A sacrificial anode size monitoring device and a method for assessing the protection life of sacrificial anodes.

Abstract

This invention belongs to the field of steel structure corrosion protection technology, and provides a sacrificial anode size monitoring device and a method for assessing the protection period of sacrificial anodes. The monitoring device includes a support cylinder, sensors, monitoring cables, a protective cylinder, and sealing materials. By pre-embedding the monitoring device in the sacrificial anode and periodically measuring the resistance between the sensors, the size of the sacrificial anode can be monitored. This eliminates the need for underwater exploration and the monitoring and analysis of large amounts of current data, providing a more intuitive reflection of the sacrificial anode size. The protection period assessment considers the effect of the linkage between anode current and size, making the prediction more accurate.

Description

Technical Field

[0001] This invention belongs to the field of steel structure corrosion protection technology, specifically relating to a sacrificial anode size monitoring device and a method for assessing the protection life of sacrificial anodes. Background Technology

[0002] Cathodic protection is an effective way to prevent corrosion of steel structures in underwater and submerged areas. Sacrificial anodes provide protection to the steel structure through their own dissolution; however, their protective life ends as the anodes dissolve completely. Regularly monitoring the dissolution of the anodes is crucial for estimating the remaining protective life of the anodes and predicting when to replace the sacrificial anodes.

[0003] The observation of sacrificial anode dissolution and the estimation of remaining protection years mainly rely on underwater exploration by divers to determine the size of the sacrificial anode. Underwater exploration is high-risk, inefficient, and significantly affected by wind and waves, making full coverage difficult. Installing sensors on the sacrificial anode and implementing regular monitoring can obtain information on anode dissolution without the need for underwater exploration. Currently, this method primarily calculates the amount of anode dissolution by monitoring the current generated at the anode, requiring continuous real-time monitoring of the current, resulting in a large amount of data and potential for calculation errors. Therefore, a more intuitive monitoring method reflecting anode size is needed.

[0004] The calculation of the remaining protection life of sacrificial anodes is currently mainly done by obtaining the remaining mass of the anode and comparing it with the initial mass. This calculation method is based on the assumption that the anode mass loss is linearly related to time—that is, the anode current remains constant. However, as the sacrificial anode dissolves, its current gradually decreases, so the loss of the sacrificial anode mass does not satisfy a linear relationship with time. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of this invention is to provide a sacrificial anode size monitoring device to solve the problems of high safety risks and low efficiency in current underwater exploration.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A sacrificial anode size monitoring device, comprising:

[0008] Support cylinder, sensor, monitoring cable, protective cylinder, and sealing material;

[0009] The support cylinder includes a cavity for placing the sensor. The side wall of the cavity is provided with mounting holes for mounting the sensor. There are two or more mounting holes, and the distance between each mounting hole and the cavity opening is different.

[0010] One end of the sensor matches and extends out of the mounting hole, and the other end extends out of the cavity opening. The number of the sensors is the same as the number of the mounting holes, and the sensors do not contact each other.

[0011] One end of the monitoring cable is connected to the end of the sensor that extends out of the cavity;

[0012] The protective cylinder is located at the opening of the support cylinder, and the connection between the monitoring cable and the sensor is located inside the protective cylinder, with the other end of the monitoring cable passing through the protective cylinder;

[0013] The sealing material is disposed inside the support cylinder, inside the protective cylinder, and at the connection between the two.

[0014] Preferably, the support cylinder is made of ceramic material.

[0015] Preferably, the sealing material is epoxy resin, and the sensor is made of copper or a conductive metal.

[0016] Preferably, the sensor is L-shaped, including a short side and a long side. The short side of the sensor matches the mounting hole and extends out of the support cylinder through the mounting hole, while the long side of the sensor is connected to one end of the monitoring cable.

