JP2010181042A - Cooling device and cooling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a cooling time while preventing the bump of a cooled object and to reduce the usage of water and steam used in a pressure reducing means in a processing tank, in a vacuum cooling process. <P>SOLUTION: In vacuum cooling the cooled object received in the processing tank, a rapid cooling process for reducing pressure in the processing tank to set pressure P1, and a slow cooling process for further reducing the pressure in the processing tank while lowering a pressure reducing capacity in comparison with that in the rapid cooling process are successively executed. The set pressure P1 is determined to be pressure higher than initial temperature reduced pressure P2 in which a saturated steam temperature in the processing tank becomes equal to a temperature of the cooled object by allowance pressure 3, and the allowance pressure P3 is determined so that the lower the initial temperature reduced pressure P2 is the smaller the allowance pressure is. For example, the set pressure P1 is set to the pressure of a set ratio of the initial temperature reduced pressure P2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a vacuum cooling function such as a vacuum cooling device (vacuum cooling dedicated machine) that vacuum-cools an object to be cooled such as food and foodstuffs, as well as a composite cooling device that can perform vacuum cooling and cold air cooling of the object to be cooled. And a cooling method using such a cooling device.

  Vacuum cooling is known as a method for cooling food and food materials (hereinafter simply referred to as food). Vacuum cooling is a method that promotes the evaporation of moisture from food by sucking and discharging the gas in the processing tank containing food to the outside and decompressing the inside of the processing tank, and cooling the food by the heat of vaporization. It is.

  During vacuum cooling, as the inside of the treatment tank is depressurized, the saturated vapor temperature in the treatment tank decreases. At that time, when the saturated vapor temperature in the treatment tank is significantly lower than the temperature of the food, the food may bump, and the appearance, flavor, and yield of the food may be deteriorated. Therefore, it is necessary to reduce the pressure while keeping the saturated steam temperature in the treatment tank and the temperature of the food within a desired temperature difference, and this requires adjustment of the decompression capacity.

  However, if the pressure reduction capability is limited from the beginning of cooling, it takes a long cooling time. Therefore, as disclosed in Patent Document 1 below, the food is rapidly cooled by increasing the decompression capacity until the saturated steam temperature in the treatment tank becomes equal to the temperature of the food or the difference between the two temperatures reaches a set value. A cooling apparatus has been proposed that performs slow cooling of food by reducing the pressure reduction capacity after the set value. In other words, until the difference between the saturated steam temperature in the treatment tank and the temperature of the food disappears or reaches the set value, the food is rapidly cooled by increasing the decompression capacity, and then the food is gradually cooled by decreasing the decompression capacity. A cooling device has been proposed.

JP 2008-157488 A

  However, reducing the pressure in the processing tank until the saturated steam temperature in the processing tank becomes the same as the temperature of the food, the pressure in the processing tank is equivalent to the product temperature equivalent pressure of the food (the saturated steam temperature in the processing tank is There is a risk that the pressure will be much lower than the pressure that is equal to the temperature of the above-mentioned temperature. Therefore, in the cooling of foods where cooling quality deterioration due to bumping is a problem, the pressure reduction capacity in the treatment tank is increased until the difference between the saturated steam temperature in the treatment tank and the food temperature reaches a set value. Will do.

  Specifically, after reducing the pressure in the treatment tank until the set pressure is higher than the product temperature conversion pressure by a margin pressure, the pressure inside the treatment tank is further reduced by lowering the pressure reduction capacity. In this case, the margin pressure is set in consideration of the time from the start of changing the pressure reduction speed at the set pressure to when the pressure reduction speed actually decreases as desired. However, if the surplus pressure is unchanged regardless of the level of the product temperature conversion pressure, the surplus pressure is too small, the pressure in the treatment tank is much lower than the product temperature conversion pressure, or conversely, the surplus pressure is too large, There is a disadvantage that the cooling time is unnecessarily long. This point will be specifically described below.

  FIG. 3 is a diagram showing the relationship between the elapsed time from the start of depressurization in the treatment tank and the pressure in the treatment tank, and the solid line is the inside of the treatment tank when the temperature of the food at the start of vacuum cooling is 50 ° C. The pressure change and the broken line show the pressure change in the treatment tank when the temperature of the food at the start of vacuum cooling is 10 ° C.

  First, the case where the food temperature at the start of vacuum cooling is 50 ° C. will be described. In this case, the product temperature converted pressure PA is defined as a saturated steam pressure at which the saturated steam temperature is 50 ° C., and is 123 hPa. The margin pressure PB is set to 50 hPa, for example. As a result, the set pressure PC is set to 173 hPa as a value obtained by adding the margin pressure PB (= 50 hPa) to the product temperature converted pressure PA (= 123 hPa). Therefore, after reducing the pressure in the processing tank until the set pressure reaches 173 hPa, the pressure in the processing tank is further reduced while adjusting the pressure reducing capacity. This realizes rapid vacuum cooling while preventing food boiling.

