Heat sterilization device, sterilization object, and heat sterilization method

Abstract

This heat sterilization device 100 comprises a sterilization tank 1 that has an accommodation space 1d accommodating, in the interior thereof, a sterilization object Rp on which heat sterilization is performed using a high-temperature fluid Hth, and that is supplied with a cooling water Cw for cooling the high-temperature fluid Hth which heat-sterilizes the sterilization object Rp and the sterilization object Rp which has been heat-sterilized using the high-temperature fluid Hth. The heat sterilization device 100 also comprises a control unit that, prior to the cooling of the heat sterilization object Rp using the cooling water Cw, performs mid-temperature water heat recovery control in which heat in the sterilization tank 1 after heat sterilization is recovered using a mid-temperature water Htm that is generated separately from the high-temperature fluid Hth and has a temperature that is higher than the temperature of the cooling water Cw and lower than the temperature of the high-temperature fluid Hth.

Description

Heat sterilization device, object to be sterilized, and heat sterilization method

[0001] The present invention relates to a heat sterilization device, an object to be sterilized, and a heat sterilization method.

[0002] A heat sterilization apparatus for heat sterilizing an object to be sterilized is known in the art. For example, Japanese Patent Application Laid-Open No. 2000-69948 discloses such a heat sterilization apparatus.

[0003] The above-mentioned Japanese Patent Application Laid-Open No. 2000-69948 discloses a cooking sterilization device (heat sterilization device) for heat sterilizing an object to be sterilized (an object to be sterilized).

[0004] The cooking sterilization apparatus disclosed in JP 2000-69948 A includes a sterilization tank, a hot water tank, a cold water tank, a water supply tank, a spray nozzle, a heat exchanger, and a control device (control unit). The sterilization tank contains objects to be sterilized. The hot water tank is a tank for storing hot water to be sprayed from the spray nozzle. To heat-sterilize the objects contained in the sterilization tank, the spray nozzle heats the hot water supplied from the hot water tank to a heat-sterilization temperature and sprays it into the sterilization tank as a jet of water (high-temperature fluid). In this cooking sterilization apparatus, after heat sterilization with the high-temperature jet of water, the hot water supplied from the hot water tank is cooled by heat exchange with water supplied from the water supply tank in the heat exchanger so that the temperature of the hot water is reduced to a predetermined temperature. Then, in the cooking sterilization apparatus, the hot water that has been cooled to the predetermined temperature is collected in the hot water tank. Thereafter, the cooking sterilization apparatus is configured to spray cooling water supplied from a cold water tank into the sterilization tank as a jet of water in order to cool the heated objects to be sterilized and the sterilization tank after heat sterilization.

[0005] Japanese Patent Application Laid-Open No. 2000-69948

[0006] However, in the cooking sterilization apparatus of JP 2000-69948 A, the temperature of the high-temperature hot water that has been heated to the sterilization temperature is lowered by heat exchange with low-temperature cold water in the heat exchanger before being recovered in the hot water tank. Therefore, the cooking sterilization apparatus of JP 2000-69948 A has the problem that it takes a long time to heat the hot water (high-temperature fluid) to the sterilization temperature during the next sterilization after heat recovery.

[0007] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a heat sterilization device, an object to be sterilized, and a heat sterilization method that can prevent the time required to heat the high-temperature fluid up to the heat sterilization temperature from becoming long during the next heat sterilization after heat recovery.

[0008] A heat sterilization apparatus according to a first aspect of the present invention has an accommodation space for accommodating objects to be heat sterilized with a high-temperature fluid, and comprises a sterilization tank to which the high-temperature fluid for heat sterilizing the objects and cooling water for cooling the objects heat-sterilized with the high-temperature fluid are supplied, and a control unit for performing medium-temperature water heat recovery control to recover heat from the sterilization tank after heat sterilization using medium-temperature water that is generated separately from the high-temperature fluid and has a temperature higher than that of the cooling water but lower than that of the high-temperature fluid, before the objects to be sterilized are cooled with the cooling water.

[0009] In the heat sterilization apparatus according to the first aspect of the present invention, as described above, a control unit is provided that performs medium-temperature water heat recovery control, which recovers heat from the sterilization tank after heat sterilization using medium-temperature water generated separately from the high-temperature fluid, the medium-temperature water being higher than the cooling water but lower than the high-temperature fluid, before cooling the objects to be sterilized with cooling water. This prevents the temperature of the high-temperature fluid from decreasing by recovering heat from the sterilization tank after heat sterilization using medium-temperature water generated separately from the high-temperature fluid. This prevents a long time from increasing in temperature for the high-temperature fluid to be heated to the sterilization temperature during the next heat sterilization after heat recovery. Furthermore, the sterilization tank after heat sterilization can be cooled with medium-temperature water at a temperature higher than the cooling water before cooling the objects to be sterilized with cooling water, thereby preventing a sudden temperature change (sudden temperature drop) in the sterilization tank after heat sterilization. As a result, the degree of expansion and contraction of the sterilization tank can be reduced, which, unlike when large expansion and contraction are repeated, prevents metal fatigue due to thermal stress and reduces a decrease in the durability (lifespan) of the sterilization tank.

[0010] In the heat sterilization apparatus according to the first aspect, the control unit is preferably configured to perform the medium-temperature water heat recovery control in a state in which the high-temperature fluid after heat sterilization has been discharged from the sterilization tank. With this configuration, heat recovery using the high-temperature fluid is performed simply by discharging the high-temperature fluid, eliminating the need for a dedicated heat exchanger and water supply tank for heat recovery using the high-temperature fluid, thereby preventing the apparatus from becoming larger in size due to heat recovery using the high-temperature fluid.

[0011] The heat sterilization apparatus according to the first aspect preferably further includes a medium-temperature water tank for storing medium-temperature water, and the control unit is configured to perform medium-temperature water heat recovery control for recovering heat from the sterilization tank after heat sterilization using medium-temperature water supplied from the medium-temperature water tank before cooling the objects to be sterilized with cooling water, and to store the medium-temperature water used for the medium-temperature water heat recovery control in the medium-temperature water tank. With this configuration, storing medium-temperature water in the medium-temperature water tank makes it possible to easily supply the medium-temperature water to the sterilization tank after heat sterilization during heat recovery, and storing the medium-temperature water used for heat recovery in the medium-temperature water tank without discharging it makes it possible to easily reuse the recovered heat.

[0012] In this case, preferably, the control unit is configured to perform preheating control to preheat the sterilization tank using the medium-temperature water heated during the medium-temperature water heat recovery control and stored in the medium-temperature water tank before heating the objects to be sterilized with the high-temperature fluid. With this configuration, preheating the sterilization tank using the medium-temperature water heated during heat recovery can increase the initial temperature of the sterilization tank at the start of thermal sterilization. Therefore, compared to when preheating is not performed, the amount of heat imparted to the high-temperature fluid during heating to the temperature required for thermal sterilization can be reduced. In other words, by using medium-temperature water, the heat recovered can be effectively used for preheating. As a result, when preheating is performed, the thermal energy required in the thermal sterilization apparatus can be reduced, thereby reducing the amount of (high-temperature) steam used to heat the high-temperature water.

[0013] In a heat sterilization apparatus in which the control unit is configured to perform preheating control to preheat the sterilization tank using medium-temperature water, the control unit preferably further includes a first connection path connecting the sterilization tank and the medium-temperature water tank, and the control unit is configured to perform control to recover and store the medium-temperature water in the sterilization tank after heat recovery in the medium-temperature water tank via the first connection path, and control to supply medium-temperature water to the sterilization tank via the first connection path during preheating. With this configuration, the first connection path can be used to easily store the medium-temperature water in the medium-temperature water tank after heat recovery, and to supply medium-temperature water from the medium-temperature water tank to the sterilization tank during preheating.

[0014] In the heat sterilization apparatus, the control unit is preferably configured to control the discharge of medium-temperature water supplied from the medium-temperature water tank toward the objects to be sterilized during both the preheating of the sterilization tank and the heat recovery of the sterilization tank. With this configuration, during preheating of the sterilization tank, the temperature of the medium-temperature water is lowered by directing the discharged medium-temperature water toward the objects to be sterilized, and the lowered-temperature medium-temperature water is applied to the sterilization tank, thereby suppressing a sudden temperature change in the low-temperature sterilization tank during preheating. Furthermore, during heat recovery of the sterilization tank, the temperature of the medium-temperature water is raised by directing the discharged medium-temperature water toward the objects to be sterilized, and the increased-temperature medium-temperature water is applied to the sterilization tank, thereby suppressing a sudden temperature change in the high-temperature sterilization tank during heat recovery. These features suppress a decrease in the durability of the sterilization tank due to increased thermal stress caused by a sudden temperature change during both the preheating of the sterilization tank and the heat recovery of the sterilization tank.

[0015] The heat sterilization apparatus according to the first aspect preferably further comprises a high-temperature water tank for recovering and storing high-temperature water, which is a high-temperature fluid after heat sterilization stored in the sterilization tank, and a second connection path connecting the sterilization tank and the high-temperature water tank, and the control unit is configured to recover the high-temperature water discharged from the sterilization tank after heat sterilization of the objects to be sterilized into the high-temperature water tank via the second connection path, and then perform medium-temperature water heat recovery control for the sterilization tank. With this configuration, by recovering the high-temperature water from the sterilization tank via the dedicated second connection path connecting the sterilization tank and the high-temperature water tank, heat loss from the high-temperature water can be prevented after heat sterilization control, and a decrease in the temperature of the high-temperature water recovered in the high-temperature water tank can be suppressed.

[0016] The heat sterilization apparatus having the medium-temperature water tank preferably further includes a heat transfer fluid supply unit that supplies a heat transfer fluid heated by medium-temperature water, and a heat exchanger that performs heat exchange between the medium-temperature water stored in the medium-temperature water tank and the heat transfer fluid supplied from the heat transfer fluid supply unit, and the control unit is configured to control the supply of the heat transfer fluid, whose temperature has been increased by heat exchange with the medium-temperature water in the heat exchanger, to the sterilization tank during preheating of the sterilization tank, and to control the supply of the heat transfer fluid, whose temperature has been lowered by heat exchange with the medium-temperature water in the heat exchanger, during heat recovery of the sterilization tank. With this configuration, the preheating temperature can be lowered compared to when medium-temperature water is directly supplied to the sterilization tank, thereby further suppressing sudden temperature changes in the sterilization tank.

[0017] The heat sterilization apparatus according to the first aspect preferably further comprises a circulation path including a circulation pump that discharges each of the cooling water, high-temperature fluid, and medium-temperature water discharged from the sterilization tank and circulates them back into the sterilization tank, and the control unit is configured to perform medium-temperature water heat recovery control by circulating the medium-temperature water to the sterilization tank through the circulation path using the circulation pump. With this configuration, the circulation path used for each of the heat sterilization control and the cooling control can be used in common for the heat recovery control, thereby preventing the structure from becoming complicated and large-sized due to an increase in the number of paths in the heat sterilization apparatus.

