An on-line detection method and system for the corrosion of chemical pipelines

Abstract

The present invention discloses an on-line detection method and system for the corrosion of chemical pipelines, which relates to the technical field of corrosion detection of chemical pipelines, and includes the following steps: measuring the wall thickness of the chemical pipeline by ultrasonic phased array; analyzing the corrosion rate at the weakest part of the wall thickness to obtain a reference rate, and at the same time analyzing the overall corrosion rate of the chemical pipeline to obtain an overall rate; analyzing the relationship between the change of the reference rate and the working temperature, and at the same time predicting the reference rate, and then predicting the remaining life of the chemical pipeline based on the prediction result; monitoring whether the change of the overall rate is abnormal; The present invention is used to solve the problems existing in the existing chemical pipeline corrosion detection technology, that is, the analysis of the corrosion rate is not comprehensive enough and the calculation of the remaining life is not reasonable enough, resulting in a longer predicted result than the actual result when predicting the remaining life of the chemical pipeline, and there are potential safety hazards.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical pipeline corrosion detection, and specifically to an on-line detection method and system for chemical pipeline corrosion. Background Art

[0002] The chemical pipeline corrosion detection technology refers to a technical system that systematically evaluates the corrosion state of pipeline materials caused by factors such as media, temperature, and pressure in the service environment through physical, chemical, or intelligent sensing means, and quantifies the degree of damage. Its core goal is to identify corrosion risks, predict remaining life, and guide maintenance decisions.

[0003] Existing chemical pipeline corrosion detection technologies usually analyze the corrosion rate of chemical pipelines based on the wall thickness, while ignoring other important factors that affect the corrosion rate. At the same time, when evaluating and predicting the remaining life of chemical pipelines, the consideration is not comprehensive enough. The corrosion rates and corrosion degrees in different parts of the chemical pipeline are different. If the corrosion rate of the entire chemical pipeline is used for evaluation and prediction, the predicted remaining life will be longer than the actual one, which will pose a great safety hazard. For example, in the patent application with the publication number CN118501034A, a high-precision detection method and system for corrosion resistance testing of gas pipelines are disclosed. This solution does not consider all the factors that affect the corrosion rate completely, and does not consider the weak points of the pipeline when predicting the life of the pipeline. Therefore, the actual corrosion resistance time calculated is not the true corrosion resistance time of the pipeline. Existing chemical pipeline corrosion detection technologies also have problems such as incomplete analysis of the corrosion rate and unreasonable calculation of the remaining life, resulting in a longer predicted result than the actual result when predicting the remaining life of chemical pipelines, and there are safety hazards. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the existing technology to some extent. By using ultrasonic phased array to measure the wall thickness of chemical pipelines, then based on the wall thickness of different regions inside the chemical pipeline, constructing a thickness change distribution map and analyzing the corrosion rate at the weakest part of the wall thickness in combination with the working temperature to obtain a reference rate. At the same time, analyzing the overall corrosion rate of the chemical pipeline to obtain an overall rate. Then, based on the historical reference rate and working temperature, analyzing the temperature-rate relationship function, and then predicting the reference rate of the chemical pipeline based on the temperature-rate relationship function, and predicting the remaining life of the chemical pipeline at the same time. During this period, real-time monitoring whether the change of the overall rate is abnormal, so as to solve the problems that existing chemical pipeline corrosion detection technologies have incomplete analysis of the corrosion rate and unreasonable calculation of the remaining life, resulting in a longer predicted result than the actual result when predicting the remaining life of chemical pipelines, and there are safety hazards.

[0005] To achieve the above object, in a first aspect, the present invention provides an on-line detection method for the corrosion of chemical pipelines, comprising the following steps:

[0006] Measure the wall thickness of the chemical pipeline by ultrasonic phased array;

[0007] Based on the wall thickness of different regions inside the chemical pipeline, analyze the corrosion rate at the weakest part of the wall thickness to obtain a reference rate, and at the same time analyze the overall corrosion rate of the chemical pipeline to obtain an overall rate;

[0008] Obtain the historical reference rate, analyze the relationship between the change of the reference rate and the working temperature in combination with the working temperature of the chemical pipeline, predict the reference rate at the same time, and then predict the remaining life of the chemical pipeline based on the prediction result;

[0009] Monitor whether the change of the overall rate is abnormal.

[0010] Further, measuring the wall thickness of the chemical pipeline by ultrasonic phased array includes the following sub-steps:

[0011] Select a detection starting point on the chemical pipeline, and starting from the detection starting point, install an ultrasonic sensor on the chemical pipeline every first interval distance;

[0012] Set the sampling frequency of the ultrasonic sensor to the standard frequency;

[0013] Statistically analyze the measured wall thickness, and at the same time record the distance corresponding to the wall thickness, marked as the detection distance, where the detection distance represents the length from the detection starting point, and the wall thickness represents the minimum value of the thickness within a circular area at the detection distance.

[0014] Further, based on the wall thickness of different regions inside the chemical pipeline, analyzing the corrosion rate at the weakest part of the wall thickness to obtain a reference rate, and at the same time analyzing the overall corrosion rate of the chemical pipeline to obtain an overall rate includes the following sub-steps:

[0015] Based on the wall thickness of different regions inside the chemical pipeline, construct a thickness change distribution map and analyze the corrosion rate at the weakest part of the wall thickness in combination with the working temperature to obtain a reference rate;

[0016] Analyze the overall corrosion rate of the chemical pipeline to obtain an overall rate.

