JP2019046706A - Fuel cell system - Google Patents

Abstract

To extend a usage period of a chemical filter while preventing an increase in the size and cost of the chemical filter.SOLUTION: A fuel cell system equipped with a fuel cell that generates electricity based on fuel gas and air includes a chemical filter that can remove an impurity in the air by chemical reaction, an air flow path that has a chemical filter flow path provided with the chemical filter and a bypass flow path bypassing the chemical filter and through which air is directed to the fuel cell through either the chemical filter flow path or the bypass flow path, a blower provided in the air flow path to supply air to the fuel cell by driving, and a switching valve that is provided in the air flow path and switches a flow path through which air toward the fuel cell passes to either the chemical filter flow path or the bypass flow path.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell system.

  Conventionally, this type of fuel cell system includes a fuel cell that generates electricity based on fuel gas and air, and is provided with a chemical filter that can adsorb and remove impurities in air supplied to the fuel cell by a chemical reaction. What has been proposed. For example, in the fuel cell system of Patent Document 1, a first filter including a fiber treated with an acidic buffer solution to adsorb a basic gas such as ammonia gas, and an oxidizing gas such as sulfur oxide SOx or nitrogen oxide NOx A second filter in which a weakly alkaline metal salt is supported on activated carbon mixed paper for adsorbing carbon dioxide, and a third filter in combination with a third filter including fibers supporting metal zeolite for adsorbing VOC gas such as organic solvent It is used. Further, in the fuel cell system of Patent Document 2, a chemical combining an activated carbon filter for adsorbing an oxidation gas such as sulfur oxide SOx or nitrogen oxide NOx and a charge filter for adsorbing dust of about several μm It uses a filter.

JP, 2011-233381, A JP, 2013-134860, A

  The chemical filter used in the fuel cell system described above is required to have a relatively long service life, such as about a decade, so as not to require frequent replacement. However, in order to realize such a long-term use period, a larger adsorption layer is required as an adsorption layer for adsorbing impurities, which leads to an increase in size and cost.

  The main object of the present invention is to extend the usage period of a chemical filter while preventing the size increase and cost increase of the chemical filter.

  The present invention adopts the following means in order to achieve the above-mentioned main objects.

  The fuel cell system according to the present invention is a fuel cell system including a fuel cell that generates electric power based on fuel gas and air, and is provided with a chemical filter capable of removing impurities in the air by a chemical reaction, and the chemical filter An air flow path for directing air to the fuel cell through either the chemical filter flow path or the bypass flow path, and a bypass flow path bypassing the chemical filter; The chemical filter flow path and the bypass flow are provided in the air flow path, and a blower that supplies air to the fuel cell by driving, and a flow path that is provided in the air flow path and through which air toward the fuel cell passes The gist of the present invention is to provide a switching valve for switching to any of the paths.

  In the fuel cell system of the present invention, the blower and the flow path through which the air passes are the chemical filter flow path and the bypass in the air flow path having the chemical filter flow path provided with the chemical filter and the bypass flow path bypassing the chemical filter. A switching valve for switching to any of the flow paths is provided. For this reason, by passing the air supplied to the fuel cell to the bypass flow path, it is not always necessary to pass the chemical filter. Therefore, the intermittent use of the chemical filter can be enabled and the accumulation of impurities in the chemical filter can be suppressed. Therefore, while the size increase and cost increase of the chemical filter are prevented, the use period of the chemical filter is extended. Can be

  The fuel cell system according to the present invention may further include a control device that controls the switching valve such that air supplied to the fuel cell intermittently passes through the chemical filter flow path. In this case, since the intermittent use of the chemical filter is realized by the control of the switching valve, it is possible to extend the usage period of the chemical filter by a simple process.

  In the fuel cell system according to the present invention, the fuel cell system further comprises temperature acquisition means for acquiring the temperature of the fuel cell, and the control device is configured to allow air to pass through the bypass channel when the temperature of the fuel cell is lower than a predetermined temperature. The switching valve may be controlled, and when the temperature of the fuel cell exceeds the predetermined temperature, the switching valve may be controlled such that air passes through the chemical filter channel. In this case, since the temperature of the fuel cell is equal to or lower than the predetermined temperature, even if air not passing through the chemical filter is supplied to the fuel cell, the reaction by the impurities reaching the fuel cell is not promoted and there is little risk of progress of deterioration. In some cases, chemical filters may not be used. Therefore, it is possible to extend the usage period of the chemical filter while suppressing the influence of not letting air pass through the chemical filter.

  In the fuel cell system according to the present invention, the fuel cell system further comprises flow rate acquiring means for acquiring the flow rate of air passing through the air flow path, and the control unit is configured to control The switching valve is controlled to pass through the bypass flow path, and when the flow rate of air in the air flow path exceeds the predetermined flow rate, the switching valve is controlled to pass air through the chemical filter flow path It is also good. In this case, since the flow rate of the air flowing to the fuel cell is equal to or less than the predetermined flow rate, the absolute amount of impurities reaching the fuel cell is small even if air not passing through the chemical filter is supplied to the fuel cell. If you do not have a chemical filter, you may not want to use a chemical filter. Therefore, it is possible to extend the usage period of the chemical filter while suppressing the influence of not letting air pass through the chemical filter.

