Control method, control device, and power generation system for fuel cell equipment

Abstract

Unlike conventional methods, this invention provides a control method for a fuel cell system that can perform appropriate control while taking into account the heat demand of consumers. [Solution] The fuel cell system includes at least one fuel cell unit. A control method for the fuel cell system of the present disclosure controls a purge valve for discharging anode off-gas from a recycling path for supplying anode off-gas of the fuel cell unit to the anode, based on the ratio of the heat demand to the electricity demand of the customer or the heat demand of the customer.

Description

[Technical Field]

[0001] This disclosure relates to a control method, control device, and power generation system for a fuel cell device. [Background technology]

[0002] Patent Document 1 discloses a fuel cell system comprising: a fuel cell in which a fuel electrode and an oxidizer electrode are arranged opposite each other with an electrolyte membrane in between; a gas supply means for supplying oxidizer gas and hydrogen gas as fuel to the fuel cell; a recirculation means for returning the hydrogen gas discharged from the fuel cell back to the inlet of the fuel cell; a purge valve for discharging nitrogen-containing hydrogen gas from a recirculation path connecting a hydrogen gas discharge path from the fuel cell and a hydrogen gas supply path supplied to the fuel cell; a concentration detection means for detecting the nitrogen concentration in the hydrogen system of the hydrogen gas supply path and discharge path; and a control means for adjusting and controlling the opening degree of the purge valve so that the nitrogen concentration detected by the concentration detection means is kept substantially constant. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2004-185974 [Overview of the project] [Problems that the invention aims to solve]

[0004] As an example, this disclosure aims to provide a control method, control device, and power generation system for a fuel cell device that, unlike conventional methods, takes into account the heat demand of consumers. [Means for solving the problem]

[0005] To solve the above problems, a control method according to an aspect of the present disclosure is a control method for a fuel cell device including at least one fuel cell unit, and controls a purge valve for discharging anode off-gas from a recycle path for supplying the anode off-gas of the fuel cell unit to the anode based on the ratio of the heat demand to the power demand of the consumer or the heat demand of the consumer.

[0006] Further, a control device according to an aspect of the present disclosure is a control device for a fuel cell device including at least one fuel cell unit, and includes a storage for storing the ratio of the heat demand to the power demand of the consumer or the heat demand of the consumer, and a controller for controlling a purge valve for discharging anode off-gas from a recycle path for supplying the anode off-gas of the fuel cell unit to the anode based on the ratio of the heat demand to the power demand of the consumer or the heat demand of the consumer.

[0007] Further, a power generation system according to an aspect of the present disclosure includes a fuel cell device including at least one fuel cell unit and the control device according to an aspect of the present disclosure.

Advantages of the Invention

[0008] The control method, control device, and power generation system of a fuel cell device according to an aspect of the present disclosure have an effect that, unlike the conventional ones, appropriate control considering the heat demand of the consumer can be performed.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a diagram showing an example of a power generation system according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the control device of FIG. 1. [Figure 3A] FIG. 3A is a flowchart showing an example of the operation of the control device (control method of the fuel cell device) in the power generation system according to the first embodiment. [Figure 3B]Figure 3B is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the first embodiment. [Figure 4A] Figure 4A is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the first embodiment of the first embodiment. [Figure 4B] Figure 4B is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the second embodiment of the first embodiment. [Figure 5A] Figure 5A is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the third embodiment of the first embodiment. [Figure 5B] Figure 5B is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the fourth embodiment of the first embodiment. [Figure 6A] Figure 6A is a diagram illustrating the voltage-time change of the fuel cell device corresponding to the opening and closing of the purge valve in the power generation system of the first embodiment. [Figure 6B] Figure 6B is a diagram illustrating the voltage-time change of the fuel cell device corresponding to a decrease in the opening frequency of the purge valve of the fuel cell device in the power generation system of the first embodiment. [Figure 7] Figure 7 shows an example of a power generation system according to the second embodiment. [Figure 8A] Figure 8A is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the second embodiment. [Figure 8B] Figure 8B is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the second embodiment. [Figure 9A] Figure 9A is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the waste heat up mode of the power generation system of the second embodiment. [Figure 9B]Figure 9B is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the waste heat up mode of the power generation system of the second embodiment. [Figure 10A] Figure 10A is a diagram illustrating the voltage-time change of the fuel cell unit corresponding to the opening and closing of the purge valve in the waste heat up mode of the power generation system of the second embodiment. [Figure 10B] Figure 10B is a diagram illustrating the voltage-time change of the fuel cell unit corresponding to the decrease in the frequency of opening the purge valve in the waste heat up mode of the power generation system of the second embodiment. [Modes for carrying out the invention]

[0010] Patent Document 1 discloses controlling a purge valve for discharging anode off-gas from the hydrogen circulation path so that the nitrogen concentration in the anode off-gas detected by a detector installed in the hydrogen circulation path remains approximately constant. In other words, by employing a hydrogen circulation system with a hydrogen circulation path, the hydrogen supplied to the anode can be used efficiently. However, nitrogen from the air supplied to the cathode in the fuel cell unit diffuses from the cathode to the anode, causing nitrogen to accumulate in the anode gas of the hydrogen circulation path. As a result, the hydrogen concentration in the gas flowing through the hydrogen circulation path decreases, leading to a decrease in the voltage of the fuel cell and a reduction in the power generation efficiency of the fuel cell.

[0011] Therefore, in Patent Document 1, a purging operation is performed to discharge the anode off-gas to the outside from the hydrogen circulation path at a timely moment when the nitrogen concentration in the anode gas reaches a predetermined value.

[0012] However, Patent Document 1 does not consider controlling the purge valve in consideration of the heat demand of a customer receiving heat from a fuel cell device.

[0013] As a result of diligent study, the Disclosers have found that by controlling the purge valve for discharging anode off-gas from the recycling route, taking into account the heat demand of the customer, it is possible to appropriately control the efficiency of heat recovery generated by the fuel cell device (hereinafter referred to as the heat recovery efficiency of the fuel cell device) in a manner that takes into account the heat demand of the customer, compared to conventional methods, and have come up with the following embodiment of the Disclosure.

[0014] In other words, a control method for a fuel cell system according to a first aspect of the present disclosure is a control method for a fuel cell system including at least one fuel cell unit, which controls a purge valve for discharging anode off-gas from a recycling path for supplying anode off-gas of the fuel cell unit to the anode, based on the ratio of the customer's heat demand to the customer's electricity demand or the customer's heat demand.

[0015] As described above, the control method for the fuel cell device in this embodiment differs from conventional methods in that it can perform appropriate control that takes into account the heat demand of the consumer.

