JP2021046986A - Cold water manufacturing system - Google Patents

Abstract

To provide a cold water manufacturing system capable of cooling water down to a target temperature while preventing the freezing of the water in a heat exchanger.SOLUTION: A cold water manufacturing system 1 includes a brine tank 2 for storing brine, a chiller 3 for chilling the brine from the brine tank 2, and a heat exchanger 4 for making a heat exchange with the brine chilled by the chiller 3 to cool water. The cold water manufacturing system 1 further includes brine flow regulating means (a brine valve 12) for regulating the flow of the brine passing through the heat exchanger 4, and control means for controlling the brine flow regulating means on the basis of the outlet side water temperature of the heat exchanger 4. The control means controls the brine flow regulating means to set the outlet side water temperature to be [target temperature+set value] while supplying the brine to the heat exchanger 4 within a range not lower than a preset lower limit flow amount.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cold water production system in which cold water is produced by cooling water with brine cooled by a chiller.

Conventionally, as disclosed in Patent Document 1 below, (i) a refrigerator or a heat pump, (ii) a heat exchanger between brine and cold water, and (iii) a brine pipe connecting both, a brine circulation pump, and a brine. A chilled water production system including equipment having a tank and (iv) chilled water piping connected to a heat exchanger, a chilled water supply pump, and equipment having a chilled water tank is known. According to this system, the brine can be cooled by a chiller (refrigerator or the like), and the brine cools the water in the heat exchanger to produce cold water.

When producing cold water at a relatively low temperature (for example, 2.5 ° C. or lower) using this type of cold water production system, it is necessary to produce cold water at a desired temperature while preventing water from freezing in the heat exchanger. For example, it is conceivable to provide a flow rate adjusting valve in the brine pipe and adjust the opening degree of the valve (in other words, the flow rate of brine supplied to the heat exchanger) based on the water temperature on the outlet side of the heat exchanger.

However, for example, when it is desired to take out the water temperature on the outlet side of the heat exchanger at 1 ° C., if the valve is controlled aiming at the target value of 1 ° C., a certain control range with respect to the target value is generated. May freeze. If a temperature higher than the target temperature (for example, 1 ° C.) (for example, 1.5 ° C.) is set and controlled in an attempt to prevent this, the water temperature on the outlet side of the heat exchanger cannot be lowered to the target temperature.

Japanese Patent Application Laid-Open No. 4-143570 (Claims)

An object to be solved by the present invention is to provide a cold water production system capable of cooling water to a target temperature while preventing water from freezing in a heat exchanger.

The present invention has been made to solve the above problems, and the invention according to claim 1 has a brine tank for storing brine, a chiller for cooling the brine from the brine tank, and the chiller for cooling. In a cold water production system including a heat exchanger that cools water by heat exchange with the brine, the brine flow rate adjusting means for adjusting the flow rate of the brine passing through the heat exchanger and the water temperature on the outlet side of the heat exchanger are used. The control means includes a control means for controlling the brine flow rate adjusting means, and the control means sets the outlet side water temperature to "target temperature + setting" while supplying brine to the heat exchanger within a range not lower than a preset lower limit flow rate. It is a cold water production system characterized by controlling the brine flow rate adjusting means so as to have a value.

According to the invention of claim 1, in a cold water production system in which water is cooled by a heat exchanger with brine cooled by a chiller to produce cold water, the brine flow rate adjusting means is controlled based on the water temperature on the outlet side of the heat exchanger. Then, the flow rate of brine passing through the heat exchanger can be adjusted. By adjusting the brine flow rate while monitoring the water temperature on the outlet side of the heat exchanger, it is possible to produce cold water at a desired temperature while preventing the water in the heat exchanger from freezing. At that time, by controlling the brine flow rate adjusting means so that the water temperature on the outlet side of the heat exchanger is not the target temperature but a temperature higher than the target temperature, heat exchange is performed even if the target temperature is around 0 ° C. It is possible to prevent the water from freezing in the vessel. On the other hand, by supplying brine to the heat exchanger within a range that does not fall below the preset lower limit flow rate, it is possible to keep the brine flowing through the heat exchanger as needed, and to cool the water to the target temperature. Can be done.

