Method and arrangement for the contactless inspection of moving electrically conductive substances

Abstract

The invention relates to a method and arrangement for the contactless determination of conductivity-influencing properties and their spatial distribution over the entire cross section of an electrically conductive substance (O1) moving in a primary magnetic field (B). The substance (O1) may be a liquid or a solid. A simultaneous measurement of a number of mechanical state parameters of the magnetic system (03) is performed (three-dimensional components of the force and the torque), said parameters being variable by the effect of a secondary field on the magnetic system (03), the secondary field being produced on the basis of eddy currents induced in the substance (01) by the primary field (B). To determine the spatial distribution of the property that is sought, the primary field is changed in intensity or form a number times and a measurement of the state parameters is carried out for each change. The determination of the properties sought or their distribution takes place by solving an inverse problem using the method of least squares.

Description

technical field [0001] The invention relates to a method and a device for the contactless determination of properties of electrically conductive moving substances, which may be solid or liquid. In the preferred case of investigations of liquid substances, these substances are considered as moving substances while flowing through lines, channels or similar guidance aids. The invention also relates to a method and a device for the contactless determination of the spatial distribution of the properties of these substances, such as the flow velocity and the conductivity of the substances. The invention is particularly suitable for flow measurement and flow measurement in the field of metallurgy, and also for non-destructive material detection tasks. The device according to the invention is also referred to hereinafter as a Lorentz force flowmeter. Background technique [0002] Precise measurement of flow velocity, flux and other properties (those affecting electrical conductiv...

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Problems solved by technology

[0004] However, this known measurement method has three distinct disadvantages

First, due to its limited sensitivity, it cannot measure flow velocity in very slow-flowing or poorly conductive substances (such as molten glass)

Second, in environments subject to strong electromagnetic interference, the measurement accuracy of the system is strongly limited, since the magnetic field sensor is already affected by the smallest induced fluctuations of the magnetic field due to its small spatial extension

Thirdly, the measurement sensitivity of this method, which is characterized by the relationship between the primary field and the secondary field, cannot be increased by raising the primary field

Furthermore, the measurement sensitivity of these local sensors decreases as a function of the third power (or even the fourth power in the case of large distances) of the distance to the conductive substance and is therefore insufficient for a large number of applications.

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