JP2011204430A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system that avoids a channel blockade due to condensed water remaining in an air circulation path during stopping of the fuel cell system, when the fuel cell system restarts, and suppresses lowering of performance and deterioration.SOLUTION: When staring supplying air to a fuel cell, the fuel cell system opens a on-off valve to control it to supply the air to the fuel cell, and adjusts such that air quantity supplied in the fuel cell becomes a prescribed quantity, after bringing pressure loss of the channel back to normal by discharging the condensed water remaining in the channel with air more than a predetermined flow rate outside the system.

Description

  The present invention relates to a fuel cell system that generates electricity by supplying a fuel gas generated by reforming a hydrocarbon-based raw material to a fuel cell.

  In a fuel cell, hydrogen or a hydrogen-rich gas is supplied to one of electrodes sandwiching an electrolyte, and an oxidant gas such as oxygen-containing air is supplied to the other to generate power by an electrochemical reaction. When a fuel cell generates electricity, heat is generated at the same time as the electric power. A cogeneration system that collects this heat and uses it as heat energy together with the electric power generated by the fuel cell has recently attracted attention as a fuel cell system. Yes.

  As one of the methods for generating hydrogen-rich gas (hereinafter referred to as fuel gas) necessary for power generation of a fuel cell, a fuel cell system uses a hydrocarbon-based raw material gas such as city gas or LPG, or a liquid such as methanol or kerosene. Generally, a hydrogen generator having a reforming section for reforming by introducing a hydrocarbon-based raw material together with steam is generally used.

  In addition, the fuel cell has a catalyst on the electrode in order to promote the electrochemical reaction, and this catalyst is often poisoned by carbon monoxide and has a property of lowering the performance. Therefore, in a hydrogen generator, after reforming a hydrocarbon-based raw material in a reforming section to generate a fuel gas, air is introduced to reduce the concentration of carbon monoxide in the fuel gas. In general, a selective oxidation unit that oxidizes carbon monoxide in the reformed gas is produced, and a fuel gas having a reduced carbon monoxide concentration is generated and supplied to the fuel cell.

  Furthermore, even if fuel gas with a reduced carbon monoxide concentration is supplied to the fuel cell, carbon dioxide in the fuel gas undergoes a reverse shift reaction by the electrode catalyst of the fuel cell to generate carbon monoxide. As a result, the fuel cell electrode catalyst may be poisoned and the performance of the fuel cell may be degraded. Therefore, a small amount of air (hereinafter referred to as bleed air) is mixed in the fuel gas, and the reverse shift reaction is performed. A fuel cell system has also been proposed in which carbon monoxide generated in the above is burned with an electrode catalyst of the fuel cell to avoid poisoning of the catalyst.

  In the fuel cell system as described above, air supplied as an oxidant gas to the fuel cell (hereinafter referred to as “cathode air” as appropriate), air supplied to the selective oxidation unit (hereinafter referred to as “selective oxidized air” as appropriate), and bleed. It is necessary to supply each of the three types of air at a predetermined flow rate, and providing each of the air supply unit, the flow rate measurement unit, and the flow rate control unit increases the cost and reduces the external dimensions of the fuel cell system. Along with the increase in size, a large installation space was required. In addition, there is a problem that the operation sound becomes louder when a plurality of air supply means operate simultaneously.

  In order to solve the above-mentioned problem, a fuel cell system that supplies selective oxidation air and bleed air with a single air supply device has been proposed (see Patent Document 1). This conventional fuel cell system is provided with a fixed orifice for adjusting the difference in pressure loss between the two flow paths in advance so that the selective oxidization air and the bleed air have a predetermined diversion ratio in the bleed air path. Therefore, it is possible to control the flow rate of the selective oxidation air and the flow rate of the bleed air to a predetermined flow rate with a single flow rate detection means.

  In another conventional fuel cell system, there is shown a fuel cell system in which cathode air supplied to a fuel cell and air supplied to a hydrogen generator are supplied by one air supply device (Patent Document 2). (See FIG. 1).

  FIG. 10 is a schematic diagram showing a configuration of a conventional fuel cell system described in Patent Document 2. As shown in FIG. As shown in FIG. 10, the air supplied from the compressor 100, which is an air supply device, is supplied to the fuel cell 102 via the cathode air path 101. The cathode air path 101 is connected to the hydrogen generator 103 on the way. The air is branched to the connected branch air path 104 and a part of the air supplied from the compressor 100 is supplied to the hydrogen generator 103. Further, the branch air path 104 is provided with an air flow meter 105 as a flow rate detecting means and an air control valve 106 as a flow rate adjusting means, and the control unit 107 performs air flow based on the air flow rate detected by the air flow meter 105. The degree of opening of the control valve 106 is adjusted so that a predetermined flow rate of air necessary for the hydrogen generator 103 is supplied.

  Patent Document 2 does not describe a specific method for adjusting the flow rate of cathode air supplied to the fuel cell 102. However, the ratio at which the air supplied from the compressor 100 is divided into the cathode air path 101 and the branch air path 104 (hereinafter, referred to as a diversion ratio as appropriate) is a path downstream of the fuel cell 102 and its gas flow. Is determined by the ratio of the pressure loss between the cathode air path 101 including the air control valve 106 and the hydrogen generator 103 and the branch air path 104 including the downstream path with respect to the gas flow. In view of this, the relationship between the opening degree of the air control valve 107 and the diversion ratio between the cathode air path 101 and the branch air path 104 is stored in the control unit 107 in advance, so that the opening degree of the air control valve 106 and the air From the flow rate detected by the flow meter 105, the flow rate of the cathode air supplied to the fuel cell 102 via the cathode air path 101 is determined, and based on this, the number of revolutions of the compressor 100 is controlled by the control unit 107, and the compressor 100 It is possible to adjust the flow rate of cathode air supplied to the fuel cell to a predetermined flow rate by adjusting the amount of air supplied from the fuel cell.

  With this configuration, in the conventional fuel cell system described in Patent Document 2, it is possible to further reduce the number of air supply devices and flow rate detection means compared to the fuel cell system described in Patent Document 1.

JP 2006-210131 A JP 2001-332284 A

  However, the conventional fuel cell system has the following problems.

  That is, when the fuel cell system is stopped, the water vapor generated on the air side inside the fuel cell by power generation causes the air flow path or fuel inside the fuel cell through which the cathode air circulates due to a decrease in the temperature of the fuel cell system. It condenses in the path for exhausting air from the battery. And this condensed water accumulates in the path | route through which cathode air distribute | circulates, reduces the cross-sectional area of a path | route, or obstruct | occludes a path | route depending on the case. As a result, the pressure loss of the path through which the cathode air flows increases compared to the normal case where there is no condensed water, and when the fuel cell system is started again, the diversion flow stored in advance by the control unit. Thus, there is a problem in that only air having a lower flow rate than the cathode air necessary for the fuel cell is supplied, so that the performance of the fuel cell is lowered and deterioration is promoted. In addition, since the flow rate of the cathode air supplied to the fuel cell is small, the flow rate of the air supplied to at least one of the hydrogen generator and the fuel gas path is increased from a predetermined flow rate. There existed a subject that performance fell and deterioration was accelerated | stimulated.

  In the present invention, in consideration of the problems of the conventional fuel cell system, air supplied to at least one of the hydrogen generator and the fuel gas path and cathode air are supplied by a single air supply means with a simple configuration. Even if the fuel cell system is repeatedly started and stopped, air supplied to at least one of the hydrogen generator and the fuel gas path and the cathode air are diverted at a predetermined ratio, and a predetermined flow rate is obtained. It is an object of the present invention to provide a fuel cell system that can be supplied by the above-described method and can suppress the deterioration of the performance and deterioration of the fuel cell system.

  In order to solve the above problems, a fuel cell system according to the present invention includes a fuel cell that generates power using fuel gas and air, and a hydrogen having a reforming section that generates a hydrogen-rich reformed gas from raw material and water. A generator, a fuel gas path through which the fuel gas generated by the hydrogen generator is circulated to the fuel cell, an air supply means for supplying air, and an air supplied from the air supply means is circulated to the fuel cell. A cathode air path, a branch air path that branches from the cathode air path and distributes air to at least one of the hydrogen generator and the fuel gas path, and the fuel cell disposed in the cathode air path. A cathode air supply blocking means for supplying or blocking air, and when the supply of air to the fuel cell is started, the cathode air supply blocking means is first opened. Control is performed so that air is supplied to the fuel cell, and the air supplied to the fuel cell is controlled to be supplied at a flow rate higher than a first predetermined flow rate, and then the air supplied to the fuel cell Includes a control unit for controlling the air supply means so that the first predetermined flow rate is maintained for a predetermined time.

  As a result, when the fuel cell system is started and the supply of cathode air to the fuel cell is started, first, the condensed water collected in the path through which the cathode air flows when the fuel cell system is stopped is first predetermined. Extrude the fuel cell system out of the fuel cell system with air above the flow rate, return the pressure loss of the path through which the cathode air circulates to normal, and then supply the first predetermined flow rate air required for fuel cell power generation Thus, by controlling the air supply means to adjust the air flow rate, it is possible to supply a predetermined flow rate of air to the cathode air path and the branch air path.

  According to the fuel cell system of the present invention, it is possible to repeatedly start and stop the fuel cell system with a simple configuration in which the selective oxidation air and the cathode air are separately supplied at a predetermined ratio by one air supply means. A selective oxidation air and cathode air can be supplied at a predetermined flow rate, and a fuel cell system capable of suppressing deterioration in performance and deterioration of the fuel cell can be provided.

Schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 1 of the present invention. Timing chart showing operation of main part of fuel cell system according to Embodiment 1 Schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 2 of the present invention. Schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 3 of the present invention. Schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 4 of the present invention. Schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 5 of the present invention. Timing chart showing operation of main part in start-up operation of fuel cell system according to Embodiment 5 Schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 6 of the present invention. Timing chart showing operation of main part in start-up operation of fuel cell system according to Embodiment 6 Schematic diagram schematically showing the configuration of a conventional fuel cell system

  The first invention is a fuel cell that generates power using fuel gas and air, a hydrogen generator having a reforming section that generates hydrogen-rich fuel gas from raw material and water, and the hydrogen generator. A fuel gas path for flowing fuel gas to the fuel cell; an air supply means for supplying air; a cathode air path for flowing air supplied from the air supply means to the fuel cell; and a branch from the cathode air path A cathode air supply shut-off for supplying or shutting off air to the fuel cell disposed in the cathode air path, and a branch air path for allowing air to flow through at least one of the hydrogen generator and the fuel gas path When the supply of air to the fuel cell is started, first, the cathode air supply shut-off unit is opened to supply air to the fuel cell. In addition, control is performed so that the air supplied to the fuel cell is supplied at a flow rate higher than the first predetermined flow rate for a predetermined time, and then the air supplied to the fuel cell becomes the first predetermined flow rate. And a fuel cell system provided with a control unit for controlling the air supply means.

