An apparatus for simulating direct current interference corrosion and an experimental method

Abstract

The application discloses a kind of simulated direct current interference corrosion device and experimental method, wherein, simulated direct current interference corrosion device includes: pipeline;The inlet and outlet of pipeline are connected with liquid storage tank respectively;Liquid storage tank is connected with gas adjusting mechanism and temperature adjusting mechanism;Pipeline has insulated pipe section, and a plurality of corrosion test pieces are installed in insulated pipe section;Corrosion test piece is connected with the anode of power supply by current voltage adjusting mechanism, and the non-insulated pipe section of pipeline is connected with the cathode of power supply by current voltage adjusting mechanism;Flow rate adjusting mechanism is arranged on pipeline.Employed method can only give comprehensive result when detecting corrosion situation and interference protection effect of pipeline inner wall in the prior art, single factor causing corrosion cannot be detected, evaluated and distinguished, single factor variable causing corrosion cannot be controlled alone, and working condition of pipeline under the influence of different factors cannot be simulated, leading to the problem that corrosion situation caused by single factor is difficult to evaluate.

Description

Technical Field

[0001] This invention relates to the field of oilfield surface engineering, specifically to a device and experimental method for simulating DC interference corrosion. Background Technology

[0002] Interference corrosion is a significant factor contributing to the corrosion of metal pipelines in oil fields. To mitigate DC interference corrosion, it is necessary to detect the interference and implement protective measures. Currently, the commonly used method for detecting DC interference corrosion and evaluating the effectiveness of interference protection in oil field pipelines is the "potential comparison analysis method." This method analyzes and evaluates the degree of DC interference corrosion and the effectiveness of DC interference protection by examining changes in the pipeline's potential relative to ground. While highly efficient and predictive, this approach is indirect and cannot perform individual testing and evaluation of each of the main factors causing interference corrosion.

[0003] Another method is the "direct defect evaluation method," which directly tests and evaluates the DC interference corrosion defects that appear on site. This method can only be used after DC interference corrosion has occurred and developed to a certain extent. Although it is more intuitive, it has a lag effect and low evaluation efficiency.

[0004] The data obtained from the two methods described above can only provide a comprehensive result and cannot be used to detect and evaluate individual factors causing DC interference corrosion. In reality, DC interference corrosion has multiple influencing factors, including interference corrosion voltage, interference corrosion current, distance from the interference source, medium flow velocity, relative flow direction of the medium and interference current, medium temperature, and concentration of oxidizing gases in the medium. These factors are usually difficult to distinguish and control individually, and the problem of difficulty in evaluating these factors individually has not yet been solved.

[0005] Therefore, in order to promote the effective implementation of DC interference corrosion testing and evaluation, it is necessary to evaluate multiple interference corrosion factors separately and simulate the DC interference corrosion of pipelines under the influence of different factors. This DC interference corrosion simulation problem urgently needs to be solved. Summary of the Invention

[0006] In view of this, the present invention provides a device and experimental method for simulating DC interference corrosion, in order to solve the problem that the methods used in the past for detecting the corrosion of the inner wall of pipelines and the effectiveness of interference protection can only give comprehensive results, but cannot detect, evaluate and distinguish individual factors that cause corrosion, cannot control individual variables that cause corrosion individually, and cannot simulate the working conditions of pipelines under the influence of different factors, which makes it difficult to evaluate the corrosion caused by individual factors.

[0007] In a first aspect, the present invention provides a device for simulating DC interference corrosion, comprising: a pipeline;

[0008] The inlet and outlet of the pipeline are respectively connected to a liquid storage tank, which contains a medium;

[0009] The storage tank is connected to a gas regulating mechanism for injecting oxidizing gas into the medium and for detecting and regulating the concentration of oxidizing gas in the medium.

[0010] The storage tank is connected to a temperature regulating mechanism for detecting and regulating the temperature of the medium.

[0011] The pipeline has an insulated pipe section, and several corrosion test pieces are installed along the pipeline axis inside the insulated pipe section.

[0012] The corrosion test piece is connected to the positive terminal of the power supply through a current and voltage adjustment mechanism, and the non-insulated pipe section is connected to the negative terminal of the power supply through the current and voltage adjustment mechanism.

[0013] The pipeline is equipped with a flow rate regulating mechanism for detecting and controlling the flow rate of the medium.

[0014] Preferably, the gas regulating mechanism includes: an oxidation inlet pipe, a displacement inlet pipe, a gas concentration detection unit, and an exhaust pipe;

[0015] One end of the oxidation inlet pipe is connected to an oxidizing gas source, and the other end is connected to the liquid storage tank;

[0016] One end of the displacement air inlet pipe is connected to the displacement gas source, and the other end is connected to the liquid storage tank.

