JP4377618B2 - Steam reformer for fuel cell power generation system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steam reformer that reforms a hydrocarbon fuel to generate a hydrogen-containing gas of a fuel cell power generation system.
[0002]
[Prior art]
In the fuel cell power generation system, the hydrogen-containing gas supplied to the fuel cell main body is generated by steam reforming a hydrocarbon fuel with a steam reformer. Here, hydrocarbon fuel gas and steam are input to the steam reformer, and the fuel gas and steam are reacted with a reforming catalyst heated to a high temperature of 600 ° C. or higher to generate hydrogen and carbon monoxide. At the time of shutdown for stopping the steam reforming, unreacted fuel gas and steam remain in the reforming catalyst. Therefore, it is necessary to purge them.
[0003]
Therefore, a method is known in which the reformed gas once reformed by the steam reformer is stored in a buffer tank, and the steam reformer is purged using the reformed gas stored in the buffer tank at the time of shutdown. ing. There exists patent document 1 in such a thing.
[0004]
[Patent Document 1]
JP-A-3-247501 gazette
[Problems to be solved by the invention]
However, the reformed gas used for the purge of the steam reformer also contains a large amount of steam, and this steam is condensed while the steam reformer heated to 600 ° C. or more is cooled and the temperature is lowered. As a result, water was generated, which could corrode the reforming catalyst and the steam reformer itself.
[0006]
[Means for Solving the Problems]
Accordingly, in order to solve the above-described problems, the present invention provides a reforming catalyst that generates a hydrogen-containing gas from hydrocarbon fuel and steam, a flow path filled with the reforming catalyst, and the flow path. A steam reformer including a burner that heats the reforming catalyst to a temperature suitable for a reforming reaction from the outside, from a portion where the reforming catalyst is filled downstream of the burner and at the lower end of the flow path. also it provided a small condensation chamber heat capacity, water vapor cooling the condensing chamber by air purge of the burner at shutdown from the outside in the channel and so as to condense in the condensing chamber.
[0007]
As a result, the air purge of the burner at the time of shutting down the steam reformer cools and condenses the steam in the reforming catalyst channel, which has been in a high temperature environment, but has a smaller heat capacity than in the reforming catalyst. Since the water vapor is cooled first and water vapor is condensed in the condensing chamber, the reforming catalyst and the water vapor reformer are not corroded by the condensed water, and the life of the equipment can be extended.
[0008]
According to a second aspect of the present invention, a discharge pipe for discharging condensed water to the outside is connected to the condensation chamber, and an opening / closing means is provided in the discharge pipe.
[0009]
Thus, the condensed catalyst can be drained out of the steam reformer while keeping the reforming catalyst in a reducing environment with a simple configuration.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a system diagram of a fuel cell power generation system of the present invention. 1 is a desulfurizer that removes sulfur components that are poisons of the reforming catalyst from hydrocarbon fuel, 2 is a steam reformer that generates hydrogen-containing gas by introducing the hydrocarbon fuel and steam desulfurized by the desulfurizer 1, 3 is a burner as a heating means for heating the steam reformer 2 to a temperature suitable for the reforming reaction (here, 600 ° C. or higher), and 4 is a hydrogen-containing gas generated by the steam reformer 2. shift reactor for converting CO contained in CO ₂ and H _2, 5 is CO remover for removing by converting the CO which has not been removed by the shift reactor 4 to CO _2, 6 is hydrogen in the hydrogen-containing gas And a fuel cell body that generates electricity by electrochemically reacting oxygen in the air.
[0011]
The fuel cell main body 6 has a structure in which a fuel electrode 6b and an air electrode 6c are arranged on both sides via a proton conductive solid polymer membrane 6a, and a hydrogen-containing gas is supplied to the fuel electrode 6b so that hydrogen is protonated. While being decomposed into electrons, air is supplied to the air electrode 6c, oxygen, protons passing through the solid polymer membrane 6a, and electrons from the fuel electrode 6b flowing through the external circuit react to generate water. Power is generated from hydrogen-containing gas and air.
[0012]
The hydrogen-containing gas is used for power generation at the fuel electrode 6b, but not all hydrogen is used for power generation, and the off-gas that partially passes through the fuel electrode 6b is a steam reformer. 2 is supplied as fuel to a burner 3 for heating 2.
[0013]
The steam reformer 2 requires a means for providing reaction heat because the reforming reaction is an endothermic reaction. As shown in FIG. 2, the steam reformer 2 is reformed in the space 3a heated by the combustion of the burner 3. A flow path 2b filled with the catalyst 2a is arranged, the heat necessary for the reaction is supplied by the burner 3 and heated to a temperature suitable for the reforming reaction, and the fuel desulfurized by the desulfurizer 1 And the steam generated in a separate process flows through the flow path 2a filled with the reforming catalyst 2a, is reformed into a hydrogen-containing gas containing a large amount of H ₂ and a small amount of CO, and flows out. Is.
[0014]
The lower end of the flow path 2b filled with the reforming catalyst 2a is provided with a condensing chamber 7 having a smaller heat capacity than the portion of the flow path 2b filled with the reforming catalyst 2a. It is made to condense in the condensing chamber 7. Here, the inside of the condensing chamber 7 is a space not filled with the reforming catalyst 2a, and the heat capacity is reduced, and the reforming catalyst 2a is prevented from flowing out from the lower end of the flow path 2b via a net or punching metal. The flow path 2b and the condensing chamber 7 are partitioned so that gas can flow.
