An Improved Method of and Apparatus for Pasteurizing or Sterilizing Milk and other Fluids.
Year: 1893

page_text: Date of Application, 24th July, 1893-Accepted, 16th Sept., 1893
COMPLETE SPECIFICATION.
An Improved Method of and Apparatus for Pasteurizing or
Sterilizing Milk and other Fluids.
I, FREDERICK AUGUST KLEEMANN of 9 Luisenplatz, Berlin, Germany,
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 :-
This invention has for its object to effect, by an improved method and apparatus,
a continuous pasteurization or sterilization of milk and other fluids, and also, if
necessary, to subsequently quickly cool, to a low temperature, the fluid acted
upon.
As is well known, to properly pasteurize or sterilize liquid, it is necessary that
they should be heated to a certain maximum temperature. This maximum
temperature must be steadily maintained for a longer or shorter period according
to the nature of the fluid being treated. If this maximum temperature is not
reached, then the liquid will not be preserved, and the germs or infectious particles
will not be destroyed, and, if the temperature is permitted to rise above the
maximum, the liquid runs the risk of being spoiled through overheating or
burning.
Although various methods are known whereby liquids, such as milk, may be
pasteurized or sterilized none of the methods heretofore adopted are capable of
maintaining the liquid, while under treatment, at a constant and unvarying
maximum temperature, nor, if the liquid requires to be subsequently cooled, are
they capable of quickly cooling it down to a low temperature such as say 12°
to 15° centigrade.
With my invention the liquid can be readily and efficiently pasteurized or
sterilized be subsequently quickly cooled down to a low temperature. The
sterilizing and cooling operations may be continuous.
And in order that my said invention may be properly understood I have hereunto
appended three explanatory sheets of drawings, whereon
Figs. 1 to 4 represent the sterilizing or pasteurizing apparatus whilst Figs. 5
to 8 show the cooling device.
Fig. 1 is a vertical section of the sterilizer or heater taken on the line a―x of
Fig. 2, whilst Fig. 2 is a cross section on the line y-y of Fig. 1.
Fig. 3 is a part section of the heater on the line 2,-z, Fig. 4 whilst Fig. 4 is a
plan of Fig. 3.
Fig. 5 is a vertical section of the cooler taken on the line x-x¹ Fig. 6, and
Fig. 6 is a cross section on the line y-y' Fig. 5.
Fig 5 is a vertical section of a modified construction of heater and Fig. 6ª a
cross section of Fig. 5A.
Fig. 7 is a part section of the cooler Fig. 5 on the line - Fig. 8 whilst Fig. 8
is a plan view of Fig. 7.
Fig. 9 shows the heating and cooling devices connected together so that the
whole apparatus can be worked continuously.
Fig. 10 is a vertical section of a device for removing gases and air from
milk.
Fig. 11 shows a modified form of apparatus used for treating skim and sweet
milk for preserving purposes.
Figs. 12 and 13 are views of a milk vessel or receiver and pipe connections.
Fig. 14 is an enlarged sectional view of the lid of the milk vessel or
receiver.

page_text: The present invention is worked on the same general principle as, and is a
development of Fitzpatrick's invention No. 513 of 1893.
The methods of working hereinafter described refer to the treatment of milk, as
it is the most difficult liquid to properly sterilize.
The treatment of skim milk is slightly different to that of sweet milk.
When treating skim milk in order to kill any infecting germs in it, the apparatus
shown at Figs. 1 to 9 is used. This apparatus consists of a vessel A which is
made, preferably, cylindrical in shape and has fitted in it a heater B, which, either
alone or in conjunction with a heating jacket a, heats the milk which is caused to
flow into the interior of the vessel A.
The heater B consist of a hollow body which is divided by a horizontal
partition c into two compartments d and e.
Tubes are fitted at their upper ends in the bottom of the compartment d of
the body band, in these tubes, which are, as shown, closed at their lower ends,
smaller concentric tubes g are fitted. These tubes g which are open at both ends,
pass, at their upper ends, through the compartment d and are so secured to the
partition plate c as to only communicate with the compartment e. As will be
seen the lower ends of the internal tubes 9 reach nearly to the bottom of the
tubes f.
