An Improved Process for Separating Cream from Milk, and Apparatus therefor.
Year: 1895

page_text: Date of Application, 16th May, 1895-Accepted, 27th July, 1895
COMPLETE
SPECIFICATION.
An Improved Process for Separating Cream from Milk, and
Apparatus therefor.
I, OLAF OHLSSON, of Newark, in the County of Essex and State of New Jersey,
United States of America, Machinist, 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 :-
Heretofore in the centrifugal creaming of milk various methods and devices
have been invented (and some of them have been used in the art) to increase the
skimming capacity and coincidently the closeness of the skimming for a given
expenditure of power. To this end it has latterly been common to divide the milk
occupying the liquid space of the bowl into numerous thin layers, laminæ or strata
obliquely crossing the radial lines of the bowl (in which thin layers, laminæ or
strata simultaneous but independent separation goes on) the separated cream from
each of the thin layers moving directly and through an unobstructed central flow
passage to the common cream outlet of the machine and the separated blue milk
from each of the layers moving directly and through an unobstructed peripheral flow
passage to the common blue milk outlet of the machine. It has also been
suggested to guide the main milk body successively through a number of interior
bowl chambers of various shapes, thereby retaining the milk longer in the bowl
subject to the centrifugal action and at the same time subjecting the milk to that
action in smaller individual bodies or masses. In all of these cases it is centrifugal
action alone that is relied upon to accomplish the separation.
I have discovered that while simple centrifugal action is efficient to economically
separate out from full milk into the form of cream a large proportion of the fat
particles that the full milk contains, say ninety per cent. of those fat particles, yet
it is not when used alone efficient to economically separate out the residual
ten per cent.; and that in ordinary practice the separating out or skimming of the
last ten per cent. of the fat particles actually delays and retards the whole
separation to such a remarkable extent that the capacity for a given expenditure
of power is reduced by attempting to take out the last ten per cent. almost one
half. Thus a bowl which at normal rotative speed will skim 600 pounds of full
milk per hour, leaving ten per cent. of the fat in the blue milk will at the same
rotative speed skim only 300 to 350 pounds of full milk per hour, if the skimming
is made approximately clean. That is to say, with the continuous expenditure of
the same power froni minute to minute it will take almost twice as long to skim
the 600 pounds approximately clean as it takes to skim it up to ninety per cent. of its
fat particles. Or, in other words, with the machine running at the same speed the
rate of inflow of full milk which is permissible when skimming only ninety per cent.
of the fat particles must be reduced almost one-half when it is desired to also skim
the residual ten per cent. or approximately so. I do not intend these figures as
exact measurements, but they will serve to illustrate what is the fact, that
enormous sacrifices in capacity are involved in forcing up even to a small extent
the last percentages of fat particles that are separated or skimmed by a given
machine, and I believe this to apply generally to all existing centrifugal
machines.
I have further discovered that this characteristic of existing creaming methods
and devices is due to a difference (as I conclude, in size or weight) in the fat
particles themselves, the great majority of the fat particles in ordinary full milk
being of such a character as to readily Hoat out or separate out from the blue milk

page_text: under intense centrifugal action while a small percentage, as say ten per cent. or
thereabouts, of the fat particles are of such a character as to be separated (even by
the most intense centrifugal force) only with great difficulty and slowly from the
blue milk. If it. is a matter of the relative size of the fat particles, as seems to be
indicated by the phenomena observed, it is readily explicable. For the larger
particles will, simply because of their greater size, be more pointedly contrasted in
gravity or weight with blue milk particles or masses of equal size and so the two
will respond to the centrifugal action with sufficient difference to separate them
readily from each other, whereas the small fat particles may be so small that the
difference between their gravity or weight and that of a blue milk particle or
mass of equal size is not enough to bring about their separation except slowly.
