阅读说明：本技术 线路管道阴极保护干扰处理方法 (Line pipeline cathode protection interference processing method ) 是由 孙冰冰 李岚鑫 高桂飞 赵康 张平平 张楠 李振军 田野 邢占元 徐赫 李琛 于 2019-12-04 设计创作，主要内容包括：一种线路管道阴极保护干扰处理方法,步骤包括：在绝缘接头一侧的土壤中埋设阳极地床,在场站外的土壤中沿着场站外的管道由内向外依次设置第一参比电极和第二参比电极,实时检测到的通电电位V<Sub>on_1</Sub>和V<Sub>on_2</Sub>,计算当前的通电电位差ΔV<Sub>on</Sub>,恒电位仪的输出电流由零点开始逐渐增加输出,直至ΔV<Sub>on</Sub>为0本发明的线路管道阴极保护干扰处理方法,单独设置恒电位仪,并使该恒电位仪通过阳极地床释放电流,产生的阳极电压场抵消干扰源附近的阴极电压场,从而消除场站内区域阴极保护设备放电对场站外管线阴极保护造成的干扰,从根本上消除干扰问题,处理效果好,而且处理方法简单,操作容易,降低对人员的技术要求。(A cathode protection interference processing method for a line pipeline comprises the following steps: burying an anode ground bed in the soil on one side of the insulating joint, sequentially arranging a first reference electrode and a second reference electrode in the soil outside the field station from inside to outside along a pipeline outside the field station, and detecting the electrified potential V in real time on_1 And V on_2 Calculating the present current energizing potential difference DeltaV on The output current of the constant potential rectifier gradually increases from zero to delta V on The invention is 0 line pipe cathode protection interference processing method, setting potentiostat separately, and making the potentiostat release current through anode ground bed, the generated anode voltage field counteracts the cathode voltage field near the interference source, thus eliminating the interference caused by cathode protection of regional cathode protection equipment discharging in the station to the outside pipeline cathode protection of the station, eliminating the interference problem fundamentally, the processing effect is good, and the processing method is simple, easy to operate, and reducing the technical requirements for personnel.)

1. A cathode protection interference processing method for a line pipeline is characterized by comprising the following steps:

burying an anode ground bed in soil on one side of the insulating joint, connecting the anode ground bed with the anode of the potentiostat through a lead, and connecting the cathode of the potentiostat with a pipeline in the station;

sequentially arranging a first reference electrode and a second reference electrode in soil outside a station from inside to outside along a pipeline outside the station, wherein the first reference electrode is arranged on one side of the inner end of the pipeline outside the station;

the remote terminal is connected with the first reference electrode and the second reference electrode through leads, and the first reference electrode and the second reference electrode respectively detect the electrified potential V in real time_{on_1}And V_{on_2}Uploading to a remote terminal;

the remote terminal calculates the current electrified potential difference delta V in real time_on，ΔV_on＝V_{on_1}-V_{on_2}；

The output current of the constant potential rectifier gradually increases from zero to delta V_onIs 0.

2. The method of claim 1, wherein the potential distribution pattern centered on the insulated joint is obtained by a close-spaced potential test method;

the anode ground bed adopts an anode strip which is arranged along a potential strip with the most positive potential value in the potential distribution diagram.

3. The method for processing the line pipe cathodic protection interference according to claim 2, wherein the step of the close-spaced potential test method is as follows:

taking the insulated joint as a center, and respectively selecting five directions which are parallel to the pipeline, perpendicular to the pipeline and at 45 degrees relative to the pipeline for potential detection;

a plurality of detection points are arranged in each direction, and the distance between adjacent detection points in the same direction is A;

and (3) carrying out potential detection on the detection points in each direction one by one from inside to outside by using the reference electrode, and connecting the detection points with the same potential through a smooth curve to obtain a potential distribution diagram.

4. The method as claimed in claim 3, wherein the distance A is 3-5 m.

5. The method as claimed in claim 3, wherein when the detection points are individually detected, if the potentials of two adjacent detection points in the same direction are the same, the detection is stopped.

6. The line pipe cathod protection interference treatment method of claim 2, wherein said second reference electrode is disposed in a potential band of a potential profile having a most negative potential value.

7. The method as claimed in claim 1, wherein a space is provided between the anode bed and the pipeline.

Technical Field

The invention belongs to the technical field of cathodic protection and corrosion prevention, and particularly relates to a cathodic protection interference processing method for a circuit pipeline.

Background

At present, regional cathode protection is widely applied to corrosion and protection of most domestic oil and gas transmission stations, large-scale tank areas, urban natural gas stations, underground gathering and transportation pipe networks of refineries and the like. The areas need to be connected with long-distance conveying pipelines to convey produced, manufactured or stored oil, and the conveying pipelines also need to be protected by cathodes for corrosion prevention.

