JP6529945B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system.

In a fuel cell system, as a configuration for improving energy utilization efficiency, a single fuel cell stack is used, and a circulating system in which unreacted fuel gas discharged from the fuel cell stack is circulated and reused, or fuel There is known a multistage system in which a plurality of cell stacks are provided and unreacted fuel gas in used fuel gas discharged from the fuel cell stack at the front stage is reused in the fuel cell stack at the rear stage. In either configuration, if steam and carbon dioxide (CO ₂ ) contained in the used fuel gas can be removed, the concentration of hydrogen and carbon monoxide contributing to the reaction is increased to supply the fuel gas to be reused. Performance of the fuel cell stack can be expected.

  In relation to the above, Patent Document 1 discloses that, in a fuel processing process of a solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell), water vapor is separated from a used fuel gas discharged from a fuel cell stack by a separation membrane. Technology has been disclosed to recycle it as recycled fuel gas. Patent Document 1 shows an example in which air is introduced to the permeation side to reduce the partial pressure of water vapor on the permeation side, whereby the permeation of water vapor in the separation membrane is promoted.

US Patent Publication 2013/0108936

  By the way, although the above-mentioned separation membrane is used for the purpose of permeation of water vapor and the like, leak to the permeation side may occur even for unintended gas. The gas that leaks to the permeation side also includes combustible gases such as hydrogen and carbon monoxide, and it is necessary to treat appropriately. In addition, when the separation membrane is damaged, a large amount of combustible gas may flow out to the permeation side.

  The present invention has been made in consideration of the above facts, and when sweep gas is supplied to the permeate side of the separation membrane used when generating regeneration gas from the anode off gas, sweep gas discharged from the permeate side is used. The purpose is to obtain a fuel cell system that can be properly processed.

The fuel cell system according to the invention of claim 1 generates electric power by the fuel gas supplied to the fuel electrode and the air supplied to the air electrode, and the anode off gas is discharged from the fuel electrode and the cathode off gas from the air electrode. The fuel cell from which the fuel is discharged, the inflow part into which the anode off gas flows, and the permeation part separated from the inflow part by a separation membrane that separates at least one of carbon dioxide and water vapor from the anode off gas A separator for delivering regenerated fuel gas from which the concentration of at least one of carbon dioxide and water vapor is reduced from the anode off gas, an air supplier for supplying air to the permeate as the sweep gas, and exhaust from the permeate the transmissive portion emissions directly or indirectly permeate gas combustion introducing passageway for introducing the combustible gas into the combustion section for combusting the said component Provided upstream of the parts, and a, a first heat exchanger for exchanging heat between the air from the anode off gas and the air supply unit.

The fuel cell system according to claim 1 has a separation unit. The separation unit includes a separation membrane that separates at least one of carbon dioxide and water vapor from the anode off gas, and has an inflow portion and a permeation portion separated from each other by the separation membrane. Air as the sweep gas flows into the permeation section. Thereby, the partial pressure of at least one of carbon dioxide and water vapor in the permeation part is reduced as compared with the case where there is no passage of air. Meanwhile, the anode off gas flows into the inflow portion. At least one of carbon dioxide and water vapor contained in the anode off gas that has flowed into the inflow portion permeates the separation membrane and flows into the permeation portion. As a result, the concentration of at least one of carbon dioxide and water vapor in the anode off gas is reduced, and is sent out from the inflow portion as regenerated fuel gas. The regenerated fuel gas can be used again for power generation of the fuel cell.

Then, the permeated part exhaust gas discharged from the permeated part is introduced into the combustor directly or indirectly through the permeated gas combustion introduction path. Therefore, even if combustible gas such as hydrogen and carbon monoxide leaks to the permeation part through the separation membrane from the inflow part of the separation part, these combustible gases are finally subjected to combustion in the combustion part . Thereby, the permeated part exhaust gas can be properly treated.

The fuel cell system according to the invention of claim 11 , wherein the permeation gas combustion introduction passage discharges from the air electrode an oxidation gas introduction passage for introducing the permeation portion exhaust gas discharged from the permeation portion into the air electrode. And a cathode off combustion introduction pipe for introducing the cathode off gas into the combustor.

In the fuel cell system according to claim 11, the transmission part exhaust gas discharged from the transmission part is introduced to the air electrode by the oxidizing gas introduction passage, and the cathode off gas discharged from the air electrode is combusted by the cathode off combustion introduction pipe Introduced into the According to the above configuration, the introduction of air to the air electrode and the introduction of air to the separation unit can be performed using the same air supply unit (blower or the like), and the fuel cell system can be simplified. it can.

The fuel cell system according to the invention as set forth in claim 1 is provided with a first heat exchange unit provided on the upstream side of the separation unit and performing heat exchange between the anode off gas and the air from the air supply unit. ing.

According to the fuel cell system according to claim 1, in the first heat exchanger performs heat exchange between the anode exhaust gas and the air flowing into the separation unit, the anode off gas and the air after heat exchange inlet of the separation unit And flow into the permeation section. Therefore, for example, by adjusting the flow rate of air and adjusting the temperature, both the anode off gas and the air flowing into the separation part can be easily set to an appropriate temperature. As described above, by maintaining the separation part at an appropriate temperature to exhibit the performance of the separation membrane, it is possible to separate a large amount of at least one of carbon dioxide and water vapor from the anode off gas. As a result, power can be efficiently generated by the fuel cell stack that reuses the anode off gas, and the performance of the fuel cell system can be improved.

The fuel cell system according to the invention of claim 2 is characterized in that the first heat exchange section performs heat exchange between the anode off gas and the air from the air supply section in a cocurrent flow type.

In the fuel cell system according to claim 2 , in the first heat exchange unit, the anode off gas and the air from the air supply unit are heat-exchanged in a cocurrent (parallel current) type, so the anode off gas sent to the separation unit And the temperature of the air can be relatively easily made the same.

The fuel cell system according to the invention of claim 3 is provided with an air temperature raising portion provided between the air supplying portion and the first heat exchanging portion to raise the temperature of the air from the air supplying portion; And a control unit that controls the temperature of the air flowing out of the air heating unit according to the temperature of the separation unit.

In the fuel cell system according to the third aspect , the air flowing into the first heat exchange unit is heated by the air temperature raising unit according to the temperature of the separation unit. Therefore, the adjustment range of the flow rate of the air flowing into the first heat exchange unit can be reduced, and the separation unit can be maintained at an appropriate temperature. Thereby, the air to be introduced into the permeation part can be secured, and the partial pressure of at least one of carbon dioxide and water vapor in the permeation part can be reduced.

The fuel cell system according to the invention of claim 4 is characterized in that the flow rate of air flowing into the first heat exchange unit from the air supply unit is constant.

According to the fuel cell system of the fourth aspect , the temperature of the separation unit can be made appropriate only by adjusting the temperature of the air in the air heating unit.

The fuel cell system according to the invention of claim 5 includes a control unit that controls the flow rate of air flowing into the first heat exchange unit in accordance with the temperature of the separation unit.

In the fuel cell system according to claim 5 , the flow rate of air flowing into the first heat exchange unit is controlled in accordance with the temperature of the separation unit. Therefore, it is possible to easily bring the temperature of the separation unit to an appropriate temperature simply by adjusting the air flow rate.

The fuel cell system according to the invention of claim 6 is a second heat exchange unit which performs heat exchange between the anode off gas flowing upstream of the first heat exchange unit and the regenerated fuel gas. It is further equipped with

According to the fuel cell system of the sixth aspect , the temperature of the anode off gas is lowered in the second heat exchange unit on the upstream side of the first heat exchange unit, so the temperature adjustment range in the first heat exchange unit is reduced. be able to. In addition, since the temperature of the regenerated fuel gas after passing through the separation unit is raised in the second heat exchange unit, the temperature is close to a temperature suitable for reuse, and the power generation efficiency and thermal efficiency of the entire system can be improved. .

