JP6694582B2 - Water supply heating system - Google Patents

Description

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

  BACKGROUND ART Conventionally, as disclosed in Patent Document 1 below, there is known a system capable of heating water supply to a water supply tank (3) of a boiler (2) using a heat pump (4). In the heat pump (4), a compressor (12), a condenser (13), an expansion valve (14) and an evaporator (15) are sequentially connected in an annular shape to circulate a refrigerant, and the refrigerant is passed through the evaporator (15). Heat is drawn from the heat source fluid to warm the water passed through the condenser (13). Water can be supplied to the water supply tank (3) by the water supply passage (8) via the condenser (13) and can be supplied by the makeup water passage (9) without passing through the condenser (13). Water supply to the water supply tank (3) via the water supply channel (8) starts when the water level in the water supply tank (3) becomes lower than the water supply start water level (H1), and the water supply stop water level (higher than this water supply start water level It stops when it exceeds H2). Water supply to the water supply tank (3) via the makeup water channel (9) starts when the water level in the water supply tank (3) falls below the makeup water start water level (H3) lower than the water supply start water level, and from the water supply start water level. Is higher, but lower than the water supply stop water level, which is lower than the make-up water stop water level (H4), it stops.

  Therefore, the water supply tank (3) is preferentially supplied with water through the water supply passage (8), and when it is insufficient, water is also supplied through the makeup water supply passage (9). By supplying heat to the water supply tank (3) through the water supply passage (8) and operating the heat pump (4), the water supply to the water supply tank (3) can be heated. At this time, the feed water flow rate is adjusted so as to maintain the outlet side water temperature (29) of the condenser (13) at the target temperature (outlet temperature constant control). On the other hand, the water supply via the makeup water channel (9) is on / off controlled without adjusting the flow rate, and does not pass through the heat pump (4), so the water tank remains at a lower temperature (normal temperature) than the water supply via the water channel (8). It is supplied to (3).

JP-A-2015-78827 (Claims 1, 3, and FIG. 1)

  In the prior art, the target temperature of the constant heated water temperature control is set regardless of the water temperature and water level in the water supply tank. Further, in the prior art, if the water temperature in the water supply tank is to be raised, the target temperature for the hot water outlet temperature constant control will be set high. However, in the hot water discharge temperature constant control, the higher the target temperature is set, the lower the water supply flow rate is, so that the water level in the water supply tank is lowered and relatively low-temperature water is easily supplied to the water supply tank via the makeup water passage. On the other hand, if the water temperature in the water supply tank is too high, cavitation may occur in the water supply pump from the water supply tank to the boiler or the like.

  Therefore, the problem to be solved by the present invention is to provide a water supply heating system capable of performing a desired hot water outlet temperature constant control in accordance with the situation in the water supply tank (specifically, the water temperature and / or the water level). To do. Another object of the present invention is to provide a water supply heating system that can prevent a decrease in water temperature in a water supply tank and a shortage of stored water without causing cavitation in a water supply pump from a water supply tank to a boiler or the like.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is such that a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in an annular shape to circulate a refrigerant to cause the evaporation. A heat pump that draws heat from a heat source fluid that is passed through a condenser and heats the water that is passed through the condenser, and water can be supplied through a water supply passage through the condenser, and is replenished without passing through the condenser. A water supply tank capable of supplying water by a water passage, and while supplying water to the water supply tank via the water supply passage, adjusting the water supply flow rate so as to maintain the outlet side water temperature of the condenser at a target temperature, and in the water supply tank The water supply heating system is characterized in that the target temperature is changed based on the water level .

According to the invention as set forth in claim 1, the water supply flow rate via the water supply passage is maintained so that the outlet side water temperature of the condenser is maintained at the target temperature as the water supply temperature constant control for the water supply to the water supply tank via the water supply passage. Adjust. Then, by changing the target temperature of the hot water outlet temperature constant control based on the water level in the water supply tank, it is possible to adjust the water temperature and the water amount in the water supply tank.
According to a second aspect of the present invention, the target temperature is changed so as to decrease stepwise or continuously as the water level in the water supply tank decreases, and gradually increases as the water level in the water supply tank increases. Alternatively, the water supply heating system according to claim 1, wherein the system is changed so as to continuously rise.
According to the second aspect of the invention, the hot water outlet temperature constant control is performed during the water supply via the water supply passage, but the lower the water level in the water supply tank, the lower the control target temperature (that is, the hot water outlet temperature). In the constant hot water temperature control, the flow rate can be increased as the target temperature is lowered. Therefore, by lowering the target temperature as the water level in the water supply tank is lowered, the flow rate to the water supply tank can be increased and the water level can be restored. . As a result, it is possible to prevent the relatively low temperature water from being supplied to the water supply tank via the makeup water passage, and prevent the water temperature in the water supply tank from decreasing.

According to a third aspect of the invention, before SL unless the water temperature in the water supply tank does not exceed the upper limit temperature, according to claim 1 or claims, characterized in that the target temperature and the temperature higher than the temperature of the water supply tank Item 2. The water supply heating system according to item 2 .

