Multi-boiler system

Abstract

To provide a multi-function hot water supply system which can suppress erosion and corrosion of a heat exchange part and can improve hot water supply capacity.SOLUTION: A multi-function hot water supply system (10) includes: a plurality of hot water supply devices (11 to 14) each having a heat exchange part (22) for heating hot water and flow rate adjustment means (34) for adjusting a hot water flow rate of the heat exchange part (22); and a control device (15) for controlling the number of operating units among the plurality of hot water supply devices (11 to 14). The control device (15) has a purpose setting function for setting an operation purpose of the multi-function hot water supply system (10), and sets upper limit flow rates of the heat exchange part (22) for the plurality of hot water supply devices (11 to 14), respectively, according to the set operation purpose.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a multi-boiler system including a plurality of boilers and a control device for controlling the number of operating boilers, which changes the number of operating boilers according to the required amount of heat and heats hot water.

Background Art

[0002] Conventionally, for example, in factories, accommodation facilities, bath facilities, etc., a multi-boiler system that operates a plurality of boilers to heat hot water is used to cope with the case of using a large amount of hot water at once. The multi-boiler system has a control device for controlling the number of operating boilers, and is configured to heat hot water at the number of operating boilers corresponding to the required amount of heat so as to cope with a small amount of hot water supply.

[0003] When a plurality of boilers operate to supply a large amount of hot water at once, the hot water flows at a large flow rate in the heat exchange section that heats the hot water of each boiler. The passage of the hot water in the heat exchange section is often formed of a copper pipe with excellent heat conduction, and since the hot water in which oxygen is dissolved flows, erosion-corrosion is likely to occur particularly when high-temperature hot water flows at a large flow rate. Therefore, for example, as in Patent Document 1, in order to suppress erosion-corrosion, a boiler that restricts the flow rate of hot water in the heat exchanger according to the inlet water temperature of the heat exchanger is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A multi-boiler system may be used, for example, in a factory or the like to store a large amount of hot water heated in a hot water storage tank before use. Also, for example, in a lodging facility, a bath facility, etc., as an immediate hot water supply function in which hot water heated immediately is supplied when a hot water supply faucet is opened, a multi-boiler system may be used as a heat source for an immediate hot water circulation system that circulates while maintaining the temperature of the hot water. On the other hand, in a bath facility, a hot water pool, etc., a multi-boiler system may be used to maintain the temperature of the hot water in a bathtub or pool while filtering the hot water.

[0006] At this time, when the hot water flow rate of the heat exchange part of each hot water supply device is restricted for erosion and corrosion countermeasures as in Patent Document 1, it will operate in a state where the hot water supply capacity is restricted to less than the maximum hot water supply capacity of the hot water supply device. However, depending on the operating purpose of the multi-boiler system, the ease of occurrence of erosion and corrosion is different, so there is room to relax the restriction on the hot water flow rate and improve the hot water supply capacity.

[0007] An object of the present invention is to provide a multi-boiler system capable of suppressing erosion and corrosion of the heat exchange part and improving the hot water supply capacity.

Means for Solving the Problems

[0008] The multi-boiler system according to the invention of claim 1 is a multi-boiler system provided with a plurality of hot water supply devices each having a heat exchange part for heating hot water and a flow rate adjusting means for adjusting the hot water flow rate of the heat exchange part, and a control device for controlling the number of operating units of these plurality of hot water supply devices. The control device has a purpose setting function for setting the operating purpose of the multi-boiler system, and is characterized in that the upper limit flow rate of the heat exchange part is set for each of the plurality of hot water supply devices according to the set operating purpose.

[0009] According to the above configuration, the upper limit flow rates of the heat exchange parts of the plurality of water heaters can be set respectively according to the ease of occurrence of erosion and corrosion that vary depending on the operating purpose of the multi-water heating system. Therefore, in the case of an operating purpose where erosion and corrosion of the heat exchange part are less likely to occur, the upper limit flow rate of the heat exchange part can be set large to suppress erosion and corrosion of the heat exchange part and improve the water supply capacity of the multi-water heating system.

