JP2015169374A - Vacuum cooling apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a more precise pressure control when an inside part of a processing tank is kept at a set pressure under a high vacuum state of a final stage of vacuum cooling process.SOLUTION: This invention relates to a vacuum cooling apparatus for cooling an object 7 to be cooled that is stored in a processing tank 2 by making vacuum in the processing tank 2. There is provided in advance a surrounding air taking valve 3 for taking in the surrounding air in order to adjust a pressure reducing capability at a vacuum generating device 1. In order to hold the pressure in the processing tank under a state in which the inside of the processing tank is kept under a high vacuum, when a measured pressure in the processing tank is lower than a target pressure, an operation for opening the surrounding air taking-in valve 3 to increase an opening degree and in turn when the measured pressure in the processing tank is higher than the target pressure, an operation for closing a degree of opening of the surrounding air taking-in valve 3 is carried out and an operating amount is adjusted by a slight motion for an opening action and a wide motion for a closing action in respect to the operating amount of the surrounding air taking-in valve 3.

Description

The present invention accommodates an object to be cooled such as cooked food in a processing tank, evaporates moisture in the object to be cooled by reducing the pressure in the processing tank, and rapidly heats the object to be cooled by heat of vaporization due to evaporation. The present invention relates to a vacuum cooling device that cools the air.

As described in Japanese Patent No. 4924147, the gas in the processing tank containing the object to be cooled is exhausted to the outside, and the inside of the processing tank is decompressed to lower the saturation temperature in the processing tank. 2. Description of the Related Art A vacuum cooling device is known that uses the heat of vaporization to cool a food by promoting moisture evaporation. In food service centers, etc., when cooling cooked foods, it is required to pass through a temperature zone where bacteria can easily propagate as soon as possible. If it is a vacuum cooling device, it cools to the center of the object to be cooled in a short time. Is widely used because it is possible. However, when the liquid object to be cooled is vacuum-cooled, if the pressure is rapidly reduced, bumping occurs in the object to be cooled. In that case, the object to be cooled may scatter and the yield may decrease.

In the vacuum cooling device, the treatment tank and the vacuum generator are connected via a vacuum pipe, and the gas in the treatment tank is discharged and reduced in pressure by operating the vacuum generator. It is difficult to adjust. Therefore, an outside air intake pipe provided with an outside air intake valve is connected to the processing tank, and the outside pressure is taken in via the outside air intake pipe, so that the decompression speed is adjusted. When the outside air intake valve is opened during exhaust by the vacuum generator, outside air is taken into the treatment tank through the outside air intake pipe. In addition to the gas in the treatment tank, the outside air introduced from the outside air intake pipe is also exhausted by the vacuum generator. Will do. Therefore, the decompression speed in the treatment tank is reduced. By increasing or decreasing the amount of outside air introduced from the outside air intake valve, the decompression speed in the treatment tank can be adjusted, and if the outside air intake valve is increased to increase the amount of outside air intake, the decompression speed increases. If the opening degree of the outside air intake valve is decreased to reduce the outside air intake amount, the decrease in the decompression speed is reduced. By performing such slow cooling control (operation of the outside air intake valve) during decompression, the decompression speed can be adjusted, and bumping of the object to be cooled can be prevented.

The invention of Japanese Patent No. 4924147 describes the following problems. When the gas in the processing tank is exhausted to the outside depending on the capacity of the decompression means, the inside of the processing tank is depressurized until the pressure in the processing tank reaches a saturated vapor pressure lower than the cooling set temperature. Therefore, there is a risk of overcooling the foodstuff. In addition, temperature unevenness may occur depending on the position of the temperature sensor inserted into the food, and depending on the location, there is a risk of excessive cooling or insufficient cooling. Furthermore, since there is a difference in temperature drop depending on the type of food, if different kinds of food are cooled at the same time, temperature unevenness may occur, which may cause excessive cooling or insufficient cooling. In addition, even if the same food is used, a portion that is easily cooled and a portion that is difficult to cool appear depending on the size, position in the container, and the degree of clogging. This may cause

