JP2009224189A - Combustion device of reformer, reformer, and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce NOx concentration and CO concentration by forming a flame having an appropriate shape, in a combustion device of a reformer, a reformer, and a fuel cell system. <P>SOLUTION: In this combustion device of a reformer, the combustion device is provided with: a tubular off-gas nozzle 25c having its axial direction arranged in the combustion pipe 25b along the axial direction of the combustion pipe 25b; a plurality of first jet openings 25c1 opened and formed on a side surface of a tip part of the off-gas nozzle 25c; a partition plate 25b1 fixed between the off-gas nozzle 25c and the combustion pipe 25b at a base end-side position relative to the first jet openings 25c1 of the off-gas nozzle 25c; and a plurality of second jet openings 25b2 formed in the circumference of the off-gas nozzle 25c of the partition plate 25b1 by penetrating in the axial direction of the off-gas nozzle 25c. In diffusive combustion, an anode off-gas or a fuel gas is supplied to the off-gas nozzle 25c and jetted from the first jet openings, and air for combustion is jetted from the second jet openings 25b2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a combustion apparatus for a reformer, a reformer, and a fuel cell system.

  As a type of combustion apparatus of a reformer, one shown in Patent Document 1 is known. As shown in FIG. 1 of Patent Document 1, this combustion apparatus is supplied from a fuel distributor (nozzle) 1 that ejects fuel supplied from a fuel supply apparatus 4 from a fuel injection port 8 and an air supply apparatus 5. Combustion that has an air ejection hole 9 for ejecting the generated air and includes the fuel distributor 1 and the air ejected from the air ejection hole 9 and the fuel ejected from the distributor 1 around the fuel distributor 1 to form a flame And an air ejection member 2 disposed so as to surround the distributor 1 so as to form a space 3.

That is, the inner peripheral wall 2 </ b> B of the air ejection member 2 is inclined to form an inverted frustoconical space. That is, the inner peripheral wall 2B has a cup shape. A plurality of air ejection holes 9 are formed in the inner peripheral wall 2B. The air ejection holes 9 are formed on a plurality of rows (three rows) concentric circles. The cup-shaped space that is the inner hole of the air ejection member 2 becomes a combustion space 3 in which a flame is formed and combustion is performed. In the lower part of the combustion space 3, a tubular fuel distributor 3 whose tip is closed is fitted. The fuel distributor 3 is disposed so that a tip end portion provided with a plurality of fuel injection holes 8 in the circumferential direction protrudes from a central portion of the combustion space 3 having a circular cross section.
JP 2004-156895 A

In the combustion apparatus described in Patent Document 1 described above, the fuel injection hole 8 and the air injection hole 9 closest to the fuel injection hole 8 are opposed to each other because the fuel and air injected from the respective holes 8 and 9 are opposed to each other. Difficult to spread and difficult to form stably. Further, since the air ejected from the plurality of rows of air ejection holes 9 located on the outer periphery of the innermost air ejection hole 9 is ejected toward the center of the combustion space 3 (the central axis of the fuel distributor 3), However, it is difficult for the flame to spread and to be formed stably. From these, which may result an increase of the NO _X concentration, an increase in the CO concentration. Moreover, the combustion load which can ensure the mixing property of fuel and combustion air is low, and it is difficult to reduce the CO concentration with respect to the combustion load in a wide generated power range (for example, 300 W to 1000 W).

The present invention has been made to solve the above problem, a combustion device of the reformer, the reformer and the fuel cell system, to form a flame suitable shape, reduction of the NO _X concentration, CO The purpose is to reduce the concentration.

  In order to solve the above-described problem, a structural feature of the reformer combustion apparatus according to claim 1 is that the reforming fuel is reformed to generate a fuel gas containing hydrogen to produce a fuel cell. In a combustion apparatus that is provided in a reformer having a reforming section that supplies to a fuel electrode and heats the reforming section, the combustion apparatus includes a cylindrical cylinder and an axial direction of the cylinder inside the cylinder. A cylindrical nozzle provided with an axial direction, a plurality of first injection ports provided on the side surface of the tip of the nozzle, and a position between the nozzle and the cylinder at a position proximal to the first injection port of the nozzle And a plurality of second injection ports provided around the nozzle of the plate member in the axial direction of the nozzle, from the anode off-gas from the fuel electrode or the reforming unit When the diffusive combustion is performed by diffusing and burning the fuel gas with the oxidant gas for combustion, the anode from the fuel electrode Fugas or fuel gas from the reforming section is supplied to the nozzle, and oxidant gas for combustion is supplied so as to be ejected from the second outlet, and the fuel for combustion and the oxidant gas for combustion are premixed for combustion. At the time of premixed combustion in which fuel is premixed, combustion fuel and combustion oxidant gas are premixed and supplied so as to be ejected from the second outlet.

