US3033540A - Mixing apparatus - Google Patents

Description

May 8, 1962 l. ROSIN MIXING APPARATUS Filed Sept. 25, 1959 34 INVENTOR.

IRA ROSIN M m ATTORN EYS nite 3,033,540 MIXING APPARATUS Ira Rosin, 3333 Berkley Road, Cleveland Heights, Ohio Filed Sept. 23, 1959, Ser. No. 841,831 Claims. (Cl. 259-132) This invention relates in general to machines or apparatus for intermixing, dispersing or emulsifying combinations of solids; liquids; gases and liquids; solids and liquids; solids and gases; and liquids, solids and gases in industrial processes. By the term liquids I also intend to include flowable or plastic semi-solids. More particularly, the present invention is directed to improvements in rotary power-driven mixing machines of the impeller type in which the intermixing of the phases of the process materials is accomplished, predominantly, although not exclusively, by a distribution phenomenon known to the art as shear.

Heretofore, in mixing apparatus or mixers, much emphasis has been placed upon using large power input to create high velocity movement of a batch of process materials for the purpose of dispersing the materials into a homogeneous mass. However, I have found that much of this power is consumed in circulatory movement of the mass of the material without effective dispersion. A particular mixing job can be accomplished more quickly, more effectively and with far less power requirement if the power is utilized principally in the desired function of inter-dispersion rather than being misdirected into wasteful circulatory movement of the mass at high velocities.

It is a primary object of my invention to provide a form of mixing apparatus which has improved shear characteristics for effecting the inter-mixing and dispersion of batches of process materials.

Another object of my invention is to provide a mixer of the character described in which means are provided for continuously directing the process materials toward the area of greatest mixing efiiciency.

A further object of my invention is to provide a poweroperated mixer so arranged that a relatively low power input can be utilized for effective mixing procedures.

Still another object of my invention is to provide a mixer of the character described in which the functional components can be adjusted to accommodate a variety of types and characteristics of process materials.

Other objects and advantages of my invention will be apparent during the course of the following description.

FIG. 1 is a perspective view of a power-driven mixer embodying the features of my invention.

FIG. 2 is a vertical cross-sectional view taken as indicated on line 2-2 of FIG. 1.

FIG. 3 is a fragmentary side elevation, partially in section, taken as indicated on line 3-3 of FIG. 1.

Referring more particularly to the drawings, I have shown a powered dual-rotation mixer having a rotatable paddle assembly 10, an impeller or turbine 11 and directional pressure baffles 12.

z The paddle assembly is in the form of a rectangular frame 13 including two' vertically-extending sides 14, which provide paddle blades, and upper and lower, crossbars 15 and 16, respectively, which are joined with the sides 14. The upper cross-bar 15 has provided, centrally thereof, a collar or hub 17 which is in axial alignment with a collar or hub 18 provided on the lower cross-bar 16.

Iournalled for rotation in the hub 18 is one end of a shaft 19 on which is secured the impeller 11. The shaft 19 projects upwardly through a bearing 20, which is mounted in the hub 17, and extends through a casing 21 which houses a speed reducer 22, for a purpose to be described. The upper end or extension of the shaft 19 has a sheave 23 secured thereto which is driven by a belt 24 trained over a sheave 25 which is powered by an electric motor 26. The sizes of the sheaves 23 and 25 are so selected as to produce the desired speed of the shaft 19 and impeller 11, which normally may be within the range of 300 to 1100 r.p.m. depending upon the characteristics of the batch of material to be mixed.

The paddle assembly 10 is secured, at the hub 17, as by pin 27, to the low-speed output shaft 28 of the speed reducer 22 which is driven by an electric motor 29 through a sheave 30, a belt 31 and a sheave 32 secured to the input shaft 33 of the speed reduced. The shaft 28 is hollow to provide clearance for the coaxial shaft 19 which passes therethrough. The motor 29, through the speed reducer 22, drives the paddle assembly at a low speed which normally may be within the range of 15 to 30 r.p.m., depending upon the characteristics of the material to be mixed as well as the relative width or diameter of the paddle assembly. I have found that for most mixing applications, the paddle assembly should be rotated at a speed which will be equivalent to about 230-270 feet per minute at the periphery of the blades 14. Thus, as the paddle assembly is increased in size, it is desirable that its rate of rotation be reduced to maintain a peripheral speed approximating 250 feet per minute. I also prefer that the rotation of the paddle assembly 10 be opposite to the direction of rotation of the impeller 11, so as to increase the number of shearing strokes or shears, as will appear more fully hereinafter.