[0017] The gas concentration detection unit is connected to the liquid storage tank and is used to detect the concentration of oxidizing gas in the medium inside the liquid storage tank;

[0018] The exhaust pipe is connected to the liquid storage tank and is located at the top of the liquid storage tank.

[0019] Preferably, it further includes: a pressure gauge;

[0020] The pressure gauge is fixed to the top of the liquid storage tank and is connected to the inside of the liquid storage tank to detect the pressure inside the liquid storage tank.

[0021] Preferably, the temperature regulating mechanism includes: a heating thermostat, an electric heating rod, and a temperature sensor;

[0022] The electric heating rod is installed inside the liquid storage tank, and the electric heating rod is connected to the heating temperature controller via a circuit;

[0023] The heating temperature controller is connected to a power source and is used to control the heating temperature of the electric heating rod.

[0024] The temperature sensor is connected to both the liquid storage tank and the heating temperature controller.

[0025] Preferably, the current and voltage adjustment mechanism includes: an adjustable resistor, an ammeter, and a voltmeter;

[0026] The adjustable resistor is connected to the power supply, and the line connecting the adjustable resistor and the negative terminal of the power supply is a non-insulated pipe section.

[0027] The sliding end of the adjustable resistor is connected to the corrosion test piece via an ammeter;

[0028] One end of the voltmeter is connected to the circuit between the adjustable resistor and the negative terminal of the power supply, and the other end is connected to the circuit between the adjustable resistor and the ammeter.

[0029] Preferably, the flow rate regulating mechanism includes: a circulating pump and a flow meter;

[0030] The circulating pump is installed on the pipeline and is used to control the flow rate of the medium in the pipeline;

[0031] The flow meter is installed inside the pipe and is used to detect the flow rate of the medium inside the pipe.

[0032] Preferably, the pipe is U-shaped, with the ends of the two arms of the U-shape being open and respectively connected to the liquid storage tank;

[0033] The insulating pipe section is located on each of the two arms of the U-shaped pipe.

[0034] Secondly, the present invention provides a method for simulating DC interference corrosion experiments, comprising the following steps:

[0035] The gas regulating mechanism is activated to inject oxidizing gas into the medium in the storage tank, and the real-time concentration of oxidizing gas in the medium is detected. If the real-time concentration is not equal to the preset concentration, the gas regulating mechanism is used to adjust the real-time concentration of oxidizing gas in the medium to make it equal to the preset concentration.

[0036] The temperature regulation mechanism is activated to detect the real-time temperature of the medium in the storage tank. If the real-time temperature is not equal to the preset temperature, the temperature regulation mechanism is used to adjust the real-time temperature of the medium to make it equal to the preset temperature.

[0037] The power is turned on, and the current is transmitted to the pipeline and corrosion test piece through the current and voltage adjustment mechanism. The current and voltage adjustment mechanism detects the real-time voltage and current values ​​transmitted to the pipeline and corrosion test piece. If the real-time voltage and current values ​​are not equal to the preset voltage and current values, the current and voltage adjustment mechanism is used to adjust the real-time voltage and current values ​​to make them equal to the preset voltage and current values.

[0038] When the medium in the storage tank enters the pipeline, the flow rate regulation mechanism is activated to detect the real-time flow rate of the medium in the pipeline. If the real-time flow rate is not equal to the preset flow rate, the flow rate regulation mechanism is used to adjust the real-time flow rate of the medium in the pipeline to make it equal to the preset flow rate.

[0039] After the predetermined time has elapsed, the corrosion test piece is removed, and the simulated DC interference corrosion experiment is completed.

[0040] The present invention has the following beneficial effects:

[0041] This invention provides a device and method for simulating DC interference corrosion. It adjusts the concentration of oxidizing gases in the pipeline medium using a gas regulating mechanism; regulates the medium temperature using a temperature regulating mechanism; adjusts the interference corrosion voltage and current applied to the corrosion test piece using a current and voltage regulating mechanism; and regulates the flow velocity of the medium in the pipeline using a flow velocity regulating mechanism. This allows for accurate simulation of pipeline operating conditions and control over individual factors causing corrosion. It solves the problem that previous methods for detecting corrosion on pipeline inner walls and the effectiveness of interference protection could only provide comprehensive results, failing to detect, evaluate, or differentiate individual factors causing corrosion, unable to control individual corrosion-causing variables individually, and unable to simulate pipeline operating conditions under different influences, leading to difficulties in evaluating corrosion caused by individual factors. Attached Figure Description

[0042] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0043] Figure 1 This is a schematic diagram of the structure of a simulated DC interference corrosion device according to an embodiment of the present invention.

