Fuel gas pipeline stray current eliminating device with external deep well type anode

Abstract

The invention relates to a fuel gas pipeline stray current eliminating device with external deep well type anodes. The fuel gas pipeline stray current eliminating device comprises a cathode protection system arranged at a fuel gas gate station and the deep well type anodes buried at the set distance of a local fuel gas pipe section. The deep well type anode comprises an inactive section and an active section which are sequentially arranged from top to bottom, the active section comprises a plurality of high-silicon cast iron anodes, and the high-silicon cast iron anodes are connected to a current drainage device on the ground through independent cables to achieve forced grounding current drainage. Compared with the prior art, the subway stray current around the gas pipeline can be better eliminated, and the corrosion risk of the gas pipeline is reduced.

Description

Technical Field

[0001] The present invention relates to the field of gas pipeline laying, in particular to a deep-well anode bed for eliminating stray current in gas pipelines. Background Art

[0002] With the rapid development of technology and urbanization, rail transit is playing an increasingly important role in cities. Since subway power systems generally use DC traction systems, stray currents are generated after subway operation. Long-term exposure to stray currents can cause severe electrochemical corrosion in buried metal gas pipelines, posing a significant safety hazard. Reducing the interference of subway stray currents around metal gas pipelines has become an urgent issue.

[0003] Currently, there is a plan to install a cathodic protection system at the gas gate station for drainage. However, the subway tracks, maintenance bases (garages), and mainline tracks near the cathodic protection system will interfere with the protection current of the anode bed, making it impossible to achieve the expected protection effect for pipelines far away from the drainage point. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a gas pipeline stray current elimination device with an external deep well anode, which can better eliminate the subway stray current around the gas metal pipeline and reduce the risk of gas pipeline corrosion.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A gas pipeline stray current elimination device with an external deep-well anode includes a cathodic protection system arranged at a gas gate station and a deep-well anode buried at a set distance in a local gas pipeline section;

[0007] The deep well anode includes an inactive section and an active section arranged in sequence from top to bottom. The active section includes multiple high-silicon cast iron anodes, and the multiple high-silicon cast iron anodes are connected to a drainer on the ground through independent cables to achieve forced grounding and drainage.

[0008] Preferably, the active section comprises a plurality of longitudinally arranged high-silicon cast iron anodes of the same specifications.

[0009] Preferably, each of the high silicon cast iron anodes comprises a plurality of high silicon cast iron anode substructures connected by side-by-side welding, and each high silicon cast iron anode substructure has the same specifications.

[0010] Preferably, the plurality of high-silicon cast iron anodes are evenly distributed in the longitudinal direction of the active section.

[0011] Preferably, the ratio of the length of the inactive segment to the length of the active segment is 1:2.

[0012] Preferably, the inactive section is a coarse sand and gravel inactive section.

[0013] Preferably, the distance between the buried point of the deep-well anode and the gas pipeline is 10 to 15 meters.

[0014] Preferably, the inactive section of the cable close to the ground is also covered with a cable protection tube.

[0015] Preferably, the gas pipeline is connected to the gas gate station through an insulating joint, and the cathodic protection system includes a micro-controlled constant potentiostat, which outputs a constant current to act on the gas pipeline, and the constant current is 3 to 4A.

[0016] Preferably, the deep-well anode further comprises an exhaust pipe provided through the inactive section and the active section.

[0017] Preferably, the inactive section of the cable close to the ground is also covered with a cable protection tube.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention, on the basis of laying out a cathodic protection system at a gas gate station, additionally buries deep-well anodes near a gas pipeline that is far from a discharge point. The forced discharge of the local deep-well anodes can significantly reduce the interference of stray currents, effectively improve the cathodic protection effect, and enhance the overall stray current discharge effect.

[0020] (2) The deep-well anode of the present invention adopts multiple high-silicon cast iron anodes through the active section, which has a greater drainage intensity and greatly improves the stray current effect. In addition, each high-silicon cast iron anode adopts multiple high-silicon cast iron anode substructures connected by side-by-side welding, which has higher structural stability. The modular combination setting further reduces the subsequent replacement and maintenance costs.

[0021] (3) The active section of the deep-well anode in the present invention accounts for 2 / 3, ensuring that the anode has sufficient surface area to participate in the electrochemical reaction, making the current output more uniform, the protection efficiency high, and avoiding local polarization or overheating.

