JP2016207413A - Solid oxide type fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide type fuel battery system capable of improving ignition characteristics of a combustion part at a startup time, and suppressing backfire or the like when the combustion part is ignited.SOLUTION: A solid oxide fuel battery system includes a reformer 6, a solid oxide type fuel battery 3, a fuel collecting portion 20 where gas passing through the solid oxide type fuel battery gathers, a fuel supplier 10 for supplying fuel to the reformer, a first air supplier 11 for supplying power generation air, a second air supplier 12 for supplying reforming air, a combustor 5 for combusting gas blown from the fuel collecting portion and the power generation air, and an igniter 8 used for igniting the combustor. The fuel supplier and the first air supplier 11 are controlled so that the fuel concentration of the fuel collecting portion 20 is equal to or higher than a predetermined value by supplying the fuel and the power generation air at the start-up time, the second air supplier 12 is controlled so as to start supply of the reforming air or increase the supply amount, and then the igniter 8 is controlled so as to ignite the gas blown from the fuel collecting portion to the combustor.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a solid oxide fuel cell system.

  In the solid oxide fuel cell system, hydrocarbon fuel (fuel) is used not only for power generation of the solid oxide fuel cell but also for combustion in the combustion section (see Patent Document 1). For example, the ratio of the fuel used for power generation in the solid oxide fuel cell with respect to the total amount of fuel is set to about 60 to 80% (hereinafter sometimes referred to as fuel utilization rate), and the remaining about 20 to Often 40% of the fuel is used for combustion in the combustion section.

  Various methods have been proposed for the ignition sequence of the combustion section.

For example, Patent Document 2 discloses an ignition determination method at the time of starting a fuel cell system. When the gas temperature in the combustion region rises from a predetermined temperature T ₀ ° C to T ₁ ° C or more within a predetermined time, combustion is performed. It is described that it is determined that the part has been ignited, and if not, it is determined that the part has not been ignited. Moreover, in patent document 3, the control action after the ignition determination of a combustion part is described. Patent Document 4 describes a method for controlling an ignition heater when the combustion section is ignited.

  However, in the conventional example, a method for improving the ignition characteristics of the combustion section at the start of the solid oxide fuel cell system and suppressing the occurrence of backfire or the like at the ignition of the combustion section has not been sufficiently studied.

  An aspect of the present disclosure has been made in view of such circumstances, and improves the ignition characteristics of the combustion section at the start-up compared to the prior art, and backfire or the like occurs when the combustion section ignites. Provided is a solid oxide fuel cell system capable of suppressing this.

  In order to solve the above problems, a solid oxide fuel cell system according to one embodiment of the present disclosure includes a reformer that generates a reformed gas using fuel and reforming air, and the reformed gas and power generation air. A solid oxide fuel cell that generates electric power by reacting with each other, a fuel assembly part in which gas that has passed through the solid oxide fuel cell collects, a fuel supplier that supplies fuel to the reformer, and the solid oxide A first air supplier for supplying power generation air to the fuel cell, a second air supplier for supplying reforming air to the reformer, a gas blown from the fuel assembly, and power generation air. A combustion unit that burns, an igniter used to ignite the combustion unit, and a controller that controls the fuel supply unit, the first air supply unit, the second air supply unit, and the ignition unit, When the controller starts up the solid oxide fuel cell system, the controller The supply of reforming air is started by controlling the fuel supply unit and the first air supply unit so that the fuel concentration in the fuel assembly becomes equal to or higher than a predetermined value by supplying the fuel and the power generation air. Or after controlling the said 2nd air supply device so that supply amount may be increased, the solid oxide fuel cell system which controls the said ignition device to ignite the gas which blows off from the said fuel assembly part to the said combustion part.

  According to the solid oxide fuel cell system of one aspect of the present disclosure, it is possible to improve the ignition characteristics of the combustion unit at the time of startup and to suppress the occurrence of backfire or the like when the combustion unit is ignited.

FIG. 1 is a diagram illustrating an example of a solid oxide fuel cell system according to an embodiment. FIG. 2 is a time chart showing an example of the operation at the time of starting the solid oxide fuel cell system of the embodiment. FIG. 3 is a flowchart illustrating an example of an operation at the time of starting the solid oxide fuel cell system according to the embodiment. FIG. 4 is a diagram illustrating an example of a fuel assembly portion of the solid oxide fuel cell system according to the embodiment. FIG. 5 is a diagram illustrating an example of a flame formed in a combustion portion of a conventional solid oxide fuel cell system.

  Recently, further increase in power generation efficiency of fuel cells has been demanded due to an increase in demand for electric power and an increase in interest in environmental problems. In order to improve the power generation efficiency of the fuel cell, there are a method of increasing the power generation voltage of the fuel cell, a method of increasing the fuel utilization rate of the fuel cell, and the like. Since the former method requires the development of fuel cell materials, the latter method is considered promising.

