JP2007127301A - Protection method of cogeneration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection method of a cogeneration system capable of increasing energy efficiency without damaging a heat exchanger by abnormal rise of temperature and pressure in the heat exchanger, when the quantity of water supplied to the heat exchanger is reduced or water supply is cut, and not enlarging the system. <P>SOLUTION: This protection method of the cogeneration system wherein electricity and exhaust gas of high temperature are generated by a power generation heat generation unit such as a fuel cell, the electricity is supplied to a load or a power system through an electric circuit, the exhaust gas is supplied to the heat exchanger, and the water is supplied to a water passage of the heat exchanger so that a temperature of the water is changed to supply hot water. When the quantity of water supplied to the heat exchanger is reduced, or the water supply is cut, the air or a nitrogen gas is mixed to the exhaust gas to lower a temperature, thus a temperature or pressure of the heat exchanger is prevented from being abnormally increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for protecting a cogeneration system for preventing a heat exchanger provided in the cogeneration system from becoming abnormally high temperature and pressure.

  Conventionally, cogeneration that effectively uses energy and reduces the burden on the environment by generating electricity with a power generator / heater such as a fuel cell, gas turbine, or gas engine, and using the exhaust gas generated at that time for hot water supply A system has been proposed. (For example, see Patent Document 1 and Patent Document 2.)

  FIG. 6 is a diagram showing a configuration of a conventional cogeneration system protection method, in which a fuel cell is used as a power generation heat generator. In the figure, an operating air supply source 2 having a compressor or a blower boosts operating air to a fuel supply unit 1, and a gas supply source 3 having a compressor or a blower boosts a city gas and has a pump. The pure water supply source 4 supplies pure water.

  The fuel supply unit 1 supplies the supplied operating air to the fuel cell 5 by opening and closing the fuel air valve 11, adjusting the flow rate with the fuel air flow rate regulator 12. Further, the fuel cell cooling air valve 13 is opened and closed, the flow rate is adjusted by the fuel cell cooling flow rate regulator 14 and supplied to the fuel cell 5 to cool the cells in the fuel cell 5. Further, the supplied city gas is supplied to the fuel cell 5 by opening and closing the gas valve 15 and adjusting the flow rate with a gas flow rate regulator. Further, the supplied pure water is supplied to the fuel cell 5 through the pure water flow meter 18 by opening and closing the pure water valve 17.

  The fuel cell 5 is a high-temperature fuel cell such as a solid electrolyte fuel cell, a phosphoric acid fuel cell, or a molten carbonate fuel cell, and generates hydrogen from supplied city gas and pure water. And oxygen in the fuel air are chemically reacted to generate electricity and hot exhaust gas.

  The exhaust gas supplied from the fuel cell 5 is supplied to the heat exchanger 7 through the exhaust pipe 6. This exhaust pipe 6 is provided with an exhaust gas switching valve 8. The exhaust gas switching valve 8 is normally connected to a flow path for supplying exhaust gas supplied from the fuel cell 5 to the heat exchanger 7. And when the water stop detection signal S1 from the water stop detection sensor 9 mentioned later is input, in order to exhaust the exhaust gas which the fuel cell 5 supplies outside, a flow path is switched to the bypass piping 10. FIG. A heat insulating material is wound around the exhaust pipe 6, the exhaust gas switching valve 8 and the bypass pipe 10 in order to reduce heat radiation to the air.

  The cold water supply source 20 supplies cold water to the heat exchanger 7. The water failure detection sensor 9 detects that the amount of cold water supplied by the cold water supply source 20 has been reduced or has stopped, and outputs a water failure detection signal S1 to the exhaust gas switching valve 8. The heat exchanger 7 converts the supplied cold water into hot water by the exhaust gas supplied from the fuel cell 5, supplies the hot water to the hot water tank 21, and ejects the exhaust gas to the outside. The hot water supplied to the hot water storage tank 21 is used for hot water supply or the like.