According to the invention described in claim 3, in the feedwater via feed water channel, performs the hot water temperature constant control, by the control target temperature (i.e. the hot water temperature) and a temperature higher than the temperature of the water in the water supply tank, It is possible to prevent the water temperature in the water supply tank from decreasing. However, when the water temperature in the water supply tank exceeds the upper limit temperature, by making the target temperature equal to or lower than the water temperature in the water supply tank, it is possible to prevent cavitation of the water supply pump from the water supply tank to the boiler or the like.

According to a fourth aspect of the present invention, a subcooler for exchanging heat between the water in the water supply passage upstream of the condenser and the refrigerant from the condenser to the expansion valve, and the upstream side of the subcooler. The feed water heating system according to any one of claims 1 to 3, further comprising a waste heat recovery heat exchanger that exchanges heat between the water in the water supply passage and the heat source fluid.
The present invention as described in claim 5, prior Symbol water supply to the water supply tank through the water supply path, the water level in the water supply tank begins to be below the water supply start level, higher water than the water supply start level Stopping when the water level exceeds the stop water level, the water supply to the water supply tank via the makeup water channel starts when the water level in the water supply tank is lower than the makeup water start water level lower than the water supply start water level, and the water supply start water level higher than is a water warming system according to any one of claims 1 to 4, characterized in that stop to exceed low makeup water stop level than the water stop level.

According to the invention described in claim 5 , by setting the water supply start water level, the water supply stop water level, the makeup water start water level, and the makeup water stop water level in a predetermined manner, the water supply via the water supply channel has priority over the water supply via the makeup water channel. You can do it .

  According to the water supply heating system of the present invention, it is possible to carry out a desired hot water outlet temperature constant control according to the situation in the water supply tank (specifically, the water temperature and / or the water level). In addition, it is possible to prevent a water temperature drop and a shortage of water storage in the water supply tank without causing cavitation in the water supply pump from the water supply tank to the boiler or the like.

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

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

  The water supply heating system 1 of the present embodiment is a system capable of heating the water supply to the water supply tank 3 of the boiler 2 with the heat pump 4, and the water supply tank 3 for storing the water supply to the boiler 2 and the water supply tank 3 to this water supply tank 3. A make-up water tank 5 for storing water supply, a heat pump 4 for heating the water supply from the make-up water tank 5 to the water supply tank 3, and a heat source water tank 6 for storing heat source water as a heat source of the heat pump 4 are provided.

  The boiler 2 is a steam boiler and heats the water supply from the water supply tank 3 into steam. The boiler 2 is typically adjusted in the amount of combustion so as to maintain a desired steam pressure. Further, in the boiler 2, a pump 7 for supplying water from the water supply tank 3 to the boiler 2 is controlled so as to maintain a desired water level in the can. The steam from the boiler 2 is sent to various types of steam using equipment (not shown), but drain (condensed water of steam) from the steam using equipment may be returned to the water supply tank 3. Alternatively, the drain from the steam using facility may be supplied to the heat source water tank 6.

  The water supply tank 3 is capable of supplying water from the makeup water tank 5 via the heat pump 4 via the water supply passage 8 and also via the makeup water passage 9 without via the heat pump 4. By controlling the operations of the water supply pump 10 provided in the water supply passage 8 and the makeup water pump 11 provided in the makeup water passage 9, the makeup water is supplied through one or both of the water supply passage 8 and the makeup water passage 9. Water can be supplied from the tank 5 to the water supply tank 3.

  In the present embodiment, the water supply pump 10 can change the drive frequency of the motor and thus the rotation speed by an inverter. By changing the rotation speed of the water supply pump 10, the water supply flow rate to the water supply tank 3 via the water supply passage 8 can be adjusted. On the other hand, the makeup water pump 11 is on / off controlled in this embodiment.

  The makeup water tank 5 stores the water supply to the water supply tank 3. As water supply to the makeup water tank 5, soft water is used in this embodiment. That is, the soft water from which the hardness component in the water has been removed by a water softening device (not shown) using a cation exchange resin or the like is supplied to and stored in the makeup water tank 5. By controlling the water supply from the water softening device based on the water level in the makeup water tank 5, the water level in the makeup water tank 5 is maintained as desired.

  The heat pump 4 is a vapor compression heat pump, and is composed of a compressor 12, a condenser 13, an expansion valve 14 and an evaporator 15 which are sequentially connected in an annular shape. Then, the compressor 12 compresses the gas refrigerant into high temperature and high pressure. Further, the condenser 13 condenses and liquefies the gas refrigerant from the compressor 12. Further, the expansion valve 14 lowers the pressure and temperature of the refrigerant by allowing the liquid refrigerant from the condenser 13 to pass through. Then, the evaporator 15 evaporates the refrigerant from the expansion valve 14.

