JP2005310430A - Operation method of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell in which local ionization reaction of hydrogen does not occur in an anode electrode part constituting a fuel electrode and in which life prolongation is achieved. <P>SOLUTION: This is a method in which a unit battery composed by interposing an electrolyte between the fuel electrode into which a fuel containing hydrogen as the main component is supplied, and an air electrode into which air is supplied as an oxidizer, drives a plurally-laminated fuel cell. In this driving method, a mole number of oxygen contained in the air supplied into the air electrode is controlled so as to be one half or less to the mole number of hydrogen contained in the fuel supplied into the fuel electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of operating a fuel cell in which the life of the fuel cell is extended by causing uniform ionization reaction of hydrogen in a fuel electrode, and a fuel cell power generation apparatus and a fuel cell power generation system that realize the method.

  A fuel cell is an apparatus with excellent energy conversion efficiency that can directly convert the chemical energy of fuel into electrical energy electrochemically without burning. In particular, a fuel cell that supplies hydrogen as fuel to the fuel electrode (anode electrode) side and uses oxygen in the air on the air electrode (cathode electrode) side generates water by the reaction of hydrogen and oxygen during energy generation. Because it does not generate carbon dioxide, nitrogen oxides, sulfur oxides, etc., as in the case of devices that generate energy by burning fossil fuels such as oil and coal, it does not lead to an increase in environmental impact. Expectations are high as a clean energy source.

In a fuel cell, a fuel electrode that is brought into contact with hydrogen (fuel) and an air electrode that is brought into contact with oxygen (air, oxidant) sandwich an electrolyte. The electrolyte is disposed in the form of a polymer ion exchange membrane (solid polymer fuel cell), a matrix containing phosphoric acid (phosphoric acid fuel cell), or the like. In a fuel cell, when hydrogen is supplied to the fuel electrode, it dissociates into hydrogen ions and electrons, and the dissociated electrons move to the air electrode side through an external circuit, and at the air electrode, hydrogen that has moved in the electrolyte. The ions and electrons from the external circuit react with oxygen to produce water. Electric power is generated by such a reaction (see, for example, Patent Document 1 regarding a phosphoric acid fuel cell).
Reaction of anode: 2H ₂ → 4H ⁺ + 4e
Reaction at the air electrode: O ₂ + 4H ⁺ + 4e → 2H ₂ O
Japanese Patent Laid-Open No. 9-55219

  In such a fuel cell, there is a problem to be solved that the lifetime is short. As a result of investigations, it was considered that the occurrence of a local overload at the fuel electrode was one of the causes of short life. Conventionally, in a fuel cell, since the production of hydrogen as a fuel is expensive compared to an oxidant that can use air, in order to efficiently use hydrogen, excess oxygen (air) ) Is being supplied. Therefore, hydrogen supplied to the fuel cell is always in an ionizable state, and is immediately ionized when supplied in the vicinity of the inlet of the fuel electrode, causing an ionization reaction locally (polarization occurs). Due to this phenomenon, a load is applied to a part of the anode electrode constituting the fuel electrode, so that the deterioration of the electrode member and the electrolyte is locally accelerated.

  In particular, in general fuel cells, since the output per unit cell is less than 1 V, 400 to 500 unit cells are connected in series in order to obtain, for example, 400 V that is usually used in a factory. Must be configured as a battery. Therefore, it is necessary to distribute hydrogen evenly to 400 to 500 cells. However, since this is very difficult, local load is likely to occur at the fuel electrode, and the life is shortened accordingly. It was thought that

  The present invention has been made in view of the above-described problems, and the object of the present invention is to prevent a local hydrogen ionization reaction from occurring in the anode electrode portion constituting the fuel electrode and to extend the life. It is to provide a fuel cell. As a result of repeated research, a relatively sufficient amount of hydrogen relative to the amount of oxygen was introduced into the fuel electrode of the fuel cell, and the hydrogen was distributed to the electrolyte and fuel electrode. It has been found that the above object can be achieved by means of generating electricity by supplying a relatively small amount of oxygen (air) relative to the amount of hydrogen while controlling the flow rate. In other words, what determines the rate of power generation is not the amount of hydrogen but the amount of oxygen, and there is sufficient hydrogen ions in the electrolyte so that a certain amount of unreacted hydrogen is always discharged from the fuel cell. In this state, power is generated by introducing a relatively small amount of oxygen relative to the amount of hydrogen. Thereby, the polarization of hydrogen at the fuel electrode, which has been conventionally generated, is prevented, and the life of the fuel cell can be extended. More specifically, the present invention provides the following means.

  That is, according to the present invention, a plurality of single cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked. A method for operating a fuel cell, wherein oxygen contained in air supplied to the air electrode is less than half of the number of moles of hydrogen contained in fuel supplied to the fuel electrode. A fuel cell operation method for controlling the number of moles is also provided (also referred to as a first fuel cell operation method).

  In addition, according to the present invention, a plurality of unit cells in which an electrolyte is interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked. A method for operating a fuel cell, wherein the moles of oxygen contained in the air supplied to the air electrode are set so that the number of moles of unreacted hydrogen contained in the fuel discharged from the fuel electrode becomes equal to or greater than a certain value. A fuel cell operation method for controlling the number is also provided (also referred to as a second fuel cell operation method).

