DE19927556C2 - Static micromixer and method for statically mixing two or more starting materials - Google Patents

Description

The invention relates to a static micromixer for two or More starting materials according to claim 1 and a method for static mixing of two or more starting materials according to claim 12.

Micromixers form a main component of so-called microreactors have three-dimensional microstructures in which chemical Implementations are carried out. The grow in importance Microreactors for example in combinatorial chemistry for Production of emulsions and gas liquid dispersions and in the Gas phase catalysis.

With static mixers, mixing is done by dividing the fluid into Partial streams and recombining of the partial streams accomplished. at Dynamic mixers, on the other hand, are mixed using, for example Stirrer mainly about convection. Often static micromixers point very complex microstructures that can easily be damaged and are difficult to clean.

A static mixer that is simple and inexpensive to manufacture can be cleaned easily, is presented in US Pat. No. 4,514,095. The one there Mixer has a tubular container with one inlet and one Discharge opening in its cover or base plate. In this tubular containers are circular mixing plates with Passage openings stacked on top of each other. An introduced educt stream which  can consist of any number of different starting materials, is by a first mixing plate into a central and several peripheral flows split. In the next mixing plates, the previously formed ones are formed Peripheral currents passed through without change, while the central Educt flow via star-shaped channels, towards the plate edge run, and via peripheral through openings in further peripheral currents is split up. The entirety of the peripheral currents is then united again into a central stream. This mixing process is in several mixing zones continued according to the current flow described above.

However, this mixer has a serious disadvantage: by one To achieve as homogeneous a degree of mixing as possible, very many Mixing zones can be connected in series. The reachable also depends Degree of mixing depends on how good the educts are before they are fed were premixed. The situation is particularly problematic if between the reactants different reactions with different Speeds run side by side, especially when the Diffusion rate less than one or more of the Reaction rates is. This can decrease the Selectivity and thus the yield.

The object of the present invention is to provide a micromixer or to carry out a process which allows starting materials to be produced in the shortest possible time to mix as homogeneously as possible, and which also allow reactions whose Reaction rate is high compared to the diffusion rate, to be targeted.

This object is achieved according to claim 1 by a static micromixer for n (n ≧ 2) Educts of a housing with n fluid supply and a fluid discharge and n or more plates arranged in a stack in the housing, the plates having recesses in the millimeter to submillimeter range  have, which together a main channel for discharging the product and form at least n secondary channels for feeding each individual educt, the extend in the stacking direction through the entire stack, and wherein in at least n the Plates for the formation of mixing plates for a starting material one or more elongated recesses in the millimeter to submillimeter range that are each from the main channel to the secondary channel or channels extend this educt.

The object is also achieved according to claim 12 by a method for static mixing solved two or more starting materials, which is characterized in that at least one main stream is formed from each educt, from which at least one Branch is branched off, and the substreams of all educts in one Product stream are combined, the individual educt streams of the series after alternately in the form of the product stream that fluid lamellae in Flow direction are stacked, this diffuse into each other.

This method can be carried out with the device according to the invention as follows:
Each educt is fed to the micromixer and distributed to at least one secondary channel. The main educt streams flow in the secondary channels. At the location of a secondary channel, where a mixing plate has an elongated recess that extends from precisely this secondary channel to the main channel, at least a partial stream of this starting material is branched off from the main stream and led to the main channel. The product flow flows in the main channel.

The fluid layer thickness or droplet size, for emulsions or Dispersions of the educts fed to the product stream are mainly determined by the thickness of the mixing plates. The lateral dimensions of the Recesses are irrelevant and comparatively large. A you can achieve particularly good and fast homogeneous mixing  in that the pressure drop of the main streams is approximately equal to that Pressure drop in the product flow is small compared to that Pressure drop of the partial flows. Through these measures and through the Sequential alternate feeds of the educt streams are in the main channel Fluid slats of small thickness stacked on top of each other in the direction of flow, because of the small slat thicknesses even at lower ones Diffusion speeds can diffuse into each other very quickly. Typical slat thicknesses and thus also mixing plate thicknesses are between 1 to 300 µm, advantageously between 5 and 70 µm.

