JP2005180812A - Burner and reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burner and a reformer that can secure good maintainability, reduce the space required, and be made compact, the burner vaporizing liquid fuel using a heating surface. <P>SOLUTION: The burner that burns liquid fuel by vaporizing it and mixing it with an oxygen-containing gas comprises a casing provided with an oxygen-containing gas inlet and having an opening at its lower end; a nozzle through which the liquid fuel flows down into the casing; and a heating surface provided inside the casing for vaporizing the liquid fuel that flowed down. The burner has a burner mat provided at or downstream of the opening and has a nozzle downstream of the burner mat for supplying a hydrogen-electrode off-gas. The reformer that provides a reformed gas by reforming raw materials for manufacture of hydrogen has the reformer burner that supplies heat for a reforming reaction by vaporizing liquid fuel, mixing it with an oxygen-containing gas, and burning the mixture. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a burner that vaporizes and burns liquid fuel such as kerosene. In particular, the present invention relates to a burner for supplying heat necessary for a reformer used in a fuel cell system. The present invention also relates to a reformer for reforming a raw material for hydrogen production to obtain a reformed gas containing hydrogen.

  In a small burner that uses liquid fuel as a fuel, such as used in a reformer of a fuel cell system, it is difficult to diffuse and burn the fuel by pressure spraying. For this reason, in such a burner, after vaporizing the fuel, it is mixed with air (primary air) and then burned using a burner head having a plurality of flame holes.

In order to vaporize the liquid fuel, the liquid fuel is generally supplied dropwise to a cup-like container heated by an electric heater, called a vaporizer, which is heated to a temperature sufficient to vaporize the liquid fuel. In contact with the heated surface (inner wall of the container). The burner used in the fuel cell system has a structure in which a hydrogen electrode off gas nozzle is provided in the vicinity of the burner head for burning the liquid fuel so that the hydrogen electrode off gas can be combusted. Such a structure of the burner for liquid fuel is described in, for example, Japanese Patent Application Laid-Open No. 7-237902.
JP 7-237902 A

  Thus, in the small burner for liquid fuel, since the flow rate of the liquid fuel is small, it is difficult to stably supply the liquid fuel by spraying. For this reason, liquid fuel is supplied by flowing down from a pipe (nozzle) whose tip is narrowed. Since liquid fuel falls vertically downward from the nozzle tip, in a conventional vaporizer using a cup-like container, a vaporizer wall surface (heating surface) is provided vertically below the nozzle tip. For this reason, the opening of the vaporizer is vertically upward or laterally (horizontal), and therefore the flame formation direction is limited to upward or laterally.

  For example, when a reformer in a fuel cell system is provided with a burner in which a flame is formed upward, a space for flame formation is required in the upper part, so that the burner is usually arranged at the lowermost part of the reformer. It is necessary to perform maintenance by removing the burner, etc. However, if the burner is attached at the bottom like this, it is difficult to secure space for maintenance, and if priority is given to securing maintenance space, it is usually Space is wasted during operation, and the device becomes large. The same applies when the flame direction is horizontal.

  SUMMARY OF THE INVENTION An object of the present invention is to achieve space saving and compactness while ensuring good maintainability in a burner that vaporizes liquid fuel by a hot surface.

  Another object of the present invention is to provide a reformer that has good burner maintainability, and can be space-saving and compact.

In the burner according to the present invention, the liquid fuel is vaporized and mixed with the oxygen-containing gas and burned.
A casing having an opening at the lower end provided with an oxygen-containing gas inlet;
A burner comprising: a liquid fuel nozzle for flowing liquid fuel into the casing; and a vaporizer provided in the casing and having a heating surface for vaporizing the flowed liquid fuel. Provided.

In the burner, the liquid fuel nozzle is provided substantially vertically downward,
The heating surface is provided substantially horizontally below the liquid fuel nozzle,
It is preferable that a gap is provided between the heating surface and the casing so that vaporized fuel can reach the opening.

  In the burner, it is preferable that the flow path in which the mixed gas of the vaporized liquid fuel and the oxygen-containing gas flows is changed in the direction of 1 to 4 times.

  The burner preferably further includes a burner mat for burning the vaporized liquid fuel derived from the opening at a position covering the opening or below the opening.

