US2779574A - Mixing or stirring devices - Google Patents

Description

Jan 29, 1957 J. SCHNEIDER MIXING 0R SIIRRING DEVICES 2 Sheets-Sheet l FIIed Jan. 7, 1955 Jan. 29, 1957 J. SCHNEIDER 2,779,574

MIXING OR STIRRING DEVICES Filed Jan. 7, 1955 2 Sheets-Sheet 2 Wim/@Zinn This invention relates to mechanical mixing or stirring devices.

United States Stirrers are used, particularly in the chemical industry,` `5

but also in other branches of industry, for the purpose of mixing, stirring and circulating liquids of different consistency and specific gravity. The stirrers are constructed as fork, blade or propeller stirrers. The greater number of these constructions permit mixing in one direction` only,

unless the direction of rotation is changed( In addition, these stirrers usually run in a bearingin the bottomY of the agitator vessel, which has frequently caused difficulties in practice. Stirrers of this type are `usually driven through gears or belt pulleys. p l

The main object of the present invention is, to provid a new mixer by means of which smoothrunningof mixer is ensured with long driving shafts. A further object of the invention is to provide anv improved mixture by a new construction` of the stirring arrangement.

The invention inally aims at new constructions of rotary mixers, in which Aan improved mounting of the mixer shaft with an improved `stirrer or mixer head is obtained. H

Accordingly the invention provides a rotary mixercoinprising in combination a support member, a dependent tube secured to said support member, a shaft mounted for rotation in said tube and having a mixer blade secured to the lower end of said shaft, said tube having at the lower end thereof a bearing above said mixer blade.

Two forms of construction of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure l shows a longitudinal section through a complete mixer,

Figure 2 shows a longitudinal cross section through a blade of the mixer,

Figure 3 shows a section on the line III--III in Figure 2,

Figure 4 shows a section on the line IV--IV in Figure 2,

Figure 5 shows a partial elevation of the mixer blade seen in the direction of the arrow E in Figure 3, and

Figures 6, 7 and 8 are views similar to Figures 3, 4 and 5, respectively, of a modied form of the invention.

In the embodiment illustrated in Figures l-5, a supporting flange 1 is provided, which carries two ball bear-t ings 3, 3 in a stuffing box housing 2 disposed above said flange. A shaft packing indicated generally by numeral 4 is also provided in the ange 1 and may be a stung box packing. If necessary, a sliding ring packing may be provided instead of a stuffing box packing, particularly in the case of higher pressures. 5 indicated a driving shaft for the stirrer blade, said shaft being disposed vertically and carrying at its upper end a jaw coupling part 6, which may co-operate with a jaw coupling part 7 on a driving shaft 8. It is possible to couple the shaft 5 directly to a driving motor, particularly a vertical motor (not illustrated) without a gear being interposed.

A shaft-protecting tube, which bears the general ref- 2,779,574 Patented Jara. 28, i957 erence 9 and which consists, in the exemplified embodi rnent illustrated, of a plurality of parts 10, 11 and 12 which are connected together by tianges, extends down'- ward from the supporting flange 1. At an intermediate poiritwof "the shaft-protecting tube 9, a sliding bearing fend Aa mixer blade which is indicated generally by the reference numeral 18 and the individual parts of which are described hereinafter with reference to Figures 2 to 5.

rl`he mixer vblade has `a body part 19 with an internal bush 20, which can beplaced over the lower end 21 of the vertically mounted shaft 5 and secured there by using a head threaded nut 22 or the like.

The mixer blade indicated generally by numeral 18 is constructed in the embodiment illustrated as a self-contained, double-ilow mixer blade having blades running in the same-directions.` ln crosssection, its shape diverges from the circular, as may be seen particularly from the presentation in Figures 3 and 4. The mixer blade has Va middle `transverse wall 23 which carries, on one side thereof oppositely disposed mixer blade members 24, 24 whosecross-sectional shape may be `seen clearly from Figure f3. The blade members 24 are closed off at their upper ends` by a` Wall 25 integral therewith. In this wall 'a eo-axial annular inlet 26 is provided for the material to be mixed. The mixer blade is open at the peripheral at' 26, isstruck by the blade members 24, 24 and reemcrges at the `periphery from the outlet slots 27, 27.

