JP4271791B2 - Vacuum cooling device with heat exchanger for vapor condensation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum cooling apparatus having a heat exchanger for vapor condensation.
[0002]
[Prior art]
There is a vacuum cooling device as a device for cooling food. The vacuum cooling device stores food to be cooled in a processing tank connected to a vacuum generator, and vaporizes moisture in the food by evacuating the inside of the processing tank, thereby cooling the food. In the case of vacuum cooling, the final temperature of the food to be cooled is determined by the degree of vacuum in the treatment tank, and the higher the degree of vacuum, the lower the temperature can be cooled. In the case of depressurization by the water ejector, the depressurization in the treatment tank is performed by circulating the circulating water stored in the water tank between the ejector and the water tank. In this case, in the low vacuum state, air can be sucked even if the temperature of the circulating water is slightly high. However, if the degree of vacuum is high, if the temperature of the circulating water is high, there is evaporation from the circulating water. It becomes impossible to perform suction. Therefore, when food is cooled to a lower temperature, it is necessary to lower the temperature of the circulating water, and the circulating water is cooled by a water cooling device such as a chiller.
[0003]
In addition, since the vacuum cooling is to lower the temperature by sucking air from the inside of the processing tank and vaporizing moisture in the food, the vacuum generator sucks the steam generated from the food together with the air in the processing tank. There is a need. However, if suction is performed in the state of steam, the volume of air that can be sucked is reduced and the efficiency of air suction is reduced, so a steam condensation heat exchanger is provided in the middle of the vacuum pipe, and heat exchange for steam condensation is performed. The cooling water is sent to the vessel to condense the negative pressure steam in the vacuum pipe and improve the efficiency of air suction.
[0004]
The cooling water supplied to the steam condensing heat exchanger is more efficient for condensing steam than water cooled at room temperature, so the cold water generated by the water cooling device can be sent to the steam condensing heat exchanger. Has been done. If the food temperature at the end of the cooling process is low, the temperature of the cooling water that has passed through the heat exchanger for steam condensation is slight because the temperature of the steam in the vacuum pipe is low, but the food temperature is high In this case, the temperature of the cooling water is greatly increased by the heat exchanger for steam condensation. Since enormous energy is required to cool the cooling water whose temperature has greatly increased, the cooling water after passing through the heat exchanger for steam condensation is discarded, and a lot of water is used. Since it is necessary to send a large amount of cooling water to the heat exchanger for steam condensation, a large amount of cold water is required, and a large-capacity water cooling device has been used.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to reduce the amount of cooling water used in the heat exchanger for steam condensation in a vacuum cooling device having the heat exchanger for steam condensation.
[0006]
[Means for Solving the Problems]
A processing tank that contains food inside, a vacuum generator that sucks air in the processing tank, a vacuum pipe that connects the processing tank and the vacuum generator, a heat exchanger for vapor condensation in the middle of the vacuum pipe, and a heat exchanger for vapor condensation A cooling water supply pipe for supplying cooling water to the water, a cooling water control valve in the middle of the cooling water supply pipe, and an operation control device for controlling the operation of each device. The operation control device operates the vacuum generator at the initial step, but does not supply the cooling water to the steam condensation heat exchanger, and the operation control device does not supply the vacuum generator at the later step after the initial step. Operation and control to supply cooling water to the steam condensation heat exchanger.
[0007]
In addition, a water cooling device that generates cold water, a heat exchanger for semi-cold water that cools room temperature water with cold water generated by the water cooling device to generate semi-cooled water, a heat exchanger for steam condensation of cold water generated by the water cooling device A cooling water control valve for controlling the cooling water side that controls the supply to the water, and a cooling water control valve for the cooling water side that controls the supply to the heat exchanger for steam condensation of the semi-cooling water generated by the heat exchanger for the semi-cooling water are also provided in the vacuum cooling process The operation control device operates the vacuum generator during the initial process, but does not supply cooling water to the steam condensation heat exchanger. At the middle stage to be performed, the operation of the vacuum generator and the control to open the semi-cold water side cooling water control valve are performed, and at the final stage to be performed after the middle stage process, the operation of the vacuum generator and the control to open the cold water side cooling water control valve are performed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. 1 and 2 are those related to one embodiment of the present invention. First, a description will be given with reference to FIGS. FIG. 1 is a schematic configuration diagram of a vacuum cooling device in one embodiment, and FIG. 2 is an explanatory diagram of a change in vacuum degree and a change in food temperature in one embodiment.
