The present invention relates to a static mixer comprising mixing elements for separating the components to be mixed into a plurality of streams, as well as means for the layered junction of the same, including a transversal edge and guide walls that extend at an angle to said transversal edge, as well as deflecting elements arranged at an angle to the longitudinal axis and provided with openings.
A static mixer of this kind is e.g. known from U.S. Pat. No. 5,851,067. This patent in turn is a further development of U.S. Pat. No. 5,944,419. These references disclose a mixer that is divided into chambered strings; according to the first cited U.S. patent, four chambered strings are created by four alternately disposed passages and the mixer further comprises re-layering chambers. In the second cited mixer, two flanges or alternatively two pairs of flanges crossing one another are disclosed with passages disposed in such a manner that respective bottom section plates are situated above respective openings.
Although mixers of this kind achieve a better mixing of the components with reference to its length and exhibit a smaller pressure drop than conventional mixers using mixing helixes, they include relatively large dead volumes in which the composition will harden, thereby leading to an eventual plugging of the mixer.
On the background of this prior art, it is the object of the present invention to provide a static mixer achieving a high mixing efficiency with reduced dead volumes and reduced pressure drop. This object is attained by a static mixer wherein said mixing element comprises a transversal edge and a following transversal guide wall and at least two guide walls ending into a separating edge each with lateral end sections and with at least one bottom section disposed between said guide walls, thereby defining at least one opening on one side of said transversal edge and at least two openings on the other side of said transversal edge.
The invention will be explained in more detail hereinafter with reference to drawings of exemplary embodiments.
Seen in the flow direction, i.e. from the bottom of the drawing, one end of each individual mixing element 2 comprises a transversal edge 8 of a transversal guide wall 8′ that is followed by two end sections 6 and 7 extending perpendicularly thereto and including complementary lateral openings 11 and 12, and by a bottom section 9 and a complementary bottom section opening 10, the latter extending between two guide walls 4′, 5′ each of which ends in a respective separating edge 4, 5, where the guide walls are aligned in parallel with the longitudinal center axis. In the present example, the end sections extend over half the length of the separating edges. The openings, resp. their cross-sectional areas, and the length of the webs essentially determine the pressure drop between the inlet and the outlet of the mixer.
The mixing element 2′ following mixing element 2 comprises the same components and structures, but it is superimposed on first mixing element 2 in a position rotated by 180° with respect to the longitudinal axis. The following mixing elements are also identical to mixing element 2 and arranged one after another while rotated by 180° each as seen in the longitudinal direction. The flow direction is indicated by arrow 13.
During further dispensing, the six streams reach the following mixing element 2′. In the process, on one side of the transversal edge, the mixed and spread streams AG, BG, and CG are displaced through lateral openings 11 and 12, and on the other side of the lateral edge, the spread streams AG, BH, GH are displaced through bottom opening 10, as indicated in
Then, the mixed and spread streams A2.1, B2.1, and C2.1 are displaced outwards through lateral openings 11 and 12, and the mixed streams A2.2, B2.2, and C2.2 are displaced inwards through bottom opening 10, as follows from
In the next step, the displacement occurs in the other direction, i.e. streams A3.1, B3.1 and C3.1 are displaced inwards and A3.2, B3.2 and C3.2 outwards, as shown in
The arrangement and the construction of the mixing elements result in a three phase sequence of the mixing process, in which the composition is first divided, then spread and subsequently displaced, only to be divided, spread, and displaced again in the following step.
This is shown in the diagram of
In an alternative embodiment for a larger mixer, more than two separating edges and guide walls may be provided, e.g. three separating edges and guide walls, which in the case of two components divide the material into more then six streams, while the bottom walls resp. openings are arranged in alternate directions resp. mutually offset. Also, as in the preceding example, a transversal edge is provided, so that the streams are divided into two portions. The result is an analogous configuration of a mixing element comprising more than one transversal edge and more than two separating walls.
Alternatively, it is also possible to operate the mixer in the reversed direction with respect to the flow direction, so that the material first reaches the separating edges rather than the transversal edge. Thus, the composition is first divided into three parts and then, during its passage through the two openings, into two parts. In this inverse flow direction, the two outer streams unite and spread on one half of the transversal edge while the two middle streams unite and spread on the other half of the transversal edge.
In
The two end sections and the bottom section are complementarily associated with bottom section opening 10 between the guide walls and with the two lateral openings 11 and 12 on either side of the guide walls. The openings, resp. their cross-sectional areas, essentially determine the pressure drop between the inlet and the outlet of the mixer.
The mixing element 2′ following mixing element 2 comprises the same components and structures and is disposed on first mixing element 2 in a position rotated by 180° with respect to the longitudinal axis. Likewise, the following mixing elements are also arranged one after another in positions rotated by 180° each with respect to the longitudinal axis. The flow direction is indicated by arrow 13.
In
During further dispensing, the six streams reach the following mixing element 2′. In the process, the respective pairs of streams A1.G and A1.H, B1.G and B1.H, and C1.G and C1.H=A1.1 and A1.2, B1.1 and B1.2, and C1.1 and C1.2 are mixed with one another according to
In the next step, a displacement in the other direction results, i.e. stream B2.1 displaces stream B2.2, stream A2.2 displaces stream A2.1, and stream C2.2 displaces C2.1, as appears in
Here also, the arrangement and construction of the mixing elements result in a three phased sequence of the mixing process in which the composition is first divided, then displaced and finally spread, only to be divided, displaced, and spread again in the following step.
