JP2003148805A - Cogeneration system and unit therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of sensors necessary for feed-forward controlling a mixture ratio of primary hot water and cold water in a cogeneration system for mixing the primary hot water heated by power generation exhaust heat with the cold water, and heating the same by a water heater to adjust the hot water to a set temperature. SOLUTION: A unit 88 is connected between the hot water storing tank 49 for the primary hot water heated by power generation exhaust heat and the water heater 81 for supplying the secondary hot water of set temperature. The unit 88 comprises a mixing unit 75 for receiving and mixing the primary hot water and the cold water, and supplying the same to the water heater, mixture ratio adjusting units 63, 65 for adjusting a mixture ratio of the primary hot water and the cold water to be mixed, a first temperature sensor 71 for measuring a temperature of the primary hot water before mixing, a flow rate sensor 78 for measuring a flow rate of the hot water after mixing, and a means for determining the mixture ratio. The mixture ratio determining means 86 determines the mixture ratio to obtain the calculated supply temperature after mixing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cogeneration system that includes a power generation system and a hot water supply system and can increase total energy efficiency by using exhaust heat generated by power generation to obtain hot water. In particular, the present invention relates to an improved cogeneration system capable of stably supplying hot water adjusted to a temperature set by a person who needs hot water (hereinafter referred to as a set temperature). It also relates to a unit suitable for constructing the cogeneration system.

[0002]

2. Description of the Related Art The above-mentioned cogeneration system has been put into practical use. The cogeneration system described in Japanese Patent Laid-Open No. 2001-65975, which seems to be most relevant to the present invention, will be described with reference to FIG. As shown in FIG. 1, this cogeneration system uses a fuel cell to generate electricity.
And a hot water supply system 1. The hot water supply system 1 uses a waste heat generated from the power generation system 2 to heat hot water, a hot water storage tank 14 for storing the primary hot water heated by the waste heat generated by the heat exchanger 8, and a hot water storage tank. A hot water supply system 18 is provided for adjusting the temperature of the primary hot water stored in 14 to a set temperature and supplying hot water to the hot water required portion 36.
The temperature-controlled hot water supply system 18 includes a means 28 for mixing the primary hot water and the cold water, and a heating means 34 for heating the mixed hot water. Generally, if the temperature of the primary hot water is higher than the set temperature, the secondary hot water mixed with cold water and mixed is supplied to the hot water required portion 36, and if the temperature of the primary hot water is lower than the set temperature, it is heated by the heating means 34. The heated secondary hot water is supplied to the hot water required portion 36.

The fuel cell type power generation system 2 is composed of a reformer and a fuel cell (not shown). The reformer produces hydrogen gas from a hydrocarbon-based raw fuel. Fuel cells generate electric power by reacting hydrogen gas with oxygen gas in the air. Exhaust heat is generated in the fuel cell power generation system 2 along with power generation. The generated heat is recovered by the heat medium circulating in the power generation system 2. The heat medium circulation passage in the power generation system 2 extends to the outside and passes through the heat exchanger 8. A heat medium pump 6 is arranged in the heat medium circulation passage 4. The heat medium for recovering the generated exhaust heat is circulated through the heat medium circulation passage 4 by the heat medium pump 6.

Primary hot water is stored in the hot water storage tank 14. A cold water supply pipe 16 is connected to the hot water storage tank 14. The cold water supply pipe 16 guides the cold water into the hot water storage tank 14 when the capacity of the primary hot water in the hot water storage tank 14 becomes a predetermined value or less. The hot water circulation passage 12 is connected to the hot water storage tank 14. Hot water circulation passage 1
2 passes through the heat exchanger 8. A hot water pump 10 is provided in the hot water circulation passage 12. The primary hot water stored in the hot water storage tank 14 circulates in the hot water circulation passage 12 by the hot water pump 10.

The heat medium circulation passage 4 and the hot water circulation passage 12 pass through the heat exchanger 8, the heat medium is cooled by the primary hot water, and the primary hot water is heated by the heat medium. Heated by the exhaust heat of power generation
The hot water stored in is called primary hot water. The temperature of the primary hot water changes depending on the amount of power generation, and does not correspond to the hot water set temperature set by a person who needs hot water. The primary hot water may be higher or lower than the set temperature.

A primary hot water supply pipe 20 is connected to the upper part of the hot water storage tank 14. The primary hot water supply pipe 20 is connected to the mixing means 28. The cold water supply pipe 26 is connected to the mixing means 28. The mixing means 28 mixes the primary hot water from the primary hot water supply pipe 20 and the cold water from the cold water supply pipe 26.
The mixing means 28 can individually adjust the flow rates of the primary warm water and the cold water to be mixed. The mixing means 28 is connected to the heating means 34 via a mixing hot water pipe 32. The heating means 34 has a built-in heating means such as a gas burner. If the temperature of the primary hot water in the hot water storage tank 14 is higher than the set temperature, it is mixed with cold water, and the hot water mixed and adjusted to the set temperature is supplied to the hot water required portion 36. If the temperature of the primary hot water is lower than the set temperature, it is heated by the heating means 34, and the hot water heated and adjusted to the set temperature is supplied to the hot water required portion 36. Hot water whose temperature is controlled to the set temperature is called secondary hot water.

Various sensors are used in the above cogeneration system in order to adjust the temperature of the secondary hot water to a set temperature. The primary hot water supply pipe 20 is provided with a first temperature sensor 22a that measures the temperature of the primary hot water before mixing and a first flow rate sensor 22b that measures the flow rate. The first temperature sensor 22a and the first flow sensor 22b are collectively referred to as the first measuring means 22. The cold water supply pipe 26 mixed with the primary hot water is provided with a second temperature sensor 24a for measuring the temperature of the cold water and a second flow rate sensor 24b for measuring the flow rate. Second
The temperature sensor 24a and the second flow rate sensor 24b are combined into a second
It is called measuring means 24. The mixed hot water pipe 32 is provided with a third temperature sensor 30a that measures the temperature of the hot water after mixing and a third flow rate sensor 30b that measures the flow rate. The third temperature sensor 30a and the third flow rate sensor 30b are collectively referred to as third measuring means 30.

In the above cogeneration system,
The flow rates of the primary hot water and the cold water mixed by the mixing means 28 are determined from the measurement result of the third measuring means 30. The temperature obtained by subtracting the temperature rise by the heating means 34 from the set temperature adjusted by the heating means 34 is compared with the measured value of the third temperature sensor 30a. If the latter is lower than the former, the flow rate of the primary hot water is increased. Or reduce the flow rate of cold water. If the latter is higher than the former, the flow rate of primary hot water is decreased or the flow rate of cold water is increased. Since the temperature rise by the heating means 34 changes depending on the flow rate passing through the heating means 34, the former temperature is calculated from the measurement value of the third flow rate sensor 30b.

