JP2004002984A - Antifouling and corrosion prevention apparatus for metal entity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply an antifouling and corrosion prevention treatment to a metal entity without applying a coating thereto. <P>SOLUTION: A bar screen 6 provided on a water intake lateral of LNG (Liquefied Natural Gas), a power station or the like, e.g., consists of carbon steel or alloy steel (such as stainless steel). An anode electrode 12 is connected to the plus terminal of a DC power system 10, and the bar screen 6 is connected to the minus terminal via a potential controller 11. Thus, the vicinity of the surface of the bar screen 6 is made into an alkaline atmosphere, and evasion effect of marine organisms is caused. As a result, antifouling of the bar screen 6 is carried out without applying an antifouling coating material to the bar screen 6. Further, a reference electrode 13 is connected to the potential controller 11, and the potential controller 11 retains the electric potential of the bar screen 6 to the one capable of corrosion prevention based on the electric potential detected by the referential electrode 13. Thus, the bar screen 6 is subjected to cathode protection, and the corrosion protection is carried out without applying an anticorrosive coating material thereto. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to an apparatus for preventing and contaminating a metal object placed in seawater, and particularly to an apparatus for preventing and contaminating a metal object by applying a current to the metal object.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, marine organisms are prevented from adhering to metal objects installed in seawater (for example, metal structures such as bar screens and rotary screens installed in intake channels of LNG plant facilities and power plants) (ie, antifouling). For this purpose, a method of applying an antifouling paint to a metal structure has been widely used (for example, see Patent Document 1). However, since the effect was not sufficiently exhibited, it was necessary to periodically stop plants such as LNG plant facilities and power plants and perform cleaning work to remove attached marine organisms.
[0003]
[Patent Document 1]
JP-A-59-15813
A method has also been used in which a conductive film or a noble metal-based material is used as an anode and a direct current is applied to the anode. This antifouling method utilizes the fact that when an electric current is applied to a conductive coating film or a noble metal-based metal object, seawater is electrolyzed, and the seawater near the anode surface becomes an acidic atmosphere, which produces an effect of repelling marine organisms. .
However, when the antifouling metal material was used as the anode, the metal was dissolved in seawater and corroded (or rusted). Therefore, in order to prevent corrosion (that is, to prevent corrosion), an insulating paint is applied to the metal surface, and a conductive paint (for example, a carbon-based conductive material) is further applied thereon. It was antifouling.
[0005]
[Problems to be solved by the invention]
However, application of an insulating paint (and a conductive paint) may be difficult due to its structure depending on a metal object. For example, a metal object having a complicated structure such as a bar screen having a lattice structure has a problem that an unpainted portion is generated and corroded therefrom.
[0006]
The present invention has been made in view of such a situation, and an object of the present invention is to prevent stain and corrosion without painting a metal object.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an antifouling and anticorrosion device according to the present invention uses a metal object to be subjected to antifouling and anticorrosion placed in seawater as a cathode, maintains the anticorrosion potential, and is placed in seawater. By applying a current to the metal object from the anode electrode, the metal object is stain- and corrosion-proof.
[0008]
That is, the antifouling and anticorrosion device according to the present invention is a device for antifouling and anticorrosion of a metal object placed in seawater, which is placed in seawater and has a known potential in seawater depending on the substance used. A reference electrode, an anode electrode placed in seawater, the metal object, the reference electrode, connected to the anode electrode, the anode electrode at a relatively high potential, the metal object at a relatively low potential. Power supply means for setting the potential of the metal object to corrosion prevention based on the potential of the reference electrode.
[0009]
According to the present invention, a metal object placed in seawater is set to a negative potential with respect to the anode terminal, so that the vicinity of the surface of the metal object has an alkaline atmosphere. As a result, a repelling effect of marine organisms is generated, and metal objects are stained. In addition, since current flows from the anode terminal to the metal object, the metal object is cathodic protected. Therefore, antifouling and anticorrosion of a metal object can be performed without applying an antifouling paint or an anticorrosion paint to the metal object.