In the invention of Japanese Patent No. 4924147, in response to the above-mentioned problem, “after the pressure inside the processing tank is reduced by the pressure reducing means until the cooling target temperature is detected, the product temperature by the temperature sensor maintains the cooling holding temperature, or And a control means for controlling the decompression means and / or the return pressure means so that the pressure in the processing tank by the pressure sensor maintains a saturated vapor pressure corresponding to the cooling holding temperature. . In this case, after reducing the pressure in the treatment tank until the product temperature reaches the cooling target temperature, the product temperature is controlled to maintain the cooling holding temperature, or the processing tank pressure is controlled to maintain a saturated vapor pressure corresponding to the cooling holding temperature. The In this way, the level of pressure reduction in the processing tank by the pressure reducing means is regulated, and the maintenance of the pressure or temperature is controlled, so that excessive or insufficient cooling of the foodstuffs and temperature unevenness can be suppressed. .

In the case where the pressure in the treatment tank is maintained at the target pressure, the opening degree of the outside air intake valve is adjusted based on the pressure in the treatment tank as in the case of the slow cooling control, and the pressure reduction speed is adjusted. By appropriately operating the outside air intake valve, it is possible to perform slow cooling and pressure holding during decompression, and to prevent over- and under-cooling. However, it is not easy to maintain the pressure in the processing tank in a high vacuum state at a set pressure. In order to adjust the pressure in the treatment tank, the vacuum generator is operated with a constant capacity, and the opening degree of the outside air intake valve is adjusted based on the pressure measured by the pressure sensor. Since the state of the object to be cooled is constantly changing, such as the amount of steam generated decreases as the temperature of the product decreases, the pressure inside the treatment tank is detected and the pressure reduction rate is adjusted to detect the inside of the treatment tank. Keep the pressure at the target pressure. When the outside air intake valve is moved in the opening direction and the outside air intake amount from the outside air intake valve is increased, the exhaust amount from the inside of the processing tank is reduced by the vacuum generator, and thus the decompression speed in the processing tank is reduced. If the amount of exhaust from the treatment tank is less than the amount of steam generated from the object to be cooled, the pressure in the treatment tank will increase. When the pressure in the processing tank is lower than the target pressure, the amount of outside air taken in is increased to increase the pressure in the decompression processing tank.

On the other hand, when the outside air intake valve is moved in the closing direction and the outside air intake amount from the outside air intake valve is decreased, the amount of exhaust from the inside of the processing tank is increased in the vacuum generator, so that the decompression speed in the processing tank increases. When the pressure in the treatment tank is higher than the set pressure, the amount of outside air taken in is reduced to lower the pressure in the decompression treatment tank.

By adjusting the opening of the outside air intake valve based on the pressure value in the treatment tank, the pressure in the treatment tank is controlled to draw a curve that moves up and down across the set pressure. As shown, the curve tends to be biased toward the side where the degree of vacuum is insufficient. In this case, since the degree of vacuum is maintained in a state of being insufficient, cooling is insufficient.

Japanese Patent No. 4924147

The problem to be solved by the present invention is that when the inside of the treatment tank is held at the target pressure, it is possible to prevent the deviation between the pressure inside the treatment tank and the target pressure from increasing, and to perform more precise pressure control. The object is to provide a vacuum cooling device.

The invention according to claim 1 has a processing tank for storing an object to be cooled, a pressure measuring device for measuring the pressure in the processing tank, and a vacuum generator for discharging the gas in the processing tank, and the inside of the processing tank is decompressed. Thus, a vacuum cooling device that cools an object to be cooled stored in a processing tank, and an outside air intake valve that takes in outside air is provided in order to adjust the pressure reduction capability of the vacuum generator during cooling operation. In a vacuum cooling device that adjusts the pressure reduction capacity by operating the opening of the intake valve, aiming to maintain the processing tank pressure at the target pressure while the processing tank is in a high vacuum state. When the measured pressure in the tank is lower than the target pressure, the opening degree of the outside air intake valve is opened, and when the measured pressure in the processing tank is higher than the target pressure, the opening degree of the outside air intake valve is set. What to close There are, the operation amount of the outside air uptake valves move small to the side opening, and wherein the closed to the side are those by weighting the operation amount to move large.

