EP2129454B1 - Jet disperser - Google Patents

Abstract

A jet disperser for the fine mixing or dispersing of fluid media has a housing (7, 9, 10), in which a process chamber (1) is disposed for mixing the fluid media. At least two gaps (2a, 2b) extending substantially perpendicular to the longitudinal axis of the process chamber, the gaps also being connected to at least one further feed/discharge channel (3a, 3b) for a fluid medium, end substantially radially in the process chamber via a gap opening. A piston (5) is introduced in the process chamber, wherein the piston can be rotated about a rotational axis (6) and carries an arrangement of openings connected to the process chamber (1) at the height of the gap openings such that the gap openings (2a, 2b) are closed by the piston depending on the angular position of the piston (5) to a higher or lesser degree. In this manner, it is possible to effortless continuously vary the inflow cross-section of the gap (2a, 2b), thus enabling a reproducible, and moreover a particularly fine mixing or dispersing of the fluid media at a low expenditure of energy, even if the mass flows of the reactants vary.

Description

The invention relates to a jet disperser with which fluid media can be mixed particularly finely and liquid mixtures subjected to high shear stresses, e.g. to produce finely dispersed emulsions or suspensions.

One method of producing particularly finely dispersed emulsions and suspensions is to premix the starting components of the dispersion and to promote the resulting predispersion at high pressure through one or more narrow orifices (nozzles). It is known that the pressure drop and thus the specific energy input via the nozzle or the nozzle system, which is required to achieve a certain dispersing result, decreases in most cases while reducing the characteristic dimensions (for example hydraulic diameter) of the nozzle used. In order to efficiently disperse larger mass flows, it is therefore preferable to resort to systems with many particularly fine openings through which they flow in parallel. Furthermore, in order to realize a good dispersing result with a low energy consumption even with variable mass flows of the starting materials with a given dispersing device, some dispersing apparatuses are also equipped with a device for varying the number of apertures through which they flow.

For example, from the EP 0 685 544 a jet disperser is known in which the fluids to be mixed pass through radially extending bores into a process space. The bores can be completely or partially closed by means of an axially displaceable tube or piston guided inside the process chamber, in order to adapt the number of bores through to the desired pressure and throughput, whereby a good fine mixing of the fluid media is to be achieved.

A disadvantage of such a jet disperser is that the total cross section of the openings through which flows through can no longer be varied continuously but only gradually in the case of small mass flows and is ultimately limited by the minimum achievable bore cross section. It is also associated with high technical effort, a lot of holes with diameters well below 0.1 mm, as they would be desirable for many applications, in the walls of the process space bring, which at the same time have a considerable strength due to the high pressure loads. Finally, during operation, the piston, which closes the nozzle openings in the wall of the process chamber, has high forces in the direction of its axis of motion, which must be held by a suitable device in order to prevent undesired displacement of the piston. It is thus at least extremely difficult to produce particularly finely dispersed emulsions and suspensions in processes with varied or fluctuating flow rates with low energy consumption.

The US 2005/072300 A1 also describes a jet disperser for fine mixing of fluid media, but does not disclose that its gap height is variably adjustable.

It is therefore an object of the invention to provide a jet disperser, with which in processes with varied or fluctuating flow rates particularly finely dispersed mixtures can be produced with low energy consumption.

The object has been surprisingly achieved by the features of claim 1. Advantageous embodiments of the invention are specified in the subclaims.

The jet disperser according to the invention for fine mixing or dispersion of fluid media has a housing in which a process space for mixing the fluid media is arranged, which is in communication with a Zu-Abführkanal for a fluid medium. At least two columns extending substantially perpendicularly to the longitudinal axis of the process space, which are each also in connection with at least one further in-discharge channel for a fluid medium, respectively open into the process space via a gap opening substantially radially. In the process space, a rotatable about an axis of rotation piston is introduced, which carries at the level of the stomata an array of openings with connection to the process space such that the stomata are closed depending on the angular position of the piston to a greater or lesser extent by the piston and the gap height of the first gap and the second gap is variably adjustable by spacers.

