FI63300C - MEASUREMENT OF THE PLACERING OF AV GRRAENSYTAN MELLANTVAO MATERIAL I EN BEHAOLLARE - Google Patents

Description

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C ..- Patent granted 10 05 1933 VgSJ • «« Patoni tonVnlat ^ ^ (SI) K <rjJ / lM.CL3 G 05 D 9 ^ 00 | FINLAND — FINLAND pi) ριημμ ^ -νιμιμ ^ ι 762015 • (22) HakemtapUvi — AMSknlnpdac O9.O7.76 '' (23) Alkupllvi —Glttlgh «ttdi | O9.O7.76 (41) Tullut JuIMmIuI - Blivic off «it) l |

Patent and Registration Office .... ...._____ . 12.01.77 _ ^ '(44) NlhtttvIluIpMon {· moonlight date. -

Patent- och registerstyreleen '' amMcu utU (d ocfc utLskrtfu «pubUcand 31 Q1 Q3 (32) (33) (31) Requested« importJk * u «—Ä.jtrd priorttat ^ Q ^ 23.07.75, 0i + .08.75, 01 * .08.75, 11.08.75, 11.08.75 USSR (su) 2156895, 2161009, 2162829, 2160657, 2161351, 2165621 * (Tl) Vsesojuzny Nauchno-Issledovatelsky i Konstruktorsky Institut "Tsvetmetavtomatika", Dmitrovskoe shosse, US, 129 (72) Nikolai Ivanovich Brazhnikov, Moscow, USSR (SU) (Jb) Oy Kolster Ab (5I +) Device for determining the location of the interface of two substances in a tank -Anordning för bestämning av placeringen av gränsytan mellan tvä material i en behällare

The present invention relates to the automatic control of technological parameters in different production processes in different industries by means of acoustic vibrations and in particular to a device for controlling the gas-liquid or liquid-liquid interface in single-layer tanks. The invention can be used in automated systems for controlling hydrometallurgical and ore enrichment processes in ferrous or non-ferrous metallurgy, chemical, petrochemical, food and other industries for automatic non-contact control of the interface of different substances in technological single-layer tanks.

Interface control is based on differences in some properties of such substances. The controlled production process may be characterized by various factors of instability of the properties of the substance, 63300, which interfere with the control of the gas-liquid and liquid-liquid interfaces. These factors include varying or decreased density of liquids, increased pressures and viscosity, changes in permittivity, agitation of the liquid with gas bubbles, a considerable layer of foam of varying consistency on the surface of the liquid, various suspensions within the liquid, and some other factors.

The main requirement for methods and apparatus for monitoring gas-liquid and liquid-liquid interfaces is to minimize the effect of said instability factors on the reliability and accuracy of the control. It is also required that the control method be sensitive, safe for the operating staff, that the device be simple in structure and that its market price be low.

Methods and devices can be used to monitor the interfaces, which according to their technological properties can be classified into two groups, a sensor group and a non-contact group. In the former methods and devices, sensing elements which provide information about the monitored interface are placed in a technological container containing said substances and in contact with these substances. As for the second group, the sensing elements are outside the controlled tank and not under the direct influence of the substances whose interface is monitored.

A floating method and apparatus for interface monitoring are known from the first group. This known method is based on placing a dense hollow body or a non-hygroscopic body with a low density (float) with a negative buoyancy relative to the upper substance and positive with respect to the lower substance, the interface of which is controlled. into the tank and the vertical displacement of said body is recorded, its position indicating a supervised interface. In addition to the float, the known device includes a system for registering the movement of the float. In such a system, an induction coil and an indicator showing the change in the electromagnetic field caused by the displacement of the float relative to the coil can be used.

However, this known method and apparatus has poor reliability and accuracy in monitoring the interface between viscous 3 63300 substances insofar as the float injects one of the substances and in monitoring the gas-liquid interface when a thick foam on the liquid surface surrounds the float some distance from the surface.

Similarly, a capacitive method and device for monitoring the interface are known, these also belong to the first group.

This known method is based on placing inside the container a sensing element having the shape of two plates (or rods) with a gap (gap) between them, and the capacity of said element is measured and this capacity depends on the permeability of the intermediate material and the interface is thus determined measured capacity. The known device includes, in addition to a capacitive sensing element, a measuring device for a change in the capacity of said element, which change occurs when the interface to be monitored moves relative to said recording device.

The known method and device for monitoring interfaces are disadvantageous in that their reliability is poor because the permeability of the substances varies and the distance between the sensing element and therefore its capacity changes due to the suspended particles in the substances.

Also known are an impedance method and device for monitoring interfaces, which method and device belong to the first group. This method is based on measuring the electrical impedance of an ultrasonic emitter inside a tank, which electrical impedance value changes as the interface passes the level at which the emitter is located. The device includes an ultrasonic emitter, an electrical vibration generator connected to it and a device for measuring the change in electrical impedance of the emitter.

Said known method and apparatus are characterized by a small dynamic range for monitoring the gas-liquid interface, relative to the density of the liquid substances, and insufficient reliability for monitoring the liquid-liquid interface. The latter drawback is due to the small difference between the electrical impedances of the emitter, the fluids whose interface is monitored acoustically attenuating t.

A disadvantage common to all the above methods and devices in the first group is also the need to place sensors inside the tank, which requires that the technological process be stopped when the device is installed, subjected to preventive monitoring and “63300 repairs”. In addition, the service life and reliability of these devices are greatly reduced when the tanks are filled with chemically highly reactive liquids.

Methods and equipment belonging to the second group do not suffer from these disadvantages.

A radioisotope method and device for monitoring interfaces are already known, these belong to the second group.

This method is based on determining the difference in the absorption of radioactive radiation passing through the technological tank in a direction which coincides with the axis of said tank, i.e. by measuring the absorption caused by the substances whose interface in the tank is monitored. The device with which said method is carried out comprises a source of radioactive radiation and a receiver located on different sides of the outer surface of the container, and a measuring device connected to the receiver.

The inherent disadvantages of this method and device for controlling interfaces are poor accuracy, complexity of structures, high market price of the device, and potential radiation hazards for operating personnel.

Similarly, a method and apparatus for monitoring gas-liquid and liquid-liquid interfaces in single-layer containers is known in the following.

This method is based on generating a wave of acoustic vibrations and sending it to the tank through a sound-conducting substance which touches a part of the wall of the single-layer tank; the acoustic wave is received after it has passed through the container and the second sound-conducting substance touching another part of the wall of the single-layer container, and the gas-liquid or liquid-liquid interface is determined from the amplitude of the transmitted acoustic wave. Changes in amplitude are caused by a difference in the passage of an acoustic wave inside the tank through substances whose interface is controlled by this method.

A device for monitoring a gas-liquid or liquid-liquid interface in single-layer tanks is already known, which comprises an Allon emitter of acoustic vibrations connected to an electric vibration generator, an acoustic wave receiver located in the path of said wave emitting from said emitter, the receiver and the emitter being located in wherein the contact areas of said audio conductors contact the wall of the container and their effective areas are in contact with respective areas in the sound wave emitter and the receiving groove, the output of said receiver being connected to a circuit formed by an amplifier of electrical signals coming from the receiver and amplifying said electrical signals the measuring device (recording device) is connected in series and the amplitude is used to determine the seasonal-liquid or liquid-liquid interface.

The above-mentioned method for controlling gas-liquid and in particular liquid-liquid interfaces and the device for carrying out this method when used in numerous industrial processes, e.g. ore beneficiation, hydrometallurgical or chemical processes, do not provide the required control accuracy, leading to significant errors, complicating the device structure and increase its market price.

These disadvantages are due to the fact that when the cross-sections of the tanks are up to 8-10 meters, this causes a sharp refractive divergence in the acoustic wave, whereby the amplitude of the acoustic wave is considerably reduced in the receiving area. To reduce the effect of refraction, the size of the emitter and the frequency of the transmitted wave should be increased, which in turn requires a significant improvement in the power of the electric vibration generator, and this brings with it a corresponding increase in device complexity and cost.

In addition, the presence of gas bubbles and solid particles in the liquid substance inside the container causes a considerable scattering of the acoustic wave propagating in these substances, whereby the amplitude of the received wave decreases exponentially as the size of the container increases. All of this results in considerable errors and in many cases the said method and apparatus become unusable or impractical.

It is an object of the present invention to provide an apparatus for monitoring gas-liquid and liquid-liquid interfaces in single-layer tanks, which ensures control over a wide range of physicochemical compositions, conditions and properties of substances.

Another object of the present invention is to increase the accuracy of interface monitoring.

6 63300

Another object of the invention is to simplify the structure of the device and reduce its operating costs and market price.