[0017] This invention also discloses a method for assessing the service life of sacrificial anode protection, based on the structure of the aforementioned sacrificial anode size monitoring device, comprising the following steps:

[0018] S1. Install the sacrificial anode size monitoring device inside the sacrificial anode and measure the resistance between adjacent sensors;

[0019] S2. The sacrificial anode is installed on the protected steel structure by underwater welding, and the monitoring cable is led to the water-based data acquisition instrument.

[0020] S3. Periodically measure the resistance between adjacent sensors;

[0021] S4. Using the installation time of the sacrificial anode as the time origin, monitor the resistance between adjacent sensors and record the time when the resistance changes abruptly, denoted as t1. Then, based on the distance from the sensor with the larger distance to the sacrificial anode core among the two adjacent sensors where the resistance changes abruptly, denoted as r1, use the formula... For formula (1), calculate K, where r is the radius of the anode body (substitute r1), L is the length of the anode body, t is the time (substitute t1), and C is a constant determined by the following formula. Formula (2) is used, where r0 is the initial radius of the anode body. This is then applied again... The calculated K and the radius r when the anode body is completely worn out. fSubstitute the values ​​and calculate the time t for the anode to be completely consumed. f Finally, using t e =t f -t1, which is the remaining protection period obtained by formula (3), is denoted as t. e .

[0022] Preferably, in S4, the formula and The derivation process is as follows:

[0023] The anode provides current through its own dissolution, which satisfies Faraday's law, namely:

[0024] It is denoted as (4).

[0025] In the formula, Q is the total amount of charge that can be released by the dissolution of the anode, z is the charge transfer number of the anode dissolution reaction, F is the Faraday constant, η is the current efficiency, M is the molar mass of the anode material, and m is the mass of the anode. Taking the time derivative of both sides of formula (4), we get:

[0026] It is denoted as (5).

[0027] In the formula, I represents the current generated by the anode body due to mass loss.

[0028] On the other hand, assuming the anode body is a cylinder, we have:

[0029] m=(πr 2 LV)ρ A , denoted as (6),

[0030] In the formula, r is the radius of the anode body, L is the length of the anode body, V is the volume of the portion of the iron core enclosed by the anode body, and ρ is the volume of the anode body. A Let the density of the anode be denoted as . Further assume that the length of the anode remains constant and only the radius changes during the dissolution process. Then, taking the time derivative of both sides of (6), we get:

[0031] Recorded as (7),

[0032] During the sacrificial anode protection period, the current flowing through the anode body satisfies Ohm's law, that is:

[0033] It is denoted as (8).

[0034] In the formula, U is the driving voltage, and R is the sacrificial anode water resistance, satisfying:

[0035] Recorded as (9),

[0036] In the formula, ρ S Seawater resistivity

[0037] Combining (5), (7), (8), and (9), and assuming the driving voltage remains constant, we obtain:

[0038] It is denoted as (10).

[0039] In the formula, K is:

[0040] Recorded as (11),

[0041] Separating the variables from formula (10), we get:

[0042] Recorded as (12),

[0043] Integrating both sides, we get:

[0044] Recorded as (13),

[0045] Calculate the three integrals of equation (13) separately, and obtain

[0046] Let it be denoted as (14), where C is a constant, and when t = 0, r = r0, where r0 is the initial radius of the anode body. Therefore:

[0047] Recorded as (15),

[0048] Then we have:

[0049] It is denoted as (16).

[0050] Preferably, in S1, the specific steps for installing the sacrificial anode size monitoring device inside the sacrificial anode are as follows:

[0051] S11. As needed, a placement hole for installing the support cylinder is provided in the center of the iron core of the sacrificial anode;

[0052] S12. Fabricate the support cylinder and install the sensor;

[0053] S13. Install the support cylinder in the placement hole of the iron core of the sacrificial anode and record the distance from each sensor to the iron core;

[0054] S14. Install the iron core onto the sacrificial anode mold and pour the anode body;

[0055] S15. After the anode material cools and solidifies, weld the monitoring cable to the end of the sensor located at the opening of the support cylinder.

[0056] S16. Put on the protective sleeve;

[0057] S17. Fill the support cylinder with waterproof and insulating sealing material until it is level with the top of the protective cylinder.

