JP2004087350A - Solid electrolyte fuel cell and solid electrolyte fuel cell power generation provision - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte fuel cell capable of removing surplus reaction heat in order to retain a temperature of a battery part at a prescribed temperature without supplying a large amount of air and with the minimum amount of the necessary air. <P>SOLUTION: (1) An air heating tube to supply air to a battery room 39 is installed, the air is heated and supplied recovering reaction heat of power generation by supplying the air through the air heating tube, the surplus cell reaction heat is absorbed by heating the air circulated in the air heating tube 39, the amount of air supply is reduced by decreasing air temperature at an inlet, and loss of exhaust gas is decreased by reducing a potential heat of the exhaust air and the exhaust gas. (2) A recirculation tube 51 and a recirculation exhaust air mixing device (for example, an ejector 52) are installed between an air exhaust tube 49 and an air supply tube 50, and the exhaust air is mixed into the supply air, thus raising the temperature of the supply air, then the amount of the air supply is reduced by decreasing the inlet temperature, and the loss of the exhaust gas is decreased by reducing the potential heat of the exhaust air and the exhaust gas. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid oxide fuel cell (SOFC) and a solid oxide fuel cell power generation facility.
[0002]
[Prior art]
The configuration of a conventional solid oxide fuel cell (SOFC) will be described with reference to FIGS. FIG. 5 is a perspective view showing a schematic configuration of a conventional SOFC, and FIG. 6 is a schematic cross section of the conventional SOFC.
[0003]
The SOFC 1 is a fuel cell that operates at a high temperature (900 to 1000 ° C. when the electrolyte is YSZ (Yttria Stabilized Zirconia)), and is housed in a container (casing) 2 internally covered with a heat insulating and heat insulating material. The interior of the casing 2 is partitioned from above by a fuel chamber tube sheet 3, an exhaust gas chamber tube sheet 4, an air chamber tube sheet 5, and an exhaust air chamber tube sheet 6. The fuel chamber 7, the exhaust gas chamber 8, the battery chamber 9, the air A chamber 10 and an exhaust air chamber 11 are formed. The air chamber tube sheet 5 is provided with a large number of dispersion holes 5a that communicate the battery chamber 9 and the air chamber 10.
[0004]
A battery tube 12 is provided inside the battery chamber 9, and the battery tube 12 has a double tube structure of an outer tube 13 and an inner tube 14. On the surface of the outer tube 13 of the battery tube 12, a battery having a fuel electrode, an electrolyte, and an air electrode is formed. The inner tube 14 and the outer tube 13 of the double tube battery tube 12 are supported by the fuel chamber tube sheet 3 and the exhaust gas chamber tube sheet 4, respectively. Both ends of the inner tube 14 are open, the lower end of the outer tube 13 is closed, and only the upper end is open.
[0005]
Inside the battery chamber 9, an exhaust air pipe 20 having both ends opened is disposed. The lower end of the exhaust air pipe 20 is supported by the exhaust air chamber tube plate 6 with the lower end opened to the exhaust air chamber 11. The upper end extends into the battery chamber 9 through the chamber 10 and the upper end is open to the battery chamber 9.
[0006]
A fuel supply pipe 15 is connected to the fuel chamber 7, and an exhaust gas discharge pipe 16 is connected to the exhaust gas chamber 8. Further, an air supply pipe 17 is connected to the air chamber 10, and an air discharge pipe 18 is connected to the exhaust air chamber 11.
[0007]
The fuel supplied from the fuel supply pipe 15 to the fuel chamber 7 is sent from the fuel chamber 7 to the inner pipe 14, is inverted at the lower end of the inner pipe 14, and rises in the annular portion between the inner pipe 14 and the outer pipe 13. It is sent to the exhaust gas chamber 8. The air supplied from the air supply pipe 17 to the air chamber 10 is supplied to the battery chamber 9 from the dispersion holes 5a. The exhaust air that has undergone a battery reaction with the battery on the surface of the outer tube 13 is sent from the upper end to the exhaust air tube 20, and sent from the lower end of the exhaust air tube 20 to the exhaust air chamber 11.
[0008]
In the above-described SOFC 1, 40 to 50% of the chemical energy held by the supplied fuel is directly converted to air, and 40 to 50% of the reaction heat (the change in binding energy and the internal resistance (Joule heat etc. ) Is generated, and this is collectively referred to as heat of reaction), and the remainder becomes unreacted components.
[0009]
On the other hand, since the SOFC 1 operates at 900 to 1000 ° C., it is necessary to uniformly maintain the entire area of the battery chamber 9 at a predetermined appropriate temperature (Top). That is, in order to continuously generate stable power, a predetermined amount of fuel and reaction air are heated to a temperature suitable for maintaining the temperature level and supplied to the battery unit, and the reaction products and unreacted materials are supplied. It is necessary to keep the battery operating conditions constant by performing continuous discharge of excess heat and continuous discharge of excess reaction heat.
[0010]
[Problems to be solved by the invention]
Regarding the removal of reaction heat and the uniformization of the temperature inside the battery chamber, the following four methods are considered as methods for discharging excess reaction heat to maintain the temperature of the battery unit at a predetermined temperature.
[0011]
a. Absorption of reaction heat by internal reforming of fuel (endothermic reaction)
The fuel component effective for the cell reaction in the SOFC 1 is H ₂ And CO, for example, the fuel is methane (CH ₄ ) If reformed, CO and H ₂ It is necessary to Since this reaction is an endothermic reaction as described below, a part of the reaction heat can be recovered as fuel by causing the reforming reaction to be performed near the battery unit (internal reforming).
CH ₄ + H ₂ O → CO + 3H ₂ -206.3 kJ / mol
However, the lower calorific value of methane is 801 kJ / mol, and if about 50% of the heat is reaction heat, the reaction heat is about 400 kJ / mol. Therefore, temperature control (reaction heat removal) is required only by internal reforming. Can not.
