CN210294141U - Metal pipeline corrosion monitoring system - Google Patents
Metal pipeline corrosion monitoring system Download PDFInfo
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- CN210294141U CN210294141U CN201920906165.3U CN201920906165U CN210294141U CN 210294141 U CN210294141 U CN 210294141U CN 201920906165 U CN201920906165 U CN 201920906165U CN 210294141 U CN210294141 U CN 210294141U
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Abstract
The utility model discloses a metal pipeline corrosion monitoring system, include: the forward excitation current source is used for inputting forward excitation current to two ends of a region to be monitored of the pipeline; a resistive network welded to an area to be monitored; the reference plate is provided with reference electrodes at two ends of the reference resistor; the differential pressure signal monitoring unit is used for measuring to obtain a differential pressure signal between any two monitoring electrodes; the first amplifying circuit is connected to the differential pressure signal monitoring unit; the second amplifying circuit is connected to the first amplifying circuit; a phase shift circuit connected to the second amplification circuit; a phase-locked amplifying circuit connected to the phase-shifting circuit; the digital-to-analog conversion circuit is connected to the phase-locked amplifying circuit and is used for converting the analog signal output by the phase-locked amplifying circuit into a digital signal; and the main control circuit samples the digital signals according to a set time interval and stores the sampling result.
Description
Technical Field
The utility model relates to a measure technical field, particularly, relate to a metal pipeline corrosion monitoring system.
Background
The existing metal pipeline corrosion monitoring method by using an electric field texture characteristic method adopts a direct current constant current source for excitation to obtain a potential matrix of a measured pipeline, and the corrosion trend of the pipeline is known by monitoring the potential change condition of each electrode. This method must use a constant current of up to tens or even hundreds of amperes to obtain a measurable voltage amplitude, and a relatively high signal-to-noise ratio. The large excitation current not only causes large electric energy consumption, the related electronic components generate heat seriously, a thicker cable needs to be provided, but also poses a threat to flammable and explosive environments. In addition, the monitoring accuracy of the method is also easily influenced by factors such as environmental temperature change, electrode contact resistance, environmental electromagnetic interference and the like.
SUMMERY OF THE UTILITY MODEL
The utility model provides a metal pipeline corrosion monitoring method and system, which are used for overcoming at least one problem existing in the prior art.
The embodiment of the utility model provides a metal pipeline corrosion detection system, include: the forward excitation current source is used for inputting forward excitation current to two ends of the to-be-detected region of the pipeline; the resistor network is welded to the area to be detected; the resistor network comprises N × M resistors with the same size; wherein every M resistors are connected in series; n is a positive integer greater than or equal to 1, and M is a positive integer greater than 1; the distance between the adjacent resistors is a fixed distance; along the current flowing direction, two ends of each resistor are provided with detection electrodes; the control board is a metal plate made of the same material as the pipeline, one end of the control board is electrically connected with the pipeline, a reference resistor is arranged on the control board, and reference electrodes are arranged at two ends of the reference resistor; the differential pressure signal detection unit is used for measuring and obtaining differential pressure signals between any two detection electrodes; a first amplification circuit which is a differential amplification circuit; is connected to the differential pressure signal detection unit; a second amplification circuit that is a chopper-based amplification circuit; is connected to the first amplifying circuit; a phase shift circuit connected to the second amplification circuit for adjusting the phase of the signal output from the second amplification circuit to the same phase as the reference signal; the phase-locked amplifying circuit is connected to the phase-shifting circuit and is used for amplifying the signal with the same frequency as the reference signal; the digital-to-analog conversion circuit is connected to the phase-locked amplifying circuit and is used for converting the analog signal output by the phase-locked amplifying circuit into a digital signal; and the main control circuit is used for sampling the digital signals according to a set time interval and storing the sampling result.
Optionally, the forward excitation current is a forward excitation current with adjustable frequency from 1Hz to 1 kHz.
Optionally, the fixed distance is 2-3 times the thickness of the wall of the conduit.
Optionally, the two monitoring electrodes are respectively located on two sides of the weld on the pipeline.
The utility model discloses innovation point includes:
1. compared with the electric field texture characteristic method based on the constant-current direct-current source, the utility model adopts the alternating-current excitation current source and the phase-locked amplification technology, so that the required excitation current is 1 to 2 orders of magnitude smaller, and better signal-to-noise ratio can be provided, the requirement on electronic elements is lower, and the safety is better; meanwhile, the change condition of the resistance network of the sensitive area of the detected pipeline can be measured, and an accurate data basis is provided for understanding and mastering the development trend of the corrosion of the pipeline; this is one of the innovative points of the embodiments of the present invention.