  In the fuel cell system of the present invention, the fuel cell system further comprises an output acquiring means for acquiring a voltage or current as an output of power generation of the fuel cell, and the control device is configured to bypass the air when the voltage or the current is less than a predetermined value. The switching valve may be controlled to pass through the flow path, and the switching valve may be controlled such that air passes through the chemical filter flow path when the voltage or the current exceeds the predetermined value. In this case, even if air not passing through the chemical filter is supplied to the fuel cell because the voltage or current generated by the fuel cell is below the predetermined value, the reaction by the impurities reaching the fuel cell is not promoted and the deterioration progresses The chemical filter may not be used when the risk of Therefore, it is possible to extend the usage period of the chemical filter while suppressing the influence of not letting air pass through the chemical filter.

  In the fuel cell system according to the present invention, the fuel cell is a solid oxide fuel cell, and the fuel cell system includes a temperature acquiring unit for acquiring the temperature of the fuel cell, and the control device stops operation of the fuel cell. The switching valve is controlled such that the fuel cell is cooled by the air passing through the chemical filter flow path until the temperature of the fuel cell falls below a predetermined temperature, and the temperature of the fuel cell falls below the predetermined temperature After that, the switching valve may be controlled such that the fuel cell is cooled by the air passing through the bypass flow passage. Since the solid oxide fuel cell is reacted at a relatively high temperature and easily degraded by impurities such as sulfur in the air, it is desirable to remove the impurities in the air by a chemical filter. In addition, when stopping the operation of the fuel cell, it is necessary to flow in a relatively large amount of air in order to cool the fuel cell as quickly as possible. For this reason, the fuel cell is appropriately controlled while suppressing deterioration of the fuel cell by switching from the chemical filter passage to the bypass passage based on the temperature of the fuel cell falling below the predetermined temperature while stopping the operation. It becomes possible to cool.

  In the fuel cell system according to the present invention, the fuel cell system further comprises a physical filter that physically removes impurities in the air without chemical reaction, wherein the physical filter is provided in the bypass flow path or the bypass flow path It is good also as what is provided in the said air flow path so that the air which passed may pass. In this way, even when the chemical filter is not used, the impurities in the air can be physically removed, so it is possible to suppress the possibility of the progress of deterioration due to the air not being allowed to pass through the chemical filter.

FIG. 1 is a configuration diagram showing an outline of a configuration of a fuel cell system 10; FIG. 5 is a configuration diagram showing an outline of a configuration of an air supply device 50. It is a flowchart which shows an example of a switching process during start / stop. 5 is a flowchart illustrating an example of a power generation switching process routine. It is a flowchart which shows the switch processing routine during start / stop of a modification. It is a block diagram which shows the outline of a structure of the air supply apparatus 150 of a modification. It is a block diagram which shows the outline of a structure of the air supply apparatus 250 of a modification.

  Next, an embodiment of the present invention will be described.

  FIG. 1 is a block diagram showing the outline of the configuration of a fuel cell system 10 of the present embodiment, and FIG. 2 is a block diagram showing the outline of the configuration of an air supply device 50. As shown in FIG. As shown in FIG. 1, the fuel cell system 10 according to the present embodiment has a fuel cell stack 36 that receives supply of a fuel gas containing hydrogen and an oxidant gas (air) containing oxygen to generate electricity by an electrochemical reaction. It includes a power generation unit 20, a hot water supply unit 100 having a hot water storage tank 101 for recovering heat and generating heat generated by the power generation of the power generation unit 20, and a control device 80 for controlling the entire system.

  The power generation unit 20 evaporates the reforming water to generate steam and preheats the raw fuel gas (for example, natural gas and LP gas), a fuel gas containing hydrogen from the raw fuel gas and the steam, Power generator module 30 including a reformer 33 for producing the fuel gas and a fuel cell stack 36 for generating power with fuel gas and air, and a raw fuel gas supply device for supplying the raw fuel gas to the vaporizer 32. 40, an air supply device 50 for supplying air to the fuel cell stack 36, a reforming water supply device 65 for supplying reforming water to the vaporizer 32, and exhaust heat recovery for recovering exhaust heat generated by the power generation module 30 And an apparatus 70. These are accommodated in the housing 22. An air inlet 22a and an air outlet 22b are provided in the housing 22, and a ventilation fan 24 for taking in outside air and ventilating the inside of the housing 22 is provided in the vicinity of the air inlet 22a, and the air outlet 22b In the vicinity, a combustible gas sensor 95 for detecting a leak of combustible gas is provided.

  The vaporizer 32, the reformer 33, and the fuel cell stack 36 that constitute the power generation module 30 are housed in a box-shaped module case 31 formed of a heat insulating material. In the module case 31, a combustion unit 34 for supplying the heat necessary for starting the fuel cell stack 36, generation of water vapor in the vaporizer 32, and steam reforming reaction in the reformer 33 is provided. The fuel off gas (anode off gas) and the oxidant off gas (cathode off gas) that have passed through the fuel cell stack 36 are supplied to the combustion unit 34, and the mixed gas is ignited and burned by the ignition heater 35 to obtain a fuel cell. The stack 36, the vaporizer 32, and the reformer 33 are heated. The combustion exhaust gas generated by the combustion of the fuel off gas and the oxidant off gas is supplied to the heat exchanger 72 via the combustion catalyst 37. The combustion catalyst 37 is an oxidation catalyst that causes the fuel gas remaining in the combustion unit 34 to burn again using the catalyst.

