JP2017135036A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system that performs temperature measurement control that satisfies temperature accuracy and response speeds different for each portion and each operation stage of a fuel cell device.SOLUTION: A fuel cell system 1 comprises: a fuel cell device 1a that comprises a cell stack 5 for generating power by a fuel gas and an oxygen-containing gas; and temperature measurement parts installed at a plurality of portions that are preliminarily defined in the fuel cell device 1a, and that measure temperatures at the installation portions. The controller 2 determines whether or not supply of power to an external load 3 is executed, and in a case where the supply of power to the external load 3 is executed, sequentially makes the plurality of temperature measurement parts measure the temperature in a first cycle that is preliminarily defined, and in a case where the supply of power to the external load is not executed, sequentially makes the plurality of temperature measurement parts measure the temperature in a second cycle that is preliminarily defined and different from the first cycle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system that includes a fuel cell device that generates electric power using a fuel gas and an oxygen-containing gas, and controls the fuel cell device to supply electric power to an external load.

  In recent years, a cell stack device in which a plurality of fuel cells that can obtain electric power using hydrogen-containing gas (or fuel gas) and oxygen-containing gas (air) is arranged as next-generation energy has been known. Various fuel cell modules in which a cell stack device is housed in a housing container, and fuel cell devices in which a fuel cell module and various auxiliary machines are housed in an outer case have been proposed. In addition, a fuel cell device having a configuration in which combustion gas that has not been used for power generation is burned and the temperature of the fuel cell or the like is maintained at a high temperature by the combustion heat has been proposed (for example, see Patent Document 1).

  In such various fuel cell devices, in order to manage the operation state, a temperature measuring unit for measuring the temperature of each unit is provided, and various controls are performed based on the temperatures measured by these temperature measuring units. Is done.

Japanese Patent Laying-Open No. 2015-185289

  By the way, in the fuel cell system, various controls are performed based on the temperature of the temperature measurement unit described above. When a plurality of temperature measurement units are provided, the measurement time and the measurement related to the temperature measurement of each temperature measurement unit are performed. Depending on the cycle, temperature information could not be obtained in a timely manner, and there was a risk that appropriate control could not be performed, such as a delay in response speed. Further, when the measurement time or measurement cycle of the temperature measurement unit is advanced, there is a possibility that accurate temperature information cannot be obtained due to the influence of noise from other devices.

A fuel cell system according to an embodiment of the present invention includes a fuel cell device including a fuel cell that generates power using fuel gas and oxygen-containing gas;
A temperature measuring unit that is installed at a plurality of predetermined sites in the fuel cell device and measures the temperatures of the installed sites;
It is determined whether or not the supply of power to the external load is being performed, and when the supply of power to the external load is being performed, the temperature is sequentially applied to the plurality of temperature measurement units in a predetermined first cycle. And a control unit that causes the plurality of temperature measurement units to sequentially measure temperatures at a predetermined second period different from the first period when power supply to the external load is not performed. It is characterized by.

  According to the fuel cell system of one embodiment of the present invention, the measurement cycle is different between when the power supply to the external load is executed and when the power supply to the external load is not executed. By operating, the fuel cell system can be operated efficiently.

It is a block diagram which shows an example of a structure of a fuel cell system provided with the fuel cell apparatus of one Embodiment of this invention. It is a block diagram which shows an example of a structure of the control part of one Embodiment of this invention. It is a timing chart which shows an example of the temperature measurement control which a control part performs in one Embodiment of this invention. It is a flowchart which shows an example of the temperature measurement control which a control part performs in one Embodiment of this invention.

  Hereinafter, the fuel cell system 1 in the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a configuration of a fuel cell system 1 including a fuel cell device 1a according to the present embodiment. In the following drawings, the same components will be described using the same reference numerals. A fuel cell system 1 shown in FIG. 1 includes a fuel cell device 1a, a hot water storage device 1b for storing hot water after heat exchange, a circulation pipe 24 for circulating water between these devices, and water in the circulation pipe 24. The circulation pump 16 is configured to circulate, the control unit 2 that controls the operation of the fuel cell device 1a and various devices, and the external load 3. In addition, it can also be set as the structure which does not provide the hot water storage apparatus 1b.

