JP3922156B2 - Control method of vacuum cooling device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control method and a vacuum cooling device for a vacuum cooling device that evaporates moisture of an object to be cooled under reduced pressure and cools it using latent heat of vaporization at that time.
[0002]
[Prior art]
As is well known, the vacuum cooling device sucks and cools the cooling tank containing the object to be cooled to lower the saturated vapor temperature and evaporate the water in the object to be cooled. The object to be cooled is cooled using the latent heat of vaporization. For example, in the food industry, this vacuum cooling device is used in a process of cooling cooked food.
[0003]
As the vacuum cooling device, various devices for reducing the pressure in the cooling tank (vacuum suction) have been proposed and put to practical use. For example, there is a type in which a first stage pressure reduction operation is performed by a steam ejector, and then most of the water vapor is condensed by a heat exchanger, and a second stage pressure reduction operation is performed by a vacuum pump to suck air and water vapor. In this case, a large amount of cooling water for condensing water vapor with the heat exchanger was necessary. (For example, see Patent Document 1.)
[0004]
[Patent Document 1]
Patent No. 3077602 gazette
[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 of the vacuum cooling device.
[0006]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-mentioned problems, and the invention according to claim 1 is that a steam ejector 4 is connected to a cooling tank 2 that accommodates an object to be cooled, and the exhaust of the steam ejector 4 is exhausted. A method for controlling a vacuum cooling device 1 in which a vacuum pump 7 is connected to a side 5 via a heat exchanger 6 , wherein the vacuum pump 7 is operated without operating the steam ejector 4, and the heat exchanger 6 is characterized in that a step of decreasing the supply amount of the cooling water for 6 is performed, and thereafter, the step of operating the steam ejector 4 and the vacuum pump 7 and increasing the supply amount is performed .
[0007]
The invention described in claim 2 is characterized in that, in claim 1, the step of reducing the supply amount of the cooling water is a slow cooling step .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described. This embodiment can be implemented in a vacuum cooling process in which food or the like (hereinafter referred to as “object to be cooled”) is cooled using a decompression means. First, a vacuum cooling device applied to the implementation of the present invention will be described.
[0010]
The vacuum cooling device includes a cooling tank that accommodates the object to be cooled, a steam ejector connected to an exhaust line of the cooling tank, a heat exchanger connected to an exhaust side of the steam ejector, and the heat exchanger And a controller for controlling the supply amount of the cooling water for the heat exchanger, and a controller for controlling the operation of the vacuum cooling device. That is, the vacuum cooling device includes two decompression means (the steam ejector and the vacuum pump) for decompressing the inside of the cooling tank.
[0011]
The cooling tank is formed in a size that accommodates the object to be cooled, and includes a door that seals the cooling tank, a return pressure line that returns the pressure in the cooling tank to atmospheric pressure, and the exhaust line. ing.
[0012]
The steam ejector performs a pressure reducing function by steam supplied from a steam line. The steam ejector is configured to depressurize the inside of the cooling tank using the exhaust line as a negative pressure, that is, perform a first-stage depressurization operation. That is, the steam ejector mixes the air in the cooling tank and the water vapor evaporated from the object to be cooled and the steam supplied to the steam ejector, and this mixed fluid (hereinafter referred to as “mixed fluid”). ). The mixed fluid is configured to flow into the heat exchanger.
[0013]
The heat exchanger condenses water vapor in the mixed fluid. The heat exchanger includes a cooling water line, and includes heat exchanging means, for example, a coil, communicating with the cooling water line. Since the saturated vapor temperature of the mixed fluid is considerably higher than that of the cooling water flowing in the coil, the water vapor is condensed on the surface of the coil, so that the partial pressure of the water vapor in the mixed fluid is reduced and the air is correspondingly reduced. The partial pressure of increases. That is, the heat exchanger increases the proportion of air in the mixed fluid.
[0014]
The vacuum pump is, for example, a positive displacement vacuum pump, a liquid ring vacuum pump, or the like, and the mixed fluid in which air occupies a main portion by the heat exchanger is sucked and exhausted by the vacuum pump. That is, the vacuum pump is configured to perform a second-stage pressure reducing operation.