The heating medium which is, preferably, steam, although any suitable liquid or
gas can be used, is led by the pipe connection i to the lower compartment & of the
heater and from thence it passes down through the hanging tubes f to the bottom
of the vessel and returns, by the small internal tubes g, in the form of water of
condensation, to the upper compartment e from whence it is drawn off by the
connection k. Steam may be supplied to the heating jacket a by means of the
connection and be drawn off by the connection m.
The body is formed with a flange which enables it to be so secured, by screws n,
to the vessel A so as to form a lid or cover.
o is a stirring or agitating device, which consists of a number of vertical arms p
connected together at top and bottom and projecting up, through the milk, between
the tubes. The agitator is so fixed on a vertical driving spindler, which passes
through a stuffing box g at the bottom of the vessel A, as to be capable of being
easily removed when desired. The spindle is rotated by means of bevel gearing
actuated by a short shaft c2 carrying fast and loose belt pulleys t.
S
The milk passes into the vessel Å through the socket at its underside and is
withdrawn through the connection at its upper side, so that any generated vapours
and any gases contained in the milk may freely escape.
Thermometers x, y, (Fig. 4) may be suspended in the milk at different levels
in order that the temperature of the milk, at different depths, may be easily
ascertained.
The only essential difference in structure between the heating device and the
cooling device (see Figs. 5, 6, 7 and 8) is that the latter has no agitator.
The construction of cooler is shown at Figs. 5 to 8. It consists of a cylindrical
milk receiver or vessel A¹ which is provided with a cooling jacket a¹ extending
around its sides and bottom and a cooling body B. This body is divided, as
before, by a plate c¹ into an upper compartment e¹ and a lower compartment d¹.
The concentric tubes f¹ and glare connected to the body, the large tubes f¹ com-
municating with the compartment and the small tubes g¹ with the compartment e¹.
The tubes g' are like the tubes g, Fig. 1, open at both ends.
The cooling medium, which is preferably water, although any other suitable gas
or liquid may be used, is introduced, by the pipe connection to the compartment d¹
and tubes. The water flows down these tubes and returns by the small tubes f¹
to the compartment e¹ from whence it escapes by the connection k'. The water or
other cooling liquid flows into the jacket a¹ through the connection l¹ and out
through the connection m¹.
The milk flows up into the vessel A¹ through the connection ³ and is withdrawn
through the connections see Figs. 7 and 8.

page_text: The bottom of the body B¹ serves as a lid for the vessel A' to which it is
secured by bolts or screws n¹.
x²—y' Figs. 6 and 8 are thermometers for indicating the temperature of the milk
at various depths.
The construction of the apparatus may be slightly altered to suit local requirements
and different methods of treating the milk.
For dairy purposes it is quite sufficient if the skim milk is so treated as to retain
its sweetness for only a few days. In such cases it is necessary that the skim milk
should be kept for a certain time at a temperature of from 75 to 100 degrees
centigrade and it is also necessary at this temperature, that the milk should not be
allowed to burn, and, that when the skim milk is transferred to the heater the foam
should be retained. My apparatus as shown at Figs. 1 to 8 will be found to comply
with these conditions.
The retention of the foam is effected by means of a foam collector C (see Fig. 1)
which is fitted on the inflow pipe w'. This foam collector consists of a vessel which
is provided, at its underside, with two connections 1, 2, for the influx and efflux of
the milk to and from its interior. 3 is a float for closing valve 4.
As the milk passes through the vessel the foam collects within it and passes out
through the valve 4. Should the milk rise up to too high a level the float, by its
buoyancy, is caused to rise and close the outlet 4. When the milk sinks down again
so as to permit the foam to gather, the float also sinks with it and leaves the
outlet 4 open.
The parts of the apparatus are preferably arranged as shown at Fig. 9. As will
be seen the cooler A¹ is placed below the level of the heater in order to allow the
milk to flow by gravitation from the heater to the cooler. If the cooler cannot be
placed at a lower level then the milk from the heater must be raised artificially to
the cooler.
The working of the apparatns as shown at Fig. 9, which arrangement is suitable
for dairies, is as follows
At the commencement the heater A is filled with inilk up to the level of the
test cock 5 (see Fig. 1) on the pipe v. The cock 5 is then closed and further
inflow of milk is stopped. The stirring or agitating apparatus o is put into motion
while the milk is flowing in and is kept in motion until all the milk has been
treated. As soon as the heater is filled with milk steam is let into the jacket a and
heating body B.
