EP1674151B1 - Apparatus for dispersion of a solid, liquid or gaseous substance in a liquid - Google Patents

Abstract

Device for dispersing a material in a liquid comprises a dispersing chamber (10) containing a drive unit (12) by which the liquid is displaced in the chamber to form cavities with changing volumes to suction material through a material inlet and to eject the material with the liquid through the outlet.

Description

The present invention relates to an apparatus for dispersing a substance in a liquid.

Such devices serve to form a dispersion by finely distributing the substance in a liquid. The substance may be in solid, liquid or gaseous phase or else as a mixture of different phases. The problem with the mixing process is often the wetting and the homogeneous distribution of the substance. If this is powdery, there is also the danger that unwanted dust from unwetted powder forms in the environment.

It is known to supply liquid and substance to a dispersion chamber and to work intensively by means of dispersing tools in order to achieve a fine distribution of the substance (see, for example, the patents EP-B1-436 462 and EP-B1-648 537 the same applicant or the patent EP-B1-587,714 ). However, it has been found that the wetting of the substance with liquid is problematic and can lead to undesirable inhomogeneities in the distribution. For example, if a powdered substance is supplied, it may in the mixing zone, ie where the substance comes into contact with the liquid come to the formation of lumps, which clog the material supply line or complicate a homogeneous distribution of the substance in the liquid. The known dispersing devices also have the disadvantage that the suction power depends on the liquid flow rate and the pressure at the outlet, so that it may be too low to be able to suck in and wet the substance to be dispersed to a sufficient extent.

From the patent US-A-3,119,339 a device for generating a dispersion of gas and liquid is known. The device comprises an eccentrically arranged gear with internal teeth, which engage in a pinion, and a crescent-shaped insert. This arrangement has, inter alia, the disadvantage that it is unsuitable for dispersing powdery substances. Since these are almost incompressible, the meshing of the internal teeth in the pinion would generate such large forces that the device would be damaged, for example, in the walls of the teeth or the pinion or possibly in the camps. Another disadvantage is that the throughput and thus the volume of dispersion that can be generated per unit time are relatively low.

From the patents US-A-3,936,246 and US B1-6,616,325 Devices are known which have radially displaceable wings for generating a variable working volume. Such arrangements have the disadvantage that there are narrow spaces which are susceptible to accumulation of the substance to be dispersed. In particular, if this is powdery, such accumulation can lead to jamming of the wings in the guides and finally to a failure of the device.

Starting from this prior art, an object of the present invention is to provide a device which allows in an improved way to suck in substance and to distribute as homogeneously as possible in a liquid.

A device which achieves this object is specified in claim 1. The other claims indicate preferred embodiments.

• Fig. 1 eine teilweise geschnittene Seitenansicht der erfindungsgemässen Vorrichtung;
• Fig. 2 die Vorrichtung gemäss Fig. 1 in der Schnittebene II-II;
• Fig. 3 die Vorrichtung gemäss Fig. 1 in der Schnittebene III-III;
• Fig. 4 ein hydraulisches Schema der erfindungsgemässen Vorrichtung;
• Fig. 5 eine weitere Variante eines hydraulisches Schema der erfindungsgemässen Vorrichtung;
• Fig. 6 eine Seitenansicht einer weiteren Ausführungsform des Antreibemittels für die erfindungsgemässe Vorrichtung;
• Fig. 7 eine perspektivische Ansicht des Antreibemittels gemäss Fig. 5; und
• Fig. 8 eine weitere Variante der Öffnungen 30', 35' und 40' der Vorrichtung gemäss Fig. 1 in der Schnittebene II-II.

The invention will be explained below with reference to a preferred embodiment with reference to figures. Show it

• Fig. 1 a partially sectioned side view of the inventive device;
• Fig. 2 the device according to Fig. 1 in section plane II-II;
• Fig. 3 the device according to Fig. 1 in the section plane III-III;
• Fig. 4 a hydraulic diagram of the inventive device;
• Fig. 5 a further variant of a hydraulic scheme of the inventive device;
• Fig. 6 a side view of another embodiment of the driving means for the inventive device;
• Fig. 7 a perspective view of the driving means according to Fig. 5 ; and
• Fig. 8 a further variant of the openings 30 ', 35' and 40 'of the device according to Fig. 1 in the section plane II-II.