Moreover the forces of adhesion or cohesion may hold the small fat particles more
tightly to the small particles of blue milk or serum than they hold the large fat
particles to the large particles of blue milk. On the other hand the less readily
floatable or separable particles or some of them inay he less readily floatable or
separable because of some peculiarity in the molecular intermixture or entrapping
of those fat particles in or with the blue milk particles, or of the latter in or with the
former, making, for instance, perhaps sponge-like masses of the fat particles greater
in specific gravity as masses by reason of the blue milk entrapped in them
than more concentrated masses of those same fat particles would be. I have
further discovered that the separation by centrifugal action of these small or less
readily floatable or separable particles of fat may be greatly facilitated, and that
this can be brought about simultaneously with the continuous separation of the
larger or more readily floatable or separable fat particles, the whole resulting in a
centrifugal creaming or skimming of the full milk that is practically clean or
complete and that is attained with a sustained capacity approximately equalling
that with which existing machines and methods separate the larger or more readily
floatable or separable fat particles, that is to say, when they leave ten per cent.,
more or less, of the fat in the blue milk. Thus in the case supposed above, the
bowl whose normal capacity when skimming the fat approximately clean was 300
to 350 pounds and when skimming ninety per cent. of the fat was 600 pounds would
when employed so as to utilize and embody my discovery have a capacity of
600 pounds when skimming clean, and the skimming would be cleaner than in the
first case.
This extraordinary result I have attained by the use of the method
herein set out and claimed, and by the use of appropriate apparatus carrying out
the said method.
My invention consists of the method or process and of the apparatus herein set
out and claimed.
The method or process involves, speaking generally, three steps, namely, first, a
preliminary separation of the full milk in any desired form of separating chamber
or chambers, this separation being attained by centrifugal action in any ordinary
way and accomplishing, for the reasons set out above, the separation of the larger
or more readily floatable or separable fat particles from the milk, the lighter and
heavier products of this separation being conducted apart; secondly, an agitating
of the partially skimmed milk, resulting, as I believe, in a coalescing or con-
centrating of the finer or less readily floatable or separable fat particles that
remain in the separated blue milk as it comes from the first step of the process,
into larger or more readily floatable or separable fat particles; and thirdly, a final
separation of the liquid as it comes from the second step of the process in any
desired form of separating chamber or chambers and a conducting apart of the.
lighter and heavier separated ingredients. The cream resulting from the preliminary
separation and that resulting from the final separation may be mingled together
and delivered together from the apparatus or they may be separately delivered as
desired.
In the first step of the process-the preliminary separation-any centrifugal
process of separating cream from milk may be employed which continuously
delivers the separated ingredients apart. It is the purpose of this step of the

page_text: process to separate out the larger or more readily separable fat particles; and the
full milk can be fed into the apparatus at such a rate of speed as results in the
separation in this first step of the process of only such larger or more readily
separable fat particles.
In the second step of the process-the agitating of the partially skimmed milk,
involving probably the coalescing or concentrating of the finer or less readily
floatable or separable fat particles retained in the heavier ingredient as it comes
from the first step of the process into larger or lighter or more readily floatable or
separable particles-any effective means of doing the work may be employed.
I have found it effective to agitate the heavier ingredient, as it comes from the
first step of the process, by forcing it while still under the influence of intense
centrifugal action into repeated collisions with itself, training it into zigzag courses
near the periphery of the bowl with diverging and converging currents and without
opportunity for either its blue milk or its cream to permanently separate and escape
apart, but forcing all to pursue together the same obstructed paths. I therefore
prefer this particular method of carrying out the second step of my general process,
although I do not wish to be limited to it in my broad claims for the general
process. This second step of the general process may be carried out by apparatus
of such capacity and under such conditions that the separated heavier ingredient
resulting from the first step of the process is treated as rapidly as it is delivered
from said first step, whereby the full rate of work or full capacity of the method
or apparatus by which the first step is accomplished may be availed of continuously.
An effective way of attaining this end is illustrated in the special form of apparatus
shown in the drawings and described below.
The third step of the general process is intended to avail of the results achieved
in the second step, that is to say, the centrifugal force now acts upon the liquid as
it comes from the second step of the process under such conditions as to permit the
separation of the now larger or more readily separable fat particles from the skim
milk and their permanent segregation apart and their separate delivery from the
apparatus. For this step any desired method or form of apparatus for the
centrifugal creaming of milk may be employed. It should be of such capacity as
to readily receive and dispose of the continuous stream of liquid, consisting of blue
milk and of coalesced or concentrated or more readily floatable or separable fat
particles, that comes from the second step of the general process.