[0017] Further, based on the wall thickness of different regions inside the chemical pipeline, constructing a thickness change distribution map and analyzing the corrosion rate at the weakest part of the wall thickness in combination with the working temperature to obtain a reference rate includes the following sub-steps:

[0018] Taking the detection distance as the X-axis and the pipe wall thickness as the Y-axis, a plane rectangular coordinate system is established, named the thickness change distribution diagram. The pipe wall thickness is entered into the thickness change distribution diagram according to the detection distance.

[0019] The coordinate points in the thickness change distribution diagram are connected in the form of a smooth curve, and the curve obtained by connection is named the thickness change curve.

[0020] Find the lowest point in the thickness change curve, mark it as the weak point, and name the pipe wall thickness corresponding to the weak point as the weak thickness.

[0021] Obtain the range of the working temperature of the chemical pipeline, named the temperature range. Make a preset equal division of the temperature range, and mark the different temperature ranges divided by the preset equal division as T n , where n is a non-zero natural number and n is the serial number of T.

[0022] For any T n , when the working temperature of the chemical pipeline is within T n , start timing. When the working temperature changes and the n of the T where the working temperature is located n changes, stop timing. Name the number of days when the recorded working temperature is maintained within T n as the evaluation period, represented by the symbol t.

[0023] After stopping timing, the working temperature jumps to another T n , and start timing again, recording the next evaluation period.

[0024] Each time when starting timing, record the weak thickness once, mark it as H1. Each time when ending timing, record the weak thickness once, mark it as H2. Calculate H1 - H2, and mark the calculation result as ΔH, named the thickness difference.

[0025] Calculate ΔH / t, mark the calculation result as the reference rate, and at the same time record the T n .

[0026] Furthermore, analyzing the corrosion rate of the whole chemical pipeline, the overall rate is obtained including the following sub-steps:

[0027] When the working temperature is within T n , use the ER corrosion rate detection method to detect the corrosion rate of the whole chemical pipeline, and obtain the detection rate.

[0028] Calculate the average value of the detection rate within the corresponding evaluation period to obtain the overall rate.

[0029] Further, obtain the historical reference rate, analyze the relationship between the change of the reference rate and the working temperature in combination with the working temperature of the chemical pipeline, and at the same time predict the reference rate, and then predict the remaining life of the chemical pipeline based on the prediction result, including the following sub-steps:

[0030] Analyze the temperature-rate relationship function based on the historical reference rate and the working temperature;

[0031] Predict the reference rate of the chemical pipeline based on the temperature-rate relationship function, and at the same time predict the remaining life of the chemical pipeline.

[0032] Further, analyzing the temperature-rate relationship function based on the historical reference rate and the working temperature includes the following sub-steps:

[0033] Obtain the reference rate in the historical record, mark it as the historical rate, and at the same time obtain the T corresponding to the historical rate n , name it the historical range, and mark it as HT n ;

[0034] Each HT n contains different numbers of historical rates. Taking HT n as the horizontal axis and the historical rate as the vertical axis, establish a plane rectangular coordinate system, name it the temperature-rate relationship diagram, and input HT n and the corresponding historical rate into the temperature-rate relationship diagram;

[0035] Perform quadratic polynomial regression analysis on the temperature-rate relationship diagram, and name the regression function obtained as the temperature-rate relationship function.

[0036] Further, predicting the reference rate of the chemical pipeline based on the temperature-rate relationship function and predicting the remaining life of the chemical pipeline at the same time include the following sub-steps:

[0037] Obtain the T to which the working temperature of each day in the past year belongs n , and at the same time record the duration of the working temperature continuously in T n , mark it as R(S,n), and R(S,n) represents that the working temperature of the chemical pipeline has been in T for S consecutive days n ;

[0038] Obtain the R(S,n) in the past year, and sort and number R(S,n) in chronological order, represented by the symbol K i , where i is a non-zero natural number and i is the serial number of K. Mark the S corresponding to K i as S i ;

[0039] Mark the T corresponding to K i as T nSubstitute into the temperature-rate relationship function, and mark the calculated reference rate as G. i ;

[0040] Obtain the minimum limit value of the wall thickness of the chemical pipeline, name it the minimum thickness, set a constant m, where m is initially 1, obtain the current weak thickness of the wall thickness, and mark it as F;

[0041] Through the formula Calculate the predicted thickness, where L is the predicted thickness;

[0042] Compare the predicted thickness with the minimum thickness. If the predicted thickness is less than or equal to the minimum thickness, output a life-ending signal; otherwise, output a continue prediction signal;

[0043] If the continue prediction signal is output, increment m by one and re-analyze until the life-ending signal is output;

[0044] If the life-ending signal is output, obtain the current value of m, mark it as M, and calculate the sum of S when i is less than or equal to M i Mark it as the remaining life.

[0045] Furthermore, monitoring whether the change in the overall rate is abnormal includes the following sub-steps:

[0046] Real-time monitor the overall rate, mark it as the real-time rate, obtain the overall rate of the previous evaluation period, represented by the symbol C1, mark it as the previous rate, represented by the symbol C2;

[0047] Calculate C1 / C2, and mark the calculation result as the rate increase;

[0048] Compare the rate increase with the first increase threshold. If the rate increase is less than the first increase threshold, output a normal increase signal; otherwise, output an abnormal increase signal;

[0049] If the abnormal increase signal is output, send a pipeline abnormality warning.