[0010] The multi-water heating system according to the invention of claim 2 is characterized in that, in the invention of claim 1, the setting of the operating purpose is carried out during a trial operation. According to the above configuration, since the operating purpose of the multi-water supply system is set during the trial operation for setting the connection destination of the multi-water supply system, the operating purpose can be set without increasing the work load.

[0011] The multi-water heating system according to the invention of claim 3 is characterized in that, in the invention of claim 1, the operating purpose includes at least water supply, hot water storage circulation, instant hot water circulation, and filtration circulation, and when the filtration circulation is set, the upper limit flow rate is set to a preset maximum flow rate. According to the above configuration, the operating purpose to be set includes at least water supply, hot water storage circulation, instant hot water circulation, and filtration circulation. And when the filtration circulation is set as the operating purpose, the upper limit flow rate of the heat exchange part of each water heater is set to a preset maximum flow rate. In this filtration circulation, since the additional supply of raw water in which oxygen is dissolved is small, erosion and corrosion are less likely to occur compared to other operating purposes. Therefore, in the filtration circulation, the upper limit flow rate in the heat exchange parts of the plurality of water heaters can be set to a maximum flow rate larger than the upper limit flow rate limited in other operating purposes, so as to suppress erosion and corrosion of the heat exchange part and improve the water supply capacity.

Effect of the Invention

[0012] According to the multi-water heating system of the present invention, erosion and corrosion of the heat exchange part can be suppressed and the water supply capacity can be improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

[0014] Hereinafter, embodiments for carrying out the present invention will be described based on examples.

Example

[0015] As shown in FIG. 1, the multi - hot - water supply system 10 is connected so as to heat the city water supplied from the facility - side water - supply pipe 1 to which the city water is supplied as indicated by the arrow W, and supply it to the facility - side hot - water supply pipe 2 equipped with a plurality (here, n) of hot - water taps F1 to Fn. This multi - hot - water supply system 10 has a plurality (for example, four) of hot - water supply devices 11 to 14 and a control device 15 that controls the number of operating units of these hot - water supply devices 11 to 14. The plurality of hot - water supply devices 11 to 14 respectively have, for example, operation remote controls 11a to 14a for performing individual setting operations of the hot - water supply devices 11 to 14. The control device 15 has, for example, an operation remote control 15a for performing setting operations of the multi - hot - water supply system 10.

[0016] A plurality of water heaters 11 to 14 are connected in parallel, and heated hot water can be supplied to a plurality of water faucets F1 to Fn from any of the water heaters 11 to 14. For example, when the water faucet F1 is opened, the hot water heated by one or more selected water heaters (for example, the water heater 11) that are activated by the control device 15 is supplied to the water faucet F1.

[0017] Next, the water heaters 11 to 14 will be described. Since these water heaters 11 to 14 have the same configuration, the water heater 11 will be described, and the description of the water heaters 12 to 14 will be omitted. As shown in FIG. 2, the water heater 11 is a combustion type water heater configured to heat the hot water flowing through the heat exchange unit 22 by using the combustion heat generated when fuel is burned in the combustion unit 21. This water heater 11 has a water supply unit 23 that supplies hot water (city water) to the heat exchange unit 22, and a hot water outlet unit 24 that adjusts the temperature of the hot water heated in the heat exchange unit 22 and discharges the hot water.

[0018] The water supply unit 23 has a water supply passage 25 to which the water supply pipe 1 is connected, a water supply valve 26 that opens and closes the water supply passage 25, a water supply temperature sensor 27 that detects the water supply temperature, and a water supply flow rate sensor 28 that detects the flow rate of the hot water supplied to the heat exchange unit 22.