Some convenient and effective forms of apparatus for carrying out my general
process and invention in its preferred form are shown in the drawings, in which
Figure 1 is a central vertical section of a separating bowl and coöperating
parts;
Figure 2 is a horizontal section of the upper portion of the cover of the same ;
Figure 3 is a vertical section of the same;
Figure 4 is a horizontal section taken through the body of the bowl of
Figure 1;
Figure 5 is an illustrative detail of a modification; and
Figure 6 is a detail of the bowl of Figures 1 to 4.
a is a rotary shaft carrying the bowl b, and is driven by any suitable driving
mechanism, which bowl has a cover c. e and d constitute the inlet for full milk,
which milk is subjected to centrifugal force in the separating chamber f, being kept
in rotation by wing f¹.
Within the bowl b is a second and inner bowl d concentric therewith, and,
throughout the greater part of its height, closely adjacent at its outer periphery to
the inner wall of the bowl b, at a uniform distance of say one-eighth of an inch
more or less in a bowl of the diameter of four or five inches, forming a thin
peripheral annular chamber d, the agitating chamber. The inner bowl d carries
or is carried by the full milk inlet e and d" and the three parts are carried by the
bowl b. The bowl d is open at the bottom as shown and above it and outside of it
but within the bowl 6 and its cover c is the final separating chamber g, having
wing a¹ to compel rotation. The bowl has a cream delivery m' and the bowl b

page_text: and its cover c have a cream delivery i regulated by a screw j, cut away at j¹, and
a blue milk outlet . In the thin peripheral agitating chamber d between the
outer and inner bowls where they are closely adjacent to each other are arranged
close groups of pins d¹ forming obstructions, the groups being staggered with
respect to each other and having narrow spaces d'11 between the groups as shown
in Figure 6 which is a face view of a number of such groups. The pins or
obstructions extend radially outward from the wall of the inner bowl to the wall of
the outer bowl. m is the general cream wall of the apparatus as a whole. In place
of the groups of pins d' of Figures 1 and 4 might be substituted other obstructions
such as radial plates or ribs of various kinds extending from the outer wall of the
inner bowl to the inner wall of the outer bowl and with openings so placed as to
avoid direct flow passages for either blue milk or cream. Fig. 5 shows V-shaped
ribs overlapping each other in reverse and the arrows indicate the enforced tortuous
movements and the diverging and converging currents of the liquid as it works
up through the agitating chamber d toward the final separating chamber g.
The process as it would be practiced in the particular apparatus of the drawings
is as follows:
The
It
The full milk is introduced continuously in a properly regulated manner through
the inlet e and into the separating chamber f, where separation of the more readily
separable fat particles takes place under the influence of centrifugal force.
speed of inflow of the full milk into this separating chamber fis by my process
permitted to be so rapid that only the larger or more readily floatable or separable
fat particles are separated in this separating chamber f, these fat particles gathering
as a cream wall along the line m and continuously discharging through the cream
discharge m¹, the smaller or less readily Hoatable or separable fat particles
remaining in the partially skimmed milk which continuously discharges underneath
the lower peripheral edge of the inner bowl d. This ends the first step of the
process. The partially skimmed milk discharged from the separating chamber f
now moves upward in the thin peripheral agitating chamber d¹. In this movement
it does not find direct flow passages to facilitate the same but on the contrary it
meets with obstructions to its direct flow and is forced thereby into tortuous
windings and is divided into currents that collide and divide and collide again.
