The research and development of intelligent electromagnetic flowmeter has been developed to practical application in all walks of life

　　China began to develop electromagnetic flowmeter as early as the late 1950s, and Shanghai Guanghua Instrument Factory began to provide products to the society in the early 1960s. In 1967, everyone gathered their wisdom to improve Ding's understanding of electromagnetic flowmeter. More importantly, the national electromagnetic flowmeter design laid the foundation for the later development of electromagnetic flowmeter in China, trained talents, and designed and developed a series of domestic products in less than a year. In the mid-1970s, affected by the influence of advanced industrial countries on electromagnetic flowmeter, the theoretical research of electromagnetic flowmeter in China also reached a climax. In June 1975, the famous physicist, Professor Wang Zhuxi and Professor Zhao Kaihua of Peking University were invited by Kaifeng instrument factory to make a rigorous mathematical analysis of the weight function theory of electromagnetic flowmeter and give a lecture, which led many universities such as Huazhong Institute of technology, Northeast Institute of technology and Shanghai Jiaotong University to actively participate in the research of electromagnetic flowmeter theory, And developed our country's weighted distributed magnetic field electromagnetic flowmeter product. Our country's electromagnetic flowmeter is one of the high-tech products that have earlier and successfully taken the reform road of introducing foreign advanced technology and joint venture with foreign advanced enterprises. This not only makes the backbone manufacturers of electromagnetic flowmeter develop rapidly, but also drives the technological progress of other small and medium-sized enterprises producing electromagnetic flowmeter. At present, the production of electromagnetic flowmeter in China is mainly based on low-frequency rectangular cross excitation, and gradually enters the generation of weighted magnetic field and intelligent flow. The product caliber range is from 3mm to 30ffir Ⅱ nm, and the measurement accuracy is in the range of ± 0.3% R or ± 1% FS. The number of manufacturers has increased from 4 in the early 1980s to about 30 at present; The annual output has increased from less than 1000 sets to nearly 30000 sets today. No matter the level of manufacturing technology, development capacity or market development, the distance between our electromagnetic flowmeter and the world advanced level is shrinking rapidly.

　　China formulated the industry standard of electromagnetic flowmeter in 1980. With the development and progress of technology, it was revised in 1999, and the national standards equivalent to ISO international standards (IS0 9104: 199I and IS0 6817: 1992): CB / T 18659-2002 [performance evaluation method of electromagnetic flowmeter for measuring the flow of conductive liquid in closed pipeline] and CB factory R 1860-2002 [user {strike of electromagnetic flowmeter for measuring the flow of conductive liquid in closed pipeline] have been promulgated. So that our electromagnetic flowmeter can be in line with international standards in the future, which creates conditions for the development of our electromagnetic flowmeter( This article is compiled and published by Runzhong Instrument Technology Co., Ltd.) The historical process of the invention and gradual improvement of electromagnetic flowmeter. The invention of electromagnetic flowmeter is a landmark product for today's instrument industry. Since the invention of electromagnetic flowmeter, people have a new measurement method for the measurement of large and super large flow area in production and life. And this measurement method can measure the flow and velocity of conductive liquid in various channels. Human beings have made a big step forward in the technology of measuring flow. The basic working principle of electromagnetic flowmeter comes from the law of electromagnetic induction. The law of electromagnetic induction was discovered by British physicist Faraday in 1831. Faraday's law of electromagnetic induction says that when the conductor moves to cut the magnetic line of force in the magnetic field, an induced electromotive force perpendicular to the direction of the magnetic field and the direction of conductor movement will be induced at both ends of the conductor. The magnitude of the induced electromotive force is directly proportional to the magnetic induction intensity and motion speed.

　　Upward trend

　　In 1832, Faraday chose the geomagnetic field direction perpendicular to the water flow direction on both banks of the Waterloo Bridge on the Thames River, and put down two metal rods as electrodes to measure the flow velocity of the river. This is the first test of electromagnetic flowmeter in the world. However, due to electrochemical reaction, thermoelectric effect and other reasons, the measured signal is false, and the flow rate signal is short circuited by the riverbed. Coupled with the limitations of the measurement conditions at that time, he failed. Fortunately, in 1851, he saw the success of Williams and others' experiment of measuring tide in the English Channel by electromagnetic induction method. In 1917, Smith and spirian obtained the patent of using the principle of electromagnetic induction to manufacture ship velocimeter, and recommended the use of AC excitation to overcome the influence of water polarization, so as to open up the application of Ding electromagnetic velocimeter in oceanography. In 1930, Williams made the copper sulfate solution flow in a non-conductive circular tube placed in a DC magnetic field. The DC voltage between the two electrodes of the circular tube was directly proportional to the flow rate. This device became a simple electromagnetic flowmeter. Williams first used mathematical method to analyze the influence of velocity distribution in circular pipe on measurement, and put forward the theory that the percolation velocity distribution symmetrical to the central axis of the pipe does not affect the measurement accuracy of electromagnetic flowmeter. Although his analysis was mathematically wrong, he has since developed the basic theory of electromagnetic flowmeter. Around 1932, according to fabM's suggestion, biologists willama and A. Colin successfully used electromagnetic flowmeter to measure and record instantaneous arterial blood flow.