  A structural feature of the invention according to claim 2 is that, in claim 1, the cylindrical body is provided so as to cover the tip of the nozzle.

  A structural feature of the invention of the reforming apparatus according to claim 3 is that the reforming section is heated by the combustion apparatus according to claim 1 or claim 2.

  A feature of the invention of the fuel cell system according to claim 4 is that fuel gas generated by the reformer according to claim 3 is supplied to the fuel electrode.

In the invention of the combustion apparatus of the reformer according to claim 1 configured as described above, the anode off-gas or the fuel gas is removed from the nozzle from the first injection port provided to be opened at the side surface of the tip of the nozzle. Is ejected toward the outside (outside). Further, a plurality of second injection ports provided around the nozzle in the axial direction of the nozzle of a plate-like member fixed between the nozzle and the cylindrical body at a position proximal to the first injection port of the nozzle From the first injection port when the anode off-gas or fuel gas is ejected (diffusion combustion), or when the anode off-gas and fuel gas are not ejected from the first injection port (premixing) During combustion), the mixed gas is ejected toward the protruding end of the nozzle. In this way, the tip of the nozzle provided with the first outlet is protruded from the plate-like member provided with the second outlet, and the outer side of the nozzle from the first outlet (at the time of diffusion combustion) The anode off-gas or fuel gas ejected toward the outside) flows toward the nozzle tip protrusion side by the flow of the combustion oxidant gas sprayed from the second outlet toward the nozzle tip protrusion side, A flame that spreads outward (outside) is directed in a direction along the axial direction of the nozzle. Thus, without suppressing unnecessarily spread of flame, and it is possible to form a flame squeezed some extent, to form a flame suitable shape, reduction of the NO _X concentration, reduction in CO concentration Can be achieved. Further, since the mixing property is also ensured, it is possible to secure a low CO concentration in a wide turndown (for a combustion load in a wide generated power range).

  In the invention according to claim 2 configured as described above, in the invention according to claim 1, since the cylinder is provided so as to cover the tip of the nozzle, premixed combustion and diffusion combustion are performed in the cylinder ( In other words, it is possible to more appropriately form a flame with a certain degree of spread without suppressing the spread of the flame more than necessary, and more reliably form a flame with an appropriate shape. can do.

In the invention of a reformer according to claim 3 as constructed above, since heating the reforming section by the combustion device according to claim 1 or claim 2, reduction of the NO _X concentration, reduction in CO concentration Thus, it is possible to provide a reformer capable of ensuring a low CO concentration in a wide turndown.

In the invention of a fuel cell system according to Claim 4 as constructed above, since the fuel gas generated by the reforming apparatus according to claim 3 is supplied to the fuel electrode, reduction of the NO _X concentration, CO concentration It is possible to provide a fuel cell system that can reduce the CO2 and secure a low CO concentration in a wide turndown.

  Hereinafter, an embodiment of a fuel cell system to which a combustion apparatus of a reformer according to the present invention is applied will be described. FIG. 1 is a schematic diagram showing an outline of this fuel cell system. The fuel cell system includes a fuel cell 10 and a reformer 20 that generates a reformed gas (fuel gas) containing hydrogen gas necessary for the fuel cell 10.

  The fuel cell 10 includes a fuel electrode 11, an air electrode 12 that is an oxidant electrode, and an electrolyte 13 interposed between the electrodes 11 and 12, and supplies the reformed gas supplied to the fuel electrode 11 and the air electrode 12. Electric power is generated using air (cathode air), which is the oxidant gas. Note that air-enriched gas may be supplied instead of air.

  The reformer 20 steam-reforms the reforming fuel and supplies a hydrogen-rich reformed gas to the fuel cell 10. , A CO shift unit) 23, a carbon monoxide selective oxidation reaction unit (hereinafter referred to as a CO selective oxidation unit) 24, a combustion unit (combustion device) 25, and an evaporation unit 26. Examples of the reforming fuel include natural gas, gas fuel for reforming such as LPG, and liquid fuel for reforming such as kerosene, gasoline, and methanol. In the present embodiment, description will be made on natural gas.

