JP2015185536A - fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of suppressing influence on equipment when suppressing a pressure rise around a desulfurizer.SOLUTION: A fuel cell system 1 comprises: a desulfurizer 11; a reformer 51; a fuel cell 53; a raw material line 18 to be desulfurized; a first cutoff valve 21 provided in the raw material line 18 to be desulfurized; a desulfurized raw material line 19; a second cutoff valve 22 provided in the desulfurized raw material line 19; a desulfurizer inner pressure detector 23 which detects an inner pressure of the desulfurizer 11; an air supply unit 31 for reforming which supplies an air AR for reforming to the reformer 51; and a control unit 60. When the pressure detected by the desulfurizer inner pressure detector 23 becomes more than or equal to a first prescribed value, the control unit 60 supplies the air AR for reforming to the reformer 51, opens the second cutoff valve 22, and reduces the pressure of the desulfurizer inner pressure detector 23 to a second prescribed value (pressure reduction processing). At this time, a raw material D is diluted with the air AR for reforming and discharged to the outside.

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system that suppresses the influence on equipment when performing a process of suppressing a pressure increase around a desulfurizer.

  When installing a fuel cell that generates electricity by introducing a hydrogen-containing gas and an oxygen-containing gas, in view of the lack of infrastructure to obtain the hydrogen-containing gas, the hydrocarbon-based raw material is reformed to produce a hydrogen-containing gas. In many cases, a reformer (fuel processor) is attached. When the hydrogen-containing gas supplied to the fuel cell is produced by reforming a hydrocarbon-based raw material, it is generally reformed after desulfurizing the hydrocarbon-based raw material in a desulfurizer.

  The pressure compensation processing for the space including the fuel processor, which is necessary due to the difference in pressure change due to the difference in temperature change after the shutdown of the desulfurizer and fuel processor with different temperatures during operation, is performed as follows. Fuel processing devices are known. The fuel processing apparatus includes a first valve provided in a raw material gas flow path upstream of a desulfurizer, a second valve provided in a raw material gas flow path between the desulfurizer and the fuel processor, a fuel A third valve provided downstream of the processor, and in a state in which the pressure in the space including the desulfurizer is pressurized to a pressure equal to or higher than the first pressure threshold, the space is supplemented in the space including the fuel processor. When processing is performed, the second valve is opened while the first valve and the third valve are closed (see, for example, Patent Document 1).

JP 2009-217952 A (paragraph 0030, FIG. 1, etc.)

  However, in the fuel processor described in Patent Document 1, when the raw material gas sealed between the first valve and the third valve is discharged, the fuel processor is installed on the downstream side of the fuel processor. There is a risk of malfunctioning of devices such as gas detectors constituting the fuel cell system.

  In view of the above-described problems, an object of the present invention is to provide a fuel cell system that suppresses the influence on devices when performing a process of suppressing a pressure increase around a desulfurizer.

  In order to achieve the above object, the fuel cell system according to the first aspect of the present invention provides a desulfurized raw material Df by desulfurizing a raw material Dr to be desulfurized, which is a hydrocarbon-based raw material, for example, as shown in FIG. A desulfurizer 11 to be generated; a reforming section 51 for reforming the desulfurized raw material Df to generate a fuel gas E containing hydrogen; and a fuel cell 53 for generating power by introducing the fuel gas E and power generation air AG A desulfurized raw material line 18 for introducing the desulfurized raw material Dr to the desulfurizer 11; a first shut-off valve 21 provided in the desulfurized raw material line 18; and the desulfurized raw material Df from the desulfurizer 11 to the reforming unit 51. A desulfurized raw material line 19 to be guided; a second shut-off valve 22 provided in the desulfurized raw material line 19; a desulfurizer internal pressure detector 23 for directly or indirectly detecting the pressure inside the desulfurizer 11; To the desulfurized raw material line 19 downstream of the shutoff valve 22 of The reforming air supply unit 31 for supplying the reforming air AR to the mass part 51; the desulfurizer internal pressure detector 23 detects the first shutoff valve 21 and the second shutoff valve 22 in a closed state. When the pressure becomes equal to or higher than the first predetermined value, the reforming air AR is supplied to the reforming unit 51 and the second shutoff valve 22 is opened to open the desulfurizer internal pressure detector 23. The control unit 60 that operates the reforming air supply unit 31 and the second shut-off valve 22 so as to perform a pressure reduction process that lowers the pressure detected by the pressure to a second predetermined value that is smaller than the first predetermined value. With.

  With this configuration, the second shut-off valve is opened while the reforming air is supplied, so the hydrocarbon-based raw material that has flowed down through the second shut-off valve is diluted with the reforming air. As a result, the influence on the equipment can be suppressed.

  Further, the fuel cell system according to the second aspect of the present invention supplies power generation air AG to the fuel cell 53 in the fuel cell system 1 according to the first aspect of the present invention as shown in FIG. The control unit 60 includes the reforming air toward the reforming unit 51 when the pressure detected by the desulfurizer internal pressure detector 23 is equal to or higher than the first predetermined value. In addition to supplying AR, the power generation air supply unit 41 is operated so as to supply power generation air AG toward the fuel cell 53.

