Organism adhesion suppression device and organism adhesion suppression method

Abstract

This organism adhesion suppression device and organism adhesion suppression method switch, between a first current and a second current, a DC current flowing between positive electrode members composing opposite electrodes of an organism adhesion suppression target member immersed in water and the organism adhesion suppression target member. Here, when a first current flows out of the power supply, an electrolysis reaction for consuming oxygen occurs on the surface of the organism adhesion suppression target member and the density of the DC current is less than the current density at the start of water electrolysis, and when a second current flows out of the power supply, the density of the DC current is equal to or greater than the current density at the start of water electrolysis.

Description

Biofouling control device and biofouling control method

[0001] The present disclosure relates to a biofouling control device and a method for biofouling control.

[0002] Patent Document 1 discloses a technology for preventing the attachment of marine organisms such as algae to an antifouling plate by electrolyzing seawater between an antifouling plate (cathode) covering the wall surface of a water intake channel that comes into contact with seawater and an anode made of a conductive material that comes into contact with the antifouling plate via seawater. Hydroxide ions are generated from the entire surface of the antifouling plate, creating an alkaline environment around the antifouling plate, thereby preventing the attachment of marine organisms such as algae to the antifouling plate.

[0003] Japanese Patent Application Laid-Open No. 2004-027500

[0004] According to the technology described in Patent Document 1, hydroxide ions are formed on the cathode surface. When the diffusion rate of hydroxide ions is slow, such as in a still water, low-flow environment, calcium ions, magnesium ions, and the like contained in seawater are likely to be deposited on the cathode surface as an electrodeposited film as a side reaction of the oxygen reduction reaction. As the electrodeposited film grows, unevenness occurs in the oxygen concentration distribution on the cathode surface, which can lead to the problem of biofouling in areas where the oxygen concentration is not sufficiently reduced.

[0005] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a biofouling prevention device and a biofouling prevention method that can prevent unevenness in the oxygen concentration distribution on the cathode surface and maintain the effect of preventing biofouling on the cathode surface.

[0006] The biofouling prevention device according to the present disclosure includes an anode member and a power source. The anode member constitutes a counter electrode of a target member for biofouling prevention immersed in water. The power source is electrically connected to the target member for biofouling prevention and the anode member, and is configured to be able to switch between a first current and a second current as a direct current flowing between the target member for biofouling prevention and the anode member. The second current is greater than the first current, and when the power source passes the first current, an electrolysis reaction that consumes oxygen occurs on the surface of the target member for biofouling prevention, and when the power source passes the second current, the density of the direct current is equal to or greater than the current density at the start of water electrolysis.

[0007] When the power source applies the first current, the surface may be in an oxygen-deficient state (oxygen-deficient state).

[0008] The biofouling control device may further include a controller that controls switching of the direct current between the first current and the second current.

[0009] The biofouling prevention device may further include a voltage measurement unit that measures a voltage between the target component for biofouling prevention and the anode component. The controller may determine whether the first voltage is equal to or greater than a first voltage threshold, taking the voltage when the direct current is the first current as the first voltage, and switch the direct current to the second current when it is determined that the first voltage is equal to or greater than the first voltage threshold.

[0010] The controller may determine whether the voltage when the DC current is the second current is less than a second voltage threshold value, and may switch the DC current to the first current when it is determined that the second voltage is less than the second voltage threshold value.

[0011] The biofouling prevention device may further include a charge amount measuring unit that measures the amount of charge flowing between the target member for biofouling prevention and the anode member. The controller may determine whether the amount of charge is equal to or greater than a first charge amount threshold, and when it is determined that the amount of charge is equal to or greater than the first charge amount threshold, switch the direct current to the second current.

[0012] The controller may determine whether the amount of charge is equal to or greater than a second charge threshold, and switch the direct current to the first current when it is determined that the amount of charge is equal to or greater than the second charge threshold.

