JP2015105788A - Burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burner capable of changing an opening area of a nozzle depending on actuation conditions of a fuel cell without adding a movable valve.SOLUTION: A nozzle 63 injecting a combustible fluid into a combustion chamber 623 formed in a burner tile 62 includes a cylindrical member 631 in which a communication hole 631a communicating with the combustion chamber 623 is formed; and a shaft member 632 for forming a first injection passage 63b including a first injection port 63a at least a part of which is positioned in the communication hole 631a and that injects the combustible fluid into the combustion chamber 623. Furthermore, the cylindrical member 631 is formed out of a material higher in coefficient of thermal expansion than the shaft member 632.

Description

  The present invention relates to a combustion apparatus applied to a fuel cell.

  This type of combustion device burns a small amount of city gas (external flammable gas) as a flammable fluid in the combustion chamber immediately after the start of the fuel cell, and a large flow rate discharged from the fuel cell during operation of the fuel cell. Exhaust fuel (internal combustible gas) is burned in the combustion chamber as a combustible fluid. In addition, since the unreacted fuel gas which was not utilized for electric power generation in the fuel cell 10 remains in the exhaust fuel discharged | emitted from a fuel cell, it can utilize as a combustible fluid. Further, the discharged fuel is discharged from the fuel cell and has a temperature closer to the temperature inside the fuel cell than the external flammable gas at room temperature.

  Here, when the external combustible gas having a small flow rate is burned in the combustion device, if the diffusibility of the external combustible gas in the combustion chamber of the combustion device is poor, carbon monoxide ( There is a risk that the amount of CO) emissions will increase.

  For this reason, when burning a small amount of external combustible gas in the combustion device, the opening area of the nozzle that injects the combustible gas into the combustion chamber so that the external combustible gas is injected into the combustion chamber at high speed Need to be small. In addition, when a small flow rate of external combustible gas is injected into the combustion chamber at a high speed, the diffusibility of the external combustible gas in the combustion chamber is improved, so carbon monoxide (CO) emissions due to incomplete combustion are suppressed. It becomes possible.

  On the other hand, when a large flow of internal flammable gas is introduced into the combustion chamber of the combustion device, the pressure loss generated in the flow path of the internal flammable gas in the combustion device becomes significantly larger as the flow rate of the internal flammable gas increases. This makes it impossible to introduce a desired internal combustible gas into the combustion chamber.

  For this reason, when burning a large flow of internal combustible gas in the combustion device, the opening area of the nozzle that injects the combustible gas into the combustion chamber so that the internal combustible gas is injected into the combustion chamber at a low speed Need to be larger. Note that when a large flow of internal combustible gas is injected at a low speed, the pressure loss in the flow path of the internal combustible gas is reduced, so that a desired internal combustible gas can be introduced into the combustion chamber.

  As described above, the combustion apparatus applied to the fuel cell is required when starting the fuel cell (reducing the nozzle opening area) and during the operation of the fuel cell (increasing the nozzle opening area). Each needs to be satisfied.

  As a combustion apparatus that satisfies both of the requirements, for example, a configuration in which a movable valve for adjusting an opening area of a nozzle is added, such as a burner proposed in Patent Document 1, can be considered. According to this, by changing the opening area of the nozzle when the fuel cell is started by the movable valve and increasing the opening area of the nozzle during the power generation of the fuel cell, it is possible to realize a change in flow velocity according to the operating condition of the fuel cell. .

Special table 2001-501294 gazette

  However, when a movable valve that adjusts the opening area of the nozzle is added to the combustion apparatus, there is a problem that the number of parts of the combustion apparatus increases. An increase in the number of parts of the combustion device is not preferable because it increases the cost of the combustion device.

  In addition, when a movable valve is added to the combustion device, a gap is set between the movable valve and the surrounding members so that the movable valve and the surrounding members do not interfere with each other. There is a problem that the possibility of leaking to the outside increases. Note that leakage of the flammable fluid to the outside is not preferable because it causes a reduction in safety.

  An object of the present invention is to provide a combustion device that can change the opening area of a nozzle according to the operating conditions of a fuel cell without adding a movable valve.

  In order to achieve the above object, the present inventors have made extensive studies. As a result, the inventors have noticed that the temperature of the combustible fluid introduced into the combustion device is different at the time of starting and during the operation of the fuel cell, and the nozzles according to the temperature of the combustible fluid introduced into the combustion device. The composition which changes the opening area of was devised.

  The present invention is applied to a fuel cell (10) that outputs electric energy by an electrochemical reaction between a fuel gas and an oxidant gas. The first combustible fluid is combusted when the fuel cell is started, and the fuel cell is operated during the operation of the fuel cell. The present invention is intended for a combustion apparatus that burns a second combustible fluid having a temperature higher than that of the first combustible fluid.

