Title of Invention

" A MIXER CONNECTED IN A TUBE"

Abstract

A mixer connected in a tube (10) with at least one mixing element (1,10 which comprises two axial sections (1a, 1b), werein at least one separating flange (2,2) is associated with each section and subdivides the section, the separating flanges of the two sectioins cross one another, the tube cross section is divided into subareas by the separating flanges, and open subareas as well as such covered by deflection plates (3,3) are provided at the boundary (3a,3a) between the sectioins and exactly one open subarea (4,4} is connected on both sides of each separating flange.

Full Text

The invention relates to a mixer connected in a tube and which contains at least one mixing element or one mixing body. It also refers to the use of such a mixer. A mixer is known from US-PS 3 051 453 which is composed of a linear array of mixing elements, and which is subsequently referred to as "multiflux mixing body". This multiflux mixing body, the cross section of which is square, has two channels which continually narrow in the direction of flow up to the middle of the mixing body and then continuously expand in a plane rotated by 90° after reaching the narrowest point. A medium flowing through the mixing body experiences a rearrangement in which the number of partial layers is doubled. The multiflux mixing body can from a geometrical point of view — be constructed of four wedge shaped partial bodies and two triangular plates. In a special embodiment the wedges have the form of a halved cube which is halved along the diagonal of a face. In each case two of the wedges — the one rotated by 90° with respect to the other - form a united partial body. The two plates form partition walls between the two channels of the mixing body. The partial bodies occupy a volume comprising 25 to 30 % of the tube volume associated with the mixing body. Analogous mixing bodies with four channels — so-called ISG mixing bodies (ISG = Interfacial Surface Generator) — are known (cf. H. Briinemann, G. John "Mischgiite und Druckverlust statischer Mischer mit verschiedenen Bauformen", Chemie-Ing.-Techn. 43 (1971) p. 348) . The ISG mixing bodies have circular cross sections. In a mixer with ISG mixing bodies, eight partial layers are produced in a medium consisting of two components to be mixed. The known multiflux and ISG mixing bodies require a relatively large amount of material for their construction, the volume of which takes up namely 25 to 30 % of the tube volume. The lengths of the mixing bodies in the direction of flow are relatively large, namely approximately of the same size as the tube diameter. The object of this invention is to create a mixer of the multiflux or ISG type, the mixing bodies or mixing elements of which can be constructed of less material. This object is satisfied by the features named in claim 1. The amount of the volume left empty is greater than 80 to 90 %, and hence the amount of material required substantially smaller. Thanks to its special form the mixing element of the mixer in accordance with the invention can be made substantially shorter, namely at least half as long - with an effect comparable to the known mixing bodies. A mixer with a plurality of such elements is defined in claim 2. The dependent claims 3 to 18 refer to advantageous embodiments of the mixer in accordance with the invention. Claims 19 and 20 concern applications of the mixer. Accordingly, there is provided a mixer connected in a tube with at least one mixing element which comprises two axial sections, wherein at least one separating flange is associated with each section and subdivides the section, wherein the separating flanges of the two sections cross one another, the tube cross section is divided into subareas by the separating flanges, and open subareas as well as such covered by deflection plates are provided at the boundary (3a, 3a') between the sections and exactly one open subarea is connected on both sides of each separating flange. The mixer in accordance-with the invention has mixing elements of an especially simple fornu Thanks to this form a monolithic mixing body which comprises a series of several mixing elements placed one after the other can easily be constructed by injection moulding of plastics or by precision casting (steel), and two-part tools can be used especially in the simplest embodiments (two hole versions). The mixing bodies in accordance with the invention can also be constructed in a simple manner from sheet