The vast majority of domestic long-distance pipelines adopt a forced current cathodic protection mode, and a power supply (constant potential rectifier) control mode of a cathodic protection system generally adopts a constant potential rectifier control mode. The control principle is as follows: the reference electrode for control is arranged on the outer side of an insulating joint (a station and line electric insulating device), the reference electrode measures the protection potential (a feed point) of a line pipeline at the position in real time and feeds a value back to the constant potential instrument, the constant potential instrument compares the difference value of the potential and a preset target potential, and the output current is increased or reduced in real time through an internal control circuit, so that the feedback point is infinitely close to the preset potential. In the above control logic, the reference potential of the control point directly affects the output of the line cathodic protection system, which means that if the reference electrode is interfered by the external environment to cause potential deviation, the cathodic protection effect of the whole line will be affected.

Regional cathodic protection versus line cathodic protection interference types generally take two forms. As shown in fig. 1, when the anode ground bed used for the cathodic protection of the station yard area is close to the cathode protection feed point of the line, in many cases, a part of the area protection current (interference current) will flow in the vicinity of the feed point and flow out at a distance, at this time, the cathode polarization of the feed position pipeline increases, the protection potential negatively shifts, and the output of the potentiostat of the line decreases, resulting in a shortened protection distance. As shown in fig. 2, when the far-anode ground bed is used for regional cathodic protection, an interference current flows in from the far end of the line and flows out from the vicinity of the feed point, which may cause the degree of cathodic polarization of the feed point pipeline to decrease or cause anodic polarization, the potential shifts in the positive direction, the output of the line potentiostat increases, and the far-end line is over-protected.

As known from the principle of cathodic protection, cathodic protection mainly utilizes an auxiliary anode and supplies current, which flows from a protected pipeline to cause cathodic polarization of the pipeline, thereby inhibiting corrosion. From this point of view, although excessive current flowing into the pipeline causes over-protection, resulting in hydrogen embrittlement or peeling of the anticorrosive layer, the damage is reported to be far less than that caused by metal corrosion due to current flowing out. In addition, the method for dealing with the anode electric field interference of fig. 1 can be solved by only properly adjusting the position of the regional cathodic protection near the anode or the output current magnitude thereof.

The current handling of the cathodic voltage field disturbance of the class of fig. 2 is mainly in the following ways:

(1) carrying out a close-spaced potential test on an off-site trunk line, and transferring a control point of an off-site cathodic protection system to an undisturbed position;

(2) processing the control point, and installing a drainage electrode to reduce or eliminate additional polarization or depolarization caused by interference current;

(3) the protection system outside the station adopts constant current control;

the above interference elimination method has the following disadvantages from the effects and implementation methods:

(1) when the control point is transferred to an undisturbed position, the cathodic protection of the circuit can be recovered to be normal, but the disturbed section still has the phenomenon that the current outflow potential is biased to be positive, and the interference problem is not solved fundamentally;

(2) the way of installing the drainage electrode to the control point is in principle an effective way, but it is currently common practice to install a sacrificial anode near the control point or in the disturbed section. The sacrificial anode can provide cathodic protection current for the interference pipe section to a certain extent to inhibit the current from flowing out, but the current amount for regional cathodic protection is large, the output current of the sacrificial anode is very limited, and the sacrificial anode can be completely inhibited and is difficult to control. In addition, the integral grounding resistance of the protected pipe section is reduced by burying the sacrificial anode, and the current outflow path is increased;

(3) as with the transfer control point, although the off-station protection system adopts constant current control, the far-end cathodic protection can be normal, the near-end interference cannot be suppressed, and the line cathodic protection potential cannot be controlled in a constant current operating state, which requires continuous monitoring and adjustment, thus having a high professional level for managers and increasing the management cost.

Disclosure of Invention

Aiming at the problems that the interference processing method in the prior art cannot be eliminated fundamentally, the effect is poor, the requirement on personnel is high and the like due to the fact that the interference of the near-end outflow and the far-end inflow is caused to the line pipeline by regional cathode protection, the invention provides the line pipeline cathode protection interference processing method which is simple in operation, good in effect and capable of eliminating the interference fundamentally.

