JP2016048126A - Supply water heating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently heat supply water to a desired temperature even when a temperature of a heat source fluid is low, in a supply water heating system using a heat pump.SOLUTION: A supply water heating system includes a plurality of heat pumps 4, 5, and a heat exchanger 25 for heating supply water. Condensers 14, 19 of the heat pumps 4, 5 are heat exchangers for a refrigerant and passing water of the heat pumps, and evaporators 17, 22 of the heat pumps 4, 5 are heat exchangers for the refrigerant and a heat source fluid of the heat pumps. The heat source fluid is passed through the evaporators 17, 22 of the heat pumps 4, 5 in series according to a determined order, or passed through a part or the whole of the evaporators in parallel, and the heat source fluid is passed to the heat exchanger 25 for heating supply water in parallel with the supply of the heat source fluid to the evaporators. The supply water to a supply water tank 3 through a water supply passage 9 is successively passed through the condensers 14, 19 of the heat pumps 4, 5 after passed through the heat exchanger 25 for heating supply water.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a feed water heating system using a heat pump.

  Conventionally, as disclosed in Patent Document 1 below, a feed water heating system using a heat pump is known. This feed water heating system (1) includes a heat pump (4) and a feed water heating heat exchanger (12), and the feed water to the feed water tank (3) via the feed water channel (8) is the feed water warming. The heat exchanger for heat (12), the supercooler (17) and the condenser (14) are passed in order. The feed water heating heat exchanger (12) is a heat exchanger for supplying water to the feed water tank (3) via the feed water channel (8) and the heat source fluid after passing through the evaporator (16). The cooler (17) is a heat exchanger for supplying water to the water supply tank (3) via the water supply channel (8) and refrigerant from the condenser (14) to the expansion valve (15). 14) is a heat exchanger for supplying water to the water supply tank (3) via the water supply channel (8) and the refrigerant from the compressor (13).

  Moreover, as disclosed in Patent Document 2 below, a heat pump device including a first refrigeration cycle (10) and a second refrigeration cycle (10 ′) in parallel is known. According to this heat pump apparatus, the intermediate hot water heated by the condenser (12 ′) of the second refrigeration cycle (10 ′) is further converted into the condenser (12) of the first refrigeration cycle (10) by the pipe (16). Pass through to heat water.

JP2013-210118A Japanese Utility Model Publication No. 60-23669 (Fig. 2)

  In the prior art, when the temperature of the heat source fluid is low (for example, 30 to 40 ° C.), it is difficult to increase the temperature of the hot water after heating with a heat pump. In particular, in the invention described in Patent Document 1, since the heat source fluid is passed through the evaporator of the heat pump and then passed to the feed water heating heat exchanger, in the feed water heating heat exchanger, There is a possibility that heating cannot be performed sufficiently. In other words, the fluid for heating the feed water in the feed water heating heat exchanger is used as a heat source for the heat pump, and after being lowered in temperature, is supplied to the feed water heating heat exchanger. In the exchanger, there is a possibility that the water supply cannot be sufficiently heated.

  Therefore, the problem to be solved by the present invention is to provide a feed water heating system that can efficiently heat feed water to a desired temperature even when the temperature of the heat source fluid is low.

  The present invention has been made to solve the above problems, and the invention according to claim 1 includes a plurality of heat pumps in which a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in an annular manner to circulate a refrigerant. A heat exchanger for supplying water that heats the water through heat exchange with the heat source fluid, and the condenser of each heat pump is a heat exchanger between the refrigerant of the heat pump and the water, The evaporator of the heat pump is a heat exchanger between the refrigerant of the heat pump and the heat source fluid, and the heat source fluid passes through the evaporator of each heat pump in series in a set order, or to some or all of the evaporators. Are passed in parallel, and in parallel with the supply of the heat source fluid to each of these evaporators, the heat source fluid is passed through the feed water heating heat exchanger, and the feed water to the feed water tank via the feed water channel is supplied to the feed water After passing through a heat exchanger for heating, A water supply warming system, characterized in that passed sequentially to the condenser of the heat pump.

  According to the first aspect of the present invention, the heat source fluid is passed through the evaporators of the heat pumps in series in a set order, or is passed in parallel through some or all of the evaporators, and in parallel therewith. Is passed through a heat exchanger for heating the feed water. On the other hand, the water supplied to the water supply tank via the water supply passage is passed through the condenser of each heat pump after being passed through the heat exchanger for water supply heating. Since the heat source fluid is passed in parallel with each evaporator in the heat exchanger for heating the feed water, the heating amount of the feed water is compared with the case where the heat source fluid after passing through each evaporator is passed in series. And the efficiency of each heat pump can be improved. Moreover, even if a heat source fluid is comparatively low temperature by the some heat pump arrange | positioned in parallel, the water flow of a water supply path can be heated as desired.

  The invention according to claim 2 includes at least a low temperature side heat pump and a high temperature side heat pump as the heat pump, and the low temperature side heat pump includes a low temperature side compressor, a low temperature side condenser, a low temperature side subcooler, and a low temperature side expansion. The high temperature side heat pump includes a high temperature side compressor, a high temperature side condenser, a high temperature side subcooler, a high temperature side expansion valve, and a high temperature side evaporator. The refrigerant is sequentially connected in an annular manner to circulate the refrigerant, and a heat source fluid is sequentially passed through the high-temperature side evaporator and the low-temperature side evaporator, and the water supply to the water supply tank via the water supply path is used for the water supply heating. The feed water heating system according to claim 1, wherein the heat exchanger, the low temperature side subcooler, the low temperature side condenser, the high temperature side subcooler, and the high temperature side condenser are sequentially passed through. is there.

  According to the second aspect of the present invention, at least a low-temperature side heat pump and a high-temperature side heat pump are provided, and the heat source fluid is passed through the high-temperature side evaporator and the low-temperature side evaporator in this order, and the water supply heating is performed in parallel therewith. Through the heat exchanger. On the other hand, the water supplied to the water supply tank via the water supply passage is sequentially passed through a heat exchanger for water supply heating, a low temperature side subcooler, a low temperature side condenser, a high temperature side subcooler, and a high temperature side condenser. Since the heat source fluid is passed in parallel with each evaporator in the heat exchanger for heating the feed water, the heating amount of the feed water is compared with the case where the heat source fluid after passing through each evaporator is passed in series. And the efficiency of each heat pump can be improved. Also, multiple heat pumps arranged in parallel use a relatively high temperature heat source fluid for heat pumps that heat relatively high temperature feed water, thus reducing the pumping temperature difference in each heat pump and improving the efficiency of the heat pump can do.