[0018] According to a second aspect of the present invention, objects to be sterilized are heat-sterilized by a heat sterilization device having an accommodation space for accommodating objects to be heat-sterilized with a high-temperature fluid, a sterilization tank to which the high-temperature fluid for heat-sterilizing the objects and cooling water for cooling the objects heat-sterilized with the high-temperature fluid are supplied, and a control unit for performing medium-temperature water heat recovery control to recover heat from the sterilization tank after heat sterilization, using medium-temperature water that is generated separately from the high-temperature fluid and has a temperature higher than that of the cooling water but lower than that of the high-temperature fluid, before the objects to be sterilized are cooled with the cooling water.

[0019] In the second aspect of the present invention, as described above, before the object to be sterilized is cooled with cooling water, it is heat-sterilized by a heat sterilizer equipped with a control unit that performs heat recovery control to recover heat from the sterilization tank after heat sterilization using medium-temperature water that is higher than the cooling water but lower than the temperature of the high-temperature fluid. In this way, by recovering heat from the sterilization tank after heat sterilization using medium-temperature water generated separately from the high-temperature fluid, it is possible to prevent the temperature of the high-temperature fluid from decreasing, thereby making it possible to prevent an increase in the time required to heat the high-temperature fluid to the sterilization temperature during the next heat sterilization after heat recovery and to prevent a decrease in the durability of the sterilization tank due to an increase in thermal stress caused by a sudden temperature change.

[0020] A heat sterilization method according to a third aspect of the present invention comprises the steps of: supplying a high-temperature fluid to a sterilization tank where heat sterilization is performed with the high-temperature fluid, and heat sterilizing objects in the sterilization tank; recovering heat from the sterilization tank after heat sterilization using medium-temperature water that is higher than the cooling water but lower than the high-temperature fluid and that is generated separately from the high-temperature fluid, before cooling the objects to be sterilized with cooling water; and cooling the objects that have been heat-sterilized with cooling water after heat recovery from the sterilization tank.

[0021] In the heat sterilization method according to the third aspect of the present invention, as described above, a step of recovering heat from the sterilization tank after heat sterilization using medium-temperature water that is higher than the cooling water but lower than the temperature of the high-temperature fluid is provided before cooling the objects to be sterilized with cooling water. This allows the temperature of the high-temperature fluid to be prevented from decreasing by recovering heat from the sterilization tank after heat sterilization using medium-temperature water that is produced separately from the high-temperature fluid, thereby providing a heat sterilization method that can prevent an increase in the time required to raise the temperature of the high-temperature fluid to the sterilization temperature during the next heat sterilization after heat recovery and that can prevent a decrease in the durability of the sterilization tank due to an increase in thermal stress caused by a sudden temperature change.

[0022] The heat sterilization method according to the third aspect preferably further comprises a step of preheating the sterilization tank using medium-temperature water heated during heat recovery from the sterilization tank before supplying the high-temperature fluid for heat sterilization of the objects to be sterilized to the sterilization tank. By preheating the sterilization tank using the medium-temperature water heated during heat recovery, the initial temperature of the sterilization tank at the start of heat sterilization can be increased. This reduces the amount of heat imparted to the high-temperature fluid when raising the temperature of the high-temperature fluid to the temperature required for heat sterilization, compared to when preheating is not performed. In other words, by using medium-temperature water, the recovered heat can be effectively used for preheating. As a result, the increase in thermal energy required in the heat sterilization device when preheating is performed can be suppressed.

[0023] According to the present invention, as described above, it is possible to prevent the time required for raising the temperature of the high-temperature fluid to the heat sterilization temperature from becoming long during the next heat sterilization after heat recovery.

[0024] 7 is a schematic diagram showing a heat sterilization apparatus of the present embodiment; FIG. 8 is a block diagram showing an overview of using heat recovered by heat recovery in the preheating step of the next heat sterilization control in the heat sterilization control of the heat sterilization apparatus of the present embodiment; FIG. 9 is a graph showing the relationship between time during heat sterilization control by the heat sterilization apparatus of the present embodiment and temperature change in the sterilization tank; FIG. 10 is a graph showing the relationship between time during heat sterilization control by a heat sterilization apparatus of a comparative example and temperature change in the sterilization tank; FIG. 11 is a schematic diagram showing preparation of high-temperature water performed before the carry-in step of the heat sterilization apparatus of the present embodiment; FIG. 12 is a schematic diagram showing preparation of medium-temperature water performed before the carry-in step of the heat sterilization apparatus of the present embodiment; FIG. 13 is a schematic diagram showing the carry-in step in the heat sterilization control of the heat sterilization apparatus of the present embodiment; FIG. 14 is a schematic diagram showing a medium-temperature water injection step in the preheating step in the heat sterilization control of the heat sterilization apparatus of the present embodiment, which is a diagram showing the medium-temperature water injection step subsequent to the carry-in step shown in FIG. 7; FIG. 15 is a schematic diagram showing a medium-temperature water circulating step in the preheating step in the heat sterilization control of the heat sterilization apparatus of the present embodiment, which is a diagram showing the medium-temperature water circulating step subsequent to the medium-temperature water injection step shown in FIG. 10 is a schematic diagram showing the medium-temperature water recovery step of the preheating step in the heat sterilization control of the heat sterilizer of this embodiment, and is a diagram showing the medium-temperature water recovery step following the medium-temperature water circulation step shown in Figure 9.

[0033] Figure 11 is a schematic diagram showing the high-temperature water injection step of the object heating step in the heat sterilization control of the heat sterilizer of this embodiment, and is a diagram showing the high-temperature water injection step following the medium-temperature water recovery step shown in Figure 10.

[0034] Figure 12 is a schematic diagram showing the high-temperature water recovery step of the object heating step in the heat sterilization control of the heat sterilizer of this embodiment, and is a diagram showing the high-temperature water injection step following the high-temperature water recovery step shown in Figure 13.

[0035] Figure 13 is a schematic diagram showing the high-temperature water injection step of the object heating step and the heat sterilization step in the heat sterilization control of the heat sterilizer of this embodiment, and is a diagram showing the temperature rise step following the high-temperature water injection step shown in Figure 11.

[0036] Figure 14 is a schematic diagram showing the high-temperature hydrothermal recovery step by recovering high-temperature water into a high-temperature water tank in the high-temperature hydrothermal recovery step in the heat sterilization control of the heat sterilizer of this embodiment, and is a diagram showing the high-temperature hydrothermal recovery step following the temperature rise step shown in Figure 12.

[0037] Figure 15 is a schematic diagram showing the medium-temperature water injection step of the medium-temperature hydrothermal heat recovery step in the heat sterilization control of the heat sterilizer of this embodiment, and is a diagram showing the medium-temperature water injection step following the high-temperature hydrothermal recovery step shown in Figure 13. 15 is a schematic diagram showing the medium-temperature water circulation step of the medium-temperature water heat recovery step in the heat sterilization control of the heat sterilization device of this embodiment, and is a diagram showing the medium-temperature water circulation step subsequent to the medium-temperature water injection step shown in FIG.17 is a schematic diagram showing the medium-temperature water recovery step of the medium-temperature water heat recovery step in the heat sterilization control of the heat sterilization device of the present embodiment, and is a diagram showing the medium-temperature water recovery step following the medium-temperature water circulation step shown in FIG. 15. FIG. 18 is a schematic diagram showing the cooling water injection step of the object cooling step in the heat sterilization control of the heat sterilization device of the present embodiment, and is a diagram showing the cooling water injection step following the medium-temperature water recovery step shown in FIG. 16. FIG. 19 is a schematic diagram showing the cooling step of the object cooling step in the heat sterilization control of the heat sterilization device of the present embodiment, and is a diagram showing the cooling step following the cooling water injection step shown in FIG. 17. FIG. 19 is a schematic diagram showing the cooling water recovery step of the object cooling step in the heat sterilization control of the heat sterilization device of the present embodiment, and is a diagram showing the cooling water recovery step following the cooling step shown in FIG. 18. FIG. 20 is a schematic diagram showing the carry-out step in the heat sterilization control of the heat sterilization device of the present embodiment. FIG. 21 is a diagram comparing a graph of heat sterilization control by a heat sterilization device of a comparative example with a graph of heat sterilization control by the heat sterilization device of the present embodiment. FIG. 22 is a flowchart showing a heat sterilization method by the heat sterilization device of the present embodiment. Fig. 1 is a schematic diagram showing a state of an object heating process of a hot water storage type heat sterilizer of a first modified example of this embodiment, Fig. 2 is a schematic diagram showing a state of an object heating process of a steam type heat sterilizer of a second modified example of this embodiment, Fig. 3 is a schematic diagram showing a heat sterilizer of a third modified example of this embodiment.

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0026] The configuration of a heat sterilization apparatus 100 according to this embodiment will be described with reference to FIGS. 1 to 22.

[0027] (Heat Sterilization Apparatus) As shown in Figure 1, the heat sterilization apparatus 100 according to this embodiment is a spray-type apparatus that heats a retort pouch Rp containing food with high-temperature water Hth to heat and sterilize the food and the retort pouch Rp. The retort pouch Rp containing food is an example of an "object to be sterilized" in the claims. The high-temperature water Hth is an example of a "high-temperature fluid" in the claims.

[0028] As shown in FIG. 1 , the spray-type heat sterilization device 100 according to this embodiment includes a sterilization tank 1, a spray nozzle 2, a high-temperature water tank 3, a medium-temperature water tank 4, a circulation path 5, a supply path 6, a discharge path 7, a discharge path 8, a supply path 9, a discharge path 10, a heat exchanger 11, and a control unit 12.

[0029] (Sterilization Tank) The sterilization tank 1 is a sealed container that heat-sterilizes the retort pouches Rp with high-temperature water Hth and cools the heat-sterilized retort pouches Rp with cooling water Cw. Medium-temperature water Htm is supplied to the sterilization tank 1 to preheat the retort pouches Rp and recover heat. The medium-temperature water Htm is water that is generated separately from the high-temperature water Hth and has a temperature higher than that of the cooling water Cw but lower than that of the high-temperature water Hth. Preheating and heat recovery using the medium-temperature water Htm will be described in detail later. The sterilization tank 1 includes a loading / unloading door 1a, a temperature sensor 1b, a water level sensor 1c, a storage space 1d, and a storage space 1e.

[0030] The loading / unloading door 1a is a door that is opened and closed by a user when loading and unloading trays Tr, each stacked in multiple layers and carrying a plurality of retort pouches Rp, into and from the sterilization tank 1. The temperature sensor 1b is a sensor for measuring the temperature inside the sterilization tank 1. The water level sensor 1c is a sensor for measuring the water levels of the high-temperature water Hth, the medium-temperature water Htm, and the cooling water Cw stored in the storage space 1e. The storage space 1d is a space that stores the retort pouches Rp to be heat-sterilized with the high-temperature water Hth. The storage space 1e is a space for storing the high-temperature water Hth, the medium-temperature water Htm, and the cooling water Cw when preheating, heat-sterilization, heat recovery, and cooling are performed. The storage space 1e is a space below the lowest tray Tr of the stacked trays Tr in the storage space 1d.