The impeller 11 includes a plurality of curved blades or vanes 34 which are removably secured, as by fasteners 35 to radially extending stubs 36 which are uniformly spaced on a hub 37. The hub 37 is secured to the shaft 19 for rotation therewith, the direction of rotation being such that the concave faces of the blades 34 lead the movement. By removably fastening the blades 34 to the stubs 36, a blade which becomes broken or bent can be readily replaced without the necessity of replacing .the entire impeller. Furthermore, all of the blades may easily be replaced with a set of blades of different length or curvature, when such is necessary or desirable.

The impeller 11 rotates within a U-shaped cut-out or recess 38 which is provided on the paddle assembly 10 by the upper edge 39 of the cross-bar 16 and the oppositely disposed vertical edges 40 of a pair of impingment or shear blades 41 which are mounted on the cross bar 16. The blades 41 are provided with laterally-elongated slots 42 which are traversed by fasteners 43 for removably securing the blades 41 to the frame 13 of the paddle assembly. The slots permit the position of the blades to be adjusted to provide the desired clearance between their edges 40' and the impeller blades 34. This clearance dimension is generally in the range of A; to 6 inch and depends upon the characteristics of the materials to be mixed.

A pair of baflle plates 12 are secured to the frame 13 in angularly inclined positions with the leading edge 44 of each plate elevated so as to provide an inclined down- .Wardly directed pressure face 46 above the impeller area. The lower portion of each plate 12 is provided with an adjustable lip or extension 47 which is slotted as at 48 and secured to the plate 12 by removable fasteners 49. The position of the extension 47 can be adjusted to establish the desired clearance between the bafile plates and the impeller 11. As shown in the drawings, the bafile plate face 46 has an angle of about 45 to the horizontal plane of the impeller 11. However, this angle may be varied to suit specific mixing applications.

The plates 12 are subject to large pressure forces and therefore they are supported both by the sides 14 of the frame 13 and by reinforcing members or plates 50 which are secured to the upper cross-bar 15 of the frame 13.

apparatus is mounted.

3 The plates 53 also serve to some extent as agitator blades during the mixing process.

in operation, the materials to be mixed are placed in a suitably fitted vat or container (not shown) on which the The slowly revolving bafile plate assembly 10 rotates in one direction (counterclockwise in FIG. 1) While the high speed impeller 11 is rotated in the opposite direction. The sides 14 and bottom cross-bar 16 or" the frame 13 are preferably disposed closely adjacent the Walls and bottom of the container and serve to displace the materials and prevent static accumulations adjacent to the interior surfaces of the container. The crossbar 16 prevents the settling of the material at the bottom and the sides 14 direct the material toward the central portion of the container. To this end, the sides 14 may be angled slightly to have an inward sweeping effect.

The pressure face 46 of the bafile plates 12 displaces the process materials downwardly into the impeller area, as the paddle assembly 10 rotates. Additionally, the materials are pressed and crushed in the throat between the lower edge 45 of the baffle plate extension 47 and the upper edges of the impeller blades 34 and impingement blades 41 so that large lumps, or the like, are rapidly disintegrated. Thus the pressure bafile plates act not only to direct the material downwardly into the impeller but also effect a preliminary shear on the coarser aggregates which may exist or be formed during the initial stages of the mixing process. The bafiles 12 create pressure areas which have a magnitude in excess of one atmosphere and thus exert a positive directional influence on the movement of the process materials instead of rely ing solely upon gravitational or circulatory influences to feed the material steadily to the impeller area.

