JP2014086337A - Solid oxide fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell system capable of efficiently and stably operating while reducing the amount of water to be supplied.SOLUTION: The solid oxide fuel cell system according to the present invention includes: a solid oxide fuel cell 6 that generates power by utilizing power generation reaction using air and a fuel gas supplied; a combustion section 23 that allows a fuel not used in the solid oxide fuel cell 6 to combust with air and generates an exhaust gas; an air heat exchanger 5 that heats air to be supplied to the solid oxide fuel cell 6 by utilizing the heat of the exhaust gas; a desulfurizing section 3 that removes a sulfur component contained in the supplied material gas by means of hydrogen desulfurization; a first reformer 4 that generates the fuel gas from the material gas from which the sulfur component is removed by the desulfurizing section 3; a second reformer 8 that reforms by means of partial oxidation a part of the material gas from which the sulfur component is removed by the desulfurizing section 3 and returns the obtained reformed gas to the upstream of the desulfurizing section 3.

Description

  The present invention relates to a solid oxide fuel cell system including a desulfurization section that removes a sulfur component from a raw material gas (raw material) containing hydrocarbons.

  In a solid oxide fuel cell system using hydrocarbons as a source gas (raw fuel gas), for example, steam reforming using steam is used to reform the source gas. A steam reforming catalyst is used to promote the steam reforming. However, the raw material gas contains an odorant or a sulfur compound, which may cause the steam reforming catalyst to be deteriorated. is there. Therefore, in order to prevent deterioration of the steam reforming catalyst, a desulfurization apparatus that reduces the odorant or sulfur compound contained in the raw material gas is used.

  As such a desulfurization apparatus, for example, a sulfur compound is reacted with hydrogen on a catalyst (Ni-Mo system, Co-Mo system) to convert it into hydrogen sulfide, and the hydrogen sulfide is taken into zinc oxide and removed. Examples thereof include a hydrodesulfurization apparatus that performs desulfurization by a so-called hydrodesulfurization method.

  The hydrodesulfurization apparatus requires hydrogen when performing desulfurization by the hydrodesulfurization method, but the source gas usually does not contain hydrogen. Therefore, a solid oxide fuel cell system having a configuration for supplying hydrogen to a hydrodesulfurization apparatus has been proposed (for example, Patent Documents 1 and 2).

  More specifically, in Patent Document 1, as shown in FIG. 7, a part of the fuel gas flowing through the reformer 110 is returned to the upstream side of the pressure boosting unit 111 through the recycle gas supply path 113. A structured solid oxide fuel cell system is disclosed. The returned fuel gas is boosted by the boosting means 111 and supplied to the desulfurizer 102.

  Moreover, in patent document 2, as shown in FIG. 8, the solid oxide fuel cell system which has the structure shown below is proposed. That is, in the solid oxide fuel ionization system of Patent Document 2, the water mixed in the mixer 220 and the raw fuel gas after desulfurization are supplied to the evaporator 226. And the structure by which a part of raw fuel gas after desulfurization containing water vapor | steam supplied from the evaporator 226 to the reformer 206 is returned to the fuel gas supply path 216 via the branch return flow path 242 is disclosed. . In addition, a hydrocarbon reforming catalyst is provided in the double pipe 244 of the branch return flow path 242, and thereby the hydrogen-containing gas obtained by reforming the hydrocarbon is returned to the upstream side of the booster 217. be able to. The returned hydrogen-containing gas is boosted by the booster 217 and supplied to the desulfurizer 204.

JP 2011-216308 A Japanese Patent No. 4911927 Japanese Patent No. 2999307

  However, the conventional solid oxide fuel cell system has a problem that the amount of water to be supplied can be reduced and it cannot be operated efficiently and stably.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a solid oxide fuel cell system capable of reducing the amount of water to be supplied and operating efficiently and stably. It is to provide.

  In order to solve the above-described problems, a solid oxide fuel cell system according to the present invention includes a solid oxide fuel cell that generates power by a power generation reaction using supplied fuel and air, and the solid oxide. Combustion unit that generates exhaust gas by burning unused fuel and air in a fuel cell, and air heat exchange that heats the air supplied to the solid oxide fuel cell using heat of the exhaust gas , A desulfurization section that removes sulfur components contained in the supplied raw material by hydrodesulfurization, and a first reformer that generates reformed gas that serves as the fuel from the raw material from which sulfur components have been removed by the desulfurization section And a second reformer for reforming a part of the raw material from which the sulfur component has been removed by the desulfurization unit by a partial oxidation method and returning the obtained reformed gas to the upstream side of the desulfurization unit.

