JPH02170367A - Fuel battery with methanol modifier - Google Patents

Abstract

PURPOSE:To prevent collapse of thermal balance at a methanol modifier and providestable operation by actuating a heat emitting body installed on a catalyst layer of the methanol modifier when the temp. of the catalyst layer has sunk below the specified control temp. range, and by heating the catalyst layer. CONSTITUTION:A NiCr wire 44 to heat catalyst 14 is wound round a catalyst layer 13 of a methanol modifier 1, and current is supplied to this NiCr wire 44 to actuate is heat emission when the sensing value from a temp. sensor for the catalyst layer 13 has sunk below the specified control temp. Accordingly the heat emitted from the NiCr wire 44 heats the catalyst layer 13 even though the temp. of the modifying catalyst 14 in the catalyst layer 13 of the methanol modifying device 1 is going to sink, so that drop of the rate of methanol modification is suppressed and the specified amount of hydrogen production is kept. This prevents collapse of the thermal balance in the methanol modifying device 1 to achieve stabilized operation.

Description

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

[Prior Art] Conventionally, there have been fuel cells that generate electricity using hydrogen and oxygen, and there is a method of obtaining this hydrogen through a methanol reforming reaction. In this methanol reformer, hydrogen is produced using methanol and water as raw materials under a high-temperature catalyst, and hydrogen is supplied to the fuel cell. At the same time, unreacted hydrogen in the fuel cell is refluxed to remove the unreacted hydrogen. It is burned in a burner to obtain the heat necessary for the methanol reforming reaction.

The output of the fuel cell is controlled in correlation with the supply of reforming raw materials (methanol, water) to the methanol reformer.

In other words, the unreacted hydrogen in the fuel cell is combusted by the burner of the methanol reformer, and the optimal amount of heat is supplied to the catalyst layer of the methanol reformer so that the temperature of the catalyst layer is always around 320°C, matching the output of the fuel cell. This controls the amount of reforming raw materials (methanol, water) supplied to the methanol reformer.

[Problem to be solved by the invention] However, once the temperature of the catalyst layer of the methanol reformer starts to drop from the state where this heat balance is maintained, the methanol reforming rate decreases and the amount of hydrogen produced decreases. do. At this time, since the power generation (hydrogen utilization rate) of the fuel cell is constant, the amount of unreacted hydrogen flowing back to the burner of the methanol reformer decreases, and the temperature of the tR layer of the methanol reformer further decreases. There was a problem in that the hydrogen flame in the burner of the methanol reformer eventually went out. This occurred especially during transient conditions such as changing the output of the fuel cell.

An object of the present invention is to provide a fuel cell equipped with a methanol reformer that can perform stable operation by preventing the heat balance in the methanol reformer from collapsing due to changes in the output of the fuel cell. It is in.

[Means for Solving the Problems] The present invention is equipped with 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 as a raw material to generate hydrogen and carbon dioxide, temperature detecting means for detecting the temperature of the catalyst layer of the methanol reformer; and operating the heating element when the temperature of the catalyst layer detected by the temperature detecting means falls below a specified temperature range. The gist of the present invention is a fuel cell equipped with a methanol reformer comprising a control means for increasing the temperature of the catalyst layer.

[Operation] When the temperature detection means indicates that the temperature of the catalyst layer of the methanol reformer falls below a prescribed control temperature range, the control means operates a heating element provided in the catalyst layer to heat the catalyst layer. As a result, the temperature of the catalyst layer of the methanol reformer increases, and the collapse of the heat balance is prevented.

[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 fuel cell 2, and a DC/D
It is composed of a C converter 3, a lead-N 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 raw materials are mixed to become a reforming raw material, and are supplied to the methanol reformer 1.

The methanol reforming apparatus 1 has a cylindrical frame 11, as shown in FIG. 2 and FIG.
A heat insulating material 12 is arranged.

A plurality of catalyst layers 13 are arranged concentrically in the frame 11, and a reforming catalyst 14 is filled in the catalyst layers 13. As the reforming catalyst 14, a Cuo or ZNO type catalyst is used.

Each catalyst layer 13 is formed into a columnar shape as shown in FIG.
is wrapped in a spiral. The winding pitch of the nichrome wire 44 is narrower at the bottom. That is, the amount of heat generated by the nichrome wire 44 increases in the lower part.

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 extends spirally in the center of the frame 11, and is further connected to the bottom of each catalyst layer 13 from the branch portion 16. The upper end of each catalyst layer 13 is assembled and communicated with the outside through a hydrogen discharge pipe 17.

