JP2003068346A - Reformer of fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reformer capable of less loading on a fuel cell at the start and shortening the start time. SOLUTION: In the reformer of the fuel cell provided with an evaporator 3 for evaporating the material, a catalytic burner 4 for heating the evaporator, a reformer 1 for generating a reformed gas including hydrogen to react fuel vapor from the evaporator and air, and a start burner 5 for supplying high temperature material vapor to the reformer at the start, it supplies air heated to a high temperature by introducing air into the heat exchanger at the start to a vapor pipe 13 downstream and the reformer, and provides the material to the evaporator after the vapor pipe and the reformer are heated to a high temperature, providing heat exchangers (3, 15) for heating air by a heat source of the catalytic burner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a reformer for supplying a reformed gas containing hydrogen as a main component to a fuel cell.

[0002]

2. Description of the Related Art In a fuel cell vehicle equipped with a fuel reformer, a power source that compensates for such reasons as a long start-up time of the fuel reformer and a slow follow-up to a load change. Many are equipped with a secondary battery. However, since mounting the secondary battery is disadvantageous in terms of vehicle weight and cost, it is desirable to make the secondary battery as small as possible. For this purpose, the reformer start-up time is shortened to reduce the power consumption required for start-up,
Alternatively, it is necessary to devise such as promptly supplying an appropriate raw material vapor to the reformer.

On the other hand, in Japanese Patent Laid-Open No. 2000-12060, at the time of start-up, the outlet portion of the air blower is throttled to increase the pressure ratio, and a circulation passage for connecting the discharge passage and the suction passage of the air blower is provided. It is disclosed that the discharge air temperature of an air compressor is controlled to a high temperature, and a switching valve is used to flow high temperature air directly to a reformer to promote a rise in the temperature of the reformer. Further, in Japanese Patent Laid-Open No. 5-290865, the air sent from the air blower is used to recover the heat of the combustion exhaust gas discharged from the combustion section of the reformer and the air exhaust gas discharged from the air electrode of the fuel cell. It has been proposed to preheat and supply it to a reformer or a fuel cell. In addition, for the sake of convenience of the following description, it is referred to as "warming up" to raise the temperature of the reformer or the CO removing device in the vicinity thereof to an operable temperature.
Shall be called.

However, in the former case, in which the high temperature air is generated by the air blower and the reformer is warmed up, power consumption is large at the time of start-up and the capacity of the secondary battery needs to be increased. There are problems with application to fuel cell vehicles. Further, in the latter configuration in which the air supplied to the combustion section of the reformer is warmed up by the heat of the combustion exhaust gas of the reformer, it is possible to recover the heat and reduce the raw material, but the temperature of the combustion section is Since the reformer is indirectly warmed up in the combustion section without any change, quick startup is difficult. In addition, at the time of start-up, even if raw material steam starts to be generated in the evaporator, the steam pipe is cold and the fuel vapor is condensed again, which causes an unstable supply of steam to the reformer and a longer start-up time. .

The present invention has been made in view of these conventional problems, and an object thereof is to provide a reformer capable of downsizing the secondary battery and shortening the starting time.

[0006]

According to a first aspect of the invention, an evaporator for vaporizing a raw material, a catalytic combustor for heating the evaporator, and a raw material vapor from the evaporator are reacted with air to generate hydrogen. A fuel cell including a reformer for generating a reformed gas containing the CO, a CO remover provided downstream of the reformer, and a startup combustor for supplying high-temperature raw material vapor to the reformer at startup. In the reformer, a heat exchanger for heating air by using the catalytic combustor as a heat source is provided, and at the time of start-up, the temperature of the air introduced into the heat exchanger is increased and the temperature of the air is increased by the steam pipe and the reformer on the downstream side of the evaporator. A start-up control means for supplying the raw material to the evaporator was provided after supplying the raw material to the quality device and raising the temperature of the steam pipe and the reformer.

According to a second aspect of the present invention, the start control means includes a first air introduction passage for introducing air from the air blower supplied to the start combustor and the reformer into the heat exchanger, and a CO remover. A reforming gas passage communicating with the fuel cell stack is provided with a second air introducing passage communicating with the catalytic combustor, and a valve opening / closing each of the air introducing passages. The air was supplied to the heat exchanger, the reformer, and the catalytic combustor.