[0031] (Spray Nozzle) The spray nozzle 2 in the spray-type heat sterilization apparatus 100 according to this embodiment is configured to spray each of high-temperature water Hth, medium-temperature water Htm, and cooling water Cw into the sterilization tank 1. The spray nozzle 2 includes a plurality of injection ports 2a. Each of the plurality of injection ports 2a is arranged in accordance with the position of a plurality of stacked trays Tr. As a result, the high-temperature water Hth, medium-temperature water Htm, and cooling water Cw sprayed from the spray nozzle 2 are each sprayed toward the retort pouches Rp placed on the trays Tr. A plurality of spray nozzles 2 configured in this manner are arranged in the sterilization tank 1.

[0032] (High-Temperature Water Tank) As shown in Figure 1, the high-temperature water tank 3 is a tank that collects and stores high-temperature water Hth, which is a high-temperature fluid stored in the sterilization tank 1 after heat sterilization. The high-temperature water tank 3 has a hot water storage space that can store high-temperature water Hth with a volume equal to the combined volume of the storage space 1e, the circulation path 5, and the supply path 6. The high-temperature water tank 3 includes a temperature sensor 3a and a water level sensor 3b. The temperature sensor 3a is a sensor for measuring the temperature inside the high-temperature water tank 3. The water level sensor 3b is a sensor for measuring the water level of the high-temperature water Hth stored in the hot water storage space.

[0033] (Medium-Temperature Water Tank) Here, the medium-temperature water tank 4 in this embodiment is a tank that collects and stores the medium-temperature water Htm stored in the sterilization tank 1 after preheating and heat recovery. The medium-temperature water tank 4 has a medium-temperature water storage space that can store the medium-temperature water Htm with a volume equal to the combined volume of the storage space 1e, the circulation path 5, and the supply path 6. As shown in FIG. 1 , the medium-temperature water tank 4 includes a temperature sensor 4a and a water level sensor 4b. The temperature sensor 4a is a sensor for measuring the temperature inside the medium-temperature water tank 4. The water level sensor 4b is a sensor for measuring the water level of the medium-temperature water Htm stored in the medium-temperature water storage space.

[0034] 1, the circulation path 5 is a path that returns the cooling water Cw, high-temperature water Hth, and medium-temperature water Htm discharged from the sterilization tank 1 to the sterilization tank 1 via a heat exchanger 11. The circulation path 5 includes a discharge pipe 5a, a discharge pipe 5b, an upstream pipe 5c, a downstream pipe 5d, a temperature sensor 5e, a circulation pump 5f, and a flow path switching valve 5g.

[0035] The discharge pipes 5a and 5b are pipes for discharging the cooling water Cw, high-temperature water Hth, and medium-temperature water Htm stored in the storage space 1e. The upstream pipe 5c connects the heat exchanger 11 to the discharge pipes 5a and 5b. The downstream pipe 5d connects the heat exchanger 11 to the sterilization tank 1. The circulation pump 5f discharges the cooling water Cw, high-temperature water Hth, and medium-temperature water Htm discharged from the sterilization tank 1 and circulates them back to the sterilization tank 1. The circulation pump 5f also returns the high-temperature water Hth discharged from the sterilization tank 1 to the high-temperature water tank 3. The circulation pump 5f also returns the medium-temperature water Htm discharged from the sterilization tank 1 to the medium-temperature water tank 4. The flow path switching valve 5g is a valve for switching the flow paths through which the cooling water Cw, high-temperature water Hth, and medium-temperature water Htm flow.

[0036] (Supply Path) The supply path 6 is a pipe that branches off from the circulation path 5 and supplies high-temperature water Hth to the high-temperature water tank 3. The supply path 6 is also a pipe that branches off from the circulation path 5 and supplies medium-temperature water Htm to the medium-temperature water tank 4. The supply path 6 includes a common pipe 6a, branch pipes 6b, 6c, a flow path switching valve 6d, and a flow path switching valve 6e. The common pipe 6a is connected to the circulation path 5 and is a common pipe for the high-temperature water tank 3 and the medium-temperature water tank 4. The branch pipe 6b branches off from the common pipe 6a and is connected to the high-temperature water tank 3. The branch pipe 6c branches off from the common pipe 6a and is connected to the medium-temperature water tank 4.

[0037] (Discharge Path) The discharge path 7 is a pipe connecting the high-temperature water tank 3 and the discharge path 8 so that the high-temperature water Hth in the high-temperature water tank 3 flows into the circulation path 5. The discharge path 7 includes a connecting pipe 7a and a flow path switching valve 7b. The discharge path 8 is a pipe connecting the medium-temperature water tank 4 and the circulation path 5 so that the medium-temperature water Htm in the medium-temperature water tank 4 flows into the circulation path 5. The discharge path 8 includes a connecting pipe 8a and a flow path switching valve 8b.

[0038] Here, the circulation path 5, the common pipe 6a and branch pipe 6c of the supply path 6, and the connecting pipe 8a of the discharge path 8 are an example of a "first connecting path" in the claims, which connects the sterilization tank 1 and the medium-temperature water tank 4 to each other. The circulation path 5, the common pipe 6a and branch pipe 6b of the supply path 6, and the connecting pipe 8a of the discharge path 8 are an example of a "second connecting path" in the claims, which connects the sterilization tank 1 and the high-temperature water tank 3 to each other. Cooling water Cw, supplied from a cooling water source 200 provided in the factory where the heat sterilization apparatus 100 is installed, flows into the circulation path 5. The cooling water Cw is supplied to a portion of the upstream pipe 5c upstream of the circulation pump 5f.

[0039] (Supply Path) The supply path 9 is a path that connects the heat exchanger 11 to a steam inlet 301 of a boiler facility and a cooling water inlet 401 of a cooling water source, both of which are provided in a factory where the heat sterilization apparatus 100 is installed. The supply path 9 includes a common pipe 9a, a connection pipe 9b, a flow path switching valve 9c, and a flow path switching valve 9d.

[0040] (Discharge path) Discharge path 10 is a path that connects heat exchanger 11 to steam drain 302 and cooling water outlet 402, which are provided in a factory where heat sterilization apparatus 100 is installed. Discharge path 10 includes common pipe 10a, connecting pipe 10b, flow path switching valve 10c, flow path switching valve 10d, and steam trap 10e.

[0041] 1 , the heat exchanger 11 is a member that heats each of the cooling water Cw and the high-temperature water Hth by exchanging heat between each of the cooling water Cw and the high-temperature water Hth flowing through the circulation path 5 and steam flowing in from the steam inlet 301. The heat exchanger 11 is a member that cools the cooling water Cw by exchanging heat between the cooling water Cw flowing through the circulation path 5 and the cooling water flowing in from the cooling water inlet 401.

[0042] (Control Unit) The control unit 12 is configured to control the heat sterilization apparatus 100. The control unit 12 includes a CPU (Central Processing Unit), a storage unit such as an SSD (Solid State Drive) or HDD (Hard Disk Drive), and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit stores a heat sterilization program that controls the loading and unloading of the retort pouch Rp in the heat sterilization apparatus 100, and controls the heat sterilization, cooling, preheating, and heat recovery of the retort pouch Rp.

[0043] The control unit 12 is electrically connected to the temperature sensor 1b, the water level sensor 1c, the temperature sensor 3a, the water level sensor 3b, the temperature sensor 4a, the water level sensor 4b, the temperature sensor 5e, the circulation pump 5f, the flow path switching valve 5g, the flow path switching valve 6d, the flow path switching valve 6e, the flow path switching valve 7b, the flow path switching valve 8b, the flow path switching valve 9c, the flow path switching valve 9d, the flow path switching valve 10c, and the flow path switching valve 10d. The control unit 12 is also electrically connected to not only the above-mentioned sensors but also a flow rate measurement sensor, a pressure sensor, and the like.

[0044] The control unit 12 controls the loading and unloading of the retort pouches Rp, and controls the thermal sterilization, cooling, preheating, and heat recovery of the retort pouches Rp, based on necessary measurement information from various sensors.

[0045] (Outline of Operation Control of Heat Sterilization Apparatus of the Present Embodiment) First, an outline (concept) of operation control of the heat sterilization apparatus 100 of the present embodiment (hereinafter referred to as "heat sterilization control") will be described with reference to FIG.

[0046] As shown in Fig. 2, the heat sterilization control of this embodiment includes a preheating step, an object heating step, a high-temperature water heat recovery step, a medium-temperature water heat recovery step, and an object cooling step as a series of processes. The heat sterilization control of this embodiment reduces the total amount of heat energy required when heat sterilization control including the series of processes is performed multiple times.

[0047] Specifically, before the object heating step, a preheating step is performed in which the low-temperature sterilization tank 1 and the retort pouch Rp (object to be sterilized) are heated. This preheating step reduces the amount of heat absorbed by the sterilization tank 1 from the high-temperature water Hth during the object heating step, and makes it easier for the high-temperature water Hth to raise the temperature of the retort pouch Rp to the heat sterilization temperature Tst at which heat sterilization is performed.

[0048] In the heat sterilization control of this embodiment, as shown in Fig. 2, the medium-temperature water Htm, whose temperature has been raised (to about 90°C) by recovering heat in the medium-temperature water heat recovery step from the high-temperature sterilization tank 1 and the retort pouch Rp (object to be sterilized) after heat sterilization in the first heat sterilization control, is used for preheating in the second heat sterilization control, and the temperature of the medium-temperature water Htm is lowered from about 90°C to about 50°C. Then, the heat recovered in the second heat sterilization control is used for preheating in the third heat sterilization control, and similar utilization of the recovered heat is repeated from the second time onwards.

[0049] As a result, the thermal energy required for heating to perform preheating is obtained from the high-temperature sterilization tank 1 and retort pouches Rp (objects to be sterilized), which would normally be discharged via the cooling water Cw in the object cooling step. This reduces the total amount of thermal energy required when heat sterilization control including a series of processes is performed multiple times.

[0050] (Details of Heat Sterilization Control of This Embodiment) Hereinafter, details of the heat sterilization control including the preheating step and the medium-temperature water heat recovery step of this embodiment will be described with reference to FIGS. 3 to 22.

[0051] As shown in Fig. 3, the heat sterilization control according to this embodiment is a control that sequentially performs a carry-in process, a preheating process (preheating control), an object heating process (sterilization object heat sterilization control), a high-temperature water heat recovery process (high-temperature water heat recovery control), a medium-temperature water heat recovery process (medium-temperature water heat recovery control), an object cooling process (sterilization object cooling control), and a carry-out process. The preheating process includes each of a medium-temperature water injection process, a medium-temperature water circulation process, and a medium-temperature water recovery process. The object heating process includes each of a high-temperature water injection process, a temperature increase process, and a heat sterilization process. The medium-temperature water heat recovery process includes each of a medium-temperature water injection process, a medium-temperature water circulation process, and a medium-temperature water recovery process. The object cooling process includes each of a cooling water supply process, a cooling process, and a cooling water recovery process.

[0052] In contrast to the heat sterilization control of this embodiment, which includes the steps described above, the heat sterilization control of the comparative example (corresponding to a conventional example) shown in Figure 4 performs control over the retort pouch carry-in and carry-out steps, and control over the retort pouch heat sterilization step, high-temperature hydrothermal heat recovery step, and cooling step. In other words, the heat sterilization device that performs the heat sterilization control of this comparative example does not have a medium-temperature tank that stores medium-temperature water, and does not perform control of preheating and heat recovery using medium-temperature water.