  If comprised in this way, a raw material will be diluted also with power generation air in addition to reforming air, and the influence on equipment can be suppressed more.

  Further, for example, as shown in FIG. 1, the fuel cell system according to the third aspect of the present invention is externally provided by the decompression process in the fuel cell system 1 according to the first aspect or the second aspect of the present invention. Discharge flow rate suppression means 22 and 60 for suppressing the discharge flow rate of the raw material D to the outside are provided so that the discharged raw material D is discharged outside at a concentration below the lower limit of combustion.

  If comprised in this way, a raw material can be discharged | emitted gently outside.

  Moreover, when the fuel cell system according to the fourth aspect of the present invention is shown, for example, with reference to FIG. 1, in the fuel cell system 1 according to the third aspect of the present invention, the discharge flow rate suppression means is a control unit. 60 is configured by repeatedly opening and closing the second shut-off valve 22.

  If comprised in this way, a raw material can be discharged | emitted gently outside by control, without providing a special apparatus.

  In addition, when the fuel cell system according to the fifth aspect of the present invention is shown, for example, with reference to FIG. 1, in the fuel cell system 1 according to the fourth aspect of the present invention, the control unit 60 has a desulfurizer internal pressure. When the pressure detected by the detector 23 is equal to or lower than a third predetermined value between the first predetermined value and the second predetermined value, the second shutoff valve 22 is kept open. It is configured.

  If comprised in this way, the increase in the frequency | count of opening and closing of a 2nd cutoff valve can be suppressed, and the lifetime of a 2nd cutoff valve can be extended.

  Moreover, when the fuel cell system according to the sixth aspect of the present invention is shown, for example, with reference to FIG. 1, in the fuel cell system 1 according to the fourth aspect or the fifth aspect of the present invention, the control unit 60. Is configured to maintain the second shut-off valve 22 in an open state when the number of opening / closing operations of the second shut-off valve 22 exceeds a predetermined number.

  If comprised in this way, when the abnormality of discharge | emission of a raw material arises, it can avoid that the frequency | count of opening and closing of a 2nd cutoff valve increases unnecessarily, and the lifetime of a 2nd cutoff valve can be extended.

  In addition, when the fuel cell system according to the seventh aspect of the present invention is shown, for example, with reference to FIG. 1, in the fuel cell system 1 according to the third aspect of the present invention, the discharge flow rate suppression means includes a control unit 60 is configured by adjusting the opening of the second shut-off valve 22.

  If comprised in this way, a raw material can be discharged | emitted gently outside by control, without providing a special apparatus.

  Further, the fuel cell system according to the eighth aspect of the present invention is, for example, referring to FIG. 1, and the fuel cell system according to any one of the first to seventh aspects of the present invention. 1, when the pressure detected by the desulfurizer internal pressure detector 23 exceeds the second predetermined value when the first predetermined time has elapsed since the start of the pressure reduction process. It is configured to estimate that there is an abnormality.

  If comprised in this way, it will become possible to avoid continuing a driving | operation with the possibility that abnormality may have arisen.

  Moreover, the fuel cell system according to the ninth aspect of the present invention, for example, referring to FIG. 1, shows the fuel cell system according to any one of the first to eighth aspects of the present invention. 1, when the controller 60 performs the pressure reduction process, when the decrease in pressure detected by the desulfurizer internal pressure detector 23 is less than the first predetermined difference within the second predetermined time, or The desulfurizer internal pressure detector 23 is configured to estimate that there is an abnormality when a third predetermined time elapses before the pressure detected by the second predetermined difference decreases.

  If comprised in this way, it will become possible to avoid continuing a driving | operation with the possibility that abnormality may have arisen.

  Moreover, as a method for eliminating the overpressure of the desulfurizer according to the tenth aspect of the present invention, for example, referring to FIGS. 1 and 2, a raw material D present in the desulfurizer 11 for desulfurizing a hydrocarbon-based raw material A raw material sealing step (S1) for sealing the raw material; a desulfurizer internal pressure detection step (S2) for directly or indirectly detecting the pressure inside the desulfurizer 11 in which the raw material D is sealed; and a desulfurizer internal pressure detection step (S2) Is supplied to the reforming unit 51 that can communicate with the desulfurizer 11 and the raw material in the desulfurizer 11 is supplied to the desulfurizer 11. A pressure reduction treatment step (S5) for reducing the pressure inside the desulfurizer 11 to a second predetermined value smaller than the first predetermined value by discharging toward the reforming unit 51 may be provided. Good.

  If comprised in this way, the raw material discharged | emitted from a desulfurizer will be diluted with reforming air, and the influence on equipment can be suppressed.

  According to the present invention, the raw material is diluted with the reforming air, and the influence on the equipment can be suppressed.

1 is a schematic system diagram of a fuel cell system according to an embodiment of the present invention. It is a flowchart of the overpressure elimination control of the desulfurizer in the fuel cell system which concerns on embodiment of this invention.

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

  First, a fuel cell system 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic system diagram of the fuel cell system 1. The fuel cell system 1 includes a desulfurizer 11 that desulfurizes the raw material D, a reformer 51 as a reforming unit that reforms the raw material D desulfurized by the desulfurizer 11 into a fuel gas E rich in hydrogen, and a fuel cell 53. And a control unit 60 as main components.