  The fuel cell device 1a generates power using a fuel gas supply device 14 that supplies raw fuel such as city gas, a reformer 8 that generates reformed gas containing hydrogen from the fuel gas and water, and the reformed gas and oxygen-containing gas. A cell stack 5 and an oxygen-containing gas supply device 15 for supplying an oxygen-containing gas to the cell stack 5 are provided. Further, the fuel cell device 1a burns unburned gas (unburned reformed gas, oxygen-containing gas, and fuel gas) that has not been used for power generation in the cell stack 5, and the reformer 8 or the cell stack is heated by the combustion heat. 5 is further provided with a combustion part 9 for heating 5, a combustion catalyst 11 for burning the combustion exhaust gas generated in the combustion part 9, and an exhaust part 10 for discharging the exhaust gas. The reformed gas is supplied via the reformed gas pipe 27, and the exhaust gas flows through the flow path in the fuel cell device 1a and is discharged to the outside air.

  In the fuel cell device 1a, the heat exchanger 6 that performs heat exchange between the exhaust heat generated by the power generation in the cell stack 5 and water, and the condensed water generated by the heat exchanger 6 are processed into pure water. The water tank 12 for storing the water (pure water) treated by the water treatment device 12 and the water treatment device 12 is provided, and the water tank 13, the water treatment device 12, and the heat exchanger 6 are connected to each other. The space is connected by a condensed water supply pipe 25. In addition, as the water treatment apparatus 12, it is preferable to use an ion exchange resin apparatus provided with an ion exchange resin. The water stored in the water tank 13 is supplied to the reformer 8 by a water pump 17 provided in a water supply pipe 26 connecting the water tank 13 and the reformer 8.

  Further, the fuel cell device 1a converts the DC power generated in the cell stack 5 into AC power and supplies it to the external load 3, and adjusts the supply amount of the converted power to the external load 3. 4, and each device constituting these can be housed in an outer case, whereby the fuel cell device 1 a that can be easily installed and transported can be obtained. The hot water storage device 1b includes a hot water storage tank 7 for storing hot water.

  In addition, the fuel cell system 1 includes thermocouples 36 installed at a plurality of predetermined sites in the fuel cell device 1a, and includes a temperature measurement unit that measures the temperatures of the installed sites at a predetermined cycle. In the present embodiment, the first temperature measurement unit 18 that measures the temperature of the combustion unit 9, the second temperature measurement unit 19 that measures the temperature of the exhaust unit 10 having the combustion catalyst 11, and the temperature of the reformer 8 are used. A third temperature measuring unit 20 for measuring, a fourth temperature measuring unit 21 for measuring the temperature of the cell stack 5, and an inlet water temperature measuring unit for measuring the water temperature of the water (circulated water flow) flowing into the inlet of the heat exchanger 6. A fifth temperature measurement unit 22 and a sixth temperature measurement unit 23 that is an outlet water temperature measurement unit that measures the temperature of water (circulated water flow) that is provided at the outlet of the heat exchanger 6 and flows through the outlet of the heat exchanger 6 are provided. It has been. Each of the temperature measuring units 18 to 23 is realized by a thermocouple 36, for example.

  For parts where temperature information is important in managing the operating state, for safety, provide two or more temperature measurement units in one part to avoid the risk of failure of one temperature measurement unit Is also possible. As a part where temperature information is important for safety in using the apparatus, for example, a first temperature measurement unit 18 that measures the temperature of the combustion unit 9 can be cited.