[0053] As described above, among the above-described multiple steps of the heat sterilization control of this embodiment, the preheating step and the medium-temperature water heat recovery step are configurations that are different from the heat sterilization control of the comparative example. These will be described in detail below.

[0054] <Preparation of Hot Water> First, as shown in FIG. 5, high-temperature water Hth is prepared in advance before the carrying-in step.

[0055] Specifically, the control unit 12 performs control to form the hot water preparatory circuit Ci1 by closing the flow path switching valves 5g, 6e, and 8b and opening the flow path switching valves 6d and 7b. The control unit 12 then performs control to prepare high-temperature water Hth by heating the circulating coolant Cw through the hot water preparatory circuit Ci1 by heat exchange with steam in the heat exchanger 11 while circulating the coolant Cw supplied from the coolant source 200 through the hot water preparatory circuit Ci1 using the circulation pump 5f. Here, the hot water preparatory circuit Ci1 includes an upstream pipe 5c, a downstream pipe 5d, a common pipe 6a, a branch pipe 6b, a connecting pipe 7a, and a connecting pipe 8a. In the hot water preparatory circulation path Ci1, the cooling water Cw flows through the connecting pipe 7a, the connecting pipe 8a, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipe 6b in this order.

[0056] <Preparation of Medium-Temperature Water> Furthermore, as shown in FIG. 6, before the carrying-in step, medium-temperature water Htm is prepared in advance.

[0057] Specifically, after preparing high-temperature water Hth, the control unit 12 closes the flow path switching valves 5g, 6d, and 7b and opens the flow path switching valves 6e and 8b to form the medium-temperature water preparatory circuit Ci2. The control unit 12 then circulates cooling water Cw supplied from the cooling water source 200 through the medium-temperature water preparatory circuit Ci2 using the circulation pump 5f, while heating the circulating cooling water Cw through heat exchange with steam in the heat exchanger 11, thereby preparing medium-temperature water Htm (approximately 90°C). The medium-temperature water preparatory circuit Ci2 includes an upstream pipe 5c, a downstream pipe 5d, a common pipe 6a, a branch pipe 6c, and a connecting pipe 8a. In the medium-temperature water preparatory circulation path Ci2, the cooling water Cw flows through the connecting pipe 8a, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipe 6c in this order.

[0058] 7, after the medium-temperature water Htm and the high-temperature water Hth are prepared, the carry-in process is carried out. In the carry-in process, trays Tr on which a plurality of retort pouches Rp are placed are stacked in multiple layers and carried into the sterilization tank 1 by a user operation.

[0059] 8, before the retort pouches Rp are thermally sterilized with high-temperature water Hth, the control unit 12 controls the preheating of the sterilization tank 1 and the retort pouches Rp using medium-temperature water Htm supplied from the medium-temperature water tank 4. As a result, the sterilization tank 1 is preheated with the medium-temperature water Htm before the high-temperature water Hth is injected into the sterilization tank 1, thereby suppressing a sudden temperature change Tch1 in the sterilization tank 1 (see the comparative example in FIG. 4).

[0060] Specifically, the control unit 12 controls the formation of the medium-temperature water injection path Sp1 by closing the flow path switching valves 6d, 6e, and 7b and opening the flow path switching valves 5g and 8b. The control unit 12 then controls the circulation pump 5f to inject the medium-temperature water Htm in the medium-temperature water tank 4 into the sterilization tank 1 via the medium-temperature water injection path Sp1 (the medium-temperature water injection process (see FIG. 3)). The medium-temperature water injection path Sp1 includes an upstream conduit 5c, a downstream conduit 5d, and a connecting conduit 8a. In the medium-temperature water injection path Sp1, the medium-temperature water Htm flows through the connecting conduit 8a, the upstream conduit 5c, and the downstream conduit 5d in this order.

[0061] In this way, the control unit 12 controls the supply of medium-temperature water Htm to the sterilization tank 1 through the upstream pipe 5c, the downstream pipe 5d, and the connecting pipe 8a during preheating.

[0062] As shown in Fig. 9, after injecting the medium-temperature water Htm, the control unit 12 closes the flow path switching valves 6d, 6e, 7b, and 8b and opens the flow path switching valve 5g, thereby forming the medium-temperature water circulation path Ci3. The control unit 12 then performs preheating control by circulating the medium-temperature water Htm to the sterilization tank 1 through the medium-temperature water circulation path Ci3 using the circulation pump 5f without heat exchange in the heat exchanger 11 (the medium-temperature water circulation step (see Fig. 3)). The medium-temperature water circulation path Ci3 includes a circulation path 5 (discharge pipe 5a, discharge pipe 5b, upstream pipe 5c, and downstream pipe 5d). In the medium-temperature water circulation path Ci3, the medium-temperature water Htm flows through the discharge pipes 5a and 5b, the upstream pipe 5c, and the downstream pipe 5d, in that order.

[0063] At this time, the control unit 12 controls the release of the medium-temperature water Htm supplied from the medium-temperature water tank 4 toward the retort pouches Rp in preheating the sterilization tank 1. Here, in the preheating step, the temperature of the medium-temperature water Htm has dropped to the post-preheating temperature (approximately 50°C) by applying heat to the sterilization tank 1 and the retort pouches Rp.

[0064] As shown in Figure 10, the control unit 12 circulates the medium-temperature water Htm for a predetermined time, and then controls the medium-temperature water Htm in the preheated sterilization tank 1 to be recovered and stored in the medium-temperature water tank 4 via the medium-temperature water recovery path Re1.

[0065] Specifically, after circulating the medium-temperature water Htm for a predetermined time, the control unit 12 closes the flow path switching valves 5g, 6d, 7b, and 8b and opens the flow path switching valve 6e, thereby forming the medium-temperature water return path Re1. The control unit 12 then performs recovery control to recover the medium-temperature water Htm into the medium-temperature water tank 4 via the medium-temperature water return path Re1 using the circulation pump 5f (the medium-temperature water recovery step (see FIG. 3)). The medium-temperature water return path Re1 includes the discharge pipes 5a, 5b, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipes 6c. In the medium-temperature water recovery passage Re1, the medium-temperature water Htm flows through each of the discharge pipes 5a and 5b, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipe 6c in this order.

[0066] Then, the control unit 12 recovers the medium-temperature water Htm in the sterilization tank 1 into the medium-temperature water tank 4 via the medium-temperature water recovery path Re1, and then performs the object heating step for the retort pouch Rp. At this time, the water level sensor 1c confirms that the medium-temperature water Htm has been discharged from the sterilization tank 1, thereby preventing the temperature of the high-temperature water Hth from decreasing due to the medium-temperature water Htm.

[0067] <Process for Heating Object> As shown in Figures 11 and 12, the control unit 12 preheats the retort pouch Rp with medium-temperature water Htm, and then controls the heat sterilization of the retort pouch Rp using high-temperature water Hth supplied from the high-temperature water tank 3.

[0068] Specifically, as shown in Fig. 11 , the control unit 12 closes the flow path switching valves 6d, 6e, and 8b and opens the flow path switching valves 5g and 7b to form the hot water injection path Sp2. The control unit 12 then controls the circulation pump 5f to inject the medium-temperature water Htm in the high-temperature water tank 3 into the sterilization tank 1 via the hot water injection path Sp2 (the high-temperature water injection process (see Fig. 3 )). The hot water injection path Sp2 includes an upstream pipe 5c, a downstream pipe 5d, a connecting pipe 7a, and a connecting pipe 8a. In the hot water injection path Sp2, the high-temperature water Hth flows through the connecting pipe 7a, the connecting pipe 8a, the upstream pipe 5c, and the downstream pipe 5d in this order.

[0069] As shown in Fig. 12, after injecting high-temperature water Hth, the control unit 12 closes flow path switching valves 6d, 6e, 7b, and 8b and opens flow path switching valve 5g, thereby forming a temperature-raising / heat-sterilizing circuit Ci4. The control unit 12 then controls the circulation pump 5f to circulate the high-temperature water Hth through the temperature-raising / heat-sterilizing circuit Ci4 to the sterilization tank 1, while performing temperature-raising control to raise the temperature of the high-temperature water Hth to a heat-sterilizing temperature Tst (for example, higher than about 120°C) through heat exchange with steam in the heat exchanger 11 (temperature-raising step (see Fig. 3)). The temperature-raising / heat-sterilizing circuit Ci4 includes a circulation path 5 (discharge pipes 5a, 5b, upstream pipes 5c, and downstream pipes 5d). In the temperature-raising / heat-sterilizing circulation path Ci4, the high-temperature water Hth flows through each of the discharge pipes 5a and 5b, the upstream pipe 5c, and the downstream pipe 5d in that order. Note that the heat-sterilizing temperature Tst being higher than approximately 120°C is merely an example and varies depending on the type of object to be heat-sterilized.

[0070] In addition, the control unit 12 heats the high-temperature water Hth to the heat sterilization temperature Tst, and then circulates the high-temperature water Hth to the sterilization tank 1 via the temperature-raising / heat sterilization circulation path Ci4 using the circulation pump 5f, while performing heat sterilization control to maintain the high-temperature water Hth at the heat sterilization temperature Tst by heat exchange with steam in the heat exchanger 11 (heat sterilization process).

[0071] 13 , after heat sterilization using high-temperature water Hth, the control unit 12 performs control for a predetermined time such that the high-temperature water Hth in the sterilization tank 1 after heat sterilization is recovered and stored in the high-temperature water tank 3 via the hot water recovery path Re2. The high-temperature water heat recovery step is a step of recovering the high-temperature water Hth in the high-temperature water tank 3 while maintaining the temperature after heat sterilization.

[0072] Specifically, after heat sterilization using high-temperature water Hth for a predetermined time, the control unit 12 closes the flow path switching valves 5g, 6e, 7b, and 8b and opens the flow path switching valve 6d, thereby forming a hot water recovery path Re2. The control unit 12 then performs recovery control to recover the high-temperature water Hth into the high-temperature water tank 3 via the hot water recovery path Re2 using the circulation pump 5f (high-temperature water heat recovery process (see FIG. 3)). The hot water recovery path Re2 includes the discharge pipe 5a, the discharge pipe 5b, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipe 6b. In the hot water recovery path Re2, the high-temperature water Hth flows through the discharge pipe 5a, the discharge pipe 5b, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipe 6b, in this order.

[0073] Then, the control unit 12 recovers the high-temperature water Hth discharged from the sterilization tank 1 into the high-temperature water tank 3 via the hot water recovery path Re2, and then performs the medium-temperature water heat recovery step for the sterilization tank 1 and the retort pouch Rp. That is, the control unit 12 controls the medium-temperature water heat recovery step in a state where the high-temperature water Hth after thermal sterilization has been discharged from the sterilization tank 1. At this time, the water level sensor 1c confirms that the high-temperature water Hth has been discharged from the sterilization tank 1, thereby preventing the temperature of the medium-temperature water Htm from rising due to the high-temperature water Hth.

[0074] 14 to 16, before cooling the retort pouches Rp with cooling water Cw, the control unit 12 performs a medium-temperature water heat recovery step in which heat is recovered from the sterilization tank 1 and the retort pouches Rp using medium-temperature water Htm supplied from the medium-temperature water tank 4. In this way, heat from the sterilization tank 1 is recovered using the medium-temperature water Htm before cooling water Cw is injected into the sterilization tank 1, thereby suppressing a sudden temperature change Tch2 in the sterilization tank 1 (see the comparative example in FIG. 4).