[0058] Preferably, in step S12, multiple sensors are installed inside the support cylinder, with one end passing through the mounting hole and protruding 1mm to 2mm from the outer wall of the support cylinder, and the other end of the sensor being 5mm to 10mm above the opening of the support cylinder. When installing the sensors, it should be ensured that the sensors do not contact each other.

[0059] Preferably, in step S16, the connection point between the monitoring cable and the sensor is lower than the upper opening of the protective cylinder.

[0060] Preferably, in step S13, if the support tube does not penetrate the anode body, the end of the support tube inside the anode body is closed and the end outside the anode body is open; if the support tube penetrates the anode body, both ends of the support tube are open.

[0061] Compared with the prior art, the beneficial effects of the present invention include:

[0062] In this scheme, sensors are pre-embedded in the sacrificial anode to periodically measure the resistance between the sensors, thereby enabling the monitoring of the sacrificial anode size. This eliminates the need for underwater exploration, monitoring, and analysis of large amounts of current data, providing a more intuitive reflection of the sacrificial anode size. The protection life assessment takes into account the effect of the linkage between anode current and size, making the prediction more accurate. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a schematic diagram of the monitoring device of the present invention installed on the sacrificial anode.

[0065] Figure 2 This is a schematic diagram of the monitoring device of the present invention.

[0066] in:

[0067] 1-Sacrificial anode; 2-Monitoring device; 11-Anode body; 12-Iron core; 21-Support cylinder; 22-Sensor; 23-Monitoring cable; 24-Protective cylinder; 25-Sealing material. Detailed Implementation

[0068] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0070] Example:

[0071] like Figure 1-2 As shown, this embodiment provides a sacrificial anode size monitoring device, including:

[0072] Support cylinder 21, sensor 22, monitoring cable 23, protective cylinder 24, and sealing material 25;

[0073] The support cylinder 21 includes a cavity for placing the sensor 22. The side wall of the cavity is provided with mounting holes for mounting the sensor 22. There are two or more mounting holes. The mounting holes are evenly distributed along the axial and circumferential directions of the support cylinder 21. The cavity can be a structure that is sealed on one side and open on the other side, or a structure that is open on both sides.

[0074] One end of the sensor 22 matches the mounting hole and extends out, while the other end extends out of the cavity opening. The number of sensors 22 is the same as the number of mounting holes. Adjacent sensors 22 do not contact each other. In this embodiment, the sensor 22 is made of copper or conductive metal, is L-shaped, and has a circular cross-section, including a short side and a long side. The short side of the sensor 22 matches the mounting hole and extends out of the support cylinder 21 through the mounting hole, while the long side of the sensor 22 extends out of the cavity opening.

[0075] One end of the monitoring cable 23 is connected to the end of the sensor 22 that extends out of the cavity;

[0076] The protective sleeve 24 is fitted into the cavity of the support sleeve 21, and the connection between the monitoring cable 23 and the sensor 22 is located inside the protective sleeve 24, with the other end of the monitoring cable 23 passing through the protective sleeve 24.

[0077] Sealing material 25 is provided inside the support cylinder 21, inside the protective cylinder 24, and at the connection between the two.

[0078] Specifically, the support cylinder 21 is made of ceramic.

[0079] Specifically, the sealing material 25 is epoxy resin.

[0080] This invention also discloses a method for assessing the service life of sacrificial anode protection, based on the structure of the aforementioned sacrificial anode size monitoring device, comprising the following steps:

[0081] S1. Install the sacrificial anode size monitoring device 2 inside the sacrificial anode 1 and measure the resistance between adjacent sensors 22. In this embodiment, the sacrificial anode 1 includes an anode body 11 and an iron core 12.

[0082] S2. The sacrificial anode 1 is installed on the protected steel structure by underwater welding, and the monitoring cable 23 is led to the water-based data acquisition instrument.