The operation will be described below.
In FIG. 6, the flow of air, city gas, and pure water supplied from the operating air supply source 2, gas supply source 3, and pure water supply source 4 is adjusted by the fuel supply unit 1 and supplied to the fuel cell 5. Is done. The fuel cell 5 generates hydrogen from the supplied city gas and pure water, and chemically reacts the hydrogen with oxygen in the fuel air to generate electricity and high-temperature exhaust gas. The fuel cell cooling air cools the cells in the fuel cell 5. The electricity generated by the fuel cell 5 is supplied to a load or power system (not shown).

  The fuel cell 5 supplies the exhaust gas to the heat exchanger 7 through the exhaust gas switching valve 8. The heat exchanger 7 converts the cold water supplied from the cold water supply source 20 into exhaust water supplied by the fuel cell 5, for example, converts it into hot water of about 90 degrees and supplies the hot water to the hot water tank 21. The hot water supplied to the hot water storage tank 21 is used for hot water supply or the like. Moreover, the heat exchanger 7 injects the exhaust gas which temperature fell by converting cold water into warm water to the exterior.

  As described above, the cold water supply source 20 supplies cold water to the heat exchanger 7, but this water supply amount may be reduced or shut off. For example, when the cold water entering the cold water supply source 20 is cut off, when the cold water supply source 20 breaks down, or when the cold water is lowered or stopped due to maintenance of the cold water supply source 20, or the hot water is prolonged. This is a case where the supply of cold water is stopped when not in use for a period. In these cases, water stays in the water channel of the heat exchanger 7, and the staying water is heated by the exhaust gas supplied from the fuel cell 5 and expands into water vapor. And the pressure in piping in the heat exchanger 7 may rise abnormally, and the heat exchanger 7 may be damaged. Moreover, the exhaust gas supplied to the heat exchanger 7 is exhausted by reducing its temperature by converting the temperature from cold water to hot water. However, since the temperature cannot be lowered because cold water is not supplied to the heat exchanger, the heat exchanger 7 may be damaged.

In this case, the temperature of the heat exchanger 7 may be lowered by stopping the fuel cell 5 and stopping the exhaust gas to the heat exchanger 7. However, the high temperature fuel cell takes a long time to start. Therefore, it is required to repair and maintain peripheral devices while the fuel cell 5 is in operation. Therefore, conventionally, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or shut down, the water stop detection sensor 9 outputs a water stop detection signal S1 to the exhaust gas switching valve 8, and the exhaust gas switching valve. 8 switches the flow path of the exhaust gas from the flow path to the heat exchanger 7 to the flow path to the bypass pipe 10 to eject the exhaust gas to the outside. As a result, it is possible to prevent the temperature of the heat exchanger 7 from rising abnormally and being damaged. However, it has the problems described later.
JP-A-5-93593 JP 2002-295867 A

  As described above, the exhaust pipe 6 from the fuel cell 5 is provided with the exhaust gas switching valve 8. The exhaust gas switching valve 8 is a large valve because a large amount of exhaust gas is supplied from the fuel cell 5 to the heat exchanger 7. In addition, a heat insulating material is wound around the exhaust gas switching valve 8 in order to reduce heat radiation to the air. However, since the heat cannot be completely cut off, the heat of the exhaust gas escapes from the exhaust gas switching valve 8 and the bypass pipe 10 during the normal operation of the fuel cell 5. For this reason, sufficient heat is not supplied to the heat exchanger 7 and energy efficiency is reduced. Further, the exhaust gas switching valve 8 is large, and there is a problem that the system becomes large because a heat insulating material is wound.

  In the present invention, when the amount of water supplied to the heat exchanger is reduced or water is cut off, the temperature and pressure of the heat exchanger will not be abnormally increased and damaged, and the energy efficiency can be increased, and the system is large. It aims at providing the protection method of the cogeneration system which does not become.

In order to achieve the above object, the first invention is a method for protecting the cogeneration system shown in FIG. 1, wherein electric and high-temperature exhaust gas is generated by a power generation heat generator such as a fuel cell, a gas turbine, or a gas engine. The electricity is supplied to a load or an electric power system through an electric circuit, and the exhaust gas is supplied to a heat exchanger and supplied to a water channel of the heat exchanger to be changed into warm water to supply hot water. In the method
Preventing the heat exchanger from becoming abnormally high temperature and pressure by reducing the temperature by mixing air or nitrogen gas into the exhaust gas when the amount of water supplied to the heat exchanger decreases or shuts down. This is a characteristic cogeneration system protection method.

