JP2015081708A - Water supply heating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve easy water level control in a water supply heating system including a plurality of units of heat pumps.SOLUTION: In a water supply tank 3, water is supplied via a plurality of water supply passages 9 at least one part of which are in parallel. A heat pump 4 provided at each water supply passage 9 heats the water supply to the water supply tank 3. A water level detector of the water supply tank 3 detects a plurality of setting water levels which are different gradually in the water supply tank 3. Every time the water level in the water supply tank 3 becomes lower than each setting water level, the number of the heat pumps 4 in which water is passed is increased, and on the other hand, every time the water level in the water supply tank 3 becomes higher than each setting water level continuously for preset time, the number of the heat pumps 4 in which water is passed is decreased.

Description

  The present invention relates to a feed water warming system using a heat pump, and particularly to a feed water warming system including a plurality of heat pumps.

  Conventionally, as disclosed in Patent Document 1 below, a system capable of heating water supplied to a water supply tank (23) of a boiler (24) using a heat pump (12) is known. Further, as disclosed in Patent Document 2 below, a highly efficient feed water heating system is also known by including a waste heat recovery heat exchanger (12) and a supercooler (17).

  In this type of feed water warming system, there are cases where it is desired to install a plurality of heat pumps in order to increase the hot water supply capacity. However, if the plurality of heat pumps are simultaneously started and stopped, the flow rate difference between the simultaneous operation of the plurality of units and the simultaneous stop of the plurality of units becomes large, so that it is difficult to control the water level in the water supply tank.

JP 2010-25431 A (FIGS. 2 and 3) Japanese Patent No. 5263421

  Therefore, the problem to be solved by the present invention is to realize easy water level control in a feed water warming system including a plurality of heat pumps.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is characterized in that a water supply tank supplied with water through a plurality of water supply paths that are at least partially in parallel, and each of the water supply paths is provided. A heat pump for heating the water supply to the water supply tank, a water level detector for detecting a plurality of different set water levels in the water supply tank, and the water supply tank based on the detection signal of the water level detector And a controller for increasing the number of heat pumps to be passed each time the water level inside the water level falls below each of the set water levels.

  According to the first aspect of the present invention, a plurality of set water levels that differ in stages in the water supply tank are detected, and the number of heat pumps that pass water is reduced each time the water level in the water supply tank falls below each set water level. increase. Therefore, as the water level in the water supply tank decreases, the water supply flow rate can be increased. However, when the water level in the water supply tank is relatively high, the water supply flow rate is suppressed to a relatively small amount. In this way, easy water level control can be realized.

The invention according to claim 2 is the feed water heating system according to claim 1, wherein any one of the following (a) to (c) is executed based on a detection signal of the water level detector. .
(A) Each time the water level in the water supply tank falls below the set water level, the number of the heat pumps to be passed is increased, while the water level in the water tank continuously exceeds the set water level for a set time. Each time, the number of the heat pumps to be passed is reduced.
(B) Each time the water level in the water supply tank falls below the set water levels for a set time, the number of the heat pumps to be passed is increased, while the water level in the water tank exceeds the set water levels. Each time, the number of the heat pumps to be passed is reduced.
(C) Each time the water level in the water supply tank falls below the set water levels for a set time, the number of the heat pumps to be passed is increased, while the water level in the water tank sets the set water levels. Each time the time is exceeded, the number of the heat pumps to be passed is reduced.

  According to the second aspect of the present invention, a plurality of different set water levels in the water supply tank are detected in stages, and the number of heat pumps to be passed is sequentially increased or conversely decreased. be able to. Therefore, the water supply flow rate can be increased as the water level in the water supply tank decreases, and the water supply flow rate can be decreased as the water level in the water supply tank increases. In this way, easy water level control can be realized. Moreover, even when such control is performed by an electrode-type water level detector, it is not necessary to install separate electrode rods for the water supply start water level and the water supply stop water level, so the configuration is simple even when the number of heat pumps increases. It is.

  According to a third aspect of the present invention, the water supply tank can be supplied with water through a heat supply channel via the heat pump, and can be supplied with a replenishment water channel without using the heat pump, and the water supply tank can be supplied with the water through the supply water channel. Water supply to the water supply tank starts when the water level in the water supply tank falls below a makeup water start water level lower than the lowest set water level of the plurality of set water levels, while replenishment higher than the makeup water start water level The feed water warming system according to claim 2, wherein the water supply warming system stops when the water stop water level is exceeded.

  According to the third aspect of the present invention, when the water level in the water supply tank cannot be maintained as desired only by water supply from the water supply path via the heat pump, water supply is also performed from the supply water path not via the heat pump. It is possible to prevent the water level in the tank from dropping too much.

  The invention according to claim 4 is the feed water heating system according to claim 3, wherein the makeup water stop water level is higher than an uppermost set water level among the plurality of set water levels.

  According to the invention described in claim 4, the makeup water stop water level is set higher than the uppermost set water level among the plurality of set water levels for water supply control. That is, since the makeup water stop water level is relatively high as compared with the prior art (Patent Document 1), the water supply speed to the water supply tank can be increased, and a relatively large amount of water can be stored in the water supply tank. Therefore, there is no possibility that the amount of water stored in the water supply tank will be insufficient, and priority can be given to the operation of the most important boiler and its steam-using equipment.