  The solid oxide fuel cell system according to the present invention is configured as described above, and has the effect of reducing the amount of water to be supplied and allowing it to operate efficiently and stably.

It is the schematic diagram which showed an example of the structure of the solid oxide fuel cell system which concerns on embodiment. It is the schematic diagram which showed an example of the structure of the solid oxide fuel cell system which concerns on embodiment. It is the schematic diagram which showed an example of the structure of the solid oxide fuel cell system which concerns on the modification 1 of this embodiment. It is the schematic diagram which showed an example of the structure of the solid oxide fuel cell system which concerns on the modification 1 of this embodiment. It is a figure which shows typically an example of a structure of the 2nd reformer with which the solid oxide fuel cell system which concerns on the modification 1 shown in FIG.3 and FIG.4 is provided. It is the schematic diagram which showed an example of the structure of the solid oxide fuel cell system which concerns on the modification 2 of this embodiment. It is a schematic diagram which shows a prior art and showed an example of the structure of the solid oxide fuel cell system. It is a schematic diagram which shows a prior art and showed an example of the structure of the solid oxide fuel cell system.

(Background to obtaining one embodiment of the present invention)
As a result of intensive research on the conventional solid oxide fuel cell system described in “Background Art”, the present inventor has increased the amount of water to be supplied and efficiently It has been found that there may be a problem that it cannot be operated stably. And as a result of repeated investigations on this problem, the present inventor has obtained the following knowledge.

  That is, in the solid oxide fuel cell system according to Patent Document 1, the reformer 110 performs hydrodesulfurization in the desulfurizer 112 in addition to the fuel gas (hydrogen-containing gas) used in the solid oxide fuel cell 114. It is necessary to generate hydrogen to carry out. Therefore, in addition to the reforming water necessary for generating the fuel gas, it is necessary to further supply reforming water for generating hydrogen necessary for hydrodesulfurization to the reformer 110. There is a problem that the amount of reforming water to be increased.

  Further, as described above, in the solid oxide fuel cell system according to Patent Document 2, a part of the raw fuel gas after desulfurization including water vapor supplied from the evaporator 226 to the reformer 206 is branched and returned. It was the structure which distribute | circulates the path 242. For this reason, dew condensation may occur in the branch return flow path 242. When dew condensation occurs in the branch return flow path 242, pressure loss occurs due to water clogging due to this dew condensation, and the raw fuel gas after desulfurization including water vapor hardly flows in the branch return flow path 242. . As a result, the flow rate of the hydrogen-containing gas returned to the upstream side of the booster 217 decreases, and there arises a problem that the desulfurizer 204 cannot be desulfurized to a desired sulfur concentration.

  Furthermore, in the solid oxide fuel cell system of Patent Document 2, the hydrogen-containing gas that has flowed through the branch return flow path 242 flows through the booster 217 and the desulfurizer 204. For this reason, when the operation of the solid oxide fuel cell system is stopped and the temperature in the system decreases, condensation may occur in the desulfurizer 204 or the booster 217. Therefore, the solid oxide coulometric battery system according to Patent Document 2 has a problem that it cannot realize a highly efficient and stable operation.

  Based on these findings, the present inventors can devise a reformer to reduce the amount of water to be supplied and to operate the solid oxide fuel cell system efficiently and stably. As a result, the present invention has been found. And in this invention, the aspect shown below is provided.

  A solid oxide fuel cell system according to a first aspect of the present invention includes a solid oxide fuel cell that generates electric power by a power generation reaction using supplied fuel and air, and the solid oxide fuel cell. A combustion section that generates exhaust gas by burning unused fuel and air, an air heat exchanger that heats the air supplied to the solid oxide fuel cell using heat of the exhaust gas, and a supply A desulfurization unit that removes sulfur components contained in the raw material by hydrodesulfurization, a first reformer that generates a reformed gas that serves as the fuel from the raw material from which sulfur components have been removed by the desulfurization unit, and the desulfurization A second reformer that reforms a part of the raw material from which the sulfur component has been removed by the part by a partial oxidation method and returns the obtained reformed gas to the upstream side of the desulfurization part.

  According to the above configuration, since the combustion unit and the air heat exchanger are provided, the air supplied to the solid oxide fuel cell can be heated by the heat of the exhaust gas generated in the combustion unit. For this reason, air of an appropriate temperature can be supplied to the solid oxide fuel cell.

