboard water as ballast water.

The ship of the present invention comprises: a hull provided with a ballast water treatment machine for electrolyzing and purifying ballast water injected into a ballast water tank; the water generator is arranged on the ship body and used for generating fresh water from seawater; a brine tank provided in the hull, recovering and storing high-concentration brine generated when fresh water is produced by the fresh water generator; a brine supply pipe provided in the hull and configured to supply the high-concentration brine in the brine tank to the ballast water treatment machine; a water intake pipe provided in the hull and configured to supply the ballast water to the ballast water treatment machine; and a pump provided in the hull and configured to supply the high-concentration brine in the brine tank to the ballast water treatment machine when the ballast water tank is filled with the overboard water as the ballast water.

Effects of the invention

High-concentration brine generated when fresh water used in a ship is produced by a fresh water generator is collected without waste and stored in a brine tank, and when overboard water in a brackish water area or a fresh water area is used as ballast water, the ballast water is purified by a bactericide obtained by electrolyzing the stored high-concentration brine, and then the ballast water tank is filled with water. Thus, the amount of high-concentration brine stored as seed seawater is reduced as compared with the case of storing seawater, and therefore, the influence on the cargo load of the ship can be minimized. Further, it is not necessary to charge salt for electrolyzing overboard water having a low salt concentration or containing no salt in a brackish water region or the like, and overboard water can be efficiently purified and filled into the ballast water tank.

Drawings

Fig. 1 is a schematic cross-sectional view showing a ship provided with a ballast water treatment system according to an embodiment.

Fig. 2 is a system configuration diagram showing the ballast water treatment system shown in fig. 1.

Fig. 3 is a block diagram showing a control circuit of the ballast water treatment system.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 shows a ship 10 such as a crude oil tanker, and a plurality of ballast tanks 11 are provided in a hull 10a of the ship 10. The draft and the draft difference between the bow and the stern are adjusted by using ballast water as a counterweight by using water taken from the outside of the ship according to the cargo load in the ship 10 as ballast water and injecting or discharging the water into or from the ballast water tank 11. In fig. 1, only three bow-side ballast water tanks 11 are shown for convenience.

A ballast water treatment machine 12 is provided in the ship 10. A water intake pipe 15 is connected between the ballast water flow inlet 13 of the ballast water treatment machine 12 and a water intake port 14 provided in the hull, and the overboard water flowing from the water intake port 14 is supplied to the ballast water treatment machine 12. A filter may be provided in the intake pipe 15 to remove foreign matter and the like in the overboard water supplied to the ballast water treatment machine 12. The ballast water treatment machine 12 can be used as follows: a full electrolysis type in which all of the brine injected into the ballast tank is electrolyzed, a side-stream electrolysis type in which only a part of the brine injected into the ballast tank is electrolyzed and quantitatively charged into the ballast water, and other methods of performing the killing treatment by electrolysis.

A fresh water generator 16 is provided in the ship 10, and a water intake pipe 19 is connected between a water intake 17 provided in the hull and a seawater inlet 18 of the fresh water generator 16. The fresh water is produced from the seawater taken from the outside of the ship by the fresh water generator 16, and is used as miscellaneous fresh water, drinking water, and boiler water. Miscellaneous fresh water is used as domestic water for washing, toilets, and the like, and boiler water is used for heating steam and for driving turbines. The fresh water generator 16 heats seawater to boil in order to produce fresh water from the seawater, and cools and collects its vapor.

The fresh water produced by the fresh water generator 16 is supplied to and stored in the tank 21 through the fresh water supply pipe 24, and is sent to a place of use through the pipe 25 as necessary.

When fresh water is produced from seawater by the fresh water generator 16, high-concentration brine having a higher salt concentration than seawater is secondarily produced. The high-concentration brine is recovered and stored in the brine tank 26 without discarding the high-concentration brine. A brine recovery pipe 31 is connected between the brine outlet 27 of the fresh water generator 16 and the brine inlet 28 of the brine tank 26 in order to supply the high concentration brine to the brine tank 26. In addition, a part of the ballast water tank 11 may be used as a brine tank instead of the brine tank 26.

As shown in fig. 2, a pump 32 is provided in the brine recovery pipe 31 to supply the high-concentration brine produced by the fresh water generator 16 to the brine tank 26. A three-way valve 33 is provided downstream of the pump 32, and when a necessary amount of high-concentration brine is stored in the brine tank 26 without planning a stop toward a salt and water area or the like, the high-concentration brine produced by the fresh water generator 16 is discharged overboard through the discharge pipe 33 a.

A bypass pipe 40 is provided between the bypass three-way valve 34 provided in the brine recovery pipe 31 and the brine recovery pipe 31 on the downstream side of the three-way valve 34, and a thickener 35 is provided in the bypass pipe 40 in order to further increase the concentration of the high-concentration brine discharged from the fresh water generator 16. A check valve 36 is provided at the bypass pipe 40 on the downstream side of the thickener 35. The check valve 36 prevents the high-concentration brine from flowing back from the brine recovery pipe 31 to the thickener 35.