Like from the FIGS. 1 and 2 As can be seen, the dispersing device comprises a dispersing chamber 10, which is preferably bounded laterally by a cylindrical wall 11. The dispersing chamber 10 contains a driving means 12, by means of which liquid is set in motion. The driving means is preferably designed as an impeller 12. This comprises a hub 13 which is rotatable about the axis of rotation 16 and on which a plurality of wings 14 are mounted. The impeller 12 is arranged eccentrically in the dispersing chamber 10, so that the axis of rotation 16 is adjacent to the center 18 of the dispersing chamber 10. By this arrangement, during the rotation of the impeller 12, the distance between the base 15 of a blade 14 and the wall 11 of the dispersing chamber 10 changes between a minimum and a maximum value repeatedly. The axis passing through points 16 and 18 extends substantially in the neutral region where neither the suction generated in the dispersing chamber 10 nor the pumping action predominates.

The impeller 12 is fixed to a shaft 19, which is by means of drive (not shown) in rotation displaceable. In the in Fig. 1 Shown embodiment, the shaft 19 is arranged vertically. It is also possible to align the disperser in a different position, for example, so that the shaft 19 is arranged horizontally.

The dispersing chamber 10 is provided at the top with a cover 29, which contains a substance inlet 30 for introducing material into the dispersing chamber 10 and an outlet 35 for discharging the product from the dispersing chamber 10.

Inlet inlet 30 and outlet 35 are each connected to a supply line 31 and 36, respectively. If, as mentioned above, the shaft 19 is aligned horizontally, it is advantageous to arrange the material inlet 30 at a higher level than the outlet 35.

How out Fig. 2 As can be seen, the shape of the material inlet 30 and the outlet 35 is substantially sickle-shaped, so that the distance between the edges 32 and 33 of the fabric inlet 30 in the direction of rotation 17 increases and the distance between the edges 37 and 38 of the outlet 35 decreases in the direction of rotation 17. The inner edge 32 of the material inlet 30 and the inner edge 37 of the outlet 35 are approximately on a circle whose center lies on the axis of rotation 16 of the impeller 12. The outer edge 38 of the outlet 35 lies on a circle 39 which is substantially concentric with the wall 11 of the dispersion chamber 10. The outer edge 33 of the material inlet 30 is also substantially circular and arranged so that it lies within the circle 39. This arrangement counteracts the risk that, during operation, liquid from the dispersion chamber 10 can penetrate into the substance inlet 30 and the supplied substance is able to agglomerate.

If the shape of the feed line 31 to the substance inlet 30 is cylindrical, then the transition of the feed line 31 into the sickle shape of the material inlet 30 can be optimized so that even with high turbulence no liquid can spray from the dispersing chamber 10 into the material inlet 30. The transition to this is not abrupt in cross section, but for example, ramp-shaped, so seen in the direction of flow, the central part of the material inlet is higher than its two ends.

As Fig. 1 further shows, the dispersing chamber 10 below a disc 41 having a liquid inlet 40 for introducing liquid into the dispersing chamber 10. According to Fig. 2 For example, the liquid inlet 40 is arranged substantially between the material inlet 30 and the outlet 35, wherein the material inlet 30 is arranged in front of the liquid inlet 40 and in front of the outlet 35, viewed in the direction of rotation 17. The liquid inlet 40 has in the example according to Fig. 2 a substantially circular shape. In Fig. 1 For the sake of clarity, the position of the liquid inlet 40 is opposite to that in FIG Fig. 2 shown rotated position 90 degrees.

Preferably, the disc 41 is rotatably arranged so that the position of the liquid inlet 40 with respect to the neutral axis, which passes through the points 16 and 18, is variable. The dispersing device further comprises pumping means 61 for conveying liquid through the liquid inlet 40 into the dispersing chamber 10.