In the invention according to claim 5, the water supply tank can be supplied with water through the heat pump and through the supply water channel, and can be supplied through the replenishment water channel without using the heat pump. The water supply warming system according to claim 2, wherein water supply to the water supply tank is controlled by any one of the following (a) to (c).
(A) Water supply to the water supply tank via the makeup water channel starts when the water level in the water supply tank falls below a predetermined water level lower than the lowest set water level of the plurality of set water levels, It stops when it exceeds the predetermined water level for a predetermined time.
(B) When water is supplied to the water supply tank via the makeup water channel, the water level in the water supply tank is continuously lower than a predetermined water level lower than a lowermost set water level among the plurality of set water levels for a predetermined time. On the other hand, it stops when it exceeds the predetermined water level.
(C) When supplying water to the water supply tank via the makeup water channel, the water level in the water supply tank continuously falls below a predetermined water level lower than a lowermost set water level among the plurality of set water levels for a predetermined time. On the other hand, it stops when it exceeds the predetermined water level for a predetermined time.

  According to the fifth aspect of the present invention, when the water level in the water supply tank cannot be maintained as desired only by water supply from the water supply channel via the heat pump, the water supply is also performed by supplying water from the supply water channel not via the heat pump. It is possible to prevent the water level in the tank from dropping too much. In addition, even when such control is performed by the electrode-type water level detector, it is not necessary to separately install the electrode rods at the makeup water start water level and the makeup water stop water level, so the configuration is simple.

  According to a sixth aspect of the present invention, each of the water supply channels is provided with a heating unit including the heat pump, and each of the heating units includes water in the water supply channel upstream of the condenser and a condenser. A subcooler for exchanging heat with the refrigerant from the expansion valve to the expansion valve, and a waste heat recovery heat exchanger for exchanging heat between the water in the water supply channel upstream of the subcooler and the heat source fluid after passing through the evaporator And adjusting the water supply flow rate to the water supply tank via the water supply path so as to maintain the outlet water temperature of the condenser at a target temperature during water supply to the water supply tank via the water supply path It is a feed water heating system of any one of Claims 1-5 characterized by the above-mentioned.

  According to the sixth aspect of the present invention, in each heating unit, water supplied to the water supply tank via the water supply passage is sequentially passed through the waste heat recovery heat exchanger, the subcooler, and the condenser. The heat source fluid is sequentially passed through an evaporator and a waste heat recovery heat exchanger. The efficiency of the heat pump can be improved by preheating the feed water to the condenser using the waste heat of the heat source fluid after passing through the evaporator and the heat of the refrigerant after passing through the condenser. In addition, the water temperature of the water supply source can be adjusted by adjusting the water supply flow rate to the water supply tank via the water supply channel so that the water temperature on the outlet side of the condenser is maintained at the target temperature during water supply to the water supply tank via the water supply channel. Regardless of the temperature of the heat source fluid, hot water having a desired temperature can be obtained.

  Furthermore, in the invention according to claim 7, each heating unit causes the heat pump to turn on when the heat source fluid temperature to the evaporator becomes equal to or higher than a set temperature during water supply to the water supply tank via the water supply channel. The water supply warming system according to claim 6, wherein water is supplied to the water supply tank through the water supply channel in a stopped state.

  According to the seventh aspect of the invention, in each heating unit, when the heat source fluid temperature to the evaporator becomes equal to or higher than the set temperature, the heat pump is stopped, so that the compressor can be protected. However, even in that case, heat recovery from the heat source fluid can be achieved by exchanging heat between the water supply and the heat source fluid in the waste heat recovery heat exchanger.

  According to the present invention, easy water level control can be realized in a feed water warming system including a plurality of heat pumps.

It is the schematic which shows one Example of the feed water heating system of this invention. It is the schematic which shows one of the some heating units shown by FIG. It is the schematic which shows the specific structure of the water supply tank shown by FIG.

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

  The feed water warming system 1 of the present embodiment is a system that can heat the feed water to the feed water tank 3 of the boiler 2 by a heating unit 5 having a heat pump 4, and the feed water tank 3 that stores the feed water to the boiler 2. A replenishment water tank 6 for storing water supply to the water supply tank 3, a plurality of heating units 5 for heating water supplied from the replenishment water tank 6 to the water supply tank 3, And a heat source water tank 7 for storing heat source water (for example, waste warm water) as a heat source.

  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. Alternatively, drain from the steam using facility may be supplied to the heat source water tank 7.

  The water supply tank 3 can be supplied with water from the make-up water tank 6 through the water supply channel 9 via the heating unit 5 and can be supplied through the supply water channel 10 without using the heating unit 5. The water supply path 9 from the makeup water tank 6 to the water supply tank 3 is at least partially configured in parallel. Specifically, the make-up water tank 6 and the water supply tank 3 are basically connected by a plurality of water supply passages 9 arranged in parallel, but as shown in the illustrated example, the make-up water tank 6 side and the water supply tank 3 side Both or one of them may be configured as a common conduit.

  Anyway, the heating unit 5 is provided in each water supply path 9 arrange | positioned in parallel. The number of the water supply channels 9 arranged in parallel, in other words, the number of the heating units 5 is not particularly limited as long as it is plural, and is four in the illustrated example, but is two, three, or five or more. There may be. The configuration of each heating unit 5 is typically the same as each other.

  The presence or absence of water supply to the water supply tank 3 via each water supply path 9, in other words, the presence or absence of water flow of each heating unit 5 is controlled by a water supply pump 11 provided in each water supply path 9. On the other hand, whether or not water is supplied to the water supply tank 3 via the makeup water channel 10 is controlled by a makeup water pump 12 provided in the makeup water channel 10. In the illustrated example, the water supply pump 11 is provided outside the heating unit 5, but may be provided inside the heating unit 5 in some cases. That is, the heating unit 5 may include the water supply pump 11.

  In this embodiment, the feed pump 11 provided in each feed channel 9 can control the rotation speed by an inverter. By changing the rotation speed of each water supply pump 11, the water supply flow rate to the water supply tank 3 via each 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.

