JP2014075246A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system having high energy efficiency.SOLUTION: The fuel cell system comprises: a fuel generation member 1 for generating a fuel gas by chemical reaction; a fuel cell unit 2 for generating power by using the fuel gas supplied from the fuel generation member; a gas passage for circulating gas between the fuel generation member and the fuel cell unit; a circulator 8 disposed in the gas passage and forcibly circulating gas between the fuel generation member and the fuel cell unit; and a circulator control unit for controlling the amount of gas circulated by the circulator so that the circulated amount of gas becomes equal to or less than a minimum value in the range of amounts of gas circulated by the circulator at which value the amount of fuel gas generated by the fuel generation unit becomes maximum.

Description

  The present invention relates to a fuel cell system including a fuel generating member.

  A fuel cell typically includes a solid polymer electrolyte membrane using a solid polymer ion exchange membrane, a solid oxide electrolyte membrane using yttria-stabilized zirconia (YSZ), a fuel electrode (anode) and an oxidizer electrode. The one sandwiched from both sides by the (cathode) has a single cell configuration. A fuel gas channel for supplying a fuel gas (for example, hydrogen) to the fuel electrode and an oxidant gas channel for supplying an oxidant gas (for example, oxygen or air) to the oxidant electrode are provided. Electric power is generated by supplying the fuel gas and the oxidant gas to the fuel electrode and the oxidant electrode, respectively.

  Fuel cells are not only energy-saving because of the high efficiency of the power energy that can be extracted in principle, but they are also a power generation system that excels in the environment, and are expected as a trump card for solving global energy and environmental problems.

Japanese National Patent Publication No. 11-501448 International Publication No. 2012/043271 JP 2003-217627 A

  Patent Document 1 and Patent Document 2 disclose a secondary battery type fuel cell system that combines a solid oxide fuel cell and a hydrogen generating member that generates hydrogen by an oxidation reaction and can be regenerated by a reduction reaction. Yes. In the secondary battery type fuel cell system, the hydrogen generating member generates hydrogen during the power generation operation of the system, and the hydrogen generating member is regenerated during the charging operation of the system.

  As a typical form of the hydrogen generating member, there can be mentioned a form in which a large number of pellets in which fine particles having metal as a base material, which generates hydrogen by an oxidation reaction and is regenerated by a reduction reaction, are compacted are arranged in a space. .

  In order to increase the generation efficiency of the fuel gas, it is desirable that the pellet not only stay on the surface but react with the gas to the inside to oxidize or reduce, but because of the structure in which the fine particles are consolidated, the gas is inside the pellet. Hard to penetrate. In addition, the oxidation reaction that occurs during the hydrogen generation of the hydrogen generating member is accompanied by an increase in the volume of the fine particles. First, the fine particles expand due to the oxidation reaction with the oxidizing gas on the pellet surface, and the hydrogen generating member is oxidized. As it progresses, an oxidation reaction with the oxidizing gas occurs inside the pellet, but the expansion of the fine particles prevents the penetration of the oxidizing gas into the hydrogen generating member, making it more difficult for the gas to penetrate into the pellet. Become.

  For this reason, it is desirable to take measures to promote gas permeation into the pellet, but care must be taken not to consume wasted energy when taking such measures.

  Note that the fuel supply amount control device disclosed in Patent Document 3 only compensates the amount of fuel supplied to the fuel cell based on the load power and the output power of the fuel cell. The fuel supply amount is not controlled in consideration of this condition.

  In view of the above situation, an object of the present invention is to provide a fuel cell system with high energy efficiency.

  In order to achieve the above object, a fuel cell system according to a first aspect of the present invention generates power using a fuel generating member that generates a fuel gas by a chemical reaction, and the fuel gas supplied from the fuel generating member. A fuel cell section to be performed, a gas flow path for circulating gas between the fuel generation member and the fuel cell section, and provided on the gas flow path, between the fuel generation member and the fuel cell section A circulator that forcibly circulates gas, and a fuel gas generation amount at the fuel generating member at the time of power generation by the fuel cell unit is less than a minimum value of a gas circulation amount range of the circulator that maximizes the amount of fuel gas generated. And a circulator control unit that controls a gas circulation amount of the circulator (first configuration).

