Improved Method of and Apparatus for Extracting Fatty Particles from Emulsions.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improved Method of and Apparatus for Extracting Fatty Particles
from Emulsions.
I, CARL DIDRIK HELLSTRÖM, of Sala, in the Kingdom of Sweden, Engineer,
do hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
In fatty emulsions, wherein fat globules of different sizes occur, such as is for
instance the case in milk, the completeness of the extraction of fat depends chiefly
on the quantity of the smaller fat globules which are separated.
The rapid and complete separation of cream from milk obtained by the Schwarz
method is considered to be owing to a circulation taking place in the milk, the
larger fat globules as they pass towards the surface, carrying with them a portion
of the smaller ones which do not possess any floating power, and would not there-
fore be otherwise separated.
The present invention relates to a method in which a similar result is produced
in the separation of fat from an emulsion by means of centrifugal force. By
arranging in a centrifugal apparatus a disc or ring which is provided with corruga-
tions concentric with the axis, the fatty particles will collect upon the parts of the
corrugations turned from the.axis outwards, and the particles of serum on the parts
turned towards the axis. The fatty particles will thereby be obstructed in their
passage until a layer or bed is formed which entirely covers this part. of the
corrugations. This layer is now partly merged into a liquid which is poorer in fat
and therefore heavier whereby both the floating power of the layer and the
separating effect of the centrifugal force are increased so that the layer is pushed
off from the base of the corrugations towards the top nearer the axis. From the
surrounding emulsion more fatty particles are continually separated so that the
movement of the layers toward the top is continuous.
The layer of serum collected on the part of the corrugation turned towards the
axis is subjected to a pressure caused in a similar manner, urging the serum toward
the top of a corrugation further from the axis.
From each of the tops of the concentric corrugations a layer rich in fat moving
inward meets a layer of serum poorer in fat moving outward, so that these layers
penetrate each other whereby the smaller fat-globules existing in the layer of serum
come into contact with the larger fat globules moving inward. The carrying force of
the latter globules has been materially increased owing to the accumulations caused by
the
pressure exerted by them against each other and against the corrugations.
If now another disc or ring corrugated in the same way is caused to approach
the first disc or ring in such a manner that the protruding parts of the latter extend
into the receding parts of the former, the effect of the arrangement will be con-
siderably increased, because the emulsion in the intermediate space deposits its fatty
particles on the corrugations more rapidly and the remaining liquid, into which
the layer which is richer in fat is merged becomes heavier and the effect of the
centrifugal force consequently greater. The layer which is richer in fat, coming from
a top situated farther from the axis now settles on the next corrugation and thus
facilitates the movement of the layer which arrived there before, towards the
next top.
In the free space nearest the surface of the rotating liquid a similar action of the
larger fat globules and accumulations upon the smaller ones takes place. The
emulsion passing through the inlet-tube into the centrifugal apparatus is mixed
together with the layer which is richer in fat and lies on the surface, and with the
currents which are richer in fat and come from each intermediate space. The

page_text: tendency of the centrifugal force to throw out the entering emulsion which is
heavier than the liquid in the free space even with the lower intermediate spaces is
thus counteracted.
The accompanying drawing shows a centrifugal cream separator arranged
according to the present invention.
Figure 1 is a vertical section of the apparatus and
Figure 2 is a horizontal section of the same.
C
The apparatus comprises a centrifugal vessel a, closed by a cover b which is
easily removable. The inlet-tube c for the milk is arranged centrally and provided
with four vanes d. Outside these vanes annular discs or rings with concentric
corrugations having sharp edges e or rounded edges el are provided one above the
other in such a way that the projections of a lower disc or ring extend into
the depression of the next disc or ring above.
The left hand side of Figure 1 illustrates as an instance discs or rings with
concentric corrugations having sharp edges e while the right hand side represents
discs or rings with corrugations having rounded edges . The discs or rings are
kept at a suitable distance from each other by metallic pieces secured by solder or
by projections stamped out of the plate, and do not reach the casing of the vessel.
Hence an annular space is formed in which the separated heavier liquid (the milk)
collects and may be led off in the ordinary way through a skim-tube. f. The
lighter liquid (the cream) is carried away by another pipe g.
By experiment it has been proved that a comparatively good result is attained
by the employment of discs or rings the diameter of which is considerably smaller
than that of the vessel, and which consequently reach only a short distance into the
rotating liquid. In this case the discs or rings form a grating concentric with
the axis.
.
If the space between two discs or rings be divided into sections by diametrical
planes the action, within each section of the intermediate space is similar to that
described above. This is the case if the surfaces of the corrugations are not
rotating surfaces.
The chief feature of this invention is however that the liquid to be separated is
caused, in the manner above described and illustrated in the drawing by means of
discs or rings of suitable cross-section to traverse a broken or undulatory path.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:
First. The method of effecting, in centrifugal apparatus, a more rapid and
complete separation of fat from emulsions for instance from milk which consists in
causing the emulsion to be separated, to pass between discs or rings arranged in the
centrifugal apparatus in such a manner that the emulsion on its way through
the intermediate spaces between the discs or rings to the casing of the vessel shall
take a broken or undulatory path.
Second. In centrifugal apparatus for carrying out the method characterized in
the first claim the arrangement of discs or rings having concentric corrugations one
above the other substantially as hereinbefore described.
Dated this 15th day of October 1801
HASELTINE; LAKE & Co.,.-
_
45, Southampton Buildings, London, W.C., Agents for the Applicant.