  FIG. 2 is a schematic diagram showing one of the plurality of heating units 5 shown in FIG. As shown in this figure, the heating unit 5 includes a heat pump 4 as a main part.

  The heat pump 4 is a vapor compression heat pump, and is configured by sequentially connecting a compressor 13, a condenser 14, an expansion valve 15, and an evaporator 16 in an annular shape. The compressor 13 compresses the gas refrigerant to a high temperature and a high pressure. The condenser 14 condenses and liquefies the gas refrigerant from the compressor 13. Further, the expansion valve 15 allows the liquid refrigerant from the condenser 14 to pass through, thereby reducing the pressure and temperature of the refrigerant. The evaporator 16 then evaporates the refrigerant from the expansion valve 15.

  Therefore, in the heat pump 4, in the evaporator 16, the refrigerant takes heat from the outside and vaporizes, while in the condenser 14, the refrigerant dissipates heat to the outside and condenses. Using this, in this embodiment, the heat pump 4 draws heat from the heat source water in the evaporator 16, and heats the water in the water supply passage 9 in the condenser 14.

  It is preferable that the heat pump 4 further includes a supercooler 17 between the condenser 14 and the expansion valve 15. The supercooler 17 is an indirect heat exchanger between the water in the water supply passage 9 upstream from the condenser 14 and the refrigerant from the condenser 14 to the expansion valve 15. The subcooler 17 can supercool the refrigerant from the condenser 14 to the expansion valve 15 by supplying water to the condenser 14, and can supply the refrigerant to the condenser 14 by the refrigerant from the condenser 14 to the expansion valve 15. The water supply can be heated. The refrigerant of the heat pump 4 preferably releases latent heat in the condenser 14 and releases sensible heat in the subcooler 17.

  That is, in the condenser 14, the gas refrigerant is condensed into a liquid refrigerant, and the liquid refrigerant is supplied to the subcooler 17, and the liquid refrigerant is further cooled (supercooled) in the subcooler 17. By separating heat exchangers for refrigerant condensation and supercooling, the heat exchanger can be easily designed, the heat exchanger can be reduced in size with a simple structure, and costs can be reduced. In addition, a general-purpose heat exchanger can be used.

  In addition, in the heat pump 4, an accumulator is installed on the inlet side of the compressor 13, an oil separator is installed on the outlet side of the compressor 13, or the outlet side of the condenser 14 (the condenser 14 and the subcooler 17 A receiver may be installed between the two).

  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 power supply frequency of the motor of the compressor 13 and hence the rotational speed with an inverter. However, in the following, an example in which the heat pump 4 is operated at a constant output while the power frequency of the motor of the compressor 13 is maintained constant will be described.

  In the present embodiment, each heating unit 5 further includes a waste heat recovery heat exchanger 18. This waste heat recovery heat exchanger 18 is an indirect heat exchanger between the water in the water supply channel 9 upstream of the subcooler 17 and the heat source water after passing through the evaporator 16. Therefore, in each heating unit 5, the water in the water supply passage 9 is passed through the waste heat recovery heat exchanger 18, the subcooler 17, and the condenser 14 in order. On the other hand, in each heating unit 5, the heat source water from the heat source water tank 7 is passed through the evaporator 16 and then passed to the waste heat recovery heat exchanger 18.

  As shown in FIG. 1, heat source water from the heat source water tank 7 can be supplied to each heating unit 5 via a heat source supply path 19. At this time, the heat source water from the heat source water tank 7 can be supplied to each heating unit 5 in parallel.

  The heat source water tank 7 stores heat source water as a heat source of the heat pump 4. The heat source water is, for example, waste hot water (hot water discharged from a factory or the like). The heat source water tank 7 is provided with a heat source water supply path 20 and an overflow path 21 for overflowing a predetermined amount or more of water.

  The heat source water in the heat source water tank 7 is supplied to each heating unit 5 through each heat source supply path 19, and after passing through the evaporator 16 of the heat pump 4 in each heating unit 5, waste heat recovery heat exchange is performed. Is passed through the vessel 18 (FIG. 2). Each heat source supply path 19 is provided with a heat source supply pump 22 on the upstream side of the evaporator 16, and by operating this heat source supply pump 22, the heat source water from the heat source water tank 7 is supplied to the heat source supply pump 22. 22 can be sequentially passed through an evaporator 16 and a waste heat recovery heat exchanger 18 provided downstream of the heat exchanger 22.

  By passing the heat source water through the waste heat recovery heat exchanger 18 after passing the evaporator 16 first, compared with the case where the heat source water is passed through the evaporator 16 after passing the waste heat recovery heat exchanger 18 first. Further, the evaporation temperature (that is, the evaporation pressure) of the refrigerant in the evaporator 16 can be increased, the pressure ratio of the compressor 13 can be reduced, and energy saving can be achieved.

  In the illustrated example, the heat source supply pump 22 is provided outside the heating unit 5, but may be provided inside the heating unit 5 in some cases. That is, the heating unit 5 may include the heat source supply pump 22.

  FIG. 3 is a schematic diagram showing a specific configuration of the water supply tank 3 shown in FIG. As shown in this figure, the water supply tank 3 is provided with a water level detector 23. The configuration of the water level detector 23 is not particularly limited. In the present embodiment, the water level detector 23 is an electrode type water level detector. In this case, a plurality of electrode rods 24 to 26 having different lengths are inserted and held in the water supply tank 3 with their lower end portions having different height positions. In this embodiment, a plurality of water supply control electrode rods 24 for controlling each water supply pump 11 (corresponding to the number of heating units 5 and four in the illustrated example), as well as makeup water for controlling the makeup water pump 12. A start electrode rod 25 and a makeup water stop electrode rod 26 are inserted into the water supply tank 3. At this time, as will be described in detail later, each of the water supply control electrode rods 24 is inserted into the water supply tank 3 so that the height position of the lower end thereof is lowered at a set interval (typically a constant interval). Further, the replenishment water stop electrode rod 26, the respective water supply control electrode rods 24, and the replenishment water start electrode rod 25 are inserted into the water supply tank 3 with the lower end of the height position lowered.

