A corrosion rate detection device for earth-covered storage tanks after cathodic protection

Abstract

The present invention provides a corrosion rate detection device for earth-covered storage tanks after cathodic protection, which belongs to the technical field of detection equipment for measuring electrical variables, and comprises: a tank body, a guard plate, a base, a spherical head, a corrosion rate detection mechanism and a computing chip, wherein bases are symmetrically fixedly connected to the bottom of the tank body on both sides, spherical heads are fixedly connected to both ends of the tank body, a guide rail is symmetrically fixedly connected to one side of the inner side of the guard plate, both ends of the guide rail are fixedly connected to limit plates, a threaded rod is rotatably connected between the two limit plates, guide rods are symmetrically arranged on the outer side of the threaded rod, a moving plate is threadedly connected to the outer side of the threaded rod, the threaded rod is fixedly connected to the output end of a motor, the motor is fixedly connected to the inner top wall of the guard plate, a corrosion rate detection mechanism is arranged on one side of the moving plate, and the computing chip is electrically connected to the corrosion rate detection mechanism, wherein a corrosion rate calculation module is arranged for calculating the corrosion rate according to parameters collected by the corrosion rate detection mechanism and a preset mathematical model.

Description

Technical Field

[0001] The invention belongs to the technical field of detection equipment for measuring electrical variables, and in particular relates to a corrosion rate detection device for an earth-covered storage tank after cathodic protection. Background Art

[0002] As an important industrial equipment, storage tanks are widely used in the fields of petroleum, chemical industry, etc. In order to prevent accidents such as leakage during the use of storage tanks, cathodic protection technology is usually used to treat the storage tanks for corrosion. Cathodic protection is to apply appropriate current to the surface of the storage tank to inhibit the occurrence of corrosion reactions, thereby achieving the purpose of extending the service life of the storage tank. However, after long-term operation, the surface of the storage tank will still produce varying degrees of corrosion. If it is not discovered in time and effective measures are not taken, it may threaten the safety of the storage tank and cause serious environmental pollution accidents.

[0003] In order to monitor the corrosion status of storage tanks in a timely manner, electrochemical detection technologies such as the potential-shift method and the electrochemical noise method are often used in the existing technologies. Among them, the potential-shift method evaluates the degree of corrosion by detecting the change in corrosion potential on the metal surface, but it is greatly affected by factors such as ambient temperature and humidity, and it is difficult to obtain accurate corrosion indicators. The electrochemical noise method uses the tiny current and potential fluctuation signals generated by the corrosion reaction on the metal surface to analyze the corrosion situation, but the instrument has low sensitivity and cannot monitor subtle corrosion changes. In addition, most of these existing technologies use point-type detection methods, which can only obtain corrosion information on individual parts of the storage tank, and it is difficult to fully reflect the overall corrosion status of the storage tank.

[0004] At the same time, most of the existing detection equipment is installed outside the tank, which makes it difficult to monitor buried or covered tanks in real time. This requires the detection equipment to have certain waterproof, dustproof, pressure-resistant and other characteristics to adapt to the complex underground environment. However, the existing detection equipment is usually large in size, and it is inconvenient to install and maintain, which limits its application in covered tanks.

[0005] Therefore, there is an urgent need for a corrosion rate detection device for earth-covered storage tanks after cathodic protection, which can comprehensively, accurately and in real time monitor the corrosion of the storage tanks and provide technical support for the safety assessment and maintenance of the storage tanks. Summary of the invention

[0006] In view of this, the present invention provides a corrosion rate detection device for earth-covered storage tanks after cathodic protection, which can solve the technical problem that most of the existing technologies adopt point-type detection methods, which can only obtain corrosion information of individual parts of the storage tank and it is difficult to fully reflect the overall corrosion status of the storage tank.

[0007] The present invention is achieved in that:

[0008] The present invention provides a corrosion rate detection device for a covered earth storage tank after cathodic protection, comprising: a tank body, a guard plate, a base, a spherical head, a corrosion rate detection mechanism and a computing chip, wherein the base is symmetrically fixedly connected to the bottom of the tank body on both sides, the spherical heads are fixedly connected to both ends of the tank body, the guard plate is a rectangular parallelepiped structure and a guide rail is symmetrically fixedly connected to one side of the inner side thereof, both ends of the guide rail are fixedly connected to a limiting plate, a threaded rod is rotatably connected between the two limiting plates, guide rods are symmetrically arranged on the outer side of the threaded rod, a moving plate is threadedly connected to the outer side of the threaded rod, the threaded rod is fixedly connected to the output end of a motor, the motor is fixedly connected to the inner top wall of the guard plate, a corrosion rate detection mechanism is arranged on one side of the moving plate, the computing chip is arranged inside the guard plate and electrically connected to the corrosion rate detection mechanism, a corrosion rate calculation module is arranged in the computing chip, and the corrosion rate calculation module is used to calculate the corrosion rate according to the parameters collected by the corrosion rate detection mechanism and a preset mathematical model.

