EP0618847A1

EP0618847A1 - Process and device for acoustically irradiating and transferring vibrations to an acoustic irradiation fluid containing particles.

Info

Publication number: EP0618847A1
Application number: EP93921774A
Authority: EP
Inventors: Franz Gaehler; Urs Keller; Roland Meier
Original assignee: Sofima AG
Current assignee: Sofima AG
Priority date: 1992-10-08
Filing date: 1993-10-08
Publication date: 1994-10-12
Anticipated expiration: 2013-10-08
Also published as: WO1994008732A1; DE59302055D1; AU5105993A; EP0618847B1; JPH07501981A

Abstract

L'invention a pour objet un procédé pour la production de vibrations et leur transmission à un liquide soumis aux ultrasons (11), selon lequel les ondes d'ultrasons sont produites par une sonde acoustique (2) munie d'un transformateur acoustique (6) et d'un résonateur (3) fixé à ce transformateur. Le résonateur (3) est entouré, conformément à l'invention, par la paroi d'un compartiment (9), l'espace intermédiaire (7) compris entre le résonateur (3) et la paroi (9) étant rempli d'un liquide de transfert (15). Ce dernier transmet les vibrations de la surface du résonateur (3) au liquide (11) entourant la paroi (9). Le résonateur (3) peut être mis en fonctionnement indépendamment des propriétés d'amortissement du liquide soumis aux ultrasons (11) et des particules qu'il contient à soumettre aux ultrasons.The subject of the invention is a method for the production of vibrations and their transmission to a liquid subjected to ultrasound (11), according to which the ultrasound waves are produced by an acoustic probe (2) provided with an acoustic transformer (6 ) and a resonator (3) fixed to this transformer. The resonator (3) is surrounded, in accordance with the invention, by the wall of a compartment (9), the intermediate space (7) comprised between the resonator (3) and the wall (9) being filled with a transfer liquid (15). The latter transmits the vibrations of the surface of the resonator (3) to the liquid (11) surrounding the wall (9). The resonator (3) can be operated independently of the damping properties of the ultrasonic liquid (11) and of the particles it contains to be ultrasonicated.

Description

Method and device for sonication and for the transmission of vibrations to a sonication liquid containing particles

The invention relates to a method and a device for sonication and for the transmission of vibrations to a sonication liquid containing particles as per one of claims 1, 7 and 21.

For many years, ultrasonic cleaning systems have been used for cleaning the surfaces of jewelry, but also machine parts, which consist of a container containing a cleaning liquid, an ultrasonic generator and one or more sound transducers, which are attached to the outside of the container walls and vibrate move and transfer the vibrations to the liquid.

It was recognized early on as a disadvantage that the sound transducers have poor adaptability to the load, which is composed of the container, the cleaning liquid or the coupling medium and the objects immersed therein for cleaning. The physical conditions, such as the working frequency, the transmission behavior of the container, the damping of the coupling fluid and the material to be cleaned, also set limits to the dimensions of the cleaning systems.

From EP-Bl-0044800 it is known that a typical pie zoelectric sound transducer for a working frequency of 20 kHz has a length of approximately 100 mm and a lateral dimension of approximately 65 mm. Such a sound transducer can only radiate 2 to 6% of the energy to the coupling medium; the rest causes heat in the transducer, which is dissipated and / or only allows short switch-on times. From the cited document it is also known that another factor stands in the way of a good adaptation of the load to the coupling liquid and the objects to be cleaned immersed therein. The sound power radiated per unit area cannot be increased arbitrarily, because the cavitation partially decouples the sound transducer from the coupling fluid. These findings have resulted in a large number of sound transducers having to be installed on the tank bottoms in larger cleaning systems. This leads to high investments and correspondingly high operating costs. Despite this improvement, when sonicating a suspension into which a large number of particles to be treated have been introduced, it is insufficient to introduce the sound energy required for cleaning these particles into the suspension, since the attenuation caused by these particles greatly reduces the propagation of the sound waves or prevented.