[0016] Generally speaking, there is a trade-off relationship between the power generation efficiency and heat recovery efficiency of a fuel cell system. Therefore, in a hydrogen-recirculating fuel cell system, opening the purge valve lowers the nitrogen concentration in the anode off-gas supplied to the anode, increasing the power generation efficiency of the fuel cell system while decreasing the heat recovery efficiency. Conversely, closing the purge valve increases the nitrogen concentration in the anode off-gas supplied to the anode, decreasing the power generation efficiency of the fuel cell system while increasing the heat recovery efficiency.

[0017] Therefore, the control method for the fuel cell device in this embodiment controls the purge valve while considering the customer's heat demand, which allows the heat generated by the fuel cell device to appropriately meet the customer's heat demand compared to the case where the purge valve is controlled without considering the customer's heat demand.

[0018] A control method for a fuel cell device according to a second aspect of this disclosure may, in the control method for a fuel cell device according to a first aspect, restrict the opening of the purge valve when the ratio of the customer's heat demand to their electricity demand increases.

[0019] As the ratio of heat demand to electricity demand of consumers increases, it is better to prioritize the heat recovery efficiency of the fuel cell system over the power generation efficiency of the fuel cell system. In other words, the control method of the fuel cell system in this embodiment, when the above ratio increases, restricts the opening of the purge valve, thereby increasing the heat recovery efficiency of the fuel cell system compared to when the purge valve is not controlled, and thus the heat generated by the fuel cell system can adequately meet the heat demand of consumers.

[0020] A control method for a fuel cell device according to a third aspect of this disclosure may, in the control method for a fuel cell device according to a first aspect, restrict the opening of the purge valve when the heat demand of the customer increases.

[0021] As the heat demand of consumers increases, it is better to prioritize the heat recovery efficiency of the fuel cell system over the power generation efficiency of the fuel cell system. In other words, the control method of the fuel cell system in this embodiment restricts the opening of the purge valve when the heat demand increases, thereby increasing the heat recovery efficiency of the fuel cell system compared to when the purge valve is not controlled, and thus the heat generated by the fuel cell system can appropriately meet the heat demand of consumers.

[0022] A control method for a fuel cell device according to a fourth aspect of this disclosure may, in a control method for a fuel cell device according to a second aspect, release the restriction on opening the purge valve when the ratio of the customer's heat demand to their electricity demand decreases.

[0023] As the ratio of heat demand to electricity demand of consumers decreases, it is better to prioritize the power generation efficiency of the fuel cell device over the heat recovery efficiency of the fuel cell device. In other words, in the control method of the fuel cell device in this embodiment, when the above ratio decreases, the restriction on opening the purge valve is released, which reduces the heat recovery efficiency of the fuel cell device compared to when the purge valve is not controlled, thus reducing the possibility of an excess of heat supplied by the fuel cell device. Furthermore, in the control method of the fuel cell device in this embodiment, when the above ratio decreases, the restriction on opening the purge valve is released, which increases the power generation efficiency of the fuel cell device compared to when the purge valve is not controlled, so that the electricity generated by the fuel cell device can appropriately meet the electricity demand of consumers.

[0024] A control method for a fuel cell device according to a fifth aspect of this disclosure may, in a control method for a fuel cell device according to a third aspect, release the restriction on opening the purge valve when the customer's heat demand decreases.

[0025] As the heat demand of consumers decreases, it is better to prioritize the power generation efficiency of the fuel cell system over the heat recovery efficiency of the fuel cell system. In other words, the control method for the fuel cell system in this embodiment releases the restriction on opening the purge valve when the heat demand decreases, thereby reducing the heat recovery efficiency of the fuel cell system compared to when the purge valve is not controlled, and thus reducing the possibility of an excess of heat supplied by the fuel cell system. Furthermore, the control method for the fuel cell system in this embodiment releases the restriction on opening the purge valve when the heat demand decreases, thereby increasing the power generation efficiency of the fuel cell system compared to when the purge valve is not controlled, so that the electricity generated by the fuel cell system can appropriately meet the electricity demand of consumers.

[0026] In the control method for a fuel cell device according to the sixth aspect of this disclosure, restricting the opening of the purge valve in the control method for a fuel cell device according to the second or third aspect may mean stopping the opening of the purge valve.

[0027] In the control method for a fuel cell device according to the seventh aspect of this disclosure, restricting the opening of the purge valve in the control method for a fuel cell device according to the second or third aspect may mean reducing the frequency of opening of the purge valve.

[0028] In the control method for a fuel cell device according to the eighth aspect of this disclosure, in the control method for a fuel cell device according to any one of the first to third aspects, the restriction on opening the purge valve may be released after the restriction on opening the purge valve has been initiated and the voltage of the fuel cell device has fallen below a threshold.

[0029] As described above, if the opening of the purge valve is restricted, the amount of nitrogen in the anode gas increases due to nitrogen diffusion from the cathode to the anode, causing the voltage of the fuel cell system to decrease over time.

[0030] In the operation of a fuel cell system, it is generally required that the output voltage of the fuel cell system does not fall below a predetermined lower limit.

[0031] Therefore, the control method for the fuel cell device in this embodiment reduces the possibility of the voltage of the fuel cell device falling below a predetermined lower limit by releasing the restriction on opening the purge valve when the voltage of the fuel cell device falls below a threshold value after the restriction on opening the purge valve has been initiated.

[0032] A control method for a fuel cell device according to the ninth aspect of this disclosure is a control method for a fuel cell device according to any one of the first to third aspects, wherein the fuel cell device includes a plurality of fuel cell units, and the fuel cell units are selected in order of decreasing degradation, and the purge valve of the selected fuel cell unit is controlled.

[0033] It is generally known that as a fuel cell unit deteriorates, its voltage decreases. In other words, the less deteriorated the fuel cell unit is, the higher its voltage is, and therefore the larger the difference between the fuel cell unit's voltage and a predetermined lower limit.

[0034] Therefore, the control method for the fuel cell system in this embodiment controls the purge valves of fuel cell units selected in order of decreasing degradation. Compared to the case where the purge valves of fuel cell units are selected without considering the degree of degradation, the difference between the voltage of the fuel cell unit and a predetermined lower limit tends to be larger, thus ensuring a margin for purge control involving voltage drops in the purge valves of the fuel cell units.

[0035] A tenth aspect of the present disclosure is a control device for a fuel cell system comprising at least one fuel cell unit, comprising: a memory for storing the ratio of the customer's heat demand to the customer's electricity demand or the customer's heat demand; and a controller for controlling a purge valve for discharging anode off-gas from a recycling path for supplying anode off-gas of the fuel cell unit to the anode, based on the ratio of the customer's heat demand to the customer's electricity demand or the customer's heat demand.

