DEVICE AND METHOD FOR DISPERSING GASES INTO LIQUIDS

Abstract

A device according to the invention for dispersing a gas into a liquid comprising a liquid volume and a nozzle which is immersed in the liquid volume below a liquid level. The nozzle has a conical annular gap at the tip of which a nozzle opening is provided, and a liquid feed line opening tangentially into the conical annular gap. A gas feed line for a gas to be dispersed into the liquid volume opens into the liquid feed line, into the annular gap or in the region of the nozzle opening. The nozzle causes a strong swirling movement in the liquid fed into the liquid volume, which allows good dispersion of the gas that has been introduced via the gas feed line.

Claims

1. A device for dispersing a gas into a liquid having a liquid volume, the device comprising: a nozzle for feeding a liquid into the liquid volume, which nozzle has a conical annular gap that is disposed between a conical internal face of a nozzle casing and a guide cone and on the tip of said annular gap at a nozzle opening opens out into the liquid volume below a liquid level; a liquid infeed which opens tangentially into the conical annular gap; and at least one gas infeed for a gas to be dispersed into the liquid volume, which gas infeed opens out into the liquid infeed and/or the annular gap and/or in the region of the nozzle opening.

2. The device as claimed in claim 1, wherein the at least one gas infeed is guided through the guide cone or the nozzle casing, and opens out into the annular gap at a gas exit opening.

3. The device as claimed in claim 1, wherein the at least one gas infeed is guided through the guide cone, and opens out into the nozzle opening at a gas exit opening disposed in the tip of the guide cone.

4. The device as claimed in claim 1, wherein the at least one gas infeed in the liquid volume opens out laterally to the nozzle opening and at an angle to a central axis of the conical annular gap.

5. The device as claimed in claim 1, wherein a ramp which starts at the mouth of the liquid infeed and ascends helically in the direction of the nozzle opening is provided in the annular gap.

6. The device as claimed in claim 1, wherein a vessel filled with liquid, or a liquid-conducting line, is provided as the liquid volume.

7. The device as claimed in claim 1, wherein a vessel filled with liquid is provided as the liquid volume, and additional means for generating a flow in the liquid are disposed in the vessel.

8. The device as claimed in claim 1, wherein the guide cone of the nozzle is axially adjustable in relation to the conical internal face of the nozzle casing.

9. The device as claimed in claim 1, wherein the nozzle opening is configured as a flat-jet nozzle.

10. The device as claimed in claim 1, wherein the nozzle is connected to a return line for circulating the liquid from the liquid volume.

11. A method for dispersing a gas into a liquid, in which method: a) a liquid is fed to a nozzle which has a conical annular gap, wherein the liquid is supplied into the annular gap by way of a liquid infeed that opens tangentially into the annular gap; b) the liquid in the annular gap is forced into a path constricted in the shape of a spiral, and at a nozzle opening disposed on the tip of the conical annular gap, below a liquid level of a liquid volume, is ejected in the form of a swirled liquid jet into the liquid volume; c) a gas to be dispersed is introduced into the liquid infeed and/or into the nozzle and/or into the swirled liquid jet ahead of the nozzle opening.

12. The method as claimed in claim 11, wherein the gas to be dispersed is at least partly introduced in a gas jet directed toward the swirled jet of the liquid exiting into the liquid volume at the nozzle opening.

13. The method as claimed in claim 11, wherein the volumetric flow ratio of liquid guided through the nozzle to the fed gas to be dispersed is between 5:1 and 1:2.

14. The method as claimed in claim 11, wherein the gas is ionized prior to being fed to the liquid.

15. The method as claimed in claim 11, wherein the gas is fed in a liquefied state into the swirled liquid jet ahead of the nozzle opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Exemplary embodiments of the invention are to be explained in more detail by means of the drawings, in which, in schematic views:

[0035] FIG. 1a shows a device according to the invention in a first embodiment, in a longitudinal sectional view;

[0036] FIG. 1b shows the device from FIG. 1a in a cross-sectional view along a section line B-B in FIG. 1a;

[0037] FIG. 2a shows a device according to the invention in a second embodiment, in a longitudinal sectional view;

[0038] FIG. 2b shows the device from FIG. 2a in a cross-sectional view along a section line B-B in FIG. 2a;

[0039] FIG. 2c shows the device from FIG. 2a in a cross-sectional view along a section line C-C in FIG. 2a; and

[0040] FIG. 3 shows a device according to the invention for treating a liquid in a vessel.

