JP2014107220A - Solid oxide type fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide type fuel cell system capable of preventing high temperature deterioration of auxiliary device and/or piping due to the heat of reformed gas flowing through a recycle path.SOLUTION: The solid oxide type fuel cell system includes: a desulfurizer 3 that removes a sulfur component contained in a material gas by means of hydrogen desulfurization; a first reformer 4 that reforms the material gas from the desulfurizer 3 by means of moisture reforming reaction; a reforming water reservoir 29 that reserves reforming water used for the moisture reforming reaction in the first reformer 4; an evaporator 9 that evaporates the reforming water supplied from the reforming water reservoir 29; a solid oxide type fuel cell 6 that generates the power using the reformed gas from the first reformer 4 as the fuel; and a recycle path 19 for feeding a part of the reformed gas from the first reformer 4 to a material gas path. The reforming water in the reforming water reservoir 29 exchanges the heat with the reformed gas flowing through the recycle path 19.

Description

  The present invention relates to a solid oxide fuel cell system including a desulfurizer 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 raw material gas, for example, steam reforming using steam is used to reform the raw material 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 the steam reforming catalyst from deteriorating, a desulfurization apparatus (desulfurizer) that reduces odorants or sulfur compounds 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).

  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 booster 111 through the recycle gas supply path 113. An improved 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 cell system of Patent Document 2, the water mixed by 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, in the conventional solid oxide fuel cell system, the thermal influence on auxiliary equipment, piping and the like due to the heat of the reformed gas flowing through the recycling path has not been sufficiently studied.

  The present invention has been made in view of such circumstances, and compared with the prior art, a solid oxide fuel cell system that can suppress high-temperature deterioration of auxiliary equipment, piping, and the like due to the heat of reformed gas flowing through a recycling path I will provide a.

  A solid oxide fuel cell system according to the present invention includes a booster for boosting a raw material gas, a desulfurizer for removing sulfur components contained in the raw material gas from the booster by hydrodesulfurization, and the desulfurizer. A first reformer that reforms the raw material gas by a steam reforming reaction, a reforming water storage unit that stores reforming water used for the steam reforming reaction in the first reformer, and the reforming An evaporator that evaporates the reformed water supplied from the water reservoir, a solid oxide fuel cell that generates electricity using the reformed gas from the first reformer as fuel, and a modification from the first reformer. A recycle path for sending a part of the quality gas to the raw material gas path upstream of the booster, and the reformed water in the reformed water storage section is heated with the reformed gas and the heat flowing through the recycle path. Exchange.

  The solid oxide fuel cell system according to the present invention is configured as described above, and can suppress high-temperature deterioration of auxiliary equipment, piping, and the like due to the heat of the reformed gas flowing through the recycle path, as compared with the prior art.

1 is a schematic diagram illustrating an example of a configuration of a solid oxide fuel cell system according to Embodiment 1. FIG. 1 is a schematic diagram illustrating an example of a configuration of a solid oxide fuel cell system according to Embodiment 1. FIG. 6 is a schematic diagram illustrating an example of a configuration of a solid oxide fuel cell system according to Embodiment 2. FIG. 6 is a schematic diagram illustrating an example of a configuration of a solid oxide fuel cell system according to Embodiment 2. FIG. 6 is a schematic diagram showing an example of the configuration of a solid oxide fuel cell system according to Modification 1 of Embodiment 1. FIG. 6 is a schematic diagram illustrating an example of a configuration of a solid oxide fuel cell system according to Modification 2 of Embodiment 1. FIG. 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.

  The present invention provides the following aspects.

  A solid oxide fuel cell system according to a first aspect of the present invention includes a desulfurizer for removing sulfur components contained in a raw material gas by hydrodesulfurization, and reforming the raw material gas from the desulfurizer by a steam reforming reaction. A first reformer that performs, a reforming water reservoir that stores reforming water used in the steam reforming reaction in the first reformer, and an evaporation that evaporates the reforming water supplied from the reforming water reservoir. , A solid oxide fuel cell that generates electricity using the reformed gas from the first reformer as fuel, and a recycling path for sending a part of the reformed gas from the first reformer to the raw material gas path The reformed water in the reformed water storage section exchanges heat with the reformed gas flowing through the recycling path.