In the jet disperser according to the invention, it is not disadvantageous if the gap in the circumferential direction relative to the height is relatively wide, since the gap opening can be reduced by the piston to a particularly small passage cross-section, wherein the outlet cross-section in a first application at the right end of can be located on the right side and in a second application at the left end of a gap, so that despite occurring signs of wear, the life of the jet disperser can be extended. Due to the possibility of setting a particularly small outlet cross section, extremely high shear forces can be achieved even at relatively low pressure drops via the jet disperser, which lead to a particularly fine dispersion of the fluid media. Furthermore, by varying the outlet cross-sections of the stomata, the jet disperser according to the invention can be easily adapted to different system and process parameters, such as, for example, pressure or mass flow of educt fluids. This can also be done automatically with the aid of a control loop.

Because the columns of a preferred embodiment can be formed by two housing parts in the jet disperser according to the invention, it is possible with little manufacturing effort to provide gaps which have an extremely low height in the axial direction. For example, it is possible to mill recesses of a few micrometers in depth into one of the housing parts along the abutting edge adjacent to the process space, or by other manufacturing techniques such as grinding, lapping or forming sets, which then cover by a counter surface of the second Housing part define the dispersing column towards the process room. Elaborate microfabrication techniques are in principle not required for this.

The inventive design with the aforementioned spacers, the gap height can be set variably depending on the application. Preferably, the spacers are designed in the form of a foil, so that it is possible to produce gaps with a gap height of a few micrometers by using preferably metallic or polymeric foils with a layer thickness of a few micrometers thick. Particularly preferably, the two housing parts are connected to each other in such a way that leaks even at high pressures to, for example 200 bar, are avoided. For this purpose, for example, self-reinforcing elastomer seals are provided between the housing parts.

Preferably, the piston can be determined in particular steplessly in its angular position, so that the size of the opening into the process space gap openings of the columns variable - preferably from near zero to its full length - can be adjusted. The locking of the angular position of the piston can take place with a comparatively simple device (for example locking screw, clamping jaws), since only very small pressure forces act on the piston during operation of the jet disperser in its direction of movement. It is thus also possible to adjust the angular position of the piston during operation of the jet disperser with little effort. If the adjustment of the angle of the piston by hand, so this preferably takes place by means of a transmission with over- or reduction, so that the piston with high accuracy and reproducibility - preferably of about 2%, more preferably less than 0.5% of Angular opening of the column - can be positioned in a certain angular position. This is achieved, for example, in that the piston has a protruding lever, wherein the lever can be locked. Instead of a lever, a rotary head or the like may be provided. Particularly preferably, the lever or knob cooperates with a scale, so that the angular position of the piston can be read on the jet disperser. Also possible is a motorized adjustment of the angular position of the piston, e.g. by a mechanical, electrical, magnetic, pneumatic or hydraulic drive. Such an embodiment of the jet disperser according to the invention is particularly preferable if the angular position of the piston is to be defined via a control loop, e.g. to keep the pressure drop across the jet disperser or other process characteristic constant with varying media streams or media properties.

Preferably, the arrangement of the gaps and in particular of the gap openings to the process chamber in a common plane perpendicular to the axis of rotation of the piston and the openings in the piston are in this plane in direct (ie straight) connection. Particularly preferably, the stomata of the gaps are arranged in pairs opposite to each other. This makes it possible that the fluids to be mixed immediately after entering the process space in the center of which collide, resulting in a particularly good mixing or dispersion due to the higher turbulence and the higher shear forces. In particular, if more than two columns are used, for example, to mix more than two fluids, the columns are arranged in such a way that two columns each are arranged in pairs opposite one another. In order to achieve the most symmetrical flow possible in the process space, an even number of columns is therefore preferably provided. In this case, if an odd number of fluids are to be mixed or a premixed system is to be homogenized, the flow rate of at least one of the fluids may be split into two columns. The width of the stomata is preferably the same for all columns and the piston or the openings therein are preferably shaped such that in each angular position of the piston of each stomata each same portion is closed. This is achieved, for example, in that the edges of the areas of the piston covering the stomata openings are at the same angular positions with respect to one another as the corresponding end edges of the respectively concealed stomata.

