Yamatake Corporation

Azbil Corporation

Tomoshige Yamamoto

Kenji Yao

Yoshio Yamazaki

Daisuke Akita

An electromagnetic flowmeter comprises a measuring pipe through which fluid to be measured flows, an electrode provided therein, an exciting unit, a signal line, a signal conversion unit that extracts a &#x2202;A/&#x2202;t component that results from a change in the magnetic field from a resultant electromotive force of an electromotive force of the &#x2202;A/&#x2202;t component; and an electromotive force of a v&#xd7;B component that results from a flow speed of the fluid, wherein the resultant electromotive force is detected by the electrode and the signal line; and a flow rate output unit that eliminates, based on the extracted &#x2202;A/&#x2202;t component, a variation factor as to a span that is a coefficient applied to a magnitude V of a flow speed of the v&#xd7;B component in the resultant electromotive force so as to calculate a flow rate of the fluid.

Electromagnetic flowmeter with automatic span correction

An electromagnetic flowmeter includes a measuring tube, electrodes, an exciting coil for applying, to a fluid, a time-changing magnetic field asymmetrical with respect to a plane PLN, a signal conversion unit which extracts a &#x2202;A/&#x2202;t component, irrelevant to a fluid flow velocity, from a resultant electromotive force of an electromotive force based on the &#x2202;A/&#x2202;t component and an electromotive force based on a v&#xd7;B component originating from the flow velocity of the fluid, a flow rate output unit which removes a variation factor for a span as a coefficient applied to a magnitude V of a flow velocity of the v&#xd7;B component in the resultant electromotive force, based on the extracted &#x2202;A/&#x2202;t component, and calculates a flow rate of the fluid from a result obtained by removing the variation factor, and signal lines inclined with respect to a direction of the magnetic field in parallel with the plane PLN.

Electromagnetic flowmeter

A state detection device which detects parameters includes a measuring pipe, electrodes, an exciting coil that applies a magnetic field to the fluid, signal lines arranged at angle to the magnetic field such that an electromotive force is generated due to a change with passage of time in the magnetic field, and a state quantifying unit for extracting a &#x2202;A/&#x2202;t component from resultant electromotive forces that are detected at the electrodes and the signal lines and are composed of an electromotive force of the &#x2202;A/&#x2202;t component irrelevant to a flow velocity of the fluid and resulting from a change with passage of time in the magnetic field and an electromotive force of a v&#xd7;B component relevant to the flow velocity of the fluid, and extracts a variation factor relevant to the parameter from the &#x2202;A/&#x2202;t component to quantify the parameter based on the variation factor.

State detection device

An electromagnetic flowmeter includes a measuring tube () through which a fluid to be measured flows, electrodes () which are placed in this measuring tube and detect an electromotive force generated by a magnetic field applied to the fluid and the flow of the fluid, an exciting coil () and power supply unit () which apply a time-changing magnetic field to the fluid, a signal conversion unit () which extracts a &#x2202;A/&#x2202;t component from the resultant electromotive force of the electromotive force based on the &#x2202;A/&#x2202;t component irrelevant to the flow velocity of the fluid and the electromotive force based on a v&#xd7;B component originating from the flow velocity of the fluid, which are detected by the electrodes (), and a flow rate output unit () which extracts only the v&#xd7;B component by removing the extracted &#x2202;A/&#x2202;t component from the resultant electromotive force, and calculates the flow rate of the fluid based on the v&#xd7;B component.

An exciting unit, applies, to a fluid, a time-changing magnetic field asymmetrical to a plane (PLN). An electrode is placed on the plane in a measuring tube, and detects a resultant electromotive force of an electromotive force based on &#x2202;A/&#x2202;t component (A: vector potential, t: time) irrelevant to a flow velocity of the fluid and an electromotive force based on a v&#xd7;B component originating from the flow velocity of the fluid. A state quantifying unit extracts the &#x2202;A/&#x2202;t component and a variation factor dependent on a parameter to be detected, and quantifies the parameter on the basis of the variation factor. The characteristic and state of the fluid and the state in the measuring tube can be detected regardless of the flow rate of the fluid by using the same hardware arrangement as that of an electromagnetic induction type flowmeter.