  Therefore, in the heat pump 4, in the evaporator 15, the refrigerant takes heat from the outside to be vaporized, while in the condenser 13, the refrigerant radiates heat to the outside and is liquefied. Utilizing this, in the present embodiment, the heat pump 4 draws heat from the heat source water in the evaporator 15, and warms the water in the water supply passage 8 in the condenser 13.

  The heat pump 4 preferably further includes a subcooler 16 between the condenser 13 and the expansion valve 14. The subcooler 16 is an indirect heat exchanger between water in the water supply passage 8 on the upstream side of the condenser 13 and a refrigerant from the condenser 13 to the expansion valve 14. The subcooler 16 can supercool the refrigerant from the condenser 13 to the expansion valve 14 by supplying water to the condenser 13, and at the same time, the refrigerant from the condenser 13 to the expansion valve 14 to the condenser 13 The water supply can be heated. The refrigerant of the heat pump 4 preferably releases latent heat in the condenser 13 and sensible heat in the subcooler 16.

  In addition, in the heat pump 4, an accumulator is installed on the inlet side of the compressor 12, an oil separator is installed on the outlet side of the compressor 12, and an outlet side of the condenser 13 (the condenser 13 and the subcooler 16 You may install a receiver between (and).

  By the way, the heat pump 4 may be capable of changing its output. For example, the output of the heat pump 4 can be changed by changing the drive frequency of the motor of the compressor 12 and thus the number of revolutions with an inverter. However, in the following, an example in which the heat pump 4 is operated at a constant output while the drive frequency of the motor of the compressor 12 is maintained constant will be described.

  The feed water heating system 1 of this embodiment further includes a waste heat recovery heat exchanger 17. The waste heat recovery heat exchanger 17 is an indirect heat exchanger between the water in the water supply passage 8 on the upstream side of the subcooler 16 and the heat source water after passing through the evaporator 15. Therefore, the water supply from the makeup water tank 5 is sequentially passed through the water supply passage 8 to the waste heat recovery heat exchanger 17, the subcooler 16 and the condenser 13. On the other hand, the heat source water from the heat source water tank 6 is sequentially passed through the heat source supply passage 18 to the evaporator 15 and the waste heat recovery heat exchanger 17. Then, in the waste heat recovery heat exchanger 17, the water supply to the subcooler 16 can be heated by the heat source water that has passed through the evaporator 15.

  The heat source water tank 6 stores heat source water. The heat source water is, for example, waste hot water (warm water discharged from a factory or the like). The heat source water tank 6 is provided with a heat source water supply path 19 and an overflow path 20 for overflowing the heat source water above a predetermined level.

  As described above, the heat source water in the heat source water tank 6 is passed through the heat source supply passage 18 and then through the evaporator 15 and then through the waste heat recovery heat exchanger 17. The heat source supply passage 18 is provided with a heat source supply pump 21 on the upstream side of the evaporator 15. By operating this heat source supply pump 21, the heat source water from the heat source water tank 6 and the evaporator 15 are discarded. It can be passed through the heat recovery heat exchanger 17 in sequence.

  A water level detector 22 is provided in the water supply tank 3. The structure of the water level detector 22 is not particularly limited, but is an electrode type water level detector in the present embodiment. In this case, a plurality of electrode rods 23 to 28 having different lengths are inserted and held in the water supply tank 3 with different height positions of their lower ends. In this embodiment, in addition to the feed water start electrode rod 23 and feed water stop electrode rod 24 for controlling the feed water pump 10, the feed water start electrode rod 25 and make-up water stop electrode rod 26 for controlling the makeup water pump 11 feed water. It is inserted in the tank 3. Further, as will be described later in detail, one or a plurality of hot water outlet temperature switching electrode rods 27 and 28 are provided to switch the hot water outlet temperature via the water supply passage 8 as necessary. In the illustrated example, the first hot water outlet temperature switching electrode rod 27 and the second hot water outlet temperature switching electrode rod 28 are inserted into the water supply tank 3 with their lower end positions displaced from each other. In any case, the water supply stop electrode rod 24, the makeup water stop electrode rod 26, the water supply start electrode rod 23, and the makeup water start electrode rod 25 are inserted in the water supply tank 3 in the order of lowering the height position of the lower end. It When the tapping temperature switching electrode rods 27 and 28 are provided, the tapping temperature switching electrode rods 27 and 28 are provided at a height position between the lower end portion of the water supply starting electrode rod 23 and the lower end portion of the makeup water starting electrode rod 25. The lower end of is arranged.

  Each of the electrode rods 23 to 28 detects the presence or absence of the water level at the lower end portion depending on whether or not the lower end portion thereof is immersed in water. In the following, the water level detected by the water supply start electrode rod 23 is the water supply start water level H1, the water level detected by the water supply stop electrode rod 24 is the water supply stop water level H2, and the water level detected by the makeup water start electrode rod 25 is the makeup water start water level H3, The water level detected by the makeup water stop electrode rod 26 is the makeup water stop water level H4, the water level detected by the first tap water temperature switching electrode rod 27 is the water level detected by the first tap water temperature switching water level H5, and the second tap water temperature switching electrode rod 28. Is referred to as the second hot water temperature switching water level H6.

