JP2018076998A - Cogeneration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freeze of a flow passage connected to a hot water tank, in a cogeneration system.SOLUTION: A control device 15 of a cogeneration system comprises a first freeze prevention control part (step S106) which drives a valve body 52, locates a position of the valve body 52 in a mixture position, drives a circulation pump 22a, and performs first freeze prevention control for circulating hot water to a hot water circulation path 22 when at least one of a first detection temperature detected by a first temperature sensor 22c being a temperature of the hot water flowing in the hot water circulation path 22 for circulating the hot water in a hot water storage tank 21, a second detection temperature detected by a second temperature sensor 23 being a temperature of water supplied to the hot water storage tank 21 via a water feed path 23, and a third detection temperature detected by a third temperature sensor 24d1 being a temperature of mixed hot water derived from a mixing valve 50 for mixing the hot water from the hot water storage tank 21 and the water from the water feed path 23 reaches a first prescribed temperature or lower.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cogeneration system.

  As one type of cogeneration system, one disclosed in Patent Document 1 is known. The cogeneration system (power generation system) of Patent Document 1 includes a power generation unit 1, an exhaust heat recovery unit including a hot water storage tank 2 that stores exhaust heat from the power generation unit 1, and water supply that supplies water to the hot water storage tank 2 from a water supply source. The circuit breaker 8 provided in the channel 11 and the water supply channel 11 that manually shuts off the communication between the water supply source and the hot water storage tank 2, and when the water temperature of the exhaust heat recovery unit decreases when the service life is stopped, the freezing of the exhaust heat recovery unit And a controller 20 that executes the preventive operation. The exhaust heat recovery unit includes a first circulation path 5 through which hot water in the hot water storage tank 2 circulates and a first pump 3 provided in the first circulation path 5.

  The freeze prevention operation is an operation in which the hot water in the hot water storage tank 2 is circulated through the first circulation path 5 by the operation of the first pump 3. As a result, the temperature of the exhaust heat recovery unit rises, thereby suppressing freezing of the exhaust heat recovery unit.

JP 2015-1111013 A

  However, freezing of hot water in the exhaust heat recovery unit occurs not only when the life of the cogeneration system stops, but also when the cogeneration system is not generating power (for example, when the cogeneration system is in a standby state). It is possible to do. The freezing of water occurs not only in the exhaust heat recovery unit, but also in the flow path between the hot water storage device (for example, a shower) using hot water stored in the hot water storage tank (hot water storage tank) and the hot water storage tank. It is possible.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to suppress freezing of a flow path connected to a hot water tank in a cogeneration system.

  In order to solve the above problems, a cogeneration system according to claim 1 is provided in a power generator, a hot water storage tank for storing hot water, a hot water circulation path for circulating hot water stored in the hot water storage tank, and a hot water circulation path. A circulating pump for circulating hot water, a heat exchanger provided in the hot water circulation path for exchanging heat from the power generator and hot water stored in the hot water storage tank, and water from the water source in the hot water storage tank It is connected to the water supply path to be supplied, the hot water supply path from which the hot water in the hot water tank is led out, and the water supply path, respectively, and the valve body is driven to change the position of the valve body from the hot water and the water supply path from the hot water supply path. The mixing position where water is mixed is generated to produce mixed hot water mixed with hot water and water, and the mixing valve for deriving the mixed hot water and the mixed hot water derived from the mixing valve are led to the hot water supply device Mixed hot water outlet and hot water circulation A first temperature sensor for detecting the temperature of the hot water, a second temperature sensor for detecting the temperature of the water provided in the water supply passage, and a first temperature sensor for detecting the temperature of the mixed hot water provided in the mixed hot water outlet passage. A cogeneration system comprising three temperature sensors and a control device that controls at least the power generation device, wherein the control device uses a first detected temperature and a second temperature sensor that are temperatures detected by the first temperature sensor. When at least one of the second detected temperature, which is the detected temperature, and the third detected temperature, which is the temperature detected by the third temperature sensor, falls below the first predetermined temperature, the valve body is driven. A first anti-freezing control unit is provided that executes the first anti-freezing control for positioning the valve body at the mixing position and driving the circulation pump to circulate hot and cold water.

  According to this, the hot water stored in the hot water tank circulates in the hot water circulation path by the first freeze prevention control, and the hot water in the hot water tank is led to the hot water outlet path, and passes through the mixing valve and the water supply path. Circulate back to the tank. Therefore, not only the hot water circulation path through which hot water in the hot water tank circulates, but also hot water in the hot water outlet path, the mixing valve and mixed hot water outlet path between the hot water tank and the hot water supply device, and the hot water path between the hot water tank and the water source. Temperature rises. Therefore, freezing of the flow path connected to the hot water tank can be suppressed.

It is the schematic which shows the outline | summary of one Embodiment of the cogeneration system by this invention. It is an axial sectional view of the mixing valve shown in FIG. The state where the position of the valve body is the mixing position is shown. It is a flowchart performed by the control apparatus shown in FIG.

  Hereinafter, an embodiment of a cogeneration system according to the present invention will be described. The cogeneration system of this embodiment is a fuel cell system. The fuel cell system 1 includes a power generation unit 10 and a hot water tank 21 as shown in FIG. The power generation unit 10 includes a housing 10a, a fuel cell module 11 (30), a heat exchanger 12, a power conversion device 13, a water tank 14, and a control device 15.

  The fuel cell module 30 (corresponding to the power generator of the present invention) includes a casing 31, an evaporation unit 32, a reforming unit 33, and a fuel cell 34. The casing 31 is formed in a box shape with a heat insulating material.

  In the fuel cell module 30, the other end of a reforming material supply pipe 11a to which one end is connected to a supply source Gs and a reforming material is supplied is connected to the evaporation section 32. The supply source Gs is, for example, a gas supply pipe for city gas or a gas cylinder for LP gas. The reforming material supply pipe 11a is provided with a material pump 11a1. The raw material pump 11a1 is a pump that sends the raw material for reforming.

  Further, one end (lower end) of the evaporating unit 32 is connected to the water tank 14 and the other end of the reforming water supply pipe 11b to which the reforming water is supplied. The reforming water supply pipe 11b is provided with a reforming water pump 11b1 for sending reforming water.

  The fuel cell module 30 has one end connected to the cathode air blower 11c1 and the other end of the cathode air supply pipe 11c into which the cathode air (air) as the oxidant gas is supplied into the casing 31. The cathode air blower 11c1 is a pump that sends cathode air.

  The evaporation unit 32 generates water vapor from the reformed water. Specifically, the evaporating unit 32 is heated by a combustion gas described later, and evaporates the reformed water supplied from the water tank 14 to generate water vapor. Further, the evaporation unit 32 preheats the reforming material supplied from the supply source Gs. The evaporation unit 32 mixes the steam generated in this way with the preheated reforming raw material and supplies the mixture to the reforming unit 33. The reforming raw materials include gas fuels for reforming such as natural gas and LP gas, and liquid fuels for reforming such as kerosene, gasoline, and methanol. In this embodiment, natural gas will be described.