In the above feedback control method, the hot water supply temperature immediately after the start of hot water supply cannot be adjusted to the set temperature. In the feedback method, it takes time to match the temperature of the hot water supplied to the hot water supply point 36 with the set temperature. Therefore, in the technique described in the above publication, the first measuring means 2
From the measurement results of the temperature and flow rate of the primary hot water measured in 2 and the temperature and flow rate of the cold water measured in the second measuring means 24, the hot water temperature after mixing is heated from the set temperature adjusted by the heating means 34. Feed-forward control is performed by calculating a hot water flow rate and a cold water flow rate that match the temperature obtained by subtracting the temperature rise by the means 34. Temperature T measured by the first temperature sensor 22a
When the flow rate of the primary hot water of H is VH and the flow rate of the cold water of the temperature TL measured by the second temperature sensor 24a is VL, the hot water temperature after mixing is (TH · VH + TL · VL) / (VH
+ VL), and the flow rate should be VH + VL. In the above-mentioned conventional technique, VH + VL is equal to the measurement value of the second flow rate sensor 30b, and (TH · VH + TL · V
Assuming that (L) / (VH + VL) is equal to the temperature at which the temperature is heated to the set temperature by the heating means 34, VH and VL are solved. In this case, since the temperature rise by the heating means 34 changes depending on the flow rate passing through the heating means 34, the temperature of the mixed hot water to be input to the heating means 34, that is, (TH · VH + TL · VL) / (VH +
The value of (VL) is calculated from the set temperature and the measurement value of the second flow sensor 30b. If the measured value of the first flow rate sensor 22b is equal to the solved VH and the measured value of the second flow rate sensor 24b is equal to the solved VL, the intended feedforward control is realized. By performing the feedforward control, the secondary hot water adjusted to the set temperature can be supplied immediately after the hot water supply is started.

[0010]

In the technique described in the above publication, the number of sensors required for feedforward control is large, and the arithmetic expression for feedforward control becomes complicated. That is, a total of three temperature sensors 22a, 30
a, 24a and a total of three flow rate sensors 22b, 30b,
24b is required. Note that the publication describes that one of the three flow rate sensors 22b, 30b, and 24b can be omitted. However, even if omitted, three temperature sensors and two flow rate sensors are required. In addition, in the above method, the amount of the secondary hot water discharged from the heating means 34 is not stable, which may give the user discomfort. The present invention was created in view of the above-mentioned circumstances, and an object of the present invention is to realize a technique that enables feedforward control of the mixing ratio of primary hot water and cold water with a smaller number of sensors than conventional sensors.

[0011]

[Means for Solving the Problems, Actions and Effects] According to the study by the present inventors, when a water heater is used as the heating means, it is necessary to individually measure the flow rate of the primary hot water before mixing and the flow rate of cold water mixed with it. Therefore, it was found that feedforward control can be performed using only the flow rate of the mixed hot water supplied to the water heater.

The invention according to claim 1 is a unit used by being connected between a hot-water storage tank for primary hot water heated by exhaust heat from power generation and a water heater for discharging secondary hot water adjusted to a set temperature. Regarding A cogeneration system is constructed by connecting these units. This unit receives the primary hot water and the cold water, mixes them and supplies them to the water heater, the mixing ratio controller that adjusts the mixing ratio of the primary hot water and the cold water to be mixed, and the temperature of the primary hot water before mixing. A first temperature sensor, a flow rate sensor for measuring the hot water flow rate after mixing, and a means for determining the mixing ratio. The mixing ratio determination means calculates a supply temperature to be supplied to the water heater by subtracting the minimum heating temperature obtained by dividing the minimum heating amount of heat of the water heater by the measurement value of the flow rate sensor from the set temperature, From the measured value of the temperature sensor, the mixing ratio at which the hot water temperature after mixing becomes the calculated supply temperature is determined. As described later, this unit preferably further includes a third temperature sensor that measures the temperature of the hot water after mixing and a second temperature sensor that measures the temperature of the cold water to be mixed. On the other hand, a sensor for measuring the flow rate of primary hot water to be mixed and a sensor for measuring the flow rate of cold water are not required. The mixing ratio here is the primary hot water flow rate / (primary hot water flow rate + cold water flow rate) or cold water flow rate /
(Primary hot water flow rate + cold water flow rate), which is 1.00 (100%) when both are added, so that one can be calculated from the other. When the water heater is of a type that burns and heats the fuel, there is a minimum amount of heat for stable combustion, and there is a minimum amount of heat that causes poor combustion if the heat is adjusted to a lower level. The above-mentioned minimum heating heat quantity refers to this heat quantity.

When the method of controlling the primary hot water flow rate and the cold water flow rate individually is changed to the method of adjusting the mixing ratio, it is not necessary to measure the primary hot water flow rate and the cold water flow rate individually, and only the water quantity after mixing is measured. The intended feedforward control can be performed only by itself. That is, when the hot water output temperature of the water heater is TS (set temperature), the amount of water after mixing is VM, and the minimum heating amount QM of the water heater is QM, divide QM by VM to convert it to a unit of temperature. Is the minimum temperature rise ΔT due to the water heater
M is calculated. The temperature of the primary hot water before mixing, which is measured by the first temperature sensor, is TH, and the temperature of the cold water is TL (this is preferably measured as described below, but the cold water is compared with the temperature change width of the primary hot water. The temperature is stable and can be approximately a predetermined temperature), and if the primary hot water mixing ratio is α and the cold water mixing ratio is 1-α, TH
The primary hot water mixing ratio α can be solved from the formula of α + TL · (1−α) = TS−ΔTM. Feedforward control is performed by adjusting the mixing ratio of the primary hot water to the obtained α. If the primary hot water mixing ratio is adjusted to α, the cold water mixing ratio will be 1-α, the temperature of the hot water after mixing will be TS-ΔTM, the flow rate will be VM, and it will be heated by the minimum heating calorie QM to supply hot water. Hot water temperature of the vessel is the set temperature TS
This is because the temperature is adjusted to.

The above-mentioned unit further comprises a second temperature sensor for measuring the temperature of the cold water to be mixed, and the mixing ratio determining means incorporated in the unit is a measurement value of the first temperature sensor and the second temperature sensor. It is preferable to calculate the mixing ratio from According to this unit, both the primary hot water temperature measured by the first temperature sensor and the cold water temperature measured by the second temperature sensor are measured to calculate the mixing ratio, which is intended even if the cold water temperature changes. Feedforward control is possible.

The above-mentioned unit further includes a third temperature sensor for measuring the hot water temperature after mixing, and the mixing ratio determining means built in the unit is such that the measured value of the third temperature sensor is the supply temperature. It is preferable to correct the mixing ratio to match. According to this unit, feedback control can be performed using the measurement value of the third temperature sensor.
By using the feedforward control and the feedback control together, the hot water discharge temperature can be quickly adjusted to the set temperature and the state can be maintained.

