JP6276124B2 - Cathodic protection method and cathodic protection system - Google Patents

Description

  The present invention relates to an anticorrosion method and an anticorrosion system for performing anticorrosion on piping and the like.

  Electro-corrosion is to prevent corrosion of metal by flowing anti-corrosion current that is opposite to the corrosion current that flows in metal, and has been applied to offshore structures (concrete structures, bridges, etc.). . On the other hand, recently, it has been applied to oil mining plants and desalination plants. As a specific application site, it is used to prevent local corrosion such as pitting corrosion and crevice corrosion in metal pipes and metal pumps constituting the plant (see Patent Documents 1 and 2).

  In patent document 3, after setting the anti-corrosion voltage applied to an anti-corrosion object, when the anti-corrosion current which flows through an anti-corrosion object falls below a fixed value, the system which operates a washing | cleaning apparatus and recovers and maintains an anti-corrosion current is disclosed. doing.

JP 2013-245380 A JP 2014-9362 A JP 2004-269997 A

  However, in Patent Documents 1 and 2, only yearly inspection is performed, and control for electrode deterioration and environmental change is not performed. Further, in Patent Document 3, control corresponding to electrode deterioration and environmental change is performed, but it depends on an external process such as cleaning of piping and the like. Therefore, the effect of preventing corrosion of pipes and the like is scarce regardless of which anticorrosion system is applied, and in particular, it cannot respond to sudden fluctuations in water quality or surface changes of pipes, etc. It was difficult to suppress the progress of local corrosion.

  Therefore, the present invention pays attention to the above-mentioned problems, and an anticorrosion method and an anticorrosion system for reliably performing the anticorrosion of the distribution path in response to sudden changes in water quality and surface changes of the distribution path such as piping. The purpose is to provide.

In order to achieve the above object, the cathodic protection system of the present invention includes an anode that is electrically insulated from a metal flow path portion through which a fluid flows and contacts a fluid that flows through the flow path portion, and the flow path portion. An anti-corrosion power source for applying an anti-corrosion voltage between the anode and the anode and causing the anti-corrosion current to flow through the flow path part, a measuring means for measuring the anti-corrosion voltage and the anti-corrosion current, and the anti-corrosion current is equal to or less than a predetermined current value A control unit that controls the anticorrosion power supply to increase the anticorrosion voltage so that the anticorrosion current becomes the current value when the anticorrosion current becomes The control unit controls the switching of the switching unit so that the connection destination of the anode is the ground terminal when the anticorrosion voltage exceeds the upper limit voltage. To do And butterflies. With the above configuration, generation of harmful gas and the like can be suppressed, and the anode can be grounded to cancel the charged state and return the anode to the initial state, thereby restoring the anticorrosion ability for the flow path.

  According to the cathodic protection method and the cathodic protection system according to the present invention, since the anticorrosion current is always adjusted to maintain a constant current value, the flow path portion of the flow path portion caused by a change in the water quality or a change in the surface state of the flow path portion. Corrosion protection can be performed in response to changes in corrosion conditions. Thereby, a corrosion trouble can be reduced and the operating rate of a plant can be improved. In particular, when the distribution path is a pipe, the pipe life is improved by suppressing the occurrence of local corrosion. Thereby, since the pipe replacement frequency is also reduced, the running cost of the plant can be reduced. In addition, since the environmental potential of the distribution path portion can be always lower than the potential that becomes the active area of the corrosion of the material of the distribution path portion, it is possible to surely prevent corrosion of the distribution path portion. Furthermore, while suppressing the generation of harmful gases, etc., a voltage is applied to reduce the anode, or the ground is grounded to eliminate the charged state and return the anode to the initial state, thereby restoring the anticorrosion ability for the flow path section. be able to.

