JP4369685B2 - Operation method of fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides a fuel cell.PondRegarding the operation method, in particular, it is possible to start up quickly and to achieve high power generation efficiency.PondIt relates to the driving method.
[0002]
[Prior art]
In recent years, various fuel cells in which a stack of fuel cells is accommodated in a storage container have been proposed as next-generation energy.
[0003]
  Solid electrolyteformA fuel cell has multiple solid electrolytesformA fuel cell stack composed of fuel cells is accommodated in a storage container, and is operated at a temperature of about 1000 ° C.
[0004]
  Solid electrolyteformThe fuel cell needs to heat the fuel cell up to this temperature, and there is a problem that it takes a long time to substantially generate power.
[0005]
Further, as a method for supplying hydrogen used as a fuel when generating electricity, a steam reforming method is used in which hydrogen such as natural gas reacts with steam to generate hydrogen. This reaction is also performed at 500 to 900 ° C. Therefore, there is also a problem that it takes a long time to heat the fuel reformer that performs the reforming reaction.
[0006]
The long time required for heating the fuel cell and the fuel reformer in this way is a problem that the power generation efficiency is low.
[0007]
  In order to solve such problems, solid electrolyteformA fuel reformer of a fuel cell is disposed in a storage container that houses a fuel cell stack, and heat generated during power generation is used for a steam reforming reaction to increase thermal efficiency (for example, Patent Document 1).
[0008]
  PolymerformIn fuel cells, fuel reforming is performed by a partial oxidation method, which is an exothermic reaction, or a combination of a partial oxidation method and a steam reforming method (hereinafter referred to as autothermal method) to shorten the start-up time of the reformer. Thus, a reformer that does not require a heating source has been reported (see, for example, Patent Document 2).
[0009]
[Patent Document 1]
JP-A-8-287937
[0010]
[Patent Document 2]
JP 2001-185196 A
[0011]
[Problems to be solved by the invention]
However, in the system in which the above-described fuel reformer is disposed in the storage container, the reforming catalyst is filled in the fuel supply chamber above the power generation chamber, and the radiant heat from the power generation chamber and the heat transfer of the exhaust gas are used as a heat source. However, there are problems that the distance from the heat source is increased and it takes time to raise the temperature of the fuel reformer, and that heating to a temperature higher than the power generation temperature is impossible.
[0012]
In addition, when the fuel cell output is reduced and the load is low, the amount of heat generated by the power generation reaction is reduced, so that the temperature of the power generation chamber is lowered and the amount of heat necessary for the steam reforming reaction may be insufficient. Furthermore, since an external heating source is required at the time of start-up, there is a problem that the thermal efficiency is lowered.
[0013]
In addition, when fuel reforming is always performed by a partial oxidation method or a combination of a partial oxidation method and a steam reforming method, the amount of hydrogen produced is less than that of the steam reforming method, resulting in a decrease in power generation efficiency. There is a problem.
[0014]
That is, the conventional method has a problem that the start-up time is not yet shortened and high power generation efficiency is not sufficiently achieved.
[0015]
  The present invention can significantly shorten the startup time and has high power generation efficiency.PondThe purpose is to provide a driving method.
[0016]
[Means for Solving the Problems]
  Fuel cell of the present inventionDriving methodA plurality of fuel cells and a fuel reformer in a storage containerWhenAnd the fuel gas from one end of the fuel cell is burned in the storage container, and the fuel reformerTheExposure to combustion gasesWhen the temperature of the fuel reformer is lower than the partial oxidation reaction start temperature, the fuel reformer is heated by the combustion heat of the combustion gas and / or stored. When the heating device is housed in the container and the fuel reformer is heated by the heat from the heating device, and the temperature of the fuel reformer is equal to or higher than the partial oxidation reaction start temperature and lower than the steam reformable temperature The fuel reformer is heated by the reaction heat of the partial oxidation reaction and the combustion heat of the combustion gas to perform partial oxidation reforming, and the temperature of the fuel reformer is equal to or higher than the steam reformable temperature and the fuel When the battery is not in a steady state, the fuel reformer is heated by the reaction heat of the partial oxidation reaction, the heat of combustion by the combustion gas, and the endothermic reaction of the steam reforming reaction to perform partial oxidation reforming and steam reforming. The fuel cell There the case of steady state, performs steam reforming to heat said fuel reformer by combustion heat by the combustion gasIt is characterized by that.
[0037]
At the start of the fuel cell, the temperature of the fuel reformer is room temperature. From the room temperature to the partial oxidation reaction start temperature, the reformed gas and the oxygen-containing gas introduced into the fuel cell through the fuel reformer The fuel reformer is heated to the partial oxidation reaction start temperature by ejecting the gas to be reformed mixed with the gas from one end of the fuel cell and burning it.