  In order to achieve the above object, a fuel cell system according to a second aspect of the present invention includes a fuel generating member that generates a fuel gas by a chemical reaction and can be regenerated by a reverse reaction of the chemical reaction, and a fuel generating member. A power generation / electrolysis unit having a power generation function for generating power using the supplied fuel gas and an electrolysis function for electrolyzing the product of the reverse reaction supplied from the fuel generation member during regeneration of the fuel generation member A gas flow path for circulating gas between the fuel generating member and the power generation / electrolysis unit, and a product of the reverse reaction generated in the fuel generating member during regeneration of the fuel generating member. A configuration (second configuration) is provided that includes a circulator control unit that controls the gas circulation amount of the circulator so as to be equal to or less than the minimum value of the gas circulation amount range of the circulator where the generation amount is maximum. In addition, the power generation / electrolysis unit may, for example, generate power using the fuel gas supplied from the fuel generation member, and the reverse supplied from the fuel generation member during regeneration of the fuel generation member. The fuel cell may be configured to switch between an electrolysis operation for electrolyzing the product of the reaction, and, for example, a fuel cell that generates power using the fuel gas supplied from the fuel generating member; A configuration may be provided separately with an electrolyzer that electrolyzes the product of the reverse reaction supplied from the fuel generating member during regeneration of the fuel generating member.

  Further, in the fuel cell system of the second configuration, the circulator control unit is configured to perform gas circulation of the circulator that maximizes the amount of fuel gas generated in the fuel generation member during power generation by the power generation / electrolysis unit. It is preferable to adopt a configuration (third configuration) for controlling the gas circulation amount of the circulator so as to be equal to or less than the minimum value of the amount range.

  Further, in the fuel cell system of the first configuration, the fuel generating member is formed of fine particles, and the fine particles have a metal base material (fourth configuration) that generates fuel gas by the chemical reaction. Also good.

  Further, in the fuel cell system of the second or third configuration, the fuel generating member is formed of fine particles, and the fine particles generate a fuel gas by the chemical reaction and use a metal that can be regenerated by the reverse reaction. It is good also as composition (5th composition) used as material.

  In the fuel cell system having any one of the first to fifth configurations, the fuel generation member may be configured to be divided into a plurality of containers (sixth configuration).

  According to the fuel cell system of the first aspect of the present invention, the circulator control unit is configured to minimize the gas circulation amount range of the circulator in which the amount of fuel gas generated in the fuel generation member is maximized when the fuel cell unit generates power. Since the gas circulation rate of the circulator is controlled so as to be less than the value, an increase in the gas circulation rate that does not lead to an increase in the amount of fuel gas generation can be prevented. Therefore, it is possible to eliminate useless energy for driving the circulator during power generation of the fuel cell unit, and to increase energy efficiency.

  According to the fuel cell system according to the second aspect of the present invention, the circulator control unit causes the circulator gas to maximize the amount of the product of the reverse reaction generated in the fuel generating member during regeneration of the fuel generating member. Since the gas circulation rate of the circulator is controlled so as to be equal to or less than the minimum value of the circulation rate range, it is possible to prevent an increase in the gas circulation rate that does not lead to an increase in the generation amount of the product of the reverse reaction. Therefore, when the fuel generating member is regenerated, unnecessary energy is not consumed for driving the circulator, and energy efficiency can be increased.

It is a mimetic diagram showing a schematic structure of a fuel cell system concerning one embodiment of the present invention. It is a schematic diagram which shows the gas flow of the pellet surface vicinity. It is a figure which shows the relationship between the amount of gas circulation, and the amount of hydrogen generation. It is a figure which shows the relationship between the amount of gas circulation, and the amount of hydrogen generation. It is a schematic diagram which shows a fuel generation member. It is a figure which shows the relationship between the amount of gas circulation, and the amount of hydrogen generation. It is a figure which shows the relationship between the amount of gas circulation, and the amount of hydrogen generation. It is a schematic diagram which shows a fuel generation member. It is a figure which shows the relationship between the amount of gas circulation, and the amount of hydrogen generation. It is a schematic diagram which shows a fuel generation member. It is a figure which shows the relationship between the amount of gas circulation, and the amount of hydrogen generation. It is a schematic diagram which shows a fuel generation member. It is a schematic diagram which shows a fuel generation member. It is the elements on larger scale of a fuel generation member.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not restricted to embodiment mentioned later.

  The fuel cell system according to this embodiment includes a fuel generating member 1, a fuel cell unit 2, a heater 3 for heating the fuel generating member 1, a heater 4 for heating the fuel cell unit 2, the fuel generating member 1 and the heater. 3, a container 6 for storing the fuel cell unit 2 and the heater 4, a pipe 7 for circulating gas between the fuel generating member 1 and the fuel cell unit 2, the fuel generating member 1 and the fuel From a pump 8 that forcibly circulates gas between the battery parts 2, a heat insulating container 9, a pipe 10 for supplying air to the air electrode 2 </ b> C of the fuel cell part 2, and an air electrode 2 </ b> C of the fuel cell part 2 A pipe 11 for discharging air and a system controller 12 for controlling the entire system are provided. The heat insulating container 9 accommodates the containers 5 and 6 and a part of each of the pipes 7, 10, and 11. In addition, in order to prevent the figure from becoming complicated, illustration of a power line for transmitting power and a control line for transmitting control signals is omitted. Moreover, you may provide a temperature sensor etc. around the fuel generation member 1 and the fuel cell part 2 as needed. Further, instead of the pump 8, other circulators such as a compressor, a fan, and a blower may be used.

