Jiangsu Jinyuan Instrument Engineering Co., Ltd. is a manufacturer of high quality flowmeters for Jiangsu brand. Main products: electromagnetic flowmeters, ultrasonic flowmeters, orifice flowmeters, sewage flowmeters, open channel flowmeters, V-cone flowmeters, gasoline flowmeters, etc. , Our factory specializes in manufacturing flow meters, pressure meters, temperature meters, liquid level meters, calibration meters, instrument electrical cabinets, wire and cable and other instruments. Welcome new and old customers advice and procurement, we have to serve you!
Metallurgical enterprises are continuous integrated operations. They are not only large consumers of energy, but also large consumers of fresh water. Water is a special kind of resource on the earth. In particular, fresh water is on the verge of scarce resources. The cost per ton of groundwater has increased substantially year by year. Water conservation is no longer just a corporate economic issue. What is more important is a major social issue that concerns the sustainable development of the company and the harmonious development of the people's livelihood.
Measurement is the measurement technology support for the company's water conservation performance. Measurement has an irreplaceable display and guidance role for companies to reasonably control water use. The support of measurement technology plays a fundamental role in the realization of enterprise information management.
Water metering in the enterprise mostly uses mechanical water meters. It has the following drawbacks: (1) Low precision, large positive and negative deviations; (2) Vulnerability; (3) inconvenient calibration or calibration; (4) Water pressure loss caused by pipe shrinkage (5) Real-time traffic cannot be displayed; (6) In particular, metering data cannot be transmitted remotely over the network and cannot meet the needs of enterprise informationization. After technical personnel reviewed the data of industrial liquid flow meters and compared them in kind with the needs of enterprise information construction, most of them turned to ultrasonic flow meters for water measurement. It is understood that the metering divisions of large metallurgical enterprise groups such as Laiwu Steel and Jinan Iron & Steel have gradually adopted ultrasonic flowmeters for water measurement between the head office and the ironworks, steelworks, rolling mills, and power plants, and try to use portable methods. Comparison.
A, ultrasonic flow meter measurement principle
Ultrasonic flowmeter is a non-contact flowmeter. The working principle is: When the ultrasonic wave propagates in the fluid, the propagation velocity of the ultrasonic wave is affected by the flow velocity of the fluid. By measuring the propagation velocity of the ultrasonic wave in the fluid, the flow velocity of the fluid can be detected and the flow rate can be converted.
The most widely used time difference method for ultrasonic flowmeters is used as an example. When the ultrasonic wave propagates in a fluid, the propagation speed of the ultrasonic wave in the downstream direction increases, and the direction of the countercurrent decreases. That is, the same propagation distance has a different propagation time, and is reused. The relationship between the difference in the propagation speed and the flow rate of the fluid to be measured is obtained by calculating the flow rate and converting the flow rate. That is, when the ultrasonic beam propagates between the “upstream sensor†and the “downflow sensor†in the direction of the flow of the aqueous medium in the pipe, the flow of the water causes a slight change in the propagation time of the ultrasonic beam relative to the static propagation, and this propagation time The change is proportional to the flow rate of water, which is the measurement principle of the time-difference ultrasonic flowmeter.
The theoretical expression of the relationship is as follows: V=MD/sin2θ×△T/TupTdown
Among them, M—is the number of straight propagation times of ultrasonic beams in water
Θ—angle between ultrasonic beam and water flow direction
Tup—The travel time of the ultrasonic beam in the positive direction (the travel time from the upstream sensor to the downstream sensor)
Tdown—The time in which the ultrasonic beam travels in the reverse direction (the travel time from the downstream sensor to the upstream sensor)
â–³T=Tup-Tdown
Second, the characteristics of ultrasonic flowmeter
Ultrasonic flowmeters are based on microprocessor technology and are mostly designed using integrated circuits and low-voltage wide-pulse emission technologies. In the measurement technology, in order to achieve higher resolution and greater measurement range, use 0.1ns ultra-high resolution time measurement circuit. It is used exclusively for measuring liquid media, especially water. Its remarkable feature is: Accuracy class is ± 1.0%, can be installed under pressure without stopping production, the host can be installed in the value control room can also output current, pulse and other standard signals and can use RS232 or RS485 interface communication for measurement data remote Transmission. In addition, the flowmeter has the advantages of high reliability, low power consumption, anti-jamming, and easy installation and maintenance.
Third, the construction and installation of ultrasonic flowmeter
1, the structure of ultrasonic flowmeter
Ultrasonic flowmeters can generally be divided into field sensors (ie, probes), transmission cables, and display three main parts of the host. The sensors are external clamp type, plug-in type, flange type (segment type), the display host is fixed and portable, and the portable host can be equipped with an external clamp sensor to compare the ultrasonic flowmeters that are fixed in online operation (on-site calibration ) And the installation is very simple (about 10 minutes).
2, the determination of ultrasonic flowmeter measuring point
The ultrasonic flowmeter needs to select an appropriate measurement point first, then input the water pipe parameter of the measurement point into the flowmeter, and finally install the sensor (that is, the probe) on the water pipe.
