JP2010037158A - Reformer and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of surely judging the starting of steam generation supplied to a reforming part and reducing its manufacturing cost. <P>SOLUTION: The fuel cell system is equipped with a reforming part 21 which generates a fuel gas containing hydrogen from a fuel to be reformed and reforming water and supplies to a fuel electrode 11 of a fuel cell 10, an evaporation part 26 for generating steam by evaporating the reforming water and supplying to the reforming part 21, a burner 25 for heating the reforming part 21, a temperature sensor 21c for detecting the temperature θ1 at the outlet part of the reforming part 21, and a controller 1 for controlling the reforming part 21, the evaporation part 26 and the burner 25. The controller 1 determines that steam is generated when the temperature rise rate α1 at the outlet part of the reforming part 21 based on the temperature sensor 21c reaches to the standard temperature rise rate αm or above. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reformer and a fuel cell system.

  Conventionally, a reforming unit that generates reformed gas containing hydrogen from reforming fuel and reformed water, an evaporation unit that evaporates the reformed water to generate steam and supply the reformed unit, and a reforming unit are provided. As a reformer having a combustion section for heating and a control device for controlling the reforming section, the evaporation section, and the combustion section, those described in Patent Document 1 and Patent Document 2 are known. The reformer described in Patent Document 1 has a temperature sensor that measures the temperature of water vapor supplied from the evaporation unit to the reforming unit, and the temperature of the water vapor based on this temperature sensor is within a set temperature range. If not, the control device determines that the reforming reaction is abnormal. Then, the control device increases the amount of water supplied to the reforming unit by increasing the amount of reforming water to the evaporation unit when the temperature of the water vapor is larger than the set temperature range, and the temperature of the steam is within the set temperature range. When smaller than this, the amount of reforming water to the evaporation section is decreased to reduce the amount of water vapor supplied to the reforming section. According to this reformer, it is considered that the steam ratio in the reforming section can be easily maintained appropriately, and the state of the reforming reaction can be satisfactorily maintained.

Further, the reformer described in Patent Document 2 has a temperature sensor that measures the temperature of the reforming unit, and the amount of combustion in the combustion unit is increased or decreased by the temperature of the reforming unit based on this temperature sensor. Thus, the temperature of the reforming section is controlled. According to this reformer, it is considered that the temperature of the reforming section can be easily maintained appropriately and the state of the reforming reaction can be satisfactorily maintained.
JP 2005-225725 A Japanese Patent No. 3772619

  However, in the reformer described in Patent Document 1, a temperature sensor for measuring the temperature of water vapor supplied from the evaporation unit to the reforming unit is provided in the evaporation unit. Manufacturing costs will rise. Further, since the water vapor is detected by the evaporation unit, there may be a case where the water vapor does not sufficiently flow into the reforming unit. In this case, since carbon in the reforming fuel is too much with respect to the water vapor supplied to the reforming section, coking may occur and the reforming catalyst may be deteriorated.

  Further, in the reforming apparatus described in Patent Document 2, although the temperature sensor is not provided in the evaporation unit, the cost of parts can be reduced, but the control of the reforming water (steam) supplied to the reforming unit is possible. Is not described.

  The present invention has been made in view of the conventional problems, and it is possible to reliably determine the start of generation of water vapor supplied to the reforming unit and to reduce the manufacturing cost. An apparatus and a fuel cell system are provided.

  In order to solve the above problems, the reformer according to claim 1 is characterized in that a reforming unit that generates reformed gas containing hydrogen from reforming fuel and reformed water, and evaporating the reformed water. An evaporation unit that generates steam to supply the reforming unit, a combustion unit that heats the reforming unit, temperature detection means that detects a temperature of an outlet of the reforming unit, the reforming unit, A reforming device comprising a control device for controlling the evaporation unit and the combustion unit, wherein the control device has a temperature increase rate at the outlet of the reforming unit based on the temperature detection means that is equal to or greater than a predetermined value. It is determined that the generation of the water vapor is started.

  According to a second aspect of the present invention, there is provided a reforming device according to the first aspect, wherein the control device is configured so that a predetermined time elapses after the reforming water is supplied to the evaporating unit. When the temperature increase rate does not exceed a predetermined value, it is determined that the water vapor generation is abnormal.

  The reformer according to claim 3 is characterized in that a reforming unit that generates reformed gas containing hydrogen from reforming fuel and reformed water, and steam that is generated by evaporating the reformed water to generate the reformed gas. An evaporating unit to be supplied to the unit, a combustion unit for heating the reforming unit, a temperature detection means for detecting the temperature of the outlet of the combustion unit, and a control device for controlling the reforming unit, the evaporating unit and the combustion unit The control device determines that the generation of the water vapor is started when the temperature decrease rate of the combustion section becomes equal to or higher than a predetermined value.

  According to a fourth aspect of the present invention, there is provided a characteristic of the reformer according to the third aspect, wherein the controller reduces the temperature reduction rate of the combustion section even after a predetermined time has elapsed since the reforming water was supplied to the evaporation section. When not exceeding the predetermined value, it is determined that the water vapor generation is abnormal.

  The fuel cell system according to claim 5 is characterized in that in the fuel cell system in which the fuel gas is supplied to the fuel electrode and the oxidant gas is supplied to the oxidant electrode to generate electric power, the fuel cell system according to any one of claims 1 to 4 The reformed gas generated by the described reformer may be used as the fuel gas.

