JPH09192016A - Vacuum deaeration system of steaming tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deaerate rapidly, economically, and effectively, by evacuating close to the saturating vacuum to the temperature of food to be sterilized and flush-evaporating the residual drain in a pipe to recover the pressure to a specified value and exhausting the residual air together with the generated steam. SOLUTION: A steaming tank 1 is provided with a temperature adjuster 3 and a temperature and pressure sensor 4. A vacuum switch is fitted to a vacuum exhaust line provided with a vacuum exhaust valve 6. In the vacuum deaeration process, the tank is evacuated from a vacuum exhaust valve 6 close to the saturating vacuum (about 30Torr) to the temperature (about 25 deg.C) of a treating material to be sterilized. In this time, the vacuum switch 17 is actuated to open an automatic cut-off valve 10 and instantaneously flush-evaporate the residual drain in the bypass pipe 11 in the prior batch operation and recover the pressure in the steaming tank 1 to about 100-360Torr. Accordingly, the residual air in the steaming tank 1 and the container 19 is accompanied by the generated steam and deaerated in the subsequent vacuum deaeration process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of processed foods such as cereals such as rice and beans, pasta, fish and other marine products, the food industry, and the sterilization apparatus for short-time cooking and sterilization of solids such as sterilized packaged rice. Related to a vacuum degassing system.

[0002]

2. Description of the Related Art A conventional vacuum degassing system for a cooking tank in a cooking and sterilizing apparatus for food and the like includes a steam type, a vacuum degassing type, and as a special case, a multi-time vacuum degassing type for sterilizing a mushroom culture medium. Used.

[0003]

Among the above-mentioned conventional examples, in the case of the steam type, the steam in the steaming tank can be degassed, but the air in the container in which foods or the like are loaded remains as it is and the heating is performed. There is a drawback that it becomes impossible to use when the container is filled with food in principle because of heat transfer failure at the time. In the vacuum degassing method, the air fraction during steaming is set to 0.21 as in the present invention.
In order to reduce the volume to 5 vol% or less, an ultimate vacuum of up to 4.5 torr is required, and obtaining such a degree of vacuum requires a significant increase in the vacuum generator. Economic ultimate vacuum degree of 30torr
When the steaming treatment is carried out, the air concentration in the porous space at the bottom of the container is further increased, and there is a disadvantage that heating unevenness occurs and sterilization is poor. That is, the average air concentration in the container is (30 / (760x2.754)) x1
00 = 1.433 vol%, whereas 1.
It is estimated that the air concentration is several times as high as 433 vol%.

In a special case of degassing a plurality of times of vacuum, after evacuation is stopped, evacuation is stopped once, steam is blown in, preheated to atmospheric pressure (100 ° C.), and vacuum degassing is performed again. The degassing effect is very high. The average air concentration in the container is (30/760) x (30 / (760x2.754)) x100 = 0.0566 vol%
It is estimated that the air concentration at the bottom of the container is several times this 0.0566 vol%, but it does not hinder heat transfer because it is orders of magnitude smaller than the single vacuum degassing method described above. . However, in this case, it is necessary to switch the operation between vacuum degassing, preheating, and re-vacuum degassing and perform the operation intermittently. When it takes time,
There is a disadvantage that the object to be processed is in a half-boiled state or ruptures during re-vacuum degassing. If preheating is performed in a short time within a few seconds using this method, the accuracy of the sensor cannot be improved and reproducibility is poor. In addition, energy is not saved because new steam is required for preheating.

As described above, in the conventional method, when a container is filled, there is no sufficient method for degassing. An object of the present invention is to solve the above-mentioned conventional difficulties and drawbacks, and to perform an economical and reproducible deaeration operation in a short time of several seconds on a porous object to be filled in a container. A vacuum degassing system for a steaming tank that eliminates sterilization defects, saves energy, can be realized without increasing the capacity of the vacuum generating pump, and can evenly increase the temperature inside the vessel during heating and cooking. It is something to offer.