  Furthermore, according to the present invention, a plurality of single cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked. A module battery, and a method of operating a fuel cell configured by connecting a plurality of module batteries, wherein the temperature of a plurality of module batteries is individually measured, and the temperature difference between them is below a certain level Thus, there is provided a fuel cell operation method for controlling the number of moles of oxygen contained in the air supplied to the air electrode (also referred to as a third fuel cell operation method).

  Still further, according to the present invention, there are provided a plurality of unit cells in which an electrolyte is interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant. A method of operating a fuel cell in which a plurality of module cells are connected by stacking to form a module cell, and the voltage of the plurality of module cells is individually measured and the voltage difference between them is constant A fuel cell operation method for controlling the number of moles of oxygen contained in the air supplied to the air electrode is provided as follows (also referred to as a fourth fuel cell operation method).

  Still further, according to the present invention, there are provided a plurality of unit cells in which an electrolyte is interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant. A method of operating stacked fuel cells, in which the temperature of single cells is measured individually, and the molarity of oxygen contained in the air supplied to the air electrode is such that the temperature difference between them is less than a certain value. A fuel cell operation method for controlling the number is also provided (also referred to as a fifth fuel cell operation method).

  Still further, according to the present invention, there are provided a plurality of unit cells in which an electrolyte is interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant. A method of operating a stacked fuel cell, in which the voltage of a single cell is measured individually, and the molarity of oxygen contained in the air supplied to the air electrode so that the voltage difference between them is less than a certain value. A fuel cell operation method for controlling the number is also provided (also referred to as a sixth fuel cell operation method).

  According to the present invention, a plurality of single cells having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked. Fuel cell, supply hydrogen amount measuring means for measuring the number of moles of hydrogen contained in the fuel supplied to the fuel electrode, and supply oxygen amount control means for controlling the number of moles of oxygen contained in the air supplied to the air electrode Are provided (also referred to as a first fuel cell power generator).

  In addition, according to the present invention, a plurality of unit cells in which an electrolyte is interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked. A fuel cell, an exhaust hydrogen amount measuring means for measuring the number of moles of unreacted hydrogen contained in the fuel discharged from the fuel electrode, and a number of moles of oxygen contained in the air supplied to the air electrode And a supply oxygen amount control unit (hereinafter also referred to as a second fuel cell power generation device).

  Furthermore, according to the present invention, a plurality of single cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked. A module battery, a plurality of module batteries connected to each other, a temperature difference measuring means for measuring a temperature difference between the plurality of module batteries, and air supplied to the air electrode And a supply oxygen amount control means for controlling the number of moles of oxygen to be supplied (also referred to as a third fuel cell power generation apparatus).

  Still further, according to the present invention, there are provided a plurality of unit cells in which an electrolyte is interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant. A module battery is formed by stacking and a plurality of module batteries are connected, a voltage difference measuring means for measuring a voltage difference between the plurality of module batteries, and air supplied to the air electrode There is provided a fuel cell power generator comprising a supply oxygen amount control means for controlling the number of moles of oxygen contained (also referred to as a fourth fuel cell power generator).

  Still further, according to the present invention, a plurality of single cells each having an electrolyte interposed are connected between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant. A fuel cell, a temperature difference measuring means for measuring a temperature difference between the unit cells, and a supply oxygen amount control means for controlling the number of moles of oxygen contained in the air supplied to the air electrode A battery power generator is provided (also referred to as a fifth fuel cell power generator).

  Still further, according to the present invention, a plurality of single cells each having an electrolyte interposed are connected between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant. A fuel cell, a voltage difference measuring means for measuring a voltage difference between the single cells, and a supply oxygen amount control means for controlling the number of moles of oxygen contained in the air supplied to the air electrode A battery power generator is provided (also referred to as a sixth fuel cell power generator).

  According to the present invention, a calcination furnace comprising: combustion means for burning a fuel containing methane to generate combustion gas; and a calcination furnace main body for calcination of an object to be baked into the interior by the combustion gas; The reformed raw material, which is filled with a catalyst and is made of methane-containing fuel and steam, is brought into contact with the methane reforming catalyst while being heated, thereby reacting the methane and steam in the reformed raw material. And a reformer for generating a reformed gas composed of hydrogen and carbon dioxide, and any one of the first to sixth fuel cell power generators. Using the exhaust heat of the generated combustion gas, a reformer containing hydrogen is generated in the reformer, and the reformed gas is used as fuel for the fuel cell to generate power, and is further discharged from the fuel cell. Unreacted reformed gas By combusting a fee, along with effective use of the reformed gas containing hydrogen, the fuel cell power generation system is provided for converting a portion of the thermal energy of the combustion gas into electrical energy.

