US2595376A - Device for stabilizing and homogenizing liquid mixtures - Google Patents

Description

y 1952 s. H. B. ZACHARIASSEN 2,595,376

DEVICE FOR STABILIZING AND HOMOGENIZING LIQUID MIXTURES Filed May 12, 1949 INVENTOR. 511'9 Q/o/ger @jame Zacharias-$622 :in the {homogenizing they can not therefore he 'used.

Patented May 6, 1952 DEVICE FORSTABILIZINGAN D H'OMOG- .IENIZING LIQUID iMIXTURES ZStigfHolgerLBjame Zachariass'n, Stockholm, Sweden, assignor to 'Aktiebolaget Separator, Stockholm, Sweden, a corporation of Sweden Application Mayl2, 1%l49,.;S.erial.N0.;92;774 LInQS-weden Mayi14,.19.48

.3 Claims. 1

This. invention relates to-a methodand-appara- 'itus for stabilizing and homogenizing .liguid mix- ".turespsuch asmilk.

IHomogenizi g -machines of the known types with maximum efficiency are so-called'high pressure homogenizers in which the liquid under treatment is forced'through very narrow slots under apressure ranging from'50 to 600 atmospheres. T e basic principle inall these machines Iis .tosubjectthe fator water-particles to be atomized .to such considerable deforming, when .they arepassing through .the narrow slot, that they are .divided intoa numberofsmallerparticles. As .the energy necessary Ifor generating themequisiteihigh pressure .can nothe recovered, homogenizing .machines of ithis t ne entail very :jhiigh. operating costs.

"Becauseof this, a great "number of .other con zstructions, ;so-called low pressure homogenizers, 1havefbeen.;devised; which work upon "very differ:

='.entj, rinciples and .in which the homogenizing is :efiectedflgmmeans .ofpressures between'll and ratmospheres. The power consumption .of these machines is, "of ,c;ourse. .correspon'ding'ly smaller,

but theirihomogenizing effect onthe whole-also correspondstbtheused pressure, so that. they can zgenerallybe :used only, for comparatively simple problems. "Whenihigh requirements mus'txhemet "Z'The homogenization of milk and :cream g re- =sents-ardifflcriltprob1em,ibecause inthis case "an "atomization .of the'fat globules "to maximum "2a and preferablyi r only, or'.less,1'is required. Heretofore it waspossible to'solvethis problem only'by. means of high pressure homogenizers operated by pressures of at least50"to 1'00 atmospheres. jI-Iomogenizing of'milk "has theref'ore not found "the prac'tical and jexten'siveuse .whichcould have been expected. I

Verycomprehensivetestshhoweverjhaveishown :that it ,is "possible to treat-milk and cream by means of considerably lower pressures and yet to obtain the :same final quality of the product: by

abandoning the principle onwhich'the high pressure homogenizers workand to im-part instead, in a first step,;a comparatively high velocity'to the liquid,'if"possible, without-losses and then'totreat Lit iii-such away,iin a-secon'd step,=tha t the velocity :is=conyerted,'atleastlargelyyintogpure liquidfri'ction atll'iighest -possible "turbulency' and avoiding,

"as fariaspos sible, 'any friction with thwsurrounding walls. r Tests have shown "that, when work- "ing on this-prin'ciple, average diametersof the fat 'g'lobules'ranging from '1 :1 to -13 can beobtained, when working with-pressuresof only 12 to 25stkept clean and'hygienic withless work.

