JP7707639B2 - Method for controlling a vacuum cooling device - Google Patents

Description

The present invention relates to a vacuum cooling device equipped with multiple vacuum pumps.

Conventionally, there are vacuum cooling devices that vacuum-cool objects to be cooled, such as cooked foods, in a cooling tank. For example, the vacuum cooling device disclosed in Patent Document 1 is equipped with a heat exchanger for steam condensation, a water-sealed vacuum pump, and a steam ejector, and is capable of suctioning the inside of the cooling tank at low temperatures and extremely low pressures.

Japanese Patent Application Publication No. 9-296975

In a vacuum cooling device equipped with a vacuum pump and an ejector as disclosed in Patent Document 1, it is possible to use multiple vacuum pumps to perform exhaust in order to increase the exhaust speed before the steam ejector is activated and shorten the decompression time. However, as the pressure inside the cooling tank decreases, exhaust using multiple vacuum pumps becomes unnecessary, which leads to increased running costs. Also, if there is a difference in performance between multiple vacuum pumps, the pressure balance may be lost during high vacuum, and the more powerful vacuum pump may suck in outside air from the less powerful vacuum pump.

The present invention was made in consideration of these circumstances, and provides a vacuum cooling device that can appropriately drive multiple vacuum pumps when the pressure in the cooling tank decreases.

According to the present invention, a vacuum cooling device for cooling an object to be cooled contained in a treatment tank is provided, the vacuum cooling device comprising an ejector, a heat exchanger, a plurality of vacuum pumps, and a control means, the ejector is connected to the treatment tank and the vacuum pump is connected to its exhaust side via the heat exchanger, the heat exchanger is configured to condense steam exhausted from the treatment tank, the control means is configured to control the operation of the ejector and the driving of the vacuum pump, and the control means is configured to sequentially execute a first cooling step of driving the plurality of vacuum pumps to reduce the pressure inside the treatment tank, and a second cooling step of operating the ejector and stopping the driving of at least one of the plurality of vacuum pumps.

According to the present invention, by carrying out the second cooling process after the pressure in the cooling tank has been reduced by the first cooling process, it is possible to avoid operating the vacuum pump unnecessarily, reducing running costs and preventing the intake of outside air during high vacuum.

Preferably, the apparatus includes a pressure detection means for detecting the pressure inside the treatment tank and a temperature detection means for detecting the temperature of the object to be cooled, and switches from the first cooling process to the second cooling process when the pressure inside the tank detected by the pressure detection means is equal to or lower than a predetermined pressure and the temperature of the object to be cooled detected by the temperature detection means is equal to or lower than a predetermined temperature.

Preferably, a check valve is provided in the intake line of each vacuum pump.

Preferably, the system is provided with an abnormality detection means for detecting an abnormality in the vacuum pumps, and the control means continues the cooling operation by driving the other vacuum pumps even if the abnormality detection means detects an abnormality in one of the vacuum pumps.

Preferably, the control means switches the at least one vacuum pump to be stopped during the second cooling process at a predetermined timing.

1 is a conceptual diagram showing a vacuum cooling device 1 according to an embodiment of the present invention. 2 is a flowchart showing the operation of the vacuum cooling device 1 of FIG. 1 .

The following describes the embodiments of the present invention. The various features shown in the embodiments below can be combined with each other. In addition, each feature can be an invention independently.

1. Configuration of the Vacuum Cooling Device 1 First, the configuration of the vacuum cooling device 1 according to one embodiment of the present invention will be described. The vacuum cooling device 1 vacuum-cools the object F to be cooled, such as food that has been cooked, in a processing tank 2. As shown in FIG. 1, the vacuum cooling device 1 of this embodiment includes a processing tank 2, an ejector 3, a heat exchanger 4, a plurality of vacuum pumps (in this embodiment, three vacuum pumps, the first to third vacuum pumps 5A to 5C), a water supply means 6, a pressure recovery means 7, a pressure detection means 8, a temperature detection means 9, and a control means 10. In addition, the vacuum cooling device 1 of this embodiment is provided with an exhaust path 11 for exhausting gas (air and steam) in the processing tank 2 (see the thick line in the figure), and the ejector 3, the heat exchanger 4, and the first to third vacuum pumps 5A to 5C are connected to the exhaust path 11 in this order. Each configuration will be specifically described below.