In the invention according to claim 2, the brine supply path from the chiller to the heat exchanger and the brine discharge path from the heat exchanger to the brine tank are connected by a bypass path, and the brine flow rate. The adjusting means is a brine valve that adjusts the distribution ratio of returning the brine from the chiller to the brine tank via the heat exchanger or returning to the brine tank via the bypass path. The cold water production system according to claim 1.

According to the invention of claim 2, the brine supply path and the brine discharge path for the heat exchanger are connected by a bypass path, and the brine from the chiller is heat-exchanged by the brine valve as the brine flow rate adjusting means. It is possible to adjust the distribution ratio of returning to the brine tank via the vessel or returning to the brine tank via the bypass path. With such distribution control, it is possible to accurately adjust the flow rate of brine passing through the heat exchanger while maintaining the amount of brine circulating to the chiller, so cold water at a desired temperature can be produced while preventing water from freezing in the heat exchanger. can do.

According to the third aspect of the present invention, the brine valve composed of a three-way valve is provided at the confluence of the brine discharge passage and the bypass passage, or at the branch portion between the brine supply passage and the bypass passage, and the brine is provided. The cold water production system according to claim 2, wherein the opening degree of the brine supply to the heat exchanger by the valve is adjusted within a range not less than the lower limit opening degree.

According to the third aspect of the present invention, by using the three-way valve as the brine valve, the brine flow rate passed through the heat exchanger can be adjusted while maintaining the brine circulation amount to the chiller with a simple configuration and control. Can be done. Further, the opening degree of the brine valve to the heat exchanger by the brine valve can be adjusted within a range not less than the lower limit opening degree. Therefore, even if a temperature higher than the target temperature is set and controlled in order to prevent the water from freezing in the heat exchanger, the brine can continue to flow through the heat exchanger as needed, and the water reaches the target temperature. Can be cooled.

According to the fourth aspect of the present invention, the opening degree of the brine valve is adjusted within a range of an upper limit opening degree and a lower limit opening degree, and the upper limit opening degree and the lower limit opening degree can be changed. The period from closing to full opening is divided into a plurality of steps, and a lower limit opening is assigned corresponding to one or more steps for the upper limit opening, and the assigned lower limit opening has a large upper limit opening. The cold water production system according to claim 3, wherein the cold water production system is set to a large size.

According to the fourth aspect of the present invention, the opening degree of the brine valve is adjusted within the range of the upper limit opening degree and the lower limit opening degree. By setting the lower limit opening according to the upper limit opening, it is possible to keep the brine flowing through the heat exchanger as needed, and it is possible to cool the water.

Further, in the invention according to claim 5, when the outlet side water temperature becomes equal to or lower than the target temperature or the lower limit opening becomes equal to or lower than a predetermined opening for a predetermined time, the brine valve connects the heat exchanger to the heat exchanger. The cold water production system according to claim 3 or 4, wherein the supply of brine is cut off.

According to the fifth aspect of the present invention, when the water temperature on the outlet side of the heat exchanger becomes equal to or lower than the target temperature or the lower limit opening becomes equal to or lower than the predetermined opening for a predetermined time, the heat exchanger is connected by the brine valve. The supply of brine can be cut off to stop the cooling of water. As a result, it is possible to cool the water as desired while preventing the water from freezing.

According to the cold water production system of the present invention, it is possible to cool the water to the target temperature while preventing the water from freezing in the heat exchanger.

It is the schematic which shows the cold water production system of one Example of this invention. It is the schematic which shows the combination of the upper limit opening degree and the lower limit opening degree, and is shown by omitting a part. It is a flowchart which shows an example of a step-up determination process. It is a flowchart which shows an example of a step-down determination process.

Hereinafter, specific examples 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 the present embodiment cools the water by heat exchange between the brine tank 2 for storing the brine, the chiller 3 for cooling the brine from the brine tank 2, and the brine cooled by the chiller 3. A cold water tank 5 in which water is circulated between the heat exchanger 4 and the heat exchanger 4 is provided.

