JP2019200887A - Cell evaluation system and method - Google Patents

Abstract

To make it possible to accurately and simply detect a crack generated in a single cell of a solid oxide fuel cell, even when the crack is micro-order minute one.SOLUTION: A single cell S1 is clamped and held between an air electrode side holder 11 and a fuel electrode side holder 12 via a seal member S2 so as to form a first gas introduction space E1 and a second gas introduction space E2 taking the single cell S1 as a boundary. Air gas is introduced from an air gas supply/discharge unit 20 to the air gas introduction space E1 so as to make differential pressure so that back pressure of the fuel gas introduction space E2 is higher than back pressure of the air gas introduction space E1; and fuel gas is introduced from a fuel gas supply/discharge unit 30 to the fuel gas introduction space E2. A control unit 60 determines that a crack is generated in the single cell S1 when a signal showing detection of fuel gas from gas discharged from the air gas supply/discharge unit 20 is input from a gas detection unit 40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cell evaluation system and method for evaluating a damage process during power generation of a single cell used in a solid oxide fuel cell (SOFC).

  2. Description of the Related Art Conventionally, a solid oxide fuel cell (hereinafter simply referred to as “SOFC”), which is one type of fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen, is known.

  SOFC is generally a stack of a plurality of single cells each having a fuel electrode that transmits fuel gas on one surface of the solid electrolyte and an air electrode that transmits air gas on the other surface. The fuel cell is operated at an operating temperature of, for example, about 700 to 1000 ° C. while supplying air gas (gas containing oxygen) to the air electrode while supplying fuel gas to the electrode. By operating in this way, an electromotive force is generated between the pair of electrodes as the oxide ions move from the air electrode side to the fuel electrode side through the electrolyte membrane.

  By the way, the single cell used in SOFC is unable to follow the temperature change due to physical deformation if the temperature is rapidly raised or lowered so as to shorten the time from starting to reach the operating temperature because the operating temperature is high. Cracks may occur. For this reason, there is a demand to quantitatively evaluate the crack generation mechanism of a single cell in the temperature change in the temperature rising / falling operation and the temperature distribution on the cell surface.

  Patent Document 1 listed below describes detection using an acoustic emission method (AE method) as a method for detecting a damage process of a single cell during power generation. The AE method is a passive method for detecting an elastic wave (acoustic emission wave: AE wave) generated by releasing the distortion stored in the object as elastic energy when the object to be inspected is deformed or cracked. Yes, it is possible to determine the presence or absence of cracks in the single cell caused by deformation factors such as temperature changes.

“Visualization of Damage Process in Solid Oxide Fuel Cell” Proceedings of the Japan Society of Mechanical Engineers (Part A) Vol. 76, No. 762 (2010-2) 97-106

  In Non-Patent Document 1, a broadband piezoelectric transducer (AE sensor) is attached to the outer surface of the ceramic tube in order to measure AE waves generated by cracks generated in the single cell. Since the optimal installation position of the AE sensor differs depending on the size relationship and the inspection environment, a certain degree of skill is required to determine the appropriate installation position of the AE sensor.

  Further, the AE sensor has an effective sensitivity for acquiring signals in the ultrasonic band (several tens of kHz to several MHz) in order to detect acoustic emission generated in the object to be inspected. Therefore, it is easily affected by surrounding background noise (noise component), and a signal (AE wave) caused by a crack generated in the cell and other signals (for example, AE caused by damage due to thermal expansion of the seal member). Wave) is difficult to classify. In particular, when a crack generated in a single cell is a micro size, the AE wave when the crack is generated is very weak, so that it is very difficult to accurately detect the crack.

  Another approach for crack detection is to observe the cell voltage. Normally, when a crack occurs in a single cell, the cell voltage decreases due to the effect of the crack. However, even if a micro-order micro crack occurs, the cell voltage does not change significantly, so observe the cell voltage. However, it was impossible to accurately detect minute cracks.

  Therefore, the present invention has been made in view of the above-mentioned problems, and it is highly accurate even if cracks generated in a single cell in a power generation state are micro ones regardless of the skill level of the operator. And it aims at providing the cell evaluation system and method which can detect the presence or absence of a crack simply and can evaluate the relationship between temperature and a crack quantitatively.