The treatment tank 2 is a hollow container that can withstand reduced pressure in the internal space, and can be opened and closed with a door (not shown). The treatment tank 2 is typically formed in a roughly rectangular box shape, with the opening at the front being openable and closable with a door. By opening the door, the material to be cooled F can be put in and taken out of the treatment tank 2, and by closing the door, the opening of the treatment tank 2 can be closed airtight. Doors may be provided on both the front and back of the treatment tank 2. In the illustrated example, the material to be cooled F is contained in a food container such as a hotel pan or food container, and is stored in the treatment tank 2.

The ejector 3 has a suction port 3a, an exhaust port 3b, and a fluid inlet 3c. The ejector 3 creates a reduced pressure area by passing a fluid at high speed from a nozzle (not shown) provided at the fluid inlet 3c toward the exhaust port 3b, and sucks the fluid from the suction port 3a provided around the reduced pressure area. The ejector 3 of this embodiment is provided in the exhaust path 11, the suction port 3a is connected to the treatment tank 2, and the exhaust port 3b is connected to the heat exchanger 4, and is configured to suck and discharge the gas in the treatment tank 2 through the suction port 3a to the exhaust port 3b. The ejector 3 of this embodiment is a steam ejector, and is configured to suck the gas in the treatment tank 2 by ejecting steam supplied from the ejector steam supply path 30. Here, an ejector steam supply valve 31 is provided in the ejector steam supply path 30, and the operation of the ejector 3 can be switched by opening and closing the ejector steam supply valve 31.

The heat exchanger 4 is an indirect heat exchanger that exchanges heat without mixing the fluid in the exhaust passage 11 (fluid from the ejector 3) with the cooling water. The heat exchanger 4 can cool and condense the steam in the exhaust passage 11 with the cooling water. The cooling water is supplied from the water supply means 6 described later through the heat exchange water supply passage 40 and discharged through the heat exchange drain passage 41. The heat exchange drain passage 41 is branched into a cold water return passage 42 to a cold water tank (a water supply source for the chiller) (not shown) and a drain outlet passage 43 to the outside. The cold water return passage 42 is provided with a cold water return valve 44, and the drain outlet passage 43 is provided with a drain outlet valve 45. The cold water return valve 44 and the drain outlet valve 45 can be used to switch between returning the water after passing through the heat exchanger 4 to the cold water tank, discharging it from the drain outlet passage 43, or blocking the flow of water through the heat exchanger 4 without doing either (i.e., closing the cooling water outlet side of the heat exchanger 4).

The first to third vacuum pumps 5A to 5C are each a water-sealed vacuum pump, and are driven while being supplied with water called seal water. To supply the seal water, water is supplied to the water inlet 5x of each vacuum pump 5A to 5C from the water supply means 6, which will be described later, via a seal water supply channel 50. Here, the seal water supply channel 50 branches into three seal water supply channels 50A to 50C corresponding to each vacuum pump 5A to 5C. Each seal water supply channel 50A to 50C is provided with a seal water valve 51A to 51C and a constant flow valve 52A to 52C. Here, the constant flow valves 52A to 52C are configured to allow water to pass at a constant flow rate, as is well known.

Then, when the vacuum pumps 5A to 5C are operated while supplying water from the sealing water supply passage 50, each vacuum pump 5A to 5C draws in gas from the intake port 5y and exhausts and drains the gas to the exhaust port 5z.

The suction lines 9A-9C of the first to third vacuum pumps 5A-5C are provided with corresponding check valves 13A-13C. The check valves 13A-13C prevent gas from flowing back from the vacuum pumps 5A-5C to the suction lines 9A-9C. The check valves 13A-13C function as emergency shutoff valves to prevent gas from flowing back into the treatment tank 2 in the event of a malfunction or power outage in each of the vacuum pumps 5A-5C.

