JP7303546B2 - circulation hot water system - Google Patents

Description

The present invention relates to a circulating hot water system in which hot water from a heat exchanger is returned to a tank through a user.

2. Description of the Related Art Conventionally, there is known a water heater, which is a type of heating system that generates hot water or hot water by heating cold water or hot water with a heating fluid such as steam (for example, Patent Document 1). The generated hot or hot water is supplied to the user. As one type of such hot water supply apparatus, there is a circulating hot water supply system. In a circulating hot water system, by providing a return pipe to the tank in the pipe from the heat exchanger, hot or hot water is circulated to keep the water temperature constant even when it is not being used. there is Therefore, even at a place away from the water heater, the user can use warm water or hot water with almost no waiting time.

Japanese Patent No. 5103495

In such a circulating hot water supply system, it may be desired to supply hot water or hot water at a plurality of temperatures. In a circulating hot water system, as the circulation progresses, the temperature of the water in the tank in the hot water system also rises to the temperature of the hot or hot water supplied to the user. Therefore, when the temperature of hot or hot water supplied to the user is to be lowered, the water temperature in the tank must also be lowered by heat radiation, but a long waiting time is required to lower the water temperature in the tank by natural heat radiation. need. In order to eliminate the waiting time, some tanks are provided as many as the set temperature of the water in the tank, but the system becomes complicated and the cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circulating hot water supply system that can quickly reach the set temperature even when the set temperature is lowered.

In order to achieve the above object, the circulation type hot water supply system of the present invention is a heat exchange system in which hot water is generated by heat exchange between a tank in which hot water is stored and a heating fluid and hot water drawn out from the tank. A circulating hot water supply system in which hot water from the heat exchanger is returned to the tank through a user, and is provided in a hot water supply passage for supplying hot water from the tank to the heat exchanger a pump and a temperature sensor; a cold water control valve for opening and closing a cold water mixing passage for mixing cold water into the tank; a heating fluid control valve for adjusting the amount of heating fluid supplied to the heat exchanger; temperature setting means for opening and closing the hot fluid control valve or the cold water control valve such that the hot water temperature sensed by the temperature sensor is at a selected temperature set point. Said heating fluid is for example steam.

According to this configuration, the temperature setting means opens and closes the heating fluid control valve or the cold water control valve so that the hot water temperature detected by the temperature sensor becomes the selected temperature setting value. As a result, even when the set temperature is lowered, the set temperature can be reached quickly. Therefore, it is not necessary to provide as many tanks as the number of preset water temperatures in the tanks.

In the present invention, the cold water mixing passage may branch off from a cooling water supply passage for supplying cold water to the tank when the water level in the tank drops below a set level. According to this configuration, since it is not necessary to provide a separate water supply port exclusively for the cold water mixing passage, it is possible to suppress an increase in the number of water supply ports.

According to the circulating hot water supply system of the present invention, even when the set temperature is lowered, the set temperature can be reached quickly.

1 is a schematic configuration diagram showing a circulating hot water supply system according to a first embodiment of the present invention; FIG.

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a circulating hot water supply system 1 according to a first embodiment of the present invention. A circulating hot water supply system 1 includes a tank 2 that stores hot water W1, and a heat exchanger 4 that generates hot water W2 by heat exchange between a heating fluid F1 and the hot water W1 drawn out from the tank 2. , hot water W2 from the heat exchanger 4 is returned to the tank 2 via the user.

In this embodiment, the hot water W2 supplied to the user is set at 98°C. Such hot water W2 is used for operations such as sterilization and sterilization in food manufacturers, for example. Moreover, in this embodiment, steam is used as the heating fluid F1. However, the heating fluid F1 is not limited to steam, and may be high-temperature, high-pressure water, for example.

A hot water supply passage 6 for supplying hot water W2 to the heat exchanger 4 is connected to the tank 2 . A pump 8 and a first temperature sensor 10 are provided in the hot water supply passage 6 . The pump 8 pumps the hot water W1 in the tank 2 . The first temperature sensor 10 detects the temperature of the hot water W<b>1 in the hot water supply passage 6 (hot water temperature), that is, the temperature of the hot water in the tank 2 . In this embodiment, the first temperature sensor 10 is arranged downstream of the pump 8 and upstream of the heat exchanger 4 . The hot water supply passage 6 is also provided with a strainer 12 for removing foreign matter in the hot water W1 supplied to the pump 8 and a flow meter 14 for detecting the flow rate of the hot water W1.