Some water heaters can be operated so that hot water passing therethrough can be passed without being heated. In the case of a unit used for this type of water heater, it is preferable to add a means for instructing an operation to pass without heating in the water heater when the measured value of the first temperature sensor is equal to or higher than the set temperature. In this case, the mixing ratio determining means calculates and determines the mixing ratio from the measurement value of the first temperature sensor, where the hot water temperature after mixing reaches the set temperature. According to this method,
When the measured value of the temperature sensor is equal to or higher than the set temperature, the generated heat is preferentially used without being heated by the water heater. Since the hot water supplied to the water heater is adjusted to the set temperature, the secondary hot water adjusted to the set temperature is discharged even if it is not heated by the water heater.

The above-mentioned unit is provided with means for inputting, from the water heater, a set temperature, a current value of the minimum amount of heat to be heated, and a signal indicating whether or not the hot water passing therethrough can be passed through without heating. It is preferable. The set temperature is a temperature set by a person who needs hot water supply and may be reset. The minimum heating amount of heat is large from the start of combustion until the combustion becomes stable, becomes small when it becomes stable, and increases again immediately after switching the burner. If such information is constantly input to the unit, the temperature of the secondary hot water discharged from the water heater will be set to the set temperature against the change in the set temperature and the change in the minimum heating amount that changes depending on the combustion state. You can keep adjusting the temperature. When a signal indicating whether or not it is possible to perform an operation of passing hot water without heating it is input from the water heater, the hot water heater does not heat the power generator, but preferentially uses the generated exhaust heat to supply hot water. Can be selected.

Further, instead of inputting a signal from the water heater showing the present value of the minimum amount of heat to be heated and whether or not it is possible to pass the hot water passing therethrough without heating, the information is stored in the unit. Is also good. That is, a means for storing the minimum heating amount of the water heater connected to the unit and information indicating whether or not it is possible to perform an operation of passing hot water without heating the water heater is added to the above unit. It may be done. In this case, the time change pattern of the minimum heating heat quantity may be stored.

In the case of a unit which is used by being connected to a water heater capable of passing hot water without heating, that is, non-heating operation, the primary hot water and cold water are received and mixed to be supplied to the water heater. And a mixing ratio controller for adjusting the mixing ratio of the primary hot water and the cold water to be mixed, a first temperature sensor for measuring the temperature of the primary hot water before mixing, and a second temperature sensor for measuring the temperature of the cold water to be mixed. A third temperature sensor for measuring the temperature of the hot water after mixing, a flow rate sensor for measuring the flow rate of the hot water after mixing, and a minimum temperature rise obtained by dividing the minimum heating amount of the water heater by the measurement value of the flow rate sensor. Means for calculating a supply temperature to be supplied to the water heater by subtracting from the set temperature, and means for instructing the water heater to perform non-heating operation when the measured value of the first temperature sensor is equal to or higher than the set temperature, Equipped with mixing ratio determination means Cage, the mixture-ratio determining means,
(1) When the measured value of the first temperature sensor is equal to or higher than the preset temperature, (1-1) the mixing ratio of the hot water temperature after mixing from the measured values of the first temperature sensor and the second temperature sensor to the preset temperature. And (1-2) correct the mixing ratio of the measured value of the third temperature sensor to the set temperature, and (2) measure the measured value of the first temperature sensor at the set temperature or lower and at the supply temperature or higher. In some cases, (2-1) a mixing ratio at which the hot water temperature after mixing reaches the supply temperature is calculated from the measured values of the first temperature sensor and the second temperature sensor, and (2-2) the measured value of the third temperature sensor. Is corrected to a mixing ratio that matches the supply temperature, and (3)
When the measured value of the first temperature sensor is equal to or lower than the supply temperature, it is preferable to determine the mixing ratio that prohibits the mixing of cold water. In addition, "prohibition of mixing cold water" here means
It is preferable that the prohibition is complete, but it also includes the case where some cold water is mixed in the mixer.
That is, the “prohibition of mixing cold water” does not necessarily mean 100% prohibition (the same applies to the following description).

In the case of an operation in which hot water passing therethrough is not heated, that is, a unit which is used by being connected to a water heater which is not capable of non-heating operation, primary hot water and cold water are received, mixed and supplied to the water heater. Mixer, mixing ratio controller for adjusting mixing ratio of primary hot water and cold water to be mixed, first temperature sensor for measuring temperature of primary hot water before mixing, and second temperature sensor for measuring temperature of cold water to be mixed And a third temperature sensor for measuring the hot water temperature after mixing, a flow rate sensor for measuring the hot water flow rate after mixing, and a minimum temperature rise obtained by dividing the minimum heating heat quantity of the water heater by the measurement value of the flow sensor. It is provided with a means for calculating the supply temperature to be supplied to the water heater by subtracting the temperature from the set temperature, and a mixing ratio determining means, and the mixing ratio determining means (1) supplies the measured value of the first temperature sensor. When it is above the temperature, 1-1) A mixing ratio is calculated from the measured values of the first temperature sensor and the second temperature sensor so that the hot water temperature after mixing becomes the supply temperature, and (1-2) the measured value of the third temperature sensor is the supply temperature. It is preferable to correct the mixing ratio to match (2) and (2) determine the mixing ratio that prohibits the mixing of cold water when the measured value of the first temperature sensor is equal to or lower than the supply temperature. In this case, since the water heater is always heated, the mode of adjusting the temperature of the hot water supplied to the water heater to the set temperature is not adopted.

When the unit has the above-mentioned two control programs and the connected water heater is of a non-heating operation type, the program has a mode of adjusting the temperature of the hot water supplied to the water heater to the set temperature. If the connected water heater is a non-heating type that cannot be operated, a program that does not have a mode for adjusting the temperature of the hot water supplied to the water heater to the set temperature can be adopted. preferable.

When the unit of the present invention is used, it has a power generation system and a hot water supply system, and the hot water supply system inputs a waste heat generated from the power generation system and outputs primary hot water, and inputs the primary hot water to a set temperature. A cogeneration system having a means for outputting the temperature-controlled secondary hot water is constructed. The secondary hot water output means in this case is a means for mixing the primary hot water and the cold water at the specified mixing ratio, a water heater for heating the mixed hot water, and a first temperature for measuring the temperature of the primary hot water before mixing. A sensor, a flow rate sensor that measures the flow rate of hot water after mixing, and a minimum temperature rise obtained by dividing the minimum heating amount of the water heater by the measurement value of the flow sensor, and subtracting it from the set temperature and supplying it to the water heater. Calculate the supply temperature,
And a means for calculating a mixing ratio from the measured value of the first temperature sensor to the hot water temperature after mixing at the calculated supply temperature.
With this cogeneration system, it is not necessary to individually measure the flow rate of the primary hot water and the flow rate of the cold water, but by measuring the flow rate after mixing, the temperature of the secondary hot water discharged from the water heater can be adjusted to the set temperature. The feedforward control is performed.