  In the fuel cell power generation system according to the present invention, hydrogen in the reformed gas generated by the reformer is selectively separated into a fuel containing hydrogen as a main component and a residual gas containing carbon dioxide. And a hydrogen separator for separating the reformed gas containing hydrogen generated by the reformer into hydrogen and carbon dioxide by the hydrogen separator, and replacing the reformed gas with hydrogen in the fuel cell. By generating electricity using it as fuel and burning unreacted hydrogen discharged from the fuel cell as fuel for the combustion means, hydrogen can be used effectively, and part of the thermal energy of the combustion gas can be converted into electrical energy. It is preferable to convert.

  According to the first fuel cell operating method of the present invention, the air supplied to the air electrode is reduced to 1/2 or less of the number of moles of hydrogen contained in the fuel supplied to the fuel electrode. Since the number of moles of oxygen contained is controlled, abundant hydrogen ions are present in the electrolyte at the air electrode. Therefore, local ionization reaction of hydrogen does not occur in the anode electrode portion constituting the fuel electrode, and it is possible to prevent a short life due to deterioration of the electrode member or the like.

  The first fuel cell power generator according to the present invention includes a supply hydrogen amount measuring means for measuring the number of moles of hydrogen contained in the fuel supplied to the fuel electrode, and a mole of oxygen contained in the air supplied to the air electrode. And a supply oxygen amount control means for controlling the number, so that the operation method of the first fuel cell according to the present invention can be implemented, and through the implementation, the fuel electrode is filled with unreacted hydrogen, The local ionization reaction of hydrogen does not occur in the anode electrode portion, and the life of the fuel cell can be extended.

  According to the second method of operating the fuel cell according to the present invention, it is included in the air supplied to the air electrode so that the number of moles of unreacted hydrogen contained in the fuel discharged from the fuel electrode becomes a certain value or more. Since the number of moles of oxygen generated is controlled, the fuel electrode can be more directly filled with unreacted hydrogen, and a local ionization reaction of hydrogen does not occur in the anode electrode portion constituting the fuel electrode. It is possible to prevent shortening of the service life due to deterioration of the electrode member.

  The second fuel cell power generator according to the present invention is included in the discharged hydrogen amount measuring means for measuring the number of moles of unreacted hydrogen contained in the fuel discharged from the fuel electrode, and in the air supplied to the air electrode. And a supply oxygen amount control means for controlling the number of moles of oxygen, so that the operation method of the second fuel cell according to the present invention can be implemented, and through the implementation, the fuel electrode is unreacted more directly. It can be filled with hydrogen, and a local ionization reaction of hydrogen does not occur in the anode electrode portion constituting the fuel electrode, so that the life of the fuel cell can be extended.

  According to the third fuel cell operation method of the present invention, the temperature of the plurality of module cells is individually measured, and the air supplied to the air electrode is adjusted so that the temperature difference between them is below a certain level. Since the number of moles of oxygen contained is controlled, local ionization reaction of hydrogen in the anode electrode portion constituting the fuel electrode can be prevented, and the life shortening due to deterioration of the electrode member or the like can be prevented.

  A third fuel cell power generator according to the present invention includes a temperature difference measuring means for measuring a temperature difference between a plurality of module cells, and a supply oxygen for controlling the number of moles of oxygen contained in the air supplied to the air electrode. The third fuel cell operating method according to the present invention, and indirectly through the implementation, the local hydrogen ionization reaction at the anode electrode portion constituting the fuel electrode. Can be prevented, and the life of the fuel cell can be extended.

  According to the fourth fuel cell operating method of the present invention, the voltages of the plurality of module cells are individually measured, and the air supplied to the air electrode is adjusted so that the voltage difference between them is less than a certain value. Since the number of moles of oxygen contained is controlled, local ionization reaction of hydrogen in the anode electrode portion constituting the fuel electrode can be prevented, and the life shortening due to deterioration of the electrode member or the like can be prevented.

  A fourth fuel cell power generator according to the present invention comprises a voltage difference measuring means for measuring a voltage difference between a plurality of module cells, and a supply oxygen for controlling the number of moles of oxygen contained in the air supplied to the air electrode. The fourth fuel cell operation method according to the present invention, and indirectly through the implementation, the local hydrogen ionization reaction in the anode electrode portion constituting the fuel electrode. Can be prevented, and the life of the fuel cell can be extended.

  According to the fifth fuel cell operating method of the present invention, the temperatures of the unit cells are individually measured, and the temperature difference between them is included in the air supplied to the air electrode so as to be a certain value or less. Since the number of moles of oxygen is controlled, local ionization reaction of hydrogen in the anode electrode portion constituting the fuel electrode can be prevented, and shortening of the life due to deterioration of the electrode member can be prevented.

  The fifth fuel cell power generator according to the present invention includes a temperature difference measuring means for measuring a temperature difference between the cells, and a supply oxygen amount control for controlling the number of moles of oxygen contained in the air supplied to the air electrode. Therefore, the fifth fuel cell operating method according to the present invention can be implemented, and through this implementation, local ionization reaction of hydrogen in the anode electrode portion constituting the fuel electrode is indirectly prevented. And the life of the fuel cell can be extended.

  According to the sixth method of operating a fuel cell according to the present invention, the voltages of the single cells are individually measured, and are included in the air supplied to the air electrode so that the voltage difference between them is below a certain level. Since the number of moles of oxygen is controlled, local ionization reaction of hydrogen in the anode electrode portion constituting the fuel electrode can be prevented, and shortening of the life due to deterioration of the electrode member or the like can be prevented.