  The reforming unit 33 generates reformed gas from the reforming raw material from the supply source Gs and the water vapor from the evaporation unit 32 and supplies the reformed gas to the fuel cell 34. Specifically, the reforming unit 33 is heated by a combustion gas, which will be described later, and supplied with heat necessary for the steam reforming reaction, so that the mixed gas (reforming raw material, water vapor) supplied from the evaporation unit 32 is supplied. ) To generate and derive the reformed gas.

  The reforming section 33 is filled with a catalyst (for example, Ru or Ni-based catalyst), and the reformed gas containing hydrogen gas and carbon monoxide is reformed by the reaction of the mixed gas by the catalyst. (So-called steam reforming reaction). The reformed gas contains hydrogen, carbon monoxide, carbon dioxide, steam, unreformed natural gas (methane gas), and reformed water (steam) that has not been used for reforming. The steam reforming reaction is an endothermic reaction.

  The fuel cell 34 generates power using fuel and oxidant gas. The fuel is a reformed gas. The fuel cell 34 is configured by laminating a fuel electrode, an air electrode (oxidant electrode), and a plurality of cells 34a made of an electrolyte interposed between the two electrodes. The fuel cell 34 of the present embodiment is a solid oxide fuel cell, and uses zirconium oxide, which is a kind of solid oxide, as an electrolyte.

  A reformed gas (hydrogen, carbon monoxide, methane gas, etc.) is supplied to the fuel electrode of the fuel cell 34 as fuel. A fuel channel 34b through which fuel (reformed gas) flows is formed on the fuel electrode side of the cell 34a. An air flow path 34c through which air (cathode air) that is an oxidant gas flows is formed on the air electrode side of the cell 34a. The fuel cell 34 generates power at a relatively high operating temperature (approximately 750 ° C. to 1000 ° C.).

  The fuel cell 34 is provided on the manifold 35. The reformed gas from the reforming unit 33 is supplied to the manifold 35 via the reformed gas supply pipe 38. The lower end (one end) of the fuel flow path 34b is connected to a fuel outlet (not shown) of the manifold 35 so that the reformed gas led out from the fuel outlet is introduced from the lower end and led out from the upper end. It has become.

  The cathode air sent out by the cathode air blower 11c1 is supplied via the cathode air supply pipe 11c, introduced from the lower end of the air flow path 34c, and led out from the upper end.

  A combustion unit 36 is provided between the fuel cell 34, the evaporation unit 32, and the reforming unit 33. In the combustion section 36, the anode off-gas (fuel off-gas) from the fuel cell 34 and the cathode off-gas (oxidant off-gas) from the fuel cell 34 are burned to generate combustion gas (flame 37). The combustion gas heats the evaporation unit 32 and the reforming unit 33. The combustion unit 36 is provided with a pair of ignition heaters 36a1 and 36a2 for igniting the anode off gas.

  In the combustion section 36, the anode off-gas is combusted to generate a relatively high-temperature combustion exhaust gas. The relatively high-temperature combustion exhaust gas is led to the heat exchanger 12. That is, the heat exchanger 12 is supplied with exhaust heat from the fuel cell module 30 by combustion exhaust gas. Further, the combustion unit 36 sets the temperature in the fuel cell module 30 to the operating temperature of the fuel cell 34.

  As described above, the fuel cell module 30 includes the fuel cell 34 that generates power using the fuel and the oxidant gas, the evaporation unit 32 that generates water vapor from the reformed water, and the reforming raw material and the evaporation unit 32 from the supply source Gs. And a reforming unit 33 that generates fuel from the water vapor and supplies the fuel cell 34 with the fuel.

  The hot water tank 21 stores hot water. The hot water storage tank 21 is provided with a hot water circulation path 22 which is a pipe through which hot water stored in the hot water storage tank 21 circulates (circulates in the direction of the arrow in the figure). On the hot water circulation path 22, the circulation pump 22a, the heating device 22b, the heat exchanger 12, and the first temperature sensor 22c are arranged in order from the lower end to the upper end of the hot water tank 21. An exhaust heat recovery system 20 is configured by the hot water storage tank 21, the hot water circulation path 22, the circulation pump 22a, the heating device 22b, the heat exchanger 12, and the first temperature sensor 22c. The exhaust heat recovery system 20 recovers and stores the exhaust heat of the fuel cell module 30 in hot water.

  The circulation pump 22a is a pump that is provided in the hot water circulation path 22 and circulates hot water. Circulation pump 22a adjusts the flow rate (flow rate per unit time) of sending hot and cold water according to the control command value transmitted from control device 15. Since the circulation pump 22a is PWM (Pulse Width Modulation) control, the control command value output to the circulation pump 22a is calculated by the duty ratio of PWM control.

  The heating device 22b is provided in the hot water circulation path 22 and heats hot water when electric power is supplied. The heating device 22b is a heater that generates heat when electric power is supplied. The electric resistance value of the heating device 22b is set to a predetermined electric resistance value (for example, 120Ω).

  The heat exchanger 12 is provided in the hot water circulation path 22 and performs heat exchange between the exhaust heat from the fuel cell module 30 and the hot water stored in the hot water storage tank 21. The heat exchanger 12 heats the hot water from the hot water storage tank 21 using the combustion exhaust gas including the exhaust heat from the fuel cell module 30.

  The heat exchanger 12 is connected (through) the exhaust pipe 11d from the fuel cell module 30. One end of a condensed water supply pipe 12 a is connected to the heat exchanger 12. In the heat exchanger 12, the combustion exhaust gas from the fuel cell module 30 is introduced into the heat exchanger 12 through the exhaust pipe 11 d, and heat is exchanged with the hot water supplied from the hot water tank 21 to be cooled. At the same time, water vapor in the combustion exhaust gas is condensed. The cooled combustion exhaust gas is discharged to the outside through the exhaust pipe 11d. Moreover, the condensed condensed water is supplied to the water tank 14 through the condensed water supply pipe 12a. The water tank 14 purifies the condensed water with an ion exchange resin and stores it as reformed water.

  The first temperature sensor 22c is provided in the hot water circulation path 22 and detects the temperature of the hot water. The 1st temperature sensor 22c detects the temperature of the hot water of the arrange | positioned position. The first detected temperature, which is the temperature detected by the first temperature sensor 22c, is transmitted to the control device 15.

  The hot water storage tank 21 is provided with a water supply channel 23 and a hot water supply device 24. The water supply channel 23 is a pipe that supplies water from the water source W to the hot water storage tank 21. One end of the water supply channel 23 is connected to the water source W, and the other end is connected to the hot water storage tank 21. The water source W is a water supply, for example. A second temperature sensor 23 a is disposed in the water supply path 23.

  The second temperature sensor 23 a is provided in the water supply channel 23 and detects the temperature of the water supplied to the hot water tank 21. The 2nd temperature sensor 23a detects the temperature of the water of the arrange | positioned position. The second detected temperature that is the temperature detected by the second temperature sensor 23 a is transmitted to the control device 15.