[0044] In the diagram, 1-Stable DC power supply, 2-Sliding rheostat, 3-Voltmeter, 4-Ammeter, 6-Corrosion test piece, 7-Insulating pipe section, 8-Test piece clamp, 10-Metal pipe section, 11-Storage tank, 12-Circulating pump, 13-Flow meter, 15-Heating thermostat, 16-Electric heating rod, 17-Temperature sensor, 18-Oxidation inlet pipe, 19-Displacement inlet pipe, 20-Exhaust pipe, 21-Gas concentration detector, 22-Pressure gauge. Detailed Implementation

[0045] The present invention will now be described based on embodiments, but it is worth noting that the present invention is not limited to these embodiments. In the following detailed description of the invention, certain specific details are described in detail. However, those skilled in the art will fully understand the invention for the parts not described in detail.

[0046] Furthermore, those skilled in the art should understand that the accompanying drawings are provided only to illustrate the purpose, features, and advantages of the present invention, and are not actually drawn to scale.

[0047] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0048] Figure 1 This is a schematic diagram of a simulated DC interference corrosion device according to an embodiment of the present invention. Figure 1 As shown, a simulated DC interference corrosion device includes: a pipeline; the inlet and outlet of the pipeline are respectively connected to a storage tank 11, which contains a medium; the storage tank 11 is connected to a gas regulating mechanism for injecting oxidizing gas into the medium and detecting and regulating the concentration of oxidizing gas in the medium; the storage tank 11 is connected to a temperature regulating mechanism for detecting and regulating the temperature of the medium; the pipeline has an insulated pipe section 7, and several corrosion test pieces 6 are installed along the axial direction of the pipeline in the insulated pipe section 7; the corrosion test pieces 6 are connected to the positive terminal of a power supply through a current and voltage regulating mechanism, and the non-insulated pipe section is connected to the negative terminal of the power supply through the current and voltage regulating mechanism; a flow rate regulating mechanism for detecting and controlling the flow rate of the medium is provided on the pipeline.

[0049] In this embodiment of the invention, the pipeline is a simulated metal pipeline used in actual production. The power source is a constant current and voltage DC power supply 1. The negative terminal of the power supply is connected to the non-insulated part of the pipeline, namely the metal pipe section 10, via a current and voltage adjustment mechanism, simulating the part of the pipeline subjected to cathodic protection in actual operation. Several corrosion test pieces 6 are respectively fixed inside the insulating pipe section 7 by test piece clamps 8. The insulating pipe section 7 is connected to the metal pipe section 10 via an insulating flange, and the insulating pipe section 7 serves to insulate the corrosion test pieces 6 from the metal pipe section 10.

[0050] The corrosion test piece 6 is connected to the positive terminal of the power supply via a current and voltage adjustment mechanism. The corrosion test piece 6 simulates the inner metal wall of a pipe section not subjected to cathodic protection. During the simulated DC interference corrosion experiment, the gas regulation mechanism is first activated to inject oxidizing gas into the medium. The gas regulation mechanism detects the real-time concentration of the oxidizing gas in the medium. If the real-time concentration does not meet the preset concentration, the mechanism is adjusted until the oxidizing gas concentration meets the preset concentration required for the experiment. The medium in the storage tank 11 is water.

[0051] The temperature regulation mechanism is activated to detect the real-time temperature of the medium in the storage tank 11. If the real-time temperature of the medium is not equal to the temperature of the working condition to be simulated in the experiment, i.e. the preset temperature, the temperature of the medium is adjusted by the temperature regulation mechanism to meet the temperature required for the experiment.

[0052] A first valve is installed on the pipeline near the liquid storage tank 11. When the temperature of the medium and the concentration of oxidizing gas in the liquid storage tank 11 meet the requirements, the valve is opened, and the medium in the liquid storage tank 11 enters the pipeline.

[0053] After the medium enters the pipeline, the power is turned on, and the current is transmitted to the metal pipe section 10 and the corrosion test piece 6 through the current and voltage regulation mechanism. A circuit is formed between the metal pipe section 10, the medium, and the corrosion test piece 6. After energization, the metal pipe section 10 connected to the current and voltage regulation mechanism is cathodically protected, while the corrosion test piece 6 is not cathodically protected. Because the medium is charged, it will cause interference and corrosion to the corrosion test piece 6. The current and voltage regulation mechanism can detect the real-time voltage and current values ​​transmitted to the pipeline and the corrosion test piece 6, and adjust these values ​​to equal the preset voltage and current values ​​required by the experiment.

[0054] The flow rate adjustment mechanism is activated. The flow rate adjustment mechanism detects whether the real-time flow rate of the medium in the pipeline meets the preset flow rate required for the experiment. If it does not meet the preset flow rate, the flow rate adjustment mechanism will adjust the real-time flow rate of the medium in the pipeline to make it equal to the preset flow rate.

