JP2001201019A - Combustion device for fuel cell system and hydrogen generating device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion device having a simplified structure of low cost and a hydrogen manufacturing device of a fuel cell system, in which both off-gas and fuel gas of high calories are ignited at common flame holes as the combustion device for the hydrogen manufacturing apparatus for a fuel cell attaining hydrogen used in the fuel cell system under a reaction between raw material gas and water vapor. SOLUTION: There are provided a combustion device and a hydrogen manufacturing device having the combustion device in which high calorie gas and off-gas are supplied to flame holes of a combustion device under application of a double-pipe, a fuel gas discharging part is formed at its central part, a slant surface of the flame hole plate expanding in a cone-shape, the flame holes for the high calorie gas are made common to that for off-gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device for heating a reforming catalyst and a hydrogen hydrogen production device used for a hydrogen production device of a fuel cell system.

[0002]

2. Description of the Related Art A fuel cell system is a system for converting the chemical energy of hydrogen into electric energy. Naturally, it is relatively easy and inexpensive to obtain natural gas and hydrocarbon gas such as naphtha. A raw material gas for reforming alcohols such as methanol (hereinafter simply referred to as a raw material gas) and steam are mixed and reacted in a reformer to generate a reformed gas containing hydrogen as a main component. The gas is supplied to the electrode (fuel electrode) of the fuel cell body to generate power.

[0003] In this reformer, since the reaction of reforming a raw material gas or the like and steam with a catalyst in the presence of a catalyst to extract hydrogen is an endothermic reaction, a combustion device is provided in the reformer, and the reaction is carried out by the combustion device. The vessel needs to be heated.

[0004] A combustion device for heating a catalyst of a reformer generally uses methanol or natural fuel as fuel in the initial stage of operation after the fuel cell starts operating until the catalyst layer of the reformer enters a reaction start state. Although hydrocarbon fuels such as gas are used,
After the power generation in the fuel cell system is started, the unreacted gas (battery off-gas fuel) containing a large amount of hydrogen discharged from the fuel cell system can also be used as fuel for the combustion device in the fuel cell system. Like that.

[0005] As such a combustion apparatus, for example, Japanese Patent Application Laid-Open Nos. 5-303974 and 8-152114 propose the following structures.

In Japanese Patent Application Laid-Open No. 5-303974, a high calorie gas passage, a first oxidant gas passage, a low calorie gas passage, and a second oxidant gas passage are provided in order from the center of the combustion device toward the outside in the radial direction. When a high calorie gas of hydrocarbon fuel gas is used, it is passed through a high calorie gas passage, and when a low calorie gas such as a battery off-gas fuel is used, it is passed through a low calorie gas passage. The combustor is a horizontal structure that burns high-calorie fuel and low-calorie fuel.

In Japanese Patent Application Laid-Open No. Hei 8-152114, a low calorie gas fuel supply pipe is directly connected to a low calorie gas fuel supply section which communicates with a low calorie gas flame hole. On the other hand, the high-calorie gas fuel supply section connected to the high-calorie gas flame port has a structure in which high-calorie gas supplied from a high-calorie gas fuel supply pipe and combustion air are mixed and burned.

[0008]

By the way, the above-mentioned cell off-gas containing a large amount of hydrogen has a calorific value per unit volume of several minutes as compared with natural gas which is a hydrocarbon fuel used as a fuel for initial heating. Therefore, even when a low calorie gas is used as a fuel, it is not calorically possible to use a high calorie fuel jet.

[0009] Further, since the burning rate of the above-mentioned battery off-gas containing a large amount of hydrogen is several times faster than the burning rate of natural gas, flashback may occur when the balance between the air volume and the gas volume changes. However, there is a risk of damaging the combustion device body.

For this reason, in this type of conventional combustion device,
A high calorie flame hole for hydrocarbon fuel and a low calorie flame hole for battery off-gas are separately formed, and a flame forming portion (flame hole) by low calorie gas and a flame forming portion by high calorie gas (Flame holes) were formed in different places. However, when two flame forming portions are provided in the same combustor, the structure is inevitably complicated, and the manufacturing cost is increased. In addition, since flame formation portions of fuel gas having different properties are formed at two locations, there is a problem that it is difficult to perform flame detection with one sensor.

According to the present invention, the structure is simple, flame detection is easy,
It is another object of the present invention to provide a fuel cell hydrogen production apparatus capable of performing stable combustion and a combustion apparatus therefor.