As soon as the thermometers x and y indicate that the milk already in the heater
has attained the desired temperature the remainder of the milk to be treated is
allowed to flow continuously into the heater and at the same time, the heated milk
is allowed to flow continuously from it through the connection and tubes 6, 7,
(see Fig. 9) and through the inlet u' to the cooler A' which has previously been
supplied with cooling fluid. The temperature of the heated milk as it flows into
and through the cooler A' is lowered to the desired extent. The cold and sterilized
milk delivered from the cooler is conducted by the pipes 8 and 9 to the usual storage
or transport vessels or receptacles.
The last supply of milk to the heater A, after having been sufficiently heated, is
withdrawn through the valve 10, at the bottom of the heater, and conducted by
the pipe 11 to the pipes 6 and 7 and cooler A¹. When the milk supply to the
cooler has been stopped the charge remaining within it is withdrawn through the
cock 14 (see Fig. 9).
The cock 13 (Fig. 9) is used for filling storage vessels with milk.
After the heater A. and cooler A have been emptied the agitator o is stopped
and the tubes and vessels thoroughly cleaned.
The treatment hereinbefore described is not sufficient if skim and sweet milk
have to be kept in a sound condition for a long time. In such a case the following
reatment has to be adopted.
The sweet milk has, at first, to be freed from all accidental admixtures. This is

page_text: not necessary with the skim milk as it sufficiently purified after passing through
the cream separators.
The purified sweet milk or the skim milk is heated in the heater A up to a
temperature of 105° to 120° centigrade and kept at this temperature for some time,
it is thereafter freed from the absorbed gases and then passed to the cooler where
it is cooled down to 12° to 15° centigrade. From the cooler it is as before drawn
off into storage or transport vessels which have been previously sterilized.
It is, of course, necessary that the milk should not come in contact with
atmospheric air from the time it enters the heater till it is finally closed or sealed
up in the transport or storage vessels.
It is also necessary that the whole apparatus with its tubes etc. should be
thoroughly sterilized before the work comm'nees. If the operation is to be
continuous it is necessary to have, as before two apparatuses namely a special
heater and a special cooler but if the working is only periodical the cooler may be
dispensed with and the heater used for both the heating and cooling operations.
The apparatus may be arranged in different ways but I prefer to make it as
shown at Fig. 11.
A special apparatus D is fitted on the pipe connection between the heater and
cooler for the purpose of removing gases and air from the milk. The apparatus is
shown to an enlarged scale at Fig. 10. It consists of a vessel 15 the lid 16 of which
is removable for cleaning purposes. The milk enters the vessel, from the heater,
through the connection 17 and flows out again, through the connection 18 to the
cooler. Within the vessel 15 are insertions 19 and 20 which are loosely hung upon
supports 21 and also an insertion 22 fixed to the lid 16. 23 and 24 are weighted
valves.
The mode of operation is as follows:-
At first the heater A is filled with milk up to the level of the test cock 5 (see
Fig. 1). The agitator is put in motion while the heater is being filled and when
it has been filled, further supply is cut off and steam is admitted to the jacket a and
body B. If the temperature of the milk in the heater rises to 105° C. or above it
the valve 23 will rise being weighted sufficiently to remain closed on its seat at a
lower temperature. A continuous supply of milk to the heater is now turned on
and the heated milk flows from the heater through the pipe 6 valve 23 and vessel D.
The valve 24 is not so heavy or is not weighted to the same extent as the valve 23
and as a consequence gas and air bubbles from the milk can freely escape through
said valve to the atmosphere. The insertions 19, 20 and 22 prevent the milk
passing out through the valve 24.
The now disaired milk passes through the tubes 25, 26 and connection at the
bottom of the cooler A¹ up through said cooler and out again by the connection v³
and tube 27 to the filling apparatus.
The filling apparatus is shown at Figs. 12, 13, and 14 it consists of a branch
cock 28 the plug of which communicates on one hand with a milk tube 29 and on
the other hand with a steam tube 30. The milk transport or store vessel 31 is
tightly coupled by the coupling 40 to the cock 28. The vessel 31 has a special
construction of lid 32 which is provided with two cocks 33 and 34 provided
respectively with a long tube 36 which nearly descends to the bottom of the vessel
and a valve 35 which is capable of opening outwards automatically. The lid 32
which is fitted air-tight to the vessel 31 is coupled by means of the cock 33 to the
cock 28.