  In the burner, the burner mat is preferably made of a woven or non-woven metal fiber.

In the burner, it is preferable that the combustion amount of the liquid fuel per unit area of the burner mat is 200 kW / m ² or more and 4500 kW / m ² or less.

  In the burner, the combustion amount is preferably 8.1 kW or less.

According to the present invention, a reformer used in a fuel cell system for reforming a raw material for hydrogen production to obtain a reformed gas containing hydrogen is vaporized and mixed with an oxygen-containing gas and burned. In a reformer burner for supplying heat for quality reaction,
A casing having an opening at the lower end provided with an oxygen-containing gas inlet;
A liquid fuel nozzle for flowing liquid fuel into the casing; and a vaporizer provided in the casing having a heating surface for vaporizing the flowed liquid fuel;
A burner mat for burning the vaporized liquid fuel derived from the opening at a position covering the opening or below the opening;
A reformer burner comprising a hydrogen electrode off-gas nozzle for supplying a hydrogen electrode off-gas of a fuel cell downstream of the burner mat is provided.

According to the present invention, a reformer for reforming a raw material for hydrogen production to obtain a reformed gas containing hydrogen, which vaporizes liquid fuel, mixes it with an oxygen-containing gas, and burns it for reforming reaction. In a reformer comprising a reformer burner for supplying heat,
The reformer burner is
A casing having an opening at the lower end provided with an oxygen-containing gas inlet;
A reformer comprising: a liquid fuel nozzle for flowing liquid fuel into the casing; and a vaporizer provided in the casing and having a heating surface for vaporizing the flowed liquid fuel. A vessel is provided.

  According to the present invention, in the burner that vaporizes the liquid fuel by the heating surface, the flame can be formed vertically downward, so that the burner can be arranged on the upper part of the equipment such as a reformer to which the burner is attached, and therefore In particular, without providing a space for maintenance, the burner can be easily accessed from above the reformer or the like. In this way, a burner capable of achieving both maintainability and compactness can be obtained, and compactness can be achieved including an apparatus equipped with the burner or its installation space. Compactness is an important factor in household hot water supply or heating equipment, and particularly in fuel cell systems, and the burner of the present invention can be suitably used in such equipment.

  Moreover, the reformer of the present invention provided with such a burner has good maintainability, can save space and can be made compact, and is suitable for a hydrogen production apparatus and a fuel cell system.

  As the liquid fuel, a combustible substance that is liquid at normal temperature and normal pressure (25 ° C., 0.101 MPa) can be used as appropriate. For example, compounds having carbon and hydrogen in the molecule such as hydrocarbons and alcohols can be used. Preferable examples that can be obtained at low cost for industrial use or consumer use include methanol, ethanol, gasoline, kerosene, and light oil. Of these, kerosene is preferable because it is easily available for industrial use and consumer use, and is easy to handle.

  Air (atmosphere) is preferable as the oxygen-containing gas used for combustion in the burner, but oxygen-enriched air with an increased oxygen concentration can also be used, and in the fuel cell system, the air electrode of the fuel cell is used. The cathode off-gas discharged from the (cathode) can also be used.

  Hereinafter, although the form of this invention is demonstrated using drawing, this invention is not limited to these. Further, air will be described as an example of the oxygen-containing gas.

  FIG. 1 shows an embodiment of a vaporizer used in the burner of the present invention. The carburetor casing 2 has a cylindrical shape whose outer shape has a central axis in the vertical direction, and has an air inlet 4 on the upper surface and an opening 3 on the lower end. A liquid fuel nozzle 1 is provided substantially vertically downward through an air inlet so that liquid fuel can be supplied from the outside. In the carburetor casing, a heating surface 5 is provided substantially horizontally below the liquid fuel nozzle. The heating surface is integrated with the vaporizer casing, and can be heated to a temperature suitable for vaporizing the liquid fuel by heat conduction from the electric heater 6 embedded in the vaporizer casing.