[0012]

According to a first aspect of the present invention, there is provided a combustion apparatus for a fuel cell system, which burns a high calorie hydrocarbon gas and a low calorie gas obtained from off-gas of a fuel cell. The combustion apparatus includes a gas mixing section of high-calorie gas and low-calorie gas around the discharge section with the low-calorie gas or high-calorie gas discharge section at the center, and the discharge section and the gas. It is characterized by having a flame hole part spreading in a mortar shape with the mixing part as the center.

According to a second aspect of the present invention, a high-calorie gas supply path for supplying high-calorie gas to the flame hole and a low-calorie gas supply path for supplying low-calorie gas are provided in a double pipe structure. A combustion device for a fuel cell system, comprising:

According to a third aspect of the present invention, there is provided the first or second aspect.
A combustion device for a fuel cell system, characterized in that the flame hole section described in (1) has a structure in which an air ejection hole is provided in a mortar-shaped flame hole plate.

[0015] The invention of claim 4 is the invention of claims 1 to 3
The flame hole according to any of the above, has a gas diffusion plate having the same shape as the cross section of the flame hole at the downstream end of the inner pipe of the gas supply path having a double pipe structure. A combustion device for a fuel cell system.

Further, the invention of claim 5 provides the invention of claim 3
Or the mortar-shaped flame hole plate of the flame hole part according to 4 has a large number of pores or slit-shaped air ejection holes on its inclined surface radially outward with respect to the axis of the combustor body. A combustion device for a fuel cell system, comprising:

According to a sixth aspect of the present invention, there is provided a fuel cell system, wherein the hydrogen producing apparatus uses the combustion apparatus according to any one of the first to fifth aspects.

According to the combustion device of the fuel cell system of the present invention and the hydrogen production device using the same, the low-calorie fuel gas and the high-calorie fuel gas are ejected from the discharge section at almost the same place, Since the combustion air is supplied to the fuel gas and burned, it becomes possible to burn two types of fuel gas having different properties in the same flame hole of the combustor.

When the combustion air is supplied and burned while premixing the low-calorie fuel gas and the high-calorie fuel gas, the balance between the gas amount and the combustion air amount (air volume) is not easily lost, and the combustion is difficult. In addition to eliminating flashback in the vessel and damaging the combustion device itself,
Since the flame formation part of the fuel gas is integrated in one place, the combustion air is supplied and burned while mixing the low calorie fuel gas and the high calorie fuel gas in advance, so the flame detection of the combustor with one sensor Can be done.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an end view schematically showing a basic structure of a hydrogen production apparatus for a fuel cell (hereinafter, referred to as a reformer).

In FIG. 1, a reformer 1 includes a combustion heating chamber 2
, A cylindrical catalyst tube 4 and a reforming tube 5 outside the heating tube 3, and a reaction vessel 6 formed between the catalyst tube 4 and the heating tube 3. It is composed of a reforming catalyst 7 and the like.

The combustion chamber 8 is provided with a combustion device 9 such as a gas combustor 19 provided at a lower portion, and the combustion device 9 takes in air for combustion from an air port 10 and generates high calorie gas such as LPG and city gas. And a high-temperature combustion gas generated by burning the low-calorie off-gas to the upper part of the combustion chamber 8 and the combustion gas flowing down along the inner periphery of the heating cylinder 3. The exhaust gas is exhausted from an exhaust port 13 through the bottom of the reformer 5 and an exhaust chamber 12 on the outer periphery of the reforming cylinder 5.

The reaction vessel 6 formed between the catalyst cylinder 4 and the heating cylinder 3 has a vertically elongated cylindrical shape, and has an upper partition plate 14 having a cross section slightly lower than the upper surface and a cross section slightly higher than the lower surface. A lower partition plate 15 is provided on the surface, and a catalyst layer 16 containing a granular catalyst is formed therein.

A wire mesh or a porous plate is used for the upper and lower partition plates 14 and 15 so that gas can enter and exit the catalyst layer 16 through the holes of the partition plates. The size of the holes is smaller than the size of the catalyst particles so that the catalyst does not spill. Reference numeral 17 denotes a gas introduction pipe 17 for introducing the reforming raw material gas into the reaction vessel 6, and an inlet space 18 is formed between the gas introduction pipe 17 and the upper partition plate 14.