  However, when 50 hPa is set as the marginal pressure PB as described above, even if rapid vacuum cooling is achieved while preventing food bumping, the food temperature at the start of vacuum cooling is 50 ° C. Limited. Therefore, the lower the temperature of the food at the start of vacuum cooling is below 50 ° C., the more waste the cooling time. For example, assume that the temperature of the food at the start of vacuum cooling is 10 ° C. In this case, the product temperature converted pressure PA ′ is defined as a saturated steam pressure at which the saturated steam temperature becomes 10 ° C., and is 12.3 hPa. In this case as well, when 50 hPa is used as the margin pressure PB as in the case where the food temperature is 50 ° C., the set pressure PC ′ is set to the product temperature equivalent pressure PA ′ (= 12.3 hPa) and the margin pressure PB (= 50 hPa). ) Is set to 62.3 hPa, which corresponds to 37 ° C. when converted to a saturated steam temperature. In other words, the pressure reduction speed is adjusted from a pressure much higher than the product temperature equivalent pressure, and the cooling time becomes longer.

  Thus, since the temperature of the food at the start of vacuum cooling is not always constant, if the surplus pressure remains unchanged regardless of the level of the product temperature conversion pressure, the temperature of the food at the start of vacuum cooling decreases. The cooling time is wasted. Moreover, in order to achieve vacuum cooling down to 10 ° C., for example, a steam ejector, an indirect heat exchanger for steam condensation, and a water ring vacuum pump are usually used as decompression means in the treatment tank. If it becomes long, the amount of steam used for the sealing water used for a vacuum pump, the cooling water used for an indirect heat exchanger, and a steam ejector will each increase.

  The problem to be solved by the present invention is to shorten the cooling time while preventing bumping of the object to be cooled, and to reduce the amount of water and steam used for the decompression means in the treatment tank.

  The present invention has been made to solve the above problems, and the invention according to claim 1 is a treatment tank in which an object to be cooled is accommodated, and a gas in the treatment tank is sucked and discharged to the outside. Depressurization means for depressurizing the inside of the treatment tank, a return pressure means for introducing outside air into the decompressed treatment tank to restore the pressure in the treatment tank, and a pressure sensor for detecting the pressure in the treatment tank. Provided, it is possible to sequentially execute a rapid cooling step of reducing the inside of the treatment tank to a set pressure, and a slow cooling step of lowering the pressure inside the treatment tank by lowering the decompression capacity than the rapid cooling step, and the set pressure is The saturated steam temperature in the treatment tank is set to a pressure that is higher by a margin pressure than the product temperature conversion pressure at which the temperature of the object to be cooled becomes equal, and the margin pressure decreases as the product temperature conversion pressure decreases. It is a cooling device characterized by being set to become

  According to the invention described in claim 1, after reducing the pressure in the treatment tank until the set pressure is higher than the product temperature conversion pressure by a margin pressure, when the pressure is further reduced by reducing the decompression capacity, It is set so as to decrease as the temperature-converted pressure decreases. Thereby, for example, when it is possible to predict whether the temperature of the object to be cooled accommodated in the treatment tank is known in advance, the product temperature at which the saturated vapor temperature in the treatment tank becomes equal to the temperature of the object to be cooled (referred to as the product temperature) By reducing the pressure reducing capacity after reducing the pressure in the treatment tank to a set pressure that is higher than the surplus pressure by using the converted pressure, the cooling time can be shortened while preventing bumping of the object to be cooled. Then, by reducing the cooling time, it is possible to reduce the amount of water and steam used for the decompression means in the treatment tank. Moreover, since it can cool by designating a target pressure, it is possible to handle an object to be cooled on which a product temperature sensor cannot be inserted.

  Invention of Claim 2 is further equipped with the product temperature sensor which detects the temperature of the to-be-cooled object accommodated in the said processing tank, and the said product temperature conversion pressure is the said rapid cooling process in the start or during the said rapid cooling process 2. The cooling device according to claim 1, wherein the cooling device is calculated based on a temperature detected by the product temperature sensor, and the margin pressure is set to decrease as the product temperature conversion pressure decreases.

  According to the invention described in claim 2, by using the product temperature sensor, the cooling time can be shortened more reliably while preventing the object to be cooled from bumping, and the water and steam used for the decompression means in the treatment tank can be reduced. The amount of usage can be reduced.

  According to a third aspect of the present invention, the set pressure is set to a pressure at a set ratio of the product temperature converted pressure calculated based on a temperature detected by the product temperature sensor at the start of the rapid cooling process or during the rapid cooling process. The cooling device according to claim 2.

