JP2010212178A - Solid-oxide fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of soot at the time of combustion in a combustor in a solid-oxide fuel cell system which has the combustor and directly heats and raises the temperature of a fuel battery cell to a power generation temperature by a combustion gas of the combustor. <P>SOLUTION: The solid-oxide fuel cell system includes a solid-oxide fuel cell 3, a combustor 1 which is arranged at least on one of a fuel electrode side and an air electrode side of the cell 3, and a combustion container 16 which becomes a passage of the combustion gas 5 generated in the combustor 1, and raises the temperature of the cell 3 to a power generation temperature by the combustion gas 5. An evaporator 4 which generates steam 15 is installed in the combustion container 16, and the combustion gas 5 generated in the combustor 1 and the steam 15 generated in the evaporator 4 are mixed in the combustion container 16. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell system that is a kind of high-temperature fuel cell, and relates to a solid oxide fuel cell system including a combustor that directly heats a fuel cell with combustion gas to a power generation temperature and raises the temperature. .

  Patent Document 1 discloses a conventional example of a solid oxide fuel cell system including a combustor. A solid oxide fuel cell system according to Patent Document 1 will be described with reference to FIG. The solid oxide fuel cell system includes a combustor 1, an evaporator 4, a reformer 22, and a cell 3 of a solid oxide fuel cell. In order to reform the hydrocarbon-based fuel by the reformer 22, water is supplied to the evaporator 4 provided outside the combustor 1, the combustor 1 is burned to indirectly heat the evaporator 4, and the steam 15 Is generated. The generated steam 15 is supplied to the reformer 22, mixed with a hydrocarbon fuel, and steam reformed to generate a reformed gas 23. The generated reformed gas 23 is supplied to the cell 3 to start power generation. By providing the evaporator 4 in contact with the outside of the combustor 1, steam can be generated in a short time, and the startability of the reformer 22 and the solid oxide fuel cell can be improved.

JP 2007-31158 A

  In a solid oxide fuel cell system, in order to improve the startability, the method of heating the cell directly with the combustion gas of the combustor and raising the temperature causes the combustion state of the combustion gas to be uneven depending on the fuel supply state of the combustion gas. Thus, wrinkles may occur partially. When wrinkles occur, the wrinkles adhere to the cells, resulting in poor electrical insulation and deterioration of the cells.

  In general, it is known that a method of mixing water vapor with combustion gas is effective for preventing generation of soot due to combustion of combustion gas.

  However, in the conventional system according to Patent Document 1, an evaporator that generates water vapor is disposed outside the combustor, and the generated water vapor is guided to a reformer through a pipe. For this reason, water vapor and combustion gas generated in the combustor are separated and cannot be mixed, and soot generation cannot be prevented.

  In order to prevent the generation of soot during combustion in the combustor, the solid oxide fuel cell system according to the present invention basically has the following characteristics.

  A solid oxide fuel cell, a combustor disposed on at least one of the fuel electrode side and the air electrode side of the cell, and a combustion container serving as a flow path for combustion gas generated by the combustor, In the solid oxide fuel cell system in which the temperature of the cell is raised to the power generation temperature with the combustion gas, an evaporator for generating water vapor is provided in the combustion container, and the combustion gas generated from the combustor and generated from the evaporator Steam to be mixed is mixed in the combustion vessel.

  Preferably, the evaporator has a porous structure having pores.

  Further, in the solid oxide fuel cell system according to the present invention, the evaporator is a water channel provided around the flow path of the combustion gas in the combustion container, and the water channel and the cell are disposed in the combustion container. There may be provided a plate-like member for mixing the combustion gas and water vapor generated from the water channel.

  In the solid oxide fuel cell system according to the present invention, the evaporator may include a nozzle header and a spray nozzle that is attached to the nozzle header and discharges mist water to generate water vapor.

  According to the present invention, an evaporator for generating water vapor is installed in a combustion container, and the evaporator is heated with combustion gas generated by the combustor and water vapor is generated. Thereby, it becomes possible to mix combustion gas and water vapor | steam, and can prevent generation | occurrence | production of soot.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram of the solid oxide fuel cell system by Example 1 of this invention. The block diagram of the solid oxide fuel cell system by Example 2 of this invention. The block diagram of the solid oxide fuel cell system by Example 3 of this invention. The block diagram of the solid oxide fuel cell system by a prior art. 1 is a schematic diagram of an evaporator in Embodiment 1. FIG. In Example 1, the block diagram of a solid oxide fuel cell system at the time of providing an evaporator in the combustion container by the side of an air electrode. In Example 1, the block diagram of a solid oxide fuel cell system at the time of providing the evaporator in the combustion container of both the fuel electrode side and the air electrode side. In Example 3, the top view which looked at the combustion container from the upper part in order to demonstrate arrangement | positioning of a nozzle header and a spray nozzle.