[0009] On the basis of the above technical solution, the corrosion rate detection device for earth-covered storage tank after cathodic protection of the present invention can also be improved as follows:

[0010] Wherein, the corrosion rate calculation module is used to perform the following steps:

[0011] S10, measuring the electrochemical parameters on the surface of the tank through an electrode sensor to obtain a potential value, a current density value, and a metal ion concentration value;

[0012] S20, establishing a corrosion electrochemical model, and calculating the corrosion reaction rate constant according to the potential value, the current density value and the metal ion concentration value;

[0013] S30, obtaining environmental parameters, including soil resistivity, water content, pH value and redox potential;

[0014] S40, establishing an environmental correction coefficient calculation model according to the environmental parameters;

[0015] S50, establishing a corrosion rate calculation model, combining the corrosion reaction rate constant with the environmental correction coefficient;

[0016] S60, calculating the instantaneous corrosion rate according to the corrosion rate calculation model;

[0017] S70, smoothing the instantaneous corrosion rate using a moving time window method to obtain a steady-state corrosion rate;

[0018] S80, calculating the corrosion depth according to the steady-state corrosion rate, and performing corrosion early warning judgment;

[0019] S90. Update the historical database for subsequent corrosion trend analysis.

[0020] The calculation model of the corrosion reaction rate constant is specifically expressed as follows:

[0021] ;

[0022] In the formula, is the corrosion reaction rate constant in millimeters per year; is the pre-exponential factor, and its value range is to ; is the activation energy, expressed in joules per mole; is the gas constant, with a value of 8.314 joules per mole Kelvin; is the absolute temperature in Kelvin; is the current density in amperes per square meter; is the number of electron transfers in the reaction; is the Faraday constant, which is 96485 coulombs per mole.

[0023] The environmental correction coefficient calculation model is specifically expressed as follows:

[0024] ;

[0025] In the formula, is the environmental correction factor; is the soil resistivity in ohm-meter; is the standard soil resistivity, with a value of 1000 ohm-meter; is the soil moisture content, expressed as a percentage; is the standard soil moisture content, which is 20%; is the soil pH; is the standard soil pH, which takes a value of 7; is the redox potential, in volts; is the standard redox potential, which is 0.4 volts; , , , is the weight coefficient, which is obtained through experimental calibration.

[0026] The corrosion rate calculation model is specifically expressed as follows:

[0027] ;

[0028] In the formula, is the corrosion rate in millimeters per year; is the cathodic protection potential, in volts; is the self-corrosion potential, in volts; is the cathodic protection efficiency coefficient, ranging from 0 to 1.

[0029] The calculation of the steady-state corrosion rate adopts the moving time window method, which is specifically expressed as follows:

[0030] ;

[0031] In the formula, For the moment The steady-state corrosion rate of is the time window length; The sampling time interval is in hours.

[0032] The calculation model of the corrosion depth is specifically expressed as follows:

[0033] ;

[0034] In the formula, For the moment The corrosion depth in millimeters; is the integration variable.

[0035] Among them, the weight coefficient , , , The calibration method is:

[0036] 1. Conduct comparative tests under different soil environments;

[0037] 2. Measure the actual corrosion rate of the test sample;

[0038] 3. Use the least squares method to fit the weight coefficient.

[0039] Among them, the corrosion rate detection mechanism includes a threaded sleeve, which has a cylindrical structure and an internal threaded connection with a threaded seat. A telescopic rod is rotatably connected to the center position of the threaded seat. One end of the telescopic rod is fixedly connected to an arc plate. The arc plate has an arc-shaped structure and its inner arc surface matches the outer surface of the tank body. An electrode sensor and a cleaning brush are fixedly connected to the inner side of the arc plate, respectively. The electrode sensor is used to detect the corrosion potential and current density on the surface of the tank body.

[0040] Furthermore, a cathodic protector is fixedly connected to one side of the spherical head, and the cathodic protector is electrically connected to an external power supply through a waterproof cable. The cathodic protector is used to provide cathodic protection current to the tank body. A pipeline is fixedly connected to the lower end of one side of the spherical head, and a gas concentration detector is fixedly connected to one end of the pipeline.

[0041] Furthermore, the guide rod is fixedly connected between the two limit plates, the guide rod is a cylindrical structure with a smooth surface, the movable plate is slidably connected to the outer side of the guide rod, and the movable plate is slidably matched with the guide rod through a built-in bearing.

