WO2024221118A1 - Static mixing elements with a separator and deflecting surfaces and static mixers - Google Patents

Abstract

The invention relates to static mixing elements with a separator (2), preferably in a tube (1) with two blade-like deflecting surfaces (4, 5) adjoining same which, in the axial projection, completely cover a sector of the cross-section and delimit two axial sections (I, II) and two windows (8, 9) for the axial passage of the flow. The deflecting surfaces have raised edges (6,7). The fact that the deflection surfaces are simultaneously inclined towards the separator and raised from the cross-sectional plane and the axial projection of the deflecting surfaces covers a sector of over 56% of the cross-section makes it possible to significantly improve the mixing quality compared to known structures, in particular with a circular cross-section.

Description

Static mixing elements with a separating web and deflection surfaces and static mixers

technical field

The invention relates to static mixing elements and static mixers in a flow channel, preferably in a circular pipe with at least one separating web per mixing element, deflection surfaces and windows for axial flow. Such static mixers are preferably used in the laminar flow range for highly viscous media. Typical applications are disposable mixers for hardening resins, adhesives or static mixers for plastic melts in plastic processing with injection molding machines or by means of extrusion.

State of the art

To date, many static mixers are known and in use in which the flow is divided into partial flows by dividers or channels and deflected by deflection surfaces. A static mixer is formed by several such mixing elements which are arranged linearly one behind the other in a pipe or flow channel in the direction of flow. In many known static mixers, the flow is divided into 2 partial flows, twisted or rearranged, compressed and expanded again. The mixing process is similar to the process in a calender (calender model). According to an idealized concept, with laminar flow, layers are formed in each mixing element and the number of layers doubles from mixing element to mixing element. In practice, the actual number of layers achieved or their thickness after a larger number of mixing elements often deviates by orders of magnitude from this ideal. The oldest static mixers with this mixing principle were the Multiflux (US 3051453) and the Wendei mixer (US 3286992). The reversible mixer is still widely used today for so-called disposable mixers for reactive resins and adhesives, because it also allows entire mixer rods made of many such mixing elements to be produced in one piece using simple, two-part plastic injection molding tools. can be manufactured cost-effectively in large quantities. The mixing elements of the reversible mixer only take up a small proportion of the mixer volume and therefore it has a low pressure loss. The length of a mixing element is typically 1.5 pipe diameters D and the mixer length required for homogenization is typically 30D (D = pipe diameter). In contrast, the mixing elements of the Multiflux mixer take up to 30% of the mixer volume and therefore it has a much greater pressure loss. The mixer length required for homogenization is, however, much shorter than with the reversible mixer and is typically 10D. Both mixers divide the flow into 2 channels or partial flows and bring them together again to divide them again. The reversible mixer has a circular cross-section of the flow channel, while the Multiflux mixer in its original form was preferably used with a square cross-section of the flow channel because this achieved a better mixing result. However, there are also known versions of this mixer with a circular cross-section of the flow channel, which can also be manufactured with a two-part plastic tool.

Today, the mixers according to EP 0749776A1 or EP 0815929A1 are static mixers with the same mixing principle as the Multiflux mixer, but with a simpler and improved shape, for example for use as disposable mixers. Here, too, entire mixer rods can be manufactured using simple, two-part tools made of plastic injection molding. The length of a mixing element according to these inventions is only approx. 0.5 D and the mixing elements take up a volume of less than 10% of the volume assigned to the mixer. This results in a low pressure loss and a very short homogenization length of approx. 8D. Today, a large number of similar, derived or related mixer structures are known, for example according to US 3239197,

EP 1 149 626A1, WQ2017/027275A2, EP 1 125 626A1, EP 2 599 540, or EP 3 338 882A1.

The relative standard deviation s/x from a concentration measurement across the cross-section is often used as a measure of mixing quality for a mixture in a static mixer. Here, s is the measured standard deviation and x is the measured mean value of the concentration in a cross-section. This relative standard deviation is also known as the coefficient of variation COV. The conductivity method [Chem. -Ing.- Tech.52(1980) 4, pp.285-291] is often used to measure concentration. Two viscous partial flows with different electrical conductivities are pressed through the static mixer and mixed. To measure conductivity or concentration, a measuring probe is pulled across the outlet cross-section. A newer, experimental measuring method is the LIF (Laser Induced Fluorescence) method [The Canadian Journal of Chemical Engineering, Volume 76, June 1998]. To measure concentration, a fluorescent tracer is used which is induced by a laser beam. With this measuring method, the flow is not influenced by a measuring probe. Finally, numerical flow simulation (CFD) does not require any experiments at all. The COV depends on the measurement method and the sample size. In numerical flow simulation, the result can also be strongly influenced by the model used and numerical influences. A mixture with a COV=1% is considered homogeneous. The corresponding mixer length is called the homogenization length.