The vessel 31 is first turned bottom upwards as shown at Fig. 13. and when this
has been done, the cocks 33 and 34 and steam valve 37 are opened, when the steam
will enter at the highest point through the tube 36, and drive out the contained
heavy air and condensed water through the cock 34 and valve 35 thereby sterilizing
the vessel 31.
After the vessel 31 has been sterilized it is turned down into the position shown
at Fig. 12 and the steam valve 37 is shut. The cock 28 is also turned so as to

page_text: The cooled milk now
When the milk begins to run
communicate with the milk pipe 29 as shown at Fig. 12.
flows into the vessel 31 and fills it up to the top
out of the valve 35 it indicates, at once, that the vessel 31 is full. The cocks 28, 33
and 34 are now shut and the vessel 31 is uncoupled from said cock 28 and replaced
by another vessel which is filled in the same manner.
When the last supply of milk to the heater has been sufficiently heated the steam
supply to the jacket a and body B is shut off, the cock 10 on the heater is opened,
and the milk allowed to run off through the tubes 11, 12, 26 to the cooler. The
last supply in the cooler is withdrawn through the cock 13 (Fig. 11) and passes
down the pipe 29 into the storage or transport vessel.
In order to sterilize the apparatus before commencing operations the cocks 10
and 13 are opened and the branch cock 28 is turned into the position shown at
Fig. 12. Steam is now passed into the heater through the branch 38 (see Fig. 4)
spreading itself throughout the interior of the apparatus and thoroughly sterilize
it. The air and condensed water passes out by the branch cock 28.
If so desired the body B or B₁ may be at the bottom of the heater instead of at
the top.
If so desired the heater may be modified in its construction as shown at Figs. 54
and 6ª. In this case the heater is preferably of cylindrical or prismatic form and
has a hollow chamber at top and bottom as shown. The hollow chambers g², l²,
are connected together by means of vertical pipes & in which are suspended con-
centrically the heating or cooling tubes c², 2. These tubes c², f, which are
arranged in the same manner and perform the same functions as at Figs. 1 and 5
are secured to the hollow body B2 which as before, is divided into compartments d'
and e² by the partition 12. The body B2 is removably secured to the chamber g²
by the thumb screws and the bottom plate ¹ of the chamber h² is or may be
removably secured by thumb screws t¹.
The liquid to be heated or cooled is supplied through the branch from whence
it passes into the chamber h², up the tubes to the chamber g², and from thence
out again by the branch m². The heating or cooling fluid passes into the com-
partment (2 of the body 132 through the connection p then down the tubes c³ and
up the internal tubes 2 to the compartment from whence it escapes by the
outlet Heating or cooling fluid is also supplied to the casing A³, through the
branch u², from whence it passes out again through the branch o
With this arrangement, Figs. 5 and 6, the milk is divided into a number of
thin columns which are acted upon both from the inside and the outside.
As the ends of the apparatus can be easily taken off by releasing the screws t
the whole of the interior and tubes can be easily and thoroughly cleaned.
and
If so desired the tubes f, g, may be supported from below.
The tubes may be fitted obliquely if so desired.
In all cases I use hanging or standing heating or cooling tubes.
It is evident that the above apparatus is equally suited for pasteurizing or
sterilizing and cooling other liquids as well as milk.
The modus operandi may be reversed if so desired.
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 method of treating milk and other fluids, consisting in first passing the
fluid to a heater where it is heated by means of heating surfaces immersed in the
fluid to a certain temperature and sterilized, then passing it, by means of pipe
connections, to a device for denuding it of air and thereafter passing it into an
apparatus where it is cooled by means of cooling surfaces immersed in the fluid,
substantially as hereinbefore set forth.
2. The combination with the heater of a cooler having tubular cooling surfaces,
arranged and constructed substantially as hereinbefore described and shown at
Figs. 5 to 8 of the drawings annexed.

page_text: 3. The modified form of cooler (or heater) substantially as hereinbefore described
and shown at Figs. 5 and 6 of the drawings annexed.
4. The combination with the heater (A) of the foam collector (C) substantially
as hereinbefore described and shown on the drawings annexed.
5. The dis-airing device D, substantially as and for the purpose hereinbefore set
forth.
6. The air-tight lid or cover 32 having a cock 34 provided with an outlet
valve 35 and a cock 33 provided with a tube 36, substantially as and for the
purpose herein before set forth.
Dated this 22nd day of July 1893.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.