JP5153243B2 - Fuel cell device - Google Patents

Description

  The present invention relates to a fuel cell device including a fuel cell and a fuel gas supply device for supplying fuel gas to the fuel cell.

  In recent years, as next-generation energy, a fuel cell module containing a plurality of fuel cells (cells) capable of obtaining electric power using hydrogen gas and oxygen-containing gas (usually air), and supplied to the fuel cell Various fuel cell devices in which a reformer for generating hydrogen to be produced and auxiliary equipment such as a fuel supply device for supplying fuel gas (hydrocarbon gas) to the reformer are housed in an outer case Proposed.

  Here, for example, when the fuel cell is a solid oxide fuel cell, it is known to use a hydrocarbon gas such as city gas as the fuel gas, and supply hydrogen generated from the hydrocarbon gas to the fuel cell, While generating electric power by chemically reacting with oxygen, it is possible to obtain a fuel cell system capable of obtaining high energy efficiency as a whole by using the heat energy generated at the same time for hot water supply.

  By the way, when supplying hydrocarbon gas (city gas) to the reformer, the city gas is boosted by rated operation of a booster pump provided in a fuel gas supply pipe connecting the city gas supply source and the fuel cell. It is known that hydrocarbon gas is supplied to the reformer by pumping at a constant pressure (see, for example, Patent Document 1).

FIG. 4 shows a member for supplying hydrocarbon gas to the fuel cell among such conventional fuel cell devices. The hydrocarbon gas includes two solenoid valves, a desulfurizer, a booster gas pump, a buffer, A reformed gas (hydrogen gas), which is supplied to the reformer via the gas flow meter and reformed by the reformer, is supplied to the fuel cell.
JP 2002-358990 A

  By the way, when the fuel cell is a solid oxide fuel cell, for example, when the amount of electric power used is low such as at night, the hydrocarbon gas is supplied at a pressure lower than the original pressure of the hydrocarbon gas such as city gas. May be able to cover enough usage. Here, in the fuel cell device described above, in order to control the flow rate of the hydrocarbon gas to be supplied, it is conceivable to stop the pressurization gas pump. In this case, the original pressure of the hydrocarbon gas and the atmospheric pressure The flow due to the pressure difference became the minimum flow rate, and flow control below that was impossible. As a result, while supplying more hydrocarbon gas than necessary, there was a problem that the amount of power generation became very small and the power generation efficiency deteriorated.

  Therefore, the present applicant, as a fuel gas supply device for supplying hydrogen to the fuel cell first, a reformer for generating hydrogen from hydrocarbon gas, a desulfurizer for removing sulfur in the hydrocarbon gas, A pump for supplying the desulfurized hydrocarbon gas to the reformer and a supply pressure regulator for lowering the supply pressure of the hydrocarbon gas to the reformer below the original pressure of the hydrocarbon gas are provided. A fuel cell device provided on the downstream side of the regulator has been proposed (Japanese Patent Application No. 2007-45613).

  With such a fuel cell device, the supply pressure of hydrocarbon gas can be adjusted, and when the amount of power used at night is low, hydrocarbon gas at a low flow rate can be supplied, improving power generation efficiency. We were able to.

  However, in the fuel cell device described above, for example, when a desulfurizer formed by filling a desulfurization catalyst in a cylindrical container or the like is replaced with the entire cylindrical container as the desulfurization catalyst deteriorates, the desulfurizer is reconnected. In this case, it may be difficult to confirm whether hydrocarbon gas has leaked from the joint between the desulfurizer and the fuel gas supply pipe.

  SUMMARY OF THE INVENTION Therefore, the present invention provides a fuel cell device that can supply an optimal flow rate of hydrocarbon gas to the fuel cell and can check whether or not the hydrocarbon gas has leaked when the desulfurizer is replaced. With the goal.

The fuel cell device of the present invention is a fuel cell device comprising a fuel cell module containing a fuel cell and a fuel gas supply device for supplying hydrogen to the fuel cell module, wherein the fuel gas supply The apparatus includes a desulfurizer for removing sulfur in a hydrocarbon gas supplied from a hydrocarbon gas supplier, a gas flow meter for measuring a flow rate of the desulfurized hydrocarbon gas, and the desulfurized gas A gas pump for pumping hydrocarbon gas, a relief valve or a pressure reducing valve capable of lowering the supply pressure of the pumped hydrocarbon gas below the original pressure of the hydrocarbon gas supply source, and the supply pressure are adjusted and a reformer for reforming the hydrogen the hydrocarbon gas, constituted by connecting in the fuel gas supply pipe in this order, based on the flow rate of the hydrocarbon gas, wherein the gas flow meter which is desulfurized measured And a control unit for adjusting the flow rate of the pumped hydrocarbon gas by controlling the operation of the gas pump, wherein the relief valve or the pressure reducing valve is configured so that the pumped hydrocarbon gas is It opens according to the pressure applied with respect to the relief valve or the said pressure reduction valve, It is characterized by the above-mentioned.

