FR2906734A1 - Sonoreactor for treating fluid e.g. liquid in enclosure, comprises an enclosure having a portion of longitudinal wall that extends around a rectilinear axis, a high frequency generator, and an ultrasonic resonator piloted by the generator - Google Patents

Abstract

The sonoreactor for treating a fluid (14) e.g. liquid in an enclosure, comprises an enclosure (12) having a portion of longitudinal wall (16) that extends around a rectilinear axis (X-X') and that has an inner surface, a high frequency generator (20), and an ultrasonic resonator (22) piloted by the generator. The resonator is arranged for generating an ultrasonic field of wavelength (lambda ) in a fluid situated in the enclosure, and comprises a longitudinal portion that extends in the enclosure around a rectilinear axis (X-X') and that has an outer surface immersed in the fluid. The sonoreactor for treating a fluid (14) e.g. liquid in an enclosure, comprises an enclosure (12) having a portion of longitudinal wall (16) that extends around a rectilinear axis (X-X') and that has an inner surface, a high frequency generator (20), and an ultrasonic resonator (22) piloted by the generator. The resonator is arranged for generating an ultrasonic field of wavelength (lambda ) in a fluid situated in the enclosure, and comprises a longitudinal portion that extends in the enclosure around a rectilinear axis (X-X') and that has an outer surface immersed in the fluid. The inner surface and outer surface are separated each other by a distance (d), which is equal to K(lambda /2), where K is a natural number, and cylindrical around the rectilinear axis. A portion of the inner surface has a non-linear profile having alternative modulations. The profile is asymmetrical to the rectilinear axis. The inner surface has a roughness >= 2. The enclosure further comprises an entrance- and an end opening, and a unit to force a flow of the fluid between the openings. One of the openings is centered in the rectilinear axis, and formed in a tapered transverse wall of the enclosure. A spiral element is disposed to an inner of the enclosure.

Description

The invention relates to a sonoreactor and the use of such a

  a sonjet comprising: an enclosure having at least one longitudinal wall portion which extends around an axis and which has an inner surface, said enclosure being able to contain a fluid, a high frequency generator, an ultrasonic resonator controlled by said generator for generating an ultrasonic field of wavelength 2 in a fluid located in said chamber, said resonator comprising at least one longitudinal portion which extends in the chamber about said axis and which has an outer surface immersed in the fluid located in said enclosure.

