JPH02170364A - Method of stopping fuel battery with methanol modifier - Google Patents

Abstract

PURPOSE:To suppress hydrogen release to the outside and enhance the safety by actuating the methanol supply system for burner combustion of a methanol modifying device at the same time as stop of power generation in a fuel battery, and by performing mixed combustion of the methanol with unreacted hydrogen in the fuel battery. CONSTITUTION:At the time of stopping the drive of a fuel battery 2, a controller 36 stops operation of a water pump 7 and a methanol pump 10 and opens a load contactor 41. Then another methanol pump 20 is driven to make mixed combustion of methanol with unreacted hydrogen in the fuel battery 2 with the aid of air given by a blower 19, to cause consumption of hydrogen generated from the fuel battery 2. This combusting operation is continued till complete consumption of the uncombusted hydrogen, and then drive of the methanol pump 20 is stopped. This suppresses hydrogen release to the outside when the drive is stopped, which allows ensuring the safety.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for stopping the operation of a fuel cell equipped with a methanol reformer.

[Prior Art] 'There has conventionally been a fuel cell that generates electricity using hydrogen and oxygen, and there is a method of obtaining this hydrogen through a methanol reforming reaction. In this methanol reformer,
Using methanol supplied by a methanol pump and water supplied by a water pump as raw materials, hydrogen and carbon dioxide are generated under a Cu-Zn catalyst, supplying hydrogen to the fuel cell, and removing unreacted hydrogen in the fuel cell. There is a method of refluxing and burning the unreacted hydrogen in a burner to obtain the heat necessary for the methanol reforming reaction.

[Problem to be Solved by the Invention] However, when stopping the power generation of the fuel cell, the water pump and methanol pump to the methanol reformer are stopped, but the catalyst layer or reformer of the methanol reformer is If unreacted raw materials remain in the raw material supply system, a reforming reaction occurs due to residual heat even after the pump is stopped, and hydrogen is generated. Since the hydrogen is supplied to the burner of the methanol reformer via the fuel cell, there is a problem in that once the hydrogen flame in the burner is extinguished, the hydrogen is released to the outside.

An object of the present invention is to provide a method for stopping the operation of a fuel FI cell equipped with a methanol reformer that suppresses the release of hydrogen to the outside when the fuel cell is stopped and has excellent safety.

[Means for Solving the Problems] The present invention includes a fuel cell that generates electricity using hydrogen and oxygen, and a burner that burns methanol or hydrogen and supplies the heat necessary for the methanol reforming reaction. In a fuel cell equipped with a methanol reformer that performs a methanol reforming reaction under a catalyst using methanol as a raw material to generate hydrogen and carbon dioxide, at the same time as the power generation of the fuel cell is stopped, a methanol supply system for combustion of the burner is provided. The gist of this invention is a method for stopping the operation of a fuel cell equipped with a methanol reformer that operates to burn methanol and unreacted hydrogen from the fuel cell and consume the unreacted hydrogen from the fuel cell. It is something to do.

[Action 1: Power generation of fuel cell] At 115, the methanol supply system for burner combustion of the methanol reformer is operated to mix and burn methanol and unreacted hydrogen in the fuel cell. As a result, unreacted hydrogen from the fuel cell is consumed, and hydrogen cannot be released to the outside.

[Embodiment] An embodiment in which the present invention is embodied in a fuel cell mounted on a vehicle will be described below with reference to the drawings.

FIG. 1 shows the power supply system of the traveling motor of this embodiment, which includes a methanol reformer 1, a combustion battery 2, and a DC/DC power supply system as a whole.
It is composed of a DC converter 3, a lead acid battery 4, and a running DC motor 5.

The water in the water tank 6 is supplied to the mixer 8 by driving the water pump 7, and the methanol in the methanol tank 9 is supplied to the mixer 8 by driving the methanol pump 10. In this mixer 8, water and methanol are mixed. The mixed raw materials are supplied to the methanol reformer 1 as reforming raw materials.