[0019] The hot water outlet unit 24 has a hot water outlet passage 29 connected to the hot water supply pipe 2, a bypass passage 30 branched from the water supply passage 25 and connected to the hot water outlet passage 29, and a bypass flow rate adjustment valve 31 that adjusts the flow rate of the hot water flowing from the water supply passage 25 into the bypass passage 30. The hot water outlet passage 29 is equipped with a hot water outlet temperature sensor 32 that detects the hot water outlet temperature of the hot water heated in the heat exchange unit 22, a hot water supply temperature sensor 33 that detects the hot water supply temperature of the hot water whose temperature is adjusted by mixing the hot water from the branch passage 30 with the heated hot water, and a hot water outlet flow rate adjustment valve 34. The hot water outlet flow rate adjustment valve 34 is a flow rate adjustment means for adjusting the flow rate of the hot water flowing through the heat exchange unit 22, and together with the bypass flow rate adjustment valve 31, adjusts the hot water outlet flow rate of the temperature-adjusted hot water discharged from the water heater 1.

[0020] The hot water supply device 11 has a control unit 35 that controls the hot water supply operation of the hot water supply device 11. In the hot water supply operation, based on the water supply flow rate, water supply temperature, hot water outlet temperature, and hot water supply temperature, the combustion heat quantity of the combustion unit 21 is adjusted, the opening degree of the flow rate adjustment valve 31 is adjusted, and the hot water adjusted in the hot water outlet unit 24 so that the hot water supply temperature becomes the target temperature is supplied as hot water.

[0021] When the control device 15 is in a standby state where the combustion units 21 of all of the plurality of hot water supply devices 11 to 14 are not burning, for example, when the hot water supply device 11 is selected and the water supply valve 26 of the hot water supply device 11 is opened, the water supply valves 26 of the other hot water supply devices 12 to 14 are closed. In this state, for example, when the hot water tap F1 is opened and the water supply flow rate sensor 28 of the hot water supply device 11 with the water supply valve 26 open detects a flow rate of a predetermined flow rate or more, the hot water supply device 11 operates and a hot water supply operation is performed, and the heated hot water is supplied from the hot water tap F1.

[0022] For example, when a plurality of hot water taps are opened and the hot water supply device 11 alone cannot supply the amount of heat required for hot water supply, the control device 15 opens and operates the water supply valves 26 of the other hot water supply devices 12 to 14 corresponding to the required number of units in order to operate the number of units required to supply the required amount of heat. In this way, the multi-hot water supply system 10 performs operation number control for controlling the number of hot water supply devices operated by the control device 15 according to the required amount of heat, and is configured to cope with hot water supply from a small flow rate to a large flow rate. Note that the control device 15 performs rotation control for periodically changing the order of operation first in order to equalize the operation loads of the plurality of hot water supply devices 11 to 14.

[0023] The multi-hot water supply system 10 is used not only when supplying hot water to a plurality of hot water taps F1 to Fn as shown in FIG. 1, but also as a heat source machine of an instant hot water circulation system 40 in which heated hot water is immediately supplied as soon as the hot water tap is opened as shown in FIG. 3. The instant hot water circulation system 40 has a circulation passage 41 including a plurality of hot water taps F1 to Fn, circulation pumps 42 and 43 interposed in parallel with the circulation passage 41, and a three-way valve 44 for switching the flow path.

[0024] The control device 15 operates either one of the circulation pumps 42 and 43 to constantly circulate hot and cold water through the circulation passage via, for example, the water supply valve 26 of the hot water supply device 11 being open, and periodically switches the three-way valve 44 to alternately drive the circulation pumps 42 and 43 to equalize the driving load. Then, in order to maintain the temperature of the circulated hot and cold water at, for example, the target temperature, the hot water supply device 11 operates to heat the hot and cold water as necessary. For example, when the hot water tap F1 is opened, makeup water corresponding to the amount of hot water supplied from the hot water tap F1 is supplied to the circulation passage 41 as indicated by the arrow W, and the water supply temperature drops, so the hot water supply device 11 is operated to supply hot water. The operation number control and rotation control by the control device 15 are the same as described above.