As the thickener 35, a thickener having the same structure as that of the reverse osmosis type fresh water generator can be used, but as the thickener 35, an evaporation type thickener can be used as in the fresh water generator 16. In addition, as the fresh water generator 16, a reverse osmosis type fresh water generator may be used.

The high-concentration brine in the brine tank 26 is sent to the ballast water treating machine 12. A brine supply pipe 39 is connected between the brine discharge port 37 of the brine tank 26 and the brine supply port 38 of the ballast water treatment machine 12, and the high-concentration brine in the brine tank 26 is fed into the ballast water treatment machine 12 through the brine supply pipe 39. The brine supply pipe 39 is provided with a pump 41 for supplying the high-concentration brine from the brine tank 26 to the ballast water treatment apparatus 12, and a filter 42 for purifying the supplied high-concentration brine.

The ballast water processor 12 has an electrolytic unit, not shown, which electrolyzes the high-concentration brine supplied from the brine tank 26. When high-concentration brine is electrolyzed, sodium chloride and water, which are main components of the brine, are decomposed into chlorine, sodium hydroxide and hydrogen, respectively, and chlorine and sodium hydroxide chemically react to form sodium hypochlorite. Sodium hypochlorite is injected as a bactericide into a treatment flow path connected between the ballast water inflow port 13 of the ballast water treatment machine 12 and the ballast water injection port 43.

Thus, the sterilizing agent is injected into the ballast water which flows in from the water intake port 14 and is supplied to the ballast water treatment machine 12 through the water intake pipe 15, and the ballast water is purified. The purified ballast water is injected into the ballast tank 11 through a ballast water injection pipe 44 connected to the ballast water injection port 43. A predetermined amount of ballast water is supplied to each ballast tank 11. The ballast water tank 11 is provided with a discharge port, not shown, for discharging the ballast water in the ballast water tank 11 to the outside of the ship.

The flow rate adjuster 45 is provided in the brine supply pipe 39, and the injection pipe 46 connected to the intake port 14 is connected to the flow rate adjuster 45. The flow rate adjuster 45 adjusts the mixing ratio of the high-concentration brine supplied from the brine tank 26 to the ballast water treatment machine 12 and the overboard water supplied to the ballast water treatment machine 12 through the injection pipe 46. This enables adjustment of the flow rate and concentration of the high-concentration brine supplied from the brine supply pipe 39 to the ballast water treatment machine 12. Further, the outboard water may be injected into the injection pipe 46 from a water intake port different from the water intake port 14.

The water intake pipe 15 is provided with: a first flow rate sensor 47 for detecting the flow rate of the ballast water supplied to the ballast water treatment machine 12 through the intake pipe 15, a first concentration sensor 48 for detecting the concentration of the salt, and a first temperature sensor 49 for detecting the temperature. On the other hand, the brine supply pipe 39 is provided with: a second flow sensor 51 for detecting the flow rate of the high-concentration brine supplied to the ballast water treatment machine 12 through the brine supply pipe 39, a second concentration sensor 52 for detecting the concentration of the salt, and a second temperature sensor 53 for detecting the temperature.

Fig. 3 is a block diagram showing a control circuit of the ballast water treatment system. The ballast water treatment system has a controller 54, and the operation of the devices constituting the ballast water treatment system is controlled by the controller 54. The operation panel 55 is connected to the controller 54, and the start and control conditions of the ballast water treatment system are set by operating a key or the like provided on the operation panel 55. The controller 54 can also control the energization of the electrodes of the electrolysis unit provided in the ballast water treatment apparatus 12.

Detection signals from the flow rate sensors 47, 51, the concentration sensors 48, 52, and the temperature sensors 49, 53 shown in fig. 2 are sent to a controller 54 as a control means. The pump 41 and the flow rate adjuster 45 are controlled by the controller 54. The flow rate adjuster 45 adjusts the mixing ratio of the overboard water injected into the brine supply pipe 39 through the injection pipe 46 and the high concentration brine discharged from the brine tank 26, based on the flow rate of the overboard water such as the seawater or the salt fresh water supplied to the ballast water treatment machine 12 through the intake pipe 15. Thereby, the concentration and flow rate of the high-concentration brine supplied to the ballast water treatment machine 12 are controlled.

The flow rate of the high-concentration brine discharged from the brine tank 26 may be controlled by the pump 41 based on the flow rate, the salt concentration, and the temperature of the overboard water supplied to the ballast water treatment machine 12 through the intake pipe 15, and the flow rate, the salt concentration, and the temperature of the high-concentration brine supplied to the ballast water treatment machine 12 through the brine supply pipe 39.

Next, a method of treating ballast water in a ship provided with the ballast water treatment system will be described.