  The reforming unit 21 generates and derives a reformed gas from a mixed gas that is a reforming raw material in which reforming water is mixed with the reforming fuel. The reforming portion 21 is formed in a bottomed cylindrical shape, and includes an annular folded channel 21a extending along the axis in the annular cylindrical portion.

  The return channel 21 a of the reforming unit 21 is filled with a catalyst 21 b (for example, a Ru or Ni-based catalyst) and introduced from the reforming fuel introduced from the cooling unit 22 and the steam supply pipe 51. The gas mixture with the steam reacts and is reformed by the catalyst 21b to generate hydrogen gas and carbon monoxide gas (so-called steam reforming reaction). At the same time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide generated in the steam reforming reaction reacts with steam to transform into hydrogen gas and carbon dioxide. These generated gases (so-called reformed gas) are led to a cooling unit (heat exchange unit) 22. The steam reforming reaction is an endothermic reaction, and the carbon monoxide shift reaction is an exothermic reaction.

  The cooling unit 22 is a heat exchanger (heat exchange unit) in which heat exchange is performed between the reformed gas derived from the reforming unit 21 and a mixed gas of reforming fuel and reformed water (steam). The temperature of the reformed gas having a high temperature is lowered by the mixed gas having a low temperature and led to the CO shift unit 23, and the temperature of the mixed gas is raised by the reformed gas and led to the reforming unit 21. Yes.

  Specifically, a reforming fuel supply pipe 41 connected to a fuel supply source (not shown) (for example, a city gas pipe) is connected to the cooling unit 22. The reforming fuel supply pipe 41 is provided with a fuel pump 42, a desulfurizer 46, and a reforming fuel valve 43 in order from the upstream. The reforming fuel valve 43 opens and closes the reforming fuel supply pipe 41. The fuel pump 42 is reforming fuel supply means for supplying reforming fuel and adjusting the supply amount. The desulfurizer 46 reduces the sulfur content (for example, sulfur compound) in the fuel. Of the fuel supplied from the fuel supply source, the fuel supplied to the reforming unit 21 and reformed is called reforming fuel, and the fuel supplied to the combustion unit 25 and combusted is called combustion fuel.

  A combustion fuel supply pipe 44 connected to a combustion air supply pipe 64 connected to the combustion section 25 is connected between the desulfurizer 46 and the reforming fuel valve 43 of the reforming fuel supply pipe 41. Has been. A combustion fuel valve 45 is provided in the combustion fuel supply pipe 44. The combustion fuel valve 45 opens and closes the combustion fuel supply pipe 44. When the fuel pump 42 is driven and the reforming fuel valve 43 is closed and the combustion fuel valve 45 is opened, the combustion fuel is supplied to the combustion unit 25, and the fuel pump 42 is driven and the reforming fuel. When the valve 43 is opened and the combustion fuel valve 45 is closed, the reforming fuel is supplied to the reforming unit 21.

  Further, a steam supply pipe 51 connected to the evaporation section 26 is connected between the reforming fuel valve 43 and the cooling section 22 of the reforming fuel supply pipe 41. The steam supplied from the evaporation unit 26 is mixed with the reforming fuel, and the mixed gas is supplied to the reforming unit 21 through the cooling unit 22.

  The CO shift unit 23 is a unit that reduces carbon monoxide in the reformed gas supplied from the reforming unit 21 through the cooling unit 22, that is, a carbon monoxide reducing unit. The CO shift unit 23 includes a folded channel 23a extending along the vertical direction. The return channel 23a is filled with a catalyst 23b (for example, a Cu—Zn-based catalyst). In the CO shift unit 23, a so-called carbon monoxide shift reaction in which carbon monoxide and water vapor contained in the reformed gas introduced from the cooling unit 22 react with the catalyst 23b to be converted into hydrogen gas and carbon dioxide gas. Has occurred. This carbon monoxide shift reaction is an exothermic reaction.

  The CO selective oxidation unit 24 further reduces the carbon monoxide in the reformed gas supplied from the CO shift unit 23 and supplies it to the fuel cell 10, that is, a carbon monoxide reduction unit. The CO selective oxidation unit 24 is formed in a cylindrical shape, and is provided so as to cover the outer peripheral wall of the evaporation unit 26. The CO selective oxidation unit 24 is filled with a catalyst 24a (for example, a Ru or Pt catalyst).

