Patent ID: 7412903

Claim:
A method for measuring a physical, measured quantity, of a mixture flowing in a pipeline, by means of an inline measuring device, including a measurement transducer of the vibration-type, and a measuring device electronics electrically coupled with said measurement transducer, said mixture consisting of at least one majority mixture component and at least one minority mixture component, said method comprising steps of: causing the mixture to be measured to flow through at least one measuring tube of the measurement transducer, with the measuring tube being in communication with the pipeline; feeding an excitation current into an exciter arrangement mechanically coupled with the measuring tube conducting the mixture, for causing the measuring tube to execute mechanical oscillations, and driving said measurement tube to oscillate with at least one instantaneous resonance frequency of a first natural eigenmode, and inducing Coriolis forces within the mixture flowing through the vibrating measurement tube; sensing vibrations of the measuring tube and producing at least one oscillation measurement signal representing oscillations of the vibrating measuring tube; estimating from the excitation current and from said at least one oscillation measurement signal a Coriolis coupling coefficient, said Coriolis coupling coefficient corresponding with an instantaneous coupling between said first natural eigenmode currently driven by the exciter arrangement and a second natural eigenmode of the measurement tube, in said second eigenmode the measurement tube having an eigenform corresponding with a mode of vibration caused by said Coriolis forces induced in the mixture, and said Coriolis coupling coefficient varying in time due to a variation of a concentration of at least one of said majority and said minority components of the mixture; and using said at least one oscillation measurement signal and/or the excitation current, together with said Coriolis coupling coefficient, for producing a measured value representing the physical, measured quantity to be measured.