In order to achieve the above object, a first aspect according to the present invention is a cell evaluation system for evaluating a single cell for a solid oxide fuel cell configured by sandwiching an electrolyte between a fuel electrode and an air electrode. There,
An air gas introduction space for introducing air gas to the air electrode side of the single cell and a fuel gas introduction space for introducing fuel gas to the fuel electrode side of the single cell are formed with the single cell as a boundary. As described above, a holding unit that holds and holds the single cell between the air electrode side holder and the fuel electrode side holder via the seal member,
A heating section for heating the single cell to an operating temperature necessary for power generation;
An air gas supply / exhaust unit that introduces the air gas into the air gas introduction space and exhausts the air gas in the air gas introduction space;
The fuel gas is introduced into the fuel gas introduction space so that the back pressure of the fuel gas introduction space is higher than the back pressure of the air gas introduction space, and the fuel gas in the fuel gas introduction space is exhausted. A fuel gas supply / exhaust section,
A gas detection unit that detects the fuel gas contained in the air gas exhausted from the air gas supply / exhaust unit and outputs a detection signal based on the detection result;
A control unit that determines the presence or absence of a crack generated in the single cell based on the detection signal output from the gas detection unit;
A cell evaluation system comprising:

According to a second aspect of the present invention, in the cell evaluation system according to the first aspect, comprising a temperature detection means for detecting a surface temperature of the single cell,
The gas detection unit is configured to output a detection signal indicating a gas concentration of the fuel gas,
The control unit plots the detection signal output from the gas detection unit and the temperature information detected by the temperature detection unit to correlate the temperature and gas concentration before and after the occurrence of a crack in the single cell. A cell evaluation system is characterized in that cell evaluation data is generated.

  According to a third aspect of the present invention, in the cell evaluation system according to the first aspect or the second aspect, the heating unit includes a plurality of insertion holes formed on side surfaces of the air electrode side holder and the fuel electrode side holder. A cell evaluation system, characterized in that it is a cartridge-type heater inserted into the battery.

A fourth aspect of the present invention is a cell evaluation method for evaluating a single cell for a solid oxide fuel cell configured by sandwiching an electrolyte between a fuel electrode and an air electrode,
An air gas introduction space for introducing air gas to the air electrode side of the single cell and a fuel gas introduction space for introducing fuel gas to the fuel electrode side of the single cell are formed with the single cell as a boundary. And sandwiching and holding the single cell between the air electrode side holder and the fuel electrode side holder via the seal member,
Heating the single cell to an operating temperature required for power generation;
Introducing the air gas into the air gas introduction space and exhausting the air gas in the air gas introduction space;
The fuel gas is introduced into the fuel gas introduction space so that the back pressure of the fuel gas introduction space is higher than the back pressure of the air gas introduction space, and the fuel gas in the fuel gas introduction space is exhausted. And steps to
Detecting the fuel gas contained in the air gas exhausted from the air gas introduction space, and outputting a detection signal based on the detection result;
Determining the presence or absence of cracks occurring in the single cell based on the detection signal;
It is a cell evaluation method characterized by including.

  According to the present invention, air gas and fuel gas are respectively introduced into an air gas introduction space and a fuel gas introduction space formed with a single cell as a boundary, and the fuel gas is detected from the gas components exhausted from the air gas introduction space. It is determined that a crack has occurred. This makes it possible to determine whether or not a crack has occurred in a single cell based on whether or not the fuel gas is contained in the air gas. Micro cracks in the micro-order generated in the single cell inside can be detected with high accuracy.

  In addition, cell evaluation data plotting the correlation between the temperature of the single cell surface measured by the temperature detection means and the gas concentration of the fuel gas contained in the air gas introduction space can be created. It is possible to quantitatively evaluate the growth process of the crack of the single cell generated along with this.

  Furthermore, since the heating part is composed of a plurality of cartridge type heaters and inserted into the insertion holes formed in the air electrode side holder and the fuel electrode side holder, respectively, the cell part can be heated from the vertical direction. Thus, the temperature can be raised to the operating temperature more efficiently than heating the entire space, and the heating time can be greatly shortened. In addition, since the heater is composed of multiple heaters, the temperature of the cell surface in the single cell can be partially controlled, and the mechanism of cracking of the single cell due to temperature changes and the cracking caused by temperature rise / fall It is possible to evaluate the performance of a single cell while observing the growth process.