A measuring instrument for measuring the characteristics of liquids (US-A-3, 680,841) is also known from the European search report. A sonication device immersed in a container filled with liquid is intended to prevent precipitation from forming on the areas of measuring electrodes immersed in the liquid. To protect against the aggressiveness of the liquid to be characterized, eg acid, is encased in the transducer. In order to transmit the vibrations of the vibrator consisting of an electrical sound transducer to the protective sheath surrounding it, a liquid is filled in the latter. This protective jacket acts as a resonator and transmits the ultrasound waves directly to the liquid to be measured. According to the US specification, it should be possible with the vibrator to prevent deposits on the two electrodes with low energy, so that, for example, the quality of a pH measurement can always be constant, even if the liquid is partially crystallized. Since the sound transducer is surrounded by a jacket, it can be used directly in hot and corrosive liquids and cooled by the liquid. The liquid, for example, to be measured for its pH value, contains no suspended particles to be cleaned, which have a dampening effect on the propagation of the sound waves. Problems with the vibrator. this application does not occur in order to start up or maintain its operation. It is not possible to use the probe known from US Pat. No. 3,680,841 for the sonication of attenuation-rich sonication media.

The use of the pipe vibrator known from EP-Bl-0044800 for the sonication of powder, granular or other-shaped products suspended in the coupling liquid and contaminated with deposits has not proven to be possible if the percentage of products to be cleaned is related to the amount of Coupling fluid exceeds certain limits. In most cases it succeeds at all not to vibrate the resonator within the liquid, since the damping of the coupling liquid together with the products to be cleaned contained therein is too great. A substantial reduction in the percentage of the product to be cleaned in the liquid in order to reduce the damping is not desirable for reasons of productivity and cost. For this reason, no systems for large-scale sonication of free-flowing bulk goods, such as blasting media, foundry sand etc., have been put into practice to date.

This problem is clearly known from FR-PS-1.212.496. There, an attempt is made to expose only a small amount of material to be sonicated to the sound waves of a sonic device in a very small sonication container. Since the detached contaminants are lighter, but the cleaned particles are heavier than the sonication liquid, they are separated naturally and no additional devices or influences are required. In addition to the very low possible output of such a system, it can e.g. for cleaning abrasives in which e.g. Corundum and heavy metal contaminants must be separated, are not used. The same problems also occur when cleaning foundry sand.

From European patent application No. 91115504.2 a method for the treatment of bulk goods is known, in which the contamination of the foundry sand is to be removed with ultrasound. Tests have shown, however, that even an economically uninteresting small one Concentration of bulk material in the sonication liquid the sound probe can no longer be started.

It has also been shown that the perfect detachment alone does not allow the expected clear separation of the components, because the deposits tend to stick again.

The object of the present invention is to provide a method and a device for generating sound waves and for removing particles present in a sound reinforcement from their adhering deposits or impurities.

This object is achieved by a method and a device according to the features of claims 1, 7 and 21.

Surprisingly, with the method and the device according to the invention, the sound probe or the resonator succeeds despite the loss of energy through the additional transmission media, which prevent the contact of the resonator with the sonication fluid and the particles to be cleaned, which are essentially independent of the damping properties of the particles and the particle-containing sonication and coupling fluid. The compartment wall used to separate the transmission medium is set in motion by the sound waves emitted by the resonator and transmits them to the particles to be sonicated.

When using a resonator with a surface structure, the vibrations will decrease - 6 -

sent from the resonator crossing each other in all directions. In the case of a resonator with elevations in the form of rods, humps, etc., the vibrations are also emitted to the sonication fluid in all directions, so that the sound waves can cross in the sonication medium and thus also hit the particles to be sonicated from all sides.

If a compartment wall permeable to the coupling liquid is used, there is no need for an additional transmission fluid, and the sonication energy is transferred directly from the resonator into the protective flow or jacket which is located between the resonator and the compartment wall but is not particle-laden Sonication fluid introduced.