  The liquid fuel flowing down from the liquid fuel nozzle contacts the heating surface 5 and vaporizes. The liquid fuel may be dropped intermittently from the nozzle, but it is preferable that the liquid fuel is continuously flowed from the viewpoint of making the concentration of the fuel in the air-fuel mixture more constant. From the viewpoint of stably and continuously flowing down the liquid fuel, it is preferable that the discharge speed of the liquid fuel from the nozzle is 5 cm / second or more. Moreover, it is preferable to set it as 60 cm / sec or less from a viewpoint of the pressure loss of liquid feeding. In order to adjust the discharge speed in this way, the liquid fuel may be supplied to the liquid fuel nozzle after the flow rate is adjusted to this range by a flow rate adjusting means such as a flow rate adjusting valve or a metering pump.

  Although the liquid fuel nozzle can be provided in a direction other than substantially vertically downward, for example, horizontally, the nozzle itself is substantially vertical from the viewpoint of suppressing the formation of relatively large droplets and making the fuel concentration in the mixture more constant. It is preferable to face downward. “Substantially vertically downward” means that the extending direction of the nozzle does not necessarily have to be strictly vertically downward, and the deviation from the vertically downward is preferably within 10 °, more preferably within 5 °. Preferably, it is more preferably within 3 °.

  At least at the tip of the liquid fuel nozzle, the liquid fuel nozzle is in the air flow path, and the liquid fuel nozzle and the air flow direction are preferably oriented in the same direction, and the liquid fuel nozzle and the air inlet are coaxial. More preferably. For example, as shown in FIG. 1, a configuration in which the tip of the liquid fuel nozzle faces vertically downward and the central axis of the cylindrical air inlet and the central axis of the liquid fuel nozzle coincide is preferable. This is because the air flow has the effect of removing the liquid fuel from the nozzle tip, suppresses the large growth of droplets at the nozzle tip, and the liquid fuel concentration in the mixture becomes more constant. .

  It is preferable that the heating surface is substantially horizontal so that the liquid fuel that has been subjected to the enemy diffuses uniformly. “Substantially horizontal” means that the heating surface does not necessarily have to be exactly horizontal, and the deviation from the horizontal is preferably within 10 °, more preferably within 5 °, and more preferably within 3 °. More preferably.

  In addition, the heating surface is preferably circular so that the liquid fuel after dripping diffuses uniformly.

  The heating surface can also be formed integrally with the vaporizer casing. For example, a hollow cylindrical portion that forms the outer wall of the vaporizer and a plate-like portion that forms the heating surface can be formed integrally. Alternatively, for example, a plate-like member having a surface to be a heating surface can be joined to the vaporizer casing by welding or the like. The vaporizer can have a portion for embedding the heater, a convex portion, or the like.

  The member having the heating surface and the material of the vaporizer casing are preferably metal from the viewpoint of thermal conductivity. For example, aluminum or brass is suitable.

  The temperature of the heating surface can be appropriately set according to the type of liquid fuel to be supplied. For example, when the liquid fuel is kerosene, it is preferably 180 ° C. or higher and 250 ° C. or lower, more preferably 190 ° C. or higher and 220 ° C. or lower. This is disadvantageous in that it is near the initial distillation temperature of kerosene below 180 ° C., so the vaporization rate of the high boiling point component is slow, the fuel concentration in the mixture tends to be unstable, and the flame tends to become unstable. In addition, when the temperature exceeds 250 ° C., the dropped liquid droplet is covered with vaporized fuel vapor, so that a so-called film boiling state occurs, the vaporization speed becomes slow, the fuel concentration in the mixture becomes unstable, and the flame becomes unstable. This is disadvantageous in that it tends to be, and this is to avoid such a situation.

  Combustion air is introduced vertically downward from the air inlet 4 and collides with the heating surface while mixing with the vaporized liquid fuel. The flow path of the air-fuel mixture of combustion air and liquid fuel turns 90 ° on the heating surface, becomes horizontal along the heating surface, and then turns 90 ° again by the side wall of the vaporizer casing 2 for mixing. The gas passes through a gap 7 between the heating surface and the side wall of the vaporizer casing. The flow path of the air-fuel mixture is changed by 90 ° by the convex portion 8 on the inner wall of the vaporizer casing, and further changed by 90 ° toward the opening 3 by the side wall of the vaporizer casing. In this way, the flow of the air-fuel mixture is changed four times, thereby promoting the mixing of the air and the vaporized liquid fuel. The direction change of four times is not necessarily required and the angle of the direction change may not necessarily be 90 °. However, from the viewpoint of promoting the mixing, the flow path of the air-fuel mixture is preferably changed at least once. More preferably, the direction is changed more than once. In addition, the number of times of changing the direction of the air-fuel mixture is preferably 4 times or less from the viewpoint of suppressing the complexity of the apparatus. The white arrow in FIG. 1 shows a state of changing the direction of the mixture flow path.