It is a schematic block diagram which shows the structure of the cell evaluation system which concerns on this invention. It is a schematic block diagram which shows the state which accommodated the holding | maintenance part in the system in the storage container. It is a graph which shows an example of the cell evaluation data which showed the correlation with the temperature of the single cell surface where the crack generate | occur | produced in the electric power generation state, and the hydrogen concentration which is fuel gas. It is a graph which shows the other example of the cell evaluation data which showed the correlation with the temperature of the single cell surface where the crack generate | occur | produced in the electric power generation state, and the hydrogen concentration which is fuel gas.

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

  Note that the drawings attached to the present specification may be schematically expressed by appropriately changing the scale, vertical / horizontal dimension ratio, shape, etc. from the actual one for convenience of illustration and easy understanding. However, the interpretation of the present invention is not limited. Therefore, the present invention is not limited by the embodiment described with reference to the accompanying drawings, and all other forms, examples, operation techniques, and the like that can be considered by those skilled in the art based on this embodiment are included in the present invention. It shall be included in the category.

  In this specification, in the following description with reference to the accompanying drawings, when the words “up”, “down”, “left”, and “right” are used to indicate directions and positions, this is indicated by the user as shown in the drawings. Matches top, bottom, left, and right.

[System configuration]
First, the configuration of the cell evaluation system according to the present invention will be described.
In the cell evaluation system 1 of the present embodiment, the single cell S1 that constitutes the SOFC cell part S is an object to be inspected, and two types of gas (fuel gas and air gas) used during power generation leak from the crack. Based on the detection result of whether or not the other gas (fuel gas) is contained in the other gas (air gas), the crack growth process caused by the judgment of the presence of cracks and temperature change is quantitatively evaluated System.

  Therefore, the crack generated in the single cell S1 in the system of the present invention is formed continuously from the front surface (air electrode) side to the back surface (fuel electrode) side of the single cell S1, and the degree of damage is such that gas can leak. Damage that is formed only on the surface of the single cell S1 or damage that remains inside the single cell S1 without reaching the back surface from the front surface is excluded from detection. In the present embodiment, as shown in FIGS. 1 and 2, the cracks formed in the single cell S <b> 1 are schematically shown by thick broken lines.

  As shown in FIG. 1, the cell evaluation system 1 according to the present embodiment includes a holding unit 10 that holds and holds each component constituting the cell unit S including the single cell S1, and a holding unit that holds air gas that is the first gas. An air gas supply / exhaust unit 20 for supplying / exhausting to the fuel gas, a fuel gas supply / exhaust unit 30 for supplying / exhausting the fuel gas as the second gas to the holding unit 10, and a fuel gas on the air gas supply / exhaust unit 20 side A gas detection unit 40 to detect, a heating unit 50 that heats the cell unit S to a predetermined operating temperature during power generation, and a control unit 60 that determines whether or not a crack has occurred in the single cell S1 and controls the driving of each unit. It consists of and.

<Cell part>
The cell portion S is a member that is configured by a single cell S1, a pair of sealing members S2, an air electrode current collector S3, and a fuel electrode current collector S4, and is sandwiched and held by the holding portion 10.

The single cell S1 includes, for example, YSZ (yttria stabilized zirconia) or ScSZ (cathode) between a fuel electrode (anode) such as YSZ / Ni cermet and an air electrode (cathode) such as (La, Sr) MnO _3. Scandia stabilized zirconia) and other electrolytes are integrated. The configuration of the single cell S1 is not limited to the above materials as long as it is a conventionally known form.

  The pair of seal members S2 are arranged to face each other with the outer peripheral edge of the single cell S1 interposed therebetween for preventing gas leakage, and are made of elastic ceramics (for example, vermiculite, mica, alumina fiber, etc.) or a glass O-ring.

  The air electrode current collector S3 is made of, for example, a net made of gold (Au) or platinum (Pt), which is a noble metal that hardly oxidizes at high temperatures. Further, the fuel electrode current collector S4 is formed of a Ni net or the like that is stable in a reducing atmosphere. The opening shapes formed in the air electrode current collector S3 and the fuel electrode current collector S4 are designed so that the gas flow is optimized in consideration of power generation efficiency. Therefore, when performing the performance evaluation of the single cell S1, it is preferable to prepare a plurality of types of collectors S3 and S4 having different opening shapes.

