JP2003002607A - Fuel reforming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To start to operate a fuel reforming system efficiently and quickly. SOLUTION: This invention is a fuel reforming system composed of a reforming unit to contain and install a reforming catalyst and to produce a reformed gas, and of a drive source to generate drive force by using the reformed gas discharged from the reforming unit. The reforming unit is designed to exchange heat with the gas discharged from the drive source to obtain a necessary quantity of heat for a reforming reaction. The system is also provided with a reforming unit for starting operation installed on the upstream of the above reforming unit, which, at the start of operation, forms a hydrogen-rich gas by being heated electrically and supplied with a fuel and air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel reforming system, and more particularly to improving the startability of a fuel reforming system.

[0002]

2. Description of the Related Art As a conventional fuel reforming system, for example, there is one disclosed in Japanese Patent Laid-Open No. 6-227801 as shown in FIG. This is a fuel reformer containing a fuel reforming section consisting of a reforming catalyst that produces hydrogen-rich reformed gas from fuel gas. It is a structure formed of a catalyst supporting plate supporting a catalyst and a fuel gas passage layer for allowing a fuel gas to pass through on the reforming catalyst supporting surface side of the catalyst supporting plate.

Electric power is supplied to the catalyst carrying plate from the electrode terminals provided in the structure, so that the catalyst carrying plate generates electric resistance heat, and when the reformer is started, this heat is used to reform the reforming reaction section. The temperature of the combustion gas of the combustor that heats the engine to raise the temperature to the reforming reaction temperature and starts the reforming reaction, and that is the engine exhaust temperature that is the heat source of the reforming reaction during normal operation or the exhaust gas of the fuel cell. It is disclosed that the reforming reaction is maintained by heating the reforming reaction part to a temperature at which the reforming reaction can be maintained.

As another conventional technique, there is a structure in which hydrogen rich gas is supplied to an engine and the exhaust heat of the engine is used as a heat source for fuel reforming. In this configuration, at the time of startup, the hydrocarbon-based fuel that is the reforming raw fuel is directly supplied to the engine to start the engine, and the engine exhaust heat is used to warm up the reforming system. Next, when the warm-up of the reforming system is completed, that is, when the temperature rises to a reformable state, the raw fuel is reformed and the engine operation is switched to the reformed gas.

Further, there is a configuration in which a hydrogen rich gas is supplied to a fuel cell and a combustor for burning exhaust gas of the fuel cell is provided, and the combustion gas of the combustor is used as a heat source for fuel reforming. With this configuration, when the combustor is started, the hydrocarbon fuel is directly supplied to warm up the reforming system by using the combustion heat of the combustion gas from the combustor, and the reformer is heated to the reforming reaction state. At times, generation of reformed gas is started, and the combustor is switched to operation with exhaust gas from the fuel cell.

[0006]

However, in the fuel cell system described in Japanese Patent Laid-Open No. 6-227801, the structure constituting the fuel reformer is heated at the time of startup as an electric resistor to maintain the reforming reaction. It is configured to heat up to the state, and depending on the heat capacity of the reformer, the starting time becomes long and the load on the battery or the capacitor becomes large. Furthermore, since the electric heating function becomes hot even when the reformer does not use the electric heating function, the electric heating function is likely to fail, and if the electric heating function fails, it is necessary to repair or replace the reformer. It becomes an operational problem.

In the case of supplying hydrocarbon fuel to the engine or the combustor when the system is started, the components of the exhaust gas discharged from the starting engine or the combustor are the same as those of the exhaust gas of a normal gasoline engine. However, the purified exhaust gas cannot be discharged even though the system is capable of supplying hydrogen-rich gas.

[0008] Therefore, an object of the present invention is to provide a fuel reforming system which improves the startability of the reformer, reduces the load on the battery and the like, and discharges clean exhaust gas immediately after starting.

[0009]

A first aspect of the present invention uses a reformer for accommodating a reforming catalyst to generate a reformed gas, and a reforming gas discharged from the reformer to generate a driving force. In a fuel reforming system configured to obtain a heat quantity necessary for a reforming reaction by providing a driving source for generation, and the reformer performing heat exchange with heat of exhaust gas discharged from the driving source, A startup reformer installed upstream of the reformer and supplied with fuel and air after being electrically heated at startup to generate a hydrogen-rich gas is provided.

In a second aspect based on the first aspect, the start-up reformer comprises a conductive material for electrically heating a catalyst which produces a hydrogen-rich gas.

In a third aspect based on the first aspect, the starting reformer is provided with a plus electrode and a minus electrode, a voltage is applied between the electrodes to generate plasma, and the plasma is activated by the energy of the plasma. A hydrogen-rich gas is produced from the fuel, water and air supplied to the reformer.

