US 3051452 A
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PROCESS AND APPARATUS FOR MIXING Filed Nov. 17, 1958 44 4o L- INVENTOR.
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3 TTO NEY United States Patent 3,051,452 PROCESS AND APPARATUS FOR MIXING Leendert Nobel, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N.C., a corporation of Delaware Filed Nov. 17, 1958, Ser. No. 774,305 Claims priority, application Netherlands Nov. 29, 1957 7 Claims. (Cl. 2594) This invention relates in general to the mixing of flowing streams of gaseous, liquid and/or granular media through the use of stationary bafiles or pipe restrictors providing a tortuous flow path and more particularly to a process and apparatus for combining materials to be homogenized into a main stream and for displacing portions of this main stream relative one to the other in a specific manner.
It is generally known in the mixing art to divide a main stream of material to be homogenized into two concentric partial streams or sectors, to displace these concentric sectors relatively through the use of helically shaped stationary baffies, and to recombine the displaced sectors, after which the operation may be repeated if necessary or desired. For example, see French Patent No. 735,033.
In another known system, a main stream of rectangular cross-section is divided into a plurality of sectors, also of rectangular cross-sections, after which the individual sectors are shifted one relative to the other and reunited into the original rectangular cross-section without change in the dimensions thereof. This system is shown in German Patent No. 358,018.
The two systems described above are quite similar in operation to the shifting of pieces on a chessboard, wherein any arrangement may be obtained either by interchanging two of the pieces, or by a complete series of interchanges, but neither of Which includes exchanging portions of adjacent pieces. By proper selection of the flow rate in the operation of these systems, a high turbulence may be produced within the baffles, Which turbulence contributes substantially to the mixing or homogenizing action.
The processes described above, however, have many disadvantages and do not operate satisfactorily in certain applications. For example, although mixing does occur to some extent between adjacent sectors, and the reunited stream therefore may not be of uniform consistency. Moreover, the required or proper flow rate mentioned supra increases directly in proportion to the viscosity of material to be mixed. Consequently, it is often impossible to convey highly viscous material through the baffles at a rate necessary to produce the desired turbulence. Furthermore, even if the high flow rate Were possible, the same would lead to excessive strains or forces on the somewhat delicate baffle plates and thereby prohibit use for homogenizing highly viscous material.
One of the objects of this invention, therefore, is to provide a mixing process and apparatus not having the disadvantages of known systems.
Another object of the present invention is to provide a mixing process and apparatus not dependent upon turbulence for satisfactory operation.
Still another object of this invention is to provide a mixing process and apparatus not dependent for satisfactory operation upon excessive or extremely high flow rates.
A further object of the present invention is to provide a process and apparatus for thoroughly homogenizing a flowing stream of two or more materials regardless of the viscosity.
An additional object of this invention is to provide a stationary mixing apparatus for homogenizing a flowing "ice stream of two or more materials which may be economically manufactured and easily maintained.
In accordance with the present invention, two or more flowing streams of materials are combined into a main stream, after which the main stream is divided into a plurality of sectors having a first shape in cross-section. Thereafter, the individual sectors are shifted relative to one another simultaneously with an alteration in crosssection to a second shape overlapping two or more of the original sectors, and temporarily recombined. Subsequently, the temporary main stream is again divided into sectors which may correspond in shape to, but which consists of portions of material obtained from two or more of, the first-mentioned sectors. It can be seen, therefore, that each subsequent sector formed by division of the main stream will contain material from at least two previous sectors intermixed in a preceding operation. The procedure may be repeated, if necessary, until thorough mixing has been obtained.
Whereas in the known systems described hereinabove only the first displacement of sectors changes the overall pattern with respect to the main stream, and subsequent shifting only intensifies the mixing of material in each individual sector, each exchange of material between adjacent sectors in accordance with this invention contributes directly to mixing of the entire main stream. The reason for this is that each sector formed after a division of the main stream will contain a small quantity of material from at least two of the preceding sectors. As the mixing operation continues, a sector will receive progressively smaller quantities from each of a progressively larger number of previous sectors. In the last analysis, theoretically at least, each final sector would receive an infinitesimal amount of material from each of an infinite number of preceding sectors, since the number of contributing sectors after each division of the main stream increases exponentially. In practice, however, a sufficiently fine dispersion of the media in the main stream is obtain after a few divisional operations such as described.
