U.S. patent application number 09/907622 was filed with the patent office on 2002-03-14 for apparatus for heating and controlling the process temperature in a tunnel pasteurizer.
Invention is credited to Panella, Graziano, Pasoli, Giorgio.
Application Number | 20020031587 09/907622 |
Document ID | / |
Family ID | 11461870 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020031587 |
Kind Code |
A1 |
Panella, Graziano ; et
al. |
March 14, 2002 |
Apparatus for heating and controlling the process temperature in a
tunnel pasteurizer
Abstract
An apparatus for heating and controlling the process temperature
in a tunnel pasteurizer, in particular for packaged food products,
in which the tunnel, provided with a conveyor able to advance the
product, is substantially subdivided into a first pre-heating area,
into a second pasteurization heat treatment area and a third area
where the product is cooled. The apparatus is provided at least
with a heat exchanger comprising a primary loop and a plurality of
secondary loops, each of which is connected to the hydraulic loop
of each sub-area. Each secondary loop is further provided with
servo-controlled modulating valves which serve as means for
controlling the temperature of the water of the sprinkler of each
sub-area.
Inventors: |
Panella, Graziano;
(Grezzana, IT) ; Pasoli, Giorgio; (Verona,
IT) |
Correspondence
Address: |
BROWDY AND NEIMARK, P.L.L.C.
624 NINTH STREET, NW
SUITE 300
WASHINGTON
DC
20001-5303
US
|
Family ID: |
11461870 |
Appl. No.: |
09/907622 |
Filed: |
July 19, 2001 |
Current U.S.
Class: |
426/521 ; 99/330;
99/468 |
Current CPC
Class: |
A23L 3/003 20130101;
A61L 2/04 20130101; A23L 3/04 20130101 |
Class at
Publication: |
426/521 ; 99/468;
99/330 |
International
Class: |
A23C 003/02; A23L
001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2000 |
IT |
IT-VR2000A000077 |
Claims
What is claimed:
1. An apparatus for heating and controlling the process temperature
in a tunnel pasteurizer, in particular for packaged food products,
wherein the tunnel, provided with a conveyor able to advance the
product, is substantially subdivided into a first pre-heating area,
into a second pasteurization heat treatment area and into a third
area where the product is cooled, said first, second and third area
being considered each subdivided, in their length, into two or more
thermally independent elementary sub-areas each of which comprising
a hydraulic loop which allows to spray, with water at pre-set
temperature, the packaged product, which hydraulic loop in turn
comprises a sprinkler, and underlying collection tank and a
pipeline connecting the collection tank with the sprinkler, said
apparatus being provided at least with one heat exchanger
comprising at least a primary loop and a plurality of secondary
loops, each of said secondary loops being connected to said
hydraulic loop of each said sub-area, each said secondary loop
being provided with means for controlling the temperature of the
water of the sprinkler comprised in said hydraulic loop of each
sub-area.
2. An apparatus as claimed in claim 1, wherein said means for
controlling the water temperature are constituted by
servo-controlled low pressure modulating valves.
3. An apparatus as claimed in claim 1, wherein said first
pre-heating area and said second pasteurization heat treatment area
are each provided with said heat exchanger, the secondary loops of
each said heat exchanger being connected to the corresponding
hydraulic loops of said first pre-heating area and of said second
pasteurization heat treatment area.
4. An apparatus as claimed in claim 1, wherein said pipeline,
connecting the collection tank with the sprinkler in a sub-area of
said first pre-heating area, collects the water of said collection
tank and sends it to a sprinkler located in a sub-area of said
third cooling area and, from the collection tank associated to the
latter sprayer, returns it to the sprinkler of the sub-area of said
first pre-heating area.
5. An apparatus as claimed in claim 1, wherein the fluid
circulating in said primary loop of the heat exchanger is dry
saturated steam.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an apparatus for heating
and controlling the process temperature of a tunnel pasteurizer, in
particular for packaged food products.
[0002] As is well known, pasteurization of packaged food products
is the heat treatment whereto are subjected some types of products
already packaged in final containers, in order to improve their
preservation over time.