The dispersing device shown so far works as follows:

The impeller 12 is in the in Fig. 2 indicated direction 17 in rotation and pumped liquid by means of the pumping means 61 through the liquid inlet 40 into the dispersing chamber 10. By the rotating impeller 12, the liquid is also set in rotation and driven outwards due to the centrifugal force, so that it stands out from the hub 13 and a circumferential liquid ring 47 is formed, which is substantially concentric with the wall 11 of the dispersing chamber 10. In Fig. 2 is the transition between the ring 47 with circulating liquid and the liquid-reduced interior indicated by a dashed line 39. The position of this transition 39, and thus the thickness of the liquid ring 47, is essentially given by the position of the outer edge 38 of the outlet 35, because, as explained below, due to the pumping action, liquid located in the interior is conveyed through the outlet 35 ,

Between the base 15 of adjacent blades 14 and the liquid ring 47 is formed in each case a cavity 50-57, the volume of which is repeatedly increased and decreased by the rotation of the impeller 12, whereby a pumping action is generated. For example, from the in Fig. 2 Starting with the reference numeral 50 provided cavity, so increases their volume first, when it moves to the position of the cavity 51 out. By this increase in volume, a negative pressure is generated, which causes substance to be sucked through the substance inlet 30 into the dispersing chamber 10 and finally wetted with the liquid and mixed. The generated suction effect ensures that the substance does not already come into contact with liquid in the material inlet 30 and that the substance inlet 30 is clogged due to the formation of lumps.

The cavity 50 then passes through the area of in Fig. 2 denoted by the reference numerals 52 and 53 cavities, where their volume hardly changes, so that neither a suction nor pumping action is generated. In this neutral zone, the liquid inlet 40 is arranged. Thereafter, the cavity 50 moves in the direction of the position of the cavity 54, so that its volume decreases again and the product consisting of liquid and substance contained therein is expelled through the outlet 35. Thereafter, the cavity 50 passes through in the region of Cavities 55 and 56 again a neutral zone between the pressure and suction side.

The dispersion chamber 10 is designed so that the flow conditions are usually turbulent and a fine distribution of the substance in the liquid is favored.

By turning the disc 41, the mixing ratio of substance and liquid can be adjusted. In this case, the position of the liquid inlet 40 is displaced either more in the direction of the pressure side or more in the direction of the suction side, so that the amount of liquid which flows into the dispersing chamber 10 per unit time is regulated accordingly.

Due to the rotation of the driving means 12, intensive wetting of the substance in the dispersing chamber 10 takes place. As a result, the risk of lump formation is virtually eliminated, especially in the case of powdery substances. This is also effectively avoided by allowing the dispersing chamber 10 to be designed to be free of narrow gaps or other narrow spaces. Furthermore, during operation, a high vacuum is generated with a simultaneous high suction power and this is essentially independent of the fluid flow rate and, to a certain extent, also independent of the pressure at the outlet 35. As a result, dust-free incorporation into the liquid is ensured, in particular in the case of pulverulent substances. It has been found that the producible suction power is sufficient to handle even heavy powders, e.g. metal-containing powder to be able to suck.

The suction and pumping action of the dispersing device described here comes about in a similar way as for water ring pumps. In contrast to these pumps, however, the dispersing device is used here for optimum suction, wetting and dispersion of substance with or in the liquid. For this purpose, the dispersing device has a liquid inlet 40, so that the liquid in the ring is continuously exchanged during operation. Water ring pumps, on the other hand, contain water as the working fluid, which permanently remains in the working chamber.

In a first continuation of the dispersing device, the outlet 35 is fluidically connected to the liquid inlet 40. This allows the liquid to be passed through the dispersing chamber 10 several times. By this recirculation it is e.g. possible to concentrate the liquid successively with substance and / or to achieve a particularly homogeneous distribution of the substance in the liquid. In the latter case, advantageously, the material inlet 30 is e.g. closed by a valve and the dispersion passed through the dispersion chamber 10 several times.

In a second continuation of the dispersing device, which is also shown in FIG Fig. 1 is shown, a second dispersing chamber 60 is provided. This is fluidically connected via the liquid inlet 40 with the first dispersing chamber 10 and is located according to Fig. 1 below this. In the second dispersing chamber 60 at least one dispersing tool 61 is arranged, which serves as a pumping means and as a processing means to distribute the substance in the liquid very finely.