  The hot water supply device 24 supplies hot water stored in the hot water storage tank 21 to the hot water supply device 40. The hot water supply device 40 uses hot water in the hot water storage tank 21 as hot water supply. The hot water supply device 40 is, for example, a bathtub, a shower, or a kitchen (kitchen faucet). When the hot water supply of the hot water supply device 40 is started, a hot water supply start signal indicating that the hot water supply is started is transmitted to the control device 15. In addition, when the hot water supply of the hot water supply device 40 is stopped, a hot water supply stop signal indicating that the hot water supply is stopped is transmitted to the control device 15. The hot water supply device 24 includes a hot water outlet path 24a, a feed water branch path 24b, a mixing valve 24c (50), and a mixed hot water outlet path 24d.

  The hot water outlet path 24a is a pipe through which hot water from the hot water storage tank 21 is led out. One end of the hot water outlet passage 24a is connected to the hot water storage tank 21, and the other end is connected to the mixing valve 24c. The water supply branching path 24 b is branched from the water supply path 23. The water supply branch path 24b is a pipe that has one end connected to the water supply path 23 and supplies water from the water source W to the mixing valve 24c connected to the other end.

  The mixing valve 50 is connected to a hot water outlet passage 24 a and hot water supply passage 23 through which hot water from the hot water storage tank 21 is led. The mixing valve 50 is connected to the water supply passage 23 via a water supply branch passage 24b. The mixing valve 50 is driven by a valve body 52 to be described later, so that the position of the valve body 52 is set to a mixing position (described later) for mixing hot water from the hot water outlet passage 24a and water from the water supply passage 23. In this way, mixed hot water in which hot water and water are mixed is generated and mixed hot water is derived. As shown in FIG. 2, the mixing valve 50 includes a housing 51, a valve body 52, and a motor 53.

  The housing 51 is formed in a cylindrical shape, and accommodates the valve body 52 so as to be rotatable around an axis. The housing 51 is connected to the hot water outlet passage 24a, is connected to the first port 51a for introducing hot water from the hot water storage tank 21 and the water supply branch passage 24b, and is second to introduce water from the water supply branch passage 24b. A port 51b and a third port 51c for leading the mixed hot water are formed.

  The valve body 52 is formed in a cylindrical shape. The valve body 52 has a first opening 52a, a second opening 52b, and a third opening 52c. The 1st opening part 52a is formed in the surrounding side wall of the valve body 52, and introduces the hot water from the 1st port 51a inside. The 2nd opening part 52b is formed in the surrounding side wall of the valve body 52, and introduce | transduces the water from the 2nd port 51b inside. The third opening 52c is formed on the bottom wall of the valve body 52 so as to be always connected to the third port 51c.

  In addition, the valve body 52 is driven to rotate between a hot water fully closed position and a hot water fully open position. The hot water fully closed position is a position where the amount of hot water introduced into the valve body 52 from the hot water outlet path 24a becomes zero. The hot water fully open position is a position where the ratio of hot water and water becomes a predetermined ratio inside the valve body 52. As the valve body 52 rotates from the hot water fully closed position toward the hot water fully open position, the ratio of the amount of hot water gradually increases.

  A position other than the hot water fully closed position in the range in which the valve body 52 can rotate corresponds to a mixing position where hot water from the hot water outlet path 24 a and water from the water supply path 23 are mixed. In addition, the position of the valve body 52 shown in FIG. 2 is located in the mixing position. When the position of the valve body 52 is the mixing position, the first opening 52a and the second opening 52b communicate with each other, and thus the first port 51a, the second port 51b, and the third port 51c communicate with each other.

  The motor 53 drives the valve body 52 to rotate. The motor 53 is, for example, a stepping motor.

  When hot water supply by the hot water supply device 40 is not performed, the position of the valve body 52 is positioned at the hot water fully closed position by a control command from the control device 15. When hot water supply is performed by the hot water supply device 40, the position of the valve body 52 is positioned at the mixing position by a control command from the control device 15. Thereby, the hot water from the 1st opening part 52a and the water from the 2nd opening part 52b are mixed inside the valve body 52, and mixed hot water is produced | generated.

  Further, the valve body 52 is driven to rotate about the axis with respect to the housing 51, and the ratio of the hot water to the water is adjusted by changing the opening area of the hot water channel and the opening area of the water channel. The The produced mixed hot water is led out from the third opening 52c to the third port 51c. When the mixed hot water is derived, the position of the valve body 52 is controlled so that a third detected temperature detected by a third temperature sensor 24d1 described later becomes a hot water supply temperature (for example, 40 ° C.).

  As shown in FIG. 1, the mixed hot water outlet passage 24 d is a pipe that guides (supplies) the mixed hot water led out from the mixing valve 50 to the hot water supply device 40. One end of the mixed hot water outlet passage 24 d is connected to the third port 51 c of the mixing valve 50, and the other end is connected to the hot water supply device 40. When hot water is supplied by the hot water supply device 40, the mixed hot water derivation path 24 d leads the mixed hot water to the hot water supply device 40. A third temperature sensor 24d1 is provided in the mixed hot water outlet passage 24d.

  The third temperature sensor 24d1 is provided in the mixed hot water lead-out path 24d and detects the temperature of the mixed hot water. Specifically, the third temperature sensor 24d1 is provided on the hot water supply device 40 side from a connecting portion with a bypass passage 25 described later in the mixed hot water outlet passage 24d. The third temperature sensor 24d1 detects the temperature of the mixed hot water at the arranged position. The third detected temperature, which is the temperature detected by the third temperature sensor 24d1, is transmitted to the control device 15.

  The hot water supply device 24 is further provided with a bypass 25 and a bypass valve 25a. The bypass passage 25 is a pipe that bypasses the mixing valve 50 by connecting the water supply passage 23 and the mixed hot water outlet passage 24d and supplies water from the water source W to the mixed hot water outlet passage 24d.

  The bypass valve 25 a is an electromagnetic valve that is provided in the bypass passage 25 and has an open state that allows the water flow in the bypass passage 25 and a closed state that restricts the water flow in the bypass passage 25. The bypass valve 25a is a normally open solenoid valve that is closed when energized and opened when de-energized.

  When hot water is supplied by the hot water supply device 40, the third detected temperature detected by the third temperature sensor 24d1 is equal to or higher than the determination temperature (for example, 45 ° C.) because the temperature of the mixed hot water is relatively high. In this case, the bypass valve 25a is brought into a non-energized state by the control device 15, so that the bypass valve 25a is opened. Thereby, since the water from the water source W is supplied from the bypass path 25 to the mixed hot water outlet path 24d through which the mixed hot water flows, the temperature of the mixed hot water decreases. On the other hand, when the third detected temperature of the third temperature sensor 24d1 is lower than the determination temperature, the bypass valve 25a is controlled to be closed.

  The power converter 13 inputs the DC voltage output from the fuel cell 34 via the first power supply line 13a. The power converter 13 converts the DC voltage from the fuel cell 34 into a predetermined AC voltage, and is connected to an AC system power supply 16a and an external power load 16b (for example, an electrical appliance). To 13b.

  The power conversion device 13 receives the AC voltage from the system power supply 16a via the second power supply line 13b, converts it to a predetermined DC voltage, and outputs it to each auxiliary device and the control device 15. Each auxiliary machine includes a bypass valve 25a, a mixing valve 50, a raw material pump 11a1, a reforming water pump 11b1, a cathode air blower 11c1, and the like.