  In the reforming apparatus according to claim 1, when the temperature of the outlet of the reforming section is detected by the temperature detecting means, and the temperature rise rate becomes a predetermined value or more, the control apparatus starts generating steam. It is determined that Since the gas in the reforming section hardly moves before the start of the supply of water vapor to the reforming section, heat transfer to the outlet section of the reforming section is mainly performed by conduction. For this reason, the rate of temperature increase at the outlet of the reforming unit is not so large. However, when the steam generated in the evaporation section is supplied to the reforming section, the steam is heated by the combustion gas, and the heated steam moves to the outlet section of the reforming section. For this reason, the temperature of the outlet portion increases rapidly, and the temperature increase rate increases. It is possible to reliably determine the generation of water vapor based on the temperature increase rate. Further, since the start of the generation of water vapor is determined based on the temperature of the outlet of the reforming unit detected by the temperature detection means, it is not necessary to provide a temperature sensor in the evaporation unit. Therefore, according to this reforming apparatus, it is possible to reliably determine the start of generation of water vapor supplied to the reforming section, and to reduce the manufacturing cost. Further, since the temperature detecting means is provided at the outlet of the reforming section, when the rate of temperature increase exceeds a predetermined value, the entire reforming section is already filled with water vapor. Therefore, it is possible to suppress the supply of the reforming fuel to the reforming unit in a state where water vapor is insufficient, and it is possible to suppress the deterioration of the reforming catalyst due to coking.

  In the reforming apparatus according to claim 2, when the temperature increase rate at the outlet of the reforming unit does not exceed a predetermined value even after a predetermined time has elapsed since the reforming water was supplied to the evaporation unit, steam generation is performed. Determined as abnormal. If heating continues even though steam is not supplied to the reforming section, not only does the reforming section deteriorate and durability deteriorates, but energy is lost due to an increase in the time to burn combustion fuel wastefully. . Therefore, if it is determined that the water vapor generation is abnormal based on the temperature rise rate at the outlet of the reforming unit, if a measure such as stopping the reforming device is taken, the decrease in durability can be suppressed and the loss of energy can be suppressed. .

  In the reforming apparatus according to claim 3, when the temperature of the combustion section is detected by the temperature detection means and the temperature reduction rate becomes equal to or higher than a predetermined value, the control apparatus determines that the generation of steam is started. When the combustion section is ignited in a state where the entire reforming section is not filled with water vapor, the temperature of the combustion section rapidly increases locally and is maintained at a substantially constant temperature by the control state. However, as a result of experiments by the inventor, it was confirmed that when the steam generated in the evaporation section is supplied into the reforming section, the temperature of the combustion section is temporarily lowered. Therefore, it is possible to reliably determine the generation of water vapor based on the temperature decrease rate. Further, since it is determined whether or not the generation of water vapor is started based on the temperature of the combustion part detected by the temperature detection means, it is not necessary to provide a temperature sensor in the evaporation part. Therefore, according to this reforming apparatus, it is possible to reliably determine the start of generation of water vapor supplied to the reforming section, and to reduce the manufacturing cost.

  In the reforming apparatus according to claim 4, when the temperature decrease rate of the combustion section does not become a predetermined value or more even after a predetermined time has elapsed after supplying the reforming water to the evaporation section, it is determined that the steam generation is abnormal. The If heating continues even though steam is not supplied to the reforming section, not only does the reforming section deteriorate and durability deteriorates, but energy is lost due to an increase in the time to burn combustion fuel wastefully. . Therefore, when it is determined that the steam generation is abnormal based on the temperature decrease rate of the combustor, if a measure such as stopping the reformer is performed, a decrease in durability can be suppressed and energy loss can be suppressed.

  In the fuel cell system according to claim 5, since the reformed gas generated by the reformer according to any one of claims 1 to 4 is used as fuel gas, the reformed gas is supplied to the reforming unit. The start of the generation of water vapor can be determined with certainty, and the manufacturing cost can be reduced.

  Embodiments 1 and 2 of the reformer and the fuel cell system according to the present invention will be described below. FIG. 1 is a schematic diagram showing an outline of the fuel cell system according to the first embodiment. The fuel cell system includes a fuel cell 10, a reformer 20 that generates a reformed gas (fuel gas) containing hydrogen gas necessary for the fuel cell 10, and a controller 1 that controls the fuel cell system.

  The fuel cell 10 includes a fuel electrode 11, an air electrode 12 that is an oxidant electrode, and an electrolyte 13 interposed between the electrodes 11 and 12, and supplies the reformed gas supplied to the fuel electrode 11 and the air electrode 12. Electric power is generated using air (cathode air), which is the oxidant gas.

  The reformer 20 steam reforms the reforming fuel and supplies the hydrogen-rich reformed gas to the fuel cell 10, and includes a reforming unit 21, a cooling unit (heat exchanging unit) 22, carbon monoxide. A shift reaction unit (hereinafter referred to as a CO shift unit) 23, a carbon monoxide purification unit (hereinafter referred to as a CO purification unit) 24, a burner 25, and an evaporation unit 26 are included. Examples of the reforming fuel include natural gas, gas fuel for reforming such as LPG, and liquid fuel for reforming such as kerosene, gasoline, and methanol. In the present embodiment, description will be made on natural gas.

  The reforming unit 21 generates and derives a reformed gas from a mixed gas that is a reforming raw material in which reforming water is mixed with the reforming fuel. The reforming portion 21 is formed in a bottomed cylindrical shape, and includes an annular folded channel 21a extending along the axis in the annular cylindrical portion.

