Simulation calculation method and system for critical conductivity of chain structure external current protection

Abstract

The application discloses a kind of critical conductivity simulation calculation method and system of chain structure impressed current protection, by building COMSOL simulation model, according to wire diameter, chain structure size, metal material conductivity, set current physical field related parameters in COMSOL software, for simulating calculation under different conductivity caused potential attenuation;According to the seawater conductivity obtained in test, the conductivity of metal material, polarization curve, set the secondary current distribution physical field related parameters in COMSOL software, and combine the potential attenuation obtained in current physical field as boundary condition simulation potential distribution under steady state in seawater, if potential distribution reaches the requirement of protection potential, the conductivity corresponding to potential attenuation at this time is critical conductivity.The method can accurately and conveniently evaluate the critical conductivity of chain structure impressed current cathodic protection, and provide a reference for the design of chain structure impressed current cathodic protection system.

Description

Technical Field

[0001] This invention relates to the field of cathodic protection potential simulation calculation for metal corrosion, and particularly to a method and system for simulating the critical conductivity of chain-structure applied current protection. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Floating offshore platforms in deep seas typically use mooring chains for anchoring, and these chains must withstand long-term corrosion in seawater without breaking. Impressed current cathodic protection (ICP) offers advantages that other corrosion protection methods struggle to match, such as long protection periods, adjustability, low pollution, and high efficiency. However, the chain structure of mooring chains is non-rigid, making it difficult to meet the electrical conductivity requirements of ICP. Impressed current cathodic protection can be improved by increasing the conductivity of the chain structure. To provide important reference for the design of ICP systems for chain structures, current technologies typically employ experimental methods to determine whether ICP can be applied to chain structures and thus determine their critical conductivity. However, experimental methods are time-consuming and suffer from high error rates and costs. Therefore, providing a simulation method that can accurately and conveniently evaluate the critical conductivity of chain structures for ICP, and thus provide a reference for the design of ICP systems for chain structures, is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method and system for simulating and calculating the critical conductivity of impressed current protection for chain structures. This method can reduce experimental costs and time, and accurately and conveniently calculate the critical conductivity of impressed current cathodic protection for chain structures, providing a reference for the design of impressed current cathodic protection systems for chain structures.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect of the present invention, a method for simulating and calculating the critical conductivity of an applied current protection system with a chain-like structure is provided, comprising the following steps:

[0007] Step 1: Obtain the basic parameters required for the simulation of the physical field of current, establish a chain structure simulation model based on the basic parameters, and set the conductivity, relative permittivity and magnitude of the applied protective current of the chain structure metal material;

[0008] Step 2: Calculate the potential decay caused by the resistor to determine the critical conductivity;

[0009] Step 3: Obtain the basic parameters required for simulating the physical field of secondary current distribution, establish a chain structure simulation model based on the basic parameters, set the electrolyte conductivity and electrode reaction kinetic parameters of seawater and materials, and set the boundary conditions of the chain structure based on the potential decay obtained in Step 2.

[0010] Step 4: Calculate the cathodic protection potential of the chain-like structure in seawater to obtain the cathodic protection potential of the impressed current;

[0011] Step 5: Determine whether the impressed current cathodic protection potential is within the specified range of the standard protection potential. If yes, the critical conductivity in Step 2 is the critical conductivity of the chain structure applying impressed current cathodic protection. If no, increase the conductivity and return to Step 2 to recalculate the potential decay until the impressed current cathodic protection potential is within the specified range. Then, the increased conductivity is considered to be the critical conductivity.

[0012] In some embodiments of the present invention, the basic parameters in step 1 include the wire diameter, the size of the chain structure, the conductivity of the metallic material, and the relative permittivity.

[0013] In some embodiments of the present invention, the process of calculating the potential decay in step 2 is as follows: the auxiliary anode is set as the terminal, I1 current is passed in, one end of the chain structure is set as ground, the chain structure is divided into free tetrahedral meshes, and then the different conductivity of the wires is calculated. The maximum value of the calculated potential result minus the minimum value is the potential decay.

