Storage type hot water supply system

Abstract

To provide a technique for suitably executing a freezing preventive operation while improving energy saving performance in a storage type hot water supply system having freezing preventive operation execution means for executing the freezing preventive operation for preventing freezing of retention water in a hot water supply pipeline by heating the hot water supply pipeline.SOLUTION: Freezing preventive operation execution means 52 is configured to enable execution of a hot water use freezing preventive operation A1 for causing hot water HW stored in a hot water storage tank 5 to flow in a hot water supply pipeline 6 and an electric power use freezing preventive operation A2 for heating the hot water supply pipeline 6 by using an electric heater 9, as a freezing preventive operation. When executing the freezing preventive operation, the freezing preventive operation execution means 52 executes execution target determination processing for alternatively determining the freezing preventive operation to be executed from the hot water use freezing preventive operation A1 and the electric power use freezing preventive operation A2 on the basis of a state of energy consumption.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hot water storage type hot water supply system comprising a heat source unit that generates hot water, a hot water storage tank that can temporarily store the hot water, a hot water supply pipe that directs the hot water to a hot water supply destination, and a freeze prevention operation execution means that heats the hot water supply pipe to perform a freeze prevention operation to prevent stagnant water in the hot water supply pipe from freezing. [Background technology]

[0002] Conventional hot water storage type hot water supply systems include those that perform a hot water-based anti-freeze operation in which hot water stored in a hot water storage tank is circulated through the hot water supply pipe as a freeze prevention operation (see, for example, Patent Document 1), and those that perform an electricity-based anti-freeze operation in which the hot water supply pipe is heated by an electric heater (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-159531 [Patent Document 2] Japanese Patent Publication No. 2023-014730 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional hot water storage and supply systems, only one of the following freeze prevention operations is performed: hot water-based freeze prevention operation or electricity-based freeze prevention operation. Therefore, the actual execution cost required to perform the freeze prevention operation is determined by the circumstances. However, there is a demand for reducing the execution cost of the freeze prevention operation in order to improve energy conservation.

[0005] In addition, in a hot water storage type hot water supply system that performs hot water utilization freeze prevention operation as a freeze prevention operation, problems may arise in performing hot water utilization freeze prevention operation depending on the state of heat demand as energy consumption, such as when there is a high heat demand and a shortage of hot water stored in the hot water storage tank, making it impossible to perform hot water utilization freeze prevention operation normally, or when energy saving performance is reduced by operating the heat source unit solely for performing hot water utilization freeze prevention operation.

[0006] On the other hand, in a storage-type hot water supply system that performs electricity-utilizing freeze prevention operation as a freeze prevention operation, if electricity demand is high and power supply is tight, problems may arise in performing electricity-utilizing freeze prevention operation depending on the state of electricity demand as energy consumption, such as when electricity-utilizing freeze prevention operation cannot be performed normally or when expensive electricity needs to be received in order to perform electricity-utilizing freeze prevention operation.

[0007] In view of this situation, the main objective of the present invention is to provide a technology for optimally executing anti-freeze operation while improving energy efficiency in a storage-type hot water supply system equipped with a means for executing anti-freeze operation that heats the hot water supply pipe to prevent stagnant water in the hot water supply pipe from freezing. [Means for solving the problem]

[0008] A first characteristic configuration of the present invention is a water heater including a heat source unit that generates hot water, a hot water storage tank that can temporarily store the hot water, and a hot water supply pipe that guides the hot water to a hot water supply destination, A hot water storage type hot water supply system including: a freeze prevention operation execution means for executing a freeze prevention operation that heats the hot water supply pipe to prevent freezing of stagnant water in the hot water supply pipe, the freeze prevention operation execution means is configured to be able to execute, as the freeze prevention operation, a hot water-using freeze prevention operation in which hot water stored in the hot water storage tank is caused to flow through the hot water supply pipe line, and an electricity-using freeze prevention operation in which the hot water supply pipe line is heated by an electric heater, The anti-freeze operation execution means executes an execution target determination process to selectively determine the anti-freeze operation to be executed from the hot water-using anti-freeze operation and the electricity-using anti-freeze operation based on the state of energy consumption when the anti-freeze operation is executed.