[0010]
Preferably, the power supply means sets the metal object to a potential at which corrosion can be prevented and organisms in seawater do not adhere to the metal object, or a potential at which a compound in seawater does not adhere to the metal object. I do. As a result, organisms in the seawater can be repelled, or a compound (for example, calcium carbonate, magnesium hydroxide, or the like) in the seawater can be prevented from adhering / growing to the metal object and blocking the mesh or the like.
[0011]
More preferably, the anode electrode and the metal object are arranged at such a distance that the density of current flowing from the anode electrode to the metal object is substantially constant at each location of the metal object. Further, the reference electrode is arranged near the metal object.
[0012]
In one embodiment of the present invention, the power supply means includes a potential control device and a DC power supply device, wherein the DC power supply device has the anode terminal connected to the anode electrode, and the cathode terminal connected to the potential terminal. A control device is connected, the potential control device is connected to the reference electrode at one terminal, the metal object is connected to the other terminal, and detects the potential of the reference electrode, the detected potential to The metal object is set to the anticorrosive potential based on the above. Although the system based on the potential control of the metal object has been described, in the steady state, the potential and the current amount have a correlation, and the current amount control can be performed instead of the potential control.
[0013]
The reference electrode is made of silver / silver chloride (for example, silver chloride adhered to the surface of silver) or zinc.
[0014]
The anode electrode may be formed of a noble metal-based electrode, a titanium substrate carrying a noble metal-based electrode, or a conductive coating applied to the inner wall surface of a water channel provided with the metal object and guiding seawater. A membrane can also be used. In the latter case, the conductive coating is separated into two mutually insulated first and second parts, and the power supply means comprises an electric power supply for the first and second parts. Polarity switching means for switching the polarity of the first part and the second part at predetermined time intervals, and the polarity switching means switches the polarity of the first part and the second part. Of these, at least a portion having the polarity of the anode may be configured to supply a current to the metal object.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described using an example of an antifouling and anticorrosion (hereinafter, referred to as “antifouling / anticorrosion”) apparatus for a bar screen provided in an intake channel of a power plant.
[0016]
<First embodiment>
FIG. 1 is a block diagram illustrating a schematic configuration of the power plant 100. FIG. 2 is a block diagram showing the configuration of the antifouling / corrosion preventing apparatus 1 according to the first embodiment of the present invention for preventing and contaminating a part of the intake channel 5 of the power plant 100 and the bar screen 6. .
[0017]
The power plant 100 is provided with an intake channel 5 for taking in seawater. A curtain wall 8 is provided near the water intake 5 a of the water intake channel 5. A bar screen 6, a rotary screen 9, and a circulating water pump 7 are provided inside the water intake channel 5 toward the downstream side of the water intake flow A.
[0018]
The bar screen 6 and the rotary screen 9 mainly block dust contained in the seawater and prevent the dust from entering the circulating water pump 7. For example, the bar screen 6 is made of steel (carbon steel, alloy steel (stainless steel or the like), cast iron or the like), and has an outer diameter of H = 10 m and W = 5 m as shown in the schematic perspective view of FIG. A lattice shape having a rectangular parallelepiped shape having a thickness (depth) D = 0.2 to 0.3 m, and a plurality of through holes 60 having a length of about 0.3 m and a width of about 0.1 m formed on both front and back surfaces thereof. Having. This lattice shape blocks trash in seawater.
[0019]
The circulating water pump 7 pumps seawater and sends the pumped seawater to the condenser 5c of the turbine / power generation room 50 via the circulating water pipe 5b. After being used for power generation, the fed seawater is returned to the ocean via the circulating water pipe 5d and the outlet 5e.
[0020]
The antifouling and anticorrosion device 1 is for antifouling and anticorrosion of the bar screen 6, and includes a DC power supply device 10, a potential control device (voltage control device) 11, an anode electrode 12, and a reference electrode 13. The power supply device 10 and the potential control device 11 may be provided outside the intake channel 5 or may be provided in the intake channel 5 in a waterproof state. Further, a current control device can be used instead of the potential control device 11.