A downstream end of the hot water supply passage 6 is connected to the hot water inlet 4 a of the heat exchanger 4 . On the other hand, the hot water outlet 4 b of the heat exchanger 4 is connected to the upstream end of the hot water supply passage 16 . The hot water W1 flowing into the heat exchanger 4 from the hot water inlet 4a undergoes heat exchange with the heating fluid F1 in the heat exchanger 4 to become hot water W2. The generated hot water W2 is led out to the hot water supply passage 16 from the hot water outlet 4b. The configuration of the heat exchanger 4 on the heating fluid F1 side will be described later.

The hot water supply passage 16 is provided with a second temperature sensor 18, a pressure sensor 19, and a check valve 17 on the upstream side thereof. A second temperature sensor 18 detects the temperature of the hot water W2 in the hot water supply passage 16 . The inlet of the user side pipe 100 is connected to the downstream end of the hot water supply passage 16 . A safety device 20 is provided upstream of the user-side pipe 100 in the hot water supply passage 16 . When the safety device 20 detects abnormal pressure in the hot water supply passage 16, the safety device 20 automatically opens the valve, and the hot water W2 is returned to the tank 2 through the bypass passage 21.

A hot water return passage 22 is connected to the outlet of the user side pipe 100 . The hot water W2 supplied to the user side pipe 100 is returned to the tank 2 through the hot water return passage 22. As shown in FIG. A solenoid valve 24 is provided in the hot water return passage 22 . The electromagnetic valve 24 is closed, for example, when stopping the supply of the hot water W2 to the user-side pipe 100 .

A cooling water supply passage 26 is connected to the tank 2 . A ball tap 28 is provided at the downstream end of the cooling water supply passage 26 . In other words, the cooling water supply passage 26 supplies the cold water W3 to the tank 2 when the water level in the tank 2 falls below the set level to keep the water level at the set level. The cold water W3 is tap water, for example, and is supplied to the cooling water supply passage 26 from the water supply port 26a that is the inlet of the cooling water supply passage 26. As shown in FIG.

A cold water mixing passage 30 branches off from the cooling water supply passage 26 . A cold water control valve 32 is provided in the cold water mixing passage 30 . Cold water W3 is mixed into the tank 2 by opening the cold water control valve 32 . The cold water control valve 32 of this embodiment is an electromagnetic valve. However, the cold water control valve 32 is not limited to an electromagnetic valve, and may be an electric ball valve or a hydraulic valve, for example.

The configuration of the heating fluid (steam) F1 side in the heat exchanger 4 will be described. The hot water supply system 1 has a heating fluid supply passage 34 that supplies a heating fluid F<b>1 to the heat exchanger 4 . A heating fluid control valve 36 and a third temperature sensor 38 are provided in the heating fluid supply passage 34 . A heating fluid control valve 36 regulates the amount of heating fluid f1 supplied to the heat exchanger 4 . The heating fluid control valve 36 of this embodiment is an electric ball valve. However, the heating fluid control valve 36 is not limited to this. A third temperature sensor 38 detects the temperature of the heating fluid F<b>1 in the heating fluid supply passage 34 . The heating fluid supply passage 34 is also provided with a strainer 40 for removing foreign matter from the heating fluid F1 introduced into the heating fluid control valve 36 .

A downstream end of the heating fluid supply passage 34 is connected to the heating fluid inlet 4 c of the heat exchanger 4 . On the other hand, the upstream end of the heating fluid discharge passage 42 is connected to the heating fluid outlet 4 d of the heat exchanger 4 . The heating fluid F1 flowing into the heat exchanger 4 from the heating fluid inlet 4c exchanges heat with the hot water W1 in the heat exchanger 4, heats the hot water W1, and then flows through the heating fluid outlet 4d to the heating fluid discharge passage 42. is derived to

A fourth temperature sensor 44 is provided in the heating fluid discharge passage 42 . A fourth temperature sensor 44 detects the temperature of the heating fluid F<b>1 in the heating fluid discharge passage 42 . The first to fourth temperature sensors 10, 18, 38, 44 determine the operating state, deterioration state, etc. of the heat exchanger. A steam trap 46 is provided at the downstream end of the heating fluid discharge passage 42 . Condensate (drain) F2 in the heating fluid discharge passage 42 is discharged from the drain passage 48 by the steam trap 46 .