In the fuel cell system according to the invention as set forth in claim 12 , the fuel cell supplies a first fuel cell that delivers anode off gas to the inflow portion of the separation unit, and the regenerated fuel gas is supplied to the fuel electrode as the fuel gas. And a second fuel cell.

According to the fuel cell system of claim 12 , the regenerated fuel gas in which the concentration of at least one of carbon dioxide and water vapor is reduced in the separation unit is the fuel electrode of the second fuel cell, with respect to the anode off gas discharged from the fuel cell. It is supplied to and used. Thereby, a multistage fuel cell system can be realized.
In the fuel cell system according to the invention as set forth in claim 13 , the air supply unit further supplies air to the air electrode.
According to the fuel cell system of the present invention, the fuel gas supplied to the fuel electrode and the air supplied to the air electrode generate electric power, and the anode off gas is discharged from the fuel electrode and the air is generated. A fuel cell in which a cathode off gas is discharged from a pole, an inflow portion into which the anode off gas flows, and a permeation portion partitioned from the inflow portion by a separation membrane that separates at least one of carbon dioxide and water vapor from the anode off gas A separation unit for delivering regenerated fuel gas from the anode off gas in which the concentration of at least one of carbon dioxide and water vapor is reduced, an air supply unit for supplying air to the permeation unit as a sweep gas, and the permeation Permeated gas combustion introduction which introduces the permeated part exhaust gas discharged from the unit into the combustion part which burns combustible gas directly or indirectly When having a heat exchanger for exchanging heat between the discharged combustion gas from the combustion section and the discharge permeate section exhaust gas from said transmitting unit, the transmitting unit exhaust gas in the heat exchange section The temperature is raised by heat exchange and is supplied to the air electrode.
The fuel cell system according to the invention as claimed in claims 8 and 10 generates electric power by the fuel gas supplied to the fuel electrode and the air supplied to the air electrode, and the anode off gas is discharged from the fuel electrode and the air is generated. A fuel cell in which a cathode off gas is discharged from a pole, an inflow portion into which the anode off gas flows, and a permeation portion partitioned from the inflow portion by a separation membrane that separates at least one of carbon dioxide and water vapor from the anode off gas A separation unit for delivering regenerated fuel gas from the anode off gas in which the concentration of at least one of carbon dioxide and water vapor is reduced, an air supply unit for supplying air to the permeation unit as a sweep gas, and the permeation Gas is introduced into the combustion unit where the combustible gas is burned directly or indirectly by the permeated gas discharged from the fuel unit. And road, further comprising a blower supplies air to separate the air electrode and the air supply unit.

  According to the fuel cell system of the present invention, when the sweep gas is supplied to the permeation side of the separation membrane used when generating the regeneration gas from the anode off gas, the sweep gas discharged from the permeation side is appropriately treated can do.

It is a schematic block diagram of the fuel cell system concerning a 1st embodiment. It is a schematic block diagram of the fuel cell system concerning the modification of a 1st embodiment. It is a schematic block diagram of the fuel cell system concerning a 2nd embodiment. It is a schematic block diagram of the fuel cell system concerning a 3rd embodiment. It is a schematic block diagram of the fuel cell system concerning a 4th embodiment. It is a schematic block diagram of the fuel cell system concerning the modification of a 4th embodiment. It is a schematic block diagram of the fuel cell system concerning a 5th embodiment. It is a schematic block diagram of the fuel cell system concerning a 6th embodiment. It is a schematic block diagram of the fuel cell system concerning a 7th embodiment. It is a schematic block diagram of the fuel cell system concerning the modification of a 7th embodiment. It is a schematic block diagram of the fuel cell system concerning an 8th embodiment. It is a schematic block diagram of the fuel cell system concerning a 9th embodiment.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

First Embodiment
FIG. 1 shows a fuel cell system 10A according to a first embodiment of the present invention. The fuel cell system 10A mainly includes a vaporizer 12, a reformer 14, a first fuel cell stack 16, a second fuel cell stack 18, an air supply unit 46, a separation unit 20, and a first heat exchange unit 30, A second heat exchange unit 32, a third heat exchange unit 34, a fourth heat exchange unit 36, a combustor 40, a tank 42, and a control unit 44 are provided.

  One end of a source gas pipe P1 is connected to the vaporizer 12, and the other end of the source gas pipe P1 is connected to a gas source (not shown). From the gas source, methane is delivered to the vaporizer 12 by the blower B. A water supply pipe P2 from a tank 42 for storing water is connected to an intermediate portion of the source gas pipe P1. Water (liquid phase) is delivered from the tank 42 to the vaporizer 12 by the pump P. In the vaporizer 12, water is vaporized. For the vaporization, the heat of a combustor 40 described later is used. In the present embodiment, although methane is used as the source gas, it is not particularly limited as long as it is a gas that can be reformed, and hydrocarbon fuel can be used. Examples of hydrocarbon fuels include natural gas, LP gas (liquefied petroleum gas), coal reformed gas, and lower hydrocarbon gas. The lower hydrocarbon gas includes lower hydrocarbons having 4 or less carbon atoms such as methane, ethane, ethylene, propane and butane, and methane used in the present embodiment is preferable. The hydrocarbon fuel may be a mixture of the above-described lower hydrocarbon gas, and the above-described lower hydrocarbon gas may be a gas such as a natural gas, a city gas, or an LP gas.

  Methane and steam are delivered from the vaporizer 12 to the reformer 14 via the pipe P3. The reformer 14 is adjacent to the combustor 40, the first fuel cell stack 16, and the second fuel cell stack 18, and is heated by heat exchange therebetween.

  The reformer 14 reforms methane to generate a fuel gas G1 containing hydrogen and having a temperature of about 600.degree. The reformer 14 is connected to the anode (fuel electrode) 16 A of the first fuel cell stack 16. The fuel gas G1 generated by the reformer 14 is supplied to the anode 16A of the first fuel cell stack 16 via the fuel gas pipe P4.

  The first fuel cell stack 16 is a solid oxide fuel cell stack, and has a plurality of fuel cells stacked. The first fuel cell stack 16 is an example of the fuel cell (first fuel cell) in the present invention, and in the present embodiment, the operating temperature is set to about 650.degree. Each fuel cell has an electrolyte layer, and an anode 16A and a cathode (air electrode) 16B stacked on the front and back surfaces of the electrolyte layer. In FIG. 1, individual anodes and cathodes of a plurality of fuel cells are collectively shown as "anode 16A" and "cathode 16B", respectively.

  The basic configuration of the second fuel cell stack 18 is the same as that of the first fuel cell stack 16, and has an anode 18A corresponding to the anode 16A and a cathode 18B corresponding to the cathode 16B.

An oxidant gas G5 (air) is supplied to the cathode 16B of the first fuel cell stack 16 via an oxidant gas pipe P5 described later. At the cathode 16B, oxygen in the oxidizing gas reacts with electrons to generate oxygen ions, as shown in the following equation (1). The generated oxygen ions pass through the electrolyte layer and reach the anode 16A of the first fuel cell stack 16.

(Air electrode reaction)
^{_{1 / 2O 2 + 2e - →}} O 2- ... (1)

Further, a cathode off gas pipe P6 for guiding the cathode off gas G2 discharged from the cathode 16B to the cathode 18B of the second fuel cell stack 18 is connected to the cathode 16B.

  On the other hand, at the anode 16A of the first fuel cell stack 16, as shown in the following formulas (2) and (3), oxygen ions having passed through the electrolyte layer react with hydrogen and carbon monoxide in the fuel gas, Water (water vapor) and carbon dioxide and electrons are generated. Electrons generated at the anode 16A move from the anode 16A through the external circuit to the cathode 16B, whereby power is generated in each fuel cell. In addition, each fuel cell generates heat at the time of power generation.

