JP7049582B2 - Sterilizer - Google Patents

Description

The present invention relates to a sterilizer used for heat sterilization of retort foods and the like.

Conventionally, a sterilizer disclosed in Patent Document 1 below is known. In this sterilizer, the object to be treated (2) is housed in the treatment tank (1) and water is stored, and the stored water is circulated to and from the heat exchanger (3). Then, it is switched between heating the circulating water with steam in the heat exchanger and cooling with the cooling water from the cooling tower (8), and heat sterilization of the object to be processed and subsequent cooling are achieved.

Japanese Patent No. 4229420

In the sterilizer, after a temperature raising step of raising the inside of the treatment tank to the sterilization temperature, a sterilization step of keeping the inside of the treatment tank at the sterilization temperature is performed. The temperature control in these steps is performed by controlling the steam supply to the heat exchanger. In the prior art, a valve is provided in the steam supply path to the heat exchanger, and by controlling this valve, the steam supply into the processing tank is controlled.

For temperature control in the processing tank, it is conceivable to use, for example, a proportional control valve as the valve. However, in the case of heating control only with a valve whose opening can be adjusted, if leakage through the valve (steam leakage due to poor closure) occurs, steam supply to the inside of the processing tank will continue even if the target temperature is exceeded. The desired sterilization (sterilization at the target temperature) cannot be performed, and the food may be overheated or quality deterioration such as a change in taste may occur, and the food may need to be disposed of.

Therefore, an object to be solved by the present invention is to provide a sterilizer that can easily adjust the temperature with a simple configuration and control and can cope with a malfunction in the unlikely event. That is, even if a leak occurs through the valve, the desired sterilization can be carried out, the overheating of the food can be prevented, and the quality deterioration such as the change in taste can be prevented, and the waste of the food can be suppressed. The subject is to provide the device.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 has a treatment tank in which an object to be treated is stored and water is stored, and a treatment tank in which water is stored in the treatment tank. Steam supply that heats the circulating water in the circulation path by supplying steam to the circulation means that circulates through the circulation path and the heat exchanger provided in the circulation path, or by blowing steam into the circulating water in the circulation path. The steam supply means includes means and control means for controlling each of the means, and the steam supply means includes a steam supply shutoff valve that switches on / off the presence or absence of steam supply to the heat exchanger or the steam supply path to the circulation path. A steam supply valve whose opening degree can be adjusted is provided in series, and the control means sequentially executes a temperature raising step of raising the inside of the treatment tank to the sterilization temperature and a sterilization step of keeping the inside of the treatment tank at the sterilization temperature. However, at least in the sterilization step, the control means adjusts the opening degree of the steam supply valve with the steam supply shutoff valve open, but when the temperature in the processing tank becomes equal to or higher than the steam supply shutoff temperature, The sterilizer is characterized in that the steam supply shutoff valve is closed, and then the steam supply shutoff valve is opened when the temperature in the processing tank becomes equal to or lower than the steam supply restart temperature.

According to the first aspect of the present invention, in a sterilizer that circulates the stored water in the treatment tank by a circulation means and heats the circulating water with steam, the steaming means for heating the circulating water is a circulation path. Alternatively, the steam supply path to the heat exchanger provided therein is provided in series with a steam supply shutoff valve for switching on / off the presence or absence of steam supply and a steam supply valve whose opening can be adjusted. Then, at least in the sterilization step, the temperature in the processing tank can be appropriately adjusted by adjusting the opening degree of the steam supply valve with the steam supply shutoff valve open. However, when the temperature inside the treatment tank exceeds the steam supply shutoff temperature, the steam supply shutoff valve is closed, while when the temperature inside the treatment tank falls below the steam supply restart temperature, the steam supply shutoff valve is opened for processing. Adjust the temperature inside the tank. That is, in the unlikely event that a malfunction occurs in the steam supply valve and a leak occurs through the valve, the food supply cutoff valve can be closed to prevent overheating of the food when the temperature exceeds the supply steam cutoff temperature. After that, the temperature inside the treatment tank drops due to heat dissipation, but when the temperature drops below the steam supply restart temperature, the food can be sterilized by heating by opening the steam supply shutoff valve. In this way, even if a malfunction occurs in the steam supply valve whose opening can be adjusted, the opening and closing of the steam supply shutoff valve can be controlled on and off between the supply steam cutoff temperature and the steam supply restart temperature. It is possible to carry out sterilization of food, prevent overheating of food, prevent quality deterioration such as change in taste, and suppress food waste.