  It is preferable that the gaps serving as the air-fuel mixture flow path in the carburetor are arranged approximately symmetrically from the viewpoint of preventing the drift of the mixed air flow.

  If the combustion air introduction port 4 is provided on the upper surface of the carburetor casing, the combustion air is supplied downward from this and the heating surface is formed in a substantially horizontal direction, the air-fuel mixture is provided above the heating surface. When the air-fuel mixture collides with the heating surface, the air-fuel mixture flow path is turned once. Further, if the air-fuel mixture passes through the gap between the heating surface and the vaporizer casing and reaches the opening 3, the direction change is performed at least once.

  The electric heater has a function of supplying heat for preheating the combustion air in addition to supplying heat for vaporizing the liquid fuel. The combustion air is preheated by heat exchange with a carburetor casing or the like. In some cases, it is possible to preheat the fuel air separately before supplying it to the burner. When the combustion air is sufficiently preheated separately, it is possible to eliminate the electric heater for heating the vaporizer, but it is preferable to use an electric heater as a heating means from the viewpoint of temperature controllability.

  The combustible mixed gas derived from the opening 3 can be appropriately ignited and burned by an igniter or the like. Since the lead-out direction of the mixed gas is vertically downward, the flame is also formed vertically downward. For this reason, the burner can be placed on the upper part of equipment such as a reformer to which the burner is attached, and access to the burner becomes easier during maintenance than when the burner is placed on the lower part of the equipment. Thus, it is possible to save space while ensuring good maintainability as a whole device.

  In order to adjust the derived direction of the mixed gas vertically downward, the length of the portion directly facing the opening 3 of the flow path can be adjusted, or a rectifier can be provided.

  In order to improve combustion stability, a flame holder can be provided on the downstream side of the opening 3.

  Further, it is preferable to burn the combustible mixed gas using a burner mat because the combustion stability is excellent even if the combustion amount is small.

As the burner mat, a non-woven fabric or woven fabric of metal fibers, or a non-woven fabric or woven fabric of fibers made of ceramics such as cordierite, titania, mullite, alumina, silica, and alumina-silica can be used. A punching plate can also be used. From the viewpoint of heat uniformity and prevention of backfire, a mat made of woven or non-woven metal fibers is preferable as the burner mat. In addition, when the burner mat is a woven fabric or a non-woven fabric, since the opening ratio is larger than that of a punching plate or the like, the speed of the air-fuel mixture when passing through the burner mat becomes slow. For this reason, for example, in a low combustion region of about 200 kW / m ² , a flame is formed in the vicinity of the burner mat, and the burner mat is immediately red hot by the flame, so that good combustion stability is obtained. In addition, in a high combustion range of, for example, about 4500 kW / m ^2, the speed of the air-fuel mixture passing through the burner mat is relatively slow, so that flame blow-off can be suppressed.

Combustion amount of vaporized liquid fuel per unit area of the burner mat, preferably 200 kW / m ² or more in terms of combustion stability, and more preferably from 600 kW / m ² or more, 1000 kW / m ² or more is more preferable. Further, from the viewpoint of the flame blown off suppression, preferably 4500kW / m ² or less, more preferably 4000 kW / m ² or less, more preferably 3500kW / m ² or less. For this purpose, a burner mat having an area suitable for realizing such a range with respect to the combustion range required by the device may be provided.

  The burner of the present invention is particularly suitable for a burner with a small combustion amount. This is because a burner of a type in which liquid fuel is vaporized by a heating surface and burned is suitable for a burner with a small combustion amount, and particularly combustion with a burner mat can be stably burned even with a small combustion amount. This is also because there is a strong demand for compactness in such a small combustion amount burner. Specifically, the effect of the present invention is remarkable in a burner having a maximum combustion amount of 8.1 kW (7000 kcal / h) or less, and in a burner having a maximum value of 5.8 kW (5000 kcal / h) or less.

