JP5114086B2 - Solid oxide fuel cell module and starting method thereof - Google Patents

Description

  The present invention relates to a solid oxide fuel cell module and a starting method thereof, and more particularly, to a structure of a solid oxide fuel cell module that enables a solid oxide fuel cell module to be started for a short time and a starting method thereof.

Fuel cells are highly efficient because they can convert chemical changes directly into electrical energy, and they do not burn fuels containing nitrogen, sulfur, etc., so emissions of air pollutants (NO _X , SO _X, etc.) There are few features that are friendly to the global environment. There are several types of fuel cells depending on the type of electrolyte. Among them, a solid oxide fuel cell (SOFC) is expected as the most efficient fuel cell.

  A solid oxide fuel cell (SOFC) uses a solid oxide such as yttria-stabilized zirconia having oxygen ion conductivity as an electrolyte and operates at a temperature of about 800 to 1000 ° C. Since the operating temperature is high, it is necessary to heat and raise the module to a temperature at which power generation is possible at startup. In the conventional SOFC, since an electric heater or the like is installed around the fuel cell module and heated, there is a problem that extra equipment and a lot of time are required for starting.

  In order to solve such a problem, in Patent Document 1 (Japanese Patent Laid-Open No. 2001-155754), a burner is built in both the anode side and the cathode side of the fuel cell module, and the module is directly used by combustion of the burner and its combustion gas. A solid electrolyte fuel cell that heats and raises the temperature has been proposed. Thereby, the fuel cell module can be heated simultaneously from the anode side and the cathode side inside the cell, and the fuel cell can be started in a short time.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2002-280053), a surface combustion burner is built in the power generation reaction chamber of the solid oxide fuel cell module, and the anode side of the fuel cell is widened by radiant heat from the red-hot burner. There has been proposed a solid oxide fuel cell that is heated by an area and eliminates an internal temperature gradient during operation. Furthermore, by utilizing the heating by the surface combustion burner also at the time of start-up, it is said that the equipment that was necessary only at the time of start-up can be eliminated.

JP 2001-155754 A JP 2002-280053 A

  However, the conventional solid oxide fuel cell module with a built-in burner has the following problems.

  For example, in a solid electrolyte fuel cell in which burners are built in the anode and cathode sides of a fuel cell module, and the module is directly heated and heated by the combustion of the burner and its combustion gas, due to the nature of burner combustion heating, local heating is used. There is a problem that it is difficult to heat uniformly over a wide area. Further, basically, the burner heating has a problem that it is difficult to delicately control the heat generation amount because the heat generation amount depends on the mixture flow rate.

  In a solid oxide fuel cell that has a built-in surface combustion burner in the power generation reaction chamber of the fuel cell module and heats the anode side of the fuel cell by radiant heat from the red-hot burner, the radiant heating from the surface combustion burner Therefore, there is an advantage that the wide range can be heated uniformly. However, as described above, since the calorific value depends on the air-fuel mixture flow rate, there is a problem that it is difficult to achieve both stable surface combustion maintenance and calorific value control.

  Therefore, an object of the present invention is to maintain a starter burner built in a solid oxide fuel cell module in a stable combustion state and to control a heat generation amount, thereby enabling a short time start of a solid oxide fuel. It is in providing a battery module and its starting method.

  The present inventors have studied in detail the combustion state of a surface combustion burner built in a closed space called a solid oxide fuel cell module. As a result, a third fluid having a predetermined flow rate is mixed in the air-fuel mixture supplied to the burner. Thus, the present invention has been completed based on the finding that it is possible to maintain both stable surface combustion and control of the calorific value, which has been difficult in the past.

In order to achieve the above object, the present invention provides a method for starting a solid oxide fuel cell module incorporating an anode burner and a cathode burner for starting a fuel cell module,
In the combustion in the anode burner and the cathode burner, in addition to supplying the first fluid as the fuel and the second fluid as the oxidant to at least one of the anode burner and the cathode burner. A starting method for a solid oxide fuel cell module is provided, wherein a third fluid different from the first and second fluids is supplied at a predetermined flow rate.

In order to achieve the above object, the present invention provides an anode burner for starting a fuel cell module according to the present invention and a method for starting a solid oxide fuel cell module incorporating a cathode burner.
A starting method for a solid oxide fuel cell module is provided, wherein an inert gas is used as the third fluid and is supplied at a flow rate ratio of 1.5 to 5 times that of the first fluid.

