Mixer apparatus

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  • . United States Patent- 1191 [111 3,752,447 Chen [45] Au . 14, 1973 g .


    Prima Examiner-Robert W. Jenkins 5 l : Y. 9 d I ' W [7 ] nventor James Chen Longmea ow Mass Attorney-John w Klooster et all [73] Assignee: Monsanto Company, St. Louis, Mo.

    [22] Filed: _ Aug. 16, 1971 [57] ABSTRACT

    [211 App]. No.: 172,147

    US. Cl. ............................... .. 259/10, 23/252 R [52] [51] lnt.Cl ................................... ......... .. 130117/04

    [5s] FleldofSear-ch ....................... .. 259/9, 10, 7, 8, 259/5, 6, 109, 110, 21, 22, 23, 24, 25, 26, 43,

    44, 45, 46, 17s, 68, 69;,23/252 R

    [56] References Cited UNITED STATES PATENTS

    1,630,790 5/1927 Essick ............................... .. 259/178 3,017,164 1/1962 Ayers .......... ..

    3,469,948 9/1969 Anderson .... ..

    3,476,523 ll/l969 Leybourne ....................... .. 259/10

    1 "1 3B 4 E 11111. 5

    3? H148 34 49

    01 o 01 UI b q

    A housing and paddle assembly adapted for use in pro cessing and mixing highly viscous ?uids is provided. The mixer employs apaddle assembly having a shaft which rotates about a horizontal axis. The assembly has at least two pairs of blade members. The members of each pair are symmetrically positioned about the shaft and extend axially in one half of the housing. The blade members of each'pair may be slotted at diagonally op posite outside ends. In operation, the paddle assembly can sweep out substantially all of the housing interior and can produce simultaneously in a ?uid cyclical ver~ tical displacement, rolling action, horizontal displace ment, and,- even, fold over action.

    9 Claims, 11 Drawing Figures '


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  • 3 ,752,447 1



    In processing ?uids, especially viscous ?uids having viscosities generally greater than, say, about 5,000 cen tipoises, it is often necessary to blend therewith addi tives. In mixing operations involving such viscous flu ids, many problems are encountered, and specialized mixing apparatus is desirable and commonly necessary. Complex mechanical and ?uid forces are involved. The art has long sought new and improved mixing means adapted for use with highly viscous ?uids, the end re sult generally desired beingto achieve in such viscous ?uids, or to maintain such viscous fluids in, a substan tially uniform or homogeneous condition in the most efficient manner possible. One problem with conven tional mixing means has been the large amount of power required to drive an agitator placed in a highly viscous ?uid. Another problem therewith has been the difficulty of mixing a liquid of low viscosity (for exam ple, one having a viscosity of less than about 10 centi poises) with one of high viscosity (for example, one having a viscosity of greater than about l0,00_0 centi poises). Still another problemv has been the form and con?guration of the agitator and of the mixer housing relative to the agitator. One class of mixers recognized in the prior art char

    acteristically has an agitator revolving generally (though not necessarily exactly) about a horizontal axis within a vessel or housing which is usually cylindrical. Such class of mixers is suitable (depending upon indi-_ vidual situations) for batch or continuous operation. There has now been discovered a new and improved mixer of this class wherein the mixing'of highly viscous ?uids(for example, of a low viscosity liquid into a high viscosity liquid) can proceed with unexpectedly low power and in arapid and highly efficient manner. This mixer is especially well adapted for use conditions where'the housing is only partially filled with a highly viscous ?uid. The mixer is useful in a wide variety of end use applications involving mixing or agitation of ?uids and produces a type of mixing action heretofore unknown.