[0042] Furthermore, sealing strips are provided on both sides of the guard plate. The sealing strips are made of rubber material. The sealing strips are tightly fitted to the outer surface of the tank body. The guard plate is fixed to the ground by fixing bolts. The length of the guard plate matches the length of the tank body.

[0043] Furthermore, a limiting protrusion is arranged on the outer side of the threaded sleeve, and a limiting groove cooperating with the limiting protrusion is opened on the movable plate, and the cooperation between the limiting protrusion and the limiting groove is used to prevent the threaded sleeve from rotating.

[0044] Furthermore, the motor is a stepper motor, the rotation speed of the stepper motor is adjustable, the stepper motor is fixed to the inner wall of the guard plate through a motor seat, the motor seat adopts a shockproof structure, and a coupling is arranged between the output shaft of the stepper motor and the threaded rod.

[0045] Furthermore, the base adopts a reinforced concrete structure, the top surface of the base is provided with anti-slip patterns, the base is fixedly connected to the ground by expansion bolts, and the height of the base is not less than 50 centimeters.

[0046] Furthermore, the cleaning brush includes a brush body and bristles. The brush body is a rectangular structure and the bristles are evenly distributed on its surface. The bristles are made of corrosion-resistant nylon material. The brush body is fixedly connected to the inner surface of the arc plate by screws. The length of the bristles is set according to the roughness of the tank surface.

[0047] Compared with the prior art, the beneficial effects of the corrosion rate detection device after cathodic protection of earth-covered storage tanks provided by the present invention are:

[0048] 1. Comprehensive monitoring: The detection device of the present invention adopts an integrated detection method. By arranging dense detection mechanisms on the surface of the tank, it can comprehensively obtain the corrosion status information of the storage tank, rather than being limited to individual parts. Compared with the point-type detection of the prior art, this can more accurately reflect the overall corrosion status of the storage tank.

[0049] 2. High-precision analysis: The detection device of the present invention combines electrochemical measurement and corrosion model analysis, and can accurately calculate key indicators such as instantaneous corrosion rate, steady-state corrosion rate, and corrosion depth. These indicators not only reflect the current corrosion state, but also predict future corrosion trends, providing a basis for the maintenance of storage tanks. Compared with the existing technology that can only obtain a single corrosion potential or current information, the analysis method of the present invention is more comprehensive and accurate.

[0050] 3. Strong applicability: The detection device of the present invention is specially designed for earth-covered storage tanks. It adopts a waterproof and pressure-resistant mechanical structure, can adapt to complex underground environments, and solves the problem that the existing technology is difficult to monitor buried or earth-covered storage tanks. At the same time, the device is small in size, easy to install and maintain, and provides the possibility of being widely used in practical projects.

[0051] 4. Intelligence: The detection device of the present invention is equipped with a microprocessor chip, which can realize the automatic detection, analysis and early warning functions of the corrosion state. The detection data can be uploaded to the monitoring center in real time to provide decision support for managers. This level of intelligence is higher than the manual detection mode of the existing technology.

[0052] In summary, the corrosion rate detection device for earth-covered storage tanks after cathodic protection proposed in the present invention has obvious improvements in comprehensive monitoring, high-precision analysis, applicability and intelligence, etc., and provides an effective technical means to improve the safety of storage tanks and extend their service life. It solves the technical problem that most of the existing technologies use point-type detection methods, which can only obtain corrosion information of individual parts of the storage tank and it is difficult to fully reflect the overall corrosion status of the storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a schematic structural diagram of a device for detecting the corrosion rate of a soil-covered storage tank after cathodic protection proposed by the present invention;

[0054] Figure 2 is a schematic cross-sectional view of the device;

[0055] Figure 3 is a schematic diagram of the internal structure of the device;

[0056] Figure 4 Schematic diagram of electrode related structure;

[0057] Figure 5 Schematic diagram of the limiting plate structure;

[0058] Figure 6 It is a schematic diagram of the relevant structure of the telescopic rod;

[0059] Figure 7 A flow chart of steps performed for a corrosion rate calculation module;

[0060] Figure 8 The curve of the change of the surface potential of the tank over time is:

[0061] Fig. 9 This is the trend diagram of the corrosion rate of the storage tank;

[0062] Fig.10 This is the trend chart of the corrosion depth change of the tank;

