JP2015130318A - fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell device capable of reducing the temperature difference between an end side and an intermediate stage side of a fuel cell stack.SOLUTION: A fuel reformer 44 is arranged to face a lamination surface 10a extending in a lamination direction of a power generation cell 100 in a fuel cell stack 10 so that heat can be transferred to the fuel cell stack 10. Further, a reforming catalyst 443 is arranged so that a reforming reaction accompanying endotherm can be accelerated most at an intermediate stage facing site 44B facing an intermediate stage 10B in a lamination direction of the fuel cell stack 10 in the fuel reformer 44.

Description

  The present invention relates to a fuel cell device including a fuel cell stack and a fuel reformer.

  Conventionally, solid oxide fuel cells (SOFCs) and molten carbonate fuel cells (MCFCs) are used as high-temperature fuel cell stacks that operate at high temperatures (eg, 500 ° C or higher). Exists. In this type of high-temperature fuel cell stack, the higher the operating temperature during power generation, the more advantageous from the viewpoint of power generation efficiency.

  However, in the fuel cell stack, the heat radiation at both ends in the stacking direction becomes more conspicuous than in the middle stage in the stacking direction, and the temperature at both ends in the stacking direction tends to be lower than in the middle stage in the stacking direction. When the stacking direction of the fuel cell stack is the vertical direction, the upper end side in the stacking direction tends to be higher than the lower end side in the stacking direction due to the influence of natural convection (temperature distribution: middle stage> upper end). > Lower end).

  Since the power generation efficiency of the fuel cell stack at a low temperature is lower than that at the high temperature, there is a problem that the power generation efficiency of the entire fuel cell stack is reduced.

  On the other hand, a configuration has been proposed in which a fuel reformer for reforming a fuel gas (reforming raw material) such as city gas into a hydrogen-rich fuel gas is disposed close to the height direction of the fuel cell stack ( For example, see Patent Document 1).

  In this patent document 1, the fuel reformer arranged close to the height direction of the fuel cell stack is configured to introduce reformed raw material (unreformed fuel gas) from the upper end side. According to this, since the endothermic amount at the time of the steam reforming reaction (SR) in the fuel reformer becomes the highest at the upper end portion side where the unreformed fuel gas is introduced, due to the endotherm in the fuel reformer, It is possible to lower the temperature mainly on the upper end side in the stacking direction of the fuel cell stack. As a result, the temperature difference between the upper end portion and the lower end portion in the stacking direction of the fuel cell stack can be reduced.

  Patent Document 2 proposes a configuration in which a fuel reformer is disposed on the upper side of the fuel cell stack with the stacking direction of the fuel cell stack as a horizontal direction.

  In Patent Document 2, the fuel reformer is configured such that fuel gas flows in the stacking direction of the fuel cell stack. The reforming reaction of the fuel gas in the fuel reformer is switched in the order of partial oxidation reforming reaction (POX) → autothermal reforming reaction (ATR) → steam reforming reaction (SR). The fuel reformer is heated from the outside by the combustion heat of off-gas from the fuel cell.

JP 2007-157480 A JP 2012-79487 A

  By the way, according to the technique disclosed in Patent Document 1, although the temperature difference at both ends of the fuel cell stack can be reduced, the temperature on the middle stage side in the fuel cell stack is higher than that on the end side of the fuel cell stack. There is still room for improvement because of the high price.

  Further, according to the study by the present inventors, when the partial oxidation reforming reaction (POX) is performed by the fuel reformer in the technique disclosed in Patent Document 2, the temperature characteristics shown in FIG. In addition, in the fuel reformer, an exothermic region, an endothermic region, and an equilibrium region are formed from the inlet side to the outlet side in the fuel gas flow direction. For this reason, the temperature in the fuel reformer becomes higher on the inlet side in the flow direction of the fuel gas.

  Here, in the heat generation region, combustion of the fuel gas shown in the reaction formulas [F7] and [F6] occurs, so heat is generated. The reaction ratio of [F7] and [F6] varies depending on the catalyst. The Ni-based catalyst mainly produces complete combustion [F7] and generates a large amount of heat. In a noble metal catalyst such as Rh, a relatively large amount of partial oxidation [F6] is generated and the temperature rise tends to be somewhat suppressed.

  Oxygen in the reaction formulas [F7] and [F6] is consumed, and in the subsequent endothermic region, the water vapor and the fuel gas generated by the reaction in the reaction formula [F7] perform the endothermic reaction in the reaction formula [F5]. Arise. Then, it shifts to an equilibrium region where the reaction is stable. In this equilibrium region, reaction of reaction formulas [F5], [F6], and [F8], which are reversible reactions, proceed with a change in temperature, resulting in an equilibrium state.

CH ₄ + H ₂ 2O⇔CO + 3H ₂ −206 kJ / mol ... [F5]
CH ₄ + 1 / 2O ₂ ⇔CO + 2H ₂ +36 kJ / mol ... [F6]
CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O + 890 kJ / mol ... [F7]
CO + H ₂ O⇔CO ₂ + H ₂ −41 kJ / mol ... [F8]
Thus, in the fuel gas in the fuel reformer, the heat generation region, the heat absorption region, and the equilibrium region are formed in order from the flow direction inlet side to the outlet side. This increases the temperature on the inlet side in the flow direction of the fuel gas in the fuel reformer. That is, a heat spot is generated at a high temperature on the inlet side in the fuel reformer. For this reason, when the inlet side of the fuel reformer faces one end side in the stacking direction of the fuel cell stack, one end side in the stacking direction of the fuel cell stack becomes the middle stage side due to the heat generated from the fuel reformer. And higher than the other end. For this reason, thermal damage and thermal degradation occur at the high temperature portion of the fuel cell stack.

  An object of the present invention is to provide a fuel cell device in which temperature distribution in a fuel cell stack is made uniform.

  The present invention relates to a fuel cell stack (10) configured by laminating a plurality of power generation cells (100) that output electric energy by an electrochemical reaction between an oxidant gas and a fuel gas, and a hydrocarbon-based reforming raw material. The fuel cell apparatus includes a fuel reformer (44) in which a reforming catalyst (443) for generating a fuel gas to be reformed and introduced into the fuel cell stack is filled.

  In order to achieve the above object, in the first aspect of the present invention, the fuel reformer has a stacking surface (10a) extending in the stacking direction of the power generation cells in the fuel cell stack so that heat can be transferred to the fuel cell stack. And the reforming reaction with heat generation is most promoted at the middle stage facing part (44B) facing the middle stage part (10B) in the stacking direction of the fuel cell stack. It is a feature.

  According to this, the amount of heat generated by the reforming reaction of the fuel reformer is highest at the middle stage facing the middle stage in the fuel cell stack, so that the middle stage of the fuel cell stack is generated by the heat generation in the fuel reformer. The temperature on the part side can be increased. For this reason, in the fuel cell stack, heat is transmitted from the middle stage side to the one end side and the other end side in the stacking direction.

  Therefore, according to the fuel cell device of the present invention, the temperature difference between the one end portion side and the other end portion side in the stacking direction of the fuel cell stack can be reduced, and the temperature distribution in the fuel cell stack can be made uniform. .

  In addition, the fuel reformer of Patent Document 2 generates a reforming reaction that generates heat by itself and is heated from the outside by off-gas combustion heat, so that the inside of the fuel reformer is overheated, and the inside of the fuel reformer If the temperature exceeds the heat resistance temperature of the catalyst, the catalyst may deteriorate.

  On the other hand, according to the first aspect of the present invention, it is possible to cool the middle stage confronting part of the fuel reformer by the middle stage part in the fuel cell stack. Therefore, since it is possible to suppress the inside of the fuel reformer from being overheated, deterioration of the catalyst can be suppressed in advance.