2. The utility model discloses a 1Hz is applied to the pipeline and is surveyed the region to 1kHz adjustable sine AC excitation current source, and through sampling, signal amplification, filtering, lock-in amplification and digital-analog conversion to the electrode matrix of being surveyed the region, can directly obtain and respectively surveyed the resistance between the electrode pair, through the monitoring to resistance network, obtain the current situation that reflects the pipeline corrosion and the accurate data of development trend, this is the utility model discloses one of the innovation point of embodiment.
3. The utility model adopts the phase-locked amplification technology, which can reduce the peak-peak value of the sine excitation current source to below 1 ampere until the level of 0.1 ampere; the excitation current source reduce by a wide margin not only practices thrift the electric energy, has reduced the requirement to electronic component, has improved the security under the inflammable and explosive environment moreover, and this is one of the innovation point of the embodiment of the utility model.
4. The phase-locked amplification technique is because only enlargies the measured signal with reference signal syntonic frequency, consequently can eliminate the influence of factors such as ambient temperature, electrode contact resistance, environment electromagnetic interference, obtains the higher SNR than direct current constant current excitation source, and this is one of the innovation point of the embodiment of the utility model.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a metal pipeline corrosion monitoring system according to an embodiment of the present invention;
fig. 2a is a side view of current injection in an embodiment of the present invention;
fig. 2b is a top view of current injection in an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating calculation of the distance between the electrode m and the electrode n according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a connection relationship between the resistor network, the comparison board and the pipeline according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without any creative effort belong to the protection scope of the present invention.
It should be noted that the terms "comprises" and "comprising" and any variations thereof in the embodiments and drawings of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
The embodiment of the utility model discloses metal pipeline corrosion monitoring method and system, the following detailed description.
Fig. 1 is a schematic structural diagram of a metal pipeline corrosion monitoring system according to an embodiment of the present invention.
In fig. 1, the metal pipeline corrosion monitoring system mainly includes a sinusoidal excitation current source, a resistor network, a signal preprocessing module (including a first amplifying circuit, a second amplifying circuit, and a phase-shifting circuit), a phase-locked amplifying module (including a phase-locked amplifying circuit and a sampling circuit), a main control circuit, and data processing and analyzing software (including a calculating unit and a determining unit).
The sinusoidal excitation current source generates a sinusoidal waveform current which is injected into the monitored region of the pipeline. The resistors between the electrode pairs of the monitored area form a resistor network to convert the current signal into a voltage signal. Since the voltage signal is weak, usually in the nV level, it needs to be pre-amplified by the preprocessing circuit to a level (above 0.1V) enough to drive the phase-locked amplifier circuit. The amplified signal enters a phase-locked amplifying circuit and is operated with a reference signal. The output of the phase-locked amplifying circuit is a direct current signal. The phase of the signal to be measured is adjusted to be the same as that of the reference signal, and the amplitude of the direct current signal output by the phase-locked amplifying circuit is only related to the amplitude of the signal to be measured. Phase-locked amplification can therefore remove interference at all different frequencies, including dc components and ambient electromagnetic interference.
Specifically, the resistance network is welded to the area to be detected; the resistor network comprises N × M resistors with the same size; wherein every M resistors are connected in series; n is a positive integer greater than or equal to 1, and M is a positive integer greater than 1; the distance between adjacent resistors is a fixed distance. For example, M is 5 and N is 4.
Monitoring electrodes are arranged at two ends of each resistor along the current flowing direction.
Specifically, the comparison board is a metal plate made of the same material as the pipeline, one end of the comparison board is electrically connected with the pipeline, a reference resistor is arranged on the comparison board, and reference electrodes are arranged at two ends of the reference resistor.
The differential pressure signal monitoring unit measures and obtains a differential pressure signal between any two detection electrodes. The preprocessing circuit comprises a first amplifying circuit, a second amplifying circuit and a phase-shifting circuit. The first amplifying circuit is a high-precision differential amplifying circuit; is connected to a differential pressure signal monitoring unit; the second amplifying circuit is a chopping-based low-noise and low-drift amplifying circuit; is connected to the first amplifying circuit; and the phase shifting circuit is connected to the second amplifying circuit and is used for adjusting the phase of the signal output by the second amplifying circuit to be the same as the phase of the reference signal.