  Each electrode rod 24-26 detects the presence or absence of the water level in a lower end part by whether the lower end part is immersed in water. In the following, the water level detected by each of the water supply control electrode rods 24 is detected in stages, and the water level detected by the makeup water start electrode rod 25 is detected by the makeup water start water level H2 and the makeup water stop electrode rod 26. The water level is referred to as a makeup water stop water level H3.

  As shown in FIG. 1, the heat source water tank 7 is provided with a water level detector 27 in order to confirm the presence or absence of the heat source water. The configuration of the water level detector 27 is not particularly limited. In the present embodiment, the water level detector 27 is an electrode type water level detector. In this case, the low water level detection electrode rod 28 is inserted into the heat source water tank 7 to monitor whether the water level of the heat source water is lower than the setting.

  As shown in FIG. 2, each heating unit 5 is provided with a hot water temperature sensor 29 in the water supply passage 9 on the outlet side of the condenser 14. The tapping temperature sensor 29 detects the water temperature after passing through the condenser 14. In each heating unit 5, the water supply pump 11 to the heating unit 5 is controlled based on the temperature detected by the hot water temperature sensor 29. Here, the feed water pump 11 is inverter-controlled so as to maintain the temperature detected by the tapping temperature sensor 29 at the target temperature. Thus, the flow rate of water supplied to the water supply tank 3 via each water supply channel 9 is adjusted so that the temperature detected by the tapping water temperature sensor 29 provided in the water supply channel 9 is maintained at the target temperature.

  Each heating unit 5 is provided with a heat source temperature sensor 30 in the heat source supply path 19 on the inlet side of the evaporator 16. The heat source temperature sensor 30 detects the temperature of the heat source water supplied to the evaporator 16. However, the heat source temperature sensor 30 may be provided in the heat source water tank 7 depending on circumstances, and branches to a plurality of heat source supply paths 19 in order to supply heat source water from the heat source water tank 7 to each heating unit 5. You may provide in the common pipe line by the side of the front heat source water tank 7. FIG. Although details will be described later, based on the temperature detected by the heat source temperature sensor 30, the heat pump 4 (more specifically, the compressor 13) can be started and stopped and the target temperature can be changed.

  Next, control (operation method) of the feed water heating system 1 of the present embodiment will be described. A series of control described below is automatically performed using a controller (not shown).

  Water is supplied to the water supply tank 3 by controlling each of the water supply pumps 11 and the makeup water pump 12 based on a detection signal of a water level detector 23 provided in the water supply tank 3. Water supply control to the water supply tank 3 via each water supply path 9 is performed by any one of the following (a) to (c) based on the detection signal of the water level detector 23. The set water level H1 is a water level detected by the lower end of each water supply control electrode rod 24, and there are a plurality of water levels separated from each other in the vertical direction.

(A) Each time the water level in the water supply tank 3 falls below each set water level H1, the number of heating units 5 to be passed is increased, while the water level in the water supply tank 3 continues each set water level H1 for a set time. The number of heating units 5 that are passed through is reduced every time the temperature is exceeded.

(B) Each time the water level in the water supply tank 3 falls below each set water level H1 for a set time, the number of heating units 5 to be passed is increased, while the water level in the water supply tank 3 is set to each set water level H1. The number of warming units 5 to be passed is decreased every time the value is exceeded.

(C) Every time the water level in the water supply tank 3 falls below each set water level H1 for a set time (first set time), the number of heating units 5 to be passed is increased while the water level in the water tank 3 is increased. Each time the water level continuously exceeds each set water level H1 for a set time (second set time), the number of heating units 5 to be passed is decreased. The first set time and the second set time may be the same or different.

  On the other hand, water supply to the water supply tank 3 via the makeup water channel 10 starts when the water level in the water supply tank 3 falls below the makeup water start water level H2, and exceeds the makeup water stop water level H3 higher than the makeup water start water level H2. And stop. Here, the makeup water start water level H2 is set lower than each set water level H1 (that is, set lower than the lowest set water level H1), and the makeup water stop water level H3 is set higher than each set water level H1 (that is, It is set higher than the uppermost set water level H1).

  Because of such a configuration, for example, the case of (a) will be described as an example. Now, assuming that all of the water supply control electrode rods 24 and the makeup water stop electrode rods 26 detect the water level, the water supply tank 3 As the water level is sufficiently high, the water supply pumps 11 are stopped and the makeup water pump 12 is also stopped. When the water level in the water supply tank 3 drops due to water supply from the water supply tank 3 to the boiler 2 and the uppermost water supply control electrode rod 24 does not detect the water level, the first water supply pump 11 is operated. As a result, water is supplied to the water supply tank 3 through one water supply passage 9, but when the water supply control electrode rod (the uppermost water supply control electrode rod) 24 detects the water level for a set time, the first unit The water supply pump 11 is stopped. On the other hand, even if the first water supply pump 11 is operated, the water level of the water supply tank 3 cannot be recovered, the water level of the water supply tank 3 further decreases, and the water supply control electrode rod 24 second from the top does not detect the water level. Then, when the second water supply pump 11 is operated and the third water supply control electrode rod 24 from the top no longer detects the water level, the third water supply pump 11 is operated so that the water supply pump 11 in the water supply tank 3 is operated. Each time the water level falls below each set water level H1 set in stages, the number of heating units 5 to be passed through is increased. When the lowermost water supply control electrode rod 24 does not detect the water level, the water level cannot be recovered even if all the water supply pumps 11 are operated, and the makeup water start electrode rod 25 does not detect the water level. 12 is also activated. As a result, water is supplied to the water supply tank 3 even through the replenishment water channel 10, but when the water level of the water supply tank 3 recovers and the lowermost water supply control electrode rod 24 detects the water level continuously for a set time, one unit is provided. When the second water supply control electrode rod 24 detects the water level continuously for a set time, the other water pump (here three units) is stopped. The number of heating units 5 to be passed each time the water level in the water supply tank 3 exceeds the set water levels H1 set in stages so as to stop for a set time continuously, such as stopping the water supply pump 11). Will decrease. Thereafter, when the makeup water stop electrode rod 26 detects the water level, the makeup water pump 12 also stops. In addition, about each heating unit 5, the heat source supply pump 22 to the heating unit 5 is also operated while the water supply pump 11 to the heating unit 5 is operating.