In addition, the first to third vacuum pumps 5A to 5C are provided with seal water temperature sensors 16A to 16C, respectively. The seal water temperature sensors 16A to 16C are configured to detect the temperature of the seal water (seal water temperature) present inside each vacuum pump 5A to 5C. Specifically, each seal water temperature sensor 16A to 16C can be configured, for example, by a thermocouple inserted inside each vacuum pump 5A to 5C. In this embodiment, each seal water temperature sensor 16A to 16C functions as an abnormality detection means for detecting an abnormality in each vacuum pump 5A to 5C. In other words, when the temperature detected by the seal water temperature sensor 16A to 16C becomes equal to or higher than a predetermined threshold value, the control means 10 described later is configured to determine that some abnormality has occurred in the corresponding vacuum pump 5A to 5C.

The water supply means 6 is configured to be capable of supplying room temperature water or cold water to the heat exchanger 4 and the vacuum pump 5. Here, cold water is water (chiller water) that has been cooled to a predetermined temperature by a chiller (not shown), and room temperature water is water that has not been cooled in this manner. Specifically, the water supply means 6 includes a room temperature water supply passage 60 connected to a water supply source, and a cold water supply passage 61 connected to the chiller. In addition, a room temperature water supply valve 62 is provided in the room temperature water supply passage 60, and a cold water supply valve 63 is provided in the cold water supply passage 61. In addition, a cold water temperature sensor 17 capable of detecting the temperature of the cold water is provided in the cold water supply passage 61.

The room temperature water supply line 60 and the cold water supply line 61 merge downstream of the room temperature water supply valve 62 and the cold water supply valve 63, respectively, to form a common water supply line 64. This common water supply line 64 branches into the heat exchanger water supply line 40 to the heat exchanger 4 and the seal water supply line 50 to the first to third vacuum pumps 5A to 5C. The water supply means 6 supplies cooling water to the heat exchanger 4 by opening the room temperature water supply valve 62 or the cold water supply valve 63, and further supplies water to each of the vacuum pumps 5A to 5C by opening the seal water valves 51A to 51C.

The pressure recovery means 7 is a means for introducing outside air into the depressurized treatment tank 2 to restore the pressure in the treatment tank 2. In this embodiment, the pressure recovery means 7 includes an air supply passage 70 connected to the treatment tank 2, and an air filter 71 and an air supply valve 72 are provided in the air supply passage 70, in that order from the upstream side. When the air supply valve 72 is opened while the treatment tank 2 is depressurized, outside air is introduced into the treatment tank 2 through the air filter 71, and the pressure in the treatment tank 2 can be restored. The air supply valve 72 is preferably an electric valve whose opening degree can be adjusted, and the speed of pressure recovery can be adjusted. If the air supply valve 72 is such an electric valve, it becomes possible to perform slow cooling control in which the pressure in the treatment tank 2 is reduced while adjusting the tank pressure in the first cooling step S1 and the second cooling step S2 described later.

The pressure detection means 8 is provided in the treatment tank 2. In this embodiment, the pressure detection means 8 is a pressure sensor that detects the pressure inside the treatment tank 2.

The temperature detection means 9 is provided in the treatment tank 2. In this embodiment, the temperature detection means 9 is a product temperature sensor that detects the temperature (product temperature) of the cooled object F contained in the treatment tank 2.

The control means 10 controls each of the above-mentioned components based on the detection signals of each sensor and the elapsed time. Specifically, the control means 10 controls the ejector 3 (ejector steam supply valve 31), the cold water return valve 44 and the drain outlet valve 45, the first to third vacuum pumps 5A to 5C, the seal water valves 51A to 51C, the normal temperature water supply valve 62 and the cold water supply valve 63, and the air supply valve 72. The control means 10 is also connected to a pressure detection means 8, a temperature detection means 9, and seal water temperature sensors 16A to 16C. In this embodiment, the control means 10 performs control for cooling the object to be cooled F according to a predetermined procedure (program), as described below.