According to the second aspect of the present invention, the control means of the steam feeder so as to maintain the temperature in the processing tank within the sterilization temperature range between the upper limit temperature and the lower limit temperature in the sterilization step. The claim is characterized in that the opening degree is adjusted , the steam supply cutoff temperature is set at a temperature exceeding the upper limit temperature, and the steam supply restart temperature is set above the lower limit temperature and below the upper limit temperature. Item 1 is the sterilizing apparatus.

According to the second aspect of the present invention, since the steam supply cutoff temperature is set at a temperature exceeding the upper limit temperature of the sterilization temperature range, the opening degree adjustment of the steam supply valve can be preferentially executed. Then, in the unlikely event that a malfunction occurs in the steam supply valve and a leakage occurs through the valve, the supply / steam isolation valve is closed when the temperature exceeds the supply / steam isolation temperature. After that, when the temperature drops below the steam supply restart temperature, the steam supply shutoff valve is opened, but the steam supply restart temperature is set above the lower limit temperature of the sterilization temperature range and below the upper limit temperature, so the desired sterilization should be continued. Can be done.

Further, in the third aspect of the present invention, when the sterilization step is completed by on / off control of the steam supply shutoff valve between the steam supply cutoff temperature and the steam supply restart temperature, a notification means to that effect is used. The sterilizer according to claim 1 or 2, wherein the sterilizer is notified.

According to the third aspect of the present invention, when sterilization is performed by opening and closing the steam supply shutoff valve instead of sterilization by adjusting the opening degree of the steam supply valve, the notification means notifies the user. Therefore, it is possible to confirm the sterilization status of the object to be treated and to determine whether or not the product can be shipped. It can also encourage maintenance of the sterilizer.

According to the sterilizer of the present invention, the temperature can be easily adjusted with a simple configuration and control, and it is possible to deal with a malfunction in the unlikely event. In other words, even if a leak occurs through the valve, the desired sterilization can be carried out, overheating of the food can be prevented, and quality deterioration such as change in taste can be prevented to suppress the disposal of the food. Can be done.

It is a schematic diagram which shows the sterilizer of one Example of this invention, and shows a part in a cross section. It is a schematic diagram which shows the operation example of the sterilizer of FIG. 1, the horizontal axis shows time t, and the vertical axis shows the temperature T in a processing tank.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing a sterilizer 1 according to an embodiment of the present invention, and is partially shown in a cross section. The sterilization device 1 of this embodiment is a device that heats and sterilizes the object to be processed 2, and is configured to be able to cool the object to be processed 2 after sterilization. The object 2 to be processed is not particularly limited, but is typically a food material sealed in a container such as a retort food or a canned food.

The sterilizer 1 of the present embodiment includes a treatment tank 3 in which the object to be treated 2 is housed, a water supply means 4 into the treatment tank 3, a drainage means 5 to the outside of the treatment tank 3, and a treatment tank 3. Compressed air supply means 6, exhaust means 7 to the outside of the treatment tank 3, vacuum release means 8 in the treatment tank 3, and circulation means 10 for circulating water between the treatment tank 3 and the heat exchanger 9. , The steaming means 11 that supplies steam to the heat exchanger 9 to heat the circulating water by the circulating means 10, and the drain discharging means 12 that discharges the condensed water (drain) of the steam by the steaming means 11 to the outside. A cooling means 13 for supplying cooling water to the heat exchanger 9 for cooling the circulating water by the circulation means 10 and a control means (not shown) for controlling each of these means 4 to 8, 10 to 13 are provided.

The treatment tank 3 is a hollow container for accommodating the object to be treated 2. The shape of the treatment tank 3 is not particularly limited, but in the present embodiment, the treatment tank 3 includes a horizontally arranged cylindrical material, in which one opening is closed and the other opening is opened and closed by a door. It is possible. By opening the door, the object to be processed 2 can be taken in and out of the processing tank 3, and by closing the door, the opening of the processing tank 3 can be closed airtightly. The object to be processed 2 is held above the bottom surface in the processing tank 3 by being placed on a trolley or the like.

