JP4924910B2 - Fuel cell device - Google Patents

Description

  The present invention relates to a fuel cell device, and more particularly to a fuel cell device capable of changing a power generation amount by following a load.

  A solid oxide fuel cell (hereinafter also referred to as “SOFC”) uses an oxide ion conductive solid electrolyte as an electrolyte, has electrodes attached to both sides thereof, and supplies fuel gas to one side. In this fuel cell device, an oxidant (air, oxygen, etc.) is supplied to the other side to generate a power generation reaction at a relatively high temperature.

  More specifically, this fuel cell apparatus (SOFC) includes a plurality of fuel cell cells that operate when fuel gas and oxidant (air, oxygen, etc.) flow from one end side to the other end side. After being supplied with reformed gas (city gas, etc.) as fuel from outside, the city gas is introduced into a reformer containing a reforming catalyst, and reformed into hydrogen-rich fuel gas Supplying to a plurality of fuel cells.

On the other hand, in the fuel cell device, it is known that when the fuel cell is damaged, the power generation performance is lowered and the module voltage of the fuel cell module is lowered.
In Patent Document 1, three power generation operation modes of High mode, Mid mode, and Low mode are set corresponding to the load power, and when the output voltage of the fuel cell drops in each mode, the output power is set from the target power value. In addition, there is described a fuel cell power generation system that can cope with a low provisional power value without greatly affecting the operating state.

Japanese Patent No. 3939978

  However, in a fuel cell device that can greatly change the amount of power generation by following the load, the voltage change of the fuel cell module also increases with the load following. For this reason, in a fuel cell device that follows a load, even if a voltage drop occurs in the fuel cell module, it cannot be distinguished whether this voltage drop is caused by load following or due to damage of the fuel cell. Therefore, even if the technique of Patent Document 1 or the like is used, it is impossible to detect the breakage of the fuel cell.

  For example, it is conceivable that the voltage drop of the fuel cell module is caused by the electrode of the fuel cell being peeled off and the peeled piece coming into contact with the adjacent fuel cell and causing a short circuit. It has been difficult to detect such breakage of the fuel cell.

  Therefore, the present invention has been made to solve the problems of the prior art, and even in a fuel cell device that can change the amount of power generation by following the load, it detects damage of the fuel cell. An object of the present invention is to provide a fuel cell device that can be used.

In order to achieve the above object, the present invention provides a fuel cell device capable of changing a power generation amount by following a load, and includes an inner electrode layer, an outer electrode layer, an inner electrode layer, and an outer electrode. A fuel cell module in which a plurality of solid oxide fuel cells each having an electrolyte layer disposed between the layers are disposed adjacent to each other, and a reaction gas used for a power generation reaction is supplied to the fuel cells Reactive gas supply means, voltage detection means for detecting a module voltage generated in the fuel cell module, and generation of predetermined power while controlling the supply amount of the reaction gas supplied to the fuel cell by the reaction gas supply means A control mode for executing a start-up mode in which the temperature of the fuel cell is raised to a power generation start temperature, and a power generation mode in which power is output from the fuel cell module while following the load after the start-up mode is executed. When the module voltage drop occurs in the start-up mode in a state where the module voltage value is rising without load, the control means has a voltage drop amount of the module voltage. If the value is larger than the value calculated from the module voltage immediately before it occurs, it is determined that the fuel cell is abnormal, and abnormality response control is executed.
In the case of a normal solid oxide fuel cell that is not damaged, the module voltage of the fuel cell module rises (starts up) depending on the temperature of the fuel cell. In addition, the solid oxide fuel cell has a high temperature of about 600 to 700 ° C. during power generation. Therefore, in the start-up mode in which the temperature is raised from room temperature to the high temperature, the heat flux entering and exiting the fuel cell module becomes large. It rises stably without receiving. Therefore, when the abnormality of the fuel cell is determined based on the voltage drop amount of the fuel cell module, it can be accurately performed if the start mode is being executed. As a result, according to the present invention, it is possible to detect abnormalities such as peeling / short-circuiting of the outer surface of the fuel cell, which is difficult to detect during load following in the power generation mode (knowledge discovered by the present inventors).
For this reason, according to the present invention configured as described above, when the voltage drop of the module voltage occurs in the startup mode in a state where the value of the module voltage is increased without load, If the voltage drop amount of the module voltage is larger than the value calculated from the module voltage immediately before the voltage drop occurs, it is determined that the fuel cell is abnormal. However, since the abnormality of the fuel cell is accurately determined and the abnormality control is executed, it is possible to execute the operation corresponding to the fuel cell module whose power generation performance is reduced.

In the present invention, preferably, the control means executes different abnormality response control according to the voltage drop amount of the fuel cell module.
In the present invention configured as described above, the voltage drop amount of the fuel cell module tends to increase with the degree of damage of the fuel cell, so that the fuel cell according to the degree of damage of the fuel cell. It is possible to execute abnormality response control suitable for the cell.

In the present invention, preferably, the control means continuously determines the abnormality of the fuel cell in the startup mode even after determining the abnormality of the fuel cell.
In the present invention configured as described above, since the abnormality of the fuel cell is continuously determined even after the determination of the abnormality of the fuel cell, the module voltage is once determined to be abnormal. Even when the abnormality is resolved and the abnormality is resolved, it is possible to reliably detect the damage of the fuel cell.

In the present invention, preferably, the abnormality response control by the control means is to notify the abnormality of the fuel cell and stop the operation.
In the present invention configured as described above, the abnormality of the fuel cell is notified and the operation is stopped, so that the user can be urged to repair or replace the fuel cell module or the fuel cell. .

In the present invention, preferably, the abnormality response control by the control means stops the operation when the voltage drop amount of the fuel cell module is larger than a predetermined value, and continues the operation when the voltage drop amount is smaller than the predetermined value.
In the present invention configured as described above, when the amount of voltage drop of the fuel cell module is larger than a predetermined value, that is, when the degree of damage of the fuel cell is large, the operation is stopped and the fuel cell If the amount of voltage drop of the fuel cell module is smaller than a predetermined value, that is, if the degree of damage of the fuel cell is small, the power generation performance can be restored by prompting repair or replacement. Power generation can be performed while the performance is reduced.

In the present invention, preferably, when the voltage drop amount of the fuel cell module is smaller than a predetermined value and the operation is continued, the control means sets the maximum power generation amount in the subsequent power generation mode when the fuel cell is normal. It was made to lower than the maximum power generation amount.
In the present invention configured as described above, when the voltage drop amount of the fuel cell module is smaller than the predetermined value and the operation is continued, the maximum power generation amount in the power generation mode executed thereafter is normal for the fuel cell. Therefore, further damage to the fuel cells caused by power generation can be reduced. Here, “the power generation mode executed thereafter” means “power generation mode” after the start-up mode in the next operation of the fuel cell device when it is determined that the fuel cell is abnormal in the stop mode. To do.

In the present invention, preferably, the abnormality countermeasure control of the control means is such that the supply amount of the reaction gas is increased from the supply amount when the fuel cell is normal.
In the present invention configured as described above, the supply amount (flow rate per unit time) of the reaction gas is increased from the supply amount when the fuel cell is normal. The peeling piece etc. which are short-circuiting between battery cells can be blown off, and short circuit elimination and voltage recovery can be aimed at.

  According to the fuel cell device of the present invention, even if the fuel cell device can change the amount of power generation by following the load, damage of the fuel cell can be detected.

