Digital flowing current measuring device

Abstract

The invention relates to a digital flowing current measuring device which comprises a flowing current detector and a digital transmitter. The flowing current detector is used for collecting weak alternating current generated when sampling water is sheared, and the digital transmitter is used for processing the weak alternating current, judging the positive and negative polarities of the detected water and displaying and outputting the weak alternating current; the flowing current detector is provided with an irradiation-resistant part, electromagnetic compatibility and self-zero setting; and the digital transmitter is also provided with an irradiation-resistant part. The invention further comprises a working method of the digital flowing current measuring device. The beneficial effect of the invention is that a high-reliability solution is provided for monitoring the flowing current in a high-irradiation and strong-electromagnetic-interference scene. The device is suitable for wastewater treatment in the nuclear industry field, engine vibration monitoring and aircraft structure health monitoring in the environment field, reactor vibration monitoring and pipeline vibration monitoring in the petrochemical industry field, high-voltage transmission line vibration monitoring, wind driven generator vibration monitoring and other scenes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of analytical instruments for industrial process detection, and particularly relates to a digital online measurement device for flow current in liquid medium. BACKGROUND

[0002] Flow current detection technology, as a core means for characterizing the colloidal charge state in liquid, is widely used in water treatment flocculant dosing control, oil pipeline corrosion monitoring, papermaking and chemical industries or processes. However, the existing technology has the following defects:

[0003] Signal processing bottleneck: in the existing technology, analog amplification circuit is generally used to process the pA-level micro-current signal of the electrode, the circuit gain is large, and the existing flow current detection device has weak anti-electromagnetic interference ability (in industrial scenes such as frequency converter and high-power motor, 50 / 60Hz power frequency interference leads to deterioration of signal-to-noise ratio (measured noise is greater than or equal to ±0.5mV, which accounts for more than 30% of the effective signal)), resulting in significant zero drift, which needs to be manually adjusted frequently;

[0004] Functional limitation: only dimensionless analog current value can be output, data storage, remote communication and polarity intelligent judgment cannot be realized, and it is difficult to support intelligent operation and maintenance;

[0005] Poor environmental adaptability: traditional materials cannot withstand high radiation environments such as nuclear power plants, and the probe insulation layer is easily affected by electromagnetic interference, resulting in a sharp drop in sensitivity in low conductivity medium;

[0006] Dynamic response lag: long response time, unable to track water quality changes in real time, resulting in insufficient dosing control accuracy.

[0007] Therefore, it is particularly important to design a digital flow current measurement device that can withstand strong radiation, has strong electromagnetic compatibility, does not need to be adjusted repeatedly, can realize digital output and storage of measurement data, and can be intelligently operated and maintained. SUMMARY

[0008] The purpose of the present application is to overcome the deficiencies in the prior art, provide a digital flow current measurement device for digital online measurement of flow current in liquid medium (such as liquid medium in water treatment, petroleum chemical industry and other industries), and can characterize the colloidal charge state in liquid.

[0009] The digital flow current measurement device comprises a flow current detector and a digital transmitter; the flow current detector is electrically connected to the digital transmitter; the flow current detector is used to collect the weak alternating current generated when the sampled water is sheared, and the digital transmitter is used to process the weak alternating current, determine the positive and negative polarity of the measured water quality, and display and output; the flow current detector has a radiation-resistant part, electromagnetic compatibility and self-zeroing; the digital transmitter also has a radiation-resistant part.