[0013] The apparatus may further include a sensor that acquires status data indicating a status of the surface. The controller may determine whether or not a coating is present on the surface based on the status data, and may switch the direct current to the second current when it is determined that a coating is present on the surface.

[0014] The controller may switch the direct current to the first current if it is determined that the surface is free of a coating.

[0015] The condition data may include at least one of an image of the surface captured by a camera, the reflectivity of the surface at a predetermined light wavelength, and surface roughness data indicating the unevenness of the surface obtained by laser or ultrasonic measurement.

[0016] The biofouling control device may further include an ultrasonic generator configured to emit ultrasonic waves toward the surface.

[0017] The biofouling control device may include a changeover switch configured to allow a user to switch between a first state in which the direct current is set to a first current and a second state in which the direct current is set to a second current.

[0018] The target component for biofouling inhibition may contain at least one of austenitic stainless steel, carbon steel, and copper alloy.

[0019] The target member for biofouling inhibition may be a member that constitutes at least a part of a ship member, a marine structure member, or a water gate facility.

[0020] The biofouling prevention method according to the present disclosure relates to a biofouling prevention device including an anode member and a power source. Here, the anode member constitutes a counter electrode of a target member for biofouling prevention immersed in water. The power source is electrically connected to the target member for biofouling prevention and the anode member, and is configured to be able to switch between a first current and a second current as a direct current to be passed between the target member for biofouling prevention and the anode member. The second current is larger than the first current, and when the power source passes the first current, an electrolysis reaction that consumes oxygen occurs on the surface of the target member for biofouling prevention, and when the power source passes the second current, the density of the direct current is equal to or greater than the current density at the start of water electrolysis.

[0021] According to the present disclosure, it is possible to provide a biofouling prevention device and a biofouling prevention method that can prevent unevenness in the oxygen concentration distribution on the cathode surface and maintain the effect of preventing biofouling on the cathode surface.

[0022] Fig. 1 is a block diagram showing the configuration of a biofouling prevention device according to a first embodiment of the present disclosure. Fig. 2 is a schematic diagram showing the relationship between the potential of a biofouling prevention target member and current density. Fig. 3 is a block diagram showing the configuration of a biofouling prevention device according to a second embodiment of the present disclosure.

[0023] Hereinafter, several exemplary embodiments will be described with reference to the drawings. Note that common parts in the drawings are given the same reference numerals, and duplicated explanations will be omitted.

[0024] [Configuration of biofouling prevention device according to first embodiment] Fig. 1 is a block diagram showing the configuration of a biofouling prevention device according to an embodiment of the present disclosure. As shown in Fig. 1, the biofouling prevention device 20 includes an anode member 14 and a power supply 12. In addition, the biofouling prevention device 20 may also include a control unit 22 that controls the power supply 12.

[0025] The anode member 14 is immersed in water and disposed as a counter electrode to the target member 10 for biofouling prevention, which serves as a cathode. The anode member 14 may be disposed near the target member 10 for biofouling prevention. The anode member 14 is electrically connected to the anode side of the power source 12. The anode member 14 is composed of an insoluble anode, a soluble anode, or the like. Iridium oxide, platinum, or the like can be used as the insoluble anode. Zinc, magnesium, or the like can be used as the soluble anode. The shape of the anode member 14 is not particularly limited, but may be cylindrical, prismatic, or the like. A general galvanic anode, or the like, can be used as the anode member 14.

[0026] The biofouling-suppression target member 10 may be, for example, a ship component such as a ship propeller, or a marine structure component such as a thruster. Alternatively, the biofouling-suppression target member 10 may be a water gate facility, etc. The biofouling-suppression target member 10 is not limited to the examples given here, and various structures (or components of those structures) that are immersed in water can be targets for biofouling suppression.

[0027] The target member 10 for biofouling inhibition is electrically connected to the cathode side of a power source 12. Specifically, the target member 10 for biofouling inhibition may be made of at least one of austenitic stainless steel, carbon steel, and a copper alloy. The copper alloy is not particularly limited, but may be, for example, aluminum bronze, manganese brass, or the like.