[0063] In the figure: level ground 1, tank body 2, spherical head 3, base 4, cleaning brush 5, cathode protector 6, pipeline 7, gas concentration detector 8, guard plate 9, guide rail 10, limit plate 11, threaded rod 12, guide rod 13, movable plate 14, motor 15, threaded sleeve 16, threaded seat 17, telescopic rod 18, arc plate 19, electrode sensor 20. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0065] like Figure 1-6 As shown, it is a structural schematic diagram of a corrosion rate detection device for a covered earth storage tank after cathodic protection provided by the present invention. The device comprises: a tank body 2 and a guard plate 9, a base 4 is symmetrically fixedly connected to one side of the bottom of the tank body 2, a spherical head 3 is fixedly connected to both ends of the tank body 2, a guide rail 10 is symmetrically fixedly connected to one side of the inner part of the guard plate 9, the length of the guard plate 9 and the internal components are consistent with the length of the covered earth storage tank, and are 76 meters, both ends of the guide rail 10 are fixedly connected to a limit plate 11, a threaded rod 12 is rotatably connected between the two limit plates 11, a guide rod 13 is symmetrically arranged on the outer side of the threaded rod 12, a movable plate 14 is threadedly connected to the outer side of the threaded rod 12, the threaded rod 12 is fixedly connected to the output end of the motor 15, and a corrosion rate detection mechanism is arranged on one side of the movable plate 14. During the installation process, the covered earth storage tank is first positioned and installed, and then the guard plate 9 is installed to the outer side of the covered earth storage tank, and its length is set according to the tank length. By driving the motor 15, the movable plate 14 is moved laterally under the threaded rotation of the tank body 2, and then cooperates with the corrosion rate detection mechanism to perform mobile detection on the surface of the tank body 2. The telescopic rod 18 and the arc plate 19 provided in the corrosion rate detection mechanism are adjustable structures. By rotating the threaded seat 17 provided on the outside of the telescopic rod 18, the telescopic rod 18 pushes the arc plate 19 to fit the surface of the storage tank under the threaded rotation of the threaded sleeve 16 and the threaded seat 17, so that the cleaning brush 5 fits the surface of the storage tank more closely. In this way, the corrosion efficiency can be obtained by measuring parameters such as corrosion potential and current density, so that the number of electrode sensors installed can be reduced by moving and detecting at the same time, so as to reduce costs and improve detection efficiency. It also includes a computing chip, which is arranged inside the guard plate and electrically connected to the corrosion rate detection mechanism. A corrosion rate calculation module is arranged in the computing chip, and the corrosion rate calculation module is used to calculate the corrosion rate according to the parameters collected by the corrosion rate detection mechanism and a preset mathematical model.

[0066] The corrosion rate calculation module is used to perform the following steps:

[0067] S10, measuring the electrochemical parameters on the surface of the tank through an electrode sensor to obtain a potential value, a current density value, and a metal ion concentration value;

[0068] S20, establishing a corrosion electrochemical model, and calculating the corrosion reaction rate constant according to the potential value, the current density value and the metal ion concentration value;

[0069] S30, obtaining environmental parameters, including soil resistivity, water content, pH value and redox potential;

[0070] S40, establishing an environmental correction coefficient calculation model according to the environmental parameters;

[0071] S50, establishing a corrosion rate calculation model, combining the corrosion reaction rate constant with the environmental correction coefficient;

[0072] S60, calculating the instantaneous corrosion rate according to the corrosion rate calculation model;

[0073] S70, smoothing the instantaneous corrosion rate using a moving time window method to obtain a steady-state corrosion rate;

[0074] S80, calculating the corrosion depth according to the steady-state corrosion rate, and performing corrosion early warning judgment;

[0075] S90. Update the historical database for subsequent corrosion trend analysis.

[0076] Preferably, the tank body 2 and the base 4 are both located on top of the flat ground 1 .

[0077] Preferably, a cathode protector 6 is fixedly connected to one side of the spherical head 3 .

[0078] Preferably, a pipeline 7 is fixedly connected to the lower end of one side of the spherical head 3 , and a gas concentration detector 8 is fixedly connected to one end of the pipeline 7 .

[0079] Preferably, the guide rod 13 is fixedly connected between the two limiting plates 11 .

[0080] Preferably, the movable plate 14 is located on the outer side of the guide rod 13 and is slidably connected thereto.

[0081] Preferably, the motor 15 is fixedly connected to the inside of the guard plate 9 .

[0082] Preferably, the corrosion rate detection mechanism includes a threaded sleeve 16, the threaded sleeve 16 is internally threadedly connected to a threaded seat 17, a telescopic rod 18 is rotatably connected to the inside of the threaded seat 17, one end of the telescopic rod 18 is fixedly connected to an arc plate 19, the inner side of the arc plate 19 is respectively fixedly connected to an electrode sensor 20 and a cleaning brush 5, the cleaning brush 5 is driven by a motor 15 and is located on the surface of the tank body 2 for cleaning and sliding, and can wipe off water stains adhered to the surface. The model of the electrode sensor 20 is HeraeusPalnesa2.