  Further, since the first reformer, the second reformer, and the desulfurization unit are provided, the first reformer can efficiently generate the fuel used for the power generation reaction from the raw material desulfurized in the desulfurization unit. . On the other hand, in the second reformer, in order to supply hydrogen used when the desulfurization part hydrodesulfurizes the raw material, the reformed gas generated by reforming the desulfurized raw material by a partial oxidation method is used. It returns to the upstream side of this desulfurization part. For this reason, the desulfurization part can remove a sulfur component from a raw material efficiently by hydrodesulfurization.

  Further, since the second reformer reforms the raw material by the partial oxidation method, there is no need to add water (reformed water) to the reformer in order to generate hydrogen used for hydrodesulfurization. In addition, there is no concern that water is mixed with the raw material supplied to the desulfurization section. For this reason, it is possible to prevent water clogging from occurring in the path for returning the reformed gas from the second reformer to the upstream side of the desulfurization unit, and pressure loss occurs due to water clogging. It is possible to prevent the problem that the flow becomes worse and the desulfurization part cannot be desulfurized to a desired sulfur concentration.

  Therefore, the solid oxide fuel cell system has an effect that the amount of water to be supplied can be reduced and can be efficiently and stably operated.

  In the solid oxide fuel cell system according to the second aspect of the present invention, in the first aspect described above, the desulfurization unit is detachably provided in the solid oxide fuel cell system. May be.

  According to the above configuration, since the desulfurization part is detachably provided in the solid oxide fuel cell system, the desulfurization part can be easily replaced when the desulfurization catalyst filled in the desulfurization part deteriorates. Therefore, further long-term operation of the solid oxide fuel cell system can be facilitated.

  Moreover, the solid oxide fuel cell system according to the third aspect of the present invention is the water supplied to the reformer for use in the steam reforming reaction in the first or second aspect described above. You may be comprised so that it may have an evaporator for vaporizing.

  According to the above configuration, the evaporator is provided, and the steam reforming reaction of the fuel gas can be performed by the reformer. Therefore, it is possible to realize a solid oxide fuel cell system having excellent fuel efficiency.

  The solid oxide fuel cell system according to a fourth aspect of the present invention is the solid oxide fuel cell system according to any one of the first to third aspects described above, wherein the air heat exchanger adds the heat of the exhaust gas. The air supplied to the solid oxide fuel cell may be heated by the heat of the reformed gas generated by the second reformer.

  According to the above configuration, the reformed gas generated by the second reformer can be lowered in temperature, and heat deterioration of piping and the like constituting the path until the reformed gas is returned to the upstream side of the desulfurization unit. Can be suppressed. In addition, the air heat exchanger can heat the air supplied to the solid oxide fuel cell using the heat of the reformed gas generated by the second reformer in addition to the heat of the exhaust gas, The capacity of the air heat exchanger itself can be reduced.

  In the solid oxide fuel cell system according to the fifth aspect of the present invention, the second reformer is disposed adjacent to the air heat exchanger in the fourth aspect described above. The heat exchanger may be provided with a heat exchanging section for exchanging heat between the air heat exchanger and the reformed gas.

  According to the above configuration, since the second reformer includes the heat exchange unit, the heat of the reformed gas is efficiently transmitted to the air heat exchanger. As a result, the solid oxide fuel cell is transferred to the air heat exchanger. The supplied air can be heated.

  Further, the solid oxide fuel cell system according to the sixth aspect of the present invention is the pressure increasing unit that pressurizes the raw material and supplies it to the desulfurization unit in any one of the first to fifth aspects described above. A recycle path that is a path for guiding the reformed gas generated by the second reformer to the upstream side of the booster section, and a fuel that is provided in the recycle path and flows through the recycle path And a condenser for condensing the contained water.

  According to the above configuration, since the recycling path is provided, the reformed gas generated by the second reformer can be guided to the upstream side of the booster. In addition, since a condenser is provided in the recycling path, when the reformed gas flowing through the recycling path is cooled, moisture can be recovered by the condenser, so that water in the path due to condensed water can be recovered. That is, problems such as corrosion or breakage of the booster can be suppressed.

  Hereinafter, embodiments of the present invention 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.

  A solid oxide fuel cell system according to an embodiment will be described with reference to FIGS. 1 and 2. 1 and 2 are schematic views showing an example of a configuration of a solid oxide fuel cell system according to an embodiment. In FIG. 1, the structure when the solid oxide fuel cell system which concerns on embodiment is seen from the side part is shown typically. In FIG. 2, the structure when the inside of the housing | casing 7 of the solid oxide fuel cell system which concerns on embodiment is seen from the top is shown typically.

  As shown in FIGS. 1 and 2, the solid oxide fuel cell system includes a desulfurization unit 3, a first reformer 4, an air heat exchanger 5, a solid oxide fuel cell 6, and a second reformer 8. The evaporator 9 and the decompression unit 18 are arranged inside the housing 7. In addition, a combustion unit 23 is provided on the solid oxide fuel cell 6.