The power generation unit 10 further includes an outside air temperature sensor 60 and a power switching device 70.
The outside air temperature sensor 60 detects the temperature of outside air (hereinafter referred to as outside air temperature). The outside air temperature is a temperature outside the housing 10a. The outside air temperature sensor 60 is disposed at a position having a relative relationship with the outside air temperature in the housing 10a. That is, the outside air temperature sensor 60 indirectly detects the outside air temperature. The outside air detected temperature that is the outside air temperature detected by the outside air temperature sensor 60 is transmitted to the control device 15.

  The power switching device 70 is electrically connected to each of the fuel cell module 30, the system power supply 16a, and the heating device 22b, and switches between the power generated by the fuel cell module 30 and the power supplied from the system power supply 16a for heating. It supplies to the apparatus 22b.

  The power switching device 70 is electrically connected to the fuel cell module 30 and thus the fuel cell 34 via the first power supply line 13a and the third power supply line 13a1 branched from the first power supply line 13a. The power switching device 70 is electrically connected to the system power supply 16a via the second power supply line 13b and the fourth power supply line 13b1 branched from the second power supply line 13b. The second power supply line 13b and the fourth power supply line 13b1 are configured by a single-phase three-wire system. That is, the second power line 13b and the fourth power line 13b1 are configured by a first voltage line (not shown), a second voltage line (not shown), and a neutral line (not shown). The power switching device 70 is connected to the heating device 22b via the fifth power supply line 70a.

  When the power switching device 70 supplies the power from the system power supply 16a to the heating device 22b, the power supplied from the system power supply 16a is smaller than the first voltage value output from the fuel cell 34 in the autonomous power generation operation described later. It is provided so that it can be switched to one of a second voltage value (for example, 200V) and a third voltage value (for example, 100V) smaller than the second voltage value.

  When the power switching device 70 outputs the power supplied from the system power supply 16a as the second voltage value, the first voltage line, the second voltage line, and the neutral line of the fourth power supply line 13b1 The first voltage line and the second voltage line are connected to the fifth power supply line 70a. On the other hand, the power switching device 70 connects the neutral line, the first voltage line, and the fifth power supply line 70a when outputting the power supplied from the system power supply 16a at the third voltage value.

  The power switching device 70 is in a DC-on state in which a DC voltage from the fuel cell 34 is output to the heating device 22b, an AC-on state in which an AC voltage from the system power supply 16a is output to the heating device 22b, and a direct current from the fuel cell 34. The voltage and the AC voltage from the system power supply 16a are switched to either the off state (the AC on state or the DC on state) that is not output to the heating device 22b. The power switching device 70 is switched to the direct current on state when the fuel cell system 1 is in a self-sustaining power generation operation described later. In addition, the power switching device 70 is switched to the AC on state in the second freeze prevention control described later.

  The control device 15 controls the operation of the fuel cell system 1 by driving an auxiliary machine. The control device 15 controls at least the fuel cell module 30. The control device 15 includes a CPU unit (not shown) that executes arithmetic processing and a storage unit (not shown) such as a ROM. Further, the control device 15 includes a mixed hot water non-derivation time measuring unit (not shown). Based on the hot water supply start signal and the hot water supply stop signal from the hot water supply device 40, the mixed hot water non-derivation time measuring unit measures the time during which the mixed hot water is not derived (hereinafter referred to as mixed hot water non-derivation time). is there.

  Next, an example of a basic operation when power is transmitted from the system power supply 16a of the fuel cell system 1 described above will be described. When the start switch (not shown) is pressed and the operation is started, or when the operation is started according to the planned operation, the control device 15 starts the startup operation.

  When the start-up operation is started, the control device 15 operates the auxiliary machine. Specifically, the control device 15 operates the pumps 11a1 and 11b1 and starts supplying the raw material for reforming and the reforming water to the evaporation unit 32. As described above, a mixed gas is generated in the evaporation unit 32. In the reforming unit 33, the reformed gas is generated from the mixed gas, and the reformed gas is supplied to the fuel cell 34. Then, the anode off gas led out from the fuel cell 34 is ignited by the ignition heaters 36a1 and 36a2, and the combustion section 36 is ignited. When the reforming unit 33 reaches an operating temperature (for example, 400 ° C.) or higher, the start-up operation is finished and the power generation operation is started.

  During the power generation operation, the control device 15 controls the auxiliary machine so that the power generated by the fuel cell 34 is the power consumption of the external power load 16b (load following operation). When the power consumption of the external power load 16b exceeds the power generated by the fuel cell 34, the insufficient power is compensated by receiving power from the system power supply 16a.

  When the power generation operation is stopped by pressing a stop switch (not shown) during the power generation operation, or when the power generation operation is stopped according to the operation plan, the control device 15 stops the fuel cell system 1. (Stop processing) is performed. The control device 15 stops the supply of the reforming raw material and the reformed water to the evaporation unit 32 and stops the supply of the reformed gas and air to the fuel cell 34. At this time, when the fuel cell 34 is generating electricity with the remaining raw material, the electric power generated by the fuel cell 34 is supplied to the heaters 36a1, 36a2, etc. and consumed. When the power generation of the fuel cell 34 with the remaining raw materials is completed, the stop operation is completed.

  In addition, when the fuel cell system 1 is in the start operation, the power generation operation, or the stop operation, the power switching device 70 is switched to the off state, so that power is supplied to the heating device 22b. Not.

  When such a stop operation ends, the fuel cell system 1 enters a standby state (standby state). During standby, the fuel cell system 1 is in a power generation stop state (that is, a start operation, a power generation operation, or a stop operation is not in progress) and waits for a power generation instruction (such as turning on a start switch). It is a state of being. That is, the state in which the fuel cell module 30 is not generating power is maintained.

  When the fuel cell system 1 is in a standby state, there is no exhaust heat from the fuel cell module 30, so heat exchange in the heat exchanger 12 is not performed. Therefore, in this case, the circulation pump 22a is not driven. Further, when the fuel cell system 1 is in the standby state, the power switching device 70 is switched to the off state, except when the second freeze prevention control described later is executed.

  Next, the independent power generation operation of the fuel cell system 1 will be described. The independent power generation operation is an operation in which only the power generated by the fuel cell module 30 is supplied to the external power load 16b when the supply of power from the system power supply 16a is stopped (hereinafter referred to as a power failure). During the self-sustaining power generation operation, the control device 15 controls the auxiliary machine so as to maintain the power generated by the fuel cell 34 at a predetermined power (for example, half of the maximum output power). In this case, the fuel cell 34 is set to output the generated power at a first voltage value (for example, 300 V) during the self-sustaining power generation operation.

  Further, during the self-sustaining power generation operation, the power switching device 70 is switched to the direct current on state. Thereby, the heating device 22b consumes surplus power that is not consumed by the external power load 16b among the power generated by the fuel cell module 30 during the self-sustaining power generation operation. That is, the heating device 22b is a surplus power consuming heater that consumes surplus power during the self-sustaining power generation operation.