[0010] As a preference:

[0011] The flow current detector includes a detection chamber, a plunger, a probe, an electrode, a drive device, a stall protection and a speed control device; a sampling water inlet and a sampling water outlet are provided on the detection chamber, and the detection chamber is used to hold sampling water. The sampling water flows into the detection chamber from the sampling water inlet, passes through the space between the plunger and the detection chamber, and flows out of the detection chamber from the sampling water outlet; a plunger is provided above the detection chamber, the plunger is connected to the drive device, and the drive device is electrically connected to the stall protection and speed control device; a probe is provided in the detection chamber, the probe is electrically connected to the electrode, the electrode is electrically connected to a digital transmitter for collecting motor speed signals, and the digital transmitter is electrically connected to a photoelectric switch; the digital transmitter includes a power supply module, an analog signal acquisition module, a digital signal acquisition module, a central processing unit, a display device and a constant current power supply, the external power supply is electrically connected to the power supply module, the power supply module is electrically connected to the drive device, the analog signal acquisition module, the digital signal acquisition module and the central processing unit; the analog signal acquisition module is electrically connected to the digital signal acquisition module, the digital signal acquisition module is electrically connected to the central processing unit, and the central processing unit is electrically connected to the display device and the constant current power supply; the display device is a resistive touch screen, which takes into account both intelligence and radiation resistance;

[0012] The driving device is used to drive the plunger to move up and down in the detection chamber, driving the sampled water to perform piston movement. The piston movement of the sampled water is used to generate a weak AC current with a frequency of 4Hz on the electrode. The frequency of the AC current is the speed frequency of the driving device. The stall protection and speed control device is used to perform stall protection and speed control on the driving device. The driving device is adaptive to fixed frequency control.

[0013] The electrodes are used to send weak AC current analog signals to the analog signal acquisition module in the digital transmitter; the power supply module is used to supply power to the electrical equipment, and the power supply module is provided with an overcurrent protection circuit; the digital signal acquisition module is used to convert the weak AC current analog signal into a digital signal and send the digital signal to the central processing unit; the central processing unit is used to perform logical operations on the digital signal, send the data to be displayed to the display device, and send instructions to the constant current power supply to control its output voltage range; the display device is used to display the data to be displayed;

[0014] The insulation layer of the probe is made of radiation-resistant materials such as polyimide (PI) or polyetheretherketone (PEEK). The insulation layer of the cables between the electrical devices is also made of radiation-resistant materials such as polyimide (PI) or polyetheretherketone (PEEK), thereby improving the radiation resistance of the cables.

[0015] As a preference:

[0016] The analog signal acquisition module comprises a high-precision weak current detection module and a high-resolution analog-digital converter; the high-precision weak current detection module is electrically connected with the electrode in the flow current probe, and the high-precision weak current detection module is also electrically connected with the high-resolution analog-digital converter, and the high-resolution analog-digital converter is electrically connected with the central processing unit;

[0017] an electrode for sensing a weak alternating current generated by the piston movement of the sampling water on the electrode and converting the weak alternating current into a micro-current signal, and sending the micro-current signal to the high-precision weak current detection module;

[0018] a high-precision weak current detection module for amplifying and conditioning the micro-current signal, and sending the amplified and conditioned micro-current signal to the high-resolution analog-digital converter;

[0019] a high-resolution analog-digital converter for digitizing the amplified and conditioned micro-current signal, and sending the digitized micro-current signal to the central processing unit, and the digitizing precision is not less than 24 bits;

[0020] a central processing unit for processing the digitized micro-current signal, determining the positive and negative polarity of the measured water quality in real time, and displaying and outputting;

[0021] The flow current probe is also provided with a solenoid valve, and the solenoid valve is used for timing flushing of the probe.

[0022] As preferred:

[0023] a digital communication interface module is further provided, the central processing unit is electrically connected with the digital communication interface module, and the digital communication interface module is electrically connected with the display device;

[0024] the digital communication interface module is used for sending to-be-displayed data to the display device, and the to-be-displayed data comprises a flow current value and equipment state information.

[0025] As preferred, the digital communication interface module supports at least one of the following industrial standard protocols: a Modbus protocol configured on an RS485 interface, a HART protocol configured for a 4-20 mA analog signal, a TCP or IP protocol configured for an Ethernet, and a wireless protocol configured for a wireless communication module; wherein the wireless protocol is a LoRa protocol, a WiFi protocol or a Bluetooth protocol; and the analog signal acquisition module is a pA-level analog signal acquisition module.