  In such a fuel cell device, for example, when supplying a hydrocarbon gas such as city gas or propane gas to the fuel cell module, a supply pressure regulator is provided to supply the hydrocarbon gas to the reformer. The pressure can be lowered below the original pressure of the hydrocarbon gas supply source. As a result, the hydrocarbon gas from which sulfur has been removed by the desulfurizer can be supplied to the reformer at a low flow rate. Can be improved.

  Further, the fuel gas supply device was pumped by a desulfurizer for removing sulfur in the hydrocarbon gas supplied from the hydrocarbon gas supplier, a gas pump for pumping the desulfurized hydrocarbon gas, and A fuel gas is provided with a supply pressure regulator capable of lowering the hydrocarbon gas below the original pressure of the hydrocarbon gas supply source, and a reformer for reforming the hydrocarbon gas with the adjusted supply pressure into hydrogen. Since the supply pipes are connected in this order, the hydrocarbon gas is supplied to the desulfurizer while maintaining the original pressure, and the hydrocarbon gas from which sulfur has been removed by the desulfurizer is supplied to the reformer by the gas pump. As a result, negative pressure is suppressed at the site where the desulfurizer is arranged. For example, a desulfurizer filled with a desulfurization catalyst inside the container is replaced with the container as the desulfurization catalyst deteriorates. In this case, when the desulfurizer is reconnected, it is possible to confirm whether hydrocarbon gas has leaked from the joint between the desulfurizer and the fuel gas supply pipe.

Further , since the supply pressure regulator is a relief valve or a pressure reducing valve, the supply pressure of the hydrocarbon gas to the reformer can be made lower than the original pressure of the supply source of the hydrocarbon gas. Gas can be supplied at a low flow rate.

In addition , it is equipped with a gas flow meter for measuring the flow rate of hydrocarbon gas and is provided in a fuel gas supply pipe connecting the desulfurizer and the gas pump. It is possible to more accurately measure the flow rate of the hydrocarbon gas supplied to the reformer.

  In the fuel cell device of the present invention, the fuel cell is preferably a solid oxide fuel cell.

  In such a fuel cell device, since it is possible to supply a hydrocarbon gas such as city gas at a low flow rate, it is particularly useful in a solid oxide fuel cell with high power generation efficiency, and power used at night and the like. In the case where the amount of fuel is small, a low flow rate hydrocarbon gas can sufficiently cover the electric power used, and a fuel cell device with improved power generation efficiency can be obtained.

  The fuel cell device of the present invention can reduce the supply pressure of the hydrocarbon gas to the reformer below the original pressure of the hydrocarbon gas supply source. Can be supplied. Furthermore, when a desulfurizer equipped with a desulfurization catalyst is replaced and reconnected, the presence or absence of hydrocarbon gas leakage from the joint between the desulfurizer and the fuel gas supply pipe can be confirmed. Therefore, a fuel cell device with improved safety can be obtained.

  FIG. 1 is a configuration diagram showing an example of the configuration of the fuel cell device of the present invention. The fuel cell device includes a fuel cell 1 and a fuel gas supply device 11 that supplies hydrogen to the fuel cell 1. In the following drawings, the same number is assigned to the same configuration.

  The fuel gas supply device 11 includes two solenoid valves 7, a desulfurizer 6, a gas flow meter 8, a buffer 9, a gas pump 4, and a supply pressure regulator 5 via a fuel gas supply pipe 12 from the hydrocarbon gas supply side. The reformer 3 is connected in this order.

  The desulfurizer 6 is for removing sulfur contained in the hydrocarbon gas supplied from a hydrocarbon gas supply source, and a container having a desulfurization catalyst inside can be used. Thereby, sulfur which is an impurity of hydrocarbon gas (hereinafter, hydrocarbon gas may be referred to as fuel gas) supplied to the fuel cell can be removed. The gas flow meter 8 is for measuring the flow rate of the desulfurized fuel gas flowing through the fuel gas supply pipe 12. The gas pump 4 pumps the desulfurized fuel gas, the pulsation is suppressed by the buffer 9, and a constant flow rate of fuel gas can be supplied to the reformer 3. Further, the flow rate information of the fuel gas (desulfurized fuel gas) flowing through the fuel gas supply pipe 12 measured by the gas flow meter 8 is transmitted to the control device 10, and the control device 10 measures by the gas flow meter 8. The operation of the gas pump 4 is controlled based on the flow rate of the fuel gas.