The phase-locked amplifying circuit is connected to the phase-shifting circuit and is used for amplifying the signal with the same frequency as the reference signal; and the digital-to-analog conversion circuit is connected to the phase-locked amplifying circuit and is used for converting the analog signal output by the phase-locked amplifying circuit into a digital signal.
The main control circuit is used for sampling the digital signals according to a set time interval and storing sampling results; and the calculation unit is used for calculating and obtaining a texture characteristic coefficient FC of the pipeline between the electrode pair formed by the two detection electrodes according to the sampling result:
therein, FCki(t) -electrode pair kiTexture feature coefficients at time t; v. ofki(0) -electrode pair kiVoltage at the monitoring start t ═ 0; v. ofk0(0) -reference electrode pair k0Voltage at the monitoring start t ═ 0; v. ofki(t) -electrode pair kiVoltage at time t; v. ofk0(t) -reference electrode pair k0Voltage at time t; and the determining unit is used for determining the corrosion degree of the metal pipeline according to the texture characteristic coefficient FC.
Optionally, the forward excitation current is a forward excitation current with adjustable frequency from 1Hz to 1 kHz.
Optionally, the fixed distance is 2-3 times the thickness of the wall of the conduit.
The voltage f between two points can be expressed as a function f (l) of the distance l, as can be seen with reference to fig. 2a and 2b, with the following correspondence:
wherein, K0(. X) is a modified Bessel function of the second type, T is the pipe wall thickness, k2I ω μ σ, ω being frequency, μ being permeability, σ being material conductivity;
wherein I is the amplitude of the input forward excitation current,
the distance between the electrode point m and the electrode point n is shown, and the calculation principle is adoptedAs shown in fig. 3.
The welding seam is generally a place where corrosion is easy to occur, and important monitoring is needed; two monitoring electrodes may be respectively provided to both sides of a weld on the pipe.
Fig. 4 is a schematic diagram illustrating a connection relationship between the resistor network, the control board and the pipeline according to an embodiment of the present invention. As shown in fig. 4, the sinusoidal current is injected at the current input terminal 1 and returns at the current feed terminal 7. The arrow direction in the figure is the current path. Since the excitation current is sinusoidal, the current is in fact bidirectional. And 5, a comparison plate, which is made of the same material as the pipeline and is thermally coupled with the pipeline, wherein one side of the comparison plate is electrically connected with the pipeline, so that current flows through the pipeline and the comparison plate in sequence. 2 is a detection electrode, 3 is a resistance network indication, usually the probe electrodes are arranged at two sides of the welding seam 4, and the electrodes are arranged in rows and columns at equal intervals; the spacing is selected to be 2-3 times the wall thickness of the pipeline. Reference resistance 6 is the resistance between the two electrodes on the control plate. The comparison board and the reference resistor are used for correcting the influence of factors such as temperature, humidity, excitation current amplitude change and the like on the detection result.
Compared with the electric field texture characteristic method based on the constant-current direct-current source, the utility model adopts the alternating-current excitation current source and the phase-locked amplification technology, so that the required excitation current is 1 to 2 orders of magnitude smaller, and better signal-to-noise ratio can be provided, the requirement on electronic elements is lower, and the safety is better; meanwhile, the change condition of the resistance network of the sensitive area of the detected pipeline can be measured, and the purpose of knowing and mastering the development trend of the corrosion of the pipeline is achieved.
The utility model discloses a 1Hz is applied to the pipeline and is surveyed the region to 1kHz adjustable sine AC excitation current source, and through sampling, signal amplification, filtering, lock-in amplification and digital-analog conversion to the electrode matrix of being surveyed the region, can directly obtain and respectively surveyed the resistance between the electrode pair, through the analysis to resistance network, judge the current situation and the development trend of pipeline corrosion.
The utility model adopts the phase-locked amplification technology, which can reduce the peak-peak value of the sine excitation current source to below 1 ampere until the level of 0.1 ampere; the excitation current source is greatly reduced, so that electric energy is saved, the requirement on electronic elements is lowered, and the safety in the flammable and explosive environment is improved.