[0083] S3. Periodically measure the resistance between adjacent sensors 22;

[0084] S4. Taking the installation time of the sacrificial anode as the time origin, monitor the resistance between adjacent sensors 22, record the time when the resistance changes abruptly, denoted as t1, and based on the distance from the sensor with the larger distance from the sacrificial anode core among the two adjacent sensors 22 where the resistance change occurs, denoted as r1, use the formula... For formula (1), calculate K, where r is the radius of anode body 11, substituting r1, L is the length of anode body 11, t is time, substituting t1, and C is a constant, determined by the following formula: Formula (2) is used, where r0 is the initial radius of the anode body 11. This is then used again... The calculated K and the radius r when the anode body 11 is completely worn out are given above. f Substitute the values ​​and calculate the time t for the anode to be completely consumed. f Finally, using t e =t f -t1, which is the remaining protection period obtained from formula (3), is denoted as t. e .

[0085] Specifically, in S4, the formula and The derivation process is as follows:

[0086] The anode 11 provides current through its own dissolution, satisfying Faraday's law, namely:

[0087] It is denoted as (4).

[0088] In the formula, Q is the total amount of charge that can be released when the anode 11 dissolves, z is the charge transfer number of the anode 11 dissolution reaction, F is the Faraday constant, η is the current efficiency, M is the molar mass of the anode 11 material, and m is the mass of the anode 11. Taking the time derivative of both sides of formula (4), we get:

[0089] It is denoted as (5).

[0090] In the formula, I is the current generated by the anode body 11 due to mass loss.

[0091] On the other hand, assuming the anode body is a cylinder, we have:

[0092] m=(πr 2 LV)ρ A , denoted as (6),

[0093] In the formula, r is the radius of the anode body 11, L is the length of the anode body 11, V is the volume of the portion of the iron core 12 enclosed by the anode body 11, and ρ A Let the density of the anode body 11 be denoted as . Further assume that the length of the anode body 11 remains constant during the dissolution process, while only the radius changes. Then, taking the time derivative of both sides of (6), we obtain:

[0094] Recorded as (7),

[0095] During the sacrificial anode protection period, the current flowing through anode body 11 satisfies Ohm's law, that is:

[0096] It is denoted as (8).

[0097] In the formula, U is the driving voltage, and R is the sacrificial anode water resistance, satisfying:

[0098] Recorded as (9),

[0099] In the formula, ρ S Seawater resistivity

[0100] Combining (5), (7), (8), and (9), and assuming the driving voltage remains constant, we obtain:

[0101] It is denoted as (10).

[0102] In the formula, K is:

[0103] Recorded as (11),

[0104] Separating the variables from formula (10), we get:

[0105] Recorded as (12),

[0106] Integrating both sides, we get:

[0107] Recorded as (13),

[0108] Calculate the three integrals of equation (13) separately, and obtain

[0109] Recorded as (14),

[0110] Where C is a constant, and when t = 0, r = r0, where r0 is the initial radius of the anode body 11. Therefore:

[0111] Recorded as (15),

[0112] Then we have:

[0113] It is denoted as (16).

[0114] Specifically, in S1, the steps for installing the sacrificial anode size monitoring device 2 inside the sacrificial anode 1 are as follows:

[0115] S11. As needed, a placement hole for mounting the support cylinder 21 is provided at the center of the iron core 12 of the sacrificial anode 1;

[0116] S12. Fabricate support cylinder 21 and install sensor 22;

[0117] S13. Install the support cylinder 21 in the placement hole of the iron core 12 of the sacrificial anode 1, and record the distance from each sensor 22 to the iron core 12. One support cylinder 21 can be installed on the sacrificial anode 1, or multiple support cylinders 21 can be installed at different parts such as the end and middle of the sacrificial anode 1.

[0118] S14. Install the iron core 12 onto the sacrificial anode mold and pour the anode body 11;

[0119] S15. After the anode body 11 material cools and solidifies, weld the monitoring cable 23 to the end of the sensor 22 located at the opening of the support cylinder 21.

