JP2007322071A - Cogeneration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cogeneration system realizing high heat efficiency without causing malfunctions in operation of a power generation unit even when a heat load fluctuates during operation. <P>SOLUTION: Hot water sent to the power generation unit 150 from a lower part of a hot water storage tank 14 is heated by power generation heat, and returned to an upper part of the hot water storage tank 14. Hot water sent from the hot water storage tank 14 to a burner part 68 and heated therein is used in heat exchange with a heating medium in a heat exchanger 114. The heating medium heated by the heat exchange is used in heating in a heating terminal unit 110. A return location of the hot water cooled by the heat exchange is changed in response to a temperature detected by a heat exchanger outlet thermistor 90. If the detected temperature is sufficiently high, the hot water is returned to the higher part of the hot water storage tank 14. If the detected temperature is sufficiently low, the hot water is returned to the lower part of the hot water storage tank 14. If the detected temperature is unsatisfactory, the hot water is by-passed around the hot water storage tank 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention stores hot water heated by generated heat in a hot water storage tank, supplies hot water using the hot water stored in the hot water storage tank, and further uses the hot water stored in the hot water storage tank. The present invention relates to a cogeneration system that heats a heat medium and performs heating and bathing. In particular, the present invention relates to a cogeneration system in which hot water in a hot water storage tank is heated by a heat source machine as necessary, and the hot water heated by the heat source machine is used for hot water supply or other purposes (heating, bathing, etc.).

  A cogeneration system that stores hot water heated by generated heat and supplies it is known. Hot water heated by the generated heat is stored in a hot water storage tank. If hot water that is hotter than the hot water temperature (hot water set temperature) required at the hot water usage point during hot water operation is stored in the hot water storage tank, the hot water sent from the hot water tank and tap water (cold water) are mixed by the mixing means. The hot water is then cooled to the required temperature (non-combustion hot water supply operation). If hot water at a temperature lower than the hot water temperature required at the location where hot water is used (hot water supply set temperature) is stored in the hot water storage tank, it is necessary to heat and supply hot water with a heat source machine (combustion hot water operation). The amount of heat required is less than when (cold water) is heated with a heat source machine to supply hot water. Cogeneration systems are highly energy efficient.

  In the above-mentioned cogeneration system, not only the hot water stored in the hot water storage tank is used for hot water supply, but also the amount of heat stored in the hot water storage tank can be used for heating or bathing. By increasing the use of the generated heat recovered from the power generation unit to the hot water storage tank, the overall energy efficiency is further improved. Such a cogeneration system is described in Patent Documents 1 to 3, for example.

Japanese Patent Laid-Open No. 2004-361028 JP 2001-304688 A JP 2004340404 A

  Depending on the type and size of the power generation unit, the temperature of the hot water stored in the hot water storage tank may be lower than the temperature of the hot water required for heating or bathing. For example, in the case of a cogeneration system using a general polymer electrolyte fuel cell, the temperature of the hot water from which the generated heat is recovered is about 60 ° C., which is insufficient for use in heating, bathing, etc. Temperature. In such a case, it is necessary to use the heat source machine used in the combustion hot water supply operation, to heat the hot water stored in the hot water storage tank, and to use the heated hot water for heating or reheating the bath.

  When using a common heat source for hot water supply and other purposes (heating, bathing, etc.), heat the hot water stored in the hot water storage tank with the heat source and exchange heat with the hot water heated by the heat source. It is effective to heat the heat medium and return the hot water heat-exchanged with the heat medium to the upper part of the hot water storage tank. With this configuration, during heating operation and reheating operation, the hot water in the hot water storage tank is heated to the required temperature by the heat source device, and the heat medium is heated to the required temperature by exchanging heat with the heated hot water, Heating or bathing can be performed using the heated heat medium. During hot water supply operation, the hot water in the hot water storage tank is heated to the required temperature by the heat source device, the hot water heated to the required temperature is returned to the upper part of the hot water storage tank, and hot water is supplied from the upper part of the hot water storage tank. Hot water can be supplied. According to such a configuration, even when the heat load for uses other than hot water fluctuates during hot water supply and the temperature of hot water returning to the upper part of the hot water tank fluctuates, the upper part of the hot water tank serves as a buffer tank. Since it functions, the hot water temperature can be stabilized.

  In the above system, during the heating operation or the bath reheating operation, the hot water cooled by exchanging heat with the heat medium is returned to the upper part of the hot water storage tank. The amount of decrease in the hot water temperature due to heat exchange with the heat medium varies depending on the heat load of the heating operation or the bath reheating operation. If the fluctuation range of the decrease width of the hot water temperature is slight, the upper part of the hot water storage tank functions as a buffer tank, so that there is no significant influence on the utilization efficiency of the heat storage. However, if the fluctuation range of the temperature drop of the hot water temperature is large and a situation where low-temperature hot water flows into the upper part of the hot water storage tank occurs, the temperature stratification state in the hot water storage tank collapses and the utilization efficiency of the heat storage decreases.

  If the temperature of the hot water drops greatly due to the heat exchange with the heat medium, and the hot water is returned to the upper part of the hot water tank, the temperature stratification state in the hot water tank will collapse. Return the hot water to the lower part of the hot water tank. By setting it as a structure, the temperature stratification state in a hot water storage tank can be maintained. However, since the water stored in the lower part of the hot water storage tank plays a role as cooling water supplied to the power generation unit, it needs to be as low as tap water. If the temperature of the hot water cooled by heat exchange with the heat medium is high enough to be used as the cooling water for the power generation unit, returning the hot water to the bottom of the hot water storage tank will cause a malfunction in the operation of the power generation unit. There is a risk that. In addition, when hot water that is high in temperature is allowed to flow into the lower part of the hot water storage tank to be used as cooling water for the power generation unit, convection occurs in the hot water storage tank, and the temperature stratification state in the hot water storage tank collapses, reducing the utilization efficiency of heat storage. There is a risk that.

  As described above, in a cogeneration system that collects the heat generated by the power generation unit, stores it in a hot water storage tank, and uses the stored heat for hot water supply and other purposes (heating, bathing, etc.), heat is generated during operation. Even when the load fluctuates, there is a demand for a system capable of realizing high thermal efficiency by causing no trouble in the operation of the power generation unit and maintaining the temperature stratification state in the hot water storage tank.

  The present invention has been made in view of the above problems. An object of the present invention is to provide a cogeneration system capable of realizing high thermal efficiency without causing trouble in the operation of the power generation unit even when the thermal load fluctuates during operation.

  The present invention heats water with the generated heat generated in the power generation unit, stores the heated hot water, supplies hot water using the stored hot water, and further uses the stored hot water. It is embodied in a cogeneration system that can heat the heating medium. The cogeneration system includes a hot water storage tank for storing hot water, power generation heat recovery means for returning the hot water stored in the lower part of the hot water storage tank to the power generation unit and returning the hot water heated by the generated heat to the upper part of the hot water storage tank. Heat source that heats, hot water forward route that sends hot water stored in the hot water storage tank to the heat source device, first hot water return passage that returns the hot water heated by the heat source device to the upper part of the hot water storage tank, and hot water usage from the upper part of the hot water storage tank The hot water supply means for supplying hot water to the location, the heat exchanger for exchanging heat between the hot water passing through the first hot water return path and the heat medium, and the temperature of the hot water passing through the first hot water return path downstream from the heat exchanger are detected. A temperature sensor, a second hot water return path that branches from the first hot water return path downstream from the temperature sensor and directs the hot water to the hot water forward path without passing through the hot water storage tank, and a branch from the first hot water return path downstream from the temperature sensor A third hot water return path for guiding hot water to the lower part of the hot water storage tank, a hot water flow path via the heat exchanger, a first flow path for flowing into the upper part of the hot water storage tank via the first hot water return path, There is provided switching means for switching to either the second flow path flowing into the warm water forward path via the 2 hot water return path or the third flow path flowing into the lower part of the hot water storage tank via the 3rd hot water return path. . The switching means switches to the first flow path when the temperature detected by the temperature sensor is higher than the first predetermined temperature, and when the temperature detected by the temperature sensor is lower than the first predetermined temperature and higher than the second predetermined temperature. When the temperature detected by the temperature sensor is lower than the second predetermined temperature, the third channel is switched.

  In the above system, hot water is sent from the lower part of the hot water storage tank to the power generation unit, and the hot water heated by the generated heat is returned to the upper part of the hot water storage tank, whereby the hot water heated by the generated heat is stored in the hot water storage tank. A temperature stratification state is formed inside the hot water tank, and hot hot water is stored in the upper part of the hot water tank. Hot water supply using the generated heat of the power generation unit can be performed by supplying hot water to the hot water use location.