  In the invention according to claim 8, the fuel reformer is arranged to face the stacking surface (10a) extending in the stacking direction of the power generation cells in the fuel cell stack so as to be able to transfer heat with the fuel cell stack. In addition, the reforming reaction with endotherm is most promoted in the middle-stage facing portion (44B) facing the middle-stage portion (10B) in the stacking direction of the fuel cell stack.

  According to this, the endothermic amount due to the reforming reaction of the fuel reformer is highest at the middle stage confronting part facing the middle stage part that tends to become high temperature due to heat generated by the power generation in the fuel cell stack. Thus, the temperature on the middle stage side of the fuel cell stack can be lowered.

  Therefore, according to the fuel cell device of the present invention, it is possible to reduce the temperature difference between the end side and the middle stage side in the stacking direction of the fuel cell stack and make the temperature distribution in the fuel cell stack uniform.

  In addition, the code | symbol in the parenthesis of each means described in this column and the claim shows an example of a correspondence relationship with the specific means described in the embodiment described later.

1 is an overall configuration diagram of a fuel cell system according to a first embodiment. It is a lineblock diagram showing the fuel cell device concerning a 1st embodiment. It is a block diagram which shows the structure of the fuel reformer which concerns on 1st Embodiment. It is a figure which shows the temperature distribution of the fuel reformer which concerns on 1st Embodiment. It is a characteristic view which shows the temperature distribution of the fuel reformer and fuel cell stack which concern on a comparative example. It is a characteristic view which shows the temperature distribution of the fuel reformer and fuel cell stack which concern on 1st Embodiment. It is a block diagram which shows the structure of the fuel reformer which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the fuel reformer which concerns on 3rd Embodiment. It is a block diagram which shows the structure of the fuel reformer which concerns on 4th Embodiment. It is a block diagram which shows the structure of the fuel reformer which concerns on the modification of 4th Embodiment. It is a whole block diagram of the fuel cell system which concerns on 5th Embodiment. It is a block diagram which shows the structure of the fuel reformer which concerns on 5th Embodiment. It is a characteristic view which shows the temperature distribution of the fuel reformer which concerns on a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings. Note that, in each of the following embodiments, parts that are the same as or equivalent to the matters described in the preceding embodiment are denoted by the same reference numerals, and the description thereof may be omitted. Moreover, in each embodiment, when only a part of the component is described, the component described in the preceding embodiment can be applied to the other part of the component.

(First embodiment)
In this embodiment, the fuel cell device 1 of the present invention is applied to the fuel cell system shown in FIG. The fuel cell device 1 of the present embodiment includes a heat-insulating housing 2, a fuel cell stack 10 accommodated in the housing 2, a second air preheater 34 and a fuel reformer 44 described later. . A specific form inside the housing 2 of the fuel cell device 1 will be described later.

  The fuel cell stack 10 includes a plurality of power generation cells 100 that output electric energy by an electrochemical reaction between a fuel gas and an oxidant gas (air in this embodiment), and a flow path for the fuel gas and the oxidant gas. It is a laminated body laminated via separators 14 and 15.

  The fuel cell stack 10 of the present embodiment is composed of a solid oxide fuel cell (SOFC) whose operating temperature is high (for example, 500 ° C. to 1000 ° C.). For convenience of explanation, in FIG. 1, the fuel cell stack 10 is illustrated as a single power generation cell 100.

The power generation cell 100 according to the present embodiment is a flat cell, and includes a solid electrolyte body 11, an air electrode (cathode) 12, and a fuel electrode (anode) 13. Note that the power generation cell 100 of this embodiment uses a reformed gas (H ₂ , CO) obtained by reforming methane gas (CH ₄ ), which is a hydrocarbon-based reforming raw material, as a fuel gas.

  The separators 14 and 15 function as means for electrically connecting the power generation cells 100 and supplying reaction gas such as fuel gas and oxidant gas to the power generation cells 100. The separators 14 and 15 are formed with a fuel gas passage (not shown) for supplying fuel gas to each power generation cell 100 and an air passage (not shown) for supplying air to each power generation cell 100.

  In the fuel cell stack 10 of the present embodiment, exhaust air and exhaust fuel from each power generation cell 100 are exhausted to an air exhaust path 6a and a fuel exhaust path 6b described later via a manifold (not shown).

In each power generation cell 100, electric energy is output by an electrochemical reaction of hydrogen and oxygen represented by the following reaction formulas [F1] and [F2].
(Fuel electrode) 2H ₂ + 2O ²⁻ → 2H ₂ O + 4e ⁻ ... [F1]
(Air electrode) O ₂ + 4e ⁻ → 2O ²⁻ … [F2]
In each power generation cell 100, electric energy is output by an electrochemical reaction of carbon monoxide (CO) and oxygen shown in the following reaction formulas [F3] and [F4].
(Fuel _{^{electrode) 2CO + 2O 2- → 2CO 2}} + 4e - ... [F3]
(Air electrode) O ₂ + 4e ⁻ → 2O ²⁻ … [F4]
An air supply path 3, which is a supply path for power generation air, is connected to the air inlet side of the fuel cell stack 10. In this air supply path 3, an air filter 31 that removes dust and the like, an air blower 32 that pumps power generation air to the fuel cell stack 10, an air preheater 33, and air in order from the upstream side of the air flow A preheater 34 is provided.

  Each air preheater 33, 34 reduces the temperature difference between the power generation air supplied to the air electrode 12 of the fuel cell stack 10 and the high-temperature fuel gas supplied to the fuel electrode 13, thereby generating power in each power generation cell 100. It is provided to improve efficiency.

  The first air preheater 33 heats the power generation air pumped from the air blower 32 by exchanging heat with combustion gas generated by an off-gas combustor 61 described later. The first air preheater 33 exchanges heat between the power generation air pumped from the air blower 32 and the combustion gas having a temperature lower than the temperature of the fuel cell stack 10 during power generation (for example, 700 ° C. to 800 ° C.). This is a low temperature preheater.

  Note that the first air preheater 33 is preferably configured so that the temperature of the air in the first air preheater 33 rises to a temperature equivalent to the fuel gas flowing into the fuel reformer 44 described later. According to this, the temperature of the heat exchange medium flowing into the second air preheater 34 and the fuel reformer 44 arranged around the fuel cell stack 10 to be described later becomes equal, and the temperature range of each device 34, 44 is changed. It is possible to achieve the same level, and the temperature variation of the fuel cell stack 10 can be suppressed.

  The second air preheater 34 is a high-temperature preheater that exchanges heat between the power generation air heated by the first air preheater 33 and combustion gas that is hotter than the combustion gas flowing through the first air preheater 33 ( An oxidant gas preheater).

  The second air preheater 34 of the present embodiment is housed inside the housing 2 together with the fuel cell stack 10, absorbs radiant heat generated during power generation of the fuel cell stack 10, and heats the air flowing through the inside. It consists of a radiant heat type heat exchanger. Note that power generation air lower than the temperature of the fuel cell stack 10 during power generation flows into the second air preheater 34.

  On the other hand, a fuel supply path 4 that is a fuel gas supply path is connected to the fuel gas inlet side of the fuel cell stack 10. In this fuel supply path 4, a desulfurizer 41 that removes sulfur components contained in the reformed raw material, a fuel blower 42 that pumps the reformed raw material, a fuel preheater 43, a fuel reformer, in order from the upstream side of the fuel gas flow. A container 44 is provided.

  The fuel preheater 43 is a preheater that heats the reformed raw material (referred to as fuel in FIG. 1) fed from the fuel blower 42 by exchanging heat with combustion gas generated by an off-gas combustor 61 described later. The fuel preheater 43 is also connected to the water supply path 5 and functions as a water vapor generator that evaporates water supplied from the water pump 52 via the pure water device 51 by heat exchange with the combustion gas. Plays. The fuel preheater 43 is a low-temperature preheater that exchanges heat between a fuel gas in which at least one of water and air and a reforming raw material are mixed with a combustion gas having a temperature lower than that of the fuel cell stack 10.