The brine tank 2 is a container for storing brine, and in this embodiment, the inside is open to atmospheric pressure. The brine tank 2 is provided with a liquid level detector 6, and the brine is stored up to the set liquid level. The type of brine is not particularly limited, but when cold water produced by heat exchange with brine is used for food cooling, it is a food additive so that it is safe against leakage of brine due to damage to the heat exchanger 4. It is preferable to use brine (for example, propylene glycol) which is also acceptable.

The chiller 3 includes a refrigerator (not shown). The refrigerator is a vapor compression type refrigerator in this embodiment. In this case, the refrigerator 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 reduces the pressure and temperature of the refrigerant by allowing the refrigerant from the condenser to pass through. The evaporator then evaporates the refrigerant from the expansion valve. In the evaporator, the brine from the brine tank 2 and the refrigerant of the refrigerator can be exchanged for heat without being mixed, and the brine can be cooled by the heat of vaporization of the refrigerant.

The heat exchanger 4 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 structure of the heat exchanger 4 is not particularly limited, but is, for example, a plate heat exchanger.

Brine is supplied from the brine tank 2 to the chiller 3 (more specifically, the evaporator of the refrigerator) via the brine delivery path 7. The brine cooled by the chiller 3 can be supplied to the heat exchanger 4 via the brine supply path 8. The brine after heat exchange in the heat exchanger 4 is returned to the brine tank 2 via the brine discharge path 9. A brine pump 10 is provided in the brine delivery path 7, and by operating the brine pump 10, the brine in the brine tank 2 can be circulated to and from the heat exchanger 4 via the chiller 3. Will be done.

The brine supply path 8 from the chiller 3 to the heat exchanger 4 and the brine discharge path 9 from the heat exchanger 4 to the brine tank 2 are connected by a bypass path 11. A brine valve 12 composed of a three-way valve is provided at the confluence of the brine discharge path 9 and the bypass path 11. By controlling the brine valve 12, the distribution ratio of returning the brine from the chiller 3 to the brine tank 2 via the heat exchanger 4 or returning to the brine tank 2 via the bypass path 11 is adjusted. Can be done. The brine pump 10 may be built in the chiller 3 in some cases.

The cold water tank 5 is a container for storing water, and in this embodiment, the inside is open to atmospheric pressure. The cold water tank 5 is provided with a water level detector (not shown). By controlling the supply of water to the chilled water tank 5 based on the detection signal of the water level detector, the inside of the chilled water tank 5 is maintained at the set water level.

Water is supplied from the chilled water tank 5 to the heat exchanger 4 via the chilled water inlet passage 13. The water cooled by the heat exchanger 4 is returned to the chilled water tank 5 via the chilled water outlet passage 14. A chilled water pump 15 is provided in the chilled water inlet passage 13, and by operating the chilled water pump 15, the water in the chilled water tank 5 can be circulated to and from the heat exchanger 4.

If desired, the cold water in the cold water tank 5 is supplied to a cold water demanding place (for example, a food machine) and used. The used water at the cold water demand point is either thrown away or returned to the cold water tank 5. Even in the former case (disposable cold water), water can be appropriately supplied to the cold water tank 5 as described above, so that the cold water tank 5 is maintained at the set water level. In the latter case (cold water circulation), the chilled water in the chilled water tank 5 can be circulated to and from the chilled water demanding portion, and after cooling the object to be cooled at the chilled heat demanding portion, it is returned to the chilled water tank 5.

The cold water production system 1 includes a brine temperature sensor (not shown) for detecting the temperature of brine, and a cold water temperature sensor 16 for detecting the temperature of cold water. The brine temperature sensor is built in the chiller 3 in this embodiment, and detects the brine temperature on the brine outlet side of the chiller 3. On the other hand, the chilled water temperature sensor is provided in the chilled water outlet path 14 in this embodiment, and detects the water temperature on the chilled water outlet side of the heat exchanger 4.

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 chiller 3, the brine valve 12, the brine pump 10, the chilled water pump 15, the brine temperature sensor (not shown), the chilled water temperature sensor 16, and the like, and the detection signals and elapsed time of these sensors. The chiller 3, the brine valve 12, and the pumps 10, 15 and the like are controlled based on the above.

