CN104846381A - Cathode protection simulation method of sacrificial anode - Google Patents

Abstract

The invention discloses a cathodic protection simulation method for a sacrificial anode, which relates to the technical field of corrosion and protection. The scheme is mainly aimed at soil environments with different characteristics in different regions. The simulation site selects test points with typical regional soil characteristics. The simulation facilities include small Simulate the ground grid, inspection sheet, sacrificial anode, and monitoring device. The monitoring device includes a current input port, a synchronous interrupter, a reference electrode and a cathodic protection potential monitor. The sacrificial anode is connected to the ground grid through a cable, and the key part of the ground grid is set to the ground For the monitoring device, inspection sheets are buried around the ground net, and partly connected to the ground net for reference and comparison. This scheme is simple in construction, easy to test, easy to excavate and sample, and can better reflect the actual corrosion and protection conditions of the substation, and can obtain more comprehensive and real corrosion and protection data, so as to be a cathodic protection for the ground network in a specific soil environment Provide reliable technical support.

Description

A Cathodic Protection Simulation Method for Sacrificial Anodes

technical field

The invention relates to the technical field of corrosion and protection, in particular to a cathodic protection simulation method of a sacrificial anode.

Background technique

With the development of the economy and the progress of the times, people's requirements for the power system are getting higher and higher. In recent years, the power system has been continuously developed in the direction of ultra-high voltage, large capacity and long distance, and the importance of grounding devices to ensure the safe operation of the power grid has become more and more prominent. The grounding grid has been working in the soil environment for a long time. Due to the complex chemical composition of the soil and the different soil physical properties in different regions, the grounding grid will inevitably be damaged due to corrosion. At present, the commonly used grounding materials in my country are carbon steel and galvanized steel, which are severely corroded in acidic soil. In some areas, the ground grid has been severely corroded within a few years, affecting the normal operation of the power system. Since soil corrosion basically belongs to electrochemical corrosion, cathodic protection as an electrochemical anticorrosion method is currently the most effective protection measure. The sacrificial anode method is simple and easy to operate, has a long running time, requires no maintenance, and can reduce grounding resistance, which is conducive to the dissipation of stray current.

The existing cathodic protection technology judges the protection degree of the ground network by measuring the protection current and the protection potential of the ground network. The criteria for judgment are based on past experience. However, the soil environment where the ground grid is buried is different, and the soil resistivity varies greatly. The measured protection current and potential have a large deviation due to the influence of IR drop. This can lead to complete distortion of the measured values and affect the effectiveness of cathodic protection.

Contents of the invention

The technical problem to be solved by the present invention is to provide a cathodic protection simulation method for sacrificial anodes, by adopting more effective grounding grid anti-corrosion measures to achieve the purpose of determining the optimal protection parameters of cathodic protection for different soil characteristics.

In order to achieve the above object, the present invention provides the following technical solutions: a cathodic protection simulation method of sacrificial anode, characterized in that: the cathodic protection simulation method of sacrificial anode includes ground grid and NiP-DLC composite anti-corrosion protective coating, The number of sacrificial anodes connected to the ground grid can be adjusted, and the protection position can be changed. This method establishes simulation facilities for soil environments with different characteristics in different regions. The simulation site selects test points with typical regional soil characteristics. The simulation facilities include small Simulate the ground grid, inspection sheet, sacrificial anode, and monitoring device. The monitoring device includes a current input port, a synchronous interrupter, a reference electrode and a cathodic protection potential monitor. The sacrificial anode is connected to the ground grid through a cable, and the key part of the ground grid is set to the ground As for the monitoring device, inspection sheets are buried around the ground grid, and some parts are connected to the ground grid for reference and comparison. The working process of the sacrificial anode cathodic protection simulation method is as follows:

(1) At the connection between the sacrificial anode and the ground grid and the key positions of the ground grid, the ground is led out through cables, and a ground monitoring device is installed;

(2) The synchronous interrupter in the monitoring device can simultaneously disconnect multiple sacrificial anodes from the ground grid, which is convenient for measuring the power-off potential of the ground grid;

(3) The cathodic protection monitor can measure the input current of the anode and the protection potential of the ground grid and the inspection sheet relative to the copper sulfate reference electrode;

(4) The current input port can simulate the introduction of stray current to study the influence of stray current on the corrosion of the ground grid and the protection degree of the sacrificial anode method;

(5) According to the test results, the size of the protection current can be adjusted reasonably to optimize the protection effect.

The inspection sheet is made of carbon steel and galvanized steel, and part of it is connected to the ground grid. The corrosion of the soil environment to the two materials and the degree of protection of the sacrificial anode method can be compared and analyzed, so as to provide a basis for the analysis and selection of grounding materials that are more suitable for the soil environment.

According to experience, the minimum cathodic protection current density of sacrificial anode in soil is 10~30mA/m ² . Preliminarily determine the minimum current required to protect the ground grid through theoretical calculations, so as to determine the number of sacrificial anodes required and connect them to the ground grid. At the same time, prepare a certain number of spare sacrificial anodes, so as to adjust the size of the protection current according to the needs.