The treatment tank 3 is provided with a temperature sensor 14 for detecting the temperature in the treatment tank 3 and a water level sensor (not shown) for detecting the water level in the treatment tank 3. However, the temperature sensor 14 may be provided not in the processing tank 3 but in the circulation path 15 (particularly on the downstream side of the heat exchanger 9) described later. Further, although not shown, the treatment tank 3 is provided with a pressure sensor for detecting the pressure in the treatment tank 3 and a product temperature sensor for detecting the temperature of the object to be processed contained in the treatment tank 3, if desired. ..

The water supply means 4 supplies water into the treatment tank 3 via the water supply channel 16. The water supply channel 16 is connected to the bottom of the treatment tank 3 and is provided with a water supply pump 17 and a water supply valve 18 toward the treatment tank 3. When the water supply valve 18 is opened with the water supply pump 17 operated, water from the water supply source can be supplied into the treatment tank 3 and the water can be stored in the treatment tank 3. In this embodiment, water is stored in the treatment tank 3 up to a set water level at which the object to be treated contained in the treatment tank 3 is not immersed.

The drainage means 5 discharges water from the treatment tank 3 via the drainage channel 19. The drainage channel 19 is connected to the bottom of the treatment tank 3 and is provided with a drainage valve 20. By opening the drain valve 20, the water in the treatment tank 3 can be discharged to the outside.

The compressed air supply means 6 supplies compressed air into the processing tank 3 via the compressed air supply path 21. The compressed air supply path 21 is connected to the upper part of the processing tank 3, and a compressed air shutoff valve 22 and a compressed air valve 23 are provided toward the processing tank 3. By opening the compressed air valve 23 with the compressed air shutoff valve 22 open, the compressed air from the compressed air source is supplied into the processing tank 3 to pressurize the inside of the processing tank 3 to a pressure exceeding the atmospheric pressure. be able to.

The exhaust means 7 discharges gas from the inside of the processing tank 3 under a pressure exceeding atmospheric pressure through the exhaust passage 24. The exhaust passage 24 is connected to the upper part of the processing tank 3 and is provided with an exhaust valve 25. When the exhaust valve 25 is opened while the pressure inside the treatment tank 3 exceeds the atmospheric pressure, the gas in the treatment tank 3 is discharged to the outside through the exhaust passage 24, and the pressure in the treatment tank 3 can be lowered. can.

The vacuum release means 8 introduces outside air into the treatment tank 3 under a pressure lower than the atmospheric pressure through the air supply passage 26. The air supply passage 26 is connected to the upper part of the treatment tank 3 and is provided with a vacuum release valve 27. When the vacuum release valve 27 is opened while the pressure inside the treatment tank 3 is lower than the atmospheric pressure, the outside air is introduced into the treatment tank 3 through the air supply passage 26, and the pressure inside the treatment tank 3 is increased to the atmospheric pressure. Can be returned.

Water is circulated to and from the treatment tank 3 in the heat exchanger 9, and heat is exchanged between the circulating water and the steam or cooling water without mixing. That is, in the heat exchanger 9, the water from the treatment tank 3 is passed by the circulation means 10, and the steam by the steam supply means 11 is passed to heat the circulating water, or the circulating water is cooled. The cooling water by the cooling means 13 is passed therethrough.

The circulation means 10 circulates water between the treatment tank 3 and the heat exchanger 9. The circulation means 10 includes a circulation path 15 and a circulation pump 28. One end of the circulation path 15 is connected to the bottom of the treatment tank 3, and the circulation path 15 from the bottom of the treatment tank 3 passes through the circulation pump 28 and the heat exchanger 9 in order, and the other end of the circulation path 3 is the treatment tank 3. It is connected to the nozzle 29 inside. The nozzle 29 is provided on a side portion and / or an upper portion in the processing tank 3 and injects water from the circulation pump 28 toward the object to be processed 2.

The steaming means 11 supplies steam to the heat exchanger 9 to heat the circulating water by the circulating means 10. The steaming means 11 includes a steaming passage 30 that supplies steam from the boiler to the heat exchanger 9, and the steaming passage 30 is provided with a steaming shutoff valve 31 and a steaming valve 32 in series. .. In the illustrated example, the steam supply passage 30 is provided with the steam supply isolation valve 31 and the steam supply valve 32 in this order toward the treatment tank 3, but in some cases, the steam supply valve 32 is conversely provided. And the steam supply shutoff valve 31 may be provided in this order. The steam supply shutoff valve 31 is a valve (for example, an air-driven valve) that switches the presence or absence of steaming on and off, and the steam supply valve 32 is a valve whose opening degree can be adjusted (for example, a motor valve).

