JPS6386365A - Starting equipment for air cooled fuel cell power generator - Google Patents

Abstract

PURPOSE:To start operation of a fuel cell in a short time without drop in cell performance by installing a mixing pipeline by which heating medium exhausted from a heat exchanger is joined in a downstream passage, and installing a combuster in the douwnstream of the joining point. CONSTITUTION:A valve 25 and a damper 9 in an air cooling line 30 of a fuel cell 1 are closed and the air is circulated with a blower 5 through a circulation pipeline 35 in an oxidizing agent electrode 3, a catalysr combustor 6, and a conducting pipe 7b of a heat exchanger 7. Fuel is burned in a burner 11 of a fuel reformer 10, and mixed through pipelines 21 and 37 with the air exhasted from the heat exchanger 7. The air flowing in the conducting pipe 7b of the heat exchanger 7 is heated and mixed with the gas exhausted from the heat exchanger 7 and the high temperature mixture is supplied to the catalyst combustor 6. The uncombustion gas of the mixture gas from the combustor 6 is burned. The high temperature mixture gas flows through the air passage of the electrode 3 and the temperature of the fuel cell 1 is increased in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a starting device for an air-cooled fuel cell power generation device in which a fuel reformer and an air-cooled fuel cell are combined.

[Prior art and its problems]

A fuel cell is a device that directly converts the chemical energy of fuel into electrical energy, and has recently been adopted as a new power generation device due to its advantages such as high thermal efficiency, low noise, electrical noise, and harmful emissions. There is. A fuel cell chemically extracts electricity by supplying fuel and an oxidizer between a fuel electrode and an oxidizer electrode that sandwich an electrolyte layer. When extracting electricity from a fuel cell, heat is generated, so the fuel cell itself must be kept at an operating temperature at which it can operate efficiently, for example, in the case of a phosphoric acid fuel cell, the operating temperature should be approximately 19°C.
It is necessary to cool the fuel cell to maintain it at 0°C. There are two types of cooling methods: air-cooling and liquid-cooling, but air-cooling is more advantageous because it has a simpler system configuration, especially for small-capacity independent power supplies.

By the way, the fuel supplied to the fuel electrode of a fuel cell is hydrogen, but it is known that a fuel reformer uses reformed gas obtained by reforming the reformed raw material through a reforming catalyst into a hydrogen-rich gas. ing. In this case, it is necessary to raise the temperature of the reforming catalyst to 600 to 800°C when the reforming raw material is natural gas or LPG, and to 200 to 300°C when the reforming raw material is methanol. For this reason, the fuel is combusted in a burner of the fuel reformer, and the temperature of the reforming catalyst is raised by a heat medium such as combustion gas. In addition to the fuel from the fuel supply source, the fuel burned in the burner also includes reformed gas (hereinafter referred to as off-gas) containing unreacted hydrogen during fuel cell operation.

An air-cooled fuel cell power generation device is constructed by combining an air-cooled fuel cell and a fuel reformer as described above.

By the way, the reformed gas produced by the fuel reformer contains a small amount of carbon monoxide. This carbon oxide poisons the catalyst layer of the fuel electrode and oxidizer electrode of a phosphoric acid fuel cell, and prevents activation of the cell reaction. In order to prevent this, it is necessary to reduce the amount of carbon monoxide in the reformed gas or to increase the temperature during battery reaction.

Therefore, to start up a fuel cell, in order to reduce the poisoning effect of the catalyst by carbon monoxide, the temperature of the fuel cell is raised to about 140° C. or higher using heated air as a heat medium, and then
The fuel cell is operated.

After reaching the operating temperature of approximately 190° C., the fuel cell is cooled by air as a cooling medium to maintain the operating temperature. Note that the material that serves as a cooling or heat medium is called a cold/heat medium. In this case, there are two structures: one in which the reaction air as the reaction gas and the cold air as the cooling medium flow through separate air passages provided within the fuel cell, and the other in which they flow in the same air passage. Among these structures, it is better to flow the reaction air and the cold air together through the same air passage, as this will reduce the difference in temperature distribution within the fuel cell and improve the cell characteristics, so it is recommended to use one with this structure. is advantageous.