  The raw material D can be made into a gas rich in hydrogen (hydrogen-rich gas) that can be used for power generation in the fuel cell 53 by reforming, and a hydrocarbon-based fuel is used. Specific examples include hydrocarbons, alcohols, ethers, biofuels, and these hydrocarbon fuels are derived from fossil fuels such as petroleum and coal, those derived from synthetic fuels such as synthesis gas, Those derived from biomass can be used as appropriate. Examples of hydrocarbons include methane, ethane, propane, butane, natural gas, LPG, city gas, town gas, gasoline, naphtha, kerosene, and light oil. Examples of alcohols include methanol and ethanol. Examples of ethers include dimethyl ether. Examples of biofuels include biogas, bioethanol, biodiesel, and biojet. In the following description, the raw material D before being desulfurized by the desulfurizer 11 is referred to as a pre-desulfurized raw material Dr, and the raw material D after being desulfurized by the desulfurizer 11 is referred to as a desulfurized raw material Df. This is collectively referred to as raw material D. The raw material Dr before desulfurization corresponds to the raw material to be desulfurized.

  The desulfurizer 11 has therein a desulfurization catalyst 11c that adsorbs a sulfur content contained in the raw material Dr before desulfurization. As the desulfurization catalyst 11c, a zeolite catalyst or a metal catalyst is used. The desulfurizer 11 includes a pre-desulfurization raw material pipe 18 that leads the raw material Dr before desulfurization to the desulfurizer 11 and a desulfurized raw material pipe as a desulfurized raw material line that leads the desulfurized raw material Df to the reformer 51. 19 is connected. A "... line" is a fluid flow path, typically a tube that exclusively guides the fluid, but is a space formed between objects used for other purposes. There may be. The raw material pipe 18 before desulfurization is provided with a first shut-off valve 21 as a first shut-off valve capable of shutting off the flow path. An upstream shut-off valve 29 is disposed on the pre-desulfurization raw material pipe 18 upstream of the first shut-off valve 21. The desulfurized raw material pipe 19 is provided with a second shutoff valve 22 as a second shutoff valve capable of shutting off the flow path. In the present embodiment, electromagnetic valves are used for the first cutoff valve 21 and the second cutoff valve 22. A raw material blower 13 that pumps the desulfurized raw material Df toward the reformer 51 is disposed in the desulfurized raw material pipe 19 downstream of the second shut-off valve 22. A pre-desulfurization raw material pipe 18 between the desulfurizer 11 and the first shut-off valve 21 is provided with a pressure gauge 23 as a desulfurizer internal pressure detector. The pressure gauge 23 only needs to be able to detect the pressure inside the desulfurizer 11, and may be provided in the desulfurized raw material pipe 19 or the desulfurizer 11 upstream of the second shutoff valve 22.

  The reformer 51 includes a reforming catalyst 51c that promotes reforming of the desulfurized raw material Df. In the present embodiment, a self-heat reforming catalyst is accommodated in the reformer 51 as the reforming catalyst 51c. Connected to the reformer 51 are a desulfurized raw material pipe 19, a reforming air pipe 32 as a reforming air line for introducing the reforming air AR, and a reforming water introduction pipe (not shown). ing. The reforming air pipe 32 is provided with a reforming air blower 33 that pumps the reforming air AR toward the reformer 51. A reforming air supply unit 31 is configured including the reforming air pipe 32 and the reforming air blower 33. The reformer 51 introduces the desulfurized raw material Df, the reforming air AR, and the reforming water, burns a part of the hydrocarbons in the desulfurized raw material Df with the reforming air AR, and generates heat. Thus, the hydrocarbon in the desulfurized raw material Df and the reformed water (steam) are reformed under the reforming catalyst 51c to generate the fuel gas E. Also connected to the reformer 51 is a fuel gas pipe 52 as a fuel gas line for leading the generated fuel gas E.

  The fuel cell 53 is connected to the reformer 51 through a fuel gas pipe 52. The fuel cell 53 is also connected with a power generation air pipe 42 as a power generation air line for introducing the power generation air AG. The power generation air pipe 42 is provided with a power generation air blower 43 that pumps the power generation air AG toward the fuel cell 53. A power generation air supply unit 41 is configured including the power generation air pipe 42 and the power generation air blower 43. The fuel cell 53 is configured to introduce the fuel gas E and the power generation air AG and generate DC power by an electrochemical reaction between hydrogen or the like in the fuel gas E and oxygen in the power generation air AG. In some cases, it is generally called a cell stack. As the fuel cell 53, in this embodiment, a solid oxide fuel cell (SOFC) of a cylindrical type (including a flat plate cylindrical type) is used, but a SOFC such as a solid polymer fuel cell (PEFC) is used. Other fuel cells may be used. The fuel gas E and power generation air AG supplied to the fuel cell 53 for power generation in the fuel cell 53 are not all used for power generation, but the amount corresponding to the power generation current of the fuel cell 53 is used. The portion not used for power generation is derived as off-gas F. In the present embodiment, a burner (not shown) for burning off gas F derived from the fuel cell 53 is provided on the downstream side of the fuel cell 53, and the off gas F is burned by the burner (not shown). The reformer 51 can be heated by the generated heat.

