JP2016100183A - Fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery system that can perform more proper temperature control of a hydrodesulfurizer as compared with a prior art when the hydrodesulfurizer is heated by exhaust gas.SOLUTION: A fuel battery system has a fuel battery for generating power by using air and fuel obtained by reforming raw material, a hydrodesulfurizer for removing sulfur components in raw material, a first heat-exchanger which has an air passage through which air flows and a first exhaust gas passage through which exhaust gas flows, and heat-exchanges the air and the exhaust gas, a second heat-exchanger which has an air passage and a second exhaust gas passage through which exhaust gas flows, and heat-exchanges the air and the exhaust gas, and a heater for heating the hydrodesulfurizer by using exhaust gas. The exhaust gas flows through the first exhaust gas passage of the first heat-exchanger, the heater and the second exhaust gas passage of the second heat-exchanger in this order, the air flows through the air passage of the second heat-exchanger, the air passage of the first heat-exchanger and the fuel battery in this order, and the first heat-exchanger and the second heat-exchanger are configured integrally with each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system.

  In a fuel cell system using hydrocarbons as a raw material, for example, reforming of the raw material using steam is performed. A reforming catalyst is used to promote this steam reforming, but the raw material contains a sulfur compound as an odorant. This sulfur compound may deteriorate the reforming catalyst.

  Therefore, in order to prevent the reforming catalyst from deteriorating, a desulfurization apparatus that reduces the sulfur compound contained in the raw material is used.

  As a desulfurization device, for example, a sulfur compound is reacted with hydrogen on a catalyst (for example, Ni-Mo system, Co-Mo system, etc.) to convert it into hydrogen sulfide, and the hydrogen sulfide is removed by taking it into, for example, zinc oxide. Hydrodesulfurizers that perform hydrodesulfurization are known, and various countermeasures have been proposed.

  For example, a hydrodesulfurizer requires hydrogen when performing a hydrogenation reaction, but the raw material usually does not contain hydrogen. Therefore, a solid oxide fuel cell system having a configuration for supplying a hydrogen-containing recycle gas to a hydrodesulfurizer has been proposed (for example, Patent Documents 1 and 2). Specifically, as shown in FIG. 6, in the fuel cell system 1 of Patent Document 1, a part of the hydrogen-containing gas that has passed through the reformer 110 passes through the recycle gas supply path 113 on the upstream side of the booster 111. It is configured to be returned to. The hydrogen-containing gas is boosted by the boosting means 111 and supplied to the hydrodesulfurizer 102. As shown in FIG. 7, the fuel cell system of Patent Document 2 is a desulfurization that includes water vapor when supplying the water mixed in the mixer 220 and the raw fuel gas after desulfurization from the evaporator 226 to the reformer 206. A part of the subsequent raw fuel gas is returned to the raw fuel gas supply path 216 via the branch return flow path 242. A hydrocarbon reforming catalyst is provided in the double pipe 244 of the branch return channel 242, whereby the hydrogen-containing gas obtained by reforming the hydrocarbon is returned to the upstream side of the booster 217. ing. The hydrogen-containing gas is boosted by the booster 217 and supplied to the hydrodesulfurizer 204.

  Further, in Patent Document 3, since the performance of the hydrodesulfurizer varies depending on the ambient temperature, a configuration is proposed in which the hydrodesulfurizer is heated using high-temperature exhaust gas generated during power generation for those used at high temperatures. ing.

  In Patent Document 4, in a fuel cell system such as SOFC or PEFC, when a hydrodesulfurizer that removes sulfur components in a raw material is heated by exhaust gas discharged from a power generation module, the temperature of the exhaust gas depends on the amount of power generation. There has been proposed a configuration intended to suppress the excessive temperature rise of the hydrodesulfurizer even when it rises, to improve the desulfurization efficiency of the hydrodesulfurization agent, and to extend the service life. Specifically, as shown in FIG. 8, the fuel cell system of Patent Document 4 includes a cooler that includes exhaust gas before flowing into the hydrodesulfurizer 6 and air into which a part of power generation air is diverted. 7 is configured to exchange heat. Thereby, the excessive temperature rise of the hydrodesulfurizer is suppressed by reducing the temperature of the exhaust gas flowing into the hydrodesulfurizer 6 to a desired temperature range.

JP 2011-216308 A Japanese Patent No. 4911927 JP 2006-309982 A JP 2012-155978 PR

  However, in the conventional example, adequate temperature control of the hydrodesulfurizer when the hydrodesulfurizer is heated with exhaust gas has not been sufficiently studied.

  One aspect of the present invention has been made in view of such circumstances, and in the case where the hydrodesulfurizer is heated with exhaust gas, the temperature of the hydrodesulfurizer is controlled more appropriately than in the past. A fuel cell system is provided.

  The fuel cell system of one embodiment of the present invention includes a fuel cell that generates power using fuel and air obtained by reforming a raw material, a hydrodesulfurizer that removes sulfur components in the raw material, and the air flows. A first heat exchanger for exchanging heat between the air and the exhaust gas, and a second exhaust gas through which the air path and the exhaust gas flow. A second heat exchanger for exchanging heat between the air and the exhaust gas, and a heater for heating the hydrodesulfurizer using the exhaust gas, wherein the exhaust gas is the first heat The first exhaust gas path of the exchanger, the heater, and the second exhaust gas path of the second heat exchanger flow in this order, and the air is the air path of the second heat exchanger, the first heat exchange. The air path of the vessel and the fuel cell Flow, the first heat exchanger and the second heat exchanger, but are formed integrally.

  According to one aspect of the present invention, when a hydrodesulfurizer is heated with exhaust gas, a fuel cell system capable of performing appropriate temperature control of the hydrodesulfurizer is obtained compared to the conventional case.