[0038]
Moreover, you may heat to the same temperature by using an auxiliary heat source (heating apparatus) instead of combustion, or using both together.
[0039]
  After reaching the partial oxidation reaction start temperature, the reformed gas and oxygen-containing gasWhenHowever, since the partial oxidation reaction starts, the fuel reformer is spontaneously heated without being heated from the outside by the reaction heat.
[0040]
When the auxiliary heat source (heating device) is used in this state, the heating from the auxiliary heat source (heating device) may be stopped.
[0041]
However, heating by combustion from one end of the fuel cell is indispensable for raising the temperature of the fuel cell, maintaining the temperature, and further maintaining the temperature of the fuel reformer in a steady state. There is.
[0042]
Therefore, in this temperature range, the fuel reformer is heated by the reaction heat of the partial oxidation reaction and the combustion heat.
[0043]
  After reaching the steam reforming temperature, the reaction heat of the partial oxidation reactionWhenCombustion heatWhenIn order to prevent deterioration of the fuel reformer due to excessive heating, destruction of the fuel reformer, and degradation of the performance of the reforming catalyst,,Oxygen-containing gasWhen,water vaporWhenBy mixing the partial oxidation reaction and the steam reforming reaction, which is an endothermic reaction.UseThe fuel reformer temperature is controlled by the autothermal method.
[0044]
When heating is required, the oxygen-containing gas ratio is increased and the water vapor ratio is decreased to make the total heat related to the reforming reaction exothermic. Temperature control is performed by making the total heat quantity related to the reforming reaction endothermic reaction by increasing the ratio.
[0045]
After the fuel cell is sufficiently heated and reaches a steady state where power generation is possible, the fuel reforming is performed by switching to the steam reforming method that generates the largest amount of hydrogen and has the highest power generation efficiency.
[0046]
At this time, since the auxiliary heat source is no longer necessary, the heating source is only the combustion heat.
[0047]
  Further, the fuel cell operating method of the present invention includes a plurality of fuel cells and a fuel reformer in a storage container.WhenAnd the fuel gas from one end of the fuel cell is burned in the storage container, and the fuel reformerTheExposure to combustion gasesYouA method of operating a fuel cell, wherein the temperature of the fuel reformerPartWhen the temperature is lower than the partial oxidation start temperatureThe aboveCombustion heat from combustion gasTo heat the fuel reformer and / or to store the heating device in the storage container andBy heat from the heating deviceAboveHeating the fuel reformer,The temperature of the fuel reformer isAbove the partial oxidation reaction start temperatureAnd the fuel cellStationaryNot in stateIn some cases, the reaction heat of the partial oxidation reactionAboveCombustion heat from combustion gasWhenByAboveHeating the fuel reformerThePartial oxidation reforming,The fuel cellFor steady state,AboveDue to combustion heat from combustion gasI saidHeating the fuel reformerTheIt is characterized by performing steam reforming.
[0048]
At the start of the fuel cell, the temperature of the fuel reformer is normal temperature, so the catalyst is heated in the same manner as described above from normal temperature to the partial oxidation reaction start temperature.
[0049]
  Unlike the above from the partial oxidation reaction start temperature, DepartmentReaction heat of the partial oxidation reaction and fuel from one end of the fuel cellBakedBy gasUntil the fuel cell reaches a steady stateBy performing the heating, the heat release from the fuel reformer can be used for raising the temperature of the fuel cell, so that it can be started more quickly. After reaching the steady state, the same as above.
[0050]
  Further, the fuel cell operating method of the present invention includes a plurality of fuel cells and a fuel reformer in a storage container.WhenThe fuel gas from one end of the fuel cell.AboveCombusting in a storage container and the fuel reformerTheExposure to combustion gasesYouA method of operating a fuel cell, wherein the temperature of the fuel reformerPartWhen the temperature is lower than the partial oxidation start temperatureThe aboveCombustion heat from combustion gasTo heat the fuel reformer and / or to store the heating device in the storage container andBy heat from the heating deviceAboveHeating the fuel reformer,The temperature of the fuel reformer isAbove the partial oxidation reaction start temperatureAnd the fuel cellsteady stateNotIn some cases, the reaction heat of the partial oxidation reactionAboveCombustion heat by combustion gas and endotherm of steam reforming reactionAnd by the aboveHeating the fuel reformerThePartial oxidation reforming and steam reformingConduct,The fuel cellFor steady state,AboveBy the heat of combustion from the combustion gasAboveHeating the fuel reformerTheIt is characterized by performing steam reforming.
[0051]
At the start of the fuel cell, the temperature of the fuel reformer is room temperature, so the catalyst is heated in the same manner as described above from room temperature to the partial oxidation reaction start temperature.