[0026] As preferred:

[0027] The probe is a silver material electrode (diameter 8 mm, thickness 0.5 mm), and the silver material electrode surface is formed with an Ag / AgCl active layer through electrochemical oxidation treatment, which can realize 3 times ion exchange efficiency improvement (compared with traditional graphite electrode); still maintains 1 pA detection sensitivity in low conductivity medium (<10 muS / cm); the electrode is in the shape of inverted Chinese character 'yi' along the two side walls and the bottom of the detection chamber, and an insulating layer with a thickness of 3 mm made of polytetrafluoroethylene is arranged in the probe to prevent current leakage.

[0028] As preferred: the driving device is a direct current motor; and the high-precision weak current detection module is a low-noise operational amplifier.

[0029] As preferred:

[0030] The constant current power supply is used to supply a 4-20 mA current signal to the outside; and the external power supply is used to supply power to the power module.

[0031] The working method of the digital flow current measurement device comprises the following steps:

[0032] The power module supplies power to the electrical equipment while performing overcurrent protection;

[0033] The driving device drives the plunger to reciprocate up and down in the detection chamber to drive the sampling water to perform piston movement, and the piston movement of the sampling water generates a weak alternating current with a frequency of Hz on the electrode, and the frequency of the alternating current is the rotation speed frequency of the driving device; the locked-rotor protection and rotation speed control device performs locked-rotor protection and rotation speed control on the driving device, and the driving device is controlled at a fixed frequency;

[0034] The electrode sends the analog signal of the weak alternating current to the analog signal acquisition module in the digital transmitter; the digital signal acquisition module converts the analog signal of the weak alternating current into a digital signal, and sends the digital signal to the central processor;

[0035] The central processor performs logical operation on the digital signal by using the SCV algorithm based on the RMS value, comprehensively determines the positive and negative polarity of the measured water quality through the rotation speed phase and the dosing trend, can realize data storage, historical trend review, setting value modification, etc., provides a maintenance port, etc., the method of combining the SCV dynamic trend determination wastewater polarity based on the RMS value improves the accuracy of the SCV operation; sends the flow current information to be displayed, the positive and negative polarity of the measured water quality and the configuration information to the display device, and controls the output of the constant current power supply within 4-20 mA.

[0036] As preferred, the specific way in which the central processor performs logical operation on the digital signal by using the SCV algorithm based on the RMS value, and comprehensively determines the positive and negative polarity of the measured water quality through the rotation speed phase and the dosing trend is as follows:

[0037] Add a stirrer speed sensor to obtain the stirrer speed signal, and the central processing unit obtains the pulse signal of the dosing pump;

[0038] Perform wavelet noise reduction on digital signals, perform FFT spectrum analysis on agitator speed signals, and calculate trend slope on pulse signals of dosing pumps;

[0039] The digital signal after wavelet denoising, the stirrer speed signal after FFT spectrum analysis, and the calculated trend slope are subjected to feature fusion;

[0040] The fused features are input into the polarity decision tree, and the positive and negative polarity of the measured water quality is comprehensively determined by the speed phase and dosing trend; logical operations are performed through the SCV algorithm based on the RMS value to output a polarity label with confidence.

[0041] The beneficial effects of the present invention are:

[0042] The probe's insulation layer is made of polyimide or polyetheretherketone (PEEK), and the insulation layer of the cables between the electrical devices is also made of polyimide or polyetheretherketone (PEEK). It can withstand a cumulative radiation dose of 10kGy (detector) and 535Gy (transmitter). It uses an inverted "X"-shaped electrode with a silver-based Ag / AgCl active layer. It has the advantages of high temperature resistance, anti-electromagnetic interference, high reliability, high precision, and wide frequency response. It can meet the needs of aerospace, petrochemical, nuclear industry and other fields for high-reliability vibration monitoring, and has broad application prospects.

[0043] Using a picoamp-level analog signal acquisition module (including a low-noise op amp) and a high-resolution analog-to-digital converter, the system directly digitizes the raw microcurrent, eliminating power frequency interference in the analog amplification process and reducing zero-point drift to the required range. The central processing unit uses an RMS-based SCV algorithm, integrating wavelet noise reduction, FFT spectrum analysis, and trend slope calculation, to output a polarity label with confidence, reducing the rate of polarity misjudgment.