  The exhaust heat recovery device 70 has a circulation pipe 71 that connects the heat exchanger 72 to which the combustion exhaust gas is supplied from the power generation module 30 and the hot water storage tank 101 for storing the hot water storage to form a hot water circulation path. A circulating pump 73 is provided in the circulating pipe 71, and by driving the circulating pump 73, the stored hot water is heated by heat exchange between the stored hot water and the combustion exhaust gas by the heat exchanger 72, and the stored hot water is heated. The water is stored in the hot water storage tank 101. The heat exchanger 72 is connected to the reforming water tank 67 via the condensed water supply pipe 76 and to the outside air via the exhaust gas discharge pipe 77. Water supplied to the heat exchanger 72 and condensed by heat exchange with the stored hot water passes through a water purifier (not shown) and is recovered to the reforming water tank 67. Further, the water and the remaining gas components which are not condensed are discharged to the outside air through the exhaust gas discharge pipe 77.

  The raw fuel gas supply device 40 has a raw fuel gas supply pipe 41 connecting the gas supply source 1 and the carburetor 32. The raw fuel gas supply pipe 41 is provided with raw fuel gas supply valves (electromagnetic valves) 42 and 43, an orifice 44, a raw fuel gas pump 45, and a desulfurizer 46 in this order from the gas supply source 1 side. By driving the raw fuel gas pump 45 with the supply valves 42 and 43 open, the raw fuel gas from the gas supply source 1 passes through the desulfurizer 46 and is supplied to the vaporizer 32. The raw fuel gas supplied to the vaporizer 32 is supplied to the reformer 33 through the vaporizer 32 and is reformed into fuel gas. The raw fuel gas supply valves 42 and 43 are double valves connected in series. The desulfurizer 46 removes sulfur contained in the raw fuel gas, and for example, a normal temperature desulfurization system in which a sulfur compound is adsorbed on an adsorbent such as zeolite and removed may be employed. Further, a pressure sensor 47 for detecting the pressure of the raw fuel gas in the raw material gas supply pipe 41 is provided between the raw fuel gas supply valve 43 and the orifice 44 of the raw fuel gas supply pipe 41. Between the raw fuel gas pump 45 and the raw fuel gas pump 45, a flow rate sensor 48 for detecting the flow rate per unit time of the raw fuel gas flowing through the raw material gas supply pipe 41 is provided.

  As shown in FIGS. 1 and 2, the air supply device 50 has an air supply pipe 51 connecting the outside air and the fuel cell stack 36. The air supply pipe 51 includes a chemical filter flow path 51a provided with a chemical filter 52, and a bypass flow path 51b provided in parallel with the chemical filter flow path 51a and bypassing air without passing the chemical filter 52. It is comprised by the supply flow path 51c which supplies the air introduce | transduced through either of the chemical filter flow path 51a and the bypass flow path 51b to the fuel cell stack 36. As shown in FIG. The air supply device 50 also includes a three-way valve 53 selectively connecting one of the chemical filter flow path 51a and the bypass flow path 51b to the supply flow path 51c, and a physical filter 54 provided in the supply flow path 51c. And an air blower 55 provided on the downstream side of the physical filter 54 in the supply flow passage 51c. The physical filter 54 may be provided downstream of the air blower 55. Further, on the downstream side of the air blower 55, a flow rate sensor 56 for detecting the flow rate of air flowing through the supply flow path 51c (air supply pipe 51) per unit time is provided in the supply flow path 51c. The chemical filter 52 is removable by adsorbing impurities in the air by a chemical reaction (chemical bond), and for example, activated carbon, activated carbon fiber, ion exchange fiber or the like is used as a filter medium. The physical filter 54 can be removed by physically collecting and adsorbing impurities in the air without performing a chemical reaction, and exemplifies a so-called HEPA filter using, for example, glass fibers as a filter medium. Can. The chemical filter 52 may be capable of adsorption by physical collection in addition to adsorption by a chemical reaction, for example, by wrapping granular activated carbon in a non-woven fabric. Chemical filters tend to be higher in ability to remove sulfur oxides SOx, nitrogen oxides NOx, etc. than physical filters, and cost is also high.

  The reforming water supply device 65 has a reforming water supply pipe 66 connecting the reforming water tank 67 storing the reforming water and the vaporizer 32. A reforming water pump 68 is provided in the reforming water supply pipe 66, and by driving the reforming pump 68, the reforming water of the reforming water tank 67 is supplied to the vaporizer 32. The reformed water supplied to the vaporizer 32 is converted to steam by the vaporizer 32 and used for the steam reforming reaction in the reformer 33.