  However, when the fuel utilization rate of the fuel cell is further increased, since a larger amount of reformed gas is used for power generation in the fuel cell, it is used as combustion fuel in the combustion section as the amount of reformed gas increases. The amount of combustible gas is reduced. Therefore, when the cathode off-gas that has passed through the fuel cell is used as an oxidant for burning unused reformed gas in the combustion section, flammability deterioration (misfire) may occur due to a decrease in the concentration of combustible gas. . Due to the deterioration of combustibility, unburned components (CO, etc.) may remain in the combustion exhaust gas, increasing the burden on the exhaust gas treatment catalyst (purification catalyst) for removing the unburned components. To do.

  Here, in the solid oxide fuel cell system of the conventional configuration (for example, Patent Document 5), as shown in FIG. 5, as shown in FIG. The reformed gas is blown out, and the reformed gas is burned in the combustion unit 105. In this case, the flow rate, composition, and the like of the reformed gas passing through each of the solid oxide fuel cells 103 are not always constant due to the influence of load fluctuation or the like. Also, the air passing through the gaps between adjacent solid oxide fuel cells 103 is not constant in all regions. In particular, it is difficult to make it constant at the corner of the fuel cell stack.

  For this reason, for example, when increasing the fuel utilization rate to improve the power generation efficiency of a solid oxide fuel cell, the gas flow rate and gas composition change due to the influence of load fluctuations, etc. In the fuel blowing portion of the fuel cell 103, incomplete combustion may occur due to partial misfire or the like of the combustion portion.

  Therefore, as shown in FIG. 4, the combustible gas that has passed through each of the solid oxide fuel cells 3 is collected in the fuel assembly portion 20, and the combustible gas in the fuel assembly portion 20 is redistributed in the flame port 21. The structure which blows off to a combustion part in the horizontal direction is proposed. Thereby, the influence of the load fluctuation and the like in each of the solid oxide fuel cells 3 is eliminated, and partial misfire that has occurred in the conventional configuration is suppressed.

  By the way, the inventors diligently studied the ignition sequence of the combustion section at the time of starting the solid oxide fuel cell system including such a fuel assembly section, and obtained the following knowledge. In addition, although patent documents 2-4 are a thing regarding the ignition sequence of a combustion part, it thinks that it is not worth considering by the absence of the indication about said fuel assembly part 20, and suggestion.

  At the start of the solid oxide fuel cell system, air stays in the fuel assembly due to pre-purge. For this reason, when the fuel that has passed through each of the solid oxide fuel cells is supplied to the fuel assembly at startup, the fuel is diluted with the air in the fuel assembly. Then, the combustion part may be ignited in a state where the fuel concentration in the fuel assembly part is within the combustible range. In this case, the ignition characteristic of the combustion part may deteriorate, and backfire or the like to the fuel assembly part may occur.

  Therefore, a solid oxide fuel cell system according to one embodiment of the present disclosure generates power by reacting a reformer that generates reformed gas using fuel and reforming air, and the reformed gas and power generation air. A solid oxide fuel cell; a fuel collecting portion in which the gas that has passed through the solid oxide fuel cell collects; a fuel supplier that supplies fuel to the reformer; and power generation air to the solid oxide fuel cell. A first air supplier to be supplied, a second air supplier to supply reforming air to the reformer, a gas blown from the fuel assembly part, a combustion part in which power generation air is combusted, and an ignition of the combustion part An igniter to be used, and a controller for controlling the fuel supplier, the first air supplier, the second air supplier, and the igniter, and the controller, when starting the solid oxide fuel cell system, By supplying air for power generation, the fuel concentration in the fuel assembly is above a predetermined value. The fuel supply unit and the first air supply unit are controlled to control the second air supply unit so as to start the supply of reforming air or increase the supply amount. Control the igniter to ignite the gas blown out.

  According to such a configuration, it is possible to improve the ignition characteristics of the combustion part at the time of starting the solid oxide fuel cell system, and to prevent the occurrence of backfire or the like when the combustion part is ignited, as compared with the conventional case.

  In the conventional ignition sequence, the supply of reforming air is started simultaneously with the start of fuel supply (for example, the flow rate of fuel is 2.5 NL / min and the flow rate of reforming air is 2.5 NL / min. min). In this case, the fuel concentration is about 50%. Here, the total volume of the solid oxide fuel cells on the fuel supply line, the reformer, their connecting pipes, and the fuel assembly reaches several liters, and this is filled with air in the pre-purge. Has been. Therefore, the fuel flowing through the fuel supply line is diluted with the air in the fuel supply line from about 50% of the fuel concentration, so that it can become a lean fuel having a concentration of less than 25%. Therefore, when the combustion part is ignited, the fuel concentration in the fuel assembly part may fall within a combustible range (about 5% to 15 vol% in the case of city gas “13A”). In this case, in an unstable gas flow state accompanied by pulsation or the like such as when the combustion part is ignited, the flame from the flame outlet may become a backfire into the fuel assembly part.

  On the other hand, in one aspect of the present disclosure, even when air due to the pre-purge stays on the fuel supply line, particularly in the fuel assembly, the fuel concentration in the fuel assembly is in the combustible range. It can suppress that a combustion part ignites. This is due to the following reason.