  The fuel cell system 1 includes a combustion unit 55 downstream of the fuel cell 53. The combustion unit 55 introduces the off-gas F after being discharged from the fuel cell 53 and burned by a burner (not shown), and burns unburned combustible components contained in the off-gas F after the primary combustion. It is configured. The combustion unit 55 is mainly for burning unburned components in the off-gas F after the primary combustion, but is disposed adjacent to the reformer 51 and serves as a reforming catalyst 51c in the reformer 51. You may be comprised so that heat can be given. The combustion unit 55 includes a combustion catalyst (not shown) that burns combustible components in the off-gas F after the primary combustion, and a heater 55h that raises the temperature of the combustion catalyst to an activation temperature. The combustion catalyst is composed of a substance that promotes oxidation of the combustible component in the off-gas F after the primary combustion. For example, a noble metal catalyst such as platinum or palladium or a base metal catalyst such as manganese or iron is used. be able to. The heater 55h is configured to have a calorific value that can quickly raise the combustion catalyst (not shown) to the activation temperature when the fuel cell system 1 is started. The combustion unit 55 is configured to discharge the exhaust gas G generated by the combustion of the off gas F after the primary combustion. An exhaust gas pipe 59 as an exhaust gas line through which the exhaust gas G flows is connected to the combustion unit 55.

  The control unit 60 is a device that controls the operation of the fuel cell system 1. The control unit 60 is connected to the first shut-off valve 21 and the second shut-off valve 22 via signal cables, respectively, and is configured to be able to open and close the first shut-off valve 21 and the second shut-off valve 22. Yes. The control unit 60 is connected to the pressure gauge 23 via a signal cable, and is configured to receive a value detected by the pressure gauge 23 as a signal. The control unit 60 is connected to the raw material blower 13, the reforming air blower 33, and the power generation air blower 43 by signal cables, respectively, so that the start and stop of each of the blowers 13, 33, 43 can be controlled. It is configured. The control unit 60 is connected to the heater 55h via a signal cable, and is configured to be able to control on / off of the heater 55h.

  With continued reference to FIG. 1, the operation of the fuel cell system 1 will be described. When the control unit 60 receives a command to start the fuel cell system 1, the control unit 60 opens the first cutoff valve 21 and the second cutoff valve 22 and starts the raw material blower 13. The upstream shut-off valve 29 is normally open when the fuel cell system 1 is in operation. When the raw material blower 13 is activated, the raw material Dr before desulfurization is introduced into the desulfurizer 11 through the raw material pipe 18 before desulfurization. The raw material Dr before desulfurization becomes a desulfurized raw material Df that is desulfurized so that the sulfur content is adsorbed by the action of the desulfurization catalyst 11 c in the desulfurizer 11 and does not adversely affect the reformer 51 and the fuel cell 53. The desulfurizer 11 in which the raw material Dr before desulfurization is desulfurized is approximately 50 ° C. The desulfurized raw material Df is introduced into the reformer 51 through the desulfurized raw material pipe 19.

  When the desulfurized raw material Df is introduced into the reformer 51, the control unit 60 activates the reforming air blower 33. When the reforming air blower 33 is activated, the reforming air AR is introduced into the reformer 51 through the reforming air pipe 32. Further, reforming water is also introduced into the reformer 51 via a reforming water introduction pipe (not shown). In the reformer 51 into which the desulfurized raw material Df, the reforming air AR, and the reforming water are introduced, a self-thermal reforming reaction is performed and the fuel gas E is generated. The reformer 51 in which the autothermal reforming reaction is performed is approximately 600 ° C. When the temperature of the reformer 51 rises and the fuel gas E is stably generated, the reforming air blower 33 is stopped and the supply of the reforming air AR to the reformer 51 is stopped. The fuel gas E is generated by steam reforming with steam changed from the reformed water. The fuel gas E generated by the reformer 51 is supplied to the fuel cell 53 via the fuel gas pipe 52.

  When the fuel gas E is supplied to the fuel cell 53, the control unit 60 activates the power generation air blower 43. When the power generation air blower 43 is activated, the power generation air AG is introduced into the fuel cell 53 via the power generation air pipe 42. In the fuel cell 53 into which the fuel gas E and the power generation air AG are introduced, power generation is performed by an electrochemical reaction between hydrogen or the like in the fuel gas E and oxygen in the power generation air AG. The electric power generated in the fuel cell 53 is supplied to electric devices (each blower 13, 43, etc.) in the fuel cell system 1 and / or an electric power load (not shown) outside the fuel cell system 1. After the fuel gas E and the power generation air AG introduced into the fuel cell 53 are used for power generation, they are discharged as off-gas F, and are first burned by a burner (not shown) to give heat to the reformer 51. To the combustion section 55.