There are, of course, a number of ways in which the principles of this invention may be carried out in order to insure that each subsequent sector receives material from a number of preceding sectors. It is preferred, in accordance with this invention, that the cross-sectional shape of each sector be elongated during the relative displacement of adjacent sectors, with a corresponding reduction in height in order to maintain the same overall area throughout. Consequently, if the exit or discharge end of a sector is superimposed upon the entrance of the mixing apparatus, it can be seen that the elongated crosssectional shape will overlap not only its own entrance end but also the entrance end of at least two adjacent sectors. An additional advantage to this process is that the various materials to be mixed in the adjoining sectors have a greater area of contact with one another after reuniting, which promotes homogenizing of the main stream by diffusion of the materials into one another.
Although the cross-sectional shape of materials contained in the main stream prior to division into sectors could be rectangular, square, or any other desired configuration, it is preferred that one of the materials be closed upon itself in order to eliminate many of the disturbing edge effects. This may be obtained by forming the supply streams of the materials to be mixed into an initial main stream of annular cross-section and by reuniting the homogenized material into a subsequent main stream having the same cross-sectional area as the initial stream. Moreover, it is preferred that the supply streams of the different materials be disposed in such a manner that the main stream initially formed by introduction of one material into the stream of the other will consist of concentric 3 annular portions. An advantage to this treating system is that more uniform heating or cooling can be accomplished if such is necessary or desired.
Although the annular stream of one material may be fed either radially or axially into the annular stream of the other materials, it has been found that a more satisfactory mixing is obtained if the supply streams are combined when flowing generally in the same direction. Statistics have shown that a uniform distribution of the media over the main stream is obtained more rapidly in this manner than by random commingling f the supply streams.
The process described immediately hereinabove is particularly well suited for mixing media whose quantities are of substantially the same order of magnitude. Difliculties may be encountered, however, if one of the materials consists of a high viscous liquid and the other a pigment which is to be mixed in small proportionate amounts.
Mixing of material in a disproportionate ratio may be accomplished in accordance with this invention by shunting a small portion of the high viscous main stream, adding the pigment or other material to the shunted stream, and recombining the shunt stream into the main stream by the use of one or more pumps. This process per se is not a part of the present invention but forms the claimed subject of companion application Serial No. 655,004, filed April 25, 1957, now Patent No. 2,929,731 owned in common with this application. This main stream may then be subdivided into sectors for homogenizing in the manner stated above.
Aside from the mixing of high viscous liquids and pigmerits, this invention also relates to the homogenizing of flowing gases, liquids having similar or different properties, or granular materials other than pigments. The apparatus contains no moving parts and consists essentially of a supply line, a discharge line, and at least two mixing members disposed therebetween. At least two longitudinal channels should be provided in each mixing member to permit division of the supply into sectors, displacement of sectors, and alteration of cross-section as described previously. The discharge end of a channel should be rearranged or displaced not only with respect to the corresponding entrance end of that particular channel, but also with respect to other channels in that mixer.
A very successful mixing action may be obtained if a plurality of identical mixers are placed in series in a suitable mixing zone or tube, and if the baffles are constructed so as to alter the main stream from a plurality of sectors arranged in a single row at the entrance end to relatively displaced oblong or elongated sectors arranged in two parallel rows at the discharge end. As stated earlier, the sectors could have any desired cross-sectional shape. In accordance with this invention, however, one dimension of the sector at the entrance end should be reduced by about half at the discharge end, while the other dimension should be doubled during the alteration in shape in order to maintain constant the cross-sectional area. One satisfactory manner in which this alteration may take place is through the use of a transition zone substantially midway between the entrance and discharge ends of the longitudinal channel defined by each pair of baflles. In the first part of the channel one dimension may be reduced by half while the other is kept constant, and the other dimension may be doubled during the second part of the channel while the reduced dimension is maintained constant.