A fourth aspect of the present invention is the fuel cell system according to any one of the first to third aspects of the invention, wherein the amount of electricity supplied to the reformer for start-up and the amount of fuel and air supplied to the reformer for start-up depend on the temperature of the reformer for start-up. Controlled.

In a fifth aspect based on the fourth aspect, the supply amounts of fuel and air to the reformer and the starting reformer are controlled according to the temperature of the reformer.

[0014]

According to the first aspect of the invention, the fuel reforming system is provided with the reformer for generating the reformed gas by using the reforming catalyst, and the drive source for generating the driving force by using the reformed gas. ,
The reformer is configured to obtain the heat used for the reforming reaction by exchanging heat with the heat of the exhaust gas discharged from the drive source, and is installed upstream of the reformer, and at the time of start-up. A startup reformer was provided that was electrically heated and then fed with fuel and air to produce a hydrogen-rich gas.

When the reforming reaction carried out in the reformer is carried out using a hydrocarbon fuel, the reaction is roughly classified into a steam reforming reaction and a partial oxidation reaction. These reactions can be represented by the following chemical formulas:

The steam reforming reaction is

[0017]

[Equation 1] The partial oxidation reaction is an endothermic reaction represented by

[0018]

[Equation 2] The reaction becomes exothermic as shown by.

In any case, the following reactions are accompanied at the same time.

[0020]

[Equation 3]

[0021]

[Equation 4] Therefore, the composition of the reformed gas is a mixed gas containing H2, CO, and CH4 as main components.

At the time of startup, the startup reformer is first energized and heated, and the temperature of the reforming catalyst is raised to an activation temperature at which a stable reforming reaction occurs. The temperature of the start-up reformer further rises due to the heat generated during the reaction.

The reformed gas produced in the start-up reformer is a hydrogen-rich gas and is a high temperature gas. When this gas flows into the downstream reformer, the reforming catalyst of the reformer rises in temperature and reaches the activation temperature. At this time, by further supplying fuel, air, and steam to the reformer, the reforming reaction in the reformer shifts to the main reaction of the steam reforming reaction to generate reformed gas.

This reformed gas is supplied to a drive source, burned in an engine as a drive source, for example, and is used for power generation in the case of a fuel cell, and exhaust gas is discharged. The exhaust gas is sent to the reformer, and the reformer catalyst is heated by the heat of the exhaust gas in the reformer, and is maintained at an activation temperature suitable for the reforming reaction. The supply of fuel and air to the starting reformer is stopped at the time when the production of the reformed gas in the reformer can be maintained by heat exchange with the heat of the exhaust gas.

Therefore, by making the reformer at the time of startup and the reformer at the time of normal operation separate, the reformer at the time of startup is a high-temperature gas required for warming up the reformer for normal operation. The capacity of the reformer for start-up can be reduced, the power required for the start-up can be reduced, and the load on the battery can be suppressed. Also, by providing two reformers according to the application, the electric heating function does not become high when the electric heating function is not used, and the structure of each reformer can be simplified to improve serviceability. Can be improved. Furthermore, by immediately heating the reformer for start-up by electrical heating immediately after start-up to generate a high-temperature hydrogen-rich gas, exhaust gas in which harmful components are suppressed can be discharged immediately after start-up.

In the second aspect of the present invention, the start-up reformer is provided with the conductive material for electrically heating the catalyst that produces the hydrogen-rich gas, so that the start-up reformer is heated rapidly. ,
The warm-up can be completed in a short time, and the warm-up time of the system can be shortened.

In the third invention, the starting reformer is provided with a plus electrode and a minus electrode, a voltage is applied between the electrodes to generate plasma, and the plasma energy is used to reform the fuel. High-temperature hydrogen-rich gas can be generated in a short time, and the warm-up time of the system can be shortened.

In the fourth aspect of the present invention, the starting property of the starting reformer is controlled by controlling the amount of electricity supplied to the starting reformer and the amounts of fuel and air supplied to the starting reformer according to the temperature of the starting reformer. It is possible to suppress the load of the power supply source, for example, the battery, which accompanies the start-up without impairing the power supply.

In the fifth aspect of the invention, the partial oxidation reaction is minimized by controlling the amounts of fuel and air supplied to the reformer and the starting reformer according to the temperature of the reformer. Therefore, it is possible to minimize the efficiency decrease due to the partial oxidation reaction of the startup reformer.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of a fuel reforming system of the present invention will be described below with reference to the accompanying drawings. According to FIG.
This fuel reforming system is required for the main fuel reformer 1 that generates reformed gas during normal operation, and a part of the fuel of the main fuel reformer 1 at the time of start-up and that fuel to cause a partial oxidation reaction. Start-up reformer 2 that produces hydrogen-rich gas using air
A battery (or a condenser) 3 for supplying electric power to the starting reformer 2, a vaporizer 4 for supplying a fuel (for example, a hydrocarbon fuel), water and air to vaporize them, and a main fuel reformer. An engine 5 that discharges exhaust gas that serves as a heat source for the reforming reaction in the quality control device 1 and the vaporization in the vaporizer 4, and the starting reformer 2
And a compressor 6 for supplying air to the carburetor 4.

