An Improved Process of and Apparatus for Sterilizing Liquids.
Year: 1893

page_text: PROVISIONAL SPECIFICATION,
An Improved Process of and Apparatus for Sterilizing Liquids.
We, GEORG POPP Ph.D. and JOHANN HEINRICH BECKER Ph.D. both of
153, Fenchurch Street, in the City of London, Chemists, do hereby declare the
nature of this invention to be as follows:-
This invention relates to a process for sterilizing liquids, more especially milk, in
large quantities and without the detrimental effects consequent on the present
mode of sterilization which is effected by externally heating receptacles containing
the liquid which, in the case of milk, renders the same unpalatable probably owing
to its being locally overheated which cannot be entirely avoided, even by
vareful stiring. Sterilization by the direct introduction of steam into the liquid
has not been hitherto attempted, for fear of imparting an objectionable taste to,
and of diluting, the liquid.
The sterilization of milk on a large scale has not been generally successful
because the milk has either been excessively heated, thus causing it to change
color and acquire a disagreeable flavor (the process by which the disagreeable
flavor is removed-viz. by passing sterilized air through the sterilized milk-being
very complicated and unreliable) or it has been insufficiently heated and
consequently imperfectly sterilized.
Our process consists in first heating the milk to the boiling point, or nearly so,
and then introducing steam into the liquid, the external heating being meanwhile
continued. In carrying out the invention, the steam is introduced preferably at the
bottom of the liquid in a number of small jets in such manner that it thoroughly
permeates the liquid and sets up a rapid circulation. The whole of the milk
particles are thus brought expeditiously into intimate contact with the steam and
sterilized, thus obviating local overheating which caramelizes the milk sugar or
otherwise gives rise to a disagreeable boiled taste. When steam is introduced into
the liquid and the external heating thereof properly effected, no condensation takes
place or at any rate so little that it has no appreciable effect. For instance we
have found that after operating with steam for a period of thirty-five minutes the
milk was only diluted to the extent of about three per cent. The process, however,
might be objected to on the ground that the fatty constituents of the milk are
distilled off by the passage through it of the steam, but this loss has been
determined and compared favorably with other known processes for sterilizing
milk. But, however this may be, the fatty substance carried off with the steam can
be readily recovered by condensation in a cooling coil so as to constitute a valuable
substance which may he readily turned to account and materially reduce the
working costs of the process. In the preservation of other substances, such
as meats, soups, fruit, etc., this invention enables other substances, such as fatty
acids, fruit acids, etc., to be recovered. By directly boiling with steam the original
taste, odor, and appearance of the liquids treated are obtained intact without
necessitating any additional aeration with specially sterilized inert gases while by
means of this process, in order to ensure the annihilation of germs, the sterilizing
operation can be continued for a much longer period without detriment to the
quality, and without in any way limiting the quantity, of liquid to be operated on.
According to this process the heating of the liquid is effected in a jacketed
container or other indirectly heated vessel until it attains the temperature of the

page_text: steam whereupon the latter is at once introduced into the liquid which is thus
energetically agitated, the indirect heating and the introduction of steam being
continued until the completion of the process whereupon the sterilized liquid is
charged into vessels which have been previously sterilized by the introduction of
steam. If it be desired to thicken the liquid this is effected with the aid of a
vacuum, special importance being attached to the fact that this inspissation under a
vacuum in presence of steam can be carried out concurrently with, or subsequently
to, the sterilization and in the same or similar apparatus connected thereto. The
passage of steam during the inspissation affords protection, particularly in the case
of milk, against decomposition of the chemical constituents of the substance treated.
The apparatus consists of a closed vessel having an inner casing or shell, a
steam-tight space or chamber being left between the two. A steam supply pipe is
introduced at the upper part of the vessel and extends down close to the bottom of
the container at one side where it terminates preferably in a bent end, which
is perforated with numerous holes, its other end being attached to the steam main.