  In the solid oxide fuel cell system, the raw material gas (raw fuel gas) supplied from the outside of the casing 7 is reformed by the first reformer 4, and the reformed reformed gas (fuel gas) and the outside are reformed. The solid oxide fuel cell 6 is configured to generate power by a power generation reaction using the air supplied from.

  In the embodiment, a gas supplied from the outside through the raw material gas path 1 is referred to as a raw material gas (raw material), a sulfur component is removed from the raw material gas, and the first reformer 4 is reformed by a reforming reaction. The reformed gas is referred to as fuel gas (fuel). Further, the reformed gas reformed by the reforming reaction in the second reformer 8 is referred to as the reformed gas as it is, and is distinguished from the reformed gas (fuel gas) used in the solid oxide fuel cell 6. It shall be.

  In the solid oxide fuel cell system, when the solid oxide fuel cell 6 operates (power generation), the combustion unit 23 burns fuel gas and air that have not been used for the power generation reaction, High-efficiency operation is realized by generating exhaust gas and using its thermal energy effectively. Further, in the solid oxide fuel cell system, a heat insulating portion 22 made of a heat insulating material is provided inside the housing 7 and is configured to block heat radiation from the inside of the housing 7 to the outside as much as possible. ing.

  In the solid oxide fuel cell system, the booster 2 is arranged outside the housing 7. The pressurizing unit 2 is configured to pressurize the source gas supplied through the source gas path 1 and introduce it into the desulfurization unit 3 disposed in the casing 7. In addition, as the source gas supplied through the source gas path 1, city gas or gas mainly composed of hydrocarbons such as propane gas can be used.

The desulfurization unit 3 is for removing sulfur components contained in the raw material gas by a hydrodesulfurization method. In the present embodiment, the desulfurization unit 3 is detachably disposed on the right side surface of the casing 7 in FIG. Moreover, as a desulfurization agent with which this desulfurization part 3 is filled, the desulfurization agent containing copper and zinc is mentioned, for example (for example, patent document 3). The desulfurizing agent is not limited to this desulfurizing agent as long as it can perform hydrodesulfurization, and may be a combination of a Ni—Mo based or Co—Mo based catalyst and zinc oxide. In the case of a desulfurization agent in which a Ni—Mo or Co—Mo catalyst and zinc oxide are combined, the desulfurization unit 3 hydrocrackes organic sulfur in the raw material gas in a temperature range of 350 to 400 ° C. The desulfurization unit 3, the generated _{H 2} S, is removed by adsorption to ZnO at a temperature range of 350 to 400 ° C..

For example, when the source gas is city gas, dimethyl sulfide (C ₂ H ₆ S, DMS), which is a sulfur compound, is contained as an odorant. The DMS is removed by the desulfurization agent 3 in the desulfurization section 3 in the form of ZnS according to the following reaction formulas (formulas (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)
The odorant is not limited to the above-described DMS, and may be another sulfur compound such as TBM (C ₄ H ₁₀ S) or THT (C ₄ H ₈ S).

In the case of using a desulfurizing agent containing copper and zinc, the desulfurization part 3 performs desulfurization in a temperature range of about 10 to 400 ° C, preferably about 150 to 300 ° C. This copper zinc-based desulfurization agent has a physical adsorption capability in addition to a hydrodesulfurization capability, and 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 contained in the raw material gas after desulfurization is 1 vol ppb (parts per billion) or less, usually 0.1 vol ppb or less.

  Thus, when the desulfurization part 3 is filled with a Ni-Mo-based or Co-Mo-based catalyst, or a desulfurizing agent containing either copper and zinc, the sulfur component removal amount per unit volume is increased. Therefore, when the above-described desulfurizing agent is used, the amount of the desulfurizing agent necessary for removing sulfur to a desired sulfur concentration can be reduced.

  The raw material gas desulfurized by the desulfurization unit 3 as described above is divided into the first post-desulfurization raw material gas path 14 and the second post-desulfurization raw material gas path 15, and the first reformer 4 (evaporator 9) Each is supplied to the second reformer 8.

  Next, the first reformer 4 will be described. The first reformer 4 may be used only for partial oxidation reforming, but not only partial oxidation reforming reaction but also steam reforming reaction to realize more efficient operation. It is advantageous to have specifications that can be used. Therefore, as shown in FIG. 1, in the present embodiment, an evaporator 9 is disposed on the upstream side of the first reformer 4, and water supplied through the reformed water path 11 is mixed with the desulfurized raw material gas. The first reformer 4 can be supplied.