[0075] Specifically, as shown in Fig. 14, the control unit 12 closes the flow path switching valves 6d, 7b, and 6e and opens the flow path switching valves 5g and 8b, thereby forming the medium-temperature water injection path Sp3. The control unit 12 then controls the circulation pump 5f to inject the medium-temperature water Htm in the medium-temperature water tank 4 into the sterilization tank 1 via the medium-temperature water injection path Sp3 (the medium-temperature water injection process (see Fig. 3)). The medium-temperature water injection path Sp3 includes an upstream conduit 5c, a downstream conduit 5d, and a connecting conduit 8a. In the medium-temperature water injection path Sp3, the medium-temperature water Htm flows through the connecting conduit 8a, the upstream conduit 5c, and the downstream conduit 5d in this order.

[0076] As shown in FIG. 15 , after injecting the medium-temperature water Htm, the control unit 12 closes the flow path switching valves 6d, 6e, 7b, and 8b and opens the flow path switching valve 5g, thereby forming the heat recovery circuit Ci5. The control unit 12 then performs medium-temperature water heat recovery control by circulating the medium-temperature water Htm to the sterilization tank 1 through the heat recovery circuit Ci5 using the circulation pump 5f without heat exchange in the heat exchanger 11 (the medium-temperature water circulation process (see FIG. 3 )). The heat recovery circuit Ci5 includes a circulation path 5 (discharge pipe 5a, discharge pipe 5b, upstream pipe 5c, and downstream pipe 5d). In the heat recovery circuit Ci5, the medium-temperature water Htm flows through the discharge pipes 5a and 5b, the upstream pipe 5c, and the downstream pipe 5d, in that order.

[0077] At this time, the control unit 12 controls the release of the medium-temperature water Htm supplied from the medium-temperature water tank 4 toward the retort pouches Rp in the heat recovery of the sterilization tank 1. Here, in the medium-temperature water circulation process, the temperature of the medium-temperature water Htm rises to the post-heat recovery temperature (approximately 90°C) by removing heat from the sterilization tank 1, the retort pouches Rp, etc.

[0078] As shown in Figure 16, the control unit 12 circulates the medium-temperature water Htm for a predetermined time, and then controls the medium-temperature water Htm in the sterilization tank 1 after heat recovery to be recovered and stored in the medium-temperature water tank 4 via the medium-temperature water recovery path Re3.

[0079] Specifically, after circulating the medium-temperature water Htm for a predetermined time, the control unit 12 closes the flow path switching valves 5g, 6d, 7b, and 8b and opens the flow path switching valve 6e, thereby forming the medium-temperature water return path Re3. The control unit 12 then performs recovery control to recover the medium-temperature water Htm into the medium-temperature water tank 4 via the medium-temperature water return path Re3 using the circulation pump 5f (the medium-temperature water recovery step (see FIG. 3)). The medium-temperature water return path Re3 includes the discharge pipes 5a, 5b, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipes 6c. In the medium-temperature water recovery passage Re3, the medium-temperature water Htm flows through each of the discharge pipes 5a and 5b, the upstream pipe 5c, the downstream pipe 5d, the common pipe 6a, and the branch pipe 6c in this order.

[0080] In this way, before the object cooling step of the retort pouch Rp with the cooling water Cw, the control unit 12 performs a medium-temperature water heat recovery step of recovering heat from the sterilization tank 1 after thermal sterilization using the medium-temperature water Htm supplied from the medium-temperature water tank 4, and also controls the medium-temperature water Htm used in the medium-temperature water heat recovery step to be stored in the medium-temperature water tank 4. That is, the control unit 12 controls the medium-temperature water Htm in the sterilization tank 1 after heat recovery to be recovered and stored in the medium-temperature water tank 4 via the discharge pipe 5a, discharge pipe 5b, upstream pipe 5c, downstream pipe 5d, common pipe 6a, and branch pipe 6c.

[0081] The control unit 12 then recovers the medium-temperature water Htm in the sterilization tank 1 into the medium-temperature water tank 4 via the medium-temperature water recovery path Re3, and then performs a cooling process for the retort pouches Rp. At this time, the water level sensor 1c confirms that the medium-temperature water Htm has been discharged from the sterilization tank 1, thereby preventing the temperature of the cooling water Cw from rising due to the medium-temperature water Htm.

[0082] <Process for cooling object> As shown in Figures 17 to 19, after recovering heat from the retort pouch Rp using medium-temperature water Htm, the control unit 12 performs a cooling process to cool the retort pouch Rp and the sterilization tank 1 using cooling water Cw supplied from the cooling water source 200 (see Figure 1).

[0083] Specifically, as shown in Fig. 17 , the control unit 12 closes the flow path switching valves 6d, 6e, 7b, and 8b and opens the flow path switching valve 5g, thereby forming the cooling water injection path Sp4. The control unit 12 then controls the circulation pump 5f to inject cooling water Cw supplied from the cooling water source 200 into the sterilization tank 1 via the cooling water injection path Sp4 (cooling water injection process (see Fig. 3 )). The cooling water injection path Sp4 includes a circulation path 5 (discharge pipe 5a, discharge pipe 5b, upstream pipe 5c, and downstream pipe 5d). In the cooling water injection path Sp4, the cooling water Cw flows through the upstream pipe 5c, downstream pipe 5d, discharge pipe 5a, and discharge pipe 5b, in this order.

[0084] 18, after injecting cooling water Cw, the control unit 12 closes flow path switching valves 6d, 6e, 7b, and 8b and opens flow path switching valve 5g, thereby forming a cooling circuit Ci6. Then, the control unit 12 circulates the cooling water Cw through the cooling circuit Ci6 using a circulation pump 5f, while performing cooling control to cool the heated cooling water Cw, which has been removed from the retort pouches Rp and the sterilization tank 1 by heat exchange with the cooling water in a heat exchanger 11 (cooling step (see FIG. 3)). Here, the cooling circuit Ci6 includes a circulation path 5 (discharge pipes 5a, 5b, upstream pipes 5c, and downstream pipes 5d). In the cooling circulation path Ci6, the cooling water Cw flows through each of the discharge pipes 5a and 5b, the upstream pipe 5c, and the downstream pipe 5d in this order.

[0085] 19 , after cooling with cooling water Cw for a predetermined time, the control unit 12 controls the circulation pump 5f to recover the cooled cooling water Cw in the sterilization tank 1 through the cooling water recovery line Re4 (cooling water recovery process). Here, the cooling water recovery line Re4 has discharge lines 5a, 5b, and an upstream line 5c. In the cooling water recovery line Re4, the cooling water Cw flows through the discharge lines 5a, 5b, and the upstream line 5c in that order.

[0086] <Carry-Out Step> In the carry-out step, as shown in FIG. 20, the cooled retort pouches Rp are carried out of the sterilization tank 1 by the user.

[0087] Then, the next heat sterilization control is performed on the multiple retort pouches Rp. At this time, before heating the retort pouches Rp with high-temperature water Hth, the control unit 12 performs a preheating process in which the sterilization tank 1 is preheated using the medium-temperature water Htm that was heated during the medium-temperature water heat recovery process (medium-temperature water heat recovery control) and stored in the medium-temperature water tank 4. As a result, in the heat sterilization control of this embodiment, the heat removed from the retort pouches Rp and the sterilization tank 1 during the medium-temperature water heat recovery process is utilized, thereby suppressing heat loss. Furthermore, since only a slight reheating (for example, about 1 to 2°C) is required during the advance preparation of the medium-temperature water Htm shown in FIG. 6 , the amount of heat required to heat the medium-temperature water Htm and the time required to heat the medium-temperature water Htm are suppressed after the first heat sterilization control.

[0088] Such heat sterilization control is performed multiple times a day. The medium-temperature water Htm stored in the medium-temperature water tank 4 is reused and then discharged from the medium-temperature water tank 4. Control is then performed to store new medium-temperature water Htm in the medium-temperature water tank 4 (see FIG. 6 ). The timing for replacing the medium-temperature water Htm is set appropriately by the user, either once a day or every few days. This suppresses an increase in water consumption due to the use of medium-temperature water Htm, compared to when medium-temperature water Htm is prepared for each heating control.

[0089] (Comparison between heat sterilization control of comparative example and heat sterilization control of this embodiment) Figure 21 shows a graph in which the graph of heat sterilization control of the comparative example (corresponding to the conventional example) shown in Figure 4 is superimposed on the graph of heat sterilization control of this embodiment shown in Figure 3. Here, the graph of heat sterilization control of the comparative example is shown by a thick two-dot chain line. Moreover, the graph of heat sterilization control of this embodiment is shown by a thick solid line.

[0090] Comparing the heat sterilization control of the comparative example with the heat sterilization control of the present embodiment, the operation time of the heat sterilization control of the present embodiment increases by time Tlag because the preheating step and the medium-temperature water heat recovery step are added.

[0091] However, the time Ui of the temperature increase step of the object heating step in the heat sterilization control of this embodiment is shorter than the time Ue of the temperature increase step of the object heating step in the heat sterilization control of the comparative example. This is because in the heat sterilization control of this embodiment, the initial temperature of the object heating step is higher due to the preheating step than the initial temperature of the object heating step in the heat sterilization control of the comparative example. Furthermore, the time Di of the object cooling step in the heat sterilization control of this embodiment is shorter than the time De of the object cooling step in the heat sterilization control of the comparative example. This is because in the heat sterilization control of this embodiment, the initial temperature of the object cooling step is lower due to the medium-temperature water heat recovery step than the initial temperature of the object cooling step in the heat sterilization control of the comparative example.

[0092] Furthermore, by making the time Ui for the temperature raising step shorter than the time Ue for the temperature raising step, the amount of steam required to raise the temperature of the high-temperature water Hth is reduced. Furthermore, although the medium-temperature water Htm is heated with steam in advance preparation of the medium-temperature water Htm, by reusing the medium-temperature water Htm and by reducing the amount of steam required to raise the temperature of the high-temperature water Hth, when heat sterilization control is performed multiple times, the thermal energy required for heat sterilization control is reduced compared to when heat sterilization control is performed multiple times in the comparative example.

[0093] Furthermore, in the heat sterilization control of this embodiment, since medium-temperature water Htm is injected into the sterilization tank 1 after the carry-in step, the temperature change Ti1 of the sterilization tank 1 after the carry-in step is smaller by the temperature difference Td1 than the temperature change Te1 of the sterilization tank 1 after the carry-in step in the comparative example. Furthermore, in the heat sterilization control, since medium-temperature water Htm is injected into the sterilization tank 1 after the high-temperature hydrothermal heat recovery step, the temperature change Ti2 of the sterilization tank 1 after the high-temperature hydrothermal heat recovery step is smaller by the temperature difference Td2 than the temperature change Te2 of the sterilization tank 1 after the carry-in step in the comparative example. This suppresses sudden temperature changes in the sterilization tank 1, thereby suppressing expansion and contraction of the sterilization tank 1.