[0036] As described above, the control device for the fuel cell system in this embodiment, unlike conventional devices, can perform appropriate control that takes into account the heat demand of the consumer. The details of the effects and benefits of the control device for the fuel cell system in this embodiment are the same as those of the control method for the fuel cell system in the first embodiment, so a detailed explanation is omitted.

[0037] A power generation system according to an eleventh aspect of this disclosure comprises a fuel cell device including at least one fuel cell unit and a control device according to the tenth aspect.

[0038] As described above, the power generation system of this embodiment, unlike conventional systems, can perform appropriate control that takes into account the heat demand of consumers. The details of the effects and benefits of the power generation system of this embodiment are the same as those of the control method for the fuel cell device of the first embodiment, so a detailed explanation is omitted.

[0039] The following describes specific examples of the above embodiments of this disclosure with reference to the attached drawings. The specific examples described below are all examples of the above embodiments of this disclosure. Therefore, the shapes, numerical values, components, arrangement positions of components, and connection configurations shown below do not limit the scope of the claims unless they are described in the claims.

[0040] Furthermore, among the components described below, those not described in the independent claim representing the highest-level concept of this disclosure will be described as optional components. Also, in the drawings, components with the same reference numeral may not be described. The drawings are schematic representations of each component for ease of understanding, and the shape and dimensional ratios may not be accurately represented.

[0041] Furthermore, in the operation of the apparatus, the order of the processes may be changed or known processes may be added as needed.

[0042] (First Embodiment) [Device configuration] Figure 1 shows an example of a power generation system according to the first embodiment. Figure 2 shows an example of the control device of Figure 1.

[0043] As shown in Figure 1, the power generation system 10 of this embodiment comprises a fuel cell device 15 and a control device 20.

[0044] The fuel cell device 15 includes at least one fuel cell unit FC. That is, the fuel cell device 15 may consist of a single fuel cell unit FC as shown in Figure 1, or it may consist of multiple fuel cell units. In the latter case, the power generation system 10 may be, for example, a system that supplies a large amount of power to the power grid. In this case, the power generation system 10 includes a group of fuel cell units consisting of multiple fuel cell units. The detailed configuration of such a power generation system 10 will be described in the second embodiment.

[0045] The fuel cell device 15 generates electricity using an anode gas containing hydrogen and a cathode gas containing oxygen. The anode gas can be hydrogen gas supplied from a hydrogen source. The cathode gas can be air supplied from an air source. The hydrogen source can be, but is not limited to, a hydrogen storage device such as a high-pressure hydrogen tank. The air source can be, but is not limited to, a blower.

[0046] Here, the fuel cell device 15 employs a hydrogen circulation system that includes a recycling path 11 for supplying anode off-gas to the anode 15A, allowing the hydrogen gas supplied to the anode 15A to be used efficiently. However, nitrogen from the air supplied to the cathode 15C in the fuel cell unit FC diffuses from the cathode 15C to the anode 15A, causing nitrogen to accumulate in the recycling path 11. This reduces the hydrogen concentration in the anode gas flowing through the recycling path 11, thereby decreasing the power generation efficiency of the fuel cell device 15. Therefore, to suppress the decrease in power generation efficiency of the fuel cell device 15, a purging operation is generally performed at an appropriate time to discharge the anode off-gas from the recycling path 11 to the outside. Specifically, the anode off-gas of the fuel cell unit FC is discharged from the recycling path 11 by controlling the opening and closing of the purge valve 12. The purge valve 12 can be any type as long as it is configured to discharge the anode off-gas from the recycling path 11 to the outside by valve operation. For example, a solenoid valve can be used as the purge valve 12, but it is not limited to this.

[0047] The fuel cell device 15 has an optimal operating temperature range. Therefore, the heat transfer medium circulates through the fuel cell stack contained in the fuel cell device 15. This allows the heat transfer medium to recover waste heat from the fuel cell device 15, maintaining the operating temperature of the fuel cell device 15 at an optimal temperature, and the waste heat recovered by the heat transfer medium is stored in a heat accumulator. Examples of heat accumulators include, but are not limited to, a hot water storage tank that stores water, which is an example of a heat transfer medium. In addition, a discharger (e.g., a pump) and a heat exchanger are provided in the flow path through which the heat transfer medium flows.

[0048] As shown in Figure 2, the control device 20 comprises a memory 21 and a controller 23. The control device 20 may consist of a single controller that performs centralized control, or it may consist of multiple controllers that cooperate with each other to perform distributed control. In this embodiment, the control device 20 is described as a control device for a single fuel cell unit FC, but if the fuel cell system 15 comprises multiple fuel cell units FC, it may be a control device that cooperates with the control devices of each fuel cell unit FC to control multiple fuel cell units, or it may be a control device integrated with the control devices of each fuel cell unit FC.

[0049] The memory device 21 is a device that stores the ratio of the customer's heat demand to their power demand, or the customer's heat demand. For example, memory can be used as the memory device 21. Alternatively, the control device 20 may receive information such as the customer's power demand and heat demand from an external source at predetermined intervals via a communication network and store it in the memory device 21.

[0050] Here, "consumer" refers to a user who receives electricity and heat from the power generation system 10. If the electricity and heat supply services from the power generation system 10 are provided, for example, to a facility within a factory or store, "consumer" may also refer to the manager of that facility.

[0051] The controller 23 controls the purge valve 12 for discharging anode off-gas from the recycling path 11 for supplying anode off-gas from the fuel cell unit FC to the anode 15A, based on the ratio of the customer's heat demand to electricity demand or the customer's heat demand.

[0052] The controller 23 can be any device that has a control function and comprises an arithmetic processing unit and a storage unit. For example, a microprocessor is an example of the arithmetic processing unit. For example, memory is an example of the storage unit.

[0053] [Operation] Figures 3A and 3B are flowcharts illustrating an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the first embodiment. The following operations may be performed, for example, by the arithmetic processing unit of the controller 23 of the control device 20 reading a control program from the memory 21 of the control device 20. However, it is not necessarily required that the controller 23 perform the following operations. The operator may perform some of these operations. The following example describes the case in which the operation is controlled by the controller 23.

[0054] As shown in Figure 3A, during power generation by the power generation system 10, at predetermined intervals, in step S1A, the power demand PD and heat demand HD of consumers receiving power and heat from the power generation system 10 are acquired. The "determined time" may be approximately 30 seconds, but is not limited to this.