The phase-locked amplification technology only amplifies the measured signal with the same frequency as the reference signal, so that the influence of factors such as ambient temperature, electrode contact resistance, ambient electromagnetic interference and the like can be eliminated, and a signal-to-noise ratio higher than that of a direct-current constant-current excitation source is obtained.
The embodiment of the utility model also discloses a metal pipeline corrosion detection method based on above-mentioned system, include:
inputting forward excitation current into two ends of a region to be detected, wherein a resistance network and a comparison plate are welded in the region to be detected; the resistor network comprises N × M resistors with the same size; wherein every M resistors are connected in series; n is a positive integer greater than or equal to 1, and M is a positive integer greater than 1; along the current flowing direction, two ends of each resistor are provided with detection electrodes; the distance between the adjacent resistors is a fixed distance; the comparison board is connected with the resistance network comparison board and is a metal board made of the same material as the pipeline, one end of the comparison board is electrically connected with the pipeline, a reference resistor is arranged on the comparison board, and reference electrodes are arranged at two ends of the reference resistor; measuring to obtain a differential pressure signal between any two detection electrodes, and inputting each differential pressure signal and a reference signal between the reference electrodes into a first amplifying circuit, a second amplifying circuit, a phase-shifting circuit, a phase-locked amplifying circuit, a digital-to-analog conversion circuit and a main control circuit; the first amplifying circuit is a high-precision differential amplifying circuit, and the second amplifying circuit is a chopping-based low-noise and low-drift amplifying circuit; the phase shift circuit is used for adjusting the phase of the signal output by the second amplifying circuit to be the same as the phase of the reference signal; the phase-locked amplifying circuit is used for amplifying a signal with the same frequency as the reference signal; the digital-to-analog conversion circuit is used for converting the analog signal output by the phase-locked amplifying circuit into a digital signal; the main control circuit is used for sampling the digital signal according to a set time interval and storing a sampling result; according to the sampling result, calculating to obtain a texture characteristic coefficient FC of the pipeline between the electrode pair formed by any two detection electrodes:
therein, FCki(t) -electrode pair kiTexture feature coefficients at time t; v. ofki(0) -electrode pair kiVoltage at the monitoring start t ═ 0; v. ofk0(0) -reference electrode pair k0Voltage at the monitoring start t ═ 0; v. ofki(t) -electrode pair kiVoltage at time t; v. ofk0(t) -reference electrode pair k0Voltage at time t; and determining the corrosion degree of the metal pipeline according to the texture characteristic coefficient FC.
Optionally, the forward excitation current is a forward excitation current with adjustable frequency from 1Hz to 1 kHz.
Optionally, the fixed distance is 2-3 times the thickness of the wall of the conduit.
Optionally, the method for detecting corrosion of a metal pipeline further includes: for the electrodes irregularly distributed on the outer surface of the pipeline, the corresponding relation between the voltage and the wall thickness is obtained by the following formula:
wherein, K0(. X) is a modified Bessel function of the second type, T is the pipe wall thickness, k2I ω μ σ, ω being frequency, μ being permeability, σ being material conductivity;
wherein I is the amplitude of the input forward excitation current,
representing the distance between point m and point n.
Optionally, the two detection electrodes are respectively located on two sides of the weld on the pipeline.
Compared with the electric field texture characteristic method based on the constant-current direct-current source, the utility model adopts the alternating-current excitation current source and the phase-locked amplification technology, so that the required excitation current is 1 to 2 orders of magnitude smaller, and better signal-to-noise ratio can be provided, the requirement on electronic elements is lower, and the safety is better; meanwhile, the change condition of the resistance network of the sensitive area of the detected pipeline can be measured, and the purpose of knowing and mastering the development trend of the corrosion of the pipeline is achieved.
The utility model discloses a 1Hz is applied to the pipeline and is surveyed the region to 1kHz adjustable sine AC excitation current source, and through sampling, signal amplification, filtering, lock-in amplification and digital-analog conversion to the electrode matrix of being surveyed the region, can directly obtain and respectively surveyed the resistance between the electrode pair, through the analysis to resistance network, judge the current situation and the development trend of pipeline corrosion.
The utility model adopts the phase-locked amplification technology, which can reduce the peak-peak value of the sine excitation current source to below 1 ampere until the level of 0.1 ampere; the excitation current source is greatly reduced, so that electric energy is saved, the requirement on electronic elements is lowered, and the safety in the flammable and explosive environment is improved.