  According to the above configuration, the reformed gas can be cooled to an appropriate temperature by heat exchange between the reformed gas flowing through the recycling path and the reformed water in the reformed water storage unit. Therefore, it is possible to suppress high-temperature deterioration of auxiliary equipment, piping, and the like due to the heat of the reformed gas flowing through the recycling path, as compared with the conventional case. Further, the reformed water can be preheated to an appropriate temperature by the above heat exchange. Therefore, the load on the evaporator is reduced and the evaporator can be downsized. In addition, the heat recovery of the solid oxide fuel cell system can be made more efficient.

  A solid oxide fuel cell system according to a second aspect of the present invention includes a desulfurizer for removing sulfur components contained in a raw material gas by hydrodesulfurization, and a steam reforming reaction for a part of the raw material gas from the desulfurizer. The first reformer reformed by the above, the reformed water storage section for storing the reformed water used for the steam reforming reaction in the first reformer, and the reformed water supplied from the reformed water storage section An evaporator to be evaporated, a solid oxide fuel cell that generates electricity using the reformed gas from the first reformer as a fuel, and a second reformer that reforms a part of the raw material gas from the desulfurizer by a partial oxidation reaction And a recycle path for sending the reformed gas from the second reformer to the raw material gas path, and the reformed water in the reformed water storage section exchanges heat with the reformed gas flowing through the recycle path. .

  According to the above configuration, the first reformer efficiently generates the reformed gas used for the power generation reaction from the desulfurized source gas by the steam reforming reaction, while the second reformer desulfurizes by the partial oxidation reaction. Hydrogen required for hydrodesulfurization in the reactor can be generated. Therefore, 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 desulfurizer.

  Moreover, similarly to the first aspect, it is possible to suppress high-temperature deterioration of auxiliary equipment, piping, and the like due to the heat of the reformed gas flowing through the recycling path, as compared with the conventional case. Further, the load on the evaporator is reduced, and the evaporator can be downsized. In addition, the heat recovery of the solid oxide fuel cell system can be made more efficient. In particular, since the reformed gas in the partial oxidation reaction becomes higher in temperature than the steam reforming reaction, the reformed gas cooling and reformed water preheating are performed in the first reformer and the second reformer as in this embodiment. This is useful in a configuration that uses a mass organ.

A solid oxide fuel cell system according to a third aspect of the present invention includes, in the first aspect or the second aspect, a booster that boosts the feed gas in the feed gas path and supplies the boosted gas to the desulfurizer. The reformed gas in the recycle path is sent to the source gas path upstream of the booster.
According to the above configuration, the reformed water in the reformed water reservoir exchanges heat with the reformed gas flowing through the recycle path, as in the first and second aspects. Therefore, even when the reformed gas is sent to the raw material gas flow path upstream of the booster, it is possible to suppress high-temperature degradation of the booster due to the heat of the reformed gas, as compared with the conventional case.

  A solid oxide fuel cell system according to a fourth aspect of the present invention includes at least a reformer and a solid oxide fuel cell according to any one of the first aspect, the second aspect, and the third aspect. And a heat insulating portion disposed on the inner wall of the housing, and at least a part of the reformed water storage portion is installed in the heat insulating portion.

  According to said structure, at least one part of the reforming water storage part is covered with the heat insulation part. Therefore, the heat dissipation of the reforming water in the reforming water reservoir can be suppressed.

  A solid oxide fuel cell system according to a fifth aspect of the present invention is the reformed gas flowing through the recycle path in any one of the first aspect, the second aspect, the third aspect, and the fourth aspect. A condenser for condensing water vapor.

  According to said structure, since the water vapor | steam in reformed gas is removed by the condensation in a condenser, the dew condensation water production | generation by the condensation of the water vapor | steam in reformed gas is suppressed in the recycle path | route downstream of a condenser. Therefore, it is possible to suppress the blockage of the recycling path due to condensed water, the failure of auxiliary equipment, and the like. In particular, in this aspect, since the condenser is arranged downstream of the reforming water reservoir, the temperature of the reformed gas can be lowered by heat exchange with the reforming water, and the water vapor in the reformed gas is sufficient. Can be removed.

  Hereinafter, Embodiments 1 and 2 and Modifications 1 and 2 that are specific examples of the first to fifth aspects 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.