  A sixth fuel cell power generator according to the present invention includes a voltage difference measuring means for measuring a voltage difference between the cells, and a supply oxygen amount control for controlling the number of moles of oxygen contained in the air supplied to the air electrode. The sixth fuel cell operating method according to the present invention can be implemented, and through this implementation, a local hydrogen ionization reaction in the anode electrode portion constituting the fuel electrode is indirectly prevented. And the life of the fuel cell can be extended.

  The fuel cell power generation system according to the present invention generates a reformed gas containing hydrogen in a reformer by using a part of heat of combustion gas generated in a firing furnace body, and uses the reformed gas as a fuel cell. As a fuel for generating electricity, the unreacted reformed gas discharged from the fuel cell is burned as the fuel for the combustion means, so that the reformed gas containing hydrogen can be used effectively and the combustion gas has Since a part of the thermal energy is converted into electric energy, the carbon dioxide content in the combustion gas can be greatly reduced, and the total amount of fuel used can be reduced. Also, in the fuel cell, the amount of oxygen that reacts with hydrogen contained in the reformed gas is relatively reduced, and as a result of the operation in which the amount of oxygen becomes the rate-limiting of power generation, hydrogen is contained from the fuel cell. Even if the reformed gas to be discharged is discharged without being reacted, it is possible to extend the life of the fuel cell by operating such a fuel cell.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. However, the present invention should not be construed as being limited to these, and those skilled in the art will be able to do so without departing from the scope of the present invention. Various changes, modifications and improvements can be made based on the knowledge. For example, the drawings show preferred embodiments of the present invention, but the present invention is not limited by the modes shown in the drawings or the information shown in the drawings. In practicing or verifying the present invention, means similar to or equivalent to those described in the present specification can be applied, but preferred means are those described below.

  The first fuel cell power generator according to the present invention can implement the operation method of the first fuel cell according to the present invention, and exhibits an effect through the implementation. The first fuel cell according to the present invention. This operating method is not only realized by the first fuel cell power generator according to the present invention, and the first fuel cell operating method is an invention that exists independently of the first fuel cell power generator. is there. The relationship between the second fuel cell operating method and the second fuel cell power generator, the relationship between the third fuel cell operating method and the third fuel cell power generator, the fourth fuel cell operating method and the first 4, the relationship between the fuel cell power generation device, the fifth fuel cell operation method and the fifth fuel cell power generation device, the relationship between the sixth fuel cell operation method and the sixth fuel cell power generation device, The same applies to.

  The operation methods of the first to sixth fuel cells according to the present invention and the first to sixth fuel cell power generators according to the present invention do not limit the type of the fuel cell. The present invention can be applied to various fuel cells such as phosphoric acid fuel cells, solid polymer fuel cells, molten carbonate fuel cells, and solid electrolyte fuel cells. In the former two cases, high-purity hydrogen is required as the fuel. Therefore, it is necessary to supply a fuel suitable for this, but such conditions do not affect the essence of the present invention. In the present specification, it is expressed as a fuel containing hydrogen as a main component. However, in the case of a phosphoric acid fuel cell and a solid polymer fuel cell, the fuel is composed only of high-purity hydrogen, and on the other hand, molten carbon dioxide. In the salt type fuel cell and the solid oxide type fuel cell, any fuel that has a high proportion of hydrogen may be used.

FIG. 1 is a schematic configuration diagram of a fuel cell for explaining a technical idea common to the first to sixth fuel cell operating methods according to the present invention, and FIG. 2 shows a conventional fuel cell operating method. It is a schematic block diagram of the fuel cell for demonstrating. A fuel cell is formed by interposing an electrolyte between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant (actually, a plurality of unit cells are stacked). When hydrogen is supplied to the fuel electrode, it dissociates into hydrogen ions (H ⁺ ) and electrons (e), and the dissociated electrons pass through an external path. As the air electrode moves to the air electrode side, hydrogen ions that have passed through the electrolyte react with electrons from the external circuit and oxygen to produce water. Electricity is generated by such a reaction, for example, a light bulb is energized and brightened.

  The technical concept common to the operating methods of the first to sixth fuel cells according to the present invention, and the technical feature that clearly shows the contribution to the prior art, is that a sufficient amount of hydrogen is relative to the amount of oxygen. Put the fuel cell in the fuel electrode, let the fuel cell spread through the electrolyte and fuel electrode, and control the flow rate of a relatively small amount of oxygen (air) relative to the amount of hydrogen to the air electrode. , To generate electricity (see FIG. 1). That is, in the past, oxygen as an oxidizer can use air that is generally inexpensive, but the production of hydrogen as a fuel is costly, so in order not to waste any amount of hydrogen, the amount of hydrogen is reduced. Compared to the operation of supplying excess oxygen (air) (see FIG. 2), the present invention controls the amount of oxygen instead of the amount of hydrogen to control the power generation. There are features. A relatively small amount of oxygen should be introduced relative to the amount of hydrogen in a state where hydrogen ions are sufficiently distributed in the electrolyte so that a certain amount or more of unreacted hydrogen is always discharged from the fuel cell. Prevents local ionization of hydrogen.