The invention is described below with reference to illustrated embodiments. Show it:

1 shows a longitudinal section through a

Public address device with a jacket-shaped

Compartment wall in a sound container, Figure 2 shows a longitudinal section through a

Public address device with a bag-shaped

Compartment wall, Figure 3 shows a longitudinal section through a

Public address device with a corrugated

Compartment wall, Figure 4 shows a longitudinal section through a

Public address device with a compartment wall provided with elevations, Figure 5 shows a longitudinal section through a

Public address device with a tubular Resonator and a compartment wall inserted therein, Figure 6 shows a longitudinal section through a

Public address device with a jacket produced by a flowing transmission fluid, FIG. 7 shows a longitudinal section through a

Public address device with a compartment wall and a container designed as an upflow classifier (partially shown as a section), FIG. 8 shows a longitudinal section through a

Public address device with a double-walled, liquid-permeable tube comprising the probe (partially shown as a half-section), FIG. 9 shows a longitudinal section through a pipe

Public address device according to FIG. 8 without a compartment wall separating the resonator and the acoustic fluid (partially shown as a half-section), FIG. 10 shows a longitudinal section through a

Public address system with a tubular and helical abbey. wall and with a centrifuge, Figure 11 shows a longitudinal section through a

Public address device with a tubular and helical compartment wall inserted into an upstream classification device. The public address device 1 according to the invention has a hollow or solid resonator 3 with a diameter d of, for example, 48.5 mm, which is connected to a sound transducer 6, which is shown only schematically in FIG. The sound transducer 6 is arranged outside the tube-shaped resonator 3 here and connected at the end to the latter. A magnetostrictive or a piezoelectric sound transducer 6 can be attached. The sound probe, designated as a whole by 2, is connected at its one end, which contains the sound transducer 6, to the wall 8 of a sound container 10 via flange 13. The resonator 3 can also have a shape other than a tubular geometric shape.

The sound transducer 6 is supplied with energy by a sound generator 16, which is likewise arranged outside the resonator 3 and the sound container 10, via the line 12.

To form an intermediate space 7, a jacket-shaped compartment wall 9 surrounds the resonator 3 in the first example. The compartment wall 9, with the resonator 3 arranged therein, is immersed in a sound reinforcement liquid 11 to be sonicated. The compartment wall 9, the diameter D of which is, for example, 85 mm, is at least partially vibration-connected to the resonator 3 via a transmission medium or a transmission liquid 15 located in the space between the surface of the resonator 3 and the inner surface of the compartment wall 9. The intermediate space 7 between the resonator 3 and the compartment wall 9 can thus be completely or partially filled with the transmission liquid 15, which transmits the vibrations initially transmitted from the resonator 3 to the transmission liquid 15 to the sonication liquid 11 and the particles 32 introduced therein and the particles thereon sedentary deposits 34 transfers (only a few shown in Figures 1 and 2). The compartment wall 9 can be used for indirect transmission be a closed vibratory body or a perforated body for direct transmission; it can also be designed in the form of a net or lattice or as a textile fabric and the passage of

Allow transfer liquid 15 or sonication liquid 11 without loading with sonicating and damping particles into the intermediate space 7 or in the opposite direction.

It is also possible to design only the bottom .18 of the compartment wall 9 to be liquid-permeable.

The compartment wall 9 consequently serves to create a low-damping zone between the resonator 3 and the sonication liquid 11 with the parts 32 contained therein.

In the case of a liquid-tight compartment wall 9, low-damping transmission liquid 15 can be used for the transmission of the vibrations generated at the resonator 3 to the compartment wall 9 water. The jacket-shaped compartment wall 9 can be made, for example, of metal, glass or plastic, with their

Natural resonance behavior is preferably adapted to the desired sound frequencies.

In the case of a liquid-permeable compartment wall 9, this acts as a sieve and the liquid present between the resonator 3 and the compartment wall 9 is in this case identical to the sonication liquid 11. The transmission of the vibrations from the resonator 3 to the particles to be sonicated now takes place in this embodiment of the invention directly through the particle-free sonication liquid 11 in contact with the resonator 3 and to a lesser extent also through the compartment wall 9. The vibratory compartment wall 9, which acts as a sound or vibration transmitter, can have a structured surface (FIG. 3). This enables the sound waves to be emitted in mutually intersecting directions. In a further embodiment of the invention according to FIG. 4, elevations or thorn-shaped or rod-shaped attachments 21 can be attached to the surface of the compartment wall, which also allow a confused radiation of the sound waves.