  A connecting pipe 89 connected to the CO shift section 23 and a reformed gas supply pipe 71 connected to the fuel electrode 11 of the fuel cell 10 are connected to the lower and upper side walls of the CO selective oxidation section 24, respectively. ing. An oxidation air supply pipe 61 is connected to the connection pipe 89. As a result, the reformed gas from the CO shift unit 23 and the oxidizing air from the atmosphere are introduced into the CO selective oxidation unit 24. The oxidizing air supply pipe 61 is provided with an oxidizing air pump 62 and an oxidizing air valve 63 in order from the upstream. The oxidizing air pump 62 supplies oxidizing air and adjusts the supply amount. The oxidation air valve 63 opens and closes the oxidation air supply pipe 61.

  Therefore, carbon monoxide in the reformed gas introduced into the CO selective oxidation unit 24 reacts (oxidizes) with oxygen in the oxidizing air to become carbon dioxide. This reaction is an exothermic reaction and is promoted by the catalyst 24a. Thereby, the reformed gas is derived by further reducing the carbon monoxide concentration (10 ppm or less) by the oxidation reaction, and is supplied to the fuel electrode 11 of the fuel cell 10.

  A CO selective oxidation unit 24 is connected to the inlet of the fuel electrode 11 of the fuel cell 10 via a reformed gas supply pipe 71, and the combustion unit 25 is connected to the outlet of the fuel electrode 11 via an offgas supply pipe 72. Is connected. The bypass pipe 73 bypasses the fuel cell 10 and directly connects the reformed gas supply pipe 71 and the offgas supply pipe 72. The reformed gas supply pipe 71 is provided with a first reformed gas valve 74 between the branch point of the bypass pipe 73 and the fuel cell 10. The off gas supply pipe 72 is provided with an off gas valve 75 between the junction with the bypass pipe 73 and the fuel cell 10. A second reformed gas valve 76 is provided in the bypass pipe 73.

  During the start-up operation, the first reformed gas valve 74 and the offgas valve 75 are closed and the second reformed gas valve 76 is opened in order to avoid supplying reformed gas having a high carbon monoxide concentration from the reformer 20 to the fuel cell 10. During the steady operation (power generation operation), the first reformed gas valve 74 and the offgas valve 75 are opened and the second reformed gas valve 76 is closed in order to supply the reformed gas from the reformer 20 to the fuel cell 10. .

  A cathode air supply pipe 67 is connected to the inlet of the air electrode 12 of the fuel cell 10, and an exhaust pipe 82 is connected to the outlet of the air electrode 12. Air is supplied to the air electrode 12, and off-gas is exhausted. The cathode air supply pipe 67 is provided with a cathode air pump 68 and a cathode air valve 69 in order from the upstream. The cathode air pump 68 supplies cathode air and adjusts the supply amount. The cathode air valve 69 opens and closes the cathode air supply pipe 67.

  The combustion part 25 generates combustion gas for heating the reforming part 21 and supplying heat necessary for the steam reforming reaction. The lower end part is inserted into the inner peripheral wall of the reforming part 21. It is arranged with a space. The combustion section 25 is supplied with anode off-gas from the fuel electrode 11 or fuel gas from the reforming section 21 and supplied with combustion oxidant gas, and diffuses and burns the anode off-gas with the combustion oxidant gas, or supplies fuel. This is a combustion apparatus in which a combustion fuel and a combustion oxidant gas from a source are premixed and supplied, burn the premixed gas, and heat the reforming section 21 with any of the combustion gases.

  As shown in FIG. 2, the combustion unit 25 includes a base 25a, a cylindrical combustion cylinder (cylinder) 25b provided on the base 25a and communicating with the base 25a, an off-gas nozzle 25c, a temperature sensor 25e, It has. The combustion unit 25 is ignited by an ignition electrode (not shown) according to a command from the control device.