The control means 10 of the above configuration can be specifically configured, for example, by an information processing device including a CPU, a memory (e.g., a flash memory), an input unit, and an output unit. Processing by each of the above-mentioned components of the control means 10 configured by the information processing device is performed by the CPU reading and executing a program stored in the memory. As the information processing device, for example, a personal computer, a PLC (programmable logic controller), or a microcomputer is used. However, some of the functions of the control means 10 may be configured to be executed on a cloud connected by any communication means.

2. Operation of the Vacuum Cooling Apparatus 1 Next, the operation of the vacuum cooling apparatus 1 of this embodiment will be described. The vacuum cooling apparatus 1 of this embodiment is configured to execute the first cooling step S1 and the second cooling step S2 under the control of the control means 10. Here, before the vacuum cooling apparatus 1 starts to operate (before the first cooling step S1 starts), all valves except the air supply valve 72 of the pressure recovery means 7 are closed. To start the operation of the vacuum cooling apparatus 1, first, the object to be cooled F is placed in the treatment tank 2, the door of the treatment tank 2 is closed airtight, and then each step is performed. Hereinafter, the operation of each step will be described in detail with reference to the flow chart of FIG. 2.

<First cooling step S1>
The first cooling step S1 is a step of depressurizing the inside of the treatment tank 2 by driving all of the first to third vacuum pumps 5A to 5C, and cooling the object to be cooled F. Specifically, the first cooling step S1 includes a room temperature water cooling step using room temperature water as sealing water, and a cold water cooling step using cold water as sealing water. In the first cooling step S1, the control means 10 first executes the room temperature water cooling step after starting the operation of the vacuum cooling device 1, and executes the cold water cooling step after the cooling has progressed. In the first cooling step S1, the control means 10 closes the ejector steam supply valve 31, so as not to operate the ejector 3. In other words, the first cooling step S1 is a step of depressurizing the inside of the treatment tank 2 only by the first to third vacuum pumps 5A to 5C, without operating the ejector 3.

When the start of operation is instructed, for example by pressing the start button (not shown) of the vacuum cooling device 1, the control means 10 first closes the air supply valve 72 in the room temperature water cooling process. Then, the control means 10 starts the first to third vacuum pumps 5A to 5C, and opens the room temperature water supply valve 62 and each seal water valve 51A to 51C of the water supply means 6. As a result, room temperature water is supplied as seal water to the first to third vacuum pumps 5A to 5C, and the three vacuum pumps 5A to 5C start reducing the pressure inside the treatment tank 2. As a result, air containing steam generated from the high-temperature cooled object F is exhausted through the exhaust path 11.

At the same time, the control means 10 also opens the drain outlet valve 45 of the drain outlet passage 43. As a result, room temperature water is also supplied from the water supply means 6 to the heat exchanger 4, and heat is exchanged between the steam from the treatment tank 2 and the room temperature water, and the steam from the treatment tank 2 is condensed and sent to the first to third vacuum pumps 5A to 5C. Meanwhile, the room temperature water that has absorbed heat in the heat exchanger 4 is discharged to the outside through the drain outlet passage 43.

When the pressure in the treatment tank 2 decreases due to the cooling in the room temperature water cooling process and the pressure in the tank detected by the pressure detection means 8 falls below a predetermined cold water supply start pressure (e.g., 20 kPa), the control means 10 transitions from the room temperature water cooling process to the cold water cooling process under this condition.

To transition to the cold water cooling process, the control means 10 specifically closes the room temperature water supply valve 62 of the water supply means 6 and opens the cold water supply valve 63 to supply cold water as sealing water to the first to third vacuum pumps 5A to 5C. The control means 10 also closes the drain outlet valve 45 and opens the cold water return valve 44 to supply cold water to the heat exchanger 4 and return the cold water that has absorbed heat in the heat exchanger 4 to the cold water tank (not shown). The water returned to the cold water tank is cooled in a chiller (not shown) and is supplied again to the cold water supply passage 61.