[0055] In the experiment, by setting and adjusting multiple factors that interfere with corrosion, including the concentration of oxidizing gas in the medium, the temperature of the medium, the flow rate of the medium, the interference corrosion voltage, and the interference corrosion current, each factor can meet the predetermined experimental conditions. After a predetermined time, the corrosion test piece 6 is taken out, and the degree of corrosion of the corrosion test piece 6 is observed and evaluated. Thus, the interference corrosion of the corrosion test piece 6 can be evaluated based on the changes of different influencing factors.

[0056] The number of corrosion test pieces 6 is at least 2. In the embodiment, 5 corrosion test pieces 6 are set inside each insulating pipe section 7. The 5 corrosion test pieces 6 are installed at equal distances along the axial direction of the insulating pipe section 7 inside the pipe, that is, the pipe is installed at equal distances along the axial direction.

[0057] Among the factors affecting corrosion is the distance from the interference source. The distance from the interference source is determined by the different distances between the cathodic-protected metal pipe section 10 and the five corrosion test pieces 6 within the insulated pipe section 7. Experiments show that the corrosion test pieces 6 (the unprotected pipe section) experience varying degrees of interference corrosion when their distance from the interference source (the cathodic-protected pipe section) differs. Generally, the greater the distance from the interference source, the weaker the interference corrosion.

[0058] In this invention, the gas regulating mechanism includes: an oxidation inlet pipe 18, a displacement inlet pipe 19, a gas concentration detection unit, and an exhaust pipe 20; one end of the oxidation inlet pipe 18 is connected to an oxidizing gas source, and the other end is connected to a liquid storage tank 11; one end of the displacement inlet pipe 19 is connected to a displacement gas source, and the other end is connected to the liquid storage tank 11; the gas concentration detection unit is connected to the liquid storage tank 11 and is used to detect the concentration of oxidizing gas in the medium inside the liquid storage tank 11; the exhaust pipe 20 is connected to the liquid storage tank 11 and is located at the top of the liquid storage tank 11.

[0059] In this embodiment of the invention, one end of the oxidation inlet pipe 18 is connected to an oxidizing gas source, and the other end is inserted into the medium inside the storage tank 11 from the top; one end of the displacement inlet pipe 19 is connected to a displacement gas source, and the other end is inserted into the medium inside the storage tank 11 from the top; the exhaust pipe 20 is located at the top of the storage tank 11, and there is a certain distance between the bottom opening of the exhaust pipe 20 and the highest liquid level of the medium inside the storage tank 11. A second valve is provided on the oxidation inlet pipe 18, a third valve is provided on the displacement inlet pipe 19, and a fourth valve is provided on the exhaust pipe 20.

[0060] During the experiment, the second valve on the oxidation inlet pipe 18 is opened, and the oxidizing gas is released into the medium in the storage tank 11 through the oxidation inlet pipe 18, causing the concentration of the oxidizing gas in the medium to gradually increase. At this time, the increasing concentration of the oxidizing gas in the medium is detected by the gas concentration detection unit, i.e., the real-time concentration. When the real-time concentration equals the preset concentration, the second valve is closed. The oxidizing gas can be dissolved oxygen.

[0061] If the real-time concentration of oxidizing gas in the medium exceeds the preset concentration, the third valve on the displacement inlet pipe 19 and the fourth valve on the exhaust pipe 20 need to be opened to allow displacement gas to be released into the medium through the displacement inlet pipe 19, thereby displacing the dissolved oxidizing gas in the medium. The displaced oxidizing gas rises to the top space inside the storage tank 11 and is then discharged to the external environment through the exhaust pipe 20. The displacement gas can be nitrogen. The oxidizing gas source is connected to the oxidizing gas source via the oxidizing inlet pipe 18, and the displacement inlet pipe 19 is connected to the displacement gas source. Together with the exhaust pipe 20, this achieves quantitative control of the oxidizing gas concentration in the medium. The gas concentration detection unit includes a gas concentration detector 21, which is fixed to the top of the storage tank 11. The probe of the gas concentration detector 21 is inserted into the medium to detect the concentration of oxidizing gas in the medium.

[0062] The invention also includes a pressure gauge 22; the pressure gauge 22 is fixed to the top of the liquid storage tank 11 and communicates with the inside of the liquid storage tank 11, and is used to detect the pressure inside the liquid storage tank 11.

[0063] In this embodiment of the invention, pressure gauge 22 is used to detect the pressure exerted on the storage tank 11 by both gas and liquid. Besides factors such as the temperature and flow rate of the medium, pressure is also a factor affecting corrosion. Pressure changes within the storage tank 11 also affect the corrosion condition of the corrosion test piece 6. The pressure value detected by pressure gauge 22 within the storage tank 11 will be used for subsequent evaluation of the corrosion condition of the corrosion test piece 6.