In order to achieve the above object, the present invention provides an anode burner for starting a fuel cell module according to the present invention and a method for starting a solid oxide fuel cell module incorporating a cathode burner.
A solid oxide fuel cell module characterized in that mist is used as the third fluid and is supplied at a flow rate of 0.68 g / min to 2.3 g / min with respect to the flow rate of 1 NL / min of the first fluid. Provide a startup method.

In order to achieve the above object, the present invention provides an anode burner for starting a fuel cell module according to the present invention and a method for starting a solid oxide fuel cell module incorporating a cathode burner.
A starting method for a solid oxide fuel cell module is provided, wherein the combustion gas composition of the anode burner is a reducing atmosphere and the combustion gas composition of the cathode burner is an oxidizing atmosphere.

In order to achieve the above object, the present invention provides an anode burner for starting a fuel cell module according to the present invention and a method for starting a solid oxide fuel cell module incorporating a cathode burner.
A solid oxide fuel cell module characterized in that an equivalence ratio of an air-fuel mixture supplied to the anode burner is 1.0 to 1.2 and an equivalence ratio of an air-fuel mixture supplied to the cathode burner is 0.4 to 0.7 Provides a starting method.

In order to achieve the above object, the present invention is a solid oxide fuel cell module incorporating an anode burner and a cathode burner for starting a fuel cell module,
In addition to a device for supplying a first fluid as a fuel and a second fluid as an oxidant to at least one of the anode burner and the cathode burner, it differs from the first and second fluids A solid oxide fuel cell module comprising a device for supplying a third fluid is provided.

In order to achieve the above object, the present invention provides the above solid oxide fuel cell module according to the present invention.
A solid oxide fuel cell module is provided in which the third fluid is an inert gas.

In order to achieve the above object, the present invention provides the above solid oxide fuel cell module according to the present invention.
There is provided a solid oxide fuel cell module characterized by having a mechanism for supplying the inert gas at a flow rate ratio of 1.5 to 5 times that of the first fluid.

In order to achieve the above object, the present invention provides the above solid oxide fuel cell module according to the present invention.
Provided is a solid oxide fuel cell module, wherein the third fluid is mist, and further comprises a spray device or an ultrasonic vibration device as means for generating the mist. A solid oxide fuel cell module is provided.

In order to achieve the above object, the present invention provides the above solid oxide fuel cell module according to the present invention.
Provided is a solid oxide fuel cell module characterized in that the mist has a mechanism to be supplied at a flow rate of 0.68 g / min to 2.3 g / min with respect to a flow rate of 1 NL / min of the first fluid. .

  According to the present invention, it is possible to keep the surface combustion burner built in the solid oxide fuel cell module in a stable combustion state and to control the amount of heat generation, and as a result, the solid oxidation that enables short-time startup. A physical fuel cell module and a starting method thereof can be provided.

  Embodiments according to the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiment taken up here.

[First embodiment of the present invention]
In the starting method of the solid oxide fuel cell module according to the present embodiment, the solid oxide fuel cell module has a built-in anode burner and cathode burner, and the anode burner and the cathode burner In combustion, in addition to supplying the first fluid as the fuel and the second fluid as the oxidant to at least one of the anode burner and the cathode burner, the first and second A third fluid different from the fluid is supplied at a predetermined flow rate. At this time, an inert gas (for example, nitrogen) is used as the third fluid, and the third fluid is supplied at a flow rate ratio of 1.5 to 5 times that of the first fluid.

(Structure of solid oxide fuel cell module)
FIG. 1 is a schematic cross-sectional view showing an example of the structure of the solid oxide fuel cell module according to the first embodiment of the present invention. In the SOFC module 100, the cell container 1, the cathode container 2, and the anode container 3 constitute an outer shell, and the outside thereof is insulated and insulated by the heat insulating material 4.

  A cathode chamber 5 is provided between the cell container 1 and the cathode container 2, and an anode chamber 6 is provided between the cell container 1 and the anode container 3. The cathode chamber 5 and the anode chamber 6 are respectively provided with a power generation air pipe 7 for supplying an oxidant (for example, air) for power generation and a power generation fuel pipe 8 for supplying fuel (for example, methane gas or hydrogen gas). It is connected. The power generation air pipe 7 and the power generation fuel pipe 8 are each provided with a valve (not shown) capable of controlling the flow rate.

