WO2015108292A1

WO2015108292A1 - Method for measuring density of liquid using magnetostriction

Info

Publication number: WO2015108292A1
Application number: PCT/KR2014/013053
Authority: WO
Inventors: 최인섭; 서무교
Original assignee: 산들정보통신 주식회사
Priority date: 2014-01-17
Filing date: 2014-12-30
Publication date: 2015-07-23
Also published as: CN104969053A; KR101415128B1

Abstract

The present invention relates to a technology wherein, when the density of a liquid is measured using the principle of magnetostriction, an induction formula between two floaters is used such that the unknown density can be measured accurately. To this end, according to the present invention, a correction point reference value is stored in advance on the basis of an effective sinking distance between a liquid surface floater and a density floater, and, when the density of a liquid to be measured is obtained later using the correction point reference value, a graph indicating the relationship between the effective sinking distance and the density is applied to a non-linear graph, which is similar to reality, thereby obtaining a density having a high degree of precision.

Description

Method for Measuring Density of Liquid Using Magnetostriction

The present invention relates to a technique for measuring the density value of a liquid using the principle of magnetostriction, and in particular, the density of the liquid using a magnetostriction to accurately measure the unknown density value by using an induction equation between two plotters It relates to a measuring method.

In general, a liquid density meter which measures the density value of a liquid by using the principle of magnetostriction is composed of a material having a lower density than the liquid to be measured and floated on the liquid surface to indicate the position of the liquid surface. It has a density plotter which is moved in the downward or upward direction depending on the density.

The liquid density measuring device measures the difference in the settlement distance between the liquid level plotter and the density plotter according to the density of the liquid in the state in which the liquid density measuring device is put in the liquid to be measured, and converts the difference in the measured settlement distance into the density value.

Hereinafter, the difference in the settlement distance between the liquid level plotter and the density plotter according to the density value of the liquid to be measured is referred to as "effective settling distance", and the settlement distance of each of the liquid level plotter and the density plotter according to the density value of the liquid to be measured is referred to as "submersion". Street ". Here, the settlement distance between the liquid plotter and the density plotter according to the density of the liquid to be measured means the difference between the settlement distance of the liquid plotter and the density plotter according to the density of the liquid to be measured.

At this time, the density plotter is stopped in a state where the buoyancy, which is the value multiplied by the volume of the liquid to be measured and the density value of the liquid, and the gravity due to the weight of the density plotter are in a floating position. The density plotter is moved downward if the density value of the liquid to be measured is low, and is moved upward if it is high. The floating principle of the density plotter is expressed by Equation 1 as follows.

Equation 1

At this time, some of the upper portion of the density plotter protrudes to the surface of the liquid to be measured. The smaller the cross-sectional area of the protruding portion, the density plotter is settled farther with respect to the same density value. This is because the volume change of the locked portion of the density plotter is constant with respect to the change in density value of the liquid to be measured, so that the smaller the cross-sectional area of the protruding portion of the density plotter, the larger the change in the effective settling distance. The effective settlement distance is not changed in a linear proportional relationship according to a change in the density value of the liquid to be measured, but in a nonlinear proportional relationship.

At this time, the settlement distance for the liquid density change of the liquid level plotter occurs relatively smaller than the density plotter.

In the conventional liquid density measuring technique, an effective settling distance according to the change of the density value of the liquid to be measured is measured in advance using a density meter, and a lookup table for the relationship between the measured effective settling distance and the density value. Build it.

Subsequently, when the unknown liquid density value is to be measured, the effective settling distance, which is added to the liquid and changes according to the density value of the liquid, is measured, and then the density value of the liquid to be measured is obtained using the lookup table.

However, when the density value of the liquid to be measured is obtained using the lookup table based on the effective settling distance, the graph does not obtain the density value by applying a graph that is nonlinearly changed as it is, and changes linearly for each section. Density values were obtained by applying to the graph considered to be. In other words, the density value of the measurement point for the corresponding settlement distance was determined by considering it as being linearly changed from the density value of the correction point in the immediately preceding and subsequent sections based on the measurement point.

As described above, in the conventional liquid density measurement technology, when the density value of the liquid to be measured is calculated using a lookup table based on the effective settlement distance between the liquid plotter and the density plotter according to the density value, the graph changes nonlinearly as in reality. Since the density value is obtained by applying to the graph that changes linearly by section, it is not possible to obtain the density value with high precision because of the actual nonlinear characteristics and the linear calculation error caused by the lookup table.