[0083] The working principle and use process of this device: When in use, the device drives the moving plate 14 to move horizontally on the surface of the tank body 2 through the motor, and cooperates with the corrosion rate detection mechanism to detect the corrosion rate of the tank surface. The motor 15 drives the threaded rod 12 to rotate, driving the moving plate 14 to move horizontally along the surface of the tank body 2 under the guidance of the guide rod 13. The telescopic rod 18 and the arc plate 19 can fit the surface of the tank body with different curvatures through the adjustment of the threaded seat 17 to ensure that the electrode sensor 20 is in good contact with the surface of the tank body. The cleaning brush 5 moves with the moving plate 14 to wipe the water stains and Impurities ensure the measurement accuracy of the electrode sensor 20. The electrode sensor 20 measures the corrosion potential and current density and other parameters on the tank surface in real time. The host calculates the corrosion rate of the tank based on the measured parameters, combined with the tank material and environmental parameters. The device can reduce the number of electrode sensors installed and reduce costs through mobile detection, while improving detection efficiency. The cleaning brush 5 can remove impurities on the tank surface, ensure the measurement accuracy of the electrode sensor 20, and improve detection accuracy. The device is suitable for earth-covered storage tanks of different shapes and sizes, and can adapt to different corrosion environments.

[0084] The specific implementation of the steps performed by the corrosion rate calculation module is described in detail below:

[0085] The specific implementation of step S10 is as follows: the electrochemical parameters of the tank surface are measured by the electrode sensor to obtain the potential value. , current density value and metal ion concentration First, the surface of the tank is scanned and measured using an electrode sensor to obtain the surface potential value. and current density .Measurement potential value It mainly reflects the change of electrochemical potential during the corrosion reaction, while the current density value It reflects the size of the corrosion current. Secondly, the metal ion concentration at the measuring point is measured using an electrochemical analyzer. These electrochemical parameters are the basic data for subsequent corrosion rate calculation.

[0086] The specific implementation of step S20 is as follows: establish a corrosion electrochemical model, according to the potential value , the current density value And the metal ion concentration value , calculate the corrosion reaction rate constant According to the classic Butler-Volmer equation, the corrosion reaction rate constant It can be expressed as:

[0087] ;

[0088] in, is the pre-exponential factor, and its value range is to ; is the activation energy, expressed in joules per mole; is the gas constant, and its value is Joule per mole Kelvin; is the absolute temperature in Kelvin; is the current density in amperes per square meter; is the number of electron transfers in the reaction; is the Faraday constant, whose value is Coulomb per mole. This model converts the potential value into , current density value and metal ion concentration The corrosion reaction rate constant k is calculated.

[0089] The specific implementation of step S30 is as follows: Obtain environmental parameters, including soil resistivity , water content , pH value and redox potential First, use a soil resistivity meter to measure the soil resistivity. , in ohm-meters. Then, the soil moisture content was measured using a soil moisture detector. , in percentage. Next, use a pH meter to measure the soil pH Finally, the redox potential of the soil was measured using a redox potentiometer. , in volts. These environmental parameters reflect the corrosiveness of the soil and are key factors in the subsequent corrosion rate calculation.

[0090] The specific implementation of step S40 is as follows: according to the environmental parameters, establish an environmental correction coefficient calculation model Environmental Correction Factor It reflects the influence of soil environment on corrosion rate and can be expressed as:

[0091] ;

[0092] in, is the standard soil resistivity, Ohm meter; is the standard soil moisture content, ; is the standard soil pH value. ; is the standard redox potential, volt; , , , is the weight coefficient, which is obtained through experimental calibration. The model can convert the measured environmental parameters into corresponding environmental correction coefficients, providing a basis for the next step of corrosion rate calculation.

[0093] The specific implementation of step S50 is as follows: establish a corrosion rate calculation model, and convert the corrosion reaction rate constant The environmental correction factor Combined. Corrosion rate It can be expressed as:

[0094] ;

[0095] in, is the cathodic protection potential, in volts; is the self-corrosion potential, in volts; is the cathodic protection efficiency coefficient, and its value range is To 1. The model multiplies the corrosion reaction rate constant and the environmental correction coefficient, and takes into account the influencing factors of cathodic protection to obtain the final corrosion rate.

[0096] The specific implementation of step S60 is as follows: Calculate the instantaneous corrosion rate according to the corrosion rate calculation model By using the corrosion reaction rate constant k obtained in step S20 and the environmental correction coefficient obtained in step S40 By substituting the cathodic protection parameters into the corrosion rate calculation model, the instantaneous corrosion rate v at the current moment can be obtained. The instantaneous corrosion rate reflects the real-time corrosion state of the tank surface and provides basic data for subsequent smoothing and corrosion depth calculation.

