JP6284814B2 - Method, apparatus and program for evaluating soundness of fuel gas flow path of solid oxide fuel cell - Google Patents

Description

  The present invention relates to a soundness evaluation of a fuel gas flow path of a solid oxide fuel cell. More specifically, in the present invention, the structure of the fuel gas flow path of the solid oxide fuel cell is a structure that can appropriately contribute the fuel gas supplied to the fuel electrode including the fuel gas flow path to the electrode reaction. The present invention relates to a method, an apparatus, and a program suitable for evaluating whether or not there is a problem.

  Patent Document 1 describes a method for evaluating the soundness of a solid oxide fuel cell. Specifically, in a solid oxide fuel cell having a cell stack in which power generation cells and separators are alternately stacked and supplying a reaction gas to each of the power generation cells to cause a power generation reaction, While supplying the reaction gas to each, the test stack is applied to both ends in the stacking direction of the cell stack, the impedance between each separator is measured, and the impedance characteristics are compared with each other, so that the cell stack is healthy. I try to evaluate sex.

  In Patent Document 1, when there is a performance defect or malfunction in any of the single cell units by this evaluation method, it is caused by the uniformity of the supply flow rate of the reaction gas supplied to each power generation cell. It is described that it is possible to specify whether it is due to the uniformity of the internal resistance between the separators.

JP 2005-108674 A

  In the development of a solid oxide fuel cell, it may be necessary to evaluate the soundness other than the above. For example, it may be necessary to evaluate the soundness of the gas flow path, that is, whether the structure of the gas flow path is a structure that can appropriately contribute to the electrode reaction of the gas supplied to the gas flow path. . However, the method for evaluating the soundness of the gas flow path has not yet been established.

  Therefore, an object of the present invention is to provide a method, an apparatus, and a program for evaluating the soundness of a fuel gas flow path of a solid oxide fuel cell.

  In general, fuel gas obtained by externally reforming methane or the like is supplied to the fuel electrode including the fuel gas flow path of the solid oxide fuel cell. Here, the fuel gas obtained by externally reforming methane or the like contains almost no methane. Therefore, conventionally, a gas containing almost no methane has been generally supplied to the fuel electrode including the fuel gas flow path of the solid oxide fuel cell.

  However, as a result of intensive studies by the inventors of the present application, the methane-containing gas containing water vapor is directly supplied to the fuel electrode including the fuel gas flow path of the solid oxide fuel cell, and the inlet of the fuel gas flow path (fuel gas In the fuel electrode including the fuel gas flow path, by accurately grasping the amount of gas components (that is, the amount of various components constituting the gas) at the introduction part) and the outlet of the fuel gas flow path (fuel gas discharge part) It is possible to grasp the reaction state of methane, and accordingly, the soundness of the fuel gas flow path (that is, the structure of the fuel gas flow path appropriately supplies the fuel gas supplied to the fuel electrode including the fuel gas flow path). It has been found that it is possible to evaluate whether or not the structure can contribute to the reaction, and various studies have been repeated to complete the present invention.

  That is, the method for evaluating the soundness of the fuel gas flow path of the solid oxide fuel cell according to the present invention analyzes a methane-containing gas whose component amount is unknown and substantially free of water vapor using a gas chromatograph. Water vapor is mixed into a reaction gas, and the reaction gas is supplied to the fuel gas introduction part of the fuel electrode including the fuel gas flow path of the solid oxide fuel cell to discharge the fuel gas from the fuel electrode including the fuel gas flow path. The off-gas is discharged from the head, the water vapor is removed from the off-gas to make an analytical off-gas, the component amount of the analytical off-gas is analyzed by gas chromatograph, Calculates the amount of components, and performs mass balance calculation that takes into account chemical reactions that occur at the fuel electrode including the fuel gas flow path, using the component amounts of the reaction gas and the off-gas component for analysis. The Rukoto, calculates the component amounts of off-gas, using the ingredient amounts and components of the off-gas of the reaction gas, so that to grasp the reaction conditions of the methane in the fuel electrode including a fuel gas passage.

  Further, the method for evaluating the soundness of the fuel gas flow path of the solid oxide fuel cell of the present invention comprises mixing a methane-containing gas having a known component amount and substantially free of water vapor and water vapor to form a reaction gas, The reaction gas is supplied to the fuel gas introduction part of the fuel electrode including the fuel gas flow path of the solid oxide fuel cell, and the off gas is discharged from the fuel gas discharge part of the fuel electrode including the fuel gas flow path. Is removed as an analysis off-gas, and the amount of component of the off-gas for analysis is analyzed by gas chromatography, and the amount of the component of the reaction gas is calculated from the amount of the methane-containing gas and the water vapor content of the reaction gas. The off-gas component amount is calculated by performing mass balance calculation considering the chemical reaction occurring in the fuel electrode including the fuel gas flow path using the component amount and the off-gas component amount for analysis. Using the ingredient amounts and components of the off-gas of the scan, so that to grasp the reaction conditions of the methane in the fuel electrode including a fuel gas passage.

  Next, the soundness evaluation apparatus for a fuel gas flow path of a solid oxide fuel cell according to the present invention is obtained by gas chromatographic analysis of a methane-containing gas whose component amount is unknown and substantially free of water vapor. A fuel electrode including a fuel gas passage by supplying a component gas content gas, a reaction gas obtained by mixing a methane-containing gas and water vapor to a fuel gas introduction portion of a fuel electrode including a fuel gas passage of a solid oxide fuel cell Means for reading from the storage device the component amount of the analytical off gas obtained by gas chromatographic analysis of the analytical off gas from which the water vapor has been removed from the off gas discharged from the fuel gas discharge section, and the water vapor content of the reaction gas Calculate the component amount of the reaction gas from the component amount of the methane-containing gas and the water vapor content of the reaction gas, and use the component amount of the reaction gas and the component amount of the off-gas for analysis to calculate the fuel gas flow. The off-gas component amount is calculated by performing a mass balance calculation in consideration of the chemical reaction occurring at the fuel electrode including the fuel gas, and the fuel gas flow path is included using the reaction gas component amount and the off-gas component amount. And means for obtaining the reaction status of methane at the fuel electrode.