1 is a perspective view showing a fuel cell module in a state where a cover member of a fuel cell device according to an embodiment of the present invention is removed. It is sectional drawing which looked at the fuel cell module of the fuel cell apparatus by one Embodiment of this invention from the A direction of FIG. It is sectional drawing which looked at the fuel cell module of the fuel cell apparatus by one Embodiment of this invention from the B direction of FIG. It is a front view which shows the fuel cell unit of the fuel cell apparatus by one Embodiment of this invention. It is a perspective view which shows the fuel cell stack of the fuel cell apparatus by one Embodiment of this invention. It is a perspective view of the fuel cell module which shows the state which removed the flow-path member from the fuel cell module shown in FIG. It is a perspective view of the fuel cell module which shows the state which removed the fuel cell unit, the reformer, etc. from the fuel cell module shown in FIG. It is the schematic which shows the fuel cell module of the fuel cell apparatus by 1st embodiment of this invention. 1 is a block diagram showing a fuel cell device according to an embodiment of the present invention. It is a time chart which shows the operation | movement at the time of execution of starting mode of the fuel cell apparatus by one Embodiment of this invention. It is a photograph which shows the peeling piece peeled from the electrode surface. It is a partial top view of a fuel cell stack showing a current path short-circuited by a strip. It is a time chart which shows the 1st case which the short circuit generate | occur | produced during execution of starting mode in a fuel cell apparatus, and it eliminated after that. It is a time chart which shows the 2nd case where a short circuit occurred during starting mode execution in a fuel cell device, but was not canceled after that. It is a time chart which shows the 3rd case which the short circuit generate | occur | produced during execution of the stop mode in a fuel cell apparatus, and it eliminated after that. It is a time chart which shows the 4th case which a short circuit occurred during stop mode execution in a fuel cell device, but was not canceled after that. It is a flowchart which shows the content of the abnormality determination process in the fuel cell apparatus by one Embodiment of this invention. It is a flowchart which shows the content (subroutine of S5 of FIG. 17) of the abnormality countermeasure control in the starting mode of the fuel cell apparatus by one Embodiment of this invention. It is a figure which shows the voltage at the time of starting mode completion | finish in the abnormality countermeasure control of the fuel cell apparatus by one Embodiment of this invention, the maximum generated electric current, and a fuel flow rate. It is a flowchart which shows the content (subroutine of S9 of FIG. 17) of the abnormality countermeasure control in the stop mode of the fuel cell apparatus by one Embodiment of this invention.

Hereinafter, a fuel cell device according to an embodiment of the present invention will be described with reference to the drawings.
A fuel cell device 1 according to an embodiment of the present invention is a solid oxide fuel cell (SOFC), and includes a fuel cell module 102, an auxiliary unit 104, various sensors, and the like (see FIG. 9).
First, the fuel cell module 102 of the fuel cell device 1 will be described with reference to FIGS. FIG. 1 is a perspective view showing a fuel cell module with a cover member removed from a fuel cell device according to an embodiment of the present invention, and FIG. 2 shows the fuel cell module of the fuel cell device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view seen from the direction A in FIG. 1, and FIG. 3 is a cross-sectional view seen from the direction B in FIG. 1 of the fuel cell module of the fuel cell device according to the embodiment of the present invention.

  The cover member (not explicitly shown in FIGS. 1 and 3, the outer shape of which is shown by a two-dot chain line in FIG. 2) includes a front side wall, a pair of longitudinal side walls, a back side wall, a ceiling, Is formed in a rectangular parallelepiped shape. A flange portion is formed at the lower end portion of each side wall, and a space sealed by the cover member and the base member 2 is formed by bringing the flange portion into contact with the base member 2. The cover member and the base member 2 are fixed by bolts (not shown), and the bolts pass through attachment holes provided in the cover member, and are fixed by passing through attachment holes 2a provided in the base member 2. ing.

  The internal space formed by the cover member and the base member 2 is separated into two spaces by the partition plate 15. Among the spaces separated by the partition plate 15, the space where the fuel cell stack 90 is disposed is the power generation chamber 16. Among the spaces separated by the partition plate 15, the other space is an exhaust gas chamber 17 (exhaust gas chamber). The inner wall surface of the cover member and the partition plate 15 are in close contact with each other directly or indirectly through some kind of contact member (for example, a flexible thin plate member).

  The partition plate 15 is placed on a support member 15 a provided on the base member 2 and is held at a predetermined distance from the base member 2. A pair of support members 15a are provided so as to support the partition plate 15 at both ends in the longitudinal direction. Accordingly, a gap 15b (inlet) is formed between the pair of support members 15a and 15a. Exhaust gas that has passed through an exhaust gas passage (not shown) provided on the wall surface of the cover member is introduced into the exhaust gas chamber 17 through the gap 15b. The exhaust gas introduced into the exhaust gas chamber 17 is exhausted from the exhaust port 11 (outlet) to the outside.

  The gas tank 3 is placed on the partition plate 15. Ten fuel cell stacks 90 are arranged side by side in the gas tank 3, and fuel gas is supplied from the gas tank 3 to the fuel cell 4 constituting each fuel cell stack 90.

  More specifically, an opening (not shown) having substantially the same shape as the lower support plate 90b of the fuel cell stack 90 is provided on the upper surface of the gas tank 3, and the lower support plate 90b is in close contact with the opening. Thus, the gas tank 3 and each fuel cell stack 90 are connected. Accordingly, the fuel cells 4 constituting the fuel cell stack 90 are erected on the gas tank 3 with their tip portions facing upward.

  Each fuel battery cell 4 has a tubular shape, and a gas flowing from one end of the fuel battery cell 4 to the other end inside the pipe of the fuel battery cell 4 and outside the pipe from the one end to the other end. It operates by the action of the gas flowing to the part. In the present embodiment, the gas flowing in the pipe of the fuel battery cell 4 is a fuel gas such as reformed gas obtained by reforming hydrogen or hydrocarbon fuel, and the gas flowing outside the pipe of the fuel battery cell 4 contains oxygen. An oxidant gas (air for power generation) such as air.

  Next, the fuel cell unit 30 including the fuel cells 4 will be described with reference to FIG. FIG. 4 is a front view showing a fuel cell unit of the fuel cell device according to one embodiment of the present invention. As shown in FIG. 4, the fuel cell unit 30 is a tubular structure formed by the fuel cells 4 and extending in the vertical direction, and includes a cylindrical fuel cell 4 and one end of the fuel cell 4. It has an inner electrode terminal 40 attached to 4a, and an outer electrode terminal 42 attached to the other end 4b.

  The fuel cell 4 includes a cylindrical inner electrode layer 44, a cylindrical outer electrode layer 48, a cylindrical electrolyte layer 46 disposed between the electrode layers 44, 48, and an inner electrode. And a through flow channel 50 configured inside the layer 44. Further, an inner electrode exposed peripheral surface 44a in which the inner electrode layer 44 is exposed to the electrolyte layer 46 and the outer electrode layer 48 at one end 4a of the fuel cell 4, and the electrolyte layer 46 is an outer electrode layer. An electrolyte exposed peripheral surface 46 a exposed to 48 is provided. The other end 4b of the fuel cell 4 is configured by an outer electrode exposed peripheral surface 48a from which the outer electrode layer 48 is exposed. The through channel 50 functions as a fuel gas channel. The inner electrode exposed peripheral surface 44 a is also an inner electrode outer peripheral surface that is in electrical communication with the inner electrode layer 44. The outer electrode exposed peripheral surface 48 a is also an outer electrode outer peripheral surface that is in electrical communication with the outer electrode layer 48.

  The inner electrode layer 44 includes, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, ceria doped with at least one selected from Ni and rare earth elements, And a mixture of Ni and lanthanum gallate doped with at least one selected from Sr, Mg, Co, Fe, and Cu. The electrolyte layer 46 includes, for example, zirconia doped with at least one selected from rare earth elements such as Y and Sc, ceria doped with at least one selected from rare earth elements, lanthanum gallate doped with at least one selected from Sr and Mg, Formed from at least one of the following. The outer electrode layer 48 is made of, for example, lanthanum manganite doped with at least one selected from Sr and Ca, lanthanum ferrite doped with at least one selected from Sr, Co, Ni, and Cu, Sr, Fe, Ni, and Cu. It is formed from at least one selected from lanthanum cobaltite doped with at least one selected from silver and silver. In this case, the inner electrode layer 44 becomes a fuel electrode, and the outer electrode layer 48 becomes an air electrode. The thickness of the inner electrode layer 44 is, for example, 1 mm, the thickness of the electrolyte layer 46 is, for example, 30 μm, the thickness of the outer electrode layer 48 is, for example, 30 μm, and the outer diameter is For example, it is 1-10 mm.