The steam pipe is provided with a regulating stop-valve and it is either bent and
provided with a drain-cock or furnished with a steam-trap. Steam is introduced
into the space between the vessel and the inner shell by a pipe connected with the
steam main, and the apparatus is provided with a man-hole in the cover for enabling
the vessel to be cleaned out, there being a safety-valve and an inlet-cock for the
admission of germ-freed air during the emptying of the apparatus. A pipe conveys
the steam from the upper part of the container to a cooling coil which leads into a
separating vessel so that when fatty liquids such as milk, etc., are being sterilized
(the water and fatty matter being then separated by gravity) the water is caught in
one vessel and the fatty substance in another. A water gauge is attached to the
vessel for observing the rise of the liquid undergoing sterilization when steam is
introduced and during the indirect heating thereof, and its fall on completion of the
operation, and also any addition to the quantity of liquid due to condensation. A
thermometer is suspended within the vessel and its stem passes out and is attached
to the exterior of the vessel in order that its indications may be observed.
apparatus is furthermore provided with a funnel for feeding in the liquid to be
sterilized and with a cock for drawing-off the sterilized charge. A cock is attached
to the bottom of the apparatus, for draining off the water of condensation from the
chamber or steam space or in lieu of this a pipe connected with a steam trap may
be employed. This steam space is also provided with an exhaust and safety-valve.
The operation is as follows: The liquid to be sterilized having been run into the
vessel steam is slowly admitted to the steam spare or chamber between the vessel
and the inner shell and when the thermometer indicates that the liquid bas atteined
approximately the temperature of the steam to be introduced into it, the inlet valve
is opened and the steam is conveyed directly into the liquid through the perforated
pipe, preferably, in an oblique direction for the purpose of promoting the circulation.
This energetically agitates the whole body of liquid and whilst thoroughly heating
the liquid prevents its being locally overheated and kills the germs. By carefully
observing the thermometer and the temperature of the steam-jacket, the temperatures
can be so regulated that no condensation of the steam introduced, with consequent
dilution of the liquid, takes place.
The
A vacuum pump is attached to the apparatus if it be desired to employ it for
inspissating liquids during or after their sterilization.
The steam-jacket for indirectly heating the liquid may of course be replaced by
a heater such as a steam coil or the like placed within the container or by a direct
heating contrivance whose action can be profitably transferred immediately to a
liquid. The contrivances for indirectly heating may, after the sterilizing, of course
be used for rapidly cooling the liquid by the passage through them of cold
water, etc. To promote the circulation of the liquid caused by the direct
introduction therein of the steam, the container may be provided with gills.
It is to be understood that sterilizing by the process of our invention
may
ha

page_text: effected in portable vessels and the sterilization may be carried out by introducing
a steam-pipe into large milk cans and placing these in a water bath or the like.
Dated this 18th day of March 1893.
J. H. BECKER.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents,
COMPLETE SPECIFICATION.
An Improved Process of and Apparatus for Sterilizing Liquids.
We, GEORG Porr Ph.D. and JOHANN HEINRICH BECKER Ph.D. both of
153, Fenchurch Street, in the City of London, Chemists, 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 relates to a process for sterilizing liquids, more especially milk, in
large quantities and without the detrimental effects consequent on the present mode
of sterilization which is effected by externally heating receptacles containing the
liquid which, in the case of milk, renders the same unpalatable, probably owing to
its being locally overheated which cannot be entirely avoided even by careful
stirring. Sterilization by the direct introduction of steam into the liquid has
practically not been hitherto attempted for fear of imparting an objectionable taste
fo, and of diluting, the liquid.
The sterilization of milk on a large scale has heretofore not been generally
successful because the milk has either been excessively heated, thus causing it to
change color and acquire a disagreeable flavor which has to be got rid of by
passing sterilized air through the sterilized milk, which is both a complicated and
unreliable operation, or it has been insufficiently heated and consequently imperfectly
sterilized.