[0021]
The anode terminal (+) of the DC power supply 10 is connected to the anode electrode 12 via a lead L1, and the cathode terminal (-) is connected to the potential controller 11 via a lead L2. One terminal of the potential control device 11 is connected to the reference electrode 13, and the other terminal is connected to the bar screen 6.
[0022]
The anode electrode 12 can be made of an insoluble material (for example, carbon, platinum, gold, or the like), or can be made of another conductive material (for example, iron, magnetite, or the like). If the anode electrode 11 is made of a metal that dissolves in seawater, such as iron, the thickness of the anode electrode 11 is reduced by corrosion, so that the anode electrode 11 is periodically replaced.
[0023]
The anode electrode 12 is separated from the bar screen 6 by a predetermined distance so that the current density of the current flowing from the anode electrode 12 into the bar screen 6 via seawater is substantially constant at each point on the surface of the bar screen 6. (E.g., at a distance of several meters to several tens of meters). In addition, it is preferable that the anode electrode 12 be fixed to the wall surface 51 in order to prevent the anode electrode 12 from flowing by the intake water flow A.
[0024]
The reference electrode 13 is provided to detect a potential serving as a reference for setting the potential of the bar screen 6 to a potential capable of preventing corrosion (hereinafter referred to as “corrosion prevention potential”). The reference electrode 13 is made of, for example, silver (Ag) / silver chloride (AgCl), zinc (Zn), or the like. When the reference electrode 13 is corroded by seawater and loses its thickness, it is replaced with a new one.
[0025]
The reference electrode 13 is attached to the wall surface 51 of the water intake channel 5 while being separated from the bar screen 6 (that is, with seawater interposed between the bar screen 6 and the reference electrode 13) so as not to short-circuit with the bar screen 6. Alternatively, an insulating member may be attached to the bar screen 6 and attached to the bar screen 6 with the insulating member interposed therebetween. However, in order to reduce the influence of seawater resistance (electrical resistance), it is preferable that the reference electrode 13 is disposed near the bar screen 6 (for example, at a distance of about 1 mm to several mm). When the reference electrode 13 is not disposed near the bar screen 6, the potential of the bar screen 6 controlled by the potential control device 11 described later is set to a value corrected in consideration of seawater resistance.
[0026]
The DC power supply 10 generates a voltage so as to keep the bar screen 6 (cathode terminal) at a negative potential with respect to the anode electrode 11 (anode terminal), and supplies a current. That is, the anode electrode 11 is maintained at a relatively high potential, and the bar screen 6 is maintained at a relatively low potential.
[0027]
The current of the DC power supply 10 is preferably such that the current density flowing into the bar screen 6 is 0.05 to 0.3 A / m ² (average current density). Therefore, the voltage of the DC power supply 10 (that is, the potential difference between the anode electrode 11 and the bar screen 6) Vout is a value that achieves this current density in consideration of seawater resistance.
[0028]
The potential control device 11 maintains the potential of the bar screen 6 (that is, the potential of the cathode terminal) at the anticorrosion potential based on the potential of the reference electrode 13 (hereinafter, referred to as “reference potential”). That is, since the reference electrode 13 has a known potential specific to the substance in the seawater depending on the substance used therein, the potential control device 11 determines the anticorrosion potential of the bar screen 6 by detecting the reference potential. And the determined anticorrosion potential can be stably maintained.
[0029]
The potential control device 11 includes, for example, a detector that detects (or measures and monitors) the potential of the reference electrode 13, a variable resistor, and a control unit that controls the resistance value of the variable resistor. It is composed of a equipped sequencer. Then, the control unit of the sequencer changes the resistance value of the variable resistor based on the potential of the reference electrode 13 detected (detected and monitored) by the detector and adjusts the amount of current, thereby controlling the bar screen 6. Adjust the potential to the anticorrosion potential.