  Such sonoreactors allow ultrasonic treatment of a fluid located in the chamber. Fluid includes liquids, liquid / solid mixtures such as suspensions, dispersions, slurries, colloids, biological tissues, drug or cosmetic preparations, etc. Ultrasound is a form of vibratory energy that when propagated through a fluid interacts with it. These ultrasonic interactions with a fluid have been known and exploited for many years in devices that clean or separate materials, which accelerate or modify chemical reactions. Such sonoreactors are known, in which the ultrasonic resonator is disposed partly inside the enclosure. However, in known sonoreactors, the wall forming the enclosure has a substantially smooth inner surface, so that the ultrasonic wave which arrives at the same point of the wall is all the time reflected in the same way. Since the ultrasonic wave propagates in a wave-like manner, it will be understood that some places in the fluid are therefore strongly subject to the ultrasound field, while others are not (or little) subject to said field. On the other hand, the ultrasonic vibration is rapidly attenuated by diffusion and / or energy absorption, passing through long paths in the fluid, so that the speakers used in such sonoreactors are generally small. As a result, the amount of treated fluid remains low per unit of time and the fluid to be treated may be subjected to improper heating. The object of the invention is to improve the performance of sonoreactors, in particular by allowing better transmission of the ultrasonic energy to the fluid located in the chamber. This object is achieved by the fact that the inner surface of the longitudinal wall portion of the enclosure and the outer surface of the longitudinal portion of the ultrasonic resonator are spaced from each other by a distance d substantially equal to k-, where k is a natural number. With such a geometry of the sonoreactor, because the propagation of the ultrasonic wave is wave-shaped, it follows that the amplitude of the wave which is reflected against the inner wall of the enclosure is substantially the same. same as that of the emitted wave giving birth to it. Preferably, at least a portion of said inner surface has a non-linear profile. By nonlinear it is understood that the surface has asperities in shape. Such a non-linear profile makes it possible to reflect the ultrasonic waves in a multidirectional manner, thereby generating a more homogeneous ultrasound field within the fluid located in the chamber. In various embodiments of the reciprocator according to the invention, one or more of the following arrangements may also be used. 5 - the non-linear profile has an alternation of inflections, - the profile of the portion is asymmetrical with respect to said axis, - the inner surface has a roughness Ra 10 greater than or equal to 2, - said enclosure further comprises at least an inlet opening and at least one outlet opening and further comprises means for forcing a flow of fluid between said inlet and outlet openings, - an opening selected from the inlet and outlet openings is centered on the axis XX 'and is formed in a transverse wall of the enclosure and said transverse wall having said opening 20 is frustoconical, - means for forcing a flow comprise a helical element disposed inside said enclosure, the axis is a rectilinear axis and the inner surfaces of the longitudinal wall portion of the enclosure and the outer surface of the longitudinal portion of the resonator are cylindrical a around said rectilinear axis, the ultrasonic resonator is entirely located in said enclosure, the sonoreactor comprises means for controlling various characteristics (temperature of the fluid in the enclosure, pressure, etc.), as well as means for regulating the temperature of the fluid, the fluid to be treated may be contained in the chamber statically or on the contrary dynamic; in the latter case, the fluid can flow continuously or discontinuously. The invention will be better understood and its advantages will appear better on reading the detailed description which follows, of embodiments of the invention shown by way of non-limiting examples. The description refers to the accompanying drawings in which: - Figure 1 shows a longitudinal sectional view of a sonoreactor according to the invention - Figure 2 shows a sectional view along the line II-II of the sonoreactor of Figure 1 - Figure 3 shows a partial section of the enclosure of the sonoreactor according to a variant, and - Figure 4 shows a partial section of the speaker sonoreactor according to another variant. Figure 1 shows a longitudinal sectional view of a sonoreactor 10 comprising an enclosure 12 containing a fluid 14 to be treated with ultrasound. The chamber 12 has a longitudinal wall portion 16, in this case a cylindrical wall 16 of axis X-X '. The cylindrical wall 16 is preferably tubular, but the invention is not limited to this geometric form. The cylindrical wall 16 is preferably closed at each of its ends 16A, respectively 16B, by a first transverse wall 18A, respectively 18B.

  In order to generate an ultrasonic field in the fluid 14 contained in the chamber 12, the sonoreactor 10 further comprises a high frequency generator 20 of the known type, connected to an ultrasonic resonator 22. The ultrasonic resonator 22 comprises at least one longitudinal portion 24 which extends inside the enclosure 12, in this case a bar 24 preferentially disposed concentrically with the cylindrical wall of axis X-X '. This bar 24 is preferably solid and has an outer surface 26 which is immersed in the fluid 14. In this case, as illustrated in FIG. 1, the ultrasonic resonator 22 is completely integrated in the enclosure 12, so that the bar 24 can be fully immersed in the fluid 14. It can be provided that the ultrasonic resonator 22 passes through the wall of the chamber 12, but the above-mentioned configuration, in which it is entirely located inside the chamber, is preferred. enclosure 12, in order to avoid as much as possible the absorption of the ultrasonic energy by the wall of the enclosure 12.

The generator 20 is disposed outside the enclosure 12 and is connected to the ultrasonic resonator 22 by means of appropriate connection means 28. The ultrasonic resonator 22 further comprises piezoelectric elements 30 (or possibly magnetostrictive elements) of known type, connected to the generator 20. The ultrasonic resonator 22 is fixed by one of its two ends to one of the walls of the enclosure 12. In this case, the end 22A is fixed to the transverse wall 18A, so that the bar 24 is centered on the X-X 'axis. The other end 22B of the ultrasonic resonator 22 is free and preferably has a conical end portion 22B whose tip 22C is centered on the axis X-X '.

In order to allow circulation in the chamber 12 of the fluid 14 to be treated, an inlet opening 32 and an outlet opening 34 may be provided in at least one of the walls of the enclosure 12. The inlet opening 32 is preferably located on the cylindrical wall 16, for example in the upper part, while the outlet opening 34 is preferably formed in one of the transverse walls of the enclosure 12. It will be understood that the opening of FIG. Input 32 and output 34 can be inverted, the input then serving as an output and vice versa. In addition, as shown in Figure 1, the outlet opening 34 is preferably centered on the X-X 'axis being formed on the transverse wall 18B which is preferably frustoconical.