The homogenization and mixing effect of the mixer can be achieved Reduce the mixing plate thickness even more. It is advantageous about the Mixing plate thickness, the layer thickness of the partial streams set such that the Mixing mainly by diffusion and to a lesser extent by Convection takes place.

In principle, it is sufficient to have a mixing plate for each educt, but the Throughput with constant pressure loss gets a lot bigger if you go up to several hundred of these plates stacked on top of each other. Because of the low The entire stack is only a few millimeters thick high. By the ratio of the lateral dimensions of the recesses to Thickness of the mixing plates also ensures that the micromixer according to the invention has a high throughput (for example approx. 5 l / h) with a low pressure drop (e.g. a maximum of 200 hPa for aqueous media) allowed.

The structures in the panels can be inexpensively punched, Punching, injection molding, etching or cutting using a laser or also manufacture by wire coding in batches.  

To increase the throughput even further, a larger number can also be used are connected in parallel by micromixers according to the invention. By the The micromixer according to the invention opens up very high throughput numerous applications in production processes in the chemical industry.

It has proven advantageous to have the main channel centrally along the Arrange stacking axis. The secondary channels are on the outside around the main channel arranged around. If there are several secondary channels for an educt in one Mixing plate, they are best equidistant from the main line arranged to have the same pressure drop in all partial flows of the educt guarantee. The elongated recesses in which the partial flows flow extend radially from the main channel to the respective secondary channel.

It has proven to be particularly advantageous if the arrangement of the Recesses in the individual mixing plates are rotationally symmetrical to the stacking axis is. This not only has a positive effect on the pressure drop, but also also simplifies the manufacture of the individual panels. Because it can now Identical single plates are used, which twisted against each other supply individual individual plates with different starting materials.

In a preferred embodiment, one or more are the end faces of the stack-forming plates are designed as distributor plates. This one or several distributor plates have depending on the number of secondary channels for the respective educt on one or more recesses, which differ from the Fluid supply of this educt to the or the secondary channels of this educt extend. Depending on the number of starting materials and number of distributor plates or after whether the fluid discharge is also on the specific end face of the stack is arranged for the product stream, which is connected to the main channel stands, a distributor plate also has further recesses to form the Secondary channels of the other educts and / or the main channel. The Distribution plates help to ensure that the starting materials are even and with as much as possible  low pressure loss from the fluid feeds to the secondary channels distribute and the mixed product to avoid subsequent reactions dissipate as quickly and free of dead volume as possible.

A starting material distribution which is as uniform as possible can be achieved if the fluidic resistances in the recesses of the distributor plates small compared to the fluidic resistances in the elongated recesses of the Mixing plates are. This is preferably achieved in that the Plate thickness of the distributor plates is large compared to the plate thickness of the Mixing plates is.

In a further preferred embodiment there is between at least two An intermediate plate arranged for each secondary channel and mixing plates the main channel has exactly one recess. Preferably located such an intermediate plate between all mixing plates. By the Inserting the intermediate plate goes through the product stream a short Section of the main channel in which the already in the product stream existing starting materials can mix before the next starting material is fed becomes.

The recess for the main channel preferably has in the intermediate plate a smaller cross-sectional area than the corresponding recess in the Mixing plate arranged upstream in the direction of flow. This ensures that the educt is evenly distributed over the circumference of the main channel. There the mixing plates following in the direction of flow are the starting materials in the Feed plate level offset by an angle, there is a risk that store the educts together in axial strips (as with toothpaste). By the Insert an intermediate plate with a narrower main channel recess ensures that only the partial flows flow together and then that Educt from all sides evenly on the smaller recess in the  Intermediate plate to move and doing so over the circumference of the recess steady flow developed.

