JPH08293315A - Desulfurizer for fuel cell generating device - Google Patents

Abstract

PURPOSE: To eliminate a partial low temperature area in the catalyst layer and adsorbent layer of a desulfurizer caused after the stop of a fuel cell generating device. CONSTITUTION: A hydrogen adding desulfurizing catalyst layer 12 for decomposing an organic sulfur compound contained in fuel into hydrogen sulfide by hydrogen addition and an adsorbent layer 13 for adsorbing hydrogen sulfide are filled in a desulfurizer 11. Further, a heat transfer accelerator for accelerating the heat transfer in the direction of fuel gas flow, for example, a heat- transfer bar 14 consisting of nickel is provided in the inner part of the catalyst layer 12 and the adsorbent layer 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generator, and more particularly to a desulfurizer for removing sulfur from raw fuel introduced into a fuel processing system.

[0002]

2. Description of the Related Art A fuel cell power generator directly converts the binding energy of hydrogen gas generated by a hydrogen generator and oxygen in the air into electric energy, and has high power generation efficiency due to the power generation by a chemical reaction. Moreover, it has been evaluated as a power generation system with excellent environmental properties such as low emission of air pollutants and low noise.

In a general fuel cell power generation system, a reformer for producing hydrogen from a hydrocarbon fuel such as city gas or propane gas, a fuel cell main body for producing electricity from hydrogen and oxygen in the air, and a fuel cell are produced. It is composed of a converter for converting the direct current into an alternating current and a heat exchanger for maintaining the temperature of the working gas at a temperature suitable for the operation of the fuel cell main body and hydrogen generation.

By the way, in order to produce hydrogen from hydrocarbon as a fuel, steam is added to the fuel to convert it into hydrogen and carbon monoxide by a catalytic reaction, and hydrogen is produced by a catalytic reaction of dispersible carbon and steam. However, the active components of these catalysts are likely to combine with sulfur, and poisoning by sulfur reduces the activity of the catalytic reaction. For this reason, it is necessary to supply fuel without sulfur content to the reformer, which is a device that produces hydrogen from fuel. As described above, the fuel cell power generation system uses a gas fuel such as city gas or propane gas, or a liquid fuel such as naphtha or kerosene.However, the liquid fuel has a sulfur content in its components, and the gas fuel has an additional component. Sulfur is added as an odorant. Therefore, the fuel is supplied to the reformer after the desulfurizer removes the sulfur content from the fuel.

FIG. 7 shows the structure of a conventional desulfurizer. Desulfurizer
Reference numeral 11 is an apparatus for removing the organic sulfur compound in the fuel by allowing the fuel to pass through the desulfurization catalyst layer contained in the container. The desulfurization catalyst layer is composed of, for example, a hydrodesulfurization catalyst 12 that decomposes hydrogen into fuel to decompose it into hydrogen sulfide, and one or several kinds of adsorbents 13 that adsorb sulfides such as hydrogen sulfide. Alternatively, it may be composed of one type of catalyst satisfying the above function.

Since the hydrogenation desulfurization reaction and the adsorption reaction have active temperatures, the hydrogen-added fuel gas supplied to the desulfurizer 1 is heated by the heat exchanger before the desulfurizer 11. By supplying the high temperature fuel gas, the desulfurizer 11 is maintained at a temperature suitable for the reaction.

[0007]

Hereinafter, a case where the desulfurization catalyst layer is composed of a catalyst layer 12 that causes a hydrodesulfurization reaction and an adsorbent layer 13 that adsorbs hydrogen sulfide and the like will be described as a typical example. The problem to be solved by the present invention occurs regardless of the structure of the desulfurization catalyst layer.

The temperatures of the catalyst layer 12 and the adsorbent layer 13 in the desulfurizer 11 are maintained at 200 ° C. or higher by passing the fuel gas heated on the upstream side of the desulfurizer 11. However,
When the operation of the power generator is stopped, the fuel system is purged by the nitrogen gas that is depressurized and supplied from the nitrogen cylinder.
This gas has a low temperature and cools the desulfurizer 11 at the most upstream side of the fuel system.