FIG. 1 is a diagram illustrating an example of a fuel cell system according to the first embodiment. FIG. 2 is a diagram illustrating an example of a heat exchanger of the fuel cell system according to the first example of the first embodiment. FIG. 3 is a diagram illustrating an example of a heat exchanger of the fuel cell system according to the second example of the first embodiment. FIG. 4 is a diagram illustrating an example of a fuel cell system according to the second embodiment. FIG. 5A is a diagram illustrating an example of a heat exchanger of the fuel cell system according to the third embodiment. FIG. 5B is a diagram illustrating an example of a heat exchanger of the fuel cell system according to the third embodiment. FIG. 6 is a diagram showing an example of a conventional fuel cell system. FIG. 7 is a diagram showing an example of a conventional fuel cell system. FIG. 8 is a diagram showing an example of a conventional fuel cell system. FIG. 9 is a diagram used for comparison with the configuration of the fuel cell system of the first embodiment.

(First embodiment)
The inventors diligently studied about appropriate temperature control of the hydrodesulfurizer when the hydrodesulfurizer is heated with exhaust gas, and obtained the following knowledge.

  Patent Document 1 and Patent Document 2 do not disclose specific means for controlling the temperature of the hydrodesulfurizer, and the hydrodesulfurization agent of the hydrodesulfurizer is stably adjusted to a temperature suitable for the hydrogenation reaction. It is difficult to control.

  In Patent Documents 3 and 4, there is a possibility that the configuration becomes complicated in order to perform appropriate temperature control of the hydrodesulfurizer. Furthermore, such temperature control may be difficult.

  Therefore, as shown in FIG. 9, heat exchange between the air for power generation to the fuel cell 1 and the exhaust gas that has passed through the hydrodesulfurizer 2 and heat exchange with the exhaust gas from the fuel cell 1 are performed. The fuel cell system 100 provided with the heat exchanger 5 which heat-exchanges with the air which passed the container 4 is proposed (Japanese Patent Application No. 2013-262387). The fuel cell system 100 of FIG. 9 can effectively use the heat quantity of the exhaust gas as compared with the prior art. Therefore, the power generation efficiency of the fuel cell system 100 can be improved, and the hydrodesulfurizer 2 can be stably controlled within an appropriate temperature range.

  However, the fuel cell system 100 of FIG. 9 requires various gas paths 6, 7, and 10 that connect the heat exchanger 4 and the heat exchanger 5. Therefore, since heat radiation of gas occurs in these paths 6, 7, and 10, the power generation efficiency of the fuel cell system 100 may be reduced.

  For example, when the heat exchanger 4 and the heat exchanger 5 are arranged away from the hydrodesulfurizer 2, heat release of the exhaust gas is likely to occur from the piping that forms the exhaust gas path. Thereby, the power generation efficiency of the fuel cell system 100 may be reduced.

  Further, when the heat exchanger 4 and the heat exchanger 5 are arranged away from the hydrodesulfurizer 2, heat radiation from the air is likely to occur due to the piping that forms the air path. That is, the air preheated by the heat exchanger 4 may dissipate in the middle of the air path connecting the heat exchanger 4 and the heat exchanger 5, and the power generation efficiency of the fuel cell system 100 may be reduced.

  Moreover, the fuel cell system 100 is increased in size by providing two heat exchangers separately. Then, the heat transfer area of the housing of the fuel cell system 100 increases, and the heat dissipation amount of the fuel cell system 100 increases. When the heat dissipation amount of the fuel cell system 100 increases, the power generation efficiency of the fuel cell system 100 may decrease.

  Further, when the amount of heat released from the piping or casing of the fuel cell system 100 increases, there is also a problem that it becomes difficult to balance the heat of the fuel cell system 100.

  Furthermore, the fuel cell system 100 of FIG. 9 has a difficulty in miniaturizing the fuel cell system 100 because the heat exchangers 4 and 5 are configured separately. In addition, the cost of the fuel cell system 100 tends to increase. For example, providing two heat exchangers separately increases the number of constituent members of the fuel cell system 100, increases the number of assembly steps, and increases the manufacturing cost. Further, the volume of the fuel cell system 100 increases and the fuel cell system 100 becomes larger.

  Accordingly, the inventors diligently studied the various problems related to the fuel cell system 100 of FIG. 9 and arrived at the idea of integrally configuring the two heat exchangers 4 and 5.

  That is, the fuel cell system of the first embodiment includes a fuel cell that generates power using fuel and air obtained by reforming a raw material, a hydrodesulfurizer that removes sulfur components in the raw material, and air that flows air. A first exhaust gas path through which the exhaust gas used for heating the path and the fuel cell flows, a first heat exchanger for exchanging heat between the air and the exhaust gas, a second exhaust gas path through which the air path and the exhaust gas flow, and an air And a second heat exchanger for exchanging heat with the exhaust gas, and a heater for heating the hydrodesulfurizer using the exhaust gas. The exhaust gas flows in this order through the first exhaust gas path of the first heat exchanger, the heater and the second exhaust gas path of the second heat exchanger, and the air flows through the air path of the second heat exchanger, the first heat exchanger. The air path and the fuel cell flow in this order, and the first heat exchanger and the second heat exchanger are integrally configured.

  The fuel cell may be a solid oxide fuel cell.

  With this configuration, when the hydrodesulfurizer is heated with exhaust gas, it is possible to control the temperature of the hydrodesulfurizer more appropriately than in the past.

  In addition, by integrally configuring the first heat exchanger and the second heat exchanger, the number of members connecting the first heat exchanger, the second heat exchanger, and the heater and the flow path length can be reduced. it can. Since the fuel cell system can be downsized by integrally configuring the first heat exchanger and the second heat exchanger, the heat transfer area of the fuel cell system housing can be reduced.

  As described above, the fuel cell system according to the present embodiment can suppress the heat radiation from the respective members as compared with the fuel cell system 100 of FIG. Therefore, the power generation efficiency of the fuel cell system can be improved. Furthermore, since heat dissipation of the fuel cell system can be suppressed, it becomes easy to achieve a heat balance of the fuel cell system.