[0012]
b. Fuel and reaction air supply temperature drop
Since the necessary heat removal cannot be performed only by the internal reforming, it is necessary to supply the fuel Wf (kg) and the air Wa (kg) at a temperature (Tfi, Tai) equal to or lower than a predetermined battery operating temperature (Top). . The amount of heat absorbed by air and fuel can be expressed by the following equation.
Qaf = Wa * Ca * (Top-Tai) + Wf * Cf * (Top-Tfi)
Here, Ca and Cf are specific heats of air and fuel, respectively.
[0013]
When the internal reforming is performed and the reaction heat absorption (temperature control) is performed by supplying the fuel and the air at a low temperature, the required air temperature is, for example, about 300 ° C. It is necessary to supply. When such low-temperature air and fuel are supplied to the SOFC 1, the temperature of the introduction portion becomes lower than the battery operating temperature, and the battery function is significantly reduced. As a result, the amount of power generation with reduced battery efficiency decreases (the amount of power generation per battery area decreases), and the battery needs to be upsized. That is, lowering the supply temperature of the battery unit to an appropriate temperature or less is not a reasonable measure.
[0014]
c. Increase air volume
B. Since the decrease in the supply air temperature is limited from the viewpoint of the battery function as described in the section, the difference between the supply air temperature Tai and the battery operation temperature Top is reduced, and the amount of excess reaction heat absorbed by increasing the supply air amount Wa. There is a way to increase. That is, utilizing the heat retained in the exhaust air and exhaust gas from the battery, the temperature of the supplied air is raised to an appropriate temperature near the battery operating temperature by an external heat exchanger, and the excess heat is absorbed and removed by increasing the amount of supplied air. This is a method of maintaining the temperature at an appropriate temperature Top.
[0015]
In this method, there is a problem in that the heat loss increases due to an increase in the amount of heat exhausted (exhaust gas holding heat) due to an increase in the amount of exhaust air, the efficiency decreases due to an increase in fan power, and the size of the heat exchanger increases. .
[0016]
d. Heat removal by cooling medium
A method of removing heat by installing a heat exchanger using a third heat removal medium inside the battery, or a method of injecting steam can be applied. Temperature drop and c. The power generation efficiency is reduced due to the increase in the amount of heat discharged from the battery section to the outside and the increase in the auxiliary power.
[0017]
In the SOFC 1 having the above configuration, air is supplied by a ventilator, and the air is heated by an air heater between a combustion gas obtained by mixing exhaust gas and exhaust gas and burning. Then, the heat-exchanged combustion gas is recovered by the exhaust heat recovery boiler and released from the chimney to the atmosphere. In the exhaust heat recovery boiler, the feed water is turned into saturated water or steam by the heat of the combustion gas, and the generated saturated water or steam is supplied to necessary equipment.
[0018]
In a plant to which such an SOFC 1 is applied, the temperature of the supply air is raised to a temperature equal to or higher than the functional temperature of the SOFC 1 (however, it is not sufficiently high), and heat removal is performed by absorbing excess reaction heat by increasing the amount of air. The method has been adopted.
[0019]
For this reason, the amount of exhaust gas increases and the amount of heat retained in the exhaust gas increases, causing a problem of a decrease in power generation efficiency of the battery and a decrease in plant performance due to an increase in power of the ventilator. Further, there has been a problem that an air heater for heating air by a combustion gas becomes large, and the retained heat of the combustion gas (exhaust gas) is lost due to the high temperature of the air.
[0020]
That is, since the SOFC 1 has no air heater installed inside the battery chamber 9 (not internal heating), the heat generated by the battery reaction is not used for internal heating of the air inside the battery. Therefore, it is necessary to supply the battery with air heated to a temperature close to the battery operating temperature in advance by an air heater (external air heater) installed outside the battery chamber.
[0021]
For this reason, the reaction heat absorption amount of air per unit flow rate (endothermic effect) is small, so it is necessary to increase the air amount (air ratio> 2.5) in order to discharge excess heat of reaction. An increase in the amount of air, that is, an increase in the amount of exhaust gas and an increase in heat possessed by the exhaust gas, a reduction in the amount of power generation at the transmitting end of the battery with an increase in the size of the external heat exchanger and an increase in auxiliary power, that is, a decrease in efficiency. . Further, the heat loss of the waste heat boiler also increases, and the plant thermal efficiency decreases.
[0022]
As described above, in a plant to which the SOFC 1 is applied, when the endothermic removal of the reaction heat in the battery chamber (internal heating of air) is small, it is necessary to increase the amount of air, increase the heat loss possessed by the exhaust gas, and reduce the external heat. The increase in the size of auxiliary devices such as exchangers and ventilators and the increase in power consumption cause a decrease in power generation efficiency and plant thermal efficiency.
[0023]
The present invention has been made in view of the above circumstances, and a solid that can remove excess reaction heat for maintaining the temperature of a battery unit at a predetermined temperature by supplying a necessary minimum amount of air without supplying a large amount of air. An object is to provide an electrolyte fuel cell.
[0024]
The present invention has been made in view of the above circumstances, and a solid that can remove excess reaction heat for maintaining the temperature of a battery unit at a predetermined temperature by supplying a necessary minimum amount of air without supplying a large amount of air. It is an object of the present invention to provide a solid electrolyte fuel cell power generation facility equipped with an electrolyte fuel cell.
[0025]
[Means for Solving the Problems]
In order to achieve the above object, the solid electrolyte fuel cell according to the present invention is characterized in that the fuel supplied to either the inside or outside of the tube and the oxygen in the air supplied to either outside or inside the tube where fuel is not supplied are provided. A plurality of fuel cell tubes that generate electricity by causing a cell reaction between the fuel cell and the electrolyte, provide an air heating tube at a portion to which air is supplied, and recover the reaction heat of the power generation by supplying air through the air heating tube. The air is heated and supplied.
[0026]
And in the solid electrolyte fuel cell according to claim 1,
It is equipped with a recirculation system that recirculates part of the exhaust air after the reaction to the inlet side of the air heating pipe, and mixes the exhaust air with the air supplied to the air heating pipe to raise the temperature of the air. I do.