<Holding part>
The holding portion 10 is configured to be assembled by being fastened and fixed by the fixing member 13 in a state where the cell portion S is held between the air electrode side holder 11 and the fuel electrode side holder 12 which function as a pair of holding members. In FIG. 1, the cell part S is laminated | stacked in order of the sealing member S2, the collector S3 for air electrodes, the single cell S1, the seal member S2, and the collector S4 for fuel electrodes from the upper direction.

  The air electrode side holder 11 is disposed on the air gas supply / exhaust unit 20 side, and the fuel electrode side holder 12 is disposed on the fuel gas supply / exhaust unit 30 side. In FIG. 1, the air electrode side holder 11 is disposed above the cell portion S, the fuel electrode side holder 12 is disposed below, and the single cell S1 is placed between the air electrode side holder 11 and the fuel electrode side with the seal member S2 interposed. It is sandwiched and held with the holder 12.

  As a result, as shown in FIG. 1, an air gas introduction space E1 is formed on the air electrode side of the single cell S1, with the single cell S1 held by the holding unit 10 as a boundary, and on the fuel electrode side of the single cell S1. A fuel gas introduction space E2 is formed. The air electrode current collector S3 is accommodated in the air gas introduction space E1, and the fuel electrode current collector S4 is accommodated in the fuel gas introduction space E2.

  In the air gas introduction space E1 and the fuel gas introduction space E2, since the airtightness of each space is secured by the sealing member S2 with the single cell S1 as a partition wall, there is no gas leakage to the outside and no entry of outside air. No gas leaks from one space (for example, air gas introduction space E1) side to the other space (for example, fuel gas introduction space E2) side in a state where no crack is generated in the cell S1.

  The air electrode side holder 11 has an air gas introduction port 11a for introducing air gas into the air gas introduction space E1 and an air gas exhaust port 11b for exhausting the air gas introduced into the air gas introduction space E1 to the outside. It is formed and functions as a clamping member for clamping the cell part S, and also has a function of a manifold for supplying / exhausting air gas.

  Air gas introduced from the air gas inlet 11a is introduced from a gas inlet (not shown) formed to communicate with the air gas inlet 11a on the surface of the air electrode side holder 11 on the unit cell S1 side. It is introduced into the space E1. Further, a gas outlet (not shown) is formed in the vicinity of the gas inlet in the air electrode side holder 11 so as to communicate with the air gas outlet 11b, and the air gas in the air gas introduction space E1 is exhausted from this gas outlet. Is done.

  The fuel electrode side holder 12 has a fuel gas introduction port 12a for introducing fuel gas into the fuel gas introduction space E2 and a fuel gas exhaust port 12b for exhausting the fuel gas introduced into the fuel gas introduction space E2 to the outside. It is formed and functions as a clamping member for clamping the cell part S, and also has a function of a manifold for supplying / exhausting fuel gas.

  The fuel gas introduced from the fuel gas inlet 12a is introduced from a gas inlet (not shown) formed to communicate with the fuel gas inlet 12a on the surface of the fuel electrode side holder 12 on the single cell S1 side. It is introduced into the space E2. Further, a gas outlet (not shown) is formed in the vicinity of the gas inlet in the fuel electrode side holder 12 so as to communicate with the fuel gas outlet 12b, and the fuel gas in the fuel gas introduction space E2 flows from this gas outlet. Exhausted.

  The fixing member 13 includes an alumina bolt having heat resistance, an alumina nut screwed to the bolt, and a ceramic spring for absorbing the influence of thermal expansion due to the ambient temperature. The holding unit 10 is assembled by tightening and fixing with a nut with a ceramic spring interposed between bolts in a state where the air electrode side holder 11 and the fuel electrode side holder 12 are brought into contact with each other and the cell part S is sandwiched therebetween.

<Air gas supply / exhaust section>
The air gas supply / exhaust unit 20 is supplied from an air gas supply source G1 to an air gas introduction space E1 formed with the single cell S1 held by the holding unit 10 as a boundary, such as oxygen (O ₂ ) or air. An air gas introduction means 21 for introducing an oxygen-containing gas) and an air gas exhaust means 22 for exhausting the air gas filled in the air gas introduction space E1 to the outside. The air gas introduction means 21 is connected to the air gas introduction port 11a, and the air gas exhaust means 22 is connected to the air gas exhaust port 11b.