In addition, as the reforming catalyst filled in the first reformer 4, the Al ₂ O ₃ (alumina) sphere surface is impregnated with Ni and supported, or the Al ₂ O ₃ sphere surface is provided with ruthenium. What was done can be used suitably.

By the way, when the solid oxide fuel cell system is started, the first reformer 4 has insufficient heat energy to perform the steam reforming reaction that is an endothermic reaction. Therefore, when the solid oxide fuel cell system is started, the first reformer is not supplied to the first reformer 4 (evaporator 9) from the reformed water path 11 but through the reformed air path 12. The first reformer 4 performs the partial oxidation reforming reaction (reaction by the partial oxidation method) represented by the following formula (3) using the air introduced into 4 to generate hydrogen gas and carbon monoxide. To do.
_{C n H m + (n /} 2) O 2 → n · CO + (m / 2) H 2 (n, m is an arbitrary natural number) (3)
Then, these hydrogen gas and carbon monoxide are supplied to the solid oxide fuel cell 6 through the fuel gas supply path 16 and are combined with the air supplied through the air supply path 17 to perform a power generation reaction.

As the solid oxide fuel cell system starts up and power generation proceeds, the temperature of the first reformer 4 rises. That is, the partial oxidation reforming reaction represented by the above formula (3) is an exothermic reaction, and the temperature of the first reformer 4 is increased by the exhaust gas and the radiant heat from the combustion unit 23. And if the temperature of the 1st reformer 4 will be 400 degreeC or more, for example, it will become possible to perform the steam reforming reaction shown by the following formula | equation (4) in parallel.
_{C n H m + n · H} 2 O → n · CO + (m / 2 + n) H 2 (n, m is an arbitrary natural number) (4)
Compared with the partial oxidation reforming reaction represented by the formula (3), the steam reforming reaction represented by the formula (4) described above has a larger amount of hydrogen that can be generated from the same amount of hydrocarbon (C _n H _m ). As a result, the amount of reformed gas (fuel gas) available for power generation reaction in the solid oxide fuel cell 6 increases. That is, the steam reforming reaction can generate fuel gas more efficiently. Further, since the steam reforming reaction shown in the formula (4) is an endothermic reaction, the heat generated by the partial oxidation reforming reaction shown in the formula (3), the heat held by the exhaust gas discharged from the combustion unit 23, and the combustion unit 23 The steam reforming reaction is allowed to proceed while supplementing the necessary amount of heat using the radiant heat from. And if the temperature of the 1st reformer 4 will be 600 degreeC or more, for example, the amount of heat required for the steam reforming reaction of Formula (4) can be supplemented only by the heat of the exhaust gas and the radiant heat from the combustion section 23. Therefore, it is possible to switch to the operation of only the steam reforming reaction.

  The first reformer 4 included in the solid oxide fuel cell system according to the present embodiment is configured to switch the operation from the partial oxidation reforming reaction to the steam reforming reaction as described above. Only the oxidation reforming reaction may be performed.

  The evaporator 9 evaporates the reformed water in order to perform the steam reforming reaction in the first reformer 4. More specifically, the evaporator 9 uses the heat of the exhaust gas discharged from the combustion unit 23 and the radiant heat from the combustion unit 23 to vaporize the water supplied from the reforming water path 11, thereby desulfurizing unit 3. And mixed with the raw material gas after desulfurization supplied from. Then, the evaporator 9 introduces the mixed raw material gas into the first reformer 4.

  The air heat exchanger 5 is for heating air (power generation air) used for a power generation reaction in the solid oxide fuel cell 6 and is provided above the combustion unit 23 and at a position facing it. . The air heat exchanger 5 heats air (power generation air) supplied from the outside through the air supply path 10 by heat exchange with exhaust gas and radiant heat from the combustion unit 23. For example, the air after flowing through the air heat exchanger 5 is heated to 400 to 800 ° C. The heated air is supplied to the solid oxide fuel cell 6. The exhaust gas from which a part of the heat held by the heat exchange with the air is removed by the air heat exchanger 5 is guided to the outside of the housing 7 through the exhaust gas path 20.

  As described above, the solid oxide fuel cell 6 generates power by a power generation reaction using the fuel gas supplied through the fuel gas supply path 16 and the air (air for power generation) supplied through the air supply path 17. Is. That is, the solid oxide fuel cell 6 has a fuel electrode to which fuel gas is supplied and an air electrode to which power generation air is supplied, and generates power by performing a power generation reaction between the fuel electrode and the air electrode. A plurality of fuel cell single cells are connected in series to form a cell stack. Note that the solid oxide fuel cell 6 may further have a configuration in which cell stacks connected in series are connected in parallel.