The problem to be solved by the present invention is to obtain a high accuracy by applying to a graph that is non-linearly changed from the two calibration point reference value when the density value of the liquid to be measured is obtained based on the effective settlement distance between the liquid plotter and the density plotter. It is to be able to find the density value which has.

Method for measuring the density of a liquid using a magnetostriction according to an embodiment of the present invention for achieving the above technical problem, (a) a liquid surface floater which floats to the surface of the liquid indicating the position of the surface, in the vertical direction in accordance with the density of the liquid A density measuring device including a density plotter, a magnetostrictive wire, and a density detecting unit installed in the density measuring unit; (b) a pulse supplied to the magnetostrictive wire whenever the liquid level plotter and the density plotter are introduced into liquids having different densities, a first magnetic body of the liquid level plotter, and a second magnetic body of the density plotter; A correction point reference value storing step of obtaining an effective settlement distance and a density corresponding to the effective settlement distance by using the magnetostriction generated by the liquid plotter and a density plotter, and storing a correction point reference value accordingly; (c) an effective settling distance measuring step of measuring an effective settling distance between the liquid level plotter and the density plotter by using the magnetostrictive phenomenon when the density detection unit measures the density of an unknown liquid; And (d) a density calculation step of calculating the density of the unknown liquid based on the correction point reference value stored in the step (b) and the effective settlement distance measured in the step (c). Include.

The present invention, when measuring the unknown liquid density value using the reference value of the two correction points based on the effective settlement distance between the liquid plotter and the density plotter, by applying a graph of the relationship between the effective settling distance and density to the actual nonlinear graph There is an effect that the density with high precision can be obtained.

1 is a signal flow diagram of a liquid density measurement method using a magnetostriction phenomenon according to an embodiment of the present invention.

2 is an overall configuration diagram of a density meter to which a density measurement method of a liquid using the magnetostriction phenomenon of the present invention is applied.

3A is a waveform diagram of a pulse output from the pulse generator to cause a magnetostriction phenomenon.

3B is a waveform diagram of an effective settlement distance detected by the calculation processing unit.

3C is a waveform diagram of a reference pulse string output from an oscillator to measure a time difference between two signal waveforms in a waveform diagram of an effective settlement distance.

4 is a relationship graph of settlement distance-density of a density plotter applied to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, Figure 1 is a signal flow diagram of a density measurement method of a liquid using a magnetostriction according to an embodiment of the present invention, as shown therein, comprising a density measuring device; A correction point reference value storing step of obtaining a reference value of density correction points; An effective settlement distance measuring step; And a density value calculating step.

FIG. 2 is an overall configuration diagram of a density meter to which a density measurement method of a liquid using the magnetostriction of the present invention is applied, and as shown therein, includes a density sensor unit 100 and a density detector 200.

The density sensor unit 100 is to be put in a container or a space containing the liquid to be measured density, the shape is not particularly limited, but in the present embodiment it is taken as an example that is configured in the form of a rod.

The density sensor unit 100 includes a metal tube 111 having a constant diameter and a vibration wave generator 120 mounted through a plurality of first spaces 112 installed in the metal tube 111.

The outer circumferential surface of the metal tube 111 is made of a material having a lower density than the liquid to be measured, which floats on the surface of the liquid to indicate the position of the liquid surface, and a density plotter 102 for measuring the density of the liquid to be measured. ) Is installed to be movable in the vertical direction, the first magnetic material 101A for causing a magnetostriction phenomenon is mounted in the liquid plotter 101, the magnetostrictive phenomenon is caused in the density plotter 102 The second magnetic body 102A is mounted.

The density plotter 102 is equipped with a weight (102B) having an appropriate weight therein to be locked to a position corresponding to the density of the liquid to be measured.

In addition, the density plotter 102 is equipped with a fluctuating wing 125. Therefore, when the density of the liquid to be measured is high, the density plotter 102 rises upward, and when the density is low, it sinks downward. The principle of immersion by the piercing wing 125 of the density plotter 102 is similar to that of the immersion density meter using a commercial weight.

The vibration wave generating unit 120 is inserted into and mounted in the metal tube 111, and the brass tube 121 and the insulating tube 122 and the section which are installed to overlap the inside of the brass tube 121. The magnetostriction wire 123 is installed to penetrate the center of the second space 124 at regular intervals in the interior of the association (122).

