JP6239924B2 - Fuel cell device - Google Patents

Description

  The present invention relates to a technique for alleviating a temperature gradient of a fuel cell assembly in a fuel cell apparatus including a fuel cell assembly that generates power using fuel and an oxidant.

  As a fuel cell device, a device disclosed in Patent Document 1 is such that a heat transfer plate suspended from a reformer above a fuel cell assembly is opposed to the side of the fuel cell, and radiant heat from the fuel cell is transferred to the heat transfer plate. In this way, the temperature of the reformer is raised by transferring heat to the reformer to improve the reforming performance.

  In the device disclosed in Patent Document 2, the temperature gradient of the fuel cell assembly is mitigated by a heat conducting member disposed in contact with the fuel cell. Moreover, what is disclosed by patent document 3 has arrange | positioned the heat conductive member as a partition member which partitions off a some fuel cell, and has aimed at relaxation of the temperature gradient of a fuel cell assembly.

JP 2008-034205 A JP 2011-129280 A JP 2007-157424 A

  However, the thing of patent document 1 aims at the heat transfer to a reformer, and does not relieve the temperature gradient of a fuel cell assembly. In Patent Documents 2 and 3, since the heat conducting member is disposed in contact with the fuel cell, an electrical insulating material is required, and the structure of the heat transfer plate is complicated. In all cases, the temperature gradient in the vertical direction of the fuel cell assembly is taken into consideration, and there is room for improvement in mitigating the temperature gradient of the fuel cell assembly.

  The present invention has been made paying attention to such a conventional problem, and an object of the present invention is to provide a fuel cell device that can alleviate the temperature gradient of the fuel cell assembly.

In order to achieve the above object, the present invention provides:
A fuel cell assembly;
A heat transfer plate partially facing the side surface of the fuel cell assembly;
A reformer whose reforming method is a steam reforming reaction ,
The side portion of the fuel cell assembly has a temperature gradient during power generation,
The reformer is connected to a raw fuel supply pipe for supplying raw fuel to one end in the front-rear direction of the fuel cell assembly.
In the heat transfer plate, a portion facing a relatively high temperature region in the fuel cell assembly and a portion facing a relatively low temperature region in the fuel cell assembly are continuous , And in the side view, the area on the upper side and the side where the raw fuel supply pipe is not connected is larger than the area on the upper side where the raw fuel supply pipe is connected .

  According to the present invention, the heat in the relatively high temperature region in the fuel cell assembly is transferred by radiation to the heat transfer plate partially facing the fuel cell assembly, and the heat in the fuel cell assembly is relatively It is transmitted by radiation from the heat transfer plate to a low temperature region. Thereby, the temperature of a high temperature area | region can be reduced, the temperature of a low temperature area | region can be raised, and the temperature gradient of a fuel cell assembly can be relieve | moderated.

It is a longitudinal cross-sectional view which shows the basic structure of the principal part of the solid oxide fuel cell apparatus which concerns on 1st Embodiment of this invention. It is XX sectional drawing of FIG. Drawing 3 (a)-(c) is a figure showing the modification of the heat exchanger plate concerning a 1st embodiment. FIGS. 6A to 6F are diagrams showing other modified examples of the heat transfer plate according to the first embodiment. It is a longitudinal cross-sectional view which shows the basic structure of the waist | lumbar part of the solid oxide fuel cell apparatus which concerns on 2nd Embodiment of this invention. FIGS. 8A and 8B are views showing a modification of the heat transfer plate according to the second embodiment.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 show the basic structure of the main part (power generation chamber) of the solid oxide fuel cell device according to the first embodiment of the present invention. A fuel cell assembly 11a that generates power using a hydrogen-enriched gas and an oxidizing agent is provided inside the frame 1 that surrounds the main part of the apparatus.