  When the burner of the present invention is mounted on a reformer in a fuel cell system, the burner is effectively used from the viewpoint of effectively using the hydrogen electrode off-gas of the fuel cell (the hydrogen electrode of the fuel cell, ie, the combustible gas discharged from the anode). It is preferable to supply a hydrogen electrode off-gas downstream of the mat and burn it. After ignition of the hydrogen electrode off-gas, all of the liquid fuel, combustion air, and hydrogen electrode off-gas can be supplied to burn both the liquid fuel and the hydrogen electrode off-gas simultaneously. For example, liquid fuel can be vaporized and combusted at the start of the fuel cell system, and after the start of power generation, the use of liquid fuel can be reduced to co-firing, or the liquid fuel supply can be stopped to combust only the hydrogen off-gas. .

  A form of a fuel reforming burner suitable for such an application is shown in FIG. The basic structure of this burner is the same as that shown in FIG. However, the burner mat 13 is disposed at a position covering the lower end opening of the vaporizer casing 2. Further, the hydrogen electrode off-gas is supplied from the hydrogen electrode off-gas inlet 18 and passes through a flow passage having an annular cross section provided outside a flow passage of secondary air, which will be described later, and is downstream of the burner mat (flame) from the hydrogen electrode off-gas nozzle 18a. Supplied to the holding surface side). The burner preferably has a structure in which the hydrogen electrode off-gas can be ignited by the flame of the liquid fuel formed downstream of the burner mat, but the liquid fuel may be blown off by excessive off-gas injection at the time of switching. For this reason, it is desirable that the hydrogen electrode off gas nozzle be installed at a position where the hydrogen electrode off gas can be ignited by the igniter 19 for igniting the liquid fuel mixture. Further, as described above, since the hydrogen electrode off gas contains, for example, 20 mol% to 50 mol% of hydrogen that tends to form an explosive mixture, diffusion combustion without premixing with air is preferable. A structure for direct ejection is preferred. In FIG. 2, a burner mat is provided in contact with the vaporizer casing at a position covering the opening. However, a burner mat can be provided below the opening 3. For example, an extension cylinder, which is a hollow cylindrical member for forming a gas mixture flow path, is disposed between the vaporizer casing opening and the burner mat, and the gas exiting the opening 3 passes through the extension cylinder. Alternatively, the configuration may reach the burner mat. The burner mat is provided substantially horizontally so that the flame can be formed facing downward, and the air-fuel mixture is supplied from the upper surface of the burner mat. By providing the extension cylinder in this manner, the distance between the flame and the vaporizer (particularly the heating surface) can be easily adjusted, and the temperature control of the heating surface may be facilitated.

  Further, on the upstream side of the burner mat, a rectifier 12 is provided for adjusting the flow of the air-fuel mixture supplied to the burner mat and making the combustion uniform. In the rectifier, the horizontal cross-sectional area gradually increases toward the bottom, and the opening at the lower end is substantially the same as the shape of the burner mat. The rectifier has a funnel shape as a whole.

  A cylindrical flame holding ring 14 extending in the vertical direction is provided on the downstream side of the burner mat. The flame holding ring has an effect of improving flame stability. For example, it is possible to prevent a phenomenon in which a hydrogen electrode off-gas or secondary air, which will be described later, is directly blown onto a flame of a burner mat and the flame is blown off. Further, since the flame holding ring is provided in contact with the vaporizer casing, the flame holding ring is heated by the flame, and the heat is conducted to the vaporizer casing to heat the vaporizer casing. For this reason, the size of the flame holding ring is determined by the amount of heat recovery required.

  The burner mat is sandwiched between the rectifier and the flame holding ring.

  Combustion air is introduced from the combustion air supply pipe inlet 16 and supplied from the air inlet 4 into the carburetor casing. Separately, the secondary air is introduced from the secondary air inlet 17 and supplied to the downstream of the burner mat from the secondary air nozzle 17a through the annular cross-sectional flow path provided outside the vaporizer casing. Promotes complete combustion.