[0050] In a second aspect, the present invention provides an on-line corrosion detection system for chemical pipelines, including a thickness measurement module, a rate calculation module, a life prediction module, and a rate monitoring module; the thickness measurement module, the rate calculation module, and the rate monitoring module are respectively connected to the life prediction module for data connection;

[0051] The thickness measurement module is used to measure the wall thickness of the chemical pipeline by ultrasonic phased array;

[0052] The rate calculation module is used to analyze the corrosion rate at the weakest part of the wall thickness based on the wall thickness of different regions inside the chemical pipeline to obtain a reference rate, and at the same time analyze the overall corrosion rate of the chemical pipeline to obtain an overall rate;

[0053] The service life prediction module is used to obtain the historical reference rate, analyze the relationship between the change of the reference rate and the working temperature in combination with the working temperature of the chemical pipeline, predict the reference rate at the same time, and then predict the remaining service life of the chemical pipeline based on the prediction result;

[0054] The rate monitoring module is used to monitor whether the change of the overall rate is abnormal.

[0055] Advantages of the present invention: The present invention measures the wall thickness of the chemical pipeline by ultrasonic phased array, then constructs a thickness change distribution map based on the wall thickness of different regions inside the chemical pipeline, analyzes the corrosion rate at the weakest point of the wall thickness in combination with the working temperature to obtain the reference rate, and analyzes the overall corrosion rate of the chemical pipeline at the same time to obtain the overall rate. The advantage is that the working temperature will affect the corrosion rate of the chemical pipeline, and if there is a deviation in the corrosion rate analysis, it will lead to a deviation in the prediction of the remaining service life. Moreover, the remaining service life of the chemical pipeline has nothing to do with the overall corrosion rate of the pipeline, but is directly related to the corrosion rate and the weakest thickness at the weak point. Therefore, the remaining service life analyzed in this way is closer to the true value, improving the accuracy of the corrosivity detection of the chemical pipeline and the accuracy of the remaining service life analysis;

[0056] The present invention analyzes the temperature-rate relationship function based on the historical reference rate and the working temperature, then predicts the reference rate of the chemical pipeline based on the temperature-rate relationship function, and predicts the remaining service life of the chemical pipeline at the same time. During this period, it monitors in real time whether the change of the overall rate is abnormal. The advantage is that by analyzing the influence of temperature on the corrosion rate at the weak point and predicting the service life based on the working temperature throughout the year, the accuracy of the corrosivity detection of the chemical pipeline and the accuracy of the remaining service life analysis are further improved. Description of the Drawings

[0057] Figure 1 is the principle block diagram of the system of the present invention;

[0058] Figure 2 is the schematic diagram of the detection starting point and the detection distance of the present invention;

[0059] Figure 3 is the schematic diagram of the temperature-rate relationship diagram of the present invention;

[0060] Figure 4 is the step flow chart of the method of the present invention. Detailed Embodiments

[0061] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0062] Embodiment 1

[0063] Please refer to Figure 1 As shown, the present invention provides an on-line corrosion detection system for chemical pipelines, including a thickness measurement module, a rate calculation module, a life prediction module, and a rate monitoring module; the thickness measurement module, the rate calculation module, and the rate monitoring module are respectively connected to the life prediction module for data connection;

[0064] The thickness measurement module is used to measure the wall thickness of the chemical pipeline through ultrasonic phased array;

[0065] The thickness measurement module is configured with a thickness measurement strategy, and the thickness measurement strategy includes:

[0066] Select a detection starting point on the chemical pipeline. Starting from the detection starting point, install an ultrasonic sensor on the chemical pipeline every first interval distance;

[0067] Set the sampling frequency of the ultrasonic sensor to the standard frequency;

[0068] Please refer to Figure 2 As shown, statistically analyze the detected wall thickness, and at the same time record the distance corresponding to the wall thickness, marked as the detection distance. The detection distance represents the length from the detection starting point, and the wall thickness represents the minimum value of the thickness within a circular area at the detection distance;

[0069] In practical applications, the detection starting point is usually set at the inlet of the chemical pipeline. The first interval distance is set to 2m. There is no fixed requirement for the setting of the first interval distance. Generally, the smaller the first interval distance, the higher the detection accuracy, but the equipment cost will also increase. The specific setting is configured by the user himself. When the first interval distance is set to 2m, the detection accuracy is usually ±0.01mm, and the standard frequency is to collect data every 10s; as Figure 2 As shown, the detection starting point has been marked in Figure 2 There is an ellipse at the detection distance from the detection starting point. This ellipse is actually a side view of the inner circle of the chemical pipeline. The detection distances of all points within a circular range inside the chemical pipeline from the detection starting point are the same. Take the minimum value of the wall thickness among them to represent the wall thickness here. Because the smaller the wall thickness, the higher the corrosion rate here. At the same distance, analyzing the highest corrosion rate can be more reference-worthy.Figure 2 The boundary line of the lower half of the chemical industry pipeline shows an irregular shape, representing the corrosion of the inner wall of the chemical industry pipeline, while the upper half is a straight line, used to show the difference in the cross-sectional view when the inside of the chemical industry pipeline is corroded and uncorroded.