The sacrificial anode connected to the ground grid is first connected in series with a synchronous interrupter for synchronous on-off. Use the cathodic protection potential monitor in the monitoring device to monitor the protection potential of the ground grid. The reading of the potential monitor is basically stable at a value during the power-on time, that is, the power-on potential is obtained, and the potential monitor displays the first value as the power-off potential at the moment of power-off during the power-off time. And through the computer COM serial data communication port, the measurement results are transmitted to the computer for analysis and processing, and the protection effect is verified, and the input current of the sacrificial anode is reasonably optimized.

After the simulation test has been carried out stably for a period of time, the inspection piece can be taken out to observe the corrosion of the inspection piece and analyze the degree of protection of the sacrificial anode method on carbon steel and galvanized steel. Further adjust the protection current by adjusting the number of sacrificial anodes to achieve the best protection effect and determine the optimal protection parameters. Then the simulated ground network can be excavated to analyze the corrosion degree of the ground network, so as to obtain more comprehensive corrosion and protection information, and verify the protection effect of the sacrificial anode method. The sampling cycle of the inspection sheet can generally be set as one year, while the sampling cycle of the ground network can be set as two years. There is a current input port on the simulated ground grid, through which an external current can be fed into the simulated ground grid to simulate the impact of stray current on the corrosion of the ground grid and the degree of protection of the sacrificial anode. This simulation scheme has small construction volume, convenient sampling, and no need for large-scale excavation of substations. And it can flexibly conduct comparative tests according to needs, and it is convenient to monitor and test.

Preferably, the protective coating includes a NiP alloy coating on the ground grid material and a pure carbon diamond-like carbon coating on the NiP alloy coating.

Preferably, the NiP alloy coating is an anti-corrosion coating, and the pure carbon diamond-like coating is a high-hardness anti-oxidation coating.

Preferably, the method for preparing the NiP alloy coating is to deposit a NiP alloy coating on the surface of the grounding grid material by electroless plating.

Preferably, the preparation method of the pure carbon diamond-like carbon coating is to deposit a pure carbon diamond-like carbon coating on the surface of the NiP alloy coating by using an anode layer ion source in a vacuum chamber.

The beneficial effects of adopting the above technical solutions are: the coating of the sacrificial anode cathodic protection simulation method has better wear resistance, corrosion resistance and oxidation resistance, and is environmentally friendly, and a thicker composite coating can be obtained, which can be greatly improved. Significantly extend the service life of the coating and reduce costs. The simulation scheme is simple to construct, easy to test, easy to excavate and sample, and can better reflect the actual corrosion and protection of the substation, and can obtain more comprehensive and real corrosion and protection data, so that It can provide reliable technical support for cathodic protection of ground grid in specific soil environment. Due to the small size of the test piece, the traditional inspection method is difficult to reflect the corrosion status of the macro cell. The simulated ground grid can better simulate the actual corrosion situation of the substation, make up for the deficiency of the inspection sheet method, and help to obtain more comprehensive corrosion information in a specific soil environment.

Description of drawings

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a side view of the cathodic protection simulation method of the sacrificial anode of the present invention.

Among them, 1—ground grid, 2—sacrificial anode, 3—copper sulfate reference electrode, 4—monitoring device, 5—cable, 6—check sheet.

Detailed ways

The preferred implementation of the cathodic protection simulation method for sacrificial anodes of the present invention will be described in detail below in conjunction with the accompanying drawings.

1 shows the specific implementation of the cathodic protection simulation method of the sacrificial anode of the present invention: the cathodic protection simulation method of the sacrificial anode includes a ground grid 1 and a NiP-DLC composite anti-corrosion protective coating, and the sacrificial anode 2 connected to the ground grid 1 The number can be adjusted, and the protection position can be changed. This method establishes simulation facilities for soil environments with different characteristics in different regions. The simulation site selects test points with typical regional soil characteristics. The simulation facilities include small simulated ground grids 1, inspection sheets 6. The sacrificial anode 2 and the monitoring device 4, the monitoring device 4 includes a current input port, a synchronous interrupter, a reference electrode and a cathodic protection potential monitor, the sacrificial anode 2 is connected to the ground grid 1 through a cable 5, and the key parts of the ground grid 1 are set In the ground monitoring device, an inspection piece is buried around the ground grid 1 and partly connected to the ground grid 1 for reference and comparison. The working process of the cathodic protection simulation method of the sacrificial anode is as follows:

(1) At the connection between the sacrificial anode 2 and the ground grid 1 and the key positions of the ground grid 1, the ground is led out through the cable 5, and the ground monitoring device 4 is installed;

(2) The synchronous interrupter in the monitoring device 4 can synchronously disconnect the connection between multiple sacrificial anodes 2 and the ground grid 1, which is convenient for measuring the power-off potential of the ground grid 1;

(3) The cathodic protection monitor can measure the input current of the anode and the protective potential of the ground grid 1 and the inspection sheet 6 relative to the copper sulfate reference electrode 3;

(4) The current input port can simulate the introduction of stray current to study the influence of stray current on the corrosion of the ground grid and the protection degree of the sacrificial anode method;

(5) According to the test results, the size of the protection current can be adjusted reasonably to optimize the protection effect.