The above objects are achieved by a device for determining the location of the interface of two substances with different acoustic properties in a tank by a sound source connected to one point of the tank wall for conducting an acoustic wave to the tank wall; a sound receiver connected to another point in the tank wall and means for determining the amplitude of the acoustic wave received by the sound receiver as an indicator of the location of the interface.

The device according to the invention is characterized by a combination of the following features: a) the sound source is connected to the tank wall via a first sound conductor leading an acoustic wave from the sound source at an acute angle to the tank wall, where mechanical vibrations propagate in the direction and direction determined by the acoustic wave propagation direction and angle approximately equal to the speed of propagation of the acoustic wave in the wall of the tank under the simultaneous action of the substance in contact with the inside wall of the tank, b) the sound receiver receives via the second sound line an acoustic wave whose amplitude determines the height of the interface.

Furthermore, the device according to the invention is characterized in that a) in each sound conductor the contact surface with the wall of the container and its respective surface with the sound source are at an angle Θ with respect to each other, which is determined by the formula

C

Θ = arc sin _3 C

(b) and the sound conductors are made of a material in which the rate of propagation of acoustic waves is less than the rate of propagation of mechanical vibrations in the tank wall.

In case the cross-section of the tank wall is variable, it is recommended to make the audio conductors from two parts with different materials as well as acoustic wave propagation speed in them, the parts having cylindrical contact areas and the axis of symmetry of these areas the radius of the contact areas is not determined until:

Ci + ^ 2 ~ R - C2-ri c- - c ~ A cot θ '4 1 2 where and C2 are the maximum and minimum propagation velocities of the mechanical vibrations in the wall part of the container which are vibrated by the wave of acoustic vibrations; C4 3a C5 are the wave propagation velocities of the acoustic vibrations in different parts of the sound conductors; A is the length of the effective part of the sound conductors in a plane passing through the line coinciding with the direction of propagation of the mechanical vibrations excited on the wall of the container and through the normal of this region; this feature ensures the divergence or convergence of the acoustic vibration wave.

In the case where the cross-section of the tank wall is variable, it is expedient for the effective area of the sound conductors to be cylindrical and the radius of curvature to be determined from the equation: 8 to 1707¾ · Ä ctg 8.> The sound source and sound receiver are made so that their effective area is effective ranges, a feature that ensures wave divergence or convergence of acoustic vibrations.

In the event that the cross-section of the tank wall is variable, it is also expedient that the length A of the effective areas of the sound conductors in a plane passing through the normal and straight line of said area coinciding with the direction of mechanical vibrations of the tank wall is given by the formula: H ^ K '_ - / ^ cot θ, where k is a factor determined by the effective ranges of the audio conductors; is the wavelength of the acoustic oscillations in the audio conductors, the minimum distance H. between the effective contact areas is determined as follows: 63300 a2 “min TTT cos S 'this feature ensures the divergence or convergence of the acoustic vibration wave

It is also expedient to make audio conductors in the device from fused quartz or porcelain or silicate glass or lead or tin or lead-tin alloys with an acoustic impedance in the range of 0.3 to 1.7 times the acoustic impedance of the sound source for the transmitted acoustic wave and the acoustic input.

It is also possible to make sound conductors based on aqueous solutions of alcohols or alkalis or acids or salts of inorganic acids with an approximately parabolic temperature dependence of the acoustic wave propagation speed, the concentration of the solutions being chosen so that the maximum acoustic wave propagation velocity is

The device described above for monitoring the gas-liquid or liquid-liquid interface in single-layer tanks has a number of advantages over known devices.

The device described above allows for a significant reduction in errors when monitoring interfaces in single-layer tanks and thus an improvement in the accuracy and reliability of monitoring.

First, the device proposed here completely eliminates control errors due to the refractive divergence of the acoustic wave in substances whose interface is controlled in the tank, because it is not necessary to measure the propagation of the wave in said substances. The refractive effect of the mechanical vibrations propagating in the wall measured according to the present invention is quite weak and in practice does not affect the accuracy of the control.

Second, the device proposed here completely eliminates the errors caused by the considerable scattering of the propagating acoustic wave in those liquid media whose interface must be monitored. This is achieved by the fact that the parameter used in the present device to determine the interface 9 63300 is the amplitude of the acoustic wave converted from mechanical vibrations propagating along the tank wall, the propagation of these vibrations being independent of acoustic wave scattering in liquid media filling the controlled tank.

In addition, the device for carrying out the method proposed here is substantially simplified according to the invention and makes it possible to use a smaller sound source and a substantially lower power electric vibration generator. This becomes possible due to the fact that in this proposed device there is no need to greatly increase the power of the acoustic wave, whereas in the previously known devices this is necessary to ensure the passage of the acoustic wave through large industrial tanks. In the device shown here, such a strong increase in acoustic wave power is avoided due to the fact that the informative acoustic wave is received by the receiver in a part remote from the part where the acoustic wave is transmitted practically by one order of magnitude and also due to the smaller cross-section of the container.

Other objects and advantages of the device for monitoring the gas-liquid and liquid-liquid interface proposed herein will become more fully apparent from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings.

Figure 1 is an overview of a single-layer tank with a sound source or acoustic wave emitter and receiver according to the invention mounted on its side wall.

Figure 2 shows a top view of the same arrangement according to the invention as Figure 1 (the container is illustrated in cross section).

Figure 3 shows an apparatus according to the invention for monitoring a gas-liquid or liquid-liquid interface in single-layer tanks provided with sound conductors according to a first embodiment of the invention (the tank is described in longitudinal section).

ίο 63300

Fig. 4 shows a part of the wall of the container on which the wave emitter of acoustic vibrations is mounted by means of sound conductors made according to a second embodiment of the invention (partial longitudinal section).

Figure 5 is a side view of the same arrangement as shown in Figure 4.

Fig. 6 shows a part of a wall of a container on which an acoustic vibration wave emitter is mounted by means of sound conductors made according to a third embodiment of the invention (partial longitudinal section).

Figure 7 is a side view of the same part as illustrated in Figure 6.

Fig. 8 shows a part of the wall of the container on which the wave emitter of acoustic vibrations is mounted by means of sound conductors made according to a fourth embodiment of the invention (partial longitudinal section).

Figure 9 is a side view of the same part as illustrated in Figure 8.

Fig. 10 shows the same device as illustrated in Fig. 3, provided according to the invention with an electronic channel for the passage of a reference internal signal in the electrical circuit of the proposed device.

Fig. 11 shows the same device as illustrated in Fig. 3, when the audio conductors are made according to a fifth embodiment of the invention and the device according to the invention is provided with an electronic channel for passing a reference signal in the electrical circuit of the proposed device.

Fig. 12 shows the same device as illustrated in Fig. 3 when the audio conductors are made according to a sixth embodiment of the invention and the device according to the invention is provided with an electronic channel for the transmission of a reference signal in the electrical circuit of the proposed device.

Fig. 13 shows the same device as illustrated in Fig. 3 when it is provided with an electric circuit which, according to the invention, produces a pulse generation of a wave of acoustic vibrations.

Fig. 14 shows a part of a wall of a container on which a wave emitter of acoustic vibrations is mounted by means of an audio conductor 63300 made according to a seventh embodiment of the invention (partial longitudinal section).

Fig. 15 shows a part of the wall of the tank on which the wave emitter of acoustic vibrations is mounted! by means of an audio conductor made according to an eighth embodiment of the invention (partial longitudinal section).

Fig. 16 shows a part of a wall of a container on which a wave emitter of acoustic vibrations is mounted by means of an audio conductor made according to a ninth embodiment of the invention (partial longitudinal section).

Fig. 17 shows a part of a wall of a container on which a wave emitter of acoustic vibrations is mounted by means of an audio conductor made according to a tenth embodiment of the invention (partial longitudinal section).

Fig. 18 shows a part of a wall of a container on which a wave emitter of acoustic vibrations is mounted by means of an audio conductor made according to an eleventh embodiment of the invention (partial longitudinal section).

Fig. 19 shows a part of a wall of a container on which a wave emitter of acoustic vibrations is mounted by means of an audio conductor made according to a twelfth embodiment of the invention (partial longitudinal section).

Fig. 20 shows a part of a wall of a container on which a wave emitter of acoustic vibrations is mounted by means of an audio conductor made according to a thirteenth embodiment of the invention (partial longitudinal section).

The proposed device for monitoring the gas-liquid and liquid-liquid interfaces in a single-layer tank comprises an emitter 1 (Fig. 1) of acoustic vibration wave 2 (Fig. 2) mounted by an audio conductor 3 containing gaseous and liquid material 6 (Fig. 1) and 7 and their interface 8. on the wall 4 of the single-layer tank 5. The emitter 1 is mounted on the part 9 in such a way that mechanical vibrations 10 are excited by the transmitted acoustic vibration wave 2 in the wall 9 part 9 (Fig. 2), which mechanical vibrations propagate in a predetermined direction.