  The base portion 25a includes a base plate 25a1 and a base casing 25a2 that covers and is fixed to the base plate 25a1. An off gas supply pipe 72 is connected to the base plate 25a1, and a base end of an off gas nozzle 25c is connected to an inner wall surface facing the space (internal space) 25a4 of the base plate 25a1. The off gas supply pipe 72 and the off gas nozzle 25c are communicated with each other through a connection path 25a3 formed in the base plate 25a1, and either the anode off gas or the reformed gas is introduced (supplied) to the off gas nozzle 25c. A combustion air supply pipe 64 is connected to the base casing 25a2, and combustion air or a premixed gas in which combustion air and combustion fuel are premixed is formed in the base 25a by the base plate 25a1 and the base casing 25a2. Introduced into the space 25a4. The port 64a through which either combustion air or premixed gas is introduced into the space 25a4 is the first introduction port.

  The upper end (one end) of the combustion cylinder 25b is connected to the base casing 25a2 of the base portion 25a, and the lower side (the other end) is opened. A disc-shaped partition plate 25b1 is provided in the middle of the combustion cylinder 25b in the longitudinal direction (for example, the lower end side from the middle), and partitions the combustion cylinder 25b in the longitudinal direction.

  The off-gas nozzle 25c is a nozzle in which an axial direction is provided inside the combustion cylinder 25b along the axial direction of the combustion cylinder 25b. The off-gas nozzle 25c extends in the space 25a4 and the combustion cylinder 25b toward the partition plate 25b1, passes through the center of the partition plate 25b1, and extends to the combustion space 25d. The tip portion of the off-gas nozzle 25c is closed, and a first injection port 25c1 is provided in a side surface portion (tip portion) slightly away from the tip. A plurality of the first injection ports 25c1 are provided so as to open to the side surface of the tip of the off-gas nozzle 25c. In the present embodiment, a plurality of (four in the present embodiment) first injection ports 25c1 are provided in the radial direction of the off-gas nozzle 25c. The first injection port 25c1 has a substantially circular cross section. The anode off gas or the reformed gas supplied from the base end side is ejected radially outward from the plurality of first injection ports 25c1 and introduced into the combustion space 25d. The off gas nozzle 25c is used not only for anode off gas but also for reformed gas bypassing the fuel cell 10.

  The combustion space 25d is a portion provided for burning the combustible gas, and is a space on the side where the tip of the off-gas nozzle 25c protrudes from the partition plate 25b1 in the combustion cylinder 25b. A portion of the combustion cylinder 25b that is at the tip of the partition plate 25b1 is a hood 25b3. The hood 25b3 is provided so as to cover the tip portion protruding from the partition plate 25b1 of the off-gas nozzle 25c.

  The partition plate 25b1 is a plate-like member fixed between the offgas nozzle 25c and the combustion cylinder 25b at a base end side position from the first injection port 25c1 of the offgas nozzle 25c. The partition plate 25b1 is fixed so as to be orthogonal to the off-gas nozzle 25c. The partition plate 25b1 has a flat plate shape in the present embodiment, but may not have a flat plate shape.

  A plurality of second injection ports 25b2 (16 in the embodiment) are provided around the off-gas nozzle 25c of the partition plate 25b1. The second injection port 25b2 is provided through the partition plate 25b1 in the axial direction. In the present embodiment, the second injection port 25b2 is provided to open in a direction parallel to the axial direction of the off-gas nozzle 25c. The second injection port 25b2 only needs to penetrate in the axial direction, and may not be parallel to the axial direction but may be inclined. The second injection port 25b2 has a substantially circular cross section.

  The base 25a, the combustion cylinder 25b, and the partition plate 25b1 constitute a housing 25g. Further, an internal space 25h (a space partitioned from the base 25a, the combustion cylinder 25b, and the partition plate 25b1) is formed in the housing 25g. The internal space 25h is formed by a space 25a4 and a portion on the base 25a side partitioned by the partition plate 25b1 in the space between the combustion cylinder 25b and the offgas nozzle 25c.

  In the case of diffusion combustion in which anode off gas or fuel gas is diffused and burned with combustion air, anode off gas or fuel gas is supplied to the off gas nozzle 25c, and combustion air is supplied so as to be ejected from the second injection port 25b2. . That is, the anode off-gas or fuel gas supplied to the off-gas nozzle 25c is ejected from the first injection port 25c1 toward the radially outer side of the off-gas nozzle 25c and is introduced into the combustion space 25d. Combustion air introduced into the space 25a4 in the base portion 25a is ejected from the second ejection port 25b2 toward the tip protruding side of the off-gas nozzle 25c, and is introduced into the combustion space 25d. In this case, the anode offgas or fuel gas ejected from the first injection port 25c1 toward the radially outer side of the offgas nozzle 25c is ejected from the second injection port 25b2 toward the tip protruding side of the offgas nozzle 25c. The flow of air makes the flow toward the tip protruding side of the off-gas nozzle 25c, and the flame 25f trying to spread outward is directed in the direction along the axial direction of the off-gas nozzle 25c.