  In the fuel cell assembly 11a, a plurality of solid oxide fuel cells formed by stacking an anode (fuel electrode) and a cathode (oxidant electrode) on both surfaces of an electrolyte made of a solid oxide are electrically connected in series and / or Or connected in parallel. The lower end portion of the fuel cell assembly 11a is supported by the pedestal 11b. In the present embodiment, the base 11b that supports the fuel battery cell 11a functions as a manifold portion. Since the shape and arrangement of the solid oxide fuel cells can be arbitrarily selected, the fuel cell assembly 11a in the figure is schematically shown by omitting them.

  A reformer 12 is provided above the fuel cell assembly 11a, and the reformer 12 reforms the hydrogen-containing fuel supplied from the raw fuel supply pipe 15 to generate a hydrogen-enriched gas. . The reforming method in the reformer 12 is not particularly limited, and for example, steam reforming, partial oxidation reforming, autothermal reforming, and other reforming methods can be employed. When steam reforming is used, a water vaporization unit is provided in the reformer 12 (or separately from the reformer 12), and steam supplied from the outside of the frame 1 is heated and vaporized to generate steam. . As the hydrogen-containing fuel (raw fuel), for example, a hydrocarbon fuel is used. As the hydrocarbon fuel, a compound containing carbon and hydrogen in its molecule (which may contain other elements such as oxygen) or a mixture thereof is used. For example, hydrocarbons, alcohols, ethers And biofuels. Specific examples of hydrocarbons include methane, ethane, propane, butane, natural gas, LPG (liquefied petroleum gas), city gas, town gas, gasoline, naphtha, kerosene, and light oil. Examples of alcohols include methanol and ethanol. Examples of ethers include dimethyl ether. Examples of biofuels include biogas, bioethanol, biodiesel, and biojet.

  The hydrogen-enriched gas is supplied into the pedestal 11b through the hydrogen-enriched gas supply pipe 16, and is supplied to each anode of the fuel cell assembly 11a. An oxidant is supplied to the cathode (oxidant electrode) of the fuel cell assembly 11a. Hydrogen-enriched gas and oxidant (hereinafter referred to as off-gas) that have not contributed to the power generation of the fuel cell assembly 11a are burned in the off-gas combustion section 21 between the fuel cell assembly 11a and the reformer 12. Is done. Between the frame body 1 and the fuel cell assembly 11a, a heat insulating material 13 that suppresses heat radiation to the outside of the frame body 1 is disposed. Thereby, the inside of the frame 1 is maintained in a high temperature state, and the power generation of the fuel cell assembly 11a is performed. Further, the reformer 12 is maintained at a temperature necessary for generating the hydrogen-enriched gas. Exhaust gas generated by off-gas combustion is discharged outside the solid oxide fuel cell device via an exhaust gas passage (not shown) outside the frame 1.

  In such a basic structure of the fuel cell device, a position between the heat insulating material 13 and the fuel cell assembly 11a partially faces the side surface of the fuel cell assembly 11a and does not contact the fuel cell assembly 11a. A heat transfer section (heat transfer plate) 14 is provided.

  Here, the fuel cell assembly 11a generates heat by power generation and rises in temperature throughout, but the upper side is closer to the off-gas combustion unit 21, and thus the temperature is higher, whereas the lower side is hydrogen-rich. Since it corresponds to the upstream position of the flow of the chemical gas and the oxidant, the temperature is lower than that on the upper side. In addition, the lower side of the fuel cell assembly 11a is a non-heating element and is connected to a metal base 11b having a large heat capacity. This also compares with the upper side of the fuel cell assembly 11a. It becomes low temperature. Further, the upper end portion of the fuel cell assembly 11a has a lower temperature than the central portion on the upper side of the fuel cell assembly 11a that is difficult to dissipate heat due to heat dissipation from both end faces. The temperature gradient, when viewed from either side, is broadly divided into a high temperature region at the upper center, an intermediate temperature region at both upper ends, and a low temperature region at the lower side. Furthermore, the vicinity of the raw fuel supply pipe 15 and the hydrogen-enriched gas supply pipe 16 to which the raw fuel is supplied from the outside of the frame body 1 is at a lower temperature than the central portion. That is, the temperature gradient of the surface temperature of the fuel cell assembly 11a during power generation is affected even by the layout of various components arranged in the frame 1.

