UN DEBITMETRE COMPORTANT UN ARRANGEMENT D'AIMANT ET D'ELECTRODE DE DETECTION A CAPACITANCE CONSTANTE ENTRE LES ELECTRODES DE DETECTION

A FLOWMETER HAVING A MAGNET AND DETECTION ELECTRODE ARRANGEMENT WITH CONSTANT CAPACITANCE BETWEEN DETECTION ELECTRODES

Abrégé anglais

The present disclosure relates to a flowmeter comprising: an upper magnet and
a lower
magnet arranged respectively at the upper side and the lower side of the outer
wall of a
measurement tube; a left detection electrode and a right detection electrode
installed
respectively at the left side and the right side of the outer wall of the
measurement tube;
a signal processing circuit connected to the left detection electrode and the
right
detection electrode; a left screen electrode and a left screen ring arranged
outside the
left detection electrode, and a right screen electrode and a right screen ring
arranged
outside the right detection electrode. The flowmeter provided by embodiments
of the
present disclosure has low power consumption, small nonlinearity, strong
interference
resistance, and good applicability.

Revendications

WHAT IS CLAIMED IS:
1. A flowmeter, characterized by comprising:
an upper magnet (1) and a lower magnet (2) arranged respectively at the upper
side and the lower side of the outer wall of a measurement tube;
a left detection electrode (3) and a right detection electrode (4) installed
respectively at the left side and the right side of the outer wall of the
measurement tube,
both the left detection electrode (3) and the right detection electrode (4)
being
connected to a signal processing circuit;
a left screen electrode (5) and a left screen ring (7) arranged outside the
left
detection electrode (3), and a right screen electrode (6) and a right screen
ring (8)
arranged outside the right detection electrode (4),
wherein both the left detection electrode (3) and the right detection
electrode (4)
have an elliptical shape to form a constant capacitance.
2. The flowmeter according to claim 1, characterized in that both the upper
magnet (1) and the lower magnet (2) are permanent magnets to provide a
constant
magnetic field.
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Description

