US3815835A

US3815835A - Disaggregation apparatus for producing fine dispersions

Info

Publication number: US3815835A
Application number: US00245162A
Authority: US
Inventors: T Apostol; J Barna; T Majtenyi; A Egri; Z Kaplar
Original assignee: Banyaszati Kutato Intezet
Current assignee: Banyaszati Kutato Intezet
Priority date: 1972-04-18
Filing date: 1972-04-18
Publication date: 1974-06-11
Anticipated expiration: 1991-06-11

Abstract

Disaggregation apparatus for producing fine dispersions comprises a rotary disc and a stator disc having circular rings of teeth protruding into each other and arranged side-by-side with the rings of stator teeth disposed in alternate relation with the rings of rotor teeth, all the rings of teeth being concentric with each other. The space between the teeth comprises apertures identical in number and width for each tooth ring. The apertures both in the stator disc and in the rotor disc are rearwardly inclined relative to the direction of rotation, the differences between the angle included between the center line of the apertures of the stator and rotor discs and the radii from the axis of rotation decreasing in a radially outward direction. In other words, the apertures are progressively less rearwardly inclined in a radially outward direction.

Description

[ June 11, 1974 DISAGGREGATION APPARATUS FOR PRODUCING FINE DISPERSIONS Inventors: Tamas Apostol; Janos Barna; Alaios Egri; Zsigmond Kaplar; Tibor Majtenyi, all of Budapest, Hungary Banyaszati Kutato Intezet, Budapest, Hungary Filed: Apr. 18, 1972 App]. No.: 245,162

Assignee:

US. Cl 241/188 A, 24l/259.l, 241/261 Int. Cl. B02c 7/04 Field'of Search 241/163, 261, 261.1, 261.2, 241/261.3, 188 R, 188 A, 55, 56, 250, 259.1, 244

References Cited UNITED STATES PATENTS 4/1929 Michal 241/261 X 11/1932 Gaiser 241/188 A X 3/1942 Ambrosem. 24l/26l.l X

12/1952 Scherer 241/261 X 1/1955 Rogers 241/56 X 12/1962 Aldred et a1 241/56 X FOREIGN PATENTS OR APPLICATIONS 9/1920 Netherlands 241/261 592,689 8/1925 France 241/188 A Primary Examiner-Granville Y. Custer, Jr. Assistant Examiner-Howard N. Goldberg Attorney, Agent, or Firm-Young & Thompson [57] ABSTRACT Disaggregation apparatus for producing fine dispersions comprises a rotary disc and a stator disc having circular rings of teeth protruding into each other and arranged side-by-side with the rings of stator teeth disposed in alternate relation with the rings of rotor teeth, all the rings of teeth being concentric with each other. The space between the teeth comprises apertures identical in number and width for each tooth ring. The apertures both in the stator disc and in the rotor disc are rearwardly inclined relative to the direction of rotation, the differences between the angle included between the center line of the apertures of the stator and rotor discs and the radii from the axis of rotation decreasing in a radially outward direction. In other words, the apertures are progressively less rearwardly inclined in a radially outward direction.

1 Claim, 5 Drawing Figures PATENTEBJUN I I 974 SHEET 10F 2 DISAGGREGATION APPARATUS FOR PRODUCING FINE DISPERSIONS This invention concerns a disaggregation apparatus for producing fine dispersions continuously while using substantially less power and in considerably less time than known disaggregation apparatus.

In numerous industrial fields, e.g., food canning, various chemical processing, organophilic clay manufacturing, water purifying, ground level and underground building, manufacture of fine ceramic materials, enamels and paints, hydraulic binders, building materials, plastics foams, etc., the attainable or attained degree of fineness is of great importance, because achieving an optimum degree of fineness enables appreciable material consumption savings and a substantial improvement in the produced material quality to be made.

