JP6819735B1 - Heat pump system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump system capable of continuously and efficiently heating a fluid to be heated by a heat pump. SOLUTION: Raw water is heated from a raw water tank 2 through a relay tank 34 by a condenser 13 of a heat pump 10, then returns to the raw water tank 2 and is supplied to an RO device 6. A part of the warm medium flowing out of the heat exchanger 24 of the refrigeration system 20 is circulated in the heat transfer tube 11a of the evaporator 11 of the heat pump 10. When the temperature of the raw water supplied to the condenser 13 is lower than the predetermined temperature, a part of the raw water heated by the condenser 13 is circulated from the switching valve 37 to the relay tank 34. [Selection diagram] Fig. 1

Description

The present invention relates to a heat pump system that heats a fluid using a heat pump, and relates to a heat pump system that can be applied to, for example, an application in which water supplied to a reverse osmosis membrane device is heated by a heat pump.

In the reverse osmosis membrane device (hereinafter sometimes referred to as RO device), the water supply temperature is set to about 25 ° C. in order to maintain the amount of treated water (increased flux due to decrease in water viscosity and improvement in recovery rate due to increase in silica saturation solubility). It is warming up. Steam, hot water, electric heaters, etc. are used to heat this water supply, which consumes energy.

Claim 7 of Japanese Patent Application Laid-Open No. 2012-91118 describes that the water supply of the RO apparatus is heated to 23 to 25 ° C. by a heat pump.

When the temperature of the water to be heated flowing into the condenser becomes less than the allowable value of the heat pump (for example, 16 ° C), the heat pump compresses the heat pump after a certain period of time (for example, 1 hour) regardless of the load on the heat source side. It has an automatic stop function that automatically stops to prevent excessive load on the machine and maintain the life of the heat pump. Therefore, when the water temperature of the water to be heated becomes equal to or less than the permissible value, the water to be heated cannot be continuously heated by the heat pump.

Japanese Unexamined Patent Publication No. 2012-91118

An object of the present invention is to provide a heat pump system capable of efficiently heating a fluid to be heated by a heat pump.

In the heat pump system of the present invention, a heat pump that circulates a heat medium between the evaporator and the condenser to heat the fluid to be heated in the condenser and a transport that sends the fluid to be heated from the first tank to the condenser. In a heat pump system having a line, a return line for sending a fluid to be heated from the condenser to the first tank, and a delivery line for sending the fluid heated from the first tank to a demand destination, the condensation. A temperature detecting means for detecting the temperature of the fluid to be heated flowing into the vessel, and when the temperature detected by the temperature detecting means falls below a predetermined temperature, at least a part of the fluid to be heated is transferred from the return line to the forward line. It is characterized by being provided with a circulation means for supplying to.

In one aspect of the present invention, the circulation means includes at least a relay tank provided in the forwarding line, a relay line connecting the returning line and the relay tank, and a fluid to be heated from the condenser. It has a switching means for flowing a part of the switching means to the relay line, and a control means for controlling the switching means according to the detection temperature of the temperature detecting means.

In one aspect of the present invention, when the detection temperature is lower than the predetermined temperature, the control means controls so that the flow rate of the fluid to be heated to flow through the relay line increases as the difference between the two increases. is there.

In one aspect of the present invention, the fluid to be heated is water supply to the RO device.

In one aspect of the present invention, a warm medium from a refrigeration system is supplied as a heat source fluid to the evaporator of the heat pump.

In one aspect of the present invention, the refrigerating system includes a refrigerator main body and a heat exchanger into which a refrigerant body from the refrigerating machine main body is introduced and a hot medium flows out, and flows out from the heat exchanger. A part of the warm medium is returned to the main body of the refrigerator, the rest is introduced into the evaporator of the heat pump, and the medium cooled by the evaporator is returned to the refrigerant body inflow side of the heat exchanger.

According to the heat pump system of the present invention, it is possible to prevent the temperature of the fluid to be heated flowing into the heat pump from falling below an allowable value, and it is possible to continuously and efficiently heat the fluid to be heated by the heat pump.

