U.S. patent number 3,619,126 [Application Number 04/398,240] was granted by the patent office on 1971-11-09 for method of continuously heat-treating products in sealed containers, and apparatus for performing the same.
Invention is credited to Pierre Carvallo.
United States Patent |
3,619,126 |
Carvallo |
November 9, 1971 |
METHOD OF CONTINUOUSLY HEAT-TREATING PRODUCTS IN SEALED CONTAINERS,
AND APPARATUS FOR PERFORMING THE SAME
Abstract
Method and apparatus for thermal treatment of products contained
in sealed containers, in which the containers are conveyed along a
path of travel comprising in succession at least one inlet
hydrostatic pressure column, at least one treatment chamber under
pressure and at least one outlet hydrostatic pressure column, the
containers traveling in said chamber in contact with a liquid
contained in said chamber and maintained to a predetermined
treatment temperature, the liquid and its vapor in said chamber
being subjected to an overpressure with a gaseous fluid, the
pressure of which is constantly maintained at a value greater than
the vapor pressure of said liquid at said treatment temperature,
said overpressure being balanced by said hydrostatic columns.
Inventors: |
Carvallo; Pierre (Paris, 16eme,
Seine, FR) |
Family
ID: |
8813408 |
Appl.
No.: |
04/398,240 |
Filed: |
September 22, 1964 |
Foreign Application Priority Data
Current U.S.
Class: |
422/25; 99/361;
422/38; 99/362; 99/443R |
Current CPC
Class: |
A23L
3/045 (20130101); A61L 2/07 (20130101) |
Current International
Class: |
A23L
3/04 (20060101); A23L 3/02 (20060101); A61L
2/04 (20060101); A61L 2/07 (20060101); A61l
001/00 (); A61l 003/00 (); A23l 003/04 () |
Field of
Search: |
;21/56,78,79,80,93,94
;99/362,249,251,214,215,216 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
1,278,910 |
|
Nov 1961 |
|
FR |
|
190,132 |
|
Nov 1907 |
|
DT |
|
974,659 |
|
Nov 1964 |
|
GB |
|
731,550 |
|
Jun 1955 |
|
GB |
|
Primary Examiner: Wolk; Morris O.
Assistant Examiner: Richman; Barry S.
Claims
What I claim is:
1. A heat treatment apparatus comprising means defining a
sterilizing constant pressure chamber, means defining a U-shaped
inlet hydrostatic housing with one end of said housing
communicating with one end of said pressure chamber, means defining
a U-shaped outlet hydrostatic housing with one end of said outlet
housing communicating with the other end of said pressure chamber,
means for directing a high-pressure heating medium into said
pressure chamber, means for directing a liquid preheating medium
into said U-shaped inlet housing, means for directing a liquid
cooling medium into said U-shaped outlet housing, means defining
two air chambers in open pipe connection with each other for
applying a common overriding air pressure to the other ends of said
housings, said air pressure being sufficient to maintain the level
of liquid in each of said U-shaped housings at different elevations
and to cooperate with the forces exerted by the so defined
unbalanced portions of liquid to balance the pressure within said
pressure chamber, and conveying means including carriers for
supporting and moving articles into and through said U-shaped inlet
housings, through said sterilizing pressure chamber, and through
and out of said U-shaped outlet housing without disturbing the
pressure balance within said housings.
2. A heat treatment apparatus comprising means defining a
sterilizing constant pressure chamber, means defining a U-shaped
inlet hydrostatic housing with one end of said housing
communicating with one end of said pressure chamber, means defining
a U-shaped outlet hydrostatic housing with one end of said outlet
housing communicating with the other end of said pressure chamber,
means for directing a high-pressure heating medium into said
pressure chamber, means for directing a liquid preheating medium
into said U-shaped inlet housing, means for directing a liquid
cooling medium into said U-shaped outlet housing, means defining
two air chambers in open pipe connection with each other for
applying a common overriding air pressure to ends of said housing,
said air pressure being sufficient to maintain the level of liquid
in each of said U-shaped housings and to cooperate with the forces
exerted by the liquids to balance the pressure within said pressure
chamber, and conveying means including carriers for supporting and
moving articles into and through said U-shaped inlet housings,
through said sterilizing pressure chamber, and through and out of
said U-shaped outlet housing without disturbing the pressure
balance within said housings.
3. Apparatus for continuous thermal treatment of products contained
in said apparatus in sealed containers, comprising in combination
an endless conveyor for transport of containers, a vessel having at
least one inlet hydrostatic column, means defining at least one
constant pressure treatment chamber communicating with said first
column, and at least one outlet hydrostatic column communicating
with said chamber, means for advancing said conveyor through said
vessel along a path of travel successively passing through the
inlet column, the treatment chamber and the outlet column, said
treatment chamber including a major portion of substantially
horizontal elongate form, a liquid filling said major portion of
the treatment chamber, means for maintaining said liquid at a
predetermined treatment temperature, means for introducing and for
maintaining in said chamber a gaseous fluid having an overpressure,
the value of which is greater than the vapor pressure of said
liquid at said temperature, said overpressure being balanced by
said columns, and idlers in said major portion of said treatment
chamber for said conveyor arranged to cause the conveyor to travel
in at least one substantially horizontal run through the liquid in
said major portion of the chamber.
4. Apparatus for continuous thermal treatment of products contained
in said apparatus in sealed containers, comprising in combination
an endless conveyor for transport of containers, a vessel having at
least one inlet hydrostatic column, means defining at least one
constant pressure treatment chamber communicating with said first
column, and at least one outlet hydrostatic column communicating
with said chamber, means for advancing said conveyor through said
vessel along a path of travel successively passing through the
inlet column, the treatment chamber and the outlet column, a liquid
with its vapor in said chamber, means for maintaining said liquid
at a predetermined treatment temperature, means for introducing and
for maintaining in said chamber a gaseous fluid having an
overpressure, the value of which is greater than the vapor pressure
of said liquid at said temperature, said overpressure being
balanced by said columns, and means in said treatment chamber for
dividing the liquid and impinging the same under pressure at said
treatment temperature against the containers along the length of
the conveyor in said treatment chamber.