  In the first aspect of the present invention, a refractory member (62) in which a combustion chamber (623) for burning each combustible fluid is formed, and a nozzle (63) for injecting each combustible fluid to the combustion chamber. The nozzle is provided between the cylindrical member (631) in which the communication hole (631a) communicating with the combustion chamber is formed, and at least a part of the nozzle is positioned inside the communication hole and between the inner surface of the communication hole. And a shaft member (632) forming a first injection passage (63b) having a first injection port (63a) for injecting each flammable fluid into the combustion chamber, and the tubular member is more heated than the shaft member. It is characterized by being composed of a material having a high expansion coefficient.

  According to this, during operation of the fuel cell that injects the second combustible fluid, which is higher in temperature than the first combustible fluid, into the combustion chamber, compared to when the fuel cell that injects the first combustible fluid into the combustion chamber is started. In addition, the opening area of the first injection port can be enlarged.

  Explaining this point, as the temperature of the combustible fluid flowing through the first injection passage rises, the nozzle expands so that the shaft member approaches the inner surface of the communication hole, and the cylindrical member reduces the inner diameter of the communication hole. Inflates to expand. At this time, since the cylindrical member is made of a material having a higher thermal expansion coefficient than that of the shaft member, the cylindrical member and the shaft member are adapted to increase in temperature of the combustible fluid flowing through the first injection passage. The gap between them, that is, the passage sectional area of the first injection passage and the opening area of the first injection port are enlarged.

  Thus, the combustion apparatus of the present invention uses the difference in thermal expansion between the cylindrical member and the shaft member constituting the nozzle, so that the opening of the nozzle can be adjusted according to the operating conditions of the fuel cell without using a movable valve. The area can be changed. As a result, a small flow rate of the first combustible fluid is injected into the combustion chamber at a high speed when the fuel cell is started, and a large flow rate of the second combustible fluid is injected into the combustion chamber at a low speed during operation of the fuel cell. It becomes possible.

  Here, “when the fuel cell is activated” means a preparation period before power generation in the fuel cell. Further, “during fuel cell operation” means a period during which the fuel cell is maintained in a power generation enabled state, and includes not only a period during which the fuel cell is generating power but also a period during which power generation is stopped.

  In addition, the code | symbol in the parenthesis of each means described in this column and the claim shows an example of a correspondence relationship with the specific means described in the embodiment described later.

1 is a schematic configuration diagram of a fuel cell system including a combustion apparatus according to a first embodiment. It is a block diagram which shows the internal structure of the combustion apparatus which concerns on 1st Embodiment. It is a characteristic view which shows the flow velocity change with respect to the flow rate change at the time of using a fixed nozzle. It is explanatory drawing for demonstrating the opening area of the nozzle at the time of fuel cell starting. It is explanatory drawing for demonstrating the opening area of the nozzle during a fuel cell driving | operation. It is a block diagram of the nozzle of the combustion apparatus which concerns on 2nd Embodiment. It is VII-VII sectional drawing of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. Note that, in each of the following embodiments, parts that are the same as or equivalent to the matters described in the preceding embodiment are denoted by the same reference numerals, and the description thereof may be omitted. Moreover, in each embodiment, when only a part of the component is described, the component described in the preceding embodiment can be applied to the other part of the component.

(First embodiment)
In this embodiment, as shown in FIG. 1, the combustion apparatus of the present invention is applied to a fuel cell system having a fuel cell 10 that outputs electric energy by an electrochemical reaction between a fuel gas and an oxidant gas (air in this embodiment). An example to which 6 is applied will be described.

The fuel cell 10 is composed of a solid oxide fuel cell (SOFC) whose operating temperature is high (approximately 800 ° C.). In the fuel cell 10, hydrogen and oxygen electrochemical reactions represented by the following reaction formulas [F1] and [F2], and carbon monoxide (CO) and oxygen electrochemical reactions represented by the reaction formulas [F3] and [F4] Thus, electric energy is output.
^{_{(Anode) 2H 2 + 2O 2- → 2H}} 2 O + 4e - ... [F1]
(Cathode) O ₂ + 4e ⁻ → 2O ² −... [F2]
_{^{(Anode) 2CO + 2O 2- → 2CO 2}} + 4e - ... [F3]
(Cathode) O ₂ + 4e ⁻ → 2O ² −... [F4]
The fuel cell 10 includes an air supply pipe 3 forming an oxidant gas supply path, a fuel supply pipe 4 forming a fuel gas supply path, an air discharge pipe 6a forming an exhaust air discharge path, and a discharge containing fuel gas. A fuel discharge pipe 6b forming a fuel discharge path is connected.