Thus, it is understood that the transverse wall 18B extends obliquely between the cylindrical wall 16 and the outlet opening 34. It is thus possible to use the sonoreactor 10 by treating a given volume of fluid 14, or In a static manner (the treated volume then corresponds at most to the internal volume of the chamber), or dynamically by circulating the fluid 14 continuously or discontinuously inside the chamber 12, between the opening of the chamber; In the latter case, it is understood that the volume of fluid treated may be greater per unit time, than in the case of a static treatment. According to the invention, the distance d between the inner surface 36 of the cylindrical wall 16 of the outer surface 26 of the bar 24 is substantially equal to k ~, where 1 represents the wavelength of the ultrasonic wave generated by the resonator 22 within the fluid 14, and k is a coefficient chosen from among the natural whole numbers [1, 2, 3, ..., n]. With reference to FIG. 2, the longitudinal wall 16, concentric with the bar 24, is preferably a cylinder of revolution centered on the axis XX 'which is rectilinear, so that the distance d which separates the outer surface 26 from the 2906734 7 bar 24 of the inner surface 36 of the longitudinal wall 16 is substantially constant, seen in cross section (Figure 2) and / or in longitudinal section along the axis XX '(Figure 1).

Thus, considering the diameter D26 of the outer surface 26 of the bar 24 and the diameter D36 of the inner surface 36 of the cylindrical wall 16, the distance d corresponds substantially to: 2 (D36-D26).

By way of example, for a sonoreactor 10 operating at a frequency of 40 kHz, the wavelength? is substantially of the order of 37.5 mm for a fluid 14 comprising water, so that the distance d must be an integer multiple of 18.75 mm (corresponding to X / 2). Thus, for example, a bar 24 having an outer surface 26 of diameter D26 substantially equal to 30 mm and an enclosure 12 having a cylindrical wall 16 having an inside surface having a diameter D16 substantially equal to 67.5 mm will be chosen for k = 1, or substantially equal to 105 mm for k = 2, etc. In the same way, it can be provided that the inner surface of the frustoconical transverse wall 18B is also at the same distance d from the conical end portion 22B (FIG. 1). In order to obtain a homogeneous ultrasound field within the fluid 14, the inner surface of the walls of the enclosure 12 and in particular of the inner surface 36 of the longitudinal wall 16 (or at least a portion 36 'of said inner surface 36) has a profile P which is nonlinear. In this case, it is preferable that the surface is not smooth, so that the wave arriving on the inner wall is reflected multidirectionally.

FIGS. 3 and 4, in which only the longitudinal wall 16 is schematically illustrated in part with an exaggerated enlargement of the profile, show two other variants of embodiment, in which the profile P of the inner surface of the enclosure and in particular that of the inner surface 36 of the longitudinal wall 16 follows an alternation of inflections, in this case an alternation of projections S and recesses C.

In the present case, as illustrated in FIG. 3, the profile P has a sinusoidal shape. Those skilled in the art will choose a sinusoidal shape appropriate according to the ultrasonic frequency and the fluid to be treated. By way of example, it will be possible to choose a step (difference between two consecutive S protrusions) of the order of 4 mm and an amplitude (difference between the vertex of a projection S and the bottom of a consecutive recess C). of the order of 1 mm. With reference to FIG. 4, the profile P follows an alternation of inflections I, in this case a sawtooth form, preferably of the same values as mentioned above. Whatever the variant, the profile P is preferably asymmetrical, that is to say seen in longitudinal and / or transverse section, the top 25 of a projection S1 is not opposite another projection S2 (Figure 3). With regard to the distance d between the outer surface 26 of the bar of the inner surface 36, it will be understood that the diameter D36 considered for the distance d substantially corresponds to the nominal diameter of the profile P of the inner surface 36. ie the average diameter of the inner surface (diameter between generators G1 and G2 located at the average distance between the peaks 35 of the projections and the bottoms of the hollows, as shown in Figures 3 and 4).