As the fuel generating member 1, for example, a metal or a metal oxide is added to the surface of a metal as a base material, and a fuel gas (for example, hydrogen) is generated by an oxidation reaction with an oxidizing gas (for example, water vapor). Further, those that can be regenerated by a reduction reaction with a reducing gas (for example, hydrogen) can be used. Examples of the base metal include Ni, Fe, Pd, V, Mg, and alloys based on these, and Fe is particularly preferable because it is inexpensive and easy to process. Examples of the added metal include Al, Rd, Pd, Cr, Ni, Cu, Co, V, and Mo. Examples of the added metal oxide include SiO ₂ and TiO ₂ . However, the metal used as a base material and the added metal are not the same material. In this embodiment, a fuel generating member mainly composed of Fe is used as the fuel generating member 1.

The fuel generating member mainly composed of Fe can generate hydrogen as a fuel gas (reducing gas) by consuming water vapor as an oxidizing gas, for example, by an oxidation reaction represented by the following formula (1). .
4H ₂ O + 3Fe → 4H ₂ + Fe ₃ O ₄ (1)

When the oxidation reaction of iron shown in the above formula (1) proceeds, the change from iron to iron oxide proceeds and the remaining amount of iron decreases, but the reverse reaction of the above formula (1), that is, the following (2 The fuel generating member 1 can be regenerated by the reductive reaction shown in the formula. The iron oxidation reaction shown in the above formula (1) and the reduction reaction in the following formula (2) can also be performed at a low temperature of less than 600 ° C.
4H ₂ + Fe ₃ O ₄ → 3Fe + 4H ₂ O (2)

  As shown in FIG. 1, the fuel cell unit 2 has an MEA structure (membrane / electrode assembly) in which a fuel electrode 2B and an air electrode 2C as an oxidant electrode are bonded to both surfaces of an electrolyte membrane 2A. Although FIG. 1 illustrates a structure in which only one MEA is provided, a plurality of MEAs may be provided, or a plurality of MEAs may be stacked.

  As a material of the electrolyte membrane 2A, for example, a solid oxide electrolyte using yttria-stabilized zirconia (YSZ) can be used. Solid polymer electrolytes such as, but not limited to, those that pass hydrogen ions, those that pass oxygen ions, and those that pass hydroxide ions can be used as fuel cell electrolytes. Any material satisfying the characteristics may be used. In the present embodiment, an electrolyte that passes oxygen ions or hydroxide ions, for example, a solid oxide electrolyte using yttria-stabilized zirconia (YSZ) is used as the electrolyte membrane 2A.

  In the case of a solid oxide electrolyte, the electrolyte membrane 2A can be formed using an electrochemical vapor deposition method (CVD-EVD method; Chemical Vapor Deposition-Electrochemical Vapor Deposition) or the like. If there is, it can be formed using a coating method or the like.

  Each of the fuel electrode 2B and the air electrode 2C can be configured by, for example, a catalyst layer in contact with the electrolyte membrane 2A and a diffusion electrode laminated on the catalyst layer. As the catalyst layer, for example, platinum black or a platinum alloy supported on carbon black can be used. Further, as a material for the diffusion electrode of the fuel electrode 2B, for example, carbon paper, Ni—Fe cermet, Ni—YSZ cermet, or the like can be used. Moreover, as a material of the diffusion electrode of the air electrode 2C, for example, carbon paper, La—Mn—O-based compound, La—Co—Ce-based compound, or the like can be used. Each of the fuel electrode 2B and the air electrode 2C can be formed by using, for example, vapor deposition.

  In the following description, a case where hydrogen is used as the fuel gas will be described.