  According to the third aspect of the present invention, the set pressure is set to a pressure corresponding to the set ratio of the product temperature converted pressure, and the margin pressure is easily changed so as to decrease as the product temperature converted pressure decreases. Will be.

  According to a fourth aspect of the present invention, the set pressure is equal to a temperature at which a saturated steam temperature in the processing tank is added to a temperature detected by the product temperature sensor at the start of the rapid cooling process or during the rapid cooling process. The cooling device according to claim 2, wherein the pressure is set to

  According to the fourth aspect of the present invention, the set pressure is set to a pressure at which the saturated steam temperature in the treatment tank is equal to the temperature obtained by adding a predetermined temperature to the product temperature, and the margin pressure is converted to the product temperature. The pressure is easily changed so as to decrease as the pressure decreases.

  In the invention according to claim 5, the margin pressure is set so as to decrease as the product temperature conversion pressure decreases, or is set to a constant value regardless of the product temperature conversion pressure. When the pressure in the processing tank reaches a pressure obtained by adding a predetermined pressure to the set pressure, a pressure reduction speed at that time is calculated, and the pressure reduction capacity is reduced from the pressure reduction speed at the calculated pressure reduction speed. The pressure reducing capability is lowered before reaching the set pressure when it is determined that the pressure in the processing tank is lower than the product temperature equivalent pressure. It is a cooling device as described in above.

  According to the invention described in claim 5, before the inside of the processing tank reaches the set pressure, the decompression speed at that time is calculated, and the decompression capacity can be adjusted based on the result, thereby more reliably. The cooling time can be shortened while preventing the object to be cooled from bumping.

  Furthermore, the invention according to claim 6 is a method for cooling an object to be cooled accommodated in a processing tank, wherein a rapid cooling step for reducing the pressure in the processing tank to a set pressure, and a pressure reducing capacity than the rapid cooling step. In order to further reduce the pressure in the treatment tank, and the set pressure is more than a product temperature equivalent pressure at which the saturated steam temperature in the treatment tank becomes equal to the temperature of the object to be cooled. The cooling method is characterized in that the pressure is set to a higher pressure, and the margin pressure is set to be smaller as the product temperature conversion pressure is lower.

  According to the invention described in claim 6, after reducing the pressure in the treatment tank until the set pressure is higher than the product temperature conversion pressure by a margin pressure, when the pressure is further reduced by reducing the decompression capacity, It is set so as to decrease as the temperature-converted pressure decreases. Thereby, for example, when it is possible to predict whether the temperature of the object to be cooled accommodated in the treatment tank is known in advance, the product temperature at which the saturated vapor temperature in the treatment tank becomes equal to the temperature of the object to be cooled (referred to as the product temperature) By reducing the pressure reducing capacity after reducing the pressure in the treatment tank to a set pressure that is higher than the surplus pressure by using the converted pressure, the cooling time can be shortened while preventing bumping of the object to be cooled. Then, by reducing the cooling time, it is possible to reduce the amount of water and steam used for the decompression means in the treatment tank. Moreover, since it can cool by designating a target pressure, it is possible to handle an object to be cooled on which a product temperature sensor cannot be inserted.

  According to the present invention, after reducing the pressure in the treatment tank until the set pressure is higher than the product temperature converted pressure by a margin pressure, the margin pressure is lower than the product temperature converted pressure. It is set so as to become smaller. Thereby, for example, the cooling time can be shortened while preventing the object to be cooled from bumping. Then, by reducing the cooling time, it is possible to reduce the amount of water and steam used for the decompression means in the treatment tank.

It is a schematic block diagram which shows one Example of the cooling device of this invention, and has shown the example applied to the vacuum cooling device. It is a figure which shows an example of the cooling method using the cooling device of FIG. 1, and has shown the relationship between the elapsed time from the pressure reduction start in a processing tank, and the pressure in a processing tank. It is a figure which shows the conventional cooling method, and has shown the relationship between the elapsed time from the pressure reduction start in a processing tank, and the pressure in a processing tank.

Next, an embodiment of the present invention will be described.
The present invention is applied to various cooling devices having a vacuum cooling function. The object to be cooled by the cooling device is not particularly limited, but is typically food. Therefore, in the following description, it is assumed that the object to be cooled is food.

  Vacuum cooling is the process of sucking and discharging the gas in the processing tank to the outside and reducing the pressure in the processing tank, thereby lowering the saturated vapor temperature in the processing tank and promoting the evaporation of moisture from food. It means cooling the food in the processing tank using latent heat.