[0027]
Further, in the solid electrolyte fuel cell according to any one of claims 1 or 2,
A plurality of air heating tubes are provided, and a uniform maintaining mechanism for uniformly maintaining the pressure of air supplied to the air heating tubes is provided.
[0028]
In order to achieve the above object, the solid electrolyte fuel cell according to the present invention is characterized in that the fuel supplied to either the inside or outside of the tube and the oxygen in the air supplied to either outside or inside the tube where fuel is not supplied are provided. A plurality of fuel cell tubes that generate electricity by causing a cell reaction through the electrolyte through an electrolyte, and a recirculation system that recirculates a part of the exhausted air after the reaction to the air supply unit. It is characterized in that the temperature of the air mixed and supplied is increased.
[0029]
Further, in the solid electrolyte fuel cell according to any one of claims 1 to 4,
A reforming catalyst for reforming the fuel is provided on the wall of the pipe, and a part of the reaction heat of the power generation is recovered by the heat absorption by the fuel reforming reaction and the air is supplied through the air heating pipe to generate the remaining reaction heat of the power generation. It is characterized by heating and supplying air.
[0030]
Further, in the solid electrolyte fuel cell according to claim 5,
The reforming catalyst is a fuel electrode.
[0031]
Further, in the solid electrolyte fuel cell according to any one of claims 1 to 6,
Fuel is supplied into the tube, and a fuel electrode, an electrolyte, and an air electrode are provided on an outer wall of the tube.
[0032]
The solid electrolyte fuel cell of the present invention for achieving the above object,
A fuel chamber provided inside the upper part of the container,
An exhaust gas chamber provided at a lower portion of the fuel chamber and separated by a fuel chamber tube sheet;
A battery chamber provided at a lower portion of the exhaust gas chamber and separated by an exhaust gas tube tube;
An exhaust air chamber provided at a lower portion of the battery chamber and partitioned by an exhaust air chamber tube sheet;
An air chamber provided below the exhaust air chamber and partitioned by an air chamber tube sheet;
A fuel inner pipe whose both ends are open and whose upper end is open to the fuel chamber and whose lower end is arranged in the battery chamber,
A porous fuel outer pipe in which the lower end is closed and the upper end is opened and arranged outside the fuel inner pipe, the lower end covers the opening of the fuel inner pipe, and the upper end is arranged to be open to the exhaust gas chamber,
A large number of exhaust air exhaust holes provided in the exhaust air chamber tube sheet,
An air heating tube whose both ends are open and whose upper end is arranged above the battery chamber and whose lower end is open to the air chamber;
Battery cells arranged on the outer periphery of the fuel outer tube,
When fuel is supplied to the fuel chamber, fuel is sent from the lower end to the fuel outer pipe through the fuel inner pipe, and air is supplied to the air chamber. Sent,
Fuel passing through the wall of the porous fuel outer tube and oxygen in the air undergo a battery reaction via the electrolyte to generate power,
Exhaust gas containing unburned fuel in the fuel outer tube flows through the fuel outer tube and is sent to the exhaust gas chamber, and exhaust air of the battery chamber is sent to the exhaust air chamber through the exhaust air exhaust hole,
The air flowing through the air heating tube is heated by the reaction heat of power generation
It is characterized by the following.
[0033]
And in the solid electrolyte fuel cell according to claim 8,
A plurality of air heating pipes are provided, and an orifice is provided at an inlet of the air heating pipe so that the amount of air supplied to the plurality of air heating pipes becomes uniform.
[0034]
Further, in the solid electrolyte fuel cell according to claim 8 or 9,
A recirculation system for recirculating a part of the exhaust air discharged from the exhaust air chamber to the air chamber is provided, and the temperature of the air is increased by mixing the exhaust air into the air supplied to the air chamber.
[0035]
Further, in the solid electrolyte fuel cell according to claim 10,
A fuel electrode, an electrolyte and an air electrode are provided on the outer wall of the fuel outer tube,
The fuel electrode becomes a reforming catalyst for reforming the fuel,
It is characterized by recovering a part of the reaction heat of power generation by heat absorption by the fuel reforming reaction and recovering and removing all the reaction heat of power generation by heating the air flowing through the air heating tube with the remainder of the reaction heat of power generation. .
[0036]
The solid oxide fuel cell power generation equipment of the present invention for achieving the above object,
A solid electrolyte fuel cell according to any one of claims 1 to 11,
A fuel supply system for supplying fuel to the solid oxide fuel cell,
Mixing means for mixing and burning exhaust air and exhaust gas of the solid oxide fuel cell,
Air heating means for heating the air by performing heat exchange with air sent from the air supply means while the combustion gas burned by the mixing means is sent,
An air supply system for supplying the air heated by the air heating means to the solid oxide fuel cell, and an exhaust heat recovery boiler to which the combustion gas exchanged by the air heating means is sent.
It is characterized by having.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
The configuration of the solid oxide fuel cell (SOFC) of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing a schematic configuration of an SOFC according to an embodiment of the present invention, FIG. 2 is a schematic cross section of the SOFC according to an embodiment of the present invention, and FIG. 3 shows details of a battery tube. The cross section is shown.
[0038]
As shown in FIGS. 1 and 2, the SOFC 31 is a fuel cell that operates at a high temperature (900 to 1000 ° C. when the electrolyte is YSZ (Yttria Stabilized Zirconia)), and has a container (casing) internally attached with a heat insulating and heat insulating material. ) 32. The interior of the casing 32 is partitioned from above by a fuel chamber tube sheet 33, an exhaust gas chamber tube sheet 34, an exhaust air chamber tube sheet 35, and an air chamber tube sheet 36, and the fuel chamber 37, the exhaust gas chamber 38, the battery chamber 39, and the exhaust chamber. An air chamber 40 and an air chamber 41 are formed. The exhaust air chamber tube plate 35 is provided with a large number of exhaust air exhaust holes 35a that communicate the battery chamber 39 and the exhaust air chamber 40.