According to the second aspect of the present invention, in the vacuum cooling apparatus described above, when the operation of opening the outside air intake valve is performed because the measured pressure in the processing tank is lower than the target pressure, the outside air intake valve is set to a predetermined value. When the operation amount A is opened every time and the measured pressure in the processing tank is higher than the target pressure, and the opening degree of the outside air intake valve is closed, the outside air intake valve is opened every predetermined time. The operation amount A is closed by the operation amount B, and the operation amount A when the outside air intake valve is opened is smaller than the operation amount B when the outside air intake valve is closed.

Even when the outside air intake valve is opened relatively large in a state where the pressure in the processing tank is high, the amount of exhaust in the processing tank by the vacuum generator is large. In the state where the pressure in the tank has become low, if the opening degree of the outside air intake valve is opened by the same amount, the exhaust amount from the inside of the processing tank will be greatly reduced, and a relatively rapid pressure increase will occur in the processing tank. It turns out that. For example, when performing slow cooling control in the early stage of vacuum cooling where the pressure in the processing tank is high, the vacuum generator can exhaust a large amount of gas from the processing tank, and 100 gases per second from the processing tank. Even if 10 outside air is taken in from the outside air intake valve as being exhausted, the decompression speed in the processing tank is only slightly reduced. However, as the cooling process progresses and the pressure in the processing tank decreases, the amount of gas that can be exhausted from the processing tank decreases even if the vacuum generator operates in the same way, and 1 gas per second from the processing tank. In a state where only exhaust is possible, if 10 outside air enters from the outside air intake valve, the pressure reduction in the treatment tank does not proceed, but the pressure rises conversely.

Therefore, if the opening operation of the outside air intake valve for maintaining the pressure during high vacuum is performed in the same way as the slow cooling control during decompression, the direction in which the pressure in the treatment tank is increased changes with a large inclination. This means that the pressure in the treatment tank changes only with a small inclination in the direction of decreasing the pressure. In the present invention, when the pressure is maintained in a high vacuum state, the operation amount is weighted differently when the opening degree of the outside air intake valve is opened and closed. When the opening of the outside air intake valve is opened to increase the pressure in the treatment tank, the amount of increase in opening is reduced when the opening of the outside air intake valve is closed to lower the pressure in the treatment tank. It is smaller than the amount. If it does in this way, when opening an external air intake valve, it will be opened very little by little, and it is prevented that the pressure in a processing tank increases rapidly. And when closing an outside air intake valve, since it closes larger than when opening, the pressure in a processing tank can be reduced more rapidly.

By carrying out the present invention, when maintaining the pressure in the treatment tank at the target pressure, it is possible to prevent the deviation from the target pressure from becoming large, and the actual pressure is biased toward the higher side with respect to the target pressure. Disappear. Since holding at the target pressure can be performed more precisely, proper vacuum cooling can be performed without excessive or insufficient cooling.

Flow diagram of a vacuum cooling device implementing the present invention Pressure transition diagram in the treatment tank in one embodiment of the present invention Transition diagram of pressure in treatment tank in conventional vacuum cooling system

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow chart of a vacuum cooling apparatus embodying the present invention, and FIG. 2 is a pressure transition diagram in a processing tank in one embodiment of the present invention. The vacuum cooling device has a processing tank 2 that accommodates an object 7 to be cooled and a vacuum generator 1 that discharges gas in the processing tank 2. The vacuum cooling device evaporates the water in the object to be cooled by reducing the pressure in the processing tank, and cools the object to be cooled 7 accommodated in the processing tank 2 by heat of vaporization at the time of evaporation.

The vacuum generator 1 is connected to the processing tank 2 by a vacuum pipe 9, and the gas in the processing tank 2 is discharged through the vacuum pipe 9 by operating the vacuum generator 1. A heat exchanger 10 for cooling the gas sucked from the processing tank 2 is provided in the middle of the vacuum pipe 9. The gas sucked from the treatment tank contains steam, and when water becomes steam, the volume is significantly increased. Therefore, a large volume of steam is sent to the vacuum generator 1 as it is. Becomes less efficient. For this purpose, a heat exchanger 10 is provided in the vacuum pipe 9, the suction gas is cooled by the heat exchanger 10, the vapor is condensed, and the volume of the gas that must be discharged by the vacuum generator 1 is reduced. A chilled water generator 11 that supplies chilled water for cooling is connected to the heat exchanger 10 so that the chilled water is circulated between the cold water generator 11 and the heat exchanger 10. The condensed water separated by the heat exchanger 10 is stored in the condensed water tank 8 installed below the heat exchanger 10, and is discharged from the condensed water tank 8 after the cooling operation is completed.