  The air supply pipe 3 includes, in order from the upstream side, a filter 31 that removes dust, dust, and the like, an air blower 32 that pumps air, and combustion gas that is generated by the combustion device 6 that will be described later. First and second air preheaters 33 and 34 are provided for heating by heat exchange.

  The fuel supply pipe 4 includes, in order from the upstream side, a desulfurizer 41 that removes sulfur components contained in a fuel gas raw material (combustible gas such as city gas), a fuel blower 42 that pumps the raw material, and a fuel preheater 43. A fuel reformer 44 is provided.

  The fuel preheater 43 heats the fuel gas raw material pumped from the fuel blower 42 by exchanging heat with the combustion gas generated by the combustion device 6. The fuel preheater 43 is also connected to the water supply path 5 and functions as a water vapor generator that evaporates water supplied from the water pump 52 via the pure water device 51 by heat exchange with the combustion gas. Plays.

  The fuel reformer 44 heats the mixed gas obtained by mixing the fuel gas heated by the fuel preheater 43 and the steam with the combustion gas and heats it, and also contains hydrogen and carbon monoxide by steam reforming. It is a fuel gas generator that generates gas. Note that the fuel reformer 44 is not limited to steam reforming, and for example, partial oxidation reforming may be performed when the fuel cell 10 is started.

  Each discharge pipe 6a, 6b is connected to a combustion apparatus 6 that generates high-temperature combustion gas. Further, in the fuel discharge pipe 6b of the present embodiment, in order to stabilize the combustion of the combustion device 6 when the fuel cell 10 is started up, the fuel gas raw material bypasses the fuel reformer 44, the fuel cell 10 and the like. A bypass pipe 6c to be introduced into the combustion device 6 is connected.

  The combustion device 6 combusts the fuel gas raw material introduced through the bypass pipe 6c when starting the fuel cell as a “first combustible fluid”, and discharges fuel (exhaust gas containing fuel gas) during operation of the fuel cell 10. Gas) as a “second combustible fluid”.

  In the combustion device 6, a fuel gas raw material at a normal temperature (for example, 25 ° C.) is introduced at a small flow rate when the fuel cell is started, and a high-temperature (for example, 700 ° C.) exhaust fuel is discharged at a large flow rate during operation of the fuel cell 10. be introduced. Hereinafter, the raw material of the fuel gas introduced into the combustion device 6 and the discharged fuel may be referred to as a combustible fluid.

  A combustion gas discharge pipe 7 for discharging high-temperature combustion gas generated inside is connected to the combustion device 6. The combustion gas discharge pipe 7 is connected to devices such as a fuel reformer 44, a second air preheater 34, a fuel preheater 43, and a first air preheater 33 in order from the upstream side in order to effectively use the combustion heat of the combustion gas. It is connected.

  The above is the schematic configuration of the fuel cell system of the present embodiment, and details of the combustion device 6 will be described below with reference to FIG. FIG. 2 is a configuration diagram showing an internal configuration of the combustion device 6, and shows an axial cross section of the combustion device 6.

  The combustion apparatus 6 of the present embodiment includes a metal casing 61, a burner tile 62 having fire resistance, and a nozzle 63 for injecting a flammable fluid as main components.

  The casing 61 is made of a metal material having a high heat resistance temperature such as stainless steel. Specifically, the casing 61 of the present embodiment is configured by a hollow container having a rectangular parallelepiped appearance, and includes a bottom plate 61a, a side plate 61b, and a top plate (not shown) serving as a base. In the present embodiment, in order to ensure the sealing performance in the casing 61, for example, the side plate 61b and the top plate are joined together by dense metal welding having the same thermal expansion coefficient.

  A fuel introducing portion 611 for introducing a combustible fluid into the inside is formed on the bottom plate 61a of the casing 61. The fuel introduction part 611 constitutes a connection part for connecting the fuel discharge pipe 6b.

  A plurality of oxidant gas introduction portions 612 for introducing an oxidant gas such as exhaust air into the inside are formed on the lower side in the vertical direction of the side plate 61 b of the casing 61. The oxidant gas introduction part 612 constitutes a connection part for connecting the air discharge pipe 6a. The side plate 61b of the casing 61 is provided with a plug insertion portion (not shown) for inserting a spark plug (not shown) that electrically generates a spark to ignite the combustible fluid.

  The top plate of the casing 61 is formed with a combustion gas discharge portion (not shown) for discharging combustion gas. This combustion gas discharge part constitutes a connection part for connecting the combustion gas discharge pipe 7.

  Subsequently, the burner tile 62 is a “refractory member” that is disposed inside the casing 61 and protects the casing 61 from high-temperature combustion gas. The burner tile 62 is made of a material having excellent fire resistance such as zirconia or alumina.