  According to a third aspect of the present invention, the low temperature side heat pump includes a low temperature side liquid gas heat exchanger, while the high temperature side heat pump includes a high temperature side liquid gas heat exchanger, and the low temperature side liquid gas heat exchanger. Is a heat exchanger between the refrigerant from the low temperature side condenser to the low temperature side subcooler and the refrigerant from the low temperature side evaporator to the low temperature side compressor, and the high temperature side liquid gas heat exchanger is The heat exchanger of the refrigerant | coolant from the said high temperature side condenser to the said high temperature side subcooler, and the refrigerant | coolant from the said high temperature side evaporator to the said high temperature side compressor is characterized by the above-mentioned. This is a water heating system.

  According to invention of Claim 3, a liquid gas heat exchanger can be installed in each heat pump, and the efficiency of each heat pump can be improved. When installing a liquid gas heat exchanger in a heat pump with a condenser and a subcooler, literally, from the evaporator to the refrigerant from the subcooler to the expansion valve and the evaporator, in order to exchange heat between the liquid refrigerant and the gas refrigerant Although it would be normal to exchange heat with the refrigerant to the compressor, in the invention according to the present claim, heat exchange is performed between the refrigerant from the condenser to the subcooler and the refrigerant from the evaporator to the compressor. Let The refrigerant at the outlet side of the relatively high temperature can ensure overheating of the gas refrigerant and improve the efficiency of the heat pump.

  The invention according to claim 4 stops the operation of the low temperature side compressor while maintaining the operation of the high temperature side compressor when a set condition is satisfied during the water supply to the water supply tank via the water supply channel. The feed water warming system according to claim 2 or claim 3, wherein

  According to the fourth aspect of the present invention, it is possible to stop the low-temperature side compressor and to warm the water supply only with the high-temperature side heat pump, if desired, during the water supply to the water supply tank via the water supply channel.

  The invention according to claim 5 is characterized in that when the heat source fluid temperature to the high temperature side evaporator exceeds a low temperature side stop temperature, the low temperature side compressor is stopped assuming that the set condition is satisfied. Item 5. A water supply heating system according to Item 4.

  According to the fifth aspect of the present invention, if the heat source fluid temperature is higher than a predetermined temperature, the low-temperature side compressor can be stopped and only the high-temperature side heat pump can warm the supplied water. Thereby, power consumption can be reduced.

  According to a sixth aspect of the present invention, during the water supply to the water supply tank via the water supply channel, the water flow rate is adjusted so as to maintain the outlet water temperature of the high temperature side condenser at a set temperature, and the water flow rate is reduced. The said low temperature side compressor is stopped as the said setting conditions are satisfy | filled when the rotation speed of the pump to adjust or the opening degree of a valve exceeds the low temperature side stop value, The said low temperature side compressor is stopped. This is a water heating system.

  According to the invention described in claim 6, by adjusting the water flow rate so as to maintain the outlet water temperature of the high-temperature side condenser at the set temperature during the water supply to the water supply tank via the water supply channel, Regardless of the water temperature or the temperature of the heat source fluid, hot water having a desired temperature can be obtained. In addition, if the number of rotations of the pump that adjusts the water flow rate or the opening of the valve becomes too large, the adjustment of the water flow rate may become impossible. Constant temperature control can be performed stably.

  According to a seventh aspect of the present invention, when the water level of the water supply tank exceeds a low temperature side stop water level, the low temperature side compressor is stopped assuming that the setting condition is satisfied. It is a feed water heating system of any one.

  According to the seventh aspect of the present invention, when the water level of the water supply tank becomes higher than a predetermined level, the low temperature side compressor is stopped and the water supply is heated only by the high temperature side heat pump. It becomes easy.

  When the water level of the water supply tank falls below a lower limit water level, the invention according to claim 8 starts water supply to the water supply tank via the water supply channel, starts each compressor, When the water level exceeds an upper limit water level, water supply to the water supply tank via the water supply channel is stopped, and the compressors are stopped. This is a water heating system.

  According to invention of Claim 8, according to the water level of a water supply tank, each heat pump can be controlled and the water supply to a water supply tank can be controlled.

  The invention according to claim 9 is characterized in that when the compressors are started from a stopped state, the high temperature side compressor is first started, and then the low temperature side compressor is started at a set timing. It is a feed water heating system of any one of claim | item 2 -8.

  If the low temperature side compressor is started first and the high temperature side compressor is started after a delay, the water flow temperature (the outlet side water temperature of the high temperature side condenser) may become too high when the high temperature side compressor is started. According to the invention of claim 9, since the high temperature side compressor is started first and the low temperature side compressor is started after a delay, the water flow temperature rises excessively when the low temperature side compressor is started. Is prevented.

  The invention according to claim 10 is characterized in that the temperature difference between the heat source fluid temperature to the feed water heating heat exchanger and the outlet water temperature of the feed water heating heat exchanger is maintained at a set value. The supply water heating system according to any one of claims 1 to 9, wherein the supply flow rate of the heat source fluid to the feed water heating heat exchanger is adjusted.

  According to the invention described in claim 10, the water supply water temperature is maintained so that the temperature difference between the heat source fluid temperature to the feed water heating heat exchanger and the outlet water temperature of the feed water heating heat exchanger is maintained at a set value. By controlling the supply flow rate of the heat source fluid to the heating heat exchanger, the heat exchange efficiency in the feed water heating heat exchanger can be increased. Also, when the heat source fluid temperature to the feed water heating heat exchanger is lower than the inlet side water temperature of the feed water heating heat exchanger, the supply of the heat source fluid to the feed water heating heat exchanger is regulated. Therefore, inconvenience of cooling the feed water when the heat source fluid is passed through the feed water heating heat exchanger is prevented.

  Furthermore, in the invention described in claim 11, heat source fluids are sequentially passed through the evaporators of the heat pumps in a set order, and the heat source fluid temperature after passing through the evaporators of the heat pumps and the heat for heating the feed water The distribution ratio of the heat source fluid to each of the evaporators and the feed water heating heat exchanger is adjusted so that the heat source fluid temperature after passing through the exchanger becomes equal. It is a feed water heating system of any one of these.

  According to the eleventh aspect of the invention, the heat source fluid temperature after passing through the evaporator of each heat pump and the heat source fluid temperature after passing through the feed water heating heat exchanger are equal to each evaporator. By adjusting the distribution ratio of the heat source fluid to the feed water heating heat exchanger, heat can be distributed in a balanced manner to each heat pump and the feed water heating heat exchanger.

