KR101174643B1 - The predicting controlled cathodic protection system for reducing electromagnetic signature - Google Patents

Abstract

PURPOSE: A prediction controlled cathodic protection system for reducing an electromagnetic field in a ship is provided to control a current absorbing unit for grounding a propeller shaft to absorb a ground current by predicting an amount of protective currents. CONSTITUTION: An external power type protection control unit(130) controls an amount of protective currents according to a potential of a reference electrode detected by a potential detection unit(131). A propeller shaft potential detection unit(220) detects a propeller shaft potential. A current absorbing unit(230) for grounding a propeller shaft absorbs a shaft current to flow in the ship. A first communication unit transmits the protective current from the potential of the reference electrode. A second communication unit is connected to an active shaft grounding control unit and receives information from the first communication unit.

Description

Predictive corrosion control system for reducing the electromagnetic field of ships {THE PREDICTING CONTROLLED CATHODIC PROTECTION SYSTEM FOR REDUCING ELECTROMAGNETIC SIGNATURE}

According to the present invention, a ship having a multi-zone controlled externally powered control device and an active shaft grounding control device predicts an amount of anticorrosive current to be emitted from an externally powered control device and predicts the potential difference in advance in the active shaft grounding control device. The present invention relates to a predictive controlled corrosion protection system for reducing the electromagnetic field of the propeller shaft, which controls the current absorbing means for grounding the propeller shaft.

Vessels operate in various routes and operating conditions and are highly at risk of corrosion and require a long life span of 20 years or more from the viewpoint of safety risks, construction costs, and scale. Do.

In general, ships that do not have anti-corrosion measures are reported to have about 1 mm of corrosion per year.However, if proper anti-corrosion measures are established, corrosion of less than 1 um per year may occur. Damage can be minimized.

The main causes of corrosion in ships include atmospheric corrosion with salt, corrosion by seawater, erosion by ship speed, cavitation due to rotation of propellers or pump impellers, and corrosion fatigue due to constant fatigue of the hull.

 Corrosion preventing devices for preventing corrosion of such vessels will be described.

In order to prevent hull corrosion, the first method is generally applied by painting corrosion resistant paint on the bottom surface, but this method causes corrosion of hull due to local paint damage caused by the operation of the ship. In general, the hull of a ship is a potential condition where corrosion does not occur at the surface of the hull through a sacrificial anode corrosion protection device that protects the hull by artificially attaching metals having a lower galvanic potential than the hull, and a non-consumable anode and reference electrode. An external power corrosion protection device is always used.

-Sacrificial Bipolar Corrosion Prevention Device

Sacrificial bipolar corrosion protection is a device that attaches metals with lower galvanic potential (zinc, magnesium, aluminum) to the hull surface below the surface of the water, causing these metals to corrode before the steel hull. When a metal with a lower potential than the hull is attached to the hull, the hull and the propeller become the cathode, and the metals attached to the hull become the anode, so that the hull is protected prior to the hull.

-External power corrosion protection device

Externally powered corrosion protection device is an ICCP (Impressed current cathodic protection) as a device that protects the hull from corrosion by artificially generating current to maintain the potential of the hull surface at a constant potential that does not cause corrosion as shown in FIG. Using the Ag-AgCl electrode as the reference electrode, the hull potential was measured to be about -0.6 V and about -0.24 V for the bronze propeller. Maintaining the hull potential near -0.8 V by applying an appropriate corrosion protection current to the hull surface can keep the hull surface in an inimitable area where corrosion does not occur.

If the hull surface potential is lowered further, it may have a better effect in terms of corrosion protection, but this has the disadvantage of causing premature damage to the hull surface paint, which is based on a potential of about -0.8 V on most vessels around the world. have.

In the case of sacrificial anode corrosion protection devices, the sacrificial anodes are gradually consumed over time, so regular maintenance and replacement is essential at the time of the ship's opening.However, externally powered corrosion protection devices may be used for non-consumable metal anodes, reference electrodes and power supplies. The initial installation cost increases by using the sacrificial anode corrosion protection device, but the maintenance cost is reduced, most ships have recently been installed externally powered corrosion protection device.

As a conventional technique related to an externally powered corrosion prevention device, Korean Patent No. 10-1066104 proposed by the present applicant "Electrical system of network-based offshore structure" (registered on September 9, 2011) and Korean Patent No. 10-0488580 "Hull Electricity Systems" (registered May 2, 2005) has been published.