[0055] Next, in step S2A, the purge valve 12 is controlled based on the ratio R (=HD / PD) of the customer's heat demand HD to their power demand PD. The details of the control of the purge valve 12 in step S2A will be explained in the embodiment.

[0056] As shown in Figure 3B, during power generation by the power generation system 10, at predetermined intervals, in step S1B, the heat demand HD of the consumer receiving heat from the power generation system 10 is acquired. The "predetermined interval" may be approximately 30 seconds, but is not limited to this.

[0057] Next, in step S2B, the purge valve 12 is controlled based on the customer's heat demand HD. The details of the control of the purge valve 12 in step S2B will be explained in the embodiment.

[0058] According to the embodiment described above, unlike conventional methods, it is possible to perform appropriate control that takes into account the heat demand HD of the consumer.

[0059] Generally, there is a trade-off relationship between the power generation efficiency and heat recovery efficiency of the fuel cell device 15. Therefore, in a hydrogen-recycling fuel cell device 15, opening the purge valve 12 lowers the nitrogen concentration in the anode off-gas supplied to the anode 15A, thus increasing the power generation efficiency of the fuel cell device 15 and decreasing its heat recovery efficiency. Conversely, closing the purge valve 12 increases the nitrogen concentration in the anode off-gas supplied to the anode 15A, thus decreasing the power generation efficiency of the fuel cell device 15 and increasing its heat recovery efficiency.

[0060] Therefore, according to this embodiment, by controlling the purge valve 12 in consideration of the customer's heat demand HD, the heat generated by the fuel cell device 15 can appropriately meet the customer's heat demand HD, compared to when the purge valve 12 is controlled without considering the customer's heat demand HD.

[0061] (First embodiment) The control method for the fuel cell device 15 of the first embodiment is the same as the control method for the fuel cell device 15 of the first embodiment, except for the control contents of the controller 23 described below.

[0062] Figure 4A is a flowchart showing an example of the operation of the control device (control method for the fuel cell device) in the power generation system of the first embodiment of the first embodiment. The following operations may be performed, for example, by the arithmetic processing unit of the controller 23 of the control device 20 reading a control program from the memory 21 of the control device 20. However, it is not necessarily required that the controller 23 perform the following operations. The operator may perform some of the operations. In the following example, the case in which the operation is controlled by the controller 23 will be described. Note that step S1A in Figure 4A is the same as step S1A in Figure 3A, so the explanation will be omitted.

[0063] In step S2A-1, it is determined whether the ratio R of the customer's heat demand HD to their power demand PD has increased. This determination may be made by comparing it with a predetermined threshold.

[0064] If it is determined that the ratio R of the customer's heat demand HD to their power demand PD has increased (if the answer is "Yes" in step S2A-1), then in step S2A-2, the opening of the purge valve 12 is restricted.

[0065] Here, "restricting the opening of the purge valve 12" may mean stopping the opening of the purge valve 12 or reducing the frequency of the opening of the purge valve 12.

[0066] Specifically, as shown in Figure 6A, the voltage-time change 203 (dotted line) of the fuel cell device 15 corresponding to the opening and closing of the purge valve 12 of the fuel cell device 15 is lower than the voltage-time change 202 of the fuel cell device 15 corresponding to the operation of the purge valve 12 in which the opening and closing of the purge valve 12 for discharging anode off gas to the outside from the recycling path 11 is repeated at regular intervals (hereinafter referred to as the opening and closing operation of the purge valve 12 in the comparative example), and the voltage-time change 201 of the fuel cell device corresponding to the case where a hydrogen circulation method is not adopted. Note that the "voltage of the fuel cell device 15" in Figure 6A is the value received by the control device 20 at the voltage stabilization timing when the fuel cell device 15 is generating power at its rated output. The "voltage stabilization timing" is, for example, the timing in the period of time when the voltage stabilizes after a predetermined time has elapsed since the start of power generation by the fuel cell device 15. Therefore, the voltage measured by the voltmeter during power generation by the fuel cell device 15 may be the average value of the voltage during that period.

[0067] As shown in Figure 6B, the voltage-time change 204 (dotted line) of the fuel cell device 15 corresponding to the decrease in the opening frequency of the purge valve 12 of the fuel cell device 15 is lower than the voltage-time change 202 of the fuel cell device 15 corresponding to the opening and closing operation of the purge valve 12 in the comparative example, and the voltage-time change 201 of the fuel cell device 15 corresponding to the case where a hydrogen circulation method is not adopted. The "voltage of the fuel cell device 15" in Figure 6B is the same as above, so the explanation is omitted.

[0068] In the example shown in Figure 6B, during the voltage-time change 204 of the fuel cell device 15, the opening time of the purge valve 12 is set to "T1", and the closing time of the purge valve 12 is set to "T2", which is longer than "T1". In contrast, during the voltage-time change 202 of the fuel cell device 15, both the closing time and opening time of the purge valve 12 are set to "T1".

[0069] If it is determined that the ratio R of the customer's heat demand HD to their power demand PD does not increase (i.e., "No" in step S2A-1), the operation in step S1A is re-executed after a predetermined time has elapsed. The "predetermined time" may be approximately 30 seconds, but is not limited to this.

[0070] In the operation of the purge valve 12 in step S2A-2 of this embodiment, the nitrogen concentration in the anode off-gas supplied to the anode 15A increases compared to the case where the purge valve 12 is opened and closed in the comparative example. As a result, the power generation efficiency of the fuel cell device 15 decreases, while the heat recovery efficiency of the fuel cell device 15 increases.

[0071] As the ratio R of the customer's heat demand HD to their electricity demand PD increases, it is better to prioritize the heat recovery efficiency of the fuel cell device 15 over the power generation efficiency of the fuel cell device 15. In other words, the control method of the fuel cell device 15 in this embodiment restricts the opening of the purge valve 12 as the ratio R increases, thereby increasing the heat recovery efficiency of the fuel cell device 15 compared to the case where the purge valve 12 is not controlled. As a result, the heat generated by the fuel cell device 15 can appropriately meet the customer's heat demand HD.

[0072] The above operations are illustrative and not limited to this example. In the voltage-time change 202 of the fuel cell device 15 in Figure 6A, the opening and closing of the purge valve 12 does not necessarily have to be repeated at regular intervals. Also, in the voltage-time change 204 of the fuel cell device 15 in Figure 6B, the closing and opening times of the purge valve 12 are arbitrary, as long as the opening and closing of the purge valve 12 is controlled so that the frequency of opening the purge valve 12 is reduced compared to the case of the voltage-time change 202 of the fuel cell device 15.