If two fluid media are to be mixed or dispersed with approximately equal mass flows, the gaps are preferably respectively connected to supply channels in order to be charged with the fluid media to be supplied, while the process chamber is connected to a discharge for the fluidic product. This mode of operation of the jet dispersant according to the invention is particularly suitable, for example, for producing emulsions having approximately equal proportions of the oil and water phases, e.g. in the manufacture of cosmetics, detergents and cleaners, lubricants, in continuous extraction processes, or in the performance of phase transfer reactions, e.g. in the emulsion polymerization or the production of core-shell particles. In this mode of operation, solid particles, in particular nanoparticles, can also be advantageously produced by precipitation from two or more reactive fluid starting materials with the jet disperser according to the invention.

If appropriate, the first gap and the second gap can also be acted upon by the same medium to be supplied, while the process space has an outflow for the fluidic product is connected. This is particularly advantageous when the fluid medium to be supplied is already partly predispersed in a preceding process step, so that fine dispersion takes place in the jet disperser according to the invention or in a plurality of parallel jet dispersants in a final step. This mode of operation is suitable, for example, for the homogenization of emulsions or the comminution of solid particles or aggregates in fluid media.

It is also possible that one of the columns and the process space are each supplied with a fluid medium to be supplied and another gap is connected to a drain, via which the mixture formed in the process space flows. This mode of operation is particularly preferred when the fluid medium fed into the process space has a significantly higher volume flow or a substantially different viscosity than the fluid medium supplied via the gap or if a two-stage dispersion is required to achieve a desired mixing or dispersion result (or mixing and homogenization) is necessary, especially if in this case the product of the predispersing is particularly unstable. In this operating mode, since the fluid medium supplied via the gap is admixed with the medium supplied in the process space with the participation of high shear and inertial forces, predispersion is achieved in the process space. The thus predispersed medium is additionally dispersed or homogenized by the subsequent outflow via the second gap. The residence time of the mixture between the two dispersion steps can be kept extremely short by using a very small process chamber volume. Advantageous application of the jet disperser according to the invention in this mode of operation again in the production of emulsions and solid dispersions, such as in the production of cosmetics, detergents and cleaners, lubricants, paints and pigments, in continuously operated extraction processes, the implementation of phase transfer reactions such as in the Emulsion polymerization or in the production of particles by precipitation (for example, core-shell or nanoparticles), especially when mixed or dispersed in the underlying processes fluids having significantly different volume flows or viscosities or short residence times between premixing and homogenization / dispersion are beneficial to the process.

Due to the compact, stable construction of the jet disperser according to the invention, it is possible that the media to be supplied can have a pressure of 10 to 200 bar or even more. At the same time it is possible to easily achieve gap heights in the range of 1 .mu.m to 500 .mu.m. The gap height is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm. The process space has orthogonal to the axis of rotation an effective diameter of in particular 0.2 mm - 10 mm, preferably 0.4 mm - 5 mm and particularly preferably 1 mm to 2.5 mm. The effective diameter of the process space results in an optionally not completely round cross-sectional area in that the diameter of a circular area is calculated with an area size that corresponds to this cross-sectional area.

An enlargement of the gap cross-sections provided for the various flow rates in the process, which could be desirable, for example, in the case that a higher mass flow of the educts is to be dispersed than is possible with a given jet disperser according to the invention under fully open gaps under given process conditions, can possibly while maintaining the gap height and the diameter of the process space can be achieved in that arranged around the process space more Spaltanordungen preferably the same geometry and angular position along the axis of rotation of the piston and in the same way in each plane with common supply and discharge channels for the respective fluid media get connected. In this way, a flow geometry of the jet disperser, which has been found to be advantageous for a particular process, can be scaled up with high design and manufacturing effort even for higher flow rates of the process media.