  The thermocouple 11 is for measuring the temperature of the vaporizer in order to control the temperature of the heating surface within an appropriate range by operating the output of the electric heater.

  As a method of using such a burner, for example, the electric heater 6 is operated to heat the heating surface, and the air is boosted by a gas boosting means such as a blower as necessary, and the combustion air supply pipe inlets 16 and 2 are used. After supplying from the next air inlet 17 and the heating surface reaches a predetermined temperature, the liquid fuel is boosted by a liquid boosting means such as a pump as needed to cause the liquid fuel to flow down from the liquid fuel nozzle 1 and an igniter 19 or the like. The ignition means may be activated. When burning the hydrogen electrode off-gas, the hydrogen electrode off-gas can be boosted by a gas booster such as a blower and supplied to the hydrogen electrode off-gas inlet 18 as necessary.

[Reformer]
FIG. 3 shows an example in which this burner 101 is attached to a reformer 102 used in a fuel cell system. The burner is attached to the top of the reformer and is accessible from above.

  The reformer is an apparatus for producing a reformed gas containing hydrogen by reacting a raw material for hydrogen production with water and / or oxygen. In this apparatus, the raw material for hydrogen production is mainly decomposed into hydrogen and carbon monoxide. Usually, carbon dioxide and methane are also contained in the cracked gas. Examples of the decomposition reaction include a steam reforming reaction and an autothermal reforming reaction. The steam reforming reaction involves a large endotherm, and a burner or the like is used to supply heat for this purpose from the outside. Even in the autothermal reforming reaction, heat may be supplied from the outside in some cases. The burner of the present invention can be suitably used for a so-called external heat reformer that supplies heat from the outside as described above. Inside the reformer, a reforming tube 102a containing a catalyst capable of promoting a reforming reaction such as a steam reforming reaction is disposed inside, and this reforming tube is heated by the combustion heat of the burner, and the reforming reaction is performed. Heat is supplied to advance the process.

  The raw material for hydrogen production can be appropriately selected from substances that can obtain a reformed gas containing hydrogen by a steam reforming method or an autothermal reforming method. For example, compounds having carbon and hydrogen in the molecule such as hydrocarbons, alcohols and ethers can be used. Preferable examples that can be obtained inexpensively for industrial use or consumer use include methanol, ethanol, dimethyl ether, city gas, LPG (liquefied petroleum gas), gasoline, kerosene and the like. Of these, kerosene is preferable because it is easily available for industrial use and consumer use, and is easy to handle. The liquid fuel supplied to the burner may be different from the raw material for hydrogen production, but the same one is preferably used from the viewpoint of compactness. This is because a storage means such as a tank for these and a supply system such as a pump can be used together.

The steam reforming reaction is a reaction between steam and hydrocarbons, but usually involves heating from the outside because it involves a large endotherm. Usually, the reaction is carried out in the presence of a metal catalyst typified by a Group VIII metal such as nickel, cobalt, iron, ruthenium, rhodium, iridium and platinum. The reaction temperature can be 450 ° C to 900 ° C, preferably 500 ° C to 850 ° C, more preferably 550 ° C to 800 ° C. The amount of steam introduced into the reaction system is defined as the ratio of the number of moles of water molecules to the number of moles of carbon atoms contained in the raw material for hydrogen production (steam / carbon ratio), and this value is preferably 0.5-10. Preferably it is 1-7, More preferably, it is 2-5. When the raw material for hydrogen production is liquid, the space velocity (LHSV) at this time is A / B when the flow rate in the liquid state of the raw material for hydrogen production is A (L / h) and the volume of the catalyst layer is B (L). This value is preferably set in the range of 0.05 to 20 h ⁻¹ , more preferably 0.1 to 10 h ⁻¹ , and still more preferably 0.2 to 5 h ⁻¹ .

  Autothermal reforming is a method of reforming while maintaining a balance of reaction heat by advancing the steam reforming reaction with the heat generated at this time while oxidizing part of the raw material for hydrogen production. In recent years, it has attracted attention as a method for producing hydrogen for fuel cells because it has a short start-up time and is easy to control. Also in this case, the reaction is usually carried out in the presence of a metal catalyst, typically a Group VIII metal such as nickel, cobalt, iron, ruthenium, rhodium, iridium and platinum. The amount of steam introduced into the reaction system is preferably 0.3 to 10, more preferably 0.5 to 5, and still more preferably 1 to 3 as a steam / carbon ratio.