The device also includes a receiver 12 for an acoustic wave 13 converted from mechanical vibrations 10, which is mounted on the part-13 9 by means of an audio conductor 11 which is in the path of propagation of the mechanical vibrations 10. An electric oscillation generator 14 (Fig. 3) is connected to the emitter 1 and a circuit formed by a series-connected electrical signal amplitude measuring device 17 (Fig. 1) is connected to the receiver 12, the amplitude of said electrical signals depending on the type of substance 16 contacting the wall part 4, this substance is above or below interface 8 (Figure 1).

In order for the speed of the acoustic vibrations Allon 2 transmitted to the tank 5 along the wall 4 to be approximately equal to the speed of the mechanical vibrations 10 along said wall, the effective area 18 of the sound conductors 3, 11 on which the emitter 1 and the receiver 12 are mounted and these sound conductors 3 , 11 the contact area 19 is at an angle Θ to each other, said angles Θ are determined by the following formula: Θ = arc <^ in (1) where Cg is the propagation speed of the acoustic waves 2, 13 in the sound conductors 3, 11; C is the rate of propagation of the mechanical vibration 10 generated by the acoustic wave 2 along the wall 4 of the container 5.

The sound conductors 3, 11 are made of a material in which the propagation speed of the acoustic wave 2, 13 is lower than the propagation speed of the mechanical vibration 10 in the wall 4 of the container 5.

The audio conductors 3, 11 can be made of either the same material or different materials. In the latter case, which follows from formula (1), the angles Θ of the audio conductors 3, 11 are also different. In all the following exemplary embodiments, the audio conductors 3, 11 are assumed to be made of the same material. In the embodiment described here, the audio conductors 3, 11 are made of plexiglass and may also be made of a 16% solution of ethyl alcohol.

The sound conductors 3, 11 are mounted so that their contact surfaces 19 are on the wall 4 of the container 5 with a part 9 raised by a flange 20 fixed by pins (not shown in the drawing) preliminarily welded to the container S and passing through appropriate holes in the flange 20. It is also possible to use another version in which the flange 20 is glued to the wall 4 of the container 5.

In the embodiment to be described here, a part of the surface of the sound conductors 3, 11 is coated with a layer 21 of an acoustic wave absorbing substance, which is a mixture of an epoxy resin and a polymerizing agent, as a tungsten powder filler.

i3 6330 0

The piezoelectric type emitter 1 is used as the wave emitter 1 of the acoustic oscillations (see e.g. U.S. Patent No. 2,932,223). The receiver 12 has the same structure as the emitter 1. The generator 14 uses a known continuous crystal-stabilized oscillator circuit. The amplitude measuring device 17 for electrical signals is manufactured according to a known diagram of an analog measuring device (see, e.g., U.S. Patent 3,345,861). The measuring device 17 can be made as a relay block when relay contact signaling is required to indicate that the interface to be monitored is at a predetermined level.

The device described above is the simplest for the case where the cross-section of the wall 4 of the container 5 is constant.

The effect of the varying cross-section of the wall 5 of the tank 5 on the control of the interface 8 between substances 6 and 7 (Figure 1) can be reduced by excitation of the wall 5 of the tank 5 with a divergent or convergent wave of acoustic oscillations and selecting the input angle from the formula: ι C2 where and are the input angles of the acoustic vibrations Allon 2 (Fig. 3) determined from the direction of propagation of said wave 2 and the normal input zone of the wall 4 of the container 5;

Ci and C2 are the maximum and minimum propagation velocities of the mechanical vibration 10, respectively, in the part 9 of the wall 4 of the container 5, which mechanical vibration is excited by the acoustic vibration wave 2.

For each value of the varying cross section of the wall 4 in the range di - d2, there is an incident angle which satisfies the condition that the velocity of the introduced wave 2 is the same as the mechanical vibration 10 propagation speed in the thickness range of the wall 4 in question.

In order to produce a convergent or divergent wave in the angular range & i - §2, each of the sound conductors 3, 11 according to the first embodiment (Fig. 4) is made of two parts 22 and 23 whose materials differ in the speed at which the acoustic vibration waves 2, 13 ( Figure 3) proceed in them. The parts 22 (Fig. 4) and 23 have a cylindrical contact area 24, the axis of symmetry of which is in the same plane as the axis 14 of the emitter 1 and the receiver 12 (Fig. 3) perpendicular to said axes 63300. The radius of the contact areas 2¼ (Fig. H) is determined by the following formula: L, + C- - Cg R <—-— —I-— A cot Θ, (3) C4 + C5 C1 "C2 where and Cg are the propagation velocities of the acoustic wave 2, 13 · A is the length of the effective area 18 of the sound conductors 3, 11 in a plane passing through a line coinciding with the direction of propagation of the mechanical vibration 10 excited in the wall 4, and through 18 normal in this range.

The central beam 25 of the acoustic wave 2 (Fig. * 4) passes through the contact area 24 without bending and enters the wall 4 at an angle of inclination which forms an angle Θ with the normal area 18 of the sound guide part 3. The side rays 26 and 27 fold in said region 24 and enter the wall 4 at angles and θ2 which are respectively larger or smaller than the incident angle Θ of the central beam 25. In order to avoid volume reverberation of the sound conductors 3, 11 (Fig. 3) caused by multiple reflections of the acoustic waves 2, 13, said sound conductors 3, 11 are partially coated with a layer 21 (as in the embodiment shown in Fig. 3) of a substance which absorbs sound waves.

The reduction of the effect caused by the variation in the thickness of the wall 4 of the container 5 is also achieved by making the effective area 18 of the emitter 1 audio conductor 3 (Fig. 6) and receiver 12 audio conductor 11 (Fig. 3) cylindrical with radius of curvature R (Fig. 6). and between the length A of this region 18 in a plane passing through the normal and straight line of said region 18 coinciding with the direction of propagation of the mechanical vibration excited by the wall 4 is determined by the formula: A about ~ ^ 9 -> 2 -2— tan Θ (4) R ci + c2

The emitter 1 and the receiver 12 (Fig. 3) are made in the shape of a hollow cylinder part having an internal radius of curvature equal to the radius R of the effective area 18 of the audio conductors 3, 11 (Fig. 3); the convergent beam is introduced into the wall 4 in the range of angles 0 ^ - 02 (Fig. 6), which ensures the optimal excitation of the mechanical vibration 10 in the part of the wall 4 when the wall thickness varies from d - ^ to d2. The effect of variations in the thickness of the wall 4 of the container 5 is also reduced by the fact that the length A of the effective area 18 of the sound conductors 3, 11 (Fig. 3) in the plane passing through the normal and straight line of this area 18 coincides with the direction of mechanical vibration. provides for the formula:

C + C

K -Λ- λ .cot 0, (5) where k is a coefficient determined by the shape of the effective area 18 of the audio conductors 3, 11 and equal to 0.86 for the circular effective area and 0.7 for the rectangular area; (numerical values are obtained from analytical expressions for directional patterns of emitters whose emitting surfaces have the above-mentioned shape); ^ is the wavelength of the acoustic vibrations 2, 13 in the sound conductors 3, 11; 0 is the angle of inclination of the effective area of the audio conductors 3, 11.

The minimum distance H 1 (Fig. 9) between the effective area 18 and the contact area 19 "of the sound conductors 3, 11 is determined by the formula: A2 v -. Cos Θ (6)

Hmin s 4 A.

As a result, the planar front 28 (Fig. 8) in the acoustic wave 2, after maintaining distance B, approaches the contact areas 19 into a partially spherical front with diverging rays having an angle of incidence in the wall 4 in the range from a maximum angle of 0 to a minimum angle 02. Said angles ensure optimal vibration in the wall 4 of the container 5 in its thickness range d- ^ dj · The instability of the acceleration of the acoustic oscillation wave 2 (Fig. 10) of the sound conductor 2 used to excite the mechanical vibration 10 in a certain part of the wall 4 of the container 5 is eliminated by including an additional circuit 29 is adapted to generate an electrical reference signal from the electrical oscillation of the generator 14, the input of the former of which is connected to the output of the generator 16, 63300, a block 30 for comparing the informative electrical signal with the reference signal, and a former 31 adapted to generate the informative an electrical signal from the electrical signals of the amplifier 15, the input of the former of which is connected to the output of the amplifier. The output of the reference block 30 is connected to a measuring device 17, which is supplied with a signal which, depending on the purpose of the monitoring, is proportional to either the difference or the ratio between the informative and the reference electrical signal.

