Fuel cell system and fuel cell system operating method

Abstract

To suppress water adsorption of a desulfurization agent that desulfurizes a material gas supplied to a fuel cell.SOLUTION: A fuel cell system 10 comprises: an FC (fuel cell) stack 42 that generates power with a fuel gas supplied to an anode 42A and air supplied to a cathode 42B; a desulfurizer 12 provided at an upstream side from the anode 42A to remove a sulfur component from gas supplied from a gas piping 41; a dew point meter 11 provided at an upstream side from the desulfurizer 12 to measure a dew point of gas flowing through the gas piping 41; and a gas supply control unit 48 that stops gas supply from piping 4 to the desulfurizer 12 when the dew point measured by the dew point meter 11 becomes larger than a threshold TH1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a fuel cell system and a method for operating the fuel cell system. [Background technology]

[0002] A desulfurizing agent that adsorbs sulfur from the feed gas is installed in the gas path of a fuel cell system that receives a supply of sulfur-added feed gas. By removing sulfur from the feed gas, sulfur poisoning of the reforming catalyst is suppressed, and normal operation of the fuel cell system is maintained.

[0003] In Patent Document 1, maintenance (replacement) of the desulfurizers is encouraged by providing information regarding maintenance of the first desulfurizer and the second desulfurizer based on the dew point of the raw material gas and the cumulative flow rate of the raw material gas flowing through the raw material gas passage from a reference time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-169044 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, this desulfurizing agent has a characteristic that, when gas containing a relatively large amount of water is supplied, it adsorbs more water than sulfur, and desorbs the adsorbed sulfur.

[0006] Therefore, if water flows into the gas pipeline upstream of the gas supply area due to some force majeure, such as gas construction work, gas containing water will be supplied to the fuel cell system, and the sulfur adsorbed to the desulfurizing agent will be released by the adsorption of water, causing sulfur poisoning of the reforming catalyst, fuel cell stack, etc., which may affect the normal operation of the fuel cell system.

[0007] Patent Document 1 does not consider and cannot deal with cases where sulfur adsorbed on the desulfurizing agent is released. On the other hand, there is a problem as to how to deal with cases where gas that temporarily contained water no longer contains water.

[0008] The present invention has been made in consideration of the above circumstances, and has as its object to suppress the desorption of sulfur content due to water adsorption by a desulfurizing agent that desulfurizes raw material gas supplied to a fuel cell. [Means for solving the problem]

[0009] The fuel cell system of claim 1 includes a fuel cell that generates electricity using fuel gas supplied to an anode and air supplied to an cathode, a desulfurizer that is provided upstream of the anode and removes sulfur components from gas supplied from a gas pipe, a dew point meter that is provided upstream of the desulfurizer and measures the dew point of the gas flowing through the gas pipe, and a gas supply control unit that stops the supply of gas from the gas pipe to the desulfurizer when the dew point measured by the dew point meter exceeds a water contamination value.

[0010] In the fuel cell system according to claim 1, when the dew point measured by the dew point meter exceeds the water contamination value, the gas supply control unit stops the gas supply from the gas piping to the desulfurizer. This prevents water-contaminated gas from flowing into the desulfurizer, making it possible to suppress desorption of sulfur content due to water adsorption on the desulfurizing agent.

[0011] In the fuel cell system of claim 2, the gas supply control unit stops the gas supply from the gas piping to the desulfurizer, and then resumes the gas supply from the gas piping to the desulfurizer when it determines that the gas supplied to the gas piping is in a water-free state where water contamination has been eliminated.

[0012] According to the fuel cell system of claim 2, after the gas supply from the gas piping to the desulfurizer is stopped, if the gas supply control unit determines that the gas supplied to the gas piping has been freed from water contamination, the gas supply from the gas piping to the desulfurizer is resumed, thereby enabling the fuel cell system to be operated appropriately.

[0013] In the fuel cell system according to claim 3, the gas supply control unit supplies gas from the gas piping to the dew point meter at a predetermined normality confirmation time after the gas supply from the gas piping to the desulfurizer is stopped, and determines that the water contamination has been eliminated when the dew point measured by the dew point meter drops to within a normal range.

[0014] In this way, when the dew point measured by the dew point meter drops to within the normal range, it can be determined that the water contamination has been eliminated.