[0030]
The anticorrosion potential differs depending on the type of the material constituting the bar screen. For example, when the bar screen 6 is made of steel (carbon steel) and silver / silver chloride is used as the reference electrode 13, the anticorrosion potential is -770 [mV] with respect to the reference potential (almost 0 mV). ] Is as follows. However, if the potential of the bar screen 6 becomes too low, compounds (metal salts) in sea water such as calcium carbonate (CaCO ₃ ) and magnesium hydroxide (Mg (OH) ₂ ) adhere to the surface of the bar screen 6, There is a possibility that the through-holes 60 will be closed soon after the deposition and growth. Therefore, the potential of the bar screen 6 is preferably higher than the potential at which the adhesion does not proceed. The potential at which this adhesion does not proceed is -1400 mV or more with respect to the reference potential.
[0031]
Therefore, the potential of the bar screen 6 is preferably -1400 mV or more and -770 mV or less with respect to the reference potential.
[0032]
That is, the potential control device 11 detects the reference potential, and maintains the potential of the bar screen 6 (referred to as Vbar) at a potential in the range of −1400 mV to −770 mV with respect to the detected reference potential. As a result, the potential of the anode electrode 12 (Vpos) is Vpos = Vbar + Vout (Vout is a voltage generated by the DC power supply).
[0033]
Further, when the bar screen 6 is made of steel (carbon steel), when zinc is used as the reference electrode 11, the reference potential becomes 1050 mV lower than when silver chloride is used. Is preferably −350 mV or more and +280 mV or less with respect to the reference potential.
[0034]
When the bar screen 6 is made of stainless steel and silver chloride is used as the reference electrode 13, the anticorrosion potential is -600 [mV] or less with respect to the reference potential. On the other hand, the potential at which calcium carbonate, magnesium hydroxide and the like do not deposit and grow is -1400 mV or more as described above. Therefore, the potential of the stainless steel bar screen 6 is preferably -1400 mV to -600 mV with respect to the reference potential.
[0035]
When zinc is used as the reference electrode 13 in a case where the bar screen 6 is made of stainless steel, the potential of the bar screen 6 is preferably −350 mV or more and +450 mV or less with respect to the reference potential 13. .
[0036]
Note that the potential of the bar screen 6 does not necessarily need to be maintained at a certain potential within the above range, and may fluctuate within the above range.
[0037]
In the antifouling and anticorrosion device 1 having such a configuration, the DC power supply 10 sets the potential of the bar screen 6 to a negative potential with respect to the anode electrode 12. As a result, current flows from the anode electrode 12 to the bar screen 6, and seawater is electrolyzed. As a result, the vicinity of the surface of the bar screen 6 becomes an alkaline atmosphere, an effect of repelling marine organisms is obtained, and the bar screen 6 is soiled.
[0038]
The bar screen 6 is on the cathode side, and is maintained at a potential that can be prevented by the potential control device 11. As a result, the bar screen 6 is maintained in a cathodic protection state in which a current flows from the anode electrode 12 and is protected.
[0039]
As described above, according to the present embodiment, it is not necessary to apply the anticorrosion coating film (and the conductive coating film) to the bar screen 6, and even if the metal surface is used as it is exposed to seawater, The bar screen 6 can be stain- and corrosion-proof.
[0040]
<Second embodiment>
FIG. 4 is a block diagram showing a part of the intake channel 5 of the power plant 100 and a configuration of the antifouling / corrosion preventing device 2 according to the second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0041]
In the present embodiment, an insulating coating (not shown) is first applied to the inner wall surface 51 of the intake channel 5 made of concrete or steel pipe, and conductive coatings 52 and 53 are applied on the insulating coating. I have. This is a measure for preventing the inner wall surface 51 from being stained by supplying electricity to the conductive coating films 52 and 53. In the present embodiment, the conductive coatings 52 and 53 for soiling the inner wall surface 51 are also used for the anode terminal 12 in the first embodiment.
[0042]
The conductive coatings 52 and 53 are insulated from each other at a portion (not shown), and both are set to different potentials by the DC power supply 10 and the polarity switching device 11. As a result, a current flows from the conductive coating film 52 (or 53) having a relatively high (plus) potential to the conductive coating film 53 (or 52) having a relatively low (minus) potential via seawater.