  An air supply path 3 a that is a supply path for reforming air is connected to a portion 4 a between the fuel blower 42 and the fuel preheater 43 in the fuel supply path 4. The air supply path 3a is provided with an air filter 31a for removing dust and dirt and an air blower 32a for pressure-feeding reforming air to the fuel cell stack 10 in order from the upstream side of the air flow.

  The fuel reformer 44 heats the fuel gas heated by the fuel preheater 43 by exchanging heat with the combustion gas, and generates a fuel gas containing hydrogen and carbon monoxide by steam reforming. It is.

  The fuel reformer 44 of this embodiment is housed inside the housing 2 together with the fuel cell stack 10 and the second air preheater 34, absorbs radiant heat generated during power generation of the fuel cell stack 10, and It consists of a radiant heat type heat exchanger that heats the fuel gas that circulates. Note that a mixed gas of reforming raw material and steam lower than the temperature of the fuel cell stack 10 during power generation (for example, 700 ° C. to 800 ° C.) flows into the fuel reformer 44.

  Here, although not shown, each of the air supply paths 3, 3 a and the fuel supply path 4 has an adjustment valve for adjusting the supply amount of the fuel gas supplied to the fuel cell stack 10 and the air supplied to the fuel cell stack 10. An adjustment valve or the like for adjusting the supply amount is provided.

  In this embodiment, in order to switch the reforming reaction of the fuel reformer 44 in the order of partial oxidation reforming reaction (POX reaction) → autothermal reforming reaction (ATR reaction) → steam reforming reaction (SR reaction), The material supplied to the preheater 43 is changed. When a partial oxidation reforming reaction (POX reaction) is performed in the fuel reformer 44, the reforming raw material and reforming air are supplied to the fuel preheater 43. When an autothermal reforming reaction (ATR reaction) is performed in the fuel reformer 44, the reforming raw material, reforming air, and water are supplied to the fuel preheater 43. When the steam reforming reaction (SR reaction) is performed in the fuel reformer 44, the reforming raw material and water are supplied to the fuel preheater 43.

  An air discharge path 6a through which exhaust air from the fuel cell stack 10 flows is connected to the air outlet side of the fuel cell stack 10, and a fuel discharge path through which discharged fuel flows to the fuel gas outlet side of the fuel cell stack 10 6b is connected. Each discharge path 6 a, 6 b is connected to an off-gas combustor 61.

  The off-gas combustor 61 mixes and burns the discharged fuel and the discharged air, and thus is used as a heat source for preheating the air and fuel gas supplied to the fuel cell stack 10 (for example, 900 ° C. to 1000 ° C. ) Combustion gas.

  The off gas combustor 61 is connected to a combustion gas path 6 for discharging high temperature combustion gas. The combustion gas path 6 is a device such as a fuel reformer 44, a second air preheater 34, a fuel preheater 43, and a first air preheater 33 in order from the upstream side in order to effectively use the heat of the combustion gas flowing inside. It is connected to the. Although not shown, a heat exchanger for heating hot water is provided on the downstream side of the first air preheater 33 in the combustion gas path 6, and the hot water is heated by the heat of the combustion gas. It is supposed to be.

  Then, the specific form inside the fuel cell apparatus 1 of this embodiment is demonstrated using FIG. 2 indicates the vertical direction when the fuel cell device 1 is mounted. The same applies to other drawings.

  As shown in FIG. 2, the fuel cell stack 10 is arranged so that the vertical direction coincides with the stacking direction of the power generation cells 100. The fuel cell stack 10 of the present embodiment has a stacking surface 10a extending in the stacking direction, an upper end surface 10b on the upper side in the stacking direction, and a lower end surface 10c on the lower side.

  In the fuel cell stack 10, an air introduction part 141 that introduces air into the interior is connected to an air outlet part 342 of a second air preheater 34, which will be described later, and an air exhaust part 142 that exhausts air from the inside is connected to the air exhaust path 6a. It is connected.

  Further, in the fuel cell stack 10, a fuel introduction part 151 for introducing fuel gas into the inside thereof is connected to a fuel outlet part 442 of a fuel reformer 44, which will be described later, and a fuel discharge part 152 for discharging fuel gas from the inside is discharged as fuel. It is connected to the path 6b.

  Subsequently, the second air preheater 34 and the fuel reformer 44 are arranged around the fuel cell stack 10. The second air preheater 34 and the fuel reformer 44 of this embodiment are arranged apart from the fuel cell stack 10 so as to be able to transfer heat (convection, conduction, radiation) to the fuel cell stack 10. . In the present embodiment, the second air preheater 34 and the fuel reformer 44 are disposed between one of the second air preheater 34 and the fuel reformer 44 and the fuel cell stack 10. The other heat exchanging means is arranged around the fuel cell stack 10 so as not to intervene.

  Here, the fuel cell stack 10 tends to have a higher temperature on the stacking surface 10a than the end surfaces 10b and 10c in the stacking direction during power generation. For this reason, the second air preheater 34 and the fuel reformer 44 of the present embodiment are disposed so as to face the stacked surface 10 a extending in the stacking direction in the fuel cell stack 10. Note that the second air preheater 34 and the fuel reformer 44 of the present embodiment have a stack facing surface facing the fuel cell stack 10 when viewed from the facing direction to the stacked surface 10a of the fuel cell stack 10. It arrange | positions so that it may overlap with the whole region of the lamination | stacking surface 10a.

  The second air preheater 34 is provided with an air inlet 341 for allowing the air heated by the first air preheater 33 to flow in on the lower side, and an air outlet for introducing air into the fuel cell stack 10 on the upper side. 342 is provided.

  The fuel reformer 44 is provided with a fuel inlet portion 441 for allowing the fuel gas heated by the fuel preheater 43 to flow into the lower side, and a fuel outlet for introducing the fuel gas into the fuel cell stack 10 on the upper side. A portion 442 is provided.

  Here, in the fuel cell stack 10, the heat radiation on the one end portion 10A side (see FIG. 3) and the other end portion 10C side in the stacking direction becomes remarkable compared to the middle step portion 10B in the stacking direction. The temperature on the part side and the other end side) tends to be lower than that of the middle stage part 10B. That is, the fuel cell stack 10 tends to have a temperature distribution that is the highest temperature in the middle stage portion 10B in the stacking direction. Such a temperature distribution of the fuel cell stack 10 is not preferable because it causes a decrease in power generation efficiency of the fuel cell stack 10 as a whole.

  Note that one end portion 10A of the fuel cell stack 10 is one end side region (for example, a region occupying 10% to 30%) in the stacking direction of the fuel cell stack 10, and the other end portion 10C is the stack of the fuel cell stack 10. It is a region on the other end side in the direction (for example, a region occupying 10% to 30%). The middle stage portion 10B of the fuel cell stack 10 is a region excluding the one end portion 10A and the other end portion 10C (for example, a region occupying 40% to 80%).

  Therefore, in the present embodiment, the reforming reaction (steam reforming reaction: SR reaction) involving the endothermic heat of the fuel reformer 44 at the middle stage facing part 44B facing the middle stage part 10B in the stacking direction of the fuel cell stack 10 is performed. The structure is the most promoted.

  The steam reforming in the reforming catalyst 443 is, for example, a reforming reaction accompanied by endotherm as shown by the reaction formula [F5], and is a high temperature condition capable of absorbing radiant heat generated during power generation of the fuel cell stack 10. By carrying out below, a reforming reaction with a higher conversion rate can be realized.

_{CH 4 + H 2 O → CO} + 3H 2 -206kJ / mol ... [F5]
Furthermore, in this embodiment, when the partial reforming reforming reaction (POX reaction) of the fuel gas is performed by the fuel reformer 44, the fuel reformer 44 is connected to the middle stage portion 10B in the stacking direction of the fuel cell stack 10. The reforming reaction accompanied by heat generation (partial oxidation reforming reaction: POX reaction) is most promoted in the middle stage confronting portion 44B facing the surface. That is, in the fuel reformer 44, the reforming reaction accompanied by heat generation (partial oxidation reforming reaction: POX reaction) is promoted in the middle stage facing part 44B as compared with the one end side facing part 44A and the other end side facing part 44C. It has a structure.