The formation of layers in laminar flow can also be demonstrated very easily and precisely by pressing two highly viscous resin components with different pigment colors, mixed with hardener and hardening in a short time, through a mixer. The hardened mixer rod is then cut open after each mixing element. This freezes the mixing process or the mixing state in a cross-section forever without being influenced by diffusion or other influences and can be easily analyzed. The only disadvantage is that the mixer being examined is lost or "frozen". Today, prototypes of mixers can be easily and inexpensively produced from plastic using 3D printing. This has made this old method of investigation very interesting again. A simple evaluation is to count the layers formed or, even simpler and more reliable, to measure the maximum layer thickness I in a cross-section. If you compare the measurements of the max. layer thickness I with the conductivity method, for example, it can be seen that the homogenization length (COV = 1%) with a layer thickness of approx. 25 pm is reached. Since this layer thickness is hardly measurable any more, it is determined by exponential extrapolation. The mixing effect of the known static mixers in the laminar range is sometimes very good and, although not ideal, follows an exponential layer formation law. Many static mixers with a circular pipe cross-section have one problem in common that has not yet been solved. The layer thicknesses across the cross-section and beneath the layers can vary greatly, or the layers do not extend across the entire cross-section. In mixers similar to the Multiflux mixer or EP 0749776A1 with a round pipe cross-section, there is a significant deviation in the thickness of the layers in the edge areas compared to the layers in an inner area. With a square cross-section of the flow channel, this effect is less pronounced. For this reason, for example, disposable mixers with these or similar mixer geometries such as those according to EP 0749776 are usually offered with square housings, although a circular pipe would be preferred as a housing. For many applications, a square housing is not an option and other static mixers are preferred. One example of this is static-dynamic mixing systems in which a mixer spiral is additionally set in rotation by a drive.

Fig. 1 shows the distribution of the layers and layer thicknesses that were determined from the cross-sections during tests with a static mixer according to EP 0749776 with a square cross-section. The images were traced from the photographic evaluation of the cross-sections. Image a) shows the state at the inlet (mixture 1:1, black/white), image b) the state at the outlet of the first element and image c) the state at the outlet of the second element. It is clearly visible that the number of layers formed corresponds very well to expectations according to the calender model, but also that the layer thicknesses are not uniform even with the square flow cross-section and that the edge layers are significantly larger than expected. This deviation is maintained across all other mixing elements, although the thickness of the layers decreases steadily and exponentially with increasing mixer length. The mixing quality in the form of a decreasing maximum layer thickness I is significantly lower than expected with an ideal mixing law. Fig. 7, trend line 2 shows the course the measured maximum relative layer thickness l/l ₀ for this mixer shown as a function of the relative mixer length L/D. Trend line 3 shows the course of the relative layer thickness over the relative mixer length according to the same measurements for a spiral mixer with a circular flow cross-section. The layer thickness is already an order of magnitude higher than in line 2 after just a few pipe diameters. In the European patent application

EP 3907461 A1 describes a possible solution for further improving layer formation in the mixer according to EP 0749776 by enlarging the deflection surfaces beyond the separating web on the inlet side in a suitable shape and direction and thus reducing the window areas. This makes it possible to achieve a somewhat more even distribution of the layer thicknesses. This solution was developed primarily for applications as a mixer heat exchanger, also to improve the heat transfer to the pipes at the same time. However, it was found that when this solution is used for disposable mixers or for other static mixing tasks without heat transfer, the pressure loss is increased more than desired. All of the static mixers mentioned above, with the exception of the reversible mixers, also have unfavorable residence time behavior because there are zones with very different axial flow velocities or even stagnant zones. Such zones harden prematurely when processing resins with a short pot life and mean that the mixers have to be replaced more often. So far, no satisfactory solution has been found for the problem of non-uniform distribution of the layer thickness or thicker layers at the edge, especially in disposable mixers with a circular flow channel.