does not find quiescent pockets from which separated fat particles are discharged
apart from the blue milk, but on the contrary the conditions are such that the only
escape for the fat particles is by being swept along with the blue milk, which
sweeping along involves repeated collisions of these fat particles with each other
and agitation of the liquid mass resulting, as seems probable, in the gradual
coalescence or concentration of these fat particles into larger or more readily
floatable or separable particles. To the extent that the cream particles separate
(if they separate at all) in this agitating chamber d under the intense centrifugal
action there proceeding they gather against and among the obstructions and in
eddies behind the obstructions and there become targets for the bombardment of
the blue milk particles and of the fat particles carried along by the blue milk
current and they are ultimately borne along on the general current, having no other
way of escape. The obstructions and passage ways are preferably so arranged as
to produce the maximum of mechanical collisions and agitations (and so, as seems
probable, of coalescence or concentration) of the fat particles consistent with the
required rapid movement and escape of the general body of liquid. This ends the
second step of the process. The liquid is now delivered into the final separating
chamber g, where it now readily separates into its lighter and heavier ingredients,
the fat particles which resisted the separating action of the centrifugal force in the
preliminary separating chamber f readily yielding to it in the final separating
chamber g, and this because of the effect upon them of the agitation, and so of the
coalescing or concentrating or lightening action of the second step of the process.
The separated cream gathers near the center of the chamber g, unites with the
body of cream rising from chamber through m' and the discharge is at i. The
separated blue milk is discharged through the outlet conduit h.

page_text: The broad invention is irrespective of any particular apparatus and may be
carried out and embodied in many different forms of apparatus. For instance, in
place of the preliminary separating bowl or chamber f any other kind of separating
bowl or chamber may be used, as for example one with numerous partitions and
numerous thin milk layers, like the so-called Alpha bowls, or any other form of
bowl might be used, either any bowl that is known now or any bowl that may
hereafter be invented, provided its operation is to separate full milk by centrifugal
action and deliver the separated ingredients apart and further provided its
operation is not inconsistent with the other steps of my process. The same thing
practically is true also of the final separating chamber g. The agitating chamber dui
may also be very greatly varied in form or character without departing from the
invention. It is only necessary that the escaping heavier ingredient as it comes
from the first step of the process shall be mechanically agitated sufficiently to
substantially coalesce or concentrate or lighten or otherwise prepare the small or
less readily floatable and separable fat particles that it contains into larger or more
readily floatable or separable fat particles, so that they shall in the third step of
the process yield to the separating action of centrifugal force which they resisted
in the first step of the process.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. The herein described process of creaming milk which consists in first
separating the more readily separable fat particles by centrifugal action, then
agitating the partially skimmed milk whereby the fat particles contained in such
partially skimmed milk are prepared for the final separation, and finally separating
these fat particles from the skim milk by centrifugal action.
2. The herein described process of creaming milk which consists in first
separating the more readily separable fat particles by centrifugal action, then
agitating the partially skimmed milk while under centrifugal action whereby the
fat particles contained in such partially skimmed milk are prepared for the final
separation, and finally separating these fat particles from the skim milk by
centrifugal action.
3. The herein described process of creaming milk which consists in first
separating the more readily separable fat particles by centrifugal action, then
agitating the partially skimmed milk while under centrifugal action by dividing
the same into diverging and converging currents whereby the fat particles contained
in such partially skimmed milk are prepared for the final separation, and finally
separating these fat particles from the skim milk by centrifugal action.
4. The herein described process of creaming milk which consists in first
separating the more readily separable fat particles by centrifugal action, then
agitating the partially skimmed milk while under centrifugal action by dividing
the same into diverging and converging currents whereby the fat particles contained
in such partially skimmed milk are prepared for the final separation, and finally
separating these fat particles from the skim milk by centrifugal action and
discharging together the fat particles resulting from the two separations.
5. A centrifugal separator, substantially as set forth, comprising a preliminary
centrifugal separating chamber in which the full milk is subjected to a preliminary
separation, an agitating chamber which receives the partially skimmed milk from
the preliminary chamber and prepares the fat particles contained in such partially
skimmed milk for the final separation, and a final centrifugal separating chamber
which receives the liquid from the agitating chamber and in which the fat particles
contained in such liquid are separated from the skim milk.
6. A centrifugal separator, substantially as set forth, comprising a preliminary
centrifugal separating chamber in which the full milk is subjected to a preliminary
separation, a centrifugal agitating chamber which receives the partially skimmed
milk from the preliminary chamber and prepares the fat particles contained in such

page_text: partially skimmed milk for the final separation, and a final centrifugal separating
chamber which receives the liquid from the agitating chamber and in which the fat
particles contained in such liquid are separated from the skim milk.