The drain discharge means 12 discharges the condensed water of the steam supplied to the heat exchanger 9 by the steam supply means 11 to the outside. The drain discharge means 12 includes a drain discharge passage 33 downward from the heat exchanger 9, and the drain discharge valve 34, the steam trap 35, and the check valve 36 are sequentially provided in the drain discharge passage 33. By opening the drain discharge valve 34 at the time of supplying steam to the heat exchanger 9, the condensed water of steam can be discharged to the outside.

The cooling means 13 supplies cooling water to the heat exchanger 9 to cool the circulating water by the circulation means 10. The cooling means 13 includes a cooling tower 37, and the water cooled by the cooling tower 37 is supplied to the heat exchanger 9 through the cooling water feed path 39 by the water supply pump 38, and the water after passing through the heat exchanger 9. Is returned to the cooling tower 37 via the cooling water return path 40. In the case of the illustrated example, the cooling water feed path 39 and the steam supply path 30 are common pipelines on the heat exchanger 9 side. Further, the cooling water return path 40 and the drain discharge path 33 are common pipelines on the heat exchanger 9 side.

The cooling water feed path 39 is provided with a cooling water feed valve 41, while the cooling water return path 40 is provided with a cooling water return valve 42. The confluence of the cooling water feed passage 39 and the steam supply passage 30 is arranged on the downstream side (heat exchanger 9 side) of the cooling water feed valve 41 and the steam supply valve 32. Further, the branch portion between the cooling water return path 40 and the drain discharge path 33 is arranged on the upstream side (heat exchanger 9 side) of the cooling water return valve 42 and the drain discharge valve 34.

When the cooling water feed valve 41 and the cooling water return valve 42 are opened and the water supply pump 38 is operated with the steam supply valve 32 and the drain discharge valve 34 closed, cooling is performed between the cooling tower 37 and the heat exchanger 9. Water can be circulated. On the other hand, if the steam supply valve 32 is opened with the cooling water feed valve 41 and the cooling water return valve 42 closed, steam can be supplied to the heat exchanger 9. At that time, by opening the drain discharge valve 34, the drain can be discharged via the steam trap 35.

The control means is a controller (not shown) that controls each of the means 4 to 8, 10 to 13 based on the elapsed time and the like in addition to the detection signal of each sensor. Specifically, a water supply pump 17, a water supply valve 18, a drain valve 20, a compressed air shutoff valve 22, a compressed air valve 23, an exhaust valve 25, a vacuum release valve 27, a circulation pump 28, a steam supply shutoff valve 31, and a steam supply valve. 32, a drain discharge valve 34, a cooling tower 37, a water supply pump 38, a cooling water feed valve 41, a cooling water return valve 42, a temperature sensor 14, a water level sensor, and the like are connected to a controller. Then, as described below, the controller performs heat sterilization of the object to be treated 2 in the treatment tank 3 and subsequent cooling according to a predetermined procedure (program).

FIG. 2 is a schematic view showing an operation example of the sterilizer 1 of the present embodiment, in which the horizontal axis shows the time t and the vertical axis shows the temperature T in the processing tank. The sterilizer 1 typically includes a water supply step S1 followed by a temperature raising step S2 and a sterilization step S3 at least once to sterilize the object 2 to be treated, and then performs a cooling step S4 and a drainage step S5. Run. FIG. 2 shows an example in which the water supply step S1, the first temperature raising step S2a, the first sterilization step S3a, the second temperature rising step S2b, the second sterilization step S3b, the cooling step S4, and the drainage step S5 are sequentially executed. There is.

Although the temperature rise target temperature is different between the first temperature rise step S2a and the second temperature rise step S2b, the operation contents are the same. Therefore, each of the temperature raising steps S2a and S2b may be simply referred to as the temperature rising step S2, unless the two are particularly distinguished below. Similarly, the first sterilization step S3a and the second sterilization step S3b have different holding target temperatures, but the operation contents are the same. Therefore, each of the sterilization steps S3a and S3b may be simply referred to as the sterilization step S3, unless the two are particularly distinguished below.