[0094] (Heat sterilization method) The heat sterilization method performed in the above-described heat sterilization device 100 will be described with reference to Figures 7, 9, 12, 15, 18, 20 and 22. The heat sterilization method is a method executed by the control unit 12 based on a heat sterilization program.

[0095] Here, high-temperature water Hth and medium-temperature water Htm are prepared prior to the preheating step of step S1 shown in Fig. 22. In the following description, it is assumed that the medium-temperature water Htm is heated during the above-described medium-temperature water heat recovery step (medium-temperature water heat recovery control) and stored in the medium-temperature water tank 4. Then, a loading step is performed in which a user loads trays Tr, each carrying a plurality of retort pouches Rp, stacked in multiple layers into the sterilization tank 1 (see Fig. 7).

[0096] In step S1 shown in Fig. 22, a preheating step is performed after the carrying-in step. The preheating step is a step in which the sterilization tank 1 is preheated using medium-temperature water Htm heated during heat recovery from the sterilization tank 1 before high-temperature water Hth for heat-sterilizing the retort pouches Rp is supplied to the sterilization tank 1 (see Fig. 9).

[0097] In step S2, an object heating step is performed. The object heating step is a step of supplying high-temperature water Hth to the sterilization tank 1, which performs thermal sterilization using high-temperature water Hth, to heat sterilize the retort pouch Rp in the sterilization tank 1 (see FIG. 12).

[0098] In step S3, a high-temperature hydrothermal recovery step is performed. In this step, after heat sterilization using high-temperature water Hth, the high-temperature water Hth in the sterilization tank 1 after heat sterilization is recovered and stored in the high-temperature water tank 3 via the hot water recovery passage Re2 (see FIG. 13 ).

[0099] In step S4, a medium-temperature water heat recovery process is performed. The medium-temperature water heat recovery process is a process in which, before cooling the retort pouch Rp with the cooling water Cw, heat is recovered from the sterilization tank 1 after thermal sterilization using medium-temperature water Htm, which has a temperature higher than that of the cooling water Cw but lower than that of the high-temperature water Hth and which has been produced separately from the high-temperature water Hth (see FIG. 15 ).

[0100] In step S5, an object cooling step is performed. The object cooling step is a step of cooling the heat-sterilized retort pouch Rp with cooling water Cw after heat recovery from the sterilization tank 1 (see FIG. 18). Then, after step S5, the heat sterilization method ends.

[0101] After the heat sterilization method is completed, a carrying-out step is carried out in which the cooled retort pouch Rp is carried out by the user from the sterilization tank 1 (see FIG. 20).

[0102] (Retort Pouch) The retort pouch Rp produced by such a heat sterilization bath method is subjected to heat sterilization treatment by the heat sterilization device 100.

[0103] Specifically, the retort pouch Rp (object to be sterilized) is heat sterilized by a heat sterilization device 100 having a storage space 1d for storing the retort pouch Rp (object to be sterilized) therein to be heat sterilized with high-temperature water Hth (high-temperature fluid), a sterilization tank 1 to which high-temperature water Hth (high-temperature fluid) for heat sterilizing the retort pouch Rp (object to be sterilized) and cooling water Cw for cooling the retort pouch Rp (object to be sterilized) that has been heat sterilized with the high-temperature water Hth (high-temperature fluid) are supplied, and a control unit 12 for performing medium-temperature water heat recovery control to recover heat from the sterilization tank 1 after heat sterilization using medium-temperature water Htm that has a temperature higher than the cooling water Cw but lower than the temperature of the high-temperature water Hth (high-temperature fluid) before cooling the retort pouch Rp (object to be sterilized) with the cooling water Cw.

[0104] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0105] In this embodiment, as described above, the heat sterilization apparatus 100 is equipped with a control unit 12 that performs a medium-temperature water heat recovery process (medium-temperature water heat recovery control) to recover heat from the sterilization tank 1 after the object heating process (heat sterilization control) using medium-temperature water Htm that is generated separately from the high-temperature water Hth and has a temperature higher than the cooling water Cw but lower than the high-temperature water Hth, before cooling the retort pouch Rp (object to be sterilized) with the cooling water Cw. In this way, by recovering heat from the sterilization tank 1 after heat sterilization using medium-temperature water Htm generated separately from the high-temperature water Hth, it is possible to prevent the temperature of the high-temperature water Hth from decreasing, and therefore it is possible to prevent an increase in the time required to heat the high-temperature water Hth to the heat sterilization temperature Tst during the next heat sterilization after the heat recovery. Furthermore, before cooling the retort pouches Rp (objects to be sterilized) with the cooling water Cw, the sterilization tank 1 after the object heating step (heat sterilization control) can be cooled with medium-temperature water Htm at a temperature higher than that of the cooling water Cw, thereby suppressing a sudden temperature change (sudden temperature drop) in the sterilization tank 1 after the object heating step (heat sterilization control). As a result, the degree of expansion and contraction of the sterilization tank 1 can be reduced, and unlike when large expansions and contractions are repeated, metal fatigue due to thermal stress can be suppressed, and a decrease in the durability of the sterilization tank 1 (shortening of its lifespan) can be suppressed.

[0106] Furthermore, in this embodiment, as described above, before cooling the retort pouch Rp (object to be sterilized) with the cooling water Cw, the control unit 12 performs a medium-temperature water heat recovery process (medium-temperature water heat recovery control) to recover heat from the sterilization tank 1 after the object heating process (heat sterilization control) using medium-temperature water Htm that is generated separately from the high-temperature water Hth and has a temperature higher than that of the cooling water Cw but lower than that of the high-temperature water Hth. In this way, by recovering the heat from the sterilization tank 1 after the object heating process (heat sterilization control) using the medium-temperature water Htm in the medium-temperature water heat recovery process (medium-temperature water heat recovery control), it is possible to suppress heat loss of the heat imparted to the retort pouch Rp and the sterilization tank 1 during the object heating process (heat sterilization control).

[0107] Furthermore, in this embodiment, as described above, the control unit 12 performs the medium-temperature water heat recovery step (medium-temperature water heat recovery control) in a state in which the high-temperature water Hth after thermal sterilization has been discharged from the sterilization tank 1. As a result, heat recovery using the high-temperature water Hth is performed simply by discharging the high-temperature water Hth, and therefore a dedicated heat exchanger and water supply tank for heat recovery using the high-temperature water Hth are not required, and therefore it is possible to suppress an increase in the size of the device due to heat recovery using the high-temperature water Hth.

[0108] Furthermore, in this embodiment, as described above, the heat sterilization apparatus 100 includes the medium-temperature water tank 4 in which medium-temperature water Htm is stored. The control unit 12 is configured to perform a medium-temperature water heat recovery process (medium-temperature water heat recovery control) in which the medium-temperature water Htm supplied from the medium-temperature water tank 4 is used to recover heat from the sterilization tank 1 after heat sterilization before cooling the retort pouches Rp (objects to be sterilized) with cooling water Cw, and to store the medium-temperature water Htm used in the medium-temperature water heat recovery process (medium-temperature water heat recovery control) in the medium-temperature water tank 4. Thus, by storing the medium-temperature water Htm in the medium-temperature water tank 4, the medium-temperature water Htm can be easily supplied to the sterilization tank 1 after heat sterilization during heat recovery, and by storing the medium-temperature water Htm used for heat recovery in the medium-temperature water tank 4 without discharging it, the recovered heat can be easily reused.

[0109] Furthermore, in this embodiment, as described above, the control unit 12 performs a preheating process (preheating control) in which the sterilization tank 1 is preheated using the medium-temperature water Htm heated during the medium-temperature water heat recovery process (medium-temperature water heat recovery control) and stored in the medium-temperature water tank 4 before heating the retort pouch Rp (object to be sterilized) with the high-temperature water Hth. By preheating the sterilization tank 1 using the heated medium-temperature water Htm used for heat recovery, the initial temperature of the sterilization tank 1 at the start of the object heating process (heat sterilization control) can be increased. Therefore, compared to when preheating is not performed, the amount of heat imparted to the high-temperature water Hth during the temperature increase to the temperature at which the high-temperature water Hth is to be heated during the object heating process (heat sterilization control) can be reduced. In other words, by using the medium-temperature water Htm, the recovered heat can be effectively used for preheating. As a result, the increase in thermal energy required in the heat sterilization apparatus 100 when preheating is performed can be reduced, thereby reducing the amount of (high-temperature) steam used to heat the high-temperature water Hth.

[0110] Furthermore, in this embodiment, as described above, the heat sterilization apparatus 100 includes the circulation path 5, common pipe 6a, branch pipe 6c, and connecting pipe 8a (first connecting path) that connect the sterilization tank 1 and the medium-temperature water tank 4. The control unit 12 controls the recovery and storage of the medium-temperature water Htm in the sterilization tank 1 after heat recovery in the medium-temperature water tank 4 via the discharge pipe 5a, discharge pipe 5b, upstream pipe 5c, downstream pipe 5d, common pipe 6a, and branch pipe 6c (first connecting path), and controls the supply of medium-temperature water Htm to the sterilization tank 1 via the upstream pipe 5c, downstream pipe 5d, and connecting pipe 8a (first connecting path) during preheating. This makes it possible to easily store the medium-temperature water Htm after heat recovery in the medium-temperature water tank 4 and supply the medium-temperature water Htm from the medium-temperature water tank 4 to the sterilization tank 1 during preheating using the common pipe 6a and the branch pipe 6c (first connection path).

[0111] Furthermore, in this embodiment, as described above, the control unit 12 controls the release of medium-temperature water Htm supplied from the medium-temperature water tank 4 toward the retort pouch Rp (object to be sterilized) during both preheating of the sterilization tank 1 and heat recovery from the sterilization tank 1. As a result, when preheating the low-temperature sterilization tank 1, the released medium-temperature water Htm hits the retort pouch Rp (object to be sterilized), lowering the temperature of the medium-temperature water Htm, and the lowered-temperature medium-temperature water Htm can be applied to the sterilization tank 1, thereby suppressing a sudden change in temperature in the sterilization tank 1. Furthermore, when recovering heat from the sterilization tank 1, the released medium-temperature water Htm hits the retort pouch Rp (object to be sterilized), raising the temperature of the medium-temperature water Htm, and the increased-temperature medium-temperature water Htm can be applied to the high-temperature sterilization tank 1 during heat recovery, thereby suppressing a sudden change in temperature in the sterilization tank 1. As a result, during both preheating of the sterilization tank 1 and heat recovery of the sterilization tank 1, the decrease in durability of the sterilization tank 1 due to increased thermal stress caused by sudden temperature changes can be further suppressed.

[0112] Furthermore, in this embodiment, as described above, the heat sterilization apparatus 100 includes the high-temperature water tank 3 that recovers and stores high-temperature water Hth, which is high-temperature water Hth stored in the sterilization tank 1 after the object heating step (heat sterilization control). The heat sterilization apparatus 100 includes a common pipe 6a and a branch pipe 6b (second connection path) that connect the sterilization tank 1 and the high-temperature water tank 3. The control unit 12 recovers the high-temperature water Hth discharged from the sterilization tank 1 after the object heating step (heat sterilization control) of the retort pouch Rp (sterilization object) is completed into the high-temperature water tank 3 via the common pipe 6a and the branch pipe 6b (second connection path), and then performs the medium-temperature water heat recovery step (medium-temperature water heat recovery control) of the sterilization tank 1. As a result, by recovering the high-temperature water Hth in the sterilization tank 1 through a dedicated common pipe 6a and a branch pipe 6b (second connection path) that connect the sterilization tank 1 and the high-temperature water tank 3 to each other, it is possible to prevent the heat of the high-temperature water Hth from being lost after the object heating process (heat sterilization control), and therefore it is possible to prevent the temperature of the high-temperature water Hth recovered in the high-temperature water tank 3 from decreasing.

