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Characteristics of natural gas electromagnetic flowmeter measurement and its requirements for instruments

The characteristics of natural gas electromagnetic flowmeter measurement and its requirements for instruments: natural gas as a primary energy, the proportion of the world's primary energy structure has increased year by year. Developed countries generally have reached 30%-40%, so the amount involved in the measurement of natural gas trade transfer is huge, which has attracted extensive attention in the world. In order to ensure the fair and reasonable trade measurement of natural gas production and utilization enterprises, and to safeguard the legitimate rights and interests of both sides of trade, Europe first formulated EN 1776: 1998 "Basic Requirements for Natural Gas Measurement Systems". On the basis of this standard, China has also formulated the corresponding standard GBlT 186 03 2001 "Technical Requirements for Natural Gas Metering System".
Natural gas metering systems have the following main features and basic requirements.
(1) Explosion-proof requirements The fluid is flammable and explosive. Possible hazardous areas should be classified according to GB 3836.1. In the hazardous area, the selection and installation of any instruments and electrical equipment should comply with the provisions of GB 3836.
(2) Uninterrupted gas supply requirements In order to ensure continuous gas transmission, the gas supply should not be interrupted due to maintenance of the meter, and the metering station and the metering circuit should be bypassed. For important large-flow users, parallel double metering circuits are recommended. The bypass valve and the parallel dual metering circuit upstream valve (or downstream valve) should be selected to close the shut-off valve with good performance, durability and leak detection device to avoid non-metering loss.
(3) Diversity of working conditions Natural gas needs to be metered from collection, treatment, transportation to distribution. The fluid in the collection process is dirty, and the gas is even mixed with solid phase. Different gas wells have large differences in pressure. The fluid pressure in the transport section is also high, but when it is distributed to the end user, the pressure may drop very low. Therefore, the flow measurement of different links should understand the fluid conditions and specific conditions, and cannot be generalized.

(4) Different accuracy requirements Natural gas measurement is a large-scale energy measurement, and the larger the flow value, the greater the settlement amount involved. The price of the configured flow meter is related to the accuracy. The higher the accuracy, the higher the price. The metering system with relatively small measurement value generally cannot afford the high-accuracy meter with much higher price. Therefore, only Reduce the requirements, but still meet the requirements of the relevant standards. Table 2.1 lists the different grades of vortex flowmeter metering systems and instruments equipped with Weinan. Table 2.2 shows the accuracy requirements of the metering system for different grades of metering systems.
1 When the supply and exhaust gas are handed over with energy flow, a matching project is required.
(5) Different output types and units of measurement for metering systems. Metering systems consist of natural gas flow meters and different parameters.
The measured transmitter, the flow calculation, and the conversion device that determines the output of each of the outputs. According to the composition and needs of the system, the pressure gauge related to the calculation of gas and steam quality should be output, and the accuracy should not be lower than 1.0%.
When the measuring instrument is a measuring device or system consisting of a sensor (transmitter) or a secondary instrument, the accuracy given in Table 2.3 shall be the accuracy of the device or system (when the device or system does not clearly give its accuracy) The accuracy of the available sensors and the secondary instrument according to the error synthesis method when the synthetic energy is used as the production raw material, the accuracy of the measuring instrument should meet the corresponding production process requirements.
The performance of the electromagnetic flowmeter must meet the corresponding production process characteristics and the requirements of the use environment, such as corrosion resistance, high temperature resistance, vibration resistance, dust prevention, and electromagnetic interference prevention.

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