The dispersing tool 61 comprises rotor 62 and stator 63, wherein the rotor 62 is advantageously mounted on the same shaft 19 as the impeller 12. This allows the same drive to be used to set the impeller 12 and the dispersing tool 61 in motion.

Fig. 3 FIG. 16 shows an example of a dispersing tool 61 having two sprockets 62a and 62b forming the rotor 62 and two sprockets 63a and 63b constituting the stator 63. The sprockets 62a, 62b, 63a, 63b have slots 64 through which liquid and material contained therein can pass. Number and configuration of the sprockets 62a, 62b, 63a, 63b are selected according to the application. The dispersing tool 61 is provided in the inner region with a passage 69 which is fluidically connected to a supply chamber 70. This supply chamber 70 is located according to Fig. 1 below the dispersing tool 61 and includes an inlet 71. If the dispersion is to be recirculated, then the outlet 35 of the first dispersing chamber 10 is connected to the inlet 71.

When the dispersing device is put into operation, liquid is first sucked in from the supply chamber 70 by means of the dispersing tool 61 and pumped via the liquid inlet 40 into the first dispersing chamber 10, where, as already explained above, a liquid ring is formed. Cloth is drawn in through the fabric inlet 30 and dispersed in the liquid. The resulting dispersion is passed via the outlet 35 and the inlet 71 back into the feed chamber 70. The liquid and the substance contained therein are processed accordingly as they pass through the slots 64 of the rotor 62 and stator 63, resulting in a more refined and homogenized distribution of the substance. The liquid circulates several times between the first and second dispersing chambers 10 and 60 until the desired substance concentration and / or until a sufficiently homogeneous dispersion is achieved.

The provision of two dispersion chambers 10 and 60 has the advantage that the wetting of the substance with liquid and the machining with the dispersing tool 61 takes place in separate chambers and thus does not influence the two processes. This makes it possible to produce particularly homogeneous dispersions without problems with lump formation and / or with undesirable dust formation in the case of pulverulent substances.

Fig. 4 shows a third continuation of the dispersing device in a schematic form. Rectangle 80 is a schematic representation of the dispersing unit containing the first dispersing chamber 10 and the driving means 12 and, if provided, the second dispersing chamber 60 and the dispersing tool 61. Accordingly, reference numeral 81 designates the liquid inlet 40 in the absence of the second dispersing chamber 60 or the inlet 71, if present. The supply container 83 for receiving the substance to be dispersed is connected by a line 84 to the substance inlet 30. In the recirculation line 85, which connects the outlet 35 of the dispersion unit 80 with the inlet 81, a container 86 is arranged, which serves for the separation of gas and / or non-dispersed material. Optionally, a return line 87, as shown in the Fig. 4 is shown in dashed lines, be provided, which connects the separation vessel 86 with the supply container 83 to return the separated gas or the deposited material. Supply line 88, which is connected to the inlet 81, serves to supply the liquid. Discharge line 89, which opens into the recirculation line 85, serves to remove the dispersion made of liquid and fabric. The lines 84, 88 and 89 are provided in known manner with valves 90, 91 and 92, respectively, in order to open and block the respective passage.

If a dispersing tool 61 is provided, measures must be taken to minimize the amount of air in the liquid to be processed. Too much air may cause no liquid to pass through the slots 64 of the sprockets, thus interrupting operation. Contains now the liquid leaving the outlet 35, in addition to the substance and ambient air, it can be deposited in the separation vessel 86 and a safe operation of the dispersing 61 are ensured.

It is also possible to form the dispersing device as a closed system, so that gas exchange with the environment is prevented. The feed tank 83 and the separation tank 86 are formed closed in this case.

The use of a closed system is advantageous, for example, if the substance to be dispersed is a very fine powder and unwanted powder deposits in the environment are to be avoided. If the powder is difficult to disperse and / or very fine, it may be that undispersed powder is still present in the air, which is in the separation tank 86. This can be returned via the return line 87 to the feed container.

The use of a closed system is also advantageous when there is a risk of dust explosions when dispersing powdered material. In this case, the air in the dispersing device, in particular in the feed tank 83 and in the separating tank 86, is replaced by an inert gas, for example nitrogen. During operation, this is deposited in the separation vessel 86 and returned via the return line 87 into the supply container 83.