[0039]
A large number of battery tubes 42 are provided inside the battery chamber 39, and the battery tube 42 has a double tube structure of an outer fuel tube 43 and an inner fuel tube 44. The inner tube 14 and the outer tube 13 of the double tube battery tube 12 are supported by a fuel chamber tube sheet 33 and an exhaust gas chamber tube sheet 34, respectively.
[0040]
Both ends of the fuel inner pipe 44 are open, and the lower end of the fuel outer pipe 13 is closed and only the upper end is open. Both ends of the fuel inner tube 14 are open and the upper end thereof is open to the fuel chamber 37, and the lower end thereof is disposed in the battery chamber 39. The outer fuel tube 13 is arranged outside the inner fuel tube 14, and the lower end portion covers the opening of the inner fuel tube 14 and the upper end portion opens to the exhaust gas chamber 38. The outer fuel tube 13 is formed of a porous material.
[0041]
A large number of air heating pipes 45 having both ends opened are disposed inside the battery chamber 39. The air heating pipes 45 penetrate the exhaust gas chamber 38, the exhaust air chamber tube plate 35, and the air chamber tube plate 36, and the lower end thereof. Are supported by the air chamber tube sheet 36 in a state where they are open to the air chamber 41. Restrictors 46 are provided at the inlets of the air heating tubes 45, respectively, so that the pressure of the air supplied from the air chamber 41 to each of the air heating tubes 45 is maintained uniformly (uniform maintenance mechanism).
[0042]
In addition, as the uniformity maintaining mechanism, a mechanism that changes the flow path area of the air chamber 41 to maintain the pressure of the air supplied to the respective air heating tubes 45 uniform may be employed.
[0043]
A fuel supply pipe 47 is connected to the fuel chamber 37, and an exhaust gas discharge pipe 48 is connected to the exhaust gas chamber 38. Further, an air discharge pipe 49 is connected to the discharge air chamber 40, and an air supply pipe 50 is connected to the air chamber 41.
[0044]
As shown in FIG. 2, a recirculation pipe 51 is provided between the air discharge pipe 49 and the air supply pipe 50 to recirculate a part of the high-temperature exhaust air after the reaction. The part is mixed into the air chamber 41 (the inlet side of the air heating pipe 45), and the temperature of the air supplied to the air heating pipe 45 is increased.
[0045]
An ejector 52 for increasing the pressure in the air supply pipe 50 is provided in the air supply pipe 50 at the junction of the recirculation pipe 51, and the ejector 52 forms a pressure difference between the air discharge pipe 49 and the air supply pipe 50. A part of the exhaust air from the air exhaust pipe 49 is guided to the recirculation pipe 51 and sent to the air supply pipe 50 by the pressure difference generated by the ejector 52.
[0046]
It should be noted that a booster or the like can be provided in the air supply pipe 50 instead of the ejector 52.
[0047]
As shown in FIGS. 1 and 2, a battery 53 having a fuel electrode, an electrolyte, and an air electrode is formed on the surface of the outer fuel tube 43 of the battery tube 42. The fuel electrode serves as a catalyst for reforming the fuel, and the fuel sent to the battery tube 42 is internally reformed (endothermic reaction).
[0048]
That is, as shown in FIG. 3, a battery 53 having a fuel electrode 55, an electrolyte 56, and an air electrode 57 is formed on the surface of the fuel outer tube 43 of the battery tube 42. The fuel electrode 55 is made of, for example, nickel cermet, and the fuel electrode 55 itself is a catalyst for reforming the fuel. Fuel such as methane passes through the porous fuel outer tube 43 and is reformed at the fuel electrode 55, so that hydrogen can be used. Oxygen in the air receives electrons to become oxygen ions, moves the electrolyte 56 to the fuel side, emits electrons at the fuel electrode 55, and ₂ O and CO are generated, and power is generated.
[0049]
As shown by the dotted line in FIG. 3, it is also possible to provide a reforming catalyst 59 on the outer surface of the inner fuel tube 44 of the battery tube 42 to promote the reforming.
[0050]
The fuel supplied from the fuel supply pipe 47 to the fuel chamber 37 is sent from the fuel chamber 37 to the fuel inner pipe 44 of the battery pipe 42, and is inverted at the lower end of the fuel inner pipe 44 to form the fuel inner pipe 44 and the fuel outer pipe 43. The ascending annular portion is sent to the exhaust gas chamber 38. The fuel absorbs the reaction heat due to the cell reaction in the process of descending through the fuel inner tube 44, and at the entrance of the annular portion, the temperature rises to the temperature required for the cell reaction and partially reformed to absorb the cell reaction heat. In the annular portion, a reforming reaction and a battery reaction are performed.
[0051]
The air supplied from the air supply pipe 50 to the air chamber 41 is sent to the air heating pipe 45 and rises inside the air heating pipe 45. A part of the exhaust air branched off from the air discharge pipe 49 is mixed into the air supply pipe 50 via the recirculation pipe 51 to raise the temperature of the air in the air chamber 41. The air absorbs the battery reaction heat in the process of rising in the air heating tube 45, is heated to a temperature necessary for the battery reaction, and is discharged to the battery chamber 39.
[0052]
The discharged air descends in the battery chamber 39 while performing a battery reaction, and is sent to the exhaust air chamber 40 through the gap around the through portion of the air heating tube 45 of the exhaust air chamber tube plate 35 and the exhaust air exhaust hole 35a. Can be
[0053]
In the SOFC 31 having the above-described structure, fuel flows through the battery tube 42 having a double-tube structure. In the process of descending the inner fuel tube 44, the reaction heat is lowered to absorb (heat) the reaction heat, and the annular heat is absorbed. In the process of ascending the portion, the structure is such that heat is absorbed by the reforming reaction. In addition, the air has a function of absorbing the reaction heat in the process of ascending the air heating tube 45. For this reason, the fuel has a structure having a maximum internal heat absorbing function.