In addition, when the object to be cooled 7 is liquid, if the pressure in the processing tank 2 is rapidly reduced, bumping occurs in the object 7 to be cooled and the object to be cooled scatters. Allow slow cooling control. In the slow cooling control, an outside air intake pipe 4 provided with an outside air intake valve 3 is connected to the treatment tank 2 and the outside air is introduced into the treatment tank 2 by opening the outside air intake valve 3 during the cooling operation. By doing. When the outside air is introduced through the outside air intake valve 3, the amount of exhaust in the processing tank 2 decreases, and the pressure reduction speed in the processing tank 2 decreases.

The processing tank 2 is provided with a pressure measuring device 5 for measuring the pressure in the processing tank. The pressure in the processing tank measured by the pressure measuring device 5 is output to the operation control device 6 that controls the operation of the vacuum cooling device. The operation control device 6 operates the vacuum cooling device by controlling each device of the vacuum cooling device such as the vacuum generator 1 and the outside air intake valve 3. In the operation control device 6, each device is controlled based on the elapsed time, the temperature of the object 7 to be cooled, and the pressure in the treatment tank measured by the pressure measuring device 5.

In the cooling operation in which slow cooling is not performed, the outside air intake valve 3 is closed, and the pressure of the vacuum generator 1 is reduced as it is to reduce the inside of the processing tank to the target pressure. If the object to be cooled 7 does not cause bumping, the cooling can be performed faster without performing the slow cooling control. However, if rapid depressurization causes bumping to occur in the object to be cooled, slow cooling control is required. When performing slow cooling control to prevent bumping of the object 7 to be cooled, a processing tank in which an elapsed time and a target pressure in the processing tank at that time are set in the operation control device 6 and measured by the pressure measuring device 5. By adjusting the opening degree of the outside air intake valve 3 so that the internal pressure value becomes the target pressure, the cooling operation is performed while adjusting the pressure reduction speed.

Even when the slow cooling control is not performed, the opening degree of the outside air intake valve 3 is adjusted in order to maintain the pressure inside the processing tank at the target pressure. When the operation of the vacuum generator 1 is stopped, the pressure in the processing tank 2 increases. However, when the operation is performed with the capacity of the vacuum generator 1 as it is, the pressure in the processing tank is excessively decreased. Therefore, the operation of the vacuum generator 1 is continued, and the pressure reduction speed is adjusted by adjusting the amount of outside air taken in from the outside air taking-in valve 3 so that the pressure in the processing tank 2 is maintained at the target pressure.

When the pressure in the processing tank is lower than the target pressure, the pressure adjustment is performed by operating the outside air intake valve 3 in the opening direction to lower the pressure reduction capacity and increase the pressure in the processing tank. If it becomes higher than that, the pressure reduction capability is increased by operating the outside air intake valve 3 in the closing direction, and the pressure in the processing tank is decreased. At this time, the amount of operation performed in the direction to close the outside air intake valve when the measured pressure value is higher than the target value is different from the amount of operation performed in the direction to open the outside air intake valve when the measured pressure value is lower than the target value. Keep it. In a high vacuum state, the pressure in the treatment tank immediately rises even if the opening of the outside air intake valve is slightly increased. However, if the pressure in the treatment tank is to be reduced, the outside air Even if the opening of the intake valve is slightly closed, the pressure in the treatment tank does not easily decrease. Therefore, the operation amount when opening the outside air intake valve is reduced, and the operation amount when closing the outside air intake valve is increased.

For example, when the pressure in the processing tank is increased because the measured pressure is lower than the target pressure, an operation of opening the opening of the outside air intake valve 3 by 1 every second is performed, and conversely, the measured pressure is lower than the target pressure. If the pressure in the processing tank is to be lowered because of the high pressure, the opening degree of the outside air intake valve 3 is set to perform an operation of closing 10 times per second. With this setting, when the outside air intake valve 3 is opened, it is gradually opened, and when it is closed, it is closed faster.