  The heat transfer section 14 does not face a part of the upper end portions (intermediate temperature region) of the upper side of the fuel cell assembly 11a, but extends from the center portion (high temperature region) on the upper side of the fuel cell assembly 11a to the lower side (low temperature region). ) In the form of continuous opposition. Specifically, the fuel cell assembly 11a corresponding to the high temperature region is continuously inclined from the center of the upper side to the lower side corresponding to the low temperature region. The heat of the surface of the fuel cell assembly 11a is transferred from the upper center portion (high temperature region) to the lower side (low temperature region) of the fuel cell assembly 11a via the heat transfer section 14 by radiant heat transfer. . Thereby, the heat in the high temperature region of the fuel cell assembly 11a is transferred to the low temperature region in preference to the heat in the intermediate temperature region, and the temperature gradient between the high temperature region and the low temperature region of the fuel cell assembly 11a is increased. Alleviated. The heat transfer unit 14 may be disposed to face a plurality of surfaces of the fuel cell assembly 11a, or may be disposed to face only one side surface. Furthermore, the heat transfer section 14 facing the same surface of the fuel cell assembly 11a may be divided into a plurality of parts.

  The height of the heat transfer section 14 is preferably lower than the bottom height of the reformer 12. Since the raw fuel is supplied to the reformer 12 from the outside of the fuel cell device, the reformer 12 tends to have a lower temperature than the high temperature region of the fuel cell assembly 11a. In particular, when the reforming method in the reformer 12 is a steam reforming reaction (endothermic reaction), the endothermic amount from the periphery of the reformer 12 is large. Therefore, by setting the height of the heat transfer section 14 lower than the bottom of the reformer 12, it is possible to effectively transfer heat from the high temperature region to the low temperature region of the fuel cell assembly 11a. In particular, it is more preferable that the height H1 of the heat transfer section 14 is substantially equal to the height H2 of the fuel cell assembly 11a. The heat transfer unit 14 can receive the radiant heat from the high temperature region of the fuel cell assembly 11a to the maximum extent. As a result, the amount of heat supplied to the lower side of the fuel cell assembly 11a can be increased as much as possible to promote the temperature rise on the lower side of the fuel cell assembly 11a, and consequently the fuel cell assembly 11a. The temperature gradient can be relaxed. In addition, by suppressing the heat transfer in the intermediate temperature region and transferring the heat from the high temperature region to the low temperature region, the upper and lower temperatures approach the intermediate temperature, respectively, thereby suppressing the temperature gradient in the front-rear direction. it can.

<Modification 1-1>
The shape of the heat transfer section 14 is not limited to the shape shown in FIG. For example, as shown to Fig.3 (a), you may make it have a level | step difference (step shape) instead of an inclination over the high temperature area | region and low temperature area | region of the fuel cell assembly 11a. Further, as shown in FIG. 3B, the step and the inclination may be continued by a combination. These are preferably arbitrarily shaped according to the temperature gradient tendency of the fuel cell assembly 11a during power generation. Moreover, as shown in FIG.3 (c), you may equip a part of heat-transfer part 14 with the opening part 14c. According to this, the strength of the heat transfer section 14 can be maintained. In addition, the shape of each side and the corner | angular part process of the heat-transfer part 14 are not limited to a straight line, You may make it continue with a curve.

<Modification 1-2>
The temperature gradient on the lower side of the fuel cell assembly 11a tends to be lower at both ends than at the center. That is, the lower center of the fuel cell assembly 11a may be roughly divided into an intermediate temperature region. Therefore, as shown in FIGS. 4A to 4F, the lower ends of the fuel cell assembly 11a and the heat transfer section 14 are opposed to each other, and the lower central portion of the fuel cell assembly 11a is transmitted. You may make the thermal part 14 non-opposing. Thereby, the heat | fever of a high temperature area | region can be preferentially transmitted to the lower both ends of the fuel cell assembly 11a. For example, when the temperature of the fuel cell assembly 11a tends to be lower at the end where the hydrogen-enriched gas supply pipe 16 is disposed than at the other end, the non-opposing portion is unevenly distributed at the other end side, The heat transfer area at the end on which the enriched gas supply pipe 16 is disposed may be increased.