With the start of operation of the cold water production system 1, the pumps 10, 15 and the chiller 3 are operated. By operating the brine pump 10, the brine in the brine tank 2 circulates with the chiller 3 and the heat exchanger 4. By operating the chilled water pump 15, the water in the chilled water tank 5 circulates with the heat exchanger 4. The brine is cooled in the chiller 3, and the cooled brine cools the water in the heat exchanger 4. As described above, the cold water in the cold water tank 5 or the cold heat thereof is made available at the cold water demand point. After that, the pumps 10 and 15 basically continue to operate.

During the circulation of the brine by the brine pump 10, the brine can be cooled by the chiller 3. In this embodiment, the chiller 3 is volume-controlled so that the outlet side brine temperature is set to the brine target temperature (for example, -2 ° C.). Specifically, the compressor motor is inverter-controlled so as to maintain the detection temperature of the brine temperature sensor at the brine target temperature. At this time, the following control may be performed.

That is, a plurality of temperature ranges are provided above and below the target temperature range including the brine target temperature, and the increase / decrease value of the inverter frequency is set according to each temperature range. Then, it monitors which temperature range it is in every set time and maintains the current frequency if it is in the target temperature range, while lowering the frequency if it is in the temperature range on the lower temperature side than the target temperature range, while on the high temperature side. If it is in the temperature range, it is controlled to raise the frequency.

During the operation of each of the pumps 10 and 15, the brine valve 12 is controlled so that the water temperature on the outlet side of the heat exchanger 4 becomes a set temperature. Specifically, the brine valve 12 is controlled so that the detection temperature of the chilled water temperature sensor 16 is maintained at the set temperature, and the brine from the chiller 3 is returned to the brine tank 2 via the heat exchanger 4. The distribution ratio of returning to the brine tank 2 via the bypass path 11 is adjusted. Thereby, the flow rate of the brine passing through the heat exchanger 4 can be adjusted.

Even if a temperature exceeding 0 ° C. is set as the cooling target temperature of the chilled water, the actual chilled water temperature (cold water temperature after cooling by the heat exchanger 4) fluctuates slightly up and down near the target temperature. Therefore, when the cooling target temperature of the cold water is relatively low (for example, 3 ° C. or lower), there is a possibility that the water freezes in the heat exchanger 4. In order to prevent this, in this embodiment, the opening degree of the brine valve 12 is adjusted (preferably PID control) so that the water temperature on the outlet side of the heat exchanger 4 is set to "target temperature + set value" as the set temperature. ).

The target temperature is set at a temperature exceeding 0 ° C., and is typically set at 3 ° C. or lower. In this embodiment, the target temperature is, for example, 1.0 ° C. The set value is set to a positive value of less than 1 ° C, preferably less than 0.5 ° C. In this embodiment, the set value is, for example, 0.5 ° C.

When starting the brine supply from the stopped state of the brine supply to the heat exchanger 4, the brine supply to the heat exchanger 4 is started within a range not exceeding the preset upper limit flow rate. In this embodiment, the upper limit opening degree is set for the supply opening degree of the brine to the heat exchanger 4 by the brine valve 12, and the opening degree of the brine valve 12 is adjusted within a range not exceeding the upper limit opening degree. .. Then, the upper limit opening degree can be changed according to the situation.

Further, in this embodiment, the lower limit opening degree is also set according to the upper limit opening degree, and the opening degree of the brine valve 12 is adjusted within a range not falling below the lower limit opening degree. Then, the lower limit opening degree can be changed according to the situation. The upper limit opening (upper limit flow rate) and lower limit opening (lower limit flow rate) are obtained by experiments or the like so as to exert the desired effects.

As described above, in this embodiment, the opening degree of the brine valve 12 is adjusted within the range of the upper limit opening degree and the lower limit opening degree. The upper limit opening and the lower limit opening can be changed according to the situation. Hereinafter, a more specific description will be given.

FIG. 2 is a schematic view showing a combination of an upper limit opening degree and a lower limit opening degree, and a part thereof is omitted. As shown in this figure, the upper limit opening of the brine supply to the heat exchanger 4 by the brine valve 12 is divided into a plurality of steps (stages) from fully closed (opening 0%) to fully open (opening 100%). It is divided.