  According to the feed water heating system of the present invention, even when the temperature of the heat source fluid is low, the feed water can be efficiently heated to a desired temperature.

It is the schematic which shows the feed water heating system of one Example of this invention. It is the schematic which shows the modification of the feed water heating system of FIG.

  The water supply warming system of one embodiment of the present invention is a system that heats water supplied to a water supply tank using a heat pump. As a heat pump, a plurality of vapor compression heat pumps are provided in parallel. In each heat pump, a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in an annular manner to circulate the refrigerant. The condenser of each heat pump is a heat exchanger between the refrigerant of the heat pump and the water flow, and the evaporator of each heat pump is a heat exchanger between the refrigerant of the heat pump and the heat source fluid.

  The feed water warming system further includes a feed water warming heat exchanger. This feed water heating heat exchanger warms the water flow by heat exchange with the heat source fluid. The heat source fluid is passed through the evaporators of each heat pump in series in a set order or through some or all of the evaporators in parallel. Then, in parallel with the supply of the heat source fluid to each of these heat exchangers, the heat source fluid is passed through the feed water heating heat exchanger. On the other hand, the water supply to the water supply tank via the water supply channel is passed through the condenser of each heat pump after being passed through the heat exchanger for heating the feed water. For example, the heat source fluid is passed through the evaporators of each heat pump in series in a set order, and in parallel therewith, is passed through a feed water heating heat exchanger, while the feed water to the feed water tank is used for feed water heating. After passing through the heat exchanger, the heat source fluid is sequentially passed through the condenser of each heat pump in the reverse order of passing the heat source fluid.

  Since the heat source fluid is passed in parallel with each evaporator in the heat exchanger for heating the feed water, the heating amount of the feed water is compared with the case where the heat source fluid after passing through each evaporator is passed in series. Can be increased. By preheating water supply before the heat pump, the efficiency of the heat pump can be improved. Moreover, even if a heat source fluid is comparatively low temperature, the water supply of a water supply path can be heated as desired with the several heat pump arrange | positioned in parallel. Further, by passing the heat source fluid through the feed water heating heat exchanger in parallel with each evaporator, the supply flow rate of the heat source fluid to the feed water heating heat exchanger is changed to the supply flow rate of the heat source fluid to each evaporator. Can be adjusted separately.

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

  The feed water warming system 1 of the present embodiment is a system that can heat feed water to the feed water tank 3 of the boiler 2 with the heat pumps 4, 5. The feed water tank 3 that stores the feed water to the boiler 2, and the feed water tank 3 A replenishment water tank 6 for storing water supply to the water, heat pumps 4 and 5 for heating water supplied from the replenishment water tank 6 to the water supply tank 3, and heat source water (for example, waste hot water) as a heat source for the heat pumps 4 and 5 The heat source water tank 7 is stored.

  The boiler 2 is a steam boiler, and heats the feed water from the feed water tank 3 into steam. The boiler 2 is typically adjusted in combustion quantity so as to maintain the desired steam pressure. Moreover, the pump 8 provided in the inside of the water supply path from the water supply tank 3 to the boiler 2 or the boiler 2 is controlled so that the boiler 2 may maintain the water level in a can body as desired. The steam from the boiler 2 is sent to various steam use facilities (not shown), but drain (condensed water of steam) from the steam use facility may be returned to the water supply tank 3.

  The water supply tank 3 can be supplied with water from the make-up water tank 6 through the heat supply passage 9 via the heat pumps 4, 5, and can be supplied through the supply water passage 10 without going through the heat pumps 4, 5. By controlling the operation of the water supply pump 11 provided in the water supply channel 9 and the makeup water pump 12 provided in the makeup water channel 10, via either one or both of the water supply channel 9 and the makeup water channel 10, Water can be supplied from the makeup water tank 6 to the water supply tank 3.

  In this embodiment, the feed water pump 11 can control the rotation speed by an inverter. By changing the rotation speed of the water supply pump 11, the water supply flow rate to the water supply tank 3 through the water supply path 9 can be adjusted. On the other hand, the makeup water pump 12 is on / off controlled in this embodiment.

  The makeup water tank 6 stores the water supply to the water supply tank 3. In this embodiment, soft water is used as water supply to the makeup water tank 6. That is, the soft water from which the water hardness is removed by the water softener (not shown) is supplied to the makeup water tank 6 and stored. By controlling the water supply from the water softener based on the water level of the makeup water tank 6, the water level of the makeup water tank 6 is maintained as desired.

  A plurality of heat pumps are installed in parallel, and include at least a low temperature side heat pump 4 and a high temperature side heat pump 5. Each of the heat pumps 4 and 5 is a vapor compression heat pump. The refrigerants and outputs of the heat pumps 4 and 5 may be the same or different. For example, although the heat pumps 4 and 5 are the same refrigerant, the output and mass flow rate of the compressor of the high temperature side heat pump 5 are configured to be larger than those of the low temperature side heat pump 4.

  In the low temperature side heat pump 4, the low temperature side compressor 13, the low temperature side condenser 14, the low temperature side subcooler 15, the low temperature side expansion valve 16 and the low temperature side evaporator 17 are sequentially connected in an annular manner to circulate the refrigerant. In the low-temperature side heat pump 4, the refrigerant takes heat from the outside and vaporizes in the low-temperature side evaporator 17. On the other hand, in the low-temperature side condenser 14 and the low-temperature side supercooler 15, the refrigerant dissipates heat to the outside and condenses and supercools. To do. Using this, the low temperature side heat pump 4 pumps heat from the heat source water in the low temperature side evaporator 17, and warms the water in the water supply passage 9 in the low temperature side subcooler 15 and the low temperature side condenser 14.

  Each component of the low temperature side heat pump 4 is demonstrated in order. The low temperature side compressor 13 compresses the gas refrigerant to high temperature and high pressure. The low temperature side condenser 14 is an indirect heat exchanger that exchanges heat without mixing the refrigerant of the low temperature side heat pump 4 and the water of the water supply path 9, and condenses the gas refrigerant from the low temperature side compressor 13, while the water supply path Heat 9 water. The low temperature side subcooler 15 is an indirect heat exchanger that exchanges heat without mixing the refrigerant of the low temperature side heat pump 4 and the water of the water supply channel 9, and supercools the refrigerant from the low temperature side condenser 14 while supplying water. Warm the water in path 9. The low temperature side expansion valve 16 allows the liquid refrigerant from the low temperature side subcooler 15 to pass therethrough, thereby reducing the pressure and temperature of the refrigerant. The low temperature side evaporator 17 is an indirect heat exchanger that exchanges heat without mixing the refrigerant of the low temperature side heat pump 4 and the heat source water, and evaporates the refrigerant from the low temperature side expansion valve 16 while cooling the heat source water.

