Auxiliary anode assembly and impressed current cathodic protection system

Abstract

This invention provides an auxiliary anode assembly, including a housing, an auxiliary anode body disposed within the housing, and a cable. The housing is a sealed structure with a water inlet at the top for seawater to enter and be stored within it. The bottom of the housing has multiple micropores, allowing seawater to contact the sediment below the housing, enabling the auxiliary anode body to be electrically connected to the sediment through the seawater. The micropores also prevent sediment from entering the housing. This auxiliary anode assembly maintains normal operation even when the tide level is low and the anode is exposed above the sea surface, making it suitable for use in shallow marine environments such as tidal zones and mudflats. Furthermore, it reduces or eliminates contact between the auxiliary anode body and sediment, thereby extending the lifespan of the auxiliary anode body. This invention also provides an impressed current cathodic protection system.

Description

Technical Field

[0001] This invention relates to the field of cathodic protection and corrosion prevention technology, and in particular to an auxiliary anode assembly and an impressed current cathodic protection system. Background Technology

[0002] With the development and utilization of marine resources, more and more offshore facilities have been built and put into operation. However, due to the special nature of the marine environment, commonly used steel equipment generally faces harsh corrosive conditions. To ensure the safety of these facilities, existing marine engineering projects typically employ anti-corrosion measures such as anti-corrosion coatings and cathodic protection. Among these, anti-corrosion coatings are currently the most widely used anti-corrosion technology. However, these coatings are prone to damage during equipment installation, and when they are damaged or peel off, the workload for repainting, electroplating, and other maintenance of the metal structures below sea level is substantial. Furthermore, their anti-corrosion performance gradually deteriorates over time. Therefore, cathodic protection must be used in conjunction with these measures for comprehensive protection.

[0003] Cathodic protection is mainly divided into two methods: sacrificial anode and impressed current. Sacrificial anodes require one-time design and installation based on the equipment's design life, resulting in a large number of anodes and high initial investment costs. Impressed current systems, on the other hand, are simpler to install and lower in cost, and are currently widely used in offshore wind power and other marine engineering facilities. However, the application of either impressed current protection technology in shallow waters is limited. This is because, in nearshore shallow waters, due to tidal changes, fixed auxiliary anodes may be exposed to the atmosphere (i.e., when the tide recedes and the water level drops, the auxiliary anodes may not be able to be submerged in seawater and will be exposed to the atmosphere), causing the original impressed current system to fail due to a circuit break. Furthermore, when auxiliary anodes are buried by silt, they usually fail relatively quickly, and fixed impressed current systems are difficult to repair once damaged; even if repair is possible, the installation work is difficult and costly. Summary of the Invention

[0004] The purpose of this invention is to provide an auxiliary anode assembly that can still function normally when the tide level is low and the anode is exposed above the sea surface, enabling it to be used in shallow marine environments such as tidal zones and muddy areas. Furthermore, it can reduce or avoid contact between the auxiliary anode body and sediment, thereby extending the service life of the auxiliary anode body.

[0005] This invention provides an auxiliary anode assembly for an impressed current cathodic protection system. The auxiliary anode assembly includes a housing, an auxiliary anode body disposed within the housing, and a cable. One end of the cable is located inside the housing and electrically connected to the auxiliary anode body, while the other end of the cable extends outside the housing and is used for electrical connection to a potentiostat. The housing is a sealed structure, with a water inlet at the top for allowing seawater to enter and be stored within it. The bottom of the housing has multiple micropores, allowing the seawater inside to contact the sediment below the housing through these micropores, enabling the auxiliary anode body to be electrically connected to the sediment below the housing via the seawater. The micropores also prevent sediment from entering the housing.

[0006] Furthermore, the pore size of the micropore is 0.01 mm to 0.25 mm.

[0007] Furthermore, the housing includes a top plate, a protective cover, and a bottom plate. The protective cover has a cylindrical structure and openings at both the top and bottom. The top plate is connected to the top opening of the protective cover, and the bottom plate is connected to the bottom opening of the protective cover. The top plate, the protective cover, and the bottom plate form a receiving cavity, and the auxiliary anode body is disposed within the receiving cavity. The water inlet is disposed on the top plate, and the micropores are disposed on the bottom plate.

[0008] Furthermore, the auxiliary anode body is spaced apart from the base plate, and the auxiliary anode body is suspended within the housing.

[0009] Furthermore, the sidewalls of the protective cover are inclined surfaces that slope outwards from top to bottom, so that the protective cover as a whole has a conical structure; the size of the bottom plate is larger than the size of the top plate.

