JP6983379B2 - Cold water production system - Google Patents

Description

The present invention relates to a cold water production system in which a secondary refrigerant such as brine is cooled by a primary refrigerant of a refrigerator and cold water is produced by the secondary refrigerant.

Conventionally, as disclosed in Patent Document 1 below, a cold water production system for cooling water using a refrigerator is known. Explaining with reference to FIG. 3 of the document, the cold water production system includes a heat exchanger (32) having a double pipe structure, and the heat exchanger (32) is a refrigerator (33) via a refrigerant circulation path (33). While connected to 31), it is connected to the cold water tank (34) via the cold water circulation passages (36, 37). In the heat exchanger (32), the refrigerant of the refrigerator (31) and the circulating water of the cold water tank (34) can be exchanged for heat to cool the stored water in the cold water tank (34).

In this type of cold water production system, the refrigerant and water are exchanged for heat in the heat exchanger. Therefore, if the heat exchanger is damaged, the refrigerant or oil of the refrigerator may be mixed in the cold water. Therefore, depending on the application of cold water (for example, when cold water is used for cooling food), in order to improve safety, a brine circulation path (2) is provided between the refrigerant circulation path (primary refrigerant circulation path) and the cold water circulation path. It is also conceivable to intervene the next refrigerant circulation path). That is, the brine is cooled by the refrigerator, and the water is cooled by the brine.

However, even when using brine, further safety measures are desired in case the heat exchanger between brine and water is damaged. That is, even if the heat exchanger between the brine and water should be damaged, it is preferable if the brine can be prevented from being mixed into the cold water. In particular, if the cooling operation is stopped (the refrigerator is stopped) and both the brine circulation and the cold water circulation are stopped, the pressure on both the brine side and the water side will be the same, and the heat exchanger will be damaged by any chance. Since there is a risk that brine will flow into the water side, countermeasures are desired.

Japanese Unexamined Patent Publication No. 9-166339 (paragraph 0002, FIG. 3)

The problem to be solved by the present invention is to ensure that the secondary refrigerant is mixed with the cold water in the system in which the secondary refrigerant such as brine is cooled by the primary refrigerant of the refrigerator and the cold water is produced by the secondary refrigerant. The purpose is to provide a cold water production system that can prevent and enhance safety.

The present invention has been made to solve the above problems, and the invention according to claim 1 makes it possible to cool the secondary refrigerant by heat exchange with the primary refrigerant of the refrigerator, and heats the secondary refrigerant. The cold water is provided with a refrigerant circulation path for circulating in the exchanger and a cold water circulation path in which water is circulated between the cold water tank and the heat exchanger and the circulating water can be cooled by the secondary refrigerant in the heat exchanger. cold water feed line to the heat exchanger from the tank, the circulation pump is provided, even during circulatory arrest of the secondary refrigerant in the refrigerant circulation path, the cold water is circulated to the cold water circulation passage by the circulation pump, wherein The cold water production system is characterized in that the circulation flow rate of the cold water circulation path while the circulation of the refrigerant circulation path is stopped is smaller than the circulation flow rate of the cold water circulation path during the circulation of the refrigerant circulation path.

According to the invention according to claim 1, the secondary refrigerant can be cooled by the primary refrigerant of the refrigerator, the circulating water can be cooled by the secondary refrigerant, and the stored water in the chilled water tank can be cooled. Then, even when the circulation of the secondary refrigerant in the refrigerant circulation path is stopped, cold water is circulated in the cold water circulation path by the circulation pump. Since the circulation pump is provided in the chilled water feed path from the chilled water tank to the heat exchanger, the pressure on the water side of the heat exchanger can be higher than the pressure on the secondary refrigerant side by the discharge pressure of the circulation pump. .. As a result, even if the heat exchanger is damaged, it is possible to prevent the secondary refrigerant from being mixed into the cold water and improve the safety.

According to the first aspect of the present invention, the circulation flow rate of the cold water while the circulation of the secondary refrigerant is stopped is smaller than the circulation flow rate of the cold water during the circulation of the secondary refrigerant. Therefore, even if the cold water circulation pump is operated while the cooling operation is stopped (the operation of the refrigerator is stopped), energy saving can be achieved.