Although the sectors discussed above could be rectangular, square, etc., it is preferred according to this invention that ring-like sectors be formed by dividing an annular stream radially into components disposed about the periphery thereof, or consecutive peripheral channels. Each sector or channel therefore may be defined in cross-section at the entrance end of a mixer by an outer curved surface, an inner curved surface, and a radial surface on each side. The annular stream should be divided into a plurality of such sectors, each having the same shape and dimensions in cross-section. The material passing through a first channel should be displaced outwardly to occupy a space having only half the original radial length but twice the original circumferential length. That material passing through channels immediately adjacent to the first-mentioned should be displaced inwardly also to occupy a space having only half the original radial length but twice the original circumferential length, and so on throughout the annlar stream. Consequently, the annular stream is divided into consecutive radial sectors upon initial contact with a mixer, but emerges from the mixer in alternate outer and inner sectors of reduced radial dimension but doubled circumferential dimension, which not only displaces one sector radially with respect to adjacent sectors but also compresses the layers constituting the supply of material to be mixed and spreads the same over a greater circumferential area. This system operates most effectively if the materials to be mixed are supplied in two concentric annular streams to form a main stream of annular cross-section prior to introduction into the first mixer unit.
Other objects and advantages of this invention will become evident upon study of the following detailed disclosure of a preferred embodiment taken in conjunction with the accompanying drawings, wherein FIGURE 1 is a perspective view of one mixer unit suitable for use in accordance with the principles of this invention, with the discharge end facing the viewer;
FIGURE 2 is a sectional view taken along the lines 22 of FIGURE 5 illustrating the entrance of two representative sectors from concentric annular streams of material into a mixing apparatus containing a mixer unit such as shown in FIGURE 1;
FIGURE 3 is a sectional view taken along the lines 33 of FIGURE 5 illustrating the combined alteration in shape and relative displacement, both radially and circumferentially, produced by the first mixer unit upon passage of the aforesaid two representative sectors therethrough;
FIGURE 4 is a sectional view taken along the lines 4-4 of FIGURE 2 illustrating the radial displacement only of streams passing through two adjacent sectors of a single mixer unit; and
FIGURE 5 is a schematic view, partially in section, illustrating a complete mixing apparatus including a plurality of the mixer units shown in FIGURE 1, suitable conduits for supplying two different materials in concentric annular streams, and a discharge conduit for combining the blended streams into a main stream and for feeding the same to other processing apparatus, not shown.
With attention first directed to FIGURES 2 and 3, a further explanation of the change occurring during passage of material through one mixing stage will be given. In these figures reference numeral 10 represents an outer tubular conduit within which the mixer unit 11 is snugly positioned. An inner tubular conduit 12 completes the assembly and together with conduit .10 defines an annular passageway which receives the mixer unit.
At the outset it shoud be pointed out that a plurality of mixer units 11, preferably of identical construction mounted either in staggered or aligned relationship, are placed in series between the outer and inner conduits 10, 12, as shown in FIGURE 5. For purposes of illustration the outer layer or annular ring of material 13 has been cross-hatched to indicate red pigment and the inner layer or annular ring 14 has been cross-hatched for liquid, although it should be understood that this invention is not limited to the mixing of two materials only, to the mixing of pigment with liquid, to division into the precise crosssectional shapes shown, or to mixing of materials in the ratio shown.