[0015] In the fuel cell system according to claim 4, the gas supply control unit determines that the water contamination has been eliminated when a notification to that effect is received via a network.

[0016] In this way, when a notification that the water contamination has been eliminated is received via the network, it can be determined that the water contamination has been eliminated.

[0017] The fuel cell system of claim 5 has a purge flow path branched off from the gas pipe at a branching section upstream of the desulfurizer, and when the gas supply control unit determines that the gas being supplied to the gas pipe has been cleaned of water contamination after stopping the gas supply from the gas pipe to the desulfurizer, the gas supply control unit switches the gas in the gas pipe to be supplied to the purge flow path to purge the gas in the gas pipe before resuming the gas supply from the gas pipe to the desulfurizer.

[0018] In the fuel cell system according to claim 5, before restarting the gas supply from the gas pipe to the desulfurizer, the gas in the gas pipe is purged by switching the gas supply to the purge flow path, thereby preventing gas containing water from being supplied to the desulfurizer.

[0019] In the fuel cell system according to claim 6, the dew point meter is provided upstream of the branching portion, and the gas supply control unit supplies gas from the gas piping to the dew point meter at predetermined normality confirmation times after the gas supply from the gas piping to the desulfurizer is stopped, and supplies gas from the gas piping to the dew point meter to the purge flow path via the dew point meter at the normality confirmation times.

[0020] According to the fuel cell system of claim 6, after the gas supply from the gas piping to the desulfurizer is stopped, when gas is supplied from the gas piping to the dew point meter at a preset normality confirmation time to determine whether it is within the normal range, it is possible to avoid supplying gas to the desulfurizer.

[0021] A fuel cell system according to a seventh aspect of the present invention includes a reformer that reforms the gas supplied from the gas pipe and a combustor that raises the temperature of the reformer, and the purge passage is connected to the combustor.

[0022] According to the fuel cell system of claim 7, the water-mixed gas can be burned in the combustor that heats the reformer.

[0023] In the fuel cell system according to claim 8, the purge passage is connected to a combustor of a heat source unit.

[0024] According to the fuel cell system of claim 8, the water-mixed gas can be subjected to combustion in the combustor of the heat source device.

[0025] The fuel cell system operating method according to claim 9 is a method for operating a fuel cell system in which gas is supplied via a desulfurizer to a fuel cell that generates electricity using fuel gas supplied to an anode and air supplied to an cathode, and when the dew point of gas flowing through a gas piping upstream of the desulfurizer exceeds a water contamination value, the gas supply from the gas piping to the desulfurizer is stopped.

[0026] In the fuel cell system operating method according to claim 9, when the dew point of the gas flowing through the gas piping upstream of the desulfurizer exceeds the water contamination value, the gas supply from the gas piping to the desulfurizer is stopped. This prevents water-contaminated gas from flowing into the desulfurizer, thereby suppressing the desorption of sulfur content due to water adsorption by the desulfurizing agent.

[0027] The fuel cell system operating method according to claim 10 resumes the supply of gas from the gas piping to the desulfurizer after stopping the supply of gas from the gas piping to the desulfurizer, if it is determined that the gas being supplied to the gas piping has been cleared of water contamination.

[0028] According to the fuel cell system operating method of claim 10, after the gas supply from the gas piping to the desulfurizer is stopped, if it is determined that the gas supplied to the gas piping has been freed from water contamination, the gas supply from the gas piping to the desulfurizer is resumed, thereby enabling the fuel cell system to be operated appropriately.

[0029] In the fuel cell system operating method according to claim 11, after stopping the gas supply from the gas piping to the desulfurizer, if it is determined that the gas supplied to the gas piping is in a water-free state in which water contamination has been eliminated, the gas in the gas piping is purged to a part other than the desulfurizer before resuming the gas supply from the gas piping to the desulfurizer.