  In the above system, when the hot water temperature stored in the upper part of the hot water storage tank is low and lower than the hot water temperature required at the hot water use location, the hot water in the upper part of the hot water storage tank is heated with a heat source machine. Hot water can be supplied. In this case, the hot water in the hot water storage tank is sent to the heat source machine via the hot water outgoing path, and the hot water heated by the heat source machine flows into the upper part of the hot water storage tank via the first hot water return path. Thus, hot water heated to the hot water temperature required at the hot water use location is supplied from the upper part of the hot water storage tank. With such a configuration, since the upper part of the hot water storage tank functions as a buffer tank, the temperature of the hot water supplied to the hot water use location can be stabilized.

  When performing the heating operation or the reheating operation of the bath with the above system, hot water is sent from the hot water storage tank to the heat source machine, and the hot water is heated to a required temperature. And the heated warm water is heat-exchanged with a heat medium with a heat exchanger, and a heat medium is heated. Using the heated heat medium, it is possible to perform a heating operation or a bath reheating operation. In the above system, the return destination of the hot water cooled by heat exchange with the heat medium is determined based on the temperature of the hot water. The temperature of the hot water cooled by heat exchange with the heat medium is detected by a temperature sensor. When the temperature detected by the temperature sensor is higher than the first predetermined temperature, the hot water is returned to the upper part of the hot water storage tank via the first hot water return path. Accordingly, since hot water having a temperature higher than the first predetermined temperature flows into the upper part of the hot water storage tank, if an appropriate value is set for the first predetermined temperature, the temperature stratification state inside the hot water storage tank may collapse. Absent. When the temperature detected by the temperature sensor is lower than the second predetermined temperature, the hot water is returned to the lower part of the hot water storage tank via the third hot water return path. As a result, hot water having a temperature lower than the second predetermined temperature flows into the lower part of the hot water storage tank. If an appropriate value is set for the second predetermined temperature, the hot water in the lower part of the hot water storage tank is kept at a low temperature, and there is no problem with the operation of the power generation unit. Further, when the temperature detected by the temperature sensor is lower than the first predetermined temperature and higher than the second predetermined temperature, the hot water bypasses the hot water storage tank and flows into the hot water forward path. As a result, hot water having a halfway temperature that is low in temperature to return to the upper part of the hot water storage tank but high in temperature to return to the lower part of the hot water storage tank flows into the hot water forward path without flowing into the hot water storage tank. The temperature stratification of the hot water storage tank does not collapse.

  In the above system, if the heat load such as heating or bathing changes during operation, the amount of heat given from the hot water to the heat medium in the heat exchanger increases and decreases, and the temperature of the hot water after heat exchange with the heat medium fluctuates. . Even in such a case, according to the above system, since the return destination of the hot water is switched based on the hot water temperature after heat exchange with the heat medium, the temperature stratification state in the hot water storage tank is not destroyed. Use efficiency of heat storage can be increased. Moreover, the temperature of the lower part of the hot water storage tank can be kept low, and there is no problem in the operation of the power generation unit.

In the cogeneration system, it is preferable that the heat medium circulates between the heating terminal and the heat exchanger.
By setting it as such a structure, it can heat with a heating terminal machine using the heat medium heated by heat exchange with the warm water heated with the heat-source equipment.

The above-mentioned cogeneration system further includes a reheating heat exchanger that exchanges heat between the hot water sent from the bath tub and the heat medium, and the heat medium is interposed between the heat exchanger and the reheating heat exchanger. It is preferable to circulate.
By setting it as such a structure, the bath can be refurbished using the heat medium heated by heat exchange with the warm water heated with the heat source machine.

  According to the cogeneration system of the present invention, even when the thermal load fluctuates during operation, high thermal efficiency can be realized without causing a malfunction in the operation of the power generation unit.

Hereinafter, preferred embodiments of the present invention will be described.
(Form 1) The said warm water outward path is connected to the intermediate part of the hot water storage tank.
(Mode 2) The heating medium is water.

  An embodiment embodying the cogeneration system of the present invention will be described with reference to the drawings. As shown in FIG. 1, the cogeneration system of the present embodiment includes a power generation unit 150, a hot water supply unit 10, and a thermal load 108.

  The power generation unit 150 includes a fuel cell (not shown), a reformer (not shown), a heat medium circulation path 152, and a heat recovery heat exchanger 154. The fuel cell generates power by reacting hydrogen gas generated in the reformer with oxygen in the air. Generated heat is generated along with power generation, and the heat medium in the heat medium circulation path 152 is heated by the generated heat. The heat of the heat medium in the heat medium circulation path 152 is input to the heat recovery heat exchanger 154.

The hot water supply unit 10 includes a hot water storage unit 12, a burner unit 68, a heating heat exchanger 114, a bath heat exchanger 124, various flow paths, a controller 146, and the like.
The controller 146 stores a control program. The controller 146 receives operation signals from the remote controller 148, detection signals from various flow sensors described below, detection signals from various thermistors, and the like. The controller 146 processes the input signal with a control program, and controls various pumps, various valves, a burner, and the like described below.

The hot water storage section 12 includes a hot water storage tank 14, a first tank thermistor 16, a second tank thermistor 18, a third tank thermistor 20, and a fourth tank thermistor 22. The tank thermistors 16, 18, 20, and 22 are arranged substantially evenly in the vertical direction, and detect the temperature of hot water at each position in the hot water storage tank 14. Detection signals from the tank thermistors 16, 18, 20, and 22 are output to the controller 146.
A water supply path 24 for supplying tap water to the hot water storage tank 14 is connected to the bottom of the hot water storage tank 14. A pressure reducing valve 26, a water supply thermistor 28, a water supply amount sensor 30, a water supply amount servo 32, and a mixing servo 34 are interposed in the water supply path 24. The pressure reducing valve 26 is disposed in the vicinity of the upstream end of the water supply path 24. The pressure reducing valve 26 adjusts the feed water pressure. When the pressure on the downstream side of the pressure reducing valve 26 decreases, the pressure reducing valve 26 opens and tries to maintain the pressure at a predetermined pressure regulation value. For this reason, when the hot water in the hot water storage tank 14 decreases or the mixing servo 34 described later opens, tap water is supplied by the action of the pressure reducing valve 26. The water supply thermistor 28 detects the temperature of the tap water supplied. The water supply amount sensor 30 detects the flow rate of tap water supplied. The detection signal of the water supply thermistor 28 and the detection signal of the water supply amount sensor 30 are output to the controller 146. Each of the water supply amount servo 32 and the mixing servo 34 has a built-in stepping motor, and when this is driven, the opening degree is adjusted to change the flow rate. The water supply amount servo 32 adjusts the flow rate of the tap water supplied. The opening degree of the water supply servo 32 is controlled by the controller 146. The mixing servo 34 is disposed at a connection portion between the water supply path 24 and the mixing path 36. The mixing servo 34 will be described in detail later.
A drainage path 38 is connected to the downstream side of the mixing servo 34 in the water supply path 24. The other end of the drainage path 38 is connected to the pressure release path 42. The pressure release path 42 is open to the outside of the cogeneration system. A drain valve 40 is interposed in the drain path 38. The drain valve 40 is manually opened and closed. When the drain valve 40 is opened, the hot water in the hot water storage tank 14 is drained through the drain path 38 and the pressure release path 42.

A hot water supply passage 46 for supplying hot water in the hot water storage tank 14 to the hot water tap 44 is connected to the ceiling portion of the hot water storage tank 14. The hot-water tap 44 is disposed in a bathroom, a washroom, a kitchen, or the like. In the hot water supply path 46, a pressure relief valve 48, a hot water solenoid valve 50, a high temperature thermistor 52, and a hot water supply thermistor 54 are interposed. The hot water supply path 46 is connected to the mixing path 36 described above. The mixing path 36 is downstream of the hot water solenoid valve 50 and is connected between the high temperature thermistor 52 and the hot water supply thermistor 54.
The pressure relief valve 48 is connected to the pressure release path 42. Hot water solenoid valve 50 is opened when hot water supply is started and closed when hot water supply is completed. Whether or not the hot water supply is started is determined by the controller 146 based on the detected flow rate of the water supply amount sensor 30 (detailed later). The high temperature thermistor 52 detects the temperature of the hot water sent out from the hot water storage tank 14. The hot water supply thermistor 54 detects the temperature of the mixed water of the hot water from the hot water supply path 46 and the tap water from the mixing path 36. Detection signals from the high temperature thermistor 52 and the hot water supply thermistor 54 are output to the controller 146. The mixing ratio of the hot water from the hot water supply path 46 and the tap water from the mixing path 36 is adjusted by the opening degree of the mixing servo 34. The hot water supply temperature can be adjusted by adjusting the opening of the mixing servo 34. The opening degree of the mixing servo 34 is instructed by the controller 146 based on the detected temperature of the water supply thermistor 28 and the detected temperature of the hot water supply thermistor 54.