  Thus, even if water vapor is condensed in the path through which the cathode air flows when the fuel cell system is stopped, when starting the fuel cell system again and starting the supply of the cathode air to the fuel cell, By pushing the condensed water out of the fuel cell system with air of a first predetermined flow rate or higher and then adjusting to a first predetermined air flow rate required for power generation, the cathode air path and the branch air path Since the ratio of the pressure loss can be set to a predetermined ratio, and air of a predetermined flow rate can be supplied to the cathode air path and the branch air path, the air supplied to the branch air path by one air supply means And the cathode air are divided and supplied at a predetermined ratio. Even if the fuel cell system is repeatedly started and stopped, the air and cathode supplied to the branch air path are Over de can be supplied with air at a predetermined flow rate, it is possible to provide a fuel cell power generation system capable of suppressing the performance degradation and accelerated deterioration of the fuel cell.

  According to a second aspect of the present invention, the fuel cell system according to the first aspect further includes a flow rate detection unit that detects a flow rate of air supplied by the air supply unit, and the control unit adjusts the air flow rate detected by the flow rate detection unit. A fuel cell system for controlling the air supply means based on the fuel cell system.

  Thereby, in addition to the effect of the first invention, it becomes possible to accurately control the flow rate of the air supplied from the air supply means to the flow rate necessary for the operation of the fuel cell system. It is possible to suppress the fuel cell performance from being reduced and the deterioration of the fuel cell performance and the promotion of the deterioration due to the decrease in the efficiency of the fuel cell system and the lack of air.

  According to a third aspect of the present invention, the flow rate detecting means of the fuel cell system according to the second aspect of the invention detects an air flow rate for detecting an air flow rate supplied to at least one of the hydrogen generator and the fuel gas path provided in the branch air path It is a detection means, and the control unit controls the air supply means based on the air flow rate detected by the air flow rate detection means.

  In a normal fuel cell system, compared to the flow rate of cathode air supplied to the fuel cell, the flow rate of air supplied to the hydrogen generator via the branch air path, or the bleed air supplied to the fuel cell mixed with fuel gas The amount of air of at least one of the above flow rates or the sum of the air flow rate supplied to the hydrogen generator and the bleed air flow rate is smaller. Therefore, according to the fuel cell system of the third invention, the fuel of the second invention is used to control the flow rate of air supplied by the air supply means based on the air flow rate supplied to the branch air path having a small flow rate. Compared with the battery system, the air flow rate can be controlled more accurately.

  According to a fourth aspect of the present invention, there is provided a diversion ratio for adjusting a ratio of distributing the air supplied by the air supply means to the cathode air path and the branch path in the fuel cell system according to any one of the first to third aspects. The adjusting means is provided at a branch point between the cathode air path and the branch air path, or at either the cathode air path or the branch air path.

  This makes it possible to control the flow rate of the cathode air and the air supplied to the branch air path by adjusting the operation amount such as the rotation speed of the air supply means and the diversion ratio by the diversion ratio adjustment means. Therefore, it is possible to adjust the air flow rate relatively easily.

  A fifth invention is a fuel cell system in which the diversion ratio adjusting means of the fuel cell system of the fourth invention is a diversion valve provided at a branch point between the cathode air path and the branch path. Thereby, it is possible to adjust the diversion ratio between the cathode air and the air supplied to the branch air path with a relatively simple configuration.

  In a sixth aspect of the invention, the diversion ratio adjusting means of the fuel cell system of the fourth aspect of the invention is a flow resistance variable means for changing the flow resistance of the cathode air path provided in the cathode air path. . Thereby, it is possible to adjust the diversion ratio between the cathode air and the air supplied to the branch air path with a relatively simple configuration.

  In a seventh aspect of the invention, the diversion ratio adjusting means of the fuel cell system of the fourth aspect of the invention is a flow resistance variable means for changing the flow resistance of the branch air path provided in the branch air path. . Thereby, it is possible to adjust the diversion ratio between the cathode air and the air supplied to the branch air path with a relatively simple configuration.

  According to an eighth aspect of the present invention, there is provided a flow rate of air supplied to the branch air path before and after the controller of the fuel cell system according to any one of the fourth to seventh aspects starts supplying cathode air to the fuel cell. The diversion ratio adjusting means is controlled so as not to change.

  As a result, the flow rate of the air supplied to the branch air path immediately after opening the cathode air supply shut-off means is excessively higher than the required flow rate, and the performance of the fuel cell system is reduced and the deterioration is suppressed. can do.

  In a ninth invention, the diversion ratio adjusting means of the fuel cell system of the fifth or sixth invention also serves as the cathode air supply shut-off means. That is, when the diversion ratio adjusting means is a diversion valve, the supply of air to the fuel cell can be cut off by controlling so that all the air supplied from the air supply means is supplied to the branch path side. In the case where the diversion ratio adjusting means is a flow path resistance variable means provided in the cathode air path, air supply to the fuel cell is achieved by closing the cathode air path with the flow path resistance variable means. Can be shut off.

  Thereby, the configuration of the fuel cell system can be simplified.

  According to a tenth aspect of the invention, there is provided a hydrogen generator of the fuel cell system according to any one of the first to ninth aspects, wherein a reforming unit that generates hydrogen-rich fuel gas from a raw material and water, and the reforming unit And a selective oxidation section that removes carbon monoxide in the generated fuel gas, and the branch air path is a selective oxidation air path through which air flows to the selective oxidation section.

  Thereby, since the concentration of carbon monoxide in the fuel gas generated in the reforming section can be reduced, poisoning of the electrode catalyst of the fuel cell can be suppressed.

  In an eleventh aspect of the invention, the branch air path of the fuel cell system according to any one of the first to ninth aspects causes air to flow through the fuel gas path to be mixed into the fuel gas and to be supplied to the fuel cell. It is a bleed air path for.

  Thereby, it is possible to suppress the poisoning of the electrode catalyst caused by the reverse shift reaction of carbon monoxide from the carbon dioxide in the fuel gas due to the action of the electrode catalyst of the fuel cell.

  In a twelfth aspect of the invention, the fuel cell system of the tenth aspect of the invention branches from the selective oxidative air path and causes the fuel gas path to circulate a part of the air supplied to the selective oxidative air path to thereby produce the fuel A bleed air path that is mixed with gas and supplied to the fuel cell, and the air flow rate supplied to the selective oxidizer and the air flow rate supplied to the fuel gas path in the bleed air path have a predetermined ratio It is provided with a flow rate adjusting means for adjusting so as to be.

  As a result, the concentration of carbon monoxide in the fuel gas supplied from the hydrogen generator to the fuel cell is reduced, and in addition, carbon monoxide is reversely shifted from carbon dioxide in the fuel gas by the action of the electrode catalyst of the fuel cell. It is possible to suppress poisoning of the electrode catalyst caused by the reaction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
First, the configuration of the fuel cell system according to Embodiment 1 of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 1 of the present invention. In FIG. 1, a solid line connecting the components constituting the fuel cell system indicates a path through which water, fuel gas, oxidant gas, and the like flow. The arrows on the solid lines indicate the direction in which water, fuel gas, oxidant gas, and the like flow during normal operation. Moreover, the broken line which connects between each component has shown the input and output of the control signal. Further, FIG. 1 shows only components necessary for explaining the present invention, and illustration of other components is omitted.

  As shown in FIG. 1, the fuel cell system 1 according to the present embodiment includes a fuel cell 2 as a main body of the power generation unit. As the fuel cell 2, a solid polymer fuel cell is used in the present embodiment.

  The fuel cell 2 includes a fuel gas containing abundant hydrogen discharged from a hydrogen generator 3 to be described later and supplied to an anode flow path 2a in the fuel cell 2, and an air blower 17 serving as an air supply unit to be described later. Using oxidant gas (usually air) supplied to the cathode flow path 2b in the power generator 2, electric power is generated so as to output predetermined power. Although not shown, heat generated when the fuel cell 2 generates electricity is recovered by cooling water supplied to a cooling water flow path (not shown) in the fuel cell 2 and discharged outside the fuel cell 2. Is done. The detailed description of the internal configuration of the fuel cell 2 is omitted here because the internal configuration of the fuel cell 2 and the internal configuration of a general polymer electrolyte fuel cell are the same.

  As shown in FIG. 1, the fuel cell system 1 includes at least a reformer 3a as the hydrogen generator 3 according to the present invention. The reformer 3a supplies steam reforming by supplying a raw material containing an organic compound composed of at least carbon and hydrogen and steam into a packed bed (not shown) of a reforming catalyst heated to a predetermined temperature. The fuel gas containing abundant hydrogen is generated from the raw material by advancing the quality reaction. As the raw material supplied to the reformer 3a, typically, a gaseous hydrocarbon-based raw material such as city gas, natural gas, or LPG is used. However, liquid hydrocarbon raw materials such as methanol and kerosene may be used. However, when using a liquid raw material, it is preferable to vaporize before supplying to the reformer 3a.

  The supply of the raw material to the reformer 3a is performed by a raw material supply device 4 described later via a raw material gas supply path 5 connecting the raw material supply device 4 and the reformer 3a. In the following description, “connected” includes the case of connection via a route or the like. The supply of water vapor to the reformer 3a is performed by mixing the water vapor generated by evaporating the process water with a water vapor generator 3d described later into the raw material gas supply path 5.

  The hydrogen generator 3 of the fuel cell system 1 of Embodiment 1 includes the reformer 3a and a transformer for reducing carbon monoxide in the fuel gas discharged from the reformer 3a. 3b and a selective oxidizer 3c as a CO remover are sequentially connected.

  The shifter 3b is connected to the reformer 3a, and the fuel gas generated by the reformer 3a is introduced into a packed bed (not shown) of shift catalyst of the shifter 3b. The fuel gas produced by the reformer 3a contains carbon monoxide and carbon dioxide in addition to hydrogen, and water vapor not used in the reforming reaction, but was introduced in the transformer 3b. Carbon monoxide and water vapor in the fuel gas are subjected to a shift reaction to generate carbon dioxide and hydrogen.