  The return channel 21a of the reforming unit 21 is filled with a catalyst 21b (for example, a Ru or Ni-based catalyst), and the reforming fuel and the steam supplied from the cooling unit (heat exchange unit) 22 are supplied. A gas mixture with water vapor introduced from the pipe 51 is reacted and reformed by the catalyst 21b to generate hydrogen gas and carbon monoxide gas (so-called steam reforming reaction). At the same time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide generated in the steam reforming reaction reacts with steam to transform into hydrogen gas and carbon dioxide. These generated gases (so-called reformed gas) are led to a cooling unit (heat exchange unit) 22. The steam reforming reaction is an endothermic reaction, and the carbon monoxide shift reaction is an exothermic reaction. A temperature sensor 21c is disposed at the outlet of the reforming unit 21, and the temperature θ1 at the outlet of the reforming unit 21 can be detected by the temperature sensor 21c. Here, the “outlet part of the reforming part” is preferably within 100 mm, more preferably within 50 mm from the outlet of the reforming part 21 to the inside of the reforming part 21. 100 mm or less is desirable on the outside of the reforming unit 21 from the outlet of the reforming unit 21, and more desirably 50 mm or less. When a pipe line exists between the reforming unit 21 and the immediately following device, the inside of this pipe line is also included in the “exit part of the reforming unit”, and a desirable distance inside the reforming unit 21 is the reforming unit 21. The desired distance on the outside of the reforming unit 21 is based on the outlet of the pipeline. This temperature sensor 21c is a “temperature detection means”.

  The cooling unit (heat exchange unit) 22 is a heat exchanger in which heat exchange is performed between the reformed gas derived from the reforming unit 21 and a mixed gas of reforming fuel and reforming water (steam). (Heat exchanging section), the reformed gas having a high temperature is cooled by a mixed gas having a low temperature and led to the CO shift section 23, and the mixed gas is heated by the reformed gas and led to the reforming section 21. It is supposed to be.

  Specifically, a reforming fuel supply pipe 41 connected to a fuel supply source (not shown) (for example, a city gas pipe) is connected to the cooling section (heat exchange section) 22. The reforming fuel supply pipe 41 is provided with a fuel pump 42, a desulfurizer 46, and a reforming fuel valve 43 in order from the upstream. The reforming fuel valve 43 opens and closes the reforming fuel supply pipe 41. The fuel pump 42 is reforming fuel supply means for supplying reforming fuel and adjusting the supply amount. The desulfurizer 46 reduces the sulfur content (for example, sulfur compound) in the fuel. Of the fuel supplied from the fuel supply source, the fuel supplied to the reforming unit 21 and reformed is called reforming fuel, and the fuel supplied to the burner 25 and combusted is called combustion fuel.

  A combustion fuel supply pipe 44 connected to a combustion air supply pipe 64 connected to the burner 25 is connected between the desulfurizer 46 and the reforming fuel valve 43 of the reforming fuel supply pipe 41. ing. A combustion fuel valve 45 is provided in the combustion fuel supply pipe 44. The combustion fuel valve 45 opens and closes the combustion fuel supply pipe 44. When the fuel pump 42 is driven and the reforming fuel valve 43 is closed and the combustion fuel valve 45 is opened, combustion fuel is supplied to the burner 25, and the fuel pump 42 is driven and the reforming fuel valve. When 43 is opened and the combustion fuel valve 45 is closed, the reforming fuel is supplied to the reforming unit 21.

  Further, a steam supply pipe 51 connected to the evaporation section 26 is connected between the reforming fuel valve 43 and the cooling section (heat exchange section) 22 of the reforming fuel supply pipe 41. The water vapor supplied from the evaporation unit 26 is mixed with the reforming fuel, and the mixed gas is supplied to the reforming unit 21 through the cooling unit (heat exchange unit) 22.

  The CO shift unit 23 is a unit that reduces carbon monoxide in the reformed gas supplied from the reforming unit 21 through the cooling unit (heat exchange unit) 22, that is, a carbon monoxide reducing unit. The CO shift unit 23 includes a folded channel 23a extending along the vertical direction. The return channel 23a is filled with a catalyst 23b (for example, a Cu—Zn-based catalyst). In the CO shift unit 23, carbon monoxide and water vapor contained in the reformed gas introduced from the cooling unit (heat exchange unit) 22 react with the catalyst 23 b to be converted into hydrogen gas and carbon dioxide gas. A carbon oxide shift reaction has occurred. This carbon monoxide shift reaction is an exothermic reaction.

  The CO purifying unit 24 further reduces the carbon monoxide in the reformed gas supplied from the CO shift unit 23 and supplies it to the fuel cell 10, that is, a carbon monoxide reducing unit. The CO purifying unit 24 is formed in a cylindrical shape and is provided so as to cover the outer peripheral wall of the evaporation unit 26. The inside of the CO purification unit 24 is filled with a catalyst 24a (for example, a Ru or Pt catalyst).

  A connecting pipe 89 connected to the CO shift unit 23 and a reformed gas supply pipe 71 connected to the fuel electrode 11 of the fuel cell 10 are connected to the lower side wall surface and the upper side wall surface of the CO purification unit 24, respectively. Yes. An oxidation air supply pipe 61 is connected to the connection pipe 89. As a result, the reforming gas from the CO shift unit 23 and the oxidizing air from the atmosphere are introduced into the CO purification unit 24. The oxidizing air supply pipe 61 is provided with an oxidizing air pump 62 and an oxidizing air valve 63 in order from the upstream. The oxidizing air pump 62 supplies oxidizing air and adjusts the supply amount. The oxidation air valve 63 opens and closes the oxidation air supply pipe 61.

  Therefore, carbon monoxide in the reformed gas introduced into the CO purification unit 24 reacts (oxidizes) with oxygen in the oxidizing air to become carbon dioxide. This reaction is an exothermic reaction and is promoted by the catalyst 24a. Thereby, the reformed gas is derived by further reducing the carbon monoxide concentration (10 ppm or less) by the oxidation reaction, and is supplied to the fuel electrode 11 of the fuel cell 10.