According to the second aspect of the present invention, the first circulation pump and the second circulation pump having a smaller capacity are provided in parallel in the chilled water feeding path from the chilled water tank to the heat exchanger. While the first circulation pump is operating or the first circulation pump and the second circulation pump are operating, the circulation of the refrigerant circulation path is performed, and while the circulation of the refrigerant circulation path is stopped, the second circulation pump is performed. The cold water production system according to claim 1 , wherein the cold water production system is operated.

According to the second aspect of the present invention, by using a second circulation pump having a relatively small capacity, it is possible to easily prevent the secondary refrigerant from being mixed into the cold water with a simple configuration and improve the safety. At the same time, energy can be saved.

According to the third aspect of the present invention, the chilled water return path from the heat exchanger to the chilled water tank is provided with a flow path cross-sectional area adjusting mechanism, and the adjusting mechanism is provided while the circulation of the refrigerant circulation path is stopped. The cold water production system according to claim 1 or 2 , wherein the cross-sectional area of the flow path of the cold water return path is reduced accordingly.

According to the third aspect of the present invention, the pressure on the water side in the heat exchanger is reduced by reducing the cross-sectional area of the flow path of the chilled water return path from the heat exchanger to the chilled water tank while the circulation of the refrigerant circulation path is stopped. Can be enhanced. As a result, even if the heat exchanger is damaged, it is possible to more reliably prevent the secondary refrigerant from being mixed into the cold water, and further enhance the safety.

Further, in the invention according to claim 4 , the secondary refrigerant is brine, the refrigerant circulation path includes a brine tank for storing brine, and brine is provided between the brine tank and the heat exchanger. The cold water production system according to any one of claims 1 to 3 , characterized in that it is circulated.

According to the invention of claim 4 , brine can be used as a secondary refrigerant, and brine can be circulated between the brine tank and the heat exchanger.

According to the present invention, in a system in which a secondary refrigerant such as brine is cooled by a primary refrigerant of a refrigerator and cold water is produced by the secondary refrigerant, the secondary refrigerant is surely prevented from being mixed into the cold water. It can increase safety.

It is a schematic diagram which shows the cold water production system of one Example of this invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing a cold water production system 1 according to an embodiment of the present invention.

The cold water production system 1 of this embodiment is a system in which a secondary refrigerant is cooled by the primary refrigerant of the refrigerator 2 and cold water is produced by the secondary refrigerant. The secondary refrigerant is not particularly limited, but is typically brine. Hereinafter, the secondary refrigerant will be described as brine, but the same applies to other liquids.

As shown in FIG. 1, the cold water production system 1 of the present embodiment has a refrigerator 2 that circulates a primary refrigerant, a brine circulation path 3 that circulates brine as a secondary refrigerant, and a cold water circulation path 4 that circulates water. And prepare.

The brine circulation path 3 circulates brine between the brine tank 5 and the heat exchanger 6. The brine tank 5 is a tank that stores brine up to a set liquid level, and in this embodiment, the inside is open to atmospheric pressure. The heat exchanger 6 includes a flow path on the brine side and a flow path on the water side so that heat can be exchanged without mixing the brine and water. The heat exchanger 6 is not particularly limited in its configuration, but is, for example, a plate type heat exchanger.

Although the details will be described later, in the heat exchanger 6, the water is cooled by the brine to be cold water. When this cold water is used for cooling food (especially when it comes into direct contact with food), brine that is also acceptable as a food additive (for example, so as to be safe against leakage of brine due to damage to the heat exchanger 6). Propylene glycol) is preferably used.

The brine tank 5 and the heat exchanger 6 are connected by a brine feed path 7 and a brine return path 8. A brine pump 9 is provided in the brine feed path 7 (or the brine return path 8). When the brine pump 9 is operated, the brine in the brine tank 5 is sent to the heat exchanger 6 via the brine feed path 7 and returned to the brine tank 5 via the brine return path 8. Since the brine tank 5 is an open type tank as described above, the flow path on the brine side of the heat exchanger 6 is opened to a substantially atmospheric pressure while the brine pump 9 is stopped.