  The air gas supply / exhaust unit 20 controls the flow rate of air gas (control of supply amount and exhaust amount per unit time) while controlling an unillustrated supply / exhaust pump, on-off valve, and the like under the control of the control unit 60.

<Fuel gas supply / exhaust section>
The fuel gas supply / exhaust unit 30 is supplied from a fuel gas supply source G2 to a fuel gas introduction space E2 formed with the single cell S1 held by the holding unit 10 as a boundary, for example, hydrogen (H ₂ ), carbon monoxide ( CO), hydrocarbon)) and a fuel gas exhaust means 32 for exhausting the fuel gas filling the fuel gas introduction space E2 to the outside. The fuel gas introduction means 31 is connected to the fuel gas introduction port 12a, and the fuel gas exhaust means 32 is connected to the fuel gas exhaust port 12b. In addition, the fuel gas supply / exhaust unit 30 includes humidifying means 33 that humidifies the fuel gas supplied to the holding unit 10 so as to have a predetermined dew point temperature.

  The fuel gas supply / exhaust unit 30 controls the flow rate of fuel gas (control of supply amount and exhaust amount per unit time) and humidification means 33 while controlling an unillustrated supply / exhaust pump, on-off valve, and the like under the control of the control unit 60. Dew point control is performed.

  The fuel gas supply / exhaust section 30 is set so that the back pressure of the fuel gas exhaust means 32 is higher than the back pressure of the air gas exhaust means 22 by a predetermined pressure (for example, 1 to 2 kPa). That is, the pressure in the fuel gas introduction space E2 is made higher than the pressure in the air gas introduction space E1 so that a differential pressure is generated between the pressure in the air gas introduction space E1 and the pressure in the fuel gas introduction space E2. .

  Thereby, when the crack has arisen in the single cell S1, the fuel gas with which the fuel gas introduction space E2 is filled can be leaked to the air gas introduction space E1. Also, when hydrogen is used as the fuel gas and oxygen is used as the air gas, hydrogen has a lower molecular weight than oxygen, so it is easier to leak from cracks, and it is possible to detect minute cracks with higher accuracy. It becomes.

<Gas detector>
The gas detection unit 40 includes a gas detection device for detecting fuel gas leaked from the crack generated in the single cell S1 into the air gas introduction space E1, and is disposed on the flow path of the air gas exhaust unit 22. The gas detection unit 40 detects the fuel gas to be detected from the gas exhausted by the air gas exhaust means 22, and indicates whether or not it exists in the atmosphere in the air gas introduction space E1, or the gas of the fuel gas A signal indicating the density is output to the control unit 60 as a detection signal. Although the detection timing of the fuel gas and the output timing of the detection signal by the gas detection unit 40 can be arbitrarily set, it is preferable to set the fuel detection unit 40 so that it can always be detected and output during cell evaluation.

As a configuration of the gas detection unit 40, for example, a known gas sensor can be used, and can be appropriately selected according to the component of the fuel gas to be detected.
For example, when hydrogen is used as the fuel gas, a hydrogen sensor can be used. As a detection principle of the hydrogen sensor, a constant potential electric field type or a heat conduction method is known. Since the constant potential electric field type can detect fuel gas with very high sensitivity, the fuel gas is contained in the air gas introduction space E1. It is suitable for simple crack detection to determine whether or not it is present, and the heat conduction method can detect the fuel gas contained in the air gas introduction space E1 to a gas concentration of 100 vol%, so that the crack growth process, etc. It is suitable for creating detailed cell evaluation data.

  Further, the gas detection unit 40 may use a gas chromatography that analyzes a gas collected from the air gas exhaust unit 22 and identifies a component of the fuel gas to be detected in addition to a known gas sensor.

<Heating section>
The heating unit 50 is configured by a heating device such as a cartridge type heater inserted in the holding unit 10 or an electric furnace that heats the holding unit 10 in a state in which it is accommodated.

  As shown in FIG. 2, the heating unit 50 of the present embodiment is provided with a plurality of insertion holes 11 c and 12 c on the side surfaces of the air electrode side holder 11 and the fuel electrode side holder 12, and the insertion holes 11 c and 12 c have a cylindrical shape. A plurality of cartridge type heaters are inserted.