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

  As shown in FIGS. 1 and 2, the solid oxide fuel cell system includes a raw material gas path 1, a desulfurizer 3, a first reformer 4, an air heat exchanger 5, a solid oxide fuel cell 6, and an evaporation. 9, air path 10, reformed water path 11, first reformed air path 12, post-desulfurization source gas path 14, fuel gas supply path 16, air supply path 17, decompression unit 18, recycle path 19, exhaust gas path 20 The heat insulation part 22 and the combustion part 23 are housed inside the housing 7. Further, the solid oxide fuel cell system has a configuration in which the booster 2 and the reformed water storage unit 29 are arranged outside the housing 7.

  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 present embodiment, the gas supplied from the outside through the raw material gas path 1 is referred to as a raw material gas (raw material), and the sulfur component is removed from the raw material gas and is reformed by the reforming reaction in the first reformer 4. The reformed gas may be referred to as fuel gas (fuel).

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.
A heat insulating portion 22 made of a heat insulating material is disposed on the inner wall of the housing 7. Thereby, the heat dissipation from the inside of the housing | casing 7 to the exterior is suppressed appropriately.

The booster 2 pressurizes the source gas in the source gas path 1 and supplies it to the desulfurizer 3.
The booster 2 is disposed outside the housing 7 so as not to be easily affected by the high-temperature heat of the housing 7. As the booster 2, for example, a constant displacement pump such as a diaphragm is used, but is not limited thereto.

  In addition, as source gas, gas which has hydrocarbons, such as city gas, natural gas, and LPG, as a main component is used, for example.

The desulfurizer 3 removes sulfur components contained in the raw material gas by a hydrodesulfurization method. Here, the desulfurizer 3 is disposed at a substantially central portion of the upper wall of the casing 7. Further, at least a part of the desulfurizer 3 is covered with the heat insulating portion 22. Thereby, the heat release from the desulfurizer 3 can be prevented and the desulfurizer 3 can be prevented from being directly exposed to the heat in the housing 7. Furthermore, since the desulfurizer 3 is covered by the heat insulating portion 22, the temperature distribution in the desulfurizer 3 can be made as uniform as possible to suppress variations. Therefore, the temperature of the desulfurizer 3 can be easily controlled.
Examples of the desulfurizing agent filled in the desulfurizer 3 include a desulfurizing agent containing copper and zinc (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 desulfurizer 3 hydrocrackes organic sulfur in the raw material gas in a temperature range of 350 to 400 ° C. Then, the desulfurizer 3 removes the generated H ₂ S by adsorbing it to ZnO in 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. This DMS is removed by the desulfurization agent 3 in the desulfurizer 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).

When a desulfurizing agent containing copper and zinc is used, the desulfurizer 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 desulfurizer 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 desulfurizer 3 as described above is supplied to the first reformer 4 through the raw material gas path 14 after desulfurization.

  The first reformer 4 reforms the raw material gas passed through the desulfurizer 3 by a steam reforming reaction. That is, it is advantageous that the first reformer 4 has a specification capable of performing a steam reforming reaction in order to realize a highly efficient operation. Therefore, as shown in FIG. 1, in the present embodiment, an evaporator 9 is disposed upstream of the first reformer 4, and water supplied through the reformed water path 11 is mixed with the desulfurized raw material gas in the first. The reformer 4 is 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, at the time of starting the solid oxide fuel cell system, the first reformer 4 has insufficient heat energy to perform the steam reforming reaction which is an endothermic reaction. Therefore, the first reformer 4 may be configured to perform not only the steam reforming reaction but also the partial oxidation reaction. Then, when starting the solid oxide fuel cell system, the first reformed air path 12 is used for the first modification without supplying water from the reformed water path 11 to the first reformer 4 (evaporator 9). Using the air introduced into the mass device 4, the first reformer 4 performs a partial oxidation reaction represented by the following formula (3) to generate hydrogen gas and carbon monoxide.
_{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 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 becomes 400 degreeC or more, for example, it will become possible to perform the steam reforming reaction represented 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 reaction represented by the formula (3), the steam reforming reaction represented by the above-described formula (4) increases the 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. In addition, since the steam reforming reaction shown in the equation (4) is an endothermic reaction, the amount of heat generated by the partial oxidation reaction shown in the equation (3), the heat held by the exhaust gas discharged from the combustion unit 23, and the heat from the combustion unit 23 Utilizing radiant heat, the steam reforming reaction proceeds while supplementing the necessary amount of heat. Then, if the temperature of the first reformer 4 is, for example, 600 ° C. or higher, the amount of heat necessary for the steam reforming reaction of the formula (4) can be supplemented only with the heat of the exhaust gas and the radiant heat from the combustion unit 23. Therefore, it is possible to switch to the operation of only the steam reforming reaction.