It is a schematic diagram of the cathodic protection system of this embodiment. It is a schematic diagram of the desalination plant used as the application object of the cathodic protection system of this embodiment. It is a partial detailed view (sectional view) of the cathodic protection system of this embodiment. It is a figure which shows the operation | movement flow of the cathodic protection system of this embodiment. It is a figure which shows the 1st modification of the partial detail drawing (sectional drawing) of the cathodic protection system of this embodiment. It is a figure which shows the 2nd modification of the partial detailed view (sectional drawing) of the cathodic protection system of this embodiment.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  In FIG. 2, the schematic diagram of the desalination plant used as the application object of the cathodic protection system of this embodiment is shown. As shown in FIG. 2, in the desalination plant 100, fresh water is generated from seawater (fluid) using a plurality of reverse osmosis membrane units 116. In the reverse osmosis membrane, the water to be filtered (seawater) is separated into filtered water (fresh water) and concentrated water, but in FIG. 2, the path of the concentrated water is omitted.

  As shown in FIG. 2, in the desalination plant 100, when seawater is introduced from the outside, the pressure is increased by the pump 114 and supplied to the reverse osmosis membrane unit 116. The desalination plant 100 is formed by a pump 114 (distribution path unit 102), a pipe 104 (distribution path unit 102), and a reverse osmosis membrane unit 116. In the desalination plant 100, the piping 104 is branched downstream of the pump 114 and connected to the plurality of reverse osmosis membrane units 116, or the piping 104 through which filtered water (fresh water) downstream of the plurality of reverse osmosis membrane units 116 circulates. The two are connected in parallel. The pump 114 and the pipe 104 are made of metal such as stainless steel, and the reverse osmosis membrane unit 116 is made of an insulator. Therefore, in the desalination plant 100, when all the pipes 104 and the pumps 114 are not electrically connected, the segment-shaped flow path portions 102 (portions surrounded by broken lines in FIG. 2) that are electrically separated from each other are reversed. A plurality of permeable membrane units 116 are formed. On the other hand, when all pipes and pumps are electrically connected, or when the same water quality and the same pipe (pump) material are used in the entire desalination plant without electrically connecting all the pipes and pumps, It can be considered that there is a single distribution channel in the desalination plant 100.

  In FIG. 2, the above-described distribution path portions 102 are formed in four places, and the cathodic protection system 10 of the present embodiment is applied to each distribution path portion 102. Therefore, when the pressure and salt concentration of seawater differ for every distribution channel part 102, the optimal anti-corrosion can be performed in each distribution channel part 102 based on the difference. In addition, the cathodic protection system 10 of this embodiment is applied also to the distribution | circulation route part (not shown in FIG. 2) through which concentrated water distribute | circulates.

  In FIG. 1, the schematic diagram of the cathodic protection system of this embodiment is shown. The cathodic protection system 10 of the present embodiment is configured such that the flow path portion 102 is electrically insulated from a metal flow path portion 102 (pipe 104, pump 114 (not shown in FIG. 1)) through which fluid (seawater) flows. An anode 12 that is in contact with a fluid (seawater) that circulates, and an anticorrosion power source 20 that applies an anticorrosive voltage between the circulation path portion 102 and the anode 12 to cause the corrosion path current to flow through the circulation path portion 102. Have. Further, the measurement means for measuring the anticorrosion voltage and the anticorrosion current (included in the anticorrosion power supply 20 in this embodiment), and when the anticorrosion current becomes a predetermined current value or less, the anticorrosion current is not less than the current value. And a controller 40 that controls the anticorrosion power source 20 to increase the anticorrosion voltage.

  On the other hand, in the flow path portion 102, a plurality of pipes 104 (or pumps 114) are connected in series (or in parallel) by flange connection, but the end portions thereof are reverse osmosis membrane units 116 (not shown in FIG. 1). )It is connected to the.

  The anode 12 is, for example, a ring-shaped material (see FIG. 3), and is disposed so as to be sandwiched between two pipes 104 adjacent to each other. As will be described later, the anode 12 is in contact with the seawater in the pipe 104 but is not electrically connected to the pipe 104.