[0025] Also, the multi-hot water supply system 10 may be used as a heat source machine of the hot water storage circulation system 50 for storing the heated hot and cold water in the hot water storage tank 51 so that a large amount of hot and cold water can be used at once as shown in FIG. 4. In the circulation passage 52 of the hot water storage circulation system 50, the hot water storage tank 51, the circulation pumps 53 and 54, and the three-way valve 55 are interposed, and a tank water supply pipe 56 and a tank hot water outlet pipe 57 are connected to the hot water storage tank 51.

[0026] For example, when a large amount of hot and cold water exceeding the maximum hot water supply capacity of the multi-hot water supply system 10 is used at once, hot and cold water in an amount greater than the usage amount is stored in the hot water storage tank 51 in advance, and the stored hot and cold water is discharged from the tank hot water outlet pipe 57 as indicated by the arrow HW. And simultaneously with the discharge of hot water, makeup water is supplied from the tank water supply pipe 56 to the hot water storage tank 51 as indicated by the arrow W according to the amount of hot water discharged. The multi-hot water supply system 10 heats the low-temperature makeup water in this hot water storage tank 51 and stores it in the hot water storage tank 51. In order to maintain the temperature of the hot and cold water in the hot water storage tank 51, the hot and cold water in the hot water storage tank 51 can also be circulated through the circulation passage 52 and heated by the multi-hot water supply system 10. The operation number control and rotation control by the control device 15 are the same as described above.

[0027] In addition, as shown in FIG. 5, the multi - hot - water supply system 10 may be used as a heat source machine of a filtration circulation system 60 that heats a heat medium for maintaining the temperature of the hot water while filtering the hot water in the bathtub 61 of a bathing facility or the hot water in a hot - water pool, for example, to keep the hot water clean. The filtration circulation system 60 is configured such that a filtration device 67 having a filter 62, a filtration pump 63, a filtration tank 64, a heat exchanger 65, and a chemical unit 66 circulates the hot water through a filtration circulation passage 68, for example, between the filtration device 67 and the bathtub 61.

[0028] The filter 62 collects foreign matters such as hair in the hot water introduced from the bottom of the bathtub 61 into the filtration device 67. The filtration pump 63 circulates the hot water in the bathtub 61 through the filtration circulation passage 68. The filtration tank 64 has a filter medium mainly composed of, for example, porous ceramic particles, and removes impurities that cause turbidity and the like from the hot water passing through the filter medium. The chemical unit 66 injects a chlorine - based chemical (for example, an aqueous solution of sodium hypochlorite, etc.) for sterilizing bacteria derived from the environment or the human body into the hot water returned to the bathtub 61, and maintains a chemical concentration above a certain level to prevent the propagation of bacteria in the bathtub 61.

[0029] The heat exchanger 65 is supplied with the heat medium heated by the multi - hot - water supply system 10 through a heat - medium circulation passage 72 in which circulation pumps 69 and 70 and a three - way valve 71 are installed. One of the circulation pumps 69 and 70 is driven to circulate the heat medium through the heat - medium circulation passage 72, and the hot water in the bathtub 61 introduced into the filtration device 67 is heated by heat exchange with this heat medium to maintain the temperature of the hot water in the bathtub 61. The operation - number control and rotation control by the control device 15 are the same as described above.

[0030] The heat medium is, for example, hot water, and the heat - medium circulation passage 72 is connected to a water source through a makeup valve 73 so that makeup is possible as indicated by an arrow W1. The bathtub 61 is supplied with hot water or makeup water heated by a heat source machine different from the multi - hot - water supply system 10 as indicated by an arrow W2.