  The selective oxidizer 3c is connected to the transformer 3b, and the fuel gas whose carbon monoxide concentration is reduced by the transformer 3b is introduced into a packed bed (not shown) of the selective oxidation catalyst, and further contains oxygen. Gas, that is, generally air, is supplied through a selective oxidizing air passage 19 described later. In the selective oxidizer 3c, carbon monoxide in the fuel gas remaining in the shift reaction is oxidized with oxygen in the air to carbon dioxide, and the carbon monoxide concentration in the fuel gas is reduced to about 10 ppm or less. The air supplied to the selective oxidizer 3c is referred to as selective oxidant air and will be described below.

  The hydrogen generator 3 includes a water vapor generator 3d, and the water vapor generator 3d is configured to generate water vapor by evaporating process water. As heat for evaporating the process water, reaction heat generated in the shift reaction and the selective oxidation reaction in the shift converter 3b and the selective oxidizer 3c and combustion exhaust heat in the burner section 3e described later are used. It is also possible to provide a heating means such as an electric heater separately. Further, the process water is supplied from the process water tank 7 by the process water supply pump 6 to the steam generator 3d and is evaporated by the steam generator 3d to generate steam, and then the steam connected to the source gas supply path 5 is supplied. Via the supply path 8, it is mixed with the raw material gas and supplied to the reformer 3a. Moreover, the steam supply path 8 may be directly connected to the reformer 3a.

  In addition, the hydrogen generator 3 includes a burner unit 3e for burning, for example, a raw material gas in order to heat a reforming catalyst (not shown) filled in the reformer 3a. The burner unit 3e includes a gas discharged from the fuel cell 2 containing hydrogen that has not been used for power generation in the fuel cell 2 (hereinafter referred to as off-gas), a fuel gas generated by the hydrogen generator 3, and a raw material supply device. At least one of the raw material gases supplied by 4 is burned to heat the reforming catalyst and generate reforming heat necessary for the reforming reaction. Further, a combustion air fan 9 for supplying air necessary for combustion of the raw material gas or the like in the burner unit 3e from the atmosphere is connected to the burner unit 3e via a combustion air path 10, and the combustion air fan 9 Is controlled by a control unit 22 to be described later so that an air amount necessary for completely burning the raw material gas to be burned is supplied. Further, although not shown, the combustion exhaust gas after burning in the burner portion 3e is heated out of the fuel cell system 1 after heating the steam generator 3d via the combustion exhaust gas path.

  The reformer 3a includes a temperature sensor 3f for measuring the temperature of a reforming catalyst (not shown) filled in the reformer 3a. This temperature sensor 3f is embedded in the reforming catalyst in consideration of the seal configuration so that the inside and outside of the reformer 3a do not communicate with each other from the outside of the reformer 3a. Further, the temperature sensor 3f is wired so as to output the temperature of the reforming catalyst as an electric signal to the control unit 22 described later. Although not shown, a temperature sensor for detecting the temperature of the shift catalyst and a temperature sensor for detecting the temperature of the selective oxidation catalyst are provided in the shift converter 3b and the selective oxidizer 3c, respectively. It is wired to output to.

  As shown in FIG. 1, the fuel cell system 1 includes a raw material supply device 4. The raw material supply device 4 is a booster pump that pressurizes a raw material gas such as natural gas supplied from an infrastructure such as natural gas during the power generation operation of the fuel cell system 1. Then, the raw material is supplied to the reformer 3a. Here, the raw material supply apparatus 4 is configured so that the supply amount of the raw material gas supplied to the reformer 3a can be appropriately adjusted as necessary by the control unit 22 described later.

  The fuel cell 2 and the hydrogen generator 3 are connected to the selective oxidizer 3c of the hydrogen generator 3 at one end in order to supply the fuel gas generated by the hydrogen generator 3 to the anode flow path 2a of the fuel cell 2. The other end of the fuel cell 2 is connected to the fuel gas path 11 connected to the anode flow path 2 a of the fuel cell 2. Furthermore, the anode flow path 2a of the fuel cell 2 and the burner part 3e are connected by an off-gas path 12 having one end connected to the anode flow path 2a of the fuel cell 2 and the other end connected to the burner part 3e. Further, the fuel gas path 11 is branched into a bypass path 13 in the middle, and is connected so as to merge with the middle of the offgas path 12.

  A fuel inlet valve 14 is located closer to the fuel cell 2 than the branch point of the fuel gas path 11 with the bypass path 13, and a fuel outlet valve is located closer to the fuel cell 2 than the junction with the bypass path 13 of the offgas path 12. 15 and a bypass valve 16 are provided in the bypass path 13, respectively, and are arranged so as to be arbitrarily opened or closed by a control unit described later. The fuel inlet valve 14, the fuel outlet valve 15, and the bypass valve 16 are electromagnetic valves that can be arbitrarily switched between open and closed by the control unit 22, whereby the fuel inlet valve 14 and the fuel outlet valve 15 are closed. If the bypass valve 16 is opened in this way, the gas supplied from the selective oxidizer 3c can be supplied directly to the burner unit 3e without going through the fuel cell 2, and conversely, the fuel inlet valve 14 and the fuel outlet If the valve 15 is opened and the bypass valve 16 is closed, the fuel gas generated by the hydrogen generator 3 can be supplied to the fuel cell 2.

  As shown in FIG. 1, the fuel cell system 1 includes an air blower 17 as air supply means. The air blower 17 supplies air (hereinafter referred to as cathode air) as an oxidant gas to the cathode flow path 2b of the fuel cell 2 via the cathode air path 18 by sucking air from the atmosphere. It is. Furthermore, the air blower 17 is disposed so that the amount of air supplied from the air blower 17 can be adjusted by controlling the number of rotations by a control unit 22 described later. Note that the air blower 17 used in the fuel cell system 1 of the first embodiment has a flow rate with respect to a change in pressure loss in a path through which the supplied air flows in the range of the air flow rate used in the fuel cell system 1. An air blower with characteristics that hardly changed was used. Thus, if the control unit 22 adjusts the rotation speed of the air blower 17 to be a predetermined rotation speed, air of a predetermined flow rate is supplied from the air blower 17.

  Further, the cathode air path 18 is branched from the selective oxidation air path 19 at a branch point X in the middle, and the selective oxidation air path 19 which is this branch air path has one end at the branch point X and the other. The end is connected to the selective oxidizer 3c. Further, on the fuel cell 2 side of the cathode air passage 18 from the branch point X, an air inlet valve 20 as an on-off valve is disposed as a cathode air supply shut-off means, and the controller 22 can be arbitrarily opened or closed. It has been made possible to change.

  Here, when the air inlet valve 20 is opened, such as during power generation operation of the fuel cell system 1, a part of the air supplied from the air blower 17 is converted into cathode air via the cathode air path 18. 2 is supplied to the selective oxidizer 3c through the selective oxidizing air path 19 as selective oxidizing air. At this time, the ratio between the flow rate of the cathode air and the flow rate of the selectively oxidized air (hereinafter, referred to as a diversion ratio as appropriate) is the same as that of the cathode air path 18 including the air inlet valve 20 downstream from the branch point X and the fuel cell 2. The cathode flow path 2b, the pressure loss Pc of the cathode exhaust air path 21, the selective oxidation air path 19, the selective oxidizer 3c, the fuel gas path 11 including the fuel inlet valve 14, and the anode flow path 2a of the fuel cell 2. And the ratio between the off-gas path 12 including the fuel outlet valve 15 and the pressure loss Pa of the entire path until the combustion exhaust gas is exhausted from the fuel cell system 1 via the burner portion 3e. Therefore, in the fuel cell system according to the embodiment of the present invention, the air supplied from the air blower 17 during power generation is divided into the cathode air passage 18 and the selective oxidation air passage 19 downstream from the branch point X at a predetermined ratio. As you can see, the pressure loss in each path is designed.

  Further, air containing oxygen that has not been used for power generation (hereinafter referred to as cathode exhaust air) is exhausted out of the fuel cell system 1 from the cathode exhaust air path 21 connected to the cathode flow path 2 b of the fuel cell 2. Is done.

  Furthermore, the fuel cell system 1 includes a control unit 22. The control unit 22 appropriately controls the operation of each component constituting the fuel cell system 1. Here, the control unit 22 includes, for example, a storage unit, a timing unit, a central processing unit (CPU), and the like, although not particularly illustrated in FIG. A program related to the operation of each component of the fuel cell system 1 is stored in advance in the storage unit of the control unit 22, and the control unit 22 operates the fuel cell system 1 based on the program stored in the storage unit. Is appropriately controlled.

  Next, the operation of the fuel cell system 1 according to Embodiment 1 of the present invention will be described in detail with reference to the drawings.

  Here, “at the time of start-up operation” in the present embodiment means “after the start command is output from the control unit 22, the current is taken out from the fuel cell 2 by the power generation control unit not shown in FIG. 1 of the fuel cell 2. “At the time of stop operation” means “until the operation of the entire fuel cell system 1 is completely stopped after the stop command is output from the control unit 22”.

  During power generation of the fuel cell system 1, by driving the raw material supply device 4, a predetermined flow rate of raw material is supplied to the reformer 3a together with the steam generated by the steam generator 3d, and the reformer 3a, the transformer 3b, A high-quality fuel gas generated by sequentially flowing through the selective oxidizer 3 c passes through the opened fuel inlet valve 14 and is supplied to the anode flow path 2 a of the fuel cell 2. At this time, the bypass valve 16 is in a closed state, and the fuel outlet valve 15 is in an open state.

  Further, by driving the air blower 17 at a predetermined rotational speed, a predetermined flow rate of air passes through the open air inlet valve 20 and is supplied to the cathode flow path 2 b of the fuel cell 2. At this time, a part of the air supplied from the air blower 17 is supplied to the selective oxidizer 3c through the selective oxidization air passage 19 at a predetermined flow rate according to a preset diversion ratio, and the concentration of carbon monoxide in the fuel gas It is used to reduce The following description will be made assuming that the rotation speed of the air blower 17 at this time is the third rotation speed.

In the fuel cell 2, an electrochemical reaction is caused by hydrogen in the fuel gas supplied to the anode channel 2a and introduced into the anode electrode, and oxygen in the cathode air supplied to the cathode channel 2b and introduced into the cathode electrode. Is done. In the electrochemical reaction, the reaction represented by the following formula (1) is performed on the anode electrode side, and the reaction represented by the following formula (2) is performed on the cathode electrode side.
_{^{2H 2 → 4H + + 4e -}} ··· (1)
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)

  Electricity is generated by this electrochemical reaction, and moisture is generated on the cathode electrode side. More specifically, electric power can be obtained when electrons on the anode electrode side move to the cathode electrode side through an external electric circuit (not shown). Hydrogen ions on the anode electrode side move to the cathode electrode side through the solid polymer membrane, and combine with oxygen to generate moisture. In order for hydrogen ions to pass through the solid polymer membrane, the solid polymer membrane is preferably wet. Therefore, in a general fuel cell system, cathode air supplied to the fuel cell is humidified before being supplied. Also in the fuel cell system of the present embodiment, the cathode air supplied to the fuel cell 2 is supplied after being humidified by a humidifier (not shown) provided on the cathode air path 18 downstream from the branch point X. In addition, the fuel gas supplied to the fuel cell 2 is generated from the raw material and water vapor by the hydrogen generator 3. At this time, a predetermined amount more than the amount of water vapor necessary for ideally performing the reforming reaction is produced. Since water vapor is supplied, the fuel cell 2 is supplied in a humidified state.