  Regarding (b) and (c), whether or not to wait for a set time when each water supply control electrode rod 24 no longer detects the water level when the water level in the water supply tank 3 is lowered, or in the water supply tank 3 When each water supply control electrode rod 24 detects the water level when the water level rises, the control is basically performed in the same manner as in the above (a), except that it waits for a set time.

  In the above example, as the water level of the water supply tank 3 decreases, the water supply pump 11 is started in order of the first, second, third, and so on, and finally when the water level of the water supply tank 3 recovers. The water supply pump 11 is stopped sequentially. For example, when the water level recovers from the operation of the three water supply pumps 11, the third unit, the second unit, and the first unit are sequentially stopped. However, as the water level in the water supply tank 3 recovers, the water supply pump 11 that is started first may be stopped sequentially. For example, when the water level recovers from the operation of the three water supply pumps 11, the first, second, and third units may be sequentially stopped.

  In addition, although related to this, in the series of controls as described above, which water pump 11 is to be preferentially operated among the plurality of water pumps 11 is set in advance and is automatically set by the controller. Selected. However, the water supply pump 11 that operates preferentially may be set manually by the user in the controller. In any case, when the controller detects a failure of any of the heating units 5, it is preferable to continue the control with the heating unit 5 removed.

  In the present embodiment, the makeup water stop water level H3 is set higher than the uppermost set water level H1 among the plurality of set water levels H1. In other words, the lower end portion of the makeup water stop electrode rod 26 is disposed higher than the lower end portion of the uppermost water supply control electrode rod 24. Since the makeup water stop water level H3 is relatively high as compared with the prior art, the water supply speed to the water supply tank 3 can be increased, and a relatively large amount of water can be stored in the water supply tank 3. Therefore, there is no fear that the amount of water stored in the water supply tank 3 will be insufficient, and priority can be given to the operation of the most important boiler 2 and its steam-using equipment. Moreover, the time until the water supply tank 3 is filled with water from an empty state can be shortened.

  The rotation speed of the makeup water pump 12 can be changed by an inverter, and the water supply flow rate to the water supply tank 3 through the makeup water channel 10 is changed as the water level in the water supply tank 3 recovers while the makeup water pump 12 is in operation. You may make it squeeze gradually. For example, the flow rate by the make-up water pump 12 may be reduced stepwise each time the set water level H1 by each water supply control electrode rod 24 is sequentially exceeded. Alternatively, the flow rate of the makeup water pump 12 may be continuously reduced according to the rise in the water level in the water supply tank 3 using a water level detector that can continuously detect the water level in the water supply tank 3.

  As will be described later, the heat pump 4 of each heating unit 5 operates in a predetermined case. The heat pump 4 is switched between operation and stop depending on whether or not the compressor 13 is activated. During the operation of the heat pump 4, the compressor 13 is maintained at a constant power output frequency and a constant output.

  During operation, each feedwater pump 11 is inverter-controlled for rotation speed so as to maintain the temperature detected by the tapping temperature sensor 29 at the target temperature. As will be described later, the target temperature is changed according to the situation.

  As described above, in the feed water heating system 1 according to the present embodiment, the water supply to the water supply tank 3 via each water supply channel 9 is controlled based on the water level in the water supply tank 3. In the heating unit 5 for supplying water to the supplied water tank 3 and passing water therethrough, the heat source fluid temperature to the evaporator 16 is monitored by the heat source temperature sensor 30, and when the temperature exceeds the set temperature, the heat pump 4 is stopped. It is good to let them. Even in that case, as long as the water supply condition based on the water level in the water supply tank 3 is satisfied, the water is supplied to the water supply tank 3 through the water supply path 9.

  More specifically, in the present embodiment, control is performed as follows. That is, in each heating unit 5, if the detected temperature of the heat source temperature sensor 30 is lower than a set temperature (for example, 60 ° C.) during water supply to the water supply tank 3 via the water supply path 9, the heat pump 4 is operated. Thus, the feed water pump 11 is inverter-controlled to maintain the detected temperature of the tapping temperature sensor 29 at the first target temperature (for example, 75 ° C.), and the feed water flow rate to the feed water tank 3 through the feed water passage 9 is adjusted. (First control). Here, the first target temperature is higher than the set temperature.

  During the first control, when the detected temperature of the heat source temperature sensor 30 becomes a set temperature (for example, 60 ° C.) or higher, the control is switched to the second control. In the second control, the heat pump 4 is stopped. Even in this case, as long as the water supply condition based on the water level in the water supply tank 3 is satisfied, water is supplied to the water supply tank 3 through the water supply passage 9, but it is preferable to lower the control target temperature of the outlet side water temperature of the condenser 14. . In other words, the feed water pump 11 is inverter-controlled so that the temperature detected by the hot water temperature sensor 29 is maintained at a second target temperature (for example, 60 ° C.) lower than the first target temperature, and the feed water tank 3 via the feed water passage 9 is controlled. Adjust the water supply flow rate to. Here, the second target temperature is the same temperature as the set temperature, but may be a temperature lower than the set temperature in some cases.