In the solid oxide fuel cell system according to the present invention, the temperature of the cells of the solid oxide fuel cell is raised to the power generation temperature with the combustion gas generated by the combustor. And the following means are used in order to prevent the generation of soot during combustion in the combustor.
(1) An evaporator is installed in a combustion vessel that becomes a flow path of combustion gas generated by the combustor, and water vapor is generated.
(2) The combustion gas generated in the combustor and the water vapor from the evaporator are mixed uniformly.
(3) Water vapor mixed with the combustion gas is generated in a short time.

  In order to prevent the generation of soot, it is necessary to mix water vapor with the combustion gas. Therefore, an evaporator is installed in a combustion vessel that becomes a flow path of the combustion gas generated in the combustor, and the evaporator is heated with the combustion gas from the combustor to generate water vapor, thereby generating the combustion gas and water vapor. Are mixed in the combustion container.

  At this time, a hole is provided in the evaporator to form a porous structure, or a water channel is provided around the flow path of the combustion gas in the combustion container as an evaporator, and combustion gas and water vapor are provided between the water channel and the cell. By providing a baffle plate for mixing or using a spray that discharges mist water and generates water vapor as an evaporator, combustion gas and water vapor can be mixed uniformly, and water vapor can be mixed more It can be generated in a short time. Further, when the evaporation surface of the water vapor of the evaporator is exposed in the combustion gas flow path, the water vapor can be generated in the combustion container more efficiently.

  Thereby, combustion gas and water vapor can be mixed uniformly immediately after the start of combustion, and soot generation at the time of combustion can be prevented.

  FIG. 1 shows an embodiment of a solid oxide fuel cell system according to the present invention. In the solid oxide fuel cell system of this embodiment, power generation air 12 is supplied from the air pipe 11 and power generation fuel 14 is supplied from the fuel pipe 13 to generate power in the cell 3 of the solid oxide fuel cell. The side of the cell 3 to which the power generation air 12 is supplied is referred to as the air electrode side, and the side to which the power generation fuel 14 is supplied is referred to as the fuel electrode side. In this embodiment, the combustor and the combustion container 16 are provided on both the fuel electrode side and the air electrode side of the cell 3. The combustion container 16 has a function for preheating the fuel and air supplied to the cells of the solid oxide fuel cell with the combustion gas, in addition to the flow path of the combustion gas generated by the combustor.

  When generating electric power, the combustion fuel 6 and the combustion air 7 are supplied to the combustor 1 and burned, and the generated combustion gas 5 raises the temperature of the cell 3 to the power generation temperature. As the combustion fuel 6, a hydrocarbon fuel such as methane can be used. Thereafter, power generation air 12 and power generation fuel 14 are supplied to the cell 3 to start power generation. Since the exhaust gas 10 after power generation is hot, it is exhausted after heat recovery. Further, since the power generation temperature of the solid oxide fuel cell is as high as about 800 ° C., the periphery of the cell 3 is surrounded by a heat insulating material 9 to suppress heat dissipation.

  In the embodiment shown in FIG. 1, the evaporator 4 is provided in the combustion gas flow path between the combustor 1 and the cell 3 in the combustion container 16 on the fuel electrode side, and the combustion gas 5 is used as the evaporator 4. Is heated directly. The evaporator 4 is connected to a water pump 8 and is supplied with water. This water is evaporated by heating the combustion gas 5 to become water vapor 15.

  The evaporator 4 in the present embodiment has a shape as shown in FIG. 5, can store water that becomes the water vapor 15, and has a porous structure in which a large number of holes 2 are open. Further, the evaporator 4 has an evaporation surface of water exposed in the flow path of the combustion gas, so that the water vapor 15 can be generated in the combustion container 16 efficiently and uniformly in a short time.

  The combustion gas 5 from the combustor 1 rises toward the cell 3 through the air holes 2 of the evaporator 4. At this time, the water vapor 15 generated from the evaporator 4 and the combustion gas 5 are uniformly mixed. Thereby, it becomes possible to prevent the generation of soot during combustion of the combustor 1.

  In addition, since the evaporator 4 has a porous structure, the heat transfer area of the evaporator 4 is increased, and water vapor can be generated in a shorter time. Therefore, a soot generation preventing effect can be expected immediately after the combustion of the combustor 1.