The fuel cell stack 36 includes a solid electrolyte comprising an oxygen ion conductor, an anode electrode provided on one side of the solid electrolyte, and a cathode electrode provided on the other side of the solid electrolyte. The cells are configured as stacked, and power is generated by an electrochemical reaction between hydrogen in the fuel gas supplied to the anode electrode and oxygen in the air supplied to the cathode electrode. Since this electrochemical reaction is performed at a relatively high temperature (for example, about 600 to 700 ° C.), if the air contains an impurity such as sulfur oxide SOx or nitrogen oxide NOx, the chemical reaction between the impurity and the electrode The reaction is facilitated to cause deterioration of each electrode of the fuel cell stack 36. For example, the sulfur contained in SO ₂ in the air reacts with a metal such as Sr contained in the cathode electrode to form a sulfate, whereby the cathode electrode is denatured and the activity is degraded, etc. It will occur. In order to remove these impurities, the air supply pipe 51 is provided with the chemical filter 52 described above. Further, the physical filter 54 described above is provided in the air supply pipe 51 in order to remove physical impurities such as dust and pollen whose particle diameter is larger than the impurities to be removed by the chemical filter 52.

  Further, the fuel cell stack 36 is provided with a temperature sensor 91 for detecting the temperature (fuel cell temperature T) of the fuel cell stack 36. The power line 3 from the commercial power source 2 to the load 4 is connected to the output terminal of the fuel cell stack 36 via a power conditioner 78 including a DC / DC converter and an inverter, and DC power from the fuel cell stack 36 Is added to AC power from the commercial power source 2 through voltage conversion and DC / AC conversion by the power conditioner 78 and supplied to the load 4. The power line connected to the output terminal of the fuel cell stack 36 is provided with a current sensor 92 for detecting the output current I of the fuel cell stack 36, and between the output terminals of the fuel cell stack 36, the fuel cell stack A voltage sensor 93 for detecting the output voltage (generated voltage) V of 36 is provided. The power conditioner 78 may be provided with a power sensor that detects the power generated by the fuel cell stack 36. A power supply substrate 79 is connected to the power line branched from the power conditioner 78. The power supply substrate 79 includes the ventilation fan 24, the raw fuel gas supply valves 42 and 43, the raw fuel gas pump 45, the three-way valve 53, the air blower 55, the reforming water pump 68, the circulation pump 73, the pressure sensor 47, the flow sensors 48 and 56, It functions as a direct current power supply that supplies direct current power to auxiliary devices such as the display panel 90, the temperature sensor 91, the current sensor 92, the voltage sensor 93, and the combustible gas sensor 95.

  The control device 80 is configured as a microprocessor centering on the CPU 81, and in addition to the CPU 81, a ROM 82 for storing processing programs, a RAM 83 for temporarily storing data, and a flash memory as a rewritable non-volatile memory 84, a timer 85 for clocking, and an input / output port (not shown). Various detection signals from the pressure sensor 47, the flow sensors 48, 56, the temperature sensor 91, the current sensor 92, the voltage sensor 93, the combustible gas sensor 95, etc. are input to the control device 80 through the input port. In addition, from the control device 80, a drive signal to the fan motor of the ventilation fan 24, a drive signal to the solenoids of the raw fuel gas supply valves 42, 43, a drive signal to the pump motor of the raw fuel gas pump 45 Drive signal to the solenoid, drive signal to the blower motor of the air blower 55, drive signal to the pump motor of the reforming water pump 68, drive signal to the pump motor of the circulation pump 73, inverter and DC / DC converter of the power conditioner 78 Control signals, drive signals to the ignition heater 35, display signals to the display panel 90 for displaying various information, and the like are output via the output port.

  In the fuel cell system 10 configured in this way, when the system startup is instructed, the startup process is performed. In the start-up process, for example, after the corresponding accessories are sequentially controlled and warm-up process of the air blower 55 or purge process of the combustion unit 34 with air from the air blower 55 is performed, the ignition process of the off gas is performed in the combustion unit 34. Is performed to start combustion, and when a predetermined temperature is reached, steam reforming is performed. Note that, depending on the configuration of the fuel cell system 10, the state of auxiliary equipment, and the like, any of these processes may be omitted.

  Further, in the fuel cell system 10, the power generation process is performed following the start-up process. The power generation process is performed by inputting a load command accompanied by the load fluctuation of the load 4 and controlling the operation of the auxiliary machinery so that the required power corresponding to the load command is output within the range of the rated output. Further, depending on the input load command, operation control is performed so as to perform steady operation at the rated output. In operation control, basically, the target gas flow rate is set by feedback control based on the deviation between the required power and the detected power, and feedback control based on the deviation between the target gas flow rate and the gas flow rate detected by the flow rate sensor 48 The pump motor of the raw fuel gas pump 45 is controlled. The detected power can be calculated, for example, as the product of the output current I detected by the current sensor 92 and the output voltage V detected by the voltage sensor 93. Further, the target air flow rate is set so that a predetermined air fuel ratio is obtained with respect to the target gas flow rate, and the blower motor of the air blower 55 is driven by feedback control based on the deviation between the target air flow rate and the air flow rate Q detected by the flow rate sensor 56 It is controlled. Here, if the internal resistance increases due to the progress of deterioration of the fuel cell stack 36 and the generated voltage V of the fuel cell stack 36 decreases, it is necessary to increase the current flowing through the fuel cell stack 36 to maintain the required power output. Therefore, the calorific value of the fuel cell stack 36 is increased. Thus, the amount of air supplied from the air blower 55 is increased to perform air cooling of the fuel cell stack 36 so that the fuel cell stack 36 does not exceed the predetermined upper limit temperature. When this air cooling is performed, a value obtained by adding an air flow rate for air cooling to the basic air flow rate Q0 for setting a predetermined air-fuel ratio etc. to the target gas flow rate is set as the target air flow rate described above. It will be.