On the other hand, a hull made of ferromagnetic material generates various electromagnetic fields according to "Hull Electromagnetic Signal Source and Reduction Measures" (Jung Hyun Joo, Chang Sup Yang, National Institute of Defense Science, 2003 Summer Conference of the Korean Institute of Electrical Engineers). It is a big obstacle to the implementation of the function. Especially, the hull corrosion prevention system and the propeller of the hull cause AC and static magnetic field, AC electric field and electrostatic field signals.

In order to solve this problem, a multi-zone controlled cathodic protection system that controls the corrosion current by dividing the area by installing a large number of anodes of ICCP, and active in grounding between propeller shaft and hull Active Shaft Grounding System is used to realize the minimum resistance between the two ends through control.

In the multi-zone controlled anti-corrosion device, as shown in FIG. 2A, since the anode has to supply current to a far-off object, the current density is not uniform throughout, and the anode voltage is relatively low. It is not suitable for the implementation of the ship's airtight (Stealth) function, but in the case of a multi-zone corrosion prevention device as shown in Figure 2 (B), if a large number of anodes are divided into areas to cover a small area, (A) In the case of a single zone, the total mode current is 230A, so the overall mode current can be reduced to 200A, as in the multiple zone of (B), and the anode voltage can be reduced, so it is easy to realize the ship's tightness. Do.

On the other hand, when the propeller rotates through the ship's main engine (main engine), a very low constant current is generated, and this constant current causes a potential difference between the propeller shaft and the hull, causing the propeller shaft to corrode.

In order to solve this problem, ships are operating a propeller shaft equipped with passive shaft grounding that suppresses propeller shaft corrosion and alternating electromagnetic fields by grounding the shaft and hull through slip rings and brushes. . However, the passive shaft grounding device requires periodic maintenance of the slip ring assembly and the brush, and may not be a complete suppression measure because it may generate local shaft corrosion or alternating electromagnetic signal when the performance is degraded. In addition, even in the case of a passive shaft grounding device in a steady state, the resistance between the shaft and the hull is about 1 mΩ, which prevents complete grounding.

To solve this problem, the potential between the shaft and the hull is measured in real time through a separate slip ring, and if the resistance (or potential) between the shaft and the hull increases rapidly, a separate slip ring and power supply are used to force the shaft through the shaft. An active shaft grounding device has been developed and used to prevent corrosion of the shaft and to suppress alternating electromagnetic fields by absorbing the flowing corrosion current. Using this device, the resistance between the shaft and the hull can be reduced to about 10uΩ, allowing almost complete grounding.

Conventional techniques for active shaft grounding of hulls include UK PATENT GB 2377037 "Active Shaft Grounding System for ELF signature" (published Apr. 9, 2003), Canadian Patent No. 906,054 "Controlled Potential Ship Grounding System" (published Jul. 25, 1972) has been proposed.

4 is a conceptual diagram of an active shaft grounding control system, which includes propeller shaft potential difference detecting means for detecting a potential difference between a propeller shaft and a hull of a ship, and a current for propeller shaft grounding (also referred to as a corrosion current) through a circuit including a propeller shaft; Active shaft ground control unit for controlling the current absorbing means for propeller shaft grounding so that the potential difference between the propeller shaft and the hull is minimized according to the potential difference detected by the propeller shaft potential difference detecting means. Is made of.

On the other hand, the most effective and intimidating weapons for ships used for military purposes are mines and torpedoes.

Up to now, the main sensitive mines in the world have used magnetic and magnetic sensors to detect the electrostatic field signals generated by the ferromagnetic material of the ship as well as acoustic and pressure sensors. However, due to the continuous improvement of trap countermeasures against existing mines (elements, demagnetization, low noise, non-magnetic, etc.) and the development of the minescaping ability of anti-destructive ships, due to the response of electrostatic fields and acoustic signals generated from the ships in recent years The new mines of the compound sensitive method are developed to escape the detonation method and to respond to signals such as electrostatic and alternating electromagnetic fields emitted from the ship.

There is a need to increase ship survivability for these new response mines.

In particular, countermeasures are required to reduce AC field signals caused by hull corrosion and corrosion protection devices and by trap equipment.

In order to minimize the alternating and static magnetic fields and alternating and electrostatic fields generated by the ships, a multi-zone controlled external power corrosion prevention device and an active shaft grounding system are installed to minimize the current. This affects the propeller shaft potential difference.

 This minimizes the resistance between the shaft and the hull by absorbing the shaft current through the operation of the active shaft grounding system, but this is because the propeller shaft is momentarily increased because the system is operated after recognizing it after raising the shaft potential. Due to the modulation of the anti-corrosion current due to the rotation, a shaft rate ELFE signal up to several tens of Hz can be generated.