  The inner electrode terminal 40 is arranged so as to cover the inner electrode exposed peripheral surface 44a from the outside over the entire circumference and is electrically connected to the inner electrode terminal 40a, and a tubular shape extending from the main body portion 40a in the longitudinal direction of the fuel cell 4. Part 40b. The main body portion 40a and the tubular portion 40b are cylindrical and concentrically arranged, and the tube diameter of the tubular portion 40b is smaller than the tube diameter of the main body portion 40a. The tubular portion 40b has a connection channel 40c that communicates with the through channel 50 and communicates with the outside. A step portion 40 d between the main body portion 40 a and the tubular portion 40 b is in contact with the end surface 44 b of the inner electrode layer 44.

  The outer electrode terminal 42 is disposed so as to cover the outer electrode exposed peripheral surface 48a from the outside over the entire circumference and is electrically connected thereto, and a tubular shape extending from the main body portion 42a in the longitudinal direction of the fuel cell 4. Part 42b. The main body portion 42a and the tubular portion 42b are cylindrical and concentric, and the tube diameter of the tubular portion 42b is smaller than the tube diameter of the main body portion 42a. The tubular portion 42b has a connection channel 42c that communicates with the through channel 50 and communicates with the outside. A step portion 42 d between the main body portion 42 a and the tubular portion 42 b is in contact with the outer electrode layer 48, the electrolyte layer 46, and the end surface 44 c of the inner electrode layer 44 via the annular insulating member 52.

  The overall shape of the inner electrode terminal 40 and the overall shape of the outer electrode terminal 42 are the same. Further, the inner electrode terminal 40 and the fuel battery cell 4, and the outer electrode terminal 42 and the fuel battery cell 4 are sealed and fixed by a conductive sealing material 54 over the entire circumference. The sealing material 54 is various brazing materials including, for example, silver, a mixture of silver and glass, gold, nickel, copper, and titanium.

  The connection flow path 40 c of the inner electrode terminal 40, the through flow path 50 of the fuel cell 4, and the connection flow path 42 c of the outer electrode terminal 42 constitute an in-pipe flow path 30 c of the fuel cell unit 30.

  Next, the fuel cell stack 90 including the fuel cell unit 30 will be described with reference to FIG. FIG. 5 is a perspective view showing a fuel cell stack of a fuel cell device according to an embodiment of the present invention. The fuel cell stack 90 includes 16 fuel cell units 30, an upper support plate 90a, a lower support plate 90b, a connection member 90c, and an external terminal 90d.

  The upper support plate 90a and the lower support plate 90b are rectangular, and are through holes (fitting holes) that fit into the tubular portions 40b and 42b of the fuel cell unit 30 so as to support the fuel cell unit 30 in 2 columns × 8 rows, respectively. (Not shown in the figure). The upper support plate 90a and the lower support plate 90b are formed of an electrically insulating material, for example, formed of heat resistant ceramics. Specifically, it is preferable to use alumina, zirconia, spinel, forsterite, magnesia, titania or the like.

  The 16 fuel cell units 30 are arranged so that they are electrically connected in series. Specifically, the fuel cell units 30 are arranged so that the inner electrode terminals 40 of the adjacent fuel cell units 30 are alternately arranged on the upper side and the lower side. Further, a connection member 90c for electrically connecting the 16 fuel cell units 30 in series is provided. The connection member 90 c electrically connects one adjacent inner electrode terminal 40 and one outer electrode terminal 42. Each of the inner electrode terminal 40 and the outer electrode terminal 42 at both ends of the 16 fuel cell units 30 connected in series is provided with an external terminal 90d for electrical connection with the outside. The connection member 90c and the external terminal 90d are made of, for example, a heat resistant metal such as stainless steel, a nickel base alloy, or a chromium base alloy, or a ceramic material such as lanthanum chromite. The external terminals 90d of each fuel cell stack 90 are electrically connected in series, and are connected to the electrode rods 13 and 14 at both ends thereof.

  As described with reference to FIGS. 4 and 5, in the fuel cell stack 90, the end 4 a of the fuel cell unit 30 where the inner electrode terminal 40 is provided and the end where the outer electrode terminal 42 is provided. The parts 4b are arranged so as to alternate with each other.

  Here, returning to FIGS. 1 to 3, the description of the fuel cell module 102 will be continued. In the following description, reference is also made to FIGS. 6 is a perspective view of the fuel cell module showing a state in which the flow path member 7 is removed from the fuel cell module shown in FIG. 1, and FIG. 7 shows the fuel cell unit and the reformer 5 from the fuel cell module shown in FIG. 1 is a perspective view of a fuel cell module showing a state where a fuel cell stack 90 and a gas tank 3 are removed. In the present embodiment, the reformer 5 is disposed so as to be positioned above the fuel cell stack 90. The reformer 5 is connected to a pipe 6C (pipe) and a pipe 6D, and the pipe 6C and the pipe 6D allow the reformer 5 to move upward with a predetermined distance from the fuel cell stack 90. Is held in place. The pipe 6 </ b> C is a pipe for supplying city gas, air (reforming air) and water vapor as reformed gas to the reformer 5, and is erected with respect to the partition plate 15. The pipe 6 </ b> D is a pipe for supplying the fuel gas reformed in the reformer 5 to the gas tank 3, and is erected with respect to the gas tank 3.

The city gas and air supplied to the reformer 5 through the pipe 6C are introduced into the fuel cell module 102 through the reformed gas supply pipe 6A. Further, the steam supplied to the reformer 5 through the pipe 6C is introduced into the fuel cell module 102 through the steam supply pipe 6B (pipe).
Since the water vapor supply pipe 6B is disposed in the exhaust gas chamber 17, the water flowing in the pipe is changed into water vapor by being heated by the high temperature exhaust gas. Thus, the water vapor supply pipe 6B functions as an evaporator for generating water vapor from water.

  The to-be-reformed gas supply pipe 6A and the water vapor supply pipe 6B are connected to a mixing chamber 15c provided on the opposite side of the pipe 6C with the partition plate 15 in between. The city gas and air supplied from the reformed gas supply pipe 6A and the water vapor supplied from the steam supply pipe 6B are mixed in the mixing chamber 15c and supplied to the pipe 6C.

  Although not explicitly shown in FIGS. 1 to 3, in this embodiment, electromagnetic valves are attached to the reformed gas supply pipe 6 </ b> A and the steam supply pipe 6 </ b> B, respectively, and each electromagnetic valve is output from a CPU as a control unit. The ratio of the gas to be reformed, air, and water vapor supplied to the reformer 5 can be changed by opening and closing according to the instruction signal.

  City gas (which may be mixed with steam) and air (which may be only reformed gas) as reformed gas introduced into the reformer 5 are contained in the reformer 5. The reforming catalyst is reformed. The reformed fuel gas is supplied to the gas tank 3 through the pipe 6D. The portion where the pipe 6C is connected to the reformer 5 and the portion where the pipe 6D is connected to the reformer 5 are separated from each other in the vicinity of one end and the other end in the longitudinal direction. As a result, the fuel gas and air supplied to the reformer 5 can sufficiently touch the reforming catalyst.