  The anticorrosion power supply 20 is a direct current power supply. When the information on the applied voltage is input from the control unit 40, the anticorrosion voltage based on the information on the applied voltage is supplied to the anode 12, the pipe 104, and the like (the pump 114 may be included). In between. At this time, a positive (possibly negative) voltage is applied to the anode 12 and a negative (possibly positive) voltage is applied to the pipe 104 and the like. By applying this anticorrosion voltage, an anticorrosion current flows from the anode 12 to the pipe 104 and the like through seawater. Further, the anticorrosion power supply 20 includes a voltmeter (measuring means) and an ammeter (measuring means), and outputs the information on the anticorrosion voltage and the information on the anticorrosion current that are output.

  The potential measuring means takes out seawater flowing through the pipe 104 and measures the potential of the seawater as the pipe potential. The potential measuring means includes a branch pipe 22 (branch path), a water tank 28, and a potentiometer 30. The branch pipe 22 is attached to the pipe 104 and discharges a part of the seawater flowing in the pipe 104 and the like to the water tank 28. The pressure reducing valve 24 is arranged in the middle, and the opening / closing valve 26 is arranged at the end. Yes. It is preferable that the seawater stored in the water tank 28 is always flowing water with the opening / closing valve 26 always open, but the seawater may be replaced about once a week.

  The potentiometer 30 measures the potential difference between a reference electrode 32 (known electromotive force by the reference electrode 32) and a reference electrode 34 (electromotive force by the reference electrode 34) immersed in seawater stored in the water tank 28. Seawater, that is, the pipe potential of the pipe 104 through which seawater flows is measured. Information on the piping potential calculated by the potentiometer 30 is output to the control unit 40. Here, the reference electrode 32 may be an electrode for electrochemical measurement such as a silver-silver chloride electrode, or a noble metal and a metal / metal oxide with a stable potential in the environment. The reference electrode 34 is connected to a pipe (104, 106A, 106B) or the like.

  The switch 36 (switching means) switches the connection destination of the anode 12 by a switching signal from the control unit 40. Normally, the switch 36 connects the anode 12 to the anticorrosion power supply 20, but switches the anode 12 to the ground terminal 38 in accordance with the switching signal described above.

  The control unit 40 is an application installed in a PC (personal computer), for example, and controls the cathodic protection system 10 of the present embodiment. The control unit 40 is connected to the anticorrosion power supply 20, the potentiometer 30, and the switch 36 via an interface (not shown). The control unit 40 outputs the information on the applied voltage to the anticorrosion power supply 20 and receives the information on the anticorrosion voltage and the information on the anticorrosion current from the anticorrosion power supply 20. In addition, pipe potential information is input from the potentiometer 30 to the control unit 40. Further, the control unit 40 outputs a switching signal to the switch 36. Further, the anticorrosion setting information (to be described later) is input by a keyboard or mouse attached to the PC and stored in the storage area of the PC, and the control unit 40 reads the stored anticorrosion setting information as necessary. Take control.

  In FIG. 3, the fragmentary detailed view (sectional drawing) of the cathodic protection system of this embodiment is shown. The pipes are connected by connecting the bolt 110 to the insertion hole 108 formed in the flange 106 </ b> A and the flange 106 </ b> B facing each other, and tightening the bolt 110 with the bolt 110 and the nut 112. Therefore, in the present embodiment, the anode 12 sandwiched between the two insulating materials 16A and 16B is sandwiched and fixed between the one flange 106A and the other flange 106B.

  The insulating materials 16 </ b> A and 16 </ b> B have a ring shape like the anode 12 and are designed so that the inner diameter thereof is substantially the same as the inner diameter of the pipe 104. Then, the flange 106A, the insulating material 16A, the anode 12, the insulating material 16B, and the flange 106B are aligned in that order in the flow direction of the seawater and are fastened together by the bolt 110 and the nut 112 in a concentric state. The insulating materials 16A and 16B are formed with insertion holes 18 through which the bolts 110 are inserted, and the anode 12 is also formed with insertion holes 14 through which the bolts 110 are inserted. However, the insertion hole 14 of the anode 12 is designed to have an inner diameter larger than that of the insertion hole 18 so that the anode 12 does not contact the bolt 110. The inner wall of the insertion hole 14 is covered with an insulating material (in the form of a thin film).

