How to choose the gas turbine flow meter correctly

With the advancement of the "West-East Gas Pipeline" project, the use of natural gas has become more and more extensive. In the process of using natural gas, gas turbine flow meters have become an indispensable measuring instrument. The technical personnel of Jiangsu Aiketei Instrument Co., Ltd. introduce the problems that should be noticed in the selection, use, and maintenance of gas turbine flowmeters as follows:

First, the selection of gas turbine flow meter selection should be considered from the following aspects:

1. Accuracy level: In general, the turbine flowmeter is mainly used for high accuracy, but the higher the accuracy of the flowmeter is, the more sensitive it is to changes in the conditions of use on the site. Therefore, the accuracy of the meter must be selected. Carefulness should be considered from the economic point of view. For large-diameter gas pipelines trade settlement instruments, it is cost-effective to invest more in the instrument, but for medium-precision levels when the transport volume is small.

2, flow range: Turbine flow meter flow range of the choice of its accuracy and useful life has a greater impact, and each caliber of the flow meter has a certain range of measurement, flow meter diameter is also selected by the flow range . The principle of selecting the flow range is that the minimum flow rate during use must not be lower than the minimum flow rate that the instrument allows to measure. The maximum flow rate during use must not be higher than the maximum flow rate that the instrument can measure. For intermittent work situations where the daily meter actual running time does not exceed 8 hours, select 1.3 times of the maximum flow for actual use as the upper limit of the flow range; for continuous working situations where the daily meter actual running time is not less than 8 hours, select the actual Use 1.4 times the maximum flow rate as the upper limit of the flow range. The lower limit flow rate of the instrument is 0.8 times the minimum flow rate actually used.

3. Density of Gas: For gas turbine flowmeters, the physical properties of the fluid are mainly the gas density, which has a large influence on the meter coefficient, and is mainly in the low flow area. If the gas density changes frequently, corrective measures must be taken for the flow coefficient of the flowmeter.

4, pressure loss: try to use a small turbine pressure loss. Because the smaller the pressure loss of the fluid passing through the turbine flow meter, the less energy the fluid consumes from the input to the output pipe, ie, the total power required will be reduced, which can greatly save energy, reduce transportation costs, and increase utilization. .

It has been tried, the main component that affects the pressure loss is the front flow deflector of the turbine flow meter, the pressure loss of the former turbine flow meter is compared with the front flow deflector of the selected cone compared with the front flow deflector using the semi-ellipsoid. Can be greatly reduced.

5, structural type: (1) internal structure should use reverse turbine turbine flowmeter. Because the reverse push type structure can make the impeller in a floating state within a certain flow range, there is no contact point in the axial direction, and no end surface friction and wear can prolong the service life of the bearing. (2) According to the selection of pipeline connection, the flowmeter has two methods of horizontal and vertical installation. The horizontal installation and pipeline connection are flanged connection, screw connection and clamping connection. The medium caliber is flanged; small diameter and high pressure piping are threaded; clamped connections are only suitable for low and medium diameters; vertical mounting is threaded only. (3) According to environmental conditions, consider the influence of temperature and humidity. Natural gas metering should choose intrinsically safe explosion-proof turbine flowmeters.

6, Bearing: Turbine flowmeter bearing generally tungsten carbide, PTFE, carbon graphite three materials. Natural gas metering bearings should use tungsten carbide materials.

The above are the main aspects to consider when selecting a model. Due to the wide variety of types of turbine flowmeters, especially the quality of products from different manufacturing plants, the technical standards of the manufacturer and its products should be collected as much as possible when selecting a type of turbine.

Second, use and maintenance In order to ensure the long-term normal operation of gas turbine flowmeter, must always check the flowmeter's operating conditions, make maintenance work, and find problems in a timely manner.

1. Before the turbine flowmeter is put into operation, it is necessary to set the meter factor, check it carefully, and confirm that the flowmeter can be connected without errors and be well grounded before sending power.

2. Regularly clean, check and recalibrate the flowmeter. The flow meter with lubricant or cleaning fluid injection port should be regularly injected with lubricating oil or cleaning fluid in order to maintain good impeller operation.

3, monitor shows the status of the instrument, the assessment shows the meter readings, abnormalities should be checked in time.

4, keep the filter open. The filter is blocked by impurities, and can be judged from the increase in the reading of the pressure gauge at the entrance and exit of the filter, and the blockage is eliminated in time. Otherwise, the flow rate will be seriously reduced.

5, for large-flow trade settlement measurement, in order to ensure the accuracy of the flowmeter, the flowmeter must always check. The site should be equipped with on-line calibration equipment, or equipped with a mobile calibration device. Although the one-time investment is large, it is worthwhile considering the long-term economic benefits.