  Here, the fuel reformer 44 of the present embodiment includes one end side facing portion 44A facing the one end portion 10A side in the stacking direction of the fuel cell stack 10, and a middle stage facing portion 44B facing the middle step portion 10B side in the stacking direction. It has the other end side opposing part 44C which opposes to the other end part 10C side of the lamination direction.

  Hereinafter, the structure of the fuel reformer 44 of this embodiment will be described with reference to FIG.

  First, the inside of the fuel reformer 44 is filled with a reforming catalyst 443, and the reforming raw material and water vapor introduced from the fuel inlet 441 are directed from the one end side facing portion 44A toward the other end side facing portion 44C. Internal flow paths 44a to 44c for flowing are set.

  The reforming catalyst 443 is a catalyst that generates a fuel gas by reforming a mixed gas containing a reforming raw material in the internal channels 44a to 44c. For example, a catalyst on which a metal such as rhodium, ruthenium, or nickel is supported. It consists of

  The internal flow paths 44a to 44c of the present embodiment include an inlet-side flow path 44a extending from one end side facing part 44A to the middle stage facing part 44B, an intermediate flow path 44b corresponding to the middle stage facing part 44B, and the other end side from the middle stage facing part 44B. It is comprised by the exit side flow path 44c which reaches 44 C of confrontation parts. In the present embodiment, the inlet-side channel 44a constitutes the “first channel”, and the intermediate channel 44b and the outlet-side channel 44c constitute the “second channel”.

  In the present embodiment, the reforming catalyst 443 is not filled in the inlet-side channel 44a, but is filled only in the intermediate channel 44b and the outlet-side channel 44c. As a result, the amount of heat generated at the intermediate confronting portion 44B in the fuel reformer 44 becomes the highest when the partial oxidation reforming reaction (POX reaction) is performed, and the fuel reformer 44 when the steam reforming reaction (SR reaction) is performed. The endothermic amount at the middle stage antipodal region 44B at the highest is.

  Specifically, the fuel reformer 44 of this embodiment fills the reforming catalyst 443 only between the intermediate flow path 44b and the outlet flow path 44c between the inlet side flow path 44a and the intermediate flow path 44b. A restricting member 444 is provided for this purpose. The restricting member 444 is made of a metal mesh, punching metal, or the like so that the mixed gas from the fuel preheater 43 flows from the inlet-side flow path 44a to the intermediate flow path 44b.

  In the fuel reformer 44 of the present embodiment, the middle stage opposing part 44B and the other end side opposing part 44C constitute a high reforming region where a reforming reaction accompanied by heat generation (or endotherm) occurs, and one end side opposing part 44A constitutes an unmodified region where no reforming reaction accompanied by heat generation (or endotherm) occurs. Note that the one end side facing portion 44A functions as a preheating region for preheating the reforming raw material and steam introduced into the intermediate flow path 44b.

  Next, the operation of the fuel cell system according to the above configuration will be described. When the operation of the fuel cell system is started by a control command from a controller (not shown), the air blower 32, the fuel blower 42, the air blower 32a, etc. are operated.

  In the air supply path 3, the power generation air pressure-fed by the air blower 32 is heated to a desired temperature by the first air preheater 33, and further heated by the second air preheater 34. The fuel cell stack 10 is supplied.

  On the other hand, in the fuel supply path 4, the fuel gas (referred to as a reforming raw material in FIG. 2) fed by the fuel blower 42 and the reforming air fed by the air blower 32a are supplied to the portion 4a (FIG. 1)). The mixed fuel gas is heated to a desired temperature by the fuel preheater 43 and then flows to the fuel reformer 44. Along with this, a partial oxidation reforming reaction (POX reaction) of the fuel gas is performed in the fuel reformer 44. In this case, in the fuel reformer 44, as described above, the fuel gas pumped by the fuel blower 42 is reformed into a hydrogen-rich fuel gas by the reaction of the reaction formulas [F5] to [F8]. It is supplied to the battery stack 10.

  When fuel gas and air are supplied, the fuel cell stack 10 outputs electric energy by the electrochemical reaction shown in the above reaction formulas [F1] to [F4] using hydrogen and carbon monoxide as fuel.

  Exhaust fuel and exhaust air discharged from the fuel cell stack 10 are burned in the off-gas combustor 61. The high-temperature combustion gas generated in the off-gas combustor 61 flows in the order of the fuel reformer 44, the second air preheater 34, the fuel preheater 43, and the first air preheater 33 via the combustion gas path 6. After being used as a heat source in each device, it is discharged outside.

  Thereafter, the operation of the water pump 52 is started. For this reason, the water pumped from the water pump 52 is caused to flow to the fuel preheater 43. Therefore, the water pumped from the water pump 52, the fuel gas pumped by the fuel blower 42, and the reforming air pumped by the air blower 32a are brought to a desired temperature by the fuel preheater 43. After being heated, it flows to the fuel reformer 44. For this reason, in the fuel reformer 44, an autothermal reforming reaction (ATR reaction) is performed. In this case, in the fuel reformer 44, the fuel gas pumped by the fuel blower 42 is reformed into a hydrogen-rich fuel gas and supplied to the fuel cell stack 10. For this reason, the fuel cell stack 10 outputs electric energy by the electrochemical reaction shown in the above reaction formulas [F1] to [F4] using hydrogen and carbon monoxide as fuel.

  Next, the operation of the air blower 32a is stopped. For this reason, supply of the reforming air from the air blower 32a to the fuel preheater 43 is stopped. Accordingly, the fuel preheater 43 is supplied with water pumped from the water pump 52 and fuel gas pumped by the fuel blower 42. For this reason, in the fuel reformer 44, the steam reforming reaction (SR reaction) of the fuel gas is performed. In this case, in the fuel reformer 44, the fuel gas pumped by the fuel blower 42 is reformed into a hydrogen-rich fuel gas and supplied to the fuel cell stack 10. For this reason, the fuel cell stack 10 outputs electric energy by the electrochemical reaction shown in the above reaction formulas [F1] to [F4] using hydrogen and carbon monoxide as fuel.

  In the fuel cell device 1 of the present embodiment described above, the second air preheater 34 and the fuel reformer 44 are arranged so as to face the fuel cell stack 10. According to this, when the steam reforming reaction (SR reaction) of the fuel gas is performed, the radiant heat from the fuel cell stack 10 is converted into the second air preheat by the second air preheater 34 and the fuel reformer 44. Excess heat in the fuel cell stack 10 can be recovered by exchanging heat with the air and fuel gas flowing through the interior of the fuel cell 34 and the fuel reformer 44.

  Further, the fuel reformer 44 of the present embodiment is configured such that the reforming catalyst 443 is not filled in the inlet-side channel 44a, but is filled only in the intermediate channel 44b and the outlet-side channel 44c. For this reason, during the partial oxidation reforming reaction (POX reaction) of the fuel gas, a heat generation region, an endothermic region, and an equilibrium region are formed along the fuel gas flow direction from the middle stage facing part 44B to the other end side facing part 44C. The As a result, the fuel reformer 44 has a structure in which the reforming reaction accompanied by heat generation is most promoted at the middle-stage facing portion 44 </ b> B facing the middle-stage portion 10 </ b> B in the stacking direction of the fuel cell stack 10. That is, the fuel reformer 44 has a structure in which the reforming reaction accompanied by heat generation is most promoted at the time of start-up at the middle stage confronting part 44B.