  In one aspect of the present disclosure, when the solid oxide fuel cell system is started, the fuel that has passed through the solid oxide fuel cell has a high concentration (for example, the fuel flow rate is 2.5 NL / min, reforming air). The fuel concentration is 90% or more when the flow rate is 0.1 NL / min). Therefore, even when the fuel is diluted with air remaining in the fuel assembly (approximately 1 liter in volume), the fuel concentration is the upper limit of the combustible range (in the case of city gas “13A”) when the combustion portion is ignited. About 15 vol%) or more. Further, the replacement time of air in the fuel assembly calculated from the fuel flow rate and the volume of the fuel assembly is about 15 seconds. Therefore, by sufficiently delaying the ignition of the combustion section from the start of fuel supply (for example, after 30 to 60 seconds have elapsed from the start of fuel supply), the air in the fuel assembly is completely replaced with fuel. Therefore, at the time of ignition of the combustion part, the fuel concentration in the fuel assembly part can exceed the upper limit value of the combustible range. For example, the fuel concentration in the fuel assembly can be about 50% or more.

  As described above, in one aspect of the present disclosure, occurrence of backfire from the flame outlet to the fuel assembly portion can be suppressed.

  Hereinafter, embodiments of the present disclosure and first to sixth examples will be described with reference to the accompanying drawings. The following embodiment and Example 1 to Example 6 are all examples of the present disclosure. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, and the like shown here are merely examples, and do not limit the present disclosure. In addition, among the constituent elements of the embodiment and the first to sixth examples, constituent elements that are not described in the present disclosure are described as optional constituent elements. In the drawings, the same reference numerals are sometimes omitted. In addition, the drawings schematically show each component for easy understanding, and there are cases where the shape, dimensional ratio, and the like are not accurately displayed. Moreover, in a manufacturing method, the order of each process etc. can be changed as needed, and another well-known process can be added.

JP2013-12444A JP 2008-135268 A JP 2004-116934 A Japanese Patent Laid-Open No. 2008-243592 JP 2010-225454 A

(Embodiment)
[Device configuration]
FIG. 1 is a diagram illustrating an example of a solid oxide fuel cell system according to an embodiment. FIG. 1 shows a side view of the solid oxide fuel cell system 100. For convenience, it is assumed that gravity acts from “upper” to “lower”. Further, the flow of fuel and reformed gas is indicated by a thin solid line, the flow of air is indicated by a dotted line, and the flow of reformed water is indicated by a thick solid line.

  As shown in FIG. 1, the solid oxide fuel cell system 100 includes a fuel cell module 1, an accessory storage unit 2, and a controller 50.

  First, the fuel cell module 1 will be described.

  The fuel cell module 1 includes a fuel cell stack 4, a combustion unit 5, a reformer 6, an air preheater 7, an igniter 8, and a fuel assembly unit 20.

  The reformer 6 generates reformed gas using fuel and reforming air. Specifically, in the reformer 6, the fuel from the fuel path and the reforming air from the air path undergo a reforming reaction to generate a hydrogen-containing reformed gas. Examples of the reforming reaction include a steam reforming reaction, an autothermal reaction, and a partial oxidation reaction.

  The fuel is a hydrocarbon fuel containing an organic compound composed of at least carbon and hydrogen such as city gas, natural gas, and LPG mainly composed of methane.

  The fuel assembly 20 collects gas (for example, fuel or reformed gas) that has passed through the solid oxide fuel cell 3. Before starting the reforming reaction of the reformer 6 such as when the solid oxide fuel cell system 100 is started, the fuel from the gas path 16 passes through the solid oxide fuel cell 3 and after the reforming reaction starts. The reformed gas from the gas path 16 passes through the solid oxide fuel cell 3.

  As shown in FIG. 1, the fuel assembly 20 having a hollow structure is provided above the fuel cell stack 4. The interior of each solid oxide fuel cell 3 communicates with the interior of the fuel assembly 20 so that the gas collects at the fuel assembly 20.

  Further, the fuel assembly portion 20 includes a cylindrical (for example, cylindrical) side wall portion standing in the vertical direction, and several tens of flame ports 21 (for example, fuel, Round holes, which are openings for blowing out reformed gas, etc.) are formed substantially evenly in the circumferential direction.

  In the combustion unit 5, the gas blown out from the fuel assembly unit 20 and the power generation air are combusted. The igniter 8 is used to ignite the combustion unit 5. Examples of the igniter 8 include an ignition heater and a spark plug.

  Thus, in the present embodiment, when the solid oxide fuel cell system 100 is started, the fuel in the fuel assembly 20 is redistributed at the flame port 21 and blown out horizontally to the combustion unit 5. At this time, when the combustion unit 5 ignites, the fuel is burned in the combustion unit 5. Thereby, as mentioned above, the partial misfire in the combustion part 5 which generate | occur | produced with the conventional structure of FIG. 5 is suppressed.