  A plurality of SOFC single cells 10 are accommodated in the cell container 1, and each single cell 10 is electrically connected by a heat-resistant electric good conductor 9. At both ends of the SOFC module 100, a cathode electrode 12 and an anode electrode 14 for taking out current generated in the module are provided, and are connected to the single cell 10 via the cathode collector electrode 11 and the anode collector electrode 13, respectively. . Further, a temperature sensor (not shown) for operating temperature monitoring is installed inside the cell container 1.

  The cathode container 2 contains a cathode burner 20 for starting the fuel cell module, and the anode container 3 contains an anode burner 26 for starting. The cathode burner 20 includes a burner piping chamber 15, a mixing chamber 16, and a burner material 17, and the anode burner 26 includes a burner piping chamber 21, a mixing chamber 22, and a burner material 23. Further, it is desirable to install a surface temperature sensor 18 and a back surface temperature sensor 19 for monitoring the combustion state on the front and back of the cathode burner material 17. Further, it is desirable to install a surface temperature sensor 24 and a back surface temperature sensor 25 for monitoring the combustion state on the front and back of the anode burner material 23. The form of the cathode burner 20 and the anode burner 26 is not particularly limited, but a surface combustion burner is desirable from the advantage that a wide range can be heated uniformly. Further, as the cathode burner material 17 and the anode burner material 23, a laminate of heat-resistant metal fibers (for example, FeCrAlY alloy), porous ceramics (for example, porosity: 70 to 80%), or the like is preferably used.

  The cathode burner 20 is connected to a fuel pipe 27 for supplying fuel (first fluid, for example, methane gas) and an air pipe 28 for supplying oxidant (second fluid, for example, air). . On the other hand, the anode burner 26 is connected to a fuel pipe 29 for supplying fuel (first fluid, for example, methane gas) and an air pipe 30 for supplying oxidant (second fluid, for example, air). In addition, a nitrogen pipe 31 that supplies nitrogen gas (third fluid) that is inert to the burner combustion is connected to the air pipe 30. Each of the pipes 27 to 31 is provided with a valve (not shown) that enables flow control. Further, the connection of the nitrogen pipe 31 is not limited to the air pipe 30, and may be the fuel pipe 29 or the burner pipe chamber 21.

(Stable combustion condition of starter burner)
Next, the conditions for stably burning the starting burner using the solid oxide fuel cell module 100 shown in FIG. 1 will be described by way of example.

  A combustion test was performed on the solid oxide fuel cell module 100 in a room temperature state by igniting the start burners 22 and 26 and raising the temperature to the SOFC operating temperature (900 to 1000 ° C.). The temperature of the fuel cell module 100 was detected by a temperature sensor for operating temperature monitoring installed inside the cell container 1.

  Fuel and air were supplied from a fuel pipe 27 and an air pipe 28 to the starting cathode burner 20 built in the fuel cell module, respectively, and ignited. Similarly, fuel and air were supplied to the anode burner 26 from the fuel pipe 29 and the air pipe 30, respectively, and ignited. Methane gas was used as the burner fuel. Further, the air flow rate was adjusted so that the equivalence ratio of the air-fuel mixture supplied to the cathode burner 20 was 0.4 to 0.7 and the equivalence ratio of the air-fuel mixture supplied to the anode burner 26 was 1.0 to 1.2. The air-fuel mixture means “a mixture of fuel gas and air”, and the equivalence ratio is defined as “the fuel gas flow rate divided by the air flow rate”.

  Here, the anode of the SOFC single cell 10 is oxidized when it comes into contact with an oxidizing gas such as air and loses its electrode activity. Therefore, it is necessary to raise the temperature while maintaining the reducing atmosphere while supplying the reducing gas at startup. There is. The reason why the equivalence ratio of the air-fuel mixture supplied to the anode burner 26 is set to 1.0 to 1.2 is to make the combustion gas a reducing gas. On the other hand, since it is desirable to maintain an oxidizing atmosphere for the cathode of the SOFC single cell 10, the equivalence ratio of the air-fuel mixture supplied to the cathode burner 20 is set to 0.4 to 0.7, and the combustion gas is set to the oxidizing gas. It was.