  In the high temperature side heat pump 5, the high temperature side compressor 18, the high temperature side condenser 19, the high temperature side subcooler 20, the high temperature side expansion valve 21, and the high temperature side evaporator 22 are sequentially connected in an annular manner to circulate the refrigerant. In the high temperature side evaporator 22, the high temperature side heat pump 5 vaporizes the refrigerant by taking heat from the outside. In the high temperature side condenser 19 and the high temperature side subcooler 20, the refrigerant dissipates heat to the outside and condenses and supercools. To do. Using this, the high temperature side heat pump 5 pumps heat from the heat source water in the high temperature side evaporator 22, and warms the water in the water supply passage 9 in the high temperature side subcooler 20 and the high temperature side condenser 19.

  Each component of the high temperature side heat pump 5 will be described in order. The high temperature side compressor 18 compresses the gas refrigerant to a high temperature and a high pressure. The high temperature side condenser 19 is an indirect heat exchanger that exchanges heat without mixing the refrigerant of the high temperature side heat pump 5 and the water of the water supply passage 9, and condenses the gas refrigerant from the high temperature side compressor 18, while the water supply passage Heat 9 water. The high temperature side subcooler 20 is an indirect heat exchanger that exchanges heat without mixing the refrigerant of the high temperature side heat pump 5 and the water of the water supply channel 9, and supercools the refrigerant from the high temperature side condenser 19 while supplying water. Warm the water in path 9. The high temperature side expansion valve 21 decreases the pressure and temperature of the refrigerant by allowing the liquid refrigerant from the high temperature side subcooler 20 to pass therethrough. The high temperature side evaporator 22 is an indirect heat exchanger that exchanges heat without mixing the refrigerant of the high temperature side heat pump 5 and the heat source water, and evaporates the refrigerant from the high temperature side expansion valve 21 while cooling the heat source water.

  In addition, in each heat pump 4 and 5, an accumulator is installed on the inlet side of the compressors 13 and 18, an oil separator is installed on the outlet side of the compressors 13 and 18, or the outlet side of the condensers 14 and 19 A liquid receiver may be installed (between the condensers 14 and 19 and the subcoolers 15 and 20). In the present embodiment, the compressors 13 and 18 of the heat pumps 4 and 5 are on / off controlled, and the rotation speed is kept constant during operation. Based on the above, the rotational speed may be changed by an inverter.

  The heat source water tank 7 stores heat source water as a heat source for the heat pumps 4 and 5. The heat source water is, for example, waste hot water (hot water discharged from a factory or the like). In the case of the feed water warming system 1 of the present embodiment, even when the heat source water temperature is relatively low (for example, about 30 to 40 ° C.), hot water having a desired temperature can be produced as described later. The heat source water tank 7 is provided with a heat source water supply path 23 and an overflow path 24 for overflowing a predetermined amount or more of water.

  The feed water heating system 1 further includes a feed water warming heat exchanger 25. The heat exchanger 25 for heating and supplying water is an indirect heat exchanger that performs heat exchange without mixing water supplied to the water supply tank 3 via the water supply passage 9 and heat source water from the heat source water tank 7.

  Water supplied to the water supply tank 3 through the water supply path 9 is supplied to the heat exchanger 25 for supplying water heating, the low temperature side subcooler 15, the low temperature side condenser 14, the high temperature side subcooler 20, and the high temperature side condenser 19. Passed in order. On the other hand, the heat source water from the heat source water tank 7 is passed through the low temperature side evaporator 17, the high temperature side evaporator 22 and the feed water heating heat exchanger 25 in series in a set order, or a part or all of the heat. The exchanger is passed in parallel. Preferably, the heat source water from the heat source water tank 7 is passed through each of the evaporators 17 and 22 in series or in parallel in a set order, and in parallel with the supply of the heat source water to each of the evaporators 17 and 22. Then, the heat source water is passed through the heat exchanger 25 for heating the feed water.

  In the present embodiment, the heat source water from the heat source water tank 7 is branched into a first heat source supply path 27 and a second heat source supply path 28 via a heat source supply pump 26, and the heat source of the first heat source supply path 27. Water is passed through the high-temperature side evaporator 22 and the low-temperature side evaporator 17 in this order, while the heat source water in the second heat source supply path 28 is passed through the feed water heating heat exchanger 25. That is, in the present embodiment, the heat source water is sequentially passed through the high temperature side evaporator 22 and the low temperature side evaporator 17, and at the same time, the heat source water is passed through the feed water heating heat exchanger 25.

  The second heat source supply path 28 is provided with a flow rate adjustment valve 29 whose opening degree can be adjusted. By adjusting the opening degree of the flow rate adjustment valve 29, the supply flow rate (water flow rate) of the heat source water to the heat exchanger 25 for heating and heating the feed water can be adjusted.

  In the water supply path 9, a hot water temperature sensor 30 is provided on the outlet side of the high temperature side condenser 19. The hot water temperature sensor 30 detects the water temperature after passing through the high temperature side condenser 19. Based on the temperature detected by the hot water temperature sensor 30, the feed water pump 11 is controlled. Here, the feed water pump 11 is inverter-controlled so as to maintain the temperature detected by the tapping temperature sensor 30 at a set temperature (for example, 75 ° C.). That is, the flow rate of water supplied to the water supply tank 3 via the water supply path 9 is adjusted so that the temperature detected by the hot water temperature sensor 30 is maintained at the set temperature. However, in some cases, such flow rate adjustment control by the tapping temperature sensor 30 can be omitted.

  A water level detector 31 is provided in the water supply tank 3. The configuration of the water level detector 31 is not particularly limited. In the present embodiment, the water level detector 31 is an electrode type water level detector. In this case, a plurality of electrode rods 32 and 33 having different lengths are inserted and held in the water supply tank 3 with their lower end portions having different height positions. Specifically, the water supply stop electrode rod 32 and the water supply start electrode rod 33 are inserted into the water supply tank 3 with the lower end portion having a lower height in order. Furthermore, as shown by a broken line, a low temperature side stop electrode rod 34 may be provided. In that case, the height position of the lower end portion is arranged in the order of the water supply stop electrode rod 32, the low temperature side stop electrode rod 34 and the water supply start electrode rod 33. Is lowered and inserted into the water supply tank 3. In any case, each electrode rod 32 to 34 detects the presence or absence of a water level at the lower end portion depending on whether the lower end portion is immersed in water. The water level detected by the water supply stop electrode rod 32 is the water supply stop water level (upper limit water level), the water level detected by the water supply start electrode rod 33 is the water supply start water level (lower limit water level), and the water level detected by the low temperature side stop electrode rod 34 is the low temperature side stop water level. I will say.