  Devices having a vacuum cooling function include, for example, a vacuum cooling device, a steaming cooling device, a saturated steam cooking device, and a cold air vacuum combined cooling device. The vacuum cooling device is a device that depressurizes the inside of the processing tank and vacuum-cools the food in the processing tank. The steaming and cooling device is a device for vacuuming the food in the processing tank by heating the food in the processing tank with steam and then reducing the pressure in the processing tank. The saturated steam cooking device is a device that adjusts the saturated steam temperature in the processing tank by adjusting the pressure in the processing tank, and heats the food in the processing tank with saturated steam at a desired temperature. The apparatus is capable of reducing the pressure in the processing tank and cooling the food in the processing tank if desired. Furthermore, the cold air vacuum combined cooling device is a device capable of achieving cold air cooling by blowing cold air to food in the processing tank and vacuum cooling by reducing the pressure in the processing tank containing the food.

  In any case of the vacuum cooling device, the steaming cooling device, the saturated steam cooking device, the cold air vacuum combined cooling device, etc., the configuration and operation relating to the vacuum cooling function are the same. Therefore, in the following embodiments, a vacuum cooling device having only a vacuum cooling function will be described, but the present invention can be similarly applied to a steaming cooling device, a saturated steam cooking device, a cold air vacuum combined cooling device, and the like.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a use state of an embodiment of a cooling device of the present invention, and a part thereof is shown in cross section. The cooling device of the present embodiment is a vacuum cooling device.

  The cooling device 1 includes a processing tank 3 in which a food 2 to be cooled is accommodated, a decompression means 4 that sucks and discharges the gas in the processing tank 3 to the outside and decompresses the processing tank 3, and the pressure is reduced. Pressure return means 5 for introducing outside air into the treatment tank 3 to restore the pressure in the treatment tank 3, a pressure sensor 6 for detecting the pressure in the treatment tank 3, and the temperature of the food 2 stored in the treatment tank 3 ( A product temperature sensor 7 for detecting the product temperature) and a control means 8 for controlling the means 4 and 5 based on detection signals of the sensors 6 and 7.

  The processing tank 3 of the present embodiment is a metal can body including a processing tank main body 9 that opens to the front and has a hollow portion, and a door (not shown) that opens and closes the opening of the processing tank main body 9. is there. The food 2 may be accommodated in the processing tank 3 via a wagon (not shown) that is taken in and out of the processing tank 3, or by providing a shelf board 10 in the processing tank 3 as shown in the example. May correspond. In addition, the food 2 is appropriately placed in a container 11 such as a hotel bread and stored in the processing tank 3. After accommodating the food 2 in the processing tank 3, the hollow part of the processing tank main body 9 is sealed by closing the door.

  The processing tank 3 is provided with the pressure sensor 6 and the product temperature sensor 7 as described above. The product temperature sensor 7 of the present embodiment detects the temperature of the food 2 by inserting the temperature measuring unit into the food 2.

  The processing tank 3 is connected to a decompression means 4 that sucks and discharges air and steam in the processing tank 3 to the outside and decompresses the processing tank 3. In this embodiment, a steam ejector 13, a heat exchanger 14, a check valve 15, and a water-sealed vacuum pump 16 are provided in the exhaust path 12 from the processing tank 3 in order from the processing tank 3 side.

  The steam ejector 13 has a suction port 17 connected to the processing tank 3 via a vacuum valve 18. The steam ejector 13 can eject steam from the steam supply path 21 from the inlet 19 toward the outlet 20. In the state where the vacuum valve 18 is opened, the vapor in the processing tank 3 is sucked and discharged toward the outlet by ejecting steam from the inlet 19 toward the outlet 20. By operating opening / closing of the steam supply valve 22 provided in the steam supply path 21, it is possible to switch the operation of the steam ejector 13.

  The heat exchanger 14 cools and condenses the steam in the exhaust passage 12. Therefore, water is supplied to the heat exchanger 14 via the heat exchange water supply valve 23 and discharged. By condensing the vapor in the exhaust passage 12 in advance, the subsequent load on the vacuum pump 16 can be reduced, and the pressure reduction in the processing tank 3 can be effectively achieved.

  As is well known, the water-sealed vacuum pump 16 is supplied with water called sealed water. Therefore, water is supplied to the vacuum pump 16 through the sealed water supply valve 24 and discharged. When the vacuum pump 16 is operated, the sealed water supply valve 24 is opened in conjunction with the vacuum pump 16.

  The treatment tank 3 is connected to a decompression means 5 for introducing outside air into the decompressed treatment tank 3 and restoring the pressure in the treatment tank 3. In the present embodiment, a sterilization filter 26, an air supply valve 27, and a check valve 28 are sequentially provided in the air supply path 25 to the processing tank 3 toward the processing tank 3. Therefore, when the air supply valve 27 is opened while the inside of the processing tank 3 is decompressed, the outside air can be introduced into the processing tank 3 through the filter 26 and the inside of the processing tank 3 can be decompressed.

  The air supply valve 27 may be an electromagnetic valve that can only be opened and closed, but is preferably an electric valve that can be adjusted in opening. In this case, the pressure in the processing tank 3 can be gradually changed by adjusting the opening of the air supply valve 27 at the time of depressurization or return pressure in the processing tank 3.