[0010] Furthermore, the base plate includes multiple filter plates stacked vertically, and each of the multiple filter plates is provided with the micropores; in every two adjacent base plates, the diameter of the micropores on the lower base plate is smaller than the diameter of the micropores on the upper base plate.

[0011] Furthermore, the density of the bottom plate is less than that of seawater to prevent the shell from sinking into the mud and sand.

[0012] Furthermore, the protective cover is made of metal and has a sacrificial anode.

[0013] The present invention also provides an impressed current cathodic protection system, including the above-mentioned auxiliary anode assembly, composite electrode sensor and potentiostat, wherein the auxiliary anode assembly is disposed near the protected object, the composite electrode sensor is disposed on the protected object, the composite electrode sensor includes a reference electrode for measuring the potential of the protected object, the reference electrode is electrically connected to the potentiostat, and the auxiliary anode body is electrically connected to the potentiostat via the cable.

[0014] Furthermore, the composite electrode sensor also includes a base, a seawater flow velocity measuring device, and a pressure sensor. The reference electrode, the seawater flow velocity measuring device, and the pressure sensor are all disposed on the base. The pressure sensor is disposed above the seawater flow velocity measuring device, and both the seawater flow velocity measuring device and the pressure sensor are electrically connected to the potentiostat.

[0015] The auxiliary anode assembly provided by this invention, by placing the auxiliary anode body inside a sealed housing, serves two purposes: firstly, the housing protects the auxiliary anode body from impacts and erosion by sediment / water flow; secondly, it reduces or avoids direct contact between sediment and the auxiliary anode body, thereby extending its service life. Simultaneously, a water inlet is provided at the top of the housing, allowing external seawater to enter and be stored within. Furthermore, multiple micropores are provided at the bottom of the housing, enabling the seawater inside to contact the sediment below, thus allowing the auxiliary anode body to be electrically connected to the sediment. Therefore, even when the tide has completely receded and the auxiliary anode assembly is exposed on the seabed, the electric field lines of the auxiliary anode body can still connect with the protected body through the seawater and sediment, providing continuous cathodic protection. This allows the assembly to be used in shallow marine environments such as tidal zones and muddy areas. Moreover, the micropores allow seawater to pass through, ensuring that the seawater inside the shell is connected to the bottom sediment and that the seawater does not flow out quickly. At the same time, the sediment cannot enter the shell through the micropores, thereby reducing or preventing the sediment from entering the shell and coming into contact with the auxiliary anode body. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the auxiliary anode assembly in an embodiment of the present invention.

[0017] Figure 2 for Figure 1 A bottom view.

[0018] Figure 3 for Figure 2 A schematic diagram of the structure after removing the base plate.

[0019] Figure 4 for Figure 1 A cross-sectional schematic diagram.

[0020] Figure 5 This is a partial cross-sectional schematic diagram of the base plate in an embodiment of the present invention.

[0021] Figure 6 This is a schematic diagram of the impressed current cathodic protection system in an embodiment of the present invention.

[0022] Figure 7 This is a schematic diagram of the circuit structure of the impressed current cathodic protection system in an embodiment of the present invention.

[0023] Figure 8 This is a schematic diagram of the composite electrode sensor in an embodiment of the present invention.

[0024] Figure 9 This is a schematic diagram of the structure of an impressed current cathodic protection system in another embodiment of the present invention. Detailed Implementation

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0027] The directional terms such as "up," "down," "left," "right," "front," "back," "top," and "bottom" (if present) used in the specification and claims of this invention are defined by the position of the structures in the drawings and the relative positions of the structures, and are only for the clarity and convenience of expressing the technical solution. It should be understood that the use of directional terms should not limit the scope of protection claimed in this application.

[0028] like Figures 1 to 6 As shown, the auxiliary anode assembly 1 provided in this embodiment of the invention is used in an impressed current cathodic protection system. The auxiliary anode assembly 1 includes a housing 11, an auxiliary anode body 12 disposed within the housing 11, and a cable 13 (wherein, Figures 1 to 4Cable 13 (not shown) is located inside the housing 11 and electrically connected to the auxiliary anode body 12. The other end of cable 13 extends out of the housing 11 and is used for electrical connection to the potentiostat 2. The housing 11 is a sealed structure. The top of the housing 11 has multiple water inlet holes 1110, which allow seawater to enter and be stored inside the housing 11. At the same time, the gas generated during the operation of the auxiliary anode body 12 can be smoothly discharged through the water inlet holes 1110. The bottom of the housing 11 has multiple micropores 1130, through which the seawater inside the housing 11 can contact the sediment below the housing 11 (i.e., the auxiliary anode assembly 1 is located on the seabed, and the seawater inside the housing 11 contacts the sediment on the seabed through the micropores 1130), so that the auxiliary anode body 12 can be electrically connected to the sediment below the housing 11 through the seawater inside the housing 11. The micropores 1130 can prevent sediment from entering the housing 11.