Although only two sectors or channels 15, 16, as shown in FIGURE 2 are *filled with material to be mixed, it is pointed out that the entire annular zone between the outer and inner conduits is filled with material flowing normally into the plane of the figure. The two sectors 15, 16 are separated from each other by one of the plurality of radial bafiles 17 disposed circumferentially around the mixer unit 11 and from other radial sectors by the other baflles, as shown. By means to be described shortly, the radial sector 15 is shifted or displaced from the FIGURE 2 position to the outer position shown in FIGURE 3. During the transfer from the FIGURE 2 to the FIGURE 3 position this sector was altered in cross-section from a generally elongated shape in a radial direction to one elongated in a circumferential direction. In other words, the major axis of the sector extends circumferentially and the minor axis extends radially, which is a reversal of the initial configuration where the major axis extended radially and the minor axis extended ciroumferentially. This changed shape inherently produces a reduced thickness of the layers 13, 14, but spreads them over a sufliciently greater circumferential portion to maintain a constant cross-sectional area. The flattened discharging sector 15 of FIGURE 3 is symmetrically disposed about the more squarely shaped sector entering the mixer in FIGURE 2, as can be detected by comparison of the figures or upon consideration of the outlets shown in dotted radial lines in FIGURE 2.
Simultaneously with the passage of sector 15 through the mixer unit 11, adjacent sector 16 undergoes a similar transition, but in this case is transferred inwardly as evidenced by the FIGURE 3 position. Consequently, the consecutive sectors 15, 16 entering the mixer as full radial segments of the annular main stream of materials are transformed not only into different shapes but also into inner and outer sectors staggered one with respect to the other. The inner and outer components 15, 16 emerging from the mixer are radially separated, at least temporarily until complete discharge from this particular mixer, by a ring-like divider 18 which forms a base for the remaining elements of the mixer unit, which will be discussed presently. This divider 18 is so disposed with respect to said other elements of the mixer that the streams of liquid entering adjacent sectors such as 15, 16 are equally divided and have substantially the same radial dimension in the FIGURE 3 position.
If the baffles 17 on the immediately subsequent mixer unit 11 are in alignment with the first mixer shown in FIGURES 2 and 3, a portion from each of the two sectors 15, 16, as well as from sector 20, will form the squareshaped entrance sector for this second mixer, as illustrated by bracket 21 in FIGURE 3. The material discharging from this portion of the second mixer unit 11 will be identical in cross-section to the sector 15, and located in the same position relative to the mixer, but will be composed of four layers 13, 14, 13, 14, since the bafiles 17, 17 will remove a slice from the full radial distance between conduits 10, 12, which of course includes a part of the outer sector 15 and parts of adjacent inner sectors 16, 20. In this manner of operation, material from adjacent channels actually is inter-mixed during each passage through a mixer unit. This of course contributes to homogenization of the main stream forming the concentric annular streams.
With the balfles 17 on successive mixer units in alignment as mentioned, the material channelled into the second mixer will contain an equal portion from each of sectors 16, 20, and a portion from sector 15 about equal to the total from sectors 16, 20. Staggering of baffies on succeeding mixers will result in changing the quantity of material removed from one preceding inner sector relative to the other inner sector. This effect is the same as shifting the bracket 21 circumferentially about the tubular conduits. 'It is apparent, therefore, that a consistently uniform interchange of material from the greatest number of preceding sectors can be obtained if the mixers are mounted in alignment, although exchange of material from at least two preceding sectors is possible even if the mixers are staggered one with respect to another.
The preferred apparatus for performing the foregoing functions will next be described, with particular attention directed to FIGURE 1. As stated earlier, the discharge end of mixer unit 11 appears in the foreground, with the entrance end of course in the background. The unit 11 is provided with twelve baflles 17 as shown, each baffle extending radially for a sufficient distance to bridge the space between outer and inner conduit-s 10, 12, when the mixer is installed therein. The baffles 17 operate in pairs to divide the supply stream in a manner fully explained hereinabove.
Formed integral with or secured in any suitable manner to the divider ring 18 are two concentrically disposed circular rows of projections each of which facilitates the transition of individual channels from the FIGURE 2 position to that shown in FIGURE 3 and separates circumferentially adjacent sectors. 'One row of separators extends inwardly from the divider '18 and the second row, staggered with respect to the first, extends outwardly. The outermost, or outer, separators 22 consist essentially of a solid body portion 23 which is wedge-shaped and terminates at the discharge end in a sharp edge 24 extending generally radially of the mixer. The wedge-shaped body portion 23 of separators 22 provides faces 25, 26 which slope in such a manner as to permit flattening of the stream of material flowing through a sector defined by two adjacent separators 22, 22. The leading end of body portion 23 is provided with a sloping face 27 (see also FIGURE 4) which deflects a full radial segment inwardly into the elongated discharge end of the mixer to form inner sectors such as 16, 20 in FIGURE 3.