  Further, in order for the reactions shown in the above formulas (1) and (2) to be performed smoothly, a predetermined amount of fuel gas and cathode air are supplied to the fuel cell 2 in accordance with the amount of power generated by the fuel cell system 1. It is necessary to supply. For this reason, the raw material supply device 4 and the air blower 17 are controlled by the control unit 22 so that fuel gas and cathode air at a predetermined flow rate are supplied to the fuel cell 2. At this time, the flow rate of the cathode air supplied to the fuel cell 2 corresponds to the first predetermined flow rate.

  Off-gas containing hydrogen that has not been used for power generation is supplied to the burner unit 3e via the off-gas path 12, and burned together with combustion air separately supplied by the combustion air fan 9 in the burner unit 3e. Is used to maintain the temperature of the fuel cell system at a predetermined temperature, and then discharged outside the fuel cell system 1.

  Next, during the stop operation of the fuel cell system 1, the electrical connection with the external electric circuit is disconnected, and the driving of the raw material supply device 4 and the air blower 17 is stopped to stop the power generation of the fuel cell 2. At this time, the fuel inlet valve 14, the fuel outlet valve 15, and the air inlet valve 20 are closed.

  When the fuel cell system 1 stops and the temperature of the fuel cell 2 and the cathode air path 18 decreases, the inside of the cathode air path 18 after the humidifier (not shown), the cathode flow path 2b of the fuel cell 2, etc. The water vapor remaining in the cathode air and the cathode exhaust air is condensed and accumulated in the path.

  Next, the start-up operation of the fuel cell system, which is a feature of the present invention, will be described below.

  During the start-up operation of the fuel cell system 1, the following operation is performed under the control of the control unit 22.

  First, the temperature of each catalyst charged in the reformer 3a, the shifter 3b, and the selective oxidizer 3c of the hydrogen generator 3 is a predetermined temperature suitable for performing the reforming reaction, shift reaction, and selective oxidation reaction, respectively. The raw material gas is burned in the burner unit 3e so that each catalyst is heated. Specifically, the bypass valve 16 is opened for reasons described later, the raw material is supplied from the raw material supply device 4 to the hydrogen generator 3 with the fuel inlet valve 14 and the fuel outlet valve 15 closed, and the bypass passage 13 is To the burner unit 3e. At the same time, combustion air corresponding to the raw material supplied is supplied to the burner unit 3e by the combustion air fan 9 via the combustion air path 10, and combustion of the raw material is started in the burner unit 3e by an ignition device (not shown) provided in the burner unit 3e. .

  At this time, the temperature of the reforming catalyst is detected by the temperature sensor 3f, and similarly, the temperatures of the shift catalyst and the selective oxidation catalyst are detected by a temperature sensor (not shown). Further, the temperature of the shift catalyst and the selective oxidation catalyst is detected by the temperature sensor 3f by storing the correlation between the temperature of the reforming catalyst and each temperature of the shift catalyst and the selective oxidation catalyst in the control unit 22 in advance. You may make it judge from the temperature of a reforming catalyst.

  At this time, the steam generator 3d is also heated by the combustion of the burner portion 3e, the temperature of the steam generator 3d is increased to a temperature at which water can be evaporated, and the temperature of each catalyst is 100 ° C. or higher. When the temperature is raised to a temperature at which the steam does not condense, the process water supply pump 6 is driven to supply the process water from the process water tank 7 to the steam generator 3d in order to generate steam for advancing the steam reforming reaction. To do. The reforming reaction is started in the reformer 3a by mixing the steam generated in the steam generator 3d with the raw material gas in the current gas supply path 5 via the steam supply path 8 and supplying it to the reformer 3a. Is done.

  At the beginning of the start-up operation of the fuel cell system 1, the temperature of the reforming catalyst of the reformer 3a is heated by the burner unit 3e and gradually rises. Therefore, a predetermined temperature suitable for performing the reforming reaction. Not reached. For this reason, since the steam reforming reaction in the reformer 3a does not proceed suitably, the fuel gas discharged from the reformer 3a contains a large amount of carbon monoxide. Similarly, the temperature of the shift catalyst of the shift converter 3b and the temperature of the selective oxidation catalyst of the selective oxidizer 3c do not reach temperatures suitable for performing the shift reaction and the selective oxidation reaction. Therefore, the fuel gas discharged from the hydrogen generator 3 still contains a large amount of carbon monoxide. Therefore, in the present embodiment, when the start-up operation of the fuel cell system 1 is started, the temperature of each catalyst in the hydrogen generator 3 reaches a predetermined temperature, and high-quality fuel gas having a sufficiently low carbon monoxide concentration is generated. Until it becomes possible (until a predetermined operating condition is satisfied), the control unit 22 keeps the fuel gas flowing on the bypass path 13 side as described above.

  When the temperature of the selective oxidation catalyst of the selective oxidizer 3c reaches a predetermined temperature suitable for performing the selective oxidation reaction, a predetermined amount of air stored in the air blower 17 in advance by the control unit 22 is supplied. A predetermined amount of selective oxidant air is supplied to the selective oxidizer 3c through the selective oxidant air passage 19 by driving at a rotational speed of 1. At this time, by keeping the air inlet valve 20 closed, no air is supplied to the cathode flow path 2b of the fuel cell 2, and all the air supplied from the air blower 17 is supplied to the selective oxidizer 3c. In addition, the following description will be made with the rotation speed of the air blower 17 at this time as the first rotation speed.

  Further, when the temperature of each catalyst reaches a temperature suitable for performing each reaction and high quality fuel gas is generated in the hydrogen generator 3, the fuel inlet valve 14 and the fuel outlet valve 15 are opened. At the same time, by closing the bypass valve 16, supply of fuel gas to the anode flow path 2a of the fuel cell 2 is started. At this time, the supply of air to the cathode flow path 2b of the fuel cell 2 is not yet started for the reasons described later.

  When a predetermined time elapses after the supply of fuel gas to the anode flow path 2a of the fuel cell 2 is started, the control unit 22 opens the air inlet valve 20 to start supplying cathode air to the fuel cell 2. The power generation operation of the fuel cell system 1 is started.

  The supply of fuel gas to the fuel cell 2 is started before the air. When power generation is started in a state where hydrogen does not sufficiently flow through the electrodes of the fuel cell 2, hydrogen is generated by the reaction shown in the equation (1). This is because the electrons to be taken out from the carbon are taken out from the carbon of the anode electrode or carbon or metal constituting the separator because there is not enough hydrogen, and the members such as the electrode and separator constituting the fuel cell 2 are deteriorated. For this reason, after a predetermined time has elapsed until the hydrogen in the fuel gas has sufficiently spread to the anode electrode of the fuel cell 2, supply of cathode air to the fuel cell 2 is started and power generation is started.

  Here, the operation when starting the supply of cathode air to the fuel cell, which is a feature of the present invention, will be described in detail with reference to the drawings.

  FIG. 2 is a timing chart showing the operation of the main components and the change in the main flow rate before and after the supply of the cathode air to the fuel cell 2 is started. 2A shows changes in closing and opening of the air inlet valve 20, FIG. 2B shows changes in the rotational speed of the air blower 17 with respect to the operation of the air inlet valve 20 in FIG. 2A, and FIG. The change in the flow rate of air, (d) shows the change in the flow rate of the selectively oxidized air.

  As shown in FIG. 2, when the supply of cathode air to the fuel cell 2 is started, the air inlet valve 20 is opened, and at the same time, the rotational speed of the air blower 17 is controlled to the first rotational speed that has been controlled so far. The amount of air supplied from the air blower 17 is increased.

  However, at this time, condensed water is accumulated in the cathode air passage 18 and the cathode flow path 2b of the fuel cell 2 when the fuel cell system 1 is stopped as described above. Therefore, when the air blower 17 is driven at the third rotational speed so that the first predetermined flow rate of cathode air necessary for power generation is supplied to the fuel cell 2, the air flow rate supplied from the air blower 17 ( That is, the combined flow rate of the cathode air flow rate and the selective oxidation air flow rate is always the same predetermined flow rate due to the characteristics of the air blower used in the fuel cell system 1 of the first embodiment, but the condensed water is the cathode flow rate. Since the flow resistance of the path is increased by condensing in the path through which air flows, the diversion ratio deviates from the design value, and the flow rate of the selective oxidation air increases than expected, and conversely the flow rate of the cathode air Will be lower than expected. When the shunt ratio is adjusted by the ratio of the pressure loss of each path after branching as in the fuel cell system 1 of the first embodiment, the ratio of the pressure loss of the path deviates from the design value. May continue to operate the fuel cell system with the diversion ratio shifted.

  When power generation is performed in a state where the flow rate of the cathode air supplied to the fuel cell 2 is small, oxygen necessary for power generation by the fuel cell 2 is not supplied to the cathode electrode, and the power generation amount of the fuel cell 2 decreases, and the fuel cell The efficiency of the system decreases or the deterioration of the fuel cell 2 is promoted. On the other hand, when the flow rate of the selective oxidation air supplied to the selective oxidizer 3c is too large, the selective oxidation catalyst in the selective oxidizer 3b causes the oxidation reaction of hydrogen, which is an exothermic reaction, to proceed. When the temperature of 3c rises and the temperature deviates from a temperature suitable for performing the selective oxidation reaction, carbon monoxide cannot be sufficiently removed, and fuel gas having a high carbon monoxide concentration is supplied to the fuel cell 2 and the performance of the fuel cell 2 In other words, hydrogen that is originally supplied to the fuel cell 2 and used for power generation is consumed by an oxidation reaction with oxygen in an excessive amount of selectively oxidized air, and the efficiency of the fuel cell system is reduced.