5. Apparatus as claimed in claim 4 wherein said means for dividing
and impinging the liquid against the containers is located on both
sides of the conveyor.
6. Apparatus as claimed in claim 4 wherein said means for dividing
and impinging the liquid on both sides of the conveyor comprises a
pump connected to a reservoir of said liquid, maintained in the
chamber at said treatment temperature and overpressure, for
circulating the latter liquid and effecting division and direct
impingement thereof against the containers.
7. Apparatus as claimed in claim 4 comprising receptacles on said
conveyor for receiving the containers, said receptacles being
perforated over their entire surface to permit successive vertical
streaming along their length.
8. A method of continuous thermal treatment of products contained
in sealed containers, said method comprising the steps of conveying
said containers along a path of travel comprising in succession at
least one inlet hydrostatic pressure column, at least on treatment
chamber under constant pressure and at least one outlet hydrostatic
pressure column, forming said treatment chamber of substantially
horizontal elongate shape, filling said chamber with a liquid,
maintaining the liquid at a predetermined treatment temperature,
subjecting said liquid in said chamber to an overpressure with a
gaseous fluid, the pressure of which is constantly maintained to a
value greater that the saturated vapor pressure of said liquid at
said treatment temperature, said overpressure being balanced by
said hydrostatic columns, and passing the conveyor along at least
one immersed horizontal run in the liquid in said chamber.
9. A method of continuous thermal treatment of products contained
in sealed containers, said method comprising the steps of conveying
said containers along a path of travel comprising in succession at
least one inlet hydrostatic pressure column, at least one treatment
chamber under constant pressure and at least one outlet hydrostatic
pressure column, subjecting said containers traveling in said
chamber to the action of a liquid contained in said chamber and
maintained at a predetermined treatment temperature, subjecting
said liquid and its vapor in said chamber to an overpressure with a
gaseous fluid, the pressure of which is constantly maintained to a
value greater than the saturated vapor pressure of said liquid at
said treatment temperature, said overpressure being balanced by
said hydrostatic columns, said containers being subjected to the
action of said liquid by dividing the liquid and impinging the same
against the containers at said treatment temperature and pressure
along the length of travel in the treatment chambers.
10. A method as claimed in claim 9 wherein liquid is maintained in
the treatment chamber in a reservoir at the bottom thereof, and the
liquid which impinges on the containers is recirculated from said
reservoir.
11. Apparatus for continuous thermal treatment of products
contained in sealed containers, comprising an endless conveyor for
transport of containers, a vessel having at least one inlet
hydrostatic column, at least one vertical treatment chamber
communicating with said first column, and at least one outlet
hydrostatic column communicating with said chamber, means for
advancing said conveyor through said vessel along a path of travel
successively passing through the inlet column, the treatment
chamber and the outlet column, a treatment liquid at the bottom of
said vertical chamber, means for maintaining said liquid at a
predetermined treatment temperature, means for introducing a
gaseous fluid into said chamber and for maintaining at a constant
level the said liquid and for maintaining inside the treatment
chamber a constant overpressure the value of which is greater than
the vapor pressure of said liquid at said treatment temperature,
said overpressure being balanced by said hydrostatic columns, and a
circulating pump for pumping the treatment liquid at the bottom of
the treatment chamber and spreading it in divided form at the top
of the said treatment chamber.
Description
This invention relates to a method of continuously heat-treating
products in sealed containers and to apparatus for performing the
same, examples of such products being canned food, beverages,
pharmaceutical products and the like, the invention being more
particularly concerned with a continuous sterilization and cooling
process carried out under hydrostatic pressure.
In apparatus resorted to heretofore, sterilization usually takes
place in a chamber containing steam maintained under pressure: a
column of water of given height maintains this pressure and serves
as a passageway for introducing and withdrawing the products.
The temperature prevailing in such a chamber depends on the
pressure. Now when products in sealed containers are heated, the
pressure inside the containers becomes greater than the external
pressure, so that it is necessary to design and use containers and
seals capable of withstanding the stresses developed thus by the
internal overpressure.
The present invention has for its object to permit, by working with
an external hydrostatic overpressure, the use of containers or
container sealing means which are incapable of withstanding an
internal overpressure or which are not strong enough to be
processed by normal methods.
It is accordingly one object of the invention to provide a method
of continuously heat-treating products in sealed containers,
consisting in treating said products in at least one chamber
containing a liquid raised to the required temperature and which is
kept at an overpressure by means of a gaseous fluid whose pressure
is in turn kept constant by at least one column containing a
liquid, through which column said products enter the processing
chamber and emerge therefrom in continuous fashion.
In an alternative way of performing the method hereinbefore
described, and in order to considerably improve the efficiency of
the heat exchange process with the treated products, the liquid
which is raised to the required temperature under gaseous
overpressure may be caused to act upon the containers not only by
immersion, but also by streaming, spraying, misting and
atomization. This avoids the use of too large a volume of liquid
and the expenditure of setting under temperature, thus enabling
operating time to be cut down. Moreover, the heat transfer is
improved through speeding up of the circulation rate over the
container walls; also, this avoids subjecting the containers to
pressures that vary with immersion depth.
Another advantage of this alternative form is the readiness with
which the sterilization process can be halted and resumed in cases
where the conveyor is stopped deliberately or inadvertently, since
all that is necessary is to halt the spraying or streaming action
at the same time.
Such a method additionally permits easy conversion of existing
sterilization apparatus for the purpose of adapting the spraying
components to them and thereby conferring upon them the advantages
cited precedingly.
Still another advantage stemming from the spraying type of
treatment is that it enables the processed containers to be
agitated as a result of the high-pressure spray jets impinging upon
them.
In yet another alternative mode of performing the subject method of
this invention, the action exerted on the containers is made more
thorough by so directing the liquid circulation streams that the
contact taking place between these streams and the containers to be
processed be extended and improved.