The inner separator-s 28 are substantially identical to the outer separators with the same wedge-shaped body portion and sharp trailing edge, but operate to deflect alternate full radial segments outwardly to form sectors such as 15 in FIGURE 3. These inner separators 28 are wedge-shaped at the trailing end 30 and have sloping faces 31, 32 similar to the faces 25, 26 on the outer separators. Moreover, each inner separator is provided with a sloping surface 33 at the entrance end, also as shown more clearly in FIGURE 4.
With attention directed to 'FIGURE 4, it can be seen that material flowing into the sector 16 follows the direction of arrow 34 and is displaced downwardly by the sloping surface 27 on the body 23 of the outer separator. On the other hand, material entering into the sector immediately adjacent to 16 follows the path illustrated by arrow 35 and is deflected outwardly by the sloping surface 33 on the body 30 of the inner separator 28. This operation of course is repeated throughout the mixing apparatus, it being pointed out that the transition shown between FIGURES 2 and 3 occurs simultaneously with the reduction in thickness illustrated by FIGURE 4. It will be appreciated from the foregoing that the number of layers of material is doubled during the passage through each mixing unit, but that the thickness of individual layers of course will simultaneously be reduced and spread over a larger area circumferentially around the units 11.
If, for example, ten mixer units are arranged in series, and the thickness of each of the entering layers of colored and uncolored material is assumed to be 1 cm., then the thicknesses of the layers discharging from the apparatus will be reduced to 0.01 mm. Consequently, the main stream will be rapidly homogenized by diffusion of the media into one another upon overlapping of adjacent sectors.
Attention is now directed to FIGURE 5, which illustrates a preferred manner in which two concentric streams may be blended initially into a main annular stream for introduction into a mixing apparatus such as described above. In this figure, fifteen mixer units are positioned in series within the outer tubular conduit 10' and the inner tubular conduit 12, although only four are shown. A main conduit 36' supplies viscose, in this example, to the mixing apparatus, and a container 37 furnishes the red pigment chosen for discussion. In order to introduce the pigment into the' viscose in the manner fully explained 7' by aforesaid application Serial No. 655,004, it is preferred that a portion of the viscose stream be shunted and combined with a portion of the pigment, after which the highly concentrated viscose-pigment solution may be combined with the main viscose supply.
The procedure for mixing the pigment will not be described in detail herein. Suifce it to say that a portion of viscose from supply conduit 36 is shunted through pipes 38, 40mm annular compartment 41. Pumps 42, 43 are provided for performing this operation, and for introducing the pigmented viscose into the compartment '41. The pump '43 must have a higher capacity than that of pump 42, of course, in order to accommodate the increased volume of material caused by initially combining the Viscose and pigment, also as explained in said copending application.
Annular compartment 41 surrounds the widened portion 44 of supply conduit 3-6, as shown in FIGURE 5, and provides the outer annular stream cross-hatched as red pigment in FIGURE 2. The portion 44 of conduit 36 supplies the inner annular stream represented as liquid in this figure. If desired, steel wool or other porous material 45 may be packed within annular compartment 41 to insure thorough preliminary mixing of the shunted viscose and pigment. This material of course could be eliminated if such preliminary mixing were not necessary or desired, for example, when mixing two materials having approximately the same consistency.
Moreover, in the event that the longitudinal dimension of the compartment 41 and portion 44 of supply conduit 36 is not sufficiently long to align the two layers as shown in FIGURE 2, it may be desired to add flow straighteners 46. Four of these straighteners have been shown in FIG- URE 5, but of course the number depends on the length of compartment 41, portion '44, and the turbulence of the material introduced into the mixing apparatus. After passage through the mixer units 11, the blended material flows through terminal portion 47 of the apparatus which eventually converges into a continuation of the main conduit 36, illustrated at 48.