In addition, the device for evaluating the soundness of the fuel gas flow path of the solid oxide fuel cell according to the present invention includes a component amount of a methane-containing gas having a known component amount and substantially free of water vapor, and mixing the methane-containing gas and water vapor. The supplied reaction gas is supplied to the fuel gas introduction part of the fuel electrode including the fuel gas flow path of the solid oxide fuel cell, and water vapor is discharged from the off-gas discharged from the fuel gas discharge part of the fuel electrode including the fuel gas flow path. Means for reading the analysis offgas component amount obtained by gas chromatographic analysis of the removed analysis offgas and the water vapor content of the reaction gas from the storage device, the component amount of the methane containing gas and the water vapor of the reaction gas Calculate the amount of the reaction gas component from the content, and use the reaction gas component amount and the analysis off-gas component amount to take into account the chemical reaction that occurs in the fuel electrode including the fuel gas flow path. Means for calculating the off-gas component amount by calculating the off-gas component amount, and using the reaction gas component amount and the off-gas component amount to determine the reaction state of methane at the fuel electrode including the fuel gas flow path. I have it.

  Next, the program for evaluating the integrity of the fuel gas flow path of the solid oxide fuel cell according to the present invention is a methane obtained by gas chromatographic analysis of a methane-containing gas whose component amount is unknown and substantially free of water vapor. A fuel electrode including a fuel gas passage by supplying a component gas content gas, a reaction gas obtained by mixing a methane-containing gas and water vapor to a fuel gas introduction portion of a fuel electrode including a fuel gas passage of a solid oxide fuel cell Means for reading from the storage device the component amount of the off gas for analysis obtained by gas chromatographic analysis of the off gas for analysis obtained by removing the water vapor from the off gas discharged from the fuel gas discharge unit, and the water vapor content of the reaction gas, In addition, the component amount of the reaction gas is calculated from the component amount of the methane-containing gas and the water vapor content of the reaction gas, and the component amount of the reaction gas and the component amount of the off-gas for analysis are used. By performing mass balance calculation taking into account the chemical reaction occurring in the fuel electrode including the fuel gas flow path, the amount of off-gas component is calculated, and the amount of component of the reaction gas and the amount of off-gas component are used to calculate the fuel gas. The computer functions as a means for obtaining the reaction state of methane at the fuel electrode including the flow path.

The program for evaluating the soundness of the fuel gas flow path of the solid oxide fuel cell according to the present invention includes a component amount of a methane-containing gas having a known component amount and substantially free of water vapor, and mixing methane-containing gas and water vapor. The supplied reaction gas is supplied to the fuel gas introduction part of the fuel electrode including the fuel gas flow path of the solid oxide fuel cell, and water vapor is discharged from the off-gas discharged from the fuel gas discharge part of the fuel electrode including the fuel gas flow path. Means for reading the analysis off-gas component amount obtained by gas chromatographic analysis of the removed analysis off- gas and the water vapor content of the reaction gas from the storage device, and the methane-containing gas component amount and the reaction gas Calculate the reaction gas component amount from the water vapor content, and consider the chemical reaction that occurs at the fuel electrode including the fuel gas flow path using the reaction gas component amount and the analysis off gas component amount. By calculating the mass balance calculation, the off-gas component amount is calculated, and the reaction state of methane in the fuel electrode including the fuel gas flow path is obtained by using the reaction gas component amount and the off-gas component amount. As a computer function.

  According to the soundness evaluation method, apparatus and program for the fuel gas flow path of the solid oxide fuel cell of the present invention, the soundness of the fuel gas flow path of the solid oxide fuel cell can be evaluated. Therefore, the evaluation of whether or not the structure of the fuel gas flow path of the solid oxide fuel cell is a structure that can appropriately contribute to the electrode reaction of the fuel gas supplied to the fuel electrode including the fuel gas flow path. It becomes possible to carry out appropriately. Therefore, it becomes possible to design a fuel gas flow path based on the evaluation result of the present invention, and can greatly contribute to the development of a solid oxide fuel cell.

It is a flowchart explaining an example of embodiment of the soundness evaluation method of this invention. It is a functional block diagram of the soundness evaluation apparatus implement | achieved by the said program in the case of implementing the soundness evaluation method of embodiment using the soundness evaluation program. It is a schematic block diagram of the analysis data acquisition apparatus of embodiment. It is a drawing alternative photograph which shows the single cell used in the Example, The left side is a fuel electrode side cell, and the right side is an air electrode side cell. In an Example, it is a drawing alternative photograph which shows the state which has arrange | positioned the gold | metal | money for sealing and the nickel net | network on the metal jig by the side of a fuel electrode. In an Example, it is a drawing alternative photograph which shows the state which set the single cell on the metal jig by the side of a fuel electrode. In an Example, it is a drawing alternative photograph which shows the state which has arrange | positioned the alumina felt and the platinum net | network (already with the air electrode paste) on the metal jig by the side of an air electrode. In an Example, it is a drawing alternative photograph which shows the state which mounted the metal jig by the side of the fuel electrode which set the single cell on the metal mount. In an Example, it is a drawing alternative photograph which shows the final setup state. In an Example, it is a figure which shows the state of arrangement | positioning of a voltage line and a current line. It is the structure schematic of the analysis data acquisition apparatus used in the Example. It is the figure which plotted the methane unreacted rate with respect to the non-methane reforming rate about the various conditions examined in the Example. It is the figure which plotted the methane unreacted rate with respect to the fuel utilization rate about the various conditions examined in the Example.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  In the following description, the solid oxide fuel cell may be referred to as “SOFC”.

  FIG. 1 to FIG. 3 show an example of embodiments of the soundness evaluation method, apparatus, and program for the SOFC fuel gas flow path of the present invention.