  The fuel gas supplied to the reformer 3 by the gas pump 4 is supplied to the reformer 3 after the supply pressure is adjusted by a relief valve which is a supply pressure regulator 5. In the description of FIG. 1, a case where a relief valve is used as the supply pressure regulator 5 is shown. Hereinafter, the supply pressure regulator 5 will be described as the relief valve 5.

  The relief valve 5 is set to open at a pressure larger than the gas pressure on the fuel gas supply side (upstream side). That is, by operating the gas pump 4 and discharging the fuel gas supplied from the fuel gas supply source, a pressure greater than the gas source pressure is applied to the relief valve 5, so that the relief valve 5 is opened and the fuel gas is opened. Will flow. Thereby, fuel gas can be supplied at a low flow rate.

  In addition, when fuel gas is city gas, since the original pressure of city gas is 1.5-3.0 kPa, it can be set as 3.5-6 kPa as the pressure which the relief valve 5 opens, for example. The relief valve 5 can also be controlled by the amount of power generated by the fuel cell. For example, when the amount of power generated by the fuel cell is large, the relief valve 5 is opened so that the required amount of fuel gas is reformed. 3 side can be supplied.

  The gas pump 4 pressurizes the fuel gas supplied from the fuel gas supply source and pumps it to the reformer 3 side, and a diaphragm type gas pump 4 is generally used. However, since this diaphragm pump pumps the fuel gas by the reciprocating motion of the diaphragm in the cylinder, the pulsation is likely to occur.

  Therefore, the pulsation of the fuel gas supplied by the gas pump 4 can be attenuated by providing the buffer 9 that is a space having a constant volume on the upstream side of the gas pump 4. Note that the buffer 9 may have a constant volume space by using a member having a constant volume space, or by thickening a part of the fuel gas supply pipe 12.

  The gas flow meter 8 is for measuring the flow rate of the fuel gas flowing through the fuel gas supply pipe 12. The pulsation of the gas pump 4 is attenuated by the buffer 9 so that the accurate flow rate of the fuel gas can be measured. it can. Therefore, it is preferable to provide the buffer 9 at a position farther than the relief valve 5 in order to suppress the influence of the operation of the relief valve 5. In the fuel cell device shown in FIG. 1, the desulfurizer 6 and the gas pump are provided. 4 is provided in the fuel gas supply pipe 12 connecting the

  The flow rate information of the fuel gas measured by the gas flow meter 8 is transmitted to the control device 10, and the control device 10 controls the gas pump 4 so that the fuel gas amount required for the reforming reaction in the reformer 3 is obtained. Operation is controlled. That is, the amount of fuel gas required by the reformer 3 is compared with the amount of fuel gas flowing through the fuel gas supply pipe 12, and when the amount of fuel gas flowing through the fuel gas supply pipe 12 is small, the fuel gas is supplied by the gas pump 4. The gas pump 4 is controlled so as to increase the amount of the fuel gas. Conversely, when the amount of fuel gas flowing through the fuel gas supply pipe 12 is large, the gas pump 4 is controlled so that the amount of fuel gas supplied by the gas pump 4 decreases.

  Various types of fuel cells are known as the fuel cell 1, but a solid oxide fuel cell can be used to reduce the size of the fuel cell. Thereby, in addition to the fuel cell, auxiliary equipment necessary for the operation of the fuel cell 1 can be reduced in size, and the fuel cell device can be reduced in size. At the same time, it is possible to perform a load following operation that follows a fluctuating load required for a household fuel cell.

  Further, in the present invention, the fuel cell 1 is a solid oxide fuel cell with high power generation efficiency, so that when the power consumption is low at night or the like, the fuel cell 1 can sufficiently cover the power consumption with a low flow rate fuel gas. This is particularly useful in the fuel cell device of the present invention capable of controlling the supply of a low flow rate fuel gas. In the following description, the fuel cell 1 is described as a solid oxide fuel cell 1 and is abbreviated as the fuel cell 1.

  In FIG. 1, the fuel cell 1 is stored in a storage container 2 to form a fuel cell module. In addition, the reformer 3 is stored in the storage container 2 in a state of being disposed above the fuel cell 1. Then, the fuel gas flowing through the fuel gas supply pipe 12 is supplied to the reformer 3.