  In addition, the control device 80 performs stop processing when instructed to stop the system. In the stop process, the blower motor of the air blower 55 is supplied to supply air at a larger flow rate per unit time (for example, about several times such as two times) in order to lower the temperature of the fuel cell stack 36 quickly. Driving control is performed to air-cool the fuel cell stack 36. Then, when the temperature of the fuel cell stack 36 falls to a temperature below the temperature at which the electrochemical reaction is promoted, for example, to a temperature of about 300 to 400 ° C., the supply of the raw fuel gas is stopped. Furthermore, when the temperature of the fuel cell stack 36 is lowered to, for example, about 100 to 200 ° C., the supply of air is stopped. Note that such stop processing is performed periodically (at least once every month, for example) when inspecting the gas flow rate in the gas supply source 1, for example.

  Next, a process when the air supply device 50 switches the flow path for introducing air to either the chemical filter flow path 51a or the bypass flow path 51b will be described. FIG. 3 is a flowchart showing an example of the start / stop switching processing routine. This routine is executed at predetermined time intervals by the CPU 81 of the control device 80 during start-up processing and stop processing.

  When this routine is executed, the CPU 81 of the control device 80 first acquires the fuel cell temperature T which is the temperature of the fuel cell stack 36 detected by the temperature sensor 91 (S100), and the fuel cell temperature T is a predetermined temperature It is determined whether it is Tref or less (S110). Here, the predetermined temperature Tref is set to, for example, about 300 to 400 ° C. as a temperature below the temperature at which the electrochemical reaction of the fuel cell stack 36 is promoted. The predetermined temperature Tref may have a hysteresis so that the flow path for introducing air is not switched frequently. Further, although the fuel cell temperature T directly detected by the temperature sensor 91 is acquired in S100, the invention is not limited thereto, and the fuel indirectly detected by a temperature sensor (not shown) that detects the temperature in the module case 31 or the like. The battery temperature T may be acquired.

  When the CPU 81 determines that the fuel cell temperature T is lower than or equal to the predetermined temperature Tref in S110, the three-way valve 53 switches the connection destination (the flow path for introducing air) of the supply flow path 51c to the chemical filter flow path 51a. If it is (S120), drive control of the three-way valve 53 is performed to switch to the bypass flow passage 51b (S130), and this routine is ended. Further, if the CPU 81 has not switched the connection destination of the supply flow path 51c to the chemical filter flow path 51a (S120), the CPU 81 has already switched to the bypass flow path 51b, so this routine ends. Do. On the other hand, if the CPU 81 determines in S110 that the fuel cell temperature T does not fall below the predetermined temperature Tref but exceeds the predetermined temperature Tref, the three-way valve 53 switches the connection destination of the supply flow passage 51c to the bypass flow passage 51b. For example (S140), drive control of the three-way valve 53 is performed to switch to the chemical filter flow path 51a (S150), and this routine is ended. In addition, if the three-way valve 53 has not switched the connection destination of the supply flow passage 51c to the bypass flow passage 51b (S140), the CPU 81 has already switched to the chemical filter flow passage 51a, so this routine ends Do.

  As described above, during the start-up process or the stop process of the fuel cell system 10, when the fuel cell temperature T is higher than the predetermined temperature Tref and the electrochemical reaction of the fuel cell stack 36 is promoted, the air passing through the chemical filter 52 is used. The air is supplied without passing through the chemical filter 52 when the fuel cell temperature T is lower than the predetermined temperature Tref. Therefore, for example, when the warm-up process of the air blower 55 is performed in the start-up process, when the purge process of the combustion unit 34 is performed, the supply of the raw fuel gas is stopped in the stop process, etc. In the case where the progress of the deterioration of the fuel cell stack 36 is small, it is possible to prevent the chemical filter 52 from wastefully adsorbing the impurities, as air is not allowed to pass through the chemical filter 52. Since adsorption of impurities by the chemical filter 52 has a limit (upper limit), the life of the chemical filter 52 can be extended by preventing waste adsorption of the impurities. Further, when deterioration of the fuel cell stack 36 is promoted by impurities in the air, such as when the fuel cell temperature T becomes high in the start-up process, or when the fuel cell stack 36 is not sufficiently cooled in the stop process. In order to prevent the fuel cell stack 36 from being deteriorated, the chemical filter 52 can appropriately remove impurities in the air by passing the air through the chemical filter 52.

  FIG. 4 is a flowchart showing an example of the power generation switching process routine. This routine is executed by the CPU 81 of the control device 80 at predetermined time intervals during the power generation process.