  The evaporator 9 evaporates the reformed water supplied from the reformed water storage unit 29. That is, the evaporator 9 is installed to perform the steam reforming reaction in the first reformer 4. In the evaporator 9, the water supplied from the reforming water path 11 is vaporized using the heat of the exhaust gas discharged from the combustion unit 23 and the radiant heat from the combustion unit 23, and after desulfurization supplied from the desulfurizer 3. The raw material gas is mixed. 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 at a position facing the combustion unit 23. The air heat exchanger 5 heats air (power generation air) supplied from the outside through the air 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. Although details will be described later, the exhaust gas from which part of the heat held by the heat exchange with the air is removed by the air heat exchanger 5 is guided to the desulfurizer 3 through the exhaust gas path 20. Yes.

  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 composed of zirconia doped with yttria (YSZ), zirconia doped with yttrium or scandium, or a lanthanum gallate solid electrolyte is used. Can be used. 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.

  The combustion unit 23 generates exhaust gas by burning unused fuel and air in the solid oxide fuel cell 6. In addition, the exhaust gas path 20 through which the exhaust gas flows is arranged in the heat insulating portion 22 and configured to reduce heat radiation from the exhaust gas path 20 as much as possible.

  By the way, regarding the flow rate and temperature of the exhaust gas generated in the combustion unit 23, the fuel utilization rate of the fuel gas and air (power generation air) in the solid oxide fuel cell 6 (the solid oxide fuel cell as fuel by the power generation reaction) It is possible to control by adjusting the ratio consumed at 6). For example, the fuel utilization rate of the fuel gas and air in the solid oxide fuel cell 6 is set so that the temperature range of the combustion unit 23 is about 600 to 900 ° C.

  In the present embodiment, the exhaust gas first heats the first reformer 4. Thereby, a part of the heat of the exhaust gas is consumed. Next, the air heat exchanger 5 is heated by the exhaust gas in which part of the heat is consumed. Due to the heat exchange between the air and the exhaust gas by the air heat exchanger 5, the heat of the exhaust gas is further removed, and the temperature is lowered to an appropriate temperature for heating the desulfurizer 3. The exhaust gas whose temperature has been lowered in this way flows through the exhaust gas path 20 and is supplied to the desulfurizer 3.

  That is, the temperature of the exhaust gas generated in the combustion unit 23 is as high as about 600 ° C. to 900 ° C., for example. However, if the first reformer 4 is heated by the exhaust gas, and heat exchange with the air is further performed by the air heat exchanger 5, and the air is heated, the temperature of the exhaust gas decreases until the exhaust gas path 20 is reached. To do. In particular, when generating power of 1 kW using the solid oxide fuel cell 6, for example, it is necessary to heat air of 50 L / min or more from the outside air temperature to about 400 to 800 ° C. The container 5 requires a large amount of heat. Therefore, this necessary amount of heat is covered by the amount of heat of the exhaust gas.

  As described above, the temperature of the exhaust gas flowing through the exhaust gas path 20 is absorbed by the flow rate and temperature of the exhaust gas generated in the combustion unit 23, the amount of heat absorbed by the first reformer 4, and the air heat exchanger 5. It is controlled to take a desired value in consideration of the amount of heat. Then, the exhaust gas that has reached the exhaust gas path 20 circulates in the path and flows to the desulfurizer 3.

  When the desulfurizer 3 is filled with a desulfurizing agent containing copper and zinc (for example, Patent Document 3), it is generated in the combustion unit 23 so that the exhaust gas temperature when reaching the desulfurizer 3 is about 150 to 350 ° C. The flow rate and temperature of the exhaust gas to be adjusted, the amount of heat absorbed by the first reformer 4, the amount of heat absorbed by the air heat exchanger 5, and the like are adjusted. In this way, the desulfurizer 3 is set to a temperature (150 to 300 ° C.) suitable for hydrodesulfurization.