During power generation of the fuel cell system according to the present embodiment, the fuel cell unit 2 is electrically connected to an external load (not shown) under the control of the system controller 12. In the fuel cell unit 2, the following reaction (3) occurs in the fuel electrode 2B during power generation of the fuel cell system according to the present embodiment.
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (3)

The electrons generated by the reaction of the above formula (3) pass through an external load (not shown) and reach the air electrode 2C, and the reaction of the following formula (4) occurs in the air electrode 2C.
1 / 2O ₂ + 2e ⁻ → O ²⁻ (4)

And the oxygen ion produced | generated by reaction of said (4) Formula reaches | attains the fuel electrode 2B through electrolyte membrane 2A. By repeating the above series of reactions, the fuel cell unit 2 performs a power generation operation. Further, as can be seen from the above equation (3), during the power generation operation of the fuel cell system according to the present embodiment, H ₂ is consumed and H ₂ O is generated on the fuel electrode 2B side.

From the above equations (3) and (4), the reaction in the fuel cell unit 2 during the power generation operation of the fuel cell system according to the present embodiment is as shown in the following equation (5).
H ₂ + 1 / 2O ₂ → H ₂ O (5)

On the other hand, the fuel generating member 1 consumes H ₂ O generated on the fuel electrode 2B side of the fuel cell unit 2 during power generation of the fuel cell system according to the present embodiment by the oxidation reaction shown in the above formula (1). To produce H ₂ .

  When the oxidation reaction of iron shown in the above formula (1) proceeds, the change from iron to iron oxide proceeds and the remaining amount of iron decreases, but the fuel generating member is reduced by the reduction reaction shown in the above formula (2). 1 can be regenerated, and the fuel cell system according to this embodiment can be charged.

When the fuel generating member 1 is regenerated, that is, when the fuel cell system according to this embodiment is charged, the fuel cell unit 2 is connected to an external power source (not shown) under the control of the system controller 12. In the fuel cell unit 2, when the fuel cell system according to the present embodiment is charged, an electrolysis reaction shown in the following formula (6), which is the reverse reaction of the formula (5), occurs, and H ₂ is generated on the fuel electrode 2B side. O is consumed and H ₂ is generated. In the fuel generating member 1, the reduction reaction shown in the above formula (2) occurs, and the H ₂ generated on the fuel electrode 2B side of the fuel cell unit ₂ is consumed and H ₂ O is consumed. Is generated.
H ₂ O → H ₂ + 1 / 2O ₂ (6)

  The system controller 12 controls the entire system, for example, switches between the power generation operation and the electrolysis operation of the fuel cell unit 2 and controls the gas circulation amount of the pump 8.

  In the fuel generating member 1, it is desirable to increase the surface area per unit volume in order to increase the reactivity. As a measure for increasing the surface area per unit volume of the fuel generating member 1, for example, the main body of the fuel generating member 1 may be made into fine particles, and the fine particles may be molded. Examples of the fine particles include a method of crushing particles by crushing using a ball mill or the like. Further, the surface area of the fine particles may be further increased by generating cracks in the fine particles by a mechanical method or the like, and the surface area of the fine particles is further increased by roughening the surface of the fine particles by acid treatment, alkali treatment, blasting, etc. It may be increased.

  Here, the form of the fuel generating member 1 will be considered in terms of the amount of hydrogen generated when Fe fine particles are pressed into pellets and a plurality of pellets are arranged in the container 5. In FIG. 2 to be described later, the gas flow is schematically shown by arrows. The thickness of the arrow line indicates the gas pressure, and the thicker the arrow line, the higher the gas pressure.

First, as shown in FIG. 2A, when the gas circulation amount of the pump 8 is small, the hydrogen generation amount in the fuel generating member 1 increases as the gas circulation amount increases. This is because as the gas circulation amount of the pump 8 increases, the area of the pellet 13 that reacts with the oxidizing gas (H ₂ O) increases and the amount of hydrogen generated in the fuel generating member 1 increases.

When the gas circulation amount of the pump 8 is further increased as shown in FIG. 2 (b), the penetration of the oxidizing gas (H ₂ O) into the pellet 13 proceeds with the increase of the gas circulation amount, and the fuel generating member The amount of hydrogen generated at 1 increases.

When the gas circulation amount of the pump 8 is further increased as shown in FIG. 2C, the hydrogen generation amount in the fuel generating member 1 increases as the gas circulation amount increases, but the oxidizing gas ( Since the penetration of H ₂ O) becomes difficult, the rate of increase in the amount of hydrogen generation slows down.

When the gas circulation amount of the pump 8 is further increased as shown in FIG. 2D, the hydrogen generation amount in the fuel generating member 1 decreases conversely when the gas circulation amount increases. This is because the pressure of the gas flow circulating between the fuel generating member 1 and the fuel cell unit 2 increases as the gas circulation amount of the pump 8 increases, and the pressure around the gas flow is higher than the pressure inside the pellet 13. This is because the flow of gas 14 from the inside of the pellet 13 toward the periphery of the gas flow is reduced and the penetration of the oxidizing gas (H ₂ O) into the inside of the pellet 13 is hindered.

