Investigation of Differential Pressure Flowmeters
Accuracy in Pulsating Flows
Roman Fedoryshyn , Fedir Matiko, Ihor Kostyk, Yevhen Pistun
Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013, Ukraine
Received: November 16, 2015. Revised: March 09, 2016. Accepted: December 23, 2016
© 2016, Fedoryshyn R., Matiko F., Kostyk I., Pistun Y. Published by Lviv Polytechnic National University
Abstract
This work deals with the investigation of influence of flow pulsation on the accuracy of gas flowrate and volume measurement by means of the differential pressure flowmeters. Experimental studies of the step response curves of an impulse line with a pressure transducer (PT) were carried out with application of a high-frequency analog-to-digital converter of the pressure signal in the PT chamber. Mathematical model of an impulse line with a PT was built. This model provides simulation and investigation of the transient processes with high accuracy. The influence of the impulse line design (length, diameter) on the step response curves and on the frequency response curves as well as on the resonant frequency of the oscillating system (an impulse line with a PT chamber) was studied. The systematic errors of flowrate and volume measurement due to the resonance in the impulse lines which was caused by flow pulsation were simulated and studied for an acting differential pressure natural gas metering system. On the basis of the calculation results, it was defined that amplification of the amplitude of the oscillating signal of the differential pressure due to the resonance may lead to a negative systematic error of gas volume measurement. The systematic errors of gas flowrate and volume measurement caused by the flow pulsation can be reduced by choosing the correct design of the impulse lines in order to avoid the resonance.
Keywords: flowmeter; flow pulsation; measurement; pressure transducer; natural gas.
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