In the illustrated embodiment of the device, the effect of the electric vibration amplitude instability of the generator 14 on the accuracy of the gas-liquid or liquid-liquid interface 8 gain between the monolayer 5 materials 6 and 7 (Fig. 1) is eliminated due to the same effect on the electronic reference signal and the informative signal. amplitudes.

The conditions under which the acoustic wave 2 (Fig. 10) is passed through the contact area 19 to the wall 4 may vary during operation, which means changes in the amplitude of the mechanical vibration 10 in the area 9 of the container 5 wall 9 and consequently errors in interface 8 monitoring (Fig. 1).

To eliminate these errors, the mechanical vibration in the part 9 of the wall 4 of the container 5 is excited by a second custic wave whose damping of the latter mechanical vibrations is different from the damping of the mechanical vibrations excited by the primary wave. Interface 8 is determined by the relationship between the amplitudes of the mechanical vibrations excited by the primary and secondary waves.

In order to realize the secondary excitation of the mechanical vibration in the wall 4 of the container 5 by an acoustic vibration wave, two embodiments of the device have been proposed, which are illustrated in Figures 11 and 12.

According to the former, the device includes the above-mentioned emitter of acoustic vibration wave 2 connected to an electric vibration generator 14 and mounted on an audio conductor 3 and an acoustic wave 13 receiver 12 connected to an amplifier 15 and mounted on an audio conductor 11. The embodiment of the device now described also includes a measuring device ( recording apparatus) 17, a reference electrical signal shaper 29, a block 30 for comparing an informative electrical signal with a reference signal, and a shaper 31 for comparing an informative electrical signal.

17 63300

In the embodiment of the device now described, the sound conductors 3 and 11 have an effective additional area 32 which forms an angle f with the contact area 19, which angle is selected from the formula:

Q

Ί ”= arc ^ in -, (7) C6 where Cg is the rate of propagation of the mechanical vibration which is secondary excited in the part 9 of the wall 4 of the container 5.

The device also has an additional emitter 33 for the acoustic vibration wave 34 and an additional receiver 35 for the acoustic wave 36, which emitter and receiver are mounted in the effective additional areas 32 of the respective audio conductors. connected to the auxiliary receiver 35 of the acoustic wave 36, which wave 36 is converted from the mechanical vibrations 38 which were secondary excited in the wall 4 by the wave 34, the damping of these mechanical vibrations 38 is different from the damping of the primary excited mechanical vibrations 10. The output of the amplifier 37 is connected to an input in a shaper 29 adapted to shape the reference electrical signal and to be connected to the input of the block 30 for comparison of the informative electrical signal with the reference signal. The second input of the reference block 30 is connected to the output of a molding 31 adapted to generate an informative electrical signal, the input of this molding being connected to the output of the amplifier 15. The output of the reference block 30 is connected to the measuring device 17.

In the present embodiment of the device, it is expedient to select the distance E between the projections of the effective main area 18 and the additional area 32 centers in the contact area 19 from the formula E = tan Θ - tan (8) where and H ^ are the distances between the effective main and additional areas 18 and 32 of the audio conductors 3 and 11. and the contact area 19.

18 63300

The use of an additional acoustic channel (emitter of the acoustic oscillation wave 34 - mechanical oscillation 38 in the wall 4 - receiver 35 of the wave 36) and a reference signal electric circuit (amplifier 37-shaper 29) makes it possible to formally increase the control accuracy in case of instability during oscillation a wave in the wall 4 through the contact area 19 of the sound conductor 3 and when receiving the wave 13 in the sound conductor 11 via this contact area 19.

In the embodiment shown in Fig. 12, the sound conductors 3 and 11 have a reflection area 39 for ensuring secondary excitation of part 9 of the wall 4 of the container 5 by acoustic vibration wave from the einiter 1, said reflector forming an angle with the effective area 18, this angle is determined by the formula:

Q

A = - - (Θ - arc Iin -) (9)

'2 * C

The secondary excitation of the mechanical vibrations 38 in the wall 4, where it propagates at a speed Cg, is effected by an acoustic vibration wave 34 converted from the wave 40 of the emitter 1 after the wave 40 is reflected from the reflection region 39. An additional wave 36 converted from the secondary excited mechanical vibration from the reflection region 39 in the audio conductor 11 and after conversion to the acoustic wave 41, is received by the same receiver 12 which receives the acoustic wave 13. The electric circuit of the present embodiment of the device is formed by block 30 for comparing the informative electrical signal with the reference signal. The circuit also includes a reference electrical signal generator 29, the input of which is connected to the input of block 30 and a second block 43 for selecting electrical signals, the input of which block is also connected to the output of amplifier 15 and the output of block 43 is connected to the input of generator 29. The electrical circuit includes a selection pulse generator 44, the outputs of which are connected to the controlled inputs of the selection blocks 42 and 43.

19 63300

In the present embodiment, a generator of pulse amplitude modulated oscillations (each modulation period has durations) is used as the electric oscillation generator 14, and the input of the selection pulse generator 44 is connected to the output of said generator. The selection blocks 42 and 43 are formed, like a previously known circuit, from an amplifier having a controlled additional weather input for a selection pulse which coincides in time with the reception of the selection signal from the electrical signal amplifier 15. The selection pulse generator 44 is a gate pulse

I.N. Yermolov, "Methods of Ultrasonic Flew Detection," in Russian, Moscow, MGI Publishers, 1966, pp. 118-119).

When controlling the interface 8 (Fig. 1) between substances with significantly different physical properties, the frequency of mechanical vibrations 10 (Fig. 2) in the excited part 9 of the wall 4 of the container 5 changes with said interface location, whereby the conditions under which said mechanical vibration 2 is excited by acoustic vibration , changing; the amplitude of these mechanical oscillations and the amplitude of the electrical oscillations at the output of the receiver 12 decrease. All of this can cause significant errors when monitoring interface 8 (Figure 1).

To eliminate these adverse effects, a portion 9 of the wall 4 (Fig. 2) of the container 5 is periodically excited by a pulsed wave 2 of acoustic vibrations selected from a range exceeding the frequency range of the mechanical vibrations 10 in the wall 5 of the container 5 at different points 8 (Fig. 1). with respect to the oscillating part 9. This ensures that the mechanical vibration 10 (Fig. 2) is excited in the wall 4 by the wave 2 at the frequency of these vibrations regardless of the location of the interface 8 (Fig. 1) and thus the type of substance 16 (Fig. 3) contacting the inner surface of the excited part 9 . The filling frequency of the acoustic pulse wave 13 is also determined and said frequency is used to determine the type of liquid when the interface 8 (Fig. 1) is located above or below the vibrating part 9 of the wall 4 (Fig. 2) of the container 5.

In order to carry out periodic excitations of the wall 4 part 9 with an acoustic oscillation pulse wave in the present embodiment, the 63300 electric vibration generator 14 (Fig. 13) in the electric circuit includes a broad-spectrum electric pulse generator , the input of which is connected to an electric signal amplifier 15, a block 30 for comparing an informative signal with a reference signal, the input of the block 30 of which is connected to the output of a shaper 31; The electrical circuit also includes a block 47 adapted to measure the frequency of the electrical signal and having an input connected to the output of the electrical signal amplifier 15. The output of the reference block 30 is connected to the measuring device 17.

In the present embodiment of the device, the broad-spectrum electric pulse generator 45 is made like an electric video pulse generator using a known barrier oscillator circuit. The duration of these video pulses ^ is selected from the formula:

To = ° '5 fo ~ (10) where Fq is the average passband frequency of the emitter 1 and consequently of the receiver 12.

If a piezoelectric plate is used as an active element in the emitter and receiver, the value of f is the frequency of the resonant oscillations of this plate.

In the present embodiment of the device, the power amplifier 46 is made according to a known emitter follower circuit.

The frequency of the primary excited mechanical vibrations 10 and the secondary excited mechanical vibrations 38 (Figures 11, 12) changes with variations in the cross section of the excited wall portion of the container. This changes the excitation conditions of these oscillations and their subsequent conversion into an acoustic wave and consequently reduces the amplitude of said mechanical oscillations and the magnitude of electrical signals at the outputs of the receivers 12, 35 of the acoustic waves 13, 36 converted from mechanical oscillations 10, 38; as a result, considerable errors occur in the control of the interface 8 (Fig. 1).

To reduce these errors, a portion 9 of the wall 4 of the tank 5 21 (Fig. 2) is periodically excited by a pulsed wave of acoustic vibration whose relative spectral width is selected to be equal to or greater than the relative change in the thickness of the vibrating portion 9 of the wall 5 of the tank 5: AF 2 (f, - f,) 2 (d, - d9) f - -2 --- i-2— UI) 3 + f2 <4 ♦ d2 where f = is the absolute value of the width of the pulse wave spectrum of the acoustic oscillation; f2 and are the respective upper and lower limits of the acoustic pulse wave spectrum; f3 = 0.5 (^ + £ 2) is the average frequency of said spectrum; d · ^ and d2 are the respective maximum and minimum thicknesses of the wall 4 of the container 5.