[0054]
In the above-described SOFC 31, the air and the fuel have a necessary internal heat absorbing function, so that the temperature of the air supplied to the air chamber 41 and the temperature of the fuel supplied to the fuel chamber 37 can be reduced accordingly, and the amount of supplied air is reduced. be able to. Moreover, the air discharged from the air heating tube 45 to the battery chamber 39 is at an appropriate temperature level.
[0055]
Further, since a part of the exhaust air branched from the air exhaust pipe 49 is mixed into the air supply pipe 50 via the recirculation pipe 51, the inlet temperature of the supply air in the battery chamber 39 rises, and the battery chamber 39 The temperature distribution in the inside can be made more uniform.
[0056]
It is also possible to omit the recirculation pipe 51 and the ejector 52 so that a part of the exhaust air is not mixed into the air supply pipe 50. Even when a part of the exhaust air is not mixed, the supplied air can absorb the reaction heat in the process of passing through the air heating pipe 45 to increase the temperature.
[0057]
Further, it is also possible to omit the air heating pipe 45 and increase the temperature of the air only by mixing a part of the exhaust air into the air supply pipe 50. In this case, the battery chamber 39 can be simplified.
[0058]
Further, in the above-described SOFC 31, the configuration is such that the fuel is supplied to the battery chamber 39 through the fuel through the battery tube 42, but the configuration may be such that the fuel is supplied to the battery chamber 39 through the air through the battery tube 42. . In this case, the air heating tube 45 is provided at an appropriate portion capable of absorbing the reaction heat.
[0059]
The SOFC 31 of the above-described embodiment of the present embodiment absorbs excess battery reaction heat by the internal air heating means (air heating pipe 45) of the SOFC 31, and performs air heating, so that the inlet air temperature of the SOFC 31 can be reduced. For this reason, the supply air amount can be reduced. By appropriately distributing the air heating tubes 45, equalization of heat absorption can be obtained, and the temperature of the air discharged into the battery chamber 39 by optimizing the number of the air heating tubes 45 can be adjusted to an appropriate level for the battery reaction. Is obtained.
[0060]
As described above, since the air is heated by absorbing the excess heat of the reaction by the internal air heating method, the temperature of the air supplied to the SOFC 31 can be reduced, which is necessary from the viewpoint of cooling the SOFC 31 (removal of the reaction heat). By reducing the amount of air, the temperature inside the battery can be controlled to reduce the retained heat of the exhaust air and the exhaust gas, thereby reducing the exhaust gas loss.
[0061]
Further, since the inlet air temperature of the SOFC 31 can be increased by recirculating the exhaust air, the temperature inside the battery chamber 39 can be made more uniform. In particular, when the air heating tube 45 is not provided in the battery chamber 39, the inlet air of the battery chamber 39 can be raised to an appropriate temperature level.
[0062]
In addition, since the fuel tube 44 has a fuel heating function as a double tube with the battery tube 42 being a double tube, even if a low-temperature fuel that does not pass through a fuel heater is supplied, heat is absorbed by the battery reaction and the battery reaction section is absorbed. Before the fuel reaches the (lower end of the fuel inner pipe 44), the temperature can be raised to a temperature level appropriate for the cell reaction.
[0063]
Accordingly, it is possible to remove endothermic heat of reaction (temperature control) without deteriorating the battery performance, and it is possible to avoid an increase in the amount of air for exhausting the reaction heat and to avoid a decrease in efficiency.
[0064]
Further, since a catalyst material having a reforming function is used for the fuel electrode 55, the fuel electrode 55 can have a reforming function. Further, for example, by applying or mixing a material having a reforming catalyst function (catalyst 59) on the outer surface of the fuel inner tube 44, the internal reforming function can be improved, and a wide range of fuels that are difficult to reform can be used. Even this allows internal reforming.
[0065]
A power generation facility to which the SOFC 31 is applied will be described based on FIG. FIG. 4 shows a schematic system of a solid oxide fuel cell power generation facility according to an embodiment of the present invention.
[0066]
The solid oxide fuel cell power generation equipment according to the present embodiment has a SOFC 31 shown in FIGS. 1 to 3 and a system of a SOFC cogeneration plant equipped with an external air heater 61 and an exhaust heat recovery boiler 62 as air heating means. Has become. And it is a plant in which two SOFCs 31 are installed.
[0067]
Reference numeral 71 in the drawing denotes an orthogonal converter for converting the power obtained by the SOFC 31 from DC to AC.
[0068]
The exhaust gas containing unreacted components is supplied to an exhaust gas exhaust air mixer 63 as mixing means via an exhaust gas exhaust pipe 48. The exhaust air containing unreacted oxygen is supplied to an exhaust gas exhaust air mixer 63 via an air exhaust pipe 49. In the exhaust gas exhaust air mixer 63, exhaust gas containing unreacted components and exhaust air containing unreacted oxygen are mixed, and unreacted fuel burns.
[0069]
A fuel branch 69 is connected to the exhaust gas exhaust air mixer 63, and necessary fuel is supplied by opening and closing the control valve 70 in accordance with an increase in the amount of steam or hot water generated in the exhaust heat recovery boiler 62.
[0070]
The combustion gas (exhaust gas) that has become hot due to the combustion of the unreacted fuel is introduced into the external air heater 61, where the heat is exchanged with the air supplied to the SOFC 31 by the external air heater 61. The supply air at the outlet of the external air heater 61 is heated to a required temperature by the retained heat of the exhaust gas and supplied to the SOFC 31.
[0071]
Exhaust gas heat-exchanged by the external air heater 61 is sent to an exhaust heat recovery boiler 62 via an exhaust gas pipe 64, where heat of the exhaust gas is recovered and steam is generated from feed water. Exhaust gas whose heat energy has been almost recovered and has reached a predetermined temperature is discharged from the chimney 73 to the atmosphere.