An electromagnetic flowmeter includes a measuring tube through which a fluid flows, electrodes which detect an electromotive force generated by a magnetic field applied to the fluid. An exciting coil applies, to the fluid, a magnetic field asymmetrical to a plane (PLN) which includes the electrodes and is perpendicular to the axial direction of the measuring tube. A signal conversion unit extracts a &#x2202;A/&#x2202;t component from the resultant electromotive force of the electromotive force. A flow rate output unit removes a variation factor for a span as a coefficient applied to the magnitude of the flow velocity on the basis of the &#x2202;A/&#x2202;t component, and calculates the flow rate of the fluid from the result obtained by removing the variation factor. The exciting coil applies the magnetic fields including the plurality of frequency components to the fluid.

Electromagnetic flowmeter for applying a magnetic field and a plurality of frequency components to a fluid

An electromagnetic flowmeter includes a measuring tube through which a fluid to be measured flows, electrodes which detect an electromotive force generated by a magnetic field applied to the fluid. An exciting coil applies, to the fluid, a time-changing magnetic field asymmetrical to a plane (PLN) which includes the electrodes and is perpendicular to the axial direction of the measuring tube. A signal conversion unit extracts a &#x2202;A/&#x2202;t component from the resultant electromotive force of the electromotive force. A flow rate output unit removes a variation factor for a span as a coefficient applied to the magnitude of the flow velocity on the basis of the &#x2202;A/&#x2202;t component, and calculates the flow rate of the fluid from the result obtained by removing the variation factor.

Electromagnetic flowmeter with measuring tube

An electromagnetic flowmeter includes a measuring tube, an electrode, an exciting unit, a signal conversion unit, and a flow rate calculating unit. The signal conversion unit extracts a &#x2202;A/&#x2202;t component irrelevant to a flow velocity of the fluid and a v&#xd7;B component originating from the flow velocity of the fluid from a resultant electromotive force of an electromotive force &#x2202;A/&#x2202;t, with A, t, v, and B respectively representing a vector potential, a time, a flow velocity, and a magnetic flux density. The flow rate calculating unit extracts a variation component dependent on a parameter from the &#x2202;A/&#x2202;t component, corrects a span which is a coefficient applied to a magnitude V of the flow velocity of the v&#xd7;B component, and calculates the flow rate of the fluid from the v&#xd7;B component whose span is corrected.

When a plane (PLN) which includes electrodes () and is perpendicular to the direction of an axis (PAX) of a measuring pipe () is defined as a boundary in the measuring pipe (), an exciting coil () applies asymmetrical magnetic fields to a fluid to be measured, which flows through the measuring pipe (), on both sides of the plane (PLN) serving as the boundary in the measuring pipe (). A signal conversion unit () obtains the phase difference between an exciting current supplied to the exciting coil () and an interelectrode electromotive force detected by the electrodes (). A flow rate output unit () calculates the flow rate of the fluid on the basis of the phase difference obtained by the signal conversion unit ().

In an electromagnetic flowmeter, a fluid to be measured flows through a measuring pipe. An electrode in the measuring pipe detects an electromotive force generated by a magnetic field applied to the fluid and flow of the fluid. A first exciting coil applies a first magnetic field having a first frequency to the fluid. A second exciting coil applies, to the fluid, a second magnetic field obtained by amplitude-modulating a carrier having the first frequency by a modulated wave having a second frequency. A power supply section supplies an exciting current to the first and second exciting coils. A signal conversion section separates the component of the first frequency from the electromotive force to obtain an amplitude, separates one of the components of sum and difference frequencies of the first and second frequencies from the electromotive force to obtain an amplitude, and obtains an amplitude ratio. A flow rate output section calculates the flow rate of the fluid on the basis of the amplitude ratio.

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Tokyo, Japan

Tomoshige Yamamoto