With the foregoing discussion in mind, it will be apparent that a stream of viscose may be supplied through conduit 36 into the mixing apparatus. This viscose diverges as indicated by arrows (see FIGURE 5) and flows into the widened portion 44. In the meantime, a portion of viscose has been shunted through pipe 38, is preliminarily combined with pigment fed from container 37 by pump 42, and is finally forced into the annular compartment 41 by second pump 43.
The two annular streams emerge from the compartment 41, and widened portion 44, respectively, in concentric layers, and pass through the ilow straighteners into the mixer units proper. The annular streams are introduced into the first mixer 11 in the manner shown at 13, 14 by FIGURE 2, and are discharged from this mixer as shown in FIGURE 3 with each sector flattened, or reduced in one dimension while being elongated in the other. Thereafter, the materials are passed directly into a second mixer unit 11 which divides the streams into another twelve radial sectors illustrated by bracket 21 in FIGURE 3. These sectors also are flattened as described above, and pass directly into a third mixer unit. The four concentric streams discharging from second mixer unit 11 are of course doubled so that eight concentric streams emerge from this third mixer. This process is repeated, in the example given, until the material flows through fifteen different mixers. It will be appreciated that the thickness of the layers 13, 14 originally introduced through compartment 41 and portion 44, respectively, is repeatedly reduced to a minute amount and the mixture discharging through terminal portion 47 is thoroughly blended. Materials other than viscose and pigment of course could require either fewer or greater units for homogenization, depending on the material processed. The steel Wool serves to split up the concentrated mixture introduced at pipe 40, thus insuring that this particular stream is completely homogenized by diffusion of the pigment into the high viscous liquid.
In an alternative construction, it is possible to introduce the material in a rectangular or square conduit forming a stream composed of parallel adjacent layers. In this event, the baffles for dividing the stream into sectors would not be radial as shown at 17, but would extend in parallel along planes normal to the longitudinal axis of the streams as viewed in cross-section. The longitudinal axis of each layer of course would be rotated 90 upon passage through a mixer unit, and the following mixer would slice through at least two adjacent sectors in the manner described above.
If the liquids or materials to be blended are supplied in quantities of the same order of magnitude, the shunt system shown at 3 8, 40, etc., is not necessary. Two main supply conduits such as 36 could be provided, with a transition area in one for supplying the material contained therein to annular compartment 41.
A good homogenizing effect and thorough mixing is obtained if, according to this invention, the channels have a cross-sectional shape upon introduction to a mixer unit which so changes upon discharge therefrom that the profile becomes more oblong. In other words, the quotient of the circumference and the square root from the area of these entering and discharging cross-sections should increase.
Although the transition zone of a channel passing through each mixer unit has been shown to make rather abrupt changes (see FIGURES l and 4, for example), it is obvious that the surfaces could be rounded in order to provide a more streamlined flow in the event such is necessary or desired, such as when processing extremely high viscous material. Moreover, the mixer units may be formed from any suitable materials, for example, by casting into an integral piece, or the separators could be formed individually in the manner of turbine blades and thereafter secured to the supporting divider 18. In the latter case, a plurality of identical components could be constructed for subsequent assembly. Additionally, it is possible that the separators could be cast in half sections. In this event, two separate molds would be necessary, since alternate half sections would be mirror images one of the other.
Inasmuch as various other modifications will become apparent to those skilled in this art upon study of the preceding detailed disclosure, it is intended that the scope of this invention be limited only to the extent set forth in the accompanying claims.
What is claimed is:
1. A process for mixing at least two streams of flowing materials comprising the steps of combining the streams into a single main stream, dividing the main stream into a plurality of partial streams, each having major and minor axes in cross-section, and displacing at least one partial stream with respect to an adjacent partial stream while altering the cross-sectional shape so as to reverse the major and minor axes thereof.