The hot water storage tank 14 and the power generation unit 150 are connected by a heat recovery circulation path 56. The heat recovery circulation path 56 is disposed so as to pass through the heat recovery heat exchanger 154. In the heat recovery circulation path 56, a path from the hot water storage tank 14 to the heat recovery heat exchanger 154 is a heat recovery circulation forward path 56a, and a path from the heat recovery heat exchanger 154 to the hot water storage tank 14 is a heat recovery circulation return path 56b. It is.
The heat recovery circulation forward path 56 a connects the bottom of the hot water storage tank 14 and the upstream end of the heat recovery heat exchanger 154. A heat recovery circulation pump 58 and a circulation outward path thermistor 60 are interposed in the heat recovery circulation path 56a. The heat recovery circulation pump 58 circulates hot water in the heat recovery circulation path 56. The heat recovery circulation pump 58 is driven during the power generation operation or during the freeze prevention operation of the hot water in the heat recovery circulation path 56. The drive of the heat recovery circulation pump 58 is controlled by the controller 146. The circulation outward thermistor 60 is disposed in the vicinity of the hot water storage tank 14 and detects the temperature of the hot water delivered from the hot water storage tank 14. A detection signal from the circulation forward thermistor 60 is output to the controller 146.
The heat recovery circulation return path 56 b connects the downstream end of the heat recovery heat exchanger 154 and the ceiling of the hot water storage tank 14. A circulation return thermistor 62 and a three-way valve 64 are interposed in the heat recovery circulation return path 56b. The circulation return thermistor 62 is disposed upstream of the three-way valve 64 and detects the temperature of the hot water after passing through the heat recovery heat exchanger 154. A detection signal of the circulation return thermistor 62 is output to the controller 146. The three-way valve 64 has two inlets 64a and 64b and an outlet 64c. The upstream portion of the heat recovery circulation return path 56b is connected to the inlet 64a, and the downstream portion of the heat recovery circulation return path 56b is connected to the outlet 64c. One end of a bypass path 66 is connected to the inlet 64 b of the three-way valve 64. The other end of the bypass path 66 is connected in the middle of the heat recovery circulation forward path 56a. When the inlet 64a and the outlet 64c of the three-way valve 64 communicate with each other, a circulation path is formed via the power generation unit 150 and the hot water storage tank 14, and when the inlet 64b and the outlet 64c of the three-way valve 64 communicate with each other, the hot water storage via the power generation unit 150 is established. A circulation path that bypasses the tank 14 is formed. Switching of the three-way valve 64 is controlled by the controller 146.

The burner unit 68 includes a burner 70, a latent heat exchanger 72, and a sensible heat exchanger 74. The burner 70 burns using gas as fuel. The hot water in the latent heat exchanger 72 is preheated by the heat of the combustion exhaust gas generated in the burner 70. At this time, due to the temperature drop of the combustion exhaust gas, water vapor in the combustion exhaust gas is condensed, and acidic drain in which nitrogen oxides are dissolved is generated. The hot water preheated by the latent heat exchanger 72 is reheated by the combustion heat of the burner 70 by the sensible heat exchanger 74.
A drain path 92 for discharging or collecting the drain is connected to the latent heat exchanger 72. The drain path 92 is connected to the pressure release path 42. A neutralizer 94 is interposed in the drain path 92. The neutralizer 94 is filled with calcium carbonate. The acidic drain is neutralized to pH 6 to 7 by calcium carbonate while passing through the neutralizer 94. An overflow path 98 is connected to the drain path 92 on the downstream side of the neutralizer 94. The other end of the overflow path 98 is connected to the cistern 100, and when the hot water in the cistern 100 exceeds a predetermined water level, the hot water corresponding to the predetermined water level is discharged from the cistern 100.

The hot water storage tank 14 and the burner unit 68 are connected by a burner circulation path 76. The burner circulation path 76 is disposed so as to pass through the latent heat exchanger 72 and the sensible heat exchanger 74 in the burner section 68 in order. In the burner circulation path 76, the path from the hot water storage tank 14 to the burner section 68 is a burner circulation forward path 76a, and the path from the burner section 68 to the hot water storage tank 14 is a burner circulation return path 76b. A bypass path 78 that bypasses the burner portion 68 is formed in the burner circulation path 76. The upstream end of the bypass path 78 is connected to the burner circulation forward path 76a, and the downstream end of the bypass path 78 is connected to the burner circulation return path 76b.
The burner circulation forward path 76 a connects the intermediate portion of the hot water storage tank 14 (intermediate between the first tank thermistor 16 and the second tank thermistor 18) and the upstream end of the latent heat exchanger 72. A burner circulation pump 80, a burner circulation flow sensor 82, a burner circulation flow servo 84, and a burner bypass servo 86 are interposed in the burner circulation forward path 76a. The burner circulation pump 80 circulates hot water in the burner circulation path 76. The drive of the burner circulation pump 80 is controlled by the controller 146. The burner circulation flow sensor 82 detects the flow rate of hot water in the burner circulation path 76. The detection signal of the burner circulation flow sensor 82 is output to the controller 146. Each of the burner circulation flow servo 84 and the burner bypass servo 86 has a built-in stepping motor, which is driven to adjust the opening and change the flow rate. The burner circulation flow rate servo 84 adjusts the flow rate of hot water in the burner circulation path 76. The opening degree of the burner circulation flow servo 84 is controlled by the controller 146. The burner bypass servo 86 is disposed at a connection portion between the burner circulation forward path 76 a and the upstream end of the bypass path 78. Of the hot water in the burner circulation path 76, the flow rate of the hot water flowing toward the burner section 68 and the bypass path 78. Adjust the flow rate of hot water flowing to the side. By adjusting the opening degree of the burner bypass servo 86, the temperature of the hot water downstream of the connecting portion between the burner circulation return path 76b and the downstream end of the bypass path 78 can be adjusted. The opening degree of the burner bypass servo 86 is controlled by the controller 146.
The burner circulation return path 76 b connects the downstream end of the sensible heat exchanger 74 and the ceiling of the hot water storage tank 14. The burner circulation return path 76 b is disposed so as to pass through the heating heat exchanger 114. Heat of the hot water in the burner circulation return path 76b is input to the heating heat exchanger 114. A burner outlet thermistor 88 and a heat exchanger outlet thermistor 90 are interposed in the burner circulation return path 76b. The burner outlet thermistor 88 is disposed downstream of the connection portion between the burner circulation return path 76 b and the downstream end of the bypass path 78, and detects the temperature of the hot water after passing through the burner section 68 and / or the bypass path 78. . The heat exchanger outlet thermistor 90 is disposed downstream of the heating heat exchanger 114 and detects the temperature of the hot water after passing through the heating heat exchanger 114. The detection signal from the burner outlet thermistor 88 and the detection signal from the heat exchanger outlet thermistor 90 are output to the controller 146. A first control valve 160 is provided on the downstream side of the heat exchanger outlet thermistor 90 in the burner circulation return path 76b. Opening and closing of the first control valve 160 is controlled by the controller 146.

  One end of the second burner circulation return path 166 is connected between the heat exchanger outlet thermistor 90 and the first control valve 160 in the burner circulation return path 76b. The other end of the second burner circulation return path 166 is connected between the hot water storage tank 14 and the burner circulation pump 80 in the burner circulation forward path 76a. A second control valve 162 is provided in the second burner circulation return path 166. Opening and closing of the second control valve 162 is controlled by the controller 146.

  One end of a third burner circulation return path 168 is connected between the heat exchanger outlet thermistor 90 and the first control valve 160 in the burner circulation return path 76b. The other end of the third burner circulation return path 168 is connected to the lower part of the hot water storage tank 14. A third control valve 164 is provided in the third burner circulation return path 168. Opening and closing of the third control valve 164 is controlled by the controller 146.

  The first control valve 160, the second control valve 162, and the third control valve 164 are controlled by the controller 146 such that any one of them is opened and the other two are closed. When the first control valve 160 is opened and the second control valve 162 and the third control valve 164 are closed, the hot water that has passed through the heating heat exchanger 114 passes through the burner circulation return path 76b to the upper part of the hot water storage tank 14. Inflow. When the second control valve 162 is opened and the first control valve 160 and the third control valve 164 are closed, the hot water that has passed through the heating heat exchanger 114 passes through the second burner circulation return path 166 from the burner circulation return path 76b. Into the burner circulation forward passage 76a. When the third control valve 164 is opened and the first control valve 160 and the second control valve 162 are closed, the hot water that has passed through the heating heat exchanger 114 passes through the third burner circulation return path 166 from the burner circulation return path 76b. And flows into the lower part of the hot water storage tank 14.

  From the hot water supply path 46, a systern water supply path 102 branches off. A negative pressure valve 104 and a cistern water supply valve 106 are interposed in the cistern water supply path 102. The negative pressure valve 104 is opened when the water supply path 24 becomes negative pressure due to a water interruption or the like, and sucks the air to prevent the hot water storage tank 14 from being damaged due to the negative pressure. The cistern water supply valve 106 is opened when hot water from the hot water storage tank 14 is supplied to the cistern 100. The water level of the hot water in the cistern 100 is monitored by a water level sensor (not shown). When the water level of the hot water in the cistern 100 is within a predetermined water level range, the cistern water supply valve 106 is closed. When it is determined that the water level has deviated from the predetermined water level range, the cistern water supply valve 106 is opened. Opening and closing of the cistern water supply valve 106 is controlled by the controller 146.