A drain extraction passage 50 is connected to the upstream side of the heating fluid control valve 36 in the heating fluid supply passage 34 . A steam trap 52 is also provided at the downstream end of the drain extraction passage 50 .

Each device of hot water supply system 1 is controlled by control device 54 . Specifically, the output values of the first to fourth temperature sensors 10, 18, 38, 44, the pressure sensor 20a, etc. are input to the control device 54, and the pump 8, the solenoid valve 24, the cold water control valve 32, the heating fluid control Devices such as the valve 36 operate according to commands from the control device 54 . The control device 54 may be an electric circuit including a relay or the like, or may be an arithmetic device in which a program is implemented.

The control device 54 comprises temperature control means 56 . When the temperature of the hot water W1 detected by the first temperature sensor 10 exceeds a predetermined value T1, the temperature adjusting means 56 opens the cold water control valve 32 to lower the temperature of the hot water W1. In this embodiment, the predetermined value T1 is 85°C. However, the predetermined value T1 is not limited to 85.degree.

The control device 54 further comprises temperature setting means 58 . The circulating hot water supply system 1 of the present embodiment is configured to be able to respond even when the temperature target value of the hot water W2 supplied to the user is changed. That is, in this embodiment, the hot water W2 of 98° C. is supplied to the user. It is configured such that the temperature setting value T2 can be changed. The temperature setting means 58 is configured so that a plurality of temperature setting values T2 (eg, 85° C., 60° C., 40° C.) can be selected. For example, the temperature setting value T2 of 85°C for the hot water W1 corresponds to the temperature target value of 95°C for the hot water W2, the temperature setting value T2 of 60°C to the hot water W2 temperature target value of 70°C, and the hot water W1 The temperature set value T2 of 40° C. corresponds to the temperature target value of 50° C. of the hot water W2.

The temperature setting means 58 further controls the heating fluid control valve 38 or the cold water control valve 32 so that the temperature of the hot water W2 detected by the first temperature sensor 10 becomes the selected temperature setting value T2. Specifically, when raising the temperature setting value T2, the degree of opening of the heating fluid control valve 38 is increased to increase the supply amount of the heating fluid F1. When lowering the temperature setting value T2, the cold water control valve 32 is opened to mix cold water W3 into the tank 2. - 特許庁As a result, the temperature of the hot water W1 in the tank 2 can be lowered more quickly than when the heat is naturally released.

The change of the temperature setting value T2 by the temperature setting means 58 can be set from the remote external terminal 60. FIG. The external terminal 60 may be a hard switch, a soft switch displayed on a touch panel or the like, or input means such as a keyboard or mouse of a central processing unit. The control device 54 and the external terminal 60 are connected by a wiring 62 such as an electric wire, LAN cable, or optical fiber. Further, the temperature target value of the hot water W2 or the temperature set value T2 of the hot water W1 may be automatically changed by a program during the working hours.

Next, the operation of the circulation hot water supply system 1 of this embodiment will be described. When the system operates, the pump 8 supplies hot water W1 in the tank 2 to the heat exchanger 4 . The hot water W1 is heat-exchanged with the heating fluid F1 in the heat exchanger 4 to generate hot water W2. The hot water W2 is supplied to the user-side pipe 100 and returned to the tank 2 through the hot water return passage 22 .

When the hot water W2 is returned to the tank 2, the temperature of the hot water W1 in the tank 2 rises. For example, as the circulation progresses, it may reach 98° C., which is the same as the hot water W2. When the hot water temperature T detected by the first temperature sensor 10 exceeds a predetermined value T1 (for example, 85° C.), the temperature control means 56 opens the cold water control valve 32 to mix cold water W3 into the tank 2 . As a result, the temperature of the hot water W1 in the tank 2 is lowered to avoid reaching 98°C. When the water level of the hot water W1 in the tank 2 exceeds the upper limit due to the mixing of the cold water W3, the hot water W1 is discharged to the outside through the overflow passage 64 . The timing of closing the cold water control valve 32 may be set by a time limit device such as a timer, and the valve may be closed when the hot water temperature T falls below a set value (eg, 80° C.).