  On the other hand, in the case of the premixed combustion in which the combustion fuel and the combustion air are premixed and the combustion fuel is premixed and combusted, the combustion fuel and the combustion air are premixed from the second injection port 25b2. Supplied to spout. That is, the premixed gas introduced into the space 25a4 in the base portion 25a is ejected from the second ejection port 25b2 toward the tip protruding side of the off-gas nozzle 25c and is introduced into the combustion space 25d. The premixed gas is supplied through the combustion air supply pipe 64.

  The temperature sensor 25e detects the radiation temperature of the flame 25f generated in the combustion space 25d of the combustion unit 25 and transmits the detection result to the control device (for example, a radiation thermometer). The temperature sensor 25e is, for example, a sheath thermocouple, and is inserted into the combustion space 25d through the base plate 25a1 of the base portion 25a and through the partition plate 25b1. The tip portion (slightly behind the tip 25e1) is a temperature measurement unit. The tip 25e1 of the temperature sensor 25e is provided so as to be closer to the partition plate 25b1 than the end 25c2 of the first injection port 25c1 on the partition plate 25b1 side, but is not limited thereto. Any position where the temperature measuring unit of the temperature sensor 25e can measure the radiation temperature of the flame 25f may be used. Specifically, it suffices if it is outside the flame surface 25f1 of the flame 25f inside the combustion space 25d. Here, the flame surface refers to a boundary surface between a portion where a combustion reaction (oxidation reaction) of combustible gas (for example, anode off-gas, premixed gas (including combustion fuel)) occurs and other portions. In the present embodiment, a thermocouple is used as the temperature sensor 25e, but a thermistor may be used.

  The combustion air supply pipe 64 is provided with a combustion air pump (combustion oxidant gas supply means) 65 and a combustion air valve 66, as shown in FIG. The combustion air pump 65 sucks combustion air from the atmosphere and discharges it to the combustion unit 25, and adjusts the amount of combustion air supplied to the combustion unit 25 in accordance with a command from the control device. The combustion air valve 66 opens and closes the combustion air supply pipe 64 in accordance with a command from the control device.

  The combustion air valve 66 is opened and combustion is performed from the time when the system is started (starting of the fuel cell system (reforming device 20) is started) until the supply of the reforming fuel to the reforming unit 21 is started. As the air pump 65 is driven, the reforming fuel valve 43, the first reformed gas valve 74, and the offgas valve 75 are closed, the combustion fuel valve 45 is opened, and the fuel pump 42 is driven. The combustion fuel passes through the combustion fuel supply pipe 44 without passing through the reforming section 21 and is mixed with the combustion air in the combustion air supply pipe 64 and mixed, and the premixed gas passes through the combustion air supply pipe 64. It is supplied to the combustion part 25 through. Supply of the reforming fuel to the reforming unit 21 is started after steam is generated in the evaporation unit 26 and the reforming unit 21 reaches a predetermined temperature or higher.

  In addition, the reforming fuel valve 43 and the second reformed gas valve 76 are opened from the start of supply of the reforming fuel to the reforming unit 21 to the start of steady operation (power generation), and the combustion fuel valve 45 is opened. Is closed and the fuel pump 42 is driven. The first reformed gas valve 74 and the offgas valve 75 remain closed. Thus, in order to avoid supplying reformed gas having a high carbon monoxide concentration from the CO selective oxidation unit 24 to the fuel cell 10, the reformed gas from the CO selective oxidation unit 24 is supplied to the fuel cell 10 in the combustion unit 25. Supplied directly without going through. Combustion air is supplied in the same manner as described above. In other words, the reforming gas is supplied to the combustion unit 25 through the off-gas supply pipe 72 and combustion air is supplied through the combustion air supply pipe 64.

