CN214121502U

CN214121502U - Corrosion leakage detection system

Info

Publication number: CN214121502U
Application number: CN202021718238.5U
Authority: CN
Inventors: 刘航; 白添; 高桂; 张玉红; 王博; 王凯琳
Original assignee: Jilin Jianzhu University
Current assignee: Jilin Jianzhu University
Priority date: 2020-08-18
Filing date: 2020-08-18
Publication date: 2021-09-03
Anticipated expiration: 2030-08-18

Abstract

The invention belongs to detection and monitoring early warning of an industrial pipeline running state, and discloses a corrosion leakage detection system. The pipeline corrosion detection module, the pipeline leakage detection module, the A/D converter, the single chip microcomputer and the upper computer are connected in series; wherein: analog signals output by the pipeline corrosion detection module and the pipeline leakage detection module are connected into an A/D converter for analog-to-digital conversion, and digital signals obtained through the A/D converter are sequentially transmitted to the single chip microcomputer; the singlechip sequentially sends the two groups of signals to an upper computer through serial port communication; the corrosion and leakage states of the pipeline can be monitored in real time after the upper computer acquires data, and the acquired data are stored by the upper computer at intervals. The invention realizes the simultaneous detection of the corrosion and leakage deformation of the pipeline, and can feed back the running condition of the pipeline at any time and early warn. The prior art can not ensure the realization of high-precision detection under the condition of low cost, the system is simple, convenient and easy to maintain, and the target of high precision and low error can be realized under the condition of low manufacturing cost.

Description

Corrosion leakage detection system

Technical Field

The invention belongs to the detection and monitoring early warning of the operation state of an industrial pipeline, and particularly relates to a corrosion leakage detection system.

Background

In the field of pipeline leakage detection, the existing main detection technologies include a cable leak detection method, a detection ball method, an optical fiber leak detection method, a mass or volume balance method, a flow and pressure mutation method, a stress wave detection method, an acoustic emission leak detection method and the like. For the corrosion detection of pipes, the conventional main detection techniques include an on-site investigation method, an electrical resistance probe (ER) method, an electrochemical noise method, an ultrasonic method, a leakage flux detection method, a laser detection method, and the like. The existing pipeline corrosion and leakage detection is carried out separately, and the designed system can not simultaneously meet the requirements of real-time continuous high-precision detection, simple and convenient equipment, strong anti-interference capability, low manufacturing cost and the like.

Disclosure of Invention

The invention aims to provide a corrosion leakage detection system, which solves the problem that the corrosion and leakage conditions of a pipeline cannot be detected continuously and in real time at the same time. The problems of low system measurement precision, poor anti-interference performance, complex interface, higher cost and difficult maintenance are solved.

The present invention is achieved in such a way that,

a corrosion leak detection system, the system comprising: the pipeline corrosion detection module, the pipeline leakage detection module, the A/D converter, the single chip microcomputer and the upper computer are connected in series; wherein: the output ends of the pipeline corrosion detection module and the pipeline leakage detection module are connected into an A/D converter for analog-to-digital conversion, and are connected with a single chip microcomputer through the A/D converter; the singlechip is connected to the upper computer through a serial port.

Further, pipeline corrosion detection module includes power module, electrode matrix, data acquisition module and data processing circuit, the electrode matrix is FSM electrode matrix welding at the pipeline inner wall, applys the electric current at the pipeline inner wall through connecting power module, the collection end of data acquisition module passes through the probe and links to each other with the electrode of electrode matrix, utilizes the inner wall voltage that the voltage that data acquisition module gathered every electrode detected, and data acquisition module connects data processing circuit.

Further, the data acquisition module comprises a first pre-amplification circuit, a first filter circuit and a true effective value conversion circuit, the electrode matrix is connected with a detected electrode and is connected with the first pre-amplification circuit through an output end, the output end of the first pre-amplification circuit is connected with the filter circuit to filter noise components in signals as far as possible, finally, the filter circuit is connected with the true effective value conversion circuit, the first pre-amplification circuit adopts an amplifier INA118, and the true effective value conversion circuit adopts an AD736 true effective value converter chip.