[0014] In some embodiments of the present invention, the basic parameters in step 3 include the conductivity of the seawater electrolyte and the polarization curve of the metallic material.

[0015] In some embodiments of the present invention, the polarization curve, a basic parameter required for simulating the physical field of secondary current distribution, is measured by a three-electrode system of an electrochemical workstation. The counter electrode uses the same material as the auxiliary anode in the actual impressed current protection system, the working electrode uses the same material with a chain structure, and the reference electrode uses Ag / AgCl saturated with KCl.

[0016] In some embodiments of the present invention, the polarization curve measurement scan rate is no greater than 0.005V / s, and the voltage scan range is determined according to the open circuit potential.

[0017] In some embodiments of the present invention, the calculation process of the applied current cathodic protection potential in step 4 is as follows: the chain structure is divided into free tetrahedral meshes, and then the potential difference between the metal surface potential of the chain structure and the electrolyte on the contact surface is calculated, which is the applied current cathodic protection potential.

[0018] In a second aspect of the invention, a simulation calculation system for the critical conductivity of impressed current cathodic protection is provided, comprising:

[0019] The model building module is configured to: acquire the basic parameters required for the simulation of the current physical field, build a chain structure simulation model based on the basic parameters, and set the conductivity, relative permittivity and magnitude of the applied protective current of the chain structure metal material.

[0020] The potential decay calculation module is configured to: calculate the potential decay generated by the resistor and determine the critical conductivity;

[0021] The boundary condition acquisition module is configured to: acquire the basic parameters required for the physical field simulation of the secondary current distribution, establish a chain structure simulation model based on the basic parameters, set the electrolyte conductivity and electrode reaction kinetic parameters of seawater and materials, and set the boundary conditions of the chain structure based on the potential decay obtained in step 2.

[0022] The potential calculation module is configured to calculate the cathodic protection potential of the chain structure in seawater under impressed current, and obtain the cathodic protection potential of impressed current.

[0023] The critical conductivity determination module is configured to: determine whether the applied current cathodic protection potential is within the specified range of the standard protection potential; if so, the critical conductivity in step 2 is the critical conductivity of the chain structure applying applied current cathodic protection; if not, increase the conductivity and return to step 2 to recalculate the potential decay until the applied current cathodic protection potential is within the specified range, then the increased conductivity is considered to be the critical conductivity.

[0024] One or more technical solutions of the present invention have the following beneficial effects:

[0025] (1) The critical conductivity simulation calculation method for impressed current protection of chain structure provided by the present invention uses COMSOL to simulate the potential distribution of impressed current cathodic protection of chain structure under different conductivity, thereby calculating the critical conductivity. Compared with the experimental method, it can reduce experimental cost and time, and accurately and conveniently calculate the critical conductivity of impressed current cathodic protection of chain structure, providing a reference for the design of impressed current cathodic protection system of chain structure.

[0026] (2) Since the conductivity of the material cannot be arbitrarily changed according to the required specifications during the experiment, the simulation calculation method provided by this invention can easily set the conductivity by simply changing the material properties, which is cost-free and fast. The simulation can quickly build a digital physical model based on the actual size of the chain structure, while the experiment requires obtaining a physical sample, which is costly and slow.

[0027] (3) The present invention uses conductivity parameters and electrode reaction kinetic parameters as the basis for potential decay simulation calculation, and ensures the reliability of simulation calculation numerical results based on polarization curve parameters obtained from actual electrochemical tests. Attached Figure Description

[0028] Figure 1 This is a flowchart of the simulation calculation method for the critical conductivity of the chain-like structure applied current protection according to the present invention.

[0029] Figure 2 This is the physical model of the chain-like structure impressed current cathodic protection established based on COMSOL in the method of this invention;

[0030] Figure 3 This refers to the potential decay of the chain structure under different conductivity levels in Embodiment 1 of the present invention.

[0031] Figure 4 The cathodic protection potential distribution of the applied current in the physical field (cd) of the secondary current distribution of the 8mm diameter chain structure in Embodiment 1 of the present invention is shown.