(Anode reaction)
H ₂ + O ^2- → H ₂ O + 2 e ⁻ (2)
_{^{CO + O 2- → CO 2 +}} 2e - ... (3)

  One end of an anode off gas pipe P7 is connected to the anode 16A of the first fuel cell stack 16, and the anode off gas G3 is discharged from the anode 16A to the anode off gas pipe P7. The anode off gas G3 contains unreacted hydrogen, unreacted carbon monoxide, carbon dioxide, water vapor and the like.

The fuel cell of the present invention is not limited to a solid oxide fuel cell (SOFC), and is another fuel cell in which at least one of carbon dioxide and hydrogen is contained in the anode off gas. For example, it may be a molten carbonate fuel cell (MCFC).

The other end of the anode off gas pipe P <b> 7 is connected to the separation unit 20 through a second heat exchange unit 32 and a first heat exchange unit 30 described later. The separation unit 20 separates the carbon dioxide and the water vapor from the anode off gas G3 by a separation film 28 described later. The separation unit 20 includes an inflow unit 24 and a transmission unit 26. The inflow portion 24 and the permeation portion 26 are partitioned by the separation membrane 28.

The other end of the air supply pipe P8 is connected to the transmission part 26 of the separation part 20. The air supply unit 46 includes a blower, and one end of an air supply pipe P8 is connected to the air supply unit 46. Air A at normal temperature is delivered from the air supply unit 46, and air A as a sweep gas is supplied from the air supply unit 46 to the transmission unit 26 through the air supply pipe P8. The air supply unit 46 is connected to a control unit 44 described later.

  Here, the separation membrane 28 will be described. In the present embodiment, the separation membrane 28 has a function of transmitting both carbon dioxide and water vapor. In the present embodiment, although one having a function of transmitting both carbon dioxide and water vapor is used, it may have a function of transmitting at least one of carbon dioxide and water vapor. The polymer is not particularly limited as long as it has a function of transmitting both carbon dioxide and water vapor, and examples thereof include organic polymer films, inorganic material films, organic polymer-inorganic material composite films, liquid films and the like. In addition, the separation membrane is preferably a glassy polymer membrane, a rubbery polymer membrane, an ion exchange resin membrane, an alumina membrane, a silica membrane, a carbon membrane, a zeolite membrane, a ceramic membrane, an aqueous amine membrane or an ionic liquid membrane. preferable.

  Examples of separation membranes include organic polymer membranes such as glassy polymer membranes, rubber-like polymer membranes, and ion exchange resin membranes. The material of the organic polymer film is a polyolefin resin such as polyethylene, polypropylene, polybutene or polymethylpentene, a fluorine resin such as polytetrafluoroethylene, polyvinyl fluoride or polyvinylidene fluoride, polystyrene, cellulose acetate, polyurethane or polyacrylonitrile And various organic materials such as polysulfone, polyethersulfone, polyphenylene sulfide, polyimide, polyamide, polyetherimide, polypyrrole, polyphenylene oxide, polyaniline, polyvinyl alcohol, polyacrylic acid and polyethylene glycol. The organic polymer film may be a film composed of one type of organic material, or may be a film composed of two or more types of organic materials.

  The separation membrane may be, for example, polyvinyl alcohol, polyacrylic acid, polyvinyl alcohol-polyacrylate copolymer, an organic polymer having water absorbability such as polyethylene glycol, and the like, and affinity with carbon dioxide, and water solubility. It may be an organic polymer film containing a carbon dioxide carrier exhibiting the property.

  As the carbon dioxide carrier, inorganic materials and organic materials are used. For example, as the inorganic materials, alkali metal salts (preferably alkali metal carbonates), ammonia, ammonium salts and the like can be mentioned, and as the organic materials, for example, Amines, amine salts, polyamines and the like can be mentioned. The carbon dioxide carrier may be contained in an inorganic material film, an organic polymer-inorganic material composite film, a liquid film or the like.

  Examples of the separation membrane include inorganic membrane such as alumina membrane, silica membrane, carbon membrane, zeolite membrane, ceramic membrane, etc. Among them, zeolite membrane is preferable as the inorganic membrane. Examples of the zeolite include A-type, Y-type, T-type, ZSM-5 type, ZSM-35 type and mordenite type. Further, the inorganic material film may be a film composed of one type of inorganic material, or may be a film composed of two or more types of inorganic materials.

  The separation membrane may be an organic polymer-inorganic material composite membrane. The organic polymer-inorganic material composite film is not particularly limited as long as it is a film composed of an organic material and an inorganic material, but, for example, at least one organic material selected from the organic materials described above and the inorganic materials described above It is preferable that it is a composite film comprised from at least 1 sort (s) of inorganic material selected from.

  Examples of separation membranes include liquid membranes such as aqueous amine solutions and ionic liquids. These liquid films may be those obtained by impregnating the above-mentioned organic polymer film, inorganic material film, organic polymer-inorganic material composite film with an aqueous amine solution or an ionic liquid.

  When an aqueous amine film is used as a separation membrane, carbon dioxide in the off gas is chemically adsorbed to the aqueous amine film and then heated to separate carbon dioxide, and carbon dioxide is separated on the permeation side of the aqueous amine film. Moving. Examples of the aqueous amine solution include aminoalcohols such as monoethanolamine.

  When an ionic liquid membrane is used as a separation membrane, carbon dioxide in the off gas is adsorbed to the ionic liquid membrane, and the adsorbed carbon dioxide is separated from the ionic liquid membrane, whereby carbon dioxide is on the permeation side of the ionic liquid membrane. Moving. Here, the ionic liquid is a salt having a relatively low melting point of 150 ° C. or less, and, for example, a cation such as imidazolium ion or pyridinium ion, trifluoromethanesulfonate ion, tetrafluoroborate ion, hexafluoromethane ion And anions such as phosphate ions.

  The thickness of the separation membrane is not particularly limited, but in view of mechanical strength, a range of 10 μm to 3000 μm is usually preferable, more preferably 10 μm to 500 μm, and still more preferably 15 μm to 150 μm. is there.

  The separation membrane may be supported by a porous support. The material of the support includes paper, cellulose, polyester, polyolefin, polyamide, polyimide, polysulfone, polycarbonate, metal, glass, ceramic and the like.

  Further, as a separation membrane, from the viewpoint of exhibiting the function of separating carbon dioxide and water vapor and maintaining durability, the appropriate temperature T0 at the time of use is higher than the dew point in the fuel cell system 10A, and the first fuel cell A temperature lower than the temperature of the anode off gas G3 immediately after being discharged from the anode 16A of the stack 16 is preferably used. For example, assuming that the dew point is 80 ° C. and the maximum use temperature taking into consideration the durability of the separation membrane is 130 ° C., an appropriate temperature T0 described later is set between 80 ° C. and 130 ° C.

As a separation membrane which separates carbon dioxide and water vapor, for example, the membranes described in “Zi Tong et al.,“ Water vapor and CO ₂ transport through amine-containing facilitated transport membranes ”, Reactive & Functional Polymers (2014) may be used. May be

  The concentration of carbon dioxide and water vapor is reduced by separating at least one of carbon dioxide and water vapor in the separation unit 20, and the anode off gas G3 is discharged from the permeation unit 26 as regenerated fuel gas G4. The regenerated fuel gas pipe P9 is connected to the anode 18A of the second fuel cell stack 18, and the regenerated fuel gas G4 is supplied to the anode 18A of the second fuel cell stack 18 through the regenerated fuel gas pipe P9.

  On the other hand, in the transmission part 26 of the separation part 20, the air A supplied from the air supply pipe P8 flows into the transmission part 26 as a sweep gas. As a result, the partial pressure of carbon dioxide and water vapor in the permeable portion 26 decreases, and the carbon dioxide and water vapor easily move to the permeable portion 26 through the separation film 28 from the inflow portion 24. The air A is delivered from the permeation section 26 as a permeation section exhaust gas, together with carbon dioxide, water vapor, and other gases in the anode off gas G3 that has permeated through the separation membrane 28. The transmitted permeated portion exhaust gas is supplied to the cathode 16B as the oxidizing gas G5 containing oxygen through the oxidizing gas pipe P5.