  The CO purification unit 24 is connected to the inlet of the fuel electrode 11 of the fuel cell 10 via a reformed gas supply pipe 71, and the burner 25 is connected to the outlet of the fuel electrode 11 via an offgas supply pipe 72. Has been. The bypass pipe 73 bypasses the fuel cell 10 and directly connects the reformed gas supply pipe 71 and the offgas supply pipe 72. The reformed gas supply pipe 71 is provided with a first reformed gas valve 74 between the branch point of the bypass pipe 73 and the fuel cell 10. The off gas supply pipe 72 is provided with an off gas valve 75 between the junction with the bypass pipe 73 and the fuel cell 10. A second reformed gas valve 76 is provided in the bypass pipe 73.

  During the start-up operation, the first reformed gas valve 74 and the offgas valve 75 are closed and the second reformed gas valve 76 is opened in order to avoid supplying reformed gas having a high carbon monoxide concentration from the reformer 20 to the fuel cell 10. During the steady operation (power generation operation), the first reformed gas valve 74 and the offgas valve 75 are opened and the second reformed gas valve 76 is closed in order to supply the reformed gas from the reformer 20 to the fuel cell 10. .

  A cathode air supply pipe 67 is connected to the inlet of the air electrode 12 of the fuel cell 10, and an exhaust pipe 82 is connected to the outlet of the air electrode 12. Air is supplied to the air electrode 12, and off-gas is exhausted. The cathode air supply pipe 67 is provided with a cathode air pump 68 and a cathode air valve 69 in order from the upstream. The cathode air pump 68 supplies cathode air and adjusts the supply amount. The cathode air valve 69 opens and closes the cathode air supply pipe 67.

  The burner 25 generates combustion gas for heating the reforming unit 21 and supplying heat necessary for the steam reforming reaction, and a lower end portion is inserted into the inner peripheral wall of the reforming unit 21 to form a space. Is placed. In the burner 25, combustion fuel, reformed gas or anode off gas (these are combustible gases) supplied to the burner 25 are combusted by the combustion air supplied to the burner 25 to generate high-temperature combustion gas. To do. This combustion gas is formed between the reforming section 21 and the heat insulating section 28 and between the heat insulating section 28 and the evaporation section 26 and disposed so as to heat the reforming section 21 and the evaporation section 26. It flows through the flow path 27, passes through the exhaust pipe 81, and is discharged to the outside as combustion exhaust gas. The combustion gas heats the reforming catalyst 21a of the reforming unit 21 so as to be in the active temperature range, and heats the evaporation unit (heat exchange unit) 22 to generate steam. Here, the burner 25 and the combustion gas flow path 27 are “combustion portions”.

  The combustion air supply pipe 64 is provided with a combustion air pump (combustion oxidant gas supply means) 65 and a combustion air valve 66. The combustion air pump 65 sucks combustion air from the atmosphere and discharges it to the burner 25, and adjusts the amount of combustion air supplied to the burner 25 in accordance with a command from the control device. The combustion air valve 66 opens and closes the combustion air supply pipe 64 in accordance with a command from the control device.

  The evaporation unit 26 evaporates the reformed water to generate water vapor, and supplies the water vapor to the reforming unit 21 via the cooling unit (heat exchange unit) 22. The evaporator 26 is formed in a cylindrical shape so as to cover and contact the outer peripheral wall of the combustion gas passage 27.

  A water supply pipe 52 connected to a reforming water tank (not shown) is connected to a lower portion (for example, a lower portion of the side wall surface and a bottom surface) of the evaporation section 26. A water vapor supply pipe 51 is connected to the upper part (for example, the upper part of the side wall surface) of the evaporation unit 26. The reformed water introduced from the reformed water tank is heated by the heat from the combustion gas and the heat from the CO purification unit 24 in the course of flowing through the evaporation unit 26 to become water vapor, and the steam supply pipe 51 and It is led out to the reforming unit 21 via a cooling unit (heat exchange unit) 22. The water supply pipe 52 is provided with a reforming water pump 53 and a reforming water valve 54 in order from the upstream. The reforming water pump 53 supplies reforming water to the evaporation unit 26 and adjusts the reforming water supply amount. The reforming water valve 54 opens and closes the water supply pipe 52.

  A temperature sensor 21c, pumps 42, 53, 65, 62, 68, valves 43, 45, 54, 63, 66, 69, 74, 75, 76 and a burner 25 are electrically connected to the control device 1. Has been. The fuel cell system is controlled by the control device 1.

  The operation of the fuel cell system configured as described above will be described with reference to FIGS. FIG. 2 is a flowchart of the control program. FIG. 3 is a graph of the temperature θ1 at the outlet of the reforming unit 21. Note that θ3 in FIG. 3 is the temperature of the evaporator 26, which is a temperature measured by a temperature sensor disposed near the outlet of the evaporator 26 of the water vapor supply pipe 51. However, in this embodiment, a temperature sensor for measuring the temperature θ3 is not provided, but the temperature θ3 is shown in FIG. 3 for comparison with the temperature θ1 at the outlet of the reforming unit 21.

