Electric protection device

Abstract

To determine a replacement time of a sacrificial anode.SOLUTION: An electric protection device 10 comprises: a pump 14 provided on a pipe 12 and feeding sea water to a sea water supply object 32 and discharging the sea water therefrom; a first pressure sensor 15 which detects a pressure in a first pipe part 12A which connects the pump 14 in the pipe 12 and the sea water supply object 32; a second pressure sensor 16 which detects a pressure in a second pipe part 12B which connects the pump 14 in the pipe 12 and submarine 30; a sacrificial anode 21 arranged in the second pipe part 12B; and a replacement time determination part 18a for determining the replacement time of the sacrificial anode 21 on the basis of the pressure difference between the detection values of the first pressure sensor 15 and the second pressure sensor 16.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to an electric corrosion protection device.

Background Art

[0002] Conventionally, for example, there is a galvanic anode type electric corrosion protection device described in Patent Document 1. The electric corrosion protection device suppresses the consumption (dissolution) of the sacrificial anode and extends the service life of the sacrificial anode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to Patent Document 1, it does not have a means for grasping the replacement timing of the sacrificial anode. Therefore, after the sacrificial anode is completely melted, it is impossible to secure the electrons necessary for corrosion protection, and the steel material may rust.

[0005] The problem to be solved by the technology disclosed in this specification is to determine the replacement timing of the sacrificial anode.

Means for Solving the Problems

[0006] To solve the above problems, the technology disclosed in this specification takes the following means.

[0007] The first means is an electrocorrosion protection device for protecting the inner surface of a pipe connecting the sea and a seawater supply target. The device includes a pump provided in the pipe for supplying and discharging seawater to and from the seawater supply target, a first pressure sensor for detecting the pressure in a first pipe section of the pipe that connects the pump and the seawater supply target, a second pressure sensor for detecting the pressure in a second pipe section of the pipe that connects the pump and the sea, a sacrificial anode disposed in the second pipe section, and an exchange timing determination unit for determining the replacement timing of the sacrificial anode based on the differential pressure between the detection value of the first pressure sensor and the detection value of the second pressure sensor.

[0008] According to the first means, based on the differential pressure between the detection value of the first pressure sensor that detects the pressure in the first pipe section connecting the pump and the seawater supply target and the detection value of the second pressure sensor that detects the pressure in the second pipe section connecting the pump and the sea, the dissolved state (consumed state) of the sacrificial anode is grasped. Thereby, the replacement timing of the sacrificial anode can be determined.

[0009] The second means is the electrocorrosion protection device of the first means, wherein the exchange timing determination unit determines the replacement timing of the sacrificial anode when the differential pressure between the detection value of the first pressure sensor and the detection value of the second pressure sensor is equal to or greater than a specified value based on the decrease in the cross-sectional area of the sacrificial anode.

[0010] According to the second means, the replacement timing of the sacrificial anode can be accurately determined.

Effect of the Invention

[0011] According to the technology disclosed in this specification, the replacement timing of the sacrificial anode can be determined.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments for carrying out the technology disclosed in this specification will be described with reference to the drawings. FIG. 1 is a schematic view showing an impressed current cathodic protection device, FIG. 2 is a view taken along the line II-II of FIG. 1, and FIG. 3 is a sectional view taken along the line III-III of FIG. 2. As shown in FIG. 1, the impressed current cathodic protection device 10 protects the inner surface of a pipe 12 that connects the sea 30 and a seawater supply target 32. The pipe 12 is formed in a circular pipe shape from steel material (Fe). For this reason, the pipe 12 corrodes due to the dissolution of + ions into the seawater.

[0014] A pump 14 for supplying and discharging seawater to and from the seawater supply target 32 is provided in the pipe 12. That is, during water supply, the pump 14 supplies the seawater pumped up from the sea 30 to the seawater supply target 32 (see arrow Ya in FIG. 1), and during drainage, the pump 14 drains the seawater pumped up from the seawater supply target 32 into the sea 30 (see arrow Yb in FIG. 1). Among the pipe 12, the pipe section connecting the pump 14 and the seawater supply target 32 is referred to as a first pipe section 12A, and the pipe section connecting the pump 14 and the sea 30 is referred to as a second pipe section 12B.