The second invention is a method for protecting the cogeneration system shown in FIG. 3, wherein electricity and high-temperature exhaust gas are generated by a power generation heat generator such as a fuel cell, a gas turbine, or a gas engine, and the electricity is an electric circuit. In the cogeneration system protection method of supplying hot water via a load or power system, supplying the exhaust gas to a heat exchanger, supplying water to the water channel of the heat exchanger, and changing to hot water,
When the amount of water supplied to the heat exchanger is reduced or water is cut off, water is drained from the water channel of the heat exchanger, and air or nitrogen gas is injected into the water channel of the heat exchanger so that the temperature of the heat exchanger The cogeneration system protection method is characterized in that the heat exchanger is prevented from becoming abnormally high temperature and pressure by lowering the temperature.

  3rd invention is a protection method of the cogeneration system shown in FIG. 4, Comprising: When the amount of water supply to the said heat exchanger falls or water-stops, it drains water from the water channel of the said heat exchanger. The cogeneration system protection method according to the first aspect of the present invention.

  4th invention is the protection method of the cogeneration system shown in FIG. 5, Comprising: When the amount of water supply to the said heat exchanger falls or it stops water, while draining water from the water channel of the said heat exchanger, the said heat The cogeneration system protection method according to the first aspect of the present invention, wherein air or nitrogen gas is injected into a water channel of the exchanger to lower the temperature of the heat exchanger.

  According to a first aspect of the present invention, there is provided a cogeneration system protection method in which electricity and high-temperature exhaust gas are generated by a power generator / heater such as a fuel cell, and electricity is supplied to a load or an electric power system through an electric circuit. In the protection method of a cogeneration system that supplies water to the heat exchanger and supplies it to the water channel of the heat exchanger and changes it into hot water to supply hot water, when the amount of water supplied to the heat exchanger decreases or shuts down, air or nitrogen is added to the exhaust gas. The heat exchanger is prevented from becoming abnormally high temperature and pressure by mixing gas and lowering the temperature.

  As a result, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or shut down, the temperature of the exhaust gas supplied to the heat exchanger 7 by the cooling air can be lowered. The heat exchanger 7 is not damaged due to an abnormal rise in temperature. Further, since the exhaust gas switching valve 8 and the bypass pipe 10 as in the prior art are not provided, the heat of the exhaust gas does not escape to these devices during normal operation, and sufficient heat is supplied to the heat exchanger 7. Energy efficiency can be increased. Further, since there is no need to provide a large exhaust gas switching valve 8 as in the prior art, the system does not increase in size.

  The cogeneration system protection method according to the second aspect of the invention generates electricity and high-temperature exhaust gas by a power generator / heater such as a fuel cell, supplies electricity to a load or an electric power system via an electric circuit, and the exhaust gas is heat. In the protection method of a cogeneration system that supplies water to the heat exchanger and supplies water to the heat exchanger water and changes it to hot water to supply hot water, when the amount of water supplied to the heat exchanger decreases or shuts down, the heat exchanger water channel In addition to draining water from the water, air or nitrogen gas is injected into the water channel of the heat exchanger to lower the temperature of the heat exchanger, thereby preventing the heat exchanger from becoming abnormally high temperature and pressure.

  As a result, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or water is cut off, the hot water is retained in the water channel 28 of the heat exchanger 7 in order to drain the warm water from the drain switching valve 29. There is no risk of damage to the heat exchanger caused by heating with exhaust gas to form water vapor and expanding to increase pressure. Further, air or nitrogen gas ejected from the cooling air supply source 22 is injected from the intake air switching valve 27 into the water passage 28 of the heat exchanger 7 to cool the water passage 28, so that the temperature of the heat exchanger 7 is increased. Can be prevented, and damage to the heat exchanger 7 can be prevented.

  In addition to the first invention, the protection method for the cogeneration system of the third invention drains water from the water channel of the heat exchanger when the amount of water supplied to the heat exchanger is reduced or stopped.