[0072]
On the other hand, the pressure of the air supplied to the SOFC 31 is increased by the ventilator 65 and sent to the external air heater 61. The air heated by the external air heater 61 is supplied from the air supply pipe 50 to the SOFC 31 (air supply system). A starting combustor 66 for heating low-temperature air at the time of starting is installed in the air supply pipe 50, and fuel is supplied to the starting combustor 66 from a fuel branch 67. In the figure, reference numeral 68 denotes a control valve for opening the fuel branch 67 at the time of startup.
[0073]
After the sulfur content is removed by the desulfurizer 72, the fuel is supplied from the fuel supply pipe 47 to the SOFC 31 during normal operation (fuel supply system). During startup, the control valve 68 is opened, and fuel is supplied from the fuel branch 67 to the startup combustor 66.
[0074]
In the solid oxide fuel cell power generation equipment described above, the SOFC 31 can remove residual heat with a small amount of air, and even when supplied at a low temperature, is heated to a temperature close to the reaction temperature and supplied to the battery chamber. Even if a small external air heater 61 is used, air at a desired temperature can be obtained.
[0075]
Further, since the amount of air is small, the power consumption of the ventilator 65 for increasing the pressure is reduced, and the power transmission end power generation efficiency can be improved.
[0076]
Furthermore, since the temperature of the exhaust gas to the inlet of the exhaust heat recovery boiler 62 is maintained high and the heat recovery in the exhaust heat recovery boiler 62 is performed to reduce the heat retained in the outlet gas, the efficiency of the exhaust heat recovery boiler 62 is increased. The thermal efficiency of the plant can be improved.
[0077]
【The invention's effect】
The solid electrolyte fuel cell according to the present invention is a battery that supplies fuel supplied to either the inside or outside of the tube and oxygen in air supplied to either outside or inside the tube to which fuel is not supplied, through the electrolyte. A plurality of fuel cell tubes for reacting and generating power are provided, and an air heating tube is provided at a portion to which air is supplied, and by supplying air through the air heating tube, reaction heat of power generation is recovered and the air is heated and supplied. Therefore, by heating the air flowing through the air heating tube, excess battery reaction heat can be absorbed, and the air temperature at the inlet can be reduced to reduce the amount of supplied air.
[0078]
Therefore, the temperature of the supply air can be reduced, and the amount of air required from the viewpoint of cooling (removal of reaction heat) of the solid oxide fuel cell can be reduced, thereby controlling the internal temperature of the cell and controlling the exhaust air and exhaust gas. And the exhaust heat loss can be reduced.
[0079]
As a result, it is possible to provide a solid electrolyte fuel cell capable of removing excess heat of reaction for maintaining the temperature of the battery unit at a predetermined temperature by supplying a necessary minimum amount of air without supplying a large amount of air. .
[0080]
And in the solid electrolyte fuel cell according to claim 1,
A recirculation system that recirculates part of the exhaust air after the reaction to the inlet side of the air heating pipe is provided, and the temperature of the air is increased by mixing the exhaust air into the air supplied to the air heating pipe. By recirculating the exhaust air, the air temperature at the inlet can be increased, and the temperature inside the battery chamber can be made more uniform.
[0081]
Further, in the solid electrolyte fuel cell according to any one of claims 1 or 2,
Since a plurality of air heating pipes are provided and provided with a uniform maintenance mechanism that uniformly maintains the pressure of the air supplied to the air heating pipe,
The heating of the inlet air can be made uniform.
[0082]
The solid electrolyte fuel cell according to the present invention is a battery that supplies fuel supplied to either the inside or outside of the tube and oxygen in air supplied to either outside or inside the tube to which fuel is not supplied, through the electrolyte. Equipped with a plurality of fuel cell tubes that generate electricity by reacting, equipped with a recirculation system that recirculates part of the exhausted air after the reaction to the air supply unit, and supplied air mixed with exhausted air , The temperature of the air at the inlet can be increased with a simple configuration by recirculating the exhaust air, and the temperature inside the battery chamber can be made uniform.
[0083]
As a result, it is possible to provide a solid electrolyte fuel cell capable of removing excess heat of reaction for maintaining the temperature of the battery unit at a predetermined temperature by supplying a necessary minimum amount of air without supplying a large amount of air. .
[0084]
Further, in the solid electrolyte fuel cell according to any one of claims 1 to 4,
A reforming catalyst for reforming the fuel is provided on the wall of the pipe, and a part of the reaction heat of the power generation is recovered by the heat absorption by the fuel reforming reaction and the air is supplied through the air heating pipe to generate the remaining reaction heat of the power generation. Since the air is heated and supplied, even if a low-temperature fuel that does not pass through a fuel heater is supplied, it absorbs the reaction heat of the cell and reaches the appropriate temperature for the cell reaction before the fuel reaches the cell reaction section. The temperature can be raised to the level, the endothermic removal of reaction heat (temperature control) can be performed without lowering the battery performance, and the increase in the amount of air for exhausting the reaction heat is reduced, thereby avoiding a decrease in efficiency. .
[0085]
Further, in the solid electrolyte fuel cell according to claim 5,
Since the reforming catalyst is the fuel electrode, it becomes possible to reform the fuel at the fuel electrode.
[0086]
Further, in the solid electrolyte fuel cell according to any one of claims 1 to 6,
Since fuel is supplied into the tube and the fuel electrode, the electrolyte, and the air electrode are provided on the outer wall of the tube, the fuel has the maximum internal heat absorbing function.