The invention will be explained in more detail with reference to the accompanying drawings.

Fig. 1a

eine schematische Schnittansicht eines erfindungsgemäßen Strahldispergators in einem ersten Betriebsmodus

Fig. 1b

eine schematische Querschnittansicht des in Fig. 1a dargestellten Strahldispergators

Fig. 1c

eine schematische Schnittansicht des in Fig. 1 a dargestellten Strahldispergators in einem zweiten Betriebsmodus

Fig. 1d

eine schematische Querschnittansicht des in Fig. 1c dargestellten Strahldispergators

Fig. 2a

eine schematische Querschnittansicht des erfindungsgemäßen Strahldispergators in einer weiteren Ausführungsform in einem ersten Betriebsmodus

Fig.2b

eine schematische Querschnittansicht des in Fig. 2a dargestellten Strahldispergators in einem zweiten Betriebsmodus

Fig.2c

eine schematische Querschnittansicht des in Fig. 2a dargestellten Strahldispergators in einem dritten Betriebsmodus

Fig. 2d

ein schematische Querschnittansicht des in Fig. 2a dargestellten Strahldispergators in einem vierten Betriebsmodus.

Show it:

Fig. 1a

a schematic sectional view of a jet disperser according to the invention in a first operating mode

Fig. 1b

a schematic cross-sectional view of in Fig. 1a illustrated jet disperser

Fig. 1c

a schematic sectional view of the in Fig. 1 a jet disperser shown in a second mode of operation

Fig. 1d

a schematic cross-sectional view of in Fig. 1c illustrated jet disperser

Fig. 2a

a schematic cross-sectional view of the jet disperser according to the invention in a further embodiment in a first operating mode

2b

a schematic cross-sectional view of in Fig. 2a illustrated jet disperser in a second mode of operation

Figure 2c

a schematic cross-sectional view of in Fig. 2a illustrated jet disperser in a third mode of operation

Fig. 2d

a schematic cross-sectional view of in Fig. 2a illustrated jet disperser in a fourth mode of operation.

An in Fig. 1a illustrated inventive jet disperser has a housing of the housing parts 7, 9, 10, in which a process chamber 1 is formed. In the exemplary embodiment shown, the discharge channel 4 can also be operated as a feed channel and is therefore further referred to as the discharge channel 4. The housing has a first housing part 7 and a second housing part 9, between which by means of spacers 8 (in the illustrated embodiment, the spacers are a spacer film) columns 2a and 2b are formed. The gaps 2a, 2b are each acted upon by channels 3a, 3b with a fluid medium to be mixed. These Channels can also be operated to supply channels or discharge channels and are therefore called either to-discharge channels or depending on the mode of operation and discharge channels on.

Within the housing, a piston 5 is arranged axially, which is rotatably mounted about a rotation axis 6. The storage is via a bearing 11, which may be, for example, a plain bearing. The bearing 11 is arranged in the illustrated embodiment in a third housing part 10.

The rotatable piston 5 has, at the level of the gaps 2a and 2b, an opening which communicates with the process space 1 ( Fig. 1b ). Depending on the angular position of the piston 5, the gap openings of the first gap 2a and of the second gap 2b opening into the process space 1 can be partially closed in order to adjust a gap opening adapted to the mass flow of the media to be dispersed. Because of the particularly small height of the stomata, which can be set independently of the gap width, high shear and inertial forces occur in the gap and at the outlet, which cause a particularly finely dispersed emulsion or a high particle or agglomeration comminution in suspensions. The medium dispersed in the process space 1 emerges after mixing via the inlet-to-discharge channel 4 connected to the process space 1.