  FIG. 4 is a schematic configuration diagram showing an embodiment of a first fuel cell power generator according to the present invention. In the fuel cell 40, an electrolyte 41 is interposed between a fuel electrode 42 and an air electrode 43 (actually, a plurality of single cells are stacked). A fuel containing hydrogen 1 as a main component is supplied to the fuel electrode 42, and oxygen 2 (air) is supplied to the air electrode 43 as an oxidant.

  The supply system of hydrogen 1 (fuel) is provided with supply hydrogen amount measuring means including, for example, a fuel flow meter 11, a hydrogen concentration meter 12, and a computing device 15, and hydrogen 1 contained in the fuel supplied to the fuel electrode 42. Measure the number of moles (substance amount). Further, the supply system of oxygen 2 is provided with supply oxygen amount control means including, for example, a controller 13 (or control device) and a control valve 14, and the number of moles of oxygen 2 contained in the air supplied to the air electrode 43. (Substance amount) is controlled. Usually, since the amount of oxygen in the air is constant, the number of moles of oxygen 2 can be controlled by controlling the flow rate of air.

Since the reaction at the air electrode 43 is (O ₂ + 4H ⁺ + 4e → 2H ₂ O), it is a reaction in which 2 mol of hydrogen per 1 mol of oxygen. Therefore, the number of moles of hydrogen 1 contained in the fuel supplied to the fuel electrode 42 measured by the fuel flow meter 11, the hydrogen concentration meter 12, and the arithmetic unit 15 is sent to the controller 13, and the mole number of hydrogen 1 is calculated. Therefore, oxygen contained in the air supplied to the air electrode 43 is directly controlled by the control valve 14 so as to be less than 1/2, preferably less than 1/2. By controlling the number of moles of 2 (the operation method of the first fuel cell according to the present invention), this reaction is regulated by oxygen 2. Hydrogen 1 that does not have oxygen 2 as a reaction partner fills the fuel cell 40 and is discharged from the fuel electrode 42 as unreacted hydrogen 3. On the other hand, water 4 (H ₂ O) produced as a result of the reaction is also discharged out of the system from the air electrode 43.

Next, FIG. 5 is a schematic configuration diagram showing an embodiment of a second fuel cell power generator according to the present invention. The fuel cell 50 is formed by interposing an electrolyte 41 between a fuel electrode 42 and an air electrode 43 (actually, a plurality of unit cells are stacked). A fuel containing hydrogen 1 as a main component is supplied to the fuel electrode 42, and unused fuel containing unreacted hydrogen 3 is discharged from the fuel electrode 42. To the air electrode 43, oxygen 2 (air) is supplied as an oxidizing agent, from the air electrode 43, reaction ^{_{(O 2 + 4H + + 4e}} → 2H 2 O) results, generated water 4 (H ₂ O) is discharged Is done.

  The discharge system of the unreacted hydrogen 3 (unused fuel) is provided with a discharge hydrogen amount measuring means including, for example, an unused fuel flow meter 21, a hydrogen concentration meter 22, and an arithmetic unit 45, and is discharged from the fuel electrode 42. The number of moles (substance amount) of unreacted hydrogen 3 contained in the unused fuel is measured. Further, the supply system of oxygen 2 is provided with supply oxygen amount control means including, for example, a controller 23 (or control device) and a control valve 14, and the number of moles of oxygen 2 contained in the air supplied to the air electrode 43. (Substance amount) is controlled. Usually, since the amount of oxygen in the air is constant, the number of moles of oxygen 2 can be controlled by controlling the flow rate of air.

  In the fuel cell 50, maintaining the state in which the number of moles of the unreacted hydrogen 3 is detected above a certain level means that the fuel cell 50 is filled with hydrogen 1 that does not contain oxygen 2 as a reaction partner. Indirect confirmation. Accordingly, the number of moles of unreacted hydrogen 3 contained in the unused fuel discharged from the fuel electrode 42 measured by the unused fuel flow meter 21, the hydrogen concentration meter 22, and the arithmetic unit 45 is sent to the controller 23. The flow rate of air is directly controlled by the control valve 14 so that the number of moles of the reaction hydrogen 3 becomes a certain value or more, and the number of moles of oxygen 2 contained in the air supplied to the air electrode 43 is controlled. (Second fuel cell operation method according to the present invention) prevents local ionization reaction of hydrogen. It should be noted that the constant value over the specific number of moles of the unreacted hydrogen 3 is not a zero value and is not limited, and is arbitrary in consideration of the accuracy of the equipment constituting the discharged hydrogen amount measuring means. It is a numerical value that should be determined.