  In addition, the number of members connecting the first heat exchanger, the second heat exchanger, and the heater and the flow path length can be reduced, and the manufacturing cost of the fuel cell system can be reduced by downsizing the fuel cell system.

  Hereinafter, specific examples of the first embodiment will be described with reference to the drawings. In the following, the same or corresponding components are denoted by the same reference numerals throughout all the drawings, and the description thereof is omitted.

[Device configuration]
FIG. 1 is a diagram illustrating an example of a fuel cell system according to the first embodiment.

  As shown in FIG. 1, the fuel cell system 100 includes a fuel cell 6, a reformer 4, a hydrodesulfurizer 3, a heater 8, an air path 10, a first exhaust gas path 20, The heat exchanger 5, the second exhaust gas path 21, and the second heat exchanger 13 are provided.

  The fuel cell 6 generates power using the fuel and air obtained by reforming the raw material. The fuel cell system 100 may include a reformer 4 that generates a hydrogen-containing gas by a reforming reaction using a charge. When the reformer 4 is not provided, a hydrogen-containing gas is generated by a reforming reaction in the fuel cell unit. As such an example, an internal reforming type solid oxide fuel cell can be mentioned.

  The fuel cell 6 may be any type. Examples of the fuel cell 6 include a polymer electrolyte fuel cell, a solid oxide fuel cell, and a phosphoric acid fuel cell.

  When the fuel cell 6 is a solid oxide fuel cell, the hydrodesulfurizer 3, the reformer 4, the fuel cell 6, the first heat exchanger 5, the heater 8, the second heat exchanger 13, etc. Alternatively, a heat insulating material (not shown) may be used and disposed in the housing of the fuel cell unit.

  The fuel cell 6 includes a fuel electrode to which fuel is supplied and an air electrode to which air is supplied, and a plurality of fuel cell single cells that generate power by performing a power generation reaction between the fuel electrode and the air electrode are connected in series. Connected to form a cell stack. In addition, the fuel cell 6 is good also as a structure which connected the cell stack further connected in series in parallel.

  When the fuel cell 6 is a solid oxide fuel cell, the fuel cell single cell constituting the fuel cell 6 is, for example, zirconia doped with yttria (YSZ), zirconia doped with yttrium or scandium, or a lanthanum gallate system. A single fuel cell cell having a solid electrolyte of the above can be used. For example, when the fuel cell unit cell includes YSZ, the power generation reaction of the fuel cell 6 is performed in a temperature range of about 600 to 900 ° C., depending on the thickness.

  In addition, a raw material contains the organic compound comprised from carbon and hydrogen at least, such as city gas and natural gas which have methane as a main component, and LPG.

  Further, the reforming reaction in the fuel cell system 100 (in this embodiment, the reforming reaction of the reformer 4) may take any form. Examples of the reforming reaction include a steam reforming reaction, an autothermal reaction, and a partial oxidation reaction. Although not shown in FIG. 1, equipment required for each reforming reaction is provided as appropriate. For example, if the reforming reaction is a steam reforming reaction, an evaporator that generates steam and a water supply unit that supplies water to the evaporator are provided. If the reforming reaction is an autothermal reaction, an air supply device for supplying air is further provided.

Examples of the reforming catalyst of the reformer 4 include a catalyst in which Ni 2 is impregnated on the surface of an Al ₂ O ₃ (alumina) sphere, and a catalyst in which ruthenium is applied to the surface of the Al ₂ O ₃ sphere. .

  Here, when the fuel cell system 100 is activated, the reformer 4 has insufficient heat energy to perform a steam reforming reaction that is an endothermic reaction. Therefore, when the fuel cell system 100 is started, the partial oxidation represented by the following formula (1) is performed using the air supplied to the reformer 4 without supplying water to the evaporator from the reformed water path. Reforming is performed, and reformed gas (hydrogen-containing gas) and carbon monoxide gas are generated.

CnHm + (n / 2) O ₂ → n · CO + (m / 2) H ₂ (n and m are arbitrary natural numbers)
... (1)

  These reformed gas and carbon monoxide gas are supplied to the solid oxide fuel cell 6 and used in the power generation reaction together with air in the fuel cell 6.

  Further, after the fuel cell system 100 is started, the temperature of the reformer 4 rises as the power generation of the fuel cell 6 proceeds. That is, the partial oxidation reforming reaction represented by the above formula (1) is an exothermic reaction, and the heat of exhaust gas from the combustion section (not shown) for burning off-gas of the fuel cell 6 and the radiant heat of the combustion section. As a result, the temperature of the reformer 4 rises. Then, when the temperature of the reformer 4 is raised to, for example, 400 ° C. or higher, the steam reforming reaction represented by the following formula (2) can be performed in parallel.

_{CnHm + n · H 2 O →} n · CO + (m / 2 + n) H 2 (n, m is an arbitrary natural number)
... (2)

  The steam reforming reaction has a larger amount of hydrogen that can be generated from the same amount of hydrocarbon (CnHm) than the partial oxidation reforming reaction. Therefore, the amount of hydrogen in the reformed gas that can be used for the power generation reaction of the fuel cell 6 increases. That is, the reforming gas can be generated more efficiently in the steam reforming reaction than in the partial oxidation reforming reaction.

  On the other hand, the steam reforming reaction is an endothermic reaction. The reforming reaction needs to proceed. When the temperature of the reformer 4 is, for example, 600 ° C. or higher, the amount of heat necessary for the steam reforming reaction can be supplemented only by the heat of the exhaust gas and the radiant heat of the combustion section. The reaction is carried out only by steam reforming.