Preferably, the gaps 2a, 2b are the same width (measured along the circumference of the process space) in order to achieve the simplest possible geometry of the jet disperser. In particular, in the case of a plurality of inlet discharge channels 3a, 3b, it can be advantageous if the spacer foil 8 contains columns 2a, 2b of different lengths. In this case, it is sufficient to turn the spacer film 8 in order to connect, with the aid of the longer-running gaps 2a, 2b, previously closed in-discharge channels 3a, 3b which open at a greater radius into the longer-running gaps 2a, 2b. Furthermore, it may be advantageous if the connection opening of the piston 5 can connect fewer columns 2a, 2b to the process space 1 than total columns are present. By a corresponding rotation of the piston 5 in this case, previously closed columns can be opened particularly easily, while at the same time previously opened gaps are closed. This makes it possible, by a simple rotation of the piston 5 other Zu-Abführkanäle 3a, 3b to connect, for example, are applied to another medium. This mode of operation is particularly suitable when different dispersions are to be produced in alternating continuous operation with the same jet disperser.

At the in Fig. 1a and Fig. 1b shown operating mode are fed via the to-discharge channels 3a, 3b and the column 2a, 2b, two different or identical reactants, which are mixed or dispersed in the process chamber 1. This operating mode is particularly suitable when the volume flows of the media to be supplied are about the same size or when a solid product is precipitated during the mixing of the media. Since the supplied media are aligned in the connecting opening of the piston 5 to one another, a particle agglomeration of the precipitated solids or the solid particles already contained in the supplied streams is avoided or the existing particles or emulsion drops are even crushed.

At the in Fig. 1c and Fig. 1d shown operating mode is the same in Fig. 1a and Fig. 1b illustrated jet disperser used. Compared to the in Fig. 1a and Fig. 1b shown operating mode is in the in Fig. 1c and Fig. 1d shown operating mode, the connection of the Zu-Abführkanals 3b or the gap 2b and the Zu-Abführkanal 4 reversed. This means that an educt is in each case supplied via the to-discharge channel 4 and the to-discharge channel 3a or gap 2a which is dispersed in the process chamber 1 and discharged through the gap 2a, wherein the transition from the gap 2b in the Zu-Abführkanal 3d a further dispersion takes place. This mode of operation is particularly suitable if an educt with a low volume flow to the educt with a high volume flow, which is supplied via the to-discharge channel 4, to be mixed, or if between the pre-mixing and the dispersion or Homogenization a particularly short residence time should be realized. For example, this operating mode is preferably suitable for processing reactive multiphase systems, since a reaction can take place only during the mixing of the fluids in the process space and only a short contact time is present until further dispersion or homogenization of the product mixture.

Both at the in Fig. 1a and Fig. 1b shown operating mode and in the in Fig. 1c and Fig. 1d shown operating mode can be adjusted via the angular position of the piston 5, the size of the mouth opening of the columns 2a, 2b, so that even with varying flow rates, the inlet velocity, the pressure drop, the shear rate, etc. can be kept substantially constant. Since hydrostatic forces acting on the piston only in the axial and radial directions, while in the azimuthal direction, if any, only slight hydrodynamic forces occur, only a small torque must be expended to open the gap openings of the columns 2a, 2b and close or to fix the position of the piston.

At the in Fig. 2a a total of four columns 2a, 2b, 2c, 2d are provided, which are each acted upon by a different educt A, B, C, D. The educts A, B, C, D mix in the process chamber 1 and are discharged as finely dispersed product P via the process chamber channel 4. However, it is also possible to supply only two reactants A, B via the four columns 2 a, 2 b, 2 c, 2 d, which are each fed via two opposing columns ( Fig. 2b ). The number of columns 2a, 2b, 2c, 2d need not necessarily coincide with the number of reactants A, B, C, D to be supplied. It is even possible for all four columns 2a, 2b, 2c, 2d or even more columns to be charged with only one, for example, predispersed starting material.