metal for example. The mixer in accordance with the invention is especially suitable for viscous media such as plastics/ resins or glues {where the Reynolds .number Re = v-D-p/η) is less than 1; v: velocity of the flowing medium, D: tube diameter, p: density of the medium, Η: viscosity). As regards quality of mixing and pressure loss (= NeReD, Ne: Newton number) the mixer in accordance with the invention is superior to the known static mixers: two flowable media of similar viscosity can be mixed homogeneously over a distance (L) of less than ten tube diameters (D). Contrary to the known multiflux or ISG mixers, the mixer in accordance with the invention has no channels with confusor-and diffusor-like sections or bores. Experiments showed that simple plates with holes and separating flanges which are placed on the plates yield a surprisingly good quality of mixing. Effects that were to be expected due to the lack of confusor- and diffusor-like sections turned out to have practically no negative influence 'with respect to the quality of mixing. For the mixer in accordance with the invention, tubes of arbitrary cross section can be provided; square or circular cross sections are however preferable. Experiments were carried out with mixers in accordance with the invention whose mixing elements had 2, 3 and 4 holes each. The length of the elements was in all cases half the tube diameter. The experiments yielded a homogenisation (coefficient of variation s / x- ≤ 0.01 over a distance of 8, 7 and 8 tube diameters respectively. The pressure loss was much smaller than in the known multiflux and ISG mixers. The measured results are summarised in the following table. The definitions of the quantities WLV/ W1/3 and WLL1/3 are known for example from the following publication: "Mischen beim Herstellen und Verarbeiten von Kunststoffen" in the series "Kunststofftechnik", VDI-Verlag, Dusseldorf, 1991 (The definition of the coefficient of variation s / x-, see above, can also be found there). These values, which are designated as specific effects, give relative data on the volume of the mixer, its diameter and the mixer length; they refer to the known SMX mixer, which is known for exrample from the DE-PS 28 08 854 (= P.5473). The homogenisation length (L/D)h has been read for s / x- = 0.01 (cf. Fig. 9). (Table Removed) The multiflux mixer is outperformed with respect to the specific effects by the mixers tested. In the following the invention is explained in more detail on the basis of the drawings. Shown are: Fig. 1 an exploded view of a static mixer in accordance with the invention with two mixing elements (two-hole version), Figs. 2-4 variations of Fig. 1 on the mixing element, Figs. 5a,b mixing elements with two separating flanges per section (three-hole version), Fig. 6 a longitudinal section through a mixer with elements in accordance with Fig. 5, Figs. 7a,b deflection plates for mixing elements with three separating flanges (four-hole version), Fig. 8 mixing elements for a square tube and Fig. 9 a diagram with measured results for the coefficient of variation s / x- (with x- = 0.5). The mixing elements 1 and 1' of Fig. 1 arranged in a tube 10 each consist of two separating flanges 2 and 2' and two deflecting plates 3 and 3', which lie in a plane 3a, 3a' respectively indicated by the chain dotted lines. The plane 3a lies perpendicular to the tube axis 5 and parallel to planes 2a and 2b, which touch the upper edge 20 and the lower edge 21 of the separating flanges 2 respectively. The three planes 2a, 3a and 2b bound two sections la and Ib of the mixing element 1. To each section is assigned a separating flange 2 subdividing the section. The separating flanges 2 of the two sections la and Ib cross one another at right angles. The tube cross section is subdivided into four equal subareas by the separating flanges 2, where two of these subareas are covered by the deflecting plates 3. The open subareas are provided as constrictions and passage holes 4 for the medium to be mixed. The two successive mixing elements 1 and 1' are substantially built up in the same way. However, mixing element 1 represents the mirror image of mixing element 1'. The neighbouring separating flanges 2 and 2' cross one another; the open subareas 4.and 4' are arranged mutually offset. The deflecting plates 3 can also subtend an angle a with the cross sectional plane 3a — see Fig. 2. This angle a is advantageously chosen to be not greater than 30°. Figures 3 and 4 show further embodiments with inclined