  The reformer 3 reforms the fuel gas supplied through the fuel gas supply pipe 12 to generate hydrogen, and supplies the generated hydrogen to the fuel cell 1. As the reforming reaction in the reformer 3, any of a partial oxidation reforming method, an autothermal method, and a steam reforming method can be used, and a reforming reaction is performed by combining a plurality of reforming methods. You can also.

  The fuel cell 1 generates power using hydrogen supplied from the reformer 3 and oxygen-containing gas supplied from the outside of the storage container 2. The surplus hydrogen in the power generation burns with the oxygen-containing gas supplied from the outside of the storage container 2 above the fuel cell 1 to cause the reformer 3 disposed above the fuel cell 1 to flow. Heating can be performed, whereby the reforming reaction can be performed efficiently.

  In addition, although the fuel cell of various shapes can be used as the shape of the fuel cell 1, it can be set as the hollow plate type fuel cell 1 when performing the electric power generation of the fuel cell 1 efficiently. As such a hollow plate type fuel cell 1, a fuel electrode support type hollow plate type fuel cell having a fuel electrode on the inside and an oxygen electrode on the outside can be used. Are installed on the manifold and electrically connected in series. The hollow plate type fuel cell 1 has a gas flow path through which hydrogen flows, and hydrogen generated in the reformer 3 is supplied to the fuel cell 1 through a manifold.

  By the way, the desulfurizer in which the desulfurization catalyst is filled inside for removing sulfur contained in the fuel gas by continuously generating power of the fuel cell 1 is periodically replaced as the desulfurization catalyst deteriorates. Etc. need to be maintained.

  Here, when the relief valve 5 used in the present invention is disposed, for example, between the electromagnetic valve 7 and the desulfurizer 6, the gas pressure of the fuel gas supplied to the desulfurizer 6 is higher than the atmospheric pressure. Since it becomes low, the desulfurizer 6 may become a negative pressure.

  In this case, when the desulfurizer 6 is composed of a cylindrical container filled with a desulfurization catalyst, when the desulfurizer 6 is replaced and the desulfurizer 6 is reconnected, the desulfurizer 6 and the fuel gas supply pipe If the joint with the gas pipe 12 is not firmly fastened, air leaks into the fuel gas supply pipe 12 from the joint, so that leakage of the fuel gas from the joint between the desulfurizer 6 and the fuel gas supply pipe 12 is confirmed. May be difficult. In addition, when the desulfurizer 6 and the fuel gas supply pipe 12 are not firmly connected, air enters from the joint between the desulfurizer 6 and the fuel gas supply pipe 12, and the fuel gas mixed with the air is modified. When supplied to the mass device 3, the power generation efficiency of the fuel cell 1 may be reduced.

  Therefore, in the present invention, as shown in FIG. 1, the relief valve 5 is provided in front of the reformer 3 (upstream of the reformer 3) (in the fuel gas supply pipe 12 on the front side of the reformer 3). Since the fuel gas is supplied to the desulfurizer 6 with the original pressure from the fuel gas supply source, the desulfurizer 6 and the fuel gas are replaced when the desulfurizer 6 is replaced and reconnected. When the supply pipe 12 is not firmly fastened, the fuel gas leaks from the joint, thereby detecting the leakage of the fuel gas (that is, the desulfurizer 6 and the fuel gas supply pipe 12 are connected to each other). It can be easily determined whether or not it is firmly connected.) In detecting the leakage of the fuel gas, a gas leakage detection sensor is provided in the vicinity of the desulfurizer 6, and the leakage of the fuel gas can be detected by the gas leakage detection sensor.

  In the fuel cell device of the present invention, the relief valve 5 is provided on the downstream side of the gas pump 4, and the relief valve 5 is set to open at a pressure larger than the gas pressure on the fuel gas supply side (upstream side). Therefore, by operating the gas pump 4 and discharging the fuel gas supplied from the fuel gas supply source, a pressure greater than the gas source pressure is applied to the relief valve 5, thereby opening the relief valve 5 and fuel. Since the gas flows, the fuel cell 1 can be supplied with a low flow rate fuel gas (city gas, etc.). For example, even when the amount of power generation is small, such as at night, the fuel cell 1 can efficiently generate power. it can.

  In addition, by using the relief valve 5 as the supply pressure regulator 5, the cost can be reduced, and the fuel cell device can be further reduced in price.

  FIG. 2 shows another embodiment of the fuel cell device of the present invention, and shows an example in which a pressure reducing valve is provided as the supply pressure regulator 13.