  In this embodiment, the thermal load 108 includes a heating device, a bath device, and a hot water supply device. As a terminal of the heating device, it has an air conditioner and a floor heater. In FIG. 1, an air conditioner and a floor heater are shown as a heating terminal 110. The systern 100 and the heating terminal 110 are connected by a heating circulation path 112. In the heating circulation path 112, a path from the systern 100 to the heating terminal 110 is a heating circulation forward path 112a, and a path from the heating terminal 110 to the systern 100 is a heating circulation return path 112b. The heating circulation forward path 112 a is disposed so as to pass through the heating heat exchanger 114. A heating circulation pump 116 and a heating circulation thermistor 118 are interposed in the heating circulation forward path 112a. The heating circulation pump 116 circulates hot water in the heating circulation path 112. The heating circulation pump 116 is driven in accordance with the switch operation of the heating terminal 110. The driving of the heating circulation pump 116 is controlled by the controller 146. The heating circulation thermistor 118 is arranged downstream of the heating heat exchanger 114 and detects the temperature of the hot water after passing through the heating heat exchanger 114. A detection signal from the heating circulation thermistor 118 is output to the controller 146. A heating thermal valve 120 is interposed in the heating circulation path 112 in the heating terminal 110. The heating thermal valve 120 opens and closes according to the operation of the switch of the heating terminal. The controller 146 controls the opening / closing of the heating / thermal valve 120.

  On the downstream side of the heating circulation path 112a, the reheating path 122 branches off from the downstream side of the heating circulation thermistor 118. The downstream end of the tracking path 122 is connected to the vicinity of the cistern 100 of the heating circulation return path 112b. The chasing path 122 is arranged so as to pass through the bath heat exchanger 124. The heat of the hot water in the heating circulation forward path 112a is input to the bath heat exchanger 124. A tracking heat valve 126 is interposed in the tracking path 122. The reheating heat valve 126 opens and closes when the bath reheating switch is operated. Opening and closing of the reheating heat valve 126 is controlled by the controller 146.

  A bath circulation path 130 is connected to the bath tub 128. The bath circulation path 130 is disposed so as to pass through the bath heat exchanger 124. In the bath circulation path 130, a path from the bathtub 128 to the bath heat exchanger 124 is a bath circulation forward path 130a, and a path from the bath heat exchanger 124 to the bathtub 128 is a bath circulation return path 130b. A bath water level sensor 132, a bath circulation pump 134, a bath water flow switch 136, and a bath circulation thermistor 138 are interposed in the bath circulation outward path 130a. The bath water level sensor 132 detects the water pressure of the hot water in the bath circulation path 130. A detection signal of the bath water level sensor 132 is output to the controller 146. The water pressure detected by the bath water level sensor 132 is used to estimate the hot water level in the bathtub 128. The bath circulation pump 134 circulates hot water in the bath circulation path 130. The bath circulation pump 134 is driven in accordance with the operation of the switch of the remote controller 148. The driving of the bath circulation pump 134 is controlled by the controller 146. The bath water flow switch 136 is turned on when hot water flows in the bath circulation path 130. An on / off signal of the bath water flow switch 136 is output to the controller 146. The bath circulation thermistor 138 is arranged on the upstream side of the bath heat exchanger 124 and detects the temperature of warm water entering the bath heat exchanger 124. A detection signal from the bath circulation thermistor 138 is output to the controller 146.

  The hot water supply path 46 and the bath circulation path 130 are connected by a hot water supply path 140. The upstream end of the hot water supply route 140 is connected to the downstream side of the hot water supply thermistor 54 of the hot water supply route 46, and the downstream end of the hot water supply route 140 is a bath circulation pump 134 and a bath water flow switch of the bath circulation outward route 130 a of the bath circulation route 130. 136. A hot water filling amount sensor 142 and a pouring electromagnetic valve 144 are interposed in the hot water filling route 140. The hot water filling amount sensor 142 detects the flow rate of hot water passing through the hot water filling route 140. The detection signal of the hot water filling amount sensor 142 is output to the controller 146. The hot water solenoid valve 144 is opened and closed by operating the switch of the remote controller 148 or the level of hot water in the bathtub 128. Opening and closing of the pouring solenoid valve 144 is controlled by the controller 146.

  Next, the heat storage operation, hot water supply operation, heating operation, bath hot water operation, and bath renewal operation performed in the hot water supply unit 10 will be described.

(Heat storage operation)
Since the heat storage operation is performed in the same manner as a conventional cogeneration system, a detailed description is avoided and only a general description is given. When the power generation operation is performed in the power generation unit 150, the heat medium in the heat medium circulation path 152 circulates, and the generated heat is input to the heat recovery heat exchanger 154. In the hot water supply unit 10, the heat recovery circulation pump 58 is driven, and the hot water in the hot water storage tank 14 is sucked out from the bottom of the hot water storage tank 14 to the heat recovery circulation forward path 56a. The hot water in the heat recovery circulation path 56a flows into the heat recovery heat exchanger 154 and is heated. The heated hot water is returned to the ceiling portion of the hot water storage tank 14 through the heat recovery circulation return path 56b. As a result, the generated heat generated by the power generation in the power generation unit 150 is collected into the hot water storage tank 14 and stored. The hot water in the hot water storage tank 14 is heated from above.

  When the heat storage in the hot water storage tank 14 is completed and the full storage state is reached, the cistern water supply valve 106 is opened. As a result, the high-temperature water stored in the upper part of the hot water storage tank 14 is supplied into the cistern 100 through the cistern water supply path 102. The hot water in the cistern 100 is used when performing a heating operation or a bath rebirth operation described later.

(Hot water operation)
The hot water supply operation will be described with reference to FIGS. FIG. 2 shows an outline of the operation of the cogeneration system in the hot water supply operation. In the hot water supply operation, water or hot water circulates in the path indicated by a thick line in FIG. FIG. 3 is a flowchart of the hot water supply operation.

  In step S10 of FIG. 3, it is determined whether or not the detected flow rate of the water supply amount sensor 30 is 2.7 liters / min or more. When the detected flow rate of the water supply amount sensor 30 is 2.7 liters / min or more (YES in step S10), it is considered that the hot water tap 44 is opened and a hot water supply request is made. Proceeding to step S12, the hot water solenoid valve 50 is opened. As a result, the hot water stored in the upper part of the hot water storage tank 14 is sent out to the hot water supply path 46.

  In step S14, it is determined whether or not the detected temperature of the first tank thermistor 16 is 60 ° C. or higher. If the detected temperature of first tank thermistor 16 is 60 ° C. or higher (YES in step S14), it is considered that hot water in hot water storage tank 14 can be used for hot water supply without heating. In such a case, the process proceeds to step S16 and the non-combustion hot water supply operation is performed. In the non-combustion hot water supply operation, the burner 70 is not combusted, and the burner circulation pump 80 is not driven. In step S16, if the burner 70 is burning, the fire is extinguished, and if the burner circulation pump 80 is driven, it is stopped.

  If the detected temperature of the first tank thermistor 16 is less than 60 ° C. (NO in step S14), it is considered that the hot water in the hot water storage tank 14 cannot be used for hot water supply without heating. In such a case, the process proceeds to step S22, and the combustion hot water supply operation is performed. In the combustion hot water supply operation, the burner 70 is combusted and the burner circulation pump 80 is driven. In step S18, the burner 70 is ignited if not burning, and is driven if the burner circulation pump 80 is not driven. In step S20, the first control valve 160 is opened, and the second control valve 162 and the third control valve 164 are closed. As a result, the hot water in the intermediate portion of the hot water storage tank 14 is sent to the burner portion 68 through the burner circulation forward path 76a and heated. In step S22, the combustion amount of the burner 70 and the opening degree of the burner bypass servo 86 are controlled so that the detected temperature of the burner outlet thermistor 88 is 65 ° C. The hot water sent to the burner section 68 is heated to 65 ° C. and returned to the upper part of the hot water storage tank 14 through the burner circulation return path 76b.