It is best for the pressure and flow conditions if the Plate thickness of the intermediate plates the plate thickness of the mixing plates correspond. It also avoids that the dimensions of the Micromixers get too big.

A mental fusion of the mixing and intermediate plates creates one Combination plate, but not the breakthroughs for main and secondary channels continuous elongated recesses (depressions) between the Main channel breakthrough and the secondary channel breakthroughs. Therefor Particularly suitable manufacturing processes are stamping or stamping Injection molding.

In a special embodiment of a combination plate, two or more elongate recesses branch off from the secondary duct opening, so that two or more partial streams branch off from the main stream of the educt and are fed to the main duct. It is also conceivable that the recess connecting the secondary channel opening to the main channel opening is designed in the manner of the bifurcation cascade. Here, a partial stream is branched off from the main stream of the educt and divided into 2 ⁿ partial streams (n = number of stages of the bifurcation cascade). As a result, the partial flows obtained in this way, which are fed to the product flow, have identical volume flows.

In a further preferred embodiment, one of the starting materials is the Stack fed radially from the outside. They become this educt associated secondary channels formed as recesses on the edge of the plate. The mixing plates, which are the partial flows of this educt, are an exception  to lead. These mixing plates and all other recesses are otherwise prefers openings.

This embodiment is particularly suitable for the mixing of two starting materials. In this case the fluid discharge for the product flow is on arranged on one end of the stack, the feed for the one educt arranged on the other end and the feed for the second educt arranged on the side of the housing. A between the housing inner wall and the The outer wall of the cavity is completely covered by this second one Educt filled in and therefore the second educt from all sides of the stack fed.

For the use of the micromixer according to the invention for strong exothermic or endothermic reactions, it is beneficial if in it Heat exchanger is integrated. For this, either the plates can be additional Have recesses to accommodate cooling or heating pipes. One can arrange such a cooling or heating pipe centrally in the main channel, so that the product flow is led around this heating or cooling pipe. The Panels can also be against each other, for example by diffusion soldering or Diffusion welding, be sealed so that there is no need for pipes can and the cooling or heating liquid directly through the additional Recesses can be made.

The present invention is based on the accompanying drawings are explained. Show

Fig. 1 mixing plates for two starting materials,

Fig. 2 mixing plates for four starting materials,

Fig. 3a shows an exploded view of a micro-mixer for two reactants with the individual components in section,

FIG. 3b-h, the individual components of the micro mixer of FIG. 3a,

Fig. 4a shows a first example of a combination plate, and

FIG. 4b shows a second example of a combination plate.

In Fig. 1, a stack 15 of mixing plates 20 a, b for two starting materials A, B is shown. These mixing plates 20 a, b have three recesses 24 a for the educt A and three recesses 24 b for the educt B. The recesses 24 a, b of an educt are each arranged on the corners of an equilateral triangle. The two triangles are indicated by dashed lines. Both triangles are rotated by 60 ° against each other. Therefore, all the recesses 24 a, b lie on a circle (indicated by a dotted line), in the center of which the main channel 23 is arranged. The mixed product flows out via the main channel 23 .

In addition to the recesses 24 a, b and the main channel 23 , each mixing plate 20 a, b has three elongated recesses 25 . These elongate recesses 25 extend from the recesses 24 a or 24 b forming the secondary channels 24 of a starting material radially inward to the main channel 23 , the regions of the elongate recesses 25 in the center of the mixing plates 20 a, b forming the main channel. The arrangement of the recesses 24 a, b, 23, 25 is therefore rotationally symmetrical by 120 ° to the longitudinal axis of the stack 15 , which runs along the main channel 23 . The mixing plates 20 a and 20 b are therefore identical. However, they are alternately arranged one above the other rotated by 180 °. This results in that the recesses 24 a and 24 b forming the secondary channels of the one and the other educt lie congruently one above the other and also the regions of the recesses 25 forming the main channel 23 lie one above the other. In addition, the elongated recesses 25 are arranged such that in the mixing plates 20 a, the starting material A is led from the secondary channels 24 a to the main channel 23 , in the mixing plates 20 b, however, the starting material B is led from the secondary channels 24 b to the main channel 23 .