[0014]
The treatment tank 2 for containing a food product on the inner portion connects the vacuum pipe 9, the other end of the vacuum pipe 9 is branched into two, one room-temperature side ejector 1a, the other is connected to the cold side ejector 1b To do. A steam condensation heat exchanger 6 is provided in the middle of the vacuum pipe 9, and cooling water is supplied through a cooling water supply pipe 11 connected to the steam condensation heat exchanger 6. The cooling water supply pipe 11 is connected with a quasi-cold water supply pipe 11a and a chilled water supply pipe 11b. A cooling water control valve 12b is provided.
[0015]
The room temperature side ejector 1a is connected to the room temperature water tank 3a, and a room temperature side circulation pump 8a is provided in the middle of the room temperature side circulation pipe 10a and the room temperature side circulation pipe 10a for sending the circulating water in the room temperature water tank 3a to the room temperature side ejector 1a. The low temperature side ejector 1b is connected to the low temperature side circulating water tank 3b, and a low temperature side circulating pump 8b is provided in the middle of the low temperature side circulating pipe 10b that sends the circulating water in the low temperature side circulating water tank 3b to the low temperature side ejector 1b. Provide. The original side of the quasi-cold water supply pipe 11a is connected downstream of the normal temperature side circulation pump 8a of the normal temperature side circulation pipe 10a, and the original side of the cold water supply pipe 11b is downstream of the low temperature side circulation pump 8b of the low temperature side circulation pipe 10b. Semi-cold water heat exchange is performed in which heat is exchanged between the cooling water sent by the semi-cold water supply pipe 11a and the cold water stored in the low-temperature water tank 3b in the middle of the room temperature side circulation pipe 10a. A vessel 13 is provided.
[0016]
A water cooling device 4 is connected to the low temperature side circulating water tank 3b so that the cold water generated by the water cooling device 4 can be stored in the low temperature side circulating water tank 3b. A cooling water circulation pipe 15 is connected downstream of the steam condensation heat exchanger 6 of the cooling water supply pipe 11 and the other end of the cooling water circulation pipe 15 is connected to the low temperature water tank 3b. A drainage control valve 5 is provided downstream of the steam condensation heat exchanger 6 in the cooling water supply pipe 11, and the cooling water that has passed through the water vapor condensation heat exchanger 6 is directly drained by the drainage control valve 5. Control is made as to whether or not the coolant is circulated and reused. The room temperature side circulation pump 8a, the low temperature side circulation pump 8b, the semi-cold water side cooling water control valve 12a, the cold water side cooling water control valve 12b, the water cooling device 4, and the drainage control valve 5 are connected to each other, and a timer device 14 is provided therein. The operation of the vacuum cooling device is controlled by the operation control device 7 that is held.
[0017]
The operation process of vacuum cooling is divided into an initial process, a middle process, and a final process. The initial process is 1 minute from the start of operation, the intermediate process is 4 minutes from the end of the initial process, and the final process is 10 minutes from the end of the intermediate process. The operation control device 7 starts the operation of the water cooling device 4 in advance before starting the vacuum cooling, and the water in the low temperature side water tank 3b is kept at about 3 ° C. cold water.
[0018]
When a vacuum cooling start signal is input to the operation control device 7, the operation control device 7 first performs an initial process, starts operation of the room temperature side circulation pump 8 a, and starts measuring time by the timer device 14. In addition, the water cooling device 4 operated before starting the initial process continues to operate throughout all the processes.
[0019]
By the operation of the room temperature side circulation pump 8a, the room temperature circulation water stored in the room temperature water tank 3a is sent to the room temperature side ejector 1a through the room temperature side circulation pipe 10a. Since the circulating water sent to the room temperature side ejector 1a passes through the room temperature side ejector 1a, the air in the processing tank 2 connected by the vacuum pipe 9 is sucked and vacuumed in the processing tank. The degree will rise. At this time, since the semi-cold water side cooling water control valve 12a remains closed, the cooling water is not sent to the heat exchanger 6 for steam condensation.