[0015]
The condensing chamber 7 is connected to a drain pipe 7a for discharging condensed water to the outside and an opening / closing means 7b for opening and closing the drain pipe 7a.
Next, 8 is a buffer tank that is provided between the steam reformer 2 and the fuel cell body 6 and temporarily stores a hydrogen-containing gas. When the hydrogen-containing gas is temporarily stored in the buffer tank 8 and the power load suddenly changes, the amount of hydrogen-containing gas supplied to the fuel cell body 6 can be adjusted to follow the power generation amount, and the fuel The unreacted fuel gas and water vapor in the steam reformer 2 are purged with the hydrogen-containing gas in the buffer tank 8 when the battery power generation system is stopped.
[0017]
As the steam reformer 2 is shut down, the steam reformer 2 that has been heated to a high temperature (here, 600 ° C. or higher) suitable for the reforming reaction is cooled by the air purge of the burner 3, The purging hydrogen-containing gas from the buffer tank 8 supplied to the flow path 2b filled with the reforming catalyst 2a to purge the steam reformer 2 is also cooled.
[0018]
However, since the condensation chamber 7 having a smaller heat capacity than that of the portion filled with the reforming catalyst 2a is cooled first, the water vapor contained in the hydrogen-containing gas is condensed in the condensation chamber 7 to produce water. At this time, the water vapor in the flow path 2b is condensed in the condensing chamber 7, and the concentration of the water vapor is gradually reduced so that the condensed water contacting the reforming catalyst 2a can be reduced as much as possible, and the reforming catalyst 2a is condensed. Does not get wet with water and does not degrade catalyst performance.
[0019]
The condensed water condensed in the condensing chamber 7 is temporarily stored in the condensing chamber 7. Further, the condensed water that has condensed at the portion filled with the reforming catalyst 2a also flows down and is stored in the condensing chamber 7 provided at the lower end of the flow path 2b. When the system is repeatedly started and stopped and a certain amount of condensed water is stored in the condensing chamber 7, when the opening / closing means 7b is opened, it is discharged to the outside through the drain pipe 7a. The opening / closing means 7b may be opened each time the system is shut down. Since the drain pipe 7a is normally closed, the reforming catalyst 2a can be maintained in a reducing environment.
[0020]
Thus, since the condensing chamber 7 is provided at the lower end of the flow path 2b filled with the reforming catalyst 2a of the steam reformer 2, the reforming catalyst 2a is immersed in the condensed water due to a temperature drop due to shutdown. The reforming catalyst 2a and the steam reformer 2 themselves are no longer corroded by the condensed water, and the lifespan of the reforming catalyst 2a and the steam reformer 2 can be extended as compared with the prior art.
[0021]
The present invention is not limited to the one embodiment described above, and the shape of the flow path 2b filled with the reforming catalyst 2a of the steam reformer 2 may be any shape. The purpose can be achieved if the condensing chamber 6 is provided at a position where the condensed water flows in the flow path 2b filled with the reforming catalyst 2a in the installed state.
[0022]
Further, as shown in FIG. 3, cooling means 7c such as fins may be provided outside the condensing chamber 7 so that the condensing chamber 7 can be more easily cooled than the flow path 2b filled with the reforming catalyst 2a.
[0023]
【The invention's effect】
As described above, according to the present invention, the steam in the reforming catalyst channel that has been in a high temperature environment is cooled and condensed by the air purge of the burner when the steam reformer is shut down. The condensing chamber having a smaller heat capacity than the inside is cooled first, and the steam is condensed in the condensing chamber, so that the reforming catalyst and the steam reformer are not corroded by the condensed water , and the equipment life can be extended. Is.
[Brief description of the drawings]
FIG. 1 is a system diagram of a fuel cell power generation system according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a steam reformer of the same embodiment.
FIG. 3 is a schematic configuration diagram of a steam reformer according to another embodiment of the present invention.
[Explanation of symbols]
2 Steam reformer 2a Reforming catalyst 2b Flow path 3 Burner 7 Condensing chamber 7a Drain pipe 7b Opening / closing means

Claims (2)

A reforming catalyst that generates a hydrogen-containing gas from hydrocarbon fuel and steam, a flow path filled with the reforming catalyst, and heating the reforming catalyst from the outside of the flow path to a temperature suitable for the reforming reaction wherein the steam reformer with a burner, a small condensation chamber heat capacity than sites reforming catalyst on the downstream side and the lower end of the flow path of the burner is filled provided by air purge of the burner on shutdown to steam reformer of a fuel cell power generation system characterized by the water vapor in the flow path to cool the condensing chamber from the outside and so as to condense in the condensing chamber.   2. A steam reformer for a fuel cell power generation system according to claim 1, wherein a discharge pipe for discharging condensed water to the outside is connected to the condensation chamber, and an opening / closing means is provided in the discharge pipe.

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