  Further, when the fuel cell system 1 is in the start-up operation, the power generation operation, the stop operation, and the self-sustaining power generation operation, the exhaust heat recovery system 20 recovers the exhaust heat from the fuel cell module 30 into the hot water in the hot water storage tank 21. The That is, as described above, hot water circulates in the hot water circulation path 22 by driving the circulation pump 22a and is heated by the exhaust heat from the fuel cell module 30 in the heat exchanger 12.

  In this case, the flow rate (flow rate per unit time) of hot water sent out by the circulation pump 22a is adjusted so that the first detected temperature detected by the first temperature sensor 22c becomes the circulation temperature (for example, 60 ° C.). Thus, the drive amount of the circulation pump 22a is feedback controlled.

  Next, the first freezing prevention control and the second freezing prevention control performed by the control device 15 will be described with reference to the flowchart shown in FIG. The first freezing prevention control and the second freezing prevention control are the hot water circulation path 22, the water supply path 23, the hot water outlet path 24a, the water supply branch path 24b, the mixed hot water outlet path 24d, and the bypass path 25 (hereinafter referred to as each flow path). ) Is a control that suppresses freezing of hot water.

  First, the case where the fuel cell system 1 is in a power generation operation and the outside air temperature is relatively low will be described. In step S102, the control device 15 determines whether at least one of the first detection temperature, the second detection temperature, and the third detection temperature is equal to or lower than the first predetermined temperature. The first predetermined temperature is set to a relatively low temperature among the temperatures at which the hot and cold water in each flow path does not freeze. The first predetermined temperature is set to a temperature lower than the circulation temperature. The first predetermined temperature is 10 ° C., for example.

  During the power generation operation of the fuel cell system 1, the exhaust heat recovery system 20 operates so that the hot water flowing through the hot water circulation path 22 reaches the circulation temperature. Therefore, the first detected temperature detected by the first temperature sensor 22c is higher than the first predetermined temperature. In addition, when the outside air temperature is relatively low and the hot water supply device 40 does not supply hot water, the second and third detected temperatures detected by the second and third temperature sensors 23a and 24d1 gradually decrease. Thereby, when one of the second and third detected temperatures becomes equal to or lower than the first predetermined temperature, the control device 15 determines “YES” in step S102, and executes the first freeze prevention control in step S106. (First freeze prevention control unit).

  The first antifreezing control is a control for driving the valve body 52 of the mixing valve 50 to position the valve body 52 at the mixing position and driving the circulation pump 22a to circulate hot water. In the present embodiment, the first freeze prevention control is performed so that the bypass valve 25a is opened.

  In the first freeze prevention control, the driving amount of the circulation pump 22a is controlled so that the flow rate delivered by the circulation pump 22a is constant at a predetermined flow rate (for example, 0.2 L / min). Thereby, the hot water circulates in the hot water circulation path 22 at a predetermined flow rate. The hot water circulation path 22, the water supply path 23, and the hot water outlet path 24 a communicate with each other via the hot water storage tank 21.

  Further, since the ports 51a to 51c communicate with each other when the position of the valve body 52 of the mixing valve 50 is located at the mixing position, the hot water outlet passage 24a, the water supply branch passage 24b, and the water supply passage 23 are connected via the mixing valve 50. Communicate. Accordingly, the hot water in the hot water storage tank 21 is led to the hot water outlet path 24a by driving the circulation pump 22a, and circulates back from the mixing valve 50 to the hot water tank 21 through the water supply branch path 24b and the water supply path 23 ( (See dashed arrows in FIG. 1).

  At this time, since the bypass valve 25a is in an open state, the hot water outlet passage 24a, the mixed hot water outlet passage 24d, the bypass passage 25, and the water supply passage 23 communicate with each other through the mixing valve 50. Thereby, the hot water of the hot water storage tank 21 is led out to the hot water outlet path 24a by driving the circulation pump 22a, and returns from the mixing valve 50 to the hot water tank 21 through the mixed hot water outlet path 24d, the bypass path 25 and the water supply path 23. (Refer to the broken arrow in FIG. 1). Note that when the first freeze prevention control is being executed, the feedback control of the circulation pump 22a described above is stopped.

  When the fuel cell system 1 is in the power generation operation, the exhaust heat recovery system 20 is operating, and thus the exhaust heat is recovered in hot water. Thereby, the temperature of the hot water of each flow path rises. Note that, when the fuel cell system 1 is in the power generation operation, the power switching device 70 is in the off state, so that the hot water is not heated by the heating device 22b.

  Subsequently, the control device 15 determines whether or not a second predetermined time has elapsed since the first freeze prevention control was started in step S108. The second predetermined time is set to a time longer than the time for the hot water stored in the hot water storage tank 21 to make a round of each flow path from the time when the first freeze prevention control is started. The second predetermined time is, for example, 3 minutes.

  If the second predetermined time has not elapsed, the control device 15 determines “NO” in step S108, and repeatedly executes step S108. If the second predetermined time has elapsed, the control device 15 determines “YES” in step S108, and advances the program to step S110.

  In step S110, the control device 15 determines whether or not the first detected temperature detected by the first temperature sensor 22c is equal to or lower than a third predetermined temperature. The third predetermined temperature is set to a temperature higher than the first predetermined temperature and lower than the circulation temperature.

  Since the exhaust heat recovery system 20 is operating when the fuel cell system 1 is in the power generation operation, the temperature of the hot water stored in the hot water is higher than when the exhaust heat recovery system 20 is not operating. Is expensive. Accordingly, when the first detected temperature is higher than the third predetermined temperature, the hot water stored in the hot water storage tank 21 circulates through each flow path by the first freeze prevention control, thereby freezing the hot water in each flow path. Is suppressed. Therefore, in this case, the control device 15 determines “NO” in Step S110.

  Subsequently, in step S112, the control device 15 determines whether at least one of the first detection temperature, the second detection temperature, and the third detection temperature is equal to or lower than the first predetermined temperature in the same manner as in step S102. To do. When the first detection temperature, the second detection temperature, and the third detection temperature are higher than the first predetermined temperature due to an increase in the temperature of the hot water in each flow path by the first freeze prevention control, the control device 15 In S112, the determination is “NO” and the program proceeds to step S114.

  In step S114, the control device 15 determines whether or not a third predetermined time has elapsed since the start of the first freeze prevention control. The third predetermined time is set to be longer than the second predetermined time. The third predetermined time is, for example, 15 minutes. When the third predetermined time has not elapsed, the control device 15 repeatedly executes steps S112 and S114.

  When the fuel cell system 1 is in the power generation operation, since the exhaust heat recovery system 20 is operating, the hot water is heated so that the temperature of the hot water flowing through the hot water circulation path 22 becomes the circulation temperature. As a result, the first detection temperature, the second detection temperature, and the third detection temperature do not fall below the first predetermined temperature. Therefore, the control device 15 repeatedly determines “NO” in steps S112 and S114 until the third predetermined time has elapsed.

  And when 3rd predetermined time passes, the control apparatus 15 determines with "YES" in step S114. And the control apparatus 15 complete | finishes 1st freezing prevention control in step S116, and returns a program to step S102. When the fuel cell system 1 is in the power generation operation, when the first freeze prevention control is completed, the feedback control of the circulation pump 22a described above is executed.