More specifically, step 0 is in a fully closed state (opening 0%), step N is in a fully open state (opening 100%), and the whole is divided into "N + 1" equal parts, and step 0, step 1, and step 2 are performed. , ... It is divided up to step N. An upper limit opening degree is set for each step so that the upper limit opening degree increases as the number of steps increases. That is, when the upper limit opening of step 0 is U0 (= 0), the upper limit opening of step 1 is U1, the upper limit opening of step 2 is U2, ... The upper limit opening of step N is UN (= 100). There is a relationship of U0 <U1 <U2 <... <UN. At this time, it is preferable that the upper limit opening degree is set to increase by a predetermined opening degree each time the step is raised by one.

The lower limit opening is set as follows. First, the lower limit opening in step 0 is set to 0%, which is the same as the upper limit opening. Further, the lower limit opening LN in step N is set to be less than the upper limit opening UN (100%), preferably less than half-open (50%), and is set to, for example, 30% in this embodiment. The lower limit opening degree of each step from step 1 to step N-1 is set to be less than the upper limit opening degree of the step. At that time, the lower limit opening may be 0, but the lower limit opening is set to an opening exceeding 0 in at least one or more steps of each of the steps.

Further, a lower limit opening is assigned corresponding to one or a plurality of steps regarding the upper limit opening, and the assigned lower limit opening is set larger as the upper limit opening becomes larger. For example, the lower limit opening L0 to L4 in steps 0 to 4 is set to 0, the lower limit opening L5 in step 5 is set to a value exceeding 0, and the lower limit opening L6 in step 6 is the lower limit opening L5 in step 5. The lower limit opening degree L7 to LN after step 7 is set to a predetermined value larger than the lower limit opening degree L6 in step 6. That is, in the adjacent steps, the lower limit opening may be the same or different, but as a whole, the lower limit opening is set to be larger as the upper limit opening is larger.

As described above, when the operation of the cold water production system 1 is started, the brine pump 10 and the cold water pump 15 are operated. Then, the opening degree of the brine valve 12 is adjusted so that the detection temperature of the chilled water temperature sensor 16 is set to "target temperature + set value". When releasing from the fully closed state, first, step 1 of FIG. 2 is started. That is, first, the opening degree of the brine valve 12 is adjusted within the range of the upper limit opening degree and the lower limit opening degree in step 1. Then, the brine valve 12 is opened so as to maintain the detection temperature of the chilled water temperature sensor 16 at the "target temperature + set value" while changing the steps (in other words, the upper limit opening and the lower limit opening) according to the situation. Adjust the degree.

FIG. 3 is a flowchart showing an example of the step-up determination process, and FIG. 4 is a flowchart showing an example of the step-down determination process.

Regarding the opening degree of brine supply to the heat exchanger 4 by the brine valve 12, the opening degree of the brine valve 12 is limited from the fully closed state of step 0 (that is, the state of shutting off the brine supply to the heat exchanger 4). After opening, the step-up determination process of FIG. 3 and the step-down determination process of FIG. 4 are executed in parallel. Whether or not to increase the number of steps is performed based on the step-up determination process of FIG. 3, and whether or not to decrease the number of steps is performed based on the step-down determination process of FIG.

In the step-up determination process of FIG. 3, the water temperature on the outlet side of the heat exchanger 4 (detected temperature of the chilled water temperature sensor 16) is equal to or higher than the “target temperature + set value” (S11), and the upper limit in the current operation step. When the opening degree is continued for the step-up determination time (S12), the step is raised by one step (S13). For example, assuming that the operation is currently in step 1, the water temperature on the outlet side of the heat exchanger 4 is equal to or higher than the "target temperature + set value", and the upper limit opening U1 of step 1, which is the current operation step, is stepped up. If the determination time (for example, 5 seconds) continues, the process proceeds to step 2 and the upper limit opening degree is increased. In this way, the upper limit opening degree (and thus the flow rate at which the brine can be supplied to the heat exchanger 4) can be increased. Then, although it depends on the step, the lower limit opening can be increased as the upper limit opening is increased.