By the way, there is a method of raising the temperature at the time of starting a fuel cell by raising the temperature of the air with a heater, but as a way to raise the temperature in a short time, it is possible to raise the temperature of the air at the time of starting the fuel cell. It is used as a heating medium to raise the temperature of the fuel cell. However, in this method, moisture contained in the combustion gas, that is, water vapor, is condensed by the low-temperature fuel cell and becomes condensed water. This condensed water blocks the air passages and prevents air flow, and also dissolves the phosphoric acid impregnated in the electrodes and IJ hooks into the condensed water, degrading the battery characteristics.

Therefore, when raising the temperature of a fuel cell using combustion gas from a fuel reformer or startup burner, conventionally a heat exchanger with built-in heat exchanger tubes is installed as a heater, and the combustion gas is passed through the heat exchanger. By heating the air indirectly through the heat exchanger tube, moisture in the combustion gas is prevented from mixing with the heated air.

The prior art will be described below with reference to the drawings.

FIG. 3 is a system diagram of a conventional air-cooled fuel cell power generation device. In the figure, the system of the air-cooled fuel cell power generation device includes an air-cooled phosphoric acid fuel cell 1, a fuel reformer 10, and an air system 30 that has a reformed gas system 20 and a circulation pipe 35 that connect these.
It is composed of a heating system 40 and the like. A phosphoric acid type fuel cell 1 includes an IJ hook impregnated with phosphoric acid, a fuel electrode 2 and an oxidizer electrode 3 sandwiching the IJ hook.

The fuel reformer 10 includes a meandering vaporizer 13 in a case-like furnace vessel 12, a reactor 14 connected to this and filled with a reforming catalyst, and a burner 11 in the upper center of the furnace vessel 12.
is provided.

The reformed gas system 20 connects a fuel supply source (not shown) to the carburetor 13.
It consists of a pipe line that connects the burner 11 via the reactor 14 and the fuel electrode 2, and a pipe line that connects directly to the burner 11. For example, liquid methanol is vaporized as a fuel from the fuel supply source through the pipe line 15. methanol is supplied to the burner 11 through a conduit 16 branched from the conduit 15. The methanol supplied to the burner 11 is combusted in the combustion air burner 11 supplied from the pipe 17 to produce a flame and combustion gas, and the combustion gas is taken out to the outside via the discharge pipe 21. The flame and combustion gas heat the vaporizer 13 and the reactor 14, vaporize the methanol flowing through the vaporizer 13 into vaporized gas, and further convert it into hydrogen-rich gas by the action of the reforming catalyst in the reactor 14. into reformed gas. This reformed gas is supplied to the fuel electrode 2 through the pipe line 18, and is used as a reaction gas for the fuel cell together with the reaction air that flows through the air system 30 and is supplied to the oxidizer electrode 3. Off-gas generated when the fuel cell is operated with the reactant gas is supplied from the fuel electrode 2 to the burner 11 via a conduit 19 and used as fuel. In normal operating conditions, off-gas is sufficient to supply fuel to burner 11, so pipe 1
The methanol supply from 6 is stopped.

The air system 30 includes a circulation blower 5 provided in the artificial conduit 22 of the oxidizer electrode 3 and a damper 9 provided in the outlet conduit 23.
A heat transfer tube 7 is connected to the pipe line 24 between the damper 9 and the circulation blower 5.
A circulation pipe 3 provided with a heat exchanger 7 containing a
5, a conduit 26 for supplying make-up air equipped with a valve 25 to the suction part of the circulation blower 5, and a circulation conduit 35 from the damper 9.
It is composed of a discharge pipe 29 that discharges a part of the flowing air to the outside by adjusting the damper 9, and when the fuel cell is started, air heated by the heat exchanger 7 is supplied to the air passage of the oxidizer electrode 3. I'm trying to send it in. Note that during operation, the starting burner 8 is stopped and air is made to flow through the air system 30 and is sent to the air passage of the oxidizer electrode 3.

The heating system 40 consists of a pipe line connecting a fuel supply source and the heat exchanger 7. That is, a starting burner 8 is connected to the heat exchanger 7 by a pipe 28 branched from the pipe 15, and the methanol that has passed through the pipe 28 is combusted in the starting burner 8 by combustion air from a pipe 39. This combustion gas is supplied to the heat exchanger tubes 7a of the heat exchanger 7, heat is exchanged with the air flowing through the heat exchanger 7 to heat the air, and the exhaust gas is discharged to the outside via the pipe line 32. .