In the cold water cooling process, by using cold water as sealing water, the saturation pressure in the first to third vacuum pumps 5A to 5C can be reduced, improving the capacity of the first to third vacuum pumps 5A to 5C and making it possible to further reduce the pressure in the already reduced-pressure treatment tank 2. In addition, by supplying cold water to the heat exchanger 4, the gas passing through the exhaust path 11 can be condensed.

When the water seal valves 51A to 51C are motorized valves with adjustable opening, the opening of the water seal valves 51A to 51C can be adjusted to control the exhaust speed of the vacuum pump 5 and thereby the decompression speed within the treatment tank 2, and it is possible to prevent cavitation in the vacuum pump 5 while reducing the amount of cold water used.

In addition, in the vacuum cooling device 1 of this embodiment, the control means 10 monitors the seal water temperature of each vacuum pump 5A to 5C, which is detected by the seal water temperature sensors 16A to 16C as an abnormality detection means. If an abnormality is detected in any of the vacuum pumps 5A to 5C, the control means 10 stops the vacuum pump in which the abnormality was detected (e.g., the first vacuum pump 5A) and drives the vacuum pumps other than that pump (e.g., the second and third vacuum pumps 5B and 5C) to continue the cooling operation.

In addition, in the cold water cooling process, the control means 10 acquires the tank pressure detected by the pressure detection means 8 and the product temperature of the cooled material F detected by the temperature detection means 9. The control means 10 then controls to switch from the first cooling process S1 to the second cooling process S2 (see branch B1) on the condition that the tank pressure is equal to or lower than a predetermined pressure and the product temperature is equal to or lower than a predetermined temperature. Here, the predetermined pressure is, for example, 45 hPa. The predetermined temperature is, for example, 30°C. However, these predetermined pressures and temperatures can be changed as appropriate depending on the size of the treatment tank 2, the type of the cooled material F, and the exhaust capacities of the first to third vacuum pumps 5A to 5C. The predetermined pressure and temperature are set in advance before the vacuum cooling device 1 is operated, but it is preferable to store them in a memory provided in the control means 10 and to make them changeable as appropriate by accepting input from the user.

<Second cooling process>
To proceed to the second cooling step S2, the control means 10 specifically opens the ejector steam supply valve 31 to operate the ejector 3 and stops the operation of the first vacuum pump 5A and the second vacuum pump 5B. That is, the second cooling step S2 is a step of reducing the pressure in the treatment tank 2 by the ejector 3 and the third vacuum pump 5C. In addition, the control means 10 closes the corresponding sealing water valves 51A and 51B in accordance with the stop of the operation of the first vacuum pump 5A and the second vacuum pump 5B. In addition, the control means 10 keeps the cold water supply valve 63 and the cold water return valve 44 of the water supply means 6 open to continue the supply of cold water to the heat exchanger 4 and the third vacuum pump 5C. Note that a transition step of operating all the vacuum pumps 5A to 5C while operating the ejector 3 may be provided between the first cooling step S1 and the second cooling step S2. That is, in this case, the control means 10 stops driving the first vacuum pump 5A and the second vacuum pump 5B after a predetermined time has elapsed since the operation of the ejector 3.

In the second cooling step S2, by starting the ejector 3, it is possible to further reduce the pressure inside the processing tank 2 even when the tank pressure has become so low that it cannot be reduced by the first to third vacuum pumps 5A to 5C. On the other hand, once the tank pressure has become low, the exhaust capacity of the three vacuum pumps 5A to 5C is no longer necessary, so the operation of the first vacuum pump 5A and the second vacuum pump 5B is stopped and only the third vacuum pump 5C is driven.