[0052]
  Unlike the above from the partial oxidation reaction start temperatureTheWhile controlling the temperature of the fuel reformer by autothermal methodUntil the fuel cell reaches a steady stateBy heating, the durability of the fuel reformer is reduced and destroyed and the performance of the reforming catalyst is deteriorated due to excessive heat generation, which is a concern in the case of the partial oxidation reaction alone. After reaching the steady state, the same as above.In any of the fuel cell operating methods described above, the heating device can be stopped after the temperature of the fuel reformer reaches the partial oxidation reaction start temperature.
[0053]
  Further, the fuel cell operating method of the present invention includes a plurality of fuel cells and a fuel reformer in a storage container.WhenThe fuel gas from one end of the fuel cell.AboveCombusting in a storage container and the fuel reformerTheExposure to combustion gasesYouA method of operating a fuel cell, wherein the temperature of the fuel reformerWaterSteam condensesDoWarmDegreein case of,AboveCombustion heat from combustion gasTo heat the fuel reformer and / or to store the heating device in the storage container andBy heat from the heating deviceAboveHeating the fuel reformer,AboveFuel reformer temperatureWaterTemperature at which steam does not condenseIn degreesAhPartPartial oxidation reaction and steam reforming reactionWhenIf the temperature is lower than the combined reforming start temperatureThe aboveCombustion heat from combustion gasAnd / or saidBy heat from the heating deviceAboveWhile heating the fuel reformerAboveSupplying steam to the fuel reformer,AboveFuel reformer temperatureWaterTemperature at which steam does not condenseIn degreesAhPartPartial oxidation reaction and steam reforming reactionWhenAbove the combined reforming start temperature ofAnd the fuel cellsteady stateNotin case of,AboveCombustion heat from combustion gas, orAboveOf heat and partial oxidation reaction from the heating devicereactionheatWhenEndotherm of steam reforming reactionAnd by the aboveHeating the fuel reformerThePartial oxidation reforming and steam reformingWhenTheConduct,The fuel cellFor steady state,AboveBy the heat of combustion from the combustion gasAboveHeating the fuel reformerTheIt is characterized by performing steam reforming.
[0054]
  At the start of the fuel cell, the temperature of the fuel reformer is at room temperature, so the water is less than the combined reform start temperature for partial oxidation reaction and steam reforming reaction from room temperature, and water is condensed.DoWarmIn degreesThe fuel reformer is heated by the combustion heat from the combustion gas or the heat from the heating device.
[0055]
  Furthermore, the temperature at which water does not condenseIn degreesThe reformed gas composition generated immediately after the combined reforming reaction of the partial oxidation reaction and the steam reforming reaction is started by adding steam in advance at a temperature lower than the combined reforming start temperature of the partial oxidation reaction and the steam reforming reaction. In this case, the influence of carbon deposition on the fuel cell can be suppressed, and the fuel reforming temperature can be controlled by controlling the water vapor amount and the oxygen-containing gas amount. After the start of the combined reforming reaction of the partial oxidation reaction and the steam reforming reaction,Fuel cellStationaryNot in stateIn some cases, the heat of combustion from the combustion gas or the heat from the heating device and the partial oxidation reactionreactionheatWhenEndotherm of steam reforming reactionAnd byThe fuel reformer temperature can be controlled by heating the fuel reformer and controlling the amount of water vapor and the amount of oxygen-containing gas as described above.
[0056]
Note that the temperature at which water does not condense means, for example, a temperature at which water droplets caused by water vapor are not generated on the wall surface of the flow channel even when water vapor is circulated through the flow channel.
[0057]
Further, in a steady state where the fuel cell is sufficiently heated and can generate power, the fuel reforming is performed by switching to the steam reforming method.
[0058]
  In addition, the fuel cell operation method of the present invention includes a fuel reformer.ReformWhen the method is switched, the supply amount of fuel gas, oxygen-containing gas, and water vapor is changed.
[0059]
  ExampleFor example, when switching from the partial oxidation reforming method to the autothermal method, based on the number of moles of oxygen atoms in the reformed gas from the ratio of the fuel gas and the oxygen-containing gas supplied by the partial oxidation reforming method, Each supply amount is gradually changed so that the sum of the number of moles of oxygen atoms in the oxygen-containing gas supplied when switching to the autothermal method becomes equal to the number of moles of oxygen atoms in water vapor.
[0060]
After that, when performing the autothermal method, the operation is performed by gradually changing the supply amounts of the fuel gas, the oxygen-containing gas, and the water vapor so that the optimum conditions are obtained according to the state of the fuel cell and the fuel reformer. .
[0061]
Furthermore, when switching from the autothermal method to the steam reforming method, the fuel gas and oxygen-containing gas supplied by the autothermal method are based on the ratio of the fuel gas and steam required by the steam reforming method. The operation is performed by gradually changing each supply amount of water vapor.
