Flow sensor, flow measurement arrangement and flow measurement method provided with it

摘要

Flow sensor (22) for measuring a flow of an electrically conductive fluid (20) through a fluid line (18), comprising: - A magnetic field generating device (26) for generating an excitation magnetic field (10) with a polarity that changes periodically at a frequency of at least 1 kHz, preferably 5 kHz, more preferably 10 kHz, the excitation magnetic field (10) being such that due to its interaction with the fluid (20) results in an effective magnetic field (44), which at a first measuring location (33) has a first magnetic field amplitude (46) that is directly proportional to the flow velocity of the fluid (20) in the direction of flow, or that at a first measuring location ( 33) has a first magnetic field amplitude (46) and at a second measuring point (35) a second magnetic field amplitude (48), the difference of which is directly proportional to the flow velocity of the fluid (20) in the flow direction; - A magnetic field detection device (30) for detecting the effective magnetic field (44) at a first measuring location (33) or at a first and second measuring location (33, 35); and - A control unit (52) for controlling the magnetic field generating device (26) and for determining the flow rate of the fluid (20) through the fluid line (18) on the basis of the signal of the magnetic field detection device (30).