Description of the Invention

The object of the present invention is to find a static mixer or disposable mixer with low pressure loss that achieves a much more uniform distribution of the layer thicknesses over the cross-section and thus a shorter homogenization length than the known static (disposable) mixers, especially with a circular pipe as the mixer housing with low pressure loss and that can be easily manufactured with a two-part open/close (O/C) tool and as a whole mixer rod as a monolithic part. In addition, an improvement in the residence time distribution and a reduction in the stagnant zones should be achieved.

The object is solved by the features of patent claim 1. The further independent and dependent patent claims describe particularly advantageous embodiments or applications of the invention.

The term "blade-like deflection surfaces" includes both completely flat and curved deflection surfaces, for example concave and/or convex curved deflection surfaces.

Short description of the drawings

The invention is explained below with reference to drawings.

Fig. 1 Representation of the layer thicknesses after measurement with hardening resins in a mixer according to EP 0749776 with a square cross-section. The image was traced from the photographic evaluation. a) Mixer inlet, b) Outlet from mixing element 1, c) Outlet from mixing element 2

Fig. 2 Perspective view of a pipe 1 with a static mixing element according to the invention with the length H with 2 blade-like deflection surfaces 4,5 with edges 6,7 on the inlet side (section I) and a separating web 2 with the width D and the height h in an axial plane through the pipe axis 3 on the outlet side (section II). Cross-sectional planes E1 (mixing element inlet), E2 (intermediate plane at the transition from deflection surfaces to the separating web) and E3 (mixing element outlet). The arrows indicate the cross-flow directions in the individual sections. The preferred axial flow direction is shown by the large arrow in the pipe axis.

Fig. 3 Axial section (plane EB, Fig.4) through the pipe axis and perpendicular to the separating web 2 of a mixing element according to the invention with inclined deflection surfaces and a flow area F that is larger than the value Dxh without inclination. The sections are not hatched for better understanding. The direction arrows show the cross-flow directions in sections I and II.

Fig. 4 View from the inlet side of a mixing element type A according to the invention with a separating web 2 in an axial plane EA and deflection surfaces 4 and 5 and windows 8 and 9 in a pipe 1. In this example, the edges 6,7 on the inlet side form a common, straight web through the pipe axis which is at an angle ß to the separating web 2.

Fig. 5 View from the inlet side of a mixing element type B according to the invention, which is constructed as a mirror image of the element type A with deflection surfaces 4' and 5' offset from the separating web 2 or 2' and windows 8' and 9'. The separating webs 2, 2' of successive mixing elements type A and type B are preferably parallel to one another in a common axial plane EA in the middle of the pipe. The inlet edges of the edges are preferably bevelled.

Fig. 6 Representation of the distribution and thickness of the layers formed after tests with hardening resins at the outlet of the second mixing element for a mixer according to the invention in a circular pipe. The image was traced from the photographic evaluation. Fig. 7 Course of the measured maximum layer thickness I in comparison to the initial thickness Io as a function of the relative mixer length L/D for the mixer according to the invention (1) with a circular cross-section, a mixer according to EP 0749776 with a square cross-section (2) and a spiral mixer (3) as exponential trend lines.

Fig. 8 Longitudinal section across the separating web (plane EB) through a complete mixer rod made of mixing elements type A and type B with lateral connecting elements 10,11 in a flow channel 1.

Fig. 9 View from the inlet side of the mixer rod according to Fig. 8 with lateral connecting elements 10,11 which adapt to the pipe cross-section and which can be manufactured as a disposable mixer with a simple, two-part tool made of plastic injection molding. The opening direction of the tool divided in the plane EB is indicated by the arrows C/O.

Fig. 10 Longitudinal section (plane EB) through a mixing element according to the invention with ring 12 for reinforcement, which can be produced as a particularly strong, monolithic mixing element, e.g. as a precision cast part or in 3D printing, and is inserted into a tube with diameter D. Individual mixing elements with ring can also be made from plastic or wax with a simple, two-part tool.

