At home and abroad on the status quo of flow measuring
Instrument in the industrial production of flow measurement are widely used according to different conditions, such as the measured medium is two to the gas and liquid flow, multiphase flow, the density, viscosity and other physical state of the measured material change during measurement, measurement of environmental temperature and pressure there is a very big difference, so about the structure of the flow meter and industrial and signal processing part requirement is very high, need after continuous exploration and want to solve the issue of flow measuring. In recent years, although the rapid development of the flow measurement technology, but also improve the needs of industrial production, there is a great distance between the reality and our expectations. Furthermore, we in the selection of flow time, in addition to adapt to consider using conditions, but also other factors such as flow range, pressure, prices, explosion-proof grade, accuracy, corrosion resistance, anti-interference, and so on and so forth. To sum up, in order to meet the demand of different installation conditions, different measurement conditions, different using requirements, various types of flowmeter instrument so arises at the historic moment.
According to statistics, applied to industrial production today as many as dozens of varieties of various flow meters. More widely used, including electromagnetic flowmeter and mass flowmeter, turbine flowmeter, ultrasonic flowmeter, the coriolis flowmeter, nozzle flowmeter, orifice flow meter, and pig flowmeter, vortex flowmeter, venturi meter, open channel flow meter and so on more than a dozen. Every new technology was born, will attempt to its application in flow measurement, such as electromagnetic, laser, ultrasound is close to the result of times development. The use of electromagnetic flowmeter in all kinds of new type of flow meters are many, and occupies a stable market share.
Can say each has the vitality of the flowmeter, has its relatively application conditions have an advantage. The following alignment always part of the usage of flowmeter, characteristics, development status is described briefly.
Compared various flowmeter, differential pressure flowmeter has the advantages of low cost, simple structure, in the fluid flow metering, large, medium, and wide application. With V cone, venturi for typical reformed the old new type differential pressure type flowmeter differential pressure flowmeter pressure loss big shortcoming, and solve the straight pipe before and after the orifice meter required too long. Especially V cone flowmeter adopted a new structure form, the pressure loss decreased significantly, and the rectifier capacity. But it is worth noting that the differential pressure type flowmeter is heavily dependent on the indicator to measure differential pressure sensor measurement, and the differential value is proportional to the square root of the traffic, and other kinds of flowmeter range than the gap is very large. This can make differential pressure flowmeter range ratio and accuracy level is difficult. Under the working condition of small flow measurement, pressure fluctuation caused by the differential measurement error increases also limits the range than widened. Application of differential pressure type flow timing in different environment, also need to pay special attention to the measurement of pressure and temperature.
Turbine flowmeter, sonic nozzle, etc., the advantages of high accuracy have in common is this kind of flowmeter, and better stability, so the transfer value only can be used as flowmeter, applied to the standard flow meter. Under the condition of the turbine flowmeter using complex fluid, do not need to install filters and other auxiliary , and the pressure loss can be effectively controlled; And has high resolution and good repeatability.
For the use of economic development situation, the flow measurement of diameter increase, compared with other flowmeter, electromagnetic flowmeter, ultrasonic flowmeter with no loss of pressure, no moving parts, high measurement precision, etc. The big diameter application performance is more outstanding in the industry. Mass flowmeter with an outstanding performance in the industrial measurement, which has been widely applied in process control of, although the measuring accuracy is high, but there are sensitive to vibration of some products of zero drift and the pressure loss is too large when use should be paid close attention to.
Along with the national import and export trade of development, not only for trade settlement application conditions, such as to the accuracy of flowmeter is put forward to higher, the flow measurement value consistent requirements, device than as effective means to assure the value unification. The flow measuring instrument used for more than use transfer standard, in order to consistent and accurate flow value played a huge role.