  A reforming catalyst is enclosed in the reformer 5. As the reforming catalyst, a catalyst in which nickel is applied to the surface of the alumina sphere and a catalyst in which ruthenium is applied to the surface of the alumina sphere are appropriately used. These reforming catalysts are spheres.

  In the present embodiment, the flow path member 7 is provided so as to cover the reformer 5 and each fuel cell stack 90. The flow path member 7 has air flow path outer walls 71 and 72, an air distribution chamber 73, air collecting chambers 74 and 75, air flow path pipes 76a, 76b, 77a and 77b, and outer walls 78 and 79. Yes. The flow path member 7 is formed such that the air flow path outer walls 71 and 72 are arranged in the longitudinal direction and the outer walls 78 and 79 are arranged in the short direction, respectively, and are formed into a box shape by these members. The flow path member 7 is erected on the partition plate 15 so as to cover the reformer 5 and each fuel cell stack 90. In the following description, the side that contacts the partition plate 15 of the flow path member 7 is defined as the lower side, and the side opposite to the lower side is described as the upper side.

  The air distribution chamber 73 is attached to the upper outside of the outer wall 79. That is, the air distribution chamber 73 is attached to the outside of the box-shaped body formed by the air flow path outer walls 71 and 72 and the outer walls 78 and 79 and above the short side. An air supply pipe 7A is connected to the air distribution chamber 73, and air as an oxidant gas is supplied. Air flow passages 76a, 76b, 77a, 77b are also connected to the air distribution chamber 73.

  The air flow path pipes 76a and 76b are arranged along the air flow path outer wall 71 on the inner side of the box-shaped body formed by the air flow path outer walls 71 and 72 and the outer walls 78 and 79 and above the longitudinal side. Yes. The air channel tube 76a is disposed on the air channel outer wall 71 side, and the air channel tube 76b is disposed on the inner side of the air channel tube 76a. One end of each of the air flow path pipes 76 a and 76 b passes through the outer wall 79 and is connected to the air distribution chamber 73, and the other end is connected to the air collecting chamber 74. Therefore, the air that has flowed into the air distribution chamber 73 flows through the air flow path pipes 76a and 76b into the air collecting chamber 74 and rejoins.

  The air flow path pipes 77a and 77b are arranged along the air flow path outer wall 72 on the inner side and the upper side of the box-shaped body formed by the air flow path outer walls 71 and 72 and the outer walls 78 and 79. Yes. The air flow path pipe 77a is disposed on the air flow path outer wall 72 side, and the air flow path pipe 77b is disposed on the inner side of the air flow path pipe 77a. One end of each of the air passage pipes 77 a and 77 b passes through the outer wall 79 and is connected to the air distribution chamber 73, and the other end is connected to the air collecting chamber 75. Accordingly, the air flowing into the air distribution chamber 73 flows through the air flow path pipes 77a and 77b into the air collecting chamber 75 and rejoins.

  The air collecting chambers 74 and 75 are attached to the upper inside of the outer wall 78. That is, the air collecting chambers 74 and 75 are attached to the inside of the box-like body formed by the air flow path outer walls 71 and 72 and the outer walls 78 and 79 and above the short side. The air collecting chamber 74 is disposed so as to be in close contact with the air flow path outer wall 71, and the air that has flowed into the air collecting room 74 is configured to flow out to the air flow path outer wall 71. On the other hand, the air collecting chamber 75 is disposed so as to be in close contact with the air flow path outer wall 72, and the air flowing into the air collecting chamber 75 is configured to flow out to the air flow path outer wall 72.

  Each of the air flow path outer walls 71 and 72 has a double wall structure, and is configured so that air can flow through each of them. More specifically, the air flow path outer wall 71 has a structure divided into three chambers from above, and is formed as a first chamber 91, a second chamber 92, and a third chamber 93 in this order from above. The air that flows from the air collecting chamber 74 flows into the first chamber 91, then flows into the second chamber 92, and then flows into the third chamber 93. Similarly, the air flow path outer wall 72 is also divided into three chambers from above, and is formed as a first chamber 94, a second chamber 95, and a third chamber 96 in order from the top. The air flowing from the air collecting chamber 75 flows into the first chamber 94, then flows into the second chamber 95, and then flows into the third chamber 96.

  In the third chambers 93 and 96, a plurality of air inflow holes 93a and 96a are formed at predetermined intervals, respectively. The air inflow holes 93a and 96a are located in the direction in which the fuel cell stack 90 is connected to the gap between the fuel cells 4 and the vertical positions relative to the fuel cells 4 are substantially the same. A plurality of them are formed.

  The air flowing into the air flow path outer walls 71 and 72 is configured to flow into the vicinity of the fuel cell 4 in the power generation chamber 16 through the air inflow holes 93a and 96a. The air (power generation air) that flows through the air inflow holes 93 a and 96 a flows from the lower side to the upper side of each fuel cell 4 through the outside of the fuel cell 4. Air (power generation air) reaching above each fuel cell 4 is combusted together with the fuel gas that has passed through the pipe flow path of each fuel cell 4.

  Above each fuel cell stack 90 is a combustion section 18 in which air (power generation air) and fuel gas are mixed and burned. The fuel gas rises from the gas tank 3 through the in-pipe flow path 30 c of the fuel cell unit 30 toward the combustion unit 18. Further, the air flowing outside the fuel cell 4 also rises toward the combustion unit 18. An ignition device insertion hole 97 is provided in a portion of the air flow path outer wall 72 corresponding to the combustion portion 18, and an ignition device (not shown) for starting combustion of combustion gas and air burns from the ignition device insertion hole 97. Projected to the portion 18. The ignition device mixes and burns fuel gas and air. The fuel cells 4 constituting the fuel cell stack 90 are heated from above by the combustion unit 18. In addition, the air flowing through the air inflow holes 93a and 96a is also heated by the combustion in the combustion section 18 while passing through the air passage pipes 76a, 76b, 77a and 77b and the air passage outer walls 71 and 72 as described above. Is done.

  As described above, the exhaust gas generated when the fuel gas and air are mixed and burned in the combustion section 18 flows into the exhaust gas chamber 17 from the gap 15b. This inflow route will be described with reference to FIG. FIG. 8 is a schematic view showing a fuel cell module of the fuel cell device according to the first embodiment of the present invention. As shown in FIG. 8, the exhaust gas generated by mixing and burning fuel gas and air (power generation air) in the combustion unit 18 passes through the exhaust gas flow path 8 a formed in the cover 8. It faces downward and flows into the exhaust gas chamber 17 from the gap 15b. The exhaust gas flowing into the exhaust gas chamber 17 is exhausted from the exhaust port 11 to the outside.

Next, the overall configuration of the fuel cell device according to the present embodiment will be described with reference to FIG. FIG. 9 is a block diagram showing a fuel cell device according to an embodiment of the present invention.
A fuel cell device 1 that is a solid oxide fuel cell (SOFC) according to an embodiment of the present invention includes the fuel cell module 102 and the auxiliary unit 104 described above.

  The auxiliary unit 104 includes a water supply source 124 such as water supply and a water flow rate adjustment unit 128 (such as a “water pump” driven by a motor) that adjusts the flow rate of water supplied to the fuel cell module 102. .

  In addition, the auxiliary unit 104 includes a fuel supply source 130 such as city gas and a fuel flow rate adjustment unit 138 (such as a “fuel pump” driven by a motor) that adjusts the flow rate of the fuel gas. Further, the accessory unit 104 includes an air supply source 140 and an air flow rate adjustment unit 144 that adjusts the flow rate of air. The air flow rate adjustment unit 144 includes a reforming air flow rate adjustment unit and a power generation air flow rate adjustment unit.

  Next, the fuel cell module 102 includes a control unit for controlling the supply amount of fuel gas and the supply amount of water (steam) and performing control in the start mode, power generation mode, stop mode, and abnormality response control. 210 is provided. Further, the fuel cell module 102 is connected to an inverter 154 which is a power extraction unit (power conversion unit) for supplying the power generated by the fuel cell module to the outside.