DETAILED DESCRIPTION

[0041] The device 1 shown in FIG. 1a and FIG. 1b comprises a nozzle 3 which is received within a liquid volume 2. The nozzle 3 comprises a nozzle casing 4 having a conical internal face into which a liquid infeed 5 opens tangentially. A likewise conically shaped guide cone 6 is disposed within the nozzle casing 4 in such a manner that a conical annular gap 7 lies open between the internal wall of the nozzle casing 4 and the external wall of the guide cone 6, preferably in such a manner that the cone tip 8 of the guide cone 6 is substantially co-aligned with a nozzle opening 9 of the nozzle 3. The nozzle opening 9 is preferably of such a size that the flow cross section thereof is substantially equal to or smaller than the flow cross section of the liquid infeed 5. The internal face of the conical nozzle casing 4 and the external face of the guide cone 6 here can have an identical opening angle; however, it is also conceivable that the opening angle of the external face of the guide cone 6 is more acute than the opening angle of the internal face of the nozzle casing 4, the spacing of the nozzle casing 4 and the guide cone 6 reducing in the direction toward the nozzle opening 9, as is shown in FIG. 1a.

[0042] Moreover, the nozzle opening 9 can have a circular cross section or a horizontally enlarged cross section as explained in more detail hereunder. The guide cone 6 can be fixedly assembled within the nozzle casing 4, or else be received so as to be axially movable in the latternot shown here.

[0043] A gas infeed 10, which is connected to a gas source not shown here, for example a pressurized gas cylinder or a pressurized tank, runs longitudinally along a central axis of the guide cone 6. The gas infeed 10 by way of a gas exit opening 11, which may also be configured as a nozzle, at the cone tip 8 of the guide cone 6 opens out into the nozzle opening 9.

[0044] During the operation of the device 1, a liquid to be treated is directed in the direction of the arrow 12 into the annular gap 7 by way of the liquid supply line 5, for example at a pressure of 2-3 bar. The liquid in the annular gap 7 is set in rapid rotation, the angular velocity of the latter movement increasing up to the nozzle opening 9 due to the radius of the annular gap 7 decreasing in the direction of flow. For the same reason, the linear speed component directed in the direction of the nozzle opening 9 also increases. The liquid leaves the nozzle 3 at the nozzle opening 9 and is introduced in the liquid volume 2 as an intensely swirled jet 13 at a high speed in the direction of the arrow 14. Due to the high rotating speed, a zone with a greatly reduced pressure is created along a central axis 15 of the jet 13.

[0045] A gas to be dispersed in the liquid volume 2 is directed inward in the direction of the arrow 16 at a high pressure of, for example, 10 bar to 20 bar, by way of the gas infeed 10. The gas exits the gas exit opening 11 at a high speed and from there makes its way into the interior of the swirled liquid jet 13. Conjointly with the latter, the gas is introduced deep into the liquid volume 2, and owing to the forces acting within the swirled jet 13, is gradually divided into fine bubbles with a diameter of a few micrometers, for example, and is finely distributed (dispersed) in the liquid volume 2. A cylindrical front portion 17, which is optionally disposed on the nozzle opening 9 ahead of the cone tip 8, leads to the liquid jet 13 being more heavily focused.

[0046] The device 20, shown in FIGS. 2a, 2b and 2c, likewise comprises a nozzle 22 which is received within a liquid volume 21. The nozzle 22 has a nozzle casing 23 having a conical internal face, a liquid infeed 24 opening tangentially into the latter. A likewise conically shaped guide cone 25 is disposed within the nozzle casing 23 in such a manner that a conical annular gap 26 lies open between the internal wall of the nozzle casing 23 and the external wall of the guide cone 25, specifically in such a manner that the cone tip 27 of the guide cone 25 is substantially co-aligned with a nozzle opening 28 of the nozzle 22. In this exemplary embodiment, the opening angles of the internal face of the nozzle casing 23 and the external face of the guide cone 25 are identical.

[0047] In the exemplary embodiment as per FIGS. 2a-2c the nozzle opening 28 has a horizontally enlarged cross section, for example the oval cross-section shown in FIG. 2c, in which the horizontal width a of the nozzle opening 28 is larger than the vertical height b.

[0048] The gas to be dispersed in the liquid volume 21 in the device 20 is directed inward by way of a gas infeed 29 whichas shown hereis disposed within the nozzle casing 23, or else outside the nozzle casing 23, and at a gas exit opening 30 exits laterally to the nozzle opening 28 but so as to be inclined in the direction toward a central axis 31 of the nozzle 22.

[0049] During the operation of the device 20, a liquid to be treated is directed in the direction of the arrow 32 into the annular gap 26 via the liquid infeed 24 at a pressure of 2 bar to 3 bar, for example. The liquid in the annular gap 26 is set in rapid rotation, the angular velocity of the latter movement increasing up to the nozzle opening 28 due to the radius of the annular gap 26 decreasing in the direction of flow. For the same reason, the linear speed component directed in the direction of the nozzle opening 28 also increases. The liquid leaves the nozzle 22 at the nozzle opening 28. Due to the horizontally enlarged nozzle opening 28, a planar jet pattern 33 is generated within the liquid volume 21. For example, two primary jets swirling in the same direction are formed in the liquid entering the liquid volume 21, a secondary jet in the opposite direction being formed therebetween, wherein a zone with a heavily reduced pressure is formed in each of the jets due to the high rotating speed.