In accordance with the present invention, in cases where a spraying
system is utilized, the liquid is accordingly sprayed in lateral
and preferably staggered jets whereby to cover the entire area
presented by the containers passing through the treatment
chamber.
The spraying may be performed mechanically under the effect of the
pressure imparted to the liquid, or else indirectly through
entrainment by steam or compressed air.
In cases where the path followed by the sealed containers to be
processed includes two parallel passageways crossed in opposite
directions, for instance, the jets may be given complementary
conical shapes between said passageways in order that they should
reach the entire area of the containers or that of the means used
to convey them.
In accordance with the present invention, where misting is used it
is preferable to impart to the cloud bathing said containers a very
active circulatory motion within the treatment chamber in order to
improve heat transfers and make the ambient atmosphere homogeneous
throughout the volume of the treatment chamber.
Another object of the invention is to provide apparatus for
performing this method, in which apparatus an endless conveyor
successively traverses downwardly a liquid pressure-column, a first
upwardly directed retrogression along the path, a treatment chamber
containing a liquid at a required temperature subjected to the
pressure of a gaseous fluid, a chamber in which said conveyor
follows a path which conducts it to a second upwardly directed
retrogression for exit into a liquid pressure-column and in which
are combined introducing and pressure-maintaining means for
introducing and maintaining said gas in said chamber and
temperature-maintaining means for maintaining said temperature of
said treatment liquid at a value such that the vapor pressure of
said liquid in said gas be less than said pressure.
In specific instances where a spraying of the liquid is used in
performing the method, it is highly advantageous for the
container-transporting receptacles, consisting of open-ended
cylindrical tubes, long pouches open in front, or angle irons, to
be perforated over their entire length or over all their faces in
order to permit a vertical streaming effect successively through
these conveyors.
The description which follows with reference to the accompanying
nonlimitative exemplary drawings will give a clear understanding of
how the invention can be carried into practice and will disclose
other advantageous features thereof which naturally fall within the
scope of the invention.
In the drawings,
FIG. 1 shows in schematic section a first form of embodiment of a
sterilizing apparatus according to the invention;
FIGS. 2 and 3 are alternative forms of embodiment thereof;
FIG. 4 shows, on an enlarged scale, a further alternative
embodiment in which the treatment chamber is provided with
substantially and essentially horizontal conveying paths;
FIG. 5 shows another constructional form similar to that of FIG. 4
but in which the conveyor loading and unloading station is located
at a level below that of the entrance and exit column heads, and in
which the entrances and exits of the sterilization chamber are
transferred to the same side of the apparatus;
FIG. 6 shows an alternative embodiment in which the entrance and
exit columns are fractionated;
FIG. 7 shows a first driving arrangement utilizing chains and
sprocket wheels adjustable on their hubs;
FIG. 8 is an alternative arrangement to that of FIG. 7, for use
with a transmission system utilizing gearwheels with verniers and
an adjustment jack;
FIG. 9 shows in schematic section an apparatus according to a
second form of embodiment of the invention;
FIGS. 10 and 11 are alternative embodiments thereof;
FIGS. 12 through 14 illustrate other alternative embodiments;
FIG. 15 is yet another alternative embodiment;
FIG. 16 shows in cross section a processing apparatus in which the
jets are staggered;
FIG. 17 is a section taken through the line XVII--XVII of FIG.
16;
FIG. 18 shows in similar fashion to FIG. 16 a section taken through
a misting apparatus utilizing a forced circulation of the mist;
and
FIG. 19 is a section taken through the line XIX--XIX of FIG.
18.
The sterilization apparatus shown in FIG. 1 comprises an entrance
water column 1 whose height corresponds to the required pressure
and at the base of which the conveyor chains 2 pass over idler
wheels 3 which turn the chains back upwardly along their path. The
base of the column 1 communicates with an entrance 4 whereat the
liquid of the column 1 is maintained at a lower level within a
space 5 in which prevails an air pressure maintaining the column
liquid at a level 6 close to the head of the column. The space 5
contains a further direction-reversing system of idler wheels 7
which turn the chains downwardly into a liquid contained in a
sterilization chamber 8 arranged within the apparatus itself,
between rising partitioning walls 9. Above the bottom of this
chamber is a further direction-reversing system 10 which causes the
conveyor to rise once more out of the liquid in the chamber 8.
Above the second wall 9 of this chamber, in the space 5, is another
direction-reversing system 11 which causes the conveyor to descend
and to pass through a liquid at the bottom of an exit column 12,
while a further direction-reversing system 13 leads the conveyor
beneath the internal wall of said column. Above the two columns are
positioned idlers 14, 15, whereby the conveyor is looped back onto
itself. Along the loop-closing path is located a station 16 for
loading and unloading the conveyor chains 2.
Referring next to FIG. 2, the bottom 17 of the entrance column 1a
constitutes the bottom of a space 18 which is surmounted by the
bottom 19 of a raised sterilization chamber 8a, and one of the
walls 9a of said chamber 8a separates the latter from a space 20
which is closed by a bottom surface 21 substantially level with the
bottom 19. Into this space 20 opens the foot of an exit column 12a
which is separated from the entrance column 1a only by a partition
22.
In such an arrangement the path followed by the conveyor includes a
descent into the column 1a, twin idler systems 3a, 3b in the space
18 followed by a horizontal path therebetween, an upward path past
the idler wheels 3b and along the length of the wall 9b of chamber
8a, a direction-reversing wheel system 7a above the head of the
partition 9b, a descending path into the sterilization chamber 8a
down to a bottom direction-reversing system 10 a, an ascending path
up to an exit direction-reversing system 11a, a descending path
down to a direction-reversing system 13a at the foot of the column
12a, an ascending path into said column 12a, followed by a passage
over a direction-reversing system 14a located above the partition
22 separating the columns 1a and 12a. A loading and unloading
station 16a is positioned above the heads of the columns beneath
the direction-reversing system 14a. For greater simplicity, all
direction-reversing or changing systems will hereinafter be
referred to as `idlers.` The space surmounting the sterilization
chamber 8a and the feet of the columns is closed, said space
containing the idlers 7a and 11a and containing air under pressure.
