Design And Implementation Of The Ultrasonic Gas Wave Flow Measurement System

Ultrasonic gas wave flowmeter has obvious advantages in the field of gas flow measurement because of its high precision,no pressure loss and large range ratio.With the continuous development and expansion of China's clean energy sources such as natural gas,biogas,and coalbed methane,the demand for high-performance gas flow metering devices has become more urgent.At present,almost all ultrasonic gas wave flowmeters with excellent performance on the market need to be imported,and foreign countries still maintain a blocked attitude toward their core technologies.Therefore,it is of great significance to realize the autonomy of ultrasonic gas flowmeter production at an early date.To this end,this paper takes the ultrasonic gas wave flow measurement system as the research target.An ultrasonic gas flow measuring system based on time difference method is developed through the in-depth study of the relevant theory of gas flow measurement technology,according to the characteristics of ultrasonic signal,and combined with the actual demand.The system possesses data acquisition of such three parameters as flow,temperature and pressure,real-time display of measurement results,data storage,data remote communication and other functions.The main research contents are as follows:Through the review of a large number of literatures and product research in the gas flow market,the research background and development status of ultrasonic gas flow measurement technology are discussed.Starting from the principle,the related theories of ultrasonic gas flow measurement technology are deeply studied,and the measurement principle,time measurement method and related scheme of the transducer are determined.In view of the accurate measurement of ultrasonic propagation time,this paper proposes to use the performance advantages of high-precision time measurement chip TDC-GP22 to ensure the accuracy of time measurement;design an efficient excitation signal drive circuit to improve the output power of the transmitted signal;design a reasonable receiving circuit to effectively realize the extraction of echo signals and the suppression of noise interference;at the same time,the automatic gain control circuit is adopted in the received signal to ensure that the received signal is not easily affected by the change of the measurement environment,and provides a strong guarantee for the accuracy of time measurement;moreover,functional modules such as temperature compensation circuit,data display,data storage,data upload and power management are also designed.In the end,the design of a complete ultrasonic gas flow measurement hardware system is completed.According to the relevant requirements of the hardware circuit,this paper completed the running software program of the ultrasonic gas flow collecting circuit and the control circuit,and developed a friendly human-computer interaction module by using the LCD segment code screen and the infrared remote controller.After the system was developed,the performance calibration and function verification of the developed measurement system were carried out.The three parameters of the critical flow nozzle,digital pressure gauge and constant temperature water tank were tested by flow,pressure and temperature.The verification results show that the flow parameters meet the accuracy standard of 1.5,the pressure parameters meet the accuracy of 0.5 and the temperature parameters meet the accuracy of grade B;therefore,the system performance is excellent,reaching a high level of the mono ultrasonic gas flowmeter.