  When this routine is executed, the CPU 81 of the control device 80 first obtains the air flow rate Q detected by the flow rate sensor 56 (S200), and the air flow rate Q is a predetermined flow rate obtained by multiplying the basic air flow rate Q0 by the coefficient α. It is determined whether or not α · Q 0 or less (S 210). As described above, the basic air flow rate Q0 is a flow rate for setting a predetermined air-fuel ratio to the target gas flow rate, and the target air flow rate is a flow rate for air-cooling the high temperature fuel cell stack 36 to the basic air flow rate Q0. The added flow rate is set. Therefore, when the fuel cell stack 36 is deteriorated, the air flow rate Q detected by the flow rate sensor 56 is larger than the basic air flow rate Q0. The coefficient α is set to, for example, a value 1.1 or a value 1.2 or the like as a value for determining such an increase in the flow rate of air. Note that the predetermined flow rate α · Q 0 (coefficient α) may have hysteresis or the like so that the flow path for introducing the air is not switched frequently. Further, although the air flow rate Q as the actual measurement value detected by the flow rate sensor 56 is acquired in S200, the invention is not limited thereto, and the air flow rate as a target value such as the above-described target air flow rate may be acquired.

  If the CPU 81 determines that the air flow rate Q is less than or equal to the predetermined flow rate α · Q0 in S210, the three-way valve 53 switches the connection destination of the supply flow path 51c to the chemical filter flow path 51a (S220), The drive control of the three-way valve 53 is performed to switch to the bypass flow passage 51b (S230), and this routine is ended. If the CPU 81 has not switched the connection destination of the supply flow path 51c to the chemical filter flow path 51a (S220), the CPU 81 has already switched to the bypass flow path 51b, so this routine ends. Do. On the other hand, when the CPU 81 determines that the air flow rate Q exceeds the predetermined flow rate α · Q0 instead of the predetermined flow rate α · Q0 in S210, the three-way valve 53 switches the connection destination of the supply flow path 51c to the bypass flow path 51b. If it is in the state (S240), drive control of the three-way valve 53 is performed to switch to the chemical filter channel 51a (S250), and this routine is ended. Further, if the CPU 81 has not switched the connection destination of the supply flow path 51c to the bypass flow path 51b (S240), the CPU 81 has already switched to the chemical filter flow path 51a, so this routine ends. Do.

  As described above, during the power generation process, when the air flow rate Q is larger than the predetermined flow rate α · Q 0 and the air supply amount to the fuel cell stack 36 is increasing, the air passing through the chemical filter 52 is supplied. When the flow rate is less than the predetermined flow rate α · Q 0, air is supplied without passing through the chemical filter 52. Therefore, when the absolute amount of impurities that can reach the fuel cell stack 36 increases and the deterioration of the fuel cell stack 36 tends to be accelerated because the air supply amount is increased, the air using the chemical filter 52 is used. Since the impurities in the fuel cell can be appropriately removed, it is possible to suppress the further progress of the deterioration of the fuel cell stack 36. Further, when the air supply amount is not increased, the life of the chemical filter 52 can be extended without using the chemical filter 52.

  Thus, the fuel cell system 10 switches the air introduction path based on the routine of FIG. 3 during the start-up process, switches the air introduction path based on the routine of FIG. 4 during the power generation process, and FIG. The air introduction path is switched based on the following routine. Therefore, for example, if the fuel cell temperature T exceeds the predetermined temperature Tref in the start-up process, the bypass flow path 51b is switched to the chemical filter flow path 51a, the power generation process is started, and the air flow rate Q is less than the predetermined flow rate α · Q0. For example, the bypass flow path 51b is used, and if the air flow rate Q exceeds the predetermined flow rate α · Q0, the chemical filter flow path 51a is used. In addition, when the power generation process is shifted to the stop process, regardless of the air introduction path during the power generation process, while the fuel cell temperature T exceeds the predetermined temperature Tref, the chemical filter flow path 51a is selected and the fuel cell temperature T is predetermined. When the temperature becomes equal to or lower than Tref, the chemical filter flow path 51a is changed to the bypass flow path 51b. By switching the air introduction path, the chemical filter 52 can be intermittently used to extend the life of the chemical filter 52. Particularly in the stop process, air is supplied at a large flow rate for air cooling until the fuel cell temperature T falls below the predetermined temperature Tref, so the possibility of deterioration of the fuel cell stack 36 becomes large. Since the air is supplied through the chemical filter 52, the fuel cell stack 36 can be cooled while appropriately suppressing the deterioration of the fuel cell stack 36.

  In the fuel cell system 10 described above, the three-way valve 53 switches the chemical filter flow path 51 a provided with the chemical filter 52 and the bypass flow path 51 b bypassing the chemical filter 52 to supply air to the fuel cell stack 36. . For this reason, since it is not necessary to always pass air through the chemical filter 52, accumulation of impurities in the chemical filter 52 can be suppressed. Therefore, it is possible to prolong the use period (life extension) of the chemical filter 52 while preventing the size increase and cost increase of the chemical filter 52.