  At the anode 18 A and the cathode 18 B of the second fuel cell stack 18, power generation is performed by the same reaction as the first fuel cell stack 16. The used gases exhausted from the anode 18A and the cathode 18B are delivered to the combustor 40 by the pipe P11 and the cathode off combustion introduction pipe P12, and subjected to incineration in the combustor 40. In the fuel cell system 10A of the present embodiment, a multistage fuel cell in which the anode off gas G3, which is the fuel used in the first fuel cell stack 16, is regenerated and reused in the second fuel cell stack 18 as fuel gas. It is a system.

  From the combustor 40, the combustion exhaust gas G6 is delivered. The combustion exhaust gas G6 flows in the combustion exhaust gas pipe P10, and flows into the tank 42 through the third heat exchange unit 34, the fourth heat exchange unit 36, and the vaporizer 12.

  Next, heat exchange in the fuel cell system 10A will be described. The fuel cell system 10A includes a first heat exchange unit 30, a second heat exchange unit 32, a third heat exchange unit 34, and a fourth heat exchange unit 36.

  The first heat exchange unit 30 is disposed downstream of the anode 16A of the first fuel cell stack 16 upstream of the separation unit 20 (inflow unit 24) (with respect to the anode off gas pipe P7) and downstream of the air supply unit 46. It is provided on the upstream side (about the air supply pipe P8) of the separation unit 20 (transmission unit 26). In the first heat exchange unit 30, heat exchange is performed between the anode off gas G3 flowing through the anode off gas pipe P7 and the air A flowing through the air supply pipe P8. The heat exchange is preferably performed in parallel. By performing the heat exchange in parallel, the temperatures of the anode off gas G3 and the air A delivered to the separation unit 20 can be relatively easily made the same temperature. The temperature of the anode off gas G3 is lower than that at the time of delivery from the anode 16 due to heat exchange in the second heat exchange unit 32 described later after being delivered from the anode 16A.

  Here, at a temperature suitable for separating at least one of carbon dioxide and water vapor from the anode off gas G by the separation membrane 28, and at a temperature at which the durability of the separation membrane 28 can be maintained, and an appropriate temperature T0 higher than the dew point Then, it is preferable that the temperature of the air A and the anode off gas G3 flowing from the first heat exchange unit 30 into the separation unit 20 be close to the appropriate temperature T0. Therefore, the control unit 44 controls the flow rate of the air A sent from the air supply unit 46 so that the air A and the anode off gas G3 flowing into the separation unit 20 from the first heat exchange unit 30 approach the appropriate temperature T0. . The appropriate temperature T0 is appropriately set according to the material of the separation membrane 28 and the like. As described above, for example, assuming that the dew point is 80 ° C. and the maximum use temperature taking into consideration the durability of the separation film 28 is 130 ° C., the appropriate temperature T0 is set between 80 ° C. and 130 ° C.

  The separation unit 20 is provided with a temperature sensor SS that measures the temperature T of the separation unit 20. The control unit 44 controls the flow rate of the air A delivered from the air supply unit 46 based on the temperature of the separation unit 20 measured by the temperature sensor SS. Specifically, when the temperature T is lower than the appropriate temperature T0, the flow rate of the air A delivered from the air supply unit 46 is decreased, and when the temperature T is higher than the appropriate temperature T0, delivery is performed from the air supply unit 46 Increase the flow rate of air A. During operation of the fuel cell system 10A, the temperature of the separation unit 20 is appropriately controlled by feedback controlling the flow rate of the air A delivered from the air supply unit 46 based on the temperature T constantly or intermittently by the control unit 44. Alternatively, the temperature can be maintained close to the appropriate temperature T0. The temperature T of the separation unit 20 may be the temperature inside the separation unit 20 or may be the temperature of another portion of the separation unit 20 to which the separation membrane 28 is affected.

  The second heat exchange unit 32 is located downstream of the anode 16A of the first fuel cell stack 16 on the upstream side of the first heat exchange unit 30 (for the anode off gas pipe P7) and downstream of the separation unit 20 (inflow unit 26). It is provided on the upstream side of the anode 18A of the second fuel cell stack 18 (about the regenerated fuel gas pipe P9) on the side. In the second heat exchange unit 32, heat exchange is performed between the anode off gas G3 flowing through the anode off gas pipe P7 and the regenerated fuel gas G4 flowing through the regenerated fuel gas pipe P9. The anode off gas G3 is normally at a high temperature of about 650 ° C., and the regenerated fuel gas G4 flowing through the regenerated fuel gas pipe P9 has a temperature close to the appropriate temperature T0 of the separation unit 20. In the second heat exchange unit 32, the temperature of the anode off gas G3 is decreased, and the temperature of the regenerated fuel gas G4 is increased.

  The third heat exchange unit 34 is vaporized downstream of the separation unit 20 (inflow unit 26) upstream of the cathode 16B of the first fuel cell stack 16 (with respect to the oxidizing gas pipe P5) and downstream of the combustor 40. It is provided on the upstream side of the vessel 12 (about the flue gas pipe P10). In the third heat exchange unit 34, heat exchange is performed between the oxidizing gas G5 flowing through the oxidizing gas pipe P5 and the combustion exhaust gas G6 flowing through the combustion exhaust pipe P10. The oxidizing gas G5 flowing through the oxidizing gas pipe P5 has a temperature close to the appropriate temperature T0 of the separation unit 20. In the third heat exchange unit 34, the oxidation gas G5 supplied to the cathode 16B is heated by the combustion exhaust gas G6.

  The fourth heat exchange unit 36 is downstream of the separation unit 20, upstream of the second heat exchange unit 32 (about the regenerated fuel gas pipe P9), and upstream of the vaporizer 12 downstream of the third heat exchange unit 34. Heat exchange is performed between the regenerated fuel gas G4 provided on the side (about the combustion exhaust gas pipe P10) and flowing through the regeneration fuel gas pipe P9 and the combustion exhaust gas G6 flowing through the combustion exhaust gas pipe P10. The regenerated fuel gas G4 flowing through the regenerated fuel gas pipe P9 has a temperature close to the appropriate temperature T0 of the separation unit 20, and is heated by the combustion exhaust gas G6 in the fourth heat exchange unit 36.

  Next, the operation of the fuel cell system 10A of the present embodiment will be described.

  In the fuel cell system 10A, methane which is fuel from a gas source and water from a tank 42 are supplied to the vaporizer 12. In the vaporizer 12, the supplied methane and water are mixed, and heat is obtained by obtaining heat from the flue gas G6 flowing through the flue gas pipe P10, and the water is vaporized to be steam.

  Methane and steam are delivered from the vaporizer 12 to the reformer 14 via the pipe P3. In the reformer 14, a fuel gas G1 of about 600 ° C. containing hydrogen is generated by the reforming reaction. The fuel gas G1 is supplied to the anode 16A of the first fuel cell stack 16 via the fuel gas pipe P4.

In the cathode 16B of the first fuel cell stack 16, the permeated part exhaust gas (mixed gas of air A, carbon dioxide and water vapor) discharged from the permeated part 26 of the separating part 20 is mixed with the oxidizing gas pipe P5 as the oxidizing gas G5. Supplied through. Thereby, in the first fuel cell stack 16, power generation is performed by the aforementioned reaction. The reaction causes the first fuel cell stack 16 to generate heat, and power generation is performed at a temperature of about 650.degree. With the power generation, the anode off gas G3 is discharged from the anode 16A of the fuel cell stack 16. The cathode off gas G2 is discharged from the cathode 16B, and the cathode off gas G2 is supplied to the cathode 18B of the second fuel cell stack 18 through the cathode off gas pipe P6.