[0073] The control method, control device 20, and power generation system 10 of the fuel cell device 15 in this embodiment may be the same as those of the first embodiment, except for the features described above.

[0074] (Second example) The control method for the fuel cell device 15 in the second embodiment of the first embodiment is the same as the control method for the fuel cell device 15 in the first embodiment, except for the control contents of the controller 23 described below.

[0075] Figure 4B is a flowchart showing an example of the operation of a control device (control method for a fuel cell device) in a power generation system according to the second embodiment of the first embodiment. The following operations may be performed, for example, by the arithmetic processing unit of the controller 23 of the control device 20 reading a control program from the memory 21 of the control device 20. However, it is not necessarily required that the controller 23 perform the following operations. The operator may perform some of these operations. In the following example, the case in which the operation is controlled by the controller 23 will be described. Note that step S1B in Figure 4B is the same as step S1B in Figure 3B, so the explanation will be omitted.

[0076] In step S2B-1, it is determined whether the customer's heat demand HD has increased. This determination may be made by comparing it with a predetermined threshold.

[0077] If it is determined that the customer's heat demand HD has increased (if the answer is "Yes" in step S2B-1), the opening of the purge valve 12 is restricted in step S2B-2.

[0078] Here, "restricting the opening of the purge valve 12" may mean stopping the opening of the purge valve 12 or reducing the frequency of the opening of the purge valve 12. Details of the operation to restrict the opening of the purge valve 12 are the same as described above, so an explanation is omitted.

[0079] If it is determined that the customer's heat demand HD will not increase (i.e., "No" in step S2B-1), the operation in step S1B is re-executed after a predetermined time has elapsed. The "predetermined time" may be approximately 30 seconds, but is not limited to this.

[0080] In the operation of the purge valve 12 in step S2B-2 of this embodiment, the nitrogen concentration in the anode off-gas supplied to the anode 15A increases compared to the case where the purge valve 12 is opened and closed in the comparative example. As a result, the power generation efficiency of the fuel cell device 15 decreases, while the heat recovery efficiency of the fuel cell device 15 increases.

[0081] As the customer's heat demand HD increases, it is better to prioritize the heat recovery efficiency of the fuel cell device 15 over the power generation efficiency of the fuel cell device 15. In other words, the control method of the fuel cell device 15 in this embodiment restricts the opening of the purge valve 12 when the heat demand HD increases, thereby increasing the heat recovery efficiency of the fuel cell device 15 compared to when the purge valve 12 is not controlled. As a result, the heat generated by the fuel cell device 15 can appropriately meet the customer's heat demand HD.

[0082] The control method, control device 20, and power generation system 10 of the fuel cell device 15 in this embodiment may be the same as those of the first embodiment or the first embodiment of the first embodiment, except for the features described above.

[0083] (Third embodiment) The control method for the fuel cell device 15 in the third embodiment of the first embodiment is the same as the control method for the fuel cell device 15 in the first embodiment of the first embodiment, except for the control contents of the controller 23 described below.

[0084] Figure 5A is a flowchart showing an example of the operation of a control device (control method for a fuel cell device) in a power generation system according to the third embodiment of the first embodiment. The following operations may be performed, for example, by the arithmetic processing unit of the controller 23 of the control device 20 reading a control program from the memory 21 of the control device 20. However, it is not necessarily required that the controller 23 perform the following operations. The operator may perform some of these operations. In the following example, the case in which the operation is controlled by the controller 23 will be described. Note that step S1A in Figure 5A is the same as step S1A in Figure 3A, so the explanation will be omitted.

[0085] In step S2A-2 of Figure 4A, after restricting the opening of the purge valve 12, in step S2A-3, it is determined whether the ratio R of the heat demand HD to the power demand PD of the customer has decreased. This determination may also be made by comparing it with a predetermined threshold.

[0086] If it is determined that the ratio R of the customer's heat demand HD to their power demand PD has decreased (if the answer is "Yes" in step S2A-3), the restriction on opening the purge valve 12 is released in step S2A-4.

[0087] The operation of restricting the opening of the purge valve 12 is the same as described above, so the explanation is omitted.

[0088] "Removing the restriction on opening the purge valve 12" means restoring the opening and closing operation of the purge valve 12 to the operation it was in before its opening was restricted. In the example shown in Figure 6A, one example of "removing the restriction on opening the purge valve 12" is to transition from the operation of the purge valve 12 corresponding to the voltage-time change 203 (dotted line) of the fuel cell device 15 to the operation of the purge valve 12 corresponding to the voltage-time change 202 of the fuel cell device 15.

[0089] If it is determined that the ratio R of the customer's heat demand HD to their power demand PD does not decrease (i.e., "No" in step S2A-3), the operation in step S1A is re-executed after a predetermined time has elapsed. The "predetermined time" may be approximately 30 seconds, but is not limited to this.

[0090] In this embodiment, the operation of the purge valve 12 in step S2A-4 results in a decrease in the nitrogen concentration in the anode off-gas supplied to the anode 15A compared to when the opening of the purge valve 12 is restricted. As a result, the power generation efficiency of the fuel cell device 15 increases, while the heat recovery efficiency of the fuel cell device 15 decreases.

[0091] As the ratio R of heat demand HD to electricity demand PD of the customer decreases, it is better to prioritize the power generation efficiency of the fuel cell device 15 over the heat recovery efficiency of the fuel cell device 15. In other words, in the control method of the fuel cell device 15 in this embodiment, when the ratio R decreases, the restriction on opening the purge valve 12 is released, which reduces the heat recovery efficiency of the fuel cell device 15 compared to when the purge valve 12 is not controlled, thus reducing the possibility of an excess of heat supplied by the fuel cell device 15. Also, in the control method of the fuel cell device 15 in this embodiment, when the ratio R decreases, the restriction on opening the purge valve 12 is released, which increases the power generation efficiency of the fuel cell device 15 compared to when the purge valve 12 is not controlled, so that the electricity generated by the fuel cell device 15 can appropriately meet the customer's electricity demand PD.

[0092] The control method, control device 20, and power generation system 10 of the fuel cell device 15 in this embodiment may be the same as those of the first embodiment or the first embodiment of the first embodiment, except for the features described above.

[0093] (Fourth embodiment) The control method for the fuel cell device 15 in the fourth embodiment of the first embodiment is the same as the control method for the fuel cell device 15 in the first embodiment of the first embodiment, except for the control contents of the controller 23 described below.