A part 18 is installed at the top of the inner cylinder of the frame 11.
Air (oxygen) is supplied to the burner 18 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 hydrogen is combusted by the oxygen in the air supplied by the blower 19. The high temperature combustion gas heats the reforming material supply pipe 15 and also heats each catalyst layer 13. That is, when raising the temperature of the methanol reformer @1, 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. Then, the fuel cell 2 switches to a hydrogen flame using unreacted hydrogen 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.

Further, in the catalyst layer 13, hydrogen is generated in a reforming process ts14 using methanol and water as raw materials in a high temperature atmosphere caused by combustion in the burner 18'c described above (CH30
H120 → 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 professional 926.

Furthermore, a heat exchanger (', A-il pipe) 27 for heating and cooling the fuel cell 2 is arranged in this fuel cell 2, and a heat exchanger 29 and an oil Oil is circulated through 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. Then, when starting up the fuel cell 2, methanol is burned in the starting burner 31 and the oil is heated.
The oil is circulated and the temperature of the fuel cell 2 is raised to approximately 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 oil circulating in the
The temperature of the fuel cell 2 is raised by the methanol pump 32 and the blower 33.
At the same time, the starting burner 31 is used to ignite the methanol flame, and the heat exchanger 29 heats the circulating oil.

In addition, in the fuel cell 2, hydrogen supplied from the methanol reformer 1 and air supplied by the blower 26 <'
MX>, an electromotive force is generated between the hydrogen electrode 23 and the M yarn type 24. 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/D, C 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 and 35b connected in parallel, and a transistor Tr connected in series to the travel motor 5. In addition, a flywheel diode D is connected to connection points a and b.
1°D2 is connected. The rotational speed of the travel motor 5 is controlled by chopper controlling the transistors 1 to Tr with one of the switching contactors 35a and 35b closed.

The controller 36 of C, which controls the entire system, serves as a control means for each of the blowers 19.26, 33 and the pump 7.1.
0, 20, 28, and 32, as well as a signal from a temperature sensor 37 as a temperature detection means for detecting 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. Input a signal and detect each temperature.

Further, the controller 36 detects the output voltage Vl''C of the fuel cell 2 by the voltage detection section 39, and detects the terminal voltage VB of the lead-acid battery by the voltage detection section 40. 4 is detected, and the temperature of the lead acid battery 4 is detected by the temperature sensor 43.Furthermore, the controller 1 to the roller 36 output the output current command value from the fuel cell 2 to the DC/DC converter 3. At the same time, the load contactor 41 installed between the DC/DC converter 3 and the TLA storage battery 4 is opened and closed.The controller 1 to the roller 36 are connected to the nichrome wire attached to the reforming catalyst 14 of the methanol reformer 1. 44 is controlled.

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

First, the controller 1 to the roller 36 drive the methanol pump 20 and the blower 19 to transfer methanol to the burner 18 until the temperature of the methanol reformer 1 reaches the lowest temperature at which a reforming reaction is possible (approximately 250°C). The temperature of the catalyst layer 13 is increased by combustion. At the same time, the controller 1 to the roller 36 drive 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, so that the starting part 31 burns methanol and prevents the oil from burning. pump 28
This prevents oil from circulating and raises the temperature of the fuel cell 2.

Then, when the controller 36 reaches 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 the methanol pump 10 to start supplying the reforming raw material to the methanol reformer 1. Then, hydrogen reformed by the reforming catalyst 14 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 enters the flashback preventer 34.
It is burned in the burner 1B of the methanol reformer 1.

Thereafter, the controller 36 stops the methanol pump 20 of the methanol reformer 1 and causes the methanol reformer 1 to burn the part 18 mainly with unreacted hydrogen.

The controller 36 drives the blower 26 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 oven voltage is generated between both electrodes of the fuel cell 2. After the oven 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 1-roller 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 steps according to the value. Furthermore, the controller 36 calculates the state of charge of the lead acid battery 4 by constantly detecting the terminal voltage VB, charging/discharging current I8, and temperature of the lead acid battery 4. 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 lead-acid battery 4 is being discharged, the output of the fuel cell 2 is set to the maximum side, and when the lead-acid battery 4 is sufficiently charged, the output is set to the low output side. The controller 36 stops the supply of methanol to the starting bar J31 at the same time as the fuel cell 2 starts generating electricity, and cools the fuel cell 2 with the blower 33.

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 the DC/DC converter 3 to a load such as the travel motor 5 or to the lead acid battery 4 as an auxiliary battery.
Converter 3 always outputs its output! 8, the charging voltage of the storage battery 4 is controlled to be VB, and a hybrid operation using the fuel cell 2 and the lead storage battery 4 is performed. Also, the outputs of the methanol reformer 1, fuel cell 2, and DC/DC converter 3 are set to the input side when the storage battery 4 is discharging, and lowered as the battery 4 becomes fully charged. control so that That is, the controller 36 controls the output of the fuel cell 2 in correlation to the amount of charge of the lead acid battery 4.