  The combustion heat of the fuel by the combustion unit 5 is used for heating the reformer 6 provided near the upper part of the combustion unit 5 and the air preheater 7 provided above the reformer 6. For example, in the reformer 6, the fuel and the reforming air are heated, and the partial oxidation reforming reaction proceeds. When the temperature of the reformer 6 is raised to a predetermined temperature (for example, about 500 ° C.), the reformed water is supplied from the water supply unit 13 of the auxiliary equipment storage unit 2 to the fuel cell module 1. Thereby, after the reforming water is evaporated and vaporized by an evaporator (not shown), a mixed gas of fuel and water vapor is sent to the reformer 6. Then, an autothermal reaction in which the partial oxidation reforming reaction and the steam reforming reaction coexist in the reformer 6 proceeds. When the temperature of the reformer 6 is increased to a predetermined temperature (for example, about 600 ° C.), the supply of reforming air is stopped and the steam reforming reaction proceeds in the reformer 6. Thereafter, power generation of the fuel cell stack 4 starts. In addition, although the example which performs steam reforming reaction, autothermal reaction, and partial oxidation reaction as a reforming reaction was demonstrated here, it is not restricted to this. For example, only the steam reforming reaction and the autothermal reaction may be performed without performing the partial oxidation reforming reaction.

  The fuel cell stack 4 includes a plurality of solid oxide fuel cells 3. The solid oxide fuel cell 3 generates power by reacting the reformed gas and power generation air. The fuel cell stack 4 may be, for example, a flat plate stack in which members such as a plurality of flat fuel cells and interconnectors are stacked, or a plurality of cylindrical fuel cells (cell tubes) and members such as interconnectors. It may be a cylindrical stack bundled (fixed in a bundle).

  During operation of the solid oxide fuel cell system 100 (during power generation), the reformed gas exiting the reformer 6 is sufficiently mixed in the gas path 16 having a hollow structure, and then the solid oxide fuel cell 3. Are distributed evenly to the hollow regions inside the respective. As a result, the reformed gas exiting from the gas path 16 rises in the respective hollow regions of the solid oxide fuel cell 3, and hydrogen (reformed gas) necessary for the power generation reaction of the solid oxide fuel cell 3. Is supplied to the solid oxide fuel cell 3.

  On the other hand, oxygen (power generation air) necessary for the power generation reaction of the solid oxide fuel cell 3 is supplied to the fuel cell stack 4 through a route different from these. Specifically, the power generation air from the first air supply unit 11 of the auxiliary equipment storage unit 2 is pumped to the air preheater 7. In the air preheater 7, the power generation air in the air path is heated by heat exchange with the exhaust gas from the combustion unit 5. That is, the air preheater 7 constitutes a heat exchanger through which the flow path member constituting the exhaust gas path and the flow path member constituting the air path pass. Thereby, the room temperature power generation air is heated to about 600 ° C. The hot exhaust gas is cooled to about 300 ° C. The exhaust gas passes through an exhaust gas purification unit (not shown) and is discharged to the outside of the fuel cell module 1.

  The high-temperature power generation air from the air preheater 7 rises through the gaps between adjacent solid oxide fuel cells 3, and oxygen necessary for the power generation reaction of the solid oxide fuel cells 3 is solid oxide fuel cells. 3 is supplied.

  In this way, during the rise of the reformed gas and power generation air in the fuel cell stack 4, a power generation reaction occurs between hydrogen and carbon monoxide in the reformed gas and oxygen in the power generation air. And carbon dioxide gas are generated, and at the same time, an electromotive force is generated. For example, about 60% to 80% of power generation components (hydrogen and carbon monoxide) in the reformed gas are used for power generation reaction, and about 20% to 40% of unused power generation components are in the combustion section 5. Burned. Then, the combustion heat of the unused reformed gas by the combustion unit 5 is used for heating the reformer 6 provided near the upper part of the combustion unit 5 and the air preheater 7 provided above the reformer 6. Is done. In general, about 30% of oxygen in power generation air is used for power generation reaction. In addition, after the fuel cell stack 4 rises, the power generation air containing unused oxygen flows along the bottom surface of the fuel assembly portion 20 and passes through the space near the outer peripheral portion of the fuel assembly portion 20, thereby causing the combustion portion. 5 and burned in the combustion section 5.

  Next, the auxiliary machine accommodating part 2 is demonstrated.

  The auxiliary equipment housing portion 2 is provided with a fuel supply device 10, a first air supply device 11, a second air supply device 12, and a water supply device 13.

  The fuel supplier 10 supplies fuel to the reformer 6. The fuel supply device 10 is a device that adjusts the flow rate of the fuel supplied to the reformer 6, and includes, for example, a booster and a flow rate controller, but is configured with either the booster or the flow rate controller. It doesn't matter. For example, a constant displacement pump or the like is used as the booster, but is not limited thereto. For example, a flow rate control valve or the like is used as the flow rate controller, but is not limited thereto. Examples of the flow control valve include an electromagnetic valve. The fuel is supplied from a fuel supply source. The fuel supply source has a predetermined supply pressure. Examples of the fuel supply source include a fuel cylinder and a fuel infrastructure.