Fig. 11 View from the inlet side of a mixing element according to the invention with ring 12 according to Fig. 10

Fig. 12 Longitudinal section through a mixing element according to the invention with convexly curved deflection surfaces

Fig. 13 Longitudinal section through a mixing element according to the invention with concavely curved deflection surfaces Fig. 14 View from the inlet side of a mixing element according to the invention in which the edges of the deflection surfaces form a curved line

Fig. 15 View from the inlet side of a mixing element according to the invention with a square flow cross-section.

implementation examples

The static mixer according to the invention, preferably in a pipe 1, consists of mixing elements, each with a separating web 2 of height h in a plane through the pipe axis 3, parallel to the axial flow direction and running over the entire cross-section, and on the separating web 2 there are two blade-like deflection surfaces 4, 5 with edges 6, 7 which completely cover a sector of the cross-sectional area in the axial projection and two windows 8, 9 for the axial passage of the flow. It is particularly advantageous if the covered sector is 56% - 67% of the radial cross-sectional area. If the edges 6, 7 on the inlet side form a straight web across the cross-section, this corresponds to an angle ß = 100 -120°. With a greater coverage, the pressure loss increases and a reversal occurs such that the layers near the separating web become larger than at the edge. The deflection surfaces separate two axial sections I and II. Section I is the area upstream from the deflection surfaces to the inlet plane E1. The inlet plane E1 is perpendicular to the pipe axis 3 and touches the upper edge of a mixing element. Section II is the area downstream from the deflection surfaces to the outlet plane E3. The outlet plane E3 is parallel to the inlet plane E1 and also perpendicular to the pipe axis 3 and touches the lower edge of a mixing element or the separating web 2. In section I, the flow is shifted, divided and compressed in opposite directions into the windows 8,9, perpendicular to the axial flow direction, and the partial flows reach opposite sides of the separating web 2 in section II. Here the flow is expanded again to the full cross-section. In the outlet plane E3, the partial flows are brought together again to be divided again in the next mixing element. The edges 6,7 hold the flow on the deflection surfaces 4 and 5 respectively and prevent it from entering the adjacent window on the same side of the separating web 2. The The lateral edges of the deflection surfaces meet at the pipe axis and form a straight or curved surface which also runs across the entire cross-section and protrudes over the deflection surface against the direction of flow. The edges preferably run parallel to the direction of flow, at least at the inlet. However, they can also be inclined towards it. The height of the edge above the deflection surface can vary across the diameter. Preferably, however, the edges are raised up to the inlet plane E1 of a mixing element and also form a straight or curved web surface on the inlet side, or the edges 6 and 7 together form a straight web which runs across the entire cross-section. The deflection surfaces 4,5 lie in planes transverse to the pipe axis, but are raised from the cross-sectional plane E2 and against the direction of flow. The cross-sectional plane E2 runs perpendicular to the pipe axis, parallel to the planes E1 and E3 and through the upper edge of the separating web 2. As a result of the deflection surfaces being raised, the area F (Fig.3) under the deflection surfaces in section II and perpendicular to the separating web 2 in section II is increased by 25 - 50%. If the deflection surfaces are flat and straight, this would correspond to an angle of inclination of a = 15 - 30° to the cross-sectional plane E2. The inclination on both sides of the separating web 2 should be opposite and against the respective window. The area F, downstream of the deflection surfaces 4,5 and extending to the outlet plane E3, forms the passage area in a mixing element for the cross flow along the separating web 2. It is perpendicular to the separating web 2 in the plane EB through the pipe axis. The arrows in Fig. 2 and 3 indicate the transverse flow directions in the individual sections. The preferred axial flow direction is from section I to section II (large arrow in Fig. 2) or from level E1 to level E2.

In mixing tests with hardening resins with such mixing elements in which only the deflection surfaces were inclined by an angle a but not enlarged (ß = 90°), a surprising increase in the layer thickness at the edge was found compared to deflection surfaces in the cross-sectional plane. This applies to both the square and the circular cross-section. If, on the other hand, with deflection surfaces in the cross-sectional plane (a = 0°), only the coverage by the deflection surfaces is enlarged or the angle ß > 90° is selected, somewhat more uniform layer thicknesses. However, this measure is much more effective if the deflection surfaces are raised from the cross-sectional plane at the same time. The distribution of the layer thicknesses is most even when the two measures are skillfully combined.