To reach the appropriate degree of fineness it was formerly usual to employ a variety of wetting, comminuting, grinding and mixing processes which in more recent times have been replaced by techniques utilizing shear or impact; in turn, these have been replaced by selecting the most appropriate disaggregation process for the material in question employing impact in combination with shearing. Disaggregation by impacting while also shearing is more successful and more up-todate than all other hitherto known processes. Nonetheless, it has not been adopted to its merited extent; the reason is that it has not so far been possible to produce apparatus able to carry out the disaggregation processes on the appropriate scale and in the required quality over prolonged operating periods. Above all, with known disaggregation apparatus the economics of the results achieved have not been satisfactory.

Known disaggregation apparatus do not allow material recirculation because, if recirculation is used, the

disaggregation process becomes discontinuous. Recirculation is, however, necessary because the structure of the material to be disaggregated (e.g., bentonite and similar materials) and dispersed must be broken down in steps and because, to attain the appropriate shearing action, it is necessary to attain a suitable viscosity value which in many cases can be obtained only be recirculation.

The discontinuous recirculation techniques involved in known disaggregation apparatus entail the risk that individual material portions are subjected to impacts more than others while being sheared; the product obtained is thus inhomogeneous.

In general, known disaggregation apparatus employ a rotary disc with a rim provided with closely spaced teeth and a likewise densely toothed stationary counteracting disc in engagement with the teeth of the first disc. The material to be disaggregated and dispersed streams outwardly from the interior of a vessel containing the disc. Its velocity increases in the outer disaggregation parts and normally a great deal of space is available there for the material, whereby to lead to strong cavitation in the apparatus. As a result of cavitation, relatively little shearing action is exerted on the solid particles and the liquid particles; the energy consumption, too, is high.

A further disadvantage of known disaggregation apparatus is that in them the solid and liquid particles stream ina radial direction and asa result of the ensuing friction lose a large part of their energy in the radially extending flow apertures. The lost energy reduces the amount of energy available for shearing.

A further defect of known disaggregation apparatus is that the shearing action can be changed only by altering the speed of rotation of the rotary disc. As a consequence of cavitation and the very large frictional forces the power consumption is very high and the apparatus suffers relatively rapid wear and then can no longer be used.

An aim of the invention is to seek to provide a disaggregation apparatus which may operate by continuously recycling the material and in which during recycling each portion of the materials to be disaggregated and dispersed undergoes practically the same number of impact and shearing processes; in which the dispersion obtained displays a high degree of fineness and is subtantially entirely homogeneous; in which no cavitation and no substantial frictional forces arise, in which the shearing action can be easily, quickly and continuously changed without altering the operational r.p.m.; which is simple to operate, which functions reliably over prolonged operating periods, and, which, while using relatively little power, will disaggregate and dis perse a relatively large quantity of material in a relatively short period of time.

According to the present invention, there is provided disaggregation apparatus for producing fine dispersions, comprising a bladed rotor disc and a vaned stator disc adapted to rotate relatively to one another and to produce impacts in and shearing of a material flowing there between so as to disaggregate and disperse the material, wherein the successive annular sections of space available for the flowing material, taken at right angles to the direction of flow, are arranged to be substantially of the same size throughout by suitably shaping the blades, vanes and the associated discs, there being respective apertures between circumferentially adjacent blades and vanes for ensuring an oblique material flow relative to the axis of rotation of the rotor, the apertures between adjacent blades of the rotor making an obtuse angle with the direction of rotation of the rotor periphery, viewed in the direction of flow of the material.

A preferred feature of the invention consists in that the shape of the disc surface is, adjacent the blades or vanes, frusto-conical or cylindrical.

The rotor and/or the stator may be mounted in such a way that they can be moved towards or away from each other.

Preferably, opposite blade/vane surfaces of interacting blades and vanes are cylindrical, in axial-flow arrangements. Opposite blade/vane surfaces of interacting blade/vane rims may, however, to frusto-conical, in radial-flow arrangements.

The invention will now be described, by way of example only, with reference, to the accompanying diagrammatic drawings, in which:

FIG. 1 is a section of a preferred embodiment of the disaggregation apparatus according to the present invention;

FIG. 2 is a plan of the rotor and stator of the apparatus shown in FIG. 1;

FIG. 3 is a partial, enlarged cross-section of a modified form of the rotor shown in FIG. 1;

FIG. 4 shows another preferred embodiment of the invention, in broken-away elevation in which the material to be disaggregated and dispersed flows through an annular space along the periphery of the rotor and the disc in the axial direction, and

FIG. shows amoditied embodiment similar to that in FIG. 4 but differing in that here a plurality of alternate rotors and stator discs are arranged in series.