  The burner tile 62 of this embodiment is disposed so as to oppose the fuel introduction part 611 and the oxidant gas introduction part 612 in the casing 61 and occupy the lower space inside the casing 61. It is desirable that at least a part of the burner tile 62 be separated from the casing 61 so as to absorb a difference in thermal expansion from the casing 61.

  Specifically, the burner tile 62 of the present embodiment is formed of a cylindrical body whose outer shell has a rectangular parallelepiped shape, and a combustion chamber 623 in which a combustible fluid and an oxidant gas are mixed and burned is formed. ing. This combustion chamber 623 has a tapered shape in which a cross-sectional area is enlarged upward (from the bottom plate 61a side of the casing 61 to the top plate) in consideration of the mixing property of the flammable fluid and the oxidant gas. Yes.

  The burner tile 62 has a cylindrical storage space 624 for storing a nozzle 63 described later on the bottom side thereof, and an oxidant from each oxidant gas introduction portion 612 of the casing 61 to the combustion chamber 623 on the side surface thereof. An oxidant gas flow path 625 that guides gas is formed. The oxidant gas flow path 625 is such that the direction of air introduction into the combustion chamber 623 and the central axis of the combustion chamber 623 is such that the oxidant gas swirls and flows along the inner surface (tapered surface) of the combustion chamber 623. It is desirable to have a flow path configuration that does not intersect.

  In addition, the burner tile 62 is provided with an attachment portion (not shown) for attaching an ignition plug (not shown). In the present embodiment, the spark plug is attached to the burner tile 62.

  Subsequently, the nozzle 63 injects a flammable fluid into the combustion chamber 623 inside the burner tile 62, and is accommodated in the accommodation space 624 of the burner tile 62. The nozzle 63 of the present embodiment includes a cylindrical member 631 in which a communication hole 631 a communicating with the combustion chamber 623 is formed, and a shaft member 632 positioned inside the communication hole 631 a of the cylindrical member 631. FIG. 2 illustrates an example in which the entire shaft member 632 is disposed inside the communication hole 631a. However, the shaft member 632 is configured such that a part of the shaft member 632 is positioned inside the communication hole 631a. Also good.

  The cylindrical member 631 of the present embodiment is configured in a cylindrical shape, and is joined to the bottom plate 61 a of the casing 61 by welding or the like in a state where the outer wall surface is separated from the burner tile 62. The cylindrical member 631 is disposed in the accommodation space 624 so that the central axis thereof coincides with the central axis of the combustion chamber 623.

  The shaft member 632 is a member having a circular cross section that extends in the central axis direction of the communication hole 631a. The shaft member 632 of the present embodiment includes a dish part 632a formed on the upper end side in the axial direction, a body part 632b formed on the lower end side in the axial direction, and an intermediate part 632c that connects the dish part 632a and the body part 632b. Have

  The dish portion 632a has a disk shape with an outer diameter smaller than the inner diameter of the communication hole 631a so that an annular gap is formed between the cylindrical member 631 and the communication hole 631a. A gap formed between the outer surface in the radial direction of the dish portion 632a and the inner surface in the radial direction of the communication hole 631a constitutes a first injection passage 63b that injects the combustible fluid into the combustion chamber 623. And the opening part opened to the combustion chamber 623 side in the 1st injection path 63b comprises the 1st injection port 63a.

  The trunk portion 632b has a cylindrical shape so that the outer diameter thereof is the same as or slightly larger than the inner diameter of the communication hole 631a of the cylindrical member 631. The shaft member 632 is fixed to the tubular member 631 by press-fitting the body portion 632b into the communication hole 631a of the tubular member 631 (gap fitting). The shaft member 632 may be fixed to the bottom 61a of the casing 61 instead of the cylindrical member 631.

  The intermediate part 632c has a cylindrical shape whose outer diameter is smaller than the outer diameter of the dish part 632a. The shaft member 632 has an outer diameter that increases in the order of the intermediate part 632c → the dish part 632a → the trunk part 632b.

  Further, the shaft member 632 communicates with the first communication passage 632d communicating with the fuel introduction portion 611 formed in the bottom plate 61a of the casing 61, and the second communication passage 632d communicating with the communication hole 631a of the cylindrical member 631 and the first communication passage 632d. A communication path 632e is formed. The first communication path 632 d is configured by a bottomed hole extending in the axial direction of the shaft member 632, and the second communication path 632 e is configured by a through hole extending in the radial direction of the shaft member 632.

  Here, as described in [Background Art], the combustion apparatus 6 applied to the fuel cell 10 is required to start the fuel cell 10 (reducing the opening area of the nozzle 63), It is necessary to satisfy each requirement during operation (increasing the opening area of the nozzle 63).

