Spray type retort sterilizer

This invention relates to a spray type retort sterilizer which preforms various types of high-pressure sterilization. Sterilization is achieved through the use of non-atomized hot water droplets. The sterilized comprises a retort that is capable of receiving multiple trays of materials, a pressurized air intake system for introducing pressurized air into the retort, an exhaust system and multiple spray units capable of spraying liquid such that at least one spray unit is disposed adjacent to each tray of material. The invention is further defined to include a heat exchanger and a pump for removing the liquid from the retort, passing it through the heat exchanger and delivering the liquid to the spray units. The invention is further defined to include spray units that are rotatable.

BACKGROUND OF THE INVENTION 
This invention relates to a spray type retort sterilizer, and more 
particularly a spray type retort sterilizer which performs various kinds 
of high-pressure sterilization of gas foods containing a lot of gas, 
transfusion soft pack for medicine, etc. Conventionally, various kinds of 
device which performs pressurized heat sterilization by using either a 
steam type or a hot-water type retort have been put into practice as 
retort sterilizer. Such devices are described in the Japanese Bulletins of 
Publicized Patent No. 58-57146 and No. 58-57147, for example. 
In the steam type retort sterilizer, the object material to be sterilized 
is placed in the retort by loading the material on trays and stacking 
these trays. The steam outlet is designed in most cases in such a way that 
the steam may be discharged from the bottom of the retort toward the top. 
As a result, it was often the case that the object material placed on the 
trays at the lower part is heated at a proper temperature while the object 
material placed on the trays at the top part remains in the state of 
uneven sterilization due to a drop of temperature of the steam as it rises 
through the retort. 
Moreover, a hot-water type retort presented a problem in that the object 
material stored in the trays gets unstable under the influence of the 
buoyancy of the hot water, requiring a complicated construction having a 
presser lid for the trays. The influence of the buoyancy was particularly 
large in the case of gas foods, while a problem with transfusion soft pack 
for medicine, etc. is that the very act of submerging the material in hot 
water is undesirable. 
This inventor proposed, in the Japanese Utility Model Gazettes No. 
63-16519, No. 64-19436, No. 64-19437, No. 64-19438 and No. 64-20849, a 
retort sterilizer which, though of steam type, can solve the above 
problems and enable even sterilization of the object material in the trays 
with fine mist sprayed from spray nozzles provided on header pipes which 
are installed vertically or horizontally at positions close to the tray of 
each stage. 
By the way, in the retort sterilizer already proposed by this inventor, 
etc., hot water is sprayed on the object material in hot water drops of a 
particle size of 0.2.about.0.6 mm or so (in the shape of sesame particle). 
In that case, hot water drops of a particle size of 100.degree. C. hot 
water sprayed from the nozzles instantly turn into steam by boiling and 
cannot be sprayed on the object material in the desired state of hot water 
drops if the internal pressure of the sealed retort is equal to the 
atmospheric pressure, for example. If you increase the size of the hot 
water drops, for example, to prevent such boiling phenomenon, those hot 
water drops cannot be sprayed to distant points. On the contrary, if you 
increase the spraying force to make the hot water drops go further, it 
leads to either breaking of the plastic pack containing the object 
material i.e. the material to be sterilized or deformation of the pack. 
Namely, the above-mentioned problem is produced as a result of softening 
of the plastic pack itself with the heat inside the retort. 
This invention has been proposed, therefore, in view of the above problem 
and its object is to provide a retort sterilizer which does not produce 
any atomization by boiling in the retort even if the particle size of the 
hot water drops is 0.2.about.0.6 mm and the hot water temperature is 
90.degree..about.130.degree. C. 
BRIEF SUMMARY OF THE INVENTION 
The technical means to achieve the said object consists, of a retort 
sterilizer provided with a retort of sealed construction in which trays 
loaded with the object material to be treated are stacked in a plural 
number of stages, spray units which emit hot water or cooling water on the 
object material on the tray in each stage inside the retort and a 
circulation route through which to blow the water accumulated at the 
bottom of the retort in the form of mist from the spray units again under 
pressure through a pump and a heat exchanger. The present invention also 
includes an internal pressure adjusting system composed of a pressurized 
air intake system which introduces pressurized air into the retort and an 
exhaust system which evacuates gas from inside the retort. 
In a spray type retort sterilizer according to this invention, the internal 
pressure of the sealed retort is set at a pressure at which the desired 
hot water drops are not instantly atomized by boiling with mutual 
operations of the pressurized air intake system which introduces 
pressurized air into the retort and the exhaust system which evacuates gas 
from inside the retort. Therefore, even with hot water of a temperature of 
90.degree..about.130.degree. C., it is possible to blow hot water drops of 
a particle size of 0.2.about.0.6 mm uniformly against the object material 
and equalize the temperature in the entire area of spraying to ensure a 
treatment of high efficiency. 