  Therefore, in the fuel cell system 1 of the first embodiment, as shown in FIG. 2, when the supply of cathode air to the fuel cell 2 is started, the air inlet valve 20 is opened and at the same time the air blower 17 is rotated. The flow rate of the air supplied from the air blower 17 is increased by increasing the number from the first rotation number described above. At this time, first, the second rotation number described later, which is higher than the third rotation number described above. The control unit 22 performs control so as to increase the

  The second rotational speed of the air blower 17 is obtained in advance by the following experiment and stored in the control unit 22. That is, the flow rate of the cathode air that is diverted at the branch point X and supplied to the fuel cell 2 varies depending on the amount of condensed water accumulated when the fuel cell system 1 is stopped and the state of the blockage of the condensed water. However, the fuel cell system 1 is started from a state in which condensed water is accumulated in the path where the cathode air and the cathode exhaust air downstream from the branch point X circulate most in the state where the diversion ratio is the most, and the fuel cell 2 receives the cathode air. When the supply is started, the condition for the condensed air in the path to be discharged out of the fuel cell system 1 through the cathode exhaust air path 21 is obtained by the cathode air, and the rotation speed of the air blower 17 at that time is The number of rotations is stored in the control unit 22.

  Then, as shown in FIG. 2, after the air blower 17 is driven at the second rotational speed and the condensed water is discharged out of the fuel cell system 1, the control unit 22 supplies the fuel cell 2 with a first predetermined flow rate. Of the air blower 17 is controlled to be lowered to a third rotation speed at which a predetermined flow rate of selective oxidation air is simultaneously supplied to the selective oxidizer 3c. To start.

  Here, for a predetermined time during which the air blower 17 is driven at the second rotational speed, the condensed water accumulated in the path through which the cathode air flows is discharged out of the fuel cell system 1 via the cathode exhaust air path 21. The time required until the second rotation number is obtained in advance by an experiment for obtaining the second rotation number and stored in the control unit 22 in advance.

  Further, when the rotational speed of the air blower 17 is controlled to the second rotational speed, the flow rate of the selective oxidation air supplied to the selective oxidizer 3c also increases from a predetermined flow rate as shown in FIG. This is temporary. After the condensed water is discharged out of the fuel cell system 1 and the rotation speed of the air blower 17 is lowered to the third rotation speed, the diversion ratio returns to the design value and is selected. Since the flow rate of the oxidized air is also supplied at a predetermined flow rate, the efficiency of the fuel cell system is not reduced and the temperature of the selective oxidizer 3b is not increased. Here, the flow rate of the cathode air and the flow rate of the selective oxidation air shown in FIG. 2 are shown to change at a constant amount while the air blower 17 is driven at the second rotational speed. Actually, in the process of discharging condensed water, the cathode air flow rate gradually increases and the selective oxidation air flow rate gradually changes.

  As described above, in the fuel cell system according to the present embodiment, when the fuel cell system is stopped, the condensed water accumulated in the path through which the cathode air and the cathode exhaust air circulate is started when the supply of the cathode air to the fuel cell is started. , The cathode air is discharged out of the fuel cell system, and after the shunt ratio between the cathode air and the selective oxidation air is returned to the designed shunt ratio, the power generation operation can be started. With a simple configuration that supplies cathode air and selective oxidized air with air supply means, even if the fuel cell system is repeatedly started and stopped, it is possible to suppress the reduction in efficiency and deterioration of the fuel cell system. Is possible.

(Embodiment 2)
Next, the configuration of the fuel cell system according to Embodiment 2 of the present invention will be described with reference to the drawings.

  FIG. 3 is a schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 2 of the present invention. Also in FIG. 3, as in FIG. 1, the solid line connecting the components constituting the fuel cell system indicates a path through which water, fuel gas, oxidant gas, and the like flow. The arrows on the solid lines indicate the direction in which water, fuel gas, oxidant gas, and the like flow during normal operation. Moreover, the broken line which connects between each component has shown the input and output of the control signal. FIG. 3 also shows only the components necessary for explaining the present invention, and the illustration of other components is omitted. In FIG. 3, the same components as those of the fuel cell system 1 shown in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the fuel cell system 31 according to the second embodiment has substantially the same configuration as the fuel cell system 1 shown in the first embodiment, but the first embodiment is the following point. Different from the fuel cell system 1 shown in FIG.

  First, in the fuel cell system 1 shown in the first embodiment, the selective oxidizer 3c using the selective oxidation reaction is used as the CO remover, whereas in the fuel cell system 31 of the second embodiment, the methanation is used. A CO remover 32c utilizing a reaction is provided. That is, the hydrogen generator 32 is configured by sequentially connecting a reformer 3a, a transformer 3b, and a CO remover 32c. In the methanation reaction, the selective oxidation reaction removes carbon monoxide in the fuel gas by oxidizing it with oxygen in separately supplied selective oxidizing air to form carbon dioxide, whereas the methanation reaction removes carbon monoxide from the hydrogen in the fuel gas. Carbon monoxide is changed into methane and water under a methanation catalyst to remove carbon monoxide in the fuel gas. For this reason, the selective oxidation air path 19 of the fuel cell system 1 of Embodiment 1 does not exist in the fuel cell system 31 of Embodiment 2.

  The hydrogen generator 32 and the fuel cell 2 are connected by a fuel gas path 33. The fuel gas path 33 has one end connected to the CO remover 32c and the other end connected to the anode flow path 2a of the fuel cell 2, and is branched from the bypass path 13 along the way. The fuel gas valve 11 of the first embodiment is the same as the fuel gas path 11 of the fuel cell system 1 in that the fuel inlet valve 14 is provided on the fuel cell 2 side.

  In the fuel cell system 31 according to the second embodiment, the cathode air path 18 is branched at a branch point X with a bleed air path 34 corresponding to the branch air path. The bleed air path 34 is connected to the fuel gas path 33 at a junction Y that is closer to the hydrogen generator 32 than a branch point of the fuel gas path 33 to the bypass path 13. Further, the bleed air path 34 has a pressure loss so that the air supplied from the air blower 17 is divided into the cathode air and the bleed air at the branch point X at a predetermined ratio during the power generation operation of the fuel cell system 31. Considered.

  That is, in the fuel cell system 31 of the second embodiment, the selective oxidization air of the fuel cell system 1 of the first embodiment is replaced with bleed air. In addition, since the selective oxidation air and the bleed air have different required flow rates, the fuel cell system 31 according to the second embodiment is adjusted so that a predetermined flow rate of bleed air is supplied.

  An air flow meter 35 for detecting the flow rate of the air supplied from the air blower 17 is provided on the air blower 17 side upstream of the branch point X of the cathode air path 18. Detect the amount of air supplied. The air flow rate detected by the air flow meter 35 is wired so as to be input to the control unit 36, and the control unit 36 feedback-controls the rotational speed of the air blower 17 based on the air flow rate detected by the air flow meter 35. In this respect, the fuel cell system 1 of the first embodiment is different from the fuel cell system 31 of the second embodiment.

  Hereinafter, the operation of the fuel cell system 31 of the second embodiment will be described focusing on differences from the fuel cell system 1 shown in the first embodiment.

  The hydrogen generator 32 is obtained by replacing the selective oxidizer 3c in the hydrogen generator 3 of the fuel cell system shown in Embodiment 1 with a CO remover 32c using a methanation reaction. The fuel cell system shown in the first embodiment is that the fuel gas is generated from the water vapor and the steam, and the good quality fuel gas having a reduced carbon monoxide concentration is generated by sequentially flowing the transformer 3b and the CO remover 32c. This is the same as the hydrogen generator 3 in FIG.

  Further, during the start-up operation of the fuel cell system 31, while the temperature of each catalyst of the hydrogen generator 32 is not increased to a temperature suitable for performing each reaction, the hydrogen generator 32 supplies the catalyst. Since the fuel gas contains a large amount of carbon monoxide, the temperature of each catalyst of the hydrogen generator 32 reaches a predetermined temperature so that the carbon monoxide does not poison the catalyst of the anode electrode of the fuel cell 2. Further, the first embodiment is also used in that the fuel cell 2 is burned in the burner section 3e via the bypass path 13 until the high-quality fuel gas with reduced carbon monoxide concentration is supplied. This is the same as the fuel cell system 1 of FIG.

  The supply of bleed air to the fuel gas passage 33 via the bleed air passage 34 by the air blower 17 may be started before the fuel gas is supplied to the fuel cell 2, but the fuel of the present embodiment In the battery system, the temperature of each catalyst in the hydrogen generator 32 becomes a temperature suitable for performing each reaction, and then the fuel inlet valve 14 and the fuel outlet valve 15 are opened and at the same time the bypass valve. 16 was closed and fuel gas and bleed air were supplied to the fuel cell 2. Thereby, it is possible to shorten the time for which the air blower 17 is driven during the start-up operation as much as possible, and the energy consumed during the start-up operation of the fuel cell system can be reduced.

  The fuel gas having a reduced carbon monoxide concentration supplied from the hydrogen generator 32 is supplied to the fuel cell 2. The fuel gas is supplied from the air blower 17 during the power generation operation of the fuel cell system 31. A part of the air or all of the air supplied from the air blower 17 before starting the supply of the cathode air to the fuel cell 2 during the start-up operation of the fuel cell system 31 passes through the bleed air path 34. It is mixed. Therefore, even if carbon dioxide in the fuel gas supplied to the fuel cell 2 undergoes a reverse shift reaction by the action of the catalyst provided in the anode electrode of the fuel cell 2 and carbon monoxide is generated, Since carbon monoxide is burned by oxygen, the catalyst of the anode electrode is not poisoned by carbon monoxide. Thereby, the performance of the fuel cell 2 is not lowered, and the performance of the fuel cell system can be prevented from being lowered or deteriorated.

  In the fuel cell system 1 shown in the first embodiment, an air blower is used in which the amount of air supplied from the air blower 17 is always the same depending on the rotation speed of the air blower 17. By controlling the rotational speed of 17 to be kept constant at the predetermined rotational speed, a predetermined flow rate of air is supplied from the air blower, whereas in the fuel cell system 31 of the second embodiment, The difference from the fuel cell system 1 shown in the first embodiment is that the rotational speed of the air blower is controlled based on the air flow detected by the air flow meter 35.

  When starting the supply of the cathode air to the fuel cell 2 during the start-up operation of the fuel cell system 31, the air inlet valve 20 is opened and the experiment is performed in advance as described in the first embodiment. The air blower 17 is driven at the rotational speed obtained by the above and stored in the control unit 36, and the condensed water accumulated in the path through which the cathode air flows is discharged out of the fuel cell system 31, and then the air blower. The rotational speed of 17 is controlled based on the air flow rate detected by the air flow meter 35.