The enlarged deflection surfaces reduce the narrowest cross-section in the windows in the axial projection. This would increase the pressure loss in the mixing elements if the deflection surfaces were located in the cross-sectional area E2 and zones with very different flow velocities or even stagnant zones would be formed. The additional inclination or elevation of the deflection surfaces to the cross-sectional plane increases the flow cross-section for the spread in the direction of the separating web in section II. This reduces the pressure loss and at the same time improves the velocity distribution or the residence time distribution. Both the deflection surfaces and their edges can have a curved, arched or spiral shape instead of a flat one (Fig. 12, 13 and 14). To further improve the residence time distribution, the transitions from the webs or edges to the deflection surfaces can have large curves. If the mixing elements are connected with connecting elements or with an outer ring, the deflection surfaces or the edges and webs at the transitions to these elements can also be wedge-shaped or reinforced with large curves in order to reduce dead zones and increase strength.

There is no upper limit for the height h of the separating web 2 or for the length H of a mixing element. The pressure loss decreases with increasing length h of the separating webs or H of the mixing elements. If, on the other hand, the length is shortened, the empty volume decreases and the pressure loss increases, but the mixing quality (layer thickness) in relation to 1 mixing element remains approximately the same. Thus, the mixing quality increases per length. It has been shown that an optimal result of mixing quality and pressure loss is achieved in most cases when h=0.2 - 0.35 D and H=0.4 - 0.7 D are selected. The mixing elements normally have an empty volume of > 90%. A static mixer is formed by a sequence of mixing elements according to the invention, type A (Fig.4) and type B (Fig.5), arranged one behind the other in the direction of flow until the desired mixing state is achieved. The elements type A and type B are identical except for the mirror-image arrangement of the deflection surfaces, ie the windows 8 and 9 of type A and the windows 8' and 9' of type B are on opposite sides of the separating web 2 or 2'. The deflection surfaces 4 and 4' or 5 and 5' are inclined in the opposite direction to the separating web 2 or 2'. The separating webs 2 or 2' of successive mixing elements are preferably located in a common axial plane EA through the middle of the pipe. This means that the windows and deflection surfaces of successive mixing elements cover one another. Mixing elements arranged one behind the other are preferably installed without gaps for a compact design. However, they can also be installed with gaps.

With the help of the described experiments with hardening resins and the cross-sectional images, the beneficial effect of this invention idea was clearly demonstrated.

Fig. 6 shows the distribution of the layers formed and their thickness at the outlet of the second mixing element in an inventive design of the mixing elements for a circular pipe. The image was also traced based on the photographic evaluation of the sectional images. The distribution of the layer thicknesses over the cross-section is already much more even here than in Fig. 1c. The trend continues in the other mixing elements according to the exponential decrease in the layer thicknesses. Fig. 7 shows the course of the measured maximum layer thickness I in comparison to the initial thickness l ₀ as a function of the relative mixer length L/D for the inventive mixer with a circular cross-section (1) and the mixer according to EP 0749776 with a square cross-section (2) as well as for a spiral mixer (3), also with a circular cross-section, as exponential trend lines. A major advance is that with the inventive mixer, even in a circular pipe, the rel. Layer thickness l/lo of the known mixer according to EP 0749776 with square cross-section is halved after only 6 pipe diameters. The difference becomes larger the longer the mixing section as a result of the exponential decrease in layer thickness. The result is a significantly shorter homogenization length of only approx. 6D. Thanks to the possibility of using normal pipes as housings The mixers are much cheaper to produce and easier to handle.

Because the deflection surfaces cover at least 56% of the cross-sectional area in the projection, the formation of mix-resistant strands that are only slightly deflected by the separating web 2 is avoided at the same time, because they are better intercepted by the deflection surfaces.

Description of manufacturing and implementation examples

Individual mixing elements as shown in Fig. 2 can be easily manufactured from 2 sheets cut out (laser, water jet) or punched. The sheets are bent to the desired shape and the 2 halves are joined together using a conventional method such as welding, gluing, soldering, riveting, screwing, etc. Of course, the mixing elements can also be assembled from more than two individual parts. The mixing elements are then inserted into a pipe individually or connected to entire mixer rods using connecting elements. The connecting elements also ensure that the mixing elements are correctly aligned one behind the other. The connecting elements also serve to absorb the axial forces that occur due to the pressure drop. Supports or retaining rings are used to axially position the mixer in the pipe, or the mixing elements are at least partially connected to the pipe, e.g. by welding. Individual mixing elements or entire mixer rods made of plastic or metal can also be manufactured using a 3D printing process.