[0043]
The antifouling / anticorrosion device 2 includes a DC power supply device 10, a polarity switching device 20, a potential control device 11, and a reference electrode 13.
[0044]
The anode terminal and the cathode terminal of the DC power supply 10 are connected to the polarity switching device 20 by lead wires L5 and L6, respectively. In addition, the cathode terminal of the DC power supply 10 is connected to the potential control device 11 via a lead wire L7. One terminal of the polarity switching device 20 is connected to the conductive coating 52 via a lead L8, and the other terminal is connected to the conductive coating 53 via a lead L9. One terminal of the potential control device 11 is connected to the reference electrode 13 by a lead L3, and the other terminal is connected to the bar screen 6 by a lead L4.
[0045]
The polarity switching device 20 is supplied with a DC voltage (DC current) from the DC power supply 10 via the lead wires L5 and L6. The polarity switching device 20 switches the polarity of the current supplied from the DC power supply 10 at predetermined time intervals (for example, every two hours) and supplies the current to the conductive coating films 52 and 53. For example, from time T to time (T + 2 hours), a positive potential is applied to the conductive coating 52 and a negative potential is applied to the conductive coating 53, and from the next time (T + 2 hours) to time (T + 4 hours), the conductive coating 52 is applied. A negative potential is applied to the film 52 and a positive potential is applied to the conductive coating 53. Thereafter, these switchings are repeated. The potential of the anode-side conductive coating film 52 (53) is set to, for example, +1.2 to +1.3 V, and the potential of the cathode-side conductive coating film 53 (52) is set to, for example, -0.6 to -0.5 V. Is done.
[0046]
Accordingly, the vicinity of the surface of the conductive coating film 52 (53) on the positive side becomes an acidic atmosphere, and the vicinity of the surface of the conductive coating film 53 (52) on the negative side becomes an alkaline atmosphere. Have. Thereby, antifouling of the inner wall surface 51 of the intake channel 5 is achieved.
[0047]
The potential control device 11 maintains the bar screen 6 at the same potential with respect to the reference electrode 13 as in the above-described first embodiment. Thereby, antifouling and anticorrosion of the bar screen 6 are achieved.
[0048]
As described above, in the present embodiment, by using the conductive coating films 52 and 53 for preventing stain on the inner wall surface 51 of the water intake channel 5 as anode terminals, the existing equipment can be used to prevent the bar screen 6 from being stained. Corrosion protection can be achieved. Thus, the anode electrode 12 in the first embodiment can be omitted.
[0049]
<Third embodiment>
Water intake facilities provided in the water intake channel 5 (for example, metal objects such as an impeller of the circulating water pump 7 and a casing) can also be stain- and corrosion-proof.
[0050]
FIG. 5 is a block diagram showing a configuration of the antifouling / corrosion preventing device 3 for the impeller 71 and the casing 72 of the circulating water pump 7. The same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0051]
The circulating water pump 7 has an impeller 71, a casing 72, and a motor M. The impeller 71 is attached to the rotation shaft of the motor M (or a gear (not shown) attached to the rotation shaft), and rotates with the rotation of the motor M. When the impeller 71 rotates, the seawater in the intake channel 5 flows into the circulating water pipe 5b (see FIG. 1) along the casing 72, and is sent to the condenser 5c (see FIG. 1).
[0052]
The antifouling / anticorrosion device 3 includes a DC power supply device 10, a polarity switching device 20, a potential control device 11, and a reference electrode 13. The DC power supply 10 is connected to the polarity switching device 20 and the potential control device 11 in the same manner as in the second embodiment. The polarity switching device 20 is also connected to the conductive coatings 52 and 53 applied to the inner wall surface 51 of the water intake channel 5 as in the second embodiment.
[0053]
One terminal of the potential control device 11 is connected to the reference electrode 13, and the other terminal is connected to the casing 72 and the conductive brush 30. The conductive brush 30 is provided for short-circuiting the impeller 71 and the casing 72, whereby both can be simultaneously stain- and corrosion-proof.
