Improvements in Centrifugal Separating Machines.
Year: 1897

page_text: CUMI LEIM
DIEVITICATION.
Improvements in Centrifugal Separating Machines.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by Phillp M. Sharples, of West Chester, in the
County of Chester, State of Pennsylvania, one of the United States of America,
Manufacturer of Dairy Supplies) and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement :-
The object of this invention is to provide a centrifugal separating machine in
which a centrifugal force is developed which is much greater than has been hitherto
attained in such machines and in which the frictional resistance to the separation of
the lighter from the heavier particles of liquid treated is very greatly reduced, the
bearings for the support of the revolving bowl being such as will insure durability,
freedom from jar and friction, and improved lubrication.
Figure 1 is a vertical section, partly in elevation, of a centrifugal separating
apparatus constructed in accordance with this invention;
Figure 2 is a view on a larger scale, of the upper portion of the separator bowl;
Figure 3 is an enlarged sectional plan the section being taken on the line x,
Figure 2;
Figure 4 is an enlarged section of the lower portion of the bowl and its casing, and
of the lower bearing;
Figure 5 is a view of the lower portion of the bowl and casing partly in section,
but mainly in elevation to illustrate one means which may be employed for imparting
rotation to the bowl;
Figure 6 is a sectional view illustrating the application of one feature of my
invention to a different form of bowl from that represented in Figure 1; and
Figure 7 is a sectional view of the lower portion of the bowl representing another
modification.
In
The fixed fraine of the separator inay be constructed in any desirable manner.
the construction shewn in the drawings the frame 1 surrounds the separator bowl 3
and has a depending portion 2 carrying the lower bearing for the said bowl, and an
upwardly projecting and overhanging arm 4 carrying the upper bearing.
The bowl has at the bottom a projecting neck 5 with inturned bottom, and the
passage within this neck communicates with the interior of the bowl, through
openings 5 in the bottom of the said bowl. A projection extends upwardly into
the bowl from the bottom thereof and has a central opening for the reception of the
tapered upper end 6 of the supporting spindle of the bowl, the said spindle being
reduced in diameter between its upper and lower ends so as to form a flexible, or
elastic, shank 7, the lower portion of the spindle constituting a bearing 8, partly
cylindrical, and partly tapered, and terminating in a rounded lower end which rests
upon a ball 9 free to turn on a disc or washer 10, mounted upon a spring 11, in a
perforated cup 12, which is screwed into the lower end of a sleeve 13, carried by a
depending portion of the fixed casing, a lock nut 14 serving to secure the said sleeve
11

page_text: in position after adjustment. The greater part of the weight of the bowl and its
load is borne by the ball 9 and the elastic support of the latter, the spindle being
retained in its proper lateral position by means of balls 15 bearing against the
tapered sides of the lower portion 8 of the spindle and resting upon a washer 16
which is supported upon a spring 17 surrounding the cup 12, as shown in Figure 4,
a flanged and hardened bushing 18 serving to retain the balls 15 in proper lateral
position.
By the use of the laterally flexible, or elastic, spindle 7 a certain limited amount
of vibration of the bowl is permitted, slight vertical movement of the bowl being
also provided for by the elastic support of the bearing roller 9, these features being
found to aid in the successful running at very high speed of a bowl of the character
described.
A depending hood 7" surrounds the spindle 7, and serves to limit the vibration of
the bowl due to the lateral flexibility of the said spindle.
The driving of the bowl is effected by means of a jet of steam, or other motive
fluid, under pressure, emerging from an inclined nozzle 20 Fig. in the base of the
fixed casing, this jet impinging upon the buckets 21 formed in a projecting flange
at the base of the bowl. The invention is not limited to this method of driving the
bowl, as it may be driven by belts and pulleys, gearing, or in any other way, whereby
the desired high speed of rotation can be attained.
The bowl has, at the upper end, a tapering cap 22 with upwardly projecting
tubular spindle, or stem, 23, in which are formed an outlet 24 for the heavier portion
of the separated liquid, and, at a lower point, a vertical groove, or channel, 25, for
the escape of the lighter portion of the liquid, the flow from the said channel 25 being
around the inner end of a set screw 26 which obstructs the groove, as shewn in 2
Figure 6ª, hence by adjustment of this set screw, the escape of the cream or the like
is regulated in the usual manner.
In the upper portion of the tubular spindle 23 is another outlet 27 for a purpose
hereinafter stated.
The upwardly projecting tubular stem, or spindle, 23, has a bearing against the
inner ends of knots, or tufts, of bristles, fibres, or other flexible material, 30, carried
by annular blocks 31 which are contained in a pocket, or cup, 28, at the upper end
of the arin 4, a cap 29 screwing into the upper end of the cup and serving to retain
the annular blocks 31 therein.
The extremely high speed which it is desirable to attain in this separator renders 3
it inadvisable to use the usual metal contact bearing, owing to the fact that in practice
the spindle is frequently liable to run slightly out of truth, and in this case the
immensely rapid vibrations of metal surfaces against each other will immediately
cause abrasion and cut out the bearing. The bowl, when rotating is disposed to stand
upright and revolve upon the axis of its mass after the manner of a top, with no 4
inherent tendency to set up any vibratory, or irregular motion, hence my foreign
correspondent has devised the bearing shewn in Figures 1, 2 and 3, which by a
slight and yielding pressure, serves to overcome any vibratory motions of the bowl
that may be set up by atmospheric, or other outside, disturbances. The bearing is
preferably composed of bristles, or fibres, presenting their ends to the journal 4
of the bowl, as shewn in Figure 3, but other elastic materials may be used, the
essential requirement being that of a yielding contact which offers small inertial
resistance.
The liquid to be separated is delivered to the machine from a bowl, or hopper, 32,
which communicates through a pipe 33 with the interior of the sleeve 13 which 5
contains the lower bearing for the bowl, 3 hence the liquid rises through this bearing
and serves to lubricate it before entering the chamber 34 above the bearing, from
which chamber the liquid is drawn through the casing and openings 5°.
The improved separator while applicable for the separation of any liquid bodies
composed of constituents having different specific gravities, is intended mainly for 5
the separation of cream from milk, and the features which make it an essential departure
from the present accepted practice in this art, are the small diameter of the bowl