  The anode off gas G3 discharged from the anode 16A is led to the anode off gas pipe P7, flows through the second heat exchange unit 32 and the first heat exchange unit 30, and flows into the inflow unit 24 of the separation unit 20. In the second heat exchange unit 32, the temperature of the anode off gas G3 drops to some extent from about 650 ° C. (a decrease of about 80 ° C. to 140 ° C.), and in the first heat exchange unit 30, the temperature of the anode off gas G3 is It is lowered to a temperature close to the appropriate temperature T0.

  On the other hand, air A whose flow rate is controlled by feedback control of temperature T of separation unit 20 by control unit 44 is sent from air supply unit 46 to transmission unit 26 of separation unit 20 via first heat exchange unit 30. Ru. In the first heat exchange unit 30, the temperature of the air A becomes a temperature close to the appropriate temperature T0, that is, substantially the same temperature as the anode off gas G3 after heat exchange is performed in the first heat exchange unit 30.

  The anode off gas G3 flows into the inflow portion 24 of the separation portion 20 through heat exchange in the second heat exchange portion 32 and the first heat exchange portion 30, and at least one of carbon dioxide and water vapor permeates the separation membrane 28. And are separated by moving toward the transmitting portion 26 side. Regenerated fuel gas G4 is delivered from the inflow portion 24, passes through the fourth heat exchange portion 36 and the second heat exchange portion 32, and is heated to about 600 ° C., and the regenerated fuel gas pipe P9 is used to It is supplied to the anode 18A.

  In the second fuel cell stack 18, power generation is performed by the above-described reaction. By the reaction, the second fuel cell stack 18 generates heat, and power generation is performed at a temperature of about 650.degree. The spent gas at the anode 18A and the cathode 18B is delivered to the combustor 40 by the pipe P11 and the cathode off combustion inlet pipe P12, respectively, and subjected to incineration at the combustor 40.

  The combustion exhaust gas G6 from the combustor 40 passes through the third heat exchange unit 34, the fourth heat exchange unit 36, and the vaporizer 12 and is delivered to the tank 42 by the combustion exhaust gas pipe P10. The water vapor contained in the combustion exhaust gas G6 is cooled in the path from the vaporizer 12 to the tank 42 and in the tank 42, and is condensed and stored in the tank 42. The other combustion exhaust gas is discharged from the tank 42.

On the other hand, the air A as the sweep gas flowing into the permeation portion 26 is the permeation portion 26 together with the carbon dioxide, the water vapor which permeated through the separation membrane 28, the water vapor, and other gases in the anode off gas G 3 which permeated through the separation membrane 28. It is sent from The permeated portion exhaust gas thus delivered passes through the fourth heat exchange portion 36 and the third heat exchange portion 34, and is supplied as the oxidation gas G5 to the cathode 16B by the oxidation gas pipe P5.

In the fuel cell system 10A of the present embodiment, since the air A as the sweep gas is supplied to the permeation side (permeation unit 26) of the separation membrane 28, the partial pressure of carbon dioxide and water vapor in the permeation unit 26 is reduced. As a result, at least one of carbon dioxide and water vapor contained in the anode off gas G3 flowing into the inflow portion 24 can be separated by passing through the separation membrane 28 more.

Further, since the anode off gas G3 and the air A heat-exchanged in the first heat exchange unit 30 so as to approach the appropriate temperature T0 are flowed into the separation unit 20, the separation unit 20 is maintained at the appropriate temperature T0 and the separation film 28 performance can be exhibited. As a result, at least one of carbon dioxide and water vapor can be separated from the anode off gas G3 in a large amount, and the durability of the separation membrane 28 can be maintained. Then, since the regenerated fuel gas G4 with reduced carbon dioxide and water vapor is supplied to the second fuel cell stack 18 that reuses the anode off gas G3, power can be efficiently generated, and the performance of the fuel cell system 10A Can be improved.

Further, heat exchange in the first heat exchange unit 30 is performed between the air A, which is a gas supplied to the separation unit 20, and the anode off gas G3, and adjustment to the appropriate temperature T0 is performed by setting the flow rate of the air A to Since the control is performed, the temperature of the separation unit 20 can be easily adjusted.

In the present embodiment, the temperature of the separation unit 20 is fed back to adjust the flow rate of the air A delivered from the air supply unit 46, but the air A delivered from the first heat exchange unit 30 and the anode off gas G3 The temperature may be measured, and this temperature may be fed back to adjust the flow rate of the air A delivered from the air supply unit 46.

Further, in the present embodiment, the temperature of the anode off gas G3 is decreased in the second heat exchange unit 32 on the upstream side of the first heat exchange unit 30, so that the temperature adjustment width in the first heat exchange unit 30 can be reduced. it can. In addition, since the temperature of the regenerated fuel gas G4 after passing through the separation unit 20 is raised by the second heat exchange unit 32, the temperature is close to a temperature suitable for power generation, and the power generation efficiency and thermal efficiency of the entire fuel cell system 10A are improved. it can.

Further, in the present embodiment, after the permeated part exhaust gas discharged from the permeated part 26 of the separation part 20 is introduced to the cathode 16B and used for power generation, it is introduced to the cathode 18B of the second fuel cell stack 18 to generate electricity. And then delivered to the combustor 40 for combustion. It is considered that hydrogen, carbon monoxide, and other combustible substances are contained in the permeated part exhaust gas due to leak or the like from the anode off gas G3 in the separation membrane 28. According to the fuel cell system 10A of the present embodiment, hydrogen, carbon monoxide and other combustible substances contained in the exhaust gas of the permeation section can be discharged out of the fuel cell system 10A after being burned. The safety of the fuel cell system 10A can be improved.

In the present embodiment, the permeated part exhaust gas discharged from the permeated part 26 is introduced into the cathode 16 B, but the permeated part exhaust gas may be introduced directly into the combustor 40. In this case, as shown in FIG. 2, a permeable portion discharge pipe P13 for delivering the exhaust gas from the permeable portion 26 to the combustor 40 is provided, and air is introduced to the cathode 16B of the first fuel cell stack 16. A blower 54 may be separately prepared.

Further, in the present embodiment, since the transmission part exhaust gas discharged from the transmission part 26 of the separation part 20 is introduced into the cathode 16B of the first fuel cell stack 16, the introduction of air into the cathode 16B The introduction of air to the heat exchange unit 30 can be performed using the same blower, and the fuel cell system 10A can have a simple configuration.

Second Embodiment
Next, a second embodiment of the present invention will be described. The same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 3 shows a fuel cell system 10B according to a second embodiment of the present invention. The fuel cell system 10B is different from the fuel cell system 10A described in the first embodiment in that the temperature of the air delivered from the air supply unit 46 is raised to the first heat exchange unit 30. ing. Further, the flow rate of the air A delivered from the air supply unit 46 is constant, and the temperature of the air and the anode off gas G3 supplied to the separation unit 20 at the flow rate of the air A-1 passing through the valve 48 is adjusted. It is different.

  The air supply pipe P8 connected to the air supply unit 46 is branched into an air adjusting pipe P8-1 and an air temperature raising pipe P8-2 at a branch portion B1, and merged at a merging portion B2. The merging portion B2 is provided upstream of the first heat exchanging portion 30.

  A valve 48 is provided in the air adjusting pipe P8-1. The valve 48 is connected to the control unit 44. The air heating pipe P8-2 is introduced to the fifth heat exchange unit 38. The flue gas pipe P10 on the downstream side of the fourth heat exchanger 36 is introduced to the fifth heat exchanger 38, and the air A-2 passing through the air temperature raising pipe P8-2 is a flue gas pipe P10. The temperature is raised by heat exchange with the flowing combustion exhaust gas G6. An air temperature raising portion is formed by the air adjusting pipe P8-1, the valve 48, the fourth heat exchanging portion 36, and the air temperature raising pipe P8-2.