[0094] Figure 5B is a flowchart showing an example of the operation of a control device (control method for a fuel cell device) in a power generation system according to the fourth embodiment of the first embodiment. The following operations may be performed, for example, by the arithmetic processing unit of the controller 23 of the control device 20 reading a control program from the memory 21 of the control device 20. However, it is not necessarily required that the controller 23 perform the following operations. The operator may perform some of the operations. In the following example, the case in which the operation is controlled by the controller 23 will be described. Note that step S1B in Figure 5B is the same as step S1B in Figure 3B, so the explanation will be omitted.

[0095] In step S2B-2 of Figure 4B, after restricting the opening of the purge valve 12, in step S2B-3, it is determined whether or not the customer's heat demand HD has decreased. This determination may also be made by comparing it with a predetermined threshold.

[0096] If it is determined that the customer's heat demand HD has decreased (if the answer is "Yes" in step S2B-3), the restriction on opening the purge valve 12 is released in step S2B-4.

[0097] The operation of restricting the opening of the purge valve 12 is the same as described above, so the explanation is omitted.

[0098] "Removing the restriction on opening the purge valve 12" means restoring the opening and closing operation of the purge valve 12 to the operation it was in before its opening was restricted. In the example shown in Figure 6A, one example of "removing the restriction on opening the purge valve 12" is to transition from the operation of the purge valve 12 corresponding to the voltage-time change 203 (dotted line) of the fuel cell device 15 to the operation of the purge valve 12 corresponding to the voltage-time change 202 of the fuel cell device 15.

[0099] If it is determined that the ratio R of the customer's heat demand HD does not decrease (i.e., "No" in step S2A-3), the operation in step S1B is re-executed after a predetermined time has elapsed. The "predetermined time" may be approximately 30 seconds, but is not limited to this.

[0100] In this embodiment, the operation of the purge valve 12 in step S2B-4 results in a decrease in nitrogen concentration in the anode off-gas supplied to the anode 15A compared to when the opening of the purge valve 12 is restricted. As a result, the power generation efficiency of the fuel cell device 15 increases, while the heat recovery efficiency of the fuel cell device 15 decreases.

[0101] As the customer's heat demand HD decreases, it is better to prioritize the power generation efficiency of the fuel cell device 15 over the heat recovery efficiency of the fuel cell device 15. In other words, the control method of the fuel cell device 15 in this embodiment releases the restriction on opening the purge valve 12 when the heat demand HD decreases, thereby reducing the heat recovery efficiency of the fuel cell device 15 compared to when the purge valve 12 is not controlled, and thus reducing the possibility of an excess of heat supplied by the fuel cell device 15. Furthermore, the control method of the fuel cell device 15 in this embodiment releases the restriction on opening the purge valve 12 when the heat demand HD decreases, thereby increasing the power generation efficiency of the fuel cell device 15 compared to when the purge valve 12 is not controlled, so that the electricity generated by the fuel cell device 15 can appropriately meet the customer's electricity demand PD.

[0102] The control method, control device 20, and power generation system 10 of the fuel cell device 15 in this embodiment may be the same as those of the first embodiment or the third embodiment of the first embodiment, except for the features described above.

[0103] (Fifth example) The control method for the fuel cell device 15 of the fifth embodiment of the first embodiment is the same as the control method for the fuel cell device 15 of the first embodiment of the first embodiment, except for the control contents of the controller 23 described below.

[0104] In the control method for the fuel cell device 15 of this embodiment, after the restriction on opening the purge valve 12 is initiated, the restriction is released when the voltage of the fuel cell device 15 falls below a threshold. "Release of the restriction on opening the purge valve 12" means opening the purge valve 12 according to predetermined conditions. Details of the operation of the purge valve 12 will be described in the second embodiment.

[0105] As described above, if the opening of the purge valve 12 is restricted, the amount of nitrogen in the anode gas increases due to nitrogen diffusion from the cathode 15C to the anode 15A, causing the voltage of the fuel cell device 15 to decrease over time.

[0106] In general, during the operation of the fuel cell device 15, it is required that the output voltage of the fuel cell device 15 does not fall below a predetermined lower limit.

[0107] Therefore, the control method for the fuel cell device 15 in this embodiment reduces the possibility of the voltage of the fuel cell device 15 falling below a predetermined lower limit by releasing the restriction on opening the purge valve 12 when the voltage of the fuel cell device 15 falls below a threshold value after the restriction on opening the purge valve 12 has been initiated.

[0108] The control method, control device 20, and power generation system 10 of the fuel cell device 15 in this embodiment may be the same as those of the first embodiment and any of the first to fourth embodiments of the first embodiment, except for the features described above.

[0109] (Second Embodiment) [Device configuration] Figure 7 shows an example of a power generation system according to the second embodiment. In Figure 7, a power consumer 30 and a heat consumer 40 are shown together with the power generation system 10. Examples of power consumer 30 include various electrical equipment managed by a consumer in a factory or store. Examples of heat consumer 40 include various heating equipment managed by a consumer in a factory or store.

[0110] The power generation system 10 of this embodiment comprises a fuel cell device 15 and a control device 20, as shown in Figure 7. Here, the configuration of the control device 20 is the same as in the first embodiment, so a detailed explanation is omitted.

[0111] In the example shown in Figure 7, the fuel cell device 15 consists of multiple fuel cell units FC1~FC n It is equipped with the following. Although not shown in the illustration, these fuel cell units FC1~FC n Each of these components consists of a fuel cell stack, an orthogonal converter for converting the DC power generated by the fuel cell stack into AC power and outputting it to the power grid, and a control device for controlling the operation of these devices. The control device 20 is connected to fuel cell units FC1~FC nIntegrated with each control device therein, in other words, equipped with the control functions of such control devices, directly controlling the operations of each device of the fuel cell units FC1 to FC n It may also control the operations of each device of the fuel cell units FC1 to FC n In cooperation with each control device within the fuel cell units FC1 to FC n It may control the operations of each device of the fuel cell units FC1 to FC

[0112] For example, the controller 23 of the control device 20 may control all the purge valves 12 of the fuel cell units FC1 to FC n as described above, but the control devices within the fuel cell units FC1 to FC n may each control their respective purge valves 12 of each fuel cell unit FC1 to FC n as described above. Also, the controller 23 of the control device 20 may control the outputs of these fuel cell units FC1 to FC n so as to enable efficient operation (e.g., optimization of lifespan). n

[0113] Also, for example, the controller 23 of the control device 20 may select the fuel cell units FC1 to FC n in ascending order of low degradation degree among the fuel cell units FC1 to FC n At this time, the controller 23 of the control device 20 may control all the purge valves 12 of the selected fuel cell units FC1 to FC n as described above, but the control devices within the selected fuel cell units FC1 to FC n may each control their respective purge valves 12 of each fuel cell unit FC1 to FC n as described above.