  In the method for evaluating the soundness of the fuel gas flow path of the SOFC of the present invention, a methane-containing gas whose component amount is unknown and substantially free of water vapor is analyzed by gas chromatography (S1), and the methane-containing gas and water vapor are mixed. The reaction gas is supplied to the fuel gas introduction part of the fuel electrode including the SOFC fuel gas flow path, and the off gas is discharged from the fuel gas discharge part of the fuel electrode including the fuel gas flow path. (S3) Water vapor is removed from the off-gas to obtain an analysis off-gas (S4), and the amount of components of the off-gas for analysis is analyzed by gas chromatography (S5). The amount of component of the working gas is calculated (S6), and the mass considering the chemical reaction occurring in the fuel electrode including the fuel gas flow path using the component amount of the reaction gas and the component amount of the off-gas for analysis is calculated. By performing lance calculation, the off-gas component amount is calculated (S7), and the reaction state of methane at the fuel electrode including the fuel gas channel is grasped using the reaction gas component amount and off-gas component amount. (S8).

  In addition, the soundness evaluation device for the fuel gas flow path of the SOFC of the present invention includes the component amount of the methane-containing gas obtained by gas chromatographic analysis of the methane-containing gas whose component amount is unknown and substantially free of water vapor, From the off gas discharged from the fuel gas discharge section of the fuel electrode including the fuel gas flow path by supplying the reaction gas mixed with the methane-containing gas and water vapor to the fuel gas introduction section of the fuel electrode including the SOFC fuel gas flow path Means for reading from the storage device (data reading unit 11a) the component amount of the analytical off gas obtained by gas chromatographic analysis of the analytical off gas from which water vapor has been removed, and the water vapor content of the reaction gas; Calculate the component amount of the reaction gas from the component amount and the water vapor content of the reaction gas, and use the component amount of the reaction gas and the component amount of the off-gas for analysis to calculate the fuel gas flow path. A fuel including a fuel gas flow path is calculated by calculating a mass balance in consideration of a chemical reaction occurring in the fuel electrode including the component gas and calculating the off-gas component amount and the off-gas component amount. And means (calculation unit 11b) for obtaining the reaction state of methane at the pole.

  Furthermore, the soundness evaluation program for the fuel gas flow path of the SOFC of the present invention includes a component amount of a methane-containing gas obtained by gas chromatographic analysis of a methane-containing gas whose component amount is unknown and substantially free of water vapor, From the off gas discharged from the fuel gas discharge section of the fuel electrode including the fuel gas flow path by supplying the reaction gas mixed with the methane-containing gas and water vapor to the fuel gas introduction section of the fuel electrode including the SOFC fuel gas flow path Means (data reading unit 11a) for reading the component amount of the analysis off gas obtained by gas chromatographic analysis of the analysis off gas from which water vapor has been removed, and the water vapor content of the reaction gas from the storage device, and the methane containing gas The amount of the reaction gas component is calculated from the amount of the component and the water vapor content of the reaction gas, and the amount of the reaction gas component and the amount of the off-gas component for analysis are used. By performing mass balance calculation taking into account the chemical reaction occurring in the fuel electrode including the fuel gas flow path, the amount of off-gas component is calculated, and the amount of component of the reaction gas and the amount of off-gas component are used to calculate the fuel gas. The computer (10) is caused to function as means (calculation unit 11b) for obtaining the reaction state of methane at the fuel electrode including the flow path.

  In performing the soundness evaluation of the fuel gas flow path of the SOFC of the present invention, first, the processes from S1 to S5 are performed.

  The processing from S1 to S5 is performed, for example, by the analysis data acquisition device shown in FIG. A methane-containing gas is supplied from the methane-containing gas supply device 22 toward the fuel gas introduction portion 21a of the SOFC 21. In the gas flow path from the methane-containing gas supply device 22 to the fuel gas introduction part 21a, a part of the methane-containing gas is subjected to GC (gas chromatograph) analysis. Thereafter, water vapor is supplied to the methane-containing gas by the water vapor supply device 23, and the methane-containing gas and the water vapor are mixed to form a reaction gas. This reaction gas is supplied to the fuel gas introduction part 21a. The reaction gas supplied to the fuel gas introduction part 21a flows through the fuel electrode including the fuel gas flow path of the SOFC 21 that is heated and controlled to an appropriate operating temperature in the electric furnace 25, and is then turned off from the fuel gas discharge part 21b. As discharged. The off-gas is removed from the water vapor by the water vapor removing device 26 to become an off-gas for analysis, and is used for GC analysis. Thereafter, the analysis off-gas is discharged out of the system after passing through, for example, a detoxifying device (not shown).

The methane-containing gas supplied from the methane-containing gas supply device 22 toward the fuel gas introduction part 21a of the SOFC 21 is a methane-containing gas whose component amount is unknown and substantially free of water vapor. That is, it is a methane-containing gas containing methane and a gas other than methane and substantially free of water vapor. Gases other than methane include, for example, carbon monoxide (CO), carbon dioxide (CO ₂ ), hydrogen (H ₂ ), nitrogen (N ₂ ), etc., supplied to the fuel electrode including the SOFC fuel gas flow path. One or more types of gases that are allowed (in other words, gases that do not oxidize the fuel gas flow path constituent material and the fuel electrode constituent material). “Substantially free of water vapor” means that it does not contain an amount of water vapor that can interfere with gas chromatographic analysis. Is acceptable.

  The gas chromatographic analysis of the methane-containing gas is appropriately performed using an apparatus capable of quantitative analysis of the components of the methane-containing gas (specifically, gas components constituting the methane-containing gas). Here, in order to improve the compactness of the analytical data acquisition device, it is preferable to use a small gas chromatograph analyzer. Examples of such a gas chromatograph analysis device include, but are not limited to, a micro gas chromatograph device such as M200 manufactured by Agilent or Micro GC490 manufactured by GL Science.

  The water vapor supply device 23 can be used without any particular limitation as long as it is a device capable of continuously supplying a certain amount of water vapor to the methane-containing gas. Examples of such a device include a bubbler type humidifier, but are not limited thereto.

  A dew point meter 24 is provided downstream of the water vapor supply device 23. Thereby, the amount of water vapor in the reaction gas can be constantly monitored. However, when the supply amount (flow rate) of methane-containing gas and the supply amount (flow rate) of water vapor are clear, the supply amount (flow rate) of methane-containing gas and the supply amount of water vapor (without the dew point meter 24) ( From the flow rate), the water vapor content of the reaction gas can be determined. Moreover, you may make it obtain | require the water vapor | steam content rate of reaction gas using apparatuses other than the dew point meter 24. FIG.