[0022] (4) The exhaust pipe of the present invention is set up throughout the inactive section and the active section, which can discharge the excess gas generated by the reaction in time, avoiding the uneven current density distribution in the local area of the anode caused by the gas, which accelerates the corrosion rate of some areas and improves the service life of the deep well anode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the layout of the stray current elimination device for the gas pipeline with the internal and external deepened well anode in the embodiment;

[0024] Figure 2This is a schematic diagram of the deep well anode structure;

[0025] Figure 3 The on-off potential of the test pile in the embodiment; wherein (a) and (b) are the on-off potentials of the test pile in different time periods respectively;

[0026] Figure 4 : The power-off potential changes before and after applying the external current in the embodiment; wherein (a) and (b) correspond to the period of subway stray current interference and the period without subway stray current interference, respectively;

[0027] Figure 5 The change of the on-state potential after the deep-well anode is drained in the embodiment; wherein (a) and (b) correspond to the on-state potential and the positive and negative root mean square of the on-state potential, respectively;

[0028] Figure 6 : The power-off potential background value and power-off potential of the test pile in the embodiment after deep-well anode grounding and drainage; wherein (a) is the power-off potential background value, and (b) is the power-off potential;

[0029] Figure 7 The power-off potential changes in the same period of time on different days before and after deep well anode drainage in the embodiment; (a) and (b) correspond to the period of subway stray current interference and the period without stray current interference, respectively;

[0030] Figure 8 The changes in the power-off potential background value of each test pile in the deep-well anode interference range test; (a), (b), and (c) correspond to the 4#, 8#, and 9# test piles, respectively;

[0031] Figure 9 Figure 3. Changes in the characteristic parameters of the power-off potential fluctuations of deep-well anodes before and after forced drainage in the deep-well anode interference range test. (a), (b), and (c) correspond to the 4#, 8#, and 9# test piles, respectively.

[0032] Reference numerals:

[0033] A-Subway Station A; B-Subway Station B; C-Intersection of the mainline track and the access track; D-Gas garage; E-Gas gate station; F-Subway line; G-Deep well anode; H-Gas pipeline;

[0034] 1- inactive section; 2- active section, 21- high silicon cast iron anode; 3- cable, 31- cable protection tube; 4- drainer; 5- exhaust pipe. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0036] Example

[0037] like Figure 1 As shown in Figure 1, a high-pressure gas pipeline H in a certain city runs from north to south through a subway branch track and subway line F, and then reaches a gas gate station E. Gas pipeline H is subject to severe interference from stray currents from the adjacent subway.

[0038] When an impressed current is applied at gas gate station E to protect the pipeline section of test pile 6, the protective current is released through the anode groundbed and must cross the subway running tracks and the mainline track of the garage to reach the pipeline section of test pile 6. At this time, the leakage current field from the running tracks interferes with the impressed current field, preventing the anode groundbed current at the gate station from smoothly reaching the pipeline section of test pile 6. In this embodiment, gas pipeline H is equipped with an insulating joint before entering gas gate station E and is protected by a cathodic protection system. The anode groundbed within gas gate station E is approximately 1000m away from test pile 6.

[0039] To address the above issues, this embodiment provides a gas pipeline stray current elimination device with an external deep-well anode, comprising a cathodic protection system deployed at a gas gate station E, and a deep-well anode G buried at a set distance in a local gas pipeline section;

[0040] The deep well anode G includes an inactive section 1 and an active section 2 arranged in sequence from top to bottom. The active section 2 includes multiple high silicon cast iron anodes 21. The multiple high silicon cast iron anodes 21 are connected to the drainer 4 on the ground through independent cables to achieve forced grounding and drainage.

[0041] The active section 2 comprises multiple longitudinally arranged high-silicon cast iron anodes 21 of identical specifications. Each high-silicon cast iron anode 21 comprises multiple high-silicon cast iron anode substructures connected by parallel welding, each with identical specifications. The multiple high-silicon cast iron anodes are evenly spaced longitudinally along the active section. The ratio of the length of the inactive section to the length of the active section is 1:2. Inactive section 1 is a coarse sand and gravel inactive section. The deep-well anode is buried 10 to 15 meters from the gas pipeline. Gas pipeline E is connected to the gas gate station via an insulated joint. The cathodic protection system includes a micro-controlled potentiostat that outputs a constant current of 3 to 4A to the gas pipeline. The deep-well anode also includes an exhaust pipe 5 that runs through the inactive and active sections. The cable 3 in the inactive section, which is close to the ground, is also covered with a cable protection tube 31.