[0087]
The solid electrolyte fuel cell of the present invention,
A fuel chamber provided inside the upper part of the container,
An exhaust gas chamber provided at a lower portion of the fuel chamber and separated by a fuel chamber tube sheet;
A battery chamber provided at a lower portion of the exhaust gas chamber and separated by an exhaust gas tube tube;
An exhaust air chamber provided at a lower portion of the battery chamber and partitioned by an exhaust air chamber tube sheet;
An air chamber provided below the exhaust air chamber and partitioned by an air chamber tube sheet;
A fuel inner pipe whose both ends are open and whose upper end is open to the fuel chamber and whose lower end is arranged in the battery chamber,
A porous fuel outer pipe in which the lower end is closed and the upper end is opened and arranged outside the fuel inner pipe, the lower end covers the opening of the fuel inner pipe, and the upper end is arranged to be open to the exhaust gas chamber,
A large number of exhaust air exhaust holes provided in the exhaust air chamber tube sheet,
An air heating tube whose both ends are open and whose upper end is arranged above the battery chamber and whose lower end is open to the air chamber;
Battery cells arranged on the outer periphery of the fuel outer tube,
When fuel is supplied to the fuel chamber, fuel is sent from the lower end to the fuel outer pipe through the fuel inner pipe, and air is supplied to the air chamber. Sent,
Fuel passing through the wall of the porous fuel outer tube and oxygen in the air undergo a battery reaction via the electrolyte to generate power,
Exhaust gas containing unburned fuel in the fuel outer tube flows through the fuel outer tube and is sent to the exhaust gas chamber, and exhaust air of the battery chamber is sent to the exhaust air chamber through the exhaust air exhaust hole,
Since the air flowing through the air heating pipe is heated by the reaction heat of power generation,
By heating the air flowing through the air heating tube, excess battery reaction heat can be absorbed, and the inlet air temperature can be reduced to reduce the amount of supplied air.
[0088]
Therefore, the temperature of the supply air can be reduced, and the amount of air required from the viewpoint of cooling (removal of reaction heat) of the solid oxide fuel cell can be reduced, thereby controlling the internal temperature of the cell and controlling the exhaust air and exhaust gas. And the exhaust heat loss can be reduced.
[0089]
As a result, it is possible to provide a solid electrolyte fuel cell capable of removing excess heat of reaction for maintaining the temperature of the battery unit at a predetermined temperature by supplying a necessary minimum amount of air without supplying a large amount of air. .
[0090]
And in the solid electrolyte fuel cell according to claim 8,
A plurality of air heating pipes are provided, and an orifice is provided at the inlet of the air heating pipe so that the amount of air supplied to the plurality of air heating pipes is uniform,
The heating of the inlet air can be made uniform.
[0091]
Further, in the solid electrolyte fuel cell according to claim 8 or 9,
A recirculation system that recirculates part of the exhaust air discharged from the exhaust air chamber to the air chamber is provided, and the temperature of the air is increased by mixing the exhaust air into the air supplied to the air chamber.
By recirculating the exhaust air, the air temperature at the inlet can be raised, and the temperature inside the battery chamber can be made more uniform.
[0092]
Further, in the solid electrolyte fuel cell according to claim 10,
A fuel electrode, an electrolyte and an air electrode are provided on the outer wall of the fuel outer tube,
The fuel electrode becomes a reforming catalyst for reforming the fuel,
Since a part of the heat of the power generation is recovered by the heat absorption by the fuel reforming reaction, and the air flowing through the air heating tube is heated by the remainder of the heat of the power generation to collect and remove all the heat of the power generation.
Even if a low-temperature fuel is supplied without passing through the fuel heater, the heat of the battery reaction is absorbed, and the temperature can be raised to a temperature level appropriate for the battery reaction before the fuel reaches the battery reaction section. Endothermic removal of reaction heat (temperature control) becomes possible without a decrease, and an increase in the amount of air for exhausting the reaction heat is reduced, so that a decrease in efficiency can be avoided.
[0093]
The solid oxide fuel cell power generation equipment of the present invention,
A solid electrolyte fuel cell according to any one of claims 1 to 11,
A fuel supply system for supplying fuel to the solid oxide fuel cell,
Mixing means for mixing and burning exhaust air and exhaust gas of the solid oxide fuel cell,
Air heating means for heating the air by performing heat exchange with air sent from the air supply means while the combustion gas burned by the mixing means is sent,
An air supply system for supplying the air heated by the air heating means to the solid oxide fuel cell, and an exhaust heat recovery boiler to which the combustion gas exchanged by the air heating means is sent.
With
The solid electrolyte fuel cell can remove residual heat with a small amount of air, and even if supplied at a low temperature, it is heated to a temperature close to the reaction temperature and supplied to the cell chamber. Therefore, it is possible to obtain air at a desired temperature, and because the amount of air is small, the power consumption of the power of the air supply system for increasing the pressure is reduced, and the power transmission end power generation efficiency can be improved. Since the temperature of the exhaust gas to the inlet of the exhaust heat recovery boiler is maintained high and the heat recovery in the exhaust heat recovery boiler is performed to reduce the heat retained in the outlet gas, the efficiency of the exhaust heat recovery boiler is increased to improve the thermal efficiency of the plant. Can be improved.
[0094]
As a result, a solid electrolyte fuel cell equipped with a solid electrolyte fuel cell capable of removing excess heat of reaction for maintaining the temperature of the battery unit at a predetermined temperature by supplying a necessary minimum amount of air without supplying a large amount of air It becomes possible to make equipment.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a schematic configuration of an SOFC according to an embodiment of the present invention.
FIG. 2 is a schematic sectional view of an SOFC according to an embodiment of the present invention.
FIG. 3 is a sectional view showing details of a battery tube.
FIG. 4 is a schematic system diagram of a solid oxide fuel cell power generation system according to an embodiment of the present invention.
FIG. 5 is a perspective view illustrating a schematic configuration of a conventional SOFC.
FIG. 6 is a schematic sectional view of a conventional SOFC.