  The reaction gas generated by mixing the methane-containing gas and water vapor is introduced from the fuel gas introduction part 21a, and after participating in the chemical reaction in the process of passing through the fuel electrode including the fuel gas flow path, the fuel gas discharge part 21 b is discharged as off-gas and introduced into the water vapor removing device 26.

  The water vapor removing device 26 can be used without any particular limitation as long as it is a device that can remove water vapor from the off-gas discharged from the fuel gas discharge portion 21b. Examples of such an apparatus include a cooler and the like, but are not limited thereto.

  The water vapor removal from the off gas by the water vapor removing device 26 may be performed at a level at which the analysis off gas obtained by removing the water vapor from the off gas does not substantially contain water vapor. Note that “substantially free of water vapor” means that, as defined above, it does not contain an amount of water vapor that can interfere with gas chromatographic analysis, and does not interfere with gas chromatographic analysis. Water vapor content at is acceptable.

  The gas chromatographic analysis of the off gas for analysis is appropriately performed using an apparatus capable of quantitative analysis of the components of the off gas for analysis (specifically, gas components constituting the off gas for analysis). Here, in order to improve the compactness of the analytical data acquisition device, it is preferable to use a small gas chromatograph analyzer. Examples of such a gas chromatograph analysis device include, but are not limited to, a micro gas chromatograph device such as M200 manufactured by Agilent or Micro GC490 manufactured by GL Science.

  In addition, you may make it implement the gas chromatograph analysis of methane containing gas, and the gas chromatograph analysis of the off gas for analysis using a common gas chromatograph analyzer. Thereby, the compact product of the analysis data acquisition device can be improved. If this common gas chromatograph analyzer is a small gas chromatograph analyzer (for example, a micro gas chromatograph such as M200 manufactured by Agilent, or a micro GC 490 manufactured by GL Science), the compactness of the analytical data acquisition device can be further increased. Can be improved.

  Next, the process after S6 is performed using the data acquired by the process of S1-S5, ie, the component amount of the methane-containing gas, the component amount of the off-gas for analysis, and the water vapor content of the reaction gas.

  Here, the processing after S6 in the soundness evaluation of the SOFC fuel gas flow path of the present invention can be executed by the SOFC fuel gas flow path soundness evaluation apparatus of the present invention.

  And the process after S6 in the soundness evaluation method for the fuel gas flow path of the SOFC of the present invention and the soundness evaluation device for the fuel gas flow path of the SOFC that executes these processes are the fuel gas flow path of the SOFC of the present invention. It can also be realized by executing the soundness evaluation program on the computer.

  In the present embodiment, when the SOFC fuel gas flow path soundness evaluation program is executed on a computer, the processing after S6 of the SOFC fuel gas flow path soundness evaluation method is executed, and S6 The case where the soundness evaluation apparatus of the SOFC fuel gas flow path for executing the subsequent processes is realized will be described.

  FIG. 2 shows the overall configuration of a computer 10 for executing the SOFC fuel gas flow path soundness evaluation program 17 (which is also the SOFC fuel gas flow path soundness evaluation apparatus 10 in this embodiment). . The computer 10 includes a control unit 11, a storage unit 12, an input unit 13, a display unit 14, and a memory 15, and is connected to each other by a signal line such as a bus. In addition, a data server 16 as a storage device is connected to the computer 10 by a signal line such as a bus, and transmission / reception (ie, input / output) of signals such as data and control commands is mutually performed via the signal line. Done.

  The control unit 11 performs control and calculation of the entire computer 10 by the soundness evaluation program 17 of the SOFC fuel gas flow path stored in the storage unit 12, and is, for example, a CPU (Central Processing Unit). .

  The storage unit 12 is a device that can store at least data and programs, and is, for example, a hard disk.

  The memory 15 serves as a memory space that is a work area when the control unit 11 executes various controls and operations, and is, for example, a RAM (abbreviation of Random Access Memory).

  The input unit 13 is an interface for giving at least an operator's command to the control unit 11, and is, for example, a keyboard.

  The display unit 14 performs drawing / display of characters, graphics, and the like under the control of the control unit 11 and is, for example, a display.

  In the present embodiment, the component amount of the methane-containing gas, the component amount of the off-gas for analysis, and the water vapor content rate of the reaction gas obtained by the processing of S1 to S5 described above are stored in the data server 16 as the calculation database 18 ( Saved). The data acquired by the processing of S1 to S5 may be recorded in the calculation database 18 in the data server 16 by the operator after being stored in an appropriate recording medium, for example, The data may be automatically recorded in the calculation database 18 in the data server 16 via a wireless or wired communication means.

  Further, the control unit 11 of the computer 10 executes the SOFC fuel gas flow path soundness evaluation program 17 to read the data acquired by the processing of S1 to S5 from the data server 16 as a storage device. A data reading unit 11a that performs the above and an arithmetic unit 11b that performs calculations using these data are configured.

  When the soundness evaluation program 17 is executed, first, the data reading unit 11a configured in the control unit 11 of the computer 10 performs the component amount of the methane-containing gas, the component amount of the analysis off-gas, and the water vapor content rate of the reaction gas. Read the data. Specifically, the data reading unit 11a acquires the component amount of the methane-containing gas, the component amount of the off-gas for analysis, and the component amount that are recorded in the calculation database 18 that is acquired by the processing of S1 to S5 and stored in the data server 16. Data on the water vapor content of the reaction gas is read from the data server 16.

  Then, the data reading unit 11 a causes the memory 15 to record the read methane-containing gas component amount, analytical off-gas component amount, and reaction gas water vapor content.

  Subsequently, in the calculation unit 11b of the control unit 11, the component amount of the reaction gas is calculated from the component amount of the methane-containing gas and the water vapor content of the reaction gas (S6).

  Next, a mass balance calculation is performed in consideration of a chemical reaction occurring in the fuel electrode including the fuel gas flow path, using the calculated reaction gas component amount and analysis off gas component amount, and the off gas component amount is calculated. (In other words, the amount of the component considering the water vapor content removed by the water vapor removing device 26) is calculated (S7).