  Whether or not the starting burner is stably combusted is determined from the difference in temperature or the change between the surface temperature sensors 18 and 24 and the back surface temperature sensors 19 and 25 installed on the burner materials 17 and 23, respectively. Specifically, in the normal (stable) surface combustion state, combustion is performed on the burner material surface, so the temperature of the burner material surface becomes higher than the temperature of the back surface of the burner material ("burner material surface temperature" ">" Burner material backside temperature "). On the other hand, as an abnormal state, the temperature of the burner material back surface is higher than the temperature of the burner material surface ("burner material surface temperature" ≤ "burner material back surface temperature"), for example, Combustion abnormality (for example, misfire) in which the temperature of the front and back surfaces of the burner material is reduced is considered.

  First, when the flow rate condition of the fuel gas (methane gas) supplied to the start burners 22 and 26 was 4 NL / min, the start burner showed a stable combustion state and a stable temperature increase of the fuel cell module. . However, since the back surface temperature sensor 25 of the anode burner material 23 exceeds about 350 ° C., it becomes difficult to maintain stable surface combustion, “surface temperature of burner material 23” ≦ “back surface temperature of burner material 23” " This was considered to be a transition from “surface combustion of the burner material 23” to “backfire to the mixing chamber 22”.

  One of the reasons for the transition from "surface combustion of burner material 23" to "backfire to mixing chamber 22" is that the temperature of the SOFC module rises during combustion of the burner built in a closed space called the SOFC module ( This is thought to be because the combustion speed of the air-fuel mixture increased as the temperature of the burner environment increased) and the balance with the flow rate of the air-fuel mixture passing through the burner material was lost.

  Therefore, when nitrogen gas (third fluid) was supplied from the nitrogen pipe 31 at a flow rate of 6 to 24 NL / min, the “surface temperature of the burner material 23”> “back surface temperature of the burner material 23” was satisfied, and it was stable. It was found that surface combustion can be maintained. Moreover, the back surface temperature of the anode burner material 23 became substantially constant at 250 to 300 ° C. Here, in the case where the flow rate condition of the fuel gas (methane gas) is 4 NL / min, the abnormal combustion considered to be flashback could not be suppressed if the flow rate condition of the nitrogen gas (third fluid) is less than 6 NL / min. Further, when the flow rate condition of the nitrogen gas (third fluid) was 25 NL / min or more, the temperature of the front and back surfaces of the anode burner material 23 began to decrease, and a combustion abnormality thought to be a partial misfire occurred.

  On the other hand, if the flow rate condition of the fuel gas (methane gas) is 4 NL / min throughout, the amount of heat generated per unit time is insufficient, and it is difficult to raise the temperature of the SOFC module to the operating temperature (900 to 1000 ° C). . Therefore, it is necessary to increase the flow rate of fuel gas (methane gas) as the temperature of the SOFC module rises. When starting from around room temperature, increasing the fuel gas flow rate (the amount of heat generated per unit time) from the beginning increases the possibility of damage to the SOFC module due to a large thermal shock to the SOFC module. It is preferable to set the flow rate condition of the fuel gas at the start of the temperature increase to be low (for example, about 1/3 of the maximum flow rate condition).

  As the temperature of the SOFC module increased, the flow rate of methane gas (fuel gas, first fluid) increased, and the flow rate of nitrogen gas (third fluid) required to maintain stable surface combustion also increased. . Specifically, when the flow rate condition of methane gas is 6 NL / min, 10 NL / min, and 12 NL / min, the flow rate conditions of nitrogen gas necessary for maintaining stable surface combustion are 9 -39 NL / min, 15-50 NL / min, and 18-60 NL / min.

  Further, when the combustion gas of the anode burner was analyzed in a state where the anode burner 26 maintained stable surface combustion, it was confirmed that it was a reducing gas.

  After the temperature is raised to a temperature at which the SOFC module 100 can be operated (900 to 1000 ° C.), power can be generated by supplying air from the power generation air pipe 7 and fuel from the power generation fuel pipe 8. After the power generation in the SOFC module 100 is started, the combustion of the anode burner 26 and the cathode burner 20 may be stopped.