  FIG. 3 shows an application range (a lower limit value and an upper limit value) of the volume flow rate of the combustible fluid introduced into the combustion chamber 623 and the flow rate of the combustible fluid when starting the fuel cell 10 and during operation of the fuel cell 10. The following range is shown. Note that “when the fuel cell 10 is activated” shown on the horizontal axis of FIG. 3 indicates the minimum flow rate of the combustible fluid required when the fuel cell 10 is activated, and “when the fuel cell 10 is operating” Shows the maximum flow rate of combustible fluid required during operation.

  In the combustion device 6, as shown in FIG. 3, the flow rate of the combustible fluid is within the applicable range with respect to the change in the volume flow rate of the combustible fluid both at the start of the fuel cell 10 and during the operation of the fuel cell 10. It is necessary to set the opening area of the nozzle 63 so as to change. The upper limit value of the flow velocity application range is set in consideration of the pressure loss of the flammable fluid during operation of the fuel cell 10, and the lower limit value is set in consideration of the diffusibility of the flammable fluid when the fuel cell 10 is started up. Is set.

  Here, in the fuel cell system, immediately after the start of the fuel cell 10, the fuel gas raw material is burned in the combustion chamber 623 as the first combustible fluid, and discharged fuel (fuel remaining in the discharged fuel) during operation of the fuel cell 10. Gas) is combusted in the combustion chamber 623 as a second combustible fluid.

  At this time, the flow rate of the combustible fluid introduced into the combustion chamber 623 during operation of the fuel cell 10 is several tens of times the flow rate of the combustible fluid introduced into the combustion chamber 623 when the fuel cell 10 is started.

  In contrast, the flow rate of the combustible fluid introduced into the combustion chamber 623 during operation of the fuel cell 10 is hundreds of times the volume flow rate of the combustible fluid introduced into the combustion chamber 623 when the fuel cell 10 is started. Sometimes.

  As described above, a fixed nozzle in which the opening area of the first injection port 63a of the nozzle 63 is fixed is adopted for the fuel cell 10 that is required to change the volume flow rate significantly compared to the flow rate of the flammable fluid. Then, it is difficult to change the flow velocity within the applicable range according to the volume flow rate of the combustible fluid.

  For example, when the opening area of the fixed nozzle is set small so that the flow rate near the lower limit is obtained with respect to the minimum flow rate of the combustible fluid at the time of starting the fuel cell 10 (see the white circle in FIG. 3), the operation of the fuel cell 10 is performed. The flow rate with respect to the volume flow rate of the flammable fluid in the inside greatly exceeds the upper limit value (see the black circle in FIG. 3).

  Conversely, if the opening area of the fixed nozzle is set large so that a flow velocity near the upper limit is obtained with respect to the maximum flow rate of the combustible fluid during operation of the fuel cell 10 (see the black square in FIG. 3), the fuel cell 10. The flow velocity with respect to the volume flow rate of the flammable fluid at the time of start-up falls below the lower limit value (see the white square in FIG. 3).

  In addition, when the cylindrical member 631 and the shaft member 632 of the nozzle 63 are formed of the same material having the same thermal expansion coefficient, the opening area of the first injection port 63a of the nozzle 63 is hardly changed, and similarly to the fixed nozzle, It is difficult to change the flow rate of the flammable fluid within the applicable range.

  Therefore, in this embodiment, the opening area of the first injection port 63a is cylindrical so that the flow rate of the combustible fluid changes within an appropriate range when the fuel cell 10 is started and during operation. The coefficients of thermal expansion of the member 631 and the shaft member 632 are set.

Specifically, the cylindrical member 631 of the present embodiment is made of a material having a higher coefficient of thermal expansion than the shaft member 632. That is, in this embodiment, the shaft member 632 is made of a material having a low coefficient of thermal expansion (for example, Al ₂ O ₃ , heat coefficient of thermal expansion: 7.0 × 10 ⁻⁶ [/ ° C.]), and the cylindrical member 631 is formed. It is made of a material having a high coefficient of thermal expansion (for example, SUS301S, coefficient of thermal expansion: 19.1 × 10 ⁻⁶ [/ ° C.]).

  The nozzle 63 of the present embodiment expands so that the shaft member 632 approaches the inner surface of the communication hole 631a as the temperature of the combustible fluid flowing through the first injection passage 63b increases, and the cylindrical member 631 becomes the communication hole. It expand | swells so that the internal diameter of 631a may be expanded.

  At this time, since the cylindrical member 631 is made of a material having a higher coefficient of thermal expansion than the shaft member 632, the cylindrical member 631 and the cylindrical member 631 are arranged in accordance with an increase in the temperature of the combustible fluid flowing through the first injection passage 63b. A gap between the shaft member 632 is enlarged.

  In other words, the nozzle 63 of the present embodiment has the first injection passage when the high temperature exhaust fuel flows through the first injection passage 63b as compared with when the low temperature fuel gas material flows through the first injection passage 63b. The passage sectional area of 63b and the opening area of the first injection port 63a are enlarged.