A third invention is the start control means of the second invention, wherein the air from the heat exchanger is introduced into a CO remover for removing carbon monoxide in the reformed gas from the reformer. No. 3 air introduction passage and valve means for opening this air introduction passage at the time of starting.

According to a fourth aspect of the present invention, in each of the above aspects, the heat exchanger also serves as the evaporator.

A fifth invention is the same as the first invention,
The steam pipe had a double pipe structure, and the exhaust gas from the evaporator was introduced into the outer passage portion.

According to a sixth aspect of the present invention, the start control means of the first aspect includes pipe temperature detecting means for detecting the temperature of the steam pipe and gas temperature detecting means for detecting the outlet gas temperature from the heat exchanger. The raw material is supplied to the evaporator after the pipe temperature and the gas temperature exceed the respective specified values.

[0012]

According to the first aspect of the present invention, air is supplied to the heat exchanger before the raw material (hydrocarbon-based fuel such as methanol or gasoline or a mixed fuel of the same and water) is supplied to the evaporator at startup. Since the air introduced to the steam pipe and the reformer is heated by exchanging heat with the combustion gas from the catalytic fuel unit, the raw material vapor generated when the raw material is fed into the evaporator thereafter. Can be introduced into the reformer without being condensed, and the reaction of the reformer can be stably and promptly performed. Since a large amount of power is not required to introduce air into the steam pipe and the reformer, the capacity of the secondary battery for that purpose can be small.

Further, by introducing the preheated air at the time of start-up and introducing the raw material into the evaporator, it is possible to reduce the internal stress change of the evaporator at the start of the introduction of the raw material and to expect the effect of extending the life of the evaporator. Furthermore, if the starting combustor is ignited during low-load operation, the raw material of the evaporator is shut off, and air is introduced to perform idle operation, the raw material vapor will condense in the steam pipe when the operation shifts to high-load operation again. It is also possible to prevent this from occurring and to reduce the amount of raw material supply during idling.

According to the second aspect of the present invention, an air blower for supplying combustion air or reforming air to the starting combustor and the reformer can be used as a means for introducing air into the heat exchanger. It is possible to promote warm-up of the steam pipe, the reformer and the like without complicating the configuration of the above.

According to the third aspect of the invention, since the CO remover is warmed up by the heated air from the heat exchanger described above,
In the fuel cell device equipped with the CO remover, the carbon monoxide selective catalyst can be quickly brought to the activation temperature.

According to the fourth aspect of the present invention, the heat exchanger and the evaporator are used together, so that the structure of the apparatus can be simplified.

According to the fifth aspect of the present invention, warming up of the steam pipe can be further promoted, and the reformer can be warmed up more efficiently, or the reaction can be performed with good response.

According to the sixth aspect of the invention, it is possible to more accurately supply the fuel vapor to the reformer by feeding the raw material into the evaporator at an appropriate timing.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of the first embodiment. In the figure, 1 is a reformer for producing a reformed gas containing hydrogen as a main component from raw material vapor and air, and 2 is CO removal for removing carbon monoxide in the reformed gas by a partial oxidation reaction by a CO removal catalyst. A reactor 3, a vaporizer 3 for vaporizing a liquid raw material by heat exchange, a catalyst combustor 4 for generating a combustion gas serving as a heat source of the evaporator 3 by a catalytic reaction, and a reformer 5 for reforming a high-temperature starting gas at startup. A start-up combustor to be supplied to the reformer 1, 6 is an air blower for supplying air required for combustion and reforming reaction to the reformer 1 and the combustors 4 and 5 via the air supply passage P0 under pressure, and 7 is It is a fuel cell stack that reacts the reformed gas generated by the reformer 1 with air to generate electricity.

