Orifice plate flowmeter and gas ultrasonic flowmeter in the application of natural gas

Case introduction

Application of orifice plate flowmeter and gas ultrasonic flowmeter in natural gas

1. Range Orifice plate flowmeter has a narrow range (about 3:1 to 4:1). Although in recent years, Measures have been taken from many aspects to broaden its scope, such as using wide-range differential pressure transmitters, using multiple differential pressure transmitters in parallel, using replaceable orifice plate throttling devices and intelligent flow indicators, etc., but with gas ultrasonic The flow meter is inferior in comparison. The range of gas ultrasonic flowmeter can reach 40:1 (dn150) to 160:l (dn75o). In actual use, the lower limit of the measurable flow rate (flow rate) of the flowmeter is a more important indicator. my country's large-diameter gas pipeline system Generally operating in a low flow rate range (the upper limit of the flow rate is only 5 resistance, or lower) makes flow meter selection difficult. Gas ultrasonic flowmeter lower limit flow rate deviation. According to the data, in a natural gas transmission and distribution metering station, a metering station that uses an orifice flowmeter as a measuring instrument needs to set up four dn400mm pipelines to meet the range requirements. If a gas ultrasonic flowmeter is used, only Set up two dn600mm pipelines or one dn700 pipeline, so that the use of gas ultrasonic flow meters can save 10-40% of one-time investment, save 50-75% of floor space, and have higher accuracy, more stable operation and less maintenance.

2. Pressure loss orifice flowmeter is famous for its large pressure loss, while gas ultrasonic flowmeter is an instrument with no pressure loss (only equivalent to a section of pipe). For large diameters, this point is very important. It can save energy consumption or be suitable for Measurement of low static pressure gas piping systems.

3. Instrument cost: As the diameter of the orifice plate flowmeter increases, the cost of the detection parts and installation costs increase significantly. However, the relationship between the manufacturing cost of the detection parts of the gas ultrasonic flowmeter and the diameter is only equivalent to the increase in the value of the pipeline, so it It is an instrument especially suitable for large diameters.

4. Use and maintenance The orifice flow meter consists of 3 parts: throttling device, differential pressure transmitter and flow indicator. Under the harsh working conditions on site, the throttling device, differential pressure transmitter and the connected pressure pipeline are the focus of use and maintenance. In order to frequently check the quality of the orifice plate, natural gas transmission and distribution metering stations often add bypass pipes or use The expensive replaceable orifice plate throttling device increases the cost of the instrument and its auxiliary equipment, as well as the maintenance workload. The gas ultrasonic flowmeter detection part is relatively strong and requires less maintenance work. It can even be made into a plug-in probe, which can be taken out for maintenance without continuous flow.

We will make some comparisons between the application of gas ultrasonic flow meters and orifice flow meters in the natural gas industry. From the above, it can be seen that gas ultrasonic flow meters are undoubtedly more accurate in terms of large-diameter measurement, especially in raw materials. In terms of gas measurement, it is possible to solve the problems that the orifice flowmeter has not been able to solve for many years. At present, work in this area has been initially introduced. We should also see that the orifice flowmeter has been developed for decades to hundreds of years, and all flow workers have Huge theoretical and practical work has been done on it, and a wealth of experience has been obtained. In contrast, gas ultrasonic flowmeters have only just emerged and need to mature through practice. As for small and medium diameters, more work needs to be done.