Here, examples of the chemical reaction occurring in the fuel electrode including the fuel gas channel include (1) power generation reaction, (2) leak reaction, (3) shift reaction, and (4) reforming reaction.
(1) H ₂ + 1 / 2O ₂ = H ₂ O
(2) H ₂ + 1 / 2O ₂ = H ₂ O
(3) H ₂ + CO ₂ = CO + H ₂ O
(4) CH ₄ + H ₂ O = 3H ₂ + CO

In addition, the equilibrium constants K _{1 to} K ₄ of the chemical reactions (1) to (4) are as follows. In the formula, p (gas constituent molecule) means a partial pressure of the gas constituent molecule in the gas. For example, p (H ₂ ) means the partial pressure of H _{2 in} the gas.
K ₁ = p (H ₂ O) / {p (H ₂ ) × p (O ₂ ) ^1/2 }
K ₂ = p (H ₂ O) / {p (H ₂ ) × p (O ₂ ) ^1/2 }
K ₃ = {p (CO) × p (H ₂ O)} / {p (H ₂ ) × p (CO ₂ )}
K ₄ = {p (H ₂ ) ³ × p (CO)} / {p (CH ₄ ) × p (H ₂ O)}

The mass balance calculation is performed by the following procedure, for example. First, the component amounts of the reaction gas are as follows.
<Reaction gas component amount>
CH ₄ A [mol]
H ₂ B [mol]
CO ₂ C [mol]
CO D [mol]
N ₂ E [mol]
H ₂ O F [mol]
Total A + B + C + D + E + F [mol]

Here, among the component amounts of the reaction gas, the component amounts of CH ₄ , H ₂ , CO ₂ , CO, and N ₂ can be obtained by gas chromatographic analysis. The component amount of H 2 _O, can be obtained by the processing of S6. Therefore, the numerical values of A to F become clear.

Next, (1) the conversion amount of H _{2 in} the power generation reaction is a [mol], (2) the conversion amount of H _{2 in} the leak reaction is b [mol], and (3) the conversion amount of CO _{2 in} the shift reaction. Is c [mol], and (4) the conversion amount of CH ₄ in the reforming reaction is d [mol]. In this case, the amount of off-gas components is as follows.
<Amount of off-gas components>
CH ₄ A-d [mol]
_{H 2 B-a-b-} c + 3d [mol]
CO ₂ C-c [mol]
CO D + c + d [mol]
N ₂ E + 2b [mol]
_{H 2 O F + a + b} + c-d [mol]
Total A + B + C + D + E + F + 2b + 2d [mol]

Note that O ₂ is not detected because both the reaction gas and the off-gas are in a reducing atmosphere, but N ₂ enters the fuel electrode including the fuel gas channel from the outside due to the leak reaction of (2). It can be increased by an amount corresponding to oxygen (b / 2 min). That is, when the _N 2 / _{O 2} in dry air and 4, (b / 2) × 4 = 2b [mol] content of _{N 2} may increase.

Here, among the off-gas component amounts, the component amounts of CH ₄ , H ₂ , CO ₂ , CO, and N ₂ can be obtained by gas chromatographic analysis. Assuming that these values are X ₁ , X ₂ , X ₃ , X ₄ and X ₅ , respectively, at least one of a, b, c and d is used as a parameter from the numerical values of A to E which are clarified as described above. The following five equations are obtained.
Ad = X ₁
B−a−b−c + 3d = X ₂
Cc = X ₃
D + c + d = X ₄
E + 2b = X ₅

Further, using off-gas CH ₄ , H ₂ , CO ₂ , CO, N ₂ component amounts X ₁ , X ₂ , X ₃ , X ₄ and X ₅ obtained from gas chromatographic analysis and the working pressure P of SOFC, The partial pressure of each component of the off gas can be expressed as follows.
p (CH ₄ ) = P × X ₁ / (A + B + C + D + E + F + 2b + 2d)
p (H ₂ ) = P × X ₂ / (A + B + C + D + E + F + 2b + 2d)
p (CO ₂ ) = P × X ₃ / (A + B + C + D + E + F + 2b + 2d)
p (CO) = P × X ₄ / (A + B + C + D + E + F + 2b + 2d)
p (N ₂ ) = P × X ₅ / (A + B + C + D + E + F + 2b + 2d)
p (H ₂ O) = P × (F + a + b + c−d) / (A + B + C + D + E + F + 2b + 2d)
Since the values of the equilibrium constants K _{1 to} K ₄ become clear from the operating temperature of the SOFC, four more equations are derived from the relationship between these partial pressures and the equilibrium constants K _{1 to} K ₄ .

From these four equations and the above five equations, (1) H ₂ conversion amount a [mol] in power generation reaction, (2) H ₂ conversion amount b [mol] in leak reaction, (3) shift reaction The conversion amount c [mol] of CO ₂ in (4), and the conversion amount d [mol] of CH ₄ in the reforming reaction can be obtained. Thereby, the component amount (F + a + b + cd [mol]) of H ₂ O in the off gas becomes clear, and all the component amounts of the off gas become clear.

Finally, the reaction state of methane at the fuel electrode including the fuel gas flow path is obtained using the calculated component amounts of the reaction gas and off-gas components (S8). Specifically, for example, the methane partial pressure of the reaction gas is calculated from the calculated component amount of the reaction gas, the methane partial pressure of the off gas is calculated from the calculated component amount of the off gas, and the methane of the reaction gas is calculated. The methane unreacted rate [%] at the fuel electrode including the fuel gas flow path is obtained from the partial pressure and the methane partial pressure of the off-gas by the following formula to obtain the reaction state of methane at the fuel electrode including the fuel gas flow path. It is done. In the following equation, α is the methane partial pressure of the reaction gas, and β is the off-gas methane partial pressure.
[Methane unreacted rate] = β / α × 100

  The methane unreacted rate [%] in the fuel electrode including the fuel gas flow path obtained by the above processing is determined by the structure of the fuel gas flow path (fuel gas introduction portion 21a to fuel gas discharge portion 21b) of the SOFC 21. This is an index for determining whether or not the fuel gas supplied to the fuel electrode including the flow channel can appropriately contribute to the electrode reaction. However, it is assumed that no methane reforming catalyst is installed in the fuel gas flow path. That is, the higher the methane unreacted rate, the more difficult the structure of the fuel gas channel contributes to the electrode reaction of the fuel gas supplied to the fuel electrode including the fuel gas channel. It can be said that the structure is easy to pass through without undergoing a reaction). On the contrary, it can be said that the lower the methane unreacted rate, the easier the structure of the fuel gas flow channel is to easily contribute the fuel gas supplied to the fuel electrode including the fuel gas flow channel to the electrode reaction. In addition, when the methane unreacted rate is high, the Nernstruss increases and the cell stack performance decreases. Therefore, by evaluating the soundness according to the present invention, it is possible to evaluate the quality of the cell stack when SOFC cells are stacked.