Accordingly, in this patent, when anticorrosive current is output from the external power corrosion prevention device in order to prevent the increase of the shaft potential, the AC and static magnetic fields are generated by absorbing the shaft current through communication with the active shaft grounding system in advance. To prevent this, we want to implement a more stable ship's seal function.

Registered Korean Patent No. 10-1066104 "Electrical system of offshore structure based on network" (Registered on September 9, 2011) Korea Patent Registration No. 10-0488580 "Hull Electricity System" (registered May 2, 2005) UK UK PATENT GB 2377037 "Active Shaft Grounding System for ELF signature" (published Apr 9, 2003) Canadian Canadian Patent No. 906,054 "Controlled Potential Ship Grounding System" (published Jul 25, 1972)

The present invention has been made in order to solve the problems of the prior art as described above, in particular for the purpose of preventing the occurrence of alternating current and static magnetic field due to the propeller shaft potential is increased due to the anticorrosive current emitted from the external power type control device. do.

In order to solve the above problems, the present invention, the anti-corrosion anode mounted on the hull shell plate for emitting anti-corrosive current; A reference electrode mounted on the hull shell to detect whether the hull is protected; An external power type controller configured to include a potential detector configured to receive a potential value of the reference electrode, and control an amount of the corrosion current output to the anode for the method according to the potential value of the reference electrode detected by the potential detector; Propeller shaft potential difference detection means for detecting a propeller shaft potential difference, which is a potential difference between the propeller shaft and the hull of a ship; Propeller shaft ground current absorbing means for absorbing the axial current through the circuit including the propeller shaft to flow to the hull; An active shaft ground control unit for controlling the amount of ground current absorbed by the propeller shaft ground current absorbing means according to the propeller shaft potential difference sensed by the propeller shaft potential difference detecting means so as to minimize the propeller shaft potential difference; First communication means connected to the external power type control unit for transmitting the method current value to be calculated by the external power type control unit from the potential value of the reference electrode inputted by the potential detection unit; Second communication means connected to the active shaft ground control means to receive information transmitted by the first communication means; The active shaft grounding control unit comprises: controlling the propeller shaft grounding current absorbing means according to the propeller shaft potential difference and an output current value transmitted to the second communication means; .

In the above, the active shaft ground control unit obtains a predicted potential difference predicted by the propeller shaft potential difference detecting means from the outputted anticorrosive current value, and the propeller according to the maximum value of the propeller shaft potential difference and the predicted potential difference. By controlling the current absorbing means for shaft grounding, it is possible to prevent the propeller shaft potential difference from increasing.

The method of claim 2, wherein the anti-corrosion anode is provided in a plurality of hull shell plate, the reference electrode is provided in a plurality of hull shell plate, the external power-type control unit, in a region in which a plurality of anti-corrosion anode and a plurality of reference electrodes are installed. Therefore, grouping into a plurality of groups, it characterized in that for each group to control the amount of the corrosion current output to the anode for the method according to the potential value of the reference electrode.

As described above, the present invention, in a ship provided with a multi-zone controlled externally powered control device and an active shaft ground control device, in advance in the active shaft ground control device by predicting the amount of the anticorrosive current to be emitted from the externally powered control device According to the predicted potential difference, the propeller shaft ground current absorbing means provides a predictive control electromagnetic field reduction system which controls the output current for grounding.

Accordingly, the potential between the propeller (or propeller shaft) and the hull of the ship can be stabilized to reduce the electromagnetic field generated from the hull, and in particular, it is possible to improve the ability to evade the atmosphere of the ship.

1 is a block diagram of a system according to an embodiment of the present invention;
2 (A) is a single zone control hull corrosion protection device, (B) is a conceptual diagram of a multi-zone control hull corrosion protection device according to an embodiment of the present invention,
3 is a conceptual diagram of a conventional externally powered control device;
4 is a conceptual diagram of a conventional active shaft grounding control device.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention in the drawings, portions not related to the description are omitted, and like reference numerals are given to similar portions throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

Conventional techniques relating to an externally powered control device and an active shaft grounding control device are considered herein and incorporated hereinbefore and hereinafter with respect to conventional techniques relating to an externally powered control device and an active shaft grounding control device. Although the description is omitted, it should be understood that the general technical description of the externally powered control device and the active shaft grounding control device is included in the present specification.

1 is a block diagram of a system according to the present invention.

The system is largely composed of a multi-zone controlled externally powered control device 100 and an active shaft ground control device 200.

