CN100375891C - Electromagnetic flow sensor for measuring non-full pipe flow and method for measurement - Google Patents

Abstract

The related EM flow sensor for non-full flow comprises a measuring tube, a couple of long-arc electrodes on the tube wall, and an excitation unit for magnetic field B. the measurement method refers to: on states that the excitation unit works or not, applying electrodes to measure fluid induced potential E and impedance Z under non-full level H; according to corresponding relation, calculating the flow as Q = V*S. This invention is simple and convenient.

Description

Be used to measure the measuring method of non-full pipe flow

Technical field

The present invention relates to a kind of measuring method that is used to measure non-full pipe flow.

Technical background

The traditional electrical magnetic flow transducers is to measure to be full of sensor measuring tube flow rate of fluid V, and the sectional area S of corresponding measuring tube has flow Q=S * V.Must in rate of flow of fluid V, also must measure the liquid level H of non-full pipe flow for the measurement of non-full pipe flow.Existing non full package flow measurement has the method that increases multi-electrode level gauging, electric capacity level gauging, magnetic field conversion level gauging in electromagnetic flow transducer.These methods make the structure of electromagnetic flow transducer and measuring process complicated.

At present, the double-excitation electromagnetic flow technology of patent 200510028473.3 and 200510110182.9 is arranged, make traditional electromagnet flow meter sensor not only can measure rate of flow of fluid V but also can measure the impedance Z of fluid at the electrode two ends.Based on the measuring multiple parameters method and the technology of double-excitation electromagnetic flow technology, make non full package flow measurement can utilize the electrode tip impedance of electromagnet flow meter sensor to measure the liquid level H of partly-filled pipe-flow.For the non-full pipe flow measurement method based on electromagnetic flow transducer provides technological means.

Summary of the invention

The purpose of this invention is to provide a kind of electromagnetic flow transducer and measuring method that is used to measure non-full pipe flow.Its sensor construction is simple, and measuring method is easy and can satisfy the flow measurement of partly-filled pipe-flow.

For achieving the above object, the present invention by the following technical solutions:

A kind of electromagnetic flow transducer that is used to measure non-full pipe flow by a measuring tube, a pair ofly be installed in electrode on the measuring tube tube wall and one the magnetic field excitation unit that produces magnetic field in the measuring tube is formed, is characterized in that:

(a) described measuring tube axis is and is horizontally disposed with;

(b) described pair of electrodes is installed in the both sides of measuring tube inwall horizontal direction, and two electrodes are along the circumferential circular-arc a pair of long arc shape electrode that extends into of measuring tube tube wall, the arc length that the arc length of each electrode is covered corresponding to measuring tube non-full pipe liquid value H variation range;

(c) described magnetic field excitation unit is placed in the upper-lower position of measuring tube, produces the magnetic field of the vertical direction magnetic line of force, and promptly the face that forms of pair of electrodes is vertical in twos with rate of flow of fluid V with magnetic field B.

A kind of measuring method of non-full pipe flow adopts above-mentioned electromagnetic flow transducer, and its feature at measuring process is:

(a) produce under the situation of magnetic field B in the magnetic field excitation unit, on pair of electrodes, record induced potential value E;

(b) by the following relationship formula:

E＝K×D×B×V

Try to achieve the flow velocity V of fluid in measuring tube,

K is a design factor in the formula, is recorded by experiment; D is the internal diameter of measuring tube;

(c) do not produce under the situation in magnetic field in the magnetic field excitation unit, E=0 records the voltage U of generation with electric current I by electrode, by the following relationship formula:

U＝I×Z

Try to achieve the resistance value Z of measuring tube inner fluid;

(d) the level value H of the partly-filled pipe-flow that records according to experiment becomes dull corresponding relation with resistance value Z

H＝f(Z)

Try to achieve level value H;

(e) try to achieve the sectional area S of partly-filled pipe-flow in the measuring tube according to following formula

$S=\frac{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20061002923600061.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}\arccos \frac{D-2H}{D}-(\frac{D}{2}-H)\sqrt{\frac{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20061002923600061.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}-{(\frac{D}{2}-H)}^2}$

(f) last according to the flow velocity V and the sectional area S that have tried to achieve, try to achieve non-full pipe flow Q

Q＝V×S

The present invention compared with prior art, have following conspicuous outstanding substantive distinguishing features and remarkable advantage: as long as the electrode of traditional electrical magnetic flow transducers is transform as long arc type electrode, fluid impedance value Z and induced potential value E that electromagnetic flow transducer can be measured at different partly-filled pipe-flow states, and utilize impedance on the electrode and the dull corresponding relation of non-full pipe level value H, just can draw the flow value Q of non-full pipe flow by resistance value Z, induced potential value E and measuring tube diameter D.

