System and method for relieving alternating current and direct current stray current interference of buried metal pipeline

Abstract

The invention discloses a system and method for relieving alternating current and direct current stray current interference of a buried metal pipeline, and relates to the technical field of metal pipeline current corrosion and protection, and the system is composed of a reference electrode (CSE), a test piece (Coupon), a switch K1, a switch K2, a pipeline (Pipe), a capacitor (c), a diode (D), a variable resistor (R), a power supply (PW) and a grounding electrode (G). The alternating stray current flows to the ground from the capacitor, so that the influence of the interference of the alternating stray current on the pipeline is reduced; the direct-current stray electricity flows to the ground through the diode, a part of the current flowing to the ground flows to the pipeline from the defect position of the anti-corrosion layer of the pipeline through soil, the part of the current can exert cathode protection on the pipeline, and then the effect of inhibiting corrosion of the pipeline is achieved. The cathode protection potential is in a reasonable range, and the corrosion inhibition effect on the pipeline is better achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of current corrosion and protection of metal pipelines, and specifically to a system and method for alleviating the interference of alternating and direct current stray currents on buried metal pipelines. Background Art

[0002] The interference of alternating and direct current stray currents on buried metal pipelines refers to the interference of stray currents generated by direct current electrified railway systems, direct current welding machines and other power transmission systems or certain industrial electrical equipment and external cathodic protection systems near the buried metal pipelines on the pipelines. These stray currents may be applied to the metal pipelines through capacitive coupling, inductive coupling and resistive coupling, causing hazards such as corrosion to the pipelines; the stray currents flow into and out of the pipelines, resulting in accelerated electrochemical corrosion at the outflow positions of the metal pipelines, and stray current corrosion usually occurs at local positions with small resistance and easy discharge, such as defective parts where the coating is damaged or peeled off, and sharp corner edges. Therefore, stray currents may cause pipeline corrosion perforation and lead to safety accidents such as leakage. For this reason, the present application proposes a system and method for alleviating the interference of alternating and direct current stray currents on buried metal pipelines to solve the above problems. Summary of the Invention

[0003] (1) Technical Problems to be Solved

[0004] In view of the deficiencies of the prior art, the present invention provides a system and method for alleviating the interference of alternating and direct current stray currents on buried metal pipelines, and solves the technical problems raised in the above background.

[0005] (2) Technical Solutions

[0006] To achieve the above object, the technical solution adopted by the present invention is: a system for alleviating the interference of alternating and direct current stray currents on buried metal pipelines, which is composed of a reference electrode (CSE), a coupon, a switch K1, a switch K2, a pipeline (Pipe), a capacitor (c), a diode (D), a variable resistor (R), a power supply (PW) and a grounding electrode (G);

[0007] A power supply (PW) is added between the pipeline (Pipe) and the grounding electrode (G) to generate a voltage between the pipeline (Pipe) and the grounding electrode (G) for discharging the stray current on the pipeline (Pipe) and protecting the pipeline from corrosion;

[0008] A circuit one is provided between the pipeline (Pipe) and the grounding electrode (G), and a capacitor (c) is provided on the circuit one between the pipeline (Pipe) and the grounding electrode (G) for the alternating current flowing out of the pipeline (Pipe) to flow into the ground through the capacitor (c) and the grounding electrode (G);

[0009] A circuit two is provided between the pipe and the ground electrode (G), and a switch K1, a variable resistor (R), and a diode (D) are provided on the circuit two between the pipe and the ground electrode (G) for the DC current flowing out of the pipe to flow into the earth through the diode (D) and the ground electrode (G).

[0010] Preferably, the coupon is connected in parallel with the pipe, and the coupon is used to simulate and replace the pipeline. A switch K2 is provided between the coupon and the pipe. By opening the switch K2, the coupon can be incorporated into the circuit, and the reference electrode (CSE) is connected in parallel with the coupon.

[0011] Preferably, a voltmeter (V) is installed between the reference electrode (CSE) and the coupon to calibrate the basic potential of the coupon.

[0012] Preferably, the circuit one and the circuit two are connected in parallel.

[0013] A method for using a system for mitigating AC and DC stray current interference in buried metal pipelines, the method comprising the following steps:

[0014] S1: The AC current flowing out of the pipe flows into the earth through the capacitor (c) and the ground electrode (G) to reduce the influence of AC stray current interference on the pipe. The DC current flowing out of the pipe flows into the earth through the switch K2, the variable resistor (R), the diode (D), and the ground electrode (G);

[0015] S2: In the step of the DC current flowing into the earth, the magnitude of the off-shore current flowing into the earth can be adjusted by adjusting the state of the switch K1, the output value of the power supply PW, and the resistance value of the adjustable resistor R, so as to adjust the drainage protection effect;

[0016] S3: Adjust the drainage protection and measure the off-potential of the coupon using the instantaneous power-off method to simulate the pipe protection potential;

[0017] S4: Determine whether the instantaneous off-potential of the coupon meets the requirements;

[0018] S5: Measure the instantaneous off-potential of the coupon. When the instantaneous off-potential of the coupon gradually shifts towards the required protection potential and reaches the requirement, close the switch K1 and turn on the power supply PW;

[0019] S6: Repeat step S4 to keep the cathodic protection potential of the pipe within a reasonable range.