[Explanation of symbols]
31 Solid Electrolyte Fuel Cell (SOFC)
32 containers (casings)
33 Fuel chamber tube sheet
34 Exhaust gas chamber tube sheet
35 Exhaust air chamber tube sheet
35a Exhaust air exhaust hole
36 Air chamber tube sheet
37 Fuel Chamber
38 Exhaust gas chamber
39 Battery room
40 Exhaust air chamber
41 air chamber
42 Battery tube
43 Outer fuel tube
44 Fuel inner pipe
45 air heating tube
46 Aperture
47 Fuel supply pipe
48 Exhaust gas exhaust pipe
49 Air exhaust pipe
50 Air supply pipe
51 Recirculation pipe
52 Ejector
53 batteries
55 Fuel electrode
56 electrolyte
57 air electrode
59 catalyst
61 External air heater
62 Waste heat recovery boiler
63 exhaust gas exhaust air mixer
64 exhaust gas pipe
65 ventilator
66 Combustor for starting
67,69 Fuel branch pipe
68, 70 control valve
71,72 orthogonal transformer
72 Desulfurization equipment
73 Chimney

Claims (12)

A fuel cell tube which generates a battery by causing a cell reaction between fuel supplied to one of the inside and outside of the tube and oxygen in air supplied to one of the outside and inside of the tube to which fuel is not supplied via an electrolyte through an electrolyte. A solid electrolyte fuel characterized by providing a plurality of air heating pipes at a portion to which air is supplied, heating the air by supplying the air through the air heating pipe, and collecting the reaction heat of the power generation to supply the air. battery. The solid electrolyte fuel cell according to claim 1,
It is equipped with a recirculation system that recirculates part of the exhaust air after the reaction to the inlet side of the air heating pipe, and mixes the exhaust air with the air supplied to the air heating pipe to raise the temperature of the air. Solid electrolyte fuel cell. The solid electrolyte fuel cell according to any one of claims 1 or 2,
A solid electrolyte fuel cell comprising a plurality of air heating tubes and a uniformity maintaining mechanism for uniformly maintaining the pressure of air supplied to the air heating tubes. A fuel cell tube which generates a battery by causing a cell reaction between fuel supplied to one of the inside and outside of the tube and oxygen in air supplied to one of the outside and inside of the tube to which fuel is not supplied via an electrolyte through an electrolyte. A plurality of recirculation systems are provided for recirculating a part of the exhaust air after the reaction to the air supply unit, and the temperature of the supplied air is increased by mixing the exhaust air with the supplied air. Solid electrolyte fuel cell. The solid electrolyte fuel cell according to any one of claims 1 to 4,
A reforming catalyst for reforming the fuel is provided on the wall of the pipe, and a part of the reaction heat of the power generation is recovered by the heat absorption by the fuel reforming reaction and the air is supplied through the air heating pipe to generate the remaining reaction heat of the power generation. A solid electrolyte fuel cell, wherein air is supplied by heating. The solid electrolyte fuel cell according to claim 5,
A solid electrolyte fuel cell, wherein the reforming catalyst is a fuel electrode. The solid electrolyte fuel cell according to any one of claims 1 to 6,
A solid electrolyte fuel cell, wherein fuel is supplied into a tube, and a fuel electrode, an electrolyte, and an air electrode are provided on an outer wall of the tube. A fuel chamber provided inside the upper part of the container,
An exhaust gas chamber provided at a lower portion of the fuel chamber and separated by a fuel chamber tube sheet;
A battery chamber provided at a lower portion of the exhaust gas chamber and separated by an exhaust gas tube tube;
An exhaust air chamber provided at a lower portion of the battery chamber and partitioned by an exhaust air chamber tube sheet;
An air chamber provided below the exhaust air chamber and partitioned by an air chamber tube sheet;
A fuel inner pipe whose both ends are open and whose upper end is open to the fuel chamber and whose lower end is arranged in the battery chamber,
A porous fuel outer pipe in which the lower end is closed and the upper end is opened and arranged outside the fuel inner pipe, the lower end covers the opening of the fuel inner pipe, and the upper end is arranged to be open to the exhaust gas chamber,
A large number of exhaust air exhaust holes provided in the exhaust air chamber tube sheet,
An air heating tube whose both ends are open and whose upper end is arranged above the battery chamber and whose lower end is open to the air chamber;
Battery cells arranged on the outer periphery of the fuel outer tube,
When fuel is supplied to the fuel chamber, fuel is sent from the lower end to the fuel outer pipe through the fuel inner pipe, and air is supplied to the air chamber. Sent,
Fuel passing through the wall of the porous fuel outer tube and oxygen in the air undergo a battery reaction via the electrolyte to generate power,
Exhaust gas containing unburned fuel in the fuel outer tube flows through the fuel outer tube and is sent to the exhaust gas chamber, and exhaust air of the battery chamber is sent to the exhaust air chamber through the exhaust air exhaust hole,
A solid electrolyte fuel cell, wherein air flowing through an air heating tube is heated by reaction heat of power generation. The solid electrolyte fuel cell according to claim 8,
A solid electrolyte fuel cell, wherein a plurality of air heating tubes are provided, and an orifice is provided at an inlet of the air heating tube so that the amount of air supplied to the plurality of air heating tubes is uniform. The solid electrolyte fuel cell according to claim 8 or 9,
A solid body that has a recirculation system that recirculates part of the exhaust air discharged from the exhaust air chamber to the air chamber, and increases the temperature of the air by mixing the exhaust air into the air supplied to the air chamber. Electrolyte fuel cell. The solid electrolyte fuel cell according to claim 10,
A fuel electrode, an electrolyte and an air electrode are provided on the outer wall of the fuel outer tube,
The fuel electrode becomes a reforming catalyst for reforming the fuel,
It is characterized by recovering a part of the reaction heat of power generation by heat absorption by the fuel reforming reaction and recovering and removing all the reaction heat of power generation by heating the air flowing through the air heating tube with the remainder of the reaction heat of power generation. Solid electrolyte fuel cell. A solid electrolyte fuel cell according to any one of claims 1 to 11,
A fuel supply system for supplying fuel to the solid oxide fuel cell,
Mixing means for mixing and burning exhaust air and exhaust gas of the solid oxide fuel cell,
Air heating means for heating the air by performing heat exchange with air sent from the air supply means while the combustion gas burned by the mixing means is sent,
A solid electrolyte fuel comprising: an air supply system that supplies air heated by air heating means to a solid electrolyte fuel cell; and a waste heat recovery boiler to which combustion gas heat-exchanged by the air heating means is sent. Battery power generation equipment.

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