[0015]
The control means is provided in the cooling water line, and is configured to control the supply amount of cooling water by combining, for example, a flow rate adjusting valve, a plurality of electromagnetic valves, an orifice, and the like.
[0016]
Here, it is also preferable that the control means controls the supply amount of the cooling water by controlling the supply pressure of the cooling water and the rotation speed of the water supply pump.
[0017]
The operation of the vacuum cooling apparatus having such a configuration will be described. First, the object to be cooled is accommodated in the cooling tank, the door is closed, and the cooling tank is sealed. And the said steam ejector and the said vacuum pump are operated, the inside of the said cooling tank is pressure-reduced, and the said to-be-cooled object is cooled. At this time, the heat exchanger condenses the water vapor in the mixed fluid to increase the proportion of the air in the mixed fluid so that the vacuum pump can efficiently suck the air. And if the temperature of the said to-be-cooled object falls, the inside of the said cooling tank will be decompressed and a cooling process will be complete | finished.
[0018]
Next, a method for controlling the vacuum cooling device will be described. First, the control method of the first embodiment will be described.
[0019]
The object to be cooled is accommodated in the cooling tank and the operation is started. Immediately after the start of the operation of the vacuum cooling device, the pressure in the cooling tank is close to atmospheric pressure, so it is easy to reduce the pressure, and the heat exchange capability during operation of the heat exchanger may be small. Therefore, the cooling water supply amount is reduced and supplied to the heat exchanger. And when a cooling process progresses and it further reduces pressure, it controls so that the supply amount of cooling water is increased and the heat exchange capability at the time of the operation of the heat exchanger is increased. That is, the amount of cooling water supplied to the heat exchanger is controlled in accordance with the operating status of the vacuum cooling device. Next, when the temperature of the object to be cooled decreases and the inside of the cooling tank is restored, the supply of cooling water is stopped. Thereby, the usage-amount of the cooling water in a cooling process can be reduced.
[0020]
Here, as a modification of the first embodiment, it is also preferable to control the amount of cooling water supplied to the heat exchanger according to the type of the object to be cooled. That is, when the cooling object is of a type that does not hinder even if the condensation capacity of the heat exchanger is reduced, the supply amount of the cooling water is controlled to be reduced. Thereby, the usage-amount of the cooling water in a cooling process can be reduced.
[0021]
Next, a second embodiment will be described. This second embodiment can be suitably implemented in the method for controlling the vacuum cooling apparatus, particularly when cooling the food containing a large amount of water, for example, a soup, contained in the object to be cooled. That is, it is effective when performing a so-called slow cooling process in which the inside of the cooling tank is slowly decompressed during the operation of the vacuum cooling device.
[0022]
The slow cooling step is a step of preventing bumping or the like due to sudden reduction in pressure of the object to be cooled. Therefore, during this slow cooling step, the heat exchanger capacity of the heat exchanger may be small, so that the amount of cooling water supplied is reduced. In the slow cooling step, only the vacuum pump is operated, and the steam ejector is not operated. When the cooling process proceeds and the pressure is further reduced, the steam ejector is operated, and the supply amount of cooling water is increased to control the heat exchanging capacity when the heat exchanger is activated. Next, when the temperature of the object to be cooled decreases and the inside of the cooling tank is restored, the supply of cooling water is stopped. Thereby, the usage-amount of the cooling water in the said slow cooling process can be reduced.
[0023]
Here, as a modification of the second embodiment, when the steam ejector is operated, the supply of steam to the steam ejector and the supply of cooling water to the heat exchanger are performed in multiple stages. It is also preferable to carry out proportionally.
[0024]
As described above, according to these embodiments, the amount of cooling water used in the heat exchanger of the vacuum cooling device can be reduced.
[0025]
【Example】
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. This embodiment can be implemented in a vacuum cooling process in which food or the like (hereinafter referred to as “object to be cooled”) is cooled using a decompression means. First, a vacuum cooling device applied to the implementation of the present invention will be described. FIG. 1 is a schematic explanatory view illustrating the vacuum cooling device.