A combustion device 9 mounted below the heating cylinder 3 of the reformer 1 has an upper end opening of the combustion device 9 airtightly connected to a combustion chamber 8 of the reformer 1.

FIG. 2 shows such a combustion device 9 of the reformer 1.
FIG. 3 is a cross-sectional view showing one embodiment of the configuration of FIG.

The combustion device 9 comprises a flame hole 2 of a combustor 19.
A high-calorie combustion gas supply pipe 21 for supplying hydrocarbon fuel to the fuel cell system 0 and a high-calorie gas supply pipe 22 for supplying unreacted gas (off-gas) supplied to the fuel cell system to the combustor 19 are a double pipe 23. A fuel gas supply path formed in
Gas discharge portions 24 and 25 of high calorie gas and low calorie gas provided on the downstream side of these gas supply passages, a flame hole plate 26 spreading in a mortar shape around these discharge portions 24 and 25, and air It is composed of a combustion air ejection hole 27 for supplying the combustion air flowing from the port 10 to the flame hole 20.

Outer pipe 2 of double pipe 23 serving as fuel gas supply path
Numeral 8 is connected to a mortar-shaped flame hole plate 26 whose downstream end is flared in a trumpet shape. The fuel gas is diffused along the flame hole plate 26 to form a flame there.

The inner tube 29 of the double tube 23 has a downstream end 30 projecting toward the flame hole 20 by a few mm higher than the downstream end 31 of the outer tube 28, and the gas discharge to the end 30. By forming a plurality of holes 32 serving as the section 25 and providing a gas diffusion plate 33 at the downstream end of the double pipe 23, the discharge sections 24, 2
The fuel gas discharged from 5 is jetted in the circumferential direction.

By adopting such a fuel gas supply / diffusion structure, the fuel gas discharge part 24 of the outer pipe 28 and the fuel gas discharge part 25 of the inner pipe 29 meet at the center bottom of the flame hole plate 26. A gas mixing portion is formed to cause the high-calorie gas and the low-calorie gas to flow out and mix while diffusing along the flame plate 26.

The gas diffusion plate 33 has the same shape as the cross section of the flame hole plate 26 when the flame hole portion 20 has a round mortar shape. The fuel gas impinging on the diffuser plate 33 is distributed as evenly as possible to the flame hole plate 26. The flame hole portion 20 following the gas discharge portions 24, 25 has the gas discharge portions 24, 25 as the center. A mortar-shaped flame hole plate 26 is provided so that the flame holes spread in a trumpet shape, and an air ejection hole 27 is arranged at the downstream peripheral edge of the gas discharge portions 24 and 25.

The air ejection hole 27 is a hole for supplying the combustion gas supplied from the air port 10 through the air supply passage 34 to the fuel gas, and is directed outward with respect to the axis of the combustor 19 main body. It is formed radially, from which combustion air is supplied to the flame hole 20. In FIG.
By providing a large number of air ejection holes 27 on the inclined surface 6, air is supplied to the flame hole 20.

FIG. 3 is a front view of a main part of the flame hole 20 showing one embodiment of the air ejection hole 27 of such a combustion device 9 according to the present invention.

The gas discharge part 25 of the inner pipe 29 and the gas discharge part 24 of the outer pipe 28 are respectively provided at the upper end of the double cylindrical pipe, and the upper end of the inner pipe 29 has a disk-shaped gas diffusion plate 33. Is attached. Further, a mortar-shaped flame hole plate 26 is provided around the upper end edge of the outer gas supply pipe, and a large number of air ejection holes 27 are formed on the inclined surface of the flame hole plate 26. The combustion air is injected from the air ejection holes 27 to the flame holes 20 in four rows at an interval of 15 degrees outward with respect to the axis of.

In the reformer 1 configured as described above,
While the operation of the combustion device 9 is started and the reaction vessel 6 and the catalyst filled therein are heated by the high-temperature combustion gas,
When the reforming raw material gas and steam flow in from the gas introduction pipe 17, the hydrocarbon compound reacts with the steam in the catalyst layer 16, and as described above, contains hydrogen gas as a main component, carbon monoxide gas and carbon dioxide gas. Is generated.