(1) General requirements for measuring points
Ultrasonic flowmeter measurement point requirements need to be in a certain length of straight pipe, that is, select the flow distribution of the pipe section to reduce the measurement error.
(2) Selection principle of measuring points
a. The measurement point should be selected from the upstream (water flow to the direction) 10 times the length of the pipe, the distance from the downstream (water flow direction) 5 times the pipe length of the uniform straight pipe section (that is, the upper and lower valves outside the length, or the point of inflection of the water pipe Outside this length).
b. The material of the straight section should be uniform and flawless to facilitate ultrasonic transmission.
c. The inner wall of the straight pipe section should be free of scale (if slight scale is available, steam or high-pressure water can be used for purging).
d. The straight section must be filled with water (regardless of vertical or horizontal sections).
3, ultrasonic flowmeter sensor installation
The installation quality of the ultrasonic flowmeter sensor is directly related to the accuracy, reliability, and operational reliability of the water flow measurement.
(1) Classification of Ultrasonic Flowmeter Sensors (Probes)
The commonly used ultrasonic flowmeter sensors have the following three installation methods:
External clamp sensor—When mounting, it is necessary to smooth the intended installation position of the outer wall of the tube, and then use a coupling agent to attach the sensor (probe) to the outer wall of the tube and fix it with a special clamping device. This method can conveniently measure water flow outside the tube and is also suitable for portable use. The disadvantage is that it is easy to influence the stability of the measurement due to the bad signal receiving status caused by improper handling of the coupling agent.
Plug-in sensor—Insert the sensor (probe) into the tubing during production without using a drill tool. The advantage is that a stable and reliable measurement can be achieved in the case of fouling of the inner wall of the water pipe or air entrainment in the water.
Segment Sensors—When installed, the selected straight section needs to be cut and flanged. The product has been specifically factory-calibrated. The advantage is that the sensor can be repaired without stopping production. It is characterized by high measurement accuracy.
(2) Installation of ultrasonic flowmeter sensor (probe)
Ultrasonic flowmeter sensor (probe) installation position is generally selected two sensor (probe) tube axis in the direction of the pipeline axis of the water pipeline or an angle of 45 degrees with the axis of the tube axis.
Ultrasonic flowmeter sensor (probe) installation methods Z, V, N, W. Among them, the N and W methods are suitable for water pipelines with a diameter of 50 mm or less, and are rarely used due to the difficulty of use and high cost performance. There are two common ways:
a, "V" installation
"V" type installation is the standard installation method, and the range of measurable pipe diameter is 25mm-400mm. When installing the sensor (probe), it is necessary to pay attention to the horizontal alignment of the upstream and downstream sensors (probes) so that the center line of the sensor is horizontally aligned with the axis of the water delivery pipe. (See illustration in the illustration)
b, "Z" installation
The "Z" type installation is generally applicable to the distortion of the "V" type installation signal when the water pipeline is rough or the water medium is not very clean or the inner wall of the pipeline is scaled. Generally speaking, it is more appropriate to use a “Z†type installation for a water pipeline with a diameter of 300 mm or more, and a range of 100 to 600 mm for a “Z†type installation. When installing the sensor (probe), it must be noted that the upstream and downstream sensors (probe) are in the same plane as the axis of the water delivery pipe, and the upstream sensor (probe) is in the low position and the upstream sensor (probe) is in the high position. (See illustration in the illustration)
(3) Installation inspection of ultrasonic flowmeter sensor probe
aã€Mainly check if the sensor (ie probe) is installed in a suitable location.
b. Whether the combination with the outer wall of the water pipe is smooth or tight.
c. Check the signal strength and signal quality by the host computer to observe whether the sensor can receive the ultrasonic signal that makes the host work normally.
4, ultrasonic flow meter debugging
(1) According to the requirements of the flowmeter, input the pipeline parameters and record them.
(2)Adjust the installation position, spacing, and pipe bonding degree of the upstream and downstream sensors (probe), and adjust the signal strength received in both upstream and downstream directions to the strongest (the greater the signal strength, the more stable and reliable the measurement value is. The bigger, the longer it can run reliably.)
5. Remote transmission and sharing of ultrasonic flowmeter measurement data
The technicians usually communicate with ultrasonic flowmeters through PCs or other communication devices. They connect the standard serial port of the ultrasonic flowmeter with the serial port of the host computer with an appropriate serial port cable, and send pre-set commands on the host computer with software. , can make the flowmeter send out the relevant response signal.
The technician uses the identification code of the ultrasonic flowmeter as the network address code, uses the corresponding command set as the communication protocol, uses the current loop of the flowmeter and its OCT output to control the opening of the stepping (or analog) solenoid valve, and the relay output It can control the power-on and power-off of other equipments, and can realize data acquisition and remote control. (The data transmission hardware uses RS232 or RS485 interface to communicate at a closer distance, and adopts current loop or wireless transmission at a longer distance) through Ethernet. The network will be flow meter data into the corporate network to achieve the company's relevant secondary units of data sharing. And realized the real-time monitoring status of water metering.
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