[0006]

In order to achieve the above object, according to a first aspect of the present invention, a steaming tank is charged through a cassette containing water-immersed rice and other objects to be processed filled in a container.
In a cooking and sterilizing apparatus for cooking cereals and other foods to be heated and steamed, a tubular steaming machine fixedly installed in a horizontal direction, having one or two entrances, and having a temperature controller, a temperature sensor, and a pressure sensor. A tank, a pipe provided at the upper center of the steaming tank so as to be also used as a vacuum exhaust line having a vacuum exhaust valve and a vacuum switch, and a steam supply valve and a discharge valve, and lower ends of both ends of the tubular steaming tank. A condensed drain discharge nozzle is provided at the lower end of the steaming tank, and a plurality of condensed drain discharge nozzles are provided between the automatic shutoff valve and the check valve connected to the collected condensate drain outlet. A bypass pipe provided with a number of manual valves arranged in parallel in a vertical direction, and a drain discharge line composed of the bypass pipe and a steam trap. In saturation degree of vacuum close to the temperature of the object to be sterilized product (approximately 25 ℃) (approx 30tor
r) At this point, the vacuum switch is activated to open the automatic shut-off valve, and the drain remaining in the bypass pipe in the previous batch operation is flash-evaporated instantaneously. A vacuum degassing system for the steaming tank was provided, in which a pressure was instantaneously restored to about 100 to 360 torr and an evacuation step was performed to allow residual air in the steaming vessel and the container to accompany the generated steam.

In the second invention, the amount of drain remaining in the bypass pipe is changed by switching a plurality of manual valves to adjust the amount of drainage so as to obtain a deaeration rate corresponding to the degree of pressure recovery. A vacuum degassing system was used. In the third invention, a vacuum degassing system for a steaming tank in which a heat retaining section is provided in a bypass pipe having a residual drain.

(Action) In the first invention, the degree of vacuum can be adjusted by the vacuum switch of the vacuum exhaust line during the continuous operation of evacuation, supply and discharge of steam, and heating and steaming from the upper center of the steaming tank. In the batch operation, the drain remaining in the bypass pipe is used to flash-evaporate instantaneously to restore the pressure, thereby generating a forced discharge effect. Therefore, since a plurality of manual valves are arranged in parallel in the vertical direction so that a constant amount of drain can be prepared at a constant temperature in the bypass pipe, it is easy to adjust the amount of drain used, and the amount of heat retained can be effectively reduced. Available and reproducible degassing can be performed at once by operating the automatic shutoff valve.

Further, since it can be used within the range of a water ring pump or a water ring pump with a single-stage air ejector, a large pump performance is not required. Furthermore, the air that exists in the porous space like the grain in the food filled in the bottom of the container has the effect that the residual air causes a pump-up phenomenon and is forcibly discharged by the action of recompression and revacuum deaeration. . In particular, when a simple lid is used for the cassette containing the container, uneven air distribution is likely to occur in the steaming tank, but the uniformity is further improved by forcibly discharging the air. Further, since the positions of the vacuum evacuation and the steam supply are arranged so as to be uniformly changed around the center of the steaming tank, uniform processing can be performed.

In the second aspect of the present invention, the degree of decompression is changed by switching a plurality of manual valves in the bypass pipe to adjust the deaeration rate, so that switching can be performed according to the object to be processed. In the third aspect of the present invention, a heat retaining portion is provided in the bypass pipe having the remaining drain so that the temperature of the drain can be prevented from lowering.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, in a vacuum degassing step, a steaming treatment step by increasing the pressure and steam, and a cooking sterilization treatment in which the pressure is reduced, the vacuum degassing by a water ring pump or the like is performed before the pressure cooking treatment step. As a process, the temperature of the material to be sterilized (approximately 25 ° C.) is evacuated to a level close to a saturation degree of vacuum (approximately 30 torr). To flash evaporate the drain remaining in the bypass piping instantaneously,
The pressure in the steaming tank was restored to about 100 to 360 torr, and an evacuation step for entraining residual air in the steaming tank and the vessel with generated steam was provided, and a re-vacuum degassing step was performed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments shown in the drawings will be described below. FIG.
In the figure, reference numeral 1 denotes a steaming tank, which is tubular and has two entrances 2 and is fixedly installed in the horizontal direction. A temperature controller (TIC) 3 and a temperature sensor and a pressure sensor (P
I) 4 is attached. 5 is a piping, and a vacuum exhaust valve 6
The steam supply valve 7 and the discharge valve 8 are provided in the upper part of the center of the cooking tank 1 so as to serve as both. 9 is a collective condensate drain outlet,
Condensed drain discharge nozzles provided at the lower ends of both ends of the cylindrical steaming tank 1 were connected and provided at the lower center of the pipe. Reference numeral 10 denotes an automatic shut-off valve, which is connected to the collective drain port 9. 1
Reference numeral 1 denotes a bypass pipe, and a plurality of manual valves 12, 13, 14
−− was provided between the automatic shutoff valve 10 and the check valve 15 in parallel in the vertical direction. A steam trap 16 is a drain discharge line together with the bypass pipe 11. Reference numeral 17 denotes a vacuum switch (VS) provided on a vacuum exhaust line having the vacuum exhaust valve 6.