  The first air supplier 11 supplies power generation air to the solid oxide fuel cell 3. In the present embodiment, the power generation air from the first air supplier 11 is supplied to the solid oxide fuel cell 3 via the air preheater 7. The first air supply unit 11 is a device that adjusts the flow rate of air supplied to the solid oxide fuel cell 3 and includes, for example, a booster and a flow rate controller. For example, a blower or the like is used as the booster, but is not limited thereto. For example, a flow rate control valve or the like is used as the flow rate controller, but is not limited thereto. Examples of the flow control valve include an electromagnetic valve.

  The second air supplier 12 supplies reforming air to the reformer 6. The second air supply device 12 is a device that adjusts the flow rate of air supplied to the reformer 6, and includes, for example, a booster and a flow rate controller. For example, a blower or the like is used as the booster, but is not limited thereto. For example, a flow rate control valve or the like is used as the flow rate controller, but is not limited thereto. Examples of the flow control valve include an electromagnetic valve.

  In the above description, the example in which the first air supply device 11 and the second air supply device 12 are each configured by a booster and a flow rate controller has been described. However, the present invention is not limited to this. For example, when the reforming air and the power generation air are supplied using a single booster (for example, a blower), an air distribution path and an air distributor (for example, a distribution valve), etc., the first One of the air supplier 11 and the second air supplier 12 is constituted by a booster, and the other is constituted by an air distributor.

  The water supplier 13 supplies the reforming water to the reformer 6. The water supply device 13 is a device that adjusts the flow rate of water supplied to the reformer 6, and includes, for example, a booster and a flow rate controller. For example, a constant displacement pump or the like is used as the booster, but is not limited thereto. For example, a flow rate control valve or the like is used as the flow rate controller, but is not limited thereto. Examples of the flow control valve include an electromagnetic valve. In the case of water self-sustained operation, the reformed water may be supplied from a condensate water tank (not shown) that stores water recovered from the exhaust gas. Further, the reformed water may be supplied from a water supply source such as a water infrastructure via a water purification unit (not shown).

  The controller 50 controls the fuel supplier 10, the first air supplier 11, the second air supplier 12, and the igniter 8. Specifically, the controller 50 supplies the fuel and power generation air when starting the solid oxide fuel cell system 100 so that the fuel concentration of the fuel assembly 20 becomes a predetermined value or more. 10 and the first air supply 11 are controlled, and after the second air supply 12 is controlled so as to start the supply of reforming air or increase the supply amount, the fuel is blown out from the fuel assembly 20 to the combustion unit 5. The igniter 8 is controlled so as to ignite the gas.

  The controller 50 may have any configuration as long as it has a control function. For example, the controller 50 may include an arithmetic processing unit (not shown) and a storage unit (not shown) that stores a control program. Examples of the arithmetic processing unit include an arithmetic circuit (not shown). Examples of the arithmetic circuit include an MPU (microprocessor) and a CPU. Examples of the storage unit include a storage circuit (not shown). Examples of the memory circuit include a semiconductor memory. The controller 50 may be composed of a single controller that performs centralized control, or may be composed of a plurality of controllers that perform distributed control in cooperation with each other.

[Operation]
Hereafter, the operation | movement at the time of starting of the solid oxide fuel cell system 100 of this embodiment is demonstrated using drawing. Here, as a fuel, Japanese city gas “13A” (composition ratio of city gas “13A” is, for example, CH ₄ : 88.9%, C ₂ H ₆ : 6.8%, C ₃ H ₈ : 3.1%, C ₄ H ₁₀ : 1.2%), and a case where an ignition heater is used as the igniter 8 will be described.

  FIG. 2 is a time chart showing an example of the operation at the time of starting the solid oxide fuel cell system of the embodiment. FIG. 3 is a flowchart illustrating an example of an operation at the time of starting the solid oxide fuel cell system according to the embodiment.

  In addition, the following operation | movement is performed by execution of the control program in the controller 50. FIG.

  First, in step S1, a pre-purge of the solid oxide fuel cell system is performed. As a result, various gases remaining in the solid oxide fuel cell system 100 are exhausted outside the system. Specifically, as shown in FIG. 2, the fuel supply to the fuel cell module 1 is stopped, and a predetermined pre-purge time, power generation air and reforming air are supplied to the fuel cell module 1 at a predetermined flow rate. Is done. Note that the supply of reforming air to the fuel cell module 1 is stopped after the elapse of the pre-purge time. Power generation air is continuously supplied.

  Next, in step S2, the ignition heater is started (energization start).

  Next, in step S3, supply of fuel to the fuel cell module 1 is started. At this time, the supply of the reforming air is stopped, but as shown by a two-dot chain line in FIG. 2, a small amount of the reforming air may be supplied.

  When the flow rate of the fuel is set to a predetermined flow rate (for example, about 2.5 NL / min), the fuel concentration is 90 if the flow rate of the reforming air is a very small amount, for example, about 0.1 NL / min. % Or more. In short, if the fuel can be supplied at a sufficiently high concentration compared to the upper limit of the flammable range of fuel (about 15 vol% for city gas “13A”), the supply of reforming air is not necessarily stopped. It doesn't have to be.