In a configuration with multiple vacuum pumps (first to third vacuum pumps 5A to 5C) as in this embodiment, when only some of the vacuum pumps (third vacuum pump 5C) are driven, there is a risk of backflow from the stopped vacuum pumps (first and second vacuum pumps 5A, 5B) to the driving vacuum pump (third vacuum pump 5C). However, in the vacuum cooling device 1 of this embodiment, check valves 13A to 13C are provided in the suction lines 9A to 9C of the first to third vacuum pumps 5A to 5C, making it possible to prevent such backflow.

When the pressure inside the treatment tank 2 falls below the target pressure (e.g., 1.2 kPa) due to the reduction in pressure inside the treatment tank 2 in the second cooling step S2 (see branch B2 in FIG. 2), the second cooling step S2 is terminated and the cooling of the cooled object F by the vacuum cooling device 1 is stopped. To stop the cooling, specifically, the control means 10 closes the ejector steam supply valve 31, the cold water return valve 44, the drain outlet valve 45, the sealing water valve 51A, the normal temperature water supply valve 62, and the cold water supply valve 63, stops the ejector 3 and the third vacuum pump 5C, and stops the flow of water to the heat exchanger 4. After that, the air supply valve 72 is opened to restore the pressure inside the treatment tank 2 to atmospheric pressure.

In the above, an example was described in which the first and second vacuum pumps 5A and 5B are stopped and only the third vacuum pump 5C is driven in the second cooling step S2, but it is preferable to switch the vacuum pumps (5A to 5C) that are stopped in the second cooling step S2 every predetermined period. Specifically, the control means 10 rotates the vacuum pumps (5A, 5B, 5C) that are stopped in the second cooling step S2 at a predetermined timing (for example, every predetermined number of times or every predetermined period).

For example, in the second cooling step S2, the control means 10 stops the operation of the first vacuum pump 5A and the second vacuum pump 5B during the first cooling operation, stops the operation of the second vacuum pump 5B and the third vacuum pump 5C during the second cooling operation, and stops the operation of the third vacuum pump 5C and the first vacuum pump 5A during the third cooling operation. This operation reduces the difference in total operating time between the first to third vacuum pumps 5A to 5C, making it possible to reduce the risk of failure. In order to perform this control, it is preferable to store the vacuum pumps (5A, 5B, 5C) that are stopped during the cooling operation in a memory provided in the control means 10.

In addition, in the second cooling step S2, the control means 10 also monitors the seal water temperature detected by the seal water temperature sensor (e.g., seal water temperature sensor 16C) corresponding to the vacuum pump being driven (e.g., the third vacuum pump 5C). If the control means 10 detects an abnormality in the vacuum pump being driven (the third vacuum pump 5C), it stops the vacuum pump in which the abnormality is detected (the third vacuum pump 5C) and drives a vacuum pump other than that pump (e.g., the first vacuum pump 5A) to continue the cooling operation.

3. Effects As described above, in the vacuum cooling device 1 of this embodiment, the control means 10 is configured to first execute the first cooling step S1 of depressurizing the inside of the treatment tank 2 by driving the three vacuum pumps 5A to 5C, and then execute the second cooling step S2 of operating the ejector 3 and stopping the two vacuum pumps (for example, the first and second vacuum pumps 5A and 5B) on the condition that the pressure inside the tank is equal to or lower than a predetermined pressure and the product temperature of the cooled material F is equal to or lower than a predetermined temperature. With this configuration, it is possible to appropriately depressurize the inside of the treatment tank 2 even when the depressurization progresses. Specifically, when the depressurization progresses, the ejector 3 can be operated in the second cooling step S2 to further depressurize the inside of the treatment tank 2. In addition, by stopping the two vacuum pumps (5B and 5C), unnecessary driving of the vacuum pumps can be avoided, and the amount of electricity used and the amount of sealing water used can be reduced, thereby suppressing running costs.