With a spray type retort sterilizer according to this invention, provided 
with a pressurized air intake system which introduces pressurized air into 
the retort and a exhaust system which evacuates gas from inside the 
retort, the internal pressure of the sealed retort can be set at a 
pressure at which the desired hot water drops are not instantly atomized 
by boiling with mutual operations of the pressurized air intake system 
which introduces pressurized air into the retort and the exhaust system 
which evacuates gas from inside the retort. As a result, it becomes easy 
to provide a retort sterilizer of high practical value which can blow 
desired hot water drops exactly and uniformly against the object material 
and equalize the temperature in the entire area of spraying to ensure a 
treatment of high efficiency.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
An example of the spray type retort sterilizer according to this invention 
is shown in FIG. 1 to FIG. 4. FIG. 1 is an approximate construction 
drawing of the spray type retort sterilizer according to this invention, 
FIG. 2 is a plan view showing the tray, the object material and the sprays 
and FIG. 3 is a partial perspective view showing the tank and the spray 
unit. 
In the spray type retort sterilizer indicated in FIG. 1, (1) is the tank 
constituting the retort of the retort sterilizer and is sealed during the 
treatment work. (2) are the plural numbers of stacked trays which are 
disposed inside the tank (1) so as to define stages. (3) is the object 
material arranged on the tray (2) consisting of gas foods, transfusion 
soft pack for medicine, etc. sealed in plastic packs containing a large 
quantity of gas to be submitted to high-pressure sterilization. (4) are 
the spray units disposed on both sides in each stage of the plural number 
of trays (2) inside the tank (1), intended to atomize and spray hot water 
or cooling water in the shape of sesame particles of a particle size of 
0.2.about.0.6 mm or so, in the horizontal direction in the shape of a fan 
for example, on the object material for treatment (3) in such a way that 
the spray may reach the entire surface of the tray (2) in each stage. (5) 
is the circulation route mounted on the tank (1) to blow the water 
accumulated at the bottom of the tank (1) as hot water or cooling water in 
the form of sesame particles from the spray unit again under pressure 
through the pump (6) and the heat exchanger (7). In the heating process, 
the circulating water flowing in the circulation route (5) is gradually 
heated with the steam (8) indirectly and this hot water is sprayed from 
the spray unit (4) in the tank (1) toward the object material for 
treatment (3) on the tray. When this heating process is over, cooling 
water (9) is supplied instead of the steam (8) as heat source of the heat 
exchanger (7) provided outside the tank (1) to gradually cool the hot 
water in the circulation route (5), which was used for spraying, 
indirectly with the heat exchanger (7), and this water is eventually 
sprayed on the object material for treatment (3) on the tray (2) from the 
spray unit (4) in the tank (1) at a temperature 3.degree..about.5.degree. 
C. higher than that of the cooling water. Moreover, the cooling water (9) 
is directly supplied to the spray unit (4) through the bypass valve (a) as 
required when the temperature of the circulating water dropped to some 
extent to a temperature area in which there is no fear of deformation of 
the formed container of the object material for treatment (3). [a 
temperature difference of 20.degree. C. or so for example, although this 
temperature varies depending on the product to be treated]. When suppling 
the cooling water (9) directly from the circulation route (5) to the spray 
unit (4) through the bypass valve (a), the water inside the tank (1) is 
evacuated through the drain valve (10) on the discharge side of the pump 
(6) to prevent the liquid level in the tank (1) from going up. (11) and 
(12) are a pressurized air intake system and an exhaust system described 
later characterizing this invention mounted on the tank (1). The 
pressurized air intake system (11) introduces pressurized air into the 
tank (1) while the exhaust system (12) exhausts gas from inside the tank 
(1). 
The spray unit (4) consists of a plural number of header pipes (14) having 
a large number of spray nozzles and disposed in upright position as shown 
in FIG. 2 and FIG. 3, the pitch of spray nozzles (13) being set equal to 
the pitch of piling of the trays (2). Of the plural number of header pipes 
(14), the header pipes (14) at both ends are formed a little shorter than 
others. In the same drawings, (15) are connecting pipes for introduction 
and connect the plural number of header pipes (14) at the center 
collectively and horizontally. (16) is an introducing pipe which is 
connected to the center of the connecting pipes for introduction (15) to 
lead to outside of the tank (1). (17) is a drive source such as torque 
actuator, etc., for example, provided outside the tank (1) and used to 
make the header pipes (14) rotationally oscillate in the vertical face 
with the introducing pipe (16) as central axis. (18) is the inlet of hot 
water or cooling water and communicates to the header pipes (14) through 
the introducing pipe (16) and the connecting pipes for introduction (15) 
by means of a communicating section (19) consisting of a rotary joint, 
etc., for example. 
The spray unit (4) is not necessarily limited to the said construction but 
may be constructed in such a way as provide a plural number of header 
pipes horizontally to make them rotationally oscillate or provide a plural 
number of header pipes vertically to make them move up and down in the 
vertical direction. 
Next, a concrete composition of a retort sterilizer according to this 
invention will be described based on FIG. 4. However, the details of the 
tank (1), the trays (2), the object material for treatment (3) and the 
spray unit (4) will be omitted to avoid duplication of explanation since 
they have already been described above. 