  The hydrodesulfurizer 3 removes sulfur components in the raw material. The raw material from which sulfur components such as sulfur compounds are removed is sent to the reformer 4. The hydrodesulfurizer 3 is filled with a hydrodesulfurizing agent. As the hydrodesulfurization agent, for example, a CuZn-based catalyst having both a function of converting a sulfur compound into hydrogen sulfide and a function of adsorbing hydrogen sulfide is used. The hydrodesulfurization agent is not limited to this example, but is a NiMo-based catalyst or CoMo-based catalyst that converts a sulfur compound in a raw material into hydrogen sulfide, and a sulfur adsorption that is disposed downstream thereof to adsorb and remove hydrogen sulfide. You may comprise with the ZnO type catalyst which is an agent, or a CuZn type catalyst.

  In addition, a part of the reformed gas sent to the fuel cell 6 may be supplied to the raw material before flowing into the hydrodesulfurizer 3 as hydrogen for hydrogenation reaction through a recycle path (not shown).

  For example, a path from the reformer 4 to the fuel cell 6 may be branched in the middle (branch portion), and a recycle path for returning a part of the reformed gas from the reformer 4 to the raw material may be provided. Thereby, it becomes possible to add hydrogen to the raw material supplied to the hydrodesulfurizer 3, and the hydrodesulfurizer 3 can perform the above-mentioned hydrodesulfurization using this hydrogen.

  Note that a decompression unit may be provided in the vicinity of a branch portion between the path from the reformer 4 to the fuel cell 6 and the recycling path and on the recycling path. The decompression unit adjusts the flow rate of the reformed gas flowing in the recycling path, and is configured by, for example, a capillary tube. That is, the decompression unit is configured such that the reformed gas flows through the recycling path by a desired flow rate by narrowing the flow path with a capillary tube or the like and increasing the pressure loss. Moreover, you may provide a condenser in the middle of this recycle path | route. With the configuration including the condenser, when the reformed gas flowing through the recycling path is lowered in temperature, moisture can be recovered by the condenser. Thus, the possibility of blockage of the recycling path due to condensed water is reduced.

  Further, the raw material supply device may be disposed on the raw material supply route downstream of the connection point between the recycling route and the raw material supply route and upstream of the hydrodesulfurizer 3. The raw material supplier is a device that adjusts the flow rate of the raw material supplied to the reformer 4, and is constituted by, for example, a booster and a flow rate adjustment valve, but may be constituted by any one of these. An example of the booster is a constant displacement pump. Examples of the flow rate adjustment valve include an electromagnetic valve. The raw material is supplied from the raw material supply source to the raw material supplier. The raw material supply source has a predetermined supply pressure. Examples of the raw material supply source include a raw material cylinder and a raw material infrastructure.

Here, as a hydrodesulfurization agent, when using a NiMo catalyst or a catalyst in which a CoMo catalyst and zinc oxide are combined, the hydrodesulfurizer 3 is a sulfur compound in the raw material in a temperature range of about 350 to 400 ° C. Hydrocracked. Then, the hydrodesulfurization unit 3 is removed by adsorbing the ZnO of _{H 2} S in the temperature range of about 350-400 ° C.. For example, when the raw material is city gas, dimethyl sulfide (C ₂ H ₆ S, DMS), which is a sulfur compound, is included as an odorant. The DMS is removed by the desulfurization agent in the hydrodesulfurizer 3 in the form of ZnS according to the following reaction formulas (Equations (1) and (2)) or in the form of physical adsorption.

C ₂ H ₆ S + 2H ₂ → 2CH ₄ + H ₂ S (1)
H ₂ S + ZnO → H ₂ O + ZnS (2)

In addition, the said odorant is an illustration and is not limited to this example. Examples of the odorant include other sulfur compounds such as TBM (C ₄ H ₁₀ S) or THT (C ₄ H ₈ S).

When a CuZn-based catalyst is used as the hydrodesulfurization agent, about 150 to 350 ° C. is an appropriate operating temperature for the hydrogenation reaction by the hydrodesulfurizer 3. This CuZn-based catalyst has physical adsorption performance in addition to hydrodesulfurization. The hydrodesulfurizer 3 can mainly perform physical adsorption at low temperatures and chemical adsorption (H ₂ S + ZnO → H ₂ O + ZnS) at high temperatures. In this case, the sulfur content in the raw material passed through the hydrodesulfurizer 3 is 1 vol ppb (parts per billion) or less, and usually 0.1 vol ppb or less.

  Further, the hydrodesulfurizer 3 may be provided with a temperature detector (not shown). The temperature detector may have any configuration as long as the temperature of the hydrodesulfurization agent can be detected directly or indirectly. For example, a temperature detector may be provided inside the hydrodesulfurizer 3 to directly detect the temperature of the hydrodesulfurizing agent, or a predetermined location (for example, a hydrogenated desulfurizing agent) correlated with the temperature of the hydrodesulfurizing agent. A temperature detector may be provided in a pipe connected to the desulfurizer 3) to indirectly detect the temperature of the hydrodesulfurizing agent. Examples of the temperature detector include a thermocouple or a thermistor. A controller (not shown) may perform feedback control based on the temperature detected by the temperature detector. For example, the hydrodesulfurizer 3 may be overheated when the combustion section is abnormal or when the fuel cell system 100 is under a low load (low power generation amount). Therefore, by monitoring the temperature detector, it is possible to perform feedback control by adjusting the flow rate of air for power generation so that the temperature detected by the temperature detector becomes a predetermined reference temperature within a predetermined time. Thereby, the excessive temperature rise of the hydrodesulfurizer 3 can be suppressed appropriately.

  The controller may have any configuration as long as it has a control function. The controller includes, for example, an arithmetic processing unit (not shown) and a storage unit (not shown) that stores a control program. Examples of the arithmetic processing unit include an MPU and a CPU. Examples of the storage unit include a memory. The controller may be composed of a single controller that performs centralized control, or may be composed of a plurality of controllers that perform distributed control.