[0031] The heat exchange parts 22 of the plurality of water heaters 11 to 14 are formed by bending, for example, a copper pipe excellent in heat conduction as shown in Fig. 2 and attaching a plurality of fins. On the inner wall of this copper pipe, erosion that wears due to flowing hot water occurs. Also, although oxygen is dissolved in the makeup water, when the makeup water is heated, this oxygen easily becomes a gas and comes out, so corrosion (oxidation) of the inner wall of the copper pipe, i.e., corrosion, occurs. The faster the hot water flows, the easier erosion occurs, and the higher the temperature, the easier corrosion occurs. And the location where corrosion occurs is where erosion is most likely to occur. Therefore, when the water heaters 11 to 14 heat and supply hot water at the maximum hot water supply capacity, erosion-corrosion is most likely to occur, the wall thickness of the copper pipe wall becomes thinner, and the deterioration of the heat exchange part 22 progresses rapidly.

[0032] Therefore, the upper limit flow rate of the hot water flowing through the heat exchange part 22 is restricted to a lower flow rate (for example, a flow rate obtained by multiplying the maximum flow rate by a limiting coefficient, such as 25 L / min) than the preset maximum flow rate, suppressing the occurrence of erosion-corrosion. At this time, for example, by adjusting the hot water flow rate adjustment valve 34 and the bypass flow rate adjustment valve 31, the water supply flow rate to the heat exchange part 22 is decreased to be below the upper limit flow rate. Since the upper limit flow rate is restricted, the maximum hot water supply capacity of the plurality of water heaters 11 to 14 may not be exerted.

[0033] On the other hand, when maintaining the temperature of the hot water in the bathtub 61 and the hot water in the warm water pool by filtration circulation as shown in Fig. 5, since the heat medium circulating in the heat medium circulation passage 72 is heated, the amount of dissolved oxygen in the heat medium is limited. Therefore, compared with the hot water supply in Fig. 1, the instant hot water circulation in Fig. 3, and the stored hot water circulation in Fig. 4, where new makeup water is supplied only by the amount of hot water supplied, less oxygen is generated by heating, so erosion-corrosion is less likely to occur.

[0034] Therefore, when the multi-boiler system 10 is used as a heat source unit for maintaining the hot and cold water temperature of the filtration circulation system 60, erosion and corrosion can be suppressed even if the upper limit flow rate of the heat exchange units 22 of the plurality of boilers 11 to 14 is set large. And by setting the upper limit flow rate of the heat exchange unit 22 to the maximum flow rate set in advance, the hot water supply capabilities of the plurality of boilers 11 to 14 can be improved.

[0035] Therefore, the control device 15 is provided with a purpose setting function for setting the operating purpose of the multi-boiler system 10, and the control device 15 sets the upper limit flow rate of the heat exchange units 22 of the plurality of boilers 11 to 14 according to the set operating purpose of the multi-boiler system 10. This setting of the operating purpose can be performed in accordance with the setting of the destination system usually performed during the trial operation of the multi-boiler system 10.

[0036] For example, as shown in FIG. 6, by setting the destination system from the operation remote controller 15a at the start of the trial operation of the multi-boiler system 10, the operating purpose of the corresponding multi-boiler system 10 is automatically set, and the upper limit flow rate of the heat exchange unit 22 corresponding to the operating purpose is automatically set. When the operating purpose is hot water supply, immediate hot water circulation, or stored hot water circulation, the upper limit flow rate is set by multiplying the maximum flow rate set in advance by the limiting coefficients A to C set to positive values less than 1, and when the operating purpose is filtration circulation, it is set to the maximum flow rate set in advance. Note that the limiting coefficients A to C of the set flow rate are set based on experiments or the like, and may be the same value or different values.