[0113] Furthermore, in this embodiment, as described above, the heat sterilization apparatus 100 is provided with a circulation path 5 including a circulation pump 5f that discharges each of the cooling water Cw, high-temperature water Hth, and medium-temperature water Htm discharged from the sterilization tank 1 and circulates them back into the sterilization tank 1. The control unit 12 performs a medium-temperature water heat recovery process (medium-temperature water heat recovery control) by circulating the medium-temperature water Htm back into the sterilization tank 1 via the circulation path 5 using the circulation pump 5f. This allows the circulation path 5 used in each of the object heating process (heat sterilization control) and the object cooling process (cooling control) to be shared in the medium-temperature water heat recovery process (medium-temperature water heat recovery control), thereby preventing the structure of the heat sterilization apparatus 100 from becoming more complex and larger due to an increase in the number of paths.

[0114] Furthermore, in this embodiment, as described above, the retort pouch Rp (object to be sterilized) is heat sterilized by a heat sterilization device 100 having an accommodation space 1d for accommodating the retort pouch Rp (object to be sterilized) therein to be heat sterilized with high-temperature water Hth, a sterilization tank 1 to which high-temperature water Hth is supplied for performing an object heating step (heat sterilization control) on the object to be sterilized and cooling water Cw for cooling the retort pouch Rp (object to be sterilized) that has been subjected to the object heating step (heat sterilization control) with the high-temperature water Hth, and a control unit 12 for performing a medium-temperature water heat recovery step (medium-temperature water heat recovery control) that recovers heat from the sterilization tank 1 after the object heating step (heat sterilization control) using medium-temperature water Htm that is generated separately from the high-temperature water Hth and has a temperature higher than the cooling water Cw but lower than the high-temperature water Hth, before cooling the retort pouch Rp (object to be sterilized) with the cooling water Cw. As a result, by recovering heat from the sterilization tank 1 after heat sterilization using medium-temperature water Htm that is produced separately from the high-temperature water Hth, it is possible to prevent the temperature of the high-temperature water Hth from decreasing, and therefore it is possible to prevent the time required to raise the temperature of the high-temperature water Hth to the heat sterilization temperature Tst during the next heat sterilization after heat recovery from becoming too long.It is also possible to provide a retort pouch Rp (object to be sterilized) that has been heat sterilized using the heat sterilization device 100, which can prevent a decrease in the durability of the sterilization tank 1 due to an increase in thermal stress caused by a sudden temperature change.

[0115] Furthermore, in this embodiment, as described above, the heat sterilization method includes step S4 of recovering heat from the sterilization tank 1 after the object heating step (heat sterilization control) using medium-temperature water Htm, which is generated separately from the high-temperature water Hth and has a temperature higher than the cooling water Cw but lower than the high-temperature water Hth, before cooling the retort pouch Rp (the object to be sterilized) with the cooling water Cw. In this way, by recovering heat from the sterilization tank 1 after heat sterilization using medium-temperature water Htm generated separately from the high-temperature water Hth, it is possible to prevent the temperature of the high-temperature water Hth from decreasing. Therefore, it is possible to provide a heat sterilization method that can prevent an increase in the time required to heat the high-temperature water Hth to the heat sterilization temperature Tst during the next heat sterilization after heat recovery and that can prevent a decrease in the durability of the sterilization tank 1 due to an increase in thermal stress caused by a sudden temperature change.

[0116] Furthermore, in this embodiment, as described above, the heat sterilization method includes step S1 of preheating the sterilization tank 1 using medium-temperature water Htm heated during heat recovery in the sterilization tank 1 before supplying high-temperature water Hth, which is used to perform the object heating step (heat sterilization control) on the retort pouch Rp (sterilization object), to the sterilization tank 1. By preheating the sterilization tank 1, the initial temperature of the sterilization tank 1 at the start of the object heating step (heat sterilization control) can be increased, thereby reducing the amount of heat imparted to the high-temperature water Hth when raising the temperature of the high-temperature water Hth to the temperature at which the object heating step (heat sterilization control) is performed, compared to when preheating is not performed. Furthermore, by using the medium-temperature water Htm after the medium-temperature water heat recovery step (medium-temperature water heat recovery control) to preheat the sterilization tank 1, the heat of the sterilization tank 1 and the retort pouch Rp (sterilization object) after the object heating step (heat sterilization control) can be used to raise the temperature of the medium-temperature water Htm to the preheat temperature. As a result, when the sterilization tank 1 is preheated with the medium-temperature water Htm after the medium-temperature water heat recovery process (medium-temperature water heat recovery control), the thermal energy required in the heat sterilization device 100 due to the preheating can be reduced, and the amount of (high-temperature) steam used to raise the temperature of the high-temperature water Hth can be reduced accordingly.

[0117] Furthermore, in this embodiment, as described above, in the preheating step, the control unit 12 closes the flow path switching valves 6d, 6e, and 7b and opens the flow path switching valves 5g and 8b to form the medium-temperature water injection path Sp1, and then controls the circulation pump 5f to inject the medium-temperature water Htm in the medium-temperature water tank 4 into the sterilization tank 1 via the medium-temperature water injection path Sp1. This allows the injection of the medium-temperature water Htm from the medium-temperature water tank 4 into the sterilization tank 1 without using any pump other than the circulation pump 5f.

[0118] Furthermore, in this embodiment, as described above, in the preheating step, the control unit 12 closes the flow path switching valves 5g, 6d, 7b, and 8b and opens the flow path switching valve 6e to form the medium-temperature water recovery path Re1, and then performs recovery control using the circulation pump 5f to recover the medium-temperature water Htm through the medium-temperature water recovery path Re1 into the medium-temperature water tank 4. This makes it possible to recover the medium-temperature water Htm from the sterilization tank 1 into the medium-temperature water tank 4 without using a pump other than the circulation pump 5f.

[0119] Furthermore, in the present embodiment, as described above, in the medium-temperature water heat recovery step, the control unit 12 closes the flow path switching valves 6d, 7b, and 6e and opens the flow path switching valves 5g and 8b to form the medium-temperature water injection path Sp3, and then controls the circulation pump 5f to inject the medium-temperature water Htm in the medium-temperature water tank 4 into the sterilization tank 1 via the medium-temperature water injection path Sp3. This allows the injection of the medium-temperature water Htm from the medium-temperature water tank 4 into the sterilization tank 1 without using a pump other than the circulation pump 5f.

[0120] Furthermore, in the present embodiment, as described above, in the medium-temperature water heat recovery step, the control unit 12 closes the flow path switching valves 5g, 6d, 7b, and 8b and opens the flow path switching valve 6e to form the medium-temperature water recovery path Re3, and then performs recovery control using the circulation pump 5f to recover the medium-temperature water Htm through the medium-temperature water recovery path Re3 into the medium-temperature water tank 4. This makes it possible to recover the medium-temperature water Htm from the sterilization tank 1 to the medium-temperature water tank 4 without using a pump other than the circulation pump 5f.

[0121] Furthermore, in this embodiment, the supply path 6 is a conduit branching off from the circulation path 5 to supply high-temperature water Hth to the high-temperature water tank 3. The supply path 6 is also a conduit branching off from the circulation path 5 to supply medium-temperature water Htm to the medium-temperature water tank 4. The supply path 6 includes a common conduit 6a. The common conduit 6a is connected to the circulation path 5 and is a common conduit for the high-temperature water tank 3 and the medium-temperature water tank 4. As a result, when the sterilization tank 1 is preheated with the medium-temperature water Htm, the medium-temperature water Htm flows through the common conduit 6a, so that not only the sterilization tank 1 but also the common conduit 6a is preheated by the medium-temperature water Htm. Therefore, compared to a case where a common pipe is not used to connect the sterilization tank 1 to the high-temperature water tank 3 and the medium-temperature water tank 4, the common conduit 6a is also preheated when high-temperature water Hth is supplied to the sterilization tank 1 after preheating the sterilization tank 1, and therefore a rapid temperature rise can be suppressed not only in the sterilization tank 1 but also in the common conduit 6a. As a result, the risk of cracks occurring due to stress caused by a sudden temperature rise can be reduced not only in the sterilization tank 1 but also in the common pipe 6a. Furthermore, when recovering heat from the sterilization tank 1 using the medium-temperature water Htm, the medium-temperature water Htm flows through the common pipe 6a heated by the high-temperature water Hth when the high-temperature water Hth in the sterilization tank 1 is recovered to the high-temperature water tank 3, so that heat not only from the sterilization tank 1 but also from the common pipe 6a heated by the high-temperature water Hth is recovered by the medium-temperature water Htm. This makes it possible to recover heat from the common pipe 6a heated by the high-temperature water Hth, so that the temperature of the medium-temperature water Htm used to preheat the sterilization tank 1 next time can be made higher compared to when the common pipe 6a is not used.

[0122] Furthermore, in this embodiment, as described above, the medium-temperature water tank 4 is a tank that recovers and stores the medium-temperature water Htm after preheating and heat recovery that is stored in the sterilization tank 1. As a result, the medium-temperature water Htm to be preheated can be stored by recovering the medium-temperature water Htm after heat recovery, and the medium-temperature water Htm to be heat recovered can be stored by recovering the preheated medium-temperature water Htm. This allows the source of the medium-temperature water Htm to the sterilization tank 1 and the destination of the medium-temperature water Htm recovered from the sterilization tank 1 to be the single medium-temperature water tank 4, making it possible to realize a heat sterilization apparatus 100 that recovers heat and preheats with a simple configuration.

[0123] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0124] For example, in the above embodiment, the heat sterilization apparatus 100 is an example of a spray type apparatus equipped with the spray nozzle 2, but the present invention is not limited to this. In the present invention, the heat sterilization apparatus may be a hot water storage type apparatus that performs preheating and heat recovery using medium-temperature water, or a steam type apparatus that uses steam as a high-temperature fluid.

[0125] For example, the following heat sterilization control is performed in a hot water storage type heat sterilization apparatus 500 of a first modified example as shown in Fig. 23. That is, after heat sterilizing the retort pouch Rp (sterilization object) with high-temperature water Hth (high-temperature fluid) in the object heating step, the control unit 512 recovers the high-temperature water Hth (high-temperature fluid) discharged from the sterilization tank 1 into the high-temperature water tank 503, and then performs medium-temperature water heat recovery control to recover heat from the sterilization tank 1 after heat sterilization using medium-temperature water Htm generated separately from the high-temperature water Hth (high-temperature fluid).

[0126] Here, in the hot water storage type heat sterilization device 500, high temperature water Hth (high temperature fluid) is not used for heat sterilization, but after recovering the high temperature water Hth in the high temperature water tank 503, the medium temperature water Htm in the medium temperature water tank 4 is circulated to the sterilization tank 1, thereby enabling heat recovery from the sterilization tank 1 after heat sterilization, and therefore preventing the temperature of the high temperature water Hth from decreasing.