  Advantages of adopting the cartridge type heater are that the temperature of the cell surface in the single cell S1 can be partially controlled, so that the generation mechanism of cracks in the single cell S1 due to temperature change and the cracks caused by temperature rise / fall It is possible to evaluate the performance of the single cell S1 while observing the growth process. Moreover, since the upper and lower sides of the cell part S are surrounded by the heater, it is possible to significantly shorten the time until the operating temperature is reached as compared with the electric furnace.

  When heating the holding unit 10 with the heating unit 50 during power generation, it is preferable to heat the entire housing in a state in which the holding unit 10 is housed in a housing container 100 formed of a heat insulating material from the viewpoint of increasing heating efficiency. As shown in FIG. 2, openings 101 are formed on both side surfaces of the storage container 100, and one or both of the openings 101 are appropriately opened / closed using a partition member 102, so that the temperature condition inside the container can be changed. It can be varied appropriately. Further, a blower 103 such as a blower can be used from the opening 101 in order to promote heat circulation in the container. The control unit 60 performs the air volume / wind direction control of the air blowing means 103.

<Control unit>
The control unit 60 is configured by various hardware such as a CPU, a ROM, and a RAM, for example, and performs drive control and arithmetic processing of each unit constituting the cell evaluation system 1.

  Further, the control unit 60 performs temperature control of the heating unit 50. As the temperature control of the heating unit 50 by the control unit 60, for example, when the heating unit 50 is composed of a plurality of cartridge-type heaters, a plurality of heaters are used so that the cell surface temperature of the single cell S1 has a desired temperature distribution. What is necessary is just to perform drive control suitably.

Furthermore, the control unit 60 determines whether or not a crack has occurred in the single cell S1 based on the detection signal output from the gas detection unit 40. That is, in the crack presence / absence determination process, it is determined that there is a crack when the gas detection unit 40 outputs a detection signal indicating that the fuel gas is detected regardless of the concentration. And, to the external terminal device (PC, smartphone, tablet terminal, etc.) operated by the worker on the result of determining the presence or absence of cracks, a well-known communication network (local communication network such as LAN, mobile communication network of mobile carrier, Via the Internet).
The determination result determined by the control unit 60 is stored in an external storage device (HDD, SD card, flash USB memory, etc.) (not shown) so that an operator can retrieve the recorded data from the external storage device. Good.

  Further, the control unit 60 plots the gas concentration detected by the gas detection unit 40 and the temperature information of the heating unit 50 to quantitatively evaluate the growth process of the crack from the correlation between the gas concentration and the temperature. Create cell evaluation data for. The created cell evaluation data is transmitted to an external terminal device via a known communication network. The cell evaluation data can be stored in an external storage device (not shown). In addition, the temperature data at the time of producing cell evaluation data measures the surface temperature of the single cell S1 by the temperature detection means 70 comprised with temperature sensors, such as a thermocouple.

  FIG. 3 shows an example of cell evaluation data showing the correlation between the gas concentration and the temperature difference, where the vertical axis is the gas concentration of hydrogen as the fuel gas, and the horizontal axis is the temperature difference in the cell plane by the heating unit 50. It is a graph. As shown in FIG. 3, when the temperature difference between the single cell S1 and the cartridge heater is increased from 20 ° C. and the temperature difference is increased, the hydrogen concentration rapidly increases around 150 ° C. It was confirmed that This indicates that hydrogen leaking from a crack generated in the single cell S1 due to a temperature difference is detected. That is, when this system is adopted, it can be confirmed that hydrogen that has passed through the crack generated due to the temperature difference leaks into the air gas introduction space E1, and therefore the presence or absence of the crack can be easily determined.

  FIG. 4 is a graph showing an example of cell evaluation data in which the vertical axis represents the gas concentration of hydrogen as the fuel gas and the horizontal axis represents the temperature difference in the cell plane by the heating unit 50, showing the crack growth process. As shown in FIG. 4, it was detected that a crack occurred when the temperature difference of the single cell S1 was around 100 ° C., and hydrogen leaked from this crack. Further, when hydrogen was switched to nitrogen once and then switched again to hydrogen at around 150 ° C., more hydrogen was detected. This indicates that as the temperature difference is increased, cracks grow and expand, the amount of hydrogen leakage increases, and the gas concentration increases. Therefore, when this system is adopted, it is possible to quantitatively evaluate the crack growth process caused by the temperature difference in the cell plane.