Fig. 5 shows a variant of the dispersing device for a batch operation, wherein in the FIGS. 4 and 5 like parts are provided with the same reference numerals. The rectangle with the reference numeral 82 represents schematically a container in which the liquid is received. If no deposition of gas and / or non-dispersed matter is required, the separation vessel 86 may also be omitted.

In order to incorporate the substance in the liquid, the container is connected to the inlet 81 via the line 88 'and to the outlet 35 via the lines 89' and 85 '. The liquid is passed several times through the dispersing unit 80, in which the substance is added from the supply container 83, and through the container 82 until the desired substance concentration and homogeneity is achieved. The dispersion thus prepared is finally collected in the container 82 and this separated from the dispersion 80. It can be made in a simple manner certain batches of dispersions.

Depending on the application, recirculation of the liquid or of the dispersion by the dispersion unit 80 is not absolutely necessary. The dispersing unit 80 may be e.g. be arranged in a processing line, in which liquid is continuously supplied through the inlet 81 and material through the inlet 30 of the dispersion 80 and mixed and the resulting dispersion is supplied via the outlet 35 for further processing.

The dispersing device according to the invention can be used in a variety of ways to produce material in one Liquid to disperse. The substance may be in solid, liquid or gaseous phase or as a mixture of different phases. In particular, the dispersing device according to the invention is suitable for dispersing flowable solid substances, eg powders, dyes, fillers, substances from the food industry and / or generally insoluble substances, eg difficultly wettable powder, such as metallic powder.

• Die Ausgestaltung des Flügelrades ist an die zu erzeugende Strömung in der Dispergierkammer angepasst. Figuren 6 und 7 zeigen eine Variante des Flügelrades 12', bei welcher die Flügel 93 schräg zur Rotationsachse angeordnet sind. Diese Anordnung erlaubt es, besonders turbulente Strömungen in der Dispergierkammer 10 zu erzeugen und so die Vermischung des Stoffes in der Flüssigkeit zu begünstigen.
• Die Form der Öffnungen 30, 35 und 40 braucht nicht genau so zu sein, wie in Fig. 2 gezeigt. Fig. 8 zeigt eine Variante, bei welcher die Form des Stoffeinlasses 30' und des Auslasses 35' sichelförmig ist, wobei die jeweils vordere Kante 34 bzw. 44 im Wesentlichen gerade ist. Der Flüssigkeitseinlass 40' ist im Wesentlichen viereckig.
• Es ist auch denkbar, mehrere Stoffeinlässe 30, 30', Auslässe 35, 35' und/oder Flüssigkeitseinlässe 40, 40' vorzusehen, die in geeigneter Weise in den Zonen mit Überdruck bzw. Unterdruck oder in der neutralen Zone angeordnet sind.
• Anstelle einer exzentrischen Anordnung des Flügelrades 12, 12' ist es auch denkbar, die Wandung 11 ellipsenförmig auszugestalten und das Flügelrad 12, 12' in der Mitte anzuordnen. Bei dieser Ausgestaltung der Dispergierkammer 10 ergeben sich vier neutrale Zonen, wo weder eine Saugnoch eine Pumpwirkung erzeugt wird, sowie jeweils zwei Zonen mit Überdruck bzw. Unterdruck.
• Die Wandung 11 der Dispergierkammer 12 kann aufgeraut und/oder mit zusätzlichen Schikanen in Form von Vertiefungen und/oder hervorspringenden Elementen versehen sein. Dadurch kann auch Nahe der Wandung 11 eine turbulente Strömung erzeugt werden und so der Flüssigkeitsaustausch innerhalb des Flüssigkeitsrings 47 begünstigt werden. Dies ist besonders bei schweren Stoffen vorteilhaft, da ein Aufkonzentrieren im äusseren Bereich des Flüssigkeitsringes 47 vermieden wird.
• Je nach Bedarf kann es erforderlich sein, anstelle eines Dispergierwerkzeugs 61 mehrere Dispergierwerkzeuge zu verwenden, um die Flüssigkeit und den darin enthaltenden Stoff in geeigneter Weise bearbeiten zu können.