  The first heat exchanger 5 includes an air path 10 through which air flows and a first exhaust gas path 20 through which exhaust gas used for heating the fuel cell 6 flows, and heat exchange between the air and the exhaust gas. The first heat exchanger 5 may have any configuration as long as air and exhaust gas can exchange heat. For example, the first heat exchanger 5 may be a counterflow heat exchanger in which the flow of air and exhaust gas are opposed, a parallel flow heat exchanger in which the flows of both fluids are parallel, It may be a cross flow heat exchanger in which the flow is orthogonal. The first heat exchanger 5 may be a plate heat exchanger or a multi-tube heat exchanger.

  The second heat exchanger 13 includes the air path 10 and a second exhaust gas path 21 through which the exhaust gas flows, and heat exchange between the air and the exhaust gas. The second heat exchanger 13 may have any configuration as long as air and exhaust gas can exchange heat. For example, the second heat exchanger 13 may be a counter flow heat exchanger in which the flow of air and exhaust gas are opposed, a parallel flow heat exchanger in which the flows of both fluids are parallel, It may be a cross flow heat exchanger in which the flow is orthogonal. The second heat exchanger 13 may be a plate heat exchanger or a multi-tube heat exchanger.

  In addition, although illustration is abbreviate | omitted, the fuel cell system 100 is provided with the air supply device which supplies air to the 2nd heat exchanger 13 via the air path 10 from the outside of a fuel cell unit. The air supplier is a device that adjusts the flow rate of air (power generation air) used for power generation of the fuel cell 6. The air supply device may be composed of, for example, a booster and a flow meter. An example of the booster is a pump. Examples of the pump include an electromagnetically driven diaphragm pump. Moreover, as a flow meter, a calorific value type | mold sensor etc. can be illustrated, for example.

  The heater 8 heats the hydrodesulfurizer 3 using exhaust gas. Specifically, the hydrodesulfurizer 3 is heated using the exhaust gas from the combustion section that burns off-gas of the fuel cell 6. The heater 8 may have any configuration as long as the hydrodesulfurizer 3 can be heated using exhaust gas. Examples of the heater 8 include a heat exchanger in which heat exchange between the hydrodesulfurizer 3 (raw material gas) and the exhaust gas is performed.

  Here, as shown in FIG. 1, in the fuel cell system 100 of the present embodiment, the exhaust gas is the first exhaust gas path 20 of the first heat exchanger 5, the heater 8, and the second exhaust gas of the second heat exchanger 13. The route 21 flows in this order. Specifically, as shown in FIG. 1, after the exhaust gas from the combustion section flows through the first heat exchanger 5 through the first exhaust gas path 20, the exhaust gas from the first exhaust gas path 20 flows into the heater 8. To do. The exhaust gas from the heater 8 flows through the second heat exchanger 13 through the second exhaust gas path 21 and is then discharged out of the fuel cell unit.

  Air from the outside of the fuel cell unit flows through the air path 10 of the second heat exchanger 13, the air path 10 of the first heat exchanger 5, and the fuel cell 6 in this order.

  As described above, the fuel cell system 100 of the present embodiment can perform appropriate temperature control of the hydrodesulfurizer 3 as compared with the conventional case when the hydrodesulfurizer 3 is heated with exhaust gas. Further, the fuel cell system 100 of the present embodiment can improve the heat recovery efficiency of the exhaust gas as compared with the conventional case. For example, in the first heat exchanger 5, the air from the second heat exchanger 13 can be further heated, and the temperature of the exhaust gas flowing through the heater 8 is a temperature range suitable for the hydrogenation reaction in the hydrodesulfurizer 3. It can be reduced to. Further, in the second heat exchanger 13, the low-temperature air from the outside of the fuel cell unit can be preheated using the exhaust gas from the hydrodesulfurizer 3.

  Moreover, as shown in FIG. 1, in the fuel cell system 100 of this embodiment, the 1st heat exchanger 5 and the 2nd heat exchanger 13 are comprised integrally. Specifically, in the first heat exchanger 5 and the second heat exchanger 13, members that form the air path 10 are shared. In the first heat exchanger 5 and the second heat exchanger 13, the first exhaust gas path 20, the second exhaust gas path 21, and the air path 10 are arranged adjacent to each other. In addition, such an integrated configuration of the first heat exchanger 5 and the second heat exchanger 13 is a member that connects each of the first heat exchanger 5, the second heat exchanger 13, and the heater 8 ( For example, it is intended to reduce the number of pipes and the flow path length, and between the first exhaust gas path 20 of the first heat exchanger 5 and the second exhaust gas path 21 of the second heat exchanger 13. It does not preclude providing an appropriate heat insulation structure. A heat insulating configuration that makes it difficult to exchange heat of the exhaust gas flowing through both will be described in the second embodiment.

  By integrally configuring the first heat exchanger 5 and the second heat exchanger 13, members for connecting the first heat exchanger 5, the second heat exchanger 13 and the heater 8 (for example, piping, etc.) ) And the channel length can be reduced. For example, in this embodiment, the member which forms the air path 10 of the 1st heat exchanger 5 and the 2nd heat exchanger 13 is made common, and the air path 10 and the 2nd heat exchange of the 1st heat exchanger 5 are used. A pipe or the like for connecting the air path 10 of the vessel 13 becomes unnecessary. Further, the first exhaust gas path 20 between the first heat exchanger 5 and the heater 8 and the second exhaust gas path 21 between the second heat exchanger 13 and the heater 8 can be easily routed. The lengths of the first exhaust gas path 20 and the second exhaust gas path 21 can be shortened. Moreover, since the fuel cell system 100 can be reduced in size by integrally configuring the first heat exchanger 5 and the second heat exchanger 13, the heat transfer area of the casing of the fuel cell system 100 can be reduced.

  As described above, the fuel cell system 100 according to the present embodiment can suppress the heat radiation from the respective members as compared with the fuel cell system 100 of FIG. 9. Therefore, the power generation efficiency of the fuel cell system 100 can be improved. Furthermore, since heat dissipation of the fuel cell system 100 can be suppressed, it becomes easier to balance the heat of the fuel cell system 100.