  FIG. 4 shows a temperature distribution in which the horizontal axis represents the temperature of the fuel reformer 44 of the present embodiment and the vertical axis represents the fuel flow direction. According to this, the amount of heat generated by the reforming reaction of the fuel reformer 44 is highest at the middle stage confronting part 44B facing the middle stage part 10B in the fuel cell stack 10. For this reason, in the fuel reformer 44, the temperature of the middle-stage opposed portion 44B is higher than the temperature of the one-end opposed portion 44A, and the temperature of the middle-stage opposed portion 44B is higher than the temperature of the other-end opposed portion 44C. Become higher. That is, in the fuel reformer 44, a heat spot is formed in the middle stage 44B by the partial oxidation reforming reaction (POX reaction) of the fuel gas. Therefore, radiant heat is radiated from the middle stage 44 </ b> B of the fuel reformer 44 to the middle stage 10 </ b> B in the fuel cell stack 10. Accordingly, in the fuel cell stack 10, heat is transmitted from the middle stage portion 10B to the one end portion 10A side and the other end portion 10C side. Thereby, in the fuel cell stack 10, the temperature difference between the temperature on the one end portion 10A side and the temperature on the other end portion 10C side can be reduced, and the temperature distribution in the fuel cell stack 10 can be made uniform.

  According to the present embodiment, the middle stage confronting portion 44 </ b> B of the fuel reformer 44 can be cooled by radiant heat to the middle stage part 10 </ b> B in the fuel cell stack 10. Accordingly, it is possible to prevent the internal temperature of the fuel reformer 44 from falling below the heat-resistant temperature of the catalyst and the internal temperature of the fuel reformer 44 from being overheated. Can do.

  Furthermore, the fuel reformer 44 according to the present embodiment absorbs heat at the middle stage facing portion 44B facing the middle stage portion 10B in the stacking direction of the fuel cell stack 10 during the steam reforming reaction (SR reaction) of the fuel gas. The reforming reaction is most promoted.

  According to this, the amount of heat absorbed by the reforming reaction of the fuel reformer 44 is highest at the middle-stage facing portion 44B facing the middle-stage portion 10B that tends to be high temperature in the fuel cell stack 10. For this reason, the temperature at the middle stage portion 10B side of the fuel cell stack 10 can be lowered by the heat absorption in the middle stage facing portion 44B of the fuel reformer 44.

  In particular, in the present embodiment, the reforming catalyst 443 is filled only in the intermediate flow path 44b and the outlet-side flow path 44c among the internal flow paths 44a to 44c of the fuel reformer 44. According to this, the temperature of the reforming material flowing into the intermediate flow path 44b is raised by the heat on the one end portion 10A side of the fuel cell stack 10, and the reforming reaction in the intermediate flow path 44b is promoted. The amount of heat absorbed from the middle stage 10B of the fuel cell stack 10 in the container 44 can be increased. As a result, the temperature of the middle stage portion 10B of the fuel cell stack 10 is lowered by the heat absorption in the fuel reformer 44, and the temperature difference between the end portions 10A and 10C in the stacking direction of the fuel cell stack 10 and the middle stage portion 10B side. Can be reduced.

  Here, FIG. 5 is a characteristic diagram showing the temperature distribution of the fuel reformer (comparative example) in which the reforming catalyst 443 is provided in each of the internal flow paths 44 a to 44 c of the fuel reformer 44 and the fuel cell stack 10. . The solid line shown in FIG. 5 indicates the temperature distribution of the fuel cell stack 10 in the stacking direction (height direction) when the fuel reformer according to the comparative example is disposed so as to face the stacking surface 10a of the fuel cell stack 10. ing. 5 indicates a temperature distribution of the fuel reformer in the stacking direction when the fuel reformer according to the comparative example is not opposed to the stacking surface 10a of the fuel cell stack 10. 5 indicates the temperature distribution of the fuel cell stack 10 in the stacking direction when the fuel reformer according to the comparative example is not opposed to the stacking surface 10a of the fuel cell stack 10.

  As shown by the two-dot chain line in FIG. 5, in the fuel cell stack 10, the temperatures of both end portions 10A and 10C in the stacking direction are lower than those in the middle step portion 10B in the stacking direction. Note that, due to the influence of natural convection, in the fuel cell stack 10, the other end portion 10 </ b> C located on the upper side tends to be hotter than the one end portion 10 </ b> A located on the lower side.

  On the other hand, the fuel reformer according to the comparative example has a structure in which the reforming reaction with endotherm is most accelerated at the one end side facing portion 44A facing the one end portion 10A in the stacking direction of the fuel cell stack 10, and the fuel reforming is performed. The endothermic amount due to the reforming reaction of the vessel is highest at the one end side confronting portion 44A. Accordingly, in the fuel reformer according to the comparative example, the temperature of the one-end-side confronting portion 44A is the lowest, as shown by the one-dot chain line in FIG.

  When the fuel reformer having such a temperature distribution is opposed to the fuel cell stack 10, the temperature is the lowest on the one end portion 10A side of the fuel cell stack 10 due to heat absorption at the one end facing portion 44A of the fuel reformer. Thus, the temperature becomes highest at the middle stage 10B (see the solid line in FIG. 5). In the fuel cell stack 10, the temperature difference ΔT1 between the one end portion 10A side and the middle step portion 10B is greatly deviated.

  FIG. 6 is a characteristic diagram showing the temperature distribution of the fuel reformer 44 and the fuel cell stack 10 according to the present embodiment. Note that the solid line, the alternate long and short dash line, and the alternate long and two short dashes line shown in FIG. 6 are the same as the description of each line in FIG.

  As shown by the two-dot chain line in FIG. 6, in the fuel cell stack 10, the temperatures of both end portions 10A and 10C in the stacking direction are lower than those in the middle step portion 10B in the stacking direction. Note that, due to the influence of natural convection, in the fuel cell stack 10, the other end portion 10 </ b> C located on the upper side tends to be hotter than the one end portion 10 </ b> A located on the lower side.

  On the other hand, the fuel reformer 44 has a structure in which the reforming reaction with endotherm is most accelerated at the middle stage facing portion 44B facing the middle stage portion 10B in the stacking direction of the fuel cell stack 10, and the fuel reformer 44 is improved. The endothermic amount due to the quality reaction is highest at the middle antipodal region 44B. As a result, as shown by the one-dot chain line in FIG. 6, the fuel reformer 44 is lowered until the temperature of the middle-stage confronting portion 44B becomes substantially the same as that of the one-end-side confronting portion 44A.

  When the fuel reformer 44 having such a temperature distribution is opposed to the fuel cell stack 10, the temperature on the middle stage portion 10 </ b> B side of the fuel cell stack 10 greatly decreases due to heat absorption at the middle-stage facing portion 44 </ b> B of the fuel reformer 44. (Refer to the solid line in FIG. 6). In the fuel cell stack 10, the temperature difference ΔT2 between the both end portions 10A and 10C and the middle portion 10B is reduced.

  As described above, according to the fuel cell device 1 of the present embodiment, the temperature difference between the end portions 10A and 10C in the stacking direction of the fuel cell stack 10 and the middle portion 10B side is reduced, and the temperature in the fuel cell stack 10 is reduced. The distribution can be made uniform.

  In this embodiment, the example in which the reforming catalyst 443 is filled only in the intermediate flow path 44b and the outlet-side flow path 44c in the fuel reformer 44 has been described. However, the present invention is not limited to this. 443 may be filled only in the intermediate flow path 44b.

  This also makes it possible to reduce the temperature difference between the end portions 10A and 10C in the stacking direction of the fuel cell stack 10 and the middle stage portion 10B side, so that the temperature distribution in the fuel cell stack 10 can be made uniform. . The structure in which the reforming catalyst 443 in the fuel reformer 44 is filled only in the intermediate flow path 44b can also be applied to the following embodiments.

(Second Embodiment)
Next, a second embodiment will be described. In the present embodiment, description of the same or equivalent parts as in the first embodiment will be omitted or simplified.