[0042] Next, the effectiveness of the gas pipeline stray current elimination device with an external deep well anode designed in this embodiment was verified.

[0043] 1. Only introduce cathodic protection system

[0044] According to the cathodic protection parameter measurement method for buried steel pipelines specified in GB / T 21246, a long-lasting copper / saturated copper sulfate reference electrode (CSE) and a test piece made of the same material as the pipeline were used to measure the on-state potential of the pipeline section. A relay was used to perform a continuous cycle of 12 seconds on and 3 seconds off to collect the off-state potential of the test piece.

[0045] like Figure 3 As shown, during subway operation, the on- and off-current potentials of the 6# test pile pipeline section exhibited periodic and dramatic fluctuations. During the day, the on-current potential fluctuated between -4.409 and 2.465 V, and the off-current potential fluctuated between -1.074 and -0.357 V. At night, during subway outages, the on-current potential remained stable at -1.045 V, and the off-current potential remained stable at -0.765 V, failing to meet the -850 mV cathodic protection criterion. Gas pipeline H was severely affected by the subway's dynamic DC stray currents, necessitating additional protective measures. Clearly, even with impressed current protection, the pipeline at this location still experienced significant interference from subway operation.

[0046] 2. Gate station plus constant current output

[0047] The cathodic protection system of the gate station is as follows: Figure 1 As shown, by closing the gate station cathodic protection system (constant potentiostat) and setting the gate station cathodic protection system to a constant output of 3A, the drainage effect on the 6# test pile pipeline section before and after applying the impressed current is analyzed.

[0048] The power-off potential of the 6# test pile before and after applying the external current is as follows: Figure 4 As shown in the figure, after the impressed current output is 3A, the natural potential drops from -0.625V to -0.8V during the subway's undisturbed period, and the average power-off potential drops from -0.55V to -0.753V during the subway's operation period, indicating that the impressed current cathodic protection effect is quite obvious. However, because the average power-off potential level still does not meet the cathodic protection criterion of -0.85V, it indicates that due to interference from the nearby subway tracks and mainline tracks, the protection current output by the cathodic protection system at the gate station cannot fully reach the pipeline at test pile 6, and the expected protection effect cannot be achieved.

[0049] The gas pipeline section at test pile 6 is located near the garage's access tracks. One-way conduction devices are installed between the garage (point D) and the access tracks, and between the mainline tracks and the access tracks at their intersection (point C). This ensures current flows from the garage to the mainline tracks, ensuring the safety of garage maintenance personnel. When the subway accelerates out of Station A, the train draws current from the catenary, while the leakage current returns to the garage grounding electrode (point D). The potential at point C drops, forming a current loop from D to C to A to D.

[0050] 3. Deep well anode forced grounding and drainage

[0051] In this example, a deep-well anode was buried 15 meters from the gas pipeline, at a depth of 38 meters. The active section was 24 meters long, and the output current was set to 4 A. By monitoring the power-off potential changes of the deep-well anode before and after forced drainage, the interference mitigation effect on the protected pipeline and adjacent pipe sections was analyzed.

[0052] like Figure 5 As shown in the figure, after the 6# test pile is drained by deep well anode grounding, the energized potential A Max5％ From 1V before discharge to 0V level, and A Min5％ The positive and negative RMS values of the on-state potential are significantly reduced, and the interference fluctuation amplitude is significantly reduced, indicating that the deep-well anode grounding drainage can effectively mitigate the interference of stray current.

[0053] like Figure 6 , after the deep well anode grounding and drainage of the 6# test pile, the power-off potential background value decreased, and the negative offset of the power-off potential background value was about 0.1V, but it still did not reach the cathodic protection level of -0.85V. Through on-site test piece excavation, it was found that the position of the test piece changed when the deep well was set (2023-12-22 to 2024-01-19), and the test piece was no longer close to the reference electrode to eliminate IR drop. For this reason, after the test piece position calibration on January 20, 2024, the power-off potential shifted negatively, and it was able to meet the -0.85V cathodic protection criterion in continuous monitoring for many days; the power-off potential Avg max5％ After discharge, it decreases slightly, while Avg min5％ There is a significant decrease, indicating that the deep well anode grounding drainage can promote the negative shift of the power-off potential and improve the cathodic protection level of the pipeline.