  During steady operation (power generation), the reforming fuel valve 43, the first reformed gas valve 74, and the offgas valve 75 are opened, the combustion fuel valve 45 and the second reformed gas valve 76 are closed, and the fuel pump. 42 is driven. As a result, the combustion portion 25 contains the anode off-gas from the fuel electrode 11 of the fuel cell 10 (hydrogen that has been supplied to the fuel electrode 11 of the fuel cell 10 and discharged without being consumed, or unreformed reforming fuel). Reformed gas) is supplied. Combustion air is supplied in the same manner as described above. That is, anode offgas is supplied to the combustion unit 25 through the offgas supply pipe 72 and combustion air is supplied through the combustion air supply pipe 64. At this time, the combustion unit 25 does not recharge the combustion by separately adding a combustible gas such as a combustion fuel. This is a so-called reboundless system.

  As described above, in the combustion unit 25, the combustion fuel, reformed gas, or anode off gas (these are combustible gases) supplied to the combustion unit 25 are combusted by the combustion air supplied to the combustion unit 25. Hot combustion gas is generated. This combustion gas is formed between the reforming section 21 and the heat insulating section 28 and between the heat insulating section 28 and the evaporation section 26 and disposed so as to heat the reforming section 21 and the evaporation section 26. It flows through the flow path 27, passes through the exhaust pipe 81, and is discharged to the outside as combustion exhaust gas. The combustion gas heats the reforming catalyst 21a of the reforming unit 21 so as to be in the activation temperature range, and heats the evaporation unit 22 to generate water vapor.

  The evaporation unit 26 evaporates the reformed water to generate water vapor, and supplies the water vapor to the reforming unit 21 via the cooling unit 22. The evaporator 26 is formed in a cylindrical shape so as to cover and contact the outer peripheral wall of the combustion gas passage 27.

  A water supply pipe 52 connected to a reforming water tank (not shown) is connected to a lower portion (for example, a lower portion of the side wall surface and a bottom surface) of the evaporation section 26. A water vapor supply pipe 51 is connected to the upper part (for example, the upper part of the side wall surface) of the evaporation unit 26. The reformed water introduced from the reformed water tank is heated by the heat from the combustion gas and the heat from the CO selective oxidation unit 24 in the course of flowing through the evaporation unit 26 to become water vapor and the water vapor supply pipe 51. And it leads to the reforming part 21 through the cooling part 22. The water supply pipe 52 is provided with a reforming water pump 53 and a reforming water valve 54 in order from the upstream. The reforming water pump 53 supplies reforming water to the evaporation unit 26 and adjusts the reforming water supply amount. The reforming water valve 54 opens and closes the water supply pipe 52.

As is apparent from the above description, in this embodiment, the first injection port 25c1 that opens (opens in the radial direction) on the side surface of the tip of the off-gas nozzle (nozzle) 25c is connected to the anode. Off-gas or fuel gas is ejected outward (radially outward) from the off-gas nozzle 25c. Further, a partition plate (plate member) 25b1 fixed between the offgas nozzle 25c and the combustion cylinder (cylinder) 25b at a position proximal to the first injection port 25c1 of the offgas nozzle 25c, around the offgas nozzle 25c. Combustion air (when diffusion combustion) is performed from a plurality of second injection ports 25b2 provided penetrating in the axial direction of the off-gas nozzle 25c when the anode off-gas or fuel gas is injected from the first injection port 25c1 (diffusion combustion). When the anode oxidant gas and the fuel gas are not ejected from the first injection port 25c1 (during premixed combustion), the mixed gas is ejected toward the tip protruding side of the offgas nozzle 25c. Thus, the tip of the off-gas nozzle 25c provided with the first injection port 25c1 protrudes from the partition plate 25b1 provided with the second injection port 25b2, and from the first injection port 25c1 during diffusion combustion. The anode off-gas or fuel gas ejected toward the outside (radially outer side) of the off-gas nozzle 25c is caused by the flow of combustion air ejected from the second injection port 25b2 toward the tip protruding side of the off-gas nozzle 25c. The flow is directed toward the tip protruding side of the off gas nozzle 25c, and the flame that spreads outward is directed in a direction along the axial direction of the off gas nozzle 25c. Thus, without suppressing unnecessarily spread of flame, and it is possible to form a flame squeezed some extent, to form a flame suitable shape, reduction of the NO _X concentration, reduction in CO concentration Can be achieved. Further, since the mixing property is also ensured, it is possible to secure a low CO concentration in a wide turndown (for a combustion load in a wide generated power range).