  FIG. 7 is a configuration diagram showing the structure of the fuel reformer 44 according to the present embodiment. As shown in FIG. 7, the fuel reformer 44 of the present embodiment includes a reforming material and a fuel cell stack in an inlet-side channel 44a that is not filled with the reforming catalyst 443 among the internal channels 44a to 44c. A heat transfer promoting member 445 that promotes heat transfer with 10 is disposed.

  In the present embodiment, a spherical member such as a ceramic ball or an alumina ball having excellent thermal conductivity is employed as the heat transfer promoting member 445, and the spherical member is filled in the inlet-side flow path 44a.

  Other configurations and operations are the same as those in the first embodiment. That is, as in the first embodiment, the air blower 32a and the water pump 52 are operated to change the reforming reaction of the fuel reformer 44 from the partial oxidation reforming reaction (POX reaction) to the autothermal reforming reaction (ATR). Reaction) → Steam reforming reaction (SR reaction).

  According to the fuel cell device 1 of the present embodiment, the following effects are produced in addition to the effects described in the first embodiment. That is, according to the present embodiment, the temperature of the reforming raw material and water vapor flowing through the inlet-side flow path 44a of the fuel reformer 44 is easily raised by the heat on the one end 10A side of the fuel cell stack 10.

  As a result, the temperature of the reformed raw material flows into the intermediate flow path 44b of the fuel reformer 44, and the reforming reaction in the intermediate flow path 44b is promoted, whereby the fuel cell stack 10 in the fuel reformer 44 is accelerated. The amount of heat absorbed from the middle stage portion 10B can be increased.

  As a result, the temperature of the middle stage portion 10B of the fuel cell stack 10 is lowered by the heat absorption in the fuel reformer 44, and the temperature difference between the end portions 10A, 10C in the stacking direction of the fuel cell stack 10 and the middle stage portion 10B side. Can be further reduced. In this embodiment, an example in which a spherical member such as a ceramic ball or an alumina ball is used as the heat transfer promoting member 445 has been described. However, the present invention is not limited to this, and a plate-like fin or the like is used as the heat transfer promoting member 445. May be.

(Third embodiment)
Next, a third embodiment will be described. In the present embodiment, description of the same or equivalent parts as in the first and second embodiments will be omitted or simplified.

  FIG. 8 is a configuration diagram showing the structure of the fuel reformer 44 according to the present embodiment. As shown in FIG. 8, the fuel reformer 44 of the present embodiment includes a fuel cell stack in the intermediate flow path 44b and the outlet flow path 44c filled with the reforming catalyst 443 among the internal flow paths 44a to 44c. Fins 446 are arranged to promote radiant heat transfer from 10.

  The fins 446 are disposed so as to come into contact with the stack facing surface facing the fuel cell stack 10 in the fuel reformer 44 in the intermediate flow path 44b and the outlet-side flow path 44c.

  Other configurations and operations are the same as those in the first embodiment. That is, as in the first embodiment, the air blower 32a and the water pump 52 are operated to change the reforming reaction of the fuel reformer 44 from the partial oxidation reforming reaction (POX reaction) to the autothermal reforming reaction (ATR). Reaction) → Steam reforming reaction (SR reaction).

  According to the fuel cell device 1 of the present embodiment, the following effects are produced in addition to the effects described in the first embodiment. That is, according to the present embodiment, the radiant heat transfer from the middle stage portion 10B side of the fuel cell stack 10 is promoted, so that the reforming flowing through the intermediate flow path 44b and the outlet side flow path 44c of the fuel reformer 44. The temperature of the raw material rises.

  As a result, the reforming reaction in the intermediate flow path 44b and the outlet-side flow path 44c is promoted, so that the amount of heat absorbed from the middle stage portion 10B and the other end portion 10C of the fuel cell stack 10 in the fuel reformer 44 is increased. Can be made.

  As a result, the temperature of the middle stage portion 10B and the other end portion 10C of the fuel cell stack 10 is lowered by the heat absorption in the fuel reformer 44, and the one end portion 10A side and the middle step portion 10B side in the stacking direction of the fuel cell stack 10 It becomes possible to further reduce the temperature difference.

(Fourth embodiment)
Next, a fourth embodiment will be described. In the present embodiment, description of the same or equivalent parts as in the first to third embodiments will be omitted or simplified.

  FIG. 9 is a configuration diagram showing the structure of the fuel reformer 44 according to the present embodiment. As shown in FIG. 9, in the fuel reformer 44 of the present embodiment, the reforming catalyst 443 is filled in each of the internal flow paths 44a to 44c.

  In the present embodiment, the intermediate flow path 44b and the outlet-side flow path 44c among the internal flow paths 44a are so promoted that the reforming reaction with the most endotherm is promoted at the middle stage confronting portion 44B of the fuel reformer 44. In addition, more reforming catalyst 443 is filled than the inlet-side flow path 44a. That is, in this embodiment, the filling amount per unit volume of the reforming catalyst 443 in the intermediate flow path 44b and the outlet side flow path 44c is larger than the filling amount per unit volume of the reforming catalyst 443 in the inlet side flow path 44a. It is increasing.

  Other configurations and operations are the same as those in the first embodiment. That is, as in the first embodiment, the air blower 32a and the water pump 52 are operated to change the reforming reaction of the fuel reformer 44 from the partial oxidation reforming reaction (POX reaction) to the autothermal reforming reaction (ATR). Reaction) → Steam reforming reaction (SR reaction).

  According to the fuel cell device 1 of the present embodiment, the amount of heat absorbed by the reforming reaction of the fuel reformer 44 is the highest at the middle stage confronting portion 44B. The temperature on the middle stage 10B side can be lowered.

  Therefore, according to the fuel cell device 1 of the present embodiment, the temperature difference between the both end portions 10A and 10C in the stacking direction of the fuel cell stack 10 and the middle portion 10B side is reduced, and the temperature distribution in the fuel cell stack 10 is reduced. Uniformity can be achieved.

(Modification of the fourth embodiment)
In the present embodiment, an example has been described in which the intermediate flow path 44b and the outlet-side flow path 44c among the internal flow paths 44a of the fuel reformer 44 are filled with more reforming catalyst 443 than the inlet-side flow path 44a. However, it is not limited to this.

  For example, as shown in FIG. 10, among the internal flow paths 44a of the fuel reformer 44, the intermediate flow path 44b and the outlet-side flow path 44c are filled with the first active reforming catalyst 443a, and the inlet-side flow path is filled. 44a may be filled with a second reforming catalyst 443b having a lower activity than the first reforming catalyst 443a. Specifically, as the first reforming catalyst 443a filled in the intermediate flow path 44b and the outlet side flow path 44c, a reforming catalyst having a large amount of metal is adopted, and the second reforming catalyst filled in the inlet side flow path 44a. As the quality catalyst 443b, a reforming catalyst with a small amount of supported metal may be employed.

  Also by this, the amount of heat absorbed by the reforming reaction of the fuel reformer 44 becomes the highest in the middle stage confronting part 44B, so that the temperature on the middle stage 10B side of the fuel cell stack 10 is increased by the heat absorption in the fuel reformer 44. Can be reduced.

  Therefore, the fuel cell device 1 of the present modification also reduces the temperature difference between the end portions 10A, 10C in the stacking direction of the fuel cell stack 10 and the middle portion 10B side, as in the fourth embodiment. The temperature distribution in the battery stack 10 can be made uniform.

(Fifth embodiment)
Next, a fifth embodiment will be described. In the present embodiment, description of the same or equivalent parts as those in the first to fourth embodiments will be omitted or simplified.

  FIG. 11 is an overall configuration diagram of the fuel cell system of the present embodiment, and FIG. 12 is a configuration diagram showing the structure of the fuel reformer 44 of the present embodiment.

  As shown in FIG. 11, the fuel preheater 43 according to the present embodiment includes a raw material preheating unit 43 a that preheats the reformed raw material fed from the fuel blower 42, and water vapor generation that evaporates water supplied from the water pump 52. It consists of part 43b. The fuel preheater 43 is divided so that the reformed raw material passing through the raw material preheating unit 43a and water (steam) passing through the steam generation unit 43b are not mixed.