[0114] Here, it is generally known that as the degradation of each individual fuel cell unit FC1 to FC n progresses, a voltage drop occurs in the fuel cell units FC1 to FC n Therefore, the fuel cell units FC1 to FC​n The lower the degree of degradation, the better the fuel cell unit FC1~FC n The voltage is high. Therefore, fuel cell unit FC1~FC n During rated operation, at the voltage stabilization timing when a predetermined time has elapsed from the start of power generation and the voltage stabilizes, fuel cell units FC1~FC n By measuring the voltage of the "Fuel Cell Unit FC1~FC n This allows you to know the "degree of degradation". Note that fuel cell units FC1~FC n The degradation progresses, for example, with an increase in cumulative power generation time.

[0115] [Operation] <Fuel cell unit FC1~FC n Select operating mode > Figures 8A and 8B are flowcharts illustrating an example of the operation of a control device (control method for a fuel cell device) in a power generation system of the second embodiment. The following operations may be performed, for example, by the arithmetic processing unit of the controller 23 of the control device 20 reading a control program from the memory 21 of the control device 20. However, it is not necessarily required that the controller 23 perform the following operations. An operator may perform some of these operations. The following example describes the case in which the operation is controlled by the controller 23.

[0116] In the example shown in Figure 8A, step S10 determines whether or not predetermined conditions regarding the customer's heat demand HD are met. Whether or not "predetermined conditions are met" may be determined by whether or not the ratio R (=PD / HD) of the customer's heat demand HD to the customer's power demand PD has increased, as described above, or by whether or not the customer's heat demand HD has increased. This determination may also be made by comparing with a predetermined threshold.

[0117] If, in step S10, it is determined that the customer's heat demand HD meets the predetermined conditions (if the answer is "Yes" in step S10), then in step S11, all fuel cell units FC1~FC that are generating power are checked. nIn response, the purge valve 12 is instructed to operate in "heat dissipation boost mode." A specific example of purge valve control in this "heat dissipation boost mode" will be explained later.

[0118] If, in step S10, it is determined that the customer's heat demand HD does not meet the predetermined conditions (if the answer is "No" in step S10), then in step S12, all fuel cell units FC1~FC that are generating power are checked. n In response, "normal mode" is instructed as the operating mode for the purge valve 12. This "normal mode" may, for example, be the mode in which the opening and closing operation of the comparative example of the purge valve 12 is performed.

[0119] Next, the fuel cell units FC1~FC shown in Figure 8B n The selection of the operating mode will be explained. Note that step S10 in Figure 8B is the same as step S10 in Figure 8A, so the explanation will be omitted.

[0120] If, in step S10, it is determined that the heat demand HD of the customer meets the predetermined conditions (if the answer is "Yes" in step S10), then in step S111, the number of fuel cell units M for the waste heat up mode is calculated using the following formula (1).

[0121] M = Increase in heat required for the fuel cell device / Increase in waste heat per fuel cell unit... (1) In equation (1), the "increase in heat required for the fuel cell system" is calculated using the fuel cell units FC1~FC during power generation. n This can be determined from the amount of waste heat (measured data) and the heat demand (HD) of the consumer. The "amount of waste heat increase per fuel cell unit" is the amount of waste heat increase expected per fuel cell unit by executing the waste heat increase mode, and can be determined from appropriate preliminary experiments or numerical simulations.

[0122] Next, in step S112, the number of fuel cell units M from step S111 are ordered in descending order of degradation level, from the fuel cell units FC1 to FC1 that are currently generating power. n The selected one.

[0123] Next, in step S113, the fuel cell units FC1 to FC selected in step S112 are selected. n In response, the purge valve 12 is instructed to operate in "heat dissipation boost mode." A specific example of purge valve control in this "heat dissipation boost mode" will be explained later.

[0124] Next, in step S114, the fuel cell units FC1~FC that were not selected in step S112 are selected. n In response, "normal mode" is instructed as the operating mode for the purge valve 12. This "normal mode" may, for example, be the mode in which the opening and closing operation of the comparative example of the purge valve 12 is performed.

[0125] If, in step S10, it is determined that the customer's heat demand HD does not meet the predetermined conditions (if the answer is "No" in step S10), then in step S12, all fuel cell units FC1~FC that are generating power are checked. n In response, "normal mode" is instructed as the operating mode for the purge valve 12. This "normal mode" may, for example, be the mode in which the opening and closing operation of the comparative example of the purge valve 12 is performed.

[0126] Fuel cell unit FC1~FC n Generally, as degradation progresses, the fuel cell unit FC1~FC n It is known that the voltage of the fuel cell unit FC1~FC decreases. n The lower the degree of degradation, the better the fuel cell unit FC1~FC n Because the voltage is high, fuel cell unit FC1~FC n The difference between the voltage and the predetermined lower limit is large.

[0127] Therefore, according to the embodiment described above, fuel cell units FC1 to FC are selected in order of decreasing degradation. n By controlling the purge valve 12, the fuel cell units FC1~FC selected without considering the degree of degradation can be controlled. nCompared to controlling the purge valve 12 of the fuel cell unit FC1~FC n Because the difference between the voltage and the predetermined lower limit tends to be large, fuel cell unit FC1~FC n This makes it easier to ensure a margin of safety in the purge control of the purge valve 12, even when there is a voltage drop.

[0128] <Specific example of purge valve control in heat dissipation mode> Figures 9A and 9B are flowcharts illustrating an example of the operation of the control device (control method for the fuel cell device) in the waste heat up mode of the power generation system of the second embodiment. The following operation applies, for example, to fuel cell units FC1~FC n The control program may be performed by the arithmetic processing unit of the control device reading the control program from the memory unit of the control device, but is not limited to this. For example, the following operations may be performed by the arithmetic processing unit of the controller 23 of the control device 20 reading the control program from the memory unit 21 of the control device 20. Alternatively, the operator may perform some of the following operations. In the following example, fuel cell units FC1~FC n This section describes how the operation is controlled by an internal control device.

[0129] In the example shown in Figure 9A, in step S20A, fuel cell units FC1~FC are instructed to enter the exhaust heat up mode. n The purge valve 12 is closed. When the purge valve 12 is closed, the fuel cell units FC1~FC in Figure 10A are closed. n As shown by the voltage-time change 203 (dotted line), the amount of nitrogen in the anode gas increases due to nitrogen diffusion from the cathode 15C to the anode 15A, causing the voltage of the fuel cell device 15 to decrease monotonically over time.