  In step S4, it is determined whether a predetermined time has elapsed. If the predetermined time has not elapsed, the state is continued. When the predetermined time has elapsed, the process proceeds to the next step S5. The predetermined time in step S4 is set to a desired time between about 30 seconds and 120 seconds, for example. Note that the elapsed time in step S4 is counted by a timer or the like incorporated in the controller 50.

  Thereby, the air staying in the fuel assembly portion 20 by the pre-purge is replaced with high-concentration fuel, and the fuel concentration in the fuel assembly portion 20 is timely as shown by the one-dot chain line in FIG. It exceeds the upper limit of the flammable range of fuel (in the case of city gas “13A”, about 15 vol%).

  Next, in step S5, supply of reforming air to the fuel cell module 1 is started or the supply amount is increased. That is, when the supply of reforming air is stopped in step S3, the supply of the reforming air is started, and when a small amount of the reforming air is supplied, the reforming air is supplied. The supply amount of is increased. At this time, the reforming flow rate is set to about 2.5 NL / min, for example.

  Next, in this state, it is determined whether or not the time for ignition determination has elapsed (step S6), and it is determined whether or not the ignition of the combustion unit 5 has been detected after the main ignition determination time has elapsed. (Step S7). The elapsed time in step S6 is counted by a timer or the like incorporated in the controller 50. Moreover, the ignition of the combustion part 5 can be detected by the temperature detected by a temperature detector (not shown) provided in the reformer 6 and the like.

  When the ignition of the combustion unit 5 is detected, the energization of the ignition heater is stopped (step S8), and then the solid oxide fuel cell system 100 shifts to a predetermined power generation mode (step S9). When the ignition of the combustion unit 5 is not detected, the energization of the ignition heater is stopped (Step S10), and then the solid oxide fuel cell system 100 shifts to a predetermined abnormality processing mode (Step S11).

  As described above, this embodiment improves the ignition characteristics of the combustion unit 5 at the start-up of the solid oxide fuel cell system 100 and suppresses the occurrence of backfire or the like when the combustion unit 5 is ignited. obtain.

  In the conventional ignition sequence, the supply of reforming air is started simultaneously with the start of fuel supply (for example, the flow rate of fuel is 2.5 NL / min and the flow rate of reforming air is 2.5 NL / min. min). In this case, the fuel concentration is about 50%. Here, the total volume of the solid oxide fuel cell 3 on the fuel supply line, the reformer 6, the connecting pipes of these, and the internal volume of the fuel assembly 20 reaches several liters. The air is full. Therefore, the fuel flowing through the fuel supply line is diluted with the air in the fuel supply line from about 50% of the fuel concentration, so that it can become a lean fuel having a concentration of less than 25%. Therefore, as shown by the dotted line in FIG. 2, when the combustion part 5 is ignited, the fuel concentration in the fuel assembly part 20 may fall within the combustible range (about 5% to 15 vol% in the case of city gas “13A”). There is. In this case, in an unstable gas flow state accompanied by pulsation or the like such as when the combustion part 5 is ignited, there is a possibility that the flame from the flame port 21 becomes a backfire into the fuel assembly part 20.

  On the other hand, in the present embodiment, even if air in the pre-purge stays on the fuel supply line, particularly in the fuel assembly portion 20 due to the high concentration fuel supply in steps S3 to S4, the fuel assembly It is possible to suppress the ignition of the combustion part 5 in a state where the fuel concentration in the part 20 is within the combustible range. This is due to the following reason.

  In the present embodiment, when the solid oxide fuel cell system 100 is started, the fuel that has passed through the solid oxide fuel cell 3 has a high concentration (for example, the fuel flow rate is 2.5 NL / min, the reforming air The fuel concentration is 90% or more when the flow rate is 0.1 NL / min). Therefore, even when the fuel is diluted by air remaining in the fuel assembly 20 (volume of about 1 liter), the fuel concentration is the upper limit value of the combustible range (city gas “13A”) when the combustion unit 5 is ignited. In this case, about 15 vol%) or more can be secured. The replacement time of air in the fuel assembly 20 calculated from the fuel flow rate and the volume of the fuel assembly 20 is about 15 seconds. Therefore, by sufficiently delaying ignition of the combustion unit 5 from the start of fuel supply (for example, after 30 to 60 seconds have elapsed from the start of fuel supply), the air in the fuel assembly unit 20 is completely replaced with fuel. The Therefore, as shown by the one-dot chain line in FIG. 2, the fuel concentration in the fuel assembly portion 20 can exceed the upper limit value of the combustible range when the combustion portion 5 is ignited. For example, the fuel concentration in the fuel assembly 20 can be about 50% or more.

  As described above, in the present embodiment, it is possible to appropriately suppress the occurrence of backfire from the flame outlet 21 to the fuel collecting portion 20.

  In addition, when supply of the reforming air is started after the ignition of the combustion unit 5, in the unstable flame state of the combustion unit 5, the gas blowout flow rate from the flame port 21 increases rapidly, so that the exhaust gas has a high concentration. Of carbon monoxide (several hundred ppm or more). Further, when reforming air is not supplied (that is, when diffusion combustion is performed in the combustion unit 5 by power generation air and fuel), incomplete combustion of the combustion unit 5, a reduction in calorific value of the combustion unit 5, carbon Precipitation may occur.