  Even when the fuel cell system 1 described above is in a power generation operation and the outside air temperature is relatively low, the first detection temperature, the second detection temperature, and the third detection temperature are higher than the first predetermined temperature. In this case, the control device 15 determines “NO” in step S102.

  Then, in step S104, the control device 15 determines whether or not the outside air detected temperature detected by the outside air temperature sensor 60 is equal to or lower than the second predetermined temperature and the mixed hot water non-derivation time is equal to or longer than the first predetermined time. To do. The second predetermined temperature is set to a relatively low temperature among the temperatures at which water does not freeze. The second predetermined temperature is set to a temperature lower than the first predetermined temperature. The second predetermined temperature is, for example, 5 ° C. The first predetermined time is set to a relatively short time among the times when the hot water in each flow path is frozen when the outside air temperature is relatively low. The first predetermined time is, for example, 6 hours.

  When the outside air temperature is higher than the second predetermined temperature due to the relatively high outside air temperature, or when the mixed water non-derivation time is shorter than the first predetermined time due to the hot water supply performed by the hot water supply device 40, the control device 15 Determines “NO” in step S104, and returns the program to step S102.

  On the other hand, since the outside air temperature is relatively low, the outside air detection temperature is equal to or lower than the second predetermined temperature, and the hot water supply apparatus 40 does not perform hot water supply for a relatively long time, so that the mixed hot water non-derived time is equal to or longer than the first predetermined time If so, the control device 15 determines “YES” in step S104, and starts the first freeze prevention control in step S106.

  Thus, the control device 15 is detected by the outside air temperature sensor 60 when at least one of the first detection temperature, the second detection temperature, and the third detection temperature is equal to or lower than the first predetermined temperature. The first antifreeze control is executed when the temperature (outside air detection temperature) is equal to or lower than the second predetermined temperature and the time during which mixed hot water is not led out from the mixing valve 50 (mixed hot water non-derived time) is equal to or longer than the first predetermined time. To do. When the fuel cell system 1 is in the power generation operation, the control device 15 executes Steps S106 to S114 as described above.

  Even when the fuel cell system 1 is in the start-up operation and the stop operation, the control device 15 executes Steps S102 to S114 as in the case where the fuel cell system 1 is in the power generation operation. As described above, when the fuel cell system 1 is in the power generation operation, the start-up operation, and the stop operation, the temperature of the hot water in each flow path rises only by the first freeze prevention control. It is suppressed.

  Next, the case where the fuel cell system 1 is in a standby state and the outside air temperature is relatively low will be described. When the fuel cell system 1 is in a standby state, power generation by the fuel cell module 30 is not performed, and the exhaust heat recovery system 20 is not operating, so the temperature of hot water in each flow path is lowered by the outside air.

  Accordingly, when at least one of the first detection temperature, the second detection temperature, and the third detection temperature becomes equal to or lower than the first predetermined temperature, or the outside air detection temperature is equal to or lower than the second predetermined temperature and the mixed hot water non-derivation time is reached. When it becomes more than 1st predetermined time, the control apparatus 15 determines with "YES" in step S102 or step S104, and starts 1st freezing prevention control in step S106. Furthermore, the control apparatus 15 performs step S108 as mentioned above.

  Since the temperature of the hot water stored in the hot water tank 21 is relatively high, the first detection temperature is higher than the third predetermined temperature, and all of the first detection temperature, the second detection temperature, and the third detection temperature are the first. When the temperature is higher than one predetermined temperature, the control device 15 determines “NO” in steps S110 and S112. In this case, the control device 15 repeatedly executes steps S112 and S114 until the third predetermined time has elapsed.

  Further, in this case, when the third predetermined time has elapsed, the control device 15 returns to step S102. Therefore, since the temperature of the hot water stored in the hot water tank 21 is relatively high, the first detection temperature is higher than the third predetermined temperature, and further, all of the first detection temperature, the second detection temperature, and the third detection temperature. Is higher than the first predetermined temperature, the control device 15 repeatedly executes steps S102 to S116.

  When the fuel cell system 1 is in the standby state and the exhaust heat recovery system 20 is not operating, the temperature of the hot water storage tank 21 and the hot water in each flow path gradually decreases depending on the outside air temperature. Thereby, in the case where the first freeze prevention control is executed, when the first detected temperature becomes equal to or lower than the third predetermined temperature, or at least one of the first detected temperature, the second detected temperature, and the third detected temperature. When any one becomes below 1st predetermined temperature, the control apparatus 15 determines with "YES" in step S110 or step S112, and advances a program to step S118.

  In step S118, the control device 15 executes the second freeze prevention control (second freeze prevention control unit). The second freeze prevention control is a control for heating the hot water with the heating device 22b. Thus, when the second predetermined time has elapsed from the time when the first antifreezing control is started, the control device 15 has a first detected temperature that is lower than the third predetermined temperature higher than the first predetermined temperature, or When at least one of the first detection temperature, the second detection temperature, and the third detection temperature is equal to or lower than the first predetermined temperature, the second freeze prevention control is executed. At this time, the control device 15 simultaneously executes the first freeze prevention control and the second freeze prevention control.

  When the second freeze prevention control is started, the control device 15 switches the power switching device 70 from the off state to the alternating current on state. Specifically, the control device 15 supplies the AC voltage to the heating device 22b at the second voltage value by the power switching device 70 for a fourth predetermined time (for example, 5 minutes) from the time when the second antifreezing control is started. Output. The fourth predetermined time is set to a time longer than the time for hot water heated by the heating device 22b to go through each flow path. When the fourth predetermined time has elapsed, the control device 15 switches the second voltage value to the third voltage value by the power switching device 70 and outputs an AC voltage to the heating device 22b. Thereby, since the hot water circulating through the hot water circulation path 22 is heated by the heating device 22b, the temperature of the hot water in each flow path rises.

  Subsequently, in step S120, the control device 15 determines whether or not a fifth predetermined time has elapsed since the start of the second freeze prevention control. The fifth predetermined time is set to be longer than the fourth predetermined time. The fifth predetermined time is, for example, 15 minutes. If the fifth predetermined time has not elapsed, the control device 15 determines “NO” in step S120, and repeatedly executes step S120.

  On the other hand, when the fifth predetermined time has elapsed, the control device 15 determines “YES” in step S120. And the control apparatus 15 complete | finishes 1st freezing prevention control and 2nd freezing prevention control in step S122, and returns a program to step S102. And when the temperature of the hot water of each flow path falls again with external temperature, as mentioned above, step S102-S122 are performed again.

  Next, a case where the fuel cell system 1 is in a self-sustaining power generation operation will be described. In this case, as in the case where the fuel cell system 1 is in the power generation operation, the exhaust heat recovery system 20 is operating, so that the exhaust heat is recovered in the hot water. Therefore, when the first freeze prevention control is performed, the temperature of the hot water in each flow path rises, so that the freezing of the hot water in each flow path is suppressed. That is, in this case, the second freeze prevention control is not executed. In addition, when the fuel cell system 1 is in the self-sustained power generation operation, since the power switching device 70 is in the DC on state, the hot water is heated by the heating device 22b.