  In addition, by reducing the number of members (for example, piping) and the flow path length that connect the first heat exchanger 5, the second heat exchanger 13, and the heater 8, respectively, and by reducing the size of the fuel cell system 100, The manufacturing cost of the fuel cell system 100 can be reduced.

[Operation]
Hereinafter, an example of the operation of the fuel cell system 100 of the present embodiment will be described with reference to FIG. The following operation may be performed by a control program of the controller.

  In the fuel cell system 100 of this embodiment, by providing the heater 8 that heats the hydrodesulfurizer 3, the hydrodesulfurizer 3 can be heated to a temperature suitable for the hydrogenation reaction with high-temperature exhaust gas. Yes. Therefore, the exhaust gas flow and heat transfer from the combustion section will be described in detail here.

  Regarding the flow rate of exhaust gas from the combustion section and its temperature, the fuel utilization rate of reformed gas and air (power generation air) in the solid oxide fuel cell 6 (consumed as a fuel in the power generation reaction of the fuel cell 6) It is possible to control by adjusting the ratio.

  For example, the fuel utilization rate of the reformed gas and air in the fuel cell 6 is set so that the temperature range of the combustion section is about 600-900 ° C.

  In the combustion section in which the temperature range is set in this way, unused reformed gas and power generation air are combusted, and exhaust gas is generated. The exhaust gas is used for heating the reformer 4 and an evaporator for evaporating the reformed water, and a part of the heat of the exhaust gas is consumed.

  Next, the exhaust gas flows into the first heat exchanger 5 through the first exhaust gas path 20 as a heating fluid of the first heat exchanger 5. At this time, in the first heat exchanger 5, air (power generation air) used for power generation of the fuel cell 6 and the exhaust gas exchange heat. As a result, the exhaust gas is further deprived of heat, and the temperature of the exhaust gas is lowered to a temperature range suitable for the hydrogenation reaction of the hydrodesulfurizer 3. Then, the exhaust gas flows into the heater 8 through the first exhaust gas path 20. That is, the temperature of the exhaust gas in the combustion section is as high as about 600 ° C. to 900 ° C., for example. However, the exhaust gas is used to heat the reformer 4 and the evaporator, and the first heat exchanger 5 performs heat exchange with the power generation air so that the temperature of the exhaust gas reaches an appropriate temperature before reaching the heater 8. Can cool down to In particular, for example, when generating 1 kW using the fuel cell 6, it is necessary to heat air of 50 L / min or more from the outside temperature to about 400-800 ° C. In the first heat exchanger 5, A large amount of heat is required. Therefore, the heat required for air heating can be covered by the heat of the exhaust gas.

  Thus, the temperature of the exhaust gas takes into consideration the flow rate and temperature of the exhaust gas in the combustion section, the amount of heat absorbed by the reformer 4 and the evaporator, the amount of heat absorbed by the first heat exchanger 5, and the like. So that the desired value is obtained.

  The hydrodesulfurizer 3 is heated by flowing an appropriate temperature exhaust gas through the heater 8. When a CuZn-based catalyst is used as the hydrodesulfurization agent of the hydrodesulfurizer 3, the flow rate and temperature of the exhaust gas in the combustion section and the reforming so that the temperature of the exhaust gas of the heater 8 is about 150-350 ° C. The amount of heat absorbed by the condenser 4 and the evaporator, the amount of heat absorbed by the first heat exchanger 5, and the like are controlled. When using a Ni-Mo-based or Co-Mo-based catalyst in combination with zinc oxide as the hydrodesulfurization agent of the hydrodesulfurizer 3, the temperature of the exhaust gas from the heater 8 is about 350-450 ° C. Thus, the flow rate and temperature of the exhaust gas in the combustion section, the amount of heat absorbed by the reformer 4 and the evaporator, the amount of heat absorbed by the first heat exchanger 5 and the like are controlled. As described above, the temperature of the hydrodesulfurizer 3 is controlled to a temperature suitable for the hydrogenation reaction.

  The exhaust gas that has passed through the heater 8 flows into the second heat exchanger 13 through the second exhaust gas path 21 as a heating fluid of the second heat exchanger 13. At this time, in the second heat exchanger 13, the air for power generation from the outside of the fuel cell unit and the exhaust gas exchange heat. Thereby, low-temperature power generation air can be preheated. For example, heat is further deprived from the exhaust gas so that the temperature of the exhaust gas is about 150 ° C. to 200 ° C., and is discharged out of the fuel cell unit. The heat of the exhaust gas discharged outside the fuel cell unit may be recovered by heat exchange with water, and the heat-recovered water may be stored in a hot water storage tank.

  As described above, the fuel cell system 100 of the present embodiment can perform appropriate temperature control of the hydrodesulfurizer 3 as compared with the conventional case when the hydrodesulfurizer 3 is heated with exhaust gas. Further, the fuel cell system 100 of the present embodiment can improve the heat recovery efficiency of the exhaust gas as compared with the conventional case.

(First embodiment)
The fuel cell system according to the first example of the first embodiment is the fuel cell system according to the first embodiment, wherein the first heat exchanger and the second heat exchanger are cross flow heat exchangers.

  With this configuration, the heat exchange performance of the first heat exchanger and the second heat exchanger is improved as compared with the case where a parallel flow heat exchanger is used.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment except for the above features.

[Device configuration]
FIG. 2 is a diagram illustrating an example of a heat exchanger of the fuel cell system according to the first example of the first embodiment. In FIG. 2, for convenience, the air path 10 of the first heat exchanger 5A and the second heat exchanger 13A, the first exhaust gas path 20 of the first heat exchanger 5A, and the second exhaust gas of the second heat exchanger 13A. The route 21 is divided and illustrated.