[0009] According to this configuration, the freeze prevention operation execution means can selectively execute either the hot water-based freeze prevention operation or the electric power-based freeze prevention operation. The freeze prevention operation execution means then executes the execution target determination process based on the energy consumption status of heat demand and electric power demand when executing the freeze prevention operation due to, for example, a drop in outside air temperature. This allows the freeze prevention operation execution means to determine and execute the freeze prevention operation that, between the hot water-based freeze prevention operation and the electric power-based freeze prevention operation, causes fewer problems while reducing execution costs. Therefore, the present invention provides a technology for optimally executing anti-freeze operation while improving energy efficiency in a hot water storage type hot water supply system equipped with a means for executing anti-freeze operation that heats the hot water supply pipe to prevent stagnant water in the hot water supply pipe from freezing.

[0010] A second characteristic configuration of the present invention is that, in the execution target determination process, the freeze prevention operation execution means calculates the execution costs of the hot water-using freeze prevention operation and the electricity-using freeze prevention operation as the state of the energy consumption, and determines the hot water-using freeze prevention operation or the electricity-using freeze prevention operation with the lower execution cost as the operation to be executed.

[0011] According to this configuration, in the process of determining the operation to be performed, the operation to be performed is determined to be the operation to be performed, whichever operation has the lower pre-calculated execution cost between hot water-based anti-freeze operation and electricity-based anti-freeze operation, thereby ensuring a reduction in the actual execution cost required to operate the anti-freeze operation.

[0012] The third characteristic configuration of the present invention is that when the anti-freeze operation execution means is in a power-stressed state in which the power demand as the energy consumption state exceeds a predetermined set power demand, it determines that the hot water-using anti-freeze operation is to be executed regardless of the result of the execution target determination process.

[0013] According to this configuration, even if the electric power-using freeze prevention operation is initially selected as the operation to be performed in the execution target determination process, if the power supply is in a tight power state, the hot water-using freeze prevention operation is selected as the operation to be performed. This reliably avoids receiving expensive electric power in the power-constrained state to activate the electric power-using freeze prevention operation, thereby further improving energy savings and avoiding problems that may arise from the execution of the electric power-using freeze prevention operation in the power-constrained state.

[0014] A fourth characteristic configuration of the present invention is that when the energy consumption state is a state of hot water shortage in which the amount of hot water stored in the hot water storage tank is less than a predetermined set amount of hot water, the freeze prevention operation execution means determines the electricity-using freeze prevention operation to be the operation target regardless of the result of the execution target determination process.

[0015] According to this configuration, even if the hot water-using freeze prevention operation is initially selected as the operation to be performed in the execution target determination process, if the hot water shortage state occurs, the electricity-using freeze prevention operation is selected as the operation to be performed. This reliably avoids operating the heat source unit solely to perform the hot water-using freeze prevention operation in the hot water shortage state, thereby further improving energy savings and avoiding problems that may arise from performing the hot water-using freeze prevention operation in the hot water shortage state. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing the configuration of a hot water storage type hot water supply system according to an embodiment of the present invention. [Figure 2] A diagram showing the flow of determining targets for anti-freeze operation and their execution. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hot water storage type hot water supply system according to the present invention will be described with reference to the drawings. As shown in Fig. 1, the hot water storage type hot water supply system of this embodiment (hereinafter referred to as the present system) is provided with a cogeneration system 1 that uses fuel gas G as a heat source for generating hot water HW, interconnected to electricity E received from a commercial power system 20 to generate electricity, and generates hot water HW from the heat generated by the electricity generation. The present system also includes a sealed hot water storage tank 5 for temporarily storing the hot water HW, a hot water supply pipeline 6 for directing the hot water HW to various hot water supply destinations such as a hot water tap 12 and a bathtub 14, and a control device 50 for controlling the operation of the present system.

[0018] That is, in the heating circuit 2 that circulates hot water between the cogeneration system 1 and the hot water tank 5, the feed water CW at the bottom of the hot water tank 5 is heated by the cogeneration system 1 to generate hot water HW, and this hot water HW is introduced into the top side of the hot water tank 5, so that the hot water HW is stored in a state where temperature stratification is formed in the hot water tank 5. Then, when the user opens the hot water tap 12 or when the user operates the bathtub fill button and opens the bathtub filling valve 15, the hot water HW taken out from the top of the hot water tank 5 is supplied to the hot water tap 12 or the bathtub 14 through the hot water supply pipe 6.