Further, pipeline leakage detection module includes power module, strain bridge circuit, second preamplifier circuit and low pass filter circuit, and power module connects strain bridge circuit and provides excitation power for strain bridge circuit, and power module connects second preamplifier circuit and low pass filter circuit and provides 12V's voltage for second preamplifier circuit and low pass filter circuit, and strain bridge circuit is connected to second preamplifier circuit through the output, and second preamplifier circuit is connected to the low pass filter filtering through the output, and the low pass filter filtering leads to and connects to the host computer through the serial ports.

Further, the second preamplifier circuit uses the integrated operational amplifier AD620 as an operational amplifier chip, and a resistor of 499 Ω is connected across the pins No. 1 and No. 8 of the operational amplifier chip.

Further, the a/D converter employs a successive approximation type a/D converter PCF 8591.

Further, the single chip microcomputer is connected with the A/D converter through an IIC bus.

Compared with the prior art, the invention has the beneficial effects that: in the pipeline corrosion measuring part, the FSM measuring technology is mainly utilized, each electrode matrix is distributed in a pipeline to-be-measured area, the electrode matrix is used as a data output point, and a voltage signal generated after a current source flows in is output to a data acquisition circuit. After the data acquisition circuit performs pre-amplification and low-pass filtering on the input signal, the data processing circuit processes the signal and finally sends the signal to an upper computer after digital-to-analog conversion.

The invention realizes the simultaneous detection of the corrosion and leakage deformation of the pipeline, and can feed back the running condition of the pipeline at any time and early warn. The prior art can not ensure the realization of high-precision detection under the condition of low cost, the system is simple, convenient and easy to maintain, and the target of high precision and low error can be realized under the condition of low manufacturing cost.

Drawings

FIG. 1 is a general block diagram of a pipeline corrosion leak system;

FIG. 2 is a block diagram of a pipeline corrosion detection module;

FIG. 3 is a block diagram of a data acquisition module in the pipeline corrosion detection module;

FIG. 4 is a schematic diagram of a first pre-amplifier circuit in the pipeline corrosion detection module;

FIG. 5 is a schematic diagram of a first filter circuit in the pipeline corrosion detection module;

FIG. 6 is a true effective value conversion circuit in the pipeline corrosion detection module;

FIG. 7 is a block diagram of a pipeline leak detection module;

FIG. 8 is a strain bridge circuit diagram;

FIG. 9 is a circuit diagram of a pre-amplification of a deformation signal of a pipeline leakage;

FIG. 10 is a circuit diagram of a pipeline leakage distortion signal filter;

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to FIG. 1, a corrosion leak detection system, the system comprising: the pipeline corrosion detection module, the pipeline leakage detection module, the A/D converter, the single chip microcomputer and the upper computer are connected in series; wherein: analog signals output by the pipeline corrosion detection module and the pipeline leakage detection module are connected into an A/D converter for analog-to-digital conversion, and digital signals obtained through the A/D converter are sequentially transmitted to the single chip microcomputer; the singlechip sequentially sends the two groups of signals to an upper computer through serial port communication; the corrosion and leakage states of the pipeline can be monitored in real time after the upper computer acquires data, and the acquired data are stored by the upper computer at intervals.

Referring to fig. 2, the pipeline corrosion detection module mainly detects pipeline corrosion by using FSM technology. The pipeline corrosion detection technology is called as an electric field fingerprint method (FSM), and the pipeline corrosion detection technology is characterized in that the phenomena of corrosion, abrasion, cracks and the like easily occur in the pipeline in the transportation process, when the phenomena occur, the resistance of the pipeline changes, the current is introduced into a monitored metal pipeline, the change curve of the tiny voltage on the surface of the detected pipeline structure is analyzed by measuring the tiny potential difference formed on the surface of each detection area of the pipeline, and the pipeline corrosion can be detected. The pipeline corrosion detection module comprises a power supply module, an electrode matrix, a data acquisition module and a data processing circuit, wherein the electrode matrix is an FSM electrode matrix welded on the inner wall of the pipeline, current is applied to the inner wall of the pipeline through the power supply module, the acquisition end of the data acquisition module is connected with the electrode of the electrode matrix through a probe, the data acquisition module is used for acquiring the inner wall voltage of the voltage detection of each electrode, and the acquired current is processed through the data processing circuit.