In the step-down determination process of FIG. 4, when step 1 or higher is being executed and the brine supply opening degree to the heat exchanger 4 by the brine valve 12 is fully closed (S21), the process proceeds to step 0. (S22). As described above, since the lower limit opening degree is set in the brine valve 12, the transition to step 0 may occur in the step (for example, steps 0 to 4) in which 0 is set as the lower limit opening degree. Become. Alternatively, even when the brine valve 12 is fully closed due to cold water reaching the target temperature or the like, the process proceeds to step 0.

On the other hand, even if the brine valve 12 is not fully closed, the water temperature on the outlet side of the heat exchanger 4 is "target temperature + set value + predetermined value" while the step (step X + 1 to step N) exceeding the low temperature transition step X is being executed. If the following is continued for the step-down determination time (for example, 2 seconds) (S23), the process proceeds to the low temperature transition step X (S24). The predetermined value is set to be less than the set value, preferably less than half of the set value. For example, in this embodiment, the target temperature is 1.0 ° C, and the set value is 0.5 ° C and the predetermined value is 0.1 ° C.

By the step-down determination process, after the brine valve 12 is fully closed and the process proceeds to step 0, the control can be restarted from step 1 at a predetermined timing. For example, if the detection temperature of the chilled water temperature sensor 16 is monitored and this temperature (that is, the water temperature on the outlet side of the heat exchanger 4) becomes equal to or higher than the "target temperature + set value" (or the state is continued for the step-up determination time). For example, the control from step 1 may be resumed.

By the way, during the series of control described above, if the water temperature on the outlet side of the heat exchanger 4 becomes equal to or lower than the target temperature, the brine valve 12 is fully closed to shut off the supply of brine to the heat exchanger 4. Further, even if the water temperature on the outlet side of the heat exchanger 4 does not fall below the target temperature, if the lower limit opening degree is kept below the predetermined opening degree (for example, the state of step 6 or less) for a predetermined time (for example, 15 minutes), The brine valve 12 may be fully closed to shut off the supply of brine to the heat exchanger 4. As a result, it is possible to prevent unnecessary continuation of operation (not to enter the energy saving control described later) due to balancing with the minimum load (heat dissipation and pump heat input) of the cold water side equipment.

The chiller 3 and the pumps 10 and 15 continue to operate even after the brine valve 12 is fully closed, except when the energy saving control described later is executed. Therefore, the brine can be cooled below the brine target temperature.

During the series of controls described above, the following energy-saving controls may be performed. That is, when the water temperature on the outlet side of the heat exchanger 4 continues below the target temperature for the target temperature arrival confirmation time, the brine valve 12 is closed to shut off the brine supply to the heat exchanger 4, and then the chiller 3 is stopped and the brine pump is stopped. 10 may be stopped. Further, after stopping the brine pump 10, the rotation speed of the chilled water pump 15 may be lowered to a predetermined level. After that, when the water temperature on the outlet side of the heat exchanger 4 continues to be equal to or higher than the "target temperature + chilled water pump return value" for the chilled water pump return determination time, the rotation speed of the chilled water pump 15 is returned to the steady rotation speed, and if the predetermined conditions are satisfied, After starting the brine pump 10 and the chiller 3, the opening degree adjustment of the brine valve 12 may be restarted. At that time, the process starts from step 1 in FIG. By such control, the brine pump 10 and the chiller 3 can be stopped or the rotation speed of the chilled water pump 15 can be lowered depending on the situation, and the power consumption can be reduced.

According to the cold water production system 1 of the present embodiment, in the cold water production system 1 in which the water is cooled by the heat exchanger 4 by the brine cooled by the chiller 3 to produce cold water, the brine supply path 8 and the brine for the heat exchanger 4 are produced. The discharge path 9 is connected by a bypass path 11, and a brine valve 12 composed of a three-way valve is provided at the confluence of the brine discharge path 9 and the bypass path 11. Then, by controlling the brine valve 12 based on the water temperature on the outlet side of the heat exchanger 4, the brine from the chiller 3 is returned to the brine tank 2 via the heat exchanger 4 or the brine tank via the bypass path 11. The distribution ratio of returning to 2 can be adjusted. By such distribution control, it is possible to accurately adjust the flow rate of brine passing through the heat exchanger 4 while maintaining the amount of brine circulating to the chiller 3, so that the desired temperature can be prevented while preventing the water in the heat exchanger 4 from freezing. Cold water can be produced.