In order to achieve the purpose, the invention adopts the technical scheme that:

a cathode protection interference processing method for a line pipeline comprises the following steps:

burying an anode ground bed in soil on one side of the insulating joint, connecting the anode ground bed with the anode of the potentiostat through a lead, and connecting the cathode of the potentiostat with a pipeline in the station;

sequentially arranging a first reference electrode and a second reference electrode in soil outside a station from inside to outside along a pipeline outside the station, wherein the first reference electrode is arranged on one side of the inner end of the pipeline outside the station;

the remote terminal is connected with the first reference electrode and the second reference electrode through leads, and the first reference electrode and the second reference electrode respectively detect the electrified potential V in real time_{on_1}And V_{on_2}Uploading to a remote terminal;

the remote terminal calculates the current electrified potential difference delta V in real time_on，ΔV_on＝V_{on_1}-V_{on_2}；

The output current of the constant potential rectifier gradually increases from zero to delta V_onIs 0.

Preferably, the method for processing the line pipe cathodic protection interference according to claim 1, wherein a potential distribution diagram centering on the insulation joint is obtained by a closely spaced potential test method;

the anode ground bed adopts an anode strip which is arranged along a potential strip with the most positive potential value in the potential distribution diagram.

Preferably, the closely spaced potential test method comprises the following steps:

taking the insulated joint as a center, and respectively selecting five directions which are parallel to the pipeline, perpendicular to the pipeline and at 45 degrees relative to the pipeline for potential detection;

a plurality of detection points are arranged in each direction, and the distance between adjacent detection points in the same direction is A;

and (3) carrying out potential detection on the detection points in each direction one by one from inside to outside by using the reference electrode, and connecting the detection points with the same potential through a smooth curve to obtain a potential distribution diagram.

Preferably, the distance a is 3 to 5 meters.

Preferably, when the potential detection is performed on the detection points one by one, the detection is stopped when the potentials of two adjacent detection points in the same direction are the same.

Preferably, the second reference electrode is provided in a potential band having a most negative potential value in the potential distribution diagram.

Preferably, a space is arranged between the anode ground bed and the pipeline.

Compared with the prior art, the invention has the advantages and positive effects that:

1. the line pipe cathode protection interference processing method of the invention is characterized in that the potentiostat is independently arranged, the potentiostat releases current through the anode ground bed, and the generated anode voltage field counteracts the cathode voltage field near the interference source, thereby eliminating the interference caused by the discharge of the regional cathode protection equipment in the station to the cathode protection of the outer pipeline of the station, fundamentally eliminating the interference problem, having good processing effect, simple processing method and easy operation, and reducing the technical requirements on personnel.

2. The potential distribution diagram is measured by a close-spaced potential test method, so that the region with the strongest cathode voltage field can be obtained, the anode ground bed is arranged in the region, the generated anode voltage field can fully offset the cathode voltage field of an interference source, and blind spots are avoided. The anode ground bed adopts a strip structure, so that the anode ground bed can be fully and uniformly distributed in an area with the strongest cathode voltage field, and the interference treatment effect is improved.

3. The close-spaced potential testing method selects 5 directions, can measure the potential distribution diagram meeting the precision requirement with the least measuring times, and has higher working efficiency. When the measurement result in the same direction is not changed, the detection is stopped, unnecessary workload is reduced, and the working efficiency is improved.

4. The second reference electrode is arranged in the region with the smallest potential in the potential distribution diagram, so that the span of the first reference electrode and the second reference electrode can fully cover the cathode voltage field represented by the whole potential distribution diagram, the voltage difference generated by the cathode voltage field can be more accurately reflected, and the elimination of the cathode voltage field can be accurately shown when the voltage difference between the first reference electrode and the second reference electrode is 0.

5. An interval is arranged between the anode ground bed and the pipeline, so that the influence of the discharge of the anode ground bed on the potential on the pipeline is avoided, and the effect of cathode protection of the pipeline is ensured.

Drawings

FIG. 1 is a diagram illustrating a first interference pattern of regional cathodic protection to line cathodic protection in the prior art;

FIG. 2 is a diagram of a second interference pattern of regional cathodic protection to line cathodic protection in the background art;

FIG. 3 is a layout diagram of the apparatus for the interference processing method of cathodic protection of line pipes according to the present invention;

FIG. 4 is a schematic view of measurement point selection for a close-spaced potentiometric assay;

FIG. 5 is a graph of potential distribution according to an embodiment of the present invention;

FIG. 6 is a graph of a potential test according to an embodiment of the present invention;

in the above figures: 1.1, a first pipeline; 1.2, a second pipeline; 2. an insulated joint; 3. a potentiostat; 4. an anode ground bed; 5.1, a first reference electrode; 5.2, a second reference electrode; 6. a remote terminal; 7. and detecting points.

Detailed Description

The invention is described in detail below by way of exemplary embodiments. It should be understood, however, that elements, structures and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

In the description of the present invention, it should be noted that the terms "inside", "outside", "upper", "lower", "front", "rear", and the like indicate orientations or positional relationships based on positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The first pipeline 1.1 in the station is connected with the second pipeline 1.2 outside the station through the insulating joint 2, and the insulating joint 2 plays an important protection role in sealing and preventing electrochemical corrosion.