Referring to fig. 3, the data acquisition module includes a first pre-amplifier circuit, a first filter circuit, and a true effective value conversion circuit, the electrode matrix sends the voltage signal of the electrode to be measured to the first pre-amplifier circuit, the first pre-amplifier circuit amplifies the signal to a certain magnitude, the filter circuit filters the noise component in the signal as much as possible, and finally, the true effective value conversion circuit processes the data to complete the data acquisition and processing task,

referring to fig. 4, the steel plate detected by the circuit is a metal material, and the resistance value between the detected probes is small. Therefore, the weak signals output by the electrode matrix are likely to be buried in noise and cannot be extracted. In order to obtain a useful signal, a device with high precision and high common mode rejection ratio is required to be selected to complete the signal processing. The application selects the amplifier INA118 for the high-precision instrument as a preamplification circuit chip. The INA118 is an instrumentation amplifier with low power consumption, high precision and high common mode rejection ratio, has very low offset voltage (50 muV) and very low noise (8nV/Hz), and is suitable for amplifying various weak signals. The amplification factor can be set by adjusting the resistance between the pins No. 1 and No. 8, the resistance adjustment equation is AV 1+50K omega/RG, the amplification factor range of INA118 is 1-1000, and the amplification factor of the circuit is set to 800 in order to accurately measure the voltage signal because the signal output by the electrode matrix is weak.

Referring to fig. 5, the first filter circuit: noise signals are inevitably mixed in the circuit amplification process, and the noise signals are amplified along with the amplifier. Therefore, a filter circuit must be designed so that the signal detected by normal pipe corrosion is maintained in the range of a few KHz. The signal is filtered using a low pass filter to filter out the noise signal therein to obtain a purer useful signal.

Referring to fig. 6, the true significance conversion circuit: the signal is filtered to become a useful signal with less noise, but the signal is an alternating current signal and the amplitude is still changing, which is inconvenient for direct measurement. Thus, the present circuit uses true significance measurements to process the signal. The method is to convert the effective value of the measured signal into the true root mean square value of the instantaneous value of the measured signal in proportion to complete the conversion of the true effective value. Theoretically the circuit is able to measure the true effective value of an arbitrary waveform. The circuit can accurately measure the effective value of the input waveform regardless of the amplitude, frequency or shape of the input waveform without considering the parameters and distortion of the measured signal. The true effective value conversion chip adopted by the circuit is an AD736 true effective value converter chip proposed by AD company in America.

Referring to fig. 7, the pressure at the leak in the pipe changes when the pipe leaks, and this change causes a change in the deformation of the pipe wall in the vicinity of the leak hole. Therefore, the deformation of the pipe wall can be used as a basic research object for detecting the leakage of the pipe. Whether the pipeline leaks or not can be judged by detecting the deformation change of the pipe wall. The pipeline leakage detection module comprises a power module, a strain bridge circuit, a second preamplification circuit and a low-pass filter circuit, wherein the power module provides an excitation power supply for the strain bridge circuit, the second preamplification circuit and the low-pass filter circuit provide +/-12V voltage, the strain bridge circuit serves as a signal conversion circuit and converts a tiny strain signal into a voltage signal and outputs the voltage signal to the second preamplification circuit, the second preamplification circuit amplifies the tiny voltage output by the strain bridge circuit, the output signal of the preamplification circuit is connected into the low-pass filter for filtering, and an analog signal output after filtering is transmitted to an upper computer through serial port communication after analog-to-digital conversion.

Referring to fig. 8, the voltage signal output by the strain bridge circuit is small, and there is a certain distance between the circuits, which causes voltage drop loss, so that it is inconvenient to directly measure the signal. The weak voltage signal output by the strain bridge circuit needs to be amplified by an operational amplifier and then analyzed and processed. In addition, the signal output by the strain bridge circuit is a differential mode signal, and the signal has sensor internal resistance in the transmission process, interference of wire resistance and external environment noise and interference of noise generated by the operational amplifier to an amplification result. Therefore, in order to ensure that the signal is not distorted and the interference of noise is reduced to the maximum possible extent, the operational amplifier should have: high gain, high common mode rejection ratio, high input impedance, low noise, and excellent dynamic characteristics.