  On the other hand, in this embodiment, in step S5, the supply of reforming air is started or the supply amount is increased in a timely manner before the combustion unit 5 is ignited. Therefore, the fuel concentration of the fuel assembly 20 at the time of ignition of the combustion unit 5 can be maintained at a high concentration, and the optimal combustion of the combustion unit 5 can be ensured.

(First embodiment)
The solid oxide fuel cell system 100 of the first example of the embodiment is different from the solid oxide fuel cell system 100 of the embodiment in that the controller 50 sets the fuel assembly when the solid oxide fuel cell system 100 is started. After controlling the fuel supply device 10 so as to supply the fuel assembly 20 with an amount of fuel equal to or greater than the volume of the unit 20, the second air supply unit starts the supply of reforming air or increases the supply amount. 12 is controlled.

  According to such a configuration, almost all of the air filled in the fuel assembly 20 by the pre-purge is replaced with high-concentration fuel, so that the fuel concentration in the fuel assembly 20 reaches a suitable fuel concentration that is sufficiently high. be able to.

  Since the solid oxide fuel cell system 100 of the present example is the same as the solid oxide fuel cell system 100 of the embodiment in terms of apparatus configuration and operation other than the above-described features, description thereof will be omitted.

(Second embodiment)
The solid oxide fuel cell system 100 of the second example of the embodiment is the solid oxide fuel cell system 100 of the embodiment or the first example of the embodiment. The controller 50 is a solid oxide fuel cell system. At the start-up of the system 100, the fuel supply device 10, the first air supply device 11, and the second air supply device are configured to supply power generation air and reforming air in an amount of 1.4 times or more the theoretical air ratio of the fuel. The air supplier 12 is controlled.

  When the amount of air is less than 1.4 times the theoretical air ratio of fuel, exhaust gas may contain carbon monoxide due to incomplete combustion of the combustion section 5, but in this embodiment, such a possibility is possible. Can be reduced. However, if the amount of air is too large with respect to the theoretical air ratio of the fuel (for example, an amount of air more than four times the theoretical air ratio of the fuel), there is a possibility that the flame of the combustion unit 5 is blown away.

  The solid oxide fuel cell system 100 of this example is the same as the solid oxide fuel cell system 100 of the embodiment or the first example of the embodiment in terms of the apparatus configuration and operation other than the above features. These descriptions are omitted.

(Third embodiment)
The solid oxide fuel cell system 100 of the third example of the embodiment is the same as that of the solid oxide fuel cell system 100 of any of the first and second examples of the embodiment and the embodiment. The supply amount of the quality air is set so that the gas blowing speed from the fuel collecting unit 20 to the combustion unit 5 is in the range of 0.15 m / s to 0.4 m / s. That is, the supply amount of fuel and reforming air, the opening area of the flame port 21 and the like are set so as to achieve such a gas blowing speed.

  When the gas blowing speed is less than 0.15 m / s, there is a possibility that the flame of the flame 21 formed by the ignition of the combustion unit 5 may deteriorate, and when it exceeds 0.4 m / s, Although there is a possibility that no flame is formed at the flame outlet 21, this possibility can be reduced in this embodiment.

  The solid oxide fuel cell system 100 according to the present embodiment has a device configuration and operation other than the above-described features. The solid oxide fuel according to any one of the embodiments and the first to second embodiments of the embodiment is used. Since it is the same as that of the battery system 100, description thereof is omitted.

(Fourth embodiment)
The solid oxide fuel cell system 100 of the fourth example of the embodiment is the same as the controller 50 in the solid oxide fuel cell system 100 of any of the first and third examples of the embodiment and the embodiment. The fuel supply device 10 and the second air supply device are configured so that the flow rate of the reforming air reaches the predetermined flow rate after the flow rate of the fuel reaches the predetermined flow rate when the solid oxide fuel cell system 100 is started. 12 is controlled.

  According to such a configuration, the combustion portion 5 is ignited after the fuel flow rate and the reforming air flow rate reach predetermined flow rates (for example, 2.5 NL / min), respectively. The change of the gas blowing speed of the flame port 21 at the time of ignition of the part 5 is suppressed, and the flame of the combustion part 5 can be formed stably.

  The solid oxide fuel cell system 100 according to the present embodiment is the same as that of the embodiment and the first to third embodiments of the device configuration and operation other than the above features. Since it is the same as that of the battery system 100, description thereof is omitted.

(5th Example)
The solid oxide fuel cell system 100 of the fifth example of the embodiment is the same as the controller 50 in the solid oxide fuel cell system 100 of any one of the first example to the fourth example of the embodiment and the embodiment. When the solid oxide fuel cell system 100 is started, the igniter 8 is started before the fuel is supplied.