- mospheres in the homogenizer, according totheinper cent is achieved. Furthermore, it is possible to dispense with the inletan'd-outlet valveswhich "complicate the useofhigh pressure' homogenizers, so thatgtaking everything into "account, a -'con- "structionisobtained which, whileihaving the'same efficiency, requires only a fraction oithe con- :sumption of materialran'd power of piston-pumps and is. 'zbesides, considerably simpler an d "cant-be According to the invention, the liquid'is supplied from-asource of pressure and-sprayed into aiclosed whirl-chamber in which'the velocity energy is converted, asfar as possible, into ,pure liquid friction. The dimensions of "the whirl- "chamber must be determined according "to "the material to be treated and to -prevailing "condiitions. The higher the pressure at *a certain "desired effect, the longer the whirl-chamber "must be, reckoned in the axial direction of the liquid jet issuing from the nozzle. -tancefrom the nozzle'are determinedby'thevls- Its-volume and "discosity of'the liquid to be treated. A general rule is that there should only be the'lowestpossible pressure, that is, a few atmospheres in the whirl- ;chamber or,iif theproperties of the'liquid make it-possiblea pressureapproac'hing n11. Ifin-the case of 'mil-k, for example, the homogenizing is considered satisfactory if no cream plugs "are formed within 48hours, a homogenizing device with-thefollowing data can be used: pressure 15- '30 kgs./cm'3 diameter of whirl-chamber 15-12 mms., length of whirl chamber 50-70'mms -dista-nce between outlet edge of'whirl-chamberand liquid outlet of nozzle greater than-'4"mms. "If,

for example, 12 per'zcent-creamiis homogenized by means of a higher -pressu refthe 'distancershould be greater, eventually as much 'as '2'0:mms; I'f a'still richer cream is-treated, the otl'rerdata-of the Whirl-chamber must also be changed-and-"cle- "termined according to-the viscosity.

The source of pressure 'may generally Eb screw pump or possibly a toothed-wheel or centrifugal pump. When particularly high requirements are put on the homogenized liquid and when, for onereason or other, the liquid must also be separated, the source of pressure is, according to the invention, the rotating bowl of a separator in which the entire homogenizing device is permanently fitted so that it also rotates. Depending upon the weight of the liquid and the diameter of the separator bowl and its velocity, there is in the outer layer of the bowl a pressure in the order of 30 to 60 atmospheres. After the liquid has passed through the homogenizing device, it discharges into the surrounding vessel so that, in addition to the homogenizing, also a qualitative control of the liquid with regard to particle size can be made in the separator. Fat and water particles of undesirable dimensions are separated in the bowl and fed to the homogenizing device for further treatment. Since the pressure of 30 to 60 atmospheres available in the separator bowl insures a very satisfactory atomization of the particles when homogenizing according to the invention, that part of the liquid flow which has been treated in the homogenizing device may generally be directly mixed with that part of the liquid flow which has passed through the separator.

If it is particularly important for the discharging liquid not to contain particles over a certain size, the liquid issuing from the homogenizing device is returned and mixed with the liquid fed to the separator. By this combination, which is especially advantageous for.mill and cream, only part of the whole quantity of the liquid is passed through the homogenizing device,

which may be made correspondingly smaller. ..With a view to avoiding admixture of air, the

receiving vessels of the separator should preferably be kept under vacuum. The effect of the described device may be improved by forcing the liquid out of the nozzle not only with an axial velocity but also with a rotative motion imparted to it in advance of the nozzle by feeding it in a tangential direction into its antechamber. In this manner the velocity gradient is also increased, especially in the whirl-chambers, and the result of the homogenizingis improved. The result of the homogenizing is generally improved'as the turbulent motion. in the whirl-chamber is increased. Consequently, the result may be improved by providingparts in the whirl-chamber which cause strong turbulence. These parts may, for example, consist of chips or bodies of other shape which are particularly disadvantageous from a flow standpoint, that is to say, are provided with sharp corners, edges, etc. at which whirls are formed. Since such parts can not be kept sufficiently clean, they preferably consist of a single unit which, after completion of the work, can be thrown away and replaced bya new one.

The accompanying drawing shows by way of example some embodiments of the invention.

Fig. l is a schematic view illustrating the basic principle of the invention;

Fig. 2 is a similar view, but'in greater detail, illustrating the practical construction of an ap paratus of this type;

-Figs. 3 and 4 are diagrammatic illustrations of a cyclone for increasing the velocity gradient by introducing the liquid tangentially into the apparatus, and

Fig. 5 is a vertical sectional view of a cen- I trifugal separator bowl provided with an homog- 4 enizing device in accordance with the invention.