  From the above combustion test, in order to maintain stable surface combustion of the starting burner, an inert gas (for example, nitrogen) for combustion is used as the third fluid, and the fuel gas (first fluid) is used. It has been found that it is preferable to supply at a flow rate ratio of 1.5 to 5 times. More preferably, they are 1.5 times or more and 4.5 times or less, More preferably, they are 2 times or more and 4 times or less.

  The third fluid may be any gas that is inert to combustion in the start-up burner, and other inert gases such as argon and helium may be used in addition to the nitrogen described above. Further, since the inert gas for combustion is supplied as the third fluid, the equivalence ratio in the air-fuel mixture is not affected. As a result, the combustion gas of the anode burner and the combustion gas of the cathode burner are respectively desired reducing gases. And can be maintained in an oxidizing gas. Furthermore, since the inert gas for combustion is supplied as the third fluid, the calorific value of the burner and the flow rate of the air-fuel mixture passing through the burner material can be controlled independently.

[Second Embodiment of the Present Invention]
In the starting method of the solid oxide fuel cell module according to the present embodiment, the solid oxide fuel cell module has a built-in anode burner and cathode burner, and the anode burner and the cathode burner In combustion, in addition to supplying the first fluid as the fuel and the second fluid as the oxidant to at least one of the anode burner and the cathode burner, the first and second A third fluid different from the fluid is supplied at a predetermined flow rate. At this time, a mist (for example, a mist of pure water) is used as the third fluid, and is supplied at a flow rate of 0.68 g / min to 2.3 g / min with respect to the flow rate of 1 NL / min of the first fluid. Features.

(Structure of solid oxide fuel cell module)
FIG. 2 is a schematic cross-sectional view showing an example of the structure of a solid oxide fuel cell module according to the second embodiment of the present invention. Parts having the same structure as those of the SOFC module according to the first embodiment are denoted by the same symbols as those in FIG. 1, and detailed description thereof is omitted.

  Connected to the anode burner 26 of the SOFC module 200 are a fuel pipe 29 for supplying fuel (first fluid, for example, methane gas) and an air pipe 30 for supplying oxidant (second fluid, for example, air). In addition, a water supply pipe 41 for supplying mist (third fluid) that is inactive with respect to combustion of the burner is connected to the air pipe 30 via a mist generator 42. The mist generator 42 is not particularly limited as long as mist can be supplied to the air-fuel mixture as a result, but a spray device, an ultrasonic vibration device, or the like can be preferably used. The water supply pipe 41 is provided with a valve (not shown) that enables flow rate control. Further, the connection between the water supply pipe 41 and the mist generator 42 is not limited to the air pipe 30 and may be the fuel pipe 29.

  Moreover, the mist used as the third fluid only needs to supply a liquid that is inactive with respect to combustion in the start burner. For example, pure water can be suitably used. In SOFC power generation (steady operation), since water is often added to the fuel, there is no particular problem even if mist that is water is mixed with the fuel or air supplied to the start-up burner.

(Stable combustion condition of starter burner)
Next, the conditions for stably burning the start burner using the SOFC module 200 shown in FIG. 2 will be described by way of example. As in the case of the first embodiment described above, a combustion test is performed in which the start-up burners 22 and 26 are ignited to raise the temperature to the SOFC operating temperature (900 to 1000 ° C.) with respect to the SOFC module 200 in the room temperature state. went.

  When the temperature of the fuel gas (methane gas) supplied to the start-up burners 22 and 26 was 4 NL / min and the temperature was raised, the back surface temperature sensor 25 of the anode burner material 23 exceeded about 350 ° C. The surface temperature of 23 ”≦“ the back surface temperature of the burner material 23 ”, and abnormal combustion considered to be“ backfire to the mixing chamber 22 ”occurred.