  The heat transfer section 14 may be erected on the pedestal 11b in addition to being erected on the heat insulating material 13 disposed on the lower side of the fuel cell assembly 11a. Moreover, as shown in FIG. 1, the 1st heat-transfer part 14a which bends the downward direction of the heat-transfer part 14, and opposes the fuel cell assembly 11a, and the 2nd heat-transfer part 14b which contacts the base 11b, It may be formed including. Thereby, the installation stability of heat-transfer part 14 itself can be improved. Further, the heat received by radiation from the high temperature region of the fuel cell assembly 11a can be transferred from the end of the second heat transfer portion 14b to the pedestal 11b, and the temperature of the pedestal 11b can be raised. Increasing the temperature of the pedestal 11b itself leads to an increase in the lower temperature of the fuel cell assembly 11a. Thereby, the temperature gradient of the high temperature area | region and low temperature area | region of the fuel cell assembly 11a can be relieve | moderated.

[Second Embodiment]
5 and 6 show a second embodiment according to the present invention. Note that description of matters common to the first embodiment is omitted.

In the second embodiment, the heat transfer section 14 is disposed on both side surfaces with the fuel cell assembly 11a interposed therebetween. In FIG. 5, the height of the heat transfer section 14L disposed on the left side (hereinafter simply referred to as the left side) of the fuel cell assembly 11a is H1, the height of the fuel cell assembly 11a is H2, and the fuel cell assembly 11a. The height of the heat transfer section 14R disposed on the right side (hereinafter simply referred to as the right side) is H3. For example, when the temperature gradient on the left side surface of the fuel cell assembly 11a is larger than the temperature gradient on the right side surface, the shape of the heat transfer section 14 is set as shown in the following equation (1).
H1≈H3> H2 (1)
In this way, the amount of heat transferred from the high temperature portion on the left side surface of the fuel cell assembly 11a having a relatively large temperature gradient to the low temperature portion via radiation from the heat transfer portion 14L is relatively low. Is larger than the amount of heat transferred from the high temperature portion of the right side surface of the fuel cell assembly 11a to the low temperature portion through radiation to the heat transfer section 14R, and therefore the temperature gradient in the left-right direction of the fuel cell assembly 11a is also Can be relaxed.
Thus, the amount of radiant heat between the fuel cell assembly 11a and the heat transfer section 14 is adjusted by changing the height of the heat transfer section 14 according to the temperature gradient on each side of the fuel cell assembly 11a. Is preferred.

<Modification 2-1>
Further, as shown in FIG. 6, the lengths L1a, L1b, L2a, L2b are defined as follows in the longitudinal direction of the heat transfer portions 14L, 14R, and the relationship between these lengths is set as described below. .
L1a: In the left heat transfer section 14L, from the point O1 where the two straight lines connecting the ends of the upper side to the ends on the opposite side of the base (hereinafter also referred to as intersections) O1, the front side in the figure (hereinafter simply referred to as the front side) ) L1b: Similarly, the distance from the intersecting point O1 to the rear side in the figure (hereinafter simply referred to as the rear side) L2a: In the right heat transfer section 14R, each end of the upper side is connected to the bottom side Distance from the point O2 at which the two straight lines connecting the opposite ends cross to the front side L2b: Similarly, the distance from the crossing point O2 to the rear side