  When the igniter 8 is, for example, an ignition heater, it takes a certain time for the temperature of the igniter 8 to reach the ignition point temperature of the fuel. Therefore, with the above configuration, the ignition of the combustion unit 5 by the igniter 8 can be performed in a timely manner. For example, it is possible to suppress ignition of the combustion part 5 in a state where the fuel concentration of the fuel assembly part 20 is within the combustible range. Further, it is possible to suppress leakage of unburned fuel to the outside of the fuel cell module 1 due to a delay in ignition of the combustion unit 5.

  The solid oxide fuel cell system 100 according to the present embodiment is the same as that of the embodiment and the first to fourth embodiments of the embodiment except for the device configuration and operation other than the above features. Since it is the same as that of the battery system 100, description thereof is omitted.

(Sixth embodiment)
The solid oxide fuel cell system 100 of the sixth example of the embodiment is the same as the solid oxide fuel cell system 100 of any of the first to fifth examples of the embodiment and the embodiment. The predetermined value is 15 vol% or more.

The fuel is, for example, city gas “13A” whose main component is methane (the composition ratio of city gas “13A” is, for example, CH ₄ : 88.9%, C ₂ H ₆ : 6.8%, C ₃ H ₈ : 3.1% , C ₄ H ₁₀ : 1.2%), as described above, the flammable range is about 5% to 15 vol%. Therefore, by setting the predetermined value of the fuel concentration to 15 vol% or more, it is possible to appropriately reduce the possibility of backfire occurring in the fuel assembly 20.

  The solid oxide fuel cell system 100 according to the present embodiment has a device configuration and operation other than the above-described features. The solid oxide fuel according to any of the embodiments and the first to fifth embodiments of the embodiment is used. Since it is the same as that of the battery system 100, description thereof is omitted.

  From the above description, many modifications and other embodiments of the present disclosure are apparent to persons skilled in the art. Accordingly, the foregoing description is to be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the disclosure. Details of the structure and / or function may be substantially changed without departing from the spirit of the present disclosure.

  One aspect of the present disclosure can improve the ignition characteristics of the combustion section when the solid oxide fuel cell system is started up, and can prevent backfire or the like from occurring when the combustion section is ignited. Therefore, one embodiment of the present disclosure can be used in, for example, a solid oxide fuel cell system.

1: Fuel cell module 2: Auxiliary equipment storage unit 3: Solid oxide fuel cell 4: Fuel cell stack 5: Combustion unit 6: Reformer 7: Air preheater 8: Igniter 10: Fuel supplier 11: No. DESCRIPTION OF SYMBOLS 1 Air supply device 12: 2nd air supply device 13: Water supply device 16: Gas path 20: Fuel assembly part 21: Flame port 50: Controller 100: Solid oxide fuel cell system

Claims (7)

A reformer that generates reformed gas using fuel and reforming air; and
A solid oxide fuel cell that generates electricity by reacting the reformed gas and power generation air; and
A fuel assembly portion where the gas that has passed through the solid oxide fuel cell collects;
A fuel supplier for supplying fuel to the reformer;
A first air supplier for supplying power generation air to the solid oxide fuel cell;
A second air supply for supplying reforming air to the reformer;
A gas blown out from the fuel assembly part, and a combustion part in which power generation air burns;
An igniter used to ignite the combustion section;
A controller for controlling the fuel supplier, the first air supplier, the second air supplier and the igniter;
The controller supplies the fuel and the power generation air when starting the solid oxide fuel cell system so that the fuel concentration in the fuel assembly becomes a predetermined value or more, and the fuel supplier and the first 1 Controlling the air supply device, controlling the second air supply device so as to start supply of the reforming air or increase the supply amount, and then ignite the gas blown from the fuel assembly portion to the combustion portion A solid oxide fuel cell system for controlling the igniter so that the igniter is controlled.   The controller controls the fuel supply unit so as to supply the fuel assembly unit with an amount of fuel equal to or larger than the volume of the fuel assembly unit when the solid oxide fuel cell system is started up, and then performs the reforming. 2. The solid oxide fuel cell system according to claim 1, wherein the second air supplier is controlled so as to start the supply of air or increase the supply amount. 3.   The controller supplies the power generation air and the reforming air in an amount of 1.4 times or more with respect to the theoretical air ratio of the fuel when the solid oxide fuel cell system is started up. The solid oxide fuel cell system according to claim 1, wherein the fuel supplier, the first air supplier, and the second air supplier are controlled.   The supply amounts of the fuel and the reforming air are set so that the gas blowing speed from the fuel assembly portion to the combustion portion is in the range of 0.15 m / s to 0.4 m / s. The solid oxide fuel cell system according to any one of claims 1 to 3.   The controller includes the fuel supply unit and the fuel supply unit so that the flow rate of the reforming air reaches a predetermined flow rate after the flow rate of the fuel reaches a predetermined flow rate when the solid oxide fuel cell system is started. The solid oxide fuel cell system according to any one of claims 1 to 5, wherein the second air supplier is controlled.   The solid oxide fuel cell system according to any one of claims 1 to 5, wherein the controller starts the igniter before supplying the fuel when the solid oxide fuel cell system is started.   The solid oxide fuel cell system according to claim 1, wherein the predetermined value of the fuel concentration is 15 vol% or more.

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