The control unit 44 controls the flow rate of the air A-1 passing through the valve 48 so that the air A and the anode off gas G3 flowing from the first heat exchange unit 30 into the separation unit 20 approach the appropriate temperature T0. The said control is performed by adjusting the flow volume of air A-1 which passes valve | bulb 48 based on the temperature of the isolation | separation part 20 measured by temperature sensor SS. Specifically, when the temperature T of the separation unit 20 is lower than the appropriate temperature T0, the opening degree of the valve 48 is decreased to decrease the flow rate of the air A-1 passing through the valve 48, and the temperature T becomes the appropriate temperature T0. If higher, the opening degree of the valve 48 is increased to increase the flow rate of the air A-1 passing through the valve 48. During the operation of the fuel cell system 10B, the temperature of the separation unit 20 is controlled to the appropriate temperature T0 by performing feedback control of the flow rate of the air A-1 passing through the valve 48 based on the temperature T constantly or intermittently by the control unit 44. It is possible to maintain the temperature close to the appropriate temperature T0.

  According to the present embodiment, the heat exchange in the first heat exchange unit 30 is performed so that the separation unit 20 has the appropriate temperature T0 while maintaining the flow rate of the air A sent from the air supply unit 46 constant. it can. By maintaining the flow rate of the air A sent from the air supply unit 46 constant, the flow rate of the air A supplied to the transmission unit 26 can be secured.

In addition, the fuel cell system 10B can also achieve the same effects as those of the other first embodiment.

Third Embodiment
Next, a third embodiment of the present invention will be described. The same parts as those in the first and second embodiments will be assigned the same reference numerals and explanation thereof will be omitted.

  FIG. 4 shows a fuel cell system 10C according to a third embodiment of the present invention. The fuel cell system 10C adjusts both the flow rate of the air A delivered from the air supply unit 46 and the flow rate of the air A-1 passing through the valve 48 in comparison with the fuel cell system 10B described in the second embodiment. The point which controls the isolation | separation part 20 to the temperature close | similar to appropriate temperature T0 differs by carrying out.

The control unit 44 is connected to the air supply unit 46 and the valve 48. The control unit 44 passes the air A delivered from the air supply unit 46 and the valve 48 so that the air A and the anode off gas G3 introduced from the first heat exchange unit 30 into the separation unit 20 approach the appropriate temperature T0. Control the flow rate of air A-1. Specifically, when the temperature T of the separation unit 20 measured by the temperature sensor SS is lower than the appropriate temperature T0, the output of the blower of the air supply unit 46 is reduced and the opening degree of the valve 48 is reduced. The flow rate of the air A delivered from the air supply unit 46 and the flow rate of the air A-1 passing through the valve 48 are reduced. On the other hand, when the temperature T is higher than the appropriate temperature T0, the flow rate of the air A delivered from the air supply unit 46 by increasing the output of the blower of the air supply unit 46 and increasing the opening degree of the valve 48 The flow rate of air A-1 passing through 48 is increased. During operation of the fuel cell system 10C, the flow rate of the air A delivered from the air supply unit 46 and the air A-1 passing through the valve 48 constantly or intermittently by the control unit 44 based on the temperature T of the separation unit 20. The temperature of the separation unit 20 can be maintained at a suitable temperature T0 or a temperature close to the proper temperature T0 by feedback control of the flow rate of

  According to the present embodiment, by adjusting both the flow rate of the air A delivered from the air supply unit 46 and the flow rate of the air A-1 passing through the valve 48, the separation unit 20 has the appropriate temperature T0. 1 Heat exchange in the heat exchange unit 30 is performed. Therefore, temperature control of separation part 20 can be performed more flexibly.

In addition, the fuel cell system 10C can also achieve the same effects as those of the other first and second embodiments.

Fourth Embodiment
Next, a fourth embodiment of the present invention will be described. The same parts as those in the first to third embodiments are given the same reference numerals, and descriptions thereof will be omitted.

  FIG. 5 shows a fuel cell system 10D according to a fourth embodiment of the present invention. The fuel cell system 10D is different from the fuel cell system 10A described in the first embodiment in that the second fuel cell stack 18 is not provided.

  The regenerated fuel gas pipe P <b> 9 connected to the separation unit 20 is branched at a branch unit B <b> 3 provided on the downstream side of the fourth heat exchange unit 36. One branched regenerated fuel gas pipe P9-1 is connected to the pipe P3 via the second heat exchange unit 32. The other branched regenerated fuel gas pipe P9-2 is connected to the combustor 40. In the branch portion B3, the regenerated fuel gas G4 is diverted to the regenerated fuel gas pipe P9-1 and the regenerated fuel gas pipe P9-2. A blower 52 is provided upstream of the second heat exchanger 32 of the regenerated fuel gas pipe P9-1. The blower 52 circulates the regenerated fuel gas G4 in the regenerated fuel gas pipe P9-1 toward the pipe P3.

The regenerated fuel gas G4 introduced to the reformer 14 through the regenerated fuel gas pipe P9-1 is mixed with the fuel gas G1 supplied from the vaporizer 12 and supplied to the anode 16A. The regenerated fuel gas G4 introduced into the combustor 40 through the regenerated fuel gas pipe P9-2 is burned in the combustor 40. The cathode off gas G2 discharged from the cathode 16B is introduced into the combustor 40 via the cathode off gas pipe P6.

  In the fuel cell system 10D of the present embodiment, a fuel cell system of a circulation type in which the anode off-gas G3, which is a spent fuel in the first fuel cell stack 16, is regenerated and reused in the first fuel cell stack 16 again. It has become. Also in the present embodiment, the same effects as in the first embodiment can be obtained.

Also in this embodiment, the permeated portion exhaust gas discharged from the permeated portion 26 may be directly introduced into the combustor 40. In this case, as shown in FIG. 6, a permeable portion discharge pipe P13 for delivering the exhaust gas from the permeable portion 26 to the combustor 40 is provided, and air is introduced to the cathode 16B of the first fuel cell stack 16. A blower 54 may be separately prepared.

Fifth Embodiment
Next, a fifth embodiment of the present invention will be described. The same parts as those in the first to fourth embodiments are denoted by the same reference numerals, and the description will be omitted.

  FIG. 7 shows a fuel cell system 10E according to a fifth embodiment of the present invention. The fuel cell system 10E is different from the fuel cell system 10D described in the fourth embodiment in that the air supplied from the air supply unit 46 is heated as in the second embodiment. That is, the flow rate of the air A delivered from the air supply unit 46 is constant, and the temperature of the air and the anode off gas G3 supplied to the separation unit 20 at the flow rate of the air A-1 passing through the valve 48 is adjusted. It is different.

The air supply pipe P8 connected to the air supply unit 46 is branched into an air adjusting pipe P8-1 and an air temperature raising pipe P8-2 at a branch portion B1, and merged at a merging portion B2. The merging portion B2 is provided upstream of the first heat exchanging portion 30.

  A valve 48 is provided in the air adjusting pipe P8-1. The valve 48 is connected to the control unit 44. The air heating pipe P8-2 is introduced to the fifth heat exchange unit 38. The flue gas pipe P10 on the downstream side of the fourth heat exchanger 36 is introduced to the fifth heat exchanger 38, and the air A-2 passing through the air temperature raising pipe P8-2 is a flue gas pipe P10. The temperature is raised by heat exchange with the flowing combustion exhaust gas G6.

In the control unit 44, as in the second embodiment, the air A-1 passing through the valve 48 so that the air A and the anode off gas G3 flowing from the first heat exchange unit 30 into the separation unit 20 approach the appropriate temperature T0. Control the flow rate of

  According to the present embodiment, the heat exchange in the first heat exchange unit 30 is performed so that the separation unit 20 has the appropriate temperature T0 while maintaining the flow rate of the air A sent from the air supply unit 46 constant. it can. By maintaining the flow rate of the air A sent from the air supply unit 46 constant, the flow rate of the air A supplied to the transmission unit 26 can be secured.