In step S24, the opening degree of the mixing servo 34 is adjusted so that the detected temperature of the hot water supply thermistor 54 becomes the hot water supply set temperature. As a result, the hot water sent from the upper part of the hot water storage tank 14 to the hot water supply path 46 is adjusted to the hot water supply set temperature and supplied to the hot water tap 44.
In step S26, it is determined whether or not the detected flow rate of the water supply amount sensor 30 is 2.0 liters / min or less. If the detected flow rate of the water supply amount sensor 30 exceeds 2.0 liters / min (NO in step S26), the hot-water tap 44 is still open and it is considered that hot water is being supplied, and the process proceeds to step S14. Return. If the hot water temperature in the upper part of the hot water storage tank 14 is 60 ° C. or higher, the non-combustion hot water supply operation is performed. If the hot water temperature in the upper part of the hot water storage tank 14 is lower than 60 ° C., the combustion hot water supply operation is performed. By performing the combustion hot water supply operation, hot water heated to 65 ° C. by the burner 70 is stored above the first tank thermistor 16 of the hot water storage tank 14. Thereby, the upper part of the hot water storage tank 14 becomes a buffer tank in which hot water of 65 ° C. is stored. Hot water of 65 ° C. is sent out from the upper part of the hot water storage tank 14 formed into a buffer tank to the hot water supply path 46, adjusted to the hot water supply set temperature, and hot water is supplied. The temperature of the hot water supply temperature is adjusted by adjusting the opening degree of the mixing servo 34. From the detected temperature of the hot water supply thermistor 28 and the detected temperature of the hot water supply thermistor 54, the opening degree of the mixing servo 34 is adjusted so that the detected temperature of the hot water supply thermistor 28 becomes the hot water supply set temperature.
In step S26, if the detected flow rate of the water supply amount sensor 30 is 2.0 liters / min or less (if YES), it is considered that the hot water tap 44 is closed. Proceeding to step S28, the hot water solenoid valve 50 is closed and the hot water supply operation is terminated.

(Heating operation)
The heating operation will be described with reference to FIGS. 4 to 6 show an outline of the operation of the cogeneration system in the heating operation. In the heating operation, water or hot water flows through the path indicated by the solid line in FIGS. 4 to 6 in accordance with the switching of the hot water flow path. 7 and 8 are flowcharts of the heating operation.

  In step S40 in FIG. 7, it is determined whether or not a heating ON signal has been output by operating a switch on the remote controller of the heating device. If it is determined that the heating ON signal has been output (YES in step S40), it is considered that there has been an operation request for heating terminal 110. Below, the case where the activated heating apparatus is a floor heater which is a low-temperature terminal will be described. In step S42, the burner circulation pump 80 is driven. As a result, hot water is sent out to the burner unit 68. In addition, the heating thermal valve 120 of the heating terminal 110 is opened, and the heating circulation pump 116 is driven. Accordingly, the hot water in the systern 100 passes through the heating heat exchanger 114 and is sent to the heating terminal 110.

  In step S44, it is determined whether or not the detected temperature of the second tank thermistor 18 is 62 ° C. or higher. If the detected temperature of the second tank thermistor 18 is 62 ° C. or higher (YES in step S44), it is considered that the heating operation is possible only by the heat storage above the intermediate portion of the hot water storage tank. In such a case, it is not necessary to return the hot water sent out from the heating heat exchanger 114 to the upper part of the hot water storage tank 14, but return the hot water to the lower part of the hot water storage tank 14 or bypass the hot water storage tank 14 to burner circulation forward path 76a. Is selected in step S46 and thereafter. In step S46, it is determined whether or not the detected temperature of the fourth tank thermistor 22 is 40 ° C. or higher. When the detected temperature of the fourth tank thermistor 22 is 40 ° C. or higher (in the case of YES at step S46), the hot water storage tank 14 is fully stored and heat recovery from the power generation unit 150 to the hot water storage tank 14 is not performed. Therefore, there is no problem even if the hot water in the lower part of the hot water storage tank 14 becomes hot. Therefore, in such a case, the process proceeds to step S48, and the hot water from the burner circulation return path 76b flows into the lower part of the hot water storage tank 14. In step S48, if the burner 70 is burning at this time, the fire is extinguished. In step S50, the third control valve 164 is opened, and the first control valve 160 and the second control valve 162 are closed. As a result, as shown in FIG. 6, the hot water in the intermediate portion of the hot water storage tank 14 is sent to the burner portion 68 via the burner circulation forward path 76a, and is sent to the heating heat exchanger 114 without being heated. The hot water cooled by the heat exchange in the heating heat exchanger 114 is returned to the lower part of the hot water storage tank 14. On the other hand, the hot water sent out from the systern 100 is heated by heat exchange in the heating heat exchanger 114 and used for heating in the heating terminal 110. The hot water that has passed through the heating terminal 110 returns to the systern 100.

  If the detected temperature of the fourth tank thermistor 22 is less than 40 ° C. in step S46 of FIG. 7 (in the case of NO), the hot water storage tank 14 is not fully stored, and heat recovery from the power generation unit 150 to the hot water storage tank 14 is performed. There is a possibility that. Therefore, in such a case, it is necessary to prevent the hot water below the hot water storage tank 14 from becoming high temperature. In step S52, it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher. When the detected temperature of the heat exchanger outlet thermistor 90 is less than 38 ° C. (in the case of NO in step S52), the hot water sent from the heating heat exchanger 114 is sufficiently low in temperature, so the process proceeds to step S48. The hot water is returned to the lower part of the hot water storage tank 14. When the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher (in the case of YES in step S52), the hot water sent from the heating heat exchanger 114 is not sufficiently low, and the process proceeds to step S54. The warm water is allowed to flow into the burner circulation forward path 76a without returning to the hot water storage tank 14. In step S54, the second control valve 162 is opened, and the first control valve 160 and the third control valve 164 are closed. As a result, as shown in FIG. 5, the hot water is sent to the burner section 68 through the burner circulation forward path 76a, and is sent to the heating heat exchanger 114 without being heated. The hot water cooled by heat exchange in the heating heat exchanger 114 again flows into the burner circulation forward path 76a.

  If the detected temperature of the second tank thermistor 18 is lower than 62 ° C. in step S44 of FIG. 7 (if NO), it is determined that the heating operation cannot be performed only by the heat storage in the upper part of the hot water storage tank 14. In such a case, it progresses to step S62 of FIG. 8, and a combustion heating operation is performed. In step S62, it is determined whether or not the burner 70 has already been burned. If the burner 70 is not combusting (NO in step S62), the process proceeds to step S66 in order to determine whether the burner 70 needs to be ignited. In step S66, it is determined whether or not the temperature detected by the heating circulation thermistor 118 is below 48 ° C. When the temperature detected by the heating circulation thermistor 118 is lower than 48 ° C. (in the case of YES at step S66), the temperature of the hot water sent to the heating terminal 110 is low, so the process proceeds to step S68 and the burner 70 is ignited. In step S70, the combustion amount of the burner 70 and the opening degree of the burner bypass servo 86 are controlled so that the detected temperature of the burner outlet thermistor 88 becomes 65 ° C.

  In step S66, when the temperature detected by the heating circulation thermistor 118 is 48 ° C. or higher (NO in step S66), the hot water having the temperature required by the heating terminal 110 is not burned without burning the burner 70. Since it has been sent to the heating terminal 110, the process proceeds to step S72 without igniting the burner 70.

  If the burner 70 has already been burned in step S62 (YES in step S62), the process proceeds to step S64 in order to determine whether the burner 70 needs to be extinguished. In step S64, it is determined whether or not the temperature detected by the heating circulation thermistor 118 exceeds 72 ° C. When the temperature detected by the heating circulation thermistor 118 exceeds 72 ° C. (in the case of YES at step S64), the hot water sent to the heating terminal 110 is too hot, so the process proceeds to step S65, where the burner 70 Extinguish the fire.

  When the temperature detected by the heating circulation thermistor 118 in step S64 is 72 ° C. or lower (in the case of NO), the combustion of the burner 70 is maintained. In this case, the process proceeds to step S70, and the combustion amount of the burner 70 and the opening degree of the burner bypass servo 86 are controlled so that the detected temperature of the burner outlet thermistor 88 becomes 65 ° C.

  By the processes in steps S62 to S70, the ignition and extinguishing of the burner 70 are controlled so that the temperature of the hot water sent from the heating heat exchanger 114 to the heating terminal 110 falls within the range of 60 ° C. ± 12 ° C. If the detected temperature of the heating circulation thermistor 118 falls below 48 ° C. when the burner 70 is not burning, the burner 70 is ignited in step S68. If the detected temperature of the heating circulation thermistor 118 exceeds 72 ° C. while the burner 70 is burning, the burner 70 is extinguished in step S65. Thus, the ignition and extinguishing of the burner 70 are controlled so that the hot water sent to the heating terminal 110 is heated to the required temperature by the heating heat exchanger 114.

  In step S72, it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is 60 ° C. or higher. When the detected temperature of the heat exchanger outlet thermistor 90 is 60 ° C. or higher (in the case of YES in step S72), the hot water sent from the heating heat exchanger 114 is so high that there is no problem even if it is returned to the upper part of the hot water storage tank 14. It is. In such a case, the process proceeds to step S74, the first control valve 160 is opened, and the second control valve 162 and the third control valve 164 are closed. As a result, as shown in FIG. 4, the hot water sent out from the heating heat exchanger 114 is returned to the upper part of the hot water storage tank 14. In this case, the hot water in the intermediate part of the hot water storage tank 14 is sent to the burner part 68 via the burner circulation forward path 76a, heated as necessary, and sent to the heat exchanger 114 for heating. The hot water cooled by heat exchange in the heating heat exchanger 114 (note that the temperature after cooling is 60 ° C. or higher) is returned to the upper part of the hot water storage tank 14. On the other hand, the hot water sent out from the systern 100 is heated by heat exchange in the heating heat exchanger 114 and used for heating in the heating terminal 110. The hot water that has passed through the heating terminal 110 returns to the systern 100.