[0029] Specifically, the auxiliary anode assembly 1 provided in this embodiment, by placing the auxiliary anode body 12 inside the housing 11, which is a sealed structure, can protect the auxiliary anode body 12 on the one hand, preventing it from being smashed or washed by mud / water flow, and on the other hand, reduce or avoid direct contact between mud and sand and the auxiliary anode body 12, thereby extending the service life of the auxiliary anode body 12. Meanwhile, by providing a water inlet 1110 at the top of the shell 11, external seawater can enter and be stored inside the shell 11 through the water inlet 1110; at the same time, by providing multiple micropores 1130 at the bottom of the shell 11, the seawater inside the shell 11 can contact the mud and sand below the shell 11 through the micropores 1130, so that the auxiliary anode body 12 can be electrically connected to the mud and sand below the shell 11 through the seawater inside the shell 11. Thus, when the external current is applied to protect the protected body 4, even if the tide completely recedes and the auxiliary anode assembly 1 is exposed on the seabed (i.e. exposed to the sea surface), the electric field lines of the auxiliary anode body 12 can still be connected to the protected body 4 through the seawater inside the shell 11 and the mud and sand below the shell 11 to form a path, thereby continuously applying cathodic protection to the protected body 4, so that it can be used in shallow sea environments such as tidal zones and muddy sea areas. Moreover, the micropores 1130 allow seawater to pass through, ensuring that the seawater inside the shell 11 is connected to the bottom sediment and that the seawater does not flow out quickly. At the same time, the sediment cannot enter the shell 11 through the micropores 1130, thereby reducing or preventing the sediment from entering the shell 11 and contacting the auxiliary anode body 12.

[0030] Furthermore, in this embodiment, the pore size of the micropore 1130 is 0.01 mm to 0.25 mm. Within this range, seawater can flow slowly out of the shell 11 through the micropore 1130 (i.e., seawater will not flow out rapidly), while preventing sediment from entering the shell 11 through the micropore 1130. It should be noted that since the water inlet 1110 is located at the top of the shell 11, sediment generally will not enter the shell 11 through the water inlet 1110, so the pore size of the water inlet 1110 can be set to be relatively large. As one embodiment, the pore size of the water inlet 1110 is 0.25 mm to 1 mm.

[0031] Furthermore, such as Figures 1 to 4 As shown, in this embodiment, the housing 11 includes a top plate 111, a protective cover 112, and a bottom plate 113. The protective cover 112 has a cylindrical structure, with openings at both the top and bottom. The top plate 111 is connected to the top opening of the protective cover 112, and the bottom plate 113 is connected to the bottom opening of the protective cover 112. The top plate 111, the protective cover 112, and the bottom plate 113 together form a receiving cavity 110, in which the auxiliary anode body 12 is disposed. A water inlet 1110 is disposed on the top plate 111, and micropores 1130 are disposed on the bottom plate 113.

[0032] Furthermore, such as Figures 1 to 4 As shown, in this embodiment, the auxiliary anode body 12 is located above the base plate 113, with a gap between the auxiliary anode body 12 and the base plate 113, and the auxiliary anode body 12 is suspended within the housing 11. Specifically, during long-term operation, some mud and sand will inevitably enter the housing 11, and this mud and sand will be deposited on the base plate 113; therefore, this embodiment reduces or avoids contact between the auxiliary anode body 12 and the base plate 113 by spacing the auxiliary anode body 12 from the base plate 113 and keeping the auxiliary anode body 12 suspended.

[0033] Furthermore, such as Figures 1 to 4 As shown, in this embodiment, the sidewall of the protective cover 112 is an inclined structure that slopes outward from top to bottom, so that the protective cover 112 is generally conical; the size of the bottom plate 113 is larger than the size of the top plate 111. This arrangement can prevent the auxiliary anode assembly 1 from being dragged by fishing nets (because the sidewall of the protective cover 112 is an inclined structure, it cannot be hooked by fishing nets), and at the same time, it can increase the bottom area of ​​the shell 11 (i.e., the area of ​​the bottom plate 113 is larger), making its center of gravity more stable and able to fit more stably on the seabed. This not only prevents it from tipping over, but also ensures that the seawater inside the shell 11 comes into contact with the mud and sand below the shell 11 through the micropores 1130 on the bottom plate 113, thereby ensuring the stability of operation.