To implement the present technical solution, the sound conductors 3, 11 in Fig. 13 are made of fused quartz or porcelain or silicon or tin or lead or tin-lead alloys with an acoustic impedance Z in the range of 0.3 to 1.7 times that of the acoustic wave emitter 1 and the acoustic impedance of the receiver 12.

The average values for the acoustic impedance Z (dimension 6 2 ^ is 10 kg / m s) for X-shaped quartz crystals, lead methaniobate, barium titanate and lead zirconate titanate of piezoelectric emitters and receivers are given in Table 1.

Table 1 X-shaped lead metabium titanate lead zirconate quartz crystal niobate_titanate_ 15.2 16 30.2 36.5

The average values for the acoustic impedance Z (dimension 6 2 10 kg / m s) and velocity (m / s) in the audio conductors 3, 11 made of said materials are given in Table 2.

22 63300

Table 2

Material Fused Porcelain Silicon Glass Tin Lead Tin-Lead alloys,% _quartz__ '__ Z 13 13.5 15 24.2 24.6 25 + 75 50 + 50 75 + 25 24.3 24.4 24.5 C3 5,570 5,600 5,500 3,320 2,160 3,030 2,740 2,450 This makes it possible to considerably widen the spectrum of the acoustic vibration wave in order to reduce the errors caused by the variable cross section of the wall 4 of the container 5.

The temperature of the sound conductors 3, 11 and consequently the speed of the acoustic vibration wave 2, 13 changes with the temperature of the wall 4 of the tank 5. As a result, the conditions (1) and (7) for the primary and secondary excitation of the mechanical vibration 10, 38 (Figs. 11, 12) in the wall 4 of the container 5 become disturbed and additional temperature-induced errors occur in the control of the interface 8 (Fig. 1).

These errors are reduced by the special design of the audio conductors 3, 11, which in the following embodiments of the device in connection with Figures 14-20 will be explained using the audio conductor 3 as an example.

The shape of the audio conductors 3 shown in Figs. 14 to 20 is similar to that shown in Figs. 3, 4, 6, 11 and 12.

However, the sound conductors 3 in the embodiments shown in Figs. in the region of the average temperature t of the wall 4 of the tank 5.

The following is Table 3, which shows the values and t for water and a number of aqueous solutions of various substances: sulfuric acid I having said parabolic temperature dependence of the propagation speed of the acoustic vibration wave 2.

23 63300

Table 3

H 2 O 2 SO 2 HNO 3 HCl NaOH dissolved in water

Substance_q,% 0 33 20 27 2 «+ 30 8 12 t, ° C 70 30 50 30 50 30 50 30 C3max 111/3 1,555 1,565 1,520 1,525 1,530 1,510 1,760 1,860

Dissolved in water

Substance C ^ OH ZnSO 4 HCONI ^ CHgCN

q,% 12.5 16 6.7 12 20 36.5 10 17 t, ° C 40 20 60 40 50 30 50 30 C, m / s 1.580 1.605 i »630 1.665 1.565 1.575 1.550 1.545 Audio conductors 3 shown Figures 14, 18 and 20 consist of a hollow body 48 filled with an aqueous solution of a material selected from Table 3 and having said parabolic temperature dependence of the Allon propagation speed of the acoustic vibration. In the sound conductors shown in Figs. 14, 18 and 19, an acoustic wave absorbing layer 21 is disposed on the inner surface of the hollow body 48. The emitter 1 of the acoustic vibration wave 2 is placed in the body 48 at a predetermined angle and properly sealed. If aqueous solutions of acids or bases are used as the aqueous solution 49, the effective area of the emitter 1 has a coating which is chemically protective and acoustically non-absorbent (not shown in Figs. 14-20). The tetrafluoroethylene polymer can be used as such a coating.

In the sound conductor 3 shown in Fig. 15, which is similar to the sound conductor 3 shown in Fig. 4, a part of this sound conductor in which the emitter 1 is placed is made a hollow body 50 filled with an aqueous solution 51 of a compound selected from Table 3. the wall 4 of the tank 5 is made of a compound selected from Table 2.

The sound conductor 3 shown in Fig. 16, which is also similar to the sound conductor 3 shown in Fig. 4, has a hollow body 52 filled with an aqueous solution 53 of the compound selected from Table 3, the portion of the sound conductor in which the emitter 1 is placed. from the substance selected in Table 2.

24 6 3 3 0 0

In the sound conductor 3 shown in Fig. 17, which is also similar to the sound conductor shown in Fig. 4, both parts of the sound conductor 3 have separate bodies 50 and 52 filled with aqueous solutions 51 and 53, in which the sound wave has different propagation speeds and C, .. Both parts of the sound conductor 3 is separated by an acoustically conductive partition 54 having a radius of curvature R as determined by formula (3). A part of a hollow cylinder having an inner surface curvature radius R and made of a tetrafluoroethylene polymer can be used as a partition. The thickness of the partition 54 is selected to be an order of magnitude smaller than the length of the acoustic vibration wave 2.

In the contact portions of the sound conductors 3 shown in Figs. 16 and 17, the inner surfaces of the hollow bodies 52 are also coated with a layer 21 of a substance which absorbs sound waves.

The audio conductors 3 shown in Figs. 18, 19 and 20 are similar to the audio conductors 3 of the embodiments shown in Figs. 6, 11 and 12. The audio conductors form a hollow body 48 filled with an aqueous solution 49 of the compound selected from Table 3, as in the embodiments described above.

All of the above embodiments of the device can be successfully used to define liquid-liquid interfaces.

The method for determining the gas-liquid or liquid-liquid interface in single-layer containers is implemented with the embodiments of the device described above as follows.

A wave 2 of acoustic vibration is generated by means of the emitter 1 (Figs. 1, 2, 3) and the wave is introduced by a sound conductor 3 touching the wall 4 of the single-layer container 5 to said container 5 filled with two substances 6 and 7 (Fig. 1). The wave 2 is fed to a part 9 of the tank 5 located at a predetermined height and the presence of the interface 8 at this height is monitored by the proposed device.

Before introducing the acoustic vibration wave 2 into the container 5, the chest of the acoustic vibration wave 2 in the sound guide 3 is directed at a sharp or obtuse angle Θ (Fig. 3) with respect to the wall 4 of the single-layer container 5 and said vibration , determined by the direction of propagation of the acoustic oscillation wave 2 and its angle of incidence Θ. In the embodiments of the device shown in Figures 3-20, the angle Θ between the parallel of the acoustic vibration wave 2 and the direction of propagation of the excited mechanical vibration 10 is always sharp. The angle Θ can be obtuse under a completely defined condition, namely when the excited mechanical vibration 10 propagates in the opposite direction · as illustrated in Figures 3-20.

When the acoustic vibration wave 2 is directed, its velocity Cy along the wall 4 of the container 5 is set approximately equal to the propagation speed C of the mechanical vibration 10 along said wall 4: C = - ^ C '(12) 7' »where Cg is the propagation velocity of the acoustic vibration wave 2 in the audio conductor 3.

The required value Cy of the velocity of the wave 2, 13 is set appropriately by selecting the value of the input angle Θ and the substance of the sound conductor 3. The angle of entry of the acoustic vibration wave 2 into the wall 4 of the container 5 corresponds to the angle of inclination of the effective area 18 of the sound conductor 3 with respect to the contact area 19 touching its wall 4.

The emitter 1 is excited by an electrical oscillation which is either continuous or pulse amplitude modulated and which is produced by a generator 14.

As the mechanical vibrations 10 pass through the wall 4 of the long container 5, they experience an amplitude damping, the magnitude of which depends on the acoustic impedance of the substance 16 which contacts the inner surface of the vibrating part 9 of the wall. If this substance is gaseous, the amplitude attenuation is at a minimum; in the case where the substance is liquid, the amplitude attenuation is at a maximum. If there are two liquids in the tank 5, the damping of the mechanical vibration is higher for a liquid with a higher axial impedance.

When the mechanical vibration 10 enters the location area of the sound conductor 11, it becomes a partially converted acoustic wave 13 which propagates to the sound conductor 11 at an angle jf_ _ g to the contact area 19. this means that the oscillation propagates in the normal direction of the effective area 18 2 in which the receiver 12 is located. Said 26 63300 receiver converts the wave 13 into electrical signals having an amplitude proportional to the amplitude of the mechanical vibrations 10 in the location zone of the audio conductor 11. Electrical signals from the receiver 12 come to the input of the amplifier 15. The amplified electrical signals carrying information concerning the amount of damping of the mechanical vibrations 10 in the wall H part 9 of the container 5 and consequently the information about the interface 8 (Fig. 1) arrive at the measuring device (recording device 17 (Fig. 3)). an amplitude of electrical signals proportional to the amplitude of the acoustic wave 13 (Fig. 3) converted from mechanical vibrations 10 propagating along the wall 4 of the container 5.