  The heat source water tank 6 is provided with a water level detector 29 in order to confirm the presence or absence of heat source water. The structure of the water level detector 29 is not particularly limited, but in this embodiment, it is an electrode type water level detector. In this case, the low water level detection electrode rod 30 is inserted into the heat source water tank 6, and it is monitored whether the water level of the heat source water is below the setting. Further, if desired, a heat source temperature sensor (not shown) may be provided in the heat source water tank 6 or the heat source supply path 18 (on the inlet side of the evaporator 15) to detect the temperature of the heat source water. When the water level of the heat source water tank 6 is below the setting, or when the temperature of the heat source water to the evaporator 15 is above the setting, the heat pump 4 can be stopped.

  A hot water outlet temperature sensor 31 is provided in the water supply passage 8 on the outlet side of the condenser 13. Hot water temperature sensor 31 detects the water temperature after passing through condenser 13. The water supply pump 10 is controlled based on the temperature detected by the hot water temperature sensor 31. Here, water supply pump 10 is inverter-controlled so as to maintain the temperature detected by tap water temperature sensor 31 at the target temperature during its operation (that is, during operation in relation to the water level in water supply tank 3). As a result, the flow rate of the water supplied to the water supply tank 3 via the water supply passage 8 is adjusted so that the temperature detected by the hot water outlet temperature sensor 31 is maintained at the target temperature.

  A water temperature sensor 32 is provided in the water supply tank 3. The stored water temperature sensor 32 detects the temperature of the stored water in the water supply tank 3. Considering that the water level in the water supply tank 3 fluctuates, the stored water temperature sensor 32 is provided at a position where it constantly contacts the stored water regardless of the fluctuation of the water level.

  Next, the control (operating method) of the water supply heating system 1 of this embodiment will be described. A series of controls described below is automatically performed by using a controller (not shown). That is, the controller includes the heat pump 4, the water supply pump 10, the makeup water pump 11, the heat source supply pump 21, the water level detector 22 of the water supply tank 3, the water level detector 29 of the heat source water tank 6, the hot water temperature sensor 31, and the stored water temperature. It is connected to the sensor 32 and the like and executes the following series of controls. Hereinafter, first, the basic control that is the premise of the characteristic control of the present invention will be described, and then the characteristic control of the present invention will be specifically described.

  The water supply to the water supply tank 3 is performed by controlling the water supply pump 10 and the makeup water pump 11 based on the detection signal of the water level detector 22 provided in the water supply tank 3. That is, the water supply to the water supply tank 3 via the water supply passage 8 starts when the water level in the water supply tank 3 falls below the water supply start water level H1, and stops when it exceeds the water supply stop water level H2 higher than this water supply start water level H1. .. Further, the water supply to the water supply tank 3 via the makeup water passage 9 starts when the water level in the water supply tank 3 falls below the makeup water start water level H3, and exceeds the makeup water stop water level H4 higher than this makeup water start water level H3. And stop. Here, the makeup water start water level H3 is set lower than the feed water start water level H1, and the makeup water stop water level H4 is set higher than the feed water start water level H1 but lower than the feed water stop water level H2.

  With such a configuration, if the water supply stop electrode rod 24 is now detecting the water level, it is determined that the water level in the water supply tank 3 is sufficient, and the water supply pump 10 is stopped and the makeup water pump 11 is also stopped. is doing. When the water level of the water supply tank 3 is lowered by the water supply from the water supply tank 3 to the boiler 2 and the water supply start electrode rod 23 no longer detects the water level, the water supply pump 10 is operated. As a result, water is supplied to the water supply tank 3 via the water supply passage 8, but when the water supply stop electrode rod 24 detects the water level, the water supply pump 10 is stopped. On the other hand, even if the water supply pump 10 is operated, the water level in the water supply tank 3 cannot be recovered, the water level in the water supply tank 3 further decreases, and the makeup water starting electrode rod 25 no longer detects the water level, the makeup water pump 11 also operates. Let As a result, water is supplied to the water supply tank 3 also through the makeup water channel 9, but when the water level in the water supply tank 3 is restored and the makeup water stop electrode rod 26 detects the water level, the makeup water pump 11 is stopped, and When the water level is restored and the water supply stop electrode rod 24 detects the water level, the water supply pump 10 is stopped. The water supply pump 10 is operated to supply water to the water supply tank 3 through the water supply passage 8 and the heat source supply pump 21 is also operated.

  In the present embodiment, the heat pump 4 operates during the water supply through the water supply passage 8 (with the passage of the heat source water through the heat source supply passage 18). However, as described above, the start / stop of the heat pump 4 is controlled based on the detection signals of the water level detector 29 provided in the heat source water tank 6 and the heat source temperature sensor provided in the heat source water tank 6 or the heat source supply path 18. Good. The heat pump 4 is switched between operation and stop depending on whether the compressor 12 is operating or not. During operation of the heat pump 4, the drive frequency of the motor of the compressor 12 is maintained constant, and a constant output is maintained.