  Thus, the relationship between the gas circulation amount of the pump 8 and the hydrogen generation amount in the fuel generating member 1 is as shown in FIG. 3 and FIG. Therefore, the system controller 12 sets the gas in the pump 8 so that the fuel gas generation amount in the fuel generating member 1 is the minimum value Vmin or less in the gas circulation amount range of the pump 8 when the fuel cell unit 2 generates power. Control the amount of circulation. That is, the system controller 12 sets the gas circulation amount of the pump 8 to an arbitrary value between 0 and Vmin during power generation of the fuel cell unit 2. Such control can prevent an increase in the amount of gas circulation that does not lead to an increase in the amount of hydrogen generation. Therefore, it is possible to eliminate useless energy for driving the pump 8 during power generation of the fuel cell unit 2, and to increase energy efficiency.

  Next, the relationship between each element of the fuel generating member 1 composed of a plurality of pellets and the hydrogen generation amount will be described. In addition, illustration of the heater accommodated in the container 5 is abbreviate | omitted in the figure used by the following description.

(I) Relationship between pellet size and hydrogen generation amount As shown in FIG. 5 (a), when the pellet 13 is large, the gap between the pellets 13 is large, so the gas circulation amount of the pump 8 is small and the fuel generation member 1 Even if the pressure of the gas flow circulating between the fuel cell parts 2 is low, the gas spreads to a deep part of the container 5 (a part away from the gas flow circulating between the fuel generating member 1 and the fuel cell part 2). However, since the pellet 13 is large, in order to infiltrate the gas into the pellet 13, it is necessary to increase the gas circulation amount of the pump 8 and increase the pressure of the gas flow circulating between the fuel generating member 1 and the fuel cell unit 2. There is.

  On the other hand, when the pellet 13 is small as shown in FIG. 5B, the gap between the pellets 13 is small, so that the gas circulation amount of the pump 8 is small and the gas flow circulating between the fuel generating member 1 and the fuel cell unit 2 is small. If the pressure is low, the gas will not reach the deep part of the container 5. However, since the pellet 13 is small, even if the gas circulation amount of the pump 8 is small and the pressure of the gas flow circulating between the fuel generating member 1 and the fuel cell unit 2 is low, the shallow portion of the container 5 (the fuel generating member 1 and the fuel) In the pellet 13 located in the portion near the gas flow circulating between the battery units 2, the gas penetrates into the pellet 13. When the gas circulation amount of the pump 8 is increased to increase the pressure of the gas flow circulating between the fuel generating member 1 and the fuel cell unit 2, the gas reaches the deep part of the container 5, but the pellet 13 is large. The gas does not reach the deep part of the container 5 as much as the case.

  Therefore, the hydrogen generation amount characteristic graph 15 when the pellet 13 is large as shown in FIG. 5A and the hydrogen generation amount characteristic graph 16 when the pellet 13 is small as shown in FIG. As shown. Vmin (a) in FIG. 6 is a pump 8 that maximizes the amount of fuel gas generated in the fuel generating member 1 when the fuel cell unit 2 generates power when the pellet 13 is large as shown in FIG. This is the minimum value of the gas circulation rate range. Vmin (b) in FIG. 6 is a pump 8 that maximizes the amount of fuel gas generated in the fuel generating member 1 when the fuel cell unit 2 generates power when the pellet 13 is small as shown in FIG. 5B. This is the minimum value of the gas circulation rate range. Although not shown in FIG. 5, a support member such as a metal mesh may be provided inside the container 5 in order to prevent the pellet 13 from falling in the direction of gravity.

(Ii) Relationship between the depth of the container and the amount of hydrogen generated When the pellet 13 is large as shown in FIG. 5 (a), the gas reaches the deep part of the container 5 as described above. As a result, the number of pellets that react with the gas increases, and the amount of hydrogen generation increases.

  On the other hand, as shown in FIG. 5B, when the pellet 13 is small, the gas does not spread to the deep part of the container 5 as the pellet 13 is large. For this reason, even if the container 5 is deepened, the amount of hydrogen generation does not increase so much.

  Therefore, the increase in the amount of hydrogen generated when the container 5 is deepened is more remarkable when the pellet 13 is larger than when the pellet 13 is small (see FIG. 7). In FIG. 7, the same reference numerals are assigned to the same graphs as in FIG. A graph 17 in FIG. 7 is a hydrogen generation amount characteristic graph when the pellet 13 is large as shown in FIG. 5A, and the hydrogen generation when the container 5 is deeper than the graph 15 by a predetermined amount. It is a quantity characteristic graph. Moreover, the graph 18 in FIG. 7 is a hydrogen generation amount characteristic graph in the case where the pellet 13 is small as shown in FIG. 5B, and the case where the container 5 is made a predetermined amount deeper than in the graph 16. It is a hydrogen generation amount characteristic graph.