Next, FIG. 6 is a schematic configuration diagram showing an embodiment of a third fuel cell power generator according to the present invention. The fuel cell 60 includes a plurality of (three in this example) module cells 80 each having an electrolyte 51 interposed between a fuel electrode 52 and an air electrode 53 (actually, the module cell further includes a single cell. A plurality of layers). A fuel containing hydrogen 1 as a main component is supplied to each fuel electrode 52 of each module battery 80, and unused fuel containing unreacted hydrogen 3 is discharged from each fuel electrode 52. Is to each of the air electrode 53, oxygen 2 (air) is supplied as an oxidizing agent, from the air electrode 53, reaction ^{_{(O 2 + 4H + + 4e}} → 2H 2 O) results, generated water 4 (H ₂ O) Is discharged.

  Each of the module batteries 80 is provided with a temperature difference measuring means composed of thermometers 31, 32, 33 for measuring the respective temperatures and the arithmetic unit 26. The oxygen 2 supply system includes, for example, a controller 24 (or control device) and a plurality of (three in this example) control valves 14 provided for each system to each air electrode 53 of each module battery 80. Is provided, and controls the number of moles (substance amount) of oxygen 2 contained in the air supplied to each air electrode 53. Usually, since the amount of oxygen in the air is constant, the number of moles of oxygen 2 can be controlled by controlling the flow rate of air.

  In the fuel cell 60, when a local ionization reaction of hydrogen occurs, current concentrates on the ionization reaction, resulting in an increase in temperature. That is, maintaining a state in which the temperature difference among the plurality of module batteries 80 is below a certain level indirectly confirms that no local hydrogen ionization reaction has occurred. Therefore, the temperature difference between the module batteries 80 measured by the thermometers 31, 32, 33 and the arithmetic unit 26 is sent to the controller 24, and each control valve 14 is directly connected so that the temperature difference becomes below a certain value. By controlling the flow rate of air by controlling the number of moles of oxygen 2 contained in the air supplied to any one of the air electrodes 53 (the third fuel cell operation method according to the present invention) Hydrogen ionization reaction is prevented.

  The constant value below a certain value related to the temperature difference between the plurality of module batteries 80 is a numerical value determined based on operational experience and is not limited, and the module battery during stable operation of the fuel cell is not limited. It is a numerical value determined in consideration of the maximum temperature difference. The determination that the temperature difference is equal to or less than a certain value is not simply a measurement of the temperature difference between the plurality of module batteries 80, but the average temperature of the plurality of module batteries 80 is obtained and the module battery 80 having a large deviation from the average value is obtained. It is possible to take measures such as controlling the air flow rate. Further, instead of measuring the temperature difference between the plurality of module batteries 80, the temperature of the unit cells is measured individually, the temperature difference between them is obtained, and each unit cell is included in the supplied air. The number of moles of oxygen 2 produced can be controlled (fifth fuel cell operation method according to the present invention).

Next, FIG. 7 is a schematic configuration diagram showing an embodiment of a fourth fuel cell power generator according to the present invention. The fuel cell 70 is provided with a plurality (three in this example) of module batteries 80 each having an electrolyte 51 interposed between the fuel electrode 52 and the air electrode 53 (in practice, the module battery further includes single cells. A plurality of layers). A fuel containing hydrogen 1 as a main component is supplied to each fuel electrode 52 of each module battery 80, and unused fuel containing unreacted hydrogen 3 is discharged from each fuel electrode 52. Is to each of the air electrode 53, oxygen 2 (air) is supplied as an oxidizing agent, from the air electrode 53, reaction ^{_{(O 2 + 4H + + 4e}} → 2H 2 O) results, generated water 4 (H ₂ O) Is discharged.

  Each of the module batteries 80 is provided with voltage difference measuring means including voltmeters 34, 35, 36 for measuring the respective voltages and an arithmetic unit 27. The oxygen 2 supply system includes, for example, a controller 25 (or a control device) and a plurality of (three in this example) control valves 14 provided for each system to each air electrode 53 of each module battery 80. Is provided, and controls the number of moles (substance amount) of oxygen 2 contained in the air supplied to each air electrode 53. Usually, since the amount of oxygen in the air is constant, the number of moles of oxygen 2 can be controlled by controlling the flow rate of air.

  When a local hydrogen ionization reaction occurs in the fuel cell 70, the voltage of the corresponding module cell 80 increases. That is, maintaining a state in which the voltage difference between the plurality of module batteries 80 is below a certain level indirectly confirms that no local hydrogen ionization reaction has occurred. Accordingly, the voltage difference between the module batteries 80 measured by the voltmeters 34, 35, and 36 and the arithmetic unit 27 is sent to the controller 25, and each control valve 14 is directly connected so that this voltage difference becomes a certain value or less. By controlling the flow rate of air by controlling the number of moles of oxygen 2 contained in the air supplied to any one of the air electrodes 53 (fourth fuel cell operation method according to the present invention) Hydrogen ionization reaction is prevented.

  The constant value below a certain value related to the voltage difference between the plurality of module batteries 80 is a numerical value determined based on operational experience, and is not limited, and is not limited between module batteries during stable operation of the fuel cell. It is a numerical value determined in consideration of the maximum voltage difference. The determination that the voltage difference is equal to or less than a certain value is not simply a measurement of the voltage difference between the plurality of module batteries 80, but an average voltage of the plurality of module batteries 80 is obtained and the module battery 80 having a large deviation from the average value is obtained. It is possible to take measures such as controlling the air flow rate. Furthermore, instead of measuring the voltage difference between the plurality of module batteries 80, the voltage of the unit cells is measured individually, the voltage difference between them is obtained, and each unit cell is included in the supplied air. The number of moles of oxygen 2 can be controlled (sixth fuel cell operation method according to the present invention).