surfaces. If the axis 5 is understood to be vertical, the arrow 6 in Figures 2 to 4 represents the fall line of a deflecting plate 3. In Fig. 2 this arrow 6 is parallel to the upper separating flange 2. In the exemplary embodiment of Fig. 3 the arrow 6 is tangential to a circular cylinder concentric with the axis 5. In the exemplary embodiment of Fig. 4 the arrow 6 is directed radially outwards. Figures 5a and 5b show mixing elements 1 and 1' in each of which two separating flanges 2 are associated with a section la and Ib respectively (not shown in these figures). On both sides of each separating flange 2 is placed exactly one open subarea 4. The mixing element 1' with the open subareas 4' represents an immediately neighbouring element of the mixing element 1. The open subareas 4 and 4' are arranged mutually offset. In the three hole version (Fig. 5} the forms of the two mixing elements 1 and 1' are identical and not mirror imaged as in the two hole version (Fig. 1). For the manufacture of the three hole mixing body by the process of injection moulding the elements can be divided into two halves. The boundaries between the half elements are shown in the Figures 5a and 5b as chain dotted lines 7 and 7' respectively. Monolithic partial bodies each containing a series of such half elements can be constructed simply using two part tools. The entire mixing body is obtained by joining together two monolithic partial bodies. The longitudinal section of Fig. 6 shows the individual mixing elements 1 and 1' following close upon one another. Spacings between individual neighbouring elements or between all elements can however also be provided. Mixing elements built in with spacing can be connected by connecting pieces to form a monolithic mixer. In Fig. 6 the course of the flow of the medium to be mixed is. also indicated by the arrows 8, 8' and 8". Arrow 8' is perpendicular to the plane of the diagram and is directed forwards; arrow 8" — also normal — is directed towards the rear. The reference symbol 9 points toward a position at which the arrows indicate the creation of two partial streams. It is advantageous for the deflection plates 3 to lie in a common plane. In the presence of at least two separating flanges 2 per section (three hole version) several deflection plates 3 can form a common plate or a single plate 30 (four hole version): see Figures 5a and 5b and the corresponding Figures 7a and 7b for the four hole version. In each of the Figures 7a and 7b only the single and common deflection plate 30 or 30' is shown. The chain dotted lines 23 represent the lower edges of the upper separating flanges. As in the previous two hole version the forms of neighbouring mixing elements are mirror images of one another. In place of a circular cross section, the mixer in accordance with the invention can have a cross section of any other form, for example that of a square. The angles of crossing between the separating flanges 2, 2' can also deviate from 90°. The sections la and Ib can be of different lengths. It is advantageous for the length of the sections la and Ib to be in the range from D/8 to D; it should preferably be D/4. Fig. 8 illustrates what deviations from the simple form described above are conceivable: connecting elements 35 are placed between the spaced mixing elements 1, 1'. The separating flanges 2 have additional elements 25 as strengtheners or stream deflectors. Separating flange's 2' and 2" of neighbouring mixing elements 1' and I" are fitted together at the position 29. Some of the separating flanges 2 and deflection plates 3 are non planar. The mixing elements 1 and 1' have different numbers of separating flanges 2 and 2' per section la and Ib respectively, namely two and one respectively. One separating flange 2 has a recess 29. Fig. 8 is merely to be understood as illustrating individual features; this particular combination of all features listed in a single mixer need not be advantageous. The tube 10 can also be shaped cohically (not shown) so that it tapers in the direction of flow; the mixing bodies 1, 1' must in this case be constructed in differing sizes corresponding to the varying cross section. The diagram in Fig. 9 shows the dependence of the coefficient of variation s / x- on L/D for x- = 0.5 in accordance with the above mentioned experiments. x- = 0.5 means that the proportions of the components to be mixed are equally large. The reference symbols 1* to 5* refer to the mixer types that are listed in the above table. The mixer in accordance with