page_text: and the length of the same in proportion to the diameter in connection with which
are other features which adapt the bowl to be driven at a speed much higher than is
possible with bowls as at present constructed.
Centrifugal force is produced by two factors, one being velocity and the other
rotation, or change of direction, hence if the velocity remains constant the centrifugal
force will be as the revolutions.
The centrifugal force is greatly increased as compared with that of ordinary
separators by reducing the diameter of the bowl, and confining the liquid as closely
as practicable to the axis of rotation. This makes it possible to greatly increase the
number of revolutions and to develop a correspondingly greater centrifugal force
without overtaxing the strength of the bowl. For example, take a bowl 12 inches
in diameter running at its maximum speed, developing the greatest centrifugal force
which bowl of this diameter is able to sustain, and compare with this a bowl
1 inches in diameter, or just the diameter of the former running at the same
peripheral velocity. The latter bowl makes eight times the number of revolutions
of the former bowl and therefore according to the rule just stated, developes eight
times the centrifugal force, and since its mass is th of that of the former bowl its
burden will be eight times th or th of that of the bowl of greater diameter, which
is the tensile strain it is calculated to sustain, assuming that the metals of the two
bowls are of the same tensile strength, and that the thickness of the shells are in the
same proportion as their diameters.
From this it will be seen that the two bowls can be run at the same maximum
peripheral velocity, and that, at the same peripheral velocity, the bowl of smaller
diameter treats its contents by an effective force eight times as great as the bowl of
larger diameter.
The frictional resistance which any particle of liquid has to overcome in travelling to
its proper place in the bowl is caused by the pressure of other particles against it
which are not going in the same direction and the smaller the globule treated, the
greater in proportion to its mass is the frictional resistance to its movement and the
greater the force required to move it. A centrifugal force which is just equal to the
frictional resistance of the most minute globules cannot move them at all, while a force
that is slightly greater will move them tardily. If, however, from three to eight times
the force be applied the action becomes so much greater than the resistance that the
particles move promptly and the separation is not only rendered complete, but is
effected in a very much shorter time, furthermore, as the thickness of the milk wall in
the small diameter bowl is much less than in a bowl of large diameter the cream
globules from the outside layer of milk do not have to travel so far before reaching
the cream wall, for instance, comparing a twelve inch bowl and a four inch bowl each
having a two inch space inside of the creatn wall, in the twelve inch bowl the globule
of cream from the outermost part of the mass, (the point of maximun centrifugal
force), will have to pass through a wall of milk five inches in thickness in order to gain
the cream wall, while in the case of a four inch bowl, it will only have to pass through
a wall of milk one inch in thickness.
It would be impossible to run a bowl of large diameter at the very high speed at
which a bowl of small diameter can be driven, for the reason that if the centrifugal
force on the bowl of large diameter were increased, the said bowl would burst under the
strain to which it was subjected, the strain at any given cross section of the bowl
having the diameter of the bowl as one of the factors in its estimation, hence a speed
of about seven thousand revolutions per minute represents the maximum safe working
peed of separator bowls under present conditions, but, by reducing the diameter of the
owl, the desired increase in centrifugal force can be gained without risk of unduly
training the bowl.
The speed at which a bowl can be run is only limited by the strain which the bowl
an sustain without breaking, and it is advisable to use a speed as high as is practicable
vithin the limits of safety.
The diameter of the bowl is not likely to exceed 4 to 5 inches since the practicable
trength of a bowl of greater diameter than this would necessitate a slower sneed of