The density detector 200 includes a pulse generator 210, a pickup coil 220, a signal processor 230, an operation processor 240, a memory 240A, and an oscillator 250.

Referring to Figures 1 to 4 will be described with respect to the density measurement method of the liquid using the magnetostriction according to the present invention.

First, the density measuring unit 300 is a density plotter and a density detector including a liquid floater floating on the surface of the liquid indicating the position of the surface, the density plotter and a magnetostriction wire installed to flow in the vertical direction in accordance with the density of the liquid 200 is provided (S1).

At the required time before or after shipment of the density measuring device 300, the density measuring device 300 obtains an effective settlement distance and a density corresponding to the effective settlement distance, which are the difference between the settlement and the density plotter, and the effective settlement distance. The density, the correction point reference value corresponding to the effective settlement distance and the density are stored in the memory 240A (S2).

For example, as shown in FIG. 4, a liquid plotter and a density plotter injected into a liquid having a first density (d1 = 0.70 g / cm ³ ) measured by the high precision density meter (for example, a natural frequency measuring density meter). When the settlement distance of the liver is measured as the first effective settlement distance (le1) by the density meter 300, the correction according to the first effective settlement distance (le1) and the first density (d1 = 0.70 g / cm ³ ) Point reference values are stored in the memory 240A.

Similarly, the settling distance between the liquid level plotter and the density plotter injected into the liquid having the second density (d1 = 0.80 g / cm ³ ) measured by the high precision density meter is determined by the density meter 300 by the second effective settling distance ( When measured by le2), a correction point reference value according to the second effective settlement distance le2 and the second density d1 = 0.80 g / cm ³ is stored in the memory 240A.

Thereafter, the effective settlement distance between the liquid level plotter and the density plotter for the measurement target liquid contained in any container or space is measured using the density meter 300 as shown in FIG. 2 (S3).

In order to measure the density of the liquid to be measured, the pulse generator 210 generates a series of square wave pulses as shown in (a) of FIG. 3 and multiplies them to generate a sufficient magnetic field for magnetic deformation. .

The square wave pulse multiplied as described above passes through the pickup coil 220 and is supplied to the magnetostriction wire 123 of the density sensor unit 100. Accordingly, a magnetic field is generated in the magnetostrictive wire 123, and the magnetic field generated in this way moves in the longitudinal direction of the magnetostrictive wire 123 as the current pulse propagates.

When the magnetic field moved as described above encounters and interferes with the magnetic fields of the first magnetic body 101A of the liquid level plotter 101 and the second magnetic body 102A of the density plotter 102, the magnetostrictive wire 123 may have a mechanical minute. The modified oscillation wave (ultrasound wave) is generated by the variation of the length, and propagation occurs in both the reverse direction and the forward direction with respect to the traveling direction of the current pulse waveform. This phenomenon is called magnetostriction or magnetostriction. When the vibration wave transmitted as described above is transmitted to the pickup coil 220, the vibration of the ferromagnetic material in which the magnetic dipoles are arranged by the external magnetic field is disturbed, thereby changing the magnetic field in reverse, whereby both ends of the pickup coil 220. Induced electromotive force is generated.

The signal detector 230 detects the voltage induced in the pickup coil 220 through the above-described process, generates a detection signal accordingly, and then amplifies the signal to a level suitable for processing the signal at a later stage and is suitable for digital signal processing. The pulse is output in a stabilized form.

The oscillator 250 generates and outputs a reference pulse string having a predetermined pulse interval as shown in FIG. 3C using the crystal oscillator.

The arithmetic processing unit 240 measures the interval between the detection signal input through the signal detector 230, that is, the detection signal by the liquid level plotter 101 and the density plotter 102, from the oscillator 250. The measurement result is converted into the effective settlement distance between the liquid level plotter 101 and the density plotter 102. At this time, the conversion result can be corrected according to the ambient temperature.

In other words, the detection signal by the liquid level plotter 101 and the detection signal by the density plotter 102 indicate a time difference, and the arithmetic processing unit 240 performs the effective on the basis of this time difference. Calculate settlement distance.