[0028] The power supply 12 is electrically connected to the target member 10 for biofouling prevention and the anode member 14 via an electric cable or the like. The power supply 12 has a function of passing a direct current between the target member 10 for biofouling prevention and the anode member 14. The power supply 12 can be an external power supply such as a general potentiogalvanostat.

[0029] The power source 12 is configured to be able to switch between a first current and a second current as the direct current to be passed between the biofouling prevention target member 10 and the anode member 14. The first current and the second current will be described in detail later.

[0030] The biofouling control device 20 may also include a changeover switch (not shown) configured to be switchable by a user, where the changeover switch switches between a first state in which the DC current from the power source 12 is set to a first current, and a second state in which the DC current is set to a second current.

[0031] The control unit 22 (controller) has a function of controlling the power source 12 to control the flow of electricity between the biofouling prevention target member 10 and the anode member 14. In particular, the control unit 22 may be configured to switch the direct current from the power source 12 between a first current and a second current.

[0032] The control unit 22 is electrically connected to the power source 12 via an electric cable or the like. The control unit 22 can control the start and stop of current flow and the current density of the direct current flowing between the target member 10 for biofouling prevention and the anode member 14. The control unit 22 can be configured, for example, by a general computer or the like. The control unit 22 may be configured integrally with the power source 12.

[0033] For example, by controlling the power supply 12 to increase the current density of the direct current passing between the target material 10 for biofouling prevention and the anode member 14, the nature of the chemical reaction near the surface of the target material 10 for biofouling prevention changes.

[0034] 2 is a schematic diagram showing the relationship between the potential of the target component 10 and current density, with the horizontal axis representing current density and the vertical axis representing the potential of the target component 10, and the solid line representing the potential of the target component 10 relative to the current density.

[0035] When a direct current is applied between the target member 10 for biofouling prevention and the anode member 14 in a state where the water contains a large amount of oxygen, a chemical reaction shown in Chemical Formula 1 occurs near the surface of the target member 10 for biofouling prevention. Due to the chemical reaction shown in Chemical Formula 1, oxygen around the target member 10 for biofouling prevention is reduced to hydroxide ions (OH － ) is produced, consuming the oxygen contained in the water.

[0036]

[0037] As a result, the oxygen concentration around the target member 10 for biofouling prevention decreases, forming a low-oxygen region 16. In such an oxygen reduction region A, the potential of the target member 10 for biofouling prevention increases gradually as the current density increases.

[0038] In a state where all the oxygen around the biofouling prevention target member 10 has been consumed, when a direct current is passed between the biofouling prevention target member 10 and the anode member 14, a chemical reaction shown in Chemical Formula 2 occurs near the surface of the biofouling prevention target member 10. Due to the chemical reaction shown in Chemical Formula 2, the water around the biofouling prevention target member 10 is electrolyzed to produce hydroxide ions (OH － ) and hydrogen (H ２ ) is generated.

[0039]

[0040] In such a water electrolysis region B, the potential of the target member 10 for biofouling prevention remains substantially constant with increasing current density.

[0041] Between the oxygen reduction zone A and the water electrolysis zone B, a transition zone C is formed near the surface of the biofouling-suppression target 10, where the chemical reaction shown in Chemical Formula 1 transitions to the chemical reaction shown in Chemical Formula 2. In the transition zone C, the potential of the biofouling-suppression target 10 rises sharply with increasing current density.

[0042] By passing a direct current between the biofouling-suppression target member 10 and the anode member 14, oxygen (such as dissolved oxygen in water) around the biofouling-suppression target member 10 is consumed by reduction, and a low-oxygen region is formed around the biofouling-suppression target member 10. This reduces the oxygen concentration around the biofouling-suppression target member 10, thereby suppressing the biological activity of organisms such as barnacles and inhibiting the attachment of organisms to the biofouling-suppression target member 10.