Further, regarding the opening degree of brine supply to the heat exchanger 4 by the brine valve 12, the opening degree of the brine valve 12 is adjusted within a range not exceeding the upper limit opening degree to prevent water from freezing in the heat exchanger 4. can do. In particular, when starting the brine supply from the stopped state of the brine supply to the heat exchanger 4 (during that time, the brine can be cooled to the brine target temperature or lower as described above), heat exchange is performed within a range not exceeding the upper limit opening. Since the supply of brine to the vessel 4 is started, it is possible to prevent a sudden drop in the temperature of the chilled water and prevent the water in the heat exchanger 4 from freezing. Further, even if the temperature of the brine is lower than expected, it is possible to prevent the water in the heat exchanger 4 from freezing.

Further, while adjusting the opening degree of the brine valve 12 based on the outlet side water temperature of the heat exchanger 4, when the outlet side water temperature is equal to or higher than "target temperature + set value", the upper limit opening degree in the current operation step is determined by the step-up determination time. If it continues, the step (in other words, the upper limit opening) is increased. The upper limit opening is basically a situation in which it is necessary to increase the supply flow rate of brine to the heat exchanger 4 (that is, increase the cooling capacity), but it is not only the upper limit opening. By confirming the continuation of the step-up determination time, it is possible to prevent the influence of the water temperature fluctuation and the like, and to prevent the undershoot of the cold water temperature due to the excessive opening of the brine valve 12. Further, even if an undershoot occurs, the opening degree (cooling capacity) of the brine valve 12 is maintained at the upper limit value, so that the expansion of the undershoot can be suppressed. Further, it is possible to prevent an excessive increase in the upper limit opening degree by confirming that the water temperature on the outlet side of the heat exchanger 4 is higher than the target temperature, not just the upper limit opening degree.

By the way, when the cooling target temperature of the water in the heat exchanger 4 is a relatively low temperature (for example, 1 ° C.) near 0 ° C., the temperature of the cold water fluctuates slightly near the target temperature, so the brine is aimed at the target temperature. If the opening degree of the valve 12 is adjusted, the water may freeze in the heat exchanger 4. However, in this embodiment, since the water temperature on the outlet side of the heat exchanger 4 is controlled to be "target temperature + set value", freezing of water in the heat exchanger 4 can be prevented. On the other hand, if the temperature is controlled to be "target temperature + set value", the cold water cannot be set to the target temperature, but in this embodiment, the supply opening degree of brine to the heat exchanger 4 by the brine valve 12. By providing a lower limit opening in, cooling to the target temperature is possible. That is, by supplying the brine to the heat exchanger 4 within a range not exceeding the preset lower limit opening, the brine can be continuously flowed to the heat exchanger 4 as needed (in other words, depending on the step). Water can be slowly cooled to the target temperature.

The cold water production system 1 of the present invention is not limited to the configuration (including control) of the above embodiment, and can be appropriately changed. In particular, cold water including a brine tank 2 for storing brine, a chiller 3 for cooling the brine from the brine tank 2, and a heat exchanger 4 for cooling water by heat exchange between the brine cooled by the chiller 3. The manufacturing system 1 includes a brine flow rate adjusting means (for example, a brine valve 12) for adjusting the brine flow rate passing through the heat exchanger 4, and a control means for controlling the brine flow rate adjusting means based on the water temperature on the outlet side of the heat exchanger 4. , The control means controls the brine flow rate adjusting means so as to set the outlet side water temperature to "target temperature + set value" while supplying brine to the heat exchanger 4 within a range not falling below the preset lower limit flow rate. If so, the other configurations can be changed as appropriate.