  Further, in the fuel cell system 10, when the fuel cell temperature T of the fuel cell stack 36 is lower than or equal to the predetermined temperature Tref during the start-up process or the stop process, the connection destination of the supply flow path 51c is switched to the bypass flow path 51b. When the battery temperature T exceeds the predetermined temperature Tref, the connection destination of the supply flow path 51c is switched to the chemical filter flow path 51a. Therefore, by not using the chemical filter 52 when the fuel cell temperature T is low and the reaction of impurities hardly occurs, it is possible to suppress the influence of the impurities due to the air not passing through the chemical filter 52. In particular, during the stop process, the fuel cell stack 36 can be cooled while suppressing deterioration with air from which impurities are removed through the chemical filter 52 until the fuel cell temperature T reaches the predetermined temperature Tref. After the temperature falls below the predetermined temperature Tref, the fuel cell stack 36 can be cooled by the air passing through the bypass flow passage 51b in order to suppress the accumulation of impurities in the chemical filter 52.

  Further, in the fuel cell system 10, when the air flow rate Q is less than the predetermined flow rate α · Q0 during the power generation process, the connection destination of the supply flow path 51c is switched to the bypass flow path 51b, and the air flow rate Q is the predetermined flow rate α · Q0. Switch the connection destination of the supply flow path 51c to the chemical filter flow path 51a. Therefore, by not using the chemical filter 52 when the air flow rate Q is small and the absolute amount of impurities is small, it is possible to suppress the influence of the impurities due to the air not passing through the chemical filter 52.

  Further, the fuel cell system 10 is provided with the physical filter 54 separately from the chemical filter 52, and even when the chemical filter 52 is not used, physical impurities can be removed through the air in the physical filter 54. The influence of impurities caused by impermeability of air to 52 can be further suppressed.

  In the embodiment described above, the connection destination of the supply flow passage 51c is switched to either the chemical filter flow passage 51a or the bypass flow passage 51b based on the fuel cell temperature T during the start-up process or the stop process. It is not limited to FIG. 5 is a flowchart showing the start / stop switching processing routine of the modification. In this start / stop switching process routine, the CPU 81 obtains the output voltage V of the fuel cell stack 36 instead of the fuel cell temperature T (S100a), and determines whether the obtained output voltage V is less than the predetermined voltage Vref Is determined (S110a). The predetermined voltage Vref can be set to a value capable of determining that the fuel cell stack 36 is generating power by the electrochemical reaction. Then, the CPU 81 switches the connection destination of the supply flow path 51c to the bypass flow path 51b when the output voltage V is lower than or equal to the predetermined voltage Vref (S120, S130), and the supply flow path when the output voltage V exceeds the predetermined voltage Vref. The connection destination of 51 c may be switched to the chemical filter channel 51 a (S 140, S 150). The present invention is not limited to switching the flow path based on the output voltage V, as long as it can determine that the fuel cell stack 36 is generating power, and based on the output of the power generation of the fuel cell stack 36 such as the output current I. What is necessary is to switch the introduction path of air.

  In the embodiment, during the power generation process, switching to either the chemical filter channel 51a or the bypass channel 51b is performed based on the air flow rate Q, but the present invention is not limited thereto. It is good also as things etc. For example, the power generation time generated by the fuel cell stack 36 may be measured by the timer 85, and switching may be performed each time the power generation time passes a predetermined time.

  In the embodiment and the modification, although switching to either the chemical filter passage 51a or the bypass passage 51b is made based on the fuel cell temperature T, the air flow rate Q, the output voltage V, the power generation time, etc. The invention is not limited to switching based on the value related to the operation of the power generation module 30, and it may be switchable to any one of the chemical filter channel 51a and the bypass channel 51b. For example, switching is performed based on elapsed time or time regardless of the state of power generation or presence of power generation, switching based on the switching instruction of the operator via the display panel 90, operation of the operation member such as a switching operation lever It is good also as what can be switched mechanically based on.

  In the embodiment, the physical filter 54 is provided in the supply flow passage 51c. However, the present invention is not limited to this. The physical filter 54 is provided in the bypass flow passage 51b like the air supply device 150 of the modification of FIG. It may be In this case, as described above, the chemical filter 52 may be added to the adsorption by the chemical reaction to enable the adsorption by the physical collection.

  In the embodiment, the chemical filter 52 and the physical filter 54 are separately disposed. However, the present invention is not limited to this, and as in the air supply device 250 of the modification of FIG. The filter 52 and the physical filter 54 may be accommodated, and an air inlet and an outlet for each filter may be provided in the housing 57.

  The correspondence between the main elements of the present embodiment and the main elements of the invention described in the section of “Means for Solving the Problems” will be described. In the present embodiment, the power generation module 30 corresponds to a "fuel cell", the fuel cell system 10 corresponds to a "fuel cell system", the chemical filter 52 corresponds to a "chemical filter", and the chemical filter channel 51a is " The bypass channel 51b corresponds to the "bypass channel", the air supply pipe 51 corresponds to the "air channel", the air blower 55 corresponds to the "blower", and the three-way valve 53 Corresponds to the "switching valve". Moreover, the control apparatus 80 which performs S110-S150 of FIG. 3, S210-S250 of FIG. 4, and S110a-S150 of FIG. 5 corresponds to a "control apparatus." Further, the control device 80 for acquiring the fuel cell temperature T detected by the temperature sensor 91 in S100 of FIG. 3 corresponds to the “temperature acquisition means”. Further, the control device 80 for acquiring the air flow rate Q detected by the flow rate sensor 56 in S200 of FIG. 4 corresponds to the “flow rate acquisition means”. Further, the control device 80 for acquiring the output voltage V detected by the voltage sensor 93 in S100a of FIG. 5 corresponds to the “output acquisition means”. Also, the physical filter 54 corresponds to a "physical filter".