The liquid is fed from a nozzle I into a whirlchamber 2 in which the conversion of velocity energy into liquid friction takes place, any friction against the surrounding walls of the bowlchamber 2 thereby being as far as possible avoided. As shown in Fig. 2, the nozzle 3 is movable in an axial direction in a sleeve 4, so that the distance between the liquid outlet of the nozzle and the outlet edge of the whirl-chamber 5 can be adjusted by a movable part 6. A manometer 1 is used for controlling the pressure in the whirl-chamber. Figs. 3 and 4 show the use of a cyclone 8 for increasing the velocity gradient by introducing the liquid tangentially into the chamber 2 (with a rotating motion about the axis of the chamber). Referring to Fig. 5, from a liquid, which may be fed into the bowl I0 through the hollow spindle or inlet 9, that part which contains fat and water particles of comparatively large diameters is separated in the separating chamber between the discs ll, according to the type of emulsion under treatment. According to the type of emulsion being treatedwater in oil or oil in water-the outer (heavier) or the inner (lighter) phase in the separator bowl is led to the homogenizing device I3 for further treatment. From the homogenizing device the liquid flows into the collecting vessel l2, whence it either proceeds to that part which has passed directly through the separator or is remixed with the liquid to be fed to the separator.

In the whirl-chamber 2 (or 5), which may be stationary, the liquid discharged at high velocity from nozzle l (or,3) is caused to undergo-a whirling motion before it is discharged over the periphery of the whirl-chamber at its open end, as shown by the arrows in Figs. 1 and 2, whereby the liquid velocity is rapidly converted at least largely into liquid friction. It will be understood that when the cyclone 8 is employed to increase the velocity gradient, the cyclone gives the liquid a rotating motion as it passes through the nozzle into the Whirl-chamber, as. shown by the arrow in Fig. 4. When the homogenizing device is incorporated in a centrifugal separator bowl, as shown in Fig. 5, the homogenizer I3 is essentially the same as those shown in Figs. 1 and 2, inthat it has a'nozzle for bringing the liquid particles to high velocity, and a whirl-chamber for receiving the nozzle discharge and rapidly converting the liquid velocity (radial) largely into liquid friction before it is discharged into the stationary collecting vessel l2, which preferably kept under vacuum by suitable means (not shown). As illustrated in Fig. 5, the larger particles of the liquid are separated as a lighter component and pass from the central part of the bowl outward through a bottom passage to the nozzle which opens into the whirl-chamber l3 of the homogenizer, the homogenizer being shown only generally in Fig. 5. The heavier liquid from which the larger particles are separted in the bowl passes upwardly under the bowl top and is discharged separately.

I claim:

1. A device for stabilizing and homogenizing liquid mixtures, which comprises a centrifugal separatorbowl having an inlet for the liquid and a separating chamber communicating with the inlet, a nozzle in the bowl for receiving the municating with the nozzle for rapidly converting the liquid velocity of said particles at least largely into liquid friction with substantial turbulence, to homogenize the mixture of said particles, and a stationary vessel surrounding the bowl for receiving the homogenized particles from the whirl-chamber.

2. Apparatus for stabilizing and homogenizing emulsions, which comprises a centrifugal bowlhaving a separating chamber for centrifugally separating the emulsion into homogenized and non-homogenized components, the bowl having an outlet for the separated homogenized component, an homogenizing device at the peripheral part of the bowl and having an outlet for a second homogenized component, and means in the bowl for conducting said non-homogenized component from the separating chamber to said homogenizing device.

3. Apparatus according to claim 2, in which the homogenizing device includes a whirl-chamber through which the non-homogenized component passes from said conducting means to said second outlet, the whirl-chamber being adapted to effect rapid conversion of the velocity of said last component at least largely into liquid friction with substantial turbulence.

STIG HOLGER BJARNE ZACHARIASSEN.

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

UNITED STATES PATENTS Number Name Date 336,324 Johansson Feb. 16, 1886 439,173 Newberry et al. Oct. 28, 1890 1,406,791 Werner Feb. 14, 1922 1,846,076 Anderson Feb. 23, 1932 1,866,638 Fawcett July 12, 1932 1,925,049 Howard Aug. 29, 1933 2,060,239 Peltzer Nov. 10, 1936 FOREIGN PATENTS Number Country Date 539,016 France June 19, 1922 584.860 Germany Sept. 25, 1933

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