  Therefore, when pure water is supplied from the water supply pipe 41 to the mist generator 42 and the generated mist (third fluid) is mixed with air (second fluid), the “surface temperature of the burner material 23”> “ It was found that the temperature of the back surface of the burner material 23 was "stable and stable surface combustion could be maintained. This is presumably because the mixed mist vaporized in the mixing chamber 22 and functioned as water vapor inert to combustion. The flow rate condition of the mist at this time was 0.68 g / min to 2.3 g / min with respect to the flow rate 1 NL / min of methane gas (first fluid). Moreover, the back surface temperature of the anode burner material 23 became substantially constant at 250 to 300 ° C. When the mist flow rate was less than 0.68 g / min with respect to the methane gas flow rate of 1 NL / min, the abnormal combustion considered to be flashback could not be suppressed. Further, when the mist flow rate condition was larger than 2.3 g / min, the temperature of the front and back surfaces of the anode burner material 23 began to decrease, and a combustion abnormality thought to be a partial misfire occurred.

  Next, when the flow rate of methane gas was increased as the temperature of the SOFC module 200 increased, the flow rate condition of mist necessary for maintaining stable surface combustion was 0.68 with respect to the flow rate of 1 NL / min of methane gas. It was g / min or more and 2.3 g / min or less. Further, when the anode burner 26 maintained stable surface combustion, the combustion gas of the anode burner was analyzed, and it was confirmed that it was a reducing gas.

  After the temperature is raised to a temperature (900 to 1000 ° C.) at which the SOFC module 200 can be operated, power can be generated by supplying air from the power generation air pipe 7 and fuel from the power generation fuel pipe 8. After the power generation in the SOFC module 200 is started, the combustion of the anode burner 26 and the cathode burner 20 may be stopped.

  From the above combustion test, in order to maintain stable surface combustion of the starting burner, mist is used as the third fluid, and the flow rate of fuel gas (first fluid) is 0.68 g / min with respect to 1 NL / min. It has been found that it is preferable to supply at a flow rate of 2.3 g / min or less. More preferably, it is 0.68 g / min or more and 2.0 g / min or less, and further preferably 0.90 g / min or more and 1.8 g / min or less.

[Third embodiment of the present invention]
(Structure of solid oxide fuel cell module)
FIG. 3 is a schematic cross-sectional view showing an example of the structure of a solid oxide fuel cell module according to the third embodiment of the present invention. Parts having the same structure as those of the SOFC module according to the first embodiment are denoted by the same symbols as those in FIG. 1, and detailed description thereof is omitted.

  The cathode burner 20 of the SOFC module 300 is connected to a fuel pipe 27 that supplies fuel (first fluid, for example, methane gas) and an air pipe 28 that supplies oxidant (second fluid, for example, air). In addition, a nitrogen pipe 51 that supplies nitrogen gas (third fluid) that is inert to the burner combustion is connected to the air pipe 28. The nitrogen pipe 51 is provided with a valve (not shown) that enables flow rate control. Further, the connection of the nitrogen pipe 51 is not limited to the air pipe 28 but may be the fuel pipe 27 or the burner pipe chamber 15.

(Stable combustion condition of starter burner)
Next, the conditions for stably burning the start burner using the SOFC module 300 shown in FIG. 3 will be described by way of example. As in the case of the first embodiment described above, a combustion test is performed in which the start-up burners 22 and 26 are ignited to raise the temperature to the SOFC operating temperature (900 to 1000 ° C.) with respect to the SOFC module 300 at room temperature. went.

  When the temperature of the fuel gas (methane gas) supplied to the starting burners 22 and 26 was 4 NL / min and the temperature was raised, the temperature of the front and back surfaces of the cathode burner material 17 was “the surface temperature of the burner material 17” ≦ “burner The temperature of the back surface of the material 17 was reached, and abnormal combustion thought to be “backfire to the mixing chamber 16” occurred. The cause of abnormal combustion in the cathode burner 20 is not clear, but the thermal insulation in the vicinity of the cathode burner 20 of the SOFC module 300 is higher than that of the SOFC modules 100 and 200, so the burning rate in the cathode burner 20 is high. This was thought to be because the flow rate of the supplied air-fuel mixture became higher.

  Therefore, when nitrogen gas (third fluid) is supplied from the nitrogen pipe 51 under the same flow rate conditions as in the first embodiment described above, “the surface temperature of the burner material 17”> “burner material 17 It was found that stable surface combustion can be maintained. In addition, when the flow rate of methane gas was increased as the temperature of the SOFC module 300 increased, the mist flow rate necessary to maintain stable surface combustion was also 1.5 times to 5 times the methane gas flow rate. It was the following. In addition, when the cathode burner 20 maintained stable surface combustion, the combustion gas of the cathode burner was analyzed and confirmed to be an oxidizing gas.