For example, in the above embodiment, the brine valve 12 composed of a three-way valve is provided at the confluence of the brine discharge path 9 and the bypass path 11, but may be provided at the branch portion between the brine supply path 8 and the bypass path 11. .. Further, the brine flow rate adjusting means for adjusting the brine flow rate passing through the heat exchanger 4 is not limited to the brine valve 12 composed of a three-way valve, for example, the brine supply path 8 (and / or the brine discharge path 9) and the bypass path 11. Electric valves may be provided in each of the above and the like to adjust their opening degrees. Further, in some cases, the installation of the bypass path 11 may be omitted, the opening degree of the electric valve provided in the brine supply path 8 (or the brine discharge path 9) may be adjusted, or the brine pump 10 may be controlled by the inverter. ..

Further, in the above embodiment, the brine in the brine tank 2 was circulated so as to be returned to the brine tank 2 via the chiller 3 and the heat exchanger 4 (or the bypass path 11). May be good. That is, while the brine in the brine tank 2 is circulated with the chiller 3, the brine in the brine tank 2 may be circulated with the heat exchanger 4 in a different circulation path. Also in this case, the brine supply path 8 from the brine tank 2 to the heat exchanger 4 and the brine discharge path 9 from the heat exchanger 4 to the brine tank 2 are connected by a bypass path 11, and a brine valve composed of a three-way valve. The brine flow rate through the heat exchanger 4 may be adjusted according to 12.

Further, in the above embodiment, the water in the cold water tank 5 is circulated with the heat exchanger 4, but the water supply / drainage system for the heat exchanger 4 can be appropriately changed. For example, the installation of the cold water tank 5 may be omitted, the water from the water supply source may be passed through the heat exchanger 4 to be cooled, and then the cold water may be supplied to the cold water demand location.

Further, in the above-described embodiment, as the brine tank 2, the chiller 3, and the heat exchanger 4, the existing (existing) configuration is used, and a bypass path 11, a brine valve, and the like are added to the cold water production system of the above-described embodiment. 1 may be configured.

1 Brine production system 2 Brine tank 3 Chiller 4 Heat exchanger 5 Brine tank 6 Liquid level detector 7 Brine delivery path 8 Brine supply path 9 Brine discharge path 10 Brine pump 11 Bypass path 12 Brine valve 13 Brine inlet path 14 Cold water outlet path 15 Cold water pump 16 Cold water temperature sensor

Claims (5)

A brine tank that stores brine and
With a chiller that cools the brine from this brine tank,
In a cold water production system including a heat exchanger that cools water by exchanging heat with the brine cooled by this chiller.
A brine flow rate adjusting means for adjusting the brine flow rate through the heat exchanger, and
A control means for controlling the brine flow rate adjusting means based on the water temperature on the outlet side of the heat exchanger is provided.
The control means supplies the brine to the heat exchanger within a range not lower than the preset lower limit flow rate, and adjusts the brine flow rate so as to set the outlet side water temperature to "target temperature + set value". A cold water production system characterized by control. The brine supply path from the chiller to the heat exchanger and the brine discharge path from the heat exchanger to the brine tank are connected by a bypass path.
The brine flow rate adjusting means is a brine valve that adjusts the distribution ratio of returning the brine from the chiller to the brine tank via the heat exchanger or returning to the brine tank via the bypass path. The cold water production system according to claim 1, wherein the cold water production system is characterized. The brine valve composed of a three-way valve is provided at the confluence of the brine discharge path and the bypass path, or at the branch portion of the brine supply path and the bypass path.
The cold water production system according to claim 2, wherein the opening degree of the brine supply to the heat exchanger by the brine valve is adjusted within a range not less than the lower limit opening degree. The opening of the brine valve is adjusted within the range of the upper limit opening and the lower limit opening.
The upper limit opening and the lower limit opening can be changed.
Regarding the upper limit opening, from fully closed to fully open is divided into multiple steps.
A lower limit opening is assigned corresponding to one or more steps for the upper limit opening.
The cold water production system according to claim 3, wherein the assigned lower limit opening is set larger as the upper limit opening becomes larger. When the outlet side water temperature becomes equal to or lower than the target temperature or the lower limit opening becomes equal to or lower than a predetermined opening for a predetermined time, the brine valve shuts off the supply of brine to the heat exchanger. The cold water production system according to claim 3 or 4.

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