  As shown in FIG. 3, the anode 12 is in contact with seawater that is inside the ring. The adjacent pipes 104 are electrically connected via bolts 110. Therefore, regardless of the anticorrosion current from the anticorrosion power supply 20, the potentials of all the pipes 104 and the like in the flow path unit 102 are equal. On the other hand, since the bolt 110 only passes inside the insertion hole 18, the bolt 110 and the anode 12 are electrically insulated from each other. Thereby, the anticorrosion voltage can be applied between the anode 12 and the pipe 104 or the like. Here, the material of the anode 12 is preferably titanium, platinum, graphite or the like. The insulating materials 16A and 16B may be formed of rubber or the like.

  In the present embodiment, the anticorrosion of the pipe 104 can be performed by applying an anticorrosion voltage in which the anode 12 has a positive voltage and the pipe 104 or the like has a negative voltage to flow an anticorrosion current through the pipe 104 or the like. However, the anti-corrosion current may drop below the value required for anti-corrosion due to sudden fluctuations in the state of seawater. In this case, it is necessary to increase the anticorrosion current by increasing the anticorrosion voltage.

  Further, when active dissolution of the metal structure or microbial corrosion occurs in the pipe 104 or the like, the pipe potential (environmental potential of the pipe 104 or the like) increases from the initial potential immediately after the start of corrosion prevention. At this time, the piping potential reaches the range that becomes the active region beyond the range of the potential that becomes inactive against corrosion. In this case, it is necessary to increase the anticorrosion voltage and lower the piping potential to the initial potential.

  Furthermore, marine organisms and scale (precipitates such as calcium) adhere to the pipe 104 and the like, and the anticorrosion current may not flow easily. This can be determined by the fact that the anticorrosion current is equal to or lower than the expected value even if the above-described operation for reducing the environmental potential to the initial voltage is performed. In this case, the deposit 12 is removed by applying a voltage opposite to the anticorrosion voltage so that the anode 12 has a negative voltage and the pipe 104 has a positive voltage, or the deposit is removed by chemical injection treatment. There is a need to.

  On the other hand, the anode 12 may be oxidized and deteriorated when used for a long time. At this time, even if the anticorrosion voltage is increased, it is difficult to increase the anticorrosion current and to reduce the piping potential of the piping 104 and the like. In this case, in order to reduce the anode 12, an anticorrosion voltage in a reverse direction in which the anode 12 has a negative voltage and the pipe 104 and the like have a positive voltage is applied, or the anode 12 is connected to the ground terminal 38. It is necessary to eliminate the charged state.

  In general, in the pipe 104, local corrosion (crevice corrosion) tends to proceed at the connecting portions such as the flanges 106A and 106B. However, in the cathodic protection system 10 of the present embodiment, the corrosion of the pipe 104 and the like can be reduced by detecting any of the above states and controlling the anticorrosion voltage.

As the anti-corrosion setting information required by the control unit 40, information on the anti-corrosion area (contact area with seawater) of the anti-corrosion object, information on the current density I [A / cm ² ] necessary for anti-corrosion, and increasing the anti-corrosion voltage Information on the increased voltage amount (a1 [V], a2 [V]), information on the number of stages when increasing step by step to the increased voltage amount, and voltage at that stage when increasing stepwise to the increased voltage amount Information on the waiting time between the increase and the voltage increase in the next stage, information on the amount of increase in the piping potential (b [V]) determined to be increased by the increased voltage amount, and allowed by the anticorrosion power supply 20 There is information on the upper limit voltage (Vmax [V]), information on an expected value of the anticorrosion current (K [A] (> J [A])) for determining that the cleaning process is necessary for the pipe 104, and the like.