[0097] The specific implementation of step S70 is as follows: the instantaneous corrosion rate is calculated by using a moving time window method. Smoothing is performed to obtain the steady-state corrosion rate The specific formula of the moving time window method is:

[0098] ;

[0099] in, For the moment The steady-state corrosion rate; is the time window length; is the sampling time interval in hours. This method can effectively filter out instantaneous fluctuations and obtain a more stable corrosion rate trend by averaging the instantaneous corrosion rate within a certain time range.

[0100] The specific implementation of step S80 is as follows: according to the steady-state corrosion rate Calculate corrosion depth , and make corrosion warning judgment. Corrosion depth It can be expressed as:

[0101] ;

[0102] By integrating the steady-state corrosion rate , the corrosion depth at the current moment can be obtained If the corrosion depth If it exceeds a preset threshold, such as 5 mm, a corrosion warning is triggered and protective measures are taken in time.

[0103] The specific implementation of step S90 is as follows: update the historical database for subsequent corrosion trend analysis, and convert the instantaneous corrosion rate v calculated in step S60 and the steady-state corrosion rate v calculated in step S70 into And the corrosion depth calculated in step S80 The data are stored in the historical database in chronological order. These data can be used to analyze the long-term trend of tank corrosion and provide a basis for future maintenance.

[0104] Specifically, the principle of the present invention is:

[0105] 1. Electrochemical parameter detection: The device is equipped with dense electrode sensors on the surface of the tank, which can measure the potential value during the corrosion process in real time. , current density value and metal ion concentration These parameters reflect the kinetics of the corrosion reaction and are the basis for subsequent corrosion rate calculations.

[0106] 2. Calculation of corrosion reaction rate constant: Based on the measured electrochemical parameters and the Butler-Volmer equation, the corrosion reaction rate constant can be calculated. This constant describes the inherent kinetics of the corrosion reaction and is related to factors such as temperature and current density.

[0107] 3. Environmental correction coefficient modeling: In addition to the kinetic characteristics of the corrosion reaction itself, environmental factors such as soil resistivity, water content, pH value and redox potential will also have a significant impact on the corrosion rate. Therefore, the present invention establishes an environmental correction coefficient calculation model , these environmental parameters are converted into corresponding correction coefficients to provide a basis for subsequent corrosion rate calculations.

[0108] 4. Comprehensive calculation of corrosion rate: Finally, the present invention proposes a corrosion rate calculation model, which converts the corrosion reaction rate constant obtained in step 2 into and the environmental correction factor obtained in step 3 Multiply them together and consider the influencing factors of cathodic protection to calculate the instantaneous corrosion rate. By using a moving time window to smooth the instantaneous corrosion rate, the steady-state corrosion rate can be obtained. , providing data support for the calculation and early warning of corrosion depth.

[0109] 5. Intelligent monitoring and early warning: The detection device of the present invention is equipped with a microprocessor chip, which can automatically complete the above-mentioned electrochemical parameter measurement, corrosion rate calculation and other processes, and upload the results to the monitoring center. Once the corrosion depth is detected to exceed the preset threshold, the system will automatically issue an early warning signal to remind the management personnel to take necessary maintenance measures. This intelligent monitoring and early warning function greatly improves the efficiency of tank safety management.

[0110] Through the integration of the above core technologies, the corrosion rate detection device for earth-covered storage tanks after cathodic protection of the present invention can comprehensively, accurately and in real time monitor the corrosion state of the storage tank, providing effective technical support for ensuring the safety of the storage tank and extending its service life. Its innovation is reflected in the full use of electrochemical measurement and corrosion kinetics models to build a complete set of intelligent corrosion state monitoring system, which makes up for the shortcomings of existing technologies in detection accuracy, comprehensiveness and applicability.

[0111] The following is an example of a specific application scenario of the present invention: A steel enterprise has an earth-covered storage tank located in a coastal area, which has been in operation for many years using cathodic protection technology. In order to monitor the corrosion state of the storage tank in real time, the enterprise decided to install and test the corrosion rate detection device for earth-covered storage tanks after cathodic protection proposed by the present invention.

[0112] The storage tank is a cylindrical structure with a diameter of 20 meters, a length of 50 meters, and a buried depth of 5 meters. After a comprehensive inspection of the storage tank, three sets of detection devices of the present invention were installed at the upper, middle and lower positions of the tank surface. Each set of detection devices consists of a tank body, a guard plate, a base, a spherical head, a corrosion rate detection mechanism and a computing chip.

[0113] First, the electrochemical parameters on the tank surface are measured by electrode sensors. Figure 8 As shown in the test results, the potential value of the tank surface The current density varies from -0.85 volts to -0.92 volts. The metal ion concentration fluctuates between 0.12 amperes per square meter and 0.22 amperes per square meter. About 0.05 grams per liter. These parameters reflect that the tank surface is in an active corrosion state.