In FIG. 3B, the effective settling distance lex between the liquid level plotter 101 and the detection pulses of the density plotter 102 input to the arithmetic processing unit 240 is shown. That is, the density plotter which is somewhat submerged from the surface of the liquid to be measured by the time when the detection signal by the liquid level plotter 101 located on the surface of the liquid to be measured is input to the calculation processing unit 240 and the density of the liquid to be measured. The time at which the detection signal by 102 is input to the calculation processing unit 240 has a difference. The calculation processor 240 calculates an effective settlement distance lex between the liquid level plotter 101 and the density plotter 102 based on the time difference. The effective settlement distance measurement process is the same as the process of measuring the first effective settlement distance and the second effective settlement distance in the second step (S2).

Thereafter, the calculation processing unit 240 calculates the density of the unknown liquid as shown in the following description based on the correction point reference value stored in the second step S2 and the effective settlement distance obtained in the third step S3. Compute (S4).

First, FIG. 4 is a graph showing that the settlement distance and the effective settlement distance of the liquid level plotter 101 and the density plotter 102 have a non-linear inverse relationship with density. Here, the measurement point MEA is a coordinate value on the settlement distance-density graph corresponding to the effective settlement distance lex of the density plotter 102 introduced into the measurement target liquid, and the first correction point COM1 is the second density d2. Is a coordinate value on a settlement distance-density graph corresponding to a first effective settlement distance le1, which is a settlement distance of the density plotter 102 injected into a liquid having a relatively low first density d1 compared to The correction point COM2 is a settlement distance-density graph corresponding to a second effective settlement distance le2, which is a settlement distance of the density plotter 102 injected into a liquid having a relatively high density compared to the second density d2. Coordinates of the phase.

In addition, the effective settlement distance lex means a settlement distance of the result of subtracting the settlement distance of the liquid plotter 101 from the settlement distance of the density plotter 102 based on the measurement point MEA. The first effective settling distance le1 means a settling distance of the result of subtracting the settling distance of the liquid level plotter 101 from the settling distance of the density plotter 102 based on the first correction point COM1. The second effective settling distance le2 refers to the settling distance of the result of subtracting the settling distance of the liquid level plotter 101 from the settling distance of the density plotter 102 based on the second correction point COM2.

In addition, in FIG. 4, the density dx means the density of the liquid to be measured corresponding to the effective settling distance lex. The first density d1 means a density corresponding to the first effective settlement distance le1. The second density d2 means a density corresponding to the second effective settlement distance le2.

Equation 2

Here, 'le1' is the first effective settlement distance, 'le2' is the second effective settlement distance, 'lex' is the effective settlement distance. 'd1' is the first density, 'd2' is the second density, and dx is the density.

That is, the density dx is proportional to a value obtained by multiplying the difference between the first and second effective settlement distances le1 and le2 by the first and second densities d1 and d2. In addition, the density dx is a value obtained by multiplying the difference between the first effective settlement distance le1 and the effective settlement distance lex by the first density d1, the effective settlement distance lex, and the second effective settlement distance le2. It is inversely proportional to the value obtained by multiplying the difference value of) by the second density d2.

In the example of Equation 2, the previous first effective settlement distance le1, the second effective settlement distance le2 and the first effective settlement distance adjacent to each other based on the effective settlement distance lex The first density d1 corresponding to le1) and the second density d2 corresponding to the second effective settlement distance le2 were substituted to obtain a density dx corresponding to the settlement distance lex. However, the present invention is not limited thereto. That is, even if two arbitrary settlement distances stored in the memory 240A and two densities corresponding to the two effective settlement distances are substituted into Equation 2, the same density is obtained. You can get it.

In other words, the density dx of the measurement object is between the first density d1 and the second density d2 (d1 <dx <d2), or the density dx is equal to the first density d1. Even when outside the second density d2 (d1 <d2 <dx) (dx <d1 <d2), the density of the liquid may be obtained using Equation 2 above.

The following table referred to as a first density d1 = 0.7 g / first effective subsidence distance le1 = 100 mm in cm ^3, and the second density d2 = 0.8 g / second effective subsidence distance in cm ³ le2 = 0 mm (the reference point) In this case, the effective settlement distances lex are the density dx values calculated using Equation 2 above.