Referring to fig. 9, the present embodiment selects an integrated operational amplifier AD620 for the operational amplifier chip of the pre-amplifier circuit. It is an operational amplifier for precision instruments introduced by ADI of America. The operational amplifier for the precision instrument, which is formed by three operational amplifiers, of the chip has the characteristic index which is much higher than that of the operational amplifier for the precision instrument, which is formed by three independent operational amplifiers, the input end of the operational amplifier has the overvoltage protection function, and the operational amplifier also has the advantages of low offset voltage, small temperature drift, high common mode rejection ratio and extremely high input impedance. The circuit can accurately amplify input signals by required times by externally connecting a resistor, and the circuit is bridged with a resistor of 499 omega between

pins

1 and 8 of the chip to accurately amplify signals output by the strain bridge by 100 times.

Referring to fig. 10, the low pass filter circuit: a circuit for passing a desired signal and suppressing an undesired signal. Filters are widely used in the fields of information processing, data transmission, interference suppression, and the like. The filters can be classified into digital filters, active filters and passive filters. The amplitude-frequency characteristic of the active filter is steep, and the circuit design is complex. The passive filtering has a simple structure, is easy to design and is generally used in a power circuit, but the amplitude-frequency characteristic of the passive filtering is not as good as that of an active filter due to the large volume. Digital filters are commonly used in applications where digital signals are processed. The active filter is adopted to filter signals, and the used active filter device is a high-precision operational amplifier OP07 which has the characteristics of low input offset voltage, low temperature drift, low input noise, high stability and the like. The filter and the resistor capacitor can form an active low-pass filter circuit.

The signal output by the strain bridge circuit has more noise and the operational amplifier chip is easily influenced by the power supply interference voltage. Therefore, the power supply voltage needs to be relatively stable, and the power supply selected by the invention is a high-precision multi-tap adjustable direct current voltage-stabilizing power supply with an output range of +/-15V for supplying power to the circuit.

The A/D converter adopted by the A/D converter is a successive comparison type A/D converter PCF8591, a single power supply (3.3V) power supply and a low-power consumption 8-bit CMOS digital-to-analog converter. With 4 analog inputs, 1 digital output and an IIC bus interface. PCF8591 has 3 address pins a0, a1, and a2 through which device addresses can be programmed, up to 8 PCF8591 devices can be externally connected on the IIC bus without additional hardware. The PCF8591 completes the processes of data processing, a/D converter configuration, and inter-device communication through the IIC bus interface.

The A/D converter adopts a successive approximation type A/D converter PCF8591, and the configuration of the A/D converter comprises: firstly, the single chip starts an IIC bus and sends an initial signal, then sends a reading address byte and a reading and writing bit, and the address of an A/D converter is 0; then the A/D converter sends out a response signal, and the singlechip receives the response signal and then sends out the slave address and the reading signal again; the slave machine responds again, the single chip microcomputer reads the data of the slave machine at the moment, the single chip microcomputer sends a response signal to the A/D converter when reading one byte, when the single chip microcomputer does not send the response signal, the data reading is finished, then the single chip microcomputer sends a stop signal to the A/D converter, and at the moment, the data transmission is finished.

The single chip microcomputer adopts an AT89C52 series single chip microcomputer produced by ATMEL company in America. The single chip microcomputer is a high-performance and low-voltage 8-bit microcontroller chip, the crystal oscillation frequency is 11.0592Mhz, and the single chip microcomputer contains a random data memory (RAM) with 256 bytes and a repeatable erasable program memory (ROM) with 8k bytes. The single chip microcomputer has 4 8-bit parallel I/O ports, 2 external interrupt interfaces, 3 programmable timing counter interfaces, 2 serial communication interfaces and 2 read-write ports. The single chip microcomputer has the characteristics of strong function, high integration level and reliability, low power consumption, small size, flexibility and the like, and is widely applied to the electronic industry.