This air acts on the water level at the foot of the columns whereby
to maintain the upper level thereof at the required height.
In this form of embodiment the entrance and exit columns are
adjacent and located on the same side of the apparatus.
In the constructional form schematically illustrated in FIG. 3, the
apparatus is identical but the conveyor includes an external lower
offset loop enabling the loading and unloading station 16b to be
moved level with the bottom of the sterilization apparatus by means
of idlers 22, 23 positioned at the heads of the columns 1b and 12b
respectively. Beyond the idler 23 extends a horizontal path up to
an idler 24, whence the path extends vertically down to an idler
25. Ahead of the entrance idler 22 is a likewise vertical path
extending from a foot idler 26 level with the idler 25. These
idlers 265 and 26 flank a raised idler 27 beneath which is located
the loading and unloading station 16b.
The various dispositions hereinbefore described are devised in such
manner that the paths followed by the conveyor through the
sterilization chambers are vertical. FIG. 4, however, shows an
arrangement in which these paths are essentially horizontal.
Accordingly, the conveyor 2c descending through an entrance column
1c passes beneath an idler 3c before emerging into the offset part
of the foot of this column. It then passes over an idler 7c above
one of the partitions 9c bounding the sterilization chamber 8c
containing water enclosed in a sealed space 5c and subjected to the
pressurized air filling this space. Consecutive stepped idlers 10c
in the chamber 8c enable horizontal conveyor runs 28 to be formed,
while the last bottom idler 29 located in the corner diagonally
opposite the corner nearest the idler 7c enables the conveyor to be
led out vertically from the liquid in the chamber and to pass over
an exit idler 11c.
The conveyor then follows a descending path into a laterally
located column 30, and then passes through a tunnel 31 after
running over an idler 13b, said tunnel being arranged beneath the
chamber 8c. The conveyor then passes over an idler 13c at the foot
of the exit column 12c, which column is located adjacent the
entrance column 1c. An idler 14c at the head of the columns enables
the conveyor to be looped back onto itself, and beneath this idler
is disposed a loading and unloading station 16c.
Reference is now had to FIG. 5 for the illustration of an apparatus
of the same kind arranged in similar fashion to that of FIG. 4,
except for the provision of entrances and exits located on the same
side of the sterilization chamber and also of a baffle in the
tunnel beneath said chamber. A further exception is the transfer of
the loading and unloading station to a low level, by an arrangement
similar to that of FIG. 3.
Referring still to FIG. 5 for a more detailed description, this
particular constructional form comprises an entrance column 1d
below which an idler 3d guides the conveyor chains upwardly over
two spaced idlers 7d, 7e placed above and on either side of the
wall 9d bounding the sterilization chamber 8d. Above this wall is
likewise provided a single lower idler 11d which redirects the
emerging conveyor downwardly along the wall 9d. At the foot of this
downward path, in the midst of the liquid at the foot of the
entrance column 1d and in the offset part thereof, is located an
entrance idler 3f into a tunnel 31d having therein a baffle 32
facing which is located a bottom idler 3e which redirects the
conveyor towards an idler 13d paced at the bottom of the exit
column 12d. Above this column 12d is an idler 22d and above the
associated entrance column 1d is an idler 23d preceded by an idler
24d. The loop is closed between idler 24d and idler 22d via two
idlers 25d and 26d, between which is positioned a raised idler 27d
beneath which is located a loading and unloading station 16d, the
latter being thus relocated near the bottom of the apparatus,
approximately level with the supporting floor.
The pressurized air for pressurizing the water in the sterilization
chamber 8d is conveyed, through a pipe 33 equipped with a valve, to
the top of the chamber which closes the foot of the entrance column
1d, the water level at said foot being comprised between said
partition 9d in the lower part of the apparatus and a point near
the lower edge 34 of one of the dependent walls of the column 1d.
This edge automatically regulates the maximum air overpressure,
since excess air finds its way beneath the edge 34 and out through
the column 1d. This water level also constitutes the level which
ensures filling of the subjacent tunnel 31d and additionally forms,
by way of said tunnel, the level at the foot of the exit column
12d.
Considering now the methodical circulation of the water, a cold
water inlet 35 regulated by a thermostat valve and possibly also by
a constant-level float-valve is provided at the head of the exit
column 12d, as may likewise be the case for all the other
constructional forms described precedingly.
By a counterstreaming process, this cold water methodically cools
the emerging products travelling in the opposite direction, i.e.
ascending the exit column 12d. The gradually heated water passes
through the baffle-tunnel 31d and is hot when it reaches the foot
of the entrance column 1d. While still being counterstreamed, this
hot water is cooled in column 1d and at the same time preheats the
products descending therethrough on the conveyor 2d.
The water cooled thus spills from the column 1d by way of an upper
spillway 36 whose level regulates the required water pressure.
Because the intake of cold water into the exit column is adjusted
by a temperature-sensitive device such as a suitably located
adjustable thermostat, the ultimate cooling temperature on emerging
from the exit column 12d will invariably be below a specified
temperature.
In order to save water and heat and maintain the upper levels in
the pressure columns notwithstanding the wide variations often
occuring in the degree to which, for various external reasons, the
conveyor is loaded with objects to be processed, which cause the
loading and unloading station to be supplied nonuniformly,
compensation is made either for the often massive expulsions of
water which may occur following the transition from operation with
a lightly loaded conveyor 2d to operation under full load, or,
conversely, for the often massive intakes of cold water which could
occur through the inlet 35, by associating with the spillway 36 a
buffer tank 37 which is itself provided with an overflow 38.