The methanol reformer 1 has a cylindrical frame 1, as shown in FIG. 2 and FIG.
1, a heat insulating material 12 is arranged. That frame 11
A plurality of catalyst layers 13 are arranged concentrically in the interior, and a reforming catalyst 14 is filled in the contact layer 13. As the reforming catalyst 14, a cuo or zno type catalyst is used.

Further, the reforming raw material of methanol/water mixed in the mixer 8 is supplied into the frame 11 of the methanol reformer 1 via the reforming raw material supply pipe 15, and the reforming raw material supply pipe 15 is spirally extended in the center of the room 11, and is roughly connected from the branch part 16 to the bottom of each contact layer 13.The upper end of each reaction tube 13 is collected and hydrogen is It communicates with the outside through a discharge pipe 17.

A burner 18 is provided in the upper part of the inner cylinder of the frame 11, to which air (oxygen) is supplied by a blower 19 and methanol is supplied from the methanol tank 9 by a methanol pump 20. When the temperature rises at the time of startup of the methanol reformer 1, methanol is combusted with oxygen in the air by the burner 18, and the high temperature combustion gas passes through the inner cylinder and enters the reforming raw material supply pipe 15. The methanol/water reforming raw material is heated, passes through the outer cylinder, heats each catalyst layer 13, and is discharged to the outside from the exhaust passage 21.

Roughly speaking, unreacted hydrogen from the fuel cell 2 is supplied to the burner 18, and after the temperature of the methanol reformer 1 has finished rising, this aqueous system is combusted by the oxygen in the air supplied by the blower 19. The high-temperature combustion gas overheats the reforming material supply pipe 15 and heats the catalyst layer 13. That is, when the temperature of the methanol reformer 1 is raised, the catalyst layer is heated with a methanol flame, and once the reaction temperature of about 320° C. is reached and the methanol reforming reaction is performed, the methanol flame is stopped. The hydrogen flame generated by unreacted hydrogen from the fuel cell 2 is switched to supply the heat necessary for the reforming reaction.

Then, the combustion gas passes from the inner cylinder of the methanol reformer 1 to the outer cylinder, and is discharged to the outside from the exhaust passage 21.

In addition, in the catalyst layer 13, i! due to combustion in the burner 8 mentioned above is generated. Hydrogen is produced in the reforming catalyst 14 using methanol and water as raw materials in an am atmosphere (CHOH
+H20→3H2+CO2-ΔQ). This hydrogen production reaction is an endothermic reaction and therefore requires heating.

In the fuel cell 2, a hydrogen electrode 23 and an oxygen electrode 24 are disposed facing each other with a phosphoric acid electrolyte 22 in between, and hydrogen generated by the methanol reformer 1 is passed from the hydrogen discharge pipe 17 to the filter 25 on the hydrogen electrode 23 side. Supplied via Further, air (oxygen) is supplied to the oxygen electrode 24 side by a blower 26.

Furthermore, a heat exchanger (oil pipe) 27 for heating and cooling the fuel cell 2 is arranged in the fuel FI cell 2,
A heat exchanger 2 is installed inside this pipe by driving an oil pump 28.
Oil is circulated through 9 and an oil tank 30.

The heat exchanger 29 is provided with a starting burner 31, to which methanol is supplied from the methanol tank 9 by a methanol pump 32 and air is supplied by a blower 33. When starting up the fuel cell 2, methanol is burned in the starting burner 31 to heat the oil, the oil is circulated, and the temperature of the fuel cell 2 is raised to around 100°C.

When the temperature of the fuel cell 2 reaches approximately 100° C., power generation begins. When the fuel cell 2 starts generating electricity, the temperature rises due to an exothermic reaction, but the appropriate temperature for the reaction is around 190° C.±20° C., and it is necessary to control the temperature within that temperature range.

The fuel cell 2 is cooled by driving the blower 33 and the heat exchanger 29.
This is done by cooling the circulating oil. Also, the temperature of the fuel cell 2 is raised by the methanol pump 32 and the blower 3.
3 and ignites a methanol flame with the starting burner 31 to heat the circulating oil in the heat exchanger 29.