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

  Further, the solid oxide fuel cell system according to the present embodiment includes a second reformer 8 in addition to the first reformer 4 described above. The second reformer 8 generates reformed gas (hydrogen-containing gas) in order to supply hydrogen to be used for hydrodesulfurization performed in the desulfurization section 3 to the desulfurization section 3. The generated reformed gas is returned to the raw material gas path 1 through the recycle path 19. For this reason, it becomes possible to add hydrogen to the raw material gas supplied to the desulfurization part 3.

The second reformer 8 is filled with a reforming catalyst. As this reforming catalyst, for example, an Al ₂ O ₃ (alumina) sphere surface impregnated with Ni and supported can be used. . The reforming catalyst is not limited to this, and any reforming catalyst that can perform partial oxidation reforming may be used. For example, Ru or Rh supported on zirconia or stabilized zirconia may be used. Alternatively, rhodium and at least one metal selected from Group VIII metals of the periodic table other than rhodium may be used which are supported on a carrier containing Al ₂ O ₃ (alumina) and zirconia.

  Further, in the solid oxide fuel cell system according to the present embodiment, a post-desulfurization source gas path 15 is provided between the desulfurization unit 3 and the second reformer 8, and this post-desulfurization source gas path 15 is provided. The raw material gas desulfurized through is supplied to the second reformer 8. Furthermore, a second reformed air path 13 is provided from the outside of the housing 7 toward the second reformer 8, and the air used for the partial oxidation reforming reaction through the second reformed air path 13. Is also configured to be supplied to the second reformer 8. Then, the second reformer 8 performs the partial oxidation reforming reaction shown in the above formula (3) using the supplied raw material gas and air. The second reformer 8 returns the reformed gas generated by the partial oxidation reforming reaction to the raw material gas path 1 on the upstream side of the booster 2 through the recycle path 19. By adopting such a configuration, it becomes possible to add hydrogen to the source gas flowing through the source gas path 1. For this reason, the desulfurization part 3 can perform hydrodesulfurization with respect to the raw material gas supplied using this added hydrogen.

  Note that a decompression unit 18 is provided in the recycling path 19. For this reason, when the pressure in the path of the recycle path 19 is high, the decompression unit 18 can reduce the reformed gas flowing in the path to a desired pressure. Then, the reformed gas lowered to a desired pressure is returned to the raw material gas path 1.

  As described above, in the solid oxide fuel cell system according to the present embodiment, the raw material gas desulfurized in the desulfurization unit 3 is divided, and the first reformer 4 and the second reformer 8 are respectively connected in parallel. It is the structure to distribute. The first reformer 4 efficiently generates reformed gas (fuel gas) used for power generation reaction from the desulfurized raw material gas by the steam reforming reaction, while the second reformer 8 performs partial oxidation reforming. Hydrogen required for hydrodesulfurization in the desulfurization section 3 can be generated by a quality reaction.

  For this reason, unlike the conventional solid oxide fuel cell system, it is not necessary to add water (reformed water) to the reformer in order to generate hydrogen used for hydrodesulfurization in the desulfurization section 3. Furthermore, the partial reforming reforming reaction is performed in the second reformer 8, and there is no concern that water (reformed water) is mixed with the reformed gas supplied to the desulfurization unit 3.

  Therefore, in the solid oxide fuel cell system according to the present embodiment, the amount of water (reformed water) supplied from the outside can be reduced. Further, as described above, the second reformer 8 is configured to perform the partial oxidation reforming reaction, and water (reformed water) is not used. It is possible to suppress the generation of dew condensation water in the recycle path 19 or the like through which the reformed gas flows. For this reason, it is possible to prevent the occurrence of problems such as water clogging in the recycling path 19. In this way, since water clogging can be prevented, pressure clogging occurs due to water clogging, and the flow of the reformed gas flowing through the recycle path 19 is deteriorated, and desulfurization is performed in the desulfurization section 3 to a desired sulfur concentration. It is possible to prevent the occurrence of a problem that it becomes impossible.

  Furthermore, in the solid oxide fuel cell system according to the present embodiment, hydrodesulfurization is performed in the desulfurization section 3 and the raw material gas from which the odorant or sulfur compound is removed is converted into the first reformer 4 and the second reformer. Can be supplied to the vessel 8. For this reason, deterioration of the reforming catalysts of the first reformer 4 and the second reformer 8 can be prevented, and the solid oxide fuel cell system can be operated with stable operation.

  Therefore, the solid oxide fuel cell system according to the present embodiment can reduce the amount of water to be supplied from the outside and can be operated efficiently and stably.