[0050] A gas to be dispersed in the liquid volume 21 is directed inward in the direction of the arrow 34 by way of the gas infeed 29, at a high pressure of 10 bar to 20 bar, for example. The gas exits the gas exit opening 30 at a high speed, and makes its way from there into the interior of the swirled liquid jets in the jet pattern 33. In the process, the gas is introduced deep into the liquid volume 21, and owing to the forces acting within the swirled jets, is gradually divided into fine bubbles with a diameter of a few micrometers, for example, and is finely dispersed in the liquid volume 21.

[0051] In order to guarantee an ideally efficient rotational acceleration of the liquid introduced into the nozzle 20, a ramp 35 is provided in the annual gap 26. Owing to the ramp 35, the base area of the annular gap 26 does not form a flat circular ring, but forms a winding of a screw surface which ascends in the direction toward the nozzle opening 26 and which, at the ramp end 36 thereof, by a distance corresponding to the diameter of the liquid supply line 24, extends further in the direction of the nozzle opening 28 than at the entry point 37 of the liquid supply line 24 into the annular gap 26. In this way, the liquid, after passing the ramp 35, does not laterally impact the flow of the liquid directed inward by way of the liquid supply line 24, but is offset thereto, as a result of which turbulences which restrict the acceleration of the liquid are avoided.

[0052] Moreover, a nozzle 22 having a gas infeed 29 set at an acute angle does not mandatorily have to have a horizontally enlarged nozzle opening 28; of course, the nozzle opening 28 may also have a circular cross section, or the nozzle opening 9 of the nozzle 3 may have a horizontally enlarged cross section. Likewise, a ramp 35 can also be provided in an arrangement corresponding to that of the nozzle 1.

[0053] Shown in FIG. 3 is an exemplary embodiment in which a liquid volume is continuously circulated by means of a device according to the invention and is mixed with gas in the process.

[0054] The device 40 shown in FIG. 3 comprises a nozzle 41 according to the invention, this being, for example, a nozzle 3, 22 of the type described above. The nozzle 41 is received in a liquid volume 43 below a liquid level 42, said liquid volume 43 being present in a vessel 44. The vessel 44 is, for example, a largely closed vessel, a wastewater treatment tank for receiving wastewater, or a fish farm.

[0055] The device 40 has a liquid infeed 45 which is fluidically connected to a return line 46 immersed in the liquid volume 43. A conveying unit 47, for example a pump, is disposed in the return line 46. Liquid is continuously retrieved from the liquid volume 43 and supplied into the nozzle 41 by means of the conveying unit.

[0056] The gas to be dispersed into the liquid volume 43 is retrieved from a gas source 48, for example a pressurized vessel or a pressurized line, fed to the nozzle 41 by way of a gas infeed 29, and dispersed in the liquid in the way described above. The gas is, for example, oxygen or carbon dioxide. For example, gas and liquid are introduced by way of the nozzle 41 at a gas-to-liquid volumetric flow ratio such as 2:1. In order to improve mixing in particular in the case of large vessels, means not shown here, for example a recirculation pump, for generating an additional flow 50 can be provided in the vessel.

[0057] Owing to the special construction of the nozzle, the device 40 according to the invention is suitable for dispersing the gas even when the liquid supplied into the nozzle 41 by way of the return line 46 is heavily loaded with solid particles. Since the nozzle 41 contains neither voids such as mixing chambers, for example, nor static mixing elements, particles of this type do not accumulate within the nozzle 41 and are correspondingly unable to impede the functionality of the device 40. Rather, the conical configuration of the annular gap 7, 26, owing to the cross-sectional constriction, causes a high speed of the introduced liquid also in the axial direction, this facilitating the delivery and the distribution of the solids (or in more general terms: of substances with a higher density than the liquid per se) in the liquid volume.

LIST OF REFERENCE SIGNS

[0058] 1 Device 26 Annular gap [0059] 2 Liquid volume 27 Cone tip [0060] 3 Nozzle 28 Nozzle opening [0061] 4 Nozzle casing 29 Gas infeed [0062] 5 Liquid infeed 30 Gas exit opening [0063] 6 Guide cone 31 Axis [0064] 7 Annular gap 32 Arrow [0065] 8 Cone tip 33 Jet pattern [0066] 9 Nozzle opening 34 Arrow [0067] 10 Gas infeed 35 Ramp [0068] 11 Gas exit opening 36 Ramp end [0069] 12 Arrow 37 Entry point [0070] 13 Jet 38 - [0071] 14 Arrow 39 - [0072] 15 Axis 40 Device [0073] 16 Arrow 41 Nozzle [0074] 17 Cylindrical front portion 42 Liquid level [0075] 18 - 43 Liquid volume [0076] 19 - 44 Vessel [0077] 20 Device 45 Liquid infeed [0078] 21 Liquid volume 46 Return line [0079] 22 Nozzle 47 Conveying unit [0080] 23 Nozzle casing 48 Gas source [0081] 24 Liquid infeed 49 Gas infeed [0082] 25 Guide cone 50 Flow