  As shown in FIG. 2, the exhaust gas in the first exhaust gas path 20 and the exhaust gas in the second exhaust gas path 21 are rectified in the dispersion part 30 and the dispersion part 31 and flow in the left-right direction. On the other hand, the air in the air path 10 is rectified in the dispersion portion 32 and flows in the vertical direction orthogonal to the left-right direction. That is, the first heat exchanger 5A and the second heat exchanger 13B are cross flow heat exchangers in which the flows of air and exhaust gas are orthogonal.

  As described above, the heat exchange performance of the first heat exchanger 5A and the second heat exchanger 13A is improved as compared with the case where a parallel flow heat exchanger is used.

(Second embodiment)
The fuel cell system of the second example of the first embodiment is the same as the fuel cell system of the first embodiment, but the first heat exchanger and the second heat exchanger are plate heat exchangers.

  Thereby, compared with the case where a 1st heat exchanger and a 2nd heat exchanger use a double pipe type heat exchanger etc., for example, the performance of heat exchange improves and it can comprise compactly. Therefore, these 1st heat exchangers and 2nd heat exchangers can be constituted integrally with small size and high efficiency.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment except for the above features.

[Device configuration]
FIG. 3 is a diagram illustrating an example of a heat exchanger of the fuel cell system according to the second example of the first embodiment. The upper diagram in FIG. 3 is a side view of the heat exchanger, and the lower diagram is a top view of the heat exchanger.

  As shown in FIG. 3, exhaust gas and air flow into and out of the rectangular housing 40. In addition, the first heat exchanger 5B and the second heat exchanger 13B are accommodated integrally in the housing 40. Specifically, the first heat exchanger 5B and the second heat exchanger 13B include an exhaust gas heat transfer plate (not shown) pressed into a waveform and an air heat transfer plate (not shown). They are assembled by alternately overlapping with gaskets. That is, the first heat exchanger 5B and the second heat exchanger 13B are plate heat exchangers.

  By the above, the 1st heat exchanger 5B and the 2nd heat exchanger 13B can improve the performance of heat exchange compared with the case where a double pipe type heat exchanger etc. are used, for example, and can constitute it compactly. Therefore, the first heat exchanger 5B and the second heat exchanger 13B can be integrally configured with a small size and high efficiency.

(Second Embodiment)
The fuel cell system according to the second embodiment is the fuel cell system according to any one of the first embodiment, the first example of the first embodiment, and the second example of the first embodiment. The space between the 1 exhaust gas path and the second exhaust gas path of the second heat exchanger is insulated. For example, a space is formed between the first exhaust gas path and the second exhaust gas path.

  By configuring the first exhaust gas path of the first heat exchanger and the second exhaust gas path of the second heat exchanger as heat insulation, heat transfer between the two exhaust gas paths can be reduced. Therefore, the heat exchange performance is improved as compared with the case where such a heat insulating configuration is not adopted.

  The fuel cell system of this embodiment is configured in the same manner as the fuel cell system of any one of the first embodiment, the first example of the first embodiment, and the second example of the first embodiment, except for the above-described features. May be.

[Device configuration]
FIG. 4 is a diagram illustrating an example of a fuel cell system according to the second embodiment.

  As shown in FIG. 4, the fuel cell system 100 includes a fuel cell 6, a reformer 4, a hydrodesulfurizer 3, a heater 8, an air path 10, a first exhaust gas path 20, The heat exchanger 5, the second exhaust gas path 21, the second heat exchanger 13, and the heat insulating air layer 29 are provided. Regarding the fuel cell 6, the reformer 4, the hydrodesulfurizer 3, the heater 8, the air path 10, the first exhaust gas path 20, the first heat exchanger 5, the second exhaust gas path 21, and the second heat exchanger 13 Since it is the same as that of 1st Embodiment, description is abbreviate | omitted.

  In the fuel cell system 100 of the present embodiment, the first exhaust gas path 20 of the first heat exchanger 5 and the second exhaust gas path 21 of the second heat exchanger 13 are insulated. The fuel cell system 100 may have any configuration as long as it can insulate between the first exhaust gas path 20 and the second exhaust gas path 21. In the present embodiment, as shown in FIG. 4, a space is formed between the first exhaust gas path 20 and the second exhaust gas path 21. Thereby, between the both exhaust gas paths 20 and 21 is comprised as the heat insulation air layer 29. FIG. Moreover, you may provide appropriate heat insulating materials, such as a ceramic, in this space.

  The temperature of the exhaust gas flowing through the first exhaust gas path 20 of the first heat exchanger 5 is higher than the temperature of the exhaust gas flowing through the second exhaust gas path 21 of the second heat exchanger 13.

  Therefore, as described above, the first exhaust gas path 20 of the first heat exchanger 5 and the second exhaust gas path 21 of the second heat exchanger 13 are configured to be insulated so that heat transfer between the exhaust gas paths 20 and 21 is achieved. Can be reduced. Therefore, the heat exchange performance is improved as compared with the case where such a heat insulating configuration is not adopted.

  In addition, in FIG. 4, the example which heat-insulates between the 1st exhaust gas path | route 20 of the 1st heat exchanger 5 of 1st Embodiment (FIG. 1) and the 2nd exhaust gas path | route 21 of the 2nd heat exchanger 13 is shown. However, it is not limited to this.

  The first exhaust gas path 20 of the first heat exchanger 5A of the first example (FIG. 2) of the first embodiment and the second exhaust gas path 21 of the second heat exchanger 13A may be insulated. You may insulate between the 1st exhaust gas path 20 of the 1st heat exchanger 5B of the 2nd example (Drawing 3) of the 1st embodiment, and the 2nd exhaust gas path 21 of the 2nd heat exchanger 13B. When these heat exchangers insulate both exhaust gas paths, as described above, the heat exchange performance is improved as compared with the case where such a heat insulation structure is not adopted.

(Third embodiment)
The fuel cell system according to the third embodiment is the same as the fuel cell system according to the first embodiment or the second embodiment. The cylindrical body that forms the air path includes the cylindrical body that forms the first exhaust gas path, and the second exhaust gas path. Concentric with the cylindrical body to be formed.