The start-up reformer 2 is constructed such that a reforming catalyst supporting plate in which a catalyst metal is supported on a conductive metal plate and a vaporized fuel and a fuel gas such as air are in contact with the surface of the reforming catalyst supporting plate. The reforming catalyst supporting plate is constituted by a passing fuel gas passage, and electric power from the battery 3 is supplied to the reforming catalyst supporting plate to heat the reforming catalyst supporting plate to cause a partial oxidation reaction. Further, the conductive metal plate and the catalyst may be separately provided.

As another structure of the starting reformer 2, the starting reformer 2 is provided with a plus electrode and a minus electrode, and a voltage is applied between the plus electrode and the minus electrode to generate plasma. Alternatively, the energy of plasma may be used to cause a partial oxidation reaction. In either configuration, the startup reformer can finish warming up in a short time, and the warming-up time as a system can be shortened.

The normal operation state of this system will be explained.
The fuel supplied from a fuel supply source (not shown) is supplied to the vaporizer 4, and the vaporizer 4 serves as water for the steam reforming reaction in the main fuel reformer 1 and also as an oxygen source for the partial oxidation reaction. The respective air is supplied from a supply source (not shown).

The carburetor 4 has a structure for exchanging heat with the high temperature exhaust gas discharged from the engine 5, and the supplied fuel, water and air are vaporized by using the heat of the exhaust gas as a heat source. .

The fuel, water vapor and air vaporized in the vaporizer 4 are supplied to the main fuel reformer 1, and a reforming reaction is generated by using the heat of the exhaust gas discharged from the engine as a heat source to produce reformed gas. .

The reformed gas is supplied to the engine 5, mixed with the air supplied from the air cleaner 7, and burned. In this system, the engine 5 is operated by the reformed gas, high-temperature exhaust gas is discharged, and the heat of this exhaust gas is
As described above, it is used as a heat source for the reforming reaction of the main fuel reformer 1 and the vaporization of the vaporizer 4.

The engine is not warmed up sufficiently and the heat quantity of the exhaust gas does not satisfy the reforming reaction (steam reforming reaction which is an endothermic reaction). For example, at start-up, the main fuel reformer 1 and the vaporizer 4 are The starting reformer 2 connected to the flow path branched from the intervening flow path is started. After the temperature of the starting reformer 2 is raised by the electric power from the battery 3, the starting reformer 2 is supplied with fuel and air to cause a partial oxidation reaction which is an exothermic reaction.

The operating state of each component at startup will be described with reference to the timing chart of FIG. 2 and the flowchart of FIG.

First, in step S1 of FIG. 3, the reformer 2 for start-up is used.
Power supply to the device is started (time t1 in FIG. 2). Therefore, the temperature of the start-up reformer 2 rises rapidly, and the warm-up of the start-up reformer is completed in a short time. Next, it is determined whether or not the temperature exceeds the predetermined temperature Ts0 (step S2). When the temperature of the startup reformer 2 exceeds a predetermined temperature Ts0 (time t
2) Supplying fuel and air for partial oxidation reaction to the start-up reformer 2 (step S3). Therefore, due to the heat generated by the partial oxidation reaction in the starting reformer 2, the starting reformer 2
Will heat up faster. The hydrogen-rich gas generated by the start-up reformer 2 is supplied to the main fuel reformer 1, and the main fuel reformer 1 is heated.

The fuel (hydrogen-rich gas) from the starting reformer 2 to the main fuel reformer 1 is supplied to the engine, mixed with air and burned in the engine 5, and the engine 5 is started (step S4), the temperature of the engine 5 rises. Moreover, the temperature of the exhaust gas also begins to rise.

Next, it is determined whether or not the temperature of the startup reformer 2 exceeds a predetermined temperature Ts1 (step S).
5). When it exceeds, the power supply to the starting reformer 2 is stopped (time t3, step S6). In this way, by controlling the energization state and the supply state of fuel and air according to the temperature of the start-up reformer 2, electric power is supplied to the start-up reformer without impairing the startability of the start-up reformer. The load on the battery to be supplied can be reduced.