  In the solid oxide fuel cell system according to the present embodiment, as described above, the desulfurization section 3 is provided so as to be detachable. For this reason, when the reforming catalyst with which the desulfurization part 3 was filled by deterioration for a long time is deteriorated, the desulfurization part 3 can be easily replaced. For this reason, it is possible to prevent the overall performance of the solid oxide fuel cell system from being significantly lowered due to the deterioration of the reforming catalyst, and to allow the system to be operated for a long time.

(Modification 1)
Next, Modification 1 of the solid oxide fuel cell system according to the present embodiment will be described with reference to FIGS. 3 and 4 are schematic views showing an example of the configuration of a solid oxide fuel cell system according to Modification 1 of the present embodiment. FIG. 3 schematically shows a configuration when the solid oxide fuel cell system according to Modification 1 of the present embodiment is viewed from the side. In FIG. 4, the structure when the inside of the housing | casing 7 of the solid oxide fuel cell system which concerns on embodiment is seen from the top is shown typically. FIG. 5 is a diagram schematically showing an example of the configuration of the second reformer 8 provided in the solid oxide fuel cell system according to Modification 1 shown in FIGS. 3 and 4.

  Compared to the solid oxide fuel cell system according to the present embodiment described above, the air heat exchanger 5 and the second reformer 8 are adjacent to each other in the solid oxide fuel cell system according to the first modification. Differs in that they are arranged. For this reason, the same code | symbol is attached | subjected to the member similar to the solid oxide fuel cell system which concerns on this Embodiment, and the description shall be abbreviate | omitted.

  Here, the partial oxidation reforming reaction performed by the second reformer 8 is an exothermic reaction. For this reason, for example, when the solid oxide fuel cell system is enlarged, the flow rate of the raw material gas to be hydrodesulfurized in the desulfurization unit 3 increases. For this reason, in order to utilize for the hydrodesulfurization implemented by the desulfurization part 3, the flow volume of the reformed gas returned to the raw material gas path 1 through the recycle path | route 19 also increases. As described above, when a large amount of high-temperature reformed gas is circulated through the recycle path 19, the piping and the booster 2 that constitute the recycle path 19 are thermally deteriorated.

  Therefore, in the solid oxide fuel cell system according to the modified example 1, the second reformer 8 is disposed adjacent to the air heat exchanger 5, and the air flowing through the air heat exchanger 5 and the second reforming are arranged. The temperature of the reformed gas is lowered by exchanging heat with the vessel 8 and the recycle path 19 is circulated. Further, as shown in FIG. 5, the second reformer 8 includes a reforming catalyst filling unit 26 and a heat exchanging unit 27, thereby further exchanging heat with the air flowing through the air heat exchanger 5. Can be done efficiently.

  That is, in the second reformer 8, the reforming catalyst filling unit 26 is disposed on the upstream side where the raw material gas is supplied, and the heat exchange unit that performs heat exchange with the air heat exchanger 5 on the downstream side thereof. 27 is arranged. Then, the reformed gas that has been reformed after passing through the reforming catalyst filling unit 26 exchanges heat with the power generation air flowing through the air heat exchanger 5 when flowing through the heat exchanging unit 27, and the temperature is lowered. . The reformed gas whose temperature has been lowered is returned to the raw material gas path 1 through the recycle path 19. As a result, it is possible to prevent thermal degradation of the recycling path 19 and the booster 2.

  The air heat exchanger 5 recovers heat from the reformed gas by heat exchange with the reformed gas flowing through the second reformer 8, and generates power generation air flowing through the air heat exchanger 5. It is the structure which can be heated. In other words, the air heat exchanger 5 heats power generation air not only using the exhaust gas and radiant heat from the combustion unit 23 but also using heat generated by the partial oxidation reforming reaction performed by the second reformer 8. It is a configuration that can. Thus, since the air heat exchanger 5 can efficiently heat the power generation air, the heat generated by the partial oxidation reforming reaction performed in the second reformer 8 is not used for heating the power generation air. Compared with the configuration, the capacity of the air heat exchanger 5 itself can be reduced.

(Modification 2)
Next, Modification 2 of the solid oxide fuel cell system according to the present embodiment will be described with reference to FIG. FIG. 6 is a schematic diagram showing an example of the configuration of a solid oxide fuel cell system according to Modification 2 of the present embodiment. In FIG. 6, the structure when the solid oxide fuel cell system which concerns on the modification 2 of this Embodiment is seen from the side part is shown typically. The configuration of the solid oxide fuel cell system according to Modification 2 as viewed from above is the same as that of the solid oxide fuel cell system according to Modification 1 described above (FIG. 4).