The protective coating includes a NiP alloy coating on the material of the grounding grid 1 and a pure carbon diamond-like carbon coating on the NiP alloy coating. The NiP alloy coating is an anti-corrosion coating, and the pure carbon diamond-like coating is a high-hardness anti-oxidation coating. The preparation method of the NiP alloy coating is to deposit the NiP alloy coating on the surface of the grounding grid material by electroless plating. The preparation method of the pure carbon diamond-like carbon coating is to deposit the pure carbon diamond-like carbon coating on the surface of the NiP alloy coating by using an anode layer ion source in a vacuum chamber.

Carbon steel and galvanized steel are selected as the materials for the simulated ground grid 1. As shown in Figure 1, carbon is used on one side of the sacrificial anode 2 access point and galvanized steel on the other side. In the middle, three anode access points are set at the closest point, the middle point and the farthest point from the sacrificial anode 2 . The effect of different access positions of sacrificial anode 2 on the degree of protection of ground grid 1 is compared and studied.

Magnesium alloy is selected as the sacrificial anode 2, and 5 sacrificial anodes 2 are set, 3 of which are connected to the ground grid 1, and 2 are used as spares, which can be used to adjust the protection current according to the actual protection effect. A ground test pile is installed at the anode end, and the cathodic protection monitor is used to monitor the magnitude of the protection current.

Buried a copper sulfate reference electrode 3 at a key position of the ground grid 1, set test piles on the ground, and used a cathodic protection monitor to check the protection potential of each position of the ground grid 1 relative to the reference electrode 3.

An inspection piece 6 is arranged on the periphery of the ground grid, half of which is connected to the potential of the cathodic protection inspection piece 6, and half of which is not connected to the ground grid 1 as a weightlessness inspection piece 6. The excavation inspection cycle of the inspection sheet 6 can be set as one year, and the inspection cycle of the ground network 1 is two years.

The ground grid 1 is also provided with a current input port in the test pile. After optimizing the protection parameters of sacrificial anode 2, the external current can be passed through this port to study the influence of stray current on the protection degree of ground grid 1. At the same time, a stray current tester is connected to the current input port to monitor the magnitude of the stray current.

The above are only preferred embodiments of the present invention, and it should be pointed out that for those skilled in the art, without departing from the creative concept of the present invention, some modifications and improvements can also be made, and these all belong to the scope of the present invention. protected range.

Claims (5)

1. the galvanic protection analogy method of a sacrificial anode, it is characterized in that: described method comprises earth mat and NiP-DLC composite corrosion-proof erosion protective coating, the number of the sacrificial anode of access earth mat can adjust, and protective position can convert, simulation facility is set up to the edatope of different qualities in different zones, simulation place election has the test point of representative region soil characteristic, simulation facility comprises small-sized simulation earth mat, coupon, sacrificial anode, and monitoring device, described monitoring device comprises current input terminal mouth, sync break device, reference electrode and cathodic protection potential monitor, sacrificial anode is connected to earth mat by cable, earth mat key position arranges ground monitoring device, coupon is buried underground around earth mat, and part is connected with earth mat, with reference contrast, the working process of the galvanic protection analogy method of this sacrificial anode is as follows:

(1) all draw ground by cable at the key position of sacrificial anode and earth mat junction and earth mat, and establish ground monitoring device;

(2) in monitoring device, sync break device synchronously can disconnect the connection of multiple sacrificial anode and earth mat, is convenient to measure earth mat switch-off potential;

(3) cathodic protection monitoring instrument can measure the received current of anode and earth mat and the coupon protection potential relative to copper sulfate reference electrode;

(4) current input terminal mouth can simulate importing stray current, and research stray current is on the impact of Grounding Grid and sacrificial anode protection protection degree;

(5) according to test result can Reasonable adjustment protection protective current size, to optimize protected effect.

2. the galvanic protection analogy method of sacrificial anode according to claim 1, is characterized in that: described protective coating comprises the NiP alloy coat overlayed on ground net material and the pure carbon diamond-like coating overlayed on NiP alloy coat.

3. the galvanic protection analogy method of sacrificial anode according to claim 2, is characterized in that: described NiP alloy coat is corrosion-resistant coating, and pure carbon diamond-like coating is high-hardness antioxidation coating.

4. the galvanic protection analogy method of sacrificial anode according to claim 3, is characterized in that: described NiP alloy coat preparation method is for adopting electroless plating at ground net material surface deposition NiP alloy coat.

5. the galvanic protection analogy method of sacrificial anode according to claim 3, is characterized in that: pure carbon diamond-like coating preparation method for adopt anode layer ion source at the pure carbon diamond-like coating of NiP alloy coat surface deposition in vacuum chamber.