  If the detected temperature of the heat exchanger outlet thermistor 90 is less than 60 ° C. in step S 72 of FIG. 8 (in the case of NO), the hot water sent from the heating heat exchanger 114 is low in temperature to return to the upper part of the hot water storage tank 14. Therefore, the process proceeds to step S76. In step S76, it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher. If the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher (YES in step S76), the hot water sent from the heating heat exchanger 114 is hot enough to return to the lower part of the hot water storage tank 14, so step Proceeding to S80, the second control valve 162 is opened, and the first control valve 160 and the third control valve 164 are closed. As a result, the hot water sent out from the heating heat exchanger 114 bypasses the hot water storage tank 14 and flows into the burner circulation forward path 76a.

  In step S76, when the detected temperature of the heat exchanger outlet thermistor 90 is less than 38 ° C. (in the case of NO), there is no problem even if the hot water sent from the heating heat exchanger 114 is returned to the lower part of the hot water storage tank 14. It is very cold. In such a case, the process proceeds to step S78, and it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is lower than the detected temperature of the second tank thermistor 18. When the detected temperature of the heat exchanger outlet thermistor 90 is lower than the detected temperature of the second tank thermistor 18 (YES in step S78), the process proceeds to step S82, the third control valve 164 is opened, and the first control valve 160 and The second control valve 162 is closed. Thereby, the hot water sent out from the heating heat exchanger 114 is returned to the lower part of the hot water storage tank 14.

  When the detected temperature of the heat exchanger outlet thermistor 90 is equal to or higher than the detected temperature of the second tank thermistor 18 in step S78 (in the case of NO), the heating heat exchanger is determined from the temperature of the hot water sent from the hot water storage tank 14 to the burner unit 68. The temperature of the hot water delivered from 114 is higher. In such a case, the process proceeds to step S80, and the hot water sent from the heating heat exchanger 114 is allowed to flow into the burner circulation forward path 76a without returning to the hot water storage tank 14. Accordingly, hot water having a higher temperature can be supplied to the burner unit 68. The amount of combustion of the burner 70 required for heating operation can be suppressed, and the thermal efficiency can be improved.

  After step S74, step S80, or step S82, the process proceeds to step S56 in FIG. In step S56, it is determined whether or not a heating off signal has been output by operating the remote control switch of the heating device. Until the heating off signal is output, the processes in and after step S44 are repeated. When the heating off signal is output (YES in step S56), it is considered that there is a request to stop the operation of heating terminal 110. In this case, the process proceeds to step S58, and if the burner 70 is combusting at this time, the burner 70 is extinguished. Furthermore, it progresses to step S60, the burner circulation pump 80 is stopped, the heating thermal valve 120 is closed, the heating circulation pump 56 is stopped, and heating operation is complete | finished.

  In addition, although the case where the floor heater which is a low temperature terminal starts in the heating terminal 110 was demonstrated above, also when the air conditioner which is a high temperature terminal starts, heating operation can be performed by the same process. In this case, the temperature used as the determination criterion in step S44, step S64, step S66, and step S72 is changed to a temperature that matches the high temperature terminal. In step S70, the temperature used as the reference for control is changed to a temperature that matches the high temperature terminal.

(Bath bathing operation)
The bath chasing operation will be described with reference to FIGS. 9 to 11 show an outline of the operation of the cogeneration system in the chasing operation. In the chasing operation, water or hot water circulates in a path indicated by a solid line in FIGS. 9 to 11 in accordance with switching of the hot water flow path. 12 and 13 are flowcharts of the chasing operation.

  In step S90 of FIG. 12, it is determined whether or not the bath reheating switch of the remote controller 148 has been operated to output a reheating on signal. If it is determined that a tracking-on signal is output (YES in step S90), it is considered that there is a tracking request. In step S92, the burner circulation pump 80 is driven. As a result, hot water is sent out to the burner unit 68. In addition, the reheating heat valve 126 is opened, and the heating circulation pump 116 is driven. As a result, the hot water in the cistern 100 passes through the heating heat exchanger 114 and is sent to the bath heat exchanger 124. Further, the bath circulation pump 134 is driven. Thereby, the hot water in the bathtub 128 is sent out to the bath circulation outward path 130 a, passes through the bath heat exchanger 124, and returns to the bathtub 128.

  In step S94, it is determined whether or not the detected temperature of the second tank thermistor 18 is 82 ° C. or higher. If the detected temperature of the second tank thermistor 18 is 82 ° C. or higher (YES in step S94), it is considered that the reheating operation is possible only by the heat storage above the intermediate portion of the hot water storage tank. In such a case, it is not necessary to return the hot water sent out from the heating heat exchanger 114 to the upper part of the hot water storage tank 14, but return the hot water to the lower part of the hot water storage tank 14 or bypass the hot water storage tank 14 to burner circulation forward path 76a. Is selected in step S96 and thereafter. In step S96, it is determined whether or not the detected temperature of the fourth tank thermistor 22 is 40 ° C. or higher. When the detected temperature of the fourth tank thermistor 22 is 40 ° C. or higher (YES in step S96), the hot water storage tank 14 is fully stored, and heat recovery from the power generation unit 150 to the hot water storage tank 14 is not performed. Therefore, there is no problem even if the hot water in the lower part of the hot water storage tank 14 becomes hot. Therefore, in such a case, the process proceeds to step S98, and the hot water from the burner circulation return path 76b flows into the lower part of the hot water storage tank 14. In step S98, if the burner 70 is burning at this time, the fire is extinguished. In step S100, the third control valve 164 is opened, and the first control valve 160 and the second control valve 162 are closed. Accordingly, as shown in FIG. 11, the hot water in the intermediate portion of the hot water storage tank 14 is sent to the burner portion 68 via the burner circulation forward path 76a, and is sent to the heating heat exchanger 114 without being heated. The hot water cooled by the heat exchange in the heating heat exchanger 114 is returned to the lower part of the hot water storage tank 14. On the other hand, the hot water sent out from the systern 100 is heated by heat exchange in the heating heat exchanger 114 and sent out to the bath heat exchanger 124. The hot water cooled by the heat exchange in the bath heat exchanger 124 is returned to the cistern 100. Furthermore, the hot water sent out from the bathtub 128 is heated by heat exchange in the bath heat exchanger 124 and returns to the bathtub 128.

  If the detected temperature of the fourth tank thermistor 22 is lower than 40 ° C. in step S96 in FIG. 12 (in the case of NO), the hot water storage tank 14 is not fully stored, and heat recovery from the power generation unit 150 to the hot water storage tank 14 is performed. There is a possibility that. Therefore, in such a case, it is necessary to prevent the hot water below the hot water storage tank 14 from becoming high temperature. In step S102, it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher. When the detected temperature of the heat exchanger outlet thermistor 90 is less than 38 ° C. (in the case of NO in step S102), since the hot water sent out from the heating heat exchanger 114 is sufficiently low, the process proceeds to step S98. The hot water is returned to the lower part of the hot water storage tank 14. If the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher (in the case of YES in step S102), the hot water sent from the heating heat exchanger 114 is not sufficiently low, and the process proceeds to step S104. The warm water is allowed to flow into the burner circulation forward path 76a without returning to the hot water storage tank 14. In step S104, the second control valve 162 is opened, and the first control valve 160 and the third control valve 164 are closed. As a result, as shown in FIG. 10, the hot water is sent to the burner section 68 through the burner circulation forward path 76a, and is sent to the heating heat exchanger 114 without being heated. The hot water cooled by heat exchange in the heating heat exchanger 114 again flows into the burner circulation forward path 76a.

  If the detected temperature of the second tank thermistor 18 is less than 82 ° C. in step S94 in FIG. 12 (if NO), it is determined that the reheating operation cannot be performed only by the heat storage in the upper part of the hot water storage tank 14. In such a case, the process proceeds to step S112 in FIG. In step S112, it is determined whether or not the burner 70 has already been burned. If burner 70 is not combusting (NO in step S112), the process proceeds to step S118 in order to determine whether or not ignition of burner 70 is necessary. In step S118, it is determined whether or not the temperature detected by the heating circulation thermistor 118 is below 68 ° C. If the temperature detected by the heating circulation thermistor 118 is below 68 ° C. (in the case of YES in step S118), the temperature of the hot water sent to the bath heat exchanger 124 to heat the hot water in the bathtub 128 is low, and therefore, step Proceeding to S120, the burner 70 is ignited. In step S122, the combustion amount of the burner 70 and the opening degree of the burner bypass servo 86 are controlled so that the detected temperature of the burner outlet thermistor 88 is 85 ° C.