  As a result, the condensed water accumulated in the path through which the cathode air and the cathode exhaust air circulate when the fuel cell system is stopped is used to start the supply of the cathode air to the fuel cell. The power generation operation can be started after discharging to the outside and returning the shunt ratio between the cathode air and the selectively oxidized air to the designed shunt ratio.

  Furthermore, the amount of air supplied from the air blower can be accurately set to a predetermined amount, and the flow rate of the supplied air changes at the same rotation speed with respect to the change in the flow path resistance of the air supply path. Since such an air blower can also be used, it is possible to use a relatively inexpensive and small air blower.

(Embodiment 3)
Next, the configuration of the fuel cell system according to Embodiment 3 of the present invention will be described with reference to the drawings.

  FIG. 4 is a schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 3 of the present invention. In FIG. 4, the same components as those of the fuel cell system 1 shown in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, the fuel cell system 41 according to the third embodiment has substantially the same configuration as the fuel cell system 1 shown in the first embodiment, but the air is in the middle of the selective oxidation air path 19. It differs from the fuel cell system 1 shown in Embodiment 1 in that the flow meter 42 is provided. The flow rate of the selected oxidized air detected by the air flow meter 42 is wired so as to be input to the control unit 43.

  Regarding the operation of the fuel cell system 41 according to the third embodiment, the control unit 43 compares the flow rate of the selectively oxidized air detected by the air flow meter 42 with respect to the fuel cell system 1 shown in the first embodiment. The only difference is that the flow rate of the selected oxidized air at that point in time stored is compared and the rotational speed of the air blower 17 is controlled so that the flow rate of the selected oxidized air becomes the target value. This is the same as the fuel cell system 1 shown in the first embodiment.

  Comparing the flow rate of the cathode air required for the power generation operation of the fuel cell system with the flow rate of the selective oxidation air, the flow rate of the selective oxidation air is smaller and is generally about one tenth of the flow rate of the cathode air. Is. Therefore, in the fuel cell system of the third embodiment, the selective oxidizing air and the cathode air are supplied at an accurate flow rate by adjusting and controlling the rotational speed of the air blower based on the flow rate of the selective oxidizing air with a small flow rate. Therefore, an efficient fuel cell system can be provided.

(Embodiment 4)
Next, the configuration of the fuel cell system according to Embodiment 4 of the present invention will be described with reference to the drawings.

  FIG. 5 is a schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 4 of the present invention. In FIG. 5, the same components as those of the fuel cell system shown in the first to third embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 5, the fuel cell system 51 according to the fourth embodiment has substantially the same configuration as the fuel cell system 1 shown in the first embodiment, but the first embodiment is the following point. Different from the fuel cell system 1 shown in FIG.

  That is, the selective oxidation air path 19 branched from the first branch point Xa in the middle of the cathode air path 18 is wired so as to detect the flow rate of the selective oxidation air and to input the detected flow rate to the control unit 54. An air flow meter 52 is provided. Further, the selective oxidation air path 19 includes a second branch point Xb on the downstream side of the air flow meter 52. One end of a bleed air path 53 is connected to the second branch point Xb, and the other end of the bleed air path 53 is connected to the fuel gas path 11 at a junction Y. The bleed air path 53 has a pressure loss in advance so that a part of the selectively oxidized air supplied via the first branch point Xa is diverted at a predetermined ratio and mixed into the fuel gas path 11. Coordinated and installed.

  The operation of the fuel cell system 51 configured as described above will be described below with a focus on differences from the fuel cell system 1 shown in the first embodiment.

  First, during the power generation operation of the fuel cell system 51, as in the first embodiment, the raw material supply device 4 is driven, and a predetermined amount of the raw material gas is mixed with the water vapor generated by the water vapor generator 3d to be mixed with the hydrogen generator 3. Is supplied to the reformer 3a, and fuel gas is generated. This fuel gas is passed through the transformer 3b and the selective oxidizer 3c in sequence to become a fuel gas having a reduced carbon monoxide concentration. It is supplied to the anode flow path 2 a of the fuel cell 2 through the path 11. Further, by driving the air blower 17, cathode air is supplied to the cathode flow path 2 b of the fuel cell 2 through the cathode air path 18.

  At this time, a part of the air supplied by driving the air blower 17 is diverted at the first branch point Xa and supplied as selective oxidation air to the selective oxidizer 3c via the selective oxidation air path 19. . A part of the selective oxidation air is diverted to the bleed air path 53 at the second branch point Xb, supplied as bleed air to the fuel gas path 11 through the confluence Y, and mixed with the fuel gas to produce fuel. It is supplied to the anode channel 2 a of the battery 2. The rotation speed of the air blower 17 is adjusted by the control unit 54 based on the flow rate of air detected by the air flow meter 52 so that the flow rate detected by the air flow meter becomes a predetermined flow rate. Since the pressure loss of the bleed air path 53 is set so that the air is diverted to the bleed air path 53 at a predetermined ratio, the selective oxidation air path 19 and the bleed air path 53 downstream from the first branch point Xa Is always supplied with a predetermined amount of air with high accuracy. In addition, since the ratio of the air diverted into the cathode air and the selectively oxidized air (and bleed air) by the first branch point Xa is also set in advance to be a predetermined ratio, the fuel cell 2 also A predetermined amount of cathode air is supplied with high accuracy. The rotational speed of the air blower 17 at this time is stored in the control unit 54 as the third rotational speed, but in actuality, it is adjusted from the third rotational speed based on the air flow rate detected by the air flow meter 52. The

  The selective oxidation air supplied to the selective oxidizer 3c is used to oxidize carbon monoxide in the fuel gas supplied from the transformer 3b, and the bleed air is mixed into the fuel gas to be used in the fuel cell 2. The carbon monoxide and oxygen in the bleed air undergo a combustion reaction when carbon monoxide is generated by reverse shift reaction from carbon dioxide in the fuel gas on the anode electrode 2a. This suppresses the poisoning of the anode electrode catalyst by carbon monoxide.

  Further, during the start-up operation of the fuel cell system 51, the temperature of each catalyst in the hydrogen generator 3 becomes a predetermined temperature suitable for performing each reaction, and the bypass path 13 is generated until a high-quality fuel gas is generated. The fuel cell system is the same as the fuel cell system of the other embodiments in that the fuel cell 2 is not supplied and supplied to the fuel cell 2. At this time, the rotation speed of the air blower 17 necessary for supplying the predetermined amounts of the selective oxidation air and the bleed air is set to the first rotation speed. Is adjusted from the first rotational speed.

  When good quality fuel gas starts to be supplied from the hydrogen generator 3, supply of fuel gas to the fuel cell 2 is started, and after a predetermined time has elapsed, the air inlet valve 20 is opened to supply cathode air to the fuel cell 2. Start. At this time, similarly to the fuel cell system 1 of the first embodiment, as shown in FIG. 2, the air inlet valve 20 is opened, and at the same time, the air blower 17 is rotated at a predetermined second speed higher than the third rotational speed. The condensed water accumulated when the fuel cell system is stopped is discharged to the outside of the fuel cell system 51 via the cathode exhaust air passage 21. Then, after the rotational speed of the air blower 17 is lowered to the third rotational speed, the rotational speed of the air blower is controlled based on the flow rate detected by the air flow meter 52. Here, the second rotational speed of the air blower 17 is obtained in advance by experiments and stored in the control unit 54, which is the same as in the first embodiment.

  As described above, in the fuel cell system of the fourth embodiment, since the anode catalyst electrode of the fuel cell 2 can be prevented from being poisoned, the performance of the fuel cell system is reduced or deteriorated. In addition, the flow rates of the selectively oxidized air, the bleed air, and the cathode air are generated again after the start-up operation of the fuel cell system by the condensed water generated when the fuel cell system is stopped. Therefore, it is possible to provide a fuel cell system in which the performance does not deteriorate even if the start and stop are repeated.

(Embodiment 5)
Next, the configuration of the fuel cell system according to Embodiment 5 of the present invention will be described with reference to the drawings.

  FIG. 6 is a schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 5 of the present invention. In FIG. 6, the same components as those of the fuel cell system shown in Embodiments 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 6, the fuel cell system 61 according to the fifth embodiment has substantially the same configuration as the fuel cell system 1 shown in the first embodiment, but the first embodiment is the following point. Different from the fuel cell system 1 shown in FIG.

  That is, the selective oxidation air path 19 branched from the cathode air path 18 and the branch point X is provided with an air flow meter 62 for detecting the flow rate of the selective oxidation air, and further downstream is equivalent to the flow resistance resistance means. An adjustment valve 63 that is a needle valve is provided. The air flow meter 62 is wired so as to detect the flow rate of the selected oxidized air supplied to the selected oxidized air path 19 and input it to the control unit 64, and the adjustment valve 63 can be freely opened by the control unit 64. It is wired so that the pressure loss of the selective oxidation air path 19 can be adjusted.

  The operation of the fuel cell system 61 configured as described above will be described below with a focus on differences from the fuel cell system 1 shown in the first embodiment.

  First, during the power generation operation of the fuel cell system 61, as in the first embodiment, the raw material supply device 4 is driven, and a predetermined amount of the raw material gas is mixed with the water vapor generated by the water vapor generator 3d to be mixed with the hydrogen generator 3. Is supplied to the reformer 3a, and fuel gas is generated. This fuel gas is passed through the transformer 3b and the selective oxidizer 3c in sequence to become a fuel gas having a reduced carbon monoxide concentration. It is supplied to the anode flow path 2 a of the fuel cell 2 through the path 11. Further, by driving the air blower 17, cathode air is supplied to the cathode flow path 2 b of the fuel cell 2 through the cathode air path 18.

  At this time, the air supplied from the air blower 17 is split at a predetermined ratio between the cathode air and the selectively oxidized air at the branch point X. The rotation speed of the air blower 17 is adjusted by the control unit 64 based on the flow rate detected by the air flow meter 62 provided in the selective oxidation air path 19 so that the flow rate of the selective oxidation air becomes a predetermined flow rate. However, at this time, the opening degree of the regulating valve 63 is obtained in advance by experiment and stored in the control unit 64 so that the flow rate of the cathode air supplied to the fuel cell 2 becomes a predetermined flow rate. Is controlled by the control unit 64 as this opening (hereinafter, described as the second opening). Further, the rotational speed of the air blower 17 at this time is stored in the control unit 64 as a third rotational speed, and the flow rate of the selected oxidized air is determined based on the flow rate of the selected oxidized air detected by the air flow meter 62. The rotational speed of the air blower 17 is finely adjusted from the third rotational speed by the control unit 64 so that the flow rate becomes equal to

  During the power generation operation of the fuel cell system 61, the opening degree of the regulating valve 63 is fixed at the second opening degree, which is determined by the electric power necessary for moving the regulating valve 63. This is to prevent the system efficiency from decreasing. However, for example, the cathode air passage 18 is also provided with an air flow meter, and the adjustment valve 63 is based on the values of the air flow meter 62 provided in the selective oxidation air passage 19 and the air flow meter provided in the cathode air passage. And the air blower 17 may be controlled so that the cathode air and the selectively oxidized air have a predetermined flow rate.