  The first to sixth fuel cell operating methods according to the present invention and the first to sixth fuel cell power generators according to the present invention have been described above. In these inventions, the life of the fuel cell is extended. However, since unreacted hydrogen (unused fuel) will increase compared to the prior art, it is necessary to make effective use of this. Hereinafter, a fuel cell power generation system capable of effectively using unreacted hydrogen will be described.

  FIG. 3 is a schematic configuration diagram showing an embodiment of a fuel cell power generation system according to the present invention. The fuel cell power generation system includes a firing furnace, a reformer, and a hydrogen separator in addition to the fuel cell. The hydrogen separator is required when a phosphoric acid fuel cell or a solid polymer fuel cell that requires high-purity hydrogen is used as the fuel cell, and is a molten carbonate fuel cell. Alternatively, it can be omitted when a solid oxide fuel cell is employed.

  The firing furnace has a firing furnace main body and combustion means, burns fuel containing methane by the combustion means to generate combustion gas, and fires the object to be fired carried into the firing furnace main body with the combustion gas. The product can be obtained. The reformer is filled with a methane reforming catalyst. The reforming raw material consisting of a fuel containing methane and water vapor (not shown) is added to the methane reforming catalyst, and the exhaust heat generated by the combustion of the firing furnace is removed. Utilizing and contacting with heating, these reactions are caused to produce a reformed gas composed of hydrogen and carbon dioxide. The hydrogen separator receives the reformed gas, selectively separates the hydrogen therein, and separates it into a fuel containing hydrogen as a main component and a residual gas containing carbon dioxide.

  The fuel cell receives high-purity hydrogen obtained in the hydrogen separator as fuel, and generates electric power and generates electric energy while being operated by the operation method of the fuel cell according to the present invention. As a result of the fuel cell being operated by the fuel cell operation method according to the present invention, more unreacted hydrogen is generated than before, and this is sent to the firing furnace together with the residual gas generated in the hydrogen separator, Used as fuel for combustion means.

  That is, in the fuel cell power generation system according to the present invention, unreacted hydrogen generated as a result of operating the fuel cell by the fuel cell operation method according to the present invention is effectively utilized together with the residual gas generated in the hydrogen separator, Does not increase the environmental load. In addition, the reformed gas is generated using the exhaust heat generated by the combustion of the firing furnace, and further hydrogen is generated. Therefore, the thermal energy of the combustion gas generated in the firing furnace is effectively used, which increases the environmental load. Instead, it is converted into high-value electric energy.

  The fuel cell operating method according to the present invention is suitable as a method for operating all fuel cells including automobile fuel cells, household fuel cells, factory fuel cells, and the like.

It is a schematic block diagram of the fuel cell for demonstrating the technical idea common to the operating method of the 1st-6th fuel cell which concerns on this invention. It is a schematic block diagram of the fuel cell for demonstrating the operating method of the conventional fuel cell. 1 is a schematic configuration diagram showing an embodiment of a fuel cell power generation system according to the present invention. 1 is a schematic configuration diagram showing an embodiment of a first fuel cell power generator according to the present invention. It is a schematic block diagram which shows one Embodiment of the 2nd fuel cell electric power generating apparatus which concerns on this invention. It is a schematic block diagram which shows one Embodiment of the 3rd fuel cell electric power generating apparatus which concerns on this invention. It is a schematic block diagram which shows one Embodiment of the 4th fuel cell electric power generating apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydrogen, 2 ... Oxygen, 3 ... Unreacted hydrogen, 4 ... Water, 11 ... Fuel flow meter, 12 ... Hydrogen concentration meter, 13 ... Controller, 14 ... Control valve, 15 ... Arithmetic unit, 21 ... Unused fuel Flow meter, 22 ... hydrogen concentration meter, 23 ... controller, 24 ... controller, 25 ... controller, 26 ... arithmetic device, 27 ... arithmetic device, 31, 32, 33 ... thermometer, 34, 35, 36 ... voltage 40 ... Fuel cell, 41 ... Electrolyte, 42 ... Fuel electrode, 43 ... Air electrode, 45 ... Arithmetic unit, 50 ... Fuel cell, 51 ... Electrolyte, 52 ... Fuel electrode, 53 ... Air electrode, 60 ... Fuel cell, 70: Fuel cell, 80: Module battery.