  The decompression means 4 and the decompression means 5 are controlled by the control means 8. The control means 8 is a controller 29 that controls the means 4 and 5 based on the detection signals of the sensors 6 and 7. Specifically, the vacuum valve 18, the steam supply valve 22, the heat exchange water supply valve 23, the vacuum pump 16, the sealed water supply water valve 24, the air supply valve 27, the pressure sensor 6, and the product temperature sensor 7 are connected to the controller 29. Has been. And the controller 29 aims at the vacuum cooling of the foodstuff 2 in the processing tank 3 according to a predetermined | prescribed procedure (program) as described below.

  Hereinafter, the cooling method using the cooling device 1 of the present embodiment will be specifically described. The cooling method of the present embodiment is a vacuum in which a rapid cooling step for reducing the pressure inside the processing tank 3 to a set pressure and a slow cooling step for lowering the pressure inside the processing tank 3 by lowering the pressure reduction capacity than the rapid cooling step are performed in order. It is a cooling method. Prior to such a series of vacuum cooling, the processing tank 3 contains the food 2 to be cooled, and the door of the processing tank 3 is closed. The food 2 accommodated in the processing tank 3 may be cooled to some extent by another cooling device (blast chiller or differential pressure cooling device) as desired.

  In order to depressurize the inside of the processing tank 3 from the atmospheric pressure for the rapid cooling process, the vacuum pump 16 may be operated while the air supply valve 27 is closed and the vacuum valve 18 and the sealed water supply valve 24 are open. . Usually, at the initial stage of the rapid cooling process, the heat exchange water supply valve 23 is closed and water does not flow into the heat exchanger 14, and a fixed time elapses or the outlet temperature of the heat exchanger 14 (the exhaust path 12 from the treatment tank 3 is discharged). When the temperature in the pipe from the heat exchanger 14 to the vacuum pump 16 exceeds a predetermined temperature, the heat exchange water supply valve 23 is opened to allow water to flow through the heat exchanger 14. When the outlet temperature of the heat exchanger 14 further rises to a predetermined level, water cooled in advance by a chiller (not shown) is preferably flowed as cooling water to the heat exchanger 14. Further, at the initial stage of the rapid cooling process, the steam supply valve 22 is closed and the steam ejector 13 is not operated, and the pressure that the vacuum pump 16 is insufficient to further depressurize the inside of the processing tank 3 as the processing tank 3 is depressurized. When it becomes less than (for example, 45 hPa), the steam supply valve 22 is opened and the steam ejector 13 is also operated.

  In the subsequent slow cooling step, the pressure reducing capability is made lower than that in the rapid cooling step, and further pressure reduction in the treatment tank 3 is achieved. For this purpose, for example, the inside of the treatment tank 3 may be decompressed by the decompression means 4 while opening the air supply valve 27 closed in the rapid cooling process as appropriate. Specifically, if the air supply valve 27 is an electromagnetic valve, the processing tank 3 may be opened and closed as desired, and if the air supply valve 27 is an electric valve, the inside of the processing tank 3 is reduced as desired. It is sufficient to adjust the opening degree. In either case, the relationship between the elapsed time and the target pressure in the processing tank 3 is set in advance, and the pressure in the processing tank 3 is reduced while adjusting the pressure reduction speed along the relationship.

  However, the adjustment of the pressure reduction rate in the slow cooling step is not limited to this and can be changed as appropriate. For example, a plurality of air supply paths 25 into the processing tank 3 are provided in parallel, and an air supply valve 27 is provided in each of the air supply paths 25, and the plurality of air supply valves 27 thus provided are provided. Of these, the number of openings may be changed for control. Alternatively, an outside air introduction path (not shown) may be connected in the middle of the exhaust path 12, and the opening / closing and opening degree of an outside air introduction valve (not shown) provided in the outside air introduction path may be adjusted. Furthermore, the opening degree of the vacuum valve 18 may be adjusted, or the rotational speed of the vacuum pump 16 may be changed using an inverter. These may combine a plurality of methods. In any case, normally, in the rapid cooling process, the supply valve 27, the outside air introduction valve, and the like are closed, the inside of the processing tank 3 is decompressed without restricting the decompression capacity, and the decompression capacity is adjusted in the subsequent slow cooling process. It will be.

  As shown in FIG. 2, in the rapid cooling process, the inside of the processing tank 3 is reduced to the set pressure P <b> 1, and the set pressure P <b> 1 is the product temperature at which the saturated steam temperature in the processing tank 3 becomes equal to the detected temperature of the product temperature sensor 7. The pressure is set higher than the conversion pressure P2 by a margin pressure P3. That is, when the inside of the processing tank 3 is depressurized, the saturated steam temperature in the processing tank 3 decreases accordingly, but if the saturated steam temperature in the processing tank 3 is significantly lower than the product temperature, the food 2 may cause bumping. Therefore, a pressure that is higher by the margin pressure P3 than the product temperature conversion pressure P2 at which the saturated steam temperature in the processing tank 3 becomes equal to the product temperature is set as the set pressure P1.