[0062]
By switching as described above, it is possible to suppress an abrupt temperature change due to rapid start-up, to perform operation under optimum conditions according to the state of the fuel cell and the fuel reformer, and to realize high power generation efficiency.
[0063]
DETAILED DESCRIPTION OF THE INVENTION
  1 and 2 show the fuel cell of the present invention.Cell in the operation method ofThe code | symbol 1 has shown the storage container which has a heat insulation structure.
[0064]
The storage container 1 includes a frame body (not shown) made of a heat-resistant metal and a heat insulating material (not shown) provided on the inner surface of the frame body.
[0065]
The storage container 1 stores a plurality of fuel cell stacks 7 in which a fuel reformer 3 and an auxiliary heat source (heating device not shown) and a plurality of fuel cells 5 are assembled. The lower end portion of the fuel battery cell 5 is supported and fixed to the upper lid 10 of the fuel gas tank 8 that also serves as a support for the fuel battery cell 5.
[0066]
For example, as shown in FIG. 2, the fuel cell stack 7 includes a plurality of fuel cells 5 each having a fuel gas passage 11 formed therein, arranged in two rows, and two rows of outermost fuel cells arranged adjacent to each other. The electrodes of the cells 5 are connected by the conductive member 12, whereby a plurality of fuel cells 5 arranged in two rows are electrically connected in series. The fuel cells 5 are connected to each other by a conductive current collecting member 14.
[0067]
In FIG. 2, the detailed structure of the fuel cell 5 is omitted. Moreover, the fuel cell stack was described as two rows.
[0068]
  FIG. 3 specifically illustrates the structure of the fuel cell 5 and the fuel cell stack 7. The fuel cell 5 has, for example, a flat cross section and an elliptic cylinder shape as a whole. InsideLengthA plurality of fuel gas passages 11 are formed in the direction. This fuel cell 5 has a shape that is long in the direction of the fuel gas passage 11,LengthThe length of the direction isLengthIt is formed longer than the width direction length orthogonal to the direction.
[0069]
The fuel cell 5 has a flat cross section, and a dense solid electrolyte 5b, porous conductivity on the outer surface of a fuel-side electrode 5a mainly composed of a porous metal having an elliptical columnar shape as a whole. The oxygen-side electrode 5c made of ceramics is sequentially laminated, and an interconnector 5d is formed on the outer surface of the fuel-side electrode 5a opposite to the oxygen-side electrode 5c. The fuel-side electrode 5a serves as a support. .
[0070]
A current collecting member 14 made of metal felt and / or a metal plate is interposed between one fuel cell 5 and the other fuel cell 5, and the fuel side electrode 5 a of one fuel cell 5 is connected to the fuel cell 5. A fuel cell stack 7 is configured by being electrically connected to the oxygen side electrode 5c of the other fuel cell 5 via an interconnector 5d provided on the fuel side electrode 5a and a current collecting member 14.
[0071]
In the fuel cell stack 7, a portion where the fuel side electrode 5a, the solid electrolyte 5b, and the oxygen side electrode 5c are superimposed is a portion that generates power.
[0072]
A portion where the fuel side electrode 5a, the solid electrolyte 5b, and the oxygen side electrode 5c overlap is present at the center of the power generation chamber 16 as shown in FIG. 1, and the oxygen side electrode 5c is located at both ends of the fuel cell 5. Is not formed, and both end portions of the fuel cell 5 do not contribute to power generation. The lower end portion of the fuel cell 5 in which the oxygen side electrode 5 c is not formed is supported by the upper lid 10 of the fuel gas tank 8. The dense solid electrolyte 5b prevents gas mixing inside and outside the solid electrolyte 5b in the power generation chamber 16.
[0073]
In such a fuel cell, in order to generate electric power, it is necessary to supply an oxygen-containing gas to the outside of the fuel cell 5. Therefore, an oxygen-containing gas pipe 18 is connected to the storage container 1. In addition, it is necessary to supply a hydrogen-containing gas to the inside of the fuel battery cell 5. For this reason, the storage container 1 is connected to a gas introduction pipe 28 for supplying a gas necessary for the reforming reaction. The reformed gas introduced from the gas introduction pipe 28 is introduced into the fuel reformer 3, reformed into a gas containing hydrogen gas, and passes through the reformed gas supply pipe 22 and the gas tank chamber 24. Introduced into the fuel cell 5, the power generation unit of the fuel cell 5 causes an electrochemical reaction with the oxygen-containing gas described above, thereby contributing to power generation.