  The correspondence between the main elements of the present embodiment and the main elements of the invention described in the section of the means for solving the problems is the invention described in the section of the means for the present embodiment for solving the problems. The present invention is not limited to the elements of the invention described in the section of “Means for Solving the Problems”, as it is an example for specifically explaining the mode for carrying out the invention. That is, the interpretation of the invention described in the section of the means for solving the problem should be made based on the description of the section, and the present embodiment is the invention described in the section of the means for solving the problem It is only a specific example of

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited at all by such embodiment, It can be implemented with various forms in the range which does not deviate from the summary of this invention. Of course.

  The present invention is applicable to, for example, the manufacturing industry of fuel cell systems.

  Reference Signs List 1 gas supply source, 2 commercial power source, 3 power line, 4 load, 10 fuel cell system, 20 power generation unit, 22 housings, 22a inlet, 22b outlet, 24 ventilation fan, 30 power generation module, 31 module case, 32 Vaporizer, 33 reformer, 34 combustion unit, 35 ignition heater, 36 fuel cell stack, 37 combustion catalyst, 40 raw fuel gas supply device, 41 raw fuel gas supply pipe, 42, 43 raw fuel gas supply valve, 44 orifice , 45 raw fuel gas pump, 46 desulfurizer, 47 pressure sensor, 48 flow sensor, 50, 150, 250 air supply device, 51 air supply pipe, 51a chemical filter flow path, 51b bypass flow path, 51c supply flow path, 52 chemistry Filter, 53 three-way valve, 54 physical filter, 55 air blower, 56 flow sensor, 7 case, 65 reforming water supply device, 66 reforming water supply pipe, 67 reforming water tank, 68 reforming water pump, 70 exhaust heat recovery device, 71 circulation piping, 72 heat exchanger, 73 circulation pump, 76 Condensed water supply pipe, 77 exhaust gas discharge pipe, 78 power conditioner, 79 power supply board, 80 controller, 81 CPU, 82 ROM, 83 RAM, 84 flash memory, 85 timer, 90 display panel, 91 temperature sensor, 92 current Sensor, 93 voltage sensor, 95 combustible gas sensor, 100 hot water supply unit, 101 hot water storage tank.

Claims (7)

What is claimed is: 1. A fuel cell system comprising a fuel cell generating electricity based on fuel gas and air, comprising:
Chemical filters that can remove impurities in the air by chemical reaction,
A chemical filter flow path provided with the chemical filter, and a bypass flow path bypassing the chemical filter, and air is directed to the fuel cell through either the chemical filter flow path or the bypass flow path With the air flow path,
A blower provided in the air flow path to supply air to the fuel cell by driving;
A switching valve which is provided in the air flow path and switches a flow path through which air toward the fuel cell passes to either the chemical filter flow path or the bypass flow path;
A fuel cell system comprising: The fuel cell system according to claim 1, wherein
A fuel cell system comprising: a control device that controls the switching valve such that air supplied to the fuel cell intermittently passes through the chemical filter flow path. The fuel cell system according to claim 2, wherein
A temperature acquisition unit configured to acquire the temperature of the fuel cell;
The control device controls the switching valve such that air passes through the bypass flow path when the temperature of the fuel cell is equal to or lower than a predetermined temperature, and the air when the temperature of the fuel cell exceeds the predetermined temperature Controlling the switching valve so that the fuel passes through the chemical filter flow path. The fuel cell system according to claim 2, wherein
A flow rate acquiring unit configured to acquire a flow rate of air passing through the air flow path;
The control device controls the switching valve so that the air passes through the bypass flow path when the flow rate of air in the air flow path is equal to or less than a predetermined flow rate, and the flow rate of air in the air flow path is the predetermined flow rate And controlling the switching valve such that air passes through the chemical filter flow path. The fuel cell system according to claim 2, wherein
An output acquiring unit that acquires a voltage or a current as an output of power generation of the fuel cell;
The control device controls the switching valve such that air passes through the bypass flow path when the voltage or the current is less than a predetermined value, and air when the voltage or the current exceeds the predetermined value. Controlling the switching valve so that the fuel passes through the chemical filter flow path. The fuel cell system according to claim 2, wherein
The fuel cell is a solid oxide fuel cell,
A temperature acquisition unit configured to acquire the temperature of the fuel cell;
The control device controls the switching valve to cool the fuel cell by air passing through the chemical filter flow path until the temperature of the fuel cell falls below a predetermined temperature when the operation of the fuel cell is stopped. And controlling the switching valve so as to cool the fuel cell by air passing through the bypass flow path after the temperature of the fuel cell has become equal to or lower than the predetermined temperature. The fuel cell system according to any one of claims 1 to 6, wherein
It has a physical filter that physically removes impurities in the air without chemical reaction,
The physical filter is provided in the bypass flow channel, or is provided in the air flow channel so that air passing through the bypass flow channel passes through.

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