The multi-zone controlled externally-powered control device 100 includes a reference electrode 110, a positive electrode 120 for an anticorrosion method, an externally-powered controller 130, and a first communication means 140.

In addition, the external power type control unit 130 is composed of the potential detector 131, the central controller 132, the output controller 133, and the rectifier 134.

The reference electrode 110 is mounted on the hull outer plate (mounted insulated from the hull outer plate) to detect whether the hull is protected.

The potential detector 131 receives an analog potential value of the reference electrode 110, converts it into a digital value, and outputs the digital potential value to the central controller 132.

The central controller 132 determines the amount of anticorrosive current to be output to the anticorrosive anode 120 according to the electric potential value of the reference electrode input from the electric potential detector 131.

In addition, the central controller 132 transmits the method current value calculated by the central controller 132 from the potential value of the reference electrode input from the potential detector 131 through the first communication means 140 to the second communication means 210. )

On the other hand, the power supply unit 135 generates AC power and outputs it to the rectifying unit 134, and the rectifying unit 134 converts AC power to DC power and outputs it to the output control unit 133.

The output controller 133 controls the amount of anticorrosive current output to the anticorrosive anode 120 under the control of the central controller 132.

In the above configuration, the configuration of the reference electrode 110, the potential detection unit 131, the central control unit 132, the output control unit 133, the power supply unit 135, the rectifying unit 134, and the output control unit 133 is general. This can be said to be similar to the configuration of an externally powered control device.

The active shaft grounding control device 200 largely includes a second communication means 210, a propeller shaft potential difference detecting means 220, a current absorbing means 230 for propeller shaft grounding, and an active shaft ground controller 240.

The propeller shaft potential difference detecting means 220 detects a propeller shaft potential difference, which is a potential difference between the propeller shaft of the ship and the hull.

The propeller shaft ground current absorbing means 230 absorbs current by applying a negative potential to absorb the ground current through a circuit including the propeller shaft.

The conventional active shaft grounding control unit 240 controls the amount of grounding current supplied from the propeller shaft grounding current absorbing means 230 to minimize the propeller shaft potential difference, which is detected by the propeller shaft potential difference detecting means 220. According to one propeller shaft potential difference, the current absorbing means 230 for propeller shaft grounding is controlled.

According to the present invention, the second communication means 210 is connected to the active shaft ground control unit 240, and the second communication means 210 is the first communication means 140 of the multi-zone control type externally powered control device 100. Input method current value from).

The first communication means 140 and the second communication means 210 may be connected using a communication protocol such as RS485, RS422, MODBUS, Ethernet, and the like.

The active shaft ground control unit 240 obtains the predicted potential difference of the propeller shaft through the value of the scheme current to be output, which is transmitted to the second communication unit 210.

The predicted potential difference is a potential difference predicted to be detected by the propeller shaft potential difference detecting means according to the anticorrosive current value calculated by the multi-zone controlled externally-powered control device to emit through the positive electrode for the electrode due to the potential value of the reference electrode. it means.

In a ship equipped with a conventional externally powered control device and an active shaft grounding control device, the externally powered control device emits the anticorrosive current according to the potential value of the reference electrode, and the propeller shaft potential difference detecting means is caused by the emitted current. The propeller shaft potential difference detected is changed, and according to the detected propeller shaft potential difference, it is common for the active shaft grounding control unit to control the amount of grounding current supplied from the current absorbing means for propeller shaft grounding. The sudden fluctuations of the E will occur, which means that a sudden electromagnetic field signal will be generated from the ship.

On the other hand, in this embodiment, the multi-zone control type control device obtains the corresponding method current value to be output from the potential value of the reference electrode, and transmits the output method current value to the active axis grounding control device, and active axis grounding control. The device obtains the predicted potential difference based on the received method current value and controls the current absorbing means for propeller shaft grounding according to the maximum value of the predicted potential difference and the propeller shaft potential difference currently detected so that the potential difference between the propeller shaft and the hull shell of the ship is always It is intended to stay in a very small range.

The prediction potential difference may be configured in advance with a prediction potential difference information database in which prediction potential difference information corresponding to each output current value is stored, or a prediction potential difference calculation module capable of calculating the prediction potential difference from the output current value is provided. Can be obtained.

In this way, the predicted potential difference of the propeller shaft is calculated before outputting the anticorrosive current emitted from the multi-zone-controlled externally-powered control device, and the active shaft grounding control unit absorbs the current for the propeller shaft grounding in advance. The potential difference with can be minimized.