[0026]
In FIG. 1, a vacuum cooling device 1 includes a cooling tank 2 that accommodates an object to be cooled (not shown), a steam ejector 4 connected to an exhaust line 3 of the cooling tank 2, and an exhaust side 5 of the steam ejector 4. A heat exchanger 6 connected to the heat exchanger 6, a vacuum pump 7 connected to the downstream side of the heat exchanger 6, a control means 8 for controlling a supply amount of cooling water for the heat exchanger 6, and the vacuum cooling It comprises a controller (not shown) that controls the operation of the device 1. That is, the vacuum cooling device 1 includes the steam ejector 4 and the vacuum pump 7 in order to depressurize the cooling tank 2.
[0027]
The cooling tank 2 is sized to accommodate the object to be cooled, and includes a door (not shown) for sealing the cooling tank 2 and a return pressure line 9 for returning the pressure in the cooling tank 2 to atmospheric pressure. And the exhaust line 3. The return pressure line 9 is provided with a filter 10 for cleaning air and an air introduction control valve 11.
[0028]
The steam ejector 4 decompresses the inside of the cooling tank 2 with steam supplied from a steam line 12. The steam line 12 is connected to a steam inlet 13 of the steam ejector 4, and a steam control valve 14 is provided in the steam line 12. The steam line 12 is connected to a boiler (not shown). The suction port 15 of the steam ejector 4 is connected to the exhaust line 3. More specifically, by supplying steam from the steam inlet 13 to the steam ejector 4, the inside of the cooling tank 2 is depressurized with the exhaust line 3 as a negative pressure, that is, the first-stage depressurization is performed. The steam ejector 4 mixes the air in the cooling tank 2 and the water vapor evaporated from the object to be cooled and the steam supplied to the steam ejector 4, and this mixed fluid (hereinafter referred to as “mixed fluid”). .) Is discharged. Then, the mixed fluid flows into the heat exchanger 6.
[0029]
The heat exchanger 6 condenses pressurized water vapor in the mixed fluid, and is connected to a cooling water line 16. The heat exchanger 6 includes a coil 17 which is a heat exchanging means and a cooling water drain line 18 and a mixed fluid discharge line 19. Since the saturated vapor temperature of the mixed fluid is considerably higher than that of the cooling water flowing in the coil 17, it is condensed on the surface of the coil. Therefore, the partial pressure of water vapor in the mixed fluid decreases, and the partial pressure of air increases accordingly. That is, the heat exchanger 6 increases the proportion of air in the mixed fluid.
[0030]
The vacuum pump 7 is connected to the heat exchanger 6 through the mixed fluid discharge line 19. The mixed fluid discharge line 19 is provided with a check valve 20. The vacuum pump 7 is a water-sealed vacuum pump, is connected to a sealed water line 22 branched from a water supply line 21, and includes a discharge line 23 for discharging sealed water and the mixed fluid. Therefore, the vacuum pump 7 performs an operation of sucking and exhausting the mixed fluid whose proportion of air is increased by the heat exchanger 6, that is, a second-stage decompression operation.
[0031]
The control means 8 includes a first electromagnetic valve 24 that controls water supply, a second electromagnetic valve 25 that similarly controls water supply, a first orifice 26 that restricts the flow rate, and a second orifice 27 that similarly restricts the flow rate. It is comprised by. The first electromagnetic valve 24 and the first orifice 26 are connected in series and are provided in a first cooling water line 28 branched from the water supply line 21. The second solenoid valve 25 and the second orifice 27 are connected in series and are provided in a second cooling water line 29 branched from the water supply line 21. That is, both the cooling water lines 28 and 29 are arranged in parallel, and merge with the cooling water line 16 at a junction 30 on the downstream side of the orifices 26 and 27, respectively.
[0032]
The controller (not shown) is connected to the air introduction control valve 11, the steam control valve 14, the vacuum pump 7, and both the electromagnetic valves 24 and 25 via lines (not shown), respectively. The control part (illustration omitted) programmed so that each operation | movement may be controlled is provided. The controller controls the operation of the vacuum cooling device 1.
[0033]
The operation of the vacuum cooling device 1 having such a configuration will be described. First, the object to be cooled is accommodated in the cooling tank 2, the door is closed, and the cooling tank 2 is sealed. And the said steam ejector 4 and the said vacuum pump 7 are operated, the inside of the said cooling tank 2 is pressure-reduced, and the said to-be-cooled object is cooled. At this time, cooling water is supplied from the cooling water line 16, the water vapor in the mixed fluid is condensed on the surface of the coil 17 by the heat exchanger 6, and the ratio of air in the mixed fluid is increased. The vacuum pump 7 can suck air efficiently. And if the temperature of the said to-be-cooled object falls, the inside of the said cooling tank 2 will be decompressed and a cooling process will be complete | finished.