[0030] According to the fuel cell system operating method of claim 11, before restarting the gas supply from the gas pipe to the desulfurizer, the gas in the gas pipe is purged to a portion other than the desulfurizer, thereby preventing the supply of gas containing water to the desulfurizer. [Effects of the Invention]

[0031] According to the fuel cell system and the method for operating the fuel cell system of the present invention, it is possible to suppress the desorption of sulfur content due to water adsorption by the desulfurizing agent that desulfurizes the raw material gas supplied to the fuel cell. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is an overall view of a fuel cell operation management system according to a first embodiment. [Figure 2] 10 is an example of area information corresponding to each gas pipe. [Figure 3] 1 is a configuration diagram of a fuel cell system according to a first embodiment. [Figure 4] 1 is a configuration diagram of a fuel cell operation management device according to a first embodiment. [Figure 5] 4 is a flowchart of a dew-point adaptive operation process according to the first embodiment. [Figure 6] 4 is a flowchart of a water status confirmation process according to the first embodiment. [Figure 7] 4 is a flowchart of a purge process according to the first embodiment. [Figure 8] FIG. 10 is a configuration diagram of a fuel cell system according to a second embodiment. [Figure 9] 10 is a flowchart of a water status confirmation process according to the second embodiment. [Figure 10] 10 is a flowchart of a purge process according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] First Embodiment A first embodiment of the present invention will be described with reference to the drawings.

[0034] (Overall configuration of fuel cell operation management system S) Fig. 1 is a schematic diagram of a fuel cell operation management system S that manages the operation of a fuel cell system 10 according to this embodiment. The fuel cell operation management system S shown in Fig. 1 is an operation management system for a plurality of fuel cell systems 10 installed at various locations, and includes a fuel cell operation management device 20 and the fuel cell systems 10 installed at various locations.

[0035] The fuel cell operation management device 20 is a device that collects water contamination information and location information of water-contaminated gas conduits from each fuel cell system 10, and sends instructions to stop or cancel the shutdown to the fuel cell systems 10 that are affected by the water contamination. The fuel cell operation management device 20 and the fuel cell systems 10 are connected to a network N and are capable of communicating with each other. The network N is, for example, the Internet.

[0036] The fuel cell system 10 is, for example, ENE-FARM (registered trademark). The fuel cell system 10 is installed in a user's home, an apartment building, a factory, etc. As shown in FIG. 2 , each fuel cell system 10 has area information J registered for each gas conduit 28A, 28B, 28C, etc. that supplies gas to a low-pressure area. For example, "area information JA" is registered for a fuel cell system 10 installed in an area that receives gas supply from gas conduit 28A, and "area information JB" is registered for a fuel cell system 10 installed in an area that receives gas supply from gas conduit 28B. The fuel cell system 10 is connected to a network N. Details of the fuel cell system 10 will be described later.

[0037] City gas to which sulfur components have been added flows through the gas conduit 28. Note that, although the present embodiment will be described taking city gas as an example, the present invention can also be applied to other gas piping through which gas containing hydrocarbon components flows.

[0038] (Configuration of fuel cell system 10) 3, the fuel cell system 10 includes a dew point meter 11, a desulfurizer 12, a reformer 40, a fuel cell stack 42 (hereinafter referred to as "FC stack 42"), a burner 44, an FC control unit 45, an operation panel 52, and a communication unit 54. Raw material gas whose pressure has been reduced via a pressure regulator (not shown) is supplied to the fuel cell system 10 from a gas conduit 28 via a gas piping 41.

[0039] To the gas pipe 41, from the upstream side, a dew point meter 11, a desulfurizer 12, a reformer 40, and an FC stack 42 are connected. The dew point meter 11 measures the dew point of the raw material gas. The desulfurizer 12 is filled with a desulfurizing agent, which adsorbs and removes sulfur components added to the raw material gas. This makes it possible to suppress sulfur poisoning in the reformer 40 and the FC stack 42.

[0040] An electromagnetic valve V1 is provided upstream of the dew point meter 11. The supply and stop of the raw material gas from the gas pipe 41 is controlled by opening and closing the electromagnetic valve V1.

[0041] A blower B1 is provided downstream of the dew point meter 11 and upstream of the desulfurizer 12. The blower B1 sends out the raw material gas downstream in accordance with the amount of power generated by the fuel cell system .

[0042] A reformer 40 is provided downstream of the desulfurizer 12. The reformer 40 contains a reforming catalyst and reforms the raw material gas into a fuel gas containing hydrogen.