In addition, the fuel cell system 10E can also exhibit the same effects as those of the other first embodiment.

Sixth Embodiment
Next, a sixth embodiment of the present invention will be described. The same parts as those in the first to fifth embodiments are given the same reference numerals, and the description will be omitted.

  A fuel cell system 10F according to a sixth embodiment of the present invention is shown in FIG. Similar to the third embodiment, the fuel cell system 10F is different from the fuel cell system 10E described in the fifth embodiment in the flow rate of the air A delivered from the air supply unit 46 and the air A passing through the valve 48. It is different in that the separation unit 20 is controlled to a temperature close to the appropriate temperature T0 by adjusting both of the flow rate of -1.

The control unit 44 is connected to the air supply unit 46 and the valve 48. In the control unit 44, as in the third embodiment, the air supplied from the air supply unit 46 so that the air A and the anode off gas G3 flowing from the first heat exchange unit 30 into the separation unit 20 approach the appropriate temperature T0. A and the flow rate of air A-1 passing through the valve 48 are controlled.

  According to the present embodiment, by adjusting both the flow rate of the air A delivered from the air supply unit 46 and the flow rate of the air A-1 passing through the valve 48, the separation unit 20 has the appropriate temperature T0. 1 Heat exchange in the heat exchange unit 30 is performed. Therefore, temperature control of separation part 20 can be performed more flexibly.

In addition, the fuel cell system 10F can also exhibit the same effects as those of the other fifth and sixth embodiments.

Seventh Embodiment
Next, a seventh embodiment of the present invention will be described. The same parts as those in the first to sixth embodiments are denoted by the same reference numerals, and the description will be omitted.

  FIG. 9 shows a fuel cell system 10G according to a seventh embodiment of the present invention. The fuel cell system 10G is different from the fuel cell system 10A described in the first embodiment in that a third fuel cell stack 17 is included.

  The basic configuration of the third fuel cell stack 17 is the same as that of the first fuel cell stack 16, and has an anode 17A corresponding to the anode 16A and a cathode 17B corresponding to the cathode 16B. The third fuel cell stack 17 is disposed in parallel with the first fuel cell stack 16 in the fuel cell system 10G. Although the second fuel cell stack 18 and the third fuel cell stack 17 are illustrated separately from the reformer 14 in FIG. 7, the second fuel cell stack 18 and the third fuel cell stack are actually shown. Reference numeral 17 is disposed adjacent to the reformer 14 in the same manner as the first fuel cell stack 16 and heat exchange is performed.

The fuel gas pipe P4 connected to the reformer 14 is branched from the fuel gas pipe P4-2 at a branch portion B4. The fuel gas pipe P4 is connected to the anode 16A, and supplies the fuel gas G1 from the reformer 14 to the anode 16A. The fuel gas pipe P4-2 is connected to the anode 17A, and supplies the fuel gas G1 from the reformer 14 to the anode 17A. An anode off gas pipe P7 is connected to the anode 17A, and the anode off gas pipe P7-2 is joined at an anode off gas pipe P7 and a joining portion B5 on the upstream side of the second heat exchange unit 32. The spent anode off gas G3 is delivered from the anode 17A, and flows into the inflow portion 24 of the separation unit 20 through the anode off gas pipes P7-2 and P7.

  The oxidizing gas pipe P <b> 5-2 branched from the oxidizing gas pipe P <b> 5 from the oxidizing gas pipe P <b> 5 at the branching portion B <b> 6 is connected to the cathode 17 </ b> B downstream of the third heat exchanger 34. The oxidizing gas G5 is supplied to the cathode 17B through the oxidizing gas pipe P5-2. The spent gas exhausted from the cathode 17B is joined with the cathode off gas pipe P6 at the joining portion B7 and introduced into the cathode 18B.

  As described above, by having the third fuel cell stack 17 disposed in parallel with the first fuel cell stack 16, the power generation in the first stage of the fuel cell system 10G is performed by the first fuel cell stack 16 and the third fuel cell system 10G. The fuel cell stack 17 is performed. Then, the anode off gas G3 after being used in the first fuel cell stack 16 and the third fuel cell stack 17 is regenerated into the regenerated fuel gas G4 by the separation unit 20, and the second fuel cell stack 18 in the second stage is regenerated. It can be used for power generation.

  According to the fuel cell system 10G of the present embodiment, the difference between the operation rates of the fuel cell stacks of the first and second stages is reduced, and the power generation efficiency of the fuel cell system 10G18 can be improved.

Also in this embodiment, the permeated portion exhaust gas discharged from the permeated portion 26 may be directly introduced into the combustor 40. In this case, as shown in FIG. 10, a permeable portion discharge pipe P13 for delivering the exhaust gas from the permeable portion 26 to the combustor 40 is provided, and air is introduced to the cathode 16B of the first fuel cell stack 16. A blower 54 may be separately prepared.

Eighth Embodiment
Next, an eighth embodiment of the present invention will be described. The same parts as those in the first to seventh embodiments are denoted by the same reference numerals, and the description will be omitted.

  A fuel cell system 10H according to an eighth embodiment of the present invention is shown in FIG. The fuel cell system 10H is different from the fuel cell system 10G described in the seventh embodiment in that the air supplied from the air supply unit 46 is heated as in the second and fifth embodiments. There is. That is, the flow rate of the air A delivered from the air supply unit 46 is constant, and the temperature of the air and the anode off gas G3 supplied to the separation unit 20 at the flow rate of the air A-1 passing through the valve 48 is adjusted. It is different.

The air supply pipe P8 connected to the air supply unit 46 is branched into an air adjusting pipe P8-1 and an air temperature raising pipe P8-2 at a branch portion B1, and merged at a merging portion B2. The merging portion B2 is provided upstream of the first heat exchanging portion 30.

  A valve 48 is provided in the air adjusting pipe P8-1. The valve 48 is connected to the control unit 44. The air heating pipe P8-2 is introduced to the fifth heat exchange unit 38. The flue gas pipe P10 on the downstream side of the fourth heat exchanger 36 is introduced into the fifth heat exchanger 38, and the air A-2 passing through the air temperature raising pipe P8-2 is the same as the flue gas pipe P10. The temperature is raised by heat exchange.

In the control unit 44, as in the second and fifth embodiments, the air A flowing into the separation unit 20 from the first heat exchange unit 30 and the air A passing through the valve 48 so that the anode off gas G3 approaches the appropriate temperature T0. Control the flow rate of -1.

  According to the present embodiment, the heat exchange in the first heat exchange unit 30 is performed so that the separation unit 20 has the appropriate temperature T0 while maintaining the flow rate of the air A sent from the air supply unit 46 constant. it can. By maintaining the flow rate of the air A sent from the air supply unit 46 constant, the flow rate of the air A supplied to the transmission unit 26 can be secured.

In addition, the fuel cell system 10H can also achieve the same effects as those of the other first embodiment.

Ninth Embodiment
Next, a ninth embodiment of the present invention will be described. The same parts as those in the first to eighth embodiments are denoted by the same reference numerals, and the description will be omitted.

  FIG. 12 shows a fuel cell system 10I according to a ninth embodiment of the present invention. Similar to the third and sixth embodiments, the fuel cell system 10I passes the flow rate of the air A delivered from the air supply unit 46 and the valve 48, as compared with the fuel cell system 10H described in the eighth embodiment. It is different in that the separation unit 20 is controlled to a temperature close to the appropriate temperature T0 by adjusting both of the flow rates of the air A-1.

The control unit 44 is connected to the air supply unit 46 and the valve 48. In the control unit 44, as in the third and sixth embodiments, the air A and the anode off gas G3 flowing from the first heat exchange unit 30 into the separation unit 20 are delivered from the air supply unit 46 so as to approach the appropriate temperature T0. Control the flow rate of air A and air A-1 passing through the valve 48.

