US2583206A - Apparatus for homogenizing - Google Patents

Description

Jan. 22, 1952. A, G, BORCK ETAL 2,583,206

APPARATUS FOR HOMOGENIZING Filed Nov. 3, 1950 I /v VEN mns TTOR/VEYS Patented Jan. 22, `1952 `iff; 'UNirEosTAT-Es Imi"ENT ori-ICE i Carl Grnn'ng, Stockholm, Sweden, assignors to Aktiebolaget Separator, Stockholm, Sweden,

- acorporationof Sweden Application Noveiner 3, 1950,seria1no. 193,858 In Sweden lDecember 1, 1949 Homogenization is mainlyy a division of par'- y ticles or drops ofV a liquid, dispersed in another liquid, into a greater number of smaller units. The elect of the division is that the particles or drops are less readily separated by gravity or centrifugal force from the liquid in which they `are dispersed. The concept of homogenization also comprises a mixing effect, that is, a unilform-mixing of the particles or drops with the liquid. Thus, homogenized products are characterised by nelycomminuted particles uniformly mixed with the liquid in which they are suspended Vor emulgated.

- Y The homogenization is effected by forcing the liquid containing-the suspended ortemulgated material through `an homogenizing member. in this Way, the material 4dispersed in the lid-uid is iinely comminuted, because, as stated, the particles or-dropsA are latomized into a much larger number of smaller particles or drops, which ,bef- Kcome uniformly distributed in the liquid. Previously, it has been common practice touse an -homogenizingfmember 'in the form of a springpressed valve and seat, the liquid being forced smdr high pressure lthrough .a narrow -slit formed by displacement of thefvalve body from its seat under the liquid pressure.- Thus. the particles Vor drops are 4split' iup vandfatomizeol into a large number of .smaller units. Such homogenization 1o claims. (o1. ass- 4) fof milk, for example, requires .a very high `pressure in the order of perhaps 200 .kg/cm?. This thigh 'pressure in turnnecessitates expensive formed by the three fb'alls together-.with a fourth .ball injt he next plane. In the opening, the .liq-

uid assumes a velocity which depends uponthe pressure Aof the pump which `iokrces the liquid through the ball set. As theba-lls can be made Witlrvery high accuracyand with very smooth =isurfaces :(b'all bearing balls may be usedhthe frictional losses when the liquid passes through set of balls of suitable size.

Ways.

-to the ball diameter.. 'arranged tetrahedromwise, that is, their `centers ing size..

the, opening are small, and the larger part of the energy applied can be Vutilized for conversion intoliqu'id turbulence .friction in the enlarged chamber, the whirl chamber. For this reason, a homogenizing member made .of balls `has a very good homogenizing effect. Experiments have Shown that a certain degree of homogenization is achieved when using a much lower pressure than that which is'ne'ce'ssary in conventional homogenizing members. To obtain the .degree of atomization which requires 200 lig/cm.z Vwith 'known homogenizing memberslof the type referred to, it has been found sufficient to use about l lig/1cm? when the product is forced through a Thus, by using a pump pressure .of kg., it is possible to homogenize normal whole milk, heated to C., down to an average diameter of the fat globules of less .than .1.4 e, of the fat contained in the milk being less than 42 .11. yin size and the largest iat particles being about 2.5 y.. This degree of atomization `corresponds to the .effect ofordinary type .high `p ressure homogenizers operating at a pressure of to 20.0 kg.

The set of balls may .be arranged in different They may, forexample, be enclosed .in a cylindrical casing, the two ends of which are covered .by a grateor the like which .keeps the Aballs .in position. .A .short cylindrical container or `a container of any other `shape Vmay also. be used. The disposition yof the balls which best satisfies the objectof the invention (the balls should all be .of exactly the same size) is that inwhich the balls occupy the minimum volume. The .balls 'then Contact at the largest possible number of points and the `passageways formed .between them will all be alike and will have the smallest upossible throughiiow area in relation The balls yare therefore form one orsseveral contacting tetrahedrons. As mentioned above, the minimum number of balls -is four, and their centers then form a tetrahedron. When Vthe number lof lballs in the set is increased, and when the above condition is `satisiied, the set will form .a tetrahedron of increas- T-he `Vsurest and simplest way of obtaining this disposition, of the balls is when the container .in which the set .is Aheld .is .in the form of a ztetrahedron. The latter need not, however,

be a complete tetrahedron "outy tetrahedronshaped par-ts Vof it may be omitted.A For exam- 4 ple, one or several or allof the corners oi the .tetrahedron may be .cut away. It is preferable "to roundoi rthe edges of the tetrahedron by "a radius approximately equal to that of the. balls, since when sharp edges are used, passageways of a substantially larger area than between the balls are formed.