  In addition, when the desulfurizer 3 is filled with a desulfurization agent that is a combination of a Ni—Mo or Co—Mo catalyst and zinc oxide, the exhaust gas temperature when reaching the desulfurizer 3 is about 350 to 450 ° C. In addition, the flow rate and temperature of the exhaust gas generated in the combustion unit 23, the amount of heat absorbed by the first reformer 4, and the amount of heat absorbed by the air heat exchanger 5 are adjusted. In this manner, the desulfurizer 3 is similarly set to a temperature (350 to 400 ° C.) suitable for hydrodesulfurization.

  As described above, by installing the desulfurizer 3 in the exhaust gas path 20, the desulfurizer 3 can be set to a desired temperature suitable for hydrodesulfurization.

  The recycle path 19 is a flow path for sending the reformed gas from the first reformer 4 to the raw material gas path 1.

  In the present embodiment, the fuel gas supply path 16 toward the solid oxide fuel cell 6 is branched in the middle, and a part of the reformed gas supplied from the first reformer 4 is upstream of the booster 2. A recycling path 19 is formed so as to be sent to the source gas path 1. For this reason, it becomes possible to add hydrogen to the raw material gas which distribute | circulates the raw material gas path | route 1 and is supplied to the desulfurizer 3, and the desulfurizer 3 performs the above-mentioned hydrodesulfurization using this hydrogen. It is configured to be able to.

  A decompression unit 18 is provided in the vicinity of the branch point between the fuel gas supply path 16 and the recycle path 19 and in the recycle path 19. The decompression unit 18 adjusts the flow rate of the reformed gas flowing through the recycle path 19 and can be realized by, for example, a capillary tube. That is, the decompression unit 18 is configured so that the reformed gas flows through the recycle path 19 by a desired flow rate by narrowing the flow path with a capillary tube or the like and increasing the pressure loss.

The reformed water storage unit 29 stores the reformed water used for the steam reforming reaction in the first reformer 4. In the reformed water storage unit 29, water from the reformed water path 11 is temporarily stored as reformed water, and the recycle path 19 passes through the reformed water storage unit 29 and is supplied from the booster 2. Also communicates with the upstream source gas path 1. As a result, the reformed water in the reformed water storage section exchanges heat with the reformed gas flowing through the recycle path 19, and the reformed gas cooled by the heat exchange is sent to the raw material gas path 1 and preheated by the heat exchange. The reformed water is supplied to the evaporator 9. That is, the high temperature reformed gas functions as a heating fluid in the main heat exchange, and the low temperature reformed water functions as a heat receiving fluid in the main heat exchange. For example, when the piping constituting the recycling path 19 is submerged in the reforming water in the reforming water storage unit 29, the reformed gas flowing in the piping and the reforming water in the reforming water storage unit 29 exchange heat. To do.
With the above configuration, in this embodiment, the reformed gas can be cooled to an appropriate temperature by heat exchange between the high-temperature reformed gas flowing through the recycling path 19 and the low-temperature reformed water in the reformed water storage unit 29. High-temperature deterioration of the booster 2 (an example of an auxiliary device) and piping (for example, a joint material of piping) due to the heat of the reformed gas can be suppressed.

  Moreover, in this embodiment, since reformed water can be preheated to appropriate temperature by said heat exchange, the load of the evaporator 9 decreases and the evaporator 9 can be reduced in size. In addition, the heat recovery of the solid oxide fuel cell system can be made more efficient.

(Embodiment 2)
A solid oxide fuel cell system according to Embodiment 2 will be described with reference to FIGS. 3 and 4. 3 and 4 are schematic views showing an example of the configuration of the solid oxide fuel cell system according to Embodiment 2. FIG. In FIG. 3, the structure when the solid oxide fuel cell system according to Embodiment 2 is viewed from the side is schematically shown. In FIG. 4, the structure when the inside of the housing | casing of the solid oxide fuel cell system which concerns on Embodiment 2 is seen from the top is shown typically.

  As shown in FIGS. 3 and 4, the solid oxide fuel cell system includes a raw material gas path 1, a desulfurizer 3, a first reformer 4, an air heat exchanger 5, a solid oxide fuel cell 6, 2 reformer 8, evaporator 9, air path 10, reformed water path 11, first reformed air path 12, second reformed air path 13, first post-desulfurization source gas path 14A, second post-desulfurization source The gas path 14 </ b> B, the fuel gas supply path 16, the air supply path 17, the decompression section 18, the recycle path 19, the exhaust gas path 20, the heat insulation section 22, and the combustion section 23 are configured to be housed inside the housing 7. Further, the solid oxide fuel cell system has a configuration in which the booster 2 and the reformed water storage unit 29 are arranged outside the housing 7.