With this tank is further associated an offtake pump 39 which draws
from the bottom of the tank and delivers through a nozzle 40
located above the column 1d. The pump 39 thus compensates for drops
in the level of the columns when, for instance, the conveyor is
loaded to less than its maximum capacity, whereby the level
corresponding to the correct overpressures in the apparatus is
restored, Moreover, the residual heat of this returning water is
not lost for warming up the products entering the apparatus.
Considering next the pressures, the water temperature in the
chamber 8d, as in the previous constructional forms described, is
maintained, by regulated steam-type heating means (not shown), at a
constant suitable value such that the steam pressure at that
temperature be less than the counterpressure exerted by the air and
which is given by the water column existing between the edge 34 and
the spillway 36, which two elements, in conjunction with the intake
35 to the pump 39, contribute toward maintaining this water column
height at a constant value.
Inside the tunnel 31d, the baffle 32 helps to correctly grade the
cooling temperatures of the products issuing from the chamber 8d,
by making use of the tendency resulting from variations in the
density of the circulating water. In the columns, on the contrary,
the density effect opposes such a grading, and this is offset by
making the columns as narrow as possible in order that the products
and the supporting receptacles therefor carried along by the
conveyor, in conjunction with the water circulation rate, produce a
water entrainment effect greater than that resulting from density
variations.
Since the overpressure to be obtained on the water in the
sterilization chamber may have to be great, the height of the
entrance and exit columns for the products to be processed could
become prohibitive. This is overcome by fractionating the height of
the columns and by inserting between the fractionated sections
compressed-air relay-columns, as shown in FIG. 6.
In the alternative constructional form shown in this figure, the
sterilization chamber exit tunnel is laid out differently from that
of FIG. 5. In FIG. 6, the latter portion of the tunnel passes above
the sterilization chamber. This in turn means that such a tunnel
must be made relatively narrow since the beneficial effects of the
water density variations no longer exist.
Another essential difference between the embodiments of FIGS. 5 and
6 is that the entrance column comprises a section 1e whose bottom
communicates with a relay-forming air column 1f the top of which in
turn communicates with the second column section 1g likewise filled
with water.
Similarly, the exit column comprises a first section 12e
communicating through its base with an air relay column 12f the top
of which in turn communicates with the second section 12g of the
exit column. This section 12g has its bottom connected to the upper
run of the exit tunnel 31g, and this tunnel communicates, via an
extension beneath the sterilization chamber 8e, with the base of
the column 1g.
The compressed air needed to obtain the required overpressure may
be introduced through a pipe 41, preferably very close to the water
level within the space bounded by the lower edge 34e of one of the
internal walls of column 1g and the top of the wall 9e of the
chamber 8e. This pressurized air can if necessary find its way
beneath the edge 34e into the internal space corresponding to the
relay column 1f. A balancing pipe 42 is connected across the heads
of relay columns 1f and 12f.
With such an arrangement the air overpressure is maintained
automatically constant and equal to the sum of the pressures
exerted by the water columns on the liquid in the chamber 8e, while
the two different pressure values required in the relay columns are
also maintained. The excess compressed air passes round the base of
the columns 1e or 12e and escapes from the heads of these
columns.
Considering next the water circulation, cold water can be admitted
through a pipe 43 in quantities regulated by a float-valve 44 which
ensures a constant level in the head of the second exit column
section 12e. At the foot of this section 12e is provided a pump 45
whose output is regulated by a thermostat-controlled valve 46 which
feeds a pipe 47 for introducing the required quantity of water in
the head of the exit column section 12g, such thermostatic control
enabling the desired temperature values and gradings in the column
12g and the tunnel 31g to be obtained. The water is thus
counterstreamed in the fractional sections of the exit column and
also through the tunnel 31g. This water also counterstream-feeds
the column 1g and, by overflowing from the head of column 1g into
column 1f, additionally supplies the column 1e, from which it can
overflow into a compensating tank 37e of the same kind as that
described with reference to FIG. 5. A pump 39e at the foot of the
tank restores the level in the head of column 1e via a delivery
pipe 40e. A second pump-equipped tank could be provided to ensure a
similar volumetric compensation into the top of the column 1g.
Obviously, the form of embodiment of FIG. 6 comprises the necessary
idlers at each change of conveyor direction, in similar fashion to
the constructional form described with reference to FIG. 5, with
additional idlers located at the extremities of the fractional
sections of the water and air relay columns.
Apparatus devised as described hereinabove require a total conveyor
length which can sometimes be considerable. For example, an
apparatus operating at 120.degree. C. in the sterilization chamber
with an overpressure of about 80 kPa will require entrance and exit
columns containing water to a height of approximately 20 meters
unless they are subdivided, though it will be appreciated that any
such subdivision will lengthen rather than shorten the total
conveyor path. For a sterilization time of about 20 minutes and an
hourly output of 300 containers, each containing about 120 grams of
a substance to be sterilized, the total conveyor length required
under such conditions would be about 140 meters.
With such a great length and correspondingly large number of
idlers, any attempt to drive the conveyor from a single point only
would involve exerting forces which neither the chains nor the
idler bearings could be expected to withstand if the cost of
building such an apparatus is to be kept within reasonable
limits.
It is therefore preferable to drive the conveyor simultaneously
from several different points in order to reduce the stresses set
up.
As shown in FIGS. 5, 7 and 8, the driving force which is applied,
say, to the shaft of the idler 27d acting as a principal drive unit
synchronized with the mechanisms of the loading and unloading
station 16d, is transmitted externally of the apparatus, through a
sprocket wheel 48 and a chain 49 to a sprocket wheel 50 rigid with
the shaft of the idler 11d at the exit of chamber 8d, thereby
forming a transmission interconnecting two shafts rotating in the
same direction.
If, however, it be desired to provide a mutual drive for two
adjacent idler shafts rotating in opposite directions, as is the
case for instance with the shafts of the exit and entrance column
head idlers 22d and 24d respectively, the said shafts may be
rigidly connected to externally meshing equal gearwheels 50 and 51.