[0054]
The reference electrode 13 is arranged near the casing 72 or the impeller 71 (for example, at a distance of about 1 mm to several mm) so as not to short-circuit. For example, the reference electrode 13 is attached to the casing 72 with an insulator interposed therebetween.
[0055]
In the present embodiment, similarly to the second embodiment, a current is applied to the conductive coatings 52 and 53 by the DC power supply device 10 and the polarity switching device 20, so that the inner wall surface 51 is stain-proof. . The conductive coatings 52 and 53 also serve as anode terminals, and the casing 72 and the impeller 71 are set to the potential described in the first embodiment with respect to the reference electrode 13 by the potential control device 11. . Thereby, the casing 72 and the impeller 71 are stain- and corrosion-proof. As a result, the antifouling paint and the antifouling paint can be applied to the casing 72 and the impeller 71 without applying the antifouling paint.
[0056]
When the impeller 71 and the casing 72 are made of different metals, the potentials of the impeller 71 and the casing 72 are set to the potential at the portion where the anticorrosion potential of both metals overlaps. For example, when the impeller 72 is made of austenitic stainless steel and the casing 72 is made of carbon steel, the preferable voltage range of the austenitic stainless steel is -1400 mV or more and -600 mV or less with respect to the silver chloride reference electrode 13. The preferred voltage range of steel is -1400 mV or more and -770 mV or less, which is an overlapping portion with -1400 mV or more and -770 mV or less.
[0057]
Of course, it is also possible to apply a current to only one of the impeller 71 or the casing 72, and to perform antifouling and anticorrosion on only one. Further, similarly to the first embodiment, the antifouling and anticorrosion can be performed by providing the anode electrode 12 without using the conductive coating films 52 and 53 as the anode electrode.
[0058]
<Fourth embodiment>
Further, an embodiment will be described in which the present invention is applied to antifouling and anticorrosion of a bar screen provided in an intake channel of an LNG plant facility (hereinafter referred to as “the facility”).
[0059]
FIG. 6 is a block diagram illustrating a schematic configuration of the facility 200. FIG. 7 is a block diagram showing a configuration of the antifouling / corrosion preventing device 2 for performing antifouling / anticorrosion of a part of the water intake passage 205 of the facility 200 and the bar screen 206. Since the same action and effect as those of the antifouling / corrosion preventing apparatus according to the first embodiment are shown, detailed description is omitted.
[0060]
The facility 200 is provided with a water intake passage 205 for taking in seawater. A steel sheet pile 208 is provided near the water intake of the water intake passage 205. A bar screen 206, a travel screen 209, and a seawater pump 207 are provided inside the intake passage 205 in the downstream direction of the intake flow A.
[0061]
The bar screen 206 and the travel screen 209 mainly block dust contained in seawater and prevent dust from entering the seawater pump 207 side. For example, the bar screen 206 is made of steel (carbon steel, alloy steel (stainless steel or the like), cast iron, or the like), and has an outer diameter of H = 10 m and a width of H as shown in the schematic perspective view of FIG. It has a rectangular parallelepiped shape with W = 5 m and thickness (depth) D = 0.2-0.3 m, and a plurality of through-holes 60 having a length of about 0.3 m and a width of about 0.1 m are formed on both front and back surfaces. Has a lattice shape. This lattice shape blocks trash in seawater.
[0062]
The seawater pump 207 pumps seawater and sends the pumped seawater to the LNG vaporizer 205c via the seawater pipe 205b. The supplied seawater is used for vaporizing LNG, and then returned to the ocean via a water discharge pipe 250e.
[0063]
<Other embodiments>
In the embodiment described so far, the antifouling and anticorrosion device of the bar screen or the circulating water pump (the impeller and the casing) has been described. The present invention can be applied to other metal structures (for example, the rotary screen 5 or the like) to be installed.
[0064]
Further, the present invention can be applied not only to the water intake equipment of a power plant but also to a portion of a pier that comes into contact with seawater, a portion of an oil drilling vessel that comes into contact with seawater, and the like, and these can be stain- and corrosion-proof.