[0020]
When the timer device 14 outputs that one minute has passed since the start of the initial process, the operation control device switches the operation process from the initial process to the intermediate process, and the operation control apparatus 7 opens the semi-cold water side cooling water control valve 12a to Control to open the drain side of the control valve 5 is performed. When the semi-cold water side cooling water control valve 12a is opened, a part of the circulating water that is driven in the normal temperature side circulation pipe 10a by the normal temperature side circulation pump 8a is supplied to the semi-cold water supply pipe 11a branched from the circulation pipe 10. Then, the cooling water is supplied to the heat exchanger 6 for condensing steam.
[0021]
Since the semi-cold water heat exchanger 13 is provided in the middle of the semi-cold water supply pipe 11a, the room temperature water that has reached the semi-cold water heat exchanger 13 exchanges heat with the cold water in the low-temperature side water tank 3b. The chilled water becomes lower than the temperature but higher than the temperature of the chilled water, and the quasi-cooled water is supplied to the heat exchanger 6 for steam condensation. The semi-cooled water supplied to the steam condensation heat exchanger 6 cools and condenses the steam in the vacuum pipe 9, and the temperature of the semi-cooled water is increased by heat exchange. The cooling water whose temperature has risen is drained through the drainage control valve 5.
[0022]
When the timer device 14 outputs that 4 minutes have passed since the start of the medium-term process, the operation control device 7 switches the operation process from the medium-term process to the final process, and the operation control device 7 stops the normal temperature side circulation pump 8a and subcooled water. The side cooling water control valve 12a is closed, the low temperature side circulation pump 8b is operated, the cold water side cooling water control valve 12b is opened, and the cooling water circulation pipe 15 side of the drainage control valve 5 is controlled to open.
[0023]
When the pressure in the treatment tank decreases, the moisture in the food begins to evaporate. As shown in FIG. 2 , the change in food temperature hardly changes immediately after the start of operation, but when the saturation temperature becomes lower than the food temperature and the evaporation of moisture starts, the food temperature is drastically lowered because heat is taken away during evaporation. Go. In the case of the initial process, since steam is hardly generated from the food, it is not necessary to supply cooling water to the heat exchanger 6 for steam condensation. Therefore, the cooling water is not supplied to the steam condensation heat exchanger 6 until the degree of vacuum rises to some extent from the start of operation, and cooling is performed 1 minute after the start of the initial process, which is the time when the moisture in the food starts to evaporate. By performing control to start supply of irrigation water, the amount of cooling water used can be reduced.
[0024]
In the case of a medium-term process where the food temperature is high, steam having a relatively high temperature is sent to the vacuum pipe 9, and the temperature of the semi-cooled water supplied to the heat exchanger 6 for steam condensation rises greatly due to heat exchange with the steam. . Since the high-temperature water cannot be used for the cooling water for the heat exchanger 6 for steam condensation or the circulating water for the room temperature side ejector, the cooling water whose temperature has risen greatly is drained through the drainage control valve 5.
[0025]
Since the steam temperature in the vacuum pipe 9 is relatively high during the medium-term process, the cooling water can sufficiently condense the steam even with sub-cooled water slightly lower than room temperature, but the cooling water that has passed through the steam condensation heat exchanger 6 is A large amount is required because the temperature is high and cannot be reused. When the cold water stored in the low temperature side water tank 3b is exchanged with the normal temperature water, the normal temperature water side cannot bring the water temperature to the temperature of the cold water, and the temperature drop is small, but in this case the cold water side Many semi-cold waters can be obtained while keeping the temperature rise width of the water low. Although the cooling water does not have to be very low during the medium-term process, a large amount of cooling water is necessary. Therefore, a large amount of semi-cold water can be obtained by performing heat exchange with the cold water. When sending chilled water to the heat exchanger 6 for steam condensation during the mid-term process, a large amount of chilled water had to be prepared. However, the chilled water was not sent directly, and the amount of chilled water was not reduced. There is no need to increase the capacity of the device 4 or the volume of the water tank. In addition, since the water cooling device 4 continues to operate, the cold water temperature in the low temperature side water tank 3b can be kept low.