  Here, an operation method of the fuel cell system 1 shown in FIG. 1 will be described. In generating the reformed gas necessary for power generation of the cell stack 5, the control unit 2 operates the fuel gas supply device 14 and the water pump 17. Thereby, fuel gas and water are supplied to the reformer 8, and reforming gas containing hydrogen is generated by performing steam reforming in the reformer 8, and the fuel of the fuel cells in the cell stack 5. Supplied to the extreme layer side.

  On the other hand, the control unit 2 operates the oxygen-containing gas supply device 15 to supply the oxygen-containing gas to the oxygen electrode layer side of the fuel cell. In addition, the control part 2 burns the unburned gas which was not used for electric power generation in the cell stack 5 by operating the ignition device (ignition heater etc.) arrange | positioned at the combustion part 9. FIG. Thereby, the temperature of the reformer 8 and the cell stack 5 rises, and efficient power generation can be performed.

  The exhaust gas generated by the power generation of the cell stack 5 is purified by the purification device, and then supplied to the heat exchanger 6 to exchange heat with water flowing through the circulation pipe 24. High temperature water generated by heat exchange in the heat exchanger 6 flows through the circulation pipe 24 and is stored in the hot water storage tank 7. Further, water contained in the exhaust gas discharged from the cell stack 5 by heat exchange in the heat exchanger 6 becomes condensed water, flows through the condensed water supply pipe 25, and is supplied to the water treatment device 12.

  The condensed water is made pure water in the water treatment device 12 and supplied to the water tank 13. The water stored in the water tank 13 flows through the water supply pipe 26 by the water pump 17 and is supplied to the reformer 8. Thus, by effectively using the condensed water, it is not necessary to supply water from the outside, and an independent operation can be performed. In addition, in the structure which does not provide the hot water storage apparatus 1b, you may produce | generate condensed water by providing a cooling device instead of the heat exchanger 6. FIG.

  In the above-described example, the fuel cell device 1 a configured to supply only the condensed water generated in the heat exchanger 6 to the reformer 8 has been described, but tap water is used as water to be supplied to the reformer 8. In this case, as a water treatment device for removing impurities contained in tap water, for example, an activated carbon filter, a reverse osmosis membrane device, an ion exchange resin device, etc. are connected in this order. By this, pure water can be purified efficiently. Even when tap water is used, each device is connected so that pure water generated by the water treatment device is stored in the water tank 13.

  Next, the configuration of the control unit 2 of the present embodiment will be described with reference to FIG. The control unit 2 includes a power supply state determination unit 30 that continuously determines whether or not power supply from the fuel cell device 1a to the external load is being executed, an operation state management unit 31 that manages the operation state, A channel switching device 32 for selecting one of the temperature information signals from the temperature measurement unit, an amplifier 33 which is an amplifier circuit for amplifying the temperature information analog signal, and converting the temperature information from an analog signal to a digital signal. And an arithmetic processing unit (Central Processing Unit: abbreviated as CPU) 35 that performs an operation for determining an operation state from temperature information.

  In addition, an operation signal 38 is transmitted from the power conditioner 4 to the power supply state determination unit 30 to transmit whether or not the power conditioner 4 is operating, and the channel switching device 32 receives a channel switching command from the power supply state determination unit 30. 37 to switch channels. The power supply state determination unit 30 not only detects whether or not the power conditioner 4 is operating based on the operation signal 38, but can also determine whether or not the power conditioner 4 is operating based on temperature information. It is.

  Here, since the control unit 2 reads the values of all the parts by switching the channels corresponding to the respective measurement parts every time for a plurality of temperature measurement parts, the time required for scanning all the channels is one channel. This is the time obtained by adding the number of channels to the number of channels. That is, as the number of temperature measurement parts increases, it takes time to scan all channels, and the response to temperature changes may be delayed. On the other hand, it is conceivable to add an amplifier circuit or an analog / digital converter. However, if the number is increased, the volume, weight and power consumption of the apparatus increase, and the apparatus becomes complicated and the apparatus cost increases. In addition, the channel switching speed can be increased to speed up the response to temperature changes, but in this case, the sampling time of each channel is shortened, and the signal level is relatively low with respect to the noise level. As a result, the signal-to-noise ratio (S / N ratio) decreases. Therefore, in this embodiment, the measurement cycle in the temperature measurement unit is varied depending on whether or not the supply of power to the external load is being executed.