As shown in fig. 3 to 6, the present invention provides a method for processing line pipe cathodic protection interference, which is performed according to the following steps.

A potentiostat 3 for eliminating interference is independently arranged, an anode ground bed 4 is buried in soil on one side of the insulating joint 2, the anode ground bed 4 is connected with the anode of the potentiostat 3 through a lead, and the cathode of the potentiostat 3 is connected with a first pipeline 1.1 in a station.

In the soil outside the station, along the direction that second pipeline 1.2 was laid outside the station, set up first reference electrode 5.1 and second reference electrode 5.2 from inside to outside in proper order.

The first reference electrode 5.1 is arranged at one side of the inner end of the second pipeline 1.2 and close to the insulated joint 2; a second reference electrode 5.2 is located distally, away from the insulated joint 2.

The first reference electrode 5.1 detects the current energizing potential V of the corresponding position_{on_1}The second reference electrode 5.2 detects the current energizing potential V of the corresponding position_{on_2}。

The remote terminal 6 is connected with the first reference electrode 5.1 and the second reference electrode 5.2 through leads, and the detected V is_{on_1}And V_{on_2}Uploading to the remote terminal 6, the remote terminal 6 calculating the current energizing potential difference delta V in real time_onI.e. the potential difference, DeltaV, of the applied potentials at the same time measured by the two reference electrodes_on＝V_{on_1}-V_{on_2}。

The output current of the constant potential rectifier 3 is gradually increased from zero to output until delta V _on0, the two reference electrodes 5.1 and 5.2 are electrified at the same time and have the same potential, and the constant potential instrument 3 discharges electricity in the soil on one side of the insulated joint 2The anode voltage field of (2) can counteract the cathode voltage field near the interference source, and eliminate the interference of the pipeline outside the station.

Because the cathode voltage field near the interference source is not a uniform voltage field, if the anode bed 4 connected with the potentiostat 3 is not located at the position where the cathode voltage field is strongest, the anode voltage field generated by the discharge of the anode bed 4 cannot completely cover the area where the cathode voltage field is located, so that the cathode voltage field at partial positions is not completely counteracted, and the interference is not completely eliminated.

In order to avoid the above problem, before the anode bed 4 is arranged, a potential distribution diagram centering on the insulated contact 2 is obtained by a close-spaced potential test method.

As shown in fig. 4, the potential detection is performed in five directions, which are parallel to the pipe, perpendicular to the pipe, and 45 degrees with respect to the pipe, respectively, on the horizontal plane with the insulated joint 2 as the center.

A plurality of detection points 7 are arranged in each direction, and the distance between adjacent detection points 7 in the same direction is A.

Potential detection is performed one by one at the detection points 7 in each direction from the inside to the outside by using the reference electrode, and a potential test graph as shown in fig. 6 is obtained.

The detection points are indicated on a plan view, and the detection points having the same potential are connected by a smooth curve to obtain a potential distribution diagram as shown in fig. 5.

The region between two adjacent smooth curves in the potential distribution diagram forms a potential band, and the potential level of each position in the same potential band is the same.

The anode ground bed adopts an anode strip with a strip structure, and the anode strip is arranged in a potential strip with the most positive potential value in the potential distribution diagram and is arranged along the distribution direction of the potential strip.

The potential value is most positive, namely the potential value is maximum, and the potential value is most negative, namely the potential value is minimum.

As shown in fig. 5, the potential zone with the most positive potential value is located in the direction directly north of the insulated joint, and the anode zone is perpendicular to the second pipe 1.2 outside the station and extends to the north.

In order to ensure the density of the detection points, the distance between adjacent detection points in the same direction is 3-5 meters.

When the detection points are subjected to potential detection one by one, if the potentials of two adjacent detection points in the same direction are the same, the detection is stopped, and other detection points in the direction do not need to be detected, so that the workload is reduced, and the working efficiency is improved.

In order to make the potential difference between the two reference electrodes 5.1 and 5.2 sufficiently reflect the interference of the cathode voltage field, the second reference electrode 5.2 is arranged in the potential band with the most negative potential value in the potential distribution diagram, so that the span of the first reference electrode and the second reference electrode can sufficiently cover the whole area of the potential distribution diagram, and the elimination of the cathode voltage field can be accurately indicated when the voltage difference between the two electrodes is 0.

An interval is arranged between the anode ground bed 4 and the pipeline, so that the influence of the discharge of the anode ground bed on the potential on the pipeline is avoided, and the effect of cathodic protection of the pipeline is ensured.