  Thus, if the heat source fluid temperature to the evaporator 16 is lower than the set temperature, the water supply path 9 is maintained so that the outlet side water temperature of the condenser 14 is maintained at the first target temperature while the heat pump 4 is operated. Regardless of the water temperature of the water supply source or the temperature of the heat source fluid, hot water having a desired temperature can be obtained by adjusting the flow rate of the water supply to the water supply tank 3 via the. On the other hand, when the heat source fluid temperature to the evaporator 16 becomes equal to or higher than the set temperature, the heat pump 4 is stopped, so that the compressor 13 can be protected. However, even in that case, the waste heat recovery heat exchanger 18 can exchange heat between the water supply and the heat source fluid to recover the heat from the heat source fluid. Moreover, by switching the control target temperature of the outlet side water temperature of the condenser 14 to the second target temperature that is lower than the first target temperature, the water supply flow rate to the water supply tank 3 through the water supply passage 9 is ensured to some extent. Thus, heat recovery from the heat source fluid can be effectively achieved.

  In each heating unit 5, switching from the second control to the first control is performed as follows. That is, while the heat pump 4 is stopped, the feed water flow rate to the feed water tank 3 through the feed water channel 9 is being adjusted so that the temperature detected by the hot water temperature sensor 29 is maintained at the second target temperature (that is, during the second control). ), When the detected temperature of the heat source temperature sensor 30 continues below the set temperature for a set time (for example, 60 seconds), the process returns to the first control. That is, the heat pump 4 may be restarted and the control may be switched to control for adjusting the feed water flow rate to the feed water tank 3 via the feed water passage 9 so that the temperature detected by the tapping temperature sensor 29 is maintained at the first target temperature.

  However, switching from the second control to the first control may be performed as follows. That is, while the heat pump 4 is stopped, the feed water flow rate to the feed water tank 3 through the feed water channel 9 is being adjusted so that the temperature detected by the hot water temperature sensor 29 is maintained at the second target temperature (that is, during the second control). ) When the temperature detected by the heat source temperature sensor 30 is lower than a predetermined temperature (for example, 58 ° C.) lower than the set temperature, the first control is returned to. That is, the heat pump 4 may be restarted and the control may be switched to control for adjusting the feed water flow rate to the feed water tank 3 via the feed water passage 9 so that the temperature detected by the tapping temperature sensor 29 is maintained at the first target temperature.

  In any case, when the temperature of the heat source fluid to the evaporator 16 is lowered to a predetermined level, the second control in which the heat pump 4 is stopped can be returned to the first control in which the heat pump 4 is operated. In this way, switching between the first control and the second control is performed according to the heat source fluid temperature to the evaporator 16.

  However, in each heating unit 5, when the temperature detected by the heat source temperature sensor 30 in the water supply to the water supply tank 3 through the water supply passage 9 becomes higher than the upper limit temperature (for example, 65 ° C.) higher than the set temperature, The operation of the temperature system 1 should be stopped. Specifically, the heat pump 4 is stopped, the heat source supply pump 22 is stopped, and the supply of the heat source fluid to the evaporator 16 is also stopped. Furthermore, the water supply pump 11 is also preferably stopped. Thus, when the heat source fluid temperature to the evaporator 16 rises excessively, the operation of the feed water heating system 1 can be stopped to protect the feed water warming system 1. Here, the upper limit temperature is higher than the set temperature but lower than the first target temperature.

  In addition, in each heating unit 5, when the water level of the heat source water tank 7 falls during the operation of the heat pump 4 and the low water level detection electrode rod 28 no longer detects the water level, the operation of the heat pump 4 is stopped and the heat source supply pump It is preferable to stop the supply of heat source water to the evaporator 16 by stopping 22. This prevents the heat pump 4 from being wasted. Similarly, each heating unit 5 stops the operation of the heat pump 4 when the amount of water supplied to the water supply tank 3 through the water supply channel 9 is less than the setting value. At the same time, it is preferable to stop the supply of heat source water to the evaporator 16 by stopping the heat source supply pump 22. Further, the water level detector can detect whether the water level in the water supply tank 3 is higher than a predetermined upper limit water level higher than the makeup water stop water level H3 or lower than a predetermined lower limit water level lower than the makeup water start water level H2. When it is detected whether it exceeds the upper limit water level or lower than the lower limit water level, it may be notified that there is an abnormality, or the operation of the feed water heating system 1 may be stopped.

  The feed water warming system 1 of the present invention is not limited to the configuration of the above embodiment, and can be changed as appropriate. In particular, as the water level in the water supply tank 3 decreases, the number of water supply passages 9 in which water supply to the water supply tank 3 is performed (in other words, the number of warming units 5 to be passed through) is increased. If the water level in the water supply tank 3 is increased at the time of recovery, the number of water supply channels 9 in which water supply to the water supply tank 3 is executed (in other words, the number of heating units 5 to be passed through) is reduced. The configuration of can be changed as appropriate.

  For example, in the above-described embodiment, one feed water control electrode rod 24 is used to control the start and stop of each feed water pump 11, but, similar to the control of the makeup water pump 12, for each feed water pump 11, A set of a water supply start electrode rod and a water supply stop electrode rod disposed above the water supply start electrode rod may be used. At this time, the water supply tank 3 may be provided with a water supply stop electrode rod and a water supply start electrode rod so that the lower end portions thereof are alternately lowered, or the lower ends of the respective water supply stop electrode rods having lower lower end portions in order. It may be provided so that the water level area where the section is arranged and the water level area where the lower end part of each water supply starting electrode bar whose lower end part is lowered in order are arranged up and down.