[0043] When the power source 12 applies a first current to the target component 10 to inhibit adhesion of organisms to the target component 10, the first current is set so that an electrolysis reaction that consumes oxygen occurs on the surface of the target component 10. For example, the first current is set so that a current density corresponding to the oxygen reduction region A or the transition region C is achieved. When the power source 12 applies the first current, the surface of the target component 10 to inhibit adhesion of organisms to the target component 10 may be in an oxygen-deficient state. An oxygen-deficient state includes an oxygen-deficient state, and refers to, for example, a state in which the amount of dissolved oxygen in water is lower than normal.

[0044] When direct current is applied between the target member 10 for biofouling prevention and the anode member 14 in seawater, calcium (Ca) and magnesium (Mg) contained in seawater cause CaCO 3 to form on the surface of the target member 10 for biofouling prevention. ３ and Mg(OH) ２ When electricity is applied in seawater in this way, a coating and a low-oxygen region 16 are formed around the target member 10 for biofouling prevention.

[0045] Furthermore, if a coating is formed on the surface of the biofouling prevention target member 10, the coating can be peeled off and removed by applying a DC current set to a second current greater than the first current from the power source 12. In particular, the second current is set so as to achieve a current density corresponding to the water electrolysis region B.

[0046] This allows the coating to be pushed up and peeled off by the hydrogen gas generated on the surface of the target member 10. In addition, hydroxide ions accumulate on the surface of the target member 10, increasing the pH, which promotes peeling off of the coating.

[0047] In addition, the control unit 22 may be equipped with a memory that stores information such as the material of the biofouling suppression target member 10, the current density at the start of water electrolysis, the current density at the boundary between the oxygen reduction region A and the transition region C, and the current density at the boundary between the water electrolysis region B and the transition region C.

[0048] [Configuration of a biofouling prevention device according to a second embodiment] Figure 3 is a block diagram showing the configuration of a biofouling prevention device according to a second embodiment of the present disclosure. In addition to the components shown in Figure 1, the biofouling prevention device 20 may further include a voltage measurement unit DT1, an electric charge measurement unit DT2, a sensor CM, and an ultrasonic oscillator SV.

[0049] The voltage measurement unit DT1 measures the voltage between the biofouling prevention target member 10 and the anode member 14. Data on the measured voltage is sent to the control unit 22.

[0050] The charge amount measuring unit DT2 measures the amount of charge that has flowed between the biofouling prevention target member 10 and the anode member 14. For example, the charge amount measuring unit DT2 may measure the amount of charge by integrating over time the current that has flowed between the biofouling prevention target member 10 and the anode member 14. Data on the measured amount of charge is transmitted to the control unit 22.

[0051] The sensor CM acquires status data indicating the status of the surface of the biofouling prevention target member 10. The status data is transmitted to the control unit 22. For example, the sensor CM may be a camera that captures an image of the surface of the biofouling prevention target member 10, or a reflection measurement device that measures the reflectance of the surface of the biofouling prevention target member 10 at a predetermined light wavelength. Alternatively, the sensor CM may be a measurement device that acquires surface roughness data indicating the unevenness of the surface of the biofouling prevention target member 10 by laser or ultrasonic measurement.

[0052] Therefore, the condition data may include at least one of an image captured by a camera, the reflectivity of the surface at a specified light wavelength, and surface roughness data indicating the unevenness of the surface obtained by laser or ultrasonic measurement.

[0053] The ultrasonic oscillator SV is configured to be able to irradiate ultrasonic waves toward the surface of the biofouling prevention target member 10. The ultrasonic oscillator SV may be operated continuously, or may be operated at a predetermined timing based on a drive signal from the control unit 22. This allows the coating formed on the surface of the biofouling prevention target member 10 to be removed by ultrasonic vibration.

[0054] The control unit 22 controls the power supply 12 based on the measured voltage data, the measured charge amount data, and the status data.