[0070] The rate calculation module is used to analyze the corrosion rate at the weakest part of the pipe wall thickness based on the pipe wall thickness in different regions inside the chemical industry pipeline to obtain a reference rate, and at the same time analyze the overall corrosion rate of the chemical industry pipeline to obtain an overall rate; the rate calculation module includes a reference rate calculation unit and an overall rate calculation unit;

[0071] The reference rate calculation unit is used to construct a thickness change distribution diagram based on the pipe wall thickness in different regions inside the chemical industry pipeline and analyze the corrosion rate at the weakest part of the pipe wall thickness in combination with the working temperature to obtain a reference rate;

[0072] The reference rate calculation unit is configured with a reference rate calculation strategy, and the reference rate calculation strategy includes:

[0073] Establish a plane rectangular coordinate system with the detection distance as the X-axis and the pipe wall thickness as the Y-axis, named the thickness change distribution diagram, and input the pipe wall thickness into the thickness change distribution diagram according to the detection distance;

[0074] Connect the coordinate points in the thickness change distribution diagram in the form of a smooth curve, and name the connected curve the thickness change curve;

[0075] Find the lowest point in the thickness change curve, mark it as the weak point, and name the pipe wall thickness corresponding to the weak point the weak thickness;

[0076] In practical applications, the thickness change distribution diagram is used to show the distribution of the pipe wall thickness inside the chemical industry pipeline. In the actual use process, only the minimum value in the pipe wall thickness needs to be found to determine the weak thickness, and the found weak thickness is 12.47 mm;

[0077] Obtain the range of the working temperature of the chemical industry pipeline, named the temperature range, perform a preset equal division on the temperature range, and mark the different temperature ranges divided by the preset equal division as T n , where n is a non-zero natural number and n is the serial number of T;

[0078] For any T n , when the working temperature of the chemical industry pipeline is within T n , start timing. When the working temperature changes and the n of the T n where the working temperature is located changes, stop timing, and name the number of days when the recorded working temperature is maintained within T n as the evaluation period, represented by the symbol t;

[0079] After stopping the timing, the working temperature jumps to another T n , and the timing starts again to record the next evaluation cycle;

[0080] Each time the timing starts, record the weak thickness once and mark it as H1. Each time the timing ends, record the weak thickness once and mark it as H2. Calculate H1 - H2, mark the calculation result as ΔH, and name it the thickness difference;

[0081] Calculate ΔH / t, mark the calculation result as the reference rate, and record the T corresponding to the reference rate obtained this time n ;

[0082] In practical applications, the temperature range obtained is [25°C, 70°C]. In this embodiment, the preset equal division setting is three equal divisions, and the temperature range is divided into three temperature levels: low, medium, and high. More ranges can be divided in practical applications, but it should be noted that it is necessary to ensure that each T n can be continuously maintained for more than two months to detect changes in the pipe wall thickness. Usually, the chemical pipeline operates for a long time, and each operation has a fixed temperature range, which may change during operations at different times; the divided T n , 1 ≤ n ≤ 3, where T1 to T3 are [25°C, 40°C], [40°C, 55°C], and [55°C, 70°C] in sequence. Taking T1 and T2 as an example, assume that the previous working temperature belongs to T2 and is maintained within [40°C, 55°C]. When it is detected that the working temperature is equal to 40°C, it still belongs to T2. Therefore, continue to record the evaluation cycle of T2. Only when it is detected that the working temperature does not belong to T2 and belongs to T1, then stop the timing of the evaluation cycle of T2 and start the timing of the evaluation cycle of T1, and record the weak thickness H1 once. The weak thickness H1 recorded this time is also the H2 recorded by the previous T2. Assume that the H1 recorded by T2 is 12.47 mm and H2 is 12.35 mm. The calculated thickness difference ΔH is 0.12 mm, and the evaluation cycle of T2 is 65 days. Further calculate the reference rate to be 0.001846 mm / day, which corresponds to the reference rate of T2;

[0083] The overall rate calculation unit is used to analyze the overall corrosion rate of the chemical pipeline to obtain the overall rate;

[0084] The overall rate calculation unit is configured with an overall rate calculation strategy, and the overall rate calculation strategy includes:

[0085] When the working temperature is at T n , use the ER corrosion rate detection method to detect the overall corrosion rate of the chemical pipeline to obtain the detection rate;

[0086] Calculate the average value of the detection rate within the corresponding evaluation period to obtain the overall rate.

[0087] In practical applications, the reference rate calculation unit is designed to calculate the corrosion rate of weak points, while the overall rate calculation unit is designed to calculate the overall corrosion rate of chemical pipelines. The overall corrosion rate can be detected by the existing ER corrosion rate detection method, and the technology is relatively mature. Therefore, no specific description is provided in this embodiment. When calculating the overall rate, for example, if the evaluation period of T2 this time is 65 days, and the ER corrosion rate detection method detects once a day, that is, there is a detection rate every day. Then divide the sum of the detection rates by 65 to calculate the average value of the detection rate, and the overall corrosion rate of the chemical pipeline during the evaluation period within the range where the working temperature is maintained at T2 can be obtained.

[0088] The remaining life prediction module is used to obtain the historical reference rate, analyze the relationship between the change of the reference rate and the working temperature in combination with the working temperature of the chemical pipeline, and at the same time predict the reference rate, and then predict the remaining life of the chemical pipeline based on the prediction result; the remaining life prediction module includes a relationship function calculation unit and a remaining life prediction unit.

[0089] The relationship function calculation unit is used to analyze the temperature-rate relationship function based on the historical reference rate and the working temperature.