  A heat source supply path to the heat exchanger 25 for supplying water heating (a common path upstream from the branch section of the first heat source supply path 27 and the second heat source supply path 28 is preferable. The heat source temperature sensor 35 for detecting the heat source water temperature to the feed water heating heat exchanger 25 is provided in the second heat source supply path 28 on the downstream side. On the other hand, a water temperature sensor 36 for detecting the outlet water temperature of the feed water warming heat exchanger 25 is provided on the outlet side of the feed water warming heat exchanger 25 in the feed water channel 9.

  Heat pumps 4 and 5 (particularly their compressors 13 and 18), feed water pump 11, makeup water pump 12, heat source supply pump 26, flow rate adjustment valve 29, hot water temperature sensor 30, water level detector 31, heat source temperature sensor 35 and water temperature The sensor 36 and the like are connected to a controller (not shown). And a controller controls each heat pump 4,5, each pump 11,12,26, the flow regulating valve 29, etc. based on the detection signal of each sensor 30,31,35,36, etc. Execute control.

  Water supply to the water supply tank 3 via the water supply path 9 is controlled based on the water level of the water supply tank 3. Specifically, in this embodiment, control is performed as follows. Now, when the water supply stop electrode rod 32 detects the water level and the water level of the water supply tank 3 is sufficient (that is, when it exceeds the water supply stop water level), water supply to the water supply tank 3 is unnecessary, so the water supply pump 11 Has stopped. When the water level from the water supply tank 3 to the boiler 2 is lowered and the water supply start electrode rod 33 no longer detects the water level (that is, when the water level falls below the water supply start water level), the water supply pump 11 is operated. Thus, water is supplied to the water supply tank 3 through the water supply passage 9, but when the water supply stop electrode rod 32 detects the water level, the water supply pump 11 is stopped.

  Although it is possible to supply water to the water supply tank 3 via the water supply channel 9 and also to supply water via the replenishment water channel 10, it is preferable that the water supply via the water supply channel 9 be controlled so that priority is given. For example, the water supply through the water supply channel 9 is controlled as described above so as to maintain the water level of the water supply tank 3 within the set range. However, if the water level of the water supply tank 3 cannot maintain the set range, the supply water channel 10 It is preferable to supply water to the water supply tank 3 also through the In that case, the water level detector 31 of the water supply tank 3 may be configured to be able to detect the water levels for starting and stopping the makeup water pump 12 (the makeup water start water level and the makeup water stop water level).

  While supplying water to the water supply tank 3 via the water supply path 9 (that is, during operation of the water supply pump 11), the heat source supply pump 26 is operated and the heat pumps 4 and 5 (at least the high temperature side heat pump 5 as described later) are operated. . That is, the heat source supply pump 26 and the heat pumps 4 and 5 are started and stopped so as to interlock with the water supply pump 11. However, when the heat pumps 4 and 5 are started, first, the water supply pump 11 and the heat source supply pump 26 are operated to check the supply of the water supply and heat source water to the heat pumps 4 and 5 and then the heat pumps 4 and 5 are started. preferable. The heat pumps 4 and 5 are switched between operation and stop depending on whether or not the compressors 13 and 18 are activated.

  During the water supply to the water supply tank 3 through the water supply path 9, the water supply pump 11 is preferably inverter-controlled so that the temperature detected by the tapping temperature sensor 30 is maintained at the set temperature. Hereinafter, this control is referred to as a constant tapping temperature control.

  When the heat pumps 4 and 5 are started, it is preferable to start the high temperature side heat pump 5 first and then start the low temperature side heat pump 4 at the set timing. For example, first, the high temperature side heat pump 5 is activated, and the low temperature side heat pump 4 is preferably activated after a predetermined time (for example, 5 minutes) until the operation of the high temperature side heat pump 5 is stabilized. The reason is as follows.

  That is, if the low temperature side heat pump 4 is started first and the high temperature side heat pump 5 is started after a delay, the detected temperature of the tapping temperature sensor 30 is set by the above-described constant control of the tapping temperature even when only the low temperature side heat pump 4 is operating. Since the amount of water supply is adjusted to maintain the temperature, if the high temperature side heat pump 5 on the downstream side of the water supply passage 9 is further started in that state, the temperature detected by the tapping temperature sensor 30 may exceed the set temperature. Further, since relatively high-temperature water is passed through the high-temperature side heat pump 5, when the high-temperature side heat pump 5 is started, the high-temperature side condenser 19 and the high-temperature side subcooler 20 cannot condense the refrigerant as desired. There is also a possibility that the pressure and temperature of the refrigerant 5 will be too high, and the high temperature side heat pump 5 may be interlocked. On the other hand, if the high temperature side heat pump 5 is started first, such inconvenience can be prevented.

  When the heat pumps 4 and 5 are operated to supply water from the make-up water tank 6 to the water supply tank 3 through the water supply passage 9, the water supplied from the make-up water tank 6 is supplied to the heat exchanger 25 for supplying water warming, the low-temperature side subcooling. The heat is passed through the condenser 15, the low temperature side condenser 14, the high temperature side subcooler 20, and the high temperature side condenser 19 in order. On the other hand, in the present embodiment, the heat source water from the heat source water tank 7 is sequentially passed through the high temperature side evaporator 22 and the low temperature side evaporator 17, and in parallel with this, is passed to the feed water heating heat exchanger 25. Is done. Compared with the case where heat source water is sequentially passed through each evaporator 22, 17 and feed water heating heat exchanger 25 in series, heat source water is fed to each evaporator 22, 17 and feed water heating heat exchanger 25. When passing in parallel, heat source water having a relatively high temperature can be passed through the heat exchanger 25 for heating the feed water. Thereby, the amount of heat exchange in the heat exchanger 25 for heating the feed water can be increased, and heating of the feed water in front of the heat pumps 4 and 5 is achieved, so that the power of the compressors 13 and 18 is reduced, The efficiency of the heat pumps 4 and 5 can be improved. Further, when the heat source water is passed through the evaporators 22 and 17 and the feed water heating heat exchanger 25 in order, the evaporators 22 and 17 become pressure loss elements. When the heat source water is passed through the heat exchanger 25 for use in parallel, there is an advantage that there is no such pressure loss element.