The above cogeneration system includes
When an abnormality occurs in the hot water supply system, it is preferable to display an abnormality and to add a means for switching the heat exchanger that uses the exhaust heat of power generation. In this case, since the abnormality is displayed, the user can quickly recognize the abnormality, and at the time of abnormality, the waste heat of power generation is used by another heat exchanger,
Energy can be safely used without waste.

Further, it is preferable that a means for prohibiting the supply of the primary hot water to the water heater is added when an abnormality occurs in the device forming the cogeneration system. For example, the primary hot water supply pipe is provided with a solenoid valve or the like, and the solenoid valve is closed when an abnormality occurs in the device. In this case, very hot water can be prevented from being supplied.

Further, in the above cogeneration system, a means for prohibiting the supply of the primary hot water to the water heater when the primary hot water temperature is equal to or higher than a predetermined temperature may be added. In this case, very hot water can be prevented from being supplied.

[0026]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. First, the configuration of the cogeneration system according to the present invention will be described with reference to FIG. The cogeneration system according to the present invention is
A hot water supply system 90 and a system 41 for generating power using a fuel cell are provided. The hot water supply system 90 is the power generation system 4
The heat exchanger 45 that heats the hot water by using the exhaust heat generated by the power generation 1, the hot water storage tank 49 that stores the primary hot water heated by the waste heat generated by the heat exchanger 45, and the hot water storage tank 49 A hot water supply system 89 for adjusting the temperature of the primary hot water to a set temperature and supplying the hot water to the hot water required portion 83 is provided. The temperature-controlled hot water supply system 89 includes means 75 for mixing the primary hot water and tap water (cold water), and a water heater 81 for heating the mixed hot water. This cogeneration system uses a hot water tank 49
It is constructed by connecting the unit 88 between the water heater 81 and the water heater 81.

The fuel cell type power generation system 41 comprises a reformer (not shown), a fuel cell, etc. The reformer produces hydrogen gas from a hydrocarbon-based raw fuel. A high temperature is required to efficiently generate hydrogen, and it is heated by a gas burner or the like (not shown). Fuel cells generate electric power by reacting hydrogen gas with oxygen gas in the air. The fuel cell generates heat during power generation. A circulation path for a heat medium that cools the reformer and the fuel cell is formed around the reformer and the fuel cell. Power generation system 41
The cooling heat medium circulation passage inside extends to the outside and passes through the heat exchangers 45 and 43. A heat medium pump 42 is arranged in the heat medium circulation passage. The heat medium for collecting the exhaust heat of power generation is circulated in the heat medium circulation passage by the heat medium pump 42.

Primary hot water is stored in the hot water storage tank 49. A tap water (cold water) supply pipe 55 is connected to the hot water storage tank 49 via a pressure reducing valve 57. Arrow D1 on the tap water supply pipe 55
Tap water is supplied in the direction. The pressure reducing valve 57 is a hot water storage tank 49.
Function to keep the voltage below the withstand voltage. Also, the hot water storage tank 4
When the amount of primary hot water stored in 9 falls below a predetermined amount, a pressure difference occurs before and after the pressure reducing valve 57, and tap water is introduced in the direction of arrow D2. The amount of primary hot water stored in the hot water storage tank 49 is maintained at a constant amount. A hot water circulation passage 47 is connected between the hot water storage tank 49 and the heat exchanger 45. A hot water pump 46 is disposed in the hot water circulation passage 47. The primary hot water stored in the hot water storage tank 49 circulates in the hot water circulation passage 47 by the hot water pump 46.

The heat medium circulation passage and the hot water circulation passage 47 pass through the heat exchanger 45, the heat medium is cooled by the primary hot water, and the primary hot water is heated by the heat medium. Heated by the exhaust heat of power generation
The temperature of the primary hot water stored in
It does not correspond to the hot water temperature required at the hot water required portion 83. The temperature of the primary hot water in the hot water tank 49 is the hot water required point 83
It may be higher or lower than the hot water temperature required in. The heat medium circulation passage also passes through another heat exchanger 43, and the hot water heated here is used for heating, for example. Normally, hot water for heating is not circulated,
The generated heat is used to heat the primary hot water. When heating,
The primary hot water and the hot water for heating are heated by the exhaust heat of power generation. When an abnormality occurs in the hot water supply system 90, the hot water pump 46 is stopped, and the generated heat exhaust heats the hot water for heating.

A primary hot water supply pipe 51 is provided above the hot water storage tank 49.
Are connected. The primary hot water supply pipe 51 guides the primary hot water in the hot water storage tank 49 in the direction of arrow D4. A vacuum breaker 59 is arranged in the primary hot water supply pipe 51. The vacuum breaker 59 prevents tap water from flowing backward toward the hot water storage tank 49 when a negative pressure is generated in the primary hot water supply pipe 51. That is, when a negative pressure is generated in the primary hot water supply pipe 51, the vacuum breaker 59 automatically draws in air to eliminate the negative pressure. Further, the primary hot water supply pipe 51 is provided with an electromagnetic valve 67 whose on / off is controlled by an electromagnetic solenoid and a check valve 69. The primary hot water supply pipe 51 is provided with a first temperature sensor 71 that measures the temperature of the primary hot water before mixing. The primary hot water supply pipe 51 is connected to the mixed hot water supply pipe 77 via the hot water mixing ratio adjuster 65.
The warm water mixing ratio adjuster 65 adjusts the mixing ratio of warm water and mixes warm water with tap water (cold water).

The mixed hot water supply pipe 77 is a cold water mixing ratio controller 6.
It is also connected to the tap water pipe 53 via 3. A check valve 61 is inserted in the tap water pipe 53. The tap water pipe 53 is provided with a second temperature sensor 64 for measuring the temperature of cold water. The cold water mixing ratio adjuster 63 adjusts the mixing ratio of cold water (tap water) and mixes tap water with warm water.