  The fuel preheater 43 is connected to a raw material introduction path 4a for introducing the reformed raw material preheated by the raw material preheater 43a into the fuel reformer 44, and is generated by the steam generator 43b. A steam introduction path 4 b for introducing the obtained steam into the fuel reformer 44 is connected. And the branch path 3a branched on the downstream side of the 1st air preheater 33 in the air supply path 3 is connected to the raw material introduction path 4a.

  Subsequently, as shown in FIG. 12, the reforming catalyst 443 is filled in each of the internal flow paths 44a to 44c in the fuel reformer 44 of the present embodiment. Then, in the fuel reformer 44, the raw material is introduced into the one end side facing portion 44A so that the reforming raw material and air (oxygen-containing gas) are introduced into the inlet-side flow channel 44a among the internal flow channels 44a to 44c. The path 4a is connected.

  Thereby, in the inlet side flow path 44a, fuel gas is produced | generated by the reforming reaction (partial oxidation reforming reaction: POX reaction) of a reforming raw material and air. The partial reforming reaction in the reforming catalyst 443 is a reforming reaction accompanied by heat generation, for example, as shown in the reaction formula [F6].

CH ₄ + 1 / 2O ₂ → CO + 2H ₂ +36 kJ / mol ... [F6]
In addition, in the fuel reformer 44, in addition to the passing gas (reforming raw material, air, etc.) that has passed through the inlet-side flow path 44a into the intermediate flow path 44b, water vapor is introduced into the middle-stage counter-part 44B. The water vapor introduction path 4b is connected.

  As a result, in the intermediate flow path 44b and the outlet-side flow path 44c, fuel gas is generated by a reforming reaction between the reforming raw material and steam (steam reforming reaction: SR reaction). Note that the steam reforming reaction in the reforming catalyst 443 is a reforming reaction with endotherm as described above (see the reaction formula [F5] in the first embodiment).

  Other configurations and operations are the same as those in the first embodiment. In the fuel reformer 44 of the present embodiment, the reforming raw material and air (oxygen-containing gas) are introduced so that partial oxidation reforming with heat generation is performed in the inlet-side channel 44a, and in the intermediate channel 44b. Steam is introduced so that steam reforming with endotherm is performed.

  According to this, the amount of heat absorbed by the reforming reaction of the fuel reformer 44 is the highest in the middle stage confronting portion 44B, and therefore the temperature on the middle stage 10B side of the fuel cell stack 10 due to the heat absorption in the fuel reformer 44. Can be reduced.

  Further, in the fuel reformer 44, the partial oxidation reforming accompanied by heat generation in the inlet-side flow path 44a is performed, so that the heat generation amount due to the reforming reaction of the fuel reformer 44 is highest at the one end side facing portion 44A. Become. For this reason, it is possible to raise the temperature of the one end portion 10A side of the fuel cell stack 10 by the heat generation in the one end facing portion 44A of the fuel reformer 44.

  As described above, according to the fuel cell device 1 of the present embodiment, the temperature of the middle stage portion 10B of the fuel cell stack 10 decreases due to the heat absorption generated in the intermediate flow path 44b of the fuel reformer 44, and one end portion of the fuel cell stack. The temperature on the 10A side is raised by heat generated in the inlet-side flow path 44a of the fuel reformer 44. For this reason, the temperature difference between the one end portion 10A side and the middle stage portion 10B side in the stacking direction of the fuel cell stack 10 can be reduced, and the temperature distribution of the fuel cell stack 10 can be made uniform.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, In the range described in the claim, it can change suitably. For example, various modifications are possible as follows.

  (1) In each of the above-described embodiments, the example in which the stacked body of power generation cells 100 having a flat plate structure is used as the fuel cell stack 10 is not limited to this. The stack 10 may be configured.

  (2) In each of the above-described embodiments, when the fuel reformer 44 is viewed from the facing direction to the stack surface 10a of the fuel cell stack 10, the stack facing surface facing the fuel cell stack 10 is the stack surface 10a. Although an example of arranging so as to overlap the entire area has been described, the present invention is not limited to this. When viewed from the facing direction of the fuel cell stack 10 with respect to the stack surface 10a, the fuel reformer 44 has a stack facing surface facing the fuel cell stack 10 overlapping at least the entire area of the stack surface 10a in the middle stage portion 10B. It suffices if they are arranged.

  The fuel reformer 44 is filled with a reforming catalyst 443 and the reforming raw material and water vapor introduced from the fuel inlet 441 are directed from the one end side facing portion 44A toward the other end side facing portion 44C. Internal flow paths 44a to 44c for flowing are formed.

  (3) In each of the above-described embodiments, as an internal structure of the fuel reformer 44, an example in which the reforming raw material flows through the fuel reformer 44 from the lower side toward the upper side has been described. However, it is not limited to this. For example, the fuel reformer 44 may have a structure in which the reforming raw material flows through the inside of the fuel reformer 44 from the upper side toward the lower side.

  (4) In each of the above-described embodiments, the example in which the air introduction part 141 and the fuel introduction part 151 of the fuel cell stack 10 are provided on the stacked surface 10a of the fuel cell stack 10 has been described, but the present invention is not limited to this. The air introduction part 141 and the fuel introduction part 151 may be provided on the lower end surface 10c and the upper end surface 10b of the fuel cell stack 10, for example.

  Further, the air discharge portion 142 and the fuel discharge portion 152 of the fuel cell stack 10 are not limited to the lower end surface 10c of the fuel cell stack 10, and may be provided on the upper end surface 10b of the fuel cell stack 10, for example.

  In each of the above-described embodiments, the example in which the air heated by the second air preheater 34 is introduced into the fuel cell stack 10 through the air introduction unit 141 has been described, but the present invention is not limited to this. For example, the fuel cell stack 10 may have a sealless structure, and air existing around the fuel cell stack 10 may be introduced into the fuel cell stack 10.

  Thus, the connection mode of the fuel cell stack 10, the fuel reformer 44, and the second air preheater 34 is not limited to the connection mode shown in the above-described embodiments, and may be changed as appropriate.

  (5) In each of the above embodiments, the first air preheater 33 and the second air preheater 34 are independent constituent devices, and the fuel preheater 43 and the fuel reformer 44 are independent constituent devices. However, the present invention is not limited to this. For example, the first air preheater 33 and the second air preheater 34 are integrated, and the fuel preheater 43 and the fuel reformer 44 are integrated, and these are arranged around the fuel cell stack 10. Good.

  (6) In each of the above-described embodiments, the example in which the second air preheater 34 and the fuel reformer 44 are arranged around the fuel cell stack 10 has been described, but the present invention is not limited to this. For example, only the fuel reformer 44 among the second air preheater 34 and the fuel reformer 44 may be disposed around the fuel cell stack 10.

  (7) In each of the above-described embodiments, the example in which the fuel cell stack 10, the second air preheater 34, and the fuel reformer 44 are accommodated in the housing 2 has been described. It may be omitted.

  (8) In each of the above-described embodiments, the example in which the fuel cell stack 10 is a solid oxide fuel cell that operates at a high temperature has been described. However, the present invention is not limited to this. For example, the fuel cell stack 10 operates at a high temperature. A molten carbonate fuel cell may be used.

  (9) In each of the above-described embodiments, the arrangement form in which the stacking direction of the fuel cell stack 10 is the same as the vertical direction has been described. However, the present invention is not limited to this, and for example, the stacking direction of the fuel cell stack 10 is the horizontal direction. It is good also as the arrangement | positioning form which becomes the same direction.

  (10) In the above-described embodiments, the reforming reaction of the fuel reformer 44 is performed in the order of partial oxidation reforming reaction (POX reaction) → autothermal reforming reaction (ATR reaction) → steam reforming reaction (SR reaction). Although an example of switching has been described, instead of this, one of a partial oxidation reforming reaction (POX reaction) and a steam reforming reaction (SR reaction) may be performed by the fuel reformer 44.