[0114] Secondly, based on the measured electrochemical parameters, the rate constant of the corrosion reaction is calculated. Assume that the pre-exponential factor Pick ,activation energy for Kilojoules per mole, temperature is 298 Kelvin, the electron transfer number is 2, then we can get:

[0115] mm per year;

[0116] This value shows that under the current corrosive environment conditions, the inherent corrosion reaction rate of the tank surface is relatively fast.

[0117] Next, the environmental parameters of the soil where the tank is located were measured: resistivity for Ohm meter, water content for , pH value for , redox potential for Volts. Substituting these parameters into the environmental correction factor calculation model, we get:

[0118] ;

[0119] The correction factor shows that the current soil environment has a certain accelerating effect on tank corrosion.

[0120] Then, the data obtained in steps 2 and 3 are put into the corrosion rate calculation model, assuming that the cathodic protection potential for Volt, self-corrosion potential for Volt, cathodic protection efficiency coefficient for , the instantaneous corrosion rate is calculated for:

[0121] mm per year;

[0122] The instantaneous corrosion rate reflects the real-time corrosion status of the tank surface at the current moment.

[0123] In order to further improve the stability of corrosion rate prediction, the present invention uses the moving time window method to smooth the instantaneous corrosion rate. Assuming the time window length The sampling time interval is 6. If the time is 2 hours, the steady-state corrosion rate can be calculated. for:

[0124] mm per year;

[0125] By integrating the steady-state corrosion rate , the corrosion depth at the current moment can be obtained for:

[0126] mm;

[0127] Since the corrosion depth has not exceeded the pre-set threshold of 5 mm, the system did not trigger the corrosion warning.

[0128] In order to further analyze the long-term trend of tank corrosion, the detection device of the present invention records the above detection data and stores it in a historical database. Table 1 shows some data within 6 months:

[0129] Table 1 Tank corrosion detection data

[0130]

[0131] From the data in Table 1, it can be seen that as the use time increases, the potential value on the surface of the tank increases. Gradually decreasing the current density and metal ion concentration It also shows an upward trend, indicating that the corrosion problem is becoming increasingly serious. The calculated instantaneous corrosion rate and steady-state corrosion rate It is also increasing, reflecting the increasing degree of corrosion. Fig. 9 As shown in Figure 2, the instantaneous corrosion rate of the tank surface changes with time. and steady-state corrosion rate All of them showed an upward trend, which was consistent with the potential value The downward trend is consistent. Finally, Fig.10 Demonstrating the depth of corrosion in a tank Changes: Clearly shows the depth of corrosion on the tank surface As time goes by, it gradually increases from the initial 0.72 mm to 1.83 mm, which is close to the warning threshold of 5 mm.

[0132] Through the above test data and trend analysis, the following conclusions can be drawn:

[0133] 1. The surface of the tank is in a serious corrosion state, and the corrosion problem is getting worse. The potential value decreases, and the current density and metal ion concentration increase, reflecting that the corrosion reaction is becoming more and more active.

[0134] 2. Both the instantaneous corrosion rate and the steady-state corrosion rate show a continuous upward trend, and the corrosion rate is accelerating. If effective measures are not taken, the service life of the storage tank will be greatly shortened.

[0135] 3. The corrosion depth on the tank surface is close to the warning threshold and is likely to exceed the threshold within the next 6 months. At that time, emergency maintenance measures must be taken to ensure the safe use of the tank.

[0136] Based on the above analysis results, the steel company decided to repair and maintain the storage tank as soon as possible, and at the same time strengthen the daily inspection and data analysis of the detection device of the present invention to provide reliable technical support for the safe operation of the storage tank.

[0137] In general, the corrosion rate detection device for earth-covered storage tanks after cathodic protection proposed in the present invention can comprehensively, accurately and in real time monitor the corrosion state of the storage tanks, providing an effective technical means for ensuring the safety of the storage tanks and extending their service life.