[0090] The relationship function calculation unit is configured with a relationship function calculation strategy, and the relationship function calculation strategy includes:

[0091] Obtain the reference rate in the historical record, mark it as the historical rate, and at the same time obtain the T n corresponding to the historical rate, name it the historical range, and mark it as HT n ;

[0092] Please refer to Figure 3 as shown, each HT n contains different numbers of historical rates. Take HT n as the horizontal axis and the historical rate as the vertical axis to establish a plane rectangular coordinate system, name it the temperature-rate relationship diagram, and enter HT n and the corresponding historical rate into the temperature-rate relationship diagram.

[0093] Perform a quadratic polynomial regression analysis on the temperature-rate relationship diagram, and name the regression function as the temperature-rate relationship function.

[0094] In practical applications, HT n is T n each HT nContains different numbers of historical rates. For example, taking HT1 as an example, when the working temperature is within HT1 and changes from HT1 to HT2 or HT3, a historical rate is recorded. When the working temperature is within HT1 again, another historical rate can be recorded. Thus, according to the change of the working temperature, different numbers of historical rates can be recorded within each HT n and a temperature-rate relationship graph is constructed as shown in Figure 3 where the horizontal axis is HT n and HT n is a temperature range, which is not convenient to be used as the horizontal axis for calculation. Therefore, the median value of each HT n is taken as the horizontal axis, which is convenient for the subsequent calculation and substitution of the temperature-rate relationship function. Through quadratic polynomial regression analysis, the temperature-rate relationship function is obtained as Y = 0.0001×X 2 + 0.0076×X + 0.0764, where Y is the historical rate and X is HT n . For the convenience of calculation, the historical rates in the temperature-rate relationship graph are all converted from mm / day to mm / year;

[0095] The remaining life prediction unit is used to predict the reference rate of the chemical pipeline based on the temperature-rate relationship function and simultaneously predict the remaining life of the chemical pipeline;

[0096] The remaining life prediction unit is configured with a remaining life prediction strategy, and the remaining life prediction strategy includes:

[0097] Obtain the T n to which the working temperature of each day in the past year belongs, and at the same time record the duration of the continuous working temperature within T n , marked as R(S,n), where R(S,n) represents that the working temperature of the chemical pipeline has been within T n for S consecutive days;

[0098] Obtain the R(S,n) in the past year, and sort and number R(S,n) in chronological order, represented by the symbol K i , where i is a non-zero natural number and i is the serial number of K. Mark the S corresponding to K i as S i ;

[0099] In practical applications, taking 2023 as an example, from January 1, 2023 to March 6, 2023, the working temperature was within T2 for a total of 65 days, thus obtaining R(65, 2). Among them, S = 65 and n = 2. And so on, it is statistically obtained that K1 to K5 are R(65, 2), R(68, 1), R(72, 2), R(83, 3), and R(77, 1) in sequence. The value of i has no upper limit. When i is greater than 5, K1 to K5 are looped. That is, when i % 5 = 1, K i = K1; when i % 5 = 2, K i = K2; when i % 5 = 3, K i = K3; when i % 5 = 4, K i = K4; when i % 5 = 0, K i = K5; The S corresponding to K i is S i , such as S1 corresponding to K1 is 65 in R(65, 2);

[0100] Substitute the T i corresponding to K n into the temperature rate relationship function, and mark the calculated reference rate as G i ;

[0101] Obtain the lowest limit value of the wall thickness of the chemical pipeline, named the lowest thickness, set the constant m, with m initially being 1, obtain the current weak thickness of the wall thickness, and mark it as F;

[0102] Calculate the predicted thickness through the formula , where L is the predicted thickness;

[0103] Compare the predicted thickness with the lowest thickness. If the predicted thickness is less than or equal to the lowest thickness, output the end - of - life signal; otherwise, output the continue - prediction signal;

[0104] If the continue - prediction signal is output, increment m by 1 and re - analyze until the end - of - life signal is output;

[0105] If the end - of - life signal is output, obtain the value of the current m, mark it as M, and calculate the sum of S i when i is less than or equal to M, and mark it as the remaining life;

[0106] In practical applications, taking K1 as an example, the T n corresponding to K1 is T2, and T2 corresponds to 47.5 °C in the temperature rate relationship graph. That is, substitute 47.5 into Y = 0.0001×X 2 + 0.0076×X + 0.0764, and calculate that G1 is 0.663025 mm / year, corresponding to 0.001817 mm / day. The conversion result is retained to six decimal places. Calculate all Gs in the same way i, the minimum thickness obtained is 8 mm, F is 12.35 mm. When m = 1, the predicted thickness L is calculated to be 12.231895 mm. By comparison, the predicted thickness is greater than the minimum thickness, so a continue prediction signal is output. Set m + 1, at this time m = 2. Calculate the predicted thickness again and make a new judgment. Until m = 35, the predicted thickness is calculated to be 7.915311 mm. By comparison, the predicted thickness is less than the minimum thickness, so a life end signal is output. Calculate the sum of S when i is less than or equal to 35 i to obtain a remaining life of 2555 days. At this time, the remaining life is still not the final value but has a certain overflow. The chemical pipeline ends its life at m = 35, that is, during K 35 the life ends, and K 35 is the same as K5, both are within T1. When m = 34, the calculated predicted thickness is 8.005786 mm, and the difference from the minimum thickness is 0.005786 mm. In the T1 environment, the reference rate is 0.001175 mm / day. 0.005786 / 0.001175 = 4.9 days ≈ 5 days. That is, after K 34 , after another 5 days, the life of the chemical pipeline ends. When M = 34, the sum of S i is 2478, adding 5 gives a final remaining life of 2483 days. In actual use, there is a certain redundancy when replacing the chemical pipeline. Therefore, 2555 days can also be used as a reference for the remaining life. If the user needs a more accurate prediction, then perform subsequent calibration to obtain 2483 days.