[0043] The FC stack 42 has a plurality of stacked fuel cell units. Various fuel cells can be used as the fuel cell units that make up the FC stack 42, such as solid oxide fuel cells (SOFCs), molten carbonate fuel cells (MCFCs), and polymer electrolyte fuel cells (PEFCs). Each fuel cell unit of the FC stack 42 has an electrolyte membrane and an anode (fuel electrode) 42A and a cathode (air electrode) 42B that are stacked on the front and back sides of the electrolyte membrane, respectively. The fuel gas produced in the reformer 40 is supplied to the anode 42A. Air is supplied to the cathode 42B from an air blower (not shown). Power generation reactions occur in the anode 42A and the cathode 42B, and the power is output to a circuit (not shown).

[0044] The burner 44 is provided downstream of the FC stack 42, and is supplied with the anode offgas discharged from the anode 42A and the cathode offgas discharged from the cathode 42B. In the burner 44, combustible components in the anode offgas are burned by the oxygen in the cathode offgas. The combustion heat in the burner 44 can be used to heat the reformer 40.

[0045] A purge flow path 50 is branched off from the gas pipe 41 downstream of the blower B1 and upstream of the desulfurizer 12. A solenoid valve V2 is provided in the purge flow path 50. The purge flow path 50 is connected to the burner 44. By opening and closing the solenoid valves V1 and V2, the supply destination of the raw material gas from the gas pipe 41 can be switched between the desulfurizer 12 side and the burner 44 side.

[0046] The FC control unit 45 is a computer that controls each part of the fuel cell system 10, and is connected to the dew point meter 11, the solenoid valves V1 and V2, the blower B1, and other parts of the fuel cell system 10 (not shown).

[0047] The FC control unit 45 includes, as hardware, a processor 46 and a memory 47. The processor 46 includes a CPU (Central Processing Unit), etc. The memory 47 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and storage, etc.

[0048] The ROM stores various programs and various data. The RAM temporarily stores programs or data as a working area. The storage is composed of an HDD (Hard Disk Drive) or an SSD (Solid State Drive), etc., and stores various programs including an operating system and various data. The ROM or storage stores a program for controlling the fuel cell system 10. The processor 46 reads out the program 47A and executes the program 47A using the RAM as a working area.

[0049] The memory area 47B of the memory 47 stores area information J of the fuel cell system 10, a threshold value TH1 as a water contamination value at which abnormal water contamination is suspected, a threshold value TH2 for confirming that the abnormal water contamination has been resolved, etc., as well as operating data output from each part within the fuel cell system 10 and dew point data output from the dew point meter 11, etc.

[0050] Here, the threshold value TH1 at which abnormal water contamination is suspected is set to a value at which the dew point in the gas flowing through the gas piping 41 becomes high and abnormal water contamination is suspected. The threshold value TH2 for confirming that the abnormal water contamination has been resolved is a value at which it can be confirmed that the dew point that once became abnormally high has returned to normal, and is set lower than the threshold value TH1.

[0051] The processor 46 includes, as a functional component, a gas supply control unit 48. The function of the gas supply control unit 48 is realized by the processor 46 executing a program 47A.

[0052] The operation panel 52 has a display, lamps, switches, etc. The operation panel 52 has switches that can change the operation and settings of the fuel cell system 10. The communication device 54 is, for example, a modem. The communication device 54 has a function of connecting the fuel cell operation management device 20 (described later) and the FC control unit 45 via the network N so that they can communicate with each other.

[0053] The dew point meter 11 outputs the measured dew point value as dew point data to the FC control unit 45. When the water vapor concentration in the raw material gas increases and the dew point data value becomes equal to or greater than a threshold value TH1 indicating a suspected abnormal water contamination, the FC control unit 45 transmits this as water contamination information together with area information J of the fuel cell system 10 via the network N to the fuel cell operation management device 20.

[0054] (Configuration of fuel cell operation management device 20) As shown in Fig. 4, the fuel cell operation management device 20 includes an input device 22 and a computer 23. The input device 22 is, for example, a keyboard or a touch panel. The computer 23 includes, as hardware, a processor 24, a memory 25, a database 26, and a communication interface 27. The basic configurations of the processor 24 and the memory 25 are similar to those of the processor 46 and memory 47 of the FC control unit 45 described above (see Fig. 2).

[0055] The memory 25 stores a program 28P for managing the operation of the fuel cell system 10 installed in the management area. The database 26 stores in advance information (including area information J) about the fuel cell system 10 in the management area.