  According to the present embodiment, the fuel cell system 1 (cogeneration system) includes a fuel cell module 30, a hot water storage tank 21 for storing hot water, a hot water circulation path 22 through which hot water stored in the hot water storage tank 21 circulates, A heat pump provided in the hot water circulation path 22 for circulating hot water and a heat exchange provided in the hot water circulation path 22 for exchanging heat between the exhaust heat from the fuel cell module 30 and hot water stored in the hot water tank 21. The valve body 52 is driven by being connected to the water heater 12, the water supply passage 23 for supplying water from the water source W to the hot water storage tank 21, the hot water supply passage 24 a through which the hot water in the hot water storage tank 21 is led out, and the water supply path 23. Thus, by setting the position of the valve body 52 to a mixing position where the hot water from the hot water outlet passage 24a and the water from the water supply passage 23 are mixed, mixed hot water in which hot water and water are mixed is generated. Both are provided in a mixing valve 50 for deriving mixed hot water, a mixed hot water deriving path 24 d for deriving mixed hot water derived from the mixing valve 50 to the hot water supply device 40, and a hot water circulation path 22 for detecting the temperature of the hot water. One temperature sensor 22c, a second temperature sensor 23a provided in the water supply passage 23 for detecting the temperature of the water, a third temperature sensor 24d1 provided in the mixed hot water outlet passage 24d for detecting the temperature of the mixed hot water, and fuel And a control device 15 that controls at least the battery module 30. The control device 15 uses a first detected temperature that is a temperature detected by the first temperature sensor 22c, a second detected temperature that is a temperature detected by the second temperature sensor 23a, and a temperature detected by the third temperature sensor 24d1. When at least one of the third detected temperatures is equal to or lower than the first predetermined temperature, the valve body 52 is driven to position the valve body 52 at the mixing position, and the circulation pump 22a is driven. A first anti-freezing control unit (step S106) that executes first anti-freezing control for circulating hot and cold water.

  According to this, the hot water stored in the hot water storage tank 21 circulates in the hot water circulation path 22 and the hot water in the hot water storage tank 21 is led out to the hot water outlet path 24a by the first freeze prevention control, and the mixing valve 50 and the water supply It circulates through the path 23 so as to return to the hot water tank 21. Therefore, not only the hot water circulation path 22 through which hot water in the hot water tank 21 circulates, but also the hot water outlet path 24a, the mixing valve 50 and the mixed hot water outlet path 24d between the hot water tank 21 and the hot water supply device 40, the hot water tank 21 and the water source. The temperature of the hot water in the water supply channel 23 with W rises. Therefore, freezing of the flow path connected to the hot water tank 21 can be suppressed.

  Moreover, since the temperature of the hot water in each flow path rises by the first freeze prevention control, a heater or the like for heating each flow path for suppressing freezing of the hot water in each flow path can be eliminated. Therefore, an increase in the number of parts of the fuel cell system 1 and an increase in cost of the fuel cell system 1 can be suppressed.

  The fuel cell system 1 further includes an outside air temperature sensor 60 that detects the temperature of the outside air. The first freezing prevention control unit (step S106) of the control device 15 is configured such that at least one of the first detection temperature, the second detection temperature, and the third detection temperature is equal to or lower than the first predetermined temperature, or When the temperature (outside air detection temperature) detected by the outside air temperature sensor 60 is equal to or lower than the second predetermined temperature and the time when the mixed hot water is not led out from the mixing valve 50 (the mixed hot water non-leading time) is equal to or longer than the first predetermined time, The first freeze prevention control is executed.

  According to this, the first freezing prevention control unit (step S106) does not depend on the temperatures detected by the temperature sensors 22c, 23a, 24d1 provided in the hot water circulation path 22, the hot water outlet path 24a, and the water supply path 23. First, the first freeze prevention control is executed. Therefore, even when abnormality occurs in one of the temperature sensors 22c, 23a, and 24d1, freezing of hot water in the flow path connected to the hot water tank 21 can be suppressed.

  The fuel cell system 1 further includes a heating device 22b that is provided in the hot water circulation path 22 and heats the hot water by being supplied with electric power. When the second predetermined time has elapsed from the time when the first freeze prevention control is started by the first freeze prevention control unit (step S106), the control device 15 has a third predetermined temperature at which the first detected temperature is higher than the first predetermined temperature. 2nd anti-freezing control which heats hot and cold water by heating device 22b when it is below, or when at least one temperature among the 1st detection temperature, the 2nd detection temperature, and the 3rd detection temperature is below the 1st predetermined temperature A second anti-freezing control unit (step S118).

  According to this, even when the temperature of the hot water in the hot water storage tank 21 is lowered when the first freeze prevention control is performed, the heating device 22b heats the hot water by the second freeze prevention control, so Temperature rises. Therefore, freezing of the hot water in the flow path connected to the hot water tank 21 can be reliably suppressed.

  Further, the heating device 22b is operated by the fuel cell module 30 during a self-sustaining power generation operation in which only the power generated by the fuel cell module 30 is supplied to the external power load 16b when the supply of power from the system power supply 16a is stopped. It is a surplus power consumption heater that consumes surplus power that is not consumed by the external power load 16b among the generated power.

  According to this, the fuel cell system 1 uses the surplus power consumption heater used during the self-sustaining power generation operation as the heating device 22b. Therefore, the second freeze prevention control can be performed without increasing the number of parts of the fuel cell system 1 and increasing the cost of the fuel cell system 1.

  The fuel cell system 1 is electrically connected to each of the fuel cell module 30, the system power supply 16a, and the heating device 22b, and switches between the power generated by the fuel cell module 30 and the power supplied from the system power supply 16a. And a power switching device 70 to be supplied to the heating device 22b.

  According to this, the electric power from the system | strain power supply 16a can be supplied to the heating apparatus 22b. Therefore, the second freeze prevention control can be performed even when the fuel cell module 30 is not generating power. For example, even when the reforming raw material is not supplied from the supply source Gs due to an abnormality in the supply source Gs, the first freezing prevention control and the second freezing prevention control can be performed by the electric power from the system power supply 16a.

  Further, the fuel cell module 30 outputs the generated power at the first voltage value during the self-sustaining power generation operation. When the power switching device 70 supplies power from the system power supply 16a to the heating device 22b, the power switching device 70 supplies power supplied from the system power supply 16a to a second voltage value smaller than the first voltage value and a third voltage smaller than the second voltage value. It is provided so that it can be switched to one of the voltage values.

  According to this, when the electric power from the system power supply 16a is supplied to the heating device 22b, the voltage value is smaller than when the electric power from the fuel cell module 30 is supplied to the heating device 22b. The safety of the second freeze prevention control can be improved.

  In addition, the power generation device of the cogeneration system (fuel cell system 1) in the present embodiment includes a fuel cell 34 that generates power using fuel and an oxidant gas, an evaporation unit 32 that generates water vapor from reformed water, and a supply source Gs. The fuel cell module 30 includes a reforming unit 33 that generates fuel from the reforming raw material and the water vapor from the evaporation unit 32 and supplies the fuel to the fuel cell 34.