[0107] The rate monitoring module is used to monitor whether the change in the overall rate is abnormal;

[0108] The rate monitoring module is configured with a rate monitoring strategy, and the rate monitoring strategy includes:

[0109] Monitor the overall rate in real time, mark it as the real-time rate, obtain the overall rate of the previous evaluation period, represented by the symbol C1, and mark it as the previous rate, represented by the symbol C2;

[0110] Calculate C1 / C2, and mark the calculation result as the rate increase;

[0111] Compare the rate increase with the first increase threshold. If the rate increase is less than the first increase threshold, then output a normal increase signal, otherwise output an abnormal increase signal;

[0112] If an abnormal increase signal is output, then send a pipeline abnormality warning;

[0113] In practical applications, the first increase threshold is the result of multiple experimental analyses. It is verified that the overall corrosion rate of the chemical pipeline cannot exceed the first increase threshold. If it exceeds, it means there is damage inside the chemical pipeline and it needs to be repaired in time.

[0114] Example 2

[0115] Please refer to Figure 4 as shown, the present invention provides an on-line detection method for the corrosion of chemical pipelines, including the following steps:

[0116] Step S1, measure the wall thickness of the chemical pipeline by ultrasonic phased array; Step S1 includes the following sub-steps:

[0117] Step S101, select a detection starting point on the chemical pipeline. Starting from the detection starting point, install an ultrasonic sensor on the chemical pipeline every first interval distance;

[0118] Step S102, set the sampling frequency of the ultrasonic sensor to the standard frequency;

[0119] Step S103, count the detected wall thickness, and at the same time record the distance corresponding to the wall thickness, marked as the detection distance. The detection distance represents the length from the detection starting point, and the wall thickness represents the minimum value of the thickness within a circular area at the detection distance;

[0120] Step S2, based on the wall thickness of different regions inside the chemical pipeline, analyze the corrosion rate at the weakest part of the wall thickness to obtain a reference rate, and at the same time analyze the overall corrosion rate of the chemical pipeline to obtain an overall rate; Step S2 includes the following sub-steps:

[0121] Step S201, based on the wall thickness of different regions inside the chemical pipeline, construct a thickness change distribution map and analyze the corrosion rate at the weakest part of the wall thickness in combination with the working temperature to obtain a reference rate;

[0122] Step S201 includes the following sub-steps:

[0123] Step S2011, establish a plane rectangular coordinate system with the detection distance as the X-axis and the wall thickness as the Y-axis, named the thickness change distribution map, and input the wall thickness into the thickness change distribution map according to the detection distance;

[0124] Step S2012, connect the coordinate points in the thickness change distribution map in the form of a smooth curve, and name the connected curve the thickness change curve;

[0125] Step S2013, find the lowest point in the thickness change curve, marked as the weak point, and name the wall thickness corresponding to the weak point the weak thickness;

[0126] Step S2014, obtain the range of the working temperature of the chemical pipeline, named the temperature range, perform a preset equal division on the temperature range, and mark the different temperature ranges divided by the preset equal division as T n, where n is a non - zero natural number and n is the serial number of T;

[0127] Step S2015, for any T n , when the working temperature of the chemical pipeline is within T n , start timing. When the working temperature changes and the n of the T where the working temperature is located n changes, stop timing. Name the number of days when the recorded working temperature is maintained within T n as the evaluation period, denoted by the symbol t;

[0128] Step S2016, after stopping timing, the working temperature jumps to another T n , start timing again, and record the next evaluation period;

[0129] Step S2017, each time starting to time, record the weak thickness once, marked as H1. Each time ending to time, record the weak thickness once, marked as H2. Calculate H1 - H2, and mark the calculation result as ΔH, named the thickness difference;

[0130] Step S2018, calculate ΔH / t, mark the calculation result as the reference rate, and at the same time record the T corresponding to the reference rate obtained in this calculation n ;

[0131] Step S202, analyze the corrosion rate of the whole chemical pipeline to obtain the overall rate;

[0132] Step S202 includes the following sub - steps:

[0133] Step S2021, when the working temperature is within T n , use the ER corrosion rate detection method to detect the corrosion rate of the whole chemical pipeline to obtain the detection rate;

[0134] Step S2022, calculate the average value of the detection rate within the corresponding evaluation period to obtain the overall rate;

[0135] Step S3, obtain the historical reference rate, analyze the relationship between the change of the reference rate and the working temperature in combination with the working temperature of the chemical pipeline, and at the same time predict the reference rate, and then predict the remaining life of the chemical pipeline based on the prediction result; Step S3 includes the following sub - steps:

[0136] Step S301, analyze the temperature - rate relationship function based on the historical reference rate and the working temperature;

[0137] Step S301 includes the following sub - steps:

[0138] Step S3011: Obtain the reference rate in the historical record, mark it as the historical rate, and at the same time obtain the corresponding T of the historical rate n , name it the historical range, and mark it as HT n ;

[0139] Step S3012: Each HT n contains different numbers of historical rates. Use HT n as the horizontal axis and the historical rate as the vertical axis to establish a plane rectangular coordinate system, name it the temperature-rate relationship graph, and input HT n and the corresponding historical rate into the temperature-rate relationship graph;