Next, the sensors attached to the fuel cell device 1 according to the present embodiment will be described.
As shown in FIG. 9, the control unit 210 of the fuel cell apparatus (SOFC) 1 includes an operation device 212 having operation buttons such as “ON” and “OFF” for operation by a user, and a power generation output value ( A display device 214 for displaying various data (such as wattage) and a notification device 216 that issues an alarm (warning) in an abnormal state are connected. The notification device 216 may be connected to a remote management center and notify the management center of an abnormal state.

Next, signals from various sensors described below are input to the control unit 210.
First, the combustible gas detection sensor 220 is for detecting a gas leak, and is attached to the fuel cell module 102 and the auxiliary unit 104.
The CO detection sensor 222 detects whether or not CO in the exhaust gas that is originally discharged to the outside through the exhaust port 11 or the like has leaked to a cover member (not shown) that covers the fuel cell module 102 and the auxiliary unit 104. Is for.
The hot water storage state detection sensor 224 is for detecting the temperature and amount of hot water in a water heater (not shown).

The power state detection sensor 226 is for detecting the current, voltage, and the like of the inverter 154 and a distribution board (not shown).
The power generation air flow rate detection sensor 228 is for detecting the flow rate of power generation air supplied to the power generation chamber in which each fuel cell stack 90 is disposed.
The reforming air flow rate sensor 230 is for detecting the flow rate of the reforming air supplied to the reformer 5.
The fuel flow rate sensor 232 is for detecting the flow rate of the fuel gas supplied to the reformer 5.

The water flow rate sensor 234 is for detecting the flow rate of pure water (steam) supplied to the reformer 5.
The water level sensor 236 is for detecting the water level of a pure water tank (not shown) provided in the water supply source 124.
The pressure sensor 238 is for detecting the pressure on the upstream side outside the reformer 5.
The exhaust temperature sensor 240 is for detecting the temperature of the exhaust gas flowing into the hot water production apparatus (not shown).

The power generation chamber temperature sensor 242 is for detecting the temperature in the vicinity of the fuel cell stack 90 and estimating the temperature of the fuel cell stack 90 (that is, the fuel cell 4 itself).
The combustion chamber temperature sensor 244 is for detecting the temperature of the combustion unit 18.
The exhaust gas chamber temperature sensor 246 is for detecting the temperature of the exhaust gas in the exhaust gas chamber 17.
The reformer temperature sensor 248 is for detecting the temperature of the reformer 5 and calculates the temperature of the reformer 5 from the inlet temperature and the outlet temperature of the reformer 5.
The outside air temperature sensor 250 is for detecting the temperature of the outside air when the fuel cell device (SOFC) is disposed outdoors. Further, a sensor for measuring the humidity or the like of the outside air may be provided.

Signals from these sensors are sent to the control unit 210, which controls the water flow rate adjustment unit 128, the fuel flow rate adjustment unit 138, the reforming air flow rate adjustment unit 144, based on data from these signals. A control signal is sent to the power generation air flow rate adjustment unit 145 to control each flow rate in these units.
In addition, the control unit 210 sends a control signal to the inverter 154 to control the power supply amount and to perform abnormality response control.

  Here, the fuel cell device according to the present embodiment is a fuel cell device capable of changing the amount of power generation by following the load, and further, three modes of a start mode, a power generation mode, and a stop mode are executed. It has become.

  Next, referring to FIG. 10, the operation at the time of executing the start-up mode in the fuel cell apparatus according to the present embodiment will be described. FIG. 10 is a time chart showing the operation of the fuel cell device according to the embodiment of the present invention when the start mode is executed.

  When starting the fuel cell device, first, in order to warm up the fuel cell module 102, the fuel cell module 102 is not loaded, that is, the circuit including the fuel cell module 102 is opened. Fuel gas and air are supplied to 102. At this stage, even if fuel gas and air are present, no current flows through the circuit, so the fuel cell module 102 does not generate power.

  First, fuel gas is supplied. Specifically, the reformed gas is supplied from the fuel flow rate adjusting unit 138 to the reformed gas supply pipe 6A. At this time, the controller 210 outputs a signal to a fuel pump, an air blower (reforming air blower), and the like so as to supply a fuel gas including city gas and air (reforming air). FIG. 10 shows the fuel flow rate and the reforming air flow rate. The reformed gas supplied from the reformed gas supply pipe 6A passes through the reformer 5 and is stored in the gas tank 3 as fuel gas. Thereby, uniform and uniform supply of fuel gas to each fuel cell unit 30 is ensured. The fuel gas accumulated in the gas tank 3 flows through the in-pipe channel 30 c of the fuel cell unit 30 and acts on the inner electrode layer 44. The fuel gas that did not act reaches the upper space of each fuel cell unit 30.

  Also, air in the atmosphere (power generation air) is supplied. Specifically, the air flow rate adjusting unit 144 supplies the air to the air supply pipe 7A, and guides it from the air inflow holes 93a and 96a into the power generation chamber 16 through the path as described above. The air introduced into the power generation chamber 16 (power generation air) acts on the outer electrode layer 48. The air that did not act (power generation air) reaches above each fuel cell unit 30 (fuel cell 4).

  Next, fuel gas and air (power generation air) are combusted using an ignition device (not shown). The resulting exhaust gas becomes hot. The exhaust gas flows into the exhaust gas chamber 17 through the cover 8 (see FIG. 8). The exhaust gas that has flowed into the exhaust gas chamber 17 is discharged from the exhaust port 11.

  When the fuel gas and air (power generation air) are combusted, the temperature in the power generation chamber 16 is raised. Air (power generation air) introduced from the outside is heated by exchanging heat with the power generation chamber 16 while flowing through the above-described path. The hot exhaust gas flows into the exhaust gas chamber 17 and raises the temperature in the exhaust gas chamber 17.

  Subsequently, a gas obtained by mixing hydrocarbon-based city gas and air (reforming air) in advance is supplied to the reformer 5 (reforming step). In the reformer 5, the partial oxidation reforming reaction POX of the formula (1) proceeds. Since this partial oxidation reforming reaction is an exothermic reaction, the startability is good. Even if the partial oxidation reforming reaction POX proceeds, the combustion reaction continues in the combustion section 18.

_{C m H n + m / 2} O 2 → m CO + n / 2 H 2 (1)

  In the present embodiment, the partial oxidation reforming reaction POX according to the formula (1-1) is performed in two stages before the partial oxidation reforming reaction POX according to the formula (1). ing. When the temperature of the reformer 5 is lower than a predetermined temperature (for example, about 450 degrees), the amount of air supplied to the reformer 5 is reduced as shown in the formula (1-1), and methane is Suppresses excessive conversion to hydrogen.

C _m H _n + _{m / 8} O ₂ → _{m / 4} CO + _{n / 8} H ₂ +3 _{m / 4} C _m H _n (1-1)

  When the partial oxidation reforming reaction POX according to the equation (1-1) is performed and the temperature of the reformer 5 is equal to or higher than a predetermined temperature (for example, about 450 degrees), the above equation (1) is obtained. In addition, the amount of hydrogen supplied to the reformer 5 is increased to control the amount of hydrogen to be increased. The predetermined temperature used in this control is a temperature set in advance as the temperature of the reformer 5 when the temperature of the combustion unit 18 becomes the reference temperature. The reference temperature corresponds to a temperature at which the hydrogen combustion rate is higher than the hydrogen diffusion rate, and is a temperature set in advance by an experiment or the like.