Thereby, are stacked each starting material in the main channel 23 thin fluid lamellae, whose thickness is determined by the mixing plate thickness. The mixing plate thickness is chosen to be so small, preferably between 5 and 70 μm, that the two starting materials A and B can mix at a rate by diffusion which is higher than the reaction rate of the desired reaction between the starting materials A and B. In the production of emulsions or dispersions, this has the advantage of the smallest droplet sizes with a homogeneous size distribution.

FIG. 2 shows a further stack 15 which is constructed from mixing plates 20 a-d which are now designed for four starting materials A to D. The procedure was analogous to the example shown in FIG. 1. For each educt A to D there are three secondary channels 24 a-d. These secondary channels 24 a-d are in turn arranged on a circle, in the center of which is the main channel 23 . The arrangement of the recesses is again rotationally symmetrical by 120 ° to the axis along the main channel 23 . The individual mixing plates 20 a- 20 are also identical in construction again, but in each case arranged rotated by 90 ° to each other one above the other d. Therefore, the elongated recesses 25 , which connect the secondary channels 24 a-d each of a starting material A to D with the main channel 23 , are arranged such that the starting material A is led to the main channel 23 in the plates 20 a, the starting material B in the mixing plates 20 b is led to the main channel 23 , etc. The mixing plates 20 a-d are arranged one after the other alternately one above the other (a, b, c, d, a, b, c, d, a, b, c, d). This ensures that the product flow is as homogeneous as possible. Due to the equidistant arrangement of the secondary channels 24 a-d to the main channel 23 , the pressure drop in the partial flows of the educts is the same in all elongate recesses 25 , which likewise contributes to homogeneous mixing.

FIG. 3a shows an exploded view of a micromixer which is designed for two starting materials A, B, the starting material B being fed radially to the stack 15 and the starting material A being supplied centrally on the left end face of the stack 15 .

The micromixer consists of the following components, which are also shown individually in FIGS . 3b-h: a housing 10 ( FIG. 3g), two sealing rings 33 , one of which is arranged between the distributor plate 21 and the housing 10 and the another is arranged between the housing 10 and the cover plate 11 , a distributor plate 21 ( FIG. 3h), mixing plates 20 a, b ( FIG. 3d, f), intermediate plates 22 ( FIG. 3e) and the cover plate 11 ( FIG. 3b) , In addition, three adjusting rods 31 are shown (the two lower ones lie one above the other in the drawing), which are required for assembling the mixer.

The housing 10 is designed as a cuboid open on one side. It is hollow on the inside, and the volume removed has the shape of a cylinder. The cavity is arranged in the housing such that an end face of the removed cylinder corresponds to the open side of the cuboid. The fluid supply 12 a for the starting material A is located on the opposite side. The fluid supply 12 b for the starting material B is arranged on one of the four further sides. The educt B is thus fed radially to the cylindrical cavity. Both fluid feeds 12 a, b are arranged approximately in the middle of the respective cuboid side. As will be shown below, all of the plates have essentially a circular base. The stack composed of them therefore has a cylindrical shape and can be inserted into the cavity of the housing. Since the educt B is fed radially, an annular space must be present between the stack 15 and the inner wall of the housing 10 so that the educt B can be distributed evenly around the entire cylinder.

The housing 10 also has bores 34 which, like the fluid supply 12 a, b, are provided with a thread, so that educt lines can be screwed onto the housing 10 . These holes 34 extend through the entire housing 10 and serve to screw the cover plate 11 to the housing. The bores 34 are arranged in the four corners of the housing 10 parallel to the cylinder axis or the stack axis.