[0034] Furthermore, such as Figures 1 to 4 As shown, in this embodiment, the protective cover 112 has an overall pyramidal structure, with the bottom plate 113 and top plate 111 both being square structures. Of course, in other embodiments, the protective cover 112 can also be a conical structure, with the bottom plate 113 and top plate 111 both being circular structures. Naturally, the protective cover 112, bottom plate 113, and top plate 111 can also have other shapes.

[0035] Furthermore, such as Figure 4 and Figure 5 As shown, in this embodiment, the bottom plate 113 includes multiple filter plates 1131 stacked vertically, each of which has micropores 1130. In each pair of adjacent bottom plates 113, the diameter of the micropores 1130 on the lower bottom plate 113 is smaller than that on the upper bottom plate 113 (i.e., the diameter of the micropores 1130 on the multiple filter plates 1131 decreases from top to bottom). This arrangement not only facilitates the contact between seawater inside the shell 11 and the sediment below the shell 11 through the micropores 1130 on the bottom plate 113, but also further reduces or prevents sediment from entering the shell 11 through the micropores 1130.

[0036] Furthermore, such as Figure 4 and Figure 5 As shown, in this embodiment, the base plate 113 includes two filter plates 1131 stacked vertically. Of course, in other embodiments, the base plate 113 may also include more filter plates 1131 stacked vertically.

[0037] In another embodiment, a filter membrane (not shown) is also provided on the bottom plate 113. The filter membrane covers the micropores 1130 on the bottom plate 113. The filter membrane allows seawater to pass through while blocking sediment (i.e., sediment cannot pass through the filter membrane), thereby further reducing the amount of sediment entering the outer shell 11. The filter membrane can be a semi-permeable membrane, a microporous filter membrane, etc. Preferably, the filter membrane is disposed on the inner wall of the bottom plate 113 to extend its service life. In another embodiment, a filter membrane can also be disposed on the inner wall of the top plate 111 to further reduce the amount of sediment or other impurities entering the outer shell 11.

[0038] Furthermore, in this embodiment, the density of the bottom plate 113 is less than that of seawater to prevent the shell 11 from sinking into the silt (i.e., to prevent the auxiliary anode assembly 1 from being buried by the silt). Specifically, after long-term operation, the auxiliary anode assembly 1 will inevitably be partially buried by the silt. However, in order to prevent the auxiliary anode assembly 1 from being completely buried by the silt (if it is completely buried, the silt will enter the shell 11 through the water inlet 1110 at the top), the density of the bottom plate 113 is set to be relatively low, so that the shell 11 is lighter overall, and it can avoid being completely buried in the silt during operation (i.e., reaching a semi-buried state), so that it can maintain stable operation.

[0039] Furthermore, such as Figures 1 to 5 As shown, in this embodiment, the base plate 113 is made of plastic. Sealing portions 115 are provided around the perimeter of the base plate 113. The sealing portions 115 are connected to the outer edge of the base plate 113 (that is, the outer edges of multiple filter plates 1131 are simultaneously connected to the sealing portions 115), and the sealing portions 115 are also connected to the bottom opening of the protective cover 112 to provide a seal and improve structural strength. The cable 13 exits the housing 11 through the sealing portion 115 (of course, the cable 13 can also exit the housing 11 from other locations). The sealing portion 115 can be made of polytetrafluoroethylene (PTFE).

[0040] Furthermore, in this embodiment, the top plate 111 is a filter plate made of PP material.

[0041] Furthermore, in this embodiment, the protective cover 112 is made of metal, and a sacrificial anode (not shown) is provided on the protective cover 112. Due to the harsh seabed environment, if the auxiliary anode body 12 is exposed to seawater, it will be subject to long-term erosion by seabed sediment and water currents, causing damage to the oxide coating on the anode surface and affecting the lifespan of the auxiliary anode body 12; at the same time, there is also the risk of being hit by falling objects in the marine environment and being dragged by fishing nets. To meet the above requirements, the protective cover 112 needs to have a certain strength and toughness. Therefore, the protective cover 112 is set as the above-mentioned conical structure, and the protective cover 112 is made of metal (preferably, the protective cover 112 is made of coated steel). At the same time, a sacrificial anode is welded on the protective cover 112 to provide corrosion protection and counterweight for the protective cover 112.