According to one aspect of the present invention, the water supply to the RO apparatus can be efficiently heated by a heat pump using a heat medium flowing out from the heat exchanger of the refrigeration system as a heat source.

It is a block diagram of the heat pump system which concerns on embodiment. It is a block diagram of the heat pump system which concerns on a reference example.

Hereinafter, reference examples and embodiments will be described with reference to the drawings.

FIG. 2 shows a heat pump system according to a reference example, which is a heat pump system in which the water supply of the RO device is heated by the heat pump, and the heat source of the heat pump is the exhaust heat of the refrigeration system.

The raw water to be RO-treated flows into the raw water tank (first tank) 2 from the pipe 1, is supplied from the raw water tank 2 to the condenser 13 of the heat pump 10 by the pump 31 and the pipe 32, is heated, and then is pipe 33. It is returned to the raw water tank 2 via. The heated raw water in the raw water tank 2 is supplied from the pipe 3 to the RO device 6 through the heat exchanger 4 using steam as a heat source and through the pipe 5. The permeated water of the RO device 6 is taken out from the pipe 7 as treated water, and the concentrated water flows out to the pipe 8.

The type of boiler for supplying steam to the heat exchanger 4 is not particularly limited, and may be any of a small once-through boiler, a water pipe boiler, a round boiler, an exhaust heat boiler, and the like. Although heating by steam is not required during normal operation, it is used for heating when the refrigerator main body 21 described later is stopped or when the RO device 6 is started. However, if necessary, the RO water supply may be heated by the heat exchanger 4 even during normal operation.

The heat pump 10 has a well-known configuration, and a heat medium such as CFC substitutes from the evaporator 11 is introduced into the condenser 13 at a high temperature by adiabatic compression by the compressor 12, and the heat medium from the condenser 13 is introduced into the expansion valve 14. It is configured to be introduced into the evaporator 11 via an adiabatic expansion to lower the temperature. Raw water is passed through a heat transfer tube 13a provided in the condenser 13 via a pump 31, and is heated by exchanging heat with a high-temperature heat medium.

A part of the heat medium flowing out of the heat exchanger 24 of the refrigerating system 20 is introduced into the heat transfer tube 11a provided in the evaporator 11 via the second header 25, the pipe 27, and the pump 27a. The refrigerant body whose temperature has been lowered by heat exchange with the low-temperature heat medium in the evaporator 11 is returned to the first header 23 via the pipe 28 and is introduced again into the heat exchanger 24.

The refrigerating system 20 sends the refrigerant body cooled by the refrigerator main body 21 such as the turbo refrigerator and the absorption chiller from the medium delivery unit 21a of the refrigerator main body 21 to the pipe 22 and the first header 23, and the first It is supplied from 1 header 23 to a heat exchanger 24 such as an air conditioner via a pump 23a, absorbs ambient heat, and cools the ambient. A part of the warm medium that has been heated by absorbing the ambient heat by the heat exchanger 24 returns from the second header 25 to the medium return portion 21b of the refrigerator main body 21 via the pipe 26 and the medium circulation pump 26a. ..

The rest of the heat medium flowing out of the heat exchanger 24 is circulated to the heat transfer tube 11a of the evaporator 11 via the pipe 27 and the valve 27a branched from the pipe 26, exchanges heat with the heat pump heat medium, lowers the temperature, and cools. It serves as a medium, returns from the pipe 28 to the first header 23, merges with the refrigerant body from the refrigerator main body 21, and flows into the heat exchanger 24.

In this reference example, as described above, a warm medium flowing out of the heat exchanger 24 is used as the heat source fluid circulated in the heat transfer tube 11a of the evaporator 11 of the heat pump 10. Further, the cooled refrigerant body is returned to the heat exchanger 24 by passing through the heat transfer tube 11a of the evaporator 11 of the heat pump 10.