[0064] In this invention, the temperature regulation mechanism includes: a heating temperature controller 15, an electric heating rod 16, and a temperature sensor 17; the electric heating rod 16 is installed inside the liquid storage tank 11, and the electric heating rod 16 is connected to the heating temperature controller 15 through a circuit; the heating temperature controller 15 is connected to a power source, and the heating temperature controller 15 is used to control the heating temperature of the electric heating rod 16; the temperature sensor 17 is connected to both the liquid storage tank 11 and the heating temperature controller 15.

[0065] In this embodiment of the invention, during the experiment, the temperature sensor 17 and the heating temperature controller 15 are activated. The temperature sensor 17 detects the real-time temperature of the medium in the storage tank 11 and transmits it to the heating temperature controller 15. When the real-time temperature of the medium is lower than the preset temperature required for the experiment, the heating temperature controller 15 controls the power supply to be turned on and transmits current to the electric heating rod 16, so that the electric heating rod 16 heats up to heat the medium. When the temperature sensor 17 detects that the real-time temperature of the medium has reached the preset temperature required for the experiment, the heating temperature controller 15 controls the power supply to be turned off and the electric heating rod 16 stops heating.

[0066] In this invention, the current and voltage adjustment mechanism includes: an adjustable resistor, an ammeter 4, and a voltmeter 3; the adjustable resistor is connected to a power source, and the line between the adjustable resistor and the negative terminal of the power source is connected to a non-insulated pipe section of a conduit; the sliding end of the adjustable resistor is connected to the corrosion test piece 6 through the ammeter 4; one end of the voltmeter 3 is connected to the line between the adjustable resistor and the negative terminal of the power source, and the other end is connected to the line between the adjustable resistor and the ammeter 4.

[0067] In this embodiment of the invention, the adjustable resistor is a sliding rheostat 2, which is connected to a power supply to form a circuit. Each corrosion test piece 6 is connected to a sliding rheostat 2, an ammeter 4, and a voltmeter 3. Each corrosion test piece 6 is connected to the sliding terminal of a sliding rheostat 2 through a corresponding ammeter 4. One end of each voltmeter 3 is connected to the circuit between the corresponding sliding rheostat 2 and the negative terminal of the power supply, and the other end is connected to the circuit between the sliding rheostat 2 and the ammeter 4. The circuit between the sliding rheostat 2 and the negative terminal of the power supply is connected to the metal pipe section 10 of the pipeline.

[0068] During the experiment, the power switch is turned on, and current is transmitted to the metal pipe section 10 and the corrosion test piece 6 through the sliding rheostat 2, thereby forming cathodic protection for the metal pipe section 10. The ammeter 4 and voltmeter 3 detect the real-time current and voltage values ​​transmitted to the metal pipe section 10 and the corrosion test piece 6. If the real-time current and voltage values ​​do not meet the preset current and voltage values ​​required by the experiment, the position of the slider of the sliding rheostat 2 is adjusted to change the current and voltage values ​​transmitted to the metal pipe section 10 and the corrosion test piece 6 until the real-time current and voltage values ​​are equal to the preset current and voltage values, respectively.

[0069] In this invention, the flow rate regulating mechanism includes a circulating pump 12 and a flow meter 13; the circulating pump 12 is installed on the pipeline and is used to control the flow rate of the medium in the pipeline; the flow meter 13 is installed inside the pipeline and is used to detect the flow rate of the medium in the pipeline.

[0070] In this embodiment of the invention, the circulating pump 12 and the flow meter 13 are installed in the metal pipe section 10 of the pipeline. During the experiment, when the medium in the storage tank 11 enters the pipeline, the flow meter 13 can detect the real-time flow velocity of the medium in the pipeline. If the real-time flow velocity is less than the preset flow velocity required for the experiment, the circulating pump 12 is started to increase the flow velocity of the medium in the pipeline. The impeller rotation speed of the circulating pump 12 is gradually increased, thereby gradually increasing the flow velocity of the medium in the pipeline until the real-time flow velocity of the medium equals the preset flow velocity. In addition to increasing the flow velocity of the medium, the circulating pump 12 is also used to change the flow direction of the medium in the pipeline. When the experiment requires the medium to flow in the opposite direction to observe the corrosion state of the corrosion specimen 6, the flow direction of the medium can be changed by changing the rotation direction of the impeller of the circulating pump 12.

[0071] In this invention, the pipe is U-shaped, with the ends of the two arms of the U-shape being open and connected to the liquid storage tank 11 respectively; the two arms of the U-shape of the pipe each have an insulating pipe section 7.