  The above information (anticorrosion setting value) is appropriately determined depending on the material of the pipe 104 to be applied, the cross-sectional area of the cavity through which seawater flows, the shape and material of the anode 12, the composition, temperature, pressure, flow rate, etc. of the seawater. It is decided. For example, the upper limit voltage (corrosion protection voltage) is determined in consideration of an allowable product gas, pH, residual salt concentration, and the like based on environmental assessment. Further, the information on the increased voltage amount a1 is obtained by previously investigating the relationship between the increased amount of the applied voltage (corrosion protection voltage) and the increased amount of the corrosion current, and the information on the increased voltage amount a2 is the increase amount of the applied voltage (corrosion protection voltage). Is determined by investigating in advance the relationship between the amount of decrease in the pipe potential and the amount of decrease in the pipe potential. Similarly, the information on the increase amount b of the pipe potential is determined by examining in advance the upper limit at which the pipe potential is equal to or less than the potential of the corrosion active region of the material such as the pipe 104, but the value should be about 100 mV. Is desirable.

  In FIG. 4, the operation | movement flow of the cathodic protection system of this embodiment is shown. Next, the operation | movement flow of the cathodic protection system 10 of this embodiment is demonstrated. First, the above-described anticorrosion set value applicable to the anticorrosion target pipe 104 or the like is input by a key operation or the like. The anticorrosion area (contact area with seawater) of the anticorrosion target pipe 104 and the like is calculated, and the information (anticorrosion set value) is stored in the storage area of the PC by a key operation or the like (step 1). Further, other anticorrosion setting values related to control are also stored by key operation or the like.

  The control unit 40 calculates the value of the anticorrosion current that flows through the pipe 104 or the like based on the information on the anticorrosion area and the information on the current density (J [A]), and the anticorrosion current (J [A]) calculated in the pipe 104 or the like. ) Is output to the anticorrosion power supply 20 so that the current flows) (step 2). As a result, the anticorrosion power source 20 applies an anticorrosion voltage between the anode 12 and the pipe 104 and the like, and an anticorrosion current (J [A]) flows through the pipe 104 and the like. At this time, since the pipe potential is lower than the immersion potential of the pipe 104 or the like (becomes an initial potential), the anticorrosion can be performed on the pipe 104 or the like. The anticorrosion current flows from the anode 12 to the pipe 104 and the like via seawater. The anticorrosion power supply 20 outputs information on the anticorrosion current and information on the anticorrosion voltage to the control unit 40. Thereby, the control part 40 can monitor the anticorrosion current which flows through the piping 104 grade | etc.,.

  The control when the anticorrosion current is lower than the specified value (J [A]) will be described. When the anticorrosion current is lower than J [A] (step 3), more specifically, when the state where the anticorrosion current is lower than J [A] continues for a predetermined time or longer, the control unit 40 Is increased by a1 [V] (step 4). At this time, it is not increased to a1 [V] at a time, but is increased in a plurality of stages based on the information on the number of stages described above, and each time it waits until the anticorrosion current is stabilized based on the information on the waiting time. Then increase the voltage. And the above-mentioned step 3 and step 4 are repeated on condition that an anticorrosion voltage is below the upper limit voltage Vmax [V] (step 5).

  On the other hand, when the anticorrosion voltage is equal to or higher than the upper limit voltage Vmax [V], the control unit 40 stops applying the anticorrosion voltage and outputs a switching signal to connect the connection destination of the anode 12 to the ground terminal 38. Alternatively, the charged state of the anode 12 is canceled by applying a voltage in the direction opposite to the anticorrosion voltage (step 6). Thereafter, the process returns to step 3 again.

  Next, control when the piping potential increases will be described. When the pipe potential increases by b [V] from the initial potential (Step 7), the control unit 40 increases the anticorrosion voltage by a2 [V] (Step 8). At this time, it is not increased to a2 [V] at a time, but is increased in a plurality of stages based on the information on the number of stages described above, and each time it waits until the anticorrosion current is stabilized based on the information on the waiting time. Then increase the voltage. The anticorrosion voltage is equal to or lower than the upper limit voltage Vmax [V] (step 9), the pipe potential has returned to the initial potential (step 10), and the anticorrosion current has reached the expected value G [A] (step) Step 7 and Step 8 described above are repeated on condition 11).