[0015] A first pressure sensor 15 is provided in the first pipe section 12A. The first pressure sensor 15 detects the pressure in the first pipe section 12A and outputs an electric signal corresponding to the detected value to an ECU 18, which is an electronic control device. A second pressure sensor 16 is provided in the second pipe section 12B. The second pressure sensor 16 detects the pressure in the second pipe section 12B and outputs an electric signal corresponding to the detected value to the ECU 18.

[0016] Inside the second pipe section 12B, a sacrificial anode unit 20 immersed in seawater is arranged. The sacrificial anode unit 20 has a sacrificial anode 21, a support fitting 22, and a pair of upper and lower pedestals 23 (see FIGS. 2 and 3). The sacrificial anode 21 is formed in a square bar shape from a metal having a lower potential than the pipe 12, for example, an aluminum (Al) material. The cross-section of the sacrificial anode 21 is formed in a trapezoidal shape. The sacrificial anode 21 supplies electrons to the second pipe section 12B and moves the potential in the - (minus) direction up to the inactive region of the second pipe section 12B, thereby suppressing i.e., preventing the progress of corrosion on the inner surface of the second pipe section 12B. The sacrificial anode 21 melts away by continuously supplying electrons to the second pipe section 12B.

[0017] The support fitting 22 is made of a steel wire material (Fe) and is embedded so as to penetrate longitudinally (vertically) inside the sacrificial anode 21. Both ends of the support fitting 22 protrude from both ends of the sacrificial anode 21 and are bent in an L shape.

[0018] The pedestal 23 is made of a steel material (Fe) and is formed in an arc plate shape following the circumferential direction of the inner surface of the second pipe section 12B (see FIG. 2). As shown in FIG. 2, screw holes 23a are formed at both ends of the pedestal 23. The pair of pedestals 23 are arranged parallel to each other vertically (see FIGS. 1 and 3). Both ends of the support fitting 22 are joined by welding to the central portions of the inner surfaces of the pair of pedestals 23. Also, bolt insertion holes 25 corresponding to the screw holes 23a of both pedestals 23 are formed in the second pipe section 12B.

[0019] As shown in FIG. 1, the sacrificial anode unit 20 is attached to the second pipe section 12B by a total of four bolts 27 in a state of being arranged inside the second pipe section 12B. Each bolt 27 is tightened into each screw hole 23a of each pedestal 23 through each bolt insertion hole 25 of the second pipe section 12B (see FIG. 2).

[0020] Both pressure sensors 15 and 16 and pump 14 are connected to ECU 18. The ECU 18 controls the power supply to both pressure sensors 15 and 16 and pump 14 and the operation timing thereof. The ECU 18 includes an exchange timing determination unit 18a that determines the exchange timing of the sacrificial anode 21 based on the signals output from both pressure sensors 15 and 16 during the operation of pump 14. The exchange timing determination unit 18a determines that it is the exchange timing of the sacrificial anode 21 when the differential pressure (pressure loss) between the detected value of the first pressure sensor 15 and the detected value of the second pressure sensor 16 is equal to or greater than a predetermined value based on the decrease in the cross-sectional area of the sacrificial anode 21.

[0021] Specifically, when the sacrificial anode 21 has not melted and the amount of melting is small (see FIG. 1), the cross-sectional area of the sacrificial anode 21 is large. For this reason, due to the pressure loss caused by the sacrificial anode 21, the flow rate in the pipe 12 at a predetermined pump rotational speed is small. Further, when the amount of melting of the sacrificial anode 21 increases, the cross-sectional area of the sacrificial anode 21 decreases, that is, the sacrificial anode 21 becomes thinner (see FIG. 4). For this reason, as the pressure loss caused by the sacrificial anode 21 decreases, the flow rate in the pipe 12 at a predetermined pump rotational speed increases. That is, even at the same pump rotational speed as when the amount of melting of the sacrificial anode 21 is small, the flow rate in the pipe 12 increases due to the decrease in pressure loss caused by the increase in the amount of melting of the sacrificial anode 21. Therefore, the amount of melting of the sacrificial anode 21, that is, the exchange timing can be determined based on the change amount of the detected values of both pressure sensors 15 and 16.

[0022] The ECU 18 has previously measured in advance the relationship between the cross-sectional area of the sacrificial anode 21 [m 2 and the differential pressure (P2 - P1) [kPa] obtained by learning the pressure loss characteristics corresponding to the pump rotational speed when the pump 14 is operated at the same pump rotational speed, that is, a characteristic curve so-called P-Q curve (see FIGS. 5 and 6) is stored.

