Fuel gas pipeline stray current eliminating device

Abstract

The utility model relates to a stray current eliminating device for a gas pipeline. The stray current eliminating device comprises a cathode protection system arranged at a gas gate station and a sacrificial anode buried at a set distance of a gas pipeline section, wherein a diode is connected in series between the sacrificial anode and the gas pipeline to serve as a polar electric drainage device, and only one-way circulation of current from the gas pipeline to the sacrificial anode to the soil is allowed. 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] This utility model relates to the field of gas pipeline laying, and in particular to a device for eliminating stray current in gas pipelines. Background Technology

[0002] With the rapid development of technology and urbanization, rail transit is playing an increasingly important role in cities. Because subway power systems generally use DC-powered traction systems, stray currents are generated after the subway begins operation. Long-term stray currents can cause severe electrochemical corrosion of buried gas pipelines, posing a significant safety hazard. Therefore, reducing stray current interference from subways around gas pipelines has become an urgent problem to be solved.

[0003] Currently, a solution is 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 can interfere with the protective current of the anode ground bed, causing pipelines that are far from the drainage point to fail to achieve the expected protection effect. Summary of the Invention

[0004] The purpose of this invention is to provide a stray current elimination device for gas pipelines with an external deep well anode, which can better eliminate stray currents around gas metal pipelines and reduce the risk of gas pipeline corrosion.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] A stray current elimination device for gas pipelines includes a cathodic protection system installed at a gas gate station and a sacrificial anode buried at a set distance in a gas pipeline section.

[0007] A diode is connected in series between the sacrificial anode and the gas pipeline as a polarity drain, allowing only unidirectional current flow from the gas pipeline to the sacrificial anode to the soil.

[0008] Preferably, a plurality of diodes are connected in series between the sacrificial anode and the gas pipeline.

[0009] Preferably, each series branch is equipped with an on / off switch.

[0010] Preferably, the cathodic protection system includes an anode ground bed installed at the gas gate station and a micro-controlled potentiostat, wherein the micro-controlled potentiostat outputs a constant current to the gas pipeline through the anode ground bed.

[0011] Preferably, the constant current is 3 to 4 A.

[0012] Preferably, the gas pipeline is connected to the gas gate station via an insulating joint.

[0013] Preferably, the device is equipped with multiple sacrificial anodes, which are arranged according to the relative positions of the gas pipeline and the subway line.

[0014] Preferably, the sacrificial anode is a zinc anode.

[0015] Preferably, the outer surface of the gas pipeline is provided with an external anti-corrosion layer.

[0016] Preferably, the outer anti-corrosion layer is a 3-layer PE outer anti-corrosion layer.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) Based on the cathodic protection system installed at the gas gate station, this utility model additionally buries a deep well anode near the gas pipeline that is far from the discharge point. By connecting a diode in series as a polarity drain, only the current is allowed to flow unidirectionally from the gas pipeline to the sacrificial anode to the soil. The forced discharge of the local deep well anode can significantly reduce the interference of stray current, effectively improve the cathodic protection effect, and enhance the overall stray current discharge effect.

[0019] (2) The redundant setting of multiple diodes connected in series between the sacrificial anode and the gas pipeline, and the on-off control by the on-off switch, can prevent the reverse current caused by the failure of the one-way control between the gas pipeline-sacrificial anode-soil after a single diode breaks down by turning off the branch where the broken diode is located in time, thus affecting the stray current elimination effect and making the reliability higher. Attached Figure Description

[0020] Figure 1 This is a schematic diagram showing the location of the stray current elimination device for the gas pipeline in the embodiment;

[0021] Figure 2 A schematic diagram of a structure in which a diode is connected in series between the sacrificial anode and the gas pipeline as a polarity drain;

[0022] Figure 3 The change in energized potential before and after the sacrificial anode drains; where (a) and (b) correspond to the energized potential and the de-energized potential, respectively;

[0023] Figure 4 The change in characteristic parameters of potential fluctuation before and after the sacrificial anode discharge is shown; where (a) and (b) correspond to the on-state potential and the off-state potential, respectively.

[0024] Figure 5 The potential change of the sacrificial anode in the test pile before and after the addition of a diode is shown in the example; where (a) and (b) correspond to the energized potential and the de-energized potential, respectively;

[0025] Figure 6The potential fluctuation characteristics of the sacrificial anode in the test pile before and after the addition of a diode are shown in the example; where (a) and (b) correspond to the on-state potential and the off-state potential, respectively.

[0026] Figure 7 The example illustrates the change in sacrificial anode current before and after polarity drainage.