The purge flow rate of the fuel system with nitrogen gas is
Since the heat capacities are smaller than the heat capacities of the catalyst layer 12 and the adsorbent layer 13 of the desulfurizer, the temperature of the equipment downstream of the desulfurizer 11 hardly decreases. On the other hand, in the desulfurizer 11, since the catalyst layer 12 or the adsorbent layer 13 has a large specific heat and a low thermal conductivity, the temperature distribution inside the desulfurizer 11 is as shown in FIG. It is unavoidable that only the catalyst layer inlet is cooled.

When the fuel cell power generator is stopped and the temperature distribution shown in FIG. 8 is obtained by purging the fuel system, when the power generator is restarted, the fuel gas is heated to a high temperature and is desulfurized. be introduced. While the fuel gas in the desulfurizer 11 raises the temperature in the low temperature region generated at the inlet of the catalyst layer 12, it cools itself and cools the catalyst layer 12 or the adsorbent layer 13 on the downstream side. Therefore, after restarting, the temperature distribution of the catalyst layer 12 and the adsorbent layer 13 of the desulfurizer 11 changes from the temperature distribution a to the temperature distribution b, and the temperature at which the low temperature region gradually propagates to the downstream side. Show changes. Therefore, it takes a considerable amount of time to raise the temperature of the entire catalyst layer to a predetermined temperature or higher.

Since the reaction of the catalyst layer 12 and the adsorbent layer 13 is active only in a predetermined temperature range, the performance of the desulfurizer 11 is deteriorated when the low temperature range is partially present. Therefore, when restarting after the operation is stopped, there is a problem that the power generation device has to wait until the temperature rise of the entire desulfurization catalyst layer is completed before starting the power generation operation.

Further, since the low temperature region partially present in the desulfurization catalyst layer moves with time, in order to confirm the completion of the temperature rise, a plurality of temperature measurement points should be provided in the catalyst layer 12 and the adsorbent layer 13. It is necessary to install and check the temperature distribution.

In view of such a point, the present invention eliminates a partial low temperature region of the desulfurizer catalyst layer and the adsorbent layer which occurs after the fuel cell power generator is stopped, and thus restarts in a short time to perform power generation operation. An object is to provide a desulfurizer that can be restored.

[0014]

The present invention is directed to a hydrogenation desulfurization catalyst for decomposing organic sulfur compounds contained in fuel provided to a fuel cell power generator into hydrogen sulfide by hydrogenation, and an adsorption for adsorbing hydrogen sulfide and the like. In the desulfurizer configured as a material, heat transfer means for relaxing the temperature distribution in the fuel flow direction of the desulfurization catalyst layer and the adsorbent layer is provided.

[0015]

The desulfurization catalyst layer has a large heat capacity, and the decrease in the amount of heat due to the nitrogen purge of the fuel system when the power generator is stopped is small in the entire desulfurizer. Since the heat transfer means that positively promotes heat transfer in the fuel flow direction of the desulfurization catalyst layer is provided, the partially generated low temperature region is eliminated, and the temperatures of the catalyst layer and the adsorbent layer are made uniform. . As described above, the flow rate of the nitrogen purge is smaller than the heat capacity of the entire desulfurizer, so that the temperatures of the catalyst layer and the adsorbent layer are maintained at the temperatures required to keep the reaction active. Therefore, the fuel cell power generator can promptly restart the power generation operation without performing the temperature raising operation after the operation is stopped.

Further, the temperature of the catalyst layer and the adsorbent layer is made uniform by the heat transfer means for uniformizing the temperature, so that the deterioration of the performance due to the local low temperature region is eliminated. Therefore, by measuring the fluid temperature at the desulfurizer outlet. It can be confirmed that the desulfurizer is operating normally, and it is not necessary to confirm it by measuring the temperature distribution in the catalyst layer and the adsorbent layer.