[0042] Furthermore, such as Figure 3 and Figure 4 As shown, in this embodiment, a bracket 114 is provided inside the housing 11 (in this embodiment, the bracket 114 consists of four support columns). The bracket 114 is made of insulating material. The auxiliary anode body 12 is connected to the inner wall of the housing 11 through the bracket 114 (in this embodiment, the auxiliary anode body 12 is connected to the top plate 111 through the bracket 114; that is, the bracket 114 suspends the auxiliary anode body 12 inside the housing 11), thereby providing support and fixing for the auxiliary anode body 12.

[0043] Furthermore, in this embodiment, the auxiliary anode body 12 is a noble metal oxide anode or a platinum-niobium anode, etc. Since the auxiliary anode body 12 is always in the seawater medium, the anodes can be arranged more compactly, and the number of them used can be reduced (if the auxiliary anode body 12 cannot always be in the seawater medium, the number of auxiliary anode bodies 12 needs to be increased, and each auxiliary anode body 12 needs to be placed in seawater at different depths), thereby reducing the volume and cost of the entire auxiliary anode assembly.

[0044] Furthermore, in this embodiment, cable 13 is an armored seawater-resistant cable to give it good corrosion resistance and a long service life.

[0045] like Figure 1 and Figures 6 to 8 As shown, this embodiment of the invention also provides an impressed current cathodic protection system, including the aforementioned auxiliary anode assembly 1, composite electrode sensor 3, and potentiostat 2. The auxiliary anode assembly 1 is used to be placed near the protected object 4 (the protected object 4 can be marine engineering equipment such as offshore wind power, offshore platforms, and subsea pipelines). The composite electrode sensor 3 is used to be placed on the protected object 4. The composite electrode sensor 3 includes a reference electrode 32, which is used to measure the potential of the protected object 4. The reference electrode 32 is electrically connected to the potentiostat 2. The auxiliary anode body 12 is electrically connected to the potentiostat 2 through a cable 13. The potentiostat 2 is also electrically connected to the protected object 4. The potentiostat 2 converts AC power into DC current. It has a built-in control module. During operation, the potentiostat 2 discharges through the auxiliary anode body 12. A path is formed between the auxiliary anode body 12 and the protected object 4 via seawater / silt, thus providing cathodic protection to the protected object 4. Simultaneously, the potentiostat 2 adjusts its output current based on the potential signal measured by the reference electrode 32 (the specific working process of the potentiostat 2 can be found in existing technology and will not be elaborated here). It should be noted that a certain distance is maintained between the auxiliary anode body 12 and the protected object 4 to ensure a more uniform potential distribution on the surface of the protected object 4.

[0046] Furthermore, such as Figures 6 to 8 As shown, in this embodiment, the composite electrode sensor 3 further includes a base 31, a seawater flow velocity measuring device 33, and a pressure sensor 34. The seawater flow velocity measuring device 33 is used to measure the flow velocity of seawater, and the pressure sensor 34 is used to measure the pressure. The reference electrode 32, the seawater flow velocity measuring device 33, and the pressure sensor 34 are all disposed on the base 31; the pressure sensor 34 is disposed above the seawater flow velocity measuring device 33, and both the seawater flow velocity measuring device 33 and the pressure sensor 34 are electrically connected to the potentiostat 2. The potentiostat 2 can adjust its operating mode according to the seawater flow velocity signal measured by the seawater flow velocity measuring device 33 and the pressure signal measured by the pressure sensor 34. Of course, in other embodiments, if the composite electrode sensor 3 is always located below the sea surface (i.e., not exposed above the sea surface), then the seawater flow velocity measuring device 33 and the pressure sensor 34 are not required.

[0047] Specifically, in this embodiment, the seawater flow velocity measuring device 33 is an impeller-type flow velocity measuring device. The blades of the seawater flow velocity measuring device 33 generate different rotation speeds according to the seawater flow velocity, thereby transmitting different electrical signals. When the measured seawater flow velocity is continuously zero, it indicates that the tide level has reached its lowest point. At this time, the reference electrode 32 may be exposed above the water surface, and the potential test is no longer accurate. At the same time, the protection area of ​​the protected body 4 is reduced (i.e., the area of ​​the part of the protected body 4 located below the sea surface is reduced, and the protection area is also reduced accordingly). At this time, the potentiostat 2 changes the current output mode accordingly (for example, reducing the output current and changing from constant voltage mode to constant current output mode). Meanwhile, in order to enable the composite electrode sensor 3 to adjust the protection current in time when it is exposed above the water surface (the measurement signal of the seawater flow velocity measuring device 33 has a certain lag), a pressure sensor 34 is provided. When the pressure sensor 34 is exposed above the water surface, the pressure value it measures decreases (for example, the measured pressure value decreases to be close to atmospheric pressure), at which time the protection current can be quickly adjusted. When encountering extremely severe weather such as typhoons, if the seawater flow velocity measured by the seawater flow velocity measuring device 33 exceeds the warning value, the user can decide whether to temporarily shut off the power to the potentiostat 2 for safety reasons, based on specific needs. Thus, the potentiostat 2 can adjust the output current according to the signals (including potential signal, flow velocity signal, and pressure signal) from the composite electrode sensor 3 to ensure the stability of the potential on the surface of the protected object 4, and can adjust the power mode according to the flow velocity signal.