The brine in the brine circulation path 3 can be cooled by the refrigerator 2. In this embodiment, the brine in the brine tank 5 circulates with the refrigerator 2 and can be cooled. Specifically, the brine tank 5 is connected to the refrigerator 2 by a brine cooling outward path 10 and a brine cooling return path 11. A brine cooling pump 12 is provided on the brine cooling outward path 10 (or the brine cooling return path 11). When the brine cooling pump 12 is operated, the brine in the brine tank 5 is sent to the refrigerator 2 via the brine cooling outward path 10 and returned to the brine tank 5 via the brine cooling return path 11.

The refrigerator 2 is a steam compression type refrigerator in this embodiment. In this case, the refrigerator 2 is configured by sequentially connecting a compressor, a condenser, an expansion valve and an evaporator in an annular shape. The compressor compresses the refrigerant into a high-temperature, high-pressure gas. The condenser liquefies the refrigerant from the compressor. The expansion valve allows the refrigerant from the condenser to pass through to reduce the pressure and temperature of the refrigerant. The evaporator then evaporates the refrigerant from the expansion valve. The heat of vaporization during evaporation can be used to cool the brine. That is, the evaporator is a heat exchanger between the brine from the brine tank 5 and the refrigerant of the refrigerator 2.

The cold water circulation path 4 circulates water between the cold water tank 13 and the heat exchanger 6. The cold water tank 13 is a tank that stores water up to a set water level, and in this embodiment, the inside is open to atmospheric pressure. As described above, the heat exchanger 6 is configured to be heat exchangeable without mixing brine and water.

The cold water tank 13 and the heat exchanger 6 are connected by a cold water feed path 14 and a cold water return path 15. A first circulation pump 16 and a second circulation pump 17 are provided in parallel in the chilled water feed path 14 from the chilled water tank 13 to the heat exchanger 6. Specifically, the chilled water feed path 14 from the chilled water tank 13 branches into the first chilled water feed path 14a and the second chilled water feed path 14b, then merges again and is connected to the heat exchanger 6. The first chilled water feed path 14a is provided with the first circulation pump 16, while the second chilled water feed path 14b is provided with the second circulation pump 17.

The second circulation pump 17 is a pump having a smaller capacity than the first circulation pump 16. That is, when the first circulation pump 16 is operated, cold water can flow at a larger flow rate than the second circulation pump 17, while when the second circulation pump 17 is operated, the flow rate is smaller than that of the first circulation pump 16. Cold water can flow.

If desired, the cold water in the cold water tank 13 can be supplied to a cold water demand point (for example, a food machine) via the cold water take-out passage 18. In the case of the illustrated example, the cold water take-out passage 18 is provided with a water supply pump 20 in addition to the manual sluice valve 19. The sluice valve 19 is normally kept open. Therefore, by operating the water supply pump 20 in response to the request of the cold water demand location, the cold water in the cold water tank 13 can be sent to the cold water demand location. The cold water tank 13 can be appropriately supplied with water via a ball tap 21 or the like, and the water level in the cold water tank 13 is maintained as desired. By the way, the cold water in the cold water tank 13 can be used for cooling food, for example, and the cold water itself can also be used as a beverage or food.

The cold water production system 1 includes a brine temperature sensor 22 for detecting the temperature of the brine and a cold water temperature sensor 23 for detecting the temperature of the cold water. Although the brine temperature sensor 22 is provided in the brine tank 5 in the illustrated example, the brine temperature sensor 22 may be provided in the brine feed path 7, the brine return path 8, the brine cooling outward path 10, or the brine cooling return path 11 as the case may be. Further, although the chilled water temperature sensor 23 is provided in the chilled water tank 13 in the illustrated example, it may be provided in the chilled water feed path 14 or the chilled water return path 15 as the case may be.

Next, an operation example of the cold water production system 1 of this embodiment will be described. The operation described below is automatically performed by a controller (not shown). That is, the controller is connected to the refrigerator 2, the brine pump 9, the brine cooling pump 12, the first circulation pump 16, the second circulation pump 17, the brine temperature sensor 22, the chilled water temperature sensor 23, and the like. The refrigerator 2 and the pumps 9, 12, 16, 17 and the like are controlled based on the detection signals of the sensors 22 and 23.