[0003] The type of pasteurization referred to hereinafter is "low
temperature pasteurization" and with specific reference to food
products constituted by drinks. This means that it takes place at a
temperature lower than 90.degree. C. by means of hot water which is
sprayed in a programmed manner onto the containers in order to
modify their temperature according to a defined thermal cycle.
[0004] The apparatus whereby the pasteurization process is achieved
is essentially constituted by a tunnel through which is treated the
product already packaged in the containers (bottles, cans or other
containers) which are made to advance in the tunnel by means of a
conveyor.
[0005] From the thermal point of view, the tunnel is essentially
subdivided into three areas: a first area (area 1) for pre-heating,
where the temperature of the product is increased to a value beyond
which the actual heat treatment takes place; a second area (area 2)
for heat treatment; a third area (area 3) for cooling, where the
product is brought back roughly to ambient temperature in order to
prevent undesired fermentation phenomena.
[0006] Each of these three area is further subdivided into two or
more parts (sub-areas) in order to: (a) avoid thermal shocks and
have the opportunity to recover heat between the heating and the
cooling areas, or (b) have available areas at different
temperatures, variable according to determined logic criteria, in
the portion of the tunnel where the actual heat treatment takes
place.
[0007] In accordance with the prior art, the heating of the water
that is sprayed onto the product (process water) takes place by
means of a plurality of heat exchangers, whereof each is associated
to a sub-area of the areas 1, 2, 3 into which the tunnel is
subdivided.
[0008] FIG. 3 shows a tunnel pasteurizer obtained according to the
prior art in question (see also patent EP 960 574),
[0009] Each of said exchangers is formed by a single primary loop,
whose fluid can be, depending on requirements, saturated steam,
superheated water, hot water, etcetera, and by a single secondary
loop wherein the process water circulates. Also present is a
metering valve for the primary circuit and a condensation drain if
the primary fluid is steam.
[0010] The process water circulates in each sub-area, through a
hydraulic loop connecting the collection tank, located below the
sprayed product, with sprinklers positioned above the product. The
secondary loop of each heat exchanger is connected with the
hydraulic loop of each sub-area, described above. To each sub-area
of the pasteurizer, whose process water requires appropriate
heating, must therefore be associated a specific heat
exchanger.
[0011] While this constructive solution meets the operating
requirements of the system very well, it does nonetheless have some
drawbacks.
[0012] These are, essentially:
[0013] A relatively great complexity of the system for controlling
and adjusting temperatures and hydraulic lines;
[0014] The need to provide for the maintenance of a high number of
heat exchangers and of the equally numerous high pressure metering
valves;
[0015] The inertia of the adjusting and controlling organs which
are subject to continuous disposition variations;
[0016] The poor efficiency of the heat exchangers which are often
called to operate in transient states.
[0017] To solve these series of drawbacks, some manufacturers have
adopted a centralized heating system, which provides for the
adoption of a single heat exchanger for all areas subjected to
temperature control. This exchanger provides for heating a mass of
water present inside a tank, which is maintained at sufficiently
high temperature, and which is mixed with the process water of the
various areas, in order to increase its temperature, depending on
the need of each. Thermal energy is thus distributed by means of
masses of hot water which are added in the areas where a
temperature increase is required.
[0018] FIG. 2 schematically shows a tunnel pasteurizer obtained in
accordance with this second type of prior art (see for instance
patent WO 95/22352). This technical solution, while providing some
unquestionable advantages over its prior art, still exhibits some
drawbacks.