  After raising the temperature to a temperature at which the SOFC module 300 can be operated (900 to 1000 ° C.), power can be generated by supplying air from the power generation air pipe 7 and fuel from the power generation fuel pipe 8. After the power generation in the SOFC module 300 is started, the combustion of the cathode burner 20 and the anode burner 26 may be stopped.

  From the above combustion test, in order to maintain stable surface combustion of the starting burner, an inert gas (for example, nitrogen) for combustion is used as the third fluid, and the fuel gas (first fluid) is used. It has been found that it is preferable to supply at a flow rate ratio of 1.5 to 5 times. More preferably, they are 1.5 times or more and 4.5 times or less, More preferably, they are 2 times or more and 4 times or less.

[Effect of the embodiment]
According to the above embodiment of the present invention, the following effects can be obtained.
(1) In addition to supplying the first fluid as the fuel and the second fluid as the oxidizer to the burner for starting the SOFC, a third fluid that is inert to combustion is supplied at a predetermined flow rate. Since the supply ratio does not affect the equivalence ratio in the air-fuel mixture, the combustion gas of the anode burner and the combustion gas of the cathode burner can be easily maintained at the desired reducing gas and oxidizing gas, respectively.
(2) In addition to supplying the first fluid as the fuel and the second fluid as the oxidizer to the burner for starting SOFC, a third fluid that is inert to combustion is supplied at a predetermined flow rate. Since supplying, the calorific value (fuel flow rate) of the burner and the flow rate of the air-fuel mixture can be controlled independently.
(3) Since the calorific value (fuel flow rate) of the starting burner and the flow rate of the air-fuel mixture passing through the burner material can be controlled independently, optimal heating can be performed while maintaining stable combustion of the burner, As a result, the SOFC module can be started in a shorter time than before.

  The effects of the present invention will be described below based on examples, but the present invention is not limited to these examples.

(Examples 1-3 and Comparative Examples 1-2)
As SOFC modules for the start-up test, the SOFC modules 100 (see FIG. 1), 200 (see FIG. 2), and 300 (see FIG. 3) of the above-described embodiment were prepared. Using each SOFC module, a start-up test was performed in which the temperature was raised from room temperature to the operating temperature (900 to 1000 ° C.), and the time required for start-up was measured. In the temperature increase test, in order to prevent damage to the SOFC module due to thermal shock at the time of temperature increase or an excessive temperature gradient, the temperature difference between the plurality of temperature sensors installed in the cell container 1 is about 100 ° C. or less. As described above, the flow rate of the methane gas (first fluid) supplied to the starting burners 22 and 26 was controlled.

  A start-up test using the SOFC module 100 and heated according to the first embodiment described above was taken as Example 1. A start-up test using the SOFC module 200 and heated in accordance with the second embodiment described above was taken as Example 2. A start-up test using the SOFC module 300 and heated according to the third embodiment described above was taken as Example 3.

  On the other hand, a start-up test in which the temperature was raised without supplying the third fluid using the SOFC module 100 was set as Comparative Example 1. Further, a start-up test using the SOFC module 300 and raising the temperature without supplying the third fluid was referred to as Comparative Example 2.

  As a result of the start-up test, Examples 1 to 3 were able to stably raise the temperature to the operating temperature (900 to 1000 ° C.) in a short time of 10 to 12 hours. This is considered to be an effect of the present invention that “the heating value of the starting burner and the flow rate of the air-fuel mixture can be controlled independently and optimum heating can be performed while maintaining stable combustion of the burner”. In contrast, Comparative Examples 1 and 2 required a long time of 35 to 40 hours. Since the third fluid is not supplied to the starting burner, the burner is likely to generate abnormal combustion that is considered to be a backfire, while the flow rate of the air-fuel mixture is increased in order to ensure the flow rate of the air-fuel mixture passing through the burner material. Since it was easy to form an excessive temperature gradient due to excessive heat generation, it was necessary to perform burner combustion intermittently. For this reason, constant heating / heating could not be performed, and a long time was required.