[0037] The operation and effects of the multi-boiler system 10 will be described. The control device 15 of the multi - hot - water supply system 10 has a purpose - setting function for setting the operating purpose of the multi - hot - water supply system 10, and sets the upper limit flow rate of the heat exchange section 22 for heating hot water for each of the plurality of hot - water supply devices 11 to 14 according to the set operating purpose. Therefore, according to the ease of occurrence of erosion - corrosion of the heat exchange section 22, which varies depending on the operating purpose of the multi - hot - water supply system 10, the upper limit flow rate of the heat exchange section 22 can be set for each of the plurality of hot - water supply devices 11 to 14. Therefore, in the case of an operating purpose for which erosion - corrosion is less likely to occur, the upper limit flow rate of the heat exchange section 22 can be set large to suppress erosion - corrosion and improve the hot - water supply capacity of the multi - hot - water supply system 10.

[0038] In addition, since the setting of the operating purpose of the multi - hot - water supply system 10 is performed during the trial operation for setting the connection - destination system, the operating purpose can be set without increasing the work load. And the operating purposes to be set include at least hot - water supply, hot - water storage circulation, instant - hot - water circulation, and filtration circulation. When the filtration circulation is set, the upper limit flow rate is set to the preset maximum flow rate. In the filtration circulation, since the additional supply of raw water in which oxygen is dissolved is small, erosion - corrosion of the heat exchange section 22 is less likely to occur compared with other operating purposes. Therefore, in the filtration circulation, the upper limit flow rate in the heat exchange section 22 of the plurality of hot - water supply devices 11 to 14 is set to a maximum flow rate larger than the upper limit flow rate restricted in other operating purposes, so as to suppress erosion - corrosion of the heat exchange section 22 and exert the maximum hot - water supply capacity to improve the hot - water supply capacity.

[0039] In addition, those skilled in the art can implement the above - described embodiments in various modified forms without departing from the spirit of the present invention, and the present invention includes such modified forms.

Explanation of Signs

[0040] 1: Water supply pipe 2: Hot - water supply pipe 10: Multi - hot - water supply system 11 - 14: Hot - water supply devices 15: Control device 21: Combustion section 22: Heat exchange section 23: Water supply section 24: Hot water outlet section 25: Water supply passage 26: Water supply valve 27: Water supply temperature sensor 28: Water supply flow rate sensor 29: Hot water outlet passage 30: Bypass passage 31: Bypass flow rate adjustment valve (flow rate adjustment means) 32: Hot water outlet temperature sensor 33: Hot water supply temperature sensor 34: Hot water outlet flow rate adjustment valve (flow rate adjustment means) 35: Control section 40: Instant hot water circulation system 41: Circulation passage 42, 43: Circulation pump 44: Three-way valve 50: Stored hot water circulation system 51: Stored hot water tank 52: Circulation passage 53, 54: Circulation pump 55: Tank water supply pipe 56: Tank hot water outlet pipe 60: Filtration circulation system 61: Bathtub 62: Filter 63: Filtration pump 64: Filtration tank 65: Heat exchanger 66: Chemical unit 67: Filtration device 68: Filtration circulation passage 69, 70: Circulation pump 71: Three-way valve 72: Heat medium circulation passage 73: Makeup water valve F1~Fn: Hot water faucet

Claims

1. In a multi-boiler system comprising a plurality of water heaters each provided with a heat exchange section for heating hot water and a flow rate adjustment means for adjusting the hot water flow rate of the heat exchange section, and a control device for controlling the number of operating water heaters among these plurality of water heaters, the control device has a purpose setting function for setting the operating purpose of the multi-boiler system, and is characterized in that the upper limit flow rate of the heat exchange section is set for each of the plurality of water heaters according to the set operating purpose.

2. The multi-boiler system according to claim 1, wherein the setting of the operating purpose is performed during a trial operation.

3. The operating purpose includes at least hot water supply, stored hot water circulation, instant hot water circulation, and filtration circulation. The multi-boiler system according to claim 1 is characterized in that when the filtration circulation is set, the upper limit flow rate is set to a preset maximum flow rate.

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