  Raw material gas path 1, booster 2, desulfurizer 3, first reformer 4, air heat exchanger 5, solid oxide fuel cell 6, evaporator 9, air path 10, reformed water path 11, first Since the reformed air path 12, the fuel gas supply path 16, the air supply path 17, the decompression section 18, the recycle path 19, the exhaust gas path 20, the heat insulation section 22 and the combustion section 23 are the same as those in the first embodiment, description thereof is omitted. To do. That is, the solid oxide fuel cell system according to the present embodiment is different from the first embodiment in that the second reformer 8 is provided separately from the first reformer 4 described above.

  In the present embodiment, similarly to the first embodiment, the gas supplied from the outside through the raw material gas path 1 is referred to as a raw material gas (raw material), and the sulfur component is removed from the raw material gas. The reformed gas reformed by the quality reaction may be referred to as fuel gas (fuel). However, 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. To do.

  The second reformer 8 reforms a part of the raw material gas from the desulfurizer 3 by a partial oxidation reaction. That is, in order to supply hydrogen for hydrodesulfurization performed in the desulfurization unit 3 to the desulfurizer 3, a reformed gas (hydrogen-containing gas) is generated by a partial oxidation reaction. The feed gas path 1 is configured to be sent through the recycle path 19. Thereby, hydrogen can be added to the raw material gas supplied to the desulfurizer 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 may be any reforming catalyst that can perform partial oxidation. 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 present embodiment, the second post-desulfurization source gas path 14B is provided between the desulfurizer 3 and the second reformer 8, and the source gas desulfurized through the second post-desulfurization source gas path 14B The second reformer 8 is configured to be supplied. In addition, a second reformed air path 13 is provided from the outside of the housing 7 toward the second reformer 8, and the partial oxidation reaction air passes through the second reformed air path 13 to the second reformed air. It is configured to be supplied to the mass device 8. The second reformer 8 performs the partial oxidation reaction shown in the above formula (3) using the supplied raw material gas and air. The second reformer 8 sends the reformed gas generated by this partial oxidation reaction to the raw material gas path 1 upstream 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 desulfurizer 3 can perform hydrodesulfurization with respect to the raw material gas supplied using this added hydrogen. As described above, in the solid oxide fuel cell system of the present embodiment, the raw material gas desulfurized by the desulfurizer 3 is divided and distributed to the first reformer 4 and the second reformer 8 in parallel. It is a configuration. Thus, 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. Hydrogen necessary for hydrodesulfurization in the desulfurizer 3 can be generated by the reaction. Therefore, 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 desulfurizer 3.
In the present embodiment, similarly to the first embodiment, the reformed gas is cooled to an appropriate temperature by heat exchange between the high-temperature reformed gas flowing through the recycle path 19 and the low-temperature reformed water in the reformed water storage unit 29. Therefore, it is possible to suppress high-temperature deterioration of the booster 2 (an example of an auxiliary device) and piping (for example, a joint material of piping) due to the heat of the reformed gas. Further, since the reformed water can be preheated to an appropriate temperature by the above heat exchange, the load on the evaporator 9 is reduced and the evaporator 9 can be downsized. In addition, the heat recovery of the solid oxide fuel cell system can be made more efficient.

  In particular, since the reformed gas in the partial oxidation reaction becomes higher in temperature than the steam reforming reaction, the reformed gas cooling and reformed water preheating are performed in the first reformer 4 and the first reformer as in the present embodiment. This is useful in a configuration in which two reformers 8 are used in combination.

(Modification 1)
A solid oxide fuel cell system according to Modification 1 of Embodiment 1 will be described with reference to FIG. FIG. 5 is a schematic diagram illustrating an example of a configuration of a solid oxide fuel cell system according to Modification 1 of Embodiment 1.