Hereinafter, each step will be described. First, prior to the operation of the sterilizer 1, the object 2 to be processed is housed in the processing tank 3, and the door of the processing tank 3 is airtightly closed. In that state, the drain valve 20, the exhaust valve 25, the vacuum release valve 27, and the drain discharge valve 34 are opened among the above-mentioned valves, but the other valves 18, 22, 23, 31, 32, 41, 42 is closed and pumps 17, 28 and 38 are stopped.

≪Water supply process S1≫
In the water supply step S1, water is supplied into the treatment tank 3 by the water supply means 4 to a set water level at which the object 2 to be treated in the treatment tank 3 is not immersed, and the water is stored in the treatment tank 3. Specifically, the drain valve 20 and the vacuum release valve 27 are closed with the exhaust valve 25 open. Then, the water supply valve 18 may be opened with the water supply pump 17 operated. When water is stored in the treatment tank 3 up to the set water level, the water supply valve 18 is closed and the water supply pump 17 is stopped to end the water supply step S1. In the latter half of the water supply step S1, the circulation pump 28 may be intermittently operated and switched to continuous operation with the transition to the temperature rising step S2.

<< Temperature rise step S2 >>
In the temperature rising step S2, water is circulated between the treatment tank 3 and the heat exchanger 9 by the circulation means 10, and the circulating water is heated by the steam supply means 11 in the heat exchanger 9 to be inside the treatment tank 3. The temperature of the above is raised to the sterilization temperature T1 (T2). Specifically, by operating the circulation pump 28, the water from the inner bottom of the treatment tank 3 is returned from the nozzle 29 to the inside of the treatment tank 3 via the heat exchanger 9, and the heat is exchanged with the treatment tank 3. Circulate with the vessel 9. Further, during this circulation, the cooling water feed valve 41 and the cooling water return valve 42 are closed, while the steam supply shutoff valve 31 and the steam supply valve 32 are opened to supply steam to the heat exchanger 9. At this time, it is preferable to proportionally control (or PID control) the opening degree of the steam supply valve 32 based on the detected temperature of the temperature sensor 14 so that the temperature in the processing tank 3 rises at a desired speed. By opening the drain discharge valve 34, the condensed water of steam is discharged through the steam trap 35.

In the temperature raising step S2, the circulating water and steam can be heat-exchanged in the heat exchanger 9 to heat the circulating water. In this way, in the temperature raising step S2, the temperature inside the treatment tank 3 is gradually raised, but at this time, the pressure inside the treatment tank 3 exceeds the atmospheric pressure (higher than the saturated steam pressure corresponding to the temperature inside the treatment tank 3). ). As a result, circulation can be performed without causing cavitation of the circulation pump 28 even at a water temperature exceeding 100 ° C., and the container (retort pouch or the like) can be prevented from bursting due to expansion of the object to be processed. Specifically, by controlling the compressed air valve 23 and the exhaust valve 25, pressurization is performed according to the temperature in the processing tank 3.

After that, the circulation of water by the circulation means 10 is continued until the end of the cooling step S4. Further, the pressurization in the treatment tank 3 by the compressed air supply means 6 is made higher than the saturated steam pressure corresponding to the temperature in the treatment tank 3 even after the inside of the treatment tank 3 has risen to the sterilization temperature, and the drainage in the drainage step S5 is performed. It will continue until the end. During that time, the compressed air shutoff valve 22 is maintained in an open state, and the opening and closing of the compressed air valve 23 and the exhaust valve 25 is controlled.

<< Sterilization process S3 >>
In the sterilization step S3, the temperature inside the treatment tank 3 is maintained at the sterilization temperature T1 (T2), and the object to be treated 2 is heated and sterilized. Specifically, the opening degree of the steam supply valve 32 is adjusted so as to maintain the detection temperature of the temperature sensor 14 at the sterilization temperature while circulating the stored water in the treatment tank 3 by the circulation means 10. During this time, by opening the drain discharge valve 34, the condensed water of steam is discharged via the steam trap 35. When the sterilization time elapses in the treatment tank 3 at a sterilization temperature or higher, the steam supply valve 32 and the steam supply shutoff valve 31 are closed to stop the steam supply to the heat exchanger 9, and the sterilization step S3 is completed.

The sterilization temperature may be changed during the heat sterilization of the object 2 to be treated. In the illustrated example, the first sterilization step S2a for raising the temperature in the treatment tank 3 up to the first sterilization temperature T1, the first sterilization step S3a for holding the first sterilization time at the first sterilization temperature T1, and the first sterilization temperature T1. The second sterilization step S2b for raising the temperature in the treatment tank 3 to a high second sterilization temperature T2 and the second sterilization step S3b for holding the second sterilization time at the second sterilization temperature T2 are sequentially executed.