2. A process for blending at least two streams of flowing materials comprising the steps of combining said flowing streams into a first main stream, dividing said first main stream into a plurality of first sectors flowing adjacent to one another, each first sector having major and minor axes in cross section, displacing each first sector with respect to adjacent first sectors while changing the cross-sectional shape to such an extent that the major and minor axes are reversed and each first sector overlaps at least one adjacent sector, recombining said first sectors into a second main stream, and thereafter dividing said main stream into additional sectors each receiving a portion of material from the space occupied by at least two of said overlapped sectors.
3. Apparatus for blending at least two streams of flowing materials comprising means for combining said streams into a first main stream, means for dividing said first main stream into a plurality of first sectors, each first sector having major and minor axes, means for displacing at least one of said first sectors with respect to adjacent first sectors while simultaneously changing the cross-sectional shape thereof to such an extent that the major and minor axes are reversed, means for recombinling said first sectors into a second main stream, and means for dividing said second main stream into a plurality of additional sectors, each receiving a portion of material from at least two of said first sectors.
4. Apparatus for blending flowing materials comprising means for forming a first main stream of annular cross-section from concentric layers of flowing materials, means for dividing said first main stream into a plurality of channels disposed oircumferentially therearound, each channel having major and minor axes and each channel containing material from each of said layers, means for displacing at least one of said channels with respect to adjacent channels while simultaneously changing the cross-sectional shape thereof to such an extent as to reverse the major and minor axes and overlie adjacent channels, means for recombining said displaced channels into a second main stream, and means for dividing said second main stream into sectors each receiving a portion of material from at least two of said channels.
5. A mixing apparatus comprising an outer tubular conduit, an inner tubular conduit, at least one mixer unit bridging the space between said inner and outer tubular conduits, said mixer unit comprising an annular divider concentrically mounted in the space between said conduits, a plurality of outer separators secured to the outer surface of said annular divider, a plurality of inner separators secured to the inner surface of said annular divider in staggered relationship with respect to said outer separators, each of said outer and inner separators having a wedgeshaped body portion terminating in an edge extending generally radially of said annular divider, a radially extending baffle secured to each side of said body portion, and means defining a sloping surface extending from one surface of said body portion between said baffles to the opposite surface thereof.
6. A mixing apparatus comprising a conduit of uniform cross section for supplying a main stream of unmixed materials to be blended, means within said conduit for dividing said main stream into at least two partial streams, means within said conduit for displacing one partial stream relative to the others While simultaneously altering the cross sectional shape of each, means within said conduit subsequent to said displacing means for at least once simultaneously sub-dividing each of said partial streams into at least two sub-partial streams, the sub-partial streams resulting from each sub-division corresponding in number to said partial streams, means within said conduit for displacing each sub-partial stream relative to the others while altering the cross sectional shape thereof, and means within said conduit for directly combining corresponding subpartial streams into modified partial streams and modified partial streams into a modified main stream to thoroughly blend said materials.
7. A mixing apparatus comprising a conduit of uniform cross section for supplying a main stream of unmixed materials to be blended, means within said conduit for dividing said main stream into first and second partial streams, means within said conduit for displacing one partial stream relative to the other while simultaneously altering the cross sectional shape of each, means within said conduit for simultaneously subdividing each of said partial streams into first and second sub-partial streams while again altering the cross sectional shape thereof, and means within said conduit for directly combining sub-partial streams from the first partial stream with sub-partial streams from the second partial stream in corresponding pairs to produce modified first and second partial streams.
References Cited in the file of this patent UNITED STATES PATENTS 1,204,163 Kusebauch Nov. 7, 1916 2,094,948 Hurley et al. Oct. 5, 1937 2,230,221 Fitch Feb. 4, 1941 2,426,833 Lloyd Sept. 2, 1947 2,553,141 Maynard May 15, 1951 2,554,167 Anderson May 22, 1951 2,869,837 Pickin Jan. 20, 1959 FOREIGN PATENTS 237,901 Germany Sept. 13, 1911 959,155 France Sept. 21, 1949
Citations de brevets