Next, in step S7, it is judged whether or not the temperature of the main fuel reformer 1 exceeds a predetermined temperature Ts2 suitable for the reforming reaction. When the temperature exceeds the predetermined temperature Ts2, the process proceeds to step S8, and the supply of fuel and air to the starting reformer 2 is stopped (stops from time t4 to t5). Therefore, by controlling the supply of fuel and air to the starting reformer 2 according to the temperature of the main fuel reformer 1, the partial oxidation reaction in the starting reformer 2 can be minimized. Therefore, it is possible to minimize the decrease in efficiency due to the partial oxidation reaction.

In step S9, the amounts of fuel, air and steam from the vaporizer 4 are controlled according to the temperature of the main fuel reformer 1.

That is, the temperature of the main fuel reformer is the predetermined temperature T.
The amount of fuel supplied to the starting reformer 2 stopped in the main fuel reformer 1 so as to be maintained at s2 and the air for partially oxidizing the increased amount of fuel are supplied through the vaporizer 4. (It gradually increases from time t4 to t5). At this time, the vaporizer 4 has not reached the temperature required for vaporizing the fuel, but the air sent to the vaporizer 4 is pressurized by the compressor 6 and is at a high temperature, and the gas from the starting reformer 2 is Is high temperature, the fuel and air vaporized by the vaporizer 4 by these heats are supplied to the main fuel reformer 1. When the vaporizer 4 reaches a predetermined temperature required for vaporization (time t4 ′), supply of steam from the vaporizer 4 to the main fuel reformer 1 is started. As the steam supply amount to the main fuel reformer 1 gradually increases, the main fuel reformer 1
The amount of air supplied to is decreased, and the supply of air is stopped when the amount of water vapor reaches a predetermined amount (time t6).

As described above, since the hydrogen-rich gas at the time of starting is generated by using the starting reformer 2 used only at the time of starting, the capacity of the starting reformer 2 is the main fuel reformer. It suffices if the capacity of the reformer for start-up is small, as long as it has a capacity to generate the high-temperature gas necessary for warming up the starter reformer 2, and the battery 3 that supplies power when the reformer for start-up 2 is started The load on the battery 3 can be suppressed, the battery 3 can be downsized, and the system can be downsized and lightened. Further, even if the reformer fails as in the prior art, the main fuel reformer 1 and the startup reformer 2 are configured to have different functions, and therefore even if a failure occurs, the respective components can be repaired. It suffices to exchange them, and service costs can be suppressed.

Further, since the reformer having a small capacity is used, its starting time is shorter than that of the prior art reformer, and the starting time of the system can be shortened.

Furthermore, since the hydrogen-rich gas can be supplied from the starting reformer 2 to the engine 5 via the main fuel reformer 1 immediately after the system is started, the exhaust gas discharged from the engine immediately after the engine is started is clean. It can be a natural exhaust gas.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a fuel reforming system for explaining the present invention.

FIG. 2 is a timing chart diagram similarly illustrating an operating state of each component.

FIG. 3 is a flow chart diagram for explaining the same control contents.

FIG. 4 is a schematic diagram of a conventional fuel reforming system.

[Explanation of symbols]

1 Main fuel reformer 2 Start-up reformer 3 battery 4 vaporizer 5 engine 6 compressor 7 Air cleaner

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuhiko Ishiwata             2 Takaracho, Kanagawa-ku, Yokosuka City, Kanagawa Prefecture             Sansan Co., Ltd. (72) Inventor Noboru Yamauchi             2 Takaracho, Kanagawa-ku, Yokosuka City, Kanagawa Prefecture             Sansan Co., Ltd. F-term (reference) 4G040 EA03 EA06 EB03 EB12 EB18                       EB31 EB42 EB43 EB44                 5H027 AA02 BA09 DD03 KK42 MM12

Claims (5)

[Claims] 1. A reformer for accommodating a reforming catalyst to generate a reformed gas, and a drive source for generating a driving force using the reformed gas discharged from the reformer. The reformer is installed upstream of the reformer in a fuel reforming system configured to exchange heat with the exhaust gas discharged from the drive source to obtain the amount of heat required for the reforming reaction. A fuel reforming system comprising a starting reformer for generating hydrogen-rich gas by being supplied with fuel and air after being electrically heated at startup. 2. The fuel reforming system according to claim 1, wherein the start-up reformer includes a conductive material for electrically heating a catalyst that generates a hydrogen-rich gas. . 3. The starting reformer is provided with a plus electrode and a minus electrode, a voltage is applied between the electrodes to generate plasma, and the energy of the plasma is used to supply the fuel supplied to the starting reformer. The fuel reforming system according to claim 1, wherein hydrogen-rich gas is produced from water and air. 4. The energization amount and the fuel and air supply amounts to the start-up reformer are controlled according to the temperature of the start-up reformer. The fuel reforming system described in 1. 5. The fuel reformer according to claim 4, wherein the amounts of fuel and air supplied to the reformer and the starting reformer are controlled according to the temperature of the reformer. system.