One of these shafts may act as a driving member driven by the
conveyor chains themselves, in cases where the idlers are toothed
sprockets meshing positively with the chains. The shaft of the
second gearwheel is made rigid with similar sprockets whereby to
positively drive the conveyor chains running over them. In the
example of FIG. 5, the shafts of idlers 22d and 24d are independent
of the principal drive shaft of idler 27d, but it will be manifest
that a transmission other than that supplied by the conveyor chains
themselves could be used.
It will be of advantage to provide external transmission between a
main shaft and second drives, by distributing these secondary
drives uniformly over the length of the conveyor, while making due
allowance for the resistances encountered (which are greater along
horizontal paths) and for the number of idlers comprised between
the drive members.
Driving an endless conveyor at several points requires certain
precautions in order that the external drives and those transmitted
through the internal chains should not counteract one another as
the result, firstly, of possible irregularities in the various
chains sections and, secondly, of expansion effects due to passage
through parts of the apparatus raised to greatly differing
temperatures. It is therefor important to provide suitable
clearances and to determine precise settings on the idlers which
separate the various sections of the path and which act as drive
points.
In order to facilitate such adjustment yet avoid having to remove
the chains from the sprockets, the external drive wheels are
mounted in angularly adjustable manner on the corresponding shafts.
By way of example, the sprockets 48 and 50 interconnected by an
external chain 49 have hubs 52 and 53 which can be mounted
adjoining drive flanges keyed or welded to the shafts. The hubs and
the flanges have holes formed, therein, through which pins or studs
parallel to the shafts can be threaded. Such a flange may comprise,
for instance, a set of 20 regularly spaced holes and the hub 53 a
set of likewise regularly spaced holes 54, the two sets of holes
being located on circles of equal radius. With such an arrangement,
in which four of the holes on the hub 53 will always register with
four of the holes on the flange, the sprocket 50 can be made rigid
with its shaft by means of four bolts or pins, the angle between
two consecutive registerings being only one-eightieth of a
revolution. A quadruple vernier adjustment is extremely precise as
regards the respective positions of the internal conveyor chains
and the external drive chains, while at the same time permitting
secure attachment by four bolts. Different effects could be
obtained by providing single, double, triple, or more verniers.
As FIG. 8 clearly shows, there is interposed between the vernier
hub 55 of gearwheel 51 and the latter (which is loosely mounted on
its hub), an abutment 56 rigid with the hub 55, a lobe 57 rigid
with gearwheel 51, and a bolt 58 which is screwed into lobe 57 and
whose tip bears against the abutment 56. This makes it easy to
obtain a displacement of the wheel relative to its shaft in spite
of a possibly heavy load on the chains.
Moreover, such a long conveyor is necessarily subject to chain
elongation. In order to correct this defect it is preferable to
provide an elastically or nonelastically mounted tensioning idler
at least at one point along the chain length. FIG. 5 shows such a
movably mounted idler 25d coupled to elastic tensioning means and
additionally equipped with guiding means 59 of the conveyed
objects, mounted telescopically relative to the fixed conveyor
guides.
Manifestly, the various arrangements according to the invention
hereinbefore described can be executed with any convenient conveyor
system. In order to achieve the large throughputs required, the
conveyors generally consist of two parallel endless chains
interconnected by means of container-carrying receptacles bearing
the products to be processed, or by means of sectional-iron
supports forming socketlike receptacles into which the containers
are inserted and from which they can be withdrawn subsequent to
processing. Preferably, such a conveyor consists of two parallel
endless chains equipped with thrust pegs which entrain, along a
path coextensive with said chains, tubular receptacles into which
said containers containing the products to be processed are
inserted and subsequently extracted, said receptacles preferably
not being attached to said chains.
These receptacles are preferably cylindrical which, by virtue of
their being independent of the chains, enables them to revolve
about themselves along the horizontal path sections, such as those
provided in the sterilization chamber 8d, for instance. This
autorotation of the receptacles produces a rotation of the
containers themselves, which greatly improves the effectiveness of
the heat treatment in a great many cases.
It goes without saying that should such container rotation prove a
drawback with certain types of product, preference must be given to
apparatus having exclusively vertical paths through the treatment
chambers, or else steps must be taken to rigidly interconnect the
conveyor and the receptacles in order to prevent any detrimental
agitation.
Thus food and pharmaceutical or other products can be processed in
this way, an example being children's food, the processing being
performed in glass, tin, aluminum or plastic containers of smaller
thickness than usual and which comprise sealing means which, though
entirely capable of withstanding an internal vacuum for sealing
purposes, may or may not be capable of withstanding an internal
compression.
The apparatus illustrated in FIG. 9 is of a disposition similar to
that of the apparatus of FIG. 1, like parts being designated by
like reference numerals. In the apparatus of FIG. 9, however, the
liquid level in the column 8 formed inside the treatment space is
located right at the bottom of the column, from which a pump 60
draws said liquid (water, for example) and conveys it through a
riser 61 into gutters 62 located at the top of the riser, said
gutters being provided with spillways which spread the streaming
water over the entire width of said riser. The spillways may be
supplemented if necessary by spraying effected by means of nozzles
63 suitably spaced along the riser 61. Depending on the fineness of
the droplets, these nozzles may provide ordinary spraying, misting,
or atomization, and any one of these results can be obtained by the
use of means well known per se.
The gas under pressure air, for example is admitted through an
inlet 33 located in the roof of the chamber 8 and its ancillaries.
This pressurized gas maintains the chamber 8 at a pressure equal to
the height of the column of liquid located above the edge 34 of the
wall bounding the space 4 adjacent the chamber 8, and any excess
compressed air can pass beneath this edge 34 and out through the
column 1 into the surrounding atmosphere after passing through the
upper level 6 of the water contained in said column. Such a
disposition consequently provides autoregulation of the
pressure.
The water temperature at the foot of column 8 is maintained by heat
exchanger means (not shown) for which the heat supply is governed
by a thermostat-regulator of any convenient type (not shown). This
temperature is so regulated that the vapor of the liquid, at the
temperature in question, be at a pressure below the air pressure
maintained in the chamber.