The ship 10 drives the fresh water generator 16 when sailing in the sea area, and fresh water is produced from the sea water. Miscellaneous fresh water, drinking water, and boiler water are produced from the fresh water produced in the production process, and are stored in tanks, respectively. The high concentration brine generated when fresh water is produced from seawater is sent to the brine tank 26 by the pump 32. The entire amount or a part of the high-concentration brine before being sent to the brine tank 26 may be sent to the thickener 35 through the bypass pipe 40, and the concentration of the high-concentration brine sent to the brine tank 26 may be further increased through the concentration step. Thus, the high-concentration brine is stored in the brine tank 26 through the storage step.

When a ship fills ballast water into the ballast tank 11 in a fresh water area or a brackish water area, the extra-ship water having a low salinity concentration in the fresh water area or the like taken in from the water intake port 14 is sent to the ballast water treatment machine 12 through the water intake pipe 15, and the high-concentration brine stored in the brine tank 26 is sent to the ballast water treatment machine 12. The transported high-concentration brine is used as seed seawater to produce a bactericide when electrolyzed by an electrolysis unit provided in the ballast water treatment machine 12. Thereby, the overboard water in the fresh water area or the salt water area is purified by the produced bactericide, and is supplied to the ballast tank 11 through the purification process.

When ballast water is purified by the full-volume electrolytic ballast water treatment apparatus 12, the extra-ship water taken in through the intake pipe 15 is mixed with high-concentration brine and supplied to the electrolytic unit. In the ballast water treatment apparatus 12 of the total electrolysis type, the mixed water in which the high-concentration brine is mixed in advance in the overboard water is supplied to the ballast water treatment apparatus 12 by connecting the brine supply pipe 39 to the intake pipe 15. In this embodiment, the high-concentration brine is supplied to the ballast water treatment machine 12 through the intake pipe 15. On the other hand, when ballast water is purified by the side-stream electrolytic ballast water treatment apparatus 12, a high-concentration brine is supplied to an electrolytic unit in the ballast water treatment apparatus 12 to generate a bactericide, and the bactericide is injected into overboard water taken in through the intake pipe 15.

The amount of high-concentration brine supplied from the brine tank 26 to the ballast water treatment machine 12 is calculated by the controller 54 based on the flow rate of ballast water before treatment, i.e., the flow rate of the saltwater region and the overboard water of the freshwater region, supplied to the ballast water treatment machine 12 through the intake pipe 15. When there is a difference between the flow rate of the high concentration brine determined by the flow rate sensor 51 and the calculation result, the controller 54 controls the pump 41 and the flow rate adjuster 45 based on the difference.

When the ballast water treatment apparatus 12 is of the full-volume electrolysis type, the temperature and salt concentration of the ballast water and the high-concentration brine supplied to the ballast water treatment apparatus 12 are detected by the temperature sensors 49 and 53 and the concentration sensors 48 and 52, and the amount of the high-concentration brine can be determined with higher accuracy by taking the detection results into consideration, so that the ballast water treatment apparatus 12 can effectively purify the overboard water in the salt-water area and the fresh-water area.

When ballast water processor 12 is of the side-stream electrolysis type, the amount of high-concentration brine can be determined with higher accuracy by taking into account the detected values of the temperature and salt concentration of the high-concentration brine supplied to ballast water processor 12. Further, by controlling the flow rate adjuster 45, the amount of the extra-ship water injected from the injection pipe 46 to the brine supply pipe 39 is adjusted to adjust the mixing ratio of the high-concentration brine and the extra-ship water injected from the injection pipe 46. This makes it possible to supply the brine having a salt concentration, which is efficiently operated by the electrolytic unit, to the ballast water treatment machine 12.

In this way, the high-concentration brine generated when the water used in the ship is produced by the fresh water generator 16 is collected and stored in the brine tank 26 without being wasted, and when the extra-ship water in the fresh water area or the salt water area is used as the ballast water, the ballast water is purified by the bactericide obtained by electrolyzing the stored high-concentration brine, and then the ballast water tank 11 is filled with the purified ballast water. Thus, when overboard water in a brackish water area or the like is used as ballast water, a smaller amount of high-concentration brine is stored and the cargo load can be increased as compared with a case where seawater is stored in advance as seed seawater in a tank.

Further, in order to make the water having a low salt concentration in the brackish water region or the like ballast water, it is not necessary to store a large amount of salt for injecting the ballast water into the electrolysis unit, and the ballast water can be efficiently purified.

When the overboard water is filled into the ballast tank 11 in the seawater area, the overboard water taken in through the intake pipe 15, that is, seawater can be supplied to the ballast water treatment machine 12 without using high-concentration brine, and the seawater can be electrolyzed by the electrolysis means to produce the bactericide. In the case of electrolyzing seawater, the high-concentration brine may be supplied to the ballast water treatment machine 12.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, instead of providing the injection pipe 46, a fixed amount of high-concentration brine may be discharged from the brine tank 26 to the ballast water treatment machine 12, and a pump may be provided in the intake pipe 15 to adjust the flow rate of the overboard water supplied to the ballast water treatment machine 12 through the intake pipe 15.

Industrial applicability

The present invention is suitable for treating ballast water for stabilizing a hull in a ship such as a crude oil tanker.