When the start of operation is instructed, such as when the start button is pressed, the controller starts the operation of the cold water production system 1. On the other hand, when the operation stop is instructed, such as when the stop button is pressed, the controller stops the operation of the cold water production system 1.

During the operation of the cold water production system 1, the brine is cooled so as to maintain the detection temperature of the brine temperature sensor 22 at a set temperature (for example, -3 ° C.). Specifically, by operating the brine cooling pump 12 while the refrigerator 2 is operating, the brine in the brine tank 5 is circulated to the refrigerator 2 to cool and maintain the brine at a set temperature. .. At this time, if the detection temperature of the brine temperature sensor 22 is equal to or higher than the set upper limit value, the refrigerator 2 and the brine cooling pump 12 are operated, while if the detection temperature is equal to or lower than the set lower limit value, the refrigerator 2 and the brine cooling pump 12 are stopped. You may let me.

During the operation of the cold water production system 1, the cold water is cooled so as to maintain the detection temperature of the cold water temperature sensor 23 at a target temperature (for example, 1.5 ° C to 3 ° C). Specifically, if the detection temperature of the chilled water temperature sensor 23 is the upper limit temperature (for example, 3 ° C.) or higher, the brine is in a state where the first circulation pump 16 (or the first circulation pump 16 and the second circulation pump 17) are operated. Operate the pump 9. As a result, the water in the cold water tank 13 circulates with the heat exchanger 6, and the brine in the brine tank 5 circulates with the heat exchanger 6. Therefore, in the heat exchanger 6, the circulating water (and thus the water in the cold water tank 13) is cooled by the brine.

While both water and brine are circulating in the heat exchanger 6, it is preferable to maintain the circulation pressure on the water side at a pressure higher than the circulation pressure on the brine side. That is, during the operation of the first circulation pump 16 (or the first circulation pump 16 and the second circulation pump 17) and the brine pump 9, the pressure on the water side in the heat exchanger 6 is higher than the pressure on the brine side. , Each pump 9, 16 (17) and piping are installed and the flow rate is set. As a result, even if the heat exchanger 6 is damaged, it is possible to prevent the brine from entering the cold water circulation path 4 (and by extension, the cold water tank 13 and the cold water demanding point), and improve safety.

On the other hand, when the detection temperature of the chilled water temperature sensor 23 becomes equal to or lower than the lower limit temperature (a temperature lower than the upper limit temperature, for example, 1.5 ° C.), the second circulation pump 17 is operated with the brine pump 9 stopped. Let me. At this time, it is preferable to stop the first circulation pump 16.

As described above, in the cold water production system 1 of the present embodiment, cold water is circulated to the cold water circulation path 4 by the second circulation pump 17 even when the circulation of the brine in the brine circulation path 3 is stopped. Since the second circulation pump 17 is provided in the chilled water feed path 14 from the chilled water tank 13 to the heat exchanger 6, the pressure on the water side in the heat exchanger 6 is brought to the brine side by the discharge pressure of the second circulation pump 17. Can be higher than the pressure of. As a result, even if the heat exchanger 6 is damaged, it is possible to prevent the brine from entering the cold water circulation path 4 (and by extension, the cold water tank 13 and the cold water demanding point), and improve safety. Moreover, the second circulation pump 17 operated while the circulation of the brine circulation path 3 is stopped has a smaller capacity than the first circulation pump 16 operated during the circulation of the brine circulation path 3, so that energy can be saved. can. It is sufficient for the second circulation pump 17 to be able to circulate cold water in the cold water circulation path 4, and the smaller the capacity, the more energy can be saved.

When the operation of the cold water production system 1 is stopped, the refrigerator 2, the brine pump 9, the brine cooling pump 12, and the first circulation pump 16 are stopped, but the operation of the second circulation pump 17 is continued. As a result, the pressure on the water side of the heat exchanger 6 can be made higher than the pressure on the brine side. Therefore, even if the heat exchanger 6 is damaged, it is possible to prevent the brine from being mixed into the cold water circulation path 4 (and by extension, the cold water tank 13 and the cold water demanding point), and improve safety. Moreover, since the second circulation pump 17 has a smaller capacity than the first circulation pump 16, energy can be saved.