With this configuration, the temperature of the fuel cell 1 can be increased when the fuel cell 1 is started by closing the valve 25 and damper 9 and driving the circulation blower 5 to circulate air through the circulation pipe 35 of the air system 30. This is done by exchanging heat between the combustion gas combusted in the starting burner 8 and the air in the circulation pipe in the heat exchanger 7, and passing the heated air through the air passage of the oxidizer electrode 3. , the temperature of the fuel cell 1 is raised to about 140°C. Once the temperature has been raised, the starting burner 8 is stopped and the fuel cell is operated. In this case, the air flowing through the air system 30 removes the heat generated by the fuel cell 1 and maintains it at the operating temperature.

By the way, as mentioned above, the combustion gas from the starting burner 8 flows through the heat exchanger tubes 7a of the heat exchanger 7, and heat is exchanged with the air flowing through the heat exchanger 7 via the heat exchanger tubes 7a, so that combustion Moisture in the gas does not mix into the air. As a result, the battery characteristics do not deteriorate, but it takes a long time to raise the temperature of the air to a specified temperature due to indirect heating due to heat exchange through heat transfer tubes. It is disadvantageous.

Note that the burner 11 of the fuel reformer is used instead of the startup burner.
Even if the gas combusted in a heat exchanger is used to heat the air, there are the same drawbacks.

[Purpose of the invention]

In view of the above-mentioned points, the present invention provides a starting device for an air-cooled fuel cell power generation device that can start up the fuel cell of the air-cooled fuel cell power generation device in a short time without deteriorating the cell characteristics. It's about doing.

[Key points of the invention]

According to the present invention, the above object is to provide a fuel reformer that converts a reformed raw material into a hydrogen-rich reformed gas, a fuel cell to which this reformed gas is supplied, and a blower to supply air to the fuel cell. a heat exchanger provided thermally in the circulation pipe, a passage for supplying the heat medium obtained by combusting the reforming raw material in a burner to the heat exchanger; This is achieved by providing a combustor/J on the downstream side.

[Embodiments of the invention]

The present invention will be described in detail below based on the drawings.

FIG. 1 is a system diagram of an air-cooled fuel cell power generator equipped with a starter device according to an embodiment of the present invention. In FIG. 1 and FIG. 2, which will be described later, parts that are the same as those in the conventional example shown in FIG. Pipe line 31 on the downstream side of 7
The mixing pipe 3 connects to the air in the circulation pipe 35 and joins the air in the circulation pipe 35.
2 is provided, and furthermore, a catalytic combustor 6 as a combustor is provided in a pipe 36 on the suction side of the III blower 5 downstream from this confluence point. In addition, in this embodiment, the combustion gas from the burner 11 of the fuel reformer 10 causes the circulation pipe to
In order to heat the air circulating through the fuel reformer 5 in the heat exchanger 7, the exhaust pipe 21 of the fuel reformer 10 is connected to the heat exchanger 7 by a pipe line 37 via a damper 33. The damper 33 is also connected to the exhaust pipe 34 and switches between discharging the combustion gas to the outside through the exhaust pipe 34 and supplying the combustion gas to the heat exchanger 7 through the pipe line 37. The catalytic combustor 6 is made by disposing a platinum catalyst in a ceramic porous body, and has the advantage of burning combustible gas at a relatively low temperature and being able to burn even dilute combustible gas.

A method of starting up the fuel cell 1 by raising its temperature using such a configuration will be explained. First, the valve 25 and damper 9 of the air system 30 of the fuel cell 1 are closed, and the circulation blower 5 is driven to circulate air through the circulation pipe 35, thereby exchanging heat with the air passage of the oxidizer electrode 3 of the fuel cell 1. The heat exchanger tube 7b of the vessel 7 and the catalytic combustor 6 are made to flow through each other.

In this state, fuel is combusted in the burner 11 of the fuel reformer 10, and the combustion gas is caused to flow through the heat exchanger 7 through the pipes 21 and 37 by switching the damper 33, and the mixed pipe 32 The air is mixed with the air discharged from the heat exchanger 7 through the air. As a result, the air flowing through the heat exchanger tubes 7b of the heat exchanger 7 is indirectly heated by heat exchange with the high-temperature combustion gas through the heat exchanger tubes 7b, and then is discharged from the heat exchanger 7. By mixing the combustion gas, the mixture of air and combustion gas becomes high in temperature in a short time and flows into the catalytic combustor 6. At this time, the high-temperature combustion gas that has flowed into the heat exchanger 7 becomes low-temperature combustion gas through heat exchange.