This follows from the diagram of
The mixers described above not only provide an intimate mixing of the materials but first of all a lower pressure drop as well as reduced dead volumes as compared to other mixers mentioned in the introduction.
Based on this simplified discussion of the schematic mixing operations, the following variations are possible: In these exemplary embodiments, mixers having rectangular resp. square cross-sections have been described, and the two impinging components have the same cross-sectional area. However, this need not always be the case, but any cross-sectional, resp.volume stream ratio of the two components G and H may be chosen at the inlet section, e.g. between 1:1 and 1:10, whereby the dimensions of the mixing elements remain the same. It is however possible to envisage specially adapted mixing elements. This means that the transversal edge need not be arranged on the center line of the mixing element. The same applies to the distance between the separating edges and the guide walls.
Furthermore, the separating edges and guide walls may be arranged at a mutual angle, and likewise, the end sections and the bottom section as well as the transversal edge may be arranged at a mutual angle, so that the openings are not necessarily rectangular or square. Also, the edges, e.g. the transversal edge, may incorporate a bend. The mixing elements need not be arranged one after another in positions rotated by 180°, but any angle from 0° to 360° is possible.
It is also possible to arrange the previously described mixing elements in an enclosure having a cross-section other than rectangular, e.g. in a round, an orbicular, resp. cylindrical, a conical, or an elliptic enclosure.
Whereas the previously described mixing elements provide good mixing properties, the walls arranged at an angle still include dead volumes giving rise to cured material in spite of the improved design. A further reduction of the dead volume is provided by a mixer having mixing elements with curved walls. A mixer of this kind is represented in
The individual sections are not as clearly demarcated here as in the first exemplary embodiment. In contrast to the rectangular mixing element 2, the two guide walls 17′, 18′ form a curved and continuous transition between separating edges 17 and 18 situated at one end thereof and transversal edge 21 at the other end. This curved configuration of the guide walls, resp. their transition to the transversal edge appears in
The operation of this second exemplary embodiment is the same as in the first example. In analogy to the latter, the material stream consisting of the two components G and H is divided into a total of six streams AG, BG, CG, AH, BH, and CH as it leaves the first mixing element 15.
In this example, the mixing operation is effected in analogy to the first exemplary embodiment, whereas the guide walls are no longer arranged in a sharp, rectangular disposition but run towards each other in a V-shaped configuration and have a curved shape. The mixing principle according to
It is conceivable in this exemplary embodiment that the two guide walls 17′, 18′ are provided at the transition to transversal wall 21 with an additional web 152 disposed in the longitudinal axis and transversally to the transversal wall, which would theoretically divide the material into three rather than two parts at the exit near the transversal wall, see
Also, the diagram of
In analogy to the first example, the cross-sectional, resp. volume stream ratios of the components G and H may be different from 1:1, and most importantly, the guide walls leading from the separating edges to the transversal edge may assume a multitude of geometrical shapes while the mixing elements may be reversed to the shown arrangement with regard to the flow direction. Also, the mixing principle is the same in each case, i.e. the central streams mix with each other and spread on one side of the transversal edge, and then the two outer pairs of streams spread on the respective other side of the transversal edge. Furthermore, the successive mixing elements need not necessarily be rotated by 180° each with respect to the longitudinal axis as shown in
In the exemplary embodiment of
Furthermore, it follows from
In
The exemplary embodiment of
Using the mixer according to
In analogy, when using the mixer according to
A second feature common to all mixing elements are measures for reducing the dead zones, which are particularly important in the case of straight walls and cause volume losses and local curing of the material. To this end, such dead zones are filled in. Different dead zone obturations TZV are indicated especially in
At straight walls, wall layers are formed that cause layer defects during layer formation. For the detachment of such layers, for the promotion of the longitudinal mixing action in the direction of the double guide walls, and for equalizing the concentrations, inclined webs are provided on the inside and on the outside of the guide walls.
In the mixer of
Wall layers appear not only on the guide walls but also on the inner wall of the mixer enclosure. To optimize the layer formation, longitudinal webs are provided which connect the double guide walls on the outside. The longitudinal webs need not be provided in all mixing groups. In the exemplary embodiment of
The suggested measures resp. features are preferably used jointly, but embodiments where only some of the measures are applied are conceivable too.
The flow diagram of the mixing operation is shown in
At A, the two components spread on the respective side of transversal guide wall 55. At B, the portion on the right side moves towards the center and spreads over the entire length of guide walls 50, 51 while the portion on the left side divides into two halves and forms the outer two thirds. At C, these three streams are divided transversally. At D, the left half is guided towards the center and spreads over the entire length of the guide walls while the portion on the right side is divided and the halves reach respective sides of the guide walls, whereupon a transversal edge follows again, etc.
The following claims are applicable in the simplified case where the transversal edges and guide walls do not comprise any webs as web 152, which do not change the general mixing principle of the mixing elements. Moreover, the definition of a transversal wall includes a possible duplication of the transversal edge into two parallel transversal walls as this does not change the mixing principle either.
Number | Date | Country | Kind |
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2002 2072/02 | Dec 2002 | CH | national |
This application is a continuation application of U.S. patent application Ser. No. 10/727,049, filed Dec. 4, 2003, which is abandoned.
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Number | Date | Country | |
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20060187752 A1 | Aug 2006 | US |
Number | Date | Country | |
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Parent | 10727049 | Dec 2003 | US |
Child | 11409102 | US |