(Iii) Relationship between the flow path length of the container and the hydrogen generation amount When the flow path of the container 5 (path along which the gas flow circulating between the fuel generating member 1 and the fuel cell unit 2 follows) is long as shown in FIG. The amount of hydrogen generated differs between the vicinity of the circulation gas inlet of the container 5 and the vicinity of the circulation gas outlet. The pressure of the gas flow (circulation gas flow) that circulates between the fuel generating member 1 and the fuel cell unit 2 is greater in the vicinity of the circulation gas outlet than in the vicinity of the circulation gas inlet due to pressure loss in the container 5. Lower. In the vicinity of the circulating gas outlet of the vessel 5, the pressure of the circulating gas flow is originally low, so even if the circulating gas flow rate is increased, the pressure of the circulating gas flow does not increase easily, and as a result, the amount of hydrogen generation does not increase easily (Fig. 9).

  A graph 19 in FIG. 9 is a hydrogen generation amount characteristic graph in the vicinity of the circulating gas inlet of the container 5 when the flow path of the container 5 is long as shown in FIG. A graph 20 in FIG. 9 is a hydrogen generation amount characteristic graph in the vicinity of the circulation gas outlet of the container 5 when the flow path of the container 5 is long as shown in FIG.

  As shown in FIG. 10, when the pellets 13 constituting the fuel generating member 1 are separately accommodated in a plurality of containers and the flow paths of the plurality of containers are long, as in the case shown in FIG. The amount of hydrogen generation differs between the circulating gas inlet 22 and the circulating gas outlet 23 of the entire plurality of containers.

  When the hydrogen generation amount in the fuel generating member 1 is locally different as described above, the system controller 12 calculates, for example, the average of the hydrogen generation amount at the circulation gas inlet and the hydrogen generation amount at the circulation gas outlet. Thus, the hydrogen generation amount characteristic of the entire fuel generation member 1 is obtained, and the minimum value of the gas circulation amount range of the pump 8 at which the generation amount of the fuel gas in the entire fuel generation member 1 is maximized when the fuel cell unit 2 generates power. What is necessary is just to control the gas circulation amount of the pump 8 so that it may become Vmin or less. A graph 21 in FIG. 9 is a hydrogen generation amount characteristic graph of the entire fuel generating member 1 when the flow path of the container 5 is long as shown in FIG.

(Iv) Relationship between the ratio of the fuel generating member not undergoing the oxidation reaction and the hydrogen generation amount The oxidation reaction of the pellet 13 occurs from the surface of the pellet 13 and the Fe fine particles expand due to the oxidation reaction. It becomes difficult for gas to penetrate 13 inside. Therefore, as the proportion of the fuel generating member 1 that has not undergone the oxidation reaction (remaining amount of iron) decreases, the amount of hydrogen generation is less likely to increase even if the circulation gas flow rate is increased (see FIG. 11).

  A graph 24 in FIG. 11 is a hydrogen generation amount characteristic graph in the case where the ratio (remaining amount of iron) in which the fuel generating member 1 is not oxidized is 100%, and Vmin (100%) in FIG. In the case where the ratio (remaining amount of iron) in which the fuel generating member 1 is not oxidized is 100%, the amount of fuel gas generated in the fuel generating member 1 is maximized when the fuel cell unit 2 generates power. This is the minimum value of the gas circulation amount range of the pump 8. A graph 25 in FIG. 11 is a hydrogen generation amount characteristic graph in a case where the ratio (remaining amount of iron) in which the fuel generating member 1 does not undergo oxidation reaction is 50%, and Vmin (50 in FIG. 11). %) Is the maximum amount of fuel gas generated in the fuel generating member 1 when the fuel cell unit 2 generates power when the ratio (remaining amount of iron) of the fuel generating member 1 that has not undergone the oxidation reaction is 50%. This is the minimum value of the gas circulation amount range of the pump 8.

  Considering the relationship between the proportion of the fuel generating member that has not undergone the oxidation reaction and the amount of hydrogen generated, the system controller 12, for example, generates the fuel generating member 1 whose remaining amount of iron is 100% during power generation of the fuel cell unit 2. The gas circulation amount of the pump 8 may be controlled so as to be equal to or less than the minimum value Vmin (100%) of the gas circulation amount range of the pump 8 at which the amount of generated fuel gas is maximized. As a result, it is possible to prevent an increase in the amount of gas circulation that does not lead to an increase in the amount of hydrogen generation, regardless of the value of the ratio (the remaining amount of iron) in which the fuel generating member 1 does not undergo the oxidation reaction.