[0055] For example, the control unit 22 may acquire the voltage when the DC current is the first current as the first voltage and determine whether the first voltage is equal to or greater than a first voltage threshold. If it is determined that the first voltage is equal to or greater than the first voltage threshold, the control unit 22 may switch the DC current to the second current. When a coating is formed on the surface of the biofouling prevention target member 10, the voltage between the biofouling prevention target member 10 and the anode member 14 increases. Therefore, if the first voltage is equal to or greater than the first voltage threshold, a process for removing the coating formed on the surface can be initiated.

[0056] The control unit 22 may also acquire the voltage when the DC current is the second current as the second voltage and determine whether the second voltage is less than a second voltage threshold. If it is determined that the second voltage is less than the second voltage threshold, the control unit 22 may switch the DC current to the first current. When the coating formed on the surface of the biofouling prevention target member 10 is removed, the voltage between the biofouling prevention target member 10 and the anode member 14 drops. Therefore, if the second voltage is less than the second voltage threshold, the process of removing the coating formed on the surface can be terminated.

[0057] The second voltage threshold may be smaller than the first voltage threshold, which allows the thickness of the coating at the end of the coating removal process to be smaller than the thickness of the coating at the start of the coating removal process, thereby ensuring reliable removal of the coating.

[0058] The control unit 22 may also determine whether the measured charge amount is equal to or greater than a first charge amount threshold. If it is determined that the charge amount is equal to or greater than the first charge amount threshold, the control unit 22 may switch the DC current to a second current. The thickness or total amount of the coating formed on the surface of the biofouling prevention target member 10 tends to be proportional to the amount of charge flowing between the biofouling prevention target member 10 and the anode member 14. Therefore, it is useful to start the process of removing the coating based on the amount of charge. This allows the period required for coating removal to be limited, thereby reducing power consumption by the biofouling prevention device 20.

[0059] Furthermore, the control unit 22 may determine whether the measured charge amount is equal to or greater than a second charge amount threshold. If it is determined that the charge amount is equal to or greater than the second charge amount threshold, the control unit 22 may switch the DC current to the first current. The amount of hydrogen generated by electrolysis on the surface of the biofouling prevention target member 10 tends to be proportional to the amount of charge flowing between the biofouling prevention target member 10 and the anode member 14. It is useful to terminate the coating removal process based on the amount of charge. This allows the period required for coating removal to be limited, thereby reducing power consumption by the biofouling prevention device 20.

[0060] The control unit 22 may also determine whether or not there is a coating on the surface of the target member 10 for biofouling prevention, based on the status data.

[0061] For example, if the condition data is an image captured by a camera of the surface of the biofouling prevention target member 10, image recognition may be performed based on the captured image to detect changes in the condition of the surface of the biofouling prevention target member 10. If the amount of change exceeds a predetermined threshold, it may be determined that a coating is present on the surface of the biofouling prevention target member 10.

[0062] If the status data is the reflectance of the surface at a specified light wavelength, it may be determined whether the reflectance has changed to a value outside a specified range, and if the reflectance has changed to a value outside the specified range, it may be determined that a coating is present on the surface of the biofouling prevention target member 10.

[0063] If the condition data is surface roughness data indicating the unevenness of the surface of the target component 10 for biofouling prevention, it may be determined that a coating is present on the surface of the target component 10 for biofouling prevention if the surface roughness exceeds a predetermined threshold value.

[0064] The control unit 22 may switch the direct current to the second current when it is determined that a coating is present on the surface of the biofouling prevention target member 10. On the other hand, when it is determined that a coating is not present on the surface of the biofouling prevention target member 10, the control unit 22 may switch the direct current to the first current.