[0023] FIG. 5 is a characteristic diagram showing the relationship between the cross-sectional area of the sacrificial anode and the differential pressure during water supply. The pump rotation speed A [rpm] during water supply is constant. As shown in FIG. 5, the characteristic line La shows that as the cross-sectional area of the sacrificial anode 21 decreases, the differential pressure (P2 - P1), that is, the pressure loss decreases. When the pressure loss drops below the specified value Pa from the characteristic line La, the ECU 18 prompts the user to replace the sacrificial anode 21. The user replaces the sacrificial anode unit 20.

[0024] FIG. 6 is a characteristic diagram showing the relationship between the cross-sectional area of the sacrificial anode and the differential pressure during drainage. The pump rotation speed B [rpm] during drainage is constant. As shown in FIG. 6, it shows that as the cross-sectional area of the sacrificial anode 21 decreases, the differential pressure (P2 - P1), that is, the pressure loss decreases. When the pressure loss drops below the specified value Pb from the characteristic line Lb, the ECU 18 prompts the user to replace the sacrificial anode 21. The user replaces the sacrificial anode unit 20.

[0025] (Replacement of the sacrificial anode unit 20) Remove all the bolts 27 that fix the sacrificial anode unit 20 to the second pipe section 12B, take out the sacrificial anode unit 20 from the second pipe section 12B, and then attach a new sacrificial anode unit 20 to the pipe 12 with the bolts 27. Thereby, the replacement of the sacrificial anode 21 can be easily performed.

[0026] (Operation and effects of Embodiment 1) According to the present embodiment, based on the difference between the detection value of the first pressure sensor 15 that detects the pressure in the first pipe section 12A connecting the pump 14 and the seawater supply target 32 and the detection value of the second pressure sensor 16 that detects the pressure in the second pipe section 12B connecting the pump 14 and the sea 30, the dissolved state (consumed state) of the sacrificial anode 21 is grasped. Thereby, the replacement timing of the sacrificial anode 21 can be determined. As a result, by replacing the sacrificial anode 21 at the optimum timing, corrosion prevention can be continued without interrupting the electrons of the sacrificial anode 21.

[0027] In addition, based on the decrease in the cross-sectional area of the sacrificial anode 21, when the differential pressure between the detected value of the first pressure sensor 15 and the detected value of the second pressure sensor 16 is equal to or greater than a specified value, it is determined as the replacement timing of the sacrificial anode 21, so that the replacement timing of the sacrificial anode 21 can be accurately determined.

[0028] [Other Embodiments] The technology disclosed in this specification is not limited to the above-described embodiments and can be implemented in various other forms. For example, the technology disclosed in this specification may be applied as the cathodic protection device 10 for the pipe 12 used in structures installed at sea or in the sea, such as floating offshore wind power generation devices, wave power generation devices, ships for maritime transportation, and the like. Further, the support fitting 22 and the pedestal 23 may be joined not only by welding but also by bolts. Further, the pump 14 may be replaced with a dedicated water supply pump and a dedicated drainage pump.

Description of Reference Numerals

[0029] 10 Cathodic protection device 12 Pipe 12A First pipe section 12B Second pipe section 14 Pump 15 First pressure sensor 16 Second pressure sensor 18 ECU (Electronic Control Unit) 18a Replacement timing determination unit 20 Sacrificial anode unit 21 Sacrificial anode 22 Support fitting 23 Pedestal 30 Sea 32 Seawater supply target

Claims

1. An impressed current cathodic protection device for preventing corrosion of the inner surface of a pipe connecting the sea and a seawater supply target, comprising: a pump provided in the pipe for supplying and discharging seawater to and from the seawater supply target; a first pressure sensor for detecting the pressure in a first pipe section of the pipe that connects the pump and the seawater supply target; a second pressure sensor for detecting the pressure in a second pipe section of the pipe that connects the pump and the sea; a sacrificial anode disposed in the second pipe section; an exchange timing determination unit for determining the replacement timing of the sacrificial anode based on the differential pressure between the detection value of the first pressure sensor and the detection value of the second pressure sensor; An impressed current cathodic protection device comprising the above components.

2. The impressed current cathodic protection device according to Claim 1, wherein: the exchange timing determination unit determines the replacement timing of the sacrificial anode when the differential pressure between the detection value of the first pressure sensor and the detection value of the second pressure sensor is equal to or greater than a predetermined value based on the decrease in the cross-sectional area of the sacrificial anode.

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