[0032] Figure 5 This refers to the distribution of the applied current cathodic protection potential of a local chain link in the physical field (cd) of the secondary current distribution of the 8mm diameter chain structure in Embodiment 1 of the present invention under critical conductivity. Detailed Implementation

[0033] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, 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.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] In cathodic protection engineering, potential is a crucial indicator for evaluating the effectiveness of cathodic protection; therefore, understanding the potential distribution on the surface of the protected object is essential. This invention uses COMSOL to simulate the potential distribution of a chain structure under impressed current cathodic protection at different conductivity levels, thereby calculating the critical conductivity. This reduces experimental costs and time, and provides an accurate and convenient way to calculate the critical conductivity of a chain structure under impressed current cathodic protection, offering a reference for the design of chain structure impressed current cathodic protection systems.

[0036] Example 1

[0037] A method for simulating and calculating the critical conductivity of an applied current protection system with a chain-like structure, such as... Figure 1 As shown, it includes the following steps:

[0038] Step 1: Obtain the basic parameters required for the current physics (ec) simulation, including the conductor diameter, chain structure dimensions, and the conductivity and relative permittivity of the metallic material. The conductor diameter is determined based on the diameter of the specific conductor used in the experiment. The chain structure dimensions include the nominal diameter of the cross-section at the connection point of adjacent links, the maximum transverse width of the chain link, the maximum longitudinal length of the chain link, and the number of chain links. The conductivity and relative permittivity of the metallic material are determined according to the actual material used. A chain structure simulation model is built in the current physics (ec) simulation of COMSOL software for potential decay calculation. Specifically, a chain structure physical model is established based on the obtained basic parameters. To ensure a solution and reduce computation time, the conductor physical model is constructed as a cylinder, which runs through the chain structure, connecting the gaps between the chain links. Then, the conductivity, relative permittivity, and applied protective current of the chain structure's metallic material are set. The applied protective current is set based on the surface area of ​​the chain structure and the applied protective current density. Furthermore, the applied protective current density is determined based on the material's environment and surface condition.

[0039] Step 2: Calculate the potential decay caused by resistance. The calculation process is as follows: Set the auxiliary anode as the terminal and pass an I1 current through it. Set one end of the chain structure as ground. Divide the chain structure into a free tetrahedral mesh. Then, calculate the different conductivity values ​​of the wires. Measure the resistance values ​​at both ends of the cylindrical sample using a resistance measuring device. After calculating the resistivity, take its reciprocal as the conductivity. Subtract the minimum value from the maximum calculated potential value to obtain the potential decay. The wires with different conductivity values ​​are generally, but not limited to, gradually increasing from 0.01 S / m until the potential decay value is less than 0.3V. Plot the logarithm of the conductivity as the x-axis and the potential decay value as the y-axis and connect the lines. The conductivity corresponding to 0.3V on the y-axis is the critical conductivity before verification.

[0040] Step 3: Obtain the basic parameters required for simulating the physical field (cd) of the secondary current distribution, including the conductivity of the seawater electrolyte and the polarization curves of the metallic materials. The conductivity of the seawater electrolyte in the environment is obtained by measuring it with a conductivity meter. The polarization curves are measured using a three-electrode system on an electrochemical workstation. The counter electrode uses the same material as the auxiliary anode in the actual impressed current protection system, the working electrode uses the same material as the chain-like structure, and the reference electrode uses Ag / AgCl saturated with KCl. The working electrode uses a cylindrical sample with the same diameter as the chain-like structure, with a wire welded to the end and sealed with epoxy resin, leaving only the end face as the working surface. The polarization curve measurement scan rate is no greater than 0. 0.005V / s, the voltage scan range is determined based on the open circuit potential; a chain structure simulation model is constructed in the secondary current distribution (cd) in COMSOL software to calculate the potential distribution on the surface of the chain structure after contact corrosion with seawater under applied current cathodic protection. The electrolyte conductivity of seawater and material, electrode reaction kinetic parameters are set in the simulation model. The electrode reaction kinetic parameters are set according to the polarization curve fitting parameters of the metal material. The electrode reaction kinetic parameters of the metal material include equilibrium potential, exchange current density and Tafel cathode slope. The boundary conditions of the chain structure are set according to the potential decay obtained in step 2. The boundary conditions are the electrode potentials on each chain link.