In particular, if the amplitude of the measured electrical signals is at a maximum, the gas-liquid interface 8 (Fig. 1) is below the portion 9; if the amplitude is at a minimum, the interface is above said wall portion. When the monitored interface 8 is a liquid-liquid interface, the cases discussed above are relevant for the liquid with a lower acoustic impedance than the other.

The abrupt change in the amplitude of the electrical signals to be measured indicates that the interface 8 is at the level of the oscillating part 9 of the wall 5 of the tank 5 when the acoustic wave emitter 1 and the receiver 12 are mounted on said part by means of sound conductors 3. This change in amplitude can be registered automatically by a recording mechanism or a relay block in the measuring device 17 (Fig. 3), depending on its structure.

The method described above for monitoring the gas-liquid or liquid-liquid interface is technologically simple and enables efficient monitoring when the cross-section of the wall 4 of the container 5 is constant. The change in said cross-section changes the propagation speed C of the mechanical vibrations 10 along the wall 4 and therefore interferes with the similarity between the propagation speed C of said mechanical vibrations and the velocity C of the bead caused by the acoustic vibration wave 2? between. This in turn causes a decrease in the amplitude of the mechanical vibrations 10 excited in the wall 4, and consequently in the amplitude of the informative electrical signal, which leads to monitoring errors.

In order to reduce such errors, a method for determining the gas-liquid or liquid-liquid interface by means of the device shown in Figure 3 must be used in conjunction with the embodiments of the audio conductors shown in Figures 4-9.

According to a first embodiment of the method, the part 9 of the wall 4 of the single-layer container 5 is excited by a divergent or convergent wave 2 of acoustic vibrations, the maximum and minimum input angles of said wave 2 and O 2 are selected from formula (2). For each wall thickness 4 (Fig. 4) in the range d1-d2 and for the corresponding rates of mechanical vibrations 10 in the range C 1 -C 2, there is an incidence angle Θ which is in the range and satisfies condition (1) for optimal excitation of the mechanical vibrations 10.

The divergent wave in the angular range θ2 is formed from the wave 2 of the emitter 1 by a cylindrical contact surface 24 of the two parts 22 and 23 of the sound conductor 3 having a radius of curvature R. The central radius 25 of the wave 2 passes through the surface 24 without bending and enters the wall 4 at an angle Θ the same as the inclination of the effective area 18 of the sound conductor 3 with respect to the contact area 19 of said sound conductor.

The side rays 26 and 27 of this wave 2 refract because they do not hit the surface 24 perpendicularly but at an angle kul to the normal of the surface. This angle £ is determined by the formula:

Jlin t- - (13)

2R

where A is the length of the effective region 18 of the audio conductor 3 (or emitter 1) and respectively on the receiver 12 side (Figures 1 and 3) in a plane passing through a line coinciding with the direction of mechanical vibrations propagated in the wall 4 of the container 5 .

After bending on the cylindrical surface 24 (Fig. 4), the rays 26 and 27 propagate in the second part 23 of the sound conductor 3 at an angle ^ to the normal of this region 24: n Cg n AC ^ = aro Yin (j- £ in i) = aro {fin (11 () where and are the propagation velocities of the acoustic vibration wave 2 in the sound guide parts 22 and 23, and these beams enter the wall 4 at the corners and are determined by the formulas: 28 63300 θ = θ - arc Jdn - + arc tin - ~ 2R 2C4 = (15)

ACj- _ A

8? = 8 - arc ^ in - + arc Yin - (16)

0 2C [+ R ° 2R

In order for the maximum and minimum angles of the wave after refraction 8 and 82 to correspond to the required divergence or convergence of the wave, the radius of curvature R of the cylindrical contact surface 24 between the portions 22 and 23 in both sound conductors 3 and 11 (Fig. 3) is selected from formula (3) (15) and (16). Figure 4 shows an example of divergence of wave 2 when If C4 <C5 »is wave 2 convergent. In the implementation of the first embodiment of the method described above, in which the errors related to the reduction of the informative electrical signal are eliminated, in the given embodiment of the device, making the audio conductors 3 and 11 provided with a cylindrical contact surface 24 is quite complicated. A simpler structure for the audio conductors 3, 11 is given in the second embodiment of the device shown in Figures 6 and 7.

In this embodiment, the audio conductors 3, 11 have a cylindrical effective region 18 while the emitter 1 of the acoustic wave 2 and 13 and the receiver 12 (Fig. 3) have similar effective regions as the effective regions of the audio conductors 3, 11, which causes the divergence of the acoustic vibrations wave 2, 13. or convergence. The divergence of wave 2 occurs when the effective region 18 of the sound conductor 3 is convex and convergence (shown in Fig. 6) occurs when this region is concave. The central radius 25 of the wave 2 enters the wall 4 at an angle Θ which is equal to the angle between the tangent drawn in the middle of the effective area 18 and the contact area 19 of the sound conductor 3. The side radii 26 and 27 of the wave 2 enter the wall 2 at angles 0 ^ and Θ2, respectively, which are larger or smaller than the angle Θ by the angular value determined by the formula (13): θ, = Θ + arc iin - (17)

1 ° 2R

8 = 0- arc <£ in - 2R (18) 29 63300

In order for the angles ^1 and θ2 determined from these formulas (17) and (18) to satisfy the required convergence or divergence condition (2) of wave 2, the length A (or emitter 1 and receiver 12, respectively) must be selected by formula (4). ).

The device shown in Figures 6 and 7 makes it possible to reduce the above-mentioned errors in monitoring the interface 8 (Figure 1) by making the effective areas 18 of the audio conductors 3, 11 cylindrical without limiting the length of the acoustic vibrations wave 2.

The embodiment of the audio conductor 3 of the device shown in Figs. 8 and 9 is simpler than the embodiments shown above, but causes certain limitations in the ac. / / _ _. In this embodiment of the device, the minimum distance between the effective area 18 of the audio conductor 3 and the contact area 19 is selected according to formula (6) so that the length of the side beam 27 exceeds the length of the Fresnel zone B of the acoustic field of the emitter 1, which zone 2 has a non-divergent planar chest. the planar chest 28 of the wave 2 of this zone transforms into a partially spherical chest with a divergent bundle of acoustic rays 26 and 27, the side beams entering the wall 4 at angles 8 ^ and θ2 »where 8 ^ is smaller and θ2 larger than the center angle of the beam 25.

At a sufficiently large distance from the boundary of the Fresnel zone, the divergence angle of wave 2 is determined from the orientation pattern of emitter 1, and almost all the energy of acoustic emission is limited to this di-divergence angle of: h * 8, - 80 = 1.4 arc λιη - 1 1 UA, (19) where k ^ is a coefficient determined by the shape of the effective area 18 of the sound conductor 3 and is e.g. 1.22 for a spherical and 1 for a rectangular shape. Then the angles 8 ^ and θ2 are determined from the following equations: kl λ.

Θ, = 8 + 0.7 arc £ in - 1 U A, (20) k “3 θ0 = θ - 0.7 arc Cin —- 1 U A (21) 30 63300

The solution of the set of equations (2), (20) and (21) gives the ratio (5) effective area 18 for length A and wavelength \, which ratio ensures the required divergence of wave 2 and consequently the optimal excitation of the wall 5 of the tank 5 wall part 9 (Fig. 3). in the range of 10 propagation speeds of vibrations ·

The device shown in Fig. 3 and its embodiments, equipped with the various audio conductors 3 shown in Figs. 4-9, have a simple electrical channel that allows monitoring when the amplitude instability (with respect to time) of the generator 14 electric vibrations is small, said vibrations being used 1 to wake up (activate). Changes in the amplitude of the electrical oscillations of the generator 14 require periodic repositioning of the measuring device 17 or a change in the gain of the amplifier 15, which affects the efficiency and stability of the monitoring.

The use of the device shown in Figure 10 can improve both efficiency and stability in gas-liquid or liquid-liquid interface monitoring.

In this embodiment, the reference electrical signal is generated in analog or discrete form by the shaper 29 from the electrical vibrations of the generator 14; the informative electrical signal is formed in the same form by the former 31 from the electrical signals of the amplifier 15; said reference and informative electrical signals are compared with each other in the comparison block 30. The output signal of the comparison block 30, which is proportional to the difference or ratio of comparable signals, goes to the measuring device 17. Since the amplitude instability of the is virtually independent of said instability.