[0048] Furthermore, such as Figure 8 As shown, in this embodiment, the reference electrode 32 includes a zinc reference electrode 321 and a silver / silver chloride reference electrode 322. That is, the reference electrode 32 adopts a dual-electrode technology of zinc reference electrode and silver / silver chloride reference electrode, with the detection signal of zinc reference electrode 321 as the main signal and the detection signal of silver / silver chloride reference electrode 322 as the auxiliary signal.

[0049] Furthermore, such as Figure 8 As shown, in this embodiment, the base 31 is a tubular structure, which facilitates the installation and fixing of the reference electrode 32, the seawater flow velocity measuring device 33 and the pressure sensor 34.

[0050] Furthermore, in this embodiment, the composite electrode sensor 3 can be fixedly connected to the cage or other structures on the surface of the protected body 4 using a U-shaped buckle, which facilitates replacement.

[0051] The working principle of this impressed current cathodic protection system is as follows: The auxiliary anode assembly 1 is located on the seabed. The auxiliary anode body 12, the composite electrode sensor 3, and the protected body 4 within the auxiliary anode assembly 1 are all electrically connected to the potentiostat 2. The potentiostat 2 applies a protective current to the auxiliary anode body 12 and the protected body 4. The composite electrode sensor 3 transmits signals (including potential signals, flow rate signals, and pressure signals) to the potentiostat 2. During operation, when the auxiliary anode assembly 1 is below the sea surface, the electric field lines of the auxiliary anode body 12 connect with the protected body 4 through the seawater, thus applying a protective current to the protected body 4. When the auxiliary anode assembly 1 is exposed on the seabed (i.e., above the sea surface), the electric field lines of the auxiliary anode body 12 connect with the protected body 4 through the seawater inside the shell 11 and the sediment below the shell 11, thus continuously applying a protective current to the protected body 4.

[0052] The auxiliary anode assembly 1 and the impressed current cathodic protection system provided in this embodiment of the invention, by setting the auxiliary anode body 12 inside the housing 11, the housing 11 is a sealed structure. On the one hand, the housing 11 can protect the auxiliary anode body 12, and has the function of preventing the auxiliary anode body 12 from being hit or washed by mud / water flow. On the other hand, it can reduce or avoid direct contact between mud and sand and the auxiliary anode body 12, thereby extending the service life of the auxiliary anode body 12. Meanwhile, by providing a water inlet 1110 at the top of the shell 11, external seawater can enter and be stored inside the shell 11 through the water inlet 1110; at the same time, by providing multiple micropores 1130 at the bottom of the shell 11, the seawater inside the shell 11 can contact the mud and sand below the shell 11 through the micropores 1130, so that the auxiliary anode body 12 can be electrically connected to the mud and sand below the shell 11 through the seawater inside the shell 11. Thus, when the external current is applied to protect the protected body 4, even if the tide completely recedes and the auxiliary anode assembly 1 is exposed on the seabed (i.e. exposed to the sea surface), the electric field lines of the auxiliary anode body 12 can still be connected to the protected body 4 through the seawater inside the shell 11 and the mud and sand below the shell 11 to form a path, thereby continuously applying cathodic protection to the protected body 4, so that it can be used in shallow sea environments such as tidal zones and muddy sea areas. Furthermore, the micropores 1130 allow seawater to pass through, ensuring communication between the seawater inside the shell 11 and the bottom sediment, while preventing rapid outflow of seawater. Simultaneously, sediment cannot enter the shell 11 through the micropores 1130, thus reducing or preventing sediment from entering the shell 11 and contacting the auxiliary anode body 12. Meanwhile, the composite electrode sensor 3 used in this invention can collect parameters such as seawater flow velocity, allowing the potentiostat 2 to switch modes promptly, ensuring that the protected structure 4, such as the offshore wind turbine tower, is always under cathodic protection. This invention can be applied to cathodic protection of offshore wind power, submarine pipelines, steel-based bridges, port terminals, and other steel facilities in shallow waters, requiring no welding or backfilling, and is easy to use.