[0120] S16, Put on the protective sleeve 24;

[0121] S17. Fill the support cylinder 21 with waterproof and insulating sealing material 25 until it is level with the top of the protective cylinder 24.

[0122] Specifically, in step S12, multiple sensors 22 are installed inside the support cylinder 21, with one end passing through the mounting hole and protruding 1mm to 2mm from the outer wall of the support cylinder 21. The other end of the sensor 22 is 5mm to 10mm above the opening of the support cylinder 21. When installing the sensor 22, it should be ensured that the sensors 22 do not contact each other.

[0123] Specifically, in step S16, the connection point between the monitoring cable 23 and the sensor 22 is lower than the upper opening of the protective cylinder 24.

[0124] Specifically, in step S13, since the cavity can be a structure that is sealed at one end and open at the other, or a structure that is open on both sides, it has two structures. Therefore, the following situations apply:

[0125] If the support cylinder 21 does not penetrate the anode body 11, the end of the support cylinder 21 inside the anode body 11 is closed and the end outside the anode body 11 is open. If the support cylinder 21 penetrates the anode body 11, both ends of the support cylinder 21 are open.

[0126] Before installing the sacrificial anode, the resistance between adjacent sensors is measured. The sacrificial anode is installed on a protected steel structure via underwater welding, and a monitoring cable is led to a data acquisition instrument on the surface. The resistance between adjacent sensors is measured monthly. As the anode body dissolves, the sensors are exposed to seawater, with sensors closer to the anode surface being exposed first. By comparing the resistance measured before anode installation or with previous measurements, if a sudden change in resistance is detected between a sensor and an adjacent sensor closer to the core 12, it indicates that the radius of the anode body 11 has decreased to the location of that sensor. The radius is used to assess anode wear and remaining service life. This invention monitors the size of the sacrificial anode by pre-embedding sensors in the sacrificial anode and periodically measuring the resistance between them. Compared to existing methods, it eliminates the need for underwater exploration, monitoring and analyzing large amounts of current data, provides a more intuitive reflection of the sacrificial anode size, and considers the linkage between anode current and size in the protection life assessment, making predictions more accurate.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for assessing the service life of sacrificial anode protection, characterized in that, Applied to a sacrificial anode size monitoring device, the sacrificial anode size monitoring device comprising: Support cylinder, sensor, monitoring cable, protective cylinder, and sealing material; The support cylinder includes a cavity for placing the sensor. The side wall of the cavity is provided with mounting holes for mounting the sensor. There are two or more mounting holes, and the distance between each mounting hole and the cavity opening is different. One end of the sensor matches and extends out of the mounting hole, and the other end extends out of the cavity opening. The number of the sensors is the same as the number of the mounting holes, and the sensors do not contact each other. One end of the monitoring cable is connected to the end of the sensor that extends out of the cavity; The protective cylinder is located at the opening of the support cylinder, and the connection between the monitoring cable and the sensor is located inside the protective cylinder, with the other end of the monitoring cable passing through the protective cylinder; The sealing material is disposed inside the support cylinder, inside the protective cylinder, and at the connection between the two. The method for assessing the service life of sacrificial anode protection includes the following steps: S1. Install the sacrificial anode size monitoring device inside the sacrificial anode and measure the resistance between adjacent sensors; S2. The sacrificial anode is installed on the protected steel structure by underwater welding, and the monitoring cable is led to the water-based data acquisition instrument. S3. Periodically measure the resistance between adjacent sensors; S4. Using the installation time of the sacrificial anode as the time origin, monitor the resistance between adjacent sensors and record the time when the resistance changes abruptly, denoted as t1. Then, based on the distance from the sensor with the larger distance to the sacrificial anode core among the two adjacent sensors where the resistance changes abruptly, denoted as r1, use the formula... For formula (1), calculate K, where r is the radius of the anode body (replace r1), L is the length of the sacrificial anode, t is the time (replace t1), and C is a constant determined by the following formula. Formula (2) is used, where r0 is the initial radius of the anode body. This is then applied again... The calculated K and the radius r when the anode body is completely worn out. f Substitute the values ​​and calculate the time t for the anode to be completely consumed. f Finally, using t e =t f -t1, which is the remaining protection period obtained by formula (3), is denoted as t. e .