  On the other hand, in the above embodiment, the makeup water start electrode rod 25 and the makeup water stop electrode rod 26 disposed above the same are used to control the start and stop of the makeup water pump 12, but the predetermined water level is set. You may control by either of the following (a)-(c) using the one supplementary water control electrode rod to detect. The predetermined water level is a water level detected by the lower end portion of the makeup water control electrode rod, and is lower than the water level detected by the lower end portion of each water supply control electrode rod 24 (in other words, the highest of the plurality of set water levels H1). It is arrange | positioned below the setting water level H1 below.

(A) Water supply to the water supply tank 3 via the replenishment water channel 10 starts when the water level in the water supply tank 3 falls below a predetermined water level, and stops when the water level continuously exceeds the predetermined water level for a predetermined time.

(B) Water supply to the water supply tank 3 via the replenishment water channel 10 starts when the water level in the water supply tank 3 continues below the predetermined water level for a predetermined time, and stops when the water level exceeds the predetermined water level.

(C) Water supply to the water supply tank 3 through the replenishment water channel 10 starts when the water level in the water supply tank 3 continues below the predetermined water level for a predetermined time (first predetermined time), while the predetermined water level is maintained for a predetermined time. (Second predetermined time) When it exceeds continuously, it stops. The first predetermined time and the second predetermined time may be the same or different.

  Moreover, in the said Example, you may abbreviate | omit installation of one or both among the subcooler 17 and the waste heat recovery heat exchanger 18. FIG. When the installation of the waste heat recovery heat exchanger 18 is omitted, the heating unit 5 can be regarded as the heat pump 4 itself. In that case, since the heat supply water in the waste heat recovery heat exchanger 18 cannot be heated with the heat pump 4 stopped, the start / stop control of the heat pump 4 based on the heat source fluid temperature is not necessary. Therefore, when the water supply pump 11 is operated based on the water level in the water supply tank 3, the heat pump 4 that is caused to flow therethrough is started in conjunction, and when the water supply pump 11 is stopped based on the water level in the water supply tank 3, What is necessary is just to stop the heat pump 4 by which water flow is stopped by interlockingly.

  Moreover, in the said Example, you may abbreviate | omit various control by the tapping temperature sensor 29 and the heat source temperature sensor 30. FIG. Furthermore, in the above-described embodiment, the water supply to the water supply tank 3 through each water supply channel 9 is performed instead of or in addition to controlling the water supply pump 11 installed in each water supply channel 9. The supply of water to the water supply tank 3 via the supply water channel 10 may be performed by installing a supply water pump 12 in the supply water channel 10 and controlling it. Alternatively or in addition, a valve may be installed in the replenishment water channel 10 and controlled.

  Further, in the embodiment, in order to adjust the water supply flow rate to the water supply tank 3 through each water supply path 9, the water supply pump 11 provided in each water supply path 9 is inverter-controlled, but each water supply pump 11 is controlled to be turned on / off. However, the opening degree of the valve provided in each water supply channel 9 may be adjusted. That is, the flow rate adjustment method can be appropriately changed as long as the flow rate of the water supply through each water supply channel 9 can be adjusted based on the temperature detected by the hot water temperature sensor 29 or the like.

  Moreover, in the case of the said Example, as long as the water supply tank 3 can be supplied with water by the some water supply path 9 and can be supplied with the replenishment water path 10, the specific structure of each water supply path 9 and the replenishment water path 10 is the said. Not limited to the configuration of the embodiment, it can be changed as appropriate. For example, in the above-described embodiment, one or both of one end portion (end portion on the supply water tank 6 side) and the other end portion (end portion on the supply water tank 3 side) of each water supply channel 9 and the supply water channel 10 are common. It is good also as a pipe line. In other words, one end of the replenishment water channel 10 is not connected to the replenishment water tank 6, but may be provided so as to branch from a common conduit on the replenishment water tank 6 side of each water supply channel 9. The other end portion of the water supply tank 9 may be connected to the common pipe line on the water supply tank 3 side of each water supply path 9 instead of being connected to the water supply tank 3. When one end of the replenishment water channel 10 is provided not to connect to the replenishment water tank 6 but to branch from the common pipe line on the replenishment water tank 6 side of each water supply channel 9, each water supply is provided downstream from the branch portion. While the water supply pump 11 is provided in the channel 9, the makeup water pump 12 may be provided in the makeup water channel 10. However, a pump is provided only in the common pipe upstream from the branch part, and each water channel downstream from the branch part is provided. 9 and the opening of the valve provided in the supplementary water channel 10 may be adjusted to adjust the flow rate through each of the water supply channels 9 and the supplemental water channel 10.

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

  In the above embodiment, the water supply from the replenishment water tank 6 to the water supply tank 3 can be made via the water supply passages 9 and / or the replenishment water passages 10. However, the water supply may be performed directly from the water softener. For example, in FIG. 1, instead of omitting the installation of the water supply pump 11 by connecting the base ends of the water supply passages 9 and the replenishment water passages 10 together to the water softener, motor valves provided in the water supply passages 9 (motor valves). However, instead of 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 heating unit 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.

  Moreover, although the said Example demonstrated the example using heat source water as a heat source of each heat pump 4, as a heat source fluid of each heat pump 4, not only heat source water but various fluids, such as air and waste gas, can be used. .

  Moreover, in the said Example, when operating each heat pump 4, although the power supply frequency of the motor of the compressor 13 was maintained constant, depending on the case, even if it controls so that the discharge pressure of the compressor 13 may be maintained predetermined. Good. Alternatively, the output of the compressor 13 may be adjusted based on the water level in the water supply tank 3 or the heat source fluid temperature to the evaporator 16.