[Processing operation]
Next, the processing operation of the cell evaluation system 1 described above will be described.
Here, the gas detection unit 40 determines whether or not there is a crack in the single cell S1 depending on whether or not the fuel gas is contained in the air gas introduction space E1, and the correlation between the temperature and the gas concentration when the crack is detected. This is processing until cell evaluation data indicating the relationship is created.

  First, a pair of seal members S2 are interposed between the air electrode side holder 11 and the fuel electrode side holder 12 so that the cell portion S including the single cell S1 is sandwiched and fastened by the fixing member 13 Fix it. The air electrode current collector S3 is accommodated in the air gas introduction space E1 formed with the single cell S1 as a boundary, and the fuel electrode current collector S4 is accommodated in the fuel gas introduction space E2.

  Next, a power generation operation is performed. In the power generation operation, heating is started by controlling the heating unit 50, air gas is introduced from the air gas supply / exhaust unit 20, and fuel gas is introduced from the fuel gas supply / exhaust unit 30. As a result, air gas is introduced into the air gas introduction space E1, and fuel gas is introduced into the fuel gas introduction space E2.

Next, the fuel gas is detected by the gas detection unit 40 in the power generation state.
At this time, if no crack is generated in the single cell S1, the fuel gas is not leaked from the crack, so that the fuel gas is not detected by the gas detection unit 40. Therefore, the gas detection unit 40 outputs a detection signal indicating non-detection of the fuel gas to the control unit 60.
On the other hand, when a crack is generated in the single cell S1, the fuel gas leaks from the crack to the air gas introduction space E1, and the gas detection unit 40 detects the fuel gas. Therefore, the gas detection unit 40 outputs a detection signal indicating the gas concentration of the detected fuel gas to the control unit 60.

The control unit 60 determines whether or not a crack has occurred in the single cell S <b> 1 based on the detection signal output from the gas detection unit 40. When the input detection signal is a signal indicating no gas detection, it is determined that no crack has occurred in the single cell S1.
On the other hand, if the input detection signal is a signal indicating the gas concentration, it is determined that a crack has occurred in the single cell S1, and the current surface temperature of the single cell S1 measured by the temperature detection means 70 and the detected fuel. Cell evaluation data is created by plotting the gas concentration of the gas.

[Action / Effect]
As described above, the cell evaluation system 1 described above has the air electrode side holder 11 and the fuel electrode side holder so that the air gas introduction space E1 and the fuel gas introduction space E2 are formed with the single cell S1 as a boundary. 12 is sandwiched and held via a pair of seal members S2. Further, air gas is introduced from the air gas supply / exhaust unit 20 into the air gas introduction space E1 by providing a differential pressure so that the back pressure of the fuel gas introduction space E2 is higher than the back pressure of the air gas introduction space E1. At the same time, the fuel gas is introduced from the fuel gas supply / exhaust section 30 into the fuel gas introduction space E2. When the fuel gas is detected by the gas detector 40, it is determined that a crack has occurred in the single cell S1.

  Thereby, when a crack occurs in the single cell S1, it is possible to detect a micro-order crack with high accuracy only by detecting the fuel gas contained in the air gas. In addition, since the presence or absence of a crack can be determined by simply detecting the leakage of the fuel gas from the crack generated in the single cell S1, even an inexperienced worker can easily perform an inspection without requiring a special technique.

  Furthermore, since cell evaluation data plotting the correlation between the surface temperature of the single cell S1 measured by the temperature detecting means 70 and the gas concentration of the fuel gas contained in the air gas introduction space E1 can be created, It is possible to quantitatively evaluate the growth process of the cracks of the single cell S1 generated with the temperature rise. That is, it becomes possible to grasp how much temperature change occurs in the single cell S1 to be inspected and how the temperature increase / decrease operation is performed to expand the crack.

  Further, the heating unit 50 is composed of a plurality of cartridge-type heaters and is inserted into the insertion holes 11c and 12c formed in the air electrode side holder 11 and the fuel electrode side holder 12, respectively, and the cell unit S is heated from above and below. Therefore, it is possible to raise the temperature to the operating temperature more efficiently than to heat the entire space like an electric furnace, and the heating time can be greatly shortened. Further, since a plurality of heaters are used, the temperature of the cell surface in the single cell S1 can be partially controlled, and the generation mechanism of cracks in the single cell S1 due to a temperature change and accompanying temperature increase / decrease It is possible to evaluate the performance of the single cell S1 while observing the growth process of cracks.