Reference numeral 18 denotes a cassette, which has a doorway 2 in the steaming tank 1.
Is loaded from. Reference numeral 19 denotes a container, and 20 denotes an object to be processed, such as rice, which is filled in the container 19. FIG. 2 is a temperature re-sipe showing a short-time cooking and sterilization treatment of foods and the like. In the case of a vacuum deaeration type, a vacuum deaeration step, a step of boosting and heating and steaming, and a step of depressurizing are performed. A feature of the present invention is that in the vacuum degassing step, the vacuum is exhausted from the evacuation valve 6 to a temperature close to the temperature of the material to be sterilized (about 25 ° C.) (approximately 30 torr) near the degree of vacuum. The switch 17 is operated to open the automatic shut-off valve 10, and the drain remaining in the bypass pipe 11 in the previous batch operation is flash-evaporated instantaneously to restore the pressure in the steaming tank to about 100 to 360 torr. Press. Therefore, the residual air in the steaming vessel and the vessel can be entrained in the generated steam by this evacuation step, and can be deaerated by the re-vacuum deaeration step.

FIG. 3 is an enlarged longitudinal sectional view of the steaming tank 1. The cassette 18 has holes 21 on the bottom surface and side surfaces, and is loaded into the steaming tank 1 via a transport rail 22. In the figure, A indicates the position of the bottom of the container 19, B indicates the position of the upper part of the container, C indicates the position of the upper part of the cassette, and D indicates the position of the lower part of the cassette. FIG. 4 is an assumption diagram of the partial pressure of air in the steaming tank, and the horizontal axis indicates the container 1.
The vertical axis indicates the partial pressure of air (mmHg).
A, B, C, and D indicate partial pressures at positions in FIG. A-
The space between B indicates the partial pressure of air in the container. 30 with normal vacuum pump
When vacuum is applied to torr, the air fraction is 1.433 vol% (2.75
4 atm) (see Fig. 6). On the other hand, in the vacuum degassing step, when the pressure was reduced by flash evaporation from 30 torr to one end of 200 torr and then the pressure was reduced again to 30 torr, 0.215 vol% (2.754 atm) was obtained (FIG. 5). reference). This is 4.5 torr when the pressure is not restored as in the conventional example.
It is a value that cannot be obtained unless the degree of vacuum is increased.

FIG. 5 shows the temperature in the steaming tank, the temperatures at the positions A, B and C in the vessel (left vertical axis) and the F value (sterilization value-right vertical axis) when the pressure is restored. Sterilization is sufficient if the F value is 10 or more. FIG. 6 shows the case where the pressure is not restored. The temperature at the position C in the container rises, but the F value cannot be measured at A at the bottom of the container. That is, the sterilization state is insufficient. (Example 1) Amount of rice soaked in water: 110 g / container Number of containers: 8 x 2 = 16 / batch Temperature of rice soaked in water: 25 ° C Ultimate vacuum: 30 torr Vacuum of recompressing pressure: 200 torr (1 sec )-Automatic shut-off valve-Open (Saturation temperature: 66.5 Latent heat of evaporation: 559 kcal / kg Specific volume: 5.8 m ³ / kg) Total vacuum deaeration time: 2.5 min Residual air ratio: (30/200) x ( 30 / (760x2.754)) x100 = 0.215 vol% Heating time: 1 min Steaming temperature: 130 ° C (1.754 KG, 2.754 KA) Steaming time: 4.5 min Pressure down time: 0.5 min (steam discharge)-At atmospheric pressure stop - automatic shutoff valves - the dimensions of the closed cooking vessel: 150A x L2200 cooking tank capacity: 43.8 liters vacuum pump: 1.5 kw (pumping speed 0.6 m ³ / min) drain temperature: 100 ° C. drain weight: 380 g flash evaporation: 380x1x (100-66.5) / 559 = 22.8 g batch 22.8x5.8 = 132 liters / batch According to the recalculation result of the above-mentioned recompression, in order to obtain recompression 200 torr, flash steam of 3 times the capacity of the steaming tank is required. Need quantity