For a better understanding of the invention, reference may be had to the accompanying drawing, in which Fig. 1 is a perspective view of a set of balls arranged according to the invention;

Fig. 2 is a perspective view of one form of the homogenizing device, and

Fig. 3 is a side elevational view, partly in section, of another form of the device.

Referring to Fig. l, which illustrates the simplest arrangement of balls, the liquid flows from above through an opening I formed by three balls 2, 2a and 2b, positioned in an upper plane, into a chamber formed by the said three balls together with a fourth ball 3 in a lower plane. The balls are held in any suitable manner in the nested, intercontacting arrangement illustrated in Fig. 1, so that the liquid in flowing under the pump pressure through the ball set 2, 2a, l!b and 3 is confined to the paths indicated by the arrows in Fig. 1. It will be understood that the four balls of the set define an enlarged central space or whirl chamber to which the opening I forms an inlet passage. The liquid escapes from this whirl chamber through three outlet passages, each outlet passage 4 being formed by the lower ball 3 and two adjacent balls of the upper series`2, 2a and 2b. When the number of balls is increased, several parallel passageways of the same kind are formed and the Hows merge and separate again in each plane or series of balls.

As shown in Fig. 2, a largerk set of balls is arranged in a tetrahedron-shaped container 5, the interior of which hasrounded corners 6. The radius of eachrounded corner 6 is approximately equal to the radius of each ball l, so that the balls t closely into the corners. The balls 'I are held in position inthe container by a perforated member or grating 8. The direction of ow is assumed to be as indicated by the arrows, that is, upward from the bottom. Thus,'theinlet 9 is at the lower part and the outlet is through thegrating 8 at the top.

As shown in Fig. 3, a cylindrical container I is provided with a conical bottom I I and contains a set of balls I2 which are covered by a perforated member or netting I3 held against the balls by a ring I4 removably secured in the container. The liquid is assumed to flow upward from inlet I in the bottom of the container, the homogenized liquid finally discharging through the netting I 3- and the interior of ring I 4.

Depending upon the object of the homogenizing, a distinction must be made between'the atomizing eiect and the mixing eifect. When it is desired principally to atomize the particles or drops, it is best to utilize the available amount of pressure energy in a single step. It has been found preferable in practice, however, particularly when homogenizing milk, to use a certain number of steps (at least two steps), the nely atomized dispersed particles from the first step being eiciently mixed with the continuous phase in the last step or steps, so as to avoid the formation of agglomerates of particles sticking to the membrane scales which are easily formed in homogenizing. i

As mentioned with reference to Fig.g1, when the number of balls is increased, several parallel passagevvays are formed which run together and ramify again for each plane of balls. When an eilicient mixing action is desired in the homogenizing, a tube-shaped container, in which the direction of flow is in the longitudinal direction of the tube, should preferably be used. The balls should then be arranged in planes at right angles to the longitudinal direction of the tube. The longer the tube and the greater the number of ball planes, the higher the mixing effect will be.

It will be apparent that according to the present invention the milk or other liquid is forced through a Whirl chamber within a set of at least four intercontacting spheres (the balls 2, 2*, 2b and 3), the liquid being directed into the whirl chamber by way of an inlet passage (the passage I) dened by three of the spheres (the balls 2, 2'I and 2D) and being directed from the whirl chamber by way of a plurality of outlet passages (the passages v4) each defined by two of these three spheres and fourth sphere (the ball 3). The means for forcing the liquid through the interspaces of the ball set comprise the container (5, I Il) for the balls, and a pump I6 in the pipe line il leading tov the container inlet (9, I5).l

1. A device for homogenizing milk and other dispersions, which comprises a container having an inlet for the dispersion to be homogenized and an outlet for the homogenized dispersion, and a set of intercontacting balls in the container, the interspaces of the ball set forming ow path between said inlet and outlet. f

2. A device according to claim 1, in which the balls are of equal size.

3. A device according to claim 1, in which the ball set is in the form of a tetrahedron, whereby the set occupies the smallest possible volume in the container and the balls contact eachother at the largest possible number of points.

4. A device according to claim 1, in' which the container is in the general form of a tetrahedron.

5. A device according to claim 1, in which the container is in the general form of a tetrahedron, the interior of the container having corners rounded with a radius approximately equal to the radius of each ball.

6. A device according to claim 1, in which the container is cylindrical.

'7. A device according to'claim 1, in which the container is cylindrical and has a conical end wall in the interior thereof.

8. A device according to claim 1, in which the container is cylindrical and has a conical end wall in the interior thereof, said inlet being located in the conical end wall.

9. A device according to claim 1, comprising also a perforated member secured to the container for holding the balls in predetermined relative positions therein.

l0. A device according to claim 1, comprising 'also a perforated member secured to the con- CARL GRNNING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,666,640 I Cunniif Apr. 17, 1928

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