  In addition, when the detected fuel gas is determined from the gas concentration per unit time, it can be detected if the correlation between the crack size and the gas concentration per unit time is quantitatively known. It is also possible to estimate the approximate size of the crack (that is, the degree of damage to the single cell S1) from the gas concentration of the fuel gas.

DESCRIPTION OF SYMBOLS 1 ... Cell evaluation system 10 ... Holding part 11 ... Air electrode side holder (11a ... Air gas introduction port, 11b ... Air gas exhaust port, 11c ... Insertion hole)
12 ... Fuel electrode side holder (12a ... Fuel gas introduction port, 12b ... Fuel gas exhaust port, 12c ... Insertion hole)
DESCRIPTION OF SYMBOLS 13 ... Fixed member 20 ... Air gas supply / exhaust part 21 ... Air gas introduction means 22 ... Air gas exhaust means 30 ... Fuel gas supply / exhaust part 31 ... Fuel gas introduction means 32 ... Fuel gas exhaust means 40 ... Gas detection part 50 ... Heating Reference numeral 60: Control unit 70: Temperature detection means E1: Air gas introduction space E2: Fuel gas introduction space G1: Air gas supply source G2: Fuel gas supply source S: Cell part (S1: Single cell, S2: A pair of seal members , S3 ... current collector for air electrode, S4 ... current collector for fuel electrode)

Claims (4)

A cell evaluation system for evaluating a single cell for a solid oxide fuel cell configured by sandwiching an electrolyte between a fuel electrode and an air electrode,
An air gas introduction space for introducing air gas to the air electrode side of the single cell and a fuel gas introduction space for introducing fuel gas to the fuel electrode side of the single cell are formed with the single cell as a boundary. As described above, a holding unit that holds and holds the single cell between the air electrode side holder and the fuel electrode side holder via the seal member,
A heating section for heating the single cell to an operating temperature necessary for power generation;
An air gas supply / exhaust unit that introduces the air gas into the air gas introduction space and exhausts the air gas in the air gas introduction space;
The fuel gas is introduced into the fuel gas introduction space so that the back pressure of the fuel gas introduction space is higher than the back pressure of the air gas introduction space, and the fuel gas in the fuel gas introduction space is exhausted. A fuel gas supply / exhaust section,
A gas detection unit that detects the fuel gas contained in the air gas exhausted from the air gas supply / exhaust unit and outputs a detection signal based on the detection result;
A control unit that determines the presence or absence of a crack generated in the single cell based on the detection signal output from the gas detection unit;
A cell evaluation system comprising: Temperature detecting means for detecting the surface temperature of the single cell;
The gas detection unit is configured to output a detection signal indicating a gas concentration of the fuel gas,
The control unit plots the detection signal output from the gas detection unit and the temperature information detected by the temperature detection unit to correlate the temperature and gas concentration before and after the occurrence of a crack in the single cell. The cell evaluation system according to claim 1, wherein cell evaluation data to be shown is created.   3. The cell evaluation system according to claim 1, wherein the heating unit is a cartridge-type heater that is inserted into a plurality of insertion holes formed in side surfaces of the air electrode side holder and the fuel electrode side holder. A cell evaluation method for evaluating a single cell for a solid oxide fuel cell configured by sandwiching an electrolyte between a fuel electrode and an air electrode,
An air gas introduction space for introducing air gas to the air electrode side of the single cell and a fuel gas introduction space for introducing fuel gas to the fuel electrode side of the single cell are formed with the single cell as a boundary. And sandwiching and holding the single cell between the air electrode side holder and the fuel electrode side holder via the seal member,
Heating the single cell to an operating temperature required for power generation;
Introducing the air gas into the air gas introduction space and exhausting the air gas in the air gas introduction space;
The fuel gas is introduced into the fuel gas introduction space so that the back pressure of the fuel gas introduction space is higher than the back pressure of the air gas introduction space, and the fuel gas in the fuel gas introduction space is exhausted. And steps to
Detecting the fuel gas contained in the air gas exhausted from the air gas introduction space, and outputting a detection signal based on the detection result;
Determining the presence or absence of cracks occurring in the single cell based on the detection signal;
A cell evaluation method comprising:

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