2. The method for assessing the service life of sacrificial anode protection according to claim 1, characterized in that, The support cylinder is made of ceramic.

3. The method for assessing the service life of sacrificial anode protection according to claim 1, characterized in that, The sealing material is epoxy resin.

4. The method for assessing the service life of sacrificial anode protection according to claim 1, characterized in that, The sensor is L-shaped, including a short side and a long side. The short side of the sensor matches the mounting hole and extends out of the support cylinder through the mounting hole. The long side of the sensor is connected to one end of the monitoring cable.

5. The method for assessing the service life of sacrificial anode protection according to claim 1, characterized in that, In S4, the formula and The derivation process is as follows: The anode provides current through its own dissolution, which satisfies Faraday's law, namely: In the formula, Q is the total amount of charge that can be released by the dissolution of the anode, z is the charge transfer number of the anode dissolution reaction, F is the Faraday constant, η is the current efficiency, M is the molar mass of the anode material, and m is the mass of the anode. Taking the time derivative of both sides of formula (4), we get: In the formula, I represents the current generated by the anode body due to mass loss. On the other hand, assuming the anode body is a cylinder, we have: m=(πr 2 LV)ρ A , denoted as (6), In the formula, r is the radius of the anode body, L is the length of the anode body, V is the volume of the portion of the iron core enclosed by the anode body, and ρ is the volume of the anode body. A Let the density of the anode be denoted as . Further assume that the length of the anode remains constant and only the radius changes during the dissolution process. Then, taking the time derivative of both sides of (6), we get: During the sacrificial anode protection period, the current flowing through the anode body satisfies Ohm's law, that is: In the formula, U is the driving voltage, and R is the sacrificial anode water resistance, satisfying: In the formula, ρ S Seawater resistivity Combining (5), (7), (8), and (9), and assuming the driving voltage remains constant, we obtain: In the formula, K is: Separating the variables from formula (10), we get: Integrating both sides, we get: Calculate the three integrals of equation (13) separately, and obtain Where C is a constant, and when t = 0, r = r0, where r0 is the initial radius of the anode body, therefore: Then we have:

6. The method for assessing the service life of sacrificial anode protection according to claim 1, characterized in that, In S1, the specific steps for installing the sacrificial anode size monitoring device inside the sacrificial anode are as follows: S11. As needed, a placement hole for installing the support cylinder is provided in the center of the iron core of the sacrificial anode; S12. Fabricate the support cylinder and install the sensor; S13. Install the support cylinder in the placement hole of the iron core of the sacrificial anode and record the distance from each sensor to the iron core; S14. Install the iron core onto the sacrificial anode mold and pour the anode body; S15. After the anode material cools and solidifies, weld the monitoring cable to the end of the sensor located at the opening of the support cylinder. S16. Put on the protective sleeve; S17. Fill the support cylinder with waterproof and insulating sealing material until it is level with the top of the protective cylinder.

7. The method for assessing the service life of sacrificial anode protection according to claim 6, characterized in that, In step S12, multiple sensors are installed inside the support cylinder, with one end passing through the mounting hole and protruding 1mm to 2mm from the outer wall of the support cylinder. The other end of the sensor is 5mm to 10mm above the opening of the support cylinder. When installing the sensors, it should be ensured that the sensors do not contact each other.

8. The method for assessing the service life of sacrificial anode protection according to claim 6, characterized in that, In step S16, the connection point between the monitoring cable and the sensor is lower than the upper opening of the protective cylinder.

9. The method for assessing the service life of sacrificial anode protection according to claim 6, characterized in that, In step S13, if the support tube does not penetrate the sacrificial anode, the end of the support tube inside the sacrificial anode is closed and the end outside the sacrificial anode is open. If the support tube penetrates the sacrificial anode, both ends of the support tube are open.

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