Claims (14)

A method of operating a fuel cell in which a plurality of unit cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked Because
A method of operating a fuel cell, wherein the number of moles of oxygen contained in air supplied to the air electrode is controlled to be ½ or less of the number of moles of hydrogen contained in fuel supplied to the fuel electrode. . A method of operating a fuel cell in which a plurality of unit cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked Because
A method for operating a fuel cell, wherein the number of moles of oxygen contained in the air supplied to the air electrode is controlled so that the number of moles of unreacted hydrogen contained in the fuel discharged from the fuel electrode becomes a certain value or more. Between the fuel electrode supplied with fuel containing hydrogen as a main component and the air electrode supplied with air as an oxidant, a plurality of unit cells interposing an electrolyte constitute a module battery, A method of operating a fuel cell configured by connecting a plurality of the module cells,
A method of operating a fuel cell, wherein the temperature of the plurality of module cells is individually measured, and the number of moles of oxygen contained in the air supplied to the air electrode is controlled so that the temperature difference between them is less than a certain value. . A plurality of unit cells having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant constitute a module battery, A method of operating a fuel cell configured by connecting a plurality of module cells,
A method of operating a fuel cell, wherein the voltage of the plurality of module cells is individually measured, and the number of moles of oxygen contained in the air supplied to the air electrode is controlled so that the voltage difference between them is less than a certain value. . A method of operating a fuel cell in which a plurality of unit cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked Because
A method of operating a fuel cell, wherein the temperature of the unit cells is individually measured, and the number of moles of oxygen contained in the air supplied to the air electrode is controlled so that the temperature difference between them is below a certain level. A method of operating a fuel cell in which a plurality of unit cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked Because
A method for operating a fuel cell, wherein the voltage of the unit cell is individually measured, and the number of moles of oxygen contained in the air supplied to the air electrode is controlled so that the voltage difference between them is less than a certain value. A fuel cell in which a plurality of unit cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked;
Supply hydrogen amount measurement means for measuring the number of moles of hydrogen contained in the fuel supplied to the fuel electrode; supply oxygen amount control means for controlling the number of moles of oxygen contained in the air supplied to the air electrode; A fuel cell power generator comprising: A fuel cell in which a plurality of unit cells each having an electrolyte interposed between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant are stacked;
Exhaust hydrogen amount measuring means for measuring the number of moles of unreacted hydrogen contained in the fuel discharged from the fuel electrode, and supply oxygen amount control for controlling the number of moles of oxygen contained in the air supplied to the air electrode And a fuel cell power generator. Between the fuel electrode supplied with fuel containing hydrogen as a main component and the air electrode supplied with air as an oxidant, a plurality of unit cells interposing an electrolyte constitute a module battery, A fuel cell configured by connecting a plurality of the module cells; and
Fuel cell power generation comprising temperature difference measuring means for measuring temperature differences between the plurality of module batteries, and supply oxygen amount control means for controlling the number of moles of oxygen contained in the air supplied to the air electrode apparatus. Between the fuel electrode supplied with fuel containing hydrogen as a main component and the air electrode supplied with air as an oxidant, a plurality of unit cells interposing an electrolyte constitute a module battery, A fuel cell configured by connecting a plurality of the module cells; and
A fuel cell power generation comprising: a voltage difference measuring means for measuring a voltage difference between the plurality of module batteries; and a supply oxygen amount control means for controlling the number of moles of oxygen contained in the air supplied to the air electrode. apparatus. A fuel cell in which a plurality of cells each having an electrolyte interposed are connected between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant;
A fuel cell power generator comprising: a temperature difference measuring unit that measures a temperature difference between the unit cells; and a supply oxygen amount control unit that controls the number of moles of oxygen contained in the air supplied to the air electrode. A fuel cell in which a plurality of cells each having an electrolyte interposed are connected between a fuel electrode supplied with a fuel containing hydrogen as a main component and an air electrode supplied with air as an oxidant;
A fuel cell power generator comprising: a voltage difference measuring unit that measures a voltage difference between the unit cells; and a supply oxygen amount control unit that controls the number of moles of oxygen contained in the air supplied to the air electrode. A firing furnace comprising: combustion means for burning a fuel containing methane to generate combustion gas; and a firing furnace body for firing a body to be fired carried into the interior by the combustion gas;
The methane reforming catalyst is filled inside, and by contacting the methane reforming catalyst while heating the reforming raw material composed of the fuel containing methane and the steam that has flowed into the methane reforming catalyst, A reformer that reacts methane with the water vapor to generate a reformed gas composed of hydrogen and carbon dioxide;
A fuel cell power generator according to any one of claims 7 to 12, and
Using the exhaust heat of the combustion gas generated in the firing furnace body, the reformer generates the reformed gas containing the hydrogen, and uses the reformed gas as fuel for the fuel cell. By generating electric power and burning unreacted reformed gas discharged from the fuel cell as fuel for the combustion means, the reformed gas containing hydrogen can be used effectively, and the thermal energy of the combustion gas can be increased. A fuel cell power generation system that converts part of it into electrical energy. A hydrogen separator that selectively separates the hydrogen in the reformed gas produced by the reformer and separates it into a fuel containing hydrogen as a main component and a residual gas containing carbon dioxide; ,
The reformed gas containing the hydrogen generated in the reformer is separated into hydrogen and carbon dioxide by the hydrogen separator, and the hydrogen is used as fuel for the fuel cell instead of the reformed gas. In addition, the unreacted hydrogen discharged from the fuel cell is combusted as fuel for the combustion means, thereby effectively using hydrogen and converting a part of the thermal energy of the combustion gas into electrical energy. The fuel cell power generation system according to claim 13 to be converted.

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