  In autothermal reforming, oxygen is added to the raw material in addition to steam. The oxygen source may be pure oxygen, but in many cases air is used. Usually, oxygen is added to such an extent that it can generate an amount of heat that can balance the endothermic reaction associated with the steam reforming reaction, but the amount added is appropriately determined in relation to heat loss and the amount of external heating by the burner. The amount is preferably from 0.05 to 1, more preferably from 0.1 to 0.75, even more preferably as the ratio of the number of moles of oxygen molecules to the number of moles of carbon atoms contained in the raw material for hydrogen production (oxygen / carbon ratio). Is set to 0.2 to 0.6. The reaction temperature of the autothermal reforming reaction is set in the range of 450 ° C. to 900 ° C., preferably 500 ° C. to 850 ° C., more preferably 550 ° C. to 800 ° C., as in the case of the steam reforming reaction. When the raw material for hydrogen production is liquid, the space velocity (LHSV) at this time is preferably selected in the range of 0.1 to 30, more preferably 0.5 to 20, and still more preferably 1 to 10.

  To control the reaction temperature, for example, the temperature of the reaction region is detected by a thermocouple, etc., the amount of liquid fuel supplementarily supplied to the burner is increased, the combustion air is increased, the hydrogen in the fuel cell Means such as increasing or decreasing the amount of hydrogen contained in the hydrogen electrode off-gas by changing the amount used is used.

[Fuel cell system]
An outline of an example of a fuel cell system having a reformer equipped with this burner is shown in FIG. The fuel cell system includes a burner 101, a reformer 102 that performs a steam reforming reaction using the combustion heat of the burner, and a fuel cell in which a reformed gas containing hydrogen obtained by the reformer is supplied to a hydrogen electrode. 103.

  As the fuel cell 103, a fuel cell of a type in which hydrogen is a reactant of electrode reaction at the hydrogen electrode can be appropriately employed. For example, a fuel cell of a solid polymer type, a phosphoric acid type, a molten carbonate type, or a solid oxide type can be employed.

  For example, a solid polymer fuel cell is composed of a hydrogen electrode (anode) 103a and an air electrode (cathode) 103c and a solid polymer electrolyte sandwiched between them, and a reformed gas (hydrogen-containing gas) is placed on the hydrogen electrode side. An oxygen-containing gas such as air is introduced to the pole side after appropriate humidification treatment if necessary. Since a combustible component remains in the hydrogen electrode off-gas discharged from the hydrogen electrode, the hydrogen electrode off-gas is supplied to the burner 101 and burned.

  When the fuel cell system is started, the liquid fuel is vaporized and burned with combustion air, and this heat can be used to warm up the reformer and other devices. After the start-up, the hydrogen off-gas is burned in the burner and the liquid fuel does not have to be burned. In some cases, the hydrogen electrode off-gas and the liquid fuel can be combusted simultaneously.

  Various devices that can be used in the fuel cell system can be provided as appropriate. For example, a reforming gas line between the reformer 102 and the fuel cell 103 can be provided with a CO shift reactor that reduces the CO concentration in the reformed gas and a selective oxidation reactor that further reduces the CO concentration. . A desulfurizer that reduces the concentration of sulfur in the raw material for hydrogen production can also be provided upstream of the reformer. In addition to this, a means for supplying oxygen-containing gas such as air to the air electrode of the fuel cell, a steam generator for generating steam for humidifying the gas supplied to the fuel cell, and various devices such as the fuel cell are cooled. Cooling system, pressurizing means such as pumps, compressors and blowers for pressurizing various fluids, flow regulating means such as valves for regulating the flow rate of fluids, or shutting off / switching the flow of fluids Channel shut-off / switching means, heat exchanger for heat exchange / recovery, vaporizer for vaporizing liquid, condenser for condensing gas, heating / heat-retaining means for externally heating various devices with steam, etc. Examples include storage means, instrumentation air and electrical systems, control signal systems, control devices, and output and power electrical systems.