  The pressure reducing valve 13 is for reducing the pressure on the downstream side. Therefore, for example, when city gas is supplied as fuel gas, the upstream side of the pressure reducing valve 13 has a gas source pressure of 1.5 to 3.0 kPa, and the downstream side has a pressure lower than the source pressure on the fuel gas supply side. Since the state is maintained, a small amount of fuel gas can be supplied to the reformer 3 (fuel cell 1) by the gas pump 4 without being affected by the original pressure of the fuel gas (city gas or the like). In addition to the pressure reducing valve 13, a governor or the like that can be depressurized at a pressure lower than the gas pressure of the fuel gas supply source can be used.

  FIG. 3 shows still another embodiment of the fuel cell device of the present invention. In FIG. 3, a fuel gas supply pipe 12 is used instead of the relief valve 5 and the pressure reducing valve 13 as a supply pressure regulator. A supply pressure regulator comprising: a solenoid valve 14 provided in the valve; and a resistance pipe 15 that bypasses the solenoid valve 14 and can lower the gas pressure of the downstream fuel gas below the original pressure of the fuel gas. ing.

  In such a supply pressure regulator, by closing the solenoid valve 14, the fuel gas flows through the resistance tube 15, so that the gas pressure on the downstream side of the resistance tube 15 is changed to the upstream side of the resistance tube 15 (source of fuel gas). Therefore, a low flow rate fuel gas can be supplied to the reformer 3 (fuel cell 1) by the gas pump 4 without being affected by the original pressure on the fuel gas (city gas, etc.) supply side. it can.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.

  For example, propane gas can be used as the fuel gas, and the present invention can be used effectively in these cases.

  In the case where the desulfurizer 6 is composed of a cylindrical container having a desulfurization catalyst therein, the supply pressure regulator is provided downstream immediately after the desulfurizer 6 in order to simply suppress the negative pressure of the desulfurizer 6. It is also possible to arrange the supply pressure regulator 5 on the side. Even in this case, since it is possible to suppress the desulfurizer 6 from becoming a negative pressure, it is possible to easily determine the leakage of the fuel gas. However, in this case, since the downstream side of the supply pressure regulator 5 (for example, the gas flow meter 8 and the gas pump 4) may become negative pressure, care must be taken when replacing the desulfurizer 6 with the entire container.

  Further, a fuel electrode support type hollow plate type fuel cell having a fuel electrode on the inside and an oxygen electrode on the outside as the fuel cell 1 has been shown. For example, an air electrode support type with an oxygen electrode on the inside and a fuel electrode on the outside is shown. A fuel cell device in which another fuel cell such as a hollow plate type fuel cell or a polymer electrolyte fuel cell is accommodated can also be used.

It is a block diagram which shows an example of a structure of the fuel cell apparatus of this invention which used the relief valve as a supply pressure regulator. It is a block diagram which shows an example of a structure of other embodiment of the fuel cell apparatus of this invention which used the pressure-reduction valve as a supply pressure regulator. It is a block diagram which shows an example of a structure of further another embodiment of the fuel cell apparatus of this invention which used the resistance pipe | tube as a supply pressure regulator. It is a block diagram which shows the structure of the conventional fuel cell apparatus.

Explanation of symbols

1: Fuel cell 2: Storage container 3: Reformer 4: Gas pump 5: Relief valve 6: Desulfurizer 7, 14: Solenoid valve 8: Gas flow meter 9: Buffer 10: Controller 12: Fuel gas supply pipe 13: Pressure reducing valve 15: resistance tube

Claims (2)

A fuel cell device comprising: a fuel cell module containing a fuel cell; and a fuel gas supply device for supplying hydrogen to the fuel cell module,
The fuel gas supply device comprises:
A desulfurizer for removing sulfur in hydrocarbon gas supplied from a hydrocarbon gas supplier;
A gas flow meter for measuring the flow rate of the desulfurized hydrocarbon gas;
And gas pump for pumping the desulfurized said hydrocarbon gas,
A relief valve or a pressure reducing valve capable of lowering the supply pressure of the pumped hydrocarbon gas below the original pressure of the hydrocarbon gas supply source;
A reformer for reforming the hydrocarbon gas whose supply pressure is adjusted to hydrogen, and a fuel gas supply pipe connected in this order;
It further has a control unit for adjusting the flow rate of the pumped hydrocarbon gas by controlling the operation of the gas pump based on the flow rate of the desulfurized hydrocarbon gas measured by the gas flow meter. ,
The fuel cell device according to claim 1, wherein the relief valve or the pressure reducing valve opens in accordance with a pressure applied to the relief valve or the pressure reducing valve by the hydrocarbon gas sent under pressure . The fuel cell device according to claim 1, wherein the fuel cell is a solid oxide fuel cell.

Images