Next, temperature measurement control performed by the control unit 2 in the present embodiment will be described using the timing chart of FIG. FIG. 3 shows a sampling time for temperature measurement and conditions for the change with respect to a graph TC showing a temperature change in a specific field region with time t on the horizontal axis and temperature T on the vertical axis. When the fuel cell system 1 is started, the power conditioner 4 is stopped to reduce power consumption, and can be operated only after power generation is possible. Here, the power generation start condition is that the temperature of a specific part is equal to or higher than a predetermined temperature, or the temperature of a plurality of parts is equal to or higher than a predetermined temperature. In addition, as a temperature measurement part which judges whether electric power generation is possible, for example, cell stack 5
The 4th temperature measurement part 21 which measures the temperature of can be used.

  When the fuel cell system 1 is activated, the control unit 2 causes a plurality of temperature measurement units to sequentially measure temperatures at a predetermined second period. When the temperature rises and the conditions for starting power generation are satisfied, here, for example, when TC exceeds a predetermined temperature T1, the power conditioner 4 is activated and power generation is started. The time period from the start of the fuel cell system 1 to the start of the power conditioner 4 is a time interval (at the time of starting) of the fuel cell device 1a, and the time interval during which the fuel cell device 1a is generating power after the start of the power conditioner 4 (During power generation).

  When power generation is started, the control unit 2 causes the plurality of temperature measurement units to sequentially measure temperatures in a first cycle that is different from the second cycle. Here, the time S2 per cycle in the second cycle is shorter than the time S1 per cycle in the first cycle. The temperature TC during power generation changes between T2 and T3 at the normal time.

  Next, a flow of temperature measurement control performed by the control unit 2 in the present embodiment will be described using the flowchart of FIG. The power supply state determination unit 30 determines whether or not the power conditioner 4 is in operation when starting measurement at each sampling time of temperature measurement of each part (step S1), and the power conditioner 4 is in operation. In this case, in step S3, the measurement update cycle is set as the first cycle, the update cycle is lengthened, and the sampling cycle is lengthened.

  In addition, when the inverter 4 is not in operation, the latest history of the temperature measurement result is referred to, and whether or not the temperature is changed by ΔT degrees (ΔT [° C.] / Min.) Or more per minute. Is further determined (step S2). If not changed by ΔT or more, the sampling cycle is shortened in step S4 by setting the measurement update cycle to the second cycle shorter than the first cycle. If it has changed by ΔT or more, in step S5, the measurement update period is set to a third period shorter than the second period, and the sampling period is further shortened. When the channel switching command 37 is output under the conditions determined by the power supply state determination unit 30 in this way and the temperature measurement of each part is sequentially performed and completed, the temperature measurement ends.

  In this way, when the fuel cell device 1a whose temperature rises continuously is started, a high response speed can be obtained by shortening the measurement time (sampling time) and shortening the update time. . Further, since the temperature change is small but a slight temperature difference affects the power generation operation of the fuel cell device 1a, the required temperature measurement accuracy is increased, and the power conditioner 4 operates to generate a strong noise tolerance. By increasing the time required for measurement (sampling time), the measurement accuracy can be improved. Furthermore, even when the fuel cell device 1a is stopped, the temperature sampling cycle can be made shorter than that during operation. Therefore, in the fuel cell device 1a having different temperature accuracy and response speed required for each operation stage, it is possible to perform temperature measurement control that satisfies each.