[0027] Figure 8 The examples show the changes in sacrificial anode current and energizing potential; where (a) and (b) correspond to a polarized drain and a non-polarized drain, respectively.

[0028] Attached labels: A - Metro Station A; B - Metro Station B; C - Intersection of mainline track and depot access track; D - Garage; E - Gas gate station; F - Metro line; G - Deep well anode; H - Gas pipeline; 1 - Diode; 2 - Sacrificial anode. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. This embodiment is based on the technical solution of the present invention and provides detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need further definition and explanation in subsequent drawings. Some embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features described herein can be combined with each other.

[0030] Example

[0031] like Figure 1 As shown, a high-pressure gas pipeline H in a certain city passes through a subway branch line track and subway line F from north to south, and then reaches the gas gate station E. The gas pipeline H is subjected to severe interference from stray currents from the nearby subway.

[0032] When an external current is applied at gas gate station E to provide protection for the pipeline section of test pile #6, the protective current is released through the anode ground bed and needs to cross the subway running rail and the garage main line track to reach the pipeline section of test pile #6. At this time, the leakage current field of the running rail will interfere with the external current field, affecting the smooth arrival of the anode ground bed current at the gate station to the pipeline section of test pile #6.

[0033] To address the aforementioned problems, this embodiment provides a stray current elimination device for gas pipelines, including a cathodic protection system installed at the gas gate station E and a sacrificial anode buried at a predetermined distance along the gas pipeline section; wherein, as... Figure 2 As shown, a diode is connected in series between the sacrificial anode and the gas pipeline as a polarity drain, allowing only unidirectional current flow from the gas pipeline to the sacrificial anode to the soil.

[0034] Multiple diodes are connected in series between the sacrificial anode and the gas pipeline, and each series branch is equipped with an on / off switch. When a single diode breaks down, the branch containing the broken-down diode can be shut off in time, preventing reverse current from occurring due to unidirectional control failure between the gas pipeline, sacrificial anode, and soil, which would affect the stray current elimination effect, thus improving reliability.

[0035] In this embodiment, multiple sacrificial anodes are provided, which can be arranged according to the relative positions of the gas pipeline and the subway line. Zinc anodes are selected as the sacrificial anodes.

[0036] In this embodiment, the gas pipeline is connected to the gas gate station through an insulating joint. The cathodic protection system includes an anode ground bed and a micro-controlled potentiostat installed at the gas gate station. The micro-controlled potentiostat outputs a constant current to the gas pipeline through the anode ground bed, and the constant current is 3 to 4 A.

[0037] In addition, the outer surface of the gas pipeline is equipped with an external anti-corrosion layer, which consists of three layers of PE, further enhancing the protective effect.

[0038] Next, the effectiveness of the stray current elimination device for gas pipelines designed in this embodiment will be verified.

[0039] 1. Only introduce a cathodic protection system

[0040] According to the measurement method of cathodic protection parameters of buried steel pipelines specified in GB / T 21246 standard, the on-current potential of the pipeline section was measured using a long-life copper / saturated copper sulfate reference electrode (CSE) and a test piece of the same material as the pipeline. At the same time, the off-current potential of the test piece was collected by continuously cycling 12s on and 3s off using a relay.

[0041] like Figure 3 As shown, during subway operation, the on-state and off-state potentials of the pipeline section at test pile #6 exhibit periodic and severe fluctuations. During the day, the on-state potential fluctuates between -4.409 and 2.465V, while the off-state potential fluctuates between -1.074 and -0.357V. At night, when the subway is not in operation, the on-state potential stabilizes at -1.045V, and the off-state potential stabilizes at -0.765V, failing to meet the -850mV cathodic protection criterion. Gas pipeline H is severely affected by the dynamic DC stray current from the subway, requiring additional protective measures. Clearly, even with existing impressed current protection, the gas pipeline at this location still suffers from strong interference from subway operation.

[0042] 2. Sacrificial anode

[0043] Sacrificial anodes are zinc anodes buried near the pipeline during pipeline construction.

[0044] Figure 4This section presents the on- and off-potential data of the test pile before and after the sacrificial anode discharge. After adding the sacrificial anode, the amplitude of the on-potential fluctuation significantly decreased, while the amplitude of the off-potential fluctuation did not change significantly over a short period. For the time series data of such rapidly fluctuating on- and off-potentials, the most positive and negative 5% of the diurnal fluctuation potential were statistically analyzed to observe the fluctuation characteristics of the on- and off-potentials before and after connecting the sacrificial anode. The results are shown in […]. Figure 5 Current potential Avg max5％ When the potential level drops from 1V to 0V, the current-carrying potential Avg min5％ As the potential level drops from -2V to -1.5V, both the positive and negative biases of the on-state potential decrease. Meanwhile, the off-state potential (Avg) decreases over several days after the sacrificial anode drains. max5％ The potential level was reduced from -0.6V to -0.7V, which improved the positive bias of the power-off potential.