In the illustrated example, the sterilization temperature was changed in two stages of the first sterilization temperature T1 and the second sterilization temperature T2, but the sterilization temperature was changed in three stages of the first sterilization temperature T1, the second sterilization temperature T2 and the third sterilization temperature T3. May be changed (increased in stages). Alternatively, the sterilization temperature may be changed in four or more steps, or conversely, the sterilization temperature may not be changed (that is, only the first sterilization temperature T1 may be used).

Further, in the illustrated example, an example in which the sterilization temperature is raised is shown, but the sterilization temperature may be lowered in the middle. When lowering the sterilization temperature, the circulating water by the circulating means 10 is cooled by the cooling water by the cooling means 13 or the water supply means 4 is used in the same manner as in the cooling step S4 described later with the heating by the steaming means 11 stopped. After controlling the drainage means 5 and performing a temperature lowering step of gradually replacing the stored water in the treatment tank 3, the sterilization step S3 may be carried out.

In the sterilization step S3, as described above, with the steam supply shutoff valve 31 open, the opening degree of the steam supply valve 32 is adjusted to maintain the temperature inside the processing tank 3 at the sterilization temperature. However, when the temperature in the processing tank 3 becomes equal to or higher than the supply / steam cutoff temperature, the supply / steam isolation valve 31 is closed, while when the temperature in the treatment tank 3 becomes equal to or lower than the supply / steam restart temperature, the supply / steam cutoff valve 31 is opened. Is good. It is preferable that the steam supply cutoff temperature is set by the sterilization temperature + the first set value α, and the steam supply restart temperature = the sterilization temperature + the second set value β (however, 0 <β <α). If the sterilization temperature is changed in the middle, the steam supply cutoff temperature and the steam supply restart temperature are also changed accordingly.

More specifically, in the present embodiment, in the sterilization step S3, the opening degree of the steam supply valve 32 is maintained so that the temperature in the treatment tank 3 is maintained in the sterilization temperature range between the upper limit temperature and the lower limit temperature. To adjust. For example, in proportional control (or PID control), a proportional band (for example, ± 1 ° C.) is provided for the set temperature, and the opening degree of the steam supply valve 32 is set within the range between the upper limit temperature and the lower limit temperature of the proportional band. To adjust. In this case, the steam supply valve 32 is fully closed at the upper limit temperature or higher, and the steam supply valve 32 is fully open at the lower limit temperature or lower. Then, the steam supply cutoff temperature is set at a temperature exceeding the upper limit temperature (feeding cutoff temperature = upper limit temperature + first set value), and the feed steaming restart temperature is set above the lower limit temperature and below the upper limit temperature. Is preferable.

In the case of such a configuration, basically, the temperature in the treatment tank 3 is adjusted by the proportional control (or PID control) of the steam supply valve 32 with the steam supply shutoff valve 31 open, but the treatment is performed. When the temperature in the tank 3 becomes equal to or higher than the steam supply shutoff temperature, the steam supply shutoff valve 31 is closed, while when the temperature in the treatment tank 3 becomes equal to or lower than the feed steam supply restart temperature, the steam supply shutoff valve 31 is opened. The temperature inside the processing tank 3 is adjusted. That is, in the unlikely event that a malfunction occurs in the steam supply valve 32 and a leakage (close failure) occurs through the valve, when the temperature exceeds the steam supply cutoff temperature, the food supply cutoff valve 31 is closed to overheat the food. Can be prevented. After that, the temperature inside the processing tank 3 drops due to heat dissipation, but when the temperature becomes lower than the steam supply restart temperature, the food can be continuously sterilized by heating by opening the steam supply shutoff valve 31. In this way, even if a malfunction occurs in the steam supply valve 32 whose opening can be adjusted, the opening / closing of the steam supply shutoff valve 31 can be controlled on and off between the feed steam supply cutoff temperature and the steam supply restart temperature. It is possible to carry out the desired sterilization, prevent overheating of food, prevent quality deterioration such as change in taste, and suppress food waste.