Description of drawings

Fig. 1 is one embodiment of the present of invention structural principle block diagram, and (a) is for producing the situation of magnetic field B, (b) for not producing the situation in magnetic field among the figure.

Impedance-liquid level the curve of Fig. 2 long arc type electrode sensor

Embodiment

Details are as follows in conjunction with the accompanying drawings for a preferred embodiment of the present invention:

Referring to Fig. 1, the electromagnetic flow transducer that originally is used for measuring non-full pipe flow is made up of a measuring tube 1, a pair of electrode 2 and magnetic field excitation unit 3 that makes measuring tube 1 produce magnetic field that is installed on measuring tube 1 tube wall, it is characterized in that:

(a) described measuring tube 1 axis is and is horizontally disposed with;

(b) described pair of electrodes 2 is installed in the both sides of measuring tube 1 inwall horizontal direction, two electrodes 2 are along the circumferential circular-arc a pair of long arc shape electrode that extends into of measuring tube tube wall, the arc length that the arc length of each electrode 2 is covered corresponding to measuring tube 1 non-full pipe liquid value H variation range;

(c) described magnetic field excitation unit 3 is placed in the upper-lower position of measuring tube 1, produces the magnetic field of the vertical direction magnetic line of force, and promptly the face that forms of pair of electrodes 2 is vertical in twos with rate of flow of fluid V with magnetic field B.

The measuring method of this non-full pipe flow is to adopt above-mentioned electromagnetic flow transducer, and its feature at measuring process is:

(a) produce under the situation of magnetic field B in the magnetic field excitation unit, on pair of electrodes 2, record induced potential value E;

(b) by the following relationship formula:

E＝K×D×B×V

Try to achieve the flow velocity V of fluid in measuring tube 1,

K is a design factor in the formula, is recorded by experiment; D is the internal diameter of measuring tube 1;

(c) do not produce under the situation in magnetic field in the magnetic field excitation unit, E=0 records the voltage U of generation with electric current I by electrode 2, by the following relationship formula:

U＝I×Z

Try to achieve the resistance value Z of measuring tube 1 inner fluid;

(d) the level value H of the partly-filled pipe-flow that records according to experiment becomes dull corresponding relation with resistance value Z

H＝f(Z)

Try to achieve level value H;

(e) try to achieve the sectional area S of partly-filled pipe-flow in the measuring tube 1 according to following formula

$S=\frac{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20061002923600061.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}\arccos \frac{D-2H}{D}-(\frac{D}{2}-H)\sqrt{\frac{{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C20061002923600061.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}{4}-{(\frac{D}{2}-H)}^2}$

(f) last according to the flow velocity V and the sectional area S that have tried to achieve, try to achieve non-full pipe flow Q

Q＝V×S

Each electrode 2 arc length of Fig. 1 are that 0.1 * D determines with level value H minimum.Each electrode 2 arc length is the intersection points from the intersection point of H=0.1 * D to H=(1-0.1) * D=0.9 * D.

Fig. 2 is when measuring tube inside diameter D=50mm, and long arc type electrode sensor records the curve of the level value H of partly-filled pipe-flow in resistance value Z on the electrode and the measuring tube.

Claims (1)

1. the measuring method of a non-full pipe flow adopts the non-full pipe flow electromagnetic flow transducer to measure, and its feature at measuring process is:

(a) produce under the situation of magnetic field B in the magnetic field excitation unit, on pair of electrodes (2), record induced potential value E;

(b) by the following relationship formula:

E＝K×D×B×V

Try to achieve the flow velocity V of fluid in measuring tube (1),

K is a design factor in the formula, is recorded by experiment; D is the internal diameter of measuring tube (1);

(c) do not produce under the situation in magnetic field in the magnetic field excitation unit, E=0 records the voltage U of generation with electric current I by electrode (2), by the following relationship formula:

U＝I×Z

Try to achieve the resistance value Z of measuring tube (1) inner fluid;

(d) the level value H of the partly-filled pipe-flow that records according to experiment becomes dull corresponding relation with resistance value Z

H＝f(Z)

Try to achieve level value H;

(e) try to achieve the sectional area S of the interior partly-filled pipe-flow of measuring tube (1) according to following formula

$S=\frac{D^2}{4}\arccos \frac{D-2H}{D}-(\frac{D}{2}-H)\sqrt{\frac{D^2}{4}-{(\frac{D}{2}-H)}^2}$

(f) last according to the flow velocity V and the sectional area S that have tried to achieve, try to achieve non-full pipe flow Q

Q＝V×S

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