[0041] Step 4: Calculate the cathodic protection potential of the chain structure in seawater with applied current. Specifically, the chain structure is divided into free tetrahedral meshes, and then the potential difference between the metal surface potential of the chain structure and the electrolyte on the contact surface is calculated, which is the cathodic protection potential with applied current.

[0042] The specific calculation process for the potential difference is as follows:

[0043] -n·i l =0, -n·i s =0

[0044] n·i l =i total

[0045]

[0046] η = E ct -E eq E ct =φ s，ext -φ l

[0047]

[0048]

[0049]

[0050] φ l =phil,φ s =phis

[0051] Where i1 is the electrolyte current density, i s Let E be the current density of the metallic structure (or solid material), η be the overpotential, and E be the current density of the solid structure (or solid material). eq φ1 is the equilibrium potential, φ2 is the electrolyte potential, φ3 is the surface potential of the metal structure (or solid material), σ1 is the electrolyte conductivity, and σ2 is the electrolyte conductivity. s E represents the electrical conductivity of a metallic structure (or solid material), where n is the unit vector in the normal direction. ct Let i be the electrode potential, i0 be the exchange current density, and A be the current density. c The cathode Tafel slope, φ s，ext Q is the potential of the metal structure (or solid material) at the interface with the electrolyte, Q1 is the charge of the electrolyte, and Q... s For the electric charge of a metallic structure (or solid material), i loc This represents the local current density.

[0052] Step 5: Determine whether the impressed current cathodic protection potential is within the specified range of the standard protection potential. If yes, the critical conductivity in Step 2 is the critical conductivity of the chain structure applying impressed current cathodic protection. If no, increase the conductivity and return to Step 2 to recalculate the potential decay until the impressed current cathodic protection potential is within the specified range, then it is considered to be the critical conductivity.

[0053] This embodiment uses COMSOL version 5.5 software. First, the basic parameters required for the current physics (ec) simulation are obtained. This embodiment uses a wire diameter of 3mm, and chain structure diameters of 8mm, 36mm, and 81mm, each chain structure consisting of 5 links. The conductivity of the metal material in the chain structure is set to 10. 6 The relative permittivity is 1, the conductivity of seawater is set to 0.000001S / m (here, conductivity refers to electronic conductivity; seawater should be 0, but it is set to this value to provide a solution to the equation, which does not affect the calculation results), and the relative permittivity is set to 70.

[0054] Based on the dimensions of the aforementioned chain-like structure, its physical model is constructed using CAD software, such as... Figure 2 As shown, the physical model is then imported using geometry in COMSOL to form a union.

[0055] The auxiliary anode is set as the terminal, and an I1 current is applied based on the surface area of ​​the chain structure. One end of the chain structure is grounded. A free tetrahedral mesh is used to divide the chain structure, with a minimum element size of 10⁻⁶ m, a maximum element size of 0.105 m, a maximum element growth rate of 1.35, a curvature factor of 0.3, and a narrow region resolution of 0.85. After calculation, the conductor conductivity is changed, and the above steps are repeated to obtain the desired result. Figure 2 The potential decay of the chain structure is shown under different conductivity values.

[0056] Figure 3 It can be seen that in the initial stage of increasing conductivity from 0.01 S / m, a small increase in conductivity causes a rapid decrease in potential decay. When the conductivity is greater than about 1 S / m, the decrease in potential decay with increasing conductivity is not significant. However, for the maximum voltage drop of 0.3V generally specified for impressed current cathodic protection (ICCP), the potential decay value is still relatively large. Potential decay is related to the anchor chain diameter. The potential decay curve of the 81mm diameter chain link is generally higher than that of the 36mm and 8mm diameter anchor chains. When the conductivity is 6369 S / m, the potential decay of the 8mm, 36mm, and 81mm diameter chain links are 0.3084mV, 2.82mV, and 6.87mV, respectively, indicating that with the same number of chain links, the larger the anchor chain diameter, the greater the potential decay. For this model, the conductivity value at which the potential decays to 0.3V is called the critical conductivity. When the conductivity is greater than the critical conductivity, the chain structure can achieve ICCP protection. Therefore, the critical conductivity of the 8mm diameter anchor chain is 10S / m, the critical conductivity of the 36mm diameter anchor chain is 60S / m, and the critical conductivity of the 81mm diameter anchor chain is 140S / m.