[0054] The changes of power-off potential at the same time on different days before and after forced discharge of deep well anode are as follows: Figure 7 As shown in the figure, the off-power potential of the pipeline is obviously negative; during the subway outage period, the average off-power potential at night drops from -0.732V to -0.978V, and during the daytime subway operation period, the average off-power potential level drops from -0.718V to -0.989V, both meeting the -0.85V cathodic protection standard, and the drainage effect is obvious.

[0055] 4. Deep well anode interference range assessment

[0056] Since different cathodic protection measures will cause mutual interference, in order to evaluate the impact of deep-well anode drainage near the 6# test pile on the potential interference of the adjacent pipeline, the 4#, 8#, and 9# test piles adjacent to the pipeline were selected. The power-off potential background value during the non-interference period and the power-off potential fluctuation mean and standard deviation during the subway operation interference period were used as evaluation index parameters to analyze the parameter changes before and after deep-well anode drainage.

[0057] like Figure 8 As shown in the figure, after the deep well anode drainage, the power-off potential background values of the 4, 8, and 9# test piles showed a negative shift trend; the fluctuation characteristic parameters of the power-off potential during the subway operation interference period are as follows: Figure 9 As shown in the figure, the mean levels of the off-power potentials of the pipeline sections at the 4#, 8# and 9# test piles also shifted negatively to a certain extent, indicating that the forced drainage of the deep-well anode at the 6# test pile did not interfere with the cathodic protection system of the adjacent pipelines, that is, the protection of the pipeline at the 6# test pile by the deep-well anode did not cause anodic interference to the adjacent pipelines.

[0058] In summary, subway tracks, maintenance bases (garages), and mainline tracks near cathodic protection stations can interfere with the protective current of the anode bed, preventing pipelines farther from the drainage point from achieving the desired protection effect. Localized deep-well anode forced drainage can significantly mitigate the interference of stray currents, effectively shifting the power-off potential to a negative level and improving cathodic protection effectiveness.

[0059] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A gas pipeline stray current elimination device with an external deep well anode, characterized in that: It includes a cathodic protection system deployed at the gas gate station and a deep well anode buried at a set distance in the local gas pipeline section; The deep well anode includes an inactive section and an active section arranged in sequence from top to bottom. The active section includes multiple high-silicon cast iron anodes, and the multiple high-silicon cast iron anodes are connected to a drainer on the ground through independent cables to achieve forced grounding and drainage.

2. A gas pipeline stray current elimination device according to claim 1, characterized in that: The active section comprises a plurality of longitudinally arranged high-silicon cast iron anodes of the same specifications.

3. A gas pipeline stray current elimination device according to claim 2, characterized in that: Each of the high-silicon cast iron anodes comprises a plurality of high-silicon cast iron anode substructures connected by side-by-side welding, and each of the high-silicon cast iron anode substructures has the same specifications.

4. A gas pipeline stray current elimination device according to claim 2, characterized in that: Multiple high-silicon cast iron anodes are evenly distributed in the longitudinal direction of the active section.

5. A gas pipeline stray current elimination device according to claim 1, characterized in that: The ratio of the length of the inactive segment to the length of the active segment is 1:

2.

6. A gas pipeline stray current elimination device according to claim 1, characterized in that: The inactive section is a coarse sand and gravel inactive section.

7. A gas pipeline stray current elimination device according to claim 1, characterized in that: The distance between the buried point of the deep well anode and the gas pipeline is 10 to 15 meters.

8. A gas pipeline stray current elimination device according to claim 1, characterized in that: The gas pipeline is connected to the gas gate station through an insulating joint. The cathodic protection system includes a micro-controlled constant potentiostat. The micro-controlled constant potentiostat outputs a constant current to act on the gas pipeline. The constant current is 3 to 4A.

9. A gas pipeline stray current elimination device according to claim 1, characterized in that: The deep well anode further comprises an exhaust pipe which is arranged through the inactive section and the active section.

10. A gas pipeline stray current elimination device according to claim 1, characterized in that: The inactive section of the cable close to the ground is also covered with a cable protection tube.

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