[0072] In this embodiment of the invention, insulating pipe sections 7 are respectively installed on the two arms of the U-shape of the pipeline. Five corrosion test pieces 6 are installed inside each of the two insulating pipe sections 7, for a total of ten corrosion test pieces 6. These ten test pieces 6 are connected to the adjustable resistors of corresponding current and voltage adjustment mechanisms via circuits. The insulating pipe sections 7 on the two arms of the U-shape of the pipeline are used so that, during the experiment, when the medium in the storage tank 11 enters the pipeline, the openings at the ends of the U-shape are the inlet and outlet of the medium, respectively. After the circulation pump 12 is started, the medium flows in opposite directions within the two insulating pipe sections 7. That is, the medium in one insulating pipe section 7 flows from left to right, while the medium in the other insulating pipe section 7 flows from right to left. This allows for simultaneous testing of the interference corrosion influencing factors caused by the medium flowing in different directions, reducing the number of experiments and the time required.

[0073] The present invention also provides a method for simulating DC interference corrosion experiment, including the following steps: Step 1: control the gas regulating mechanism to start injecting oxidizing gas into the medium in the storage tank 11, and detect the real-time concentration of oxidizing gas in the medium. If the real-time concentration is not equal to the preset concentration, adjust the real-time concentration of oxidizing gas in the medium through the gas regulating mechanism to make it equal to the preset concentration.

[0074] In this embodiment of the invention, during the experiment, the second valve on the oxidation inlet pipe 18 is opened, and the oxidizing gas is released into the medium of the storage tank 11 through the oxidation inlet pipe 18. The real-time concentration of the oxidizing gas in the medium is detected by the gas concentration detection unit, and the second valve is closed when the real-time concentration is equal to the preset concentration.

[0075] If the real-time concentration of oxidizing gas in the medium exceeds the preset concentration, the third valve on the displacement inlet pipe 19 and the fourth valve on the exhaust pipe 20 are opened, allowing the displacement gas to be released into the medium through the displacement inlet pipe 19, thereby displacing the dissolved oxidizing gas in the medium. The displaced oxidizing gas rises to the top space inside the liquid storage tank 11 and is then discharged to the external environment through the exhaust pipe 20. If the gas concentration detection unit detects that the real-time concentration of oxidizing gas in the medium has decreased to the preset concentration, the third and fourth valves are closed.

[0076] Step 2: The temperature regulation mechanism is activated to detect the real-time temperature of the medium in the storage tank 11. If the real-time temperature is not equal to the preset temperature, the temperature regulation mechanism is used to adjust the real-time temperature of the medium to make it equal to the preset temperature.

[0077] In this embodiment of the invention, the temperature sensor 17 and the heating temperature controller 15 are activated. The temperature sensor 17 detects the real-time temperature of the medium in the storage tank 11 and transmits it to the heating temperature controller 15. When the heating temperature controller 15 determines that the real-time temperature of the medium is lower than the preset temperature required for the experiment, the heating temperature controller 15 controls the power supply to start and transmit current to the electric heating rod 16, so that the electric heating rod 16 heats up to heat the medium. When the temperature sensor 17 detects that the real-time temperature of the medium is equal to the preset temperature, the heating temperature controller 15 controls the power supply to turn off, and the electric heating rod 16 stops heating.

[0078] Step 3: Turn on the power supply so that the current is transmitted to the pipeline and corrosion test piece 6 through the current and voltage adjustment mechanism. The current and voltage adjustment mechanism detects the real-time voltage and current values ​​transmitted to the pipeline and corrosion test piece 6. If the real-time voltage and current values ​​are not equal to the preset voltage and current values, the current and voltage adjustment mechanism is used to adjust them so that the real-time voltage and current values ​​are equal to the preset voltage and current values.

[0079] In this embodiment of the invention, during the experiment, the power switch is turned on, and current is transmitted to the metal pipe section 10 and the corrosion test piece 6 through the sliding rheostat 2, thereby forming cathodic protection for the metal pipe section 10. The ammeter 4 and voltmeter 3 detect the real-time current and voltage values ​​transmitted to the metal pipe section 10 and the corrosion test piece 6. If the real-time current and voltage values ​​do not meet the preset current and voltage values, the position of the slider of the sliding rheostat 2 is adjusted to change the current and voltage values ​​transmitted to the metal pipe section 10 and the corrosion test piece 6 until the real-time current and voltage values ​​are equal to the preset current and voltage values, respectively.

[0080] Step 4: After the medium in the storage tank 11 enters the pipeline, the flow rate adjustment mechanism is activated to detect the real-time flow rate of the medium in the pipeline. If the real-time flow rate is not equal to the preset flow rate, the flow rate adjustment mechanism is used to adjust the real-time flow rate of the medium in the pipeline to make it equal to the preset flow rate.