  In the rapid cooling step, the food 2 in the processing tank 3 is vacuum-cooled with the reduced pressure in the processing tank 3, so that the product temperature decreases. Therefore, the product temperature for obtaining the product temperature converted pressure P2 and the set pressure P1 may be a product temperature that decreases every moment during the rapid cooling process, or may be an initial product temperature at the start of the rapid cooling process.

  And in this invention, the said margin pressure P3 is set so that it may become so small that the product temperature conversion pressure P2 becomes low. The higher the product temperature converted pressure P2, the higher the pressure reduction speed. Therefore, it is necessary to prepare for shifting to the slow cooling process by increasing the margin pressure P3, but the lower the product temperature converted pressure P2, the lower the pressure reduction speed. This is because the marginal pressure P3 may be reduced, otherwise the cooling time is wasted. In addition, the longer the cooling time, the more the sealed water used for the vacuum pump 16, the cooling water used for the heat exchanger 14, and the amount of steam used for the steam ejector 13. However, if the margin pressure P3 is made too small, the pressure reduction rate at the set pressure P1 will not fall in time, and the risk that the pressure in the processing tank will exceed the product temperature equivalent pressure P2 will increase. In view of this, the margin pressure P3 and the set pressure P1 are determined.

  If the margin pressure P3 becomes smaller as the product temperature converted pressure P2 becomes lower, the setting method of the set pressure P1 is not particularly limited, but in this embodiment, the pressure of the set ratio of the product temperature converted pressure P2 is set as the set pressure. The In consideration of the above circumstances, for example, 110 to 150%, preferably 110 to 130% is used as the setting ratio. The setting ratio may be a fixed value, but it is preferable that the setting ratio can be set variably.

  The lower limit value of the setting ratio is 110% and the upper limit value is 150% (preferably 130%). When the product temperature conversion pressure P2 is 35 hPa, for example, when the product temperature conversion pressure P2 is 35 hPa, 36.75 hPa, the marginal pressure P3 becomes as small as 1.75 hPa, and if the adjustment to slow down the pressure reduction time is in time, it can be brought close to the product temperature equivalent pressure P2, but the steam ejector 13 is operating. This is because, in the degree of decompression, since a rapid decompression occurs, the desired decompression speed cannot be adjusted while the surplus pressure of 1.75 hPa is reduced. Further, when the upper limit value is exceeded (for example, 155%), when the product temperature converted pressure P2 is 35 hPa, for example, the set pressure P1 becomes 54.25 hPa and the marginal pressure P3 increases to 19.25 hPa, resulting in wasted cooling time. Because.

  In the present embodiment, the set ratio is, for example, 120%. That is, 120% of the product temperature converted pressure P2 is set as the set pressure P1. Thus, by setting the set ratio of the product temperature converted pressure P2 to the set pressure P1, the margin pressure P3 is set to automatically decrease as the product temperature converted pressure P2 decreases.

  FIG. 2 is a diagram showing an example of a cooling method using the cooling device 1 of the present embodiment, and shows a relationship between an elapsed time from the start of pressure reduction in the processing tank 3 and a pressure in the processing tank 3. In this figure, the solid line indicates the case where the temperature of the food 2 at the start of cooling is 50 ° C., and the broken line indicates the case where the temperature of the food 2 at the start of cooling is 10 ° C.

  First, the case where the product temperature at the start of cooling is 50 ° C. will be described. In this case, the product temperature converted pressure P2 is defined as a saturated steam pressure at which the saturated steam temperature is 50 ° C., and is 123 hPa. The set pressure P1 is 148 hPa as a value of 120% of this 123 hPa. Accordingly, after the pressure in the processing tank 3 is reduced until the pressure in the processing tank 3 reaches the set pressure P1 (= 148 hPa), the pressure in the processing tank 3 is further reduced while adjusting the pressure reducing capacity. The margin pressure P3 in this case is 25 hPa as a value obtained by subtracting the product temperature converted pressure P2 (= 123 hPa) from the set pressure P1 (= 148 hPa).