In addition, in a vacuum cooling device 1 equipped with multiple vacuum pumps 5A-5C, if all of the first to third vacuum pumps 5A-5C continue to operate during high vacuum when the pressure is reduced, there is a risk that the more powerful vacuum pump will suck in outside air from the less powerful vacuum pump due to a delay in the operation of the check valves 13A-13C. However, in the vacuum cooling device 1 of this embodiment, it is possible to prevent such sucking in of outside air by stopping two vacuum pumps (e.g., 5B and 5C) in the second cooling step S2 during high vacuum.

In addition, in the vacuum cooling device 1 of this embodiment, even if the seal water temperature sensors 16A-16C, which serve as an abnormality detection means, detect an abnormality in any of the vacuum pumps (5A-5C), the control means 10 continues the cooling operation by driving the other vacuum pumps. Because of this configuration, even if some of the vacuum pumps (5A-5C) cannot be driven, the cooling operation can be performed by the vacuum cooling device 1 without immediately disabling the cooling operation, although the cooling time will be longer. Therefore, even if some of the vacuum pumps (5A-5C) fail, the vacuum cooling device 1 of this embodiment is capable of performing the cooling operation until the failed vacuum pump (5A-5C) is repaired.

4. Modifications The present invention can also be implemented in the following aspects.

In the above embodiment, the control means 10 transitioned from the first cooling step S1 to the second cooling step S2 on the condition that the pressure inside the tank was equal to or lower than a predetermined pressure and the product temperature was equal to or lower than a predetermined temperature. However, instead of this condition, the transition from the first cooling step S1 to the second cooling step S2 may be based on other conditions, such as the time from the start of operation or the seal water temperatures of the vacuum pumps 5A-5C detected by the seal water temperature sensors 16A-16C. The present invention is valid as long as the control means 10 controls the transition from the first cooling step S1, in which cooling is performed by multiple vacuum pumps, to the second cooling step S2, in which cooling is performed by an ejector and some vacuum pumps, under some conditions.

In the above embodiment, the seal water temperature sensors 16A-16C that detect the seal water temperature were used as the abnormality detection means for detecting abnormalities in each vacuum pump 5A-5C. However, instead of the seal water temperature sensors 16A-16C, a thermal relay may be provided in each vacuum pump 5A-5C as the abnormality detection means. Also, both the seal water temperature sensor and the thermal relay may be used as the abnormality detection means.

In the above embodiment, the first cooling process S1 includes a room temperature water cooling process in which room temperature water is supplied to the heat exchanger 4 and the vacuum pump 5, and a cold water cooling process in which cold water is supplied to the heat exchanger 4 and the vacuum pump 5. However, it is also possible to configure the first cooling process S1 to constantly supply cold water.

In the above embodiment, the ejector 3 for exhausting the gas in the treatment tank 2 is a steam ejector that ejects steam supplied from the ejector steam supply passage 30 to suck in the gas in the treatment tank 2. However, it is also possible to use a water ejector that ejects water supplied from the ejector water supply passage as the ejector.

In the above embodiment, each of the vacuum pumps 5A to 5C was a water-sealed vacuum pump. However, the vacuum pumps 5A to 5C may be of other types, such as a dry type or an oil rotary type. The vacuum pumps 5A to 5C may also be on/off controlled, or the output may be adjustable. For example, the vacuum pumps 5A to 5C may use an inverter to change the motor drive frequency and therefore the rotation speed.

In the above embodiment, check valves 13A to 13C were provided in the intake lines 9A to 9C of the vacuum pumps 5A to 5C, but instead of the check valves 13A to 13C, valves such as on-off valves or motorized valves may be used.

In the above embodiment, in the second cooling step S2, the operation of two vacuum pumps (e.g., the first and second vacuum pumps 5A and 5B) is stopped simultaneously. However, in the second cooling step S2, the operation of only one vacuum pump (e.g., the first vacuum pump 5A) may be stopped, and the pressure may be reduced using two vacuum pumps (e.g., the second and third vacuum pumps 5B and 5C). Also, in the second cooling step S2, it is also possible to first stop the operation of one vacuum pump (e.g., the first vacuum pump 5A), and then stop the operation of another vacuum pump (e.g., the second vacuum pump 5B).