The single chip microcomputer takes an AT89C52 single chip microcomputer as a core to complete the collection and processing work of corrosion detection circuit signals and leakage detection circuit signals, and sends the collected data to upper computer software according to a serial port communication protocol. The lower computer software work flow is as follows: after the system is powered on, an initialization process is started, wherein the initialization process comprises the initialization of an internal function register of the single chip microcomputer, the initialization of interruption, the initialization of a timer and the initialization of a serial port. After the initialization process is finished, the single chip microcomputer enters a main program stage, and then the single chip microcomputer sequentially executes tasks according to a designed sequence. And then, the single chip microcomputer is communicated with the A/D converter through the IIC bus, the A/D converter sequentially sends the data subjected to analog-to-digital conversion to the single chip microcomputer, and the single chip microcomputer processes the acquired signals through a serial port and then sends the processed signals to an upper computer.

Compared with the prior art, the system provided by the invention realizes simultaneous detection of corrosion and leakage deformation of the pipeline, and can feed back the running condition of the pipeline at any time and early warn. The prior art can not ensure the realization of high-precision detection under the condition of low cost, the system is simple, convenient and easy to maintain, and the target of high precision and low error can be realized under the condition of low manufacturing cost. The experimental data are shown in table 1.

Table 1 pipeline leak verification data

The error between the voltage measured by the upper computer and the voltage measured by the experiment is small. And along with the change of deformation, the data that the host computer gathered also can corresponding change, and the system will produce alarm signal when the variable quantity of deformation has surpassed the alarm value of design.

Pipeline corrosion verification data

Table 4-2Pipeline corrsion verification data

The table shows that the deeper the defect depth in the electrode matrix, the higher the voltage signal acquired by the upper computer, and the smaller the error of the experimental data acquired by the upper computer compared with the experimental result.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A corrosion leak detection system, comprising: the pipeline corrosion detection module, the pipeline leakage detection module, the A/D converter, the single chip microcomputer and the upper computer are connected in series; wherein: the output ends of the pipeline corrosion detection module and the pipeline leakage detection module are connected into an A/D converter for analog-to-digital conversion, and are connected with a single chip microcomputer through the A/D converter; the singlechip is connected to the upper computer through a serial port.

2. The system of claim 1, wherein the pipeline corrosion detection module comprises a power supply module, an electrode matrix, a data acquisition module and a data processing circuit, the electrode matrix is an FSM electrode matrix welded on the inner wall of the pipeline, current is applied to the inner wall of the pipeline by connecting the power supply module, the acquisition end of the data acquisition module is connected with the electrodes of the electrode matrix through probes, the data acquisition module is used for acquiring the inner wall voltage detected by the voltage of each electrode, and the data acquisition module is connected with the data processing circuit.

3. The system of claim 2, wherein the data acquisition module comprises a first pre-amplifier circuit, a first filter circuit, and a true-significance converter circuit, the electrode matrix is connected to the electrode to be measured and connected to the first pre-amplifier circuit through an output terminal, the output terminal of the first pre-amplifier circuit is connected to the filter circuit to filter out noise components in the signal as much as possible, and finally, the filter circuit is connected to the true-significance converter circuit, the first pre-amplifier circuit employs an amplifier INA118, and the true-significance converter circuit employs an AD736 true-significance converter chip.

4. The system of claim 1, wherein the pipeline leakage detection module comprises a power module, a strain bridge circuit, a second preamplifier circuit and a low-pass filter circuit, the power module is connected with the strain bridge circuit to provide excitation power for the strain bridge circuit, the power module is connected with the second preamplifier circuit and the low-pass filter circuit to provide +/-12V voltage for the second preamplifier circuit and the low-pass filter circuit, the strain bridge circuit is connected to the second preamplifier circuit through an output end, the second preamplifier circuit is connected to the low-pass filter through an output end for filtering, and the low-pass filter is connected to an upper computer through a serial port.

5. The system of claim 4, wherein the second pre-amplifier circuit uses an integrated operational amplifier AD620 as an operational amplifier chip, and a 499 Ω resistor is connected across pins No. 1 and No. 8 of the operational amplifier chip.

6. The system of claim 4, wherein said a/D converter is a successive approximation a/D converter PCF 8591.

7. The system of claim 1, wherein the single chip is coupled to the a/D converter via an IIC bus.