[0019] The hot water supply pipe 6 is provided with a mixing valve 8 that can mix low-temperature feed water CW from a water supply pipe 18 with the hot water flowing through the hot water supply pipe 6. Furthermore, the hot water supply pipe 6 is provided with an auxiliary heat source device 10 that can heat the hot water flowing through the hot water supply pipe 6 using fuel gas G. In other words, when supplying hot water to the hot water tap 12 or the bathtub 14, if the temperature of the hot water flowing through the hot water supply pipe 6 is below the desired set temperature, the auxiliary heat source device 10 is activated, the hot water is heated, and becomes hot water HW of the desired temperature, which is then supplied to the hot water tap 12 or the bathtub 14. Further, the hot water supply pipe 6 is provided with an electric heater 9 for preventing the water stagnating in the hot water supply pipe 6 from freezing, the details of which will be described later.

[0020] Furthermore, the electric heater 9 and other power loads 21 are supplied with electric power E received from the commercial power grid 20 or electric power E generated by the cogeneration system 1. The operating state of the cogeneration system 1 can be appropriately controlled by the control device 50. For example, by operating the cogeneration system 1 only when the power generation cost calculated from the price of fuel gas G consumed by the cogeneration system 1 is lower than the power reception cost when receiving electric power E from the commercial power grid 20, it is possible to supply the electric heater 9 and other power loads 21 with the electric power E generated by the cogeneration system 1 or the electric power E received from the commercial power grid, whichever has the lower energy cost.

[0021] The control device 50 is configured as a computer system, and functions as a freeze prevention necessity determination means 51 and a freeze prevention operation execution means 52, which will be described later, by executing a predetermined computer program. The freeze prevention necessity determination means 51 is configured as a means for determining whether or not there is a risk of stagnant water in the hot water supply pipe 6 freezing. For example, the freeze prevention necessity determination means 51 accesses an external weather information providing system via a communication network such as the Internet line, and checks, from weather data obtained from the weather information providing system, whether a low temperature warning has been issued or whether the outside temperature is below freezing. Then, for time periods when a low temperature warning has been issued or the outside temperature is below freezing, it determines that there is a risk of stagnant water in the hot water supply pipe 6 freezing, and that prevention of freezing is necessary. On the other hand, the anti-freeze operation execution means 52 is configured as a means for executing an anti-freeze operation that heats the hot water supply pipe 6 to prevent the accumulated water in the hot water supply pipe 6 from freezing. This system is a storage-type hot water supply system equipped with such a freeze prevention operation execution means 52, and adopts a configuration that allows for the optimal execution of freeze prevention operation while improving energy saving, the details of which are explained below.

[0022] The freeze prevention operation execution means 52 is configured to be able to selectively execute either the hot water-using freeze prevention operation A1 or the electricity-using freeze prevention operation A2 as the freeze prevention operation. Hot water utilization anti-freeze operation A1 is an anti-freeze operation in which hot water HW stored in hot water storage tank 5 is passed through hot water supply pipe 6. Specifically, in hot water utilization anti-freeze operation A1, bathtub filling valve 15 is opened, and hot water HW stored in hot water storage tank 5 is drained into bathtub 14 through hot water supply pipe 6. At this time, the flow rate of hot water HW is adjusted to a small amount by a flow control valve (not shown). This heats the entire hot water supply pipe 6 to a temperature that prevents the freezing of stagnant water. Furthermore, when draining water into the bathtub 14 in conjunction with the execution of the hot water use anti-freeze operation A1, it is desirable to notify the user in advance and urge them to be careful so that they do not mistakenly believe that there is a malfunction or abnormality.

[0023] On the other hand, the electricity-using freeze prevention operation A2 is a freeze prevention operation in which the hot water supply pipe 6 is heated by the electric heater 9. Specifically, in the electricity-using freeze prevention operation A2, the electric heater 9 is started to operate, and the hot water supply pipe 6 is heated to a temperature that will prevent the freezing of the stagnant water. At this time, with the bathtub filling valve 15 open, a small amount of feedwater CW may be passed through the mixing valve 8 into the hot water supply pipe 6. In this way, the feedwater CW heated by the electric heater 9 is supplied to the bathtub 14 through the hot water supply pipe 6. In this way, the entire hot water supply pipe 6 is heated to a temperature that will prevent the freezing of the stagnant water. Furthermore, when draining water into the bathtub 14 in conjunction with the execution of the power-using anti-freeze operation A2, it is desirable to notify the user in advance and urge them to be careful so that they do not mistakenly believe that there is a malfunction or abnormality.