　　In the early 1960s, based on the mathematical analysis of electromagnetic flowmeter with infinite uniform magnetic field by A. Kolin and other predecessors, J. a shemliff completed the mathematical analysis of equal velocity under finite uniform magnetic field, and revealed the micro characteristics of induced electromotive force with the theory of weight function, which made the electromagnetic flowmeter have a systematic basic theory. At the same time, with the rapid development of electronic industry and the continuous improvement of industrial whiteness, the electromagnetic flowmeter is gradually improved. It has matured and developed into a flow instrument with excellent performance, which has been widely used in industry. From the late 1960s to the mid 1970s. With the in-depth study of the three-dimensional weight function, an electromagnetic flowmeter with a small weight redistribution magnetic field appears, which greatly shortens the limited length of the magnetic field and improves the insensitivity of the measurement to the flow velocity to a certain extent. At the same time, it is beneficial to simplify the manufacture of flowmeter and reduce the cost. The research results of three-dimensional weight function have great guiding significance for the development of electromagnetic flowmeter in this period. Due to the rapid development of integrated circuits and the higher performance requirements of flow measurement instruments put forward by the world energy crisis, a new technology of low-frequency rectangular cross excitation appeared. The low-frequency rectangular cross excitation electromagnetic flowmeter integrates the advantages of the AC excitation flowmeter in suppressing the polarization interference in the DC magnetic field signal and reducing the electromagnetic induction interference signal component contained in the signal in the AC magnetic field flowmeter, improves the zero point stability, sensitivity and measurement accuracy of the flowmeter, reduces the power consumption and solves the problems of interchangeability, It has formed a climax of the development of electromagnetic flowmeter.

　　Since the 1980s, microelectronic technology and computer technology have developed rapidly. Make the manufacturing technology of electromagnetic flowmeter more mature and perfect, and expand its application field. Modern electromagnetic flowmeter adopts single chip microcomputer technology and digital processing methods to continuously improve the measurement accuracy and performance of electromagnetic flowmeter, and can make full use of the advantages of computer with information storage, time-sharing processing, operation and control ability. Therefore, it is easy to realize additional functions such as two-way measurement, air traffic control detection, multi range automatic switching, man-machine dialogue, communication with host computer, self diagnosis and so on. The new generation of electromagnetic flowmeter with HART protocol and other fieldbus provides conditions for users to realize new fieldbus production control and management. Therefore, the one-piece, two-wire, explosion-proof and high-voltage electromagnetic flowmeter with communication function is becoming more and more popular in the automatic control of industrial production processes such as chemical industry, petroleum, iron and steel, metallurgy and so on. With the expansion of application field, various new conductive liquid flow measurement instruments and systems using electromagnetic induction method have emerged, such as capacitive electromagnetic flowmeter capable of measuring low conductivity, non full pipe electromagnetic flow meter for measuring gravity drainage, submersible electromagnetic flowmeter for open channel measurement The electromagnetic current meter which can measure the point velocity of open channel and large-diameter pipeline, the inserted electromagnetic flowmeter and the open channel measurement system composed of electromagnetic velocity water level method are used. China began to develop electromagnetic flowmeter as early as the late 1950s, and Shanghai Guanghua Instrument Factory began to provide products to the society in the early 1960s. In 1967, everyone gathered their wisdom to improve Ding's understanding of electromagnetic flowmeter. More importantly, the national electromagnetic flowmeter design laid the foundation for the later development of electromagnetic flowmeter in China, trained talents, and designed and developed a series of domestic products in less than a year.

　　In the mid-1970s, affected by the influence of advanced industrial countries on electromagnetic flowmeter, the theoretical research of electromagnetic flowmeter in China also reached a climax. In June 1975, the famous physicist, Professor Wang Zhuxi and Professor Zhao Kaihua of Peking University were invited by Kaifeng instrument factory to make a rigorous mathematical analysis of the weight function theory of electromagnetic flowmeter and give a lecture, which led many universities such as Huazhong Institute of technology, Northeast Institute of technology and Shanghai Jiaotong University to actively participate in the research of electromagnetic flowmeter theory, And developed our country's weighted distributed magnetic field electromagnetic flowmeter product. Our country's electromagnetic flowmeter is one of the high-tech products that have earlier and successfully taken the reform road of introducing foreign advanced technology and joint venture with foreign advanced enterprises. This not only makes the backbone manufacturers of electromagnetic flowmeter develop rapidly, but also drives the technological progress of other small and medium-sized enterprises producing electromagnetic flowmeter. At present, the production of electromagnetic flowmeter in China is mainly based on low-frequency rectangular cross excitation, and gradually enters the generation of weighted magnetic field and intelligent flow. The product diameter range is 3mm to 3mm, and the measurement accuracy is within ± 0.3% R or ± 1% FS. The number of manufacturers has increased from 4 in the early 1980s to about 30 at present; The annual output has increased from less than 1000 sets to nearly 30000 sets today. No matter the level of manufacturing technology, development capacity or market development, the distance between our electromagnetic flowmeter and the world advanced level is shrinking rapidly.

　　China formulated the industry standard of electromagnetic flowmeter in 1980. With the development and progress of technology, it was revised in 1999, and the national standards equivalent to ISO international standards (IS0 9104:199i and IS0 6817:1992): CB / T 18659-2002 [measurement of conductive liquid flow in closed pipeline and performance evaluation method of electromagnetic flowmeter] and CB / T 1860-2002 [measurement of conductive liquid flow in closed pipeline] have been promulgated. So that our electromagnetic flowmeter can be in line with international standards in the future, which creates conditions for the development of our electromagnetic flowmeter.