In the embodiment of the disaggregation apparatus according to FIGS. 1 and 2 a rotor I is secured to and for rotation with a shaft 2 rotatable in a

housing having parts

3, 5. The shaft 2 is rotatably mounted in a bearing 4 located in the housing part 3 of the apparatus. A union member 6 adapted to connect the apparatus to a pipe line or to introduce the material to be dispersed into the interior of

thehousing parts

3, 5 extends axially fromthe statorlike housing part 5 and is integrally constructed with the housing part 5, hereinafter referred to as stator 5, or stator disc 5. The introduced material is discharged through a union member 7.

Tooth or blade rings 8 made up of a row of blades are located on the surface of the rotor 1 opposite the stator 5. The rings 8 are mutually spaced radially in such a way that tooth or blade rings 9 on the stator, having spaced apart stator vanes, can be inserted in between. During operation the rings 8 thus rotate between the rings 9 in the direction of the arrow 10 shown in FIG. 2. The radially outermost part acting on the material is a rotor blade ring.

The blades of the rings 8 are constructed so as to form apertures 11 therebetween, the apertures being oblique with respect to the periphery of the blade ring. The direction of the apertures makes an obtuse angle with the direction of rotation of the periphery of the rotor, as viewed in the direction of material flow. Thus the side surfaces of these apertures exert a similar action on the material as e.g., the rotating impeller wheel of a centrifugal pump, i.e., they can elevate the mate-- rial to a certain height or convey it. The general shape of the rotor blades and stator vanes is cylindrical.

In use, the material to be disaggregated and dispersed flows between the teeth of the tooth ring 9 protruding from the stator disc 5, through apertures 12 formed between adjacent stator vanes.

The above-described construction of the

apertures

11, 12 and of the

rings

8 and 9 enables the transfer of the material flowing in-between; and, further, for rheological reasons, ensures that the flowing material streams through the apertures under small frictional forces, or that the particles to be disaggregated are subjected to strong impacts respectively. This mode of flow is very advantageous by comparison with the hitherto employed purely radial mode of flow.

In the diagrammatically shown construction according to FIGS. 1 and 2, the wall of the housing part 3 is vertical with respect to the shaft 2, the top radial surface 13 of the rotor l, on the side of the blades, has a somewhat curved cross-section, while the opposed inner surface of the stator disc 5 is substantially frustoconical. The surface 13 and the inner surface of the stator disc 5, and also the space between the

rings

8 and 9 filled with the material to be dispersed, are shaped and dimensioned in such a way that the annular crosssectional areas, considered at right angles to the material flow direction, are everywhere of substantially the same size. This means that, viewed radially outwards from the axial line 14, the change in radius and hence the change in length of the periphery is balanced out by changes in the width of the annular cross-section for every illustrated annular cross-section. Consequently,

the material entering through the union member 6, while spreading out between the surface 13 and the statordisc 5, flows in such a way that despite an increase in its velocity it fills the space between the surface 13 and the stator disc 5 completely, i.e., substantially no flow-impairing cavitation can arise.

The embodiment according to FIG. 3 (wherein like parts have been allotted like reference numbers) differs from that according to FIGS. 1 and 2 only in what follows. Modified parts retain the same reference number but with the suffix a" added. The rotor blades 8a extending from the rotor 1 are not constructed cylindrically but frusto-conically (are trapezoidal in section). Similarly shaped surfaces define the periphery of the ringsmade up of the stator vanes 9a projecting from the wall of the stator disc 5a. A further difference is that the stator disc 5a may be moved towards or away from the rotor 1. Of the many suitable ways of achieving this, one example is shown: a screw connection 15. Thus the width of the gaps 16 between the side surface of the blades or