Our process consists in first heating the milk to the boiling point, or nearly so,
and then introducing steam into the liquid, the external heating being meanwhile
continued. In carrying out the invention, the steam is introduced preferably at the
bottom of the liquid in a number of small jets, in such manner that it thoroughly
permeates the liquid and sets up a rapid circulation. The whole of the milk
particles are thus brought expeditiously into intimate contact with the steam and
sterilized, thus obviating local overheating which caramelizes the milk sugar or
otherwise gives rise to a disagreeable boiled taste. When steam is introduced into
the liquid and the external heating thereof properly effected, no condensation takes
place, or at any rate so little that it has no appreciable effect. For instance, we
have found that after operating with steam for a period of thirty-five minutes, the
milk was only diluted to the extent of about three per cent. The process, however,
might be objected to on the ground that the fatty constituents of the milk are
distilled off by the passage through it of the steam, but this loss has been deter-
mined and compared favorably with other known processes for sterilizing milk.
however this may be, the fatty substance carried off with the steam can be readily
recovered by condensation in a cooling coil, so as to constitute a valuable substance
which may be readily turned to account and materially reduce the working cost of
the process. In the preservation of meats, soups, fruit, etc., this invention enables
substances, such as fatty acids, fruit-acids, ., to be recovered. By directly
boiling with steam, the original taste, odor, and appearance of the liquids treated
are obtained intact without necessitating any additional aeration with specially
sterilized inert gases, while by means of this process, in order to ensure the
annihilation of germs the sterilizing operation can be continued for a much longer
period without detriment to the quality, and without in any way limiting the
quantity, of liquid to be operated on.
But

page_text: According to this process, the beating of the liquid is effected in a jacketød
container or other indirectly heated vessel until it attains the temperature of the
steam whereupon the latter is at once introduced into the liquid which is thus
energetically agitated, the indirect heating and the introduction of steam being
continued until the completion of the process, whereupon the sterilized liquid is
charged into vessels which have been previously sterilized by the introduction of
steam. If it be desired to thicken the liquid, this is effected with the aid of a
vacuum, special importance being attached to the fact that this inspissation under a
vacuum in presence of steam can be carried out concurrently with, or subsequently
to, the sterilization and in the same or similar apparatus connected thereto. The
passage of steam during the inspissation affords protection, particularly in the case
of milk, against decomposition of the chemical constituents of the substance
treated.
The invention will be described with reference to the accompanying drawing,
forming part of this Specification, wherein
Figure is a vertical sectional elevation of the apparatus and Figure 2 a
horizontal section on line - Figure 1.
The apparatus consists of a closed vessel A having an inner casing or shell B, a
steam-tight space or chamber C being left between the two. A steam supply
pipe E is introduced at the upper part of the vessel and extends down close to the
bottom of the container at one side where it terminates preferably in a bent end F
which is perforated with numerous holes, as seen in Figure 2, its other end being
attached to the steam main K. The steam pipe is provided with a regulating stop-
valve G and it is either bent and provided with a drain-cock I or furnished with a
steam trap. Steam is introduced into the space C between the vessel A and the
inner shell by a pipe L connected with the steam main, and the apparatus is
provided with a man-hole N in the cover for enabling the vessel to be cleaned out,
there being a safety-valve 0 and an inlet cock j for the admission of germ-freed air
during the emptying of the apparatus. A pipe P conveys the steam from the
upper part 1 of the container to a cooling coil Q which leads into a separating
vessel R, so that when fatty liquids such as milk, etc., are being sterilized (the
water and fatty matter being then separated by gravity) the water is caught in one
vessel S and the fatty substance in another T. A water gauge U is attached to
the vessel for observing the rise of the liquid undergoing sterilization when steam
is introduced and during the indirect heating thereof, and its fall on completion of
the operation, and also any addition to the quantity of liquid due to condensation.