Reference numeral 8 denotes a reformed gas passage Pr from the CO remover 2.
With a three-way valve structure for selectively communicating the fuel cell stack 7 or the air introduction passage (corresponding to the second air introduction passage of the present invention) P2 to the catalytic combustor 4 with a three-way valve structure, and 9 an air supply passage An air control valve for switching supply or stop of P0 pressurized air to the reformer 1, 10 is also an air control valve for switching supply or stop of P0 pressurized air to the CO remover 2, and 11 is also P0. It is an air control valve that switches between supplying and stopping pressurized air to the catalytic combustor 4. Reference numeral 12 is an air control valve for supplying the compressed air in the air supply passage P0 to the starting combustor 5 at the time of starting. Reference numeral 13 is a steam pipe through which warm-up heating air or raw material steam from the evaporator 3 is introduced, and reference numeral 14 is an air introduction passage that branches from the air supply passage P0 and supplies pressurized air to the evaporator 3 (the first embodiment of the present invention. 1 is an air control valve that opens and closes P1.

Reference numerals 19 to 22 are temperature detectors, 19 is the outlet gas temperature of the evaporator 3, and 20 is the evaporation pipe P4.
Of the reformer 1, for example, the reformer temperature at a position of about 1/4 from the upstream end of the reformer 1, and 22 the reformed gas temperature at the outlet of the CO remover 2. Based on these temperature detection results, a start-up control means (not shown) controls the opening and closing of the above-mentioned valves to perform start-up control so that the reformer and the fuel cell are started in a minimum start-up time.

Next, the control routine executed by the microcomputer constituting the start-up control means will be described with reference to the flow chart shown in FIG. This process is repeatedly executed periodically. It should be noted that in the following description and flow charts, the numbers indicated with the reference symbol S represent processing step numbers.

In this startup control, the reformed gas switching valve 8 is first switched to the catalytic combustor 4 side, and then the air blower 6 is started (S1 and S2). At this point, the reformer 1
The air control valve 9 to the CO and the air control valve 10 to the CO remover 2 are closed. Next, the air control valve 11 is opened to introduce air into the catalytic combustor 4, and fuel such as methanol is injected to ignite the catalytic combustor, and the combustion gas heats the evaporator 3 (S3). Further, the air control valve 14 is opened to introduce the pressurized air from the air blower 6 into the evaporator 3 (S4). On the other hand, the air control valve 12 is opened and the starting combustor 5 is burned in a fuel rich state with the raw material to generate high temperature fuel vapor (S5). Further, the air control valve 10 is opened to introduce air into the CO remover 2 (S6). After that, wait until the temperature detected by the temperature detector 20 attached to the steam pipe 13 reaches a specified value that serves as a criterion for determining the warm-up state of the steam pipe, and when the temperature reaches the specified value, attach it to the outlet of the evaporator 3 next. It waits until the gas temperature detected by the temperature detector 19 reaches a specified value which is a criterion for warming up the evaporator (S7 to S8).

In this way, after confirming that the steam pipe 13 and the evaporator 3 have been warmed up, the process for producing the reformed gas is started. That is, while the air control valve 14 is closed and a required amount of raw material is supplied to the evaporator 3, the air control valve 9 is opened to introduce the reforming air into the reformer 1 (S9 to S11). After that, the process waits until the temperature detected by the temperature detector 21 attached to the reformer 1 reaches a specified value corresponding to the warm-up completion temperature of the reformer (S12). When it is determined that the warm-up of the reformer 1 is completed, the air control valve 12 is closed and the fuel injection is stopped to end the generation of combustion gas by the start-up combustor 5 (S13). Next, after waiting for the temperature detected by the temperature detector 22 attached to the outlet of the CO remover 2 to reach the specified value corresponding to the warm-up determination standard of the CO remover, the reformed gas switching valve 8 is set to the fuel cell stack 7. Switch to the side and complete the startup process (S
14-S15). After that, the reformed gas from the reformer 1 and the CO remover 2 is supplied to the fuel cell stack 7. As for the temperature detector 22, instead of this, a CO concentration detector may be applied, and it may be determined that the warm-up is completed when the detected CO concentration reaches a specified value, for example, 40 ppm or less.