  During operation, water supply pump 10 is inverter-controlled in rotation speed so as to maintain the temperature detected by hot water temperature sensor 31 at the target temperature (hot water temperature constant control). The target temperature for this constant heated water temperature control is changed according to the situation. That is, in the feed water heating system 1 of the present embodiment, the target temperature for the hot water outlet temperature constant control is changed based on the water temperature and / or the water level in the water supply tank 3. Specifically, (a) change control based on the water temperature in the water supply tank 3, (b) change control based on the water level in the water supply tank 3, or (c) change control based on the water temperature and the water level in the water supply tank 3. Done. Each of these controls will be described below.

<< (a) Change control based on the water temperature in the water supply tank 3 >>
The target temperature of the hot water discharge temperature constant control is changed based on the water temperature in the water supply tank 3. In this embodiment, the target temperature is set higher than the water temperature in the water supply tank 3 as long as the water temperature in the water supply tank 3 does not exceed the upper limit temperature. Specifically, the water temperature in the water supply tank 3 is monitored by the stored water temperature sensor 32 (for example, the water temperature in the water supply tank 3 is acquired every predetermined time) during the water supply through the water supply passage 8, and the stored water temperature sensor 32 is detected. As long as the detected temperature does not exceed the upper limit temperature, the target temperature is set to be higher than the detected temperature of the stored water temperature sensor 32, and the outlet heated water temperature constant control is performed.

  For example, as long as the water temperature in the water supply tank 3 does not exceed the upper limit temperature, the target temperature is set higher than the water temperature in the water supply tank 3 by a predetermined temperature. At this time, the predetermined temperature may be changed based on the water level in the water supply tank 3, for example, may be changed to a smaller value as the water level in the water supply tank 3 becomes lower.

  As a specific example, assuming that the upper limit temperature is 80 ° C. and the predetermined temperature is 10 ° C., if the water temperature in the water supply tank 3 is 80 ° C. or less, the value obtained by adding 10 ° C. to the water temperature in the water supply tank 3 is the target temperature. Then, the hot water outlet temperature constant control may be performed. For example, if the temperature detected by the stored water temperature sensor 32 is 40 ° C., the water supply pump 10 is inverter-controlled so that the temperature detected by the hot water supply temperature sensor 31 becomes 50 ° C. while the water supply pump 10 is operating, and the water supply passage is supplied. Adjust the feed water flow rate through 8. Further, if the temperature detected by the stored water temperature sensor 32 is 50 ° C., the water supply pump 10 is inverter-controlled so that the temperature detected by the hot water supply temperature sensor 31 is 60 ° C. during operation of the water supply pump 10, and the water supply channel is controlled. Adjust the feed water flow rate through 8. On the other hand, when the detected temperature of the stored water temperature sensor 32 exceeds the upper limit temperature of 80 ° C., the target temperature is set to the upper limit temperature (80 ° C.) or a temperature lower than the upper limit temperature (for example, 75 ° C.), It is advisable to carry out a constant discharge temperature control. Note that the upper limit temperature of 80 ° C. and the predetermined temperature of 10 ° C. described here are examples, and can be changed as appropriate. However, the upper limit temperature is set in a range that does not cause cavitation in the pump 7 for feeding water from the water supply tank 3 to the boiler 2.

  In this way, by setting the target temperature of the hot water outlet temperature constant control to be higher than the water temperature in the water supply tank 3, it is possible to prevent the water temperature in the water supply tank 3 from decreasing. However, when the water temperature in the water supply tank 3 exceeds the upper limit temperature, the cavitation of the pump 7 for water supply from the water supply tank 3 to the boiler 2 or the like is prevented by setting the target temperature to be equal to or lower than the water temperature in the water supply tank 3. can do.

  When the target temperature for constant hot water temperature control is changed and controlled based on the water temperature in water supply tank 3, water level detector 22 of water supply tank 3 does not need to detect hot water temperature switching water levels H5, H6. In other words, in FIG. 1, the installation of the tapping temperature switching electrode rods 27 and 28 can be omitted.

<< (b) Change control based on the water level in the water supply tank 3 >>
The target temperature for the hot water outlet temperature constant control is changed based on the water level in the water supply tank 3. In this embodiment, the lower the water level in the water supply tank 3 is, the lower the target temperature is made in steps or continuously. Specifically, the water level in the water supply tank 3 is monitored by the water level detector 22 during the water supply through the water supply passage 8, and the target temperature is lowered as the water level in the water supply tank 3 becomes lower, and the hot water outlet temperature constant control is performed. Carry out.

  In the present embodiment, when the water level in the water supply tank 3 falls below the water supply start water level, water supply via the water supply passage 8 is started, and at that time, hot water outlet temperature constant control is performed. Then, the target temperature of the outlet heated water temperature constant control is set to the first target temperature (for example, 90 ° C.). After that, when the temperature falls below the first hot water temperature switching water level H5, the target temperature is changed to a second target temperature (for example, 75 ° C.) lower than the first target temperature. In the constant tap water temperature control, the flow rate can be increased as the target temperature is lowered.