  The calculation of the reaction state of methane in the fuel electrode including the fuel gas flow path using the calculated reaction gas component amount and off-gas component amount is not limited to the above method. As long as the reaction state of methane at the fuel electrode including the road can be grasped, it may be appropriately changed. For example, not the methane unreacted rate at the fuel electrode including the fuel gas channel, but the methane reaction rate at the fuel electrode including the fuel gas channel may be obtained. In this case, it can be said that the higher the methane reaction rate, the more easily the structure of the fuel gas channel easily contributes to the electrode reaction of the fuel gas supplied to the fuel electrode including the fuel gas channel. On the contrary, it can be said that the lower the methane reaction rate, the more the structure of the fuel gas channel is less likely to appropriately contribute to the electrode reaction of the fuel gas supplied to the fuel electrode including the fuel gas channel.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, when a methane-containing gas having a known component amount and substantially free of water vapor is used, gas chromatographic analysis (S1) of the methane-containing gas may be omitted from the above-described soundness evaluation method. Moreover, it is also possible to omit the previous GC analysis in the above-described analysis data acquisition apparatus. Note that when the component amount of the methane-containing gas is known, for example, when the methane-containing gas is substantially composed only of methane, or when a methane-containing gas that has been analyzed in advance is used, it is sufficient. The case where each gas component which comprises methane containing gas is supplied with the calibrated mass flow controller is mentioned.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

1. Cell Specification In this example, a flat SOFC manufactured by NexTech Materials (NTM) was used. Table 1 shows the specifications of the SOFC single cell and metal jig. In Table 1, the electrode area is a measured value. The electrode thickness is a value obtained by measurement from a secondary electron image photograph.

  In this example, an SOFC single cell having an electrolyte support structure was used. Specifically, the air electrode material and the fuel electrode material shown in Table 1 were each applied to the electrolyte plate and then fired. A photograph of the single cell is shown in FIG. In FIG. 4, the left is the fuel electrode side cell, and the right is the air electrode side cell.

2. Cell setup Cell setup was performed according to the following procedure.

  First, a pressed nickel wire (φ1 mm) was embedded in the fuel gas flow path of the metal jig on the fuel electrode side. And the gold | metal | money for a seal | sticker (0.2 mm thickness, made from Tanaka Kikinzoku) was arrange | positioned on the outer side on this metal jig, and the nickel net | network (0.2 mm thickness 60 mesh, product made from Niraco) was arrange | positioned inside. A fuel electrode paste (Ni, manufactured by NTM) was applied with a sponge to the front and back surfaces of the nickel net. FIG. 5 shows a state where the sealing gold and the nickel net are arranged on the metal jig on the fuel electrode side.

  Next, the fuel electrode of the SOFC single cell was stacked so as to be disposed immediately above the nickel net. At that time, the fuel electrode paste was applied to the surface of the fuel electrode of the SOFC single cell with a sponge. FIG. 6 shows a state where the SOFC single cell is set on the metal jig on the fuel electrode side. The upper surface of the SOFC single cell is an air electrode.

Next, alumina felt was placed on the outside on the metal jig on the air electrode side, and three platinum meshes (80 mesh, made by Tanaka Kikinzoku) were placed on the inside. The alumina slurry was sufficiently immersed in the alumina felt. The surface and the rear surface of the platinum gauze was air electrode paste _{(La 0.80 Sr 0.20 MnO 3-} d, manufactured by NTM) was applied. FIG. 7 shows a state in which alumina felt and platinum net (air electrode paste applied) are arranged on a metal jig on the air electrode side.

  Next, three sheets of fine flex 1300 paper (Nichias Co., Ltd.) having a thickness of 3 mm were stacked on a metal stand, and a metal jig on the fuel electrode side (FIG. 5) on which a SOFC single cell was set was placed thereon (FIG. 5). FIG. 8).

  Finally, apply the air electrode paste to the air electrode of the SOFC single cell in the state shown in FIG. 8 for 100 microns or more, and place the metal jig on the air electrode side directly above the air electrode of the SOFC single cell. After stacking as described, a weight (12 kg) was placed. The final setup state is shown in FIG. The weight of the metal jig is 1.3 kg.

  The cell set up by the above method is referred to as “setup A” in the following description.

  Further, in the above cell setup method, the thickness of the sealing gold is changed to 0.5 mm (made by Tanaka Kikinzoku), and the pressed nickel wire is not embedded in the fuel gas flow path of the metal jig on the fuel electrode side. Instead, a nickel net (0.3 mm thickness 30 mesh, manufactured by NTM) was arranged inside the metal jig on the fuel electrode side, and a weight of 4 kg was also prepared. In the following description, this is referred to as “setup B”.

  In addition, as shown in FIG. 10, the voltage line is protected by an alumina tube having an outer diameter of 1.2 mm and a hole diameter of 0.8 mm on a pipe having an outer diameter of 1/4 inch and a wall thickness of 1 mm used for introducing a metal jig gas. Two platinum wires (diameter 0.3 mm) were passed through (one was a spare), and the fuel electrode side was connected to the nickel net and the air electrode side was connected to the platinum net. At that time, it was confirmed by a tester that the metal jig and the platinum wire as the voltage wire were not in contact. Moreover, the piping of the metal jig was used as a current line.