Desirably, a heating means is installed at the inlet portion of the desulfurizer which is cooled by nitrogen purging to actively heat the local low temperature region and then restart the power generator. The local low temperature area is quickly eliminated, and the power generation operation can be restarted within a short time.

Alternatively, during the nitrogen purge after the stop of operation,
Since the temperature of the entire catalyst can be prevented by heating the inlet portion with the heater, it is possible to promptly return to the power generation operation when the operation is restarted.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the examples, a case where the desulfurization catalyst layer is composed of a catalyst layer that causes a hydrodesulfurization reaction and an adsorbent layer that adsorbs hydrogen sulfide and the like will be described as a typical example. It is effective regardless of the configuration.

In FIG. 1, the fuel gas mixed with hydrogen is introduced into the desulfurizer 11 from the inlet nozzle and uniformly flows into the catalyst layer 12. An adsorbent layer 13 is arranged on the downstream side of the catalyst layer 12, and hydrogen sulfide and the like decomposed from the organic sulfur compound by the hydrodesulfurization reaction in the catalyst layer 12 are adsorbed. The fuel gas from which the sulfur content has been removed is sent to the reformer. The above-described structure is the same as the structure of the conventional desulfurizer shown in FIG. 7, but a heat transfer promoter that promotes heat conduction in the fuel gas flow direction is installed inside the catalyst layer 12 and the adsorbent layer 13. Although the heat transfer promoter installed in the desulfurization catalyst layer can be configured by various means, in this embodiment, the heat transfer rod 14 made of nickel, for example, is used. In addition to this, it is possible to use a metal material that is excellent in corrosiveness to sulfur and hydrogen and is also excellent in thermal conductivity. The partial low-temperature region generated in the conventional desulfurizer uses the heat transfer rods 14 to form the catalyst layer 12 or the adsorbent layer 13
Received heat from the part that is kept at high temperature and is relaxed. The temperature inside the desulfurizer 11 is made uniform. That is, due to the nitrogen purge when the power generator is stopped, the low temperature region generated at the inlet of the catalyst layer 12 is relaxed, and the temperature distribution of the catalyst layer 12 and the adsorbent layer 13 becomes the distribution shown in FIG. Even in the process, a temperature range below the lower limit temperature required to maintain the performance of the desulfurizer 11 will not occur. Therefore, when the plant is restarted, the waiting time until the completion of the temperature rise of the desulfurizer 11 which is conventionally required is not necessary, and the power generation operation can be immediately performed.

Another embodiment will be described with reference to FIG. In the above embodiment, the same metal material was used as the heat transfer accelerator, but as shown in FIG. 3, the heat transfer rod 15 made of, for example, copper, which has a high thermal conductivity but has a corrosive defect, is made of stainless steel. It is also effective to coat it with a coating material 16 made of to form a heat transfer accelerator.

FIG. 4 shows still another embodiment. As shown in the figure, the shape of the heat transfer enhancer makes it possible to make the temperature distribution in the horizontal direction as well as in the gas flow direction uniform by using a metal net 17 or a punching plate that does not obstruct the flow of fuel gas. Is.

Further, another embodiment is shown in FIG. By disposing the heat pipe 18 as the heat transfer promoter in the catalyst layer 12 and the adsorbent layer 13, it is possible to more positively make the temperature distribution uniform.

A further different embodiment is shown in FIG.
In this embodiment, a heater 19 for heating the catalyst layer 12 is installed at the gas inlet of the catalyst layer 12. When the fuel cell power generator is stopped, it is purged with nitrogen as described above, so the catalyst layer
A low temperature region is partially generated at the inlet of 12. According to the present embodiment, by heating with the heater 19 installed at the catalyst layer inlet at the time of purging with nitrogen, the catalyst layer 12 and the adsorbent layer 13 as a whole are always maintained at a temperature at which they can perform their functions or higher. Since the inlet of the catalyst layer 12 is always kept at an appropriate temperature, the temperature on the downstream side is not lowered and is kept at an appropriate temperature.