[0057] To obtain the basic parameters required for simulating the physical field (cd) of the secondary current distribution, the conductivity of the seawater electrolyte was set to 4 S / m. The polarization curves of the metallic materials were obtained using an electrochemical workstation, specifically a CHI 660E electrochemical workstation in a simulated seawater solution. Before testing, the working electrode was sequentially polished with 400-mesh, 800-mesh, 1000-mesh, and 1200-mesh sandpaper until smooth, then cleaned with ultrapure water and anhydrous ethanol, and dried with absorbent paper. The reference electrode was Ag / AgCl in saturated KCl, and the counter electrode was a mixed metal oxide electrode (MMO). First, the open-circuit potential was measured for 1800 s. After the electrode surface stabilized, the polarization curve was measured. The polarization curve measurement scan rate was 0.005 V / s, and the voltage scan range was determined based on the open-circuit potential, with a starting voltage of -1.2 V and a ending voltage of 0 V.

[0058] By fitting the obtained polarization curve parameters, the cathode Tafel slope was found to be -113mV, the exchange current density was 0.205A / m2, and the equilibrium potential was -0.56V. These parameters were then set at the electrode reaction interface below the electrode surface in COMSOL.

[0059] Based on the potential decay value of the reference chain structure with a critical conductivity of 8 mm, boundary conditions were set, with electrode potentials of each chain link being -1.097V, -1.065V, -1.031V, -0.99V, and -0.9V, respectively. Then, a mesh was generated, and the cathodic protection potential distribution of the chain structure under applied current was calculated as follows: Figure 4 and Figure 5 As shown.

[0060] Figure 4 and Figure 5 It can be seen that the potential is within the range of the protection potential requirement, so the critical conductivity of the 8mm diameter anchor chain is determined to be 10S / m.

[0061] Example 2

[0062] The purpose of this embodiment is to provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method.

[0063] Example 3

[0064] The purpose of this embodiment is to provide a computer-readable storage medium. A computer-readable storage medium stores a computer program thereon, which, when executed by a processor, performs the steps of the above-described method.

[0065] Example 4

[0066] The purpose of this embodiment is to provide a simulation calculation system for the critical conductivity of impressed current cathodic protection, including:

[0067] The model building module is configured to: acquire the basic parameters required for the simulation of the current (ec) physical field, build a chain-like physical model based on the basic parameters, and set the conductivity, relative permittivity and magnitude of the applied protective current of the chain-like metallic material.

[0068] The potential decay calculation module is configured to: calculate the potential decay generated by the resistor and determine the critical conductivity;

[0069] The boundary condition acquisition module is configured to: acquire the basic parameters required for the simulation of the secondary current distribution physical field (cd), set the electrolyte conductivity and electrode reaction kinetic parameters of seawater and materials, and set the boundary conditions of the chain structure based on the potential decay obtained in step 2.

[0070] The potential calculation module is configured to calculate the cathodic protection potential of the chain structure in seawater under impressed current, and obtain the cathodic protection potential of impressed current.

[0071] The critical conductivity determination module is configured to: determine whether the applied current cathodic protection potential is within the range specified by the standard protection potential; if so, the critical conductivity in step 2 is the critical conductivity of the chain structure applying applied current cathodic protection.