  Next, the startup operation of the fuel cell system will be described below with reference to the drawings.

  During the start-up operation of the fuel cell system 61, as in the fuel cell system 1 described in the first embodiment, the temperature of each catalyst of the hydrogen generator 3 becomes a predetermined temperature suitable for performing each reaction, Until a good quality fuel gas is produced, the fuel gas is circulated through the bypass path 13 and is not supplied to the fuel cell 2. When the temperature of the selective oxidation catalyst of the selective oxidizer 3c reaches a temperature suitable for performing the selective oxidation reaction, the control unit 64 makes the opening degree of the regulating valve 63 smaller than the second opening degree, which will be described later. After controlling to the opening degree, the air blower 17 is driven at a predetermined first rotational speed, and supply of the selective oxidizer air to the selective oxidizer 3c is started. At this time, the control unit 64 finely adjusts the rotational speed of the air blower 17 from the first rotational speed based on the flow rate detected by the air flow meter 62 so that the amount of the selectively oxidized air becomes a predetermined flow rate. .

  When the temperature of each catalyst in the hydrogen generator 3 becomes a temperature suitable for performing each reaction and the supply of high-quality fuel gas from the hydrogen generator 3 is started, the fuel cell system 1 of the first embodiment. Similarly, the supply of fuel gas to the fuel cell 2 is started, and after a predetermined time has elapsed, the air inlet valve 20 is opened and the supply of cathode air to the fuel cell 2 is started.

  Here, FIG. 7 is a timing chart showing the operation of the main components and the changes in the flow rates of the cathode air and the selective oxidation air before and after the supply of the cathode air to the fuel cell 2 is started. 7A shows the closing and opening of the air inlet valve 20, FIG. 7B shows the rotation speed of the air blower 17, FIG. 7C shows the change in the opening degree of the regulating valve 63, and FIG. The flow rate of the cathode air, (e), shows the change in the flow rate of the selectively oxidized air.

  As shown in FIG. 7, when the supply of cathode air to the fuel cell 2 is started, first, the air inlet valve 20 is opened, and at the same time, the rotational speed of the air blower 17 is set to be larger than the third rotational speed. The condensed water accumulated in the path through which the cathode air and the cathode exhaust air circulate is discharged out of the fuel cell system 61 through the cathode exhaust air path 21. Here, the second rotational speed is obtained in advance by an experiment and stored in the control unit 64 as in the first embodiment.

  Further, at this time, the regulating valve 63 causes the pressure loss of the selective oxidation air path 19 from the second opening degree for the cathode air and the selective oxidation air to be diverted at a predetermined ratio during the power generation operation of the fuel cell system 61. The first opening is increased. For this reason, when the rotational speed of the air blower 17 is set to the second rotational speed, the flow rate of the selective oxidation air increases in the fuel cell system 1 of Embodiment 1 as shown in FIG. In the fuel cell system 61 of the fifth embodiment, the amount of change in the selective oxidized air flow rate can be reduced. Further, the first opening degree of the regulating valve 64 is such that the flow rate of the selective oxidation air does not deviate from the predetermined flow rate when the air blower 17 is driven at the second rotational speed at the same time as the air inlet valve 20 is opened. Is obtained in advance by experiment and stored in the control unit 64, so that when the air inlet valve 20 is opened, as shown in FIG. Is possible. However, the amount of condensed water that accumulates in the path through which the cathode air and cathode exhaust air circulate may vary depending on the power generation operation or stop state of the fuel cell system. May deviate from quantitative. However, since the amount of deviation can be reduced, the flow rate of the selective oxidation air becomes larger than a predetermined amount, the catalyst temperature of the selective oxidizer 3c increases, and the efficiency of the fuel cell system decreases. Can be suppressed.

  Next, when the condensed water accumulated in the path through which the cathode air and the cathode exhaust air circulate is discharged out of the fuel cell system 61 via the cathode exhaust air path 21, the controller 64 causes the air blower 17 to At the same time as reducing the rotational speed to the third rotational speed, the opening degree of the regulating valve 63 is controlled to the second opening degree, and the power generation operation of the fuel cell system is started. In FIG. 7, the rotation speed of the air blower 17 is changed from the second rotation speed to the third rotation speed, and the opening degree of the adjustment valve 63 is changed from the first opening degree to the second opening degree over a predetermined time. However, since the adjustment valve 63 is a needle valve, it takes time to change the opening, and the rotational speed of the air blower 17 is gradually increased according to the change in the opening of the adjustment valve 63. It is changing.

  As described above, according to the fuel cell system of the fifth embodiment, it is possible to supply the cathode air and the washing oxidized air with one air blower, and from the air blower with one air flow meter. Since the flow rates of the cathode air and the selectively oxidized air to be supplied can be accurately controlled, the configuration of the fuel cell system can be simplified, and the start-up operation, power generation, and stop operation of the fuel cell system can be simplified. Even when it is repeated, it is possible to suppress the selective oxidation air and cathode air supplied from the air blower from deviating from a predetermined amount, and to prevent the performance of the fuel cell system from being deteriorated.

(Embodiment 6)
Next, the configuration of the fuel cell system according to Embodiment 6 of the present invention will be described with reference to the drawings.

  FIG. 8 is a schematic diagram schematically showing the configuration of the fuel cell system according to Embodiment 6 of the present invention. In FIG. 8, the same components as those of the fuel cell system shown in the first to fifth embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, the fuel cell system 71 according to the sixth embodiment has substantially the same configuration as the fuel cell system 1 shown in the first embodiment, but the first embodiment is the following point. Different from the fuel cell system 1 shown in FIG.

  That is, similarly to the fuel cell system 41 shown in the third embodiment, an air flow meter 42 is provided in the selective oxidation air path 19. Further, a diversion valve 72 is provided as a diversion ratio adjusting means at a location corresponding to the branch point X between the cathode air path 18 and the selective oxidation air path 19.

  The diversion valve 72 is controlled by the control unit 73 and can arbitrarily change the diversion ratio for diverting the air supplied from the air blower 17 into the cathode air and the selective oxidation air. Further, the diversion valve 72 is controlled such that all of the air supplied from the air blower 17 is supplied to the selective oxidation air path 19, thereby blocking the supply of cathode air to the fuel cell 2. Yes, it can also serve as a cathode air supply blocking means at the same time. Therefore, the fuel cell system 71 of Embodiment 6 is not provided with the air inlet valve 20 separately. Thereby, the configuration of the fuel cell system can be simplified.

  The operation of the fuel cell system 71 configured as described above will be described below with a focus on differences from the fuel cell system 1 shown in the first embodiment.

  First, during the power generation operation of the fuel cell system 71, as in the first embodiment, the raw material supply device 4 is driven, and a predetermined amount of the raw material gas is mixed with the water vapor generated by the water vapor generator 3d to be mixed with the hydrogen generator 3. Is supplied to the reformer 3a, and fuel gas is generated. This fuel gas is passed through the transformer 3b and the selective oxidizer 3c in sequence to become a fuel gas having a reduced carbon monoxide concentration. It is supplied to the anode flow path 2 a of the fuel cell 2 through the path 11. Further, cathode air is supplied to the cathode flow path 2 b of the fuel cell 2 by the air blower 17 via the cathode air path 18.

  At this time, the control unit 72 feedback-controls and adjusts the rotation speed of the air blower 17 so that the flow rate of the selective oxidation air becomes a predetermined flow rate based on the flow rate of the selective oxidation air detected by the air flow meter 42. However, the control unit 72 controls the branch valve 72 in advance so that when the flow rate of the selective oxidation air is a predetermined flow rate, the opening of the diversion valve 72 is set to a predetermined flow rate so that the cathode air has a predetermined flow rate. Keep the opening. Thereby, the flow rate of the selective oxidation air can be accurately controlled, but in addition, the flow rate of the cathode air is also accurately controlled.

  Further, since the operation at the time of the stop operation of the fuel cell system is the same as that of the other embodiments, the description thereof is omitted here.

  Next, the startup operation of the fuel cell system will be described.

  During the start-up operation of the fuel cell system 71, as in the fuel cell system 1 shown in the first embodiment, the temperature of each catalyst of the hydrogen generator 3 becomes a predetermined temperature suitable for performing each reaction, Until a good quality fuel gas is produced, the fuel gas is circulated through the bypass path 13 and is not supplied to the fuel cell 2.

  When the temperature of the selective oxidation catalyst of the selective oxidizer 3c reaches a temperature suitable for performing the selective oxidation reaction, the control unit 73 drives the air blower 17 to generate the selective oxidized air having a predetermined flow rate through the selective oxidation air path 19. Supply to the selective oxidizer 3c is started. At this time, the diverter valve 72 is adjusted so that all the air supplied by the air blower 17 is supplied to the selective oxidizer 3c. Further, the control unit 73 feedback-controls the rotational speed of the air blower 17 based on the air flow rate detected by the air flow meter 42 so that a predetermined flow rate of air is supplied to the selective oxidizer 3c.

  When the temperature of each catalyst in the hydrogen generator 3 becomes a temperature suitable for performing each reaction and the supply of high-quality fuel gas from the hydrogen generator 3 is started, the fuel cell system 1 of the first embodiment. In the same manner, supply of fuel gas to the fuel cell 2 is started. After the elapse of a predetermined time from the start of the supply of fuel gas to the fuel cell 2, the opening degree of the diversion valve 72 is changed by the control unit 73, and the air supplied from the air blower 17 becomes the fuel cell 2 and the selective oxidizer 3c. And be supplied to.

  At this time, the rotation speed of the air blower 17 is controlled so as to supply more air than the total amount of the cathode air and the selective oxidation air necessary for the power generation described above. Further, after the predetermined time has elapsed, the rotational speed of the air blower is decreased, and based on the flow rate of the selective oxidation air detected by the air flow meter 42 so that the cathode air and the selective oxidation air are respectively supplied at a predetermined flow rate, The rotational speed of the air blower 17 is feedback-controlled so that the flow rate of the selective oxidation air becomes a predetermined flow rate. Thereby, the flow rate of the selective oxidation air can be accurately controlled.

  Here, the operation of main components before and after the start of the supply of cathode air to the fuel cell 2 and the behavior of the flow rates of the cathode air and the selective oxidation air will be described with reference to the drawings.