  This point will be described with reference to FIGS. FIG. 4 is a top view and an axial cross-sectional view of the nozzle 63 at the time of startup of the fuel cell 10 in which the raw material for the low-temperature fuel gas flows through the first injection passage 63b. FIG. 5 is a top view and an axial cross-sectional view of the nozzle 63 during operation of the fuel cell 10 in which high-temperature exhaust fuel flows through the first injection passage 63b.

  In the nozzle 63 of the present embodiment, when high-temperature exhaust fuel flows through the first injection passage 63b, the outer diameter d1 of the plate portion 632a of the shaft member 632 shown in FIG. It expands to the outer diameter d2 of the part 632a. Further, the inner diameter D1 of the communication hole 631a of the cylindrical member 631 shown in FIG. 4 expands to the inner diameter D2 of the communication hole 631a of the cylindrical member 631 shown in FIG.

  At this time, the inner diameter D2 of the communication hole 631a of the cylindrical member 631 shown in FIG. 5 is larger than the outer diameter d2 of the plate portion 632a of the shaft member 632 becomes larger. That is, during the operation of the fuel cell 10 in which high-temperature exhaust fuel flows through the first injection passage 63b, the gap α2 between the cylindrical member 631 and the shaft member 632 causes the cylindrical member when the fuel cell 10 is started up. It becomes larger than the gap α1 between 631 and the shaft member 632.

  As described above, the nozzle 63 according to the present embodiment allows the discharged fuel, which is higher in temperature than the fuel gas raw material, to enter the combustion chamber 623 as compared to when the fuel cell 10 injects the low temperature fuel gas raw material into the combustion chamber 623. During the operation of the fuel cell 10 to be injected, the opening area of the first injection port 63a is enlarged.

For example, the thermal expansion coefficient of the cylindrical member 631 is “19.1 × 10 ⁻⁶ [/ ° C.]”, the thermal expansion coefficient of the shaft member 632 is “7.0 × 10 ⁻⁶ [/ ° C.]”, and the inner diameter at room temperature is When D1 is “42.0 mm” and the outer diameter d1 is “41.95 mm”, the opening area of the first injection port 63a changes as follows.

First, when normal temperature combustible fluid flows through the first injection passage 63b, the opening area of the first injection port 63a becomes 3.3 mm ² , and high temperature (1000 ° C.) combustible fluid flows through the first injection passage 63b. In this case, the opening area of the first injection port 63a is about 37.3 mm ² .

  As described above, the opening area of the first injection port 63a is such that when a high-temperature (1000 ° C.) combustible fluid flows through the first injection passage 63b, a normal temperature combustible fluid flows through the first injection passage 63b. Enlarges 10 times or more.

  Next, the operation of the fuel cell system according to the above configuration will be described. When the fuel cell system receives a signal instructing activation of the fuel cell 10 from a controller (not shown), in order to warm up the components of the system, a low-temperature fuel gas raw material is supplied at a low flow rate via the bypass pipe 6c. It is introduced into the combustion device 6.

  When the low temperature fuel gas raw material is introduced, the combustion device 6 reduces the opening area of the nozzle 63 as shown in FIG. 4, so that a small flow rate of raw material is injected into the combustion chamber 623 at high speed. And burned in the combustion chamber 623. At this time, since the raw material of the fuel gas is injected into the combustion chamber 623 at a high speed, the raw material can be diffused into the combustion chamber 623. As a result, when the fuel cell 10 is started, carbon monoxide (CO) emission due to incomplete combustion in the combustion device 6 can be suppressed.

  After that, the high-temperature combustion gas generated in the combustion device 6 passes through the combustion gas discharge pipe 7 in the order of the fuel reformer 44, the second air preheater 34, the fuel preheater 43, and the first air preheater 33. After being used as a heat source in each device, it is discharged to the outside.

  Subsequently, when the operation of the fuel cell system is started by a control command from a controller (not shown), the air blower 32, the fuel blower 42, the water pump 52, etc. are operated.

  In the air supply pipe 3, after the air pressure-fed by the air blower 32 is heated to a desired temperature by the first air preheater 33, the air is further heated by the second air preheater 34 to be a fuel cell. 10 is supplied.

  On the other hand, in the fuel supply pipe 4, the fuel gas pumped by the fuel blower 42 and the water pumped by the water pump 52 are heated to a desired temperature by the fuel preheater 43 and then fuel reformed. The fuel is reformed into a rich fuel gas by the vessel 44 and supplied to the fuel cell 10.

  When fuel gas and air are supplied, the fuel cell 10 outputs electric energy by the electrochemical reaction shown in the above reaction formulas [F1] to [F4] using hydrogen and carbon monoxide as fuel.