[0072] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0073] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0074] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for simulating and calculating the critical conductivity of an applied current protection system with a chain-like structure, characterized in that, Includes the following steps: Step 1: Obtain the basic parameters required for the simulation of the physical field of current, establish a chain structure simulation model based on the basic parameters, and set the conductivity, relative permittivity and magnitude of the applied protective current of the chain structure metal material; Step 2: Calculate the potential decay caused by the resistor to determine the critical conductivity; Step 3: Obtain the basic parameters required for simulating the physical field of secondary current distribution, establish a chain structure simulation model based on the basic parameters, set the electrolyte conductivity and electrode reaction kinetic parameters of seawater and materials, and set the boundary conditions of the chain structure based on the potential decay obtained in Step 2. Step 4: Calculate the cathodic protection potential of the chain-like structure in seawater to obtain the cathodic protection potential of the impressed current; Step 5: Determine whether the impressed current cathodic protection potential is within the specified range of the standard protection potential. If yes, the critical conductivity in Step 2 is the critical conductivity of the chain structure applying impressed current cathodic protection. If no, increase the conductivity and return to Step 2 to recalculate the potential decay until the impressed current cathodic protection potential is within the specified range. Then, the increased conductivity is considered to be the critical conductivity. The process of calculating potential decay in step 2 is as follows: set the auxiliary anode as the terminal, pass in I1 current, set one end of the chain structure as ground, divide the chain structure into free tetrahedral meshes, and then calculate the different conductivity of the wires. The maximum value of the calculated potential result minus the minimum value is the potential decay. The calculation process of the impressed current cathodic protection potential in step 4 is as follows: the chain structure is divided into free tetrahedral meshes, and then the potential difference between the metal surface potential of the chain structure and the electrolyte on the contact surface is calculated, which is the impressed current cathodic protection potential.

2. The method for simulating and calculating the critical conductivity of the chain-structure applied current protection as described in claim 1, characterized in that, The basic parameters in step 1 are the wire diameter, the size of the chain structure, the conductivity of the metallic material, and the relative permittivity.

3. The method for simulating and calculating the critical conductivity of the chain-like structure under applied current protection as described in claim 1, characterized in that, The basic parameters in step 3 are the conductivity of the seawater electrolyte and the polarization curve of the metallic material.

4. The method for simulating and calculating the critical conductivity of the chain-like structure applied current protection as described in claim 3, characterized in that, The polarization curves, the basic parameters required for simulating the physical field of secondary current distribution, were measured using a three-electrode system on an electrochemical workstation. The counter electrode used the same material as the auxiliary anode in the actual impressed current protection system, the working electrode used the same material with a chain-like structure, and the reference electrode used Ag / AgCl saturated with KCl.

5. The method for simulating and calculating the critical conductivity of the chain-like structure under applied current protection as described in claim 4, characterized in that, The polarization curve measurement scan rate should not exceed 0.005V / s, and the voltage scan range should be determined based on the open circuit potential.

6. A critical conductivity simulation calculation system for chain-structure impressed current protection using the method described in claim 1, characterized in that, include: The model building module is configured to: acquire the basic parameters required for the simulation of the current physical field, build a chain structure simulation model based on the basic parameters, and set the conductivity, relative permittivity and magnitude of the applied protective current of the chain structure metal material. The potential decay calculation module is configured to: calculate the potential decay generated by the resistor and determine the critical conductivity; The boundary condition acquisition module is configured to: acquire the basic parameters required for the physical field simulation of the secondary current distribution, establish a chain structure simulation model based on the basic parameters, set the electrolyte conductivity and electrode reaction kinetic parameters of seawater and materials, and set the boundary conditions of the chain structure based on the potential decay obtained in step 2. The potential calculation module is configured to calculate the cathodic protection potential of the chain structure in seawater under impressed current, and obtain the cathodic protection potential of impressed current. The critical conductivity determination module is configured to: determine whether the applied current cathodic protection potential is within the specified range of the standard protection potential; if so, the critical conductivity in step 2 is the critical conductivity of the chain structure applying applied current cathodic protection; if not, increase the conductivity and return to step 2 to recalculate the potential decay until the applied current cathodic protection potential is within the specified range, then the increased conductivity is considered to be the critical conductivity.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method described in any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it performs the steps of the method described in any one of claims 1-5 above.

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