The cold water mixing ratio adjuster 63 and the hot water mixing ratio adjuster 65 are combined to form a mixing means 75. The cold water mixing ratio adjuster 63 and the hot water mixing ratio adjuster 65 work together to adjust the mixing ratio. When the cold water mixing ratio controller 63 is 100% open, the hot water mixing ratio controller 65 is 100% closed, and the cold water mixing ratio controller 63 is
Is closed 100%, the warm water mixing ratio controller 65 is opened 100%. As a result, as shown in FIG. 9, the cold water mixing ratio adjuster 6
When 3 is 100% open and the warm water mixing ratio controller 65 is 100% closed, the cold water mixing ratio becomes 1.00 (100%) and the warm water mixing ratio becomes 0.00 (0%). On the other hand, the cold water mixture ratio adjuster 63 is closed 100% and the hot water mixture ratio adjuster 65 is set to 1
When it is opened at 00%, the cold water mixing ratio becomes 0.00 (0%) and the hot water mixing ratio becomes 1.00 (100%). The cold water mixing ratio and the hot water mixing ratio continuously change between 0.00 and 1.00, but the two are interlocked and, when added, always 1.0
It becomes 0. The hot water mixing ratio adjuster 65 is composed of a valve 65a having a substantially truncated cone shape and a valve drive portion 65b. The valve 65a can move up and down. The valve drive unit 65b moves the valve 65a in the vertical direction. By moving the valve 65a in the vertical direction, the flow path resistance between the primary hot water supply pipe 51 and the mixed hot water supply pipe 77 changes. When the valve 65a is at the uppermost position, the flow path is closed. The cold water mixing ratio adjuster 63 is composed of a substantially frustoconical valve 63a and a valve drive portion 63b.
The valve 63a can move up and down. The valve drive unit 63b moves the valve 63a in the vertical direction. By moving the valve 63a in the vertical direction, the flow path resistance between the tap water pipe 53 and the mixed hot water supply pipe 77 changes. When the valve 63a is at the uppermost position, the flow path is closed. When the valve 65a is in the uppermost position, the valve 63a is in the lowermost position, and when the valve 65a is in the lowermost position, the valve 63a is in the uppermost position.

The hot water mixed by the mixing means 75 is sent from the mixed hot water supply pipe 77 to the water heater 81. The mixed hot water supply pipe 77 has a third temperature sensor 73 for measuring the temperature of the mixed hot water supplied to the water heater 81 and a flow rate sensor 7 for measuring the flow rate of the mixed hot water supplied to the water heater 81.
8 are provided. Further, a relief valve 79 is arranged in the mixed hot water supply pipe 77. The relief valve 79 releases the water pressure when an abnormally high pressure occurs in the mixed hot water supply pipe 77. The relief valve 79 also serves as a drain plug. On the left side of the relief valve 79, a high-cut thermistor 87 that detects an abnormally high temperature
Is provided. When the high-cut thermistor 87 detects an abnormally high temperature, the solenoid valve 67 is closed to prevent the abnormally hot water from being supplied.

The hot water heater 81 heats the mixed hot water supplied from the mixed hot water supply pipe 77 to raise the temperature to a set temperature. The water heater 81 of the present embodiment is a type (through type or non-heating type) that does not heat even if a water flow is detected if the temperature of the mixed hot water supplied from the mixed hot water supply pipe 77 is higher than the set temperature. In the water heater 81, a water flow detection sensor 82 for detecting the presence / absence of water flow and an electronic control unit 84 for controlling the water heater are incorporated. A person who needs hot water supply can set the temperature of the secondary hot water by the remote controller 85. The non-heating type water heater 81 heats if the temperature of the mixed hot water supplied from the mixed hot water supply pipe 77 is lower than the set temperature. At this time, if the temperature difference from the set temperature is large, heating is performed with a large amount of heat, and if the set temperature is not reached even if the heating is performed with a large amount of heat, the flow rate is reduced to reach the set temperature. If the difference between the hot water temperature before heating and the set temperature is small and the flow rate is small, the heating amount is reduced. In this way, the water heater 81 regulates the temperature of the primary hot water to the set temperature and supplies the regulated secondary hot water to the hot water required portion 83. The minimum amount of heat for heating the water heater 81 is 4.4 kw, and it cannot be adjusted to less than this. The temperature rise temperature in this case changes depending on the flow rate, and the minimum temperature rise temperature at a large flow rate is small and the minimum temperature rise at a small flow rate is large. In addition, the minimum heating energy is larger than 4.4 kW at the start of combustion and 4.4 at the time of burner switching.
Greater than kW. The minimum amount of heat for heating when combustion is stable is 4.4
kw.

The cogeneration system according to this embodiment includes a control circuit section 86 whose details are shown in FIG. Note that, in FIG. 3, only the sensors and devices that characterize the present invention in the control circuit unit 86 are shown. Control circuit section 8
6 includes a CPU 102, a ROM 104, a RAM 106, an output port 108, and an input port 110. The CPU 102, ROM 104, and RAM 106 are connected to the output port 108 and the input port 11 by the bus 109.
Mutually connected to 0. CPU 102 is ROM1
In accordance with a control program stored in 04, various devices forming the cogeneration system are centrally controlled. The control program stored in the ROM 104 includes a process for determining the mixing ratio of the hot water mixing ratio adjuster 65 and the mixing ratio of the cold water mixing ratio adjuster 63 of the mixing means 75, adjusting the mixing ratio to the determined mixing ratio, and the water heater 81. It includes a process for determining and controlling the amount of heat for heating, a program for outputting the determined command data to each device through the output port 108, and the like. The RAM 106 is a main storage element used as a work memory, and stores various data such as temperature and input / output signals according to the execution of various programs.

At the input port 110, the first temperature sensor 7
The 1st, 2nd temperature sensor 64, the 3rd temperature sensor 73, the flow rate sensor 78, and the water heater 81 are connected. Moreover, the input port 110 can receive a signal from the remote controller 85 via the water heater 81. The first temperature sensor 71 converts the primary hot water temperature before mixing into a predetermined data signal and outputs it. The second temperature sensor 64 converts the temperature of the cold water mixed with the primary hot water into a predetermined data signal and outputs it. The third temperature sensor 73 converts the mixed hot water temperature into a predetermined data signal and outputs it. The first temperature sensor 71, the second temperature sensor 64, and the third temperature sensor 73 constantly measure the water temperature and constantly output the measurement results. The flow rate sensor 78 converts the hot water flow rate after mixing into a predetermined data signal and outputs it.
The water heater 81 outputs a signal indicating the set temperature set by the user using the remote controller 85, the minimum heating amount at the present time, and whether or not the water heater is a type capable of non-heating operation (through operation). . Each sensor 71, 73, 78 and water heater 81
The signal output from the input port 110 is received by the input port 110, and the signal received by the input port 110 is captured by the CPU 102, the ROM 104, and the RAM 106 via the bus 109. In the RAM 106, the temperature information measured by the first temperature sensor 71 and the third temperature sensor 73, and the flow rate sensor 78.
The flow rate information measured at is constantly updated (rewritten).

The output port 108 has a valve drive section 63b,
65b, the solenoid valve 67, and the water heater 81 are connected. The output port 108 can also output a signal to the remote controller 85 via the water heater 81. Valve drive parts 63b and 65b
Adjusts the mixing ratio of the mixing ratio adjusters 63a and 65a in conjunction with each other based on the drive signal output from the control circuit unit 86. As a result, the mixing ratio of the primary warm water and the cold water by the mixing means 75 is adjusted. The water heater 81 heats hot water based on the signal received from the control circuit unit 86.