CA 02843049 2014-02-17
FLOWMETER
TECHNICAL FIELD
The present disclosure relates to the field of measurement of fluid flow, and
in particular,
to a flowmeter for measuring fluid flow with high precision.
BACKGROUND
The measurement of fluid flow plays a very important role in the field of
industrial
process control. An electromagnetic flowmeter is a type of measurement
equipment for
measuring the flow in volume of a conductive liquid according to Faraday's law
of
electromagnetic induction, and is constituted of a sensor directly contacting
the fluid to
be measured and a converter. A magnetic field is applied to two sides of the
measurement tube of the electromagnetic flowmeter, and the medium to be
measured
cuts the lines of magnetic force when flowing through the measurement tube to
generate induced electromotive force at the detection electrodes at the
outside wall of
the measurement tube. The magnitude of the induced electromotive force is
proportional to the average flow speed of the fluid. Thereby the flow of the
fluid can be
measured.
The electromagnetic flowmeter in the prior art adopts a manner of exciting
coils to
generate a magnetic field, which has a complicated structure and the assembly
of
which is difficult. In addition, the size of the device itself is large.
Therefore, an object of the present disclosure is to design an electromagnetic
flowmeter which has a simple structure, low power consumption, and small
nonlinearity
and the assembly of which is easy.
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CA 02843049 2014-02-17
SUMMARY OF THE DISCLOSURE
In view of the above, an object of the present disclosure is to provide an
electromagnetic flowmeter with permanent magnets and capacitance, which has
advantages of low power consumption, small nonlinearity, strong interference
resistance, and good applicability.
In order achieve the above object, the present disclosure adopts the following
solutions.
A first aspect of the present disclosure provides a flowmeter, comprising:
an upper magnet (1) and a lower magnet (2) arranged respectively at the upper
side and the lower side of the outer wall of a measurement tube;
a left detection electrode (3) and a right detection electrode (4) installed
respectively at the left side and the right side of the outer wall of the
measurement tube,
both the left detection electrode (3) and the right detection electrode (4)
being
connected to a signal processing circuit;
a left screen electrode (5) and a left screen ring (7) arranged outside the
left
detection electrode (3), and a right screen electrode (6) and a right screen
ring (8)
arranged outside the right detection electrode (4),
wherein both the left detection electrode (3) and the right detection
electrode (4)
have an elliptical shape to form a constant capacitance.
According to a flowmeter with permanent magnets and capacitance in a
preferable
embodiment of the present disclosure, both the upper magnet (1) and the lower
magnet
(2) are permanent magnets to provide a constant magnetic field.
(1) The present disclosure adopts permanent magnets to provide a constant
magnetic
field; therefore, the exciting circuit is not needed, and the device has a
simple
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CA 02843049 2014-02-17
structure and low power consumption and is suitable for a scenario of power
supplying with two power lines.
(2) The present disclosure adopts detection electrodes with an elliptical
shape to make
the capacitance between the detection electrodes as constant as possible and
thus
to ensure the uniformity of the electric field which reduces the nonlinearity
and the
interference of granular noise and improves the interference resistance. The
present disclosure can be widely applied to the flow measurement of various
liquid-
solid two-phase fluids such as slurry, paper pulp, etc.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a structural diagram of a flowmeter provided by an embodiment of the
present disclosure;
Fig. 2 is a schematic diagram of the detection electrodes in a flowmeter
provided
by an embodiment of the present disclosure;
Fig. 3 is a front view of a flowmeter provided by an embodiment of the present
disclosure; and
Fig. 4 is a schematic diagram of electric field distribution in a flowmeter
provided
by an embodiment of the present disclosure.
DETAILED DESCRIPTION
The solutions of the present disclosure will be further described in detail in
the following
with reference to the drawings and embodiments.
In the following, the embodiments of the present disclosure will be further
described in
detail in connection with the drawings.
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CA 02843049 2014-02-17
As shown in Fig. 1, an embodiment of the present disclosure provides a
flowmeter as
shown in the figures. The flowmeter comprises: an upper magnet 1 and a lower
magnet 2 arranged respectively at the upper side and the lower side of the
outer wall of
As shown in Fig. 2, both the left detection electrodes 3 and the right
detection electrode
pate capacitor, the capacitance C is proportional to the area of the electrode
plates of
the capacitor, and inversely proportional to the distance between the
electrode plates.
As shown in Fig. 4, the two electrodes are symmetrical with respect to the
center, and
the distance at the upper part decreases gradually. Therefore, when designing
the
flows in the measurement tube, the fluid cuts the lines of magnetic force to
generate
induced electromotive force whose magnitude is proportional to the average
flow speed
of the fluid. The left detection electrode 3 and the right detection electrode
4 installed
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CA 02843049 2014-02-17
at the outer wall of the measurement tube are perpendicular to the upper
magnet 1 and
the lower magnet 2. The left detection electrode 3 and the right detection
electrode 4
form a capacitance with the fluid and the wall of the measurement tube as the
medium.
It is possible to obtain a signal related to the average flow speed of the
fluid by
detecting the change of the capacitance between the left and right detection
electrodes,
and thus achieve the flow measurement of the fluid.
The above embodiments of the present disclosure can achieve the following
advantages and benefits:
(1) The present disclosure adopts permanent magnets to provide a constant
magnetic
field; therefore, the exciting circuit is not needed, and the device has a
simple
structure and low power consumption and is suitable for a scenario of power
supplying with two power lines.
(2) The present disclosure adopts detection electrodes with a shape of an
ellipse to
make the capacitance between the detection electrodes as constant as possible
and thus to ensure the uniformity of the electric field which reduces the
nonlinearity
and the interference of granular noise and improves the interference
resistance.
The present disclosure can be widely applied to the flow measurement of
various
liquid-solid two-phase fluids such as slurry, paper pulp, etc.
The above specific implementation provides a further detailed description of
the object,
the technical solutions and the technical benefits of the present disclosure.
It is
understood that the above description is only specific embodiments of the
present
disclosure and is not intended to limit the protection scope of the present
disclosure.
Any modification, equivalent replacement, enhancement or the like within the
principle
of the present disclosure should all be contained within the protection scope
of the
present disclosure.
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Dessin représentatif