[0065] Effect of the embodiment As described in detail above, the biofouling prevention device according to the present disclosure includes an anode member and a power source. Here, the anode member constitutes a counter electrode of a biofouling prevention target member immersed in water. The power source is electrically connected to the biofouling prevention target member and the anode member, and is configured to be able to switch between a first current and a second current as a direct current to be passed between the biofouling prevention target member and the anode member. The second current is larger than the first current, and when the power source passes the first current, an electrolysis reaction that consumes oxygen occurs on the surface of the biofouling prevention target member, and when the power source passes the second current, the density of the direct current is equal to or greater than the current density at the start of water electrolysis.

[0066] This prevents unevenness in the oxygen concentration distribution on the cathode surface, making it possible to maintain the biofouling prevention effect on the cathode surface. In particular, since the coating formed on the surface of the biofouling prevention target member 10, which is the cathode, can be reliably removed, the occurrence of unevenness in the oxygen concentration distribution due to the influence of the coating adhered to the surface is prevented. As a result, the biofouling prevention effect can be maintained.

[0067] In the present disclosure, when the power source applies the first current, the surface may be in an oxygen-deficient state (oxygen-deficient state), thereby suppressing the biological activity of organisms such as barnacles and inhibiting the attachment of organisms to the biofouling-suppression target member 10.

[0068] Furthermore, the biofouling prevention device according to the present disclosure may further include a controller that controls switching of the direct current between the first current and the second current, thereby enabling automatic removal of the coating formed on the surface of the biofouling prevention target member 10.

[0069] The biofouling prevention device according to the present disclosure may further include a voltage measurement unit that measures the voltage between the target member for biofouling prevention and the anode member. The controller may determine whether the voltage when the direct current is the first current as a first voltage, whether the first voltage is equal to or greater than a first voltage threshold, and switch the direct current to a second current if it is determined that the first voltage is equal to or greater than the first voltage threshold. When a coating is formed on the surface of the target member for biofouling prevention 10, the voltage between the target member for biofouling prevention 10 and the anode member 14 increases. Therefore, when a coating is formed, a process for removing the coating formed on the surface can be reliably initiated.

[0070] Furthermore, in the present disclosure, the controller may determine whether the voltage when the DC current is the second current is less than a second voltage threshold value, using the second voltage as the voltage. If it is determined that the second voltage is less than the second voltage threshold value, the controller may switch the DC current to the first current. When the coating formed on the surface of the biofouling prevention target member 10 is removed, the voltage between the biofouling prevention target member 10 and the anode member 14 drops. Therefore, when the coating is removed, the process of removing the coating formed on the surface can be reliably completed.

[0071] Furthermore, the biofouling prevention device according to the present disclosure may further include a charge amount measuring unit that measures the amount of charge flowing between the biofouling prevention target member and the anode member. The controller may determine whether the amount of charge is equal to or greater than a first charge amount threshold, and switch the direct current to the second current when it is determined that the amount of charge is equal to or greater than the first charge amount threshold.

[0072] The thickness or total amount of the coating formed on the surface of the biofouling prevention target member 10 tends to be proportional to the amount of charge flowing between the biofouling prevention target member 10 and the anode member 14. Therefore, it is useful to start the process of removing the coating based on the amount of charge. This makes it possible to limit the period required for coating removal, thereby reducing power consumption by the biofouling prevention device 20.

[0073] In addition, in the present disclosure, the controller may determine whether the amount of charge is equal to or greater than a second charge threshold, and switch the direct current to the first current if it is determined that the amount of charge is equal to or greater than the second charge threshold.

[0074] The amount of hydrogen generated by electrolysis on the surface of the biofouling prevention target component 10 tends to be proportional to the amount of charge flowing between the biofouling prevention target component 10 and the anode component 14. It is useful to terminate the coating removal process based on the amount of charge. This allows the time required for coating removal to be limited, thereby reducing power consumption by the biofouling prevention device 20.

[0075] Furthermore, the biofouling control device according to the present disclosure may further include a sensor that acquires status data indicating the condition of the surface. The controller may determine whether or not a coating is present on the surface based on the status data, and if it is determined that a coating is present on the surface, switch the DC current to the second current. This allows a process to be initiated to remove the coating when it is present, and the period during which the process is required to be performed can be limited. As a result, power consumption by the biofouling control device 20 can be reduced.