[0074]
Excess fuel gas that has not been used for power generation is mixed with the oxygen-containing gas and burned in the combustion section 25 above the fuel cell 5. The combustion heat is used to heat the fuel reformer 3 provided above the fuel cell 5, and the combustion gas is supplied from the exhaust gas pipe 26 provided on the upper side of the storage container 1 to the fuel cell. Exhausted to the outside.
[0075]
The fuel reformer 3 is formed of, for example, a heat-resistant metal, has a structure as shown in FIGS. 4A and 4B, and has a flow as shown in FIG. A reformed gas supply pipe 28a for supplying raw fuel such as natural gas subjected to desulfurization treatment to the fuel reformer 3, an oxygen-containing gas supply pipe 28b for supplying oxygen-containing gas, and water vapor or water are supplied. A water supply pipe 28c is connected.
[0076]
4A and 4B are different in structure, but both show the fuel reformer 3 of the present invention. The fuel reformer 3 may have a layer structure, for example, as shown in FIG. 4 (a), or may have a nested structure, as shown in FIG. 4 (b).
[0077]
The three pipes may be directly connected to the fuel reformer 3, but the reformed gas, the oxygen-containing gas, and water vapor or water can be simultaneously introduced into the fuel reformer 3. Is important, and a multiple pipe structure may be used, or three pipes may be connected to form one pipe and connected.
[0078]
The fuel reformer 3 includes, for example, a water vapor generating and mixing unit 30 that integrates a water vapor generating unit 30a that generates water vapor and a gas mixing unit 30b that mixes gas when water is directly supplied, and a gas to be reformed. The gas is composed of a flow path 32, a reforming section 34, and a reformed gas flow path 36, and various gases introduced into the fuel reformer 3 pass through these flow paths and are then supplied to the reformed gas supply pipe 22. Led.
[0079]
The steam generation and mixing unit 30 is, for example, Al.₂O₃By filling a spherical body composed of a heat-resistant member that does not have catalytic ability, a turbulent flow is generated when gas flows through the gap between the spherical bodies, and a plurality of gas species are sufficiently mixed, By using a spherical body having a large heat capacity and heat transfer area, water vapor can be generated smoothly and the reformed gas can be preheated.
[0080]
Further, the steam generation / mixing unit 30 is filled with a noble metal catalyst 34a that is unlikely to cause carbon deposition, and a part of the functions of the steam generation / mixing unit 30 and the reforming unit 34 is shared.
[0081]
In the reforming section 34, the noble metal catalyst 34a and the base metal catalyst 34b are mixed, the noble metal catalyst 34a is unevenly distributed near the inlet from the reformed gas flow path 32, and the base metal catalyst 34b is otherwise present. Filled. The ratio of the noble metal catalyst 34 a is preferably about 5 to 30% with respect to the total volume of the reforming section 34.
[0082]
In order to improve the startability in these mixed states, it is preferable that the noble metal catalyst 34a is unevenly distributed on the inlet side of the reforming section 34 that first contacts with the reformed gas. It may be distributed.
[0083]
Base metal catalyst 34b is a spherical Al₂O₃The noble metal catalyst 34a is also spherical Al.₂O₃It is preferable that Ru is supported on the surface of each of which a third component such as Mg may be added.
[0084]
The reforming section 34 may be a single noble metal catalyst 34a or a single base metal catalyst 34b.
[0085]
By forming the reformed gas flow path 36 along the reforming section 34, heat exchange is performed between the reforming catalyst inlet vicinity and the reformed gas. By arranging a baffle plate or the like in the reformed gas channel 36 to increase the length of the channel and increase the heat transfer area from the reforming unit 34, the heat exchange efficiency is further increased.
[0086]
In addition, the reforming section 34 is formed at the highest temperature position in the fuel reformer 3, and the reformed gas flow path 36 is formed along the reforming section 34 to perform heat exchange with the reforming section 34. By forming the reformed gas channel 32 along the reformed gas channel 36, heat exchange occurs with the reformed gas, and the reformed gas is preheated.
[0087]
The gas flow at this time is preferably such that the gas to be reformed and the reformed gas flowing in the fuel reformer 3 face each other.
[0088]
In addition, by introducing a reformed gas at room temperature into the high temperature reforming section 34 that performs the reforming reaction, the catalyst temperature decreases and the reforming ability decreases. By forming the to-be-reformed gas flow path 32 along the line 34, heat exchange is performed between the reforming unit 34 and the to-be-reformed gas to preheat the to-be-reformed gas.
[0089]
Thereby, the temperature difference between the catalyst temperature and the reformed gas temperature is reduced, and the decrease in the catalyst temperature can be suppressed. Further, the object to be heat exchanged by the reformed gas may be a reformed gas.
[0090]
As described above, it is not always necessary to form the reformed gas flow path 32 and the reformed gas flow path 36 along the reforming portion 34, and either one or no gas flow path is formed, and the fuel is not formed. The reformer 3 may be composed of only the reforming unit 34.