the invention, which can be constructed monolithically of little material, can advantageously be constructed of an economical, combustible plastic by injection moulding. This mixer is especially suitable for use as a one-way article. The mixer in accordance with the invention can also be used to mix turbulently flowing media. WE CLAIM:- 1. A mixer connected in a tube (10) with at least one mixing element (1,1') which comprises two axial sections (la, Ib), wherein at least one separating flange (2,2') is associated with each section and subdivides the section, the separating flanges of the two sections cross one another, the tube cross section is divided into subareas by the separating flanges, and open subareas as well as such covered by deflection plates (3,8') are provided at the boundary (3a, 3a') between the sections and exactly one open subarea (4,4') is connected on both sides of each separating flange. 2. Mixer as claimed in claim 1, wlterein a plurality of mixing elements (1, 1') is present; and in that with respect to successive mixing elements on the one hand neighbouring separating flanges (2,2') cross one another and on the other hand the open subareas (4,4') are connected so as to be offset with respect to one another. 3. Mixer as claimed in claim 1 or 2, wherein the tube cross section is subdivided by the separating flanges (2, 2') into subareas of at least the same size. 4. Mixer as claimed in any one of claims 1 to 3, wherein the separating flanges (2) of neighbouring sections (la, Ib) cross one another at an angle of 90°. 5. Mixer as claimed in any one of claims 1 to 4, wherein both sections (la, 1b) of a mixing element (1) are at least of the same size. 6. Mixer as claimed in any one of claims 1 to 5, wherein the length of one of the mixing elements (1) is smaller than the largest tube diameter, preferably smaller than half of the largest tube diameter. 7. Mixer as claimed in any one of claims 1 to 6, wherein the deflection plates (3) lie in a common plane; and in that in the presence of at least two separating flanges (2) per section (la, Ib) several deflection plates form a common plate or all deflection plates from a single plate (30). 8. Mixer as claimed in any one of claims 1 to 7, wherein the deflection plates (3) are inclined with respect to the corss-sectional plane (3a); and in that angle (a) between deflection plate and cross-sectional plane is less than 30°. 9. Mixer as claimed in any one of claims 1 to 8, wherein several successive mixing elements (1, 1') are present in the form of a monolithic structure, especially one produced by injection moulding. 10. Mixer as claimed in any one of claims 1 to 9, wherein a spacing is provided between at least two neighbouring mixing elements (1, 1'). 11. Mixer as claimed in claim 10, wherein the connection elements (35) are connected between separated mixing elements (1,1')• 12. Mixer as claimed in any one of claims 1 to 11, wherein the tube (10) has a square or circular cross section. 13. Mixer as claimed in any one of claims 1 to 12, wherein at least individual separating flanges (2, 2') and/or deflection plates (3, 3') have additional elements (25) for strengthening or guiding the flow. 14. Mixer as claimed in any one of claims 1 to 13, wherein the separating flanges (2, 2') of neighbouring mixing elements (1, 1') are inserted (29) into one another. 15. Mixer as claimed in any one of claims 1 to 14, wherein at least individual separating flanges (1, 2') and/or deflection plates (3, 3') have additional recesses (26). I 16. Mixer as claimed in any one of claims 1 to 15, wherein the tube (10) is constructed to be conial and tapering in the direction of flow and the mixing bodies (1,1') are constructed in different sizes corresponding to the changing cross section. 17. Mixer as claimed in any one of slakns 1 to 15, wherein at least two mixing elements (1, 1') have different numbers of separating flanges (2, 2') per section (la, 1b)). 18. A mixer connected in a tube substantially as herein described with reference to the foregoing examples and accompanying drawings.

Documents:

909-DEL-1996-Abstract.pdf

909-DEL-1996-Claims.pdf

909-del-1996-complete specification (granted).pdf

909-del-1996-correspondence-others.pdf

909-del-1996-correspondence-po.pdf

909-DEL-1996-Description (Complete).pdf

909-DEL-1996-Drawings.pdf

909-del-1996-form-1.pdf

909-del-1996-form-13.pdf

909-del-1996-form-2.pdf

909-del-1996-form-3.pdf

909-del-1996-form-4.pdf

909-del-1996-gpa.pdf

909-del-1996-petitionothers.pdf