[0081] In this embodiment of the invention, during the experiment, when the medium in the storage tank 11 enters the pipeline, the flow meter 13 detects the real-time flow rate of the medium in the pipeline. If the real-time flow rate is less than the preset flow rate required for the experiment, the circulation pump 12 is started to increase the flow rate of the medium in the pipeline. The impeller rotation speed of the circulation pump 12 is gradually increased, so that the flow rate of the medium in the pipeline can be gradually increased until the real-time flow rate of the medium is equal to the preset flow rate.

[0082] Step 5: After the predetermined time has elapsed, remove the corrosion test piece 6 to complete the simulated DC interference corrosion experiment.

[0083] In this embodiment of the invention, the predetermined time is the simulated interference corrosion time of the pipeline without cathodic protection. After the predetermined time has elapsed, 10 corrosion test pieces 6 are taken out from the two insulated pipe sections 7. By observing and combining various interference corrosion factors set in the laboratory, namely the content of oxidizing gas in the medium, medium temperature, medium flow rate, medium flow direction, interference corrosion voltage, interference corrosion current and distance from the interference source, the corrosion status of the corrosion test pieces 6 caused by the change of individual interference corrosion factors can be accurately evaluated.

[0084] In this embodiment of the invention, a controller is also included; the controller is connected to a gas regulating mechanism, a temperature regulating mechanism, a current and voltage regulating mechanism, and a flow rate regulating mechanism. Specifically, the controller is connected to a second valve on the oxidation inlet pipe 18, a third valve on the displacement inlet pipe 19, a fourth valve on the exhaust pipe 20, a gas concentration detector 21, a heating temperature controller 15, an adjustable resistor, an ammeter 4, a voltmeter 3, a constant current and voltage DC power supply 1, a circulating pump 12, a flow meter 13, and a temperature sensor 17. Preset concentration, preset temperature, preset voltage and current values, preset flow rate, and preset time are pre-set in the controller. The controller stores computer program instructions, which, when executed by the processor within the controller, enable the implementation of the aforementioned experimental method.

[0085] This invention utilizes a current and voltage adjustment mechanism to individually control the simulated interference voltage of 10 corrosion test pieces 6. The circulating pump 12 drives the medium to circulate in the pipeline, and the electric heating rod 16 and temperature controller control the medium temperature. This allows for the simulation of interference corrosion of the corrosion test pieces 6 in the flowing medium. It enables individual control of factors such as interference corrosion voltage, interference corrosion current, distance from the interference source, medium flow rate, relative flow direction of the medium and interference current, medium temperature, and content of oxidizing gases in the medium, ensuring the accuracy of the interference corrosion simulation test.

[0086] In this invention, the medium flow pipe is configured as a transversely open U-shape, and the circulating pump 12 drives the medium to achieve forward and reverse flow relative to the DC interference current. The pipe is divided into a metal part, namely the metal pipe section 10, and a non-metal part, namely the insulating pipe section 7. The corrosion test piece 6 is connected inside the non-metallic pipe section 10, forming an interfering corrosion environment with the metal pipe section 10. Multiple corrosion test pieces 6 are distributed at equal distances along the axis inside the insulating pipe section 7 to achieve individual control of the distance from the interference source.

[0087] Using the DC interference corrosion simulation device of this invention, test results can be obtained in as little as 4 days. The entire simulation process is intuitive, efficient, quantifiable, and allows for the monitoring and evaluation of individual interference corrosion factors. This invention can test the impact of a single factor on DC interference corrosion without changing other conditions. By simulating corrosion conditions in a real environment through DC interference corrosion tests, the degree of influence of different factors on interference corrosion can be understood, allowing for targeted protective measures to be proposed, improving the effectiveness of interference corrosion protection, and mitigating perforation failure of buried pipelines caused by DC interference corrosion.

[0088] The above embodiments are merely illustrative of implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A device for simulating DC interference corrosion, characterized in that, It comprises: a pipeline; an inlet and an outlet of the pipeline are connected with a liquid storage tank (11) respectively, and the liquid storage tank (11) is filled with a medium; the liquid storage tank (11) is connected with a gas adjusting mechanism for injecting an oxidizing gas into the medium, detecting and adjusting the concentration of the oxidizing gas in the medium; the liquid storage tank (11) is connected with a temperature adjusting mechanism for detecting and adjusting the temperature of the medium; the pipeline is provided with an insulated pipe section (7), and a plurality of corrosion coupons (6) are installed in the insulated pipe section (7) along the axial direction of the pipeline; the corrosion coupons (6) are connected with the positive pole of a power supply through a current-voltage adjusting mechanism, and the non-insulated pipe section of the pipeline is connected with the negative pole of the power supply through the current-voltage adjusting mechanism; the pipeline is provided with a flow rate adjusting mechanism for detecting and controlling the flow rate of the medium.