Moreover, since the steam supply cutoff temperature is set at a temperature exceeding the upper limit temperature of the sterilization temperature range, it is possible to give priority to adjusting the opening degree of the steam supply valve 32. Then, in the unlikely event that a malfunction occurs in the steam supply valve 32 and a leakage occurs through the valve, the steam supply isolation valve 31 is closed when the temperature exceeds the supply steam cutoff temperature. After that, when the temperature becomes lower than the supply steam restart temperature, the steam supply shutoff valve 31 is opened, but since the feed steam supply restart temperature is set to be equal to or higher than the lower limit temperature of the sterilization temperature range and lower than the upper limit temperature, the desired sterilization is continued. be able to.

It should be noted that such backup control for leakage of the steam supply valve 32 through the valve can be performed not only in the sterilization step S3 but also in the temperature rising step S2. That is, as a premise, in the temperature raising step, the temperature in the processing tank 3 is increased to a predetermined value according to the elapsed time, but the temperature is supplied so as to be within the range of the upper limit temperature and the lower limit temperature of the target temperature at each time point. The opening degree of the steam valve 32 is adjusted. Then, by gradually increasing the upper limit temperature and the lower limit temperature, the temperature inside the treatment tank 3 is raised to the sterilization temperature range. On the premise of this, in the temperature rise step S2 as well as the sterilization step S3, the steam supply cutoff temperature is set as a temperature higher than the upper limit temperature by a predetermined temperature at each time point in the temperature rise step S2, while at the lower limit temperature or higher. Moreover, the steam supply restart temperature is set below the upper limit temperature. As a result, in the temperature rise step S2 as well as in the sterilization step S3, when a leakage through the valve occurs due to a defective closing of the steam supply valve 32, the steam supply shutoff valve 31 is closed at a temperature equal to or higher than the steam supply cutoff temperature, while the supply is supplied. The temperature rise step S2 can be carried out by repeatedly opening the steam supply shutoff valve 31 at a temperature equal to or lower than the steaming restart temperature and controlling the on / off control of the steam supply shutoff valve 31.

<< Cooling process S4 >>
In the cooling step S4, water is circulated between the treatment tank 3 and the heat exchanger 9 by the circulation means 10, and the circulating water is cooled by the cooling means 13 in the heat exchanger 9 to cover the inside of the treatment tank 3. The processed material 2 is cooled. Specifically, the circulation pump 28 returns the water from the inner bottom of the treatment tank 3 from the nozzle 29 to the inside of the treatment tank 3 via the heat exchanger 9, whereby the treatment tank 3 and the heat exchanger 9 are combined. Circulate water between them. Further, during this circulation, the cooling tower 37 and the water pump 38 are operated with the cooling water feed valve 41 and the cooling water return valve 42 open while the steam supply valve 32 and the drain discharge valve 34 are closed to heat exchanger. Cooling water may be circulated in 9.

When the cooling time elapses from the start of the cooling step S4, the temperature in the processing tank 3 drops below the cooling temperature, or a predetermined time elapses after the temperature drops below the cooling temperature, the cooling water to the heat exchanger 9 by the cooling means 13 The supply is stopped and the cooling step S4 is terminated. At this time, the circulation by the circulation means 10 is also stopped, but the pressurization in the treatment tank 3 by the compressed air supply means 6 should be continued until the drainage is completed in the drainage step S5.

≪Drainage process S5≫
In the drainage step S5, drainage is performed from the inside of the treatment tank 3 by the drainage means 5. Specifically, by opening the drain valve 20, water is discharged to the outside. If the inside of the treatment tank 3 is pressurized by the compressed air supply means 6 and drained by the drainage means 5, the drainage from the inside of the treatment tank 3 can be performed quickly. Further, by opening the drain discharge valve 34, the cooling water accumulated on the primary side of the heat exchanger 9 is discharged to the outside.

After that, while closing the compressed air shutoff valve 22 and the compressed air valve 23, the exhaust valve 25 is opened to release the pressurization in the processing tank 3, and then the vacuum release valve 27 is further opened to open the inside of the processing tank 3. Make sure to set the atmospheric pressure. As a result, the door of the processing tank 3 can be opened and the object to be processed 2 can be taken out from the inside of the processing tank 3.