  Moreover, according to the feed water heating system 1 of the present embodiment, the heat source water through the first heat source supply path 27 is passed through the high temperature side heat pump 5 and then through the low temperature side heat pump 4 while the water supply path The water supply via 9 is passed through the low temperature side heat pump 4 and then through the high temperature side heat pump 5. In this way, heat pumps that heat relatively high-temperature feed water use heat source water that is relatively hot, so that the pumping temperature difference between the heat pumps 4 and 5 is reduced and the efficiency of the heat pumps 4 and 5 is improved. be able to.

  When both heat pumps 4 and 5 are operated and the setting condition is satisfied in the water supply to the water supply tank 3 through the water supply passage 9, the operation of the low temperature side compressor 13 is performed while maintaining the operation of the high temperature side compressor 18. You may stop. That is, water supply to the water supply tank 3 through the water supply path 9 may be achieved while operating only the high temperature side heat pump 5.

  For example, when the temperature of the heat source water to the high temperature side evaporator 22 exceeds the low temperature side stop temperature, the low temperature side compressor 13 may be stopped assuming that the setting condition is satisfied. Specifically, when the temperature detected by the heat source temperature sensor 35 exceeds the low temperature side stop temperature, the low temperature side compressor 13 may be stopped. Thereafter, on the assumption that the operation of the feed water pump 11 is continuing, if the temperature detected by the heat source temperature sensor 35 is equal to or lower than the low temperature side starting temperature, the low temperature side compressor 13 may be started. In this way, when the heat source water is at a relatively high temperature, the water supply can be heated as desired only by the high temperature side heat pump 5, and therefore the low temperature side heat pump 4 can be stopped to reduce power consumption.

  In addition, in the case where the hot water temperature constant control is performed while controlling the rotation speed of the feed water pump 11 with an inverter, the rotation speed of the feed water pump 11 exceeds a low temperature side stop value (for example, the motor of the feed water pump 11 by inverter control). If the drive frequency exceeds a preset maximum frequency), the low temperature side compressor 13 may be stopped assuming that the setting condition is satisfied. Thereafter, on the assumption that the operation of the feed water pump 11 is continuing, if the rotation speed of the feed water pump 11 becomes equal to or lower than the low temperature side start value, the low temperature side compressor 13 may be started.

  During the adjustment of the rotation speed (frequency) of the feed water pump 11 by the constant tapping temperature control, the water flow rate (the rotation speed of the feed water pump 11) becomes too high, and the temperature detected by the tapping temperature sensor 30 may not be maintained at the set temperature. In such a case, such inconvenience can be prevented by stopping the low temperature side heat pump 4. Moreover, it can prevent that the refrigerant | coolant pressure of the high temperature side heat pump 5 becomes high too much.

  Further, in the water level detector 31 of the water supply tank 3, as described above, in addition to the water supply stop electrode rod 32 and the water supply start electrode rod 33, a low temperature side stop electrode rod 34 is provided, etc. The low-temperature side compressor can be detected between the start water level (typically in the center), and if the water level in the feed water tank 3 exceeds the low-temperature side stop water level, the setting condition is satisfied. 13 may be stopped. In this case, the water supply start electrode rod 33 does not detect the water level (that is, below the water supply start water level), and both heat pumps 4 and 5 are in operation, and the low temperature side stop electrode rod 34 detects the water level when the water level rises. If it does (that is, it exceeds the low-temperature-side stop water level), the low-temperature-side heat pump 4 is first stopped, and if the water supply stop electrode rod 32 detects the water level (that is, exceeds the water-supply stop water level), the high-temperature side heat pump 5 also stops. On the contrary, when the water level is lowered, when the low temperature side stop electrode rod 34 no longer detects the water level (that is, lower than the low temperature side stop water level), the high temperature side heat pump 5 is started first, and the water supply start electrode rod 33 is further moved to the water level. Is not detected (that is, below the water supply start water level), the low temperature side heat pump 4 is also started.

  By the way, the heat exchanger 25 for water supply heating is maintained so that the temperature difference between the temperature of the heat source water to the heat exchanger 25 for water supply heating and the water temperature on the outlet side of the heat exchanger 25 for water supply warming is maintained at a set value. It is good to control the supply flow rate of the heat source water. Specifically, during the operation of the water supply pump 11, the detected temperature T1 of the water temperature sensor 36 is compared with the detected temperature T2 of the heat source temperature sensor 35 so that T2-T1 becomes a constant temperature (for example, 1 ° C.). The opening degree of the flow rate adjustment valve 29 may be adjusted. Thereby, the supply flow rate of the heat source water to the heat exchanger 25 for supplying water heating can be minimized. When the heat source water temperature to the feed water heating heat exchanger 25 is lower than the inlet water temperature of the feed water heating heat exchanger 25, the heat source water is supplied to the feed water heating heat exchanger 25. Therefore, inconvenience of cooling the feed water when the heat source water is passed through the feed water heating heat exchanger 25 is prevented.

Next, the modification of the feed water heating system 1 of a present Example is demonstrated.
FIG. 2 is a schematic diagram showing a modification of the feed water heating system 1 of FIG. This feed water heating system 1 is different from the above embodiment in that a low temperature side liquid gas heat exchanger 37 is provided in the low temperature side heat pump 4 while a high temperature side liquid gas heat exchanger 38 is provided in the high temperature side heat pump 5.

  The low temperature side liquid gas heat exchanger 37 indirectly exchanges heat without mixing the refrigerant from the low temperature side condenser 14 to the low temperature side subcooler 15 and the refrigerant from the low temperature side evaporator 17 to the low temperature side compressor 13. It is a heat exchanger. On the other hand, the high temperature side liquid gas heat exchanger 38 performs heat exchange without mixing the refrigerant from the high temperature side condenser 19 to the high temperature side subcooler 20 and the refrigerant from the high temperature side evaporator 22 to the high temperature side compressor 18. It is an indirect heat exchanger.

  Temporarily, in each heat pump 4 (5), heat exchange is performed between the refrigerant from the subcooler 15 (20) to the expansion valve 16 (21) and the refrigerant from the evaporator 17 (22) to the compressor 13 (18). When the liquid gas heat exchanger is installed, the refrigerant to the compressor 13 (18) is heated by the liquid refrigerant after being supercooled by the supercooler 15 (20), and the degree of superheat is ensured. difficult. On the other hand, as shown in FIG. 2, in each heat pump 4 (5), the refrigerant from the condenser 14 (19) to the supercooler 15 (20), and the evaporator 17 (22) to the compressor 13 (18). When the liquid gas heat exchanger 37 (38) is installed so as to exchange heat with the refrigerant to the refrigerant, a relatively high-temperature refrigerant (refrigerant from the condenser 14 (19)) before being supercooled by the supercooler 15 (20). Therefore, the gas refrigerant overheated from the evaporator 17 (22) can be secured, and the efficiency of the heat pump 4 (5) can be improved. Other configurations and controls are the same as those in the above embodiment, and thus the description thereof is omitted.