Further, in the fuel cell 2, an electromotive force is generated between the hydrogen electrode 23 and the oxygen electrode 24 due to the hydrogen supplied from the methanol reformer 1 and the air (oxygen) supplied by the pro 926. Further, unreacted hydrogen is returned to the burner 18 of the methanol reformer 1 via the flashback preventer 34.

The picture electrode of the fuel cell 2 is connected to a DC/DC converter 3. Further, a vehicle travel motor 5 is connected between the output terminals of the DC/DC converter 3 via a lead acid battery 4 . The travel motor 5 has switching contactors (for forward and reverse > 35a, 35b connected in parallel, and a transistor Tr connected in series to the travel motor 5.Furthermore, a flywheel is connected to the connection points a and b. Diode D1
゜D2 is connected. Then, with either switching contactor 35a or 35b closed, the transistor T
The rotational speed of the travel motor 5 is controlled by carrying out chopper control of r.

A controller 36 that controls the entire system includes each of the blowers 19, 26.33 and pumps 7.10°20.28.3.
At the same time, a signal from a temperature sensor 37 that detects the catalyst temperature of the methanol reformer 1 and a signal from a temperature sensor 38 that detects the temperature of the fuel cell 2 are inputted to detect each temperature. Further, the controller 36 detects the output voltage VrC of the fuel cell 2 by the voltage detection section 39, and detects the terminal voltage VrC of the lead-acid battery 4 by the voltage detection section 40.
Detect B. Roughly speaking, the controller 36 detects the charging/discharging current 8 of the lead acid battery 4 by the current sensor 42, and also detects the temperature of the lead acid battery 4 by the temperature sensor 43.

The controller 36 outputs the output current command value from the fuel cell 2 to the DC/DC converter 3, and also outputs the output current command value from the fuel cell 2 to the DC/DC converter 3.
The load contactor 41 provided between the C converter 3 and the lead acid battery 4 is controlled to open and close.

Next, the startup control of this system will be explained.

First, the controller 36 drives the methanol pump 20 and the blower 19 until the catalyst temperature of the methanol reforming installation 1 reaches the lowest temperature (approximately 250° C.) at which the reforming reaction can occur, so that the methanol is combusted by the burner 18 and the catalyst The temperature of layer 13 is increased. At the same time, the controller 36 drives the methanol pump 32 and the blower 33 until the fuel cell 2 reaches the minimum temperature (approximately 100°C) at which it can generate electricity, and the starting burner 3
1, the metal is combusted, and the oil is circulated by the oil pump 2B to raise the temperature of the fuel cell 2.

When the controller 1 to the roller 36 reach the lowest temperature (approximately 250°C) at which the methanol reformer 1 can undergo a reforming reaction and the lowest temperature at which the fuel cell 2 can generate electricity (approximately 100°C), the water pump 7 and drives the methanol pump 10,
Supply of the reforming raw material to the methanol reformer 1 is started. Then, the hydrogen reformed by the reforming catalyst 1514 of the methanol reformer @1 is supplied to the fuel cell 2 via the filter 25.

At this time, unreacted hydrogen from the fuel cell is combusted in the part 18 of the methanol reformer 1 via the flashback preventer 34.

After that, the controller 36 controls the methanol pump 20! of the methanol reformer 1! The operation is stopped and the burner 18 in the methanol reformer 1 is caused to mainly burn unreacted hydrogen.