[0024] Furthermore, the freeze prevention operation execution means 52 is configured to execute an execution target determination process that, when the freeze prevention operation is being executed, selectively determines which of the hot water-using freeze prevention operation A1 and the electric power-using freeze prevention operation A2 is to be executed based on the state of energy consumption for heat demand and electric power demand in the facility where the system is installed. As a result, of the hot water-using freeze prevention operation A1 and the electric power-using freeze prevention operation A2, the freeze prevention operation that reduces execution costs and causes fewer problems when activated is selected and activated. A specific flow of the determination and execution of the antifreeze operation by the antifreeze operation execution means 52 will be described below with reference to FIG.

[0025] First, when the freeze prevention necessity determining means 51 determines that freeze prevention is necessary (Yes in step #1), an execution target determination process is executed. In this execution target determination process, an execution cost C1 required to execute the hot water-using freeze prevention operation A1 and an execution cost C2 required to execute the electricity-using freeze prevention operation A2 are calculated (step #2). The execution cost C1 of the hot water-using freeze prevention operation A1 is calculated as the operating cost of the cogeneration system 1 required to obtain the hot water HW consumed in the hot water-using freeze prevention operation A1. On the other hand, the execution cost C2 of the power-utilizing freeze prevention operation A2 is the cost required to obtain the electricity E consumed in the power-utilizing freeze prevention operation A2, and is calculated from the electricity receiving cost if the electricity E is received from the commercial power grid 20, and is calculated from the electricity generation cost if the electricity E is generated by the cogeneration system 1.

[0026] In the execution target determination process, except for exceptions due to the determination processes of steps #4 and #6 described below, if the execution cost C1 of hot water-using freeze prevention operation A1 is less than the execution cost C2 of electricity-using freeze prevention operation A2 (Yes in step #3), hot water-using freeze prevention operation A1 is determined to be the operation to be executed (step #5). Conversely, if the execution cost C1 of hot water-using freeze prevention operation A1 is equal to or greater than the execution cost C2 of electricity-using freeze prevention operation A2 (No in step #3), electricity-using freeze prevention operation A2 is determined to be the operation to be executed (step #7). In this manner, the operation with the lower execution cost C1, C2, between hot water-using freeze prevention operation A1 and electricity-using freeze prevention operation A2 is determined to be the operation to be executed. Then, the freeze prevention operation determined to be the operation to be executed is executed (step #8). This reliably reduces the actual execution cost required to activate the freeze prevention operation.

[0027] Even if the execution cost C1 of hot water-using freeze prevention operation A1 is less than the execution cost C2 of electricity-using freeze prevention operation A2 (Yes in step #3), if the state of energy consumption is a hot water shortage state in which the amount of hot water stored in hot water storage tank 5 is less than the predetermined set hot water storage amount (Yes in step #4), hot water-using freeze prevention operation A1 is determined to be the operation to be executed (step #7) regardless of the determination result of the execution target determination process described above. This reliably avoids operating the cogeneration system 1 to generate hot water HW just to execute hot water-using freeze prevention operation A1 in a hot water shortage state, thereby further improving energy conservation. Furthermore, the above-mentioned amount of stored hot water can be detected by distributing multiple temperature sensors (not shown) in the vertical direction of the hot water storage tank 5, which stores hot water HW in a state where temperature stratification is formed, to measure the temperature of the hot water stored in the hot water storage tank 5, and by measuring the measurement results of these multiple temperature sensors.