  After a predetermined time has elapsed since the execution of the partial oxidation reforming reaction POX, a gas in which city gas, air and water vapor are mixed in advance is supplied to the reformer 5. At this time, the control unit 210 outputs a signal to a fuel pump, an air blower, a water pump, and the like so as to supply water vapor in addition to city gas and fuel gas including air. FIG. 10 shows the control voltage of the water pump. In the reformer 5, an autothermal reforming reaction ATR in which the partial oxidation reforming reaction POX described above and a steam reforming reaction SR described later are used together proceeds. Since the autothermal reforming reaction ATR is thermally balanced internally, the reaction proceeds in the reformer 5 while being thermally independent. That is, heat generation by the partial oxidation reforming reaction POX is dominant when there is a large amount of oxygen, and heat absorption by the steam reforming reaction SR is dominant when there is a lot of water vapor. At this stage, the initial stage of activation has already passed, and the temperature inside the power generation chamber 16 has been raised to a certain temperature. Therefore, even if the endothermic reaction is dominant, the temperature does not drop significantly. Even if the autothermal reforming reaction ATR proceeds, the combustion reaction continues in the combustion section 18.

  When the reformer temperature sensor 248 detects that the reformer 5 has a temperature capable of steam reforming after a predetermined time has elapsed since the start of the autothermal reforming reaction, a gas in which city gas and steam are mixed in advance Is supplied to the reformer 5. At this time, the controller 210 outputs a signal to the fuel pump, the water pump, etc. and a signal to stop the reformer air blower so as to supply water vapor in addition to the fuel gas containing only the city gas.

  In the reformer 5, the steam reforming reaction SR of the formula (2) proceeds. Since this steam reforming reaction SR is an endothermic reaction, the reaction proceeds while maintaining a heat balance by the combustion heat from the combustion section 18. At this stage, since the power generation chamber 16 has already been heated to a sufficiently high temperature since it is already the final stage of start-up, there is no significant temperature drop even if the endothermic reaction is the main component. Even if the steam reforming reaction SR proceeds, the combustion reaction continues in the combustion section 18.

_{C m H n + m H 2} O → m CO + (n / 2 + m) H 2 (2)

  As described above, the temperature in the power generation chamber 16 is gradually increased by switching the reforming process in accordance with the progress of the combustion process from the ignition process. When the temperature in the power generation chamber 16 and the fuel cell 4 reaches a predetermined power generation temperature lower than the rated temperature at which the fuel cell module 102 is stably operated, the circuit including the fuel cell module 102 is closed. Thereby, the fuel cell module 102 starts power generation, and a current flows through the circuit. Due to the power generation of the fuel cell, the fuel cell 4 itself also generates heat, and the temperature of the fuel cell 4 rises. As a result, the rated temperature at which the fuel cell module 102 is operated becomes, for example, 600 to 800 ° C.

  Thereafter, in order to maintain the rated temperature, fuel gas and air in an amount larger than the amount of fuel gas and air consumed by the fuel battery cell 4 are supplied, and combustion in the power generation chamber 16 is continued. Let During power generation, power generation proceeds with a steam reforming reaction SR with high reforming efficiency. The steam reforming reaction SR itself (strictly speaking) is performed at about 400 ° C. to 800 ° C., but is operated at about 500 ° C. to 700 ° C. in combination with a fuel cell.

  During this power generation, load following operation is executed. In the case of this embodiment, since the rated current is 7 A, when the required current value is smaller than the rated current value, the operation for suppressing the generated current value is set as the load following operation. In the case of the present embodiment, the control unit 210 sets the amount of reformed gas (city gas amount) supplied when the current value is 7 A to 2.8 L / min, and supplies the reformed gas when the current value is 2 A. The gas amount (city gas amount) is 1.5 L / min.

Next, an example of breakage of the fuel cell will be described with reference to FIGS. 11 and 12. FIG. 11 is a photograph showing a peeled piece peeled from the electrode surface, and FIG. 12 is a partial plan view of a fuel cell stack showing a current path short-circuited by the peeled piece.
As shown in FIG. 11, a part of the electrode surface of the electrode layer 48 outside the fuel cell unit 30 is peeled off to become a peeled piece, and this peeled piece contacts the electrode surface of another adjacent fuel cell unit 30. As a result, a part of the current path is short-circuited.
In FIG. 12, a solid line indicates a current path in the fuel cell stack in a normal state, and a broken line indicates a current path in the fuel cell stack when a short circuit occurs due to the peeling piece 110 illustrated in FIG. . The portion X is a short-circuited path, and the voltage drop of the module voltage is generated as the current path is shortened.

  Next, the voltage drop of the fuel cell module when the fuel cell is damaged (when a short circuit occurs) will be described with reference to FIGS. FIG. 13 is a time chart showing a first case in which a short circuit occurs during execution of the start-up mode in the fuel cell device, and then is resolved, and FIG. FIG. 15 is a time chart showing a third case in which a short-circuit occurs during execution of the stop mode and is then eliminated, and FIG. 16 is a fourth case where a short-circuit occurs during execution of the stop mode and is not eliminated thereafter. It is a time chart which shows a case.

  First, as shown in FIG. 13 and FIG. 14, when the start mode of the fuel cell device is executed, the stack temperature Ts (the temperature of the fuel cell stack 90) is burned and partially oxidized by the fuel gas and power generation air. The temperature gradually increases due to the reforming reaction POX, the autothermal reforming reaction ATR, and the steam reforming reaction SR. At this time, in the SOFC, the module voltage also changes corresponding to the stack temperature, so that the module voltage rises in a smooth curve shape. At this time, the power generation air flow rate is constant.

  In the first case shown in FIG. 13, when the fuel cell is damaged (when a short circuit occurs) in this start-up mode, the module voltage drops abruptly by ΔV for the reason described above. In the first case, the voltage drop of the module voltage is temporary, after which the short circuit is resolved and the value returns to a value close to the normal module voltage. Vf is the module voltage immediately before the voltage drop occurs, and Vg is the module voltage at the end of the start mode (= at the start of the power generation mode). As will be described later, in this embodiment, when the module voltage drops, the power generation air flow rate is increased and supplied.

  In the second case shown in FIG. 14, when the fuel cell is damaged (when a short circuit occurs) in the start-up mode, the module voltage drops by ΔV abruptly for the reason described above. In the second case, the voltage drop of the module voltage is maintained as it is because the short circuit is not eliminated, and does not return to the normal module voltage. Similarly, Vf is the module voltage immediately before the voltage drop occurs, and Vg is the module voltage at the end of the start mode (= at the start of the power generation mode). As will be described later, in this embodiment, when the module voltage drops, the power generation air flow rate is increased and supplied.

  Next, as shown in FIGS. 15 and 16, in the stop mode of the fuel cell device, the stack temperature Ts (temperature of the fuel cell stack 90) gradually decreases. At this time, in SOFC, the module voltage also falls in a smooth curve shape corresponding to the stack temperature. At this time, the power generation air flow rate is constant.

  In the third case shown in FIG. 15, when the fuel cell is damaged (when a short circuit occurs) in this stop mode, the module voltage rapidly drops by ΔV due to the above-described reason. In the third case, the voltage drop of the module voltage is temporary, after which the short circuit is resolved and the value returns to a value close to the normal module voltage. Vf is the module voltage immediately before the voltage drop occurs, and Ve is the module voltage at the end of the stop mode. As will be described later, in this embodiment, when the module voltage drops, the power generation air flow rate is increased and supplied.

  In the fourth case shown in FIG. 16, when the fuel cell is damaged in this stop mode (when a short circuit occurs), the module voltage drops by ΔV abruptly for the reason described above. In the fourth case, the voltage drop of the module voltage is maintained as it is because the short circuit is not eliminated, and does not return to the normal module voltage. Similarly, Vf is a module voltage immediately before the voltage drop occurs, and Ve is a module voltage at the end of the stop mode. As will be described later, in this embodiment, when the module voltage drops, the power generation air flow rate is increased and supplied.