  A large amount of discharged fuel and discharged air discharged from the fuel cell 10 are introduced into the combustion device 6 via the discharge pipes 6a and 6b.

  When the high-temperature exhaust fuel is introduced, the combustion device 6 expands the opening area of the nozzle 63 as shown in FIG. 5, so that a large flow of exhaust fuel is injected into the combustion chamber 623 at a low speed, It is burned in the combustion chamber 623. Since the large amount of discharged fuel is injected into the combustion chamber 623 at a low speed, the pressure loss in the flow path (first injection path 63b) inside the combustion apparatus 6 can be reduced. As a result, the desired exhaust fuel can be introduced into the combustion chamber 623 during the operation of the fuel cell 10.

  After that, the high-temperature combustion gas generated in the combustion device 6 passes through the combustion gas discharge pipe 7 in the order of the fuel reformer 44, the second air preheater 34, the fuel preheater 43, and the first air preheater 33. After being used as a heat source in each device, it is discharged to the outside.

  In the combustion apparatus 6 of the present embodiment described above, the cylindrical member 631 of the nozzle 63 is made of a material having a higher thermal expansion coefficient than the shaft member 632 of the nozzle 63.

  According to this, by utilizing the difference in thermal expansion between the cylindrical member 631 and the shaft member 632 constituting the nozzle 63, the opening area of the nozzle 63 can be used according to the operating conditions of the fuel cell 10 without using a movable valve. Can be changed. As a result, when the fuel cell 10 is started, a low flow rate fuel gas material is injected into the combustion chamber 623 at a high speed, and a large flow rate of discharged fuel is injected into the combustion chamber 623 at a low speed during the operation of the fuel cell 10. It becomes possible.

  Here, since the solid oxide fuel cell requires a long time from a normal temperature state at the time of start-up (for example, 25 ° C.) to a high temperature state (about 800 ° C.) in which power generation is possible, power generation / stop is frequently performed. It is used in an operation mode in which power generation is continued for a long time, not in an operation mode that repeats.

  For this reason, the solid oxide fuel cell has few opportunities to start the fuel cell 10 (for example, about 60 times in 10 years), and it is desirable to suppress the use of a dedicated member used only at the start as much as possible.

  On the other hand, in the present embodiment, as described above, the combustion device 6 can be realized without using a dedicated member that is used only at the time of start-up. Suitable for batteries.

(Second Embodiment)
Next, a second embodiment will be described. In the present embodiment, description of the same or equivalent parts as in the first embodiment will be omitted or simplified.

  Here, when only the gap between the cylindrical member 631 and the shaft member 632 is used as the first injection passage 63b as in the first embodiment, for example, the inner diameter of the communication hole 631a of the cylindrical member 631 changes. Thus, the central axis of the shaft member 632 may be shifted from the central axis of the cylindrical member 631. In this case, there is a possibility that the jetting characteristics of the nozzle 63 change and the combustibility of the combustible fluid becomes unstable.

  Therefore, in the present embodiment, an injection passage for injecting a combustible fluid into the combustion chamber 623 is added to the nozzle 63 separately from the first injection passage 63b. Specifically, as shown in FIGS. 6 and 7, the nozzle 63 of the present embodiment is formed with a second injection passage 631 c having a second injection port 631 b in the tubular member 631. The second injection passage 631c is composed of a plurality of recesses recessed inside the communication hole 631a. The plurality of recesses are evenly formed in the circumferential direction of the communication hole 631a.

  Further, in the present embodiment, the opening area of the second injection port 631b at the time of startup of the fuel cell 10 (the sum of the cross-sectional areas of the respective recesses) is larger than the opening area of the first injection port 63a at the time of startup of the fuel cell 10. It is set to be large. In other words, the first injection port 63a when the opening area of the two injection ports 631b (the sum of the cross-sectional areas of the respective recesses) when the low-temperature fuel gas material flows through the second injection passage 631c is the same condition. It is set to be larger than the opening area.

  Other configurations and operations are the same as those in the first embodiment. According to the combustion apparatus 6 of the present embodiment, the combustible fluid can be stably injected into the combustion chamber 623 through the second injection passage 631c.

  Therefore, according to the combustion apparatus 6 of the present embodiment, it is possible to stabilize the combustibility of the combustible fluid while suppressing the change in the injection characteristics of the nozzle 63. As a result, it is possible to effectively suppress the occurrence of incomplete combustion or the like due to instability of combustibility.

  In particular, in the present embodiment, the opening area of the second injection port 631b when the fuel cell 10 is started is set to be larger than the opening area of the first injection port 63a. According to this, since the combustible fluid is mainly injected from the second injection port 631b when the fuel cell 10 is started, the combustibility of the combustible fluid injected into the combustion chamber 623 can be further stabilized. .