    The present inventionv is directed to a mixer which is especially well adapted for use in processing highly vis cous ?uids, but which is also suitable for mixing ?uid or ?uidizable materials generally. The mixer incorpo rates a housing which encloses an interior chamber with side and end walls. The chamber walls are gener ally radially symmetrical (e.g., cross-sectionally circu la_r) with respect to a longitudinal axis extending there through. The housing is preferably adapted to be ori ented during mixer operation so that the longitudinal axis extends generally horizontally. The housing prefer ablyhas an input port above the level of the axis and has an output port preferably below the level of the axis, although a housing with only a single port may be used, if desired, as when an auxiliary ?uid pump is used and the. mixer is not used in a continuous operation. The housing can be formed of any convenient con structionzma'terial though steel is presently preferred. The mixer employs a paddle assembly which has a ro

    tatably mounted shaft which extends generally longitu dinally through said housing and generally parallel to said axis. From the shaft extend tow independnet but







    2 axially adjacent pairs of blade members. The blade members of eachv pair are symmetrically spaced from one another and radially project from the shaft prefera bly to near engagement with interior wall surfaces of the interior chamber of the housing. Thus, if there are only two blade members in one pair, then these blade members are diametrically opposed to one another. Each blade member is generally continuous along its axial length and radial breadth. Each member of each pair may optionally be slotted in the region of their re spective diagonally opposite outside ends (or corners), with the effective total slot cross-sectional surface area in each blade ranging from about 3 to 50 percent of the total effective surface area of such blade (preferably ranging from about 4 to 20 percent thereof), though somewhat larger and smaller surface areas may be used without departing from the spirit and scope of the pres ent invention, as those skilled in the art will appreciate. Preferably, the slots in each respective bladeof such a pair of blades are substantially equally sized and simi larly located at respective diagonally opposite outside ends. The diameter of each such pair of blade members in a paddle assembly in a mixer at any given location along the axis of the shaft except in slot locations is typ ically not less than about 90 percent of the diameter of - the interior chamber of the mixer taken at about the same location. Each such pair axially occupies about one half the interior region or chamber of the housing. The shaft of the paddle assembly is joumaled by ap

    propriate journal means at its opposite end regions in fixed relationship to the housing to adapt the shaft for rotational movements. When the shaft rotates, the blade members of each such pair thus sweep out about one half the interior chamber of the housing. Prefera bly, the shaft axis is coaxial with the housings longit'uf dinal axis. The paddle assembly can be formed of any convenient material of construction, though metals such as settl are presently preferred. Sealing means to prevent fluid leakage between the paddle assembly shaft and the housing are provided in an operating mixer, as those skilled in the art will readily appreciate. The paddle assembly is in a mixer preferably adapted

    to rotate with substantially no contact between blade tips and chamber walls. For operation, a mixer is equipped with drive means for revolvably driving the paddle assembly shaft, including a power head and power transfer means. A paddle assembly when rotat ing during mixer operation with ?uid in the chamber of the mixer housing is preferably, though not necessarily, adapted-to produce a simultaneous combination of _cy clical vertical displacement, rolling action, horizontal displacement, and, even, fold over action. Preferably, the clearance between blade tips and housing wall ranges from about 0.01 to 1.5 inches, depending on mixer size, though preferably, in a mixer of this inven~ tion, the ratio of the clearance between the blade tips and the adjacent chamber walls to the chamber diame- ' ter measured at about the same location at substantially all locations in the chamber along the longitudinal chamber axis except opposite slot locations ranges from about 0.01 to 0.0001. Preferably, in a' mixer, the paddle assembly is operated so as to produce during operation uniform rotational movements of the paddle assembly shaft. individual blade members may be radi ally and/or axially curved. ' The invention is further directed to the paddle assem

    bly itself which is employed in a mixer of this invention.

  • 3,752,447 3


    Turning to the attached drawings, there are seen vari ous illustrations intended to provide a better under standing of the present invention, as follows: FlG.l is a side elevational view of one embodiment

    of a mixer of the present invention; FIG. 2 is a vertical, longitudinal sectional view taken

    through the mixing chamber of the embodiment shown in FIG. 1; _

    FIG. 3 is a diagrammatic representation of the ?uid mixing mechanics in an operating mixer of FIGS. land 2 as seen in a vertical, longitudinal section; FIGS. 4, 5 and 6 are diagrammatic representations of

    the ?uid mixing mechanics in one embodiment of an operating mixer of the present inventio