As described above, according to the cold water production system 1 of the present embodiment, the brine pump 9 and the first circulation pump 16 are operated during the circulation of the brine circulation path 3, but the pressure on the water side in the heat exchanger 6 is operated. By increasing the pressure above the pressure on the brine side, even if the heat exchanger 6 is damaged, it is possible to prevent the brine from entering the cold water circulation path 4. Further, the first circulation pump 16 is stopped while the circulation of the brine circulation path 3 is stopped (in other words, the operation of the cold water production system 1 is stopped, or even during the operation, the cooling operation of the cold water by the brine is temporarily stopped). By operating the second circulation pump 17 in this state to raise the pressure on the water side of the heat exchanger 6 higher than the pressure on the brine side, even if the heat exchanger 6 is damaged, it goes to the cold water circulation path 4. It is possible to prevent the mixing of brine. In this way, regardless of the operating condition, the pressure on the water side is always higher than the pressure on the brine side, and even if the heat exchanger 6 is damaged, the brine is surely prevented from being mixed into the cold water. Can be done. Therefore, for example, even when the operation is stopped at night, the pressure on the water side can be constantly increased to prevent adverse effects due to damage to the heat exchanger 6. Moreover, energy saving can be achieved by using the second circulation pump 17 having a relatively small capacity.

By the way, it is preferable to provide a flow path cross-sectional area adjusting mechanism (not shown) in the chilled water return path 15 from the heat exchanger 6 to the chilled water tank 13. As the flow path cross-sectional area adjusting mechanism, a valve whose opening degree can be adjusted (for example, a motor valve) can be used. Alternatively, a small-diameter sub-flow path may be provided in parallel in a part of the main flow path of the cold water return path 15, and the opening and closing of the valve provided in each of these flow paths may be switched. In any case, while the circulation of the brine circulation path 3 is stopped due to the stop of the brine pump 9, the adjustment mechanism reduces the cross-sectional area of the flow path of the cold water return path 15. As a result, the pressure on the water side of the heat exchanger 6 can be increased, and even if the heat exchanger 6 is damaged, the contamination of brine into the cold water can be prevented more reliably, and the safety can be further enhanced. Can be done.

The cold water production system 1 of the present invention is not limited to the configuration of the above embodiment, and can be appropriately modified. In particular, (a) a refrigerant circulation path 3 in which the secondary refrigerant can be cooled by heat exchange with the primary refrigerant of the refrigerator 2 and the secondary refrigerant is circulated to the heat exchanger 6, and (b) a cold water tank 13. It is provided with a chilled water circulation path 4 capable of circulating water with and from the heat exchanger 6 and cooling the circulating water with a secondary refrigerant in the heat exchanger 6, and (c) cold water from the chilled water tank 13 to the heat exchanger 6. A circulation pump 17 is provided in the feed path 14, and other configurations are appropriate as long as the circulation pump 17 circulates cold water in the cold water circulation path 4 even when the circulation of the secondary refrigerant in the refrigerant circulation path 3 is stopped. Can be changed to. Further, the circulation flow rate of the chilled water circulation path 4 while the circulation of the refrigerant circulation path 3 is stopped is preferably smaller than the circulation flow rate of the chilled water circulation path 4 during the circulation of the refrigerant circulation path 3. The means can be changed as appropriate.

For example, in the above embodiment, the inside of the cold water tank 13 is opened under atmospheric pressure, and when the cold water circulation pumps 16 and 17 are stopped, the cold water circulation path 4 and the heat exchanger 6 (water side) are opened under atmospheric pressure. The cold water circulation path 4 and the heat exchanger 6 may be held at a pressure exceeding the atmospheric pressure. In that case, an on-off valve is provided at the entrance / exit of the cold water tank 13 (cold water feed path 14 (downstream from the confluence of the first cold water feed path 14a and the second cold water feed path 14b), cold water return path 15). While the circulation of the brine in the brine circulation path 3 is stopped, the water-side flow path of the heat exchanger 6 is maintained in a pressurized state. Specifically, when stopping the circulation of the brine in the brine circulation path 3, first, after closing the on-off valve of the cold water return path 15, the water side flow path of the heat exchanger 6 is passed through the first circulation pump 16 (and / /. Alternatively, the on-off valve of the cold water feed path 14 may be closed and the circulation pump 16 (17) may be stopped while being pressurized by the second circulation pump 17). As a result, even when the circulation pumps 16 and 17 are stopped, the pressure on the water side of the heat exchanger 6 can be maintained higher than the pressure on the brine side. Then, in the unlikely event that the pressure in the cold water circulation passage 4 becomes lower than a predetermined value, the on-off valve may be opened to operate the second circulation pump 17.