  The feed water heating system 1 of the present invention is not limited to the configuration of the above-described embodiment (including the modification), and can be changed as appropriate. In particular, a plurality of heat pumps 4 and 5 and a heat exchanger 25 for supplying water heating are provided, and the heat source water is passed through the evaporators 17 and 22 of each of the heat pumps 4 and 5 in series in a set order, or a part or All the evaporators 17 and 22 are passed in parallel, and in parallel with the supply of heat source water to each of the evaporators 17 and 22, the heat source water is passed to the feed water heating heat exchanger 25, If the water supply to the water supply tank 3 through the passage 9 is passed through the condensers 14 and 19 of the heat pumps 4 and 5 in order after the water supply warming heat exchanger 25 is passed, the other configuration (Including control) can be changed as appropriate. For example, in the embodiment, the supercoolers 15 and 20 of the heat pumps 4 and 5 may be omitted if necessary.

  In the embodiment, a third heat pump may be provided between the low temperature side heat pump 4 and the high temperature side heat pump 5. In that case, in the third heat pump, for example, heat source water from the high temperature side heat pump 5 to the low temperature side heat pump 4 is passed through the evaporator, and, for example, from the low temperature side heat pump 4 to the high temperature side. Water supply to the heat pump 5 is passed. Similarly, the number of heat pumps installed in parallel can be changed as appropriate.

  Moreover, in the said Example, although the flow volume adjustment valve 29 was provided in the 2nd heat source supply path 28 to the heat exchanger 25 for feed water heating, supply flow rate of heat source water to the heat exchanger 25 for feed water heating (or As will be described later, if the heat source water supply flow rate to the first heat source supply path 27 and the second heat source supply path 28 (ie, the distribution ratio) can be adjusted, the specific configuration can be changed as appropriate.

  For example, in the embodiment described above, the flow rate adjustment valve 29 is provided in the second heat source supply path 28 after branching from the first heat source supply path 27, and the flow rate adjustment valve 29 is detected by the heat source temperature sensor 35 and the water temperature sensor 36. However, instead of providing the flow rate adjusting valve 29 in the second heat source supply path 28, three-way as shown by the broken line in FIG. 1 is provided at the branch portion of the first heat source supply path 27 and the second heat source supply path 28. A valve 39 may be provided. The three-way valve 39 adjusts the distribution ratio of the heat source water from the heat source supply pump 26 to the first heat source supply path 27 and the second heat source supply path 28. Similar to the above embodiment, the three-way valve 39 is set so that the temperature difference between the heat source water temperature to the feed water heating heat exchanger 25 and the outlet water temperature of the feed water heating heat exchanger 25 is maintained at a set value. The supply flow rate of the heat source water to the heat exchanger 25 for heating and supplying water may be adjusted by adjusting the distribution ratio.

  Further, when such a three-way valve 39 is provided (or when the flow rate adjustment valve 29 is provided in the same manner as in the above embodiment), the heat source water temperature to the feed water warming heat exchanger 25 and the feed water warming Instead of controlling the supply flow rate of the heat source water to the feed water heating heat exchanger 25 so as to maintain the temperature difference from the outlet water temperature of the heat exchanger 25 at the set value, the following control is performed. May be. That is, the heat source water is sequentially passed through the low temperature side evaporator 17 and the high temperature side evaporator 22 in the setting order, and the heat source water heating exchange is performed in parallel with the supply of the heat source water to each of the evaporators 17 and 22. In the system in which the heat source water is passed through the condenser 25, the heat source water temperature after passing through each of the evaporators 17 and 22 and the heat source water temperature after passing through the feed water heating heat exchanger 25 are equal to each other. You may adjust the distribution ratio of the heat source water to the evaporators 17 and 22 and the heat exchanger 25 for feed water heating. For example, in FIG. 1, during operation of the heat source supply pump 26, the heat source water temperature (point A temperature) on the outlet side of the low-temperature evaporator 17 and the heat source water temperature (point A) on the outlet side of the heat exchanger 25 for heating the feed water. The temperature at point B) is monitored by a temperature sensor (not shown), and the three-way valve 39 and the like may be controlled so that both temperatures are equal. In this case, heat can be distributed to each of the evaporators 17 and 22 and the feed water heating heat exchanger 25 in a well-balanced manner.

  Moreover, in the said Example, although the water supply pump 11 was inverter-controlled in order to adjust the water supply flow volume to the water supply tank 3 via the water supply path 9, it provided in the water supply path 9 controlling the water supply pump 11 on / off. The opening degree of the valve may be adjusted. That is, if the flow rate of the water supply through the water supply channel 9 can be adjusted based on the temperature detected by the hot water temperature sensor 30, the flow rate adjustment method can be changed as appropriate.

  Moreover, in the said Example, when controlling the hot water temperature constant control, controlling the rotation speed of the feed water pump 11 with an inverter, if rotation speed (frequency) of the feed water pump 11 exceeds a low temperature side stop value, setting conditions Was satisfied, the low temperature side compressor 13 was stopped. In this regard, when the feed water flow rate of the water supply passage 9 is not adjusted by the inverter but by adjusting the opening of the valve, it may be controlled as follows. That is, when the opening degree of the valve exceeds the low temperature side stop value, the low temperature side compressor 13 may be stopped on the assumption that the set condition is satisfied. Thereafter, if the valve opening is equal to or lower than the low temperature side start value, the low temperature side compressor 13 may be started.

  Moreover, in the said Example, although the makeup water tank 6 was installed in order to store the water supply to the water supply tank 3, installation of the makeup water tank 6 may be abbreviate | omitted depending on the case, and the water supply path 9 and the replenishment directly from a water supply source. Water may be passed through the water channel 10.

  Moreover, in the said Example, although the water supply from the replenishment water tank 6 to the water supply tank 3 was enabled via the water supply path 9 and / or the replenishment water path 10, these water supply may be performed directly from a water softener. For example, in FIG. 1, the base end portions of the water supply channel 9 and the makeup water channel 10 are collectively connected to the water softener, and instead of omitting the installation of the water supply pump 11, an electric valve (motor valve) provided in the water supply channel 9 is opened. Instead of adjusting the degree and omitting the installation of the makeup water pump 12, the opening and closing of the electromagnetic valve provided in the makeup water channel 10 may be controlled.