  When the fuel cell system is stopped, the pumps 42, 53, 65, 62, 68 are stopped, and the valves 43, 45, 54, 63, 66, 69, 74, 75, 76 are closed. is there. In step S10, when a start instruction is issued to the fuel cell system (time T0 in FIG. 3), the combustion air valve 66 is opened and the combustion air pump 65 is driven in step S12. Further, the combustion fuel valve 45 is opened, the fuel pump 42 is driven, and the burner 25 is ignited. Thereby, although the reforming part 21 is heated, since the gas in the reforming part 21 hardly moves, conduction to the outlet part of the reforming part 21 is mainly performed by conduction. Therefore, the temperature θ1 at the outlet of the reforming unit 21 rises slowly. At this time, the combustion fuel passes through the combustion fuel supply pipe 44 and is mixed with and mixed with the combustion air in the combustion air supply pipe 64, and the premixed gas passes through the combustion air supply pipe 64 to the burner 25. Supplied. Further, the reforming water valve 54 is opened and the reforming water pump 53 is driven. Further, the second reformed gas valve 76 is opened. As a result, the reforming water is supplied to the evaporation section 26 and the reforming water is heated by the combustion gas discharged from the burner 25, so that the temperature θ3 of the evaporation section 26 rises slowly. And when water vapor | steam generate | occur | produces in the evaporation part 26, temperature (theta) 3 of the evaporation part 26 will rise rapidly (time T1 of FIG. 3). At this time, since the second reformed gas valve 76 is opened, the water vapor generated in the evaporation unit 26 is converted into the water vapor supply pipe 51, the cooling unit (heat exchange unit) 22, the reforming unit 21, and the cooling unit (heat exchange unit). ) 22, CO shift section 23, connection pipe 89, CO purification section 24, reformed gas supply pipe 71, bypass pipe 73 and off-gas supply pipe 72 to flow into burner 25. Further, the reformed portion 21 and the gas in the pipe pushed by the water vapor flow into the burner 25 through the same route.

  In step S13, it is checked whether or not a predetermined time Tm has elapsed since the reforming water was supplied to the evaporator 26. When the predetermined time Tm has elapsed, in step S15, it is determined that there is an abnormality in water vapor generation, a notification to that effect is made, and the fuel cell system is stopped. Here, during the predetermined time Tm, when the reforming water pump 53 or the like is operating normally and a predetermined amount of reforming water is supplied from the water supply pipe 52 to the evaporation unit 26, the steam generated in the evaporation unit 26 is generated. It is obtained based on the time to reach the reforming unit 21 (time from time T0 to time T2 in FIG. 3). Specifically, the time from time T0 to time T2 is measured in advance by a test, and a predetermined time Tm is obtained by adding a margin time in anticipation of a measurement error or the like to the time. When step S15 is executed, sufficient steam does not reach the reforming unit 21 even after the predetermined time Tm has elapsed. For example, a predetermined amount of water reaches the evaporation unit 26 due to abnormality of the reforming water pump 53 or the like. The case where reformed water is not supplied is considered. In such a case, by stopping the fuel cell system in step S15, it is possible to suppress a decrease in durability and to suppress energy loss.

  If the predetermined time Tm has not elapsed, in step S14, the temperature θ1 of the outlet of the reforming unit 21 is input from the temperature sensor 21c, and the temperature increase rate α1 of the temperature θ1 has become equal to or higher than the reference temperature increase rate αm. It is investigated whether or not. When the temperature increase rate α1 is less than the reference temperature increase rate αm, it is determined that sufficient steam does not reach the reforming unit 21, and the process returns to step S13. When the temperature increase rate α1 is equal to or higher than the reference temperature increase rate αm (time T2 in FIG. 3), it is determined that sufficient steam reaches the reforming unit 21 and steam is generated in the evaporation unit 26 (step S16). .

  Before the supply of water vapor to the reforming unit 21 starts, the gas in the reforming unit 21 hardly moves, so heat transfer to the outlet of the reforming unit 21 is mainly performed by conduction. For this reason, the temperature increase rate α1 at the outlet of the reforming unit 21 is not so large. However, when the water vapor generated in the evaporation unit 26 is supplied to the reforming unit 21, the water vapor is heated by the combustion gas, and the heated water vapor moves to the outlet of the reforming unit 21. For this reason, the temperature θ1 of the outlet portion increases rapidly, and the temperature increase rate α1 increases. Therefore, it is possible to reliably determine the generation of water vapor based on the temperature increase rate α1.

  Then, after the warm-up operation of the fuel cell system, steady operation (power generation) is started (steps S17 to S19). In step S17, the combustion fuel valve 45 is closed, the supply of combustion fuel to the burner 25 is stopped, and the burner 25 is extinguished. However, the combustion air valve 66 is open, and the combustion air supplied through the combustion air supply pipe 64 causes the combustion gas remaining in the combustion section (the burner 25 and the combustion gas flow path 27) to be excessive or excessive. Water vapor is discharged from the exhaust pipe 81 and scavenged from the combustion section (burner 25 and combustion gas flow path 27). Therefore, reignition of the burner 25 in an unstable state can be suppressed.

  In step S18, the reforming fuel valve 43 is opened. As a result, the reforming fuel that has passed through the fuel supply pipe 41 is mixed with the reforming water (steam) supplied from the steam supply pipe 51. The mixed gas is supplied to the reforming unit 21 through the cooling unit (heat exchange unit) 22. The reforming fuel supplied to the reforming unit 21 is reformed to become reformed gas, and is a cooling unit (heat exchange unit) 22, a CO shift unit 23, a connection pipe 89, a CO purification unit 24, a reformed gas supply pipe. 71, flows into the burner 25 through the bypass pipe 73 and the off-gas supply pipe 72. Combustion air is supplied, the burner 25 is ignited, and the reformed gas is combusted.

  In step S19, after confirming the end of warm-up of the reformer 20, steady operation (power generation) is started. Note that the end of warm-up of the reformer 20 means that the reforming unit 21, the CO shift unit 23, the CO purifying unit 24, etc. reach a specified temperature to generate a specified amount of hydrogen and the CO concentration of the reformed gas. Refers to the state where the concentration drops below the specified concentration.