[0016]

According to the first aspect of the present invention, in the vacuum deaeration process, the air can be forcibly discharged by a simple operation of merely opening the automatic shut-off valve, so that effective deaeration can be realized by a short operation of several seconds. it can. Drain from the previous batch process is 100 ℃
In addition, the reproducibility is extremely high because it is limited only to the amount of the bypass pipe. Sterilization value F
It is sufficient that the value also exceeds 10. In addition, since the drain from the previous batch process is used and no new steam is required to recover the pressure, energy can be saved.

According to the second aspect of the present invention, the amount of drain remaining in the bypass pipe can be easily changed by switching a plurality of manual valves to obtain a deaeration rate corresponding to the degree of pressure recovery. In the third invention, a heat retaining portion is provided in the bypass pipe having the remaining drain to prevent the temperature from dropping to 100 ° C. or less.

[Brief description of the drawings]

FIG. 1 is a system diagram of a vacuum degassing system.

FIG. 2 is a process diagram of heat cooking sterilization.

FIG. 3 is an enlarged sectional view of a steaming tank.

FIG. 4 is an explanatory view of the partial pressure of air inside the steaming tank.

FIG. 5 is a graph showing the temperature of the steaming tank and the degree of sterilization when the pressure is restored.

FIG. 6 is a graph showing the sterilization degree and the temperature of the steaming tank when the pressure is not restored.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steaming tank 2 Doorway 3 Temperature controller 4 Pressure sensor 5 Piping 6 Vacuum exhaust valve 7 Steam supply valve 8 Steam discharge valve 9 Collecting condensate drain outlet 10 Automatic shut-off valve 11 Bypass piping 12, 13, 14 Plural manual Valve 15 Check valve 16 Steam trap 17 Vacuum switch 18 Cassette 19 Container 20 Workpiece

Claims (3)

[Claims] 1. A cooking and disinfecting apparatus for cereals and other foods which is charged into a steaming tank via a cassette containing water-immersed rice and other objects to be filled and heat-steamed, and is fixedly installed in a horizontal direction. Vacuum evacuation line and steam supply having one or two inlets / outlets, a cylindrical steaming tank having a temperature controller, a temperature sensor and a pressure sensor, a vacuum evacuation valve and a vacuum switch. A pipe provided at the upper center of the steaming tank so as to be used as both a valve and a discharge valve, and a nozzle for discharging condensed drain at both lower ends of the tubular steaming tank. A bypass pipe in which a plurality of manual valves are provided in parallel in a vertical direction between an automatic shutoff valve and a check valve connected to the collective condensation drain outlet provided in the bypass pipe; and Plumbing and steam A drain discharge line comprising a trap, and in a vacuum deaeration step using a water ring pump or the like before the pressure steaming step, a degree of vacuum (approximately 30 torr) close to the temperature of the material to be sterilized (about 25 ° C.) ), And at this point the vacuum switch is activated to open the automatic shut-off valve, and the drain remaining in the bypass pipe in the previous batch operation is flash-evaporated instantaneously, and the pressure in the steaming tank is reduced. Vacuum degassing of the steaming tank characterized by providing an evacuation step of instantaneously recovering the pressure to about 100 to 360 torr, entraining residual air in the steaming vessel and the vessel with generated steam, and performing a re-vacuum degassing step. system. 2. The amount of drain remaining in the bypass pipe is
2. The vacuum degassing system for a steaming tank according to claim 1, wherein the vacuum degassing system of the steaming tank can be adjusted by changing a plurality of manual valves to obtain a degassing rate according to the degree of pressure recovery. 3. The vacuum degassing system for a steaming tank according to claim 1, wherein a heat retaining section is provided in a bypass pipe having the residual drain.