Next, with reference to FIG. 4, the processing of the control circuit portion 86 at the time of hot water supply will be described. The control circuit unit 86 inputs the measurement value of the flow rate sensor 78 and monitors whether or not the flow rate above a predetermined value is measured (step S2). That is, the time when hot water supply is started at the hot water supply required portion 83 is monitored. When hot water supply is started, the water heater 81 is of a type (non-heated type) in which the hot water passing through the water heater can be passed without being heated (non-heating type), or if the hot water passes through, the minimum heating amount is always heated. It is determined whether it is a type (heating type) (step S4). The process of step S4 is performed by receiving a signal corresponding to the type of water heater 81. When the water heater 81 is the non-heating type, the set temperature set by the user by the remote controller 85 is updated to the latest set temperature (step S6). At this time, the current minimum heating amount of the water heater is also updated.

Next, in step S8, the first temperature sensor 7
The temperature of the primary hot water measured in 1 is compared with the set temperature.
If the temperature of the primary hot water is equal to or higher than the set temperature (step S
8 is YES), the water heater 81 is driven through, that is,
The non-heating operation is instructed (step S10). The process of step S10 is performed by outputting a heating operation prohibition signal to water heater 81. Next, the primary hot water mixing ratio x (that is, the cold water mixing ratio is 1-x) at which the hot water temperature after mixing reaches the set temperature is calculated (step S12). Here, if the temperature of the primary hot water measured by the first temperature sensor 71 is TH and the temperature of the cold water measured by the second temperature sensor 64 is TL, the hot water temperature after mixing is TH · x + T.
Since it should be L · (1-x), [TH · x + T
L * (1-x) = set temperature] is calculated.
When the primary hot water mixing ratio and the cold water mixing ratio are calculated in step S12 and the hot water mixing ratio adjuster 65 and the cold water mixing ratio adjuster 63 are adjusted so that the calculated mixing ratio is obtained,
The temperature of hot water supplied to the water heater 81 becomes the calculated set temperature.

Next, it is confirmed whether the temperature of the mixed hot water mixed by the above-mentioned feedforward control is the set temperature (step S14). In this processing, it is determined whether the measured value of the third temperature sensor 73 and the set temperature substantially match or do not substantially match. In this case, if it is within ± 1 ° C. from the set temperature, it is determined that they are almost the same.
If the measured value of the third temperature sensor 73 and the set temperature substantially match, YES is determined in step S14. If YES is determined in the step S14, the process returns to the step S6, and when the set temperature is changed or when the first temperature sensor 71 is used.
Wait for changes in the measured values at. In this case, the water heater 81 does not heat, but the temperature has already been adjusted to the set temperature when the water heater 81 enters. The water heater 81 supplies the secondary hot water whose temperature has been adjusted to the set temperature without heating. When the measured value of the third temperature sensor 73 and the set temperature do not match and the error is large (NO in step S14),
The measured value of the third temperature sensor 73 and the set temperature are compared (step S16). When the measured value of the third temperature sensor 73 is higher than the set temperature (YES in step S16),
The hot water mixing ratio is decreased and the cold water mixing ratio is increased (step S20). As a result, the hot water temperature after mixing falls,
Close to the set temperature. Moreover, when the measured value of the third temperature sensor 73 is lower than the set temperature (NO in step S16).
In the case of), the hot water mixing ratio is increased and the cold water mixing ratio is decreased (step S18). As a result, the hot water temperature after mixing rises and approaches the set temperature. Steps S18 and S20
Then, the process returns to step S14 again, and it is confirmed whether the hot water temperature after mixing matches the set temperature. Feedback control is repeated until they match. In this case, the temperature of the mixed hot water is adjusted to the set temperature in a short time by the feedforward control of step S12, and the mixing ratio calculated by the feedforward control is corrected by the feedback control of step S14 and thereafter to mix the mixed hot water. The temperature is controlled so that it closely matches the set temperature.

When the temperature of the primary hot water compared in step S8 is lower than the set temperature (NO in step S8)
Compares the measured value of the first temperature sensor 71 with the supply temperature (step S22). The supply temperature here is a value obtained by subtracting the minimum temperature rise by the water heater 81 from the set temperature updated in step S6, and the minimum temperature rise is the minimum heating amount of the water heater at that time. It is a value obtained by converting the value divided by the flow rate measured by the flow rate sensor 78 into a unit of temperature. If the flow rates are the same, the greater the minimum heating heat amount, the greater the minimum temperature rise temperature. Immediately after the start of combustion or immediately after switching the burner, the minimum heating amount is large. FIG. 8 schematically shows this, and shows that the minimum heating amount of heat and the minimum temperature rise change according to the combustion state and flow rate of the water heater. First
When the measured value of the temperature sensor 71 is equal to or higher than the supply temperature (YES in step S22), the primary hot water mixing ratio at which the hot water temperature after mixing becomes the supply temperature is calculated, and the hot water mixing is performed so as to be the mixing ratio. Ratio adjuster 65 and cold water mixing ratio adjuster 63
Is adjusted (step S24). In the processing of this step S24, the same processing as the above-mentioned step S12 is performed. However, in step S12, the mixing ratio is calculated so as to be the set temperature, whereas in step S24 the mixing ratio is calculated so as to be the supply temperature.

In step S24, when the mixing ratio is adjusted, it is determined whether the hot water temperature after mixing substantially matches the supply temperature or does not substantially match. In this case, if it is within ± γ (about 1 ° C.) from the supply temperature, it is determined that they substantially match (step S26). Y in step S26
In the case of ES, the process returns to step S6 and stands by in case the set temperature is changed or the measurement value of the first temperature sensor 71 is changed. In this case, the water heater 81 can be heated to the set temperature by heating with the minimum heating amount, and the secondary hot water whose temperature has been adjusted to the set temperature is supplied. The water heater 81 is operated with the minimum heating amount of heat, and the heat amount of power generation exhaust heat is preferentially used. If NO in step S26, the supply temperature is compared with the measurement value of the third temperature sensor 73 (step S28). When the measured value of the third temperature sensor 73 is higher than the supply temperature (YES in step S28), the hot water mixing ratio is decreased and the cold water mixing ratio is increased to bring the hot water temperature after mixing close to the supply temperature. (Step S3
0). When the measured value of the third temperature sensor 73 is lower than the supply temperature (NO in step S28), the hot water mixing ratio is increased and the cold water mixing ratio is decreased to change the hot water temperature after mixing to the supply temperature. (Step S32). When the processing of steps S30 and S32 is performed, step S2
Check 6 again. Feedback control is repeated until they match. In this case, step S24
The feed-forward control of No. 1 adjusts the temperature of the mixed hot water to the supply temperature in a short time, and the feedback control after step S26 corrects the mixing ratio calculated by the feed-forward control to keep the temperature of the mixed hot water at the supply temperature. Controlled to match.

In step S22, the measured value of the first temperature sensor 71 is compared with the supply temperature. If the measured value is lower than the supply temperature (NO in step S22), the cold water mixing ratio is set to 0% and the primary warm water is set. Use only (step S3
4). As a result, the amount of heat obtained from the exhaust heat of power generation is preferentially used, and the insufficient amount of heat is supplemented by the water heater.

