Study On Flow Measurement Method With Control Valve

This paper proposed a control valve based flow measurement method.This method made use of widely existed control valves in pipeline system. The flowrate can be measured without any other devices which may bring about additionalpressure drop. The method uses control valve’s inhernt characteristic flow curve andpressure drop, caculates out the flow rate.Preliminary study was processed with CFD simulation. A principle of pressuresampling points selection was determined. The upstream pressure sampling pointcould be close to valve while the downstream pressure sampling point is relative farfrom valve. For steady-state flow measurement, satisfied accuracy was acquired, butmeasurement error change regularity was not obtained from the analysis ofsimulation results. For unsteady-state flow measurement, qualitative study of thecharacteristics indicated that rapid valve opening and closing processes results inflow deviation. At the beginning, the flow rate variation is lag behind the opendegree of valve.An experimental water flow measurement system was established, whichconsists of hardware part and software part. The hardware part includs pipeline andconnection, pressure sampling hole, pressure transmitters, valve actuator and so on.The software part includs GUI design, serial communication, multi-threadingtechnology and so on.Both steady-state and unsteady-state research of the control valve based flowmeasurement method was carried out on the established experimental platform. Forpressure sampling points selection, the experimental result is similar to the CFDsimulation result. For steady-state flow measurement, research shows that theaccuracy is of high precision, and discovers that the optimum working conditionsinclude large valve differential pressure and small valve open degree. Imitation ofreal working conditions acquired relative errors of1.13%,3.95%,2.82%corresponding to sine signal, triangular signal and random signal. Above relativeerrors are caculated with an accumulate bucket as reference. Result shows that the accumulated flow measurement is also good.