A sealing ring 33 and the distributor plate 21 are first introduced into the housing 10 . The distributor plate 21 has a circular recess 26 , on the circumference of which six recesses 24 a are arranged, which form the secondary channels for the starting material A with the corresponding recesses in the remaining plates. The recess 26 is arranged on the side facing the fluid supply 12 a, so that a small collecting chamber for the educt A is formed, from which the educt A flows into the secondary channels 24 a.

For easier stacking of the plates, an adjusting pin 31 is now inserted into three of the recesses 24 a of the distributor plate 21 . The remaining plates 20 a, b, 22 are plugged onto these adjustment pins. Finally, the second sealing ring 33 and the cover plate 11 are pushed onto the adjusting pins and the entire stack is pressed together until the cover plate 11 can be screwed together with the housing 10 . For this purpose, holes 34 are provided in the cover plate 11 on the one hand in the four corners, which can accommodate the screws inserted through the housing 10 , and on the other hand the holes 32 , through which the adjustment pins can be passed. In addition, the cover plate 11 has in its center the fluid discharge 13 for the product flow. The holes 32 and the fluid drain 13 are threaded. After removing the adjustment pins, the holes 32 are closed with screws. A product line can be screwed to the fluid outlet 13 .

In addition to the distributor plate 21, there are three further plate types within the stack 15 : the intermediate plates 22 , the mixing plates 20 a and the mixing plates 20 b. The intermediate plates 22 have small circular recesses 24 a, 23 for the educt A and for the main channel, the six recesses 24 b being arranged on a circle, in the center of which the recess 23 is for the main channel. For the secondary channels for the educt B, the intermediate plates 22 between the recesses 24 a have V-shaped recesses 24 b on the edge of the intermediate plate 22 . These recesses 24 are b on the circle on which the recesses 24 a are for the secondary channels for the starting material A.

V-shaped recesses at the edge of the plate for forming the secondary channels for the starting material B also have the mixing plates 20 a. In addition, they have six elongated recesses 25 which lead the starting material A to the main channel 23 . The six elongated recesses 25 together form a star-shaped recess. The V-shaped recesses 24 b are arranged between the star tips.

A similar star-shaped recess can also be found in the mixing plates 20 b, in which the starting material B is led to the main channel 23 through the star-shaped recess. In the mixing plates 20 b, no V-shaped recesses are arranged between the star tips, but rather circular bores 24 a, which form the secondary channels for the starting material A.

The recess of the intermediate plates 22 forming the main channel 23 has a much smaller cross-sectional area than the star-shaped recesses 23 of the mixing plates 20 a, b. This ensures that only the partial flows of the respective educt flow together and then the educt moves uniformly from all sides towards the smaller recess in the intermediate plate and thereby develops a flow that is uniform over the circumference of the recess. This prevents the educts from lying together in axial strips in the main channel.

In Fig. 4a, a one-piece combination plate 35 a is shown, which has the structure and function of both a mixing plate 20 b and an intermediate plate 22 . The openings 24 a, b for the secondary channels and 23 for the main channel are continuous, the depressions 36 for the elongated recesses 25 are not continuous.

The same applies to the combination plate 35 b in FIG. 4 b, which arises from the conceptual fusion of the mixing plate 20 a and the intermediate plate 22 . Compared to the combination plate 35 a, the openings 24 b are now enlarged into V-shaped recesses 24 c in order to be able to feed the educt B radially from the outside.