[0056] The communication interface 27 has a function of connecting the fuel cell system 10 and the computer 23 via the network N so that they can communicate with each other.

[0057] The computer 23 has, as functional components, a water contamination information collecting unit 24A, a fuel cell identifying unit 24B, and an operation stop instruction transmitting unit 24C. These functional units are realized by the processor 24 executing the program 28.

[0058] The water contamination information collecting unit 24A has a function of storing water contamination information about water contamination in the gas conduit 28 and location information of the water-contaminated gas conduit 28W in association with each other in the database 26. The water contamination information and the location information of the water-contaminated gas conduit 28W include information from inquiries from users and contacts from contractors.

[0059] When the information source is an inquiry from a user or a contact from a contractor, the operator inputs water contamination information and location information of the water-contaminated gas conduit 28W into the input device 22. In the case of an inquiry from a user, the location information for the water-contaminated gas conduit 28W is the area information J in which the user is located. In the case of a contact from a contractor, the location information is information corresponding to the content of the contact. For example, if water is found in a gas conduit during gas construction work, the location information is the ID information of the gas conduit 28 affected by the gas construction work.

[0060] The fuel cell identification unit 24B has a function of identifying the fuel cell system 10 to which gas is supplied from the water-mixed gas conduit 28W. The operation stop instruction transmission unit 24C has a function of transmitting an operation stop instruction to the fuel cell system 10 identified by the fuel cell identification unit 24B.

[0061] Next, the operation of the fuel cell system 10 of this embodiment will be described.

[0062] During power generation operation of the fuel cell system 10, solenoid valve V1 is open and solenoid valve V2 is closed. City gas supplied from gas conduit 28 to gas piping 41 is sent by blower B1 to desulfurizer 12, which removes sulfur components from the city gas. The city gas desulfurized in desulfurizer 12 is reformed in reformer 40 to produce fuel gas containing hydrogen. The fuel gas is supplied to the anode 42A of the FC stack 42, where a power generation reaction occurs together with air supplied to the cathode 42B to generate electricity, which is then extracted via a line (not shown). The off-gas from the anode 42A and cathode 42B is sent to burner 44 and combusted.

[0063] During power generation operation of the fuel cell system 10, the dew point meter 11 measures the dew point of the gas pipe 41 and outputs the measurement result as dew point data to the FC control unit 45. The FC control unit 45 stores the received dew point data together with the input date and time in the storage area 47B of the memory 47. Then, the dew point adaptive operation process shown in FIG. 5 is read from the memory 47 and executed by the processor 46.

[0064] First, in step S10, the latest dew point data is read from storage area 47B, and in step S11, it is determined whether the dew point data is equal to or greater than threshold value TH1. If the dew point data is less than threshold value TH1, the process returns to step S10.

[0065] If the dew point data is equal to or greater than the threshold value TH1, in step S12, the water intrusion information is sent to the fuel cell operation management device 20 together with the area information J of the fuel cell system 10. As a result, the water intrusion information and the area information J are registered in the fuel cell operation management device 20.

[0066] Next, in step S13, the solenoid valve V1 is closed, and in step S14, power generation by the fuel cell system 10 is stopped. This stops the supply of gas containing water, and makes it possible to prevent water from being adsorbed by the desulfurizing agent in the desulfurizer 12.

[0067] Next, in step S20, a water status confirmation process is executed. As shown in Fig. 6, the water status confirmation process first determines in step S21 whether water contamination elimination information has been received. The water contamination elimination information is information transmitted from the fuel cell operation management device 20, and when the fuel cell operation management device 20 receives water contamination elimination information together with area information J, the water contamination elimination information is information that is transmitted to the fuel cell systems 10 installed within the area of ​​the corresponding area information J. If water contamination elimination information has been received in step S21, the water status confirmation process ends.

[0068] If the water contamination elimination information has not been received, it is determined in step S22 whether the normality confirmation time T has elapsed. The normality confirmation time T is the interval for checking the water contamination state after power generation by the fuel cell system 10 is stopped in step S14, and is set in advance to, for example, 30 minutes or 1 hour. The normality confirmation time T may be a fixed time, or may be shortened each time the determination is made. For example, it may be set to 1 hour for the first to third times in the flow, 30 minutes for the fourth to sixth times, 10 minutes for the seventh time onwards, etc. If the normality confirmation time T has not elapsed, the process returns to step S21.