  In the combustion unit 55, since the combustion catalyst does not reach the activation temperature at the initial start of the fuel cell system 1, the control unit 60 operates the heater 55h to quickly raise the combustion catalyst to the activation temperature. When the combustion catalyst reaches the activation temperature, the controller 60 stops energizing the heater 55h. The off-gas F after the primary combustion introduced into the combustion unit 55 is combusted by the combustion catalyst. The combustion heat generated by the combustion of the off-gas F after the primary combustion in the combustion unit 55 may be used for the reforming reaction in the reformer 51. The exhaust gas G generated by the combustion of the off-gas F after the primary combustion in the combustion unit 55 flows through the exhaust gas pipe 59 and is discharged from the fuel cell system 1.

  In the fuel cell system 1 that operates as described above, when the power generation of the fuel cell 53 is stopped, the control unit 60 stops the material blower 13 and closes the first cutoff valve 21 and the second cutoff valve 22. . Thereby, the supply of the desulfurized raw material Df to the reformer 51 is stopped, and the supply of the fuel gas E to the fuel cell 53 is stopped. In addition, the control unit 60 stops the power generation air blower 43. Thereby, the supply of the power generation air AG to the fuel cell 53 is stopped. The portions of the desulfurizer 11 between the first shut-off valve 21 and the second shut-off valve 22 that are closed, and the pre-desulfurization raw material pipe 18 and the desulfurized raw material pipe 19 that are in communication with the desulfurizer 11 Since this is a sealed space, the internal pressure fluctuates in accordance with changes in the temperature of the surrounding environment. Typically, when the temperature of the desulfurizer 11 increases, the internal pressure increases, and when the temperature of the desulfurizer 11 decreases, the internal pressure decreases.

  In order to avoid an excessive increase in the pressure in the desulfurizer 11, the desulfurization is performed by opening the second shut-off valve 22 when the value detected by the pressure gauge 23 exceeds the first predetermined value. The pressure in the vessel 11 can be released. Here, the first predetermined value is an upper limit value of the pressure set from the viewpoint of protection of the desulfurizer 11, and may be, for example, 65 kPa (gauge pressure). By opening the second shut-off valve 22, the pressure in the desulfurizer 11 can be released. However, if the raw material D enclosed around the desulfurizer 11 flows out to the downstream side as it is, the fuel cell system 1 enters the fuel cell system 1. A malfunction of auxiliary equipment such as installed gas detectors may occur. In the fuel cell system 1, the following measures are taken to suppress the pressure increase in the desulfurizer 11 while avoiding malfunctions of auxiliary machinery.

  FIG. 2 is a flowchart of the overpressure elimination control of the desulfurizer 11 in the fuel cell system 1. In the following description, when referring to the configuration of the fuel cell system 1, FIG. 1 will be referred to as appropriate. During the stoppage of power generation, the fuel cell system 1 closes the first shutoff valve 21 and the second shutoff valve 22 to seal around the desulfurizer 11, and encloses the raw material D present in the desulfurizer 11. (Raw material encapsulation step: S1). And the control part 60 has received the value which the pressure gauge 23 detected suitably, and judges whether the value which the pressure gauge 23 detected is more than a 1st predetermined value (desulfurizer internal pressure detection process: S2). ). If the value detected by the pressure gauge 23 is not equal to or greater than the first predetermined value, the process returns to the desulfurizer internal pressure detection step (S2) again.

  On the other hand, in the desulfurizer internal pressure detection step (S2), when the value detected by the pressure gauge 23 is equal to or greater than the first predetermined value, the control unit 60 activates the reforming air blower 33 (S3). When the reforming air blower 33 is activated, the reforming air AR is supplied to the reformer 51. Further, the control unit 60 activates the power generation air blower 43 (S4). When the power generation air blower 43 is activated, the power generation air AG is supplied to the fuel cell 53. However, in the fuel cell system 1 in which power generation is stopped, the fuel gas E is not supplied to the fuel cell 53. For this reason, the power generation air AG supplied to the fuel cell 53 passes through the fuel cell 53 and flows through the exhaust gas pipe 59. Moreover, the control part 60 starts the repetition of opening and closing of the 2nd shut-off valve 22 (opening the 2nd shut-off valve 22 intermittently), The raw material D enclosed in the desulfurizer 11 is reformed by the reformer The pressure in the desulfurizer 11 is reduced (pressure reduction treatment step: S5). In the flow of FIG. 2, it is shown that the step of starting the reforming air blower 33 (S3) and the step of starting the power generating air blower 43 (S4) are performed in this order. Two processes (S3, S4) are started simultaneously. In addition, the step (S5) of starting to repeat the opening and closing of the second shut-off valve 22 is typically started with a slight delay from the start of the two steps (S3, S4), but the two steps (S3). , S4) may be started at the same time.

  When the second shut-off valve 22 is opened and the raw material D enclosed in the desulfurizer 11 is discharged, the reforming air AR and the power generation air AG are supplied, so that the raw material D is diluted and the fuel cell system 1 Thus, it is possible to avoid malfunction of auxiliary machinery that may occur when the raw material D is discharged as it is. Further, since the reforming air AR is supplied when the raw material D is discharged from the desulfurizer 11, the raw material D is prevented from being adsorbed on the reforming catalyst 51 c when passing through the reformer 51. It is possible to suppress a decrease in the capacity of the reforming catalyst 51c.