page_text: rotation than is desirable, but the length of the bowl is only restricted by the
circumstances under which it is used, and by mechanical limitations such as the weight
on the bearings. It is, however, inadvisable to make the bowl less in length than
5 or 6 times its diameter otherwise its capacity will be unduly limited, even though
it be run at the highest practicable speed.
In the bowl shewn in Figures 1 and 2 the upper outlet 27 of the tubular stem 23
provides for the escape of a certain quantity of skim milk which finds its way downward
through the bearing from said stem 23, and finally escapes into the general skim milk
chamber which receives the discharge from the opening 24, thus performing the same
lubricating function for the upper bearing of the bowl, which the full milk performs
for the lower bearing.
These features of this invention while not absolutely necessary to the proper carrying
out of the same, are preferably used in all cases, and they can, if desired, be employed
in machines differing in constructive detail from that shewn in Figures 1 to 5, for
instance, in Figure 6 I have shewn the upper end of a bowl into which the full milk is
introduced through a central pipe 35, the escape of skim milk and cream being as
shewn in Figure 2, and in Figure 7 I have shewn a lower bearing in which a rigid
spindle 36 is combined with a vertically channeled bearing block 37 with an elastic
annular supporting ring 38 surrounding the same so as to permit of the desired
limited lateral play, the full milk rising through the channels of the bearing into the
chamber 34 above the same.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what
I claim is :----
"
1. Centrifugal separating apparatus in which a bowl having relative diameter and
length substantially as hereinbefore explained is combined with ineans for rotating it
at high speed:
2. Centrifugal separating apparatus in which are combined, an upright bowl, a
supporting spindle at the bottom of the same, having a laterally flexible, or elastic,
portion, a support for the lower end of the said spindle, and a depending hood
surrounding the spindle and serving to limit the lateral vibration thereof substantially
as hereinbefore described.
3. Centrifugal separating apparatus in which are combined, an upright bowl of
small diameter having a projecting spindle at the lower end, a ball providing an end
support for the said spindle, other balls providing lateral support therefor, washers
upon which the said balls rest, and springs for supporting the said washers, substantially
as hereinbefore described.
4. Centrifugal separating apparatus in which are combined, an upright bowl, a
vertically elastic step bearing for the spindle of the same, and balls constituting a
lateral bearing for the said spindle, substantially as hereinbefore described.
5. Centrifugal separating apparatus in which are combined, an upright bowl, having
a lower spindle with tapered, or conical, portion, balls, forming a bearing for the said
conical spindle, and a vertically elastic support for the said balls, substantially as
hereinbefore described.
6. Centrifugal separating apparatus in which are combined, an upright rotating
bowl, and a bearing for the said bowl having separated portions bearing upon the
rotating part, whereby they are free to yield to constitute a flexible contact surface,
substantially as hereinbefore described.
7. Centrifugal separating apparatus in which are combined, an upright rotating
bowl, and a bearing therefor consisting of separated fibres presenting their ends to the
rotating part, whereby they constitute a flexible contact surface, substantially as
herein before described.
8. Centrifugal separating apparatus in which are combined, an upright bowl
having an upper spindle, blocks having projecting bristles, or fibres, bearing against
the said spindle and constituting the bearing therefor, and a receptacle for the said
blocks, substantially as herein before described.

page_text: 9. A centrifugal separating apparatus having a bearing lubricated by the liquid
which is being acted upon.
10. A centrifugal separating apparatus having a bearing through which the liquid
to be treated flows on its way to the bowl and serves as a lubricant for the said
bearing.
11. A centrifugal separating apparatus having a bearing through which one of the
separated bodies of liquid flows after leaving the bowl, and serves as a lubricant for the
said bearing.
12. A centrifugal separating apparatus having a bearing with a chamber above it
and a chamber below it, a separating bowl having a casing projecting into the said
upper chamber and enclosing a passage communicating with the bowl, a receptacle
communicating with the lower chamber and supplying thereto the liquid to be
separated, and means whereby the said liquid, in flowing from the lower to the upper
chamber, is caused to pass through the bearing and lubricate the rotating part which
turns therein, substantially as hereinbefore described.
13. A centrifugal separating apparatus having a separating bowl with an upper
spindle, a bearing therefor, and two outlets, and an outlet for a separated portion of
the liquid situated above the said bearing whereby the liquid escaping through the
said outlet is caused to pass down through the bearing and lubricate the upper spindle
of the bowl, substantially as hereinbefore described.
Dated this 20th day of May 1897.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.