In the embodiment of the invention according to FIG. 2, the compartment wall 9 can alternatively have the shape of a bag consisting of a film or mesh in order to separate the transmission liquid 15 from the sonication liquid 11. The bag 17 can also be attached to the end of a compartment wall 9 which extends only over a partial length of the resonator 3.

In a second embodiment of the probe 102, the resonator 103 can be designed as a hollow body, in which the compartment wall 109 is inserted, forming an intermediate space 107 for the transmission liquid 115.

In the simplest embodiment according to FIG. 5, both the resonator 103 and the compartment wall 109 used in it are tubular. The sonication fluid 111 with the particles 132 to be sonicated is then located within the compartment wall 109, which can be set in motion by the transmission liquid 115. Direct contact between the surface of resonator 103 and the The sonication fluid 111 in the space 107 and the particles 132 therein does not take place. With this embodiment, a greater sound wave density is achieved in the sonication liquid 111. A liquid-tight or a liquid-permeable compartment wall 109 can also be used here.

In a third embodiment of the invention according to FIG. 6, a correspondingly guided introduction of transmission fluid 215 (shown as a helix) or particle-free

Sonication liquid a liquid antel are generated, which largely prevents direct contact of the particles 232 in the sonication liquid 211 with the resonator 203. Instead of the helical course of the flow of the transmission liquid 215, which is shown in FIG. 6, a flow of the transmission medium 215 running parallel to the longitudinal axis of the resonator 203 could also be generated (cf. also the embodiment according to FIG. 9).

In FIG. 7, the resonator 303 is arranged in a compartment wall 309 which is spherical in the lower region 324 and which is in contact with the resonator 303 through the transmission liquid 315. Outside of the cylindrical upper section 326 of the compartment wall 309, a guide wall 328 is arranged parallel to the latter, the lower end 330 of which ends at a distance from the spherical section 324 with the formation of a gap X. The container 310, in which the resonator 303 of the acoustic probe 302 is immersed, has a cylindrical configuration in the upper section. The contour of the container runs in the region of the spherical section 324 of the compartment wall 309 310 in sections approximately parallel to the spherical section 324. The spherical section 324 can be arranged independently of the compartment wall 309 below this (no illustration). The container 310 ends in a line 312 below.

The combination of the described features forms an upflow classifier, in which particles 332 of different sizes and / or formed, which are suspended in the sonication liquid 311 and have been released by the sound probe 302, can be separated and discharged separately. The separation is carried out as described below. In the separating space 318 between the compartment wall 309 and the guide wall 328, particles 332 loaded with deposits are introduced into the sonication fluid 311 and sink downward under their own weight. As they pass the path downwards, they are sonicated by sound waves from the sound probe 302, and the deposits 334 are detached from the particles 332, that is to say they are liberated. They remain in this released state, since the spherical section 324 is also caused to vibrate by the sound probe 302 and therefore also transmits these vibrations in the region under the guide wall 328 to the sounding fluid 311. As soon as the particles 332 and the detached deposits 334 leave the annular region between the compartment wall 309 and the guide wall 328, the detached deposits 334, the size of which is generally smaller than the size of the particles 332, get into a flow (arrow P), which is generated by a liquid that is admitted through line 312. The detached and released deposits 311 are moved upward in the annular channel between the guide wall 328 and the wall of the container 310 by the flow P. transported and can be removed there (arrow Q). The heavier particles 332, which have been freed of the deposits 324, go down through their own weight against the upward flow P and can leave the container 310 and be removed through the line 312.

In the fourth embodiment of the invention according to FIG. 8, the compartment wall 409 encloses the resonator 403 as in the example according to FIG. 1. In the container 410 there is a treatment room 418 which is delimited by two liquid-permeable wall surfaces 428,446. The lower end of the inner wall 428 of the treatment room 418 is connected to a floor 438; the outer wall 446 is connected to the bottom of the container 410. The container 410 is connected to a line 412 at the bottom via a valve 440. The outer wall 446 is further connected at the bottom to a feed line 442 and at the top a drain line 444 for rinsing liquid.