[0034]
Next, a first embodiment of the control method of the vacuum cooling device 1 having the above-described configuration will be described.
[0035]
When the vacuum cooling device 1 is operated, both the steam ejector 4 and the vacuum pump 7 are operated. In this case, immediately after the operation of the vacuum cooling device 1 is started, the pressure in the cooling tank 2 is close to atmospheric pressure, so it is easy to reduce the pressure, and the heat exchanging capacity when the heat exchanger 6 is operated is small. It's okay. Therefore, since the supply amount of the cooling water may be small, only the first electromagnetic valve 24 is opened.
[0036]
When the cooling process proceeds and the pressure is further reduced, the second electromagnetic valve 25 is also opened, that is, both the electromagnetic valves 24 and 25 are opened to increase the supply amount of cooling water, and the heat exchanger 6 Control to increase heat exchange capacity during operation.
[0037]
Next, when the pressure in the cooling tank 2 is restored, both the steam ejector 4 and the vacuum pump 7 are stopped, both the electromagnetic valves 24 and 25 are closed, and the supply of cooling water is stopped. Then, the air introduction control valve 11 is opened to restore the pressure. Thereby, the usage-amount of the cooling water by the initial driving | operation in a cooling process can be reduced.
[0038]
Next, a second embodiment will be described. This second embodiment is a modification of the first embodiment, and is a control method for performing a slow cooling step of slowly depressurizing the inside of the cooling tank 2 during the vacuum cooling process. The control method of the second embodiment will be described with reference to FIG.
[0039]
The slow cooling step is a step of preventing bumping or the like due to sudden reduction in pressure of the object to be cooled. In FIG. 1, during the slow cooling process, the controller operates only the vacuum pump 7 and does not operate the steam ejector 4. That is, steam is not supplied to the steam ejector 4 during the slow cooling step. Thereby, the heat exchanger 6 does not need to cool the heat quantity of the steam, only the heat quantity discharged from the cooling tank 2 may be cooled, and the heat exchange capacity of the heat exchanger 6 may be small. Become. Therefore, since the supply amount of the cooling water may be small, only the first electromagnetic valve 24 is opened.
[0040]
When the cooling process proceeds and the pressure is further reduced, the steam control valve 14 is opened to operate the steam ejector 4, and both the solenoid valves 24 and 25 are opened to increase the supply amount of cooling water. The heat exchanger 6 is controlled so as to increase the heat exchange capacity when the heat exchanger 6 is operated.
[0041]
Next, when the pressure in the cooling tank 2 is restored, both the steam ejector 4 and the vacuum pump 7 are stopped, both the electromagnetic valves 24 and 25 are closed, and the supply of cooling water is stopped. Then, the air introduction control valve 11 is opened to restore the pressure. Thereby, the usage-amount of the cooling water in a slow cooling process can be reduced.
【The invention's effect】
As mentioned above, according to this invention, the usage-amount of the cooling water in the heat exchanger of a vacuum cooling device can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view for explaining a vacuum cooling device of a first embodiment to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum cooling device 2 Cooling tank 4 Steam ejector 5 Exhaust side 6 Heat exchanger 7 Vacuum pump 8 Control means

Claims (2)

A control method of the vacuum cooling device 1 in which a steam ejector 4 is connected to a cooling tank 2 that accommodates an object to be cooled, and a vacuum pump 7 is connected to an exhaust side 5 of the steam ejector 4 via a heat exchanger 6, The steam ejector 4 is not operated, the vacuum pump 7 is operated, and the supply amount of the cooling water for the heat exchanger 6 is reduced, and then the steam ejector 4 and the vacuum pump 7 are turned on. A method for controlling a vacuum cooling apparatus , comprising: operating and increasing the supply amount . The method for controlling a vacuum cooling apparatus according to claim 1, wherein the step of reducing the supply amount of the cooling water is a slow cooling step .

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