  The test was performed using the analytical data acquisition apparatus shown in FIG. 11 and setting the temperature of the electric furnace 25 to 825 ° C. A methane-containing gas from a gas mixer having a function as the methane-containing gas supply device 22 is humidified by a bubbler 23 to be a reaction gas, and this is used as an inlet for a fuel electrode including a fuel gas flow path (fuel gas introduction portion 21a). Introduced. The amount of water vapor supplied to the methane-containing gas by the bubbler 23 was constantly monitored by installing a dew point meter 24 (HyroFlex 3 manufactured by Rotronic) downstream of the bubbler. The off-gas discharged from the outlet of the fuel electrode (fuel gas discharge part 21b) including the fuel gas flow path is sufficiently removed from the water vapor by the cooler 26 to be an analysis off-gas, and a micro gas chromatograph (Setup A is manufactured by Agilent) M200 and setup B were analyzed by GL Science Micro GC490). After the analysis, the off gas for analysis was discharged out of the system after passing through the abatement device.

As will be described later, the test was performed under the same conditions, the first time with OCV (open circuit voltage) and the second time with a current density of 200 mA / cm ² (current value 6.4 A). The gas chromatographic analysis was performed only once. Since the gas supply conditions for the second time were the same as those for the first time, the component amount of the methane-containing gas was handled as known, and gas chromatographic analysis was omitted.

In addition, air was supplied from the gas mixer toward the inlet (air introduction part) on the air electrode side of the SOFC, and was discharged from the outlet (air discharge part) on the air electrode side. The air after being discharged from the outlet on the air electrode side was discharged out of the system after the O ₂ content was analyzed by the O ₂ sensor.

  For the setup A, the test was performed under the conditions shown in Tables 2 to 4 below.

In test condition 1 shown in Table 2, when S / C (steam carbon ratio) = 2.5, tests of 8 conditions were carried out with different Rf (fuel reforming rate) and Uf (fuel utilization rate). did. Moreover, the test of these 8 conditions was implemented by OCV (open circuit voltage) 1st time and current density 200mA / cm < ² > (current value 6.4A) ^2nd time.

In test condition 2 shown in Table 3, for S / C (steam carbon ratio) = 3.0, Rf (fuel reforming rate) and Uf (fuel utilization rate) were varied, and eight conditions were tested. Moreover, the test of these 8 conditions was implemented by OCV (open circuit voltage) 1st time and current density 200mA / cm < ² > (current value 6.4A) ^2nd time.

In test condition 3 shown in Table 4, with respect to S / C (steam carbon ratio) = 2.5 and 3.0, Uf (fuel utilization rate) not examined in test conditions 1 and 2 was 4 to 5 respectively. A condition test was performed. In addition, for S / C (steam carbon ratio) = 2.0, tests were performed under six conditions with different Uf (fuel utilization ratio). Similar to the test conditions 1 and 2, these tests were performed at the first time with OCV (open circuit voltage) and at the second time with a current density of 200 mA / cm ² (current value 6.4 A).

  In Tables 2 to 4, UO2 is an oxygen utilization rate, and An (or An gas) is a reaction gas. Ca (or Ca gas) is a cathode gas. The dew point temperature is a set target value, and the temperature of the bubbler was adjusted so that the dew point meter (HyroFlex 3 manufactured by Rotronic Co.) reached the dew point temperature. The amount of water vapor was calculated from the measured dew point temperature using humidity calculation software (http://www.vaisala.co.jp/jp/support/HumidityCalculator/Pages/default.aspx).

  Next, Table 5 shows the test conditions of the setup B.

Regarding the setup B, tests of 5 conditions were carried out with different Rf (fuel reforming rate) and Uf (fuel utilization rate) for S / C (steam carbon ratio) = 2.5 and 2.6. Moreover, the test of these 5 conditions was implemented by OCV (open circuit voltage) 1st time, and current density 200mA / cm < ² > (current value 6.4A) ^2nd time. For some conditions, the test was also performed at a current density of 100 mA / cm ² (current value 3.2 A).

  The result of plotting the methane unreacted rate against the non-methane reforming rate is shown in FIG.

Since no significant difference was observed between the OCV condition and the 200 mA / cm ² condition, it was revealed that the present invention can be implemented under the OCV condition.

  Moreover, the S / C = 2.5 and Uf 6.2% conditions of the setup B did not show a great difference in the methane unreacted rate from the S / C = 2.5 and Uf 20% of the setup A. The Uf 6.2% condition has a lower fuel gas utilization rate than the Uf 20% condition. Nevertheless, since there was no significant difference in the methane unreacted rate, the setup B has a higher soundness of the fuel gas flow path than the setup A, that is, the structure of the fuel gas flow path It has been clarified that the fuel gas supplied to the fuel electrode including the gas flow path can easily contribute to the electrode reaction. Also, from this result, the thickness of the sealing gold, which is the difference between setup A and setup B, and the material used for the fuel gas flow path of the metal jig on the fuel electrode side (pressed nickel wire, nickel mesh) It was considered that at least one of them could contribute to improving the soundness of the fuel gas flow path.

  Next, the result of plotting the methane unreacted rate against the fuel utilization rate is shown in FIG.

It was confirmed that as the fuel utilization rate increased, the methane unreacted rate also decreased. In addition, when compared at the same fuel utilization rate, it became clear that setup B had a lower methane unreacted rate than setup A. Also from this result, the setup B has higher fuel gas channel soundness than the setup A, that is, the structure of the fuel gas channel is suitable for the fuel gas supplied to the fuel electrode including the fuel gas channel. It was revealed that the structure easily contributes to the electrode reaction.