Next, the abnormality determination process in the fuel cell apparatus according to the present embodiment will be described with reference to FIG. FIG. 17 is a flowchart showing the contents of the abnormality determination process in the fuel cell apparatus according to the embodiment of the present invention. In FIG. 17, S indicates each step.
In FIG. 17, first, in S1, it is determined whether or not the fuel cell device is in the startup mode. If the start mode is being executed, the process proceeds to S2 to determine whether or not a voltage drop has occurred in the module voltage.

  If a voltage drop has occurred, the process proceeds to S3, and a voltage drop amount ΔV is calculated. Next, the process proceeds to S4, where it is determined whether or not the obtained voltage drop amount ΔV is greater than 0.1 Vf (= 0.1 times the module voltage Vf immediately before the voltage drop occurs). If it is, it is determined that the fuel cell is abnormal (failure), and the process proceeds to S5 to execute movement corresponding control in the start mode (details are shown in FIG. 18).

  As described above, in this embodiment, in the start-up mode, as shown in FIGS. 13 and 14, the module voltage has a characteristic that rises smoothly and smoothly when the fuel cell is normal. On the other hand, when the module voltage drops and this voltage drop amount ΔV exceeds 0.1 Vf, it is determined that the fuel cell is abnormal, and abnormality response control is executed.

  Next, when it is determined in S1 that the start mode is not being executed, the process proceeds to S6 to determine whether or not the stop mode is being executed. Here, when it is determined that the stop mode is not being executed, the power generation mode is being executed. Therefore, in the fuel cell device according to the present embodiment, the abnormality handling control is not performed in this power generation mode.

  If it is determined in S6 that the stop mode is being executed, the process proceeds to S7 to calculate the voltage drop amount ΔV / Δt per unit time of the module voltage. Next, the process proceeds to S8, in which it is determined whether or not the voltage drop amount ΔV / Δt per unit time is larger than the threshold value α. If it is larger, it is determined that the fuel cell is abnormal (failure), Proceeding to S9, abnormality response control in the stop mode (details are shown in FIG. 20) is executed.

In both cases of NO in S2 and NO in S4, the process proceeds to S10 and it is determined whether or not “F2 = 1 or F4 = 1”.
Here, F2 is a flag indicating whether or not there is an execution history of abnormality handling control in the past activation mode, and means that F2 = 0 has no execution history and F2 = 1 has an execution history. F4 is a flag indicating the presence / absence of an execution history of abnormality handling control in the past stop mode. F4 = 0 indicates no execution history, and F4 = 1 indicates that there is an execution history.
F2 = 0 and F4 = 0 are set when the fuel cell device is installed in a home or the like. The values set in the flags F2 and F4 are stored in the control unit 210.
In S10, when “F2 = 1 or F4 = 1”, since abnormality response control has been executed in the past, the process proceeds to S5, regardless of the presence or absence of the voltage drop and the magnitude of the voltage drop at that time. Execute abnormality response control.
In S10, when “F2 = 1 or F4 = 1” is not satisfied, the abnormality handling control is not executed.

  As described above, in the present embodiment, in the stop mode, as shown in FIGS. 15 and 16, if the fuel cell is normal, the module voltage simply has a characteristic of decreasing smoothly. When the voltage drop amount ΔV / Δt of the fuel cell exceeds the threshold value α, it is determined that the fuel cell is abnormal, and abnormality response control is executed. Here, the threshold value α is set based on the module voltage Vf immediately before the voltage drop occurs.

Next, with reference to FIGS. 18 and 19, the abnormality handling control in the start mode will be described. FIG. 18 is a flowchart showing the contents of the abnormality countermeasure control (subroutine of S5 in FIG. 17) in the start-up mode of the fuel cell device according to one embodiment of the present invention, and FIG. 19 shows the fuel cell device according to one embodiment of the present invention. It is a figure which shows the voltage at the time of starting mode completion | finish in the abnormality countermeasure control, the maximum generated current, and the fuel flow rate. In FIG. 18, S indicates each step.
As shown in FIG. 18, first, in S11, it is determined whether or not the voltage drop amount ΔV is larger than 0.2 Vf. In the present embodiment, when the voltage drop amount ΔV exceeds 0.2 Vf, it is considered that the fuel cell is seriously damaged, and the mode is immediately shifted to the stop mode. On the other hand, if the voltage drop amount ΔV is in the range of 0.1 Vf to 0.2 Vf, it is considered that a certain amount of power generation is possible, and the start-up mode is continued. This will be specifically described below.

  When the voltage drop amount ΔV exceeds 0.2 Vf, the process proceeds to S12, and the notification device 216 (see FIG. 9) notifies the failure of the fuel cell. Next, it progresses to S13 and the failure of a fuel cell is displayed on the display apparatus 214 (refer FIG. 9). Furthermore, it progresses to S14, transfers to start mode from stop mode, and stops a fuel cell apparatus.

  On the other hand, when the voltage drop amount ΔV does not exceed 0.2 Vf, that is, when the voltage drop amount ΔV is in the range of 0.1 Vf to 0.2 Vf, the process proceeds to S15, and the notification device 216 causes the fuel cell to be changed. The “cell performance deterioration” is notified, and the process proceeds to S6, where the display device 214 displays “cell performance deterioration”.

  Next, it progresses to S17 and increases and supplies the air flow rate for electric power generation (refer FIG.13 and FIG.14). Thereafter, the process proceeds to S18 to determine whether or not the module voltage has been restored to the normal voltage value. When the module voltage is recovered, the process proceeds to S19, the increase of the power generation air flow rate is stopped, and the process proceeds to S20, where the flag F1 is set to F1 = 1. F1 = 1 indicates a state in which the module voltage is recovered by the end of the start-up mode and the increase in the power generation air flow rate is stopped.

  In the present embodiment, when the voltage drop amount ΔV of the module voltage is in the range of 0.1 Vf to 0.2 Vf, the power generation air flow rate is increased more than when the fuel cell is normal, and the strip (see FIG. 11) is blown away to eliminate the short circuit. As a result, when the voltage recovers, the power generation air flow rate is returned to the normal state.

  Next, it progresses to S21 and it is determined whether start mode is complete | finished, specifically, whether stack temperature has reached power generation start temperature. If the start mode is ended, the process proceeds to S22, and it is determined whether F1 = 1. The case where F1 = 1 is not the case where the short circuit has not been resolved by the end of the start-up mode despite the voltage drop and the increase in the power generation air flow rate (the voltage has not recovered). It advances and stops the increase in the power generation air flow rate (see FIGS. 13 and 14). In the case of F1 = 1, there is already voltage recovery and the increase in the power generation air flow rate is stopped.

  As described above, in the present embodiment, when the stack temperature reaches the power generation start temperature without the short circuit being resolved and the voltage not recovering in spite of the increase in the power generation air flow rate, the start mode is set. finish. Further, the increased air flow rate for power generation is returned to the normal flow rate of the fuel cell.

  Next, in S24, the maximum generated current at the start of the power generation mode is determined based on the voltage Vg at the end of the start mode. As shown in FIG. 19, the maximum generated current at the start of the power generation mode is set to a smaller value as the voltage Vg at the end of the start mode is smaller. Since the voltage at the end of the normal startup mode is about 160V, when Vg is 150V or more, the maximum generated current is set to 7A of the rated current, while when the voltage drop occurs The maximum generated current is set to a value smaller than this rated current value. Further, the fuel flow rate Qo is similarly set to a smaller value as the voltage Vg at the end of the start mode is smaller.

  Next, in S25, F2 = 1 is set. As described above, F2 = 1 indicates that there is an execution history of abnormality handling control in the startup mode.