  During steady operation (power generation), the first reformed gas valve 74 and the offgas valve 75 are opened, and the combustion fuel valve 45 and the second reformed gas valve 76 are closed. As a result, the burner 25 is modified to contain anode off-gas from the fuel electrode 11 of the fuel cell 10 (hydrogen that has been supplied to the fuel electrode 11 of the fuel cell 10 and discharged without being consumed, or unreformed reforming fuel). Quality gas) is supplied, and the supply of fuel for combustion is stopped. However, the combustion air is supplied in the same manner as described above. In other words, the anode off gas is supplied to the burner 25 through the off gas supply pipe 72 and combustion air is supplied through the combustion air supply pipe 64. At this time, the burner 25 is not reheated by additionally burning a combustible gas such as a combustion fuel. This is a so-called reboundless system.

  In the fuel cell system according to Embodiment 1, when the water vapor generated in the evaporation unit 26 is supplied to the reforming unit 21, the water vapor is heated by the combustion gas, and the heated water vapor is discharged from the reforming unit 21. Therefore, the temperature θ1 at the outlet portion increases rapidly, and the temperature increase rate α1 increases. Therefore, it is possible to reliably determine the generation of water vapor based on the temperature increase rate α1. Further, since the start of the generation of water vapor is determined based on the temperature θ1 of the outlet of the reforming unit 21 detected by the temperature sensor 21c, it is not necessary to provide a temperature sensor in the evaporation unit 26. Therefore, according to this fuel cell system, it is possible to reliably determine the start of the generation of water vapor supplied to the reforming unit 21, and to reduce the manufacturing cost. Further, since the temperature sensor 21c is provided at the outlet of the reforming unit 21, when the temperature increase rate α1 becomes equal to or higher than the reference temperature increase rate αm, the entire reforming unit 21 is already filled with water vapor. Therefore, it is possible to suppress the supply of the reforming fuel to the reforming unit 21 in a state where water vapor is insufficient, and it is possible to suppress the deterioration of the reforming catalyst due to coking.

  The configuration of the fuel cell system of Embodiment 2 is substantially the same as that of Embodiment 1 shown in FIG. However, the temperature sensor 21c is not provided. A burner 25 shown in FIG. 4 is used.

  As shown in FIG. 4, the burner 25 includes a base portion 25a, a cylindrical combustion cylinder (cylinder) 25b provided on the base portion 25a and communicating with the base portion 25a, an off-gas nozzle 25c, and a temperature sensor 25e. ing. The burner 25 is ignited by an ignition electrode (not shown) in accordance with a command from the control device 1. Here, the temperature sensor 25e is “temperature detection means” for detecting the temperature θ2 of the burner 25.

  The base portion 25a includes a base plate 25a1 and a base casing 25a2 that covers and is fixed to the base plate 25a1. An off gas supply pipe 72 is connected to the base plate 25a1, and a base end of an off gas nozzle 25c is connected to an inner wall surface facing the space (internal space) 25a4 of the base plate 25a1. The off gas supply pipe 72 and the off gas nozzle 25c are communicated with each other through a connection path 25a3 formed in the base plate 25a1, and either the anode off gas or the reformed gas is introduced (supplied) to the off gas nozzle 25c. A combustion air supply pipe 64 is connected to the base casing 25a2, and combustion air or a premixed gas in which combustion air and combustion fuel are premixed is formed in the base 25a by the base plate 25a1 and the base casing 25a2. Introduced into the space 25a4. The port 64a through which either combustion air or premixed gas is introduced into the space 25a4 is the first introduction port.

  The upper end (one end) of the combustion cylinder 25b is connected to the base casing 25a2 of the base portion 25a, and the lower side (the other end) is opened. A disc-shaped partition plate 25b1 is provided in the middle of the combustion cylinder 25b in the longitudinal direction (for example, the lower end side from the middle), and partitions the combustion cylinder 25b in the longitudinal direction.

  The off-gas nozzle 25c is a nozzle in which an axial direction is provided inside the combustion cylinder 25b along the axial direction of the combustion cylinder 25b. The off-gas nozzle 25c extends in the space 25a4 and the combustion cylinder 25b toward the partition plate 25b1, passes through the center of the partition plate 25b1, and extends to the combustion space 25d. The tip portion of the off-gas nozzle 25c is closed, and a first injection port 25c1 is provided in a side surface portion (tip portion) slightly away from the tip. A plurality of the first injection ports 25c1 are provided so as to open to the side surface of the tip of the off-gas nozzle 25c. In the present embodiment, a plurality of (four in the present embodiment) first injection ports 25c1 are provided in the radial direction of the off-gas nozzle 25c. The first injection port 25c1 has a substantially circular cross section. The anode off gas or the reformed gas supplied from the base end side is ejected radially outward from the plurality of first injection ports 25c1 and introduced into the combustion space 25d. The off gas nozzle 25c is used not only for anode off gas but also for reformed gas bypassing the fuel cell 10.

  The combustion space 25d is a portion provided for burning the combustible gas, and is a space on the side where the tip of the off-gas nozzle 25c protrudes from the partition plate 25b1 in the combustion cylinder 25b. A portion of the combustion cylinder 25b that is at the tip of the partition plate 25b1 is a hood 25b3. The hood 25b3 is provided so as to cover the tip portion protruding from the partition plate 25b1 of the off-gas nozzle 25c.

  The partition plate 25b1 is a plate-like member fixed between the offgas nozzle 25c and the combustion cylinder 25b at a base end side position from the first injection port 25c1 of the offgas nozzle 25c. The partition plate 25b1 is fixed so as to be orthogonal to the off-gas nozzle 25c. The partition plate 25b1 has a flat plate shape in the present embodiment, but may not have a flat plate shape.

  A plurality of second injection ports 25b2 (16 in the embodiment) are provided around the off-gas nozzle 25c of the partition plate 25b1. The second injection port 25b2 is provided through the partition plate 25b1 in the axial direction. In the present embodiment, the second injection port 25b2 is provided to open in a direction parallel to the axial direction of the off-gas nozzle 25c. The second injection port 25b2 only needs to penetrate in the axial direction, and may not be parallel to the axial direction but may be inclined. The second injection port 25b2 has a substantially circular cross section.

