Design Of Low-power Consumption Electromagnetic Flowmeter

With the advantages of simple sensor structure, no mechanically movingparts, no additional head loss, linear measuring principle, high reliability andaccuracy and ect., electromagnetic flowmeters are widely used in industrial flowmeasurement. With the trend of reducing energy consumption and low carboneconomy construction, the low-power consumption design of electromagneticflowmeter becomes a major concern. New design schemes were proposed in thispaper to improve the sensing principle and the transducer structure ofelectromagnetic flowmeter, and detailed theoretical analysis was given as how toachieve low-power consumption design of electromagnetic flowmeter.Based on the analysis of the measurement principle, a bridge-type flowmeasurement technique based on a Wheatstone bridge network was introduced. Thebasic principle of the Wheatstone bridge network flow measurement technique wassystematically explained. The Wheatstone bridge network flow sensor and themeasurement circuit schematic diagram were designed. A prototype based on theWheatstone bridge network flow measurement technique was tested. The experimentresults have confirmed the feasibility of the proposed design scheme. Further more,as this proposed technology for small flow measurement has the advantages ofsimple structure, low cost and low-power consumption, a measurement systemcombining the Wheatstone bridge network flow measurement technique and thetraditional electromagnetic measurement technique was proposed to improve theconventional design of electromagnetic flowmeter.A new transducer structure was proposed in this paper. The proposed measuringtube has circular cross-section at its inlet and outlet, blended by contraction anddiffusion portions to an intermediate portion of rectangular cross-section. Comparedwith the conventional design of electromagnetic flow transducer with a centeraxisymmetric electric field, the electromagnetic flowmeters with rectangularmeasuring tube and electrodes which average out the electric field do not depend onthe velocity distribution in the pipe. The transducer based on the proposed design canachieve an uniform flow profile, higher sensitivity and low-power consumption. The flow field of measuring tube was simulated by3D modeling and numericalsimulation based on the computational fluid dynamics software FLUENT. Thevelocity distribution and streamline of the reducer were analyzed. The relationshipbetween the rectangular cross-sectional length, width, height and the inlet-outletpressure drop and average velocity of the center profile was established. The mainpoints of pipeline structure design have been summarized. The reference designguidelines have been presented.