  Moreover, in this Embodiment, since opening and closing of the 2nd cutoff valve 22 is repeated, compared with the case where the 2nd cutoff valve 22 is maintained open, the flow volume of the raw material D discharged | emitted from the desulfurizer 11 becomes small. The time when the second shut-off valve 22 is opened and the time when the second shut-off valve 22 is open are determined by taking into account the characteristics of the second shut-off valve 22, the pressure inside the desulfurizer 11, and the like. The concentration is determined to be less than the lower limit. At this time, it is preferable that the raw material D discharged from the fuel cell system 1 has a concentration lower than the lower limit of combustion even when the power generation air AG is not supplied. For example, the second shutoff valve 22 can be controlled to be repeatedly opened for 0.1 seconds and then closed for 0.3 seconds (opening / closing ratio is 1: 3). As described above, in the present embodiment, the concentration of the raw material D discharged from the fuel cell system 1 by repeating the opening / closing operation of the second shutoff valve 22 controlled by the control unit 60 is set to a concentration lower than the lower combustion limit. The two shutoff valves 22 and the control unit 60 constitute discharge flow rate suppression means. In other words, the 2nd cutoff valve 22 and the control part 60 serve as the discharge flow rate suppression means.

  After performing the step (S5) of starting to repeat the opening and closing of the second shutoff valve 22, the control unit 60 determines whether or not the value detected by the pressure gauge 23 is equal to or less than a second predetermined value (desulfurizer internal pressure). Decrease confirmation step: S6). Here, the second predetermined value is a pressure that can prevent the desulfurizer 11 from becoming a negative pressure even if the temperature drops after the overpressure of the desulfurizer 11 is eliminated, for example, 40 kPa (gauge pressure). It can be. At this time, even if the value detected by the pressure gauge 23 falls below the second predetermined value, the value detected by the pressure gauge 23 has decreased from the first predetermined value in the process so far. , It does not deviate greatly from the second predetermined value. If the value detected by the pressure gauge 23 is not less than or equal to the second predetermined value, from the step (S5) of starting to repeat the opening and closing of the second shutoff valve 22 (starting to repeat the opening and closing of the second shutoff valve 22 From (S7), it is determined whether or not a first predetermined time has elapsed. Here, the first predetermined time is a time at which the pressure gauge 23 will detect the second predetermined value or less at the latest if there is no abnormality. When the first predetermined time has not elapsed, the control unit 60 determines whether or not the second predetermined time has elapsed since the reference time (S8). Here, the second predetermined time is an arbitrary time shorter than the first predetermined time, and it can be determined whether or not an abnormality has occurred. If any abnormality occurs, the component equipment is damaged. It is better to determine from the viewpoint that can be suppressed as much as possible. The second predetermined time can be, for example, 30 seconds. The reference time is typically when the measurement of the first predetermined time is started or when the second predetermined time of the previous time has elapsed.

  In the step of determining whether or not the second predetermined time has elapsed (S8), when the second predetermined time has elapsed, the control unit 60 starts measuring the second predetermined time. It is determined whether or not the decrease in the value detected by the pressure gauge 23 is less than the first predetermined difference (S9). Here, the first predetermined difference is a pressure difference that would have fallen within a second predetermined time if there is no abnormality. The first predetermined difference can be, for example, 1 kPa (gauge pressure). In the step (S9) of determining whether or not the decrease in the value detected by the pressure gauge 23 is less than the first predetermined difference, and when the above-mentioned first predetermined time has elapsed. When the first predetermined time has elapsed in the step of determining whether or not (S7), the control unit 60 estimates that there is some abnormality such as a failure of the second cutoff valve 22 (S10). In the present embodiment, when it is estimated that there is some abnormality (S10), the control unit 60 issues an error signal. At this time, the overpressure elimination control may be stopped together. In this way, by recognizing the possibility of occurrence of abnormality, it is possible to avoid continuing operation while there is a possibility that abnormality has occurred in the fuel cell system 1.

  When the second predetermined time has not elapsed in the step of determining whether or not the second predetermined time has elapsed (S8), and the decrease in the value detected by the pressure gauge 23 is the first predetermined When it is not less than the first predetermined difference in the step of determining whether or not the difference is less than (S9), the control unit 60 determines whether or not the value detected by the pressure gauge 23 is equal to or less than a third predetermined value ( S11). Here, even if the third predetermined value is the case where the second shutoff valve 22 is kept open, the flow rate of the raw material D discharged from the fuel cell system 1 is determined by whether the second shutoff valve 22 is opened or closed. The pressure is equal to or lower than that at the beginning of the step of starting the repetition (S5). In the step of determining whether or not the value detected by the pressure gauge 23 is equal to or smaller than the third predetermined value (S11), when the value is not equal to or smaller than the third predetermined value, the opening / closing of the second shutoff valve 22 is started repeatedly. From step (S5), it is determined whether or not the number of opening / closing operations of the second shut-off valve 22 exceeds a predetermined number (S12). Here, the predetermined number of times is an arbitrary number determined in consideration of the pressure drop in the desulfurizer 11 and the durability of the second shut-off valve 22, and is detected by the pressure gauge 23 in a normal state, for example. It is possible to set the number of times equal to or greater than the number of times the second shut-off valve 22 is opened / closed before the measured value decreases to the third predetermined value. In the step of determining whether or not the number of opening / closing operations of the second shut-off valve 22 exceeds a predetermined number (S12), if the predetermined number of times is not exceeded, the process returns to the desulfurizer internal pressure decrease confirmation step (S6).