[0045] 3. A diode is connected in series between the sacrificial anode and the gas pipeline as a polarity drain.

[0046] Stray currents can enter the pipe through the sacrificial anode, thereby increasing the total amount of stray current flowing into the pipe. To improve this problem, this embodiment uses a diode connected in series between the pipe and the sacrificial anode as a polarity drain, allowing only unidirectional current flow from the pipe to the sacrificial anode to the soil.

[0047] The following analysis examines the changes in the fluctuation amplitude and average value of the on-state and off-state potentials before and after the diode was installed.

[0048] like Figure 5 As shown, after adding the diode, the on / off potential of the pipeline shifted negatively. During the test period, the average on-state potential decreased from -0.964V to -1.270V, and the average off-state potential decreased from -0.786V to -0.857V. Further analysis of the daily fluctuation characteristics of the on / off potential before and after adding the diode is shown below. Figure 6 As shown, the current-carrying potential Avg max5％ No significant change, but the background value of the energizing potential and Avg min5％ Both are negatively offset; while the background value of the power outage potential and Avg max5％ Avg min5％ Both are clearly negatively biased, indicating that the diode can improve the situation of positive bias at the off-voltage potential to a certain extent.

[0049] The current change of the sacrificial anode before and after the installation of the polarity drain is as follows: Figure 7As shown, with only the sacrificial anode present, the anode output current is stable during subway shutdowns; however, during subway operation, the sacrificial anode output current fluctuates wildly, with current frequently flowing into and out of the sacrificial anode pipe. The maximum amplitude of the positive current is 1205mA, and the maximum amplitude of the negative current is -635mA. After adding the diode, there is no negative current from the sacrificial anode, and the fluctuation amplitude of the positive output current from the sacrificial anode also decreases, with the maximum value dropping to 848mA.

[0050] This is because the voltage drop across the diode increases the internal resistance of the sacrificial anode-channel circuit. For example... Figure 8 As shown, without a diode, the output current of the sacrificial anode fluctuates synchronously with the energizing potential. However, after adding a diode, when the energizing potential is negatively biased to the point of being equal to the anode potential, there is no negative current in the sacrificial anode, thus preventing stray current from flowing into the pipe through the sacrificial anode.

[0051] In summary, sacrificial anodes can provide a certain degree of protection for pipelines. After installing polarity drainers, they can effectively suppress the negative current introduced into the gas pipeline through sacrificial anodes.

[0052] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model 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 this invention, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A stray current elimination device for gas pipelines, characterized in that, This includes cathodic protection systems installed at gas gate stations and sacrificial anodes buried at set distances along gas pipelines; A diode is connected in series between the sacrificial anode and the gas pipeline as a polarity drain, allowing only unidirectional current flow from the gas pipeline to the sacrificial anode to the soil.

2. The stray current elimination device for gas pipelines according to claim 1, characterized in that, Multiple diodes are connected in series between the sacrificial anode and the gas pipeline.

3. The stray current elimination device for gas pipelines according to claim 1, characterized in that, Each series branch is equipped with an on / off switch.

4. A stray current elimination device for gas pipelines according to claim 1, characterized in that, The cathodic protection system includes an anode ground bed and a micro-controlled potentiostat installed at the gas gate station. The micro-controlled potentiostat outputs a constant current to the gas pipeline through the anode ground bed.

5. A stray current elimination device for gas pipelines according to claim 4, characterized in that, The constant current is 3 to 4 A.

6. A stray current elimination device for gas pipelines according to claim 1, characterized in that, The gas pipeline is connected to the gas gate station via an insulating joint.

7. A stray current elimination device for gas pipelines according to claim 1, characterized in that, The device is equipped with multiple sacrificial anodes, which are arranged according to the relative positions of the gas pipeline and the subway line.

8. A stray current elimination device for gas pipelines according to claim 1, characterized in that, The sacrificial anode is a zinc anode.

9. A stray current elimination device for gas pipelines according to claim 1, characterized in that, The outer surface of the gas pipeline is provided with an external anti-corrosion layer.

10. A stray current elimination device for gas pipelines according to claim 9, characterized in that, The external anti-corrosion layer is a 3-layer PE external anti-corrosion layer.

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