Calculation and Experimental Study of the Effect of Operational Wear on the Dynamic Properties of a Coriolis Flowmeter

Abstract

The article discusses a patented method for the technical diagnosis of a Coriolis flowmeter at its operation site, using algorithms embedded in the electronics. The method is based on describing the initial state of the Coriolis flowmeter as the ratio of two modal frequencies measured during the operation of the Coriolis flowmeter. Its state can be assessed by comparing the frequency ratio with initial data. To evaluate the effectiveness of the method, the article uses a beam finite element model to study the influence of the local wear of different tube sections on the error in determining the flow rate and the frequency ratio. To this end, each tube in the model is divided into ten sections. The wear of individual sections and some combinations are simulated by varying the internal diameter of the tube sections. In real-world conditions, the Coriolis flowmeter can measure the flow rates of both liquids and gases in a wide range of temperatures. Therefore, calculations are performed for different densities and temperatures of the working medium. The article presents the results of experimental studies into the Coriolis flowmeter. Electrochemical wear was applied to the inner surface of a tube using a special setup. After two rounds of wear, flow errors and frequency ratios were recorded. The authors found that an unacceptable change in the flow error caused by the tube wear can be detected by determining the frequency ratio. The wear of different sections of the tube affects the flow error and the frequency ratio to varying degrees. The diagnostic accuracy can be improved by using the ratio of three pairs of frequencies. The frequency ratios are weakly dependent on temperature.