[0028] Even if the execution cost C1 of hot water-using freeze prevention operation A1 is equal to or greater than the execution cost C2 of electricity-using freeze prevention operation A2 (No in step #3), if the power demand as the energy consumption state exceeds a predetermined set power demand, resulting in a power tightness state (Yes in step #6), hot water-using freeze prevention operation A1 is determined to be the operation to be executed (step #5) regardless of the result of the execution target determination process described above. This reliably avoids receiving expensive electricity E from the commercial power grid 20 to activate electricity-using freeze prevention operation A2 in a power tightness state, thereby further improving energy conservation. The power demand can be measured as the amount of power consumed by the power load 21 in the facility where the system is installed, but it may also be the amount of power demand in the entire area supplied by the commercial power grid 20. In this case, the power company that operates the commercial power grid 20 determines whether or not the power demand exceeds the set power demand, resulting in a power shortage, and the control device 50 on the system side can receive the determination result from the power company side via a communication network such as the Internet line.

[0029] [Another embodiment] Other embodiments of the present invention will be described below. Note that the configurations of the embodiments described below are not limited to being applied independently, but can also be applied in combination with the configurations of other embodiments.

[0030] (1) In the above embodiment, in the process for determining the operation to be performed, the anti-freeze operation to be performed was determined alternatively from hot water-using anti-freeze operation A1 and electricity-using anti-freeze operation A2 based on the respective execution costs C1, C2 of the hot water-using anti-freeze operation A1 and electricity-using anti-freeze operation A2 as the state of energy consumption. However, the anti-freeze operation may also be determined based on factors other than the execution costs C1, C2, such as the heat consumption (amount of hot water supplied) of each hot water supply from the hot water tap 12, bathtub 14, etc., or the amount of power consumed by each power load 21.

[0031] (2) In the above embodiment, as an exception to the determination of the execution target by the execution target determination process, a process was executed in which, when there is a hot water shortage (Yes in step #4), the hot water-using anti-freeze operation A1 is determined to be the execution target (step #7) regardless of the result of the execution target determination process, and a process was executed in which, when there is a power shortage (Yes in step #6), the hot water-using anti-freeze operation A1 is determined to be the execution target (step #5) regardless of the result of the execution target determination process.However, one or both of these exception processes may be omitted as appropriate. [Explanation of symbols]

[0032] 1 Combined heat and power supply device (heat source) 5. Hot water tank 6 Hot water supply pipes 9 Electric heater 12 Hot water tap (hot water supply destination) 14 Bathtub (hot water supply destination) 52 Anti-freeze operation implementation measures A1 Hot water use anti-freeze operation A2 Electric power use anti-freeze operation C1 Execution Cost C2 Execution Cost E-power HW hot water

Claims

1. The hot water supply system includes a heat source unit that generates hot water, a hot water storage tank that can temporarily store the hot water, and a hot water supply pipe that guides the hot water to a hot water supply destination. A hot water storage type hot water supply system including: a freeze prevention operation execution means for executing a freeze prevention operation that heats the hot water supply pipe to prevent freezing of stagnant water in the hot water supply pipe, the freeze prevention operation execution means is configured to be able to execute, as the freeze prevention operation, a hot water-using freeze prevention operation in which hot water stored in the hot water storage tank is caused to flow through the hot water supply pipe line, and an electricity-using freeze prevention operation in which the hot water supply pipe line is heated by an electric heater, A hot water storage type hot water supply system in which the freeze prevention operation execution means executes an execution target determination process to selectively determine the freeze prevention operation to be executed from the hot water use freeze prevention operation and the electricity use freeze prevention operation based on the state of energy consumption when the freeze prevention operation is executed.

2. A hot water storage type hot water supply system as described in claim 1, wherein the freeze prevention operation execution means, in the execution target determination process, calculates the execution costs of each of the hot water-using freeze prevention operation and the electricity-using freeze prevention operation as the state of the energy consumption, and determines the hot water-using freeze prevention operation or the electricity-using freeze prevention operation with the lower execution cost as the operation to be executed.

3. A hot water storage type hot water supply system as described in claim 1 or 2, wherein the freeze prevention operation execution means determines the hot water use freeze prevention operation to be executed when the power demand as the energy consumption state exceeds a predetermined set power demand amount, regardless of the result of the execution target determination process.

4. A hot water storage type hot water supply system as described in claim 1 or 2, wherein the freeze prevention operation execution means determines the electricity-using freeze prevention operation to be executed when the hot water storage amount in the hot water storage tank as the energy consumption state is less than a predetermined set hot water storage amount, regardless of the result of the execution target determination process.

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