The heat exchanger (7) is a plate type heat exchanger having a heat 
receiving section (7a) and a heat discharging section (7b), the heat 
receiving section (7a) being connected to the bottom part of the tank (1) 
and the spray unit (4) so that the water at the bottom inside the tank (1) 
may be blown from the spray nozzles of the spray unit (4) in the form of 
water drops of desired particle size by the pump (6) through the heat 
receiving section (7a). The heat discharging section (7b) of the heat 
exchanger (7) is connected at one end in a switchable way with the steam 
source (20) and the cooling water inlet (21) through the stop valve for 
steam (22) of the heat exchanger and the cooling water inlet valve (23), 
and is connected at the other end with the cooling water outlet (25). In 
the drawing, (26) is a gate valve, (27) is an air vent valve for pump, 
(28) is a relief valve for heat exchanger, (29) is a cone strainer, (30) 
is a gate valve and (31) is a bypass valve for heat exchanger, all 
constituting the heat receiving system. (32) is a strainer for steam 
inlet, (33) is a stop valve for steam inlet, (34) is a steam inlet valve, 
(35) is a temperature regulating steam valve, (36) is a cooling water 
switching valve and (37) is a safety valve for heat exchanger, all 
constituting the heat discharging system. (38) is a drain & waste water 
outlet branching from the piping between the tank (1) and the pump (6), 
and is connected with the piping between the heat discharging section (7b) 
and the cooling water outlet (25) through a steam trap valve (39) and a 
steam trap (40). (41) is a waste water valve. (42) is a water source 
connected to the vicinity of the suction port of the pump (6) through a 
feed water check valve (43), a feed water stop valve (44) and a feed water 
valve (45) and supplying cooling water to the pump (6) through a cooling 
water stop valve for pump (46). 
In FIG. 4, (11), (12) are a pressurizd air intake system and an exhaust 
system constituting the main part of this invention and form an internal 
pressure regulating system of the tank (1) which regulates the internal 
pressure of the tank (1) by introducing pressurized air into the tank (1) 
with the pressurized air intake system (11) to prevent the water drops 
gushing from the spray nozzles (13) inside the tank (1) from instantly 
evaporating and discharges gas from inside the tank (1) with the exhaust 
system (12). (47) is a pressurized air source and (48) is an exhaust port 
and the pressurized air is supplied to the top part of the tank (1) 
through a stop valve for pressurized air (49) and a pressurizing valve 
(50). Branching from the piping between the tank (1) and the pressurizing 
valve (50) are a pipe line connected to the exhaust port (48) through an 
air vent valve (51) and a stop valve for exhaust air (52) and a pipe line 
opening in the atmosphere through an air intake valve (53). The said 
pressurized air is supplied not only to a solenoid valve through a stop 
valve for operating air (54) and a pressure reducing valve with filter 
(55) but also to the lid driving section through a pressure reducing valve 
with filter (56), a check valve for air (57) and a packing clamping valve 
(58). (59) is a packing opening valve, (60) is an air cylinder for locking 
the lid, (61) is a nozzle driving air cylinder, (62) is a vacuum breaker, 
(63) is a relief valve for tank and (64), (65) are drain cocks. The end 
parts (A), (B), (C), (D) of the pipe lines in the drawing are not 
illustrated but are connected with those of the same symbol respectively. 
In a retort sterilizer having a construction as described above, the header 
pipes (14) of the spray unit (4) having a large number of spray nozzles 
connected integrally through the communicating section (19), the 
introducing pipe (16) and the connecting pipes for introduction (15) 
rotationally oscillate in the vertical face with the operation of the 
drive source (17) and, while repeating this rotational oscillation, eject 
hot water or cooling water taken from the inlet (18) from the spray 
nozzles (13) via the connecting pipes for introduction (15) and the 
introducing pipe (16). The hot water or cooling water from the spray 
nozzles (13) is uniformly distributed around the tray (2) with the 
rotational oscillation of the header pipes (14) in a way to be uniformly 
sprayed on the object material for treatment (3) on the tray (2), thus 
ensuring uniform sterilization of the object material for treatment (3) 
regardless of the stacking condition of the trays (2). 
If, at this time, the internal pressure of the sealed tank (1) is equal to 
the atmospheric pressure, hot water drops of a particle size of 
100.degree. C. hot water ejected from the spray nozzles (13) instantly 
turn into steam by boiling and cannot be sprayed on the object material 
for treatment (3) in the desired state of hot water drops. For that 
reason, the internal pressure of the tank (1) is adjusted in 
correspondence to the sprayed hot water temperature with an internal 
pressure regulating system of the tank (1) composed of the pressurized air 
intake system (11) and the exhaust system (12). Namely, the internal 
pressure of the tank (1) can be set at a pressure at which the desired hot 
water drops are not instantly atomized by boiling with mutual operations 
of the pressurized air intake system (11) which introduces pressurized air 
into the tank (1) and the exhaust system (12) which evacuates gas from 
inside the tank (1). Therefore, even with hot water of a temperature of 
90.degree..about.130.degree. C., it is possible to blow hot water drops of 
a particle size of 0.2.about.0.6 mm uniformly against the object material 
and equalize the temperature in the entire area of spraying of ensure a 
treatment of high efficiency without any need of increasing the size of 
the hot water drops.