[0044] It uses a multi-protocol digital interface that supports Modbus RTU (RS485), HART (4-20mA), TCP / IP (Ethernet), and LoRa / WiFi wireless protocols. Combined with the MQTT protocol, it can achieve remote data storage and synchronization with the cloud platform. The stall protection device can monitor the motor current in real time, shortening the response time of the equipment and improving the real-time dosing control.

[0045] In summary, this invention addresses the core issues of existing technologies, such as low accuracy, poor environmental adaptability, and limited functionality, providing a highly reliable solution for streaming current monitoring in high-irradiation and strong electromagnetic interference scenarios. It is suitable for use in wastewater treatment in the nuclear industry, engine vibration monitoring and aircraft structural health monitoring in the environmental field, reactor and pipeline vibration monitoring in the petrochemical industry, high-voltage transmission line vibration monitoring, and wind turbine vibration monitoring, among other scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a structural schematic diagram of the streaming current detector of the present invention;

[0047] Figure 2 This is a structural diagram of a digital transmitter of the present invention;

[0048] Figure 3 This is a flow chart for determining the positive and negative polarity of the water quality being measured according to the present invention.

[0049] Explanation of the accompanying symbols: photoelectric switch 1, DC motor 2, stall protection and speed control device 3, probe 4, detection chamber 5, plunger 6, electrode 7, sample water inlet 8, digital transmitter 9, sample water outlet 10, power module 11, external power supply 12, analog signal acquisition module 13, digital signal acquisition module 14, central processing unit 15, display device 16, constant current power supply 17. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the following examples. The following examples are provided only to facilitate understanding of the present invention. It should be noted that, without departing from the principles of the present invention, it is possible for a person skilled in the art to make various modifications to the present invention, and such improvements and modifications fall within the scope of the claims of the present invention.

[0051] Example 1

[0052] like Figure 1 and Figure 2 As shown, a digital flowing current measuring device includes: a flowing current detector and a digital transmitter 9; the flowing current detector is electrically connected to the digital transmitter 9;

[0053] The flowing current detector includes a detection chamber 5, a plunger 6, a probe 4 (an electrode made of silver (8 mm in diameter and 0.5 mm in thickness)), an electrode 7, a DC motor 2 (a 24 V DC brushless motor (rated torque 0.25 N m) with PWM speed regulation to achieve 200-2000 rpm stepless speed change (resolution ±1 rpm)), a stall protection and speed control device 3; the detection chamber 5 is provided with a sampling water inlet 8 and a sampling water outlet 10. The detection chamber 5 is used to hold sampling water. The sampling water flows into the detection chamber from the sampling water inlet and passes through the plunger and After passing through the space between the detection chambers, the sampled water flows out of the detection chamber from the sampling outlet; a plunger 6 is provided above the detection chamber 5, the plunger 6 is connected to the DC motor 2, and the DC motor 2 is electrically connected to the stall protection and speed control device 3; a probe 4 is provided in the detection chamber 5, the probe 4 is electrically connected to the electrode 7, the electrode 7 is electrically connected to the digital transmitter 9 for collecting the motor speed signal, and the digital transmitter 9 is electrically connected to the photoelectric switch 1; the digital transmitter 9 includes a power supply module 11, an analog signal acquisition module 13 (pA level analog signal acquisition module), a digital signal acquisition module 14, and a central processing unit 15 (ARM Cortex-M4 core MCU, such as ST STM32F407), display device 16 (resistive touch screen) and constant current power supply 17, external power supply 12 is electrically connected to power module 11, power module 11 is electrically connected to DC motor 2, analog signal acquisition module 13, digital signal acquisition module 14 and central processing unit 15; analog signal acquisition module 13 is electrically connected to digital signal acquisition module 14, digital signal acquisition module 14 is electrically connected to central processing unit 15, central processing unit 15 is electrically connected to display device 16 and constant current power supply 17; electrodes are in an inverted "F" shape along the two side walls and bottom of detection chamber 5, and a polytetrafluoroethylene insulating layer with a thickness of 3mm is provided in probe 4 to prevent current leakage; constant current power supply 17 is used to supply a current signal of 4 to 20mA to the outside; external power supply 12 is used to supply power to power module 11; the surface of silver electrode (probe 4) is electrochemically oxidized to form an Ag / AgCl active layer, which can achieve a 3-fold increase in ion exchange efficiency (compared to traditional graphite electrode); 1pA detection sensitivity is still maintained in low conductivity medium (<10μS / cm).