  In consideration of the relationship between the ratio of the fuel generating member not undergoing the oxidation reaction and the amount of hydrogen generated, the system controller 12 determines that the amount of fuel gas generated in the fuel generating member 1 is, for example, during power generation of the fuel cell unit 2. The gas circulation amount of the pump 8 may be controlled so that the minimum value Vmin of the gas circulation amount range of the pump 8 which is maximized is changed according to the remaining amount of iron and becomes the minimum value Vmin or less. As a result, it is possible to prevent an increase in the amount of gas circulation that does not lead to an increase in the amount of hydrogen generation, and to obtain the maximum amount of hydrogen generation corresponding to the remaining amount of iron. The remaining amount of iron can be obtained from, for example, the weight of the fuel generating member 1, and can also be obtained, for example, from each integrated value of the generated current and the electrolysis current of the fuel cell unit 2.

  Next, a procedure for determining the configuration of the fuel generating member 1 will be described.

  First, the specification of the power generation amount of the fuel cell unit 2 is determined from the specification of the output of the fuel cell system according to the present embodiment, and then the specification of the output of the pump 8 is determined from the specification of the power generation amount of the fuel cell unit 2. . Then, the total amount of the fuel generating member 1 is determined from the specification of the power generation duration of the fuel cell system according to the present embodiment. If the normal range of the output of the pump 8 determined in advance is relatively small, the amount of hydrogen generation increases when the pellets 13 are made smaller, so that the power generation efficiency becomes higher. On the contrary, if the normal range of the output of the pump 8 is relatively large, the larger the pellet 13 is, the more hydrogen is generated, and thus the power generation efficiency is increased. Therefore, in the fuel cell system according to this embodiment, the pump 8 in which the amount of fuel gas generated in the fuel generating member 1 is maximized when the amount of gas circulation corresponding to the normal range of the output of the pump 8 is generated by the fuel cell unit 2. The size of the pellet 13 is determined so as to be equal to or less than the minimum value of the gas circulation amount range.

  For example, the relationship between the gas circulation amount range of the pump 8 and the hydrogen generation amount in the fuel generating member 1 is separately measured in advance with only the fuel generating member 1 as a measurement target, and the system controller 12 stores the measurement data. A water vapor detector (dew point meter), pressure gauge, thermometer, etc. may be provided on the gas circulation path of the fuel cell system according to this embodiment, and the pressure of the circulating gas, water vapor concentration, hydrogen concentration during preliminary operation, etc. The system controller 12 may acquire the information by detecting the above.

  In the above-described embodiment, the system controller 12 is configured so that the power generation amount of the fuel cell 1 is equal to or less than the minimum value of the gas circulation amount range of the pump 8 at which the fuel gas generation amount in the fuel generation member 1 is maximized. Although the gas circulation amount of the pump 8 is controlled, according to the same technical idea, the pump 8 is configured so that, when the fuel generation member 1 is regenerated, the water vapor generation amount becomes the maximum value of the gas circulation amount range of the pump 8 that is the maximum. The gas circulation amount may be controlled. Control of the system controller 12 during regeneration of the fuel generating member 1 can prevent an increase in the amount of gas circulation that does not lead to an increase in the amount of water vapor generated. Therefore, when the fuel generating member 1 is regenerated, unnecessary energy is not consumed for driving the pump 8, and energy efficiency can be increased.

  In addition, it is a viewpoint which makes energy efficiency still higher that both control of the system controller 12 at the time of the electric power generation of the fuel cell part 2 mentioned above and control of the system controller 12 at the time of the regeneration of the fuel generating member 1 mentioned above are performed. However, it is possible that only one of them is performed.

  Moreover, the form of the container which accommodates the fuel generation member 1 is not limited to each example in embodiment mentioned above. For example, as shown in FIG. 12, the container 5 may include a partition plate 26 for elongating the gas flow path, and may accommodate the pellets 13 constituting the fuel generating member 1.

  Moreover, although the fuel generation member 1 was comprised with the pellet in embodiment mentioned above, this invention does not limit the form of the fuel generation member 1 to a pellet. For example, the structure 27 in which the gas flow path shown in FIG. 13 is formed may be used as the fuel generating member 1. The structure 27 has a honeycomb structure in which the cross-sectional shape of the gas flow path is a regular hexagon, but the cross-sectional shape of the gas flow path may be other shapes. The structure 27 may be, for example, a molded body obtained by solidifying the Fe fine particles while leaving a space that allows gas to pass. For example, the structure 27 is formed of a porous member, as shown in FIG. In addition, the Fe fine particles 30 may be disposed in a space 29 provided in the porous member 28.