  On the other hand, if the value detected by the pressure gauge 23 is equal to or smaller than the third predetermined value in the step (S11) of determining whether the value is equal to or smaller than the third predetermined value, and the number of times the second shut-off valve 22 is opened and closed. When the predetermined number of times is exceeded in the step of determining whether or not the predetermined number of times has been exceeded (S12), the control unit 60 keeps the second shut-off valve 22 open from the state of repeated opening and closing. Switch to the state (S13). By maintaining the second shut-off valve 22 in an open state when the above conditions are satisfied, an increase in the number of times the second shut-off valve 22 is opened and closed can be suppressed, and the life of the second shut-off valve 22 can be extended. Can do. If the 2nd cutoff valve 22 is maintained in an open state, it will return to a desulfurizer internal pressure fall confirmation process (S6).

  In the desulfurizer internal pressure drop confirmation step (S6), when the value detected by the pressure gauge 23 is equal to or smaller than the second predetermined value, the control unit 60 stops the power generation air blower 43 (S14). Further, the control unit 60 stops the reforming air blower 33 (S15). Moreover, the control part 60 closes the 2nd cutoff valve 22 (S16). In the flow of FIG. 2, the step of stopping the power generation air blower 43 (S14), the step of stopping the reforming air blower 33 (S15), and the step of closing the second shutoff valve 22 (S16) are performed in this order. These three steps (S14, S15, S16) may be performed simultaneously. When the second shut-off valve 22 is closed (S16), the control unit 60 determines whether or not the fuel cell 53 has started operation (S17). When the fuel cell 53 has not started operation, the process returns to the desulfurizer internal pressure detection step (S2), and the above-described flow is performed. On the other hand, when the operation is started in the step (S17) for determining whether or not the fuel cell 53 has started operation, the overpressure elimination control of the desulfurizer 11 ends.

  As described above, according to the fuel cell system 1 according to the present embodiment, the reforming air when the internal pressure of the desulfurizer 11 becomes equal to or higher than the first predetermined value in the overpressure elimination control. Since the second shutoff valve 22 is repeatedly opened and closed while supplying the AR and the power generation air AG, the raw material D discharged from the fuel cell system 1 is diluted to a concentration below the lower combustion limit, and the raw material D is discharged as it is. It is possible to avoid malfunctions of auxiliary equipment that may occur in the event of failure.

  In the above description, the second shut-off valve 22 is an electromagnetic valve, but it may be an electric valve. When the second shut-off valve 22 is an electric valve, the discharge flow rate suppression means can be configured by the controller 60 adjusting the opening degree of the electric valve (the second shut-off valve 22). The accompanying deterioration can be suppressed. On the other hand, when the second cutoff valve 22 is an electromagnetic valve, the response can be accelerated.

  In the above description, the discharge flow rate suppression means is configured by repeating the opening / closing operation of the solenoid valve or adjusting the opening of the motor operated valve, but in the desulfurized raw material pipe 19 on the downstream side of the second shutoff valve 22. A bypass pipe provided with a capillary or an orifice is provided, and the raw material D discharged from the desulfurizer 11 in the overpressure elimination control of the desulfurizer 11 passes through the bypass pipe provided with the capillary or orifice. Also good. If it does in this way, the reliability of suppression of the discharge flow rate of the raw material D can be improved. On the other hand, if the discharge flow rate suppression means is configured by opening / closing operation of the valve or opening degree adjustment, the raw material D can be discharged gently without providing a special device.

  In the above description, when the value detected by the pressure gauge 23 is equal to or greater than the first predetermined value, the reforming air AR and the power generation air AG are supplied. When the raw material D can be diluted to a desired concentration, the power generation air AG need not be supplied.

  In the above description, when the second predetermined time has elapsed from the reference time (Yes in S8) and the decrease in the value detected by the pressure gauge 23 is less than the first predetermined difference (Yes in S9). Although it is assumed that there is some abnormality (S10), instead of the steps (S8, S9) for making these determinations, the value detected by the pressure gauge 23 is changed to the second before the second predetermined difference decreases. When a predetermined time of 3 has elapsed, it may be estimated that there is an abnormality. For example, when it is estimated that there is an abnormality when 5 minutes elapse before the 4 kPa (gauge pressure) decreases, the second predetermined difference is 4 kPa (gauge pressure), and the third predetermined time is 5 minutes. Become. In addition, you may abbreviate | omit a series of processes (S7-S10) for deducing the generation | occurrence | production of abnormality, and in this case, it is not below 2nd predetermined value in a desulfurizer internal pressure fall confirmation process (S6). In this case, the process proceeds to a step (S11) for determining whether or not the value detected by the pressure gauge 23 is equal to or smaller than a third predetermined value.