A thermometer V is suspended within the vessel and its stem passes out and is
attached to the exterior of the vessel, in order that its indications may be observed.
The apparatus is furthermore provided with a funnel X for feeding in the liquid to
be sterilized and with a cock y for drawing-off the sterilized charge, for doing
which the cock in the cover is opened. A cock Z is attached, to the bottom of
the apparatus, for draining-oft the water of condensation from the chamber or
steam space C, or in lieu of this a pipe connected with a steam trap may be employed.
This steam space ( is also provided with an exhaust and safety-valve LI.
The operation is as follows: The liquid to be sterilized having been run into the
vessel D, steam is slowly admitted through the pipe L to the steam space or
chamber C between the vessel and the inner shell and when the thermometer
indicates that the liquid has attained approximately the temperature of the steam
to be introduced into it, the inlet valve G is opened and the steam is conveyed
directly into the liquid through the perforated pipe E, preferably in an oblique
direction for the purpose of promoting the circulation. This energetically agitates
the whole body of liquid and whilst thoroughly heating the liquid, prevents its
heing locally overheated and kills the germs. By carefully observing the
thermometer W and the temperature of the steam-jacket C, the temperatures can
be so regulated that no condensation of the steam introduced, with consequent
dilution of the liquid, takes place,

page_text: A vacuum pump is attached to the apparatus if it be desired to employ it for
inspissating liquids during or after their sterilization.
The steam jacket for indirectly heating the liquid may, of course, be replaced by
a heater, such as a steam coil or the like, placed within the container B or by a
direct heating contrivance whose action can be profitably transferred immediately
to a liquid. The contrivances for indirectly heating may, after the sterilizing, of
course, be used for rapidly cooling the liquid by the passage through them of cold
water etc. To promote the circulation of the liquid caused by the direct intro-
duction therein of the steam, the container may be provided with gills.
It is to be understood that sterilizing by the process of our invention may be
effected in portable vessels and the sterilization may be carried out by introducing
a steam-pipe into large milk cans and placing these in a water bath or the like.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1st. The herein described process of sterilizing liquids, which consists in passing
steam through a heated liquid in a closed vessel, substantially as specified.
2nd. In the above claimed process, carrying away any water of condensation as
vapor by creating a vacuum above the liquid.
3rd. Sterilizing milk by heating it to, or nearly to, sterilizing heat by exposure
to hot surfaces and while maintaining the external heating, introducing steam into
the milk.
4th. In the process referred to in Claim 1, forming a vacuum above the liquid at
the end of the process for the purpose of removing any water of condensation as
vapor.
5th. In the process referred to in Claim 1, introducing the steam at one side of
the vessel.
6th. In the process referred to in Claim 1, introducing the steam in an oblique
direction, in order to promote the circulation of the liquid.
7th. The inspissation of liquids, constituting a modification of the process referred
to in Claim 1, by shutting off or diminishing the steam supply at the end of the
operation so as to create a vacuum above the liquid.
8th. An apparatus for carrying into effect the sterilizing process described,
consisting of a vessel A provided at its lower part with a container B serving as a
receptacle for the liquid to be sterilized and separated from the vessel A by a space
constituting a chamber C for the purpose of indirectly heating the liquid in the
container B by the introduction of steam therein, a pipe E for the introduction of
steam into the liquid in such manner that the liquid is set in rapid agitation, a
pipe P for the escape of the steam from the upper part of the vessel A and a coil Q
for the recovery of the fatty and other products of the distillation by condensation,
the condensation water being separated in vessels R, S, T, from the distillation
products.
9th. The employment, in lieu of the steam space surrounding the receptacle B
for externally heating the liquid, either of a heater or heating pipes, etc., introduced
into the liquid to be sterilized, or directly heating the vessel and providing the
internal surface of the receptacle B with gills for promoting the circulation caused
by the steam introduced therein.