  Next, the case where the product temperature at the start of cooling is 10 ° C. will be described. Note that the set pressure P1, the product temperature conversion pressure P2, and the margin pressure P3 are distinguished from the case where the initial product temperature is 50 ° C. by adding a dash when the initial product temperature is 10 ° C., and P1 ′, It may be written as P2 ′ and P3 ′. When the initial product temperature is 10 ° C., the product temperature converted pressure P2 ′ is defined as the saturated steam pressure at which the saturated steam temperature is 10 ° C., and is 12.3 hPa. The set pressure P1 ′ is 14.8 hPa as a value of 120% of this 12.3 hPa. Therefore, after the pressure in the processing tank 3 is reduced until the pressure in the processing tank 3 reaches the set pressure P1 ′ (= 14.8 hPa), the pressure in the processing tank 3 is further reduced while adjusting the pressure reduction capacity. The margin pressure P3 ′ in this case is 2.5 hPa as a value obtained by subtracting the product temperature converted pressure P2 ′ (= 12.3 hPa) from the set pressure P1 ′ (= 14.8 hPa).

  When comparing the case where the initial product temperature is 50 ° C. with the case of 10 ° C., as described above, the former margin pressure P3 is 25 hPa, while the latter margin pressure P3 ′ is 2.5 hPa. Thus, in this embodiment, the margin pressure P3 is set smaller as the product temperature equivalent pressure P2 becomes lower. Therefore, it is possible to shorten the cooling time while preventing bumping of the food 2 by a simple method, and to reduce the amount of water and steam used for the decompression means 4 in the treatment tank 3.

  As described above, the setting method of the set pressure P1 is not particularly limited as long as the margin pressure P3 is set to be smaller as the product temperature converted pressure P2 is lower. Therefore, the set pressure P1 can be set as follows in addition to the pressure at the set ratio of the product temperature converted pressure P2. That is, the set pressure P1 may be set to a pressure at which the saturated steam temperature in the processing tank 3 becomes equal to a temperature obtained by adding a predetermined temperature to the temperature detected by the product temperature sensor 7 at the start of the rapid cooling process or during the rapid cooling process. This predetermined temperature is determined in the same manner as in the case of the set ratio in the above embodiment, and is set in the range of 2 to 5 ° C., for example.

  Specifically, the predetermined temperature is set to 3 ° C., for example. In this case, if the product temperature at the start of cooling is 50 ° C., the set pressure P1 is a temperature (53 ° C.) obtained by adding the predetermined temperature (3 ° C.) to the product temperature (50 ° C.). ) And is defined as a saturated vapor pressure of 143 hPa. Therefore, after reducing the pressure inside the processing tank 3 until the inside of the processing tank 3 reaches the set pressure P1 (= 143 hPa), the inside of the processing tank 3 is further reduced while adjusting the pressure reducing capacity. The margin pressure P3 in this case is 20 hPa as a value obtained by subtracting the product temperature converted pressure P2 (= 123 hPa) from the set pressure P1 (= 143 hPa).

  When the product temperature at the start of cooling is 10 ° C., the set pressure P1 is a temperature (13 ° C.) obtained by adding a predetermined temperature (3 ° C.) to the product temperature (10 ° C.) as the saturated steam temperature in the treatment tank 3. It is defined as a saturated vapor pressure that becomes 15 hPa. Therefore, after reducing the pressure inside the processing tank 3 until the inside of the processing tank 3 reaches the set pressure P1 (= 15 hPa), the inside of the processing tank 3 is further reduced while adjusting the pressure reducing capacity. The margin pressure P3 in this case is 2.7 hPa as a value obtained by subtracting the product temperature converted pressure P2 (= 12.3 hPa) from the set pressure P1 (= 15 hPa).

  Further, instead of or in addition to the configuration of the above embodiment, the following control may be performed. That is, in the rapid cooling process, when the pressure in the treatment tank 3 reaches a pressure obtained by adding a predetermined pressure P4 (for example, several hPa) to the set pressure P1, the decompression speed at that time is calculated, and the calculated decompression speed remains as it is. When the pressure is reduced to the set pressure P1 and the pressure reducing capacity is lowered from that, the pressure in the processing tank 3 is lower than the product temperature equivalent pressure P2 (including the case where the pressure falls below a predetermined value). The pressure reducing capacity may be lowered before reaching the set pressure. In this case, the margin pressure P3 and / or the predetermined pressure P4 may be set to decrease as the product temperature converted pressure P2 decreases, or may be set to a constant value regardless of the product temperature converted pressure P2. Good.

  The cooling device and the cooling method of the present invention are not limited to the configuration of the above embodiment, and can be changed as appropriate. In particular, it includes a rapid cooling process in which the inside of the processing tank 3 is reduced to the set pressure P1, and a slow cooling process in which the pressure reducing capacity is made lower than that in the rapid cooling process to further reduce the pressure in the processing tank 3. If the margin pressure P3 is set higher than the temperature conversion pressure P2 by a margin pressure P3, and the margin pressure P3 is set to decrease as the product temperature conversion pressure P2 decreases, other configurations and controls can be changed as appropriate. is there. Therefore, the product temperature converted pressure P2 is not necessarily calculated based on the temperature detected by the product temperature sensor 7. For example, when the product temperature of the food 2 stored in the treatment tank 3 can be predicted in advance, a pressure at which the saturated steam temperature in the treatment tank 3 becomes equal to the product temperature is set as the product temperature conversion pressure P2. By doing so, the cooling time can be shortened while preventing the food 2 from bumping. In this case, the food 2 to which the product temperature sensor 7 cannot be inserted can also be handled.