  In the present embodiment, the example in which the second injection passage 631c having the second injection port 631b is formed in the cylindrical member 631 has been described, but the present invention is not limited to this. For example, the second injection passage may be formed on the outer surface of the shaft member 632, or the second injection passage may be formed on both the tubular member 631 and the shaft member 632. Further, the second injection passage 631c is not limited to the concave portion, and may be configured by a through hole.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, In the range described in the claim, it can change suitably. For example, various modifications are possible as follows.

  (1) In each of the above-described embodiments, the example in which the raw material of the fuel gas is introduced into the combustion device 6 when the fuel cell 10 is started is described, but the present invention is not limited to this. For example, a combustible gas other than the fuel gas raw material may be introduced into the combustion device 6 when the fuel cell 10 is started.

  (2) In each of the above-described embodiments, the example in which the discharged fuel is introduced into the combustion device 6 during the operation of the fuel cell 10 has been described, but the present invention is not limited to this. For example, a mixed gas of exhaust fuel and fuel gas may be introduced into the combustion device 6 during operation of the fuel cell 10.

  (3) As in the second embodiment described above, it is desirable that the opening area of the second injection port 631b when starting the fuel cell 10 is larger than the opening area of the first injection port 63a. It is not limited to. For example, the opening area of the second injection port 631b when the fuel cell 10 is activated may be set to be equal to or smaller than the opening area of the first injection port 63a.

  (4) As in the above-described embodiments, it is desirable that a part of the combustion chamber 623 has a tapered shape in consideration of the mixing property of the flammable fluid and the oxidant gas. The chamber 623 may have a cylindrical shape or the like.

  (5) In each of the above-described embodiments, the example in which the shaft member 632 is configured by the dish portion 632a, the trunk portion 632b, and the intermediate portion 632c has been described, but the present invention is not limited to this. That is, the shaft member 632 only needs to have a gap formed between the inner surface of the communication hole 631a of the cylindrical member 631, and the shape thereof is not limited to that described in the above embodiment.

  (6) In each of the above-described embodiments, the example in which the combustion apparatus 6 of the present invention is applied to the solid oxide fuel cell 10 has been described. However, the present invention is not limited to this, and the present invention is applied to other types of fuel cells 10. The combustion device 6 may be applied.

  (7) In each of the above-described embodiments, elements constituting the embodiment are not necessarily indispensable unless specifically indicated as essential and clearly considered essential in principle. Needless to say.

  (8) In each of the above-described embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, the specific number is clearly specified when clearly indicated as essential. It is not limited to the specific number except when limited to.

  (9) In each of the above-described embodiments, when referring to the shape, positional relationship, etc. of the constituent elements, etc., unless specifically stated or limited in principle to a specific shape, positional relationship, etc. It is not limited to shape, positional relationship, and the like.

10 Fuel cell 62 Burner tile (fireproof member)
623 Combustion chamber 63 Nozzle 63a First injection port 63b First injection passage 631 Tubular member 631a Communication hole 632 Shaft member

Claims (5)

The present invention is applied to a fuel cell (10) that outputs electric energy by an electrochemical reaction between a fuel gas and an oxidant gas, and a first combustible fluid is burned when the fuel cell is activated, and the first combustible fluid is operated during operation of the fuel cell. A combustion apparatus for burning the second combustible fluid having a temperature higher than that of the combustible fluid,
A refractory member (62) having a combustion chamber (623) for burning the first combustible fluid and the second combustible fluid formed therein;
A nozzle (63) for injecting the first combustible fluid and the second combustible fluid into the combustion chamber,
The nozzle is
A cylindrical member (631) having a communication hole (631a) communicating with the combustion chamber;
A first injection port (63a) for injecting the first combustible fluid and the second combustible fluid into the combustion chamber is located at least partially inside the communication hole and between the inner surface of the communication hole. A shaft member (632) forming a first injection passage (63b) having,
The said cylindrical member is comprised with the material whose coefficient of thermal expansion is higher than the said shaft member, The combustion apparatus characterized by the above-mentioned.   At least one of the cylindrical member and the shaft member has a second injection passage (631c) having a second injection port (631b) for injecting the first combustible fluid and the second combustible fluid into the combustion chamber. The combustion apparatus according to claim 1, wherein:   The combustion apparatus according to claim 2, wherein an opening area of the second injection port when the fuel cell is started is larger than an opening area of the first injection port when the fuel cell is started. The first combustible fluid is a combustible gas supplied from the outside of the fuel cell,
The combustion apparatus according to any one of claims 1 to 3, wherein the second combustible fluid is an exhausted fuel that is discharged from the fuel cell and contains the fuel gas.   The combustion apparatus according to claim 1, wherein the fuel cell is a solid oxide fuel cell.

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