  The case where the time S2 per cycle in the second cycle is shorter than the time S1 per cycle in the first cycle has been described above. However, the sampling cycle may be changed in each cycle depending on the temperature measurement part. In addition, the method of changing the sampling period at each stage of control may be different for each temperature measurement site. For example, for the first temperature measurement unit (temperature measurement unit of the combustion unit 9), the time S2 per cycle is shortened as described above in order to accelerate the ignition detection of the combustion unit 9 in the second cycle (during startup). Is desirable.

  Conversely, for the second temperature measurement unit (temperature measurement unit of the exhaust unit 10), it is considered that the time S1 per cycle is shortened in order to accelerate the misfire detection of the combustion unit 9 in the first cycle (during power generation). It is done. When the misfire of the combustion unit 9 occurs, the reformer 8 and the cell stack 5 cannot be maintained at a high temperature, and as a result, the amount of power generation may be reduced. Is important for managing the driving condition. Also, when the temperature rises too much, the reaction in the cell stack 5 is shut down, and after entering the recovery mode, the gas, air and water are only supplied, circulated and discharged for a certain period of time and then restarted. It is also possible to perform control.

  Of course, it is possible to perform not only two-stage control of the first and second periods, but also three or more stages, such as providing a third period of the intermediate stage. Sometimes, similar control may be performed.

DESCRIPTION OF SYMBOLS 1 Fuel cell system 1a Fuel cell apparatus 1b Hot water storage apparatus 2 Control part 3 External load 4 Power conditioner 5 Cell stack 6 Heat exchanger 7 Hot water storage tank 8 Reformer 9 Combustion part 10 Exhaust part 11 Combustion catalyst 12 Water treatment apparatus 13 Water Tank 14 Fuel gas supply device 15 Oxygen-containing gas supply device 16 Circulation pump 17 Water pump 18 First temperature measurement unit 19 Second temperature measurement unit 20 Third temperature measurement unit 21 Fourth temperature measurement unit 22 Fifth temperature measurement unit 23 First 6 Temperature Measurement Unit 24 Circulation Piping 25 Condensed Water Supply Pipe 26 Water Supply Pipe 27 Reformed Gas Piping 30 Power Supply State Determination Unit 31 Operation State Management Unit 32 Channel Switching Device 33 Amplifier 34 Analog / Digital Converter 36 Thermocouple 37 Channel Switching Command 38 Operation signal

Claims (5)

A fuel cell device comprising a fuel cell that generates power using fuel gas and oxygen-containing gas;
A temperature measuring unit that is installed at a plurality of predetermined sites in the fuel cell device and measures the temperatures of the installed sites;
It is determined whether or not the supply of power to the external load is being performed, and when the supply of power to the external load is being performed, the temperature is sequentially applied to the plurality of temperature measurement units in a predetermined first cycle. And a control unit that causes the plurality of temperature measurement units to sequentially measure temperatures at a predetermined second period different from the first period when power supply to the external load is not performed. Battery system.   2. The fuel cell system according to claim 1, wherein the power supply to the external load is not executed when the fuel cell device is activated. The fuel cell device includes a combustion section that burns with a fuel gas and an oxygen-containing gas that have not been used in the power generation,
The temperature measurement unit includes a first temperature measurement unit that measures the combustion unit, and a time per cycle of the first temperature measurement unit at the start of the fuel cell device in the first cycle is the second time. 3. The fuel cell system according to claim 1, wherein the fuel cell system is shorter than a time per cycle of the first temperature measurement unit in the cycle. The fuel cell device has an exhaust part including a combustion catalyst that combusts combustion exhaust gas generated in the combustion part,
The temperature measurement unit includes a second temperature measurement unit that measures the exhaust unit, and the time per cycle of the second temperature measurement unit in the second cycle is the start of the fuel cell device in the first cycle. The fuel cell system according to any one of claims 1 to 3, wherein the time is shorter than a time per cycle of the second temperature measurement unit at the time.   The fuel cell system according to any one of claims 1 to 4, wherein a time per cycle in the second cycle is shorter than a time per cycle in the first cycle.

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