  As a result, in addition to the effect of the protection method of the cogeneration system of the first embodiment, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or shut down, the water in the water channel of the heat exchanger In order to drain the water from the drainage switching valve 29, hot water stays in the water passage 28 of the heat exchanger 7 and is heated by the exhaust gas to become water vapor, which may expand and increase the pressure, possibly causing damage to the heat exchanger. There is no. Therefore, damage to the heat exchanger 7 can be prevented.

  In addition to the first invention, the cogeneration system protection method of the fourth invention drains water from the water channel of the heat exchanger and heat exchange when the amount of water supplied to the heat exchanger decreases or water is shut off. The temperature of the heat exchanger is lowered by injecting air or nitrogen gas into the water channel of the vessel.

  As a result, in addition to the effect of the protection method of the cogeneration system of the first embodiment, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or shut down, the water in the water channel of the heat exchanger In order to drain the water from the drainage switching valve 29, the hot water stays in the water passage 28 of the heat exchanger 7, is heated by the exhaust gas to become water vapor, expands, and the pressure rises. There is no fear. Further, air or nitrogen gas ejected from the cooling air supply source 22 is injected from the intake air switching valve 27 into the water passage 28 of the heat exchanger 7 to cool the water passage 28, so that the temperature of the heat exchanger 7 is increased. Can be prevented, and damage to the heat exchanger 7 can be prevented.

[Embodiment 1]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the invention will be described based on examples with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a protection method for a cogeneration system according to Embodiment 1 of the present invention. In the figure, a cooling air supply source 22 provided with a compressor or a blower ejects cooling air. The cooling air supply source 22 is connected to the exhaust pipe 6 by a thin tube 23, and a cooling air valve 24 and a cooling air flow rate regulator 26 are provided at a position away from the exhaust pipe 6 of the thin tube 23 if necessary. ing. Further, in order to reduce the heat radiation of the exhaust pipe 6, the fuel cell 5 and the heat exchanger 7 are provided close to each other, and a heat insulating material is wound around the exhaust pipe 6 and the thin tube 23.

  The water cutoff detection sensor 9 detects that the amount of water supplied by the cold water supply source 20 has dropped or has been cut off, and outputs a water cutoff detection signal S1 to the cooling air supply source 22 and the cooling air valve 24. The cooling air valve 24 receives the water cutoff detection signal S1 and opens the valve. The cooling air supply source 22 inputs the water break detection signal S1 and jets air to the narrow tube 23. For the other functions, the same functions as those of the prior art shown in FIG.

  The operation will be described below. When the amount of water supplied from the chilled water supply source 20 to the heat exchanger 7 decreases or water is cut off, the water cut detection sensor 9 detects this and a water cut detection signal is sent to the cooling air supply source 22 and the cooling air valve 24. S1 is output. The cooling air valve 24 receives the water cutoff detection signal S1 and opens the valve. The cooling air supply source 22 receives the water cutoff detection signal S1 and ejects air. As a result, the air ejected from the cooling air supply source 22 is mixed into the exhaust pipe 6 through the narrow tube 23. The operation of other functions is the same as the operation of the functions denoted by the same reference numerals in the prior art shown in FIG.

  As a result, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or shut down, the temperature of the exhaust gas supplied to the heat exchanger 7 by the cooling air can be lowered. The heat exchanger 7 is not damaged due to an abnormal rise in temperature or an abnormal rise in pressure due to vaporization of the internal water. Further, since the exhaust gas switching valve 8 and the bypass pipe 10 as in the prior art are not provided, the heat of the exhaust gas does not escape to these devices, and sufficient heat is supplied to the heat exchanger 7, so that energy efficiency is improved. Can be increased. Further, since there is no need to provide a large exhaust gas switching valve 8 as in the prior art, the system does not increase in size.

  When the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or shut down, the flow rate of the cooling air supplied from the cooling air supply source 22 is changed to the cooling air flow rate regulator 26. It may be controlled so as to increase gradually. In this case, rapid cooling of the heat exchanger 7 can be avoided, and the heat exchanger 7 can be more reliably protected.

[Modification of Embodiment 1]
FIG. 2 is a diagram showing a configuration of a modified example of the cogeneration system protection method according to the first embodiment of the present invention. The case where the cooling air is supplied from the operating air supply source 2 is shown. In the figure, the cooling air valve 24 and the cooling air flow rate regulator 26 shown in FIG. 1 are provided in a fuel supply unit 25. The cooling air valve 24 receives the water cutoff detection signal S1 from the water cutoff detection sensor 9 and opens the valve. For the other functions, the same functions as those of the first embodiment shown in FIG.