Liberating and separating contaminated particles 432 and deposits 434 is described below. Contaminated particles 432 are introduced into the annular space of the treatment space 418 and sink downward in the sonication fluid 411 and are sonicated at the same time. The detached liberated deposits 434 are rinsed out by a liquid flow (arrows R) which is introduced between the compartment wall 409 and the inner wall 428 of the treatment room 418 and through the treatment room 436 and can be rinsed there by a further liquid flow (arrows S) above or below, if the flushing takes place in the opposite direction, can be removed from the container 410. The cleaned particles 432 leave the container 410 - 11 -

through line 412. Contaminated particles with a very low density, e.g. shredded dirty

Styrofoam or the like, are on from below and from above

Container 410 discharged.

The dwell time of the particles 432 to be cleaned can be controlled with the flow velocity in the line 412.

Batch operation can take place by closing the treatment room 436 - below and / or above.

In the fifth embodiment of the invention according to FIG. 9, the compartment wall 509 is formed by the inner wall of the treatment room 518. Otherwise, the design of the device (resonator 503, container 510) and the functioning of the cleaning of the particles 532 are identical to those in the fourth exemplary embodiment.

In the fifth embodiment of the invention according to FIGS. 10 and 11, the compartment wall 609 is designed as a tube and wraps around the resonator 603 in a helical manner. Both the helical compartment wall 609 and the resonator 603 are immersed in the transmission liquid 615, which is filled in a container 610. In the interior of the tubular compartment wall is the sonication liquid 611 with the parts 632 loaded with deposits 634.

In FIG. 10, the sonication liquid 611 with the deposits 634 detached during the passage is passed into a separation device, in the present example into a centrifuge 650. In the centrifuge 650, deposits 634 and sonication liquid 611 are separated from the particles 632. The particles 632 can be, for example, kieselguhr particles from beer filtration be, of which deposits 634 of yeast, protein and the like have been removed in the device. In the device according to FIG. 11, the particles 632 are separated from the detached impurities 634 in an upflow classification process at the end of the helical sound path. The cleaned, mostly large particles 632, for example foundry sand, sink in the container 610 and leave it at its lower end. A rinsing liquid is introduced from below, which transports the detached particles 634 upwards, where they can also leave the container 610.

The term transmission fluid used in the description is understood to mean a fluid which essentially contains no or only a small number of low-mass particles and consequently counteracts the propagation of the sound waves with little damping.

The sonication liquid can support the cleaning effect and the removal of the deposits, e.g. Lye.

The transmission fluid can be identical or different with the sonication fluid.

The sound probe can e.g. an ultrasonic probe RS-20 available from Telsonic AG CH-9552 Bronschhofen or a similar product.

Both the rigid and the bag-shaped compartment wall can only extend over part or the entire height of the sound container.

Claims

1. Method for sonication and transmission of

Vibrations on a sounding fluid containing particles for detaching impurities from particles introduced in the sounding fluid by means of a sound reinforcement device, with a sound generator, a sound transducer and an attached resonator excited by the sound transducer, characterized in that the sound waves generated by the resonator (3,103,203,303,403,503,603) initially transferred to a transmission liquid (15, 315, 215, 315, 415, 515, 615) that is in direct contact with the resonator (3, 103, 203, 303, 403, 503, 603) and forwarded through it and directly or indirectly to the sonication liquid (11, 211, 311, 411, 511, 611) and that in the sonication liquid (11, 211, 311, 411, 511, 611) introduced particles to be sonicated (32,132,232,332,432,532,632) is transferred, that deposits (34,134,234,334,434,534,634) on the particles (32,132,232,332,432,532,632) are detached and kept in paid form.

2. The method according to claim 1, characterized in that the vibrations generated by the sound transducer (6) and transmitted by the resonator (3,103,203,303,403,503,603) are transmitted to the transmission liquid (15,115,215,315,415,515,615) and in that the vibrations from the transmission liquid (15,115,215,315,415,515,615) via a compartment wall (9,109,309,409) or through this to the sound reinforcement (11,111,211,311,411,511,611) and the particles to be sonicated therein (32,132,232,332,432,532,632).