Claims (13)

1. Static micromixer for n (n ≧ 2) starting materials, which has a housing ( 10 ) with at least n fluid feeds ( 12 a, b) and a fluid discharge ( 13 ) and n or more in the housing ( 10 ) to form a stack ( 15 ) Arranged plates ( 20 , 21 , 22 ), the plates ( 20 , 21 , 22 ) having recesses ( 24 , 25 ) in the millimeter to submillimeter range, which together have a main channel ( 23 ) for discharging the product and at least n secondary channels ( 24 ) for feeding each individual educt, which extend in the stacking direction through the entire stack ( 15 ), and wherein in at least n of the plates ( 20 a-d) to form mixing plates ( 20 ad) one or more elongate recesses for each educt ( 25 ) in the millimeter to submillimeter range are present, each extending from the main channel ( 23 ) to the secondary channel or channels ( 24 ) of this educt. 2. Micromixer according to claim 1, characterized in that the main channel ( 23 ) is arranged centrally along the stack axis and the secondary channels are arranged outside around the main channel ( 23 ). 3. Micromixer according to claim 1 or 2, characterized in that the arrangement of the recesses ( 24 , 25 ) is rotationally symmetrical to the stack axis. 4. micromixer according to one of claims 1 to 3, characterized in that at least one designed as a distributor plate (21) plate (21) is arranged in the stack (15) at at least one end face of the stack (15), the one or more recesses ( 24 , 26 ), which extend from the fluid feed ( 12 ) of an educt to the secondary channel or channels ( 24 ) of this educt, and optionally further recesses for forming the secondary channels ( 24 ) of the other starting materials and / or the main channel ( 23 ) having. 5. Micromixer according to claim 4, characterized in that the distributor plate ( 21 ) or distributor plates ( 21 ) and the recesses therein ( 24 , 25 ) are designed such that the associated pressure drop is smaller than the pressure drop in the elongate recesses ( 25 ) of the mixing plates ( 20 ). 6. Micromixer according to one of claims 1 to 5, characterized in that between at least two mixing plates ( 20 ) an intermediate plate ( 22 ) is arranged which for each secondary channel ( 24 ) and the main channel ( 23 ) exactly one recess ( 24 ) having. 7. Micromixer according to claim 6, characterized in that in the intermediate plate ( 22 ) the recess for the main channel ( 23 ) has a smaller cross-sectional area than the corresponding recess in the mixing plate ( 20 ) arranged upstream in the flow direction. 8. Micromixer according to claim 6 or 7, characterized in that the plate thickness of the intermediate plate ( 22 ) or intermediate plates ( 22 ) corresponds to the plate thickness of the mixing plates ( 20 ). 9. Micromixer according to one of claims 1 to 8, characterized in that the one or more secondary channels ( 24 ) of an educt-forming recesses ( 24 b) are formed as recesses on the edge of the plates ( 20 a, 22 ), with the exception the mixing plate ( 20 b) or mixing plates, the elongated recess ( 25 ) or recesses of which extend to the secondary channel or channels of this educt, and the fluid supply ( 12 b) for this educt in the housing ( 10 ) radially to the stack ( 15 ) is arranged. 10. Micromixer according to one of claims 6 to 9, characterized in that the intermediate plate ( 22 ) and the mixing plate arranged in front of it in the flow direction ( 20 a, 20 b) are designed together as a one-piece combination plate ( 35 a, 35 b) which to form the main channel ( 23 ) and the secondary channels ( 24 ) openings ( 24 a, 24 b) and to form the elongated recesses ( 25 ) countersinks ( 36 ). 11. Micromixer according to one of claims 1 to 10, characterized characterized in that a heat exchanger is integrated in it. 12. Process for the static mixing of two or more starting materials, thereby characterized in that at least one main stream is formed from each educt is, from which at least a partial stream is branched off, and the Partial streams of all starting materials are combined in one product stream, whereby the individual educt streams alternating in shape be supplied to the product stream that fluid lamellae in Flow direction are stacked, this diffuse into each other. 13. The method according to claim 12, characterized in that the Cross-sectional geometries of the main stream, the product stream and the Partial flows are dimensioned such that the pressure drop in the main flow approximately equal to that of the product stream and small compared to that Pressure drop of the partial flows.