That is, the reforming raw material gas introduced into the reaction vessel 6 of the reformer 1 is struck on the upper plate of the top of the cylinder of the reformer 1, spreads along the surface, and spreads in four directions. And flows into the catalyst layer 16. At this time, since the reforming reaction of the hydrocarbon compound by the steam is an endothermic reaction, the reforming catalyst 7 receives the reaction heat from the high-temperature combustion gas flowing through the combustion chamber 8 to perform the reforming reaction of the hydrocarbon compound. Heat is supplied, and the outside of the catalyst layer 16 is supplied with heat of reaction from the reformed gas flowing out through the reforming cylinder 5.

According to such a fuel cell system of the present invention, the low-calorie gas gas flows from the lower part through the gas supply pipe (the inner pipe 29 in FIG. 2) to the diffusion plate from the upper end gas discharge part 25, and It is diffused in the direction of the flame hole plate 26 by the diffusion plate 33, mixed with the combustion air supplied from the air ejection holes 27, and burns completely.

Similarly, high-calorie gas is supplied from the lateral portion to the gas supply pipe (the outer pipe 28 in FIG. 2), flows from the upper gas discharge section 24 toward the diffusion plate 33, Diffusion in the direction of the flame hole plate 26 and the air ejection holes 27
It is mixed with the supplied combustion air and completely burns.

As described above, in the combustion apparatus 9 of the hydrogen production apparatus of the fuel cell system according to the present invention, off-gas (low-calorie fuel gas) and high-calorie Since it is supplied with combustion air and burned while ejecting and mixing with the fuel gas of
It becomes possible to burn two types of fuel gas having different properties in the same flame hole portion 20.

When the combustion air is supplied and burned while preliminarily mixing the low calorie fuel gas and the high calorie fuel gas, the fuel gas component has a small variation, so that the gas amount and the combustion air amount (air volume) are small. ) Is hardly lost, and there is no danger of flashback in the combustor 19 or damage to the body of the combustion device 9, and since the flame forming portion of the fuel gas is integrated in one place, combustion with one sensor The flame of the vessel 19 can be detected.

FIG. 4 shows the air ratio of the carbon monoxide concentration in the exhaust gas as a result of performing a combustion test using a city gas (13A) as a fuel in a reformer having such a combustion apparatus of the present invention. It is a table showing dependency.

As shown by the curve A in the figure, it can be seen that in the conventional combustion apparatus, the concentration of carbon monoxide in the exhaust gas sharply rises only by a slight change in the air ratio, and it is difficult to adjust the combustion air. On the other hand, in the combustion device 9 of the present invention having the flame holes 20 as in the embodiment of FIG. 3 described above, the width of the control of the combustion air can be given, and the air ratio changes slightly. However, it can be seen that the increase in the concentration of carbon monoxide in the exhaust gas can be suppressed, and the adjustment of the combustion air is facilitated.

FIG. 5 is a front view of a main part of the flame hole 20 showing another embodiment of the air ejection hole 27 of the combustion apparatus 9 shown in FIGS.

In this embodiment, the shape of the air ejection holes 27 is a slit shape, and the slit holes are formed outward at intervals of 15 degrees with respect to the axis of the combustion device 9 main body. . Other configurations are the same as those in FIG.

In the combustion apparatus 9 of the hydrogen production apparatus for a fuel cell having the configuration shown in FIG. 5, both high-calorie gas and low-calorie gas can be completely burned, similarly to the first embodiment shown in FIG.

In both the combustor shown in FIG. 3 and the burner plate shown in FIG. 5, the air ejection holes 27 are formed in a mortar-shaped flame-like plate 26 which spreads in a trumpet shape. A large number of flame supply holes for air supply can be provided, and the combustion device 9 and the hydrogen production device of the fuel cell system using the same can be reduced in size as compared with a conventional flat plate-shaped one.

In the description of the embodiment shown in FIG. 3, the gas supply path has a double pipe structure in which a low calorie gas supply path is provided on the inside and a high calorie gas supply path is provided on the outside. There is no substantial difference between a gas supply path and a double pipe provided with a low-calorie gas supply path outside.