  When the structure 27 is used as the fuel generating member 1, the thickness of the wall (a part of the structure 27) interposed between the gas flow paths acts on the gas flow in the same manner as the size of the pellet. The hydrogen generation amount characteristic at the time of power generation in the part 2 or the water vapor generation amount characteristic at the time of regeneration of the fuel generation member 1 has the same tendency as in the case of pellets.

  In the embodiment described above, a solid oxide electrolyte is used as the electrolyte membrane 2A of the fuel cell unit 2, and water is generated on the fuel electrode 2B side during power generation. According to this configuration, water is generated on the side where the fuel generating member 1 is provided, which is advantageous for simplification and miniaturization of the apparatus. On the other hand, as a fuel cell disclosed in Japanese Patent Application Laid-Open No. 2009-99491, a solid polymer electrolyte that allows hydrogen ions to pass through may be used as the electrolyte membrane 2A of the fuel cell unit 2. However, in this case, since water is generated on the air electrode 2C side that is the oxidant electrode of the fuel cell unit 2 during power generation, a flow path for propagating this water to the fuel generating member 1 is provided. Just do it. In the above-described embodiment, one fuel cell unit 2 performs both power generation and water electrolysis. However, a fuel cell (for example, a solid oxide fuel cell dedicated to power generation) and a water electrolyzer (for example, water) A solid oxide fuel cell dedicated for electrolysis may be connected to the fuel generating member 1 in parallel on the gas flow path.

  In the above-described embodiment, the fuel gas of the fuel cell unit 2 is hydrogen. However, a reducing gas other than hydrogen, such as carbon monoxide or hydrocarbon, may be used as the fuel gas of the fuel cell unit 2.

  In the above-described embodiment, air is used as the oxidant gas, but an oxidant gas other than air may be used.

DESCRIPTION OF SYMBOLS 1 Fuel generating member 2 Fuel cell part 2A Electrolyte membrane 2B Fuel electrode 2C Air electrode 3, 4 Heater 5, 6 Container 7, 10, 11 Piping 8 Pump 9 Thermal insulation container 12 System controller 13 Pellet 22 Circulating gas flow of the whole several containers Inlet 23 Circulating gas outlet of the entire plurality of containers 26 Partition plate 27 Structure 28 Porous member 29 Space 30 Fe fine particles

Claims (6)

A fuel generating member that generates fuel gas by a chemical reaction;
A fuel cell unit that generates power using the fuel gas supplied from the fuel generating member;
A gas flow path for circulating gas between the fuel generating member and the fuel cell unit;
A circulator which is provided on the gas flow path and forcibly circulates a gas between the fuel generating member and the fuel cell unit;
Circulation for controlling the gas circulation amount of the circulator so that the amount of fuel gas generated in the fuel generating member is not more than the minimum value of the gas circulation amount range of the circulator when generating power in the fuel cell unit. A fuel cell system comprising a vessel controller. A fuel generating member that generates fuel gas by a chemical reaction, and that can be regenerated by a reverse reaction of the chemical reaction;
A power generation function for generating power using the fuel gas supplied from the fuel generation member; and an electrolysis function for electrolyzing the product of the reverse reaction supplied from the fuel generation member during regeneration of the fuel generation member. Power generation / electrolysis section,
A gas flow path for circulating gas between the fuel generating member and the power generation / electrolysis unit;
When the fuel generating member is regenerated, the gas in the circulator is set so that the amount of the product of the reverse reaction generated in the fuel generating member is equal to or less than the minimum value in the gas circulation amount range of the circulator. A fuel cell system, comprising: a circulator control unit that controls a circulation amount.   The circulation controller controls the circulation so that the amount of fuel gas generated in the fuel generation member becomes the maximum value of the gas circulation amount range of the circulator when the power generation / electrolysis unit generates power. The fuel cell system according to claim 2, wherein the amount of gas circulation in the vessel is controlled. The fuel generating member is formed of fine particles,
The fuel cell system according to claim 1, wherein the fine particles have a metal that generates fuel gas by the chemical reaction as a base material. The fuel generating member is formed of fine particles,
4. The fuel cell system according to claim 2, wherein the fine particles generate a fuel gas by the chemical reaction and use a metal that can be regenerated by the reverse reaction as a base material. 5.   The fuel cell system according to any one of claims 1 to 5, wherein the fuel generating member is accommodated in a plurality of containers.