[0054] The DC motor 2 is used to drive the plunger 6 to reciprocate up and down in the detection chamber 5, causing the sampled water to perform piston motion. The piston motion of the sampled water is used to generate a weak AC current with a frequency of 4 Hz on the electrode 7. The frequency of the AC current is the rotational frequency of the DC motor 2. The stall protection and speed control device 3 is used to provide stall protection and speed control for the DC motor 2. The DC motor 2 is adaptively controlled with a fixed frequency. The specific method for performing stall protection is: real-time monitoring of the current of the DC motor 2 (sampling rate 10 kHz). When the current is greater than 150% of the rated value for 100 ms, a reverse pulse is triggered to release the jam (pulse width 20 ms). After three stalls, the machine automatically shuts down and sends an alarm code E01 to the display device 16.

[0055] The electrode 7 is used to send an analog signal of a weak alternating current to the analog signal acquisition module 13 in the digital transmitter 9; the power supply module 11 is used to supply power to the electrical equipment, and the power supply module 11 is provided with an overcurrent protection circuit; the digital signal acquisition module 14 is used to convert the analog signal of the weak alternating current into a digital signal and send the digital signal to the central processing unit 15; the central processing unit 15 is used to perform logical operations on the digital signal, send data to be displayed to the display device 16, and send instructions to the constant current power supply 17 to control its output voltage range; the display device 16 is used to display the data to be displayed;

[0056] The insulation layer of the probe 4 is made of a radiation-resistant material such as polyimide (PI) or polyetheretherketone (PEEK). The insulation layer of the cables between the electrical devices is also made of a radiation-resistant material such as polyimide (PI) or polyetheretherketone (PEEK).

[0057] The analog signal acquisition module 13 includes a high-precision weak current detection module (low-noise operational amplifier) ​​and a high-resolution analog-to-digital converter (≥16-bit Σ-Δ ADC, reference voltage: ±2.5V, default 100SPS sampling rate (configurable to 10SPS to 10kSPS via the SPI interface to adapt to different water quality change rate scenarios), input range: ±5V (matching the front-end output)); the high-precision weak current detection module is electrically connected to the electrode 7 in the flowing current detector, the high-precision weak current detection module is also electrically connected to the high-resolution analog-to-digital converter, and the high-resolution analog-to-digital converter is electrically connected to the central processing unit 15;

[0058] Electrode 7, used to sense the weak alternating current generated by the piston movement of the sampled water and convert it into a micro-current signal, which is then sent to a high-precision micro-current detection module;

[0059] A high-precision weak current detection module is used to amplify and condition the micro-current signal and send the amplified and conditioned micro-current signal to a high-resolution analog-to-digital converter;

[0060] A high-resolution analog-to-digital converter is used to digitally sample the amplified and conditioned microcurrent signal, with a digital sampling accuracy of not less than 16 bits, and transmit the digitally sampled microcurrent signal to the central processing unit 15;

[0061] The central processing unit 15 is used to process the micro-current signal after digital sampling, determine the positive and negative polarity of the measured water quality in real time, and display and output it;

[0062] The streaming current detector is also provided with a solenoid valve, which is used for regularly flushing the probe 4;

[0063] A digital communication interface module is also provided, the central processing unit 15 is electrically connected to the digital communication interface module, and the digital communication interface module is electrically connected to the display device 16. The multi-protocol compatible digital communication interface module is specifically configured as follows: RS485+Modbus RTU: baud rate 9600-115200bps, 4-20mA+HART: implemented by AD5421 chip, Ethernet+TCP / IP: using W5500 hardware protocol stack; locking in industrial interface standards to strengthen market application barriers;