It is a cross-sectional schematic diagram which shows an example of the structure of the solid oxide fuel cell module which concerns on the 1st Embodiment of this invention. It is a cross-sectional schematic diagram which shows an example of the structure of the solid oxide fuel cell module which concerns on the 2nd Embodiment of this invention. It is a cross-sectional schematic diagram which shows an example of the structure of the solid oxide fuel cell module which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

100, 200, 300 ... Solid oxide fuel cell module,
DESCRIPTION OF SYMBOLS 1 ... Cell container, 2 ... Cathode container, 3 ... Anode container, 4 ... Thermal insulation,
5 ... Cathode chamber, 6 ... Anode chamber, 7 ... Air piping for power generation, 8 ... Fuel piping for power generation,
9 ... good electrical conductor, 10 ... single cell,
11 ... Cathode collector electrode, 12 ... Cathode electrode, 13 ... Anode collector electrode, 14 ... Anode electrode,
15,21 ... Burner piping chamber, 16,22 ... Mixing chamber, 17,23 ... Burner material,
18, 24 ... surface temperature sensor, 19, 25 ... back surface temperature sensor,
20 ... Cathode burner, 26 ... Anode burner,
27, 29 ... fuel piping, 28, 30 ... air piping,
31, 51 ... Nitrogen piping, 41 ... Water supply pipe, 42 ... Mist generator.

Claims (11)

A method for starting a solid oxide fuel cell module including an anode burner and a cathode burner for starting a fuel cell module,
The anode burner and the cathode burner are surface combustion burners;
In the combustion in the anode burner and the cathode burner, in addition to supplying the first fluid as the fuel and the second fluid as the oxidant to at least one of the anode burner and the cathode burner. , wherein the first and the second to the fluid and different Ri combustion by supplying an inert third fluid at a predetermined flow rate, and the flow rate of the first fluid, the first and the second A starting method for a solid oxide fuel cell module, wherein the flow rate of an air-fuel mixture containing fluid is controlled independently . In the starting method of the solid oxide fuel cell module according to claim 1,
A method for starting a solid oxide fuel cell module, wherein an inert gas is used as the third fluid, and the first fluid is supplied at a flow rate ratio of 1.5 to 5 times. In the starting method of the solid oxide fuel cell module according to claim 1,
A solid oxide fuel cell module characterized in that mist is used as the third fluid and is supplied at a flow rate of 0.68 g / min to 2.3 g / min with respect to the flow rate of 1 NL / min of the first fluid. starting method. In the starting method of the solid oxide fuel cell module according to any one of claims 1 to 3,
A starting method for a solid oxide fuel cell module, wherein the combustion gas composition of the anode burner is a reducing atmosphere, and the combustion gas composition of the cathode burner is an oxidizing atmosphere. In the starting method of the solid oxide fuel cell module according to claim 4,
A solid oxide fuel cell module characterized in that an equivalence ratio of an air-fuel mixture supplied to the anode burner is 1.0 to 1.2 and an equivalence ratio of an air-fuel mixture supplied to the cathode burner is 0.4 to 0.7 How to start. A solid oxide fuel cell module including an anode burner and a cathode burner for starting a fuel cell module,
The anode burner and the cathode burner are surface combustion burners;
In addition to a device for supplying a first fluid as a fuel and a second fluid as an oxidant to at least one of the anode burner and the cathode burner, the first burner is different from the first and second fluids. A device that supplies a third fluid that is inert to combustion and independently controls the flow rate of the first fluid and the flow rate of the air-fuel mixture containing the first and second fluids. A solid oxide fuel cell module comprising: The solid oxide fuel cell module according to claim 6, wherein
The solid oxide fuel cell module, wherein the third fluid is an inert gas. The solid oxide fuel cell module according to claim 7,
A solid oxide fuel cell module comprising a mechanism in which the inert gas is supplied to the first fluid at a flow rate ratio of 1.5 to 5 times. The solid oxide fuel cell module according to claim 6, wherein
The solid oxide fuel cell module, wherein the third fluid is mist. The solid oxide fuel cell module according to claim 9, wherein
A solid oxide fuel cell module comprising a spray device or an ultrasonic vibration device as means for generating the mist. The solid oxide fuel cell module according to any one of claims 9 to 10,
A solid oxide fuel cell module having a mechanism in which the mist is supplied at a flow rate of 0.68 g / min to 2.3 g / min with respect to a flow rate of 1 NL / min of the first fluid.

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