[0069] If the normality confirmation time T has elapsed, in step S23, the solenoid valve V2 is opened. This causes city gas to flow from the gas pipe 41 to the purge flow path 50, and the dew point of the flowing city gas is measured by the dew point meter 11 and stored in the memory area 47B. In step S24, the latest dew point data is read from the memory area 47B, and in step S25, the solenoid valve V2 is closed. Because the solenoid valve V2 is temporarily opened to collect the dew point data and then closed after a short time, only a small amount of city gas is supplied to the purge flow path 50.

[0070] In step S26, it is determined whether the dew point data is equal to or lower than threshold value TH2. If the determination is negative, the process returns to step S21. If the determination is positive, it can be determined that the dew point is normal and the water contamination has been eliminated, so in step S27, water contamination elimination information is sent to the fuel cell operation management device 20 along with area information J, and the water status confirmation process is terminated. Having received the water contamination elimination information, the fuel cell operation management device 20 transmits the water contamination elimination information together with area information J via network N to the fuel cell systems 10 installed within the area of ​​the corresponding area information J.

[0071] Next, the purge process is executed in step S30 (FIG. 5). In the purge process, as shown in FIG. 7, the solenoid valve V2 is opened in step S32. This causes city gas that may be contaminated with water to flow from the gas pipe 41 to the purge flow path 50. In step S34, the system waits until the purge time has elapsed. The purge time is the time required for the city gas that may be contaminated with water in the gas pipe 41 to be replaced with city gas that is not contaminated with water, and is set in advance.

[0072] After it is determined in step S34 that the purge time has elapsed, the solenoid valve V2 is closed in step S36, and the purge process ends. This purge process allows the water-containing gas remaining upstream of the branch point in the gas pipe 41 to be discharged.

[0073] Next, in step S15 (FIG. 5), the solenoid valve V1 is opened, and in step S16, power generation by the fuel cell system 10 is resumed, and the dew-point adaptive operation process is completed.

[0074] In the fuel cell system 10 of this embodiment, when the dew point data from the dew point meter 11 is equal to or greater than a threshold value TH1 indicating a suspected abnormal water contamination, the gas supply to the desulfurizer 12 is stopped. This prevents the water-containing gas from flowing into the desulfurizer 12, thereby suppressing water adsorption by the desulfurizing agent. This also suppresses the discharge of sulfur components caused by water adsorption by the desulfurizing agent.

[0075] Furthermore, after the gas supply to the desulfurizer 12 is stopped and power generation in the fuel cell system 10 is stopped, a small amount of gas is passed through the purge flow path every normality confirmation time T, and the dew point is measured by the dew point meter 11, so that the water contamination state after shutdown can be monitored. When the measured dew point becomes equal to or less than the threshold value TH2 for confirming elimination of abnormal water contamination, it is determined that the system has returned to normal and the abnormal water contamination has been eliminated, and power generation operation of the fuel cell system 10 can be automatically resumed.

[0076] In addition, before the power generation operation of the fuel cell system 10 is resumed, the gas in the gas piping 41 is purged to the purge passage 50 and sent to the burner 44, thereby preventing gas containing water from flowing into the desulfurizer 12.

[0077] Although the purge flow path 50 is provided in this embodiment, the purge flow path 50 does not have to be provided. If the purge flow path 50 is not provided, in the water status confirmation process of step S20, the solenoid valve V1 is opened in step S23 and closed in step S25. Furthermore, the purge process of step S30 is not executed. Even in such a case, the amount of water-mixed gas sent to the desulfurizer 12 is small, so that the release of sulfur components from the desulfurizing agent in the desulfurizer 12 can be suppressed.

[0078] Second Embodiment Next, a second embodiment of the present invention will be described. In this embodiment, the same parts as in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

[0079] The fuel cell system 70 of this embodiment has an external purge passage 51 instead of the purge passage 50 of the fuel cell system 10 of the first embodiment. The configuration other than the external purge passage 51 is the same as that of the fuel cell system 10 of the first embodiment.