The refrigerator main body 21 of the refrigerating system 20 uses cold water from the cooling tower 40 as a low-temperature fluid for cooling.

In the cooling tower 40, the cooling water sprinkled from the sprinkler pipe 41 comes into contact with the air introduced from the louver 43 while flowing down the filler layer 42, and is cooled by the latent heat of evaporation to become cold water, and becomes pit 44 (cooling tower). It is stored in the lower water tank). The air containing steam is exhausted into the atmosphere by the fan 48. The cold water in the pit 44 is supplied to the refrigerator main body 21 via the pump 45 and the pipe 46, and heats are exchanged to raise the temperature. The warming water from the refrigerator main body 21 is returned to the sprinkler pipe 41 via the pipe 47.

In the heat pump system of FIG. 2 configured in this way, the raw water in the raw water tank 2 is heated by the heat pump 10 and then from the raw water tank 2 by the heat exchanger 4 as needed, and then transferred to the RO device 6. Be supplied.

In this reference example, when the temperature of the raw water flowing into the condenser 13 through the pipe 32 becomes equal to or lower than the permissible value (for example, 16 ° C.) of the heat pump 10, the refrigerating system 20 is loaded for a certain period of time (for example). After 1 hour), it has an automatic stop function of automatically stopping the heat pump 10 in order to prevent an excessive load on the compressor 12 and maintain the life of the heat pump 10. Therefore, when the temperature of the raw water flowing into the condenser 13 is less than the permissible value, the RO water supply cannot be heated by the heat pump 10.

Therefore, in the present invention, as in the embodiment of FIG. 1 described below, by providing a means for raising the temperature of the raw water flowing into the condenser 13, the automatic stop function is not activated and the RO water supply is supplied. It is designed to be constantly heated by a heat pump.

In the heat pump system of FIG. 1, the raw water in the raw water tank 2 is sent to the relay tank (second tank) 34 via the pump 33a and the valve 33b. The relay tank 34 is provided with a water level sensor (not shown), and the pump 33a and the valve 33b are operated in conjunction with the water level sensor so that the water level in the relay tank 34 is maintained at a predetermined water level.

The water in the relay tank 34 is sent to the condenser 13 via the pump 31 and the pipe 32, heated by flowing through the heat transfer tube 13a, and flows out to the pipe 33.

In this embodiment, the end of the pipe 33 is connected to the inflow port of the switching valve 37 as the flow path switching means. The first outflow port of the switching valve 37 is connected to the relay tank 34 via the pipe 38, and the second outflow port is connected to the raw water tank 2 via the pipe 39. Although the switching valve 37 is a three-way valve type, a two-way type valve may be provided in the pipes 38 and 39.

A temperature sensor 35 for measuring the inflow water temperature to the condenser 13 is installed in the pipe 32, and this detection signal is input to the valve controller 36. Valve controller 36, when the detected temperature T of the temperature sensor 35 is lower than the predetermined temperature T ₀ causes communication between the pipe 33 pipe 38, the relay tank through the pipe 38 at least part of the effluent of the condenser 13 Water is sent to 34. When the detected water temperature T is higher than the predetermined temperature T ₀ , the pipes 33 and 39 are communicated with each other, and most or all of the outflow water of the condenser 13 is returned to the raw water tank 2.

When the detected water temperature T is lower than the predetermined temperature T _0, it is preferable to increase the ratio of water supplied from the pipe 33 to the relay tank 34 as T ₀ −T becomes larger.

When the detected water temperature T is higher than the predetermined temperature T ₀ , the proportion of water supplied from the pipe 33 to the relay tank 34 is reduced as T ₀ −T becomes larger, and the preset temperature _TH ( _TH > T ₀ ) is reached. If so, it is preferable to send the entire amount of water from the pipe 33 to the raw water tank 2.

The predetermined temperature is preferably a reference temperature for automatic stop of the heat pump 10 (16 ° C. in this case) or a temperature slightly higher than that (for example, within 21 to 25 ° C.).