[0049]

The hydrogen production apparatus for a fuel cell system and the combustion apparatus thereof according to the present invention described above provide a high calorie combustion gas supply pipe for supplying hydrocarbon fuel to a flame hole of a combustor and a fuel cell system. A high calorie gas supply pipe formed of a double pipe with a high calorie gas supply pipe for supplying the unreacted gas (off gas) after the combustion to the combustor, and a high calorie gas provided downstream of these gas supply paths. It is provided with a gas discharge part for low calorie gas, a flame hole part spreading in a mortar shape around these discharge parts, a combustion air supply path for supplying combustion air flowing from an air port to the flame hole part, and the like. Therefore, the flame holes of the low-calorie gas gas and the high-calorie gas are common, and a low-cost combustion device and a hydrogen production device for a fuel cell system with a simplified structure can be provided.

In addition, since a low calorie gas gas and a high calorie gas are burned in the same flame hole, the combustion device and the fuel cell have a simple structure and a good controllability, such that the flame can be easily detected by a single flame detection. It becomes possible to provide a hydrogen production apparatus for the system.

Further, in this combustion apparatus, since the primary air is not supplied as in the prior art, there is no danger of flashback, and the installation of the gas diffusion plate makes the injection of the fuel gas uniform. Further, the state of formation of the flame in the combustion device becomes uniform, and the distribution of the temperature of the catalyst heating in the hydrogen production device of the fuel cell system is made uniform, thereby enabling efficient reforming.

[Brief description of the drawings]

FIG. 1 is an end view showing a schematic configuration of a hydrogen production apparatus of a fuel cell system according to an embodiment of the present invention.

FIG. 2 is a sectional view showing one embodiment of a combustion device of the hydrogen production device of the fuel cell system according to the present invention.

FIG. 3 is a cross-sectional view showing one embodiment of an air ejection portion of the combustion device of the fuel cell system according to the present invention.

FIG. 4 shows C in the exhaust gas of the combustion device of the present invention and the conventional combustion device.
It is a comparison figure of the air ratio dependence of O concentration.

FIG. 5 is a cross-sectional view showing another embodiment of the air ejection portion of the combustion device of the fuel cell system according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reformer 2 Combustion heating chamber 3 Heating cylinder 4 Catalyst cylinder 5 Reforming cylinder 7 Reforming catalyst 8 Combustion chamber 9 Combustion device 10 Air port 11 Combustion guide cylinder 16 Catalyst layer 17 Gas introduction pipe 19 Combustor 20 Flame hole 21 High-calorie gas supply pipe 22 Low-calorie gas gas supply pipe 23 Double pipe 24 Gas discharge unit 25 Gas discharge unit 26 Flame plate 27 Air ejection hole 32 Hole serving as gas discharge unit 33 Gas diffusion plate 34 Air supply path

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 8/06 H01M 8/06 G (72) Inventor Akira Fujio 2-5-5 Keihanhondori, Moriguchi-shi, Osaka 5 No. 5 Sanyo Electric Co., Ltd. (72) Inventor Yo Hamada 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 3K019 AA05 BA03 BB04 BD08 BD09 CA02 3K065 QB11 QC03 RA02 3K091 AA20 BB26 CC06 CC07 CC25 4G040 EA03 EA06 EB04 EB14 EB23 5H027 AA02 BA09

Claims (6)

[Claims] 1. A combustor for burning a hydrocarbon-based high-calorie gas and a low-calorie gas obtained from off-gas of a fuel cell, wherein the combustion device includes a discharge section for the low-calorie gas or the high-calorie gas at a center. A gas mixing portion of high calorie gas and low calorie gas around the discharge portion, and a flame hole portion spreading in a mortar shape around the discharge portion and the gas mixing portion. A combustion device for a fuel cell system, comprising: 2. A high calorie gas supply path for supplying a high calorie gas to the flame hole and a low calorie gas supply path for supplying a low calorie gas have a double pipe structure. 3. The combustion device for a fuel cell system according to claim 1. 3. The combustion device for a fuel cell system according to claim 1, wherein the flame hole portion has a structure in which an air ejection hole is provided in a mortar-shaped flame hole plate. 4. The flame hole has a gas diffusion plate having a shape similar to the cross section of the flame hole at a downstream end of an inner pipe of a gas supply path having a double pipe structure. The combustion device for a fuel cell system according to any one of claims 1 to 3, wherein: 5. A large number of pores or slit-shaped air ejection holes are formed radially outward with respect to the axis of the combustor main body on the inclined surface of the mortar-shaped flame hole plate of the flame hole portion. The combustion device for a fuel cell system according to claim 3 or 4, wherein: 6. A hydrogen production device for a fuel cell system using the combustion device according to claim 1.