For example, when the temperature target value of the hot water W2 in the circulation hot water supply system 1 of the present embodiment is lowered from 98°C to 70°C, the temperature setting means 58 selects the temperature setting value T2=60°C of the hot water W1. The temperature setting means 58 compares the hot water temperature T (eg, 85° C.) detected by the first temperature sensor 10 with the selected temperature setting value T2 (60° C.). In this case, since the detected hot water temperature T is higher than the temperature set value T2 (T>T2), the cold water control valve 32 is opened so that both become the same (T=T2).

As a result, the cold water W3 is mixed in the tank 2, and the temperature of the hot water W1 is quickly lowered. When the water level of the hot water W1 in the tank 2 exceeds the upper limit due to the mixing of the cold water W3, the hot water W1 is discharged to the outside through the overflow passage 64 . When both become the same (T=T2), the cold water control valve 32 is closed. When increasing the temperature setting value T2 of the hot water W1, the opening of the heating fluid control valve 36 of the heat exchanger 4 is increased to raise the temperature of the hot water W2 from the heat exchanger 4. The temperature of the hot water W1 is quickly raised to the temperature set value T2. In this way, the temperature of the hot water W1 in the tank 2 can be rapidly raised and lowered, so that the temperature setting value T2 of the hot water W1 can be easily changed automatically by a program during working hours.

According to the above configuration, when the hot water temperature T detected by the first temperature sensor 10 exceeds the predetermined value T1 (T>T1), the cold water control valve 32 is opened by the temperature control means 56 and cold water is supplied to the tank 2. W3 is mixed. As a result, even if the hot water W2 in the user-side pipe 100 is 98° C., the temperature of the hot water W1 in the tank 2 is suppressed below the predetermined value T1 (85° C.). As a result, the occurrence of cavitation in the pump 8 can be prevented.

When lowering the temperature setting value T2 of the hot water W1 in the tank 2, the temperature setting means 58 operates the cold water control valve 32 so that the hot water temperature T detected by the first temperature sensor 10 becomes the selected temperature setting value T2. open the valve. As a result, the temperature of the hot water W1 in the tank 2 is lowered. As a result, even when the temperature setting value T2 is lowered, the temperature of the hot water W1 can reach the temperature setting value T2 more quickly than in the case of natural heat radiation. Therefore, it is not necessary to provide the number of temperature setting values T2, that is, three tanks.

The cold water mixing passage 30 branches off from the cooling water supply passage 26 . Therefore, since it is not necessary to provide a separate water supply port exclusively for the cold water mixing passage, it is possible to suppress an increase in the number of water supply ports 26a.

In the above embodiment, since steam is used as the heating fluid F1, the heat exchanger 4 can quickly raise the temperature of the hot water W2.

The present invention is not limited to the above embodiments, and various additions, changes, or deletions are possible without departing from the scope of the present invention. In the above embodiment, the first temperature sensor 10 is arranged downstream of the pump 8 and upstream of the heat exchanger 4, but the first temperature sensor 10 may be provided in the hot water supply passage 6. The arrangement is not limited to the above embodiment. Further, in the above embodiment, the cold water mixing passage 30 is branched from the cooling water replenishing passage 26, but it may be provided separately from the cooling water replenishing passage 26 and independently. Accordingly, such are also included within the scope of this invention.

1 circulating hot water supply system 2 tank 4 heat exchanger 6 hot water supply passage 8 pump 10 first temperature sensor (temperature sensor)
26 cooling water supply passage 30 cold water mixing passage 32 cold water control valve 38 heating fluid control valve 58 temperature setting means F1 heating fluid W1 hot water W2 hot water W3 cold water

Claims (2)

A tank for storing hot water and a heat exchanger for generating hot water by heat exchange between the heating fluid and the hot water drawn from the tank, the hot water from the heat exchanger passing through the user A circulating hot water system that returns to a tank,
a pump and a temperature sensor provided in a hot water supply passage that supplies hot water from the tank to the heat exchanger;
a cold water control valve that opens and closes a cold water mixing passage for mixing cold water into the tank;
a heating fluid control valve for adjusting the amount of heating fluid supplied to the heat exchanger;
a plurality of temperature setting values can be selected, and temperature setting means for opening and closing the heating fluid control valve or the cold water control valve so that the hot water temperature detected by the temperature sensor reaches the selected temperature setting value; prepared,
The cold water mixing passage is a circulating hot water supply system in which the cold water supply passage branches off from a cooling water supply passage for supplying cold water to the tank when the water level in the tank drops below a set level. 2. The circulation hot water system according to claim 1 , wherein said heating fluid is steam.

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