[0140] Step S3013: Conduct a quadratic polynomial regression analysis on the temperature-rate relationship graph, and name the regression function obtained as the temperature-rate relationship function;

[0141] Step S302: Predict the reference rate of the chemical pipeline based on the temperature-rate relationship function, and at the same time predict the remaining life of the chemical pipeline;

[0142] Step S302 includes the following sub-steps:

[0143] Step S3021: Obtain the T to which the working temperature of each day in the past year belongs, and at the same time record the duration during which the working temperature continuously stays within T n , mark it as R(S,n), where R(S,n) represents that the working temperature of the chemical pipeline has continuously stayed within T n for S days; n ;

[0144] Step S3022: Obtain the R(S,n) in the past year, and sort and number R(S,n) in chronological order, represented by the symbol K i , where i is a non-zero natural number and i is the serial number of K. Mark the S corresponding to K i as S i ;

[0145] Step S3023: Substitute the T i corresponding to K n into the temperature-rate relationship function, and mark the calculated reference rate as G i ;

[0146] Step S3024: Obtain the minimum limit value of the wall thickness of the chemical pipeline, name it the minimum thickness, set a constant m, with m initially being 1, and obtain the current weak thickness of the wall thickness, marked as F;

[0147] Step S3025: Calculate the predicted thickness through the formula , where L is the predicted thickness;

[0148] Step S3026: Compare the predicted thickness with the minimum thickness. If the predicted thickness is less than or equal to the minimum thickness, output a signal indicating the end of the lifespan; otherwise, output a signal for continued prediction.

[0149] Step S3027: If a signal for continued prediction is output, increment m by 1 and perform re - analysis until a signal indicating the end of the lifespan is output.

[0150] Step S3028: If a signal indicating the end of the lifespan is output, obtain the value of the current m, denoted as M, and calculate the sum of S when i is less than or equal to M, denoted as the remaining lifespan. i

[0151] Step S4: Monitor whether the change in the overall rate is abnormal. Step S4 includes the following sub - steps:

[0152] Step S401: Monitor the overall rate in real - time, denoted as the real - time rate. Obtain the overall rate of the previous evaluation period, denoted by the symbol C1 and marked as the previous rate, denoted by the symbol C2.

[0153] Step S402: Calculate C1 / C2, and mark the calculation result as the rate increase.

[0154] Step S403: Compare the rate increase with the first increase threshold. If the rate increase is less than the first increase threshold, output a signal indicating normal increase; otherwise, output a signal indicating abnormal increase.

[0155] Step S404: If a signal indicating abnormal increase is output, send a warning of pipeline abnormality.

[0156] Through the description of the above embodiments, the embodiments of the present invention can be provided as a method, a system, or a computer program product. Based on such an understanding, the above - mentioned technical solution, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product can be stored in a computer - readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0157] In the embodiments provided by the present invention, it should be understood that the disclosed system or method can be implemented in other ways. The embodiments described above are merely illustrative. For example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation. For another example, multiple modules or units can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some communication interfaces. The indirect coupling or communication connection of systems, modules, and units can be in electrical, mechanical, or other forms.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for online detection of corrosion in chemical pipelines, characterized in that: The steps include: Measure the wall thickness of chemical pipelines using ultrasonic phased array; Based on the wall thickness of different areas inside the chemical pipeline, the corrosion rate at the weakest part of the wall thickness is analyzed to obtain a reference rate, and the corrosion rate of the entire chemical pipeline is analyzed to obtain an overall rate, including the following sub-steps: based on the wall thickness of different areas inside the chemical pipeline, a thickness change distribution map is constructed and the corrosion rate at the weakest part of the wall thickness is analyzed in combination with the working temperature to obtain a reference rate; Based on the wall thickness of different areas inside the chemical pipeline, a thickness change distribution map is constructed and the corrosion rate at the weakest part of the wall thickness is analyzed in combination with the working temperature. The reference rate is obtained, which includes the following sub-steps: A plane rectangular coordinate system is established with the detection distance as the X-axis and the tube wall thickness as the Y-axis, named as the thickness change distribution diagram, and the tube wall thickness is entered into the thickness change distribution diagram according to the detection distance; The coordinate points in the thickness change distribution diagram are connected in the form of a smooth curve, and the connected curve is named a thickness change curve; Find the lowest point in the thickness variation curve, mark it as the weak point, and name the pipe wall thickness corresponding to the weak point as the weak thickness; Get the range of the working temperature of the chemical pipeline, name it as the temperature range, divide the temperature range into preset equal parts, and mark the different temperature ranges divided by the preset equal parts as T n , where n is a non-zero natural number and n is the serial number of T; For any T n , when the working temperature of the chemical pipeline is T n When the working temperature changes, and the working temperature is within T n When n changes, stop timing and maintain the recorded working temperature at T n The number of days in the range is named the evaluation period and is represented by the symbol t; After the timing stops, the operating temperature jumps to another T n , start timing again and record the next evaluation cycle; Each time the timing starts, record the weak thickness once, marked as H1, and each time the timing ends, record the weak thickness once, marked as H2, calculate H1-H2, and mark the calculation result as ΔH, named thickness difference; Calculate ΔH / t, mark the result as the reference rate, and record the T corresponding to the reference rate calculated this time. n ; Obtain historical reference rates, analyze the relationship between the change in reference rate and the operating temperature in combination with the operating temperature of the chemical pipeline, predict the reference rate, and then predict the remaining life of the chemical pipeline based on the prediction results; Monitor whether the overall rate changes are abnormal.

