Metering method of orifice-plate flowmeter
1.Measurement method of natural gas flowChina's natural gas measurement is usually expressed in volume, the statutory unit is cubic meters. The standard state of natural gas flow measurement in China is: absolute pressure is 0.101325MPa, temperature is 23.15 ℃. Natural gas flow metering methods are many, available flow meters are also many, according to the principle of work is roughly divided into: differential pressure flowmeter, volumetric flowmeter, Speed type Flowmeter 3 types. In terms of measurement standards, the world's most national standards of measurement gradually to the IS05167 "with the hole plate to measure the flow of fluid filled with circular tube," China's natural gas measurement standards are also revised to sy/t6143-1996 "natural gas flow standard orifice measurement method."
2.Survey of automatic metering of orifice-plate flowmeterThe so-called automatic metering, is to use the transmitter real-time detection of natural gas flow meter in the amount of temperature, pressure, pressure and other parameters, through the computer flow calculation software, to achieve the entire flow measurement link without human involvement in natural gas flow measurement. With the development of metrology technology and the popularization of computer application. There are more than 4 kinds of schemes to realize automatic metering of orifice-plate flowmeter.
2.1 Single Variable transmitter flow calculator (or industrial computer)Using a single variable analog transmitter to detect temperature, pressure, differential pressure, and the detection of electrical signals into the standard 4-20ma analog signal into the flow computer (or industrial computer) data acquisition card, through A/D conversion to digital, in the flow of computers (or industrial computer) The instantaneous flow of natural gas, cumulative flow and other auxiliary functions are calculated by the flow calculation software. This way is a traditional automatic metering mode, the disadvantage of collection, transmission as analog signal, anti-interference ability is poor, because of signal conversion problems such as precision measurement accuracy is difficult to improve, and hardware is more complex, intermediate links more, reliability is poor. Can be extended to: Single variable transmitter flow computer industrial control machine, so as to achieve flow calculation and display separate, improve the reliability and visibility of the system.
2.2 Variable transmitter flow calculator (or industrial computer)Using 1 multivariable Intelligent transmitter to detect temperature, pressure, differential pressure at the same time, using Fieldbus system, through the digital signal transmission, into the flow computer (or industrial computer) data acquisition card after the flow calculation software to calculate the natural gas instantaneous flow, cumulative flow and other functions to achieve. In this way, hardware connection simplifies a lot and improves the reliability and measurement accuracy of the system. But because the transmitter only detects the measurement signal does not carry on the data processing, therefore must in the school on time and the flow calculator implement the Union School. The main difference between the flow computer and the industrial control machine is the calculation part. Flow computer is a dedicated curing software to achieve the calculation and data storage, more stable and reliable, more trustworthy; Software computing on industrial control computer is generally self-developed, easy to upgrade software and maintenance, because of the large amount of calculation, especially the multi-channel measurement, the reliability is slightly worse. In order to increase the reliability of the system and intuitive operation interface, this method can also be extended to: Variable transmitter flow computer industrial control machine, that is, traffic flow computer to achieve flow calculation, industrial computer display.
2.Survey of automatic metering of orifice-plate flowmeterThe so-called automatic metering, is to use the transmitter real-time detection of natural gas flow meter in the amount of temperature, pressure, pressure and other parameters, through the computer flow calculation software, to achieve the entire flow measurement link without human involvement in natural gas flow measurement. With the development of metrology technology and the popularization of computer application. There are more than 4 kinds of schemes to realize automatic metering of orifice-plate flowmeter.
2.1 Single Variable transmitter flow calculator (or industrial computer)Using a single variable analog transmitter to detect temperature, pressure, differential pressure, and the detection of electrical signals into the standard 4-20ma analog signal into the flow computer (or industrial computer) data acquisition card, through A/D conversion to digital, in the flow of computers (or industrial computer) The instantaneous flow of natural gas, cumulative flow and other auxiliary functions are calculated by the flow calculation software. This way is a traditional automatic metering mode, the disadvantage of collection, transmission as analog signal, anti-interference ability is poor, because of signal conversion problems such as precision measurement accuracy is difficult to improve, and hardware is more complex, intermediate links more, reliability is poor. Can be extended to: Single variable transmitter flow computer industrial control machine, so as to achieve flow calculation and display separate, improve the reliability and visibility of the system.
2.2 Variable transmitter flow calculator (or industrial computer)Using 1 multivariable Intelligent transmitter to detect temperature, pressure, differential pressure at the same time, using Fieldbus system, through the digital signal transmission, into the flow computer (or industrial computer) data acquisition card after the flow calculation software to calculate the natural gas instantaneous flow, cumulative flow and other functions to achieve. In this way, hardware connection simplifies a lot and improves the reliability and measurement accuracy of the system. But because the transmitter only detects the measurement signal does not carry on the data processing, therefore must in the school on time and the flow calculator implement the Union School. The main difference between the flow computer and the industrial control machine is the calculation part. Flow computer is a dedicated curing software to achieve the calculation and data storage, more stable and reliable, more trustworthy; Software computing on industrial control computer is generally self-developed, easy to upgrade software and maintenance, because of the large amount of calculation, especially the multi-channel measurement, the reliability is slightly worse. In order to increase the reliability of the system and intuitive operation interface, this method can also be extended to: Variable transmitter flow computer industrial control machine, that is, traffic flow computer to achieve flow calculation, industrial computer display.
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