  The burner of the present invention can be widely used when burning liquid fuel. In particular, it is excellent in space saving and compactness, and can be suitably used for, for example, a domestic hot water heater and a heating appliance, and can be suitably used for a fuel cell system for a moving body such as an automobile or for small-scale power generation.

  The reformer burner of the present invention can efficiently use the hydrogen electrode off-gas in addition to space saving and can be suitably applied to the reformer provided in the fuel cell system as described above.

  The reformer of the present invention is excellent in space saving and compactness, and can be suitably used in the fuel cell system as described above.

It is a schematic diagram which shows an example of the burner of this invention, (a) is a vertical sectional view, (b) is an A-A 'arrow directional view. It is a fragmentary sectional view which shows another example of the burner of this invention. It is a schematic diagram which shows the reformer equipped with the burner of this invention. It is a block diagram which shows the outline of the fuel cell system which has a reformer equipped with the burner of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid fuel nozzle 2 Vaporizer casing 3 Vaporizer casing opening 4 Air inlet 5 Heating surface 6 Electric heater 7 The space | gap between a heating surface and a vaporizer casing side wall 8 Vaporizer casing convex part 11 Thermocouple 12 Rectifier 13 Burner Matt 14 Flame holding ring 16 Combustion air supply pipe inlet 17 Secondary air inlet 17a Secondary air nozzle 18 Hydrogen electrode off gas inlet 18a Hydrogen electrode off gas nozzle 19 Igniter 101 Burner 102 Reformer 102a Reforming reaction tube 103 Fuel cell 103a Hydrogen Pole 103c Air pole

Claims (9)

In a burner where liquid fuel is vaporized and mixed with an oxygen-containing gas and burned,
A casing having an opening at the lower end provided with an oxygen-containing gas inlet;
A burner comprising: a liquid fuel nozzle for flowing liquid fuel into the casing; and a vaporizer provided in the casing and having a heating surface for vaporizing the flowed liquid fuel. The liquid fuel nozzle is provided substantially vertically downward,
The heating surface is provided substantially horizontally below the liquid fuel nozzle,
The burner according to claim 1, wherein an air gap is provided between the heating surface and the casing so that vaporized fuel can reach the opening.   The burner according to claim 1 or 2, wherein the flow path in which the mixed gas of the vaporized liquid fuel and the oxygen-containing gas flows is changed in the direction of 1 to 4 times. The burner according to any one of claims 1 to 3, further comprising a burner mat for burning the vaporized liquid fuel derived from the opening at a position covering the opening or below the opening.   The burner according to claim 4, wherein the burner mat is made of a woven or non-woven metal fiber. The burner according to claim 4 or 5, wherein a combustion amount of the liquid fuel per unit area of the burner mat is 200 kW / m ² or more and 4500 kW / m ² or less.   The burner according to any one of claims 1 to 6, wherein the combustion amount is 8.1 kW or less. A reformer used in a fuel cell system, which reforms a raw material for hydrogen production to obtain a reformed gas containing hydrogen, vaporizes liquid fuel, mixes it with an oxygen-containing gas, and burns it for reforming reaction. In the reformer burner for supplying heat,
A casing having an opening at the lower end provided with an oxygen-containing gas inlet;
A liquid fuel nozzle for flowing liquid fuel into the casing; and a vaporizer provided in the casing having a heating surface for vaporizing the flowed liquid fuel;
A burner mat for burning the vaporized liquid fuel derived from the opening at a position covering the opening or below the opening;
A reformer burner comprising a hydrogen electrode off-gas nozzle for supplying a hydrogen electrode off-gas of a fuel cell downstream of the burner mat. A reformer that reforms a raw material for hydrogen production to obtain a reformed gas containing hydrogen, vaporizes liquid fuel, mixes it with an oxygen-containing gas, burns it, and supplies heat for the reforming reaction In a reformer comprising a reformer burner for
The reformer burner is
A casing having an opening at the lower end provided with an oxygen-containing gas inlet;
A reformer comprising: a liquid fuel nozzle for flowing liquid fuel into the casing; and a vaporizer provided in the casing and having a heating surface for vaporizing the flowed liquid fuel. vessel.

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