Table 1

Effective distance between measured plotters (lex)	Converted density (dx)	Effective distance between plotters measured (lex)	Converted density (dx)
150	0.65882	70	0.72727
145	0.66272	65	0.73203
140	0.66667	60	0.73684
135	0.68066	55	0.74172
130	0.67470	50	0.74667
125	0.67879	45	0.75168
120	0.68293	40	0.75676
115	0.68712	35	0.76190
110	0.69136	30	0.76712
105	0.69565	25	0.77241
100	0.70000	20	0.77778
95	0.70440	15	0.78322
90	0.70886	10	0.78873
85	0.71338	5	0.79433
80	0.71795	0	0.80000
75	0.72258	-5	0.80576

As a result, as shown in FIG. 4, the first correction point COM1, the second correction point COM2, and the measurement points MEA are all located on a nonlinear graph representing a settlement distance-density relationship. Is defined by deriving the nonlinear graph as a simple equation. Therefore, the density dx obtained by Equation 2 ensures high precision.

In contrast, in the conventional density measurement technique, the measurement point MEA, the first correction point COM1, and the measurement point MEA and the second correction point COM2 are regarded as being present on a linearly changing graph. Since the density of the target liquid is obtained, an error occurs accordingly and high accuracy cannot be guaranteed.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and may be implemented in various embodiments based on the basic concept of the present invention defined in the following claims. Such embodiments are also within the scope of the present invention.

Claims

(a) a density plotter comprising a liquid level floater floating on the surface of the liquid to indicate a position of the surface, a density plotter installed to be able to flow in an up-down direction according to the density of the liquid, a magnetostrictive wire and a density detector in the density meter;

(b) a pulse supplied to the magnetostrictive wire whenever the liquid level plotter and the density plotter are introduced into liquids having different densities, a first magnetic body of the liquid level plotter, and a second magnetic body of the density plotter; A correction point reference value storing step of obtaining an effective settlement distance and a density corresponding to the effective settlement distance by using the magnetostriction generated by the liquid plotter and a density plotter, and storing a correction point reference value accordingly;

(c) an effective settling distance measuring step of measuring an effective settling distance between the liquid level plotter and the density plotter by using the magnetostrictive phenomenon when the density detection unit measures the density of an unknown liquid; And

(d) a density calculation step of calculating the density of the unknown liquid based on the correction point reference value stored in the step (b) and the effective settlement distance measured in the step (c). Density measurement method of a liquid using magnetostriction, characterized in that.
The method of claim 1, wherein the density in the step (b) is measured with higher precision than the required reference value.
The method of claim 1, wherein the correction point reference value is stored in a memory of the density detector.
The method of claim 1, wherein the magnetostrictive wire is installed on a path through which the liquid level plotter and the density plotter flow in the vertical direction.
The method of claim 1, wherein the density detection unit

A pickup coil connected to the magnetostrictive wire to generate induced electromotive force according to the magnetostriction phenomenon;

A signal detector for detecting a voltage induced in the pickup coil, generating a detection signal according to the pick-up coil, amplifying the signal, and outputting the amplified pulse in a stabilized pulse form; And

And a calculation processing unit for calculating the effective settlement distance based on the detection signal, and calculating a density of the unknown liquid based on the correction point reference value and the effective settlement distance. How to measure the density of.
The method of claim 1, wherein the liquid level plotter and the density plotter are respectively installed on an outer circumferential surface of the metal tube including the magnetostrictive wires.
The method of claim 1, wherein the step (d) calculates the density dx of the unknown liquid by using the following Equation.

Here, 'le1' is the first effective settlement distance obtained in the step of storing the correction point reference value,

'le2' is the second effective settlement distance obtained in the correction point reference value storing step,

'lex' is the effective settlement distance measured in the effective settlement distance measuring step,

'd1' is a first density corresponding to the first effective settlement distance,

'd2' is a second density corresponding to the second effective settlement distance.
The method of claim 7, wherein 'lex' is a settlement distance obtained by subtracting the settlement distance of the liquid plotter from the settlement distance of the density plotter based on a measurement point.
8. The magnetostriction of claim 7, wherein the 'le1' is a settlement distance as a result of subtracting the settlement distance of the liquid plotter from the settlement distance of the density plotter injected into a liquid having a lower density than the liquid to be measured. Method for measuring density of liquid used.
8. The magnetostriction of claim 7, wherein the 'le2' is a settling distance as a result of subtracting the settling distance of the liquid plotter from the settling distance of the density plotter injected into a liquid having a higher density than the liquid to be measured. Method for measuring density of liquid used.