It will be seen that with such an arrangement the height of the
column 8 can be as large as desired, the water level at the bottom
being relatively low, and that the walls 9 can be as high as
necessary. The time taken by the conveyor 2 to pass through the
chamber 8 is therefore longer. This means that the sterilization
treatment is made more thorough without the need to reduce the
conveyor speed. The thermal efficiency is augmented as regards the
heat transfer between the water spray issuing from the nozzles 63
and the walls of the containers to be processed. These walls may be
sprayed from beneath the spillways of the gutters 62, which gutters
lie in the planes of the ascending and descending runs of the
conveyor. These sprays impinging on the containers agitate the
latter, which further assists the processing in certain cases. To
that end the spray jets are made powerful enough to move the
containers in their receptacles as they pass along, adequate
clearance being naturally provided therein for the purpose.
The form of embodiment shown in FIG. 10 differs from that of FIG. 9
chiefly by the suppression of the upwardly located idlers 7 and 11
and by the consequent reduction in volume of such intermediate
spaces as the space 4. On the other hand, the pressurized chamber
8f used for the processing is shaped as a bell upturned above an
open vat 9f.
This being so, the edge 34f of the chamber 8f will enable the
compressed air to pass into spaces 5f and 5g whereat meet the feet
of the entrance and exit columns 1 and 12 which are positioned on
either side of the walls 9g and 9h of the vat 9f, with downwardly
dipping edges 34g and 34h respectively. The compressed air is also
able to pass beneath these edges 34g and 34h and out into the open
atmosphere by passing up the columns 1 and 12. Thus, in this case
also the pressure is regulated automatically in the chamber 8f.
The spaces 5f and 5g are interconnected via an air pipe 5h in order
to ensure balanced pressures. In the spaces 5f and 5g are provided
two downward-directing idlers 7f and 7g and, in the vat 9f, two
upward-directing idlers 10f and 10g. A downward-directing idler 10h
is provided at the top of the bell 8f. A riser 61a equipped with
atomizers 63a is located within the bell 8f, above a pump 60a
drawing water from the vat 9f.
The embodiment shown in FIG. 11 is a simplified constructional form
which entirely eliminates the idlers 7, 7f and 7g of the previously
described forms of embodiment.
Accordingly, the treatment chamber 8i is of bell shape and located
above a space 9i which at the same time constitutes the feet of the
entrance and exit columns 1 and 12. In this space is arranged a vat
9j of suitably heated water from which the pump 60i draws. This
pump delivers the water into a riser 61i equipped with spray jets
63i. This riser divides into two upper branches 62i which are
equipped with spray jets directed at the conveyor around the upper
idler 10i positioned at the top of said space 8i.
In order to avoid overactive heat exchanges between the heated
water in the vat 9j and the feet of the columns, the water level is
established below the edges of said vat but above the edges 34i of
the feet of the columns. To this end also, since the level at the
foot of the columns must be kept above the edge 34i, this level as
well as the air pressure in the space 8i are regulated by a float
mechanism 34j which operates a valve in the air inlet 33.
FIG. 12 shows a sterilizer of known type utilizing a conveyor 2 of
the type in which tubular receptacles are entrained by two parallel
chains through an entrance column 1, a sterilization space 8k and
an exit column 12.
On issuing from the column 12 the conveyor passes into a
supercooling tank 12k having a wall 12l beneath which the conveyor
passes. The water circuit is so devised that it be supplied through
the column 12 and be discharged through the column 1 and that it
circulates in the opposite direction to the conveyor. At the foot
of the chamber 8k is placed a vat 9k beneath which is left a
passageway 65 through which the water passes without too
unfavorable a heat transfer taking place with the water used at the
foot of the sterilization chamber. The arrangement used for heating
the vat 9k is similar to that described precedingly, i.e. by means
of a heat exchanger and a thermostat, while the spraying system is
identical to that shown in FIG. 11. Similarly, the water level is
maintained by means of a float 34k, positioned in similar
fashion.
Reference is next had to FIG. 13 for the illustration of a
sterilizer which utilizes joists 64 for conveying the containers,
these joists being fixed to two parallel chains constituting the
conveyor 2. Said joists jointly form sockets on either side of the
plane containing the chains, and these sockets are caused to open
through the chains alternately passing over staggered pulleys 16a,
16b around which the chains wrap to a sufficient extent to cause
the two openings formed by each pair of cooperating joists to gape
open consecutively. The configuration of the sterilizer is similar
to that shown in FIG. 11, but in the example of FIG. 13 the
spraying takes place in the treatment chamber 8l by means of triple
spray pipes, due to the fact that the conveyor undergoes three
direction reversals in said chamber and comprises four separate
runs therein.
The final cooling can also be effected in a special column 65
adjacent the exit column 12l, said column being located above a
collector vat 66 positioned beneath the apparatus, and into said
column 65 have port spray jets 67 which spray the corresponding
conveyor run, these spray jets being supplied through a pipe 68
connected to the delivery end of a pump 69 drawing water from the
vat 66.
The apparatus shown in FIG. 14 comprises a conveyor 2 with which
cooperate container-conveying receptacles 70 of the type commonly
used in bottle-washing machines and which are loaded and unloaded
from the front at a station 16m.
The transformer which permits operation under pneumohydrostatic
overpressure includes a recirculating and spraying pump 60m which
draws the heated water from a vat 9m at the foot of the treatment
chamber 8m and which delivers it into a spray pipe 63m, compressed
air being admitted through an upper inlet 33 and the pressure being
modulated by a float 64m, as described precedingly.
Next to the treatment chamber 8m is provided a similarly arranged
cooling chamber 8n in conjunction with a pump 60n and spray pipes
63n. This chamber 8n communicates with the base of an exit column
12m to which adjoins a supercooling column 65m similar to that
described precedingly and in which the spraying is effected through
the agency of a pump 69m drawing water from a bottom vat 66m. Thus
cooling is effected by spraying into the column 8n, at the same
pressure as in the sterilization column 8m. The air pressure is
balanced by a pipe 8t interconnecting these two columns.