From the foregoing description, numerous modifications will be apparent to those skilled in the art without departing from the scope of the invention, which is defined by the claims. So the following modifications or extensions are conceivable:

• The design of the impeller is adapted to the flow to be generated in the dispersing chamber. FIGS. 6 and 7 show a variant of the impeller 12 ', in which the wings 93 are arranged obliquely to the axis of rotation. This arrangement makes it possible to generate particularly turbulent flows in the dispersion chamber 10 and thus promote the mixing of the substance in the liquid.
• The shape of the openings 30, 35 and 40 need not be exactly as in Fig. 2 shown. Fig. 8 shows a variant in which the shape of the material inlet 30 'and the outlet 35' is crescent-shaped, wherein the respective front edge 34 and 44 is substantially straight. The liquid inlet 40 'is substantially quadrangular.
• It is also conceivable to provide a plurality of material inlets 30, 30 ', outlets 35, 35' and / or liquid inlets 40, 40 ', which are suitably arranged in the zones with overpressure or underpressure or in the neutral zone.
• Instead of an eccentric arrangement of the impeller 12, 12 ', it is also conceivable to design the wall 11 elliptical and to arrange the impeller 12, 12' in the middle. In this embodiment of the dispersion chamber 10 there are four neutral zones, where neither a suction nor a pumping action is generated, and two zones each with overpressure or negative pressure.
• The wall 11 of the dispersing chamber 12 may be roughened and / or provided with additional baffles in the form of recesses and / or protruding elements. As a result, a turbulent flow can also be generated close to the wall 11 and thus the fluid exchange within the fluid ring 47 can be promoted. This is particularly advantageous for heavy materials, since a concentration in the outer region of the liquid ring 47 is avoided.
• Depending on requirements, it may be necessary to use a plurality of dispersing tools instead of a dispersing tool 61 in order to be able to process the liquid and the substance contained therein in a suitable manner.

Claims (10)

1. Device for dispersing a substance in a liquid, with at least one dispersing chamber (10) that has

   at least one liquid inlet (40, 40'),

   at least one substance inlet (30, 30'), and

   at least one outlet (35, 35'), characterised in that

   an impeller (12) having vanes (14) that are rigidly connected to a shaft (19) is arranged in the dispersing chamber (10), and in that,

   in the dispersing chamber (10), a liquid ring (47) can be formed from a liquid that is fed via the liquid inlet (40, 40') into the dispersing chamber (10), and cavities (50-56) can be formed therein which the liquid ring (47) limits,

   the impeller (12) being eccentrically arranged in the dispersing chamber (10) or the dispersing chamber being elliptically shaped in order to vary the respective volume of the cavities (50-56) such that they cause substance to be sucked in through the substance inlet (30, 30') and the liquid wetted substance to be expelled through the outlet (35, 35').
2. Device according to claim 1, characterised in that it comprises a second dispersing chamber (60) that is fluidically connected to the liquid inlet (40, 40') or to the outlet (35, 35') or to both and that comprises at least one dispersing tool (61).
3. Device according to claim 2, characterised in that the dispersing tool (61) comprises a rotor (62) and a stator (63).
4. Device according to claim 2 or 3, characterised in that the dispersing tool (61) and the impeller (12) are arranged on the same shaft (19).
5. Device according to one of claims 1 to 4, characterised in that the impeller (12) has vanes (93) that are arranged obliquely to the rotation axis of the impeller.
6. Device according to one of claims 1 to 5, characterised in that the outlet (35, 35') or the substance inlet (30, 30') or both are sickle-shaped.
7. Device according to one of claims 1 to 6, characterised in that it comprises pumping means (61) for pumping liquid through the liquid inlet (40, 40') into the dispersing chamber (10).
8. Device according to one of claims 1 to 7, characterised in that the outlet (35, 35') is connected to a container (86) for the separation of gas and/or substance.
9. Device according to one of claims 1 to 8, characterised in that the position of the liquid inlet (40, 40') is variably arranged for adjusting the mixing ratio of substance and liquid.
10. Device according to one of claims 1 to 9, characterised in that the outlet (35, 35') has an outer edge (38) that lies on a circle (39), the substance inlet (30, 30') being arranged within this circle.

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