The heating by the heater 19 can be prevented from occurring in the low temperature portion of the catalyst layer 12 by performing the heating during the purging when the plant is stopped. Alternatively, by heating the partial low-temperature region generated after purging with the heater 19 installed therein, it becomes possible to quickly raise the temperature to the minimum temperature required for the catalytic reaction or more at the time of restarting, and power generation operation. Can be transitioned to early. Moreover, according to the present embodiment, the portion to be heated by the heater 19 is limited, and it is not necessary to heat the entire catalyst layer and adsorbent layer, and a small capacity heater can restart the fuel cell power generator in a short time. Becomes

[0026]

As described above, in the present invention, the temperature distribution of the catalyst layer and the adsorbent layer in the desulfurizer is made uniform by the heat transfer means installed in the gas flow direction of the desulfurization catalyst layer in the desulfurizer. And the partial low temperature region that has conventionally been generated when the fuel cell plant was shut down is mitigated. As a result, the catalyst layer and the adsorbent layer are kept at a temperature that is functionally required or higher as a whole, so it is possible to restart the fuel cell power generator immediately after the operation is stopped and return to the power generation operation. Become.

Alternatively, the small-capacity heating means installed at the inlet of the catalyst layer of the desulfurizer can prevent the temperature of the catalyst layer from being lowered by nitrogen purging when the plant is stopped. Alternatively, the low temperature region partially generated by the nitrogen purge is heated by the heater 22 before the power generator is started, so that the temperature is rapidly raised and the restart and the power generation can be restarted promptly.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a desulfurizer for a fuel cell power generator according to the present invention.

FIG. 2 is a characteristic diagram showing a temperature transition when the desulfurizer according to the present invention is restarted.

FIG. 3 is a configuration diagram showing another embodiment of the present invention.

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a configuration diagram showing another embodiment of the present invention.

FIG. 6 is a configuration diagram showing another embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional desulfurizer.

FIG. 8 is a characteristic diagram showing a temperature transition when the conventional desulfurizer is restarted.

[Explanation of symbols]

 11 Desulfurizer 12 Catalyst layer 13 Adsorbent layer 14, 15 Heat transfer rod 16 Coating material 17 Metal mesh 18 Heat pipe 19 Heater

Continuation of the front page (51) Int.Cl. ⁶ Identification code Reference number in the agency FI Technical display location C10G 45/72 9547-4H C10G 45/72 // B01D 53/86 B01D 53/36 D

Claims (6)

[Claims] 1. A desulfurizer for removing a sulfur content of a raw fuel introduced into a fuel processing system of a fuel cell power generation device, wherein the desulfurization catalyst layer in a desulfurization catalyst layer holds a desulfurization catalyst layer in a flow direction of fuel gas. A desulfurizer for fuel cell fuel processing, comprising heat transfer means for uniformizing temperature distribution. 2. The heat transfer means for equalizing the temperature distribution in the fuel gas flow direction of the catalyst layer is composed of a metal rod having a high thermal conductivity arranged in the desulfurization catalyst layer. Item 2. A desulfurizer for fuel cell fuel processing according to Item 1. 3. The heat transfer means for equalizing the temperature distribution in the fuel gas flow direction of the catalyst layer is composed of a coated copper material disposed in the desulfurization catalyst layer.
A desulfurizer for fuel processing of the fuel cell described. 4. The heat transfer means for equalizing the temperature distribution in the fuel gas flow direction of the catalyst layer comprises a metal net or a punching plate arranged in the desulfurization catalyst layer. Desulfurizer for fuel cell fuel processing. 5. The fuel cell fuel according to claim 1, wherein the heat transfer means for uniformizing the temperature distribution in the fuel gas flow direction of the catalyst layer comprises a heat pipe arranged in the desulfurization catalyst layer. Desulfurizer for processing. 6. The desulfurizer for fuel cell fuel treatment according to claim 1, wherein a heating means is partially provided at an upstream portion of the catalyst layer.