[0091]
The reformed gas supply pipe 22 connected to the fuel gas tank 8 may be connected to a raw fuel supply pipe 41 that is branched in the middle and introduced into the desulfurizer 40. In this way, by partially circulating the reformed gas, it is possible to supply a trace amount of hydrogen necessary for hydrodesulfurization treatment in which the organic sulfur component is converted to hydrogen sulfide. As a method for adjusting the circulation rate, a flow meter may be used, but a method using an ejector is preferable.
[0092]
Similarly, by connecting the reformed gas supply pipe 22 to the to-be-reformed gas supply pipe 28a, the amount of steam or water supplied at the same time can be reduced, so that the large heat of vaporization accompanying the generation of steam can be reduced. , Improve thermal efficiency.
[0093]
The reformed gas that has passed through the fuel reformer 3 having such a structure is reformed into a hydrogen-containing gas, and the reformed gas generated in the reforming section 34 passes through the reformed gas flow path 36. It passes through and is discharged from the reformed gas supply pipe 22.
[0094]
The reformed gas supply pipe 22 is connected to the fuel gas tank 8, and the reformed gas is supplied to the fuel battery cell 5 via the fuel gas tank 8.
[0095]
The reformed gas can be used as fuel for an auxiliary heat source (heating device) described later by branching the reformed gas supply pipe 22 in the middle and distributing a part of the reformed gas.
[0096]
Similarly, by connecting to the reformed gas supply pipe 28a for supplying the reformed gas to the fuel reformer 3, the amount of oxygen-containing gas, water vapor or water supplied at the same time can be reduced.
[0097]
The reformed gas supply pipe 22 may be connected to the number of the fuel reformer 3 and the fuel cell stack 7, but may be branched by the number of the fuel cell stacks 7 in the middle. The shape, connection method, quantity, etc. of the supply pipe 22 are not particularly limited.
[0098]
A gas passage (not shown) is formed in the upper cover 10 of the fuel gas tank 8 to which the reformed gas is supplied, and this gas passage communicates with the fuel gas passage 11 of the fuel cell 5. It passes through the gas passage, the fuel gas passage 11 of the fuel battery cell 5 through the quality gas supply pipe 22 and the fuel gas tank chamber 24, and is introduced from the upper end of the fuel battery cell 5 into the combustion unit 25. An ignition device (not shown) is disposed in the combustion unit 25, and is ignited using this to discharge oxygen from the oxygen-containing gas pipe 18 and the upper end of the fuel cell 5. In addition, the surplus gas that was not used for power generation burns and diffuses.
[0099]
The fuel cell configured as described above is operated as follows, for example.
[0100]
At the start of the fuel cell, the temperature of the fuel reformer 3 is normal temperature. Therefore, from the normal temperature to the partial oxidation reaction start temperature, the reformed gas introduced into the fuel cell 5 via the fuel reformer 3 The reformed gas mixed with the oxygen-containing gas is combusted in the combustion section 25 near one end of the fuel battery cell 5, and the fuel reformer 3 is heated to the partial oxidation reaction start temperature.
[0101]
At this time, even if the fuel cell 5 itself is heated by the combustion and the reforming reaction starts inside the fuel cell 5, carbon deposition on the fuel cell 5 is caused by mixing the oxygen-containing gas. Can be prevented.
[0102]
O at this time₂/ C must be greater than 0 and less than or equal to 1;₂When / C is small, carbon deposition is likely to occur.₂It is desirable to control so that /C=0.4-1.
[0103]
Further, an auxiliary heat source (heating device) may be used instead of combustion, or both may be used together and heated to the same temperature.
[0104]
When the auxiliary heat source (heating device) is a burner, a part of the reformed gas may be used as the fuel, or the raw fuel or the gas to be reformed may be used.
[0105]
After reaching the partial oxidation reaction start temperature, the gas to be reformed, which is a mixture of the gas to be reformed and the oxygen-containing gas, starts the partial oxidation reaction. The vessel 3 is heated up.
[0106]
When the auxiliary heat source (heating device) is used in this state, the heating from the auxiliary heat source (heating device) may be stopped.
[0107]
However, the heating by combustion from one end of the fuel cell 5 is indispensable for raising the temperature of the fuel cell, maintaining the temperature, and further maintaining the temperature of the fuel reformer 3 in a steady state, so that the combustion is continued. There is a need to.
[0108]
Therefore, in this temperature range, the fuel reformer 3 is heated by the reaction heat and combustion heat of the partial oxidation reaction.