10 Computer 11a Reading unit 11b Calculation unit 21 Solid oxide fuel cell 21a Fuel gas introduction unit 21b Fuel gas discharge unit

Claims (6)

Analyzing a methane-containing gas whose component amount is unknown and substantially free of water vapor by gas chromatography,
Mixing the methane-containing gas and water vapor into a reaction gas,
Supplying the reaction gas to a fuel gas introduction part of a fuel electrode including a fuel gas flow path of a solid oxide fuel cell to discharge off-gas from a fuel gas discharge part of the fuel electrode including the fuel gas flow path;
Water vapor is removed from the off-gas to make an off-gas for analysis,
Gas chromatographic analysis of the component amount of the off-gas for analysis,
Calculate the component amount of the reaction gas from the component amount of the methane-containing gas and the water vapor content of the reaction gas,
By performing a mass balance calculation that takes into account a chemical reaction occurring in the fuel electrode including the fuel gas flow path using the component amount of the reaction gas and the component amount of the analysis off gas, the component amount of the off gas is calculated. Calculate
A fuel gas for a solid oxide fuel cell, characterized in that a reaction state of methane in a fuel electrode including the fuel gas flow path is grasped by using a component amount of the reaction gas and a component amount of the off gas. A method for evaluating the integrity of the flow path. Mixing a methane-containing gas with a known component amount and substantially free of water vapor and water vapor to form a reaction gas,
Supplying the reaction gas to a fuel gas introduction part of a fuel electrode including a fuel gas flow path of a solid oxide fuel cell to discharge off-gas from a fuel gas discharge part of the fuel electrode including the fuel gas flow path;
Water vapor is removed from the off-gas to make an off-gas for analysis,
Gas chromatographic analysis of the component amount of the off-gas for analysis,
Calculate the component amount of the reaction gas from the component amount of the methane-containing gas and the water vapor content of the reaction gas,
By performing a mass balance calculation that takes into account a chemical reaction occurring in the fuel electrode including the fuel gas flow path using the component amount of the reaction gas and the component amount of the analysis off gas, the component amount of the off gas is calculated. Calculate
A fuel gas for a solid oxide fuel cell, characterized in that a reaction state of methane in a fuel electrode including the fuel gas flow path is grasped by using a component amount of the reaction gas and a component amount of the off gas. A method for evaluating the integrity of the flow path. The component amount of the methane-containing gas obtained by gas chromatographic analysis of a methane-containing gas whose component amount is unknown and substantially free of water vapor, and the reaction gas mixed with the methane-containing gas and water vapor is in solid oxide form Gas chromatograph for analyzing off-gas from which off-gas is supplied to fuel gas introduction part of fuel electrode including fuel gas flow path of fuel cell and discharged from fuel gas discharge part of fuel electrode including fuel gas flow path Means for reading from the storage device the component amount of the off gas for analysis obtained by analysis and the water vapor content of the reaction gas;
The fuel gas is calculated by calculating the component amount of the reaction gas from the component amount of the methane-containing gas and the water vapor content of the reaction gas, and using the component amount of the reaction gas and the component amount of the off-gas for analysis. By performing a mass balance calculation taking into account a chemical reaction occurring in the fuel electrode including the flow path, the component amount of the off gas is calculated, and the component amount of the reaction gas and the component amount of the off gas are used. An apparatus for evaluating the soundness of a fuel gas flow path of a solid oxide fuel cell, comprising: means for obtaining a reaction state of methane in a fuel electrode including the fuel gas flow path. The component amount of methane-containing gas component amount does not include and water vapor substantially known, the reaction gas mixed with the methane-containing gas and water vapor in the fuel electrode including a fuel gas flow passage of the solid oxide fuel cell Components of the off gas for analysis obtained by gas chromatographic analysis of the off gas for analysis obtained by removing water vapor from the off gas supplied to the fuel gas introduction unit and discharged from the fuel gas discharge unit of the fuel electrode including the fuel gas flow path Means for reading the amount and the water vapor content of the reaction gas from a storage device;
The fuel gas is calculated by calculating the component amount of the reaction gas from the component amount of the methane-containing gas and the water vapor content of the reaction gas, and using the component amount of the reaction gas and the component amount of the off-gas for analysis. By performing a mass balance calculation taking into account a chemical reaction occurring in the fuel electrode including the flow path, the component amount of the off gas is calculated, and the component amount of the reaction gas and the component amount of the off gas are used. An apparatus for evaluating the soundness of a fuel gas flow path of a solid oxide fuel cell, comprising: means for obtaining a reaction state of methane in a fuel electrode including the fuel gas flow path . The component amount of the methane-containing gas obtained by gas chromatographic analysis of a methane-containing gas whose component amount is unknown and substantially free of water vapor, and the reaction gas mixed with the methane-containing gas and water vapor is in solid oxide form Gas chromatograph for analyzing off-gas from which off-gas is supplied to fuel gas introduction part of fuel electrode including fuel gas flow path of fuel cell and discharged from fuel gas discharge part of fuel electrode including fuel gas flow path Means for reading from the storage device the component amount of the analytical off-gas obtained by analysis and the water vapor content of the reaction gas; and
The fuel gas is calculated by calculating the component amount of the reaction gas from the component amount of the methane-containing gas and the water vapor content of the reaction gas, and using the component amount of the reaction gas and the component amount of the off-gas for analysis. By performing a mass balance calculation taking into account a chemical reaction occurring in the fuel electrode including the flow path, the component amount of the off gas is calculated, and the component amount of the reaction gas and the component amount of the off gas are used. A program for evaluating the soundness of a fuel gas flow path of a solid oxide fuel cell, wherein the computer functions as a means for obtaining a reaction state of methane in a fuel electrode including the fuel gas flow path. The component amount of methane-containing gas component amount does not include and water vapor substantially known, the reaction gas mixed with the methane-containing gas and water vapor in the fuel electrode including a fuel gas flow passage of the solid oxide fuel cell Components of the off gas for analysis obtained by gas chromatographic analysis of the off gas for analysis obtained by removing water vapor from the off gas supplied to the fuel gas introduction unit and discharged from the fuel gas discharge unit of the fuel electrode including the fuel gas flow path Means for reading the amount and the water vapor content of the reaction gas from a storage device; and
The fuel gas is calculated by calculating the component amount of the reaction gas from the component amount of the methane-containing gas and the water vapor content of the reaction gas, and using the component amount of the reaction gas and the component amount of the off-gas for analysis. By performing a mass balance calculation taking into account a chemical reaction occurring in the fuel electrode including the flow path, the component amount of the off gas is calculated, and the component amount of the reaction gas and the component amount of the off gas are used. A program for evaluating the soundness of a fuel gas flow path of a solid oxide fuel cell, wherein the computer functions as a means for obtaining a reaction state of methane in a fuel electrode including the fuel gas flow path.

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