With reference to FIG. 2, according to another embodiment which can be taken alone or in combination with the embodiments of FIGS. 3 and 4, the inner surface of the enclosure 12 and in particular the inner surface 36 the cylindrical wall 16 (or at least a portion 36 'of said inner surface 36) preferably has a rough surface condition; in this case, the surface has a roughness such that the arithmetical average deviation Ra of the profile P is greater than or equal to 2 μm, preferably between 2 μm and 100 μm, in particular of the order 12 μm. In order to improve the ultrasonic treatment of the fluid 14, means may be provided for forcing the flow of the fluid 14 into the chamber 15. In this case, the means for forcing the flow comprise a helical element 38 disposed inside the enclosure 12, in particular as illustrated in FIG. 1, between the inner surface 36 of the cylindrical wall 16 and the outside 20 of the bar 22. It is understood that this element The spiral 38 guides the fluid 14 by circulating it spirally around the bar 22. Thus, the fluid 14 travels a longer path in the chamber 12, so that it is subjected longer to the ultrasonic field than in the absence of such means to force the flow. In order to control characteristics of the treated fluid, such as, for example, its temperature, pressure, etc., the reciprocator 10 may further include control means of the known type. In this case, the sonjet 10 may comprise a temperature probe 40 disposed in the chamber 12. Moreover, heating and / or cooling means 42 may be provided to apply a given temperature to the fluid 14. In this case, As illustrated in FIG. 1, the heating and / or cooling means 42 comprise, for example, a heat transfer fluid 44 which circulates preferentially around the chamber 12 in a chamber 46 provided for this purpose.

Regulating means 48 may be connected to the control means and the heating and / or cooling means 42 in order to regulate the temperature. Similar means can be provided for regulating the pressure of the fluid 14 in the chamber 12.

The use of a sonoreactor 10 as described allows ultrasonic treatment of fluid-like fluid, liquid / solid mixtures such as suspensions, dispersions, slurries, colloids, biological tissues, The treatment, for example, includes cleaning, mixing or separating material (s), depolluting, accelerating or modifying chemical reactions, and the like.

Depending on the use of the sonoreactor, a person skilled in the art will choose materials that are particularly suitable for the enclosure and for the means for forcing the flow. These materials are for example chosen from stainless steels, glasses, plastics, etc.

Claims (11)

  1. Sonoréacteur comprising: - an enclosure (12) having at least one longitudinal wall portion (16) extending about an axis (X-X ') and having an inner surface (36), said enclosure ( 12) being able to contain a fluid (14), - a high frequency generator (20), - an ultrasonic resonator (22) controlled by said generator (20) to generate an ultrasonic wave field? in a fluid (14) located in said enclosure (12), said resonator (22) comprising at least one longitudinal portion (24) extending in the enclosure (12) about said axis (X-X ') and which has an outer surface (26) immersed in the fluid (14) located in said enclosure (12), characterized in that said inner surface (36) of the longitudinal wall portion (16) of said enclosure (12) and said surface outer portion (26) of the longitudinal portion (24) of the resonator (22) are spaced from each other by a distance d substantially equal to k2, where k is a natural number.   2. Sonoreactor according to claim, wherein at least a portion (36 ') of said inner surface (36) has a profile (P) nonlinear.   3. Sonoreactor according to claim 1, wherein the nonlinear profile (P) has an alternation of inflections (I).   4. Sonoreactor according to claim 2 or 3, wherein the profile (P) of said portion (36 ') is asymmetrical with respect to said axis (X-X'). 2906734 12   5. Sonoreactor according to any one of the preceding claims, wherein the inner surface (36) has a roughness Ra greater than or equal to 2. 5   6. Sonoreactor according to any one of the preceding claims, wherein said enclosure (12) further comprises at least one inlet opening (32) and at least one outlet opening (34) and further comprises means for forcing a flow (38) of a fluid (14) between said inlet and outlet openings (32, 34).   7. Sonoréactor according to the preceding claim, wherein an opening (34) selected from the inlet and outlet openings (32, 34) is centered on the axis XX 'and is formed in a transverse wall (18B) of the enclosure (12) and said transverse wall (18B) having said opening (34) is frustoconical.   8. Sonoréactor according to the preceding claim, 20 wherein said means for forcing a flow (38) comprise a helical element (38) disposed within said enclosure (12).   9. Sonoreactor according to any one of the preceding claims, wherein the axis (X-X ') 25 is a straight axis (X-X') and said inner surface (36) of the longitudinal wall portion (16) the enclosure (12) and said outer surface (26) of the longitudinal portion (24) of the resonator (22) are cylindrical about said straight axis (X-X ').   10. Sonoreactor according to any one of the preceding claims, wherein the ultrasonic resonator (22) is entirely located in said enclosure (12). 2906734 13   11. Use of a sonjet (10) according to any one of the preceding claims for treating a fluid (14) in said enclosure (12).