Talk about how to select gas turbine flowmeter correctly
Author: PhilemonTime: 2020-09-07
The selection of gas turbine flow meters should be considered from the following aspects:
1. Accuracy level: Generally speaking, the choice of turbine flowmeter is mainly based on its high accuracy, but the higher the accuracy of the flowmeter, the more sensitive it is to changes in the field conditions. Therefore, the choice of instrument accuracy Prudence should be considered from an economic point of view. For large-diameter gas pipeline trade settlement instruments, it is cost-effective to invest more in the instruments, but for occasions where the transportation volume is not large, the medium accuracy level can be selected.
2. Flow range: The selection of the flow range of the turbine flowmeter has a greater impact on its accuracy and service life, and each type of flowmeter has a certain measurement range, and the selection of the flowmeter diameter is also determined by the flow range. . The principle of selecting the flow range is: the minimum flow during use shall not be lower than the minimum flow allowed by the instrument, and the maximum flow during use shall not be higher than the maximum flow allowed by the instrument. For intermittent working occasions where the actual operating time of the instrument does not exceed 8 hours per day, select 1.3 times the maximum flow rate in actual use as the upper limit of the flow range; for continuous operating occasions where the actual operating time of the instrument is not less than 8 hours per day, select actual 1.4 times the maximum flow rate when in use is the upper limit of the flow rate range. The lower limit flow rate of the instrument is 0.8 times the minimum flow rate actually used.
3. Gas density: For gas turbine flowmeters, the main influence of fluid physical properties is gas density, which has a greater influence on the meter coefficient and is mainly in the low flow area. If the gas density changes frequently, corrective measures should be taken to the flow coefficient of the flowmeter.
4. Pressure loss: Try to choose a turbine flowmeter with a small pressure loss. Because the pressure loss of the fluid through the turbine flowmeter 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 transportation costs, and improve utilization. .
Someone has done an experiment. The main component that affects the pressure loss is the front deflector of the turbine flowmeter. Compared with the cone-shaped front deflector, the pressure loss of the former turbine flowmeter is Can be greatly reduced.
5. Structure type: (1) The internal structure should use 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 face friction and wear, which can prolong the service life of the bearing. (2) According to the pipeline connection mode selection, the flowmeter has two modes of horizontal and vertical installation. The horizontal installation and the pipeline connection have flange connection, thread connection and clamp connection. Flange connection is used for medium diameter; threaded connection for small diameter and high-pressure pipes; clamp connection is only suitable for low-pressure medium and small pipe diameters; vertical installation only has threaded connection. (3) Model selection according to environmental conditions, taking into account the effects of temperature and humidity. Natural gas metering should choose intrinsically safe explosion-proof turbine flowmeter.