7. A centrifugal separator substantially as set forth, comprising a preliminary
centrifugal separating chamber in which the full milk is subjected to a preliminary
separation, an agitating chamber which receives the partially skimmed milk from
the preliminary chamber and which is provided with obstructions whereby such
partially skimmed milk is divided into diverging and converging currents, and a
final centrifugal separating chamber which receives the liquid from the agitating
chamber and in which the fat particles contained in such liquid are separated from
the skim milk.
8. A centrifugal separator substantially as set forth, comprising a preliminary
centrifugal separating chamber in which the full milk is subjected to a preliminary
separation, a centrifugal agitating chamber which receives the partially skimmed
milk from the preliminary chamber and which is provided with obstructions
whereby such partially skimmed milk is divided into diverging and converging
currents, and a final centrifugal separating chamber which receives the liquid from
the agitating chamber and in which the fat particles contained in such liquid are
separated from the skim milk.
9. A centrifugal creaming bowl having suitable inlet and outlet conduits and
suitable driving mechanism, and provided with a preliminary separating chamber
in which the full milk is subjected to a preliminary separation, an agitating
chamber which receives the partially skimmed milk from the preliminary chamber
and prepares the fat particles contained in such partially skimmed milk for the
final separation, and a final separating chamber which receives the liquid from the
agitating chamber and in which the fat particles contained in such liquid are
separated from the skim milk, substantially as shown and described.
10. A centrifugal creaming bowl having suitable inlet and outlet conduits and
suitable driving mechanism, and provided with a preliminary separating chamber
in which the full milk is subjected to a preliminary separation, an agitating
chamber which receives the partially skimmed milk from the preliminary chamber
and which is provided with obstructions whereby such partially skimmed milk is
divided into diverging and converging currents, and a final separating chamber
which receives the liquid from the agitating chamber and in which the fat particles
contained in such liquid are separated from the skim milk, substantially as shown
and described.
11. A centrifugal creaming bowl having suitable inlet and outlet conduits and
suitable driving mechanism, and provided with a preliminary separating chamber
in which the full milk is subjected to a preliminary separation, a peripheral
agitating chamber which receives the partially skimmed milk from the preliminary
chamber and prepares the fat particles contained in such partially skimmed milk
for the final separation, and a final separating chamber which receives the liquid
from the agitating chamber and in which the fat particles contained in such liquid
are separated from the skim milk, substantially as shown and described.
12. A centrifugal creaming bowl having suitable inlet and outlet conduits and
suitable driving mechanism, and provided with a preliminary separating chamber
in which the full milk is subjected to a preliminary separation, a peripheral
agitating chamber which receives the partially skimmed milk from the preliminary
chamber and which is provided with obstructions whereby such partially skimmed
milk is divided into diverging and converging currents, and a final separating
chamber which receives the liquid from the agitating chamber and in which the
fat particles contained in such liquid are separated from the skim milk, substantially
as shown and described.
13. A centrifugal creaming bowl having suitable inlet and outlet conduits and
suitable driving mechanism, and provided with a preliminary separating chamber
in which the full milk is subjected to a preliminary separation, a thin peripheral
agitating chamber which receives the partially skimmed milk from the preliminary

page_text: chamber and prepares the fat particles contained in such partially skimmed milk
for the final separation, and a final separating chamber which receives the liquid
from the agitating chamber and in which the fat particles contained in such liquid
are separated from the skim milk, substantially as shown and described.
14. A centrifugal creaming bowl having suitable inlet and outlet conduits and
suitable driving mechanism, and provided with a preliminary separating chamber
in which the full milk is subjected to a preliminary separation, a thin peripheral
agitating chamber which receives the partially skimmed milk from the preliminary
chamber and which is provided with obstructions whereby such partially skimmed
milk is divided into diverging and converging currents, and a final separating
chamber which receives the liquid from the agitating chamber and in which the fat
particles contained in such liquid are separated from the skim milk, substantially
as shown and described.
15. The bowl b having suitable inlet and outlet conduits and driving mechanisin,
in combination with the interior concentric bowl d forming an annular chamber d¹¹
provided with obstructions d', substantially as and for the purposes set forth.
Dated this 16th day of May 1805
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.