  If the temperature detected by the heating circulation thermistor 118 is 68 ° C. or higher in step S118 (NO in step S118), the temperature is sufficiently high to heat the hot water in the bathtub 128 without burning the burner 70. Since the hot water is sent to the bath heat exchanger 124, the process proceeds to step S124 without igniting the burner 70.

  If the burner 70 is already combusted in step S112 (YES in step S112), the process proceeds to step S114 in order to determine whether the burner 70 needs to be extinguished. In step S114, it is determined whether or not the temperature detected by the heating circulation thermistor 118 exceeds 87 ° C. When the temperature detected by the heating circulation thermistor 118 exceeds 87 ° C. (in the case of YES in step S114), the hot water sent to the bath heat exchanger 124 is too hot, and the process proceeds to step S116. Extinguish the burner 70.

  When the temperature detected by heating circulation thermistor 118 in step S114 is 87 ° C. or lower (in the case of NO), combustion of burner 70 is maintained. In this case, the process proceeds to step S122, and the combustion amount of the burner 70 and the opening degree of the burner bypass servo 86 are controlled so that the detected temperature of the burner outlet thermistor 88 becomes 85 ° C.

  By the processing of steps S112 to S122, the temperature of the hot water sent from the heating heat exchanger 114 to the bath heat exchanger 124 is within the range of 80 ° C-12 ° C = 68 ° C to 80 ° C + 7 ° C = 87 ° C. The ignition and extinguishing of the burner 70 are controlled. If the detected temperature of the heating circulation thermistor 118 falls below 68 ° C. when the burner 70 is not burning, the burner 70 is ignited in step S120. If the detected temperature of the heating circulation thermistor 118 exceeds 87 ° C. while the burner 70 is burning, the burner 70 is extinguished in step S116. Thus, the ignition and extinguishing of the burner 70 are controlled so that the hot water sent to the bath heat exchanger 124 is heated to the required temperature by the heating heat exchanger 114.

  In step S124, it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is 80 ° C. or higher. When the detected temperature of the heat exchanger outlet thermistor 90 is 80 ° C. or higher (in the case of YES in step S124), the hot water sent from the heating heat exchanger 114 is so high that there is no problem even if it is returned to the upper part of the hot water storage tank 14. It is. In such a case, the process proceeds to step S126, where the first control valve 160 is opened and the second control valve 162 and the third control valve 164 are closed. As a result, as shown in FIG. 9, the hot water sent out from the heating heat exchanger 114 is returned to the upper part of the hot water storage tank 14. In this case, the hot water in the intermediate part of the hot water storage tank 14 is sent to the burner part 68 via the burner circulation forward path 76a, heated as necessary, and sent to the heat exchanger 114 for heating. The hot water cooled by the heat exchange in the heating heat exchanger 114 (note that the temperature after cooling is 80 ° C. or higher) is returned to the upper part of the hot water storage tank 14. On the other hand, the hot water sent out from the systern 100 is heated by heat exchange in the heating heat exchanger 114 and sent out to the bath heat exchanger 124. The hot water cooled by the heat exchange in the bath heat exchanger 124 is returned to the cistern 100. Furthermore, the hot water sent out from the bathtub 128 is heated by heat exchange in the bath heat exchanger 124 and returns to the bathtub 128.

  When the detected temperature of the heat exchanger outlet thermistor 90 is less than 80 ° C. in step S124 of FIG. 13 (in the case of NO), the hot water sent from the heating heat exchanger 114 is low in temperature to return to the upper part of the hot water storage tank 14. Therefore, the process proceeds to step S128. In step S128, it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher. If the detected temperature of the heat exchanger outlet thermistor 90 is 38 ° C. or higher (YES in step S128), the hot water sent from the heating heat exchanger 114 is hot enough to return to the lower part of the hot water storage tank 14, so step Proceeding to S130, the second control valve 162 is opened, and the first control valve 160 and the third control valve 164 are closed. As a result, the hot water sent out from the heating heat exchanger 114 bypasses the hot water storage tank 14 and flows into the burner circulation forward path 76a.

  In step S128, when the detected temperature of the heat exchanger outlet thermistor 90 is less than 38 ° C. (in the case of NO), there is no problem even if the hot water sent from the heating heat exchanger 114 is returned to the lower part of the hot water storage tank 14. It is very cold. In such a case, the process proceeds to step S132, and it is determined whether or not the detected temperature of the heat exchanger outlet thermistor 90 is lower than the detected temperature of the second tank thermistor 18. When the detected temperature of the heat exchanger outlet thermistor 90 is lower than the detected temperature of the second tank thermistor 18 (YES in step S132), the process proceeds to step S134, the third control valve 164 is opened, and the first control valve 160 and The second control valve 162 is closed. Thereby, the hot water sent out from the heating heat exchanger 114 is returned to the lower part of the hot water storage tank 14.

  When the detected temperature of the heat exchanger outlet thermistor 90 is equal to or higher than the detected temperature of the second tank thermistor 18 in step S132 (in the case of NO), the heating heat exchanger is determined from the temperature of the hot water sent from the hot water storage tank 14 to the burner unit 68. The temperature of the hot water delivered from 114 is higher. In such a case, the process proceeds to step S130, and the hot water sent from the heating heat exchanger 114 is allowed to flow into the burner circulation forward path 76a without returning to the hot water storage tank 14. Accordingly, hot water having a higher temperature can be supplied to the burner unit 68. The amount of combustion of the burner 70 required for the chasing operation can be suppressed, and the thermal efficiency can be improved.

  After step S126, step S130, or step S134, the process proceeds to step S106 in FIG. In step S106, it is determined whether or not the detected temperature of the bath circulation thermistor 138 has reached the reheating set temperature. Until the detected temperature of the bath circulation thermistor 138 reaches the additional set temperature, the processing from step S94 onward is repeated. When the detected temperature of the bath circulation thermistor 138 reaches the additional set temperature (YES in step S106), it is considered that the temperature of the hot water in the bathtub 128 has reached the additional set temperature. In this case, the process proceeds to step S108, and if the burner 70 is combusting at this time, the burner 70 is extinguished. In step S110, the burner circulation pump 80 is stopped, the reheating heat valve 126 is closed, the heating circulation pump 56 is stopped, the bath circulation pump 134 is stopped, and the reheating operation of the bath is finished.

(Bath bathing operation)
The bath filling operation will be described with reference to FIGS. 14 and 15. FIG. 14 shows an outline of the operation of the cogeneration system in the hot water operation. In the hot water filling operation, water or hot water circulates in the path indicated by the solid line in FIG. FIG. 15 is a flowchart of the hot water operation.

  In step S140 of FIG. 15, it is determined whether the hot water filling switch of the remote controller 148 is operated and the hot water ON signal is output. If it is determined that the hot water on signal has been output (YES in step S140), it is considered that there has been a hot water request. In step S142, the hot water solenoid valve 144 is opened and the hot water solenoid valve 50 is opened. As a result, the hot water stored in the upper part of the hot water storage tank 14 is sent out to the hot water supply path 46 and supplied into the bathtub 128 through the hot water filling path 140 and the bath circulation path 130. In step S144, integration of the detected flow rate of the hot water filling amount sensor 142 is started.

  Proceeding to step S146, it is determined whether or not the detected temperature of the first tank thermistor 16 is 60 ° C. or higher. If the detected temperature of the first tank thermistor 16 is 60 ° C. or higher (YES in step S146), it is considered that the hot water in the hot water storage tank 14 can be used for hot water filling without heating. In such a case, it progresses to step S148 and a non-combustion hot water filling operation is performed. In the non-combustion hot water filling operation, the burner 70 is not burned and the burner circulation pump 80 is not driven. In step S148, if the burner 70 is burning, the fire is extinguished, and if the burner circulation pump 80 is driven, the burner 70 is stopped.

  If the detected temperature of the first tank thermistor 16 is less than 60 ° C. (NO in step S146), it is considered impossible to use the hot water in the hot water storage tank 14 for hot water filling without heating. In such a case, it progresses to step S150 and combustion hot water filling operation is performed. In the combustion hot water filling operation, the burner 70 is ignited and the burner circulation pump 80 is driven. In step S150, if the burner 70 is not burning, it is ignited, and if the burner circulation pump 80 is not driven, it is driven. In step S152, the first control valve 160 is opened, and the second control valve 162 and the third control valve 164 are closed. As a result, the hot water in the intermediate portion of the hot water storage tank 14 is sent to the burner portion 68 through the burner circulation forward path 76a and heated. In step S154, the combustion amount of the burner 70 and the opening degree of the burner bypass servo 86 are controlled so that the detected temperature of the burner outlet thermistor 88 becomes 65 ° C. The hot water sent to the burner section 68 is heated to 65 ° C. and returned to the upper part of the hot water storage tank 14 through the burner circulation return path 76b.