[0053] Example 1

[0054] A certain offshore wind power project is located in nearshore waters, with some wind turbine foundations below the seabed mudline and others in the tidal zone. Using existing impressed current cathodic protection technology, circuit failure can occur due to the auxiliary anode being exposed above sea level. To solve this problem, the aforementioned impressed current cathodic protection system is adopted to protect the wind turbine foundations. Its specific installation structure is as follows... Figure 6 As shown.

[0055] Potentiostat 2 is installed on the wind turbine tower (i.e. Figure 6 The protected body 4 (the equipment storage area inside the wind turbine tower) is connected to the auxiliary anode assembly 1 and the composite electrode sensor 3. The potentiostat 2 converts AC power into DC current, which is discharged through the auxiliary anode body 12 in the auxiliary anode assembly 1. The potentiostat 2 has a built-in control module that can adjust the output current according to parameters such as potential and flow rate.

[0056] The composite electrode sensor 3 is equipped with a flow rate sensor, a pressure sensor, a zinc reference electrode, and a silver / silver chloride reference electrode. It measures the water pressure and flow rate in the area it is in, and also measures the electrode potential of the wind turbine tower for monitoring and control. When the tide is low, the composite electrode sensor 3 is exposed above the water surface, and the measured pressure decreases and the flow rate becomes zero. At this time, the electrode test results are no longer accurate, and the potentiostat 2 automatically switches to constant current mode. Based on the estimated protection area, it reduces the output current to avoid hydrogen embrittlement.

[0057] The offshore wind turbine has a tower diameter of 6m, with a 5m length underwater and inserted into the seabed. The maximum designed protection current is 30A. Four cylindrical metal oxide anodes, each 2.5cm in diameter and 15cm long, are used as auxiliary anodes. The auxiliary anodes are connected to cable 13 via a copper core, with epoxy resin injected at both ends. Cable 13 passes through the casing 11 and connects to a potentiostat 2 inside the tower. The auxiliary anode assembly 1 is placed approximately 10m from the wind turbine and secured to the seabed with tension steel cables. While the auxiliary anodes will be buried by sediment after a period of operation, the presence of seawater inside ensures their lifespan remains unaffected, allowing them to operate continuously for over 20 years. During high tide, the entire auxiliary anode is submerged by seawater, and the surface potential of the wind turbine pile is between -0.940 and -0.950V (relative to the silver / silver chloride reference electrode). During low tide, the constant current power supply switches to constant current mode, and the auxiliary anode is connected to the wind turbine pile foundation through the bottom mud surface, with the surface potential stabilizing between -0.920 and -0.930V (relative to the silver / silver chloride reference electrode), both of which meet the cathodic protection potential requirements of the wind turbine pile.

[0058] Example 2

[0059] A near-shore subsea pipeline, with a diameter of 305 mm and a length of 1 km, is constantly submerged in seawater and is gradually buried by silt over time. Due to its proximity to the coastline, existing impressed current cathodic protection technology might expose the auxiliary anode above the water surface, and placing the auxiliary anode beneath the pipeline would result in high construction costs. Therefore, this subsea pipeline is protected using the aforementioned impressed current cathodic protection system, the specific installation structure of which is as follows. Figure 9 As shown (i.e.) Figure 9 The protected body 4 is a subsea pipeline. The potentiostat 2 is installed on the coast, with a system output current of 120A, sufficient to protect the entire pipeline. The composite electrode sensor 3 is installed on the pipeline; it only has a reference electrode and requires no other sensors (since it is always below the sea surface, there is no need for seawater velocity measurement devices or pressure sensors). The auxiliary anode in the auxiliary anode assembly 1 and the composite electrode sensor 3 are both connected to the potentiostat 2 via armored seawater-resistant cables.

[0060] The auxiliary anode can be installed in the tidal zone close to the coastline, eliminating the need for underwater construction and making installation more convenient. During high tide, the auxiliary anode is submerged, and the pipe surface potential is -0.940 to -0.950 V (relative to the silver / silver chloride reference electrode). During low tide, the auxiliary anode connects to the subsea pipeline through the bottom mud surface, and the pipe surface potential is -0.890 to -0.900 V (relative to the silver / silver chloride reference electrode). Regardless of the environment, the entire pipeline can reach the protective potential.

[0061] Example 3

[0062] One of the pile foundations of a cross-sea bridge has 12 steel pile legs welded to a steel pier, with a length of about 70m, of which about 40m is above and below the mud surface. After a period of operation, the life of the impressed current system expired, and the aforementioned impressed current cathodic protection system was used for cathodic protection repair to extend its service life.