  Further, since the combustion cylinder (cylinder) 25b is provided so as to cover the tip of the off-gas nozzle 25c, premixed combustion and diffusion combustion are performed in the hood 25b3 (that is, the combustion space 25d), so that the flame It is possible to more appropriately form a flame with a certain degree of spread without suppressing the spread more than necessary, and it is possible to more reliably form an appropriately shaped flame.

Further, since heating the reforming section 21 by the combustion device 25, to provide a NO _X concentration reduction of reformer which is capable also ensuring low CO concentration in a wide turndown with reduced CO concentration 20 Can do.

Further, since the fuel gas produced by the reformer 20 is supplied to the fuel electrode 11, NO _X concentration reduction of a low CO concentration fuel cell ensuring the possible and of a wide turndown with reduced CO concentration A system can be provided.

1 is a schematic diagram showing an outline of an embodiment of a fuel cell system to which a combustion apparatus of a reformer according to the present invention is applied. It is sectional drawing which shows the combustion part shown in FIG. FIG. 3 is a cross-sectional view taken along line 3-3 shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Fuel electrode, 12 ... Air electrode, 20 ... Reformer, 21 ... Reformer, 22 ... Cooling part (heat exchange part), 23 ... Carbon monoxide shift reaction part (CO shift part) 24 ... Carbon monoxide selective oxidation reaction part (CO selective oxidation part), 25 ... Combustion part (combustion device), 25a ... Base part, 25b ... Combustion cylinder, 25b1 ... Partition plate (planar plate member), 25b2 ... Second Jet port, 25c ... off gas nozzle, 25c1 ... first jet port, 25e ... temperature sensor, 25g ... housing, 25h ... internal space, 26 ... evaporating part, 27 ... combustion gas flow path, 28 ... heat insulating part, 41 ... fuel Supply pipe, 42 ... Fuel pump, 43 ... Reforming fuel valve, 44 ... Combustion fuel supply pipe, 45 ... Combustion fuel valve, 46 ... Desulfurizer, 51 ... Steam supply pipe, 52 ... Feed water pipe, 53 ... Kai Quality water pump, 54 ... reformed water valve, 61 ... oxidation air Supply pipe, 62 ... oxidation air pump, 63 ... oxidation air valve, 64 ... combustion air supply pipe, 65 ... combustion air pump, 66 ... combustion air valve, 67 ... cathode air supply pipe, 68 ... cathode Air pump, 69 ... cathode air valve, 71 ... reformed gas supply pipe, 72 ... off gas supply pipe, 73 ... bypass pipe, 74 ... first reformed gas valve, 75 ... off gas valve, 76 ... second reformed gas valve 81, 82 ... exhaust pipe, 89 ... connection pipe.

Claims (4)

In a combustion apparatus that is provided in a reformer having a reformer that generates a fuel gas containing hydrogen by reforming a reforming fuel and supplies the fuel gas to a fuel electrode of a fuel cell and heats the reformer,
The combustion device comprises:
A cylindrical cylinder, and a cylindrical nozzle provided with an axial direction along the axial direction of the cylindrical body inside the cylindrical body;
A plurality of first injection ports provided to be open on the side surface of the tip of the nozzle;
A plate-like member fixed between the nozzle and the cylindrical body at a position proximal to the first injection port of the nozzle;
A plurality of second injection ports provided in the axial direction of the nozzle around the nozzle of the plate-like member,
At the time of diffusion combustion in which the anode off gas from the fuel electrode or the fuel gas from the reforming portion is diffusely burned with a combustion oxidant gas, the anode off gas from the fuel electrode or the fuel gas from the reforming portion is supplied to the nozzle. Is supplied, and is supplied so that the combustion oxidant gas is ejected from the second ejection port,
During the premix combustion in which the combustion fuel and the combustion oxidant gas are premixed and the combustion fuel is premixed and combusted, the combustion fuel and the combustion oxidant gas are premixed and the second outlet A combustion apparatus for a reforming apparatus, wherein the combustion apparatus is supplied so as to be ejected from a combustion chamber.   The reformer combustion apparatus according to claim 1, wherein the cylindrical body is provided so as to cover a tip portion of the nozzle.   A reformer that heats the reformer using the combustion apparatus according to claim 1.   The fuel cell system characterized by supplying the fuel gas produced | generated by the reformer of Claim 3 to the said fuel electrode.

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