  As shown in FIG. 5, the solid oxide fuel cell system includes a raw material gas path 1, a desulfurizer 3, a first reformer 4, an air heat exchanger 5, a solid oxide fuel cell 6, an evaporator 9, Air path 10, reformed water path 11, first reformed air path 12, post-desulfurization source gas path 14, fuel gas supply path 16, air supply path 17, decompression unit 18, recycle path 19 </ b> A, exhaust gas path 20, reforming The water storage unit 29 </ b> A, the heat insulating unit 22, and the combustion unit 23 are housed inside the housing 7. The solid oxide fuel cell system has a configuration in which the booster 2 is disposed outside the housing 7.

  Raw material gas path 1, desulfurizer 3, first reformer 4, air heat exchanger 5, solid oxide fuel cell 6, evaporator 9, air path 10, reformed water path 11, first reformed air path 12, the desulfurized raw material gas path 14, the fuel gas supply path 16, the air supply path 17, the decompression section 18, the exhaust gas path 20, the booster 2, the heat insulation section 22, and the combustion section 23 are the same as those in the first embodiment. Is omitted. That is, this modification differs from the first embodiment in that at least a part of the reformed water storage unit 29A is installed in the heat insulating unit 22.

  In the example shown in FIG. 5, the reformed water storage unit 29A is disposed in the heat insulating unit 22, and the recycling path 19A from the decompression unit 18 extends through the heat insulating unit 22 and the reformed water storage unit 29A. Therefore, the reformed water can be preheated to an appropriate temperature by heat exchange between the high temperature reformed gas flowing through the recycling path 19A and the low temperature reformed water in the reformed water storage unit 29A. Moreover, since the reforming water storage part 29A is covered with the heat insulating part 22, the heat radiation of the reforming water in the reforming water storage part 29A can be suppressed.

  5 illustrates an example in which the reformed water storage unit 29A of the solid oxide fuel cell system according to the first embodiment is disposed in the heat insulating unit 22, but the solid oxide fuel cell system according to the second embodiment may have the same configuration. The reformed water storage unit 29 may be disposed in the heat insulating unit 22 as in the present modification.

(Modification 2)
A solid oxide fuel cell system according to Modification 2 of Embodiment 1 will be described with reference to FIG. FIG. 6 is a schematic diagram illustrating an example of a configuration of a solid oxide fuel cell system according to Modification 2 of Embodiment 1.

  As shown in FIG. 6, the solid oxide fuel cell system includes a raw material gas path 1, a desulfurizer 3, a first reformer 4, an air heat exchanger 5, a solid oxide fuel cell 6, an evaporator 9, Air path 10, reformed water path 11, first reformed air path 12, post-desulfurization source gas path 14, fuel gas supply path 16, air supply path 17, decompression unit 18, recycle path 19 </ b> A, exhaust gas path 20, reforming The water storage unit 29 </ b> A, the heat insulating unit 22, and the combustion unit 23 are housed inside the housing 7. The solid oxide fuel cell system has a configuration in which the condenser 24 and the booster 2 are disposed outside the housing 7.

  Raw material gas path 1, desulfurizer 3, first reformer 4, air heat exchanger 5, solid oxide fuel cell 6, evaporator 9, air path 10, reformed water path 11, first reformed air path 12, post-desulfurization source gas path 14, fuel gas supply path 16, air supply path 17, decompression section 18, recycle path 19A, exhaust gas path 20, booster 2, reforming water storage section 29A, heat insulation section 22 and combustion section 23 Since is the same as that of the first modification, the description thereof is omitted. That is, this modification differs from Modification 1 in that it further includes a condenser 24.

  The condenser 24 condenses the water vapor in the reformed gas flowing through the recycle path 19A. Specifically, the condenser 24 is provided in the recycling path 19A on the downstream side of the reforming water storage unit 29A. As a result, water vapor in the reformed gas can be removed by condensation in the condenser 24, and therefore, in the recycle path 19A downstream of the condenser 24, generation of condensed water due to condensation of water vapor in the reformed gas is suppressed. Accordingly, blockage of the recycling path 19A due to condensed water, failure of the booster 2, and the like can be suppressed. In particular, in the present modification, the condenser 24 is disposed downstream of the reforming water reservoir 29A, so that the temperature of the reforming gas can be lowered by heat exchange with the reforming water, Water vapor can be removed sufficiently.

  The water removed by the condensation in the condenser 24 may be drained to the outside from the recycling path 19A, but such water is recovered and reused as the reforming water in the reforming water storage unit 29A. May be. As a result, the amount of water to be supplied from the outside as the reformed water can be reduced, and the solid oxide fuel cell system can be operated efficiently and stably.

