About the selection of gas turbine flow meter
The selection of gas turbine flowmeter should be considered from the following aspects:
1, accuracy : Generally speaking, the selection of turbine flowmeter is mainly due to its high precision, but the higher the accuracy of the flowmeter, the more sensitive to changes in the field conditions of use, so the choice of instrument accuracy should be careful, from the economic point of view.
2, flow range: the choice of flow range of the turbine flowmeter has a greater impact on its accuracy and service life, and each caliber of the flowmeter has a certain measurement range, the choice of flowmeter caliber is also determined by the flow range. The principle of selecting the flow range is: the small flow rate in use shall not be lower than the smaller flow rate allowed by the instrument, and the large flow rate in use shall not be higher than the larger flow allowed by the instrument. For discontinuous working occasions where the actual running time of the instrument does not exceed 8 hours per day, 1.3 times the greater flow rate in actual use is selected as the upper limit of the flow range; For continuous work situations where the actual daily operation time of the meter is not less than 8 hours, 1.4 times the greater flow rate in actual use is selected as the upper limit of the flow range. The lower limit flow rate of the instrument is suitable for 0.8 times the actual use of the smaller flow rate.
3, the density of gas: the impact on the gas turbine flowmeter and fluid physical properties is mainly the gas density, which has a greater impact on the instrument coefficient, and is mainly in the low flow area. If the gas density changes frequently, the flow coefficient of the flowmeter should be corrected.
4, pressure loss: try to choose a small pressure loss turbine flowmeter. Because the pressure loss of the fluid through the turbine flow meter is smaller, the energy consumed by the fluid from the input to the output pipeline is less, that is, the total power required will be reduced, which can greatly save energy, reduce transmission costs, and improve utilization.
5, structure type: (1) The internal structure should choose the reverse thrust turbine flowmeter. Because the reverse thrust structure can make the impeller in a floating state within a certain flow range, there is no contact point in the axial direction, and there is no end friction and wear, which can extend the service life of the bearing. (2) According to the type selection of pipeline connection, the flow meter has two ways of horizontal and vertical installation, and the horizontal installation and pipeline connection have flange connection, thread connection and clamp connection. Medium diameter flange connection; Small diameter and high pressure pipes are threaded; Clamp connection is only suitable for low pressure small diameter pipe; Vertical mounting only threaded connections. (3) Selection according to environmental conditions, considering the influence of temperature and humidity. Natural gas metering should choose the intrinsically safe explosion-proof turbine flowmeter.
6, bearings: turbine flow meter bearings generally have tungsten carbide, polytetrafluoroethylene, carbon graphite three types of materials. Natural gas meter bearings should be made of tungsten carbide.