  Moreover, although the said Example demonstrated the system which can heat the water supply to the water supply tank 3 of the boiler 2 with the heat pumps 4 and 5, the utilization place of the stored water of the water supply tank 3 is not restricted to the boiler 2, and changes suitably. Is possible. In some cases, the replenishment water tank 6 and the replenishment water channel 10 may be omitted.

  Moreover, although the said Example demonstrated the example using heat source water as a heat source of the heat pumps 4 and 5 (it is also a fluid which heats water supply in the heat exchanger 25 for water supply heating), The heat source fluid is not limited to heat source water, and various fluids such as air and exhaust gas can be used.

  Furthermore, in the said Example, although the compressors 13 and 18 of the heat pumps 4 and 5 were driven by the electric motor, the drive source of the compressors 13 and 18 is not ask | required in particular. For example, the compressors 13 and 18 may be driven by a steam motor (steam engine) that generates power using steam instead of or in addition to the electric motor, or may be driven by a gas engine. In that case, the output of the compressors 13 and 18 can be adjusted by adjusting the amount of steam supplied to the steam motor or the amount of gas supplied to the gas engine.

DESCRIPTION OF SYMBOLS 1 Water supply warming system 3 Water supply tank 4 Low temperature side heat pump 5 High temperature side heat pump 7 Heat source water tank 9 Water supply path 11 Water supply pump 13 Low temperature side compressor 14 Low temperature side condenser 15 Low temperature side subcooler 16 Low temperature side expansion valve 17 Low temperature side Evaporator 18 High-temperature side compressor 19 High-temperature side condenser 20 High-temperature side subcooler 21 High-temperature side expansion valve 22 High-temperature side evaporator 25 Heat exchanger for water supply heating 26 Heat source supply pump 27 First heat source supply path 28 Second heat source Supply path 29 Flow control valve 30 Hot water temperature sensor 31 Water level detector 32 Water supply stop electrode rod 33 Water supply start electrode rod 34 Low temperature side stop electrode rod 35 Heat source temperature sensor 36 Water temperature sensor 37 Low temperature side liquid gas heat exchanger 38 High temperature side liquid gas Heat exchanger 39 Three-way valve

Claims (11)

A compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in a ring to provide a plurality of heat pumps that circulate the refrigerant, and a heat exchanger for heating the feed water that heats water through heat exchange with the heat source fluid. ,
The condenser of each heat pump is a heat exchanger between the heat pump refrigerant and water flow,
The evaporator of each heat pump is a heat exchanger between the heat pump refrigerant and the heat source fluid,
The heat source fluid is passed in series in a set order to the evaporator of each heat pump, or in parallel to some or all of the evaporators,
In parallel with the supply of the heat source fluid to each of these evaporators, the heat source fluid is passed through the heat exchanger for heating the feed water,
The water supply heating system, wherein water supplied to the water supply tank through the water supply passage is passed through the condenser for each of the heat pumps after passing through the heat exchanger for water supply heating. As the heat pump, at least a low temperature side heat pump and a high temperature side heat pump are provided,
The low temperature side heat pump has a low temperature side compressor, a low temperature side condenser, a low temperature side subcooler, a low temperature side expansion valve and a low temperature side evaporator connected in an annular manner in order to circulate the refrigerant,
In the high temperature side heat pump, a high temperature side compressor, a high temperature side condenser, a high temperature side subcooler, a high temperature side expansion valve and a high temperature side evaporator are sequentially connected in an annular manner to circulate the refrigerant,
A heat source fluid is sequentially passed through the high temperature side evaporator and the low temperature side evaporator,
The water supply to the water supply tank via the water supply path is sequentially supplied to the water supply heating heat exchanger, the low temperature side subcooler, the low temperature side condenser, the high temperature side subcooler, and the high temperature side condenser. The feed water warming system according to claim 1, wherein the feed water warming system is passed through. While the low temperature side heat pump comprises a low temperature side liquid gas heat exchanger, the high temperature side heat pump comprises a high temperature side liquid gas heat exchanger,
The low temperature side liquid gas heat exchanger is a heat exchanger between the refrigerant from the low temperature side condenser to the low temperature side subcooler and the refrigerant from the low temperature side evaporator to the low temperature side compressor.
The high temperature side liquid gas heat exchanger is a heat exchanger between the refrigerant from the high temperature side condenser to the high temperature side subcooler and the refrigerant from the high temperature side evaporator to the high temperature side compressor. The feed water heating system according to claim 2, wherein The operation of the low temperature side compressor is stopped while maintaining the operation of the high temperature side compressor when a set condition is satisfied during water supply to the water supply tank via the water supply path. Or the feed water heating system of Claim 3. The feed water heating system according to claim 4, wherein when the heat source fluid temperature to the high temperature side evaporator exceeds a low temperature side stop temperature, the low temperature side compressor is stopped assuming that the setting condition is satisfied. . During the water supply to the water supply tank via the water supply path, the water flow rate is adjusted to maintain the outlet side water temperature of the high temperature side condenser at a set temperature,
The said low temperature side compressor is stopped as the said setting conditions are satisfy | filled when the rotation speed of the pump which adjusts the said water flow rate, or the opening degree of a valve exceeds a low temperature side stop value, The said low temperature side compressor is stopped. Item 6. A water heating system according to Item 5. When the water level of the water supply tank exceeds a low-temperature-side stop water level, the low-temperature-side compressor is stopped on the assumption that the set condition is satisfied. Temperature system. When the water level of the water supply tank is below the lower limit water level, the water supply to the water supply tank via the water supply path is started, and each compressor is started,
When the water level of the water supply tank exceeds an upper limit water level, water supply to the water supply tank via the water supply channel is stopped, and the compressors are stopped. Water supply heating system according to item. The start of the high temperature side compressor when starting each compressor from a stopped state, and then starting the low temperature side compressor at a set timing. Water supply heating system described in 1. In order to maintain the temperature difference between the heat source fluid temperature to the feed water heating heat exchanger and the outlet water temperature of the feed water warming heat exchanger at a set value, the feed water heating heat exchanger The supply water heating system according to any one of claims 1 to 9, wherein a supply flow rate of the heat source fluid is adjusted. The heat source fluid is sequentially passed through the evaporators of the heat pumps in a set order,
Each evaporator and the feed water heating heat exchanger so that the heat source fluid temperature after passing through the evaporator of each heat pump and the heat source fluid temperature after passing through the feed water heating heat exchanger are equal. The feed water heating system according to any one of claims 1 to 9, wherein a distribution ratio of the heat source fluid to the water is adjusted.

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