[0026]
In the final stage where the food temperature is already low, the degree of vacuum cannot be increased unless the circulating water sent to the low temperature ejector 1b is also cold water. In the case of the final process, since the steam having a relatively low temperature is sent to the vacuum pipe 9, the steam cannot be condensed unless cold water having a low temperature is supplied to the steam condensation heat exchanger 6. The temperature rise of the cooling water is slight. When the cooling water is sent to the steam condensation heat exchanger 6 as cooling water, the temperature of the cooling water that has passed through the steam condensation heat exchanger 6 is lower than the normal temperature, and is returned to the low temperature water tank 3b through the drainage control valve 5. Therefore, the water temperature in the low temperature side water tank 3b can be made lower than when the room temperature water is supplied to the low temperature side water tank 3b. By returning the cooling water to the low temperature water tank 3b, it can be reused as cooling water or circulating water to the low temperature ejector.
[0027]
The temperature and amount of cooling water required differ between the mid-term process and the final process. By supplying cooling water according to each process, the amount of energy and water required for cooling water cooling are used. The amount can be reduced.
[0028]
Further, since the supply of the cooling water to the steam condensation heat exchanger 6 is branched from the normal temperature side circulation pipe 10a or the low temperature side circulation pipe 10b, the cooling water is sent to the steam condensation heat exchanger 6 There is no need to provide a dedicated pump.
[0029]
【The invention's effect】
By implementing this invention, the usage-amount of the cooling water of the heat exchanger for steam condensation can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a configuration of a vacuum cooling device according to an embodiment of the present invention.
1 Ejector 2 Processing tank
3a Room temperature water tank
3b Low temperature side circulating water tank 4 Water cooling device 5 Drain control valve 6 Heat exchanger for steam condensation 7 Operation control device
8a Room temperature side circulation pump
8b Low-temperature side circulation pump 9 Vacuum piping
10a Room temperature side circulation piping
10b Low-temperature side circulation piping 11 Cooling water supply piping
12a Semi-cold water side cooling water control valve
12b Cooling water side cooling water control valve 13 Semi-cold water heat exchanger 14 Timer device 15 Cooling water circulation piping

Claims (2)

A processing tank that contains food, a vacuum generator that sucks air in the processing tank, a vacuum pipe that connects the processing tank and the vacuum generator, a heat exchanger for steam condensation in the middle of the vacuum pipe, and water cooling that generates cold water Cooling water at room temperature with cold water generated by the water cooling device , the temperature of the cold water is lower than the temperature of the normal water but higher than the temperature of the cold water. Cooling water supply piping for supplying cooling water to the exchanger, cold water side cooling water control valve that controls the supply of cold water generated by the water cooling device to the steam condensation heat exchanger, quasi-chilled water heat exchanger A semi-cold water cooling water control valve that controls the supply of cold water to the steam condensation heat exchanger and an operation control device that controls the operation of each device. The operation control device is divided into final stages. The vacuum generator is activated during the initial process, but the cooling water is not supplied to the steam condensation heat exchanger, and the vacuum generator is activated and the quasi-cold water-side cooling water control valve is opened during the intermediate process after the initial process. A vacuum cooling apparatus having a heat exchanger for condensing steam, which performs control and performs control of opening a vacuum generator and opening a cooling water-side cooling water control valve at the final stage after the middle stage. 2. A vacuum cooling device having a heat exchanger for vapor condensation according to claim 1 , wherein the vacuum generator is an ejector-type vacuum generator comprising an ejector, a circulation pump, a water tank, and a circulation pipe. The cooling water supply pipe for supplying the cooling water to the condenser is connected to one end of the circulation pipe, and a part of the circulating water sent through the circulation pipe is branched and supplied to the heat exchanger for steam condensation. A vacuum cooling device with a heat exchanger for vapor condensation.

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