  Moreover, the heat pump 4 of each heating unit 5 is not limited to a single stage but can be a plurality of stages. When the heat pump 4 has a plurality of stages, adjacent stage heat pumps may be connected using an indirect heat exchanger, or may be connected using a direct heat exchanger (intercooler). In the latter case, an intermediate cooler that receives the refrigerant from the compressor of the low stage heat pump and the refrigerant from the expansion valve of the high stage heat pump and exchanges heat by directly contacting both refrigerants is provided. It is a low-stage heat pump condenser and a high-stage heat pump evaporator. As described above, the multi-stage (multi-stage) heat pump includes a single-stage multi-stage heat pump, a multi-element (multi-element) heat pump, or a combination thereof.

  Moreover, in the said Example, the water pump 11 was started one by one whenever it fell below the step set water level, and the water pump 11 was stopped one by one whenever it exceeded the step set water level. You may control starting or stopping one by one.

  Furthermore, in the said Example, although the compressor 13 of the heat pump 4 was driven by the electric motor in each heating unit 5, the drive source of the compressor 13 is not ask | required in particular. For example, the compressor 13 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.

DESCRIPTION OF SYMBOLS 1 Supply water heating system 2 Boiler 3 Supply water tank 4 Heat pump 5 Heating unit 6 Supply water tank 7 Heat source water tank 8 Pump 9 Supply water path 10 Supply water path 11 Supply water pump 12 Supply water pump 13 Compressor 14 Condenser 15 Expansion valve 16 Evaporation 17 Supercooler 18 Waste heat recovery heat exchanger 19 Heat source supply path 20 Heat source water supply path 21 Overflow path 22 Heat source supply pump 23 Water level detector 24 Water supply control electrode rod 25 Supply water start electrode rod 26 Supply water stop electrode rod 27 Water level detector 28 Low water level detection electrode rod 29 Hot water temperature sensor 30 Heat source temperature sensor H1 Set water level H2 Makeup water start water level H3 Makeup water stop water level

Claims (7)

A water supply tank that is supplied with water through a plurality of water supply channels that are at least partially parallel;
A heat pump that is provided in each of the water supply passages and heats the water supply to the water supply tank;
A water level detector for detecting a plurality of different set water levels in stages in the water supply tank;
And a controller for increasing the number of heat pumps to be passed each time the water level in the water supply tank falls below each of the set water levels based on the detection signal of the water level detector. . The feed water heating system according to claim 1, wherein one of the following (a) to (c) is executed based on a detection signal of the water level detector.
(A) Each time the water level in the water supply tank falls below the set water level, the number of the heat pumps to be passed is increased, while the water level in the water tank continuously exceeds the set water level for a set time. Each time, the number of the heat pumps to be passed is reduced.
(B) Each time the water level in the water supply tank falls below the set water levels for a set time, the number of the heat pumps to be passed is increased, while the water level in the water tank exceeds the set water levels. Each time, the number of the heat pumps to be passed is reduced.
(C) Each time the water level in the water supply tank falls below the set water levels for a set time, the number of the heat pumps to be passed is increased, while the water level in the water tank sets the set water levels. Each time the time is exceeded, the number of the heat pumps to be passed is reduced. The water supply tank can be supplied with water through the heat pump through the water supply channel, and can be supplied through the replenishment water channel without using the heat pump.
Water supply to the water supply tank via the supply water channel starts when the water level in the water supply tank falls below a supply water start water level lower than the lowest set water level of the plurality of set water levels, while replenishment thereof The supply water heating system according to claim 2, wherein the supply water heating system is stopped when a makeup water stop water level higher than a water start water level is exceeded. The supply water heating system according to claim 3, wherein the makeup water stop water level is higher than an uppermost set water level among the plurality of set water levels. The water supply tank can be supplied with water through the heat pump through the water supply channel, and can be supplied through the replenishment water channel without using the heat pump.
The water supply heating system according to claim 2, wherein water supply to the water supply tank via the makeup water channel is controlled by any one of the following (a) to (c).
(A) Water supply to the water supply tank via the makeup water channel starts when the water level in the water supply tank falls below a predetermined water level lower than the lowest set water level of the plurality of set water levels, It stops when it exceeds the predetermined water level for a predetermined time.
(B) When water is supplied to the water supply tank via the makeup water channel, the water level in the water supply tank is continuously lower than a predetermined water level lower than a lowermost set water level among the plurality of set water levels for a predetermined time. On the other hand, it stops when it exceeds the predetermined water level.
(C) When supplying water to the water supply tank via the makeup water channel, the water level in the water supply tank continuously falls below a predetermined water level lower than a lowermost set water level among the plurality of set water levels for a predetermined time. On the other hand, it stops when it exceeds the predetermined water level for a predetermined time. Each water supply path is provided with a heating unit equipped with the heat pump,
Each heating unit is
A supercooler for exchanging heat between the water in the water supply channel upstream of the condenser and the refrigerant from the condenser to the expansion valve;
A waste heat recovery heat exchanger that exchanges heat between the water in the water supply channel upstream of the subcooler and the heat source fluid after passing through the evaporator;
Adjusting the water supply flow rate to the water supply tank via the water supply path so as to maintain the outlet water temperature of the condenser at a target temperature during water supply to the water supply tank via the water supply path. The feed water warming system according to any one of claims 1 to 5. Each of the heating units is configured to stop the heat pump when the heat source fluid temperature to the evaporator becomes equal to or higher than a set temperature during water supply to the water supply tank via the water supply path, and to stop the heat pump. The water supply warming system according to claim 6, wherein water is supplied to the water supply tank.

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