[0065]
Further, in the above-described embodiments, a metal structure made of a substance centered on iron such as steel or stainless steel has been described as an example, but the present invention is not limited to such a structure as copper (Cu), titanium (Ti), or the like. The present invention is also applicable to metal objects made of other substances.
[0066]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, antifouling and anticorrosion can be performed without applying antifouling and anticorrosion coating to metal objects placed in seawater, such as a bar screen, a rotary screen, an impeller of a circulating water pump, and a casing.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a power plant.
FIG. 2 is a block diagram showing a part of a water intake channel of a power plant and a configuration of an antifouling / anticorrosion device according to the first embodiment of the present invention.
FIG. 3 is a schematic perspective view of a bar screen.
FIG. 4 is a block diagram showing a configuration of a part of an intake channel of a power plant and an antifouling / corrosion preventing apparatus 2 according to a second embodiment of the present invention.
FIG. 5 is a block diagram showing a configuration of an antifouling / corrosion preventing device according to a third embodiment of the present invention.
FIG. 6 is a block diagram showing a schematic configuration of LNG plant equipment.
FIG. 7 is a block diagram showing a part of an LNG plant facility and a configuration of an antifouling / corrosion preventing apparatus of the present invention.
[Explanation of symbols]
Reference Signs List 5 Intake channel 51 Inner wall surface 52, 53 of intake channel Conductive coating film 6 Bar screen 7 Circulating water pump 71 Impeller 72 Casing 10 DC power supply device 11 Potential control device 12 Anode electrode 13 Reference electrode 20 Polarity switching device 30 Conductive brushes L1 to L9 Lead

Claims (9)

An antifouling and anticorrosion device for metal objects placed in seawater,
A reference electrode that is placed in seawater and has a known potential in seawater depending on the substance used;
An anode electrode placed in seawater,
The metal object, the reference electrode, and connected to the anode electrode, the anode electrode to a relatively high potential, while the metal object to a relatively low potential, based on the potential of the reference electrode, Power supply means for turning a metal object to a potential capable of preventing corrosion;
Anti-fouling and anti-corrosion equipment. In claim 1,
The power supply means, the metal object, can be anticorrosive, and a potential at which organisms in seawater do not adhere to the metal object, or a potential at which the adhesion of compounds in seawater to the metal object does not proceed,
Antifouling and anticorrosion equipment. In claim 1 or 2,
The power supply has a potential control device and a DC power supply,
In the DC power supply device, the anode terminal is connected to the anode electrode, and the cathode terminal is connected to the potential control device,
The potential control device is configured such that the reference electrode is connected to one terminal, the metal object is connected to the other terminal, the potential of the reference electrode is detected, and the metal object is detected based on the detected potential. The anticorrosive potential,
Antifouling and anticorrosion equipment. In claim 3,
The potential control device,
Detecting means for detecting the potential of the reference electrode,
A variable resistor,
A control unit that adjusts the resistance value of the variable resistor based on the potential detected by the detection unit, and controls the potential of the metal object to a potential that can prevent corrosion;
Anti-fouling and anti-corrosion equipment. In any one of claims 1 to 4,
An antifouling and anticorrosion device, wherein the reference electrode is made of silver / silver chloride or zinc. In any one of claims 1 to 5,
The antifouling and anticorrosion device, wherein the anode terminal is a conductive coating film provided with the metal object and applied to an inner wall surface of a water channel for guiding seawater. In claim 6,
The conductive coating is separated into two mutually insulated first and second portions;
The power supply unit has a polarity switching unit that switches a polarity of electricity of the first portion and the second portion,
The polarity switching means switches the polarity of the first portion and the second portion at predetermined time intervals, and from the portion having at least the polarity of the anode among the first portion and the second portion. Apply current to metal objects,
Antifouling and anticorrosion equipment. In any one of claims 1 to 7,
The anode electrode and the metal object, the density of the current flowing from the anode electrode to the metal object is arranged at a distance that is substantially constant at each location of the metal object,
Antifouling and anticorrosion equipment. In any one of claims 1 to 8,
The reference electrode is disposed near the metal object.
Antifouling and anticorrosion equipment.

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