The phase-locked amplification technology only amplifies the measured signal with the same frequency as the reference signal, so that the influence of factors such as ambient temperature, electrode contact resistance, ambient electromagnetic interference and the like can be eliminated, and a signal-to-noise ratio higher than that of a direct-current constant-current excitation source is obtained.
The following provides a specific example to illustrate the method of the present invention.
Sinusoidal excitation current source: the current amplitude is continuously adjustable by generating a sine excitation current source with stable amplitude and Automatic Gain Control (AGC).
A sinusoidal excitation current source is injected into both ends of the monitored region of the pipe. Welding the electrode matrix in the monitored area. A voltage difference will occur between two adjacent electrodes along the direction of current flow due to the presence of resistance.
The differential pressure signals between all the electrodes are gated through an analog switch, enter a high-precision differential amplification circuit and a low-noise low-drift amplification circuit and are subjected to pre-amplification. The nV signal between the electrodes is amplified to 0.1V or more to drive the subsequent phase-locked amplifier circuit.
The phase shift circuit adjusts the phase of the signal under test to be the same as the phase of the reference signal.
The phase-locked amplifying circuit amplifies the detected signal with the same frequency as the reference signal, and filters out interference, noise and direct-current components with different frequencies.
A digital-analog conversion sampling circuit with 16-bit precision is adopted to convert an analog signal into a digital signal.
The main control circuit samples according to a set time interval and stores a sampled digital result in a storage medium.
The main control circuit sends the real-time sampling result or the historical sampling result to a remote computer through the Ethernet, and data processing and analyzing software installed on the computer performs data display and result analysis.
The data processing and analyzing software on the computer can display and analyze the sampling result in a two-dimensional or three-dimensional graph mode and judge the corrosion condition of the pipeline.
Those of ordinary skill in the art will understand that: the figures are schematic representations of one embodiment, and the blocks or processes in the figures are not necessarily required to practice the present invention.
Those of ordinary skill in the art will understand that: modules in the devices in the embodiments may be distributed in the devices in the embodiments according to the description of the embodiments, or may be located in one or more devices different from the embodiments with corresponding changes. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention.
Claims (4)
1. A metal pipeline corrosion monitoring system, comprising:
the forward excitation current source is used for inputting forward excitation current to two ends of a region to be monitored of the pipeline;
a resistive network welded to an area to be monitored; the resistor network comprises N M resistors with the same size; wherein every M resistors are connected in series; n is a positive integer greater than or equal to 1, and M is a positive integer greater than 1; the distance between the adjacent resistors is a fixed distance; monitoring electrodes are arranged at two ends of each resistor along the current flowing direction;
the comparison plate is a metal plate made of the same material as the pipeline, one end of the comparison plate is electrically connected with the pipeline, a reference resistor is arranged on the comparison plate, and reference electrodes are arranged at two ends of the reference resistor;
the differential pressure signal monitoring unit is used for measuring and obtaining a differential pressure signal between any two monitoring electrodes;
a first amplification circuit that is a differential amplification circuit; the pressure difference signal monitoring unit is connected to the pressure difference signal monitoring unit;
a second amplification circuit that is a chopper-based amplification circuit; is connected to the first amplifying circuit;
the phase shift circuit is connected to the second amplifying circuit and is used for adjusting the phase of the signal output by the second amplifying circuit to be the same as the phase of the reference signal;
the phase-locked amplifying circuit is connected to the phase-shifting circuit and is used for amplifying a signal with the same frequency as the reference signal;
the digital-to-analog conversion circuit is connected to the phase-locked amplifying circuit and is used for converting the analog signal output by the phase-locked amplifying circuit into a digital signal;
and the main control circuit is used for sampling the digital signal according to a set time interval and storing a sampling result.
2. The metal pipeline corrosion monitoring system of claim 1, wherein the forward excitation current is a forward excitation current with a frequency adjustable from 1Hz to 1 kHz.
3. The metal pipe corrosion monitoring system of claim 1, wherein said fixed distance is 2 times the thickness of the pipe wall.
4. The metal pipe corrosion monitoring system of claim 1, wherein said two monitoring electrodes are located on both sides of a weld on said pipe.
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| CN201920906165.3U CN210294141U (en) | 2019-06-14 | 2019-06-14 | Metal pipeline corrosion monitoring system |
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| CN201920906165.3U CN210294141U (en) | 2019-06-14 | 2019-06-14 | Metal pipeline corrosion monitoring system |
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