Next, the abnormality handling control in the stop mode will be described with reference to FIG. FIG. 20 is a flowchart showing the content of the abnormality countermeasure control (subroutine of S9 in FIG. 17) in the stop mode of the fuel cell device according to one embodiment of the present invention. In FIG. 20, S indicates each step.
First, as a premise, since the voltage drop amount ΔV / Δt per unit time exceeds the threshold value α and it is determined that the fuel cell is abnormal, in S31, the notification cell 216 causes the “cell "Performance degradation" is notified, and the process proceeds to S32, and the display device 214 displays "Cell performance degradation".

  Next, the process proceeds to S33, and the power generation air flow rate is increased and supplied (see FIGS. 15 and 16). Thereafter, the process proceeds to S34, in which it is determined whether or not the module voltage has been restored to the normal voltage value. When the module voltage is recovered, the process proceeds to S35, the increase in the power generation air flow rate is stopped, and the process proceeds to S36, where the flag F3 is set to F3 = 1. F3 = 1 indicates a state where the voltage is recovered by the end of the stop mode and the increase in the power generation air flow rate is stopped.

  In the present embodiment, when the voltage drop amount ΔV / Δt per unit time exceeds the threshold value α, the power generation air flow rate is increased more than when the fuel cell is normal, and the separation piece (see FIG. 11). ) Is blown away to eliminate the short circuit. As a result, when the voltage recovers, the power generation air flow rate is returned to the normal state.

  Next, it progresses to S37 and it is determined whether stop mode is complete | finished. If the stop mode is ended, the process proceeds to S38, and it is determined whether or not F3 = 1. If F3 = 1 is not satisfied, the voltage drop occurs and the short circuit is not resolved despite the increase in the power generation air flow rate (the voltage does not recover), so the process proceeds to S39 and the increase in the power generation air flow rate is stopped. (See FIG. 15 and FIG. 16). In the case of F3 = 1, there is already voltage recovery and the increase in the power generation air flow rate is stopped.

  As described above, in this embodiment, when the power generation air flow rate is increased, the start mode is terminated when the short circuit is not eliminated and the voltage does not recover. Further, the increased air flow rate for power generation is returned to the normal flow rate of the fuel cell.

  Next, in S40, F4 = 1 is set. F4 = 1 is a flag indicating that there is an execution history of abnormality handling control in the stop mode.

  Here, when F4 = 1 is set, as shown in FIG. 17, in the startup mode of the operation to be executed next in the fuel cell device, the abnormality handling control has been executed in the past. Proceeding to S5, in the start-up mode, the abnormality handling control is executed regardless of the presence or absence of the voltage drop and the magnitude of the voltage drop amount. In the abnormality handling control in the startup mode, the “maximum generated current” in the subsequent power generation mode is determined (see S25 in FIG. 18).

  As described above, according to the fuel cell device according to the present embodiment, when the voltage drop amount ΔV and / or the voltage drop amount per unit time ΔV / Δt drops by a predetermined amount in the start mode or the stop mode. Since it is determined that the fuel cell is abnormal, the abnormality of the fuel cell can be accurately determined even in the fuel cell device that follows the load. Further, according to the present embodiment, when abnormality of the fuel cell is determined, the abnormality handling control is executed, so that it is possible to execute the operation corresponding to the fuel cell module whose power generation performance is reduced.

  According to the fuel cell device according to the present embodiment, the start mode is shifted to the stop mode or the start mode is continued according to the voltage drop amount of the fuel cell module, that is, according to the degree of damage of the fuel cell. Since such different abnormality handling control is executed, the abnormality handling control suitable for the fuel cell can be executed.

  According to the fuel cell device according to the present embodiment, the abnormality of the fuel cell is continuously determined even after the determination of the abnormality of the fuel cell in the start mode or the stop mode. Even in the case where the module voltage recovers after the determination and the abnormality is resolved, it is possible to reliably detect the breakage of the fuel cell.

  According to the fuel cell device according to the present embodiment, as abnormality response control, the abnormality of the fuel cell is notified and the operation is stopped, so that the user can repair or replace the fuel cell module or the fuel cell. Can be encouraged.

  According to the fuel cell device according to the present embodiment, when the voltage drop amount of the fuel cell module is larger than a predetermined value, that is, when the degree of damage of the fuel cell is large, the operation is stopped and the fuel cell cell If the amount of voltage drop of the fuel cell module is smaller than a predetermined value, that is, if the degree of damage of the fuel cell is small, the power generation performance can be restored by prompting repair or replacement. Power generation can be performed while the performance is reduced.

  According to the fuel cell device according to the present embodiment, when the voltage drop amount of the fuel cell module is smaller than the predetermined value and the operation is continued, the power generation mode executed after that (the fuel cell is abnormal in the stop mode) If it is determined, the maximum power generation amount in the next operation of the fuel cell device (which means “power generation mode” after the start-up mode) is made lower than the maximum power generation amount when the fuel cell is normal. Further, damage to the fuel battery cell caused by power generation can be reduced.

  In the fuel cell device according to the present embodiment, the supply amount of the fuel gas that is the reaction gas or the air for power generation is increased from the supply amount when the fuel cell is normal in the abnormality response control. By using the reacted gas, it is possible to blow away peeling pieces and the like that are short-circuited between the fuel battery cells, thereby eliminating the short-circuit and recovering the voltage.

DESCRIPTION OF SYMBOLS 1 Fuel cell apparatus 4 Fuel cell 5 Reformer 30 Fuel cell unit 90 Fuel cell stack 102 Fuel cell module 104 Auxiliary unit 110 Separation piece 124 Water supply source 128 Water supply unit 130 Fuel supply source 138 Fuel flow rate supply unit 140 Air supply source 144 Air flow rate adjustment unit 154 Inverter 210 Control unit 214 Display device 216 Notification device 226 Power state detection sensor

Claims (7)

In the fuel cell device that can change the power generation amount following the load,
A plurality of solid oxide fuel cells each having an inner electrode layer, an outer electrode layer, and an electrolyte layer disposed between the inner electrode layer and the outer electrode layer are disposed adjacent to each other. A fuel cell module;
A reaction gas supply means for supplying a reaction gas used for a power generation reaction to the fuel cell;
Voltage detection means for detecting a module voltage generated in the fuel cell module;
An activation mode in which the temperature of the fuel cell is raised to a power generation start temperature at which predetermined power can be generated while controlling the amount of reaction gas supplied to the fuel cell by the reaction gas supply means; Control means for executing a power generation mode for outputting electric power from the fuel cell module while following the load,
In the start-up mode, when the voltage drop of the module voltage occurs in the state in which the value of the module voltage is increased with no load in the startup mode, the voltage drop amount of the module voltage has occurred. A fuel cell device characterized in that if the value is greater than a value calculated from the immediately preceding module voltage , the fuel cell is determined to be abnormal, and abnormality response control is executed.   2. The fuel cell device according to claim 1, wherein the control unit executes different abnormality response control according to a voltage drop amount of the fuel cell module.   3. The fuel cell device according to claim 1, wherein the control unit continuously determines the abnormality of the fuel cell after the determination of the abnormality of the fuel cell in the startup mode. 4.   The fuel cell apparatus according to any one of claims 1 to 3, wherein the abnormality handling control by the control means is to notify the abnormality of the fuel cell and stop the operation.   5. The abnormality response control by the control means stops the operation when the voltage drop amount of the fuel cell module is larger than a predetermined value, and continues the operation when the voltage drop amount is smaller than the predetermined value. 2. The fuel cell device according to item 1.   When the voltage drop amount of the fuel cell module is smaller than the predetermined value and the operation is continued, the control means sets the maximum power generation amount in the power generation mode to be executed thereafter to the maximum when the fuel cell is normal. The fuel cell device according to claim 5, wherein the fuel cell device is lower than the power generation amount.   2. The fuel cell apparatus according to claim 1, wherein the abnormality response control of the control means is configured to increase the supply amount of the reaction gas from a supply amount when the fuel cell is normal. 3.