For this reason, as described above, the water vapor present in the combustion gas is condensed into water as the combustion gas itself becomes low temperature through heat exchange, and is discharged to the outside from a drain discharge pipe (not shown).

Further, this high-temperature gaseous mixture of air and combustion gas flows through the catalytic combustor 6 and then through the air passage of the oxidizer electrode 3 of the fuel cell 1. At this time, unburned gas contained in the combustion gas is combusted in the catalytic combustor 6 as described above. Note that unburned gas reacts in the catalyst layer of the electrode and deteriorates the battery characteristics.

Therefore, the high-temperature mixed gas flows through the air passage of the oxidizer electrode 3 in a state that does not contain moisture and unburned gas that degrade the cell characteristics, raising the temperature of the fuel cell in a short time. In this case, an amount of the mixed gas circulating in the circulation pipe corresponding to the amount of combustion gas mixed into the circulation pipe 35 via the mixing pipe 32 is discharged to the outside from the damper 9, and a predetermined amount of gas is supplied to the circulation pipe 35. Allow the gas mixture to flow.

After heating the fuel cell 1 to a predetermined temperature using the high-temperature mixed gas in this way, the reformed gas flowing from the fuel reformer 10 through the pipe line 18 to the fuel gas passage of the fuel electrode 2 is used to fuel the fuel cell 1. 1 is driven. Note that when the temperature of the fuel cell has finished rising, the damper 33 is switched to discharge the combustion gas from the exhaust pipe 34, the flow of the combustion gas to the heat exchanger 7 is stopped, and the circulation pipe of the air system 30 is switched instead. 35, the fuel cell is operated by operating the valve 25 and damper 9 to circulate the reaction gas and the air serving as the cooling medium. Heat generated during operation of the fuel cell is removed by the aforementioned circulating air, and the operating temperature is maintained.

FIG. 2 is a system diagram of an air-cooled fuel cell power generator equipped with a starter device according to a different embodiment of the present invention.

In this embodiment, instead of using the burner of the fuel reformer 10, a heat medium obtained by combusting a part of the reformed raw material in the starting burner 8 is sent to the heat exchanger 7, but the same effect as described above can be obtained. .

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the reaction gas flowing through the air passage in the fuel cell and the air as a cooling medium are exchanged with heat from the fuel reformer or the startup burner in the heat exchanger. After indirect heating by heat exchange with the medium and removal of moisture in the combustion gas, the heating medium discharged from the heat exchanger is mixed with air in the outlet pipe of the heater to produce high-temperature combustion gas. By increasing the temperature of the fuel cell,
A high-temperature gas mixture can be obtained in a short time, and since the gas mixture does not contain moisture or unburned gas, the fuel cell can be started up by heating up in a short time using the high-temperature gas mixture, and the cell characteristics will not deteriorate. effective.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an air-cooled fuel cell power generation device according to an embodiment of the present invention, FIG. 2 is a system diagram of a starting device for an air-cooled fuel cell power generation device according to a different embodiment of the present invention, and FIG. 3 is a system diagram of a conventional air-cooled fuel cell power generation device. FIG. 1 is a system diagram of an air-cooled fuel cell power generation device. 10 fuel reformer, 11 burner, 30 air system, 32 mixed pipe, 35 circulation pipe. ! /Concave 2nd Ward

Claims (1)

[Scope of Claims] 1) A fuel reformer that converts reformed raw material into hydrogen-rich reformed gas, a fuel cell to which this reformed gas is supplied, and a circulation pipe that supplies air to the fuel cell by a blower. an air-cooled fuel cell power generation device comprising: a heat exchanger provided thermally in the circulation pipe; and a heating pipe that supplies a heat medium obtained by combusting the reformed raw material in a burner to the heat exchanger. In the starting device, a mixing pipe is provided for merging the heat medium discharged from the heat exchanger into a circulation pipe on the downstream side of the heat exchanger, and a combustor is provided on the downstream side of the merging point. A starting device for air-cooled fuel cell power generation equipment. 2) The starting device for an air-cooled fuel cell power generation device according to claim 1, wherein the combustor is a catalytic combustor.