The cooling water is circulated via a bypass 70a on the delivery
side of the pump 69m, with subsequent discharge through a nozzle 73
above the column 12m. The flow is adjusted by a thermostat 72 which
measures the water temperature at the foot of the column 12m and
actuates the valve 71 at the entrance into the bypass 70a. The
cooling water flows from the column 12m to the column 1m beneath
the vat 9m.
Referring to FIG. 15, there is shown thereon an apparatus whose
conveyor 2 uses tubular receptacles which are loaded and unloaded
sideways at a station 16p, as described previously. This apparatus
comprises two entrance and exit hydrostatic columns 1p and 12p,
respectively, associated with preheating and precooling hydrostatic
columns 1q and 12q. Likewise provided is a treatment chamber 8p
within which the conveyor sustains several reversals of direction.
Also provided is a spray-type cooling chamber 8q. A spray-type
supercooling column 65p is likewise provided as precedingly and,
downstream of this column, the conveyor passes through a
water-containing tunnel 74 which extends beneath the apparatus and
which leads the conveyor to the station 16p.
A pump 69p recycles the water from the base of the tunnel 74 to the
top of the column 12p by bypassing the spray circuit through the
column 65p, as described precedingly, a similar regulating system
being provided by a valve 71p and a thermostat 72p. An additional
pump 75 is provided to draw water from the foot of the column 12p
and convey it to the top of the column 12q, in conjunction with a
further pump 76 which draws the water overflowing from the column
1p into a vat 77 and conveys it to a nozzle 78 adjacent the nozzle
73p.
This ensures that the volumetric compensation and cooling water
circulation functions are performed in the manner hereinbefore
described.
As regards air pressure balancing, the distribution is ensured
through a pipe 33p equipped with a valve 81 for intake into the
chamber 8p. The pressures in the chambers 8p and 8q are balanced by
a pipe 8r. Downstream of the valve 81 is provided a takeoff which
comprises a valve 79 and from which air is conveyed into the space
separating the foot of column 1p and the head of column 1q. The
pipe 80 balances the pressures between this space and the space
separating the head of column 12q from the foot of column 12p.
The valve 81 is actuated by a float 64p located between the heating
vat 9p and the foot of column 1q. The valve 79 can be reduced to a
simple calibrated jet, since any excess air in said column
separating spaces can be discharged automatically through the feet
of the end columns.
Obviously, pumps 60p and 60q which are counterparts of the pumps
60m and 60n, respectively, referred to precedingly, perform like
functions.
In all the constructional forms described hereinabove with
reference to FIG. 9 through 15, the disposition, orientation and
delivery force of the spraying, misting or atomizing jets, with
respect to the processed container, may be made such tat the latter
receive, as they move along, agitating impulses which assist the
processing and especially the heat transfer between the walls and
the contents of the containers.
As FIG. 16 clearly shows, the treatment chamber 100 flanked by the
overpressure columns 101 and 102 filled with the liquid forming a
sealing and pressure-boosting means, provides a passage for the
conveyor means 103 of the receptacles 104 bearing the sealed
containers to be processed along a path which is ascending on one
side and descending on the other.
At the foot of the chamber 100 is placed a liquid receptacle 105
whose base communicates through a pipe 106 with a pump 107. The
delivery pipe 108 of this pump divides into two branches 109 and
110, which branches form staggered injector banks 111 and 112
disposed along the opposite faces of the chamber 100 (see FIG.
17).
The injectors 111 are designed in such manner that they emit
conical jets whose apex angles are such that adjacent and opposed
projection layers be substantially tangential, as shown in FIG.
17.
Moreover, these jets 111 and 112 lie in the same vertical plane,
which plane is the plane of symmetry with respect to the two runs
of the conveyor 103 through the chamber 100.
In this chamber set under overpressure, therefore, the processing
liquid expelled through the jets is susceptible of reaching almost
the entire surface of the containers to be processed, as the result
of multiple impacts which are favorable to a homogeneous treatment
in conjunction with a highly active heat exchange coefficient.
Should only a single conveyor run be utilized, then instead of
conical jets it would be preferable to use flat jets which, through
staggered, will nevertheless cover virtually the entire surface of
the containers to be processed or of the receptacles containing the
same.
Manifestly, the spraying can be obtained mechanically or
pneumatically, using steam or compressed air.
Reference to FIGS. 18 and 19 shows that when a treatment chamber
113 set under an overpressure is subjected to internal misting, it
is preferable to associate with such a chamber a recirculating
system by means of a fan 114 which draws the mist through a suction
orifice 115 at the bottom of the chamber and impels it through a
tube 116 and a reentry orifice 117 into the chamber 113 near the
top thereof, whereby to obtain an active circulation of the
atmosphere and the mist contained in the chamber, while at the same
time rendering the ambient atmosphere in the internal space as
homogeneous as possible, with the same advantages as hereinbefore
cited.
This circulation can also be taken advantage of to bring in the
steam required to create the mist, through a nozzle 118 which, in
conjunction with the orifice 117, forms an ejectorlike device which
assists the recycling process.
As may be seen from FIGS. 17 and 19, in which the conveyor
receptacles illustrated are vertically moving tubular baskets
perforated over their entire length and periphery, the treatment
water streams from one to the other in succession and thus has
maximum effectiveness.
It goes without saying that many modifications may be made to the
specific embodiments described hereinabove without departing from
the spirit and scope of the invention. By way of example, a single
pressure column could be provided and could serve for both
introducing and withdrawing the products to be processed.
Similarly, fluids other than air and water could be used and, if a
complex processing is involved, a plurality of chambers could be
provided and be traversed in succession. Lastly, as shown in FIG.
5, the water in the sterilization chamber could be agitated by
means of a pump 60 which draws water at a low level and delivers it
through a pipe 61 to a higher level.
* * * * *