[0080] 8, the fuel cell system 70 includes an external purge flow path 51. The external purge flow path 51 is branched and connected downstream of the blower B1 and upstream of the desulfurizer 12. A solenoid valve V3 is provided in the external purge flow path 51. The solenoid valve V3 is connected to the FC control unit 45, and its opening and closing is controlled.

[0081] The downstream end of the external purge flow path 51 is connected to a burner 60A in a heat source device 60. The heat source device 60 is a device such as a gas water heater or a floor heating system that uses combustion heat from the burner 60A as a heat source for heat exchange with water. By opening and closing the solenoid valves V1 and V3, the destination of the gas supply from the gas pipe 41 can be switched to either the desulfurizer 12 side or the burner 44 side.

[0082] Next, the operation of the fuel cell system 70 of this embodiment will be described.

[0083] During the power generation operation of the fuel cell system 70, the solenoid valve V1 is open and the solenoid valve V3 is closed.

[0084] During power generation operation of the fuel cell system 70, the dew point meter 11 measures the dew point of the gas pipe 41 and outputs the measurement result as dew point data to the FC control unit 45. The FC control unit 45 stores the received dew point data together with the input date and time in the storage area 47B of the memory 47. The dew point adaptive operation process shown in Fig. 5 is then read from the memory 47 and executed by the processor 46. In the dew point adaptive operation process, the water status confirmation process is performed according to the flow shown in Fig. 9.

[0085] First, in step S21, it is determined whether or not water contamination elimination information has been received. If water contamination elimination information has been received, the water status confirmation process ends. If water contamination elimination information has not been received, it is determined in step S22 whether or not the normality confirmation time T has elapsed. If the normality confirmation time T has not elapsed, the process returns to step S21.

[0086] If the normality confirmation time T has elapsed, in step S28, the solenoid valve V3 is opened. This causes city gas to flow from the gas pipe 41 to the external purge flow path 51, and the dew point of the flowing city gas is measured by the dew point meter 11 and stored in the memory area 47B. In step S24, the latest dew point data is read from the memory area 47B, and in step S29, the solenoid valve V3 is closed. Because the solenoid valve V3 is opened temporarily to collect the dew point data and then closed after a short time, the amount of city gas supplied to the external purge flow path 51 is small.

[0087] In step S26, it is determined whether the dew point data is equal to or less than the threshold value TH2. If the determination is negative, the process returns to step S21. If the determination is positive, it can be determined that the dew point is equal to or less than the threshold value TH2 and that the water contamination has been resolved, so in step S27, the water contamination elimination information is sent to the fuel cell operation management device 20 together with the area information J, and the water status confirmation process is terminated.

[0088] Next, the purge process of step S30 (FIG. 5) is executed. In the purge process, as shown in FIG. 10, the solenoid valve V3 is opened in step S33. This causes city gas that may be contaminated with water to flow from the gas pipe 41 to the external purge flow path 51. In step S35, the system waits until the purge time has elapsed. The purge time is the time required for the city gas that may be contaminated with water in the gas pipe 41 to be replaced with city gas that is not contaminated with water, and is set in advance.

[0089] After it is determined in step S34 that the purge time has elapsed, the solenoid valve V3 is closed in step S35, and the purge process ends. This purge process allows the water-containing gas remaining upstream of the branch point in the gas pipe 41 to be discharged.

[0090] Thereafter, in step S15 (FIG. 5), the solenoid valve V1 is opened, and in step S16, power generation by the fuel cell system 10 is resumed, and the dew-point adaptive operation process is completed.

[0091] In the fuel cell system 70 of this embodiment, when the dew point data from the dew point meter 11 is equal to or greater than the threshold value TH1 indicating a suspected abnormal water contamination, the gas supply to the desulfurizer 12 is stopped. This prevents the water-containing gas from flowing into the desulfurizer 12, thereby suppressing water adsorption to the desulfurizing agent. This also suppresses the discharge of sulfur components due to water adsorption to the desulfurizing agent.

[0092] Furthermore, after the gas supply to the desulfurizer 12 is stopped and power generation in the fuel cell system 10 is stopped, a small amount of gas is passed through the purge flow path every normality confirmation time T, and the dew point is measured by the dew point meter 11, so that the water contamination state after shutdown can be monitored. When the measured dew point becomes equal to or less than the threshold value TH2 for confirming elimination of abnormal water contamination, it is determined that the system has returned to normal and the abnormal water contamination has been eliminated, and power generation operation of the fuel cell system 10 can be automatically resumed.