  FIG. 9 is a timing chart showing the operation of the main components and the behavior of the flow rates of the cathode air and the selective oxidation air associated therewith. In FIG. 9, (a) shows the opening degree of a branch valve 72 described later, (b) shows the rotational speed of the air blower 17, (c) shows the flow rate of the cathode air, and (d) shows the flow rate of the selective oxidation air. Each is shown. Here, the opening degree of the diversion valve 72 is indicated by the vertical axis in FIG. 9A, and all the air supplied by the air blower 17 when the opening degree is 0 flows to the selective oxidizing air path 19 side. In the description, it is assumed that the ratio of the air supplied from the air blower 17 to the fuel cell 2 as cathode air increases.

  As shown in FIG. 9, when the supply of cathode air to the fuel cell 2 is started, first, the opening degree of the diversion valve 72 is increased, and at the same time, the rotational speed of the air blower 17 is increased. Here, before the supply of cathode air to the fuel cell 2 is started, the rotational speed of the air blower 17 when supplying air only to the selective oxidizer 3c is determined for convenience (that is, precisely by feedback control). The number is finely adjusted and is not constant, but for the sake of simplicity, it is treated as a constant rotational speed.) The first rotational speed is used, and the rotational speed of the air blower 17 during power generation is set to the first for convenience. Assuming that the rotation speed is 3, the rotation speed of the air blower 17 when starting the supply of cathode air to the fuel cell 2 is controlled to be a second rotation speed higher than the third rotation speed. As a result, more air than the first predetermined flow rate, which is the flow rate of the cathode air necessary for power generation, flows through the fuel cell 2.

  Here, the second rotational speed of the air blower 17 is obtained by conducting experiments in advance in the same manner as in the other embodiments, by condensing the condensed water collected while the fuel cell system 71 is stopped in the path through which the cathode air flows through the cathode exhaust air. The flow rate that can be discharged out of the fuel cell system 71 via the path 21 is obtained as the rotation speed of the air blower 17 supplied to the cathode air path 18 downstream of the branch valve 72, and the control section 73 receives the second rotation speed. I will remember it.

  Thereby, while the air blower 17 is driven at the second rotational speed, the condensed water accumulated in the path through which the cathode air flows is discharged out of the fuel cell system 71 and the pressure loss is normal. Return to value. Thereafter, the rotational speed of the air blower 17 is lowered to the third rotational speed, and the rotational speed of the air blower 17 is feedback-controlled based on the flow rate of the selective oxidized air detected by the air flow meter 42 so that the flow rate of the selective oxidized air is reduced. Control to achieve a predetermined flow rate. At this time, since the pressure loss of the path through which the cathode air circulates returns to normal, the diversion ratio in the diversion valve 72 is as expected. Therefore, by accurately controlling the flow rate of the selective oxidation air, the cathode The air flow rate is also accurately controlled.

  As described above, in the fuel cell system 71 of the sixth embodiment, even when condensed water has accumulated in the path through which the cathode air circulates when the fuel cell system is stopped, the fuel cell system is started again and the fuel cell system 71 When starting to supply cathode air to the battery, it is possible to start power generation after discharging condensed water with the air supplied from the air blower to the outside of the fuel cell system. Even if the stop operation is repeated, the performance of the fuel cell system does not deteriorate or the deterioration is not accelerated.

  In the fuel cell system 71 of the sixth embodiment, a branch valve is provided at a branch point between the cathode air path and the selective oxidation air path that is a branch air path as a diversion ratio adjusting means. A needle valve having a closing function may be provided. In this case, during the start-up operation of the fuel cell system, before starting the supply of cathode air to the fuel cell, the needle valve is closed and all the air supplied from the air blower is supplied to the selective oxidizer. Thus, by releasing the needle valve by a predetermined opening when the supply of cathode air to the fuel cell is started, the same effect as the fuel cell system 71 of the sixth embodiment using the shunt valve is obtained. It is possible to obtain.

  Further, in the fuel cell system 71 of the sixth embodiment, as described above, the shunt valve that is the shunt ratio adjusting means is configured to simultaneously serve as the cathode air supply shut-off means. Similarly to this embodiment, an on-off valve may be separately provided as a cathode air supply shut-off means in the cathode air path, and supply of the cathode air may be started by opening the on-off valve.

  Further, in the fuel cell system in which the on / off valve is further provided in the cathode air path of the fuel cell system, the supply of cathode air to the fuel cell is started in the same manner as in the fuel cell system 61 described in the fifth embodiment. It is possible to keep the flow rate of the selective oxidation air substantially constant before and after.

  That is, when supplying air only to the selective oxidizer in the initial stage of the start-up operation of the fuel cell system, the opening of the shunt valve is set to a first opening described later with the on-off valve closed, and the fuel is When supplying cathode air to the battery, the on / off valve of the cathode air path is released and at the same time the condensed water accumulated in the path through which the cathode air flows is discharged out of the fuel cell system. The second rotation speed is controlled. When the second rotational speed of the air blower is obtained in advance by experiments, at the same time, the opening of the shunt valve is determined so that the flow rate of the selective oxidizing air does not deviate from the predetermined flow rate before and after the rotational speed of the air blower is increased. The first opening of the valve is used. When the condensed water accumulated in the path through which the cathode air circulates is discharged out of the fuel cell system, the rotation speed of the air blower is reduced to the third rotation speed, and the opening of the shunt valve is increased to selectively oxidize the cathode air and the cathode air. Air is supplied at a predetermined flow rate.

  As a result, the flow rate of the selective oxidation air can be suppressed before and after the cathode air is supplied to the fuel cell, and the condensed water can flow into the path through which the cathode air flows while the fuel cell system is stopped. Even if it has accumulated, the start-up operation of the fuel cell system is performed again, and when the supply of cathode air to the fuel cell is started, the condensed water can be discharged out of the fuel cell system by the cathode air. It is possible to accurately supply a predetermined amount of the selective oxidized air. Therefore, it is possible to suppress the performance of the fuel cell system from being reduced or the deterioration from being accelerated with a simple configuration.

  As described above, the fuel cell system according to the present invention can be applied to the use of a fuel cell system in which a hydrocarbon-based raw material such as natural gas or LPG is steam-reformed.

1, 31, 41, 51, 61, 71 Fuel cell system 2 Fuel cell 2a Anode flow path 2b Cathode flow path 3, 32 Hydrogen generator 3a Reformer 3b Transformer 3c Selective oxidizer 3d Steam generator 3e Burner section 3f Temperature sensor 4 Raw material supply device 5 Raw material gas supply path 6 Process water supply pump 7 Process water tank 8 Water vapor supply path 9 Combustion air fan 10 Combustion air path 11, 33 Fuel gas path 12 Off gas path 13 Bypass path 14 Fuel inlet valve 15 Fuel Out valve 16 Bypass valve 17 Air blower 18 Cathode air path 19 Selective oxidation air path 20 Air inlet valve 21 Cathode exhaust air path 22, 36, 43, 54, 64 Control unit 32c CO remover 34, 53 Bleed air path 35, 42 , 52, 62 Air flow meter 63 Regulating valve X, Xa, Xb Branch Y confluence

Claims (12)

A fuel cell that generates power using fuel gas and air;
A hydrogen generator having a reforming section that generates hydrogen-rich fuel gas from raw material and water;
A fuel gas path through which the fuel gas generated by the hydrogen generator is circulated to the fuel cell;
Air supply means for supplying air;
A cathode air path for circulating the air supplied from the air supply means to the fuel cell;
A branched air path that branches from the cathode air path, and that circulates air to at least one of the hydrogen generator and the fuel gas path;
A cathode air supply blocking means for supplying or blocking air to the fuel cell disposed in the cathode air path;
When starting the supply of air to the fuel cell, first, the cathode air supply blocking means is opened to control the supply of air to the fuel cell, and the air supplied to the fuel cell is the first. And a control unit for controlling the air supply means so that the air supplied to the fuel cell has a first predetermined flow rate. Fuel cell system. The flow rate detection means for detecting the flow rate of the air supplied by the air supply means is further provided, and the control unit controls the air supply means based on the air flow rate detected by the flow rate detection means. Item 4. The fuel cell system according to Item 1. The flow rate detecting means is an air flow rate detecting means for detecting a flow rate of air supplied to at least one of the hydrogen generator and the fuel gas path provided in the branch air path, and the control unit is an air flow rate detecting means. The fuel cell system according to claim 2, wherein the air supply means is controlled based on an air flow rate detected by the fuel cell. A diversion ratio adjusting means for adjusting a ratio of distributing the air supplied by the air supply means to the cathode air path and the branch path, a branch point between the cathode air path and the branch air path, or the cathode air path The fuel cell system according to any one of claims 1 to 3, wherein the fuel cell system is provided in any one of the branched air paths. 5. The fuel cell system according to claim 4, wherein the diversion ratio adjusting means is a diversion valve provided at a branch point between the cathode air path and the branch path. 5. The fuel cell system according to claim 4, wherein the diversion ratio adjusting unit is a channel resistance variable unit configured to change a channel resistance of the cathode air path provided in the cathode air path. 5. The fuel cell system according to claim 4, wherein the diversion ratio adjusting unit is a channel resistance variable unit that changes a channel resistance of the branch air path provided in the branch air path. 5. The control unit controls the diversion ratio adjusting unit so that the flow rate of air supplied to the branch air path does not change before and after the supply of cathode air to the fuel cell is started. 8. The fuel cell system according to any one of items 1 to 7. The fuel cell system according to claim 5 or 6, wherein the diversion ratio adjusting means also serves as the cathode air supply cutoff means. The hydrogen generator further includes a reforming unit that generates a hydrogen-rich fuel gas from a raw material and water, and a selective oxidation unit that removes carbon monoxide in the fuel gas generated in the reforming unit, The fuel cell system according to any one of claims 1 to 9, wherein the branch air path is a selective oxidation air path for allowing air to flow through the selective oxidation unit. 10. The bleed air path according to claim 1, wherein the branch air path is a bleed air path through which air is circulated through the fuel gas path, mixed into the fuel gas, and supplied to the fuel cell. The fuel cell system according to item. There is a bleed air path that branches from the selective oxidation air path, distributes a part of the air supplied to the selective oxidation air path to the fuel gas path, mixes it with the fuel gas, and supplies it to the fuel cell. The flow control device according to claim 10, further comprising a flow rate adjusting unit configured to adjust a flow rate of air supplied to the selective oxidation unit and a flow rate of air supplied to the fuel gas path to a predetermined ratio in the bleed air path. Fuel cell system.

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