vanes

8a and 9a may be varied, and hence the magnitude of the shearing action can be changed without altering the angular speed of the rotor l In the embodiment of the disaggregation apparatus according to the invention shown in FIG. 4 the material to be dispersed that has entered the union member 6 flows only through the outer annular part of a rotor 17 and a stator 18. The rotor 17 has only a single blade ring whose blades fill the entire width of the annular flow section. Opening or apertures. 19 between the blades extend along the full height as the blades. The apertures 19 make an angle with the direction of rotation of the periphery of the rotor 17 equal to the angle between the apertures 11 on the rotor l in the construction according to FIGS. 1 and 2. The apertures 21 between the vanes 20 of the stator 18 are of the same height as the apertures 19. The direction of the apertures 21 is similar to that of the apertures 12 in the construction according to FIGS. 1 and 2.

The construction according to FIG. 5 is essentially similar to that according to FIG. 4, with the difference that, here, a plurality of alternate rotors and stators are arranged in axial-flow series. The width of the gaps between the rotors l7 and stators 18, and hence also the shearing action, can also be constructed to be adjustable.

The principal advantages of the illustrated embodiments of the disaggregation apparatus are the followmg:

Formation of detrimental cavitation effects are substantially prevented or reduced. The magnitude of the frictional forces arising during the flow is reduced by the particular construction of the apertures or gaps between the rotor blades and stator vanes. The result, based on measurements, is that the energy input required for the disaggregating, dispersing and shearing of a given amount of specified material is only 27-29 percent of the energy required in known apparatus.

As a result of the substantial elimination or reduction of the cavitation, the shearing action is substantially increased and it is possible to produce colloidal dispersions of materials which it has not hitherto been possible to disperse to a similar degree of fineness with the hitherto known apparatus or which could be converted merely into coarse-particle dispersions.

A further advantage consists in that as a result of the disclosed pump-like construction of the rotor and the stator the apparatus in addition to a reduced power consumption and a greater shearing effect also displays the property of working as a pump and is able to convey the colloidal dispersion under a pressure of several atmospheres.

The shearing action can be controlled without discontinuities by virtue of the fact that the rotor and the stator, or a plurality of pairs of same, can be relatively axially displaced. The number of pairs of rotors and stators can be selected in accordance with the required technological conditions. Incorporating the pairs in series can be performed quickly with relatively little assembly work. in addition to being used for disaggregation and dispersion tasks the apparatus can be employed also for pre-comminuting coarse-particle materials.

The invention is not limited to the illustrated preferred embodiments. For example the rotor and the stator may be constructed so that they both rotate, for example, in opposite angular senses; the continuous matching of the flow cross-sections to the flow velocity may be performed in an alternative manner to that disclosed above; the size of the angle that the flow apertures (blade/vane gaps) make with the direction of rotation of the rotor periphery may be selected to be dependent on the quality and viscosity of the flowing material; and, when using series-connected rotor-stator pairs, the angles may be altered to match the given technological requirements.

What we claim is:

l. Disaggregation apparatus for producing fine dispersions, comprising a rotary disc and a stator disc each having a plurality of concentric teeth rings, the teeth rings of each of the rotor disc and stator disc protruding between the teeth rings of the other of the rotor disc and stator disc in alternate relationship, the space between the teeth comprising apertures identical in number and width for each tooth ring, the apertures both in the stator disc and in the rotor disc being of backward direction relative to the direction of rotation, there being a difference between the angle included between the center line of the apertures of the stator and rotor discs, and the radaii from the axis of rotation said difference decreasing in a radially outward direction.

Claims

1. Disaggregation apparatus for producing fine dispersions, comprising a rotary disc and a stator disc each having a plurality of concentric teeth rings, the teeth rings of each of the rotor disc and stator disc protruding between the teeth rings of the other of the rotor disc and stator disc in alternate relationship, the space between the teeth comprising apertures identical in number and width for each tooth ring, the apertures both in the stator disc and in the rotor disc being of backward direction relative to the direction of rotation, there being a difference between the angle included between the center line of the apertures of the stator and rotor discs, and the radaii from the axis of rotation said difference decreasing in a radially outward direction.