Ultrasonic gas flow meter is used to measure the flow of gas. It is a flow meter that measures the flow rate of gas using the principle that the propagation speed of ultrasonic waves changes with the change of flow rate. The resolution has reached a resolution of 1mm/s so far, and it has been able to measure small flows and bidirectional gas flow. In engineering applications and international natural gas trade, there is a great trend to replace traditional instruments.
The ultrasonic gas flowmeter consists of a flow transducer and a controller. The standard segmented ultrasonic gas flowmeter usually has a sleeve with a ball valve for the installation and overhaul of the transducer. High-accuracy gas flowmeters typically employ a parallel symmetry arrangement and a cross-reflection arrangement. It is necessary to consider the problem of automatically eliminating the influence of the air vortex. Transducer installations are plug-in type, the operating frequency is generally selected between 60 ~ 120khz. Explosion protection should be considered for combustible gases. The working principle of the controller is shown in Figure 6.20. The transducer alternately emits and receives acoustic pulses, typically 20 to 60 times per second. After amplification, calculation, and compensation, the signal outputs digital and analog signals.
ultrasonic gas meter's advantage
1, High accuracy, good repeatability, strong anti-interference ability.
2, Accurately measure pulsed flow.
3, Bidirectional flow measurement.
4, Wide range ratio.
5, No moving parts, no pressure loss, low maintenance.
6, Transducer replacement can be performed under pressure.
7, Dry calibration can be performed at the site of use.
Ultrasonic gas flowmeters are basically divided into two categories based on their actual use: one for gas flow measurement and the other for gas flow calibration devices or trade measurements. The former is usually installed at the site where the gas pipe is used for drilling; the latter are all standard pipe segments. Specific use: gas trade handover measurement; check the standard table of general gas flow meter. The gas measured by an ultrasonic gas flow meter is basically two kinds of natural gas and air. Natural gas is a mixture of gases, the main component is methane (more than 95%), ethane, propane, n2, co2 and other gases. The sound speed is about 420m/s at 15°C. The speed of sound is related to composition, pressure, density, and temperature, so the compression factor and temperature pressure correction of different components must be considered. The position of ultrasonic gas flow meter must have enough straight pipe sections to ensure the accuracy of measurement. Particles and droplets in the pipeline, if attached to the transducer's radiation surface, will affect the propagation of the acoustic pulse, and even make the flowmeter inoperable.