  Moreover, in the said Example, although the example applied to the vacuum cooling device was shown, it is applicable similarly to a steaming cooling device, a saturated steam cooking device, a cold air vacuum compound cooling device, etc. That is, in the case of a steaming cooling device or a saturated steam cooking device, a steam supply means for supplying steam into the treatment tank 3 may be further installed in the above embodiment. Thereby, after steam is supplied into the processing tank 3 by the steam supply means and the food 2 is heated, the pressure in the processing tank 3 can be reduced by the decompression means 4 to achieve vacuum cooling of the food 2. . However, the steam supply means may evaporate the water previously stored in the processing tank 3 with a heater in addition to supplying steam from a boiler or the like into the processing tank 3. In the case of the cold air vacuum combined cooling device, means (cooler and fan) for generating cold air in the processing tank 3 may be further installed in the above embodiment. Thereby, the vacuum cooling by decompressing the inside of the processing tank 3 containing the food 2 and the cold air cooling by blowing cold air to the food 2 in the processing tank 3 can be achieved.

  Furthermore, each structure of the decompression means 4 and the decompression means 5 is not limited to the structure of the said Example. For example, the decompression means 4 may omit the steam ejector 13 in the above embodiment, or may use a water ejector instead of the heat exchanger 14 or the vacuum pump 16. Further, as the return pressure means 5, a plurality of air supply paths 25 may be provided in parallel, and an electromagnetic valve may be provided for each.

1 Cooling device (vacuum cooling device)
2 Food (cooled object)
3 Processing tank 4 Pressure reducing means 5 Pressure reducing means 6 Pressure sensor 7 Product temperature sensor P1 Set pressure P2 Product temperature conversion pressure P3 Margin pressure P4 Predetermined pressure

Claims (6)

A treatment tank in which an object to be cooled is stored;
Depressurizing means for sucking and discharging the gas in the treatment tank to the outside, and decompressing the treatment tank;
A return pressure means for introducing outside air into the reduced processing tank and returning the pressure in the processing tank;
A pressure sensor for detecting the pressure in the processing tank,
The rapid cooling step of reducing the inside of the treatment tank to a set pressure, and the slow cooling step of further reducing the pressure inside the treatment tank by lowering the decompression capacity than the rapid cooling step can be executed in order.
The set pressure is set to a pressure that is higher by a margin pressure than the product temperature conversion pressure at which the saturated steam temperature in the treatment tank becomes equal to the temperature of the object to be cooled,
The margin pressure is set so as to decrease as the product temperature-converted pressure decreases. Further comprising a product temperature sensor for detecting the temperature of the object to be cooled contained in the processing tank,
The product temperature equivalent pressure is calculated based on the temperature detected by the product temperature sensor at the start of the rapid cooling process or during the rapid cooling process,
The cooling device according to claim 1, wherein the margin pressure is set to be smaller as the product temperature-converted pressure is lower. The said set pressure is set to the pressure of the setting ratio of the said product temperature conversion pressure calculated based on the detected temperature of the said product temperature sensor at the time of the said rapid cooling process start or during the said rapid cooling process. The cooling device according to 1. The set pressure is set to a pressure at which a saturated steam temperature in the processing tank is equal to a temperature obtained by adding a predetermined temperature to a temperature detected by the product temperature sensor at the start of the rapid cooling process or during the rapid cooling process. The cooling device according to claim 2. The margin pressure is set so as to decrease as the product temperature converted pressure decreases, or is set to a constant value regardless of the product temperature converted pressure,
In the quenching step, when the pressure in the processing tank reaches a pressure obtained by adding a predetermined pressure to the set pressure, a pressure reduction speed at that time is calculated, and the pressure is reduced to the set pressure while maintaining the calculated pressure reduction speed. If the pressure reduction capacity is reduced from there, the pressure reduction capacity is lowered before reaching the set pressure when it is determined that the pressure in the treatment tank falls below the product temperature equivalent pressure. The cooling device according to claim 2. A method for cooling an object to be cooled contained in a treatment tank,
A rapid cooling step of reducing the inside of the treatment tank to a set pressure, and a slow cooling step of lowering the pressure inside the treatment tank by lowering the decompression capacity than the rapid cooling step in order,
The set pressure is set to a pressure that is higher by a margin pressure than the product temperature conversion pressure at which the saturated steam temperature in the treatment tank becomes equal to the temperature of the object to be cooled,
The cooling method is characterized in that the margin pressure is set to be smaller as the product temperature converted pressure is lower.

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