In step S156, the opening degree of the mixing servo 34 is adjusted so that the detected temperature of the hot water supply thermistor 54 becomes the hot water filling set temperature. Accordingly, the hot water sent from the upper part of the hot water storage tank 14 to the hot water supply path 46 is adjusted to the hot water filling set temperature and supplied to the bathtub 128.
In step S158, it is determined whether or not the integrated flow rate of the hot water filling amount sensor 142 is the hot water filling water amount. If the accumulated flow rate of the hot water filling amount sensor 142 does not satisfy the hot water filling set water amount (NO in step S158), the process returns to step S146. If the hot water temperature at the upper part of the hot water storage tank 14 is 60 ° C. or higher, the non-combustion hot water filling operation is performed, and if the hot water temperature at the upper part of the hot water storage tank 14 is lower than 60 ° C., the combustion hot water filling operation is performed. By performing the combustion hot water filling operation, the hot water heated to 65 ° C. by the burner 70 is stored above the first tank thermistor 16 of the hot water storage tank 14. Thereby, the upper part of the hot water storage tank 14 becomes a buffer tank in which hot water of 60 ° C. or more is stored. Hot water of 60 ° C. or more is sent out from the upper part of the hot water storage tank 14 formed into a buffer tank to the hot water supply passage 46, adjusted to a hot water filling set temperature, and hot water is supplied. The temperature of the hot water filling temperature is adjusted by adjusting the opening degree of the mixing servo 34. From the detected temperature of the hot water supply thermistor 28 and the detected temperature of the hot water supply thermistor 54, the opening degree of the mixing servo 34 is adjusted so that the detected temperature of the hot water supply thermistor 28 becomes the hot water filling set temperature.
If the integrated flow rate of the hot water filling amount sensor 142 becomes the hot water filling set water amount (YES) in step S158, it is considered that the hot water filling has been completed. Proceeding to step S160, the hot water solenoid valve 144 is closed, the hot water solenoid valve 50 is closed, and the hot water filling operation is terminated.

  In the present embodiment, since hot water is taken out from the intermediate portion of the hot water storage tank 14 and sent to the burner 70, the heat storage can be effectively used even when the amount of heat storage in the hot water storage tank 14 is small.

  In this embodiment, the hot water in the heating circulation path 112 is heated using the burner circulation path 76 for sending the hot water in the hot water storage tank 14 to the burner 70 and returning the hot water heated by the burner 70 to the hot water storage tank 14. can do. Further, the hot water in the bath circulation path 130 connected to the bathtub 128 can be heated using the bath retreat path 122 branched from the heating circulation path 112. Since one circulation path (burner circulation path 76) can be used in various ways, the system configuration can be simplified and the system can be made compact.

  In the present embodiment, the return destination of the hot water passing through the burner circulation return path 76 b can be switched according to the temperature detected by the heat exchanger outlet thermistor 90. Depending on the temperature detected by the heat exchanger outlet thermistor 90, the return destination of the hot water should be the upper part of the hot water storage tank 14, the lower part of the hot water storage tank 14, or the hot water storage tank 14 may be bypassed to become the burner circulation forward path 76a. Can do. By switching the return destination of the hot water in this way, the temperature stratification state formed in the hot water storage tank 14 is not destroyed.

Specific examples of the present invention have been described in detail above, 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.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

FIG. 1 is a system diagram of the cogeneration system of this embodiment. FIG. 2 is a diagram for explaining the flow of hot water during the hot water supply operation. FIG. 3 is a flowchart showing a hot water supply operation process. FIG. 4 is a diagram for explaining an aspect of the flow of hot water during the heating operation. FIG. 5 is a diagram for explaining another aspect of the flow of hot water during heating operation. FIG. 6 is a diagram for explaining still another aspect of the flow of hot water during the heating operation. FIG. 7 is a flowchart showing a heating operation process. FIG. 8 is a part of a flowchart showing a heating operation process. FIG. 9 is a diagram for explaining an aspect of the flow of hot water during the bath chasing operation. FIG. 10 is a diagram for explaining another aspect of the flow of hot water during the bath chasing operation. FIG. 11 is a view for explaining still another aspect of the flow of hot water during the bath chasing operation. FIG. 12 is a flowchart showing a process of bathing operation. FIG. 13 is a part of a flowchart showing a process of bathing operation. FIG. 14 is a diagram for explaining the flow of hot water during bath filling operation. FIG. 15 is a flowchart showing a bath filling operation process.

Explanation of symbols

10: Hot water supply unit 12: Hot water storage section 14: Hot water storage tank 16: First tank thermistor 18: Second tank thermistor 20: Third tank thermistor 22: Fourth tank thermistor 24: Water supply path 26: Pressure reducing valve 28: Water supply thermistor 30: Water supply amount sensor 32: Water supply amount servo 34: Mixing servo 36: Mixing route 38: Drainage route 40: Drainage valve 42: Pressure release route 44: Hot water tap 46: Hot water supply route 48: Pressure relief valve 50: Hot water solenoid valve 52: High temperature Thermistor 54: Hot water supply thermistor 56: Heat recovery circulation path, 56a: Circulation return path, 56b: Circulation return path 58: Heat recovery circulation pump 60: Circulation return path thermistor 62: Circulation return path thermistor 64: Three-way valve, 64a: Inlet, 64b: Inlet, 64c: outlet 66: bypass path 68: burner section 70: burner 72: latent heat exchanger 74: sensible heat exchanger 7 : Burner circulation path, 76a: Circulation return path, 76b: Circulation return path 78: Bypass path 80: Burner circulation pump 82: Burner circulation flow sensor 84: Burner circulation flow servo 86: Burner bypass servo 88: Burner outlet thermistor 90: Heat exchanger Outlet thermistor 92: Drain path 94: Neutralizer 98: Overflow path 100: Systurn 102: Systurn water supply path 104: Negative pressure valve 106: Systurn water supply valve 108: Thermal load 110: Heating terminal 112: Heating circulation path, 112a: Circulation Outward path 112b: Circulation return path 114: Heating heat exchanger 116: Heating circulation pump 118: Heating circulation thermistor 120: Heating circulation valve 122: Reheating path 124: Bath heat exchanger 126: Reheating heat valve 128: Bathtub 130: Bath circulation path, 130a: Circulation forward path, 130b: Circulation Return path 132: Bath water level sensor 134: Bath circulation pump 136: Bath water flow switch 138: Bath circulation thermistor 140: Hot water filling path 142: Hot water filling amount sensor 144: Pouring solenoid valve 146: Controller 148: Remote control 150: Power generation unit 152: Heat medium circulation path 154: heat recovery heat exchanger 160: first control valve 162: second control valve 164: third control valve

Claims (3)

Water is heated with the generated heat generated by the power generation unit, the heated hot water is stored, hot water is stored using the stored hot water, and the heat medium is heated using the stored hot water. A cogeneration system capable of
A hot water storage tank for storing hot water,
Power generation heat recovery means for sending hot water stored in the lower part of the hot water storage tank to the power generation unit and returning the hot water heated by the generated heat to the upper part of the hot water storage tank;
A heat source machine for heating hot water;
A hot water outbound route that sends hot water stored in a hot water storage tank to a heat source machine,
A first hot water return path for returning hot water heated by the heat source machine to the upper part of the hot water storage tank;
Hot water supply means for supplying hot water from the upper part of the hot water storage tank to the hot water use location,
A heat exchanger for exchanging heat between the hot water passing through the first hot water return path and the heat medium;
A temperature sensor for detecting the temperature of hot water passing through the first hot water return path downstream from the heat exchanger;
A second hot water return path that branches from the first hot water return path downstream of the temperature sensor and guides the hot water to the hot water forward path without passing through the hot water storage tank;
A third hot water return path that branches from the first hot water return path downstream of the temperature sensor and guides the hot water to the lower part of the hot water storage tank;
A first flow path that flows into the upper part of the hot water storage tank via the first hot water return path and a second flow path that flows into the warm water forward path via the second hot water return path are connected to the hot water flow path via the heat exchanger. A switching means for switching to one of the flow path and the third flow path flowing into the lower part of the hot water storage tank via the third hot water return path,
The switching means switches to the first flow path when the temperature detected by the temperature sensor is higher than the first predetermined temperature, and when the temperature detected by the temperature sensor is lower than the first predetermined temperature and higher than the second predetermined temperature. The cogeneration system is switched to the second flow path and switched to the third flow path when the temperature detected by the temperature sensor is lower than the second predetermined temperature.   The cogeneration system according to claim 1, wherein the heat medium circulates between the heating terminal and the heat exchanger. It is further equipped with a reheating heat exchanger that exchanges heat between hot water sent from the bath tub and the heat medium,
The cogeneration system according to claim 1 or 2, wherein the heat medium circulates between a heat exchanger and a reheating heat exchanger.

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