[0109]
  After reaching the steam reforming temperature, the reaction heat of the partial oxidation reactionWhenCombustion heatWhenIn order to prevent deterioration of the fuel reformer 3 due to excessive heating, destruction, and degradation of the performance of the reforming catalyst,,Oxygen-containing gasWhen,water vaporWhenBy mixing the partial oxidation reaction and the steam reforming reaction, which is an endothermic reaction.UseThe temperature of the fuel reformer 3 is controlled using the autothermal method.
[0110]
When switching from the partial oxidation reforming method to the autothermal method, the autothermal method is based on the number of moles of oxygen atoms in the reformed gas based on the ratio of the fuel gas and oxygen-containing gas supplied by the partial oxidation reforming method. Each supply amount is gradually changed so that the sum of the number of moles of oxygen atoms in the oxygen-containing gas supplied when switching to the method and the number of moles of oxygen atoms in water vapor are equal.
[0111]
By performing the switching in this way, the reformed gas can be controlled. When the autothermal method is performed, the fuel gas, the oxygen-containing gas, and the water vapor are supplied in various amounts so that the optimum conditions are obtained according to the conditions of the fuel cell 5 and the fuel reformer 3. I do.
[0112]
When heating is required, the oxygen-containing gas ratio is increased and the water vapor ratio is decreased, so that the total amount of heat related to the reforming reaction is exothermic. By increasing the ratio, the reaction related to the reforming reaction is made an endothermic reaction, and temperature control is performed.
[0113]
After the fuel cell 5 is sufficiently heated and reaches a steady state where power generation is possible, the fuel reforming is performed by switching to the steam reforming method with the largest amount of hydrogen generation and the highest power generation efficiency. In this temperature range, the heating source is only combustion heat.
[0114]
In addition, when switching from the autothermal method to the steam reforming method, the fuel gas supplied by the autothermal method based on the ratio (S / C) of the fuel gas and steam required by the steam reforming method. The operation is performed by gradually changing the supply amounts of oxygen-containing gas and water vapor. The S / C at this time is preferably in the range of 1.5 to 3.5. By setting S / C to 1.5 or more from this range, carbon deposition can be suppressed, and performance deterioration and destruction of the reforming catalyst and the fuel battery cell 5 can be prevented. Moreover, by setting it as 3.5 or less, a water vapor partial pressure can be made appropriate and the fall of electric power generation performance can be prevented.
[0115]
In addition, fuel gas and oxygen-containing gas and / or steam are circulated at temperatures from room temperature to the start of partial oxidation reaction or steam reforming reaction, or combination reforming reaction using partial oxidation reaction and steam reforming reaction in combination. Thus, even if the gas supplied to the fuel cell via the fuel reformer is reformed inside the fuel cell heated to a temperature higher than that of the fuel reformer, the gas is supplied to the fuel cell body. The effects of carbon deposition and the like can be reduced.
[0116]
  In addition, from normal temperatures, fuel gas and oxygen-containing gasWhenThe temperature at which water does not condenseIn degreesPartial oxidation reaction and steam reforming reactionWhenCombined reforming reactionButIt is preferable to add water vapor at a temperature until the start. As a result, even in a state where the conversion rate is low immediately after reaching the temperature at which the combined reforming reaction starts, the gas composition generated by reforming is assumed to be inside the fuel cell heated to a higher temperature than the fuel reformer. Even if it is modified, the influence of carbon deposition or the like on the fuel cell can be reduced. In addition, it is desirable to add water vapor | steam beforehand by the combined reform start temperature so that S / C of the gas composition produced | generated by modification | reformation may exist in the range of 1.5-3.5.
[0117]
O at this time₂/ C is desirably controlled to 0.4 to 1 in order to suppress carbon deposition, and the amount of steam S / C added by the combined reforming reaction start temperature ensures the heat amount and the steam partial pressure is appropriate. In order to achieve this, it is desirable to control it to be within 3.
[0118]
By switching in this way, carbon deposition on the reforming catalyst and the fuel cell 5 is surely suppressed, and a rapid temperature change due to rapid start-up is further suppressed, so that the fuel cell and the fuel reformer 3 In addition to being able to operate under optimal conditions according to conditions, high power generation efficiency can be realized.
[0119]
【The invention's effect】
  Fuel cell of the present inventionDriving methodAccording toThe fuel cell can be activated quickly and can be operated with high power generation efficiency.
[Brief description of the drawings]
FIG. 1 shows a fuel cell of the present invention.Example of a fuel cell in the operation methodIt is a schematic sectional drawing which shows.
FIG. 2 is a schematic cross-sectional view of FIG.
FIG. 3 is a cross-sectional view for explaining the fuel cell stack of FIG. 1;
4 is a cross-sectional view for explaining the fuel reformer of FIG. 1. FIG.