  By performing the hot water outlet temperature constant control at the second target temperature, the water level is restored, and if the water supply start water level H1 is exceeded, the target temperature is returned to the first target temperature, and if the water supply stop water level H2 is exceeded, Stop water supply. On the other hand, even if the hot water outlet temperature constant control is performed at the second target temperature, if the water level in the water supply tank 3 does not recover and the water level further decreases and falls below the second hot water temperature switching water level H6, the target temperature Change to a third target temperature (eg, 55 ° C.) lower than the second target temperature. As a result, if the water level is restored and exceeds the first hot water temperature switching water level H5, the target temperature is returned to the second target temperature, and if it exceeds the water supply start water level H1, the target temperature is returned to the first target temperature and the water supply stop water level H2 is reached. If it exceeds, the water supply will be stopped.

  Here, an example in which the target temperature is switched in three stages of the water supply start water level H1, the first hot water temperature switching water level H5, and the second hot water temperature switching water level H6 has been described, but it is possible to appropriately change how many stages are switched. Is. Further, if the target temperature is lowered as the water level in the water supply tank 3 becomes lower, how many times the target temperature at each stage is set can be appropriately changed.

  For example, in FIG. 1, the setting of the second hot water outlet temperature switching electrode rod 28 may be omitted, and the target temperature may be switched in two stages of the first target temperature and the second target temperature. Alternatively, in FIG. 1, a third hot water temperature switching electrode rod is added between the second hot water temperature switching water level H6 and the makeup water start water level H3 so as to detect the third hot water temperature switching water level. The temperature may be switched. Further, as will be described later, when a water level sensor capable of continuously detecting the water level in the water supply tank 3 is used, control is performed so as to lower the target temperature continuously or at each set height as the water level in the water supply tank 3 decreases. You may.

  In this way, the target temperature for the hot water outlet temperature constant control can be lowered as the water level in the water supply tank 3 becomes lower. In the constant hot water temperature control, the flow rate can be increased as the target temperature is lowered. Therefore, by lowering the target temperature as the water level in the water supply tank 3 is lowered, the flow rate to the water supply tank 3 is increased and the water level is restored. You can As a result, it is possible to prevent the relatively low temperature water (normal temperature water) from being supplied to the water supply tank 3 via the makeup water passage 9, and to prevent the water temperature in the water supply tank 3 from decreasing.

  By the way, lowering the target temperature of the constant heated water temperature control has the following merits. First, as a premise, it is assumed that the heat source water temperature on the inlet side of the evaporator 15 is constant, and the water temperature (the target temperature) on the outlet side of the condenser 13 is higher than the heat source water temperature on the inlet side of the evaporator 15. In this case, the smaller the temperature difference between the water temperature on the outlet side of the condenser 13 and the heat source water temperature on the inlet side of the evaporator 15 (that is, the smaller the temperature difference to be pumped up), the smaller the power consumption of the compressor 12 and the improved COP. To do. Therefore, lowering the target temperature of the hot water outlet temperature constant control allows the feed water heating system 1 to be operated with energy saving. Further, if the target temperature is lowered, the water flow rate can be increased, and as a result, the heating amount of the feed water in the waste heat recovery heat exchanger 17 can be increased. Therefore, also from this point, lowering the target temperature for the constant hot water outlet temperature control enables the feed water heating system 1 to be operated with energy saving.

<< (c) Change control based on water temperature and water level in water supply tank 3 >>
The target temperature of the hot water outlet temperature constant control is changed based on the water temperature and the water level in the water supply tank 3. In this case, the controls (a) and (b) may be combined. That is, basically, as described in (b) above, the target temperature for the constant hot water outlet temperature control is changed according to the water level. For example, if the water temperature falls below the water supply start water level H1, the hot water is discharged at the first target temperature (for example 90 ° C.), and if it falls below the first hot water temperature switching water level H5, the hot water is switched to the second hot water temperature (for example 75 ° C.), When the temperature falls below the hot water temperature switching water level H6, the hot water may be switched to the third hot water temperature (for example, 55 ° C.). Of course, as described in (b) above, the target temperature may be switched at two levels of water level, the target temperature may be switched at three or more levels of water level, or the target temperature may be switched continuously. Good.

  Then, in order to change the target temperature not only by the water level in the water supply tank 3 but also by the water temperature, the hot water outlet temperature may be limited according to the water temperature in the water supply tank 3. That is, as described in (a) above, the target temperature may be higher than the water temperature in the water supply tank 3 as long as the water temperature in the water supply tank 3 does not exceed the upper limit temperature. For example, when the water level in the water supply tank 3 is lower than the second hot water temperature switching water level H6, the water temperature in the water supply tank 3 is 65% although it is essentially to switch to the third target temperature (for example, 55 ° C.) in the above example. If the temperature is ° C, the second target temperature (for example, 75 ° C) is maintained.