  The operation will be described below. Fuel air and fuel cell cooling air are supplied from the operating air supply source 2 with the cooling air valve 24 closed during normal operation. When the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or water is cut off, the cooling air valve 24 inputs the water cut detection signal S1 from the water cut detection sensor 9, and the valve is opened. Become. As a result, the air is supplied from the operating air supply source 2 through the cooling air valve 24 and enters the exhaust pipe 6 through the narrow tube 23. Therefore, since the cooling air can be mixed into the exhaust pipe 6 by one large-capacity operating air supply source 2, it is supplied to the heat exchanger 7 with a compact configuration and the temperature of the exhaust gas is lowered. The temperature of the heat exchanger 7 does not rise abnormally and is not damaged.

[Embodiment 2]
FIG. 3 is a diagram showing the configuration of the cogeneration system protection method according to the second embodiment of the present invention. In the figure, a drainage switching valve 29 is provided in a pipe between the water break detection sensor 9 and the heat exchanger 7 and is usually connected to a flow path for supplying cold water from the cold water supply source 20 to the heat exchanger 7. Has been. And when the water stop detection signal S1 from the water stop detection sensor 9 is inputted, the drainage switching valve 29 is switched so as to connect the water passage 28 and the drainage side of the heat exchanger 7. The intake air switching valve 27 is provided in a pipe between the heat exchanger 7 and the hot water storage tank 21 and is connected to the cooling air supply source 22 and normally supplies hot water from the heat exchanger 7 to the hot water storage tank 21. It is connected to the flow path. When the water break detection signal S1 from the water break detection sensor 9 is input, the intake air switching valve 27 is switched so as to connect the water passage 28 of the heat exchanger 7 and the cooling air supply source 22. Further, the water cutoff detection sensor 9 detects that the amount of water supplied from the cold water supply source 20 has dropped or has been cut off, and sends a water cutoff detection signal S1 to the cooling air supply source 22, the intake air switching valve 27 and the drainage switching valve 29. Is output. For the other functions, the same functions as those of the first embodiment shown in FIG.

  The operation will be described below. When the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or water is cut off, the water cut detection sensor 9 detects this and detects the cooling air supply source 22, the intake air switching valve 27, and the drainage switching valve 29. A water cutoff detection signal S1 is output. The drainage switching valve 29 receives the water cutoff detection signal S1 and switches so that the water passage 28 and the drainage side of the heat exchanger 7 are connected. The intake air switching valve 27 also receives the water cutoff detection signal S1 and switches the water path 28 of the heat exchanger 7 and the cooling air supply source 22 to be connected. In addition, the cooling air supply source 22 receives the water cutoff detection signal S1 and ejects air. As a result, the hot water in the water channel 28 of the heat exchanger 7 is drained from the drain switching valve 29, and the air ejected from the cooling air supply source 22 is jetted from the intake switching valve 27 into the water channel 28 of the heat exchanger 7. The The other operations are the same as those of the first embodiment shown in FIG.

  As a result, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 decreases or water is cut off, hot water is accumulated in the water passage 28 of the heat exchanger 7 in order to drain water from the drainage switching valve 29. It is heated with exhaust gas to become water vapor, and it does not expand to increase the pressure. Further, the air ejected from the cooling air supply source 22 is injected from the intake air switching valve 27 into the water passage 28 of the heat exchanger 7 to cool the water passage 28, so that the temperature of the heat exchanger 7 rises. In addition, it is possible to prevent the heat exchanger 7 from being damaged due to an abnormal increase in pressure due to vaporization of the internal water.

[Embodiment 3]
FIG. 4 is a diagram showing the configuration of the cogeneration system protection method according to the third embodiment of the present invention. In the figure, in addition to the function of the first embodiment shown in FIG. 1, a drainage switching valve 29 is provided in a pipe between the heat exchanger 7 and the water breakage detection sensor 9, and the water breakage detection sensor 9 is The water cutoff detection signal S1 to be output is input, the drainage switching valve 29 is switched so as to connect the water passage 28 and the drainage side of the heat exchanger 7, and the hot water in the water passage 28 of the heat exchanger 7 is drained. Further, the water cutoff detection sensor 9 detects that the amount of water supplied from the cold water supply source 20 has dropped or has been cut off, and sends a water cutoff detection signal to the cooling air supply source 22, the cooling air valve 24 and the drainage switching valve 29. S1 is output. For the other functions, the same functions as those of the first embodiment shown in FIG.

  The operation will be described below. When the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or water is cut off, the water cut detection sensor 9 detects this and detects the cooling air supply source 22, the cooling air valve 24, and the drainage switching valve. 29 outputs a water stoppage detection signal S1. The cooling air valve 24 receives the water cutoff detection signal S1 and opens the valve. The cooling air supply source 22 receives the water cutoff detection signal S1 and ejects air. As a result, the air ejected from the cooling air supply source 22 is mixed into the exhaust pipe 6 through the narrow tube 23. Further, the drainage switching valve 29 receives the water cutoff detection signal S <b> 1, switches to connect the water passage 28 of the heat exchanger 7 and the drainage side, and drains hot water in the water passage 28 of the heat exchanger 7. The other operations are the same as those of the first embodiment shown in FIG.

  As a result, in addition to the effect exhibited by the protection method of the cogeneration system of the first embodiment, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 decreases or water is cut off, In order to drain the water, water stays in the water channel 28 of the heat exchanger 7 and is heated by the exhaust gas to become water vapor, which does not expand and increase in pressure. Therefore, damage to the heat exchanger 7 can be prevented.

[Embodiment 4]
FIG. 5 is a diagram showing a configuration of a protection method for a cogeneration system according to Embodiment 4 of the present invention. In the figure, in addition to the function of the first embodiment shown in FIG. 1, the drainage switching valve 29 is provided in a pipe between the heat exchanger 7 and the water break detection sensor 9. The water cutoff detection signal S1 to be output is input, and the drainage switching valve 29 is switched so as to connect the water passage 28 and the drainage side of the heat exchanger 7 to drain the hot water in the water passage 28 of the heat exchanger 7. The intake air switching valve 27 is provided in a pipe between the heat exchanger 7 and the hot water tank 21 and is connected to the cooling air supply source 22. Further, a water break detection signal S1 output from the water break detection sensor 9 is input, and the water path 28 of the heat exchanger 7 and the cooling air supply source 22 are switched to be connected, and the cooling air is switched to the water path of the heat exchanger 7. 28 is injected. In addition, the water cutoff detection sensor 9 detects that the amount of water supplied from the cold water supply source 20 has decreased or has stopped, and has supplied a cooling air supply source 22, a cooling air valve 24, an intake air switching valve 27, and a drainage switching valve. 29 outputs a water stoppage detection signal S1. For the other functions, the same functions as those of the first embodiment shown in FIG.

  The operation will be described below. When the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 decreases or water is cut off, the water cut detection sensor 9 detects this and detects the cooling air supply source 22, the cooling air valve 24, and the intake air switching valve. 27 and the drainage switching valve 29 are supplied with a water outage detection signal S1. The cooling air valve 24 receives the water cutoff detection signal S1 and opens the valve. The drainage switching valve 29 receives the water cutoff detection signal S1 and switches so that the water passage 28 and the drainage side of the heat exchanger 7 are connected. The intake air switching valve 27 receives the water cutoff detection signal S1 and switches the water path 28 of the heat exchanger 7 and the cooling air supply source 22 to be connected. In addition, the cooling air supply source 22 receives the water cutoff detection signal S1 and ejects air. As a result, the air ejected from the cooling air supply source 22 is mixed into the exhaust pipe 6 through the narrow tube 23. Further, water in the water passage 28 of the heat exchanger 7 is drained from the drainage switching valve 29, and air ejected from the cooling air supply source 22 is jetted from the intake air switching valve 27 into the water passage 28 of the heat exchanger 7. . The other operations are the same as those of the first embodiment shown in FIG.

  As a result, in addition to the effect exhibited by the protection method of the cogeneration system of the first embodiment, when the amount of water supplied from the cold water supply source 20 to the heat exchanger 7 is reduced or water is cut off, water is discharged from the drainage switching valve 29. In order to drain water, hot water stays in the water passage 28 of the heat exchanger 7 and is heated by the exhaust gas to become water vapor, which does not expand and increase in pressure. Furthermore, since the air ejected from the cooling air supply source 22 is injected from the intake air switching valve 27 into the water passage 28 of the heat exchanger 7 to cool the water passage 28, the temperature of the heat exchanger 7 rises. This can prevent the heat exchanger 7 from being damaged.

  Normally, nitrogen gas is supplied to the fuel cell when the fuel cell is started and stopped. Therefore, this nitrogen gas cylinder may be used in place of the cooling air supply source 22 described above to mix nitrogen gas into the exhaust pipe 6 and reduce the temperature of the exhaust gas supplied to the heat exchanger 7.

The method for protecting a cogeneration system according to the present invention has been described for the case where a fuel cell is used as a power generator / heater. However, the method can also be applied to a method for protecting a cogeneration system using a power generator / heater such as a gas turbine or a gas engine. Can do.

It is a figure which shows the structure of the protection method of the cogeneration system of Embodiment 1 of this invention. It is a figure which shows the structure of the modification of the protection method of the cogeneration system of Embodiment 1 of this invention. It is a figure which shows the structure of the protection method of the cogeneration system of Embodiment 2 of this invention. It is a figure which shows the structure of the protection method of the cogeneration system of Embodiment 3 of this invention. It is a figure which shows the structure of the protection method of the cogeneration system of Embodiment 4 of this invention. It is a figure which shows the structure of the protection method of the prior art cogeneration system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel supply unit 2 Air supply source for operation 3 Gas supply source 4 Pure water supply source 5 Fuel cell 6 Exhaust piping 7 Heat exchanger 8 Exhaust gas switching valve 9 Water shutoff detection sensor 10 Bypass piping 11 Fuel air valve 12 Fuel air Flow regulator 13 Fuel cell cooling air valve 14 Fuel cell cooling flow regulator 15 Gas valve 16 Gas flow regulator 17 Pure water valve 18 Pure water flow meter 20 Cold water supply source 21 Hot water tank 22 Cooling air supply source 23 Narrow tube 24 Cooling air valve 25 Fuel supply unit 26 Cooling air flow regulator 27 Intake switching valve 28 Water channel 29 Drain switching valve S1 Water outage detection signal

Claims (4)

Electricity and high-temperature exhaust gas are generated by a power generator such as a fuel cell, a gas turbine, or a gas engine, and the electricity is supplied to a load or an electric power system through an electric circuit, and the exhaust gas is supplied to a heat exchanger. In the protection method of a cogeneration system that supplies hot water by supplying water to the water channel of this heat exchanger,
When the amount of water supplied to the heat exchanger is reduced or shut down, air or nitrogen gas is mixed into the exhaust gas to reduce the temperature, thereby preventing the heat exchanger from becoming abnormally high temperature. Cogeneration system protection method. Electricity and high-temperature exhaust gas are generated by a power generator such as a fuel cell, a gas turbine, or a gas engine, and the electricity is supplied to a load or an electric power system through an electric circuit, and the exhaust gas is supplied to a heat exchanger. In the protection method of the cogeneration system that supplies hot water by supplying water to the water channel of this heat exchanger and changing to hot water,
When the amount of water supplied to the heat exchanger is reduced or water is cut off, water is drained from the water channel of the heat exchanger, and air or nitrogen gas is injected into the water channel of the heat exchanger so that the temperature of the heat exchanger The cogeneration system protection method is characterized in that the heat exchanger is prevented from becoming abnormally high temperature and pressure by lowering the temperature.   2. The method of protecting a cogeneration system according to claim 1, wherein when the amount of water supplied to the heat exchanger is reduced or water is cut off, water is drained from a water channel of the heat exchanger. When the amount of water supplied to the heat exchanger is reduced or water is cut off, water is drained from the water channel of the heat exchanger, and air or nitrogen gas is injected into the water channel of the heat exchanger so that the temperature of the heat exchanger The cogeneration system protection method according to claim 1, wherein the cogeneration system is reduced.

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