Next, with reference to FIG. 6, the temperature control process in the case of the water heater capable of non-heating operation will be described. If the primary hot water temperature is higher than the set temperature, it is mixed with cold water to adjust the temperature to the set temperature and is not heated in the water heater (arrow a). When the temperature is lower than the set temperature and higher than the supply temperature, the temperature is lowered to the supply temperature by mixing with cold water (arrow b). After that, the water temperature rises to the minimum heating temperature in order for the water heater to heat at the minimum heating flow rate,
As a result, the temperature is adjusted to the set temperature (arrow c). If it is lower than the supply temperature, it is not mixed with cold water (arrow d), and is heated by the amount of heat necessary to reach the set temperature from there, and the temperature is adjusted to the set temperature (arrow e).

Next, with reference to FIG. 5, a process performed by the control circuit portion 86 when the water heater 81 is a heating type will be described. When the water heater 81 is a heating type (step S in FIG. 4)
(NO in 4), the set temperature set by the user is updated to the latest set temperature by the remote controller 85 as in step S6 described above (step S40). Next, the supply temperature and the measurement value of the first temperature sensor 71 are compared (step S4).
2). When the measured value of the first temperature sensor 71 is equal to or higher than the supply temperature (YES in step S44), the same processing as steps S24 to S32 described above is performed (steps S44 to S52). In addition, the first temperature sensor 7
When the measured value of 1 is lower than the supply temperature (NO in step S42), the mixing ratio of hot water is set to 100%, and mixing of cold water is prohibited. When the water heater 81 is a heating type, the mixing ratio is not calculated so that the mixed hot water temperature becomes the set temperature. This is because hot water is always heated by the water heater 81, and hot water exceeding the set temperature is supplied. FIG. 7 shows a temperature control process by a water heater of a type that constantly heats. In this case, if the temperature is equal to or higher than the supply temperature, it is mixed with cold water and lowered to the supply temperature (arrow f), from which the minimum heating amount is reached. Heat and adjust to the set temperature. If it is lower than the supply temperature, it is not mixed with cold water (arrow d), and is heated from there by the amount of heat necessary to reach the set temperature and adjusted to the set temperature (arrow e).

In the cogeneration system according to this embodiment, the first temperature sensor 71 and the second temperature sensor 64 are provided.
The primary hot water and the cold water are mixed by the feedforward control based on the measured value of 1 and the feedback control based on the measured value of the third temperature sensor 73 is also performed. That is, when the temperature of the primary hot water supplied from the hot water storage tank 49 changes at the start of hot water supply or after the start of hot water supply,
When the set temperature is changed after the hot water supply is started, the feedforward control is immediately performed, and the hot water having the set temperature is supplied in a short time after the hot water supply is started. Further, it is confirmed whether or not the feedforward-controlled hot water temperature matches the set temperature or the supply temperature, and if they do not match, feedback control is performed to finely adjust the mixing ratio.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. For example, in the above embodiment, the second temperature sensor 64 is provided in the tap water pipe 53, but the width of the temperature change of tap water is
Approximately "cold water temperature is fixed at a specified value" because it is much smaller than the width of the temperature change of the primary hot water.
Can also be If this approximation is allowed, then the second temperature sensor 64 is not needed. Further, in the present embodiment, the third temperature sensor 73 for measuring the hot water temperature after mixing is used in order to use the feedback control together, but the feedforward control during hot water supply can be continued. In this case, 3 temperature sensor 73 is not required. Further, in the above cogeneration system, an error display may be displayed on the remote controller 85 when a sensor wire breakage, a short circuit, a failure of the mixing means 75 and other devices occur. This error display is performed by outputting an error detection signal from the control circuit unit 86 to the remote controller 85. When an error occurs, the water solenoid valve 67
May be closed, or the operation of the pump 46 may be stopped to control the heating of the primary hot water. In this case, the power generation wastewater is used by the other heat exchanger 43 to heat the hot water 44 for another purpose. Further, in the above embodiment, the mixing means 75 is of a type that individually changes the opening degree of the hot water pipe and the cold water pipe, but a 3-port valve that inputs hot water and cold water and outputs mixed water is used. Thus, a type in which the hot water mixing ratio and the cold water mixing ratio change mechanically in conjunction can be used.
In the present embodiment, the mixing ratio adjusting device and the mixing device are used as the mixing means 75.
However, the mixing ratio adjuster and the mixer may be separately configured. Further, instead of the method of generating power by the fuel cell, a method of rotating the generator by the engine to generate power may be used. Also in this case, the exhaust heat of power generation is generated. Further, the information is not limited to the method of receiving a non-heating type signal or a heating type signal from the water heater 81 or the current value of the minimum heating heat amount, and the information may be stored in advance. RAM, for example
At 106, information on whether the water heater is of a non-heating type or a heating type and time change from the time of hot water supply of the minimum heating heat amount are stored. Even in this case, the mixing ratio can be determined according to the type of the water heater and the change in the minimum heating amount. Further, the mixing means 75 of the present embodiment can set the cold water mixing ratio to 0%, but it does not have to be 0% in a perfect sense. That is, the mixing means 75 cannot completely prohibit the mixing of cold water, and the present invention can be applied to the case where a small amount of cold water is mixed. Also,
The technical elements described in the present specification or the drawings exert technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technique illustrated in the present specification or the drawings achieves a plurality of purposes at the same time, and achieving the one purpose among them has technical utility.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cogeneration system according to a conventional technique.

FIG. 2 is a schematic configuration diagram of a cogeneration system according to the present invention.

FIG. 3 is a block diagram of a control circuit unit and its periphery.

FIG. 4 is a flowchart of a process performed by a control circuit unit.

FIG. 5 is a flowchart of processing performed by the control circuit unit.

FIG. 6 schematically shows a temperature adjustment process by a non-heating type water heater.

FIG. 7 schematically shows a temperature control process by a heating type water heater.

FIG. 8 schematically shows that the minimum heating amount of heat changes with time, and the minimum heating temperature further changes according to the flow rate.

FIG. 9 shows how the hot water mixing ratio and the cold water mixing ratio change in conjunction with each other.