[0093] In addition, before the power generation operation of the fuel cell system 10 is resumed, the gas in the gas piping 41 is purged to the external purge passage 51 and sent to the burner 44, thereby preventing gas containing water from flowing into the desulfurizer 12.

[0094] The above describes an embodiment of the present invention, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modified forms within the scope of the gist of the present invention. [Explanation of symbols]

[0095] 10, 70 Fuel cell system 11 Dew point meter 12 Desulfurizer 40 Reformer 41 Gas piping 42 Fuel cell stack (fuel cell) 42A anode (fuel electrode) 42B Cathode (air electrode) 44 Burner (combustor) 45 FC control unit (gas supply control unit) 48 Gas supply control unit 50 Purge flow path 51 External purge flow path (purge flow path) 60 Heat source machine 60A burner (combustor) T Normality confirmation time TH1 threshold (water contamination value) TH2 threshold (normal range) V1, V2, V3 solenoid valves (gas supply control unit)

Claims

1. a fuel cell that generates electricity using a fuel gas supplied to the fuel electrode and air supplied to the air electrode; a desulfurizer that is provided upstream of the fuel electrode and removes sulfur components from the gas supplied from a gas pipe; a dew point meter provided upstream of the desulfurizer for measuring the dew point of the gas flowing through the gas pipe; a gas supply control unit that stops the gas supply from the gas piping to the desulfurizer when the dew point measured by the dew point meter exceeds a water contamination value; Equipped with After stopping the gas supply from the gas piping to the desulfurizer, the gas supply control unit resumes the gas supply from the gas piping to the desulfurizer when it determines that the gas supplied to the gas piping is in a water contamination-free state in which water contamination has been eliminated, a purge flow path branched at a branching portion from the gas pipe leading to the desulfurizer on the upstream side of the desulfurizer, When the gas supply control unit determines that the water contamination in the gas supplied to the gas piping has been eliminated after stopping the gas supply from the gas piping to the desulfurizer, the gas supply control unit switches the gas in the gas piping to be supplied to the purge flow path to purge the gas in the gas piping before restarting the gas supply from the gas piping to the desulfurizer. Fuel cell system.

2. After the gas supply from the gas piping to the desulfurizer is stopped, the gas supply control unit executes gas supply from the gas piping to the dew point meter at predetermined normality confirmation time intervals, and determines that the water contamination has been eliminated when the dew point measured by the dew point meter drops to a normal range. The fuel cell system according to claim 1 .

3. the gas supply control unit determines that the water contamination has been eliminated when a notification indicating that the water contamination has been eliminated is received via a network; The fuel cell system according to claim 1 .

4. The dew point meter is provided upstream of the branching portion, After the gas supply from the gas piping to the desulfurizer is stopped, the gas supply control unit executes the gas supply from the gas piping to the dew point meter at predetermined normality confirmation times, and executes the gas supply from the gas piping to the purge flow path via the dew point meter at the normality confirmation times. The fuel cell system according to any one of claims 1 to 3.

5. a reformer that reforms the gas supplied from the gas pipe and a combustor that heats the reformer; The purge passage is connected to the combustor. The fuel cell system according to any one of claims 1 to 4.

6. The purge flow path is connected to a combustor of a heat source machine. The fuel cell system according to any one of claims 1 to 4.

7. The fuel cell generates electricity using fuel gas supplied to the anode and air supplied to the cathode.

1. A method for operating a fuel cell system to which gas is supplied via a sulfurizer, comprising: When the dew point of the gas flowing through the gas piping upstream of the desulfurizer exceeds a water contamination value, the gas supply from the gas piping to the desulfurizer is stopped, After stopping the gas supply from the gas piping to the desulfurizer, if it is determined that the gas supplied to the gas piping is in a water contamination-free state in which water contamination has been eliminated, the gas supply from the gas piping to the desulfurizer is resumed, After stopping the gas supply from the gas piping to the desulfurizer, if it is determined that the water contamination in the gas supplied to the gas piping has been eliminated, the gas in the gas piping is purged to a portion other than the desulfurizer before restarting the gas supply from the gas piping to the desulfurizer. A method for operating a fuel cell system.

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