The described device together with the sound conductors (Figs. 4-9) is very effective in the case where the amplitude of the electric vibrations of the generator 14 is differently unstable and when the propagation speed C of the mechanical vibrations excited in the wall 5 of the tank 5 changes in the range C · ^ - C ^ the amplitude of the mechanical vibrations 10 (Fig. 10) changes when the conditions of entry of the wave 2 into the wall 4 via the contact surface 19 of the sound conductor 3 change during stationary operation of the device or during rapid adjustment of the interface 8 (Fig. 1) 31 63300. Such changes in input conditions can be caused, for example, by different thickness of contact grease between the contact area 19 of the audio conductors 3 and 11 and the wall 4 of the container 5, roughness of the wall 4 during rapid adjustment, and cracking, detachment and partial destruction of the contact layer 5 within the stationary supervision of the wall 4 interface. These variations require intermittent resetting of the informative electrical signal shaper 31, and resetting moments can cause significant errors in interface monitoring.

It is possible to reduce such errors by using a gas-liquid or liquid-liquid interface monitoring method implemented utilizing the devices shown in Figures 11 and 12.

According to this interface monitoring method, secondary mechanical vibrations 38 are additionally excited to the portion 4 of the wall 4 of the container 5 by a wave 34 of acoustic vibrations whose mechanical vibration damping is different from the damping of mechanical vibrations 10 excited by the primary wave 2. In this case, the state changes 4 and the change in the amplitude of the electrical vibrations of the generator 14 cause similar changes in the amplitudes of the primary and secondary mechanical vibrations 10, 38. Similarly, a change in the parameters of the contact area 19 of the audio conductor 11 causes a similar change in the sound wave 13 converted from mechanical vibrations 10 primarily excited in wall 4 and the sound wave 36 converted from mechanical vibrations 38 secondary excited in wall 4. The interface 8 (Fig. 1) between the mechanical vibrations 10 (Figs. 11 and 12) and 38, which were excited by the primary and secondary waves 2 and 34 of the acoustic vibration, regardless of changes in the conditions affected by the input of the waves 2 and 34 to the contact area of the audio conductor 3 19 and the modification caused by the contact area 19 of the audio conductor 11.

In the device shown in Fig. 11, the wave 34 is applied to the wall 4 for the secondary excitation of the mechanical vibrations 38 by means of an additional emitter 33. Said additional emitter is oriented in such a way that its effective region coinciding with the effective additional region 32 of the audio conductor 3 forms an angle with the contact region 19, which angle is selected from formula (7), which satisfies the equatorial wave 34 velocity and mechanical oscillations. Between 38 speeds. Wave 34 is applied to the wall 4 at said angle fr. The acoustic wave 13, which is converted primarily from the excited mechanical vibrations 10, propagates at an angle Θ with respect to the normal of the contact area 19 and enters the main receiver 12 along the normal of its effective area. The acoustic wave 36, which is converted secondary to the mechanical vibrations 38 excited in the wall 4, propagates in the sound conductor 11 at an angle fr with respect to the normal of its contact area and enters the auxiliary receiver 35 along the normal of its effective area.

From the electrical signals of the main receiver 12 which have passed through the main amplifier 15, the shaper 31 generates (in discrete or analogous form) an infrared electrical signal having an amplitude proportional to the amplitude of the primary excited mechanical oscillations 10 entering the location zone of the audio conductor 11. The second shaper 29 generates a reference electrical signal from the electrical signals coming from the auxiliary receiver 35 and passing through the auxiliary amplifier 37, the amplitude of this reference electrical signal being proportional to the amplitude of the mechanical signals 38 secondary excited at the location of the audio line 11. Both the reference electrical signal and the informative electrical signal generated by the molds 29 and 31 are equally affected by the instabilities that occur in the contact area 19 of the audio conductor 3 when the acoustic vibration waves 2 and 34 are introduced into and 36. As a result, the output signal of the reference block 30 formed of the informative signal and the reference signal coming to this block is proportional to the relationship between these signals and is not dependent on the above-mentioned instabilities.

Since the mechanical vibrations 10, 38 produced by the primary and secondary excitation have different damping in the wall 4 of the container 5 caused by their partial leakage of energy into the contact surface 16 of the vibrating part 9 of the wall 4, the output signal of the reference block 30 provides an undeniable information interface 8 (Fig. 1). ) between substances 6 and 7 in the controlled tank 5 and its information is recorded by the recording equipment 17.

63300

The connection of the input zones of the main and auxiliary waves 2, 34 of the acoustic oscillations in the contact area 19 of the audio conductor 3 and the conversion zones of the main and auxiliary acoustic waves 13, 36 converted from the primary and secondary mechanical vibrations 10, 38 in the contact area 19 of the mains between the projections of the centers of the additional areas 18, 32 in the contact area 19 and the heights and Hj from the contact area 19 to these centers according to the formula (8).

Although the present device effectively eliminates the effect of the above-mentioned instabilities and the electronic channel of the device is relatively simple, changes in the converter characteristics of the emitters are possible and this can lead to corresponding errors.

Such errors can be reduced by implementing the described method using the device shown in Figure 12 with one emitter 1, one receiver 12 and a more complex electronic channel. In this case, the additional wave 34 introduced at an angle to the wall 4 and used to secondary excite the mechanical vibrations 38 in said wall 4 is generated by reflecting part of the acoustic vibration wave 40 of the emitter 1 from the reflection region 39 of the sound conductor 3 forming an angular region 18 7) and (9) are defined as 7Γ +] f-9. The second part of the wave 2 of the emitter 1 is introduced into the wall 4 at an angle Θ 2 and is used for the primary excitation of mechanical vibrations 10 in the wall 4 inside the part 9. In the sound conductor 11, the primary excited mechanical vibrations 10 are converted into a main acoustic wave 13 propagating at an angle Θ with respect to the normal of the contact area 19 of this sound conductor. The mechanical vibrations 38 excited from the secondary are converted in the audio conductor 11 into an acoustic wave 36, which also propagates at an angle to the normal of the contact area 19 towards the reflection area 39. The wave 36 is reflected from said reflection area and enters the receiver 12 along the normal of this effective area.

The secondary excited mechanical vibrations 38 have a propagation velocity Cg along the wall 4 which is different from the velocity C of the primary excited mechanical vibrations 10 (Cg ~ ^ · C in the embodiment of the device shown in Fig. 12). Therefore, when the propagation path of the mechanical vibrations 10 along the wall 4 substantially exceeds the parallel of the emitted wave, the main and auxiliary acoustic waves 13 and 41 arrive at the receiver 12 with a time shift relative to each other, which substantially exceeds the time amplitude pulse amplitude from the generator 14 to the emitter 1. * -1. As a result, the electrical main and auxiliary pulse signals of the receiver 12, the amplitudes of which are relative to the primary and secondary excited mechanical oscillations 10 and 38, become separated in time.

The pulse signals of the receiver 12 come through a common amplifier 15 to the inputs of the selection blocks 42 and 43, the monitored inputs of the blocks of which are fed by selection pulses from the output of the shaper 44. The selection pulses entering selection block 42 correspond to the time position of the main pulse signal and the selection pulses entering block 43 correspond to the time position of the reference pulse signal.

The main electrical and auxiliary signals separated in blocks 42 and 43 are fed to a shaper 31 arranged to shape an informative electrical signal and a shaper 29 arranged to shape an electrical reference signal and then fed to the inputs of a reference block 30. An output of this block information about the monitored interface, enters the recording device 17.

The method described above for monitoring the interface in single-layer tanks provides very accurate and stable monitoring over long periods of operation. At the same time, this method makes it possible to reduce errors due to instabilities that occur when a wave of acoustic vibrations is introduced into the tank wall and when mechanical vibrations generated in the tank wall are converted to an acoustic wave in the contact area of the audio conductor. However, errors may occur in the method described above due to changes in the frequency of mechanical vibrations in the vibrated portion of the container wall, which errors are related to different locations of the interface in this container.

These errors can be reduced when the method according to the present invention for monitoring the gas-liquid or liquid-liquid interface in single-layer tanks is implemented using the device shown in Fig. 13.

In this method, part 9 of the wall 4 of the tank 5 is vibratically vibrated by a pulse wave 2 of acoustic vibrations, the wave spectrum of which is selected from the range exceeding the frequency range of mechanical vibrations of the wall 5 of the tank 5 when the interface 8 (Fig. 1) is found between 6 and 7. positions relative to the oscillating portion 9 of the wall 4 (Fig. 13). The broad-spectrum pulses produced by the shaper 45 and passed through the power amplifier 46 act on the emitter 1. These pulses have the shape and duration * LQ »of rectangular video pulses (square pulses) determined by formula (10). As a result, the emitter 1 emits spectral ultrasonic vibrations in the sound conductor 3, covering all the frequencies of the mechanical vibrations 10 of the wall 4 when the interface 8 (Fig. 1) is found at different positions.