  Compared to the solid oxide fuel cell system according to the present embodiment described above, the air heat exchanger 5 and the second reformer 8 are adjacent to each other in the solid oxide fuel cell system according to the second modification. Are different from each other in that the condenser 24 is provided in the recycling path 19. That is, the solid oxide fuel cell system according to Modification 2 has a configuration in which the condenser 24 is further provided in the configuration of the solid oxide fuel cell system according to Modification 1. For this reason, the same code | symbol is attached | subjected to the member similar to the solid oxide fuel cell system which concerns on this Embodiment, or the solid oxide fuel cell system which concerns on the modification 1, and the description shall be abbreviate | omitted.

  The condenser 24 is provided in the recycle path 19, and condenses moisture contained in the reformed gas flowing through the recycle path 19. The water obtained by condensation is stored in a drain tank (not shown). That is, the second reformer 8 is configured to perform partial oxidation reforming and generate reformed gas from the raw material gas. For this reason, the second reformer 8 contains much less moisture in the generated reformed gas than the reformer configured to generate the reformed gas by performing steam reforming, Still some water. Therefore, in the solid oxide fuel cell system according to Modification 2, the condenser 24 is provided, and even if the reformed gas flowing through the recycle path 19 is lowered in temperature, moisture is generated by the condenser 24. This moisture can be recovered. For this reason, it is possible to suppress problems such as water in the flow path (recycle path 19) due to condensed water, that is, corrosion and breakage of the pressure increasing unit 2.

  As described above, in the present embodiment, it is possible to provide a solid oxide fuel cell system that can reduce the amount of water to be supplied as reformed water and can be operated efficiently and stably. Is possible.

  From the above description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  In the solid oxide fuel cell system of the present invention, in order to supply a hydrogen-containing gas to a desulfurization section that performs hydrodesulfurization, a dedicated reformer (second reformer) for performing a partial oxidation reforming reaction is provided. Device). Therefore, it can be widely applied to fuel cell systems that remove sulfur components from raw material gas by hydrodesulfurization.

DESCRIPTION OF SYMBOLS 1 Raw material gas path | route 2 Pressure | voltage rise part 3 Desulfurization part 4 1st reformer 5 Air heat exchanger 6 Solid oxide fuel cell 7 Case 8 2nd reformer 9 Evaporator 10 Air supply path 11 Reformed water path 12 Reformed air path 13 Second reformed air path 14 First post-desulfurization source gas path 15 Second post-desulfurization source gas path 16 Fuel gas supply path 17 Air supply path 18 Decompression section 19 Recycle path 20 Exhaust gas path 22 Heat insulation section 23 Combustion Unit 24 condenser 26 reforming catalyst filling unit 27 heat exchange unit

Claims (6)

A solid oxide fuel cell that generates electricity by a power generation reaction using the supplied fuel and air; and
A combustion section for generating exhaust gas by burning unused fuel and air in the solid oxide fuel cell;
An air heat exchanger that heats the air supplied to the solid oxide fuel cell using heat of the exhaust gas;
A desulfurization section for removing sulfur components contained in the supplied raw material by hydrodesulfurization;
A first reformer that generates a reformed gas serving as the fuel from the raw material from which the sulfur component has been removed by the desulfurization unit;
A solid oxide comprising: a second reformer that reforms a part of the raw material from which the sulfur component has been removed by the desulfurization unit by a partial oxidation method and returns the obtained reformed gas to the upstream side of the desulfurization unit Fuel cell system.   The solid oxide fuel cell system according to claim 1, wherein the desulfurization unit is detachably provided on the solid oxide fuel cell system.   The solid oxide fuel cell system according to claim 1 or 2, wherein the first reformer includes an evaporator for vaporizing water supplied for use in a steam reforming reaction.   The air heat exchanger heats the air supplied to the solid oxide fuel cell by heat of the reformed gas generated by the second reformer in addition to heat of the exhaust gas. 4. The solid oxide fuel cell system according to any one of items 1 to 3.   The said 2nd reformer is arrange | positioned adjacent to the said air heat exchanger, and is provided with the heat exchange part which heat-exchanges between this air heat exchanger and the said reformed gas. Solid oxide fuel cell system. A pressurizing unit that pressurizes the raw material and supplies the raw material to the desulfurization unit;
A recycling path which is a path for guiding the reformed gas generated by the second reformer to the upstream side of the booster;
The solid oxide fuel cell according to any one of claims 1 to 5, further comprising a condenser provided in the recycling path and condensing moisture contained in fuel flowing through the recycling path. system.