It is preferable that the capacity of the relay tank 34 is smaller than that of the raw water tank 2 and further satisfies the following conditions that the automatic stop due to the temperature of the heat pump does not operate.
V <(t _L × Q) / (C _p × ( _TL −T _min ))
V: Relay tank capacity (m ³ )
C _p : Specific heat of water (Mcal / m ³ )
_TL : Automatic stop reference temperature (° C)
t _L : Time from automatic stop reference temperature detection to automatic designation operation (hr)
T _min : Minimum temperature condition (° C) for make-up water for the heat pump
Q: Heat pump heating capacity (Mcal / h)

For example, the heating capacity (Q) of the heat pump is 400 Mcal / h, and the maximum capacity of the relay tank 34 that can heat from 5 ° C to 16 ° C within 0.5 hours is the specific heat C _p = 1 Mcal / m ^{3 of} water. Then, V = (0.5 × 400) / [1 × (16-5)] = 18m ³ .

Under the above conditions, if the raw water tank is less than 18 m ³ , the relay tank may be omitted.

According to this embodiment, the heat pump 10 is automatically stopped because the temperature of the water supplied to the heat transfer tube 13a of the condenser 13 of the heat pump 10 is controlled to be equal to or higher than the reference temperature T _0. The water supply to the RO device 6 can be continuously and stably heated without any problem.

Also in this embodiment, as in the reference example of FIG. 2, as the heat source of the heat pump 10, a warm medium flowing out from the heat exchanger 24 such as the air conditioner installed in the refrigeration system 20 is used, and the refrigerator The freezing load of the main body 21 can be reduced.

Although the steam heat exchanger 4 is used in FIG. 1, a heat exchanger using a heat source other than steam may be installed instead of the steam heat exchanger 4. The present invention can also be applied to applications for heating fluids other than RO device water supply. Further, the heat source of the heat pump 10 may be a heat source other than the exhaust heat of the refrigeration system.

2 Raw water tank 4 Steam heat exchanger 6 RO device 10 Heat pump 11 Evaporator 12 Compressor 13 Condenser 14 Expansion valve 20 Refrigeration system 21 Refrigerator body 24 Heat exchanger 34 Relay tank 35 Temperature sensor 37 Switching valve 40 Cooling tower

Claims (5)

A heat pump that circulates a heat medium between the evaporator and the condenser and heats the fluid to be heated in the condenser.
A forward line that sends the fluid to be heated from the first tank to the condenser, and a return line that sends the fluid to be heated from the condenser to the first tank.
In a heat pump system having a delivery line for sending a fluid heated from the first tank to a demand destination.
A temperature detecting means for detecting the temperature of the fluid to be heated flowing into the condenser, and
A circulation means for supplying at least a part of the fluid to be heated from the return line to the forward line when the temperature detected by the temperature detection means falls below a predetermined temperature is provided .
The circulation means
The relay tank provided on the outbound line and
A relay line connecting the return line and the relay tank,
A switching means for flowing at least a part of the fluid to be heated from the condenser to the relay line, and
With a control means that controls the switching means according to the detection temperature of the temperature detecting means
A heat pump system characterized by having . Wherein, when said detected temperature is below the predetermined temperature, the more difference between the two is large, the heat pump system of claim 1 performs control so as to increase the flow rate of the heated fluid to flow to the relay line .. The heat pump system according to claim 1 or 2 , wherein the fluid to be heated is water supply to the RO device. The heat pump system according to any one of claims 1 to 3 , wherein a warm medium from a refrigeration system is supplied as a heat source fluid to the evaporator of the heat pump. The refrigeration system includes a refrigerator main body and a heat exchanger into which a refrigerant body from the refrigerator main body is introduced and a hot medium flows out.
A part of the warm medium flowing out of the heat exchanger is returned to the refrigerator body, the rest is introduced into the evaporator of the heat pump, and the medium cooled by the evaporator is returned to the refrigerant body inflow side of the heat exchanger. The heat pump system according to claim 4 , characterized in that.

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