The controller 36 drives the processor 926 to supply air (oxygen) at the same time as hydrogen supply to the fuel cell 2 begins. When the supply of hydrogen and oxygen begins, an open voltage is generated between both electrodes of the fuel cell 2. After the open circuit voltage reaches a specified voltage, the controller 36 closes the load contactor 41 and starts supplying power to the outside. At this time, the controller 36 outputs the output current command value from the fuel cell 2 to the DC/DC converter 3, and the DC/DC converter 3 performs constant current output control in multiple stages according to that value. . Roughly speaking, the controller 36 constantly detects the terminal voltage VB, charging/discharging current IB, and temperature of the lead-acid battery 4.
It shows the state of charge of the battery. The output current command value to the DC/DC converter 3 is output in correlation with the state of charge of the lead acid battery 4. That is, when the discharge of the lead-acid battery/battery 4 is progressing, the output of the fuel cell 2 is set to the maximum side,
When the lead acid battery 4 is sufficiently charged, the output is set to the low output side. The controller 36 causes the starting blower 33 to start the fuel cell 2 at the same time that the fuel cell 2 starts generating electricity.
to cool down.

Next, a method of operating the fuel cell 2 and lead acid battery 4 will be explained.

The output power of the fuel cell 2 is supplied via a DC/DC converter 3 to a load such as a travel motor 5 or to a lead acid battery 4 as an auxiliary battery.
The C converter 3 controls its output so that it always becomes the charging voltage VB of the lead-acid battery 4, and performs a hybrid operation using the fuel cell 2 and the lead-acid battery 4. Also, methanol reformer 1゜fuel cell 2. The output of the DC/DC converter 3 is controlled to be at the maximum level when the lead-acid battery 4 is being discharged, and to become lower as the battery becomes fully charged.

Roughly speaking, when the drive of the fuel cell 2 is stopped, the controller 1 to the roller 36 stop driving the water pump 7 and the methanol pump 10, and open the load contactor 41. moreover,
The controller 36 drives the methanol pump 20 to mix and burn methanol and unreacted hydrogen in the fuel cell 2 with air (acid radicals) by the blower 19, causing the hydrogen generated from the fuel cell 2 to be consumed. Unreacted raw materials remain in the reforming catalyst 14 or the reforming raw material supply system of the methanol reformer 74 apparatus 1, and even after the drive is stopped, reforming occurs due to residual heat, etc., and hydrogen is generated intermittently. By continuously burning the methanol flame in this state, even if the hydrogen flame becomes intermittent, the hydrogen flame will not go out and hydrogen will not be released to the outside.

Then, when the fuel cell 2 stops generating power, the controller 1 to the roller 36 perform the combustion operation of the methanol driven by the methanol pump 20 and the unreacted hydrogen from the fuel cell 2 until the unreacted hydrogen is completely consumed. After 14 minutes, driving of the methanol pump 20 is stopped.

According to this embodiment, when the fuel cell 2 stops generating electricity, the combustion methanol supply system (methanol pump 20) of the burner 18 of the methanol reformer 1 is operated to remove methanol and the unused fuel in the fuel cell 2. The hydrogen is burned simultaneously with the reacted hydrogen, so that the unreacted hydrogen from the fuel cell 2 is not consumed.Therefore, when the fuel cell 2 is stopped, the release of hydrogen to the outside is suppressed, resulting in excellent safety. can do.

[Effects of the Invention] As detailed above, according to the present invention, the excellent effect of suppressing the release of hydrogen to the outside when the fuel cell is stopped and ensuring safety is exhibited.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a fuel cell according to an embodiment, FIG. 2 is a sectional view of a methanol reformer, and FIG. 3 is a sectional view taken along line AA in FIG. 1 is a methanol reformer, 2 is a fuel cell, 18 is a burner, and 20 is a methanol pump. Patent Applicant: Toyota Industries Corporation, Patent Attorney: 1) Hironobu Meta/-zru

Claims (1)

[Claims] 1. A fuel cell that generates electricity using hydrogen and oxygen, and a burner that burns methanol or hydrogen and supplies the heat necessary for the methanol reforming reaction, and uses water and methanol as raw materials under a catalyst. In a fuel cell equipped with a methanol reformer that performs a methanol reforming reaction to produce hydrogen and carbon dioxide, at the same time as the fuel cell stops generating electricity, a methanol supply system for combustion of the burner is activated to convert methanol and A method for stopping the operation of a fuel cell equipped with a methanol reformer that burns unreacted hydrogen from the fuel cell and consumes the unreacted hydrogen from the fuel cell.