  FIG. 6 illustrates an example in which the condenser 24 is arranged in the solid oxide fuel cell system according to the first embodiment. However, the same condensation as in the present modification is applied to the solid oxide fuel cell system according to the second embodiment. A vessel may be placed.

  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.

  For example, in the first and second embodiments and the first and second modifications, the desulfurizer 3 is disposed in the heat insulating portion 22 that is located above and opposite to the combustion portion 23 (that is, the substantially central portion of the upper wall of the casing 7). An example where is arranged. However, the arrangement position of the desulfurizer is not limited to this position. For example, the desulfurizer may be arranged in the heat insulating portion 22 below the side surface of the housing 7. However, since the exhaust gas is diffused and guided almost uniformly above the combustion section 23, the temperature distribution of the radiant heat is made substantially uniform on the upper wall of the housing 7. Therefore, it is advantageous to dispose the desulfurizer on the upper wall of the casing 7 because the temperature distribution of the desulfurizer due to radiant heat can be made uniform.

  In addition, when the desulfurization agent of the desulfurizer 3 deteriorates after a long operation of the solid oxide fuel cell system, the performance of the solid oxide fuel cell system is degraded. Therefore, the desulfurizer 3 may be configured to be detachable from the casing 7 by appropriate detachment means. As a result, the solid oxide fuel cell system can be operated for a long time only by replacing the desulfurizer 3 in which the desulfurizing agent has deteriorated with a new desulfurizer.

  The present invention can suppress high-temperature deterioration of auxiliary equipment, piping, and the like due to the heat of the reformed gas flowing through the recycle path, as compared with the prior art. Therefore, this invention can be utilized for a solid oxide fuel cell system, for example.

1 Raw material gas path 2 Booster 3 Desulfurizer 4 First reformer 5 Air heat exchanger 6 Solid oxide fuel cell 7 Case 8 Second reformer 9 Evaporator 10 Air path 11 Reformed water path 12 First 1 reformed air path 13 2nd reformed air path 14 raw gas path 16 after desulfurization fuel gas supply path 17 air supply path 18 decompression part 19 recycle path 20 exhaust gas path 22 heat insulation part 23 combustion part 24 condenser 29 storage of reformed water Part

Claims (5)

A desulfurizer for removing sulfur components contained in the raw material gas by hydrodesulfurization, a first reformer for reforming the raw material gas from the desulfurizer by a steam reforming reaction, and the first reformer. A reforming water storage section for storing reforming water used for the steam reforming reaction, an evaporator for evaporating the reforming water supplied from the reforming water storage section, and a reformed gas from the first reformer A solid oxide fuel cell that generates electricity using as a fuel, and a recycling path for sending a part of the reformed gas from the first reformer to the raw material gas path,
A solid oxide fuel cell system in which the reformed water in the reformed water storage section exchanges heat with the reformed gas flowing through the recycling path. A desulfurizer for removing sulfur components contained in the raw material gas by hydrodesulfurization, a first reformer for reforming a part of the raw material gas from the desulfurizer by a steam reforming reaction, and the first reforming A reforming water storage section for storing reforming water used for the steam reforming reaction in the steam generator, an evaporator for evaporating the reforming water supplied from the reforming water storage section, and the first reformer A solid oxide fuel cell that generates electricity using the reformed gas as a fuel, a second reformer that reforms a part of the raw material gas from the desulfurizer by a partial oxidation reaction, and a A recycling path for sending the reformed gas to the raw material gas path,
A solid oxide fuel cell system in which the reformed water in the reformed water storage section exchanges heat with the reformed gas flowing through the recycling path. A pressure booster for boosting the feed gas in the feed gas path and supplying the desulfurizer;
The solid oxide fuel cell system according to claim 1 or 2, wherein the reformed gas in the recycling path is sent to the source gas path upstream of the booster.   The housing further includes at least the reformer and the solid oxide fuel cell, and a heat insulating portion disposed on an inner wall of the housing, and at least a part of the reforming water storage portion includes the heat insulating portion. The solid oxide fuel cell system according to any one of claims 1 to 3, wherein the solid oxide fuel cell system is installed in the unit. The solid oxide fuel cell system according to claim 1, further comprising a condenser that condenses water vapor in the reformed gas flowing through the recycling path.

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