Whole mixer rods as disposable mixers made of a large number of individual elements type A and type B are manufactured in one piece using a plastic injection molding process or from metal using a precision casting process (Fig. 8 and 9). The mixer parts are connected to one another by external, axial elements 10, 11 in such a way that the entire part can be manufactured with a simple, two-part open/close tool (O/C) and the external shape is adapted to the circular pipe cross-section (Fig. 8 and 9). This embodiment is particularly advantageous as a disposable mixer compared to the previously known disposable mixers with the impractical, square housing cross-section.

If the mixing elements require a particularly high level of strength, e.g. when used as a mixer for plastic melts during extrusion or when injection molding plastic parts, the individual mixing elements are firmly connected to an outer ring 12 (Fig. 10 and 11) to absorb the pressure forces or are manufactured as precision cast parts (lost wax process) or in 3D printing from one part. Mirror-image elements type A and type B are then installed one behind the other in the housing in the direction of flow and form the static mixer. Special cams and grooves or pins and holes are used to correctly position the mixing elements one behind the other.

Claims

patent claims 1 . Static mixing elements in a flow channel, preferably in a pipe (1 ) with the diameter (D), - the mixing elements each have a separating web (2) with a height (h), preferably in a plane EA through the pipe axis (3) parallel to the axial flow direction and running over the entire diameter - with two blade-like deflection surfaces (4, 5) in planes transverse to the pipe axis which completely cover a sector of the cross-section in the axial projection and delimit two axial sections - and two windows (8, 9) for the axial passage of the flow from a first axial section (I) on the inlet side to opposite sides of the separating web (2) into a second axial section (II) on the outlet side - wherein the deflection surfaces (4, 5) on the inlet side have raised edges (6, 7) as a lateral boundary to the windows, which meet in the pipe axis and protrude against the flow direction over the deflection surface, characterized in that - the deflection surfaces or their axial projection completely cover an area of at least 56% of the pipe cross-section and the deflection surfaces are mutually inclined towards the central web and the cross-sectional plane and/or raised from the cross-sectional plane, - such that the area (F) downstream of the deflection surfaces (4,5) and up to the outlet plane (E3) in the axial plane (EB), perpendicular to the separating web (2) and through the pipe axis (3) is increased by at least 25% compared to the value without inclination and/or elevation. 2. Static mixing elements according to claim 1, characterized in that the edges (6,7) form a common, straight web on the inlet side in the first axial section (I) which encloses an angle ß > 100° and ß < 120° with the separating web (2). 3. Static mixing elements according to claim 1 or 2, characterized in that the deflection surfaces (4,5) are flat surfaces which are inclined against the flow direction by an angle a > 15° to the cross-sectional plane and mutually towards the separating web (2). 4. Static mixing elements according to one of the preceding claims, characterized in that the height (h) of the separating web is 0.2 - 0.35D and the total height (H) of a mixing element is 0.4 - 0.7D. 5. Static mixer in a flow channel comprising at least two mixing elements arranged one behind the other in the flow direction according to one of the preceding claims, characterized in that successive mixing elements are mirror images of each other and windows and deflection surfaces of successive mixing elements cover each other. 6. Static mixer in a flow channel comprising at least two mixing elements arranged one behind the other in the flow direction according to one of claims 1 - 4, characterized in that successive mixing elements are mirror images and windows and deflection surfaces cover each other, wherein the mixing elements are preferably connected to one another by axial connecting elements which are adapted to a circular tube, in such a way that the entire static mixer can be produced by a simple open/close tool. 7. Static mixer, in particular with high strength, in a flow channel made of mixing elements arranged one behind the other in the flow direction according to one of claims 1 - 4, characterized in that the individual mixing elements are firmly connected to an outer ring for reinforcement or form a monolithic part. 8. Static mixing elements and static mixers according to one of the preceding claims, characterized in that the deflection surface is at least partially wedge-shaped and/or thickened by large radii in the transition area to the pipe wall, ring, separating webs, edges or connecting elements. 9. Application of static mixing elements or static mixers according to one of the preceding claims in a circular pipe serving as a flow channel in the processing of plastic melts. 10. Application of static mixing elements or static mixers according to one of the preceding claims as disposable mixers in a circular tube serving as a flow channel in the processing of hardening resins. 11.Static-dynamic mixer according to claim 6, characterized in that the mixer rod is connected to a drive that can set the mixer rod in rotation.