[0019] In particular:
[0020] High quantities of water masses inside the pasteurizer which
must be heated before starting the conveyor (water masses present
both in the process vats and in the common tank) with evident high
energy expenditure;
[0021] Inevitable loss, at the final shut down of the pasteurizer,
of the energy expended for the preventive heating of the water mass
contained in the common tank;
[0022] Need for high water flow rates between the common tank and
the various process vats if the temperature of the water in the
common tank decreases (transferred power is equal to the product
between water volume and temperature);
[0023] The existence of a single heat exchanger which, during the
critical process control phases, must provide sufficient thermal
energy both for the rapid heating of the areas of the pasteurizer,
and for restoring the temperature of the water mass present in the
common tank. And this with the eventuality that it may not be
possible to perform the pasteurization process correctly and/or
completely, with the consequent possible spoiling of the
product;
[0024] The presence, inside the pasteurizer, of a great quantity of
water at high temperature concentrated in a single area (the common
tank) can alter, due to the heat exchange with the surrounding
environment, the thermal equilibrium of the areas subject to
temperature control;
[0025] The constant mixing of the water masses at different
temperatures in the different areas of the pasteurizer requires the
constant restoration of operating temperatures, once again with
great energy expenditure.
SUMMARY OF THE INVENTION
[0026] The essential aim of the present invention therefore is to
overcome the aforementioned drawbacks, relating to current systems
for heating and controlling the process temperatures in tunnel
pasteurizers, making available an apparatus that allows:
[0027] considerably to limit the number of heat exchangers used and
the fluid regulating sets in their primary loop;
[0028] to limit the frequency of the variations in heat power
supplied by the heat exchangers;
[0029] to maintain the process waters always separated from area to
the other of the pasteurizer;
[0030] to avoid the use of a common tank containing large
quantities of water at high temperature;
[0031] to simplify the structure of the hydraulic system of the
pasteurizer.
[0032] These aims and others besides are all achieved by the
subject apparatus for heating and controlling the process
temperature, whose main characteristics are indicated in the claims
that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Additional characteristics and advantages of the present
invention shall become more readily apparent from the detailed
description that follows of an embodiment of the apparatus in
question illustrated, purely by way of non limiting example, in the
accompanying drawings.
[0034] FIG. 1 shows a first example of prior art as previously
described;
[0035] FIG. 2 shows a second example of prior art also as
previously described;
[0036] FIG. 3 schematically shows the hydraulic loops and the
organs for heating and controlling the process temperatures
relating to the apparatus of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] With reference to FIG. 3, the tunnel of the pasteurizer,
which is provided with a conveyor (not shown) for advancing the
product according to the direction indicated by the arrow shown in
FIG. 3, is subdivided into three areas, i.e.: a first pre-heating
area 1 which is subdivided (in the example shown) into four
thermally independent elementary sub-areas 11, 12, 13, 14; a second
area 2 for the pasteurizing heat treatment, which is subdivided
(again with reference to the illustrated example) into three
thermally independent sub-areas 21, 22, 23; a third cooling area 3
which is subdivided (also with reference to the illustrated
example) into four elementary sub-areas 31, 32, 33, 34.
[0038] A suitable apparatus for measuring and processing data is
able to measure and record process water temperature and to
determine, by mathematical calculation, the temperature of the
product in each of the elementary portions (sub-areas). Said
apparatus is not shown in the accompanying drawings because it is
known in itself (it is constituted by probes connected to a
computer). Nor is its exact positioning shown (which in any case
has to be in the areas or sub-areas of interest) because it depends
on the various functional and operative requirements. Measured and
recorded temperature values are constantly compared with set values
(i.e. pre-determined values) defined for a characteristic point of
each of the elementary sub-areas of the areas 1, 2 and 3 into which
the tunnel is subdivided. Such an apparatus for computerized
adjustment and control is, in any case, described in patent EP 960
574.
[0039] Again with reference to FIG. 3, the apparatus for heating
and controlling the process temperature shall now be described.
[0040] Each elementary sub-area of the pre-heating area 1 and of
the area 2 for the pasteurizing heat treatment comprises a
hydraulic loop 3 which allows to spray, with process water at
predetermined temperature, the packaged product in transit on the
conveyor.
[0041] With reference to the pasteurizing area 2, each hydraulic
loop 3 in turn comprises a sprinkler 4, an underlying collection
tank 5 and a pipeline 6 connecting the tank 5 with the sprinkler
4.