FIG. 5 is a schematic view for explaining the fuel reformer of FIG. 4;
[Explanation of symbols]
1 ... Storage container
3 ... Fuel reformer
5 ... Fuel cell
22 ... Reformed gas supply pipe
28a ... Reformed gas supply pipe
30 ... Steam generation and mixing section
32 ... Reformed gas flow path
34 ... reforming section
36 ... Reformed gas flow path

Claims (6)

Housing accommodating a fuel reformer plurality of fuel cells in the container, along with burning fuel gas from one end of the fuel cell in the storage container, the combustion gas from the fuel reformer a method of operating a曝to the fuel cell, when the temperature of the fuel reformer is less than parts partial oxidation reaction starting temperature, heating the fuel reformer by combustion heat by the combustion gases, and / or the addition to accommodating the heating device storing container heating the fuel reformer by the heat from the heating device, the fuel reformer temperature is lower than the steam reformable temperature partial oxidation reaction start temperature or more in the case performs partial oxidation reforming by heating the fuel reformer by combustion heat of the combustion gas and reaction heat of the partial oxidation reaction, the temperature of the fuel reformer steam reformable temperature or higher and the fuel cell steady state If not, perform the partial oxidation reforming and steam reforming to heat said fuel reformer by the endothermic heat of combustion and steam reforming reaction by reaction heat with the combustion gas of the partial oxidation reaction, the fuel If the battery is in steady state, the method of operating a fuel cell which is characterized in that the steam reforming by heating the fuel reformer I by the combustion heat by the combustion gases. Housing accommodating a fuel reformer plurality of fuel cells in the container, along with burning fuel gas from one end of the fuel cell in the storage container, the combustion gas from the fuel reformer a method of operating a曝to the fuel cell, when the temperature of the fuel reformer is less than parts partial oxidation reaction starting temperature, heating the fuel reformer by combustion heat by the combustion gases, and / or the addition to accommodating the heating device storing container heating the fuel reformer by the heat from the heating device, in the fuel temperature of the reformer is the partial oxidation reaction start temperature or higher and the fuel cell steady state If not performs partial oxidation reforming by heating the fuel reformer by combustion heat of the combustion gas and reaction heat of the partial oxidation reaction, when the fuel cell is in a steady state, the combustion gas Tsu by the combustion heat generated by The method of operating a fuel cell which is characterized in that the steam reforming by heating the fuel reformer. Housing accommodating a fuel reformer plurality of fuel cells in the container, along with burning fuel gas from one end of the fuel cell in the storage container, the combustion gas from the fuel reformer a method of operating a曝to the fuel cell, when the temperature of the fuel reformer is less than parts partial oxidation reaction starting temperature, heating the fuel reformer by combustion heat by the combustion gases, and / or the addition to accommodating the heating device storing container heating the fuel reformer by the heat from the heating device, in the fuel temperature of the reformer is the partial oxidation reaction start temperature or higher and the fuel cell steady state If not performs a partial oxidation reforming and steam reforming to heat said fuel reformer by the endothermic heat of combustion and steam reforming reaction by reaction heat with the combustion gas of the partial oxidation reaction, the fuel when the battery is in a steady state The method of operating a fuel cell which is characterized in that the steam reforming by heating the fuel reformer by combustion heat by the combustion gases. Housing accommodating a fuel reformer plurality of fuel cells in the container, along with burning fuel gas from one end of the fuel cell in the storage container, the combustion gas from the fuel reformer a method of operating a曝to the fuel cell, when the temperature of the temperature of the fuel reformer is condensed water vapor heats the fuel reformer by combustion heat by the combustion gases, and / or said housing while accommodating the heating device within the container by heating the fuel reformer by the heat from the heating device, the fuel temperature of the reformer is a temperature which does not condense water vapor part partial oxidation reaction steam to the fuel reformer with the in the case of combination reforming start temperature below the steam reforming reaction, which heats the fuel reformer by the heat from combustion heat and / or the heating device by the combustion gases supply, the fuel reformer Of if the temperature is not a combination reformer starting temperature or more and the fuel cell steady state with a temperature which does not condense water vapor part partial oxidation reaction and steam reforming reaction, combustion heat by the combustion gases, or perform a partial oxidation reforming and steam reforming to heat said fuel reformer by the heat and the partial oxidation reaction heat and the steam reforming reaction of the reaction heat absorption from the heating device, the fuel cell is steady state in the case of a method of operating a fuel cell which is characterized in that the steam reforming by heating the fuel reformer by combustion heat by the combustion gases. The method of operating a fuel cell according to any one of claims 1 to 3, wherein the heating device is stopped after the temperature of the fuel reformer reaches a partial oxidation reaction start temperature. When you change the reforming reaction of the fuel reformer, the fuel gas, the oxygen-containing gas, the fuel according to any one of claims 1 to 5, characterized in that changing the supply amount of water vapor Battery operation method.

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