When the raw fuel supply pipe 15 to the reformer 12 is connected to the front side of the reformer 12, the shape of the heat transfer section 14 is set as shown in the following equation (2).
L1a> L1b or / and L2a> L2b (2)
When the reforming method in the reformer 12 is a steam reforming reaction (endothermic reaction), the endothermic amount from the periphery of the reformer 12 is large. In particular, the end on the side to which the raw fuel supply pipe 15 is connected preferentially undergoes an endothermic reaction as compared with the other end, so that the endothermic amount is large. Therefore, the front side of the fuel cell assembly 11a tends to be lower in temperature than the rear side of the fuel cell assembly 11a. Under the influence, the position of the high temperature region of the fuel cell assembly 11a is unevenly distributed on the rear side. Therefore, by setting the shape of the heat transfer section 14 so as to have the relationship as expressed by the above formula (1), the amount of radiant heat from a portion having a relatively low temperature is reduced, and the radiant heat from a portion having a relatively high temperature is reduced. It can be transmitted to the lower side of the fuel cell assembly 11a. Thereby, not only the temperature gradient in the vertical direction of the fuel cell assembly 11a but also the temperature gradient in the front-rear direction can be relaxed.

<Modification 2-2>
When the raw fuel supply pipe 15 to the reformer 12 is connected to the front side and the right side of the reformer 12, the shape of the heat transfer section 14 is set as shown in the following equation (3).
1> L1b / L1a> L2b / L2a (3)
The front side of the reformer 12 on the front side of the fuel cell assembly 11a tends to be cooler on the right side than on the left side. Therefore, the distances L1a and L2a to the front end face are made larger than the distances L1b and L2b to the rear end face, and the distance L1a from the intersection O2 of the heat transfer section 14R to the front end face is set to the distance L1a of the heat transfer section 14L. The distance is greater than the distance L1b from the intersection O1 to the rear end face.

  Thereby, the radiation efficiency to the heat-transfer parts 14L and 14R from each high temperature area | region of the left side part and the right side part of the fuel cell assembly 11a can be improved. As a result, the temperature gradient in the left-right direction and the front-rear direction of the fuel cell assembly 11a can be relaxed.

<Modification 2-3>
Further, the areas A1a, A1b, A2a, A2b of the respective portions of the heat transfer portions 14L, 14R shown in FIGS. 6A and 6B are defined as follows.
A1a: In the heat transfer section 14L, an area on the front side with respect to the vertical line X1 in the vertical direction passing through the intersecting point O1 intersects two straight lines connecting the ends of the upper side to the ends on the opposite side of the bottom side, respectively. : Similarly, the area on the rear side with respect to the vertical line X1 in the vertical direction passing through the intersecting point O1. A2a: In the heat transfer section 14R, the two straight lines connecting the respective ends of the upper side with the respective ends on the opposite side of the bottom side are intersected. The area on the front side with respect to the vertical line X2 in the vertical direction passing through the intersecting point O2 A2b: Similarly, the area on the rear side with respect to the vertical line X2 in the vertical direction passing through the intersecting point O2 is transmitted using these areas. You may set the shape of the heat | fever part 14 like following (4) Formula.
A1a> A1b and A2a> A2b (4)
Thereby, it can be efficiently radiated from the high temperature region of the fuel cell assembly 11a unevenly distributed on the side opposite to the side to which the raw fuel supply 15 is connected to the heat transfer section 14, and the temperature of the fuel cell assembly 11a The slope can be relaxed.

Moreover, when the heat absorption part of the reformer 12 is unevenly distributed on the front side and the right side, the following formula (5) is added to the above formula (4).
<Modification 2-4>
A1a> A1b and A2a> A2b (4)
A1a> A2a or A2a> A2b (5)
If it does in this way, the heat-transfer parts 14L and 14R which oppose each can be brought close to the position of the high temperature area | region which is different in the left side part and right side part of the fuel cell assembly 11a. As a result, the temperature gradient in the up-down direction, the left-right direction, and the front-rear direction of the fuel cell assembly 11a can also be reduced. The “case where the heat absorption part of the reformer 12 is unevenly distributed on the front side and the right side” includes, for example, a case where the internal flow path of the reformer 12 has a folded structure.

  In addition, in 2nd Embodiment, the structure which has arrange | positioned the 2nd heat-transfer part 14b in the heat-transfer part 14 between the heat insulating material 13 arrange | positioned under the fuel cell assembly 11a, and the base 11b. Indicated. Thereby, the heat transfer area from the 2nd heat-transfer part 14b to the base 11b can be ensured large. As a result, it contributes to an increase in the lower temperature of the fuel cell assembly 11a, and the temperature gradient of the fuel cell assembly 11a can be effectively reduced. Further, the installation stability of the heat transfer section 14 itself can be further enhanced. In addition, you may apply the heat transfer part 14 of the said shape to 1st Embodiment, or may apply the heat transfer part 14 of 1st Embodiment to 2nd Embodiment.