In the above embodiment, the vacuum cooling device 1 is configured to include three vacuum pumps 5A to 5C. However, the number of vacuum pumps included in the vacuum cooling device 1 may be two, or four or more.

In addition, in the above embodiment, the vacuum cooling device 1 has been described as a dedicated cooling device, but as long as it has at least a vacuum cooling function, it can be modified as appropriate. For example, by providing a heating means using steam, it may be configured as a steam cooling device or a saturated steam cooking device. Alternatively, by providing a cold air cooling means using a refrigerator or a fan, it may be configured as a cold air vacuum combined cooling device.

1: Vacuum cooling device 2: Treatment tank 3: Ejector 3a: Suction port 3b: Exhaust port 3c: Fluid inlet 4: Heat exchanger 5A: First vacuum pump 5B: Second vacuum pump 5C: Third vacuum pump 5x: Water supply port 5y: Intake port 5z: Exhaust port 6: Water supply means 7: Pressure recovery means 8: Pressure detection means 9: Temperature detection means 9A to 9C: Intake line 10: Control means 11: Exhaust passages 13A to 13C: Check valves 16A to 16C: Sealing water temperature sensor 17: Cold water temperature sensor 30: Ejector steam supply passage 31: Ejector steam supply valve 40: Heat exchanger water supply passage 41: Heat exchanger drain passage 42: Cold water return passage 43: Drain outlet passage 44: Cold water return valve 45: Drain outlet valve 50, 50A to 50C : Seal water supply channel 51A to 51C : Water seal valve 52A to 52C : Constant flow valve 60 : Room temperature water supply channel 61 : Cold water supply channel 62 : Room temperature water supply valve 63 : Cold water supply valve 64 : Common water supply channel 70 : Air supply channel 71 : Air filter 72 : Air supply valve B1, B2 : Branch F : Cooled object S1 : First cooling process S2 :Second cooling process

Claims (5)

A method for controlling a vacuum cooling device that cools an object to be cooled contained in a treatment tank, comprising the steps of:
The vacuum cooling device includes an ejector, a heat exchanger, a plurality of vacuum pumps, and a control means.
the ejector is connected to the treatment tank, and the vacuum pump is connected to an exhaust side of the ejector via the heat exchanger;
The heat exchanger is configured to condense steam exhausted from the treatment tank,
the control means is configured to be able to control the operation of the ejector and the drive of the vacuum pump,
A control method for a vacuum cooling apparatus, comprising the steps of: using the control means to sequentially execute a first cooling process of driving the plurality of vacuum pumps to reduce pressure inside the processing tank; and a second cooling process of operating the ejector and stopping the driving of at least one of the plurality of vacuum pumps. A method for controlling a vacuum cooling device according to claim 1, comprising the steps of:
The vacuum cooling device includes a pressure detection means for detecting an internal pressure of the treatment tank and a temperature detection means for detecting a temperature of the object to be cooled,
A control method for a vacuum cooling device, in which the control means switches from the first cooling process to the second cooling process under the condition that the pressure inside the tank detected by the pressure detection means is equal to or lower than a predetermined pressure and the temperature of the object to be cooled detected by the temperature detection means is equal to or lower than a predetermined temperature. A method for controlling a vacuum cooling device according to claim 1 or 2, comprising:
The vacuum cooling apparatus includes a check valve provided in the intake line of each vacuum pump. A method for controlling a vacuum cooling apparatus according to any one of claims 1 to 3, comprising the steps of:
The vacuum cooling device includes an abnormality detection means for detecting an abnormality in the vacuum pump,
The control method for a vacuum cooling device, wherein even if the abnormality detection means detects an abnormality in one of the vacuum pumps, the control means drives the other vacuum pumps to continue the cooling operation. A method for controlling a vacuum cooling device according to any one of claims 1 to 4, comprising:
The method for controlling a vacuum cooling apparatus, wherein the control means switches the at least one vacuum pump to be stopped in the second cooling step at a predetermined timing.