When the sterilization step S3 is completed by the on / off control of the steam supply shutoff valve 31 between the supply steam cutoff temperature and the steam supply restart temperature, it is preferable to notify the fact by the notification means. For example, if a buzzer, a lamp, a display (touch panel) or the like is provided as a notification means and sterilization is performed by opening and closing the steam supply shutoff valve 31 instead of sterilization by adjusting the opening degree of the steam supply valve 32, the sterilization is performed by voice or display. The user may be notified to that effect. As a result, it is possible to confirm the sterilization status of the object to be treated 2 and determine whether or not to ship it. It is also possible to promote maintenance of the sterilizer 1 (particularly the steam supply valve 32).

The sterilizer 1 of the present invention is not limited to the configuration (including control) of the above embodiment, and can be appropriately changed. For example, in the above embodiment, the heat exchanger 9 is installed in the circulation path 15, and in the heat exchanger 9, it is switched between heating the circulating water with steam and cooling the circulating water with cooling water. The installation of the exchanger 9 may be omitted. In that case, in the temperature raising step S2 and the sterilization step S3, steam can be directly blown into the circulating water of the circulation path 15 to heat the circulating water. Also in this case, the steam supply passage 30 to the circulation passage 15 is provided with the steam supply isolation valve 31 and the steam supply valve 32, and can be controlled in the same manner as in the above embodiment. By blowing steam into the circulating water, the steam condenses and the amount of retained water increases, but by controlling the drainage means 5, the water level in the treatment tank 3 is maintained within the set range. Further, in the cooling step S4, the water supply means 4 and the drainage means 5 are controlled, and the water in the treatment tank 3 is gradually replaced, so that the object to be treated 2 can be cooled.

Further, it can be applied to the so-called hot water storage type sterilizer 1. In that case, the object to be treated 2 is submerged in hot water to sterilize it in the treatment tank 3, but the stored water in the treatment tank 3 is circulated with the heat exchanger 9 as in the above embodiment. At the same time, the circulating water is heated by steam in the sterilization step S3 and cooled by the cooling water in the cooling step S4.

1 Sterilizer 2 Processed object 3 Treatment tank 4 Water supply means 5 Drainage means 6 Compressed air supply means 7 Exhaust means 8 Vacuum release means 9 Heat exchanger 10 Circulation means 11 Steam supply means 12 Drain discharge means 13 Cooling means 14 Temperature sensor 15 Circulation path 16 Water supply channel 17 Water supply pump 18 Water supply valve 19 Drainage channel 20 Drain valve 21 Compressed air supply path 22 Compressed air shutoff valve 23 Compressed air valve 24 Exhaust channel 25 Exhaust valve 26 Air supply channel 27 Vacuum release valve 28 Circulation pump 29 Nozzle 30 Steam supply channel 31 Steam supply shutoff valve 32 Steam supply valve 33 Drain discharge channel 34 Drain discharge valve 35 Steam trap 36 Check valve 37 Cooling tower 38 Water supply pump 39 Cooling water supply path 40 Cooling water return path 41 Cooling water feed valve 42 Cooling Water return valve

Claims (3)

A treatment tank in which the object to be treated is stored and water is stored,
A circulation means for circulating the stored water in this treatment tank via a circulation path,
A steam supply means for supplying steam to a heat exchanger provided in the circulation path or blowing steam into the circulation water of the circulation path to heat the circulation water of the circulation path.
A control means for controlling each of the above means is provided.
The steaming means is provided with a steaming isolation valve for switching on / off the presence or absence of steaming and a steaming valve whose opening can be adjusted in series in the heat exchanger or the steaming path to the circulation path.
The control means sequentially executes a temperature raising step of raising the inside of the treatment tank to the sterilization temperature and a sterilization step of keeping the inside of the treatment tank at the sterilization temperature.
At least in the sterilization step, the control means adjusts the opening degree of the steam supply valve with the steam supply shutoff valve open, but when the temperature in the processing tank becomes equal to or higher than the steam supply cutoff temperature, the supply is supplied. A sterilizer characterized in that the steam supply shutoff valve is closed, and then the steam supply shutoff valve is opened when the temperature in the processing tank becomes equal to or lower than the steam supply restart temperature. The control means adjusts the opening degree of the steam supply valve so that the temperature in the processing tank is maintained in the sterilization temperature range between the upper limit temperature and the lower limit temperature in the sterilization step.
The steam supply cutoff temperature is set at a temperature exceeding the upper limit temperature, and is set.
The sterilizer according to claim 1, wherein the steam supply restart temperature is set to be equal to or higher than the lower limit temperature and lower than the upper limit temperature. 1. The sterilizer according to claim 2.

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