  The illustrated embodiments are merely examples of the present invention, and the present invention includes various improvements and modifications made by those skilled in the art within the scope of the claims in addition to those directly shown by the described embodiments. It goes without saying that it is what you do. For example, you may insert the heat-transfer part 14 in the clearance gap between the some solid oxide fuel cell which comprises the fuel cell assembly 11a. Further, in order to suppress deformation of the heat transfer section 14, the heat transfer section 14 may be processed to be concave or convex. Alternatively, in order to suppress contact between the heat transfer section 14 and the fuel cell assembly 11a or to form a flow path for the oxidant, a partial insulation is provided between the heat transfer section 14 and the fuel cell assembly 11a. A member may be interposed.

  Further, the reformer 12 may not be provided inside the frame body 1. For example, there is a form in which a reformer is provided outside the frame 1 and the hydrogen-enriched gas generated therein is supplied from the fuel supply pipe to the fuel cell assembly 11a. Alternatively, instead of the reformer, the fuel supply pipe is provided with a dehydrogenation reaction section and a dehydrogenation discharge pipe for discharging the dehydrogenation product from the dehydrogenation reaction section between the fuel supply pipe and the fuel cell assembly. There is a form in which an organic hydride that occludes hydrogen is supplied to the dehydrogenation reaction section, and a hydrogen-rich gas generated by the dehydrogenation reaction is supplied to the fuel cell assembly. Alternatively, there is a form in which hydrogen-rich gas is supplied to the hydrogen-enriched gas supply pipe 16 from the outside of the solid oxide fuel cell device.

DESCRIPTION OF SYMBOLS 1 ... Frame 11a ... Fuel cell assembly 11b ... Base 12 ... Reformer 14, 14L, 14R ... Heat transfer part 14a ... 1st heat transfer part 14b ... 2nd heat transfer part 21 ... Off-gas combustion part

Claims (8)

A fuel cell assembly;
A heat transfer plate partially facing the side surface of the fuel cell assembly;
A reformer whose reforming method is a steam reforming reaction ,
The side portion of the fuel cell assembly has a temperature gradient during power generation,
The reformer is connected to a raw fuel supply pipe for supplying raw fuel to one end in the front-rear direction of the fuel cell assembly.
In the heat transfer plate, a portion facing a relatively high temperature region in the fuel cell assembly and a portion facing a relatively low temperature region in the fuel cell assembly are continuous , The fuel cell device has a shape in which the area on the upper side and the side where the raw fuel supply pipe is not connected is larger than the area on the upper side where the raw fuel supply pipe is connected in side view .   The fuel cell device according to claim 1, wherein the heat transfer plate does not face at least a part of a relatively medium temperature region in the fuel cell assembly. A pedestal that supports the lower end of the fuel cell assembly;
The heat transfer plate includes at least a first heat transfer portion that faces a side surface of the fuel cell assembly, and a second heat transfer portion that is connected to the first heat transfer portion and contacts the pedestal. The fuel cell device according to claim 1 or 2.   The fuel cell device according to claim 3, wherein the second heat transfer portion of the heat transfer plate is in contact with the bottom of the pedestal.   The fuel cell device according to any one of claims 1 to 4, wherein the heat transfer plate has a shape in which a height gradually decreases from an upper central portion toward an end.   The fuel cell device according to any one of claims 1 to 4, wherein the heat transfer plate has a shape in which a height of an end portion is lower than a height of an upper central portion and has a step.   The fuel cell device according to any one of claims 1 to 4, wherein the heat transfer plate has a shape having an opening at an upper end. 8. The fuel cell device according to claim 1, wherein the heat transfer plate has a portion that does not oppose a side surface of the fuel cell assembly in a lower central portion.