  In this way, basically, the target temperature for the hot water outlet temperature constant control is set based on the water level in the water supply tank 3, but if the water temperature in the water supply tank 3 is higher than the target temperature (target temperature depending on the water level). The target temperature is preferably higher than the water temperature in the water supply tank 3. At that time, the target temperature may be a temperature obtained by adding a predetermined temperature to the water temperature in the water supply tank 3, or the target temperature may be set stepwise from the water level (first target temperature to third target temperature). A temperature higher than the water temperature in the tank 3 may be adopted. However, as described in (a) above, when the water temperature in the water supply tank 3 exceeds the upper limit temperature, it is preferable to set the target temperature below the upper limit temperature.

  The water supply heating system 1 of the present invention is not limited to the configuration of the above embodiment, but can be modified as appropriate. In particular, in the water supply warming system 1 including the heat pump 4 and the water supply tank 3, the water supply flow rate is adjusted so that the water temperature of the outlet side of the condenser 13 is maintained at the target temperature during the water supply to the water supply tank 3 via the heat pump 4. Other configurations and controls can be appropriately changed as long as they are adjusted and the target temperature is changed based on the water temperature and / or the water level in the water supply tank 3.

  For example, in the above embodiment, the installation of one or both of the subcooler 16 and the waste heat recovery heat exchanger 17 may be omitted.

  Further, in the above embodiment, the makeup water stop water level H4 and the water supply start water level H1 may be replaced with each other. That is, the water supply stop electrode rod 24, the water supply start electrode rod 23, the makeup water stop electrode rod 26, and the makeup water start electrode rod 25 may be inserted in the water supply tank 3 in the order of lowering the height position of the lower end. ..

  Further, in the above embodiment, the electrode type water level detector is used as the water level detector 22 of the water supply tank 3, but an analog type water level detector capable of obtaining a continuous output according to the water level may be used. Specifically, a water pressure type water level detector that utilizes the fact that the water pressure changes depending on the water level in the water supply tank 3 can be used, but a pressure sensor can also be used instead. Alternatively, a capacitance type water level detector may be used. In any case, the same control as that of the above-described embodiment can be performed.

  Further, in the above-described embodiment, the water supply pump 10 is inverter-controlled in order to adjust the water supply flow rate to the water supply tank 3 via the water supply passage 8. However, the water supply pump 10 is provided in the water supply passage 8 while controlling the on / off of the water supply pump 10. The opening of the valve may be adjusted. That is, if the flow rate of the water supply via the water supply passage 8 can be adjusted based on the temperature detected by the hot water temperature sensor 31, etc., the flow rate adjusting method can be appropriately changed.

  Further, in the case of the above-described embodiment, if water can be supplied to the water supply tank 3 by the water supply passage 8 via the condenser 13 and water can be supplied by the makeup water passage 9 without passing through the condenser 13, the water supply passage 8 or The specific configuration of the makeup water channel 9 is not limited to the configuration of the above-described embodiment, and can be changed as appropriate. For example, in the above-described embodiment, the water supply passage 8 and the makeup water passage 9 are provided in parallel so as to connect the makeup water tank 5 and the makeup water tank 3, respectively, but one end portion of the water supply passage 8 and the makeup water passage 9 ( One or both of the makeup water tank 5 side end) and the other end (water supply tank 3 side end) may be a common conduit. In other words, one end of the makeup water channel 9 may be provided so as to branch from the water supply channel 8 instead of being connected to the makeup water tank 5, and the other end of the makeup water channel 9 may be connected to the water tank 3. Instead of doing so, it may be provided so as to join the water supply passage 8 before the water supply tank 3. When one end of the makeup water passage 9 is provided so as to branch from the water supply passage 8 instead of being connected to the makeup water tank 5, a water supply pump 10 is provided in the water supply passage 8 downstream from the branch portion while the makeup water passage 8 is provided. 9 may be provided with a makeup water pump 11, but a pump may be provided only in the common pipe line upstream of the branch portion to open / close and open the valves provided in the water supply passage 8 and the makeup water passage 9 downstream of the branch portion. By adjusting the degree, the presence or absence of water flow to the water supply channel 8 or the makeup water channel 9 and the flow rate may be adjusted.

  Further, in the above-described embodiment, the makeup water tank 5 is installed to store the water supply to the water supply tank 3, but the installation of the makeup water tank 5 may be omitted in some cases, and the water supply passage 8 and the makeup water may be directly supplied from the water supply source. Water may be passed through the waterway 9.

  Further, in the above-described embodiment, it is possible to supply water from the makeup water tank 5 to the water supply tank 3 via the water supply passage 8 and / or the makeup water passage 9, but such water supply may be performed directly from the water softening device. For example, in FIG. 1, the base end portions of the water supply channel 8 and the makeup water channel 9 are collectively connected to the water softening device, and instead of omitting the installation of the water supply pump 10, the electric valve (motor valve) provided in the water channel 8 is replaced. Instead of omitting the installation of the makeup water pump 11 by adjusting the opening degree, the opening / closing of the solenoid valve provided in the makeup water passage 9 may be controlled.