  In the above-described embodiment, an example of a cogeneration system has been shown. However, the present invention is not limited to this, and other configurations can be adopted. For example, the power generation unit 10 of the above-described cogeneration system uses the fuel cell module 30, but instead of this, a power generation unit using an internal combustion engine (not shown) such as a gas engine and a generator (not shown). 10 may be configured. In this case, the power generator of the present invention is configured using an internal combustion engine and a generator.

  In the above-described embodiment, the control device 15 opens the bypass valve 25a in the first freeze prevention control. Instead, the control device 15 keeps the bypass valve 25a closed. Also good. Furthermore, the control device 15 may omit step S104. Further, the control device 15 may omit steps S114 and S116.

  In the above-described embodiment, the control device 15 switches the power switching device 70 to the off state or the direct current on state in the first freeze prevention control. Instead, the control device 15 switches the power switching device 70 to the alternating current on state. You may make it switch to a state.

  Moreover, in embodiment mentioned above, the control apparatus 15 outputs the electric power from the electric power switching apparatus 70 with respect to the heating apparatus 22b with 2nd voltage value by 2nd freezing prevention control, and is 4th predetermined time. When it has passed, the output is switched to the third voltage value. On the other hand, the control device 15 outputs the power from the power switching device 70 to the heating device 22b at the second voltage value constant or the third voltage value constant in the second freeze prevention control. You may make it do. In addition, the control device 15 outputs the power from the power switching device 70 to the heating device 22b as the second voltage value in the second freeze prevention control, and then the first detected temperature is set to the fourth predetermined temperature ( For example, when the temperature reaches 20 ° C., the output may be switched to the third voltage value.

  In the above-described embodiment, the heating device 22b is a surplus power consumption heater. However, instead of this, the heating device 22b may be provided separately from the surplus power consumption heater.

  In the above-described embodiment, the heating device 22b is set to have a constant predetermined electric resistance value. Instead, the heating device 22b may be provided so that the electric resistance value can be varied. In this case, in the second freeze prevention control, the control device 15 may control the electric resistance value of the heating device 22b so that the first detected temperature becomes the fifth predetermined temperature (for example, 20 ° C.).

  In addition, within the range not departing from the gist of the present invention, the number and arrangement position of each temperature sensor 22c, 23a, 24d1, each predetermined temperature, each predetermined time, the second voltage value and the third voltage value in the second freeze prevention control, The switching timing and the driving method of the circulation pump 22a may be changed.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system (cogeneration system), 10 ... Power generation unit, 11 (30) ... Fuel cell module, 12 ... Heat exchanger, 15 ... Control device, 16a ... System power supply, 16b ... External power load, 20 ... Exhaust Heat recovery system, 21 ... hot water tank, 22 ... hot water circulation path, 22a ... circulation pump, 22b ... heating device, 22c ... first temperature sensor, 23 ... water supply path, 23a ... second temperature sensor, 24a ... hot water discharge path, 24b ... Water supply branch path, 24c (50) ... Mixing valve, 24d ... Mixed hot water outlet path, 24d1 ... Third temperature sensor, 32 ... Evaporation section, 33 ... Reforming section, 34 ... Fuel cell, 40 ... Hot water supply apparatus, 52 DESCRIPTION OF SYMBOLS ... Valve body, 60 ... Outside air temperature sensor, 70 ... Electric power switching device, Gs ... Supply source, S106 ... First freezing prevention control part, S118 ... Second freezing prevention control part, W ... Water source.

Claims (7)

A power generator,
A hot water storage tank for storing hot water,
A hot water circulation path through which the hot water stored in the hot water tank circulates;
A circulation pump provided in the hot water circulation path for circulating the hot water;
A heat exchanger provided in the hot water circulation path for exchanging heat between the exhaust heat from the power generation device and the hot water stored in the hot water storage tank;
A water supply channel for supplying water from a water source to the hot water storage tank;
The hot water supply path from which the hot water of the hot water storage tank is led out is connected to the hot water supply path and the water supply path, respectively, and the valve body is driven to change the position of the valve body from the hot water supply path to the hot water and the water supply path. A mixing valve for generating the mixed hot water in which the hot water and the water are mixed, and for deriving the mixed hot water, by setting the mixing position to mix the water from
A mixed hot water outlet passage for leading the mixed hot water led out from the mixing valve to a hot water supply device;
A first temperature sensor provided in the hot water circulation path for detecting the temperature of the hot water;
A second temperature sensor provided in the water supply channel for detecting the temperature of the water;
A third temperature sensor that is provided in the mixed hot water outlet and detects the temperature of the mixed hot water;
A cogeneration system comprising at least a control device for controlling the power generation device,
The controller is
A first detected temperature that is a temperature detected by the first temperature sensor, a second detected temperature that is a temperature detected by the second temperature sensor, and a third detected temperature that is a temperature detected by the third temperature sensor If at least one of the temperatures is equal to or lower than the first predetermined temperature,
A first anti-freezing control unit for driving the valve body to position the valve body at the mixing position, and driving the circulation pump to circulate the hot water. Cogeneration system. It further includes an outside air temperature sensor that detects the temperature of the outside air,
The first freeze prevention control unit
When at least one of the first detection temperature, the second detection temperature, and the third detection temperature is equal to or lower than the first predetermined temperature, or the temperature detected by the outside air temperature sensor is a second temperature. 2. The cogeneration system according to claim 1, wherein the first antifreezing control is executed when the temperature is equal to or lower than a predetermined temperature and the time when the mixed hot water is not led out from the mixing valve is equal to or longer than a first predetermined time. A heating device that is provided in the hot water circulation path and that heats the hot water by being supplied with electric power;
The controller is
When the first predetermined temperature is equal to or lower than the third predetermined temperature higher than the first predetermined temperature when the second predetermined time has elapsed from the time when the first antifreezing control is started by the first antifreezing control unit, Alternatively, when at least one of the first detection temperature, the second detection temperature, and the third detection temperature is equal to or lower than the first predetermined temperature,
The cogeneration system according to claim 1 or 2, further comprising a second anti-freezing control unit that performs a second anti-freezing control for heating the hot water with the heating device.   The heating device is configured such that, during a self-sustaining power generation operation in which only power generated by the power generation device is supplied to an external power load when supply of power from a system power supply is stopped, of the power generated by the power generation device The cogeneration system according to claim 3, which is a surplus power consumption heater that consumes surplus power that is not consumed by the external power load.   A power switching device that is electrically connected to each of the power generation device, the system power supply, and the heating device, and switches between the power generated by the power generation device and the power supplied from the system power supply and supplies the power to the heating device The cogeneration system according to claim 4, further comprising: The power generator outputs the generated power at the first voltage value during the self-sustaining power generation operation,
When the power switching device supplies power from the system power source to the heating device, the power supplied from the system power source is smaller than the second voltage value and the second voltage value smaller than the first voltage value. The cogeneration system according to claim 5, wherein the cogeneration system is provided so as to be able to output by switching to one of the third voltage values.   The power generation device includes: a fuel cell that generates power using fuel and an oxidant gas; an evaporator that generates steam from reformed water; a reforming material from a supply source; and the steam from the evaporator. A cogeneration system according to any one of claims 1 to 6, which is a fuel cell module including a reforming unit that generates and supplies the fuel cell to the fuel cell.

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