The process material flows into the impeller area where it is caught up by the blades 34 and pressed and sheared between the blades 34 and the edges 40 of the shear blades 41. Although the predominant number of shears occur at the edges 40, there is also a shearing effect between the upper edges of the impeller blades 34 and the edge diet the bafile, and between the lower edges of the blades 34 and upper edge 39 of the cross-bar 16. The rapidly rotating impeller throws the material outwardly where it is again caught up in the circulatory flow'leading back to the impeller 11. 7

By using a six-bladed impeller, as shown in the drawings, rotating at 1000 rpm, 12,\ shears per minute are effected on the edges 40 of the pair of impingment blades 41. With the paddle assembly counter-rotating at, for example, 30 rpm. an additional 360 shears per minute are obtained on the edges 40. This combination of a high rate of shear with pressure feed to the impeller and rapid circulatory turn-over of the process material is highly elficient and effective to mix and disperse the batch with low energy input. As heretofore mentioned, this is the result of utilizing the energy principally in the actual dispersion and distribution operation rather than in violent and random movement of large masses of materials to create impressive but ineffective turbulence.

The adjustable positioning of the impingement blades 41 and the battle extensions 47 permits the shear effect to be controlled for a wide range of process materials of varying characteristics and phase combinations so that optimum results can be obtained with the same miiring apparatus in different mixing applications.

By the term process materials I intend to include broadly any combinations of solids, liquids and gases which are required to be intermixed and which are amenable to mechanical dispersion processes.

It is to be understood that the form of my invention, herewith shown and described, are to be taken as preferred examples of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. In a mixing apparatus for process materials, the combination of a rotatable impeller assembly, said impeller assembly having a plurality of radial vanes terminating in circumferential shearing edges, a paddle assembly mounted for rotation coaxially with said impeller assembly, shearing edges carried by said paddle assembly, said second-named shearing edges being complementary to said circumferential shearing edges and radially adjacent the latter to create a material shearing zone therebetween, and means carried by said paddle assembly for directing the materials toward said shearing zone in response to rotation of said paddle assembly.

2. A combination as defined in claim 1, in which said vanes are provided with radially extending shearing edges, and said means comprises overlying angularly inclined pressure plates presenting shearing edges adjacent to the radially extending shearing edges of said vanes.

3. In a mixing apparatus for process materials, the combination of an impeller assembly mounted for rotation at one speed about a vertical axis, said impeller assembly having a plurality of radially-extending vanes, each vane presenting peripheral shearing edges circumferentially and radially thereon, a paddle assembly mounted for counter-rotation at a speed substantially lower than said one speed on'said vertical axis, said paddle assembly providmg a recess accommodating said impeller assembly during rotation thereof, said recess being defined by shearing blades presenting shearing edges operatively adjacent to said peripheral shearing edges on said vanes, and an angularly-inclined pressure plate carried by said paddle assembly in overlying relationship to said impeller assembly and forcing said material downwardly into said shearing recess in response to counter-rotative movement of said paddle assembly.

4. Acombination as defined in claim 3, wherein the lower edge of said pressure plate presents one of said shearing edges complementary to a radial shearing edge on said vanes, another of said shearing blades presents a shearing edge complementary to the circumferential shearing edge on said vanes, and said pressure plate converges toward said other shearing blade and said radial shearing edges to define a throat therebetween for the restricted passage of material therethrough.

5. A combination as defined in claim 4, wherein said shearing edge of said pressure plate is mounted for ad justable movement relatively to the radial shearing edges on said vanes, and said other shearing blade is mounted on said paddle assembly for adjustable movement relatively to the circumferential shearing edges on said vanes.

References'Cited in the file of this patent UNITED STATES PATENTS 81,589 Branch Sept. 1, 1868 343,771 Lines et al. V Y June 15, 1886 737,241 Hudson Aug'. 25, 1903 741,946 Truelsen Oct. 20, 19 03 1,116,001 Anderson Nov. 3, 1914 1,997,035 Arbuckle Apr. 9, 1935 2,496,919 Schwarz-Kast Feb. 7, 1950 2,963,281 Reiiten Dec. 6, 1960

Images