2. The apparatus according to claim 1, wherein The gas adjusting mechanism comprises an oxidizing gas inlet pipe (18), a displacement gas inlet pipe (19), a gas concentration detection unit and an exhaust pipe (20); one end of the oxidizing gas inlet pipe (18) is connected with an oxidizing gas source, and the other end is communicated with the liquid storage tank (11); one end of the displacement gas inlet pipe (19) is connected with a displacement gas source, and the other end is communicated with the liquid storage tank (11); the gas concentration detection unit is connected with the liquid storage tank (11) and is used for detecting the concentration of the oxidizing gas in the medium in the liquid storage tank (11); the exhaust pipe (20) is communicated with the liquid storage tank (11) and is located at the top of the liquid storage tank (11).

3. The simulated DC interference corrosion device according to claim 1, characterized in that, It further comprises: a pressure gauge (22); the pressure gauge (22) is fixed on the top of the liquid storage tank (11) and is communicated with the inside of the liquid storage tank (11) and is used for detecting the pressure in the liquid storage tank (11).

4. The simulated DC interference corrosion device according to claim 1, characterized in that, The temperature adjusting mechanism comprises a heating temperature controller (15), an electric heating rod (16) and a temperature sensor (17); the electric heating rod (16) is installed in the inside of the liquid storage tank (11), and the electric heating rod (16) is connected with the heating temperature controller (15) through a wire; the heating temperature controller (15) is connected with a power supply, and the heating temperature controller (15) is used for controlling the heating temperature of the electric heating rod (16); the temperature sensor (17) is connected with the liquid storage tank (11) and the heating temperature controller (15) respectively.

5. The simulated DC interference corrosion device according to claim 1, characterized in that, The current-voltage adjusting mechanism comprises an adjustable resistor, an ammeter (4) and a voltmeter (3); the adjustable resistor is connected with a power supply, and the non-insulated pipe section of the pipeline is connected with the negative pole of the power supply through a wire; the sliding end of the adjustable resistor is connected with the corrosion coupons (6) through the ammeter (4); one end of the voltmeter (3) is connected with the wire between the adjustable resistor and the negative pole of the power supply, and the other end is connected with the wire between the adjustable resistor and the ammeter (4).

6. The simulated DC interference corrosion device according to claim 1, characterized in that, The flow rate adjusting mechanism comprises a circulating pump (12) and a flow meter (13); the circulating pump (12) is installed on the pipeline and is used for controlling the flow rate of the medium in the pipeline; the flow meter (13) is installed in the inside of the pipeline and is used for detecting the flow rate of the medium in the pipeline.

7. The device according to any one of claims 1-6, characterized in that: The pipeline is U-shaped, and the ends of the two arms of the U-shaped pipeline are open and respectively communicate with the liquid storage tank (11); The two arms of the U-shaped pipeline respectively have the insulating pipe section (7).

8. The method of claim 1, wherein the method is a method of simulating the DC interference corrosion of the device, and wherein the method comprises: The method comprises the steps of: ​ controlling the gas adjusting mechanism to inject oxidizing gas into the medium in the liquid storage tank, detecting the real-time concentration of the oxidizing gas in the medium, and determining whether the real-time concentration is equal to the preset concentration; if not, adjusting the real-time concentration of the oxidizing gas in the medium through the gas adjusting mechanism so as to make it equal to the preset concentration; controlling the temperature adjusting mechanism to detect the real-time temperature of the medium in the liquid storage tank, determining whether the real-time temperature is equal to the preset temperature, and adjusting the real-time temperature of the medium through the temperature adjusting mechanism so as to make it equal to the preset temperature; controlling the power supply to make the current transmitted to the pipeline and the corrosion test piece through the current and voltage adjusting mechanism, detecting the real-time current and voltage value of the pipeline and the corrosion test piece, determining whether the real-time current and voltage value is equal to the preset current and voltage value, and adjusting the real-time current and voltage value through the current and voltage adjusting mechanism so as to make it equal to the preset current and voltage value; controlling the flow rate adjusting mechanism to detect the real-time flow rate of the medium in the pipeline after the medium in the liquid storage tank enters the pipeline, determining whether the real-time flow rate is equal to the preset flow rate, and adjusting the real-time flow rate of the medium in the pipeline through the flow rate adjusting mechanism so as to make it equal to the preset flow rate; after a predetermined time, taking out the corrosion test piece, and completing the simulation of the direct current interference corrosion experiment.

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