Further, in the above embodiment, the first circulation pump 16 and the second circulation pump 17 are provided in parallel in the cold water circulation passage 4, and among the circulation pumps 16 and 17, depending on the start and stop of the brine pump 9. It was switched between operating only the first circulation pump 16 (or both the first circulation pump 16 and the second circulation pump 17) or operating only the second circulation pump 17, but even if the configuration is as follows. good. That is, only one circulation pump 16 is provided in the cold water feed path 14 from the cold water tank 13 to the heat exchanger 6 (installation of the second cold water feed path 14b and the second circulation pump 17 is omitted), and this circulation. The rotation speed of the pump 16 may be controlled (inverter control). In this case, while the brine pump 9 is stopped, the rotation speed of the cold water circulation pump 16 may be lowered to a predetermined level.

Further, in the above embodiment, the brine is circulated between the brine tank 5 and the refrigerator 2 in order to cool the brine, but it may be configured as follows. That is, the evaporator of the refrigerator 2 may be provided in the brine tank 5, or may be provided in the brine feed path 7. In this case, when the refrigerator 2 is operated, the refrigerant (primary refrigerant) of the refrigerator 2 is supplied to the evaporator and exchanges heat with the brine in the brine tank 5 or the brine feed path 7 to cool the brine.

In addition, the cold water production system 1 can be used not only to cool water to produce cold water, but also to cool a beverage to a low temperature, for example.

1 Cold water production system 2 Refrigerator 3 Brine circulation route 4 Cold water circulation route 5 Brine tank 6 Heat exchanger 7 Brine feed route 8 Brine return route 9 Brine pump 10 Brine cooling outbound route 11 Brine cooling return route 12 Brine cooling pump 13 Cold water tank 14 Cold water Feed path (14a: first cold water feed path, 14b: second cold water feed path)
15 Cold water return path 16 1st circulation pump 17 2nd circulation pump 18 Cold water take-out path 19 Gate valve 20 Water supply pump 21 Ball tap 22 Brine temperature sensor 23 Cold water temperature sensor

Claims (4)

A refrigerant circulation path that allows the secondary refrigerant to be cooled by heat exchange with the primary refrigerant of the refrigerator and circulates the secondary refrigerant to the heat exchanger.
A cold water circulation path is provided in which water is circulated between the cold water tank and the heat exchanger, and the circulating water can be cooled by the secondary refrigerant in the heat exchanger.
A circulation pump is provided in the cold water feed path from the cold water tank to the heat exchanger, and the circulation pump circulates cold water in the cold water circulation path even when the circulation of the secondary refrigerant in the refrigerant circulation path is stopped. ,
A cold water production system characterized in that the circulation flow rate of the cold water circulation path while the circulation of the refrigerant circulation path is stopped is smaller than the circulation flow rate of the cold water circulation path during circulation of the refrigerant circulation path. A first circulation pump and a second circulation pump having a smaller capacity are provided in parallel in the chilled water feed path from the chilled water tank to the heat exchanger.
While the first circulation pump is operating or the first circulation pump and the second circulation pump are operating, the refrigerant circulation path is circulated, and the second circulation is stopped while the circulation of the refrigerant circulation path is stopped. The cold water production system according to claim 1 , wherein the pump is operated. The chilled water return path from the heat exchanger to the chilled water tank is provided with a flow path cross-sectional area adjustment mechanism.
The cold water production system according to claim 1 or 2 , wherein the flow path cross-sectional area of the cold water return path is reduced by the adjustment mechanism while the circulation of the refrigerant circulation path is stopped. The secondary refrigerant is brine,
The cold water according to any one of claims 1 to 3 , wherein the refrigerant circulation path includes a brine tank for storing brine, and the brine is circulated between the brine tank and the heat exchanger. Manufacturing system.

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