The pulse signal from the receiver 12, which signal at said receiver is converted from an acoustic wave 13 (Fig. 13), which in turn is converted from mechanical oscillations 10 coming into the contact area of the audio conductor 11, has an amplitude of electrical oscillations equal to that of the received pulse signal. acoustic pulse wave 13) depending on the monitored interface 8 (Fig. 1). In addition, the frequency f of the filling electrical vibrations depends on the type of substance 16 (Fig. 13) in contact with the vibrating part 9 of the wall 4 of the container 5.

Said frequency f is registered in a block 47 adapted to measure the frequency of the electrical signal, the signal being input to said block 47 from a receiver 12 via an amplifier 15.

The frequency thus measured is used to determine the type of liquid (characterized, for example, by its acoustic impedance value) when the interface 8 (Fig. 1) is located above or below the vibrating part 9 of the wall 4 (Fig. 13) of the container 5.

The informative signal is formed in a former 31 adapted to form an informative electrical signal from the pulse signals of the receiver supplied to said former 31 via an amplifier 15. The amplitude of the informative signal thus generated is relative to the amplitude of the pulse signals. The reference electrical signal is formed in the shaper 29 from video pulses taken from the output of the power amplifier 46. Said reference signal and informative electrical signal enter the reference block 30. The output signal of the block 30 of this 63300 provides information about the monitored interface 8 (Fig. 1) and this is registered by the recording device 17 (Fig. 13).

The embodiment of the method described above effectively reduces the effect of changes in the frequency of mechanical vibrations caused by different positions of the monitored interface, and allows additional control of the type of liquid when the cross-section of the wall part to be vibrated is constant. However, errors can occur when said cross-section varies considerably, which causes a change in the frequency of the mechanical vibrations over a wider range than the case where the position of the interface in the container changes.

These errors are reduced when the method of monitoring the gas-liquid or liquid-liquid interface according to the present invention is implemented with a device also shown in Fig. 13.

According to this method, the portion 9 of the wall 4 of the container 5 is periodically vibrated by a pulsed wave 2 of acoustic vibrations, the relative width of the wave spectrum selected according to formula (11) equal to or greater than the relative change in the thickness of the vibrating portion 9 of the wall 5 of the container 5. This is achieved by the sound conductors 3 and 11 being made of fused quartz or porcelain or silicon or lead or tin or lead-tin alloys having an acoustic impedance in the range of 0.3 to 1.7 times the acoustic impedance of the emitter 1 and receiver 12 for the acoustic wave. The materials from which the audio conductors are made are defined in Table 2.

Such a structure of the sound conductors 3 and 11 provides acoustic attenuation of the emitter 1 and the receiver 12, respectively, broadening the limits of the emission and reception spectra of the acoustic vibration waves 2 and 13. The decrease in the acoustic impedance of the audio conductors 3 and 11, which depends on the material of the audio conductors, relative to the acoustic impedance of the emitter 1 and the receiver 12, reduces the width of the spectrum. The type of material of the audio conductors 3 and 11 and their impedance (see Table 2), respectively, are selected according to the spectral width required by formula (11).

The method presented here ensures the control of the interface and the type of liquid when the interface is located above or below the vibrating wall part of the container (in the case of a gas-liquid system, the interface is above this wall part). However, monitoring errors can occur due to temperature fluctuations. The value of these errors is usually determined by the temperature dependence of the propagation speed of the acoustic vibration wave in the audio conductors.

Temperature errors can be greatly reduced by using the gas-liquid or liquid-liquid interface monitoring devices shown in Figures 3-13 with the audio conductors in accordance with Figures 14-20.

The reduction in temperature errors is obtained by making the sound conductors 3 and 11 based on aqueous solutions of alcohols or alkalis or salts of acids or inorganic acids, in which the dependence of the speed of acoustic wave 2, 13 on temperature t is almost parabolic C3 »C3 make Λ -« - »„)? >. (22) where C3 ^ is the maximum propagation speed of wave 2, 13 in aqueous solution when t = t.

o

The concentration q of the solution is chosen so that the maximum value of the propagation speed Cg j ^ g is in the range of the average temperature t of the wall 4 of the tank 5. As a result, the speed of the acoustic wave in the sound conductor 3 in the operating temperature range varies quite little. For example, when the temperature variations are -20 ° C from the mean t, the speed varies by a maximum of 0.6%. This substantially increases the accuracy of the interface control.

The above-mentioned method for controlling the gas-liquid or liquid-liquid interface in single-layer tanks with the devices shown in Figures 3-20 provides very efficient non-contact automatic control of interfaces in tanks in various technological processes in metallurgical, ore beneficiation, chemical, petrochemical, nutrient and other industries.

Claims (10)

38 63300 An apparatus for determining the position of an interface between two substances having different acoustic properties in a tank, a sound source connected to a point on the tank wall for conducting an acoustic wave to the tank wall, a sound receiver connected to another point on the tank wall to receive a wave passing through the tank wall, and means by determining the amplitude of the acoustic wave received by the sound receiver as a characteristic of the interface, characterized by a combination of the following features: a) the sound source (1) is connected to the tank wall (4) via a first sound conductor (3) leading the acoustic wave (2) ^ to the wall of the tank, in which the mechanical vibrations (10) propagate in the direction determined by the direction and angle of incidence of the acoustic wave and at a speed approximately equal to the speed of propagation of the acoustic wave in the tank wall b) the sound receiver (12) receives via the second sound conductor (11) an acoustic wave (13), the amplitude of which determines the height of the interface (8). Device according to Claim 1, characterized in that a) in each sound conductor (3; 11) the contact surface (19) with the container wall (14) and its respective sound source surface (18) are at an angle Θ to each other defined by the formula Θ (b) and the sound conductors are made of a material in which the rate of propagation of the acoustic waves (2 and 13) is less than the rate of propagation of the mechanical vibrations (10) in the wall of the tank. Device according to Claim 1 or 2, characterized in that, in the event that the cross-section of the tank wall (4) varies, the audio conductors (3 and 11) are made of two parts (22 and 23) whose materials differ from those of the acoustic waves ( 2, 13) and having a cylindrical contact surface (24) with an axis of symmetry in the plane of the axes of the sound source (1), the sound receiver (12) and perpendicular to these axes 39 63300, the radius R of the contact surfaces fulfilling the requirement R <c + C ^ "cT = c 'A ct? ® 1 2 Device according to Claim 1 or 2, characterized in that a) in the event that the cross-section of the container wall varies, the effective areas (18) of the sound conductors (3, 11) are cylindrical, the radius of curvature R being determined by the formula Vc2 E <2 ( crc2t · A <= tg Θ b) the sound source (1) and the sound receiver (12) are made so that their effective areas are the same as the effective areas of the sound conductors (18). Device according to claim 1 or 2, characterized in that a) in case the cross-section of the container wall varies, the length A of the effective area (18) of the sound conductors (3, 11) in a plane defined by the normal area of said effective surface and the direction of propagation of the mechanical vibrations (10) generated in the tank wall is determined by the formula VC2 A <K w - r- -. λ. ctg Θ 2 b) the minimum distance Hmin between the effective area (18) and the contact area (19) of the sound conductors over the tank wall is determined by the formula a2 «min> 4Γ COS 0 Device according to one of Claims 1 to 5, characterized in that the sound conductors (3, 11) are, if necessary, made of fused quartz or porcelain or silicate glass or tin or lead or tin-lead alloys with an acoustic impedance in the range of 0.3 to 1.7 times the sound source. (1) the acoustic impedance for the transmitted acoustic wave (2) and the acoustic impedance of the sound receiver (12) for the received acoustic wave (13). 1.0 63300 Device according to one of Claims 1 to 5, characterized in that the sound conductors (3, 11) are made on the basis of aqueous solutions of alcohols or alkalis or acids or salts of inorganic acids. Device according to one of Claims 1 to 7, characterized in that a) the sound guide (3, 11) has additional effective areas (32) which form an angle-with respect to their contact surface (19) with the container wall (4), b) an additional sound source (33) for transmitting acoustic waves (34) and an additional sound receiver (35) for receiving acoustic waves (36), which sound source (33) is connected to the same electrical vibration generator (14), are mounted on the additional effective areas of the sound conductors (3, 11) as the first audio source (1). Device according to one of Claims 1 to 7, characterized in that the sound conductor 11a (3, 11) is a reflection region (39) for repeatedly transmitted acoustic waves (34, 36), which region forms an angle β with their effective region (18). Device according to one of Claims 1 to 9, characterized in that an electrical feedback circuit is formed between the sound source (1) and the sound receiver (12), in which circuit a comparator (30) is used to control the position of the substance interface (8) in the tank (5). 41 63300