  Further, in the above-mentioned embodiment, the system in which the water supply to the water supply tank 3 of the boiler 2 can be heated by the heat pump 4 has been described, but the use destination of the stored water in the water supply tank 3 is not limited to the boiler 2 and can be appropriately changed. is there.

  Further, in the above-described embodiment, the example in which the heat source water is used as the heat source of the heat pump 4 has been described, but the heat source fluid of the heat pump 4 is not limited to the heat source water, and various fluids such as air and exhaust gas can be used.

  Further, in the above-described embodiment, when the heat pump 4 is operated, the drive frequency of the motor of the compressor 12 is maintained constant, but in some cases, the discharge pressure of the compressor 12 may be controlled to be maintained at a predetermined value. .. Alternatively, the output of the compressor 12 may be adjusted based on the temperature of the heat source fluid to the evaporator 15.

  Further, the heat pump 4 is not limited to a single stage, but may have a plurality of stages. When the heat pump 4 has a plurality of stages, the heat pumps of the adjacent stages may be connected to each other using an indirect heat exchanger or a direct heat exchanger (intercooler). In the latter case, the refrigerant from the compressor of the low-stage heat pump and the refrigerant from the expansion valve of the high-stage heat pump are received, and an intermediate cooler that directly contacts the two refrigerants to exchange heat is provided, and this intermediate cooler is It is a condenser for a low-stage heat pump and an evaporator for a high-stage heat pump. As described above, the multi-stage (multi-stage) heat pump includes a multi-source (multi-source) heat pump, or a combination of these heat pumps, in addition to the single-source multi-stage heat pump.

  Further, in the above embodiment, the compressor 12 of the heat pump 4 was driven by the electric motor, but the drive source of the compressor 12 is not particularly limited. For example, the compressor 12 may be driven by a steam motor (steam engine) that uses steam to generate power, or by a gas engine, instead of or in addition to the electric motor.

1 Water Supply Heating System 2 Boiler 3 Water Supply Tank 4 Heat Pump 5 Makeup Water Tank 6 Heat Source Water Tank 7 Pump 8 Water Supply Channel 9 Makeup Water Channel 10 Water Supply Pump 11 Makeup Water Pump 12 Compressor 13 Condenser 14 Expansion Valve 15 Evaporator 16 Supercooling 17 Waste heat recovery heat exchanger 18 Heat source supply path 19 Heat source water supply path 20 Overflow path 21 Heat source supply pump 22 Water level detector 23 Water supply starting electrode rod 24 Water supply stopping electrode rod 25 Makeup water starting electrode rod 26 Makeup water stopping electrode Rod 27 1st hot water temperature switching electrode rod 28 2nd hot water temperature switching electrode rod 29 Water level detector 30 Low water level detection electrode rod 31 Hot water temperature sensor 32 Reservoir temperature sensor H1 Water supply start water level H2 Water supply stop water level H3 Makeup water start water level H4 Makeup water stop water level H5 First hot water temperature switching water level H6 Second hot water temperature switching water level

Claims (5)

A compressor, a condenser, an expansion valve and an evaporator are sequentially connected in an annular shape to circulate a refrigerant, draw up heat from a heat source fluid passed through the evaporator, and heat the water passed through the condenser. When,
It is possible to supply water by a water supply channel via the condenser, and a water supply tank capable of supplying water by a makeup water channel without passing through the condenser,
Water supply to the water supply tank via the water supply passage, adjusting the water supply flow rate so as to maintain the outlet side water temperature of the condenser at a target temperature,
A water supply heating system, wherein the target temperature is changed based on a water level in the water supply tank. The target temperature is changed such that the lower the water level in the water supply tank, the more gradually or continuously the temperature lowers, and the higher the water level in the water supply tank, the more gradually or continuously the temperature rises. Ru
The water supply heating system according to claim 1, characterized in that. As long as the water temperature before Symbol water tank does not exceed the upper limit temperature, water warming system of claim 1 or claim 2, characterized in that the target temperature and the temperature higher than the temperature of the water supply tank . Water in the water supply passage upstream of the condenser, and a subcooler for exchanging heat with the refrigerant from the condenser to the expansion valve,
A waste heat recovery heat exchanger for exchanging heat between the water in the water supply passage upstream of the subcooler and the heat source fluid is further provided.
The water supply heating system according to any one of claims 1 to 3, which is characterized in that. Water supply to the water supply tank through a pre-Symbol water supply passage, the water level in the water supply tank begins to be below the water supply start level, and stops when above the water stop level higher than the water supply start level,
Water supply to the water supply tank via the makeup water passage starts when the water level in the water supply tank is lower than the makeup water start water level lower than the water supply start water level, and is higher than the water supply start water level but the water supply stop water level. The supply water heating system according to any one of claims 1 to 4, wherein the supply water warming system is stopped when the water level is lower than the makeup water stop water level that is lower than that.

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