[0064] a digital communication interface module for sending the flowing current value and device status information to the display device 16;

[0065] The entire streaming current measurement device in this embodiment is installed on the sampling pipeline in the flocculation dosing control system for radioactive wastewater treatment in a nuclear power plant. The streaming current value is uploaded to the central processor 15 (Modbus RTU) in real time. The central processor 15 adjusts the dosing pump frequency according to the set value (SC = ±10), and the central processor 15 synchronizes the data to the cloud platform via the MQTT protocol.

[0066] Compared with the traditional analog device, the performance parameters of the digital streaming current measuring device used in this embodiment are compared in Table 1 below:

[0067] Table 1 Comparison of test performance between the digital streaming current measuring device used in this embodiment and the traditional analog device

[0068] Test item Conventional analog device Digital flow current measuring device Zero drift (8h) ± 15 μA ± 0.8 μA Temperature influence error 5％ / 10℃ 0.7％ / 10℃ Response time 10～20s 2s

[0069] The entire streaming current measuring device in this embodiment has passed the radiation aging test, wherein the streaming current detector can withstand a cumulative radiation measurement of 10 kGy, and the digital transmitter can withstand a cumulative radiation of 535 Gy.

[0070] Example 2

[0071] On the basis of Example 1, Figure 3As shown, the working method of the digital streaming current measuring device in Example 1 includes the following steps:

[0072] The power module 11 provides power to the electrical equipment while performing overcurrent protection;

[0073] The driving device drives the plunger 6 to reciprocate up and down in the detection chamber 5, driving the sampled water to perform piston motion. The piston motion of the sampled water generates a weak AC current with a frequency of 4 Hz on the electrode 7. The frequency of the AC current is the rotational frequency of the driving device. The stall protection and speed control device 3 provides stall protection and speed control for the driving device. The driving device is adaptively controlled by a fixed frequency.

[0074] The electrode 7 sends an analog signal of a weak alternating current to the analog signal acquisition module 13 in the digital transmitter 9; the digital signal acquisition module 14 converts the analog signal of the weak alternating current into a digital signal and sends the digital signal to the central processing unit 15;

[0075] The central processing unit 15 uses the SCV algorithm based on the RMS value to perform logical operations on the digital signal, and comprehensively determines the positive and negative polarity of the measured water quality through the rotational speed phase and the dosing trend:

[0076] An agitator speed sensor is added to obtain the agitator speed signal, and the central processor 15 obtains the pulse signal of the dosing pump;

[0077] Perform wavelet noise reduction on digital signals, perform FFT spectrum analysis on agitator speed signals, and calculate trend slope on pulse signals of dosing pumps;

[0078] The digital signal after wavelet denoising, the stirrer speed signal after FFT spectrum analysis, and the calculated trend slope are subjected to feature fusion;

[0079] The fused features are input into the polarity decision tree, and the positive and negative polarity of the measured water quality is comprehensively determined by the speed phase and the dosing trend. The SCV algorithm based on the RMS value is used for logical operation to output a polarity label with confidence. The system can realize data storage, historical trend review, set value modification, etc., and provide an intelligent operation and maintenance port. The method of determining wastewater polarity based on the RMS value SCV algorithm combined with the SCV dynamic trend improves the accuracy of SCV operation.

[0080] The flow current information to be displayed, the positive and negative polarity of the measured water quality and the configuration information are sent to the display device 16, and the output of the constant current power supply 17 is controlled within 4 to 20 mA.

[0081] In summary, the method of this embodiment uses a high-precision ADC to directly digitally sample the original weak current signal generated by the sensor probe, greatly simplifying the front-end processing of the analog signal and improving the system's anti-interference capability. It also utilizes an embedded processor to execute advanced digital signal processing algorithms to process the digitized original signal in real time, accurately calculating and outputting the flowing current value. It also integrates a digital communication interface to achieve digital output and remote configuration management of measurement data, providing a soft operation interface and displaying SCV and flowing current trend graphs. This invention is particularly suitable for online optimization and control of the coagulation and dosing process in water treatment, providing a more reliable and intelligent digital measurement tool for improving water quality and reducing drug consumption.