[0138] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A corrosion rate detection device for earth-covered storage tanks after cathodic protection, characterized in that: include: A tank body, a guard plate, a base, a spherical head, a corrosion rate detection mechanism and a computing chip, wherein the base is symmetrically fixedly connected to the two sides of the bottom of the tank body, the two ends of the tank body are fixedly connected to the spherical head, the guard plate is a rectangular structure and one side of the interior is symmetrically fixedly connected to a guide rail, both ends of the guide rail are fixedly connected to a limit plate, a threaded rod is rotatably connected between the two limit plates, guide rods are symmetrically arranged on the outside of the threaded rod, a moving plate is threadedly connected to the outside of the threaded rod, the threaded rod is fixedly connected to the output end of the motor, the motor is fixedly connected to the inner top wall of the guard plate, a corrosion rate detection mechanism is arranged on one side of the moving plate, the computing chip is electrically connected to the corrosion rate detection mechanism, a corrosion rate calculation module is arranged in the computing chip, and the corrosion rate calculation module is used to calculate the corrosion rate according to the parameters collected by the corrosion rate detection mechanism and the preset The corrosion rate is calculated by a mathematical model; the corrosion rate detection mechanism includes a threaded sleeve, the threaded sleeve is in a cylindrical structure and is internally threadedly connected to a threaded seat, a telescopic rod is rotatably connected to the center position of the threaded seat, one end of the telescopic rod is fixedly connected to an arc plate, the arc plate is in an arc structure and its inner arc surface matches the outer surface of the tank body, the inner side of the arc plate is respectively fixedly connected to an electrode sensor and a cleaning brush, the electrode sensor is used to detect the corrosion potential and current density on the surface of the tank body; a cathodic protector is fixedly connected to one side of the spherical head, the cathodic protector is electrically connected to an external power supply through a waterproof cable, the cathodic protector is used to provide a cathodic protection current to the tank body, the lower end of one side of the spherical head is fixedly connected to a pipeline, and one end of the pipeline is fixedly connected to a gas concentration detector; the corrosion rate calculation module is used to perform the following steps: S10, measuring the electrochemical parameters on the surface of the tank through an electrode sensor to obtain a potential value, a current density value, and a metal ion concentration value; S20, establishing a corrosion electrochemical model, and calculating the corrosion reaction rate constant according to the potential value, the current density value and the metal ion concentration value; S30, obtaining environmental parameters, including soil resistivity, water content, pH value and redox potential; S40, establishing an environmental correction coefficient calculation model according to the environmental parameters; S50, establishing a corrosion rate calculation model, combining the corrosion reaction rate constant with the environmental correction coefficient; S60, calculating the instantaneous corrosion rate according to the corrosion rate calculation model; S70, smoothing the instantaneous corrosion rate using a moving time window method to obtain a steady-state corrosion rate; S80, calculating the corrosion depth according to the steady-state corrosion rate, and performing corrosion early warning judgment.

2. The device for detecting the corrosion rate of a soil-covered storage tank after cathodic protection according to claim 1 is characterized in that: The corrosion rate calculation module further includes step S90, updating the historical database for subsequent corrosion trend analysis.

3. The device for detecting the corrosion rate of a soil-covered storage tank after cathodic protection according to claim 2 is characterized in that: The guide rod is fixedly connected between the two limit plates. The guide rod is cylindrical and has a smooth surface. The movable plate is slidably connected to the outer side of the guide rod. The movable plate is slidably matched with the guide rod through a built-in bearing.

4. The device for detecting corrosion rate of earth-covered storage tank after cathodic protection according to claim 3 is characterized in that: Sealing strips are arranged on both sides of the guard plate. The sealing strips are made of rubber material. The sealing strips are tightly fitted to the outer surface of the tank body. The guard plate is fixed to the ground by fixing bolts. The length of the guard plate matches the length of the tank body.

5. The device for detecting corrosion rate of earth-covered storage tank after cathodic protection according to claim 4 is characterized in that: A limiting protrusion is arranged on the outer side of the threaded sleeve, and a limiting groove matched with the limiting protrusion is opened on the movable plate. The cooperation between the limiting protrusion and the limiting groove is used to prevent the threaded sleeve from rotating.

6. The device for detecting the corrosion rate of a soil-covered storage tank after cathodic protection according to claim 5 is characterized in that: The motor is a stepper motor, the rotation speed of the stepper motor is adjustable, the stepper motor is fixed to the inner wall of the guard plate through a motor seat, the motor seat adopts a shockproof structure, and a coupling is arranged between the output shaft of the stepper motor and the threaded rod.

7. The device for detecting corrosion rate of earth-covered storage tank after cathodic protection according to claim 6 is characterized in that: The base adopts a reinforced concrete structure, the top surface of the base is provided with anti-slip patterns, the base is fixedly connected to the ground by expansion bolts, and the height of the base is not less than 50 centimeters.

8. The device for detecting corrosion rate of earth-covered storage tank after cathodic protection according to claim 7 is characterized in that: The cleaning brush includes a brush body and bristles. The brush body is in a rectangular structure and has bristles evenly distributed on its surface. The bristles are made of corrosion-resistant nylon material. The brush body is fixedly connected to the inner surface of the arc plate by screws. The length of the bristles is set according to the roughness of the tank surface.

9. The device for detecting corrosion rate of earth-covered storage tank after cathodic protection according to claim 8, characterized in that: The computing chip is arranged inside the guard plate.

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