At this time, the reforming raw material supply ♀ from the methanol pump 10 and the water pump 7 supplies the hydrogen necessary for power generation in the fuel cell 2 and the amount of heat necessary for the methanol reforming reaction to generate the hydrogen to the fuel cell 2. The temperature of the catalyst layer of the methanol reformer 1 is set in advance to be around 320° C. at all times.

However, in a transient state where the output of the fuel cell 2 is changed, the temperature of the catalyst layer of the methanol reformer 1 fluctuates significantly. The controller roller 36 constantly detects the temperature of the catalyst layer, and when the temperature of the catalyst layer falls below the specified i+ control temperature, the nichrome wire 44 is energized and the heating operation is stopped. The heat generated by the nichrome wire 44 heats the reforming catalyst 14 of the methanol reformer 1. Therefore, the heat balance of the catalyst layer 13 of the methanol reformer 1 collapses and the reforming catalyst 14
Even if the temperature is about to drop, the catalyst layer 13 is heated by the heat generated by the nichrome wire 44, so the reduction in the methanol reforming rate is suppressed and the specified hydrogen generation port is maintained. At this time, the hydrogen port that returns from the fuel cell 2 to the burner 18 of the methanol reformer 1 does not change, and the hydrogen flame of the burner 18 does not go out.

Also, when the nichrome wire 44 generates heat, the nichrome wire 44
The winding pitch is narrower in the lower part (the lower part is nichrome wire 4).
4), the methanol/water reforming raw material introduced from below the catalyst layer 13 undergoes an active reaction on the inlet side compared to the outlet side. Therefore, catalyst layer 1
Since more heat is taken away by the reaction on the inlet side of 3, the winding density of the nichrome wire 44 is made denser on the inlet side than on the outlet side.

As described above, according to this embodiment, the catalyst layer 13 of the methanol reformer 1 is wrapped with the nichrome wire 44 that heats the catalyst, and the detected value of the temperature sensor 9'' 37 of the catalyst layer 13 is below the specified control temperature. When this occurs, the nichrome wire 44 is energized to generate heat.Therefore, the loss of thermal balance in the catalyst layer 13 of the methanol reformer 1 is avoided by the heat generated by the nichrome wire 44, and the amount of hydrogen produced is maintained. The amount of hydrogen that returns from the fuel cell 2 to the burner 18 of the methanol reformer 1 does not change and the hydrogen flame in the burner 18 does not go out.
It is possible to prevent the heat balance in the methanol reformer 1 from being lost due to changes in the output of the methanol reformer 1, and to perform stable operation.

Furthermore, when the temperature of the catalyst layer 13 of the methanol reformer 1 decreases, the methanol reforming rate decreases, and there is a risk that unreformed methanol may enter the hydrogen electrode 23 of the fuel cell 2 and cause adverse effects such as deterioration of the electrode. In this embodiment, the temperature drop of the reforming catalyst 14 is suppressed by the exothermic action of the nichrome 1iQ44, and deterioration of the hydrogen electrode 23 of the fuel cell 2 due to unreformed methanol can be avoided.

Furthermore, in this embodiment, the winding pitch of the nichrome wire 44 was narrowed on the inlet side of the reforming raw material of methanol/water.
Since a large amount of heat can be supplied at the inlet of the catalyst layer where the reaction is active, and not so much heat is required at the outlet where the reaction is not active, the temperature distribution of the reforming catalyst 14 as a whole can be made uniform.

[Effects of the Invention] As detailed above, according to the present invention, there is an excellent feature that can prevent the heat balance in the methanol reformer from collapsing due to changes in the output of the fuel cell and perform stable operation. be effective.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of the fuel cell of the example, Figure 2 is a sectional view of the methanol reformer, Figure 3 is a sectional view taken along line AA in Figure 2, and Figure 4 is a perspective view showing the reforming catalyst. It is a diagram. 1 is a methanol reformer, 2 is a fuel cell, 13 is a catalyst layer, 36 is a controller as a control means, 37 is a temperature sensor as a temperature detection means, and 44 is a nichrome wire as a heating element. Patent applicant Toyoda Automatic Loom Works Co., Ltd. Representative
Person Patent Attorney On 1) Fu Mi Methanol Figure 3 Figure 4

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. A fuel cell equipped with a methanol reformer that performs a methanol reforming reaction and generates hydrogen and carbon dioxide, comprising: a heating element provided at the bottom of the catalyst of the methanol reformer; Temperature detection means for detecting the temperature of a catalyst layer of a methanol reformer; and control means for operating the heating element to raise the temperature of the catalyst layer when the temperature of the catalyst layer detected by the temperature detection means falls below a prescribed control temperature range. A fuel cell equipped with a methanol reformer comprising: