JP2010165640A - Fuel cell unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell unit capable of continuing operation of a fuel cell while preventing inverse tide into a commercial power supply in a simple structure. <P>SOLUTION: The fuel cell unit 1 includes a fuel cell 13 generating power to be supplied to a power load 90 in liaison with a commercial power supply 80, a surplus power consumption device 14 consuming surplus power out of power generated at the fuel cell 13, and a case 16 housing the fuel cell 13 and the surplus power consumption device 14. The surplus power consumption device 14 includes an electric heater 14h radiating heat with the surplus power, and the case 16 has formed an intake port 16a taking in air as well as an exhaust port 16b exhausting air taken in from the intake port 16a, with the surplus power consumption device 14 arranged in the vicinity of the exhaust port 16b. With this arrangement, surplus power generated at the fuel cell 13 can be consumed at the surplus power consumption device 14, on one hand, and heat generated at the electric heater 14h can be promptly exhausted outside the case 16, on the other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell unit, and more particularly to a fuel cell unit capable of continuing the operation of a fuel cell while preventing a reverse power flow to a commercial power source with a simple configuration.

  A fuel cell that uses hydrogen and oxygen to generate electric power through these electrochemical reactions has attracted attention as an environmentally friendly power generator. In general, a fuel cell is connected to a commercial power source, and the power generated by the fuel cell is reduced by a predetermined amount from the power consumption of the power load while supplying a shortage of power from the commercial power source. Is absorbed by commercial power. In addition, because of the characteristics of the fuel cell, it is difficult to change the output suddenly. Therefore, when the power consumption of the power load decreases rapidly, the output of the fuel cell exceeds the power consumption of the power load. It can happen. In view of the fact that there are many electric power companies that do not allow reverse power flow from the viewpoint of stabilization of power supply, surplus power generated in the fuel cell in order to avoid reverse flow of the surplus fuel cell output. There is a technique of providing an electric heater that consumes the heat, converting surplus power into heat with an electric heater, and storing the heat using water as a medium for effective use (see, for example, Patent Document 1).

JP 2008-176944 A (paragraph 0011 and the like)

  However, since the electric heater for preventing a reverse power flow described above is an electric device that comes into contact with water, a structure for reliably performing electric insulation of a portion that comes into contact with water becomes complicated. Further, when the heat storage tank for storing the exhaust heat is no longer capable of storing heat, the operation of the fuel cell cannot be continued.

  An object of the present invention is to provide a fuel cell unit capable of continuing the operation of a fuel cell while preventing a reverse power flow to a commercial power source with a simple configuration.

  In order to achieve the above object, a fuel cell unit according to a first aspect of the present invention is a fuel cell that generates power to be supplied to a power load 90 in conjunction with a commercial power supply 80, for example, as shown in FIG. A surplus power consuming device 14 that consumes surplus power out of the power generated in the fuel cell 13 and having an electric heater 14h that generates heat by surplus power; a fuel cell 13 and surplus power consumption A housing 16 that houses the device 14 and includes a housing 16 formed with an intake port 16a for taking in air and an exhaust port 16b for discharging the air taken in from the intake port 16a; It is disposed in the vicinity of the exhaust port 16b.

  If comprised in this way, the heat which generate | occur | produced with the electric heater can be rapidly discharged | emitted out of a housing | casing, consuming the surplus electric power which generate | occur | produced with the fuel cell with the surplus electric power consumption apparatus, and even if surplus electric power generate | occur | produces, it is simple. With the configuration, it is possible to continue the operation of the fuel cell while preventing a reverse power flow to the commercial power source.

  Further, the fuel cell unit according to the second aspect of the present invention is, for example, as shown in FIG. 1, in the fuel cell unit 1 according to the first aspect of the present invention described above, the surplus power consuming device 14 includes a casing 16. It is configured to include an air flow device 14f that operates with surplus power that discharges the air from the exhaust port 16b.

  With this configuration, the heat generated in the electric heater can be forcibly discharged outside the casing by the air flowing in the air flowing apparatus while consuming surplus power in the air flowing apparatus, and the temperature rise in the casing can be reduced. The reverse power flow to the commercial power supply can be prevented while suppressing.

  Further, the fuel cell unit according to the third aspect of the present invention is, for example, as shown in FIG. 1, in the fuel cell unit 1 according to the second aspect of the present invention, the surplus power is transferred to the electric heater 14h and the air flow device. The surplus power distribution device 18 is distributed to 14f.

  With this configuration, for example, when the amount of surplus power is large and the output of the electric heater is large, the output of the air flow device is also increased. When the amount of surplus power is small and the output of the electric heater is small, the output of the air flow device is also increased. The surplus power can be appropriately distributed according to the amount, such as to reduce, and the fuel cell operation can be continued while preventing the reverse power flow to the commercial power supply while maintaining the temperature inside the housing appropriately Can do.

  According to the present invention, the heat generated by the electric heater can be quickly discharged out of the housing while consuming the surplus power generated in the fuel cell by the surplus power consuming device, and even if surplus power is generated, it is simple. The configuration can prevent reverse power flow to commercial power.

1 is a schematic configuration diagram of a fuel cell unit according to an embodiment of the present invention. It is a flowchart of the reverse power flow avoiding operation of the fuel cell unit according to the embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or similar members are denoted by the same or similar reference numerals, and redundant description is omitted.

  First, a fuel cell unit 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the fuel cell unit 1. The fuel cell unit 1 is configured such that a fuel cell 13, a surplus power consuming device 14 that consumes surplus power out of the power generated in the fuel cell 13, and a control device 15 are accommodated in a casing 16. The casing 16 also houses a raw fuel supply device 11 and a fuel processing device 12. The housing 16 is provided with an air inlet 16a on one side surface which is the lower part when the fuel cell unit 1 is installed. In addition, the casing 16 is provided with an exhaust port 16b on one side surface of a substantially diagonal line of the intake port 16a (where the distance from the intake port 16a is far), which is an upper part when the fuel cell unit 1 is installed. ing.

  The raw material fuel supply device 11 is a device that supplies the raw material fuel m, which is the raw material of the fuel gas g supplied to the fuel cell 13, to the fuel processing device 12. Typically, the raw material fuel m is mainly composed of chain hydrocarbons (including natural gas) such as methane and ethane, or hydrocarbons such as methanol and petroleum products (kerosene, gasoline, naphtha, LPG, etc.). A hydrocarbon-based fuel such as a mixture is used. The raw material fuel supply device 11 includes a desulfurizer that removes sulfur from the raw material fuel m in order to avoid sulfur poisoning of the reforming catalyst of the fuel processing device 12. In addition, the raw fuel supply device 11 includes a blower or a pump for sending the raw fuel m to the fuel processing device 12. The raw material supply apparatus 11 may include a tank that stores the raw material fuel m. When the tank is not provided, the raw material fuel m is introduced from an external storage tank.

  The fuel processing device 12 is a device that introduces a raw material fuel m and reforms it to generate a fuel gas g rich in hydrogen. The fuel gas g rich in hydrogen is a gas containing hydrogen as a main component, and is a gas supplied to the fuel cell 13 containing hydrogen in an amount of 40% by volume or more, typically about 70 to 80% by volume. The hydrogen concentration in the fuel gas g may be 80% by volume or more, that is, it may be a concentration that allows power generation by an electrochemical reaction with oxygen in the oxidant gas when supplied to the fuel cell 13. The fuel processing device 12 introduces the raw material fuel m sent from the raw material fuel supply device 11, adds reforming water as a modifier, and reforms the raw material fuel m to produce the fuel gas g generated. The battery 13 is configured to be supplied. The fuel processing device 12 includes a reforming catalyst packed bed and is configured to promote a steam reforming reaction of the raw material fuel m. Since the steam reforming reaction is an endothermic reaction, the fuel processor 12 has a combustion section for supplying reforming heat necessary for reforming. The combustion section has a burner, and is configured so as to obtain reformed heat by introducing and burning combustible fuel and air. As the combustible fuel, an anode off-gas containing hydrogen discharged from the raw fuel m and the fuel cell 13 is used.

  The fuel cell 13 is a device that introduces a fuel gas g rich in hydrogen and an oxidant gas containing oxygen and generates electric power by an electrochemical reaction between hydrogen in the fuel gas g and oxygen in the oxidant gas. The fuel cell 13 is typically a polymer electrolyte fuel cell. Although the fuel cell 13 is simply shown in the figure, in practice, a single cell is formed by sandwiching a solid polymer film as an electrolyte between a fuel electrode and an air electrode, and this single layer cell. Are laminated by a plurality of cooling units. In the fuel cell 13, hydrogen in the fuel gas g supplied to the fuel electrode is decomposed into hydrogen ions and electrons, and the hydrogen ions pass through the solid polymer film and move to the air electrode, while the electrons move to the fuel electrode and air. It moves to the air electrode through a conducting wire connecting to the electrode, reacts with oxygen in the oxidant gas supplied to the air electrode to generate water, and generates heat during this reaction. In this reaction, DC power can be taken out when electrons pass through the conducting wire. The reacted fuel gas g is discharged from the fuel electrode as an anode off gas, and the reacted oxidant gas is discharged from the air electrode as a cathode off gas together with the generated moisture. As described above, the anode off-gas discharged from the fuel electrode is used as a combustible fuel combusted in the combustion unit of the fuel processing device 12.

  The fuel electrode of the fuel cell 13 and the fuel processing device 12 are connected by a flow path in which a control valve 19 is disposed, and the fuel gas g generated by the fuel processing device 12 is supplied to the fuel electrode of the fuel cell 13. It is configured to be able to. The control valve 19 is typically an electric two-way valve. A signal cable is laid between the control valve 19 and the control device 15, and the control valve 19 is configured to receive a signal from the control device 15 and adjust the opening of the valve. . The fuel cell 13 is connected to an output cable 33 that outputs generated power toward the power load 90. The power load 90 is an external load installed outside the fuel cell unit 1. The output cable 33 is typically provided with a power conditioner (not shown) that converts DC power into AC power. A load cable 39 connected to the power load 90 is connected to the other end of the output cable 33. A commercial cable 38 that propagates the power supplied from the commercial power supply 80 toward the power load 90 is connected to a connection portion between the output cable 33 and the load cable 39. The commercial cable 38 is provided with a wattmeter 38 </ b> M that detects the amount of power supplied from the commercial power supply 80. The wattmeter 38M is connected to the control device 15 via a signal cable, and is configured to be able to transmit the power value detected by the wattmeter 38M to the control device 15 as a signal.

  The surplus power consuming device 14 is a device that can consume the surplus power when the power generated in the fuel cell 13 becomes surplus. From the viewpoint of preventing the power generated in the fuel cell 13 from flowing backward to the commercial power source 80, it is preferable that the power load 90 is supplied with at least a certain minimum power from the commercial power source 80 out of the total power consumption. The surplus power here is the remaining power after subtracting the power obtained by subtracting the minimum power from the total power consumption of the power load 90 from the power generated in the fuel cell 13. The minimum power may be 100 w, for example, but may be 0 w. The surplus power consuming device 14 has an electric heater 14h that operates with the power generated by the fuel cell 13 and a fan 14f as an air flow device.

  The electric heater 14h is connected to a power distributor 18 as a surplus power distribution device via a heater cable 34h, and the fan 14f is connected to the power distributor 18 via a fan cable 34f. The power distributor 18 is connected to the output cable 33 via a surplus cable 34. The power distributor 18 is a device that distributes the power supplied via the surplus cable 34 to at least the heater cable 34h and the fan cable 34f. The power distributor 18 is connected to the control device 15 through a signal cable, and is configured so that the ratio of the power distributed to the heater cable 34h and the fan cable 34f can be changed according to a command signal from the control device 15. The surplus cable 34 is typically connected to the output cable 33 on the fuel cell 13 side of a power conditioner (not shown), and the electric heater 14h and the fan 14f are configured to operate with DC power. The surplus cable 34 may be connected to the output cable 33 closer to the power load 90 than the power conditioner (not shown), and the electric heater 14h and the fan 14f may be configured to operate with AC power.

  The surplus power consumption device 14 is disposed in the vicinity of the exhaust port 16b. Here, the vicinity of the exhaust port 16b refers to the casing 16 as appropriate so that the heat generated from the surplus power consuming device 14 can be maintained in the casing 16 at a temperature that does not affect other accommodated devices. It is a position where it can be discharged outside. The surplus power consumption device 14 is typically disposed at a position closer to the exhaust port 16b than other devices (for example, the control device 15 and the like) that require cooling. Further, in the present embodiment, an electric heater 14h is installed in the immediate vicinity of the exhaust port 16b, and a fan 14f is installed on the inner side adjacent to the electric heater 14h. In other words, the electric heater 14h is provided at a position sandwiched between the exhaust port 16b and the fan 14f. Further, the fan 14f is installed in such a direction that the air flow when it operates is directed toward the exhaust port 16b. With this configuration, the heat generated by the electric heater 14 h can be quickly discharged out of the casing 16 without remaining in the casing 16. Further, when the fan 14f is operated, outside air is introduced from the intake port 16a, and an air flow is generated from the intake port 16a to the exhaust port 16b. At this time, the intake port 16a and the exhaust port 16b are substantially diagonal. By being provided, it is configured to prevent the outside air introduced into the fuel cell unit 1 from being short-circuited. The fan 14f may be disposed between the electric heater 14h and the exhaust port 16b (the electric heater 14h may be disposed on the suction side of the fan 14f). In addition, a hood (not shown) may be provided around the electric heater 14h so that all the air that has passed through the electric heater 14h is guided to the exhaust port 16b. In this way, the heat generated by the electric heater 14h can be reliably discharged out of the housing 16.

  The control device 15 is a device that controls the operation of the fuel cell unit 1. The control device 15 is connected to the control valve 19 and an oxidant gas blower (not shown) that supplies oxidant gas to the fuel cell 13 through signal cables, respectively, and adjusts the opening of the control valve 19 to the fuel cell 13. By controlling the flow rate of the oxidant gas introduced into the fuel cell 13 by controlling the flow rate of the introduced fuel gas g and adjusting the rotational speed of the oxidant gas blower (not shown), power generation in the fuel cell 13 is achieved. The power (output) can be controlled. The control device 15 is connected to the raw material fuel supply device 11 through a signal cable, and is configured to be able to adjust the flow rate of the raw material fuel m supplied from the raw material fuel supply device 11 to the fuel processing device 12. ing. The control device 15 is connected to the wattmeter 38M via a signal cable, and is configured to receive a value detected by the wattmeter 38M as a signal.

  Further, the control device 15 is connected to the power distributor 18 via a signal cable, and is configured to be able to adjust the power supplied to the electric heater 14h and the fan 14f. Typically, based on the value received from the wattmeter 38M, the power distributor 18 is controlled so that the power generated by the surplus fuel cell 13 is appropriately distributed to the electric heater 14h and the fan 14f. The At this time, it is preferable that the control device 15 controls the power distributor 18 so that the power supplied to the electric heater 14h and the fan 14f is apportioned at a predetermined ratio. The predetermined ratio is typically such a ratio that the heat generated in the electric heater 14h and the air volume of the fan 14f that can discharge the heat to the outside of the housing 16 are balanced.

  With continued reference to FIG. 1, the operation of the fuel cell unit 1 will be described. The raw material fuel supply device 11 desulfurizes the raw material fuel m stored in an internal or external tank with a desulfurizer, and then pumps it to the fuel processing device 12 with a blower or a pump. In the fuel processing device 12, the supplied raw material fuel m and reforming water introduced separately are guided to the reforming catalyst packed bed, and reforming heat is obtained from the combustion section to perform a steam reforming reaction. The fuel gas g rich in hydrogen produced by the fuel processor 12 is supplied to the fuel cell 13. The fuel cell 13 introduces the fuel gas g and air as the oxidant gas, and generates power by an electrochemical reaction between hydrogen in the fuel gas g and oxygen in the oxidant gas. In addition, heat is generated by the electrochemical reaction, and moisture is generated. Specifically, electric power can be obtained when electrons on the fuel electrode side move to the air electrode side through the external electric circuit. Further, hydrogen ions on the fuel electrode side pass through the solid polymer film and move to the air electrode side, and combine with oxygen to generate moisture.

  The DC power generated in the fuel cell 13 is converted into AC power by a power conditioner (not shown), and then supplied to the power load 90 via the output cable 33 and the load cable 39. On the other hand, the power supplied from the commercial power supply 80 is also supplied to the power load 90 via the commercial cable 38 and the load cable 39. In other words, the power generated by the fuel cell 13 and the power supplied from the commercial power source 80 are transmitted to the power load 90. Typically, first, all of the power that can be supplied out of the power generated in the fuel cell 13 excluding the amount used for the operation of the auxiliary equipment of the fuel cell unit 1 is supplied to the power load 90, and the shortage is reduced. Supplemented with electric power supplied from the commercial power source 80. However, from the viewpoint of avoiding the reverse flow of the electric power generated in the fuel cell 13 to the commercial power source 80, the control device 15 receives the value detected by the wattmeter 38M and sends a predetermined value from the commercial power source 80 to the power load 90. When the value detected by the wattmeter 38M becomes less than the minimum power, the opening degree of the control valve 19 and the oxidant gas blower are set so that the power becomes equal to or higher than the minimum power. The output of the fuel cell 13 is controlled by adjusting the rotational speed (not shown). At this time, since it is difficult for the fuel cell 13 to change its output suddenly due to its characteristics, when the power consumption of the power load 90 decreases rapidly, the output of the fuel cell 13 does not fall in time, and the commercial power source 80 is turned on. Surplus power that can flow backward will be generated. Even in such a situation, in order to avoid reverse power flow, the fuel cell unit 1 operates as follows.

  FIG. 2 is a flowchart of the reverse power flow avoiding operation of the fuel cell unit 1. As described above, while controlling the output of the fuel cell 13 so that the value detected by the wattmeter 38M is equal to or higher than the minimum power, the control device 15 causes the value detected by the wattmeter 38M to be less than the minimum power. It is determined whether or not (ST1). If it is not less than the minimum power, the process (ST1) of determining whether or not the value detected by the wattmeter 38M is less than the minimum power is continued. On the other hand, when the value detected by the wattmeter 38M becomes less than the minimum power due to a cause such as a sudden decrease in the power consumption of the power load 90, the control device 15 transfers the surplus power via the power distributor 18 to the electric heater. 14h and the fan 14f are supplied (ST2). As a result, surplus power is consumed by the electric heater 14h without flowing backward to the commercial power source 80 and converted into heat, and is consumed by the fan 14f to become blowing energy. Furthermore, since surplus power is supplied to the electric heater 14h and the fan 14f, heat generated in the electric heater 14h is discharged from the exhaust port 16b to the outside of the casing 16 by the airflow generated in the fan 14f. It can be avoided that the inside becomes high temperature and adversely affects other devices (for example, the control device 15).

  When surplus power is supplied to the electric heater 14h and the fan 14f (ST2), the control device 15 determines whether or not the value detected by the wattmeter 38M is equal to or higher than the minimum power (ST3). If the electric power does not exceed the minimum electric power, surplus electric power is continuously supplied to the electric heater 14h and the fan 14f (ST2). On the other hand, when the value detected by the wattmeter 38M becomes equal to or greater than the minimum power, the control device 15 cuts off the power supply to the electric heater 14h and the fan 14f via the power distributor 18 (ST4). From the viewpoint of suppressing the temperature rise in the housing 16 during operation of the fuel cell unit 1, during operation of the fuel cell unit 1 even after the value detected by the wattmeter 38M becomes equal to or higher than the minimum power. The fan 14f may be operated with an air volume that can suppress the temperature rise in the housing 16. When the energization of the electric heater 14h and the fan 14f is cut off (the power supplied to the fan 14f may be reduced without being cut off), it is checked again whether the value detected by the wattmeter 38M has become less than the minimum electric power. Returning to the determination step (ST1), the above-described flow is repeated thereafter.

  As described above, the fuel cell unit 1 according to the present embodiment exhausts and wastes the heat generated by consuming the surplus power without storing it so that it can be used later. There is a part. As described above, the fuel cell unit 1 is controlled so that the value detected by the wattmeter 38M maintains the minimum power or more, and in recent years, the control device 15 has a learning function, so It is possible to be controlled to operate according to the operation plan based on it, and there are fewer scenes where surplus power is generated, and even if surplus power is generated, the surplus power disappears relatively early Yes. In view of such circumstances, the fuel cell unit 1 according to the present embodiment is configured to further reduce the possibility of reverse flow even if energy is somewhat wasted. Further, by converting the surplus power into heat and discharging it out of the housing 16 by air conveyance, the electric heater 14h has no part in contact with water, so the structure is not complicated, and the heat storage tank for storing the exhaust heat can no longer store heat. There is an advantage that the operation of the fuel cell 13 can be continued even in the state.

  In the above description, the fuel cell 13 is a solid polymer fuel cell, but may be a fuel cell other than a solid polymer fuel cell such as a phosphoric acid fuel cell. However, the polymer electrolyte fuel cell can be operated at a relatively low temperature and can be downsized, so that it is suitable for installation in a general household.

DESCRIPTION OF SYMBOLS 1 Fuel cell unit 13 Fuel cell 14 Surplus power consumption apparatus 14f Fan (air flow apparatus)
14h Electric heater 15 Control device 16 Housing 16a Intake port 16b Exhaust port 18 Power distributor (surplus power distribution device)
80 Commercial power supply 90 Power load

Claims (3)

A fuel cell that generates power to be connected to a commercial power source and supplied to an electric load;
A surplus power consuming device that consumes surplus power out of the power generated in the fuel cell, the surplus power consuming device having an electric heater that generates heat by the surplus power;
A housing for housing the fuel cell and the surplus power consuming device, wherein the housing is formed with an intake port for taking in air and an exhaust port for discharging air taken in from the intake port;
The surplus power consuming device is disposed in the vicinity of the exhaust port;
Fuel cell unit. The surplus power consuming device is configured to include an air flow device that operates with the surplus power that discharges air in the housing from the exhaust port;
The fuel cell unit according to claim 1. A surplus power distribution device that apportions the surplus power to the electric heater and the air flow device;
The fuel cell unit according to claim 2.

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