Claims

1. A digital streaming current measuring device, characterized in that: include: A flow current detector and a digital transmitter (9); the flow current detector is electrically connected to the digital transmitter (9); the flow current detector is used to collect the weak alternating current generated when the sampled water is sheared, and the digital transmitter (9) is used to process the weak alternating current, determine the positive and negative polarity of the measured water quality, and display and output; the flow current detector has a radiation-resistant part, is electromagnetically compatible, and is self-zeroing; the digital transmitter (9) also has a radiation-resistant part.

2. The digital streaming current measuring device according to claim 1, characterized in that: The streaming current detector comprises a detection chamber (5), a plunger (6), a probe (4), an electrode (7), a driving device, a stall protection and speed control device (3); the detection chamber (5) is provided with a sampling water inlet (8) and a sampling water outlet (10), and the detection chamber (5) is used to contain the sampling water; the plunger (6) is provided above the detection chamber (5), the plunger (6) is connected to the driving device, and the driving device is electrically connected to the stall protection and speed control device (3); the detection chamber (5) is provided with the probe (4), the probe (4) is electrically connected to the electrode (7), the electrode (7) is electrically connected to a digital transmitter (9) for collecting the motor speed signal, and the digital transmitter (9) is electrically connected to the photoelectric switch (1); the The digital transmitter (9) includes a power supply module (11), an analog signal acquisition module (13), a digital signal acquisition module (14), a central processing unit (15), a display device (16) and a constant current power supply (17), wherein the external power supply (12) is electrically connected to the power supply module (11), and the power supply module (11) is electrically connected to the driving device, the analog signal acquisition module (13), the digital signal acquisition module (14) and the central processing unit (15); the analog signal acquisition module (13) is electrically connected to the digital signal acquisition module (14), the digital signal acquisition module (14) is electrically connected to the central processing unit (15), and the central processing unit (15) is electrically connected to the display device (16) and the constant current power supply (17); The driving device is used to drive the plunger (6) to move up and down in the detection chamber (5) to drive the sampled water to perform piston movement, and the piston movement of the sampled water is used to generate a weak alternating current on the electrode (7); the stall protection and speed control device (3) is used to perform stall protection and speed control on the driving device; The electrode (7) is used to send the analog signal of the weak alternating current to the analog signal acquisition module (13) in the digital transmitter (9); the power supply module (11) is used to supply power to the electrical equipment, and the power supply module (11) is provided with an overcurrent protection circuit; the digital signal acquisition module (14) is used to convert the analog signal of the weak alternating current into a digital signal and send the digital signal to the central processing unit (15); the central processing unit (15) is used to perform a logical operation on the digital signal, send the flowing current value and device status information to the display device (16), and send an instruction to control the output voltage range of the constant current power supply (17); the display device (16) is used to display the flowing current value and device status information; The insulating layer of the probe (4) is made of polyimide or polyetheretherketone, and the insulating layers of the cables between the electrical devices are also made of polyimide or polyetheretherketone.

3. The digital streaming current measuring device according to claim 2, characterized in that: The analog signal acquisition module (13) includes a high-precision weak current detection module and an analog-to-digital converter; the high-precision weak current detection module is electrically connected to the electrode (7) in the flowing current detector, the high-precision weak current detection module is also electrically connected to the analog-to-digital converter, and the analog-to-digital converter is electrically connected to the central processing unit (15); The electrode (7) is used to sense the weak alternating current generated thereon by the piston movement of the sampled water and convert it into a microcurrent signal, which is used to send the microcurrent signal to the high-precision weak current detection module; The high-precision weak current detection module is used to amplify and condition the microcurrent signal, and to send the amplified and conditioned microcurrent signal to the analog-to-digital converter; The analog-to-digital converter is used to digitally sample the amplified and conditioned microcurrent signal and send the digitally sampled microcurrent signal to the central processing unit (15); The central processing unit (15) is used to process the micro-current signal after the digital sampling and determine the positive and negative polarity of the measured water quality in real time; The streaming current detector is also provided with a solenoid valve, which is used for regularly flushing the probe (4).