[0076] In the present disclosure, the controller may switch the DC current to the first current when it is determined that no coating is present on the surface. This allows the coating removal process to be terminated when the coating is removed, thereby limiting the period during which the process is required. As a result, power consumption by the biofouling control device 20 can be reduced.

[0077] Furthermore, in the present disclosure, the condition data may include at least one of an image of the surface captured by a camera, the reflectance of the surface at a predetermined light wavelength, and surface roughness data indicating the surface irregularities obtained by laser or ultrasonic measurement. This allows the coating removal process to be performed based on data obtained by actually observing the surface condition of the biofouling prevention target member 10. As a result, the coating formed on the surface of the biofouling prevention target member 10 can be removed more reliably.

[0078] The biofouling prevention device according to the present disclosure may further include an ultrasonic oscillator configured to irradiate ultrasonic waves toward the surface, thereby enabling the coating formed on the surface of the biofouling prevention target member 10 to be removed by ultrasonic vibrations.

[0079] Furthermore, the biofouling prevention device according to the present disclosure may include a selector switch configured to allow a user to switch between a first state in which the direct current is set to a first current and a second state in which the direct current is set to a second current, thereby enabling the process of removing the coating formed on the surface of the biofouling prevention target member 10 to be performed at a timing determined by the user.

[0080] In addition, in the present disclosure, the target component for biofouling inhibition may contain at least one of austenitic stainless steel, carbon steel, and copper alloy, thereby further improving the biofouling inhibition effect.

[0081] Furthermore, in the present disclosure, the target member for biofouling inhibition may constitute at least a part of a ship member, a marine structure member, or a water gate equipment, thereby making it possible to inhibit biofouling in the ship member, the marine structure member, or the water gate equipment, thereby improving durability and extending the lifespan.

[0082] The biofouling prevention method according to the present disclosure relates to a biofouling prevention device including an anode member and a power source. Here, the anode member constitutes a counter electrode of a target member for biofouling prevention immersed in water. The power source is electrically connected to the target member for biofouling prevention and the anode member, and is configured to be able to switch between a first current and a second current as a direct current to be passed between the target member for biofouling prevention and the anode member. The second current is larger than the first current, and when the power source passes the first current, an electrolysis reaction that consumes oxygen occurs on the surface of the target member for biofouling prevention, and when the power source passes the second current, the density of the direct current is equal to or greater than the current density at the start of water electrolysis.

[0083] This prevents unevenness in the oxygen concentration distribution on the cathode surface, making it possible to maintain the biofouling prevention effect on the cathode surface. In particular, since the coating formed on the surface of the biofouling prevention target member 10, which is the cathode, can be reliably removed, the occurrence of unevenness in the oxygen concentration distribution due to the influence of the coating adhered to the surface is prevented. As a result, the biofouling prevention effect can be maintained.

[0084] Each of the functions described in the above embodiments may be implemented by one or more processing circuits, including programmed processors, electrical circuits, and even devices such as application specific integrated circuits (ASICs), or circuit components arranged to perform the described functions.

[0085] According to the present disclosure, for example, by using infrastructure facilities such as floodgate facilities as cathodes and maintaining the effect of preventing biofouling on the cathode surface, it is possible to improve the durability and extend the lifespan of the infrastructure facilities. Therefore, it is possible to contribute to, for example, Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation."

[0086] Although several embodiments have been described, the embodiments can be modified or varied based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined, unless they contradict each other.

[0087] The entire contents of Japanese Patent Application No. 2023-120022 (filing date: July 24, 2023) are incorporated herein by reference.

