Method for measuring flow of conductive fluid in non-full pipe by using electromagnetic flow meter

Abstract

The invention discloses a method for measuring flow of conductive fluid in a non-full pipe by using an electromagnetic flow meter. The adopted flow meter is provided with at least three pairs of measuring electrodes, a grounding electrode, a coil structure for generating a magnetic field and a pressure sensor; a plurality of pairs of electrodes on the inner wall of the measured pipe ensure that each pair of electrodes is contacted with the fluid under different fluid levels H; and the measuring electrode pair is reasonably selected according to the different fluid levels so as to ensure the measurement accuracy. The measurement method is characterized in that: different pairs of electrodes are selected for measuring the flow rate under the different fluid levels, a fluid level signal H is obtained by using a pressure signal P of the pressure sensor so as to overcome measurement errors of the conductive fluids of different categories due to different conductivities and dielectric constants, the equivalent sectional area S of the fluid in the non-full pipe is calculated through the fluid level signal, the signal E of an induced electromotive force measured by the flow sensor is converted into a flow rate signal V, and the corresponding flow Q of the fluid in the non-full pipe can be obtained by integrating the equivalent sectional area S and the flow rate signal.

Description

technical field [0001] The invention relates to a method for measuring the flow of a conductive fluid in a partially filled pipe with an electromagnetic flowmeter. Background technique [0002] Ordinary electromagnetic flowmeters use a sensor with a constant cross-sectional area to measure the average flow velocity to obtain the flow rate. The cross-sectional area of ​​the fluid in the partially filled pipe changes, and the flow measurement must not only measure the average flow velocity flowing through the sensor, but also measure the cross-sectional area of ​​the fluid flowing through the sensor. That is to say, the flow measurement of the partially filled electromagnetic flowmeter requires at least two variables of flow velocity V and liquid level H. [0003] The measurement methods of the partial pipe electromagnetic flowmeter mainly include the method of using a large-area electrode sensor with a curved plate with the center of the pipe biased towards the bottom, the l...

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Problems solved by technology

[0004] For the case where the single conductive fluid remains unchanged, that is, when the conductivity of the fluid remains unchanged, capacitive and double-excitation types can realize the measurement of a non-full tube, but when the conductivity and fluid characteristics of the fluid change When the measurement accuracy will be greatly affected

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