[0063] The main construction process is as follows: A potentiostat is installed on the pile foundation platform, with a maximum output current of 150A. The auxiliary anode assembly is installed near the platform by divers, and the composite electrode sensor is installed on the pile foundation at the bottom of the platform. Cables are then routed along the pile legs and connected to the potentiostat. The composite electrode sensor is equipped only with a reference electrode and is installed on the upper part of the pile leg at the center of the pile foundation. The auxiliary anode assembly is always in a seawater environment, approximately 10m from the pile foundation, with a pile surface potential of -0.940 to -0.950V (relative to the silver / silver chloride reference electrode), meeting the cathodic protection requirements.

[0064] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An auxiliary anode assembly for an impressed current cathodic protection system, characterized in that, The auxiliary anode assembly (1) includes a housing (11), an auxiliary anode body (12) disposed within the housing (11), and a cable (13). One end of the cable (13) is located inside the housing (11) and electrically connected to the auxiliary anode body (12), while the other end of the cable (13) extends outside the housing (11) and is used for electrical connection to a potentiostat (2). The housing (11) is a sealed structure, and a water inlet (1110) is provided at the top of the housing (11). The shell (11) is used to allow seawater to enter and store the seawater. The bottom of the shell (11) is provided with a plurality of micropores (1130). The seawater in the shell (11) can contact the mud and sand below the shell (11) through the micropores (1130), so that the auxiliary anode body (12) can be electrically connected to the mud and sand below the shell (11) through the seawater in the shell (11). The micropores (1130) can prevent mud and sand from entering the shell (11). The housing (11) includes a top plate (111), a protective cover (112), and a bottom plate (113). The protective cover (112) is a cylindrical structure with openings at both the top and bottom. The top plate (111) is connected to the top opening of the protective cover (112), and the bottom plate (113) is connected to the bottom opening of the protective cover (112). The top plate (111), the protective cover (112), and the bottom plate (113) enclose a cavity (110), and the auxiliary anode body (12) is disposed within the cavity (110). The water inlet (1110) is disposed on the top plate (111), and the micropores (1130) are disposed on the bottom plate (113). The auxiliary anode body (12) is spaced apart from the bottom plate (113), and the auxiliary anode body (12) is suspended within the housing (11).

2. The auxiliary anode assembly as described in claim 1, characterized in that, The pore size of the micropore (1130) is 0.01 mm to 0.25 mm.

3. The auxiliary anode assembly as described in claim 1, characterized in that, The sidewall of the protective cover (112) is an inclined structure that slopes outward from top to bottom, so that the protective cover (112) is a cone-shaped structure as a whole; the size of the bottom plate (113) is larger than the size of the top plate (111).

4. The auxiliary anode assembly as described in claim 1, characterized in that, The base plate (113) includes multiple filter plates (1131) stacked vertically, and each of the filter plates (1131) is provided with micropores (1130); in each pair of adjacent base plates (113), the diameter of the micropores (1130) on the lower base plate (113) is smaller than the diameter of the micropores (1130) on the upper base plate (113).

5. The auxiliary anode assembly as described in claim 1, characterized in that, The density of the bottom plate (113) is less than that of seawater to prevent the shell (11) from sinking into the mud and sand.

6. The auxiliary anode assembly as described in claim 1, characterized in that, The protective cover (112) is made of metal material and has a sacrificial anode.

7. An impressed current cathodic protection system, characterized in that, The device includes an auxiliary anode assembly (1), a composite electrode sensor (3), and a potentiostat (2) as described in any one of claims 1-6. The auxiliary anode assembly (1) is disposed near the protected body (4), and the composite electrode sensor (3) is disposed on the protected body (4). The composite electrode sensor (3) includes a reference electrode (32) for measuring the potential of the protected body (4). The reference electrode (32) is electrically connected to the potentiostat (2), and the auxiliary anode body (12) is electrically connected to the potentiostat (2) via the cable (13).

8. The impressed current cathodic protection system as described in claim 7, characterized in that, The composite electrode sensor (3) also includes a base (31), a seawater flow velocity measuring device (33), and a pressure sensor (34). The reference electrode (32), the seawater flow velocity measuring device (33), and the pressure sensor (34) are all disposed on the base (31). The pressure sensor (34) is disposed above the seawater flow velocity measuring device (33), and both the seawater flow velocity measuring device (33) and the pressure sensor (34) are electrically connected to the potentiostat (2).

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