[0088] REFERENCE SIGNS LIST 10 Biofouling prevention target member 12 Power supply 14 Anode member 20 Biofouling prevention device 22 Control unit CM Sensor DT1 Voltage measurement unit DT2 Charge amount measurement unit SV Ultrasonic oscillator

Claims

1. A biofouling inhibition device comprising: an anode member that constitutes a counter electrode of a biofouling inhibition target material immersed in water; and a power source electrically connected to the biofouling inhibition target material and the anode member, and configured to be able to switch a direct current flowing between the biofouling inhibition target material and the anode member between a first current and a second current, wherein the second current is greater than the first current, when the power source flows the first current, an electrolysis reaction that consumes oxygen occurs on the surface of the biofouling inhibition target material, and when the power source flows the second current, the density of the direct current is equal to or greater than the current density at the start of electrolysis of water.

2. The biofouling control device of claim 1, wherein the surface is oxygen-deprived when the power source passes the first current.

3. The biofouling control device according to claim 1, further comprising a controller that controls switching of the direct current between the first current and the second current.

4. A biofouling prevention device as described in claim 3, further comprising a voltage measuring unit that measures the voltage between the biofouling prevention target member and the anode member, wherein the controller determines whether the first voltage is equal to or greater than a first voltage threshold value, assuming that the voltage when the direct current is the first current as a first voltage, and switches the direct current to the second current when it is determined that the first voltage is equal to or greater than the first voltage threshold value.

5. The biofouling suppression device described in claim 4, wherein the controller determines whether the second voltage is less than a second voltage threshold value, using the voltage when the DC current is the second current as a second voltage, and switches the DC current to the first current when it is determined that the second voltage is less than the second voltage threshold value.

6. A biofouling prevention device as described in claim 3, further comprising an electric charge measuring unit that measures the amount of electric charge flowing between the biofouling prevention target member and the anode member, wherein the controller determines whether the amount of electric charge is equal to or greater than a first electric charge threshold, and switches the direct current to the second current when it is determined that the amount of electric charge is equal to or greater than the first electric charge threshold.

7. The biofouling prevention device described in claim 6, wherein the controller determines whether the amount of charge is equal to or greater than a second charge threshold, and switches the direct current to the first current when it is determined that the amount of charge is equal to or greater than the second charge threshold.

8. A biofouling prevention device as described in claim 3, further comprising a sensor that acquires status data indicating the status of the surface, wherein the controller determines whether or not a coating is present on the surface based on the status data, and switches the direct current to the second current when it is determined that a coating is present on the surface.

9. The biofouling prevention device according to claim 8, wherein the controller switches the direct current to the first current when it is determined that no coating is present on the surface.

10. A biofouling prevention device as described in claim 8, wherein the condition data includes at least one of an image of the surface captured by a camera, the reflectance of the surface at a specified light wavelength, and surface roughness data indicating the unevenness of the surface obtained by laser or ultrasonic measurement.

11. The biofouling control device of claim 1, further comprising an ultrasonic generator configured to irradiate ultrasonic waves toward the surface.

12. A biofouling prevention device as described in any one of claims 1 to 11, comprising a changeover switch configured to allow a user to switch between a first state in which the direct current is set to the first current, and a second state in which the direct current is set to the second current.

13. A biofouling prevention device according to any one of claims 1 to 11, wherein the biofouling prevention target component includes at least one of austenitic stainless steel, carbon steel, and copper alloy.

14. A biofouling prevention device as described in any one of claims 1 to 11, wherein the biofouling prevention target member constitutes at least part of a ship member, a marine structure member, or a water gate facility.

15. A method for inhibiting biofouling involving a biofouling inhibition device comprising: an anode member constituting a counter electrode of a biofouling inhibition target member immersed in water; and a power source electrically connected to the biofouling inhibition target member and the anode member and configured to be able to switch a direct current flowing between the biofouling inhibition target member and the anode member between a first current and a second current, wherein the second current is greater than the first current, an electrolysis reaction that consumes oxygen occurs on the surface of the biofouling inhibition target member when the power source flows the first current, and a density of the direct current is greater than or equal to the current density at the start of electrolysis of water when the power source flows the second current.

Images