[0130] Therefore, in step S21, it is determined whether the voltage of the fuel cell device 15 falls below threshold A. In general, during the operation of the fuel cell device 15, it is required that the output voltage of the fuel cell device 15 does not fall below a predetermined lower limit, so "threshold A" in Figure 10A is set based on that predetermined lower limit.

[0131] If the voltage of the fuel cell device 15 exceeds threshold A (if the answer is "No" in step S21), the state of the purge valve 12, which was closed in step S20A, is maintained.

[0132] When the voltage of the fuel cell device 15 falls below threshold A (if "Yes" is answered in step S21), the process proceeds to the next step S22, in which the purge valve 12, which was closed in step S20A, is opened. When the purge valve 12 is opened, the fuel cell units FC1~FC in Figure 10A are opened. n As shown by the voltage-time change 203 (dotted line), the amount of nitrogen in the anode gas decreases, causing the voltage of the fuel cell device 15 to rise monotonically over time.

[0133] Therefore, in step S23, it is determined whether or not predetermined conditions are met regarding the voltage of the fuel cell device 15. Here, the determination of whether or not the "predetermined conditions" are met is made as shown in Figure 10A, with fuel cell units FC1~FC n This may be done by comparing the voltage with a threshold B that is greater than threshold A, or by checking whether a predetermined time T3 has elapsed since the opening timing of the purge valve 12.

[0134] If it is determined that the "predetermined conditions" are not met (i.e., "No" in step S23), the state of the purge valve 12 that was opened in step S22 is maintained.

[0135] If it is determined that the "predetermined conditions" are met (i.e., "Yes" in step S23), the operations from step S20A onward are re-executed.

[0136] In the example shown in Figure 9B, in step S20B, fuel cell units FC1~FC are instructed to enter the heat dissipation mode. n The frequency of opening the purge valve 12 is reduced compared to when the opening and closing operation of the comparative example of the purge valve 12 is performed. When the frequency of opening the purge valve 12 is reduced in this way, the fuel cell units FC1~FC in Figure 10B nAs shown by the voltage-time change 204 (dotted line), the amount of nitrogen in the anode gas increases due to nitrogen diffusion from the cathode 15C to the anode 15A, so the voltage of the fuel cell device 15 repeatedly increases and decreases, and the voltage decreases over time.

[0137] Therefore, in step S21, it is determined whether the voltage of the fuel cell device 15 is below threshold A. Note that "threshold A" is the same as described above, so a detailed explanation is omitted.

[0138] If the voltage of the fuel cell device 15 exceeds threshold A (if the answer is "No" in step S21), the state of the purge valve 12, whose opening frequency was reduced in step S20B, is maintained.

[0139] When the voltage of the fuel cell device 15 falls below threshold A (if "Yes" is answered in step S21), the process proceeds to the next step S22, in which the purge valve 12, whose opening frequency was reduced in step S20B, is opened. When the purge valve 12 is opened, the fuel cell units FC1~FC in Figure 10B are opened. n As shown by the voltage-time variation 204 (dotted line), the amount of nitrogen in the anode gas decreases, causing the voltage of the fuel cell device 15 to rise monotonically over time.

[0140] Therefore, in step S23, it is determined whether the voltage of the fuel cell device 15 satisfies predetermined conditions. Since the "predetermined conditions" are the same as described above, a detailed explanation is omitted.

[0141] If it is determined that the "predetermined conditions" are not met (i.e., "No" in step S23), the state of the purge valve 12 that was opened in step S22 is maintained.

[0142] If it is determined that the "predetermined conditions" are met (i.e., "Yes" in step S23), the operations from step S20B onward are re-executed.

[0143] The control method, control device 20, and power generation system 10 of the fuel cell device 15 of this embodiment may be the same as those of the first embodiment and any of the first to fifth embodiments of the first embodiment, except for the features described above.

[0144] The first embodiment, the first-fifth embodiments of the first embodiment, and the second embodiment may be combined with each other, provided that they do not exclude one another. From the above description, many improvements and other embodiments of the disclosure will be apparent to those skilled in the art. Therefore, the above description should be interpreted as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the disclosure. The details of its structure and / or function may be substantially modified without departing from the spirit of the disclosure. [Industrial applicability]

[0145] One aspect of this disclosure can be used in a control method, control device, and power generation system for a fuel cell device that, unlike conventional methods, can perform appropriate control that takes into account the heat demand of consumers. [Explanation of Symbols]

[0146] 10: Power generation system 11: Recycling Route 12: Purge valve 15:Fuel cell device 15A: Anode 15C: Cathode 20: Control device 21: Memory device 23: Controller 30:Electricity demand body 40:Heat demand body 201: Voltage-Time Variation 202: Voltage-Time Variation 203: Voltage-Time Variation 204: Voltage-Time Variation FC: Fuel cell unit

Claims

1. A control method for a fuel cell system including at least one fuel cell unit, A control method for controlling a purge valve for discharging anode off-gas from a recycling path for supplying anode off-gas of a fuel cell unit to the anode, based on the ratio of the customer's heat demand to electricity demand or the customer's heat demand.

2. The control method according to claim 1, wherein the opening of the purge valve is restricted when the ratio increases.

3. The control method according to claim 1, wherein the opening of the purge valve is restricted when the heat demand of the customer increases.

4. The control method according to claim 2, wherein the opening of the purge valve is restricted, and then the restriction is released when the ratio decreases.

5. The control method according to claim 3, wherein the opening of the purge valve is restricted, and then the restriction is released when the heat demand decreases.

6. The control method according to claim 2 or 3, wherein restricting the opening of the purge valve means stopping the opening of the purge valve.

7. The control method according to claim 2 or 3, wherein restricting the opening of the purge valve means reducing the frequency of opening the purge valve.

8. The control method according to any one of claims l-3, wherein after the restriction is initiated, the restriction is released when the voltage of the fuel cell device falls below a threshold.

9. The fuel cell device includes a plurality of fuel cell units, A control method according to any one of claims 1 to 3, comprising selecting fuel cell units in order of decreasing degree of deterioration, and controlling the purge valve corresponding to the selected fuel cell unit based on the ratio of the customer's heat demand to the customer's electricity demand or the customer's heat demand.

10. A control device for a fuel cell system comprising at least one fuel cell unit, A memory device that stores the ratio of a customer's heat demand to their electricity demand, or the heat demand of the customer. A control device comprising: a controller for controlling a purge valve for discharging anode off-gas from a recycling path for supplying anode off-gas of the fuel cell unit to the anode, based on the ratio of the customer's heat demand to electricity demand or the customer's heat demand.

11. A fuel cell system including at least one fuel cell unit, A power generation system comprising the control device described in claim 10.

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