The `blade arrangement on the underside of the transverse wall`23 is of similar construction. Blade members 28, 28 (Figure 4) are provided, which run in the same direction as the blades 24, 24 and the blade members 28, 28 are closed oli at their lower end by an integral wall 29. In this lower wall an inlet aperture 30 is provided for the material to be mixed, and its total crosssection corresponds approximately to the cross-section of the annular inlet 26. The blade members 28, 28 on the underside of the transverse wall 23 have a profile as shown in Figure 4 for example. The material to be mixed is in this case guided in a manner corresponding to that with the blade members described above, and it enters from below through the aperture .30 and after being struck by the blade members 28, 28 re-emerges from the mixer blade at the periphery at 31.

As is clear from Figures 3 and 4, the cross-sections 0f the outlets 31 of the lower set of blade members 28, 28 are smaller than the outlet cross-sections of the set of blade members 27, 27. The construction may also be selected so that the reverse obtains, the shorter blade members having a larger outlet crossasection being disposed at the bottom and the longer blade members with the smaller outlet cross-section being disposed at the top of the mixer blade, as' shown in Figures 6 and 7.

As a result of the above characterised construction of the mixer blade the advantage is provided that, when the mixer operates, the medium or material to be mixed or stirred is simultaneously sucked in from above and below the mixer bla-de 1E. As a consequence of the different lengths of the blade members 24, 24 on the one han-d and 23, 28 on the other hand, and similarly, as a consequence of the different outlet cross-sections of the two sets of bla-de members, the partial mixtures flowing out of the outlets 27 and 31 respectively have different velocities, and .as a result of these different velocities a third mixing is effected at the outlets of the o blade, said third mixing merging, as a result of the con'- struction of the blade, into a pulsation perpendicular to the shaft of the mixer, rotation of the material being capable of being reduced or practically eliminated.

During rotation of the mixer blade 18 a suction effect is created at inlets 26 and 30 and solid particles deposited at the base of the vessel accommodating the material to be mixed, or suspended substances loating on the surface of the material to be mixed are in each case drawn into the inlets 26, 30 of the mixer blade and intimately mixed with the main medium.

The mixer according to the invention further has the advantage that the direction of rotation of the mixer blade need not be changed, irrespective of whether the material is sucked in from above or below.

A rotary mixer according to the invention is capable of being used for the intensive mixing of media of the most diverse kinds, for example:

Acidsl and liquors of all kinds Liquids with solids Liquids with viscous media Sludges of all kinds Cellulose and paper pulps Liquids with air I claim: 1. A rotary mixer comprising in combination a support member, a shaft mounted for rotation on said support vmember and bearings for the shaft, a mixer blade secured to the shaft and having a non-circular cross section, said mixer blade comprising a unitary hollow body with an upper and lower wall and having a partition element interposed between the walls to define upper and lower separate passages in the body transverse to the axis of ro- 1 3. A rotary mixer according to claim l, characterized in that the cross section of the lower passages is larger than the cross section of the upper passages.

4. A rotary mixer according to claim l, characterized in that the outlets from the lower passages on the lower side of the mixer blades have a cross section larger than the outlets of the upper passages on the upper side of the mixer blade.

5. A rotary mixer according to claim l, characterized in that the outlets from the upper passages on the upper side of the mixer blade have a cross section larger than the outlets of the lower passages of the lower side of the 4of said partition element is less than that of the blade elements on the upper side of said partition element.

8. In a mixer, a blade of ellipse-like shape -in cross section and comprising a unitary hollow body with an upper and lower wall and having upper and lower passages of Ydifferent cross sections defined therein by a further wall ,therein transverse to the axis of rotation of said mixer blade and blade elements perpendicular to said transverse wall at either side thereof, the inlets to said passages 'being concentric with the axis of rotation of said mixer blade and the outlets from said passages being disposed at the periphery of said mixer blade, said blade elements on one side of said transverse wall extending in the same direction as those on the other side thereof.

References Cited in the file of this patent UNITED STATES PATENTS 127,030 Daniels May 2l, 1872 2,635,860 McLeob Apr. 21, 1953 21,684,273 Fears et al July 20, 1954

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