At the in Fig. 2c shown operating mode is compared to in Fig. 2a shown operating mode, a starting material D supplied via the Zu-discharge channel 4, while the other reactants A, B, C are supplied via the Zu-Abführkanäle 3a, 3b, 3d and the respective columns. The product P is discharged via the gap 2c and the to-discharge channel 3c. In this operating mode, too, it is possible for one or more educts A, B, C, D to be supplied via at least two gaps 2a, 2b, 2c, 2d or to the exhaust duct 4 and at least one further gap 2a, 2c, 2d. Moreover, it is possible to discharge the product P over at least two of the columns 2a, 2b, 2c, 2d and the corresponding in-discharge ducts 3a, 3b, 3c, 3d ( Fig. 2d ). Furthermore, any combination is possible in which one of the educts A, B, C, D or the product P is supplied or removed via more than one of the inlet discharge channels 3a, 3b, 3c, 3d, 4.

Claims (12)

1. Jet disperser for the fine intermixing or dispersion of fluid media, with a housing, with a process space (1), arranged in the housing, for intermixing the fluid media, with a first gap (2a) issuing radially via a first gap orifice into the process space (1) and running perpendicularly with respect to the longitudinal axis of the process space, and with a second gap (2b) issuing radically via a first gap orifice into the process space (1) and running perpendicularly with respect to the longitudinal axis of the process space, characterized in that a piston (5) rotatable about an axis of rotation (6) is introduced into the process space (1) and carries, level with the gap orifices, an arrangement of orifices with a connection to the process space, in such a way that a greater or lesser fraction of the gap orifices is closed by the piston, depending on the angular position of the latter, further characterized in that the gap height of the first gap (2a) and of the second gap (2b) can be set variably by means of spacer pieces (8).
2. Jet disperser according to Claim 1, characterized in that the process spacer is of rotationally symmetrical, preferably cylindrical design.
3. Jet disperser according to Claim 1 or 2, characterized in that the housing has a first housing part (7) and a second housing part (9), between which the gaps (2a, 2b) are formed.
4. Jet disperser according to one of Claims 1 to 3, characterized in that the spacer pieces (8) are in film form.
5. Jet disperser according to one of Claims 1 to 4, characterized in that an even number of gaps (2a, 2b, 2c, 2d) is provided, and the gap orifices of the first gap (2a, 2c) and of the second gap (2b, 2d) are in each case arranged opposite one another in pairs.
6. Jet disperser according to one of Claims 1 to 5, characterized in that the first gap (2a) and the second gap (2b) are connected in each case to a supply duct for a fluid medium to be supplied, and the process space (1) is connected to a discharge duct (4).
7. Jet disperser according to Claim 6, characterized in that the first gap (2a) and the second gap (2b) are acted upon with the same fluid medium to be supplied.
8. Jet disperser according to one of Claims 1 to 5, characterized in that the first gap (2a) and the process space (1) are connected in each case to a supply duct (3a and 4) for a fluid medium to be supplied, and the second gap (2b) is connected to a discharge duct (3b).
9. Jet disperser according to one of Claims 1 to 8, characterized in that the media to be supplied have a pressure of 10 to 200 bar which is reduced when they flow through the gaps.
10. Jet disperser according to one of Claims 1 to 9, characterized in that the gaps (2a, 2b) have in the axial direction a height of 1 µm to 500 µm, preferably of 5 µm to 200 µm, especially preferably of 10 µm to 100 µm.
11. Jet disperser according to one of Claims 1 to 10, characterized in that the process space (1) has orthogonally with respect to the axis of rotation (6) an effective diameter of 0.2 mm - 10 mm, preferably of 0.4 mm - 5 mm, especially preferably of 1 mm - 2.5 mm.
12. Jet disperser according to one of Claims 1 to 11, characterized in that the arrangement of the gaps (2a, 2b) is repeated with the same geometry and angular orientation in a plurality of planes along the axis of rotation (6) of the piston (5), and gaps corresponding in terms of their angular position are in each case connected in the various planes to the same supply/discharge duct (3a, 3b).

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