2. A chemical pipeline corrosion online detection method according to claim 1, characterized in that: The measurement of pipe wall thickness of chemical pipelines by ultrasonic phased array includes the following sub-steps: A detection starting point is selected on the chemical pipeline, and an ultrasonic sensor is installed on the chemical pipeline at a first interval starting from the detection starting point; Set the sampling frequency of the ultrasonic sensor to the standard frequency; The tube wall thickness obtained by the detection is counted, and the distance corresponding to the tube wall thickness is recorded and marked as the detection distance. The detection distance represents the length from the detection starting point, and the tube wall thickness represents the minimum value of the thickness within a circular area at the detection distance.

3. A chemical pipeline corrosion online detection method according to claim 2, characterized in that: Analyzing the overall corrosion rate of the chemical pipeline and obtaining the overall rate includes the following sub-steps: When the operating temperature is T n When the corrosion rate of the chemical pipeline is detected, the ER corrosion rate detection method is used to detect the corrosion rate of the entire chemical pipeline to obtain the detection rate; Calculate the average value of the detection rate in the corresponding evaluation period to get the overall rate.

4. A chemical pipeline corrosion online detection method according to claim 3, characterized in that: Obtain the historical reference rate, analyze the relationship between the change of the reference rate and the working temperature in combination with the working temperature of the chemical pipeline, predict the reference rate at the same time, and then predict the remaining life of the chemical pipeline based on the prediction results, including the following sub-steps: Analyze the temperature-rate relationship function based on historical reference rates and operating temperatures; The reference rate of the chemical pipeline is predicted based on the temperature-rate relationship function, and the remaining life of the chemical pipeline is also predicted.

5. A chemical pipeline corrosion online detection method according to claim 4, characterized in that: Analyzing the temperature-rate relationship function based on historical reference rates and operating temperatures includes the following sub-steps: Get the reference rate in the historical record, mark it as the historical rate, and get the T corresponding to the historical rate n , named as the historical range, marked as HT n ; Each HT n Contains different numbers of historical rates, in HT n As the horizontal axis, the historical rate as the vertical axis to establish a plane rectangular coordinate system, named the temperature rate relationship diagram, HT n And the corresponding historical rate is entered into the temperature rate relationship diagram; A quadratic polynomial regression analysis is performed on the temperature-rate relationship diagram, and the function obtained by regression is named the temperature-rate relationship function.

6. A chemical pipeline corrosion online detection method according to claim 5, characterized in that: Predicting the reference rate of a chemical pipeline based on the temperature-rate relationship function and predicting the remaining life of the chemical pipeline includes the following sub-steps: Get the T of the working temperature for each day in the past year n , while recording the operating temperature continuously at T n The duration of the period is marked as R(S,n), which means that the working temperature of the chemical pipeline is at T for S consecutive days. n Inside; Get R(S,n) in the past year, and sort and number R(S,n) in chronological order, using the symbol K i Indicates, where i is a non-zero natural number and i is the serial number of K, K i The corresponding S is marked as S i ; K i The corresponding T n Substitute into the temperature rate relationship function and mark the calculated reference rate as G i ; Get the minimum limit of the wall thickness of the chemical pipeline, named as minimum thickness, set a constant m, where m is initially 1, and get the current weak thickness of the wall thickness, marked as F; By formula Calculate the predicted thickness, where L is the predicted thickness; The predicted thickness is compared with the minimum thickness. If the predicted thickness is less than or equal to the minimum thickness, a life end signal is output, otherwise a continuous prediction signal is output; If the output continues to predict the signal, then m is increased by one and the analysis is repeated until the output is the life end signal; If the life-end signal is output, the current value of m is obtained, marked as M, and S is calculated when i is less than or equal to M. i The sum of is marked as the remaining life.

7. A chemical pipeline corrosion online detection method according to claim 6, characterized in that: Monitoring whether the overall rate change is abnormal includes the following sub-steps: Monitor the overall rate in real time, marked as the real-time rate, obtain the overall rate of the previous evaluation period, represented by symbol C1, and mark it as the previous rate, represented by symbol C2; Calculate C1 / C2 and mark the result as rate increase; The rate increase is compared with the first increase threshold. If the rate increase is less than the first increase threshold, a normal increase signal is output; otherwise, an abnormal increase signal is output; If the output increase signal is abnormal, a pipeline abnormality warning will be sent.

8. A chemical pipeline corrosion online detection system, used to implement a chemical pipeline corrosion online detection method according to any one of claims 1 to 7, characterized in that: It includes a thickness measurement module, a rate calculation module, a life prediction module and a rate monitoring module; the thickness measurement module, the rate calculation module and the rate monitoring module are respectively connected with the life prediction module data; The thickness measurement module is used to measure the wall thickness of the chemical pipeline by using an ultrasonic phased array; The rate calculation module is used to analyze the corrosion rate at the weakest part of the pipe wall thickness based on the pipe wall thickness of different areas inside the chemical pipeline to obtain a reference rate, and at the same time analyze the corrosion rate of the entire chemical pipeline to obtain an overall rate; The life prediction module is used to obtain the historical reference rate, analyze the relationship between the change of the reference rate and the working temperature in combination with the working temperature of the chemical pipeline, predict the reference rate, and then predict the remaining life of the chemical pipeline based on the prediction result; The rate monitoring module is used to monitor whether the change of the overall rate is abnormal.

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