FIG. 2 shows an image of a change in pressure value when the above-described weighting is applied to the operation amount of the outside air intake valve, and FIG. 3 is an image of a change in pressure value when the above weighting is not applied to the operation amount of the outside air intake valve. Is described. 2 and 3, it is assumed that the same movement is observed in a portion where the pressure in the processing tank at the initial stage of the vacuum cooling process is rapidly reduced to a part where the pressure is gradually reduced in the middle of the vacuum cooling process. And both differ in the part which expanded and displayed the change of the pressure value in a processing tank in the last stage of the vacuum cooling process which hold | maintains the pressure in a processing tank at a target pressure. In both cases, the pressure value in the treatment tank is the same in that it moves up and down across the target value, but differs in the point of inclination and deviation.

In FIG. 3 in which the operation amount of the outside air intake valve is not weighted, for example, when the pressure in the processing tank is increased because the measured pressure is lower than the target pressure, the opening degree of the outside air intake valve 3 is set. In the case of performing an operation to open 5 times per second and conversely reducing the pressure in the processing tank because the measured pressure is higher than the target pressure, the operation is performed to close the opening of the outside air intake valve 3 by 5 per second. is there. In this case, the gradient when the pressure value increases is steep, whereas the gradient when the pressure is decreased is gentle. If the amount of operation of the outside air intake valve is not weighted, the amount of operation of the outside air intake valve will be the same when opening and closing, but the amount of action in that case will be when opening the outside air intake valve. Appears larger and appears smaller when the outside air intake valve is closed. Therefore, the inclination is different, and the pressure in the treatment tank is greatly increased. As a result, the average pressure value is higher than the target value.

On the other hand, in FIG. 2 in which the operation amount of the outside air intake valve is weighted, the operation amount in the direction of opening the outside air intake valve is made smaller and the operation amount in the closing direction is made larger. Since the amount of operation of the outside air intake valve is weighted so that the inclination of the pressure value in the processing tank is the same between the open side and the close side of the outside air intake valve, a waveform close to a sine wave is drawn. The pressure value in the processing tank does not shift to one side with respect to the target value, and the average value is close to the target value. By doing in this way, it becomes possible to hold | maintain the pressure in a processing tank more precisely near target pressure, and can eliminate the excess and deficiency of cooling.

The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 Vacuum generator
2 treatment tank
3 Outside air intake valve 4 Outside air intake pipe 5 Pressure measuring device 6 Operation control device 7 Object to be cooled 8 Condensed water tank 9 Vacuum piping 10 Heat exchanger 11 Cold water generator

Claims (2)

It has a processing tank that contains the object to be cooled, a pressure measuring device that measures the pressure in the processing tank, and a vacuum generator that discharges the gas in the processing tank. A vacuum cooling device that cools an object to be cooled, and an outside air intake valve that takes in outside air is provided in order to adjust the pressure reducing capacity of the vacuum generator during cooling operation, and the opening degree of the outside air intake valve is operated. In the vacuum cooling device that adjusts the decompression capacity by
Aiming to maintain the pressure inside the treatment tank at the target pressure while the inside of the treatment tank is in a high vacuum, and when the measured pressure in the treatment tank is lower than the target pressure, an operation to open the opening of the outside air intake valve If the measured pressure in the treatment tank is higher than the target pressure, the operation of closing the opening of the outside air intake valve,
A vacuum cooling apparatus characterized by weighting the operation amount so that the operation amount of the outside air intake valve is moved small to the opening side and moved largely to the closing side. 2. The vacuum cooling device according to claim 1, wherein when the opening of the outside air intake valve is opened because the measured pressure in the processing tank is lower than the target pressure, the outside air intake valve is operated every predetermined time. When the operation for opening the outside air intake valve is performed by opening the amount A and the measured pressure in the processing tank is higher than the target pressure, the outside air intake valve is closed by the operation amount B every predetermined time. A vacuum cooling device for performing an operation, wherein an operation amount A when the outside air intake valve is opened is smaller than an operation amount B when the outside air intake valve is closed.

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