[0020] Preferably, when determining whether the instantaneous off-potential of the coupon meets the requirements in step S4, the following steps are included:

[0021] Step 1: If the instantaneous power-off potential of the test piece meets the requirements, switches K1, power supply PW, and resistor R remain in their current states;

[0022] Step 2: If the instantaneous power-off potential of the test piece does not meet the requirements, first adjust the output value of the power supply PW and the resistance value of the resistor R to make the instantaneous power-off potential of the test piece reach the requirements as much as possible;

[0023] Step 3: If the resistance and the power supply output value are adjusted to the extreme values and the instantaneous power-off potential of the test piece still cannot meet the requirements, then disconnect switch K1 and turn off power supply PW.

[0024] (III) Beneficial effects

[0025] The beneficial effects of the present invention are as follows:

[0026] For the system and method for alleviating AC and DC stray current interference of buried metal pipelines, by allowing the AC stray current to flow from the capacitor to the ground, the influence of the AC stray current interference on the pipeline is reduced; the DC stray current flows to the ground through the diode, and a part of the current flowing to the ground will flow from the defect of the pipeline anticorrosion layer to the pipeline through the soil, and this part of the current will apply cathodic protection to the pipeline, thereby playing a role in inhibiting pipeline corrosion. Moreover, the system adjusts the state of switch K1, the output value of power supply PW, and the resistance value of the adjustable resistor R to make the cathodic protection potential within a reasonable range, better playing a role in inhibiting corrosion of the pipeline. Description of the drawings

[0027] Figure 1 is a schematic diagram of the system composition of the present invention;

[0028] Figure 2 is a schematic diagram of the working process of the present invention. Detailed implementation manners

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] As Figure 1-2 shown, the present invention provides a technical solution: a system for alleviating AC and DC stray current interference of buried metal pipelines, which is composed of a reference electrode (CSE), a test piece (Coupon), switches K1, K2, a pipeline (Pipe), a capacitor (c), a diode (D), a variable resistor (R), a power supply (PW), and a grounding electrode (G);

[0031] A power supply (PW) is attached between the pipe and the grounding electrode (G) to generate a voltage between the pipe and the grounding electrode (G) for discharging the stray current on the pipe and protecting the pipe from corrosion.

[0032] A circuit one is provided between the pipe and the ground electrode (G), and a capacitor (c) is provided on the circuit one between the pipe and the ground electrode (G) for the alternating current flowing out of the pipe to flow into the earth through the capacitor (c) and the grounding electrode (G).

[0033] A circuit two is provided between the pipe and the ground electrode (G), and a switch K1, a variable resistor (R) and a diode (D) are provided on the circuit two between the pipe and the ground electrode (G) for the direct current flowing out of the pipe to flow into the earth through the diode (D) and the grounding electrode (G), and the circuit one and the circuit two are in parallel.

[0034] The coupon is in parallel with the pipe, and the coupon is used to simulate and replace the pipeline, and a switch K2 is provided between the coupon and the pipe. The coupon can be incorporated into the circuit by turning on the switch K2, and the reference electrode (CSE) is in parallel with the coupon, and a voltmeter (V) is installed between the reference electrode (CSE) and the coupon to calibrate the basic potential of the coupon.

[0035] A method for using a system for alleviating the interference of alternating and direct current stray currents on buried metal pipes, characterized in that: the method includes the following steps:

[0036] S1: The alternating current flowing out of the pipe flows into the earth through the capacitor (c) and the grounding electrode (G) to reduce the influence of the alternating current stray current interference on the pipe, and the direct current flowing out of the pipe flows into the earth through the switch K2, the variable resistor (R), the diode (D) and the grounding electrode (G).

[0037] S2: In the step of the direct current flowing into the earth, the magnitude of the off-shore current flowing into the earth can be adjusted by adjusting the state of the switch K1, the output value of the power supply PW and the resistance value of the adjustable resistor R, so as to adjust the drainage protection effect.

[0038] S3: The instant power-off method is used to measure the off-state potential of the coupon to simulate the pipeline protection potential when adjusting the drainage protection.

[0039] S4: Judge whether the instant power-off potential of the coupon meets the requirements.