In addition, according to the present embodiment, as shown in FIG. 2B, a plurality of anticorrosive anodes and reference electrodes are provided on the hull outer plate, and the external power type control unit 130 is provided in a region in which a plurality of anticorrosive anodes and a plurality of reference electrodes are installed. Therefore, grouping into a plurality of groups, it is possible to control the amount of the anticorrosive current output to the positive electrode for the method according to the potential value of the reference electrode for each group.

In the case of providing one anticorrosive anode in one vessel in the prior art, the amount of anticorrosive current consumed increases, thereby increasing the capacity of the system, and it is not only difficult to apply a uniform anticorrosive current to the entire hull shell, but also to emit There is a problem that the magnitude of the anticorrosive current increases.

In addition, even when a plurality of anticorrosive anodes are provided in a ship, when the anticorrosive current is discharged by one reference electrode, since the same magnitude of current is emitted from each of the anticorrosive anodes, more anticorrosive currents are emitted than necessary, resulting in waste of energy. Will result.

In addition, the increase of the anticorrosive current emitted in the water acts as a factor to increase the electromagnetic field signal underwater, which causes the risk of being easily exposed to the torpedo or mine target.

Therefore, the present embodiment divides one vessel, that is, the object to be divided into several zones, to control the anti-corrosive current emitted from the corresponding zone according to the potential value detected at each reference electrode. This embodiment not only solves the problem of conventional over-current discharge, but also can increase the efficiency of corrosion protection and can also reduce the electromagnetic field generated in the hull.

In addition, when a plurality of reference electrodes are provided as described above, the method current values transmitted by the multi-zone-controlled externally-powered control device to the active shaft grounding control device transmit or output all of the method current values to be output for each zone. The sum of all the scheme currents to be calculated may be transmitted or multiplied by the weight factor of each scheme current value, and then the average value thereof may be transmitted.

In addition, the active shaft ground control unit obtains a predicted potential value from all the method currents, receives a predicted potential value from the sum of all method currents, or predicts the potential from the average value of the method current values calculated by the weight factor. You can get the value.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the embodiments described above are intended to be illustrative, but not limiting, in all respects. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

110: reference electrode 120: anticorrosive anode
130: external power type control unit 131: potential detection unit
132: central control unit 133: output control unit
134: rectifier 135: power supply
140: first communication means
200: active shaft ground control device 210: second communication means
220: propeller shaft potential difference detection means
230: current absorbing means for propeller shaft grounding
240: active shaft ground control unit

Claims (3)

Anti-corrosion anode mounted on the hull shell to discharge anti-corrosive current;
A reference electrode mounted on the hull shell to detect whether the hull is protected;
An external power type controller configured to include a potential detector configured to receive a potential value of the reference electrode, and control an amount of the corrosion current output to the anode for the method according to the potential value of the reference electrode detected by the potential detector;
Propeller shaft potential difference detection means for detecting a propeller shaft potential difference, which is a potential difference between the propeller shaft and the hull of a ship;
Propeller shaft ground current absorbing means for absorbing the axial current through the circuit including the propeller shaft to flow to the hull;
An active shaft ground control unit for controlling the amount of ground current absorbed by the propeller shaft ground current absorbing means according to the propeller shaft potential difference sensed by the propeller shaft potential difference detecting means so as to minimize the propeller shaft potential difference;
First communication means connected to the external power type control unit for transmitting the method current value to be calculated by the external power type control unit from the potential value of the reference electrode inputted by the potential detection unit;
Second communication means connected to the active shaft ground control means to receive information transmitted by the first communication means;
, ≪ / RTI >
The active shaft grounding control unit controls the current absorbing means for grounding the propeller shaft according to the propeller shaft potential difference and an output method current value transmitted to the second communication means;
Predictive corrosion protection system for reducing hull electromagnetic fields.
The method of claim 1,
The active shaft grounding control unit obtains a predicted potential difference predicted by the propeller shaft potential difference detecting means from the outputted anticorrosive current value, and the propeller shaft ground current according to the maximum value of the propeller shaft potential difference and the predicted potential difference. A predictive controlled corrosion protection system for reducing hull electromagnetic fields, characterized in that it controls the absorbing means.
The method of claim 1,
The anti-corrosion anode is provided in plurality in the hull shell plate, the reference electrode is provided in a plurality of hull shell plate,
The externally-powered type control unit groups a plurality of anti-corrosion anodes and a plurality of reference electrodes into a plurality of groups according to the installed area, and outputs the anti-corrosion current to the anti-electrode according to the potential value of the reference electrode for each group. Predictive control corrosion protection system for reducing the electromagnetic field of the hull, characterized in that for controlling the.

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