  In the above description, in order to suppress an increase in the number of times the second shut-off valve 22 is opened and closed, the step (S11) of determining whether or not the value detected by the pressure gauge 23 is equal to or smaller than a third predetermined value, and the second Although the step (S12) of determining whether or not the number of opening / closing operations of the shut-off valve 22 exceeds a predetermined number is performed, one or both of these steps may be omitted. When the step (S12) for determining whether or not the number of opening / closing operations of the second shut-off valve 22 exceeds a predetermined number is omitted, whether or not the value detected by the pressure gauge 23 is equal to or less than a third predetermined value. When it is not less than or equal to the third predetermined value in the step of determining (S11), the process returns to the desulfurizer internal pressure drop confirmation step (S6). Further, when both steps (S11, S12) are omitted, the step (S13) for maintaining the second shut-off valve 22 in an open state is also omitted. When a series of steps (S11 to S13) for guiding the second shutoff valve 22 to be kept open is omitted, a step of determining whether or not a second predetermined time has passed (S8). ) In step (S9) when the second predetermined time has not elapsed and in the step (S9) of determining whether or not the decrease in the value detected by the pressure gauge 23 is less than the first predetermined difference. When it is not less than the difference, the process returns to the desulfurizer internal pressure drop confirmation step (S6). It should be noted that both a series of steps (S7 to S10) for guiding the occurrence of abnormality and a series of steps (S11 to S13) for guiding the second shutoff valve 22 to be kept open. When is omitted, when the desulfurizer internal pressure drop confirmation step (S6) is not less than or equal to the second predetermined value, the process returns to the desulfurizer internal pressure drop confirmation step (S6) again.

DESCRIPTION OF SYMBOLS 1 Fuel cell system 11 Desulfurizer 18 Predesulfurization raw material pipe 19 Desulfurized raw material pipe 21 First shutoff valve 22 Second shutoff valve 23 Pressure gauge 31 Reforming air supply unit 33 Reforming air blower 41 Power generation air supply unit 43 Power generation air blower 51 Reformer 53 Fuel cell 60 Control part D Raw material Dr Raw material before desulfurization Df Desulfurized raw material E Fuel gas AG Power generation air AR Reformation air

Claims (9)

A desulfurizer for producing a desulfurized raw material by desulfurizing a raw material to be desulfurized which is a hydrocarbon-based raw material;
A reforming section for reforming the desulfurized raw material to produce a fuel gas containing hydrogen;
A fuel cell for generating electricity by introducing the fuel gas and air for power generation;
A desulfurization raw material line for guiding the desulfurization raw material to the desulfurizer;
A first shut-off valve provided in the raw material line for desulfurization;
A desulfurized raw material line for guiding the desulfurized raw material from the desulfurizer to the reforming section;
A second shut-off valve provided in the desulfurized raw material line;
A desulfurizer internal pressure detector for directly or indirectly detecting the pressure inside the desulfurizer;
A reforming air supply unit that supplies reforming air to the desulfurized raw material line downstream of the second shutoff valve or to the reforming unit;
When the pressure detected by the desulfurizer internal pressure detector is equal to or higher than a first predetermined value with the first shut-off valve and the second shut-off valve closed, toward the reforming unit. While supplying the reforming air and opening the second shut-off valve, the pressure detected by the desulfurizer internal pressure detector is reduced to a second predetermined value smaller than the first predetermined value. A control unit that operates the reforming air supply unit and the second shut-off valve so as to perform a depressurizing process to be reduced;
Fuel cell system. A power generation air supply unit configured to supply the power generation air to the fuel cell;
The control unit, in addition to supplying the reforming air toward the reforming unit when the pressure detected by the desulfurizer internal pressure detector is equal to or higher than the first predetermined value, Activating the power generation air supply to supply the power generation air to the fuel cell;
The fuel cell system according to claim 1. A discharge flow rate suppressing means for suppressing the discharge flow rate of the raw material to the outside so that the raw material discharged to the outside by the decompression process is discharged to the outside at a concentration less than the lower limit of combustion;
The fuel cell system according to claim 1 or 2. The discharge flow rate suppression means is configured by the control unit repeatedly opening and closing the second shutoff valve;
The fuel cell system according to claim 3. When the pressure detected by the desulfurizer internal pressure detector is equal to or lower than a third predetermined value between the first predetermined value and the second predetermined value, the control unit Configured to keep the shut-off valve open;
The fuel cell system according to claim 4. The control unit is configured to maintain the second shut-off valve in an open state when the number of opening / closing operations of the second shut-off valve exceeds a predetermined number;
The fuel cell system according to claim 4 or 5. The discharge flow rate suppression means is configured by the control unit adjusting the opening of the second shutoff valve;
The fuel cell system according to claim 3. When the pressure detected by the desulfurizer internal pressure detector exceeds the second predetermined value when the first predetermined time has elapsed since the start of the pressure reduction process, Configured to presume that there is an anomaly;
The fuel cell system according to any one of claims 1 to 7. The control unit, while performing the pressure reduction process, when the decrease in pressure detected by the desulfurizer internal pressure detector within a second predetermined time is less than a first predetermined difference, or Configured to estimate that there is an abnormality when a third predetermined time has elapsed before the pressure detected by the desulfurizer internal pressure detector decreases by a second predetermined difference;
The fuel cell system according to any one of claims 1 to 8.

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