3. The method according to claim 2, characterized in that a liquid-permeable compartment wall (9,17,109,509,609) is used and particle-free or low-particle sonication liquid (11,111,511,611) is used as the transmission liquid (15,115,515,615).

4. The method according to claim 2, characterized in that the sonication takes place through a compartment wall which is completely or partially sealed (9,109,309,409,509,609).

5. The method according to claim 1, characterized in that the transmission fluid (215) or particle-free sound reinforcement form a protective flow (R) and prevent direct contact between the particles to be sonicated (232,432,532) and / or the sound reinforcement and the resonator (203,403,503).

6. The method according to any one of claims 1, 4 and 5, characterized in that the compartment wall (609) u closes the sonication liquid (111,611) at least in the area of the transmission liquid (115,615).

7. Device for generating and transmitting vibrations to a sonication liquid in a sonication container, with a sound probe, with at least one sound transducer and a resonator connected to the sound transducer and vibratable by the latter, characterized in that at least a part of the surface of the resonator (3,103,303,403,503,603), which is used to transmit the vibrations to the particles to be sonicated and introduced in the sonication fluid (11,111,211,311,411,511,611) (32, 32,232,332,432,532,632) is separated from the particles to be sonicated by a partition wall (9,109,309,409,509,609), a low-dampening liquid (315, 415, 215, 115, 415, 215 ] 5, 515, 615) is present.

8. The device according to claim 1, characterized in that the surface of the compartment wall (9) is structured or that on the compartment wall (9) elevations or rod-shaped vibration elements (21) are attached.

9. Device according to one of claims 7 or 8, characterized in that at least a portion of the compartment wall (9,109,309,409,509,609) is tubular or that the compartment wall (9,109,309,409,509,609) has perforations, is designed as a bag or as a grid, net or as a textile fabric.

10. The device according to one of claims 7 to 9, characterized in that the compartment wall (9,109,309,409,509,609) extends over part or the entire height of the sound container (10,110,210,310,410,510,610).

11. Device according to one of claims 7 to 10, characterized in that there is a protective flow (R) between the surface of the resonator (3,103,203,403,503) and the sonication liquid (15,115,215,415) with the introduced particles (32,232,432,532).

12. Device according to one of claims 7 to 11, characterized in that the compartment wall (9,409,509) surrounds the resonator (3,303,403,503) or that the compartment wall (109) is inserted within the tube-shaped resonator (103).

13. Device according to one of claims 7 to 10, characterized in that between the compartment wall (309) and the wall of the container (310), with the formation of two annular spaces, a Fuhrungεwand (328) is used, which is at a distance above the lower End of the compartment wall (309) ends, and that means (312) for introducing a liquid are arranged on the container (310).

14. The apparatus according to claim 13, characterized in that the lower end (324) of the compartment wall (309) has a thickening or is spherical and that there is a gap (S) between the lower end (330) of the guide wall (328) .

15. Device according to one of claims 7 to 12, characterized in that between the compartment wall (409) and the wall of the container (410) a liquid-permeable treatment room (418) is used, which can be flushed with a liquid (415).

16. The device according to claim 15, characterized in that the treatment room (418) is open at the top and bottom for online operation or is closable below and / or above for batch operation and is designed and intended to be cleaned and introduced from above or from below Record particles (432).

17. The device according to claim 16, characterized in that the area between the outer wall of the treatment room (418) and the wall of the container (410) is designed to be flushable.

18. Device according to one of claims 15 to 17, characterized in that the compartment wall simultaneously forms the inner wall of the treatment room (436).

19. The apparatus according to claim 7, characterized in that the compartment wall (609) is designed as a helical hollow body that at least partially wraps around the resonator (603) or that is immersed in the transmission liquid (615) and that is immersed in the transmission liquid (615).

20. The apparatus according to claim 19, characterized in that the lower end of the compartment wall (609) formed as a hollow body opens into a separation device (650).

21.Device for generating and transmitting vibrations to a particle-laden acoustic fluid, with a sound probe, with at least one sound transducer and a resonator connected to the sound transducer and vibratable by it, characterized in that means for introducing a transmission fluid to form a liquid jacket ( 216) are provided around the resonator (203).