  The base 25a, the combustion cylinder 25b, and the partition plate 25b1 constitute a housing 25g. Further, an internal space 25h (a space partitioned from the base 25a, the combustion cylinder 25b, and the partition plate 25b1) is formed in the housing 25g. The internal space 25h is formed by a space 25a4 and a portion on the base 25a side partitioned by the partition plate 25b1 in the space between the combustion cylinder 25b and the offgas nozzle 25c.

  In the case of diffusion combustion in which anode off gas or fuel gas is diffused and burned with combustion air, anode off gas or fuel gas is supplied to the off gas nozzle 25c, and combustion air is supplied so as to be ejected from the second injection port 25b2. . That is, the anode off-gas or fuel gas supplied to the off-gas nozzle 25c is ejected from the first injection port 25c1 toward the radially outer side of the off-gas nozzle 25c and is introduced into the combustion space 25d. Combustion air introduced into the space 25a4 in the base portion 25a is ejected from the second ejection port 25b2 toward the tip protruding side of the off-gas nozzle 25c, and is introduced into the combustion space 25d. In this case, the anode offgas or fuel gas ejected from the first injection port 25c1 toward the radially outer side of the offgas nozzle 25c is ejected from the second injection port 25b2 toward the tip protruding side of the offgas nozzle 25c. The flow of air makes the flow toward the tip protruding side of the off-gas nozzle 25c, and the flame 25f trying to spread outward is directed in the direction along the axial direction of the off-gas nozzle 25c.

  On the other hand, in the case of the premixed combustion in which the combustion fuel and the combustion air are premixed and the combustion fuel is premixed and combusted, the combustion fuel and the combustion air are premixed from the second injection port 25b2. Supplied to spout. That is, the premixed gas introduced into the space 25a4 in the base portion 25a is ejected from the second ejection port 25b2 toward the tip protruding side of the off-gas nozzle 25c and is introduced into the combustion space 25d. The premixed gas is supplied through the combustion air supply pipe 64.

  The temperature sensor 25e detects the radiation temperature of the flame 25f generated in the combustion space 25d of the burner 25 and transmits the detection result to the control device 1 (for example, a radiation thermometer). The temperature sensor 25e is, for example, a sheath thermocouple, and is inserted into the combustion space 25d through the base plate 25a1 of the base portion 25a and through the partition plate 25b1. The tip portion (slightly behind the tip 25e1) is a temperature measurement unit. The tip 25e1 of the temperature sensor 25e is provided so as to be closer to the partition plate 25b1 than the end 25c2 of the first injection port 25c1 on the partition plate 25b1 side, but is not limited thereto. Any position where the temperature measuring unit of the temperature sensor 25e can measure the radiation temperature of the flame 25f may be used. Specifically, the position of the temperature sensor 25e may be outside the flame surface 25f1 of the flame 25f in the burner 25 and the combustion gas flow path 27. Here, the flame surface refers to a boundary surface between a portion where a combustion reaction (oxidation reaction) of combustible gas (for example, anode off-gas, premixed gas (including combustion fuel)) occurs and other portions. In the present embodiment, a thermocouple is used as the temperature sensor 25e, but a thermistor may be used.

  The operation of the fuel cell system configured as described above will be described with reference to FIGS. FIG. 5 is a flowchart of the control program. FIG. 6 is a graph of the temperature θ2 of the burner 25. The flowchart of the control program shown in FIG. 5 is also substantially the same as that of the first embodiment shown in FIG. 2, and the same reference numerals are used for the same processing, and description thereof is omitted. Note that θ3 in FIG. 6 is the temperature of the evaporation unit 26, and in this embodiment also is a temperature measured by a temperature sensor disposed near the outlet of the evaporation unit 26, and the evaporation unit 26 is provided with a temperature sensor. Although not shown, the temperature θ3 is also shown in FIG. 6 for comparison with the temperature θ2 of the burner 25.

  When an activation instruction is issued to the fuel cell system in step S10 (time T0 in FIG. 6), the burner 25 is ignited in step S12. As a result, the entire reforming unit 21 is not warmed up suddenly, but the temperature θ2 of the burner 25 rapidly increases to a substantially constant temperature. Time T1 is the time at which water vapor is generated in the evaporation section 26, and is the same as in the first embodiment.

  In step S24, the temperature θ2 of the burner 25 is input from the temperature sensor 25e, and it is checked whether or not the temperature decrease rate α2 of the temperature θ2 is equal to or higher than the reference temperature decrease rate αn. When the temperature decrease rate α2 is less than the reference temperature decrease rate αn, it is determined that sufficient steam does not reach the reforming unit 21, and the process returns to step S13. When the temperature decrease rate α2 is equal to or higher than the reference temperature decrease rate αn (time T3 in FIG. 6), it is determined that sufficient steam has reached the reforming unit 21 and steam has been generated in the evaporation unit 26 (step S16). . Then, as in the first embodiment, after the warm-up operation of the fuel cell system, steady operation (power generation) is started (steps S17 to S19).