  On the other hand, when the anticorrosion voltage becomes equal to or higher than the upper limit voltage Vmax [V] (step 8), or when the pipe potential does not return to the initial potential (step 9), step 6 is performed in the same manner as described above, and then the step Return to 7.

  If the anticorrosion current does not reach the expected value G [A] (> J [A]), a voltage in the direction opposite to the anticorrosion voltage is applied to the anode 12 and the pipe 104 to adhere to the pipe 104 and the like. The attached matter is removed by removing the attached matter such as the marine marine or the scale or the chemical injection process for the pipe 104 or the like (step 12), and then the process returns to step 7.

  The anticorrosion current frequently changes with short-term changes in the state of seawater flowing through the pipe 104 and the like, and the state of the surface of the pipe 104 and the like. On the other hand, the increase in piping potential occurs when active dissolution of the metal structure or microbial corrosion occurs, and the change is slower than the change in the anticorrosion current. Therefore, in the control part 40, the frequency | count of control by the reduction | decrease in anticorrosion current becomes larger than the frequency | count of control by the raise of piping potential.

  As described above, according to the cathodic protection system 10 according to the present embodiment, the anticorrosion current is adjusted so as to always maintain a constant current value (J [A]). Corrosion prevention can be performed in response to changes in the corrosion conditions of the flow path portion 102 caused by changes in the surface state of the (pipe 104, pump 114). Thereby, a corrosion trouble can be reduced and the operating rate of a plant can be improved. In particular, when the distribution channel 104 is the pipe 104, the pipe life is improved by suppressing the occurrence of local corrosion. Thereby, since the pipe replacement frequency is also reduced, the running cost of the plant can be reduced. Since the environmental potential (pipe potential) of the flow path part 102 can be always lower than the potential that becomes the active area of the corrosion of the material of the flow path part 102, the anti-corrosion for the flow path part 102 can be reliably performed.

  Furthermore, by providing an upper limit voltage (Vmax [V]), the generation of harmful gases and the like is suppressed, and a voltage is applied so as to reduce the anode 12, or the charged state is eliminated by grounding, whereby the anode 12 Can be restored to the initial state, and the anticorrosion ability for the flow path portion 102 (the pipe 104, the pump 114) can be restored.

  And it has the branch path (branch pipe 22) branched from the said flow path part 102 (the piping 104, the pump 114), and the water tank 28 which stores the fluid (seawater) which flowed out from the said branch path, The said electric potential measurement The means (potentiometer 30) measures the potential of the flow path section 102 based on the reference electrode 32 immersed in the fluid stored in the water tank 28, and a pressure reducing valve 24 is provided in the branch path. Thereby, even if the fluid flowing through the flow path part 102 (pipe 104, pump 114) is at a high pressure, the fluid can be reliably taken out without closing the flow path part 102, and the reference electrode 32 is also connected to the flow path part 102. Therefore, the electric potential measuring means can be easily maintained.

  In FIG. 5, the 1st modification of the partial detailed view (sectional drawing) of the cathodic protection system of this embodiment is shown. The flange connection structure of the pipe shown in the first modification is the same as the flange connection shown in FIG. 2, but here, the bolt 110 is formed of an insulating material (ceramic or the like), and the pipe 104 (flange 106A) Electrical connection with the pipe 104 (flange 106B) is performed by a conductive wire 118 (jumper wire). In this case, since there is no short circuit between the pipe 104 and the anode 12 via the bolt 110, the insertion hole 14 through which the bolt 110 is inserted need not be larger than the other insertion holes.

  In FIG. 6, the 2nd modification of the partial detailed view (sectional drawing) of the cathodic protection system of this embodiment is shown. The anode shown in the above-described embodiment is connected to the pipe in a mode of being sandwiched between the pipe 104 (flange 106A) and the pipe 104 (flange 106B). On the other hand, in the second modification, a flange portion 120 that communicates with the inside of the pipe 104 is formed on the side wall in the longitudinal direction of the pipe 104, and a seat 124 that seals the circular opening 122 of the flange section 120 (for example, (Circle) is attached by bolting using a bolt 126. The seat 124 and the bolt 126 are preferably made of the same material as the pipe 104. On the other hand, the insulating coating lead 128 connected to the switch 36 (corrosion protection power supply 20) passes through the seat 124, and the insulating coating lead 128 is connected to the anode 12. The anode 12 is connected to the seat 122 via an insulating adhesive layer 130 such as resin, and is designed to be smaller than the inner diameter of the opening 120.