Next, another embodiment of the present invention shown in FIG. Portions corresponding to those in FIG. 1 are assigned the same reference numerals and explanations thereof will be omitted, and only different portions will be explained. FIG. 3 shows a second embodiment. In this embodiment, a heat exchanger 15 that supplies heated air for warming up the CO remover 2 is provided between the catalytic combustor 4 and the evaporator 3, and pressurized air from the air blower 6 is provided at the time of startup. Is introduced into the heat exchanger 15 by opening the air control valve 16, and the air heated by heat exchange with the combustion gas from the catalytic combustor 4 is introduced into the air introduction passage P3.
The CO 2 is preferentially supplied to the CO remover 2 via (corresponding to the third air introduction passage of the present invention).

FIG. 4 shows a third embodiment of the present invention. In this embodiment, an air control valve 17 having a three-way valve structure is provided in the middle of the steam pipe 13, and heating air for warming up, which is supplied from the evaporator 3 at the time of startup, is supplied from the steam pipe 13 to the reformer 1 or the air introduction passage. This is different from the first embodiment in that the CO remover 2 can be selectively supplied or distributed via P3. After the warming up of the CO remover 2 is completed, the air control valve 17 is switched to connect the steam pipe 13 to only the reformer 1, and thereafter, heated air or raw material steam is supplied to the reformer 1. To do.

FIG. 5 shows a fourth embodiment of the present invention. In this embodiment, in addition to the configuration of the first embodiment, the outer passage portion 18 surrounds the steam pipe 13 so as to surround it.
Is formed to have a double pipe structure, and a structure for introducing exhaust gas from the evaporator 3 into the outer passage portion 18 is added. Since the steam pipe 13 can be warmed up faster by introducing the exhaust gas into the outer passage portion 18, and the outer passage portion 18 has a heat retaining effect even after the warming up, the fuel is prevented from condensing at a low load. The effect of doing can be expected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart showing the contents of activation control according to the first embodiment.

FIG. 3 is a schematic configuration diagram of a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a fourth embodiment of the present invention.

[Explanation of symbols]

1 reformer 2 CO remover 3 evaporator 4 catalytic combustor 5 Combustor for startup 6 air blower 7 Fuel cell stack 8,9,10,11,12,14 Air control valve 13 Steam piping 19,20,21,22 Temperature detector P1, P2, P3 Air introduction passage

Claims (6)

[Claims] 1. An evaporator for vaporizing a raw material, a catalytic combustor for heating the evaporator, and a reformer for reacting raw material vapor from the evaporator with air to produce a reformed gas containing hydrogen. And a CO remover provided downstream of the reformer, and a start-up combustor for supplying high-temperature raw material steam to the reformer at the time of start-up. A heat exchanger that heats the air by using the heat source as a heat source is provided, and at the time of start-up, air is introduced into the heat exchanger to raise the temperature of the air and supply it to the steam pipe and reformer on the downstream side of the evaporator. A reforming device for a fuel cell, characterized in that start-up control means for supplying a raw material to an evaporator is provided after raising the temperature of the pledget. 2. The start control means includes a first air introduction passage for introducing air from an air blower supplied to a start combustor and a reformer into a heat exchanger, a CO remover and a fuel cell stack. A second air introduction passage that communicates a reformed gas passage that communicates with the catalyst combustor and a valve that opens and closes each of the air introduction passages, and at the time of start-up, the valve is opened to exchange heat from the air blower. The fuel cell reformer according to claim 1, wherein the reformer is configured to supply the reformer, the reformer, and the catalytic combustor. 3. The start control means comprises a third air introduction passage for introducing air from the heat exchanger into the CO remover, and a valve means for opening the air introduction passage at the time of starting. Fuel cell reformer. 4. The reformer for a fuel cell according to claim 1, wherein the heat exchanger also serves as the evaporator. 5. A double pipe structure having an outer passage portion through which the exhaust gas from the evaporator is introduced in the steam pipe.
A reformer for a fuel cell according to 1. 6. The start-up control means includes a pipe temperature detection means for detecting the temperature of the steam pipe and a gas temperature detection means for detecting the exhaust gas temperature from the heat exchanger, and the pipe temperature and the gas temperature are different from each other. The reformer for a fuel cell according to claim 1, wherein the reformer is configured to supply the raw material to the evaporator after exceeding the specified value.