  Note that the number, size, and arrangement of the holes 2 are not limited to the example of FIG. If the holes 2 are finely and uniformly distributed in the evaporator 4, the combustion gas 5 and the water vapor 15 can be mixed more uniformly, which is more effective in preventing soot generation.

  The material of the evaporator 4 is not particularly limited as long as it is heat-resistant (for example, metal, ceramic, glass, etc.) and does not generate impurities (for example, organic materials). Further, the size of the evaporator 4 is desirably a size (area) that covers the combustor 1 in consideration of uniformly mixing the water vapor with the combustion gas and considering the generation efficiency of the water vapor. In the present embodiment, the shape of the evaporator 4 is a quadrangle as shown in FIG. 5, but is not limited to this, and may be a circle, for example.

  In the present embodiment, the combustor 1 and the combustion container 16 are provided on both the fuel electrode side and the air electrode side of the cell 3, but may be provided on only one of them. Also in the following embodiments, the combustor 1 and the combustion container 16 may be provided on either or both of the fuel electrode side and the air electrode side. However, as in the present embodiment, the fuel electrode side and the air electrode side are provided. The case where it installs in both is demonstrated.

  Further, in this embodiment, the evaporator 4 is provided in the combustion container 16 on the fuel electrode side, but may be provided in the combustion container 16 on the air electrode side as shown in FIG. As described above, the combustion chambers 16 on both the fuel electrode side and the air electrode side may be provided. Also in the following embodiments, the evaporator 4 may be provided on either or both of the fuel electrode side and the air electrode side as long as the combustor 1 is installed. The case where it installs in the combustion container 16 of the side is demonstrated.

  FIG. 2 shows another embodiment of the solid oxide fuel cell system according to the present invention. 2, the same reference numerals as those in the first embodiment (FIG. 1) denote the same or corresponding elements as those in the first embodiment.

  In this embodiment, a water channel 17 is provided as an evaporator in the combustion vessel 16 on the fuel electrode side. The water channel 17 is installed in the combustion container 16 so as to go around the combustion gas flow channel, and is connected to the water pump 8 to supply water. Similarly to the evaporator 4 of the first embodiment, the water channel 17 which is the evaporator of the present embodiment also exposes the evaporation surface of water in the flow path of the combustion gas 5, so that the water vapor 15 can be efficiently transferred into the combustion container 16. Can be generated.

  Further, in the solid oxide fuel cell system of the present embodiment, a baffle plate 18 is provided between the water channel 17 serving as an evaporator and the cell 3 in the combustion container. The baffle plate 18 is a plate-like member for changing the flow of the combustion gas 5 and the water vapor 15 generated from the water channel 17 and mixing them uniformly. The baffle plate 18 is not a material that generates impurities (such as an organic material) as in the evaporator 4 of the first embodiment, and any material may be used as long as it is heat resistant such as metal, ceramic, glass, and the like. The size (area) is preferably larger than the cross-sectional area of the cell chamber in which the cell 3 is stored. Further, the shape of the baffle plate 18 may be, for example, a square or a circle, and is not particularly limited.

  The water supplied from the water pump 8 to the water channel 17 becomes the water vapor 15 when the combustion container 16 is heated by the combustion gas 5 and rises toward the cell 3 together with the combustion gas 5 generated in the combustor 1. The rising steam 15 collides with the baffle plate 18 to change the flow direction, and is uniformly mixed with the rising combustion gas 5. Thereby, it becomes possible to prevent the generation of soot during combustion of the combustor 1.

  If the water depth of the water channel 17 is reduced or the width is reduced, the generation time of the water vapor 15 is shortened, which is effective in preventing soot generation immediately after the combustion of the combustor 1. The water channel 17 does not necessarily go around the periphery of the combustion container 16, but in consideration of the generation efficiency of steam and the uniformity of distribution, the water channel 17 is preferably arranged around the periphery or an arrangement close thereto. A plurality of water channels 17 may be provided around the inside of the combustion container 16.

  Further, by providing protrusions or holes on the surface of the baffle plate 18, the combustion gas 5 and the water vapor 15 can be mixed more uniformly, further improving the effect of preventing soot generation. It becomes possible to make it.

  FIG. 3 shows another embodiment of the solid oxide fuel cell system according to the present invention. 3, the same reference numerals as those in the first embodiment (FIG. 1) denote the same or corresponding elements as those in the first embodiment.

  In this embodiment, a nozzle header 21 and a spray nozzle 19 are provided as evaporators in the combustion gas flow path between the combustor 1 and the cell 3 in the combustion vessel 16 on the fuel electrode side. . A plurality of spray nozzles 19 are attached to the nozzle header 21 toward the combustor 1 and are connected to the water pump 8 to supply water.