  (11) The above embodiments can be combined with each other as much as possible. Further, it goes without saying that elements constituting the embodiment are not necessarily essential except when clearly stated to be essential and clearly considered essential in principle.

  (12) In each of the above-described embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, the specific number is clearly specified when clearly indicated as essential. It is not limited to the specific number except when limited to.

  (13) In each of the above-described embodiments, when referring to the shape, positional relationship, etc. of the constituent elements, etc., unless specifically stated or limited in principle to a specific shape, positional relationship, etc. It is not limited to shape, positional relationship, and the like.

DESCRIPTION OF SYMBOLS 10 Fuel cell stack 10a Stacking surface 10B Middle part 100 Power generation cell 44 Fuel reformer 44B Middle stage confronting part 443 Reforming catalyst

Claims (14)

A fuel cell stack (10) configured by laminating a plurality of power generation cells (100) that output electrical energy by an electrochemical reaction of an oxidant gas and a fuel gas;
A fuel reformer (44) filled with a reforming catalyst (443) for reforming a hydrocarbon-based reforming raw material and generating the fuel gas introduced into the fuel cell stack;
The fuel reformer is disposed opposite to a stacking surface (10a) extending in the stacking direction of the power generation cells in the fuel cell stack so as to be able to transfer heat to the fuel cell stack, and the fuel cell The fuel cell device is characterized in that a reforming reaction accompanied by heat generation is most promoted at a middle-stage facing portion (44B) facing the middle-stage portion (10B) in the stacking direction of the stack. In the fuel reformer, the reforming material is confronted from one end side facing part (44A) facing the one end part (10A) side in the stacking direction of the fuel cell stack to the other end part (10C) side. Internal flow paths (44a to 44c) for flowing toward the other end side facing part (44C) are set,
A flow path from the one end side facing part to the middle stage facing part in the internal flow path is defined as a first flow path (44a), and a path from the middle stage facing part and the middle stage facing part to the other end side facing part is defined. When the second flow path (44b, 44c) is used,
2. The fuel cell device according to claim 1, wherein the reforming catalyst is filled only in the second flow path among the internal flow paths.   The heat transfer promoting member (444) for promoting heat transfer between the reforming raw material flowing through the first flow path and the fuel cell stack is disposed in the first flow path. 2. The fuel cell device according to 2. In the fuel reformer, the reforming material is confronted from one end side facing part (44A) facing the one end part (10A) side in the stacking direction of the fuel cell stack to the other end part (10C) side. Internal flow paths (44a to 44c) for flowing toward the other end side facing part (44C) are set,
A flow path from the one end side facing part to the middle stage facing part in the internal flow path is defined as a first flow path (44a), and a path from the middle stage facing part and the middle stage facing part to the other end side facing part is defined. When the second flow path (44b, 44c) is used,
The reforming catalyst is filled in each of the first flow path and the second flow path,
2. The fuel cell device according to claim 1, wherein the second flow path is filled with more reforming catalyst than the first flow path. In the fuel reformer, the reforming material is confronted from one end side facing part (44A) facing the one end part (10A) side in the stacking direction of the fuel cell stack to the other end part (10C) side. Internal flow paths (44a to 44c) for flowing toward the other end side facing part (44C) are set,
A flow path from the one end side facing part to the middle stage facing part in the internal flow path is defined as a first flow path (44a), and a path from the middle stage facing part and the middle stage facing part to the other end side facing part is defined. When the second flow path (44b, 44c) is used,
The reforming catalyst is filled in each of the first flow path and the second flow path,
2. The fuel cell device according to claim 1, wherein the second flow path is filled with the reforming catalyst (443 a) having higher activity than the first flow path.   6. The oxidizer according to claim 2, wherein an oxidant is introduced into at least the second flow path among the internal flow paths so that partial oxidation accompanied by heat generation is performed. Fuel cell device. 7. The fuel reformer according to any one of claims 1 to 6, wherein the reforming reaction with endotherm is most promoted at the intermediate stage portion after the reforming reaction with heat generation. The fuel cell device according to claim 1. A fuel cell stack (10) configured by laminating a plurality of power generation cells (100) that output electrical energy by an electrochemical reaction of an oxidant gas and a fuel gas;
A fuel reformer (44) filled with a reforming catalyst (443) for reforming a hydrocarbon-based reforming raw material and generating the fuel gas introduced into the fuel cell stack;
The fuel reformer is disposed opposite to a stacking surface (10a) extending in the stacking direction of the power generation cells in the fuel cell stack so as to be able to transfer heat to the fuel cell stack, and the fuel cell The fuel cell device is characterized in that the reforming reaction accompanied by endotherm is most promoted at the middle stage facing part (44B) facing the middle part (10B) in the stacking direction of the stack. In the fuel reformer, the reforming material is confronted from one end side facing part (44A) facing the one end part (10A) side in the stacking direction of the fuel cell stack to the other end part (10C) side. Internal flow paths (44a to 44c) for flowing toward the other end side facing part (44C) are set,
A flow path from the one end side facing part to the middle stage facing part in the internal flow path is defined as a first flow path (44a), and a path from the middle stage facing part and the middle stage facing part to the other end side facing part is defined. When the second flow path (44b, 44c) is used,
9. The fuel cell device according to claim 8, wherein the reforming catalyst is filled only in the second flow path among the internal flow paths.   The heat transfer promoting member (444) for promoting heat transfer between the reforming raw material flowing through the first flow path and the fuel cell stack is disposed in the first flow path. 9. The fuel cell device according to 9. In the fuel reformer, the reforming material is confronted from one end side facing part (44A) facing the one end part (10A) side in the stacking direction of the fuel cell stack to the other end part (10C) side. Internal flow paths (44a to 44c) for flowing toward the other end side facing part (44C) are set,
A flow path from the one end side facing part to the middle stage facing part in the internal flow path is defined as a first flow path (44a), and a path from the middle stage facing part and the middle stage facing part to the other end side facing part is defined. When the second flow path (44b, 44c) is used,
The reforming catalyst is filled in each of the first flow path and the second flow path,
The fuel cell device according to claim 8, wherein the second flow path is filled with more reforming catalyst than the first flow path. In the fuel reformer, the reforming material is confronted from one end side facing part (44A) facing the one end part (10A) side in the stacking direction of the fuel cell stack to the other end part (10C) side. Internal flow paths (44a to 44c) for flowing toward the other end side facing part (44C) are set,
A flow path from the one end side facing part to the middle stage facing part in the internal flow path is defined as a first flow path (44a), and a path from the middle stage facing part and the middle stage facing part to the other end side facing part is defined. When the second flow path (44b, 44c) is used,
The reforming catalyst is filled in each of the first flow path and the second flow path,
The fuel cell device according to claim 8, wherein the second flow path is filled with the reforming catalyst (443a) having a higher activity than the first flow path.   13. The steam according to claim 9, wherein steam is introduced into at least the second channel among the internal channels so that steam reforming with endotherm is performed. Fuel cell device. In the fuel reformer, the reforming material is confronted from one end side facing part (44A) facing the one end part (10A) side in the stacking direction of the fuel cell stack to the other end part (10C) side. Internal flow paths (44a to 44c) for flowing toward the other end side facing part (44C) are set,
A flow path from the one end side facing part to the middle stage facing part in the internal flow path is defined as a first flow path (44a), and a path from the middle stage facing part and the middle stage facing part to the other end side facing part is defined. When the second flow path (44b, 44c) is used,
The reforming catalyst is filled in each of the first flow path and the second flow path,
The reforming raw material and the oxygen-containing gas are introduced into the first flow path so that partial oxidation reforming with heat generation is performed,
9. The fuel cell according to claim 8, wherein steam is introduced into the second channel in addition to the passing gas that has passed through the first channel so that steam reforming with endotherm is performed. apparatus.

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