[Explanation of symbols]

41 .. Fuel cell power generation system 45 ··· Heat exchanger 49 ... Hot water storage tank 51 ... Primary hot water supply pipe 53 .. Tap water pipe 63..Cold water mixing ratio controller 63a ... Valve 63b ... Valve drive unit 64 ... Second temperature sensor 65 ・ ・ Hot water mixing ratio controller 65a ... Valve 65b ... Valve drive unit 67 ... Solenoid valve 71 ... First temperature sensor 73 ... Third temperature sensor 75. Mixing means 77 ··· Mixed hot water supply pipe 78 ... Flow rate sensor 81..Water heater 86 .. Control circuit unit 88 ... Unit

Claims (12)

[Claims] 1. A unit for constructing a cogeneration system by connecting between a hot water storage tank of primary hot water heated by exhaust heat of power generation and a water heater for discharging secondary hot water adjusted to a set temperature. , A mixer for receiving and mixing the primary hot water and the cold water to supply to the water heater, a mixing ratio controller for adjusting the mixing ratio of the primary hot water and the cold water to be mixed, and a first temperature for measuring the temperature of the primary hot water before mixing A temperature sensor, a flow rate sensor that measures the flow rate of hot water after mixing, and the minimum heating temperature obtained by dividing the minimum heating heat amount of the water heater by the measurement value of the flow sensor, and subtracting it from the set temperature to supply it to the water heater. Means for calculating a supply temperature to be performed and determining a mixing ratio from the measured value of the first temperature sensor to a hot water temperature after mixing to become the calculated supply temperature. 2. A second temperature sensor for measuring the temperature of cold water to be mixed is further provided, and the mixing ratio determining means calculates the mixing ratio from the measured values of the first temperature sensor and the second temperature sensor. The unit according to claim 1. 3. A third temperature sensor for measuring the hot water temperature after mixing is further provided, and the mixing ratio determining means corrects the mixing ratio of the measured value of the third temperature sensor to the supply temperature. The unit according to claim 1 or 2. 4. The mixing ratio determining means, when the measurement value of the first temperature sensor is equal to or higher than the set temperature, the mixing ratio of the hot water temperature after mixing from the measurement value of the first temperature sensor becomes the set temperature. When the measured value of the first temperature sensor is equal to or higher than the preset temperature, a means for instructing the operation of passing the hot water without heating is calculated. The unit according to any one of claims 1 to 3, which is added. 5. A means for inputting from the water heater a signal indicating the set temperature, the current value of the minimum amount of heat to be heated, and a signal indicating whether or not an operation of passing hot water without heating can be performed is added. The unit according to any one of claims 1 to 4. 6. A means for storing the minimum heating heat quantity of the connected water heater and information indicating whether or not it is possible to pass the hot water passing through the water heater without heating the hot water. Item 5. A unit according to any one of items 1 to 4. 7. A cogeneration system that is connected between a hot water storage tank of primary hot water heated by exhaust heat of power generation and a water heater capable of non-heating operation for discharging secondary hot water whose temperature has been adjusted to a set temperature. It is a unit that builds a mixer that receives and mixes primary hot water and cold water and supplies it to the water heater, a mixing ratio controller that adjusts the mixing ratio of the primary hot water and cold water to be mixed, and the primary hot water before mixing. A first temperature sensor for measuring temperature, a second temperature sensor for measuring temperature of mixed cold water, a third temperature sensor for measuring hot water temperature after mixing, and a flow sensor for measuring hot water flow rate after mixing, A means for calculating the supply temperature to be supplied to the water heater by subtracting the minimum heating temperature obtained by dividing the minimum heating amount of the water heater by the measured value of the flow rate sensor, and the measurement of the first temperature sensor. If the value is above the set temperature If that includes means for instructing the non-heating operation to the water heater, equipped with a mixing ratio determination unit, the mixing ratio determining means (1)
When the measured value of the first temperature sensor is equal to or higher than the set temperature, (1-1) calculate a mixing ratio from the measured values of the first temperature sensor and the second temperature sensor, where the hot water temperature after mixing becomes the set temperature. , (1-2) the measured value of the third temperature sensor is corrected to a mixing ratio that matches the set temperature, and (2) the measured value of the first temperature sensor is equal to or lower than the set temperature and equal to or higher than the supply temperature, (2-1) A mixing ratio is calculated from the measured values of the first temperature sensor and the second temperature sensor so that the hot water temperature after mixing becomes the supply temperature, and (2-2) the measured value of the third temperature sensor is supplied to the supply temperature. The mixing ratio is corrected to match the temperature, and (3) when the measured value of the first temperature sensor is equal to or lower than the supply temperature,
A unit that determines a mixing ratio that prohibits mixing of cold water. 8. A cogeneration system, which is connected between a hot water storage tank for primary hot water heated by exhaust heat from power generation and a water heater for discharging secondary hot water whose temperature is adjusted to a preset temperature by heating hot water passing therethrough. A unit that constructs the system, a mixer that receives and mixes primary hot water and cold water to supply to the water heater, a mixing ratio controller that adjusts the mixing ratio of the primary hot water and cold water to be mixed, and primary hot water before mixing. A first temperature sensor for measuring the temperature of, a second temperature sensor for measuring the temperature of cold water to be mixed, a third temperature sensor for measuring the temperature of hot water after mixing, and a flow sensor for measuring the flow rate of hot water after mixing , A means for calculating a supply temperature to be supplied to the water heater by subtracting the minimum heating temperature obtained by dividing the minimum heating amount of the water heater by the measured value of the flow rate sensor from the set temperature, and a mixing ratio determining means. Prepare and determine the mixing ratio Is, (1)
When the measured value of the first temperature sensor is equal to or higher than the supply temperature, (1-1) calculate a mixing ratio from the measured values of the first temperature sensor and the second temperature sensor where the hot water temperature after mixing becomes the supply temperature. , (1-2) correct the mixing ratio of the measured value of the third temperature sensor to the supply temperature, and (2) prohibit the mixing of cold water when the measured value of the first temperature sensor is equal to or lower than the supply temperature. A unit for determining a mixing ratio to be used. 9. A cogeneration system having a power generation system and a hot water supply system, the hot water supply system inputting waste heat generated from the power generation system to output primary hot water and adjusting the set temperature by inputting the primary hot water. The secondary hot water output means has means for outputting heated secondary hot water, and the secondary hot water output means is a means for mixing the primary hot water and the cold water at a specified mixing ratio, a water heater for heating the mixed hot water, and a pre-mixing device. The first temperature sensor that measures the temperature of the primary hot water, the flow sensor that measures the hot water flow rate after mixing, and the minimum heating temperature obtained by dividing the minimum heating amount of the water heater by the measurement value of the flow sensor. Means for calculating a supply temperature to be supplied to the water heater by subtracting it from the set temperature, and calculating a mixing ratio of the hot water temperature after mixing to the calculated supply temperature from the measured value of the first temperature sensor. Generation system. 10. When an abnormality occurs in the hot water supply system,
10. The cogeneration system according to claim 9, further comprising means for switching the heat exchanger that uses the exhaust heat of power generation to display an abnormality. 11. A means for prohibiting the supply of the primary hot water to the water heater when an abnormality occurs in a device constituting the cogeneration system, according to claim 9 or 10. The cogeneration system described in. 12. The coater according to claim 9, further comprising means for prohibiting the supply of the primary hot water to the water heater when the temperature of the primary hot water is equal to or higher than a predetermined temperature. Generation system.