  By configuring the first heat exchanger and the second heat exchanger in a cylindrical shape, the heat transfer regions of the first heat exchanger and the second heat exchanger can be secured over the entire circumference. Therefore, the first heat exchanger and the second heat exchanger can be configured with high efficiency. Further, the surface area of the fuel cell system can be reduced, and the fuel cell system can be made compact. Therefore, further miniaturization and high efficiency of the fuel cell system can be realized.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment or the second embodiment except for the above features.

[Device configuration]
5A and 5B are diagrams illustrating an example of a heat exchanger of the fuel cell system according to the third embodiment. 5A and 5B are CC cross-sectional views of the upper plan view.

  In the example shown in FIG. 5A, the cylindrical body 10A that forms the air path of the first heat exchanger 105A and the second heat exchanger 113A has the first exhaust gas path of the first heat exchanger 105A centered on the central axis 200. The cylindrical body 20A to be formed and the cylindrical body 21A to form the second exhaust gas path of the second heat exchanger 113A are configured concentrically.

  In FIG. 5A, a cylindrical body 20A and a cylindrical body 21A are provided on the outside so as to cover the cylindrical body 10A. The outer surfaces of the cylindrical body 20A and the cylindrical body 21A are covered with a heat insulating material (not shown). Air from the end of the cylindrical body 10A is sent to a fuel cell (not shown) in the cylindrical body 20A and the cylindrical body 21A via a pipe (not shown).

  In the example shown in FIG. 5B, the cylindrical body 10B that forms the air path of the first heat exchanger 105B and the second heat exchanger 113B has the first exhaust gas of the first heat exchanger 105B centered on the central axis 200. The cylindrical body 20B that forms the path and the cylindrical body 21B that forms the second exhaust gas path of the second heat exchanger 113B are configured concentrically.

  Moreover, in FIG. 5B, the cylindrical body 10B is provided outside so as to cover the cylindrical body 20B and the cylindrical body 21B. And the outer surface of this cylindrical body 10B is covered with the heat insulating material which is not shown in figure. The air from the end of the cylindrical body 10B is sent to a fuel cell (not shown) in the cylindrical body 10B via a pipe (not shown).

  As described above, the first heat exchangers 105A and 105B and the second heat exchangers 113A and 113B are configured in a cylindrical shape, so that the heat transfer regions of the first heat exchangers 105A and 105B and the second heat exchangers 113A and 113B are formed. Can be secured over the entire circumference. Therefore, the first heat exchangers 105A and 105B and the second heat exchangers 113A and 113B can be configured with high efficiency. Further, the surface area of the fuel cell system can be reduced, and the fuel cell system can be made compact. Therefore, further miniaturization and high efficiency of the fuel cell system can be realized.

  Moreover, the temperature of the exhaust gas flowing through the cylindrical body 20B and the cylindrical body 21B is higher than the temperature of the air flowing through the cylindrical body 10B. Therefore, the first heat exchanger 105B and the second heat exchanger 113B in FIG. 5B radiate the exhaust gas to the outside of the fuel cell system as compared to the first heat exchanger 105A and the second heat exchanger 113A in FIG. 5A. Can be suppressed.

  On the other hand, as described in the second embodiment, it is preferable to insulate the cylindrical body 20A and the cylindrical body 21A through an insulating air layer 29 or the like as shown in FIG. 5A. In the example shown in FIG. 5A, since the cylindrical body 20A and the cylindrical body 21A are provided outside the cylindrical body 10A, the cylindrical body 20A and the cylindrical body 21A can be easily heat-insulated. That is, the first heat exchanger 105A and the second heat exchanger 113A in FIG. 5A are easier to manufacture than the first heat exchanger 105B and the second heat exchanger 113B in FIG. 5B.

  According to one embodiment of the present invention, when a hydrodesulfurizer is heated with exhaust gas, appropriate temperature control of the hydrodesulfurizer can be performed as compared with the conventional case. Thus, one embodiment of the present invention can be used, for example, in a fuel cell system.

3 Hydrodesulfurizer 4 Reformer 5 First heat exchanger 6 Fuel cell 8 Heater 10 Air path 13 Second heat exchanger 20 First exhaust gas path 21 Second exhaust gas path 29 Insulated air layer 100 Fuel cell system

Claims (7)

A fuel cell that generates electricity using fuel and air obtained by reforming the raw materials; and
A hydrodesulfurizer for removing sulfur components in the raw material;
A first heat exchanger that includes an air path through which the air flows and a first exhaust gas path through which the exhaust gas used to heat the fuel cell flows, and heat exchange between the air and the exhaust gas;
A second heat exchanger comprising the air path and a second exhaust gas path through which the exhaust gas flows, wherein the air and the exhaust gas exchange heat;
A heater for heating the hydrodesulfurizer using the exhaust gas;
With
The exhaust gas flows in this order through the first exhaust gas path of the first heat exchanger, the heater and the second exhaust gas path of the second heat exchanger,
The air flows through the air path of the second heat exchanger, the air path of the first heat exchanger, and the fuel cell in this order,
A fuel cell system in which the first heat exchanger and the second heat exchanger are integrally formed.   The fuel cell system according to claim 1, wherein the fuel cell is a solid oxide fuel cell.   The fuel cell system according to claim 1 or 2, wherein the first heat exchanger and the second heat exchanger are cross-flow heat exchangers.   The fuel cell system according to claim 1 or 2, wherein the first heat exchanger and the second heat exchanger are plate heat exchangers.   The fuel cell system according to any one of claims 1 to 4, wherein a space between the first exhaust gas path and the second exhaust gas path is insulated.   The fuel cell system according to claim 5, wherein a space is formed between the first exhaust gas path and the second exhaust gas path. The cylindrical body forming the air path is configured concentrically with the cylindrical body forming the first exhaust gas path and the cylindrical body forming the second exhaust gas path. The fuel cell system according to any one of the above.

Images