  In the fuel cell system according to the second embodiment, when the temperature θ2 of the burner 25 is detected by the temperature sensor 25e, and the temperature decrease rate α2 of the control device 1 becomes equal to or higher than the reference temperature decrease rate αn, water vapor is generated. It is determined that it has started. Here, when the burner 25 is ignited in a state where the entire reforming unit 21 is not filled with water vapor, the temperature θ2 of the burner 25 rapidly increases and is maintained at a substantially constant temperature depending on the control state. However, as a result of experiments by the inventors, when the water vapor generated in the evaporation unit 26 is supplied into the reforming unit 21, the temperature θ2 of the burner 25 temporarily decreases, and the temperature decrease rate α2 increases. confirmed. This is considered to be because the heat of the burner 25 is taken by the steam supplied to the reforming section 21 and this steam is discharged from the exhaust pipe 81 through the combustion gas flow path 27. Therefore, it is possible to reliably determine the start of water vapor generation based on the temperature decrease rate α2. Further, since the start of the generation of water vapor is determined based on the temperature θ2 of the burner 25 detected by the temperature sensor 25e, it is not necessary to provide a temperature sensor in the evaporation unit 26. Therefore, also with this fuel cell system, it is possible to reliably determine the start of the generation of water vapor supplied to the reforming unit 21, and to reduce the manufacturing cost.

  Further, in this fuel cell system, when the temperature decrease rate α2 of the burner 25 does not become the reference temperature decrease rate αn or more even after a predetermined time Tm has elapsed since the reforming water was supplied to the evaporation unit 26, water vapor is generated. Determined as abnormal. When it is determined that the water vapor generation is abnormal, by stopping the fuel cell system, a decrease in durability can be suppressed and energy loss can be suppressed.

  In the above, the fuel cell system of the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to these, and may be modified as appropriate unless it is contrary to the technical idea of the present invention. Needless to say, this is applicable.

1 is a schematic diagram showing an outline of a fuel cell system according to Embodiments 1 and 2. FIG. 4 is a flowchart of a control program according to the first embodiment. 4 is a graph of the temperature at the outlet of the reforming unit according to the first embodiment. It is sectional drawing of a combustion part according to embodiment. 10 is a flowchart of a control program according to the second embodiment. It is a graph of the temperature of a combustion part concerning Embodiment 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Control apparatus, 10 ... Fuel cell, 11 ... Fuel electrode, 12 ... Air electrode, 20 ... Reformer, 21 ... Reformer, 22 ... Cooling part (heat exchange part), 23 ... Carbon monoxide shift reaction part (CO shift section), 24 ... carbon monoxide purification section (CO purification section), 25 ... burner, 25a ... base, 25b ... combustion cylinder, 25b1 ... partition plate (planar plate member), 25b2 ... second outlet, 25c ... off gas nozzle, 25c1 ... first outlet, 25g ... housing, 25h ... internal space, 21c, 25e ... temperature detection means (temperature sensor), 26 ... evaporation part, 27 ... combustion gas flow path, 28 ... heat insulation part , 41 ... Fuel supply pipe, 42 ... Fuel pump, 43 ... Reforming fuel valve, 44 ... Combustion fuel supply pipe, 45 ... Combustion fuel valve, 46 ... Desulfurizer, 51 ... Steam supply pipe, 52 ... Feed water pipe 53 ... Reformed water pump, 54 ... Reformed water valve, DESCRIPTION OF SYMBOLS 1 ... Oxidation air supply pipe, 62 ... Oxidation air pump, 63 ... Oxidation air valve, 64 ... Combustion air supply pipe, 65 ... Combustion air pump, 66 ... Combustion air valve, 67 ... Cathode air supply Pipe ... 68 ... Cathode air pump, 69 ... Cathode air valve, 71 ... Reformed gas supply pipe, 72 ... Off gas supply pipe, 73 ... Bypass pipe, 74 ... First reformed gas valve, 75 ... Off gas valve, 76 ... Second reformed gas valve, 81, 82 ... exhaust pipe, 89 ... connecting pipe, [theta] 1 ... reformer outlet temperature, [theta] 2 ... combustion part temperature, [theta] 3 ... evaporation part temperature, [alpha] 1 ... temperature rise rate, [alpha] 2 ... temperature drop rate , Αm: reference temperature increase rate, αn: reference temperature decrease rate.

Claims (5)

A reforming unit that generates a reformed gas containing hydrogen from the reforming fuel and the reforming water; an evaporation unit that evaporates the reforming water to generate water vapor and supplies the steam to the reforming unit; and the reforming unit A reforming device comprising: a combustion unit that heats; a temperature detection unit that detects a temperature of an outlet of the reforming unit; and a control device that controls the reforming unit, the evaporation unit, and the combustion unit,
The said control apparatus determines that the production | generation of the said water vapor | steam was started when the temperature rise rate of the exit part of the said modification | reformation part based on the said temperature detection means became more than predetermined value.   2. The control device according to claim 1, wherein when the temperature increase rate at the outlet of the reforming unit does not exceed a predetermined value even after a predetermined time has elapsed since the reforming water was supplied to the evaporation unit, A reformer characterized by determining a production abnormality. A reforming unit that generates a reformed gas containing hydrogen from the reforming fuel and the reforming water; an evaporation unit that evaporates the reforming water to generate water vapor and supplies the steam to the reforming unit; and the reforming unit A reforming apparatus comprising: a combustion section that heats; a temperature detection means that detects a temperature of an outlet section of the combustion section; and a control device that controls the reforming section, the evaporation section, and the combustion section,
The said control apparatus determines with the production | generation of the said water vapor | steam being started when the temperature fall rate of the said combustion part becomes more than predetermined value.   4. The control device according to claim 3, wherein the controller determines that water vapor is abnormally generated when a temperature decrease rate of the combustion unit does not become a predetermined value or more even after a predetermined time has elapsed since the reforming water was supplied to the evaporation unit. The reformer characterized by performing. In a fuel cell system in which fuel gas is supplied to the fuel electrode and oxidant gas is supplied to the oxidant electrode to generate power,
A fuel cell system using the reformed gas generated by the reformer according to any one of claims 1 to 4 as the fuel gas.

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