[0040] When judging whether the instant power-off potential of the coupon meets the requirements, the following steps are included:

[0041] Step 1: If the instantaneous power-off potential of the test piece meets the requirements, switch K1, power supply PW, and resistor R remain in their current states;

[0042] Step 2: If the instantaneous power-off potential of the test piece does not meet the requirements, first adjust the output value of the power supply PW and the resistance value of the resistor R to make the instantaneous power-off potential of the test piece reach the requirements as much as possible;

[0043] Step 3: If the resistance and the power supply output value are adjusted to the extreme values and the instantaneous power-off potential of the test piece still cannot meet the requirements, then disconnect switch K1 and turn off power supply PW;

[0044] S5: Measure the instantaneous power-off potential of the test piece. When the instantaneous power-off potential of the test piece gradually shifts towards the required protection potential and reaches the requirements, close switch K1 and turn on power supply PW;

[0045] S6: Repeat step S4 to keep the cathodic protection potential of the pipeline within a reasonable range

[0046] In the description of the present invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0047] In the present invention, unless otherwise clearly specified and limited, for example, it can be fixedly connected, detachably connected, or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. Unless otherwise clearly limited, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0048] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for alleviating AC and DC stray current interference in buried metal pipelines, characterized by: The system consists of a reference electrode (CSE), a coupon (Coupon), a switch K1, a switch K2, a pipe (Pipe), a capacitor (c), a diode (D), a variable resistor (R), a power supply (PW) and a grounding electrode (G); A power source (PW) is attached between the pipeline (Pipe) and the grounding electrode (G) so that a voltage is generated between the pipeline (Pipe) and the grounding electrode (G) to discharge the stray current on the pipeline (Pipe); A circuit 1 is provided between the pipe (Pipe) and the ground electrode (G), and a capacitor (c) is provided on the circuit 1 between the pipe (Pipe) and the ground electrode (G); A circuit 2 is provided between the pipeline (Pipe) and the ground electrode (G), and a switch K1, a variable resistor (R) and a diode (D) are provided on the circuit 2 between the pipeline (Pipe) and the ground electrode (G), so as to allow the direct current flowing out of the pipeline (Pipe) to flow into the earth through the diode (D) and the ground electrode (G).

2. A system for alleviating AC and DC stray current interference in buried metal pipelines according to claim 1, characterized in that: The coupon is connected in parallel with the pipe, and the coupon is used to simulate the pipe. A switch K2 is provided between the coupon and the pipe. When the switch K2 is turned on, the coupon can be incorporated into the circuit, and the reference electrode (CSE) and the coupon are connected in parallel.

3. A system for alleviating AC and DC stray current interference in buried metal pipelines according to claim 2, characterized in that: A voltmeter (V) is installed between the reference electrode (CSE) and the coupon to calibrate the basic potential of the coupon.

4. A system for alleviating AC and DC stray current interference in buried metal pipelines according to claim 1, characterized in that: The circuit one and the circuit two are connected in parallel.

5. The method for using the system for alleviating AC and DC stray current interference in buried metal pipelines according to claim 1, characterized in that: The method comprises the following steps: S1: The AC current flowing out of the pipeline flows into the earth through the capacitor (c) and the grounding electrode (G), reducing the impact of AC stray current interference on the pipeline. The DC current flowing out of the pipeline flows into the earth through the switch K2, the variable resistor (R), the diode (D) and the grounding electrode (G); S2: In the step of direct current entering the earth, the size of the offshore current flowing to the earth can be adjusted by adjusting the state of the switch K1, the output value of the power supply PW and the resistance value of the adjustable resistor R, thereby adjusting the drainage protection effect; S3: Adjust the drainage protection and use the instantaneous power-off method to measure the power-off potential of the test piece to simulate the pipeline protection potential; S4: Determine whether the instantaneous power-off potential of the test piece meets the requirements; S5: Measure the instantaneous power-off potential of the test piece. When the instantaneous power-off potential of the test piece gradually shifts toward the required protection potential and reaches the requirement, close the switch K1 and turn on the power supply PW; S6: Repeat step S4 to keep the pipeline cathodic protection potential within a reasonable range.

6. The method for using the system for alleviating AC and DC stray current interference in buried metal pipelines according to claim 1, characterized in that: In step S4, when judging whether the instantaneous power-off potential of the test piece meets the requirement, the following steps are included: Step 1: If the instantaneous power-off potential of the test piece meets the requirements, the switch K1, power supply PW and resistor R remain in the current state; Step 2: If the instantaneous power-off potential of the test piece does not meet the requirements, first adjust the output value of the power supply PW and the resistance value of the resistor R to try to make the instantaneous power-off potential of the test piece meet the requirements; Step 3: If the resistance and power output values ​​are adjusted to extreme values ​​and the instantaneous power-off potential of the test piece still cannot meet the requirements, disconnect the switch K1 and turn off the power supply PW.

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