  According to the present embodiment, by adjusting both the flow rate of the air A delivered from the air supply unit 46 and the flow rate of the air A-1 passing through the valve 48, the separation unit 20 has the appropriate temperature T0. 1 Heat exchange in the heat exchange unit 30 is performed. Therefore, temperature control of separation part 20 can be performed more flexibly.

The fuel cell system 10I can also achieve the same effects as those of the other seventh and eighth embodiments.

In addition, arrangement | positioning of the 2nd heat exchange part 32-5th heat exchange part 38 in said 1st-9th embodiment is not limited to said arrangement | positioning, You may change suitably. Also, as means for separating carbon dioxide and water vapor from the anode off gas G3, for example, other means such as a water condenser, a water vapor adsorbent, a carbon dioxide absorbent, a carbon dioxide adsorbent, etc. may be used in combination with the separator. .

In the first to ninth embodiments described above, the first heat exchange unit 30 is disposed, but the separation film 28 has a separation function at the operation temperature of the first fuel cell stack 16 (about 650 ° C. in the present embodiment) The first heat exchange unit 30 is unnecessary if it can be

In the first to ninth embodiments described above, the flow rate of the air A allowed to flow out of the air supply unit 46 so that the separation unit 20 approaches the appropriate temperature T0 in the control unit 44 or the air caused to flow into the first heat exchange unit 30 Although the temperature of A was controlled, the control unit 44 is not necessarily required. For example, the flow rate of the air A made to flow out of the air supply unit 46 for the separation unit 20 to approach the appropriate temperature T0 and the temperature of the air A made to flow into the first heat exchange unit 30 are obtained by experiment etc. The components (the air supply unit 46 and the valve 48) may be set so that the flow rate of the air A and the temperature of the air A flowing into the first heat exchange unit 30 are achieved.

Furthermore, the present invention is not limited to the above-described first to ninth embodiments, and is implemented by combining the above-described embodiments by those skilled in the art within the technical concept of the present invention. Further, in the present invention, for example, the installation position, combination, and the like of the heat exchanger are not limited to these embodiments. Moreover, you may use means other than a heat exchanger for heating and cooling of various fluids, such as gas and water.

10A to 10I Fuel cell system 16 first fuel cell stack (fuel cell), 17 third fuel cell stack (fuel cell)
18 2nd fuel cell stack (fuel cell),
16A, 17A, 18A Anode (fuel electrode)
16B, 17B, 18B cathode (air electrode)
Reference Signs List 20 separation unit, 24 inflow unit, 26 transmission unit, 28 separation film 30 first heat exchange unit, 32 second heat exchange unit 46 air supply unit, P8-1 air adjustment pipe, 48 valve, 36 fourth heat exchange unit P8 -2 Air heating tube (air heating unit)
40 combustor, 44 control unit, P5 oxidation gas pipe (permeate gas combustion introduction path)
P6 Cathode off gas pipe (permeate gas combustion introduction path)
P12 Cathode-off combustion introduction pipe (permeate gas combustion introduction path)
P13 Permeate exhaust pipe (permeate gas combustion introduction path)
G3 anode off gas, G4 regenerated fuel gas

Claims (13)

A fuel cell which generates electricity by a fuel gas supplied to the fuel electrode and air supplied to the air electrode, and the anode off gas is discharged from the fuel electrode and the cathode off gas is discharged from the air electrode;
The fuel cell includes: an inflow portion into which the anode off gas flows, and a permeation portion partitioned from the inflow portion by a separation membrane that separates at least one of carbon dioxide and water vapor from the anode off gas; A separation unit for delivering regenerated fuel gas having a reduced concentration of at least one of steam;
An air supply unit for supplying air to the permeation unit as a sweep gas;
A permeation gas combustion introduction path for introducing the permeation portion exhaust gas discharged from the permeation portion directly or indirectly into a combustion portion for combusting a combustible gas;
A first heat exchange unit provided upstream of the separation unit and performing heat exchange between the anode off gas and air from the air supply unit;
Fuel cell system equipped with The fuel cell system according to claim 1 , wherein the first heat exchange unit exchanges heat between the anode off gas and the air from the air supply unit in a cocurrent flow type. An air heating unit provided between the air supply unit and the first heat exchange unit and raising the temperature of the air from the air supply unit;
A control unit that controls the temperature of the air flowing out of the air heating unit according to the temperature of the separation unit;
The fuel cell system according to claim 1 or 2 , further comprising: The fuel cell system according to claim 3 , wherein a flow rate of air flowing from the air supply unit into the first heat exchange unit is constant. The fuel cell system according to any one of claims 1 to 4 , further comprising: a control unit that controls a flow rate of air flowing into the first heat exchange unit according to a temperature of the separation unit. 6. The heat exchange apparatus according to claim 1 , further comprising: a second heat exchange unit performing heat exchange between the anode off gas flowing upstream of the first heat exchange unit and the regenerated fuel gas. The fuel cell system according to claim 1. It has a heat exchange part which performs heat exchange between the transmission part exhaust gas discharged from the transmission part and the combustion exhaust gas discharged from the combustion part,
The fuel cell system according to any one of claims 1 to 6 , wherein the permeating portion exhaust gas is heated by heat exchange in the heat exchange portion and supplied to the air electrode. The fuel cell system according to any one of claims 1 to 7 , further comprising a blower that supplies air to the air electrode separately from the air supply unit.   A fuel cell which generates electricity by a fuel gas supplied to the fuel electrode and air supplied to the air electrode, and the anode off gas is discharged from the fuel electrode and the cathode off gas is discharged from the air electrode;
  The fuel cell includes: an inflow portion into which the anode off gas flows, and a permeation portion partitioned from the inflow portion by a separation membrane that separates at least one of carbon dioxide and water vapor from the anode off gas; A separation unit for delivering regenerated fuel gas having a reduced concentration of at least one of steam;
  An air supply unit for supplying air to the permeation unit as a sweep gas;
  A permeation gas combustion introduction path for introducing the permeation portion exhaust gas discharged from the permeation portion directly or indirectly into a combustion portion for combusting a combustible gas;
  A heat exchange unit for exchanging heat between the transmission unit exhaust gas discharged from the transmission unit and the combustion exhaust gas discharged from the combustion unit;
  The fuel cell system, wherein the permeation part exhaust gas is heated by heat exchange in the heat exchange part and supplied to the air electrode.   A fuel cell which generates electricity by a fuel gas supplied to the fuel electrode and air supplied to the air electrode, and the anode off gas is discharged from the fuel electrode and the cathode off gas is discharged from the air electrode;
  The fuel cell includes: an inflow portion into which the anode off gas flows, and a permeation portion partitioned from the inflow portion by a separation membrane that separates at least one of carbon dioxide and water vapor from the anode off gas; A separation unit for delivering regenerated fuel gas having a reduced concentration of at least one of steam;
  An air supply unit for supplying air to the permeation unit as a sweep gas;
  A permeation gas combustion introduction path for introducing the permeation portion exhaust gas discharged from the permeation portion directly or indirectly into a combustion portion for combusting a combustible gas;
  A blower for supplying air to the air electrode separately from the air supply unit;
  A fuel cell system equipped with The permeating gas combustion introduction path includes an oxidizing gas introduction path for introducing the permeating portion exhaust gas discharged from the permeating portion to the air electrode, and a cathode off for introducing cathode off gas discharged from the air electrode to the combustion portion. The fuel cell system according to any one of claims 1 to 10 , further comprising: a combustion introduction pipe. The fuel cell includes a first fuel cell for delivering anode off to the inlet of the separation unit, and a second fuel cell the regeneration fuel gas is supplied to the fuel electrode as the fuel gas, a claim The fuel cell system according to any one of claims 1 to 11 . The fuel cell system according to any one of claims 1 to 10, wherein the air supply unit further supplies air to the air electrode.

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