4. The digital streaming current measuring device according to claim 3, characterized in that: A digital communication interface module is also provided, the central processing unit (15) is electrically connected to the digital communication interface module, and the digital communication interface module is electrically connected to the display device (16); The digital communication interface module is used to send data to be displayed to the display device (16), wherein the data to be displayed includes the flowing current value and device status information.

5. The digital streaming current measuring device according to claim 4, characterized in that: The digital communication interface module supports at least one of the following industrial standard protocols: the Modbus protocol configured on the RS485 interface, the HART protocol configured for 4 to 20 mA analog signals, the TCP or IP protocol configured for Ethernet, and the wireless protocol configured for the wireless communication module; wherein the wireless protocol is the LoRa protocol, the WiFi protocol or the Bluetooth protocol; and the analog signal acquisition module (13) is a pA-level analog signal acquisition module.

6. The digital streaming current measuring device according to claim 1, characterized in that: The probe (4) is an electrode made of silver, and the surface of the silver electrode is subjected to electrochemical oxidation treatment to form an Ag / AgCl active layer; the electrode is in an inverted "F" shape along the two side walls and the bottom of the detection chamber (5), and an insulating layer made of polytetrafluoroethylene is provided inside the probe (4).

7. The digital streaming current measuring device according to claim 2, characterized in that: The driving device is a DC motor (2); and the high-precision weak current detection module is a low-noise operational amplifier.

8. The digital streaming current measuring device according to claim 2, characterized in that: The constant current power supply (17) is used to supply a current signal of 4 to 20 mA to the outside; and the external power supply (12) is used to supply power to the power supply module (11).

9. A method for operating the digital streaming current measuring device according to any one of claims 2 to 8, characterized in that: The following steps are involved: The power module (11) provides power to the electrical equipment while performing overcurrent protection; The driving device drives the plunger (6) to reciprocate up and down in the detection chamber (5), driving the sampled water to perform piston movement, and the piston movement of the sampled water generates a weak alternating current on the electrode (7); the stall protection and speed control device (3) performs stall protection and speed control on the driving device; The electrode (7) sends the analog signal of the weak alternating current to the analog signal acquisition module (13) in the digital transmitter (9); the digital signal acquisition module (14) converts the analog signal of the weak alternating current into a digital signal, and sends the digital signal to the central processing unit (15); The central processing unit (15) performs logic operations on the digital signal using an SCV algorithm based on the RMS value, and comprehensively determines the positive and negative polarity of the measured water quality through the rotational speed phase and the dosing trend; sends the flow current information to be displayed, the positive and negative polarity of the measured water quality, and configuration information to the display device (16), and controls the output of the constant current power supply (17) within 4 to 20 mA.

10. The operating method of the digital streaming current measuring device according to claim 9, characterized in that: The central processing unit (15) uses the SCV algorithm based on the RMS value to perform a logical operation on the digital signal, and the specific method of comprehensively determining the positive and negative polarity of the measured water quality through the rotation speed phase and the dosing trend is as follows: A stirrer speed sensor is added to obtain a stirrer speed signal, and the central processor (15) obtains a pulse signal of a dosing pump; Performing wavelet noise reduction on the digital signal, performing FFT spectrum analysis on the stirrer speed signal, and performing trend slope calculation on the pulse signal of the dosing pump; Performing feature fusion on the digital signal after wavelet denoising, the stirrer speed signal after FFT spectrum analysis, and the calculated trend slope; The fused features are input into the polarity decision tree, and the positive and negative polarity of the measured water quality is comprehensively determined by the speed phase and dosing trend; logical operations are performed through the SCV algorithm based on the RMS value to output a polarity label with confidence.

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