A Study On The Flowmeter Based On The Theory Of Electromagnetic And Ultrasonic Composites

Electromagnetic flowmeter and ultrasonic flowmeter are widely applied in chemical, pharmaceutical, mining, gas oil and other industrial fields. Under sever environment, it is inconvenient to dismantle the flowmeter after installation, and the pipelines is unable to outage. Flowmeters calibrate only through on-line. This thesis studies on an integrated flow meter composed of an ultrasonic flowmeter and an electromagnetic flowmeter to solve meter calibration problem. Two meters use the same measuring tube to measure real-time fluid flow and compare with each other. The data will be more correct. We can choose a suitable flowmeter under different situations.Ultrasonic transducer assemblies which installed on the fluid part of the electromagnetic flowmeter measurements have certain interference with its measurement. It is needed to conduct after the theoretical study to determine the feasibility before actual research. Details are as follows:(1) Use CFD numerical simulation to study the flow filed in the measurement tube and to determine the proper installation position for transducer inside the pipe.(2) Electromagnetic flowmeter uses low-frequency excitation mode three-valued square wave excitation, which can effectively improve the zero stability. Ultrasonic flowmeter uses the principle of difference method with high accuracy. Software and hardware design systems, software kernel uses u C/OS-II embedded operating system which is more real-time and with high stability.(3) Use RS485 communication technology to read and write two meter parameters. Use 4.3 inch LCD screen as daily display screen.(4) Design mechanical drawings and membrane keypad header. Analyze experimental testing and data after installation is completed.Experimental results for the ultrasonic flowmeter repeatability is better than 0.09%, the measurement error is less than 0.4%, electromagnetic flow meter repeatability better than 0.08%, measurement error is less than 0.4%. These results prove that the installation of ultrasound transducer does not affect the measurement accuracy of electromagnetic flowmeter to meet the desired performance indicators(accuracy class 0.5). The integrated flow EMAT design not only achieves design innovation, but also the final experimental results and theoretical studies have proved that the principle is ideologically feasible.