  The water supplied from the water pump 8 to the nozzle header 21 becomes mist 20 from the spray nozzle 19 and is discharged toward the combustor 1. The mist 20 is fine mist-like water droplets, is heated by the combustion gas 5 generated in the combustor 1 and rising toward the cell 3, becomes water vapor, collides with the combustion gas 5, and is uniformly mixed. Thereby, generation | occurrence | production of soot at the time of combustion of the combustor 1 can be prevented.

  In addition, by using the spray nozzle 19 that can generate finer mist 20, the time during which the mist 20 becomes water vapor can be further shortened, and an effect of preventing soot generation can be expected immediately after combustion of the combustor 1.

  The arrangement of the nozzle header 21 and the spray nozzle 19 in the combustion container 16 will be described with reference to FIG. FIG. 8 is a plan view of the combustion container 16 as viewed from above, and only the nozzle header 21 and the spray nozzle 19 are shown in a simplified manner.

  A plurality of nozzle headers 21 (three in FIG. 8) are installed, and a plurality of spray nozzles 19 (six in FIG. 8) are attached to each. Each nozzle header 21 is connected to the water pump 8 and supplied with water. As described above, by installing the plurality of spray nozzles 19 in each of the plurality of nozzle headers 21, the combustion gas 5 and water vapor can be uniformly mixed. It is desirable that the spray nozzles 19 be mounted in a uniform distribution in the combustion vessel 16 so that the discharged mist is efficiently and uniformly converted into water vapor.

  The spray nozzle 19 and the nozzle header 21 are not particularly limited as long as the spray nozzle 19 and the nozzle header 21 are heat resistant so as not to generate impurities, like the evaporator 4 of the first embodiment and the baffle plate 18 of the second embodiment.

  The size and number of the nozzle header 21 and the spray nozzle 19 are not limited to the example of FIG. 8 as long as the water vapor can be uniformly distributed over a wide range in the combustion container 16. In consideration of uniformly mixing the water vapor with the combustion gas 5 and the generation efficiency of the water vapor, it is desirable to install the plurality of spray nozzles 19 so as to cover the combustor 1 as a whole.

  The shapes of the nozzle header 21 and the spray nozzle 19 are not particularly limited. For the nozzle header 21, for example, if the shape is cylindrical, a plurality of spray nozzles 19 can be attached in the circumferential direction. If it does in this way, the effect of uniform mixing can further be raised, mixing of the combustion gas 5 and water vapor | steam will be accelerated | stimulated, and the soot generation | occurrence | production prevention effect will further improve.

  The present invention can be applied to a solid oxide fuel cell system including a combustor for raising the temperature of a fuel cell to a power generation temperature.

  DESCRIPTION OF SYMBOLS 1 ... Combustor, 2 ... Hole, 3 ... Cell, 4 ... Evaporator, 5 ... Combustion gas, 6 ... Combustion fuel, 7 ... Combustion air, 8 ... Water pump, 9 ... Thermal insulation, 10 ... Exhaust gas, DESCRIPTION OF SYMBOLS 11 ... Air piping, 12 ... Air for electric power generation, 13 ... Fuel piping, 14 ... Fuel for electric power generation, 15 ... Water vapor, 16 ... Combustion container, 17 ... Water channel, 18 ... Baffle plate, 19 ... Spray nozzle, 20 ... Mist, 21 ... Nozzle header, 22 ... Reformer, 23 ... Reformed gas.

Claims (5)

A solid oxide fuel cell, a combustor disposed on at least one of the fuel electrode side and the air electrode side of the cell, and a combustion container serving as a flow path of combustion gas generated by the combustor, In the solid oxide fuel cell system that raises the temperature of the cell to the power generation temperature with the combustion gas,
A solid oxide fuel cell characterized in that an evaporator for generating water vapor is provided in the combustion container, and combustion gas generated from the combustor and water vapor generated from the evaporator are mixed in the combustion container. system.   2. The solid oxide fuel cell system according to claim 1, wherein the evaporator has a porous structure having pores.   2. The solid oxide fuel cell system according to claim 1, wherein the evaporator is a water channel provided around the flow path of the combustion gas in the combustion container, and the water channel and the cell are formed in the combustion container. A solid oxide fuel cell system comprising a plate-like member for mixing the combustion gas and water vapor generated from the water channel.   2. The solid oxide fuel cell system according to claim 1, wherein the evaporator includes a nozzle header and a spray nozzle that is attached to the nozzle header and discharges mist water to generate water vapor. Fuel cell system.   2. The solid oxide fuel cell system according to claim 1, wherein the evaporator has a water vapor evaporation surface exposed in the combustion gas flow path.

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