[0127] Furthermore, for example, in a steam-type heat sterilization apparatus 600 of a second modified example as shown in Fig. 24, the following heat sterilization control is performed. That is, after the control unit 612 heats and sterilizes the retort pouch Rp (sterilization object) with high-temperature steam Vah (high-temperature fluid) in the object heating step, it performs medium-temperature water heat recovery control to recover heat from the sterilization tank 1 after heat sterilization, using medium-temperature water Htm generated separately from the high-temperature steam Vah (high-temperature fluid).

[0128] Here, the steam-type heat sterilizer 600 uses steam Vah (high-temperature fluid) for heat sterilization instead of high-temperature water, so heat recovery using high-temperature water is not possible. However, with the above-described configuration of the second modified example of this embodiment, by performing medium-temperature water heat recovery control, the steam-type heat sterilizer 600 can also recover heat from the sterilization tank 1 after heat sterilization.

[0129] In addition, in the above embodiment, the heat sterilization apparatus 100 is provided with both the high-temperature water tank 3 and the medium-temperature water tank 4, but the present invention is not limited to this. In the present invention, the heat sterilization apparatus only needs to be provided with the medium-temperature water tank, and does not necessarily need to be provided with a hot water tank.

[0130] In the above embodiment, the heat sterilization apparatus 100 is an apparatus that heat sterilizes a retort pouch Rp containing food using high-temperature water Hth, but the present invention is not limited to this. In the present invention, the heat sterilization apparatus may also be an apparatus that heat sterilizes other products such as canned goods.

[0131] In the above embodiment, the control unit 12 is configured to directly use the medium-temperature water Htm supplied from the medium-temperature water tank 4 to preheat the sterilization tank 1 and the retort pouches Rp and to recover heat, but the present invention is not limited to this. That is, the heat sterilization device may have a modified configuration in which medium-temperature water is used indirectly, as described below.

[0132] Specifically, as in a third modified example shown in Fig. 25 , the heat sterilization apparatus 700 includes a heat transfer fluid supply unit 713 that supplies a heat transfer fluid Htf heated by medium-temperature water Htm. The heat sterilization apparatus 700 also includes a heat exchanger 714 that exchanges heat between the medium-temperature water Htm stored in the medium-temperature water tank 704 and the heat transfer fluid Htf supplied from the heat transfer fluid supply unit 713. In preheating the sterilization tank 1, the control unit 12 controls the supply of the heat transfer fluid Htf, the temperature of which has been increased by heat exchange with the medium-temperature water Htm in the heat exchanger 714, to the sterilization tank 1, and in heat recovery from the sterilization tank 1, the control unit 12 controls the supply of the heat transfer fluid Htf, the temperature of which has been decreased by heat exchange with the medium-temperature water Htm in the heat exchanger 714, to the sterilization tank 1.

[0133] As a result, compared to when the medium-temperature water Htm is directly supplied to the sterilization tank 1, by preheating the sterilization tank 1 by heating the heat transfer fluid Htf and the medium-temperature water Htm through heat exchange in the heat exchanger 714, the temperature of the heat transfer fluid Htf can be gradually increased while the heat transfer fluid Htf is supplied to the sterilization tank 1. Therefore, the temperature of the sterilization tank 1 can be gradually increased to the preheating temperature by the heat transfer fluid Htf while reducing the temperature difference with the sterilization tank 1. As a result, sudden temperature changes in the sterilization tank 1 can be further suppressed. Furthermore, by recovering heat by heat exchange between the heat transfer fluid Htf and the medium-temperature water Htm in the heat exchanger 714, the temperature of the heat transfer fluid Htf can be gradually reduced while the heat transfer fluid Htf is supplied to the sterilization tank 1. Therefore, by reducing the temperature difference with the sterilization tank 1, the sterilization tank 1 can be gradually lowered to the post-heat recovery temperature (pre-cooling temperature) by the heat transfer fluid Htf. As a result, sudden temperature changes in the sterilization tank 1 can be further suppressed.

[0134] 25, a medium-temperature water tank 704 is connected to a heat exchanger 714. That is, the medium-temperature water tank 704 includes an inlet pipe 704c, a supply pipe 704d, a flow path switching valve 704e, and a flow path switching valve 704f.

[0135] Furthermore, in the above embodiment, an example has been shown in which the control unit 12 performs both control to recover and store the medium-temperature water Htm in the sterilization tank 1 after preheating in the medium-temperature water tank 4, and control to recover and store the medium-temperature water Htm in the sterilization tank 1 after heat recovery in the medium-temperature water tank 4, but the present invention is not limited to this. In the present invention, it is sufficient that the control unit performs at least one of control to recover and store the medium-temperature water in the sterilization tank after preheating in the medium-temperature water tank, and control to recover and store the medium-temperature water in the sterilization tank after heat recovery in the medium-temperature water tank.

[0136] In the above embodiment, for convenience of explanation, the control processing of the control unit 12 is explained using a flow-driven flowchart in which processing is performed sequentially according to a processing flow, but the present invention is not limited to this. In the present invention, the control processing of the control unit may be performed by event-driven processing in which processing is performed on an event-by-event basis. In this case, the control processing may be performed completely event-driven, or may be performed in a combination of event-driven and flow-driven processing.

[0137] DESCRIPTION OF SYMBOLS 1 Sterilization tank 1d Storage space 3, 503 High temperature water tank 4, 704 Medium temperature water tank 5 Circulation path (first connection path, second connection path) 5a Discharge pipe line (first connection path, second connection path) 5b Discharge pipe line (first connection path, second connection path) 5c Upstream pipe line (first connection path, second connection path) 5d Downstream pipe line 5d (first connection path, second connection path) 5f Circulation pump 6a Common pipe line (first connection path, second connection path) 6b Branch pipe line (second connection path) 6c Branch pipe line (first connection path) 11 Heat exchanger 12, 612 Control unit 100, 500, 600, 700 Heat sterilization device 713 Heat transfer fluid supply unit 714 Heat exchanger Cw Cooling water Htf Heat transfer fluid Hth High temperature water Htm Medium temperature water Rp Retort pouch (object to be sterilized)

Claims

1. A heat sterilization device comprising: a sterilization tank having an accommodation space for accommodating objects to be heat sterilized with a high-temperature fluid, and to which the high-temperature fluid for heat sterilizing the objects and cooling water for cooling the objects heat sterilized with the high-temperature fluid are supplied; and a control unit for performing medium-temperature water heat recovery control for recovering heat from the sterilization tank after heat sterilization, using medium-temperature water that is generated separately from the high-temperature fluid and has a temperature higher than that of the cooling water but lower than that of the high-temperature fluid, before the objects are cooled by the cooling water.

2. The heat sterilization device as described in claim 1, wherein the control unit is configured to perform the medium temperature water heat recovery control when the high temperature fluid after heat sterilization has been discharged from the sterilization tank.

3. The heat sterilization device according to claim 1, further comprising a medium temperature water tank in which the medium temperature water is stored, and the control unit is configured to perform the medium temperature water heat recovery control, which recovers heat from the sterilization tank after heat sterilization, using the medium temperature water supplied from the medium temperature water tank before cooling of the object to be sterilized by the cooling water, and to store the medium temperature water used for the medium temperature water heat recovery control in the medium temperature water tank.

4. The heating sterilization device as described in claim 3, wherein the control unit is configured to perform preheating control to preheat the sterilization tank using the medium-temperature water heated during the medium-temperature water heat recovery control and stored in the medium-temperature water tank before heating of the object to be sterilized by the high-temperature fluid.

5. The heating sterilization device according to claim 4, further comprising a first connection path connecting the sterilization tank and the medium temperature water tank to each other, wherein the control unit is configured to control the recovery and storage of the medium temperature water in the sterilization tank after heat recovery in the medium temperature water tank via the first connection path, and to control the supply of the medium temperature water to the sterilization tank via the first connection path during preheating.

6. The heat sterilization device as described in claim 4, wherein the control unit is configured to control the release of the medium-temperature water supplied from the medium-temperature water tank toward the object to be sterilized during each of the preheating of the sterilization tank and the heat recovery of the sterilization tank.

7. The heating sterilization device according to claim 1, further comprising: a high-temperature water tank for recovering and storing the high-temperature water, which is the high-temperature fluid after heating and sterilization stored in the sterilization tank; and a second connection path connecting the sterilization tank and the high-temperature water tank to each other, wherein the control unit is configured to perform the medium-temperature water heat recovery control of the sterilization tank after the heating and sterilization of the object to be sterilized is completed and then recover the high-temperature water discharged from the sterilization tank into the high-temperature water tank via the second connection path.

8. A heating sterilization apparatus as described in claim 3, further comprising: a heat transfer fluid supply unit which supplies a heat transfer fluid heated by the medium temperature water; and a heat exchanger which performs heat exchange between the medium temperature water stored in the medium temperature water tank and the heat transfer fluid supplied from the heat transfer fluid supply unit, wherein the control unit is configured to control the supply of the heat transfer fluid, the temperature of which has been increased by heat exchange with the medium temperature water in the heat exchanger, to the sterilization tank in preheating of the sterilization tank, and to control the supply of the heat transfer fluid, the temperature of which has been decreased by heat exchange with the medium temperature water in the heat exchanger, to the sterilization tank in heat recovery of the sterilization tank.

9. The heating and sterilizing device of claim 1, further comprising a circulation path including a circulation pump that discharges each of the cooling water, the high-temperature fluid and the medium-temperature water discharged from the sterilization tank and circulates them back to the sterilization tank, and the control unit is configured to perform the medium-temperature water heat recovery control by circulating the medium-temperature water to the sterilization tank via the circulation path using the circulation pump.

10. An object to be sterilized that has been heat sterilized by a heat sterilization device having a storage space inside for storing the object to be heat sterilized with a high-temperature fluid, a sterilization tank to which the high-temperature fluid for heat sterilizing the object and cooling water for cooling the object to be sterilized by the high-temperature fluid are supplied, and a control unit that performs medium-temperature water heat recovery control to recover heat from the sterilization tank after heat sterilization using medium-temperature water that is generated separately from the high-temperature fluid and has a temperature higher than that of the cooling water but lower than that of the high-temperature fluid before the object to be sterilized is cooled by the cooling water.

11. A method for heat sterilization comprising the steps of: supplying a high-temperature fluid to a sterilization tank in which heat sterilization is performed with the high-temperature fluid, and heat sterilizing an object to be sterilized in the sterilization tank; recovering heat from the sterilization tank after heat sterilization using medium-temperature water that is higher in temperature than the cooling water but lower in temperature than the high-temperature fluid and that is generated separately from the high-temperature fluid, before cooling the object to be sterilized with cooling water; and cooling the object to be sterilized that has been heat sterilized with the cooling water after heat recovery from the sterilization tank.

12. The heating and sterilization method according to claim 11, further comprising a step of preheating the sterilization tank using the medium-temperature water heated during the heat recovery from the sterilization tank before the high-temperature fluid for heating and sterilizing the object to be sterilized is supplied to the sterilization tank.

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