[0042] Note that, with reference to the pre-heating area 1, the
pipeline 6 that connects the tank 5 with the sprinkler 4 extends
its route to the cooling area 3. Starting from the tank 5, for
instance of the sub-area 14, the pipeline 6 feeds the upper
sprinkler of the sub-area 31 and hence the water drained from the
tank of this sub-area 31 returns towards the sprinkler 4 of the
sub-area 14. For the sake of descriptive simplicity the entire
pipeline connecting the sub-areas 14 and 31 has been indicated with
the same reference number 6 as the other similar pipelines.
[0043] Obviously, this holds true also for the other sub-areas 11,
12, 13 and 32, 33, 34.
[0044] According to the embodiment illustrated in FIG. 3, the
apparatus of the present invention comprises two heat exchangers 7
associated respectively to the first pre-heating area 1 and to the
second pasteurization heat treatment area 2.
[0045] Each exchanger 7 comprises a primary loop 8 (whereto are
associated a metering valve 15 and a condensation drain 16) and a
plurality of secondary loops 9 (as many as there are elementary
sub-areas in which heated process water is present-this is not the
case for sub-area 11). Each of the secondary loops is connected to
the hydraulic loop 3 of each elementary sub-area.
[0046] More specifically, each loop 9 is fed in the lower part of
the loop 3 by the process water coming from the tank 5 and ends in
the upper part upstream of the sprinkler 4.
[0047] Each secondary circuit 9 is also provided with means for
controlling the water temperature of the related sprinkler 4 which
are constituted by a servo-controlled modulating low pressure valve
10 positioned, on the loop 9, upstream of the sprinkler 4.
[0048] The injection, or lack thereof, of process water (at a
temperature deriving from the heat exchange in the exchanger 7)
from the loop 9 to the hydraulic loop 3 determines the temperature
variation of the water sprinkled by the sprinkler 4. This variation
is a function of the water temperature in the circuit 9 downstream
of the exchanger 7 and of the water flow rate injected downstream
of the valve 10. Note that the use of loops 7 with multiple
secondary loops 9 allows to maintain constantly active the system
for adjusting the primary loop 8. And this thanks to the
probability of energy demand by at least one of the secondary loops
9.
[0049] This fact allows:
[0050] both to reduce the inertia of regulating organs which from a
state of inactivity were required suddenly to output maximum power,
since it is likely that at least one of the elementary sub-areas
served by the same exchanger 7 requires energy delivery at
different times or at the same time;
[0051] and to have a good efficiency of the exchanger 7 and of the
modulating valve 10 because their working range varies within
contained values.
[0052] Note also that if in the primary loop 8 of the heat
exchanger 7 the fluid were constituted by dry saturated steam, the
assembly formed by metering valve 15 and condensation drain 16
would become self-regulating.
[0053] In this case the valve 15, the exchanger 7 and the
condensation drain 16 would respectively become a pressure
regulator 15 (the pressure of the dry saturated steam), a condenser
7 and a condensation drain 16. This means that, as long as in the
secondary loops 9 circulates water that cools the steam present in
the primary circuit 8 making it condense, the condensation drain 16
opens to make the condensation flow out in a quantity proportional
to the heat exchanged and the pressure regulator (valve 15) opens
to restore the value of pressure whereto it is calibrated. When the
steam in the loop 8 is no longer cooled by any secondary fluid, no
condensation being formed, the drain 16 closes, the pressure
downstream of the pressure regulating valve 15 increases, and the
valve itself shuts off the flow of steam.
[0054] Since the formation and evacuation of condensation is
proportional to the heat removed from the water which may circulate
in the secondary loops, the pressure variation of the steam in the
condenser (heat exchanger 7) is proportional to the quantity of
condensation evacuated, and the opening of the pressure regulating
valve 15 is proportional to the pressure downstream thereof, the
flow of steam in the primary loop 8 of the exchanger 7 is
consequently regulated automatically as a function of the heat
removed.
[0055] Obviously the present invention may assume, in its practical
realization, different configurations from the one illustrated
above, without thereby departing from the scope of protection of
the present monopoly.
* * * * *