  In the above configuration, the seat 124 is electrically connected to the pipe 104, but is insulated from the insulating coating conductor 128. The anode 12 is bonded to the seat 124 by the adhesive layer 130, but is electrically insulated from the seat 124. Therefore, the anode 12 is electrically insulated from the pipe 104. In the second modification, the anode 12 can be replaced simply by removing the seat 124 without releasing the flange connection of the pipe 104, so that the anode 12 can be easily replaced.

  In the present embodiment, the fluid flowing through the pipe 104 and the like has been described on the assumption that seawater or fresh water obtained by filtering seawater with a reverse osmosis membrane, and concentrated water, but other fluids having electrical conductivity. Is also applicable. The branch pipe 22 is branched from the pipe 104, but may be branched from the pump 114.

  The present invention can be used as an anticorrosion method and an anticorrosion system for reliably performing the anticorrosion of the distribution path in response to sudden fluctuations in water quality and surface changes of the distribution path such as piping.

10 ......... Anticorrosion system, 12 ......... Anode, 14 ......... Insertion hole, 16A, 16B ......... Insulating material, 18 ......... Insertion hole, 20 ......... Anticorrosion power supply, 22 ......... Branch tube 24 ......... Pressure reducing valve, 26 ......... Open / close valve, 28 ......... Water tank, 30 ......... Potentiometer, 32 ......... Reference electrode, 34 ......... Reference electrode, 36 ......... Switch, 38 ... ...... Ground terminal, 40... Control section, 100... Desalination plant, 102... Distribution channel section, 104 ... Pipe, 106 A, 106 B ... Flange, 108 ... Insert hole, 110 ......... Bolt, 112 ...... Nut, 114 ......... Pump, 116 ......... Reverse osmosis membrane unit, 118 ......... Conductor, 120 ......... Flange, 122 ......... Opening, 124 ......... Seat, 126 ......... bolt, 128 ......... insulating conductive wire, 13 ......... adhesive layer.

Claims (4)

An anode in contact with the fluid flowing through the flow path portion while being electrically insulated from the metal flow path portion through which the fluid flows;
An anti-corrosion power source that applies an anti-corrosion voltage between the flow path part and the anode to flow an anti-corrosion current to the flow path part;
Measuring means for measuring the anticorrosion voltage and the anticorrosion current;
A control unit that controls the anticorrosion power source to increase the anticorrosion voltage so that the anticorrosion current becomes the current value when the anticorrosion current becomes a predetermined current value or less,
A switching means capable of switching the connection destination of the anode between the anticorrosion power source and the ground terminal,
Wherein, the when the corrosion protection voltage exceeds the upper limit voltage, gas anticorrosion system power you and performs switching control of said switching means so that the anode of the connection destination is the ground terminal. Having an electric potential measuring means for measuring the environmental potential of the distribution channel part;
The control unit controls the anticorrosion power supply to increase the anticorrosion voltage so that the environmental potential becomes lower than the predetermined potential when the environmental potential becomes higher than the predetermined potential. The cathodic protection system according to claim 1 . Wherein, when the corrosion voltage exceeds the upper limit voltage, the control and the anti-corrosion voltage to the anode for applying a reverse voltage to claim 1 or 2, characterized in that said anticorrosive power supply The described cathodic protection system. A branch path branched from the distribution path section;
A water tank for storing the fluid discharged from the branch path,
The potential measuring means measures the environmental potential based on a reference electrode immersed in a fluid stored in the water tank,
The anticorrosion system according to claim 2, wherein a pressure reducing valve is provided in the branch path.

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